For the first time, COT was synthesized starting from diethyl oxalate and calcite.
Its Raman bands and synchrotron XRD were collected for the first time.
The vibrational assignment of the IR and Raman spectra are critically proposed.
Comparative analysis of the IR and Raman spectra of COM, COD and COT is performed.
Complex net of H-bonding interactions of COT is discussed.