Flash-Photolysis Studies of the Photochemical Reactions of Silanes with Chromium Hexacarbonyl

Article abstract of DOI:10.1021/ja00018a029

The photochemical reactions following flash photolysis of n-hexane solutions containing silanes and Cr(CO)6 have been studied.The silane adducts vary widely in stability.The kinetics of silane elimination from Cr(CO)5(silane) in hexane solutions under a CO atmosphere were investigated.For HSiClMe2 and HSiClPh2, two distinct first-order decay processes were observed, corresponding to elimination of H-Si- and Cl-Si-bonded adducts.Decay is faster for the Cl-Si form of bonding.The rates of elimination at 25 deg C were measured for a series of 14 silanes differing widely in steric and electronic properties.The stabilities of the Cr(CO)5(H-SiR'R2) adducts increase with increasing electron-donor character of the silane, the opposite order from that observed for (η⁵-C5H5)(CO)2Mn(silane) and other related systems.The reversal of order reflects the relatively greater importance of ? donation to the metal in bonding to the more electrophilic Cr metal center.