Abstract

The sandwich complex -3{,}3prime or minute]-Fe1-(CHS)-1,2-CBH] and its tetrathiafulvalenium salts ttfFe(CBHCHS) and ttfFe(CBHCHS) were synthesised in order to study the effect of the thiophene (CHS) group on the crystal packing{,} electrical and magnetic properties of ttf-metallacarborane salts. The crystal structure of features unusual two-dimensional networks of ttf units which extend in the and directions. Each ttf sheet contains stacked trimers of ttf units{,} which propagate along the direction{,} and bridging ttf units{,} which lie between the ttf stacks approximately orthogonally to the ttf units within the trimers. The trimers are linked along the direction short S S contacts (3.56 A) with these bridging ttf units. In contrast{,} the crystal structure of compound contains discrete stacked dimers of ttfradical dot cations. Whilst crystals of are semiconducting (sigma= 2 times 10 S cm) with an activation energy of 0.22 eV{,} those of are insulating (sigmaless-than-or-eq 10 S cm). Both compounds exhibit weak ferromagnetic interactions between the unpaired spins of their Fe(CBHCHS) anions{,} with small positive Weiss constants of 1.9 and 0.5 K respectively.