The first Au carbene complex was prepared by reacting a geminal dianion with a (P,C) cyclometalated Au precursor. Its structure and bonding situation have been thoroughly investigated by experimental and computational means. The presence of a high-energy highest occupied molecular orbital (HOMO) centered at the carbene center suggests nucleophilic character for the Au carbene complex. This unprecedented feature was confirmed by reactions with two electrophiles (PhNCS and CS ), resulting in two types of C=C coupling reactions.

The reaction of the geminal dianion (SCS)2– 1 with 2 equiv of BH3·SMe2 leads to the isolation and full characterization of the new organoborane [(SCS)­BH2]­[Li­(THF)2] 2, in which the CB bond possesses ambiphilic, multiple character. Treatment of 2 with another 1 equiv of BH3·SMe2 allows the isolation of the rare cyclic diborane species [(SCS)­B2H5]­[Li­(OEt2)] 4. The electronic structures of both compounds were investigated by means of DFT calculations. Compound 4 is an efficient catalyst for the reduction of CO2 to methanol derivatives by BH3·SMe2. A TON of ca. 2800 (TOF = 127 h–1) was achieved using 0.1 mol % of 4 in THF.