Addition of to a slurry of in tetrahydrofuran at –60 °C yielded an air-sensitive red sol...

Addition of to a slurry of in tetrahydrofuran at –60 °C yielded an air-sensitive red solution from which an anion Z was isolated. Z had strong infrared peaks at 1945 and 1811 cm^-1. (Note: has bands at 1921 and 1779 cm^-1. ) Other peaks are observed at 2495, 2132, and 2058 cm^-1; these are in the spectral region where B–H stretches commonly occur. The ¹H NMR spectrum at –95 °C showed broad singlets of relative intensity 3:1; these peaks became more complex at higher temperature. Propose a formula and structure for Z . (See P. J. Fischer, V. G. Young, Jr., J. E. Ellis, Angew. Chem. , Int. Ed. , 2000 , 39 , 189.)