Bulky iminophosphonamines for N-P-N coordination: Synthesis and structural characterization of lithium iminophosphonamides and homoleptic bis-chelates of Co(II), Ni(II) and Cu(II)

Abstract

Two new sterically demanding iminophosphonamine ligands (2,4,6-Me3C6H2NH)P(Ph 2)=N (C6H2-2,4,6-Me3)(1) and (2,6-iPr2C6H3NH)P(Ph2)=N(C6H2-2,4,6-Me3) (2) and their lithium derivatives as tmeda adducts (Li·tmeda)[(2,4,6-Me3C6H2)NP(Ph2)=N(C6H2-2,4,6-Me3)] (3) and (Li·tmeda)[(2,6-iPr2C6H3)NP(Ph2)=N(C6H2-2,4,6-Me3)] (4), respectively are reported here. Compounds 1-4 have been investigated by 1H, 13C and 13 P{1H} NMR spectroscopy. The 7Li NMR for complexes 3 and 4 has also been reported. Utility of the ligands and their lithium derivatives have been shown in the synthesis of bis-homoleptic metal complexes M[Ph2P(NC6H2-2,4,6-Me3)2]2 (M = Co (5), Cu (6) and Ni (7). Metal-bis-silylamide generated in situ was reacted with the ligand (for 5 and 6) or the lithium derivative of the ligand was reacted with the metal chloride (for 7). Molecular structure of compounds 1-7 has been elucidated by single crystal X-ray diffraction analyses. The complexes are formed in good yields and are highly lipophilic in a wide range of solvents.