Question

Draw two linkage isomers of \(\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{NO}_{2}\right)\right]^{2+}\)

Short answer

The two linkage isomers of \(\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{NO}_{2}\right)\right]^{2+}\) are the nitro isomer, with \(\mathrm{NO}_{2}\) bound through the nitrogen, and the nitrito isomer, with \(\mathrm{NO}_{2}\) bound through the oxygen.

Step-by-step solution

Understanding Linkage Isomerism

Linkage isomerism occurs when a ligand is capable of attaching to the central metal ion through two different atoms. In the complex ion \(\left[\mathrm{Mn}\left(\mathrm{NH}_{3}\right)_{5}\left(\mathrm{NO}_{2}\right)\right]^{2+}\), the ligand that can exhibit linkage isomerism is the nitrito group, \(\mathrm{NO}_{2}\), which can bind through the nitrogen (N) or through the oxygen (O) atom.

Drawing the First Isomer

The first isomer is when \(\mathrm{NO}_{2}\) acts as a ligand through the nitrogen atom, which is called the nitro configuration. Represent \(\mathrm{NO}_{2}\) with the nitrogen atom directly bonded to the \(\mathrm{Mn}\) ion.

Drawing the Second Isomer

The second isomer is when \(\mathrm{NO}_{2}\) acts as a ligand through one of the oxygen atoms, which is called the nitrito configuration. Draw the \(\mathrm{NO}_{2}\) group with one of the oxygen atoms directly bonded to the \(\mathrm{Mn}\) ion.

Key concepts

Coordination Chemistry

Coordination chemistry explores the fascinating world of coordination compounds, where central metal atoms or ions are surrounded by molecules or ions termed 'ligands'. These ligands are not just mere spectators; they play a crucial role in shaping the properties of the central atom, much like friends influencing your choice of attire for an event. Imagine a celebrity (the metal ion) at a fancy gala, wearing various accessories (ligands) that radiate their own unique style.

In essence, coordination compounds contain a coordinative bond formed between the electron-rich ligand and the electron-poor metal cation. The number of ligands attached to the central metal ion is known as the coordination number, and the geometrical arrangement of these ligands is referred to as the coordination geometry. Such compounds are responsible for many of the colors we see in materials and are essential in biological systems as well as industrial processes. Understanding the behavior of coordination compounds helps in the development of new materials, drugs, and catalysts.

Ligands in Coordination Complexes

Ligands are akin to characters in a play with the central metal ion as the protagonist. They bond to the metal ion to form coordination complexes, a union celebrated in the realm of coordination chemistry. Each ligand possesses 'donor atoms' with lone pairs of electrons eagerly awaiting to engage with a metal ion craving electron density.

However, not all ligands are cut from the same cloth; they vary in their denticity, that is, their ability to bind through one (monodentate), two (bidentate), or several (polydentate) donor atoms. The charm of these ligands lies in their versatility; some even have the innate ability to attach themselves to the metal ion via different atoms leading to a phenomenon called 'linkage isomerism'.

The two linkage isomers in the exercise above are akin to two different poses struck by the ligand 'nitrito'—in one, it connects through nitrogen, and in the other, it opts for oxygen, showcasing its dual nature. The bond type and site of attachment profoundly affect the personality of the complex, impacting properties like color, reactivity, and magnetic behavior.

Chemical Bonding

Chemical bonding is the glue that holds atoms together within molecules and compounds. It's like the cohesive force that forms a team from individual players. Within coordination complexes, the metal-ligand bonding occurs through the magic of electron sharing or donation, where ligands offer their electron pairs to the electron-hungry metal centers.

The personality of a bond can fluctuate between the extremes of pure ionic character, where electrons are donated, to pure covalent nature, where there's an even sharing. The bond in coordination complexes tends to meander closer to the covalent side, as the ligands share their lone pairs with the metal ion, resulting in a coordinative covalent bond.

Linkage isomerism provides an impeccable demonstration of chemical bonding's flexibility: the same ligand, nitrito, can showcase different bonding sites. This slight adjustment in bonding can lead to significant changes in the physical and chemical properties of the complex, underscoring that sometimes, a switch in perspective (or bonding site) can entirely change the outcome.