1,2,4-Triazol-3-ylidenes with anN-2,4-Dinitrophenyl Substituent as Strongly π-Accepting N-Heterocyclic Carbenes
摘要:
AbstractThe synthesis and characterisation of a series of new Rh and Au complexes bearing 1,2,4‐triazol‐3‐ylidenes with a N‐2,4‐dinitrophenyl (N‐DNP) substituent are described. IR, NMR, single‐crystal X‐ray diffraction and computational analyses of the Rh complexes revealed that the N‐heterocyclic carbenes (NHCs) behaved as strong π acceptors and weak σ donors. In particular, a natural bond orbital (NBO) analysis revealed that the contributions of the Rh→Ccarbene π backbonding interaction energies (ΔEbb) to the bond dissociation energies (BDE) of the RhCcarbene bond for [RhCl(NHC)(cod)] (cod=1,5‐cyclooctadiene) reached up to 63 %. The Au complex exhibited superior catalytic activity in the intermolecular hydroalkoxylation of cyclohexene with 2‐methoxyethanol. The NBO analysis suggested that the high catalytic activity of the AuI complex resulted from the enhanced π acidity of the Au atom.
1,2,4-Triazol-3-ylidenes with anN-2,4-Dinitrophenyl Substituent as Strongly π-Accepting N-Heterocyclic Carbenes
摘要:
AbstractThe synthesis and characterisation of a series of new Rh and Au complexes bearing 1,2,4‐triazol‐3‐ylidenes with a N‐2,4‐dinitrophenyl (N‐DNP) substituent are described. IR, NMR, single‐crystal X‐ray diffraction and computational analyses of the Rh complexes revealed that the N‐heterocyclic carbenes (NHCs) behaved as strong π acceptors and weak σ donors. In particular, a natural bond orbital (NBO) analysis revealed that the contributions of the Rh→Ccarbene π backbonding interaction energies (ΔEbb) to the bond dissociation energies (BDE) of the RhCcarbene bond for [RhCl(NHC)(cod)] (cod=1,5‐cyclooctadiene) reached up to 63 %. The Au complex exhibited superior catalytic activity in the intermolecular hydroalkoxylation of cyclohexene with 2‐methoxyethanol. The NBO analysis suggested that the high catalytic activity of the AuI complex resulted from the enhanced π acidity of the Au atom.
Twelve N-aryl derivatives of 4-nitroimidazole, 2-methyl-4-nitroimidazole, 4-nitropyrazole or 3-nitro-1,2,4-triazole have been synthesized either by a degenerated ring transformation reaction of 1,4-dinitroimidazoles with 4-substituted anilines or by a condensation of fluoronitrobenzenes with salts prepared from C-nitro-1H-azoles and 1,8-diazabicyclo[5.4.0]-7-undecene. The Tuberculosis Antimicrobial Acquisition and Coordinating Facility has provided anti-mycobacterial data concerning inhibition activity of 12 compounds. (C) 2004 Elsevier SAS. All rights reserved.
1,2,4-Triazol-3-ylidenes with an<i>N</i>-2,4-Dinitrophenyl Substituent as Strongly π-Accepting N-Heterocyclic Carbenes
作者:Tetsuo Sato、Yoichi Hirose、Daisuke Yoshioka、Tsubasa Shimojo、Shuichi Oi
DOI:10.1002/chem.201302567
日期:2013.11.11
AbstractThe synthesis and characterisation of a series of new Rh and Au complexes bearing 1,2,4‐triazol‐3‐ylidenes with a N‐2,4‐dinitrophenyl (N‐DNP) substituent are described. IR, NMR, single‐crystal X‐ray diffraction and computational analyses of the Rh complexes revealed that the N‐heterocyclic carbenes (NHCs) behaved as strong π acceptors and weak σ donors. In particular, a natural bond orbital (NBO) analysis revealed that the contributions of the Rh→Ccarbene π backbonding interaction energies (ΔEbb) to the bond dissociation energies (BDE) of the RhCcarbene bond for [RhCl(NHC)(cod)] (cod=1,5‐cyclooctadiene) reached up to 63 %. The Au complex exhibited superior catalytic activity in the intermolecular hydroalkoxylation of cyclohexene with 2‐methoxyethanol. The NBO analysis suggested that the high catalytic activity of the AuI complex resulted from the enhanced π acidity of the Au atom.