Nicotinate N-oxide complexes with dipositive 3d metal ions

Abstract

AIC5037 11Divalent 3d metal complexes with nicotinate N-oxide (N-nicO), of the type M(N-nicO)rxHzO (M = Mn-Zn; x = 4 or 5 ) , were synthesized by reaction of the corresponding metal(I1) acetates or ferrous ammonium sulfate with ammonium nicotinate N-oxide. The characterization of the new metal complexes was based on spectral, magnetic, and x-ray powder diffraction studies and their solubility characteristics. These compounds appear to be hexacoordinated, linear, polynuclear complexes of the type [M(N-nic0)2(0H2)2],.mH20 (m = 2n for M = Mn, Fe, Co, Ni, Cu; m = 3n for M = Zn), probably involving double M(N-nicO)zM bridges. The N-nicO ligands coordinate through the N-0 oxygen and one of the COO oxygens, while the other carboxylate oxygen is hydrogen bonded to water. Lattice water is also present in these complexes.Desiccation of the preceding compounds over PzOs, under reduced pressure, leads to their partial or complete dehydration.Under these conditions, only lattice water is eliminated from the Mn(II), Ni(II), and Cu(I1) complexes, without occurrence of any structural change. The Fe(I1) and Co(I1) complexes are completely dehydrated, while the Zn(I1) complex loses the lattice water and one aquo ligand per Zn2+ ion. Co(N-nic0)z seems to maintain coordination number 6, by the function of N-nicO as a tridentate bridging ligand, in a highly cross-linked polymeric structure. Fe(N-nic0)2 and Zn(N-nicO)yHzO appear to be pentacoordinated, comprising chemically nonequivalent carboxylate groups; evidence favors the presence of both bi-and tridentate N-nicO bridging ligands in the Fe(I1) complex and hydrogen-bonding of the uncomplexed COO oxygen of part of the bidentate ligands in the Zn(I1) complex. N-nicO is a ligand of strength about equal to that of picolinate N-oxide.

Lanthanide(III) Complexes of Oxamic Acid

“…The absence of a weaker broad continuous absorption, covering the whole 3600-3150 cm -1 region, indicates that lattice water (in addition to the aqua ligands) is not present [45]. The presence of co- ordinated water is also confirmed by the appearance of the w(H20) mode [46].…”

“…In the r(OH)water region the spectra exhibit a strong, single and sharp band at 3380 cm -1 , attributable to the presence of coordinated aqua ligands [45]. The absence of a weaker broad continuous absorption, covering the whole 3600-3150 cm -1 region, indicates that lattice water (in addition to the aqua ligands) is not present [45].…”

Synthesis, Characterization and Fluorescence of N,N′‐Bis(6‐methyl‐2‐pyridinecarboxylamide‐N‐oxide)‐1,2‐ethane and Corresponding Rare Earth(III) Complexes

“…189 -1908C, yield 50% This compound exhibited a melting point and IR spectra identical with those of previous reference. [14] Preparation of Methyl 6-Methyl-2-pyridine carboxylate-N-oxide (2) A suspension of L 0 (4.59 g, 30 mmol), chloroform (50 mL), and methanol (50 mL) was stirred for 20 min at room temperature. To this solution was added a fresh thionyl chloride (10 mL) dropwise over a period of 0.5 hr in an ice bath with stirring, and then the stirring was continued for another 0.5 hr at room temperature.…”

“…Terms & Conditions of access and use can be found at http:// www.tandfonline.com/page/terms-and-conditions INTRODUCTION Picolinic acid N-oxide and its substituted derivatives are able to form many complexes with various metals. [1,2] A number of the complexes of picolinic acid N-oxide with lanthanide ions have been investigated. Previously, [3 -5] we had synthesized some binary and ternary lanthanide complexes of 6-methylpicolinic acid N-oxide, and found the Eu 3þ complexes have stronger fluorescent intensity than that of the other rare earth(III) complexes, such as Tb, Sm, Dy, etc.…”

Συνθεση Και Μελετη Πεπτιδιων Της Κυστεινης Και Των Συμπλοκων Τους Με Δισθενη Μεταλλικα Ιοντα

“…Γ.2.2.1 και Γ.2.3.1 αποδίδονται σε v(Cu-S)[364,365] και v(Cu-Cl) αντίστοιχα[366][367][368]. Επίσης η απορρόφηση στα 436 cm" 1 αποδίδεται κατά τα γνωστά σε δόνηση της μορφής V(CU-O H 0 )[369][370]. Τέλος σύμφωνα με τους W.L.…”