1,2,4,5-Tetra([5]trovacenyl)benzene: an organometallic tetraradical displaying pronounced electro- and magnetocommunication

The organometallic tetraradical 1,2,4,5-[(eta)7-C7H7)V(all eta]5-C5H4)]4C6H2 has been prepared and structurally characterized. The isotropic EPR spectrum displays 29 a(51V) hyperfine lines, the intensity distribution slightly deviating from binomial. Exchange coupling therefore approaches the strong exchange limit, J(ortho) not equal to J(meta) not equal to J(para) greater or approximately 50 a(51V) with a(51V)= 0.0067 cm(-1). According to magnetic susceptometry, the interaction is antiferromagnetic. While redox splittings deltaE(1/2) are resolved for the four reduction steps this is not the case for oxidation.