X-ray structure and fluxional behaviour of N,N′-di-p-fluorophenyltriazenido complex of nickel(II)

The Ni(II) triazenide complex, trans-(o-Tol)Ni(PEt3)2N3Ar2 (Ar=p-FC6H4) (1), was synthesized by the reaction of trans-(o-Tol)Ni(PEt3)2Br with Ar2N3Na. The crystal structure as well as the 1H-, 19F- and 31P-NMR spectra in toluene-d8 at different temperatures are reported. It was found that the triazenido group acts as a monodentate ligand. Complex 1 in solid state has a S-cis-structure with NiN(3) σ-bond and exists as a 3:1 mixture of two isomers with cisoid or transoid orientation of the Me group of the o-tolyl ligand relative to the N(1)N(2) bond. It was established that the N,N′-migration of (o-Tol)Ni(PEt3)2 group occurs in a solution of 1. The migration rate increases with the temperature increase in the range from −104 to −45°C. However, a further increase in the temperature slows down the process.