Synthesis and crystal structure of the copper(II) valerate complex with nicotinamide

A coordination compound of copper(II) valerate with nicotinamide, [CuL(C₄H₉COO)₂]₂ (I), has been synthesized, and its crystal structure has been determined by X-ray crystallography. The crystals of I are triclinic: a = 9.1245(9) Å, b = 9.8572(6) Å, c = 11.0944(9) Å, α = 73.51(1)°, β = 79.917(6)°, γ = 72.161(7)°, Z = 2, space group $P\bar 1$ . In the centrosymmetric binuclear molecule of I, the copper atoms (Cu...Cu′, 2.621 Å) are linked through four bidentate chelating valerate ligands (av., Cu-O 1.969 Å). The coordination polyhedron of the Cu atom is a tetragonal pyramid with the nitrogen atom of the pyridine ring in the apical position at a longer distance (Cu-N, 2.190 Å).     

Unusual Substitution in Hydrazinobenzoic Acid upon Complexation. Crystal and Molecular Structure of Hydrazinobenzoic Acid Hydrochloride

Crystallography Reports - The crystal and molecular structure of 2-hydrazinobenzoic acid was determined. In solution in the presence of copper(II) chloride, 2-hydrazinobenzoic acid is transformed...     

Five-coordinate Co(II) complexes with nitrilotriacetic acid: Crystal structures of Ca[Co(Nta)X] · nH2O (X − = Cl, Br, or NCS)

The synthesis and X-ray diffraction study of three Ca[Co(Nta)X] · nH₂O complexes [X ^? = Cl, n = 2.3 (I); X ^? = Br, n = 2 (II); and X ^? = NCS, n = 2 (III)] are performed. The main structural units of crystals I–III are the [CoX(Nta)]^2? anionic complexes and hydrated Ca²⁺ cations. The anionic complexes have similar structures. The coordination of the Co²⁺ atom in the shape of a trigonal bipyramid is formed by N + 3O atoms of the Nta ^3? ligand and the X ^? anion in the trans position with respect to N. In structures I–III, the Co-O and Co-N bond lengths lie in the ranges 1.998–2.032 and 2.186–2.201 Å, respectively. The Co-X bond lengths are 2.294 (I), 2.436 and 2.445 (II), and 1.982 Å (III). The environments of the Ca²⁺ cations include oxygen atoms of one or two water molecules and six or seven O(Nta) atoms with the coordination number of 9 in I or 8 in II and III. The Ca-O(Nta) bonds form a three-dimensional framework in I or layers in II and III. Water molecules are involved in the hydrogen bonds O(w)-H···O(Nta), O(w)-H···X, and O(w)-H···O(w). Structural data for crystals I–III are deposited with the Cambridge Structural Database (CCDC nos. 287 814–287 816).     

Synthesis and crystal structure of the sodium complex with 2-(diphenylacetyl)indandione-1,3

The sodium complex with 2-(diphenylacetyl)indandione-1,3 (HL) have been synthesized and studied by X-ray diffraction analysis. Crystals of [Na₄(H₂O)₄L₄] (I) precipitated from aqueous acetone are monoclinic, Z = 2, space group P2₁/c, a = 12.171(1) Å, b = 10.527(1) Å, c = 29.777(2) Å, β = 97.455(1)°. The structure of compound I is based on a centrosymmetric tetranuclear [Na₄O₁₂] cage. Two central Na(2) atoms are coordinated to four O atoms of two L ligands. The central and peripheral atom polyhedrons [Na(2)O₆] and [Na(1)O₅] are joined by a common edge formed by two O atoms of two L ligands. Tetranuclear moieties are joined into the framework by hydrogen bonds, numerous C-H-π contacts, and π-π stacking-contacts between the conjugated and aromatic ligand systems of neighboring tetramers.     

