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

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Abstract
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.