Q10.50P - Chemistry: Molecular Nature Of Matter And Change

Question

Because both tin and carbon are members of Group 4A(14), they form structurally similar compounds. But tin exhibits a greater variety of structures because it forms several ionic species. Predict the shapes and ideal bond angles, including any deviations:

(a)  $\mathbf{Sn}\mathbf{(}\mathbf{C}{\mathbf{H}}_3{\mathbf{)}}_2^{}$

(b) $\mathbf{Sn}\mathbf{(}\mathbf{Cl}{\mathbf{)}}_3^{-}$

(c)  $\mathbf{Sn}\mathbf{(}\mathbf{C}{\mathbf{H}}_3{\mathbf{)}}_4^{}$

(d)  ${\mathbf{SnF}}_5^{-}$

(e)  ${\mathbf{SnF}}_6^{-}$

Step-by-Step Solution

Answer

The shapes and bond angles of molecules can be determined from the VSEPR theory. The deviations in observed bond angles arise mainly due to lone pair repulsion around the central atoms.

Step 1: Sn ( Cl ) 3 -

The Sn atom is ${\mathbf{sp}}^3$  hybridized with an expected angle of  $\mathbf{109}\mathbf{.}{\mathbf{5}}^o$. The two lone pairs on the Sn atom reduce the bond angle lower than the expected value.

Step 2: Sn ( Cl ) 3 -

The Sn atom is ${\mathbf{sp}}^3$  hybridized with a pyramidal shape and expected angle of  $\mathbf{109}\mathbf{.}{\mathbf{5}}^o$. The lone pairs on Sn atom reduce the bond angle lower than the expected value. 

Step 3: Sn ( C H 3 ) 4

The Sn atom is ${\mathbf{sp}}^3$ hybridized with a bond angle of  $\mathbf{109}\mathbf{.}{\mathbf{5}}^o$. The shape of the molecule is Tetrahedral.

Step 4: SnF 5 -

The Sn atom is  ${\mathbf{sp}}^3\mathbf{d}$ hybridized with an expected angle of  ${\mathbf{90}}^o$. The shape of the molecule is square pyramidal.

Step 5: SnF 6 -

The structure is octahedralwith excepted bond angle of ${\mathbf{90}}^o$ .