A dynamic NMR study of sulphur inversion in transition metal complexes of 2,6-dithiaspiro[3.3]heptane (2,6-DTSH), 2,6-DTSH-2-oxide and 2,6-DTSH-2,2-dioxide

Article abstract of DOI:10.1016/S0277-5387(98)00445-8

The following complexes were synthesised [W(CO)₅L¹], [{W(CO)₅}₂L¹], [W(CO)₅L²], [W(CO)₅L³], [{PdCl₂(PPh₃)}₂L¹], [PdCl₂(PPh₃)L²] and [PdCl₂(PPh₃)L³] where L¹=2,6-dithiaspiro[3.3]heptane (2,6-DTSH), L²=2,6-DTSH-2-oxide and L³=2,6-DTSH-2,2′-dioxide. In solution these complexes exhibit pyramidal inversion of the metal-coordinated sulphur atom(s), rates and activation energies of which were evaluated by total NMR bandshape analysis. ΔG^? values were in the range 45-50 kJ mol^-1. These magnitudes are discussed in terms of ring geometry distortions and sulphur lone pair interactions.