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

Five-Membered Heterocycles as Linking Units in Strongly Coupled Homobimetallic Group 8 Metal Half-Sandwich Complexes

“…This results in a somewhat C-shaped bending for 11a and 12a and an S-shape for 12b (Figure SI1). The rotation of the C 5 H 5 ring of the (η 5 -C 5 H 5 )(P 2 )MCC fragments (M = Fe, Ru; P 2 see Table SI1) toward each other reveals an anti-arrangement for 11a and 12a,b, which is in accordance with the only literature-reported example for M = Fe, 37 whereas for M = Ru also deviating conformations are reported (Table SI1). 36,37,66−73 Electrochemistry.…”

“…The investigation of organometallic compounds bearing π-conjugated organic bridging ligands between transition metal atoms has increased significantly during the last 30 years. − In particular, alkynyl transition metal complexes are well studied, due to their high stability, π-conjugation, and rigid structure. They are well suited, for example, as models for “molecular wires” − and for the construction of nanoscale electronic devices. − Besides σ-complexes with end-on bonded alkynes, tweezer-type complexes with both σ- and π-coordination have been investigated, as they allow cooperative and synergistic effects between the metal centers. − Examples of alkynyl transition metal complexes are given by the works of, for example, Lapinte, − Low, − and Bruce. , Besides bridges solely built of alkyne chains, − other organic linkers such as benzene, ,,, naphthalene, , anthracene, ,, bipyridine, 1,12-carbaborane, cyanoacetylide, dithia[3.3]­paracyclophane, and biferrocene ,− have been introduced in alkyne-based “all-carbon” units. Hence, the influence of the chain length and the nature of the organic unit on the intramolecular electronic communication between the transition metals in homo- and heterobimetallic compounds were investigated.…”

1,1′‐Diaryl‐Substituted Ferrocenes: Up to Three Hinges in Oligophenyleneethynylene‐Type Molecular Wires

“…[9][10][11][12][13] A precondition for this development is the possibility of electron-transfer through the ferrocene unit along a molecular wire. Such conductivity has recently been established by Engtrakul and Sita [12,13] as well as by Dong and coworkers [14,15] and is presumably a result of the redox activity of ferrocene. [16] The ferrocene subunits render the wire three-dimensional and thereby make π-π stacking less likely.…”

Synthesis, Spectroelectrochemical, and EPR Spectroscopic Studies of Mixed Bis(alkynyl)biferrocenes of the Type (LnMC≡C)(LnM′C≡C)bfc

“…The frequencies are very close to those found for mono-and dinuclear compounds of the (Cp*)(η 2 -dppe)Fe−CCR and (Cp)(PPh 3 ) 2 M−CCR (M = Ru, Os) type. 28,49,50,55,56 It was of interest to explore the nature of the interactions occurring between the different metal termini via the bfc connectivity as oxidation processes occurred. The IR spectra of the chemically stable oxidized species 5a−c[PF 6 ] n (n = 1, 2) were obtained using the spectroelectrochemical method in an OTTLE (optical transparent thin layer electrode) cell at ambient temperature.…”

“…28 It is also known that biferrocene-1′,1‴-diynes can act as linking groups for diverse organometallic termini, conveying intramolecular electronic interaction from one end to the other, whereby the strongest interaction occurs between the terminal metal center and the bfc unit. 28,32,33 This prompted us to synthesize and study the electrochemical and spectroelectrochemical properties of mixed-transition-metal complexes featuring the bis(CC)biferrocenyl moiety as a connecting unit between redox-active termini, since only little is known about this family of compounds. 1,2,30 One example is (Cp*)(η 2 -dppe)Fe−CC− bfc−CC−Fe(η 2 -dppe)Cp* (3a), showing that the mixedvalent species is in alignment with a class II molecule in the classification scheme of Robin and Day with an electron transfer involving intermediate states.…”