Uranyl Ion Coordination by Benzene‐1,2,3‐tricarboxylate: Building Chains and Networks from Binuclear Bricks

Abstract

Benzene-1,2,3-tricarboxylic acid (123btcH3) was used to synthesize 7 uranyl ion complexes under hydrosolvothermal conditions, in the presence of different structure-directing agents.[Zn(phen1, phen = 1,10-phenanthroline), the only discrete species in the series, crystallizes as a binuclear, cup-shaped dimer. Both [PPh3Me][UO2(123btc)] (2) and [C(NH2)3][UO2(123btc)]0.5H2O (3) contain anionic, monoperiodic coordination polymers based on quasi-planar, binuclear (UO2)2(123btc)2 2subunits in which two oxygen atoms of each ligand are uncoordinated. Similar chains are found in [UO2(123btc)K(18C6)]H2O (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 UO2(DMF)2(H2O)2 2+ cations in [(UO2)3(123btc)2(DMF)2(H2O)2] (5), while bridging of chains by UO2(NMP)3 2+ cations in [(UO2)3(123btc)2(NMP)3] (6) yields a diperiodic network with V2O5 topology.[NH4][UO2(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.

Ni(2,2′:6′,2″-Terpyridine-4′-carboxylate)2 Zwitterions and Carboxylate Polyanions in Mixed-Ligand Uranyl Ion Complexes with a Wide Range of Topologies

“…Separation of charges is also found with citH 3– , but here semi-interpenetration of monoperiodic, anionic uranyl citrate chains into a diperiodic, cationic sql network incorporating uranyl and Ni­(tpyc) 2 is observed. The formation of rather similar uranyl-based monoperiodic polymers with 1,2,3-btc 3– and citH 3– is in keeping with the previously noted relatedness of these two ligands in their uranyl ion complexes . More usual hcb diperiodic networks are found with btcH 3– and cbtcH 3– , in which these ligands are 3-c nodes only due to the carboxylic group being uncoordinated, which prevents formation of a triperiodic framework.…”

“…The formation of rather similar uranylbased monoperiodic polymers with 1,2,3-btc 3− and citH 3− is in keeping with the previously noted relatedness of these two ligands in their uranyl ion complexes. 73 More usual hcb diperiodic networks are found with btcH 3− and cbtcH 3− , in which these ligands are 3-c nodes only due to the carboxylic group being uncoordinated, which prevents formation of a triperiodic framework. Other diperiodic networks, with the sql or KIa topologies, are formed with the dicarboxylates ndc 2− and 1,3-pda 2− acting as simple links.…”

“…The formation of rather similar uranyl-based monoperiodic polymers with 1,2,3-btc 3and citH 3is in keeping with the previously noted relatedness of these two ligands in their uranyl ion complexes. 73 More usual hcb diperiodic networks are found with btcH 3and cbtcH 3- In all but two instances (complexes 13 and 14), a degree of association or interlocking of Ni(tpyc)2 units is apparent which resembles that described as the "terpyridine embrace" although here it does not extend beyond pairwise or extended linear arrays. In complex 13, stacking does occur but it associates tpycand 1,3-pda 2units, whereas in complex 14 the uranyl oxo interaction with tpycblocks the approach of other tpycunits.…”

“…results in TE interactions between chains adjacent along [010] (NiNi distance, 8.3154(8) Å), with one parallel-displaced -stacking interaction [centroidcentroid distance, 3.611(3) Å; dihedral angle, 8.4(3)°] and one CH interaction [Hcentroid distance, 2.63 Å; C-Hcentroid angle, 149°].With the quite rigid 1,2,3-benzenetricarboxylate (1,2,3-btc 3-) ligand, a rather dramatic change in the nature of the product occurs, the complex [Ni(tpycH)(H2O)3][UO2(1,2,3btc)]22H2O (7) (Figure8) having an ionic composition. The two independent uranyl ions are in similar environments, each being chelated by two carboxylate groups from two 1,2,3-btc3- ligands forming two seven-membered rings and bound to a fifth carboxylate oxygen donor from a third ligand, thus giving a monoperiodic coordination polymer parallel to [10ī] of a form essentially identical to that known in association with various counterions or decorating cations 73. This indication of a particular stability of the polymer may explain its resistance to incorporation of Ni(tpyc)2 and its crystallization in association with a cation of dipositive charge involving the undeprotonated form of tpycH.…”