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Germaine I, Richey NE, Huttel MB, McElwee-White L. Aerosol-Assisted Chemical Vapor Deposition of 2H-WS 2 From Single-Source Tungsten Dithiolene Precursors. JOURNAL OF MATERIALS CHEMISTRY. C 2024; 12:3526-3534. [PMID: 38756620 PMCID: PMC11095848 DOI: 10.1039/d3tc03755j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2024]
Abstract
The tungsten carbonyl dimethyldithiolene (dmdt) complexes W(CO)4(dmdt), W(CO)2(dmdt)2, and W(dmdt)3 were evaluated as potential single-source precursors for the chemical vapor deposition of WS2. The results of TGA-MS, DIP-MS, and pyrolysis with NMR analysis were consistent with a thermal decomposition pathway in which loss of 2-butyne through a retro[3+2]cycloaddition of the dithiolene ligand generated terminal sulfido ligands. Aerosol-assisted chemical vapor deposition onto silicon substrates was performed using all three complexes, yielding 2H-WS2 thin films as characterized by Raman spectroscopy and GI-XRD. Film morphology and elemental composition of the films were determined using SEM, EDS, and XPS. Four-point probe measurements afforded a film resistivity of 8.37 Ωcm for a sample deposited from W(dmdt)3 in toluene at 600 °C.
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Affiliation(s)
- Ian Germaine
- Department of Chemistry, University of Florida, Gainesville, Florida 32611 USA
| | - Nathaniel E Richey
- Department of Chemistry, University of Florida, Gainesville, Florida 32611 USA
| | - Mary B Huttel
- Department of Chemistry, University of Florida, Gainesville, Florida 32611 USA
| | - Lisa McElwee-White
- Department of Chemistry, University of Florida, Gainesville, Florida 32611 USA
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2
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Burgmayer SJN, Kirk ML. Advancing Our Understanding of Pyranopterin-Dithiolene Contributions to Moco Enzyme Catalysis. Molecules 2023; 28:7456. [PMID: 38005178 PMCID: PMC10673323 DOI: 10.3390/molecules28227456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Revised: 10/23/2023] [Accepted: 10/24/2023] [Indexed: 11/26/2023] Open
Abstract
The pyranopterin dithiolene ligand is remarkable in terms of its geometric and electronic structure and is uniquely found in mononuclear molybdenum and tungsten enzymes. The pyranopterin dithiolene is found coordinated to the metal ion, deeply buried within the protein, and non-covalently attached to the protein via an extensive hydrogen bonding network that is enzyme-specific. However, the function of pyranopterin dithiolene in enzymatic catalysis has been difficult to determine. This focused account aims to provide an overview of what has been learned from the study of pyranopterin dithiolene model complexes of molybdenum and how these results relate to the enzyme systems. This work begins with a summary of what is known about the pyranopterin dithiolene ligand in the enzymes. We then introduce the development of inorganic small molecule complexes that model aspects of a coordinated pyranopterin dithiolene and discuss the results of detailed physical studies of the models by electronic absorption, resonance Raman, X-ray absorption and NMR spectroscopies, cyclic voltammetry, X-ray crystallography, and chemical reactivity.
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Affiliation(s)
| | - Martin L. Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, NM 87131, USA
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3
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Burgmayer SJN. Making Moco: A Personal History. Molecules 2023; 28:7296. [PMID: 37959716 PMCID: PMC10649979 DOI: 10.3390/molecules28217296] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 10/19/2023] [Accepted: 10/23/2023] [Indexed: 11/15/2023] Open
Abstract
This contribution describes the path of my nearly forty-year quest to understand the special ligand coordinated to molybdenum and tungsten ions in their respective enzymes. Through this quest, I aimed to discover why nature did not simply use a methyl group on the dithiolene that chelates Mo and W but instead chose a complicated pyranopterin. My journey sought answers through the synthesis of model Mo compounds that allowed systematic investigations of the interactions between molybdenum and pterin and molybdenum and pterin-dithiolene and revealed special features of the pyranopterin dithiolene chelate bound to molybdenum.
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Kirk ML, Lepluart J, Yang J. Resonance Raman spectroscopy of pyranopterin molybdenum enzymes. J Inorg Biochem 2022; 235:111907. [PMID: 35932756 PMCID: PMC10575615 DOI: 10.1016/j.jinorgbio.2022.111907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Revised: 05/16/2022] [Accepted: 06/16/2022] [Indexed: 10/17/2022]
Abstract
Resonance Raman spectroscopy (rR) is a powerful spectroscopic probe that is widely used for studying the geometric and electronic structure of metalloproteins. In this focused review, we detail how resonance Raman spectroscopy has contributed to a greater understanding of electronic structure, geometric structure, and the reaction mechanisms of pyranopterin molybdenum enzymes. The review focuses on the enzymes sulfite oxidase (SO), dimethyl sulfoxide reductase (DMSOR), xanthine oxidase (XO), and carbon monoxide dehydrogenase. Specifically, we highlight how Mo-Ooxo, Mo-Ssulfido, Mo-Sdithiolene, and dithiolene CC vibrational modes, isotope and heavy atom perturbations, resonance enhancement, and associated Raman studies of small molecule analogs have provided detailed insight into the nature of these metalloenzyme active sites.
