Abstract
Unusual {3^3^⋅5^9^⋅6^3^}‐lcy topology has been found in an uncommon 3D six‐connected, two‐fold interpenetrated {3^3^⋅5^9^⋅6^3^}‐lcy net (illustrated). The coordinated SO~4~^2−^ anions in this framework can undergo a full exchange with Cl^−^ anions, in the course of which the crystals change color as shown. The process has a solvent‐mediated rather than a solid‐state mechanism.magnified image
Reaction of tetrazole‐1‐acetic acid with CuSO~4~⋅5H~2~O produces two novel 3D coordination frameworks: ([Cu~3~(μ~3~‐OH)(η^1^:η^1^:η^1^:μ~3~‐SO~4~)(tza)~3~]⋅3 CH~3~OH⋅H~2~O}~n~ (1; Htza=tetrazole‐1‐acetic acid) and {[Cu~4~(μ~2~‐OH)(η^2^:η^2^:μ~4~‐SO~4~)(tta)~5~]⋅3 H~2~O}~n~ (2; Htta=tetrazole). Framework 1 is constructed from a trinuclear copper cluster [Cu~3~(μ~3~‐OH)(η^1^:η^1^:η^1^:μ~3~‐SO~4~)] and displays a six‐connected framework with uncommon {3^3^⋅5^9^⋅6^3^}‐lcy topology. Framework 2 presents a complicated five‐nodal (3,4,6)‐connected net with (4^2^⋅6)(3⋅4^2^⋅5^2^⋅7)(4^3^⋅6^2^⋅8)(3^2^⋅4^8^⋅5^3^⋅6^2^)(4^6^⋅8^6^⋅10^3^) topology. The η^2^:η^2^:μ~4~‐SO~4~ bridging mode in 2 has not been found in the reported coordination polymers. The coordinated SO~4~^2−^ anions in 1 can be replaced completely when the solid polymer is treated with an aqueous methanolic solution containing Cl^−^ anions. Detailed atomic force microscopy studies indicate a solvent‐mediated rather than a solid‐state mechanism for the exchange process.