Spectrus: Reassigning NMR peaks after structure changes in Spectrus

Description
If a structure is modified after NMR assignments have been created (for example, adding/removing atoms, changing numbering), existing assignments may no longer match correctly. Spectrus allows reassignment, but care is needed to avoid mismatches.

Solution

1. If structural changes are minor (e.g., small corrections without changing atom count or numbering):
   • Make the edits and verify that atom numbers are unchanged.
   • Check assignments for consistency.
2. If structure changed alter atom numbering or new atoms introduced:
   • Consider saving a copy of the original record before major edits.
   • Update the structure.
   • Carefully review each assignment:
     • Use the assignment table and atom labels to realign peaks to the correct atoms.
   • Remove obsolete assignments and recreate them as necessary.
3. For larger structural changes:
   • It may be simpler to:
     • Clear all assignments using Edit > Clear.
     • Reassign peaks using the updated structure from scratch.
4. After reassignment:
   • Verify multiplet labels, integrations, and peak–atom links before generating reports.