Tsoureas Nikolaos, Kilpatrick Alexander F R, Inman Christopher J, Cloke F Geoffrey N
School of Life Sciences , Division of Chemistry , University of Sussex , Falmer , Brighton , BN1 9QJ , UK . Email:
Chemistry Research Laboratory , Department of Chemistry , University of Oxford , 12 Mansfield Road , OX1 3TA , Oxford , UK.
Chem Sci. 2016 Jul 1;7(7):4624-4632. doi: 10.1039/c6sc00632a. Epub 2016 Apr 11.
The synthesis and molecular structures of a U(v) neutral terminal oxo complex and a U(v) sodium uranium nitride contact ion pair are described. The synthesis of the former is achieved by the use of BuNCO as a mild oxygen transfer reagent, whilst that of the latter is the reduction of NaN. Both mono-uranium complexes are stabilised by the presence of bulky silyl substituents on the ligand framework that facilitate a 2e oxidation of a single U(iii) centre. In contrast, when steric hindrance around the metal centre is reduced by the use of less bulky silyl groups, the products are di-uranium, U(iv) bridging oxo and (anionic) nitride complexes, resulting from 1e oxidations of two U(iii) centres. SQUID magnetometry supports the formal oxidation states of the reported complexes. Electrochemical studies show that the U(v) terminal oxo complex can be reduced and the [U(iv)O] anion was accessed reduction with K/Hg, and structurally characterised. Both the nitride complexes display complex electrochemical behaviour but each exhibits a quasi-reversible oxidation at -1.6 V Fc.
描述了一种U(V)中性末端氧络合物和一种U(V)钠铀氮化物接触离子对的合成及其分子结构。前者的合成是通过使用BuNCO作为温和的氧转移试剂实现的，而后者是通过NaN的还原得到的。两种单铀络合物都通过配体骨架上存在庞大的硅基取代基而得以稳定，这些取代基促进了单个U(III)中心的2e氧化。相比之下，当通过使用体积较小的硅基减少金属中心周围的空间位阻时，产物是二铀、U(IV)桥连氧和（阴离子）氮化物络合物，这是由两个U(III)中心的1e氧化产生的。超导量子干涉仪磁力测量法支持所报道络合物的形式氧化态。电化学研究表明，U(V)末端氧络合物可以被还原，并且通过K/Hg还原得到了[U(IV)O]阴离子，并对其进行了结构表征。两种氮化物络合物都表现出复杂的电化学行为，但每种在-1.6 V Fc处都表现出准可逆氧化。
