Suppression of Realgar Cage Degradation during Complexation: Formation of Hybrid Coordination Polymers with As4S4, PAs3S3, and Cu(I) Halide Building Blocks

Realgar, As4S4, reacts with Cr­(CO)5THF under cage degradation to give As4S3·Cr­(CO)5 (1). The reverse structural change is found if solutions of 1 in CH2Cl2 react with equimolar amounts of PAs3S3·W­(CO)5 and CuX (X = Cl, Br, I) in CH3CN under biphasic diffusion conditions. The resulting coordination polymers 2–4 contain a reconstituted realgar molecule along with the PAs3S3 cage. The crystal structures of (CuX)­(As4S4)­(PAs3S3) (X = Cl: 2; Br: 3) are characterized by one-dimensional (1D) (CuX)­(As4S4) strands, which are formed by alternating As4S4 cages and CuX dumbbells. Terminal PAs3S3 molecules are coordinated to copper by apical phosphorus and bridging realgar through sulfur. The As3 triangles of the resulting (CuX)­(As4S4)­(PAs3S3) strands interact with halides of neighbored strands to give a folded three-dimensional (3D) network. The structure of (CuI)3(As4S4)­(PAs3S3) (4) contains 1D (Cu3I3)n strands as backbones, which are bridged by sulfur atoms of two η1:2-As4S4 molecules while PAs3S3 confines the resulting sheet. The As3 triangles at the surface of the layers interact with iodide of the next layer to form a layered 3D network.