The ring-form dimer tris(o-methylbenzyl)tin hydroxide has been synthesized. The crystal structure of the complex was determined by X-ray diffraction, which belongs to a triclinic space group P-1 with: a＝1.00530(18) nm, b＝1.03580(18) nm, c＝1.08182(18) nm, α＝90.151(3)°, β＝108.317(3)°, γ＝94.871(3)°, V＝1.0650(3) nm3, Z＝1, Dc＝1.380 g/cm3, m(Mo Kα)＝0.1205 cm－1, F(000)＝451, R1＝0.0330 and Rw＝0.0822. In this compound, the tin atom is five-coordinated in a distorted trigonal bipyramid geometry, and the planar four-membered ring structure is shaped by Sn2O2. The stabilities of the complex, the orbital energies and composition characteristics of some frontier molecular orbitals have been investigated by means of G98W package and taking Lanl2dz basis set.

Key words: synthesis, crystal structure, ab initio method, tris(o-methylbenzyl)tin hydroxide