Department of Chemistry, Moscow State University, Moscow 117234 U.S.S.R.;Lensouet Leningrad Technological Institute, Leningrad 198013 U.S.S.R.
Abstract:
The geometrical parameters of the tetraphenyltin molecule have been determined by gas phase electron diffraction at about 310°. The S4 and “open” D2d molecular models with the tetrahedral bond configuration at tin were chosen for the structure analysis. The former gave the better fit. The thermal average bond lengths (rg, in Å) are as follows: The benzene ring geometry appears to be almost unaffected by bonding to tin. However, tin causes an increase in the endocyclic valence angle at the ipso-carbon atom to 121.0(0.9)° rather than a decrease of that angle as might be expected, tin being a σ-electron donor. The ring plane and the plane containing the bond and S4 axis make an angle, ?, of 34.1(2.1)°. The bond length in tetraphenyltin is longer than not only the bond in tetravinyltin (rg = 2.117(4) Å) but also the bond in tetramethyltin (rg = 2.144(7) A).