Synthesis, crystal structure and magnetic properties of dinuclear manganese(II) diketonate with cyanopyridine-N-oxide bridging ligands [Mn(hfac)2(4-cpyNO)]2

The reaction of Mn(hfac)(2) (.) 2H(2)O (hfac, hexafluoroacetylacetonate anion) with 4-cpyNO (4-cyanopyridine-N-oxide) in chloroform results in the formation of a novel mixed-ligand complex [Mn(hfac)(2)(4-cpyNO)](2). X-ray single crystal structure revealed the presence of dinuclear molecules [Mn(hfac)(2)(4-cpyNO)](2). Within the dimer, two manganese(II) ions are in an octahedral environment and are bridged by two 4-cpyNO ligands through oxygen atoms of the N-oxide groups. The magnetic properties of the compound were studied in the temperature range of 2-300 K. The interaction between Mn(II) ions was found to be weakly ferromagnetic with an exchange coupling constant J = 0.23 cm(-1) in contrast to an antiferromagnetic interaction observed for most compounds with the Mn(II)(mu-O)(2)Mn(II) bridging core. Some magneto-structural correlations are discussed. (C) 2003 Elsevier Ltd. All rights reserved.