A series of fascinating diiron complexes featuring bridging N(x)H(y) ligands stabilized by tris(phosphine)borate ([PhB(CH(2)PR(2))(3)] = [PhBP(R)(3)]) ligands have been characterized. Hydrazine activation by [PhBP(R)(3)]Fe-Me (R = Ph or cyclohexylmethyl) leads to diiron Fe(2)(mu-eta(1):eta(1)-N(2)H(4))(mu-eta(2):eta(2)-N(2)H(2)) complexes featuring both bridging hydrazine and hydrazido ligands....