Molecular building blocks for magnetic spin chains

The paramagnetic di(metalloethynyl)benzene ion [1,4-C_6H_4{CW(depe)_2Cl}_2]^(2+) was synthesized from diamagnetic 1,4-C_6H_4{CW(depe)_2Cl}_2 (depe = 1,2-bis(diethylphosphino)ethane). Systematic measurements of magnetic susceptibility for both crystalline and powder-formed compounds indicate a predominant super-exchange coupling between the magnetic tungsten centres. We provide a quantitative description of the observed susceptibility using a decoupled Heisenberg dimer model, and find that all the complexes exhibit a robust antiferromagnetic coupling between spins, J~38 K. We note their potential use as building blocks for one-dimensional spin chains—with or without disorder—and describe possible synthetic routes to these architectures.