Fig. 4: Dimerization of 1.

a Time-dependence of the 1H-NMR spectra of 1 at 30 °C measured in C2Cl4D2. Chemical equilibrium is attained after 34.4 h. b HPLC chromatogram of the equilibrated sample using a 5PBB HPLC column (I.D. 10 × 250 mm) at a flow rate of 4 mL/min with toluene as mobile phase. c The mass spectra of 1 and (1)2.