Influence of Water Molecules on Properties of Binuclear or Bridged Structures for Chiral CuII-NiII, CuII-PdII, and CuII-PtII Tetracyano- Bimetallic Assemblies

We have prepared new chiral bimetallic assemblies of discrete binuclear [CuL2][Ni(CN)4]·2H2O or onedimensional cyanide-bridged [CuL2][Pd(CN)4] (and [CuL2][Pt(CN)4]) (L = (1S,2S)-(+)-N,N'-dimethyl-cyclohexane-1,2diamine). The numbers of co-crystallized water molecules contained are different from each other and their compositions are easy to vary due to co-crystallized water molecules. As far as we studied on the related [Cu(diamine)2]a [M(CN)b]c·dH2O compounds, actually such a feature has been found for the first time. According to crystal structures, the elongated axial bond distances of [CuL2] 2+ moieties are Cu-N = 2.195(7) Å for [CuL2][Ni(CN)4]·2H2O, Cu-N = 2.443(4) and 2.519(2) Å for [CuL2][Pd(CN)4]. Single crystal structure analyses, variable low temperature XRD, measurements of electronic, CD, emission, and XPS spectra and magnetic properties have been carried out. We compared their structural preference between Ni and Pd (or Pt) metal ions. Novel emission band of [CuL2][Pt(CN)4] appeared at 410 nm ( ex = 360 nm) in the solid state regardless of quenching by cyanide-bridged [CuL2] 2+ moieties.