Explore the vast range of titles available.

The uranyl ion (UO 2 2+ ; U( vi ) oxidation state) is the most common form of uranium found in terrestrial and aquatic environments and is a central component in nuclear fuel processing and waste remediation efforts. Uranyl capture from either seawater or nuclear waste has been well studied and typically relies on extremely strong chelating/binding affinities to UO 2 2+ using chelating polymers 1 , 2 , porous inorganic 3 – 5 or carbon-based 6 , 7 materials, as well as homogeneous 8 compounds. By contrast, the controlled release of uranyl after capture is less established and can be difficult, expensive or destructive to the initial material 2 , 9 . Here we show how harnessing the redox-switchable chelating and donating properties of an ortho -substituted closo -carborane (1,2-(Ph 2 PO) 2 -1,2-C 2 B 10 H 10 ) cluster molecule can lead to the controlled chemical or electrochemical capture and release of UO 2 2+ in monophasic (organic) or biphasic (organic/aqueous) model solvent systems. This is achieved by taking advantage of the increase in the ligand bite angle when the closo -carborane is reduced to the nido -carborane, resulting in C–C bond rupture and cage opening. The use of electrochemical methods for uranyl capture and release may complement existing sorbent and processing systems. Redox-switchable chelation is demonstrated for a carborane cluster molecule, leading to controlled chemical or electrochemical capture and release of uranyl in monophasic or biphasic model solvent systems.

Here we describe the synthesis of two imido analogs of the uranyl ion, UO²⁺₂, in which the oxygens are replaced by divalent alkyl or aryl nitrogen groups: U(N[superscript t]Bu)₂I₂(THF)₂ (1) and U(NPh)₂I₂(THF)₃ (2) (where [superscript t]Bu is tert-butyl and THF is tetrahydrofuran). Both compounds have been fully characterized by standard analytical techniques, including x-ray crystallography, and the chemical bonding between the metal center and the nitrogen ligands was quantified by using hybrid density functional theory calculations. As expected for a uranyl analog, these complexes exhibit linear N-U-N linkages and very short U-N bonds. In addition, the theoretical calculations show strong involvement of the 5f and 6d electrons in the U-N bonding.

A complex featuring a uranium( VI ) terminal nitride functional group has been isolated through mild oxidation, and shown to be highly reactive. Under photolysis, it converts into a compound that is capable of C–H bond activation.

The monomeric trinitrosyl complex, W(NO) 3 Cl 3 , can be prepared by the treatment of WCl 6 in CH 2 Cl 2 with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmn2 1 as a three-component twin (a = 10.4280(4) Å, b = 6.3289(2) Å, c = 5.6854(2) Å, Z = 2, R 1 = 0.065, wR 2 = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W—N linkages are 1.88(2) and 1.92(1) Å long, while the two corresponding N—O bond lengths are 1.13(2) and 1.16(2) Å. DFT calculations on fac-W(NO) 3 Cl 3 at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO) 3 Cl 3 in CH 2 Cl 2 lose ClNO under ambient conditions and deposit the well-known [W(NO) 2 Cl 2 ] n polymer, and this conversion is fully reversible.Key words: nitrosyl, tungsten, structure, bonding.

This chapter describes advancements in organometallic actinide chemistry from 2006 to 2015. This cut‐off was chosen because (1) 10 years is a pleasingly round number and (2) 2006 is the publication year of the Chemistry of the Actinides and Transactinide Elements, 3rd edition. In order to get an overview of the scope of actinide organometallic and coordination chemistry, it explores the Cambridge Structural Database (CSD). The chapter also discusses aspects of covalency, and highlights experimental and computational techniques at the forefront of its evaluation. Chemists must be careful to make the distinction between energy‐driven covalency and the more traditional overlap‐driven covalency; experimental and theoretical studies show that for actinide‐ligand bonds. Both types of covalency may be operative for different classes of complexes depending on the oxidation state and nature of the ligand. In the past 10 years, considerable progress has been made in the synthesis of actinide complexes with group 16 donor ligands.

The monomeric trinitrosyl complex, W(NO) 3 Cl 3 , can be prepared by the treatment of WCl 6 in CH 2 Cl 2 with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmn2 1 as a three-component twin (a = 10.4280(4) Å, b = 6.3289(2) Å, c = 5.6854(2) Å, Z = 2, R 1 = 0.065, wR 2 = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W—N linkages are 1.88(2) and 1.92(1) Å long, while the two corresponding N—O bond lengths are 1.13(2) and 1.16(2) Å. DFT calculations on fac-W(NO) 3 Cl 3 at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO) 3 Cl 3 in CH 2 Cl 2 lose ClNO under ambient conditions and deposit the well-known [W(NO) 2 Cl 2 ] n polymer, and this conversion is fully reversible.Key words: nitrosyl, tungsten, structure, bonding.

The monomeric trinitrosyl complex, W(NO)^sub 3^Cl^sub 3^, can be prepared by the treatment of WCl^sub 6^ in CH^sub 2^Cl^sub 2^ with NO gas, and its identity has been unambiguously confirmed by a single-crystal X-ray diffraction analysis. The complex crystallizes in the space group Pmw2^sub 1^ as a three-component twin (a = 10.4280(4) [Angstrom], b = 6.3289(2) [Angstrom], c = 5.6854(2) [Angstrom], Z = 2, R^sub 1^ = 0.065, wR^sub 2^ = 0.176). Its solid-state molecular structure consists of a tungsten centre bound to three chloride ligands and three linear nitrosyl ligands in a fac-octahedral stereochemistry. In addition, the structure contains a crystallographically imposed mirror plane. The two independent W-N linkages are 1.88(2) and 1.92(1) [Angstrom] long, while the two corresponding N-O bond lengths are 1.13(2) and 1.16(2) [Angstrom]. DFT calculations on fac-W(NO)^sub 3^Cl^sub 3^ at the B3LYP/LANL2DZ level of theory afford optimized intramolecular metrical parameters that match the X-ray crystallographically determined bond lengths and bond angles quite well. In addition, they provide a rationale for the nearly linear W-N-O linkages extant in the complex. Solutions of fac-W(NO)^sub 3^Cl^sub 3^ in CH^sub 2^Cl^sub 2^ lose ClNO under ambient conditions and deposit the well-known [W(NO)^sub 2^Cl^sub 2^]^sub n^ polymer, and this conversion is fully reversible. [PUBLICATION ABSTRACT] Key words: nitrosyl, tungsten, structure, bonding.