Copper Halide-Bridged Ruthenium Telluride Carbonyl Complexes: Discovery of the Semiconducting Cluster Chain Polymer {[PPh4]2[Te2Ru4(CO)10Cu4Br2Cl2]⋅THF}

A new series of Te–Ru–Cu carbonyl complexes was prepared by the reaction of K2TeO3 with [Ru3(CO)12] in MeOH followed by treatment with PPh4X (X=Br, Cl) and [Cu(MeCN)4]BF4 or CuX (X=Br, Cl) in MeCN. When the reaction mixture of K2TeO3 and [Ru3(CO)12] was first treated with PPh4X followed by the addition of [Cu(MeCN)4]BF4, doubly CuX‐bridged Te2Ru4‐based octahedral clusters [PPh4]2[Te2Ru4(CO)10Cu2X2] (X=Br, [PPh4]2[1]; X=Cl, [PPh4]2[2]) were obtained. When the reaction mixture of K2TeO3 and [Ru3(CO)12] was treated with PPh4X (X=Br, Cl) followed by the addition of CuX (X=Br, Cl), three different types of CuX‐bridged Te–Ru carbonyl clusters were obtained. While the addition of PPh4Br or PPh4Cl followed by CuBr produced the doubly CuBr‐bridged cluster 1, the addition of PPh4Cl followed by CuCl led to the formation of the Cu4Cl2‐bridged bis‐TeRu5‐based octahedral cluster compound [PPh4]2[{TeRu5(CO)14}2Cu4Cl2] ([PPh4]2[3]). On the other hand, when the reaction mixture of K2TeO3 and [Ru3(CO)12] was treated with PPh4Br followed by the addition of CuCl, the Cu(Br)CuCl‐bridged Te2Ru4‐based octahedral cluster chain polymer {[PPh4]2(Te2Ru4(CO)10Cu4Br2Cl2)⋅THF}∞ ({[PPh4]2[4]⋅THF}∞) was produced. The chain polymer {[PPh4]2[4]⋅THF}∞ is the first ternary Te–Ru–Cu cluster and shows semiconducting behavior with a small energy gap of about 0.37 eV. It can be rationalized as resulting from aggregation of doubly CuX‐bridged clusters 1 and 2 with two equivalents of CuCl or CuBr, respectively. The nature of clusters 1–4 and the formation and semiconducting properties of the polymer of 4 were further examined by molecular orbital calculations at the B3LYP level of density functional theory. A series of Te–Ru–Cu carbonyl clusters based on octahedral Te2Ru4 cores and containing bridging copper halide moieties was synthesized by reaction of K2TeO3 with [Ru3(CO)12] followed by treatment with PPh4X and [Cu(MeCN)4]BF4 or CuX (X=Br, Cl) in MeOH/MeCN. The products include the novel chain polymer {[PPh4]2[Te2Ru4(CO)10Cu4Br2Cl2]⋅THF}∞ (shown here), which has semiconducting properties with a small band gap of approximately 0.37 eV.