COMPLEXES OF IR-3(CO)(3)(ETA(5)-C9H7)(3) WITH METAL FRAGMENT ELECTROPHILES

The reactions of C-3v Ir-3(mu-CO)(3)(eta(5)-C9H7)(3) (1) with various metal electrophiles yield the cationic tetranuclear clusters [Ir-3{M(P Ph3)}(CO)(3)(eta(5)-C9H7)(3)][PF6] (2, M = Cu; 3, M = Ag; 5, M = Au), [Ir3Tl(mu-CO)(3)(eta(5)-C9H7)(3)][PF6] (4), and [Ir-3(HgR)(CO)(3)(eta( 5)-C9H7)(3)][PF6] (6, R = Ph; 7, R = W(CO)(3)(eta(5)-C5H5)). Compounds 5-7 are best prepared via compound 4. The structures of compounds 4 a nd 5 have been determined by X-ray diffraction. The C-3v symmetry of t he parent cluster 1 is maintained in the structure of 4. The molecule consists of a triangle of iridium atoms, each edge of which has a brid ging carbonyl oriented out of the plane in the same direction and each vertex of which has an eta(5)-indenyl ligand oriented toward the oppo site side of the plane. The thallium atom adopts a face-capping mode o f coordination on the same side of the triiridium plane as the three i ndenyl ligands and is encapsulated by the phenylene portions of the in denyl groups. The molecular structure of 5 consists of a AuIr3 butterf ly framework with a hinge angle of 153.63(3)degrees and the gold atom in a wingtip position. Each CO ligand is bonded in a terminal mode to one iridium center, with one CO ligand 'down' relative to the Ir-3 pla ne and two CO ligands 'up', flanking the Ir-Ir edge bridged by the Au( PPh3)(+) fragment. The indenyl ligands take up positions opposite thos e of the CO ligands at each iridium center. The infrared and H-1 NMR s pectra of compounds 2, 3, 5, 6, and 7 are all very similar and are ful ly consistent with the solid-state structure of 5.