P. Valarmathi

Synthesis and spectral studies on nitrogen donor adducts of bis(4-ethylpiperazinecarbodithioato-S,S′)M(II) (M = Zn, Cd) and use of adducts of cadmium dithiocarbamate for the preparation of cadmium sulfide

[M(4-epzdtc)2(py)], [M(4-epzdtc)2(1,10-phen)], and [M(4-epzdtc)2(2,2′-bipy)] (where M = Zn(II), Cd(II); 4-epzdtc− = 4-ethylpiperazinecarbodithioate) were synthesized and characterized by IR and NMR (1H, 13C, HSQC and HMBC) spectra. A single-crystal X-ray analysis was carried out for [Zn(4-epzdtc)2(py)]. The N13CS2 chemical shifts of [M(4-epzdtc)2] and its adducts follow the order: [M(4-epzdtc)2] (ca 202 ppm) < [M(4-epzdtc)2(py)] (ca 204 ppm) < [M(4-epzdtc)2(N,N)] (N,N = 1,10-phen, 2,2′-bipy) (ca 206 ppm), due to the change in coordination number. Single-crystal X-ray structural analysis of [Zn(4-epzdtc)2(py)] showed that zinc is five-coordinate with four sulfurs from dithiocarbamate and one nitrogen from pyridine. This complex adopts a geometry intermediate between the tetragonal pyramid (C4v) and trigonal bipyramid (D3h). [Cd(4-epzdtc)2] and its adducts were used as single source precursors for preparation of CdS. The as-prepared CdS was characterized by powder X-ray diffraction, UV-Vis absorption, and fluorescence spectroscopy. The UV-Vis absorption spectra of CdS particles indicate a blue shift in the absorption spectra due to the quantum size effect.

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)

[Ni(thqdtc)2] (1), [Ni(thiqdtc)2] (2), [Ni(thqdtc)(NCS)(PPh3)] (3) and [Ni(thiqdtc)(NCS)(PPh3)] (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 νC−N (thioureide) is higher for 2 and 4 than for 1 and 3 and the upfield shift of the NCS2 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 NCS2 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 PPh3 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 NiS4 and NiS2PN 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 PPh3 and NCS−.

Bis(μ-N-benzyl-N-furfuryldithio-carbamato)-1:2κS,S':S';2:1κS,S':S'-bis-[(N-benzyl-N-furfuryldithio-carbamato-κS,S')cadmium].

In the centrosymmetric title compound, [Cd2(C13H12NOS2)4], pairs of dithiocarbamate ligands exhibit different structural functions. Each of the terminal ligands is bidentately coordinated to one CdII atom and forms a planar four-membered CS2Cd chelate ring, whereas pairs of the tridentate bridging ligands link two neighbouring CdII atoms, forming extended eight-membered C2S4Cd2 tricyclic units whose geometry can be approximated by a chair conformation. The coordination polyhedron of the CdII atoms is a distorted square-pyramid. The five-membered furan ring and the benzene ring are disordered over two sets of sites with an occupancy ratio of 0.62 (8):0.38 (8).

Effect of N-Bound Organic Moiety in Dithiocarbamate (R2NCS−2) and trans Influence of Triphenylphosphine on NiS2PN Chromophore

GRAPHICAL ABSTRACT Abstract Three square planar Ni(II) complexes of the composition [Ni(bzcprdtc)2](1), [Ni(bzcprdtc)(NCS)(PPh3)](2) and [Ni(bzcprdtc)(PPh3)2]ClO4 (3)[(where bzcprdtc = N-benzyl-N-cyclopropyl-dithiocarbamate)] have been synthesized and characterized by 1H and 13C NMR, UV-Vis and FT-IR spectroscopy. 13C NMR spectra show interesting differences between the N13CS2 carbon signals of the parent complex 1 and heteroleptic complex 2. The N13CS2 carbon signal for 2 is observed at 209.3 ppm with an upfield shift of about 3.5 ppm compared with that found for 1 (212.8 ppm). The observed shielding in 2 indicates the effect of PPh3 on the mesomeric drift of electron density toward nickel through the thioureide C‒N bond of [Ni(dtc)(NCS)(PPh3)]. Single crystal X-ray analysis of 2 and [Ni(dbpdtc)(NCS)(PPh3)](4) (dbpdtc = benzyl(4-(benzylamino)phenyl)dithiocarbamate) confirmed distorted square planar arrangement in the vicinity of the nickel atom with a S2NP donor set. Comparative analysis of bond parameters of [Ni(dtc)2] and [Ni(dtc)(NCS)(PPh3)] has also been studied.

cis-Bis(4-methyl-piperazine-1-carbo-dithio-ato-κS,S')bis-(pyridine-κN)cadmium.

In the title complex, [Cd(C6H11N2S2)2(C5H5N)2], the CdII ion is hexacoordinated by two N atoms from two pyridine ligands and by four S atoms from two dithiocarbamate ligands in a distorted octahedral geometry. The CdII ion lies on a twofold axis. The piperazine ring is in chair conformation and its least-squares plane makes a dihedral angle of 81.4 (1)° with that of the pyridine ring.

Trans effect of triphenylphosphine on Ni–S bonds in solid state and DFT/B3LYP optimized structure: Synthesis, spectral and structural studies on (bis(2-ethylhexyl)dithiocarbamato-S,S′)(thiocyanato-N)(triphenylphosphine)nickel(II)

GRAPHICAL ABSTRACT ABSTRACT The compounds [Ni(behdtc)2] (1) and [Ni(behdtc)(NCS)(PPh3)] (2) (where behdtc = bis(2-ethylhexyl)dithiocarbamate) were synthesized and characterized by elemental analyses, electronic, IR, and NMR (1H and 13C) spectroscopy. UV-vis spectral data are consistent with the formation of square-planar nickel complexes. The N13CS2 carbon signal for [Ni(behdtc)(NCS)(PPh3)] is observed at 204.4 ppm with an upfield shift of about 3.8 ppm compared with that found in [Ni(behdtc)2] (208.2 ppm). The observed shielding in [Ni(behdtc)(NCS)(PPh3)] indicates the effect of PPh3 on the mesomeric drift of electron density toward nickel through the thioureide C-N bond. This observation is supported by the higher νC-N values observed in the IR spectrum of the complex 2. A single crystal X-ray analysis of complex 2 proved four coordinated nickel in a distorted square-planar arrangement with a S2NP donor set. A significant asymmetry in the Ni–S bond in 2 (2.1690(10) and 2.2234(10)Å) supports the less effective trans effect of SCN− over PPh3. Molecular electrostatic potential surface map shows that there are no possible sites for nucleophilic attack and S atom of thiocyanate is preferred possible site for electrophilic attack.

(1,2,3,4-Tetra­hydro­isoquinoline-2-carbo­dithio­ato-κ2 S,S′)(thio­cyanato-κN)(tri­phenyl­phosphane)nickel(II)

The NiII atom in the mononuclear title compound, [Ni(C10H10NS2)(NCS)(C18H15P)], exists within a S2PN donor set that defines a distorted square-planar geometry. A significant asymmetry in the Ni—S bond lengths support the less effective trans effect of SCN− over PPh3.