Rank the carbon-metal bond in the following organometallic reagents in order of decreasing polarity, starting with the most polar. $$\begin{array} { c c c }
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { MgBr } & \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Li } & \left( \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \right) _ { 2 } \mathrm { CuLi } \
\text { I } & \text { II } & \text { III }
\end{array}$$

Question

Rank the carbon-metal bond in the following organometallic reagents in order of decreasing polarity, starting with the most polar. $$\begin{array} { c c c } 
\mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { MgBr } & \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \mathrm { Li } & \left( \mathrm { CH } _ { 3 } \mathrm { CH } _ { 2 } \right) _ { 2 } \mathrm { CuLi } \
\text { I } & \text { II } & \text { III }
\end{array}$$

Quizplus · Accepted Answer

The polarity of the carbon-metal bond is determined by the difference in electronegativity between carbon and the metal. Lithium (Li) is less electronegative than magnesium (Mg), making the C-Li bond in II more polar than the C-Mg bond in I. Copper (Cu) is more electronegative than both Li and Mg, making the C-Cu bond in III the least polar. Therefore, the order is II > I > III.

Rank the Carbon-Metal Bond in the Following Organometallic Reagents in Order