gasosa os óxidos de actinídeos
equação 3.14 e também ΔH f [CmO 2+ ] = 2068±60 kJ.mol 1 através da equação 3.20.
3.4 Relação entre actinilos em fase gasosa e em fase aquosa
3.4.3 Estabilidade intrínseca de AnO 22+
A estabilidade intrínseca dos iões actinilos relativamente às forças de Coulomb, definidas de acordo as equações 3.35 e 3.36, pode ser determinada com base nos valores determinados até agora.
3.35 3.36
Para o processo da equação 3.35 ser endotérmico e o processo de dissociação em {An+ + O 2+}
termodinamicamente desfavorável, é necessário que
3.37
ou
3.38
Usando
EI[O2] = 12,07 eV,43
os limites inferiores de D[OAn+-O] determinados acima,
D[An+-O] ≥ 752 kJ.mol-1 para An = Pa, U e Np,
D[Pu+-O] ≥ 632 kJ.mol-1
e os valores deste trabalho para EI[AnO2+],
conclui-se que PaO22+, UO22+, NpO22+ e PuO22+ são estáveis relativamente a {An+ + O2+} em 5,9 eV,
6,6 eV, 4,8 eV e 3,5 eV, respectivamente.
Para a equação 3.36 ser endotérmica e a dissociação em {AnO+ + O+} desfavorável é necessário
que 3.39 + + + → + 2 2 2 An O AnO ] O [ H ] An [ H ] AnO [ H 2 f f 2 2 f + ≤Δ + +Δ + Δ ]} + + + →AnO +O AnO2 2 0 ] AnO [ EI ] O O [ D ] O [ EI ] O An [ D ] O OAn [ D +− + +− + 2 − − − 2+ > O [ H ] AnO [ H { ] AnO [ H 2 f f 2 f + ≤ Δ + +Δ + Δ
138
3.40
Usando
EI[O] = 13,618 eV,43
o limite inferior de D[OU+-O] ≥ 632 kJ.mol-1
e o valor estimado neste trabalho EI[UO2+] = 14,6 eV,
conclui-se que UO22+ é estável relativamente a {UO++O+} em pelo menos 5,6 eV.
Da mesma forma, no caso de Pa, usando D[OPa+-O] ≥ 751 kJ.mol-1
e EI[PaO2+] ≈ 16,6 eV,
e para Np e Pu
D[OAn+-O] ≥ 498 kJ.mol-1
e EI[AnO2+] ≈ 15,1 eV
conclui-se que estes actinilos são estáveis relativamente a {AnO++O+} por 4,8 eV e 3,7 eV,
respectivamente.
UO22+ é o mais estável dos actinilos, seguido de PaO22+. De um modo geral, a dissociação de
AnO22+ em {AnO+ + O+} é mais favorável energeticamente do que a dissociação em {An+ + O2+},
uma vez que a ligação An2+-O é mais forte que a ligação ao segundo oxigénio.
A explosão de Coulomb é um processo para o qual o papel não definido da entropia na química de iões em fase gasosa a baixas pressões pode ser importante.98,99 Se as entropias de AnO
22+,
AnO+ e An+ forem comparáveis, então as variações de entropia associadas à dissociação de
Coulomb vão ser dominadas pela formação do ião de oxigénio atómico, -T.S[O+] = -46 kJ.mol-1 (-
0,48 eV) a 298 K100 ou do ião molecular –T.S[O
2+] = -61 kJ.mol-1 (-0,64 eV) a 298 K100.95 Mesmo
que se incluam as possíveis desestabilizações entrópicas, de 0,5 ou 0,6 eV, os actinilos continuam a ser termodinamicamente estáveis à temperatura ambiente.
