433927-23-2Relevant academic research and scientific papers
Synthesis and investigation of [Cp*(PMe3)Rh(H)(H2)]+ and its partially deuterated and tritiated isotopomers: Evidence for a hydride/dihydrogen structure
Taw, Felicia L.,Mellows, Heather,White, Peter S.,Hollander, Frederick J.,Bergman, Robert G.,Brookhart, Maurice,Heinekey, D. Michael
, p. 5100 - 5108 (2007/10/03)
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 T1 (T1(min) = 23 ms at 150 K, 500 MHz), JH-D (ca. 10 Hz), and JH-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(u-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.
