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Jabłoński M. Halogen Bond to Experimentally Significant N-Heterocyclic Carbenes (I, IMe 2, I iPr 2, I tBu 2, IPh 2, IMes 2, IDipp 2, IAd 2; I = Imidazol-2-ylidene). Int J Mol Sci 2023; 24:ijms24109057. [PMID: 37240403 DOI: 10.3390/ijms24109057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 05/15/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
The subjects of the article are halogen bonds between either XCN or XCCH (X = Cl, Br, I) and the carbene carbon atom in imidazol-2-ylidene (I) or its derivatives (IR2) with experimentally significant and systematically increased R substituents at both nitrogen atoms: methyl = Me, iso-propyl = iPr, tert-butyl = tBu, phenyl = Ph, mesityl = Mes, 2,6-diisopropylphenyl = Dipp, 1-adamantyl = Ad. It is shown that the halogen bond strength increases in the order Cl < Br < I and the XCN molecule forms stronger complexes than XCCH. Of all the carbenes considered, IMes2 forms the strongest and also the shortest halogen bonds with an apogee for complex IMes2⋯ICN for which D0 = 18.71 kcal/mol and dC⋯I = 2.541 Å. In many cases, IDipp2 forms as strong halogen bonds as IMes2. Quite the opposite, although characterized by the greatest nucleophilicity, ItBu2 forms the weakest complexes (and the longest halogen bonds) if X ≠ Cl. While this finding can easily be attributed to the steric hindrance exerted by the highly branched tert-butyl groups, it appears that the presence of the four C-H⋯X hydrogen bonds may also be of importance here. Similar situation occurs in the case of complexes with IAd2.
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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Torun, Poland
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Nature of Beryllium, Magnesium, and Zinc Bonds in Carbene⋯MX 2 (M = Be, Mg, Zn; X = H, Br) Dimers Revealed by the IQA, ETS-NOCV and LED Methods. Int J Mol Sci 2022; 23:ijms232314668. [PMID: 36498996 PMCID: PMC9738500 DOI: 10.3390/ijms232314668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 11/21/2022] [Accepted: 11/22/2022] [Indexed: 11/25/2022] Open
Abstract
The nature of beryllium−, magnesium− and zinc−carbene bonds in the cyclopropenylidene⋯MX2 (M = Be, Mg, Zn; X = H, Br) and imidazol-2-ylidene⋯MBr2 dimers is investigated by the joint use of the topological QTAIM-based IQA decomposition scheme, the molecular orbital-based ETS-NOCV charge and energy decomposition method, and the LED energy decomposition approach based on the state-of-the-art DLPNO-CCSD(T) method. All these methods show that the C⋯M bond strengthens according to the following order: Zn < Mg << Be. Electrostatics is proved to be the dominant bond component, whereas the orbital component is far less important. It is shown that QTAIM/IQA underestimates electrostatic contribution for zinc bonds with respect to both ETS-NOCV and LED schemes. The σ carbene→MX2 donation appears to be much more important than the MX2→ carbene back-donation of π symmetry. The substitution of hydrogen atoms by bromine (X in MX2) strengthens the metal−carbene bond in all cases. The physical origin of rotational barriers has been unveiled by the ETS-NOCV approach.
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Jabłoński M. Theoretical Study of N-Heterocyclic-Carbene-ZnX 2 (X = H, Me, Et) Complexes. MATERIALS 2021; 14:ma14206147. [PMID: 34683739 PMCID: PMC8539904 DOI: 10.3390/ma14206147] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/24/2021] [Accepted: 10/12/2021] [Indexed: 11/16/2022]
Abstract
This article discusses the properties of as many as 30 carbene–ZnX2 (X = H, Me, Et) complexes featuring a zinc bond C⋯Zn. The group of carbenes is represented by imidazol-2-ylidene and its nine derivatives (labeled as IR), in which both hydrogen atoms of N-H bonds have been substituted by R groups with various spatial hindrances, from the smallest Me, iPr, tBu through Ph, Tol, and Xyl to the bulkiest Mes, Dipp, and Ad. The main goal is to study the relationship between type and size of R and X and both the strength of C⋯Zn and the torsional angle of the ZnX2 plane with respect to the plane of the imidazol-2-ylidene ring. Despite the considerable diversity of R and X, the range of dC⋯Zn is quite narrow: 2.12–2.20 Å. On the contrary, D0 is characterized by a fairly wide range of 18.5–27.4 kcal/mol. For the smallest carbenes, the ZnX2 molecule is either in the plane of the carbene or is only slightly twisted with respect to it. The twist angle becomes larger and more varied with the bulkier R. However, the value of this angle is not easy to predict because it results not only from the presence of steric effects but also from the possible presence of various interatomic interactions, such as dihydrogen bonds, tetrel bonds, agostic bonds, and hydrogen bonds. It has been shown that at least some of these interactions may have a non-negligible influence on the structure of the IR–ZnX2 complex. This fact should be taken into account in addition to the commonly discussed R⋯X steric repulsion.
