Gordon A. Bain

Structural studies of three isomeric forms of heterocyclic N(4)-substituted thiosemicarbazones and two nickel(II) complexes

Abstract Three structural forms have been isolated among four 2-formyl- and 2-acetylpyridine N(4)-substituted thiosemicarbazones reported. 2-Formylpyridine N(4)-methylthiosemicarbazone and 2-acetylpyridine N(4)-ethylthiosemicarbazone both exist as nonhydrogen bonding E isomers. 2-Formylpyridine 3-azabicyclo[3.2.2]nonylthiosemicarbazone crystallies as a hydrogen bondung Z isomer. The yellow 2-acetylpyridine 3-hexamethyleneiminylthiosemicarbazone crystallized with a bifurcated hydrogen bonding arrangement in which the N(3) hydrogen is formally positioned at N(2), making it tautomeric to the other two forms. Structures of four-coordinate nickel(II) complexes containing the monoanions of 2-formylpyridine 3-azabicyclo[3.2.2]nonylthiosemicarbazone and acetylpyrazine 3-hexamethyleneiminylthiosemicarbazone are included.

Copper(II) complexes of 2-benzoylpyridine 4N-substituted thiosemicarbazones

Abstract 2-Benzoylpyridine 4 N-substituted thiosemicarbazones commonly coordinate as neutral tridentate ligands to give five coordinate [Cu(HL)Cl 2 ] complexes when prepared in boiling isopropanol. However, when prepared in boiling ethanol, the anion (loss of the 3 N-hydrogen) coordinates as a tridentate ligand to give [CuLCl] complexes. Representative crystal structures of both stoichiometries have been determined. Spectral characterization of both the 2-benzoylpyridine 4 N-substituted thiosemicarbazones and their copper(II) complexes includes IR, UV-vis, EPR and NMR studies. Growth inhibition studies of the thiosemicarbazones and their complexes were performed against two human pathogenic fungi.

Synthetic and spectroscopic investigations of N(4)-substituted isatin thiosemicarbazones and their copper(II) complexes

Abstract A series of N(4)-substituted thiosemicarbazones of isatin were synthesized and their copper(II) complexes prepared from copper(II) chloride. X-ray crystal structures of two of the thiosemicarbazones, isatin 3-(hexamethylenimylthiosemicarbazone) and isatin 3-(N(4)-ethylthiosemicarbazone), have been solved and are compared with a previously published structure of isatin 3-(N(4)- p -tolythiosemicarbazone). The coordination chemistry of the copper(II) complexes of these and other isatin thiosemicarbazones is reported and discussed.

COPPER(II) AND NICKEL(II) COMPLEXES OF 2,3-BUTANEDIONE BIS(N(3)-SUBSTITUTED THIOSEMICARBAZONES)

Abstract Copper(II) and nickel(II) complexes of 2,3-butanedione bis(N(3)-methyl-, bis(N(3)-dimethyl-, bis(pyridyl- and bis(hexamethyleneiminylthiosemicarbazone), (H2Bu3M, H2Bu3DM, H2Bupip and H2Buhexim, respectively) have been prepared and studied spectroscopically. The four thiosemicarbazones have been characterized by their melting points, as well as IR, electronic and NMR (1H, 13C) spectra. The four coordinate copper(II) complexes have been studied by EPR spectroscopy and the copper(II) and nickel(II) complexes by a number of the spectroscopic techniques mentioned above. Upon formation of these complexes, loss of the N(2)H hydrogens occurs and the ligands coordinate to the metal centers as dianionic, tetradentate N2S2 ligands. The crystal structures of H2Bupip and the nickel(II) complex of 2,3-butanedione N3-methyl-phenylthiosemicarbazone, [Ni(Bu3MPh)], have been solved.

