Helical transition-metal compounds: preorganisation of the ligands by a paracyclophane group

The figure-of-eight twist to macrocycles: preorganization, self-organization and dynamics

“…1. 27 The copper()-donor distances and the valence angles around the metal centers and the donor groups (see Table 2 for the relevant structural data) are as expected for this type of co-ordination compound, that is the observed geometry is relatively unstrained and, therefore, the paracyclophane anchor group might not be required for the folding to a figure-of-eight shaped geometry of this type of ligand. Indeed, the geometry of the dicopper() product of the large macrocyclic ligand para-222 (32-membered macrocycle), whose experimental structure is also given in Fig.…”

“…Recently, a new type of macrocyclic Schiff base compound with (N 2 S 2 ) 2 (bis-dithiadiimine) donor sets has been reported which, upon co-ordination to two copper() ions, leads to double helical figure-of-eight shaped folding (see Chart 1). [25][26][27][28][29] The solid state structural properties of these dicopper() compounds have been studied as a function of the chelate ring sizes and the substitution pattern of the phenylene spacer groups (see Table 1). 28 A preorganized ligand, based on a tetrasubstituted paracyclophane anchor group, has also been prepared and studied for comparison (Table 1).…”

“…28 A preorganized ligand, based on a tetrasubstituted paracyclophane anchor group, has also been prepared and studied for comparison (Table 1). 27 The solution structures and dynamics have been investigated with high-field and variable temperature 1 H NMR spectroscopy, respectively. 28 The experimentally determined isomer and conformer equilibria have been compared to the computed ratios based on force field calculations.…”

“…nitromethane) is used. [25][26][27][28] In the simplest example for 1 H NMR spectroscopy, that of para-Ph2Ph, which has only one type of methylene proton, there is one sharp singlet for these protons in the metal-free ligand. In the helical dicopper() compound these become diastereotopic and give rise to a four line AX system at 200 MHz, with a geminal coupling of 10.5 Hz and a chemical shift difference of ∆δ = 1.5 ppm (the vicinal coupling that would give rise to an AAЈXXЈ pattern is not observed).…”

Metal Ion Promoted Synthesis of Hexaaza[17]paracyclophane Derived from Terephthalaldehyde Involving Co(II), Ni(II), Cu(II), and Zn(II) and Their Physico‐chemical Properties

“…Macrocyclic polyethers incorporating the aryl group of the [2,2] paracyclophane nucleus and p-phenylene subunits in the macro-ring have been synthesized by the appropriate use of phenols, tetraethylene or pentaethylene glycol dichlorides, or tosylates. The complexing behaviour of these macrocyclic polyethers provide a new dimension to host guest complexation.…”