Digold(I) Thianthrenyl Complexes. Effect of Diphosphine Ligands on Molecular Structures in the Solid State and in Solution.

A series of digold complexes possessing two thianthrenyl ligands, Au(Thi)(PhP(CH) PPh) (Thi: 1-thianthrenyl; : = 1, : = 2, : = 3, : = 4), were prepared and characterized by crystallographic and spectroscopic measurements. X-ray crystallography of complexes and revealed U-shaped structures with short Au-Au distances [3.2171(3) Å and 3.0735(2) Å]. Complex and three of the four structure-determined molecules of complex showed structures without Au-Au contacts. UV-vis spectroscopic measurements of - and TD-DFT calculations of the two conformers of revealed that complexes and in the solution phase contained conformers with Au(I)-Au(I) interactions in a much higher proportion than complexes and . As a result, complexes with diphosphine ligands containing an odd number of methylene groups preferred structures with Au-Au interactions in the solid state and in solution. Oxidation of with 2 equiv of PhICl yielded a mixture of monomeric and dimeric thianthrenes and its dimer ligand elimination and C-C coupling, respectively.