3D Coordination Framework with Uncommon Two‐Fold Interpenetrated {3 3 ⋅5 9 ⋅6 3 }‐lcy Net and Coordinated Anion Exchange

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.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.