Abstract: The equilibrium study of the reactions of [(1-5- -2 MeOC6H6) Fe (CO)3]BF4 with 4-dimethylaminopyridine, 2-aminopyrimidine and P-toluidine was studied in nitromethane at room temperature spectrophotometrically. The results show that the rate of reaction is dependent on the basicity of nucleophiles with the rate of reaction decreasing in the order 4-dimethylaminopyridine > 2-aminopyrimidine > P-toluidine. Our findings also indicate that the forward reactions are being favored than the reverse dissociation reactions since Keqm>1 in each case.