Protonation of metal hydrides by strong acids. Formation of an equilibrium mixture of dihydride and dihydrogen complexes from protonation of Cp{sup *}Os(CO){sub 2}H. Structural characterization of [CpW(CO){sub 2}(PMe{sub 3})(H){sub 2}]{sup +}OTf{sup -}
- Brookhaven National Lab., Upton, NY (United States)
Cp{sup *}Os(CO){sub 2}H is protonated by triflic acid (HOTf) in CD{sub 2} Cl{sub 2} solution to give an equilibrium mixture (87:13) of the dihydride [Cp{sup *}Os(CO){sub 2}(H){sub 2}]{sup +}OTf{sup -} and the dihydrogen complex [Cp{sup *}Os(CO){sub 2}({eta}{sup 2}-H{sub 2})]{sup +}OTf{sup -}. The acidity of these protonated species is roughly comparable to HOTf, since only partial protonation was observed. In the absence of acid, the T{sub 1} of the hydride ligand of Cp{sup *}Os(CO){sub 2}H is 5.9 s at -80{degree}C. When all of the Cp{sup *}Os(CO){sub 2}H is protonated by excess HOTf,the T{sub l} (-80{degree}C) of the terminal hydride ligands of [Cp{sup *}Os(CO){sub 2}(H){sub 2}]{sup +}OTf{sup -} is 2.8 s, while the T{sub l} of the dihydrogen ligand of [Cp{sup *}Os(CO){sub 2}({eta}{sup 2}-H{sub 2})]{sup +} OTf{sup -} is 19 ms, (-80{degree}C). The observed T{sub l} values of the Os-H resonance of Cp{sup *}Os(CO){sub 2}H decreased significantly under conditions of partial protonation, indicating intermolecular proton transfer among [Cp{sup *}Os(CO){sub 2}({eta}{sup 2}H{sub 2})]{sup +}OTf{sup -}, [Cp{sup *}Os(CO){sub 2}(H){sub 2}]{sup +}OTf{sup -}, Cp{sup *}Os(CO){sub 2}H, and HOTf. IR spectra indicate that the two CO ligands of [Cp{sup *}Os(CO){sub 2}(H){sub 2}]{sup +} (and hence the hydrides as well) are trans to each other in the four-legged piano stool geometry. 62 refs., 6 figs., 8 tabs.
- Research Organization:
- Brookhaven National Laboratory (BNL), Upton, NY
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 249563
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 10 Vol. 15; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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