The racemic methyl complexes (η 5 -C 5 Me 5 )Re(NO)(PR 3 )(CH 3 ) (R: b, 4-C 6 H 4 CH 3 ; c, 4-C 6 H 4t-C 4 H 9 ; d, 4-C 6 H 4 C 6 H 5 ; e, c-C 6 H 11 ), which feature phosphines that are more electron rich and/or bulkier than P(C 6 H 5 ) 3 , are elaborated by reactions with HBF 4 ‚OEt 2 /chlorobenzene, HCtCH or HCtCCtCSiMe 3 , and t-BuOK to give the alkynyl complexes (η 5 -C 5 Me 5 )Re(NO)-(PR 3 )(CtCH) (3b,c) and (η 5 -C 5 Me 5 )Re(NO)(PR 3 )(CtCCtCSiMe 3 ) (7b-e). The latter are converted (K 2 CO 3 /MeOH or wet n-Bu 4 N + F -) to butadiynyl complexes (8b-e). Homo-or crosscouplings (3b, 8b-e; Cu(OAc) 2 /pyridine) lead to the µ-butadiynediyl complex (η 5 -C 5 Me 5 )Re-(NO)(PR 3 )(CtC) n (R 3 P)(ON)Re(η 5 -C 5 Me 5 ) (4b; n ) 2) and analogous µ-hexatriynediyl (10b; n ) 3) and µ-octatetraynediyl (9b-e; n ) 4) species. Oxidation of 4b by AgSbF 6 (ca. 1:1 or 1:2) gives the radical cation 4b •+ SbF 6or the dication 4b 2+ (SbF 6 -) 2 . These isolable compounds exhibit delocalized mixed-valence and cumulenic electronic ground states, respectively. The cyclic voltammograms of 9b-e and 10b show oxidations to analogous species, with much better chemical reversibilities than for the P(C 6 H 5 ) 3 analogues. However, these longer chain systems decompose rapidly at -78 °C and could not be isolated or spectroscopically characterized.
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