Impact of ligand framework on the crystal structures and luminescent properties of Cu(I) and Ag(I) clusters and a coordination polymer derived from thiolate/iodide/dppm ligands.

Abstract

New homoleptic hexanuclear Ag(I) and heteroleptic trinuclear Cu(I) clusters and a Cu(I) coordination polymer (CP) of the formulas [Ag6(dtc)6] 1, [Cu3I2(dppm)3(dtc)] 2, and [Cu(ttc)I]∞ 3 (dtc = N-methylbenzyl-N-methyl-thiophenedithiocarbamate; dppm = 1,1-bis(diphenylphosphino)methane; and ttc = dimethyltrithiocarbonate) were synthesized and characterized by elemental analysis, IR, UV-vis, (1)H, (13)C, and (31)P NMR spectroscopies, and their structures were elucidated by X-ray crystallography. The complexes show interesting structures and luminescent properties. Complex 1, which is centrosymmetric, contains four short Ag···Ag interactions at 2 × 2.966(1) and 2 × 3.014(1) Å. There are also several Ag···Ag distances of 3.3-3.4 Å. The molecule shows hexagonal orientation with alternating silver and sulfur atoms of the overlapping Ag3S3 hexagons in the front and rear, along the a axis. Complex 2 is a rare trinuclear cluster complex of Cu(I); the Cu···Cu distances are 2.906(2), 3.551(2), and 3.338(2) Å, the foremost representing a substantial intermetallic contact. The Cu3I2P6S2 core is comprised of three fused distorted hexagonal rings with the I1 atom located at the center participating in all three rings. Complex 3 is an iodide-bridged CP with a "staircase"-like arrangement in which the Cu(I) is tetrahedrally surrounded by a sulfur atom from the ttc ligand and three iodine atoms. Unlike 3, which is nonluminescent, 1 and 2 are strongly luminescent in the solid and solution at room temperature. The time-resolved emission spectra reveal a triexponential decay curve and short mean lifetime characteristic of fluorescence behavior. Diffuse reflectance spectroscopy revealed semiconducting behavior with band gaps of 2.12, 3.01, and 2.18 eV for 1-3, respectively.