Synthesis, Spectroscopy and Electrochemistry in Relation to DFT Computed Energies of Ferrocene- and Ruthenocene-Containing β-Diketonato Iridium(III) Heteroleptic Complexes. Structure of [(2-Pyridylphenyl)2Ir(RcCOCHCOCH3]

Abstract

A series of new ferrocene- and ruthenocene-containing iridium(III) heteroleptic complexes of the type [(ppy)2Ir(RCOCHCOR′)], with ppy = 2-pyridylphenyl, R = Fc = FeII(η5-C5H4)(η5-C5H5) and R′ = CH3 (1) or Fc (2), as well as R = Rc = RuII(η5-C5H4)(η5-C5H5) and R′ = CH3 (3), Rc (4) or Fc (5) was synthesized via the reaction of appropriate metallocene-containing β-diketonato ligands with [(ppy)2(μ-Cl)Ir]2. The single crystal structure of 3 (monoclinic, P21/n, Z = 4) is described. Complexes 1–5 absorb light strongly in the region 280−480 nm the metallocenyl β-diketonato substituents quench phosphorescence in 1–5. Cyclic and square wave voltammetric studies in CH2Cl2/[N(nBu)4][B(C6F5)4] allowed observation of a reversible IrIII/IV redox couple as well as well-resolved ferrocenyl (Fc) and ruthenocenyl (Rc) one-electron transfer steps in 1−5. The sequence of redox events is in the order Fc oxidation, then IrIII oxidation and finally ruthenocene oxidation, all in one-electron transfer steps. Generation of IrIV quenched phosphorescence in 6, [(ppy)2Ir(H3CCOCHCOCH3)]. This study made it possible to predict the IrIII/IV formal reduction potential from Gordy scale group electronegativities, χR and/or ΣχR′ of β-diketonato pendent side groups as well as from DFT-calculated energies of the highest occupied molecular orbital of the species involved in the IrIII/IV oxidation at a 98% accuracy level.

Redox and Photophysical Properties of Four Subphthalocyanines Containing Ferrocenylcarboxylic Acid as Axial Ligands

“…Both HOMO and HOMO–1 were located on the iron center; however, experimentally it was found that the second oxidation of SubPcs 5 – 8 was assigned to be SubPc ring-based instead. Since it sometimes happens that orbitals can rearrange upon oxidation, − it therefore is essential to optimize the cation (oxidized) species as well, in order to computaionally locate the locus of the second experimentally observed oxidation. The oxidized SubPcs 5 – 8 all showed that their LUMO is on the iron center (first oxidation) and the HOMO and HOMO–1 of the oxidized species both are on the SubPc-ring (second and third oxidation), in agreement with the experimental assignment; see Figure .…”

Cyclic Voltammetric and DFT Analysis of the Reduction of Manganese(III) Complexes with 2‐Hydroxybenzophenones

“…Upon reduction of mer molecule 1, an electron is added to the LUMO of complex 1, which is of character (Figure 3). This LUMO then becomes the HOMO of the reduced molecule 1, if no re‐arrangement of the frontier orbitals occurs during reduction [31–33]. This new HOMO of the reduced mer complex 1, also shown in Figure 3, now has character, while the new LUMO of reduced complex 1, as well as LUMO+1 to LUMO+10, is ligand based.…”

“…This was nicely illustrated by the occupied molecular orbital of (Figure 3). This LUMO then becomes the HOMO of the [31][32][33]. This new HOMO of the reduced mer complex 1, also shown in Figure 3, now has d x 2 À y 2 character, while the new LUMO of reduced complex 1, as well as LUMO + 1 to LUMO + 10, is ligand based.…”

Synthesis, Electrochemistry, XPS, and DFT Calculations of α-Carbon-Bonded Gold(I) Ferrocenyl- and Ruthenocenyl-Containing β-Diketonato Complexes

“…The higher-energy absorption bands below 300 nm are assigned to spin-allowed intraligand π–π* transitions (corresponding to ligand-centered states, 1 LC), while the lower-energy absorption bands between 300 and 540 nm are assigned to a mixture of metal-to-ligand charge transfers ( 1 MLCT and 3 MLCT). , Subsequently, absorption bands in the region 460–510 nm can be ascribed to the ferrocenyl moiety of complexes 2–5 and 10 . Absorption trends by these complexes deviated from the Beer–Lambert law, A = ε Cl , at concentrations greater than 30–40 μM, and may be the consequence of the onset of intermolecular associations.…”