Para estimar a EI[AmO2+] e a estabilidade do ião AmO22+ pode usar-se a termoquímica da fase
aquosa. A ionização de AnO2+ hidratado é descrita pela equação
3.41
A entalpia da reacção acima, definida por
3.42
é para cada um dos actinídeos estudados 0 ] AnO [ EI ] O [ EI ] O OAn [ D + − + − 2+ > − + +(aq)→AnO (aq)+e AnO 2 2 2 )] aq ( AnO [ H )] aq ( AnO [ H H 2 f 2 2 f r =Δ + −Δ + Δ
ΔHr[UO2+] = 0,15±0,07 eV23
ΔHr[NpO2+] = 1,21±0,07 eV23
ΔHr[PuO2+] = 0,96±0,09 eV23
ΔHr[AmO2+] = 1,59±0,05 eV23
Se se considerar que a variação de entalpia de hidratação, ΔHhyd[AnO22+] - ΔHhyd[AnO2+], é
praticamente constante para todos os actinilos, então EI[UO2+] será ~1,06±0,10 eV menor que
EI[NpO2+] e ~0,81±0,11 eV menor que EI[PuO2+]. Dos resultados da transferência electrónica na
fase gasosa concluiu-se que a diferença de EI[UO2+] é 0,5±0,6 eV para ambos EI[NpO2+] e
EI[PuO2+] (secção 3.3.5.). Assim, os resultados na fase aquosa estão de acordo com a tendência
dos valores obtidos na fase gasosa, EI[UO2+] < EI[NpO2+] ≈ EI[PuO2+]. Seguindo o mesmo
raciocínio, EI[AmO2+] será 0,6 eV maior que EI[PuO2+], estimando-se EI[AmO2+] = 15,7±0,9 eV,
onde a elevada incerteza reflecte eventuais variações na entalpia de hidratação. Desta estimativa de EI[AmO2+] e da estimativa acima para ΔHf[AmO2+(g)] = 410±50 kJ.mol-1, conclui-se
que ΔHf[AmO22+(g)] = 1924±100 kJ.mol-1. Este valor está de acordo com o obtido
(ΔHf[AmO22+(g)] ≈ 1896 kJ.mol-1), assumindo que ΔHhyd[AmO22+ ] ≈ -1670 kJ.mol-1. A concordância
dos dois valores reforça a conclusão que ΔHhyd[AnO22+] ≈ 1670 kJ.mol-1 para An = U, Np, Pu e
Am.
Usando EI[AmO2+] = 15,7 eV
D[OAm+-O] ≥ 354 kJ.mol-1 e
D[Am+-O] ≥ 532 kJ.mol-1
prevê-se que AmO22+ seja estável em relação a {Am+ + O2+} em 0,4 eV (de acordo com a equação
3.38) e a {AmO+ + O+} em pelo menos 1,6 eV (equação 3.40). Usandos as estimativas de D[OAm+-
O] = 390 kJ.mol-1 e D[Am+-O] = 560 kJ.mol-1 em vez dos limites inferiores, vem então que
AmO22+ será estável em 2 eV em relação a {AmO+ + O+} e em 1 eV em relação a {Am+ +O2+}.
Considerando a incerteza de 0,9 eV no valor de EI[AmO2+] e a possibilidade de desestabilização
entrópica até 0,6 eV, AmO22+ continua a ser estável relativamente à dissociação em AmO+ + O+
mas a estabilidade relativamente a Am+ + O
2+ continua incerta.
3.5 Conclusões
Os estudos descritos neste capítulo permitiram obter diversos dados termoquímicos que contribuem para o melhor conhecimento dos iões de óxidos de actinídeos. Observaram-se pela primeira vez na fase gasosa NpO22+, PuO22+ e também PaO22+ que não é conhecido na fase
140
condensada. PaO22+ e CmO2+, ambos em estados de oxidação pouco comuns, catalisaram a
oxidação de CO por N2O. Determinaram-se vários valores de energias de dissociação ao oxigénio
e verificaram-se alguns valores já existentes na literatura. De um modo geral, a força das ligações ao oxigénio diminui ao longo da série de actinídeos, de acordo com a acessibilidade a configurações electrónicas com dois electrões não f desemparelhados. Foram também estimadas as energias de ionização para os diversos óxidos de actinídeos estudados, que permitiram corrigir ou aconselhar alguns valores da literatura. As energias de ionização mostram uma tendência de aumento ao longo da série de acordo com a diminuição da estabilidade de estados de oxidação elevados. Estes dados mostraram ser úteis para estudos da fase aquosa pois permitiram determinar experimentalmente as entalpias de hidratação dos vários AnO2+ e AnO22+.
1. Cornehl HH, Wesendrup R, Diefenbach M, Schwarz H. A Comparative Study of Oxo-Ligand Effects in the Gas-Phase Chemistry of Atomic Lanthanide and Actinide Cations. Chemistry - A European Journal. 1997;3(7):1083-1090.
