Reactions of nickel-group 6 complexes with a bulky terminal alkyne to afford alkyne-carbonyl coupled products: X-ray structure of the heterobimetallic nickelacyclobutenone complex [(eta(5)-C5Me5)Ni{mu-eta(1), eta(3)-C(H)=C(CPh2(OMe))-C(O)}-I Mo(CO)(2

摘要

The nickel-molybdenum complex [(eta(5)-C5Me5)Ni=Mo(CO)(3)(eta(5)-C5H4Me)] can be considered to contain a partially dative nickelmolybdenum double bond. This complex reacts with the bulky terminal alkyne HC CCPh2(OMe) (DPMP) to afford the alkyne-carbonyl coupled metallacyclic product [(eta(5)-C5Me5)Ni{(mu-CH=CR-C(O)(2)Mo(CO)(2)(eta(5)-C5H4Me)] (3c, R = CPh2(OMe), Ni-Mo) regioselectively and exclusively. No traces of a nickel-molybdenum mu-alkyne complex, analogous to similar complexes isolated with less bulky alkynes, were observed. The structure of complex 3c was established via a single crystal X-ray diffraction study. It exhibits the same connectivity as that observed with a related complex formed with the smaller but-2-yne, but some significant differences are observed between the two structures. Reactions of the nickel-molybdenum and -tungsten species [(eta(5) -C5Me5)Ni=M(CO)(3)(eta(5) -C5H5)] (M = Mo, W) with DPMP proceeded analogously and afforded similar products. (c) 2007 Elsevier B.V. All rights reserved.