Anion-templating self-assembly of [Cu2(OMe)2]2+ SBUs depending on the size of the anion in the solid state

Abstract The solution reaction of btp [2,6-bis( N 1-1,2,4-triazolyl)pyridine] with copper acetate afforded a secondary building unit (SBU) precursor of [Cu 2 (OAc) 4 (btp) 2 ] · 2MeOH ( 1 ) which yielded the [Cu 2 (OMe) 2 ] 2+ SBU by the reaction of 1 with CuX 2 salts (X = [BF 4 ] − , [ClO 4 ] − and [OTf] − ) in methanol and acetonitrile mixture. According to solid-state structural analysis, self-assembly of SBUs is dependent on the size of the anion. In the case of [BF 4 ] − and [ClO 4 ] − , SBUs are self-assembled to be 3D cages of [[[Cu 4 (μ-OMe) 4 (μ-btp) 4 (BF 4 ) 2 (MeCN) 2 ] ⊃ (BF 4 )](BF 4 )][[[Cu 4 (μ-OMe) 4 (μ-btp) 4 (BF 4 )(MeOH)(MeCN) 2 ] ⊃ (BF 4 )](BF 4 ) 2 ] ( 2 ) and [[Cu 4 (μ-OMe) 4 (μ-btp) 4 (ClO 4 ) 2 (MeCN) 2 ] ⊃ (ClO 4 )](ClO 4 ) · 2H 2 O ( 3 ) by the anion-templating effect, where two SBUs are bridged by four btp ligands. The bending of Cu 2 O planes along the O⋯O hinge causes the btp ligands to get close enough to interconnect two [Cu 2 (OMe) 2 ] 2+ SBUs in addition to the orthogonal arrangement of Cu⋯Cu axes of each SBU. Meanwhile, the large anion [OTf] − was not capable of the 3D cage but a 1D infinite coordination polymer of [[Cu 2 (μ-OMe) 2 (μ-OTf) 2 (btp) 2 ](H 2 O)] n ( 4 ) in which SBUs are doubly bridged by btp ligands in a zigzag pattern.