A STUDY OF THE SUBSTITUTION OF SOME FLUOROAROMATICS USING (PB(SPH)3)-, (PB(SEPH)3)- AS A SOURCE OF THE EPH- NUCLEOPHILE

A pb-207 NMR study of Pb (SPh)2/DMF mixtures, which are known to act as a source of the SPh- nucleophile, suggests that they contain species with the Pb(II)S3 kernel. To discover whether the carrier of SPh- could be [Pb(SPh)3]-, the room-temperature reactions of (AsPh4) [Pb(SPh)3] (1) with the representative substrates (C6F5)2, 2,4-C6H3 (NO2)2F and C6F6 in CHCl3 (or CDCl3/CHCl3) have been investigated. The known compounds 4,4'- (C6F4 (SPh))2 and 2,4-C6H3 (NO2)2 (SPh) are formed readily from the first and second substrates, but the conversion of C6F6 to 4-C6F4 (SPh)2 is very slow under the conditions used. Enroute to 4,4'-(C6F4 {SPh})2, the new compound 4-C6F5.C6F4 (SPh) is formed. For (C6F5)2 and 2,4-C6H3(NO2)2F, analogous but slower reactions are observed using (AsPh4) [Pb(SePh)3] (2), as a source of SePh-, but no reaction of C6F6 with 2 was observed. In general, reactions of 2 are complicated by its ease of oxidation to Ph2Se2.