Tetracyanoethylene anion radical

Triphenyl-X -phosphorin interacts with iodine or other polarizable electron donors, as well as with such electron acceptors as tetrachloro-p-benzoquinone and tetracyanoethylene, to produce deeply colored solutions. Such coloration points to the formation of charge-transfer complexes (see p. 43). In some cases electron transfer occurs with the formation of 2.4.6-triphenyl-X -phosphorin cation radical and tetracyanoethylene anion radical. Weber is currently investigating the details of these reactions (see p. 43). 

It resembles tetracyanoethylene in that it adds reagents such as hydrogen (31), sulfurous acid (31), and tetrahydrofuran (32) to the ends of the conjugated system of carbon atoms suffers displacement of one or two cyano groups by nucleophilic reagents such as amines (33) or sodiomalononittile (34) forms TT-complexes with aromatic compounds (35) and takes an electron from iodide ion, copper, or tertiary amines to form an anion radical (35,36). The anion radical has been isolated as salts of the formula (TCNQ) where is a metal or ammonium cation, and n = 1, 1.5, or 2. Some of these salts have... 

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... 

Dick turned up some interesting chemistry of caprolactam and its O-alkyl imino ethers. He and collaborators went on to explore the chemistry of allene, for example, its reactions with acetylene, carbon monoxide, and tetrafluo-roethylene. He did extensive work on the chemistry of cyclooctatetraene and of ferrocene. In the cyanocarbon area he collaborated on studies of the anion radical of tetracyanoethylene, that is, tetracyanoethylene bearing an extra electron. He was author or coauthor of 45 papers and 16 U.S. Patents that came out of the Central Research Department. 

It needs to be noted that Q + Q = Q + equilibrium is possible due to the rapid consumption of Q reducer. More often, the interaction of two identical ion-radicals can lead to their dimerization, but not disproportionation. For instance, the anion-radicals of tetracyanoethylene undergo dimerization (Lu et al. 2003). According to Miller and Novoa (2007), this dimerization proceeds as four-center carbon-carbon bonding. Rosokha and Kochi (2007) proposed the term n interaction for dimerization of the cation-radicals of tetrathiafulvalene. Because the n dimers are double-charged species, solvent polarity is essential for their formation. The n interaction overcomes the electrostatic repulsion, even in moderately polar enviromnents. 

The anion-radical of 2,4-dinitrochlorobenzene and cation-radical of triethylamine pass into the solvent volume. In this case, both acceptors (p-BQ, tetracyanoethylene, and tetracyanoquinodime-thide) and donors of an electron (potassium iodide, ferrous sulfate, and A/,N-tetramethyl-p-phenyl-enediamine) inhibit substitution (Shein 1983). 

Verdazyls (111) can also transfer an electron to o -quinones to give the verdazylium cation (113) and a semiquinone anion (114) (80IZV2785), or to tetranitromethane to give the cation (113) and the tetranitromethane anion radical (115) (74MI22100). Rate constants and activation parameters for the electron transfer from triphenylverdazyl to tetracyanoethylene have been determined by Soviet chemists (79ZOR2344). 

Tetracyanoethylene (TCNE), tetracyanoquinodimethane (TCNQ), and various mono-, di-, and trinitroaromatic compounds are the preferred electron-acceptor molecules for the detection of donor sites on oxide surfaces. Mostly TCNE has been used as a poison in catalytic research. Electronic and ESR spectra of the adsorbed acceptor molecules are characteristic of the surface anion radicals which are assumed to be formed according to... 

The most striking and nnexpected reactions of HO are those that prodnce anion radicals when hydroxide is added to solutions of aromatic ketones, quinones, paraquats, and strong electron acceptors such as tetracyanoethylene. If the primary reaction is a SET reaction, a radical pair will be produced (equation 181). 

The energy of the SOMO of an ethene derivative which is substituted with conjugating, electron withdrawing substituents is of course much lower than that of ethene itself. An extreme case of such an anion radical is that of tetracyanoethylene (TCNE), which has been isolated as the tetrabutylammonium salt. A reasonably direct, experimental examination of the SOMO distribution of this anion radical was possible through polarized single crystal neutron diffraction studies [108]. Interestingly, the pi SOMO was found not to be centered directly around the two alkene carbon nuclei, but rather to be bent back, away from the alkene C-C bond, as is theoretically expected for an MO which is anti-bonding between these two carbons (Scheme 65). 

