15N, 31P,and 13C NMR Spectroscopy of N-Arylsulfonyl-and N-Arylcarbonyl-P,P,P-triphenylphospha-λ-Azenes. Substituent Effects and Electronic Structure

Abstract

The ¹⁵N, ³¹P and ³¹C NMR spectra of several series of phospha-λ⁵-azenes are reported. For the N-arylsulfonyl-P,P,P-triphenylphospha-δ⁵-azene series (R-C₆H₄N-SO₂-PPh₃), the ³¹P chemical shifts, various ¹³C chemical shifts and ¹J_PN were observed to correlate linearly with the Hammett σ constants. Interestingly, the ¹⁵N chemical shifts did not correlate acceptably with any σ or with the Taft dual substituent parameter equation, and 1J_PC was invariant with substituent. For the N-arylcarbonyl-P,P,P-triphenylphospha-λ⁵-azene series (R-C₆H₄-CO-N=PPh₃), δ_31P and various δ_13C's were observed to linearly correlate with the δ constants, while δ_15N, ¹J_PN and ¹J_PC correlated with both the σ and σ constants. For the N-phenyl-P,P,P-triarylphospha-λ⁵-azene series [Ph-N=P(C₆H₄-R)₃] the best correlations were observed between ³¹P, ¹⁵N and several ¹³C chemical shifts and the σ constants.     

Application of Multinuclear MAS NMR for the in situ Monitoring of Hydrothermal Synthesis of Zeolites

In situ MAS NMR studies on the monitoring of hydrothermal synthesis of zeolites are reviewed. The first part of the review contains information on the experimental techniques used for the in situ NMR studies in static and MAS conditions. In the second part, the main capabilities of the in situ ¹H, ¹¹B, ¹³C, ¹⁴N, ¹⁹F, ²³Na, ²⁷Al, ²⁹Si and ³¹P MAS NMR for the elucidation of the mechanism of hydrothermal synthesis of zeolites are examined and the data on NMR lines identification are summarized. In the last part the main application areas of the techniques are considered and illustrated with examples taken from the mechanistic studies of zeolites A, X, MFI and BEA synthesis. A cross-reference index between the materials studied, the experimental approaches used, the mechanistic information obtained, and the corresponding literature sources is established.     

A 13C, 31P and 15N NMR investigation of some 2-substituted-N-phenyl-P,P,P-triphenylphospha-λ5-azenes

¹³C, ³¹P and ¹⁵N NMR data are reported for seven 2-substituted-N-phenyl-P,P,P-triphenylphospha-λ⁵-azenes taken at room temperature in acetone-d₆ solutions. Ortho substituents significantly influence ¹³C, ³¹P, ¹⁵N chemical shifts and ¹J(³¹P¹⁵N), ³J(³¹P¹³C) Couplings.     

Fluorometric and NMR Studies of the Naproxen–Cyclodextrin Inclusion Complexes in Aqueous Solutions

Inclusion complexation processesinvolving four cyclodextrins and naproxen have beenstudied for the protonated and unprotonated forms ofthe guest molecule. The association constants havebeen evaluated from changes in the fluorescenceintensity of naproxen following addition of acyclodextrin to an aqueous naproxen solution. ¹HNMR NOESY and ROESY spectra have shown that twoorientations of the guest molecule relative to-cyclodextrin are possible.     

NMR Studies on the Subacute Biochemical Effects of Aristolochic Acid on Rat Serum

The subacute effect of aristolochic acid （AA） on rat serum was studied by NMR method. The biochemical effects induced by AA were characterized by an increase in the amounts of creatinine, trimethylamine N-oxide, acetoacetate, acetate and 3-D-hydroxybutyrate and lactate in serum from ^1H NMR spectra. Principal component analysis was used for further comparing the similarities of ^1H NMR spectral profiles of serum from rats treated with AA and model toxins.     

