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Questions and Answers
What is the term for additional bonding species that bond with a metal cation?
What is the term for additional bonding species that bond with a metal cation?
Which type of ligands typically results in the most stable coordination complexes?
Which type of ligands typically results in the most stable coordination complexes?
What characteristic of ligands allows them to form coordinate covalent bonds with metal ions?
What characteristic of ligands allows them to form coordinate covalent bonds with metal ions?
When polydentate ligands form a complex with a metal ion, what do the resulting structures commonly refer to?
When polydentate ligands form a complex with a metal ion, what do the resulting structures commonly refer to?
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What is the most common range of total atoms that makes chelates more stable?
What is the most common range of total atoms that makes chelates more stable?
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What purpose do sequestering agents serve in chemical applications?
What purpose do sequestering agents serve in chemical applications?
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Which of the following types of ligands only has one position capable of coordinating with a metal?
Which of the following types of ligands only has one position capable of coordinating with a metal?
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What is NOT a property of ligands as mentioned?
What is NOT a property of ligands as mentioned?
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Which heavy metal poisoning is primarily treated with calcium disodium edetate?
Which heavy metal poisoning is primarily treated with calcium disodium edetate?
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What is the pH range of an aqueous solution of calcium disodium edetate?
What is the pH range of an aqueous solution of calcium disodium edetate?
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What is a significant side effect of the disodium calcium form of edetate?
What is a significant side effect of the disodium calcium form of edetate?
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What route of administration is typically used for calcium disodium edetate?
What route of administration is typically used for calcium disodium edetate?
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Which of the following metals is not treated by calcium disodium edetate?
Which of the following metals is not treated by calcium disodium edetate?
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What is the main use for disodium edetate?
What is the main use for disodium edetate?
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What characteristic does the compound dimercaprol (BAL) possess?
What characteristic does the compound dimercaprol (BAL) possess?
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Which of the following statements about chelating agents is true?
Which of the following statements about chelating agents is true?
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What type of hybridization occurs when Cr(III) complexes with six CN- ligands in the formation of [Cr(CN)6]-3?
What type of hybridization occurs when Cr(III) complexes with six CN- ligands in the formation of [Cr(CN)6]-3?
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Which orbital remains empty when a d3 Cr(III) ion complexes with six cyanato groups?
Which orbital remains empty when a d3 Cr(III) ion complexes with six cyanato groups?
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What characteristic of the magnetic moment (MM) indicates the number of unpaired electrons in a complex?
What characteristic of the magnetic moment (MM) indicates the number of unpaired electrons in a complex?
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How does the replacement of water with cyanato anions affect the magnetic moment of an Fe(III) complex?
How does the replacement of water with cyanato anions affect the magnetic moment of an Fe(III) complex?
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What role do chelating agents play in analytical chemistry?
What role do chelating agents play in analytical chemistry?
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Which chelating agent is found in Benedict's solution for the identification of reducing substances?
Which chelating agent is found in Benedict's solution for the identification of reducing substances?
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In drug therapy, chelating agents are primarily used for which purpose?
In drug therapy, chelating agents are primarily used for which purpose?
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What change in electronic configuration occurs in metal ions with four or more d electrons when complexing?
What change in electronic configuration occurs in metal ions with four or more d electrons when complexing?
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What is the usual route of administration for Dimercaprol?
What is the usual route of administration for Dimercaprol?
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Which heavy metals are contraindicated for treatment with Dimercaprol?
Which heavy metals are contraindicated for treatment with Dimercaprol?
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What is the primary medical use of Penicillamine?
What is the primary medical use of Penicillamine?
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Which statement accurately describes Penicillamine?
Which statement accurately describes Penicillamine?
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What is the solubility characteristic of Deferoxamine Mesylate?
What is the solubility characteristic of Deferoxamine Mesylate?
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Why is urine alkalinization recommended during treatment with Dimercaprol?
Why is urine alkalinization recommended during treatment with Dimercaprol?
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What distinguishes Penicillamine from other chelating agents discussed?
What distinguishes Penicillamine from other chelating agents discussed?
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The effective neutralizing mechanism of Dimercaprol primarily involves:
The effective neutralizing mechanism of Dimercaprol primarily involves:
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Study Notes
Coordination Compounds and Complexation
- Cations can bond with additional anions or neutral molecules after fulfilling their initial valence requirements
- These additional bonding species are called ligands
- Ligands bond directly to the metal cation, following a maximum coordination number
- The maximum coordination number represents the maximum number of ligands a metal ion can accommodate; it's a property of the metal and its charge.
- Coordination numbers for various metal ions are presented in a table.
Properties of Ligands
- Ligands are typically anions or neutral molecules, not neutral atoms
- Ligands possess at least one nonbonded electron pair, used to form a coordinate covalent bond with the metal ion
- More stable complexes form with anionic or molecular ligands from Groups VA, VIA, or VIIA
- The stability order of ligands often parallels their basicity (Lewis base)
- Ligands can be classified based on the number of positions they can coordinate with a metal (e.g., monodentate, bidentate).
Some Common Polydentate Ligands
- Tables list several examples of polydentate ligands (e.g. Ethylenediamine, Glycinate, Oxalate).
Chelate Formation
- Polydentate ligands form ring structures called chelates when complexing a metal ion
- More stable chelates generally contain 5, 6, or 7 atoms in the ring
- Four and eight-membered rings are typically unstable
Complexes and Chelating Agents
- Complexation is used in analytical chemistry, enabling metal ion concentration determination by titration with complexing agents
- Chelating agents can solubilize metals, stabilizing their oxidation state
- Examples include Benedict's and Fehling's solutions (containing chelated copper(II) ions)
- Chelating agents are used as preservatives for preparations that might decompose due to trace metal contaminants (especially those containing hydrogen peroxide).
Bonding in Complexes
- (n-1)d, ns, and np orbitals often hybridize into six bonding orbitals, oriented along the ligand axes.
- This hybridization, often d2sp3, is equivalent when six ligands are equivalent.
- If a metal ion has four or more d electrons, the configuration changes during complexation, as can be measured by magnetic moment (MM).
Specific Chelating Agents
- Calcium Disodium Edetate (EDTA): Used to treat lead poisoning and other heavy metal poisonings; poorly absorbed from the gastrointestinal tract, administered intravenously. It has an affinity for calcium, and it forms stable water-soluble octahedral complexes with ferric ions.
- Dimercaprol (BAL): Used in arsenic, mercury, or gold poisoning. Poorly absorbed from the gastrointestinal tract and administered intramuscularly. Requires alkalinization of urine
- Penicillamine: Used in the treatment of Wilson's disease (copper buildup) and gold dermatitis. Administrated orally.
- Deferoxamine Mesylate: Used to treat acute iron toxicity. Administered intravenously; poorly absorbed from gastrointestinal tract
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Description
Test your knowledge on coordination compounds and the role of ligands in complexation. This quiz covers key concepts such as coordination numbers, bonding properties, and stability of complexes. Perfect for chemistry students looking to reinforce their understanding!