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Affiliation(s)
- Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001, United States.
| | - Jesse Lepluart
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001, United States
| | - Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, NM 87131-0001, United States
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Gates C, Varnum H, Getty C, Loui N, Chen J, Kirk ML, Yang J, Nieter Burgmayer SJ. Protonation and Non-Innocent Ligand Behavior in Pyranopterin Dithiolene Molybdenum Complexes. Inorg Chem 2022; 61:13728-13742. [PMID: 36000991 PMCID: PMC10544801 DOI: 10.1021/acs.inorgchem.2c01234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The complex [TEA][Tp*MoIV(O)(S2BMOPP)] (1) [TEA = tetraethylammonium, Tp* = tris(3,5-dimethylpyrazolyl)hydroborate, and BMOPP = 6-(3-butynyl-2-methyl-2-ol)-2-pivaloyl pterin] is a structural analogue of the molybdenum cofactor common to all pyranopterin molybdenum enzymes because it possesses a pyranopterin-ene-1,2-dithiolate ligand (S2BMOPP) that exists primarily in the ring-closed pyrano structure as a resonance hybrid of ene-dithiolate and thione-thiolate forms. Compound 1, the protonated [Tp*MoIV(O)(S2BMOPP-H)] (1-H) and one-electron-oxidized [Tp*MoV(O)(S2BMOPP)] [1-Mo(5+)] species have been studied using a combination of electrochemistry, electronic absorption, and electron paramagnetic resonance (EPR) spectroscopy. Additional insight into the nature of these molecules has been derived from electronic structure computations. Differences in dithiolene C-S bond lengths correlate with relative contributions from both ene-dithiolate and thione-thiolate resonance structures. Upon protonation of 1 to form 1-H, large spectroscopic changes are observed with transitions assigned as Mo(xy) → pyranopterin metal-to-ligand charge transfer and dithiolene → pyranopterin intraligand charge transfer, respectively, and this underscores a dramatic change in electronic structure between 1 and 1-H. The changes in electronic structure that occur upon protonation of 1 are also reflected in a large >300 mV increase in the Mo(V/IV) redox potential for 1-H, resulting from the greater thione-thiolate resonance contribution and decreased charge donation that stabilize the Mo(IV) state in 1-H with respect to one-electron oxidation. EPR spin Hamiltonian parameters for one-electron-oxidized 1-Mo(5+) and uncyclized [Tp*MoV(O)(S2BDMPP)] [3-Mo(5+)] [BDMPP = 6-(3-butynyl-2,2-dimethyl)-2-pivaloyl pterin] are very similar to each other and to those of [Tp*MoVO(bdt)] (bdt = 1,2-ene-dithiolate). This indicates that the dithiolate form of the ligand dominates at the Mo(V) level, consistent with the demand for greater S → Mo charge donation and a corresponding increase in Mo-S covalency as the oxidation state of the metal is increased. Protonation of 1 represents a simple reaction that models how the transfer of a proton from neighboring acidic amino acid residues to the Mo cofactor at a nitrogen atom within the pyranopterin dithiolene (PDT) ligand in pyranopterin molybdenum enzymes can impact the electronic structure of the Mo-PDT unit. This work also illustrates how pyran ring-chain tautomerization drives changes in resonance contributions to the dithiolene chelate and may adjust the reduction potential of the Mo ion.
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Affiliation(s)
- Cassandra Gates
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Haley Varnum
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Catherine Getty
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Natalie Loui
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Ju Chen
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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6
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González PJ, Rivas MG, Ferroni FM, Rizzi AC, Brondino CD. Electron transfer pathways and spin–spin interactions in Mo- and Cu-containing oxidoreductases. Coord Chem Rev 2021. [DOI: 10.1016/j.ccr.2021.214202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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7
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Dille SA, Colston KJ, Ratvasky SC, Pu J, Basu P. Interligand communication in a metal mediated LL'CT system - a case study. RSC Adv 2021; 11:24381-24386. [PMID: 34354823 PMCID: PMC8285364 DOI: 10.1039/d1ra04716g] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 07/06/2021] [Indexed: 11/22/2022] Open
Abstract
A series of oxo-Mo(iv) complexes, [MoO(Dt2−)(Dt0)] (where Dt2− = benzene-1,2-dithiol (bdt), toluene-3,4-dithiol (tdt), quinoxaline-2,3-dithiol (qdt), or 3,6-dichloro-benzene-1,2-dithiol (bdtCl2); Dt0 = N,N′-dimethylpiperazine-2,3-dithione (Me2Dt0) or N,N′-diisopropylpiperazine-2,3-dithione (iPr2Dt0)), possessing a fully oxidized and a fully reduced dithiolene ligand have been synthesized and characterized. The assigned oxidation states of coordinated dithiolene ligands are supported with spectral and crystallographic data. The molecular structure of [MoO(tdt)(iPr2Dt0)] (6) demonstrates a large ligand fold angle of 62.6° along the S⋯S vector of the Dt0 ligand. The electronic structure of this system is probed by density functional theory (DFT) calculations. The HOMO is largely localized on the Dt2− ligand while virtual orbitals are mostly Mo and Dt0 in character. Modeling the electronic spectrum of 6 with time dependent (TD) DFT calculations attributes the intense low energy transition at ∼18 000 cm−1 to a ligand-to-ligand charge transfer (LL′CT). The electron density difference map (EDDM) for the low energy transition depicts the electron rich Dt2− ligand donating charge density to the redox-active orbitals of the electron deficient Dt0 ligand. Electronic communication between dithiolene ligands is facilitated by a Mo-monooxo center and distortion about its primary coordination sphere. The interligand communication between non-innocent dithiolene ligands of different oxidation states has been described in a Mo system. The fully reduced ene-dithiolate (Dt2−) acts as a donor moiety to the oxidized dithione (Dt0) in an LL′CT process.![]()
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Affiliation(s)
- Sara A Dille
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Kyle J Colston
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Stephen C Ratvasky
- Department of Chemistry and Biochemistry, Duquesne University Pittsburgh PA 15282 USA
| | - Jingzhi Pu
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
| | - Partha Basu
- Department of Chemistry and Chemical Biology, Indiana University - Purdue University Indianapolis Indianapolis IN 46202 USA
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8
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Kirk ML, Kc K. Molybdenum and Tungsten Cofactors and the Reactions They Catalyze. Met Ions Life Sci 2020; 20:/books/9783110589757/9783110589757-015/9783110589757-015.xml. [PMID: 32851830 PMCID: PMC8176780 DOI: 10.1515/9783110589757-015] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2023]
Abstract
The last 20 years have seen a dramatic increase in our mechanistic understanding of the reactions catalyzed by pyranopterin Mo and W enzymes. These enzymes possess a unique cofactor (Moco) that contains a novel ligand in bioinorganic chemistry, the pyranopterin ene-1,2-dithiolate. A synopsis of Moco biosynthesis and structure is presented, along with our current understanding of the role Moco plays in enzymatic catalysis. Oxygen atom transfer (OAT) reactivity is discussed in terms of breaking strong metal-oxo bonds and the mechanism of OAT catalyzed by enzymes of the sulfite oxidase (SO) family that possess dioxo Mo(VI) active sites. OAT reactivity is also discussed in members of the dimethyl sulfoxide (DMSO) reductase family, which possess des-oxo Mo(IV) sites. Finally, we reveal what is known about hydride transfer reactivity in xanthine oxidase (XO) family enzymes and the formate dehydrogenases. The formal hydride transfer reactivity catalyzed by xanthine oxidase family enzymes is complex and cleaves substrate C-H bonds using a mechanism that is distinct from monooxygenases. The chapter primarily highlights developments in the field that have occurred since ~2000, which have contributed to our collective structural and mechanistic understanding of the three canonical pyranopterin Mo enzymes families: XO, SO, and DMSO reductase.
