Question

Draw all the structural formulas for the octahedral complexes of \(\left[\mathrm{Ni}\left(\mathrm{H}_{2} \mathrm{O}\right)_{3}(\mathrm{OH})_{2} \mathrm{Cl}\right]\)

Short answer

Question: Draw all the structural formulas for the octahedral complexes of [Ni(H2O)3(OH)2Cl]. Answer: There are three possible structural formulas for the octahedral complexes of [Ni(H2O)3(OH)2Cl]: 1. OH | Ni / \ H2O - Cl | | H2O H2O 2. OH | Ni / \ H2O - Cl | \ H2O OH 3. OH | Ni / \ Cl - OH | \ H2O H2O

Step-by-step solution

Understand octahedral complex geometry

In an octahedral complex, the central metal ion is surrounded by six ligands with 90° angles between adjacent ligands. Looking at the Ni(II) ion in our exercise, it is coordinated with 3 water molecules (H2O), 2 hydroxide ions (OH-), and 1 chloride ion (Cl-).

Determine the number of possible isomers

To show all the possible structural formulas for an octahedral complex of [Ni(H2O)3(OH)2Cl], we need to consider all the possible arrangements of the ligands around the central metal ion. There are a total of 6 coordination sites, and we have 3 different types of ligands, so we will have to check every possible combination.

Draw the first octahedral complex

In the first isomer, we can place the 3 water molecules at the equatorial positions, and the 2 hydroxide ions along with the chloride ion at the axial positions. OH | Ni / \ H2O - Cl | | H2O H2O

Draw the second octahedral complex

In the second isomer, we can place the 3 water molecules at the axial and the cis-equatorial positions, and the 2 hydroxide ions along with the chloride ion at the remaining positions. OH | Ni / \ H2O - Cl | \ H2O OH

Draw the third octahedral complex

In the third isomer, we can place the 3 water molecules at the axial and one equatorial position, and the 2 hydroxide ions along with the chloride ion at the remaining positions. OH | Ni / \ Cl - OH | \ H2O H2O We have now successfully drawn all the possible structural formulas for the octahedral complexes of [Ni(H2O)3(OH)2Cl].

Key concepts

Coordination Chemistry

Coordination chemistry is a field of chemistry that examines how atoms or groups of atoms, known as ligands, can coordinate or bind to a central metal atom to form complex compounds. These compounds, referred to as coordination complexes, are distinctive due to the specific orientation of ligands around the central metal atom.

For instance, in the complex \[\mathrm{Ni}(\mathrm{H}_2 \mathrm{O})_3(\mathrm{OH})_2 \mathrm{Cl}\], nickel (Ni) acts as the central metal atom, and it's surrounded by three ligands: water (H2O), hydroxide (OH-), and chloride (Cl-). The specific way these ligands are arranged around nickel is what gives this particular complex its unique properties and reactions. Coordination complexes play a crucial role in various areas of chemistry, including biochemistry, where they form part of vital processes in living organisms.

To thoroughly understand these complexes, it's necessary to explore their geometric configurations, which can have significant implications on their chemical behavior and applications.

Geometric Isomers

Geometric isomers are different forms of the same compound that have the same chemical formula but differ in the arrangement of their atoms or groups of atoms in space, particularly relating to the geometry surrounding a central atom. This phenomenon is commonly observed in coordination chemistry.

For the octahedral complex in the exercise, \[\mathrm{Ni}(\mathrm{H}_2 \mathrm{O})_3(\mathrm{OH})_2 \mathrm{Cl}\], there are various ways to arrange the ligands around the central nickel ion. This leads to the formation of distinct geometric isomers. The process to determine these isomers involves exploring all possible permutations in which these ligands can be organized, considering the geometry of an octahedral structure. Geometric isomers have different physical and chemical properties and can be used to explain the behavior of complex molecules in diverse scenarios, such as industrial catalysis or pharmaceuticals.

Understanding how to identify and draw these isomers, like in the provided step-by-step solution, is essential for students studying coordination chemistry, allowing them to predict and explain the properties of various coordination complexes.

Ligand Arrangement

Ligand arrangement refers to the specific positioning of ligands around a central metal atom within a coordination complex. The spatial arrangement of these ligands is vital as it influences the reactivity, stability, and overall properties of the complex.

In an octahedral complex, the central metal ion is typically surrounded by six ligand sites, which can be filled with different ligands, as illustrated in the exercise for the \[\mathrm{Ni}(\mathrm{H}_2 \mathrm{O})_3(\mathrm{OH})_2 \mathrm{Cl}\] complex. An understanding of these arrangements is crucial when considering the activity of an enzyme's active site, the efficacy of a metal-based drug, or the outcome of a catalytic reaction.

The exercise demonstrates that with the same set of ligands, different structures, or isomers, can be formed based on which ligands are placed in the axial or equatorial positions. Knowledge of ligand arrangement assists chemists in synthesizing desired compounds with specific properties by manipulating the ligand environment around the metal center. It's a fundamental concept that enables chemists to harness the potential for creating advanced materials and therapeutics.