What is the systematic name of [Co(en)₂(NH₃)CN]Cl₂.

• A. Amminocyanodiethylenediaminecobalt(II) chloride
• B. Amminecyanobisethylenediaminecobalt(II) chloride
• C. Amminocyanodi(ethylenediamine)cobalt(III) chloride
• D. Amminecyanobis(ethylenediamine)cobalt(III) chloride

Answer: (D)

Verified step by step guidance

1. Identify the central metal ion in the complex. Here, it is cobalt (Co).
2. Determine the oxidation state of the central metal ion. The complex is neutral overall, and the ligands are ethylenediamine (en), ammonia (NH3), and cyanide (CN). Ethylenediamine is a neutral ligand, ammonia is also neutral, and cyanide has a charge of -1. The chloride ions (Cl) outside the complex contribute a -2 charge. Therefore, the oxidation state of cobalt must be +3 to balance the charges.
3. List the ligands in alphabetical order, using their proper names: 'ammine' for NH3, 'cyano' for CN, and 'ethylenediamine' for en. Since there are two ethylenediamine ligands, use the prefix 'bis' to indicate this.
4. Combine the ligand names with the metal name and its oxidation state. The ligands are listed as 'ammine', 'cyano', and 'bis(ethylenediamine)', followed by the metal 'cobalt' with its oxidation state in Roman numerals, (III).
5. Add the counter ion name at the end. Since there are two chloride ions, the name ends with 'chloride'. Thus, the systematic name is 'Amminecyanobis(ethylenediamine)cobalt(III) chloride'.