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Formation, Structures, and Magnetic and EPR Spectroscopic Properties of Dicobalt(III)‐Dicopper(II) Complexes Featuring Heterotetranuclear Cations of a Puckered Cyclic Structure with Diethanolamine and Diethanolamine(2−) as Bridging Ligands
Author(s) -
Makhankova Valeriya G.,
Vassilyeva Olga Yu.,
Kokozay Volodymyr N.,
Reedijk Jan,
Albada Gerard A. van,
Jezierska Julia,
Skelton Brian W.
Publication year - 2002
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/1099-0682(200208)2002:8<2163::aid-ejic2163>3.0.co;2-4
Subject(s) - chemistry , crystallography , electron paramagnetic resonance , diethanolamine , octahedron , cobalt , copper , intramolecular force , molecule , magnetic susceptibility , square pyramidal molecular geometry , hydrogen bond , crystal structure , inorganic chemistry , stereochemistry , nuclear magnetic resonance , physics , organic chemistry
The compounds [Cu II 2 Co III 2 (H 2 dea) 2 (dea) 4 ]X 2 (Solv) n [X = Cl ( 1 ), Br ( 2 ), SCN ( 3 ), O 2 CMe ( 4 ), I ( 5 ); Solv = H 2 O or/and CH 3 OH, DMF, n = 1−4] were synthesised by the reaction of zero‐valent copper with cobalt(II) salts in non‐aqueous (CH 3 OH, DMF, DMSO) solutions of diethanolamine (H 2 dea) in air. Crystallographic investigations of 1 − 4 reveal that the complexes contain the centrosymmetric cation [Cu 2 Co 2 (H 2 dea) 2 (dea) 4 ] 2+ in which the four metal atoms are linked together by bridging oxygen atoms of the six ligand groups to form a parallelogram with the length of the short edge (Cu ··· Co) being ca. 2.83 Å and a short diagonal distance (Cu ··· Cu) at approximately 3.23−3.29 Å. The copper atom is five‐coordinate with a square‐pyramidal geometry; the geometry at the trivalent cobalt ion is almost octahedral. The tetranuclear units are further stabilized by intramolecular O−H ··· O and N−H ··· O hydrogen bonds. The hydrogen‐bonded network that involves the OH and NH groups of the ligands, uncoordinated anions, and solvent molecules links the tetranuclear units together and results in the formation of extended two‐ and three‐dimensional networks. Variable‐temperature magnetic susceptibility measurements of 1 − 3 and 5 show no significant exchange coupling between the copper centres. The frozen‐solution and solid‐state EPR spectra at 77 K are characteristic of a triplet state with the hyperfine structure distinctly resolved in solution. On the assumption of noncoaxiality of the g and D tensors the spectra were interpreted with the zero‐field‐splitting parameters D = 0.0560(1) ( 2 − 5 ) and D = 0.0712(1), E = 0.0028(2) cm −1 ( 1 ). Dominant contributions to the observed EPR zero‐field splitting are presumed to be dipole‐dipole in origin. (© Wiley‐VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)