You are watching: B) tris(ethylenediamine)cobalt(iii) bromide

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Author: Kit Mao department of 2175forals.com, Washington university St. Louis, MO 63130

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A coordination facility is a substance in which a steel atom or ion accepts electrons from (and thus associates with) a group of neutral molecules or anions referred to as ligands. A facility can it is in an anion, a cation ion, or a neutral molecule. Coordination compounds space neutral substances (i.e. Uncharged) in i beg your pardon at least one ion is present as a complex. You will certainly learn more about coordination compound in the lab lectures because that experiment 5 in this course.

The coordination link are called in the following way.

A. Once naming coordination compounds, always name the cation prior to the anion. This ascendancy holds nevertheless of whether the facility ion is the cation or the anion. (This is as with naming one ionic compound.)

B. In specify name the complex ion:

1. Surname the ligands first, in alphabetical order, and then surname the main metal. Note: In the 2175forals.com formula the central metal is written before the ligands.

2. The names of some typical ligands are noted in Table 1.

Anionic ligands finish in "-o." because that anions that end in "-ide"(e.g. Chloride, hydroxide), "-ate" (e.g. Sulfate, nitrate), and "-ite" (e.g. Nirite), change the endings together follows:

-ide → -o; e.g., chloride → chloro and hydroxide → hydroxo

-ate → -ato; e.g., sulfate → sulfato and also nitrate → nitrato

-ite → -ito; e.g., nitrite → nitrito

for neutral ligands, the common name of the molecule is supplied (e.g. H2NCH2CH2NH 2 (ethylenediamine)). Essential exceptions: water is dubbed "aqua", ammonia is dubbed "ammine", carbon monoxide is called "carbonyl", and also the N2 and also O2 molecules are called "dinitrogen" and "dioxygen".

Table 1. Names of Some common Ligands

Anionic Ligands surname Neutral Ligands names
Br- bromo NH3 ammine
F- fluoro H2O aqua
O2- oxo NO Nitrosyl
OH- hydroxo CO Carbonyl
CN- cyano O2 dioxygen
C2O42- oxalato N2 dinitrogen
CO32- carbonato C5H5N pyridine
CH3COO- acetato H2NCH2CH2NH2 ethylenediamine

3. The Greek prefixes di-, tri-, tetra-, etc. Are used to designate the variety of each type of ligand in the complicated ion. If the ligand currently contains a Greek prefix (e.g. Ethylenediamine) or if that is a polydentate ligand (i.e. That can attach at an ext than one coordination site), the prefixes bis-, tris-, tetrakis-, and pentakis- are used instead. (See examples 3 and also 4.) The numerical prefixes are provided in Table 2.

Table 2. Number Prefixes

Number Prefix Number Prefix Number Prefix
1 mono 5 penta (pentakis) 9 nona (ennea)
2 di (bis) 6 hexa (hexakis) 10 deca
3 tri (tris) 7 hepta 11 undeca
4 tetra (tetrakis) 8 octa 12 dodeca

4. After naming the ligands, surname the central metal. If the facility ion is a cation, the steel is named same together the element. Because that example, Co in a complex cation is called cobalt and Pt is referred to as platinum. (See examples 1-4.) If the complex ion is an anion, the surname of the steel ends v the suffix -ate. (See examples 5 and 6.) for example, Co in a complicated anion is referred to as cobaltate and also Pt is dubbed platinate. For part metals, the Latin names are supplied in the facility anions (e.g. Fe is called ferrate and not ironate).

Table 3: surname of metals in Anionic Complexes

name of steel surname in one Anionic complex
steel Ferrate
Copper Cuprate
lead Plumbate
silver Argentate
yellow Aurate
tin Stannate

5. Following the name of the metal, the oxidation state that the metal in the facility is offered as a Roman numeral in parentheses.

C. To name a neutral complex molecule, monitor the rules of specify name a facility cation. Remember: surname the (possibly complex) cation prior to the (possibly complex) anion. See instances 7 and also 8.

For historic reasons, some coordination compound are dubbed by their usual names. Because that example: Fe(CN)63- and Fe(CN) 64- are called ferricyanide and also ferrocyanide respectively, and also Fe(CO)5 is called iron carbonyl.


The facility ion is found inside the parentheses. In this case, the complex ion is a cation. The ammine ligands are named an initial because alphabetically, "ammine" comes prior to "aqua." The compound is electrically neutral and also thus has actually an in its entirety charge that zero. Because there room three chlorides associated with one complex ion and each chloride has actually a –1 charge, the fee on the complex ion must be +3. native the charge on the complex ion and the charge on the ligands, we can calculate the oxidation variety of the metal. In this example, all the ligands room neutral molecules. Therefore, the oxidation number of chromium must be the very same as the fee of the complex ion, +3.
The complex ion is a cation, and the counter anions space the 3 bromides. The charge of the complicated ion have to be +3 since it is connected with 3 bromides. The NH3 molecules space neutral while the chloride tote a - 1 charge. Therefore, the oxidation number of platinum must be +4.

3. Cl2

Answer: dichlorobis(ethylenediamine)platinum(IV) chloride


The sulfate has a fee of –2 and is the counter anion in this molecule. because it takes 3 sulfates to bond through two facility cations, the fee on each facility cation should be +3. because ethylenediamine is a neutral molecule, the oxidation variety of cobalt in the complicated ion must be +3. Again, remember the you never need to indicate the variety of cations and anions in the name of one ionic compound.

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Potassium is the cation, and the complicated ion is the anion. because there room 4 K+ linked with the facility ion (each K+ having actually a +1 charge), the charge on the facility ion should be - 4. because each ligand carries –1 charge, the oxidation variety of Fe must be +2. The common name the this compound is potassium ferrocyanide.