Self-assembled Transition Metal Coordination Frameworks of ...

Chapter 2
0.86 A with Uiso = 1.2 Ucq of the parent atoms, except H(3AN), H(4AN) and H(4BN)
which were located from difference maps and were refined isotropically.
The data of HZL4 were collected at X-ray Crystallography Unit, School of
Physics, Universiti Sains Malaysia, Penang, Malaysia using Bruker SMART APEX2
CCID area detector diffractometer equipped with graphite monochromated Mo K010» =
0.71073 A) radiation at temperature 297(2) K. The trial structure was solved using
SHELXS-97 and refinement was carried out by full-matrix least squares on F2
(SHELXTL-97). H atoms attached to N atoms were located in a difference map and
refined isotropically. C-bound H atoms were placed in calculated positions and
allowed to ride on their parent c atoms, with C—H = 0.93 A and u.,.,(H) = 1.2u,.,(c).
The crystallographic data and structure refinement parameters for the
compounds HZL3 and HZL4 are given in Table 2.3. The graphics tools used include
ORTEP-III [26], PLATON [27], MERCURY [28] and DIAMOND version 3.0 [29].
2.3.4.1. Crystal structure of HZL3
The compound HZL3, C2,H,6N6S, crystallizes in triclinic form with two
independent molecules in the asymmetric unit and exists in the thione tautomeric
forms. The two crystallographically independent molecules, A and B are depicted in
Fig. 2.16 and their bond lengths and angles are given in Table 2.4, agree with each
other and are within normal ranges [30]. Molecule A shows a Z-Z configuration about
the C(l0A)—N(2A) and C(12A)—N(5A) double bonds and molecule B shows the same
about the C(l0B)—N(2B) and C(l2B)—N(5B) double bonds. A similar configuration
was observed in the bisthiocarbohydrazone of 2-benzoylpyridine, HZL2 [1 1], while in
2-acetylpyridine analogue an E-Z configuration exists [9]. The thione S(l) atom is
positioned trans to azomethine atom N(2) [The S(l)—C(l l)—N(3)—N(2) torsion angle
of -l74.72(2)° for molecule A and l77.67(2)° for molecule B] and cis to azomethine
atom N(5) [The S(l)—C(l1)—N(4)—N(5) torsion angle of 4.26(3)° for molecule A and
1.43(3)° for molecule B] in both molecules.
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