Chiral-at-Tungsten Dioxo Complexes─A Computational Study on Inhibiting Racemization

George Dhimba; Alfred Muller; Koop Lammertsma

doi:10.1021/acs.inorgchem.5c01280

Chiral-at-Tungsten Dioxo Complexes─A Computational Study on Inhibiting Racemization

George Dhimba
, Alfred Muller
, Koop Lammertsma

Chemical Sciences

Research output: Contribution to journal › Article › peer-review

Abstract

Chiral cis-WO₂(acac)₂ and cis-WO₂(nacnac)₂ complexes racemize via four pathways according to DFT calculations at ωB97X-D/6-311+G(2d,f) with LANL2DZ for W and with inclusion of acetonitrile solvent. Steric congestion by N-Me and N-Ph substitution of the two nacnac ligands has a substantial geometrical impact and raises the barriers for all pathways. Despite this, even all N-Me and all N-Ph substituted derivatives of cis-WO₂(nacnac)₂ have the same four channels for racemization. For each of these complexes, the Dhimba-Muller-Lammertsma (DML) twist is preferred over the Conte-Hippler (CH) twist and significantly favored over the established Bailar (B) and Ray-Dutt (RD) twists. The favored DML barrier for WO₂(nacnac)₂^Ph4 has a large estimated ΔG barrier of 25.7 kcal/mol, suggesting it to be a viable chiral-at-tungsten complex for asymmetric catalysis.

Original language	English
Pages (from-to)	13569-13576
Number of pages	8
Journal	Inorganic Chemistry
Volume	64
Issue number	27
DOIs	https://doi.org/10.1021/acs.inorgchem.5c01280
Publication status	Published - 14 Jul 2025

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

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10.1021/acs.inorgchem.5c01280

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title = "Chiral-at-Tungsten Dioxo Complexes─A Computational Study on Inhibiting Racemization",

abstract = "Chiral cis-WO2(acac)2 and cis-WO2(nacnac)2 complexes racemize via four pathways according to DFT calculations at ωB97X-D/6-311+G(2d,f) with LANL2DZ for W and with inclusion of acetonitrile solvent. Steric congestion by N-Me and N-Ph substitution of the two nacnac ligands has a substantial geometrical impact and raises the barriers for all pathways. Despite this, even all N-Me and all N-Ph substituted derivatives of cis-WO2(nacnac)2 have the same four channels for racemization. For each of these complexes, the Dhimba-Muller-Lammertsma (DML) twist is preferred over the Conte-Hippler (CH) twist and significantly favored over the established Bailar (B) and Ray-Dutt (RD) twists. The favored DML barrier for WO2(nacnac)2Ph4 has a large estimated ΔG barrier of 25.7 kcal/mol, suggesting it to be a viable chiral-at-tungsten complex for asymmetric catalysis.",

author = "George Dhimba and Alfred Muller and Koop Lammertsma",

note = "Publisher Copyright: {\textcopyright} 2025 The Authors. Published by American Chemical Society.",

year = "2025",

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day = "14",

doi = "10.1021/acs.inorgchem.5c01280",

language = "English",

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T1 - Chiral-at-Tungsten Dioxo Complexes─A Computational Study on Inhibiting Racemization

AU - Dhimba, George

AU - Muller, Alfred

AU - Lammertsma, Koop

PY - 2025/7/14

Y1 - 2025/7/14

N2 - Chiral cis-WO2(acac)2 and cis-WO2(nacnac)2 complexes racemize via four pathways according to DFT calculations at ωB97X-D/6-311+G(2d,f) with LANL2DZ for W and with inclusion of acetonitrile solvent. Steric congestion by N-Me and N-Ph substitution of the two nacnac ligands has a substantial geometrical impact and raises the barriers for all pathways. Despite this, even all N-Me and all N-Ph substituted derivatives of cis-WO2(nacnac)2 have the same four channels for racemization. For each of these complexes, the Dhimba-Muller-Lammertsma (DML) twist is preferred over the Conte-Hippler (CH) twist and significantly favored over the established Bailar (B) and Ray-Dutt (RD) twists. The favored DML barrier for WO2(nacnac)2Ph4 has a large estimated ΔG barrier of 25.7 kcal/mol, suggesting it to be a viable chiral-at-tungsten complex for asymmetric catalysis.

AB - Chiral cis-WO2(acac)2 and cis-WO2(nacnac)2 complexes racemize via four pathways according to DFT calculations at ωB97X-D/6-311+G(2d,f) with LANL2DZ for W and with inclusion of acetonitrile solvent. Steric congestion by N-Me and N-Ph substitution of the two nacnac ligands has a substantial geometrical impact and raises the barriers for all pathways. Despite this, even all N-Me and all N-Ph substituted derivatives of cis-WO2(nacnac)2 have the same four channels for racemization. For each of these complexes, the Dhimba-Muller-Lammertsma (DML) twist is preferred over the Conte-Hippler (CH) twist and significantly favored over the established Bailar (B) and Ray-Dutt (RD) twists. The favored DML barrier for WO2(nacnac)2Ph4 has a large estimated ΔG barrier of 25.7 kcal/mol, suggesting it to be a viable chiral-at-tungsten complex for asymmetric catalysis.

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DO - 10.1021/acs.inorgchem.5c01280

M3 - Article

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SN - 0020-1669

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JO - Inorganic Chemistry

JF - Inorganic Chemistry

IS - 27

ER -

Chiral-at-Tungsten Dioxo Complexes─A Computational Study on Inhibiting Racemization

Abstract

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