2. Jackson GP, King FL, Goeringer DE, Duckworth DC. Gas-Phase Reactions of U+ and U2+ with O 2 and
H2O in a Quadrupole Ion Trap. Journal of Physical Chemistry A. 2002;106(34):7788-7794.
3. Liang B, Hunt RD, Kushto GP, Andrews L, Li J, Bursten BE. Reactions of Laser-Ablated Uranium Atoms with H2O in Excess Argon: A Matrix Infrared and Relativistic DFT Investigation of Uranium
Oxyhydrides. Inorganic Chemistry. 2005;44(7):2159-2168.
4. Martin WC, Zalubas R, Hagan L. Atomic Energy Levels: The Rare-Earth Elements. 60.º ed. Washington, DC: National Bureau of Standards (NIST); 1978.
5. Lavrov VV, Blagojevic V, Koyanagi GK, Orlova G, Bohme DK. Gas-Phase Oxidation and Nitration of First-, Second-, and Third-Row Atomic Cations in Reactions with Nitrous Oxide: Periodicities in Reactivity. Journal of Physical Chemistry A. 2004;108(26):5610-5624.
6. Heinemann C, Schwarz H. NUO+, a New Species Isoelectronic to the Uranyl Dication UO
22+.
Chemistry - A European Journal. 1995;1(1):7-11.
7. Cornehl HH, Heinemann C, Marçalo J, Pires de Matos A, Schwarz H. The Bare Uranyl(2+) Ion, UO22+. Angewandte Chemie International Edition in English. 1996;35:891-894.
8. Schroder D, Schwarz H. Generation, Stability, and Reactivity of Small, Multiply Charged Ions in the Gas Phase. Journal of Physical Chemistry A. 1999;103(37):7385-7394.
9. Zhou M, Andrews L. Infrared spectra and pseudopotential calculations for NUO+, NUO, and NThO
in solid neon. The Journal of Chemical Physics. 1999;111(24):11044-11049.
10. Gibson JK. Reactions of actinide ions with ethylene oxide. Journal of Mass Spectrometry.
2001;36(3):284-293.
11. Gibson JK. Gas-phase chemistry of actinide ions: probing the distinctive character of the 5f elements. International Journal of Mass Spectrometry. 2002;214(1):1-21.
12. Gibson JK, Haire RG, Marçalo J, Santos M, Pires de Matos A, Mrozik MK, Pitzer RM, Bursten BE. Gas-phase reactions of hydrocarbons with An+ and AnO+ (An = Th, Pa, U, Np, Pu, Am, Cm): The
active role of 5f electrons in organoprotactinium chemistry. Organometallics. 2007;26(16):3947- 3956.
13. Goncharov V, Kaledin LA, Heaven MC. Probing the electronic structure of UO+ with high-
resolution photoelectron spectroscopy. The Journal of Chemical Physics. 2006;125(13):133202-8. 14. Goncharov V, Heaven MC. Spectroscopy of the ground and low-lying excited states of ThO+. The
Journal of Chemical Physics. 2006;124(6):064312-7.
15. Katz JJ, Seaborg GT, Morss LR. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz JJ, Seaborg GT, Morss LR, Eds.; 1986:1121-1195.
16. Armentrout PB, Beauchamp JL. Reactions of U+ and UO+ with O
2, CO, CO2, COS, CS2 and D2O.
Chemical Physics. 1980;50(1):27-36.
17. Santos M, Marcalo J, de Matos AP, Gibson JK, Haire RG. Gas-phase oxidation reactions of neptunium and plutonium ions investigated via Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. Journal of Physical Chemistry A. 2002;106(31):7190-7194.
18. Santos M, Marçalo J, Leal JP, Pires de Matos A, Gibson JK, Haire RG. FTICR-MS study of the gas- phase thermochemistry of americium oxides. International Journal of Mass Spectrometry.
2003;228(2-3):457-465.
19. Weigel F. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz JJ, Seaborg GT, Morss L R, Eds.; 1986:169-442.
20. Fahey J. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz JJ, Seaborg GT, Morss LR, Eds.; 1986:443-498.
21. Weigel F, Katz JJ, Seaborg GT. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz JJ, Seaborg GT, Morss L R, Eds.; 1986:499-886.
22. Schulz WW, Penneman RA. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz J J, Seaborg GT, Morss L R, Eds.; 1986:887-961.
23. Morss LR. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz, J. J., Seaborg, G. T., Morss, L. R., Eds.; 1986:1278-1360.
