The T vs. T measurements were performed for 30 and 31 under externally applied dc magnetic field of 1000 Oe from 300-1.8 K (Fig. and). For 30, the T = 3.45 cm 3 mol -1 K at 300 K suggested single isolated HS Fe(II) ion containing remarkable orbital contribution. While decreasing the temperature till 190 K, T value was fixed and then gradually lowered to 2.75 cm 3 K mol -1 around 50 K with a T1/2 = 110 K, suggesting the occurrence of incomplete and gradual SCO in 30 (Fig. ). Then the T value was dropped abruptly upon decreasing the temperature below 50 K to 1.31 cm 3 mol -1 K at 1.8 K, which might be due to the zero-field splitting (ZFS) of residuary HS Fe(II) centers or the antiferromagnetic interactions involving the adjacent Fe(II) centers (Fig. ). In the case of 31, the T remained constant at 3.47 cm 3 mol -1 K within 300-180 K. As the temperature reduced to 80 K, T sharply decreased to 0.73 cm 3 mol -1 K and reached a plateau at 0.56 cm 3 mol -1 K till 12 K, indicating that 31 underwent a one-step but incomplete SCO having T1/2 of 144 K. This fast decrease in T value below 12 K was also because of the ZFS of the residuary HS Fe(II) centers or the antiferromagnetic interaction among Fe(II) centers (Fig. ). Also, exothermic and endothermic peaks at around 147 K in DSC measurement during heating and cooling cycles matched well with the T1/2 of SCO . Magnetic susceptibility data for the partially desolvated vacuum and (31)vacuum samples, revealed that the SCO in vacuum and (31)vacuum could be prompted by the solvents, and more fractions of HS Fe(II) centers were situated at the low-temperature region while the SCO temperature for (31)vacuum didn't change with the removal of solvents.