Introduction to Radical Ligands

At low temperatures and in solution the complex is comprised of Co3+ and singly reduced trianion-radical ligands.

New magnetic metal complexes with organic radical ligands, [M(hfac)2(PyBTM)2] (M = NiII, CoII; hfac = hexafluoroacetylacetonato, PyBTM = (3,5-dichloro-4-pyridyl)bis(2,4,6-trichlorophenyl)methyl radical), were prepared and their crystal structures, magnetic properties, and electronic structures were investigated.

During the preparation of the lanthanide complexes, the nitronyl nitroxide radical ligands NIT-6-X-Py (2-(6-X-2-pyridyl)-4,4,5,5-tetramethylimidazolyl-1-oxyl-3-oxide; X = F, Cl, Br) were reduced to the non-radical ligands HIM-6-X-Py, forming mononuclear lanthanide complexes with two HIM-6-X-Py ligands chelated to one lanthanide(III) ion.

The results show that all aromatic thiol-radical ligands caused significant structural distortion in the geometries.

The structures of complexes 1 and 2 were elucidated by single-crystal X-ray structural analysis and the results show that both complexes consist of [Ln-NIT-Ln-NIT]n one-dimensional chains and the additional Cu ions are coordinated to the nitrogen atoms from the triazole rings of the radical ligands.

An [Ru(apy)2Cl2] precursor (apy = 2,2′-azopyridine) in 2-methoxyethanol was heated under a pressurized CO atmosphere to afford a diradical complex, [Ru(apy·−)2(CO)2], containing one-electron-reduced azo anion radical ligands.

Incorporating radical ligands into metal complexes is one of the emerging trends in the design of single-molecule magnets (SMMs).

The self-assembly of Mn(II) metal ions with 1 leads to the formation of [Mn(hfac)2]3(1)2 that exhibits a Mn(II)-radical-Mn(II)-radical-Mn(II) linear arrangement of three Mn(hfac)2 units bridged by two radical ligands (hfac = 1,1,1,5,5,5-hexafluoroacetylacetonato-).

While [Cu(L1) 2 ] + is best described as a Cu I complex with two neutral radical ligands that couple antiferromagnetically, [Cu(L2) 2 ] + is a Cu I complex with two clearly different ligand units in the solid state and with a magnetic susceptibility close to a diamagnetic compound.

The central CuII ion is six-coordinated in tensile octahedron configuration finished by two bidentate radical ligands and one bidentate hfac anion, while TbIII ion exhibited as distorted triangular dodecahedron geometry (D2d) finished by eight oxygen atoms from four bischelate hfac anions.

Particular attention is paid to the relation between different types of radical ligands and how to tune the magnetic properties of those magnetic families.