An achiral (10,3) net three-dimensional metal-oxalato framework [Cu₂(C₂O₄)₃ ²⁻]_n was formed by cation-templating. At around 165 K, the disorder–order transition of cation (C₂H₅)₃NH⁺ hosted in the channel resulted in dielectric transition, and the antiferromagnetic interactions between the Jahn–Teller distorted Cu(II) through the oxalato-bridge below 165 K was enhanced.

An organic–inorganic hybrid combining a semiconducting BEDT-TTF layer and a Jahn–Teller distorted oxalato-bridged honeycomb antiferromagnetic layer [Cu₂(C₂O₄)₃ ²⁻]_n was obtained and characterized.

As with quantum spin liquids based on two-dimensional triangular and kagome lattices, the two-dimensional honeycomb lattice with either a strong spin-orbital coupling or a frustrating second-nearest-neighbor coupling is expected to be a source of candidate quantum spin liquids. An ammonium salt [(C3H7)3NH]2[Cu2(C2O4)3](H2O)2.2 containing hexagonal layers of Cu2+ was obtained from solution. No structural transition or long-range magnetic ordering was observed from 290 K to 2 K from single crystal X-ray diffraction, specific heat and susceptibility measurements. The anionic layers are separated by sheets of ammonium and H2O with distance of 3.5 Å and no significant interaction between anionic layers. The two-dimensional honeycomb lattice is constructed from Jahn-Teller distorted Cu2+ and oxalate anions, showing a strong antiferromagnetic interaction between S = 1/2 metal atoms with θ = −120 (1) K. Orbital analysis of the Cu2+ interactions through the oxalate-bridges suggests a stripe mode pattern of coupling with weak ferromagnetic interaction along the b axis, and strong antiferromagnetic interaction along the a axis. Analysis of the magnetic susceptibility shows that it is dominated by a quasi-one-dimensional contribution with spin chains that are at least as well isolated as those of well-known quasi-one-dimensional spin liquids.