Tin halogen compounds. 3. Recent data on crystal and molecular structure of dimethyl tin dichloride

The crystal structure of dimethyltin dichloride, Me2SnCl2, known for a long time, has been corrected by means of four-circle diffractometer data, beca use in comparison to other diorganotin dichlorides serious doubts about the molecular geometry came up. The new, corrected values confirm the old stru cture model but supply more reliable data in view of the molecular paramete rs. In particular, the following values have been found for distances and a ngles: d(Sn-C) = 212.0(7) pm, d(Sn-Cl)= 238.9(2)pm, angle (Cl-Sn-Cl) = 98.6 0(9)degrees, angle (C-Sn-C) = 142.2(4)degrees. The length of the intermolec ular tin . . . chlorine bridge was determined to 343.3 pm. This value shows that dimethyltin dichloride has a strong intermolecular association due to small sterical shielding of the tin atom by the methyl groups.