A practical procedure for the synthesis
of N,N,N′,N′-tetramethylethylene
diamine nickel
dimethyl, [(tmeda)Ni(CH3)2] (5),
based on commercially available methyllithium and [(tmeda)Ni(acac)2] (1)
(acac = acetylacetonate), [(tmeda)Ni(OAc)2] (2) (OAc = acetate), [(tmeda)NiSO4] (3), or
[(tmeda)NiF2] (4) has been developed. With 2 as the starting material, reproducible isolation of >14
g (ca. 68 mmol, 85%) of 5 in one-batch reactions is feasible.
This synthetic route also enables the formation and isolation of 13C-labeled [(tmeda)Ni(13CH3)2] (5-
13
CH
3
) starting from 13CH3I by intermediate
isolation of [(tmeda)2–3(Li13CH3)4]
x
(10). The
amount of iodide impurities in 10 to push back iodide-catalyzed
decomposition of 5-
13
CH
3
to ethane and nickel black by a Kumada-type
coupling is essential for successful isolation of 5-
13
CH
3
. [(tmeda)Ni(OAc)2] (2) is a superior nickel precursor to 5 in comparison to [(tmeda)Ni(acac)2] (1), as (a) removal of lithium acetate (9) from the crude
reaction mixture is much easier than removal of lithium acetylacetonate
and (b) κ2-N,O-salicylaldiminato
nickel methyl complexes (12) or a κ2
-P,O-phosphinesulfonato nickel methyl complex (14) can be easily prepared in a one-pot procedure starting
from 2, methyllithium, and salicylaldimines (11) or phosphoniumsulfonate (13), respectively. The X-ray
diffraction analyses of 2, 5, and 12b-PPh
3
are reported.