A1 Journal article (refereed)
Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand : Synthesis, characterization and oxotransfer activity (2020)


Hossain, Md Kamal; Köhntopp, Anja; Haukka, Matti; Richmond, Michael G.; Lehtonen, Ari; Nordlander, Ebbe (2020). Cis- and trans molybdenum oxo complexes of a prochiral tetradentate aminophenolate ligand : Synthesis, characterization and oxotransfer activity. Polyhedron, 178, 114312. DOI: 10.1016/j.poly.2019.114312


JYU authors or editors


Publication details

All authors or editors: Hossain, Md Kamal; Köhntopp, Anja; Haukka, Matti; Richmond, Michael G.; Lehtonen, Ari; Nordlander, Ebbe

Journal or series: Polyhedron

ISSN: 0277-5387

eISSN: 1873-3719

Publication year: 2020

Volume: 178

Article number: 114312

Publisher: Elsevier

Publication country: United Kingdom

Publication language: English

DOI: http://doi.org/10.1016/j.poly.2019.114312

Open Access: Publication channel is not openly available

Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/67374


Abstract

Reaction of [MoO2Cl2(dmso)2] with the tetradentate O2N2 donor ligand papy [H2papy = 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 (ΔG) than the cis isomer, which is inconsistent with the solution NMR data in d3-MeCN that exhibit a Keq of ca. 3 at 298 K for the trans⇌cis equilibrium. The DFT-computed energy difference is significantly improved (Keq = 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 1H NMR spectral data and the rapid equilibration of these isomers in solution. The catalytic reactivity of [MoO2(papy)] in the epoxidation of cis-cyclooctene is described, as well as its ability to effect oxo transfer from DMSO to PPh3.


Free keywords: Oxo Atom Transfer; epoxidation; tripodal ligand; variable temperature NMR; computational modelling


Contributing organizations


Ministry reporting: Yes

Reporting Year: 2020

Preliminary JUFO rating: 1


Last updated on 2020-18-08 at 13:32