24. Lias SG, Bartmess JE, Liebman JF, Holmes JL, Levin RD, Mallard WG. Gas-phase ion and neutral thermochemistry. Washington, DC: American Chemical Society; 1988.
25. Carretas JM, Pires de Matos A, Marçalo J, Pissavini M, Decouzon M, Geribaldi S. Gas-phase reactivity of rare earth cations with phenol: competitive activation of C–O, O–H, and C–H bonds. Journal of the American Society for Mass Spectrometry. 1998;9(10):1035-1042.
26. Armentrout PB. Guided ion beam studies of transition metal–ligand thermochemistry. International Journal of Mass Spectrometry. 2003;227(3):289-302.
27. Koyanagi GK, Bohme DK. Oxidation Reactions of Lanthanide Cations with N2O and O2:
Periodicities in Reactivity. Journal of Physical Chemistry A. 2001;105(39):8964-8968.
28. Katzin JJ. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz, J. J., Seaborg, G. T., Morss, L. R., Eds.; 1986:41-101.
29. Kirby HW. Em: The Chemistry of the Actinide Elements. 2.ª ed. Chapman and Hall: New York: Katz, J. J., Seaborg, G. T., Morss, L. R., Eds.; 1986:102-168.
30. Santos M, Pires de Matos A, Marçalo J, Gibson JK, Haire RG, Tyagi R, Pitzer RM. Oxidation of Gas-Phase Protactinium Ions, Pa+ and Pa2+: Formation and Properties of PaO
22+(g), Protactinyl.
Journal of Physical Chemistry A. 2006;110(17):5751-5759.
31. Straka M, Dyall KG, Pyykkö P. Ab initio study of bonding trends for f0 actinide oxyfluoride species. Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta). 2001;106(6):393-403.
32. Roth LM, Freiser BS. Gas-phase chemistry and photochemistry of doubly charged transition- metal containing ions. Mass Spectrometry Reviews. 1991;10(4):303-328.
33. Hildenbrand D, Gurvich L, Yungman V. The Chemical Thermodynamics of Actinide Elements and Compounds. Part 13. The Gaseous Actinide Ions. Vienna: International Atomic Energy Agency; 1985. 34. Schroder D, Schwarz H, Harvey JN. LaO+: A Diatomic Cation with a Sizable Proton Affinity upon
Generation of the LaOH2+ Dication. Journal of Physical Chemistry A. 2000;104(48):11257-11260.
35. Lide DR. CRC Handbook of Chemistry and Physics. 75.ª ed. Boca Raton: CRC Press; 1994:2608. 36. Schröder D, Engeser M, Schwarz H, Harvey JN. Energetics of the Ligated Vanadium Dications VO2+, VOH2+, and [V,O,H
2] 2+. ChemPhysChem. 2002;3(7):584-591.
37. Dai P, McCullough-Catalano S, Bolton M, Jones AD, Lebrilla CB. Charge stripping of ligated metal ions. International Journal of Mass Spectrometry and Ion Processes. 1995;144(1-2):67-77.
38. Kappes MM, Staley RH. Gas-phase oxidation catalysis by transition-metal cations. Journal of the American Chemical Society. 1981;103(5):1286-1287.
39. Bohme DK, Schwarz H. Gas-Phase Catalysis by Atomic and Cluster Metal Ions: The Ultimate Single-Site Catalysts. Angewandte Chemie International Edition. 2005;44(16):2336-2354.
40. Blagojevic V, Orlova G, Bohme DK. O-Atom Transport Catalysis by Atomic Cations in the Gas Phase: Reduction of N2O by CO. Journal of the American Chemical Society. 2005;127(10):3545-
3555.
41. Bronstrup M, Schroder D, Kretzschmar I, Schwarz H, Harvey JN. Platinum Dioxide Cation: Easy to Generate Experimentally but Difficult to Describe Theoretically. Journal of the American Chemical Society. 2001;123(1):142-147.
42. Lias SG, Bartmess JE, Liebman JF, Holmes JL, Levin RD, Mallard WG. J. Phys. Chem. Ref. Data.
1988;Suppl. 1:17.
43. NIST Chemistry Webbook-NIST Standard Reference Database Number 69. 2005. Available at: http://webbook.nist.gov/chemistry/.
