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Devkota L, SantaLucia DJ, Wheaton AM, Pienkos AJ, Lindeman SV, Krzystek J, Ozerov M, Berry JF, Telser J, Fiedler AT. Spectroscopic and Magnetic Studies of Co(II) Scorpionate Complexes: Is There a Halide Effect on Magnetic Anisotropy? Inorg Chem 2023; 62:5984-6002. [PMID: 37000941 DOI: 10.1021/acs.inorgchem.2c04468] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/03/2023]
Abstract
The observation of single-molecule magnetism in transition-metal complexes relies on the phenomenon of zero-field splitting (ZFS), which arises from the interplay of spin-orbit coupling (SOC) with ligand-field-induced symmetry lowering. Previous studies have demonstrated that the magnitude of ZFS in complexes with 3d metal ions is sometimes enhanced through coordination with heavy halide ligands (Br and I) that possess large free-atom SOC constants. In this study, we systematically probe this "heavy-atom effect" in high-spin cobalt(II)-halide complexes supported by substituted hydrotris(pyrazol-1-yl)borate ligands (TptBu,Me and TpPh,Me). Two series of complexes were prepared: [CoIIX(TptBu,Me)] (1-X; X = F, Cl, Br, and I) and [CoIIX(TpPh,Me)(HpzPh,Me)] (2-X; X = Cl, Br, and I), where HpzPh,Me is a monodentate pyrazole ligand. Examination with dc magnetometry, high-frequency and -field electron paramagnetic resonance, and far-infrared magnetic spectroscopy yielded axial (D) and rhombic (E) ZFS parameters for each complex. With the exception of 1-F, complexes in the four-coordinate 1-X series exhibit positive D-values between 10 and 13 cm-1, with no dependence on halide size. The five-coordinate 2-X series exhibit large and negative D-values between -60 and -90 cm-1. Interpretation of the magnetic parameters with the aid of ligand-field theory and ab initio calculations elucidated the roles of molecular geometry, ligand-field effects, and metal-ligand covalency in controlling the magnitude of ZFS in cobalt-halide complexes.
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Ferentinos E, Tzeli D, Sottini S, Groenen EJJ, Ozerov M, Poneti G, Kaniewska-Laskowska K, Krzystek J, Kyritsis P. Magnetic anisotropy and structural flexibility in the field-induced single ion magnets [Co{(OPPh 2)(EPPh 2)N} 2], E = S, Se, explored by experimental and computational methods. Dalton Trans 2023; 52:2036-2050. [PMID: 36692040 PMCID: PMC9926333 DOI: 10.1039/d2dt03335f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Accepted: 01/14/2023] [Indexed: 01/25/2023]
Abstract
During the last few years, a large number of mononuclear Co(II) complexes of various coordination geometries have been explored as potential single ion magnets (SIMs). In the work presented herein, the Co(II) S = 3/2 tetrahedral [Co{(OPPh2)(EPPh2)N}2], E = S, Se, complexes (abbreviated as CoO2E2), bearing chalcogenated mixed donor-atom imidodiphosphinato ligands, were studied by both experimental and computational techniques. Specifically, direct current (DC) magnetometry provided estimations of their zero-field splitting (zfs) axial (D) and rhombic (E) parameter values, which were more accurately determined by a combination of far-infrared magnetic spectroscopy and high-frequency and -field EPR spectroscopy studies. The latter combination of techniques was also implemented for the S = 3/2 tetrahedral [Co{(EPiPr2)2N}2], E = S, Se, complexes, confirming the previously determined magnitude of their zfs parameters. For both pairs of complexes (E = S, Se), it is concluded that the identity of the E donor atom does not significantly affect their zfs parameters. High-resolution multifrequency EPR studies of CoO2E2 provided evidence of multiple conformations, which are more clearly observed for CoO2Se2, in agreement with the structural disorder previously established for this complex by X-ray crystallography. The CoO2E2 complexes were shown to be field-induced SIMs, i.e., they exhibit slow relaxation of magnetization in the presence of an external DC magnetic field. Advanced quantum-chemical calculations on CoO2E2 provided additional insight into their electronic and structural properties.
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Affiliation(s)
- Eleftherios Ferentinos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece.
| | - Demeter Tzeli
- Physical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece
- Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48 Vassileos Constantinou Ave., GR-11635 Athens, Greece
| | - Silvia Sottini
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Edgar J J Groenen
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden University, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
| | - Mykhaylo Ozerov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
| | - Giordano Poneti
- Instituto de Química, Universidade Federal do Rio de Janeiro, 21941-909 Rio de Janeiro, Brazil.
| | - Kinga Kaniewska-Laskowska
- Department of Inorganic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, G. Narutowicza St. 11/12, Gdańsk PL-80-233, Poland
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, USA.
