Tetrakis triphenylphosphine nickel

The material may be purified by extraction at 60° with 150 mL of benzene containing 10 g of triphenylphosphine. The benzene is removed on a rotary evaporator while n-heptane is added to keep the mixture at constant volume. The precipitated product is collected and washed with two 20-mL portions of diethyl ether. 

This procedure is useful for the preparation of the compounds listed in Table II as well as many others where the ligands are solids and possibly insoluble in the reaction solvent. All of the preparations are on a scale which starts with 10.0 g of Ni(C8H12)2. The quantities of various ligands for each complex are listed, as is the preferred solvent for the reaction. Colors and melting points are included for characterization. 

Compound Ligand I Ligand II Solvent Color mp, °C Calcd. Found Calcd. Found 

All the compounds in Table II are soluble in aromatic solvents. They are all moderately air-sensitive, and the arsine and stibine complexes are thermally unstable, decomposing upon standing in solution—or more slowly in the solid state—to liberate nickel metal. 

Azobenzenet (6.7 g, 36 mmol) in ether (50 mL) is injected into the dropping funnel and is allowed to flow into flask A during the next 5 min. The mixture is stirred for 30 min and then filtered. The red, air-sensitive product is washed with two 20-mL portions of hexane and dried in vacuo. The yield is almost quantitative. Recrystallization from diethyl ether results in red needles which decompose at 162° (v(C=N) = 2168, 2140 cm-1). Anal. Calcd. for C22H2N4Ni C, 64.8 H, 6.9 N, 13.7. Found C, 64.6 H, 7.0 N, 13.6. 

This synthesis is an alternative to the procedure given earlier. If Ni[P(C6H5)3]4 is the only zero-valent nickel complex desired, the earlier synthesis will be preferred but if Ni(l,S-cod)2 is available or if several different nickel complexes are desired, this method will be superior. 

This procedure is based on that previously described by Wilke.1 The use of NaBH4 and sodium naphthalide as reducing agents has been more recently reported by Ugo.2 

The complex rapidly decomposes upon exposure to air either as a solid or in solution. It is very soluble in benzene, toluene, and tetrahydrofuran, slightly soluble in diethyl ether, and only very slightly soluble in n-heptane and ethanol. 

For discussion of general manipulative techniques useful in this work, see D. F. Shriver, The Manipulation of Air-sensitive Compounds, chap. 7, McGraw-Hill Book Company, New York, 1969. 

The use of hydrated bis(2,4-pentanedionato)nickel decreases the yield to ca. 25%. N CsHvChVzHjt) was dehydrated by boating at 1()()°/0.1 mm./2 hours followed by recrys- 

Triethylaluminum reacts violently with water and inflames in air. Care must also be taken in preparing the diethyl ether solution since an exothermic reaction occurs the ether solution is conveniently transferred to the addition funnel via a hypodermic syringe. 

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Although the copper mediated Ullmann reaction is a well known method for biaryl synthesis, drastic conditions in the range of 150-280 °C are required. Zerovalent nickel complexes such as bis(l,5-cyclooctadiene)nickel or tetrakis(triphenylphosphine)nickel have been shown to be acceptable coupling reagents under mild conditions however, the complexes are unstable and not easy to prepare. The method using activated metallic nickel eliminates most of these problems and provides an attractive alternative for carrying out aryl coupling reactions(36,38). 

Dialkylindolines and 1,3-dialkylindoles are formed in poor yield (<10%) from the reaction of ethyl- or phenymagnesium bromide with 2-chloro-N-methyl-N-allylaniline in the presence of catalytic quantities of (bistriphenylphosphine)nickel dichloride.72 In a modification of this procedure, the allyl derivatives can be converted by stoichiometric amounts of tetrakis(triphenylphosphine)nickel into 1,3-dialkylindoles in moderate yield72 (Scheme 43) an initial process of oxidative addition and ensuing cyclization of arylnickel intermediates is thought to occur. In contrast to the nickel system,72 it has proved possible to achieve the indole synthesis by means of catalytic quantities of palladium acetate.73 It is preferable to use... 

Nickel(II) catalysts with a direct nickel(II)-polystyrene bond have been prepared by oxidative addition of tetrakis(triphenylphosphine) nickel(O) to brominated polystyrene (58) ... 

Cy anotrimethy I si 1 anc. Methanesulfony I chloride. N-Methylpyrrolidone. Nitroethane-Pyridinium chloride. Sodium cyanide-Chlorotrimethylsilanc. Tetrakis(triphenylphosphine)nickel. 

Palladium-catalyzed carbonylation of aryl triflates in the presence of an alcohol141 or amine1423 provides a good method for preparation of arenecarboxylic esters and amides from phenols (equation 121). However, palladium-catalyzed cyanation of 5,6,7,8-tetrahydro-2-naphthyl triflate with potassium cyanide failed completely whereas the more reactive tetrakis(triphenylphosphine)nickel(0) could catalyze the same reaction which gives the nitrile in a good yield142b (equation 122). 

Tetrakis(triphenylphosphine)nickel(0), [(C6Hs)3P]4Ni. Mol. wt. 1107.89, reddish brown sohd, m.p. 123-128°. The complex decomposes rapidly upon exposure to air as a soUd or in solution. 

Polyfluoroalkyl iodides react regioselectively with furan to form 2-polyfluoroalkyl derivatives in the presence of catalytic amounts of tetrakis(triphenylphosphine) nickel at 60-80° C. 

Zhou, Q.L. Huang, YZ. Direct fluoroalkylation of aromatic compounds catalyzed by tetrakis(triphenylphosphine)nickel. J. Fluorine Chem. 1989, 43, 385-392. 

Alkynylzinc chlorides are readily available by treatment of lithium acetylide (6, 324) or an ethynyllithium with anhydrous zinc chloride in THF. Tetrakis-(triphenylphosphine)nickel(O) (6, 570) is a much less efficient catalyst than the Pd(0) system. Dienes and diynes are formed in only traces (<5%). 

Tetrakis(triphenylphosphine)nickel(0), 357 Tetrakis(tripbenylphosphine)palladium(0), 95, 357-358 Tetralones, 327... 

Comparatively few compounds exist which contain organophosphine groups as the sole ligands and some of these are rather unstable. Thus at room temperature tetrakis (triphenylphosphine) nickel is substantially dissociated to Ni(PPh3)j, and the platinum derivative is likewise dissociated in solution. 

In conclusion, oxidative addition of aryl halides to metallic nickel proceeded smoothly under mild conditions, and the corresponding biaryls were obtained in good yields. The present reaction is superior to the Ullmann synthesis in the scope of the reaction conditions [125] and to the coupling reaction of Grignard reagents catalyzed by transition metals [133]. Finally, because of the simple and easy procedure for the preparation of nickel powder, it is far more convenient to work with than zerovalent nickel complexes such as tetrakis(triphenylphosphine)nickel(0) or bis(l,5-cyclooc-tadiene)nickel(O) [128]. 

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