SILYLIMIDO AND DISILYLAMIDO GROUPS AS CLUSTERING CENTERS FOR (PHOSPHANE)GOLD(I) UNITS - AURATED SILYLAMMONIUM CATIONS

The reaction of hexamethyldisilazane with tris[(phosphane)aurio(I)]oxonium tetrafluoroborates affords the corresponding trinuclear mu(3)-trimethylsilylimido compounds of the type {[(R(3)P)Au](3)NSiMe(3)}(+) BF4- (1a-f). With (triphenylsilyl)amine and the oxonium reagents the analogous series of Ph(3)Si derivatives (2a-f) is formed (R = Me, Et, iPr; R(3) = Ph(2)Me; R = Ph, o-Tol). The Et(3)P-based oxonium salt and (Me(3)Si)(2)NH give the dinuclear mu-trimethylsilylamido complex {[(Et(3)P)Au]N-2(SiMe(3))(2)}(+) BF4- (3) as the main product. The crystal and molecular structures of complexes 2a, 2e, and 3 were determined. The trinuclear cations have a pseudo-tetrahedral structure with small Au-N-Au angles and short Au-Au distances for the SiNAu3 units. The Ph(3)SiN units in 2a and 2e are capping triangles of gold atoms, while in the cation of 3 the (Me(3)Si)(2)N unit is bridging a pair of gold atoms. In the P-31- and N-14-NMR spectra of compounds 1 and 2 (except for 1f and 2f) the coupling J(P-31,N-14) is, observed. This coupling is temperature-dependent, owing to changes in the relaxation characteristics in solution at low temperature. The decomposition of compounds 1 and 2 leads to the formation of pentanuclear dications {[(R(3)P)Au]N-5}(2+) for R = Me, Ph.