Silylene rearrangements in the reactions of recoiling silicon atoms with trimethylsilane

The exploration of atom-molecule reactions above their threshold energies is a major task of hot-atom chemists, and where comparisons have been made, the recoil reactions differ significantly from their thermal counterparts. This is the case for the reactions of recoiling silicon atoms with trimethylsilane. Free atoms were produced by the /sup 31/P(n,p)/sup 31/Si nuclear transformation induced in gaseous mixtures of phosphine and trimethlysilane by cyclotron-produced fast neutrons. The products detected are given in order of increasing vapor-chromatographic retention times. n + PH/sub 3/ ..-->.. p + /sup 31/Si + 3H; /sup 31/Si + HSiMe/sub 3/ ..-->../PH/sub 3/ /sup 31/SiH/sub 4/ (2%) + H/sub 3/ /sup 31/SiMe (0.5%) + unknown (0.1%) + H/sub 3/ /sup 31/SiSiMe/sub 3/ (36%) + MeH/sub 2/ /sup 31/SiSiMe/sub 3/ (10%) + unknown (5%) + Me/sub 3/Si /sup 31/SiH/sub 2/SiMe/sub 3/ (5%) + A (3%) 1. This communication attributes the formation of products 1 and A to silylene intermediates. A recently discovered rearrangement of silylenes has led to the identification of A and forms the basis for a mechanism that follows a /sup 31/Si atom from its initial reactive encounter with a HSiMe/sub 3/ molecule to 1 and A. (DP)