The Dynamic Behaviour and NMR Solution structures of complexes of the type (Bisphosphine)(cycloocta-1,5-diene)iridium(I) and the X-ray crystal structure of (cycloocta-1,5-diene)((−)-norphos)iridium(I) hexafluorophosphate

A square-planar coordination geometry was found for the complex [Ir(cod){(?)-norphos}][PF₆] ( 1b [PF₆]; cod = cylcoocta-1,5-diene and (?)-norphos = [(2R,3R)-8-9-10-trinorborn-5-ene-2,3-diyl]bis(diphenylphosphine)) in the solid state by X-ray diffraction. Crystal data: monoclinic, space group P2₁, a = 10.751 (6), b = 18.669(14), c = 12.037(8) Å, β = 114.82(5)°, Z = 2. A total structural assignment including the configurational and conformational aspects of this and the related compounds [Ir(bishosphine)(cod)]X (bisphosphine = (?)-chiraphos = (2S,3S)-2,3-bis(diphenylphosphino)butane and (?)-norphos, X = Cl, CF₃SO₃, or PF₆) was carried out in solution by one- and two-dimensional NMR spectroscopy. The complexes containing the CF₃SO₃^? and PF₆^? anions are four-coordinate cations with square-planar geometry, whereas the chlorides are five-coordinate neutral compounds showing solvent-dependent dynamic behaviour. In toluene, two diastereoisomers of [IrCl(cod){(?)-norphos}] ( 2b ) exist and interconvert slowly at room temperature. This interchange is fast in CDCl₃ solution, and it is likely to involve Cl dissociation and the formation of the cation [Ir(cod){(?)-norphos}]⁺ as an intermediate.