Increasing Structure Dimensionality of Copper(I) Complexes by Varying the Flexible Thioether Ligand Geometry and Counteranions

This work focuses on the systematic investigation of the influences of pyrimidine-based thioether ligand geometries and counteranions on the overall molecular architectures. A N-containing heterocyclic dithioether ligand 2,6-bis(2-pyrimidinesulfanylmethyl)pyridine (<b>L1</b>) and three structurally related isomeric bis(2-pyrimidinesulfanylmethyl)benzene (<b>L2</b>−<b>L4</b>) ligands have been prepared. On the basis of the self-assembly of CuX (X = I, Br, Cl, SCN, or CN) and the four structurally related flexible dithioether ligands, we have synthesized and characterized 10 new metal−organic entities, Cu₄(<b>L1</b>)₂I₄ <b>1</b>, Cu₄(<b>L1</b>)₂Br₄ <b>2</b>, [Cu₂(<b>L2</b>)₂I₂·CH₃CN]<i>_n</i> <b>3</b>, [Cu(<b>L3</b>)I]<i>_n</i> <b>4</b>, [Cu(<b>L3</b>)Br]<i>_n</i> <b>5</b>, [Cu(<b>L3</b>)CN]<i>_n</i> <b>6</b>, [Cu(<b>L4</b>)CN]<i>_n</i> <b>7</b>, [Cu₂(<b>L4</b>)I₂]<i>_n</i> <b>8</b>, [Cu₂(<b>L4</b>)(SCN)₂]<i>_n</i> <b>9</b>, and {[Cu₆I₅(<b>L4</b>)₃](BF₄)·H₂O}<i>_n</i> <b>10</b>, by elemental analyses, IR spectroscopy, and X-ray crystallography. Single-crystal X-ray analyses show that the 10 Cu(I) complexes possess an increasing dimensionality from 0D (<b>1</b> and <b>2</b>) to 1D (<b>3</b>−<b>5</b>) to 2D (<b>6</b>−<b>9</b>) to 3D (<b>10</b>), which indicates that the ligand geometry takes an essential role in the framework formation of the Cu(I) complexes. The influence of counteranions and π−π weak interactions on the formation and dimensionality of these coordination polymers has also been explored. In addition, the photoluminescence properties of Cu(I) coordination polymers <b>4</b>−<b>10</b> in the solid state have been studied.