44. Kleinschmidt PD, Ward JW. Thermochemical studies on the plutonium fluorides and protactinium oxides. Journal of the Less Common Metals. 1986;121:61-66.
45. Sugar J. Ionization energies of the neutral actinides. The Journal of Chemical Physics.
1973;59(2):788-791.
46. Gibson JK. Laser Ablation Mass Spectromety of Actinide Dioxides: ThO2, UO2, NpO2, PuO2 and
AmO2. Radiochimica Acta . 1998;81:83-91.
47. Gibson JK, Haire RG. Gas-phase chemistry of bare and oxo-ligated protactinium ions: a contribution to a systematic understanding of actinide chemistry. Inorganic Chemistry.
2002;41(22):5897-5906.
48. Gibson JK. Role of Atomic Electronics in f-Element Bond Formation: Bond Energies of Lanthanide and Actinide Oxide Molecules. Journal of Physical Chemistry A. 2003;107(39):7891-7899.
49. Becker JS, Dietze H. Oxide ion formation of long-lived radionuclides in double-focusing sector field inductively coupled plasma mass spectrometry and their analytical applications. International Journal of Mass Spectrometry. 2000;202(1-3):69-79.
50. Haire RG. Comparison of the chemical and physical properties of f-element metals and oxides: their dependence on electronic properties. Journal of Alloys and Compounds. 1995;223(2):185-196. 51. Ackerman RJ, Fairclot RL, Rauh EG, Thorn RJ. Evaporation behaviour of neptunium dioxide. Journal of Inorganic & Nuclear Chemistry. 1966;28(1):111.
52. Capone F, Colle JY, Hiernaut JP, Ronchi C. Mass Spectrometric Measurement of the Ionization Energies and Cross Sections of Uranium and Plutonium Oxide Vapors. Journal of Physical Chemistry A. 1999;103(50):10899-10906.
53. Cornehl HH, Wesendrup R, Harvey JN, Schwarz H. Oxo ligand as a reactivity switch in gas-phase ion chemistry of the lanthanides. Journal of the Chemical Society, Perkin Transactions 2.
1997;(11):2283-2292.
54. Zemski KA, Bell RC, CastlemanJr. AW. Reactivities of tantalum oxide cluster cations with unsaturated hydrocarbons. International Journal of Mass Spectrometry. 1999;184(2-3):119-128. 55. Han J, Kaledin LA, Goncharov V, Komissarov AV, Heaven MC. Accurate ionization potentials for UO and UO2: A rigorous test of relativistic quantum chemistry calculations. Journal of the American
Chemical Society. 2003;125(24):7176-7177.
56. Han J, Goncharov V, Kaledin LA, Komissarov AV, Heaven MC. Electronic spectroscopy and ionization potential of UO2 in the gas phase. Journal of Chemical Physics. 2004;120(11):5155-5163.
57. Goncharov V, Han J, Kaledin LA, Heaven MC. Ionization energy measurements and electronic spectra for ThO. The Journal of Chemical Physics. 2005;122(20):204311-6.
58. Trautmann N. Accurate determination of the first ionization potential of actinides by laser spectroscopy. Journal of Alloys and Compounds. 1994;213-214:28-32.
59. Worden EF, Carlson LR, Johnson SA, Paisner JA, Solarz RW. Ionization potential of neutral atomic plutonium determined by laser spectroscopy. Journal of the Optical Society of America B.
1993;10(11):1998.
60. Sugar J. Revised ionization energies of the neutral actinides. The Journal of Chemical Physics.
1974;60(10):4103.
61. Lias SG, Rosenstock HM, Draxl K, Steiner BW, Herron JT, Holmes JL, Levin RD, Liebman JF, Kafafi SA. Ionization Energetics data. Em: NIST Chemistry Webbook-NIST Standard Reference Database Number 69. Eds. P.J. Linstrom and W.G. Mallard. Gaithersburg MD: National Institute of Standards and Technology; 2003. Available at: http://webbook.nist.gov/chemistry/.
62. Ackermann RJ, Rauh EG, Thorn RJ. The thermodynamics of ionization of gaseous oxides; the first ionization potentials of the lanthanide metals and monoxides. The Journal of Chemical Physics.
1976;65(3):1027-1031.
63. Dyke JM, Ellis AM, Feher M, Morris A, Paul AJ, Stevens J. High-temperature photoelectron spectroscopy. A study of niobium monoxide and tantalum monoxide. Journal of the Chemical Society, Faraday Transactions 2. 1987;83(8):1555-1565.
