Adducts of transition metal complexes with redox-active ligands: the structure and spin-state-switching rearrangements

Abstract

The currently available literature data on the synthesis, molecular and electronic structure of mixed-ligand complexes (adducts) of transition metals (chromium, manganese, iron, cobalt, ruthenium) with organic redox-active ligands are systematically considered for the first time. The possibility of manifestation of magnetic bistability by adducts of tetracoordinate CoII and FeII complexes and the potential for their application as molecular switches are studied in detail by means of quantum chemical modelling of thermally initiated rearrangements controlled by the spin crossover and valence tautomerism mechanisms. Special attention is given to dinuclear adducts of CoII and FeII complexes with linearly bonded and polycyclic di-o-quinones and their imines, which can operate as thermally switchable elements of quantum computers suitable for practical implementation of two-qubit gates. The bibliography includes 183 references.

Rational Design of Electronically Labile Dinuclear Fe and Co complexes with 1,10‐Phenanthroline‐5,6‐Diimine: A DFT study

“…Based on the experimental data and earlier performed theoretical investigations, one can assume that the most interesting magnetic properties would be manifested by the dinuclear systems IV , in which diimine fragment of the tetradentate ligand is coordinated to the cobalt ion, while phenanthroline (phen) moiety is bound with the iron center. Such type complexes are potentially capable of occurrence of the VT Co II /Co III and SCO LS Fe II / HS Fe II rearrangements.…”

“…Diimine fragment of this ligand is suitable for the construction of VT systems with cobalt bis‐chelates . It might be expected that directional variation of the metal centers could lead to dinuclear compounds, spin states of which are controlled by the two mentioned above mechanisms (SCO and/or VT).…”

Uranyl‐Bound Tetra‐Dentate Non‐Innocent Ligands: Prediction of Structure and Redox Behaviour Using Density Functional Theory

“…Thus, the incoming electron preferentially enters or is trapped into an energetically low‐lying stabilized ligand‐based delocalised orbital. Whilst this has been well‐documented for transition metal systems, only a few actinide systems have been reported …”

“…Thus, the incoming electron preferentially enters or is trapped into an energetically lowlying stabilized ligand-based delocalised orbital. Whilst this has been well-documented for transition metal systems, [12][13][14][15][16] only a few actinide systems have been reported. [7,9,[17][18][19][20][21][22] For example, whilst examining the VI to V reduction potentials of actinyl ([AnO 2 ] 2 + ; An=U, Np and Pu) alaskaphyrin complexes, Shamov et al [9] identified ligand reduced species for the one-electron reduction of a [U VI O 2 -alaskaphyrin] complex rather than the anticipated [U V O 2 -alaskaphyrin]species.…”

“…However, these coordinating ligands of TM complexes are preferentially oxidized despite the presence of d-electrons on the metal cation. [16] [27] In this work we shall use DFT to study the uranyl(VI/V) reduction potentials of uranyl-salmnt complexes (UO 2 -salmnt-L) in DCM solution recently experimentally determined by Hardwick et al [30] The 'salmnt' ligand is a tetra-dentate Schiff base ligand and it occupies the equatorial plane of the uranyl ion, with the fifth coordination site of the uranyl ion is available for a mono-dentate ligand. This coordination mode of the 'salmnt' ligand with the uranyl ion is shown in Figure 1.…”