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, GR-15771 Athens, Greece.
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Stoian SA, Moshari M, Ferentinos E, Grigoropoulos A, Krzystek J, Telser J, Kyritsis P. Electronic Structure of Tetrahedral, S = 2, [Fe{(EP iPr 2) 2N} 2], E = S, Se, Complexes: Investigation by High-Frequency and -Field Electron Paramagnetic Resonance, 57Fe Mössbauer Spectroscopy, and Quantum Chemical Studies. Inorg Chem 2021; 60:10990-11005. [PMID: 34288665 DOI: 10.1021/acs.inorgchem.1c00670] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we assessed the electronic structures of two pseudotetrahedral complexes of FeII, [Fe{(SPiPr2)2N}2] (1) and [Fe{(SePiPr2)2N}2] (2), using high-frequency and -field EPR (HFEPR) and field-dependent 57Fe Mössbauer spectroscopies. This investigation revealed S = 2 ground states characterized by moderate, negative zero-field splitting (zfs) parameters D. The crystal-field (CF) theory analysis of the spin Hamiltonian (sH) and hyperfine structure parameters revealed that the orbital ground states of 1 and 2 have a predominant dx2-y2 character, which is admixed with dz2 (∼10%). Although replacing the S-containing ligands of 1 by their Se-containing analogues in 2 leads to a smaller |D| value, our theoretical analysis, which relied on extensive ab initio CASSCF calculations, suggests that the ligand spin-orbit coupling (SOC) plays a marginal role in determining the magnetic anisotropy of these compounds. Instead, the dx2-y2β → dxyβ excitations yield a large negative contribution, which dominates the zfs of both 1 and 2, while the different energies of the dx2-y2β → dxzβ transitions are the predominant factor responsible for the difference in zfs between 1 and 2. The electronic structures of these compounds are contrasted with those of other [FeS4] sites, including reduced rubredoxin by considering a D2-type distortion of the [Fe(E-X)4] cores, where E = S, Se; X = C, P. Our combined CASSCF/DFT calculations indicate that while the character of the orbital ground state and the quintet excited states' contribution to the zfs of 1 and 2 are modulated by the magnitude of the D2 distortion, this structural change does not impact the contribution of the excited triplet states.
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Affiliation(s)
- Sebastian A Stoian
- Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
| | - Mahsa Moshari
- Department of Chemistry, University of Idaho, Moscow, Idaho 83844, United States
| | - Eleftherios Ferentinos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15771 Athens, Greece
| | - Alexios Grigoropoulos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15771 Athens, Greece
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Joshua Telser
- Department of Biological, Physical, and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, Zografou, 15771 Athens, Greece
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Gompa TP, Greer SM, Rice NT, Jiang N, Telser J, Ozarowski A, Stein BW, La Pierre HS. High-Frequency and -Field Electron Paramagnetic Resonance Spectroscopic Analysis of Metal-Ligand Covalency in a 4f 7 Valence Series (Eu 2+, Gd 3+, and Tb 4+). Inorg Chem 2021; 60:9064-9073. [PMID: 34106710 DOI: 10.1021/acs.inorgchem.1c01062] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
The recent isolation of molecular tetravalent lanthanide complexes has enabled renewed exploration of the effect of oxidation state on the single-ion properties of the lanthanide ions. Despite the isotropic nature of the 8S ground state in a tetravalent terbium complex, [Tb(NP(1,2-bis-tBu-diamidoethane)(NEt2))4], preliminary X-band electron paramagnetic resonance (EPR) measurements on tetravalent terbium complexes show rich spectra with broad resonances. The complexity of these spectra highlights the limits of conventional X-band EPR for even qualitative determination of zero-field splitting (ZFS) in these complexes. Therefore, we report the synthesis and characterization of a novel valence series of 4f7 molecular complexes spanning three oxidation states (Eu2+, Gd3+, and Tb4+) featuring a weak-field imidophosphorane ligand system, and employ high-frequency and -field electron paramagnetic resonance (HFEPR) to obtain quantitative values for ZFS across this valence series. The series was designed to minimize deviation in the first coordination sphere from the pseudotetrahedral geometry in order to directly interrogate the role of metal identity and charge on the complexes' electronic structures. These HFEPR studies are supported by crystallographic analysis and quantum-chemical calculations to assess the relative covalent interactions in each member of this valence series and the effect of the oxidation state on the splitting of the ground state and first excited state.
