En route to phosphonato iridium(I) complexes: the decisive effect of an intramolecular hydrogen bond

Pentacoordinated iridium(i) complexes of formula IrCl(SiNP)(tfbb) (1) and IrCl(HNP)(tfbb) (2) (SiNP = SiMe{N(4-CHCH)PPh}; HNP = NH(4-CHCH)PPh) have been prepared and fully characterised. Both feature a distorted square pyramidal coordination polyhedron at the metal centre in the solid state and are fluxional in solution. Their reaction with trimethyl phosphite yields the derivatives [Ir(SiNP){P(OMe)}(tfbb)]Cl ([3]Cl) and Ir{PO(OMe)}(HNP)(tfbb) (4). The course of the reaction between IrCl(HNP)(tfbb) (2) and trimethyl phosphite was elucidated by NMR spectroscopy and DFT calculations, showing that the intermediate [Ir(HNP){P(OMe)}(tfbb)] (5) forms and further reacts with the chloride anion yielding the phosphonato derivative 4 and methyl chloride. The decisive role of the N-H group in the formation of the phosphonato ligand has been established by IR and NMR spectroscopic measurements and by DFT calculations.Financial support from Spanish “Ministerio de Economía y Competitividad” (MINECO/FEDER, CTQ2013–42532–P) and “Diputación General de Aragón” (DGA/FSE-E07) is gratefully acknowledged.Peer Reviewe