The X-ray crystal structure of a novel Schiff base macrocycle containing a tricyclic (7 + 12 + 7) inner ring system

Abstract

The product from the reaction of 2,6-diacetylpyridine with o-phenylenediamine contains one 1 2-membered and two 7-membered inner rings and not a single 18-membered inner ring as proposed by others.We have previously describedl some mononuclear nontransition metal complexes of the conjugated 18-membered hexadentate 'NB' macrocycle L1 derived from the cyclic (2 + 2) Schiff base condensation of 2,6-diformylpyridine with o-phenylenediamine. X-Ray analysis of the CdII and PbII complexes established that the co-ordinated macrocycle has a near planar hexagonal structure of hole radius ca. 2.7 A suitable for the complexation of large metal ions (ionic diameter ca. 2.2-2.7 A) but not for first row transition metal ions2 having ionic diameters less than 2.0 A. Attempts to

One-pot conversion of tetraiminodiphenols to diiminodiaminodiphenols via methyl transfer at aluminium

“…They all contain the same generic motif 1,3- 5). [33][34][35][39][40][41][42][43] and the bis(imino)benzyl (compounds VIII-X and XIV, from 1.254 (7) to 1.274 Ǻ) [36][37][38]40,43 derivatives. This is owing to the intramolecular hydrogen bonds occurring systematically in bis(imino)phenol based macrocyclic Schiff bases.…”

“…The ν C=N for 1 (1629 cm -1 ) and 2 (1627 cm -1 ) lie within the range of the reported data for other macrocyclic Schiff bases. 18,[33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] Although ν N-H vibrations for compound II (3282 cm -1 ) 45 and for compound XII (3336 cm -1 ) 33,34 are reported as discrete bands, 2 exhibits a large band at 3300 cm -1 .…”

Synthesis and spectral characterization of macrocyclic NiII complexes derived from various diamines, NiII perchlorate and 1,4-bis(2-carboxyaldehydephenoxy)butane

“…This importance is due to both the kinetic and thermodynamic stabilities of their complexes [14,15]. Synthesis of these Schiff-base complexes is achieved through the template reaction [16][17][18][19] or transmetallation reactions [20][21][22][23] which are used when the transition metal cations are ineffective as templates. In the present work, we have synthesized six macrocyclic Schiff base complexes by template effect by reaction of 1,4-bis(2-carboxyaldehyde phenoxy)butane and various diamines; Ni(ClO 4 ) 2 AE 6H 2 O. Spectral, magnetic properties of the new compounds were studied in detail.…”