In View > Properties > Bond Properties: The entry Rotatable for the
bonds in the molecule I can not change to Yes
At the moment, Avogadro directly uses Open Babel’s definitions of possibly rotatable bonds for automated conformer searching.
Several people have legitimately asked about manually setting bonds for conformer searching. I have a basic interface in mind, but haven’t had a chance with a pile of papers and grants to write. If someone were interested, I could talk them through coding.
In short, something along these lines should come in the next few months, but is not yet possible.
Hope that helps,
Prof. Geoffrey Hutchison
Department of Chemistry
University of Pittsburgh
tel: (412) 648-0492