Tetracyanoquinodimethane structure

Although organic anion radicals are oxygen sensitive, they have been isolated as crystalline salts from a variety of electron acceptors (e.g., chloranil, tetracyanoethylene, tetracyanoquinodimethane, perylene, naphthalene, anthracene, tetraphenylethylene, etc.) and their structures have been established by X-ray crystallography.180... 

Fe(abptrz)2(tcnq)2] is an iron(II) complex of the triazole 4-amino-3,5-bis(pyridin-2-yl)-1,2,4-triazole (abptrz) and the 7,7, 8,8 -tetracyanoquinodimethane (tcnq) radical anion whose structure, (132), Mossbauer and IR spectra, and magnetic behavior (thermally induced (280 K) spin crossover -S = 2 -S = 0) have been established. " ... 

Morita Y, Miyazaki E, Umemoto Y, Fukui K, Nakasuji K (2006) Two-dimensional networks of ethylenedithiotetrathiafulvalene derivatives with the hydrogen-bonded functionality of uracil, and channel structure of its tetracyanoquinodimethane complex. J Org Chem 71 5631-5637... 

Murata T, Saito G, Nishimura K, Enomoto Y, Honda G, Shimizu Y, Matsui S, Sakata M, Drozdova 00, Yakushi K (2008) Complex formation between a nucleobase and tetracyanoquinodimethane derivatives crystal structures and transport properties of charge transfer solids of cytosine. Bull Chem Soc Jpn 81 331-344... 

In the case of the trinuclear [ t-N1,C2-bzimAu]3 (bzim = benzylimidazolate), in addition to the extended structures that form with other metals (see Section 6.3), it also forms supramolecular networks, acting as an electron donor with small organic acids [48]. For example, it reacts with TCNQ (tetracyanoquinodimethane) giving rise to a columnar structure in which each TCNQ molecule is sandwiched between two units of the trinuclear complex in a face-to-face manner. Thus, the repetition of this pattern leads to a stacking of the type (Au3)(Au3)( t-TCNQ)(Au3)... 

All of the complexes are square planar unless otherwise stated the structures have been determined by X-ray analysis. Bond distances are in pm and nctl in BM. TCNQ is tetracyanoquinodimethane. 

Since mainly the E° of the mediator dictates at what potential the heterogenous electron transfer occurs, the oxidation of NADH can now take place at a much lower potential. The different mediator structures used to produce CMEs for NADH oxidation at a decreased overpotential are summarized in Table I. As is seen in the table, not only chemically modified electrodes based on only immobilized redox mediators have been used for this purpose, but also electrodes based on the combination of redox mediators and NADH oxidizing enzymes (diaphorase and NADH dehydrogenase) as well as electrodes made of the conducting radical salts of tetrathiafulvalinium-7,7,8,8-tetracyanoquinodimethan (TTF-TCNQ) and W-methyl-phenazin-5-ium-7,7,8,8-tetracyanoquinodimethan (NMP-TCNQ). 

Figure 6.8 Chemical structures of some common redox mediators (a) dimethyl ferrocene (b) tetrathiafulvalene (c) tetracyanoquinodimethane (d) Meldola Blue.

The structures of polymers containing benzobisthiazole and benzobisoxazole have been determined. These form rigid rod-like polymers with high specific strength <81MM935>. For some bis-selenadiazolo analogues of tetracyanoquinodimethane x-ray methods established the presence of extensive intermolecular interactions <87CL2285>. 

Only a few X-ray crystal structure determinations on 1,3-dithioles have been carried out. Some typical bond lengths and bond angles of the tetrathiafulvalene (5), l,3-dithiole-2-thione derivative (6) and 1,3-dithiolanes (7) and (8) are given in Tables 2 and 3, respectively. Also bond lengths and bond angles of the radical cation of tetrathiafulvalene in the tetrathiafulvalene-7,7,8,8-tetracyanoquinodimethane complex have been determined <74AX(B)763>. 

V. Malatesta, R. Millini, and L. Montanari, Key intermediate product of oxidative degradation of photochromic spiro-oxazines. X-ray crystal structure and electron spin resonance analysis of its 7,7,8,8-tetracyanoquinodimethane ion-radical salt, J. Am. Chem. Soc., 117, 6258-6264 (1995). 

Tetracyanoethylene (tone) and 7,7,8,8-tetracyanoquinodimethane (tcnq) both form adducts with stannocene and plumbocene that are of uncertain structure. The stannocene derivatives SnCp2 (tcne) (n = 1 or 2) and SnCp2 (tcnq) are proposed to be cyclopentadienyl 7r-charge transfer complexes (42). The plumbocene derivatives PbCp2(tcne) (n = 0.5 or 1) and PbCp2(tcnq) apparently involve charge transfer and are proposed to be polymeric (41). 

Suzuki et al. reported the photochemical reaction of CT crystals, in which cycloaddition reaction of bis(l,2,5-thiadiazolo)tetracyanoquinodimethane 10 (electron acceptor) and 2-divinylstylene 11 (electron donor) is efficiently induced (Scheme 6) [14]. The structural feature of the CT crystal is the asymmetric nature of the inclusion lattice because of the adoption of a chiral space group, P2. The [2 + 2] photoadduct was formed via the single crystal-to-single crystal transformation, and the optically active product with 95% ee was obtained. 

In the above radical-cation salts, the crystal contains partially oxidized donors, while the electroneutrality is achieved by the presence of closed shell anions. The structural requirements necessary for electrical conductivity in solid salts can also be met upon mixing of donors and acceptors in the resulting charge-transfer (CT) complexes both the donor and acceptor exist in a partially oxidized and reduced state, respectively. Famous examples are the conducting CT complexes formed upon mixing of perylene (112) [323. 324] and iodine or of tetrathiafulvalene (TTF, 119) as donor and 7,7,8,8-tetracyanoquinodimethane (TCNQ, 120) as acceptor [325-327] the crucial structural finding for the... 

Fig. 6.2 Views of the two polymorphic structures of 6-II 6-III. In both cases the view is on the plane of the tetracyanoquinodimethane molecule 6-II. (a) The red, transparent, mixed-stack complex, a semiconductor (b) the black opaque, segregated stack complex, a conductor. (From Bernstein 99 b, with permission.)...

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