PUB - Publikationen an der Universität Bielefeld

A series of dinuclear (phosphine)gold(I) complexes of the ambidentate 1,3,4-thiadiazoledithiolate ligand (SSS) were prepared in high yield from the corresponding (phosphine)gold(I) chlorides and K-2(SSS) in methanol. While mononuclear components (R3P)AuCl with R-3 = Ph-3, Ph2Py, or Me-3 (1-3) crave open-chain complexes, the dinuclear components ClAu(Ph2P-E-PPh2)AuCl with E = (CH2)(6), (C5H4)Fe(C5H4), or 1,4-CH2C6H4CH2 afforded cyclic complexes (4-6). The products have been characterized by analytical and spectroscopic methods, and the crystal structures of 1-4 have been determined by single-crystal X-ray techniques. Crystals of 1 [(CH2Cl2)(2)] and 2 (CH2Cl2) contain the molecules aggregated in strings with long and probably very weak intermolecular Au . . .S contacts. The P-Au-S groups are aligned parallel head-to-tail and shifted in opposite directions to reduce steric conflicts, thus ruling out aurophilic Au . . . Au bonding. By contrast, in crystals of 3 (CH2Cl2) with smaller tertiary phosphine ligands, the molecules are aggregated via short [3.0089(3) and 3.1048(5) Angstrom] and probably strong aurophilic bonding to give a two-dimensional network with tetranuclear units formed from four (Me3P)AuS moieties of four different molecules as the connecting elements. In these tetranuclear units [(Me3P)AuS-](4), the P-Au-S axes are rotated against each other ("crossed swords") by 108.5 degrees (P2-Au2 . . . Au2'-P2') or 116.9 degrees (P2-Au2 . . . Au1'-P1'), respectively, to minimize steric conflicts. There is also significant bending of the P-Au-S axes to bring the metal atoms closer together: P1-Au1-S1 = 171.88(8)degrees and P2-Au2-S2 = 165.52(8)degrees. In the crystals of the cyclic complex 4 which contain no solvent molecules, the molecular units are aggregated in strings with short closed-shell interactions between the gold atoms of neighboring molecules [3.1898(3) Angstrom]. Because of the metallocyclic structure, the shielding of the gold atoms is reduced to allow aurophilic bonding as the P-Au-S groups are rotated against each other (crossed) by a dihedral angle P-Au . . . Au-P of 74.6 degrees.