Synthesis and spectral studies of Ni(II) heterocyclic dithiocarbamates with S₂PN chromophore: X-ray crystal structures of bis(1,2,3,4-tetrahydroquinolinecarbodithioato- S,S′)nickel(II) and 1,2,3,4-tetrahydroquinolinecarbodithioato-S,S′)(thiocyanato-N)(triphenylphosphine)nickel(II)

Abstract

Ni(thqdtc) 2 ] (1), [Ni(thiqdtc) 2 ] (2), [Ni(thqdtc)(NCS)(PPh 3 )] (3) and [Ni(thiqdtc)(NCS)(PPh 3 )](4) (where thqdtc = 1, 2, 3, 4-tetrahydroquinolinedithiocarbamate and thiqdtc = 1, 2, 3, 4-tetrahydroisoquinolinedithiocarbamate) have been characterized by electronic, IR and NMR spectroscopy. The structures of 1 and 3 have been determined by single-crystal X-ray crystallography. The ν C−N (thioureide) is higher for 2 and 4 than for 1 and 3 and the upfield shift of the NCS 2 carbon signal for 4 in comparison to 3 is due to the electron-withdrawing resonance effect of the phenyl ring, thereby decreasing the double-bond character in the tetrahydroquinolinedithiocarbamate. On the other hand, the hyper-conjugative electron withdrawal of the benzyl group present in tetrahydroisoquinolinedithiocarbamate is comparatively less significant than its resonance effect. The N 13 CS 2 carbon signal for 3 is observed at 205.0 ppm with an upfield shift of about 3.7 ppm compared with that found in 1 (208.7 ppm). The observed shielding in 3 indicates the effect of PPh 3 on the mesomeric drift of electron density toward nickel through the thioureide C−N bond. Single-crystal X-ray analysis of 1 and 3 showed that the nickel is in a distorted square planar environment with the NiS 4 and NiS 2 PN chromophores, respectively. A significant asymmetry in the Ni−S bonds is observed in 3 [2.2068(5) and 2.1648(5) Å], whereas in compound 1 the bond distances are similar [2.1041(6) and 2.1968 (5) Å]. The observed difference in Ni−S distance in 3 is attributed to the difference in the trans-influencing properties of PPh 3 and NCS − .

Supramolecular architecture of sodium heterocyclic dithiocarbamate salt: Insights from spectral analysis and bond valence sum characterization

“…Tetrahydroquinoline dithiocarbamate complexes would generally involve the coordination of the dithiocarbamate ligands to the metal ions (zinc, nickel, or iron, see Fig. 6 ) [ [25] , [26] , [27] ]. The dithiocarbamate ligands coordinate in a bidentate manner through the sulfur atoms, forming chelate complexes.…”

(1,2,3,4-Tetrahydroisoquinoline-2-carbodithioato-κ2S,S′)(thiocyanato-κN)(triphenylphosphane)nickel(II)

“…Nickel(II) dithiocarbamates can react with Lewis bases such as phosphines as well as hard bases such as nitrogenous ligands, see: Srinivasan et al (2009); Travnicek et al (2008). For the preparation of the title compound, see: Valarmathi et al (2011).…”

“…Compound (I) was prepared according to the literature procedure (Valarmathi et al, 2011). Single crystals of (I) were obtained by slow evaporation of dichloromethane and ethanol (2:1) solution of (I) at room temperature.…”