Transmetalation Reactions Yield New Tetra- and Pentairidium Carbonyl Complexes Containing σ-Bonded Phenyl Rings

The new air-stable σ-phenyl tetrairidium carbonyl salt [Et4N][Ir4(CO)11Ph], 1, has been obtained by transmetalation reactions between [Et4N][Ir4(CO)11Br] and SnPh3OH in 45% yield or SnPh4 in 36% yield. Compound 1 reacts with PPh3 to yield the complex [Et4N][Ir4(CO)11(PPh2C6H4)], 2, which contains an ortho-metalated bridging PPh2C6H4 ligand across an edge of a tetrahedral cluster of four iridium atoms. Compound 2 reacts with Ir(CO)(PPh3)2Cl by halide displacement to yield the two new uncharged pentairidium complexes Ir5(CO)12(Ph)(PPh3), 3, and Ir5(CO)11(PPh3)(PPh2C6H4), 4. Compounds 3 and 4 both contain trigonal-bipyramidal clusters of iridium atoms. Compound 3 contains a σ-phenyl ligand coordinated to one of the apical iridium atoms. Compound 4 contains an ortho-metalated PPh2C6H4 ligand that bridges an apical-equatorial edge of the trigonal-pyramidal cluster of metal atoms. Compound 4 was also obtained from 3 by reaction with PPh3.