Outer sphere coordination chemistry: Unusual six-coordinate silver(I) complexes with tri-halide–iridium(III) complexes as ligands

Abstract

Reaction of silver(I) with robust halido complexes of Ir(III) leads to second sphere coordination rather than halide abstraction. Two hexa-coordinated pseudo-octahedral silver(I) complexes [(CH3CN)3IrX3AgX3Ir(NCCH3)3]+ (X=Cl, Br) have been synthesized and structurally characterized as PF6− and SbF6− salts, respectively. The synthesis and crystal structure of the new, mononuclear complex, [IrBr3(NCCH3)3], are also reported along with spectroscopic characterization of [IrX3(NCCH3)3] and the trinuclear silver complexes. The electronic structures are analyzed in the framework of ligand field theory and by comparison with high-level correlated multireference ab initio calculations. The ligand field strength of the heavier halide complexes is found to be significantly less sensitive to outer-sphere complexation as compared to the pronounced outer sphere ligation effects commonly observed for fluoride complexes.