Problem 54 - Chemistry: An Atoms-Focused Approach

Question

What do the prefixes cis- and trans-mean in the context of a square planar complex?

Step-by-Step Solution

Answer

Answer: In the context of a square planar complex, the prefixes cis- and trans- indicate the relative positions of the ligands in the complex. Cis- denotes that two identical ligands are adjacent to each other, or on the same side, while trans- indicates that two identical ligands are positioned opposite to each other, or on opposite sides of the complex.

Step 1: Define a Square Planar Complex

A square planar complex is a type of coordination complex where the central metal atom is surrounded by four ligands in a square plane. In this configuration, the metal ion is located at the center of the square, and the ligands are positioned at the vertices of the square. Square planar complexes are common for metal ions with a d8 electron configuration, such as Ni(II), Pt(II), and Pd(II) complexes.

Step 2: Define cis- and trans- prefixes

In the context of a square planar complex, cis- and trans- are prefixes used to indicate the relative positions of the ligands on the complex. - Cis: The cis- prefix denotes that two identical ligands (or groups) are adjacent to each other, or in other words, they are located on the same side of the complex. - Trans: The trans- prefix indicates that two identical ligands (or groups) are positioned opposite to each other, or in other words, they are located across the central metal atom or on the opposite side of the complex.

Step 3: Provide examples of cis- and trans- complexes

Let's take the examples of two square planar complexes involving Platinum (Pt) and two different ligands A and B: 1. Cis-[Pt(AB)2]: In this complex, the two A ligands are adjacent to each other (on the same side) and the two B ligands are also adjacent to each other. This is an example of a cis- configuration. 2. Trans-[Pt(AB)2]: In this complex, the two A ligands are opposite to each other (across the central Pt atom), and the two B ligands are also opposite to each other. This is an example of a trans- configuration. In conclusion, the prefixes cis- and trans- in the context of a square planar complex describe the relative positions of the ligands in the complex, with cis- meaning the ligands are on the same side and trans- meaning they are on opposite sides.