J . Am. Chem. SOC.1986, 108, 1441-1447 0.8 e ,k3 were found in the final difference Fourier map very near the methyl carbons of the diethylaluminum moiety. All other peaks were less than 0.6 e .k3.All calculations were carried out on a VAX 11/750 computer with the CRYRM system of programs. [Cp2Zr(C,0-~2-OCCHCH2CMe3)]z(p-H)(p-AIEt2) (X). A toluene solution of Ia (1.057 g, 1.58 mmol) was treated with several equivalents (0.400 mL, 3.77 mmol) of neat Et2A1H. A deep yellow solution formed and was stirred for 24 h at 80 OC. Removal of solvent in vacuo afforded a dark brown waxy residue that was washed with four 15-mL portions of cold (-30 “C) hexane to yield X as a white powder (0.444 g, 0.589 mmol). The dark brown washings were evacuated to dryness, redissolved in toluene, and stirred at 80 OC for an additional 6 h. Workup in a similar manner provided an additional 0.094 g (0.125 mmol) of X. Recrystallization of 0.100 g of X from 5 mL of Et,O-hexane (3/2) at -20 OC afforded crystals suitable for X-ray diffraction: IR (Nujol) 2800 (vs), 2750 (vs), 1630 (m) (uC4), 1630 (s), 1310 (m), 1290 (m), 1255 (w), 1195 (w), 1180 (w), 1155 (w), 1020 (m), 1110 (m), 975 (m), 940 (m), 900 (m), 875 (m). 820 (s), 780 (s) cm-’. X-ray Structure Determination of [Cp2Zr(C,0-v2OCCHCH,CMe,)h(~H)(r-ALEt,) (X). A crystalline block (0.35 X 0.30 X 0.25 mm) of X was mounted approximately along (I in a glass capillary under N,. A series of oscillation and Weissenberg photographs indicated monoclinic symmetry and the space group C2/c (hkl absent for h + k odd, hOl absent for I odd); data were collected on a Enraf-Nonius CAD-4 diffractometer with a graphite monochromator and Mo K a radiation (A = 0.7107 A). The unit cell parameters (Table 11) were calculated from the setting angles of 25 reflections in the range 20 < 28 < 35O. A total of 9443 reflections, comprising four symmetry-equivalent data sets, were averaged to give a total of 2845 reflections. The three check reflections, collected every loo00 s of exposure time, showed no significant deviations
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in their intensities. The correction for absorption was negligible (w = 0.544 mm-I). The form factors were taken from Table 2.2B, Vol. IV, “International Tables for X-Ray Crystallography” (1 974) for all atoms. The position of the Zr atoms was derived from the Patterson map, and the Fourier map phased on this atom revealed the remainder of the structure. All H atoms were introduced into the model with fixed coordinates at idealized positions and individual isotropic W s equal in magnitude to that of the adjacent heavy atom, plus 10-20%. Leastsquares refinement of all non-hydrogen atoms with anisotropic U,;? the scale factor, and the two parameters of the hydride H atom 0,coordinate , all the data (2845 reflecand U), minimizing x w [ F 2- ( F , / k ) 2 ] 2with tions) led to S = 1.76, RF = 0.049, and RF = 0.033;s6 final shift/errors 3 days indicated sub-ppm levels of contaminants in the argon atmosphere). 3-Butenylbenzene (2) was prepared by coupling benzylmagnesium chloride with allyl bromide.6' Distillation afforded pure 2 by GC analysis. The ' H N M R of 2 was in agreement with reported N M R data.62 I-Methylindan (1) was prepared by methylation of 1-indanone (Aldrich) with methyllithium (Aldrich) followed by reduction with Li/ NH,/NH,C1.63 Purification by distillation yielded pure 1 (GC analysis), whose ' H N M R was in agreement with reported spectral data.64 o-(3-Butenyl)bromobenzene (3) was prepared by coupling o-bromobenzyl bromide with allylmagnesium chloride. A solution of o-bromobenzyl bromide (Aldrich) (6.34 g, 25.37 mmol) in T H F (30 mL) was added dropwise with stirring to a T H F solution of excess allylmagncsium ~~~
~~
~
(59) Gores, G. J.; Koeppe, C. E.; Bartak, D. E. J . Org. Chem. 1979,44, 380-385. (60) For further experimental details on solvent-electrolyte purification procedures, see: Koppang, M. D.; Woolsey, N . F.; Bartak, D. E. J . Am. Chem. Sac. 1984, 106, 2799-2805. (61) Hurd, C . D.; Bollman, H. T.J . Am. Chem. Sac. 1933,55,699-702. (62) Reich, H. J . ; Shah, S. K.; Chow, F. J . Am. Chem. Sac. 1979, 101, 6648-6656 . . . ...
