Copper(I) Halides (X = Br, I) Coordinated to Bis(arylthio)methane Ligands: Aryl Substitution and Halide Effects on the Dimensionality, Cluster Size, and Luminescence Properties of the Coordination Polymers

Bis­(phenylthio)­methane (<b>L1</b>) reacts with CuI to yield the 1D-coordination polymer [{Cu₄(μ₃-I)₄}­(μ-<b>L1</b>)₂]_<i>n</i> (<b>1</b>) bearing cubane Cu₄I₄ clusters as connecting nodes. The crystal structures at 115, 155, 195, and 235 K provided evidence for a phase transition changing from the monoclinic space group <i>C</i>2/<i>c</i> to <i>P</i>2₁/<i>c</i>. The self-assembly process of CuI with bis­(<i>p</i>-tolylthio)­methane (<b>L2</b>), bis­(4-methoxyphenylthio)­methane (<b>L3</b>), and bis­(4-bromo-phenylthio)­methane (<b>L4</b>) affords the 1D-coordination polymers [{Cu₄(μ₃-I)₄}­(μ-<b>L<i>x</i></b>)₂]_<i>n</i> (<i>x</i> = 2, 3, or 4). Compounds <b>2</b> and <b>4</b> are isostructural with <i>C</i>2/<i>c</i> low temperature polymorph of <b>1</b>, whereas the inversion centers and 2-fold axes are lost in <b>3</b> (space group <i>Cc</i>). The use of bis­(<i>m</i>-tolylthio)­methane (<b>L5</b>) has no impact on the composition and overall topology of the resulting 1D ribbon of [{Cu₄(μ₃-I)₄}­(μ-<b>L5</b>)₂]_<i>n</i> (<b>5</b>). Even the coordination of the sterically crowded dithioether bis­(5-<i>tert</i>-butyl-2-methylphenylthio)­methane (<b>L8</b>) does not alter the network topology generating the 1D polymer [{Cu₄(μ₃-I)₄}­(μ-<b>L8</b>)₂]_<i>n</i> (<b>8</b>). The 1D polymer [{Cu­(μ₂-Br)₂Cu}­(<b>L1</b>)₂] (<b>9</b>) results from the coordination of <b>L1</b> with CuBr in a 1:1 metal-to-ligand ratio. In contrast to the mean Cu···Cu distances, which are <2.8 Å noted for the Cu₄(μ₃-I)₄ clusters in the 1D polymers <b>1</b>–<b>8</b>, the Cu···Cu contact within the Cu­(μ₂-Br)₂Cu rhomboids of <b>9</b> [2.9194(8) Å] is above the sum of the van der Waals radii of two Cu atoms. The structural arrangement of 1D polymer [{Cu­(μ₂-Br)₂Cu}­(<b>L3</b>)₂]_<i>n</i> (<b>11</b>) is quite similar to that of <b>9</b>. While the reaction of CuBr with <b>L5</b> results in a similar 1D polymer [{Cu­(μ₂-Br)₂Cu}­(<b>L5</b>)₂]_<i>n</i> (<b>12</b>), the reaction of CuBr with <b>L2</b> leads to the dinuclear complex [{Cu­(μ₂-Br)₂Cu}­(η¹-<b>L2</b>)₄] (<b>10</b>) ligated by four pendent bis­(<i>p</i>-tolylthio)­methane ligands. The ligation of bis­(<i>o</i>-tolylthio)­methane, <b>L6</b>, on CuBr also yields a discrete complex [{Cu­(μ₂-Br)₂Cu}­(MeCN)₂(η¹-<b>L6</b>)₂] (<b>13</b>) bearing MeCN and dangling dithioether ligands. A strong luminescence is detected for all CuI polymers, all exhibiting emission lifetimes in the microsecond time scale (i.e., phosphorescence). The polymers containing the Cu₄I₄ core (<b>1</b>–<b>8</b>) exhibit the typically observed low-energy band and sometimes a weaker high-energy band. The nature of the low-energy band was proposed based on literature DFT and TDDFT computations and is predicted to be a mixture of cluster-centered (CC*) and metal/halide-to-ligand charger transfer (M/XLCT). An approximate relationship between the Cu···Cu distance and the emission maxima corroborates the CC* contribution to the nature of the excited states. The emission of the rhomboid-containing materials is assigned to M/XLCT based on literature works on similar motifs