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9
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Abstract
Here we highlight past work on metal-dithiolene interactions and how the unique electronic structure of the metal-dithiolene unit contributes to both the oxidative and reductive half reactions in pyranopterin molybdenum and tungsten enzymes. The metallodithiolene electronic structures detailed here were interrogated using multiple ground and excited state spectroscopic probes on the enzymes and their small molecule analogs. The spectroscopic results have been interpreted in the context of bonding and spectroscopic calculations, and the pseudo-Jahn-Teller effect. The dithiolene is a unique ligand with respect to its redox active nature, electronic synergy with the pyranopterin component of the molybdenum cofactor, and the ability to undergo chelate ring distortions that control covalency, reduction potential, and reactivity in pyranopterin molybdenum and tungsten enzymes.
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Affiliation(s)
- Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, USA
| | - John H. Enemark
- Department of Chemistry Biochemistry, University of Arizona, Tucson, AZ 85721, USA
| | - Martin L. Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, Albuquerque, NM 87131-0001, USA
- Correspondence: ; Tel.: +1-505-277-5992
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10
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Wang SY, Dai JW, Chen HB, Zhou ZH. 2,2′-Bipyridine or 1,10-phenanthroline chelated oxomolybdenum(V) complexes with glycolate, lactate and malate in acidic media. Inorganica Chim Acta 2019. [DOI: 10.1016/j.ica.2019.03.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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11
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Gisewhite DR, Nagelski AL, Cummins DC, Yap GPA, Burgmayer SJN. Modeling Pyran Formation in the Molybdenum Cofactor: Protonation of Quinoxalyl-Dithiolene Promoting Pyran Cyclization. Inorg Chem 2019; 58:5134-5144. [PMID: 30942584 PMCID: PMC6572731 DOI: 10.1021/acs.inorgchem.9b00194] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mononuclear Mo and W enzymes require a unique ligand known as molybdopterin (MPT). This ligand binds the metal through a dithiolene chelate, and the dithiolene bridges a reduced pyranopterin group. Pyran scission and formation have been proposed as a reaction of the MPT ligand that may occur within the enzymes to adjust reactivity at the Mo atom. We address this issue by investigating oxo-Mo(IV) model complexes containing dithiolenes substituted by pterin or quinoxaline and a hydroxyalkyl poised to form a pyran ring. While the pterin-dithiolene model complex exhibits a low energy, reversible pyran cyclization, here we report that pyran cyclization does not spontaneously occur in the quinoxalyl-dithiolene model. However, protonating the quinoxalyl-dithiolene model induces pyran cyclization forming an unstable, pyrano-quinoxalyl-dithiolene complex which subsequently dehydrates and rearranges to a pyrrolo-quinoxlyl-dithiolene complex that was previously characterized. The protonated pyrano-quinoxalyl-dithiolene complex was characterized by absorption spectroscopy and cyclic voltammetry, and these results suggest pyran cyclization leads to a significant change in the Mo electronic structure exhibited as a strong intraligand charge transfer (ILCT) transition and 370 mV positive shift of the Mo(V/IV) reduction potential. The influence of protonation on quinoxaline reactivity supports the hypothesis that the local protein environment in the second coordination sphere of molybdenum cofactor (Moco) could control pyran cyclization. The results also demonstrate that the remarkable chemical reactivity of the pterin-dithiolene ligand is subtly distinct and not reproduced by the simpler quinoxaline analog that is often used to replace pterin in synthetic Moco models.
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Affiliation(s)
- Douglas R. Gisewhite
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Alexandra L. Nagelski
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Daniel C. Cummins
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Glenn P. A. Yap
- Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware 19716, United States
| | - Sharon J. N. Burgmayer
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
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12
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Gisewhite DR, Yang J, Williams BR, Esmail A, Stein B, Kirk ML, Burgmayer SJN. Implications of Pyran Cyclization and Pterin Conformation on Oxidized Forms of the Molybdenum Cofactor. J Am Chem Soc 2018; 140:12808-12818. [PMID: 30200760 DOI: 10.1021/jacs.8b05777] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The large family of mononuclear molybdenum and tungsten enzymes all possess the special ligand molybdopterin (MPT), which consists of a metal-binding dithiolene chelate covalently bound to a pyranopterin group. MPT pyran cyclization/scission processes have been proposed to modulate the reactivity of the metal center during catalysis. We have designed several small-molecule models for the Mo-MPT cofactor that allow detailed investigation into how pyran cyclization modulates electronic communication between the dithiolene and pterin moieties and how this cyclization alters the electronic environment of the molybdenum catalytic site. Using a combination of cyclic voltammetry, vibrational spectroscopy (FT-IR and rR), electronic absorption spectroscopy, and X-ray absorption spectroscopy, distinct changes in the Mo≡O stretching frequency, Mo(V/IV) reduction potential, and electronic structure across the pterin-dithiolene ligand are observed as a function of pyran ring closure. The results are significant, for they reveal that a dihydropyranopterin is electronically coupled into the Mo-dithiolene group due to a coplanar conformation of the pterin and dithiolene units, providing a mechanism for the electron-deficient pterin to modulate the Mo environment. A spectroscopic signature identified for the dihydropyranopterin-dithiolene ligand on Mo is a strong dithiolene → pterin charge transfer transition. In the absence of a pyran group bridge between pterin and dithiolene, the pterin rotates out of plane, largely decoupling the system. The results support a hypothesis that pyran cyclization/scission processes in MPT may function as a molecular switch to electronically couple and decouple the pterin and dithiolene to adjust the redox properties in certain pyranopterin molybdenum enzymes.
