Isoreticular Tp*-W-Cu-S Cluster-Based One-Dimensional Coordination Polymers with an Uncommon [tp*ws3cu2] + [cu] Combination and Their Third-Order Nonlinear Optical Properties

We herein report three isoreticular Tp*-W-Cu-S cluster-based one-dimensional coordination polymers, namely, [Tp*WS3Cu2(CN) 2Cu].pz) 0.5 (2), [Tp* WS3Cu2.CN) 2Cu].bipy) 0.5 center dot 0.5DMF (3), and [Tp* WS3Cu2.CN) 2Cu].bpb) 0.5 center dot DMF (4), from the reaction of [Et4N].Tp* WS3] (1) with CuCN in the presence of bridging ligands pyrazine (pz), 4,4'-bipyridine (bipy), and 1,4-bis.4-pyridyl) benzene (bpb) under solvothermal conditions. In 2-4, a pair of butterfly-shaped [Tp* WS3Cu2](+) clusters are connected by two [Cu.CN) 2]-units to give a macrocyclic unit, which is further strung by pz/bipy/bpb to give linear chains. Besides their rare isoreticular nature, 2-4 are also unique in that they contain a [Tp* WS3Cu2](+) [Cu] combination instead of the widely acknowledged nest-shaped [Tp* WS3Cu3](2+) or cuboidal [Tp* WS3Cu3X](+) (X = Cl, Br, I) cluster skeleton. Compounds 2-4 are also characterized by FT-IR, elemental analysis, UV-vis and ESI-MS. The ESI-MS results also indicate that the pz/bipy/bpb coordination is labile in solution under harsh ionization conditions, yielding CN-ligated anionic species which are assumed as the key contributors to the enhanced NLO performance of 2-4 compared to that of the starting material 1.