%0 Generic %A Samantaray, Manoja K. %A Shaikh, Mobin M. %A Ghosh, Prasenjit %D 2009 %T Rare [(NHC)2Ni-OH]-Type Terminal Nickel Hydroxo and [(NHC)2Ni]-Type Complexes of N/O-Functionalized N-Heterocyclic Carbenes as Precatalysts for Highly Desirable Base-Free Michael Reactions in Air at Ambient Temperature %U https://acs.figshare.com/articles/dataset/Rare_NHC_sub_2_sub_Ni_OH_Type_Terminal_Nickel_Hydroxo_and_NHC_sub_2_sub_Ni_Type_Complexes_of_i_N_i_i_O_i_Functionalized_N_Heterocyclic_Carbenes_as_Precatalysts_for_Highly_Desirable_Base_Free_Michael_Reactions_in_Air_at_Ambient_Temperature/2864887 %R 10.1021/om801186f.s003 %2 https://acs.figshare.com/ndownloader/files/4562716 %K nickel complexes %K 2 b %K 4 b %K 2CO %K Compounds 3 b %K NHC %K imidazolium chloride salts %X Highly convenient base-free Michael reaction of β-dicarbonyl, β-keto ester, and α-cyano ester compounds with activated ethylene compounds in air at ambient temperature catalyzed by a series of new nickel complexes, 1b4b, of N/O-functionalized N-heterocyclic carbenes (NHC) are reported. Quite interestingly, of these nickel complexes, 1b and 2b were found to be of the [(NHC)2Ni-OH] type bearing a terminal [Ni-OH] moiety and are among the few known structurally characterized examples of monomeric terminal [Ni-OH] complexes. Compounds 3b and 4b, on the other hand, were found to be of the commonly encountered [(NHC)2Ni]-type complexes. More significantly, both the [(NHC)2Ni-OH]-type complexes 1b and 2b and the [(NHC)2Ni]-type complexes 3b and 4b were synthesized using same synthetic methodology by sheer modulation of the N-substituents on the N-heterocyclic carbene ring by the reaction of the imidazolium chloride salts with NiCl2·6H2O in the presence of K2CO3 as a base. %I ACS Publications