Coordination Chemistry of Highly Hemilabile Bidentate Sulfoxide N‐Heterocyclic Carbenes with Palladium(II) |
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| Authors: | Dr. Kuo‐Hsuan Yu Chia‐Ching Wang Dr. I‐Hsin Chang Yi‐Hung Liu Prof. Dr. Yu Wang Prof. Dr. Cornelis J. Elsevier Prof. Dr. Shiuh‐Tzung Liu Prof. Dr. Jwu‐Ting Chen |
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| Affiliation: | 1. Department of Chemistry, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617 Taiwan (R.O.C.), Fax: (+886)?2‐2363‐6359;2. Van't Hoff Institute of Molecular Sciences, University of Amsterdam, Nieuwe Achtergracht 166, 1018 WV Amsterdam (The Netherlands) |
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| Abstract: | Imidazolium salts, [RS(O)? CH2(C3H3N2)Mes]Cl (R=Me ( L1 a ), Ph ( L1 b )); Mes=mesityl), make convenient carbene precursors. Palladation of L1 a affords the monodentate dinuclear complex, [(PdCl2{MeS(O)CH2(C3H2N2)Mes})2] ( 2 a ), which is converted into trans‐[PdCl2(NHC)2] (trans‐ 4 a ; N‐heterocyclic carbene) with two rotamers in anti and syn configurations. Complex trans‐ 4 a can isomerize into cis‐ 4 a (anti) at reflux in acetonitrile. Abstraction of chlorides from 4 a or 4 b leads to the formation of a new dication: trans‐[Pd{RS(O)CH2(C3H2N2)Mes}2](PF6)2 (R=Me ( 5 a ), Ph ( 5 b )). The X‐ray structure of 5 a provides evidence that the two bidentate SO? NHC ligands at palladium(II) are in square‐planar geometry. Two sulfoxides are sulfur‐ and oxygen‐bound, and constitute five‐ and six‐membered chelate rings with the metal center, respectively. In acetonitrile, complexes 5 a or 5 b spontaneously transform into cis‐[Pd(NHC)2(NCMe)2](PF6)2. Similar studies of thioether–NHCs have also been examined for comparison. The results indicate that sulfoxides are more labile than thioethers. |
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| Keywords: | carbenes coordination modes palladium sulfur structure elucidation |
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