[Bis(diphenylphosphino)methane][mu,eta(2)-bis(trimethylstannyl)acetylene]tetracarbonyldicobalt

The title compound, [Co-2(C25H22P2)(C8H18Sn2)(CO)(4)], was prepared by disp lacement of two molecules of carbon monoxide in hexacarbonyldicobalt[mu,eta (2)-bis-(trimethylstannyl)]acetylene with a bidentate bis(diphenylphosphin o)-methane ligand. The displacement of carbon monoxide yields the product w ith substantially increased thermal stability and brings about noticeable c hanges in the geometry of the dicobaltatetrahedrane moiety, viz. lengthenin g of the carbon-carbon bond and shortening of the cobalt-cobalt and cobalt- carbon bonds.