  Single crystalline and polycrystalline samples of $S=1/2$ Kagom\'{e} lattices
{[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpe)_{3}$](ClO$_{4}$)$_2$}$_{n}$ and
{[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpy)_{3}$](ClO$_{4}$)$_2$}$_{n}$, respectively were
synthesized. Their structural and magnetic properties were characterized by
means of x-ray diffraction and magnetization measurements. Both compounds
crystalize in a hexagonal structure (space group $P-6$) consisting of CuO$_4$
Kagom\'{e} layers in the $ab$-plane but linked along $c$ direction through
either rigid $bpy$ or flexible $bpe$ ligands to form 3D frame works. Magnetic
measurements reveal that both the compounds undergo ferromagnetic ordering
($T_{\rm C}$) at low temperatures and the $T_{\rm C}$ and the extent of
frustration could be tuned by changing the nature of the pillar ligands.
{[Cu$_{3}$(CO$_{3}$)$_{2}$$(bpe)_{3}$](ClO$_{4}$)$_2$}$_{n}$ which is made up
of flexible $bpe$ ligands has a $T_{\rm C}$ of 5.7 K and a Curie-Weiss
temperature ($\theta_{\rm CW}$) of -39.7 K giving rise to a frustration
parameter of $\frac{|\theta_{\rm CW}|}{T_{\rm C}} \simeq$ 6.96. But the
replacement of $bpe$ by a more rigid and electronically delocalized $bpy$
ligand leads to an enhanced $T_{\rm C} \simeq$ 9.3 K and a reduced frustration
parameter of $\frac{|\theta_{\rm CW}|}{T_{\rm C}} \simeq$ 3.54.