64. Freiser BS. Chapter 4. Em: Bonding Energetics in Organometallic Compounds. Marks TJ, Eds. Washington, DC: American Chemical Society; 1990.
65. Zimmerman JA, Bach SBH, Watson CH, Eyler JR. Ion/molecule reactions of arsenic and phosphorus cluster ions: ionization potentials and novel reaction pathways. Journal of Physical Chemistry. 1991;95(1):98-104.
66. Freiser BS. Gas-phase Metal Ion Chemistry. Journal of Mass Spectrometry. 1996;31(7):703-715.
67. Heinemann C, Cornehl HH, Schroder D, Dolg M, Schwarz H. The CeO2+ Cation: Gas-Phase
Reactivity and Electronic Structure. Inorganic Chemistry. 1996;35(9):2463-2475.
68. Ervin KM. Experimental Techniques in Gas-Phase Ion Thermochemistry. Chemical Reviews.
2001;101(2):391-444.
69. Capone F, Colle JY, Hiernaut JP, Ronchi C. Controversy on the First Ionization Potential of PuO2
(Nearly) Settled by New Experimental Evidence. Journal of Physical Chemistry A.
2005;109(51):12054-12058.
70. Sidorov LN, Zhuravleva LV, Sorokin ID. High-temperature mass spectrometry and studies of ion- ion, ion-molecule, and molecule-molecule equilibria. Mass Spectrometry Reviews. 1986;5(1):73-97. 71. Abramov SV, Chilingarov NS, Rau JV, Borschevsky AY, Sidorov LN. Formation of the negative cluster ions in a Knudsen cell at low temperatures. International Journal of Mass Spectrometry.
2005;245(1-3):90-93.
72. Ronchi C, Capone F, Colle JY, Hiernaut JP. Volatile molecule PuO3 observed from subliming
plutonium dioxide. Journal of Nuclear Materials. 2000;280(1):111-115.
73. Gagliardi L, Malmqvist PA, Roos BO, Dyke JM. On the Electronic Structure of the UO2 Molecule.
Journal of Physical Chemistry A. 2001;105(46):10602-10606.
74. Rauh EG, Ackermann RJ. First ionization potentials of some refractory oxide vapors. The Journal of Chemical Physics. 1974;60(4):1396-1400.
75. Dyke JM, Fayad NK, Morris A, Trickle IR, Allen GC. A study of the electronic structure of the actinide tetrahalides UF4, ThF4, UCl4 and ThCl4 using vacuum ultraviolet photoelectron spectroscopy
and SCF-X alpha scattered wave calculations. The Journal of Chemical Physics. 1980;72(6):3822- 3827.
76. Hill YD, Huang YQ, Ast T, Freiser BS. Study of the gas-phase chemistry of Y2+ with small alkanes.
Rapid Communications in Mass Spectrometry. 1997;11(1):148-154.
77. Spears KG, Fehsenfeld GC, McFarland M, Ferguson EE. Partial Charge-Transfer Reactions at Thermal Energies. The Journal of Chemical Physics. 1972;56(6):2562-2566.
78. Petrie S, Javahery G, Wang J, Bohme DK. Selected-ion flow tube study of charge transfer from fullerene dications: "bracketing" the second ionization energies of C60 and C70. Journal of Physical
Chemistry. 1992;96(15):6121-6123.
79. Petrie S, Wang J, Bohme DK. Charge transfer from polycharged ions: C60n+ as a model system.
Chemical Physics Letters. 1993;204(5-6):473-480.
80. Bohme DK. Electron-transfer reactions with buckminsterfullerene, C60, in the gas-phase.
International Reviews in Physical Chemistry. 1994;13(2):163-185 .
81. Scheier P, Duenser B, Maerk TD. Charge Separation Processes of Multiply-Charged Fullerene Ions C60-2mz+, with 0 ≤ m ≤ 7 and 3 ≤ z ≤ 7. Journal of Physical Chemistry. 1995;99(42):15428-15437.
82. Senn G, Mark TD, Scheier P. Charge separation processes of highly charged fullerene ions. The Journal of Chemical Physics. 1998;108(3):990-1000.
83. Roithová J, Schröder D. Substituent effects on the second ionization energies of hydroxy- and methoxy benzenes. International Journal of Mass Spectrometry. 2007;267(1-3):134-138.
