Cyanoacetylenes and cyanoacetylides: versatile ligands in organometallic chemistry
Abstract
The CC
N (1) has been found to coordinate readily to the Ru(PPh3)2Cp fragment, to give [Ru(N
CC
CPh)(PPh3)2Cp]PF6
(2) which may be considered as an “extended” derivative of the more common
CPh)(PPh3)2Cp]PF6
(3). Reaction of 1 with [Co2(CO)6(dppm)] readily forms the μ,η2 complex [Co2(μ,η2-PhC2C
N)(CO)4(dppm)]
(4), which reacts with [RuCl(PPh3)2Cp] to give the mixed metal species [{Co2(μ,η2-PhC2C
N){Ru(PPh3)2Cp}(CO)4(μ-dppm)}]PF6
(5). The η1(N) bonded PhC
CC
N
CC
N)(PPh3)2Cp]
(6) was prepared by lithiation (BuLi) of [Ru(C
CH)(PPh3)2Cp] followed by treatment with PhOCN. Coordination of the metal fragments Ru(PPh3)2Cp or Fe(dppe)Cp to the N terminus in 6 occurs readily to give the homo- or hetero-bimetallic
CC
N){ML2Cp}]+, which were isolated as the PF6 salts [ML2Cp = Ru(PPh3)2Cp (7); Fe(dppe)Cp (8)]. The crystal structures of 2–5, 7 and 9 are reported. The electrochemical response of these complexes suggests there are considerable electronic interactions between the heterometallic end-caps in 8 through the polarised C3N bridge.