The crude product is dissolved in 10.5 ml deaerated MeCN with a defined water content of 20 ppt. Two NS29 Schlenk tubes (Volume of 250 ml) are then charged with seven glass test tubes (100 x 10 mm). Under argon, the crude solution is filtered through a 45 µm pore size Nylon syringe filter into the test tubes, leading to 1.5 ml per test tube. Afterwards, 35 ml of diethyl ether are added to the Schlenk tube, in order to crystallize the product via vapor diffusion. After five days, large crops of dark red, rhombus-shaped platelets are obtained (140 mg, 0.075 mmol, 30 %).