Self-assembled Transition Metal Coordination Frameworks of ...

Chapter 2
The carbohydrazone moiety C(6)/N(3)/N(4)/C(12)/O(l)/N(5)/N(6)/C(13) is
approximately planar, with a maximum mean plane deviation of -0.0937( 16) A for
N(5), similar to bis(methyl 2-pyridyl ketone)carbohydrazone. The pyridine ring planes
N(2)/C(7)-C(11) [Cg(2), having a maximum mean plane deviation of -0.009l(l9) A
for C(10)] and N(7)/C(14)-C(18) [Cg(3), having a maximum mean plane deviation of
0.0065(l9) A for C(18)] are twisted away from the carbohydrazone plane by 40.88(5)
and 50.lO(4)° respectively, while the N(l)/C(l)-C(5) [Cg(l), with a maximum mean
plane deviation of 0.0l45(l7) A for C(2)] and N(8)/C(19)-C(23) [Cg(4), with a
maximum mean plane deviation of -0.01l0(l8) A for C(22)] pyridine ring planes are
twisted by 23.92(7) and 2l.45(7)° respectively. The decrease in the twisting is
attributed to intramolecular N-H---N hydrogen bonds (Fig. 2.19). The dihedral angle
between the N(l)/C(l)-C(5) and N(2)/C(7)-C(11) mean planes is 55.75(6)° and that
between the N(7)/C(14)-C(18) and N(8)/C(19)-C(23) mean planes is 7l.03(5)°.
lntramolecular N—H---N hydrogen bonds (Table 2.8) involving H(lN4)
generate rings of graph-set motifs S(5) and S(6) [35], similar to those in bis(methyl 2­
pyridyl ketone) carbohydrazone [9] and in related thiocarbohydrazones [9,l 1], while
the N—H---N hydrogen bond involving H(lN5) generates a graph-set motif S(6), as
seen in related thiocarbohydrazone [1 1]. As a consequence the angles subtended at
C(6), C(12) and C(13) (Table 2.7) vary significantly. Molecules translated by one unit
cell along the a-axis direction are linked by C(2)—H(2A)---0(1) and C(16)­
H(l6A)---O(1) (Table 2.8) hydrogen-bonding interactions, forming a chain (Fig. 2.20).
These interactions together constitute a pair of bifurcated acceptor bonds. In addition,
the crystal packing is reinforced by a weak C-1-I---1: interaction (Table 2.8) involving
the N(8)/C(19)-C(23) pyridine ring [centroid Cg(4)] and 1c---1: stacking interactions
involving the N(l)/C(1)-C(5) pyridine rings [centroid Cg(l)] at (x, y, z) and (2-x, 2-y,
-z) [Cg---Cg distance=3.5804(9) A]. Another week 1:---1: stacking interactions between
pyridine rings Cg(l) at (x, y, z) and Cg(4) at (2-x, 1-y, -z) [Cg---Cg distance
=3.7785(10) A] and its counterpart are also observed in the packing.
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