Anionic gold(I) complexes-twelve- and ten-vertex monocarba-closo-borate anions with carbon-gold sigma bonds.

The anionic gold(I) complexes 1-(Ph(3)PAu)-closo-1-CB(11)H(11) (1), 1-(Ph(3)PAu)-closo-1-CB(9)H(9) (2), and 2-(Ph(3)PAu)-closo-2-CB(9)H(9) (3) with gold-carbon 2c-2e sigma bonds have been prepared from [AuCl(PPh(3))] and the respective carba-closo-borate dianion. The anions have been isolated as their Cs(+) salts and the corresponding Et(4)N salts were obtained by salt metathesis reactions. The salt Cs-3 isomerizes in the solid state and in solution at elevated temperatures to Cs-2 with DeltaH(iso)=(-75+/-5) kJ mol(-1) (solid state) and DeltaH( not equal)=(118+/-10) kJ mol(-1) (solution). The compounds were characterized by vibrational and multi-NMR spectroscopies, mass spectrometry, elemental analysis, and differential scanning calorimetry. The crystal structures of [Et(4)N]-1, [Et(4)N]-2, and [Et(4)N]-3 were determined. The bonding parameters, NMR chemical shifts, and the isomerization enthalpy of Cs-3 to Cs-2 are compared to theoretical data.