1620
Organometallics 1991, 10, 1620-1622
Fourier maps. Anisotropic temperature factors were introduced for all non-hydrogen atoms. Hydrogen atoms were added at calculated positions and included in the structure factor calculations with a common thermal parameter (U= 0.08 A2). Of 8394 reflections, measured with an 28-u scan technique in the range 3 < 28 < 50°, 4630 having Z > 3a(4 were used to refiie 518 parameters to final residuals of R = 0.045 and R, = 0.049. The weighting scheme used in the last refinement cycles was w = 1.000/(~(F0)+0.001163F~), which showed reasonable consistency in a test of wA2 for data sectioned with respect to both Foand (sin @)/A. Scattering factors for non-hydrogen atoms were taken from ref 28 and for hydrogen atoms from ref 29. Anomalous dispersion corrections for Rh, Pd, C1, and P atoms were taken from ref 30. All calculations were performed with s ~ ~ ~ x and 7 6 PARSF 9 ~ seta ne.
of programs on the IBM 4341 computer at the "Centro di Calmlo dell' Universiti di Messina". The refined structure waa plotted with use of the ORTEP program (Figure 1). Full lists of bond
distances and angles, hydrogen coordinates, anisotropic temperature factors, and calculated and observed structure factors are available as supplementary material. Non-hydrogen coordinates are shown in Table I.
Acknowledgment. We thank the CNR (Rome) and the Public Education Ministry for financial support. Supplementary Material Available: Tables listing crystallographic parameters, anisotropict h e d parameters for non-H atoms, fractional atomic coordinates for H atoms, and complete bond lengths and angles (5 pages); a table of structure factors (26 pages). Ordering information is given on any current masthead page.
(28) Cromer, D. T.;Mann, J. B. Acta Crystallogr., Sect. A 1968,24,
dLl.
(29) Stewart, R. F. J . Chem. Phys., 1970,53, 3175. (30) International Tables for X-ray Crystallography; Kynoch Press: Birmingham, England 1974; Vol. IV.
(31) Sheldrick, G.M.System of Computing Programs. University of Cambridge, 1976. (32) Nardelli, M. Comput. Chem. 1983, 7, 95.
Rhodium( I I I ) Biphasic and Phase-Transfer-Catalyzed Hydrogenolysis of Chloroarenes under Exceptionally Mild Conditions Vladimir V. Grushin and Howard Alper' Oifawa-Carleton Chemlstry Institute, Department of Chemistry, University of Ottawa, Ottawa, Ontario, Canada K I N 6N5 Received October 30, 1990
The rhodium(II1) complexes L2Rh(H)C12[L = tricyclohexylphosphine or triisopropylphosphine] are excellent catalysts for the hydrogenolysis of chloroarenes. The reaction proceeds under biphasic [40% NaOH, PhCH,] conditions, or to give somewhat higher product yields, under phase-transfer conditions, using benzyltriethylammonium chloride as the quaternary ammonium salt. The reaction occurs under mild conditions, and many functional groups [e.g. R, OR, CF3, COAr, COOH, NH2] are compatible for the carbon-chlorine bond cleavage process. Carbon-halogen bonds in aromatic compounds are usually quite resistant to reactions with nucleophiles and transition metal complexes. Aryl iodides, which are expensive, are able to undergo Ullmann' and SRNltype2 transformations. They can also participate in transitionmetal-catalyzed cross-coupling reactions, olefin arylation reactions as well as some carbonylation p r o c e ~ s e s . ~ Bromoarenes are appreciably less reactive substrates in all of these reactions. The cheapest haloarenes, chlorobenzenes, are much more inert and are usually incapable of undergoing reactions observed with iodoarenes and bromoarenes. Recently, carbonylation reactions of chloroarenes have been discovered by the use of novel palladium complexes as catalysts.' The low chemical reactivity of the aryl carbon-chlorine bond can be rationalized on the basis of kinetic and thermodynamic (1) Mundy, B. P.; Ellerd, M. G. Name Reactions and Reagents in Organic Synthesis; Wiley: New York, 1988. (2) Roesi, R.A.; de Roeei, R. H. Aromatic Substitution by the S,l Mechanism; American Chemical Society: Waehington, DC, 1983. (3) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles and Application of OrganotransitionMetal Chemistry;University Science Books: Mill Valley, CA, 1987. (4) (a) Ben-David, Y.; Portnoy, M.; Milstein, D., J . Am. Chem. SOC. 1989,111,8742. (b) Jhfaud, V.; Thiroll-Carat,J.; Basset, J. M. J. Chem. SOC.,Chem. Commun. 1990, 426, and references cited therein.
