Interatomic Electron Transfer Research Articles

Contact-Electro-Catalysis Through Electret Behavior to Facilitate Electron Transfer.

Contact-electro-catalysis (CEC) usually uses polymer dielectrics as its catalysts under mechanical stimulation conditions, which although has a decent catalytic dye degradation effect still warrants performance improvement. A carrier separation promotion strategy based on an internal electric field by polarization can effectively improve ferroelectric material performance in photocatalysis and piezocatalysis. Therefore, carrier separation as a necessary process of CEC also can be promoted and is largely expected to improve CEC performance theoretically. However, the carrier separation enhancement by the internal electric field strategy has not been achieved in the CEC experiment yet, because of the difficulty of building an internal electric field in an inert polymer dielectric. Herein, a polytetrafluoroethylene (PTFE) dielectric was charged through an electret process, which was believed to establish an internal electric field for CEC catalysts proved by KPFM, XPS, and triboelectric nanogenerator voltage output analysis. The fastest degradation rate of methyl orange reached over 90% at 1.5 h, while the hydroxyl free radical (•OH) yield of the PTFE electret was nearly three times that of the original PTFE. Density functional theory (DFT) calculations verified that the potential barrier of interatomic electron transfer between PTFE and H2O was reduced by 37% under the internal electric field. The electret strategy used herein to optimize the PTFE catalyst provides a base for the use of other general plastics in CEC and facilitates the production of easily prepared, easily recyclable, and inexpensive polymer dielectric catalysts that can promote large-scale pollutant degradation via CEC.

Applicability of transferable multipole pseudo-atoms for restoring inner-crystal electronic force density fields. Chemical bonding and binding features in the crystal and dimer of 1,3-bis(2-hydroxyethyl)-6-methyluracil.

We considered it timely to test the applicability of transferable multipole pseudo-atoms for restoring inner-crystal electronic force density fields. The procedure was carried out on the crystal of 1,3-bis(2-hydroxyethyl)-6-methyluracil, and some derived properties of the scalar potential and vector force fields were compared with those obtained from the experimental multipole model and from the aspherical pseudo-atom model with parameters fitted to the calculated structure factors. The procedure was shown to accurately replicate the general vector-field behavior, the peculiarities of the quantum potentials and the characteristics of the force-field pseudoatoms, such as charge, shape and volume, as well as to reproduce the relative arrangement of atomic and pseudoatomic zero-flux surfaces along internuclear regions. It was found that, in addition to the quantum-topological atoms, the force-field pseudoatoms are spatially reproduced within a single structural fragment and similar environment. In addition, the classical and nonclassical hydrogen bonds in the uracil derivative crystal, as well as the H...O, N...O and N...C interactions in the free π-stacked dimer of the uracil derivative molecules, were studied using the potential and force fields within the concepts of interatomic charge transfer and electron lone pair donation-acceptance. Remarkably, the nitrogen atoms in the N...O and N...C interactions behave rather like a Lewis base and an electron contributor. At the same time, the hydrogen atom in the H...O interaction, being a Lewis acid, also participates in the interatomic electron transfer by acting as a contributor. Thus, it has been argued that, when describing polar interatomic interactions within orbital-free considerations, it makes more physical sense to identify electronegative (electron occupier) and electropositive (electron contributor) atoms or subatomic fragments rather than nucleophilic and electrophilic sites.

Curtailing the Excess eg-Orbital Filling of a Ni Atom by Enhanced Interatomic Charge Transfer within a Bimetallic 2D Metal–Organic Framework for the Oxygen Evolution Reaction

Electrochemical conversion technologies rely on the design and creation of highly efficient electrocatalysts. The oxygen evolution reaction (OER), which has applications in water splitting and metal–air batteries, is a crucial process in such conversions. Herein, a bimetallic Co, Ni-based ultrathin metal–organic framework nanoribbon (NiCo-NR) is reported for an efficient OER. It is proposed that in ultrathin MOF nanoribbons, the surface atoms (Co, Ni) are coordinatively unsaturated, due to which the interatomic electron transfer within the MOF makes more active adsorption sites on the surface. The catalyst exhibits an overpotential of 244 mV at a current density of 10 mA cm–2 with a Tafel slope value of 85 mV dec–1. For the stability experiment, the catalyst was exposed for 35 h of uninterrupted operation at a current density of 100 mA cm–2. Our findings showed that coordinatively unsaturated transition metal atoms were dominant active sites and the electrocatalytic activity can be tuned by the coupling interactions of Ni and Co metals. The excess eg-orbital filling of the Ni atom, which limits the electrocatalytic performance, can be reduced by π-donation from Ni to Co through the oxygen atom.

