Question

Select the correct statement (s) for following molecules:
(I) $P{F}_2(C{H}_3{)}_3$
(II) $P{F}_2(C{F}_3{)}_3$

• A. Both have trigonal bipyramidal structure
• B. Both have the same dipole moment
• C. $P-F$ bond length is longer in $P{F}_2(C{H}_3{)}_3$ than in $P{F}_2(C{F}_3{)}_3$
• D. $P-F$ bond length is longer in $P{F}_2(C{F}_3{)}_3$ than in $P{F}_2(C{H}_3{)}_3$

Answer 1

Answer: (A), (B), (C)

The correct options are
A Both have trigonal bipyramidal structure
B Both have the same dipole moment
C $P-F$ bond length is longer in $P{F}_2(C{H}_3{)}_3$ than in $P{F}_2(C{F}_3{)}_3$

$\text{Hybridization of}P:s{p}^{3}d$
Hence, shape; trigonal bipyramidal

$\text{Hybridization of}P:s{p}^{3}d$
Hence, shape trigonal bipyramidal
(b) ${\mu }_D$ of both $I$ and $II$ is equal to zero as all substitutents are symmetrically arranged.
(c) According to Bent's rule, $P-F$ bond length in $P{F}_{2}M{e}_3$ is longer than $P{F}_2(C{F}_3{)}_3$ because as a whole group $C{F}_3$ is more electronegative than $C{H}_3$ group by which polarity of $P-F$ bond increases in $P{F}_2(C{F}_3{)}_3$ and $P-F$ bond length decreases.