4.1.4. Preparation of DIII (via Route C)

A solution of lithium bis(trimethylsilyl)amide etherate (4.7 g, 19.5 mmol) in toluene (200 mL) was added dropwise to a stirring tolyl solution (150 mL) of phthalonitrile (2.5 g; 19.5 mmol) and subsequently stirred overnight. Chlorotrimethylsilane (2.2 mL, 19.5 mmol) was added to the solution and refluxed for an additional 24 h. Lithium chloride was removed through hot filtration of the mixture in vacuo. The brown filtrate was passed through a column of silica and washed with DCM and EtOAc, respectively. The desired product was collected with a 25% MeOH in EtOAc solution (v/v). The solvent of the filtrate was removed in vacuo and the resulting brown solid was washed with ether, DCM, and EtOAc consecutively, resulting in a light orange solid. Yield 1.23 g (8.5 mmol, 44%). Samples were characterized spectroscopically and compared to references in literature [34]. 1H-NMR (δ, CD3CN, RT, 400 MHz): 7.76 (m, 2H), 7.59 (m, 2H).

#### 4.1.5. Preparation of Silicon Phthalocyanine Dichloride (via Route C)

Reaction was performed analogously to previously reported literature starting with 1 g of diiminoisoindoline (via Route C) [27]. Crude yield 0.54 g (0.9 mmol, 51%). Samples were characterized spectroscopically and compared to references in literature [33]. HR-MS (EI) for C32H16Cl2N8Si [M]<sup>+</sup>: Calcd, 610.0644; Found, 610.0637.
