Reduction of the pertechnetate anion with bidentate phosphine ligands.
The reduction of ammonium pertechnetate with bis(diphenylphosphino)methane (dppm), and with diphenyl-2-pyridyl phosphine (Ph(2)Ppy), has been investigated. The neutral Tc(II) complex, trans-TcCl(2)(dppm)(2) (1), has been isolated from the reaction of (NH(4))[TcO(4)] with excess dppm in refluxing EtOH/HCl. Chemical oxidation with ferricinium hexafluorophosphate results in formation of the cationic Tc(III) analogue, trans-[TcCl(2)(dppm)(2)](PF(6)) (2). The dppm ligands adopt the chelating bonding mode in both complexes, resulting in strained four member metallocycles. With excess PhPpy, the reduction of (NH(4))[TcO(4)] in refluxing EtOH/HCl yields a complex with one chelating Ph(2)Ppy ligand and one unidentate Ph(2)Ppy ligand, mer-TcCl(3)(Ph(2)Ppy-P,N)(Ph(2)Ppy-P) (3). The cationic Tc(III) complexes, trans-[TcCl(2)(Ph(2)P(O)py-N,O)(2)](PF(6)) (4) and trans-[TcCl(2)(dppmO-P,O)(2)](PF(6)) (5) (Ph(2)P(O)py = diphenyl-2-pyridyl phosphine monoxide and dppmO = bis(diphenylphosphino)methane monoxide), have been isolated as byproducts from the reactions of (NH(4))[TcO(4)] with the corresponding phosphine. The products have been characterized in the solid state and in solution via a combination of single-crystal X-ray crystallography and spectroscopic techniques. The solution state spectroscopic results are consistent with the retention of the bonding modes revealed in the crystal structures.
Freiberg
Evan
E
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Davis
William M
WM
Nicholson
Terrence
T
Davison
Alan
A
Jones
Alun G
AG
D002614:Chelating Agents; D018360:Crystallography, X-Ray; D007202:Indicators and Reagents; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D010720:Phosphines / Q000737:chemistry*; D019275:Radiopharmaceuticals / Q000138:chemical synthesis / Q000737:chemistry*; D013670:Sodium Pertechnetate Tc 99m / Q000138:chemical synthesis / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
D002614:Chelating Agents; D007202:Indicators and Reagents; D008024:Ligands; D010720:Phosphines; D019275:Radiopharmaceuticals; D013670:Sodium Pertechnetate Tc 99m