ИСТИНА |
Войти в систему Регистрация |
|
ФНКЦ РР |
||
Herein we report our studies of the mercury(0) reactions with palladacycles con¬tai¬ning highly-protected P,C-donor ligands. We have chosen as examples well-known cyclopalladated derivatives of tris-ortho-tolylphosphine, namely -acetate (1a) and -chloride (1b) P,C-dimers. In contrast to all C,N-dimers, the P,C-dimers 1a,b do not re¬act with Hg(0) at room tempera¬tu¬re due to effective Pd(II) protection by strong P,C-chelated ligand. However, at high temperature, the complete conversion of the cyclo¬palladated dimers 1a,b into the benzylmercurials 2a,b was observed. The structure of isolated organomercurial 2b was confirmed by 1H, 13C{1H}, 31P{1H}, and 199Hg{1H} NMR spectroscopy, X-ray diffraction studies, and DFT calculation. The highest stability to the mercury(0) impact was observed in the case of the cyclopalladated phosphite dimer [{(2P,C-L)Pd(-Cl)}] (3) (L– = 2,4-tBu2C6H4), known as the Bedford’s precatalyst. Even after its very long boiling in toluene with a 330-fold excess of Hg(0), we did not find traces of the expected arylmercurial [(2P,C-L)HgCl]. The extremely high stability of the ortho-palladated phosphite dimer 3 compared to its cyclopalladated phosphine analog 1b can be explained by the greater π-acidity of its P-donor, the lower σ-basicity of the ortho-palladated carbon atom, and the more electron-deficient palladium center.
№ | Имя | Описание | Имя файла | Размер | Добавлен |
---|---|---|---|---|---|
1. | Полный текст | текст тезиса | Book_of_Abstract-Gorunova.pdf | 1,9 МБ | 10 декабря 2019 [GorunovaON] |