The hydrogenated aluminium trimer: a theoretical examination of the formation and interconversion pathways

Five doublet isomers of the Al₃H₂ cluster lying within a narrow range of 5 kcal/mol, along with the isomerization transition states connecting them, have been located with the coupled-cluster CCSD(T) and DFT methods. The two most stable doublet structures, the C_2v planar including the two Hs bound terminally and C₁ non-planar showing one H in terminal site and the other in threefold site are found to be essentially degenerate. Although the reaction of Al₃ with H₂ to yield Al₃H₂ is found to be significantly exothermic, by 23.5 kcal/mol, this hydrogenation is impeded by a considerable kinetic barrier of 16 kcal/mol. Our result is consistent with the observed lack of reactivity of Al_n towards H₂(D₂) for n=3 under thermal conditions [3]. The quartet Al₃H₂ isomers are predicted to lie 16–21 kcal/mol higher in energy than the doublet analogues. Further dimerization of Al₃H₂ to form Al₆H₄ has also been examined. Electronic supplementary material Supplementary Online Material     

High-pressure hydrogenated fullerenes: Optical spectra and stability of C<Subscript>60</Subscript>H<Subscript>36</Subscript> at high pressure

The optical Raman and photoluminescence (PL) spectra of the high-pressure hydrogenated fullerene C₆₀ are studied at normal conditions and at high pressure. The Raman spectrum of the most stable hydrofullerene C₆₀H₃₆ contains a large number of peaks related to various isomers of this molecule. Comparison of the experimental data with the results of calculations shows that the most abundant isomers have the symmetries S₆, T, and D_3d. The Raman spectrum of deuterofullerene C₆₀H₃₆ is similar to that of C₆₀H₃₆, but the frequencies of the C-H stretching and bending modes are shifted due to the isotopic effect. The PL spectrum of hydrofullerene C₆₀H₃₆ is shifted to higher energies by approximately 1 eV with respect to that of pristine C₆₀. The effect of hydrostatic pressure on the Raman and PL spectra of C₆₀H₃₆ has been investigated up to 12 GPa. The pressure dependence of the phonon frequencies exhibits peculiarities at approximately 0.6 and 6 GPa. The changes observed at approximately 0.6 GPa are probably related to a phase transition from the initial orientationally disordered body-centered cubic structure to an orientationally ordered structure. The peculiarity at approximately 6 GPa may be related to a pressure-driven enhancement of the C-H interaction between the hydrogen and carbon atoms belonging to neighboring molecular cages. The pressure-induced shift of the photoluminescence spectrum of C₆₀H₃₆ is very small up to 6 GPa, and a negative pressure shift was observed at higher pressure. All the observed pressure effects are reversible with pressure.     

Isomeric C60F36(g) species: Computed structures and heats of formation

The recently measured heat of formation ΔH _f ^o of C₆₀F₃₆(g) is submitted for extensive computational treatment. The computations are performed at the AM1, PM3 and SAM1 semiempirical quantum-chemical levels on a set of selected isomers, especially those of T, C ₃, and D _3d symmetries. The SAM1 method produces somewhat lower values than PM3 and, in particular, AM1 (as is the case for pristine fullerenes). For example, the SAM1 computed value for the T isomer is ?1293 kcal/mol; i.e., it is within the experimental error. However, the issue of isomerism should also be taken into consideration accordingly and related kinetic aspects should be checked using computations. Even without these two additional steps being carried out, the agreement between the observed and computed values is encouraging.     

Interaction of Ga<Subscript>3</Subscript> cluster with molecular hydrogen: combined DFT and CCSD(T) theoretical study

We have explored the lowest doublet and quartet potential energy surfaces (PES) for the reaction of gallium trimer with H₂. This reaction was studied experimentally by Margrave and co-workers in a noble gas matrix. The detailed reaction paths ending up with the low-energy Ga₃H₂ hydride isomers have been predicted based on the high level ab initio coupled-cluster calculations (CCSD(T)) with large basis set. We have found that the reaction occuring on the lowest doublet PES is described by the activation barrier for H₂ cleavage of about 15 kcal/mol, consistent with experiment. In the most stable Ga₃H₂ hydride structure, whose formation is exothermic by 15 kcal/mol, both H atoms assume three-fold bridged positions. The diterminal planar structure of Ga₃H₂, proposed experimentally from the observed IR spectra, is found to be only 1 kcal/mol less stable than the dibridged form.     

