Multidimensional assemblies consisting of paramagnetic metal ions and polycyano organic acceptor molecules are being prepared in an effort to access molecule-based magnetic/conducting materials based on dp ± pp electronic interactions. [1±4] Achieving high conductivity through the backbone of a metalloorganic polymer is one of the most challenging goals, and one that has been realized in only one case, namely in the [Cu(DCNQI) 2 ] I family of compounds (DCNQI N,N'dicyanoquinonediimine). [5] These materials consist of a threedimensional skeleton containing tetrahedral mixed-valence Cu I /Cu II ions connected by partially reduced DCNQI radicals arranged in p-stacked columns throughout the three-dimensional network. Although the latter structural feature is a main contributor to the conducting pathway, it has been demonstrated that delocalization through the Cu ± DCNQI skeleton is crucial for stabilizing the metallic state of these materials.
The use of electron-rich dimetal complexes to prepare dp ± pp delocalized systems began in our laboratories with the isolation of the ªdimer-of-dimersº [{Re 2 Cl 4 (dppm) 2 } 2 (m-TCNQ)]
(dppm 1,2-bis(diphenylphosphanyl)methane, TCNQ 7,7,8,8-tetracyanoquinodimethane). This compound is the first example of a charge transfer complex of TCNQ with a metal ± metal-bonded donor. The presence of the oxidized Re ± Re species (s 2 p 4 d 2 d* 1 ) and reduced TCNQ .À was confirmed by spectroscopic and magnetic studies. [6] In this 2:1 donor ± acceptor system, electronic delocalization is favored through good metal dp/organic pp overlap; this can be represented by the resonance structures: [Re II;III 2 -(TCNQ .À )-Re II;II 2 ] (1) > Re II;II 2 -(TCNQ)-Re II;II 2 ] (2) > [Re II;II 2 -(TCNQ .À )-Re II;III 2 ] (3), with forms 1 and 3 being the main contributors.
A logical extension of the aforementioned chemistry is the construction of networks based on electron-rich Ru II /Ru II complexes. This idea is predicated on the notion that the dp orbitals on Ru II /Ru III and the pp orbitals of the TCNQ ligands will be energetically compatible; indeed there is ample
[*] Prof.