THE SUPRAMOLECULAR STRUCTURES OF COMPLEX TRI[GOLD(I)]SULFONIUM CATIONS

Tris[(trimethylphosphane)gold(I)]sulfonium tetrafluoroborate (1) has been prepared from the corresponding oxonium salt [(Me(3)P)Au]O-3(+) BF4- and bis(trimethylsilyl) sulfide, (Me(3)Si)(2)S. The analogous triisopropylphosphane and methyldiphenylphosphane complexes (2, 3) have been obtained in a similar way. The products are stable crystalline solids, the structure of which has been determined by X-ray methods. They are composed of independent tetrafluoroborate anions and pyramidal tri(gold)sulfonium cations, which are aggregated to form dimeric units (as in 3) or even strings of dimers (as in 1). It is only in complex 2 that steric effects, originating from the bulky phosphane ligands, prevent the building of supramolecular (supracationic) aggregates. In the independent pyramidal cations of 2 only short intracationic Au Au contacts have been detected. These are complemented by intercationic gold-gold contacts of similar length in the structures of 1 and 3. - In the preparation of complex 1, the species [(Me(3)P)Au]S-4(2+) (BF4-)(2) (4) with hypercoordinate sulfur atoms has also been detected by mass spectroscopy.