Computational study of singlet and triplet sulfonylnitrenes insertion into the C―C or C―H bonds of ethylene

Formation of N‐sulfonylaziridines, N‐ethylidenesulfonamides, N‐vinylsulfonamides and 4,5‐dihydro‐1,2,3‐oxathiazole 2‐oxides by the reaction of singlet and triplet trifluoromethyl‐, methyl‐ and tosylnitrenes with ethylene is studied computationally at the B3LYP/6‐311++G(d,p) level of theory in both gas phase and in solution. Singlet sulfonylnitrenes react with ethylene via [1 + 2]‐cycloaddition exothermically to give N‐sulfonylaziridines. Triplet sulfonylnitrenes are formed from the singlet ones by the intersystem crossing with the energy barrier not exceeding 2.5 kcal/mol and react in a stepwise fashion by C‐addition or H‐abstraction. The C‐addition gives rise to the formation of N‐sulfonylaziridines or N‐ethylidenesulfonamides depending on the S―N―C_sp3―C_sp2 dihedral angle, with the barrier to rotation about the N―C_sp3 bond not exceeding 2.5 kcal/mol. The H‐abstraction results in N‐vinylsulfonamides. Transformation of N‐sulfonylaziridines to N‐ethylidenesulfonamides requires to overcome the barrier of 57–60 kcal/mol, N‐ethylidenesulfonamides to 4,5‐dihydro‐1,2,3‐oxathiazole 2‐oxides—74–80 kcal/mol and N‐vinylsulfonamides to N‐ethylidenesulfonamides—about 64 kcal/mol. The use of the polarizable continuum model does not lead to a change of the course of the reaction of trifluoromethanesulfonylnitrene with ethylene and only slightly affects the relative energies of the products, intermediates and transition states. Copyright © 2014 John Wiley & Sons, Ltd.     

Theoretical studies on [2 + 2 + 2] reaction mechanisms of three ethynes. More accurate estimation of activation energy

The mechanisms of the [2 + 2 + 2] cycloaddition reaction of three ethyne molecules were studied by ab initio molecular orbital and density functional methods. The transition states range from that of the concerted mechanism with D_3h symmetry to that of the stepwise mechanism with C₂ symmetry. The transition state structure and the activation energy depend on the basis set and computational method employed in the analysis. The activation energy barrier was determined to be in the range of 36–44 kcal/mol. The activation energy determined by various methods corresponds to the interaction energy, which is related to the electron correlation energy. The best estimation of the activation energy barrier is 41.6 kcal/mol, achieved from the relation between the interaction energy and the activation energy. Copyright © 2013 John Wiley & Sons, Ltd.     

A new allotropic form of carbon [C<Subscript>28</Subscript>]<Subscript>n</Subscript> based on fullerene C<Subscript>20</Subscript> and cubic cluster C<Subscript>8</Subscript> and Si and Ge analogs of this form: Computer simulation

The structure of a new allotropic form of carbon [C₂₈]_n having a simple cubic lattice and space group \(Pm \bar 3\) is proposed. The geometrical parameters of the building block of such a hypothetic crystal are preliminarily determined from DFT-PBE calculations of the cluster C₈@(C₂₀)₈ and the polyhedral hydrocarbon molecule C₈@(C₂₀H₁₃)₈, in which the centers of the cubic clusters C₈ coincide with the centers of the cluster C₈@(C₂₀)₈ and of the molecule C₈@(C₂₀H₁₃)₈, respectively, and dodecahedral C₂₀ carbon cages are located at the vertices of a cube. The energy of dissociation of the cluster C₈@(C₂₀)₈ into a cubic cluster C₈ and eight dodecahedral clusters C₂₀ is calculated to be 1482 kcal/mol, and the energy of each C₈-C₂₀ bond is equal to 74.2 kcal/mol. The structure of the [C₂₈]_n crystal is refined using the DFT-PBE96/FLAPW method and optimized geometry. Calculations show that the crystal is a dielectric with an energy gap of 3.3 eV. The lattice parameter a of the crystal is equal to 5.6 Å, and its density is 3.0 g/cm³. The possible existence of analogous allotropic forms of elements Si and Ge is discussed. A method is proposed for designing a hypothetic allotropic form [C₂₈]_n from C₂₀(CH₃)₈ molecules with T _h symmetry.     

