1510
COMMUNICATIOXS TO THE EDITOR
Vol. 79
others. The simplest interpretation of the data is that each maximum represents the major absorption band (but not necessarily the only one) for successive complexes of copper(I1) ion with bromide ion. Since there are six such bands in methanol, ethanol, n-butanol, and isopropyl alcohoL3 we ascribe the bands to CuBr+, CuBr2, CuBrs-, CuBr4--, CuBr6---, and CuBr6----. The band positions are given in Table I.
reported previously. 1 , 2 ~ 5 , 4 , 5 For cxample, the oxidation of l-amino-2,6-dicyano-B,(j-dirnethylpiperidine with bromine in aqueous ethaiiol gave a theoretical yield of nitrogen, cis- and truns-l,%dicyano1,2-dimethylcyclopentane and 2,6-dicyanoheptene-2.' Busch and Weiss3 reported bibenzyl as the principal product when 1,ldibenzylhydrazine was treated in ethanolic solution with mercuric oxide. We have confirmed this interesting result and obtained an S2.5% yield of bibenzyl and 98% evoluTABLE I" tion of nitrogen in ethanol at 57'. Solvent The cis and t r a m isomers of l-amino-2,G-diSpecies HO€Ib MeOH EtOH n-BuOH i-PrOII phenylpiperidine were prepared via the N-iiitroso CuBr+ 283 306 310 314 310 compounds (cis nitroso, 1n.p. 66.5-07.5', Anal. CuBr:! 238 i.4 245 i:4 252 f 4 248 f Sd Calcd. for Cl~Hl8r\T2G:C , 76.60; H, 6.81; N , CuBrs- 338 339 =t3 344 346 350 f 3 10.52. Found: C, 'iG.65; H, 6.77; X, 10.31. 27 9 277 CuBr4' 271 275 277 trans, m.p. 87-88', Found: C, 76.44; H, 6SB; CuBrj" 573 576 578 575 f 5d N, 10.30) and oxidized with mercuric oxide at 58' (638)" in ethanol. The cis- l-ainino-2,6-diphenylpipericline CuBr6.Z.- 511 522 524 525 52 1 (m.p. 133-134', A,ml. Cslcd. for C l i H d z : C , a Band positions are considered accurate to 1-2 mp, 80.91; H, 7.99; N, 11.10. Found: C . 80.74; unless otherwise noted, and have not been corrected t o 13, 8.09; N, 11.37) or1 oxidation gave a 64.5% equivalent ionic strengths [e.g., CuBr+ maximum: 1n.p. 45.80.5 X 310 r n p ; p 50 X 3OSrnp, EtOH]. Bands yield of cis-1,2-diphenylcyclopentaneJ with overlap considerably. Presumably obscured by C u + + 47', a 25y0 yield of 1,5-diphenyl-l-~entene,~ and Br- absorptions. Was observed only as a shoulder a t a 1 0 0 ~ o evolution of nitrogen. An infrared specSee footuote 3. the concentrations used. trum of the mixture of products indicated tlie presence of only the two aforementioned products. The startling result in Table I is the clear alter- The infrared spectrui t i of the cis-1,2-dipheriylcyclonation in excitation energies for successive odd and pentane was identical with an authentic sa~iiple,~ even complexes. Equilibrium dataza signify that m.p. 46-47' prepared according to Jappe and Lanmost of the differences must be a t the level of the der.8 mixture melting point 45.547' The presexcited states. An oversimplified picture for the ence of 1,5-diphenyl-l-pentene was established transition, presumably one of charge-transfer,4 by preparing the 2,4-dinitrobenzeiiesulfenyl chloe.g., CuBrs- -+ CuBr2-.Bro, suggests that excited ride derivative, m.p. 114-115.5', from the mixture states with even numbers of halide ions are more of products. A mixture mclting point with the stable than those with odd numbers. A similar derivative prepared from an authentic sample of situation exists for copper(I1) chloride complexes5 1,5-diphenyl-l-pentene, m.p. 113.3-115' (Anal. and may be true for ferric complexes with two, Calcd. for C23H2104K\;2SC1:C, 60.46; 13, 4.63; N, three, and four chloride ions.6 6.13. Found: C, 60.52; 13, 4.46; N, 6.32) The relationship of the transition associated melted at 113-115'. Oxidation of the cis-1with CuBr+ in alcohols to that in water can be aniino-2,6-diphenylpiperidinewith potassium pershown approximately by plotting the transition manganate in acetone solution gave a 3.Z0 yield energies against the transition energies for the of cis-l,2-diphenylcyclopentane and an %yoeL701ucharge-transfer band of 1-methyl-4-carbomethoxy- tion of nitrogen. pyridiniuin iodide complex in the same solvent^.^ Oxidation of traizs-l-amino-2,B-diphenylpiperiAcknowledgment.-The authors wish to ex- dine, 1ii.p. SO-81' ( A d . Calcd. for Cl7HzoNe: press their appreciation to Dr. Edward L. King of C, 80.91; H,7.99: N, 11.10. Found: C, 80.71; this Department for many helpful discussions. €1, 7.89; N, 10.93) with mercuric oxide at 58' in ethanol gave a 59% yield of ii,aizs-l,9-diphe~lyl(3) I n this solvent a seventh band, apparently linear in copper(I1) concentration, appears with certain copper(I1)-bromide combinations. cyclopentane, n1.p. 64-6z07,a ET0 yield of cis-1,2(4) l
