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Four new copper(II) compounds with an inorganic, adamantane-like core have been prepared and structurally characterized: [(2-aminopyridine)4(μ2-Br)6Cu4(μ4-O)].(2-aminopyridinium) bromide monohydrate (1), the open cage structure (2-aminopyridinium) [(2-aminopyridine)4(μ2-Cl)5(Cl)2Cu4(μ4-O)] (2), bis(2-amino-5-methylpyridinium) [(2-amino-5-methylpyridine)2(μ2-Cl)6(Cl)2Cu4(μ4-O)] (3) and the co-crystal [(2-amino-5-fluoropyridine)4(μ-Cl)6Cu4(μ4-O)]2 [(2-amino-5-fluoropyridine)4Cu2Cl4] (4). All four include additional components in the lattice ranging from a non-coordinated ancillary ligand (1) to a co-crystallization with a distinct coordination complex (4). The compounds crystallize as: 1, triclinic, P-1; 2, monoclinic, P21/c; 3, monoclinic, P21/c; 4, triclinic, P-1. Analysis of the geometric parameters within the adamantoid cores of the compounds indicates significant structural resilience as parameters are little changed by the presence of additional components in the lattice. Breaking of the central core by coordination of an additional chloride ion in 2 significantly affects the geometry about those two Cu(II) ions but has little effect on other parts of the core. [ABSTRACT FROM AUTHOR]

Three new copper(II) complexes with the general formula Cu4X6O(L)4 (1, X = chloride, L = 2-amino-5-chloropyridine; 2, X = chloride, L = 2-amino-5-bromopyridine and 3, X = bromide, L= 2-aminopyridine) with an adamantane-like core structure are reported. 1 and 2 crystallize in the space group P-1, while 3 crystallizes in the space group P21/c. We also report comparisons between the structures of these compounds and ones found in a literature review of compounds with similar structures and organic ligands. The members of this family all exhibit antiferromagnetic interactions and the possibility of magnetic frustration due to their geometries. [ABSTRACT FROM AUTHOR]

Two new coordination polymers, [Cu(pz)(L)2(H2O)2](ClO4)2 (L = 2-Cl- (1) or 2-Br-4-pyridone (2); pz = pyrazine), have been synthesized and characterized by X-ray diffraction, EPR and variable temperature magnetic measurements. Both compounds crystallize as well isolated pyrazine-bridged chains with the heterocyclic ligands in the pyridone tautomer and coordinated via the oxygen atom. The Cu ions possess Jahn-Teller elongated octahedral geometries with the Jahn-Teller axis along the Cu-O axis. The water molecules in 2 are inequivalent with one molecule semi-coordinate (dCu...O = 3.225(6) Å) at an occupancy of 0.72. Both compounds exhibited axial powder EPR spectra, as expected. Variable temperature magnetic measurements are well fit by the uniform chain Heisenberg antiferromagnetic model with J = −10.74(4) K (1) or = −10.64(2) K (2). Comparison with the known 3-halo-4-pyridone compounds suggests an inverse relationship between the Cu-pz-Cu distance and the strength of the magnetic exchange. [ABSTRACT FROM AUTHOR]

Bis(bidentate) and bis(tridentate) Co(III) complexes of N-(2-hydroxyethyl)ethane-1,2-diamine (heen), 2-[(2-aminoethyl)amino]ethan-1-olate (heen-H), or N-(2-chloroethyl)ethane-1,2-diamine (ceen) ligands have been synthesised, and a range of reaction conditions established for their syntheses by different routes. They can all be ultimately derived from (OC-6-12′)-[Co(heen)2(NO2)2]NO3 and provide access to the trans amine trans chloride nitrogen mustard complex, (OC-6-12′)-[Co(ceen)2(Cl)2]Cl. Although complex isomeric mixtures were obtained from the reaction of (OC-6-12′)-[Co(heen)2(NO2)2]NO3 under different reaction conditions, ultimately, the trans amine trans chlorido configuration around the Co(III) metal centre of the (OC-6-12′)-[Co(ceen)2(Cl)2]Cl complex was favoured. [ABSTRACT FROM AUTHOR]

The reaction of Cu[Cl.sub.2] with 2-amino-5-fluoropyridine and HCl in aqueous solution has produced bis(2-amino-5-fluoropyridinium)tetrachlorocuprate(II). The first-principles bottom-up studies have shown that at low temperature the crystal complex has a three-dimensional magnetic topology and a singlet ground state.

Reaction of copper(II) perchlorate with pyrazine and pyridine-N-oxide produced the coordination polymer catena-[diaqua-μ-pyrazine-bis(pyridine-N-oxide)copper(II)] perchlorate (1) which was characterized by single-crystal X-ray diffraction, EPR and variable temperature magnetic susceptibility measurements. The compound forms well-isolated linear chains, bridged by pyrazine. EPR studies show a rhombic structure with gave = 2.15. The magnetic data are well described by the uniform Heisenberg chain model giving J/kB = −9.6(1) K and show no signs of inter-chain interactions down to 1.8 K [H = −JΣS1S2]. In the course of the synthesis, the related [tetrakis(pyridine-N-oxide)copper(II)] perchlorate complex (2) was also isolated. X-Ray studies confirm the identity of the compound in comparison to the previous literature. EPR studies indicate a rhombic structure, similar to 1, but variable temperature magnetic susceptibility data show no significant magnetic exchange in agreement with the absence of a superexchange pathway in the crystal. [ABSTRACT FROM AUTHOR]