Question

Supply acceptable names for the following. (a) \(\left[\mathrm{Co}(\mathrm{OH})\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\left(\mathrm{NH}_{3}\right)\right]^{2+}\) (b) \(\left[\mathrm{Co}(\mathrm{ONO})_{3}\left(\mathrm{NH}_{3}\right)_{3}\right]\) (c) \(\left[\operatorname{Pt}\left(\mathrm{H}_{2} \mathrm{O}\right)_{4}\right]\left[\mathrm{PtCl}_{6}\right]\) (d) \(\left[\mathrm{Fe}(\mathrm{ox})_{2}\left(\mathrm{H}_{2} \mathrm{O}\right)_{2}\right]^{-}\) (e) \(\mathrm{Ag}_{2}\left[\mathrm{HgI}_{4}\right]\)

Short answer

The respective names of the compounds are: (a) Tetraaquahydroxidoamminecobalt(II) (b) Trinitrotriamminecobalt(III) (c) Tetrakisaquaplatinum(II) hexachloroplatinate(IV) (d) Diaquadioxalatoferrate(III) (e) Disilver tetraiodomercurate(II).

Step-by-step solution

Naming compound (a)

For the compound \( \left[\mathrm{Co}(\mathrm{OH})\left(\mathrm{H}_{2}\mathrm{O}\right)_{4}\left(\mathrm{NH}_{3}\right)\right]^{2+} \), the central metal ion is cobalt (Co). It has four waters (H2O), one ammonia (NH3), and one hydroxide (OH-) as ligands. The name will be Tetraaquahydroxidoamminecobalt(II).

Naming compound (b)

For the compound \( \left[\mathrm{Co}(\mathrm{ONO})_{3}\left(\mathrm{NH}_{3}\right)_{3}\right] \), the central metal ion is cobalt (Co), with three ammonia and three nitro groups as ligands. The name will be Trinitrotriamminecobalt(III).

Naming compound (c)

For the compound \( \left[\operatorname{Pt}\left(\mathrm{H}_{2}\mathrm{O}\right)_{4}\right]\left[\mathrm{PtCl}_{6}\right] \), it is a complex salt with two complex ions. The cation is tetrakis(aqua)platinum(II), the anion is hexachloroplatinate(IV). So, the name will be Tetrakisaquaplatinum(II) hexachloroplatinate(IV).

Naming compound (d)

For the compound \( \left[\mathrm{Fe}(\mathrm{ox})_{2}\left(\mathrm{H}_{2}\mathrm{O}\right)_{2}\right]^- \), the central metal ion is iron (Fe), with two oxalate and two water ligands. The name should be Diaquadioxalatoferrate(III).

Naming compound (e)

For the compound \( \mathrm{Ag}_{2}\left[\mathrm{HgI}_{4}\right] \), the anion is tetraiodomercurate(II). We know that silver (Ag) is always mono positive, so the formula is based on 2 silver ions to balance the charge of the tetraiodomercurate(II) ion. Therefore, the name is Disilver tetraiodomercurate(II).

Key concepts

Coordination Compounds

Coordination compounds, also known as complex compounds, play a vital role in inorganic chemistry. They consist of a central metal atom or ion surrounded by molecules or ions called ligands. These ligands can be atoms, ions, or molecules that donate a pair of electrons to the metal, forming coordinate covalent bonds.

Ligands are not just simple bystanders; they define the properties of the coordination compound such as color, magnetic behavior, and reactivity. For instance, the color of the compounds in crystal field theory is explained by the d-d transition of electrons affected by the ligands surrounding the metal.

Correctly naming coordination compounds requires adherence to specific rules set by the International Union of Pure and Applied Chemistry (IUPAC). These rules ensure systematic naming, which helps in predicting the composition of the compound as well as understanding its structure. For example, ligands are named first, in alphabetical order, before the metal ion. The number of each type of ligand is indicated by prefixes like 'di-' for two, 'tri-' for three, and so on. The oxidation state of the metal is then enclosed in parentheses.

Inorganic Chemistry

Inorganic chemistry deals with the properties and behaviors of inorganic compounds, which include metals, minerals, and organometallic compounds, but excludes organic compounds that contain carbon-hydrogen bonds. It is a diverse field that covers a wide range of subjects from industrial applications like catalysts and semiconductors to biological systems like enzymes and hemoglobin.

In the context of this exercise, the focus is on understanding coordination chemistry, which is a cornerstone of inorganic chemistry. Coordination compounds are ubiquitous in nature and technology, influencing areas such as biochemistry with metalloproteins and industry with catalysts in the Haber process for ammonia synthesis. They exhibit unique chemical and physical characteristics that stem from the metal-ligand interactions.

Understanding the nomenclature in inorganic chemistry is essential for academic and real-world applications, as it provides a clear and unambiguous method to refer to chemical species. This allows chemists to communicate effectively and adhere to standardized practices in the scientific community.

Transition Metal Complexes

Transition metal complexes, a subgroup of coordination compounds, have a transition metal as their central metal ion or atom. These metals are characterized by having d orbitals that can be occupied by electrons, contributing to the formation of transition metal complexes with varied coordination numbers, geometries, and electronic configurations.

Transition metal ions have unique ability to exchange electrons with their ligands, contributing to properties such as variable oxidation states, magnetic character, and the ability to serve as good catalysts. In the provided examples, cobalt (Co), platinum (Pt), iron (Fe), and mercury (Hg) are transition metals that exhibit these characteristics in their complexes.

The naming process highlights the nature and number of ligands, the metal ion, and its oxidation state, as observed in the series of step-by-step solutions. For instance, in compound (a), 'tetraaquahydroxidoamminecobalt(II),' the prefixes 'tetra-' and 'hydroxido-' indicate four water and one hydroxide ligands, respectively, 'ammine' signifies an ammonia ligand, and 'cobalt(II)' indicates the oxidation state of cobalt. Understanding the naming conventions is crucial for identifying the structure and function of transition metal complexes in disciplines such as catalysis, material science, and medicine.