Electronic and energy level structural engineering of graphitic carbon nitride nanotubes with B and S co-doping for photocatalytic hydrogen evolution

The ideal photocatalyst used for photocatalytic water splitting requires strong light absorption, fast charge separation/transfer ability and abundant active sites. Heteroatom doping offers a promising and rational approach to optimize the photocatalytic activity. However, achieving high photocatalytic performance remains challenging if just relying on single-element doping. Herein, Boron (B) and sulfur (S) dopants are simultaneously introduced into graphitic carbon nitride (g-C3N4) nanotubes by supramolecular self­assembly strategy. The developed B and S co-doped g-C3N4 nanotubes (B,S-TCN) exhibited an outstanding photocatalytic performance in the conversion of H2O into H2 (9.321 mmol g−1h−1), and the corresponding external quantum efficiency (EQE) reached 5.3% under the irradiation of λ = 420 nm. It is well evidenced by the closely combined experimental and (density functional theory) DFT calculations: (1) the introduction of B dopants can facilitate H2O adsorption and drive interatomic electron transfer, leading to efficient water splitting reaction. (2) S dopants can stretch the VB position to promote the oxidation ability of g-C3N4, which can accelerate the consumption of holes and thus inhibit the recombination with electrons. (3) the simultaneous introduction of B and S can engineer the electronic and energy level structural of g-C3N4 for optimizing interior charge transfer. Finally, the purpose of maximizing photocatalytic performance is achieved.

Interatomic electron transfer promotes electroreduction CO2-to-CO efficiency over a CuZn diatomic site

Interatomic electron transfer promotes electroreduction CO2-to-CO efficiency over a CuZn diatomic site

Cu-N-bridged Fe-3d electron state regulations for boosted oxygen reduction in flexible battery and PEMFC

Rational design of hetero-diatomic catalysts (DACs) with tunable electronic structures is an effective approach to accelerate the sluggish kinetics of oxygen reduction reaction (ORR) in metal-air batteries and proton-exchange membrane fuel cells (PEMFCs), which, however, still remains a great challenge to date. Herein, we propose a novel multi-step collaborative synthesis strategy to fabricate the N-bridged Fe and Cu diatomic electrocatalysts (Fe, Cu DAs-NC). Benefitting from the inter-atomic electron transfer and robust graphitized structure, the optimized Fe, Cu DAs-NC catalyst exhibits significantly enhanced ORR performances in both alkaline and acidic media, featuring the half-wave potentials of 0.94 V and 0.80 V, respectively. The established solid-state flexible Zn-air battery and H2-O2 single fuel cell using Fe, Cu DAs-NC as cathode deliver an extra-high power density of 83 mW cm−2 and a maximum power output of 875 mW cm−2, respectively. In-situ Raman spectroscopy and density functional theory calculations reveal that the strong synergistic interactions between FeN4 and CuN4 moieties are responsible for the d-orbital shift of the atomic Fe and Cu sites and charge polarization between them in the N-bridged coordination environment, which results in the well-defined and favorable adsorption free energy regulations and consequent much enhanced catalytic activity of the diatomic catalysts.

The bonding of H in Zr under strain

Accurate computer simulation is important for understanding the role of irradiation-induced defects in zirconium alloys found in nuclear reactors. Of particular interest is the distribution and trapping of hydrogen, and the formation of zirconium hydride. These simulations require an accurate representation of Zr-H bonding in order to predict the behaviour of H around atomic-scale defects, dislocation lines, and dislocation loops. Here we explore the bonding of H in Zr under strain, how well it is represented by state-of-the-art Embedded Atom Method (EAM) potentials, and what physics is needed for an accurate representation in a Linear Combination of Atomic Orbitals (LCAO) Density Functional Theory (DFT) framework. For H in dilute solution under hydrostatic strain in the range -10% to +10%, solution energies and Zr-H bond lengths computed using EAM potentials are found to be in poor agreement with plane-wave DFT results. We note that the bond lengths are in a poor agreement even in equilibrium. LCAO basis sets are used to explore the importance of electron distribution around H atoms, and the transfer of electrons between H and Zr. The electron distribution around H atoms is found to be important to the explanation of the difference between octahedral and tetrahedral interstitial sites for H, with H in a tetrahedral site having very similar bonding to H in zirconium hydrides. The interatomic electron transfer has a smaller impact but is needed for maximum accuracy.

