Synthesis and characterization of new transition metal diynyl complexes

The reaction of (eta(5)-C5H5)Mo(CO)(dppe)Cl with LiC=CC=CSiMe3 yielded (eta (5)-C5H5)(CO)(dppe)MoC=CC=CSiMe3 (1b) and, as a by-product (eta(5)-C5H5)Mo( CO)(dppe)Br (1a). Treatment of 1b with 0.2 equivalents of tetrabutylammoniu m fluoride or (eta(5)-C5H5)Mo(CO)(dppe)Cl with HC=CC=CH gave the terminal b utadiyne complex (eta(5)-C5H5)(CO)(dppe)MoC=CC=CH (2). Complex 2 was deprot onated with sec-BuLi or lithium diisopropylamide, and the resulting anion ( eta(5)-C5H5)(CO)(dppe)MoC=CC=CLi (3) was trapped with Me3SiCl to regenerate 1b. The synthesis of Co-2(CO)(4)L-2(mu-eta(2)-Me3SiC2C=CSiMe3)(L-2 = dppa 4, 2PPh(2)Me 5) compounds can be achieved by two methods: from Co-2(CO)(6)( mu-dppa) by reaction with Me3SiC=CC=CSiMe3 in 1:1 ratio to yield 4, or from Co-2(CO)(6)(mu-eta(2)-Me3SiC2C=CSiMe3) by reaction with dppa (1:1 ratio) a nd PPh2Me (1:2 ratio) to yield 4 and 5, respectively. When the Co-2(CO)(4)( mu-dppa)(mu-eta(2)-Me3SiC2C=CSiMe3) complex was treated with more Co-2(CO)( 6)(mu-dppa) the green di-substituted complex [Co-2(CO)(4)(mu-dppa)](2)(mu-e ta(2):mu-eta(2)-Me3SiC2C2SiMe3) (6) was obtained. Desilylation of 4 with Bu 4NF gave Co-2(CO)(4)(mu-dppa)(mu-eta(2)-Me3SiC2C=CH) (7). All compounds syn thesized have been characterized by analytical and spectroscopic data (IR,H -1-, P-31-, C-13-NMR, MS). In addition, compounds la and 4 were characteriz ed by X-ray structure analysis. (C) 1999 Elsevier Science S.A. All rights r eserved.