TCNE) And 7,7,8,8-tetracyanoquinodimethane Research Articles

Near‐IR Intramolecular Charge Transfer in Strongly Interacting Diphenothiazene‐TCBD and Diphenothiazene‐DCNQ Push‐Pull Triads

AbstractThree types of phenothiazines dimers (PTZ‐PTZ, 1–3), covalently linked with one or two acetylene linkers, were synthesized by copper‐mediated Eglinton and Pd‐catalyzed Sonogashira coupling reactions in excellent yields. The dimers 1–3 were further engaged in [2+2] cycloaddition‐retroelectrocyclization reactions with strong electron acceptors, tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) to yield tetracyanobutadiene (TCBD, 1 a–3 a), and dicyanoquinodimethane (DCNQ, 1 b–3 b) functionalized donor‐acceptor (D‐A) conjugates, respectively. The conjugates were examined by a series of spectral, computational, and electrochemical studies. Strong ground state polarization leading to new optical transitions was witnessed in both series of D‐A conjugates. In the case of DCNQ derived D‐A system 1 b, the optical coverage extended until 1200 nm in benzonitrile, making this a rare class of D‐A ICT system. Multiple redox processes were witnessed in these D‐A systems, and the frontier orbitals generated on DFT optimized structures further supported the ICT phenomenon. Photochemical studies performed using femtosecond pump‐probe studies confirmed solvent polarity dependent excited state charge transfer and separation in these novel multi‐modular D‐A conjugates. The charge‐separated states lasted up to 70 ps in benzonitrile while in toluene slightly prolonged lifetime of up to 100 ps was witnessed. The significance of phenothiazine dimer in wide‐band optical capture all the way into the near‐IR region and promoting ultrafast photoinduced charge transfer in the D‐A‐D configured multi‐modular systems, and the effect of donor‐acceptor distance and the solvent polarity was the direct outcome of the present study.

Effect of electron donor and acceptor on the photovoltaic properties of organic dyes for efficient dye-sensitized solar cells

In this work, the molecular engineering approach was applied to the organic dyes of AE, AQ, TE, and TQ having the donor-acceptor (D-A) configuration to investigate the solar cell efficiency. In these structures, dimethylaniline and triphenylamine were used as the electron donors and 1,1,4,4-tetracyanobuta-1,3-dienes (originating from TCNE) and 2-(4-(4,4-dicyanobut-3-en-2-ylidene)cyclohexa-2,5-dien-1-ylidene)malononitrile (originating from TCNQ) as the electron acceptors. The incorporation of tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) due to the strong electron-withdrawing ability enhance the performance of the dye-sensitized solar cell (DSSC). The results reveal that a change in the electron donor and acceptor moieties affects the photovoltaic processes. Also, the dyes having 2-(4-(4,4-dicyanobut-3-en-2-ylidene)cyclohexa-2,5-dien-1-ylidene)malononitrile electron acceptor (AQ and TQ) have better charge transfer indices such as longer charge transfer distance (DCT) and lower overlap of electron-hole distribution (S) in comparison with the dyes having 1,1,4,4-tetracyanobuta-1,3-dienes as an electron acceptor (AE and TE). Moreover, the properties of the absorption spectra indicate that TCNQ-adduct dyes (AQ and TQ) illustrate a red-shift compared with TCNE-adduct dyes (AE and TE) due to the higher ability of the electron-withdrawing. Finally, AQ and TQ dyes are the preferred candidates to improve the efficiency of the studied DSSCs because of higher charge transfer, electron transfer rate constant, and lower chemical hardness.