Rate of abstraction of hydrogen atoms from ethane by muonium

Thermal reaction rates for the gas-phase reaction Mu+C₂H₆MuH+C₂H₅ have been measured bySR over the temperature range 510–730 K. The usual Arrhenius expression,k=Aexp(–E _a /RT), fits the data well, giving parametersA=1.0×10^–9 cm³ molecule^–1 s^–1 andE _a =15.35 kcal/mol. The activation energyE _a is 5.5 kcal/mol higher than for the H atom variant of this reaction, indicating a marked difference in reaction dynamics. Preliminary analysis indicates a still greater difference between Mu and H for the corresponding CH₄ reaction.     

Chemical reactivity of lithium‐doped fullerenes

The addition of free radicals and the 1,3 dipolar cycloaddition onto pristine and lithium‐doped C₆₀ were studied by means of the Perdew–Burke–Ernzerhof (PBE) and M06‐2X density functionals. In all cases, lithium increased the reactivity even though for the 1,3 dipolar cycloaddition onto C₆₀ the change observed with respect to bare C₆₀ was minimal. Both functionals employed gave similar encapsulation energies for Li@C₆₀ namely, 33.1 and 38.2 kcal/mol at the PBE/6‐31G* and M06‐2X/6‐31G*, respectively. However, the increased reactivity because of lithium doping determined at the PBE level is smaller as compared with that computed with the M06‐2X functional, whereas that determined at the second‐order Møller–Plesset (MP2) level is the largest one. For example, using the M06‐2X functional the binding energy of fluorine to Li@C₆₀ is 28.5 kcal/mol larger than that determined for C₆₀, whereas at the PBE/6‐31G* level it is predicted to be increased by 24.7 kcal/mol. The results clearly suggest that Li@C₆₀ is a much better free radical scavenger than C₆₀. Finally, the complex hindered rotations of lithium inside C₆₀ are expected to be strongly inhibited because lithium doping increases the well depth between the cage center and the equilibrium position near the addition site of the lithium atom. Copyright © 2011 John Wiley & Sons, Ltd.     

Effects of subsurface Na,H and C on the bonding of carbon to nickel surfaces

This paper reports the results of a theoretical study of Na, H and C subsurface atomic species in nickel and demonstrates how these interstitial atoms influence the reactivity of the Ni(111) surface and the structure of carbon species adsorbed on the surface. The benzene molecule, C₆H₆, in planar and nonplanar geometries, is used to probe bonding at the surface. Adsorption energies are calculated by ab initio configuration interaction techniques modelling the surface as an embedded cluster. Adsorption energies of planar C₆H₆ at the most stable, three-fold, adsorption site are 18 kcal/mol for the Ni(111) surface, and 10, 19 and 44 kcal/mol in the presence of the Na, H and C interstitials, respectively. The energies required for the planar to puckered distortion are 99 kcal/mol on Ni(111), 69 kcal/mol with the Na interstitial, 83 kcal/mol with H, and 134 kcal/mol with C compared to 198 kcal/mol for distortion of C₆H₆ in the gas phase. The possible relevance of these results to the nucleation of diamond on nickel are discussed. The results indicate that subsurface Na stabilizes tetrahedrally bonded carbon subunits of the diamond structure while subsurface C may make it easier for the overlayer to revert to a planar graphite structure.     

On the heat of formation of nitromethane

Two experimental values (?19.3 ± 0.3 and ?17.8 ± 0.1 kcal/mol) for the gas phase heat of formation (δ_fH) (298k) of nitromethane have been reported. Although these values differ by only 1.5 kcal/mol, substantially greater differences in theoretical and experimental results occur when these differing values are used to calculate thermodynamic properties. This is especially evident when these two values for the δ_fH of nitromethane are used to calculate thermodynamic properties of polynitro compounds. For example, when density functional theory (DFT) is coupled with the use of isodesmic reactions, the Δ_fH of octanitrocubane is calculated to be 160.6 or 172.6 kcal/mol, depending on which value is used. It should also be appreciated that several computational theories depend upon having access to reliable experimental data for testing and development. We have examined this discrepancy using several computational models and several levels of theory. Our results coupled with a comprehensive review of the literature support the lower (?19.3 ± 0.3 kcal/mol) experimental value. This is problematic because the higher value (?17.8 ± 0.1 kcal/mol) has been used in the development and/or testing of several semiempirical quantum mechanical models as well as ab initio Gaussian theory (G2 and G3). Copyright © 2008 John Wiley & Sons, Ltd.     

