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We report the development of ureas as sterically undemanding pro-ligands for Pd catalysis. N-Arylureas outperform phosphine ligands for the Pd-catalyzed heteroannulation of N-tosyl-o-bromoanilines and 1,3-dienes, engaging diverse coupling partners for the preparation of 2-subsituted indolines, including sterically demanding substrates that have not previously been tolerated. Experimental and computational studies on model Pd-urea and Pd-ureate complexes are consistent with monodentate binding through the nonsubstituted nitrogen, which is uncommon for metal-ureate complexes.

We report velocity rotation events with amplitudes more than a few tens of kilometers per second observed by the Magnetospheric Multiscale mission. The events are detected in the outer magnetosphere near the magnetopause at approximately noon magnetic local time. When we examine one event, velocity and magnetic field variations are correlated. Accelerated electrons >100 eV are present. The azimuthal propagation direction is opposite to that of the background convection, implying that the structure and the background have different sources. The magnetic field variation can be approximately fitted to that of the line current. It is inferred that bundles of magnetic field lines with the same helicity propagate with the Alfvén velocity along the background magnetic field. One possible source is a flux transfer event. In addition, the variation in the solar wind dynamic pressure may also affect the velocity rotation. We have found 18 events during the first 2 years of Magnetospheric Multiscale operations. The derived properties are generally similar to those from the event study. For some events, we have identified a flux transfer event as a possible source. Again, the dynamic pressure variation may be the cause as well. The events reported resemble in some respects crewcuts and midday auroral brightening sequence, as measured by ground‐based optical instruments. Velocity rotation events are measured in the subsolar, outer magnetosphere with amplitudes more than a few tens of kilometers per secondAzimuthal directions of convective motion of structures are often opposite to those of background plasmasSome structures are inferred to be due to flux transfer events, although solar wind dynamic pressure variations may also be a cause

We investigate the agyrotropic nature of electron distribution functions and their substructure to illuminate electron dynamics in a previously reported electron diffusion region (EDR) event. In particular, agyrotropy is examined as a function of energy to reveal detailed finite Larmor radius effects for the first time. It is shown that the previously reported ∼66 eV agyrotropic “crescent” population that has been accelerated as a result of reconnection is evanescent in nature because it mixes with a denser, gyrotopic background. Meanwhile, accelerated agyrotropic populations at 250 and 500 eV are more prominent because the background plasma at those energies is more tenuous. Agyrotropy at 250 and 500 eV is also more persistent than at 66 eV because of finite Larmor radius effects; agyrotropy is observed 2.5 ion inertial lengths from the EDR at 500 eV, but only in close proximity to the EDR at 66 eV. We also observe linearly polarized electrostatic waves leading up to and within the EDR. They have wave normal angles near 90°, and their occurrence and intensity correlate with agyrotropy. Within the EDR, they modulate the flux of 500 eV electrons travelling along the current layer. The net electric field intensifies the reconnection current, resulting in a flow of energy from the fields into the plasma. The process of reconnection involves an explosive transfer of magnetic energy into particle energy. When energetic particles contact modern technology such as satellites, cell phones, or other electronic devices, they can cause random errors and failures. Exactly how particles are energized via reconnection, however, is still unknown. Fortunately, the Magnetospheric Multiscale mission is finally able to detect and analyze reconnection processes. One recent finding is that energized particles take on a crescent‐shaped configuration in the vicinity of reconnection and that this crescent shape is related to the energy conversion process. In our paper, we explain why the crescent shape has not been observed until now and inspect particle motions to determine what impact it has on energy conversion. When reconnection heats the plasma, the crescent shape forms from the cool, tenuous particles. As plasmas from different regions mix, dense, nonheated plasma obscures the crescent shape in our observations. The highest‐energy particle population created by reconnection, though, also contains features of the crescent shape that are more persistent but appear less dramatically in the data. We study agyrotropy and energy dissipation in an EDR event on the ion and electron inertial scalesAgyrotropy is observed 2.5 ion inertial lengths from the Xpoint at energies above the electron crescent populationAmplitude and occurrence of electrostatic, linearly polarized waves near fcecorrelate with increased agyrotropy in and around the EDR

