Reactivity of a trans-[H-Mo≣Mo-H] Unit Towards Alkenes and Alkynes. Bimetallic Migratory Insertion, H-Elimination and Other Reactions

Complex [Mo2(H)2{μ-HC(NDipp)2}2(THF)2], (1·THF), reacts with C2H4 and PhCH[double bond, length as m-dash]CH2 to afford hydrido-hydrocarbyl and bis(hydrocarbyl) derivatives of the Mo[quadruple bond, length as m-dash]Mo bond. Reversible migratory insertion and β-hydrogen elimination, as well as reductive elimination and other reactions, have been uncovered. PhC[triple bond, length as m-dash]CH behaves instead as a Brönsted–Lowry acid towards the strongly basic Mo–H bonds of 1·THF.Ministerio de Economía y Competitividad CTQ2016-75193-PEuropean Research Council 75657

The Sustainable Management of Metals: An Analysis of Global Research

The objective of this study was to analyze research trends in the field of sustainable management of metals on a global level between 1993 and 2017. To do so, a bibliometric analysis was carried out on a total of 6967 articles. The results revealed the growing interest in this research field, particularly over the last five year-period during which 63% of all articles were published. The three journals in which most articles had been published were the Journal of Cleaner Production, ACS Sustainable Chemistry and Engineering, and Chemsuschem. The countries that published the most articles were China, the United States, India, Germany, and the United Kingdom. A sizeable network of collaboration has been established between countries for the joint publication of studies. The main lines of research have been focused on metal decontamination in water and soil, waste management oriented towards reuse and recycling, and the innovation of processes for cleaner and more efficient production. The results revealed the need for comprehensive studies that integrate different disciplines within the same analytical framework, and to promote research that contributes to the different dimensions of sustainability (environmental, economic, and social)

Evaluation of physichochemical parameters influencing bulking episodes in a municipal wastewater treatment plant

A study of physicochemical parameters in a municipal wastewater treatment plant was undertaken to consider the presence of bulking phenomena by means of statistical and logistic regression analyses. There appears to be an important effect on activated sludge settleability that can be related to the temperature of wastewater. Besides, there were significant differences between the percentage of nitrogen removal from the secondary treatment with the season. The SVI increased with conductivity, meanwhile BOD5 removal decreased with this parameter. The development of logistic regression models identified two statistically significant variables that appeared to be important to the contribution of a higher SVI: season and pH

Dynamic Kinetic Resolution of Hetero biaryl Ketones by Zinc- Catalyzed Asymmetr ic Hydrosil ylation

Adiastereo- and highly enantioselective dynamic kinetic resolution (DKR) of configurationally labile hetero- biaryl ketones is described. The DKR proceeds by zinc- catalyze dhydrosilylation of the carbonyl group ,thus leading to secondary alcohols bearing axial and central chirality .The strategy relies on the labilization of the stereogenic axis that takes place thanks to aLewis acid–base interaction between anitrogen atom in the heterocycle and the ketone carbonyl group .The synthetic utility of the methodology is demonstrated through stereospecific transformations into either N,N-ligands or appealing axially chiral, bifunctional thiourea organocata- lysts.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P, CTQ2016-76908-C2-2-P, contract RYC-2013-12585)European FEDER FundsJunta de Andalucía (Grant 2012/FQM 10787)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement n 8 8 291780

Boryl-assisted hydrogenolysis of a nickel–methyl bond

A stable Nickel(II) methyl complex containing a diphosphinoboryl (PBP) pincer ligand is described. Mechanistic studies on the hydrogenolysis of the Ni-Me bond suggest a metal ligand cooperation mechanism that involves the intermediacy of a - B‒H Ni(0) species that further undergoes B‒H oxidative addition to form a Ni(II) hydride complex

