G. V. Ratovskii

Spectral manifestations of intramolecular interactions in acid chlorides of unsaturated phosphorus acids

The UV absorption spectra of acid dichlorides of aryl phosphonic and phosphinic acids in the 185–340 nm region were investigated. Hypothetical conclusions are made concerning the nature of the electronic transitions in phosphorus-containing benzenes. The interaction of phosphorus-containing group with a π-electron system of the aromatic radical is characterized on the basis of the data obtained. The role of vacant orbitals of phosphorus and chlorine atom, unshared pair pIII, and pπ−dπ bond of the phosphoryl group in the investigated effects is examined.

Donor-acceptor complexes of vinyl aryl ethers with maleic anhydride

1. Nuclear magnetic resonance and infrared spectroscopies have been used to characterize the donor-acceptor complexes formed between vinyl aryl ethers and maleic anhydride; the values obtained for the equilibrium constant and the enthalpies and entropies of complexing suggest that there is a slight increase in the donor activity of the vinyl ether of phenol when a methyl group is introduced into its benzene ring. 2. Donor-acceptor interaction of the maleic anhydride with the vinyl aryl ethers leads to the formation ofπ complexes through weak charge transfer from the highest occupied orbital of the ether to the lowest vacant orbital of the anhydride. Quantum-chemical calculations and measurements of the chemical shifts on the13C and1H nuclei of the vinyl ethers under action from the MA indicate that the donor HOMO embraces the unshared electron pair of the oxygen and the π electrons of the double bond and the benzene ring.

X-ray fluorescence spectroscopy study of the charge state of hetero atoms in organic compounds of row III elements. 9. Compounds containing P=S and P-S fragments

The dependences of the shift of the Kα line of sulfur on the effective charge on the S atom, calculated by the CNDO/S method, are decomposed into two linear dependences: one for a compound of thione sulfur, the other for the rest of sulfur-containing systems. The dependences of the shift of the Kα line of P on the effective charge on the P atom, calculated by the CNDO/S method, are also decomposed into two linear dependences; one for compounds of three-coordinate P, the other for compounds of P with coordination number >3. In thiophosphoryl compounds, the electron density on the S atom varies symbatically with that for the P atom. In systems containing the P-S bond, the magnitudes of the effective charge on the S atom remain virtually constant.

Complex formation between maleic anhydride and the vinyl ethers of phenol and para-methoxyphenol

Conclusions1.The mechanism of the formation of the π complexes of maleic anhydride with vinyl aryl ethers was studied by IR and UV spectroscopy and quantum chemistry.2.The donor center during the complexation of maleic anhydride with vinyl phenyl ether in the case of the nonplanar conformation of the ether is the vinyloxy group. This leads to an increase in its reactivity during copolymerization. In the case of the planar conformation of the vinyl phenyl ether the main donor center is the phenoxy group. This gives rise to a significant decrease in the reactivity of the double bond in the maleic anhydride. On the whole a mixed mechanism of formation of the alternating copolymers is observed.3.The complexation of maleic anhydride with p-methoxyphenyl vinyl ether in both conformations takes place with the participation of the aromatic fragment. This leads to a decrease in the reactivity of the monomers and to a consecutive mechanism of formation of the alternating copolymers.

Investigation of the charge state of heteroatoms in organic compounds of third-row elements by X-ray fluorescence spectroscopy. 4. Investigation of the electronic structure of the sulfonyl group in β-substituted vinyl sulfones

Conclusions1.The values of the charges on the S atom and the frequencies and intensities of the stretching vibrations of the sulfonyl group in β-substituted vinyl sulfones have been determined.2.In sulfonyl-substituted vinyl sulfides, ethers, and amines the mesomeric interaction of the sulfonyl and β-substituted vinyl groups results in decreases in the multiplicity and increases in the polarity of theS...O bonds along the series SR < OR < NR2, while the charge on the S atom remains practically unchanged.

Spectral effects of intramolecular interactions in the chloranhydrides of unsaturated phosphorus acids

Measurements have been made of the integral Raman line strength of unsaturated phosphorus acids; it is concluded that the phosphorus-bearing group interacts with theπ-electron system of the aromatic radical in the excited state. It is found that the -PCl2, -P(O)Cl2 and -P(S) · Cl2 will show acceptor behavior in the conjugated system when interacting with donor substituents. The role of the vacant orbitals of the chlorine attached to the phosphorus is discussed.

Spectral manifestations of intramolecular interactions in acid chlorides of unsaturated acids of phosphorus

The mutual effect of atomic groups in acid chlorides of threeand four-coordination phosphorus was investigated by the nuclear quadrupole resonance of Cl35 (NQR Cl35) and Raman spectroscopy methods. On the basis of the NQR data it is suggested that in the ground state the interaction of unshared pairs of chlorine with the d orbitals of phosphorus is displayed weakly and the interaction of the indicated atoms is accomplished predominantly by an inductive mechanism. The integral intensities of the Raman lines of vibrations of the P-Cl and P=Cl bonds were measured. The Raman scattering data and the results of quantummechanical calculations by the molecular orbital method indicate some additional multiplicity of the P-Cl bond.

Investigations of vinyl esters of the furan series: X. Synthesis and spectral investigation of vinyl esters of furan-2-carboxylic acids

The vinyl esters of trans-β-(2-furyl) acrylic acid, furan-2-carboxylic acid, 5-bromofuran2-carboxylic acid, and 5-nitrofuran-2-carboxylic acid were synthesized by the reaction of the corresponding acids with acetylene and vinyl acetate. Mercuric acetate and boron trifluoride etherate were used as catalysts for the transvinylation of acids of the furan series. The structures of the vinyl esters obtained were proved by IR and PMR spectroscopy. The distribution of the π-electron density in the molecules of four of the synthesized vinyl and ethyl esters was studied by means of quantum-chemical calculations by the SCF MO LCAO method (Pople variant) using the Raman and UV absorption spectra.