Question

Write the formula of the coordination compound pentaamminecarbonatocobalt(III) iodide. Enclose the coordination complex in square brackets, even if there are no counter ions. Do not enclose a ligand in parentheses if it appears only once. Enter water as H2O. Use any abbreviation given in blue below, and enclose it in parentheses if there is more than one.

Answer 1

The formula of the coordination compound pentaamminecarbonatocobalt(III) iodide is [Co(NH3)5(CO3)]I, which features a cobalt center coordinated to five ammonia ligands and one bidentate carbonate ligand, followed by an iodide counter ion.

Step-by-step explanation:

The formula for the coordination compound called pentaamminecarbonatocobalt(III) iodide can be written by following the naming conventions for coordination compounds. First, we name the cationic part of the compound, which is the cobalt ion with its attached ligands, followed by the anion.

In this case, the cobalt ion has a +3 charge and is surrounded by five ammonia (NH3) ligands and one carbonate ion (CO3) which acts as a bidentate ligand. The overall coordination sphere is then followed by the counter ion, iodide (I-). To write the formula, start with the cobalt ion, add the ligands in alphabetical order, and then the counter ion. The formula is [Co(NH3)5(CO3)]I.

Since carbonate is a bidentate ligand, it counts as one ligand in this context despite coordinating through two donor atoms. The ammonia ligands are neutral, and the cobalt (III) indicates the oxidation state of the cobalt is +3. With all components considered, the proper formula is enclosed within square brackets for the coordination complex followed by the counter ion.

Answer 2

[Co(NH3)5CO3]I3

Step-by-step explanation:

The naming of coordination compounds follows certain rules specified by IUPAC. Usually, the name of the complex makes it quite easy to deduce its structure.

"Pentaamine" means that there are five NH3 ligands as shown in the structure. The ligand carbonato is CO3^2-. It has no prefix attached to it in the IUPAC name of the complex hence there is only one carbonato ligand present(recall that the complex has a coordination number of six). I did not enclose it within parenthesis as required in the question.

Lastly the III that appeared after the metal name "cobalt" shows its oxidation state. The iodide counter ions must then be 3 in number in order to satisfy this primary valency of the metal hence the inclusion of I3 in the structure of the complex.