No abstract

Equilibrium and Kinetics of Several Hydroxyalkyl Radicals electric double layer now appears to have been determined.21 With regard to these factors we would only want to point out that the enhancement factor in the present case is higher than those found earlier in aqueous systems; in completely nonaqueous systems considerably larger factors have been found.7 •® 1283 Acknowledgment. The experimental assistance of Mrs. B. M. Huitín is gratefully acknowledged. The investigations were financed by Swedish Board for Technical Development.

The infrared spectra of YFs and YF2 isolated in argon and nitrogen matrices have been measured in the region 40-800 cm"1. The fundamental frequency assignments in argon assuming Cav symmetry for YFs are ¡^(E) 663 cm"1, f2(AD 119 cm"1, ^(E) 140 cm"1, with v-i unobserved. The frequency assignments for YF2 in nitrogen assuming C2u symmetry are 1/3(61) 538 cm"1, (AD545 cm"1, and i/2(AD 134 cm"1.The results show that YF3 is easily reduced to YF2 in a tantalum Knudsen cell.

Abstract

The ESR spectra of four radicals of the type RĊHCO2−, four of the type RĊ (O−) CO2−, and one each of the types R2ĊCO2− and ROHĊCO2− have been studied and the 13C hyperfine constants determined. The radicals were produced by continuous, in situ radiolysis of basic aqueous solutions of the appropriate acids. In all cases the radicals bore at least two units of negative charge, and radicals labeled with 13C at the natural abundance level were detectable because of the lowering of the recombination rate by this multiple charge. A typical radical of the first type is ĊH (CO2−)2 (aαC = 31.44 G, aβC = 11.92 G) derived from malonate. Also studied were radicals from succinate, citrate, and the anion of 1,2,3-propanetricarboxylic acid. In all cases where aαC could be determined, the values are close to 30 G. The values of aβC are also rather constant, being in all cases in the range 10–13 G. The hyperfine constants of the γ carbons (substituents on β carbons) in this type of radical are consistent with an angular dependence aγC ≅ 20 cos2 θ. A typical radical of the second type is CH3Ċ(O−;) CO2− (a αC = 14.09 G, aβC = 8.19, 6.35 G). The small 13C hyperfine constants of this type of radical (∼ 7–14 G) demonstrate the planarity of these radicals at the α carbon. Also studied was the radical −O2CCH2OĊHCO2− for which aαC was found to be 26.45 G. The low value of aαC shows that this radical is planar at the radical site and hence can serve as a reference for the values of aαC in hydroxyalkyl and ketyl radicals. The hyperfine constants of the radicals ĊH2CO2−, ĊH (CO2−)2, and HĊ(O−)CO2− are compared with values from INDO molecular orbital calculations.