IR Study of p–π Conjugation in 2-Substituted 4-Methylene-1,3-dioxolanes and 4-Methyl-1,3-dioxoles

Selected group frequencies of the IR spectra of a number of 2-substituted 4-methylene-1,3-dioxolanes (a) and their endocyclic isomers, 2-substituted 4-methyl-1,3-dioxoles (b), have been studied to establish their usefulness as a measure of the strength of p– conjugation in the O—C=C moieties of the title compounds. In the exo compounds (a), the C=C stretching frequencies C=C and the in-phase, out-of-plane bending (wagging) frequencies CH₂ w of the =CH₂ group were found to be linearly related, besides to each other, also to the electron-donating character of the substituents and the ¹³C NMR chemical shift of the C atom of the exocyclic CH₂ group. This suggests that the two IR group frequencies of the exo isomers are linearly related to the strength of p– conjugation in the O—C=C moiety. The C=C stretching absorption of the exo compounds in the 1600–1700 cm^–1 region appeared as a doublet, shown to arise from Fermi resonance of the C=C fundamental with the CH₂ w overtone. The C=C frequencies of the endo compounds support some previous findings of an unexpected strength of p– conjugation in the 2-alkoxy derivatives. Finally, DFT calculations at the B3LYP/6-31G* level of theory are shown to give accurate predictions of the effect of 2-substituents on the group frequencies.     

1H and 13C NMR Spectroscopy of Stereoisomeric 2′-deoxy-C-Nucleosides

Eleven furanosyl 2′-deoxy-C-nucleosides with β-D-erythro, α-D-erythro and β-D-threo configurations have Been studied by IH and ¹³C NMR spectroscopy recorded in CDC1₃ and/or DMSO-d ₆. Results obtained indicate that each of the three stereoisomeric configurations studied are identifiable by ¹H and ¹³C NMR spectroscopy using a combination of coupling constant and chemical shift criteria.     

1H and 13C NMR characteristics of β-blockers

The β-blockers are important drugs and decades of clinical experience proved their high medical status. However, to the best of our knowledge, there is no complete assignment of (1)H and (13)C NMR resonances of popular representatives: acebutolol, alpenolol, pindolol, timolol and propranolol and the published NMR data on carvedilol and atenolol are incorrect. Therefore, (1)H and (13)C NMR spectroscopy was applied for the characterization of a series of β-adrenolytics: carvedilol (1), pindolol (2), alprenolol (3), acebutolol (4), atenolol (5), propranolol (6) and timolol (7). Two-dimensional NMR experiments (COSY, HMQC, HMBC, NOESY) allowed the unequivocal assignment of (1)H and (13)C spectra for solution (DMSO-d(6) ). Salts and bases can be easily distinguished based on (13)C chemical shifts which are within 65.0-65.5 ppm (OC2) and 46.9-47.0 (NC3) for hydrochlorides and larger, ca. 68.4 ppm (OC2) and 50.3-52.6 (NC3) for bases. NMR data of 1-7 should be included in pharmacopoeias.     

β-diketone interactions: Part 4. The structures and properties of 1,3-diphenyl-2-methylpropane-1,3-dione,C16H14O2, and 1,3-diphenyl-2-(4-methoxyphenyl)propane-1,3-dione,C22H18O3

The X-ray crystal structures of 1,3-diphenyl-2-methylpropane-1,3-dione and 1,3-diphenyl-2-(4-methoxyphenyl)propane-1,3-dione show them both to adopt cis-diketo (Z,Z) conformations with carbonyl—carbonyl dihedral angles of 89.0(3)° (2-methyl derivative), and 85.5(4)° and 77.7(4)° for the two molecules in the asymmetric unit of the 2-(4-methoxyphenyl) derivative. These are the first acyclic β-diketones with an α-hydrogen to be reported which do not have an enol configuration in the solid state.     