Structural and bonding aspects of molybdenum tricarbonyl complexes of 2,4,6-tritertiarybutyl-1,3,5-triphosphabenzene,P3C3But3 and some λ3,λ3,λ5- and λ3,λ5,λ5-alkylated derivatives

The molecular structure of the previously reported compound [Mo(CO)₃(η⁶-P₃C₃Bu^t₃)] has been determined by a single-crystal X-ray diffraction study. Syntheses and molecular structures are also described for the structurally related compounds [Mo(CO)₃(η⁵-P₃C₃Bu^t₃)(Me)(Buⁿ)], [Mo(CO)₃(η⁵-P₃C₃Bu^t₃)(H)(Buⁿ)] and [Mo(CO)₃(η⁴-P₃C₃Bu^t₃(Me)(Buⁿ)(H)(O)Li(THF)₃]. Density functional calculations at the B3LYP/cc-pVDZ(-PP) and BP86/cc-pVDZ(-PP) levels have been carried out on the above complexes and the nature of the bonding between the different rings and molybdenum is discussed. ³¹P NMR spectroscopic evidence is presented for the existence of the novel complex [Mo(CO)₃(η⁶-P₃C₃Bu^t₃)PtCl₂(PEt₃)] in which the triphosphabenzene ring acts as an overall 8-electron donor to the two metal centres.     

Multinuclear NMR structural study of novel γ-iminophosphonate and phosphine oxide derivatives

Journal of Structural Chemistry - We report for the first time the synthesis of γ-iminophosphonates and phosphine oxides from the acid-catalysed reaction of primary amines with...     

Studies of the Effects of Alkali Metal Oxides Promoter on the Oxidative Methylation of Toluene with Methane over KY Zeolite Catalysts

Methane is the most abundant component of natural gas. The direct conversion of methane into chemical feedstock or transportable liquid fuel is an attractive process. In addition to oxidative coupling of methane, oxidative methylation of toluene with methane to styrene and ethylbenzene which has been investigated by Khcheyan et al.1, provides another possibility of methane utilization. Recently, several research groups have employed some metal oxides for the oxidative methylation of toluene w…     

Conductivity Studies of Glasses in the System WO3−P2O5

Russian Journal of Applied Chemistry - Quenching method was used to obtain glasses in the system xWO3-(100-x)P2O5 (x = 70, 75, 80, 82 mol %). The electrical conductivity of the compositions was...     

^31P NMR Studies on the Ligand Dissociation of Trinuclear Molybde-num Cluster Compounds

A series of carboxylate-substituted trinudear molybdenum dus-ter compounds formulated as Mo3S4(DTP)3(RCO2)(L), where RffiH, CH3, C2H5, CH2Cl, CCl3, R^1C6H4(R^1 is the group on the benzene ring of aromatic carboxylate ), L=pyridine,CH3CN, DMF, have been synthesized by the ligand substitu-tion reaction. The dissociation of the loosely-coordinated ligand L from the cluster core was studied by ^31p NMR. The dissocia-tion process of L is related to the solvent, temperature, and acidity of carboxylate groups, so as to affect the solution struc-ture and reactive properties of the duster. The long-distance in-teraction between ligands RCO2 and L is transported by Mo3S4 core.     

Multinuclear NMR study of lanthanide(Ⅲ)complexes of 1,2-PDTA in aqueous solution

The complexation oflanthanide(Ⅲ) cations with 1,2-propanediaminetetraacetate (1,2-PDTA)in aqueous solution has been investigated by ~(23)Na,~(35)Cl,~2H and ~(17)O NMR shift measurements.It hasbeen shown that the contact shifts are dominant for ~(17)O,~(35)Cl and ~2H (only for the heavier lanthanideseries) and the pseudocontact shifts are dominant for ~(23)Na.It is suggested that the 1,2-PDTA ligandis bound pentadentately via the two nitrogens and the three carboxylates for the lighter lanthanidecomplexes,hexdentately via the two nitrogens and the four carboxylates for the heavier ones.Thenumbers of the water coordinated were determined.The small amount of chloride anion in innercoordination sphere was observed.     

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).     

10-Oxo-10H-5λ,10λ-thianthren-5-ylideneamine as a probe for stereochemistry in the formation and amination of fluoro-λ-sulfanenitriles

The fluorination of 10-oxo-10H-5λ⁴,10λ⁴-thianthren-5-ylideneamine (2) with Selectfluor™ affords 5-fluoro-10-oxo-5,10-dihydro-5λ⁶,10λ⁴-thianthren-5-nitrile (4). The amination of 4 with morpholine gives 5-morpholino-10-oxo-5,10-dihydro-5λ⁶,10λ⁴-thianthren-5-nitrile (5). The stereochemical course of both reactions has been studied, while the configurations of their products, cis-isomer 4 and trans-5-morpholino-10-oxo-5,10-dihydro-5λ⁶,10λ⁴-thianthren-5-nitrile (trans-5) are elucidated by the use of X-ray crystallographic analyses.     

