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-metlhyl-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-t richlorophenyl)methyl radical and acetylacetone or 1,4-bis(5-methyl-2-thien yl)-1,4-butanedione yield [2,6-dichloro-4-(2,5-dimethyl-1-pyrrolyl)phenyl]b is(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 rad ical (4(.)), respectively. EPR studies of both radicals;. and 4 in CH2Cl2 s olution suggest a weak electron delocalization with coupling constant value s 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 SSC E, respectively, and anodic peak potentials at E-p(a) = 1.10 and 0.72 V, re spectively, versus SSCE at a scan late (nu) of 200 mV s(-1) being reversibl e for radical 4(.). X-ray analysis of radical 3(.) shows a high value (65 d egrees) of the dihedral angle between the 2,5-dimethylpyrrolidyl moiety and the phenyl ring. Smooth oxidation of radical 4. in CH2Cl2 containing trifl uoroacetic acid gives an ionic diradical species with a weak electron inter action (\D/hc\ = 0.0047 cm(-1)). A Curie plot of the Deltam(s) = +/-2 signa l intensity versus the inverse of the absolute temperature in the range bet ween 4 and 70 K suggests a triplet or a nearly degenerate singlet-triplet g round state.