Interactions of trivalent lanthanide cations with tetradentate Schiff bases. Synthesis and characterization of lanthanide(III) complexes with N,N′-bis(pyridin-2-ylmethylene)benzene-1,2-diamine

Interactions of trivalent lanthanide cations with tetradentate Schiff bases: New lanthanide(III) complexes from (1S,2S,N1E,N2E)–N,N′-bis(pyridin-2-ylmethylene)cyclohexane-1,2-diamine

“…1a) consists of dimeric hydrogen bonded [Pr(NO 3 ) 3 (MeOH)L] 2 units held together with stacking interactions between the pyridine rings. The Pr III atom is surrounded by seven oxygen atoms belonging to three bidentate chelating nitrato ligands and a coordinated methanol and four (two imino and two pyridine) nitrogen atoms belonging to the Schiff base ligand.The Pr-O bond distances span the range 2.562-2.763 Å and they are in good agreement with previously reported values [5,6,[15][16][17][18], taking into account the lanthanide contraction. Though neutral, the methanol moiety appears to be coordinated to Pr III stronger than the nitrates (mean Pr-O nitrato = 2.642, Pr-O methanol = 2.562 Å ).…”

“…They can be considered symmetrically chelated and the Pr atom is coplanar to all of them, since all the Pr-O coordinated -N-O free are larger than 170°. The mean Pr-N distance is 2.680 Å , and is in agreement with our previous data [17,18]. The 4N group of atoms deviates from the planarity as a result of the trans geometry of the cyclohexane moiety and the Pr atom is positioned 1.01 Å outside of the best fitted plane.…”

“…These complexes are stable enough under physiological conditions. However, only recently, research work dealing with the various aspects involving different physicochemical properties and complexation behaviour of tetradentate Schiff bases has appeared in the literature, primarily focusing in the separation of actinides from lanthanides in nuclear reprocessing [15] and catalytic properties [16].Previously, we have reported the synthesis and the structural and spectroscopic characterization of lanthanide complexes with N,N 0 -bis[1-(pyridin-2-yl)ethylidene]ethane-1,2-diamine [17] and N,N 0 -bis(pyridin-2-ylmethylene)benzene-1,2-diamine [18].It was found that the ethylenediamine 'hinge' of the diSchiff base ligand eliminates the possibility of coplanar coordination of the four nitrogen donors [17] while when we changed the ethytlenediamine moiety with 1,2-1387-7003/$ -see front matter Ó (N. Hadjiliadis), iplakatu@ cc.uoi.gr (J.C. Plakatouras). …”

“…Previously, we have reported the synthesis and the structural and spectroscopic characterization of lanthanide complexes with N,N 0 -bis[1-(pyridin-2-yl)ethylidene]ethane-1,2-diamine [17] and N,N 0 -bis(pyridin-2-ylmethylene)benzene-1,2-diamine [18].…”

Polymeric Membrane Silver-ion Selective Electrodes Based on Schiff Base N,N'-Bis(pyridin-2-ylmethylene)benzene-1,2-diamine

“…previously. 23 A solution of 0.1 mol 1,2-diaminobenzene was slowly added to 0.2 mol 2-pyridinecarboxaldehyde in ethanol under nitrogen atmosphere. After 3 h at room temperature, the precipitate was collected by filtration.…”