| ESI-MS is a technique that allows the ions present in solution to be transferred into the gas phase, that has proved to be a soft ionization method that keeps any weakly uncovalent bound in a complex and offers the complete information of the structure. With whese advantages, ESI has increasingly popular as an analytical tool in organometallic chemistry. As a speed and sensitivity analytical technique, it has been employed to catch active species and study mechanistic paths of reactions in combination with tandem mass spectrometry (MS/MS), IR and NMR. In this thesis, the stability of the SalenCo(â…¢)X complexes in two different reactions were investigated by ESI-MS/MS.Two different SalenCo(â…¢)X, complexes 1 and 2, with 1,5,7-triabicyclo[4.4.0] dec-5-ene (designated as TBD, a sterically organic base) anchored on the ligand framework has been characterized by ESI-MS(complex 1 contains one methylene that connects TBD with the ligand; while TBD is anchored by three methylene units to the ligand in complex 2). Then the stability of complexes 1 of and 2 in the reactions with epoxides had been studied by means of collision induced dissociation of MS/MS. The experimental results show that complex 1 completely transfers to inactive Co(â…¡), so it is inactive for the copolymerization of carbon dioxide and propylene oxide (PO). But ESI-MS can easily detect a the ring-opening product in the reaction of 2/PO which helps to stablize the active Co(â…¢) species. So complex 2 has highly catalytic active for the copolymerization. At last, the copolymerization of carbon dioxide and PO was done to prove the accuracy of the inference from ESI-MS.In view of the mechanism of the hydrolytic kinetic resolution (HKR) of racemic terminal epoxides catalyzed by SalenCo(â…¢)X is not clear, a new catalyst, SalenCo(â…¢)OAc, was presented. Then ESI-MS monitored the HKR of racemic terminal epoxides catalyzed by it The results showed that Co(â…¡) complex appeard in the reaction and became more and more with the reaction going on. The appearance of Co(â…¡) complex was restrained in the presence of HOAc, while the condition of no oxygen was in favor of the appearance of Co(â…¡) complex. In the end, the mechanism of the hydrolytic kinetic resolution of racemic terminal epoxides and the reason of the appearance of Co(â…¡) complex was proposed. |
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