MOLECULAR-STRUCTURE OF 1,3,5-TRIS (TRIMETHYLSTANNYL) BENZENE - AN ELECTRON-DIFFRACTION STUDY

The molecular structure of 1,3,5-tris (trimethylstannyl) benzene has b een determined by gas-phase electron diffraction. The C-C bond length is in good agreement with that in benzene. In agreement with the somew hat electron-releasing character of the substituents, the endocyclic b ond angles at the substituents are somewhat smaller than 120 degrees. The mean value of Sn-C bond Lengths is greater than that in tetrapheny ltin and tetramethyltin. The SnMe3 groups appear freely rotating aroun d the C-aryl-Sn bonds. The following bond lengths (r(g)) and bond angl es were determined: (Sn-C)(mean) 2.150 +/- 0.007 Angstrom, C-C 1.399 /- 0.005 Angstrom, (C-H)(mean) 1.105 +/- 0.006 Angstrom, < C-C(Sn)-C 1 17.7 +/- 1.7 degrees, < C-aryl-Sn-C-methyl 106.7 +/- 0.7 degrees, < Sn -C-H 111.5 +/- 0.9 degrees.