TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation (disclosed): Preparation of (I) comprises:(A) reacting a ligand-containing compound of formula MB'(R1)3 with a ligand-containing compound of formula HER2 to form ligand-containing compound of formula (R1)2MB'ER2, and contacting ligand-containing compound of formula (R1)2MB'ER2 with a chalcogen-containing compound of formula MA(ER3) in the presence of 1 eq ligand-containing compound of formula HER4;(B) reacting ligand-containing compound of formula MB(R1)3 with ligand-containing compound of formula MA(ER3), ligand-containing compound of formula HER2, and ligand-containing compound of formula HER4;(C) reacting ligand-containing compound of formula (N(R1)2)MB'(R2)2 with ligand-containing compound of formula HER3 to form ligand-containing compound of formula (N(R1)2)MB(R2)(ER3), and contacting with ligand-containing compound of formula MA(ER4) in the presence of 1 eq ligand-containing compound of formula HER5;(D) reacting ligand-containing compound of formula R1MB'X2 with ligand-containing compound of formula MA(ER2), ligand-containing compound of formula R3ESi(CH3)3, and ligand-containing compound of formula R4ESi(CH3)3; or(E) charging ligand-containing compound of formula (R1)2MB'(ER2) and an equimolar amount of ligand-containing compound of formula MA(ER2) in a glovebox in an inert, anaerobic atmosphere, adding dry solvent via cannula on a Schlenk line, heating the mixture to dissolve or disperse the components, adding an equimolar amount of ligand-containing compound of formula HER2 under nitrogen gas, heating the mixture optionally for 12 hours at 30-120 degrees C, cooling the solution optionally for several hours at - 80-15 degrees C, and isolating a solid or crystalline product.Preferred Component: The compound (I) is crystalline, and is a liquid at 25 degrees C. The compound is a dimer of formula (MA-(ER1)(ER2)(ER3)MB'R4)2. The compound is of formula (MA1 -(ER1)(ER2)(ER3)MB'R4)(MA2-(ER1)(ER2)(ER3)MB'R4). The ink is a solution or suspension of the compound (I) in an organic carrier. The ink further comprises a surfactant, a dispersant, an emulsifier, an anti-foaming agent, a dryer, a filler, a resin binder, a thickener, a viscosity modifier, an anti-oxidant, a flow agent, a plasticizer, a conductivity agent, a crystallization promoter, an extender, a film conditioner, an adhesion promoter, or a dye. The ink further comprises an additional indium-containing compound, an additional gallium-containing compound, a molybdenum-containing compound, a conducting polymer, copper metal, indium metal, gallium metal, zinc metal, an alkali metal, an alkali metal salt, an alkaline earth metal salt, a sodium chalcogenate, a calcium chalcogenate, cadmium sulfide, cadmium selenide, cadmium telluride, indium sulfide, indium selenide, indium telluride, gallium sulfide, gallium selenide, gallium telluride, zinc sulfide, zinc selenide, zinc telluride, copper sulfide, copper selenide, copper telluride, molybdenum sulfide, molybdenum selenide, and/or molybdenum telluride. SPECIFIC COMPOUNDS - 189 Compounds (I) are specifically claimed, e.g. Cu-(St'Bu)3Ini'Pr, Cu-(St'Bu)3Inn'Bu, Cu-(Set'Bu)3Inn'Bu, Cu-(St'Bu)3Int'Bu, Cu-(Set'Bu)3Gat'Bu.    EXAMPLE - A molecular precursor of formula Cu-(St'Bu)3Ini'Pr was synthesized by:    (A) charging 100 mL Schlenk tube with (g) iPr2In(St'Bu) (1.68) and Cu(St'Bu) (0.93) in an inert atmosphere glovebox;    (B) adding 20 mL dry toluene;    (C) heating the mixture until it became homogeneous;    (D) adding 0.7 mL HSt'Bu, and keeping under static nitrogen gas;    (E) heating for 12-14 hours at 60 degrees C with stirring;    (F) filtering while warm, and allowing crystals to form at room temperature;    (G) cooling at - 60 degrees C for 16 hours to yield yellow crystalline solid (1.4) with 47% yield.