Paramagnetic and Semiconducting 1:1 Salts of 1,1‘-Disubstituted Ferrocenes and [Ni(mnt)2]-. Synthesis, Structure, and Physical Properties

Abstract

The ferrocene-based electron donors 1,1‘-bis[2-(4-(methylthio)phenyl)-(E)-ethenyl]ferrocene (2), 1,1‘-bis[2-(4-methoxyphenyl)-(E)-ethenyl]ferrocene (3), 1,1‘-bis[(1,3-dithiolo[4,5-b][1,3]dithiol-2-ylidene)methyl]ferrocene (4), and 1,1‘-bis[(1,3-benzodithiol-2-ylidene)methyl]ferrocene (5) were found to react with ferrocenium bis(maleonitriledithiolato)nickelate (1−) ([FeCp2]+[Ni(mnt)2]-, 6) to afford the corresponding 1:1 paramagnetic salts 7−10, containing 1,1‘-disubstituted ferrocenium derivatives. SQUID magnetic susceptibility measurements of these new compounds showed a behavior dominated by antiferromagnetic interactions within pairs of [Ni(mnt)2]- ions. Pressed pellets of compounds 7 ([2][Ni(mnt)2]) and 9 ([4][Ni(mnt)2]) are semiconducting, with a relatively large conductivity activation energy (0.85 and 1.13 eV). Crystals of 7 reveal the monodimensional nature of the compound. Each separate stack of [Ni(mnt)2]- ions is flanked by two ferrocenium stacks. Ni−Ni distances alternate between 3.67 and 3.99 Å.