878499-76-4Relevant academic research and scientific papers
Effect of π-accepting substituent on the reactivity and spectroscopic characteristics of triarylbismuthanes and triarylbismuth dihalides
Rahman, A.F.M. Mustafizur,Murafuji, Toshihiro,Ishibashi, Motoko,Miyoshi, Youhei,Sugihara, Yoshikazu
, p. 3395 - 3401 (2007/10/03)
Competitive chlorination of p-substituted triarylbismuthanes 1 [(p-XC6H4)3 Bi; a: X = OMe, c: Cl, d: CO2Et, e: CF3, f: CN, g: NO2] and trimesitylbismuthane (2,4,6-Me3C6H2) 3Bi 1h by sulfuryl chloride was carried out against 1b (X = H) and the effect of these substituents on the formation of triarylbismuth dichlorides 2 was studied. The relative ratios 2/2b decreased with increasing electron-withdrawing ability of the substituents (2a/2b = 53/47, 2c/2b = 33/67, 2d/2b = 35/65, 2e/2b = 29/71, 2f/2b = 16/84, 2g/2b = 0/100, 2h/2b = 46/54), indicating a lowering of reactivity of the lone pair on the bismuth atom. Pd-Catalyzed degradation of 2a-g and their difluorides 3 giving biaryls 4 was promoted by the electron-withdrawing p-substituents in the equatorial aryl groups but suppressed by the more electronegative fluorine atoms in the apical positions. This is in fairly good accord with the stability of the trigonal bipyramidal geometry. The 13 study of 1-3 showed that the signals due to the ipso carbons (C1) attached to the bismuth atom shift downfield with increasing electron-withdrawing nature of the p-substituents. No such tendency was observed in other aromatic ring carbons. The electronic effect on the C1 atoms, similar to that on the chlorination of 1 and degradation of 2 and 3, indicates the significant participation of the C1 atoms in these reactions through the Bi-C1 bonds.
Unexpected formation of highly stabilized tetrakis-(2-alkoxyphenyl)bismuthonium salts in the oxidation of tris-(2-alkoxyphenyl)bismuthanes with iodosylbenzene
Suzuki, Hitomi,Ikegami, Tohru,Azuma, Nagao
, p. 1609 - 1616 (2007/10/03)
Treatment of tris-(2-alkoxyphenyl)bismuthanes 1 with iodosylbenzene in methylene dichloride at 40°C led to none of the expected bismuthane oxides 2 but, quite unexpectedly, gave tetrakis-(2-alkoxyphenyl)bismuthonium chlorides 3 in moderate to good yields. In some cases, bismuthonium formates 4 accompanied the main reaction products. Similar treatment in benzene in the presence of benzyl bromide, ethyl bromide, or 2,2,2-trifluoroethyl iodide led to the corresponding bismuthonium bromides 7 and iodides 8. Through anion exchange, a variety of bismuthonium salts including formate 4, tetrafluoroborate 11, toluene-p-sulfonate 12, bromide 7, iodide 8 and perchlorate 13 were prepared from the salt 3 in good yields. In contrast to the known tetraphenylbismuthonium salts, all of these new bismuthonium salts exhibited high thermal stability. The molecular structure of compound 7a was elucidated by X-ray analysis, where the four neighbouring oxygen atoms are found to surround the bismuth atom tetrahedrally via a weak through-space interaction with the metal, making the bismuth centre less susceptible to nucleophilic attack of the halide anion.
