Effect of the substituent on C–H activation catalyzed by a non-heme Fe(iv)O complex: a computational investigation of reactivity and hydrogen tunneling

Abstract

A density functional theory investigation has been presented here to address the C-H activation reactivity and the influence of quantum mechanical tunneling catalyzed by a non-heme iron(IV)-Oxo complex viz. [FeIVOdpaq-X]+...

Data-driven ligand field exploration of Fe(iv)–oxo sites for C–H activation

“…The octahedral complexes (1-15) have the largest range (13.97 kcal mol −1 ) and the most favorable δΔG ‡ values on average (−1.72 kcal mol −1 ). The κ 1 -trigonal bipyramidal complexes (16-29) and κ 4 -trigonal bipyramidal complexes (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) exhibit similar ranges of δΔG ‡ (10.40 and 10.18 kcal mol −1 , respectively). However, on average, the κ 1 -trigonal bipyramidal complexes experience a more negative δΔG ‡ than κ 4 -trigonal bipyramidal complexes (−1.47 and 0.68 kcal mol −1 , respectively), with the κ 4 complexes exhibiting the least favorable δΔG ‡ of any group.…”

“…In this study, we are introducing a database of 50 Fe(IV)-oxo complexes (Fig. 1) that include octahedral (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15), κ 1 -trigonal bipyramidal (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29), square pyramidal (30)(31)(32)(33)(34), and κ 4 -trigonal bipyramidal or tetradentate tripodal (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) molecular structu...…”

“…Cyclam and tetramethylated cyclams stabilize an S = 1 Fe(IV)-oxo, while many of the TMC and TMCO complexes have a transition state with a S = 2 spin state. The remaining complexes (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50) utilize tetradentate tripodal trenbased ligands. The TMG 3 tren ligand scaffold supports the notion that trigonal bipyramidal geometries can stabilize a high spin Fe(IV)-oxo and may lead to high HAA reactivity.…”

“…28 Computational studies have provided a comprehensive understanding of the electronic structure of the Fe(IV)-oxo site and its role in a wide variety of chemical reactions. [29][30][31][32][33][34][35][36][37] However, for the development of novel design strategies that lead to improved catalytic performance, a systematic exploration of a large number of molecular systems is mandatory. Previous studies range from the analysis of a small number of complexes for the development of structure-function relations 38 to high-throughput virtual screening of large molecular databases with the aid of quantum chemical methods and machine learning (ML).…”

A density functional theory analysis of the C–H activation reactivity of iron(iv)-oxo complexes with an ‘O’ substituted tetramethylcyclam macrocycle

“…Effects of N, O-substituted macrocycles on quantum mechanical tunneling and the H/D kinetic isotope effect have also been analysed. 36…”