1
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Peprah F, Tarantola GE, Plaman AS, Vu EL, Huynh AB, Durr CB. Synthesis and catalytic activity of single-site group V alkoxide complexes for the ring-opening polymerization of ε-caprolactone. Dalton Trans 2024; 53:7073-7080. [PMID: 38567482 DOI: 10.1039/d4dt00422a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
The synthesis, characterization, and ring-opening polymerization (ROP) activity of a family of niobium and tantalum alkoxide catalysts was studied. The final catalysts are made in a two-step synthesis, first by reacting the desired homoleptic metal ethoxide with a phenolketoimine ligand to form a series of synthetic intermediates, followed by reaction with catechol to produce a catalytic platform with a single ethoxide initiator. By using two separate ligands, the electronic properties of the catalyst can be tuned, and the molecular weight of the polymer can be increased. It was found that synthetic intermediates adopted a mer geometry both in solution and in the solid state. This mer geometry was retained for the final catechol derivatives, however in one case, where catechol was substituted for 3-methoxycatechol, the molecule adopted a highly distorted fac geometry. Catalytic ROP activity of the synthetic intermediates and final catechol derivatives with ε-caprolactone was studied through a kinetic analysis. In all seven cases studied the reactions proceeded through the expected coordination-insertion mechanism, following pseudo first-order kinetics and increasing in Mn linearly vs. conversion. The single-initiator catechol derivatives increased the Mn by three times compared to that of the three-initiator synthetic intermediates with little decrease in the overall reaction rate. Both the nature of the ligand and metal were found to impact the rate of reaction in these systems. By switching from an electron donating ligand to an electron withdrawing ligand, the rate was found to nearly double. Tantalum species were faster than their niobium counterparts by ∼3 times in the synthetic intermediates and ∼1.5 times in the catechol derivatives. This observed periodicity supports recent literature findings in this area.
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Affiliation(s)
- Frank Peprah
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Grace E Tarantola
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Alyson S Plaman
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Emily L Vu
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Alyssa B Huynh
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
| | - Christopher B Durr
- Department of Chemistry, Amherst College, 25 East Drive, Amherst, Massachusetts 01002, USA.
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2
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Buchard A, Davidson MG, Gobius du Sart G, Jones MD, Kociok-Köhn G, McCormick SN, McKeown P. Unexpected Periodicity in Cationic Group 5 Initiators for the Ring-Opening Polymerization of Lactones. Inorg Chem 2024; 63:27-38. [PMID: 38118120 PMCID: PMC10777398 DOI: 10.1021/acs.inorgchem.3c03854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Revised: 11/23/2023] [Accepted: 12/04/2023] [Indexed: 12/22/2023]
Abstract
ε-Caprolactone (ε-CL) adducts of cationic, amine tris(phenolate)-supported niobium(V) and tantalum(V) ethoxides initiate the ring-opening polymerization of lactones. The Ta(V) species prepared and applied catalytically herein exhibits higher activity in the ring-opening polymerization (ROP) of ε-caprolactone than the previously reported, isostructural Nb(V) complex, contradicting literature comparisons of Nb(V)- and Ta(V)-based protocols. Both systems also initiate the ROP of δ-valerolactone and rac-β-butyrolactone, kinetic studies confirming retention of higher activity by the Ta congener. Polymerizations of rac-β-butyrolactone and δ-valerolactone were previously unrealized under Group V- or Ta-mediated conditions, respectively, although the former has afforded only low molecular weight, cyclic poly-3-hydroxybutyrate. Cationic ethoxo-Nb(V) and -Ta(V) δ-valerolactone adducts are also reported, demonstrating the facility of δ-valerolactone as a ligand and the generality of the synthetic method. Both δ-valerolactone-bearing complexes initiate the ROP of ε-caprolactone, δ-valerolactone, and rac-β-butyrolactone. Accordingly, we have elucidated trends in reactivity and investigated the initiation mechanism for such systems, the insertion event being predicated upon intramolecular nucleophilic attack on the coordinated lactone by the adjacent alkoxide moiety. This mechanism enables quantitative, stoichiometric installation of a single monomer residue distinct from the bulk of the polymer chain, and permits modification of polymer properties via both manipulation of the molecular architecture and tuning of the polymerization kinetics, and thus dispersity, through hitherto inaccessible independent control of the initiation event.
