Cobalt carbonyl anion derivatives

This alkoxycarbonylation reaction is also catalytic, if the alkylcobalt tetracarbonyl is formed from an epoxide and cobalt carbonyl anion in a hydroxylic solvent (9). A stoichiometric amount of base is not required in this reaction. The initial product, a derivative of the anion of 2-hydroxy-ethylcobalt tetracarbonyl, may undergo three reactions (a) react with more epoxide to give polymer, (b) undergo an internal hydride shift to form aldehyde or ketone, or (c) undergo protonation, carbon monoxide insertion, and alcoholoysis (or hydrolysis) to form ester (or acid). Varying amounts of... 

In a similar manner, Jt-allyl complexes of manganese, iron, and molybdenum carbonyls have been obtained from the corresponding metal carbonyl halides [5], In the case of the reaction of dicarbonyl(r 5-cyclopentadienyl)molybdenum bromide with allyl bromide, the c-allyl derivative is obtained in 75% yield in dichloromethane, but the Jt-allyl complex is the sole product (95%), when the reaction is conducted in a watenbenzene two-phase system. Similar solvent effects are observed in the corresponding reaction of the iron compound. As with the cobalt tetracarbonyl anion, it is... 

Regarding the function of the cobalt component, we find for different iodide charges (at fixed Ru, Co) there is a close parallel between HOAc productivity and the presence of the cobalt carbonyls, and a linear relationship between lOAc and [Co(CO)4] anion content (see Figure 6). This linear correspondence, taken together with the [Co], HOAc selectivity correlation of Figure 3, is indicative of cobalt carbonyl—or a derivative thereof- being responsible for the formation of the desired acetic acid. 

In the case of rhodium, however, it was demonstrated early that in the synthesis of [Rh6C(CO)l5]2 the encapsulated carbon atom originated as chloroform, which had reacted with the rhodium carbonyl anion [Rh7(CO)l6]3- (59). In the cobalt analog, [Co6C(CO)l5]2-, the carbon atom is derived indirectly from carbon tetrachloride [via Co3(CO)9CCl] (60) Both these syntheses are performed under mild conditions, and there are apparently no examples of carbidocarbonyl clusters of cobalt or rhodium prepared directly from the metal carbonyls under pyrolysis conditions. 

Acylcobalt carbonyl derivatives are cleaved by sodium methoxide to esters and sodium salts of the corresponding carbonyl anions. By means of this reaction, acetyl[bis(trimethylolpropane phosphite)]cobalt dicarbonyl has been converted into sodium [bis(trimethylolpropane phosphite)]cobalt dicarbonyl. The latter compound is readily alkylated by methyl iodide to form the methylcobalt derivative and this compound in turn reacts with another mole of the phosphite ester, in the same way that methylcobalt tetracarbonyl does, to form acetyl[tris(trimethylolpropane phosphite)]-cobalt carbonyl ... 

Octahedral cluster iridiiam carbonyl derivatives have also been described (275), but these have been investigated in less detail than their cobalt or rhodium analogs. They are obtained by the alkali-metal reduction of Irit(C0)i2 in a manner somewhat similar to the preparation of octahedral cluster cobalt carbonyl derivatives by the alkali-metal reduction of Coit(C0)i2 Reaction of Irij(C0)i2 with sodium metal in tetrahydrofuTcin first gives the tetrahedral cluster anion Hirij (CX7) i" aind then the dark brown, octahedral cluster anion Ir0(CO)i5 , which can be isolated as its tetraethylammonixam salt (275). ... 

The stoichiometries of anionic metal carbonyls follow from the requirement of inert gas configuration for the metal atom. It is apparent, for example, why the usual carbonyl anions of vanadium, manganese, and cobalt have the formulas [V(CO)6] , [Mn(CO)5] , and [Co(CO)4]-, respectively. In addition, in almost all neutral metal carbonyl derivatives, such as those prepared by reactions involving alkali metal derivatives of metal carbonyls, the metal atom will also have the inert gas configuration. A very few exceptions will arise in these the metal atom will have one electron less than the inert gas... 

In contrast to the several anionic carbonyl derivatives of iron, only one anionic cobalt carbonyl is known which does not contain other ligands. This is the tetrahedral [Co(CO)4] anion, isoelectronic with the neutral Ni(CO)4 and with the [Fe(CO)4] anion. The [Co(CO)4] ion may be obtained by a variety of methods such as the following ... 

A particularly important derivative of the [Co(CO)4] anion is the hydrogen derivative, HCo(CO)4. Although this compound is commonly called cobalt carbonyl hydride , the term hydride is actually a misnomer since the hydrogen atom in HCo(CO)4 is not hydridic but strongly protonic in character HCo(CO)4 is as strong an acid as sulfuric acid (9S). Because of its unusual properties and relative simplicity, HCo(CO)4 has been the subject of several spectroscopic (225, 228, 229) and theoretical 230) investigations. 

Catalysis by cobalt(III) has been the subject of several papers.185-187 The N.N-bis(sahcyldene)ethylnediaminocobalt(III)-catalysed oxidative carbonylation of o-, m-and -substituted primary aromatic amines in MeOH gives ureas, isocyanates, carbamates, and azo derivatives. A Hammett p value of —0.5 for the reaction indicates that electrophilic attack of CO at a nitrogen anion complexed to Co in the TS is... 

Thirteen-vertex complexes of metals other than cobalt have been prepared, as have commo thirteen-vertex anions and metal carbonyl derivatives (18). In general, these complexes exhibit stabilities similar to or less than their twelve-vertex counterparts. 

This potassium salt, K4Ni2(CN)6, may be further reduced by potassium in liquid ammonia to yield a yellow substance, K4Ni(CN)4. This has nickel in the zero-valent state and is thus comparable to the metal carbonyls, Fe(CO)5 and Ni(CO)4 (p. 157), to cobalt nitrosyl carbonyl Co(CO)4NO, and to the metal ammoniates Ca(NH3)6 and Pt(NH3)2. However, K4Ni(CN)4, and the closely related acetylene derivative, K4Ni(C=CH)4, are especially unusual, for in them, the zero-valent metal has been incorporated into an anion, whereas in the carbonyls and metal ammoniates, the zerovalent metals are present as uncharged species. 

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