Studies of some organo-nitrogen three-electron ligands in transition metal carbonyl complexes

Abstract

The work to be described is a continuation of the study of organo-nitrogen-transition metal complexes with particular reference to ketimino and related derivatives. Earlier work by colleagues has shown that the nature of the product formed from the reaction of π-C(_5)H(_5)M(CO)(_3)Cl,[I] (M= Mo,W), with lithio-ketimines, R(_2)C:NLi, depends on the group R. Thus for R = Ph, the product is the aza-allyl/allene derivative π-C(_5)H(_5)M(CO)(_2)[Ph(_2)CNCPh(_2)] and for R = Bu(^t), the ketimino complex π-C(_5)H(_5)M(CO)(_2)NCBu(^t)(_2)is formed. Reaction of [I] with (p-tolyl)(_2)C:NLi, however, produced three types of complex, π-C(_5)H(_5)M(CO)(_2)NC(P-TOLYL)(_2)[ll], π-C(_5)H(_5)M(C0)(_2)[(P-tolyl)(_2)CNC-(P-Tolyl)(_2)] [III], and K-CgH^M(C0)2[(2-tolyl)2CNC(2-l:olyl)2](2-tolyl)2C:0 [IV]. Two forms of [III], (M = W) were isolated in the solid state but a common species was formed in solution. [IV]also gave the same solution species together with the free ketone. A mechanism for the formation of the complexes and the biproducts (P-tolyl)2C:0, NCO" and CN~ is proposed. All complexes failed to undergo substitution reactions with PPh^ and reaction of iodine with [II] caused total decomposition of the complex. Dimerisation of [II] to [rt-C^H^M(C0)NC(P-tolyl)2] could be achieved for M = W, but not for M = Mo.Reaction of [l] with RgCiNLi in the presence of RgCiO (R = Ph, P-tolyl) resulted in formation of the complexes jt-C^H^M(CO)2NCR2 to the exclusion of the aza-allyl/allene complexes, which are formed in the absence of R(_2)C:O. The possible role of the ketone in the reaction is discussed.