A AU-197 MOSSBAUER STUDY OF REACTION-PRODUCTS OF TRIMERIC 1-BENZYL-2-GOLD(I)-IMIDAZOLE LEADING TO AU(I) CARBENE OR AU(I) IMIDAZOLINE COMPLEXES AND TRINUCLEAR AU(III) IMIDAZOLYL DERIVATIVES - X-RAY CRYSTAL-STRUCTURE OF [((MU-1-BENZYLIMIDAZOLATO-N3,C2)AU)3I2]

Reactions of the trinuclear [Au3Rim3] compound (Rim = [mu-1-benzylimidazolato-N3,C2] with several reagents capable of oxidative addition have been investigated by Au-197 Mossbauer 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(III)Au(I)2Rim3I2] 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) angstrom 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) angstrom with the C-Au-N angle 170.5(l.6), and Au-I average distances 2.598(3) angstrom, 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) angstrom] indicate a weak metal-metal interaction.