Self-assembled Transition Metal Coordination Frameworks of ...

Chapter 6
strong v(C=S) bands of free ligands H2L' and HZL2 seen ~l224 cm" are found to suffer
negative shifts, which is more in 31 suggesting the possible deprotonated thiolate
sulfur coordination. However this shift is marginal in the case of 30 attributed to the
thione sulfur coordination. The spectrum of 31 is given in Fig. 6. 23.
J
100­60- ‘
40­
20­
0 '1 ' | ' | ' | ' | ' I ' | ' I
4000 3500 3000 2500 2000 1500 1000 500
Wavenumber (cm")
Fig. 6.23. IR spectrum of Cd(H) thiocarbohydrazone compound 31.
6.3.3. Single crystal X-ray diffraction study
An X-ray crystallographic study can unequivocally confirm the formation of
tetranuclear molecular square complexes. Fortunately we could isolate single crystals
of compound 29 from its chloroform methanol mixture solution. All attempts to
crystallize other complexes, however, went in vain. The X-ray diffraction study of 29,
the first example of a molecular square through self-assembly from a carbohydrazone
ligand [32], confirms the formation of square grid and agrees well with MALDI mass
results.
The data of 29 were collected at X-ray Crystallography Unit, School of
Physics, Universiti Sains Malaysia, Penang, Malaysia using Bruker SMART APEX2
CCD area detector diffractometer equipped with graphite monochromated Mo K010» =
0.71073 A) radiation at temperature 100 K (Oxford Cyrosystems Cobra low
temperature attachment). The trial structure was solved using SHELXS-97 [38] and
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