End-to-End Rotation of Rhenium-Bound Dinitrogen

Autor:	Derek Sutton, Antonio Cusanelli
Rok vydání:	1996
Předmět:	Stereochemistry Organic Chemistry chemistry.chemical_element Rhenium Medicinal chemistry Inorganic Chemistry NMR spectra database chemistry.chemical_compound Reaction rate constant chemistry Reagent Acetone Physical and Theoretical Chemistry Isomerization
Zdroj:	Organometallics. 15:1457-1464
ISSN:	1520-6041 0276-7333
DOI:	10.1021/om950792j
Popis:	The singly 15N-labeled dinitrogen complexes Cp‘Re(CO)(L)(15N14N) (Cp‘ = η5-C5H5, L = CO (1-15Nα) and Cp‘ = η5-C5Me5, L = CO (2-15Nα), PMe3 (3-15Nα), or P(OMe)3 (4-15Nα)) were synthesized from the corresponding aryldiazenido complex [Cp‘Re(CO)(L)(15N14NC6H4OMe)][BF4] by treatment with Ph3C, Cp2Co, Na/Hg, or NaBH4. When these dinitrogen complexes are freshly synthesized, the 15N label is exclusively retained in the metal-bound (Nα) position irrespective of the reagent used. At 291 K 1-15Nα isomerizes in acetone to give a 1:1 mixture of 1-15Nα and 1-15Nβ, as indicated by the intensities of the 15Nα and 15Nβ resonances in the 15N NMR spectra, with rate constant kobs = (48 ± 6) × 10-6 s-1 and ΔG⧧ = 95.3 ± 0.5 kJ mol-1. For 2-15Nα isomerization occurs similarly, and the temperature dependence over the range 274−291 K yielded ΔG⧧291 = 92.6 ± 0.4 kJ mol-1, ΔH⧧ = 105.3 ± 6.0 kJ mol-1, ΔS⧧ = 43.5 ± 21.2 J mol-1 K-1, Ea = 106.8 ± 5.4 kJ mol-1, and A = (2.1 ± 1.3) × 10-15 s-1. As a consequence of the linkage isomeriz...
Databáze:	OpenAIRE
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