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

Summary Binuclear 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.     

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 4-formylantipyrine N(4)-substitutedthiosemicarbazones

Copper(II) complexes between three 4-formylantipyrine N(4)-substituted thiosemicarbazones and four copper(II) salts 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. Both mononuclear and binuclear complexes have been formed with bridging ligands for the latter, being either chloro or acetato. The stoichiometries of the complexes are dependent on both the steric requirements of the thiosemicarbazone ligands and the electronic effects of their N(4)-substituents.     

Copper(II) complexes of 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones

Mononuclear and binuclear copper(II) complexes with four 4-acetamidobenzaldehyde N(4)-substituted thiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. I.r., electronic, and e.s.r. spectra of the complexes, as well as i.r., electronic, and n.m.r. spectra of the thiosemicarbazones, have been obtained. These thiosemicarbazones coordinate as anionic or neutral ligands via the thiosemicarbazone moiety's imine nitrogen and thiolate/thione sulfur, the former on loss of the hydrazido hydrogen, N(2)H.     

Copper(II) complexes of formylpyrazine N(4)-substituted thiosemicarbazones

Copper(II) complexes of formylpyrazine N(4)-substituted thiosemicarbazones coordinated either as neutral or monoanionic ligands, [M(HL)X2] and [M(L)X], respectively, have been prepared and characterized. I.r., electronic and e.s.r spectra of the complexes, as well as 1H-n.m.r. spectra of the thiosemicarbazones, have been obtained. The N(4)-dialkyl and azacyclothiosemicarbazones and their copper(II) complexes show significant growth inhibitory activity against both Aspergillus niger and Paecilomyces variotii.     

Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones

Summary Copper(II) complexes of 6-methyl-2-acetylpyridine N(4)-substituted thiosemicarbazones, coordinated either as a neutral or a monoanionic ligand, have been prepared and characterized. I.r., electronic and e.p.r. spectra of the complexes, as well as¹H- and¹³C-n.m.r. spectra of the thiosemicarbazones, have been recorded. Both the thiosemicarbazones and their copper(II) complexes show either modest or no growth inhibitory activity againstAspergillus niger, but theN(4)-dialkyl- and 3-azacyclo-derivatives, and particularly their copper(II) complexes, have considerable activity againstPaecilomyces variotii.     

Template synthesis,characterization and electrochemical studies of copper(II) macrocyclic complexes derived from 4-methyl-2,6-di(formyl/benzoyl) phenol and diamines

Copper(II) macrocyclic complexes [Cu(L)Cl2]·2H2O (1,2) have been synthesized from the copper(II)-directed condensation of 4-methyl-2,6-diformylphenol (1) or 4-methyl-2,6-dibenzoylphenol (2) with diamines [1,2-diaminopropane (a), 1,3-diaminopropane (b) and o-phenylenediamine (c)] in EtOH in high yields. These complexes are monomeric, non-electrolytes and paramagnetic, indicating a distorted octahedral geometry around copper, which is supported by i.r., electronic, e.s.r. and magnetic susceptibility measurements. Electrochemical studies of (1) and (2) using c.v. indicate an irreversible cathodic peak (ca. –0.65 to –0.76 V) corresponding to reduction of copper(II) to copper(I) and the diffusion-controlled nature of the electrode process.     

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

Mononuclear copper(II) complexes with 2-aminoacetophenone thiosemicarbazone and three N(4)-substituted thiosemicarbazones have been prepared in ethanolic solution and characterized by physical and spectral methods. 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 2-aminoacetophenone thiosemicarbazones coordinate as neutral ligands via the thiosemicarbazone moiety's azomethine nitrogen and thione sulfur, except for the piperidylthiosemicarbazone, which undergoes deprotonation and coordinates via the thiolato sulfur, as well as through the azomethine nitrogen. Complexes formed in the presence of triethylamine also form complexes with the anionic form of these thiosemicarbazones.     

