Tetrakis([5]trovacenyl)tin: Synthesis, Structure, and Intramolecular Communication†

In order to study intermetallic interactions in a tetranuclear complex with tetrahedral disposition of paramagnetic central metal atoms, the organometallic tetraradical [(η7-C7H7)V(η5-C5H4)]4Sn (34•), tetra([5]trovacenyl)tin, was prepared, characterized by X-ray diffraction, and subjected to EPR spectroscopy, magnetic susceptometry, and cyclic voltammetry. The binuclear complex [(η7-C7H7)V(η5-C5H4)]2Ph2Sn (42•) was also obtained to serve as a reference molecule. The EPR hyperfine pattern attests to exchange coupling which approaches the fast exchange limit, i.e., JEPR (34•) ≫ a(51V) = 0.0067 cm-1. For the dinuclear complex simulation afforded the value |J(42•)| = 1.4 cm-1; magnetic susceptometry yielded the exchange coupling constant Jχ(42•) = −1.78 cm-1. No quantitative data could be derived for the tetranuclear complex; however, the gradation J(34•) J(42•) applies. This may be a result of competing interactions of opposite sign or of spin frustration, as has been discussed previously for tetrahedral spin clusters of the Werner type. Redox splittings for tetrakis([5]trovacenyl)tin are smaller than those for tetrakis(ferrocenyl)silicon.