Data type: Experimental spectroscopic measurements, Computer Simulation and Analysis Files are in txt, spc, par, opj, and m format Information on origin of the data: EPR spectroscopic measurements in spc and par formats EPR spectroscopic simulation and analyses in m format UV-vis and IR spectroscopic measurements and analyses; and polymer analyses in opj format Are the data generated (e.g. by a machine) or collected (e.g. by means of a survey)? EPR spectroscopic measurements were generated by ELEXYS 580 EPR spectrophotometer equipped with SHQ cavity and ER035 M NMR gaussmeter produced by Bruker. FT-IR spectroscopic measurements were generated by Vertex70 produced by Bruker equipped with an MCT detector. UV-Vis-NIR spectroscopic measurements were generated by Cary5000 spectrophotometer produced by Varian equipped with a reflectance sphere. If t Files in PARACAT_WP4_20201229_01_EPR folder includes EPR spectroscopic measurements and computer simulations/analyses, original data are in spc/par formats; files in m format were used to process the data of the same name and saved the results in txt format. Information on: specialized abbreviations: EPR – Electron Paramagnetic Resonance, GC – Gas Chromatography, GPC – Gel Permeation Chromatography definitions of variables: Magnetic field, Wavenumber, Pressure units of measurement: Gauss (G), milli Tesla (mT), cm-1, milli bar (mbar) abbreviations: IR/EPR/UV are data relate to measurements of IR/EPR/UV-Vis spectroscopy. abbreviation: CO/C2H4 are data relate to methods with CO/ethene dosage. abbreviation: polym is data relates to polymer analysis conducted by GC and GPC

The spc/par files can be opened on proprietary EPR softwares from Bruker or MatLab (version R2020a used by the authors) with EasySpin toolbox (version 6.0.0-dev.26 used by the authors) The simulation/analysis of EPR measurements can be opened and run on MatLab (version R2020a used by the authors) with EasySpin toolbox (version 6.0.0-dev.26 used by the authors) The opj files can be opened on Origin/OriginPro/Origin Viewer If it is not possible to make the code and software openly available on Zenodo: 1. MatLab can be purchased/downloaded from: https://www.mathworks.com/products/matlab.html 2. Origin/OriginPro/Origin Viewer can be purchased/downloaded from: https://www.originlab.com/ 3. EasySpin toolbox can be downloaded from: https://easyspin.org/