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Affiliation(s)
- Antoine Buchard
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Matthew G. Davidson
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | | | - Matthew D. Jones
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Gabriele Kociok-Köhn
- Material
and Chemical Characterization and Analysis Facility (MC), University of Bath, Bath BA2 7AY, United Kingdom
| | - Strachan N. McCormick
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, United Kingdom
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
| | - Paul McKeown
- Department
of Chemistry, University of Bath, Bath BA2 7AY, United Kingdom
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3
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Buchard A, Davidson MG, Gobius du Sart G, Jones MD, Kociok-Köhn G, McCormick SN, Mckeown P. Coordination of ε-Caprolactone to a Cationic Niobium(V) Alkoxide Complex: Fundamental Insight into Ring-Opening Polymerization via Coordination-Insertion. Inorg Chem 2023; 62:15688-15699. [PMID: 37695575 PMCID: PMC10523432 DOI: 10.1021/acs.inorgchem.3c02491] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Indexed: 09/12/2023]
Abstract
We report three niobium-based initiators for the catalytic ring-opening polymerization (ROP) of ε-caprolactone, exhibiting good activity and molecular weight control. In particular, we have prepared on the gram-scale and fully characterized a monometallic cationic alkoxo-Nb(V) ε-caprolactone adduct representing, to the best of our knowledge, an unprecedented example of a metal complex with an intact lactone monomer and a functional ROP-initiating group simultaneously coordinated at the metal center. At 80 °C, all three systems initiate the immortal solution-state ROP of ε-caprolactone via a coordination-insertion mechanism, which has been confirmed through experimental studies, and is supported by computational data. Natural bond orbital calculations further indicate that polymerization may necessitate isomerization about the metal center between the alkoxide chain and the coordinated monomer. The observations made in this work are expected to inform mechanistic understanding both of amine tris(phenolate)-supported metal alkoxide ROP initiators, including various highly stereoselective systems for the polymerization of lactides and of coordination-insertion-type ROP protocols more broadly.
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Affiliation(s)
- Antoine Buchard
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | - Matthew G. Davidson
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | | | - Matthew D. Jones
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | - Gabriele Kociok-Köhn
- Material
and Chemical Characterization and Analysis Facility (MC2), University of Bath, Bath BA2 7AY, U.K.
| | - Strachan N. McCormick
- Institute
for Sustainability, University of Bath, Bath BA2 7AY, U.K.
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
| | - Paul Mckeown
- Department
of Chemistry, University of Bath, Bath BA2 7AY, U.K.
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Plaman A, Durr CB. Investigating the Ring-Opening Polymerization Activity of Niobium and Tantalum Ethoxides Supported by Phenoxyimine Ligands. ACS OMEGA 2022; 7:23995-24003. [PMID: 35847339 PMCID: PMC9281319 DOI: 10.1021/acsomega.2c02880] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
A variety of metal catalysts from around the periodic table have been studied for the ring-opening polymerization (ROP) of cyclic esters. Within this field, group V catalysts have been rarely explored. To better understand the effect the choice of metal and ligand has on ROP activity, a series of 10 niobium and tantalum alkoxide catalysts, supported by a range of phenoxyimine ligands, were synthesized. The electronics and steric bulk of the ligands were varied on the phenoxy group ( t Bu, Cl, and OMe) and the imine group (Ph; 2,6-diMePh; 2,6-di i PrPh; and 2,4,6-tri t BuPh) to probe their effect on the catalyst structure and activity. Catalysts were characterized with 1D, 2D, and variable-temperature NMR techniques to determine their structure in solution. Single crystal X-ray diffraction studies were conducted to establish their solid-state structure. The 10 catalysts are pseudo-octahedral, and each shows ligand coordination through phenoxy-oxygen and imine-nitrogen (O,N). In the case of the o-vanillin ligand set, however, evidence was found for O,O-coordination of the ligand when the steric encumbrance of the imine-nitrogen was increased. Each catalyst was active for the ring-opening polymerization of both rac-lactide (LA) and ε-caprolactone (CL) in the absence of solvent at 140 °C. In the case of CL, the catalysts supported by chloro-containing ligands showed the most polymerization control based on final polymer molecular weight and dispersity. Ligand trends were less clear for the polymerization of LA, though in all cases the catalysts were more controlled than the parent homoleptic alkoxide [M(OEt)5; M = Nb or Ta]. The most promising catalyst in the family was tested for copolymerization activity of LA and CL in one pot. Copolymerization of the two monomers was successful and yielded random poly(caprolactone-co-lactide).
