Exploring the effects of steric factors on the chemistry of lanthanide and actinide complexes.

摘要

This dissertation describes a broad investigation of the chemistry available to a recently discovered class of organometallic uranium complexes that has unusually long bonds and offers new options in developing f element chemistry. This research has resulted in the discovery of new f element reactivity, the isolation of new long bond organometallics, and the synthesis of polymetallic complexes in the nanometer size range that represent the largest supramolecular assemblies of f element metallocenes.; Chapter 1 describes the synthesis of (C5Me4H) 1- containing complexes that provide a basis for comparative studies of (C5Me4H)1- vs. (C 5Me5)1- and allow the special chemistry of long bond organometallics to be better defined.; In Chapter 2, it is shown that uranium borate salts can reduce azides to nitrides and form unprecedented twenty four atom uranium nitrogen ring systems containing alternating uranium nitride and uranium azide linkages. These results represent new strategies for making uranium nitrides and provide a new approach for actinide supramolecular assembly that can be used in the synthesis of nanometer sized compounds called urano-nano particles.; In Chapter 3, optimized procedures based on pre-existing syntheses, are described for the sterically crowded (C5Me5)3M and (C5Me5)3UX complexes. Chapter 4 outlines atom- and time-efficient syntheses of the sterically crowded (C5Me 5)3UCl complex and the first tris(pentamethylcyclopentadienyl) methyl complex, namely (C5Me5)3UMe.; In Chapter 5, the displacements of the methyl substituents from the cyclopentadienyl ring plane are analyzed for the known long bond organometallics and are compared with representative f element complexes. This metric is evaluated as a tool for predicting unusual (C5Me5)1- reactivity.; In Chapter 6, the eta1-alkyl reactivities of f element long bond organometallics with CO as a substrate are compared. The (C 5Me5)3Ln complexes insert CO into the Ln-C(C 5Me5) bonds while, despite steric crowding, (C5Me 5)3U forms a rare example of a uranium carbonyl, (C 5Me5)3U(CO). Adduct formation represents only the third mode of reactivity observed for long bond organometallics. (Abstract shortened by UMI.)