Dioxycarbene complexes derived from reactions of tetrairidium carbonyl clusters with oxirane: X-ray crystal structures of and

Abstract

Some novel cyclic-dioxycarbene derivatives of general formula ▪ (L = P t Bu 3, n = 1 ( 2), PPh 3: n = 1 ( 3), 2 ( 4)) and ▪ (L–L = PPh 2PCH 2PPh 2, n = 1 ( 5), norbornadiene, n = 1 ( 6) and 1,5-cyclooctadiene, n = 1 ( 7), 2 ( 8)) have been obtained by reaction of oxirane ▪ with the tetrairidium cluster derivatives [Ir 4(CO) 11(L)] and [Ir 4(CO) 10(L–L)] in the presence of bromide ion as catalyst. Elemental analysis, IR, and NMR spectra ( 1H, 31P{ 1H}, 13C{ 1H}), and for compounds 2 and 5 also the X-ray crystal structures, were carried out for their characterisation. All the derivatives have 3 edge-bridging CO’s on the basal face of the iridium tetrahedron with non-CO ligands in axial and/or radial positions. For the mixed-ligand cluster compounds, two or three stereoisomers were observed in solution by 1H, 31P and 13C NMR spectroscopies at low temperature. All these clusters are fluxional at room temperature.