Carbon Dioxide Reduction and Carbon Monoxide Activation Employing a Reactive Uranium(III) Complex

Abstract

The highly reactive, six-coordinate tris-aryloxide U(III) species, [((t-BuArO)3tacn)U] (1) reacts with CO2 in a 2e- reduction to produce CO and a dinuclear U(IV/IV) mu-oxygen bridged complex [{((t-BuArO)3tacn)U}2(mu-O)] (2). This reaction proceeds via a dinuclear CO2-bridged intermediate 3. Also, mononuclear 1 was treated with 1 atm of CO to yield dinuclear [{((t-BuArO)3tacn)U}2(mu-CO)] (4) with a CO ligand bridging two uranium ions in an unprecedented mu:eta1,eta1 fashion. The mixed-valent azido-bridged U(III/IV) complex 5 was synthesized from trivalent 1 and tetravalent [((t-BuArO)3tacn)U(N3)] and serves as an isostructural analogue of triatomic-bridged intermediate 3 as well as an electronic model for mixed-valent 4.

Homologation and functionalization of carbon monoxide by a recyclable uranium complex

“…Conversion of CO to allene has been demonstrated, but five steps are required to close a multicomponent H 2 ∕CO∕ benzyl∕Me 3 SiOTf∕Me 3 SiCl∕PhCH 2 MgCl synthetic cycle (18). 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).…”

Synthesis of a Stable Disilyne Bisphosphine Adduct and Its Non‐Metal‐Mediated CO2 Reduction to CO

“…The reaction readily affords the disilyne bisphosphine adduct 2, which can be isolated as red crystals (13 % yield). In the 29 Si NMR spectrum, derivative 2 displays a doublet of doublets at d = À18.5 ppm ( 1 J SiP = 192.1 Hz, 2 J SiP = 60.1 Hz), thus indicating the presence of two phosphorus atoms in the molecule. Large silicon-phosphorus coupling constants have been observed for monophosphonium silaylides ( 1 J SiP = 141-157 Hz).…”

A Nitrido‐Centered Uranium Azido Cluster Obtained from a Uranium Azide

“…[16] These fascinating compounds were prepared by using a classic synthetic method which involves the two-electron reduction of azide to nitride and N 2 by a reducing metal complex. [2] However, for low-valent uranium this method appears very sensitive to the nature of the ancillary ligands and has in other cases resulted only in the isolation of stable uranium azido complexes, [17][18][19][20][21] including a structurally characterized binary heptaazido anion. [22] We have recently shown the versatility of the oxidation reactions of trivalent uranium iodide to produce highnuclearity clusters.…”