Question

Select the grouping in which all statements are TRUE regarding the rules for naming complexes:

I. The ligands are named in alphabetical order after the metal ion.

II. The isomer (e.g.,cis‐ or trans‐) is included after the listing of the ligands of the complex.

III. The complex [Cr(en)3] 3+ would be named Δ‐ or Λ‐tris(ethylenediamine)chromium(III) depending on the arrangement of the en ligands and the rotation of polarized light.

IV. Cis‐diaminodichloroplatinum(II) and trans‐diaminodichloroplatinum(II) are possible names for Pt(NH3)2 Cl2.

V. The correct name for the complex [Tc(NMe3)6] 3+ is hexa(trimethylamine)technetium(III).

Answers:

A) III, IV and V

B) I, II, III, and IV

C) I, II, and V

D) III and IV

Answer 1

Following points are analysed while naming a complex compound.

I. The ligands are named in alphabetical order after the metal ion.

Ligands are named in alphabetical order before addressing metal ion forming coordination sphere. So first statement is wrong only.

II. The isomer (e.g.,cis‐ or trans‐) is included after the listing of the ligands of the complex.

This statement is also wrong as cis/trans is written in the beginning of the name or before listing the ligands in alphabetical order.

III. The complex [Cr(en)3] 3+ would be named Δ‐ or Λ‐tris(ethylenediamine)chromium(III) depending on the arrangement of the en ligands and the rotation of polarized light.

Yes. this is a correct statement. Handedness of the coordination complex for bidentate and tridentate ligand is decided based on arrangement of ligands or rotation of plane polarised light. Delta notation is used when chelating ligand describes a right handed helix.. It is lambda when it is left handed.

IV. Cis‐diaminodichloroplatinum(II) and trans‐diaminodichloroplatinum(II) are possible names for Pt(NH3)2 Cl2.

Yes both cis and trans isomer of Diamminedichloridoplatinum(II)(Correct naming as per recent IUPAC ammendments) have same molecular formula

V. The correct name for the complex [Tc(NMe3)6] 3+ is hexa(trimethylamine)technetium(III).

It is not correct name. Ligand already contains greek prefix 'tri' word so it has to be listed with prefix 'hexakis' instead of just hexa.

Answer

III and IV statements are correct.