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Affiliation(s)
- Mirosław Jabłoński
- Faculty of Chemistry, Nicolaus Copernicus University in Toruń, Gagarina 7, 87-100 Toruń, Poland
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Specklin D, Fliedel C, Dagorne S. Recent Representative Advances on the Synthesis and Reactivity of N-Heterocyclic-Carbene-Supported Zinc Complexes. CHEM REC 2021; 21:1130-1143. [PMID: 33792152 DOI: 10.1002/tcr.202100041] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Revised: 03/12/2021] [Indexed: 12/21/2022]
Abstract
The present account reviews the most recent noteworthy developments on the synthesis, structure and catalytic applications of Zn-NHC species, a class of complexes that have attracted attention over the past five to ten years due to their enhanced robustness and hydrolytic stability versus classical Zn organometallics. In particular, thanks to NHC stabilization, access to unprecedented Zn species were recently achieved, including two-coordinate Zn(II) organocations and thermally stable molecularly well-defined Zn hydride species, opening the way to effective Zn-mediated hydro-silylation/-boration catalysis of various unsaturated substrates under mild conditions. The potential of NHC-Zn species for the stabilization of unprecedented Zn species and use in various catalytic applications is only emerging and the vast array of readily available NHC structures should promote future developments of the field.
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Affiliation(s)
- David Specklin
- Institut de Chimie (UMR CNRS 7177), Université de Strasbourg, 4, rue Blaise Pascal, 67000, Strasbourg, France
| | - Christophe Fliedel
- Institut de Chimie (UMR CNRS 7177), Université de Strasbourg, 4, rue Blaise Pascal, 67000, Strasbourg, France
| | - Samuel Dagorne
- Institut de Chimie (UMR CNRS 7177), Université de Strasbourg, 4, rue Blaise Pascal, 67000, Strasbourg, France
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Quinlivan PJ, Shlian DG, Amemiya E, Parkin G. Reactivity of the carbodiphosphorane, (Ph 3P) 2C, towards main group metal alkyl compounds: coordination and cyclometalation. Dalton Trans 2019; 48:9139-9151. [PMID: 31145405 DOI: 10.1039/c9dt00678h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The carbodiphosphorane, (Ph3P)2C, reacts with Me3Al and Me3Ga to afford the adducts, [(Ph3P)2C]AlMe3 and [(Ph3P)2C]GaMe3, which have been structurally characterized by X-ray diffraction. (Ph3P)2C also reacts with Me2Zn and Me2Cd to generate an adduct but the formation is reversible on the NMR time scale. At elevated temperatures, however, elimination of methane and cyclometalation occurs to afford [κ2-Ph3PC{PPh2(C6H4)}]ZnMe and [κ2-Ph3PC{PPh2(C6H4)}]CdMe. Analogous cyclometalated products, [κ2-Ph3P{CPPh2(C6H4)}]ZnN(SiMe3)2 and [κ2-Ph3P{CPPh2(C6H4)}]CdN(SiMe3)2, are also obtained upon reaction of (Ph3P)2C with Zn[N(SiMe3)2]2 and Cd[N(SiMe3)2]2. The magnesium compounds, Me2Mg and {Mg[N(SiMe3)2]2}2, likewise react with (Ph3P)2C to afford cyclometalated derivatives, namely [κ2-Ph3PC{PPh2(C6H4)}]MgN(SiMe3)2 and {[κ2-Ph3PC{PPh2(C6H4)}]MgMe}2. While this reactivity is similar to the zinc system, the magnesium methyl complex is a dimer with bridging methyl groups, whereas the zinc complex is a monomer. The greater tendency of the methyl groups to bridge magnesium centers rather than zinc centers is supported by density functional theory calculations.