We present Magnetospheric Multiscale observations of an electron-scale current sheet and electron outflow jet for asymmetric reconnection with guide field at the subsolar magnetopause. The electron jet observed within the reconnection region has an electron Mach number of 0.35 and is associated with electron agyrotropy. The jet is unstable to an electrostatic instability which generates intense waves with E?amplitudes reaching up to 300 mV m-1and potentials up to 20% of the electron thermal energy. We see evidence of interaction between the waves and the electron beam, leading to quick thermalization of the beam and stabilization of the instability. The wave phase speed is comparable to the ion thermal speed, suggesting that the instability is of Buneman type, and therefore introduces electron-ion drag and leads to braking of the electron flow. Our observations demonstrate that electrostatic turbulence plays an important role in the electron-scale physics of asymmetric reconnection. Electron outflow jet of asymmetric magnetic reconnection is observedElectron jet is unstable to Buneman-type instability generating intense electrostatic wavesThe instability leads to thermalization and braking of the electron jet

The electron drift instrument (EDI) on Cluster pioneered a new method of measuring electric fields, using a beam of electrons to sample the drift velocity over a km‐scale gyro orbit. The technique is especially well suited to measuring weak, sub‐mV/m, convection fields due to its sensitivity (to both components in the plane perpendicular to B) and because it is unaffected by the anomalous local electric fields that are generated by spacecraft‐plasma interactions. Because EDI requires exquisite beam pointing with active tracking of the firing directions, measurements are less regular, or even impossible, in rapidly varying electric and magnetic fields; however, in the many regimes where tracking is successful the resulting measurements are reliably accurate. We review the EDI technique and instrumentation, and present six areas of investigation using Cluster data: (1) Detailed comparisons of EDI data with the electric field and waves double probe measurements show excellent agreement in many cases but identify large discrepancies where strong ion outflow in the polar regions creates local spacecraft wake effects. (2) The wake effect is exploited to infer quantitative ion outflow rates. Detailed convection patterns in the (3) polar cap, (4) lobe, and (5) inner magnetosphere are derived under various driver conditions using statistical analyses of long term measurements during the Cluster mission. (6) EDI's large geometric‐factor detector is used for extremely high time resolution measurements of electrons at a specified energy and pitch angle. Complementarity of electron drift and double‐probe techniques establishedInner magnetosphere, polar cap, and tail‐lobe convection patterns determinedKey contribution to ion outflow velocities made Complementarity of electron drift and double‐probe techniques established Inner magnetosphere, polar cap, and tail‐lobe convection patterns determined Key contribution to ion outflow velocities made

A dipolarization of the background magnetic field was observed during a conjunction of the Magnetospheric Multiscale (MMS) spacecraft and Van Allen Probe B on September 22, 2018. The spacecraft were located in the inner magnetosphere at L∼ 6–7 just before midnight magnetic local time (MLT). The radial separation between MMS and Probe B was ∼1RE. Gradual dipolarization or an increase of the northward component BZof the background field occurred on a timescale of minutes. Exploration of energization and Radiation in Geospace located 0.5 MLT eastward at a similar Lshell also measured a gradual increase. The spatial scale was of the order of 1 RE. On top of that, MMS and Probe B measured BZincreases, and a decrease in one case, on a timescale of seconds, accompanied by large electric fields with amplitudes > several tens of mV/m. Spatial scale lengths were of the order of the ion inertial length and the ion gyroradius. The inertial term in the momentum equation and the Hall term in the generalized Ohm's law were sometimes non‐negligible. These small‐scale variations are discussed in terms of the ballooning/interchange instability and kinetic Alfvén waves among others. It is inferred that physics of multiple scales was involved in the dynamics of this dipolarization event. A dipolarization was observed during a conjunction of Magnetospheric Multiscale and Van Allen Probe B in the inner magnetosphereA BZincrease on a timescale of minutes was overlaid with those on a timescale of secondsThe inertial term and the Hall term sometimes played a role during BZincreases on a timescale of seconds A dipolarization was observed during a conjunction of Magnetospheric Multiscale and Van Allen Probe B in the inner magnetosphere A BZincrease on a timescale of minutes was overlaid with those on a timescale of seconds The inertial term and the Hall term sometimes played a role during BZincreases on a timescale of seconds