%O This version is the author-accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions. %X Layered carbides are fascinating compounds due to their enormous structural and chemical diversity, as well as their potential to possess useful and tunable functional properties. Their preparation, however, is challenging and forces synthesis scientists to develop creative and innovative strategies to access high-quality materials. One unique compound among carbides is Moâ‚‚Gaâ‚‚C. Its structure is related to the large and steadily growing family of 211 MAX phases that crystallize in a hexagonal structure (space group P6₃/mmc) with alternating layers of edge-sharing M₆X octahedra and layers of the A-element. Moâ‚‚Gaâ‚‚C also crystallizes in the same space group, with the difference that the A-element layer is occupied by two A-elements, here Ga, that sit right on top of each other (hence named “221†compound). Here, we propose that the Ga content in this compound is variable between 2:2, 2:1, and 2: ≤1 (and 2:0) Mo/Ga ratios. We demonstrate that one Ga layer can be selectively removed from Moâ‚‚Gaâ‚‚C without jeopardizing the hexagonal P6₃/mmc structure. This is realized by chemical treatment of the 221 phase Moâ‚‚Gaâ‚‚C with a Lewis acid, leading to the “conventional†211 MAX phase Moâ‚‚GaC. Upon further reaction with CuClâ‚‚, more Ga is removed and replaced with Cu (instead of fully exfoliating into the Ga-free Moâ‚‚CTx MXene), leading to Moâ‚‚Gaâ‚â‚‹â‚“Cuâ‚“C still crystallizing with space group P6₃/mmc, however, with a significantly larger c-lattice parameter. Furthermore, 211 Moâ‚‚GaC can be reacted with Ga to recover the initial 221 Moâ‚‚Gaâ‚‚C. All three reaction pathways have not been reported previously and are supported by powder X-ray diffraction (PXRD), electron microscopy, X-ray spectroscopy, and density functional theory (DFT) calculations. %C United States %L discovery10194590 %J Inorganic Chemistry %I RSC %D 2024 %P 7725-7734 %N 17 %V 63 %A Carina Büchner %A Niels Kubitza %A Ali M Malik %A John Jamboretz %A Aysha A Riaz %A Yujiang Zhu %A Christoph Schlueter %A Martha R McCartney %A David J Smith %A Anna Regoutz %A Jochen Rohrer %A Christina S Birkel %T Chemical Conversions within the Mo–Ga–C System: Layered Solids with Variable Ga Content