[Tc II (NO)(trifluoroacetate) 4 F] 2- - synthesis and reactions.

Fluoridotetrakis(trifluoroacetato)nitrosyltechnetate(ii) was prepared by the dissolution of Cs2 [Tc(NO)F5 ] in trifluoroacetic acid and addition of (NBu4 )F·3H2 O. The compound crystallizes as a mixed Cs+ /NBu4 + salt in the form of green crystals. Unlike the [Tc(NO)F5 ]2- salts, the product is soluble in organic solvents and can be used as a precursor for ongoing ligand exchange procedures with organic ligands. The corresponding reactions with triphenylphosphine (PPh3 ), 1,2-bis(diphenylphosphino)ethane (DPPE) or pyridyldiphenylphosphine (pyPPh2 ) give technetium(i) complexes of the compositions Cs[Tc(NO)(PPh3 )2 (CF3 COO)2 F], [Tc(NO)(DPPE)2 (OOCCF3 )](PF6 ) and [Tc(NO)(κN,P-pyPPh2 )(κP-pyPPh2 )(CF3 COO)2 ]. The products were studied spectroscopically and by X-ray diffraction. The99 Tc NMR resonances of the novel Tc(i) nitrosyls appear between -627 and +952 ppm, which is at a remarkably high field and in the range where normally the signals of Tc(iii) compounds are observed.