Why are hexavalent uranium cyanides rare while U-F and U-O bonds are common and short?

被引：70

作者：

Straka, M ^{[1
]}

Patzschke, M ^{[1
]}

Pyykkö, P ^{[1
]}

机构：

[1] Univ Helsinki, Dept Chem, Helsinki 00014, Finland

来源：

THEORETICAL CHEMISTRY ACCOUNTS | 2003年 / 109卷 / 06期

关键词：

uranium; transition-metal complexes; uranium hexafluoride;

D O I：

10.1007/s00214-003-0441-7

中图分类号：

O64 [物理化学（理论化学）、化学物理学];

学科分类号：

070304 ; 081704 ;

摘要：

Relativistic small-core pseudopotential B3LYP and CCSD(T) calculations and frozen-core PW91-PW91 studies are reported for the series UF4X2 (X = H, F, Cl, CN, NC, NCO, OCN, NCS and SCN). The bonding in UF6 is analyzed and found to have some multiple-bond character, approaching at a theoretical limit a bond order of 1.5. In addition to these sigma and pi orbital interactions, the electrostatic attraction is important. Evidence for pi bonding in the other systems studied was also found. The triatomic pseudohalides as well as fluorine and chlorine are in this sense better ligands than cyanide. The -CN group is a sigma donor and pi acceptor, as uranium itself, and hence is unfit to bond to U(VI). The sigma-bonded UH6 is octahedral.

引用

页码：332 / 340

页数：9

共 65 条

[41] ABINITIO STUDY OF BONDING TRENDS .4. THE 22-ELECTRON A=B=C SERIES - POSSIBLE NEW ANIONS DOWN TO NCB4- AND POSSIBLE NEW CATIONS UP TO FNF3+ [J].