Syntheses and crystal structures of neodymium(III) and europium(III) complexes bearing dimethyl-, pyrrolidine-, or S-prolinol- dithiocarbamato ligands and their natural and magnetic circular dichroism spectra

Abstract

A series of Nd III and Eu III complexes containing achiral or chiral dithiocarbamato (dtc) ligands, [Ln(Xdtc)3(NN)] {Ln = Nd or Eu; X = dimethyl-(Me2), pyrrolidine-(pyr), or (S)-prolinol-(S-proOH); NN = 1,10-phenanthroline (phen) or 2,2'-bipyridine (bpy)}, were prepared and their crystal structures and spectroscopic properties, in particular the natural circular dichroism (CD) and magnetic circular dichroism (MCD), were investigated. The crystal structures of the complexes analyzed by the X-ray diffraction method showed an 8-coordinate geometry around the Ln III center with comparable structural parameters to one another and to the related complexes reported previously. These complexes exhibited similar spectral patterns in their absorption, natural CD and MCD spectra in solution. Weak but characteristic sharp f-f transition bands were observed in the absorption and MCD spectra, but no CD signals associated with these transitions were observed even in the S-proOHdtc complexes. The MCD spectral pattern of the Eu III complexes revealed a local C2v symmetry around the Ln III center in solution, in contrast to the aqua and the analogous β-diketonato Eu III complexes.

Homodinuclear lanthanoid(III) dithiocarbamato complexes bridged by 2,2′-bipyrimidine: Syntheses, structures and spectroscopic properties

“…The molecular structures of 1a and 2a have a similar core structure (Figure 1), in which each Ln III center is 8-coordinated by three bidentate S,S-donating Me2dtcligands with a chelating and bridging bpm ligand in a κ 2 N 1,1' :κ 2 N 3,3' bonding mode. The coordination geometry around each Ln III center is similar to those of previously reported 1,10-phenathroline and 2,2'-bipyridine coordinated mononuclear analogues [17]. The two pyrimidine rings of the bridging bpm ligand are almost planar (mean deviation of each atom from the plane is 0.010(5)…”

“…The complexes were prepared by a similar procedure (Scheme 1) to that for mononuclear 2,2'bipyridine (bpy) and 1,10-phenanthroline (phen) complexes [17]. To a mixture of 2,2'bipyrimidine, bpm (1.00 mmol) and sodium dimethyldithiocarbamate, Na(Me2dtc) or ammonium pyrrolidine dithiocarbamate, NH4(pyrdtc) (3.00 mmol) in MeOH (20 mL) was added a methanol solution (10 mL) of LnCl3•6H2O (Ln = Nd or Eu) (1.00 mmol).…”

“…However, interests in these complexes have recently resurfaced for practical applications in catalysis, nanotechnology, and microelectronics [11,12]. For examples, syntheses, crystallographic and spectroscopic characterizations of mononuclear lanthanoid complexes of various dialkyl-substituted dithiocarbamates with 1,10-phenanthroline (phen) and 2,2'bipyridine (bpy) have been reported [13][14][15][16][17]. In a previous study [17], we have investigated the crystal structures and spectroscopic properties of the Nd III and Eu III complexes containing chiral or achiral dithiocarbamates.…”

“…For examples, syntheses, crystallographic and spectroscopic characterizations of mononuclear lanthanoid complexes of various dialkyl-substituted dithiocarbamates with 1,10-phenanthroline (phen) and 2,2'bipyridine (bpy) have been reported [13][14][15][16][17]. In a previous study [17], we have investigated the crystal structures and spectroscopic properties of the Nd III and Eu III complexes containing chiral or achiral dithiocarbamates. In particular, their natural circular dichroism (CD) and magnetic circular dichroism (MCD) spectra were discussed in relation to the coordination environment and electronic structure around the lanthanoid center, because Nd III and Eu III often…”

A hexanuclear Nd (III) complex derived from a Schiff base with significant antitumor and antifungal activity

“…[ 22 ] Although some lanthanide complexes are widely studied, examples of Nd (III) complexes are still limited to a few reports, which are mainly focused on structures, redox, luminescence, magnetic, thermodynamics properties, and catalyst reactivity. [ 9,23‐27 ] Further studies about Nd (III) complexes based on Schiff base ligand are still worth discussing to explore their antitumor and antifungal activities. 4‐Aminoantipyridine is a widely used pharmaceutical intermediate, which can produce Schiff bases simply by condensation reaction.…”