Enriquez Alejandro E, Scott Brian L, Neu Mary P
Actinide, Catalysis, and Separations Chemistry (C-SIC), Chemistry Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Inorg Chem. 2005 Oct 17;44(21):7403-13. doi: 10.1021/ic050578f.
The synthesis of complexes used to elucidate an understanding of fundamental An(III) and An(IV) coordination chemistry requires the development of suitable organic-soluble precursors. The reaction of oxide-free uranium metal turnings with 1.3 equivalents of elemental iodine in acetonitrile provided the U(III)/U(IV) complex salt, [U(N[triple bond]CMe)9][UI6][I] (1), in which the U(III) cation is surrounded by nine acetonitrile molecules in a tricapped trigonal prismatic arrangement, a [UI6]2- counterion, and a noncoordinating iodide. The U-N distances for the prismatic and capping nitrogens are 2.55(3) and 2.71(5) A, respectively. The same reaction performed in benzonitrile afforded crystalline UI4(N[triple bond]CPh)4 (3) in 78% isolated yield. In the solid state, 3 shows an eight-coordinate U(IV) atom in a "puckered" square antiprismatic geometry with U-N and U-I distances of 2.56(1) and 3.027(1) A, respectively. This benzonitrile UI4 adduct is a versatile U(IV) synthon that is soluble in methylene chloride, benzonitrile, and tetrahydrofuran, and moderately soluble in toluene and benzene, but decomposes in benzonitrile at 198 degrees C to [UI(N[triple bond]CPh)8][UI]6 (4), a U(III)/U(IV) salt analogous to 1. A toluene slurry of 3 treated with 2.2 equiv of CpMgCl.THF (Cp = pentamethylcyclopentadienide) provided Cp2UI2(N[triple bond]CPh) (5) in low yields. Single-crystal X-ray structure determination shows that the iodide ligands in 5 are in a rare cis configuration with an acute I-U-I angle of 83.16(7) degrees . Treatment of a methylene chloride solution of 3 with KTp (Tp* = hydridotris(3,5-dimethylpyrazolylborate)) formed green TpUI3 (6) which was converted to yellow TpUI3(N[triple bond]CMe) (7) by rinsing with acetonitrile. Addition of 2.2 equiv of KTp to a toluene solution of 3 followed by heating at 95 degrees C, filtration, and crystallization led to the isolation of the dinuclear species [TpUI(dmpz)]2[mu-O] (9) (dmpz = 3,5-dimethylpyrazolide), presumably formed by hydrolytic cleavage of excess KTp by adventitious water. The Tp* complexes 6, 7, and 9 were characterized by single-crystal X-ray diffraction, NMR, FT-IR, and optical absorbance spectroscopies.
用于阐明对An(III)和An(IV)基本配位化学理解的配合物的合成需要开发合适的有机可溶性前体。无氧化物的铀金属屑与1.3当量的单质碘在乙腈中反应得到U(III)/U(IV)配合物盐[U(N≡CMe)9][UI6][I] (1)，其中U(III)阳离子被九个乙腈分子以三帽三棱柱排列包围，一个[UI6]2-抗衡离子和一个非配位碘化物。棱柱形和帽状氮原子的U-N距离分别为2.55(3)和2.71(5) Å。在苯甲腈中进行相同反应，以78%的分离产率得到结晶的UI4(N≡CPh)4 (3)。在固态中，3显示一个八配位的U(IV)原子，呈“褶皱”的四方反棱柱几何构型，U-N和U-I距离分别为2.56(1)和3.027(1) Å。这种苯甲腈UI4加合物是一种通用的U(IV)合成子，可溶于二氯甲烷、苯甲腈和四氢呋喃，中度溶于甲苯和苯，但在198℃时在苯甲腈中分解为[UI(N≡CPh)8][UI]6 (4)，一种类似于1的U(III)/U(IV)盐。用2.2当量的CpMgCl·THF (Cp = 五甲基环戊二烯基)处理3的甲苯浆液，以低产率得到Cp2UI2(N≡CPh) (5)。单晶X射线结构测定表明，5中的碘化物配体处于罕见的顺式构型，I-U-I锐角为83.16(7)°。用KTp (Tp* = 氢化三(3,5-二甲基吡唑基)硼酸盐)处理3的二氯甲烷溶液，形成绿色的TpUI3 (6)，通过用乙腈冲洗将其转化为黄色的TpUI3(N≡CMe) (7)。向3的甲苯溶液中加入2.2当量的KTp，然后在95℃加热、过滤和结晶，得到双核物种[TpUI(dmpz)]2[μ-O] (9) (dmpz = 3,5-二甲基吡唑化物)，推测是由偶然的水对过量KTp的水解裂解形成的。通过单晶X射线衍射、NMR、FT-IR和光吸收光谱对Tp*配合物6、7和9进行了表征。
