Geometrical isomers are a type of stereoisomers that differ in the spatial arrangement of atoms around a double bond or a ring. In other words, geometrical isomers have the same molecular formula and connectivity but exhibit different geometric arrangements. They are characterized by the presence of a double bond or a ring in their structure.

**Types of Geometrical Isomers:**

There are two main types of geometrical isomers:

**1. Cis-Trans Isomers:**
Cis-trans isomers, also known as E-Z isomers, occur when two different groups are attached to each carbon atom of a double bond or a ring. In cis isomers, the substituent groups are on the same side of the double bond or ring, while in trans isomers, the substituent groups are on opposite sides.

**2. Eclipsed and Staggered Isomers:**
Eclipsed and staggered isomers occur in cyclic compounds, particularly in rings with three or more carbon atoms. Eclipsed isomers have substituent groups that are aligned directly with each other, while staggered isomers have substituent groups that are staggered or offset from each other.

**Relationship with Diastereomers and Enantiomers:**

a) Diastereomers or Enantiomers: Geometrical isomers can be diastereomers or enantiomers, depending on the specific arrangement of substituent groups.

- Diastereomers: When multiple stereoisomers are possible but not mirror images of each other, they are called diastereomers. Geometrical isomers can be diastereomers if they have more than one chiral center or if they possess other types of stereoisomerism in addition to the geometrical isomerism.

- Enantiomers: Enantiomers are mirror images of each other and are non-superimposable. Geometrical isomers cannot be enantiomers because enantiomers require the presence of chiral centers.

**Not Structural Isomers:**

b) Structural isomers: Geometrical isomers are not structural isomers. Structural isomers have different connectivity and molecular formula. Geometrical isomers, on the other hand, have the same connectivity and molecular formula but differ in the spatial arrangement of atoms.

**Not Interconvertible at Room Temperature:**

c) Geometrical isomers are not interconvertible at room temperature. Unlike conformational isomers, which can rapidly interconvert due to rotation around single bonds, geometrical isomers have a restricted rotation around double bonds or within rings. This restricted rotation makes it difficult for geometrical isomers to interconvert spontaneously at room temperature.

**Conclusion:**

In conclusion, geometrical isomers can be diastereomers or enantiomers, but they are not structural isomers. They are characterized by different spatial arrangements of atoms around a double bond or a ring. Geometrical isomers are not interconvertible at room temperature due to restricted rotation.