Rhenium−Platinum Mixed-Metal Spiked-Triangle Clusters. Synthesis and X-ray Characterization of the Cluster Anions [Re2Pt(μ-H)2(CO)9{Re(CO)5}]- and [Re2Pt(μ-H)2(CO)9{HRe2(CO)9}]

Autor: Gianfranco Ciani, Mirka Bergamo, Giuseppe D'Alfonso, Massimo Moret, Tiziana Beringhelli, Angelo Sironi
Rok vydání: 1996
Předmět:
Zdroj: Organometallics. 15:1637-1644
ISSN: 1520-6041
0276-7333
DOI: 10.1021/om9507080
Popis: The spiked-triangle cluster [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 9}[Re(CO){sub 5}]] B@ (1), which contains a HRe(CO){sub 5} molecule bound to the Pt vertex of a Re{sub 2}Pt triangle, reacts with methanolic NEt{sub 4}OH to give the red anion [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 9}[Re(CO){sub 5}]]{sup -} (2), whose structure has been determined by single-crystal X-ray analysis of its NEt{sub 4}{sup +} salt. NMR monitoring showed the intermediate formation of a carbomethoxy derivative 3, arising from the attack of OMe{sup -} on a carbonyl of the HRe(CO){sub 5} group. The deprotonation of 1 can be performed also by a base as weak as pyridine. The anion 2 in solution is thermally unstable, and at room temperature it gives rise to complex mixtures. The main component has been identified, by X-ray analysis of its NEt{sub 4}{sup +} salt, as the anion [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 9}[HRe{sub 2}(CO){sub 9}]]RB{sup -} (4), containing a HRe{sub 2}(CO){sub 9}{sup +} complex bound to the Pt vertex of a Re{sub 2}Pt triangle, through a Re({mu}-H)Pt bond. The anions 2 and 4 are better obtained by treating [Re{sub 2}Pt({mu}-H){sub 2}(CO){sub 8}(COD)] (COD=1,5-cyclooctadiene) with [Re(CO){sub 5}]{sup -} or [HRe{sub 2}(CO){sub 9}]{sup -}, respectively, in the presence of CO. Experiments have been performed to clarifymore » the origin of the [HRe{sub 2}(CO){sub 9}]{sup -} fragment bound to Pt in 4. The reaction between free [HRe(CO){sub 5}] and [Re(CO){sub 5}]{sup -} produces in high yields the anion [HRe{sub 2}(CO){sub 9}]{sup -}, but this one does not displace Re(CO){sub 5}{sup -} from 2. The reaction between [Re(CO){sub 5}]{sup -} and the complex 1 gives instantaneously the anion 2. No reaction occurs upon treatment of the anion 2 with [HRe(CO){sub 5}]. Variable-temperature NMR has revealed the occurrence in both the anions 3 and 4 of an intramolecular dynamic process equalizing the two hydrides bound to the Pt atom, with E{sub a}=70(1) and 74(7) kJ/mol, respectively.« less
Databáze: OpenAIRE
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