Increasing the Brønsted acidity of Ph2PO2H by the Lewis acid B(C6F5)3. Formation of an eight-membered boraphosphinate ring [Ph2POB(C6F5)2O]2

The Deutsche Forschungsgemeinschaft (DFG) is gratefully acknowledged for financial support. The theoretical part of this work was supported by the Russian Science Foundation (Project 14-13-00832).Autoprotolysis of the metastable acid (C6F5)3BOPPh2OH, prepared in situ by the reaction of the rather weak Brønsted acid Ph2PO2H with the strong Lewis acid B(C6F5)3, gave rise to the formation of the eight-membered ring [Ph2POB(C6F5)2O]2 and C6F5H. The conjugate base was isolated as stable sodium crown ether salt [Na(15-crown-5)][Ph2PO2B(C6F5)3].Publisher PDFPeer reviewe

Improving the efficiency of electric network equipment operational service

Maintenance and repair (M&R) of electric network equipment is one of the crucial methods for reliable power supplying. For implementing the condition based maintenance strategy is necessary to solve a number of problems, including prioritizing of preventive measures order and determining optimal time of their periodic. This paper points out two specific aspects: 1) development of an adequate reliability simulation model to optimize the operational factors of electric network equipment; 2) advantages of the proposed M&R optimization methodology in the operational process of real distribution system. Developed probabilistic mathematical model of M&R allows determining criteria for obtaining the optimal solution according to the results of numerical calculations procedures. Described mathematical model is based on the theory of controlled Markov processes. This mathematical method allows describing “ageing” systems. The main advantages of the model are the possibility of considering all random processes for described type of equipment and obtaining the analytical solutions for basic reliability and economical indexes. Based on this, the criterions and strategy for choosing an optimal time intervals of M&R procedures have been formed. Improving the efficiency of M&R of electrical equipment is considered on a real distribution network

Perfluorinated Trialkoxysilanol with Dramatically Increased Brønsted Acidity

The Brønsted acidity of the perfluorinated trialkoxysilanol {(F3C)3CO}3SiOH is more than 13 orders of magnitude higher than that of orthosilicic acid, Si(OH)4, and even more for most previously known silanols. It is easily deprotonated by simple amines and pyridines to give the conjugate silanolates [OSi{OC(CF3)3}3

Catecholase activity of Mannich-based dinuclear CuII complexes with theoretical modeling: New insight into the solvent role in the catalytic cycle

Four new dinuclear CuII complexes were synthesised from two Mannich-base ligands namely 2,6-bis[bis(2-methoxyethyl)aminomethyl]-4-chlorophenol (HL1) and 2-[bis(2-methoxyethyl)aminomethyl]-4-chlorophenol (HL2): [Cu2(L1)(OH)](ClO4)2CH3OH (1), [Cu2(L2)2](ClO4)2H2O (2), [Cu2(L2)2(NO3)2] (3) and [Cu2(L2)2(OAc)2] H2O (4) and well characterised. X-ray diffraction analysis of the complexes reveals a Cu Cu distance of 2.9183(13), 2.9604(6), 3.0278(4) and 3.0569(11) \uc5, respectively. In 1 the metal coordination geometry is intermediate between trigonal bipyramidal (TBP) and square pyramidal (SP) (t = 0.488), in 2 the geometry is TBP (0.828 and 0.639) and in 3 and 4 is SP (t = 0.188 and 0.083, respectively). Spectrophotometric investigations to evaluate the catecholase activity of complexes against 3,5-di-tert-butylcatechol (3,5-DTBC) and tetrachlorocatechol (TCC) in three different solvents (acetonitrile, methanol and DMSO) under completely aerobic conditions reveal that complexes 1\u20134 are able to oxidise 3,5-DTBC in all the solvents, while TCC can be oxidised only in acetonitrile (kcat = 0.0002\u20130.02 s1). Intensive DFT calculations prove an ionic pathway for 1\u20133 while a unique neutral catalytic cycle for 4

Ligand-Induced Intramolecular Redox Diversity in Titanium Complexes with Acenaphthene-1,2-diimine

A series of the chlorido and alkoxychlorido titanium complexes of the general formula (dpp-Bian)Ti(OiPr)nCl3–n, where dpp-Bian = 1,2-bis[(2,6-iPr2C6H3)imino]acenaphthene n = 0 (2), 1 (3), 2 (4), as well as (dpp-Bian)Ti(OiPr)2 (5) and (dpp-Bian)Ti(OiPr)Cl3 (3-Cl), were isolated and characterized using single-crystal X-ray diffraction analysis and spectroscopic studies combined with density functional theory (DFT) calculations. In the solid state, compounds 2–4 reveal a square–pyramidal geometry at the metal center supported with monoanionic dpp-Bian, whereas 3-Cl with a neutral diimine ligand and 5 bearing a dianionic enebisamide dpp-Bian show, respectively, an octahedral and tetrahedral coordination surrounding the metal ion. Paramagnetic complexes 2–4 exhibit electron paramagnetic resonance spectra in both toluene solution and solid state, confirming the transfer of spin density from the metal ion to the dpp-Bian ligand as the number of alkoxy groups increases. The increase in polarity of the Ti–N bonds in the row 2 3 4 contributes to enhanced stability of the metal complexes with respect to O-donor molecules. Thus, in tetrahydrofuran (THF), compounds 2 and 3 undergo reversible solvolysis, whereas complex 4 is stable. The charge and spin density distributions as well as molecular orbital energies in 2–4 were analyzed on the basis of DFT calculations which also provided information on the electronic transition energies, absorption band assignments, and thermodynamic parameters of the reactions between the complexes and THF

Increasing the Brønsted acidity of Ph₂PO₂H by the Lewis acid B(C₆F₅)₃. Formation of an eight-membered boraphosphinate ring [Ph₂POB(C₆F₅)₂O]₂

Autoprotolysis of the metastable acid (C6F5)3BOPPh2OH, prepared in situ by the reaction of the rather weak Brønsted acid Ph2PO2H with the strong Lewis acid B(C6F5)3, gave rise to the formation of the eight-membered ring [Ph2POB(C6F5)2O]2 and C6F5H. The conjugate base was isolated as stable sodium crown ether salt [Na(15-crown-5)][Ph2PO2B(C6F5)3].</p

Taking a snapshot of the triplet excited state of an OLED organometallic luminophore using X-rays

OLED technology beyond small or expensive devices requires light-emitters, luminophores, based on earth-abundant elements. Understanding and experimental verification of charge transfer in luminophores are needed for this development. An organometallic multicore Cu complex comprising Cu–C and Cu–P bonds represents an underexplored type of luminophore. To investigate the charge transfer and structural rearrangements in this material, we apply complementary pump-probe X-ray techniques: absorption, emission, and scattering including pump-probe measurements at the X-ray free-electron laser SwissFEL. We find that the excitation leads to charge movement from C- and P- coordinated Cu sites and from the phosphorus atoms to phenyl rings; the Cu core slightly rearranges with 0.05 Å increase of the shortest Cu–Cu distance. The use of a Cu cluster bonded to the ligands through C and P atoms is an efficient way to keep structural rigidity of luminophores. Obtained data can be used to verify computational methods for the development of luminophores.ISSN:2041-172