Ethanol Imine Ligands and their Nickel Complexes

Ethanol Imine Ligands and their Nickel Complexes 

The first route uses benzoin derivatives as intermediates. These become available from 1-trimethylsilyloxyphosphonates, which are prepared from aldehydes in an one-pot procedure. The phosphonates are then transformed into benzoins 

In consecutive screening experiments for polymerization activity [vide infra) it was found that the triphenylphosphane donor was not easily removed. Therefore, methyl nickel precatalysts were synthesized starting from (tmeda)NiMe2 [31] as the nickel reagent, resulting in the formation of several compounds of which (N,O)2Ni and an oxygen-bridged dimer (N,O)Ni-Me 2 were identified by NMR and FAB-mass spectroscopy. However, this mixture of Ni hydroxy imine com- 

In some cases, a second product was also formed in the synthesis. This was identified as a CH activated or ortho-metalated complex (N,0)Ni-(o-Ph)PPh2= CH2, where an ortho C-H bond of a phosphorane phenyl group was deprotonated by the Ni-Me moiety with concomitant formation of methane. Fig. 3.10 shows the molecular structure of complex 132 obtained from ligand 114. The central square planar Ni atom is part of two five-membered metallacycles. 

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