Studies on the vibrational spectra of perhydrates—I. Spectra of normal and isotopically substituted (2H, 13C) alkali metal oxalate perhydrates,MI2C2O4·H2O2

The Raman and i.r. spectra of solid Na₂C₂O₄·H₂O₂, K₂C₂O₄·H₂O₂ and their ¹³C and ²H substituted analogues have been measured (400–4000 cm⁻¹), and modes due to oxalate and hydrogen-bonded H₂O₂ assigned. Vibrational spectra are also reported for M^I₂C₂O₄·H₂O₂ (M = Li, Rb, Cs). The use of such spectra in distinguishing between skewed and trans-planar hydrogen-bonded H₂O₂ is discussed. Vibrational spectra of the free oxalate ion (both normal and ¹³C-substituted) in aqueous solution have also been measured.     

Synthesis,GC-EIMS,~1H NMR,~(13)C NMR,Mechanistic and Thermal Studies of o-Xylylene-α,α'-bis (triphenylphosphinebromide)

Organophosphorous compounds containing phosphorus as an integral part have been widely used in industry, organic synthesis and optoelectronics. o-Xylylene-α,α'-bis(triphenylphosphinebromide)(OXBTPPB) is a facile reagent to convert o-quinones(e.g., 9,10-phenanthrenequinone) into polycyclic aromatic hydrocarbons(PAHs). Herein lies an improved synthetic route to OXBTPPB. The resultant was carefully characterized with GC-EIMS, 1H NMR, 13C NMR, spectroscopic techniques. The EIMS shows characteristic peaks at m/z...     

Synthesis and structure of nalidixium tetrachloroantimonate monohydrate, (C12H13N2O3)SbCl4 · H2O

Nalidixium tetrachloroantimonate monohydrate, (C₁₂H₁₃N₂O₃)SbCl₄ · H₂O, has been synthesized and its crystal structure has been determined. The structure is built of the [Sb₂Cl₈]^2? anions, C₁₂H₁₃N₂O ₃ ⁺ nalidixium cations, and H₂O molecules joint by hydrogen bonds and π-π-and Cl?Cl interactions. The [Sb₂Cl₈]^2? anion is a dimer of the SbCl₅ E distorted octahedra sharing common Cl?Cl edge (E is the lone electron pair). The Sb polyhedra contain two short Sb-Cl bonds (2.387 and 2.395 Å), one bond of a medium length (2.508 Å), and two long bridging bonds (2.745 and 3.054 Å).     

Cooperativity in alkane-1,2- and 1,3-polyols: NMR,QTAIM, and IQA study of O─H…OH and C─H…OH bonding interactions

Proton nuclear magnetic resonance chemical shifts and atom–atom interaction energies for alkanepolyols with 1,2-diol and 1,3-diol repeat units, and for their 1:1 pyridine complexes, are computed by density functional theory calculations. In the 1,3-polyols, based on a tG'Gg' repeat unit, the only important intramolecular hydrogen bonding interactions are O─H^…OH. By quantum theory of atoms in molecules analysis of the electron density, unstable bond and ring critical points are found for such interactions in 1,2-polyols with tG'g repeat units, from butane-1,2,3,4-tetrol onwards and in their pyridine complexes from propane-1,2,3-triol onwards. Several features (OH proton shifts and charges, and interaction energies computed by the interacting quantum atoms approach) are used to monitor the dependence of cooperativity on chain length: This is much less regular in 1,2-polyols than in 1,3-polyols and by most criteria has a higher damping factor. Well defined C─H^…OH interactions are found in butane-1,2,3,4-tetrol and higher members of the 1,2-polyol series, as well as in their pyridine complexes: There is no evidence for cooperativity with O─H^…OH bonding. For the 1,2-polyols, there is a tenuous empirical relationship between the existence of a bond critical point for O─H^…OH hydrogen bonding and the interaction energies of competing exchange channels, but the primary/secondary ratio is always less than unity.     

Reactivity, 31P, 13C, 1H NMR and IR Studies of Δ5-3-Dimethylamino-3-Oxo-1,2,3- Diazaphospholines

Abstract

In precedent work research (1)(2) we have reported a new synthesis method of the Δ⁵-3- dimethylamino-3-oxo-l,2,3 diazaphospholine derivatives (D_i). In this present work, we have to detail the reactivity and the structure of those heterocycles by N.M.R. (³¹P, ¹³C, ¹H) and I.R. In Infra-Red spectroscopy, we show the existence of the intermolecular hydrogen bond of some compounds. The spectrum(³¹P, ¹³C, ¹H) and I.R. was reported of (D_i).     

