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Hypervalent (HV) iodine­(III) compounds with fluorine-containing ligands (F, CF3, C6F5CO2, or CF3(CF2)8CO2 (n-C9F19CO2)) reacted, in the presence of iodine or copper salts, with the double bonds in cis-1,4-polyisoprene (polyIP) to afford fluorine-containing polymers. For instance, fast iodo-fluorination of polyIP was accomplished in the presence of 4-(difluoroiodo)­toluene (4-TolIF2) and iodine. The reaction of polyIP with 1-trifluoromethyl-1,2-benziodoxol-3­(1H)-one (Togni reagent II) and copper­(I) iodide under mild conditions yielded polymers with vicinal pendant trifluoromethyl and 2-iodobenzoate groups, which were subjected to acid-promoted elimination to give a fluorine-containing unsaturated polymer. The simultaneous introduction of trifluoromethyl groups and a halogen (Cl or Br) was achieved by reacting polyIP with Togni reagent II in the presence of thionyl halide and copper­(II) salts. The alkyl chloride pendant groups in the product of the copper-mediated reaction of polyIP with thionyl chloride and Togni reagent II were subsequently converted to azide functionalities by nucleophilic substitution with NaN3, and the produced azide-containing polymer was subjected to copper­(I)-catalyzed “click” coupling reaction with a fluorescent alkyne, propargyl 4-(1-pyrenyl)­butyrate. Perfluoroacyloxy pendant groups were also introduced successfully by the reaction of polyIP with HV iodine­(III) reagents with perfluorinated carboxylate ligands, i.e., C6H5I­(O2CC6F5)2 and C6H5I­(O2C­(n-)­C9F19)2, in the presence of iodine. No significant chain degradation and/or cross-linking was observed in any of the functionalization reactions. The modified polymers showed relatively good thermal stability and high hydrophobicity, with contact angles toward water in the range of 89–116°.

Hypervalent iodine(III) compounds with tetrazole ligands C6H5I(N4CR)2 (R  CH3, C6H5, 4‐CH3C6H4) reacted, in the presence of elemental iodine, with the double bonds in cis‐1,4‐polyisoprene (polyIP) to afford iodo‐tetrazolylated polymers. The alkyl‐iodide groups in the products of the polyIP functionalization were utilized as macro chain‐transfer agents for the iodine‐transfer polymerization of methyl methacrylate, which yielded brush polymers with well‐defined poly(methyl methacrylate) side chains. In addition, the iodo‐tetrazolylated polymers were reacted with NaN3 in DMF at room temperature, and it was noticed that, in addition to nucleophilic substitution, elimination reactions took place. However, the presence of azide groups was taken advantage of and successful click chemistry‐type of grafting‐onto reactions were carried out with alkyne‐capped poly(ethylene oxide) in the presence of CuBr and N,N,N′,N″,N″‐pentamethyldiethylenetriamine. The thermal decomposition of both the iodo‐tetrazolylated and the azido‐tetrazolylated polymers was exothermic, especially for the latter materials. © 2019 Wiley Periodicals, Inc. J. Polym. Sci. 2020, 58, 172–180

No abstract

Tetrazoles are well known for their high positive enthalpy of formation which makes them attractive as propellants, explosives, and energetic materials. As a step towards a deeper understanding of the stability of benziodazolotetrazole (BIAT)-based materials compared to their benziodoxole (BIO) counterparts, we investigated in this work electronic structure features and bonding properties of two monovalent iodine precursors: 2-iodobenzoic acid and 5-(2-iodophenyl)tetrazole and eight hypervalent iodine (III) compounds: I-hydroxybenzidoxolone, I-methoxybenziodoxolone, I-ethoxybenziodoxolone, I-iso-propoxybenziodoxolone and the corresponding I-hydroxyben ziodazolotetrazole, I-methoxybenziodazolotetrazole, I-ethoxybenziodazolotetrazole and I-iso- propoxybenziodazolotetrazole. As an efficient tool for the interpretation of the experimental IR spectra and for the quantitative assessment of the I−C, I−N, and I−O bond strengths in these compounds reflecting substituent effects, we used the local vibrational mode analysis, originally introduced by Konkoli and Cremer, complemented by electron density and natural bond orbital analyses. Based on the hypothesis that stronger bonds correlate with increased stability, we predict that, for both series, i.e., substituted benziodoxoles and benziodazolotetrazoles, the stability increases as follows: I-iso-propoxy < I-ethoxy < I-methoxy < I-hydroxy. In particular, the I−N bonds in the benziodazolotetrazoles could be identified as the so-called trigger bonds being responsible for the initiation of explosive decomposition in benziodazolotetrazoles. The new insight gained by this work will allow for the design of new benziodazolotetrazole materials with controlled performance or stability based on the modulation of the iodine bonds with its three ligands. The local mode analysis can serve as an effective tool to monitor the bond strengths, in particular to identify potential trigger bonds. We hope that this article will foster future collaboration between the experimental and computational community being engaged in vibrational spectroscopy.