Reaction of polyamine polymer with molecular iodine via charge-transfer complex formation

The reaction of a Mannich base type-polyamine polymer with iodine (I₂) was studied kinetically and thermodynamically in order to clarify the polymer effects in the formation of triiodide ions (I₃^?). N,N-Dimethyl-p-(4-methylpiperazinomethyl) aniline and 1,4-dimethylpiperazine were used as low molecular weight donor model compounds. Triiodide ions are produced from the polyamine–I₂ system immediately after mixing the two-component solutions, while in the systems with I₂ and N,N-dimethyl-p-(4-methyl-piperazinomethyl)aniline and 1,4-dimethylpiperazine they are obtained only when relatively high concentrations of both donor and acceptor solutions were mixed. This is explained by the entropic contributions of the polymer chain such as the stacking effect of donor nitrogen atoms, i.e., the increment of local donor concentration around I₂ in the reaction field. The relation between the solution behavior of the reaction systems and the rate of formation of I₃^? ions also supports this kind of polymer effect. The effects of neighboring groups and dielectric constant on the reaction are also discussed.     

Calorimetric investigations of the solvent effect on complex formation between pyridine derivatives and molecular iodine

The heats of solution of isoquinoline and 2,4-lutidine and heats of 11 complex formation with molecular iodine inn-hexane, cyclohexane, CCl₄, benzene, and chlorobenzene have been determined by the calorimetric method. The heats of transfer of the donor and donor-acceptor complex from nonsolvating medium (n-hexane) to the particular solvent were calculated and discussed in terms of donor and solvent properties and solute-solute-solvent interactions.Presented at the IV International Symposium on Solute-Solute-Solvent Interactions, Vienna, September 11–16, 1978, pp. 152–154.     

The formation of bifurcated charge transfer complexes with molecular iodine

I₂ complexes with triptycene and several di- and triaryl derivatives of methane and ethane were studied. For these complexes the values of λ_CT are virtually identical to those reported for the complexes with the analogous monoaryl donors, while the values of λ for their blue shifted I₂ peaks are significantly lower than those for the monoaryl complexes. Both the equilibrium constants and - ΔH⁰ values for the formation of complexes from the components lead to the conclusion that the complexes with the di- and triaryl compounds are more stable than those with the monoaryl donors. For the diaryl donors, the ΔS⁰₂₉₈ values for complex formation are less favorable than those of the monoaryl donors. The dipole moment for I₂ in diphenylmethane is larger than the moment of I₂ in toluene. All of these observations can be explained by taking into account the transannular effect of one aromatic ring on another and viewing the complexes as bifurcated ones in which the I atom at one end of an I₂ molecule simultaneously interacts with two rings in the donor molecules.     

Formation of a 1-azaallenylidene ligand by reaction of an amido complex with tetracyanoethylene

Amido complexes of Mo(II) allyl carbonyl fragments containing monodentate amido ligands, prepared by reaction of suitable chloro precursors with potassium amides, react (for the N(H)(p-tolyl) derivative) with tetracyanoethylene to give a 1-azaallenylidene complex.     

Study of complex formation by cyclopropane with molecular chlorine in the liquid phase

Journal of Structural Chemistry -     

Spectroscopic analysis of charge transfer complex formation between neuroleptics and iodine

Molecular interactions between iodine and various neuroleptics were investigated by UV/Vis spectroscopy. Iodine was found to form charge transfer complexes in a 1:1 stoichiometry and of n-sigma type with these molecules. The values of the formation constants Kc of these iodinated complexes indicate a strong donor-acceptor interaction. These drugs can therefore be expected to interfere with thyroid metabolism.     

Resonance Raman study of a two-chromophore system. The 2:1 complex of hexamethylbenzene with tetracyanoethylene

Raman excitation profiles are presented for the 2:1 electron donor-acceptor (EDA) complex of hexamethylbenzene (HMB) and tetracyanoethylene (TCNE) in cyclohexane. Though the absorption and Raman spectra of the 1:1 and 2:1 complexes are similar, distinct differences are found in the Raman excitation profiles (REPs) of vibrational modes common to both systems. REPs of the 2:1 complex show intensity cancellation that is taken as evidence for interference of two charge-transfer excited states. The implications of the observed spectra concerning excited state electron delocalization are considered.     

The molecular complex of 4-(N-pyridinium)pyridine-N-oxide chloride with tetracyanoethylene in the synthesis of substituted pyridine N-oxides

The structure of the complex of 4-(N-pyridinium)pyridine-N-oxide chloride with tetracyanoethylene was studied by¹³C NMR spectroscopy. The results of the investigation, suggesting the use of this complex in the synthesis of substituted pyridine derivatives, were conformed experimentally by its reaction with oxygen and with nitrogen-containing nucleophiles.Petrozavodsk State University, Petrozavodsk, 185640. St. Petersburg State University, St. Petersburg, 198904. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 184–186, February, 1995. Original article submitted December 24, 1994.     

Spectrophotometric study of molecular complex formation between o-chloranil and a series of methylated pyridines

o-Chloranil has been shown to form 1:1 molecular complexes with pyridine and 2-, 3- and 4-picolines in CCl4 medium. Isosbestic points have been found but charge-transfer bands could not be detected. The formation constants of the complexes exhibit a very good linear free energy relationship from which the Hammett p parameter for the complexation reaction is found to be -3.67.     

Unusual cycloaddition of a cage ketone with tetracyanoethylene by irradiation of the electron donor-acceptor complex.

The photochemical reaction of an electron donor-acceptor complex of a cage ketone containing a cyclobutane ring with tetracyanoethylene (TCNE) gave an unusual 1:1 adduct which is considered to be formed by interception of a 1, 4-radical cation by TCNE-..     

Aza-Ferrier rearrangement of glycals with amides promoted by molecular iodine

Amidoglycosidation of tri-O-acetyl-d-glucal with different N-nucleophiles such as t-butyl carbamate, N-benzyl carbamate, N-ethyl carbamate, tosyl amide, and mesyl amide has been achieved using an equimolar amount of molecular iodine under mild and neutral conditions to afford the corresponding N-glycosyl amides in good yields with a preferential α-anomeric selectivity. The use of iodine makes this method simple, convenient, and cost-effective. This is the first report on aza-Ferrier rearrangement using molecular iodine.     

A matrix isolation i.r. study on molecular complexes of hexamethylbenzene and tetracyanoethylene

The i.r. spectra of Ar and N₂ matrices containing trapped hexamethylbenzene (HMB), tetracyanoethylene (TCNE) and their complex species are presented. The formation of complex species (essentially the 1:1 complex) is indicated by the arising of new bands at 1295 cm⁻¹ (the A_1g CCH₃ stretching of HMB) and at 1546 cm⁻¹ (the CC stretching of TCNE). However, the comparison with the spectra of the crystalline 1:1 and 2:1 complexes (HMB:TCNE), indicates that the contribution of vibronic mechanisms to band intensities is greatly reduced by the isolation of complex units in the matrix.     

Regio- and stereoselective iodoarylation of arylacetylenes using molecular iodine promoted by hypervalent iodine

Iodoarylation of arylacetylenes with electron-rich arenes using a simple reagent system: I₂ and PhI(OCOPh)₂ proceeded regio- and stereoselectively to give trans adducts, 1,1-diaryl-2-iodoethenes, in good to high yields.