Weakening the N-H Bonds of NH Ligands: Triple Hydrogen-Atom Abstraction to Form a Chromium(V) Nitride.

Weakening and cleaving N-H bonds is crucial for improving molecular ammonia (NH) oxidation catalysts. We report the synthesis and H-atom-abstraction reaction of bis(ammonia)chromium porphyrin complexes Cr(TPP)(NH) and Cr(TMP)(NH) (TPP = 5,10,15,20-tetraphenyl--porphyrin and TMP = 5,10,15,20-tetramesityl--porphyrin) using bulky aryloxyl radicals. The triple H-atom-abstraction reaction results in the formation of Cr(por)(≡N), with the nitride derived from NH, as indicated by UV-vis and IR and single-crystal structural determination of Cr(TPP)(≡N).

Oxidation of Ammonia with Molecular Complexes.

Oxidation of ammonia by molecular complexes is a burgeoning area of research, with critical scientific challenges that must be addressed. A fundamental understanding of individual reaction steps is needed, particularly for cleavage of N-H bonds and formation of N-N bonds. This Perspective evaluates the challenges of designing molecular catalysts for oxidation of ammonia and highlights recent key contributions to realizing the goals of viable energy storage and retrieval based on the N-H bonds of ammonia in a carbon-free energy cycle.

Triple hydrogen atom abstraction from Mn-NH complexes results in cyclophosphazenium cations.

All hydrogen atoms of the NH3 in [Mn(depe)2(CO)(NH3)]+ are abstracted by 2,4,6-tri-tert-butylphenoxyl radical, resulting in the isolation of a rare cyclophosphazenium cation, [(Et2P(CH2)2PEt2)N]+, in 76% yield. An analogous reaction is observed for [Mn(dppe)2(CO)(NH3)]+. Computations suggest insertion of NHx into a Mn-P bond provides the thermodynamic driving force.

Catalytic Silylation of Dinitrogen by a Family of Triiron Complexes.

A series of triiron complexes supported by a tris(β-diketiminate)cyclophane ( ) catalyze the reduction of dinitrogen to tris(trimethylsilyl)amine using KC and MeSiCl. Employing FeBr affords 83 ± 7 equiv. NH /complex after protonolysis, which is a 50% yield based on reducing equivalents.

Chalcogen Impact on Covalency within Molecular [Cu(μ-E)] Clusters (E = O, S, Se): A Synthetic, Spectroscopic, and Computational Study.

Reaction of the tricopper(I)-dinitrogen tris(β-diketiminate) cyclophane, Cu(N)L, with O-atom-transfer reagents or elemental Se affords the oxido-bridged tricopper complex Cu(μ-O)L (2) or the corresponding Cu(μ-Se)L (4), respectively. For 2 and 4, incorporation of the bridging chalcogen donor was supported by electrospray ionization mass spectrometry and K-edge X-ray absorption spectroscopy (XAS) data. Cu L-edge X-ray absorption data quantify 49.

Redox Isomeric Surface Structures Are Preferred over Odd-Electron Pt.

The formation of metal-ligand coordination networks on surfaces that contain redox isomers is a topic of considerable interest and is important for bifunctional metallochemistry, including heterogeneous catalysis. Towards this end, a tetrazine with two electron withdrawing pyrimidinyl substituents was co-deposited with platinum metal on the Au(100) surface. In a 2:1 metal:ligand ratio, only half of the platinum is oxidized to the +2 oxidation state, with the remainder coordinating to the ligand without charge transfer, as Pt .

A Tricopper(I) Complex Competent for O Atom Transfer, C-H Bond Activation, and Multiple O Activation Steps.

Oxygenation of a tricopper(I) cyclophanate (1) affords reactive transients competent for C-H bond activation and O atom transfer to various substrates (including toluene, dihydroanthracene, and ethylmethylsulfide) based on H NMR, gas chromatography/mass spectrometry (MS), and electrospray ionization (ESI)/MS data. Low product yields (<1%) are determined for C-H activation substrates (e.g, toluene, ethylbenzene), which we attribute to competitive ligand oxidation.

Electron and Oxygen Atom Transfer Chemistry of Co(II) in a Proton Responsive, Redox Active Ligand Environment.

The bis-pyrazolato pyridine complex LCo(PEt) serves as a masked form of three-coordinate Co and shows diverse reactivity in its reaction with several potential outer sphere oxidants and oxygen atom transfer reagents. N-Methylmorpholine N-oxide (NMO) oxidizes coordinated PEt from LCo(PEt), but the final cobalt product is still divalent cobalt, in LCo(NMO). The thermodynamics of a variety of oxygen atom transfer reagents, including NMO, are calculated by density functional theory, to rank their oxidizing power.

Countercations and Solvent Influence CO Reduction to Oxalate by Chalcogen-Bridged Tricopper Cyclophanates.

One-electron reduction of CuEL (L = tris(β-diketiminate)cyclophane, and E = S, Se) affords [CuEL], which reacts with CO to yield exclusively CO (95% yield, TON = 24) and regenerate CuEL. Stopped-flow UV/visible data support an A→B mechanism under pseudo-first-order conditions ( k = 115(2) s), which is 10 larger than those for reported copper complexes. The k values are dependent on the countercation and solvent (e.

A Multifunctional Pincer Ligand for Cobalt-Promoted Oxidation by N O.

