Complexes of Ir3(CO)3(η5-C9H7)3with Metal Fragment Electrophiles

Abstract

The reactions of C3v Ir3(μ-CO)3(η5-C9H7)3 (1) with various metal electrophiles yield the cationic tetranuclear clusters [Ir3{M(PPh3)}(CO)3(η5-C9H7)3][PF6] (2, M = Cu; 3, M = Ag; 5, M = Au), [Ir3Tl(μ-CO)3(η5-C9H7)3][PF6] (4), and [Ir3(HgR)(CO)3(η5-C9H7)3][PF6] (6, R = Ph; 7, R = W(CO)3(η5-C5H5)). Compounds 5−7 are best prepared via compound 4. The structures of compounds 4 and 5 have been determined by X-ray diffraction. The C3v symmetry of the 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 bridging carbonyl oriented out of the plane in the same direction and each vertex of which has an η5-indenyl ligand oriented toward the opposite side of the plane. The thallium atom adopts a face-capping mode of coordination on the same side of the triiridium plane as the three indenyl ligands and is encapsulated by the phenylene portions of the indenyl groups. The molecular structure of 5 consists of a AuIr3 butterfly framework with a hinge angle of 153.63(3)° 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 Ir3 plane and two CO ligands ‘up', flanking the Ir−Ir edge bridged by the Au(PPh3)+ fragment. The indenyl ligands take up positions opposite those of the CO ligands at each iridium center. The infrared and 1H NMR spectra of compounds 2, 3, 5, 6, and 7 are all very similar and are fully consistent with the solid-state structure of 5.