Phosphine-metal complexes cobalt

Phosphines. Polymeric phosphines exhibit strong metal-binding properties. Nonpolymeric phosphines, in particular triphenylphosphine, are employed as ligands for cobalt and rhodium in hydroformylation catalysts used in plasticizer manufacture. Extensive efforts have been made to attach phosphine-metal complexes to polymers in order to facilitate catalyst recovery and enhance selectivity... 

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. 

Many P(CH3)3 complexes of the first-row transition metals may be conveniently prepared by direct reaction with the appropriate anhydrous chromium (II), (III),3 cobalt(II),4 iron(II)s or hydrated iron(II),s nickel(II)4a>6,7 salt. The compound [(CH3)3P] 2FeCl2 is the starting material for a variety of phosphine iron complexes.4,8,9... 

Many of the complexes discussed in the previous sections are catalysts for alkyne oligomerization. In fact, alkyne dimerization and trimerization (see Cyclodimerization -tri-merization Reactions) at a cobalt center is recognized as one of the most synthetically useful catalytic reactions mediated by a homogeneous transition metal complex. The cobalt complexes most useful and extensively studied are CpCoL2, where L is CO, alkene, diene, or phosphine. The complex types... 

This reaction is of interest as an alternative route to the formation of ethylene, since the subsequent dehydration step is well-established. Cobalt complexes are usually used for this reaction with various kinds of promoters such as iodides, phosphines, and other transition metal complexes [1]. 

The use of Co2(CO)g as a hydrogenation catalyst in the absence of CO generally results in decomposition to metal. Phosphine derivatives of cobalt carbonyl complexes, which are more robust hydrogenation catalysts, will be discussed next. 

Numerous other metal complexes were studied by DTA/DSC and other TA techniques including Ni(II), Cu(II) and Co(II), and Co(II) diethyldithio-carbamate complexes (72) bis(2,4-pentanedionato)beryllium (II) and tris-(2,4-pentanedionato)aluminum (III) complexes (101) dihalogendi(tertiary-phosphine) cobalt (II) complexes (102) bis(trispyrrolidinophosphine oxide)-tetranitratouranium(IV) (103) Co(II), Cu(II), and Cd(II) xanthine complexes (104) and alkali and alkaline earth monomethyl violurates (105,108). 

A number of transition metals have been shown to react with trifluoro-phosphine [280]. Chromium, cobalt, nickel, palladium and iron all produced stable complexes. Manganese and copper also reacted at —196°C, but the products were unstable, and decomposed on warming. Nickel vapour has also been reacted with difluorochlorophosphine, yielding Ni(PF2Cl)2. Complexes produced by reaction with phosphine itself were unstable, decomposing on warming, although when a mixture of phosphine and trifluorophosphine was co-condensed with nickel vapour some mixed complexes were isolated. 

Bis(2,4,4-trimethylpentyl)phosphinic add (CYAN EX 272) is extremely selective toward extracting cobalt from aqueous cobalt/nickel solutions [56, 57], and consequently, the corresponding bis(2,4,4-trimethylpentyl)phosphinate salt prepared form entry 6 [58] may have some unique selective metal complexing properties. 

Of the three modes of coordination between a bidentate phosphine ligand and a metal complex (Fig. 8), the chelating mode (B) is most common. The active cobalt-catalyst generated by the reduction of Co " or Co " with EtjAlCl is probably a five-coordinated cobalt complex. Two olefins in NBD and the acetylene occupy three of the five coordi-... 

Cobalt, nickel, iron, ruthenium, and rhodium carbonyls as well as palladium complexes are catalysts for hydrocarboxylation reactions and therefore reactions of olefins and acetylenes with CO and water, and also other carbonylation reactions. Analogously to hydroformylation reactions, better catalytic properties are shown by metal hydrido carbonyls having strong acidic properties. As in hydroformylation reactions, phosphine-carbonyl complexes of these metals are particularly active. Solvents for such reactions are alcohols, ketones, esters, pyridine, and acidic aqueous solutions. Stoichiometric carbonylation reaction by means of [Ni(CO)4] proceeds at atmospheric pressure at 308-353 K. In the presence of catalytic amounts of nickel carbonyl, this reaction is carried out at 390-490 K and 3 MPa. In the case of carbonylation which utilizes catalytic amounts of cobalt carbonyl, higher temperatures (up to 530 K) and higher pressures (3-90 MPa) are applied. Alkoxylcarbonylation reactions generally proceed under more drastic conditions than corresponding hydrocarboxylation reactions. 

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