Syntheses, structures and properties of two coordination polymers of Cadmium(II) pseudohalide containing an in situ generated bidentate Schiff base: Control of dimensionality by varying pseudohalides
Two neutral coordination polymers of Cadmium(II) pseudohalide of the type [Cd(LL)(μ₁, ₅-dca) ₂]n (1) and [Cd(LL)(μ₁, ₃-NCS) ₂] n (2) (LL = phenyl(pyridin-2-yl)methanimine and dca = dicyanamide) have been isolated using a 1:1:1:2 molar ratio of CdCl₂.H₂O, 2-aminopyridine (ap), 2-benzoylpyridine (bp) and Na(dca)/NH₄SCN in alcoholic solvent at room temperature. X-ray structural study reveals that in the condensation reaction of ap and bp some degradation occurs in presence of the metal ion to afford an in situ generated bidentate Schiff base (LL) in the complexed form. Each Cadmium(II) center in both 1 and 2 adopts an octahedral geometry with a CdN₆ chromophore in 1 and a CdN4S₂ chromophore in 2. In 1, each metal(II) center is connected to four other metal(II) centers through four different μ₁, ₅-dca bridges affording a three-dimensional network structure, whereas each Cd(II) center in 2 is linked with neighbouring Cd(II) centers through bibridged end-to-end (EE) thiocyanates to form a non-ending linear 1D zig-zag chain. Further, in crystalline state 1D chains in 2 are stabilized through weak intermolecular C-H…S hydrogen bond interaction promoting 2D sheet structure. Thermally stable compounds 1 and 2 show intraligand 1(π-π∗) fluorescence in DMF solution at room temperature.
Volume 134, 2022
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