The synthesis and characterization of [MCl 3(NNC 5H 4NH) (HNNC 5H 4N) from [MO 4] − (where MRe, Tc) organodiazenido, organodiazene-chelate complexes. The X-ray structure of [ReCl 3 (NNC 5H 4NH) (HNNC 5H 4N)

Abstract

The reaction of Na[ReO 4] with 2-hydrazinopyridine dihydrochloride in methanol gives [ReCl 3(NNC 5H 4NH) (HNNC 5H 4N)] 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 [ReCl 2(NNHC 5H 4N) (HNNC 5H 4N)] + 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 ReCl 3N 6C 10H 10: triclinic space group P1, unit cell dimensions: a = 7.527(2), b = 7.599(2), c = 13.118(3) A ̊ , α = 106.55(3), β = 90.28(3), γ = 93.83(3)°, V = 717.4(4) A ̊ 3 , 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 [TcCl 3(NNC 5H 4NH)-(HNNC 5H 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 HCl of 383 m/z. The reaction of the rhenium complex with stoichiometric amounts of triphenylphosphine and a proton scavenger gives [ReCl 2(PPh 3)(NNC 5H 4N) (HNNC 5H 4N)], an organodiazenido-organodiazene complex in which the phosphine has replaced one of the chloride ligands accompanied by the loss of the pyridium proton from the organodiazenido ligand.