Nickel tris complexes

The first polyphosphino maeroeyeles designed speeifieally for use as transition metal binders were reported in 1977 in back-to-baek eommunications by Rosen and Kyba and their eoworkers. The maeroeyeles reported in these papers were quite similar in some respeets, but the synthetic approaches were markedly different. DelDonno and Rosen began with bis-phosphinate 18. Treatment of the latter with Vitride reducing agent and phosphinate 19, led to the tris-phosphine,20. Formation of the nickel (II) complex of 20 followed by double alkylation (cyclization) and then removal of Ni by treatment of the complex with cyanide, led to 21 as illustrated in Eq. (6.15). The overall yield for this sequence is about 10%. 

Nickel, tris(l, 10-phenanthroline) racemization, 1,24. 466 solid state, 1, 467 structure, 1,64 Nickel complexes, 5,1-300 acetylacetone alcoholysis, 2, 380 pyridine complexes, 2, 386 solvolysis, 2,379 structure, 2,388 amidines... 

Nickel and palladium react with a number of olefins other than ethylene, to afford a wide range of binary complexes. With styrene (11), Ni atoms react at 77 K to form tris(styrene)Ni(0), a red-brown solid that decomposes at -20 °C. The ability of nickel atoms to coordinate three olefins with a bulky phenyl substituent illustrates that the steric and electronic effects (54,141) responsible for the stability of a tris (planar) coordination are not sufficiently great to preclude formation of a tris complex rather than a bis (olefin) species as the highest-stoichiometry complex. In contrast to the nickel-atom reaction, chromium atoms react (11) with styrene, to form both polystyrene and an intractable material in which chromium is bonded to polystyrene. It would be interesting to ascertain whether such a polymeric material might have any catal3dic activity, in view of the current interest in polymer-sup-ported catalysts (51). 

Nickel(0) complexes with water-soluble phosphines have attracted interest in the context of homogeneous catalysis. A comprehensive study of the coordination chemistry of tris(sodium-m-sulfonatophenyl)phosphine (1039) has appeared.2504 The complexes [Ni(CO)2(1039)2] 6HzO have been made by reaction of (1039) with Ni(CO)4 under phase-transfer conditions, and the homo-leptic [Ni(1039)3]-9H2O has been made from Ni° precursors and (1039) under phase-transfer conditions, or from NiCl2, (1039), and BH4 in water. A related complex [Ni(CO)2(1040)2] with the bidentate ligand (1040) has also been studied.2505... 

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). 

Other reactive forms of nickel including nickel boride and nickel alkoxide complexes can also be used for desulfurization. Tri-w-butyltin hydride is an alternative reagent for desulfurization.204... 

The monomers dealt with can be polymerized by various mechanisms, not only by ROMP. For example, a rapid polymerization of norbornadiene occurs using a homogeneous catalytic system consisting of nickel acetylacetonate or a nickel-phosphine complex, such as nickel bis-(tri-n-butylphosphine) dichloride (NiCl2(TBP)2) or nickel bis-(tricyclohexylphosphine) dichloride (NiCl2(TBP)2). Nickel acetylacetonate as catalyst is known to initiate rather a classical vinyl polymerization (7). The classical vinyl polymerization... 

The ligands tris(2-pyridylmethyl)amine (tpma), tris(3,5-dimethyl-l-pyrazolylmethyl)amine (metpyma) and tris(3,5-dimethyl-l-pyrazolylethyl)amine (metpyea) are examples of tetraden-tate tripod-shaped ligands containing three heterocyclic nitrogen donors connected to an apical tertiary nitrogn donor by.aliphatic chains. Selected nickel(II) complexes with these ligands are reported in Table 50. 

Many types of ligand have been designed or are known to favour the formation of di- and tri-nuclear nickel complexes. This field of coordination chemistry has recently been extensively reviewed.2590,2591 For a specific discussion of the magnetic properties of dinuclear nickel(II) complexes, see Section 50.5.10. 

The structures determined by X-ray analysis of the complexes [Ni(Me3[12]eneN3)2](NCS)2 (Me3[12]eneN3 = 2,4,4-trimethyl-l,5,9-triazacyclododec-l-ene) and [Ni(TRI)(H20)N03]N03 (TRI = tribenzo[b,/,/][l,5,9]triazacyclododecane) show that the two triaza macrocycles coordinate facially in both square pyramidal2721 and octahedral complexes.2724 Other complexes with triaza macrocycles have been prepared and are assumed to be either live- or six-coordinate.2721-2725 Selected examples of nickel(II) complexes with unsaturated macrocydes are reported in Table 106. 

