No abstract

The reaction of [( t Bu) 2 Ga(µ-Cl)] 2 with 1 molar equiv of Na(S 2 CNR 2 ) yields the di-tert-butyl gallium dithiocarbamate compounds ( t Bu) 2 Ga(S 2 CNR 2 ), R ) Me (1), Et (3), n Pr (5). The tertbutyl gallium bis(dithiocarbamate) compounds ( t Bu)Ga(S 2 CNR 2 ) 2 , R ) Me (2), Et (4), n Pr (6), are formed as minor products. Separation of ( t Bu) 2 Ga(S 2 CNR 2 ) from ( t Bu)Ga(S 2 CNR 2 ) 2 may be readily accomplished by sublimation of the former. Compounds 1 and 3 are low melting point solids allowing their ready use as liquid precursors for MOCVD. The vaporization enthalpies (∆H v ) have been determined, by thermogravimetric methods, for compounds 1, 3, 5, ( n Bu) 2 Ga(S 2 CNMe 2 ) (7), and ( sec Bu) 2 Ga(S 2 CNMe 2 ) (8), and are dependent on both the identity of the substituents on gallium and the dithiocarbamate ligand. An inverse relationship is observed between the ∆H v and the extent of branching of the gallium alkyl. Compounds 1-6 are air stable, but compounds 7 and 8 decompose in humid air. The molecular structures of compounds 1 and 3 have been determined by X-ray crystallography. Gallium sulfide (GaS) thin films have been grown at 375-425 °C by atmospheric pressure metal-organic chemical vapor deposition (AP-MOCVD) using compound 1. Characterization of the films by wavelength dispersive spectroscopy (WDS) microprobe analysis shows the films to have Ga:S compositions of 1:1 with a low degree of impurities (C < 3%; O < 1%). Gallium-rich films were grown from compound 3 using AP-MOCVD and from compound 1 under reduced pressure. XPS studies of the GaS films additionally show an abundance of N on the surface, which has been confirmed to be present throughout the thin film by SIMS measurements. From X-ray diffraction (XRD) and transmission electron microscopy (TEM), the GaS films were found to be a new distorted hexagonal wurtzite phase (a ) 4.590 Å, c ) 6.195 Å).

No abstract

The reaction of GaBut3 with phenylphosphonic acid results in the formation of the unusual phosphonate bridged dimer, [Buf2Ga(p-O2P(Ph)OGaB~t~}]~, whose molecular structure consists of two four-and two three-coordinate gallium centres; while [Buf2Ga(p-02P(Ph)OGaBuf2}]2 exists as the trans isomer in the solid state, it undergoes a trans to cis isomerization in solution, AH = 7 * 1 kJ mol-1 and AS = 25 * 4 J mol-1 K-1.