137167-68-1Relevant academic research and scientific papers
[ReH2(CO)2(PMe2Ph)3] +, a dihydride complex with classical and nonclassical tautomeric forms in equilibrium
Luo, Xiao-Liang,Michos, Demetrius,Crabtree, Robert H.
, p. 237 - 241 (2008/10/08)
Reactions of [ReH3(CO)(PMe2Ph)3] (1) with PMe2Ph or CO in refluxing THF give the monohydride complexes trans-ReH(CO)(PMe2Ph)4 (2) and cis,mer-[ReH(CO)2(PMe2Ph)3] (3), respectively. Protonation of 2 with HBF4·OMe2 in CH2Cl2 at 298 K gives the classical dihydride complex [ReH2(CO)2(PMe2Ph)3]+ (4), while protonation of 3 in CD2Cl2 at 193 K results in an equilibrium mixture of the classical dihydride complex [ReH2(CO)2(PMe2Ph)3]+ (5a) and its nonclassical dihydrogen tautomer [Re(η2-H2)(CO)2(PMe2Ph) 3]+ (5b). The η2-HD isotopomer of 5b, formed by protonation of the corresponding monodeuteride complex, shows a 1JHD value of 31 Hz in the 1H NMR spectrum. Variable-temperature 1H NMR equilibrium studies for the conversion of 5a to 5b produce the thermodynamic parameters ΔH = 1.7 ± 0.4 kcal mol-1 and ΔS = 8 ± 3 cal mol-1 K-1. The lower limit of ΔG≠ for the conversion of 5b to 5a at 223 K is estimated to be 11.5 ± 0.3 kcal mol-1.
