ABSTRACT

The mass spectra of tetrakis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)lanthanide(III)-potassium complexes KLn(C5HF6O2)4, where Ln = La, Gd, Lu, (hereinafter referred to as KLn(hfa)4), have been recorded at different temperatures. The presence of the high-intensity ions KLn(hfa)3 + generated by elimination of one ligand from the parent species due to electron ionization indicates that the saturated vapours of all three complexes consist of the only KLn(hfa)4 species. The sublimation enthalpies were determined by effusion Knudsen method in frame of second law of thermodynamics. The vaporization was studied over temperature ranges 414 471 R for KLa(hfa)4, 401 453 R for KGd(hfa)4, and 399 442 R for KLu(hfa)4. The values of DsubH (T) equal 170.6 +- 2.1, 166.4 +- 3.6, and 161.8 +- 2.3 kJ/mol for the complexes of La, Gd and Lu respectively. DFT/PBE0 calculations show, that the shortening of theMAO bond length due to lanthanide contraction is accompanied by a decrease in the negative net charge on the oxygen atoms bounded with potassium. The potassium ions play the role of the bridges between the [Ln(hfa)4] anions in the crystal, and weakening the KAO ionic bonds can explain the decrease in the enthalpy of sublimation of the lutetium complex in comparison with the lanthanum one.

Compounds

#	Formula	Name
1	C20H4F24KLaO8	potassium tetrakis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)lanthanate(III)
2	C20H4F24GdKO8	potassium tetrakis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)gadolinate(III)
3	C20H4F24KLuO8	potassium tetrakis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)lutetate(III)

Datasets

The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type	Compound-#	Property	Variable	Phase	Method	#Points
POMD	1	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Derived by Second law	1
POMD	2	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Derived by Second law	1
POMD	3	Molar enthalpy of vaporization or sublimation, kJ/mol ; Crystal	Temperature, K; Crystal	Crystal Gas	Derived by Second law	1

Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

Sublimation enthalpy of tetrakis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)lanthanide(III)-potassium complexes, KLn(C5HF6O2)4: Effect of lanthanide contraction

Khochenkov, A. E.[Aleksey E.], Belova, N. V.[Natalya V.], Krasnov, A. V.[Alexander V.], Zhabanov, Y. A.[Yuriy A.], Giricheva, N. I.[Nina I.], Girichev, G. V.[Georgiy V.]

ABSTRACT