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Affiliation(s)
| | - Samuel M Greer
- Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, United States
| | | | | | - Joshua Telser
- Department of Biological, Physical and Health Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory (NHMFL), Florida State University, Tallahassee, Florida 32310, United States
| | - Benjamin W Stein
- Los Alamos National Laboratory (LANL), Los Alamos, New Mexico 87545, United States
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Kumar P, SantaLucia DJ, Kaniewska-Laskowska K, Lindeman SV, Ozarowski A, Krzystek J, Ozerov M, Telser J, Berry JF, Fiedler AT. Probing the Magnetic Anisotropy of Co(II) Complexes Featuring Redox-Active Ligands. Inorg Chem 2020; 59:16178-16193. [DOI: 10.1021/acs.inorgchem.0c01812] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Praveen Kumar
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - Daniel J. SantaLucia
- Department of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Kinga Kaniewska-Laskowska
- Department of Inorganic Chemistry, Faculty of Chemistry, Gdańsk University of Technology, Gdańsk PL-80-233, Poland
| | - Sergey V. Lindeman
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - J. Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Mykhaylo Ozerov
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Joshua Telser
- Department of Biological, Chemical and Physical Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - John F. Berry
- Department of Chemistry, University of Wisconsin−Madison, Madison, Wisconsin 53706, United States
| | - Adam T. Fiedler
- Department of Chemistry, Marquette University, Milwaukee, Wisconsin 53201, United States
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Sanakis Y, Krzystek J, Maganas D, Grigoropoulos A, Ferentinos E, Kostakis MG, Petroulea V, Pissas M, Thirunavukkuarasu K, Wernsdorfer W, Neese F, Kyritsis P. Magnetic Properties and Electronic Structure of the S = 2 Complex [Mn III{(OPPh 2) 2N} 3] Showing Field-Induced Slow Magnetization Relaxation. Inorg Chem 2020; 59:13281-13294. [PMID: 32897702 DOI: 10.1021/acs.inorgchem.0c01636] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The high-spin S = 2 Mn(III) complex [Mn{(OPPh2)2N}3] (1Mn) exhibits field-induced slow relaxation of magnetization (Inorg. Chem. 2013, 52, 12869). Magnetic susceptibility and dual-mode X-band electron paramagnetic resonance (EPR) studies revealed a negative value of the zero-field-splitting (zfs) parameter D. In order to explore the magnetic and electronic properties of 1Mn in detail, a combination of experimental and computational studies is presented herein. Alternating-current magnetometry on magnetically diluted samples (1Mn/1Ga) of 1Mn in the diamagnetic gallium analogue, [Ga{(OPPh2)2N}3], indicates that the slow relaxation behavior of 1Mn is due to the intrinsic properties of the individual molecules of 1Mn. Investigation of the single-crystal magnetization of both 1Mn and 1Mn/1Ga by a micro-SQUID device reveals hysteresis loops below 1 K. Closed hysteresis loops at a zero direct-current magnetic field are observed and attributed to fast quantum tunneling of magnetization. High-frequency and -field EPR (HFEPR) spectroscopic studies reveal that, apart from the second-order zfs terms (D and E), fourth-order terms (B4m) are required in order to appropriately describe the magnetic properties of 1Mn. These studies provide accurate spin-Hamiltonian (sH) parameters of 1Mn, i.e., zfs parameters |D| = 3.917(5) cm-1, |E| = 0.018(4) cm-1, B04 = B42 = 0, and B44 = (3.6 ± 1.7) × 10-3 cm-1 and g = [1.994(5), 1.996(4), 1.985(4)], and confirm the negative sign of D. Parallel-mode X-band EPR studies on 1Mn/1Ga and CH2Cl2 solutions of 1Mn probe the electronic-nuclear hyperfine interactions in the solid state and solution. The electronic structure of 1Mn is investigated by quantum-chemical calculations by employing recently developed computational protocols that are grounded on ab initio wave function theory. From computational analysis, the contributions of spin-spin and spin-orbit coupling to the magnitude of D are obtained. The calculations provide also computed values of the fourth-order zfs terms B4m, as well as those of the g and hyperfine interaction tensor components. In all cases, a very good agreement between the computed and experimentally determined sH parameters is observed. The magnetization relaxation properties of 1Mn are rationalized on the basis of the composition of the ground-state wave functions in the absence or presence of an external magnetic field.
