The Synthesis, Structures, and Solution Equilibria of Bis(pyrrole-2-aldimino)metal(II) Complexes

Abstract

Et -Ed. c ß = KiKiK$ for bipy and K,K% for terpy. d Estimated.12 diethylenetriamine complexes.The corresponding ratio for the zinc and cadmium complexes is only 1.2, Bis (pyrrole-2-aldimino) metal (II) Complexes 625 suggesting that terpyridine chelates comparatively more weakly with these metal ions. It is unlikely, however, that they are acting as bidentate ligands only, since the structure of Zn (terpy) Cl2 shows that all three nitrogens coordinate with only minor strain.13 Although there are puzzling features which certainly require further examination, nevertheless a good deal of understanding now exists in this particular area. We are turning our attention to solvents other than water as well as metal ions such as chromium(II) and vanadium(II), for which there is a paucity of data.

Syntheses and characterization of neutral complexes of Zn(II) with mono- and dianionic pyrrole-2-imine ligands [(pyrrole-2-CHN)nR]n− (n = 1, 2)

“…The filtrate was concentrated by evaporating the solvent to dryness. The white solid was washed with diethyl ether (3 X 10 ml) yielding pure Zn2(l) 2 …”

“…The complex Zn(pyrrole-2-CH=N-t-Bu)s has already been prepared by Holm and co-workers [2] and some crystallographic data, such as space group (Pbcn) and cell constants have been published [7]. In order to investigate the coordination properties of the pyrrole-2-CH=N-moieties to zinc(I1) in more detail we solved the X-ray structure of complex 3 (see ref.…”

“…Such 2/l ligand-to-metal complexes can provide information on the coordination behaviour of the monoanionic pyrrole-imine moieties with zinc(I1) in solution and show how two such bidentates present in the (N;N2)2-dianions cooperate when they bind to the metal centres. Holm et al 2 …”

“Embroidered” Square Pyramidal Coordination Caps for Nickel(II): Mono-, Di- and Tetrafunctionalisation of a Tetrapodal Pentadentate Ligand with an NN4 Donor Set

“…[17] [18] The difficulties in isolating a complex of the salicylaldimTherefore, whereas salicylaldimines usually lose a proton ine quarter-unit 4 led us to study the condensation reaction upon metal complexation to become uninegative ligands, β-of 1 with 1 equiv. of a related carbonyl substrate, acetylketoamines may be either uninegative or neutral in their acetone (2,4-pentanedione).…”

Structure of a bis-bidentate metal complex, bis-(N-t-butylpyrrole-2-carbaldimino)nickel(II). Analysis of its configurational disorder in the crystalline state

“…complexes, bis-(N-t-butylpyrrole-2-carbaldimino)M(II) (M=Co, Ni, Cu, and Zn) (Holm, Chakravorty & Theriot, 1966;Wei, 1972b), the structural analysis of the nickel complex was previously undertaken from a set of three-dimensional photographic data (Wei, unpublished work). The results showed that the overall structure of the nickel complex was similar (but not isomorphous) to that of the analogous cobalt complex (Wei, 1972a) except that the NiN4 coordination was more distorted so as to be less tetrahedral.…”