Missing chemistry to (potentially) cover post-release-1

[davidlmobley]

Here's some chemistry covered by MMFF94 and GAFF/GAFF2 which we do not currently cover, and which is not currently represented in our datasets:

• [#8]~[#35]: O-Br single bonds are present in GAFF2 but not present in our current datasets. We could port in a placeholder value from GAFF2, but there are no molecules with this chemistry in our current datasets.
• [#7X3]~[#7X3]~([#8])~[#8]: Nitroamines
• [#6:1]~[#6:2]=[#15:3]~[#6:4]: C=P double bond (potentially with adjacent singles)

I will likely update this issue with more such cases.

Compounds containing this chemistry are present in eMolecules, but not in our current datasets.