Coordination chemistry and bioactivity of Ni2+, Cu2+, Cd2+ and Zn2+ complexes containing bidentate schiff bases derived from S-benzyldithiocarbazate and the X-ray crystal structure of bis[S-benzyl-β-N-(5-methyl-2-furylmethylene)dithiocarbazato]cadmium(II).

New bidentate isomeric NS and NS′ Schiff bases were derived from the condensation of S-benzyldithiocarbazate (SBDTC) with 5-methyl-2-furyldehyde and 2-furyl-methylketone. Reaction of NS ligand with Ni(II), Cu(II), Cd(II) and Zn(II) salts gave solid complexes. Only the Ni(II) complex of the NS′ ligand was isolated. All complexes were characterized by a variety of physico-chemical techniques, viz. elemental analyses, molar conductivity, i.r. and electronic spectral studies. The Schiff bases behaved as uninegatively charged bidentate ligands. Square-planar structures have been proposed for the Cu(II) complex containing the NS Schiff base ligand and the Ni(II) complexes of the bidentate NS and NS′ Schiff base ligands. Single crystal X-ray diffraction study of [Cd(NS)2] showed that the complex was bis chelated with a distorted tetrahedral structure. The antimicrobial properties of the Schiff bases and their metal complexes indicate that the organic compounds are stronger antifungal agents than their complexes with the metals studied. However, the zinc complex of the Schiff base, S-benzyl-β-N-(5-methyl-2-furyl)methylenedithiocarbazate, (NS), was found to be highly active against CEM-SS (Human cell T-lymphoblastic leukemia) with a CD50 value of 2.0 μg cm−3, while [Cd(NS)2] was moderately active with a CD50 value of 4.95 μg cm−3. None of the compounds were found to be active against HT-29 (Human colon adenocarcinoma cells). The bioactivity of a previously reported tridentate NNS Schiff base (SBD1) and its metal complexes with nickel(II) and copper(II) are also discussed

Triethyl­ammonium bis­(2-oxido-2,2-diphenyl­acetato-κ2 O 1,O 2)anti­monate(III)

The coordination around the Sb atom in the title compound, (C6H16N)[Sb(C14H10O3)2], is fourfold in a pseudo-trigonal-bipyramidal pattern in which one of the equatorial sites is occupied by the stereoactive lone pair of electrons. The four ligating atoms comprise the hydoxylate and carboxyl­ate O atoms from two independent benzilate ligands, each of which forms a five-membered chelating ring, spanning an axial and an equatorial site about the Sb atom. The hydroxy­late atoms occupy the two equatorial sites, and the carboxyl­ate atoms are in the pseudo-axial sites; the O—Sb—O angle is 147.72 (5)°. One carboxyl­ate group shows quite different bond lengths from those of the other group; one O atom is clearly the carbonyl atom and the other O atom the hydroxy­late atom. In the other ligand, there is less distinction in the C—O bonds. This is presumably related to the carbonyl O atom being the acceptor atom of a strong N—H⋯O hydrogen bond, which links the ammonium cation to the Sb complex anion

Di-l-methacrylato-j4O:O0-bis[aquabis(1,10-phenanthroline-j2N,N0)-copper(II)] dinitrate dihydrate

The title complex, [Cu2(C4H5O2)2(C12H8N2)2(H2O)2](NO3)2- 2H2O, contains a dimeric [Cu2(C4H5O2)2(C12H8N2)2- (H2O)2]2+ dication with two five-coordinated CuII ions linked by two methacrylate ions in a syn–syn bridging arrangement.The dication possesses pseudo-twofold rotational symmetry.The pentacoordination of each CuII ion has a distorted squarepyramidal geometry, with two N donors from a phenanthroline ligand and two carboxylate O atoms occupying basal sites and the apical position being occupied by a water molecule. In the crystal packing, molecules are linked to form a threedimensional framework by O—H O and C—H O hydrogen bonds and – interactions [centroid–centroid distances of 3.6039 (15), 3.5301 (15), 3.6015 (15),3.6496 (15) and 3.6858 (15) A ° ]