(63) Lipsky, S. D.; Hail, S. S. Org. Syn. 1976, 55, 7-1 1 . (64) Franz, J. A,; Camaioni, D. M. J . Org. Chem. 1980,45, 5247-5255.
Reactions of 0-(3-Butenyllphenyl Anions and Radicals chloride (0.9 M X 150 mL, 135 mmol). All of the Mg metal must be removed from the Grignard solution before addition of the bromide reagent for optimum yields. After addition was completed, the solution was refluxed for 1.5 h. Excess Grignard reagent was quenched with 10% H 2 S 0 4 (50 mL). The butene was extracted with diethyl ether, washed with saturated NaCI, and dried over MgSO,. Removal of solvent followed by vacuum distillation (bp 1 14 OC (17 mm)) yielded 4.74 g of clear liquid (22.5 mmol, 89% yield) that exhibits the following: ' H N M R (CDC13) 6 6.80-7.60 (m, 4 H), 5.50-6.10 (m, 1 H), 5.05 (d, J = 8 Hz), 4.80 (s, 1 H), 2.80 (t, J = 7 Hz, 2 H), 2.25 (q, J = 7 Hz, 2 H); "C N M R (CDCIJ 6 141.06, 137.61, 132.81, 130.40, 127.61, 127.35, 124.55, 115.26, 35.67, 33.80; mass spectrum (GC-MS) m/z (relative intensity) 212 (M+m8IBr,2), 210 (M+.79Br, 3), 171 (loo), 169 (97), 131 (54), 130 (31), 90 (23), 89 (22), 63 (13), 51 (11). Diisopropyl ether (Aldrich) was deoxygenated on the vacuum line (freeze-pumpthaw) and dried by passage through a column of activated alumina in the glovebox. 2-Propanol-d (98+ atom % D) and deuterium oxide (99.8 atom % D, Gold Label) were purchased from Aldrich and used as received. Sodium isopropylate was prepared by combining sodium metal (0.04 g-atom) with spectroscopic-grade 2-propanol (50 mL) (J. T. Baker) under N,, heated (40-60 "C), and stirred until all of the metal had reacted. Excess alcohol was removed by heating (IOC-1 IO "C) under vacuum to yield the alcoholate, which was transferred and stored in the glovebox. Controlled-Potential Electrolysis and Product Analysis. Controlledpotential electrolyses of bromobenzene and 3 were conducted a t -2.65 and -2.25 V vs. SCE for direct electrode and mediated reductions, respectively. Electrolyses were terminated after the addition of 1 F mol-', unless otherwise indicated (Tables 1-111). Upon completion of an electrolysis, HCIOI was added to the solution under a positive argon atmosphere. Products from electrolyzed solutions of 3 were quantitatively extracted into diethyl ether in the following manner. An internal standard nnaphthalene) and an aliquot of electrolyzed solution ( I O mL) were added to water (20 mL) and ether (20 mL). The aqueous and organic layers were cooled (ice bath), filtered, acidified (5% HCI, pH C2 for aqueous phase), and separated. The aqueous phase was extracted with ether (3 X 5 mL) and all organic extracts were combined. The ether extract was washed with 5% HCI (3 X 5 mL), dried (MgSO,), and filtered. The extracted solutions were qualitatively and quantitatively analyzed by gas chromatography on a Shimadzu GC-6AM G C equipped with I/&., all-glass packed columns (3% Dexsil 300 on Supelcoport, 100/120 mesh, 6-m) and FID detectors. The G C was coupled to a Hewlett-Packard (3390A) recording integrator. Qualitative identification was accomplished by spiking techniques. Quantitation of products was achieved by using response factors obtained for standard solutions of the observed products with respect to naphthalene. Product quantitation by G C analysis was periodically cross-checked by high-pressure liquid chroma-
