TY - JOUR
T1 - Understanding the Olefin Polymerization Initiation Mechanism by Cr(III)/SiO2 Using the Activation Strain Model
AU - Núñez-Zarur, Francisco
AU - Comas-Vives, Aleix
N1 - Funding Information:
F.N.Z. wishes to thank Universidad de Medellín for continuous support. A.C.-V. acknowledges the Spanish MEC and the European Social Fund (grant no. RyC-2016-19930) and Spanish Ministerio de Innovación y Universidades (grant no. PGC2018-100818-A-I00). The authors thank Prof. C. Copéret for his guidance on this topic over the past few years.
Funding Information:
F.N.Z. wishes to thank Universidad de Medelli?n for continuous support. A.C.-V. acknowledges the Spanish MEC and the European Social Fund (grant no. RyC-2016-19930) and Spanish Ministerio de Innovacio?n y Universidades (grant no. PGC2018-100818-A-I00). The authors thank Prof. C. Cope?ret for his guidance on this topic over the past few years.
Publisher Copyright:
© 2021 American Chemical Society
PY - 2022/1/13
Y1 - 2022/1/13
N2 - In this work, we computationally analyze the effect of the strain at the Cr(III) sites of a Cr(III)/SiO2 catalyst in the ethylene polymerization initiation considering two possible pathways: ethylene C–H activation and ethylene insertion into the Cr–O bond. We use the activation strain model (ASM), which dissects the activation energy of a reaction into strain and interaction energies, on a series of Cr(III) clusters with different sizes of the Si–O–Si rings. Our results indicate that more strained Cr(III) sites are more active than less strained ones and that the ethylene insertion into the Cr–O bond is more favorable than C–H bond activation for all sites. The ASM analysis reveals that the activation energies of both initiation mechanisms are dually controlled by interaction and strain energies. However, the comparison of the two mechanisms indicates that the preference for the ethylene insertion pathway is due to lower distortion of the ethylene fragment at the transition states, which is ultimately controlled by one intermolecular and one intramolecular interaction between the activated ethylene and the Cr(III) site fragments.
AB - In this work, we computationally analyze the effect of the strain at the Cr(III) sites of a Cr(III)/SiO2 catalyst in the ethylene polymerization initiation considering two possible pathways: ethylene C–H activation and ethylene insertion into the Cr–O bond. We use the activation strain model (ASM), which dissects the activation energy of a reaction into strain and interaction energies, on a series of Cr(III) clusters with different sizes of the Si–O–Si rings. Our results indicate that more strained Cr(III) sites are more active than less strained ones and that the ethylene insertion into the Cr–O bond is more favorable than C–H bond activation for all sites. The ASM analysis reveals that the activation energies of both initiation mechanisms are dually controlled by interaction and strain energies. However, the comparison of the two mechanisms indicates that the preference for the ethylene insertion pathway is due to lower distortion of the ethylene fragment at the transition states, which is ultimately controlled by one intermolecular and one intramolecular interaction between the activated ethylene and the Cr(III) site fragments.
UR - http://www.scopus.com/inward/record.url?scp=85122680473&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.1c09753
DO - 10.1021/acs.jpcc.1c09753
M3 - Artículo
AN - SCOPUS:85122680473
SN - 1932-7447
VL - 126
SP - 296
EP - 308
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
IS - 1
ER -