Thermal expansion, elastic and thermoelastic properties including crystal structure analyses of K-, Rb- and Cs-nitrilotriacetates

Abstract

Abstract Single crystals of the title compounds having optical quality and dimensions up to 60 mm have been grown from aqueous solutions. X-ray crystal structure analyses of K2H[N(CH2COO)3] · H2O (I), K2H[N(CH2COO)3] · 2 H2O (II), and Cs2H[N(CH2COO)3] · H2O (III) has been done. Thermal expansion, elastic and thermoelastic properties of the title compounds have been measured employing mechanical and optical dilatometers and ultrasonic resonance techniques, respectively. They possess quite different structural motifs contrary to most other salts having a common anion. An anomalous large molecular volume and a small mean elastic stiffness of K2H[N(CH2COO)3] · 2 H2O is qualitatively interpreted by the small number of Coulomb interactions between the single charged cations and oxygen atoms of the anions. Differences in thermal and elastic properties of corresponding alkali nitrilotriacetates and alkali salts of other large anions are discussed.