Triphenylamine-Merocyanine-Based D1-A1-π-A2/A3-D2 Chromophore System: Synthesis, Optoelectronic, and Theoretical Studies.

donor–acceptorDonor–acceptor–π–acceptor–donor (D1-A1-π-A2/A3-D2)-type small molecules, such TPA-MC-2 and TPA-MC-3, were designed and synthesized starting from donor-substituted alkynes (TPA-MC-1) via [2 + 2] cycloaddition−retroelectrocyclization reaction with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) units, respectively. TPA-MC-2 and TPA-MC-3 chromophores differ on the A2/A3 acceptor subunit, which is 1,1,4,4-tetracyanobutadiene (TCBD) and a dicyanoquinodicyanomethane (DCQDCM), respectively. Both the derivative bearing same donors D1 (triphenylamine) and D2 (trimethylindolinm) and also same A1 (monocyano) as an acceptor, tetracyano with an aryl rings as the π-bridging moiety. The incorporation of TCNE and TCNQ as strong electron withdrawing units led to strong intramolecular charge-transfer (ICT) interactions, resulting in lower LUMO energy levels. Comparative UV–Vis absorption, fluorescence emission, and electrochemical and computational studies were performed to understand the effects of the TCNE and TCNQ subunits incorporated on TPA-MC-2 and TPA-MC-3, respectively.

Strong Ground‐ and Excited‐State Charge Transfer in C3‐Symmetric Truxene‐Derived Phenothiazine‐Tetracyanobutadine and Expanded Conjugates

AbstractThe C3‐symmetric star‐shaped phenothiazene‐substituted truxene 1 was reacted with the electron acceptors tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ). The cycloaddition–retroelectrocyclization reaction yields the conjugates 2 and 3. A combination of spectral, electrochemical, and photophysical investigations of 2 and 3 reveals that the functionalization of the triple bond has a pronounced effect on their ground and excited‐state interactions. Specifically, the existence of strong ground‐state interactions between phenothiazine and the electron‐accepting groups results in charge‐transfer states, while subsequent ultrafast charge separation yields electron transfer products. This is unprecedented not only in phenothiazine chemistry but also in tetracyanobutadiene‐ and dicyanoquinodimethane‐derived donor–acceptor conjugates. Additionally, by manipulating spectroelectrochemical data, a spectrum of the charge‐separated species is construed for the first time, and shown to be highly useful in interpreting the rather complex transient spectra.

Strong Ground- and Excited-State Charge Transfer in C3 -Symmetric Truxene-Derived Phenothiazine-Tetracyanobutadine and Expanded Conjugates.

The C3 -symmetric star-shaped phenothiazene-substituted truxene 1 was reacted with the electron acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The cycloaddition-retroelectrocyclization reaction yields the conjugates 2 and 3. A combination of spectral, electrochemical, and photophysical investigations of 2 and 3 reveals that the functionalization of the triple bond has a pronounced effect on their ground and excited-state interactions. Specifically, the existence of strong ground-state interactions between phenothiazine and the electron-accepting groups results in charge-transfer states, while subsequent ultrafast charge separation yields electron transfer products. This is unprecedented not only in phenothiazine chemistry but also in tetracyanobutadiene- and dicyanoquinodimethane-derived donor-acceptor conjugates. Additionally, by manipulating spectroelectrochemical data, a spectrum of the charge-separated species is construed for the first time, and shown to be highly useful in interpreting the rather complex transient spectra.

NIR-Absorbing Donor-Acceptor Based 1,1,4,4-Tetracyanobuta-1,3-Diene (TCBD)- and Cyclohexa-2,5-Diene-1,4-Ylidene-Expanded TCBD-Substituted Ferrocenyl Phenothiazines.

