Spectroscopic study of phosphine selenide complexes of Au(I) and X-ray structure of [(cyclohexyl)(3)PSeAuBr]

The X-ray structure determination of the complex, [(cyclohexyl)(3)PSe-AuBr] , revealed a triclinic space group P-1, with a = 9.7654(7), b = 10.9441(9), c = 11.2064(9) Angstrom, alpha = 117.076(6)degrees, beta = 99.076(6)degree s, gamma = 95.417(6)degrees, V = 1034.07(14) Angstrom (3) and Z = 2. The Au (I) atom in this complex has a linear coordination with Se1 atom at 2.3776( 9) Angstrom on one side and Br1 at 2.3843(9) Angstrom at the trans position making the Se1-Au1-Br1 angle of 177.97(4)degrees. The P1 atom in the phosp hine has tetrahedral geometry. All three cyclohexyl groups are in their usu al boat conformation. The phosphorus atom of the triphenylphosphine is appr oximately perpendicular to the Sel-Aul-Brl linkage with P1-Se1-Au1 angle of 99.19(6)degrees. The Delta delta in the(31)P NMR of the free ligands and t heir corresponding L-Se-Au-Br (L-Se = trialkyl/arylphosphine selenides) com plexes, and the changes in the P-Se bond frequencies in the FTIR upon compl exation, are indicative of the bonding of the ligand to Au(l) through selen ium. There is a strong corelation between the chemical shifts of the P-31 N MR and the C-P-C angle in the phosphines.