Structures and spectral properties of palladium(II) complexes of 2-acetylpyridine N(4)-dimethylthiosemicarbazone

Anions [loss of N(3) hydrogen of 2-acetylpyridine N(4)-dimethylthiosemicarbazone (HAc4DM)] coordinate in a planar conformation to a central palladium(II) through the pyridyl nitrogen, azomethine nitrogen and thiolato sulfur atoms. The fourth coordination site is occupied by either a bromo, chloro or a second Ac4DM ligand bonding via its thiolato sulfur atom. A crystal structure of [Pd(Ac4DM)Br] shows it to be planar, while the structure of [Pd(Ac4DM)2] has the unusual coordination of the two anions bonding differently to the palladium centre. Spectral and structural similarities and differences between these and related nickel(II) and copper(II) complexes are considered.

Nickel(II) and copper(II) complexes of 5-substituted-salicylaldehyde thiosemicarbazones

Binuclear nickel(II) and copper(II) complexes with four 5-methoxysalicylaldehyde N(3)-substituted thiosemicarbazones and nickel(II) complexes of four 5-nitro-salicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. I.r., electronic, and e.s.r. spectra of the complexes, as well as i.r., electronic, and 1H- and 13C-n.m.r spectra of the thiosemicarbazones, have been obtained. None of these compounds show significant growth inhibitory activity against the fungi Aspergillus niger and Paecilomyces variotii.

Copper(II) complexes of 2-formyl-,2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m-, N(4)-p-chlorophenylthiosemicarbazones

SummaryCuII complexes of 2-formyl, 2-acetyl- and 2-benzoylpyridine N(4)-o-, N(4)-m- and N(4)-p-chlorophenylthiosemicarbazones, coordinated either as a neutral or monoanionic ligand, have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as 1H- and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. Both the thiosemicarbazones and their CuII complexes show either modest or no growth inhibitory activity against Paecilomyces variotii. Some of the thiosemicarbazones demonstrated significant activity against tumour cell strains.

Copper(II) complexes of 2-formyl-, 6-methyl-2-formyl- and 2-benzoylpyridine N(4)-(2-methylpyridinyl)-,N(4)-(2-ethylpyridinyl)-and N(4)-methyl(2-ethylpyridinyl)thiosemicarbazones

SummaryThe title complexes of general formula [Cu(HL)Cl2] or [Cu(L)Cl] have been isolated and characterized by 1H and 13C-n.m.r., i.r. and electronic spectra. The i.r., electronic and e.s.r. spectral data for the CuII complexes are compared with those of previously studied complexes. The antitumour and antiviral activities of the thiosemicarbazones and their complexes are discussed.

Synthesis, crystal and molecular structure of 5-bromo-salicylaldehyde-2-methylthiosemicarbazonato(nitrato)Copper(II) monohydrate

Abstract The crystal and molecular structure of 5-bromo-salicylaldehyde-2-methyl-thiosemicarbazonato(nitrato)copper(II) monohydrate, [Cu(5BrSal2Me)(NO3)]·H2O, was determined by single-crystal X-ray diffraction. The thiosemicarbazone acts as a planar, tridentate, mon-negative ligand, coordinating through the phenolic oxygen, the azomethine nitrogen and the sulphur atom. The fourth position is occupied by an oxygen of the nitrato ligand. Two additional atoms are weakly bonded to the copper(II) ion giving a 4+1+1 geometry. A second oxygen atom from the nitrato ligand semi-coordinates, and the opposite side of the copper(II) centre is occupied by a bromine atom (phenyl ring) from a neighbouring molecule. As a consequence of this last interaction, the compound crystallizes as weekly bonded dimers. This compounds spectral data (i.e. IR, UV—vis, EPR) and measurements of its biological activity are included.

Binuclear copper(II) complexes of 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones

SummaryBinuclear copper(II) complexes with six 5-nitrosalicylaldehyde N(3)-substituted thiosemicarbazones have been prepared and characterized. I.r., electronic and e.s.r. spectra of the complexes, as well as i.r., electronic, and 1H-and 13C-n.m.r. spectra of the thiosemicarbazones, have been obtained. The crystal structure of a monomeric copper(II) complex of 5-nitrosalicylaldehyde piperidyl-thiosemicarbazone, H25NO2Sapip, grown from DMF solution, has been solved. Neither the thiosemicarbazones or their binuclear copper(II) complexes show growth inhibitory activity against Aspergillus niger, but the copper(II) complexes show some activity against the fungus Paecilomyces variotii.