Match Each Coordination Compound In Column I With An Appropriate Pair Of Characteristics From Column II, Using The Provided Codes And Atomic Numbers (Ti = 22, Cr = 24, Co = 27, Pt = 78; En = H2NCH2CH2NH2).

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Coordination compounds, also known as complex compounds, play a pivotal role in various fields, including chemistry, biology, and materials science. These compounds consist of a central metal atom or ion bonded to a surrounding array of molecules or ions, called ligands. The nature of the metal ion and ligands significantly influences the properties of the coordination compound, including its color, magnetic behavior, and reactivity. Understanding these characteristics is crucial for designing and utilizing coordination compounds in diverse applications.

Matching Coordination Compounds with Their Characteristics

To delve deeper into the fascinating world of coordination compounds, let's analyze a scenario where we match specific coordination compounds with their unique characteristics. This exercise will not only enhance our understanding of coordination chemistry principles but also demonstrate how different factors contribute to the overall properties of these compounds.

Understanding Coordination Compounds

Before we begin matching, it's essential to grasp the fundamental concepts of coordination chemistry. A coordination compound comprises a central metal ion and its surrounding ligands. The metal ion acts as a Lewis acid, accepting electron pairs from the ligands, which act as Lewis bases. This interaction forms coordinate covalent bonds, holding the complex together. The number of ligands attached to the metal ion is known as the coordination number, and it determines the geometry of the complex.

Ligands can be neutral molecules or ions, and they can be classified based on the number of donor atoms they possess. Monodentate ligands have one donor atom, while polydentate ligands have multiple donor atoms. Ethylenediamine (en), denoted as H2NCH2CH2NH2, is a bidentate ligand, meaning it has two nitrogen atoms that can donate electron pairs to the metal ion. The nature of the ligands significantly affects the properties of the coordination compound.

Factors Influencing Coordination Compound Properties

Several factors influence the characteristics of coordination compounds, including:

  • Metal ion: The identity of the metal ion plays a crucial role in determining the properties of the complex. Different metal ions have varying tendencies to form complexes, and their electronic configurations influence the color and magnetic behavior of the compound.
  • Ligands: The nature of the ligands attached to the metal ion significantly impacts the complex's properties. Ligands can affect the crystal field splitting, which in turn influences the color and magnetic properties. Strong-field ligands cause a larger splitting, leading to low-spin complexes, while weak-field ligands result in high-spin complexes.
  • Coordination number: The number of ligands attached to the metal ion determines the geometry of the complex. Different geometries, such as tetrahedral, square planar, and octahedral, have distinct electronic and magnetic properties.
  • Oxidation state: The oxidation state of the metal ion influences the electronic configuration and, consequently, the properties of the complex.

Matching Coordination Compounds and Characteristics

Now, let's consider the task of matching coordination compounds with their characteristics. We'll analyze each compound, considering the factors mentioned above, and identify the appropriate properties.

Column I: Coordination Compounds

  1. [Ti(en)(NH3)4]2+
  2. [Cr(NH3)6]3+
  3. [Co(en)2Cl2]+
  4. [PtCl4]2-

Column II: Characteristics

A. Paramagnetic B. Diamagnetic C. Exhibits geometric isomerism D. Exhibits optical isomerism

To solve this, we need to analyze each coordination compound individually and determine its characteristics based on the metal ion, ligands, coordination number, and oxidation state.

1. [Ti(en)(NH3)4]2+

  • Metal ion: Titanium (Ti) in a +2 oxidation state.
  • Ligands: Ethylenediamine (en) is a bidentate ligand, and ammonia (NH3) is a monodentate ligand.
  • Coordination number: The coordination number of Ti is 6 (2 from en + 4 from NH3).
  • Electronic configuration: Ti2+ has a d2 electronic configuration.

Considering these factors, [Ti(en)(NH3)4]2+ is a paramagnetic complex because of the presence of unpaired electrons in the d orbitals. It does not exhibit geometric or optical isomerism due to its structure.

2. [Cr(NH3)6]3+

  • Metal ion: Chromium (Cr) in a +3 oxidation state.
  • Ligands: Ammonia (NH3) is a monodentate ligand.
  • Coordination number: The coordination number of Cr is 6.
  • Electronic configuration: Cr3+ has a d3 electronic configuration.

[Cr(NH3)6]3+ is also a paramagnetic complex due to the unpaired electrons in the d orbitals. It does not exhibit geometric or optical isomerism because all the ligands are the same.

