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Benchmarking is a community-based and (preferably) community-driven activity involving consensus-based decisions on how to make reproducible, fair, and relevant assessments. In catalysis science, important catalyst performance metrics include activity, selectivity, and the deactivation profile, which enable comparisons between new and standard catalysts. Benchmarking also requires careful documentation, archiving, and sharing of methods and measurements, to ensure that the full value of research data can be realized. Beyond these goals, benchmarking presents unique opportunities to advance and accelerate understanding of complex reaction systems by combining and comparing experimental information from multiple, in situ and operando techniques with theoretical insights derived from calculations characterizing model systems. This Perspective describes the origins and uses of benchmarking and its applications in computational catalysis, heterogeneous catalysis, molecular catalysis, and electrocatalysis. It also discusses opportunities and challenges for future developments in these fields.

A single-step method for aniline formation was examined. Using a vanadate catalyst with an iron oxide co-catalyst and hydroxylamine hydrochloride as the amine source, an up to 90% yield of aniline was obtained with high selectivity. Further study showed that the overall reaction was pseudo-second order in terms of hydroxylamine concentration. Regioselective H-D exchange experiments suggest that the C-N bond formation step occurs via an irreversible electrophilic pathway. Based on all of the key observations, a mechanism is proposed. [ABSTRACT FROM AUTHOR]

Density functional calculations with the B3PW91 functional have been carried out on the TpRh(CNMe) species [Tp = HB[(pyrazolyl).sub.3]] as a model for Tp'Rh(CNC[H.sub.2]C[Me.sub.3]) [Tp' = HB[(3,5-dimethylpyrazolyl) .sub.3]] in interaction with propane. Two [sigma] complexes have been found as minima coordinated through either a methyl or a methylene C-H bond, the former being more stable. The approach of the alkane to TpRh(CNMe) has been studied. Although no transition state could be located, study of this path reveals the key importance of the partial decoordination of one pyrazole ring. The full coordination of the alkane can only be achieved when the metal is essentially in a square pyramid coordination with one of the three pyrazole groups only weakly interacting with Rh. The main reaction of the methyl [sigma] complex is oxidative addition, leading to the n-propyl hydride complex. In contrast, two reactions are found for the methylene Cr complex: (i) oxidative addition to give the isopropyl complex and (ii) exchange between the secondary and primary C-H bonds to convert the methylene complex of propane into a methyl complex of propane. This latter reaction has a much lower barrier than the oxidative addition at the methylene C-H bond. The results account well for most of the experimental results obtained from kinetic studies. Steric factors are found to control the energy barriers between these various processes, disfavoring any process that brings the central carbon into close proximity to Rh. density functional theory | hydrocarbon activation | rhodium | selectivity

The photochemical reaction of Tp'Rh(L)([[eta].sup.2]-PhN=L) [Tp' = tris-(3,5dimethyl pyrazolyl)borate, L = CNC[H.sub.2]C[Me.sub.3]] to form the coordinatively unsaturated reactive fragment, [Tp'Rh(L)], in the presence of alkylnitriles has been studied. The [Tp'Rh(L)] complex has been shown to selectively activate the primary C-H terminus of acetonitrile, propionitrile, butyronitrile, and valeronitrile. The resulting hydrides showed uncharacteristic stability in the presence of [C.sub.6] [D.sub.6] and their rates of reductive elimination were monitored by [sup.1]H NMR spectroscopy. Competition reactions permit the establishment of the relative stabilities of the activation products.

The zerovalent iron complex [Fe(P[Me.sub.3]).sub.2][(t-BuNC).sub.3] undergoes thermal cleavage of the C--N bond to give [Fe(P[Me.sub.3]).sub.2] [(t-BuNC).sub.2](H)(CN) and isobutylene. The reaction follows first order kinetics, and addition of the hydrogen-atom donor 1,4-cyclohexadiene leads to the preferential formation of isobutane rather than isobutylene. Mechanistic studies are consistent with a rate determining homolysis of the C--N bond, giving rise to tert-butyl radicals. Key words: iron, isocyanide, elimination, C--N cleavage. Le complexe ferrique zerovalent, [Fe(P[Me.sub.3]).sub.2] [(t-BuNC).sub.3], subit un clivage thermique de la liaison C--N et genere le [Fe(P[Me.sub.3]).sub.2][(t-BuNC).sub.2](H)(CN) et l'isobutylene. La reaction suit une cinetique du premier ordre, et l'addition du cyclohexadiene-1,4 comme source d'hydrogene mene a la formation preferentielle de l'isobutane plutot que l'isobutylene. Les modeles mecanistes sont conformes a l'homolyse cinetiquement determinante de la liaison C--N menant a la formation de radicaux de tert-butyl. Mots cles : fer, isocyanure, elimination, clivage de la liaison C--N.

Two continuous-wave (CW) focused C[O.sub.2] Doppler lidars (9.1 and 10.6 [[micro]meter]) were developed for airborne in situ aerosol backscatter measurements. The complex path of reliably calibrating these systems, with different signal processors, for accurate derivation of atmospheric backscatter coefficients is documented. Lidar calibration for absolute backscatter measurement for both lidars is based on range response over the lidar sample volume, not solely at focus. Both lidars were calibrated with a new technique using well-characterized aerosols as radiometric standard targets and related to conventional hard-target calibration. A digital signal processor (DSP), a surface acoustic wave spectrum analyzer, and manually tuned spectrum analyzer signal analyzers were used. The DSP signals were analyzed with an innovative method of correcting for systematic noise fluctuation; the noise statistics exhibit the chi-square distribution predicted by theory. System parametric studies and detailed calibration improved the accuracy of conversion from the measured signal-to-noise ratio to absolute backscatter. The minimum backscatter sensitivity is [approximately]3 x [10.sup.-12][m.sup.-1][sr.sup.-1] at 9.1 [[micro]meter] and [approximately]9 x [10.sup.-12][m.sup.-1][sr.sup.-1] at 10.6 [[micro]meter]. Sample measurements are shown for a flight over the remote Pacific Ocean in 1990 as part of the NASA Global Backscatter Experiment (GLOBE) survey missions, the first time to our knowledge that 9.1-10.6-[[micro]meter] lidar intercomparisons were made. Measurements at 9.1 [[micro]meter], a potential wavelength for space-based lidar remote-sensing applications, are to our knowledge the first based on the rare isotope 12C 18[O.sub.2] gas.

A new switched reluctance starter/generator (SR S/G) system has been developed for an aircraft engine application. The system is rated at 30 kW, 270 Vdc, 52 k r/min maximum operating speed. The system also provides 17 hp to start the 1 400-hp engine. The system consists of an SR machine directly coupled to the gas turbine engine, an inverter converter unit (ICU), and an electronic controller. The system is designed to meet requirements such as power quality per MIL-STD-704E, 30% (9 kW) step loads, 75% constant power loads, operation over a wide speed range, and a -51 [degrees] C to +125 [degrees] C environment. This paper focuses on the design and implementation of the system. The SR S/G system is currently undergoing design assurance tests. Test results are given to validate the system design and performance. System efficiency is about 80% when generating 30 kW.

Several kinetic techniques are employed to analyze the different thermodynamic trends that are observed during the carbon-hydrogen bond activation in different nitriles and chloroalkanes. The M-C bonds are shown to be highly strengthened by the presence of different CN and CL substitutents.

Research has been conducted on diallylanilines. The authors demonstrate that these compounds have undergone cobalt-carbonyl catalyzed rearrangement to quinolines.