A series of unsymmetrical (D-A-D1 , D1 -π-D-A-D1 , and D1 -A1 -D-A2 -D1 ; A=acceptor, D=donor) and symmetrical (D1 -A-D-A-D1 ) phenothiazines (4 b, 4 c, 4 c', 5 b, 5 c, 5 d, 5 d', 5 e, 5 e', 5 f, and 5 f') were designed and synthesized by a [2+2] cycloaddition-electrocyclic ring-opening reaction of ferrocenyl-substituted phenothiazines with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The photophysical, electrochemical, and computational studies show a strong charge-transfer (CT) interaction in the phenothiazine derivatives that can be tuned by varying the number of TCNE/TCNQ acceptors. Phenothiazines 4 b, 4 c, 4 c', 5 b, 5 c, 5 d, 5 d', 5 e, 5 e', 5 f and 5 f' show redshifted absorption in the λ=400 to 900 nm region, as a result of a low HOMO-LUMO gap, which is supported by TD-DFT calculations. The electrochemical study exhibits reduction waves at low potential due to strong 1,1,4,4-tetracyanobuta-1,3-diene (TCBD) and cyclohexa-2,5-diene-1,4-ylidene-expanded TCBD acceptors. The incorporation of cyclohexa-2,5-diene-1,4-ylidene-expanded TCBD stabilized the LUMO energy level to a greater extent than TCBD.

Unsymmetrical and Symmetrical Push-Pull Phenothiazines.

A series of unsymmetrical and symmetrical push-pull phenothiazines (3-7) were designed and synthesized by the Pd-catalyzed Sonogashira cross-coupling reaction and subsequent [2 + 2] cycloaddition-retroelectrocyclization reaction with tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The effect of systematic variation of the number and nature of cyano-based acceptor TCNE and TCNQ units on the photophysical, electrochemical, and computational studies was investigated. The single-photon absorption on phenothiazines 3-7 reveals that substitution of 1,1,4,4-tetracyanobutadiene (TCBD) and a cyclohexa-2,5-diene-1,4-diylidene-expanded TCBD unit results in strong intramolecular charge transfer and lowering of the LUMO energy level. The TCBD-linked and cyclohexa-2,5-diene-1,4-diylidene-expanded TCBD-linked phenothiazines 3-7 exhibit multiredox waves. The computational studies on phenothiazines 3-7 exhibit substantial stabilization of the LUMO with the increase in acceptor strength, which results in lowering of the HOMO-LUMO gap.

Analytical studies on the charge transfer complexes of loperamide hydrochloride and trimebutine drugs. Spectroscopic and thermal characterization of CT complexes

Charge transfer complexes of loperamide hydrochloride (LOP.HCl) and trimebutine (TB) drugs as electron donor with 2,3-dichloro-5,6-dicyano-p-benzoquinone (DDQ), tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) as π-acceptors in acetonitrile were investigated spectrophotometrically to determine the cited drugs in pure and dosage forms. The reaction gives highly coloured complex species which are measured spectrophotometrically at 460, 415 and 842nm in case of LOP.HCl and at 455, 414 and 842nm in case of TB using DDQ, TCNE and TCNQ reagents, respectively. The optimum experimental conditions have been studied carefully and optimized. Beer’s law was obeyed over the concentration ranges of 47.70–381.6, 21.50–150.5 and 10.00–100.0μgmL−1 for LOP.HCl and 37.85–264.9, 38.75–310.0 and 7.75–155.0μgmL−1 for TB using DDQ, TCNE and TCNQ reagents, respectively. Sandell sensitivity, standard deviation, relative standard deviation, limit of detection and quantification were calculated. The obtained data refer to high accuracy and precision of the proposed method. These results are also confirmed by inter and intra-day precision with percent recovery of 99.18–101.1% and 99.32–101.4% in case of LOP.HCl and 98.00–102.0% and 97.50–101.4% in case of TB using DDQ, TCNE and TCNQ reagents for intra- and inter-day, respectively. These data were compared with those obtained using official methods for the determination of the cited drugs. The stability constants of the CT complexes were determined. The final products of the reaction were isolated and characterized using FT-IR, 1H NMR, elemental analysis and thermogravimetric analysis (TG). The stoichiometry and apparent formation constant of the complexes formed were determined by applying the conventional spectrophotometric molar ratio method.

