L. S. Golovchenko

The character of interaction of organometallic derivatives of 4-nitrophenol and 4-nitrothiophenol with anions in different media

Interaction of RnM-derivatives of 4-nitrophenol and thiophenol (RnM= PhHG, PPh3Au, Ph3Sn, Ph4Sb) with a set of inorganic and organic anions (Cl−, Br−, I−, CN−, [PhOCO]−, [4-NO2C6H4OCO]−) was studied by IR and electronic spectroscopy in solvents with different polarities and coordinating properties (C6H6, CH2Cl2, DMSO). The dependence of the character of the interaction with the anions on the nature of the metal atom and heteroatom, the type of anions and the nature of the media was analyzed. Such interaction leads to ion-molecular complexes, and also to dissociation of the X-M bond (X = O, S, M = Au, Hg. Sb) with formation of the (4-NO2C6H4X)− anion even in weakly polar media. Only in the case of 4-NO2C6H4OSnPh3 does the reaction stop at the stage of complex formation. In other cases the role of complex formation with anions is less than with neutral coordinating reagents.

19F-NMR investigation of the comparative transmission capability of Hg-N bonds and the influence of the nature of the solvent on it

SummaryThe transmission of electronic effects of substituents in a number of arylmercury derivatives of 4-fluorobenzenesulfonanilides in inert and coordinating solvents has been studied by the19F NMR method. The binuclear bridge grouping Hg-N transmits electronic effects of substituents more strongly than an Hg bridge atom. The coordination interactions with the solvent substantially lower the transmission capacity of both mononuclear and binuclear organomercury systems, the quenching effect on the transmission of electronic effects of the substituents being considerably greater in the first case.

127I and79Br NQR spectra of halo-substituted phenols and phenylmercury phenoxides

The full127I NQR spectra of a series of iodo-substituted phenols and phenylmercury phenoxides have been studied. The quadrupole coupling constants and asymmetry parameters have been determined. The character of the OH...Hal hydrogen bond has been found to depend on the nature of substituents in the ring. Correlation dependences of the asymmetry parameters on the sum of the substituents resonance constants have been found for both coordinated as well as for non-coordinated iodine atoms.

Study of the effect of triarylphosphine ligands on chemical hardness of triarylphosphinegold cations

Exchange reactions with the participation of triarylphosphinegold and phenylmercury 4-fluorothiophenoxides, 4-nitrophenoxides, and acetates were studied by19F NMR spectroscopy. The data on the comparative chemical hardness of Ar3PAu+ and PhHg+ cations were obtained based on the data on the equilibrium constants. The chemical hardness of Ar3PAu+ cations increases as the electron-donating ability of triarylphosphine ligands increases. The effect of these ligands is described by the δ or δ° constants of substituted phenyl groups and by ionization potentials of their electron pairs or the pKa values.

Effect of aryl ligands on the chemical hardness of arylmercury cations

Abstract19F NMR spectroscopy was used to study the exchange reactions involving 4-fluorothiophenoxides, 4-nitrophenoxides, chlorides, and acetates of arylmercury and triphenylphosphinegold. The analysis of the data on equilibrium constants allows one to obtain information on the comparative chemical hardness of ArHg+ and Ph3PAu+ cations. The increase in the electron-donating ability of aryl ligands enhances the chemical hardness of ArHg+ cations, their influence being best described by σ0 constants of substituted phenyl groups.

19F NMR Study of the transmission capacity of binuclear-N(X)SO2-bridging groups

Conclusions1.A comparative19F NMR study of a series of model ArN(X)SO2C6H4F-4 compounds (X=H, HgPh, and Na) showed that the mechanism for the transmission of the substituent electronic effects in these compounds depends on the polarity of the Nδ−-Xδ+ bond. An increase in this polarity leads to an increase in the relative contribution of direct polar conjugation.2.The specific solvation of the mercury atom in the binuclear bridging N(HgPh)SO2 group has only a slight effect on its transmission capacity.

The transmission power of a bridging mercury atom

Conclusions1.It was established by the19F NMR method that the bridging mercury atom in compounds of the ArHgC6H4F-4 and ArCH2C6H4F-4 type transmits the electronic effects of substituants less effectively than the CH2 group.2.The decrease in the transmission power of the mercury atom in polar coordinating solvents results mainly from coordination interactions.

Influence of substituents on the chemical shift of fluorine in certain fluorosubstituted arylphenylmercury compounds and N-arylmercury derivatives of benzenesulfonanilide

Conclusions1.In a comparative investigation by the19F-{1H} NMR method of a series of mono- and binuclear bridge systems containing 3- and 2-fluorophenyl indicator groups ArHgC6H4F-3(2) and ArHgN(SO2Ph)C6H4F-(2), it was established that in both types of systems the chemical shift (CS) of fluorine in the 3 position, in contrast to the CS of fluorine in the 2 position, is determined chiefly by the electronic influence of the substituents.2.The 3-fluorophenyl indicator group in the compounds studied is less sensitive to the electronic influence of substituents than the 4-fluorophenyl group.3.In the presence of the effects of π- or σ,π-conjugation along the bonds of the bridge atom to the aromatic ring, the comparative transmission capacity of the bridge groups may vary with changing position of the indicator group in the aromatic ring.

19F NMR study of transmission capability of Hg-S and Sn-S binuclear bridge groupings

Conclusions19F-{1H} NMR has been used to investigate the comparative efficiency of transfer of electronic effects of substituants (EES) through metal-sulfur binuclear bridge groupings, in model systems ArnMSC6H4F−4 (M=Hg, Sn, CH2; n=1, 3). In transmission capability, Hg-S and Sn-S are very little different from the mononuclear analogs Hg and Sn. The order of arrangement of the units in the Hg-S bridge has no effect on the transmission capability. The CH2-S bridge has a greater transmission capability than Hg-S. The EES transfer efficiency through the metal-sulfur bridge is much lower in coordinating polar solvents. An estimate has been made of the relative contributions of dipole-dipole and coordination interactions with the solvent to the overall effect in lowering the transmission capability.

35Cl,79Br, and127I NQR spectra of several polyhalophenols and their phenylmercury derivatives

Conclusions1.The intramolecular contribution to the splitting of the NQR frequencies in the 2,6-dihalo-4-X-derivatives of phenol has been separated out. The strength of the intramolecular hydrogen bond is substantially dependent on the nature of the substituants in position 4. The splittings in the NQR spectra are reduced upon passing from electron-accepting substituents to electron-donating substituents.2.The intramolecular coordination interactions of mercury atoms with halogen atoms leads to a reduction and splitting of the NQR frequencies of the halogen atoms in positions 2 and 6 and they are only slightly dependent on the substituent in position 4.