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Abstract
The use of first row transition metals in catalysis as a substitute for scarce and expensive second
and third row transition metals is still a challenge One strategy to promote the use of first row
transition metals is the use of bimetallic complexes as the cooperativity between the metal
centers might enable reaction pathways that are not accessible with mononuclear catalysts.
Therefore, the aim of this study was to prepare a catalytically relevant bimetallic Nickel(II)complex with bridging NCP ligands and a chloro ligand at each metal center (Scheme 1).
Reaction of a nickel(II) monomer with sodium azide did not yield the desired dimer as
replacement of chloro ligands by azido ligands occurred, yielding a dimer with square planar
configuration at each metal center. Abstraction of the chloro ligand from the monomer followed
by reaction with sodium azide was also unsuccessful. However, reaction of the monomer with
methyllithium led to cleavage of the silyl-carbon bond, indicating that the projected dimer
formation can be achieved. However, hydrolysis of the carbanion prevented formation of the
desired complex. The exact nature of this product is not known and the compound needs to be
characterized more thoroughly. In addition, dimer formation via reaction with methyllithium
has to be examined in extensively dried conditions in order to see whether the formed carbanion
can lead to formation of the desired dimer.
Ph
Ph
P
N
SiMePh 2
Cl
Ni
N
Ni
P
Cl
Ph
SiMePh 2
Ph
Scheme 1 The projected nickel(II)-dimer