Question

Which of the following statements is/are not correct?

• A. The bond angle Si-O-Si in $(Si{H}_3{)}_{2}O$ is larger than that of C–O–C in $(C{H}_3{)}_{2}O$
• B. $B{F}_3$ has more Lewis acidic nature than $B{I}_3$
• C. $p\pi -d\pi$ bond electrons get delocalized between B and N atoms in $B_3{N}_3{H}_6$
• D. $C{H}_{3}NCS$ is linear, while $Si{H}_{3}NCS$ is bent structure

Answer 1

Answer: (B), (C), (D)

$C{H}_{3}NCS$ is linear, while $Si{H}_{3}NCS$ is bent structure

A) The bond angle Si-O-Si in $(Si{H}_3{)}_{2}O$ is larger than that of C–O–C in $(C{H}_3{)}_{2}O$. This is because, the lone pair of O is involved in back bonding with Si.

B) Due to efficient overlap of $2\pi -2\pi$ overlap, the extent of back bonding is more in $B{F}_3$ than in $B{I}_3$. Hence $B{F}_3$ is less acidic than $B{I}_3$.
C) $p\pi -p\pi$ bond electrons get delocalized between B and N atoms in $B_3{N}_3{H}_6$.
D) The lone pair of N in $Si{H}_{3}NCS$ is involved in backbonding with Si and hence the shape is linear. Since Carbon carbon can exhibit back bonding, $C{H}_{3}NCS$ is bent.