Modeling Complex Ligands for High Oxidation State Catalysis: Titanium Hydroamination with Unsymmetrical Ligands.

A method for modeling high oxidation state catalysts is used on precatalysts with unsymmetrical and symmetrical bidentate ligands to get a more detailed understanding of how changes to ancillary ligands affect the hydroamination of alkynes catalyzed by titanium. To model the electronic donor ability, the ligand donor parameter (LDP) was used, and to model the steric effects, percent buried volume (% ) was employed. For the modeling study, 7 previously unpublished unsymmetrical Ti(XX')(NMe) precatalysts were prepared, where XX' is a chelating ligand with pyrrolyl/indolyl linkages.

Reactivity of [(PNP)Mn(CO)] with Organophosphates.

Organophosphorus nerve agents (OPAs) are a toxic class of synthetic compounds that cause adverse effects with many biological systems. Development of methods for environmental remediation and passivation has been ongoing for years. However, little progress has been made in therapeutic development for exposure victims.

Homoleptic Uranium-Bis(acyl)phosphide Complexes.

The first uranium bis(acyl)phosphide (BAP) complexes were synthesized from the reaction between sodium bis(mesitoyl)phosphide () or sodium bis(2,4,6-triisopropylbenzoyl)phosphide () and UI(1,4-dioxane). Thermally stable, homoleptic BAP complexes were characterized by single-crystal X-ray diffraction and electron paramagnetic resonance (EPR) spectroscopy, when appropriate, for the elucidation of the electronic structure and bonding of these complexes. EPR spectroscopy revealed that the BAP ligands on the uranium center retain a significant amount of electron density.

An Allyl Uranium(IV) Sandwich Complex: Are ϕ Bonding Interactions Possible?

A method to explore head-to-head ϕ back-bonding from uranium f-orbitals into allyl π* orbitals has been pursued. Anionic allyl groups were coordinated to uranium with tethered anilide ligands, then the products were investigated by using NMR spectroscopy, single-crystal XRD, and theoretical methods. The (allyl)silylanilide ligand, N-((dimethyl)prop-2-enylsilyl)-2,6-diisopropylaniline (LH), was used as either the fully protonated, singly deprotonated, or doubly deprotonated form, thereby highlighting the stability and versatility of the silylanilide motif.

Expanding the Nonaqueous Chemistry of Neptunium: Synthesis and Structural Characterization of [Np(NR)Cl], [Np(NR)Cl], and [Np{(R)(SiMeH)}(NR)] (R = SiMe).

Reaction of 3 equiv of NaNR (R = SiMe) with NpCl(DME) in THF afforded the Np(IV) silylamide complex, [Np(NR)Cl] (), in good yield. Reaction of with 1.5 equiv of KC in THF, in the presence of 1 equiv of dibenzo-18-crown-6, resulted in formation of [{K(DB-18-C-6)(THF)}(μ-Cl)][Np(NR)Cl] (), also in good yield.

Employing Lewis Acidity to Generate Bimetallic Lanthanide Complexes.

With the advent of lanthanide-based technologies, there is a clear need to advance the fundamental understanding of 4f-element chelation chemistry. Herein, we contribute to a growing body of lanthanide chelation chemistry and report the synthesis of bimetallic 4f-element complexes within an imine/hemiacetalate framework, [Ln = lanthanide; TPT = tris(pyridineimine)(Tren)tris(methoxyhemiacetalate); Tren = tris(2-aminoethylamine)]. These products are generated from hydrolysis and methanolysis of the cage ligand tris(pyridinediimine)bis(Tren) (; Tadanobu et al.

Synthesis and Characterization of a Neutral U(II) Arene Sandwich Complex.

Reduction of IU(NHAr) (Ar = 2,6-(2,4,6-PrCH)CH) results in a rare example of a U(II) complex, U(NHAr), and the first example that is a neutral species. Here, we show spectroscopic and magnetic studies that suggest a 5f6d valence electronic configuration for uranium, along with characterization of related U(III) complexes.

Quantifying ligand effects in high-oxidation-state metal catalysis.

Catalysis by high-valent metals such as titanium(IV) impacts our lives daily through reactions like olefin polymerization. In any catalysis, optimization involves a careful choice of not just the metal but also the ancillary ligands. Because these choices dramatically impact the electronic structure of the system and, in turn, catalyst performance, new tools for catalyst development are needed.

A complex with nitrogen single, double, and triple bonds to the same chromium atom: synthesis, structure, and reactivity.

A nitrogen-based analogue of the Schrock and Clark "yl-ene-yne" complex, W(CBu )(CHBu )(CHBu )(dmpe), has been prepared. The new complex is the nitrido, imido, amido anion [NCr(NPh)(NPr)], which was structurally characterized with the [K(crypt-2.2.