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2. A New Structural Motif in Aggregation of Methylalumoxanes: Non‐Hydrolytic Route by the Alkylation of Dicarboxylic Acids.

Author

Pietrzykowski, Antoni, Justyniak, Iwona, Szejko, Vadim, Skrok, Tomasz, Radzymiński, Tomasz, Suwińska, Kinga, and Lewiński, Janusz

Subjects
DICARBOXYLIC acids, SUCCINIC acid, MOLECULAR structure, ITACONIC acid, ALUMINUM compounds
Abstract

Alumoxanes are typically produced via controlled hydrolysis of short‐chain alkyl aluminium compounds which leads to oligomeric species that are usually difficult to obtain in crystalline form. Simultaneously, various alternative non‐hydrolytic approaches to alumoxanes have also been used. In this work, we report on a new methylalumoxane scaffold derived from the alkylation of a series of dicarboxylic acids: itaconic acid (HO2CCH2C(=CH2)CO2H), succinic acid (HO2CCH2CH2CO2H) and homophthalic acid (HO2CCH2C6H4CO2H). The reactions of AlMe3 with a selected dicarboxylic acid in the molar ratio 4 : 1 conducted at elevated temperature occur with double methylation of each carboxylic group and provide to the formation of a new methylalumoxane aggregate, Me10Al6O4, flanked by methylaluminium diolate units. We also aimed to obtain dialkylaluminium derivatives of dicarboxylic acids by the controlled reaction of the appropriate acid with AlMe3 in the 1 : 2 stoichiometry. While the synthesis of organoaluminium derivatives of flexible aliphatic dicarboxylic acids (itaconic and succinic acids) is challenging due to their insolubility, the related homophtalate compound readily forms a molecular tetranuclear cluster, [([(O2CCH2C6H4CO2)(μ‐AlMe2)2]2. The molecular and crystal structures of the resulting compounds were determined via NMR spectroscopic analysis and single crystal X‐ray diffraction crystallography. [ABSTRACT FROM AUTHOR]

Published
2024
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9. The influence of structural isomerism on luminescence properties of [Re(CO)2(dppv)(pbi)] complexes containing cis-1,2-bis(diphenylphosphino)-ethene and 2-(2-pyridyl)benzimidazole ligands.

Author

Kamecka, Anna, Kapturkiewicz, Andrzej, Shova, Sergiu, and Suwińska, Kinga

Subjects
STRUCTURAL isomerism, LIGANDS (Chemistry), LUMINESCENCE, LUMINOPHORES, EXCITED states, ISOMERS
Abstract

Simple reaction procedure, boiling of an equimolar mixture of [Re(Cl)(CO)3(dppv)] (dppv—cis-1,2-bis(diphenylphosphino)-ethene), 2-(2-pyridyl)benzimidazole (pbi), and TlClO4 in o-dichlorobenzene solution, leads to two, chromatographically separable, isomers of [Re(CO)2(dppv)(pbi)] complex. The obtained species, the yellow-emissive [OC-6–54] and the orange-emissive [OC-6–53] isomers, have been identified using FT-IR, 1H NMR, and 31P NMR spectroscopy and their structures confirmed by means of X-ray investigations. According to obtained crystallography results, the investigated isomers differ mainly in the arrangement of the 2-(2-pyridyl)benzimidazole anion in their structures. Diverse arrangement of the dppv and pbi ligand around the central cis-[Re(CO)2]+ core results in well-pronounced changes in luminescence properties of the studied luminophores. According to results from performed DFT and TDA-DFT computations, the [OC-6–54] isomer emission occurs from the intra-ligand excitation localized mainly within the pbi ligand. In contrary to that, the [OC-6–53] isomer emission indicates some metal-to-ligand charge-transfer character associated with the charge transfer from the Re(CO)2(dppv)+ fragment to the pbi ligand. Moreover, both isomers exhibit different character of their emission decays, mono-exponential and bi-exponential for the [OC-6–54] and [OC-6–53] ones, respectively. In the view of obtained DFT/TDA-DFT results, this has been explained by the presence of an additional excited dark state, operative only in the case of the [OC-6–53] isomer and associated with the charge transfer from the Re(CO)2(pbi) fragment to the dppv ligand. [ABSTRACT FROM AUTHOR]

Published
2023
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