Gasförmige Komplexe von Trichloriden, Tetrachloriden und Pentachloriden mit Aluminiumchlorid

Abstract

Die Gleichgewichte wurden mit den festen Chloriden TiCl3, VCl3, ScCl3, NdCl3, ZrCl4, TaCl5, (NbCl5) gemessen (Doppelzellen mit AlCl3 bzw. MClx; Massenspektrometer). Die Komplexe enthalten 1 AlCl3/MClx. Mit ZrCl4,f wurde auch ZrCl4 · 2 AlCl3 = ZrAl2Cl10,g beobachtet. Messungen mit MoCl3/Al2Cl6 und WCl6/AlCl3 ließen keine Komplexbildung erkennen. Die gewonnenen ΔHº‐ und ΔSº‐Werte wurden im Zusammenhang mit Literaturangaben diskutiert. Auch AlCl3‐reichere Komplexe mit LnCl3 (Ln  Nd, Sm, Gd) wurden in die Diskussion einbezogen.

Thermodynamic Properties of the Rare Earth Element Vapor Complexes LnAl3Cl12 from Ln = La to Ln = Lu

“…Thus, the complexation reactions may generally be expressed as with the equilibrium constant where p°) 0.100 MPa. In the simplest case, where only one complex is formed, the values of n, K p , p Al2Cl6 , and p LnAlnCl3n+3 in eq 2 may be calculated by and [24][25][26][27][28][29][30] where T is the reaction temperature, V is the volume of the ampule, n i and p i are mole number and partial pressure of component i, and K′ p,10 is the equilibrium constant of the dissociation reaction 10 with a special standard pressure of p°′) 0.101 325 MPa.…”

“…While the estimated probable uncertainties may arise from absolute errors of the chemical analysis for Ln 3+ and Clas (0.5%, of the volume measurement of the ampule as (0.5%, and of the temperature measurement as (2.0 K, these uncertainties together with that inherent in eq 9 and the error from the scatter of the experimental points in Figures S1 and 2 may give rise to the probable overall errors of (0.5 kJ mol -1 for ∆G°, (1.5 kJ mol -1 for ∆H°T m , and (2.0 J mol -1 K -1 for ∆S°T m for LnAl 3 Cl 12 from Ln ) La to Ln ) Lu, being the same as those for ScAl 2 Cl 9 and YAl 2 Cl 9 . 30 Moreover, because no experimental data were available for the heat capacities of the vapor complexes, Scha ¨fer 24,38 introduced the estimated values of ∆C p °) -12 J mol -1 K -1 for LnAlCl 6 , ∆C p °) 0 J mol -1 K -1 for LnAl 3 Cl 12 , and ∆C p °) 14 J mol -1 K -1 for LnAl 4 Cl 15 and then Steidl et al 28,29 introduced ∆C p °) -8 J mol -1 K -1 for LnAl 2 Cl 9 . We 30 have assumed an absolute error of (2.0 J mol -1 K -1 for the estimated value of ∆C p °) -8 J mol -1 K -1 for ScAl 2 Cl 9 and YAl 2 Cl 9 .…”

“…In all previous publications, − only the monolanthanide complexes LnAl n Cl 3 n +3 were assumed to be formed; this means that m = 1 in Ln m Al n Cl 3( m + n ) . This assumption may reasonably be extended to Ln = La−Lu in this study.…”

“…Thermodynamic functions of the reactions LnCl 3 (s) + ( n /2)Al 2 Cl 6 (g) = LnAl n Cl 3 n +3 (g) (where Ln = rare earth elements) have been determined for Ln = Nd with n = 1 by mass spectrometric measurements, for Ln = Nd with n = 3 and n = 4 25 and for Ln = Sm with n = 3 by UV−vis spectrometric measurements, for Ln = Gd with n = 3 by entrainment, quenching, and chemical transport experiments, and for Ln = Gd, Tm, and Yb with n = 1−4 by radiochemical analysis. In all the cases, the LnAl 3 Cl 12 complexes were found to be the predominant vapor complexes in the temperature range 500−900 K for Ln = Nd, Sm, Gd, , Tm, and Yb …”

AlNbBr8 – Preparation, Crystal Structure, and Vapor Pressure Studies

“…Coordination to AlCl 4 – was used to stabilize dumbbell‐like Cd 2 2+ in Cd 2 (AlCl 4 ) 2 9. As for pentahalides, M AlCl 8 ( M = U, Ta) exist in gas phase 19,20. Yellow crystalline AlNbCl 8 , prepared from NbCl 5 and AlCl 3 at 200 °C was shown to contain dinuclear Cl 4 Nb(μ‐Cl 2 AlCl 2 ) molecules, consisting of an AlCl 4 tetrahedron and a NbCl 6 octahedron sharing a common edge 21.…”