NMR Study of the Solution Structures of TcO2F3 and ReO2F3

Both TcO(2)F(3) and ReO(2)F(3) are infinite chain, fluorine-bridged polymers in the solid state. Their solution structures have been studied by (19)F and (99)Tc NMR spectroscopy in SO(2)ClF solution and shown to exhibit cyclic (MO(2)F(3))(3) (M = Tc, Re) and (ReO(2)F(3))(4) structures that have been confirmed by simulation of the (19)F NMR spectra. The trimers dominate in both the technetium and rhenium systems, with both the tetramer and trimer existing in equilibrium in the rhenium system. A low concentration of a higher, possibly pentameric, cyclic rhenium polymorph is also present in equilibrium with the trimer and tetramer.