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Affiliation(s)
- Douglas R Gisewhite
- Department of Chemistry , Bryn Mawr College , Bryn Mawr , Pennsylvania 19010 , United States
| | - Jing Yang
- Department of Chemistry and Chemical Biology , The University of New Mexico , MSC03 2060, 1 University of New Mexico , Albuquerque , New Mexico 87131-0001 , United States
| | - Benjamin R Williams
- Department of Chemistry , Bryn Mawr College , Bryn Mawr , Pennsylvania 19010 , United States
| | - Alisha Esmail
- Department of Chemistry , Bryn Mawr College , Bryn Mawr , Pennsylvania 19010 , United States
| | - Benjamin Stein
- Department of Chemistry and Chemical Biology , The University of New Mexico , MSC03 2060, 1 University of New Mexico , Albuquerque , New Mexico 87131-0001 , United States
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology , The University of New Mexico , MSC03 2060, 1 University of New Mexico , Albuquerque , New Mexico 87131-0001 , United States
| | - Sharon J N Burgmayer
- Department of Chemistry , Bryn Mawr College , Bryn Mawr , Pennsylvania 19010 , United States
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13
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Wang SY, Dong X, Zhou ZH. N-hetercycle dimeric molybdenum(V) complexes with strong interactions and their catalytic degradations of methyl orange. Inorganica Chim Acta 2018. [DOI: 10.1016/j.ica.2018.03.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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14
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Bose M, Moula G, Begum A, Sarkar S. Synthesis and characterization of cyano and isocyano complexes of bis(dithiolato) molybdenum using Me3SiCN: a route to a cyanide-bridged multimer to a monomer. NEW J CHEM 2018. [DOI: 10.1039/c8nj00246k] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The Mo(iv) bis (dithiolate) complex showed diverse reactions with Me3SiCN in the presence and absence of a coligand and under protic and aprotic media.
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Affiliation(s)
- Moumita Bose
- Department of Chemistry
- Indian Institute of Technology Kanpur
- Kanpur-208016
- India
| | - Golam Moula
- Department of Chemistry
- Indian Institute of Technology Kanpur
- Kanpur-208016
- India
| | - Ameerunisha Begum
- Department of Chemistry
- Indian Institute of Technology Kanpur
- Kanpur-208016
- India
| | - Sabyasachi Sarkar
- Nanoscience and Synthetic Leaf Laboratory at Downing Hall
- Centre for Healthcare Science and Technology
- Indian Institute of Engineering Science and Technology-Shibpur
- Botanic Garden
- Howrah 711103
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15
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Maiti BK, Almeida RM, Moura I, Moura JJ. Rubredoxins derivatives: Simple sulphur-rich coordination metal sites and its relevance for biology and chemistry. Coord Chem Rev 2017. [DOI: 10.1016/j.ccr.2017.10.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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16
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Dong C, Yang J, Reschke S, Leimkühler S, Kirk ML. Vibrational Probes of Molybdenum Cofactor-Protein Interactions in Xanthine Dehydrogenase. Inorg Chem 2017; 56:6830-6837. [PMID: 28590138 DOI: 10.1021/acs.inorgchem.7b00028] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The pyranopterin dithiolene (PDT) ligand is an integral component of the molybdenum cofactor (Moco) found in all molybdoenzymes with the sole exception of nitrogenase. However, the roles of the PDT in catalysis are still unknown. The PDT is believed to be bound to the proteins by an extensive hydrogen-bonding network, and it has been suggested that these interactions may function to fine-tune Moco for electron- and atom-transfer reactivity in catalysis. Here, we use resonance Raman (rR) spectroscopy to probe Moco-protein interactions using heavy-atom congeners of lumazine, molecules that bind tightly to both wild-type xanthine dehydrogenase (wt-XDH) and its Q102G and Q197A variants following enzymatic hydroxylation to the corresponding violapterin product molecules. The resulting enzyme-product complexes possess intense near-IR absorption, allowing high-quality rR spectra to be collected on wt-XDH and the Q102G and Q197A variants. Small negative frequency shifts relative to wt-XDH are observed for the low-frequency Moco vibrations. These results are interpreted in the context of weak hydrogen-bonding and/or electrostatic interactions between Q102 and the -NH2 terminus of the PDT, and between Q197 and the terminal oxo of the Mo≡O group. The Q102A, Q102G, Q197A, and Q197E variants do not appreciably affect the kinetic parameters kred and kred/KD, indicating that a primary role for these glutamine residues is to stabilize and coordinate Moco in the active site of XO family enzymes but to not directly affect the catalytic throughput. Raman frequency shifts between wt-XDH and its Q102G variant suggest that the changes in the electron density at the Mo ion that accompany Mo oxidation during electron-transfer regeneration of the catalytically competent active site are manifest in distortions at the distant PDT amino terminus. This implies a primary role for the PDT as a conduit for facilitating enzymatic electron-transfer reactivity in xanthine oxidase family enzymes.
