IDEA-AI4S/ChemO huggingface dataset:
IChO-2025_3 (111 points)

At 829.8 m, Dubai's Burj Khalifa is the world's tallest structure. To simplify construction, many floors were made from similar pieces. Some artificial "molecular skyscrapers" can be made through coordination chemistry of just two pieces: metal ions and organic ligands.

In these 3D structures, every vertex contains a square planar Pd(II) ion coordinated to four pyridine ligands. Along each edge is a bent organic ligand consisting of two pyridines linked together.

The angle between the two N->Pd bonds from the same ligand controls which structure forms. Larger angles give larger structures. Where free rotation around a bond is possible, the ligand adopts a conformation to form a structure with the smallest possible angle.


Answer:
IChO-2025_3.1 (6 points)


context: Each ligand (A, B, and C) can adopt a specific minimum N->Pd angle when coordinating to Pd(II). Possible angle options are: 0°, 30°, 45°, 60°, 90°, 120°, 135°, and 180°. Choose the smallest achievable angle for each ligand.
ligands: name: A
smiles: c1(C#Cc2ccncc2)ccncc1
name: B
smiles: C1(C2=CC(C3=CC=NC=C3)=CC=C2)=CC=NC=C1
name: C
smiles: C1(C2=CC=CC(C3=CC=CC(C4=CC=NC=C4)=C3)=C2)=CC(C5=CC=NC=C5)=CC=C1
options: 0°
30°
45°
60°
90°
120°
135°
180°
requirement: Select one angle value from the list above for each ligand (A, B, and C) that represents its smallest achievable N->Pd angle.

Answer:
context: A: 180°
B: 120°
C: 0°
grading: notes: 6 points total (2 points for each correct ligand–angle pair). No points awarded if more than one angle is selected for any ligand.
IChO-2025_3.2 (4 points)


context: Using '<', rank ligands D, E, and F from smallest to largest angle between the N->Pd bonds that they could form.
ligands: name: D
smiles: C1(C2=CC=C(S2)C3=CC=NC=C3)=CC=NC=C1
name: E
smiles: C1(C2=CC=C([Se]2)C3=CC=NC=C3)=CC=NC=C1
name: F
smiles: C1(C2=CC=C(O2)C3=CC=NC=C3)=CC=NC=C1
requirement: Output format example: D < E < F.

Answer:
text: F < D < E
grading: notes: 4 points total. 2 points awarded if the exact reverse order (E < D < F) is given.
One series of structures can be modelled as polyhedra with tetracoordinated  \mathrm{Pd(II)}  ions at the vertices. All structures have eight triangular faces  (F_{3}) , with various numbers of square faces  (F_{4}).

The triangular and square faces can be placed onto a square grid, where the relative position of two nearest triangles is described with integer coordinates  h  and  k .  Q  is then given by the equation:
Q = h^{2} + k^{2}

Part of the grid for a structure with  h = 2  and  k = 4  is shown below.
Q = h^{2} + k^{2} = 20

The smallest possible structure in this series is an octahedron, where  Q = 1 , and  (h, k) = (0, 1)  or  (1, 0) . It has six vertices, eight triangular faces, and 12 edges. Nearest triangles are a move of one face in one direction apart.
Q = h^{2} + k^{2} = 1

The second smallest structure is a cuboctahedron, where  Q = 2 . Nearest triangles are a move of one face in each direction apart.


Answer:
IChO-2025_3.3 (4 points)


context: Complete the column in the table for Q = 2, describing the number of vertices (V), number of edges (E), the total number of faces (F), and the number of square faces (F4).
requirement: All structures follow these geometric relationships:
1. V - E + F = 2
 2. V = 6Q
 3. F-V = 2
table: headers: Q = 1
Q = 2
rows: (h, k)
(0, 1) or (1, 0)
(1, 1)
V
6
E
12
F
8
F3
8
8
F4
0

Answer:
context: Values for the structure with Q = 2 (cuboctahedron).
table: headers: Parameter
Q = 2 Value
rows: (h, k)
(1, 1)
V
12
E
24
F
14
F3
8
F4
6
grading: notes: 4 points total (1 point for each correct value). No credit if numbers are placed in the wrong rows.
IChO-2025_3.4 (5 points)


context: Complete the table for the third smallest structure where Q = 4.
requirement: Fill in (h,k), V, E, F, and F4 when Q=4 with F3=8.
table: headers: Q
(h,k)
V
E
F
F3
F4
rows: 4
8