Synthesis and Biological Activity of O,O′-Dialkyl 5-Aryl-1-Hydroxy-3-Methyl-2E,4E-Pentadienylphosphonates

A series of unsaturated f -hydroxy phosphonates were synthesized by the addition reactions of dialkyl phosphites with 5-aryl-3-methyl-2E, 4E-pentadienaldehydes. The structures of all new compounds have been confirmed by 1 H NMR, 31 P NMR, and IR spectroscopy and by elemental analysis or MS. The bioassays showed that some of these compounds exhibit certain inhibitory activity on the elongation of wheat coleoptile.     

Synthesis,Spectroscopic Properties and Crystal Structure of (C4N2H12)2Zr(C2O4)4·H2O

The title compound (C4N2H12)2Zr(C2O4)4·H2O 1 was synthesized by the reaction of ZrOCl2·8H2O, H2C2O4·2H2O and piperazinium in aqueous solution. Single-crystal X-ray analysis has revealed that compound 1 (C16H26N4O17Zr, Mr = 637.63) crystallizes in the monoclinic system, space group P21/c with a = 9.0425(3), b = 13.3844(3), c = 19.1191(5)A, β = 98.365(1)o, V = 2289.34(11) A3, Z = 4, Dc = 1.850 g/cm3, F(000) = 1304, μ = 0.577 mm-1, the final R = 0.0240 and wR = 0.0628 for 4386 observed reflections with I > 2σ(I). X-ray crystal-structure analysis suggests that compound 1 consists of [Zr(C2O4)4]4- anion and two protonated piperazinium cations. The anions are linked through hydrogen bonds of piperazinium. FT-IR and Raman spectra clearly show the existence of oxalate groups in the crystal lattice.     

Synthesis, Crystal Structure and Properties of [Co(1,3- bdoaH)2·4H2O] ·4H2O with Benzene-1,3-dioxyacetate Ligand

The cobalt(II) complex C20H34O20Co has been synthesized and characterized by elemental analysis, IR, TG and single-crystal X-ray diffraction. The crystal belongs to triclinic, space group P with a = 5.1374(10), b = 10.519(2), c = 12.913(3) (A), α = 86.89(3), β = 79.94(3), γ = 86.74(3)o, V = 685.3(3) (A)3, Z = 1, Mr = 653.40, Dc = 1.583 g/cm3, μ = 0.717 mm-1, F(000) = 341, the final R = 0.0657 and wR = 0.1141 for 1900 observed reflections with I > 2σ(I). The cobalt ion is six-coordinated by two O atoms of different 1,3-bdoaH- ligands and four water molecules, residing in an octahedral environment. The intermolecular hydrogen bonds form a 3-D supramolecular network structure.     

13C NMR spectra of 17-substituted epimeric 17α and 17β-ethynylandrostenes and their hexacarbonyldicobalt complexes

¹³C NMR spectra of epimeric 17-R-substituted 17-ethynylandrostenes (R = H, OH, OAc, OMe, NCS) and 17-R-substituted 17-ethynylandrostenes (R = H, OH, OAc, OMe), and their hexacarbonyldicobalt complexes, as well as of ¹⁶-17-ethynylandrostenes and their hexacarbonyldicobalt complexes have been studied. Stereochemical dependence of C(12), C(14), C(18), C(20) and C(21) chemical shifts on the configuration of the substituents at C(17) has been demonstrated. The effect of Co-complexation on the spectral characteristics of Co-coordinated 17-ethynylandrostenes in both Stereochemical series has been investigated.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 212–216, January, 1993.     