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Affiliation(s)
- Chao Dong
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Stefan Reschke
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam , 14476 Potsdam, Germany
| | - Silke Leimkühler
- Institute of Biochemistry and Biology, Department of Molecular Enzymology, University of Potsdam , 14476 Potsdam, Germany
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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Ghosh P, Banerjee S, Lahiri GK. Ruthenium Derivatives of in Situ Generated Redox-Active 1,2-Dinitrosobenzene and 2-Nitrosoanilido. Diverse Structural and Electronic Forms. Inorg Chem 2016; 55:12832-12843. [DOI: 10.1021/acs.inorgchem.6b02197] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Prabir Ghosh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Soumyodip Banerjee
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Goutam Kumar Lahiri
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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18
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Affiliation(s)
- Charles G. Young
- Department of Chemistry and PhysicsLa Trobe Institute for Molecular ScienceLa Trobe University3086MelbourneVictoriaAustralia
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19
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Yang J, Mogesa B, Basu P, Kirk ML. Large Ligand Folding Distortion in an Oxomolybdenum Donor-Acceptor Complex. Inorg Chem 2015; 55:785-93. [PMID: 26692422 DOI: 10.1021/acs.inorgchem.5b02252] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Interligand charge transfer is examined in the novel metallo-dithiolene complex MoO(SPh)2((i)Pr2Dt(0)) (where (i)Pr2Dt(0) = N,N'-isopropyl-piperazine-2,3-dithione). The title complex displays a remarkable 70° "envelope"-type fold of the five-membered dithiolene ring, which is bent upward toward the terminal oxo ligand. A combination of electronic absorption and resonance Raman spectroscopies have been used to probe the basic electronic structure responsible for the large fold-angle distortion. The intense charge transfer transition observed at ∼18 000 cm(-1) is assigned as a thiolate → dithione ligand-to-ligand charge transfer (LL'CT) transition that also possesses Mo(IV) → dithione charge transfer character. Strong orbital mixing between occupied and virtual orbitals with Mo(x(2)-y(2)) orbital character is derived from a strong pseudo Jahn-Teller effect, which drives the large fold-angle distortion to yield a double-well potential in the electronic ground state.
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Affiliation(s)
- Jing Yang
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
| | - Benjamin Mogesa
- Department of Chemistry and Biochemistry, Duquesne University , Pittsburgh, Pennsylvania 15282, United States
| | - Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University , Pittsburgh, Pennsylvania 15282, United States
| | - Martin L Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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20
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Wu SY, Rothery RA, Weiner JH. Pyranopterin Coordination Controls Molybdenum Electrochemistry in Escherichia coli Nitrate Reductase. J Biol Chem 2015; 290:25164-73. [PMID: 26297003 DOI: 10.1074/jbc.m115.665422] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Indexed: 11/06/2022] Open
Abstract
We test the hypothesis that pyranopterin (PPT) coordination plays a critical role in defining molybdenum active site redox chemistry and reactivity in the mononuclear molybdoenzymes. The molybdenum atom of Escherichia coli nitrate reductase A (NarGHI) is coordinated by two PPT-dithiolene chelates that are defined as proximal and distal based on their proximity to a [4Fe-4S] cluster known as FS0. We examined variants of two sets of residues involved in PPT coordination: (i) those interacting directly or indirectly with the pyran oxygen of the bicyclic distal PPT (NarG-Ser(719), NarG-His(1163), and NarG-His(1184)); and (ii) those involved in bridging the two PPTs and stabilizing the oxidation state of the proximal PPT (NarG-His(1092) and NarG-His(1098)). A S719A variant has essentially no effect on the overall Mo(VI/IV) reduction potential, whereas the H1163A and H1184A variants elicit large effects (ΔEm values of -88 and -36 mV, respectively). Ala variants of His(1092) and His(1098) also elicit large ΔEm values of -143 and -101 mV, respectively. An Arg variant of His(1092) elicits a small ΔEm of +18 mV on the Mo(VI/IV) reduction potential. There is a linear correlation between the molybdenum Em value and both enzyme activity and the ability to support anaerobic respiratory growth on nitrate. These data support a non-innocent role for the PPT moieties in controlling active site metal redox chemistry and catalysis.
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Affiliation(s)
- Sheng-Yi Wu
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Richard A Rothery
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Joel H Weiner
- From the Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
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21
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Williams BR, Gisewhite D, Kalinsky A, Esmail A, Burgmayer SJN. Solvent-Dependent Pyranopterin Cyclization in Molybdenum Cofactor Model Complexes. Inorg Chem 2015; 54:8214-22. [PMID: 25942001 DOI: 10.1021/acs.inorgchem.5b00532] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The conserved pterin dithiolene ligand that coordinates molybdenum (Mo) in the cofactor (Moco) of mononuclear Mo enzymes can exist in both a tricyclic pyranopterin dithiolene form and as a bicyclic pterin-dithiolene form as observed in protein crystal structures of several bacterial molybdoenzymes. Interconversion between the tricyclic and bicyclic forms via pyran scission and cyclization has been hypothesized to play a role in the catalytic mechanism of Moco. Therefore, understanding the interconversion between the tricyclic and bicyclic forms, a type of ring-chain tautomerism, is an important aspect of study to understand its role in catalysis. In this study, equilibrium constants (K(eq)) as well as enthalpy, entropy, and free energy values are obtained for pyran ring tautomerism exhibited by two Moco model complexes, namely, (Et4N)[Tp*Mo(O)(S2BMOPP)] (1) and (Et4N)[Tp*Mo(O)(S2PEOPP)] (2), as a solvent-dependent equilibrium process. Keq values obtained from (1)H NMR data in seven deuterated solvents show a correlation between solvent polarity and tautomer form, where solvents with higher polarity parameters favor the pyran form.
