The effect of coordination of alkanes, Xe and CO2 (η1-OCO) on changes in spin state and reactivity in organometallic chemistry: a combined experimental and theoretical study of the photochemistry of CpMn(CO)3

Wu, Xue; Liu, Zhen; Murphy, Thomas S.; Sun, Xue Z.; Hanson-Heine, Magnus W. D.; Towrie, Michael; Harvey, Jeremy N.; George, Michael W.

Abstract

A combined experimental and theoretical study is presented of several ligand addition reactions of the triplet fragment 3CpMn(CO)2 formed upon photolysis of CpMn(CO)3. Experimental data are provided for reactions in n-heptane and perfluoromethylcyclohexane (PFMCH), as well as in PFMCH doped with C2H6, Xe and CO2. In PFMCH we find that the conversion of 3CpMn(CO)2 to 1CpMn(CO)2(PFMCH) is much slower (τ = 18 (±3) ns) than the corresponding reactions in conventional alkanes (τ = 111 (±10) ps). We measure the effect of the coordination ability by doping PFMCH with alkane, Xe and CO2; these doped ligands form the corresponding singlet adducts with significantly variable formation rates. The reactivity as measured by the addition timescale follows the order 1CpMn(CO)2(C5H10) (τ = 270 (±10) ps) > 1CpMn(CO)2Xe (τ = 3.9 (±0.4) ns) ∼ 1CpMn(CO)2(CO2) (τ = 4.7 (±0.5) ns) > 1CpMn(CO)2(C7F14) (τ = 18 (±3) ns). Electronic structure theory calculations of the singlet and triplet potential energy surfaces and of their intersections, together with non-adiabatic statistical rate theory, reproduce the observed rates semi-quantitatively. It is shown that triplet adducts of the ligand and 3CpMn(CO)2 play a role in the kinetics, and account for the variable timescales observed experimentally.

Citation

Wu, X., Liu, Z., Murphy, T. S., Sun, X. Z., Hanson-Heine, M. W. D., Towrie, M., Harvey, J. N., & George, M. W. (2019). The effect of coordination of alkanes, Xe and CO2 (η1-OCO) on changes in spin state and reactivity in organometallic chemistry: a combined experimental and theoretical study of the photochemistry of CpMn(CO)3. Faraday Discussions, 220, 86-104. https://doi.org/10.1039/c9fd00067d

• Journal Article Type: Article
• Acceptance Date: Jul 4, 2019
• Online Publication Date: Oct 14, 2019
• Publication Date: Dec 2, 2019
• Deposit Date: Oct 28, 2019
• Publicly Available Date: Oct 15, 2020
• Journal: Faraday Discussions
• Print ISSN: 1359-6640
• Electronic ISSN: 1364-5498
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 220
• Pages: 86-104
• DOI: https://doi.org/10.1039/c9fd00067d
• Public URL: https://nottingham-repository.worktribe.com/output/2977300
• Publisher URL: https://pubs.rsc.org/en/content/articlelanding/2019/FD/C9FD00067D#!divAbstract
• Additional Information: : This document is Similarity Check deposited; : Supplementary Information; : Zhen Liu (ORCID); : Zhen Liu (ResearcherID); : Thomas S. Murphy (ORCID); : Jeremy N. Harvey (ORCID); : Jeremy N. Harvey (ResearcherID); : Michael W. George (ORCID); : Single-blind; : Received 13 May 2019; Accepted 4 July 2019; Advance Article published 14 October 2019
• Contract Date: Oct 28, 2019