Copper(II), nickel(II), cobalt(II) and oxovanadium(IV) complexes of substituted β-hydroxyiminoanilides

Complexes of the general formula, ML₂ [M = Cu^II, Ni^II, Co^II and OV^IV; L = 1,2,3,5,6,7,8,8a-octahydro-3-hydroxyimino-N-(4-X-phenyl)-l-phenyl-5-(phenylmethylene)-2-naphthalenecarboxamide (X = H, Me, OMe, Cl)] have been prepared and characterized on the basis of elemental analysis, magnetic moments and i.r., e.p.r. and electronic spectra. These metal complexes contain the N₄ chromophore with the ligand coordinating through nitrogens of the azomethine and deprotonated anilide functions. C.v. measurements indicate that the copper(II) complexes are quasi-reversible in acetonitrile solution. Square planar and square pyramidal structures are assigned respectively to the copper(II) and oxovanadium(IV) complexes, whereas tetrahedral geometry is assigned to the nickel(II) and cobalt(II) complexes. Deprotonated anilide nitrogen is involved in coordination and the presence of an electron-donating group para to the anilide function decreases the ΔE values of the d–d transitions while the value is found to increase when electron-withdrawing groups are substituted. Line spacing in the e.p.r. spectra of the copper(II) and oxovanadium(IV) complexes increases when methyl group is para to the anilide group, and decreases when this group is replaced by methoxy or chloro. The ν(C–N) of the anilide group and the ν(C-N) of the azomethine function of the oxime metal complexes are metal-sensitive and the blue shift for the above stretching frequencies follows the order: copper(II) > oxovanadium(IV) > nickel(II) ≈ cobalt(II). This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis and spectroscopic characterization of transition metal complexes of a 12-membered tetraaza [N<Subscript>4</Subscript>] macrocyclic ligand and their biological activity

Cobalt(II), nickel(II) and copper(II) complexes are synthesized with 1,3,7,9-tetraaza- 4,6,10,12-tetraphenyl-2,8-dithiacyclododecane, a tetradentate ligand (L) and characterized by elemental analysis, molar conductance measurements, magnetic susceptibitity measurements, mass, i.r., electronic and e.p.r. spectral studies. All the complexes are non-electrolytes so they may be formulated as [M(L)X₂] [where, M = Co(II), Ni(II) and Cu(II) and X = Cl⁻ and NO ₃ ⁻ ]. All the complexes are of high spin type. On the basis of i.r., electronic and e.p.r. spectral studies an octahedral geometry has been assigned for Co(II) and Ni(II) complexes and tetragonal geometry for Cu(II) complexes. The antimicrobial activities of the ligand and its complexes, as growth inhibiting agents, have been screened in vitro against two different species of bacteria and plant pathogenic fungi.     

Synthesis,characterization and catalytic studies of iron(III), cobalt(II), nickel(II) and copper(II) complexes containing triphenylphosphine and β-diketones

A series of new β-diketonato complexes have been synthesized from the reactions of iron(III), cobalt(II), nickel(II) and copper(II) Ph₃P complexes with β-diketones (acetylacetone, benzoylacetone and dibenzoylmethane). All the complexes have been characterized by elemental analyses, spectral studies (i.r., electronic., magnetic., e.p.r., ¹H-n.m.r.) and cyclic voltammetry. The new complexes have been used as catalysts for aromatic coupling and oxidation reactions. Higher catalytic activity has been observed for the nickel(II) complexes compared to the other complexes.     

