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Three new heterobimetallic 1D coordination polymers have been obtained by assembling the [Ni(bpca)2] complex, as a building block, with lanthanide cations: [{Ln(O2NO)(H2O)3}{Ni(bpca)2}](NO3)2·3H2O (Ln Gd 1; Tb 2; Dy 3). The three compounds are isostructural and their structure consists of infinite cationic chains with LnIII ions connected by [Ni(bpca)2] complexes acting as bridging bis-bidentate ligands. The charge of the chains is counterbalanced by uncoordinated nitrate ions. The LnIII ions display a coordination number of nine: four oxygen atoms from the carbonyl groups of the bpca ligands belonging to two {Ni(bpca)2} moieties, two oxygen atoms from a chelating nitrato ion and three water molecules. The magnetic investigation of the gadolinium derivative 1 revealed very weak intrachain NiII–GdIII-ferromagnetic interactions (θ = +0.15 K). The weak intrachain-exchange interactions, as well as the bad magnetic isolation of the chains in the crystals, preclude the single-chain magnet behaviour of compounds 2 and 3. The out-of-phase, χ″, signal observed with compounds 2 and 3 can be ascribed to the magnetic slow relaxation of the lanthanide ions (TbIII, DyIII).(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Ditopic bis(acylhydrazone) ligands, derived from the reactions of carbohydrazides with 2-phenylpyrimidine-4,6-dicarbaldehyde and designed for grid formation with octahedrally coordinating transition-metal ions, exhibit a varied coordination chemistry depending upon the degree of their deprotonation. The neutral acylhydrazones are relatively poor ligands and are seemingly involved in multiple, labile complexation equilibria varying with the solvent and the particular metal salt in solution; nevertheless, grid complexes of different forms can be isolated in the solid state. Although only limited study has been made of the singly deprotonated ligands, grid species appear to be much more readily isolated. With the doubly deprotonated ligands, grid formation is strongly favoured in both the solution and solid states. As a consequence, the grid structures form spontaneously in the presence of a base by self-assembly from their components without need to preform the ditopic ligands. Extensive structural studies have been carried out both to establish the grid structures and to analyse the nature of the supramolecular interactions possible for neutral and charged grid species. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

The reaction between [Mn(MAC)(H2O)2]Cl2·4H2O and LiTCNQ (MAC = 2,13-dimethyl-3,6,9,12,18-pentaazabicyclo[12.3.1]octadeca-1(18),2,12,14,16-pentaene) affords a complex with the formula [Mn(MAC)(TCNQ)2] (1), whose crystal structure has been determined. Its structure consists of neutral mononuclear entities. The manganese(II) ion is heptacoordinated, with a pentagonal bipyramidal geometry. The apical positions are occupied by the TCNQ·− radicals, while the macrocyclic ligand is coordinated at the equatorial positions. The seven Mn−N distances range from 2.273(3) to 2.301(6) A. The strong intermolecular π−π stacking interactions between the TCNQ radicals (3.2 A) leads to weave-like infinite chains, which propagate along the crystallographic c axis. The cryomagnetic investigation of 1 revealed a weak intermolecular antiferromagnetic coupling of the Mn2+ ions (J = −0.18 cm−1), which is mediated by the diamagnetic (TCNQ)22− pairs resulting from the stacking interactions in the crystal. The intermolecular exchange interaction between the Mn2+ ions was further confirmed by variable temperature EPR spectroscopic measurements [|J| = 0.15(5) cm−1], which have been carried out in both the X and Q bands. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)