Influence of self-substitution on the thermoelectric Fe2VAl Heusler alloy

The microstructure and the thermoelectric properties were systematically determined in the Fe2V1+xAl1-x, Fe2+xVAl1-x, Fe2-xV1+xAl series to investigate the influence of self-substitution on the Fe2VAl Heusler alloy. In the explored range of compositions (−0.1 < x < 0.1), all these series are solid solutions, which form anti-site defects to accommodate the off stoichiometry. They all crystallize in the cubic L21 structure, but their lattice parameter unusually increases with x. A Bader analysis based on Density Functional Theory calculations indicates that these uncommon lattice parameter changes arise from variations in the interatomic electron transfer. The antisite defects behave like dopants that control the conduction type and charge carrier concentration. This leads to large thermoelectric power factor (PF) in the Fe2V1+xAl1-x series, which displays the largest electronic mobility. PF = 6.7 mW m−1 K−2 at 250 K and PF = 3.2 mW m−1 K−2 at 325 K are reached in n-type Fe2V1.03Al0.97 and p-type Fe2V0.985Al1.015 respectively. The lattice thermal conductivity systematically decreases upon self-substitution, but with differences among the series which can be traced back to the interatomic electron transfer unveiled by the Bader analysis. Finally, the figure of merit is improved to ZT = 0.06 at 500 K in p-type Fe2V0.93Al1.07 and ZT = 0.15 at 420 K in n-type Fe2V1.08Al0.92.

Relationship between interatomic electron transfer and photocatalytic activity of TiO2

We demonstrate the direct observation of interatomic electron excitation and transfer on single-crystal TiO2 (001) surface for water splitting by a synchronous illumination X-ray photoelectron spectroscopy (SI-XPS). The quantitative results clearly reveal that the initially absorbed water molecules on TiO2 surface promote the electron transfer between Ti and O atoms. However, when water molecule was dissociated into OH and H groups on Ti and O sites, respectively, the electron excitation and transfer ability have been gradually decreased and finally terminated, probably due to the reverse electron-attraction of OH group on Ti atoms. Amazingly, when Pt co-catalyst was deposited on TiO2, the electron excitation between Ti and O atoms have been significantly enhanced and no evident decrease has been observed during the entire water splitting process. In addition, the changes of Pt–O and Ti–O chemical bonds at the photocatalytic interfaces have been also detected. Furthermore, based on the above mechanism studies, the photocatalytic hydrogen production system for Pt/R-TiO2 (001) in KOH solution containing CH3OH was proposed, which exhibits a significant enhancement of hydrogen evolution rate (20.78 μmol h−1), which is nearly 2.5 times higher than that of traditional Pt/R-TiO2 (001) in CH3OH system (8.35 μmol h−1). The finding in this work may pave the way for developing other high-efficiency photocatalytic hydrogen production system over TiO2-based photocatalysts.

Photosystem II Acts as a Spin-Controlled Electron Gate during Oxygen Formation and Evolution.

The oxygen evolution complex (OEC) of photosystem II (PSII) is intrinsically more active than any synthetic alternative for the oxygen evolution reaction (OER). A crucial question to solve for the progress of artificial photosynthesis is to understand the influential interactions during water oxidation in PSII. We study the principles of interatomic electron transfer steps in OER, with emphasis on exchange interactions, revealing the influence of delocalizing ferromagnetic spin potentials during the catalytic process. The OEC is found to be an exchange coupled mixed-valence electron-spin acceptor where its orbital physics determine the unique activity of PSII. The two unpaired electrons needed in the triplet O2 molecule interact with the high spin state of the catalyst via exchange interactions; the optimal ferromagnetic catalyst and the resulting radical intermediates are spin paired. As a result, the active center of the CaMn4O5 cofactor, stimulated by the driving potential provided by photons, works as a spin valve to accelerate the formation and release of O2 from diamagnetic H2O.

Structural, electronic, and magnetic properties of vanadium atom-adsorbed MoSe2 monolayer**Project supported by the National Basic Research Program of China (Grant No. 2011CB606405), the CAEP Microsystem and THz Science and Technology Foundation, China (Grant No. CAEPMT201501), and the Science Challenge Project, China (Grant No. JCKY2016212A503).

