Conformational Aspects of Chelate Rings

Electrochemical Investigation of Transition—Metal Complexes of the Ligand Tetrakis(2-Pyridylmethyl)-Ethylenediamine (Tpen). Crystal Structure of [Ni(tpen)](CIO4)2·2/3H2O

“…The ethylenediamine backbone of molecules 1 and 2 have torsion angles N21-CI31-C131'-N21' and N22-C132-C262-N52 of 60.9" and -57.8", respectively, with the usual gnrrclte configuration. 22 The five-membered rings Nil-N21-C131-C131'-N51 and Ni2-N22-C132-C262-N52 cannot deviate greatly from planarity due to ring strain.…”

Synthesis and Spectroscopic Characterisation of a Heterodinuclear Iron(III)‐Copper(II) Complex Based on an Asymmetric Dinucleating Ligand System

“…The thermodynamic driving force for preferential binding to the bis(2-pyridylmethyl)amino site arises because of its ability to form more favored five-membered chelate rings, [12] as opposed to the six-membered chelate rings arising from binding to the bis(2-pyridylethyl)amino moiety. This ligand possesses two distinct metalbinding sites: a preferential metal-binding site provided by the bis(2-pyridylmethyl)amino moiety and a second binding site involving the bis(2-pyridylethyl)amino group.…”

“…This ligand possesses two distinct metal‐binding sites: a preferential metal‐binding site provided by the bis(2‐pyridylmethyl)amino moiety and a second binding site involving the bis(2‐pyridylethyl)amino group. The thermodynamic driving force for preferential binding to the bis(2‐pyridylmethyl)amino site arises because of its ability to form more favored five‐membered chelate rings,12 as opposed to the six‐membered chelate rings arising from binding to the bis(2‐pyridylethyl)amino moiety. The unsymmetrical nature of FloH allows the site‐directed generation of a heteronuclear Fe III Cu II complex in high yield.…”

Absolute configuration of glycerol derivatives. 3. Synthesis and Cupra A circular dichroism spectra of some chiral 3-aryloxy-1,2-propanediols and 3-aryloxy-1-amino-2-propanols

“…22 Based on the model studies of Bukhari,12-16 the S-diol-Cupra A complexes are assigned the X conformation (-chirality according to Dillon and Nakanishi29•30), and the Rdiol-Cupra A complexes then have the conformation (+ chirality), assuming that the aryloxyalkyl substituent occupies the equatorial position, as would be expected. 37 Although the absolute configuration of the diols seems readily assignable on the basis of either of the observed bands, the short-wavelength one, Xmax ~280 nm, is considered to be more reliable primarily because of its greater intensity. The transition in the ultraviolet region was also considered more reliable in 1 -phenyl-2 -alkylaminoethanols by Mitscher.22 The assignments are in agreement with results of his study22 of the effect of various N substituents on CD spectra of these amino alcohols.…”