Structure and Magnetic Behavior of a New 1-D Compound with Simultaneous End-On Azido and Carboxylato Bridges. Unexpected Strong Ferromagnetic Coupling for a Cu-N-Cu Bond Angle of 111.9 degrees as a Consequence of Ligand HOMOs Countercomplementarity.

The X-ray structure of the &mgr;-carboxylate-&mgr;(1,1)-azido-bridged compound {[Cu(Hpht)(N(3))].H(2)O}(n)() has been determined (Hpht = hydrogen phthalate). Crystal data: formula C(8)H(7)CuN(3)O(5), monoclinic, P2(1)/m (No. 11), a = 7.383(3) Å, b = 6.568(4) Å, c = 10.659(4) Å, beta = 93.38(3) degrees, Z = 2. The compound is found to be a system formed by chains of copper atoms bridged simultaneously by syn-syn carboxylato and end-on azido bridges. The copper chains are linked by a second carboxylato bridge, giving a 2-D compound. Magnetic measurements indicate strong ferromagnetic coupling, which affords a good example of unexpected magnetic properties due to the countercomplementarity of the superexchange pathways of the two ligands.