Darlando T. Khathing

First reported synthesis of ammonium hexafluorodioxouranate(VI), (NH4)4[UO2F6]

Abstract Bis(acetylacetonato)dioxouranium(VI) dihydrate, UO2(C5H7O2)2·2H2O, reacts with NH4F in the presence of an excess of acetylacetone and a trace of water to produce (NH4)4[UO2F6] in high yield. The results of chemical analyses, molar conductance, IR and laser Raman spectroscopic studies have been used for characterisation of the compound.

Synthesis and spectroscopic characterization of mixed-fluoro complexes of UO22+ containing amino acids, acetylacetonate or acetate as the co-ligands and the first report on the heptafluoroxioxouranate(VI) complex [UO2F7]5−

Abstract The synthesis of mixed-ligand fluoro complexes of UO 2 2+ of the types A 3 [UO 2 (GlyH) 2 F 5 ] · 3H 2 O [A = K (1) or NH 4 + (2)], K 3 [UO 2 (AlanH) 2 F 5 · 2H 2 O (3), (NH 4 ) 5 [UO 2 (CysH) 2 F 5 ]·2H 2 O (4), [UO 2 (acac)F(H 2 O) 2 ] · 3H 2 O (6), K 2 [UO 2 (acac)F 3 ] (8) and [UO 2 (CH 3 COO)F(H 2 O) 2 ] (9) (GlyH = glycine, AlanH = alanine, CysH − = cysteinate and acac − = acetylacetonate) is described. The complexes have been characterized by a combination of chemical analyses, solution conductance measurements and spectroscopic studies. Vibrational spectroscopy has been used for their structural assessment. Laser Raman spectrum could be recorded only for K 2 [UO 2 (acac)F 3 ] (8), while an extensive fluorescence foiled such attempts on the other complexes. Each of the three amino acid co-ligands acts in a unidentate manner, being coordinated to UO 2 2+ through the caroxylate oxygen atom. While glycine and alanine occur in the zwitter-ionic form, cysteine seems to be present as a uninegative ligand. The reaction of [UO 2 (acac)F(H 2 O) 2 ]·3H 2 O (6) with aqueous HF produced [UO 2 F 2 ] · 3H 2 O (7). Treatment of K 3 [UO 2 (GlyH) 2 F 5 ] · 3H 2 O (1) with water afforded the hitherto unreported potassium heptafluorodioxouranate(VI) dihydrate, K 5 [UO 2 F 7 · 2H 2 O (5), in a high yield with satisfactory ana measurement (590 Ω −1 cm 2 mil −1 ). IR and laser Raman spectra provide clear evidence for the presence of trans -linked OUO and coordinated fluoride. The solution Raman spectrum of 5 is similar to that of its solid indicating that the structure in aqueous solution is the same as the solid. Scanning electron microscopy has been used to ascertain its homogeneity and crystalline nature.

Mass spectrometry of metal compounds. IV. Electron ionisation mass spectra of bis(acetylacetonato)dioxouranium(VI), UO2(C5H7O2)2, and a comparison with those of bis(acetylacetonato) complexes of first row transition metals, M(C5H7O2)2 (M Mn, Fe, Co, Ni, or Cu)

Abstract Electron ionisation mass spectra are reported for the first time for UO 2 (C 5 H 7 O 2 ) 2 , 1 , and the results compared with those of M(C 5 H 7 O 2 ) 2 (M  Mn, Fe, Co, Ni or Cu) recorded under identical experimental conditions. The EI mass spectra of 1 showed a molecular ion signal at m/z 468 without indicating any association in the gaseous state. The molecular ion [UO 2 (C 5 H 7 O 2 ) 2 ] +· loses either CH 3 · and C 4 H 4 O 2 , or OCCH 2 and C 3 H 5 O · to produce [UO 2 (C 5 H 7 O 2 )] + , which undergoes internal reduction to give [UO 2 (C 5 H 7 O 2 )] +· . The radical ion [UO 2 (C 5 H 7 O 2 )] +· suffers a sequential loss of CH 3 · and C 4 H 4 O 2 to produce ultimately the bare species [UO 2 ] + . A comparative account of the results of mass spectrometric studies of 1 and M(C 5 H 7 O 2 ) 2 is presented.

Direct synthesis of tris(acetylacetonato)manganese(III)

A concentrated solution of K[MnO4] undergoes a ready reaction with acetylacetone, in the absence of any buffer, giving a very high yield of the title compound, [Mn(acac)3]. The pH of the solution, recorded immediately after the formation of crystalline [Mn(acac)3], was found to be ca. 5. Electron impact induced mass spectrometry showed the compound to be monometric.

A convenient method for the synthesis of alkali metal pentafluoromanganates(III)

Abstract Reaction of MnO(OH) and a concentrated solution of AHF2 (A = NH4 +, Na+, K+ or Cs+) in 40% hydrofluoric acid gives instantaneously rose-pink coloured alkali metal pentafluoromanganate(III), A2MnF5 (A = NH4 + or Na+), and alkali metal pentafluoromanganate(III) monohydrate, A2MnF5.H2O (A = K+ or Cs+). Li2MnF5 has been synthesised by reacting lithium carbonate with a solution of MnO (OH) in 40% hydrofluoric acid followed by addition of a small amount of alcohol. Characterisation of the compounds and assignment of molecular structure were made from the elemental analyses, chemical determination of oxidation state of manganese in the compounds, magnetic susceptibility measurements and infra red spectral studies.

Synthesis of alkali oxytetrafluorovanadates(V)

Abstract I.R. and 19F N.m.r. spectroscopy, molar conductance, magnetic moments and chemical analyses show that alkali oxytetrafluorovanadates(V), AI[VOF 4], are the principal products of the reactions of V2O5 with 40% HF and alkali bifluorides AIHF2 in presence of a small amount of alcohol at steam bath temperature. While the i.r. spectra suggest square pyramidal C4v structures for solid AI[VOF4], the 19F N.m.r. spectrum shows stereochemical non-rigidity owing to rapid fluorine rearrangement between C4v and the trigonal bipyramidal C2v stereochemistry of [VOF4]− in solution.

The direct synthesis of alkali-metal pentafluoromanganates(III)

The reduction of potassium permanganate with acetylacetone in the presence of an excess of alkali-metal difluoride AHF2(A = NH4, Na, K, or Cs) readily gives pentafluoromanganates(III), A2[-MnF5](A = NH4 or Na) or A2–[MnF5]·H2O (A = K or Cs) in almost quantitative yield. Characterisation of the compounds was made from the results of i.r. spectral studies, chemical analyses, magnetic susceptibility measurements, and chemical determination of oxidation states of manganese in the various compounds.