N,O-chelating dicarbonylhydrazido-palladium complexes were synthesized by treatment
of 1,2-bis(trifluoroacetyl)hydrazine with a mixture of a Pd(0) source, [Pd(dba)2] (DBA = dibenzylideneacetone),
and four-electron donors including 1,3-bis(diphenylphosphino)propane (DPPP),
N,N,N0 ,N0-tetramethylethylenediamine (TMEDA), and two equivalents of triphenylphosphine. The
same products from DPPP and TMEDA could be obtained alternatively by using Pd(OAc)2 through
deprotonation of the diacylhydrazine. The five-membered chelate structure was confirmed by NMR
spectra and X-ray crystal structure determination. The X-ray structures indicate that the products
are formally considered as Pd(II) complexes with a hydrazido(2–) ligand. In the case of the
triphenylphosphine-coordinated complex, a fluxional behavior in dichloromethane-d2 was observed
by variable temperature NMR experiments, possibly due to structural changes between the square
planar and pseudo-tetrahedral geometries.
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