Divergent kinetic and thermodynamic acidity in organotransition-metal hydride complexes: synthesis, structure, and reactivity of the rhenium anion of Li/sup +/((/eta//sup 5/-C/sub 5/H/sub 5/)Re(NO)(PPh/sub 3/))/sup /minus//
Reaction of hydride complex (/eta//sup 5/-C/sub 5/H/sub 5/)Re(NO)(PPh/sub 3/)(H) (1) and n-BuLi/TMEDA (THF, /minus/78/degree/C) gives (/eta//sup 5/-C/sub 5/H/sub 4/Li)Re(NO)(PPh/sub 3/)(H)(Li/sup +/-8), as shown by /sup 31/P NMR monitoring, deuterium labeling, and methylation (CH/sub 3/OSO/sub 2/CF/sub 3/, /minus/78/degree/C) to (/eta//sup 5/-C/sub 5/H/sub 4/CH/sub 3/)Re(NO)(PPh/sub 3/)(H) (9, 52%). Complex Li/sup +/-8 rearranges to the rhenium anion of Li/sup +/((/eta//sup 5/-C/sub 5/H/sub 5/)Re(NO)(PPh/sub 3/))/sup /minus// (Li/sup +/-3; /minus/32/degree/C, 0.5 h) with /Delta/H/double dagger/ = 11.3 /plus minus/ 0.5 kcal/mol, /Delta/S/double dagger/ = /minus/26.2 /plus minus/ 1.4 eu, and k/sub H//k/sub D/ (/minus/22.4/degree/C) = 1.16 /plus minus/ 0.08. Crossover experiments show hydrogen migration to be intramolecular, and K/sup +/-8 rearranges ca. 10/sup 4/ faster than Li/sup +/-8 at /minus/91.6/degree/C. Equilibration experiments show the /eta//sup 5/-C/sub 5/H/sub 5/ and ReH proton pK/sub a/'s (THF) in 1 to be ca. 36 and 26-30, respectively. Thus, the less acidic proton is abstracted kinetically, and a rationale is proposed. Reactions of Li/sup +/-3 with alkylating agents (CH/sub 3/I, n-C/sub 4/H/sub 9/I, ClCH/sub 2/CH/emdash/CH/sub 2/, ClCH/sub 2/COPh), benzoic anhydride, and D/sub 2/O give the corresponding alkyl, acyl, and deuteride complexes (56-90%). IR data show Li/sup +/-3 to be a mixture of three ion pairs in THF. Pentamethyl analogue (/eta//sup 5/-C/sub 5/Me/sub 5/)Re(NO)(PPh/sub 3/)(H) (13) is prepared from methyl complex (/eta//sup 5/C/sub 5/Me/sub 5/)Re(NO)(PPh/sub 3/)(CH/sub 3/) (11; HCOOH, then 110/degree/C; 43%). Reaction of 13 and n-BuLi/K/sup +/-t-BuO/sup /minus//gives principally K/sup +/((/eta//sup 5/-C/sub 5/Me/sub 5/)Re(NO)(PPh/sub 3/))/sup /minus//, as assayed by /sup 31/P NMR and methylation (CH/sub 3/I) to 11.
- Research Organization:
- Univ. of Utah, Salt Lake City (USA)
- OSTI ID:
- 5914159
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:18
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HYDRIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
ORGANOMETALLIC COMPOUNDS
RHENIUM COMPLEXES
ANIONS
CARBON 13
CATALYSIS
CHEMICAL REACTION KINETICS
EXPERIMENTAL DATA
HYDROGEN 1
INFRARED SPECTRA
LIGANDS
MASS SPECTROSCOPY
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
PH VALUE
THERMODYNAMIC PROPERTIES
THERMODYNAMICS
CARBON ISOTOPES
CHARGED PARTICLES
COMPLEXES
DATA
EVEN-ODD NUCLEI
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INFORMATION
IONS
ISOTOPES
KINETICS
LIGHT NUCLEI
MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PHYSICAL PROPERTIES
REACTION KINETICS
RESONANCE
SPECTRA
SPECTROSCOPY
STABLE ISOTOPES
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties