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Title: Thermal-stability of Some Potassium Dibenzo-18-crown-6 Solid Compounds - Kx(db18c6) (x = Ncs, Br, I, No3) - Differential Scanning Calorimetry and X-ray-investigations
Authors: A., Bianchi
J., Giusti
P., Paoletti
Mangani, Stefano 
Keywords: x-ray; macrocycle; DSC
Issue Date: 1986
Project: None 
The thermal stability of the compounds KX(DB- 18C6) (X = NCS, Br, I, NO3; DB18C6 = dibenzo-18- crown-6) has been determined by differential scanning calorimetry. Only the KNCS(DB18C6) complex melts congruently; the iodide and the nitrate compounds, when melting, undergo a partial dissociation into their components. The compound KI(DB18C6)- C2H5OH, when heated, loses the ethanol molecule without any dissociation. A KBr(DB18C6)3CHCl3 compound was isolated; it dissociates into its components by evaporation of the solvate molecules. Crystals of the compounds KNCS(DB18C6) are monoclinic, space group P21/n with a = 19.107(8), b = 27.085(5),c = 8.559(5) Å, β = 101.96(4),° and Z = 8. The structure was solved by the heavy atom method. Refinement of the atomic parameters by least-squares gave a final R factor of 0.127 (Rw = 0.116). The structure consists of independent complex molecules of KNCS(DB18C6) in which the potassium ion is coordinated by the six oxygen atoms of the crown ether and by the nitrogen atom of the thiocyanate ion.
ISSN: 0020-1693
DOI: 10.1016/S0020-1693(00)82192-1
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