(DPhxl = 96 kcal/m01)~factors. Phase-transfer catalysis (PTC)has been widely used in the synthesis of organometallic complexes and for transition-metal-catalyzed organic reactions! Recently, PTC was shown to be effective for the generation of electron-rich and coordinatively unsaturated transition-metal complexes by reductive elimination of hydrogen chloride from some hydrido transition-metal chlorides (eq l).7For example,
the rhodium hydrides [(Cy3P)2Rh(H)C12](Cy = cyclohexyk 1) and [(i-Pr3P),Rh(H)C12] (i-Pr = isopropyl; 2), in the presence of KOH or NaOH, are able to catalyze H/Dexchange between dihydrogen and aromatic hydrocarbons? (5) Cox, J. D.; Pilcher, G. Thermochemistry of Organic and Organometallic Compounds;Academic Press: London, 1970. (6) (a) Alper, H. Adu. Organometal. Chem. 1981,19,183. (b)Caeear, L.Ann. N.Y. Acad. Sci. 1980,333,208. (c) Alper, H. Fund. Res. Homogen. Catal. 1984, 4, 79. (d) Petrignani, J. F. The Chemistry of the Carbon-MetalBond; Hartley, F. R. Ed.:Wiley: New York, 1989 Vol. 5, pp 63-106. (7) (e) Gruehin, V. V.; Akhrem, I. S.; Vol'pin, M. E. Metalloorgan. Khim. 1988,1,474; J. Organometol. Chem. 1989,371,403. (b)Gruahin, V. V.; Vymenits, A. B.; Vol'pin, M. E. J. Organometal. Chem. 1990,362, 185. (c) Gruahm, V. V.; Vymenits, A. B.; Yanowky, A. I.; Struchkov, Yu. T.; Vol'pin, M. E. Organometallics 1991, 10, 48.
0276-7333/91/2310-l620$02.50/00 1991 American Chemical Society
Organometallics, Vol. 10, No. 5, 1991 1621
Hydrogenolysis of Chloroarenes
Table I. Hydrogenolyeis of Chloroarenes by Ht/l/PhCH2N(C2HI)8+C1-/40% NaOH chloroarene (amt, mmol) chlorobenzene (1.4) 1-chloronaphthalene (10) 4-chlorotoluene (10) 3-chlorotoluene (10) 2-chlorotoluene (10) 4-chloroaniline (2) 4-chloroanisole (10)
amt of PhCH,, mL 1.0 1.0
1, mol %
5 1 1 1
1
3-chlorobenzophenone (5)
1.5
5 1 1 2
p-chlorobenzoic acid (2) p-(chloropheny1)acetic acid (2) carprofen (0.37) 5-chlorobenzodioxole (1.05)
3.0 1.0 2.0 1.0 1.0 1.0
5 5 10 10 5 20
4-chloro(trifluoromethyl)benzene(10)
5-chloro-1-ethyl-2-methylimidazole (2.1) tetrachloro-m-xylene(0.5)
1.0
T,'C 25 85 60 60 60 95 80 60 50 90 90 90 90 80 100
time, h 24 5 19 20 18 19 9.5 18 3 25 21 24 48 8 48
product benzene naphthalene toluene toluene toluene aniline anisole (trifluoromethy1)benzene benzophenone benzhydrol benzoic acid phenylacetic acid
a-methyl-9H-carbazole-2-acetic acid benzodioxole
1-ethyl-2-methylimidazole 2-chloro-m-xylene
yield: % (97) 92 (97) (95) (7) 80 (91) 60 (99) 87 97
