Schiff Base Of S-methyldithiocarbazate Research Articles

Synthesis, characterization, thermal and DFT studies of S-methyl-β-N-(3-(2-nitrophenyl)allylidene)dithiocarbazate as anti-bacterial agent

S-Methyl-β-N-(3-(2-nitrophenyl)allylidene)dithiocarbazate (HL), Schiff base of S-methyl dithiocarbazate, was synthesized by 1:1 condensation between S-methyl dithiocarbazate and trans-o-nitro cinnamaldehyde. It's in-vitro cytotoxicity is assayed against two habitually infection causing bacteria strains including gram-positive Staphylococcus aureus and gram-negative Escherichia coli for antibacterial activity. The results showed appreciable biological activity and the activity increased with increase in concentration. This nitrogen-sulfur based Schiff base (HL) was characterized by Mass, FT-IR, 1H-NMR, 13C NMR, Raman, and UV–Vis spectroscopic techniques. Theoretical quantum chemical calculation has been performed using DFT in combination with B3LYP exchange correlation functional and 6–311++ G (d, p) basis sets level. The computed parameters were: Chemical potential of compound (μ) −0.174 eV, HOMO-LUMO energy gap −0.11093 eV, chemical hardness (ɳ) −0.055 eV, softness (S) 2.164 eV, ionization energy (IE) −0.23026 eV, electron affinity (EA) −0.11933eV, the electronegativity (EN) 0.174 eV, dipole moment (D) 1.3383 Debye and relative stabilization energy −1536.982 eV. In the theoretical FT-IR spectrum analysis 81 fundamental vibrational modes has be observed because of non-linear structure of HL, with potential energy distribution percentage (PED%) by using VEDA-4 package. Theoretically calculated parameters like 1H-NMR, 13C NMR, FT-IR, UV-VIS, Raman, electrostatic potential and HOMO-LUMO energy gap were in conformity with experimental results. Thermal reactivity of the ligand was studied by TGA decomposes completely to give gaseous products.

Dimeric nickel(II) and copper(II) complexes of the pentadentate N3S2 chelating agents derived from S-alkyl/aryl esters of dithiocarbazic acid

The helical dimeric copper(II) complex, [Cu(dapsbz)]2 (dapsbz=doubly deprotonated form of the 2,6-diacetylpyridine Schiff base of S-benzyldithiocarbazate) has been synthesized and structurally characterized. Each Schiff base in the dimer acts as a doubly negatively charged N3S2 pentadentate chelating agent, providing three donor atoms, viz. the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom, to one copper ion and the azomethine nitrogen atom and thiolate sulfur atom to the second copper(II) ion. The stereochemistry adopted by each copper(II) ion in the dimer is five-coordinate, approximately square-pyramidal, with a CuN3S2 coordination core. In the dimeric nickel(II) complex, [Ni(dapsme)]2 (dapsme=doubly deprotonated form of the 2,6-diacetylpyridine Schiff base of S-methyldithiocarbazate), the Schiff base also coordinates with the two nickel(II) ions as pentadentate N3S2 chelating agent, but here the pyridine nitrogen atom of each ligand acts as a bridging donor atom. The azomethine nitrogen and thiolate sulfur atoms of one arm of a ligand coordinate with one nickel ion whereas the azomethine nitrogen and thiolate sulfur atoms of the other arm of the same ligand coordinate with a second nickel atom, the stereochemistry adopted by each nickel atom in the dimer being distorted octahedral with a NiN4S2 coordination sphere.

