O-Tolyl phosphite

The formation of cationic nickel hydride complexes by the oxidative addition of Brdnsted acids (HY) to zero-valent nickel phosphine or phosphite complexes (method C,) has already been discussed in Section II. Interesting in this connection is a recent H NMR study of the reaction of bis[tri(o-tolyl)phosphite]nickelethylene and trifluoroacetic acid which leads to the formation of a square-planar bis[tri(o-tolyl)phosphite] hydridonickel trifluoroacetate (30) (see below) having a cis arrangement of the phosphite ligands (82). 

Gosser, L.W. and Tolman, C.A. (1970) New three-coordinate complex of nickel (0). Tris(tri-o-tolyl phosphite)nickel. Inorg. Chem., 9, 2350. 

Tolman, C.A. (1974) Olefin complexes of nickel(0). III. Formation constants of (olefin)bis(tri-o-tolyl phosphite) nickel complexes. /. Am. Chem. Soc., 96, 2780. 

The use of tris(o-tolyl) phosphite in place of triphenylphosphine has been found to favour the reductive coupling of the metal-coordinated methylallyl (or of the cyanobutyl group in the second step) with the CN group, which liberates the metal in its original (0) oxidation state. 

B. ETHYLENEBIS(TRICYCLOHEXYLPHOSPHINE)PALLADIUM(0) AND ETHYLENEBIS(TRI-o-TOLYL PHOSPHITE)PALLADIUM(O)... 

Both bis(l,5-cyclooctadiene)nickel(0) and bis(acrylonitrile)nickel(0) catalyze the polymerization of allene to highly crystalline linear polymers (451). With compounds such as tri-o-tolyl phosphite, bis(acrylo-nitrile)nickel in hydrocarbon catalyzes the cyclodimerization of butadiene to 1,5-cyclooctadiene, whereas in alcohols it catalyzes the... 

Tris(tri-o-tolyl phosphite)nickel(O),4 likewise a useful catalyst,5 is conveniently prepared by displacement of ethylene from the olefin complex by a mole of phosphite ligand as described in Sec. B. Alternatively, it can be prepared directly by reduction of hydrated nickel nitrate with sodium tetrahydroborate in acetonitrile (Sec. C). This method avoids the need to handle spontaneously flammable triethylaluminum. 

A solution of 10.0 g. (12.6 mmoles) of ethylenebis(tri-otolyl phosphite)nickel(0) and 4.4 g. (3.9 ml.) of tri-otolyl phosphite in 50 ml. of benzene is evaporated to dryness under vacuum. Nitrogen is admitted to the flask, and the resulting red foam is dissolved in 75 ml. of toluene. The tris(tri-o-tolyl phosphite)nickel is precipitated as red crystals by addition of 150 ml. of methanol and cooling yield 12 g. (85%). The checker obtained an 88% yield of product,... 

Sodium tetrahydroborate, nickel nitrate hexahydrate, and nominally anhydrous acetonitrile are commercially available. Tri-o-tolyl phosphite is prepared by the method of Walsh.6... 

Tris(tri-o-toIyI phosphite)nickel(O) is a bright red-orange solid which decomposes above ca. 125-140°. The 407-nm. peak has e = 5.0 x 103 cm.-1 M 1 and the 450-nm. shoulder has e = 3.7 x 103 cm.-1 M-1. The n.m.r. signal of the methyl hydrogens in free tri-o-tolyl phosphite is at 2.11 p.p.m. down field from internal tetramethylsilane in benzene solution, while the methyl resonance of coordinated tri-o-tolyl phosphite is only 1.96 p.p.m. down field. 

The prq>aTatioa of NiC3F2CFssCF2CF2 P(0-o-tolyl)3 2 (138) from C2F4 and tris(tri-o-tolyl phosphite)nickel under conditions where other olefins give three-... 

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