The reaction chemistry of a technetium(I) nitrosyl complex with potentially chelating organohydrazines: the X-ray crystal structure of [TcCl 2(NO) (HNNC 5H 4N) (PPh 3)

Abstract

The reaction of the nitrosyl complex [TcCl 2(NO)(MeCN))(PPh 3) 2] with 2-hydrazinopyridine dihydrochloride in refluxing MeOH gives the purple complex (TcCl 2(NO) (HN)NC 3H 4N) (PPh 2] ( 1) in which the neutral bidentate organodiazene ligand has replaced the acetonitrile and a phosphine ligand. The IR spectrum of 1 shows a very strong absorption at 1732 cm −1 attributed to v(NO). The FAB(+) mass spectrum of 1 displays the protonated parent ion at 570 m/z and the fragment generated by the loss of a chloride ligand from the parent ion at 533 m/ z. The 1H NMR spectrum of this diamagnetic complex displays the signal from the α-nitrogen-proton of the pyridyldiazene at 17.95 ppm as well as the aryl-protons. The X-ray crystal structure of this complex shows a distorted octahedral coordination geometry. The TcN bond length of 1.752(4) Å is consistent with the multiple bonding expected for the linearly bonded nitrosyl ligand. The TcNO bond angle is 175.1(4)°. The NTcN bond angle of the chelated pyridyldiazene ligand is 73.1(2)°, which reflects the small bite angle imposed by the five-membered chelate ring of this ligand. The reaction of the nitrosyl complex [TcCl 2(NO)(MeCN))(PPh 3) 2] with 2-hydrazino-4-trifluoromethylpyrimidine in refluxing dichloromethane gives the neutral Tc(I) complex [TcCl(NO) (NNC 4H 2N 2R)(PPh 3) 2] in which the anionic bidentate organodiazenido ligand has replaced the acetonitrile and a chloride 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 displays the parent ion at 886 m/ z as well as the fragment generated by the loss of the diazenido ligand at 688 m/ z. The peak associated with the loss of a phosphine ligand from the parent ion at 604 m/ z is also evident.