Dynamic, reversible oxidative addition of highly polar bonds to a transition metal

The combination of Pt0 complexes and indium trihalides leads to compounds that form equilibria in solution between their In-X oxidative addition (OA) products (PtII indyl complexes) and their metal-only Lewis pair (MOLP) isomers (LnPt→InX3). The position of the equilibria can be altered reversibly by changing the solvent, while the equilibria can be reversibly and irreversibly driven towards the MOLP products by addition of further donor ligands. The results mark the first observation of an equilibrium between MOLP and OA isomers, as well as the most polar bond ever observed to undergo reversible oxidative addition to a metal complex. In addition, we present the first structural characterization of MOLP and oxidative addition isomers of the same compound. The relative energies of the MOLP and OA isomers were calculated by DFT methods, and the possibility of solvent-mediated isomerization is discussed

Synthesis and Reactivity of a Dialane-Bridged Diradical

Radicals of the lightest group 13 element, boron, are well established and observed in numerous forms. In contrast to boron, radical chemistry involving the heavier group 13 elements (aluminum, gallium, indium, and thallium) remains exceedingly underexplored, primarily attributed to the formidable synthetic challenges associated with these elements. Herein, we report the synthesis and isolation of planar and twisted conformers of a doubly CAAC (cyclic alkyl(amino)carbene)-radical-substituted dialane. Extensive characterization through spectroscopic analyses and X-ray crystallography confirms their identity, while quantum chemical calculations support their open-shell nature and provide further insights into their electronic structures. The dialane-connected diradicals exhibit high susceptibility to oxidation, as evidenced by electrochemical measurements and reactions with o-chloranil and a variety of organic azides. This study opens a previously uncharted class of dialuminum systems to study, broadening the scope of diradical chemistry and its potential applications

Tetraiododiborane(4) (B2_2I4_4) is a Polymer based on sp3^3 Boron in the Solid State

Herein we present the first solid‐state structures of tetraiododiborane(4) (B$_2$I$_4$), which was long believed to exist in all phases as discrete molecules with planar, tricoordinate boron atoms, like the lighter tetrahalodiboranes(4) B$_2$F$_4$, B$_2$Cl$_4$, and B$_2$Br$_4$. Single‐crystal X‐ray diffraction, solid‐state NMR, and IR measurements indicate that B$_2$I$_4$ in fact exists as two different polymeric forms in the solid state, both of which feature boron atoms in tetrahedral environments. DFT calculations are used to simulate the IR spectra of the solution and solid‐state structures, and these are compared with the experimental spectra

Pastoralist Way of Life Under Threat: : Assessing the vulnerability risks faced by pastoralist communities as well as their potential to adapt to climate change in the Horn of Africa

The aim of the thesis was to examine the main causes of pastoral  vulnerability to climate change as well as assess their adaptive capacity to withstand future climate disturbances in the Horn of Africa. By studying two of the most iconic pastoralists’ communities in Africa – the Somali and the Massai’s in Kenya, the study intended to use the communities as representative to the overall pastoralist’s situation in the Horn of Africa. The study used the 2007 IPCC Vulnerability Assessment framework that entails exposure, sensitivity and adaptive capacity to climate change as a guiding instrument to comprehend the complexities of the pastoral livelihood. The participants of the study included pastoralists, officials from the government, NGO’s and research Institutions. Major findings of this study were, in addition to climate manifesting in destructive forms, pastoralism faces political marginalization, shrinking pastureland, sprawling urbanization, exponential growth of population and conflicts. Despite the challenges, the study also finds strong adaptive capacity by the pastoralists. Adaptation strategies include traditional methods of rangeland management and migration. The study also shows new modern methods adaptation to climate mainly instigated by the pastoralists with assistance from external actors, these methods include; Ecological Based Adaptation and technology driven approaches as well as a mixture of agriculture and pastoralism – agro-pastoralism. It was also found that the two communities studied face different climate challenges and adaptation approaches

Dibortetraiodid (B2_2I4_4) ist im Festkörper ein Polymer aus sp3‐hybridisiertem Bor

Anhand der ersten Festkörperstrukturen von Dibortetraiodid (B$_2$I$_4$) wird gezeigt, dass dieses nicht, wie lange angenommen, analog zu den leichteren Dibortetrahalogeniden B$_2$F$_4$, B$_2$Cl$_4$ und B$_2$Br$_4$ in allen Aggregatzuständen in Form diskreter Moleküle mit planaren, dreifach koordinierten Boratomen vorliegt. Röntgenstrukturanalysen, Festkörper‐NMR‐ und IR‐Messungen zeigen, dass B$_2$I$_4$ im Festkörper in zwei polymeren Konformeren vorkommt, die tetraedrisch koordinierte Boratome enthalten. Anhand von DFT‐Rechnungen werden die IR‐Spektren in Lösung und im Festkörper simuliert und mit den experimentellen Daten verglichen

Selection of backfill grout for shallow geothermal systems: Materials investigation and thermo-physical analysis

A main aspect of the geothermal well design is the selection of grouts backfilling the space between a geothermal probe and the surrounding ground, taking into consideration the mineralogical, thermo–physical, mechanical and flowability properties. The EU GEO4CIVHIC project aimed at developing efficient and cost-effective geothermal systems suitable for the air-conditioning refurbishment of urban buildings. A selection of different grouts was performed to ensure the whole efficiency of shallow geothermal heat exchangers designed within the project. Experimental tests were executed to identify flowable grouts with the best possible combination of different material properties, while also fulfilling a competitive cost target set forth in the preliminary project cost analysis. Grout acceptance criteria were defined: a working time of at least 4 h, a water bleeding target of 2% and a volumetric shrinkage upper bound of 4%, a thermal conductivity in water saturated conditions of at least 1.4 to 1.5 Wm−1K−1, a compressive strength range of 1 to 2.1 MPa, a flow time range of 60 ± 15 s. Two out of six commercial grouts were selected for installations onsite