CRYSTAL STRUCTURE OF DIIODOBIS(O-PHENYLENEBIS(DIMETHYLARSINE))GOLD(3) IODIDE - A DISCRETE 6-COORDINATE CATIONIC COMPLEX OF GOLD(3)

The crystal structure of diiodobis(o-phenylenebis(dimethylarsine))gold(III) iodide, abbreviated as Au(diars)2I2, has been determined from three-dimensional, photographically recorded X-ray data. The compound crystallizes in the monoclinic system with a = 21.6 ± 0.2 Å, b = 8.92 ± 0.04 Å, c = 16.10 ± 0.08 Å, β = 107 ± 1°, Z = 4, and space group C2/c. The structure, refined by leastsquares methods to a final conventional R factor for nonzero data of 0.14, consists of layers of Au(diars)2I2+ cations interspersed with iodide ions. The cations have 1-Ci symmetry and the gold(III) atom is coordinated to two diarsine ligands, approximately in a square plane, with iodine atoms in octahedral positions. The Au-As bond distances are shorter than normal, indicating a degree of iπ bonding. The Au-I distances are longer than normal but nevertheless are indicative of strong interactions between the gold and iodine atoms. The latter atoms are each cushioned on four methyl groups which prevent any closer approach. © 1969, American Chemical Society. All rights reserved.