Novel electron acceptors bearing a heteroquinonoid system, 5,5′-bis(dicyanomethylene)-5,5′-dihydro-Δ2,2′-bithiophene, its 3,3′-dichloro, 3,3′-dibromo, and 3,3′,4,4′-tetrabromo derivatives, and 5,5″-bis(dicyanomethylene)5,5″-dihydro-Δ2,2′:5′,2″-terthiophene were synthesized by the action of tetracyanoethylene oxide or by Pd(0)-catalyzed substitution reactions with sodium dicyanomethanide on the corresponding α,α′-dihalogenoheteroaromatics. They showed very small on-site Coulomb repulsion as expected, and afforded several highly conductive molecular complexes with electron donors such as hexamethylenetetratellurafulvalene.

Conjugated dimeric TTFs linked with an ethenylene or ethynylene spacer were prepared as novel electron donors and preferentially formed 1:1 complexes with TCNQF4 and with DDQ, which were more conductive than those of monomeric TTFs.

2,3 : 6,7-Dibenzobicyclo[3.3.1]nona-2,6-diene-4,8-diol was synthesized and resolved via (−)-menthoxyacetate. Several kinds of optically active derivatives with the same absolute configuration were prepared from the (−)-diol and their chiroptical properties were recorded. The absolute configuration of this series of compounds was determined to be 1R, 5R by a chemical correlation with (R)-(−)-3-phenylbutanoic acid via (−)-1,3-diphenylglutaric acid and (−)-2,4-diphenylpentane.

Pyrolyses of a series of selenides and diselenides were studied. Selenides and diselenides bound with an active methylene group like benzyl gave a variety of substituted bibenzyls and related ethane derivatives in high yields. Other diselenides were easily caused to cleave to give various aromatic and aliphatic olefins in good yields together with elemental selenium. Lepidopterene, [2.2]paracyclophane, and benzocyclobutene were prepared by thermal cleavage of their corresponding phenylselenomethyl-substituted compounds as an application of the pyrolysis concerned.

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Two conjugated homologues of thiophene-7,7,8,8-tetracyanoquinodimethane (TCNQ) have been prepared, which form highly conductive complexes with typical electron donors such as 2,2',5,5'-tetrathiafulvalene (TTF) or 5,6,11 ,I 2-tetrathiatetracene (TTT); these complexes have extensive conjugation.-t New compounds (3) and (4) were characterized by elemental and spectrocopic analyses.$ All complexes except non-stoicheiomeric (3) .TTF consist of 1 : 1 donor and acceptor components.

Various radical cation salts of 2,3-dimethyl-tetrathioanthracene (DMTTA) and -tetraselenoanthracene (DMTSA) with NO3−, BF4−, ClO4−, PF6−, AsF6−, and Br− counter anions were prepared by an electrocrystallization technique. It has been found that these salts have either 1 : 1 or 2 : 1 stoichiometry depending on the volumes of the anions, but all are electrically conductive regardless of the stoichiometries. In particular, the NO3 and BF4 salts of DMTSA, in spite of 1 : 1 stoichiometry, recorded unusually high room temperature conductivities of 440 and 450 S cm−1, respectively, and had metallic behaviors down to around 200 K. In addition, the other salts were semiconductors with very low activation energies. X-Ray crystallographic analyses showed that the crystal structures of all the salts consist of one-dimensional stacking columns of the donor molecules, but the two metallic salts have more favorable uniform stacking columns in which there are not only effective π electronic interactions but also strong heteroatomic interactions. Furthermore, solid electronic spectra indicated that these 1 : 1 radical cation salts have the advantage of marked reduction of on-site Coulombic repulsion in the donor molecules, which serves to suppress a Mott transition.