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Zhang X, Prior TJ, Redshaw C. Niobium and Tantalum complexes derived from the acids Ph 2C(X)CO 2H (X = OH, NH 2): synthesis, structure and ROP capability. NEW J CHEM 2022. [DOI: 10.1039/d2nj02527b] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Tetranuclear [M4(OEt)8(L1)4(μ-O)2] and dinuclear [M2(OEt)4(L2H2)4(μ-O)] complexes (M = Nb, Ta) derived from benzilic acid (L1H2) and diphenylglycine (L2H3) have been structurally characterized and are capable of the ROP of μ-caprolactone and rac-lactide.
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Affiliation(s)
- Xin Zhang
- Plastics Collaboratory, Department of Chemistry, The University of Hull, Cottingham Rd, Hull HU6 7RX, UK
| | - Timothy J. Prior
- Plastics Collaboratory, Department of Chemistry, The University of Hull, Cottingham Rd, Hull HU6 7RX, UK
| | - Carl Redshaw
- Plastics Collaboratory, Department of Chemistry, The University of Hull, Cottingham Rd, Hull HU6 7RX, UK
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6
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Neto ADBS, Alves da Cruz MG, Jeanneau E, Oliveira AC, Essayem N, Mishra S. Designed sol–gel precursors for atomically dispersed Nb and Pb within TiO2 as catalysts for dihydroxyacetone transformation. Dalton Trans 2021; 50:1604-1609. [DOI: 10.1039/d0dt03726e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
New N-methyldiethanolamine-modified metal alkoxides were synthesized and employed as sol–gel precursors to obtain atomically dispersed catalysts with high surface area and tunable acid–base properties.
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Affiliation(s)
- Antonio de Brito Santiago Neto
- Université Claude Bernard Lyon 1
- CNRS
- UMR 5256
- Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON)
- 69626 Villeurbanne
| | - Márcia Gabriely Alves da Cruz
- Université Claude Bernard Lyon 1
- CNRS
- UMR 5256
- Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON)
- 69626 Villeurbanne
| | - Erwann Jeanneau
- Université Claude Bernard Lyon 1
- Centre de Diffractométrie Henri Longchambon
- 69100 Villeurbanne
- France
| | - Alcineia Conceição Oliveira
- Universidade Federal do Ceará
- Campus do Pici-Bloco 940
- Departamento de Química Analítica e Fisioquímica
- 60.000.000 Fortaleza
- Brazil
| | - Nadine Essayem
- Université Claude Bernard Lyon 1
- CNRS
- UMR 5256
- Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON)
- 69626 Villeurbanne
| | - Shashank Mishra
- Université Claude Bernard Lyon 1
- CNRS
- UMR 5256
- Institut de Recherches sur la Catalyse et l'Environnement de Lyon (IRCELYON)
- 69626 Villeurbanne
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7
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Ji J, Chen C, Jia AQ, Shi HT, Zhang QF. Syntheses, structures and photocatalytic properties of ruthenium complexes bearing L-methionine ligands. J Organomet Chem 2020. [DOI: 10.1016/j.jorganchem.2019.121078] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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8
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Canaj AB, Kakaroni FΕ, Collet A, Milios CJ. α-Amino acids: Natural and artificial building blocks for discrete polymetallic clusters. Polyhedron 2018. [DOI: 10.1016/j.poly.2018.05.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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9
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Pappuru S, Chakraborty D, Ramkumar V. Nb and Ta benzotriazole or benzoxazole phenoxide complexes as catalysts for the ring-opening polymerization of glycidol to synthesize hyperbranched polyglycerols. Dalton Trans 2017; 46:16640-16654. [PMID: 29168518 DOI: 10.1039/c7dt02839c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of novel mononuclear (1a-7a and 1b-6b) as well as tetranuclear (8a and 9a) niobium (Nb) and tantalum (Ta) complexes of benzotriazole or benzoxazole phenoxide pro-ligands bearing different substituents at the ortho and para positions of the phenol rings were synthesized and characterized. The reaction of NbCl5 or TaCl5 with one equivalent of benzotriazole or benzoxazole phenoxide pro-ligands (L1H-L6H) in dry toluene or chloroform produced the corresponding chloride (1a-6a and 1b-6b) and ethoxy (7a) mononuclear Nb and Ta complexes