[25136-46-3]  · C54H45NiP3  · Tris(triphenylphosphine)nickel(0)  · (MW 845.59)

(a source of nickel(0) useful for the coupling of aryl, alkenyl, and allyl halides;2 oligomerization of strained alkenes;3 oligomerization of allenes4)

Physical Data: mp 124-126 °C (N2).

Solubility: sol toluene, benzene, DMF, DMA, Et2O, THF, HMPA.

Analysis of Reagent Purity: 1H NMR d 7.37 (o-H), 6.96 (m- and p-H).5

Preparative Methods: the standard preparation involves the reduction of Nickel(II) Chloride with Zinc dust in the presence of Triphenylphosphine. Anhydrous NiCl2 (2.6 g) was refluxed with 21 g of PPh3 in 300 mL of acetonitrile for 1 h. After cooling to rt, 2.0 g of zinc dust was added and the mixture was stirred under nitrogen overnight. After removal of solvent, the resulting red solid was dissolved in the minimum volume of hot toluene (60 °C), removed from insoluble impurities by hot filtration, precipitated by the addition of hexane, and dried under vacuum to give a reddish-brown powder.5 This precipitation has also been carried out in situ from the same starting materials and is currently the favored procedure.2 Several other methods of preparation have been described.6

Handling, Storage, and Precautions: highly oxygen sensitive; special inert-atmosphere techniques must be used.7 Should be stored at 0 °C.

Coupling of Aryl, Alkenyl, and Allyl Halides.

Tris(triphenylphosphine)nickel(0) reacts with organic halides by oxidative addition of nickel(0) into carbon-halogen bonds to form intermediate nickel(II) complexes.8 These organometallic intermediates, which are usually not isolated, react with a variety of nucleophiles, leading to replacement of the original halide with the nucleophile and regeneration of a catalytic nickel(0) species. In the case of aryl halides, the arylnickel intermediates can be reacted with cyanide salts to give nitriles,9 with acetylides to give alkynes,10 with halide salts to give halogen exchange,11 with phosphines to give phosphonium salts,12 and with sodium borohydride to give overall hydrogenation.13 Aryl amines, ethers, and carboxylic acids have also been formed catalytically through these types of reactions.14 Aryl bromides and iodides both work well as substrates, and many functional groups are tolerated. However, ortho substituents tend to slow the reactions down and give lower yields. A wide array of cross-coupling reactions with Grignard and other organometallic reagents have also been performed, but using Ni(PPh3)4 as the catalyst.

Homocoupling of aryl halides requires stoichiometric amounts of nickel(0), but can be made catalytic in nickel by the addition of excess zinc, magnesium, or manganese as a reducing agent.15 Aryl chlorides are reactive for this transformation and the yields of biphenyls from para-substituted aryl chlorides are better than in the corresponding stoichiometric reactions (eq 1).16 Nitro groups destroy the catalytic acivity of the nickel complexes,17 and ortho substituents strongly inhibit the reaction. The presence of acidic functionalities leads to reduction of the arene. A macrocyclic bicycle, bis[18]annulene, was synthesized by this method.18 This coupling reaction has also been carried out intramolecularly to produce a macrocyclic pentaphenylene in 65% yield.19

In the case of alkenyl halides, oxidative addition of the nickel(0) catalyst occurs with retention of configuration of the double bond.20 This reaction has been used for the homocoupling of vinyl bromides,21 and to make dienoic acids by the insertion of 3-butenoic acids.22 Allylic halides may be homocoupled as well.2

The coordinatively unsaturated Ni(PPh3)3 catalyst is also formed in solution from Ni(PPh3)4 by ligand dissociation and is probably the reactive species in oxidative addition reactions of Ni(PPh3)4 (see Tetrakis(triphenylphosphine)nickel(0) and Bis(1,5-cyclooctadiene)nickel(0)).23

Oligomerization of Strained Alkenes.

3,3-Disubstituted cyclopropenes dimerize with catalytic Ni(PPh3)3 via a [2 + 2] cycloaddition pathway to form cyclobutanes.24 Methylenecyclopropane reacts to give mixtures of cyclic and acyclic dimers and trimers (see Bis(1,5-cyclooctadiene)nickel(0)).25

Oligomerization of Allenes.

