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Crystal Packing and Magnetism in Phenolic Nitronylnitroxides: 2‑(3′,5′-Dimethoxy-4′-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro‑1H‑imidazole-1-oxyl
journal contribution
posted on 2013-02-06, 00:00 authored by Gonca Seber, Rafael S. Freitas, Nei Fernandes Oliveira, Paul M. Lahti2-(3′,5′-Dimethoxy-4′-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl (SyrNN) forms a hydrogen bonded network
of contacts involving phenolic OH and nitronylnitroxide methyl groups
as donors, and nitronylnitroxide NO groups as acceptors. The SyrNN
intermolecular contact network is quite similar to that of 2-(4′-hydroxyphenyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl (HOPhNN) (Cirujeda et al., J.
Mater. Chem. 1995, 5, 243–252),
which shows ferromagnetic exchange interactions, but SyrNN has an
additional antiparallel stacking contact between nitronylnitroxide
NO groups that qualitatively and computationally is expected to induce
antiferromagnetic (AFM) exchange between SyrNN molecules. Experimentally,
the magnetism of SyrNN shows evidence of multiple exchange interactions
with overall low dimensional AFM exchange behavior. Fits of dc magnetic
susceptibility versus temperature data for SyrNN to AFM 1-D chain
and 2-D square planar models give J/k ∼ (−)1–3 K.