Synthesis and characterization of Zn(II) and Cd(II) complexes of S-benzyl-β-N-(2-pyridyl)methylenedithiocarbazate (HNNS): bioactivity of the HNNS Schiff base and its Zn(II), Cu(II) and Cd(II) complexes and the X-ray structure of the [Zn(NNS)2] complex

A tridentate Schiff base having HNNS donor sequence was prepared by condensing S-benzyldithiocarbazate (NH2NHCSSCH2Ph) with pyridine-2-carboxaldehyde. Complexes of this ligand, pyCHNNHCSSCH2Ph(HNNS), with Cu(II), Cd(II) and Zn(II) were synthesized and characterized by elemental analyses and various physico-chemical techniques. X-ray crystallographic analysis shows that the Zn(II) complex, [Zn(NNS)2], is six-coordinate and has a distorted octahedral structure with the ligand coordinated to the Zn(II) ion as a uninegatively charged tridentate chelating agent via the pyridine nitrogen, the azomethine nitrogen and the mercaptide sulfur atoms. Distortions from the regular octahedral geometry are attributed to the restricted bite angles of the planar NNS tridentate ligand. The Cu(II) complex, [Cu(NNS)Cl], was paramagnetic with a square-planar stereochemistry while the Cd(II) complex, [Cd(NNS)Br], was diamagnetic and is suggested to have a tetrahedral structure. The Schiff base and its complexes were screened for antimicrobial, cytotoxic and antioxidant activities. Disc diffusion methods were employed for antimicrobial assays against eight pathogenic microorganisms. The Schiff base and the complexes do not display activities against any of the microorganisms. The Schiff base was cytotoxic with a CD50 value of 5.90 μg ml−1 against the T-lymphoblastic leukemic cells while the Cu(II) and Cd(II) complexes were strongly cytotoxic with CD50 values of 2.20 and 2.30 μg ml−1, respectively. The Cu(II) and Cd(II) complexes were also effective against colon cancer cells with CD50 values of 2.60 and 3.10 μg ml−1, respectively. SBDTC showed a higher antioxidant activity than the α-tocopherol (vitamin E) and was comparable with butylated hydroxytoluene (BHT), a commercially used synthetic antioxidant

Biological activity of palladium(II) and platinum(II) complexes of the acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate and the X-ray crystal structure of the [Pd(asme)2] (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) complex

Palladium(II) and platinum(II) complexes of general empirical formula, [M(NS)2] (NS=uninegatively charged acetone Schiff bases of S-methyl- and S-benzyldithiocarbazate; M=PtII and PdII) have been prepared and characterized by a variety of physicochemical techniques. Based on conductance, IR and electronic spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(asme)2] complex (asme=anionic form of the acetone Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted cis-square planar structure with the ligands coordinated to the palladium(II) ions as uninegatively charged bidentate NS chelating agents via the azomethine nitrogen and the mercaptide sulfur atoms. The distortion from a regular square-planar geometry is attributed to the restricted bite angles of the ligands. Antimicrobial tests indicate that the Schiff bases exhibit strong activities against the pathogenic bacteria, Bacillus subtilis (mutant defective DNA repair), methicillin-resistant Staphylococcus aureus, B. subtilis (wild type) and Pseudomonas aeruginosa and the fungi, Candida albicans (CA), Candida lypotica (2075), Saccharomyces cerevisiae (20341) and Aspergillus ochraceous (398)—the activities exhibited by these compounds being greater than that of the standard antibacterial and antifungal drugs, streptomycin and nystatin, respectively. The palladium(II) and platinum(II) complexes are inactive against most of these organisms but, the microbe, Pseudomonas aeruginosa shows strong sensitivity to the platinum(II) complexes. Screening of the compounds for their cytotoxicities against T-lymphoblastic leukemia cancer cells has shown that the acetone Schiff base of S-methyldithiocarbazate (Hasme) exhibits a very weak activity, whereas the S-benzyl derivative (Hasbz) is inactive. However, the palladium(II) complexes exhibit strong cytotoxicities against this cancer; their activities being more than that of the standard anticancer drug, tamoxifen. The [Pt(asme)2] complex exhibits a very weak cytotoxicity, whereas [Pt(asbz)2] is inactive against leukemic cells

