Syntheses, Structures, Some Reactions, and Electrochemical Oxidation of Ferrocenylethynyl Complexes of Iron, Ruthenium, and Osmium

Abstract

The syntheses and characterizations of several complexes containing ferrocenylethynyl and ferrocene-1,1‘-bis(ethynyl) groups attached to M(PP)Cp‘ [M = Fe, Ru, PP = dppe, Cp‘ = Cp*; M = Ru, Os, PP = (PPh3)2, dppe, Cp‘ = Cp] are described. Reactions with tetracyanoethene have given either tetracyanobuta-1,3-dienyl or η3-allylic derivatives, while addition of Me+ afforded the corresponding vinylidene derivatives. Some electrochemical measurements are discussed in terms of electronic communication between the redox-active M(PP)Cp‘ groups through the ferrocene nucleus. The molecular structures of 14 of these complexes have been determined by crystallographic methods.

Ligand Redox Non‐Innocence in Transition‐Metal σ‐Alkynyl and Related Complexes

“…Chemical oxidation of the dppe-ligated congeners of these two complexes yielded only unstable, impure mixtures of oxidised material, [187] although low-temperature spectroelectrochemical experiments were able to satisfactorily characterise the oxidation products to be consistent with the above descriptions. [188] The underlying causes of the relative instability of the dppe-ligated complexes were not readily apparent from the experimental data, although the source of the difference is presumably electronic in nature.…”

“…In the most fundamental illustration of this premise one may consider the complex [Ru(CϵCFc)(PPh 3 ) 2 Cp] ·+ (Scheme 26). [187,188] Whereas the phenylethynylene complex [Ru(CϵCPh)(PPh 3 ) 2 …”

Heterometallic complexes containing 1,1′-(CC)2Fc′ units linking two different metal centres

“…Precursor 1 (Scheme 1) was prepared in 46% yield as described earlier [9], from 1,1 0 -(Me 3 SiC"C) 2 Fc 0 and one equivalent of RuCl(dppe)Cp * in the presence of KF. Treatment of 1 with [NBu 4 ]F in thf containing a small amount of water resulted in ready proto-desilylation and formation of orange 1-(HC"C)-1 0 -{Cp * (dppe)RuC"C}Fc 0 (2).…”

“…This complex contained strong m(C"C) bands at 2100, 2074 and 2057 cm À1 (cf. 2107, 2082 cm À1 for the Ru 2 analogue [9]) and resonances in the 1 H NMR spectrum at d 1.56 and 1.69, assigned by comparison with 7 to the Fe-and Ru-bonded Cp * Me Table 1 Selected bond distances (Å ) and angles (°)…”

“…Recently, we have reported several complexes containing Ru(PP)Cp 0 groups end-capping the 1,1 0 -Fc 0 (C"C-) 2 nucleus [9]. Similar ruthenocene complexes, and compounds of the type Ru{(C"C) n Fc}(PP)Cp 0 [PP = (PPh 3 ) 2 , dppm, dppe, dppf; Cp 0 = Cp, Cp * ] (n = 1, 2, 3) have also been made [10].…”