The adsorption of methanol on V₂O₅ and its mild oxidation to formaldehyde has been studied applying density functional theory. The model used throughout is a cluster model saturated by hydrogen atoms. It is shown that the adsorption of methanol is energetically favored if the cluster is partially reduced (i.e., protonated because of the dissociative adsorption of water). Methanol behaves as a soft base and adsorbs as a methoxonium cation. The proposed mechanism is based on two steps, the first being the dissociation of methanol to form a methoxy group on the surface. This dissociation occurs between the oxygen and the carbon atoms of methanol. Finally, for the second step, which corresponds to the desorption of formaldehyde, the calculations show that filling of the vanadyl oxygen vacancy created by formaldehyde desorption is crucial to cope with an energetically feasible reaction pathway.

Nitrosyl metal complexes, such as the sodium nitroprusside, have attracted chemists' interest for more than 30 years. The existence of long-lived metastable states easily populated by irradiation are the principal reason for this interest. Those long-lived states are interesting either for technical applications or for fundamental research. In this work, we present a comparative density functional theory (DFT) study of the ground state of two different nitrosyl compounds:  sodium nitroprusside and cyclopentadienylnitrosylnickel(II).

The photochemical reactions of the nitroprusside and the CpNiNO complexes are explained on the basis of ΔSCF and time-dependent density functional theory (TD-DFT) calculations. Both similarities and differences in the photochemical processes are highlighted.

Vertical excitations calculated for the CrO₄^2- , MnO₄^2-  , RuO₄, CrF₆, FeCp₂, RuCp₂ and CpNiNO species are compared to experimental spectra. The results obtained from the time-dependent density-functional theory−response theory (TD-DFRT) method are compared to both previously reported ΔSCF calculations and experiment. The results show that, in general, excited states of metal oxide and metallocene compounds are well described by TD-DFRT. However, serious difficulties are met with the CrF₆ system.

The ground- and excited-state properties of both [Ru(bz)₂]²⁺ and crystalline bis(η⁶-benzene)ruthenium(II) p-toluenesulfonate are investigated using the density functional theory. A symmetry-based technique is employed to calculate the energies of the multiplet structure splitting of the singly excited triplet states. For the crystalline system, a Buckingham potential is introduced to describe the intermolecular interactions between the [Ru(bz)₂]²⁺ system and its first shell of neighbor molecules. The overall agreement between experimental and calculated ground- and excited-state properties is good, as far as the absolute transition energies, the Stokes shift, and the geometry of the excited states are concerned. The calculated d-d excitation energies of the isolated cluster are typically 1000-2000 cm^-1 too low. An energy lowering is obtained in a_1g → e_1g(³E_1g) excited state when the geometry of [Ru(bz)₂]²⁺ is bent along the e_1u Renner-Teller active coordinate. It vanishes as the crystal packing is taken into account.

The adsorption of methanol on the (110) surface of γ-alumina was investigated using both ab initio and density functional theory quantum chemical methods. A [Al₃O₉H₁₀]⁺ cluster model comprising one tetrahedral and two octahedral aluminum cations were used to describe the surface and the mechanism of adsorption of methanol. This has allowed us to rationalize the stable structures of adsorbate and the mode of bonding. The IR frequency shifts between the gas phase and the adsorbed species were also calculated and they exhibit good agreement with experiment.

The ground- and excited-state properties of both gas phase and crystalline ruthenocene, Ru(cp)₂, are investigated using density functional theory. A symmetry-based technique is employed to calculate the energies of the multiplet splittings of the singly excited triplet states. For the crystalline system, a Buckingham potential is introduced to describe the intermolecular interactions between a given Ru(cp)₂ molecule and its first shell of neighbors. The overall agreement between experimental and calculated ground- and excited-state properties is very good as far as absolute transition energies, the Stokes shift and the geometry of the excited states are concerned. An additional energy lowering in the ³B₂ component of the 5a1′→4e1″ excited state is obtained when the pseudolinear geometry of Ru(cp)₂ is relaxed along the low-frequency bending vibration.

The condensed Fukui functions fk of maleimide (1H-pyrrole-2,5-dione) have been calculated using a numerical integration scheme implemented in the deMon program package. The condensed functions show that soft nucleophiles interact with the α carbon atoms, whereas hard nucleophiles interact with the carbonyl carbon atoms, in accordance with the experimental evidence. The present method yields extremely few dispersed values of fk, whatever the basis sets, the numerical grids, and the exchange-correlation functionals used. Finally, the validity of the method has been successfully tested on a set of organic and organometallic molecules.