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Affiliation(s)
- Benjamin R Williams
- Department of Chemistry, Bryn Mawr College , Bryn Mawr, Pennsylvania 19010, United States
| | - Douglas Gisewhite
- Department of Chemistry, Bryn Mawr College , Bryn Mawr, Pennsylvania 19010, United States
| | - Anna Kalinsky
- Department of Chemistry, Bryn Mawr College , Bryn Mawr, Pennsylvania 19010, United States
| | - Alisha Esmail
- Department of Chemistry, Bryn Mawr College , Bryn Mawr, Pennsylvania 19010, United States
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22
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Basu P, Nieter Burgmayer SJ. Recent developments in the study of molybdoenzyme models. J Biol Inorg Chem 2015; 20:373-83. [PMID: 25578808 PMCID: PMC4336637 DOI: 10.1007/s00775-014-1228-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 12/07/2014] [Indexed: 12/22/2022]
Abstract
Over the past two decades, a plethora of crystal structures of molybdenum enzymes has appeared in the literature providing a clearer picture of the enzymatic active sites and increasing the challenge to chemists to develop accurate models for those sites. In this minireview we discuss the most recent model studies aimed to reproduce detailed features of the pterin-dithiolene ligand, both as the uncoordinated form and as a chelate coordinated to molybdenum.
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Affiliation(s)
- Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282
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23
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Rothery RA, Weiner JH. Shifting the metallocentric molybdoenzyme paradigm: the importance of pyranopterin coordination. J Biol Inorg Chem 2014; 20:349-72. [PMID: 25267303 DOI: 10.1007/s00775-014-1194-6] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 09/15/2014] [Indexed: 01/10/2023]
Abstract
In this review, we test the hypothesis that pyranopterin coordination plays a critical role in defining substrate reactivities in the four families of mononuclear molybdenum and tungsten enzymes (Mo/W-enzymes). Enzyme families containing a single pyranopterin dithiolene chelate have been demonstrated to have reactivity towards two (sulfite oxidase, SUOX-fold) and five (xanthine dehydrogenase, XDH-fold) types of substrate, whereas the major family of enzymes containing a bis-pyranopterin dithiolene chelate (dimethylsulfoxide reductase, DMSOR-fold) is reactive towards eight types of substrate. A second bis-pyranopterin enzyme (aldehyde oxidoreductase, AOR-fold) family catalyzes a single type of reaction. The diversity of reactions catalyzed by each family correlates with active site variability, and also with the number of pyranopterins and their coordination by the protein. In the case of the AOR-fold enzymes, inflexibility of pyranopterin coordination correlates with their limited substrate specificity (oxidation of aldehydes). In examples of the SUOX-fold and DMSOR-fold enzymes, we observe three types of histidine-containing charge-transfer relays that can: (1) connect the piperazine ring of the pyranopterin to the substrate-binding site (SUOX-fold enzymes); (2) provide inter-pyranopterin communication (DMSOR-fold enzymes); and (3) connect a pyran ring oxygen to deeply buried water molecules (the DMSOR-fold NarGHI-type nitrate reductases). Finally, sequence data mining reveals a number of bacterial species whose predicted proteomes contain large numbers (up to 64) of Mo/W-enzymes, with the DMSOR-fold enzymes being dominant. These analyses also reveal an inverse correlation between Mo/W-enzyme content and pathogenicity.
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Affiliation(s)
- Richard A Rothery
- Department of Biochemistry, University of Alberta, Edmonton, AB, T6G 2H7, Canada
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24
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Dong C, Yang J, Leimkühler S, Kirk ML. Pyranopterin dithiolene distortions relevant to electron transfer in xanthine oxidase/dehydrogenase. Inorg Chem 2014; 53:7077-9. [PMID: 24979205 PMCID: PMC4215880 DOI: 10.1021/ic500873y] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The reducing substrates 4-thiolumazine and 2,4-dithiolumazine have been used to form Mo(IV)-product complexes with xanthine oxidase (XO) and xanthine dehydrogenase. These Mo(IV)-product complexes display an intense metal-to-ligand charge-transfer (MLCT) band in the near-infrared region of the spectrum. Optical pumping into this MLCT band yields resonance Raman spectra of the Mo site that are devoid of contributions from the highly absorbing FAD and 2Fe2S clusters in the protein. The resonance Raman spectra reveal in-plane bending modes of the bound product and low-frequency molybdenum dithiolene and pyranopterin dithiolene vibrational modes. This work provides keen insight into the role of the pyranopterin dithiolene in electron-transfer reactivity.
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Affiliation(s)
- Chao Dong
- Department of Chemistry and Chemical Biology, The University of New Mexico , MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131-0001, United States
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25
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Hilken S, Kaletta F, Heinsch A, Neudörfl JM, Berkessel A. Synthesis of an Oxidation-Stable Analogue of Cyclic Pyranopterin Monophosphate (cPMP). European J Org Chem 2014. [DOI: 10.1002/ejoc.201301784] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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26
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Williams BR, Fu Y, Yap GPA, Burgmayer SJN. Structure and reversible pyran formation in molybdenum pyranopterin dithiolene models of the molybdenum cofactor. J Am Chem Soc 2012; 134:19584-7. [PMID: 23157708 DOI: 10.1021/ja310018e] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The syntheses and X-ray structures of two molybdenum pyranopterin dithiolene complexes in biologically relevant Mo(4+) and Mo(5+) states are reported. Crystallography reveals that these complexes possess a pyran ring formed through a spontaneous cyclization reaction of a dithiolene side-chain hydroxyl group at a C═N bond of the pterin. NMR data on the Mo(4+) complex suggest that a reversible pyran ring cyclization occurs in solution. These results provide experimental evidence that the pyranopterin dithiolene ligand in molybdenum and tungsten enzymes could participate in catalysis through dynamic processes modulated by the protein.
