The design and synthesis of the new amino acid Schiff base, N-(2-hydroxy-1-naphthalidene)phenylglycine (Hhnpg) has been described along with the single crystal X-ray crystallographic studies. Copper(II), nickel(II), cobalt(II), manganese(II) and zinc(II) complexes of Hhnpg were synthesized for the first time, and were characterized on the basis of elemental analysis, conductivity measurements, spectral (i.r., 1 H-n.m.r., u.v.-vis., e.p.r.), magnetic and thermal studies. The i.r. spectral studies of all the complexes exhibit a similar feature about the ligating nature of the ligand to the metal ions and reveal that the ligand has coordinated through the carbonyl oxygen, azomethine nitrogen and deprotonated hydroxyl oxygen. The conductance data of the complexes suggest them to be nonelectrolytes. The microbial activity of the ligand and the complexes was investigated.

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The oxidative addition of 2,4,6-tribromo-1,3,5-benzenetricarboxaldehyde (C6(CHO)3Br3) to 1, 2, or 3 equiv of [Pd(dba)2] ([Pd2(dba)3]·dba) and N∧N affords, respectively, the mono-, di-, or trinuclear complexes [Pd{C6(CHO)3Br2}Br(N∧N)] (N∧N = tmeda = N,N,N′,N′-tetramethylethylenediamine (1a), tbbpy = 4,4′-di-tert-butyl-2,2′-bipyridine (1b), bpy = 2,2′-bipyridine, (1c)); [{PdBr(N∧N)}2{μ2-C6(CHO)3Br}] (N∧N = tmeda (2a), tbbpy (2b)); or [{PdBr(N∧N)}3{μ3-C6(CHO)3}] (N∧N = tmeda (3a), tbbpy (3b)). The reactions of C6(CHO)3Br3 with a mixture of [Pd(dba)2] and PR3 lead, depending on the nature of the phosphine and the molar ratio of the reagents, to the mononuclear trans-[Pd{C6(CHO)3Br2}Br(PR3)2] (R = Ph (1d), R3 = Me2Ph (1e)) or the dinuclear [{trans-PdBr(PMe2Ph)2}2{μ2-C6(CHO)3Br}] (2e) complex. All attempts to prepare trinuclear phosphine complexes using this method of synthesis have been unsuccessful. However, displacement of the tbbpy ligand in 3b by an excess of PMe3 affords the trinuclear complex [{trans-PdBr(PMe3)2}3{μ3-C6(CHO)3}] (3f). The crystal structures of 1b, 1d, 2a·CDCl3, and 2e have been determined by X-ray diffraction studies.

A new tetradentate NOOO-donor ligand, N-(salicylidene)nitrosophenylglycine (H 2 snpg) has been designed, synthesized and structurally characterized. Copper(II), nickel(II), cobalt(II), manganese(II) and zinc(II) complexes of H 2 snpg have been prepared for the first time. The authenticities of the ligand and its metal complexes have been established on the basis of elemental analyses, molar conductance measurements, magnetic properties, spectral (i.r., 1 H-n.m.r., u.v.-vis. and mass) studies. The i.r. spectral studies of all the complexes exhibit a similar feature about the ligating nature of the ligand to the metal ions and revealed that the ligand has coordinated through the carbonyl oxygen, azomethine nitrogen, nitroso oxygen and deprotonated hydroxyl oxygen. The molar conductance data suggest them to be non-electrolytes. The antimicrobial activity of all the compounds was studied against Escherichia coli, Bacillus cirroflagellosus, Aspergillus niger and Candida albicans. All the complexes have shown a moderate to high fungal activity compared to the ligand.

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., 1 H-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 1 H-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.

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A new Schiff base, 2,6-diacetylpyridine bis(2-hydrazinobenzothiazole) (DPHB), has been designed, and synthesized by the condensation of 2,6-diacetylpyridine with 2-hydrazinobenzothiazole, and structurally characterized. Copper(II), cobalt(II), nickel(II), manganese(II), zinc(II), cadmium(II) and oxovanadium(IV) complexes of DPHB have been synthesized for the first time. Their structures have been elucidated on the basis of elemental analyses, conductance measurements, magnetic properties, spectral (i.r., 1 H-n.m.r., u.v.-vis., e.p.r. and FAB-mass) and thermal studies. The complexes exhibit an octahedral geometry around the metal centre. The conductance data of all the complexes suggest them to be 1:1 electrolytes. The X-band e.p.r. spectra of the copper(II) and oxovanadium(IV) complexes in the polycrystalline state at room (300 K) and liquid nitrogen temperature (77 K) were recorded and their salient features are reported. Thermal stabilities of the manganese(II) and zinc(II) complexes have been studied.

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