178211-50-2Relevant academic research and scientific papers
Substitution and oxidative addition reactions of the monoolefin complex Rh(acac)(cyclooctene)(PCy3) including the X-ray structure analyses of Rh(acac)(PCy3)2 and [Rh(acac){(E)-CH=CHCy}(PCy3)2]BF4
Esteruelas, Miguel A.,Lahoz, Fernando J.,O?ate, Enrique,Oro, Luis A.,Rodríguez, Laura,Steinert, Paul,Werner, Helmut
, p. 3436 - 3444 (2008/10/08)
The olefin complex Rh(acac)(cyclooctene)(PCy3) (2), which is formed from Rh(acac)-(cyclooctene)2 (1) and PCy3 in nearly quantitative yield, reacts with CO and alkynes RC≡CR by ligand displacement to give Rh(acac)(CO)(PCy3) (3) and Rh(acac)(η2-RC≡CR)(PCy3) [R = CO2Me (4), Ph (5)], respectively. The bis(phosphine) compound Rh(acac)(PCy3)2 (6) cannot be prepared directly from 2 and excess PCy3 but via Rh(acac)(η2-HC≡CCO2Me)(PCy3) (7) as intermediate. The X-ray crystal structure analysis of 6 reveals that the rhodium is coordinated in a distorted square-planar manner with O-Rh-O and P-Rh-P bond angles of 85.9(1) and 105.63(4)°. Compound 2 reacts with H2 in the presence of PCy3 to yield Rh-(acac)H2(PCy3)2 (8) and with HC≡CR/PCy3 to give Rh(acac)H(C≡CR)(PCy3)2 [R = Ph (9), Cy (10), SiMe3 (11)]. On treatment of 10 and 11 with HBF4·OEt2, the cationic alkenylrhodium(III) derivatives [Rh(acac){(E)-CH=CHCy}(PCy3)2]BF4 (12) and [Rh(acac)(CH=CH2)-(PCy3)2]BF4 (13) are obtained. Labeling experiments using DBF4·OEt2 illustrate that the deuterium is found at the β-C carbon atom of the alkenyl ligand. Both 12 and [Rh(acac)-{(E)-CH=CDCy}(PCy3)2]BF4 (12-d1) react with NEt3 to regenerate 10. The structure of 12 was determined by X-ray analysis. The coordination geometry around the metal center can be rationalized as a square pyramid with the alkenyl group in the apical position.
