Two different absorption correction methods were compared in order to find out which method is preferable to improve solving and refining a crystal structure. Experiments were performed on the crystal of a tetrakis(μ2-acetato)-diaqua-di-copper(II) complex. The first correction method used was the numerical absorption correction with the aid of a crystal-shape model, and the other was the semi-empirical one, applying scaling routines to the intensity data.

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The structure of 4-methyl-3-[(tetrahydro-2H-pyran-2-yl)oxy]thiazole-2(3H)thione (MTTOTHP) was investigated using X-ray diffraction and computational chemistry methods for determining properties of the nitrogen-oxygen bond, which is the least stable entity upon photochemical excitation. Experimentally measured structure factors have been used to determine and characterize charge density via the multipole model (MM) and the maximum entropy method (MEM). Theoretical investigation of the electron density and the electronic structure has been performed in the finite basis set density functional theory (DFT) framework. Quantum Theory of Atoms In Molecules (QTAIM), deformation densities and Laplacians maps have been used to compare theoretical and experimental results. MM experimental results and predictions from theory differ with respect to the sign and/or magnitude of the Laplacian at the N-O bond critical point (BCP), depending on the treatment of n values of the MM radial functions. Such Laplacian differences in the N-O bond case are discussed with respect to a lack of flexibility in the MM radial functions also reported by Rykounov et al. [Acta Cryst. (2011), B67, 425-436]. BCP Hessian eigenvalues show qualitatively matching results between MM and DFT. In addition, the theoretical analysis used domain-averaged fermi holes (DAFH), natural bond orbital (NBO) analysis and localized (LOC) orbitals to characterize the N-O bond as a single bond with marginal character. Hirshfeld atom refinement (HAR) has been employed to compare to the MM refinement results and/or neutron dataset C-H bond lengths and to crystal or single molecule geometry optimizations, including considerations of anisotropy of H atoms. Our findings help to understand properties of molecules like MTTOTHP as progenitors of free oxygen radicals.

A series of three new metal complexes with selenadiazoloquinolones, known as broad spectrum antibiotics in clinical praxis, namely [Co(E4h)2(phen)]∙8H2O (1), [Ni(E4h)2(phen)]∙8H2O (2) and [Cu(E4h)(phen)Cl)]∙5H2O (3), have been synthesized and fully...

Two tridentate (L1=2,6-bis(1-(3,5-di-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine and L2=2,6-bis(1-(4-tert-butylbenzyl)-1H-benzimidazol-2-yl)pyridine) and one didentate ligand (L3=1-(4-tert-butylbenzyl)-2-pyridine-2-yl-1H-benzimidazol) were used for the synthesis of eight mononuclear Fe(II) compounds 1-8 containing miscellaneous counterions. Single-crystal X-ray diffraction analysis confirmed the...

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An extensive characterization of [Ti(C22H18N2O6)]·H2O was performed by topological analysis according to Bader's quantum theory of atoms in molecules (QTAIM) from the experimentally (multipole model) and theoretically (DFT) determined electron density. To the best of our knowledge, this study is the first example of an experimental electronic structure of a coordination compound in which a peroxo anion is bonded to a 3d central atom. The titanium coordination polyhedron could be described as a deformed tetrahedral pyramid if the midpoint of the peroxide O—O bond (side-on mode) is considered to be in the quasi-apical position. According to the multipole model (MM) results, the titanium atom has a positive QTAIM charge of 2.05 e− which does not correspond to the formal Ti (IV) oxidation state. On the other hand, the peroxo oxygen atoms O(1) and O(2) have MM QTAIM charges of −0.27 and −0.12, respectively. This asymmetric charge density distribution on the peroxo oxygens is in agreement with the distorted orientation of the O2 moiety with respect to the titanium atom. Despite the fact that the overall MM charge of the O2 moiety is more remote from the formal −2 charge than from neutral O2, the O—O distance remains close to that in the peroxo O2 2− anion. In the case of DFT results, the titanium atom charge is also found to be close to +2, the O2 x− moiety charge is around −1, the optimized O—O distance is shorter by only ca 0.04 Å than the experimental value of 1.5005 (16) Å, and the DFT d-populations on titanium are found to be lower than the experimental MM value. This study is the first experimental electronic structure of a transition metal peroxo complex.