Control of Copper(I) Iodide Architectures by Ligand Design: Angular versus Linear Bridging Ligands

A family of coordination polymers formed by the reaction of copper(I) iodide with a range of angular bidentate or tridentate N-donor ligands is reported. The framework polymers [CuI(dpt)]∞ 1 [dpt = 2,4-bis(4-pyridyl)-1,3,5-triazine], [CuI(dpb)]∞ 2 [dpb = 1,4-bis-(4-pyridyl)-benzene], [(CuI)3(dpypy)2]∞ 3, [CuI(dpypy)]∞ 4 [dpypy = 3,5-bis(4-pyridyl)-pyridine], and [Cu3I3(pypm)]∞ 5 [pypm = 5-(4-pyridyl)pyrimidine] have been prepared and structurally characterized. It was found that the angular nature of the dpypy and dpt ligands favors the formation of discrete (CuI)2 dimeric subunits as observed in [CuI(dpt)·MeCN]∞ 1 and [(CuI)3(dpypy)2]∞ 3. In contrast, reaction with the linear ligand dpb affords [CuI(dpb)]∞ 2 which incorporates a one-dimensional (CuI)∞ chain structure. Moreover, the additional donor available on the central ring of the dpypy ligand generates a novel two-dimensional bilayer structure in 3, in contrast to the one-dimensional ribbon structure observed in the case of 1. Interestingly, the bilayer structure of 3 additionally exhibits 2-fold interpenetration. The reaction of CuI with dpypy produces not only 3 but a further product [CuI(dpypy)]∞ 4 that has been characterized as a one-dimensional chain constructed from trigonal-planar Cu(I) centers bridged by bidentate dpypy ligands. Compound 5, [Cu3I3(pypm)]∞, exhibits a highly unusual three-dimensional structure in which the pypm ligand bridges two-dimensional brick-wall (CuI)∞ sheets.