ConTPP reacts with tetracyanoethylene (TCNE) to a 1 1 complex, where nitrogens of the nitrile groups interact with the cobalt (Eqn. 1). If pyridine is added to this complex, together with an excess of TCNE the molecule of TCNE is reduced by the Co11 to the anion radical (eqn. 2). 

Solvations of the charged species accelerate the transfer of electrons and the ionizations are enhanced by polar solvents.Charge transfer reaction studies with tetracyanoethylene, an acceptor, and A -vinyl carbazole, a donor, in benzene solution demonstrated that both cation radicals and anion radicals form. This can be used in a subsequent cationic polymerizations ... 

The first part of the underlying double square [46] scheme (10) contains a single electron transfer to the 7i(C=C) bonded tetracyanoethylene (TCNE) ligand in the blue complex with W(CO)5 which leads - in a relatively slow chemical reaction on the cyclovoltammetric time scale - to a yellow isomerized anion radical product in which TCNE coordinates via one nitrile nitrogen lone pair. The high resolution EPR, UVA is and infrared data of the singly reduced complex clearly illustrate the lowered symmetry and diminished n back donation in the secondary (TiO monoanionic form [46]. 

M.p. 296 C. Accepts an electron from suitable donors forming a radical anion. Used for colorimetric determination of free radical precursors, replacement of Mn02 in aluminium solid electrolytic capacitors, construction of heat-sensitive resistors and ion-specific electrodes and for inducing radical polymerizations. The charge transfer complexes it forms with certain donors behave electrically like metals with anisotropic conductivity. Like tetracyanoethylene it belongs to a class of compounds called rr-acids. tetracyclines An important group of antibiotics isolated from Streptomyces spp., having structures based on a naphthacene skeleton. Tetracycline, the parent compound, has the structure ... 

Radical anions of tetracyanoethylene and trinitrobenzene have been observed on Ti02 and MgO. For nitro-benzene compounds adsorbed on well-degassed MgO, Tench and Nelson (90) reported spectra similar to those observed for the radical anions on alumina and silica-alumina. After discussing several possibilities for the source of electrons in MgO they suggested that some of the lattice oxide ions may act as electron donors. One of the difficulties with this proposal is the failure to detect the resulting... 

An updated book on organic radical ions3 comprises an extensive (presumably almost complete) set of hyperfine data and summarizes methods for their generation. Another book concentrates on chemical properties of radical ions4. Valuable information on timescales and the energetics leading to the dimerization of radical anions and cations (and neutral radicals) based on tetracyanoethylene, tetracyanoquinodimethane, substituted benzoquinones (DDQ and chloranil) as acceptors and octamethylbiphenylene is reported by Kochi and coworkers5. 

Only in exceptional circumstances are aliphatic radicals sufficiently stable to be prepared in solution. Notable amongst those that have been studied is the anion of tetracyanoethylene (Phillips et al., 1960) and the ketyls (Hirota and Weissman, 1960) [(Me3C)2CO] and [Me3C.CO.CHMe2]. The anion of tetracyanoethylene is readily formed in aqueous solution by the action of such mild reducing agents as iodide ion. The ketyls were prepared at low temperature in metal-ether solutions, and are relatively unstable. 

Cathodic reduction of 1,1,2,2-tetracyanocyclopropane or 1,1,2,2,-tetracyano-ethane yields the radical anion of tetracyanoethylene via a formal reductive de-methylenation and dehydrogenation, respectively (Eq. (256) ) 592K... 

Tetracyanoethylene (TCNQ) shown below is a highly conjugated planar molecule. Its ir-type LUMO (represented below) lies at a rather low energy so that the compound can be easily reduced by one electron, giving rise to the stable radical anion TCNQ-. 

The Si-Si bond provided the first example of a a-bond donor in the formation of charge-transfer complexes with TCNE (tetracyanoethylene). Conversely, the Si-Si bond can act as an electron acceptor to form disilanyl radical anions. 

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