SOLID-STATE NMR STUDIES AND CRYSTAL STRUCTURE OF THE LAWESSON-REAGENT

Abstract

Abstract X-ray diffraction of the toluene solvate of the Lawesson reagent, C14H14O2P2S4.C7H3, gives the following crystal data: triclinic, PT (no. 2). a = 6.831 (2), b = 9.393 (3), c = 9.793 (3) A, α = 70.33 (2), β = 83.28 (2). γ = 71.35 (2)°, V = 560.6 A3, Z = 1, and D2 = 1.471 Mg m−3. The bond lengths and angles are very close to those observed in the solvent-free crystals. The toluene molecule is disordered over two positions related by an inversion center. The asymmetric unit consists of half the formula unit. This is consistent with the fact that the solid-state 31P CP MAS NMR spectrum gives one set of principal values of the nuclear magnetic shielding tensor. Similar values were obtained for solvates of other aromatic compounds such as benzene, o-dichlorobenzene, methoxybenzene and p-dimethoxybenzene. A comparison with the data for the solvent-free Lawesson reagent shows that the nuclear shielding depends not only on the molecular structure but can also be influenced by short intermolecular S==S dis...