Alkynyl and butadiynyl complexes of the cycloheptatrienylmolybdenum auxiliary Mo(CO)(2)(eta-C7H7)

The new alkynyl complexes [Mo(C drop CR)(CO)(2)(eta-C-7-H-7)] (1, R = Bu'; 2, R = SiMe3; 3, R = CO2Et) have been prepared by reaction of [MoBr(CO)(2)( eta-C7H7)] with alkynyl lithium (1, 2) or alkynyl copper (3) reagents. The sigma-butadienyl complex [Mo{C(=C(CN)(2))C(Ph)=C(CN)(2)}(CO)(2)(eta-C7H7)] 6, is formed by reaction of [Mo(C drop CPh)(CO)(2)(eta-C7H7)] with tetracya noethene. Treatment of [MoBr(CO)2(eta-C7H7)] with LiC drop CC drop CSiMe3 a ffords [Mo(C drop CC drop CSiMe3)(CO)(2)(eta-C7H7)] 7 which is a precursor to [Mo(C drop CC drop CH)(CO)(2)(eta-C7H7)] 8 by desilylation with KF in me thanol/THF. The butadiynyl complexes [Mo(C drop CC drop CH)(CO)L(eta-C7H7)] (8, L = CO; 9, L = PMe3) are also formed directly by reaction of [MoBr(CO) L(eta-C7H7)] with Li2C drop CC drop C in THF. (C) 1999 Elsevier Science S.A . All rights reserved.