| Autor: |
Adams, Harry, Bailey, Neil A., Blenkiron, Peter, Morris, Michael J. |
| Zdroj: |
Journal of the Chemical Society, Dalton Transactions; September 21, 2000, Vol. 2000 Issue: 18 p3074-3081, 8p |
| Abstrakt: |
Deprotonation of the secondary phosphine ligand in the complex [Mo(COMe)(CO)2(PPh2H)(η-C5H5)] 1 with DBU (1,8-diazabicyclo[5.4.0]undec-7-ene) at −78 °C followed by reaction with DMAD (dimethyl acetylenedicarboxylate, MeO2CC&z.tbd6;CCO2Me) afforded the vinylphosphine complex trans-[Mo(COMe)(CO)2{PPh2C(CO2Me)&z.dbd6;CHCO2Me}(η-C5H5)] 2a after protonation. The crystal structure of this compound confirms that the phosphine ligand is formed exclusively as the Z isomer. A similar reaction employing methyl propiolate afforded an analogous product [Mo(COMe)(CO)2(PPh2CH&z.dbd6;CHCO2Me)(η-C5H5)] 2b with complete regioselectivity but less stereoselectivity in that three isomers (trans-E, trans-Z and cis-E) are formed in a ratio of 9.4∶2.8∶1. Deprotonation of 1 at room temperature, which has previously been shown to form the anion [Mo(CO)2(PPh2COMe)Cp]− by migration of the acetyl group to phosphorus, followed by treatment with DMAD and rapid addition of acid produces the acryloyl complex [Mo{COC(CO2Me)&z.dbd6;CHCO2Me}(CO)(PPh2COMe)(η-C5H5)] 3a, accompanied by the chelating vinyl species [Mo{C(CO2Me)&z.dbd6;CHCOOMe}(CO)2(η-C5H5)] 4. A similar reaction with methyl propiolate gave [Mo(η3-COCH&z.dbd6;CHCO2Me)(CO)(PPh2COMe)(η-C5H5)] 3b but in this case the isomeric vinyl complex trans-[Mo(CH&z.dbd6;CHCO2Me)(CO)2(PPh2COMe)(η-C5H5)] 5 was formed as the minor product. Finally, deprotonation of 1 at room temperature followed by treatment with DMAD without subsequent addition of acid gives the metallacycle [Mo{PPh2COCH&z.dbd6;C(CO2Me)}(CO)2(η-C5H5)] 6. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
|
