Which of the following is/are the limitations of Werner's Theory?

All of these

The correct answer is option 4. All of these.

Let us delve deeper into each limitation of Werner's Theory:

1. Colour of the Complexes:

Werner's Theory does not explain why coordination compounds exhibit a wide range of colors. The colors of these compounds are due to electronic transitions between different energy levels. Specifically, the absorption of visible light promotes electrons from lower energy d-orbitals to higher energy d-orbitals (d-d transitions). These transitions and the resulting colors are better explained by Crystal Field Theory (CFT) and Ligand Field Theory (LFT), which take into account the splitting of d-orbitals in the presence of a ligand field.

2. Nature of Bonding in Complexes:

Werner's Theory primarily focuses on the coordination number and the spatial arrangement of ligands around the central metal ion. It categorizes complexes into primary (ionizable) and secondary (non-ionizable) valence spheres. However, it does not explain the nature of the metal-ligand bond, such as whether the bond is ionic, covalent, or involves a combination of both. Modern theories like Valence Bond Theory (VBT), Crystal Field Theory (CFT), and Molecular Orbital Theory (MOT) provide detailed insights into the bonding interactions by considering orbital hybridization, electronic configurations, and molecular orbitals.

3. Magnetic Properties of the Complexes:

The magnetic properties of coordination complexes are influenced by the presence of unpaired electrons in the d-orbitals of the central metal ion. Werner's Theory does not address how these unpaired electrons are distributed or how they contribute to the overall magnetic behavior of the complex. Crystal Field Theory (CFT) explains how the splitting of d-orbitals in different geometries (octahedral, tetrahedral, etc.) affects the number of unpaired electrons, thereby determining whether a complex is paramagnetic (has unpaired electrons) or diamagnetic (all electrons are paired).

Summary:

Werner's Theory laid the groundwork for understanding the structures of coordination compounds, but it falls short in explaining the following aspects:

Color: Does not account for electronic transitions that cause color.

Nature of Bonding: Does not explain the specific type and nature of metal-ligand bonds.

Magnetic Properties: Does not account for the arrangement of unpaired electrons and their magnetic effects.

Thus, the limitations of Werner's Theory encompass its inability to explain the color, nature of bonding, and magnetic properties of coordination complexes. This is why the correct answer to the question regarding its limitations is: All of these.