Neglecting pairing energy I. [Mn(CN)6]3−⇒Mn3+,t2g4,CFSE=−0.4×4∆o =−1.6∆o II. [Co(CN)6]4−⇒Co2+,t2g6egg1,CFSE=−0.4×6+ 0.6×1=−1.8∆∘ III. [Fe(CN)6]4−⇒Fe2+,t2g6eg0,CFSE=−0.4×6= −2.4∆∘ IV. [Fe(CN)6]3−⇒Fe3+,t2g5eg0,CFSE=−0.4×5= −2∆∘ Order of stability III>IV>II>I
