Université de Fribourg

Density functional theory study of the Jahn-Teller effect in cobaltocene

Zlatar, Matija ; Schläpfer, Carl-Wilhelm ; Penka Fowe, Emmanuel ; Daul, Claude A.

In: Pure and Applied Chemistry, 2009, vol. 81, no. 8, p. 1397-1411

A detailed discussion of the potential energy surface of bis(cyclopentadienyl)cobalt(II), cobaltocene, is given. Vibronic coupling coefficients are calculated using density functional theory (DFT). Results are in good agreement with experimental findings. On the basis of our calculation there is no second-order Jahn–Teller (JT) effect as predicted by group theory. The JT distortion can be...

Université de Fribourg

Possible ring structures of armchair single-walled carbon nanotubes

Tamilmani, Venkatachalam ; Daul, Claude A. ; Jenny, Titus A.

In: Chimia, 2006, vol. 60, no. 4, p. 228-230

Energetics and the electronic structure of various types of single-walled carbon nanotubes have been investigated by using Density Functional Theory. Armchair [n,n], zigzag [n,0] and chiral [n,m] C₄₀H₂₀ nanotubes have been considered. Calculations show that the armchair isomer is the most stable among the three types and they further reveal the factors that stabilize this isomer....

Université de Fribourg

Asymmetric μ2-1,1-azido bridged copper(II) complex: Synthesis, X-ray structure, magnetic study and DFT calculations

Zbiri, Mohamed ; Saha, Sandip ; Adhikary, Chandan ; Chaudhuri, Siddhartha ; Daul, Claude A. ; Koner, Subratanath

In: Inorganica Chimica Acta, 2006, vol. 359, p. 1193

A new rare variety asymmetric μ2-1,1-azido bridged copper(II) complex has been synthesized and characterized structurally and magnetically. The complex [Cu2L2(μ2-1,1-N3)2] · H2O · CH3OH (L = 1-(N-ortho-hydroxyacetophenimine)-2-aminoethane) (1), crystallizes in monoclinic space group, P21/n, with a = 9.469(4) Angstrom capital A, ring, b = 12.526(8) Angstrom capital A, ring, c = 12.899(10)...

Université de Fribourg

Chemical bonding in molecules and complexes containing d-elements based on DFT

Atanasov, Mihail ; Daul, Claude A. ; Penka Fowe, Emmanuel

In: Monatshefte für Chemie / Chemical Monthly, 2005, vol. 136, no. 6, p. 925-963

Metal–ligand bonding in transition metal halide molecules and complexes with different central ions, oxidations states, and coordination numbers: CrIII X₆³⁻, CrIVX₄, CrIIX₂ (X = F,Cl,Br,I), MIIICl₆³⁻(M = Mo,W), MIII (H₂O)₆³⁺(M = Cr,Co) and Re₂Cl₈²⁻ has...

Université de Fribourg

Density functional study of nitroprusside: Mechanism of the photochemical formation and deactivation of the metastable states

Buchs, M. ; Daul, Claude A. ; Manoharan, P. T. ; Schläpfer, Carl-Wilhelm

In: International Journal of Quantum Chemistry, 2003, vol. 91 (3), p. 418-431

In this article, we present a theoretical investigation about the mechanism of the photochemical formation and deactivation of the metastable states observed in nitroprusside ions. The quantum chemical calculations are based on density functional theory. The peculiar photochemical and photophysical behavior of this molecule has attracted chemists' interest for a while. Due to this interest, many...

Université de Fribourg

Hydrogen bond stabilization in Diels–Alder transition states: The cycloaddition of hydroxy-ortho-quinodimethane with fumaric acid and dimethylfumarate

Tamilmani, Venkatachalam ; Daul, Claude A. ; Lage Robles, Jaime ; Bochet, Christian G. ; Venuvanalingam, P.

In: Chemical Physics Letters, 2005, vol. 406, no. 4, p. 355-359

DFT investigations on the mechanism of Diels–Alder reactions of a hydroxy-ortho-quinodimethane with fumaric acid derivatives were performed to understand the origin of the syn or anti configuration of the adducts. The diene hydroxyl group and the dieneophile carboxyl group show hydrogen bonding in the transition state, significantly favouring the syn product. This reaction is poorly...