in high yields. Furthermore, from the mononuclear Nb complexes (1a or 4a), a new structural form of tetrameric niobium complexes (8a and 9a) was synthesized through a controlled hydrolysis reaction. The molecular structures of complexes 1b, 4b, 7a, 8a and 9a were unambiguously confirmed by single crystal X-ray diffraction analyses. Furthermore, all these complexes (1a-9a and 1b-6b) were tested as catalysts for the ring-opening polymerisation (ROP) of glycidol to synthesize hyperbranched polyglycerols (HPG) by using 1,1,1-tris(hydroxymethyl)propane (TMP) as an initiator. The degree of branching (DB) observed was 0.30-0.54, which is an indication of hyperbranched structures. In particular, for the niobium complex with electron-withdrawing substituents on the benzoxazole phenoxide pro-ligand (5a), we achieved superior behavior for the ROP of glycidol in terms of activity, control of molecular weight (Mn) and molecular weight distributions (MWDs) (92% of glycidol to HPG, Mn = 10.52 kg mol-1, MWDs <1.33, DB = 0.53 and Tg = -57 °C). A highly hydrophilic nature was observed for the synthesized HPG polymer by water contact angle measurement (20° to 35°).
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Affiliation(s)
- Sreenath Pappuru
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Debashis Chakraborty
- Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India.
| | - Venkatachalam Ramkumar
- Single Crystal XRD Lab, Department of Chemistry, Indian Institute of Technology Madras, Chennai 600 036, Tamil Nadu, India
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10
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Duan YL, He JX, Wang W, Zhou JJ, Huang Y, Yang Y. Synthesis and characterization of dinuclear rare-earth complexes supported by amine-bridged bis(phenolate) ligands and their catalytic activity for the ring-opening polymerization of l-lactide. Dalton Trans 2016; 45:10807-20. [PMID: 27294827 DOI: 10.1039/c6dt01486k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions of amine-bridged bis(phenolate) protio-ligands N,N-bis(3,5-di-tert-butyl-2-hydroxybenzyl)aminoacetic acid (L(1)-H3) and N,N-bis[3,5-bis(α,α'-dimethylbenzyl)-2-hydroxybenzyl]aminoacetic acid (L(2)-H3), with 1 equiv. M[N(SiMe3)2]3 (M = La, Nd, Sm, Gd, Y) in THF at room temperature yielded the neutral rare-earth complexes [M2(L)2(THF)4] (L = L(1), M = La (), Nd (), Sm (), Gd (), Y (); L = L(2), M = La (), Nd (), Sm (), Gd (), Y ()). All of these complexes were characterized by single-crystal X-ray diffraction, elemental analysis and in the case of yttrium and lanthanum complexes, (1)H NMR spectroscopy. The molecular structure of revealed dinuclear species in which the eight-coordinate lanthanum centers were bonded to two oxygen atoms of two THF molecules, to three oxygen atoms and one nitrogen atom of one L(1) ligand, and two oxygen atoms of the carboxyl group of another. Complexes were also dinuclear species containing seven-coordinate metal centers similar to , albeit with bonding to one rather than two carboxyl group oxygens of another ligand. Further treatment of with excess benzyl alcohol provided dinuclear complex [La2(L(1))2(BnOH)6] (), in which each lanthanum ion is eight-coordinate, bonded to three oxygen atoms and one nitrogen atom of one ligand, three oxygen atoms of three BnOH molecules, as well as one oxygen atom of bridging carboxyl group of the other ligand. In the presence of BnOH, complexes efficiently catalyzed the ring-opening polymerization of l-lactide in a controlled manner and gave polymers with relatively narrow molecular weight distributions. The kinetic and mechanistic studies associated with the ROP of l-lactide using /BnOH initiating system have been performed.
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Affiliation(s)
- Yu-Lai Duan
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Jia-Xuan He
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Wei Wang
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Jing-Jing Zhou
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Yong Huang
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
| | - Ying Yang
- Key Laboratory of Nonferrous Metals Chemistry and Resources Utilization of Gansu Province, College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou 730000, Gansu, P. R. China.
