Macrocyclic nickel(II) complexes with new, dimethyl-substituted 13- and 14-membered tetraaza ligands

Abstract

Catalytic reduction of the diimine linkages of 11,13-dimethyl-1,4,7,10-tetraazacyclotrideca-11,13-dienenickel(II) hexafluorophosphate, [Ni( [ 13 ] dieneNa)] (PF6)2, and 12,14-dimethyl-1,4,8,11 -tetraazacyclotetradeca-12,14-dienenickel(II) hexafluorophosphate, [Ni( [ 14]dieneN4) ] (PFe) 2, in aqueous solution over Raney nickel yields Ni(II) complexes containing the fully reduced, dimethyl-substituted macrocyclic ligands. Conversion of the PFe™ salts to NO3™ derivatives has been accomplished by column chromatography. Compounds with a variety of other anions have been prepared by metathetical reactions on solutions of the NO3" complexes. Ten new complexes have been characterized on the basis of elemental analyses, conductivity and magnetic susceptibility measurements, and infrared and electronic spectral studies. [Ni([13]aneN4)]X2 and [Ni([ 14]aneN4)]X2 where X™ = PFe™ and L contain singlet ground-state Ni(II) and the planar forms of both macrocyclic ligands. Axial coordination occurs when X™ = Cl™, Br™, and NO3™ and complexes of formulation [Ni([14]aneN4)X2] have been characterized as high spin tetragonal. Two complexes, [NÍ2([13]aneN4)20x](PF6)2 and [Ni2([14]aneN4)20x](PF6)2, are dimers which contain oxalato bridging groups. These two compounds, along with monomeric [Ni([14]aneN4)(SCN)2],exhibit pseudooctahedral Ni(II) spectral characteristics and must contain folded forms of the macrocyclic ligands. Analysis of electronic spectral data for the tetragonal complexes gives a Dq*y of 1470 cm™1 for the dimethyl-substituted 14-membered ligand. This value is nearly the same as that reported for cyclam which leads us to conclude that substitution of two methyl groups on the cyclam ring has negligible steric and electronic effects.

A new macrocyclic polystyrene-based sensor for chromium (III) ions

“…In IR spectra, the characteristic bands for the ligand appeared in the region 1630-1660 cm -1 and were assigned as C=N vibrations [9,10]. The observed adsorption bands in the visible and ultraviolet regions were also recorded (not given in this manuscript) and the spectral behaviour was consistent with the square planer co-ordination [11] of the compound.…”

Synthesis and Characterization of Bis(Macrocyclic) Nickel(II) Complexes Containing Aromatic Nitrogen–Nitrogen Linkers Produced by Template Condensation

“…Cyclic voltametry data summarized in Table 2, show that oxidation and reduction potentials of the Ni(II) complexes of (6)-(10) do not differ significantly from those of [14]aneN 4 complexes [16, [20][21][22][23][24][25]. This suggests that macrocycles (6)-(10) have Lewis basicities and hole size similar to those of the [14]aneN 4 ligand in spite of the structural differences.…”

Macrocyclic metal complexes: synthesis and characterization of 14- and 16- membered tetraaza macrocyclic complexes of transition metals

“…spectra of the [ML 1 X 2 ] and [ML 2 X 2 ] complexes are presented in Table 1. Structure (1) exhibits a m str NH band at 3250 cm À1 , a m str CN band in the 1600-1639 cm À1 region, as well as the m str CO of secondary amide bands, which is due to overlapping of these two bands [11,12]. Structure (2) exhibits m str C@N bands in the 1575-1630 cm À1 region and the absence of uncondensed functional groups (ANH 2 , C@O).…”