Organocobalt i complexes with carbene ligands

This complex has been obtained by adding an excess of MeLi onto the corresponding dibromide cobalt derivative with the same tridentate ligand, or more cleanly onto the monobromide cobalt A -heterocyclic pincer dicarbene derivative. The complex displayed a square-planar structure. This seems to be the first example of a Co(i)-alkyl complex stabilized by a CNC pincer ligand and lacking any tr-acccptor coligands. 

These / -elimination-resistant alkyl complexes 66 present an interesting reactivity toward insertion reaction such as with CO, leading to a 17-electron acyl(carbonyl) complex 68 (see Equation (6)). Other small unsaturated organic molecules have been used by Akita s group, but only phenylacetylene has led to C-C bond formation, affording, after hydrolysis of the solution, a mixture of -phenyl-1-butene with 68% yield. 

The alkynyl TpCo derivatives have been prepared via an original route of dehydrative condensation of the hydroxo complex [Tp Co(/r-OH)]2 with alkynes (Equation (7)). The complexes formed 70 have a high spin configuration (S = 3/2). 

Gibson etal have obtained a methyl[bis(imino)carbazolide]cobalt(n) complex 73 from the chloride derivative 72 (Equation (8)). The chloride complex in the presence of MAO was expected to produce oligomerization or polymerization of ethylene but no reaction has been observed, which is in marked contrast to the high polymerization activity of related bis(imino)pyridine complexes of 

The kinetics of formation of complexes with Co-C bonds in the reaction between [Co(NH3)sH20] or [Go(NH3)6] with different aliphatic radicals (R = CH3, CH2C02, CH2OH) was studied in aqueous solutions using the pulse radiolysis technique. The formation of ((NH3)5Co -R) + obeys pseudo-first-order rate laws.  

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