title: Fluoridonitrosyl complexes of technetium(I) and technetium(II). Synthesis, characterization, reactions, and DFT calculations.
abstract: A mixture of [Tc(NO)F5](2-) and [Tc(NO)(NH3)4F](+) is formed during the reaction of pertechnetate with acetohydroxamic acid (Haha) in aqueous HF. The blue pentafluoridonitrosyltechnetate(II) has been isolated in crystalline form as potassium and rubidium salts, while the orange-red ammine complex crystallizes as bifluoride or PF6(-) salts. Reactions of [Tc(NO)F5](2-) salts with HCl give the corresponding [Tc(NO)Cl4/5](-/2-) complexes, while reflux in neat pyridine (py) results in the formation of the technetium(I) cation [Tc(NO)(py)4F](+), which can be crystallized as hexafluoridophosphate. The same compound can be synthesized directly from pertechnetate, Haha, HF, and py or by a ligand-exchange procedure starting from [Tc(NO)(NH3)4F](HF2). The technetium(I) cation [Tc(NO)(NH3)4F](+) can be oxidized electrochemically or by the reaction with Ce(SO4)2 to give the corresponding Tc(II) compound [Tc(NO)(NH3)4F](2+). The fluorido ligand in [Tc(NO)(NH3)4F](+) can be replaced by CF3COO(-), leaving the "[Tc(NO)(NH3)4](2+) core" untouched. The experimental results are confirmed by density functional theory calculations on [Tc(NO)F5](2-), [Tc(NO)(py)4F](+), [Tc(NO)(NH3)4F](+), and [Tc(NO)(NH3)4F](2+).
authors.affiliation: Institute of Chemistry and Biochemistry, Freie Universität Berlin , Fabeckstr. 34/36, D-14195 Berlin, Germany.
authors.forename: Samundeeswari Mariappan
authors.initials: SM
authors.lastname: Balasekaran
authors.forename: Johann
authors.initials: J
authors.lastname: Spandl
authors.forename: Adelheid
authors.initials: A
authors.lastname: Hagenbach
authors.forename: Klaus
authors.initials: K
authors.lastname: Köhler
authors.forename: Markus
authors.initials: M
authors.lastname: Drees
authors.forename: Ulrich
authors.initials: U
authors.lastname: Abram
mesh_terms: D056831:Coordination Complexes / Q000138:chemical synthesis* / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D015394:Molecular Structure; D009603:Nitroso Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013667:Technetium / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D009603:Nitroso Compounds; D013667:Technetium