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

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−) ([FeCp 2 ] + [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.