Precursor development, characterisation and evaluation of sublimation enthalpies of novel volatile complexes of nickel

Abstract

The nickel complexes namely bis(2-hydroxyacetophenoato)nickel(II), Ni(ohap) 2 ( 1), bis(2-hydroxyacetophenamine)nickel(II), Ni(ohapim) 2 ( 2) and bis(2-hydroxypropiophenamine)nickel(II), Ni(ohppim) 2 ( 3) were synthesised in a systematic approach for the development of volatile nickel precursors for MOCVD. Upon screening these complexes by dynamic TG in an inert N 2 purge gas environment, only complexes 2 and 3 were found to be completely volatile by 363 and 373 °C, respectively. These two were further characterized by FT-IR, C, H, and N and FAB-mass spectrometry. The molecular masses of the predominant Ni bearing vapour species were found to be 326 and 355 Da for 2 and 3, respectively. The complex 3 was analysed by single crystal XRD, 1H and 13C NMR. The equilibrium vapour pressures ( p e) of the precursors 2 and 3 over the temperature ranges of 486–581 and 443–552 K were determined by a TG-based transpiration technique, yielding values of 130.2 (±7.2) and 113.3 (±7.5) kJ mol −1, respectively, for their standard enthalpies of sublimation ( Δ H sub 0 ).