An Azide-Bridged Copper(II) Ferromagnetic Chain Compound Exhibiting Metamagnetic Behavior

The one-dimensional chain complex [Cu(2)((2)-1,1-N(3))(2)((2)-1,3-NO(3))(2)((2)-1,3-Me(3)NCH(2)CO(2))(2)](n)() (1) contains three different bridge groups, (2)-1,1-azide (end-on), (2)-nitrate, and (2)-syn,syn-carboxylate, arranged so that the azide and carboxylate groups bridge equatorially and dictate the intrachain magnetic behavior between the copper magnetic orbitals. Variable-temperature magnetic susceptibility studies at low field, and magnetization studies at variable field, reveal dominant intrachain ferromagnetism (J = 26 cm(-)(1)) but also much weaker interchain ferromagnetism ( = 2.3 K) and antiferromagnetism (J(eff) = -0.18 cm(-)(1)). The structure has been rationalized in terms of a layered magnetic model with antiferromagnetic coupling between ferromagnetically coupled layers, leading to metamagnetic behavior. The intrachain ferromagnetism is explained satisfactorily using extended Hückel molecular orbital calculations, which show clearly that orbital countercomplementarity exists on the part of the two magnetic bridge groups (azide and carboxylate), despite the very large azide bridge angle (119.5 degrees ).