Mechanistic Studies on the Reductive Cyclooligomerisation of CO by U(III) Mixed Sandwich Complexes; the Molecular Structure of [(U(η-C₈H₆{SiⁱPr₃-1,4}₂)(η-Cp*)]₂(μ-η¹:η¹-C₂O₂)

Abstract

The stoichiometric reaction of 1 equiv of CO with [(U(eta-C8H6{SiiPr3-1,4}2)(eta-Cp*)] affords the linear diuranium ynediolate complex [(U(eta-C8H6{SiiPr3-1,4}2)(eta-Cp*)]2(mu-eta1:eta1-C2O2) which does not react with further CO to give the deltate derivative [(U(eta-C8H6{SiiPr3-1,4}2)(eta-Cp*)]2(mu-eta1:eta2-C3O3). Spectroscopic and computational studies suggest a plausible mechanism for the formation of the deltate complex, in which a "zig-zag" diuranium ynediolate species is the key intermediate.

UIII‐Induced Reductive Co‐Coupling of NO and CO to Form UIV Cyanate and Oxo Derivates

“…[4] To the best of our knowledge there are no fully substantiated f-element nitrosyl complexes, so we were interested to explore the reactivity of…”

“…Treatment of a toluene solution of [UA C H T U N G T R E N N U N G (h-C 8 H 6 {SiiPr 3 -1,4} 2 )A C H T U N G T R E N N U N G (h-Cp*)] with 1 equivalent of high-purity NO (prepared from NOHSO 4 and Hg [5] ) at À808C and slow warming to room temperature resulted in a colour change of the original green-black solution to red-brown, characteristic of U IV in these mixed sandwich complexes.…”

Homologation and functionalization of carbon monoxide by a recyclable uranium complex

“…The high reduction potentials of low valent f-element complexes suggests a promising approach for the reductive activation of C 1 -small molecules such as CO (19)(20)(21)(22) and CO 2 (23); however, only a handful of f-element complexes can affect the reductive homologation of CO under ambient conditions (24,25). Organometallic uranium complexes can effect reductive homologation of CO to C n -oligomers (n ¼ 2-4) (26)(27)(28), and a small number of uranium triamide and triaryloxide complexes also reductively dimerize CO (29,30). More recently, an organometallic uranium complex was shown to effect the simultaneous reduction and hydrogenation of CO to give a coordinated methoxide that could be liberated as CH 3 OSiMe 3 (31); however, there have been no reports of successful homologation, functionalization, and removal of C n -oligomers (n ≥ 2) under mild conditions with retention of a metal complex that may be recycled for reuse in a synthetic cycle as has been demonstrated for CO 2 (32, 33), P 4 (34), and carbodiimides (35).…”

Facile Conversion of CO/H2 into Methoxide at a Uranium(III) Center

“…Complex [U(h-C 8 H 6 {SiiPr 3 -1,4} 2 )(h-Cp*)] in [D 8 ]toluene was then reacted with one equivalent of 13 CO at À78 8C, allowed to warm briefly (1 min) to 20 8C and then recooled to À78 8C; at this point there is only a trace amount of yne diolate 2 monitored by 13 C NMR spectroscopy, and under these conditions the proposed, relatively long-lived zig-zag intermediate 1 (see Scheme 1) is likely to be the dominant species in solution. [7] Exposure of this solution to dihydrogen also results in the formation of the methoxide 3 as essentially the only 13 COderived product. Thus, we suggest that 3 may arise from hydrogenation of the zig-zag intermediate 1, as opposed to classical hydride reduction of bound CO.…”