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Reaction of 2-amino-5-trifluoromethylpyridine (5-TFMAP) with copper halides in water or alcohol solvents produced four coordination complexes: (5-TFMAP) 2 CuX 2 , (X = Cl ( 1 ) or Br ( 2 )), (5-TFMAP) 3 CuBr 2 ( 3 ) and [(5-TFMAP) 2 CuBr 2 ](5-TFMAPH)Br ( 4 ). In all compounds, the 5-TFMAP ligands are coordinated to the Cu(II) ion through the pyridine nitrogen atom in a trans -geometry and a nearly square planar environment is observed in 1 , 2 and 4 . In 3 , coordination of an additional 5-TFMAP ligand results in a distorted trigonal bipyramidal complex. All complexes are characterized by single-crystal X-ray diffraction. Compound 1 crystalizes as a chain structure via pairs of long Cl…Cu contacts between molecules and the temperature dependent magnetic susceptibility data has been fit to an alternating chain model, resulting in J = −5.97(1) K and J ′ = −0.95(4) K. Compound 2 exhibits weaker antiferromagnetic interactions, also via the bihalide superexchange pathway, resulting in J = −3.02(2) K from a fit to the uniform chain model. The structure of compound 3 also exhibits a uniform antiferromagnetic chain, but via the two-halide pathway (short Br…Br contacts) and susceptibility data exhibit significantly stronger interactions ( J = −31.05(5) K). Compound 4 is not stable in air and loses a molecule of 5-TFMAP from the crystal lattice upon standing. [ABSTRACT FROM AUTHOR]

Abstract: Reaction of 2-amino-5-trifluoromethylpyridine (5TFAP) with copper halides in aqueous acid gives rise to the salts (5TFAPH)2CuX4 [X=Cl (1), Br (2)] which were characterized by IR, combustion analysis, single-crystal X-ray diffraction and variable temperature magnetic susceptibility. The complexes crystallize in the triclinic space group , but are not isostructural. The chloride salt 1 forms an S=½ magnetic ladder via a combination of bihalide (rungs) and two-halide (rails) bridges. The ladders are well isolated by the 5TFAPH cations. A fit of the magnetic susceptibility data (T =1.8–310K) agreed well with the strong-rung ladder model, yielding C=0.384(4)emu-K/mol-Oe, J rung =−13.9(1)K and J rail =−2.90(4)K. Compound 2 exhibits tetrabromocuprate ions which are bridged into a distorted honeycomb structure, but with short Br…Br contacts between the layers. Magnetic data indicate only very weak antiferromagnetic exchange in spite of Br…Br contacts as short as 3.8Å. [Copyright &y& Elsevier]