Using the first-principles calculations, we study the structural, electronic, and magnetic properties of vanadium adsorbed MoSe2 monolayer, and the magnetic couplings between the V adatoms at different adsorption concentrations. The calculations show that the V atom is chemically adsorbed on the MoSe2 monolayer and prefers the location on the top of an Mo atom surrounded by three nearest-neighbor Se atoms. The interatomic electron transfer from the V to the nearestneighbor Se results in the polarized covalent bond with weak covalency, associated with the hybridizations of V with Se and Mo. The V adatom induces local impurity states in the middle of the band gap of pristine MoSe2, and the peak of density of states right below the Fermi energy is associated with the V-dz2 orbital. A single V adatom induces a magnetic moment of 5 μB that mainly distributes on the V-3d and Mo-4d orbitals. The V adatom is in high-spin state, and its local magnetic moment is associated with the mid-gap impurity states that are mainly from the V-3d orbitals. In addition, the crystal field squashes a part of the V-4s electrons into the V-3d orbitals, which enhances the local magnetic moment. The magnetic ground states at different adsorption concentrations are calculated by generalized gradient approximations (GGA) and GGA+U with enhanced electron localization. In addition, the exchange integrals between the nearest-neighbor V adatoms at different adsorption concentrations are calculated by fitting the first-principle total energies of ferromagnetic (FM) and antiferromagnetic (AFM) states to the Heisenberg model. The calculations with GGA show that there is a transition from ferromagnetic to antiferromagnetic ground state with increasing the distance between the V adatoms. We propose an exchange mechanism based on the on-site exchange on Mo and the hybridization between Mo and V, to explain the strong ferromagnetic coupling at a short distance between the V adatoms. However, the ferromagnetic exchange mechanism is sensitive to both the increased inter-adatom distance at low concentration and the enhanced electron localization by GGA+U, which leads to antiferromagnetic ground state, where the antiferromagnetic superexchange is dominant.

Two-dimensional layered chalcogenides: from rational synthesis to property control via orbital occupation and electron filling.

Electron occupation of orbitals in two-dimensional (2D) layered materials controls the magnitude and anisotropy of the interatomic electron transfer and exerts a key influence on the chemical bonding modes of 2D layered lattices. Therefore, their orbital occupations are believed to be responsible for massive variations of the physical and chemical properties from electrocatalysis and energy storage, to charge density waves, superconductivity, spin-orbit coupling, and valleytronics. Especially in nanoscale structures such as nanoribbons, nanoplates, and nanoflakes, 2D layered materials provide opportunities to exploit new quantum phenomena. In this Account, we report our recent progress in the rational design and chemical, electrochemical, and electrical modulations of the physical and chemical properties of layered nanomaterials via modification of the electron occupation in their electronic structures. Here, we start with the growth and fabrication of a group of layered chalcogenides with varied orbital occupation (from 4d/5d electron configuration to 5p/6p electron configuration). The growth techniques include bottom-up methods, such as vapor-liquid-solid growth and vapor-solid growth, and top-down methods, such as mechanical exfoliation with tape and AFM tip scanning. Next, we demonstrate the experimental strategies for the tuning of the chemical potential (orbital occupation tuned with electron filling) and the resulting modulation of the electronic states of layered materials, such as electric-double-layer gating, electrochemical intercalation, and chemical intercalation with molecule and zerovalence metal species. Since the properties of layered chalcogenides are normally dominated by the specific band structure around which the chemical potential is sitting, their desired electronic states and properties can be modulated in a large range, showing unique phenomena including quantum electronic transport and extraordinary optical transmittance. As the most important part of this Account, we further demonstrate some representative examples for the tuning of catalytic, optical, electronic, and spintronic properties of 2D layered chalcogenides, where one can see not only edge-state induced enhancement of catalysis, quantum Aharonov-Bohm interference of the topological surface states, intercalation modulated extraordinary transmittance, and surface plasmonics but also external gating induced superconductivity and spin-coupled valley photocurrent. Since our findings reflect the critical influences of the electron filling of orbital occupation to the properties in 2D layered chalcogenides, we thus last highlight the importance and the prospective of orbital occupation in 2D layered materials for further exploring potential functionalized applications.

