STRUCTURAL ISOMERS OF [AU(CH2)2PPH2]2BR4 .2. CRYSTAL-STRUCTURES OF CIS CIS-[AU(CH2)2PPH2]2BR4 AND THE CATIONIC A-FRAME [(MU-BR)(AU(CH2)2PPH2)2BR2][IBR2]

Two new structural forms of Au(III) dimers, each derived from the oxid ation of the parent compound [Au(I)(CH2)2PPh2]2, have been characteriz ed crystallographically. [(mu-Br)(Au(CH2)2PPh2)2Br2][IBr2](1) is an A- frame cationic species with a bridging halogen atom. cis/cis-[Au(CH2)2 PPh2]2Br4 (2) is an Au(III) dimer with a cis geometry for both metal c enters. Data for 1: Monoclinic, P2(1)/c (No. 14), a = 9.582(5) angstro m, b = 32.551(9) angstrom, c = 12.634(5) angstrom, beta = 109.91(3)-de grees, V = 3705(2) angstrom3, Z = 4, R = 0.084 for 156 parameters (phe nyl rings refined as fixed hexagons). Data for 2: Monoclinic, P2(1)/c (No. 14), a = 8.068(2) angstrom, b = 16.815(10) angstrom, c = 11.991(4 ) angstrom, beta = 108.96(2)-degrees, V = 1539(1) angstrom3, Z = 2, R = 0.046 for 69 parameters (phenyl rings refined as fixed hexagons). A reaction scheme stressing the role of these new species in the redox c hemistry of the dinuclear gold ylide system is proposed.