Solid-state molecular rotators of anilinium and adamantylammonium in [Ni(dmit)2]- salts with diverse magnetic properties

Supramolecular rotators of hydrogen-bonding Assemblies between anilinium (Ph-NH3+) or adamantylammonium (AD-NH3+) and dibenzo[18]crown-6 (DB[18]crown-6) or meso-dicyclohexano[18]crown-6 (DCH[18]crown-6) were introduced into [Ni(dMit)(2)] salts (dmit(2-) is 2-thioxo-1,3-dithiole-4,5-dithiolate). The ammonium moieties of Ph-NH3+ and AD-NH3+ cations were interacted through N-H+similar to O hydrogen bonding with the six oxygen atoms of crown ethers, forming 1:1 supramolecular rotator-stator. structures. X-ray crystal-structure analyses revealed a jackknife-shaped conformation of DB[18]crown-6, in which two benzene rings were twisted along the same direction, in (Ph-NH3+)(DB[18]crown-6)[Ni(dmit)(2)](-) (1) and (AD-NH3+)(DB[18]crown-6)[Ni(dmit)(2)](-) (3), whereas the conformational flexibility of two dicyclohexyl rings was observed in (Ph-NH3+)(DCH[18]crown-6)[Ni(dmit)(2)](-) (2) and (AD-NH3+)(DCH[18]crown-6)[Ni(dMit)(2)](-) (4). Sufficient space for the molecular rotation of the adamantyl group was achieved in the crystals of salts 3 and 4, whereas the rotation of the phenyl group in salts 1 and 2 was rather restricted by the nearest neighboring molecules. The rotation of the adamantyl group in salts 3 and 4 was evidenced from the temperature-dependent wide-line H-1 NMR spectra, dielectric properties, and X-ray crystal structure analysis. ab initio calculations showed that the potential energy barriers for the rotations of adamantyl groups in salts 3 (Delta E approximate to 18 kJmol(-1)) and 4 (Delta E approximate to 15 kJmol(-1)) were similar to those of ethane (similar to 12 kJmol(-1)) and butane (17-25 kJmol-1) around the C-C single bond, which were 1 order of magnitude smaller than those of phenyl groups in salts 1 (Delta E approximate to 180 kJmol(-1)) and 2 (Delta E approximate to 340 kJmol(-1)). 1D or 2D [Ni(dmit)(2)](-) anion arrangements were observed in the crystals according to the shape of crown ether derivatives. The 2D weak intermolecular interactions between [Ni(dMit)21- anions in salts 1 and 3 led to Curie-Weiss behavior with weak antiferromagnetic interaction, whereas 1 D interactions through lateral sulfur-sulfur atomic contacts between [Ni(dMit)(2)](-) anions were observed in salts 2 and 4, whose magnetic behaviors were dictated by ferromagnetic (salt 2) and singlet-triplet (salt 4) intermolecular magnetic interactions, respectively.