## General Chemistry: Principles and Modern Applications (10th Edition)

$[\mathrm{Cr}(\mathrm{EDTA})]^{-}$ form chelates in a single step, while $\left[\mathrm{Cr}(\text { en })_{3}\right]^{3+}$ form chelates in three steps. The $\beta_{1}$ for $[\mathrm{Cr}(\text { EDTA })]^{-}$ is much greater than $\beta_{1}$ or $\beta_{2}$ of $\left[\mathrm{Cr}(\mathrm{en})_{3}\right]^{3+},$ but the cumulative formation constant, $\beta_{3}\left(\text { or } K_{\mathrm{f}}\right),$ of $\left[\mathrm{Cr}(\mathrm{en})_{3}\right]^{3+}$ is similar to $\beta_{1}\left(\text { or } K_{\mathrm{f}}\right)$of $[\mathrm{Cr}(\mathrm{EDTA})]^{-}$.