Crystal Structure of 2-[2-hydroxy-3-methoxyphenyl]-3-[2-hydroxy-3-methoxybenzylamino]-1,2-dihydroquinazolin-4(3H)-one and the Synthesis, Spectral and Thermal Investigation of its Transition Metal Complexes

A new 1,2-dihydroquinazolin-4(3H)-one ligand, 2-[2-hydroxy-3-methoxyphenyl]-3-[2-hydroxy-3-methoxybenzylamino]-1,2-dihydroquinazolin-4(3H)-one (Hmpbaq), formed by the condensation of 2-aminobenzoylhydrazide with 2-hydroxy-3-methoxybenzaldehyde and its copper(II), nickel(II), cobalt(II), manganese(II), zinc(II) and cadmium(II) complexes, have been synthesized. Their structures have been elucidated on the basis of elemental analyses, conductance measurements, magnetic moments, spectral (i.r., ¹H-n.m.r., u.v.–vis., e.p.r. and FAB-mass) and thermal studies. The formation of 1,2-dihydroquinazolin-4(3H)-one rather than hydrazone in the reaction of 2-aminobenzoylhydrazide with 2-hydroxy-3-methoxybenzaldehyde is confirmed by the ¹H-n.m.r. spectra and single crystal X-ray diffraction studies. The tridentate behavior of the ligand was proposed on the basis of spectral studies. X-band e.p.r. spectra of the copper(II) and manganese(II) complexes in the polycrystalline state at room temperature and liquid nitrogen temperature were recorded and their salient features are reported. Thermal stabilities of the manganese(II) and zinc(II) complexes have been studied.     

Synthesis and spectral characterization of 1-phenylglyoxal bis{N(4)ethylthiosemicarbazone} and its metal complexes

Nickel(II), copper(II), zinc(II), and cadmium(II) complexes of 1-phenylglyoxal bis{N(4)-ethylthiosemicarbazone} have been synthesized and characterized spectroscopically. The bis(thiosemicarbazone) and its diamagnetic complexes have been characterized by their melting points, i.r., electronic, mass and ¹H n.m.r. spectra. The four-coordinate copper(II) complex was also studied by e.s.r. spectroscopy. Upon coordination, the loss of a proton from each thiosemicarbazone moiety occurs, and the bis(thiosemicarbazone) coordinates to nickel(II) and copper(II) as a dianionic, tetradentate N₂S₂ ligand; but for zinc(II) and cadmium(II), mass spectral results suggest the formation of binuclear complexes.     

An e.s.r. study of copper(II) complexes of N-hydroxyalkylsalicylideneimines

X-band e.s.r. spectra of copper(II) complexes of empirical formula Cu(Sal.NCH2CH2O)X (where X= H2O, py or Cl) and [Cu(Sal.NCH2CH2CH2O)]2 (Sal.N= OC6H4CHN) in solid and solution states at room temperature and at 77K are reported. In frozen solution at 77K the spectra show axial symmetry with a dx2−y2 ground state. The in-plane π-bonds show a moderate degree of covalence, while the out-of-plane π-bonds possess ionic character. The orbital populations of these complexes are 70.9, 81.3, 93.3 and 82.4% respectively, indicating a dx2−y2 ground state. This revised version was published online in June 2006 with corrections to the Cover Date.     

Spectral studies of metal complexes of a new type of bis(thiosemicarbazone)

Cobalt(II), nickel(II) and copper(II) complexes of two new bis(di-2-pyridyl ketone) dithiosemicarbazones have been prepared in EtOH solution and characterized by physical and spectral methods. The bis(di-2-pyridyl ketone) dithiosemicarbazones were prepared from dithiosemicarbazides derived from piperazine and N,N-dimethylethylenediamine. N.m.r., i.r., and electronic spectra of the dithiosemicarbazones and their complexes along with e.s.r. spectra of the copper(II) complexes have been recorded. The complexes are bi-, tri- and tetranuclear and involve the dithiosemicarbazones coordinating as dianionic, anionic and neutral ligands.     

