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), Journal Name: Organometallics; (United States) Vol. 13:6; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400102 -- Chemical & Spectral Procedures
400201* -- Chemical & Physicochemical Properties
ALKYLATION
CHEMICAL BONDS
CHEMICAL REACTIONS
COHERENT SCATTERING
COMPILED DATA
COMPLEXES
CRYSTALLOGRAPHY
DATA
DEUTERIUM COMPOUNDS
DIFFRACTION
HYDROGEN COMPOUNDS
INFORMATION
LABELLED COMPOUNDS
LIGANDS
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC SILICON COMPOUNDS
ORGANOMETALLIC COMPOUNDS
RESONANCE
RUTHENIUM COMPLEXES
SCATTERING
SYNTHESIS
TEMPERATURE DEPENDENCE
TRANSITION ELEMENT COMPLEXES
X-RAY DIFFRACTION