Calculation of harmonic force constants,vibrational frequencies and integrated intensities of some organic molecules using the MINDO—Forces method

The harmonic force constants, vibrational frequencies and integrated intensity ratios of CH₂, H₂O, CH₂O, C₂H₂, CO₂, HCN, CH₃, CH₄, and C₂H₄ have been calculated using the MINDO—FORCES program and the Pulay method for the calculation of the molecular force constants. The results obtained are in general quite satisfactory when compared with available literature values. The results are, however, not as satisfactory in case of molecules containing heteroatoms, due to the neglect of some dipolar repulsion integrals for the heteroatoms by the MINDO/3 method. Calculated integrated intensities for CH₃ and C₂H₄ agree well with experimental results. The calculated integrated intensities for other molecules are obtained for the first time and no comparison with published data is therefore possible.Part of the M.Sc. Thesis of K. H. A. 1978.     

Complexation of Ni (II) and Zn(II) ions by 3-(1-naphthyI)-2-mercaptopropenoic acid

The complexation equilibria between Ni(II) and Zn(II) metal ions with 3-(1-naphthyl)-2-mercaptopropenoic acid (H₂NMP) were studied by glass electrode potentiometry, at 25 °C and 1.0 mol·dm^–3 in NaClO₄ as constant ionic medium in 50% (v/v) water-ethanol solutions. Formation constants for the complexes Ni(NMP), Ni(NMP) ₂ ^2– , Zn(NMP) and Zn(NMP) ₂ ^2– , refined by the MINIGLASS program, are reported.     

Synthesis and Characterization of Novel Monoazo N‐Ester‐1,8‐Naphthalimide Disperse Dyestuffs

Five novel monoazo disperse dyestuffs based on N‐ester‐1,8‐naphthalimide were synthesized. Acenaphthene was nitrated, then oxidized to 4‐nitro‐1,8‐naphthalic anhydride. 4‐Nitro‐1,8‐naphthalic anhydride was reacted with methyl and ethyl glycinate in alcoholic media, followed with reduction. 4‐Amino‐N‐methyl and ethyl glycinate‐1,8‐naphthalimide were obtained. These products were diazotized and coupled with appropriate aromatic amines to give bluish‐red or violet dyestuffs. All intermediates and dyestuffs were purified and characterized by ¹H‐NMR, FTIR, DSC, UV‐VIS and Elemental Analysis. Dispersion of dyestuffs was prepared in water and applied to polyester fabrics. The dyed fabrics showed that four of the synthesized dyestuffs were suitable for coloring polyester fibers, producing deep bluish red with very good build up properties.     

Raman spectral study of the constitution and equilibria of nitric acid and d-nitric acid

From relative integrated intensity measurements of the symmetric stretching vibration of nitrate ion in nitric acid solutions (both HNO ₃ /H ₂ O and DNO ₃ /D ₂ O), the mass law concentration quotients, Q were obtained as functions of concentration. By extrapolation the limiting dissociation constants were estimated to be 24.4 and 15 respectively at 25°C. It is shown that this constant refers to a process in which the ion pair H ₃ O⁺ NO ₃ ^– is in equilibrium with the dispersed, solvated H ₃ O⁺ and NO ₃ ^– ions.     

Characterization and properties of the copper(II/I) complexes of macrocyclic hexathiaether ligand [21]aneS6

The copper(II/I) complexes of hexathiaether macrocyclic ligand, 1,4,8,11,15,18-hexathiacyclohenicosane ([21]aneS₆), were synthesized, and characterized by electrochemical and spectroscopic techniques. Cyclic voltammetric studies indicate that Cu([21]aneS₆)^2+/+ forms a reversible one-electron redox couple. The electrochemical potential obtained for Cu([21]aneS₆)^2+/+ (E^f = 0.89 V, against SHE) was found to be the highest potential reported to date for a Cu^2+/+ macrocyclic system in aqueous solution. By employing the Nernst equation, we can infer that the practical upper limit for formal potential of Cu(II/I)L systems maybe close to this high value. Stability constant data obtained for these complexes indicate that Cu([21]aneS₆)⁺is 12 orders of magnitude greater in stability than that of Cu([21]aneS₆)²⁺ indicating the favorable nature of this large macrocyclic ligand towards formation of Cu(I) complexes over Cu(II) complexes. Crystal structure of Cu([21]aneS₆)⁺ ( Fig. 2) shows that four sulfurs adjacent to one another are coordinated to Cu⁺ ion in this complex. Bond angles and distances calculated for the crystal indicate that it is a distorted tetrahedron, a geometry commonly encountered by Cu(I) complexes. This is the first report of synthesis and characterization of a metal coordinated [21]aneS₆ complex.     

