Long chain defective metal string complex with modulated oligo-α-pyridylamino ligand: Synthesis, crystal structure and properties

Abstract

Through a pyrimidine and naphthyridine-containing triamine ligand, N2-(pyrimidin-2-yl)-N7-(2-(pyrimidin-2-ylamino)-1,8-naphthyridin-7-yl)-1,8-naphthyridine-2,7-diamine (H3N9-2pm), defective metal string complex [Ni8.33(N9-2pm)4(NCS)2](PF6)2 (1) was successfully synthesized and structurally characterized. The complex consists of a linear metal chain and four deprotonated supporting ligands which are helically wrapped around the metal score. X-Ray crystallographic studies revealed that the complex (1) crystallizes in space group P21/c of the monoclinic system. The small J value (J = −2.90 cm−1) suggests quite a weak magnetic interaction throughout the molecule of complex (1). The weak magnetic interaction in the defective complex indicates that the spin exchange in metal string occurs through the metal core rather than the bridging ligands. The electrochemical study on complex 1 shows abundant redox properties and facility to the reduction in its cyclic voltammogram by displaying three reversible redox couples at E1/2 = - 0.35, - 0.69 and – 0.88 V.