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Three new mononuclear complexes of copper(II), viz. [Cu(L)(N 3 )Cl] ( 1 ), [Cu(L′)(H 2 O)]ClO 4 ( 2 ) and [Cu(L″)] ( 3 ) where L = N -(3-aminopropyl)- N -methylpropane-1,3-diamine, L′ = 2-( N -{3-[(3-aminopropyl)(methyl)amino]propyl}ethanimidoyl)phenolate ion and L″ = 2,2′-{(methylimino)bis[propane-3,1-diylnitrilo(1 E )eth-1-yl-1-ylidene]}diphenolate ion, have been prepared. The synthesis of complex 1 has been achieved by reacting copper chloride with the triamine (L) and sodium azide in a 1:1:1 M ratio. The other two compounds have been synthesized by the reaction of copper perchlorate with the same triamine, L, plus 2-hydroxyacetophenone in a molar ratio of 1:1:1 (for 2 ) and 1:1:2 (for 3 ), so that the respective tetradentate and pentadentate Schiff bases HL′ and H 2 L″ are formed in situ to bind the copper(II) ions. The complexes have been characterized by microanalytical, spectroscopic and single crystal X-ray diffraction studies. Structural studies reveal that the mononuclear units of all the three complexes adopt a distorted square pyramidal geometry and are held together by either intermolecular H-bonding (in 1 and 2 ) or C–H⋯π interactions (in 3 ) to form supramolecular networks in the solid state.

A tetranuclear ‘stepped wise’ copper(II) complex, [Cu4(μ2-OH)2(μ3-OH)2(2,2′-bipy)4Cl2]Cl2·6H2O has been synthesized and the crystal structure of the complex redetermined. The magnetic behavior has been investigated in the temperature range 300–4.2 K based on its novel binding modes of the OH−, i.e. OH− anions bridge the copper(II) centers in a bidentate (μ-2) as well as tridentate (μ-3) fashion and this shows ferromagnetic interactions. The fit of the experimental data was made by the irreducible tensor operator formalism (ITO) using the clumag program based on the Hamiltonian; H=−J1(S1S2+S3S4)−J2(S1S4)−J3(S1S3+S2S4) and the best fit parameters, assuming the g factors are identical and J2=J3, leads to J1=22.71 cm−1; J2=J3=0.34 cm−1 and g=2.10. The magnetic results are interpreted with structural parameters.

Two novel polymeric networks of cadmium(II), [Cd2(ibn)(SeCN)4]n (1) (ibn=1,2-diamino-2-methylpropane) and [Cd(pyz)(SeCN)2]n (2) (pyz=pyrazine) have been synthesised and their molecular structures have been determined by X-ray crystallography. The polymer 1 consists of two 1D parallel chains of Cd(II), each having alternate tetrahedral (CdSe4) and octahedral (CdN6) Cd(II) centres bridged through selenocyanate, exhibiting symbiotic phenomena. The octahedral Cd(II) centre of one chain is linked with the tetrahedral Cd(II) centre of another chain through selenocyanate ligand resulting 1D ladder like structure. The complex 2 is a 2D network of octahedral Cd(II) (CdN4Se2) in which doubly selenocyanato bridged 1D coordination polymeric chains are linked through pyrazine ligand in a bc plane forming rectangular grid like structure.