5078 A simplified form of the relationship discussed in the Voltammetry of [(CZHJ~NI~BI~HI? at a rotating platinum electrode in acetonitrile (0.1 M tetraethylammoprevious paragraph is that the ratio of D values for the triplet and the corresponding quintets should be apnium perchlorate as supporting electrolyte) shows an proximately constant for a series of meta quintets. We anodic wave with Et/, = 1.5 v (us. sce). At a stationfind D V a / D I I I= a 5.8, D V b / D I I I= b 6.1, and D v I / D I v= ary platinum electrode, an anodic peak is observed at +1.5 v, with a shoulder at +1.85 v on a large anodic 6.4. The theoretical value of the D / E ratio should be -5 wave. In a typical run, 30 mmoles of NazBlzHlzin 150 for IV or for IIIa,b if the bonds to the divalent carbon ml of acetonitrile was exhaustively electrolyzed under are c ~ l i n e a r . ~ With , ' ~ IIIb, the one case in which E was nitrogen at 1.45 v, using a graphite cloth anode, with determined directly, the ratio is 3.6. A possible explanano supporting electrolyte. The current was monitored tion for this lower value lies in the potentiality for isousing a strip chart recorder; the value IZ = 0.91 equiv/ mers in the methylenes as these are known to be bent mole of Na2Bl2HlZwas found. The yellow solution about the divalent carbon atom. l,lS Simple theoretical was evaporated to dryness at room temperature, and argumentsg indicate that DIE < 5, -5, >5 for IIIb, the residue was dissolved in H 2 0 . Addition of CsF to VII, and VIII, respectively. Thus the absorptions used the aqueous solution gave white crystals of Cs3BZ1HZ3. for the assignment of parameters may arise from the 3H20 (I) which were recrystallized from an acetonitrileparticular isomer IIIb. water mixture. The possibility exists that some of the epr lines are Anal. Calcd for C S ~ B ~ ~ H ~ B, ~ .35.29. ~ H ~ Found: O : due to the quartet states such as IX which could be B, 35.10. The compound does not melt below 300". formally produced from IIIb. Arguments analogous to In a similar experiment, addition of (C2HJlNC1 to those used above to relate the parameters of the quintet the aqueous solution gave the corresponding tetrato those of the corresponding triplet may be used to ethylammonium salt of Bz4H233-. relate the quartet to those of a triplet and d o ~ b l e t . ~ ~ ' O Anal. Calcd for [(C?Hj)4N]3B~1H~1: C, 42.82, H, The predicted values for the quartet state should not 12.42; N, 6.24; B, 38.52. Found: C, 42.93; H, allow lines at as high or low magnetic fields as we ob12.72; N, 6.18; B, 38.66. serve experimentally. While quartet states may be Stationary-electrode voltammetry of I in acetonitrile present in the observed systems, the assignments we showed only the +1.85-v shoulder found in the voltare making are most probably based on quintet resoammetry of B12Hls2-. The conductivity of I in H2O gave Am = 462 ohm-' cm-I, typical of a 3 : 1 electrolyte. nances. A solution of compound I was passed through a Acknowledgments. We wish to thank Mr. R. M. strong acid ion-exchange column, and the liberated R. Cramer for his aid in determining the spectra and acid was neutralized with sodium hydroxide (equivalent Dr. J. Higuchi for interesting discussions. weight: calcd, 245.1, found, 246 + 1). The infrared (13) A. M ,Trozzolo, E. Wasserrnan, and W. A. Yager, J . A m . Chem. spectrum of 1 in KBr showed bands at 2500, 1050, Soc., 87, 129 (1965). and 940 and multiple bands from 750 to 710 cm-'. E. Wasserman, R. W. Murray, W.A. Yager A. M. T~OZZOIO, G . Smolinsky The IlB nmr spectrum of aqueous I at 32.0 Mc consisted of an unsymmetrical doublet at 15.4 ppm relaBell Telephotie Lnbotntories, hie. Miirrcry Hill, New Jeoey tive to external BF3.0(C2H&, with J = 130 cps. The Receiced July 27, 1967 100-Mc IH spectrum irradiated at 32.0 Mc consisted of two peaks of approximately equal intensities at +3.02 and +3.21 ppm from H 2 0 . The optimum deElectrochemical Oxidation of B 1 2 H d coupling frequencies for the two peaks differed by Sir: about 30 cps, which implies that the 'lB unsymmetrical doublet includes two doublets separated by less than 1 Recent work? has shown that the electrochemical oxidation of the BloHlo2-ion in acetonitrile parallels the ppm. The low-field lH peak was considerably broader under optimum decoupling conditions than was the aqueous chemical oxidation,3--j and that controlledhigh-field peak. potential electrolysis is a useful method of carrying out The controlled-potential electrolysis of B12Hn2- apthe oxidative coupling of BloHlo2-and its derivatives.6 parently parallels that of BloHlo2-, a one-electron oxidaPrevious attempts to oxidize B12H122-in aqueous solution followed by a dimerization reaction with the BIZ tion have been unsuccessful or have yielded only borates cage left intact. as products.'I8 We now report the controlled-potential oxidation of BI2Hlz2-in acetonitrile. R. J. R'iersema, R. L. Middaugh
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(1) Acknowledgment is made to the donors of the Petroleum Research Fund, administered by the American Chemical Society, and to the University nf I
