THE REACTION CHEMISTRY OF A TECHNETIUM(I) NITROSYL COMPLEX WITH POTENTIALLY CHELATING ORGANOHYDRAZINES - THE X-RAY CRYSTAL-STRUCTURE OF [TCCL2(NO)(HN=NC5H4N)(PPH3)]

The reaction of the nitrosyl complex [TcCl2(NO) (MeCN)) (PPh3)(2)] wit h 2-hydrazinopyridine dihydrochloride in refluxing MeOH gives the purp le complex [TcCl2(NO) (HN = NC5H4N) (PPh3)(2)] (1) in which the neutra l bidentate organodiazene ligand has replaced the acetonitrile and a p hosphine ligand. The IR spectrum of 1 shows a very strong absorption a t 1732 cm(-1) attributed to v(N = O). The FAB (+) mass spectrum of 1 d isplays the protonated parent ion at 570 m/z and the fragment generate d by the loss of a chloride ligand from the parent ion at 533 m/z. The H-1 NMR spectrum of this diamagnetic complex displays the signal from the a-nitrogen-proton of the pyridyldiazene at 17.95 ppm as well as t he aryl-protons. The X-ray crystal structure of this complex shows a d istorted octahedral coordination geometry. The Tc-N bond length of 1.7 52(4) Angstrom is consistent with the multiple bonding expected for th e linearly bonded nitrosyl ligand. The Tc-N-O bond angle is 175.1(4)de grees. The N-Tc-N bond angle of the chelated pyridyldiazene ligand is 73.1(2)degrees, which reflects the small bite angle imposed by the fiv e-membered chelate ring of this ligand. The reaction of the nitrosyl c omplex [TcCl2(NO) (MeCN)) (PPh3)(2)] with 2-hydrazino-4-trifluoromethy lpyrimidine in refluxing dichloromethane gives the neutral Tc(I) compl ex [TcCl(NO) (N = NC4H2N2-R) (PPh3)(2)] (2) in which the anionic biden tate organodiazenido ligand has replaced the acetonitrile and a chlori de ligand. The IR spectrum of 2 shows a very strong absorption at 1717 cm(-1) attributed to v(N = O). The FAB (+) mass spectrum of 2 display s the parent ion at 866 m/z as well as the fragment generated by the l oss of the diazenido ligand at 688 m/z. The peak associated with the l oss of a phosphine ligand from the parent ion at 604 m/z is also evide nt. (C) 1998 Elsevier Science S.A. All rights reserved.