Synthesis and Characterization of Charge Transfer Salts Based on [M(dcdmp)2] (M = Au, Cu and Ni) with TTF Type Donors

Abstract

The charge transfer salts α-DT-TTF[Au(dcdmp) 2 ] (1), BET-TTF[Au(dcdmp) 2 ] (2M and 2T), α-DT-TTF[Cu(dcdmp) 2 ] (3), ET[Cu(dcdmp) 2 ] (4), (BET-TTF) 2 [Cu(dcdmp) 2 ] (5), (ET) 2 [Ni(dcdmp) 2 ] (6), and α-mtdt[Cu(dcdmp) 2 ] (7) were obtained by electrocrystallization of different electron donor molecules derived from TTF (α-DT-TTF = alpha-dithiophene-tetrathiafulvalene; BET-TTF = (bis(ethylenethio)tetrathiafulvalene; ET = bis(ethylenedithio)-tetrathiafulvalene; α-mtdt = alpha-methylthiophenetetrathiafulvalene) in the presence of transition metal complex [M(dcdmp) 2 ] (M = Au (III), Cu (III) and Ni (II)) (dcdmp = 2,3-dicyano-5,6-dimercaptopyrazine). Compounds 1 and 2 (2M and 2T) have a similar packing pattern composed of mixed stacks of alternating donor-acceptor molecules. For (BET-TTF)[Au(dcdmp) 2 ] two different crystal structures (2M and 2T) were obtained indicating polymorphism. Compounds 3 and 4 are isostructural being composed of zigzag chains of alternating donor and acceptor molecules. The salts with a 2:1 stoichiometry, (BET-TTF) 2 [Cu(dcdmp) 2 ] (5), and (ET) 2 [Ni(dcdmp) 2 ] (6) present the donor molecules fully oxidized and [M(dcdmp) 2 ] (M = Ni and Cu) in a dianionic state. The salt of the dissymmetric donor α-mtdt with [Cu(dcdmp) 2 ], α-mtdt[Cu(dcdmp) 2 ] (7) has a crystal structure composed of segregated donor stacks that are positioned in a head-to-head fashion and alternate with the anion stacks. All charge transfer salts (1-7) are modest semiconductors with conductivities in the range 10 −1-10 −5 S/cm, with the highest values obtained in α-DT-TTF salts, compounds 1 and 3.

Rational Design of Proton–Electron-Transfer System Based on Nickel Dithiolene Complexes with Pyrazine Skeletons

“…Along the side-by-side direction ( a axis), Ni II (Hdcpdt) 2 molecules are connected to orientationally disordered Et 2 O molecules by N–H···O hydrogen bonds with N···O distances of 2.668–2.688 Å (sum of the van der Waals radii: 3.07 Å) to form the ladder structure (Figure a). The complex involves π-stacking columns, in contrast to salts composed of 1­(II)-0H , ,, along the b axis (Figure b) with an interplanar distance of 3.536 Å in a sliding manner (Figure c). Although efforts to chemically isolate the PET-state solid, 1­(III)-1H , have been unsuccessful at present, these crystallographic features suggest that there is some hope of realizing the PET state with π-stacking columns that are connected to each other with hydrogen bonds.…”

Recent advances in the mechanisms of the hydrogen evolution reaction by non-innocent sulfur-coordinating metal complexes

“…Thus, these systems display interesting chemical properties such as ferromagnetism, spin-ladder behavior, superconducting properties and catalytic activity. [45][46][47] Since non-innocent ligands store reducing equivalents in the catalytic complex, they can lower the required overpotential to form hydrogen from solution protons. Elucidation of the nature of the metal-sulfur bond is important in gaining insight into the structure/function relationships of thiolate catalysts.…”

“…The authors suggest that the reduced fluorescein transfers an electron to the protonated catalyst and hydrogen is evolved via a pathway similar to that of catalyst 30. 160 The cobalt analogue of complex 40, cobalt bipyridine pyridine-thiolate (45) and cobalt 1,10-phenanthroline pyridine-thiolate (46) were used as photocatalysts in the above system, reaching 210.3 and 163.2 μmol h −1 of hydrogen evolution. 161 The group of Eisenberg also studied the catalytic activity of the nickel thiolate complexes 47-49 (Scheme 21a).…”

The Stoichiometry of TCNQ-Based Organic Charge-Transfer Cocrystals

“…There are many papers related to charge transfer cocrystals published in several special issues of the journal Crystals covering different aspects, including donor-acceptor packing type of co-crystals [43,44], hydrogen-bonded co-crystals [45,46], conducting and superconducting co-crystals [47,48], etc. However, it is still worth discussing the role of stoichiometry between donor and acceptor in co-crystals.…”