REACTIVITY OF COMPLEX-BOUND PHENYLETHYNYLCHLOROSILANES

The reaction of [(eta-2-C = CPh)Co2(CO)6](Me)Si(H)(Cl), III, with different substrates is described: III yield with 0.5 equivalents of Co2(CO)8, II, under oxidative addition, [(eta-2-C = CPh)Co2(CO)6](Me) Si[Co(CO)4](Cl), IV. IV may also be synthesized directly by reaction of (PhC = C)(Me)Si(H)(Cl), I, with 1.5 equivalents of Co2(CO)8. Treatment of III or IV with an excess of ROH (R = H, Me, Et) affords, in high yields, complex [(eta-2-C = CPh)Co2(CO)6](Me)Si(OR)2, V, in which the H and Cl groups in III are substituted by OR. However, the hydrolysis of III with one equivalent of H2O yields the disiloxane {[(eta-2-C = CPh)Co2(CO)6](Me)(H)Si}2O, VII. The formation of [(eta-2-C = CPh)Co2(CO)6](Me)Si(H)(OH), VI, as a reactive intermediate is discussed. Treatment of compound III with BrMgC = CPh affords [(eta-2-C = CPh)Co2(CO)6](PhC = C)Si(H)(Me), VIII. VIII reacts with further Co2(CO)8, II, to yield [(eta-2-C = CPh)Co2(CO)6]2Si(H)(Me), IX, in which each of the two phenylethynyl units is eta-2-side-on co-ordinated to "Co2(CO)6" to form dicobalta-tetrahedrane cluster units. [(eta-2-C = CPh)Co2(CO)6](PhC = C)Si(H)(Cl), XI, shows a similar reaction behaviour as III: With H2O selectively the silanol [(eta-2-C = CPh)Co2(CO)6](PhC = C)Si(H)(OH), XII, is formed, which upon reaction with one equivalent of Co2(CO)8, II, yields [(eta-2-C = CPh)Co2(CO)6]2Si(H)(OH), XIV. XIV may also be synthesized by treatment of XI with II, yielding in the first step [(eta-2-C = CPh)Co2(CO)6]2Si(H)(Cl), XIII. Hydrolysis of XIII in the second step then yields quantitatively XIV. All new compounds have been characterized by analytical and spectroscopic data (IR, H-1, C-13 NMR, MS).