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Affiliation(s)
- Yiannis Sanakis
- Institute of Nanoscience and Nanotechnolgy, National Centre of Scientific Research "Demokritos", Aghia Paraskevi 15310, Attiki, Greece
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Dimitrios Maganas
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Alexios Grigoropoulos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
| | - Eleftherios Ferentinos
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
| | - Marios G Kostakis
- Analytical Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens,15771 Athens, Greece
| | - Vasiliki Petroulea
- Institute of Nanoscience and Nanotechnolgy, National Centre of Scientific Research "Demokritos", Aghia Paraskevi 15310, Attiki, Greece
| | - Michael Pissas
- Institute of Nanoscience and Nanotechnolgy, National Centre of Scientific Research "Demokritos", Aghia Paraskevi 15310, Attiki, Greece
| | | | - Wolfgang Wernsdorfer
- Physikalisches Institut, Karlsruher Institut für Technologie, Wolfgang-Gaede-Strasse 1, 76131 Karlsruhe, Germany.,Institute of Quantum Materials and Technologies, Karlsruher Institut für Technologie, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen, Germany
| | - Frank Neese
- Max-Planck-Institut für Kohlenforschung, Kaiser-Wilhelm-Platz 1, 45470 Mülheim an der Ruhr, Germany
| | - Panayotis Kyritsis
- Inorganic Chemistry Laboratory, Department of Chemistry, National and Kapodistrian University of Athens, 15771 Athens, Greece
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8
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Krzystek J, Schnegg A, Aliabadi A, Holldack K, Stoian SA, Ozarowski A, Hicks SD, Abu-Omar MM, Thomas KE, Ghosh A, Caulfield KP, Tonzetich ZJ, Telser J. Advanced Paramagnetic Resonance Studies on Manganese and Iron Corroles with a Formal d 4 Electron Count. Inorg Chem 2020; 59:1075-1090. [PMID: 31909979 DOI: 10.1021/acs.inorgchem.9b02635] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Metallocorroles wherein the metal ion is MnIII and formally FeIV are studied here using field- and frequency-domain electron paramagnetic resonance techniques. The MnIII corrole, Mn(tpfc) (tpfc = 5,10,15-tris(pentafluorophenyl)corrole trianion), exhibits the following S = 2 zero-field splitting (zfs) parameters: D = -2.67(1) cm-1, |E| = 0.023(5) cm-1. This result and those for other MnIII tetrapyrroles indicate that when D ≈ - 2.5 ± 0.5 cm-1 for 4- or 5-coordinate and D ≈ - 3.5 ± 0.5 cm-1 for 6-coordinate complexes, the ground state description is [MnIII(Cor3-)]0 or [MnIII(P2-)]+ (Cor = corrole, P = porphyrin). The situation for formally FeIV corroles is more complicated, and it has been shown that for Fe(Cor)X, when X = Ph (phenyl), the ground state is a spin triplet best described by [FeIV(Cor3-)]+, but when X = halide, the ground state corresponds to [FeIII(Cor•2-)]+, wherein an intermediate spin (S = 3/2) FeIII is antiferromagnetically coupled to a corrole radical dianion (S = 1/2) to also give an S = 1 ground state. These two valence isomers can be distinguished by their zfs parameters, as determined here for Fe(tpc)X, X = Ph, Cl (tpc = 5,10,15-triphenylcorrole trianion). The complex with axial phenyl gives D = 21.1(2) cm-1, while that with axial chloride gives D = 14.6(1) cm-1. The D value for Fe(tpc)Ph is in rough agreement with the range of values reported for other FeIV complexes. In contrast, the D value for Fe(tpc)Cl is inconsistent with an FeIV description and represents a different type of iron center. Computational studies corroborate the zfs for the two types of iron corrole complexes. Thus, the zfs of metallocorroles can be diagnostic as to the electronic structure of a formally high oxidation state metallocorrole, and by extension to metalloporphyrins, although such studies have yet to be performed.
