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

The reaction of two equivalents of (TMEDA) Li[((EPPr2)-Pr-i)((TePPr2)-Pr-i)N] (E = S, Se) with NiBr2(DME) in THF at 23 degrees C yields homoleptic complexes of heterodichalcogenido PNP ligands Ni[((EPPr2)-Pr-i)((TePPr2)-Pr-i)N](2) (2, E = S; 3, E = Se). Similarly, the complexes Ni[((PPr2)-Pr-i)((EPPr2)-Pr-i)N](2) (4, E = Se; 5, E = Te) are obtained by in situ deprotonation of the neutral monochalcogenides E=(PPr2NP)-Pr-i(H)Pr-i(2) (E = Se, Te) with (BuLi)-Bu-n in THF at -78 degrees C followed by addition of NiBr2(DME). The complexes 2-5 have been characterised by multinuclear (H-1, P-31, Se-77 and Te-125) 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[((SePPr2)-Pr-i)((TePPr2)-Pr-i)N](2) yields crystalline Ni0.51Te films at 450-500 degrees 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).