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

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, 1H, 13C, and 31P 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.