Comparison between d1-d1 and d9-d9 magnetic exchange in binuclear vanadyl and copper(II) 1,3,5-triketonates. Crystal and molecular structure of Cu2(DANA)2(py)2

Article abstract of DOI:10.1021/ic50217a040

The binuclear complex bis(1,5-bis(p-methoxyphenyl)-1,3,5-pentanetrionato)bis(pyridine)dicopper(II), Cu₂(DANA)₂(py)₂, has been crystallized and examined by X-ray diffraction techniques. The structure consists of binuclear monomers in which each copper atom is bound to four ketonic oxygen atoms and an axial pyridine. Crystal data is as follows: P2₁/c, a = 8.413 (2) ?, b = 22.791 (5) ?, c = 11.109 (2) ?, β = 91.60 (2)°, Z = 2, R₁ = 0.035, R₂ = 0.050. The d⁹-d⁹ system, Cu₂(DANA)₂(py)₂, exhibits strong intramolecular antiferromagnetism (-2J = 825 cm^-1) resulting in nearly diamagnetic behavior at room temperature. These results are contrasted to the structurally related d¹-d¹ system, (VO)₂(DANA)₂, in which the value of -2J is 160 cm^-1. The magnetic differences are discussed in terms of the orbital symmetry of the exchanging electrons.