Tricyanovinylalkynyl-metal complexes: synthesis and some reactions.

Reactions of Group 8 metal ethynyls with tetracyanoethene afford tricyanovinylethynyl-metal derivatives, M{C[triple bond]CC(CN)=C(CN)(2)}(PP)Cp' [2; M = Ru, Os; PP = (PPh(3))(2), dppe; Cp' = Cp, Cp*; not all combinations]; a similar reaction occurs with the vinylidene RuCl(=C=CHPh)(PPh(3))Cp. Further replacement of a CN group in occurs with nucleophiles, while homo- and hetero-metallic derivatives are obtained by coordination of one of the remaining CN groups to other metal-ligand fragments.

Syntheses, structures and redox properties of some complexes containing the Os(dppe)Cp* fragment, including [{Os(dppe)Cp*}2(mu-C triple bondCC triple bond C)].

The sequential conversion of [OsBr(cod)Cp*] (9) to [OsBr(dppe)Cp*] (10), [Os([=C=CH2)(dppe)Cp*]PF6 ([11]PF6), [Os(C triple bond CH)(dppe)Cp*] (12), [{Os(dppe)Cp*}2{mu-(=C=CH-CH=C=)}][PF6]2 ([13](PF6)2) and finally [{Os(dppe)Cp*}(2)(mu-C triple bond CC triple bond C)] (14) has been used to make the third member of the triad [{M(dppe)Cp*}2(mu-C triple bond CC triple bond C)] (M = Fe, Ru, Os). The molecular structures of []PF6, 12 and 14, together with those of the related osmium complexes [Os(NCMe)(dppe)Cp*]PF6 ([15]PF6) and [Os(C triple bond CPh)(dppe)Cp*] (16), have been determined by single-crystal X-ray diffraction studies. Comparison of the redox properties of 14 with those of its iron and ruthenium congeners shows that the first oxidation potential E1 varies as: Fe approximately Os < Ru.