Platinum complexes cobalt

Molecules having only a sulfoxide function and no other acidic or basic site have been resolved through the intermediacy of metal complex formation. In 1934 Backer and Keuning resolved the cobalt complex of sulfoxide 5 using d-camphorsulfonic acid. More recently Cope and Caress applied the same technique to the resolution of ethyl p-tolyl sulfoxide (6). Sulfoxide 6 and optically active 1-phenylethylamine were used to form diastereomeric complexes i.e., (-1-)- and ( —)-trans-dichloro(ethyl p-tolyl sulfoxide) (1-phenylethylamine) platinum(II). Both enantiomers of 6 were obtained in optically pure form. Diastereomeric platinum complexes formed from racemic methyl phenyl (and three para-substituted phenyl) sulfoxides and d-N, N-dimethyl phenylglycine have been separated chromatographically on an analytical column L A nonaromatic example, cyclohexyl methyl sulfoxide, did not resolve. 

Until recently, the hydroformylation using palladium had been scarcely explored as the activity of palladium stayed behind that of more active platinum complexes. The initiating reagents are often very similar to those of platinum, i.e., divalent palladium salts, which under the reaction conditions presumably form monohydrido complexes of palladium(II). A common precursor is (39). The mechanism for palladium catalysts is, therefore, thought to be the same as that for platinum. New cationic complexes of palladium that are highly active as hydroformylation catalysts were discovered by Drent and co-workers at Shell and commercial applications may be expected, involving replacement of cobalt catalysts. 

CsHuN, Ethanamine, A-ethyl-A-methyl-tungsten complex, 26 40, 42 C6HF5, Benzene, pentafluoro-gold complexes, 26 86-90 C H4I2, Benzene, 1,2-diido-iridium complex, 26 125 CJT, Phenyl platinum complex, 26 136 C,H,N, Pyridine osmium complex, 26 291 OHtS, Benzenethiol osmium complex, 26 304 QH7P, Phosphine, phenyl-cobalt-iron complex, 26 353 QH 1-Butyne, 3,3-dimethyl-mercury-molybdenum-ruthenium complex, 26 329-335 C6H 4P, Phosphine, triethyl-platinum complex, 26 126 platinum complexes, 26 135-140 CsHisPO, Triethyl phosphite iron complex, 26 61... 

C7H4N, Benzonitrile platinum complex, 26 345 ruthenium (II) complexes, 26 70-72 CiH , Benzene, methyl-cobalt complex, 26 309 manganese complex, 26 172... 

The metal hydride mechanism was first described for the cobalt-carbonyl-catalyzed ester formation by analogy with hydroformylation.152 It was later adapted to carboxylation processes catalyzed by palladium136 153 154 and platinum complexes.137 As in the hydroformylation mechanism, the olefin inserts itself into the... 

The pentaphenylborole dianion was incorporated as a ligand in transition metal complexes with platinum and cobalt as well as with iron, nickel and manganese. An interesting formation of such a complex from 1-phenyl-4,5-dihydroborepin (53) was performed in boiling mesity-lene in the presence of iron pentacarbonyl. Six-membered borinate complexes were also found in the reaction mixture (77AG43). 

In terms of the development of an understanding of the reactivity patterns of inorganic complexes, the two metals which have been pivotal are platinum and cobalt. This importance is to a large part a consequence of each metal having available one or more oxidation states which are kinetically inert. Platinum is a particularly useful element of this pair because it has two kinetically inert sets of complexes (divalent and tetravalent) in addition to the complexes of platinum(O), which is a kinetically labile center. The complexes of divalent and tetravalent platinum show significant differences. Divalent platinum forms four-coordinate planar complexes which have a coordinately unsaturated 16-electron d8 platinum center, whereas tetravalent platinum is an 18-electron d6 center which is coordinately saturated in its usual hexacoordination. In terms of mechanistic interpretation one must therefore consider both associative and dissociative substitution pathways, in addition to mechanisms involving electron transfer or inner-sphere atom transfer redox processes. A number of books and articles have been written about replacement reactions in platinum complexes, and a number of these are summarized in Table 13. 

Trofimenko also envisioned polypyrazolyl compounds of Be, Al, Ga, In, C, Si and P and prepared some alkane ligands and their complexes.1,2 A few other applications of polypyrazolylalkane ligands have been mentioned in passing in the sections dealing with cobalt and platinum complexes. The reactions of dipyrazolyl ketone to produce [Co(OC(pz)2)Cl2] and [Co(Me2C(pz)2)Cl2], the latter from acetone, are very unusual55 but do not seem to have been exploited further (Scheme 2). 

According to T. Curtius, feme chloride is reduced by hydrazine to ferrous chloride a reaction investigated by E. Miiller and G. Wegdin, and F. Schrader. E. J. Cuy found that in the reaction between hydrazine and a ferric salt in acid soln., one mol of hydrazine requires between one and two eq. of ferric salt for oxidation. The limiting reaction may be expressed as follows N2H 5-)-Fe" =NH 4+JN2+H +Fe". A. W. Browne and F. F. Shetterly showed that ferric oxide and hydrazine in aq. soln, yield ammonia, but no hydrazoic acid, while nickel sesquioxide and cobalt sesquioxide yield ammonia and traces of hydrazoic acid. H. Franzen and 0. von Mayer made complex cobalt salts—e.g. CoC12(N2H4)2, etc.—with hydrazine in place of ammonia. T. Curtius found that platinum is precipitated when a soln. of hydrazine is added to a neutral soln. of platinum... 

Hetero-Diels—Alder reactions, via cobalt(III) complexes, 7,44 Heterodienes, with iron, 6, 145 if- Heterodienes, with tantalum, 5, 176 Heterodinuclear iridium complexes, synthesis, 7, 371 Heterodinuclear iridium—platinum complexes, synthesis and characterization, 7, 380... 

In several other cases, compounds have been synthesized that contain potentially reactive groups attached to silicon, although their functionality has not yet been exploited. These include the methyl-chlorosilyl cobalt derivatives Cl Me3-nSiCo(CO)4 (re = 1,2) (215) and platinum complexes such as fra/is-lEtaPIsPtCXISiHjPISiHals (168) (cf. Table VI, entries 8-10). 

Finally it should be noted that although one might not find a compound listed uhder an incorrect name, there is no guarantee that it will be listed under its correct name either. In consulting a journal index for information about a compound, one may often save time by selecting what appears to be the most important element in the compound and looking under the section devoted to that element. Thus each of the octahedral cobalt complexes pictured above would be likely to be listed under Cobalt Compounds, whereas the two platinum complexes might very well be listed under Platinum Compounds. ... 

Two sorts of metal—cyano complexes have been studied. The first contains an atom of zinc, cadmium, mercury or copper as the central atom, and the nitrogen quadrupole coupling is only a little higher than it is in nitriles (4.0—4.2 MHz against 3.8—4.0 MHz). In the second sort, the central atom is either platinum or cobalt and the observed couplings are markedly lower (3.47—3.68 MHz). 

The preparations described here are developed from published work by Malatesta et al.5 and from more recent studies in the contributors own laboratory.2 The cobalt and nickel complexes are prepared by reduction of the corresponding metal nitrates with sodium tetrahydroborate in the presence of excess ligand, whereas the syntheses of the rhodium and platinum complexes involve simple ligand exchange processes. The preparative routes are suitable for use with triphenyl- or p-substituted triphenyl phosphites reactions involving o- or m-substituted triphenyl phosphites give much reduced yields of products which are difficult to crystallize and are very air-sensitive. These features probably reflect the unfavorable stereochemistry of the o- and m-substituted ligands. 

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