The reactivity of the silicon-hydrogen bond in a variety of silanes can be exploited in convenient syntheses for several silicon-centered heterometallic clusters. These syntheses, previously described,' are more usefully applied to clusters involving the odd-numbered transition metals. The isosteric identity of H3SiMn(CO)5 and H3PCr(CO)5 suggested the possibilities of synthesizing phosphorus-centered heterometallic clusters incorporating even-numbered transition metals. Syntheses obviously could be effected in reactions analogous to the reactions of isosteric silanes if the phosphorus-hydrogen bond displayed similar chemical reactivity. Such a possibility is indicated in a reaction reported by Hieber and Winter?(1) /PH% 2V(CO), + 2PH, .+ (CO),VT I The evolution of hydrogen in this reaction has its parallel in silane chemistry already mentioned.'
Results and DiscussionThe treatment of a tetrahydrofuran solution of pentacarbonylphosphinochromium, H3PCr(C0)5, with a deficiency of cobalt octacarbonyl, C O~( C O )~, results in a steady evolution of a mixture of hydrogen and carbon monoxide. The reaction H,PCr(CO), + Co,(CO), -L HPCrCo,(CO),, + H, + 2CO(2) is complete after 60 h at room temperature. The amount of pentacarbonylphosphinochromium remaining after completion is consistent with the equation given. The yield of product I is quantitative. The dark red crystalline solid I is quite soluble in methylene chloride and tetrahydrofuran, yet only sparingly soluble in n-hexane. The new compound is indefinitely stable in vacuo at room temperature and does not visibly change upon exposure to air for short periods of time. It is apparently slightly volatile in vacuo at elevated temperatures but decomposes at temperatures in excess of 90 OC as evidenced by the deposition of a metallic mirror on the walls of the reaction vessel. The volatile products of this decomposition have yet to be examined.It is of interest that the infrared spectrum of this new cluster does not indicate the presence of any bridging carbonyl ligands, especially so since the mott closely similar known siliconcentered cluster, p-pentacarbonylchlorosilyl-p-carbonylbis(tricarbonyl)cobalt, C1[ Mn(CO)5]SiCoz(CO)7, involves such V(CO), + H, + 4CO PH, I
