The First Observation of One-Dimensional Naphthalenediimidato-Based Transition-Metal Coordination Polymers: Syntheses, Crystal Structures and Properties

Metal-directed assembly of naphthalene-1,4,5,8-tetracarboxylic acid (NTA) with different transition-metal salts in the presence of ammonia results in a series of one-dimensional metal–naphthalenediimidato (M–NDI) coordination polymers with the formulas of {[Ag­(NDI)]­(NH4)}n (P1), [Zn­(NDI)­(NH3)2]n (P2), [Cd­(NDI)­(NH3)2]n (P3), [Co­(NDI)­(NH3)2]n (P4) and [Ni­(NDI)­(NH3)2]n (P5), respectively. It is worthwhile to mention that the 1D straight-line NDI–Ag­(I) coordination polymer P1 is formed stepwise from a dinuclear NDI–Ag­(I) intermediate [Ag2(NDI)­(NH3)2] (2AgNDI), where ammonia serves as a stabilizing reagent of Ag­(I) ion and a weak base to remove the protons of NDIH2 simultaneously. Furthermore, P1 exhibits semiconducting properties in the solid state which may originate from its all-parallel-aligned packing structure (AAAA) which is different from the common ABAB packing mode for P2–P5 and 2AgNDI. In addition, theoretic computational studies as well as X-ray photoelectron spectrometer spectra on P1 and 2AgNDI have also been carried out.