Hydrogen storage in Li-doped fullerene-intercalated hexagonal boron nitrogen layers

New materials for hydrogen storage of Li-doped fullerene (C₂₀, C₂₈, C₃₆, C₅₀, C₆₀, C₇₀)-intercalated hexagonal boron nitrogen (h-BN) frameworks were designed by using density functional theory (DFT) calculations. First-principles molecular dynamics (MD) simulations showed that the structures of the C _n -BN (n = 20, 28, 36, 50, 60, and 70) frameworks were stable at room temperature. The interlayer distance of the h-BN layers was expanded to 9.96–13.59 Å by the intercalated fullerenes. The hydrogen storage capacities of these three-dimensional (3D) frameworks were studied using grand canonical Monte Carlo (GCMC) simulations. The GCMC results revealed that at 77 K and 100 bar (10 MPa), the C₅₀-BN framework exhibited the highest gravimetric hydrogen uptake of 6.86 wt% and volumetric hydrogen uptake of 58.01 g/L. Thus, the hydrogen uptake of the Li-doped C _n -intercalated h-BN frameworks was nearly double that of the non-doped framework at room temperature. Furthermore, the isosteric heats of adsorption were in the range of 10–21 kJ/mol, values that are suitable for adsorbing/desorbing the hydrogen molecules at room temperature. At 193 K (–80 °C) and 100 bar for the Li-doped C₅₀-BN framework, the gravimetric and volumetric uptakes of H₂ reached 3.72 wt% and 30.08 g/L, respectively.     

A theoretical study of hydrogen adsorption on Li, Be, Na, and Mg atoms attached to aromatic hydrocarbons

The binding energy of a hydrogen molecule on metal atoms (Li, Be, Na, and Mg) attached to aromatic hydrocarbon molecules (benzene and anthracene) was calculated using an ab initio molecular orbital method at the MP2(FC)/cc-pVTZ level with basis set superposition error (BSSE) correction. The energy tended to become more negative as the metal atom had a more positive charge and a smaller radius. The energies of Li₂C₆H₆-H₂, Li₂C₁₄H₁₀-H₂, Na₂C₁₄H₁₀-H₂, and MgC₁₄H₁₀-H₂ were −2.7 to −2.2, −4.0 to −3.1, −2.8 to −0.3, and −1.3 kcal/mol, respectively. Most of these energies were more negative than those on the hydrocarbons without metal atoms (ca. −1 kcal/mol). Analyzing the Lennard–Jones type potential with the parameters determined by the MP2 calculations, it was found that these energies mainly consisted of the induction force caused by the positive charge of the metal atom and the dispersion force from the nearest C₆-ring. The energy of BeC₁₄H₁₀-H₂ was more negative (−8.6 kcal/mol) than of the other complexes. The hydrogen molecule in this complex had a comparatively longer H–H distance and a more positive H₂ charge than the others. These data suggest that the hydrogen adsorption on this complex involves a charge transfer process in addition to physisorption interactions. The hydrogen binding energies in some Li₂C₁₄H₁₀-H₂ systems (∼−4.0 kcal/mol) and BeC₁₄H₁₀-H₂ are promising to operate hydrogen storage/release at ambient temperature with moderate pressure.     

Hydrogen bond and internal rotations barrier: DFT study on heavier group‐14 analogues of formamide

A theoretical study on heavier group‐14 substituting effect on the essential property of formamide, strong hydrogen bond with water and internal rotational barrier was performed within the framework of natural bond orbital (NBO) analysis and based on the density functional theory calculation. For heavier group‐14 analogues of formamide (YHONH₂, Y = Si, Ge and Sn), the n_N–π_Y=O conjugation strength does not always reduce as Y becomes heavier, for example, silaformamide and germaformamide have similar strength of delocalization. Heavier formamides prefer being H‐bond donors to form FYO–H₂O complexes to being H‐bond acceptors to form FYH–H₂O complexes. The NEDA analysis indicates that H‐bond energies of FYO–H₂O complexes increase as moving down group 14 due to concurrently stronger charge transfer (CT) and electrostatic attraction and for the FYH–H₂O complexes H‐bond strengths are similar. The model of CTs from FYO to H₂O differs from that at FYH–H₂O complexes, which are contributed not only by aligning lone‐pair orbital of O but also by another lone‐pair orbital. At two lowest lying excited states (the triplet and S₁ excited states), formamide and its heavier analogues form double H‐bonds with H₂O molecule at the same time. The barrier heights of internal rotation become gradually low from C to Sn, formamide (15.73 kcal/mol) > silaformamide (11.73 kcal/mol) > germaformamide (9.45 kcal/mol) > stannaformamide (7.50 kcal/mol) at the CCSD(T)/aug‐cc‐pVTZ//B3LYP/cc‐pVTZ level. NBO analysis indicates that the barrier does not only come from the n_N→π*_YO conjugation, and for heavier analogues of formamide, the n_N→σ*_YO hyperconjugation effect and steric effect considerably contribute to the overall rotational barrier. Copyright © 2013 John Wiley & Sons, Ltd.     

