Electron-diffraction Investigation of the Molecular Structure of Tetramethyltin

The structure parameters of tetramethyltin have been determined by gas-phase electron diffraction to be as follows: rg(Sn–C)=2.1436±0.0030 A, rg(Sn···H)=2.7642±0.0125 A, rg(C–H)=1.1179±0.0090 A, l(Sn–C)=0.0496±0.0098 A, and l(Sn···H)=0.1532±0.0132 A. The experimental molecular intensity has been well reproduced by the molecular model in which the methyl groups are rotating freely, or nearly freely. The scattering factors, based upon the relativistic Hartree-Fock-Slater or the Hartree-Fock atomic potential, have given a theoretical background in better agreement with the experimental one and have led to a more reasonable Sn–C mean amplitude than did the scattering factors based upon the Thomas-Fermi-Dirac or the Thomas-Fermi atomic potential.