Insertion of isocyanides into the Zr-C bond of ruthenium/zirconium dimetalloalkenes. Spectroscopic and structural comparisons of the {eta}{sup 2}-iminoacyl complexes Cp(PMe{sub 3}){sub 2}RuCH=CRC(N{sup t}Bu)ZrClCp{sub 2} (R = H vs R = Me) and kinetics of isomerization of a thermodynamically unstable {eta}{sup 2}-iminoacyl complex
- Brookhaven National Lab., Upton, NY (United States)
The reaction of Cp(PMe{sub 3}){sub 2}RuCH{double_bond}CHZrClCp{sub 2} with {sup t}BuNC produces an {eta}{sup 2}-iminoacyl complex, Cp-(PMe{sub 3}){sub 2}RuCH{double_bond}CHC(N{sup t}Bu)ZrClCp{sub 2}. The initially formed isomer of this compound is the {open_quotes}N-outside{close_quotes} isomer (2Hk), where the N-donor portion of the {eta}{sup 2}-iminoacyl ligand is on the outside position of the three ligation sites of the Cp{sub 2}Zr moiety. This kinetic isomer cleanly rearranges to the thermodynamic {open_quotes}N-inside{close_quotes} isomer (2Ht). Activation parameters determined for this rearrangement are {Delta}H{sup {double_dagger}} = 19.9 {+-} 0.6 kcal mol{sup -1}, {Delta}S{sup {double_dagger}} = -3.4 {+-} 2.2 cal K{sup -1} mol{sup -1}, and {Delta}G{sup {double_dagger}}(298 K) = 20.9 kcal mol{sup -1}. Spectroscopic and crystallographic data for 2Ht indicate a significant contribution from a zwitterionic resonance form that is facilitated by the disparate electronic properties of the electron-rich ruthenium and the electron-deficient zirconium moieties. The reaction of {sup t}BuNC with the analogous methylated dimetalloalkene Cp(PMe{sub 3}){sub 2}RuCH{double_bond}C-(CH{sub 3})ZrClCp{sub 2} gives the {eta}{sup 2}-iminoacyl complex Cp(PMe{sub 3}){sub 2}RuCH{double_bond}C(CH{sub 3})C(N{sup t}Bu)ZrClCp{sub 2} (2Me). 13 refs., 6 figs., 9 tabs.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 555334
- Journal Information:
- Organometallics, Vol. 11, Issue 2; Other Information: PBD: Feb 1992
- Country of Publication:
- United States
- Language:
- English
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