82293-79-6Relevant academic research and scientific papers
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 and chemistry of chiral rhenium acyls (η-C5H5)Re(NO)(PPh3)(COR)
Buhro, William E.,Wong, Andrew,Merrifield, James H.,Lin, Gong-Yu,Constable, Anthony C.,Gladysz
, p. 1852 - 1859 (2008/10/08)
Rhenium acyls (η-C5H5)Re(NO)(PPh3)(COR) (R = CH3 (2), CH2CH3 (3), CH2-n-C8H17 (4), C6H5 (5), CH2C6H5 (6), CH2CH2C6H5 (7), CH=CH2 (8), CH2CH=CH2 (9)) are prepared in high yield by RMgX attack upon (η-C5H5)Re(NO)(PPh3)(COOCH3) (1). Acyl (η-C5H5)Re(NO)(PPh3)(COC≡CCH 3) (10) is prepared by LiC≡CCH3 attack upon [(η-C5H5)Re(NO)(PPh3)(CO)] +BF4-. Acyls 2, 5, and 7 are also prepared in optically active form from optically active 1. These compounds are characterized by IR, 1H NMR, 13C NMR, and (when optically active) ORD and CD. They are shown to undergo high-yield (1) BH3 reduction ((-)-(R)-2, 4, (+)-(R)-5, 7) to the corresponding alkyls (η-C5H5)Re(NO)(PPh3)(CH2R), (2) methylation with CH3SO3F/NH4+ PF6- (2, 5) to methoxycarbenes [(η-C5H5)Re(NO)(PPh3)(=C(OCH 3)R)]+ PF6-, and (3) protonation with CF3SO3H (2, 3) to hydroxycarbenes [(η-C5H5)Re(NO)(PPh3)(=C(OH)R)] +CF3SO3-. Structures for the preferred conformers of 2-10 and their methylation and protonation products are suggested.
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.
