X-Ray crystal structure analysis, nuclear magnetic resonance and Mössbauer parameters of trans-tetrachlorobis(triethylphosphine)tin(IV)

Abstract

Crystals of the title compound are monoclinic, space group P2₁/_n with Z= 2 in a cell of dimensions a= 7·189(8), b= 12·053(15), c= 12·028(14)Å, β= 91° 10′(20). The structure was solved by Patterson and Fourier methods and refined by full-matrix least-squares techniques to R 9·9% for 1206 visually estimated reflections. The centro-symmetric molecules have bond angles at tin within 1·3° of 90°; Sn–P is 2·615(5)Å, and Sn–Cl are 2·445(5) and 2·455(5)Å. The bond lengths are compared with those in phosphine complexes of transition- and Group B metal chlorides. The results are consistent with an earlier suggestion from Mössbauer studies that the Sn–P bonds have high tin 5s-character, and an approximate analysis of Sn–P r.m.r. coupling constants further supports this. An explanation is offered for the different modes of variation of ¹J(M–P) for complexes of the phosphines R_nPh_n–3P.