The Preparation, Characterization and Biological Activity of Palladium(II) and Platinum(II) Complexes of Tridentate NNS Ligands Derived from S-methyl- and S-benzyldithiocarbazates and the X-ray Crystal Structure of the [Pd(mpasme)Cl] Complex

New complexes of general formula, [M(NNS)Cl] (M = PdII, PtII; NNS = anionic forms of the 6-methyl-2-formylpyridine Schiff bases of S-methyl- and S-benzyldithiocarbazates) have been prepared and characterized by a variety of physico-chemical techniques. Based on conductance and spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(mpasme)Cl] complex (mpasme=anionic form of the 6-methyl-2-formylpyridine Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted square-planar geometry with the ligand coordinated to the palladium(II) ion via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom; the fourth coordination position around the palladium(II) ion is occupied by the chloride ligand. The distortion from a regular square-planar geometry is ascribed to the restricted bite angle of the ligand. Both the Schiff bases exhibit strong cytotoxicity against the human ovarian cancer (Caov-3) cell lines, the S-methyl derivative being two times more active than the S-benzyl derivative. The [Pt(mpasme)Cl] complex is moderately active but the palladium(II) complex is weakly active against this cancer. None of the complexes of Hmpsbz are active against Caov-3. The Schiff base, Hmpasme exhibits moderate activity against the bacteria, MRSA, P. aeruginosa and S. typhimurium but is inactive against B. subtilis. Coordination of the ligand with palladium(II) substantially reduces its activity. The Schiff base, Hmpasbz and its palladium(II) and platinum(II) complexes are inactive against these bacteria. The Schiff bases and their palladium(II) and platinum (II) complexes are inactive against the pathogenic fungi, C. albican, Aspergillus ochraceous and Saccharomyces cerevisiae.

Synthetic, EPR spectroscopic, magnetic and X-ray crystallographic structural studies on copper(II) complexes of the tridentate N 2S donor ligand formed from 6-methyl-2-formylpyridine and S-methyldithiocarbazate (Hmpsme)

New copper(II) complexes of general empirical formula, Cu(mpsme)X · xCH 3COCH 3 (mpsme = anionic form of the 6-methyl-2-formylpyridine Schiff base of S-methyldithiocarbazate; X = Cl, N 3, NCS, NO 3; x = 0, 0.5) have been synthesized and characterized by IR, electronic, EPR and susceptibility measurements. Room temperature μ eff values for the complexes are in the range 1.75–2.1 μ B typical of uncoupled or weakly coupled Cu(II) centres. The EPR spectra of the [Cu(mpsme)X] (X = Cl, N 3, NO 3, NCS) complexes reveal a tetragonally distorted coordination sphere around the mononuclear Cu(II) centre. We have exploited second derivative EPR spectra in conjunction with Fourier filtering (sine bell and Hamming functions) to extract all of the nitrogen hyperfine coupling matrices. While the X-ray crystallography of [Cu(mpsme)NCS] reveals a linear polymer in which the thiocyanate anion bridges the two copper(II) ions, the EPR spectra in solution are typical of a magnetically isolated monomeric Cu(II) centres indicating dissociation of the polymeric chain in solution. The structures of the free ligand, Hmpsme and the {[Cu(mpsme)NO 3] · 0.5CH 3COCH 3} 2 and [Cu(mpsme)NCS] n complexes have been determined by X-ray diffraction. The {[Cu(mpsme)NO 3] 0.5CH 3COCH 3} 2 complex is a centrosymmetric dimer in which each copper atom adopts a five-coordinate distorted square-pyramidal geometry with an N 2OS 2 coordination environment, the Schiff base coordinating as a uninegatively charged tridentate ligand chelating through the pyridine and azomethine nitrogen atoms and the thiolate, an oxygen atom of a unidentate nitrato ligand and a bridging sulfur atom from the second ligand completing the coordination sphere. The [Cu(mpsme)(NCS)] n complex has a novel staircase-like one dimensional polymeric structure in which the NCS − ligands bridge two adjacent copper(II) ions asymmetrically in an end-to-end fashion providing its nitrogen atom to one copper and the sulfur atom to the other.