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Affiliation(s)
- J Krzystek
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Alexander Schnegg
- EPR Research Group , Max Planck Institute for Chemical Energy Conversion , Stiftstraße 34-36 , D-45470 Mülheim Ruhr , Germany.,Berlin Joint EPR Laboratory , Helmholtz-Zentrum Berlin , Kekulestraße 5 , D-12489 Berlin , Germany
| | - Azar Aliabadi
- Berlin Joint EPR Laboratory , Helmholtz-Zentrum Berlin , Kekulestraße 5 , D-12489 Berlin , Germany
| | - Karsten Holldack
- Institut für Methoden und Instrumentierung der Forschung mit Synchrotronstrahlung am Elektronenspeicherring BESSY II , Albert-Einstein-Straße 15 , D-12489 Berlin , Germany
| | - Sebastian A Stoian
- Department of Chemistry , University of Idaho , Moscow , Idaho 83844 , United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Scott D Hicks
- Department of Chemistry , Purdue University , West Lafayette , Indiana 47907 , United States
| | - Mahdi M Abu-Omar
- Departments of Chemistry and Biochemistry , University of California , Santa Barbara , California 93106-9510 , United States
| | - Kolle E Thomas
- Department of Chemistry , UiT-The Arctic University of Norway , N-9037 Tromsø , Norway
| | - Abhik Ghosh
- Department of Chemistry , UiT-The Arctic University of Norway , N-9037 Tromsø , Norway
| | - Kenneth P Caulfield
- Department of Chemistry , University of Texas at San Antonio (UTSA) , One UTSA Circle , San Antonio , Texas 78249 , United States
| | - Zachary J Tonzetich
- Department of Chemistry , University of Texas at San Antonio (UTSA) , One UTSA Circle , San Antonio , Texas 78249 , United States
| | - Joshua Telser
- Department of Biological, Physical, and Health Sciences , Roosevelt University , Chicago , Illinois 60605 , United States
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Hickey AK, Greer SM, Valdez-Moreira JA, Lutz SA, Pink M, DeGayner JA, Harris TD, Hill S, Telser J, Smith JM. A Dimeric Hydride-Bridged Complex with Geometrically Distinct Iron Centers Giving Rise to an S = 3 Ground State. J Am Chem Soc 2019; 141:11970-11975. [PMID: 31283232 DOI: 10.1021/jacs.9b04389] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Structural and spectroscopic characterization of the dimeric iron hydride complex [Ph2B(tBuIm)2FeH]2 reveals an unusual structure in which a tetrahedral iron(II) site (S = 2) is connected to a square planar iron(II) site (S = 1) by two bridging hydride ligands. Magnetic susceptibility reveals strong ferromagnetic coupling between iron centers, with a coupling constant of J = +110(12) cm-1, to give an S = 3 ground state. High-frequency and -field electron paramagnetic resonance (HFEPR) spectroscopy confirms this model. A qualitative molecular orbital analysis of the electronic structure, as supported by electronic structure calculations, reveals that the observed spin configuration results from the orthogonal alignment of two geometrically distinct four-coordinate iron fragments held together by highly covalent hydride ligands.
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Affiliation(s)
- Anne K Hickey
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Samuel M Greer
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Juan A Valdez-Moreira
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Sean A Lutz
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Maren Pink
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405 , United States
| | - Jordan A DeGayner
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - T David Harris
- Department of Chemistry , Northwestern University , Evanston , Illinois 60208 , United States
| | - Stephen Hill
- National High Magnetic Field Laboratory , Florida State University , Tallahassee , Florida 32310 , United States
| | - Joshua Telser
- Department of Biological, Physical and Health Sciences , Roosevelt University , Chicago , Illinois 60605 , United States
| | - Jeremy M Smith
- Department of Chemistry , Indiana University , 800 East Kirkwood Avenue , Bloomington , Indiana 47405 , United States
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Lee HB, Shiau AA, Oyala PH, Marchiori DA, Gul S, Chatterjee R, Yano J, Britt RD, Agapie T. Tetranuclear [Mn IIIMn 3IVO 4] Complexes as Spectroscopic Models of the S 2 State of the Oxygen Evolving Complex in Photosystem II. J Am Chem Soc 2018; 140:17175-17187. [PMID: 30407806 DOI: 10.1021/jacs.8b09961] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Despite extensive biochemical, spectroscopic, and computational studies, the mechanism of biological water oxidation by the oxygen evolving complex (OEC) of Photosystem II remains a subject of significant debate. Mechanistic proposals are guided by the characterization of reaction intermediates such as the S2 state, which features two characteristic EPR signals at g = 2 and g = 4.1. Two nearly isoenergetic structural isomers have been proposed as the source of these distinct signals, but relevant structure-electronic structure studies remain rare. Herein, we report the synthesis, crystal structure, electrochemistry, XAS, magnetic susceptibility, variable temperature CW-EPR, and pulse EPR data for a series of [MnIIIMn3IVO4] cuboidal complexes as spectroscopic models of the S2 state of the OEC. Resembling the oxidation state and EPR spectra of the S2 state of the OEC, these model complexes show two EPR signals, a broad low field signal and a multiline signal, that are remarkably similar to the biological system. The effect of systematic changes in the nature of the bridging ligands on spectroscopy were studied. Results show that the electronic structure of tetranuclear Mn complexes is highly sensitive to even small geometric changes and the nature of the bridging ligands. Our model studies suggest that the spectroscopic properties of the OEC may also react very sensitively to small changes in structure; the effect of protonation state and other reorganization processes need to be carefully assessed.
