Binary and ternary carbides of alkali and alkaline-earth metals

Synthesis of β-Mg2C3: A Monoclinic High-Pressure Polymorph of Magnesium Sesquicarbide

“…The recent synthesis of Mg 2 C, 9 predicted 20 years before, 20 demonstrates the possibility for direct formation from the elements under high-pressure conditions (p > 15 GPa, T ∼ 1770 K). 21 Two factors contribute to this simultaneously: (1) HP increases the affinity between carbon and magnesium, and (2) HP stabilizes the sp 3 carbon state, covalent 22 as well as ionic, 9 allowing us to consider high pressure as a powerful tool to explore magnesium−carbon chemistry and to discover new compounds with unusual bonding states and properties. In the present Article we report the synthesis of monoclinic β-Mg 2 C 3 , a high-pressure polymorph of magnesium sesquicarbide, previously only known as an orthorhombic (α) phase.…”

Ternary Alkali Metal Transition Metal Acetylides

“…Only the synthesis of KAgC 2 was described [8] and also some ternary alkaline-earth metal transition metal carbides (e.g. Ca 4 Ni 3 C 5 [9] and see chapter 3.2 in [7])…”

Synthesis of Mg2C: A Magnesium Methanide

“…[10,11] The ambient-pressure chemistry of the Mg À C system was studied quite thoroughly in the past. [12] Magnesium forms an acetylide-type carbide, MgC 2 , [13] similar to all other alkalineearth metals. Mg also forms Mg 2 C 3 , [14] a derivative of propadiene (H 2 C = C = CH 2 ), which is unique for the alkalineearth metals and is one of only a handful of examples that contain the rare [C = C = C] 4À group.…”