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}][PF 6 ] ( 1b [PF 6 ]; cod = cylcoocta‐1,5‐diene and (−)‐norphos = [(2 R ,3 R )‐8‐9‐10‐trinorborn‐5‐ene‐2,3‐diyl]bis(diphenylphosphine)) in the solid state by X‐ray diffraction. Crystal data: monoclinic, space group P 2 1 , 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 = (2 S ,3 S )‐2,3‐bis(diphenylphosphino)butane and (−)‐norphos, X = Cl, CF 3 SO 3 , or PF 6 ) was carried out in solution by one‐ and two‐dimensional NMR spectroscopy. The complexes containing the CF 3 SO 3 − and PF 6 − 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 CDCl 3 solution, and it is likely to involve Cl dissociation and the formation of the cation [Ir(cod){(−)‐norphos}] + as an intermediate.