Synthesis and Properties of Azulene‐Substituted Donor–Acceptor Chromophores Connected by Arylamine Cores

Abstract1‐Ethynylazulenes connected by several arylamine cores reacted with tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ) in a formal [2+2] cycloaddition–cycloreversion reaction to afford the corresponding tetracyanobutadiene (TCBD) and dicyanoquinodimethane (DCNQ) chromophores, respectively, in excellent yields. The intramolecular charge‐transfer (ICT) characters between the donor (azulene and arylamine cores) and acceptor (TCBD and DCNQ units) moieties were investigated by UV/Vis spectroscopy and theoretical calculations. The redox behavior of the new TCBD and DCNQ derivatives was examined by cyclic voltammetry (CV) and differential pulse voltammetry (DPV), which revealed their multistep electrochemical reduction properties. Moreover, significant color changes were observed by visible spectroscopy under the electrochemical reduction conditions.

Synthesis, spectroscopic and structural characterization of charge transfer complexes of 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane with iodine, TCNE and TCNQ

Abstract The charge transfer interaction of the interesting mixed nitrogen–oxygen donor 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8,8,8]hexacosane (HODABCHC) with σ-electron acceptor iodine and π-acceptors tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been investigated spectrophotometrically in chloroform. FT-IR, thermal and elemental analysis measurements are performed for the solid CT-interaction products. The reaction stoichiometries were found to be 1:4, 1:6 and 1:3 donor:acceptor molar ratio for iodine, TCNE and TCNQ reaction systems, respectively. The obtained relatively high reaction stoichiometry values are expected due to the expected high electron donation of the donor (HODABCHC). It contains six oxygen and two nitrogen donor atoms. Accordingly, the formed charge transfer complexes could be formulated as [ ( HODABCHC ) I ] + I 7 - , [(HODABCHC)(TCNE) 6 ] and [(HODABCHC)(TCNQ) 3 ].

Colorimetric sensing of cations and anions by clicked polystyrenes bearing side chain donor–acceptor chromophores

Donor–acceptor chromophores were introduced into the side chains of a polystyrene derivative through the efficient click postfunctional addition reaction between dialkylaniline-activated alkynes and small acceptors, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). The resulting polystyrenes were fully characterized by GPC, 1H NMR, IR spectroscopy, and elemental analysis. After the postfunctionalization, the polymers were highly colored due to the formed donor–acceptor chromophores in the side chains and these chromophores showed a colorimetric sensing behavior for some metal ions and anions. Some hard-to-borderline metal ions were always recognized by the dialkylanilino nitrogen atom, resulting in a decrease in the charge-transfer (CT) band intensity of the donor–acceptor chromophores. However, the recognition site of the soft Ag+ ion was the cyano nitrogen atoms due to readily formed multivalent coordination, leading to a bathochromic shift in the CT bands for both TCNE- and TCNQ-adducted polymers. This remarkable dual colorimetric detection of two different types of metal ions was achieved by the elegant design of polymeric chemosensors. On the other hand, it was found that the dicyanoethene moieties of the side chain chromophores serve as a chemodosimeter for some anions. For example, the CN− ion underwent a nucleophilic addition reaction to the electron-deficient ethene moieties, resulting in a dramatic decrease in the CT bands. All types of sensing behavior of both cations and anions were visually recognized. The use of small molecular model compounds enabled the estimation of the kinetic parameters and the product structures.

ChemInform Abstract: Adapting Semiconducting Polymer Doping Techniques to Create New Types of Click Postfunctionalization

AbstractReview: 77 refs.

Adapting semiconducting polymer doping techniques to create new types of click postfunctionalization

