Ligand control of low-frequency electron paramagnetic resonance linewidth in Cr(iii) complexes

Abstract

Understanding how the ligand shell controls low-frequency electron paramagnetic resonance (EPR) spectroscopic properties of metal ions is essential if they are to be used in EPR-based bioimaging schemes. In this...

Rhodium(III) Werner Complexes with 1,2‐Diphenylethylenediamine Ligands: Syntheses, Structures, and Applications as Chiral Hydrogen Bond Donor Catalysts and Agents for Enantiomer Purity Determinations

“…exhibit this geometry. [13,14] The crystal structure of Λ-(S,S)-4 3 + 3Cl À • 6DMSO (Figure 2) is very similar to that of the tris(iodide) cobalt analog Λ-(S,S)-3 3 + 3I À • 6DMSO described earlier. [12a] Although the cobalt complex lacks crystallographic symmetry and the unit cell contains two independent molecules, the hydrogen bonding interactions are essentially identical, with minor differences in the array of carbon-hydrogen bonds interacting with the chloride ion that is not bound to a C 3 face (or any other NH group).…”

“…Upon crystallization from DMSO, the trisolvate [Ni( S , S ‐dpen) 3 ] 2+ 2ClO 4 − ⋅ 3DMSO is obtained, with the unit cell featuring a 50 : 50 mixture of Λ/Δ diastereomers [13] . An identical motif has been found with crystalline [Cr( R , R ‐dpen) 3 ] 3+ 3Cl − ⋅ DMSO ⋅ 3CH 3 OH ⋅ 0.5CH 3 CH 2 OH [14] …”

“…For the elusive Rh Δ /6C S diastereomers, the N C H 2 ‐ C H 2 N bonds should lie roughly in a plane perpendicular to the C 3 axis, in what is termed a ob 3 orientation. Accordingly, the Ni Δ /6C S dication in Λ,Δ‐[Ni( S , S )‐dpen) 3 ] 2+ 2ClO 4 − ⋅ 3DMSO and the Cr Λ /6C R trication in Λ,Δ‐[Cr( R , R ‐dpen) 3 ] 3+ 3Cl − ⋅ DMSO ⋅ 3CH 3 OH ⋅ 0.5CH 3 CH 2 OH exhibit this geometry [13,14] …”

“…Although there are many rhodium complexes that contain chelates with NCHPhCHPhN segments in the literature, we were unable to find any tris(dpen) adducts. Among other metals, only the nickel(II) species Λand Δ-[Ni(S,S-dpen) 3 ] 2 + 2ClO 4 À [13] and paramagnetic chromium(III) analogs Λand Δ-[Cr(R,Rdpen) 3 ] 3 + 3Cl À [14] were located, as treated further below. However, rhodium(III) complexes with three 1,2-propanediamine, 2,3-butanediamine, or trans-1,2-cyclohexanediamine ligands have been described.…”

Ligand design of zero-field splitting in trigonal prismatic Ni(ii) cage complexes

“…1 Top Right). [22][23][24] Furthermore, this property could be leveraged for chemical sensing: changes in ligand field (e.g. from ligand-based protonation reactions or changes in metal-ion Fig.…”