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Affiliation(s)
- Benjamin R Williams
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010-2899, United States
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27
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Okamura TA, Tatsumi M, Omi Y, Yamamoto H, Onitsuka K. Selective and effective stabilization of Mo(VI)═O bonds by NH···S hydrogen bonds via trans influence. Inorg Chem 2012; 51:11688-97. [PMID: 23075211 DOI: 10.1021/ic301597d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A monooxomolybdenum(IV) complex containing two intramolecular NH···S hydrogen bonds, (NEt(4))(2)[Mo(IV)O(1,2-S(2)-3-t-BuNHCOC(6)H(3))(2)], was synthesized. The trans isomer was crystallized as the major product, and the molecular structure was determined by X-ray analysis. The trans isomer was isomerized by heating in solution to give a 1:1 mixture of trans and cis isomers. Oxidation of these isomers by Me(3)NO afforded (NEt(4))(2)[Mo(VI)O(2)(1,2-S(2)-3-t-BuNHCOC(6)H(3))(2)]. (1)H NMR analysis revealed that the dioxomolybdenum(VI) complex existed as a single isomer where both oxo ligands were trans to each of the two hydrogen-bonded thiolate ligands. The Mo(VI)═O bond was effectively stabilized by the NH···S hydrogen bond via trans influence, which was determined using resonance Raman spectroscopy. These results were supported by preliminary density functional theory calculations.
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Affiliation(s)
- Taka-aki Okamura
- Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan.
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28
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Pyranopterin conformation defines the function of molybdenum and tungsten enzymes. Proc Natl Acad Sci U S A 2012; 109:14773-8. [PMID: 22927383 DOI: 10.1073/pnas.1200671109] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have analyzed the conformations of 319 pyranopterins in 102 protein structures of mononuclear molybdenum and tungsten enzymes. These span a continuum between geometries anticipated for quinonoid dihydro, tetrahydro, and dihydro oxidation states. We demonstrate that pyranopterin conformation is correlated with the protein folds defining the three major mononuclear molybdenum and tungsten enzyme families, and that binding-site micro-tuning controls pyranopterin oxidation state. Enzymes belonging to the bacterial dimethyl sulfoxide reductase (DMSOR) family contain a metal-bis-pyranopterin cofactor, the two pyranopterins of which have distinct conformations, with one similar to the predicted tetrahydro form, and the other similar to the predicted dihydro form. Enzymes containing a single pyranopterin belong to either the xanthine dehydrogenase (XDH) or sulfite oxidase (SUOX) families, and these have pyranopterin conformations similar to those predicted for tetrahydro and dihydro forms, respectively. This work provides keen insight into the roles of pyranopterin conformation and oxidation state in catalysis, redox potential modulation of the metal site, and catalytic function.
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29
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Matsushita O, Derkacheva VM, Muranaka A, Shimizu S, Uchiyama M, Luk’yanets EA, Kobayashi N. Rectangular-Shaped Expanded Phthalocyanines with Two Central Metal Atoms. J Am Chem Soc 2012; 134:3411-8. [DOI: 10.1021/ja209589x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Osamu Matsushita
- Department of Chemistry, Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan
| | | | - Atsuya Muranaka
- Advanced Elements
Chemistry Research
Team, ASI, RIKEN, Wako 351-0198, Japan
- PRESTO, Japan Science and Technology Agency (JST), Saitama 332-0012, Japan
| | - Soji Shimizu
- Department of Chemistry, Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan
| | - Masanobu Uchiyama
- Advanced Elements
Chemistry Research
Team, ASI, RIKEN, Wako 351-0198, Japan
- Graduate School of Pharmaceutical
Sciences, The University of Tokyo, Bunkyo-ku,
Tokyo 113-0033, Japan
| | - Evgeny A. Luk’yanets
- Organic Intermediates and Dyes Institute, B. Sadovaya 1/4, Moscow 123995,
Russia
| | - Nagao Kobayashi
- Department of Chemistry, Graduate
School of Science, Tohoku University, Sendai
980-8578, Japan
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30
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Liu Y, Liu CG, Sun SL, Yang GC, Qiu YQ. Redox-switching second-order nonlinear optical responses of N^N^N ruthenium complexes. COMPUT THEOR CHEM 2012. [DOI: 10.1016/j.comptc.2011.10.025] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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31
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Mtei RP, Perera E, Mogesa B, Stein B, Basu P, Kirk ML. A Valence Bond Description of Dizwitterionic Dithiolene Character in an Oxomolybdenum-bis(dithione). Eur J Inorg Chem 2011; 2011:5467-5470. [PMID: 23956683 DOI: 10.1002/ejic.201101084] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Metallo-dithiolene non-innocence is explored in an oxomolybdenum-bis(dithione) complex, [Mo4+O(i-Pr2Pipdt)2Cl][PF6] (where i-Pr2Pipdt is N,N'-piperazine-2,3-dithione), that possesses a piperazine ring as an integral part of the dithiolene ligand. The title complex displays unusual spectroscopic features for a formally reduced Mo(IV) dithiolene complex, namely a low energy metal-to-ligand charge transfer band with appreciable intensity and C-C and C-S stretching frequencies that are markedly different from those of oxomolydenum complexes coordinated to dianionic dithiolene ligands. The electronic structure of the ligand has been described in valence bond terms as a resonance hybrid of dithione and dizwitterionic dithiolene contributing structures.
