How can I prevent Molecule from adding hydrogens automatically?

Consider the following:

cacl = Molecule[{Atom["Ca"], Atom["Cl"]}, {Bond[{1, 2}, "Single"]}];
MoleculeValue[cacl, "CanonicalSMILES"]
(* Cl[CaH] *)


Notice the artificial insertion of the hydrogen atom to fill the valency of the calcium atom. I understand that this behaviour is mentioned in the official documentation:

"Hydrogen atoms may be omitted from the atom list if their presence can be inferred from the valence and bonding of the atoms present."

But is there a way to suppress this default behaviour? I want the SMILES representation of the molecule above to be Cl[Ca+], not Cl[CaH].

• Unfortunately, there seems to be no way. I think this choice of default behaviour was a very short-sighted decision on the part of Wolfram Research. – Shredderroy Oct 8 at 16:34

I imagine it's because CaCl is not a valid compound. If you want CaCl+, you can do:

cacl = Molecule[{Atom["Ca+"], Atom["Cl"]}, {Bond[{1, 2}, "Single"]}]


MoleculeValue[cacl, "CanonicalSMILES"]


"Cl[Ca+]"

For CaCl2:

cacl2 = Molecule[{Atom["Ca"], Atom["Cl"], Atom["Cl"]}, {Bond[{1, 2}, "Single"], Bond[{1, 3}, "Single"]}];
MoleculeValue[cacl2, "CanonicalSMILES"]


"Cl[Ca]Cl"