Arsine complexes nickel

The corresponding palladium compound (157) must be formulated as [Pd(TA)Br]+Br. The cation is essentially square-planar, but the bromine atom is displaced 10° out of the arsenic-palladium plane. Such a distortion is very unusual for palladium, and may be due to a steric effect of the alkyl chains in the arsine ligand. This might similarly account for the distortion of the nickel complex from a square pyramidal shape. 

Table 3 Summary of Nickel Complexes with Phosphines, Arsines and Stibines, and their Methods of Synthesis...

Even if the C104 ion is commonly believed to experience a scarce tendency to act as a ligand, nonetheless coordination of perchlorate as a monodentate ligand through an oxygen atom has been proposed in a number of nickel complexes containing alkylamines,1676 pyridine and substituted pyridines,1677-1680 arylamines such as aniline and substituted anilines,1681 phosphine and arsine oxides1682,1683 (Table 84). 

Unlike the tertiary phosphine and arsine oxides which form a variety of nickel complexes with peculiar properties, tertiary arsine sulfides and, particularly, tertiary phosphine sulfides... 

The iron compound readily sublimes and yields well-formed, black lustrous crystals. The cobalt complex will also readily sublime, but dependent upon the temperature at which the crystals are formed, they can be either black or brown in color. The crystal structures of both the cobalt and iron complexes have been determined.3 The nickel complex sublimes only in small amounts with difficulty. All three complexes are unstable to air and water, and the nickel complex readily undergoes thermal decomposition above 100°C. All three compounds will also readily form complexes with a variety of donor ligands such as tertiary arsines or phosphines. The nickel compound usually forms 2 1 adducts such as [(C6HS )3P]2Ni(NO)I, while the iron and cobalt complexes often undergo disproportionation.5... 

AsFe04C22H,5, lron(0), tetracarbonyl(tri-phenylarsine)-, 26 61, 28 171 AsjCijHij, Arsine, l,2-phenylenebis(di-methyl-, gold complex, 26 89 nickel complex, 28 103 AsjCljNRuSCjgHjo, Ruthenium(II), tri-... 

Nickel, diacetylbis(benzoylhydrazonato)-, 203 Nickel complexes, 1-300 T] -bonded, 33 arsenic sulfide, 36 arsines, 34 CjPhj, 33... 

C10H15N, Benzenemethanamine, N,N,4-trimethyl-, lithium complex, 26 152 C10H15P, Phosphine, diethylphenyl-, nickel complex, 28 101 platinum complex, 28 135 CioHigAsi, Arsine, 1,2-phenylenebis(dimethyl-, gold complex, 26 89 nickel complex, 28 103 CioHie, 1,3-Cyclopentadiene, 1,2,3,4,5-pen-tamethyl-, 28 317 chromium complex, 27 69 cobalt complexes, 28 273, 275 iridium complex, 27 19 samarium complex, 27 155 titanium complex, 27 62 ytterbium complex, 27 148 CioH,gBrN04S, Bicyclo[2.2.1]heptane-7-methanesulfonate, 3-bromo-1,7-di-methyl-2-oxo-, U.IRHENDO, ANTPi]-, ammonium, 26 24... 

The precise mechanism of many oligomerization reactions remains open to discussion. We have already mentioned the question of whether cyclodimerization of butadiene, catalysed by nickel complexes, is a concerted or a stepwise process, of polymerization and then cyclization. The cyclo-trimerization of alkynes is often thought to proceed by co-ordination of three alkyne molecules to the metal catalyst, with a subsequent concerted cyclization step. Recent studies of the cyclotrimerization of hexafluorobut-2-yne in the presence of Ni(cod)j or of arsine complexes, however, suggest a stepwise process in which an intermediate (67) is formed, to which... 

