Comparative investigation of the solution species [U(CO)] and the crystal structure of Na[U(CO)]12HO
四価ウランの溶存炭酸錯体([U(CO)])及び単結晶炭酸錯体(Na[U(CO)]12HO)の比較検討に関する研究
Hennig, C.*; 池田 篤史 ; Emmerling, F.*; Kraus, W.*; Bernhard, G.*
Hennig, C.*; Ikeda, Atsushi; Emmerling, F.*; Kraus, W.*; Bernhard, G.*
単結晶X線回折及びX線吸収分光法を用いて、溶液中及び単結晶固体中における四価ウランの炭酸錯体の構造を解明し、その錯体構造の違いを比較検討した。その結果、生成した単結晶はNa[U(CO)]12HOの構造を有し、中心構造である陰イオン性の骨格構造[U(CO)]は溶液中でも保持されていること、単結晶中では対陽イオンのNa+は[U(CO)]単位構造を架橋する役割を果たしているのに対し、溶液中ではNa+はより[U(CO)]錯体に近接しているらしいこと等が明らかになった。
The coordination of the limiting U(IV) carbonate species in aqueous solution was investigated by comparing its structure parameters with those of the complex preserved in a crystal structure. The U(IV) carbonate complex in the crystal structure was identified as a [U(CO)] anionic complex. This monomeric anion complex forms a network with charge compensating Na+ cations and HO ligands. U L3-edge EXAFS spectra were collected from the solid Na[U(CO)]12HO and the corresponding solution. The obtained data indicate the identity of the [U(CO)] complex in solid and solution states. The high negative charge of the [U(CO)] anionic complex is compensated by Na+ cations. In the solid state the Na+ cations form a bridging network between the [U(CO)] anion complex, while in the liquid state they seem to be located closer at the anionic complex anion.