Palladium(II) acetate reacts with 1 equiv of 1,4,7-trithiacyclononane
(9S3) at room temperature to produce the neutral complex [Pd(9S3)(OAc)2] (1; OAc– = CH3COO–) as an analytically pure yellow solid, which
has been characterized using 1H and 13C NMR
spectroscopy and single-crystal X-ray diffraction. The crystal structure
of 1 shows the first example of an exodentate third sulfur of the 9S3 ligand in a Pd(II) complex. Complex 1 reacts with nitromethane at room temperature in methanol
to produce [Pd(9S3)(CH2NO2)2] (2) and acetic acid, as confirmed by 1H NMR and 13C NMR spectroscopy. Moreover, complex 2 has
been characterized by single-crystal X-ray diffraction. Its crystal
structure is the first example of any transition-metal complex containing two nitromethanate (anionic nitromethane) ligands. The complex
shows the more typical elongated-square-pyramidal structure and [S2C2 + S1] coordination with one long
Pd–S axial interaction at 2.823(2) Å and two C-bound nitromethanate
ligands. Interestingly, each nitromethanate ligand is in a different
coordination environment and varies in their trans-directing abilities.
Reactivity studies suggest that the complexation behavior of the 9S3
ligand and the Pd(II) center as well as the σ-donor ability
of the leaving group play key roles in the C–H activation of
the nitromethane. Two related metal complexes, [Pd(dppe)(OAc)2] (dppe = 1,2-bis(diphenylphosphino)ethane) and [Pd(9S3)(CF3COO)2], were synthesized, but neither of these
react in a similar fashion to form a nitromethanate complex. Also,
the reaction of 1 with nitrobenzene and nitrocyclopentane
was studied, but these nitro-organics do not undergo C–H bond
activation like nitromethane.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.