A new bulky iminophosphonamide as an N,N′-chelating ligand: synthesis and structural characterization of heteroleptic group 13 element complexes

Abstract

A sterically demanding iminophosphonamine ligand [(2,6-iPr₂C₆H₃N)P(Ph₂)(NtBu)]H (LH) and its lithium derivative [(2,6-iPr₂C₆H₃N)P(Ph₂)(NtBu)](Li·2THF) (1) were used to prepare complexes of group 13 elements. The reaction of LH with AlH₃·NMe₂Et and AlMe₃ respectively, affords [LAlH₂]₂ (2) and LAlMe₂ (3). The lithium derivative 1 when treated with the MCl₃ compound of group 13 yields [(2,6-iPr₂C₆H₃N)P(Ph₂)(NtBu)]MCl₂ (M = B (4); Al (5); and Ga (6). Compound 3 on reaction with a Lewis acid B(C₆F₅)₃ generates the cationic complex [{(2,6-iPr₂C₆H₃N)P(Ph₂)(NtBu)}AlMe]⁺ [MeB(C₆F₅)₃]⁻ (7) that slowly undergoes rearrangement to yield [(2,6-iPr₂C₆H₃N)P(Ph₂)(NtBu)]AlMe(C₆F₅) (8) and MeB(C₆F₅)₂. Compounds 1–8 were characterized using multinuclear NMR, EI-MS and IR techniques and the solid state structure of 1–6 and 8 was elucidated by single crystal X-ray diffraction analyses.