Highly luminescent lanthanide complexes of 1-hydroxy-2-pyridinones.

The synthesis, X-ray structure, stability, and photophysical properties of several trivalent lanthanide complexes formed from two differing bis-bidentate ligands incorporating either alkyl or alkyl ether linkages and featuring the 1-hydroxy-2-pyridinone (1,2-HOPO) chelate group in complex with Eu(III), Sm(III), and Gd(III) are reported. The Eu(III) complexes are among some of the best examples, pairing highly efficient emission (Phi tot (Eu) approximately 21.5%) with high stability (pEu approximately 18.

Small molecule activation at uranium coordination complexes: control of reactivity via molecular architecture.

Electron-rich uranium coordination complexes display a pronounced reactivity toward small molecules. In this Feature article, the exciting chemistry of trivalent uranium ions coordinated to classic Werner-type ligand environments is reviewed. Three fundamentally important reactions of the [(((R)ArO)3tacn)U]-system are presented that result in alkane coordination, CO/CO2 activation, and nitrogen atom-transfer chemistry.

Carbon dioxide reduction and carbon monoxide activation employing a reactive uranium(III) complex.

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.

Dioxygen activation by a low-valent cobalt complex employing a flexible tripodal N-heterocyclic carbene ligand.

The novel versatile cobalt(I) tris-carbene complex [(TIMEN(xyl))Co]Cl (1) (where TIMEN = (tris[2-(3-arylimidazol-2-ylidene)ethyl]amine) reacts with CO, one-electron oxidizers such as CH(2)Cl(2), and O(2) to yield the cobalt complexes [(TIMEN(xyl))Co(CO)]Cl (2), [(TIMEN(xyl))Co(Cl)]Cl (3), and peroxo species [(TIMEN(xyl))Co(O(2))](BPh(4)) (5). All new complexes were fully characterized by (1)H NMR, UV/vis, and IR spectroscopy as well as superconducting quantum interference device (SQUID) magnetization measurements and single-crystal X-ray crystallography. The nucleophilic character of the eta(2)-bound dioxygen ligand in 5 was confirmed by density functional theory (DFT) studies and allows for oxygen-transfer reactions with electron-deficient organic substrates, such as benzoyl chloride.

Synthesis and characterization of electron-rich nickel tris-carbene complexes.

The synthesis and characterization of the first nickel(0)/(i) tris-carbene complex with a nitrogen anchored tripodal N-heterocyclic carbene ligand are described.

A linear, O-coordinated eta1-CO2 bound to uranium.

The electron-rich, six-coordinate tris-aryloxide uranium(III) complex [((AdArO)3tacn)U(III)] [where (AdArOH)3tacn = 1,4,7-tris(3-adamantyl-5-tert-butyl-2-hydroxybenzyl)1,4,7-triazacyclononane] reacts rapidly with CO2 to yield [((AdArO)3tacn)U(IV)(CO2)], a complex in which the CO(2) ligand is linearly coordinated to the metal through its oxygen atom (eta1-OCO). The latter complex has been crystallographically and spectroscopically characterized. The inequivalent O-C-O bond lengths [1.

Evidence for alkane coordination to an electron-rich uranium center.

A series of five uranium-alkane complexes of the general formula [(ArO)3tacn)U(alkane)].(cy-alkane) has been synthesized and crystallographically characterized. In all cases, X-ray diffraction studies revealed a pseudo-six-coordinate trivalent uranium core structure, [(ArO)3tacn)U], with a coordinated alkane ligand at the axial position.

Copper complexes of nitrogen-anchored tripodal N-heterocyclic carbene ligands.

Incorporation of a nitrogen functionality into a tripodal N-heterocyclic carbene ligand system affords the first N-anchored tetradentate tris-carbene ligands TIMEN(R) (R = Me (5a), t-Bu (5b), Bz (5c)). Treatment of the methyl derivatized [H(3)TIMEN(Me)](PF(6))(3) imidazolium salt (H(3)5a) with silver oxide yields the silver complex [(TIMEN(Me))(2)Ag(3)](PF(6))(3) (9), which, in a ligand transfer reaction, reacts with copper(I) bromide to give the trinuclear copper(I) complex [(TIMEN(Me))(2)Cu(3)](PF(6))(3) (10). Deprotonation of the tert-butyl and benzyl derivatives [H(3)TIMEN(t-Bu)](PF(6))(3) and [H(3)TIMEN(Bz)](PF(6))(3) yields the free tris-carbenes TIMEN(t-Bu) (5b) and TIMEN(Bz) (5c), which react readily with copper(I) salts to give mononuclear complexes [(TIMEN(t-Bu))Cu](PF(6)) (11b) and [(TIMEN(Bz))Cu]Br (11c).

Uranium tris-aryloxide derivatives supported by triazacyclononane: engendering a reactive uranium(III) center with a single pocket for reactivity.

The synthesis and spectroscopic characterization of the mononuclear uranium complex [((ArO)(3)tacn)U(III)(NCCH(3))] is reported. The uranium(III) complex reacts with organic azides to yield uranium(IV) azido as well as uranium(V) imido complexes, [((ArO)(3)tacn)U(IV)(N(3))] and [((ArO)(3)tacn)U(V)(NSi(CH(3))(3))]. Single-crystal X-ray diffraction, spectroscopic, and computational studies of this analogous series of uranium tris-aryloxide complexes supported by triazacyclononane are described.

Uranium complexes supported by an aryloxide functionalised triazacyclononane macrocycle: synthesis and characterisation of a six-coordinate U(III) species and insights into its reactivity.

A reactive low-valent uranium(III) complex supported by an aryloxide functionalised triazacyclononane has been synthesised and provides a platform for enhanced uranium reactivity.