Equilibrium and NMR Studies of Noncovalent Interactions in Binary Systems: Uridine,Adenosine, Cytidine and Thymidine,and Adenosine (or Cytidine) 5′-Monophosphate in Aqueous Solution

The molecular complex formation reactions of uridine (Urd) with adenosine (Ado), cytidine (Cyd), thymidine (Thd), adenosine 5-monophosphate (AMP) and cytidine 5-monophosphate (CMP) have been studied at 20°C. It was found that the main positive noncovalent centers of ion–dipole and dipole–dipole type interactions are the protonated N(3) atoms of Urd, whereas the negative centers are the endocyclic atoms of the bases characterized by high electron density from the second molecule involved in the reaction. Moreover, NMR results indicate the occurrence of stacking in the complex (Urd)H(Cyd), whereas in the complex, (Urd)H₂(Thd), it is the only type of interaction. Deprotonation of the latter species brings about a change in the character of the reaction and ion–dipole interactions have been detected in the adduct, (Urd)H(Thd). Interestingly, no involvement of the phosphate groups in the formation of AMP and CMP adducts has been evidenced and the main centers of the reactions were found to be the N(7)and N(1) atoms of AMP, or the N(3) atoms of CMP and Urd. Moreover, in the Urd/CMP system the NMR results suggest stacking-type interactions.     

Thermodynamic and 13C NMR Studies of the Inclusion Complexes of α- and β-Cyclodextrins with Cyano- and Nitrophenols in Aqueous Solution

Equilibrium constants for the formation of 1 : 1 inclusioncomplexes of -cyclodextrin (-CD) with neutral and anionic phenol derivatives (3- and 4-cyanophenols and 3- and 4-nitrophenols) have been evaluated at 5, 12, 25, and 35 °C by means of spectrophotometry. Similarly, the equilibrium constants have been determined for the inclusion complexes of-cyclodextrin (-CD) with the phenols. Enthalpy and entropy changes for the formationof the inclusion complexes have been estimated from the temperature dependences of theequilibrium constants. With -CD, the enthalpy andentropy changes for the anionic species have been found to be more negative than those for the neutral ones, except for 4-cyanophenol, suggesting that the inclusion complexes of the anionic species are more rigid than those of the neutral species. From analyses of chemical shift differences in ¹³C NMR spectra of 3- and 4-cyanophenolsand 3- and 4-nitrophenols in aqueous solutions with and without CDs, a nitro ora cyano group has been found to be first bound to the - and -CD cavities.     

Studies of the dissociation and the protonation of TB-chlorosulphophenol

The dissociation constant of each step for TB-chlorosulphophenol has been determined by potentiometric method, and the thermodynamic constants, △G°, △H° and △S°, of the dissociation process have been calculated. The protonation constants were measured by the spectrophotometric method. The pH values of various forms of anions of the chromogenic reagent at their concentrations were also calculated.     

Studies on the Structure, Properties of Ferroaluminophosphate Molecular Sieve (FAPO-5) and Chemical State of Iron in the FAPO-5 Molecular Sieve

The pure Ferroaluminophosphate molecular sieve(FAPO-5) was synthesized by hydrothermal crystallization. The crystal structure of FAPO-5 was studied via XRD, electron probe energy dispersion analysis, Mossbauer spectroscopy, EPR, XPS and IR, the parameters of unit cell and chemical composition of FAPO-5 were determined. The result has that the structure of FAPO-5 is AlPO -5 type and Fe2+ Fe3+ are incorporated into the framework of FAPO-5 molecular sieve. In addition, the chemical state of iron in FAPO-5 molecular sieve were studied and the adsorption properties, surface acidity and thermal stability were also investigated.     

Studies on the Effects of Epimedium Extract on Erythrocytes

Epimedium, one of representatives of traditional Chinese herb, is mainly composed of flavones and polysaccharide. It is famous for its antioxidant, antineoplastic and antiaging activities and has been widely used in the field of invigorating kidney and st…