900152-27-4Relevant academic research and scientific papers
Synthesis of chalcogenidoimidodiphosphinato-RhI complexes and DFT investigation of their catalytic activation in olefin hydroformylation
Grigoropoulos, Alexios,Maganas, Dimitrios,Symeonidis, Dimitrios,Giastas, Petros,Cowley, Andrew R.,Kyritsis, Panayotis,Pneumatikakis, Georgios
, p. 1170 - 1183 (2013/04/10)
The synthesis and spectroscopic characterization of [Rh{R 2P(S)NP(S)R2-S,S′}(cod)] [cod = 1,5-cyclooctadiene; R = Ph (1), iPr (4)], [Rh{Ph2P(S)NP(S)Ph2-S,S′}(CO) 2] (2) and [Rh{Ph2P(S)NP(S)Ph2-S,S′}(CO) (PPh3)] (3) is described. The crystal structures of complexes 1 and 3 are also presented. The synthesized RhI complexes are essentially not catalytically active against olefin hydroformylation, in contrast to the previously reported complex [Rh{Ph2P(O)NPPh2-P,O}(CO) (PPh3)] (6). Differences in the catalytic activity were interpreted with the aid of a well-defined DFT-based protocol involving relativistic effects and dispersion correction. The steric and electronic effects of the Rh I coordination environment with respect to their activation by H 2 are discussed. The results demonstrate that the presence of the more electronegative oxygen atom in the RhI coordination sphere polarizes the H-H bond and promotes its heterolytic cleavage, thereby leading to the formation of a RhI-monohydride complex in which the oxygen atom of the ligand is protonated. The different catalytic properties of mono- and dichalcogenidoimidodiphosphinato-RhI complexes have been investigated through a combined experimental and computational approach. The results indicate that catalytic activation proceeds by means of the ligand-assisted heterolytic cleavage of H2. Copyright
