TY - JOUR A1 - Hennig, C. A1 - Takao, S. A1 - Takao, K. A1 - Weiss, S. A1 - Kraus, Werner A1 - Emmerling, Franziska A1 - Scheinost, A.C. T1 - Structure and stability range of a hexanuclear Th(IV)-glycine complex N2 - A hexanuclear Th(IV)–glycine complex was observed by Th L3-edge EXAFS measurements in an aqueous solution. Within the stability range of this complex the positively charged hexanuclear species [Th6(µ3-O)4(µ3-OH)4(H2O)6(Gly)6(HGly)6]6+ was preserved in a crystal with the composition [Th6(µ3-O)4(µ3-OH)4(H2O)6(Gly)6(HGly)6]·(NO3)3(ClO4)3(H2O)3. This complex appears as a result of a competing reaction between hydrolysis and ligation by glycine. At a pH value below the stability range of the hexanuclear complex, crystals with the composition [Th(H2O)3(HGly)3]·(ClO4)4H2O were obtained from the solution. Three water molecules in the thorium coordination sphere indicate that this complex occurs prior to the onset of Th(IV) hydrolysis. PY - 2012 DO - https://doi.org/10.1039/c2dt31367g SN - 1477-9226 SN - 1477-9234 SN - 1364-5447 VL - 41 SP - 12818 EP - 12823 PB - RSC CY - Cambridge AN - OPUS4-27265 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Hennig, C. A1 - Takao, S. A1 - Takao, K. A1 - Weiss, s. A1 - Kraus, Werner A1 - Emmerling, Franziska A1 - Meyer, M. A1 - Scheinost, A.C. T1 - Identification of hexanuclear actinide(IV) carboxylates with thorium, uranium and neptunium by EXAFS spectroscopy N2 - Hydrated actinide(IV) ions undergo hydrolysis and further polymerization and precipitation with increasing pH. The resulting amorphous and partly crystalline oxydydroxides AnOn(OH)4-2n·xH2O can usually be observed as colloids above the An(IV) solubility limit. The aging process of such colloids results in crystalline AnO2. The presence of carboxylates in the solution prevents the occurrence of such colloids by formation of polynuclear complexes through a competing reaction between hydrolysis and ligation. The majority of recently described carboxylates reveals a hexanuclear core of [An6(µ3-O)4(µ3-OH)4]12+ terminated by 12 carboxylate ligands. We found that the An(IV) carboxylate solution species remain often preserved in crystalline state. The An(IV) carboxylates show An–An distances which are ~ 0.03 Å shorter than the An–An distances in AnO2 like colloids. The difference in the distances could be used to identify such species in solution. T2 - XAFS15 - 15th International conference on X-ray absorption fine structure CY - Beijing, China DA - 22.07.2012 KW - Carboxylates KW - EXAFS KW - Actinide PY - 2013 DO - https://doi.org/10.1088/1742-6596/430/1/012116 SN - 1742-6588 SN - 1742-6596 VL - 430 SP - 012116-1 EP - 012116-5 PB - IOP Publ. CY - Bristol, UK AN - OPUS4-28525 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Takao, S. A1 - Takao, K. A1 - Kraus, Werner A1 - Emmerling, Franziska A1 - Scheinost, A.C. A1 - Bernhard, G. A1 - Hennig, C. T1 - First hexanuclear U IV and Th IV formate complexes - Structure and stability range in aqueous solution N2 - The actinide(IV) hexanuclear [M6(μ3-O)4(μ3-OH)4(HCOO)12(LT)6] complexes were prepared (LT = H2O or CH3OH). Their structures were investigated by single-crystal X-ray analysis and XAFS spectroscopy. HCOO– acts as a bridging ligand, which prevents the formation of polynuclear hydrolysis species like UIV hydrous oxide colloids at least up to pH = 3.25, and stabilizes the nanosized clusters in solution. The charge of the hexamer is balanced by the O/OH ratio of the μ3-bridges.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) KW - Actinides KW - Polynuclear species KW - Formic acid KW - Bridging ligands PY - 2009 DO - https://doi.org/10.1002/ejic.200900899 SN - 1434-1948 SN - 1099-0682 VL - 2009 IS - 32 SP - 4771 EP - 4775 PB - Wiley-VCH Verl. CY - Weinheim AN - OPUS4-20329 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Takao, S. T1 - First Hexanuclear U (IV) adn Th (IV) Formate Camplexes - Struture and Stability Range in Aqueous Solution T2 - 3rd EuCheMS Chemistry Congress CY - Nuremberg, Germany DA - 2010-08-29 PY - 2010 AN - OPUS4-21233 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - CONF A1 - Takao, S. T1 - First Hexanuclear U(IV) and Th(IV) Formate Complexes - Structure and Stability Range in Aqueous Solution T2 - 3rd EuCheMS Chemistry Congress CY - Nuremberg, Germany DA - 2010-08-29 PY - 2010 AN - OPUS4-21298 LA - deu AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -