Fluxionality and isomerism of the bis(dihydrogen) complex RuH{sub 2}(H{sub 2}){sub 2}(PCy{sub 3}){sub 2}: INS, NMR, and theoretical studies
- CNRS, Toulouse (France). Lab. de Chimie de Coordination; and others
To study the fluxionality of the bis(dihydrogen) complex RuH{sub 2}(H{sub 2}){sub 2}(PCy{sub 3}){sub 2} (1), NMR spectra were recorded in Freons. 1 was found to remain fluxional at all temperatures, but the presence of CDCl{sub 3} necessary for its solubilization induces its transformation into, first, RuHCl(H{sub 2}){sub 2}(PCy{sub 3}){sub 2} (3) and the new ruthenium(IV) dihydride RuH{sub 2}Cl{sub 2}(PCy{sub 3}){sub 2} (4). 4 is produced selectively in pure CDCl{sub 3} but reacts further to give a mixture of chloro complexes. 4 was isolated from the reaction of 1 with aqueous HCl in Et{sub 2}O and shows a fluxional process attributed to the interconversion between two symmetrical isomers. The activation parameters of this process were obtained by {sup 1}H NMR line shape analysis, as well as those corresponding to the exchange between 3 and free dihydrogen. The geometries and relative energies of several isomers of complexes 1, 3, and 4 were studied using density functional theory (DFT) and MP2 methods, together with a few coupled-cluster (CCSD-(T)) calculations. In contrast to what might have been expected, the two hydrides and the two H{sub 2} units of 1 lie in the same plane. Rotation of the two dihydrogen ligands has been analyzed using DFT calculations. Two low-energy isomers of 4 have been characterized computationally, both of which have C{sub 2v} symmetry, consistent with the solution NMR spectra.
- OSTI ID:
- 653416
- Journal Information:
- Inorganic Chemistry, Journal Name: Inorganic Chemistry Journal Issue: 14 Vol. 37; ISSN 0020-1669; ISSN INOCAJ
- Country of Publication:
- United States
- Language:
- English
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