>
> If I'm not mistaken, these two SMILES should represent the same molecule,
but OB thinks they're different:
c1ncccc1
c1[n]cccc1
According to the SMILES spec, putting the nitrogen in brackets only says
that its charge is zero and H-count is zero, which are the defaults when
the nitrogen is written as "n".
But OpenBabel thinks they're different. Note the "M RAD" line in the
second one.
$ echo "c1ncccc1" | babel -i smi -o sdf
OpenBabel05241215472D
6 6 0 0 0 0 0 0 0 0999 V2000
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 N 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
1 6 1 0 0 0 0
1 2 2 0 0 0 0
2 3 1 0 0 0 0
3 4 2 0 0 0 0
4 5 1 0 0 0 0
5 6 2 0 0 0 0
M END
$$$$
[carbon:cj] ~/tmp $ echo "c1[n]cccc1" | babel -i smi -o sdf
OpenBabel05241215472D
6 6 0 0 0 0 0 0 0 0999 V2000
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 N 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
0.0000 0.0000 0.0000 C 0 0 0 0 0 0 0 0 0 0 0 0
1 6 1 0 0 0 0
1 2 2 0 0 0 0
2 3 1 0 0 0 0
3 4 2 0 0 0 0
4 5 1 0 0 0 0
5 6 2 0 0 0 0
M RAD 1 2 2
M END
$$$$
This causes the SMILES writer to generate two different SMILES for this
molecule, one with [n] and one with a bare "n".
Is my analysis correct? Any idea where to begin looking to fix this?
Thanks,
Craig
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