82293-79-6Relevant articles and documents
Reactivity of the Metallocarboxylates Cp(NO)(PPh3)ReCO2-M+ toward Excess Carbon Dioxide: Degradation to a Bimetallic μ-[η1-C(Re):η1-O,O′(Re′)] Carbon Dioxide Complex Cp(NO)(PPh3)ReCO2Re(NO)(CO)(PPh3)(η 1-C5H5)
Tetrick, Stephen M.,Cutler, Alan R.
, p. 1741 - 1746 (1999)
The rhenium η1C carboxylate Cp(PPh3)(NO)ReCO2-(1Li+ or 1K+) undergoes an unusual reductive disproportionation sequence in the presence of excess CO2 that generates a new Re2(μ2-η3-CO2) complex Cp(PPh3)(NO)ReCO2Re(CO)(NO)(PPh3)(η 1-Cp) (2) plus CO32-. The overall stoichiometry entails 3 equiv of CO2 plus 2 equiv of Cp(PPh3)(NO)ReLi transforming to ligated CO2 and CO (i.e., 2) plus CO32-. Three procedures were used to generate 2: treating (a) Cp(PPh3)(NO)ReLi with excess CO2, (b) 1K+ with excess CO2, and (c) 1K+ with Cp(PPh3)-(NO)Re(CO)BF4. The results of this study are consistent with the intermediacy of an undetected metalloanhydride Cp(PPh3XNO)ReC(O)OC(O)Re(NO)(PPh3)Cp (8), which upon a subsequent η5→η1 Cp ring shift on one rhenium center affords 2. This product undergoes different solvolysis reactions in the presence of methanol and triethylsilanol. The former gives 2 equiv of the methyl ester Cp(NO)(PPh3)ReCO2CH3 (6), whereas the latter replaces the η1-Cp group with a silanolate to give the previously characterized Cp(PPh3)(NO)ReCO2-Re(CO)(NO)(PPh3)(OSiEt 3) (5a).
SynThesis, Optical Resolution, and Absoiyte - Pseudotetrahedrai organorheniym complexes (i7-C5H5)Re(NO)(PPh,)(X)
Merrifield, James H.,Strouse, Charles T,Giadysz
, p. 1204 - 1211 (2008/10/08)
Reaction of [(C6H5)Re(NO)(PPh3)(CO)]+BF,r (1) with CH,ONa/CH3OH affords the ester (??C5H6)Re(NO)(PPh3)(COOCH3) (2). Reaction of 2 with (-)-(S)-a-(l-naphthyi)ethyIamine or (+)-(R)-a(l-naphthyl)ethykmine gives amide (^C6H5)Re(NO)(PPh3XCO:NHCH(CH3)C10H7) (8). The diastereomers of 8 are separated by benzene/hexane reerystallization; (-)-(BS)-8 and (+)-(SA)-8 are least soluble. These are treated with CF3C02H and NaBF4 to give (-)-(A)-l and (+)-(S)-l, respectively. Resolved 1 is then used to prepare optically active 2, (i?-C5HB)Re(NO)(PPh3)(CH8) (3), [()7-C5H5)Re(NO}(PPh3)(==H2)]+PF6-(4), (i7-C5H6)Re(NO)(PPhg)(CH2C6H 5) (9), (7j-C5HB)Re(NO){PPh3){CH2CH3) (10), and (7?-C5H5)Re(NO)(PPh3)(CHO) (11) via known procedures. An X-ray crystal structure of (-)-(A)-9 (space group P212121, a = 12.874 (5) A, b = 11.889 (3) A, c = 16.077 (7) K,Z~4,R = 0.034) establishes the absolute configurations of resolved 1-4 and 8-11. Also described are the following: ORD and CD spectra; several unsuccessful resolution attempts; the synthesis of [(jl-C5H5)Re(NO)(PPh3)(CH 2P+Ph2(0-i-menthyl))]+PF6+ (?) (used as an optical purity assay); comparisons with isostructural chiral organometallic complexes.
