Chemistry of Highly Electrophilic Binuclear Cations. 5. Addition and C-C and C-P Coupling Processes in the Reactions of 1-Alkynes with the Dimolybdenum Radicals [Mo2(![]()
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- 作者：M. Angeles Alvarez ; Yvonne Anaya ; M. Esther Garcí ; a ; Miguel A. Ruiz ; and Jacqueline Vaissermann
- 刊名：Organometallics
- 出版年：2005
- 出版时间：May 9, 2005
- 年：2005
- 卷：24
- 期：10
- 页码：2452 - 2465
- 全文大小：277K
- 年卷期：v.24,no.10(May 9, 2005)
- ISSN：1520-6041
文摘
The reactions of radicals [Mo2Cp2(
-CO)2(CO)2(-L2)](BAr'4) [Cp = 
chars/eta.gif" BORDER=0 >5-C5H5; L2 = Ph2PCH2PPh2 (dppm), Me2PCH2PMe2 (dmpm)] with an excess of the 1-alkynes HCCR (R = p-tol,tBu, CO2Me) give two main type of products, the paramagnetic alkyne-bridged complexes[Mo2Cp2(-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HC2R)(CO)2(-L2)](BAr'4) and the diamagnetic dicarbonyls [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >3-HCC(R)C(OH)}(CO)2(-L2)](BAr'4), which result from coupling of the incoming alkyne anda hydroxycarbyne ligand. The reaction of [Mo2Cp2(-CO)2(CO)2(-dmpm)](BAr'4) withHCC(CO2Me) gave additionally the compound [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2,chars/kappa.gif" BORDER=0 >-C(CO2Me)CPMe2CH2PMe2}(CO)3](BAr'4), resulting from coupling of the diphosphine and the alkyne. The relativeamounts of the products in the above reactions were found to be strongly dependent on thealkyne used. The compounds [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >3-HCC(R)C(OH)}(CO)2(-L2)](BAr'4) (R = tBu,CO2Me) experience overall deprotonation by reaction with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), to give the corresponding neutral species [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HCC(R)C(O)}(CO)2(-L2)]through an unexpected reduction/dehydrogenation pathway. This overall deprotonation isreversible, and reaction of the neutral complexes with HBF4·OEt2 occurs specifically at theoxygen atom of the acyl group to give the starting cations as BF4- salts. Unexpectedly, thereduction of the alkyne-bridged radicals [Mo2Cp2(-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HC2R)(CO)2(-L2)](BAr'4) with Naamalgam gave unstable paramagnetic derivatives that could not be characterized. Thecomplexes [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >3-HCC(tBu)C(OH)}(CO)2(-dmpm)](BAr'4), [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2,chars/kappa.gif" BORDER=0 >-C(CO2Me)CPMe2CH2PMe2}(CO)3](BAr'4), and [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HCC(CO2Me)C(O)}(CO)2(-dppm)]were characterized through single-crystal X-ray diffraction studies. The solution structuresof all new compounds are analyzed in the light of IR and NMR spectra, and plausible reactionpathways are proposed in order to explain the formation of the products isolated.
-CO)2(CO)2(-L2)](BAr'4) [Cp = chars/eta.gif" BORDER=0 >5-C5H5; L2 = Ph2PCH2PPh2 (dppm), Me2PCH2PMe2 (dmpm)] with an excess of the 1-alkynes HCCR (R = p-tol,tBu, CO2Me) give two main type of products, the paramagnetic alkyne-bridged complexes[Mo2Cp2(-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HC2R)(CO)2(-L2)](BAr'4) and the diamagnetic dicarbonyls [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >3-HCC(R)C(OH)}(CO)2(-L2)](BAr'4), which result from coupling of the incoming alkyne anda hydroxycarbyne ligand. The reaction of [Mo2Cp2(-CO)2(CO)2(-dmpm)](BAr'4) withHCC(CO2Me) gave additionally the compound [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2,chars/kappa.gif" BORDER=0 >-C(CO2Me)CPMe2CH2PMe2}(CO)3](BAr'4), resulting from coupling of the diphosphine and the alkyne. The relativeamounts of the products in the above reactions were found to be strongly dependent on thealkyne used. The compounds [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >3-HCC(R)C(OH)}(CO)2(-L2)](BAr'4) (R = tBu,CO2Me) experience overall deprotonation by reaction with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene), to give the corresponding neutral species [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HCC(R)C(O)}(CO)2(-L2)]through an unexpected reduction/dehydrogenation pathway. This overall deprotonation isreversible, and reaction of the neutral complexes with HBF4·OEt2 occurs specifically at theoxygen atom of the acyl group to give the starting cations as BF4- salts. Unexpectedly, thereduction of the alkyne-bridged radicals [Mo2Cp2(-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HC2R)(CO)2(-L2)](BAr'4) with Naamalgam gave unstable paramagnetic derivatives that could not be characterized. Thecomplexes [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >3-HCC(tBu)C(OH)}(CO)2(-dmpm)](BAr'4), [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2,chars/kappa.gif" BORDER=0 >-C(CO2Me)CPMe2CH2PMe2}(CO)3](BAr'4), and [Mo2Cp2{-chars/eta.gif" BORDER=0 >2:chars/eta.gif" BORDER=0 >2-HCC(CO2Me)C(O)}(CO)2(-dppm)]were characterized through single-crystal X-ray diffraction studies. The solution structuresof all new compounds are analyzed in the light of IR and NMR spectra, and plausible reactionpathways are proposed in order to explain the formation of the products isolated.