Thermal Behaviour and Room Temperature Crystal Structure of a Bidimensional Complex Salt of 4-Aminocinnamic Acid and Cadmium Chloride

Abstract

The crystal structure at room temperature of the complexe salt 4-aminocinnamic acid cadmium chloride (HOOC‒CH˭CH‒(C₆H₄)‒NH₃)₂ CdCl₄ has been solved by X-ray diffraction method. The structure exhibits bidimensional arrangement with alternated inorganic-organic layers, in a monoclinic symmetry P2₁/m: a = 0.5389(1) nm; b = 3.0165(7) nm; c = 0.6999(3) nm; β = 104.09(3)°. Structural considerations allow to explain the photoinactivity (polymerization) of the compound at room temperature upon irradiation with UV light in contrast to some similar butadiene derivatives which undergo a stereospecific 1,4-addition reaction. Thermal investigations by powder X-ray diffraction and calorimetric methods show during heating process, an exothermic irreversible transformation in the solid state at high temperature concurrently with the disappearance of the tridimensional organization in the structure. A complete interpretation of this phenomenon needs further complementary investigation.

Key Words:

• Bidimensional complex
• Photoreactivity
• Crystal structure