Renaissance of the entatic state principle

Stanek, Julia; Hoffmann, Alexander; Herres‐Pawlis, Sonja

doi:10.1016/j.ccr.2018.03.009

Cited by 56 publications

(61 citation statements)

References 104 publications

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“…However, given the general nature of this description, it is being extended to other scenarios, including photochemistry and catalysis. [85][86][87][88][89] Strain effects have also been discussed in the context of both ground and excited states and their contributions to the coherence properties in solid state qubits (e.g, vacancies in diamond). [10][11][12]90 Thus, engineering ligand field strain and rigidity into covalent environments will be useful for advancing the geometric and electronic structural contributions to the quantum coherence of transition metal complexes, and the model outlined here can guide these future investigations.…”

Section: Ligand Field Strain In Qubitsmentioning

confidence: 99%

The Dynamic Ligand Field of a Molecular Qubit: Decoherence Through Spin–Phonon Coupling

Mirzoyan¹,

Hadt²

2019

Preprint

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Quantum coherence of S = 1/2 transition metal-based quantum bits (qubits) is strongly influenced by the magnitude of spin–phonon coupling. While this coupling is recognized as deriving from dynamic distortions about the first coordination sphere of the metal, a general model for understanding and quantifying ligand field contributions has not been established. Here we derive a general ligand field theory model to describe and quantify the nature of spin–phonon coupling terms in S = 1/2 transition metal complexes. We show that the coupling term for a given vibrational mode is governed by: 1) the magnitude of the metal-based spin–orbit coupling constant, 2) the magnitude and gradient in the ligand field excited state energy, and 3) dynamic relativistic nephelauxetic contributions reflecting the magnitude and gradient in the covalency of the ligand–metal bonds. From an extensive series of density functional theory (DFT) and time-dependent DFT (TDDFT) calculations calibrated to a range of experimental data, spin–phonon coupling terms describing minimalistic D4h/D2d [CuCl4]2- and C4v [VOCl4]2- complexes translate to and correlate with experimental quantum coherence properties observed for Cu(II)- and V(IV)-based molecular qubits with different ligand sets, geometries, and coordination numbers. While providing a fundamental framework and means to benchmark current qubits, the model and methodology described herein can be used to screen any S = 1/2 molecular qubit candidate and guide the discovery of room temperature coherent materials for quantum information processing.

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Section: Ligand Field Strain In Qubitsmentioning

confidence: 99%

The Dynamic Ligand Field of a Molecular Qubit: Decoherence Through Spin–Phonon Coupling

Mirzoyan¹,

Hadt²

2019

Preprint

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“…To fulfill these stringent criteria of natural resources, metalloenzymes have evolved reactivity-enhancing strategies aimed at performing such difficult transformations through more favorable thermodynamic pathways. The entatic state concept stems from the observation that single molecule coordination complexes designed as metalloenzymes models often fail to exhibit properties similar to the natural metalloenzymatic active sites (Vallee and Williams, 1968;Williams, 1971Williams, , 1995Stanek et al, 2018). It was thus suggested that secondary and tertiary structures induced by amino acid-based side chains in proteins provide distortions in the coordinative environment that endow the metal center with enhanced reactivity, to which Vallé e and Williams refer as ''a catalytically poised state'' (Vallee and Williams, 1968).…”

Section: Introductionmentioning

confidence: 99%

Optimizing Group Transfer Catalysis by Copper Complex with Redox-Active Ligand in an Entatic State

et al. 2020

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Metalloenzymes use earth-abundant non-noble metals to perform high-fidelity transformations in the biological world. To ensure chemical efficiency, metalloenzymes have acquired evolutionary reactivity-enhancing tools. Among these, the entatic state model states that a strongly distorted geometry induced by ligands around a metal center gives rise to an energized structure called entatic state, strongly improving the reactivity. However, the original definition refers both to the transfer of electrons or chemical groups, whereas the chemical application of this concept in synthetic systems has mostly focused on electron transfer, therefore eluding chemical transformations. Here we report that a highly strained redox-active ligand enables a copper complex to perform catalytic nitrogenand carbon-group transfer in as fast as 2 min, thus exhibiting a strong increase in reactivity compared with its unstrained analogue. This report combines two reactivity-enhancing features from metalloenzymes, entasis and redox cofactors, applied to group-transfer catalysis.

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“…The right-hand panel is from a 2018 paper in Coordination Chemistry Reviews by the group of Herres-Pawlis entitled ''Renaissance of the entatic state principle''. 17 The figure is clearly inspired by the early work, but where Williams remarks that ''No special significance is attached to the coincidental placing of the transition states'', in 2018 this becomes: ''The reactant and product energies as well as the degree of energization are arbitrarily chosen. Now we have a problem: the raising of energies may be 'arbitrary', but where do they come from in the absence of a macromolecule with a wide conformational distribution?…”

Section: Bootstrapping Free Coordination Compounds Into Entatic Statesmentioning

confidence: 99%

“…Numerous reports have appeared over the last two decades on presumed entatic states in copper coordination compounds. 17 It is beyond our scope to give a comprehensive evaluation of these studies, but we look at a few salient examples of particular relevance to our present discourse. Rorabacher's group claims to have identified ''A definitive example of a geometric entatic state effect'' when they find that in the combination of Cu(II)/ Cu(I) with a particular macrocyclic ligand providing NNSSS ligation the geometries of the two redox states are nearly identical and the electron self-exchange rate is very high and on a par with electron-transferring blue copper proteins.…”

Section: Entatic States Ascribed To Coordination Complexesmentioning

confidence: 99%