Hydrogen bond supramolecular self-assembly in nickel(II) dithiophosphates, Ni[S2P(OR)2]2, R = sec-Bu, iso-Bu, and their bis(pyrazole) adducts

The reaction between nickel(II) nitrate and potassium phosphorus-1,1-dithiolates (di-sec-butyl and di-iso-butyl) in methanol yields 2:1 complexes which were characterized by FT-IR and NMR spectroscopy. 2:1 pyrazole adducts of both compounds were also obtained. ray diffraction analysis of the compounds reveals square planar, four-coordination geometry for the homoleptic compounds and a six-coordinated distorted octahedral geometry for the adducts. In Ni[S2P(OBus)2]2 the molecules are associated through C–H⋯O hydrogen bonds (2.652 Å), and in Ni[S2P(OBui)2]2 the molecules are associated through C–H⋯S hydrogen bonds (2.948 Å). The pyrazole adducts are associated through N–H⋯O bonds and N–H⋯S bonds from the pyrazole nitrogen atoms, to form supramolecular assemblies. Thus, Ni[S2P(OBus)2(Pz)2]2 (Pz = pyrazole) forms bi-dimensional layers through N–H⋯O and N–H⋯S bonds (2.502 and 2.965 Å, respectively), whereas Ni[S2P(OBui)2(Pz)2]2 forms linear chains with N–H⋯S bonds 2.728 Å. The dithiophosphato groups behave as isobidentate chelating ligands.