Polynuclear carbon-rich organometallic complexes: clarification of the role of the bridging ligand in the redox properties

Ferrocene‐ and Biferrocene‐Containing Macrocycles towards Single‐Molecule Electronics

“…Communication between redox‐active centers is highly studied, with the identification of useful bridging ligands, binding groups, and suitable redox‐active components, furthermore establishing a solid understanding in redox center communication and electronic coupling in mixed valence states 9, 10, 11. Multiple redox‐active groups within molecular wires show interesting results in conductance modulation 12, 13, 14.…”

Some Ruthenium Derivatives of Penta-1,4-diyn-3-one

“…The significant weighting of the carbon-rich fragment in the HOMO is common in ruthenium complexes of this type. 15,44,49,50 There is a re-ordering of the HOMO-1 and HOMO-2 orbitals relative to those of the computational model system {trans-Fe(Me)(dHpe) 2 } 2 (-DEE) studied by Cao and Ren, 26b but neither of these orbitals feature any appreciable contribution from the ethenyl -system. The ligand * system lies well above the unoccupied orbitals of the Ru(dppe)Cp* fragments and comprises the LUMO+18.…”

“…Consequently, this family of compounds can be used to construct compounds which display: metal-localised redox character, giving rise to well- Complex 2 and its derivatives provide a useful opportunity to extend these studies to include an assessment of the influence of a cross-conjugated carbon-rich ligand on the electrochemical response (Table 2) and electronic nature of the complexes and redoxrelated products, complementing recent investigations with complexes featuring gemenediyne and linear polyynediyl based bridging ligands. 11,15,26 The closely related complexes 2 and 7 each undergo three sequential one-electron oxidations at moderate potentials, the third being irreversible in each case. The substantial separation of the first two redox processes E 1/2 (2) -E 1/2 (1) = 200 mV (2), 300 mV (7) gives rise to large comproportionation constants K C , indicating the significant thermodynamic stability of the electrochemically generated monocations estimated from peak potentials of an only partially chemically reversible process.…”

“…There is much current interest in the electronic structures of these complexes, and both experimental and computational results suggest that the inserted group may act as an insulator or an amplifier, with respect to the extent of -conjugation between the metal end-groups. 7-9,13, [15][16][17][18][19] We and others have also studied the effect of inserting a variety of organic groups, 15 particularly aromatic hydrocarbon and heterocyclic systems, into the carbon chain of complexes {L n M}(C≡C) x {ML n }, on the electronic interactions between the endgroups. [20][21][22][23][24][25] The metal end-groups are often strongly electron-donating in character, such as M(dppe)Cp* (M = Fe, Ru) and the formal insertion of electron-attracting groups, such as CO, C=CH 2 , C=C(CN) 2 , into the bridge is a natural extension of this work, whilst also allowing further exploration of bimetallic complexes featuring cross-conjugated, carbon-rich ligands.…”

Synthesis, Structure and Electrochemical Properties of Triarylamine Bridged Dicobaltdicarbon Tetrahedrane Clusters

“…These systems are ideal candidates for the study of intramolecular electron transfer processes [5][6][7], which in turn underpin applications in catalysis [8], energy science [9, 10] and molecular electronics [11,12] whilst also illustrating fine details of electronic structure arising from the often unexpected redox activity of the supporting or bridging ligands [13][14][15][16][17]. Whilst the considerable majority of studies in this area have focussed on bis(monometallic) complexes in which two metal centres are linked through a (usually -conjugated) bridging ligand [18,19], systems derived from organic electrophores [20] and cluster systems [21] have not been overlooked.…”