Copper(II) coordination polymers of imdc− (H2imdc+ = the 1,3-bis(carboxymethyl)imidazolium cation): unusual sheet interpenetration and an unexpected single crystal-to-single crystal transformation
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Date
2013-10-08
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Publisher
Royal Society of Chemistry
Abstract
The monoanion of 1,3-bis(carboxymethyl)imidazolium (H2imdc+) combines with Cu(II) to produce an undulating 2D coordination polymer of composition [Cu2(imdc)2(CH3OH)2](BF4)2·(CH3OH)(H2O) (1) in which copper acetate-like dimers, linked by imdc− ligands, act as 4-connecting centres. Cationic sheets stack on top of each other in an A, B, A, B… fashion and produce a structure that contains channels running parallel to the plane of network.
Tetrafluoroborate anions are located in channels between sheets. Upon removal of coordinated and noncoordinated solvent molecules a single crystal-to-single crystal transformation occurs to yield a similar compound but with BF4 − anions now coordinated. CO2 isotherms measured at 258 and 273 K show only modest uptake of
CO2 but provide an indication that the sheets move apart at elevated pressures in order to accommodate the guest molecules. A compound of composition [Cu3(OH)2(imdc)2]·SiF6·2H2O·2MeOH (3), which possesses a 3D network, is formed by the combination of copper(II) acetate, copper(II) hexafluorosilicate and Himdc. In this structure infinite parallel Cu3(OH)2 chains are linked by bridging imdc− ligands to form channels that have an approximately
triangular cross-section. These channels are occupied by SiF6 2− anions in addition to solvent molecules. When copper(II) acetate is combined with Himdc in the appropriate ratio, a 1D coordination polymer of composition Cu(imdc)2 (4) is formed in which pairs of imdc− anions bridge Cu(II) centres. When the reaction is performed in the presence of NaBF4 a minor crystalline product with tetragonal symmetry is isolated in addition to the 1D coordination polymer. This compound of composition Cu2(imdc)4NaBF4·7H2O (5) consists of 2D Cu(imdc)2
networks and features an unusual mode of interpenetration. © 2013, The Royal Society of Chemistry.
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Keywords
Polymers, Copper, Solvents, Molecules, Crystal structure, Ligands
Citation
Abrahams, B. F., Maynard-Casely, H. E., Robson, R., & White, K. F. (2013). Copper(ii) coordination polymers of imdc− (H2imdc+ = the 1,3-bis(carboxymethyl)imidazolium cation): unusual sheet interpenetration and an unexpected single crystal-to-single crystal transformation. CrystEngComm, 15(45), 9729-9737. doi:10.1039/C3CE41226A