Arsine complexes platinum

Fig. 5. Platinum complexes of olefinic arsines acting as monodentate ligands...

The platinum complex of (W fAo-aUylphenyldimethyl arsine, PtBrg (oA)2, has also been treated with bromine and the products reacted with alcohols (8, 10). Two differences in the reaction sequences are, however, observed ... 

Acyl-platinum complexes are prepared from o-hydroxybenzaldehyde (salicylalde-hyde) and KjPtCl Heating salicylaldehyde, KjPtCl and KjCOj in DMSO at 140°C for 40 min, followed by partial cooling and addition of ligands such as phosphines, arsines or substituted pyridines, gives the yellow chelated acyl complexes... 

E = As, Sb or Bi) react similarly with Grignard reagents, providing routes to cyclic arsines, stibines and bismuthines. Leung s group has reported further applications of asymmetric Diels-Alder cyclisation reactions in phosphine synthesis. A platinum complex chiral auxiliary has been used to promote the asymmetric [4-1-2] Diels-Alder addition of diphenyl(vinyl)-phosphine to 3-diphenylphosphinofuran, giving the eradocycloadduct (70) as the predominant stereoisomer. Related cycloadditions between 3,4-dimethyl-1 -phenylphosphole and ester-functionalised allylic phosphines have provided chemoselective routes to optically-pure P-chiral 1,2- and... 

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... 

J. C. Bailar, Jr., and Hiroshi Itatani, Homogeneous Catalysis in the Reactions of Olefinic Substances. VI. Selective Hydrogenation of Methyl Linoleate and Isomerization of Methyl Oleate by Homogeneous Catalysis with Platinum Complexes Containing Triphenylphosphine, Arsine or Stibine, J. Am. Chem. Soc. 89 1592 (1967). 

Complexes are similarly formed by polydentate phosphine and arsine ligands synthetic routes involve oxidation of the platinum(II) complex, either with the halogen or with nitric acid ... 

Platinum(IV) complexes of phosphine and arsine ligands formed by oxidation with chlorine or bromine are well known. Chloro complexes such as ci5-[PtCl2(PEt3)4]2+ can be generated by electrolysis of the platinum(II) complex c -[PtCl2(PEt3)2].433 Similar platinum(IV) complexes... 

Chelate complexes could only be prepared in the case of platinum(II) as the metal ion, while the group V atom alone acted as a donor toward palladium(II) and mercury(II). The coordinated olefin in the chelate complexes was found to be readily displaced by monodentate ligands such as tertiary arsines, -toluidine and the thiocyanate ion. It was suggested by these workers that chelation would take place more readily if the olefinic phosphine or arsine were subject to greater steric restrictions than was the pentenyl ligand. 

For this reason Long (7, 8) and Erskine 8—11) prepared two series of ligands the ortho, meta and para-styryl dimethyl arsines Long), and the o, m and -allylphenyldimethylarsines Erskine) and studied the bromination of these compounds, their methiodides and their platinum (II) and rhodium(III) complexes. 

It was found that the platinum(II) complexes of these ligands were of two types. All isomers form compounds of the t)rpe PtBr2 (arsine) 2, some of which are illustrated in Fig. 5. In these compounds, coordination to the platinum is effected through the arsenic atom alone. In addition, the ortho isomers of both arsines form 1 1 complexes with platinum(II) bromide in which the ligand is bidentate. Both the arsenic atom and the double bond are coordinated to the platinum as shown in Fig. 6. 

PtBrs (arsine) 2, which are octahedral complexes of platinum(IV) in which the olefinic side chains of the ligands have been fully brominated. An alternative and more realistic formulation of these compounds is PtBr4 (arsine Bre) 2- These same compounds are formed by reaction of an excess (> 3 equivalents) of bromine with the original platinum(II) compounds. 

Treatment of the chelate complexes with a large excess of bromine in hot benzene gives the same complexes PtBr4 (arsine), indicating the resistance of the metal carbon ff-bond to attack by bromine and also excluding ) their alternative formulation as dimeric platinum(II) complexes [PtBrg (arsine Br2)]2-... 

Phosphines and arsines containing more than one olefinic group were neglected as possible multidentate ligands until Hall prepared the tris (orfAo-vinylphenyl) derivatives of phosphorus, arsenic and antimony (tvpp, tvpa and tvps) and their platinum(II) (48) and rhodium(I) (49) complexes. 

These ligands all form 1 1 complexes with platinum(II) halides which are non-conductors, monomeric and, in the solid state, contain one coordinated and two free double bonds. Proton n.m.r. data indicate that all three double bonds are equivalent in solution due to a rapid equilibrium between bonded and non-bonded —CH=CH2 groups. The phosphine and arsine complexes PtBraL (L = tvpp, tvpa) react with two equivalents of bromine giving what are believed to be platinum(II) species containing one coordinated double bond and two —CHBr-CHaBr groups arising from the saturation by bromine of the two free double bonds. 

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