Coordination Compound Notes [ENDORSED]
Posted: Mon Dec 03, 2018 2:32 pm
Hi everyone! My name is Ronald, and I am one of your UAs this quarter. Several students in my office hours seemed to be struggling with coordination compounds and naming them, so I've attached my notes/tips, which I hope will help. If there's anything I'm missing, feel free to let me know! I can answer any questions for you if you reply to this post, so ask away if you have any!
Tips:
1. Know the ligands and the charges provided in this link: https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf. As you can see on the worksheet, Dr. Lavelle will accept either column (I find the first column with the * easier to remember, but either will be fine) -> "We use *. We will accept both."
2. Coordination number refers to the number of bonds made to the metal ion, not necessarily the number of ligands that bind to metal ion
3. Oxidation number => In simple ions, the oxidation number of the atom is the charge on the ion. For example, Na+, K+, and H+ all have oxidation numbers of +1.
4. Polydentate ligands: ligands that have multiple lone pair sites that can donate lone pairs to form coordinate covalent bonds with the metal ion
- Ex. Ethylenediamine has two nitrogens that have lone pairs that can be donated to form coordinate covalent bonds with the metal ion => because it has two sites it can use to form these bonds, it's known as a bidentate ligand
Naming:
1. To name a coordination compound, whether the complex ion is a cation or anion, always name the cation before the anion.
2. For naming the complex ion, name the ligands first (with prefixes if more than 1 ligand), in alphabetical order, then the metal atom or ion. Note: The metal atom or ion is written before the ligands in the chemical formula.
3. Anionic ligands like Cl end in "-o"
-ide => -o (Ex. chloride to chloro)
-ate => -ato (Ex. sulfate to sulfato)
-ite => -ito (Ex. nitrite to nitrito)
4. Greek prefixes indicate the number of each type of ligand in the complex ion
- Use di-, tri-, and tetra- for multiple monodentate ligands
- Use bis-, tris-, tetrakis- for multiple polydentate ligands (or if the ligand has a prefix in it already like ethylenediamine)
5. Don't forget to include the roman numerals to indicate the oxidation state of the metal ion! (ex. cobalt(III) ion)
6. For naming of coordination compounds with overall charge:
- If overall complex has a positive charge, metal is same name as element
*Ex. Co in a complex cation is called cobalt, and Pt is called platinum (Fe would just be iron)
- If overall complex has a negative charge, metal ends with the suffix "-ate"
*Ex. Co in a complex anion is called cobaltate, and Pt is called platinate (Fe would be ferrate)
7. Include "ion" in naming ONLY if the complex is by itself and not bound to something else, while the coordination complex has an overall charge
- Ex. [Cr(NH3)3(H2O)3]Cl3 would be triamminetriaquachromium(III) chloride
VS.
- Ex. [Cr(NH3)3(H2O)3] with a +3 overall would be triamminetriaquachromium(III) ion
Additional Notes:
1. Chelating compounds are compounds that involve two or more separate coordinate covalent bonds between a polydentate ligand and a central metal ion.
2. Only use prefixes when you're naming ligands and there are multiple ligands (ex. [Pt(H2NCH2CH2NH2)2Cl2]Cl2 is named dichlorobis(ethylenediamine)platinum(IV) chloride...if you look at the chlorides, we include "dichloro" when there are two chlorides attached to the platinum ion, and we include "chloride" like we do in MgCl2 (magnesium chloride), even though there are two chlorines.
Best,
Ronald
Tips:
1. Know the ligands and the charges provided in this link: https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf. As you can see on the worksheet, Dr. Lavelle will accept either column (I find the first column with the * easier to remember, but either will be fine) -> "We use *. We will accept both."
2. Coordination number refers to the number of bonds made to the metal ion, not necessarily the number of ligands that bind to metal ion
3. Oxidation number => In simple ions, the oxidation number of the atom is the charge on the ion. For example, Na+, K+, and H+ all have oxidation numbers of +1.
4. Polydentate ligands: ligands that have multiple lone pair sites that can donate lone pairs to form coordinate covalent bonds with the metal ion
- Ex. Ethylenediamine has two nitrogens that have lone pairs that can be donated to form coordinate covalent bonds with the metal ion => because it has two sites it can use to form these bonds, it's known as a bidentate ligand
Naming:
1. To name a coordination compound, whether the complex ion is a cation or anion, always name the cation before the anion.
2. For naming the complex ion, name the ligands first (with prefixes if more than 1 ligand), in alphabetical order, then the metal atom or ion. Note: The metal atom or ion is written before the ligands in the chemical formula.
3. Anionic ligands like Cl end in "-o"
-ide => -o (Ex. chloride to chloro)
-ate => -ato (Ex. sulfate to sulfato)
-ite => -ito (Ex. nitrite to nitrito)
4. Greek prefixes indicate the number of each type of ligand in the complex ion
- Use di-, tri-, and tetra- for multiple monodentate ligands
- Use bis-, tris-, tetrakis- for multiple polydentate ligands (or if the ligand has a prefix in it already like ethylenediamine)
5. Don't forget to include the roman numerals to indicate the oxidation state of the metal ion! (ex. cobalt(III) ion)
6. For naming of coordination compounds with overall charge:
- If overall complex has a positive charge, metal is same name as element
*Ex. Co in a complex cation is called cobalt, and Pt is called platinum (Fe would just be iron)
- If overall complex has a negative charge, metal ends with the suffix "-ate"
*Ex. Co in a complex anion is called cobaltate, and Pt is called platinate (Fe would be ferrate)
7. Include "ion" in naming ONLY if the complex is by itself and not bound to something else, while the coordination complex has an overall charge
- Ex. [Cr(NH3)3(H2O)3]Cl3 would be triamminetriaquachromium(III) chloride
VS.
- Ex. [Cr(NH3)3(H2O)3] with a +3 overall would be triamminetriaquachromium(III) ion
Additional Notes:
1. Chelating compounds are compounds that involve two or more separate coordinate covalent bonds between a polydentate ligand and a central metal ion.
2. Only use prefixes when you're naming ligands and there are multiple ligands (ex. [Pt(H2NCH2CH2NH2)2Cl2]Cl2 is named dichlorobis(ethylenediamine)platinum(IV) chloride...if you look at the chlorides, we include "dichloro" when there are two chlorides attached to the platinum ion, and we include "chloride" like we do in MgCl2 (magnesium chloride), even though there are two chlorines.
Best,
Ronald