Synthesis and X-ray structures of a series of heteroleptic selenites of copper.

The reactions of [Cu(R-pySe)], R = H, 3-CF(3), with 2,2'-bipyridine or 1,10-phenanthroline in acetonitrile yielded the one-dimensional complexes {[Cu(SeO(3))(phen)] x 2 (H(2)O)}(n), 1, {[Cu(SeO(3))(bipy)] x 2 (H(2)O)}(n), 2. Recrystallization of 1 and 2 from a 1:1 methanol/water mixture led to the formation of the dinuclear complexes Cu(SeO(3))(phen)(H(2)O), 3, and Cu(SeO(3))(bipy)(H(2)O), 4. Single crystal X-ray diffraction analysis revealed that 1 and 2 have a polymeric structure in which each oxygen atom of the selenite group coordinates to a copper atom. The two other coordination positions are occupied by two nitrogen atoms of the organic ligand, and this defines an almost square pyramidal geometry around the metal. Both compounds show a very weak antiferromagnetic coupling (J = -0.9 for 1 and -0.6 cm(-1) for 2). Compounds 3 and 4 consist of dinuclear species with the copper atoms lying in a square pyramidal geometry in which the selenite group acts as a bridge between two copper atoms and one oxygen atom is uncoordinated. The two copper ions in 3 show antiferromagnetic coupling with J = -22.1 cm(-1).