A Au mössbauer study of reaction products of trimeric 1-benzyl-2-gold(I)-imidazole leading to Au carbene or Au imidazoline complexes and trinuclear Au imidazolyl derivatives. X-Ray crystal structure of [{(μ-1-benzylimidazolato-N,C)Au}3I2]

Reactions of the trinuclear Au₃Rim₃] compound (Rim = μ-1-benzylimidazolato-N³,C²] with several reagents capable of oxidative addition have been investigated by ¹⁹⁷Au Mössbauer spectroscopy. The reaction products are either Au^I carbene mononuclear and binuclear complexes or trinuclear Au^III and mixed-valence compounds. The X-ray crystal structure of the mixed-valence complex Au^IIIAu^I₂Rim₃I₂] has been determined. Two two-coordinate Au^I centres show average Au---C and Au---N distances of 2.02(3) and 2.04(2) Å and average C---Au---N angles of 175.0(1.2)°, whereas the four-coordinate Au^III centre gives Au---C and Au---N 1.96(4) and 1.91(3) Å with the C---Au---N angle 170.5(1.6)°, and Au---I average distances 2.598(3) Å, with an I---Au=I angle 175.8(1)°. The Au---Au intramolecular distances Au(1) Au(2) 3.432(3), Au(1) Au(3) 3.508(3), Au(2) Au(3) 3.464(3) Å] indicate a weak metal-metal interaction.