Stabilized borylenes (L BH:) with weakly π-accepting substituents L, such as phosphines, were previously believed to be unstable. In the current manuscript, we describe a series of complexes formally containing a phosphine-stabilized borylene or boryl anion. In contrast to common trivalent boron compounds, the boron-based ligands in this study act as electron-donating ligands. The reported iron hydride complexes exhibit a unique reactivity pattern, undergoing a reversible B-H reductive elimination concomitant with oxidation of the boron(I) center.
To gain molecular level insights into the properties of certain functions and units of extended oxides/hydroxides, suitable molecular model compounds are needed. As an attractive route to access such compounds the trapping of early intermediates during the hydrolysis of suitable precursor compounds with the aid of stabilizing ligands is conceivable, which was tested for the aluminum(III)/water system. Indeed, trisilanols proved suitable trapping reagents: their presence during the hydrolysis of Al(i) Bu2 H in dependence on the amount of water used allowed for the isolation of tri- and octanuclear aluminum hydroxide cluster complexes [Al3 (μ2 -OH)3 (THF)3 (PhSi(OSiPh2 O)3 )2 ] (1) and [Al8 (μ3 -OH)2 (μ2 -OH)10 (THF)3 (p-anisylSi(OSiPh2 O)3 )4 ] (2). 1 can be regarded as the Al(OH)3 cyclic trimer, where six protons have been replaced by silyl residues. While 2 features a unique [Al8 (μ3 -OH)2 (μ2 -OH)10 ](12+) core. In contrast to most other known aggregates of this type, 1 and 2 can be readily prepared at reasonable scales, dissolve in common solvents, and retain an intact framework even in the presence of excessive amounts of water. This finding paves the way to future research addressing the reactivity of the individual functional groups.
The wind turbine industry is growing at an incredible rate as numerous governments demand an increase in renewable energy generation capacity. The great multitude of turbines on windfarms throughout the world range from ones which are controlled mechanically with gears to ones which are controlled with power electronics and no gears. A drivetrain for a wind turbine which eliminates the problems of a mechanical gearbox and avoids the size and weight issues of directly-driven wind turbines is desired. A magnetic gear is proposed to reduce the size of the generator and achieve similar torque reduction provided by a mechanical gearbox, without the maintenance and breakdown issues. A magnetic gearbox, of the concentric planetary type will be studied for the high-torque, low-speed requirements of a wind turbine hub. Torque ripple is investigated across multiple models to determine acceptable torque transfer performance.
Magnetic gears have been proposed as a means of increasing torque density within electromechanical systems, while avoiding problems associated with traditional mechanical gears. While the idea behind magnetic gears goes back to early patents, their study and use in industry has been very limited to date. This study looks into variations of the concentric planetary magnetic gear which could lead to further use. It also investigates applying winding function theory (WFT) to aid in analysis of the gear. The new application of winding function theory is verified with the use of finite element analysis (FEA) as well as a prototype which has been fabricated.Index Terms-Finite element analysis (FEA), magnetic gears, permanent magnets, winding function theory.
Magnetic gears are a new and rapidly emerging technology. Compared to mechanical gears, they enjoy the advantage of having inherent overload capability. However, their torsional stiffness is much lower than mechanical gears, resulting in oscillations during transient changes in speed and load. Damper windings have been used in synchronous generators to suppress oscillations due to transients, and they are applied to the magnetic gear for the same purpose. It is believed that this is the first attempt to add a passive means of oscillation damping to the magnetic gear, whereas all other previous means have been active.Index Terms-Damper windings, finite element analysis (FEA), magnetic gears, permanent magnets (PMs).
To investigate the effect of X in ambiphilic compounds BiX(o-PPh2-C6H4)2, PBiP-X, on metallophilic Pt-Bi interactions in its PtCl2 complexes two new derivatives PBiP-Me and PBiP-C6F5 were synthesized. Reaction with dichloro(1,5-cyclooctadiene)platinum(II) led to the platinum(II) complexes [PtCl2(PBiP-Me)], 3, and [PtCl2(PBiP-C6F5)], 4, which together with the halide [PtCl2(PBiP-Cl)], 2, reported previously, establish a series of related PBiP-X complexes differing only in X. This could be complemented by accessing [PtCl2(PBiP-OTf)], 5, through the reaction of 2 with AgOTf. Analysis of the geometrical and electronic structures of these complexes revealed that in all cases the platinum(II) centers act as donors (through their filled d(z(2)) orbitals) to the bismuth(III) centers (possessing σ*(Bi-X)/6p acceptor orbitals). The strength of these interactions increases with increasing electron-withdrawing character of X, which supports the conceptual approach in constructing this new class of compounds.
Marine propulsion systems have become increasingly electromechanical in recent years. Proposed systems show increasing torque density in an effort to reduce volume and weight. A magnetic gear is proposed to reduce the size of the propulsion motor and achieve similar torque amplification provided by a mechanical gearbox, without the maintenance and breakdown issues. A magnetic gearbox, of the concentric planetary type, will be studied for the high-torque low-speed requirements of a marine propulsion system. Torque ripple is investigated across multiple models to determine acceptable torque transfer performance.
In metal-mediated O activation, nickel(II) compounds hardly play a role, but recently it has been shown that enzymes can use nickel(II) for O activation. Now a low-coordinate Lewis acidic nickel(II) complex has been synthesized that reacts with O to give a nickel(II) organoperoxide, as proposed for the enzymatic system. Its formation was studied further by UV/Vis absorption spectroscopy, leading to the observation of a short-lived intermediate that proved to be reactive in both oxygen atom transfer and hydrogen abstraction reactions, while the peroxide efficiently transfers O atoms. Both for the enzyme and for the functional model, the key to O activation is proposed to represent a concomitant electron shift from the substrate/co-ligand.
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