Framework robustness in early d-block metal complexes with tripodal polyalcohol ligands

Carla Krupczak, Bruno J. Stoeberl, Kátia C. M. Westrup, Lorenzo Tesi, Francielli S. Santana, Siddhartha O. K. Giese, Fabiano Yokaichiya, Daniel da S. Costa, Juliana M. Missina, Danilo Stinghen, David L. Hughes, Roberta Sessoli, Giovana G. Nunes, Dayane M. Reis, Jaísa F. Soares

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While performing our research on the tetranuclear "star-shaped" complexes formulated as [M3M'(LR)2(dpm)6], where M, M' are first-row d-block metals; H3LR is a tripodal alcohol, RC(CH2OH)3, with R = Et, Me or Ph; and Hdpm = dipivaloylmethane, we isolated a series of binuclear, alkoxide-bridged chelate complexes of titanium and chromium upon spontaneous deprotonation of the polyalcohol. In the titanium system, both [TiIII2Cl4(H2LEt)2]·4thf and [TiIV2Cl4(HLEt)2]·2thf were identified; they present analogous binuclear frameworks but distinct metal oxidation states and polyalcohol deprotonation degrees. Four similar CrIII2 compounds were also isolated, differing in the tripodal R groups and cocrystallized solvent or proligand molecules. The products were characterized by single-crystal X-ray diffraction analysis and spectroscopic, thermogravimetric and magnetic measurements. Cocrystallization influences the nature, strength and pattern of intermolecular interactions. Among the binuclear MIII products, all those containing solvating tetrahydrofuran, [M2Cl4(H2LR)2]·x thf (R = Et, Ph; x = 4 or 5 respectively), lose solvent upon gradual polyalcohol deprotonation, mild heating or vacuum drying. The versatile tripodal skeleton assembles the alkoxide-bridged M2 units (M = TiIII/IV or CrIII) in various experimental conditions, including air or inert atmosphere and non-protic or protic media, and confers remarkable robustness to the final binuclear aggregates.
Original languageEnglish
Article number134360
JournalJournal of Molecular Structure
Issue numberPart 1
Early online date17 Oct 2022
Publication statusPublished - 15 Feb 2023

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