Contrasting a series of bidentate amido phosphine oxide, sulfide, or selenide ligands and complexes of dimethyl aluminum and indium

Abstract

A series of EP(V)-imine phosphine-imine ligands (Dipp-NC(CH₃)-(CH₂)-PE(Ph₂)) (Dipp = 2,6-diisopropylphenyl, E = O, S, Se) and corresponding dimethyl aluminum and indium complexes were prepared and characterized using multi-nuclear NMR spectroscopy and SC-XRD. Solution-state ¹H and ³¹P NMR spectroscopy indicate a mixture of isomers in solution (C₆D₆, CDCl₃, and CD₃CN). Solid state structures of both the imine and (E)-enamine isomers of the oxygen-based ligand have been observed. These three ligands (L) were then deprotonated with M(CH₃)₃ (M = Al or In), with methane loss forming a 6-membered ring via bidentate chelation ((κ²-L)M(CH₃)₂). The indium/oxide complex also crystallized as a 12-membered ring.