Synthesis, characterization and X-ray crystal structures of the bis?ligand zinc(II) and cadmium(II) complexes of the methylpyruvate Schiff base of S-methyldithiocarbazate

New bis-chelated ZnII and CdII complexes of empirical formula, [M(mpsme)2] (mpsme=the anionic form of the tridentate ONS donor ligand formed from methylpyruvate and S-methyldithiocarbazate) have been prepared and characterized by conductance, i.r., electronic and n.m.r. spectroscopic techniques. Spectral evidence supports a six-coordinate distorted octahedral structure for these complexes. X-ray crystallographic structural analysis also confirms that, in both the [Zn(mpsme)2] and [Cd(mpsme)2] complexes, the methylpyruvate Schiff base of S-methyldithiocarbazate is coordinated to the metal ions as a uninegatively charged tridentate ONS chelating agent via the carbonyl oxygen atom, the azomethine nitrogen atom and the thiolate sulfur atom. Both complexes are assigned a distorted octahedral geometry in which the ligands are arranged meridionally around the metal ions. The distortion from regular octahedral geometry is attributable to the restricted bite angles of the ligand.

Synthetic, spectroscopic and X-ray crystallographic structural study of the monomeric [Cu(pysme)(sac)(MeOH)] and dimeric [Cu(6mptsc)(sac)] 2 complexes [pysme=anion of the pyridine-2-carboxaldehyde Schiff base of S-methyldithiocarbazate, 6mptsc=the anion of the 6-methyl-2-pyridinecarbaldehydethiosemicarbazone and sac=the saccharinate anion

New mixed-ligand copper(II) complexes of empirical formulas [Cu(pysme)(sac) (CH 3OH)] and [Cu(6mptsc)(sac)] 2 have been synthesized and characterized by conductance, magnetic, IR and electronic spectroscopic techniques. X-ray crystallographic structure analyses of these complexes indicate that in both complexes the copper(II) ions adopt a five-coordinate distorted square-pyramidal geometry with an N 3SO donor environment. The Schiff bases are coordinated to the copper(II) ions as tridentate NNS chelates via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom. In the monomeric [Cu(pysme)(sac)(MeOH)] complex, the saccharinate anion acts as a monodentate ligand coordinating the copper(II) ion via the imino nitrogen atom whereas in the dimeric [Cu(6mptsc)(sac)] 2 complex, the sac anion behaves as a bridging bidentate ligand providing the imino nitrogen donor atom to one of the copper(II) ions and the carbonyl oxygen as a weakly coordinated axial ligand atom to the other Cu(II) ion. In both complexes, the copper(II) ions have distorted square-pyramidal environments. The distortion from an ideal square-pyramidal geometry is attributed to the restricted bite angles of the planar tridentate ligand.

The preparation and characterization of seven-coordinate tin(IV) complexes of the 2,6-diacetylpyridine Schiff bases of S-alkyl/aryl-dithiocarbazates and the X-ray crystal structure of the [Sn(dapsme)I 2] complex (dapsme=doubly deprotonated form of the 2,6-diacetylpyridine Schiff base of S-methyldithiocarbazate)

New tin(IV) complexes of empirical formula, Sn(SNNNS)I 2 (SNNNS=anionic form of the 2,6-diacetylpyridine Schiff bases of S-methyl- or S-benzyldithiocarbazate) have been prepared and characterized by a variety of physico-chemical techniques. The structure of Sn(dapsme)I 2 has been determined by single crystal X-ray crystallographic structural analysis. The complex has a seven-coordinate distorted pentagonal-bipyramidal geometry with the Schiff base coordinated to the tin(IV) ion as a dinegatively charged pentadentate chelating agent via the pyridine nitrogen atom, the two azomethine nitrogen atoms and the two thiolate sulfur atoms. The ligand occupies the equatorial plane and the iodo ligands are coordinated to the tin(IV) ion at axial positions. The distortion from an ideal pentagonal bipyramidal geometry is attributed to the restricted bite size of the pentadentate ligands.

