Spontaneous Redox Synthesis of the Charge Transfer Material TTF₄[SVMo₁₁O₄₀]

Abstract

The charge-transfer material TTF-SV(IV)Mo(11)O(40) (TTF = tetrathiafulvalene) was prepared by a spontaneous redox reaction between TTF and the vanadium-substituted polyoxometalate (n-Bu(4)N)(3)[SV(V)Mo(11)O(40)] in both solution and solid state phases. Single crystal X-ray diffraction gave the stoichiometry TTF(4)[SVMo(11)O(40)]·2H(2)O·2CH(2)Cl(2), with the single V atom positionally disordered with eight Mo atoms over the whole α-Keggin polyanion [SVMo(11)O(40)](4-). Raman spectra support the 1+ charge assigned to the oxidized TTF deduced from bond lengths, and elemental and voltammetric analysis also are consistent with this formulation. Scanning electron microscopy images showed a rod-type morphology for the new charge-transfer material. The conductivity of the solid at room temperature is in the semiconducting range. The TTF and (n-Bu(4)N)(3)[SV(V)Mo(11)O(40)] solids also undergo a rapid interfacial reaction, as is the case with TTF and TCNQ (TCNQ = tetracyanoquinodimethane) solids. EPR spectra at temperatures down to 2.6 K confirm the presence of two paramagnetic species, V(IV) and the oxidized TTF radical. Spectral evidence shows that the TTF-SV(IV)Mo(11)O(40) materials prepared from either solution or solid state reactions are equivalent. The newly isolated TTF-SV(IV)Mo(11)O(40) material represents a new class of TTF-polyoxometalate compound having dual electrical and magnetic functionality derived from both the cationic and anionic components.

Dinuclear Ruthenium Complex Based on a π-Extended Bridging Ligand with Redox-Active Tetrathiafulvalene and 1,10-Phenanthroline Units

“…In contrast to TTF-A, however, the bond lengths of the corresponding CC and C−S bonds for TTF-B are 1.347(3) Å (C111−C112) and 1.757 Å, respectively. On the basis of structural data, the charge-sensitive central CC bond lengths of the TTF cores [1.318(3) Å for TTF-A and 1.347(3) Å for TTF-B] are within the range of distances of neutral TTF molecules 11,25 and are far from the bond lengths of its radical cation (1.38−1.40 Å). 26 This result suggests that, in the solid state, steric effects in the dimer bring about a longer CC bond length and a shorter C−S bond length, instead of a radical state in TTF-B.…”

Voltammetric studies on the inter-relationship between the redox chemistry of TTF, TTF+˙, TTF2+ and HTTF+ in acidic media

“…Thus E m (1) ¼ À74 mV and E m (2) ¼ 311 mV vs. Fc 0/+ , respectively, so that these two processes are separated by E m (1) À E m (2) ¼ 385 mV. [22][23][24][25] From Fig. 1, it is apparent on the basis of the magnitudes of the relevant limiting, or peak, current values that the diffusion coefficient (D) for TTF is larger than that of TTF + c and TTF 2+ .…”

Spontaneous Redox Synthesis and Characterization of the Tetrathiafulvalene–Vanadium-Substituted Polyoxometalate Charge-Transfer Material TTF4[SVW11O40]: Comparison with the Mo Analogue

“…Magnetic susceptibility measurements were made with sample masses of ∼30 mg using a Quantum Design Model MPMS 5 SQUID magnetometer in dc magnetic fields of 0.01, 0.10, and 1.0 T. Diamagnetic and other corrections were made as described previously using Pascal’s constants and other published data as applicable. , …”

“…However, in principle, if the thermodynamics associated with reduction of POM anions can be set up appropriately, TTF-POM materials should become available by spontaneous reaction of TTF and POM, analogously to the reaction between TTF and TCNQ. This was achieved recently in the reaction of TTF and ( n -Bu 4 N) 3 [SVMo 11 O 40 ] . In this paper, it is now shown that the vanadium-substituted Keggin-type polyoxometalate ( n -Bu 4 N) 3 [SVW 11 O 40 ], synthesized by vanadium substitution in the parent ( n -Bu 4 N) 2 [SW 12 O 40 ] POM provides access to a V V/IV reduction process that has a more positive potential than that for the TTF 0/+ oxidation.…”