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

Author： Sain Saugata Maji Tapas Kumar Mostafa Golam Lu Tian-Huey Chaudhuri Nirmalendu Ray

ISSN： 0095-8972

Source： Journal of Coordination Chemistry, Vol.56, Iss.13, 2003-09, pp. : 1157-1168

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Abstract

Three new thiocyanato-bridged polymers of cadmium(II), [Cd(me₄dpt)(SCN)₂]_n (1) [me₄dpt = 3,3′-iminobis(N,N-dimethylpropylamine], [Cd(me₂tn)(SCN)₂]_n (2) (me₂tn = 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 1 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 ~ 195°C.