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Affiliation(s)
- Heui Beom Lee
- Department of Chemistry and Chemical Engineering , California Institute of Technology , 1200 E California Blvd MC 127-72 , Pasadena , California 91125 , United States
| | - Angela A Shiau
- Department of Chemistry and Chemical Engineering , California Institute of Technology , 1200 E California Blvd MC 127-72 , Pasadena , California 91125 , United States
| | - Paul H Oyala
- Department of Chemistry and Chemical Engineering , California Institute of Technology , 1200 E California Blvd MC 127-72 , Pasadena , California 91125 , United States
| | - David A Marchiori
- Department of Chemistry , University of California Davis , One Shields Avenue , Davis , California 95616 , United States
| | - Sheraz Gul
- Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Ruchira Chatterjee
- Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - Junko Yano
- Molecular Biophysics and Integrated Bioimaging Division , Lawrence Berkeley National Laboratory , Berkeley , California 94720 , United States
| | - R David Britt
- Department of Chemistry , University of California Davis , One Shields Avenue , Davis , California 95616 , United States
| | - Theodor Agapie
- Department of Chemistry and Chemical Engineering , California Institute of Technology , 1200 E California Blvd MC 127-72 , Pasadena , California 91125 , United States
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11
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Tadyszak K, Rudowicz C, Ohta H, Sakurai T. Electron magnetic resonance data on high-spin Mn(III; S = 2) ions in porphyrinic and salen complexes modeled by microscopic spin Hamiltonian approach. J Inorg Biochem 2017; 175:36-46. [DOI: 10.1016/j.jinorgbio.2017.06.006] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2017] [Revised: 06/15/2017] [Accepted: 06/19/2017] [Indexed: 10/19/2022]
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Schweinfurth D, Krzystek J, Atanasov M, Klein J, Hohloch S, Telser J, Demeshko S, Meyer F, Neese F, Sarkar B. Tuning Magnetic Anisotropy Through Ligand Substitution in Five-Coordinate Co(II) Complexes. Inorg Chem 2017; 56:5253-5265. [DOI: 10.1021/acs.inorgchem.7b00371] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- David Schweinfurth
- Institut für
Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße
34-36, D-14195 Berlin, Germany
| | - J. Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Mihail Atanasov
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
- Institute of General and Inorganic Chemistry, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria
| | - Johannes Klein
- Institut für
Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße
34-36, D-14195 Berlin, Germany
| | - Stephan Hohloch
- Institut für
Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße
34-36, D-14195 Berlin, Germany
| | - Joshua Telser
- Department of Biological, Chemical, and Physical Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Serhiy Demeshko
- Universität Göttingen, Institut
für Anorganische Chemie, Tammanstraße 4, D-37077 Göttingen, Germany
| | - Franc Meyer
- Universität Göttingen, Institut
für Anorganische Chemie, Tammanstraße 4, D-37077 Göttingen, Germany
| | - Frank Neese
- Max Planck Institute for Chemical Energy Conversion, Stiftstraße 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Biprajit Sarkar
- Institut für
Chemie und Biochemie, Freie Universität Berlin, Fabeckstraße
34-36, D-14195 Berlin, Germany
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13
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Bucinsky L, Rohde GT, Que L, Ozarowski A, Krzystek J, Breza M, Telser J. HFEPR and Computational Studies on the Electronic Structure of a High-Spin Oxidoiron(IV) Complex in Solution. Inorg Chem 2016; 55:3933-45. [PMID: 27031000 DOI: 10.1021/acs.inorgchem.6b00169] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nonheme iron enzymes perform diverse and important functions in biochemistry. The active form of these enzymes comprises the ferryl, oxidoiron(IV), [FeO](2+) unit. In enzymes, this unit is in the high-spin, quintet, S = 2, ground state, while many synthetic model compounds exist in the spin triplet, S = 1, ground state. Recently, however, Que and co-workers reported an oxidoiron(IV) complex with a quintet ground state, [FeO(TMG3tren)](OTf)2, where TMG3tren = 1,1,1-tris{2-[N2-(1,1,3,3-tetramethylguanidino)]ethyl}amine and OTf = CF3SO3(-). The trigonal geometry imposed by this ligand, as opposed to the tetragonal geometry of earlier model complexes, favors the high-spin ground state. Although [FeO(TMG3tren)](2+) has been earlier probed by magnetic circular dichroism (MCD) and Mössbauer spectroscopies, the technique of high-frequency and -field electron paramagnetic resonance (HFEPR) is superior for describing the electronic structure of the iron(IV) center because of its ability to establish directly the spin-Hamiltonian parameters of high-spin metal centers with high precision. Herein we describe HFEPR studies on [FeO(TMG3tren)](OTf)2 generated in situ and confirm the S = 2 ground state with the following parameters: D = +4.940(5) cm(-1), E = 0.000(5), B4(0) = -14(1) × 10(-4) cm(-1), g⊥ = 2.006(2), and g∥ = 2.03(2). Extraction of a fourth-order spin-Hamiltonian parameter is unusual for HFEPR and impossible by other techniques. These experimental results are combined with state-of-the-art computational studies along with previous structural and spectroscopic results to provide a complete picture of the electronic structure of this biomimetic complex. Specifically, the calculations reproduce well the spin-Hamiltonian parameters of the complex, provide a satisfying geometrical picture of the S = 2 oxidoiron(IV) moiety, and demonstrate that the TMG3tren is an "innocent" ligand.
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Affiliation(s)
- Lukas Bucinsky
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology , Radlinského 9, SK-81237 Bratislava, Slovakia
| | - Gregory T Rohde
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Lawrence Que
- Department of Chemistry and Center for Metals in Biocatalysis, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University , Tallahassee, Florida 32310, United States
| | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University , Tallahassee, Florida 32310, United States
| | - Martin Breza
- Institute of Physical Chemistry and Chemical Physics, Faculty of Chemical and Food Technology, Slovak University of Technology , Radlinského 9, SK-81237 Bratislava, Slovakia
| | - Joshua Telser
- Department of Biological, Chemical and Physical Sciences, Roosevelt University , Chicago, Illinois 60605, United States
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Açıkgöz M, Gnutek P, Rudowicz C. Magnetostructural relationships for Ni(II) ions at octahedral sites in [Ni Zn1−(C2O4)(dmiz)2]: Computational study of zero-field splitting and using superposition model. Polyhedron 2015. [DOI: 10.1016/j.poly.2015.08.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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15
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Wijeratne GB, Zolnhofer EM, Fortier S, Grant LN, Carroll PJ, Chen CH, Meyer K, Krzystek J, Ozarowski A, Jackson TA, Mindiola DJ, Telser J. Electronic Structure and Reactivity of a Well-Defined Mononuclear Complex of Ti(II). Inorg Chem 2015; 54:10380-97. [DOI: 10.1021/acs.inorgchem.5b01796] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Gayan B. Wijeratne
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Eva M. Zolnhofer
- Inorganic Chemistry, Department of Chemistry
and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - Skye Fortier
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Lauren N. Grant
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Patrick J. Carroll
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Chun-Hsing Chen
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
| | - Karsten Meyer
- Inorganic Chemistry, Department of Chemistry
and Pharmacy, Friedrich-Alexander University Erlangen-Nürnberg, 91058 Erlangen, Germany
| | - J. Krzystek
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Andrew Ozarowski
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Timothy A. Jackson
- Department of Chemistry, University of Kansas, Lawrence, Kansas 66045, United States
| | - Daniel J. Mindiola
- Department of Chemistry and Molecular Structure Center, Indiana University, Bloomington, Indiana 47405, United States
- Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, United States
| | - Joshua Telser
- Department of
Biological, Chemical and Physical Sciences, Roosevelt University, Chicago, Illinois 60605, United States
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16
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Jiang SD, Maganas D, Levesanos N, Ferentinos E, Haas S, Thirunavukkuarasu K, Krzystek J, Dressel M, Bogani L, Neese F, Kyritsis P. Direct Observation of Very Large Zero-Field Splitting in a Tetrahedral Ni(II)Se4 Coordination Complex. J Am Chem Soc 2015; 137:12923-8. [PMID: 26352187 DOI: 10.1021/jacs.5b06716] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The high-spin (S = 1) tetrahedral Ni(II) complex [Ni{(i)Pr2P(Se)NP(Se)(i)Pr2}2] was investigated by magnetometry, spectroscopic, and quantum chemical methods. Angle-resolved magnetometry studies revealed the orientation of the magnetization principal axes. The very large zero-field splitting (zfs), D = 45.40(2) cm(-1), E = 1.91(2) cm(-1), of the complex was accurately determined by far-infrared magnetic spectroscopy, directly observing transitions between the spin sublevels of the triplet ground state. These are the largest zfs values ever determined--directly--for a high-spin Ni(II) complex. Ab initio calculations further probed the electronic structure of the system, elucidating the factors controlling the sign and magnitude of D. The latter is dominated by spin-orbit coupling contributions of the Ni ions, whereas the corresponding effects of the Se atoms are remarkably smaller.
