Li₂ADC·2H₂O and Li₂ADC: Two new Coordination Polymers with the Acetylenedicarboxylate Dianion (ADC^2–)

Abstract

Single crystals of dilithium‐acetylenedicarboxylate‐dihydrate, Li2ADC·2H2O (1), were isolated from a solid product formed by isothermal evaporation of an aqueous solution of LiOH und acetylenedicarboxylic acid (H2ADC). 1 crystallizes in the triclinic space group P1 with Z = 2. LiO4 tetrahedra are interconnected by ADC2– anions and water molecules to form a 3D polymeric structure. Coupled TGA and DTA measurements show that 1 loses its two water molecules above 100 °C. Heating a polycrystalline sample of 1 at 140 °C for 2 h in an argon atmosphere leads to a significant change of the powder diffraction pattern indicating the formation of the new anhydrous coordination polymer dilithium‐acetylenedicarboxylate, Li2ADC (2). Its crystal structure was solved and refined from X‐ray powder diffraction data. 2 crystallizes in the orthorhombic space group Fddd (Z = 8). LiO4 tetrahedra are interconnected by ADC2– anions to form a 3D polymeric structure.

Acetylenedicarboxylate as a linker in the engineering of coordination polymers and metal–organic frameworks: challenges and potential

“…Two water molecules (O3) bridge two Na atoms each, while the third water (O4) molecule exhibits a terminating coordination. One oxygen atom of the carboxylate group of ADC (O22) also bridges three Na atoms, 41 whereas the second oxygen atom of the carboxylate group (O21) is non-coordinating. That is, ADC coordinates in a µ 3 -η 3 :η 0 mode with each of its carboxylate groups (cf.…”

“…3(c) and (d)). 41 Interestingly, heating [Li 2 (ADC)(H 2 O) 2 ] at 140 1C for 2 h yields the new coordination polymer [Li 2 (ADC)] as the first reported anhydrous alkali metal acetylenedicarboxylate. [Li 2 (ADC)] has an entirely different structure compared to [Li 2 (ADC)(H 2 O) 2 ], with the Li atom being in this case coordinated by four oxygen atoms of four carboxylate groups from four different ADC linkers (Fig.…”

“…upon reaction of H 2 ADC with Li(OH) in water (vide supra),41 whereas in situ hydroiodination to [Li(HOOC-CH=CI-COO)(H 2 O)] occurs upon reaction of H 2 ADC with LiI in water 132. This hypothesis is also in line with the formation of [Cu(OOC-CH=CCl-COO)(H 2 O) 2 ]•H 2 O, as H 2 ADC and CuCl 2 as metal salt…”

Eu(O2C‐C≡C‐CO2): An EuII Containing Anhydrous Coordination Polymer with High Stability and Negative Thermal Expansion

“…On the other hand, the field of anhydrous homoleptic CPs with the ADC 2− ligand is extremely small. At the moment only reports on the synthesis and crystal structure of SrADC, PbADC, CaADC, and Li 2 ADC are available. All compounds with composition M II ADC crystallize in the SrADC type structure ( I 4 1 / amd , no.…”

Completing the Series: New Coordination Networks of Composition 3∞[RE2(ADC)3(H2O)6]·2H2O with RE = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Y and ADC2– = Acetylenedicarboxylate (–O2C–C≡C–CO2–)

“…Almost ten years later, it was mainly our group that started to revive this chemistry by adding numerous hydrates, but also anhydrous coordination polymers to this class of compounds . Focusing on the metal nodes we were able to synthesize acetylenedicarboxylates with alkali metals (Li + , Na + , K + [6] ), alkaline earth metals (Mg 2+ , Ca 2+ , Sr 2+ [8] ), main group metals (Tl + , Cd 2+ , Pb 2+ ), and transition metals (Co 2+ , Ni 2+ , Cu 2+ , Zn 2+ [15] ). It is a remarkable structural feature of all these compounds, which exhibit 1D, 2D as well as 3D polymeric fragments, that the ADC 2– ligands are aligned almost parallel to each other.…”