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11
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Mandal D, Chakraborty D, Ramkumar V, Chand DK. Group 4 alkoxide complexes containing [NNO]-type scaffold: synthesis, structural characterization and polymerization studies. RSC Adv 2016. [DOI: 10.1039/c5ra26721h] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A series of new dinuclear group 4 complexes containing [NNO]-type ligands are utilized as catalysts for polymerization reactions.
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Affiliation(s)
- Dipa Mandal
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600 036
- India
| | - Debashis Chakraborty
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600 036
- India
| | | | - Dillip Kumar Chand
- Department of Chemistry
- Indian Institute of Technology Madras
- Chennai 600 036
- India
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12
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Bortoluzzi M, Bresciani G, Marchetti F, Pampaloni G, Zacchini S. MoCl5 as an effective chlorinating agent towards α-amino acids: synthesis of α-ammonium-acylchloride salts and α-amino-acylchloride complexes. Dalton Trans 2015; 44:10030-7. [PMID: 25948387 DOI: 10.1039/c5dt01002k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The reactivity of MoCl5 with α-amino acids was investigated for the first time by choosing CH2Cl2 as the reaction medium. The interaction of MoCl5 with l-proline proceeded with Cl/O interchange and led to the formation of [NH2(CH2)3CHC(O)Cl][MoOCl4], 1, in 63% yield. The reactions of MoCl5 with l-phenylalanine, sarcosine, N,N-dimethylglycine and N,N-dimethyl-l-phenylalanine afforded the α-amino-acylchloride complexes MoOCl3[O[double bond, length as m-dash]C(Cl)CH(R)N(R')(R'')] (R = CH2Ph, R' = R'' = H, 2a; R = R' = H, R'' = Me, 2b; R = H, R' = R'' = Me, 2c R = CH2Ph, R' = R'' = Me, 2d), in ca. 70% yields. According to DFT studies, 2a,d are mononuclear Mo(v) octahedral complexes bearing a N,O-coordinated α-amino-acylchloride ligand. The presumed species formed during the first stages of the MoCl5/l-phenylalanine interaction were DFT-elucidated, thus the calculated Gibbs free energy profile for the multi-step reaction of MoCl5 with l-phenylalanine was traced. [NH3CH(CH2Ph)C(O)Cl][MoOCl4], 3, acting as an intermediate in the course of the formation of 2a, was isolated by combination of [NH3CH(CH2Ph)C(O)Cl][Cl] with MoOCl3.
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Affiliation(s)
- Marco Bortoluzzi
- Ca' Foscari University of Venezia, Dipartimento di Scienze Molecolari e Nanosistemi, Dorsoduro 2137, I-30123 Venezia, Italy
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13
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Bortoluzzi M, Hayatifar M, Marchetti F, Pampaloni G, Zacchini S. Synthesis of α-amino acidato derivatives of niobium and tantalum pentahalides and their conversion into iminium salts. Inorg Chem 2015; 54:4047-55. [PMID: 25844933 DOI: 10.1021/acs.inorgchem.5b00286] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Dinuclear complexes of formula Nb2Cl9[O2CCH(R)NR'R″2-κO,κO] (R = CH2CHMe2, R' = R″ = H, 1a; R = CH2Ph, R' = R″ = H, 1b; R = CH2CH2SCH3, R' = R″ = H, 1c; R = R' = H, R″ = Me, 1d; R = CH2Ph, R' = R″ = Me, 1e; Nb2Cl9[O2C⌈CH(CH2)3NH⌉], 1f) were prepared by allowing NbCl5 to react in dichloromethane with the appropriate α-amino acid in 1:2 amino acid/Nb molar ratio. The 1:1 reactions between MX5 (M = Nb, Ta; X = Cl, Br) and a series of α-amino acids resulted in the formation of the iminium salts [(R)CH═NR'R″2][MX6] (R = CH2Ph, R' = R″ = Me: M = Nb, X = Cl, 2a; M = Nb, X = Br, 2b; M = Ta, X = Cl, 2c; M = Ta, X = Br, 2d; R = CH2Ph, R' = R″ = H, M = Nb: X = Cl, 3a; X = Br, 3b; R = CH2CHMe2, R' = R″ = H, M = Nb, X = Cl, 4; R = R' = H, R″ = Me, M = Nb, X = Cl, 5). The formate/amino acidate derivative NbCl3(O2CH)[O2CCH(CH2Ph)NMe2], 6, was isolated and identified as coproduct of the 1:1 reaction between NbCl5 and N,N-dimethyl-l-phenylalanine, leading to 2a. All of the compounds were characterized by analytical and spectroscopic methods and by X-ray diffractometry in the cases of 2a, 2b, and 2d. Moreover, density functional theory studies were carried out to shed light on mechanistic and structural aspects.
