A FURTHER STUDY OF THE REACTION OF METHYLGERMANE WITH [CO2(CO)8], AND SOME INTERCONVERSIONS OF THE PRODUCTS - CRYSTAL AND MOLECULAR-STRUCTURES OF [CO2(MU-GE(ME)CO(CO)4)(CO)7] AND [CO4(MU-4-GEME)2(MU-GE(ME)CO(CO)4)(CO)10], AND EDGE-BRIDGED SQUARE-BIPYRAMIDAL GE2CO4 SPECIES

The compound [CoH(CO)4] has been established as a stoichiometric product in the fast reaction of GeMeH3 with [Co2(CO)8] to form [Co2{mu-Ge(Me)Co(CO)4}(CO)7] 1. A prolonged reaction with an excess of GeMeH3 yields [Co2{mu-Ge(Me)Co(CO)4}2(CO)6] 2, accompanied by a hydride species [Co2(GeMeH)(CO)x](x = 7 or 8) when the excess is large. Heating this latter mixture yields [Co4(mu-4-GeMe)2{mu-Ge(Me)Co(CO)4}(CO)10] 3, shown by X-ray crystallography to contain the Co4(mu-4-GeMe)2 square-bipyramid core, edge-bridged by a mu-Ge(Me)[Co(CO)4] unit. The bridged Co atoms carry two terminal CO groups, and the non-bridged ones, three. The crystal structures of compound 1 [triclinic, space group P1BAR, Z = 2, a = 8.626(6), b = 8.656(5), c = 13.381(9) angstrom, alpha = 88.25(5), beta = 84.72(5), gamma = 66.26(4)-degrees, R = 0.0649 for 1614 reflections with I > 3-sigma-(I)] and 3 [monoclinic, space group C2/m, Z = 4, a = 12.330(6), b = 12.302(3), c = 18.815(9) angstrom, beta = 92.93(3)-degrees, R = 0.0344 for 1136 reflections with I > 3-sigma-(I)] have been determined and are compared with that of 2, and spectroscopic properties are discussed, including heavy-atom vibrations of 1.