Details

Autor(en) / Beteiligte

• Taw, Felicia L
• Mellows, Heather
• White, Peter S
• Hollander, Frederick J
• Bergman, Robert G
• Brookhart, Maurice
• Heinekey, D. Michael

Titel

Synthesis and Investigation of [Cp(PMe3)Rh(H)(H2)]+ and Its Partially Deuterated and Tritiated Isotopomers:  Evidence for a Hydride/Dihydrogen Structure

Ist Teil von

• Journal of the American Chemical Society, 2002-05, Vol.124 (18), p.5100-5108

Ort / Verlag

Washington, DC: American Chemical Society

Erscheinungsjahr

2002

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• Hydrogenolysis of [Cp*(PMe3)Rh(Me)(CH2Cl2)]+BAr‘4 - (4, Ar‘ = 3,5-C6H3(CF3)2) in dichloromethane afforded the nonclassical polyhydride complex [Cp*(PMe3)Rh(H)(H2)]+BAr‘4 - (1), which exhibits a single hydride resonance at all accessible temperatures in the 1H NMR spectrum. Exposure of solutions of 1 to D2 or T2 gas resulted in partial isotopic substitution in the hydride sites. Formulation of 1 as a hydride/dihydrogen complex was based upon T 1 (T 1(min) = 23 ms at 150 K, 500 MHz), J H - D (ca. 10 Hz), and J H - T (ca. 70 Hz) measurements. The barrier (ΔG ⧧) to exchange of hydride with dihydrogen sites was determined to be less than ca. 5 kcal/mol. Protonation of Cp*(PMe3)Rh(H)2 (2) using H(OEt2)2BAr‘4 resulted in binuclear species [(Cp*(PMe3)Rh(H))2(μ-H)]+BAr‘4 - (3), which is formed in a reaction involving 1 as an intermediate. Complex 3 contains two terminal hydrides and one bridging hydride ligand which exchange with a barrier of 9.1 kcal/mol as observed by 1H NMR spectroscopy. Additionally, the structures of 3 and 4, determined by X-ray diffraction, are reported.