Orthogonal Grade-Separated Nanowiring of Molecular Single Chains

Quasi-one-dimensional (1D) compounds are suitable models to develop future nanodevices. The critical issue is that most of the several hundred reported 1D compounds adopt parallel arrangements. Here, we report the first example of an orthogonal grade-separated arrangement of the halogen-bridged metal complex (MX-Chain) [Pt^II(en)₂][Pt^IVCl₂(en)₂][Fe^IIICl₅]₂, abbreviated as [Pt(en)₂Cl][Fe^IIICl₅] (en = ethylenediamine), which is the first example of that arrangement of molecular single chains. The space group and topology are coincidentally same as alchemists’ gold, Hg_3−δAsF₆, which aligns as atomic single chains. This molecular nanostructure is very rare and valuable as a three-dimensional (3D) nanowiring model. The hydrogen bond network found in [Pt(en)₂Cl][Fe^IIICl₅] represents a new strategy for making such nanostructures. The structural and optical relationships are similar to those of typical Pt(II)/Pt(IV) mixed valent MX-Chains in charge-density-wave (CDW) states. Polarized Raman spectra strongly supported the presence of orthogonal grade-separated chains in CDW states. Thus, this work proved the concept of molecular single-chain grade-separated nanowiring.