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All the isomers of the square planar complex K[M(NCS)(NO2)(gly)]: linkage, geometrical and optical

A square-planar metal ion with glycinate, thiocyanate and nitrite. Press start and the lab does the rest: it reads the formula (K+ outside, M(II), four donor atoms), shows each ambidentate ligand bound through each of its ends, lists the 2 x 2 = 4 linkage sets, shows that the glycinate chelate can only span a cis edge, builds all 64 seatings of the donor atoms on the four corners one by one, folds them with the 8 rotations of a square into distinct isomers, holds every isomer up to a mirror, and audits two common wrong answers before revealing the count. No prediction stage - input, run, watch, result.

Sub-topics covered

• Ambidentate ligands and linkage isomerism
• Unsymmetrical bidentate (AB) chelating ligands
• Geometrical isomerism of square planar [M(AB)cd]
• Optical isomerism and mirror planes
• Counting isomers by symmetry

What it teaches

• K+ is a counter-ion; the complex anion [M(NCS)(NO2)(gly)]- has M(II) and four donor atoms: coordination number 4, square planar
• NCS- binds through N (thiocyanato-N) or S (thiocyanato-S); NO2- through N (nitro) or O (nitrito): 2 x 2 = 4 linkage sets
• Glycinate is an unsymmetrical N,O chelate that can only span two cis corners
• Square planar [M(AB)cd] has 2 geometrical isomers: c trans to A or c trans to B
• A square planar complex lies in its own mirror plane, so it has no optical isomers: total 4 x 2 = 8

Simulation ID

• ADV-2026-P1-CHE-Q10 · revision 1

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