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

Bis(phenylthio)methane (<bold>L1</bold>) reacts with CuI to yield the 1D-coordination polymer [{Cu-4(mu 3-I)(4)}(mu-<bold>L1</bold>)(2)]n (<bold>1</bold>) 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 C2/c to P2(1)/c. The self-assembly process of CuI with bis(p-tolylthio)methane (<bold>L2</bold>), bis(4-methoxyphenylthio)methane (<bold>L3</bold>), and bis(4-bromo-phenylthio)methane (<bold>L4</bold>) affords the 1D-coordination polymers [{Cu-4(mu(3)-I)(4)}(mu-<bold>Lx</bold>)(2)]n (x = 2, 3, or 4). Compounds <bold>2</bold> and <bold>4</bold> are isostructural with C2/c low temperature polymorph of <bold>1</bold>, whereas the inversion centers and 2-fold axes are lost in <bold>3</bold> (space group Cc). The use of bis(m-tolylthio)methane (<bold>L5</bold>) has no impact on the composition and overall topology of the resulting 1D ribbon of [{Cu-4(mu(3)-I)(4)}(mu-<bold>L5</bold>)(2)]n (<bold>5</bold>). Even the coordination of the sterically crowded dithioether bis(5-tert-butyl-2-methylphenylthio)methane (<bold>L8</bold>) does not alter the network topology generating the 1D polymer [{Cu4(mu 3-I)4}(mu-<bold>L8</bold>)2]n (<bold>8</bold>). The 1D polymer [{Cu(mu(2)-Br)(2)Cu}(<bold>L1</bold>)(2)] (<bold>9</bold>) results from the coordination of <bold>L1</bold> with CuBr in a 1:1 metal-to-ligand ratio. In contrast to the mean Cu...Cu distances, which are <2.8 angstrom noted for the Cu-4(mu(3)-I)(4) clusters in the 1D polymers <bold>18</bold>, the Cu...Cu contact within the Cu(mu 2-Br)2Cu rhomboids of <bold>9</bold> [2.9194(8) angstrom] is above the sum of the van der Waals radii of two Cu atoms. The structural arrangement of 1D polymer [{Cu(mu(2)-Br)(2)Cu}(<bold>L3</bold>)(2)]n (<bold>11</bold>) is quite similar to that of <bold>9</bold>. While the reaction of CuBr with <bold>L5</bold> results in a similar 1D polymer [{Cu(mu(2)-Br)(2)Cu}(<bold>L5</bold>)(2)]n (<bold>12</bold>), the reaction of CuBr with <bold>L2</bold> leads to the dinuclear complex [{Cu(mu(2)-Br)(2)Cu}(mu 1-<bold>L2</bold>)(4)] (<bold>10</bold>) ligated by four pendent bis(p-tolylthio)methane ligands. The ligation of bis(o-tolylthio)methane, <bold>L6</bold>, on CuBr also yields a discrete complex [{Cu(mu(2)-Br)(2)Cu}(MeCN)(2)(mu 1-<bold>L6</bold>)(2)] (<bold>13</bold>) 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 (<bold>18</bold>) 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.