The divalent cobalt complex of the diprotic pincer ligand bis-pyrazolylpyridine, (H L)CoCl , is dehydrohalogenated twice by LiN(SiMe ) in the presence of PEt to give monomeric S=1/2 LCo(PEt ) (1), fully characterized in the solid-state and solution as a square pyramidal monomer with a long axial Co-P bond. This 17-electron species reacts in time of mixing with N O to form L Co (μ-OPEt ) (2)+3 OPEt , the former the first example of phosphine oxide bridging two transition metals. The same products are formed from O , and divalent cobalt persists even in the presence of excess oxidant.

Dehydrohalogenation of proton responsive complexes: versatile aggregation via pyrazolate pincer ligand arms.

The behavior of the complex (HL)CoCl, where HL is a bis-(pyrazol-3-yl)pyridine, towards Brønsted bases is studied, to evaluate peripheral NH deprotonation as a route to a dianionic pincer ligand on a d center. Deprotonation is found to also remove chloride from cobalt, and the decreased metal coordination number is then satisfied by bimolecular reaction of the newly formed peripheral deprotonated pyrazolate nitrogen, leading to Co units bridged by some of the pyrazolates, in the analogous species [Co(L)(LH)](L) and [Co(L)(HL)][Co(L)], but also occasionally by chloride retention, in LiCoLCl. Reacting LiCoLCl with tBuNC, yields monomeric LCo(tBuNC), shown to be a 17 valence electron species.

Exercise in Eating Disorders Treatment: Systematic Review and Proposal of Guidelines.

Introduction: Although exercise is an effective intervention for many psychological health issues, it has often been overlooked as a potential adjunct to eating disorder (ED) treatment. Thus, our objective was to summarize the literature by synthesizing themes identified in clinical studies and explicit guidelines or recommendations for the use or management of exercise in ED interventions into a proposed set of guidelines for the use of exercise in ED treatment.

Methods: A literature search in exercise science, health psychology, and the ED literature was conducted.

Two- and Three-Electron Oxidation of Single-Site Vanadium Centers at Surfaces by Ligand Design.

Rational, systematic tuning of single-site metal centers on surfaces offers a new approach to increase selectivity in heterogeneous catalysis reactions. Although such metal centers of uniform oxidation states have been achieved, the ability to control their oxidation states through the use of carefully designed ligands had not been shown. To this end, tetrazine ligands functionalized by two pyridinyl or pyrimidinyl substituents were deposited, along with vanadium metal, on the Au(100) surface.

A pilot study examining diagnostic differences among exercise and weight suppression in bulimia nervosa and binge eating disorder.

Objective: The objective of this study was to investigate diagnostic differences in weight suppression (e.g., the difference between one's current body weight and highest non-pregnancy adult body weight) and exercise among Bulimia Nervosa (BN) and Binge Eating Disorder (BED).

Multiplying the electron storage capacity of a bis-tetrazine pincer ligand.

An unexpected doubling in redox storage emerging from a new pincer ligand upon bis-ligation of iron(ii) is described. When tetrazine arms are present at the two ortho positions of pyridine, the resulting bis-tetrazinyl pyridine (btzp) pincer ligand displays a single one-electron reduction at ca. -0.

Transition metal chlorides are Lewis acids toward terminal chloride attached to late transition metals.

Two different neutral tridentate imine-donor pincer ligands interact with excess MCl2 (M = Co or Cu) to form compounds of the same stoichiometry, (LMCl2)2·MCl2, where the assembling force is the electron richness of the terminal chlorides on the LMCl2 unit. Finite aggregation occurs for M = Co, but for M = Cu, an infinite polymeric structure is adopted, all because MCl2 is bifunctional, which thus bridges multiple MCl units. The bis-pyrazolylpyridine ligand has two acidic NH protons, and both of these are involved in intramolecular hydrogen bonds.

Examination of muscularity and body fat depictions in magazines that target heterosexual and gay men.

Previous content analyses of magazine images have typically examined within genres but failed to include comparisons between publications intended for various populations. The purpose of this study was to examine depictions of muscularity and thinness of male images in several widely distributed magazines that target male audiences from a variety of genres. Twenty-three magazine titles with the highest circulation rates that targeted heterosexual men, gay men, and general audiences were selected for image analyses.

Eating disorder-specific health-related quality of life and exercise in college females.

Objective: Although eating disorder (ED) symptoms result in reduced quality of life (QOL), research is needed to examine variables that influence this relationship. The purpose of our study was to conceptually examine the relationship among ED-specific QOL, ED symptoms, and exercise behavior.

Method: Female university students (N = 387) completed ED-specific QOL, exercise behavior, ED symptoms, and exercise dependence symptoms measures.

The role of exercise dependence for the relationship between exercise behavior and eating pathology: mediator or moderator?

Our study examined the potential mediating or moderating effect of exercise dependence on the exercise-eating pathology relationship. Female university students (N = 330) completed Internet-based self-report measures of exercise behavior, exercise dependence, and eating pathology. Exercise dependence served as a mediator for the relationship between exercise and eating pathology.

Can exercise treat eating disorders?

Exercise is not a standard intervention for patients with eating disorders. In this article, six studies are reviewed that examined exercise interventions in populations with eating disorders. The key conclusion is that exercise may improve a range of biopsychosocial outcomes in patients with eating disorders, but more research is needed.