Your SMILES string would appear to have a neutral 4-co-ordinate nitrogen atom in it, which doesn't exist in real molecules.  4-co-ordinate nitrogen atoms have a positive charge, eg [N+] in a SMILES string.
I want to get the molecules from the SMILES using rdkit in python. The SMILES I used was downloaded from the drugbank.
However, when I using the function Chem.MolFromSmiles, some SMILES would report but some wouldn't:
Explicit valence for atom # 0 N, 4, is greater than permitted.
I found some explanation about this problem: it is because the SMILES generated a invalid molecule that doesn't exist in real world.  But I am not a chemistry student.... So anyone know how to fix this?
Problems encountered when using RDKIT to convert SMILES to mol