Cobalt dimer

Carbonvlation of Benzyl Halides. Several organometallic reactions involving anionic species in an aqueous-organic two-phase reaction system have been effectively promoted by phase transfer catalysts(34). These include reactions of cobalt and iron complexes. A favorite model reaction is the carbonylation of benzyl halides using the cobalt tetracarbonyl anion catalyst. Numerous examples have appeared in the literature(35) on the preparation of phenylacetic acid using aqueous sodium hydroxide as the base and trialkylammonium salts (Equation 1). These reactions occur at low pressures of carbon monoxide and mild reaction temperatures. Early work on the carbonylation of alkyl halides required the use of sodium amalgam to generate the cobalt tetracarbonyl anion from the cobalt dimer(36). 

Fig. 15. The solid state structure of the bis(2,4-dimethylpentadienyl)cobalt dimer, which lies on a crystallographic center of inversion (Ref. 236)...

In methanol solutions, the cobalt dimer also undergoes disproportionation according to... 

Both these reactions produce high yields of the substituted complexes with one ligand in the axial position on each metal almost always. The manganese dimer requires high temperature (120°C), but the cobalt dimer reacts at room temperature, sometimes with the salt [Co(CO)3L2][Co(CO)4] as an intermediate. Warming a solution of the salt leads to the bissubstituted dimer. ... 

The cobalt dimers are recrystallized from pentane at — 78°C. The product is also obtained if MesGeCl is replaced by MeaSiCl or CH3C(0)Cr. A hydridorhodiumphos-phite dimer is prepared by reaction of (/j -CsHsjRhiLS-CgHij) with phosphite under an H2 atmosphere ... 

Numbers in parentheses indicate yield for the respective reactions. Diolefin complexes of cobalt dimers are prepared from the direct reaction of Co2(CO)s with the diolefin ... 

Metal carbonyl dimers are prepared with biscyclopentadienyl linked ligands. The following sequence of reactions is utilized to prepare cobalt dimers E... 

Danset D, Manaron L (2005) Reactivity of cobalt dimer and molecular oxygen in rare gas matrices IR spectrum, photophysics and structure of C02O2. Phys Chem Chem Phys 7 583-591... 

The regiospecific C-alkylation of primary benzylamines cf. Vol. 4, p. 174) has now been simplified by the use of a solid-liquid phase-transfer system. Vicinal diamines are not easily prepared directly from olefins, and although two new methods were recently reported (cf. Vol. 3, p. 170 and Vol. 4, p. 175) these have not been applicable to the preparation of primary diamines. A new method for this transformation involves the use of the cyclopentadienylnitrosyl-cobalt dimer (7), and is considered to be of general applicability. Some stereoselectivity was observed. 

In order to complete the reactivity of isocyanide in this section, the reactivity of a well-known Co(0) isocyanide cobalt dimer is described. Yamamoto s group has also reported the reactivity of the Co(0) complex, Co2(CNXyl)8,... 

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