Intramolecular Interactions of Phosphor-Containing Groups with an Aromatic Fragment in Different Conformations

Abstract

Geometrical and electronic structure of conformers was studied by optical spectroscopy and quantum chemistry methods. The interaction mechanism of phosphor-containing groups with an aromatic fragment in YC₆H₄PX₂ (Y = H, Cl, Me, OMe, NMe₂, C(O)OR; × = Alk, OAlk, NAlk₂, Cl) and YC₆H₄P(Z)X₂ (Y = H, C1, Me, OMe, NMe₂; × = Alk, OAlk, NAlk₂, F, C1; Z = O, S) compounds is discussed. In case of bisector conformation (A), where the benzene ring plane coincides with a XPX-angle bisectrix, ll-acceptor action of phosphorus-containing groups increases with X varying in a series: Alk <NAlk₂ ≈ OAlk ≤ F4 << C1. These properties are displayed in ground and excited states of molecules, and are determined by interaction of PX₂ and P(Z)X₂ vacant group orbitals antisymmetric with respect to bisector plane with aromatic fragment π-orbitals. For phosphorchloride groups [sgrave]-π-conjugation dominates and the d-π-conjugation contribution is small. π-acceptor effect for P(0)X₂is weaker than for PX₂ and P(S)X₂ groups (especially in excited states) which is due to competitive transfer of electron density from oxygen to PX₂ fragment. In case of the gonal conformation (B) where benzene ring and bisector plane of PX₂ fragment are perpendicular, π-donor effect of PAlk₂ group is found to be 2–4 times weaker than for NAlk₂. According to quantum-chemical calculations with the MNDO method ArPX₂ the stabilization of conformer B for ArPX₂ increases in a series X: C1 <C=N <F <H <CH₃; and for ArP(0)X₂ the main conformation is (A).     

Specific features of the structures of d 2-Rhenium(V) monomeric octahedral oxo complexes: I. Structure of d 2-Re(V) mono-oxo compounds with halogen ligands trans-positioned to O(oxo) ligands

The specific features of the structure of rhenium(V) mononuclear octahedral mono-oxo complexes with halogen ligands (F, Cl, Br), trans-positioned to multiply bonded oxo ligands, are considered.     

Synthesis of metal complexes with 2-[bis(2-phenylethyl)-thiophophorylhydroxymethyl]-1-organilimidazoles. Crystal structure of ZnCl2 · 2L

The reactions of Zn(II), Cd(II), Cu(II), Co(II), Pd(II) dichlorides with 2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-1-organilimidazoles (L¹–L⁴) were studied. The novel complexes were synthesized and characterized by IR and NMR spectroscopies. Depending on the nature of imidazolephosphinesulfide, both monodentate (at the “pyridine” N(1) atom of heterocycle) and the N,S-bidentate binding of the ligand by a metal can be realized in the above metal complexes. The structure of the complex ZnCl₂ · 2L⁴(I) (L⁴ = 2-[bis(2-phenylethyl)thiophosphorylhydroxymethyl]-1-ethylbenzimidazole) was studied by X-ray diffraction. One of the two independent L⁴ molecules performs the solvate function, while another one, together with two Cl atoms, is coordinated through the atoms N(1) and S to the Zn atom at the vertices of a slightly distorted tetrahedron. The molecule of the complex is united with the solvate molecule into [ZnCl₂L₄]L⁴ associates by strong intermolecular hydrogen bonds to give nonplanar four-membered H-cycle OH₂N.     

Crystal structure of strontium Di[bis(iminodiacetato)cobaltate(III)] pentahydrate,Sr[<Emphasis Type="Italic">cis</Emphasis>(N)-Co(<Emphasis Type="Italic">Ida</Emphasis>)<Subscript>2</Subscript>]<Subscript>2</Subscript> · 5H<Subscript>2</Subscript>O

