Thermochemical Study Of Adducts Of Urea With Zinc, Cadmium And Mercury: Some Correlations For Urea Derivatives

The adducts ZnX2·2ur (X = Cl, Br, I), CdX2·2ur (X = Br, I), CdX2· ur (X = Cl, Br, I) and HgX2 ur (X = Cl, Br) have been characterized. The shifts of the stretching vibrations to low frequency (vCO) and to high frequencies (vCN and vNH) indicated that urea (ur) is oxygen-bonded to the metals. The standard molar enthalpies for the reaction MX2(c)+ nur(c) = MX2· nur(c) ΔrHm ⊖ were determined by solution-reaction calorimetry, given the following values: ZnCl2 ·2ur(c), -59.72±0.30; ZnBr2 · 2ur, -59.41±0.89; ZnI2 · 2ur, -81.74 ±0.89; CdCl2 · ur, -21.54±0.18; CdBr2 · ur, -13.88±0.28; CdI2 · ur, -30.75±0.36; CdBr2 · 2ur, -24.40+0.21; CdI2 · 2ur, -19.69±0.17; HgCl2 · ur, -9.39±0.13 and HgBr2 · ur, +1.00 ±0.78 kJ mol-1. From these values, the standard molar enthalpies of formation (ΔfHm ⊖) and of decomposition (ΔDHm ⊖), and lattice enthalpy (ΔMHm ⊖) were calculated and the mean molar enthalpy of the metal-oxygen bond [t̄D(M-O)] was estimated. The thermochemical results indicate a decrease in stability of the adducts from zinc to mercury. The degree of hydrogen bonding affects differently the enthalpies of formation of adducts in solid state for urea and its derivatives. © 1988.125C295305Pryor, Sanger, Collection and interpretation of neutron diffraction measurements on urea (1970) Acta Crystallographica Section A, 26 A, p. 543Penland, Mizushima, Curran, Quagliano, (1957) J. Am. Chem. Soc., 79, p. 1575Laulight, Pinchas, Petreanu, Samuel, The infra-red absorption spectrum of 18O-labelled urea (1965) Spectrochimica Acta, 21, p. 1487Novak, Hydrogen bonding in solids correlation of spectroscopic and crystallographic data (1974) Struct. Bonding, 18, p. 177Liapis, Jayasooriya, Kettle, Eckert, Goldstone, Taylor, (1985) J. Chem. Phys. Chem., 89, p. 4560Robinson, Jenkens, (1965) J. Am. Chem. Soc., 87, p. 2462Holtzer, Emerson, (1969) J. Phys. Chem., 73, p. 26Lindqvist, (1963) Inorganic Adduct Molecules of Oxo-Compounds, , Springer-Verlag, BerlinNeubauer, Kerner, Ueber das Guanin (1857) Annalen der Chemie und Pharmacie, 101, p. 340Kumler, Fohlen, (1942) J. Am. Chem. Soc., 64, p. 1944Nardelli, Braibanti, Chierici, (1957) Gazz. Chim. Ital., 87, p. 1226Nardelli, Cavalea, Fava, (1957) Gazz. Chim. Ital., 87, p. 1232Lebioda, On the geometry of urea–cation bonding in crystalline urea adducts (1980) Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry, 36 B, p. 271Pearson, (1963) J. Am. Chem. Soc., 85, p. 3533Antonenko, Nuger, (1966) Russ. J. Inorg. Chem., 11, p. 578Lewinski, Sliwinski, Lebioda, (1983) Inorg. Chem., 22, p. 2339Airoldi, Chagas, Assunção, Thermochemical study of adducts of tetramethylurea with zinc, cadmium, and mercury halides (1980) Journal of the Chemical Society, Dalton Transactions, p. 1823Airoldi, Chagas, Assunção, Thermochemical study of adducts of methylurea with zinc, cadmium, and mercury halides (1982) Canadian Journal of Chemistry, 60, p. 2132Assunção, Chagas, Airoldi, (1982) J. Chim. Phys., 79, p. 253Burkinshaw, Mortimer, (1983) Coord. Chem. Rev., 48, p. 101Jorge, Airoldi, Chagas, Thermochemistry of dichlorobis(triphenylphosphine oxide)-zinc(II), -cadmium(II), and -mercury(II) (1978) Journal of the Chemical Society, Dalton Transactions, p. 1102Airoldi, Silva, Chagas, Heterocyclic nitrogen-containing electron-pair donor ligands: a thermochemical study of adducts with zinc, cadmium, and mercury chlorides (1986) Journal of the Chemical Society, Dalton Transactions, p. 1913de Queiroz, Airoldi, Chagas, Thermochemical data for adducts of zinc, cadmium, and mercury halides with hexamethylphosphoramide (1985) Journal of the Chemical Society, Dalton Transactions, p. 1103Rao, Chaturvedi, Gosavi, (1968) J. Mol. Spectrosc., 28, p. 526Mido, (1976) Spectrochim. Acta, 32 A, p. 1105Maslowska, Cedzynska, (1973) J. Mol. Struct., 19, p. 521Wilson, Worral, (1969) J. Inorg. Nucl. Chem., 31, p. 1357Aggarwal, Singh, (1964) J. Inorg. Nucl. Chem., 26, p. 2185Aggarwal, Singh, (1965) J. Inorg. Nucl. Chem., 27, p. 2597Jensen, (1980) The Lewis Acid-Base Concepts—An Overview, , Wiley, New YorkAshcroft, Beech, (1973) Inorganic Thermodynamics—An Introduction to the Thermodynamics of Inorganic and Organometallic Compounds, , Van Nostrand-Reinhold, New YorkBarnes, Duncan, Complexes of some alkali-metal and silver salts with 1,4-dioxan (1972) Journal of the Chemical Society, Dalton Transactions, p. 1732de Oliveira, Chagas, Airoldi, (1983) Inorg. Chem., 22, p. 136Airoldi, (1981) Inorg. Chem., 20, p. 99