Synthetic and electrochemical studies on alkynyl complexes of iron and ruthenium

Synthesis and structure of the diynyl complexes [Mo(CCCCR)L2(η-C7H7)], L2=chelate N- or P-donor ligand, R=SiMe3 or H: X-ray crystal structures of [Mo(CCCCSiMe3)(2,2′-bipyridine)(η-C7H7)] and [Mo(CCCCH)(Ph2PCH2CH2PPh2)(η-C7H7)]

“…Two points emerge which suggest that synthetic redox studies on butadiynyl complexes of the MoL 2 (g-C 7 H 7 ) system will lead to unprecedented isolation of metal-stabilised butadiynyl radicals [30,31]. First, the E°values for the Mo(g-C 7 H 7 ) complexes are to negative potential of both RuCp * and FeCp * analogues in accord with previous measurements on the related alkynyl derivatives [M(C" CPh)(dppe)(g-L)] (M = Mo, L = C 7 H 7 ; M = Fe or Ru, L = Cp * ) [32]. Second, the chemical reversibility of the one-electron oxidation processes is enhanced by the Mo(dppe)(g-C 7 H 7 ) auxiliary such that not only does the C 4 SiMe 3 derivative 4 exhibit a fully reversible one-electron oxidation but also, exceptionally, so does the unprotected C 4 H derivative 6; moreover the same observation is made for the Bu t -dab derivatives 2 and 5.…”

Long-distance electronic interaction in a molecular wire consisting of a ferrocenyl–ethynyl unit bridging two [(η5-C5H5)(dppe)M] metal centers

“…3, the redox behavior in 1 and 2 is dominated by the two reversible Ru 2+ / Ru 3+ redox couples (E 1/2 at 0.05 and 0.57 V in 1; 0.10 and 0.27 V in 2) and reversible ferrocene-based Fe 2+ /Fe 3+ redox couples (E 1/2 at 0.86 V in 1; 0.73 and 0.87 V in 2) vs. Ag/AgCl. For complex 3, one reversible Ru 2+ /Ru 3+ redox couple (E 1/2 at 0.14 V) and three (7); Fe1-C2, 2.026(7); Fe1-C3, 2.027(6); Fe1-C4, 2.048(7); Fe1-C5, 2.037(7); Fe1-C6, 2.072(7); Fe1-C7, 2.035(6); Fe1-C8, 2.033(6); Fe1-C9, 2.026(7); Fe1-C10, 2.041(7); Fe2-C11, 2.093(7); Fe2-C12, 2.085(7); Fe2-C13, 2.075(7); Fe2-C14, 2.077(7); Fe2-C15, 2.087(7); Fe2-C17, 1.883 (9) Quasi-reversible and irreversible waves were observed in the CV measurements of complexes 1 [20], [(g 5 -C 5 H 5 )(PPh 3 ) 2 Ru-C"C-Ph] [35], [(g 5 -C 5 H 5 )(PPh 3 ) 2 Ru-C"C-fc] (fc = ferrocenyl) [30], and [(g 5 -C 5 H 5 )(dppe)Ru-C"C-fc]. Therefore, differential pulse voltammetry was employed to obtain better-resolved potential information in our study, because the Fe 2+ /Fe 3+ redox process for 2 and 3 was quasi-reversible in the CV experiment.…”

Spectroscopic properties and electronic structures of 17-electron half-sandwich ruthenium acetylide complexes, [Ru(CCAr)(L2)Cp′]+ (Ar=phenyl, p-tolyl, 1-naphthyl, 9-anthryl; L2=(PPh3)2, Cp′=Cp; L2=dppe; Cp′=Cp∗)

“…No special precautions were taken to exclude air or moisture during work-up. The compounds [RuCl(PPh 3 )Cp] [36], [RuCl(dppe)Cp * ] [37], [Ru(C"CPh)(PPh 3 )Cp] [38], [Ru(C"CC 6 H 4 -Me-4)(dppe)Cp * ] [39], Ru(C"CPh)(dppe)Cp * [20] and 1-trimethylsilylethynylanthracene (purified by column chromatography on silica gel, eluting with hexane) [40], were prepared by the literature methods. Other reagents, including 4-ethynylnaphthalene (Aldrich) and 4-ethynyltoluene (Aldrich) were purchased and used as received.…”