Pyridinediimine Iron Complexes with Pendant Redox-Inactive Metals Located in the Secondary Coordination Sphere

Abstract

A series of pyridinediimine (PDI) iron complexes that contain a pendant 15-crown-5 located in the secondary coordination sphere were synthesized and characterized. The complex Fe((15c5)PDI)(CO)2 (2) was shown in both the solid state and solution to encapsulate redox-inactive metal ions. Modest shifts in the reduction potential of the metal-ligand scaffold were observed upon encapsulation of either Na(+) or Li(+).

Uncoupled Redox-Inactive Lewis Acids in the Secondary Coordination Sphere Entice Ligand-Based Nitrite Reduction

“…As stated above, Fe(PDI)(CO) 2 complexes are well-known to display a one-electron oxidation ( E OX ) to form [Fe(PDI)-(CO) 2 ] + and a reversible (or quasi-reversible) one-electron reduction ( E RED ) to form [Fe(PDI)(CO) 2 ] − (eq 1). Because of the documented solvent dependence on the different events, 73 the E OX values were obtained in DCM and the E RED values were obtained in CH 3 CN. In DCM (vs Fc +/0 ), upon Na + encapsulation, 84 the E OX event shifts 31 mV (from −0.523 V in 2 to −0.492 V in 3 ; see Figure 8).…”

Ligand-based reduction of nitrate to nitric oxide utilizing a proton-responsive secondary coordination sphere

“…Ion chromatography was performed on a Dionex model 201 DI High Performance Ion Chromatograph (HIPC) with a simple anion column and a conductivity detector. The complex [Fe(Hdidpa)(CO)2] + (2) was synthesized according to literature procedures [3].…”

“…Data for C29H44F6FeN6O2P (M =709.52 g/mol) (3): triclinic, space group P-1 (no. 2), a = 8.3541(4) Å, b = 12.2825(6) Å, c = 16.8758(6) Å, α = 80.311(4)°, β = 85.323(3)°, γ = 78.583(4)°, V =1671.05(13) Å3 , Z = 2, T = 100(2) K, μ(MoKα) = 0.569 mm-1 , Dcalc = 1.410 g/cm3 , 27521 reflections measured (4.512° ≤ 2Θ ≤ 54.966°), 7556 unique (Rint = 0.0271, Rsigma = 0.0236) which were used in all calculations. The final R1 was 0.0266 (I > 2σ(I)) and wR2 was 0.0718 (all data).Mössbauer Spectra.…”

Use of Crown Ether Functions as Secondary Coordination Spheres for the Manipulation of Ligand–Metal Intramolecular Electron Transfer in Copper–Guanidine Complexes

“…Herein we report on copper complexes with a redox‐active bisguanidine ligand with attached crown ether function, allowing to control the electronic structure of the metal complexes by encapsulation of a metal. Crown ether functions were used in the past to vary the redox potential of transition metal complexes, for example, of ferrocene, [37] cobalt Schiff base complexes, [38] or iron complexes of pyridine‐diimines [39, 40] . The example in Figure 2 a shows a ferrocene with a crown ether group attached to one of the cyclopentadienyl rings [36] .…”