State of Water in Inorganic Crystal Hydrates and the Characteristic Features of Their Dehydration

Step-by-step pattern of thermal dissociation of coordination compounds

“…It is true that it has been noted [4] that the reconstruction of a mixed aqua polyhedron during dehydration would invalidate conclusions about the difference in the water bonding energies in the starting hydrate on the basis of the thermogravimetric pattern of the stepwise dehydration, but nevertheless it is also stated in this book that the dehydration temperature depends on the strength of the water bonding; in the hydrates of salts, the freedom of movement is higher for the uncoordinated water molecules than for the coordinated ones, and this must give rise to a lower temperature of their removal. It is noted that, if there is a transition from a pure aqua complex (polyhedron with high symmetry) to a mixed aqua-acido complex (polyhedron with low symmetry), the bond energy increases only for some of the water molecules, and this can be the cause of the step-by-step dehydration [4].…”

“…It is noted that, if there is a transition from a pure aqua complex (polyhedron with high symmetry) to a mixed aqua-acido complex (polyhedron with low symmetry), the bond energy increases only for some of the water molecules, and this can be the cause of the step-by-step dehydration [4].…”

Standard Enthalpies of Formation of Neodymium(III) and Erbium(III) Succinates and Malates

“…The IR spectra of carboxylic acids contain absorption bands at 175031680 cm !1 , characteristic of protonated carboxy groups, while the spectra of neodymium(III) and erbium(III) succinates and malates lack these bands and show bands at 150031590 cm !1 characteristic of asymmetric vibrations of COO ! groups, which suggests formation of neutral salts [3]. The complexes of neodymium(III) and erbium(III) malates contain two bands at 10803 1010 cm !1 , that are lacking in the spectra of malic acid and can be assigned, according to [4], to stretching vibrations of the OH !…”

“…The standard enthalpies of formation of neodymium(III) and erbium(III) malates are more exothermic, which is probably connected with the nature of the ligand [3,5].…”

“…We prepared dehydrated complexes of rare-earth metals with succinic and malic acids, such as Nd 2 (C 4 H 4 O 4 ) 3 , Er 2 (C 4 H 4 O 4 ) 3 , Nd 2 (C 4 H 4 O 5 ) 3 , and Er 2 (C 4 H 4 O 5 ) 3 . The IR spectra of carboxylic acids contain absorption bands at 175031680 cm !1 , characteristic of protonated carboxy groups, while the spectra of neodymium(III) and erbium(III) succinates and malates lack these bands and show bands at 150031590 cm !1 characteristic of asymmetric vibrations of COO !…”