Single-site tin-grafted anatase TiO2 for photocatalytic hydrogen production: Toward understanding the nature of interfacial molecular junctions formed in semiconducting composite photocatalysts

This work focuses on the nature of enhanced H2 production over SnO2/TiO2 composite photocatalysts. Three kinds of Sn-modified TiO2 materials were prepared by different methods. Photocatalytic H2 production from methanol/water solution as a model reaction was used to evaluate the photocatalytic properties of the materials. The chemical states of Sn were characterized in detail by transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray absorption fine structure spectroscopy. The results reveal a Sn nuclearity-dependent enhancement of H2 production over Sn/TiO2 photocatalysts. According to the characterization results, it was well established that the number of TiIV–O–SnIV linkages formed at the TiO2–SnO2 interface determines the enhancement amplitude of H2 production. The photogenerated electrons of TiO2 across the interfacial linkages are transferred into the mononuclear Sn moieties grafted on the (101) and (001) planes, where H2 is presumably released. An interatomic electron transfer pathway for accelerating photocatalytic H2 production over Sn/TiO2 catalysts was proposed based on this work.

Orbital reflectometry of oxide heterostructures

The occupation of d orbitals controls the magnitude and anisotropy of the inter-atomic electron transfer in transition-metal oxides and hence exerts a key influence on their chemical bonding and physical properties. Atomic-scale modulations of the orbital occupation at surfaces and interfaces are believed to be responsible for massive variations of the magnetic and transport properties, but could not thus far be probed in a quantitative manner. Here we show that it is possible to derive quantitative, spatially resolved orbital polarization profiles from soft-X-ray reflectivity data, without resorting to model calculations. We demonstrate that the method is sensitive enough to resolve differences of ~3% in the occupation of Ni e(g) orbitals in adjacent atomic layers of a LaNiO(3)-LaAlO(3) superlattice, in good agreement with ab initio electronic-structure calculations. The possibility to quantitatively correlate theory and experiment on the atomic scale opens up many new perspectives for orbital physics in transition-metal oxides.

Structural anomalies, spin transitions, and charge disproportionation in LnCoO3

The diamagnetic-paramagnetic and insulator-metal transitions in LnCoO3 perovskites (Ln=La,Y, rare earths) are reinterpreted and modeled as a two-level excitation process. In distinction to previous models, the present approach can be characterized as a low-high-intermediate spin LS-HS-IS scenario. The first level is the local excitation of HS Co3+ species in the LS ground state. The second excitation is based on the interatomic electron transfer between the LS/HS pairs, leading finally to a stabilization of the metallic phase based on IS Co3+. The model parameters have been quantified for Ln=La, Pr, and Nd samples using the powder neutron diffraction on the thermal expansion of Co–O bonds that is associated with the two successive spin transitions. The same model is applied to interpret the magnetic susceptibility of LaCoO3 and YCoO3.

Resonant inelastic x-ray scattering spectra for electrons in solids

conservation are discussed. At the opposite extreme are rare-earth systems (metals and oxides), in which the 4f electrons are almost localized with strong electron correlation. The observations are interpreted based on the effects of intra-atomic multiplet coupling and weak interatomic electron transfer, which are well described with an Anderson impurity model or a cluster model. In this context a narrowing of spectral width in the excitation spectrum, polarization dependence, and the magnetic circular dichroism in ferromagnetic materials are discussed. The authors then consider transition-metal compounds, materials with electron correlation strengths intermediate between semiconductors and rare-earth systems. In these interesting cases there is an interplay of intra-atomic and interatomic electronic interactions that leads to limitations of both the band model and the Anderson impurity model. Finally, other topics in resonant x-ray emission studies of solids are described briefly.

Atomic and electronic structure of crystalline and amorphous alloys. II. Strong electronic bonding effects in Ca-Al compounds.

