Synthesis and magnetic properties of binuclear copper(II) complexes with alkoxide bridges

Abstract

Five binuclear Cu II complexes [Cu 2L(μ-N 3)](ClO 4) 2 · 1 2 C 2H 5OH · 2H 2O ( 1), [Cu 2L(μ-C 7H 5O) 2](ClO 4) 2 ( 2), [Cu 2L(μ-C 3N 2H) 3](ClO 4) 2 · 3 2 C 2H 5OH ( 3, [Cu 2L(μ-Br)]Br 2 · H 2O ( 4), [Cu 2L(μ-OH)](ClO 4) 2 · 3H 2O ( 5) were synthesized (where HL are 1:2 Schiff bases derived from 1,3-diamino-2-hydroxypropane and picolinaldehyde N-oxide). Based on the IR spectra, elemental analyses and conductivity measurements, these complexes are proposed to have an endogenous bridge (alkoxide) and an exogenous bridge (it may be an anion). The complexes were characterized by variable temperature magnetic susceptibility (4–300 K) and the data were fitted by least-squares to a susceptibility equation derived from the spin Hamiltonian, H = −2 JS 1 · S 2. The exchange integral J was found to be −321.5 cm −1 for 1, −95.3 cm −1 for 2, −26.5 cm −1 ( 3), −5.6 cm −1 ( 4) and −5.5 cm −1 ( 5). It was observed that − J decreases in the order N 3 − > −O 2CC 6H 5 > Im − > OH − ≈ Br −.