Tautomeric Equilibrium of an Asymmetric β-Diketone in Halogen-Bonded Cocrystals with Perfluorinated Iodobenzenes

Martinez, Valentina; Bedeković, Nikola; Stilinović, Vladimir; Cinčić, Dominik (2021) Tautomeric Equilibrium of an Asymmetric β-Diketone in Halogen-Bonded Cocrystals with Perfluorinated Iodobenzenes. Crystals, 11 (6). pp. 699-713. ISSN 2073-4352

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Official URL: https://www.mdpi.com/2073-4352/11/6/699

Abstract

In order to study the effect of halogen bond on tautomerism in β-diketones in the solid-state, we have prepared a series of cocrystals derived from an asymmetric β-diketone, benzoyl-4-pyridoylmethane (b4pm), as halogen bond acceptor and perfluorinated iodobenzenes: iodopentaflourobenzene (ipfb), 1, 2-, 1, 3- and 1, 4-diiodotetraflorobenzene (12tfib, 13tfib and 14tfib) and 1, 3, 5-triiodo-2, 4, 6-trifluorobenzene (135titfb). All five cocrystals are assembled by I···N halogen bonds involving pyridyl nitrogen and iodoperfluorobenzene iodine resulting in 1:1 (four compounds) or 1:2 (one compound) cocrystal stoichiometry. Tautomer of b4pm in which hydrogen atom is adjacent to the pyridyl fragment was found to be more stable in vacuo than tautomer with a benzoyl hydroxyl group. This tautomer is also found to be dominant in the majority of crystal structures, somewhat more abundantly in crystal structures of cocrystals in which additional I···O halogen bond with the benzoyl oxygen has been established. Attempts have also been made to prepare an equivalent series of cocrystals using a closely related asymmetric β-diketone, benzoyl-3-pyridoylmethane (b3pm) ; however, all attempts were unsuccessful, which is attributed to more effective crystal packing of b3pm isomer compared to b4pm, which reduced the probability of cocrystal formation.

Item Type:

Article

Uncontrolled Keywords:

pyridyl-diketone ; halogen bonding ; intramolecular hydrogen bonding ; tautomerization

Subjects:

NATURAL SCIENCES > Chemistry

Divisions:

Division of Physical Chemistry

Projects:

Project title	Project leader	Project code	Project type
Kristalno inženjerstvo višekomponentinih metaloorganksih materijala povezanih halogenskom vezom: ususret supramolekulskom ugađanju strukture i svojstava	Cinčić, Dominik	IP-2014-09-7367	HRZZ
Nove građevne jedinke u supramolekulskom dizajnu složenih višekomponentnih molekulskih kristala temeljenih na halogenskim vezama	Cinčić, Dominik	IP-2019-04-1868	HRZZ

Depositing User:

Valentina Martinez

Date Deposited:

03 Aug 2021 10:41

URI:

http://fulir.irb.hr/id/eprint/6503

DOI:

10.3390/cryst11060699