A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä

Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand: Synthesis, characterization and oxotransfer activity




TekijätHossain MK, Kohntopp A, Haukka M, Richmond MG, Lehtonen A, Nordlander E

KustantajaPERGAMON-ELSEVIER SCIENCE LTD

Julkaisuvuosi2020

JournalPolyhedron

Tietokannassa oleva lehden nimiPOLYHEDRON

Lehden akronyymiPOLYHEDRON

Artikkelin numeroUNSP 114312

Vuosikerta178

Sivujen määrä8

ISSN0277-5387

DOIhttps://doi.org/10.1016/j.poly.2019.114312

Rinnakkaistallenteen osoitehttps://research.utu.fi/converis/portal/detail/Publication/46957078


Tiivistelmä
Reaction of [MoO2Cl2(dmso)(2)] with the tetradentate O2N2 donor ligand papy [H(2)papy = N-(2-hydroxybenzyl)-N-(2-picolyl)glycine] leads to formation of the dioxomolybdenum(VI) complex [MoO2(papy)] (1) as a mixture of cis and trans isomers. Recrystallization from methanol furnishes solid cis-1, whereas the use of a dichloromethane-hexane mixture allows for the isolation of the trans-1 isomer. Both isomers have been structurally characterized by X-ray crystallography and the energy difference between the isomeric pair has been investigated by electronic structure calculations. Optimization of two configurational isomers in the gas phase predicts the trans isomer to lie 2.5 kcal/mol lower in energy (DG) than the cis isomer, which is inconsistent with the solution NMR data in d(3)-MeCN that exhibit a K-eq of ca. 3 at 298 K for the trans reversible arrow cis equilibrium. The DFT-computed energy difference is significantly improved (K-eq = 5.4) by the inclusion of the MeCN solvent using the polarization continuum model (PCM). Density functional calculations reveal that the isomerization proceeds via a Ray-Dutt twist mechanism with a barrier of 14.5 kcal/mol, which is in accordance with the H-1 NMR spectral data and the rapid equilibration of these isomers in solution. The catalytic reactivity of [MoO2(papy)] in the epoxidation of ciscyclooctene is described, as well as its ability to effect oxo transfer from DMSO to PPh3. (C) 2019 Elsevier Ltd. All rights reserved.

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