TRIMETHYL- AND TRICHLOROSILYLCOBALT TETRACARBONYLS AND HYDROSILATION OF ETHYLENE

The new compound (CH3)3SiCo(CO)4 was synthesized by the reaction of (CH3)3SiH with either Co2(CO)8 or HCo-(CO)4. The interaction of Cl3SiH or CH3SiH3 with HCo(CO)4 yielded Cl3SiCo(CO)4 and CH3SiH2Co(CO)4, respectively. The new compound [(CH3)2AsCo(CO)3]x was synthesized from (CH3)2AsH and HCo(CO)4 in an analogous manner. The thermal stability of the compounds R3SiCo(CO)4 (R = CH3, Cl) was examined. The silicon-cobalt bond in (CH3)3- SiCo(CO)4 was cleaved by water, methanol, dimethylamine, germanium tetrafluoride, and dimethylchloroarsine but not by phosphorus trifluoride, phosphorus pentafluoride, boron trifluoride, or acetyl chloride. The silicon-cobalt bond in Cl3SiCo(CO)4 was cleaved by iodine but not by phosphorus pentafluoride or ethyl iodide. Trimethylsilane, (CH3)3SiH, was found to add rapidly to ethylene at room temperature in the presence of catalytic quantities of HCo(CO)4 to give high yields of (CH3)3SiC2H5. Hydrosilation did not occur in the gas phase or when (CH3)3SiH was added to the products of the reaction of HCo(CO)4 with ethylene. The mechanism of the hydrosilation reaction is discussed. Neither (CH3)2AsH nor AsH3 added to ethylene in the presence of HCo(CO)4 when the reactants were treated in the manner necessary for hydrosilation of ethylene. © 1969, American Chemical Society. All rights reserved.