Electron paramagnetic resonance study of ternary CuII compounds with glycine and phenanthroline

被引:3
作者
Santana, Ricardo C. [1 ]
Araujo, Anderson B. C. [1 ]
Carvalho, Jesiel F. [1 ]
Calvo, Rafael [2 ,3 ]
机构
[1] Univ Fed Goias, Inst Fis, BR-74001970 Goiania, Go, Brazil
[2] Univ Nacl Litoral, Fac Bioquim & Ciencias Biol, Dept Fis, RA-3000 Santa Fe, Argentina
[3] UNL, CONICET, Inst Fis Litoral, RA-3000 Santa Fe, Argentina
关键词
Ternary copper compounds; glycine; phenanthroline; EPR; magnetic interactions; SINGLE-CRYSTAL EPR; CATION-PI INTERACTIONS; AMINO-ACID SALTS; MAGNETIC-PROPERTIES; EXCHANGE INTERACTIONS; COPPER(II) COMPLEX; MOLECULAR-STRUCTURE; UNPAIRED SPINS; CARBOXYLATE; 1,10-PHENANTHROLINE;
D O I
10.1007/s12039-013-0553-0
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
We report here electron paramagnetic resonance (EPR) measurements at 9 and 34 GHz, and room temperature (T), in powder and single crystal samples of the ternary compounds of copper nitrate or copper chloride with glycine and 1,10-phenanthroline [Cu(Gly)(phen)(H2O)]center dot NO3 center dot 1.5H(2)O (1) and [Cu(Gly)(phen)Cl](2)center dot 7H(2)O (2). In compound 1, the copper ions are arranged in 1-D chains along one of the crystal axes connected by syn-anti carboxylate ligands, while in 2 the array is nearly 3-D and the connections involve H-bonds and stacking interactions. The angular variation of the squared g-factor and the line width were measured as a function of orientation of the magnetic field (B-0) in three orthogonal crystal planes. In both compounds we observed one resonance without hyperfine structure for any magnetic field orientation which we attribute to the collapse of the hyperfine coupling and of the resonances of two chemically identical but rotated coppers in the unit cell, produced by exchange interactions. We analyse the results in terms of the structures of the compounds and chemical paths connecting neighbour copper ions which support the exchange interactions between neighbour spins in the lattice. Considering the collapse of the EPR signals of rotated sites in the lattices we are able to set lower limits to the exchange interactions, which are supported by weak equatorial-apical carboxylate bridges in 1, and by paths containing hydrogen bonds and aromatic pi-pi interactions in 2. Broadening due to dipole-dipole couplings and hyperfine interactions are strongly reduced by these exchange couplings and their role in the EPR line width is more difficult to recognize.
引用
收藏
页码:255 / 264
页数:10
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