title: Crystal Structures and Magnetic Properties of CuX(2)(pdmp)(2) Complexes (X = Br, Cl).
abstract: We report the synthesis and the structural and magnetic characterization of two new compounds: dibromobis(pdmp)copper(II), CuBr(2)C(22)H(24)N(4) (1), and dichlorobis(pdmp)copper(II), CuCl(2)C(22)H(24)N(4) (2), where pdmp = 1-phenyl-3,5-dimethylpyrazole. The structures were refined by full-matrix least-squares techniques to R1 = 0.0620 and 0.0777, respectively. Compound 1 belongs to the space group P2(1)/n with a = 8.165(5) Å, b = 10.432(3) Å, c = 13.385(4) Å, beta = 100.12(4) degrees, and Z = 2. Compound 2 belongs to the space group P2(1)/c with a = 8.379(2) Å, b = 22.630(2) Å, c = 12.256(2) Å, beta = 98.43(3) degrees, and Z = 4. It has the same molecular formula as a compound reported previously but a different crystal structure. Detailed single-crystal EPR measurements were performed for single-crystal samples of 1 and 2 at 9 and 35 GHz and at room temperature. The positions and line widths of the EPR lines were measured as a function of the magnetic field orientation in three orthogonal planes. The data were used to study the electronic properties of the copper ions and to evaluate the exchange interactions between them. Our results are discussed in terms of the electronic pathways for superexchange between copper ions, which are provided by the stacking of pyrazole and phenyl rings of neighboring molecules and by hydrogen-halogen bonds.
authors.affiliation: Instituto de Física de São Carlos, Universidade de São Paulo, CP 369, 13560-970 São Carlos, SP, Brazil, Instituto de Química de Araraquara, UNESP, CP 174, 14800 Araraquara, SP, Brazil, and Facultad de Bioquímica y Ciencias Biológicas, Universidad Nacional del Litoral and INTEC (CONICET-UNL), Güemes 3450, 3000 Santa Fe, Argentina.
authors.forename: Antonio J.
authors.initials: AJ
authors.lastname: Costa-Filho
authors.forename: Claudia E.
authors.initials: CE
authors.lastname: Munte
authors.forename: Claudio
authors.initials: C
authors.lastname: Barberato
authors.forename: Eduardo E.
authors.initials: EE
authors.lastname: Castellano
authors.forename: M. P. D.
authors.initials: MP
authors.lastname: Mattioli
authors.forename: Rafael
authors.initials: R
authors.lastname: Calvo
authors.forename: Otaciro R.
authors.initials: OR
authors.lastname: Nascimento