Dynamic Properties of Methyl(trimethylphosphane)nickel Complexes Containing (2‐Diphenylphosphanyl)phenylamido Ligands

P,N-chelates of nickel NiCl[2-(Ph2P)C6H4NR](PMe3) (1: R = H; 2: R = SiMe3) have been obtained from NiCl2(PMe3)2 and 2-(Ph2P)C6H4NRLi. Reaction with MeLi affords methylnickel compounds NiMe[2-(Ph2P)C6H4NR](PMe3) (3: R = H; 4: R = Me; 5: R = SiMe3). By the same route NiMe[2-(R1R2P)C6H4NR](PMe3) (6: R1 = R2 = CHMe2) was synthesized. Solutions in THF contain cis and trans isomers of square-planar complexes, and dynamic NMR spectroscopy shows dissociation of trimethylphosphane to be more rapid in the trans isomers. In a crystal of 5 the molecular structure is cis-5. Out of these complexes only 3 and 4 add trimethylphosphane to form pentacoordinate compounds NiMe[2-(Ph2P)C6H4NR](PMe3)2 (7, 8) in the crystal as shown by the molecular structure of 7 while in THF equilibria 7 ⇄ cis-1 and 8 ⇄ cis-2 are observed by NMR spectroscopy. The same solution properties are found with NiMe[2-(R1R2P)C6H4NR](PMe3)2 (9: R1 = CMe3, R2 = Ph). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)