Efecto de la isquemia reperfusión hepatica en las membranas biológicas

Una de las causas más importantes de lesión hepática en situaciones como el trasplante hepático, la cirugía de resección hepática y los estados de shock es el fenómeno de isquemia-reperfusión. En la fase temprana de la reperfusión ocurren cambios en la microvascularización que implican la muerte de los hepatocitos, tras lo cual diversas células, como los polimofronucleares o los propios hepatocitos, liberan factores quimiotácticos e inflamatorios que perpetúan la lesión. Uno de los hechos más destacables de todo el proceso es la producción de radicales libres del oxígeno por parte del sistema xantina-oxidasa (XO) y las mitocondrias, estimulada principalmente por la depleción de adenosín trifosfato (ATP) celular en la fase hipóxica. Los radicales libres alteran la función y la estructura de las células hepáticas por medio del proceso de peroxidación lipídica, cuyo resultado es la disminución de la fluidez de la membrana celular y la consiguiente lesión irreversible del hígado. Nuestro objetivo fue valorar los niveles de fluidez en membranas celulares y mitocondriales de tres grupos de 4 ratas: 1) Controles sin isquemia; 2) 15 minutos de isquemia; 3) Isquemia seguida de 30 minutos de reperfusión vascular. La isquemia hepática se realizó por oclusión temporal de los dos elementos vasculares del pedículo hepático: arteria hepática y vena porta. La fluidez se determinó por espectroscopio de fluorescencia utilizando el 1-(4- trimetilamoniofenil) 6-fenil-1,3,5- hexatrieno- p- tolueno sulfonato (TMA-DPH) como marcador. Nuestros resultados demuestran que la fluidez disminuyó tanto en las membranas celulares como mitocondriales, si bien los cambios solo fueron significativos en las membranas celulares. Dado que la reperfusión de un órgano causa exacerbación del estrés oxidativo y que la exposición a radicales libres produce rigidez en las membranas biológicas, nuestros datos apoyan la hipótesis de que las alteraciones funcionales de las membranas celulares pueden desempeñar un papel clave en la lesión producida durante los fenómenos de isquemia reperfusión

Formation of C−X Bonds Through Stable Low-Electron Count Cationic Pt(IV) Alkyl Complexes Stabilized by N-Heterocyclic Carbenes

Cationic five-coordinate Pt(IV) alkyl complexes stabilized by bulky N-heterocyclic carbenes have been isolated and fully characterized. Related species have been postulated as key intermediates in carbon–heteroatom coupling reactions and most particularly in Shilov-type chemistry. The alkyl groups exhibit a pronounced electrophilic character and can undergo nucleophilic addition of pyridine, bromide, or iodide to form new carbon–heteroatom bonds. Nevertheless, direct reductive coupling to form C–X bonds can be operative in the absence of an external nucleophile source.Ministerio de Ciencia, Innovación y Universidades CTQ2013-45011Junta de Andalucía FQM-212

A Diels–Alder Reaction Triggered by a [4 + 3] Metallacycloaddition

The TpMe2Ir(III) complex 1-OH2 (TpMe2 = hydrotris(3,5-dimethylpyrazolyl)borate), which contains a labile molecule of water and an iridium-bonded alkenyl moiety (−C(R)═C(R)–(R=CO2Me)) as part of a benzo-annulated five-membered iridacycle, reacts readily with the conjugated dienes butadiene and 2,3-dimethylbutadiene to afford the corresponding Diels–Alder products. Experimental and DFT studies are in accordance with an initial [4 + 3] cyclometalation reaction between the diene and the five-coordinated 16-electron organometallic fragment 1 (generated from 1-OH2 by facile water dissociation). The reaction can be extended to a related TpIr(III) complex (Tp = hydrotris(pyrazolyl)borate) that also features a labile ligand (i.e., 2-THF).Ministerio de Economía y Competitividad CTQ2014- 51912-REDCJunta de Andalucía FQM-119, P09-FQM-483

Electrophilic activation of alkynes promoted by a cationic alkylidene complex of Pt(II)

Pt(II) alkylidene 1a has been reacted with terminal alkynes to afford ylide complexes 3a-d, resulting from electrophilic activation of the C≡C bond and its insertion into the platinacyclic fragment of 1a that contains the carbene functionality. DFT calculations indicate that the observed regioselectivity is determined by the nucleophilic attack of the alkyne to the alkylidene carbon.MICINN/AEI/10.13039/501100011033/, “ERDF A way of making Europe” (CTQ2017-82893-C2-2-R), MICINN (CTQ2016-75193-P and PID2019-110856GA-I00), US/FEDER/JUNTA, UE (US126226), and Junta de Andalucía (P18-FR-4688