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Two trinuclear Ni(II) complexes Ni3(L1)2(py)2(DMF)(H2O) (1) and Ni3(L2)2(py)2(DMF)2 (2) with two new trianionic pentadentate ligands N-(3,5-dimethylbenzoyl)-salicylhydrazide (H3L1) and N-(phenylacetyl)-5-nitrosalicylhydrazide (H3L2) have been synthesized and characterized by X-ray crystallography. Nickel ions in the two complexes have square-planar/octahedral/square-planar coordination. Central metal ion and two terminal metal ions in the two complexes are combined by two bridging deprotonated ligands, forming a trinuclear structural unit with an M-N-N-M-N-N-M core. Studies on the trinuclear Ni(II) complexes show that the β-branched N-acylsalicylhydrazide ligands with sterically flexible Cα methylene groups yield linear trinuclear Ni(II) complexes, while α-branched N-acylsalicylhydrazide ligands tend to form bent trinuclear Ni(II) complexes. Antibacterial screening data in a previous study indicates that bent trinuclear Ni(II) compound 1 is more active than linear compound 2 and less active than a tetranuclear nickel compound. [ABSTRACT FROM AUTHOR]

Abstract: Three polynuclear transition metal complexes [Mn8(DMF)8(L1)8]·4DMF (1), [Mn6(DMF)6(L2)6]·[Mn6(DMF)4(H2O)2(L2)6]·2DMF (2), [Cu3(L3)2(py)2] (3) of the pentadentate ligands N-acyl-salicylhydrazides were synthesized and characterized, their crystal structures were investigated. The oxidation state and properties of the central metal ions are important in crystal structure formation, trivalent Mn(III) ion which easily form stable octahedral coordination metallamacrocycle complexes, metallacrowns 1 and 2 were obtained; while bivalent Cu(II) ion is easier to form square planar, trinuclear complexes 3 was obtained. The steric effect of the N-acyl side chains also plays an important role in the structures of these polynuclear complexes. The magnetic property of 1 was also investigated. [Copyright &y& Elsevier]

Abstract: Two new trinuclear complexes, Cu3L2(py)2 (1) and Ni3L2(py)4 (2), have been synthesized and characterized, where L3− is N-2-methyl-acryloyl-salicylhydrazidate. Central metal ion and two terminal metal ions in the two complexes are combined by two bridging deprotonated L3− ligands, forming a bent trinuclear structure unit with an M–N–N–M–N–N–M core. The bent angles in complexes 1 and 2 are 167.6(1)° and 75.4(1)°, respectively. Three nickel ions in compound 2 exhibit alternating square-planar and octahedral geometries, while three copper ions in compound 1 follow square-planar mode. The studies in solution integrity and stability of compounds 1 and 2 show they are soluble and stable in DMF. UV–Vis titrations demonstrate compound 1 is stable in DMF even in the presence of excess metal ions. Antibacterial screening data indicate the two compounds all have stronger antimicrobial activities against the tested microorganisms than ligand. The trinuclear copper compound 1 is more active than monocopper compounds in the previous study, and the trinuclear nickel compound 2 is less active than tetranuclear nickel compound in the previous study. [Copyright &y& Elsevier]

Abstract: Two bent trinuclear Cu(II)/Ni(II) complexes [Cu3(L1)2(py)2] (1) and [Ni3(L2)2(py)4]·DMF (2), where H3L1 = N-(3,5-dimethylbenzoyl)-5-bromosalicylhydrazide, H3L2 = N-(3,5-dimethyl benzoyl)-salicylhydrazide, were synthesized and structurally characterized. In complex 1, all three Cu(II) ions take distorted planar square geometry, while in complex 2, the two terminal Ni(II) ions are distorted planar square, the central Ni(II) ion is octahedral. The magnetism of complex 1 was also studied. [Copyright &y& Elsevier]

Abstract: Four novel trinuclear copper(II)/nickel(II) complexes with four trianionic pentadentate ligands, N-(3-t-butylbenzoyl)-5-nitrosalicylhydrazide (H33-t-bbznshz), N-(3,5-dimethylbenzoyl)salicylhydrazide (H33,5-dmbzshz), N-(phenylacetyl)-5-bromosalicylhydrazide (H3pabshz) and N-(3-t-butylbenzoyl)salicylhydrazide (H33-t-bbzshz) have been synthesized and characterized by X-ray crystallography. These trinuclear compounds all have an M–N–N–M–N–N–M core formed by three metal ions and two ligands. The geometries of three Cu(II) ions in compound Cu3(3-t-bbznshz)2(H2O)(DMF)(py)2 ·DMF (1) alternate between distorted square pyramidal and square planar, while in compound Cu3(3,5-dmbzshz)2(py)2 (2), they are all square planar. Three Ni(II) ions in compound Ni3(pabshz)2(DMF)2(py)2 (3) and Ni3(3-t-bbzshz)2(py)4 ·2H2O (4) follow square-planar/octahedral/square-planar coordination geometry. Compounds 1, 2 and 4 are bent trinuclear, with the bend angles of 156.4°, 141.49° and 127.1°, respectively, while the three nickel ions in compound 3 are strictly linear, with an angle of 180°. Studies on the trinuclear Ni(II) complexes show that the β-branched N-acylsalicylhydrazide ligands with sterically flexible Cα methylene groups are easier to yield linear trinuclear Ni(II) complexes, while α-branched N-acylsalicylhydrazides ligands tend to form bent trinuclear Ni(II) complexes. Antibacterial screening data indicate that the trinuclear Cu(II) compound 2 is more active than 1 and mononuclear Cu(II) compound, bent trinuclear Ni(II) compound 4 is more active than linear compound 3 and less active than tetranuclear nickel compound in the previous study. [Copyright &y& Elsevier]

Abstract: A new trinuclear linear Ni(II) compound [Ni3(H2O)2(DMA)2(acshz)2]·2DMF (DMA=dimethylamine) (1) and a new Fe(III) 18-metallacrown-6 [Fe6(acbshz)6(DMF)(H2O)5]·5DMF (2), with two similar pentadentate ligands, N-acryloyl-salicylhydrazide (H3acshz) and N-acryloyl-5-bromosalicylhydrazide (H3acbshz) have been synthesized and characterized by X-ray crystallography. In compound 1, three nickel ions arrange in a strictly linear structure, adjacent molecules are linked by intermolecular H bonds to form a 2D infinite wave-like structure. In compound 2, the ring of the metallacrown is consisted of six interlink [Fe–N–N] repeated units through hydrazide N–N group bridging. It is the first metallacrown that the coordination environments of metal ions in the cycle ring are different, and these differences make the two faces of the disc-shaped hexanuclear ring do not have opposite chiralities. The studies in solution integrity and stability of the metallacrown 2 show it is soluble and stable in DMF. UV–Vis titrations demonstrate the metallacrown 2 is stable in DMF even in the presence of excess metal ions. Antibacterial screening data indicate the two compounds all have antimicrobial activities against the tested microorganisms. The activities of metallacrown 2 are stronger than trinuclear compound 1. [Copyright &y& Elsevier]