Thermal anal̀ysis of coordination compounds of cobalt (III) with α-dioxime and guanidine derivatives

Dranka, I. V.; Shafranskii, V. N.; Kharitonov, Yu. Ya.

doi:10.1016/0040-6031(85)85033-4

Cited by 2 publications

(3 citation statements)

References 1 publication

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The table lists composition (Tar = C 4 H 4 O 6 2− ), connectivity, bound/free waters, and vol (Å 3 )/mol of metal. We were not able to obtain single-crystal structures of phases 4 and 6 and thus do not know if the waters are bound or free. b Phases 1 , and 5 have been previously described in the literature. c Compound 3 has been previously cited in the literature , and is commercially available (TCI), but no characterization has been reported. …”

Section: Resultsmentioning

confidence: 99%

“… c Compound 3 has been previously cited in the literature , and is commercially available (TCI), but no characterization has been reported. …”

Section: Resultsmentioning

confidence: 99%

“…b Phases 1 27,28 and 5 29 have been previously described in the literature. c Compound 3 has been previously cited in the literature 30,31 and is commercially available (TCI), but no characterization has been reported. identical experimental conditions to the original syntheses but using a lower purity sample of D-tartaric acid, rather than L-tartaric acid, was performed.…”

Section: Hydrothermal Synthesis Of Alkaline Earthmentioning

confidence: 99%

See 2 more Smart Citations

Phase Selection and Energetics in Chiral Alkaline Earth Tartrates and Their Racemic and Meso Analogues: Synthetic, Structural, Computational, and Calorimetric Studies

et al. 2009

View full text Add to dashboard Cite

The hydrothermal reactions of calcium, strontium, and barium with l-, meso-, and d,l-tartaric acid were examined from room temperature to 220 degrees C. We report the synthesis of 13 new phases and crystal structures of 11 alkaline earth tartrates, including an unusual I(3)O(0) framework, [Ba(d,l-Tar)] (Tar = C(4)H(4)O(6)(2-)), with 3-D inorganic connectivity. Each alkaline earth exhibits different phase behavior in the reactions with the three forms of tartaric acid. Calcium forms unique l-, meso-, and d,l-tartrate phases which persist to 220 degrees C. Strontium forms three unique phases at lower temperatures, but above 180 degrees C reactions with l- and d,l-tartaric acid yield the meso phase. Likewise, Ba forms three unique low-temperature phases, but above 200 degrees C reactions with l- and meso-tartaric acid yield the d,l phase. Computational and calorimetric studies of the anhydrous calcium phases, [Ca(l-Tar)] and [Ca(meso-Tar)], strontium phases, [Sr(l-Tar)] and [Sr(meso-Tar)], and barium phases, [Ba(l-Tar)] and [Ba(d,l-Tar)], were performed to determine relative phase stabilities and elucidate the role of thermodynamic and kinetic factors in controlling phase behavior. The computational and calorimetric results were in excellent agreement. The [Ca(meso-Tar)] phase was found to be 9.1 kJ/mol more stable than the [Ca(l-Tar)] phase by computation (total electronic energies) and 2.9 +/- 1.6 kJ/mol more stable by calorimetry (enthalpies of solution). The [Sr(meso-Tar)] phase was found to be 13.4 and 8.1 +/- 1.4 kJ/mol more stable than [Sr(l-Tar)] by computation and calorimetry, respectively. Finally, the [Ba(l-Tar)] phase was found to be 6.4 and 7.0 +/- 1.0 kJ/mol more stable than the [Ba(d,l-Tar)] phase. Our results suggest that the calcium and strontium meso phases are the most thermodynamically stable phases in their systems over the temperature range studied. The phase transitions are controlled by relative thermodynamic stabilities but also by a kinetic factor, likely the barrier to isomerization/racemization of the tartaric acid, which is hypothesized to preclude phase transformations at lower temperatures. In the barium system we find the [Ba(l-Tar)] phase to be the most thermodynamically stable phase at low temperatures, while the [Ba(d,l-Tar)] phase becomes the thermodynamic product at high temperatures, due to a larger entropic contribution.

show abstract