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. The X-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 center dot center dot center dot O hydrogen bonds (2.652 angstrom), and in Ni[S2P(OBui)(2)](2) the molecules are associated through C-H center dot center dot center dot S hydrogen bonds (2.948 angstrom). The pyrazole adducts are associated through N-H center dot center dot center dot O bonds and N-H center dot center dot center dot 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 center dot center dot center dot O and N-H center dot center dot center dot S bonds (2.502 and 2.965 angstrom, respectively), whereas Ni[S2P(OBui)(2)(Pz)(2)](2) forms linear chains with N-H center dot center dot center dot S bonds 2.728 angstrom. The dithiophosphato groups behave as isobidentate chelating ligands.