Structure and Bonding

This volume reviews recent developments in the ?elds of organometallic and coordination chemistry of the actinides, and in particular uranium. Actinide chemistryingeneralhasrecentlybeenrejuvenatedwithdemonstrationsof- precedented structures, reactivity, and physical properties. While organou- nium chemistry can be traced back to the Manhattan Project, most of these efforts were unsuccessful. However, by the mid-1950s the ?rst uranium - clopentadienyl (Cp) complexes were being reported, e. g. tricyclopentadienyl uranium(IV) chloride, (C H ) UCl. The late1960s heralded thesynthesis and 5 5 3 structural elucidation of uranocene, bis(cyclooctatetraenyl)uranium(IV), U(C H ), an expanded-ring sandwich compound that provided tantalizing 8 8 2 evidence that 5f orbitals might be involved in bonding. One of the chapters in this volume details the expansion of this kind of work to include mixed sandwich U(III) cyclooctatetraene and pentalene complexes. As discussed by several of the authors, the availability of easily prepared mid-valent sta- ing materials has been one of the primary factors involved in reinvigorating this ?eld. Of particular interest to many readers will be the binding of small molecules by both organometallic and coordination compounds of uranium. Some of the holy grails of this chemistry include the activation of dinitrogen, carbon monoxide, and carbon dioxide. Various aspects of this work can be foundinallthreechapters, butaredetailedinparticularbyO. T. Summerscales andF. G. N. Cloke. The origins of coordination compounds of uranium are dif?cult to de?ne precisely because thede?nition of what constitutes acoordination compound versus apurelyinorganiccompoundcanbedif?culttodifferentiate. However, the coordination chemistry of uranium is very old, dating back to at least the early1800s."