Synthesis, characterization and magnetism of μ‐chloranilato binuclear chromium (III) complexes

Abstract

Abstract Five new chloranilato‐bridged binuclear chromium (III) complexes have been synthesized and Identified as [Cr 2 (CA)L 4 ]‐(ClO 4 ) 4 [L denotes 5‐methyl‐1,10‐phenanthroline (Me‐phen); 2,9‐dimethyl‐1,10‐phenanthroline (Me 2 ‐phen); 5‐chloro‐1,‐10‐phenanthroline (Cl‐phen); diaminoethane (en) or 1,3‐diaminopropane (pn)], where CA represents the dianion of chloranilic acid. Based on elemental analyses, molar conductivity and magnetic moment of room‐temperature measurements, and IR and electronic spectral studies, it is proposed that these complexes have CA‐bridged structures and consist of two chromium (III) ions, each in an octahedral environment. The complexes [Cr 2 (CA)(Me‐phen) 4 ](ClO 4 )4(1) and [Cr 2 (CA)(Me 2 ‐phen) 4 ](CIO 4 )4(2) were further characterized by variable temperature (4.2–300 K) magnetic susceptibility measurements and the observed data were successfully simulated by the equation based on the spin Hamiltonian operator, Ĥ = ‐2 JŠ 1 · Ŝ 2 , giving the exchange parameter J = ‐7.8 cm −1 for (1) and J = ‐6.5 cm 1 for (2). This result indicates that there is weak ant ferromagnetic spin‐exchange interaction between the two chromium (III) ions within each molecule.