Low-valent homobimetallic Rh complexes: influence of ligands on the structure and the intramolecular reactivity of Rh–H intermediates

Supporting two metal binding sites by a tailored polydentate trop-based (trop - 5H-dibenzo[a,d] cyclohepten-5-yl) ligand yields highly unsymmetric homobimetallic rhodium(I) complexes. Their reaction with hydrogen rapidly forms Rh hydrides that undergo an intramolecular semihydrogenation of two C≡C bonds of the trop ligand. This reaction is chemoselective and converts C≡C bonds to a bridging carbene and an olefinic ligand in the first and the second semihydrogenation steps, respectively. Stabilization by a bridging diphosphine ligand allows characterization of a Rh hydride species by advanced NMR techniques and may provide insight into possible elementary steps of H₂ activation by interfacial sites of heterogeneous Rh/C catalysts

To formalize or not to formalize: women entrepreneurs’ sensemaking of business registration in the context of Nepal

Despite the depiction of decisions to formalize informal firms as rational and ethical, many entrepreneurs in developing countries continue to operate informally regardless of its perceived illicit status. While existing research on why entrepreneurs choose informality emphasizes the economic costs and benefits of such decisions, this often overlooks the realities of the informal economy and the constraints which marginal populations—particularly women—face. In this paper, we use institutional theory and sensemaking to understand the experiences of women in the informal economy and what formalization means to them. We use a qualitative approach to collect data from 90 women entrepreneurs in three different cities in Nepal. In our findings, we identify three groups of women with distinctive understandings of formalization—business sustainability, livelihood sufficiency and strategic alignment. Their interpretation of formalization reveals the complex, dynamic, and cyclical nature of formalization decisions. Decisions are also guided by the optimization of social and emotional logics, whereby formalization is conceived differently depending on different life stages, experiences within the informal economy and wider socio-cultural contexts. Our findings highlight the ethical implications of formalization where being a ‘good citizen’, rather than complying with formal rules and regulations, is about attuning to and fitting in with socially prescribed roles. Our research provides a nuanced view of formalization decisions, challenging idealized and ethical notions of formalization as a desired end state

Increased Performance of an all-Organic Redox Flow Battery model by Nitration of the [4]Helicenium Ion Electrolyte

Redox Flow Batteries (RFBs) through their scalable design and virtually unlimited capacity, are promising candidates for large-scale energy storage. While recent advances in the development of redox-active bipolar organic molecules satisfy the prerequisites for the pioneering Symmetrical all-Organic Redox Flow Batteries (SORFBs) emerging, problems of low durability or low energy density remain a bottleneck for their wide-spread application. The present work reports that nitration of the [4]helicenium ion core (DMQA+) result in a significant enhancement of the electrochemical performance of DMQA as electrolyte for SORFBs. The physical and kinetic properties of NO2C+ were evaluated by cyclic voltammetry (CV) and UV-visible spectroscopy in acetonitrile and compared to those of its precursor HC+. The electrons storage ability of NO2C+ was investigated in three differents type of static H-cell experiments. In the first experiment, NO2C+ provided an open circuit voltage (OCV) of 2.24 V and demonstrated good stability, as well as high coulombic (>98%) efficiencies, over more than 200 charge/discharge cycles. In the second experiment, a charge-discharge cycling over the entire redox window of NO2C+ (OCV > 3 V) resulted in 80 cycles at a potential energy density above 12 Wh/L. During the last epxeriment, a bipolarization stress-test was performed during which NO2C+ demonstrated a remarkable durability of 90 cycles at 100% load with a perfect retention of capacity and coulombic efficiency. The electrochemical performance results of this enhanced redox material highlights that DMQA+ ions are robust and versatile materials for the emergence of symmetrical all-Organic ORF

Dis-assembly of a Benzylic CF₃ Group Mediated by a Niobium(III) Imido Complex

All three C–F bonds in CF₃-substituted arenes are activated by a niobium imido complex, driven by the formation of strong Nb–F bonds. The mechanism of this transformation was studied by NMR spectroscopy, which revealed the involvement of Nb­(III). Attempts to extend this chemistry to nonaromatic CF₃ groups led to intramolecular reactivity

Dis-assembly of a Benzylic CF₃ Group Mediated by a Niobium(III) Imido Complex

All three C–F bonds in CF₃-substituted arenes are activated by a niobium imido complex, driven by the formation of strong Nb–F bonds. The mechanism of this transformation was studied by NMR spectroscopy, which revealed the involvement of Nb­(III). Attempts to extend this chemistry to nonaromatic CF₃ groups led to intramolecular reactivity

A low-valent dinuclear ruthenium diazadiene complex catalyzes the oxidation of dihydrogen and reversible hydrogenation of quinones

The dinuclear ruthenium complex [Ru2H(mu-H)(Me(2)dad)(dbcot)(2)] contains a 1,4-dimethyl-diazabuta-1,3-diene (Me(2)dad) as a non-innocent bridging ligand between the metal centers to give a [Ru-2(Me(2)dad)] core. In addition, each ruthenium is bound to one dibenzo[a,e]cyclooctatetraene (dbcot) ligand. This Ru dimer converts H-2 to protons and electrons. It also catalyzes reversibly under mild conditions the selective hydrogenation of vitamins K-2 and K-3 to their corresponding hydroquinone equivalents without affecting the C=C double bonds. Mechanistic studies suggest that the [Ru-2(Me(2)dad)] moiety, like hydrogenases, reacts with H-2 and releases electrons and protons stepwise.Swiss National Science Foundation; ETH Zurich; China Scholarship Council; ETH Zurich Postdoctoral Fellowship Program - ETH Zurich-Marie Curie action for people [FEL-14 15-1]Open access articleThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Zero-valent amino-olefin cobalt complexes as catalysts for oxygen atom transfer reactions from nitrous oxide

The synthesis and characterization of several zero-valent cobalt complexes with a bis(olefin)-amino ligand is presented. Some of these complexes proved to be efficient catalysts for the selective oxidation of secondary and allylic phosphanes, as well as diphosphanes, even with a direct P-P bond. With 5 mol % catalyst loadings the oxidations proceed under mild conditions (25-70 °C, 7-22 h, 2 bar N O) and afford good to excellent yields (65-98 %). In this process, the greenhouse gas N O is catalytically converted into benign N and added-value organophosphorus compounds, some of which are difficult to obtain otherwise

Electron localization in a mixed-valence diniobium benzene complex

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