Carbodiimide complexes

The imido complexes Cp Ir=NR have many insertion reactions108 for example, Cp Ir=NBu reacts with Bu NC to give the rf-N,C-carbodiimide complex Cp Ir( 72-Bu NCNBu )(CNBu ). However, other isocyanides may react differently.109... 

The nickel carbodiimide complex 181 reacts with carbon monoxide to give carbodiimide 182 in 50 % yield. ... 

The 1,3-dipolar addition of phenylazide to metal coordinated ligands affords carbodi-imide ligands. An example is the reaction of the bis-azidopalladium complex 38 with two equivalents of 2,6-dimethylphenyl isocyanide to give the bis-carbodiimide complex 39. ... 

Reaction of CpCo(CNCH2Ph)(PMc3) with phenyl azide affords the carbodiimide complex CpCo(CNPh-PhCH2N=C=NPh)(PMe3 ). ... 

The photolysis of the rhodium carbodiimide complex 60 in liquid propylene affords the allyl derivative 61. ... 

Fig. 2.100. Mechanism proposed for the reaction of the [Rh(Tp )(CNneopentyl)] fragment, obtained photochemically from the carbodiimide complex, with chloro-substituted alkanes.

Fig. 10. Molecular structure of the carbodiimide complex 702 (hydrogen atoms omitted).

Photolysis of the carbodiimide complex 395 in hydrocarbon solvents similarly effects C H activation, via initial dissociation of the carbodiimide ligand to afford Tp Rh(CNCH2 Bu) as the active species. The reaction proceeds in a variety of neat aliphatic hydrocarbons, with apparently exclusive selectivity for the primary C H of terminal methyl groups. This includes the case of chloroalkanes, for which no oxidative addition of the C Cl bond is observed. Competition is, however, noted for aromatic substrates bearing methyl substituents, " with both benzylic and aromatic activation proceeding under kinetic control, though the aromatic activation products are thermodynamically favoured. Thus, toluene affords a kinetic mixture of aryl and benzyl complexes, which thermally redistributes to a 2 1 mixture of meta and para isomers of the aryl complex, while mesitylene yields a 3 1 mixture of the mesityl and benzyl complexes. 

Terminal alkynes also add to [Tp Rh(CNR)]. Irradiation of the carbodiimide complex 1 in neat 1-alkyne leads to the activation of the sp C-H bond. In cases where other activatable C-H bonds were presented, competitive C-H activation at these positions was observed. For example, t-butylacetylene and trifluoromethyl acetylene give exclusively alkynyl hydride products, whereas 1-octyne and trimethylsilylacetylene also give products resulting from methyl group activation. In both of the latter cases, the sp C-H activation products are unstable and convert to the terminal alkynyl products at room temperature after a few days (Scheme 1). Similarly, the activation of arylalkynes leads to mixtures of sp and sp C-H activation products. The unsaturated fragment [Tp Rh(CNR)] was prepared either... 

Treatment of CpRh(CNMe)(PMe3) with ArNs afforded exclusively the metallacycle carbodiimide complexes CpP77(re -C, -MeN=C=NAr)(PMe3) in good yields (Scheme 37). ... 

---