Although trialkyl- and triarylbismuthines are much weaker donors than the corresponding phosphoms, arsenic, and antimony compounds, they have nevertheless been employed to a considerable extent as ligands in transition metal complexes. The metals coordinated to the bismuth in these complexes include chromium (72—77), cobalt (78,79), iridium (80), iron (77,81,82), manganese (83,84), molybdenum (72,75—77,85—89), nickel (75,79,90,91), niobium (92), rhodium (93,94), silver (95—97), tungsten (72,75—77,87,89), uranium (98), and vanadium (99). The coordination compounds formed from tertiary bismuthines are less stable than those formed from tertiary phosphines, arsines, or stibines. 

The most common nickel(O) complexes are those containing phosphorus, arsenic and antimony as donor atoms. Besides the Malatesta and Cenini book/1 which specifically deals with metal(O) complexes, nickel(O) complexes have been summarized in books and review articles which report complexes with phosphine, arsine and stibine ligands.31-37 Actually the nickel(O) complexes with these ligands amount to hundreds and the number of new complexes which are synthesized is increasing very rapidly, making nickel(0) phosphine chemistry a very extensive topic. 

Several synthetic procedures have been developed for the preparation of complexes with phosphines, arsines and stibines, and the most convenient or historically important ones are summarized in Table 3. They can be grouped in three main types of reaction the direct reactions of nickel with ligands, ligand replacement reactions and reduction reactions of nickel(H) complexes. 

The reaction of fluoroalkenes with nickel(O) phosphine and arsine complexes may also result in the dimerization of the fluoroalkene and in the formation, for example, of octafluoro-nickelacyclopentane complexes [Ni(ER3)2(CF2)4] (E = P, As), which contain the nickel atom in the formal oxidation state +2., 55 A similar reaction also occurs when [N PPhj QtFj reacts... 

Nickel(I) complexes are far less numerous than those of nickel(0). Like nickel(0) complexes, nickel(I) complexes are generally obtained with ligands having -acceptor capability. Most complexes of nickel(I) which have been isolated as solids contain tertiary phosphines (or arsines) as ligands and are sufficiently stable in the absence of air to allow them to be studied with several physicochemical techniques. 

Most of the nickel(l) complexes are four-coordinate, either tetrahedral (phosphine and arsine complexes) or square planar (macrocyclic and dithiolene complexes), but five-coordinate complexes are also easily formed in the presence of tetradentate tripodal ligands. 

Selected nickel(I) complexes with phosphines and arsines, together with relevant properties and synthetic routes, are reported in Table 21. In general, these nickel(I) complexes are air-unstable, especially when dissolved in solution consequently their preparation and handling require the exclusion of oxygen and, often, of moisture. The synthetic routes which afford nickel(I) complexes are strictly dependent on the nature of the phosphines and arsines and are not of general application, except in the case of some tripodal ligands. Most of the nickel(I)... 

Table 21 Summary of Synthetic Procedures and Properties of Nickel(I) Complexes with Phosphines and Arsines... 

The number of nickel(U) complexes with mono-, bi- and poly-dentate ligands containing tertiary phosphines as a donor group is very large and increases day by day while complexes with tertiary arsines are less numerous and those with stibines are rarer still. The number of nickel(II) complexes with mixed donor ligands containing N, O and S donor atoms besides P or As is also very large. 

A large number of nickel(II) complexes with bidentate tertiary phosphines and arsines have been prepared and characterized since the initial reports on o-phenylenebisdimethylarsine and 1,2-bisdiphenylphosphinoethane (Table 64 XVIII, III) by Chatt and Mann,1267 and Wymore and Bailar126 respectively. The most common diphosphines, diarsines, distibines and mixed donor ligands are collected in Table 64 and selected nickel(II) complexes are reported in Table 65. 

McAuliffe and co-workers and Dyer and Meek studied nickel(II) complexes with ligands containing methylated arsines Sbtas (XLVII), Bitas (XLVIII) and either thiomethyl or selenomethyl groups Pts (IL) and Ptse (L).1406-1410 The two ligands Pts and Ptse give complexes with different stoichiometry and coordination geometry. 

---