The crystal structure of a compound containing tin(IV) in both 5-fold and 6-fold co-ordination: [(CH3)2SnCl,terpyridyl]+[(CH3)2SnCl3]–

Abstract

A three-dimensional X-ray crystal structure analysis of the compound of composition (CH₃)₄Sn₂Cl₄, terpyridyl has established that it is monochlorobismethyl-2,2′,2″-terpyridyltin(IV) trichlorobismethylstannate(IV). The crystals are triclinic, space group P with a= 15·71, b= 10·04, c= 10·30 Å, α= 67·7°, β= 115·9°, γ= 119·6°. There are two formula units per unit cell, observed and calculated densities being 1·75 and 1·80 g.cm.^–1. 1589 photographically measured intensities were included in a full-matrix least-squares refinement which led to a conventional R of 13%. In the cations, the tin atom is bonded to a highly distorted octahedral arrangement of two trans-methyl groups, three nitrogen atoms, and a chlorine atom. The Sn–Cl bond length of 2·65(1)Å is the greatest yet encountered. The anions are trigonal bipyramidal with both methyl groups equatorial and subtending an angle of 140° at the tin atoms. Sn–Cl bond lengths in the anion are 2·32(1)Å(equatorial) and a mean of 2·54(2)Å(axial).