After the historical development from the insoluble polyacetylene film to soluble and processible aromatic polymers, donor-acceptor-type aromatic polymers have recently emerged as a new class of semiconducting polymers. The polymer energy levels and band gaps can be tuned by the appropriate selection of the donor and acceptor moieties, and some of these polymers showed good optoelectronic or photovoltaic performances. The conventional synthetic method for achieving donor-acceptor-type aromatic polymers is based on the metal-catalyzed polycondensation between donor-type monomers and acceptor-type co-monomers. In this tutorial review, a new methodology for introducing donor-acceptor chromophores into semiconducting polymers is described. The donor-acceptor structures are constructed in the main chains and side chains of semiconducting polymers using a polymer reaction based on high-yielding addition reactions between the electron-rich alkynes and strong acceptor molecules, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ). Considering the p-type doping features of TCNE and TCNQ, the experimental procedure is the same as the conventional doping technique for semiconducting polymers. However, the resulting donor-acceptor type polymers are chemically stable due to the absence of unstable unpaired electrons (polarons). The donor-acceptor alternating polymers were achieved in one step from the precursor poly(aryleneethynylene)s and poly(arylenebutadiynylene)s. When the side chain alkynes were post-functionalized, the polymer energy levels were controlled by the species and amount of the employed acceptor molecules. These atom-economic acceptor additions satisfy most of the requirements of the "click chemistry" concept. In contrast to the conventional click chemistry reactions, the reactions between electron-rich alkynes and acceptor molecules provide a wide variety of polymers with promising optoelectronic applications.

Energy level tuning of polythiophene derivative by click chemistry‐type postfunctionalization of side‐chain alkynes

AbstractA polythiophene derivative substituted with electron‐rich alkynes as a side chain was synthesized using the Suzuki polycondensation reaction. The electron‐rich alkynes underwent the “click chemistry”‐type quantitative addition reaction with strong acceptor molecules, such as tetracyanoethylene (TCNE) and 7,7,8,8‐tetracyanoquinodimethane (TCNQ), resulting in the formation of donor–acceptor chromophores. All polymers showed excellent solubilities in the common organic solvents as well as good thermal stabilities with their 5% decomposition temperatures exceeding 230 °C. The TCNE‐/TCNQ‐adducted polymers displayed well‐defined charge‐transfer (CT) bands in the low energy region. The CT energy of the TCNE‐adducted polymer was 2.56 eV (484 nm), which was much greater than that of the TCNQ‐adducted polymer [1.65 eV (750 nm)]. This result was supported by the electrochemical measurements. The electrochemical band gaps of the TCNE‐adducted polymers were much greater than those of the corresponding TCNQ‐adducted polymers. Furthermore, the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels, determined from the first oxidation and first reduction peak potentials, respectively, decreased with the increasing acceptor addition amount. All these results suggested that the energy levels of the polythiophene derivative can be tuned by varying the species and amount of the acceptor molecules using this postfunctionalization method. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010

Double Click Synthesis and Second-Order Nonlinearities of Polystyrenes Bearing Donor−Acceptor Chromophores

Donor−acceptor chromophores were almost quantitatively introduced into the side chains of a polystyrene derivative by sequential “click chemistry”-type addition reactions as an efficient postfunctionalization method. The first click reaction is the conventional Cu(I)-catalyzed azide−alkyne cycloaddition (CuAAC), and the second one is the atom-economic addition of strong acceptor molecules, such as tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ), to the aniline-substituted electron-rich alkynes. Steric hindrance was found to be an important factor in determining the reactivity of alkyne-acceptor addition reactions. All obtained polymers showed good solubility in common organic solvents, and they were fully characterized by GPC, 1H NMR and IR spectroscopy, and elemental analysis. After the acceptor addition, the polymers showed an intense charge-transfer (CT) band centered at ca. 480 nm for the TCNE adducts and ca. 710 nm for the TCNQ adducts. Electrochemical measurements of these poly...

Utility of Ion-Pair and Charge Transfer Complexation for Spectrophotometric Determination of Domperidone and Doxycycline in Bulk and Pharmaceutical Formulations

