Issue 46, 2020

Structure and dynamics of catalytically competent but labile paramagnetic metal-hydrides: the Ti(iii)-H in homogeneous olefin polymerization

Abstract

Metal hydride complexes find widespread application in catalysis and their properties are often understood on the basis of the available crystal structures. However, some catalytically relevant metal hydrides are only spontaneously formed in situ, cannot be isolated in large quantities or crystallised and their structure is therefore ill defined. One such example is the paramagnetic Ti(III)-hydride involved in homogeneous Ziegler–Natta catalysis, formed upon activation of CpTi(IV)Cl3 with modified methylalumoxane (MMAO). In this contribution, through a combined use of electron paramagnetic resonance (EPR), electron-nuclear double resonance (ENDOR) and hyperfine sublevel correlation (HYSCORE) spectroscopies we identify the nature of the ligands, their bonding interaction and the extent of the spin distribution. From the data, an atomistic and electronic model is proposed, which supports the presence of a self-assembled ion pair between a cationic terminal Ti-hydride and an aluminate anion, with a hydrodynamic radius of ca. 16 Å.

Graphical abstract: Structure and dynamics of catalytically competent but labile paramagnetic metal-hydrides: the Ti(iii)-H in homogeneous olefin polymerization

Supplementary files

Article information

Article type
Edge Article
Submitted
08 sep 2020
Accepted
24 sep 2020
First published
24 sep 2020
This article is Open Access

All publication charges for this article have been paid for by the Royal Society of Chemistry
Creative Commons BY license

Chem. Sci., 2020,11, 12436-12445

Structure and dynamics of catalytically competent but labile paramagnetic metal-hydrides: the Ti(III)-H in homogeneous olefin polymerization

E. Salvadori, M. Chiesa, A. Buonerba and A. Grassi, Chem. Sci., 2020, 11, 12436 DOI: 10.1039/D0SC04967K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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