A bridging hexazene (RNNNNNNR) ligand from reductive coupling of azides

This communication reports the first examples of transition metal complexes containing an RNNNNNNR(2-) ligand. Addition of 1-azidoadamantane to the diiron(l) synthon L(R)FeNNFeL(R) (L(R) = HC[C(R)N(2,6-iPr(2)C(6)H(3))](2); R methyl, tert-butyl) leads to the diiron complexes L(R)Fe(mu-eta(2):eta(2)-AdN(6)Ad)FeL(R), which are surprisingly thermally stable. Magnetic, Mossbauer, and crystallographic data are consistent with pairs of high-spin iron(II) ions antiferromagnetically coupled through a dianionic AdN(6)Ad(2-) bridge.