Proton transfer reactions of hydrazine‐boranes

Hydrazine‐borane and hydrazine‐diborane contain, respectively, 15.4 and 16.9 wt% of hydrogen and are potential materials for hydrogen storage. In this work we present the gas‐phase complexation energies, acidities, and basicities of hydrazine‐borane and hydrazine‐bisborane calculated at MP2/6‐311 + G(d,p) level. We also report the release of dihydrogen from both protonated complexes (ΔG_{hydrazine‐borane} = ?20.9 kcal/mol and ΔG_{hydrazine‐bisborane} = ?27.2 kcal/mol) which is much more exergonic than from analogues amine‐boranes. The addition of the first BH₃ to the hydrazine releases 17.1 kcal/mol, and the second addition releases 15.8 kcal/mol. The attachment of BH₃ also increases the N―H acidity of hydrazine by 46.3 kcal/mol. It was found that the B―H deprotonation leads to intramolecular rearrangement. The basicity values for hydrazine‐borane and ‐bisborane are 180 and 172.8 kcal/mol, respectively. For both complexes the protonation centres are located at the boron moiety. The protonated structure of hydrazine‐bisborane is cyclic and can be described as H₂ captured between a negatively charged B―H hydrogen and positive boron (B―H??H2??B). Atoms in molecules analysis are used to investigate bond paths in concerning structures. Copyright © 2015 John Wiley & Sons, Ltd.     

Phase transitions in hydrofullerene C<Subscript>60</Subscript>H<Subscript>36</Subscript> studied by luminescence and Raman spectroscopy at pressures up to 12 GPa

The effect of hydrostatic pressure on the photoluminescence and Raman spectra of hydrofullerene C₆₀H₃₆ was investigated for pressures up to 12 GPa at room temperature. The samples were synthesized by means of high-pressure hydrogenation. The pressure coefficients of the phonon modes were found to be positive and demonstrate singularities at ～0.7 and ～6 GPa. The pressure shift of the luminescence spectrum is unusually small and increases slightly at P≥6 GPa. All observed features are reversible with pressure, and C₆₀H₃₆ is stable in the pressure region investigated.     

Hydrogen incorporation into BN fullerene-like nanostructures: A first-principles study

We performed density functional theory calculations to investigate the possibility of formation of endohedrally H@(BN)_n–fullerene (n: 24, 36, 60) and H@C₆₀ complexes for potential applications in solid-state quantum-computers. Spin-polarized approach within the generalized gradient approximation with the Perdew–Burke–Ernzerhof functional was used for the total energies and structural relaxation calculations. The calculated binding energies show that H atom being incorporated into B₆₀N₆₀ nanocage can form most stable complexes while the B₂₄N₂₄ and C₆₀ nanocages might form unstable complex with positive binding energy. We have also examined the penetration of an H atom into the respective nanocages and the calculated barrier energies indicate that the H atom prefers to penetrate into the B₂₄N₂₄ and B₆₀N₆₀ nanocages with barrier energy of about 0.47 eV (10.84 kcal/mol). Furthermore the binding characteristic is rationalized by analyzing the electronic structures. Our findings reveal that the B₆₀N₆₀ nanocage has fascinating potential application in future solid-state quantum-computers.     

Substituent effect on electron affinity,gas‐phase basicity,and structure of monosubstituted propargyl radicals and their anions: a theoretical study

