Anionic Gold(I) Complexes—Twelve‐ and Ten‐Vertex Monocarba‐ closo ‐borate Anions with Carbon–Gold σ 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 σ 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 Δ H iso =(−75±5) kJ mol −1 (solid state) and Δ H ≠ =(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.