Synthesis and crystal structure of Schiff base transition metal complex [Co(PMBP-smdtc)2]⋅2H2O

A cobalt(II) complex, [Co(PMBP-smdtc)2]⋅2H2O, in which PMBP-smdtc is the l-phenyl-3-methyl-4-benzoyl-5-pyrazolone Schiff base of S-methyldithiocarbazate, has been synthesized and characterized by IR spectrum and single crystal X-ray diffraction. The crystal is monoclinic: space group C2/c, with a = 12.455(2) A, b = 16.024(2) A, c = 20.513(3) A, β = 101.18(1)°, V = 4016.3(10) A3, and Z = 4. The cobalt ion is octahedrally coordinated by two tridentate Schiff base ligands with ONS donor atoms. The molecules are bridged together by two water molecules through H-bond along b axis and one-dimensional indented chain structure is formed.

Mono- and bis-chelated nickel(II) complexes of the di-2-pyridylketone Schiff base of S-methyldithiocarbazate and the X-ray crystal structure of the bis[ S-methyl-β- N-(di-2-pyridyl)-methylenedithiocarbazato]nickel(II) complex

The di-2-pyridylketone Schiff base of S-methyldithiocarbazate (Hdpksme) reacts with nickel(II) salts giving both mono- and bis-chelated complexes of empirical formulae, [Ni(dpksme)X] (dpksme=anioninc form of the Schiff base; X=NCS −, Cl −) and [Ni(dpksme) 2], respectively. These compounds have been characterized by magnetic and spectroscopic techniques. The mono-ligated nickel(II) complexes are four-coordinate and square-planar but the bis-ligand complex is six-coordinate and octahedral. The crystal and molecular structure of [Ni(dpksme) 2] has been determined by X-ray crystallography. The complex has a distorted mer-octahedral structure in which the ligands are coordinated as uninegatively charged tridentate chelating agents via the pyridine nitrogen atoms, the azomethine nitrogen atoms and the thiolate sulfur atoms. The distortion from regular octahedral geometry is ascribed to the restricted bite angles of the ligands. The ligand and its nickel(II) complexes exhibit weak antimicrobial activity against the pathogenic bacteria, S. dysenteriae, B. cercus, S. aureus and E. coli and the fungi, A. alternata and M. phaseolina.

Synthetic, spectroscopic and X-ray crystallographic structural studies on some copper(II) complexes of the 6-methylpyridine-2-carboxaldehyde Schiff base of S-methyldithiocarbazate

The complexes, [Cu(NNS)CH 3COO] and [Cu(NNS) 2] (HNNS=the 6-methylpyridine-2-carboxaldehyde Schiff base of S-methyldithiocarbazate) have been synthesized and characterized by a variety of physico–chemical techniques. The crystal structures of these complexes have also been determined by X-ray diffraction studies. The mono-ligated acetato complex has a square-planar structure with the copper(II) ion lying in an approximate plane of four coordinating atoms, three of which are supplied by the Schiff base and the fourth is provided by an oxygen of the anion. The bis-ligand copper(II) complex, [Cu(NNS) 2] has a distorted octahedral structure in which the Schiff bases are bound to the copper(II) ion as NNS tridentate ligands coordinating via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolato sulfur atom. The ligands are arranged meridionally around the copper(II) ion. Infrared and electronic spectral data for both complexes are consistent with their structures.

Molecular structure and spectral characteristics of bis( S -methyl- N -(2-pyridyl)methylendithiocarbazato)nickel(II), (Ni(NNS) 2 )

A nickel(II) complex of the pyridine-2-aldehyde Schiff base of S-methyldithiocarbazate (HNNS) has been synthesized and characterized by means of elemental analysis, IR and UV-vis spectra. The crystal structure of the complex has been determined by single-crystal X-ray diffraction. The complex crystallizes in the monoclinic, space P21/c, with a = 14.092(2), b = 16.886(2), c = 8.857(2)A; β = 105.78(3) °, V = 2028.2(6) A3, and Z = 4. The nickel atom is octahedrally coordinated by two uninegatively charged tridentate Schiff base in a mer-configuration via the pyridine nitrogen atom, azomethine nitrogen atom, and mecaptide sulfur atom.