The organohydrazide chelate complexes M(III)(NNpy)(PPh(3))(2)Cl(2) (1, 3) (M = Re, Tc) have been synthesized using the organohydrazine 2-hydrazinopyridine. The chelated organohydrazide is a diazenido(1-) ligand that forms a five-membered ring with the metal center. An X-ray structural analysis of 1 indicates that there is a delocalized pi-system formed by the chelate ring. These octahedral, d(4) metal complexes have diamagnetic (1)H NMR spectra. Complex 1, C(41.50)H(34)Cl(2)N(3)O(0.5)P(2)Re, crystallizes in the triclinic space group P&onemacr; with a = 10.5549(7) Å, b = 12.2699(8) Å, c = 16.8206(12) Å, alpha = 105.9050(10) degrees, beta = 95.8930(10) degrees, gamma = 111.0100(10) degrees, V = 1906.1(2) Å(3), Z = 2, and R = 0.0650 based on 5268 unique reflections. The FABMS+ in (p-nitrobenzyl alcohol) of 3 reveals a parent ion peak at m/z 799.2. The complex [Re(HNNpy)(NNpy)(PMe(2)Ph)(2)Cl](+)[Cl](-) (2) contains a chelated, neutral organodiazene ligand and a linear, diazenido(1-) ligand. The X-ray structural analysis of 2, C(26)H(30)Cl(2)N(6)P(2)Re, indicates a delocalized pi-system formed by the chelate ring. The (1)H NMR spectrum of 2 is not paramagnetically shifted. Complex 2 crystallizes in the orthorhombic space group Pna2(1) with a = 17.383(4) Å, b = 13.967(3) Å, c = 12.002(2) Å, V = 2913.9(10) Å(3), Z = 4, and R = 0.0384 based on 3083 unique reflections.