SYNTHESIS OF THE SQUARE-BIPYRAMIDAL CLUSTER [CO4(MU-4-SIME)2(CO)11] BY 2 ROUTES AND ITS REACTION WITH GEME2H2 - THE CRYSTAL-STRUCTURES OF [CO4(MU-4-SIME)2(CO)11] AND [CO4(MU-4-SIME)2(MU-GEME2)(CO)10]

[Co4(mu4-SiMe)2(CO)11] (1a) is the major product from the reaction of [CO2(CO)8] with [Fe(SiMeH2)2(CO)4] (synthesised from SiMeH2Cl and Na2[Fe(CO)4]). An alternative, quantitative synthesis of la is from SiMeH3 and [Co4(CO)12]. 1a reacts with an equimolar amount of GeMe2H2 to form in high yield [Co4(mu4-SiMe)2{mu-GeMe2}(CO)10] (2), in which the mu-GeMe2 group has replaced the bridging carbonyl of the parent compound. Molecular structures were determined for la and 2.