Quasi-one-dimensional (Q1D) organic Mott insulators based on bent donor molecule EDO-EDSe-TTFVS

A series of conducting quasi-one-dimensional (Q1D) cation radical salts based on a bent donor molecule EDO-EDSe-TTFVS (1), 1(2)ClO(4), 1(2)PF(6)(PhCl)(0.25), and 1(2)AsPF(6)(PhCl)(0.25), were obtained via electrocrystallization. These salts show the semiconducting behavior with moderate conductivities up to 4.0 S cm(-1) and relatively large magnetic susceptibilities of 9 x 10(-4) emu mol(-1). The temperature dependent magnetic susceptibilities of these salts can be well fitted by the one-dimensional Heisenberg antiferromagnetic chain model. In their crystal structures, two donor molecules are crystallographically independent, while they are in the same oxidation state of +0.5 judging from their C=C double bond lengths. The donor molecules form columnar stacks composed of donor dimers, and the size of the counter ion plays an important role on the degree of donor molecule dimerization. The electronic bands of these salts substantially split into the upper and lower two bands, and the upper bandwidth (W-U) is smaller than on-site Coulomb repulsion of donor dimer (U-dimer), W-U/U-dimer <0.85. These salts are intrinsically Mott insulators. (C) 2012 Elsevier B.V. All rights reserved.