Incorporation of stable organic radicals of the tris(2,4,6-trichlorophenyl)methyl radical series to pyrrole units as models for semiconducting polymers with high spin multiplicity.: 1.: [2,6-dichloro-4-[2,5-bis(5-methyl-2-thienyl)-1-pyrrolyl]phenyl]bis(2,4,6-trichlorophenyl)methyl radical as a precursor of a disjoint heterospin diradical with a triplet or a nearly degenerate singlet-triplet ground state

The condensation re actions between (4-amino-2,6-dichlorophenyl)bis(2,4,6-trichlorophenyl)methyl radical and acetylacetone or 1,4-bis(5-methyl-2-thienyl)-1,4-butanedione yield [2,6-dichloro-4-(2,5-dimethyl-1-pyrrolyl)phenyl]bis(2,4,6-trichlorophenyl)methyl radical (3(.)) and [2,6-dichloro-4-[2,5-bis(5-methyl-2-thienyl)-1-pyrrolyl]phenyl]bis(2,4,6-trichlorophenyl)methyl radical (4(.)), respectively. EPR studies of both radicals;. and 4 in CH2Cl2 solution suggest a weak electron delocalization with coupling constant values of 1.25 and 1.30 G, respectively, with the six aromatic hydrogens. Their electrochemical behavior was analyzed by cyclic voltammetry. Both radicals show reversible reduction processes at E-o = -0.69 V and -0.61 V versus SSCE, respectively, and anodic peak potentials at E-p(a) = 1.10 and 0.72 V, respectively, versus SSCE at a scan late (nu) of 200 mV s(-1) being reversible for radical 4(.). X-ray analysis of radical 3(.) shows a high value (65 degrees) of the dihedral angle between the 2,5-dimethylpyrrolidyl moiety and the phenyl ring. Smooth oxidation of radical 4. in CH2Cl2 containing trifluoroacetic acid gives an ionic diradical species with a weak electron interaction (\D/hc\ = 0.0047 cm(-1)). A Curie plot of the Deltam(s) = +/-2 signal intensity versus the inverse of the absolute temperature in the range between 4 and 70 K suggests a triplet or a nearly degenerate singlet-triplet ground state.