Nickel(ii) complexes of heterodichalcogenido and monochalcogenido imidodiphosphinate ligands: AACVD synthesis of nickel ditelluride

Abstract

The reaction of two equivalents of (TMEDA)Li[(EPⁱPr₂)(TePⁱPr₂)N] (E = S, Se) with NiBr₂(DME) in THF at 23 °C yields homoleptic complexes of heterodichalcogenido PNP ligands Ni[(EPⁱPr₂)(TePⁱPr₂)N]₂ (2, E = S; 3, E = Se). Similarly, the complexes Ni[(PⁱPr₂)(EPⁱPr₂)N]₂ (4, E = Se; 5, E =Te) are obtained by in situ deprotonation of the neutral monochalcogenides EPⁱPr₂NP(H)ⁱPr₂ (E = Se, Te) with ⁿBuLi in THF at −78 °C followed by addition of NiBr₂(DME). The complexes 2–5 have been characterised by multinuclear (¹H, ³¹P, ⁷⁷Se and ¹²⁵Te) NMR spectroscopy in solution and by X-ray crystallography in the solid state, the results of which show that they all exist as the square planar, trans isomers. Aerosol-assisted chemical vapour deposition (AACVD) of Ni[(SePⁱPr₂)(TePⁱPr₂)N]₂ yields crystalline Ni_0.51Te films at 450–500 °C, which were analysed by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and X-ray photoelectron spectroscopy (XPS).