The coordination properties of ortho- and meta-substituted [(2-diphenylphosphanylethyl)phenyl]methanol 4a and 4b toward ruthenium(II) have been investigated. To ensure coordination of both the arene and the tethered phosphine, the labile ruthenium arene dimer [RuCl₂(EtO₂CC₆H₅)]₂ (7) was synthesized and structurally characterized. Both the ortho and meta isomers [Ru(4a)Cl₂] (9a) and [Ru(4b)Cl₂] (9b) were characterized by X-ray crystallography. The lack of reactivity of the benzylic alcohol functionality in complexes 9a and 9b toward various P and C electrophiles is rationalized with extended Hückel calculations.

The edge-bridged tetrahedral geometry of five-coordinate d0 complexes [MD2L3] with strong Ï€-donors D is analyzed with extended Hückel methodology as well as density functional theory. It is shown that this geometry, also encountered in bent metallocene systems [MCp2L3], can be considered as a distortion of a regular trigonal bipyramid arising from a second-order Jahn−Teller distortion of e‘ symmetry (in D3h) and corresponds to a deformation along a reversed-Berry pathway. This model was tested with a structure-correlation analysis of all experimentally determined [MD2L3] structures, thus allowing a mapping of the reversed-Berry pathway. The catalytic potential of these complexes and their isolobal relationship to [MCp2L3] are emphasized.

Quantum chemical calculations have been performed using density functional theory to model the mechanism of selective catalytic reduction of NO by NH3 on vanadium oxide. The reaction is initiated by NH3 adsorption on a Brønsted site modeled as a dimer cluster model representative of vanadium oxide, containing a terminal VO adjacent to a V−OH group. The calculations indicate that the adsorbed NH3 behaves as NH4+, which is supported by calculated IR spectra. Subsequently NO reacts with this activated NH3 to yield NH2NO and finally the reaction products N2 and H2O. The present results give support to a dual-site Eley−Rideal-type mechanism involving a Brønsted site and agree with isotopic labeling studies.

Quantum chemical calculations using the density functional theory were performed to model the mechanism of selective catalytic reduction of NO by NH3 on a supported vanadium oxide monolayer. In the first step, the adsorption of NH3 on a bimetallic cluster representative of vanadium oxide, containing a terminal VO adjacent to a VOH group, was investigated. The calculations indicate that NH3 may be strongly adsorbed on VOH (Brönsted acid site) as NH+4(ads); subsequently, NO reacts with this activated NH3 to yield the reaction products N2 and H2O. The present results give support to a dual-site Eley-Rideal-type mechanism involving a Brönsted site.

The ground and excited state properties of the Cr³⁺ ion doped into the cubic host lattices Cs₂NaYCl₆ and Cs₂NaYBr₆ have been studied using density functional theory. A new symmetry based technique was employed to calculate the energies of the multiplets ⁴A_2g, ⁴T_2g, ²E_g, and ⁴T_1g. The geometry of the CrX^{3 -Â} ₆ cluster was optimized in the ground and excited states. A Madelung correction was introduced to take account of the electrostatic effects of the lattice. The experimental Cr–X distance in the ground state can be reproduced to within 0.01 Ã… for both chloride and bromide systems. The calculated d–d excitation energies are typically 2000–3000 cm^–1 too low. An energy lowering is obtained in the first ⁴T_2g excited state when the octahedral symmetry of CrX^{3 -Â} ₆ is relaxed along the eg Jahn–Teller coordinate. The geometry corresponding to the energy minimum is in excellent agreement with the ⁴T_2g geometry derived from high-resolution optical spectroscopy of Cs₂NaYCl₆:Cr³⁺. It corresponds to an axially compressed and equatorially elongated CrX^{3 -Â} ₆ octahedron.

The luminescence of [CrX₆]^3– X=Br^–, Cl^– has been studied through density functional theory (DFT) using both deMon and ADF codes. Multiplet energies⁴A₂,²E,⁴T₂, and⁴T₁ have been expressed as energies of non-redundant single determinants and calculated as in Ref. [1]. The influence of the metal ligand distance on the multiplet energies has been investigated. Of particular interest to this work is the Jahn-Teller effect distortion. We found that the system moves to a more stable geometry when the axial bond length is compressed and the equatorial one elongated in agreement with the experimental value.