Chapter 3, Problem 12P

Interpretation Introduction

Interpretation:

The following species (a) ${\text{BF}}_{\text{3}}$ (b) ${\text{SiF}}_4$ (c) ${\text{XeF}}_4$ (d) ${\text{PF}}_{\text{5}}$ (e) ${\left[{\text{XeF}}_{\text{5}}\right]}^{-}$ (f) ${\text{SF}}_6$ (g) ${\text{C}}_{\text{2}}{\text{F}}_{\text{4}}$ (h) ${\text{H}}_{\text{2}}{\text{C=C=CH}}_{\text{2}}$, contain inversion centres or not is to be determined.

Concept Introduction:

The number and nature of the symmetry elements of a given molecule are conveniently represented by its point groups and give rise to labels such as ${\text{D}}_{\text{3h}}$, ${\text{T}}_{\text{d}}$, $O_h$, ${\text{D}}_{\text{2d}}$, ${\text{C}}_{\text{2}}$, ${\text{C}}_{\text{3v}}$ etc.

These point groups belongs to the classes of C groups, D groups and special groups, the latter containing groups that has special symmetries, i.e. octahedral, tetrahedral and icosahedral.

A centrosymmetric molecule or ion contains a centre of symmetry and non-centrosymmetric molecule or ion does not contain a centre of symmetry.