J . Am. Chem. SOC.,Vol. 108, No. 7, 1986
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tographic analysis on a Waters Associates 6000A HPLC equipped with a Model 660 solvent programmer. The electrolyzed solutions of 3 were injected directly onto a 0.25 in. X 25 cm Alltech C18 column with a IO-pn mean particle-size packing. Products were identified by spiking techniques and were separated under isocratic eluent conditions (50% acetonitrile/50% water; flow rate = 1 mL min-I). Calibration curves were prepared and employed for product quantitation. Quantitation of products from the bromobenzene electrolyses was accomplished by HPLC analysis using similar methodology. Electrolyzed solutions were directly injected onto the C18 column and products were separated under the aforementioned eluent conditions. Electrolyzed solutions were extracted with diethyl ether (vide ante) for qualitative G C analysis. Additional qualitative product analyses and deuterium-incorporation measurements were performed on extracted electrolysis solutions of 3 and bromobenzene by gas chromatography-mass spectroscopy (GC-MS). The extracted solutions were injected onto a Hewlett-Packard G C (Model 5790A) (25 m, OV-17 WCOT capillary column) equipped with a Hewlett-Packard mass-selective detector (Model 5970A). Chromatographic peaks were assigned to products by comparison of the resultant spectra with published spectra65or characteristic spectral fragmentation patterns. Deuterium-incorporation measurements for benzene, 3-butenylbenzene, and 1-methylindan were obtained from mass-spectral data analysis (GC-MS) using a procedure that has been described in Evidence for multiple deuterium atom incorporation was not observed for the electrolysis products of benzene, 1, or 2. In addition, deuterium incorporation for 1 and 2 was only observed in the methyl group for the former and in the ring for the latter compound.
Acknowledgment is made t o the donors of the Petroleum Research F u n d , administered by t h e A m e r i c a n C h e m i c a l Society, for support of this research. The MSD for t h e GC was acquired with NSF funds under G r a n t C H E - 8 3 0 8 0 4 2 . Registry NO. 1, 767-58-8; 2, 768-56-9; 3, 71813-50-8; 4, 100312-1 1-6; 5, 57056-96-9; 6, 75421-38-4; DZO, 7789-20-0; Pt, 7440-06-4; Hg, 7439-97-6; bromobenzene, 108-86-1; benzene, 7 1-43-2; benzene-d, 1120-89-4; m-tolunitrile, 620-22-4; diisopropyl ether, 108-20-3; sodium isopropylate, 683-60-3; 2-propanol-d, 3979-5 1-9; phenyl anion, 3092278-2; phenyl radical, 2396-01-2; o-bromobenzyl bromide, 3433-80-5; allylmagnesium chloride, 2622-05- I . (65) 'EPA/NIH Mass Spectral Data Base", Nutl. Bur. Stand. (US.) Circ. 1978, NSRDS-NBS 63.
(66) (a) Biemann, K. "Mass Spectrometry: Organic Chemical Applications"; McGraw-Hill: New York, 1962; Chapter 5 , pp 223-227. (b) Koppang, M. D. Ph.D. Dissertation, University of North Dakota, Grand Forks, ND, 1985.
