Issue 26, 2022

Reactions of permethyltitanocene tucked-in derivatives with carbon dioxide

Abstract

Both single tucked-in permethyltitanocene 1 and double tucked-in permethyltitanocene 2 react with excess CO2 by insertion into their Ti–CH2 bonds. The former one precipitates instantly a yellow carboxylate-tethered oligomer [3]n which is insoluble in aprotic solvents and in a vacuum it sublimes as a monomer without decomposition. Computations for n ≤ 4 optimised the structure of the monomer [3] and showed that open chain oligomers bound by dative O → Ti bonds were not sterically hindered. The latter bond dissociates when [3]n is oxidized by chlorination with CDCl3 or CD2Cl2 to give Ti(IV) chloride 4 or upon metathesis of [3]n with Me3SiCl yielding Ti(III) chloride 5. Oxidative addition of MeCN affords a C–C coupled dinuclear titanocene diimine 6. Compound [3]n also reacts with 1 to give the tethered carbodiolate 8 or with [Cp*2TiH] (where Cp* = η5-C5Me5) to give the half-tethered carbodiolate 10. The non-tethered carbodiolate 12 was obtained from [Cp*2TiH] and CO2 yielding titanocene formate by reaction of the latter with another equivalent of [Cp*2TiH]. All these carbodiolates contain Ti(III) metal atoms forming electronic triplet states of axial or orthorhombic symmetry. In contrast to the rapidly reacting 1 compound 2 reacts with excess CO2 slowly in m-xylene at 100 °C using only one of its two Ti–CH2 moieties. The structure of the obtained carbodiolate 13 indicates that the primary product analogous to 3 reacts with 2 more rapidly than with CO2.

Graphical abstract: Reactions of permethyltitanocene tucked-in derivatives with carbon dioxide

Supplementary files

Article information

Article type
Paper
Submitted
29 Apr 2022
Accepted
08 Jun 2022
First published
10 Jun 2022

Dalton Trans., 2022,51, 10198-10215

Reactions of permethyltitanocene tucked-in derivatives with carbon dioxide

J. Pinkas, R. Gyepes, M. Polášek, K. Mach and M. Horáček, Dalton Trans., 2022, 51, 10198 DOI: 10.1039/D2DT01344D

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