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Affiliation(s)
- Marco Bortoluzzi
- †Dipartimento di Scienze Molecolari e Nanosistemi, Ca' Foscari Università di Venezia, Dorsoduro 2137, 30123 Venezia, Italy
| | - Mohammad Hayatifar
- §Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
| | - Fabio Marchetti
- ‡Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 3, I-56124 Pisa, Italy
| | - Guido Pampaloni
- ‡Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via G. Moruzzi 3, I-56124 Pisa, Italy
| | - Stefano Zacchini
- §Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy
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14
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Bortoluzzi M, Marchetti F, Pampaloni G, Zacchini S. A crystallographically characterized salt of self-generated N-protonated tetraethylurea. Chem Commun (Camb) 2015; 51:1323-5. [DOI: 10.1039/c4cc08801h] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first crystallographically characterizedN-protonated urea (1,1,3,3-tetraethylurea, teu) was obtained by a WCl6-directed electron transfer/C–H activation process.
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Affiliation(s)
- Marco Bortoluzzi
- Ca' Foscari University of Venice
- Dipartimento di Scienze Molecolari e Nanosistemi
- I-30123 Venezia
- Italy
| | - Fabio Marchetti
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Guido Pampaloni
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Stefano Zacchini
- University of Bologna
- Dipartimento di Chimica Industriale “Toso Montanari”
- I-40136 Bologna
- Italy
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15
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Hoffmann RC, Kaloumenos M, Spiehl D, Erdem E, Repp S, Weber S, Schneider JJ. A microwave molecular solution based approach towards high-κ-tantalum(v)oxide nanoparticles: synthesis, dielectric properties and electron paramagnetic resonance spectroscopic studies of their defect chemistry. Phys Chem Chem Phys 2015; 17:31801-9. [DOI: 10.1039/c5cp05166e] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transparent and dense dielectric Ta2O5 thin films are accessible via a solution based molecular approach.
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Affiliation(s)
- R. C. Hoffmann
- Fachbereich Chemie
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie
- Technische Universität Darmstadt
- 64287 Darmstadt
- Germany
| | - M. Kaloumenos
- Integrated Electronic Systems Lab
- Technische Universität Darmstadt
- 64283 Darmstadt
- Germany
| | - D. Spiehl
- Department of Printing Technology
- Technische Universität Darmstadt
- 64283 Darmstadt
- Germany
| | - E. Erdem
- Albert-Ludwigs Ludwigs-Universität Freiburg
- Institut für Physikalische Chemie
- 79104 Freiburg
- Germany
| | - S. Repp
- Albert-Ludwigs Ludwigs-Universität Freiburg
- Institut für Physikalische Chemie
- 79104 Freiburg
- Germany
| | - S. Weber
- Albert-Ludwigs Ludwigs-Universität Freiburg
- Institut für Physikalische Chemie
- 79104 Freiburg
- Germany
| | - J. J. Schneider
- Fachbereich Chemie
- Eduard-Zintl-Institut für Anorganische und Physikalische Chemie
- Technische Universität Darmstadt
- 64287 Darmstadt
- Germany
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16
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Biancalana L, Bortoluzzi M, Forte C, Marchetti F, Pampaloni G. Structural characterization of α-amino acid complexes of molybdates: a spectroscopic and DFT study. RSC Adv 2015. [DOI: 10.1039/c4ra14236e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A joint spectroscopic and computational study has allowed us to determine the dinuclear structural core of the products of the reactions between molybdates and α-amino acids in aqueous medium.