84. Marcus Y. Some thermodynamic data concerning the dioxouranium(VI) ion and its compounds and reactions. Journal of Inorganic and Nuclear Chemistry. 1975;37(2):493-501.
85. Zhou M, Andrews L, Ismail N, Marsden C. Infrared Spectra of UO2, UO2+, and UO2- in Solid Neon.
Journal of Physical Chemistry A. 2000;104(23):5495-5502.
86. Majumdar D, Balasubramanian K, Nitsche H. A comparative theoretical study of bonding in UO2++, UO2+, UO2, UO2−, OUCO, O2U(CO)2 and UO2CO3. Chemical Physics Letters. 2002;361(1-2):143-
151.
87. Moskaleva LV, Matveev AV, Kruger S, Rosch N. The Heat of Formation of the Uranyl Dication: Theoretical Evaluation Based on Relativistic Density Functional Calculations. Chemistry - A European Journal. 2006;12(2):629-634.
88. Moskaleva LV, Matveev AV, Dengler J, Rosch N. The heat of formation of gaseous PuO22+ from
relativistic density functional calculations. Physical Chemistry Chemical Physics. 2006;8(32):3767- 3773.
89. Spencer S, Gagliardi L, Handy NC, Ioannou AG, Skylaris CK, Willetts A, Simper AM. Hydration of UO22+ and PuO22+. Journal of Physical Chemistry A. 1999;103(12):1831-1837.
90. Hay PJ, Martin RL, Schreckenbach G. Theoretical Studies of the Properties and Solution Chemistry of AnO22+ and AnO2+ Aquo Complexes for An = U, Np, and Pu. Journal of Physical
Chemistry A. 2000;104(26):6259-6270.
146
91. Marcus Y, Loewenschuss A. Standard thermodynamic functions of the gaseous actinyl ions MO2n+
and for their hydration. Journal of the Chemical Society, Faraday Transactions 1. 1986;82(9):2873- 2886.
92. Rizkalla EN, Choppin GR. Lanthanides and actinides hydration and hydrolysis. Em: Handbook on the Physics and Chemistry of Rare Earths.Vol 18: Lanthanides/Actinides: Chemistry. Gschneidner KA; Jr Eyring L; Choppin GR; Lander GH, Eds. Amsterdam: North Holland; 1994:529-558.
93. Tupitsyn I. Uranium ionization-potentials calculated by the relativistic Hartree-Fock-Dirac method taking into account configuration-interaction. Soviet Radiochemistry. 1991;33(5):511-515. 94. Halliwell HF, Nyburg SC. Enthalpy of hydration of the proton. Transactions of the Faraday Society. 1963;59:1126-1140.
95. Tissandier MD, Cowen KA, Feng WY, Gundlash E, Cohen MH, Earhart AD, Coe JV, Tuttle TR. The Proton's Absolute Aqueous Enthalpy and Gibbs Free Energy of Solvation from Cluster-Ion Solvation Data. Journal of Physical Chemistry A. 1998;102(40):7787-7794.
96. Moskaleva LV, Kruger S, Sporl A, Rosch N. Role of Solvation in the Reduction of the Uranyl Dication by Water: A Density Functional Study. Inorganic Chemistry. 2004;43(13):4080-4090.
97. Burgess J. Metal ions in solution. John Wiley and Sons. New York: distributed by Halsted Press;
1978:175-228.
98. Irikura KK. The Ionization Energy of CF3: When Does Entropy Matter in Gas-Phase Reactions?
Journal of the American Chemical Society. 1999;121(33):7689-7695. 99. Ferguson EE, Miller TM, Viggiano AA. The reaction HCl+ + CF
4--> HCF4+ + Cl: Implications for the
heat of formation of CF3+. The Journal of Chemical Physics. 2003;118(5):2130-2134.
100. Chase MW, Davies CA, Downey DJ, Frurip DJ, McDonald RA, Syverud AN. Journal of Physical Chemistry Reference Data. 1985;14, Supplement 1.
Introdução
1
Reactividade
de iões de actinídeos em fase gasosa
O papel dos electrões 5f
2
Termoquímica
de iões de actinídeos em fase gasosa
Os óxidos de actinídeos
3
Caracterização
de vidros contendo actinídeos
A importância da força das ligações metal-oxigénio
4
Conclusões e Perspectivas
5
149