Search

This work explores an efficient and numerically accurate procedure to obtain the Fukui function from fractional orbital occupation calculations. The energy- and density-linearity conditions are investigated in the context of using optimally tuned range-separated hybrid functionals for the calculation of the Fukui function. The methodology is then used to study the reactivity of organic radicals exhibiting energetic inversion between the singly occupied molecular orbital (SOMO) and the highest occupied molecular orbital (HOMO), that is, SOMO–HOMO inversion (SHI). The Fukui function correctly identifies the reactive sites of the molecules investigated, but additional computed quantities, such as radical reaction energies and vertical ionization potentials, are needed to distinguish SHI systems from conventional radicals.

This study confirms the hypothesis that [MnCl3(OPPh3)2] (1) and acetonitrile-solvated MnCl3(i.e., [MnCl3(MeCN)x]) can be used as synthons to prepare Mn(III) chloride complexes with facially coordinating ligands. This was achieved through the preparation and characterization of six new {MnIIICl} complexes using anionic ligands TpH(tris(pyrazolyl)borate) and TpMe(tris(3,5-dimethylpyrazolyl)borate). The MnIII–chloride dissociation and association equilibria (Keq) and MnIII/IIreduction potentials were quantified in DCM. These two thermochemical parameters (Keqand E1/2), in addition to the known Cl-atom reduction potential in DCM, enabled the quantification of the Mn–Cl bond dissociation (homolysis) free energy of 21 and 23 ± 7 kcal/mol at room temperature for R = H and Me, respectively. These are in reasonable agreement with the bond dissociation free energy (BDFEM–Cl) of 34 ± 6 kcal/mol calculated using density functional theory. The BDFEM–Clof 1was also calculated (25 ± 6 kcal/mol). These energies were used in predictive C–H bond reactivity.

Two series of zinc salts, [EtZn][A] and Zn[A]2, with weakly coordinating anions [A]−as counterions have been prepared, and their activities as catalysts for hydrosilylation reactions of 1-hexene, benzophenone, and acetophenone have been investigated. The counterions and per- and partially chlorinated 1-ammonio-closo-dodecaborate anions [Me3NB12Cl11]−[1]−, [Pr3NB12H5Cl6]−[2]−, [Bu3NB12H4Cl7]−[3]−, and [Hex3NB12H5Cl6]−[4]−were chosen as potential and more readily available alternatives to carborate anions such as [CHB11Cl11]−and [HexCB11Cl11]−. The basicity of anion [4]−was determined as being close to that of the triflimide anion [N(SO2CF3)2]−, and the fluoride ion affinities (FIAs) of compounds [EtZn][2] and Zn[2]2are lower than those of the Lewis acids B(C6F5)3and Zn[HexCB11Cl11]2. The higher anion basicity and the resulting lower Lewis acidity of the zinc centers result in low activity in 1-hexene hydrosilylation catalysis and only moderate activity in the hydrosilylation catalysis of benzophenone and acetophenone.

A new database, VROA36, is introduced to investigate the performance of computational approaches for vibrational Raman optical activity (VROA) calculations. The database is composed of 36 molecules with known experimental VROA spectra. It includes 93 conformers. Normal modes calculated with B3LYP-D3(BJ)/def2-TZVP are used to compute the VROA spectra with four functionals, B3LYP-D3(BJ), ωB97X-D, M11, and optimally tuned LC-PBE, as well as several basis sets. SimROA indices and frequency scaling factors are used to compare calculated spectra with each other and with experimental data. The four functionals perform equally well independently of the basis set and usually achieve good agreement with the experimental data. For molecules in near- or at-resonance conditions, the inclusion of a complex (damped) linear response approach is important to obtain physically meaningful VROA intensities. The use of any of the tested functional approximations with the def2-SVPD Gaussian-type basis set, or a basis of similar flexibility, can be recommended for efficient and reliable theoretical VROA studies.