Question

The AsF₅ molecule is trigonal bipyramidal. The hybrid orbitals used by the As atoms for bonding are:

• A. ${\mathrm{dx}}^2-{\mathrm{y}}^2,{{\mathrm{d}}_{\mathrm{z}}}^2,\mathrm{s},\mathrm{px},\mathrm{py}$
• B. $\mathrm{dxy},\mathrm{s},\mathrm{px},\mathrm{py},\mathrm{pz}$
• C. ${\mathrm{dx}}^2-{\mathrm{y}}^2,\mathrm{s},\mathrm{px},\mathrm{py}$
• D. s, px, py, pz, dz²

Answer 1

The correct option is D

s, px, py, pz, dz²

Explanation for correct option

Option d) $\mathrm{s},{\mathrm{p}}_{\mathrm{x}},{\mathrm{p}}_{\mathrm{y}},{\mathrm{p}}_{\mathrm{z}},{\mathrm{d}}_{{\mathrm{z}}^2}$

• ${\mathrm{AsF}}_5$ has ${\mathrm{sp}}^3\mathrm{d}$hybridisation.
• ln ${\mathrm{sp}}^3\mathrm{d}$hybridisation, the ${\mathrm{d}}_{{\mathrm{z}}^2}$orbital is used along with one ‘s’ and three ‘p’ orbitals to form three equatorial bonds
• And two equally strong axial bonds for a trigonal bipyramid.

Explanation for incorrect option

Option a) ${\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2},{\mathrm{d}}_{{\mathrm{z}}^2},\mathrm{s},{\mathrm{p}}_{\mathrm{x}},{\mathrm{p}}_{\mathrm{y}}$

• As the complex show ${\mathrm{sp}}^3\mathrm{d}$ hybridisation
• Hence this arrangement is not proper .This option is incorrect

Option b) ${\mathrm{d}}_{\mathrm{xy}},\mathrm{s},{\mathrm{p}}_{\mathrm{x}},{\mathrm{p}}_{\mathrm{y}},{\mathrm{p}}_{\mathrm{z}}$

• As the complex involve ${\mathrm{d}}_{{\mathrm{z}}^2}$- orbital in hybridisation
• Thus option is incorrect

Option c) ${\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2},\mathrm{s},{\mathrm{p}}_{\mathrm{x}},{\mathrm{p}}_{\mathrm{y}}$

• Since in hybridisation $As{F}_5$ do not invlove ${\mathrm{d}}_{{\mathrm{x}}^2-{\mathrm{y}}^2}$
• Hence option is incorrect

The hybrid orbitals used by the $\mathrm{As}$ atoms for bonding are $\mathrm{s},{\mathrm{d}}_{{\mathrm{z}}^2},{\mathrm{p}}_{\mathrm{x}},{\mathrm{p}}_{\mathrm{y}},{\mathrm{p}}_{\mathrm{z}}$