Coordination Networks from [Te4]2+ Clusters and Polynitriles

The reactions of a series of organic polynitriles with [Te-4][AsF6](2) in liquid SO2 solution lead either to reduction of [Te-4](2+) to elemental tellurium or to the formation of coordination polymers. With 1,3-dicyanobenzene (1,3-DCB), 1,4-dicyanobenzene (1,4-DCB), 1,2,4,5-tetracyanobenzene (TCB), tetracyanoethylene (TCNE) and tetracyanochinodimethane (TCNQ) the coordination complexes [Te-4][AsF6](2) & sdot; 2(1,3-DCB), [Te-4][AsF6](2) & sdot; 3(1,4-DCB) & sdot; 2SO(2), [Te-4][AsF6](2) & sdot; TCB, [Te-4][AsF6](2) & sdot; TCNE and [Te-4][AsF6](2) & sdot; TCNQ & sdot; 8 SO(2 )were isolated and characterized by crystal structure analyses and vibrational Raman spectroscopy. The nitriles are coordinated to the square-planar clusters forming 1D chains, 2D arrangements and 3D networks. Tetrakis(dicyanomethylene)cyclobutendiide [C-4(C{CN}(2))(4)](2-) is oxidized by [Te4]2+ to the neutral cyanocarbon C-4(C{CN}(2))(4), structurally representing a 4[radialene]. The ionization potentials and electron affinities of the cyanamide anion, cyanogen, 1,2-DCB, 1,3-DCB, 1,4-DCB, TCB, C-4(C{CN}(2))(4), TCNE and TCNQ and those polynitriles, which cause reduction of [Te-4](2+), were calculated at coupled-cluster level of theory in order to examine possible reasons for the stability of the coordination polymers based on electronic properties of the nitriles.