Homochiral 1D helical chain based on an achiral Cu(II) complex.

Self-assembly of an achiral [Cu(L)] complex produced a homochiral helical chain [Cu(L)](3)·2H(2)O (1) (L = 2-dimethylaminoethyl(oxamato)). Interestingly, complex 1 obtained in our laboratory exhibits only a left-handed helical chain without any chiral source. Single-crystal X-ray analysis revealed the absolute structure and homochirality of its helical chain structure in the space group of P3(2). Solid-state circular dichroism (CD) spectra confirmed the high enantio excess of the crystals obtained in different synthesis batches. Magnetic susceptibility measurements reveal a relatively strong intrachain antiferromagnetic interaction between Cu(II) centers via an oxamato bridge (J = -74.4 cm(-1)).

Ionic liquids of cationic sandwich complexes.

Simple cationic sandwich complexes that contained alkyl- or halogen substituents provided ionic liquids (ILs) with the bis(perfluoroalkanesulfonyl)imide anion. Ferrocenium- and cobaltocenium ILs [M(C(5)H(4)R(1))(C(5)H(4)R(2))][Tf(2)N] (M=Fe, Co) and arene-ferrocenium ILs [Fe(C(5)H(4)R(1))(C(6)H(5)R(2))][Tf(2)N] were prepared and their physical properties were investigated. A detailed comparison of their thermal properties revealed the effects of molecular symmetry and substituents on their melting points. Their viscosity increased on increasing the length of the substituent on the cation and the perfluoroalkyl chain length on the anion. Upon cooling, ILs with low viscosities exhibited crystallization, whereas those with higher viscosities tended to exhibit glass transitions. Most of these salts showed phase transitions in the solid state. A magnetic-switching phenomenon was observed for the paramagnetic ferrocenium IL, which was associated with a liquid/solid transformation, based on the magnetic anisotropy of the ferrocenium cation. (57)Fe Mössbauer spectroscopy was applied to [Fe(C(5)H(4)nBu)(2)][Tf(2)N] to investigate the vibrational behavior of the iron atom in the crystal and glassy states of the ferrocenium IL.

Unprecedented three-step spin-crossover transition in new 2-dimensional coordination polymer {Fe(II)(4-methylpyridine)(2)[Au(I)(CN)(2)](2)}.

A new spin crossover (SCO) coordination polymer, {[Fe(II)(4-methylpyridine)(2)][Au(I)(CN)(2)](2)}(n) () has been synthesized. The complex () has been observed to have a thermal induced three-step SCO transition, which is unprecedented behavior as compared with existing SCO complexes. In the complex, about 18%, 41% and 41% high spin states are changed to low spin states in the first-step, second-step and third-step, respectively.

A new spin crossover heterometallic Fe(II)Ag(I) coordination polymer with the [Ag(2)(CN)(3)](-) unit: crystallographic and magnetic study.

The novel bimetallic Fe(II)Ag(I) thermal-induced spin crossover coordination polymer {Fe(II)(3,5-dimethylpyridine)(2)[Ag(I)(2)(CN)(3)][Ag(I)(CN)(2)]}(n) was synthesized by one-pot reactions between 3,5-dimethylpyridine and K[Ag(I)(CN)(2)] in the presence of Fe(II) salt (FeSO(4).(NH(4))(2)SO(4).6H(2)O). Magnetic studies demonstrate the occurrence of a spin transition. The crystal structure has been studied at 293 K and 80 K. The compound is made up of unprecedented three-dimensional networks topology of Fe(II) ions bridged by binuclear [Ag(I)(2)(CN)(3)](-) and mononuclear [Ag(I)(CN)(2)](-) units; [Ag(I)(2)(CN)(3)](-) anion is very rare. In this complex, the presence of the Ag(I) ions plays a significant role in increasing the dimensionality and cooperatively due to the triangular argentophilic interactions.