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Affiliation(s)
- Lorenzo Biancalana
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Marco Bortoluzzi
- Ca'Foscari University of Venice
- Dipartimento di Scienze Molecolari e Nanosistemi
- I-30123 Venezia
- Italy
| | - Claudia Forte
- Istituto di Chimica dei Composti OrganoMetallici
- CNR
- Area della Ricerca di Pisa
- I-56124 Pisa
- Italy
| | - Fabio Marchetti
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Guido Pampaloni
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
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17
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Ramos AP, dos Reis DCO, Pereira RR, Dias LG, Gonçalves RR. Synthesis and spectroscopic properties of luminescent tantalum(v)-β-diketonate complexes and their use as optical sensors and the preparation of nanostructured Ta2O5. Dalton Trans 2015; 44:3829-36. [DOI: 10.1039/c4dt03548h] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
This work proposes a simple and inexpensive method to prepare a new series of β-diketonate-tantalum complexes.
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Affiliation(s)
- Ana P. Ramos
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto – Universidade de São Paulo
- Brazil
| | - Dayane C. O. dos Reis
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto – Universidade de São Paulo
- Brazil
| | - Rafael R. Pereira
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto – Universidade de São Paulo
- Brazil
| | - Luis G. Dias
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto – Universidade de São Paulo
- Brazil
| | - Rogéria R. Gonçalves
- Departamento de Química – Faculdade de Filosofia
- Ciências e Letras de Ribeirão Preto – Universidade de São Paulo
- Brazil
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18
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Bortoluzzi M, Marchetti F, Murrali MG, Pampaloni G, Zacchini S. The chlorinating behaviour of WCl6 towards α-aminoacids. Dalton Trans 2015; 44:8729-38. [DOI: 10.1039/c5dt00518c] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
WCl6 behaves as a selective chlorinating agent towards the carboxylic function of primary and secondary α-aminoacids. The initial formation of α-ammonium acylchloride salts may be followed by HCl elimination and, in the case of l-proline derived species, a clean cyclization reaction.
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Affiliation(s)
- Marco Bortoluzzi
- University of Venezia Ca’ Foscari
- Dipartimento di Scienze Molecolari e Nanosistemi
- I-30123 Venezia
- Italy
| | - Fabio Marchetti
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Maria Grazia Murrali
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Guido Pampaloni
- University of Pisa
- Dipartimento di Chimica e Chimica Industriale
- I-56124 Pisa
- Italy
| | - Stefano Zacchini
- University of Bologna
- Dipartimento di Chimica Industriale “Toso Montanari”
- I-40136 Bologna
- Italy
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19
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Bortoluzzi M, Marchetti F, Pampaloni G, Zacchini S. Oxido-molybdenum complexes obtained by Cl/O interchange between MoCl5 and carboxylic acids: a crystallographic, spectroscopic and computational study. Dalton Trans 2014; 43:16416-23. [PMID: 25251728 DOI: 10.1039/c4dt02201g] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The direct interaction of MoCl5 with a series of carboxylic acids has been elucidated for the first time. The reactions proceed with release of hydrogen chloride and Cl/O interchange between the metal centre and one equivalent of organic substrate: this feature is unique in the context of the chemistry generally shown by transition metal halides with carboxylic acids. The dinuclear complexes [MoOCl2(κ(1)-CX3CO2H)(μ-Cl)]2 (X = H, 1a; X = Cl, 1b) and Mo2O2Cl6(μ-CH3CO2H), 2a, were isolated as the prevalent metal products of the 1:2 molar reactions of MoCl5 with CH3COOH and CCl3COOH. Evidence for the formation of Mo2O2Cl6(μ-CCl3CO2H), 2b, was achieved by allowing MoCl5 to react with CCl3COOH in 2:3 ratio. Instead the reactions of MoCl5 with a three-fold molar excess of RCOOH afforded the mononuclear complexes MoOCl3(κ(1)-RCO2H)2 (R = CH3, 3a; CCl3, 3b; CHCl2, 3c; CMe3, 3d) in 50–60% yields. The new compounds were characterized by analytical and spectroscopic techniques, moreover the X-ray molecular structures were ascertained for 1a, 1b and 2a; 1a and 1b display single Mo–Mo bond. DFT calculations were carried out in order to shed light into structural aspects.
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Affiliation(s)
- Marco Bortoluzzi
- University of Venezia Ca' Foscari, Dipartimento di Scienze Molecolari e Nanosistemi, Dorsoduro 2137, I-30123 Venezia, Italy
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20
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Favero L, Marchetti F, Pampaloni G, Zacchini S. The interaction of molybdenum pentachloride with O- and S-heterocycles. Dalton Trans 2014; 43:495-504. [DOI: 10.1039/c3dt52271g] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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