POLYNUCLEAR GOLD COMPLEXES OF THE CARBODIIMIDE UNIT [N=C=N](2-)

The reaction of N,N'-bis(trimethylsilyl)carbodiimide with equimolar qu antities of tris[(triphenylphosphine)gold]oxonium tetrafluoroborate in dichloromethane at -40 degrees C gives high yields of a trinuclear co mplex {[(Ph(3)P)Au]2NCN[Au(PPh(2))]}(+) BF4-(1). According to variable temperature NMR data the cation is fluxional in solution with a rapid site exchange of the [(Ph(3)P)Au] units, but has an unsymmetrical (N, N,N') low temperature ground state configuration. A single crystal X-r ay diffraction study has shown that in the crystal lattice these catio ns are associated further into cyclic, hexanuclear dimers through two short head-to-tail Au-Au contacts (auriophilicity). Treatment of compl ex 1 with one equivalent of [(Ph(3)P)Au](+) BF4- in tetrahydrofuran af fords a tetranuclear complex {[(Ph(3)P)Au]2NCN[Au(PPh(3))](2)}(2+) 2BF (4)(-) (2) The ambient temperature NMR spectra of 2 suggest a fluxiona l, pseudo-symmetrical structure, but at low temperature a set of three P-31 signals (1:2:3 intensity) indicates an aggregation into higher n uclearity species with non-equivalent [Au(PPh(3))] units.