Synthesis, Structural Characterization, and Magnetic Properties of the Heteroleptic Dinuclear Nickel Selenite Complex [{Ni(TMEDA)SeO3}2]

The reaction of Ni(NO3)(2)center dot 6H(2)O with Na2SeO3 in the presence of tetramethylethylenediamine (TMEDA) in a water/ethanol mixture yielded the heteroleptic complex [{Ni(TMEDA)SeO3}(2)] (1). Single-crystal X-ray diffraction analysis showed that complex 1 consists of a dinuclear species in which the two nickel atoms are held together by two bridging selenito anions. The crystal packing of 1 is determined by networks of hydrogen bonds, involving cocrystalized water molecules and the oxygen atoms of the bridging SeO32- groups. The two nickel ions in 1 exhibit antiferromagnetic coupling with J = -25.7 +/- 0.1 cm(-1), in good agreement with DFT calculations. In addition, when a less sterically hindered ancillary ligand, such as ethylenediamine (en), was used, the homoleptic complex [Ni(en)(3)](SeO3) (2) was obtained.