Toshiaki Tsukuda

Synthesis, spectroscopic and magnetic properties of lanthanide(III) complexes with a chelated imino nitroxide radical

The treatment of [Ln(hfac)3(H2O)2] (Ln(III) = Y, Nd–Lu) with IM-2py (2-(2-pyridyl)-4,4,5,5-tetramethyl-1H-imidazolyl-1-oxyl) readily gave a series of novel rare earth or lanthanide radical complexes [Ln(hfac)3(IM-2py)]. The molecular structures of the Sm, Gd, Dy, Er and Yb complexes have been determined to be bicapped trigonal prismatic (TPRS) by X-ray diffraction. The magnetic susceptibility data for [Gd(hfac)3(IM-2py)] show that the Gd–IM-2py interaction is weakly antiferromagnetic with an exchange coupling constant J = −3.00 cm−1 in contrast to the ferromagnetic interaction in the Gd(III)–nitronyl nitroxide complexes. The n–π* transition of IM-2py is found to shift to lower frequency associated with intensity enhancement and vibronic structure. The luminescence measurement of the Eu(III) and Tb(III) complexes demonstrated energy transfers for IM-2py (SOMO π*) → Ln(III) (4f) as a result of emission quenching; this depends on the energy gap between the excited levels in Ln(III) and IM-2py. These results reveal that the metal–radical interactions are very weak magnetically but are relatively strong with respect to energy transfer.

Synthesis and Properties of Lanthanide(III) Complexes Containing Pyridine-Substituted Imino Nitroxide Radical

Some lanthanide(III) complexes containing three types of a chelated n-methylpyridine-substituted imino nitroxide radical IM n Me2py( n =4,5,6) were synthesized with a small size of the multi-spin system. X-ray structural analysis of [Gd(hfac) 3 (IM6Me2py)], [Dy(hfac) 3 (IM4Me2py)] demonstrated that they are rigidly eight-coordinted with one IM n Me2py and three hfac ligands. Magnetic susceptibility measurements of the Gd(III) complexes indicate that the antiferromagnetic interaction between Gd(III) and imino nitroxide radical is different from the other lanthanide complexes containing nitronyl radicals. lanthanide imino nitroxide radical crystal structures magnetic interaction

Synthesis and characterization of a series of bis(L-tartrate)-bridged dinuclear transition metal complexes with 2,2′-bipyridine

Seven bis(L-tartrato)-bridged dinuclear metal complexes with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen), [ (L-tartH)2(bpy or phen)2] · 4H2O (M = Fe, Mn) or [ (L-tartH2)2(bpy or phen)2] · nH2O (M = Ni, Co, Cu), where L-tart4− is C4H2 , were synthesized and characterized by the elemental analysis and ESI-mass spectra or powder X-ray patterns. These are the first examples of discrete dinuclear complexes with bpy or phen except for Cr(III) complexes. The protonation of the hydroxyls of the coordinated tartrate systematically changes with the variation of the metal ionic radii, the smaller ionic radii of the central metal, the smaller number of the protons in the hydroxyl groups of the bridging tartrates. The magnetic properties are discussed in connection to analogous Cr(III), Cu(II), and V(IV)O complexes.

[μ-1,2-Bis(diphenyl­phosphan­yl)benzene-κ2P:P′]bis­[chloridogold(I)]

In the crystal structure of the non-solvate form of the title compound, [Au2Cl2(C30H24P2)], two almost linear P—AuI—Cl units [175.87 (3) and 171.48 (3)°] are in a skewed arrangement with a Cl—Au⋯Au—Cl torsion angle of −65.29 (3)° so as to form an intramolecular Au⋯Au interaction [3.0563 (2) Å]. The complex molecules are connected each other through intermolecular C—H⋯π interactions, giving a sheet structure parallel to the bc plane.