Organoactinide chemistry: synthesis, structure, and solution dynamics
The trivalent uranium coordination complexes (RC/sub 5/H/sub 4/)/sub 3/U-L (R = H, Me, SiMe/sub 3/) have been prepared to study the relative basicity of donor ligands toward low-valent uranium. It is found that the relative order of increasing basicity is PMe/sub 3/ > P(OR)/sub 3/ greater than or equal to py > SR/sub 2/ approx. = OR/sub 2/ NR/sub 3/. The series is found to be measurably sensitive to the steric and electronic properties of the metal coordination sphere as well as electronic perturbations of the donor ligand. A combination of data from solution measurements, crystallographic analysis, and gas phase PES, leads to the conclusion that trivalent uranium engages in a considerable degree of M ..-->.. L ..pi..-backbonding toward ligands such as CO, CNR, PR/sub 3/, and P(OR)/sub 3/. Electronic saturation of the metal enhances this interaction. The trivalent uranium complexes CP/sub 3/ U-L reduce PhNCO, CS/sub 2/, SCO, and YPR/sub 3/ (Y = S, Se, Te) to form the (IV) complexes (Cp/sub 3/U)/sub 2/(X) (X = Y, CS/sub 2/, PhNCO). The reaction between Cp/sub 3/U and C/sub 8/H/sub 8/ or O/sub 2/ results in isolation of ligand redistribution products: in the C/sub 8/H/sub 8/ reaction, (C/sub 8/H/sub 8/)U(Me/sub 3/SiC/sub 5/H/sub 4/)/sub 2/ has been isolated, while in the O/sub 2/ reaction, (Me/sub 3/SiC/sub 5/H/sub 4/)/sub 4/U has been isolated and structurally characterized; all Cp rings are eta/sup 5/-coordinated to the metal. In the presence of organic azides, trivalent uranium acts as a two electron reducing agent to form U(V) imides X/sub 3/U = NR (X = Cp, (Me/sub 3/Si)/sub 2/N). The ..mu..-imido dimers (Cp/sub 3/U = NR)/sub 2/ (R = Ph, SiMe/sub 3/) have been isolated from the reaction of Cp/sub 3/UNR and Cp/sub 3/U. The Ph compound contains an asymmetric bridge with single and double U-N bonds, while the SiMe/sub 3/ complex is symmetrically bridged.
- Research Organization:
- California Univ., Berkeley (USA)
- OSTI ID:
- 7042820
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ORGANOMETALLIC COMPOUNDS
MOLECULAR STRUCTURE
SYNTHESIS
URANIUM COMPLEXES
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
STABILIZATION
ACTINIDE COMPLEXES
COMPLEXES
KINETICS
ORGANIC COMPOUNDS
REACTION KINETICS
400201* - Chemical & Physicochemical Properties