  Triangular lattice quasi-two-dimensional Mott insulators based on BEDT-TTF
molecule and its analogies present a possibility to produce exotic phases by
coupling charge and spin degrees of freedom. In this work we discuss magnetic
properties of one of such materials, $\kappa$-(BEDT-TTF)$_2$Hg(SCN)$_2$Cl,
which is found at the border of the phase transition between a Mott insulator
into a charge ordered state. Our magnetic susceptibility and cantilever
magnetisation measurements demonstrate how the charge degree of freedom defines
magnetic properties for few different charge phases observed in this material
as a function of temperature. Between $T_{CO}=30~K$ and $T_S=24~K$ we observe
charge and spin separation due to one-dimensional charge stripes formed in this
material below $T_{CO}=30~K$. Below $T_S=24~K$ charge and spin degrees of
freedom demonstrate coupling. Spin singlet correlations develop below 24~K,
however melting of charge order below 15~K prevents the spin singlet state
formation, leaving the system in the inhomogeneous state with charge ordered
spin singlet domains and charge and spin fluctuating ones.