Compound Sr[cis(N)-Co(Ida)₂]₂ · 5H₂O (I) is synthesized and its crystal structure is determined. The crystals are built of [Co(Ida)₂]^? anionic complexes, [Sr(H₂O)₃]²⁺ hydrated cations, and crystallization water molecules. Two independent anions are located on rotation axis 2 and have close structures. A distorted octahedral coordination of Co³⁺ atoms is formed by two N atoms and four O atoms of two Ida ^2? ligands [Co-N, 1.932(3) and 1.940(3) Å; Co-O, 1.879–1.899(3) Å]. [Sr(H₂O)₃]²⁺ cations randomly occupy half of the positions in the vicinity of centers of inversion. In addition to three water molecules, the environment of the Sr²⁺ atom includes five O atoms of five Ida ^2? ligands [Sr-O, 2.487(3)-2.889(5) Å]. Because of the disordering of [Sr(H₂O)₃]²⁺ cations, the structural function of the Ida ^2- ligands varies from tridentate chelate to pentadentate bridging chelate. Sr-O and hydrogen bonds connect structural elements into a three-dimensional framework. The structure of I is compared with that of a related compound Sr[CoEdta]₂·9H₂O (II). It is shown that the formation of N-H…O hydrogen bonds, which connect [Co(Ida)₂]^? anionic complexes in I into compact chains, is an important factor leading to the difference between packings I and II.     

Synthesis and characteristics of the dioxonium salt based on tartratogermanate acid. Crystal and molecular structure of (H5O2)[(H2O)2Ge(μ-Tart)2Ge(OH)] · 4H2O

Tartratogermanate acid was obtained for the first time as the dioxonium complex (H₅O₂)[(H₂O)₂Ge(??-Tart)₂Ge(OH)] · 4H₂O (I) by the reaction of germanium tetrachloride with D-tartaric acid (H₄Tart) in 85% acetic acid. The complex was characterized by elemental analysis data, thermogravimetry, and IR spectroscopy. X-ray diffraction analysis for I was performed. The crystals are orthorhombic, a = 15.862(3) ?, b = 13.401(3) ?, c = 8.6800(17) ?, V = 1845.1(6) ?³, Z= 4, space group P2₁2₁2, R1= 0.0520 for 5152 reflections with I > 2??(I). Compound I is composed of the dimeric complex anions [(H₂O)₂Ge(??-Tart)₂Ge(OH)]^?, dioxonium cations, and water molecules of crystallization. In the anion, the Ge(1) (CN = 6) and Ge(2) (CN = 5) atoms are linked by two chelating bridging fully deprotonated tartaric acid ligands through two carboxyl (average Ge-O, 1.883(4) and 1.893(4) ?, respectively) and two alcohol (average Ge-O, 1.859(4) and 1.779(4) ?, respectively) oxygen atoms. The coordination polyhedron of Ge (1) is completed to a distorted octahedron by the oxygen atoms of two water molecules (Ge(1)-O(H₂O), 1.933(4) and 1.854(3) ?). The Ge(2) coordination polyhedron is trigonal bipyramid. Its base is formed by two alcohol oxygen atoms of two bridging Tart^4? ligands and the oxygen atom of the terminal hydroxy group (Ge-O, 1.764(4) ?). The axial positions are occupied by the carboxyl oxygen atoms of the Tart^4? ligands (the O(5)Ge(2)O(11), 176.84(16)°). In the crystal, the structural units are combined by hydrogen bonds to a three-dimensional framework.     

Weighted pseudoinverses and weighted normal pseudosolutions with singular weights

Weighted pseudoinverses with singular weights can be defined by a system of matrix equations. For one of such definitions, necessary and sufficient conditions are given for the corresponding system to have a unique solution. Representations of the pseudoinverses in terms of the characteristic polynomials of symmetrizable and symmetric matrices, as well as their expansions in matrix power series or power products, are obtained. A relationship is found between the weighted pseudoinverses and the weighted normal pseudosolutions, and iterative methods for calculating both pseudoinverses and pseudosolutions are constructed. The properties of the weighted pseudoinverses with singular weights are shown to extend the corresponding properties of weighted pseudoinverses with positive definite weights.