Facile Preparation of Organometallic Nanorods from Various Ethynyl-Substituted Molecules.

A facile method to prepare one-dimensional (1D) organometallic nanomaterials from various ethynyl-substituted molecules is reported. The reactions of 3-chloro-1-ethynylbenzene, -Bu-phenylacetylene and 4-ethynylbiphenyl with Cu ions in acetonitrile yield nanorod-shaped copper acetylides (Cu-C≡C-R) crystals. In the case of linear alkynes, namely, propyne, 1-pentyne and 1-hexyne, it was found that using an aqueous ammonia/ethanol mixed solvent instead of acetonitrile is a better approach to obtain 1D nanostructures.

A series of weak ferromagnets based on a chromium-acetylide-TTF type complex: correlation of the structures and magnetic properties and origin of the weak ferromagnetism.

The crystal structures and magnetic properties of a series of new weak ferromagnets containing a chromium-acetylide-tetrathiafulvalene (TTF) type complex, [CrCyclam(C≡C-5-methyl-4'5'-ethylenedithio-TTF)2](2+) ([1](2+)), were investigated. The six new isostructural weak ferromagnets [1][BF4]2(PhF)2(MeCN), [1][ClO4]2(PhF)2(MeCN), [1][ReO4]2(PhCl)2(MeCN), [1][ClO4]2(PhBr)3, [1][ReO4]2(PhBr)3, and [1][ClO4]2(PhI)3 contain ferrimagnetic chain structures of [1](2+)∞ with different interchain distances that are dependent on the sizes of the anions and solvent molecules. Magnetic measurements of the salts revealed that the weak ferromagnetic transition temperature gradually increases from 14.

Weak ferromagnetism and strong spin-spin interaction mediated by the mixed-valence ethynyltetrathiafulvalene-type ligand.

A new chromium complex with ethynyltetrathiafulvalene (TTF)-type ligands, [CrCyclam(C≡C-5-methyl-4'5'-ethylenedithio-TTF)(2)]OTf ([1]OTf), was synthesized. The cyclic voltammetry of the complex shows two reversible oxidation waves owing to the first and second oxidation of the TTF unit. The electrochemical oxidation of [1]OTf in a Bu(4)NClO(4) or Bu(4)NBF(4) solution of a 1:1 acetonitrile-chlorobenzene mixture gave isostructural crystals of [1][ClO(4)](2)(PhCl)(2)(MeCN) and [1][BF(4)](2)(PhCl)(2)(MeCN), where two mixed-valence TTF units of adjacent complexes form a dimer radical cation.

Chromium acetylide complex based ferrimagnet and weak ferromagnet.

The crystal structures and magnetic properties of new molecule-based magnets, [CrCyclam(C[triple bond]C-3-thiophene)(2)][Ni(mdt)(2)] (1) and [CrCyclam(C[triple bond]C-Ph)(2)][Ni(mdt)(2)](H(2)O) (2) (Cyclam = 1,4,8,11-tetraazacyclotetradecane, mdt = 1,3-dithiole-4,5-dithiolate), are reported. The crystal structures of both compounds are characterized by ferrimagnetic chains of alternately stacked [CrCyclam(C[triple bond]C-R)](+) cations and [Ni(mdt)(2)](-) anions with intrachain exchange interactions of 2J = -6.1 K in 1 and -5.

d-Electron-induced negative magnetoresistance of a pi-d interaction system based on a brominated-TTF donor.

A new pi-d interaction system (EDT-TTFBr2)2FeBr4 (EDT-TTFBr2 = 4,5-dibromo-4',5'-ethylenedithiotetrathiafulvalene) and its nonmagnetic anion analogue (EDT-TTFBr2)2GaBr4 based on a brominated TTF-type organic donor are investigated. The salts featured by quasi-1D pi-electronic systems are metallic with metal-insulator transitions taking place at about 20 and 70 K for the FeBr4- and GaBr4- salts, respectively, where the low-temperature insulating state is associated with charge ordering or a Mott insulator followed by an antiferromagnetic transition at lower temperatures. The FeBr4- salt is featured with an antiferromagnetic transition of the anion d spins at a Neel temperature (TN) = 11 K, which is significantly high despite its long anion-anion Br-Br contact, suggesting the importance of the pi-d interaction in the magnetism.