Lattice source for charge and spin inhomogeneity in 2D perovskite cuprates

This work is an attempt to show structural sources for the charge and spin inhomogeneity in 2D perovskite HTSC cuprates. In addition to an interest in the nature of the inhomogeneous stripe state with a large isotope effect, we highlight the structural features of cuprates (tilted CuO$_6$ octahedra with different orientation with respect to rock salt LaO layers), where sources of charge and spin inhomogeneity can be hidden. We used the Anderson model with the Jahn-Teller(JT) local cells, where it was shown in the Hartree Fock approximation the charge inhomogeneity arises at any low doping concentration $x$ and disappears when the doping level exceeds threshold concentration $x_c$, at which a nonzero JT displacement (tilting) separate CuO$_6$ octahedron becomes possible

VERIFICATION OF NUMERICAL SOLVING A PROBLEM OF PRESSURE LOSSES DETERMINATION OF FINITE WIDTH SLOT SINK

The results of numerical simulation of flow to slot sink is presented. Showing the course of research of solution depending on the size of the cells of the computational grid. Determined the combination of turbulence models and wall functions, the most adequate simulating the resistance of such flow.В работе представлены результаты численного моделирования течения к щелевому стоку. Показан ход исследования зависимости решения от размеров ячеек расчетной сетки. Определено сочетание моделей турбулентности и пристеночных функций, наиболее адекватно моделирующих сопротивление такого стока

Oxidation-induced C-H bond activation in iridium pincer complexes

Dehydrogenation reactions that produce molecular hydrogen are thermodynamically unfavourable. Desired is to couple them with a green driving force, such as oxidation with oxygen or an electric current. This, in turn, requires understanding of the catalyst's redox properties. Here we report oxidation of the iridium pincer complexes (POCOP)IrHCl (POCOP = 2,6-(tBu2PO)2C6H3; 1a) and (PCP)IrHCl (PCP = 2,6-(tBu2PCH2)2C6H3; 1c) that induced intramolecular C-H activation, followed by the formation of complexes with a cyclometallated tert-butyl group. Based on an electrochemical study and DFT calculations, we propose a mechanism that involves H+ loss from hydrochlorides 1a and 1c to give a highly reactive (pincer)IrCl+ compound

Iridium Pincer Complexes with an Olefin Backbone

Among the large variety of pincer complexes, those with carbon-carbon double bonds in the backbone have received little attention. Here, we report the reactions of complex (PC=CP)IrPh (3) and its derivatives with small molecules. Compound 3 readily adds CO to give the 18e adduct (PC=CP)IrPhCO (5a), which upon heating undergoes isomerization into the thermodynamically more stable isomer (PC=CP)IrCO(Ph) (5b), via reversible loss of CO. Reaction of 5 with hydrogen leads to the formation of saturated carbonyl compounds (PC-CP)IrCO (9) and (PC-CP)IrH(CO)H (10). In contrast to the hydrides (PC=-CP)IrH3 (6) and (PC CP)IrH4 (7), which are in tautomeric equilibrium via insertion of one of the hydrides into the olefin moiety, the former compounds do not isomerize into the olefin form. Protonation of 5 with CF3COOH gives a complex with an agostic methylene group, 11, which undergoes a rare transformation for Ir pincers, which is insertion of CO into the Ir Ph bond with subsequent formation of (PC=CP)IrOCOCF3 (12) and Ph-CHO. The trihydride 6 reacts with CO to give 9, which can add a second molecule of CO to reversibly form the dicarbonyl 13. Exposure of 6 to CO2 leads to the formate (PC-CP)Ir(H)0C(0)H (14). Complex 3 can take up a molecule of dioxygen to give peroxide (PC=CP)IrPhO, (8); a similar reaction is observed for the saturated complex 9, with formation of (PC-CP)Ir(CO)O-2 (15). XRD structures as well as reactivity point to a higher degree of O-O bond activation in 15

PC(sp(3))P pincer carbonyl complexes of iridium(I), and iridium(III)

The previously reported complex trans-[IrHCl{cis-1,3-bis-(di-tert-butylphosphino)methyl} cyclohexane] (2) forms the 18-electron carbonyl compound anti-[Ir(CO)HCl{cis-1,3-bis-((di-tert-butylphosphino)methyl)} cyclohexane] (5a)upon reaction with 1 atm CO. The structural isomer syn-[IrH(CO)Cl{cis-1,3-bis-((di-tert- butylphosphino)methyl)}cyclohexane] (5b)is obtained directly upon complexation of the ligand (1) with IrCl3 center dot H2O in refluxing DMF syn-5b is the first iridium aliphatic pincer complex with this orientation of the hydrogens and is the thermodynamically more stable isomer. Both compounds 5a and 5b afford the Ir(I)complex trans-[Ir(CO){cis-1,3-bis-((di-tert-butylphosphino)methyl)}cyclohexane] (4)upon treatment with KO'Bu. Complex 4 was also synthesised in a more straightforward fashion from the previously known terminal nitrogen complex trans-[Ir(N-2){cis-1,3-bis-((di-tert-butylphosphino)-methyl)} cyclohexane] (3)under atmospheric CO. The complexes 4, 5a and 5b were characterised spectroscopically and in the solid state. IR data point to a more electron rich metal centre as compared to the corresponding aromatic complexes

Iridium complexes with aliphatic, non-innocent pincer ligands

Pincer complexes attract considerable attention both as interesting objects for fundamental studies and efficient catalysts. This review describes a relatively new offshoot of the field - namely, the chemistry of iridium complexes with aliphatic PCsp3P non-innocent pincer ligands. High flexibility, often combined with possibility to activate internal C-H bonds, offers several new patterns of metal-ligand cooperation; some of them were successfully used in catalysis of acceptorless alcohol dehydrogenation, olefin hydroformylation and deuterium exchange, others opened up for remarkable stoichiometric reactions