Investigation into diphosphine oxides as ligands in diorganotin(IV) adducts. Part 2. Synthesis, spectroscopic characterization, and X-ray crystal structure of cis-1,2-bis(diphenylphosphoryl)ethylenetin complexes

Abstract

Organotin(IV) complexes of formula SnR₂Cl₂(dppoet)[dppoet =cis-1,2-bis(diphenylphosphoryl)ethylene; R = Buⁿ, Prⁿ, or Ph] have been synthesised and characterised by i.r. and tin-119 Mössbauer spectroscopies. An X-ray diffraction analysis has been carried out on SnBuⁿ₂Cl₂(dppoet)(1) and SnPrⁿ₂Cl₂(dppoet)(2). Both compounds crystallize in the monoclinic system with a= 13.76(1), b= 15.29(1), c= 18.36(1)Å, β= 113.70(9)°, Z= 4, and space group P2₁/c for (1) and a= 11.362(4), b= 16.816(4), c= 9.324(3)Å, β= 108.94(3)°, Z= 2, and space group P2₁, for (2). The structures have been determined using diffractometer data and refined to conventional R factors of 0.0979 for (1) and 0.0532 for (2)(3 113 and 2 233 reflections, respectively). The major difference between the two structures is associated with behaviour of the dppoet ligand, i.e. symmetrically bidentate in (1) and predominantly unidentate in (2). Tin-119 Mössbauer spectra have been recorded for both (1) and (2) in the temperature range 77–150 K. Quadrupole splitting values of ca. 4 mm s^–1 are in accord with the trans-SnR₂X₄ geometry deduced from the X-ray studies, whilst the values of the temperature coefficients of the recoil-free fraction are characteristic of molecular lattices, the lower value for (2) being attributed to the more open co-ordination of the tin atom in this complex.