Neal P. Mankad*, Sylvain Roland, Matthieu Sollogoub* and Jeremiah E. Stevens,
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引用次数: 0
Abstract
Although secondary coordination sphere effects on catalytic active sites are widely appreciated, the influence of such interactions on (hetero)binuclear active sites has not been examined comprehensively. Here, the influence of cyclodextrin encapsulation on the (NHC)Cu-FeCp(CO)2 moiety, which is known to be catalytically active in several transformations, is analyzed in detail. Compared to free (NHC)CuFp complexes (Fp = FeCp(CO)2), encapsulated (NHC)CuFp complexes were found to shift from resembling Fe(0) toward having Fe(II) character according to Mössbauer and IR spectroscopies. According to DFT modeling, this change in electronic structure is correlated to the pyramidalization of the Fp fragment away from a planar orientation and to the disruption of semibridging CO interactions typically found in (NHC)CuFp complexes. The latter change can be attributed, in part, to the presence of contra-electrostatic C–H···Cu anagostic interactions that outcompete semibridging Cu···CO interactions due to geometric constraints. These combined factors result in Fe(II)-like substitution reactivity of one of the CO ligands that is enabled only within the supramolecular architecture. The data presented herein provide understanding of how (hetero)binuclear reaction centers, especially those involving CO ligands, are influenced by partially covalent interactions from beyond the primary coordination sphere.
期刊介绍:
Organometallics is the flagship journal of organometallic chemistry and records progress in one of the most active fields of science, bridging organic and inorganic chemistry. The journal publishes Articles, Communications, Reviews, and Tutorials (instructional overviews) that depict research on the synthesis, structure, bonding, chemical reactivity, and reaction mechanisms for a variety of applications, including catalyst design and catalytic processes; main-group, transition-metal, and lanthanide and actinide metal chemistry; synthetic aspects of polymer science and materials science; and bioorganometallic chemistry.