Synthesis of H3 Ph L. All manipulations were performed inside a glovebox. A 500 mL round-bottom flask equipped with a stir bar was charged with Ph Int1 (27 g, 31 mmol, 1 equiv) and MeCN (300 mL). The flask was cooled in a liquid nitrogen-chilled cold well. Solid O-(2,4-dinitrophenyl)-hydroxylamine (22 g, 110 mmol, 3.5 equiv) was added in small portions with stirring. The mixture was allowed to warm up to room temperature, resulting in the formation of a deep red solution with a yellow precipitate. The 31 P NMR of this red solution shows a single peak at 35 ppm, which corresponds to the chemical shift of the [Ph3PNH2] + moiety (Figure ). After stirring for 3 hours at room temperature, the flask was cooled again in a liquid nitrogen-chilled cold well. Neat Me3SiCl (35 g, 322 mmol, 10 equiv) that had been previously purified by short-path vacuum distillation was added in small portions with stirring. The mixture was allowed to warm up to room temperature, resulting in the formation of a yellow suspension. The mixture was further stirred at room temperature for 24 hours before the yellow precipitate was collected in a fritted funnel. The yellow solid was repeatedly washed with MeCN until the filtrate was colorless, subsequently washed with Et2O, and thoroughly dried under reduced pressure. This insoluble yellow solid is assigned to the tris-phosphiniminium intermediate Ph Int2 with chloride counter-anions and was used without further purification. A 500 mL round-bottom flask equipped with a stir bar was charged with Ph Int2 (25 g, 25 mmol, 1 equiv) and THF (300 mL). The flask was cooled in a liquid nitrogen-chilled cold well. Solid NaO t Bu (7.14 g, 74 mmol, 3 equiv) was added in small portions with stirring. The mixture was allowed to warm up to room temperature, resulting in the formation of a slightly beige solution over a brown precipitate. The mixture was further stirred at room temperature for 18 hours before being filtered through a pad of Celite. All volatiles were thoroughly removed from the filtrate. The beige residue was with Et2O and stirred until a fine suspension was obtained. The solid was collected in a fritted funnel, and washed with Et2O repeatedly. The collected solid was washed with small amounts of cold THF to remove colored impurities. The white solid was washed with pentane and dried under reduced pressure. H3 Ph L was obtained as a white solid (20 g, 70 % from Ph Int1). H NMR (400 MHz, CDCl3): 7.66 -7.53 (dd, J = 11.9, 7.2 Hz, 12 H), 7.42 -7.28 (m, 21 H), 7.19 (t, J = 7.7 Hz, 3H), 7.05 -6.93 (m, 6 H), 6.60 (s, 1.50 (bs, 3H, NH) ppm. P NMR (162 MHz, CDCl3): 20.6 ppm. Synthesis of 1. A 20 mL scintillation vial equipped with a stir bar was charged with H3 Ph L (200 mg, 0.221 mmol, 1 equiv) and THF (10 mL). A freshly prepared solution of (THF)Co[N(SiMe2)2]2 (149.7 mg, 0.332 mmol, 1.5 equiv) in THF (10 mL) was added dropwise with stirring. The mixture was stirred at room temperature for 12 hours, resulting in the formation of a dark green solution. All volatiles were removed under reduced pressure. The green residue was repeatedly washed with pentane, followed by diethyl ether. The remaining solid was extracted with toluene and filtered through a pad of Celite. All volatiles were removed from the filtrate under reduced pressure. The green residue was redissolved with C6H6, and Et2O was carefully layered on top of the C6H6 solution to induce crystallization. Compound 2 was isolated as large, dark green, block-shaped crystals (137.7 mg, 63 %). Synthesis of 2. Method 1: A 20 mL scintillation vial equipped with a stir bar was charged with H3 Ph L (118 mg, 0.13 mmol, 1 equiv) and THF (10 mL). A freshly prepared solution of (THF)Co[N(SiMe2)2]2 (59 mg, 0.13 mmol, 1 equiv) in THF (5 mL) was added dropwise with stirring. The mixture was stirred at room temperature for 2 hours, resulting in the formation of a light green solution. A freshly prepared THF solution of C2Cl6 (32 mg, 0.13 mmol, 1 equiv) that had been previously purified by sublimation was added quickly at once, resulting in the formation of a deep red solution. The mixture was stirred at room temperature for 18 hours. A small amount of an insoluble brown precipitate was removed by filtration. All volatiles were removed from the filtrate under reduced pressure. The red residue was repeatedly washed with pentane. The remaining solid was extracted with a 9:1 Et2O:C6H6 mixture and filtered through a pad of Celite. All volatiles were removed from the filtrate under reduced pressure. The red residue was redissolved in C6H6, and pentane was carefully layered on top of the C6H6 solution to induce crystallization. Complex 2 was isolated as thin red plates (85 mg, 68 %). Large crystals suitable for single crystal Xray diffraction were obtained by slow vapor diffusion of Et2O into a solution of 2 in THF. Method 2: A 20 mL scintillation vial equipped with a stir bar was charged with 1 (40 mg, 0.020 mmol, 1 equiv) and C6H6 (10 mL). A freshly prepared solution of C2Cl6 (4.8 mg, 0.020 mmol, 1 equiv) in C6H6 (5 mL) was added at once with stirring. The mixture was stirred at room temperature for 3 hours, resulting in a dark red solution. All volatiles were removed under reduced pressure. The red residue was repeatedly washed with pentane, followed by diethyl ether. The remaining solid was extracted with toluene and filtered through a pad of Celite. All volatiles were removed from the filtrate under reduced pressure. The 1 H NMR (Figure ) matches an authentic sample of 2 (25.4 mg, 66 %).