JEE (Advanced) 2026, Paper 1, Chemistry, Section 3 — the answer is a numerical value: +4 if only the correct value is entered, 0 in all other cases.
Q.10 The total number of all possible isomers for the square planar complex with formula K[M(NCS)(NO2)(gly)] is ____.
(M = metal ion and gly = NH2CH2COO– )
One metal, four corners, three ligands. Press START EXPERIMENT — the whole investigation runs by itself: read the formula → find the donor atoms → count the linkage sets → seat the chelate → build every arrangement → fold by symmetry → the mirror test → audit the traps → answer.
Four corners, three ligands, two of them ambidentate. The question's complex is loaded — press START EXPERIMENT.
A seating is one way of putting the donor atoms on the four corners. Two seatings are the same isomer when a rotation of the square turns one into the other.
each step up is a seating no rotation of an earlier one can match
how many of the seatings turned out to be each isomer — the size of the square's symmetry
not yet examined
not yet examined
not yet examined
not yet examined
Nothing investigated yet.
Hold one molecule of the complex. Turn it, flip it over, hold it to a mirror — it never becomes a new isomer. Swap two ligands between corners, or change which atom a ligand binds through — now it does. Count how many different ones you can make.
Run the experiment — the solution opens with the answer.
The experiment has not finished yet. Press START and let it run to the end — or use Reveal anyway in the header if you are revising.
K⁺ is a counter-ion. The complex anion [M(NCS)(NO₂)(gly)]⁻ has M²⁺ and four donor atoms: one each from NCS⁻ and NO₂⁻, two from glycinate.
NCS⁻ binds through N or S; NO₂⁻ through N (nitro) or O (nitrito). The choices are independent.
Glycinate spans two cis corners (its N and O are different). The two other ligands fill the remaining corners: one of them trans to N, the other trans to O — or the other way round.
A square-planar complex lies in its own mirror plane, so its mirror image is itself.
The lab built all 16 seatings of each set (4 cis edges × 2 ways round × 2 ways to fill the other corners) and found that the 8 rotations of a square fold them into exactly 2.
Every isomer is flat, so it is superimposable on its mirror image: no optical isomers.
Adding instead of multiplying gives 6; doubling for mirror images gives 16; forgetting linkage isomerism gives 2; treating glycinate as symmetrical gives 4. On a tetrahedron the same ligands would also give 8 — but as 4 pairs of enantiomers, a different reason entirely.
For a student opening it for the first time. The whole investigation runs by itself after one press.
A square-planar complex with glycinate, thiocyanate and nitrite. How many different isomers can it have?
The question's complex is loaded — square planar, NCS⁻, NO₂⁻, glycinate. You do not need to change anything.
Try a tetrahedral metal, a symmetrical chelate or single-donor halides. The lab tells you honestly when a change takes you off the question. ↺ RESTORE QUESTION CONDITIONS puts everything back.
Press ▶ START EXPERIMENT. There is nothing else to click (about a minute; 2× makes it faster).
The ligands show their donor ends, the lab lists the linkage sets, seats the chelate, builds all 64 seatings one by one, folds them by symmetry and holds each isomer to a mirror.
When the audit is complete the lab says ✓ EXPERIMENT COMPLETE and reveals the count. Badges unlock on the way.
In the Isomer explorer turn, flip and swap until you have made every isomer yourself, then press SHOW ALL ISOMERS. Then read the Detailed solution.
Press ▶ REPLAY EXPERIMENT, or change a ligand and press ⚙ RUN WITH CUSTOM VALUES. CLASSROOM MODE enlarges everything for a projector.
| Exam | JEE Advanced 2026, Paper 1, Chemistry, Section 3, Q.10 |
|---|---|
| Chapter | Coordination Compounds |
| Topic | Isomerism in coordination compounds - linkage, geometrical and optical isomers of a square planar complex |
| Difficulty | Moderate |
| Answer | — run the experiment |