Synthesis and solution fluxionality of rhenium(I ) carbonyl complexes of 2,4,6-tris(pyrazolyl)pyrimidines (L), [ReX(CO)3L](X = Cl, Br or I). Isolation and identification of the dinuclear complex [{ReBr(CO)3}2L]
| Autor: | Darren R. Noble, Keith G. Orrell, Vladimir Šik, Anthony G. Osborne, Andrew Gelling |
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| Rok vydání: | 1996 |
| Předmět: | |
| Zdroj: | J. Chem. Soc., Dalton Trans.. :3065-3070 |
| ISSN: | 1364-5447 0300-9246 |
| DOI: | 10.1039/dt9960003065 |
| Popis: | 2,4,6-Tris(pyrazolyl)pyrimidines reacted with pentacarbonylhalogenorhenium(I) complexes to form stable mixtures of bidentate, chelate complexes of types fac-[ReBr(CO)3(tpzp)],fac-[ReBr(CO)3(tmpzp)] and fac-[ReX(CO)3(tdmpzp)](X = Cl, Br or I) where tpzp = 2,4,6-tris(pyrazol-1-yl)pyrimidine, tmpzp = 2,4,6-tris(4-methylpyrazole-1-yl)pyrimidine and tdmpzp = 2,4,6-tris(3,5-dimethylpyrazol-1-yl)pyrimidine. In solution the complexes involving co-ordination with the 2-pyrazolyl ring nitrogen rather than the 4- or 6-pyrazolyl ring nitrogens strongly predominated (> 91%). Fluxional exchange between the two types of co-ordination species of tmpzp and tdmpzp was detected and measured quantitatively by dynamic NMR methods. Activation energies ΔG‡(298 K) for the fluxions were in the range 53–74 kJ mol–1. Dinuclear transition-metal complexes of type [{ReBr(CO)3}2L](L = tmpzp or tdmpzp) were also isolated. Structures were attributed to these nonfluxional complexes in solution. |
| Databáze: | OpenAIRE |
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