Substituted allenes react with Ni(PPh3)3 to form dimers and trimers.26 When carbon monoxide is added, CO insertion leads exclusively to cyclic products.4 Reaction with a diallene, 2,7-dimethyl-2,3,5,6-octatetraene, quantitatively produced a 10-membered ring trimer (see also Bis(triphenylphosphine)nickel(0)).27

1. Jolly, P. W.; Wilke, G. The Organic Chemistry of Nickel; Academic: New York, 1974/1975; Vols. I and II.
2. Jolly, P. W. In Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., Eds.; Pergamon: New York, 1982; Chapter 56.5, p 713.
3. (a) Jolly, P. W. In Comprehensive Organometallic Chemistry; Wilkinson, G.; Stone, F. G. A.; Abel, E. W., Eds.; Pergamon: New York, 1982; Chapter 56.2, p 615. (b) Binger, P.; Büch, M. Top. Curr. Chem. 1987, 135, 77.
4. Pasto, D. J.; Huang, N-Z.; Eigenbrot, C. W. JACS 1985, 107, 3160.
5. Tollman, C. A.; Seidel, W. C.; Gerlach, D. H. JACS 1972, 94, 2669.
6. (a) Dick, D. G.; Stephan, D. W.; Campana, C. F. CJC 1990, 68, 628. (b) Heimbach, P. AG(E) 1964, 3, 648.
7. Shriver, D. F. The Manipulation of Air-Sensitive Compounds; McGraw-Hill: New York, 1969.
8. (a) Foà, M.; Cassar, L. JCS(D) 1975, 23, 2572. (b) Pearson, R. G.; Figdore, P. E. JACS 1980, 102, 1541.
9. (a) Cassar, L.; Foà, M.; Montanari, F.; Marinelli, G. P. JOM 1979, 173, 335. (b) Sakakibara, Y.; Okuda, F.; Shimobayashi, A.; Kirino, K.; Sakai, M.; Uchino, N.; Takagi, K. BCJ 1988, 61, 1985.
10. Cassar, L. JOM 1975, 93, 253.
11. Takagi, K.; Hayama, N.; Inokawa, S. BCJ 1980, 53, 3691.
12. Cassar, L.; Foà, M. JOM 1974, 74, 75.
13. Lin, S-T.; Roth, J. A. JOC 1979, 44, 309.
14. Cramer, R.; Coulson, D. R. JOC 1975, 40, 2267.
15. (a) Zembayashi, M.; Tamao, K.; Yoshida, J-I.; Kumada, M. TL 1977, 4089. (b) Colon, I.; Kelsey, D. R. JOC 1986, 51, 2627 and references therein.
16. See Refs. 21 and 15(b).
17. Negishi, E-i.; King, A. O.; Okukado, N. JOC 1977, 42, 1821.
18. Storie, I. T.; Sondheimer, F. TL 1978, 4567.
19. Fujioka, Y. BCJ 1984, 57, 3494.
20. Cassar, L.; Giarrusso, A. G 1973, 103, 793.
21. Kende, A. S.; Liebeskind, L. S.; Braitsch, D. M. TL 1975, 3375.
22. Chiusoli, G. P.; Salerno, G.; Giroldini, W.; Pallini, L. JOM 1981, 219, C16.
23. (a) Tollman, C. A. JACS 1970, 92, 2956. (b) Tolman, C. A.; Seidel, W. C.; Gosser, L. W. JACS 1974, 96, 53.
24. (a) Peganova, T. A.; Petrovskii, P. V.; Isaeva, L. S.; Kravtsov, D. N.; Furman, D. B.; Kudryashev, A. V.; Ivanov, A. O.; Zotova, S. V.; Bragin, O. V. JOM 1985, 282, 283. (b) Isaeva, L. S.; Peganova, T. A.; Petrovskii, P. V.; Kravtsov, D. N. JOM 1989, 376, 141. (c) Furman, D. B.; Rudashevskaya, T. Y.; Kudryashev, A. V.; Ivanov, A. O.; Isaeva, L. S.; Morozova, L. N.; Peganova, T. A.; Bogdanov, V. S.; Kravtsov, D. N.; Bragin, O. V. BAU 1990, 287.
25. (a) Binger, P.; Brinkman, A.; McMeeking, J. LA 1977, 1065. (b) Furman, D. B.; Ivanov, A. O.; Kudryashev, A. V.; Morozova, L. N.; Peganova, T. A.; Petrovskii, P. V.; Isaeva, L. S.; Kravtsov, D. N.; Bragin, O. V. BAU 1989, 892.
26. Pasto, D. J.; Huang, N-Z. OM 1985, 4, 1386.
27. Pasto, D. J.; Huang, N-Z. JOC 1985, 50, 4465.

Paul A. Wender & Thomas E. Smith

Stanford University, CA, USA

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