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Affiliation(s)
- Patrick J Quinlivan
- Department of Chemistry, Columbia University, New York, New York 10027, USA.
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Rittinghaus RD, Schäfer PM, Albrecht P, Conrads C, Hoffmann A, Ksiazkiewicz AN, Bienemann O, Pich A, Herres-Pawlis S. New Kids in Lactide Polymerization: Highly Active and Robust Iron Guanidine Complexes as Superior Catalysts. CHEMSUSCHEM 2019; 12:2161-2165. [PMID: 30811863 DOI: 10.1002/cssc.201900481] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 02/25/2019] [Indexed: 06/09/2023]
Abstract
Polylactide is a biodegradable versatile material based on annually renewable resources and thus CO2 -neutral in its lifecycle. Until now, tin(II)octanoate [Sn(Oct2 )] was used as catalyst for the industrial ring-opening polymerization of lactide in spite of its cytotoxicity. On the way towards a sustainable catalyst, three iron(II) hybrid guanidine complexes were investigated concerning their molecular structure and applied to the ring-opening polymerization of lactide. The complexes could polymerize unpurified technical-grade rac-lactide as well as recrystallized l-lactide to long-chain polylactide in bulk with monomer/initiator ratios of more than 5000:1 in a controlled manner following the coordination-insertion mechanism. For the first time, a biocompatible complex has surpassed Sn(Oct)2 in its polymerization activity under industrially relevant conditions.
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Affiliation(s)
- Ruth D Rittinghaus
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Pascal M Schäfer
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Pascal Albrecht
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Christian Conrads
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Alexander Hoffmann
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
| | - Agnieszka N Ksiazkiewicz
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
- Leibniz-Institute for Interactive Materials (DWI), Forckenbeckstraße 50, 52074, Aachen, Germany
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD, Geleen, The Netherlands
| | - Olga Bienemann
- Fakultät für Chemie und chemische Biologie, Technische Universität Dortmund, Otto-Hahn-Straße 6, 44227, Dortmund, Germany
| | - Andrij Pich
- Institute of Technical and Macromolecular Chemistry, RWTH Aachen University, Worringerweg 2, 52074, Aachen, Germany
- Leibniz-Institute for Interactive Materials (DWI), Forckenbeckstraße 50, 52074, Aachen, Germany
- Aachen Maastricht Institute for Biobased Materials (AMIBM), Maastricht University, Brightlands Chemelot Campus, Urmonderbaan 22, 6167 RD, Geleen, The Netherlands
| | - Sonja Herres-Pawlis
- Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52074, Aachen, Germany
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Procter RJ, Uzelac M, Cid J, Rushworth PJ, Ingleson MJ. Low-Coordinate NHC–Zinc Hydride Complexes Catalyze Alkyne C–H Borylation and Hydroboration Using Pinacolborane. ACS Catal 2019. [DOI: 10.1021/acscatal.9b01370] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
| | - Marina Uzelac
- School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, U.K
| | - Jessica Cid
- School of Chemistry, University of Manchester, Manchester M13 9PL, U.K
| | - Philip J. Rushworth
- Research and Development, GlaxoSmithKline, Gunnels Wood Road, Stevenage SG1 2NY, U.K
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Goszczycki P, Stadnicka KM, Musielak B, Ostrowska K. Cobalt(II), copper(II), and zinc(II) isostructural, pseudotetrahedral, racemic complexes of pyrrolo[2,3-b]quinoxaline with bis(2-thienylmethyl)propylenediamine chain: Synthesis, crystal structure, spectroscopy. Polyhedron 2019. [DOI: 10.1016/j.poly.2018.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Han Y, Gao A, Zhang Y, Yao W, Guan H. Zinc complexes supported by N,O-bidentate amino-alkoxyl ligands: Synthesis, characterization and catalytic property for the ring-opening polymerization of l-lactide. Polyhedron 2018. [DOI: 10.1016/j.poly.2017.10.038] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Aluminum complexes with benzoxazolphenolate ligands: Synthesis, characterization and catalytic properties for ring-opening polymerization of cyclic esters. Polyhedron 2016. [DOI: 10.1016/j.poly.2016.03.042] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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