Copper(II) Dihalotetracyanoplatinate(IV) Coordination Polymers and Their Vapochromic Behavior

The coordination polymers [Cu­(H2O)2(μ2-NC)4PtX2] (X = Cl, Br) form networks of square grid sheets that align in a staggered manner with one another via weak X···X interactions. Upon stepwise dehydration, the layers fuse, forming a 3-D network of distorted cubes. The materials were tested for visible vapochromic, Raman, and IR response to dimethyl sulfoxide, N,N-dimethylformamide, and pyridine. Analyte-bound coordination polymers of the form Cu­(analyte)2[PtX2(CN)4] were structurally characterized by PXRD and found to form layers of square grids that align through X···X interactions. The reaction of [Cu­(H2O)2(μ2-NC)4PtX2] with concentrated aqueous NH3 generated [PtBr­(CN)4(NH3)]− and [PtCl­(CN)4(OH)]2– anions that were incorporated into 1-D chain structures. UV–visible reflectance data show that a combination of shifting d–d transitions and the visible Br–Pt LMCT absorption band in [Cu­(H2O)2(μ2-NC)4PtBr2] results in a greater vapochromic effect in comparison to that in chlorine-containing analogues.