Insertion reaction of ethylene into the Rh–H bond: A comparative theoretical study

Enantioselective Synthesis of 4-Methyl-3,4-dihydroisocoumarin via Asymmetric Hydroformylation of Styrene Derivatives

Enantioenriched aldehydes are produced through asymmetric hydroformylation of styrene derivatives using BIBOP-type ligands. The featured example is enantioselective synthesis of 4-methyl-3,4-dihydroisocoumarin, which was prepared in a 95.1:4.9 enantiomeric ratio from asymmetric hydroformylation of ethyl 2-vinylbenzoate followed by in situ lactonization during the reduction process. The conditions are compatible with both electron-rich and electron-poor substituents.

QUANTUM CHEMICAL STUDY OF CISPLATIN-WATER COMPLEXES: AN INVESTIGATION OF ELECTRON CORRELATION EFFECTS

The interaction of cisplatin ([ Pt(NH3)2Cl2] ) with water was studied for distinct complexation modes aiming to investigate the level of calculation required to describe transition metal complexes of biological relevance, where large scale ab initio post-Hartree-Fock calculations are usually precluded. Coupled Cluster (CCSD(T)) single point calculations employing MP2 and MP4(SDQ) optimized geometries and good quality basis sets, using effective core potential for platinum atom, are reported as well as Density Functional Theory (DFT) results employing various exchange-correlation functional. The importance of electron correlation effects for the calculation of interaction energies is discussed. The extension of correlation energy recovered by DFT was assessed considering the CCSD(T) results as reference. The recently developed M06-2x functional showed the best overall agreement with CCSD(T) calculations. The relative importance of the electrostatic and dispersion contributions to the interaction energy was estimated with the aid of the atoms in molecules theory and also using an empirical approach based on the multipole expansion method. It was found a strong dependence of the energy contributions on the spatial orientation of water and cisplatin monomers, with the electrostatic contribution dominating the interaction energy for the lowest energy equilibrium structures.

AN EVALUATION OF QUANTUM CHEMICAL CALCULATIONS OF REACTION ENERGIES FOR CATALYTIC ACTIVATION PROCESSES: THE ACTIVATION OF PROPANE BY A RHODIUM CATALYST REVISITED

In this paper we report the state of the art CCSD(T)//MP2 ab initio calculations for the activation of propane by cyclopentadienyl carbonyl rhodium, (Cp)Rh(CO) , using the effective core potential of Hay and Wadt (LANL2DZ) for rhodium atom and the correlated consistent polarized valence double-ξ basis set (cc-pVDZ) for C , H and O atoms. The CCSD(T) energy values are used as reference to assess the effect of electron correlation on the reaction energies, as well as the performance of density functional theory (DFT) energy values using various functionals. An investigation on the accuracy of DFT results is relevant since their use in calculations involving large molecular systems is a computationally efficient strategy that enables us to tackle important problems in organometallics field and supramolecular chemistry. Our results for the small model system show that all DFT functionals used here correctly predict the CCSD(T) energy pattern and also reproduce very satisfactorily the MP2 geometrical parameters. The BP86, PBE1PBE and PW91 functionals exhibited the best agreement with structural parameters and relative energy values as compared with ab initio post-Hartree–Fock results, showing a potential use in theoretical investigations on larger systems.

How the choice of a computational model could rule the chemical interpretation: the Ni(II) catalyzed ethylene dimerization as a case study

In this article, we present a critical study of the theoretical protocol used for the determination of the nickel(II) catalyzed ethylene dimerization mechanism, considered as a representative example of the various problems related to the modeling a catalytic cycle. The choice of an appropriate computational procedure is indeed crucial for the validity of the conclusions that will be drawn from the computational process. The influence of the exchange-correlation functional on energetic profiles and geometries, the role of the basis set describing the metal atom, as well as the importance of the chosen molecular model, have been thus examined in details. From the obtained results, some general conclusions and guidelines are presented, which could constitute useful warnings in modeling homogenous catalysis. Besides, the database constituted by our high-level calculations can be used within benchmarking procedures to assess the performances of new computational methods based on density functional theory.