The substituent effect of electron‐withdrawing groups on electron affinity and gas‐phase basicity has been investigated for substituted propargyl radicals and their corresponding anions. It is shown that when a hydrogen of the α‐CH₂ group or acetylenic CH in the propargyl system is substituted by an electron‐withdrawing substituent, electron affinity increases, whereas gas‐phase basicity decreases. The calculated electron affinities are 0.95 eV (CH?C? CH₂?), 1.15 eV (CH?C? CHF?), 1.38 eV (CH?C? CHCl?), 1.48 eV (CH?C? CHBr?) for the isomers with terminal CH and 1.66 eV (CF?C? CH₂?), 1.70 eV (CCl?C? CH₂?), 1.86 eV (CBr?C? CH₂?) for the isomers with terminal CX at B3LYP level. The calculated gas‐phase basicities for their anions are 378.4 kcal/mol (CH?C? CH₂:^?), 371.6 kcal/mol (CH?C? CHF:^?), 365.1 kcal/mol (CH?C? CHCl:^?), 363.5 kcal/mol (CH?C? CHBr:^?) for the isomers with terminal CH and 362.6 kcal/mol (CF?C? CH₂:^?), 360.4 kcal/mol (CCl?C? CH₂:^?), 356.3 kcal/mol (CBr?C? CH₂:^?) for the isomers with terminal CX at B3LYP level. It is concluded that the larger the magnitude of electron‐withdrawing, the greater is the electron affinity of radical and the smaller is the gas‐phase basicity of its anion. This tendency of the electron affinities and gas‐phase bacisities is greater in isomers with the terminal CX than isomers with the terminal CH. Copyright © 2009 John Wiley & Sons, Ltd.     

NMR Studies of the Reaction Path of the o-H2/p-H2 Spin Conversion Catalyzed by Vaska’s Complex in the Solid State

We have studied the o/p spin conversion of dihydrogen in contact with frozen solutions of Vaska’s complex Ir(CO)Cl(PPh₃)₂ (1) in C₆D₆ and with polycrystalline 1 at 77 K. The main purpose of this study was to elucidate the mechanism of this type of reactions found accidentally previously (Eisenschmid et al JACS 109:8089–8091, 1987 and Eisenberg ACS 24:110–116, 1991). The formation of p-H₂ was followed after thawing of the samples by ¹H nuclear magnetic resonance (NMR) spectroscopy at 298 K, where the oxidative addition of dihydrogen to 1 occurs leading to Vaska’s dihydride Ir(CO)ClH₂(PPh₃)₂ (2) which is known to exhibit para-hydrogen-induced polarization (PHIP). The PHIP signal was shown to be proportional to the concentration of p-H₂ as elucidated from the decrease of the signal of dissolved o-H₂. The reaction was found to be faster for the frozen solution as compared to the polycrystalline powder. Optical microscopy showed that small particles of 1 are separated from the solution during the freezing process, exhibiting a larger surface area as compared to the polycrystalline powder. When a mixture of H₂ and D₂ was exposed to the frozen solutions or to the polycrystalline powder, the formation of HD was observed by ¹H NMR. This finding indicates the presence of a chemical spin conversion involving two dihydrogen molecules. Additional ¹H NMR experiments of dihydrogen in frozen C₆D₆ at 110 K indicated the formation of larger pores containing gaseous H₂ as well as dihydrogen sites in interstitial sites between benzene molecules. Moreover, in the presence of 1, a signal at ?4.5 ppm was observed which was attributed to a dihydrogen in close contact with Ir.     

Electronic structure of the conduction band upon the formation of ultrathin fullerene films on the germanium oxide surface

The results of the investigation of the electronic structure of the conduction band in the energy range 5–25 eV above the Fermi level E_F and the interfacial potential barrier upon deposition of aziridinylphenylpyrrolofullerene (APP-C₆₀) and fullerene (C₆₀) films on the surface of the real germanium oxide ((GeO₂)Ge) have been presented. The content of the oxide on the (GeO₂)Ge surface has been determined using X-ray photoelectron spectroscopy. The electronic properties have been measured using the very low energy electron diffraction (VLEED) technique in the total current spectroscopy (TCS) mode. The regularities of the change in the fine structure of total current spectra (FSTCS) with an increase in the thickness of the APP-C₆₀ and C₆₀ coatings to 7 nm have been investigated. A comparison of the structures of the FSTCS maxima for the C₆₀ and APP-C₆₀ films has made it possible to reveal the energy range (6–10 eV above the Fermi level E_F) in which the energy states are determined by both the π* and σ* states and the FSTCS spectra have different structures of the maxima for the APP-C₆₀ and unsubstituted C₆₀ films. The formation of the interfacial potential barrier upon deposition of APP-C₆₀ and C₆₀ on the (GeO₂)Ge surface is accompanied by an increase in the work function of the surface E_vac–E_F by the value of 0.2–0.3 eV, which corresponds to the transfer of the electron density from the substrate to the organic films under investigation. The largest changes occur with an increase in the coating thickness to 3 nm, and with further deposition of APP-C₆₀ and C₆₀, the work function of the surface changes only slightly.