Textbook Question
Identify the oxidation state of the metal in each of the following compounds.
(a) Co(NH3)3(NO2)3
(b) [Ag(NH3)2]NO3
(c) K3[Cr(C2O4)2Cl2]
(d) Cs[CuCl2]
Ch.21 - Transition Elements and Coordination Chemistry
Chapter 21, Problem 68
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
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Identify the oxidation state of the central metal in each complex. For (a) iridium(III) indicates an oxidation state of +3 for iridium. For (b) chromium(III) indicates an oxidation state of +3 for chromium. For (c) platinum(IV) indicates an oxidation state of +4 for platinum.
Determine the charge contributed by each ligand. Ammonia (NH3) is a neutral ligand, contributing 0 charge. Chloride (Cl-) is an anionic ligand, contributing -1 charge per ligand. Water (H2O) is a neutral ligand. Oxalate (C2O4^2-) is an anionic ligand, contributing -2 charge per ligand. Ethylenediamine (en) is a neutral ligand. Thiocyanate (SCN-) can bind through either sulfur or nitrogen and is an anionic ligand, contributing -1 charge per ligand.
Calculate the total charge of the ligands for each complex. For (a), three chloride ligands contribute a total charge of -3. For (b), two oxalate ligands contribute a total charge of -4. For (c), two thiocyanate ligands contribute a total charge of -2.
Combine the charges of the central metal and the ligands to determine the overall charge of the complex. For (a), the total charge is +3 (from iridium) + (-3 from ligands) = 0. For (b), the total charge is +3 (from chromium) + (-4 from ligands) = -1. For (c), the total charge is +4 (from platinum) + (-2 from ligands) = +2.
Write the formula for each complex, including the charge. For (a), the formula is [Ir(NH3)3Cl3]. For (b), the formula is [Cr(H2O)2(C2O4)2]^-1. For (c), the formula is [Pt(en)2(SCN)2]^+2.
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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 known as ligands. The nature of these ligands, whether neutral or charged, influences the overall charge of the complex. Understanding how ligands coordinate to the metal is essential for determining the formula and charge of the complex.
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00:43
Coordination Complexes Example
Oxidation States
The oxidation state of a metal in a coordination complex indicates its charge and is crucial for writing the correct formula. For example, iridium(III) indicates that iridium has a +3 charge. Knowing the oxidation states of the metal and the charges of the ligands allows for accurate calculation of the overall charge of the complex.
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02:42Oxidation Numbers
Ligand Types and Charges
Ligands can be classified as neutral or charged, and their individual charges must be considered when determining the overall charge of the complex. For instance, ammonia is a neutral ligand, while chloride carries a -1 charge. Understanding the types of ligands and their respective charges is essential for constructing the correct chemical formula for the complexes.
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02:38Ligand Types
Related Practice
Textbook Question
Identify the oxidation state of the metal in each of the following compounds.
(a) (NH4)3[RhCl6]
(b) [Cr(NH3)4(SCN)2]Br
(c) [Cu(en)2]SO4
(d) Na2[Mn(EDTA)]
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?