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Benyzl Alcohol Dehydrogenative Coupling Catalyzed by Defined Mn and Re PNP Pincer Complexes – A Computational Mechanistic Study
Author(s) -
Wei Zhihong,
de Aguirre Adiran,
Junge Kathrin,
Beller Matthias,
Jiao Haijun
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800674
Subject(s) - chemistry , pincer movement , catalysis , coordination sphere , pincer ligand , dehydrogenation , medicinal chemistry , hydride , outer sphere electron transfer , stereochemistry , density functional theory , ligand (biochemistry) , computational chemistry , crystallography , hydrogen , organic chemistry , ion , crystal structure , biochemistry , receptor
Density functional theory computations have been carried out to investigate the base free acceptor‐less dehydrogenative coupling of benzyl alcohol to benzyl benzoate catalyzed by defined Mn and Re PNP pincer amido M(CO) 2 (PNP) and amino H M(CO) 2 (PN H P) complexes [M = Mn, Re; PNP = N{CH 2 CH 2 P(isopropyl) 2 } 2 ]. Benchmark calculations show that B3PW91 have the best and closest agreement with the experiments than DLPNO‐CCSD(T). Within all proposed elementary steps, the non‐innocent outer‐sphere mechanism incorporating the amido complex and the N–H bond is more kinetically favored than the innocent outer‐sphere mechanism without the amido complex as well as the inner‐sphere mechanism via the de‐coordination of one phosphine ligand to create a vacant site for β‐hydride elimination. The dehydrogenation of hemiacetal to ester represents the rate‐determining step. Both Mn and Re‐based catalysts have close free energy barriers and similar catalytic activity. However, the computed apparent barrier is overestimated on the basis of the experimentally determined TOF for the Mn‐based complexes.