Question

What is the best name for

K[Cr(NH3)2Cl2SO4]
A. potassium kiamminedichlorosulfatochromium(III).
B. potassium diamminedichlorosulfatochromate (II).
C. potassium diamminedichlorochromatium (III) sulfate.
D. potassium diamminedichlorochromate(II) sulfate.
E. potassium diamminedichlorosulfatochromate (III).

Answer 1

Answer: E. potassium diamminedichlorosulfatochromate (III).

Step-by-step explanation

Rules for naming of the coordination compounds :

a) The ligand named first then metal.

b) The charge of metal indicated with the Roman numerals and enclosed in the parenthesis after metal name.

c) The ligands are named in alphabetical order before the metal ion.

d) Ligands that include a numerical prefix in the name use the prefixes bis for 2, tris for 3, or tetrakis for 4 to indicate their number.

e) If the complex ion is an anion, we drop the ending of the metal name and add –ate.

In the given coordination compound, Cr is the chromium metal,
`NH_3` ,
`Cl` and
`SO_4` are the ligands named as ammine, chloro and sulphato.

The charge on
`[Cr(NH_3)_2Cl_2SO_4]` is -1. Ammine is a neutral ligand, chloro is having an oxidation state of -1 and sulphato is having an oxidation state of -2.

x+2(0)+2(-1)+1(-2)=-1

x=+3

Hence, the IUPAC name of
`K[Cr(NH_3)_2Cl_2SO_4]` is potassium diaaminedichlorosulphato chromate (III)