Investigation into diphosphine oxides as ligands in diorganotin(IV) adducts. Part 1. Synthesis and spectroscopic characterization of 1,2-bis(diphenylphosphoryl)ethane tin complexes and X-ray structure of [1,2-bis(diphenylphosphoryl)ethane]di-n-butyldichlorotin(IV)

1,2-Bis(diphenylphosphoryl)ethane (dppoe) forms complexes with diorganotin(IV) chlorides of the type SnR2Cl2(dppoe)(R = Prn, Bun, or Ph), the i.r. and tin-119 Mossbauer spectra of which have been recorded. The crystal structure of SnBun2Cl2(dppoe) has been determined from single-crystal X-ray data collected by counter methods and refined by full-matrix least-squares techniques to R= 0.0461 for 2 430 observed reflections. Crystals are triclinic, space group P, with unit-cell dimensions a= 11.775(5), b= 15.987(7), c= 11.006(5)A, α= 102.12(5), β= 114.55(6), γ= 101.69(5)°, and Z= 2. Tin is bonded to two Cl– ions, to two C atoms and to two O atoms, to one more loosely than the other. The weaker co-ordination of one of the two OP groups is also reflected in distortions of the geometry of the co-ordination polyhedron. The structure is polymeric in that the dppoe ligand forms bridges between adjacent tin atoms. Tin-119 Mossbauer spectra have been recorded for the three SnR2Cl2(dppoe) complexes in the temperature range 77–150 K, and for the complex (SnPh3Cl)2(dppoe) at 77 K. Quadrupole-splitting data for the former are consistent with a trans-SnC2X4 arrangement about the tin atom in each case. Recoil-free fraction temperature coefficients, a, have also been determined for the three SnR2Cl2 complexes; root-mean-square amplitudes of vibration, 〈x〉, and absolute recoil-free fractions, ƒ, have been estimated at various temperatures for SnBun2Cl2(dppoe).