Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period

Weihao Zhu; Zhongwen Luo; Junqi Chen; Chang Liu; Lu Yang; Diane A. Dickie; Naiming Liu; Sen Zhang; Robert J. Davis; T. Brent Gunnoe

doi:10.1021/acscatal.9b01480

Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period

Weihao Zhu
, Zhongwen Luo
, Junqi Chen
, Chang Liu
, Lu Yang
, Diane A. Dickie
, Naiming Liu
, Sen Zhang
, Robert J. Davis
, T. Brent Gunnoe

Surface Chemistry & Catalysis Group

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

28 Scopus citations

Abstract

Studies of catalytic benzene alkenylation using different diimine ligated Rh(I) acetate complexes and Cu(OAc)₂ as the oxidant revealed statistically identical results in terms of activity and product selectivity. Under ethylene pressure, two representative diimine ligated rhodium(I) acetate complexes were demonstrated to exchange the diimine ligand with ethylene rapidly to form [Rh(μ-OAc)(Î•²-C₂H₄)₂]₂ and free diimine. Thus, it was concluded that diimine ligands are not likely coordinated to the active Rh catalysts under catalytic conditions. At 150 °C under catalytic conditions using commercial Cu(OAc)₂ as the oxidant, [Rh(μ-OAc)(Î•²-C₂H₄)₂]₂ undergoes rapid decomposition to form catalytically inactive and insoluble Rh species, followed by gradual dissolution of the insoluble Rh to form the soluble Rh, which is active for styrene production. Thus, the observed induction period under some conditions is likely due to the formation of insoluble Rh (rapid), followed by redissolution of the Rh (slow). The Rh decomposition process can be suppressed and the catalytically active Rh species maintained by using soluble Cu(II) oxidants or Cu(OAc)₂ that has been preheated. In such cases, an induction period is not observed.

Original language	English
Pages (from-to)	7457-7475
Number of pages	19
Journal	ACS Catalysis
Volume	9
Issue number	8
DOIs	https://doi.org/10.1021/acscatal.9b01480
State	Published - Aug 2 2019

Funding

This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division (DE-SC0000776).

Keywords

arene alkenylation
CH activation
diimine ligand
induction period
rhodium
styrene

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10.1021/acscatal.9b01480

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@article{de1deefe987d4e14993044e703a302fa,

title = "Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period",

abstract = "Studies of catalytic benzene alkenylation using different diimine ligated Rh(I) acetate complexes and Cu(OAc)2 as the oxidant revealed statistically identical results in terms of activity and product selectivity. Under ethylene pressure, two representative diimine ligated rhodium(I) acetate complexes were demonstrated to exchange the diimine ligand with ethylene rapidly to form [Rh(μ-OAc)({\^I}•2-C2H4)2]2 and free diimine. Thus, it was concluded that diimine ligands are not likely coordinated to the active Rh catalysts under catalytic conditions. At 150 °C under catalytic conditions using commercial Cu(OAc)2 as the oxidant, [Rh(μ-OAc)({\^I}•2-C2H4)2]2 undergoes rapid decomposition to form catalytically inactive and insoluble Rh species, followed by gradual dissolution of the insoluble Rh to form the soluble Rh, which is active for styrene production. Thus, the observed induction period under some conditions is likely due to the formation of insoluble Rh (rapid), followed by redissolution of the Rh (slow). The Rh decomposition process can be suppressed and the catalytically active Rh species maintained by using soluble Cu(II) oxidants or Cu(OAc)2 that has been preheated. In such cases, an induction period is not observed.",

keywords = "arene alkenylation, CH activation, diimine ligand, induction period, rhodium, styrene",

author = "Weihao Zhu and Zhongwen Luo and Junqi Chen and Chang Liu and Lu Yang and Dickie, \{Diane A.\} and Naiming Liu and Sen Zhang and Davis, \{Robert J.\} and Gunnoe, \{T. Brent\}",