Deuterium quantification through deuterium-induced remote 1H and 13C NMR shifts

Partial labeling by deuterium may be quantified through simple integrations of those (1)H (200 or 400?MHz) and (13)C (100.6?MHz) NMR resonances that are split into pairs by chemical shifts (n)Δ = δ(deuterated) - δ(nondeuterated) as induced by deuterium across n>2 chemical bonds. The relative intensities of the two components of a pair are shown to be influenced to practically equal degrees by relaxation effects, so that a deuterium fraction may be determined from (1)H and (13)C integral pairs at more remote molecular positions under the routine conditions of fast accumulative spectral acquisition.     

Syntheses and Structures of Two New Coordination Polymers:[Cu(C14H9O4)(C14H10O4)(C12H12N2)2] and [Ag(C14H9O4)(C13H14N2)]·0.5 H2O

Under hydrothermal conditions, two new ribbon-like structures, [Cu(C14H9O4)-analysis revealed that these structures were constructed by mixed ligands. The coordination polymer forms the basic architecture while the weak interactions extend the framework into a secondary structure. The whole structures of them are governed by collaboration of the strong and weak interactions. Compound 1 crystallizes in monoclinic, space group C2/c with a = 17.0485(3), b =1 1.0558(3), c = 22.7623(4) A, β = 102.465(1)°, V = 4189.2(2) A3, Z = 4, Mr = 915.44, Dc = 1.451g/mL, F(000) = 1900 andμ(MoKα) = 0.587 cm-1. The final R and wR are 0.0030 and 0.1022,respectively for 3037 observed reflections with I ＞ 2σ(I). Compound 2 crystallizes in monoclinic,space group P21/c with a = 11.5963(4), b = 11.7004(5), c = 17.1254(5) A,β = 95.620(1)°, V =2312.4(1) A3, Z = 4, Mr = 556.35, Dc = 1.598 g/mL, F(000) = 1132 andμ(MoKα) = 0.912 cm-1The final R and wR are 0.0431 and 0.1050, respectively for 2629 observed reflections with I ＞ 2σ(I).     

1H, 13C and 29Si NMR study of α- and β-silylstyrenes and their adducts with dichlorocarbene

¹H, ¹³C and ²⁹Si NMR spectra for the α- and β-silylstyrenes (E)-PhCHCHSiR₃ (I) and PhC(SiR₃)CH₂ (II) (R = Cl, Me, Ph), and those for some dichlorocarbene adducts of I and II (R = Me, Ph), were examined. From the ¹³C NMR data, the phenyl substituent in the molecules I and II enhances the electronic effects of the organosilicon substituent at Cα, and weakens these effects on the C_α resonance. The degree to which polarization of the vinyl CC bond is polarized increases with increased electron-withdrawing properties of substituent R in the SiR₃ group in compounds I and II, and correlates with the reduced reactivity of the bond toward electrophilic dichlorocarbene. Several long-range coupling constants (CC) in the molecules I, II and in their adducts with :CCl₂ were measured. The estimated CC is a useful aid for the study of electronic effects in organosilicon compounds.     

Synthesis and Crystal Structure of (C6N3H18)2Ti4O4(C2O4)7·4H2O

The title compound (C6N3H18)2Ti4O4(C2O4)7(4H2O 1 (C13H22N3O18Ti2, Mr = 604.14) was synthesized by the reaction of Ti(SO4)2, H2C2O4(2H2O and N-(2-ammonioethyl)- piperazinium (AEPP) in aqueous solution. The single-crystal X-ray analysis has revealed that 1 crystallizes in the triclinic system, space group Pī with a = 9.1437(6), b = 11.4991(10), c = 11.6975(8)A, α = 96.2915(18), β = 107.998(3), γ = 104.276(4)°, V = 1110.35(14)A3, Z = 2, Dc = 1.807 g/cm3, F(000) = 618, μ = 0.815 mm－1, the final R = 0.0463 and wR = 0.1264 for 3718 observed reflections with I > 2σ(I). X-ray crystal-structure analysis suggests that compound 1 consists of [Ti4O4(C2O4)7]6－ anion and two protonated N-(2-ammonioethyl)piperazinium cations. The anions are linked into an infinite chain through Ti4O4(C2O4)8 by sharing the oxalates as bridging ligands.