Synthesis, characterization and bio-activity of S-2-picolyldithiocarbazate (S2PDTC), some of its Schiff bases and their Ni(II) complexes and X-ray structure of S-2-picolyl-β-N-(2-acetylpyrrole)dithiocarbazate

A new dithiocarbazate ligand, S-2-picolyldithiocarbazate (S2PDTC) was synthesized using 2-picolylchloride hydrochloride. Tridentate Schiff bases were prepared by condensation of S-2-picolyldithiocarbazate (S2PDTC) with pyridine-2-carboxaldehyde (NNS′), 2-acetylpyrrole (NNS″) and 2-acetylthiophene (NSS), while a bidentate Schiff base (NS) was prepared by condensing the S2PDTC with 2-acetylfuran. Complexes of S2PDTC and its Schiff bases with Ni(II) salts were synthesized and characterized by elemental analyses and various physico-chemical techniques. A square-planar structure has been proposed for the diamagnetic [Ni(S2PDTC)2] and [Ni(NNS″) · Cl] complexes while [Ni(NS) · Cl] complex was dimeric. Complexes of [Ni(NNS′)2] and [Ni(NSS)2] were paramagnetic with octahedral stereochemistry. S2PDTC showed activity against bacteria and fungi (inhibitory zones above 15 mm). The NS and NSS Schiff bases showed activity toward a number of the bacteria assayed, while the NS and NSS Schiff bases, and the [Ni(NNS″) · Cl] and [Ni(NS) · Cl] complexes were found to be active only against C. lypolytica (2075). S2PDTC proved moderately active against HT-29 and weakly active toward CEM-SS with CD50 values of 9.5 and 24.0 μg cm−3, respectively, while among its Schiff bases reported herein, only the NNS′ Schiff base showed strong activity toward CEM-SS (Human cell T-lymphoblastic leukemia) and HT-29 (Human colon adenocarcinoma cells) with CD50 values of 2.3 μg cm−3. All of the Ni(II) complexes were inactive against CEM-SS cancer cells

Complexes of a tridentate ONS Schiff base. Synthesis and biological properties

Several new complexes of a tridentate ONS Schiff base derived from the condensation of S-benzyldithiocarbazate with salicylaldehyde have been characterised by elemental analyses, molar conductivity measurements and by i.r. and electronic spectra. The Schiff base (HONSH) behaves as a dinegatively charged ligand coordinating through the thiolo sulphur, the azomethine nitrogen and the hydroxyl oxygen. It forms mono-ligand complexes: [M(ONS)X], [M=NiII, CuII, CrIII, SbIII, ZnII, ZrIV or UVI with X = H2O, Cl]. The ligand produced a bis-chelated complex of composition [Th(ONS)2] with ThIV. Square-planar structures are proposed for the NiII and CuII complexes. Antimicrobial tests indicate that the Schiff base and five of the metal complexes of CuII, NiII, UVI, ZnII and SbIII are strongly active against bacteria. NiII and SbIII complexes were the most effective against Pseudomonas aeruginosa (gram negative), while the CuII complex proved to be best against Bacillus cereus (gram positive bacteria). Antifungal activities were also noted with the Schiff base and the UVI complex. These compounds showed positive results against Candida albicans fungi, however, none of them were effective against Aspergillus ochraceous fungi. The Schiff base and its zinc and antimony complexes are strongly active against leukemic cells (CD50 = 2.3–4.3 μg cm−3) while the copper, uranium and thorium complexes are moderately active (CD50 = 6.9–9.5 μg cm−3). The nickel, zirconium and chromium complexes were found to be inactive