Quasi-aromatic Mobius chelates of cadmium(II) nitrite and/or nitrate

We report the design, structural, spectroscopic and computational characterization of the two new quasi-aromatic Mobius chelate coordination compounds fabricated from Cd(NO3)(2)center dot 4H(2)O and a bulky helical organic ligand derived from benzildihydrazone and 2-pyridinecarboxaldehyde (L) in the presence and absence of two equivalents of NaNO2, namely [Cd(NO2)(x)(NO3)(2-x)(L)]center dot 2MeOH (1.2MeOH) and [Cd(NO3)(2)(L)]center dot MeOH (2 center dot MeOH). The former complex was found to extensively lose one of the lattice solvent molecules of methanol under ambient conditions upon isolation from the mother liquor. Therefore, the crystal structure of 1.2MeOH was obtained at 100 K, namely [Cd(NO2)(1.67)(NO3)(0.33)(L)]center dot 2MeOH ((1-100 K)center dot 2MeOH), and at 296 K, namely (Cd(NO2)(1.57)(NO3)(0.43)(L)]center dot 2MeOH ((1-296 K)center dot MeOH). In all the structures, anions exhibit a chelate kappa(2)-O,O-mode. It was found that the reported Cd-NO2 and Cd-NO3 connections are largely ionic in nature, followed by dative covalent charge delocalization and the London dispersion constituents. The electron density of delocalized bonds (EDDB) function and the extended transition state (ETS) energy decomposition method combined with the natural orbitals for chemical valence (ETS-NOCV) have shown sizeable pi-delocalizations within the twisted ligand L suggesting quasi-aromatic Mobius features of the Cd-L chelate. Finally, the optical properties of (1-296 K)center dot MeOH and 2 center dot MeOH have been investigated by diffuse reflectance spectroscopy.