In the present article we will not try to give an exhaustive compilation of nickel(III) and nickel(IV) complexes due to the large amount of work which is currently being undertaken in the field. Particular attention will be placed on those complexes whose properties have been investigated with the largest number of experimental techniques to have a better description of the electronic and geometrical structure of the compounds. 

One of the most spectacular and useful template reactions is the Curtis reaction , in which a new chelate ring is formed as the result of an aldol condensation between a methylene ketone or inline and an imine salt. The initial example of this reaction was the formation of a macrocyclic nickel(II) complex from tris(l,2-diaminoethane)nickel(II) perchlorate and acetone (equation 53).182 The reaction has been developed by Curtis and numerous other workers and has been reviewed.183 In mechanistic terms there is some circumstantial evidence to suggest that the nucleophile is an uncoordinated aoetonyl carbanion which adds to a coordinated imine to yield a coordinated amino ketone (equation 54). If such a mechanism operates then the template effect is largely, if not wholly, thermodynamic in nature, as described for imine formation. Such a view is supported by the fact that the free macrocycle salts can be produced by acid catalysis alone. However, this fact does not... 

The nickel-catalyzed transformation of aromatic halides into the corresponding nitriles by reaction with cyanide ions is reported. Both tris(triarylphosphine)nickel(0) complexes and tY2ins-chloro( aryl )bis( triarylphosphine )nickel(II) complexes catalyze the reaction. The influence of solvents, organophos-phines, and substituents on the aromatic nucleus on catalytic cyanation is studied. A mechanism of the catalytic process is suggested based on the study of stoichiometric cyanation of ti3ins-chloro(aryl)bis(triphenylphosphine)nickel-(II) complexes with NaCN and the oxidative addition reaction of Ni[P(C6H5)3]s with substituted aryl halides. 

Tris (triphenylphosphine) nickel, tris (tri-p-tolylphosphine) nickel, and bis (1,3-diphenylphosphinepropane) nickel proved to be good catalysts, the first being slightly more effective. The tricyclohexylphosphine complex was a very poor catalyst, and bis (cyclooctadiene) nickel did not catalyze cyanation. Cyanation of several substituted aromatic halides in the presence of Ni[P(C6H5)3]3 prepared by reducing dichlorobis (triphenylphosphine) nickel (II) 2 with a powdered manganese iron (80 20) alloy (Reaction 3) is reported in Table II. 

The phenomenon of spin equilibrium in octahedral complexes was first reported by Cambi and co-workers in a series of papers between 1931 and 1933 describing magnetic properties of tris(iV,iV-dialkyldithio-carbamato)iron(III) complexes. By 1968 the concept of a thermal equilibrium between different spin states was sufficiently well established that the definitive review by Martin and White described the phenomenon in terms which have not been substantially altered subsequently (112). During the 1960s the planar-tetrahedral equilibria of nickel(II) complexes were thoroughly explored and the results were summarized in comprehensive reviews published by Holm and coworkers in 1966 and 1973 ( 79, 80). Also, in 1968, Busch and co-workers... 

The earliest high-oxidation-state complex of nickel reported was the heteropoly(molybdate) (132, 133) complex [NilvMo90 32]6. which contains nickel(IV) in an octahedral Ni06 coordination environment. There is no evidence for the corresponding nickel(III) species but further work on nickel(IV) complexes of this type has been reported recently (134). Nickel(III) can be prepared in a six-coordinate oxygen donor environment (135) as a tris chelate with 2,2 -bipyridine-l,T-dioxide (bpy02). The complex has a rhombic EPR spectrum and a reduction potential of 1.7 V, from which an estimate of the reduction potential of the ion [Nini(H20)6]3+ of 2.5 V (versus nhe) has been calculated. 

Treatment with the nickel(II) complex of the tripeptide glycine-glycine-histidine in the presence of magnesium monoperoxyphthalate Visible light irradiation in the presence of tris(bipyridyl)ruthenium(II) dication and ammonium persulfate Ethylmercury phosphate Fluorescein... 

Some iron and nickel cyanide and carbonyl complexes have been reported as models of the [FeNi]-hydrogenase enzymes. The preparation and structures of the trigonal bipyramidal nickel and iron complexes with the tetradentate ligands tris(2-phenylthiol)phosphine (PS3) and tris(3-phenyl-2-thiophenyl)phosphine (PS3 ) have been reported [70, 71]. The nickel carbonyl complex [Ni(PS3 )(CO)] exhibits vco at 2029 cm compared with the value of 1940 em" for the iron earbonyl complex [Fe(PS3 )(CO)]. Both of these complexes lose CO upon oxidation. The use of cyanide in place of carbon monoxide allows for the preparation of both [Fe (PS3)(CN)] and [Fe (PS3 )(CN)] eomplexes. The IR properties of... 

---