Uranyl ion coordination by benzene‐1,2,3‐tricarboxylate: building chains and networks from binuclear bricks
Résumé
Benzene-1,2,3-tricarboxylic acid (123btcH$_3$) was used to synthesize 7 uranyl ion complexes under hydrosolvothermal conditions, in the presence of different structure-directing agents. [Zn(phen)$_3$][Zn$_2$(123btc)(phen)$_4$][(UO$_2$)2(123btc)$_2$(OH)(CH$_3$CN)]$^\cdot$3H$_2$O (1, phen = 1,10-phenanthroline), the only discrete species in the series, crystallizes as a binuclear, cup-shaped dimer. Both [PP$_3$Me][UO$_2$(123btc)] (2) and [C(NH$_2$)$_3$][UO$_2$(123btc)]$^\cdot$0.5H$_2$O (3) contain anionic, monoperiodic coordination polymers based on quasi-planar, binuclear (UO$_2$)$_2$(123btc)$_2$$^{2-}$subunits in which two oxygen atoms of each ligand are uncoordinated. Similar chains are found in [UO$_2$(123btc)K(18C6)]$^\cdot$H$_2$O (4, 18C6 = 18-crown-6), the potassium cations being decorating groups bound to carboxylato and uranyl oxo donors. An analogous decorating role to monoperiodic polymers is played by UO$_2$(DMF)$_2$(H$_2$O)$_2$$^{2+}$ cations in [(UO$_2$)$_3$(123btc)$_2$(DMF)$_2$(H$_2$O)$_2$] (5), while bridging of chains by UO$_2$(NMP)$_3$$^{2+}$ cations in [(UO$-2$)$-3$(123btc)$-2$(NMP)$-3$] (6) yields a diperiodic network with V$_2$O$_5$ topology. [NH$_4$][UO$_2$(123btc)] (7), which does not contain the dimeric subunit found in the other cases, crystallizes as a diperiodic network with sql topology, the layers being associated through hydrogen bonding interactions with the ammonium counterions.
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