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A novel family of homodinuclear complexes of the general formula [Ln2L2(X)2] (where Ln = Nd3+, Pr3+, Sm3+and Tb3+for 1, 2, 3and 4, respectively and X, the coordinated NO3−or Cl−anion) has been synthesised from the corresponding lanthanide(III) salts with the pentadentate dianionic Schiff base ligand, H2L [N1,N3-bis(salicylideneimino)diethylenetriamine], that exhibits a N3O2donor set. Single crystal X-ray diffraction studies evidenced the isostructurality of this family of centrosymmetric neutral dinuclear entities where the Ln(III) metal centres are coupled together by two phenolato oxygen atoms belonging to two units of ligand (H2L). Interestingly, the two other phenolato groups of H2L are mono-coordinated to the metal ions. Temperature dependence (2-300K) magnetic susceptibility studies suggest the presence of an antiferromagnetic interaction operating viadouble phenolato bridges. Photoluminescence activities of the complexes have been studied and compared with their precursor ligand. All the complexes have been characterised with microanalytical and several spectroscopic techniques. [ABSTRACT FROM AUTHOR]

A new NaI/CuI–IIheterometallic coordination complex [Cu2L2Na(NCO)2Cu]n(1) with an unusual architecture has been synthesised. In 1cyclic Na-O-Cu-O-Cu cages constructed by the tetradentate N2O2donor Schiff base ligand (H2L = N,N′-bis(2-hydroxyacetophenone)propylenediimine) are interconnected to each other by a rare singly end-to-endbridged OCN-Cu(I)-NCO link generating 1D chain. The complex has been characterised by elemental, spectral and structural analysis. The cyclic voltammogram of 1has been compared with the analogous complexes. Cryomagnetic susceptibility studies indicate the copper(II) centers in the cyclic Na-O-Cu-O-Cu cages are antiferromagnetically coupled with J= −13.8 cm−1. Complex 1is a new addition to a class of rare singly end-to-endcyanato bridged copper(I) species and interestingly the copper ions involved in OCN-Cu(I)-NCO links possess a linear 2-coordinate geometry. Density functional theory calculations have been carried out to gain additional insights into the metal and ligand orbitals participating in this unusual structure. [ABSTRACT FROM AUTHOR]

Abstract  A nickel(II) and a cobalt(III) complex of two different potentially tetradentate Schiff bases with different binding modes have been synthesised. The nickel(II) complex [NiL1] · CH3OH (1) was formed, on reacting the metal salt with a perfectly symmetrical N2O2 tetradentate Schiff base ligand H 2 L 1 , which is the 1:2 condensation product of 1,3-diamino propane and 2-hydroxyacetophenone. The cobalt(III) complex [Co(HL2)3] · (ClO4)3 · H2O (2) was synthesised using an asymmetric N2O2 tetradentate Schiff base ligand HL 2 on condensing N,N-dimethyl-1,3-diamino propane with o-vanillin in 1:1 mmol ratio. Although both Schiff bases are N2O2 functionalised, they showed variation in their coordinative property with nickel(II) and cobalt(III) ions. Both the complexes were characterised by IR spectroscopy and cyclic voltammetry and their single crystal structures clearly indicate that 1 is a mononuclear species whereas 2 is a hydrogen-bonded dimer. [ABSTRACT FROM AUTHOR]

Abstract  Three new coordination complexes of Zn(II) and Mn(II) have been synthesised using two different tridentate N,N,O donor hydrazone ligands, Hpbh and Hacpbh respectively. The complexes [Zn(pbh)2] (1) and [Zn(acpbh)2] (2) have been synthesized by the treatment of ZnSO4 · 7H2O with Hpbh and Hacpbh hydrazone ligands, respectively. The Mn(II) complex [Mn(acpbh)2] (3) was obtained on reacting Mn(NO3)2 · 4H2O with the ligand Hacpbh. The ligands Hpbh and Hacpbh were prepared by condensing pyridine-2-carboxaldehyde and 2-acetylpyridine with benzhydrazide respectively. Inspite of varying the carbonyl functionality attached to the pyridine moiety present in the hydrazone ligands in both the Schiff bases, we obtained three mononuclear complexes 1, 2, and 3 which were clearly characterized from single crystal X-ray diffraction studies. Spectroscopic investigations like IR and UV/Vis have been carried out for 1, 2, and 3. Fluorescence studies have been performed for 1 and 2. For 3 cyclic voltammetry, room temperature magnetic study and EPR measurements have been recorded. [ABSTRACT FROM AUTHOR]