Four simple, sensitive, and accurate spectrophotometric methods (A-D) have been developed for the determination of domperidone (I) and doxycycline (II) in bulk and in pharmaceutical formulations. The first two methods (A and B) are based on the formation of yellow ion-pair complexes between the examined drugs with bromocresol green (BCG) and methyl orange (MO) as chromophoric reagents in Britton-Robinson (B-R) universal buffer of pH 3.0 and 2.2, respectively. The formed complexes were extracted with chloroform and measured at 420 nm and 424 nm for I and II using BCG, respectively and 480 nm for the studied drugs using MO. The last two methods (C and D) are based on charge transfer complex formation between the studied drugs and tetracyanoethylene (TCNE); and 7,7,8,8-tetracyanoquinodimethane (TCNQ). Different variables affecting the reactions were studied and optimized. Under the optimum reaction conditions, linear relationships with good correlation coefficients (0.9992 - 0.9998) were found between the absorbance and the concentration of I in the range of 1.4-22.4μg mL −1 , whereas that for II in the range 1.4-25.5μg mL −1 . For more accurate analysis, Ringbom optimum concentration range was found to be between 3.0-21.5 and 3.0-23.5μg mL −1 , for I, and II, respectively. Sandell’s sensitivity, correlation coefficient, and limits of detection and quantification were calculated for each method. A Job’s plot of the absorbance versus the molar ratio of drug to each of formed complex under consideration indicated (1:1) ratio. No interference was observed from common pharmaceutical excipients and additives. Statistical comparison of the results with those obtained by the official method shows excellent agreement and indicates no significant difference in accuracy and precision.

Synthesis, spectroscopic and thermal investigations of solid charge-transfer complexes of 1,4,7-trimethyl-1,4,7-triazacyclononane and the acceptors iodine, TCNE, TCNQ and chloranil

The solid charge-transfer complexes formed in the reaction of the electron donor 1,4,7-trimethyl-1,4,7-triazacyclononane (TMTACN) with the acceptors iodine, tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) have been isolated. These were characterized through electronic and infrared spectra as well as thermal and elemental analysis. The results show that the formed solid CT-complexes have the formulas [(TMTACN)I]I 3, [(TMTACN)(TCNE) 5] and [(TMTACN)(TCNQ) 3] in full agreement with the known reaction stoichiometries in solution. The chloranil CT-solid complex cannot be isolated in pure form.

Synthesis and characterization of novel charge transfer complexes formed by N, N′-bis(ferrocenylmethylidene)- p-phenylenediamine and N-(ferrocenylmethylidene)aniline

N, N′-Bis(ferrocenylmethylidene)- p-phenylenediamine 1 and N-(ferrocenylmethylidene) aniline 2 are readily synthesized by Schiff base condensation of appropriate units. Iodine (I 2), 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), tetrachloro-1,4-benzoquinone (CA), tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) form charge transfer complexes with 1 and 2. IR spectroscopy suggests an increase in the amount of charge transferred from the ferrocenyl ring to the oxidant in the order, I 2<CA<TCNQ<TCNE≈DDQ. EPR spectra of the oxidized binuclear complexes are indicative of localized species containing iron- and carbon-centered radicals. The Mössbauer spectrum of the iodine oxidized complex of 1 reveals the presence of both Fe(III) and Fe(II) centers. Variable temperature magnetic and Mössbauer studies show that the ratio of Fe(III)/Fe(II) centers varies as a function of temperature. The larger Fe(II)/Fe(III) ratio at lower temperatures is best explained by a retro charge transfer from the iodide to the iron(III) metal center. There is negligible solvent effect on the formation of the iodine oxidized charge transfer complex of 1.

Insertion of Electron-Deficient Olefins into the C–H Bond of 2-Furanyl- and 2-Thienylplatinum Complexes

Abstract The treatment of 2-furanylplatinum with maleic anhydride (MA), tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) results in insertion of the olefins into the C–H bond of furanyl group at the 5-position. 2-Thienylplatinum complex similarly reacts with TCNE and TCNQ to give the insertion products.

The oxidation of distannanes by the tetracyanoethylene and 7,7,8,8-tetracyanoquinodimethane

The reaction of tetracyanoethylene (TCNE) and 7,7,8,8-tetracyanoquinodimethane (TCNQ) with distannanes result in the formation of complexes of the types R 3Sn(TCNE) and R 3Sn(TCNQ) (R = Me, Bu). Hexaphenylditin and TCNQ give the complex (Ph 3Sn) 2 · (TCNQ).