(Bromomethyl)dibromoindium(III), Br2InCH2Br, reacts with tetraethylammonium bromide, 1,4-dioxane (diox), or tetrahydrofuran (thf) to produce addition compounds of the general formula Br2In(L) n CH2Br (L = diox, thf, n = 2; L = Br-, n = 1) in which the ligand is directly attached to the indium atom. The crystal structure of the ionic derivative [(C2H5)4N][Br3InCH2Br] has been solved by X-ray diffraction methods:  cell constants a = 10.1710(1) Å, b = 10.1710(1) Å, and c = 35.1745(4) Å, space group P41212, V = 3638.78(7) Å3, Z = 8, R = 0.0519, R w = 0.0543 for 2374 independent reflections. Quantum mechanical calculations, by the PM3 method, on the parent molecule confirm the postulated strong intramolecular interaction between the bromomethylic bromine and the metal center. Complete intramolecular bromide transfer gives the tautomeric structure Br3Inδ-CH2 δ+. The calculations also satisfactorily predict the bond distances and angles in the Br3InCH2Br- anion. Preliminary investigations of the energetics and chemical properties of Br2In(diox)2CH2Br show that the molecule can decompose via elimination of methylene, which can be trapped by a suitable substrate (carboxylic acid, iodine), demonstrating the potential use of the compound as a methylene-transfer reagent.