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Affiliation(s)
- Regina P Mtei
- Department of Chemistry and Chemical Biology, The Univesity of New Mexico, MSC03 2060. 1 University of New Mexico, Albuquerque, NM 87131-0001
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Matz KG, Mte RP, Rothstein R, Kirk ML, Nieter Burgmayer SJ. Study of molybdenum(4+) quinoxalyldithiolenes as models for the noninnocent pyranopterin in the molybdenum cofactor. Inorg Chem 2011; 50:9804-15. [PMID: 21894968 PMCID: PMC3268461 DOI: 10.1021/ic200783a] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
A model system for the molybdenum cofactor has been developed that illustrates the noninnocent behavior of an N-heterocycle appended to a dithiolene chelate on molybdenum. The pyranopterin of the molybdenum cofactor is modeled by a quinoxalyldithiolene ligand (S(2)BMOQO) formed from the reaction of molybdenum tetrasulfide and quinoxalylalkyne. The resulting complexes TEA[Tp*MoX(S(2)BMOQO)] [1, X = S; 3, X = O; TEA = tetraethylammonium; Tp* = hydrotris(3,5-dimethylpyrazolyl)borate] undergo a dehydration-driven intramolecular cyclization within quinoxalyldithiolene, forming Tp*MoX(pyrrolo-S(2)BMOQO) (2, X = S; 4, X = O). 4 can be oxidized by one electron to produce the molybdenum(5+) complex 5. In a preliminary report of this work, evidence from X-ray crystallography, electronic absorption and resonance Raman spectroscopies, and density functional theory (DFT) bonding calculations revealed that 4 possesses an unusual asymmetric dithiolene chelate with significant thione-thiolate character. The results described here provide a detailed description of the reaction conditions that lead to the formation of 4. Data from cyclic voltammetry, additional DFT calculations, and several spectroscopic methods (IR, electronic absorption, resonance Raman, and electron paramagnetic resonance) have been used to characterize the properties of members in this suite of five Mo(S(2)BMOQO) complexes and further substantiate the highly electron-withdrawing character of the pyrrolo-S(2)BMOQO ligand in 2, 4, and 5. This study of the unique noninnocent ligand S(2)BMOQO provides examples of the roles that the N-heterocycle pterin can play as an essential part of the molybdenum cofactor. The versatile nature of a dithiolene appended by heterocycles may aid in modulating the redox processes of the molybdenum center during the course of enzyme catalysis.
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Affiliation(s)
- Kelly G. Matz
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010
| | - Regina P. Mte
- Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, New Mexico 87131-0001
| | - Rebecca Rothstein
- Department of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010
| | - Martin L. Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, Albuquerque, New Mexico 87131-0001
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Abstract
The molybdenum cofactor is composed of a molybdenum coordinated by one or two rather complicated ligands known as either molybdopterin or pyranopterin. Pterin is one of a large family of bicyclic N-heterocycles called pteridines. Such molecules are widely found in Nature, having various forms to perform a variety of biological functions. This article describes the basic nomenclature of pterin, their biological roles, structure, chemical synthesis and redox reactivity. In addition, the biosynthesis of pterins and current models of the molybdenum cofactor are discussed.
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Affiliation(s)
- Partha Basu
- Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA 15282, United States
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Sugimoto H, Tano H, Suyama K, Kobayashi T, Miyake H, Itoh S, Mtei RP, Kirk ML. Chalcogenidobis(ene-1,2-dithiolate)molybdenum(IV) complexes (chalcogenide E = O, S, Se): probing Mo≡E and ene-1,2-dithiolate substituent effects on geometric and electronic structure. Dalton Trans 2011; 40:1119-31. [PMID: 21165484 PMCID: PMC3168557 DOI: 10.1039/c0dt00871k] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
New square-pyramidal bis(ene-1,2-dithiolate)MoSe complexes, [Mo(IV)Se(L)(2)](2-), have been synthesised along with their terminal sulfido analogues, [Mo(IV)S(L)(2)](2-), using alkyl (L(C(4)H(8))), phenyl (L(Ph)) and methyl carboxylate (L(COOMe)) substituted dithiolene ligands (L). These complexes now complete three sets of Mo(IV)O, Mo(IV)S and Mo(IV)Se species that are coordinated with identical ene-1,2-dithiolate ligands. The [alkyl substituted Mo(S/Se)(L(C(4)H(8)))(2)](2-) complexes were reported in prior investigations (H. Sugimoto, T. Sakurai, H. Miyake, K. Tanaka and H. Tsukube, Inorg. Chem. 2005, 44, 6927, H. Tano, R. Tajima, H. Miyake, S. Itoh and H. Sugimoto, Inorg. Chem. 2008, 47, 7465). The new series of complexes enable a systematic investigation of terminal chalcogenido and supporting ene-1,2-dithiolate ligand effects on geometric structure, electronic structure, and spectroscopic properties. X-ray crystallographic analysis of these (Et(4)N)(2)[MoEL(2)] (E = terminal chalocogenide) complexes reveals an isostructural Mo centre that adopts a distorted square pyramidal geometry. The M≡E bond distances observed in the crystal structures and the ν(M≡E) vibrational frequencies indicate that these bonds are weakened with an increase in L→Mo electron donation (L(COOMe) < L(Ph) < L(C(4)H(8))), and this order is confirmed by an electrochemical study of the complexes. The (77)Se NMR resonances in MoSeL complexes appear at lower magnetic fields as the selenido ion became less basic from MoSeL(C(4)H(8)), MoSeL(Ph) and MoSeL(COOMe). Electronic absorption and resonance Raman spectroscopies have been used to assign key ligand-field, MLCT, LMCT and intraligand CT bands in complexes that possess the L(COOMe) ligand. The presence of low-energy intraligand CT transition in these MoEL(COOMe) compounds directly probes the electron withdrawing nature of the -COOMe substituents, and this underscores the complex electronic structure of square pyramidal bis(ene-1,2-dithiolate)-Mo(IV) complexes that possess extended dithiolene conjugation.
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Affiliation(s)
- Hideki Sugimoto
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871Japan
| | - Hiroyuki Tano
- Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Koichiro Suyama
- Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Tomoya Kobayashi
- Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Hiroyuki Miyake
- Department of Chemistry, Graduate School of Science, Osaka City University, 3-3-138 Sumiyoshi-ku, Osaka 558-8585, Japan
| | - Shinobu Itoh
- Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871Japan
| | - Regina P. Mtei
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131–0001, USA
| | - Martin L. Kirk
- Department of Chemistry and Chemical Biology, The University of New Mexico, MSC03 2060, 1 University of New Mexico, Albuquerque, New Mexico 87131–0001, USA
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Nomura M. Organometallic dithiolene complexes of the group 8–10 metals: Reactivities, structures and electrochemical behavior. Dalton Trans 2011; 40:2112-40. [DOI: 10.1039/c0dt01025a] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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