Weak interactions between furfuryl and equatorial dioxime ligand in furfuryl(O2)Co(dmgH)2Py: NMR, X-ray and DFT calculations

The crystal and molecular structure of furfuryl(O2)Co(dmgH)2Py (1) has been determined by X-ray diffraction analysis. In the molecular structure of 1, the furfuryl ring oxygen is pointing inwards and is very close to one of the dmgH (Me) (2.625 Å). It shows unusual C–H···O weak interaction which must be responsible for the observed 1:3 ratio of dmgH methyl protons in NMR spectrum. Also, theoretical calculations using DFT have been performed on 1 for the Co–O and CH2–C(furfuryl) bond rotation. Conformational energy diagrams derived from theoretical calculations also indicate that in most stable conformer the furfuryl ring oxygen is very close to one of the dmgH (Me) groups.