Mono and dinuclear copper(II) complexes of 2,4,6-tris(2-pyridyl)-1, 3,5-triazine and halide or pseudohalide ions: Synthesis and spectral studies

Summary By inhibiting the copper(II) assisted TPT (TPT = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) hydrolysis, monomeric and dimeric copper(II) complexes having as general formulae Cu(TPT)X, · nH₂O (X = Cl, Br, NCS, NCO or N₃) and [Cu(TPT)X]₂(PF₆)₂ · nH₂O (X = Cl, Br, NCS or N₃) have been synthesized and characterized by i.r., electronic and e.p.r. spectra, x-ray powder diffraction and analytical data. Spectroscopic results indicate five-coordinate geometry around the copper(II) ion, intermediate between trigonal-bipyramid and square-pyramid structures. The half-field absorption in the M_S = 2 region of powdered X-band e.p.r. spectra has been observed for the dimeric species.     

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

The title complexes of general formula [Cu(HL)Cl2] or [Cu(L)Cl] were isolated from boiling EtOH. The thiosemicarbazones have been characterized by their 1H- and 13C-n.m.r., i.r. and electronic spectra. The i.r., electronic and e.s.r. spectra of the copper(II) complexes are compared with data on previously studied complexes. The antitumour and antiviral activities of the thiosemicarbazones and their complexes are discussed. This revised version was published online in June 2006 with corrections to the Cover Date.     

Synthesis,magnetic and spectral studies of iron(III), cobalt(II,III), nickel(II), copper(II) and zinc(II) complexes of 2–formylpyridine N(4)-antipyrinylthiosemicarbazone

2–Formylpyridine N(4)-antipyrinylthiosemicarbazone and its metal complexes have been synthesized and characterized. Elemental analyses, molar conductivities, magnetic measurements and spectral (i.e., i.r., electronic, n.m.r. and e.s.r.) studies have been used to characterize the complexes. The i.r. spectra show that the thiosemicarbazones behave as bidentate or tridentate ligands either in the thione or thiolato form. Ligand field parameters have been calculated and the proposed stereochemistries are based on the various physical and spectral methods.     

Copper(II) and nickel(II) complexes of the bis{N(3)-substituted thiosemicarbazones} of phenylglyoxal and 1-phenylpropane-1,2-dione

Copper(II) and nickel(II) complexes of phenylglyoxal and phenylpropane-1,2-dione bis{N(3)-methyl-, bis{N(3)-dimethyl-, bis{piperidylthiosemicarbazone} have been prepared and studied spectroscopically. The six bis(thiosemicarbazones) have been characterized by their melting points, as well as i.r., electronic and 1H-n.m.r. spectra. The four-coordinate copper(II) complexes have been studied by e.s.r. spectroscopy, and the copper(II) and nickel(II) complexes by spectroscopic techniques mentioned above. Upon formation of these complexes, the loss of protons from each thiosemicarbazone moiety occurs, and the bis(thiosemicarbazones) coordinate to the metal centres as dianionic, tetradentate N2S2 ligands.     

Five coordinated complexes of divalent nickel and copper with ligands derived from acid hydrazides and acetylacetone

Summary Picolinic acid hydrazide (PH) and isonicotinic acid hydrazide (INH) react with acetylacetone to form complexes, containing open chain tetradentate ligands, through anin situ process in the presence of nickel and copper salts. The complexes were isolated and characterised as five-coordinate with the aid of analyses, magnetic, e.s.r., electronic and i.r. spectral studies.Attempts to obtain the free ligand were unsuccessful, but its solid complexes can be isolated. Acetylacetonebispicolinoyl hydrazone Ac(PH)₂ coordinates through azomethine and pyridine nitrogen atoms while acetylacetonebisisonicotinoyl hydrazone Ac(INH)₂ does so through azomethine nitrogens and amido oxygen atoms, giving rise to complexes of the MAc(PH)₂X or MAc(INH)₂X type where X=Cl, Br, NO₃ or NCS and M=nickel(II) and copper(II). Magnetic, e.s.r. and electronic spectra are consistent with five coordinate geometries incorporating one anion on the axial positions. Various ligand field parameters have been calculated and the amount of distortion assessed in terms of DT/DQ. The metal-ligand vibrations in the far i.r. are discussed.