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Supramolecular Rotators of (Aniliniums)([18]crown-6) in Electrically Conducting [Ni(dmit) 2 ] Crystals

2012; American Chemical Society; Volume: 51; Issue: 23 Linguagem: Inglês

10.1021/ic302093b

1520-510X

Norihisa Hoshino, Yuuya Yoshii, Masaki Aonuma, Kazuya Kubo, Takayoshi Nakamura, Tomoyuki Akutagawa,

Solid-state spectroscopy and crystallography

Supramolecular assemblies of anilinium (Ani+) and fluoroanilinium derivatives (FAni+) with [18]crown-6 were introduced into electrically conducting [Ni(dmit)2] crystals (dmit2– is 2-thioxo-1,3-dithiole-4,5-dithiolate). The crystal structures, electrical conductivities, and magnetic susceptibilities of four new crystals of (Ani+)([18]crown-6)[Ni(dmit)2]3 (1), (o-FAni+)([18]crown-6)[Ni(dmit)2]3 (2), (m-FAni+)([18]crown-6)[Ni(dmit)2]3 (3), and (p-FAni+)([18]crown-6)[Ni(dmit)2]3 (4) were examined from the viewpoint of dynamic supramolecular rotator structures within the crystals. The crystal structures, electrical conduction, and magnetic properties were classified into group-I (crystals 1 and 4) and group-II (crystals 2 and 3). The hydrogen-bonding interaction between -NH3+ and the oxygen atoms of [18]crown-6 formed the stand-up configuration of rotator-stator structures of (Ani+)([18]crown-6) and (FAni+)([18]crown-6) supramolecules. The potential energy barriers for the 2-fold flip-flop motion of phenyl- and p-fluorophenyl-rings in crystals 1 and 4 had a relatively small magnitude of ∼150 kJmol–1, suggesting that rotations of Ani+ and p-FAni+ cations around the C-NH3+ axis occurred in the crystals. In contrast, a large magnitude of the potential energy barriers for the rotations of o-FAni+ and m-FAni+ cations in crystals 2 and 3 (>600 kJmol–1) resulted in static supramolecular cationic structures. The cation:anion ratio of 1:3 in these crystals yielded a trimer π-stack of [Ni(dmit)2] with a semiconductor-like temperature dependence. The magnetic susceptibilities of the static crystals 2 and 3 were reproduced by the one-dimensional antiferromagnetic linear Heisenberg chain through the one-dimensional linear trimer arrangement. The magnetic susceptibilities of dynamic crystals 1 and 4 enhanced electron delocalization through the intratrimer and intertrimer interactions within the trimer stack, where the molecular rotations of Ani+ and p-FAni+ cations played an important role.