Synthesis and Reactivity of Bis(tetramethylcyclopentadienyl) Yttrium Metallocenes Including the Reduction of Me3SiN3 to [(Me3Si)2N]− with [(C5Me4H)2Y(THF)]2(μ-η2:η2-N2)

The metallocene precursors needed to provide the tetramethylcyclopentadienyl yttrium complexes (C5Me4H)3Y, [(C5Me4H)2Y(THF)]2(μ-η2:η2-N2), and [(C5Me4H)2Y(μ-H)]2 for reactivity studies have been synthesized and fully characterized, and their reaction chemistry has led to an unexpected conversion of an azide to an amide. (C5Me4H)2Y(μ-Cl)2K(THF) x , 1, synthesized from YCl3 and KC5Me4H reacts with allylmagnesium chloride to make (C5Me4H)2Y(η3-C3H5), 2, which is converted to [(C5Me4H)2Y][(μ-Ph)2BPh2], 3, with [Et3NH][BPh4]. Complex 3 reacts with KC5Me4H to form (C5Me4H)3Y, 4. The reduced dinitrogen complex, [(C5Me4H)2Y(THF)]2(μ-η2:η2-N2), 5, can be synthesized from either [(C5Me4H)2Y]2[(μ-Ph)2BPh2], 3, or (C5Me4H)3Y, 4, with potassium graphite under a dinitrogen atmosphere. The 15N labeled analogue, [(C5Me4H)2Y(THF)]2(μ-η2:η2-15N2), 5- 15 N, has also been prepared, and the 15N NMR data have been compared to previously characterized reduced dinitrogen complexes. Complex 2 reacts with H2 to form the corresponding hydride, [(C5Me4H)2Y(μ-H)]2, 6. Complex 5 displays similar reactivity to that of the analogous [(C5Me4H)2Ln(THF)]2(μ-η2:η2-N2) complexes (Ln = La, Lu), with substrates such as phenazine, anthracene, and CO2. In addition, 5 reduces Me3SiN3 to form (C5Me4H)2Y[N(SiMe3)2], 7.