Synthesis and magnetostructural characterization of two ferromagnetic nickel(II) dimers

Two new ferromagnetic, end-on azide-bridged nickel(II)-dimers [{Ni(terpy)(N -3)(2)}(2)]. H2O 1 and [Ni-2(terpy)(2)(N-3)(3)(H2O)]ClO4. H2O 2 (terpy = 2, 2' : 6',2 "-terpyridine) have been synthesized and magnetostructurally char acterized through X-Ray single crystal analysis, IR spectroscopy and magnet ic susceptibility measurements. The values of the Ni-N-Ni bridge angle and the magnetic coupling constant, J, are 101.6 degrees and 22.8 cm(-1), respe ctively, for 1 and 102.5 degrees and 13.6 cm(-1), respectively, for 2. The influence of the Ni-N-Ni bridge angle on the magnetic performance of end-on azide-bridged nickel(II) dimers has been studied by means of extended Huck el molecular orbital calculations. The results indicate that the antiferrom agnetic contribution of the global coupling constant decreases for increasi ng bridge angle between 83 and 115 degrees.