Three new thiocyanato-bridged complexes of cadmium(II): Syntheses, X-ray crystal structures and thermal properties

Three new thiocyanato-bridged polymers of cadmium(II), [Cd(me(4)dpt)(SCN)(2)](n) (1) [me(4)dpt=3,3'-iminobis(N,N-dimethylpropylamine)], [Cd(me(2)tn)(SCN)(2)], (2) (me(2)tn=N,N'-dimethyl-1,3-propanediamine) and [{amphyH} {Cd(SCN)(3)}](n) (3) (ampyH=4-aminopyridinium cation), have been synthesized and their molecular structures determined through X-ray crystallography. In Complex I each square pyramidal mononuclear fragment is H-bonded (N-H...S) to form a 1D supramolecular chain. Complex 2 is a 1D coordination polymer in which each distorted octahedral cadmium(II) ion is linked with the four bridging thiocyanates and one diamine. The structure of 3 reveals anionic [Cd(SCN)(3)](-) zigzag chains arranged in an approximately hexagonal array with the 4-aminopyridinum cations occupying triangular channels. Each chain is H-bonded (N-H...N) to form a 2D supramolecular network. Upon heating, 1 and 2 melt and transform to transparent solid masses at ambient temperature over a few days. On scratching, these turn to a fine powder. This phenomenon is repeatable. Complex 3 upon heating loses a 4-aminopyridine molecule and transforms to [H][Cd(SCN)3] at similar to195degreesC.