First gas-phase detection of dimethylstannylene and time-resolved study of some of its reactions

Using a laser flash photolysis/laser probe technique, we report the observation of strong absorption signals in the wavelength region 450-520 nm (highest intensity at 514.5 nm) from four potential precursors of dimethylstannylene, SnMe(2), subjected to 193 nm UV pulses. From GC analyses of the gaseous products, combined with quantum chemical excited state CIS and TD calculations, we can attribute these absorptions largely to SnMe(2), with SnMe(4) as the cleanest source of the species. Kinetic studies have been carried out by time-resolved monitoring of SnMe(2). Rate constants have been measured for its reactions with 1,3-C(4)H(6), MeC[triple bond]CMe, MeOH, 1-C(4)H(9)Br, HCl, and SO(2). No evidence could be found for reaction of SnMe(2) with C(2)H(4), C(3)H(8), Me(3)SiH, GeH(4), Me(2)GeH(2), or N(2)O. Limits of less than 10(-13) cm(3) molecule(-1) s(-1) were set for the rate constants for these latter reactions. These measurements showed that SnMe(2) does not insert readily into C-H, Si-H, Ge-H, C-C, Si-C, or Ge-C bonds. It is also unreactive with alkenes although not with dienes or alkynes. It is selectively reactive with lone pair donor molecules. The possible mechanisms of these reactions are discussed. These results represent the first visible absorption spectrum and rate constants for any organo-stannylene in the gas phase.