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Ch.21 - Transition Elements and Coordination Chemistry
All textbooksMcMurry 8th EditionCh.21 - Transition Elements and Coordination ChemistryProblem 71
Chapter 21, Problem 71

Draw the structure of the platinum ethylenediamine complex [Pt(en)2]2+. Describe the coordination geometry, and identify any chelate rings. What are the coordination number and the oxidation state of the platinum?

Verified step by step guidance
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Step 1: Understand the components of the complex. The complex [Pt(en)2]2+ consists of a platinum ion (Pt) and two ethylenediamine (en) ligands. Ethylenediamine is a bidentate ligand, meaning it can form two bonds with the metal center.
Step 2: Draw the structure of the complex. Start by placing the platinum ion at the center. Each ethylenediamine ligand will form two coordinate covalent bonds with the platinum, creating a chelate ring. Arrange the ligands symmetrically around the platinum.
Step 3: Determine the coordination geometry. With two bidentate ligands, the coordination number of platinum is 4. The most common geometry for a coordination number of 4 is square planar, which is typical for platinum(II) complexes.
Step 4: Identify the chelate rings. Each ethylenediamine ligand forms a five-membered chelate ring with the platinum ion. These rings are formed by the two nitrogen atoms of the ethylenediamine and the platinum ion.
Step 5: Determine the oxidation state of platinum. The complex has an overall charge of 2+. Ethylenediamine is a neutral ligand, so the charge on the platinum must be +2 to balance the overall charge of the complex. Therefore, the oxidation state of platinum is +2.

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Coordination Complexes

Coordination complexes consist of a central metal atom or ion bonded to surrounding molecules or ions called ligands. In this case, platinum (Pt) is the central metal, and ethylenediamine (en) acts as a bidentate ligand, meaning it can form two bonds with the metal. Understanding the nature of these complexes is essential for analyzing their structure and properties.
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Coordination Geometry

Coordination geometry refers to the spatial arrangement of ligands around the central metal atom in a coordination complex. For the complex [Pt(en)2]2+, the geometry is typically octahedral due to the presence of two bidentate ligands, which occupy six coordination sites. This geometry influences the complex's stability and reactivity.
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Oxidation State and Coordination Number

The oxidation state of a metal in a complex indicates its charge, which affects its reactivity and bonding. In [Pt(en)2]2+, platinum has an oxidation state of +2. The coordination number, which is the total number of ligand bonds to the metal, is 6 in this case, as each ethylenediamine ligand forms two bonds, contributing to the overall coordination.
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Related Practice
Textbook Question

What is the formula, including the charge, for each of the following complexes?

(a) An iridium(III) complex with three ammonia and three chloride ligands

(b) A chromium(III) complex with two water and two oxalate ligands

(c) A platinum(IV) complex with two ethylenediamine and two thiocyanate ligands

Textbook Question

What is the formula, including the charge, for each of the following complexes?

(a) An iron(III) complex with six water ligands

(b) A nickel(II) complex with two ethylenediamine and two bromide ligands

(c) A platinum(II) complex with two chloride and two ammonia ligands

Textbook Question

Draw the structure of the iron oxalate complex [Fe(C2O4)3]3-. Describe the coordination geometry, and identify any chelate rings. What are the coordination number and the oxidation number of the iron?

Textbook Question

Draw the structure of the following complexes. What are the oxidation state, coordination number, and coordination geometry of the metal in each?

(a) Na[Au(CN)2]

Textbook Question

Draw the structure of the following complexes. What are the oxidation state, coordination number, and coordination geometry of the metal in each?

(b) [Cr(NH3)2(C2O4)2]NO2

Textbook Question

Draw the structure of the following complexes. What are the oxidation state, coordination number, and coordination geometry of the metal in each?

(a) Pt(en)2