Bazyakina Natalia L, Makarov Valentin M, Ketkov Sergey Yu, Bogomyakov Artem S, Rumyantcev Roman V, Ovcharenko Victor I, Fedushkin Igor L
G.A. Razuvaev Institute of Organometallic Chemistry, Russian Academy of Sciences, Tropinina 49, Nizhny Novgorod 603137, Russian Federation.
International Tomography Center, Siberian Branch of the Russian Academy of Sciences, Institutskaya 3a, Novosibirsk, 630090 Russian Federation.
Inorg Chem. 2021 Mar 1;60(5):3238-3248. doi: 10.1021/acs.inorgchem.0c03647. Epub 2021 Feb 15.
The reactions of monomeric [(dpp-Bian)M(thf)] (M = Ca (), Sr (); dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with 4,4'-bipyridyl (4,4'-bipy) proceed with electron transfer from dpp-Bian to 4,4'-bipy to afford calcium and strontium complexes containing simultaneously radical-anionic dpp-Bian and 4,4'-bipy ligands. In tetrahydrofuran (thf) the reactions result in 1D coordination polymers [{(dpp-Bian)M(4,4'-bipy)(thf)}·4thf] (M = Ca (), Sr ()), while in a thf/benzene mixture the reaction between and 4,4'-bipy affords the 2D metal-organic framework [{(dpp-Bian)Ca(4,4'-bipy)}·2thf·2CH] (). The structures of compounds , and have been determined by single-crystal X-ray analyses. The presence of the ligand-localized unpaired electrons allows the use of ESR spectroscopy for characterization of the compounds , and . DFT calculations of model calcium complexes with the dpp-Bian, 4,4'-bipy, and thf ligands confirm the energetically favorable open-shell configurations of the molecules bearing the 4,4'-bipy fragments. The magnetic susceptibility measurements confirm the presence of two unpaired electrons per monomeric unit in , and . The thermal stability of compounds , and was studied by thermogravimetric analysis (TGA). To the best of our knowledge, is the first MOF simultaneously containing two different paramagnetic bridging ligands inside the framework.