Calculations of the atomic and electronic structure of ${\mathrm{Ca}}_{\mathrm{x}}$${\mathrm{Al}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$ glasses (with x=0.70, 0.60, 0.50, and 0.33) and of the crystalline intermetallic compound ${\mathrm{CaAl}}_{2}$ are presented. For the amorphous alloys the calculations are based on realistic models for the atomic structure constructed by a molecular-dynamics simulation linked to a steepest-descent potential-energy mapping. The effective interatomic forces are calculated using pseudopotential theory. We find that both the atomic and the electronic structures are dominated by strong electronic bonding effects: (a) The strong (s,p,d) hybridization of the free-electron-like conduction band of pure Al is broken up on alloying with Ca, and we find nearly separate Al 3s and Al 3p bands which are much narrower than the s and p bands in pure Al; (b) only the Al 3p states interact substantially with the Ca states. The interatomic electron transfer is small, but we find a substantial intra-atomic d-to-s transfer on the Al sites and an s-to-d transfer on the Ca sites. In the atomic structure the s-d promotion leads to a strong contraction of the Ca-Ca bonds in both the crystalline and the amorphous alloys compared to pure Ca, and a preferential Ca-Al bonding in the Al-rich but not in the Ca-rich alloys. The calculated electronic structure is well confirmed in all its details by heat-capacity, photoemission, and soft-x-ray emission spectra. The x-ray-diffraction data for the atomic structure corroborate the predicted compression of the Ca-Ca distances and the overall form of the correlation functions (which points to a local topology best described as a disordered tetrahedral close packing) but show distinctly lower and broader peaks. We argue that this is due to the short mean free path of the electrons, which will lead to a damping of the oscillations in the interatomic interactions.

Electron transfer and bonding in the transition metal diborides the heats of formation of the metal diborides derived from a theoretical bonding model

If interatomic electron transfer changes the bond orders from n o 1 , n o 2 , n o 3 …, to 1, n 2, n 3…, and z 1, z 2, z 3…, are the numbers of bonds of each type, the stability of a given compound is accounted for by the number of transfer electrons Δϵ = z 1( n o 1 − n 1) + z 2( n o 2 − n 2) + z 3( n o 3 − n 3)… occupying the lowest energy bands arising from the interaction of various atomic states. Δϵ is proportional to the heat of formation ΔH f . ΔH f = ΔϵE b where E b is the average energy for all valence bands. This approach is used to correlate the heats of formation of the transition metal diborides with Δϵ values obtained from electron population analyses. The consistency of the results lends support to the electron transfer bonding model and to the hypothesis that boron atoms in a metal diboride form a graphite-type layer structure after increasing their valence with the transfer electrons to a value of four. The delocalization of the transfer electrons between the π orbitals of boron and the empty d orbitals of the metal ensures electroneutrality and the stability of the metal diboride.

Ion-excitedKαx-ray satellite spectra of Si, S, Cl, and Ar in the gas phase

The $K\ensuremath{\alpha}$ satellite spectra of Si in the gases Si${\mathrm{H}}_{4}$ and Si${\mathrm{F}}_{4}$, of S in the gases ${\mathrm{H}}_{2}$S, S${\mathrm{O}}_{2}$, and S${\mathrm{F}}_{6}$, of Cl in the gases HCl and ${\mathrm{Cl}}_{2}$ and in the liquid C${\mathrm{Cl}}_{4}$, and of gaseous Ar produced by bombardment with oxygen ions were examined in detail and compared with the spectra of solid compounds obtained in a previous study. It was found that the apparent average state of $L$-shell ionization at the time of $K\ensuremath{\alpha}$ x-ray emission does not depend upon the physical state, but upon the availability of electrons from nearest-neighbor atoms. The $K\ensuremath{\alpha}$ satellite energies in conjunction with Hartree-Fock calculations provide a measure of the average numbers of missing $M$-shell electrons, and this information further supports the conclusion that interatomic electron transfer dominates the fast rearrangement occurring prior to $K\ensuremath{\alpha}$ x-ray emission in atoms having highly depleted $M$ shells. Various $K\ensuremath{\alpha}$ satellite peak-broadening mechanisms were considered and it was found that broadening due to the distribution of $M$-shell vacancies accounts for a significant portion of the total peak width.

Magnetic properties of N,N′-ethylenebis(salicylideneiminato) copper(II)

This paper reports the electron paramagnetic resonance spectra and magnetic susceptibility data on N,N′-ethylenebis(salicylideneiminato)copper(II). The results show that the ground state of the complex is of triplet multiplicity with the first excited state being a singlet, at 18·5 cm −1 higher in energy. EPR measurements confirm the existence of spin-spin coupling, and a value of D = 0·0365 cm −1 was obtained from the low-field parallel lines. The g value obtained from the triplet state spectra were g ∥ = 2·244, g ⊥ = 2·025, and 〈g〉 = 2·098. Cryomagnetic measurements for the low-temperature range 3·7–61°K in conjunction with a best fitting procedure yielded the magnetic parameters 2 J = +18·5 cm −1 and π = −2·15°K. A superexchange mechanism based on both intraatomic and interatomic electron transfer is proposed to account for the experimental data.