The structural and spectroscopic characterisation of 2-aryl and 2-heteroaryl isatogens.
This work reviews the current knowledge of the synthesis ,
properties , structures and biological activities of
The unequivocal 2 C NMR assignment of 2-phenylisatogen 1S
reported and used to assign the spectra for a range of
Molecular dynamics of 2-phenylisatogen in chloroform are
reported and indicate that there is little if any inter-ring
mesomeric resonance in this compound.
1~C , ~N NMR and UV-Visible spectroscopic data are reported
for a range of 2-(4-substituted-phenyl)isatogens. Analysis
of this data indicates a small but significant degree of
inter-ring mesomeric resonance is present in these compounds
especially those with strongly electron donating or
withdrawing substituents. An interesting correlation is
found between ~sN substituent chemical shifts and molar
absorbtivity of the visible transitions. The X-ray crystal
structure of 2-(4-chlorophenyl)isatogen is reported and
shows a small but significant shortening of the inter-ring
bond length compared to 2-phenylisatogen , further
supporting the hypothesis of inter-ring mesomeric resonance
in these compounds.
1 H and ~C NMR data are reported for the 2-(pyrid-2-inium)isatogen
cation and indifate the presence of intramolecular
interaction between the ~---H and N~O groups in the
molecule. The X-ray crystal structure of the perchlorate
salt of the cation and the ~H solid state NMR spectrum both
support this conclusion. The molecular structure indicates
that the intramolecular interaction is comprised of
coulombic and hydrogen bonding interactions leading to a
near coplanar structure for the cation compared to the noncoplanar
structure for the parent base, 2-(pyrid-2-yl)isatogen.
A hypothesis is put forward to explain molecular packing
and configuration differences in 2-heteroarylisatogens. The
molecular packing and configuration is controlled by a
balance of intermolecular dipole attraction and repulsion.
Predictions of molecular packing and configuration are made
for a number of 2-heteroarylisatogens. The X-ray crystal
structure of 2-(pyrid-3-yl)isatogen is reported and found to
be in complete agreement with the predictions of the
Further studies are proposed involving the synthesis of ~N
and ~~O labelled isatogens , the study of inclusion
complexes with cyclodextrins and the study of isatogens with
the potential for increased mesomeric interactions.