Preparation and solid-state structural, electronic, and magnetic properties of the 5-cyano-1,3-benzene-bridged bis(1,2,3,5-dithiadiazolyl) and bis(1,2,3,5-diselenadiazolyl) [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se)

Abstract

The preparation and solid-state characterization of the bifunctional radicals [4,4’-(5-cyanobenzene)-1,3-bis(1,2,3,5-dithiadiazolyl)] and [4,4’-(5-cyanobenzene)-1,3-bis( 1,2,3,5-diselenadiazolyl)] [5-CN-1,3-C6H3(CN2E2)2] (E = S, Se) are described. The crystals of the two title compounds are isomorphous and belong to the monoclinic space group P21/c, with (for E = S) a = 7.00(2), b = 30.050(6), c = 10.713(8) Å, β = 104.80(10)°, V = 2179(6) Å3, Z = 8 and (for E = Se) a = 7.124(4), b = 30.50(2), c = 10.874(2) Å, β = 105.46(3)°, V = 2277(2) Å3, Z = 8. The crystal structures consist of stacks of diradicals running parallel to x; radical dimerization up and down the stack generates a zigzag arrangement, as seen in the related 1,3-phenylene structures. Along the stacking axis the mean intradimer E-E contacts are 3.12 (E = S) and 3.23 Å (E = Se), while the mean interdimer E- - -E distances are 3.89 (E = S) and 3.91 Å (E = Se). Magnetic and conductivity data are presented and discussed in light of extended Hückel band structure calculations.