Substituent Effects and Supramolecular Interactions of Titanocene(III) Chloride: Implications for Catalysis in Single Electron Steps

TitleSubstituent Effects and Supramolecular Interactions of Titanocene(III) Chloride: Implications for Catalysis in Single Electron Steps
Publication TypeJournal Article
Year of Publication2014
AuthorsGansauer A, Flowers, II RA, Sadasivam D, Kube C, Daasbjerg K, Sure R, Grimme S, Fianu G
JournalJournal of the American Chemical Society
Volume136
Issue4
Start Page1663
Pagination1671
Date Published01/2014
Abstract

The electrochem. properties of titanocene(III) complexes and their stability in THF in the presence and absence of chloride additives were studied by cyclic voltammetry (CV) and computational methods. The anodic peak potentials of the titanocenes can be decreased by as much as 0.47 V through the addn. of an electron-​withdrawing substituent (CO2Me or CN) to the cyclopentadienyl ring when compared with Cp2TiCl. For the 1st time, under the conditions of catalytic applications low-​valent titanocenes can decomp. by loss of the substituted ligand. The recently discovered effect of stabilizing titanocene(III) catalysts by chloride additives was analyzed by CV, kinetic, and computational studies. An unprecedented supramol. interaction between [(C5H4R)​2TiCl2]​-​ and hydrochloride cations through reversible H bonding is proposed as a mechanism for the action of the additives. This study provides the crit. information required for the rational design of titanocene-​catalyzed reactions in single electron steps.