Reversible silicon-carbon bond cleavage process. Dynamics and reactivity of Cp*[sub 2]Ru[sub 2]([mu]-CH[sub 2]) (SiMe[sub 3]) ([mu]-Cl)
- Univ. of Illinois, Urbana, IL (United States)
The methylene/silyl complex Cp*[sub 2]Ru[sub 2]([mu]-CH[sub 2]) (SiMe[sub 3])([mu]-Cl), where Cp* = C[sub 5]Me[sub 5], has been prepared by alkylation of [Cp*RuCl][sub 4] with 1 equiv of Mg(CH[sub 2]SiMe[sub 3])[sub 2]; the product is formed via the unusual cleavage of the [alpha]-C-Si bond of the alkyl group. The presence of a bridging methylene ligand and a terminal trimethylsilyl ligand has been demonstrated by [sup 1]H and [sup 13]C NMR spectroscopy and confirmed by an X-ray single crystal structure determination. Variable-temperature NMR spectroscopy shows that this molecule undergoes two dynamic processes: the lower temperature process ([Delta]H[sup [double dagger]] = 9.0 [+-] 0.2 kcal mol[sup [minus]1], [Delta]S[sup [double dagger]] = 0.5 [+-] 0.8 cal mol[sup [minus]1] K[sup [minus]1]) involves hopping of the silyl ligand between the two ruthenium centers, whereas the higher temperature process ([Delta]H[sup [double dagger]] = 12.0 [+-] 0.3 kcal mol[sup [minus]1], [Delta]S[sup [double dagger]] = -7 [+-] 1 cal mol[sup [minus]1] K[sup [minus]1]) involves the reversible reformation of the C-Si bond between the silyl and methylene ligands. Further evidence that the C-Si bond can be re-formed rests on the observation that treatment of Cp*[sub 2]Ru[sub 2]([mu]-CH[sub 2])-(SiMe[sub 3])([mu]-Cl) with PMe[sub 3] or CO instantly gives the mononuclear Ru[sup II] products Cp*Ru(CH[sub 2]-SiMe[sub 3])L[sub 2] (2) and Cp*RuClL[sub 2] (3), in essentially quantitative yield. 67 refs., 5 figs., 6 tabs.
- DOE Contract Number:
- FG02-91ER45439
- OSTI ID:
- 6980723
- Journal Information:
- Organometallics; (United States), Vol. 13:6; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANIC SILICON COMPOUNDS
NUCLEAR MAGNETIC RESONANCE
SYNTHESIS
X-RAY DIFFRACTION
RUTHENIUM COMPLEXES
ALKYLATION
CHEMICAL BONDS
COMPILED DATA
CRYSTALLOGRAPHY
DEUTERIUM COMPOUNDS
LABELLED COMPOUNDS
LIGANDS
ORGANOMETALLIC COMPOUNDS
TEMPERATURE DEPENDENCE
CHEMICAL REACTIONS
COHERENT SCATTERING
COMPLEXES
DATA
DIFFRACTION
HYDROGEN COMPOUNDS
INFORMATION
MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
RESONANCE
SCATTERING
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures