Lal Bahadur Prasad

Rare intermolecular M⋯H–C anagostic interactions in homoleptic Ni(II)–Pd(II) dithiocarbamate complexes

New functionalized homoleptic dithiocarbamates of the form [M(L)2] (M = Ni(II), L = L1, N-(3-methoxybenzyl)-N-(methylbenzyl)dithiocarbamate (1), L3, N-(3,4,5-trimethoxybenzyl)-N-(3-methylpyridyl)dithiocarbamate (3), L4, N-(4-methoxybenzyl)-N-benzyldithiocarbamate (4); Pd(II), L2, N-(N′-methyl-2-pyrrole)-N-benzyldithiocarbamate (2)) have been synthesized and characterized by microanalysis and their structures have been investigated using X-ray crystallography. All the four structures are centrosymmetric with the metal located in a square plane with minor distortions, Pd(II) greater than Ni(II). The crystal structures of 1 and 2 revealed the existence of unique intermolecular C–H⋯M (Ni, Pd) anagostic interactions between the methylene hydrogen atom on the ligand substituents and the metal centres and these enable the formation of 1-D polymeric chains. Particularly, geometric parameters (Pd⋯H–C = 2.61 A; ∠Pd⋯H–C = 173°) for the C–H⋯Pd interactions in 2 are at the border of anagostic and hydrogen bonding. By contrast, 4 shows interactions between the methylene hydrogen atom and the CS2Ni ring rather than the metal alone, while the interaction in 3 is intermediate between the two aforementioned types. These interactions are not shown in solution as revealed by their 1H NMR studies. DFT calculations have been performed to analyse these rare interactions. 1, 3 and 4 are weakly conducting, σrt = 10−10–10−12 S cm−1, and show semiconductor behaviour in the 313–373 K range.

Influence of ligand environment on the structure and properties of silver(I) dithiocarbamate cluster-based coordination polymers and dimers

Luminescent silver(I) homo- and heteroleptic pyridyl functionalised dithiocarbamate (dtc) complexes of the form, [{Ag(L)}4]∞ (L = N-benzyl-N-methylpyridyldtc (L1) 1, bis-(N-methylpyridyl)dtc (L2) 2) and [Ag(L)PPh3]2 (L = L1 (3), L2 (4)) have been synthesized and characterized by elemental analysis, TGA, spectroscopy (IR, 1H, 13C and 31P NMR and UV-Vis) and X-ray crystallography. Complexes 1 and 2 are isomorphous and have a tetranuclear cluster-based coordination polymeric structure. In these tetranuclear silver(I) cluster subunits the four Ag atoms form a distorted tetrahedron. Complexes 3 and 4 are also isostructural and have centrosymmetric structures in which each Ag atom forms a distorted tetrahedral coordination geometry. All complexes are weakly conducting and exhibit semiconductor behaviour. 1–4 are strongly luminescent in solid phase; a correlation between their structure and luminescent properties has been established.

Semiconducting Properties of Some Newly Synthesized Mixed-Metal, Mixed-Licand Complexes. III

Abstract Heterobimetallic complexes of the type MHg(xant)2(dtc)2 [M = Ni(II) or Zn(II); xant = ethyl xanthate. dtc = diethyl dithiocarbamate]. PdHgCl2(dtc)2 and PhHg(dtc)M(xant)2 [M = Cd(II), Zn(II) or Pb(II)] have been prepared and characterized by elemental analyses, molar conductance, magnetic susceptibility, JR. UV-Visible and 1H NMR spectral studies. The diamagnetic nature and electronic spectral studies suggest a square-planar environment around Ni(II) and Pd(II) in the heterobimetallic complexes. IR bands, together with 1H NMR spectral studies, indicate the bridging/bidentate behaviour of the xant and dtc groups. Solid state electrical conductivities of compacted pellets suggest that all the complexes behave as typical semiconductors as their conductivities were found to increase with an increase in temperature from 308 to 328 K. The band gaps evaluated from the plot of conductivity against reciprocal temperature (0.106–0.3 eV) is indicative of their semiconducting behaviour.

Three new homoleptic nickel(II) 1,1-dithiocarbamate complexes: synthesis, structure, electrical conductivity and DFT study

Abstract Three new homoleptic complexes of nickel having the formula [Ni(L1)2] [L1 = C14H14N1O2S2-, N-(4-methoxybenzyl)(furfuryl)methane dithiocarbamate] (1), [Ni(L2)2] [L2 = C17H18N1O2S2–, N-bis(4-methoxybenzyl)methane dithiocarbamate] (2) and [Ni(L3)2] [L3 = C19H21N1O1S2-, N-(4-isopropylbenzyl)(4-methoxybenzyl)methane dithiocarbamate] (3), have been designed, synthesized, and characterized by elemental analysis, IR, 1H and 13C NMR and UV-visible absorption spectra showing that all complexes having analogous geometry and coordination number. The molecular structure of 2 is confirmed by single-crystal X-ray crystallography, which indicates that +2 charges on the metal ion (Ni2+) are balanced by dithiocarbamate anion. The X-ray analysis for 2 reveals a distorted square planar geometry around Ni2+ ion. Both C – H···S and intermolecular C–H···Ni interactions are the only artifact for the resulting Ni-dithiocarbamate architecture in 2. The electrical conductivity measurement between temperatures range of 303–393 K reflects that all complexes exhibit weak semiconducting behavior. Powder XRD, EDAX, and SEM spectra confirm the formation of NiS as thermal decomposition product in 1–3. The crystalline size of samples 1–3 was found to be 20.31 nm, 20.97 nm, and 20.39 nm, respectively. Graphical Abstract