The synthesis and characterization of [MCL₃(N=NC₅H₄NH)(HN=NC₅H ₄N)] from [MO₄]^- (where M = Re, Tc) organodiazenido, organodiazene-chelate complexes. The X-ray structure of [ReCl₃(N=NC₅H₄NH) (HN=NC₅H₄N)]

The reaction of Na[ReO₄] with 2-hydrazinopyridine dihydrochloride in methanol gives [ReCl₃(N=NC₅H₄NH) (HN=NC₅H₄N)] in excellent yields. The neutral, six-coordinate complex contains a pyridinium-diazenido ligand and a bidentate organodiazene ligand chelated through the pyridine nitrogen atom. The IR spectrum of this complex displays a series of strong absorptions in the 1600-1150 cm^-1 region from the organohydrazide ligands. The FAB(+) mass spectrum displays the protonated parent ion of 507 m/z units and the fragment [ReCl₂(N=NHC₅H₄N) (HN=NC₅H₄N)]⁺ of 470 m/z. The X-ray structure displays a meridional arrangement of chloride ligands, and the pyridine nitrogen atom of the organodiazene chelate ligand trans to the singly-bent, organodiazenido ligand. The molecular coordination geometry is distorted octahedral. The Re-N bond length to the pyridine nitrogen atom of the organodiazene chelate is 2.164(7) Å, while the Re-N bond to the diazene α-nitrogen atom is 1.936(10) Å. The N-N bond length of this ligand is 1.309(11) Å, indicative of multiple bonding within the chelated ligand. The Re-N bond length of the pyridinium-diazenido ligand is 1.741(7) Å and the N-N bond length is 1.253(12) Å, again reflecting the multiple bonding throughout the organodiazenido unit. The bond angle for this linkage is 168.1(8)°. Crystal data for ReCl₃N₆C₁₀H₁₀: triclinic space group P1̄, unit cell dimensions: a = 7.527(2), b = 7.599(2), c = 13.118(3) Å, α = 106.55(3), β = 90.28(3), γ=93.83(3)°, V=717.4(4) ų, with D_calc = 2.346 Mg m^-3 to give Z = 2. Structure solution based on 2533 reflections converged at R = 3.61. The reaction of ammonium pertechnetate with 2-hydrazinopyridine-dihydrochloride in methanol gives [TcCl₃(N=NC₅H₄NH)-(HN=NC₅H ₄N)]. The ¹H NMR spectrum displays inequivalent organohydrazide ligands. The IR spectrum of the technetium complex displays an extended series of absorptions in the 1600-1150 cm^-1 region, analogous to the rhenium complex. The FAB(+) mass spectrum displays the protonated parent ion of 420 m/z as well as the fragment associated with the loss of HCI of 383 m/z. The reaction of the rhenium complex with stoichiometric amounts of triphenylphosphine and a proton scavenger gives [ReCl₂(PPh₃) (N=NC₅H₄N) (HN=NC₅H₄N)], an organodiazenido - organodiazene complex in which the phosphine has replaced one of the chloride ligands accompanied by the loss of the pyridinium proton from the organodiazenido ligand.