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The mononuclear CuII complex [CuL(H2O)]·2H2O (1) with a diazamesocyclic ligand bearing two functional carboxylic donor groups, 1,5-diazacyclooctane-N,N′-diacetate acid (H2L), has been synthesized and characterized by elemental analyses, thermal analyses and IR spectrum. The crystal structure of 1 has been determined by X-ray diffraction analysis, which revealed that the CuII center coordinates to the tetradentate chelated ligand L and an axial water molecule, and the 1,5-diazacyclooctane (DACO) moiety adopts a boat/chair conformation that inhibits the axial coordination at the metal center to form this penta-coordinated pyramidal (CuN2O3) complex. The most striking feature of this structure is the formation of a novel two-dimensional joint-ladder like architecture through multiple inter- and intramolecular O–H⋯O hydrogen bonds. The solution behaviors of 1 have been further investigated by conductance, UV–Vis and ESR techniques. [Copyright &y& Elsevier]

A series of four-coordinated monomeric CuII, CoII, and NiII complexes of a tetradentate diazamesocyclic ligand containing bulky phenolate donor pendants, [CuL] (1), [Cu(HL)]ClO4 (2), [CoL] (3), and [NiL] (4), where H2L=1,4-bis-(3-tert-butyl-5-methyl-2-hydroxybenzyl)-1,4-diazacycloheptane, have been synthesized and characterized by elemental analyses, IR, UV–vis and ESR spectra. The crystal structure of complex 1 has been determined by X-ray diffraction analysis. [Copyright &y& Elsevier]

A novel phenoxo-bridged dinuclear CoII complex with a diazamesocyclic ligand bearing one additional phenol functional donor group, [CoLCl]2·2C3H6O (1) (where HL=1-(2-hydroxybenzyl)-1,5-diazacyclooctane), has been synthesized and characterized by elemental analyses, conductance, thermal analyses, IR and UV–vis spectra. The crystal structure of complex 1 has been determined by X-ray diffraction technique, which reveals that it is a neutral complex and resides on a crystallographic inversion center. The two CoII centers bridged by the phenoxo groups are penta-coordinated, taking a coordination sphere in the midst of the ideal square-pyramid and trigonal bipyramid. 1,5-Diazacyclooctane of the ligand takes a boat/chair conformation and an H atom from it effectively blocks the axial coordination site opposite the Cl− ligand to form CoN2O2Cl geometry. The crystal structure is stabilized by the N–H⋯O hydrogen bond between the amino group and the acetone molecule. [Copyright &y& Elsevier]

A new potential tetradentate ligand, 1,4-bis(N-1-methylimidazol-2-ylmethyl)-1,4-diazacycloheptane (l), together with its CuII complex [CulCl]ClO4 (1), has been reported. The crystal structure of 1, determined by single-crystal X-ray analysis, shows that it is in chiral P212121 space group. The CuII centre is penta-coordinated in square pyramidal geometry and the diazacycloheptane (DACH) ring adopts normal boat configuration. The most striking feature of this complex is the formation of a 3D network bridged through the C–H⋯Cl hydrogen bonds with the perchlorate anions in the cavities, and stabilized via π–π stacking interactions along the a-direction. The solution behaviour of 1 has been further investigated by UV/Vis and ESR techniques. [Copyright &y& Elsevier]

Two mononuclear RuII complexes of polypyridyl ligands, cis-[Ru(bpy)2(4,4′-bpy)Cl](PF6)·H2O (1) and cis-[Ru(phen)2(CH3CN)2](PF6)2 (2) (bpy=2,2′-bipyridyl, 4,4′-bpy=4,4′-bipyridyl, and phen=1,10-phenanthroline), have been synthesized and characterized by elemental analyses, IR and UV–vis spectra. The crystal structures of both complexes have been determined by X-ray diffraction, indicating that each RuII center is hexa-coordinated (RuN5Cl for 1 and RuN6 for 2) and takes a distorted octahedral geometry. The favored feature of both complexes is that they are quite useful complex precursors for further constructing new functional architectures. [Copyright &y& Elsevier]