Reactions of permethyltitanocene tucked-in derivatives with carbon dioxide

0558704 - ÚFCH JH 2023 RIV GB eng J - Journal Article
Pinkas, Jiří - Gyepes, Robert - Polášek, Miroslav - Mach, Karel - Horáček, Michal
Reactions of permethyltitanocene tucked-in derivatives with carbon dioxide.
Dalton Transactions. Roč. 51, č. 26 (2022), s. 10198-10215. ISSN 1477-9226. E-ISSN 1477-9234
R&D Projects: GA ČR(CZ) GA21-01308S
Institutional support: RVO:61388955
Keywords : carbon dioxide * permethyltitanocene
OECD category: Physical chemistry
Impact factor: 4, year: 2022
Method of publishing: Limited access

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.

Permanent Link: http://hdl.handle.net/11104/0332268