Answer:
context: Values for the third smallest structure (Q = 4).
table: headers: Parameter
Q = 4 Value
rows: (h, k)
(0, 2) or (2, 0)
V
24
E
48
F
26
F3
8
F4
18
grading: notes: 5 points total (1 point each). No credit if numbers are placed in wrong rows.
IChO-2025_3.6 (20 points)


context: Unlike symmetrical ligand L, chiral ligand M lacks symmetry and exists as a pair of R and S enantiomers. Lantern isomers are categorized by ligand chirality composition: (i) all the same (RRRR or SSSS), (ii) one different (RRRS or SSSR), (iii) cis-RRSS, and (iv) trans-RSRS; and by head–tail orientation: (1) HHHH, (2) HHHT, (3) cis-HHTT, (4) trans-HTHT. In any one combination, all possible isomers are either chiral or achiral.
ligand_M: smiles_R: [H][C@]1(C(C2=CC=CN=C2)=NN3)C(CCC1)=C3C4=CN=CC=C4
smiles_S: [H][C@@]1(C(C2=CC=CN=C2)=NN3)C(CCC1)=C3C4=CN=CC=C4
table: row_labels: i (RRRR/SSSS)
ii (RRRS/SSSR)
iii (cis-RRSS)
iv (trans-RSRS)
col_labels: 1 (HHHH)
2 (HHHT)
3 (cis-HHTT)
4 (trans-HTHT)
requirement: Complete the table by writing "C" for chiral and "A" for achiral in each applicable cell.

Answer:
context: Correct chiral/achiral assignments for each combination.
table: row_labels: i (RRRR/SSSS)
ii (RRRS/SSSR)
iii (cis-RRSS)
iv (trans-RSRS)
col_labels: 1 (HHHH)
2 (HHHT)
3 (cis-HHTT)
4 (trans-HTHT)
cells: C
C
C
C
C
C
C
C
A
C
A
C
A
C
A
A
grading: notes: Award points for each correct cell; deduct points for each incorrect cell down to a minimum of zero. No penalty for empty cells.
per_cell_points: 1.25
deduction_per_incorrect_cell: 1.25
min_score: 0
IChO-2025_3.7 (32 points)


context: Complete the table with the number of possible isomers for each combination of ligand chirality pattern (i–iv) and head–tail orientation (1–4). Each cell corresponds to one structural category. Enter the total number of distinct isomers in each case.
ligand_M: smiles_R: [H][C@]1(C(C2=CC=CN=C2)=NN3)C(CCC1)=C3C4=CN=CC=C4
smiles_S: [H][C@@]1(C(C2=CC=CN=C2)=NN3)C(CCC1)=C3C4=CN=CC=C4
table: row_labels: i (RRRR/SSSS)
ii (RRRS/SSSR)
iii (cis-RRSS)
iv (trans-RSRS)
col_labels: 1 (HHHH)
2 (HHHT)
3 (cis-HHTT)
4 (trans-HTHT)
cells: prefilled: no
value: 2
prefilled: yes
prefilled: no
prefilled: no
prefilled: no
prefilled: no
value: 4
prefilled: yes
prefilled: no
prefilled: no
prefilled: no
prefilled: no
prefilled: no
prefilled: no
prefilled: no
prefilled: no
prefilled: no
requirement: Write the total number of possible isomers for each combination. Cells that are already filled do not need to be answered. No partial credit for swapped rows/columns. No error carried forward from previous part.

Answer:
context: Correct number of isomers for each combination.
table: row_labels: i (RRRR/SSSS)
ii (RRRS/SSSR)
iii (cis-RRSS)
iv (trans-RSRS)
col_labels: 1 (HHHH)
2 (HHHT)
3 (cis-HHTT)
4 (trans-HTHT)
cells: 2
2
2
2
2
8
4
2
1
4
3
2
1
2
1
1
grading: notes: Each correct number earns the points shown; prefilled cells are not graded. No credit for incorrect or misplaced values; no alternative arrangements accepted; no carry-forward credit.
total_points: 32
per_cell_points: 1
1
1
1
2
4
4
2
2
4
4
2
2
2
2
3