3. [Co(en)2Cl2]+

  • Metal ion: Cobalt (Co) in a +3 oxidation state.
  • Ligands: Ethylenediamine (en) is a bidentate ligand, and chloride (Cl-) is a monodentate ligand.
  • Coordination number: The coordination number of Co is 6 (4 from en + 2 from Cl).
  • Electronic configuration: Co3+ can be low-spin or high-spin depending on the ligand field strength.

[Co(en)2Cl2]+ can exhibit geometric isomerism (cis and trans isomers) and optical isomerism (cis isomer is chiral). This is because the two chloride ligands can be either on the same side (cis) or opposite sides (trans) of the cobalt ion. The cis isomer is chiral and can exist as enantiomers.

4. [PtCl4]2-

  • Metal ion: Platinum (Pt) in a +2 oxidation state.
  • Ligands: Chloride (Cl-) is a monodentate ligand.
  • Coordination number: The coordination number of Pt is 4.
  • Electronic configuration: Pt2+ has a d8 electronic configuration.

[PtCl4]2- is a diamagnetic complex due to the strong field ligands causing pairing of electrons in the d orbitals. It exhibits geometric isomerism (cis and trans isomers) because the four chloride ligands are arranged around the platinum ion in a square planar geometry. However, it does not exhibit optical isomerism.

Summarizing the Matches

Based on our analysis, we can match the coordination compounds with their characteristics as follows:

  1. [Ti(en)(NH3)4]2+ - A (Paramagnetic)
  2. [Cr(NH3)6]3+ - A (Paramagnetic)
  3. [Co(en)2Cl2]+ - C (Exhibits geometric isomerism) and D (Exhibits optical isomerism)
  4. [PtCl4]2- - B (Diamagnetic) and C (Exhibits geometric isomerism)

This matching exercise highlights the importance of considering various factors when determining the properties of coordination compounds. By understanding the nature of the metal ion, ligands, coordination number, and oxidation state, we can predict and explain the characteristics of these fascinating compounds.

Applications of Coordination Compounds

Coordination compounds have found widespread applications in various fields due to their diverse properties. Some notable applications include:

Catalysis

Coordination compounds serve as catalysts in numerous industrial processes. Transition metal complexes, in particular, exhibit excellent catalytic activity due to their ability to change oxidation states and coordinate with reactants. For instance, Wilkinson's catalyst, [RhCl(PPh3)3], is widely used in the hydrogenation of alkenes. Similarly, Ziegler-Natta catalysts, which are complexes of titanium or other transition metals, are employed in the polymerization of olefins.

Medicine

Coordination compounds have revolutionized the field of medicine, serving as therapeutic agents and diagnostic tools. Cisplatin, [PtCl2(NH3)2], is a well-known anticancer drug that inhibits DNA replication in cancer cells. Other platinum-based drugs, such as carboplatin and oxaliplatin, are also used in cancer treatment. Additionally, coordination compounds containing gadolinium are used as contrast agents in magnetic resonance imaging (MRI), enhancing the visibility of internal organs and tissues.

Pigments and Dyes

Coordination compounds are responsible for the vibrant colors of many pigments and dyes. Transition metal complexes often exhibit intense colors due to d-d electronic transitions. For example, Prussian blue, Fe4[Fe(CN)6]3, is a deep blue pigment widely used in paints and inks. Similarly, chlorophyll, a magnesium-containing coordination compound, is the green pigment responsible for photosynthesis in plants.

Analytical Chemistry

Coordination compounds play a crucial role in analytical chemistry, serving as reagents for qualitative and quantitative analysis. EDTA (ethylenediaminetetraacetic acid), a hexadentate ligand, forms stable complexes with many metal ions and is used in titrations to determine metal ion concentrations. Dimethylglyoxime (DMG) is a specific reagent for nickel ions, forming a red precipitate that can be used for gravimetric analysis.

Environmental Chemistry

Coordination compounds are employed in environmental chemistry for various purposes, including water treatment and pollution control. Metal complexes can be used to remove heavy metals from wastewater by forming insoluble precipitates. Additionally, coordination compounds can serve as catalysts for the degradation of pollutants, such as organic dyes and pesticides.

Conclusion

Coordination compounds are a fascinating class of chemical substances with diverse properties and applications. By understanding the factors that influence their characteristics, such as the metal ion, ligands, coordination number, and oxidation state, we can design and utilize these compounds in various fields. From catalysis and medicine to pigments and analytical chemistry, coordination compounds continue to play a vital role in advancing scientific knowledge and technological innovation. The ability to match coordination compounds with their properties is not just an academic exercise; it's a critical skill that underpins many real-world applications and future advancements in chemistry and related fields.