Tuning the Oxidation Level, the Spin State, and the Degree of Electron Delocalization in Homo- and Heteroleptic Bis(α-diimine)iron Complexes
- 23 December 2008
- journal article
- review article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 131 (3), 1208-1221
- https://doi.org/10.1021/ja808149k
Abstract
The four-coordinate heteroleptic complex [Fe-III((F)pda(2-))((F)dad(*-))] (1) and its homoleptic analogue [Fe-II((F)dad(*-))2] (2), where (F)pda(2-) is the closed-shell ligand N,N'-bis(pentafluorophenyl)-o-phenylenediamide(2-) and (F)dad(*-) is the singly reduced N,N'-bis(pentafluorophenyl)-2,3-dimethyl-1,4-diazabutadiene pi-radical anion, have been synthesized. X-ray crystallographic studies reveal a twisted tetrahedral geometry of the FeN4 coordination polyhedron in both 1 and 2. The electronic structures of 1 and 2 were probed by magnetic susceptibility measurements, Fe-57 Mossbauer and electronic spectroscopy, and density functional theory (DFT) calculations. In spite of their similar geometries and a common triplet ground state (S-t = 1), the electronic structures of 1, 2, and the previously reported homoleptic analogue [Fe-III((F)pda(2-))((F)pda(*-))] (3), where (F)pda(*-) is a one-electron-oxidized form of (F)pda(2-), differ. The electronic structure of 2 consists of two (F)dad(*-) radicals coupled antiferromagnetically to a high-spin Fe-II center, whereas in 3, only one (F)pda(*-)radical is coupled antiferromagnetically to an intermediate-spin Fe-III ion. This ligand mixed-valent species exhibits class-III behavior. Heteroleptic 1 contains a single (F)dad(*-) radical coupled antiferromagnetically to an intermediate-spin Fe-III center but behaves as a class-II ligand mixed-valent species. The observed diversity in the electronic structures of 1-3 is ascribed to the difference in the redox potentials of the ligands. Analysis of reduced orbital charges and spin densities obtained from DFT calculations also suggests that the electronic structures of 1-3 are best described as either a high-spin Fe-II ion coordinated to two radical monoanions (2) or as an intermediate-spin Fe-III ion coordinated to one radical monoanion and one closed-shell dianion (1, 3).Keywords
This publication has 113 references indexed in Scilit:
- Characterization of Three Members of the Electron‐Transfer Series [Fe(pda)2]n (n=2−, 1−, 0) by Spectroscopy and Density Functional Theoretical Calculations [pda=Redox Non‐innocent Derivatives of N,N′‐Bis(pentafluorophenyl)‐o‐phenylenediamide(2−, 1.−, 0)]Chemistry – A European Journal, 2008
- (α-Diimine)chromium Complexes: Molecular and Electronic Structures; A Combined Experimental and Density Functional Theoretical StudyInorganic Chemistry, 2008
- Bis(α-diimine)iron Complexes: Electronic Structure Determination by Spectroscopy and Broken Symmetry Density Functional Theoretical CalculationsInorganic Chemistry, 2008
- A Four-Coordinate Fe(III) Porphyrin CationJournal of the American Chemical Society, 2008
- Electronic Structure of Square Planar Bis(benzene-1,2-dithiolato)metal Complexes [M(L)2]z (z = 2−, 1−, 0; M = Ni, Pd, Pt, Cu, Au): An Experimental, Density Functional, and Correlated ab Initio StudyInorganic Chemistry, 2005
- Redox-Noninnocence of the S,S‘-Coordinated Ligands in Bis(benzene-1,2-dithiolato)iron ComplexesJournal of the American Chemical Society, 2005
- Molecular and Electronic Structure of Four‐ and Five‐Coordinate Cobalt Complexes Containing Two o‐Phenylenediamine‐ or Two o‐Aminophenol‐Type Ligands at Various Oxidation Levels: An Experimental, Density Functional, and Correlated ab initio StudyChemistry – A European Journal, 2004
- Reactivity of “GaI” Toward N-Substituted 1,4-Diazabuta-1,3-dienes: Synthesis and Characterization of Gallium Heterocycles Containing Paramagnetic Diazabutadiene MonoanionsOrganometallics, 2002
- Theoretical and experimental study of diamagnetic and paramagnetic products from thermal and light-induced alkyl transfer between zinc or magnesium dialkyls and 1,4-diaza-1,3-butadiene substratesJournal of the American Chemical Society, 1991
- Bis(1,4-di-tert-butyl-1,4-diazabutadiene)gallium is not a gallium(II) compoundJournal of the Chemical Society, Chemical Communications, 1991