note = "Publisher Copyright: Copyright {\textcopyright} 2019 American Chemical Society.",

year = "2019",

month = aug,

day = "2",

doi = "10.1021/acscatal.9b01480",

language = "English",

volume = "9",

pages = "7457--7475",

journal = "ACS Catalysis",

issn = "2155-5435",

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TY - JOUR

T1 - Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands

T2 - An Evaluation of the Role of Ligands and Induction Period

AU - Zhu, Weihao

AU - Luo, Zhongwen

AU - Chen, Junqi

AU - Liu, Chang

AU - Yang, Lu

AU - Dickie, Diane A.

AU - Liu, Naiming

AU - Zhang, Sen

AU - Davis, Robert J.

AU - Gunnoe, T. Brent

PY - 2019/8/2

Y1 - 2019/8/2

N2 - Studies of catalytic benzene alkenylation using different diimine ligated Rh(I) acetate complexes and Cu(OAc)2 as the oxidant revealed statistically identical results in terms of activity and product selectivity. Under ethylene pressure, two representative diimine ligated rhodium(I) acetate complexes were demonstrated to exchange the diimine ligand with ethylene rapidly to form [Rh(μ-OAc)(Î•2-C2H4)2]2 and free diimine. Thus, it was concluded that diimine ligands are not likely coordinated to the active Rh catalysts under catalytic conditions. At 150 °C under catalytic conditions using commercial Cu(OAc)2 as the oxidant, [Rh(μ-OAc)(Î•2-C2H4)2]2 undergoes rapid decomposition to form catalytically inactive and insoluble Rh species, followed by gradual dissolution of the insoluble Rh to form the soluble Rh, which is active for styrene production. Thus, the observed induction period under some conditions is likely due to the formation of insoluble Rh (rapid), followed by redissolution of the Rh (slow). The Rh decomposition process can be suppressed and the catalytically active Rh species maintained by using soluble Cu(II) oxidants or Cu(OAc)2 that has been preheated. In such cases, an induction period is not observed.

AB - Studies of catalytic benzene alkenylation using different diimine ligated Rh(I) acetate complexes and Cu(OAc)2 as the oxidant revealed statistically identical results in terms of activity and product selectivity. Under ethylene pressure, two representative diimine ligated rhodium(I) acetate complexes were demonstrated to exchange the diimine ligand with ethylene rapidly to form [Rh(μ-OAc)(Î•2-C2H4)2]2 and free diimine. Thus, it was concluded that diimine ligands are not likely coordinated to the active Rh catalysts under catalytic conditions. At 150 °C under catalytic conditions using commercial Cu(OAc)2 as the oxidant, [Rh(μ-OAc)(Î•2-C2H4)2]2 undergoes rapid decomposition to form catalytically inactive and insoluble Rh species, followed by gradual dissolution of the insoluble Rh to form the soluble Rh, which is active for styrene production. Thus, the observed induction period under some conditions is likely due to the formation of insoluble Rh (rapid), followed by redissolution of the Rh (slow). The Rh decomposition process can be suppressed and the catalytically active Rh species maintained by using soluble Cu(II) oxidants or Cu(OAc)2 that has been preheated. In such cases, an induction period is not observed.

KW - arene alkenylation

KW - CH activation

KW - diimine ligand

KW - induction period

KW - rhodium

KW - styrene

UR - https://www.scopus.com/pages/publications/85071174680

U2 - 10.1021/acscatal.9b01480

DO - 10.1021/acscatal.9b01480

M3 - Article

AN - SCOPUS:85071174680

SN - 2155-5435

VL - 9

SP - 7457

EP - 7475

JO - ACS Catalysis

JF - ACS Catalysis

IS - 8

ER -

Mechanistic Studies of Single-Step Styrene Production Catalyzed by Rh Complexes with Diimine Ligands: An Evaluation of the Role of Ligands and Induction Period

Abstract

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