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Affiliation(s)
- Shang-Da Jiang
- 1. Physikalisches Institut, Universität Stuttgart , Pfaffenwaldring 57, D-70550, Stuttgart, Germany
| | - Dimitrios Maganas
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Nikolaos Levesanos
- Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, Athens, 157 71 Greece
| | - Eleftherios Ferentinos
- Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, Athens, 157 71 Greece
| | - Sabrina Haas
- 1. Physikalisches Institut, Universität Stuttgart , Pfaffenwaldring 57, D-70550, Stuttgart, Germany
| | | | - J Krzystek
- National High Magnetic Field Laboratory, Florida State University , Tallahassee, Florida 32310, United States
| | - Martin Dressel
- 1. Physikalisches Institut, Universität Stuttgart , Pfaffenwaldring 57, D-70550, Stuttgart, Germany
| | - Lapo Bogani
- 1. Physikalisches Institut, Universität Stuttgart , Pfaffenwaldring 57, D-70550, Stuttgart, Germany
| | - Frank Neese
- Max-Planck-Institut für Chemische Energiekonversion , Stiftstrasse 34-36, D-45470 Mülheim an der Ruhr, Germany
| | - Panayotis Kyritsis
- Laboratory of Inorganic Chemistry, Department of Chemistry, National and Kapodistrian University of Athens , Panepistimiopolis, Athens, 157 71 Greece
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17
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Krzystek J, Telser J, Li J, Subramanian MA. Magnetic Properties and Electronic Structure of Manganese-Based Blue Pigments: A High-Frequency and -Field EPR Study. Inorg Chem 2015; 54:9040-5. [DOI: 10.1021/acs.inorgchem.5b01306] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Affiliation(s)
- J. Krzystek
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
| | - Joshua Telser
- Department
of Biological, Chemical, and Physical Sciences, Roosevelt University, Chicago, Illinois 60605, United States
| | - Jun Li
- Department
of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
| | - M. A. Subramanian
- Department
of Chemistry, Oregon State University, Corvallis, Oregon 97331, United States
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18
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Synthesis, structure and magnetism of manganese and iron dipicolinates with N,N′-donor ligands. Inorganica Chim Acta 2015. [DOI: 10.1016/j.ica.2014.10.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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High-frequency and high-field electron paramagnetic resonance (HFEPR): a new spectroscopic tool for bioinorganic chemistry. J Biol Inorg Chem 2014; 19:297-318. [DOI: 10.1007/s00775-013-1084-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 12/27/2013] [Indexed: 12/27/2022]
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20
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Reger DL, Pascui AE, Foley EA, Smith MD, Jezierska J, Ozarowski A. Dinuclear Metallacycles with Single M–O(H)–M Bridges [M = Fe(II), Co(II), Ni(II), Cu(II)]: Effects of Large Bridging Angles on Structure and Antiferromagnetic Superexchange Interactions. Inorg Chem 2014; 53:1975-88. [DOI: 10.1021/ic4017905] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Daniel L. Reger
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Andrea E. Pascui
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Elizabeth A. Foley
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Mark D. Smith
- Department
of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Julia Jezierska
- Faculty
of Chemistry, University of Wrocław, 50-383 Wrocław, Poland
| | - Andrew Ozarowski
- National
High Magnetic Field Laboratory, Florida State University, Tallahassee, Florida 32310, United States
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21
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Schweinfurth D, Klein J, Hohloch S, Dechert S, Demeshko S, Meyer F, Sarkar B. Influencing the coordination mode of tbta (tbta = tris[(1-benzyl-1H-1,2,3-triazol-4-yl)methyl]amine) in dicobalt complexes through changes in metal oxidation states. Dalton Trans 2013; 42:6944-52. [DOI: 10.1039/c3dt00102d] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
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