6533b85ffe1ef96bd12c0fd2

RESEARCH PRODUCT

Intramolecular versus intermolecular exchange pathways in the binuclear complex [Cu2(H2tea)2(4,4′-bipy)](ClO4)2·3H2O (H3tea=triethanolamine and 4,4′-bipy=4,4′-bipyridine)

subject

description

Abstract The binuclear copper(II) complex of formula [Cu2(H2tea)2(4,4′-bipy)](ClO4)2·3H2O (1) (H3tea=triethanolamine and 4,4′-bipy=4,4′-bipyridine) has been isolated and characterized by X-ray diffraction. Its structure consists of dinuclear [Cu2(H2tea)2(4,4′-bipy)]2+ cations, uncoordinated perchlorate anions and crystallization water molecules. Each copper atom exhibits a trigonal-bipyramidal environment with the three triethanolamine-oxygen atoms building the equatorial plane, and the triethanolamine-nitrogen and one of the 4,4′-bipy nitrogen atoms defining the three-fold axis. The 4,4′-bipy molecule acts as a bismonodentate bridging ligand, the copper–copper separation across it being 11.068(2) A, a value which is much longer that the shorter intermolecular one (4.821(1) A) through the pathway Cu(1)O(2)⋯O(3A)iCu(1)i, with (i)=−x+1, −y+1, −z+1. Variable-temperature magnetic susceptibility measurements in the temperature range 1.9–290 K reveals the occurrence of a weak but significant intermolecular antiferromagnetic interaction (J=−5.0 cm−1) between the copper(II) ions belonging to two neighboring binuclear units (the Hamiltonian being H=−JS1·S2). The intramolecular copper–copper exchange interaction across the 4,4′-bipy bridge is assumed to be extremely weak (J≈−0.1 cm−1).