Below 250 K, the T value of 29 started decreasing and attained a value of 0.24 cm 3 K mol -1 at 120 K, that gave clear evidence of complete spin transition with T1/2 =205 and 226 K in cooling and heating processes, respectively possessing a thermal hysteresis loop of ~21 K indicated an increased lattice cooperative effect among the metal centers due to the guests solvent loss. geometry where Fe(II) centers was connected by four equatorial Npyridyl atoms of two L23 ligands, and two axial N atoms of NCX -coligands. Since, L23 is planar, so these 2D grids exhibited interesting planer geometry (Fig. ).