Syntheses and crystal structures of the ethanol, acetonitrile and diethyl ether Werner clathrates bis(isothiocyanato-κN)tetrakis(3-methylpyridine-κN)nickel(II)

Abstract

The reaction of nickel(II)thiocyanate with 3-methylpyridine (3-picoline; C6H7N) in different solvents leads to the formation of crystals of bis(isothiocyanato-κN)tetrakis(3-methylpyridine-κN)nickel(II) as the ethanol disolvate, [Ni(NCS)2(C6H7N)4]·2C2H5OH (1), the acetonitrile disolvate, [Ni(NCS)2(C6H7N)4]·2CH3CN (2), and the diethyl ether monosolvate, [Ni(NCS)2(C6H7N)4]·C4H10O (3). The crystal structures of these compounds consist of NiII cations coordinated by two N-bonded thiocyanate anions and four 3-methylpyridine ligands to generate NiN6 octahedra with the thiocyanate groups in a trans orientation. In compounds 1 and 2 these complexes are located on centers of inversion, whereas in compound 3, they occupy general positions. In the crystal structures, the complexes are packed in such a way that cavities are formed in which the solvent molecules are located. Compounds 1 and 2 are isotypic, which is not the case for compound 3. In compounds 1 and 2 the solvate molecules are disordered, whereas they are fully ordered in compound 3. Disorder is also observed for one of the 3-methylpyridine ligands in compound 2. Powder X-ray diffraction and IR measurements show that at room temperature all compounds decompose almost immediately into the same phase, as a result of the loss of the solvent molecules.

Keywords

• nickel(ii)thiocyanate
• 3-methylpyridine
• clathrates
• crystal structure