Cationic Heteroconjugation Constants in the OHN+ and NHO+ Systems in Propylene Carbonate: Dependence on Difference in Basicity

Cationic heteroconjugation equilibria of more than ninety systems consisting of substituted pyridines, their N-oxides, and trimethylamine N-oxide, i. e., in systems with mixed hydrogen bridges of type OHN⁺ (NHO⁺) were studied in propylene carbonate. Both experimental systems without proton transfer, BH⁺/B₁, and those with proton transfer, B₁H⁺/B, were explored. The stability of the mixed hydrogen bridges, OHN⁺ (NHO⁺), is compared with that of the OHC⁺-type bridges. The influence of the difference in basicity of the conjugate base of the proton donor and the proton acceptor on the presence of the proton transfer equilibria, and, consequently, the possibility of determination of the cationic heteroconjugation constant values is discussed.     

NMR and potentiometric determination of the high pK values and protonation sequence of dipyridino-hexaaza-28-crown-8 and its interactions with selenate,sulfate and nitrate ions in aqueous solution

The aqueous protonation and anion-binding SeO ₂ ^–/4 SO _2– ⁴ , and NO _– ³ ) constants of the macrocyclic polyamine ligand, dipyridino-hexaaza-28-crown-8(L), were measured in 0.1M KCl using a potentiometric titration technique. The protonation sequence of the aza groups of L was studied in D₂O from the chemical shifts of the nonlabile protons so as to find the charge distribution geometry as a function of pD. The study indicates that in 0.1M KC1 fully protonated L forms stable l: 1 complexes with SeO _2– ⁴ (logK=3.68) and SO _2– ⁴ (logK=3.55), but not with NO _– ³ (logK < l.5). All of the amine pK values were above 6.3, thus allowing the use of the protonated form of this ligand over a wide pH range.     

Kerr constants and dipole moments of aminobenzoic acids in dioxane

Aminobenzoic acids in dioxane have been investigated by dipole moment and Kerr effect methods.m-Aminobenzoic acid exists in a solution mainly (60 %) in thesyn-form. Inp-aminobenzoic acid, conjugation flattens the pyramidal configuration of the nitrogen atom, which is even more flattened ino-aminobenzoic acid owing to an intramolecular hydrogen bond.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 859–861, May, 1994.     

Phosphorus-containing podands

A number of monopodands havingo-diphenylphosphinyl terminal groups were synthesized by alkylating sodium derivatives of oligoethylene glycols witho-(bromomethyl)phenyldiphenylphosphine. The stability constants of the complexes of these ligands with alkali metal cations at 25 °C were determined conductometrically in a THF—chloroform solution (41, v/v). The complexing ability of monopodands with respect to the cations studied increases monotonically as the number of electron-donating sites increases (from 3 to 8) for all of the cations except Li⁺ and, to some extent, Na⁺. In the case of Li⁺ a smooth decrease in the stability of the complexes is observed. The monopodands obtained in this work differ drastically in this regard from their structural isomers, bis[o-(diphenylphosphinylmethyl)phenyl] ethers of oligoethylene glycols, which had been studied previously.For part 10, see ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 952–956, May, 1993.     

Evaluation of dissociation constants of ammonium ion in aqueous lithium perchlorate and lithium chloride-sodium chloride mixed solutions

The Pitzer approach has been applied to the evaluation of dissociation constants of ammonium ion in lithium perchlorate and lithium chloride-sodium chloride mixed solutions at 25°C. The calculated values showed good agreement with the observed values, provided all the higher-order interaction terms ('s and 's) concerned were introduced. The unknown (NH₄LiClO₄) value was determined from the isopiestic measurements of NH₄ClO₄–LiClO₄ mixed solutions. Parameters in the Pitzer formalism for ammonia-ion interactions involved in LiCl and NaCl media were determined by use of the activity coefficients of ammonia measured in LiCl–NaCl mixed solutions by a transpiration method.