Structure and energetical properties of metal pivalate chelates M(piv)(3) (M = Al, Ga, In, Tl) by DFT calculations

Pimenov OA, Zhabanov YA, Pogonin AE, Blomeyer S, Puchkov BV. Structure and energetical properties of metal pivalate chelates M(piv)(3) (M = Al, Ga, In, Tl) by DFT calculations. Structural Chemistry. 2015;26(5-6):1443-1450.Structure-related DFT calculations for IIIA metal tripivalates [M(piv)(3)] (M = Al, Ga, In, Tl) were performed. On the potential energy hypersurface (PES) for the Al, Ga, In, and Tl complexes, only a molecular structure of C (3) symmetry based on a distortion of an antiprismatic MO6 coordination polyhedron is found as a minimum. The geometry of C (3v) symmetry corresponds to the first-order saddle points on the PES. The analysis of internal rotation of the tert-butyl groups and plane chelate ring in pivalate molecules was performed also. The structural flexibility within the coordination polyhedron MO6 was found to increase along the series Al -> Ga -> In -> Tl. According to the analyses of the electron density distribution (NBO and QTAIM), the central atom M has no appreciable effect on the geometry of the peripheral tert-butyl groups, so that the most significant differences occur in the coordination polyhedron MO6. The lengthening of the M-O bond and decreasing of the binding energy are correlated with the ionic radius of the metal atom M. This fact proves the ionic binding nature of the title molecules. Appropriate assignment of vibrational modes was carried out by usage of the potential energy distribution analysis among internal coordinates

Molecular Structure of Nickel Octamethylporphyrin—Rare Experimental Evidence of a Ruffling Effect in Gas Phase

The structure of a free nickel (II) octamethylporphyrin (NiOMP) molecule was determined for the first time through a combined gas-phase electron diffraction (GED) and mass spectrometry (MS) experiment, as well as through quantum chemical (QC) calculations. Density functional theory (DFT) calculations do not provide an unambiguous answer about the planarity or non-planar distortion of the NiOMP skeleton. The GED refinement in such cases is non-trivial. Several approaches to the inverse problem solution were used. The obtained results allow us to argue that the ruffling effect is manifested in the NiOMP molecule. The minimal critical distance between the central atom of the metal and nitrogen atoms of the coordination cavity that provokes ruffling distortion in metal porphyrins is about 1.96 Å

Quantum Chemical Study Aimed at Modeling Efficient Aza-BODIPY NIR Dyes: Molecular and Electronic Structure, Absorption, and Emission Spectra

A comprehensive study of the molecular structure of aza-BODIPY and its derivatives, obtained by introduction of one or more substituents, was carried out. We considered the changes in the characteristics of the electronic and geometric structure of the unsubstituted aza-BODIPY introducing the following substituents into the dipyrrin core; phenyl, 2-thiophenyl, 2-furanyl, 3-pyridinyl, 4-pyridinyl, 2-pyridinyl, and ethyl groups. The ground-state geometries of the unsubstituted Aza-BODIPY and 27 derivatives were computed at the PBE/6-31G(d) and CAM-B3LYP/6-31+G(d,p) levels of theory. The time-dependent density-functional theory (TDDFT) together with FC vibronic couplings was used to investigate their absorption and emission spectra