Transition metal coordination compounds with the dithiooxalate ligand. Synthesis,spectroscopic studies,crystal structure,and bonding of (C5H5NH)2[Ni(S2C2O2)2]

Several new compounds belonging to the family of bis(dithiooxalato)-nickelate(II) complex anion with the general formula (BH)₂Ni(S₂C₂O₂)₂], where B=pyridine, 3-methylpyridine, 3-ethylpyridine, 4-methylpyridine, and 4-ethylpyridine (hereafter abbreviated as PYNIDT, M3NIDT, E3NIDT, M4NIDT, and E4NIDT, respectively) have been prepared. PYNIDT, M3NIDT, and E3NIDT are isostructural between them and different from the two other compounds, M4NIDT and E4NIDT, which are also isostructural. All of these compounds crystallize in the monoclinic system, space groupP2₁/n withZ=2. Crystal parameters for PYNIDT are:a=5.793(3),b=14.280(5),c=11.222(3) Å,=97.29(4)°,V=920.8(9) ų,F(000)=468,D _x =1.66,D _o=1.65(1) Mg m^–3,R=0.048, andR _w =0.057 for 1236 observed reflections. The IR and UV-V spectra show that the organic bases are protonated and the anion presents the well-known spectrum for the bis(dithiooxalato)-nickelate(II) anions. Thermogravimetric studies indicate that the compounds are anhydrous. The structure solution of PYNIDT confirms that this compound contains discrete quasi-planar complex Ni(S₂C₂O₂)₂]^2– anions and (C₅H₅NH)⁺ planar cations linked through hydrogen bonds. The structure stacks into layers where the ions are associated into cationanioncation entities through bifurcated hydrogen bonds.