Gallium and Indium β‐Diketonate Complexes: AACVD of [In(thd)₃] and the Attempted Synthesis of Gallium and Indium Bis(β‐diketonates)

Abstract

Abstract Aerosol‐assisted chemical vapour deposition (AACVD) of a suspension of [In(thd) 3 ] (thd = 2,2,6,6‐tetramethylheptane‐3,5‐dionate) in CH 2 Cl 2 at 450 °C afforded thin crystalline films of indium oxide. The films were analyzed by scanning electron microscopy (SEM), glancing angle X‐ray diffraction (XRD) and energy dispersive analysis of X‐rays (EDX). Efforts to grow thicker films were hampered by the poor solubility of [In(thd) 3 ], so the synthesis of heteroleptic compounds of the type [M(bdk) 2 X] (M = Ga, In; bdk = β‐diketonate; X = chloride, hydride, methyl) was attempted such that the solubility could be improved by tuning the ligands surrounding the metal centre. Reaction of stoichiometric amounts of β‐diketones [Hthd and 2,4‐pentanedione (acetylacetone, Hacac)] with Lewis base‐stabilized adducts of GaH 3 resulted only in the isolation of the homoleptic gallium tris(β‐diketonate) compounds [Ga(bdk) 3 ], instead of the expected heteroleptic gallium bis(β‐diketonate) hydride, [GaH(bdk) 2 ]. An unexpected reduction of Hthd to 2,2,6,6‐tetramethylheptane‐3,5‐diol was also observed. Other attempted syntheses of gallium bis(β‐diketonate) compounds also resulted in the isolation of homoleptic [Ga(bdk) 3 ] complexes and similar results were obtained for indium. The compounds were characterised by 1 H NMR spectroscopy, mass spectrometry and elemental analysis and the structures of [In(thd) 3 ] and 2,2,6,6‐tetramethylheptane‐3,5‐diol were determined by X‐ray crystallography.