Coordination chemistry of Br2InCH2Br: Coordination at the metal center

(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)(4)N][Br3InCH2Br] has been solved by X-ray diffraction methods: cell constants a 10.1710(1) Angst rom, b = 10.1710(1) Angstrom, and c = 35.1745(4) Angstrom, space group P4(1 )2(1)2, V = 3638.78(7) Angstrom(3), Z = 8, R = 0.0519, R-w = 0.0543 for 237 4 independent reflections. Quantum mechanical calculations, by the PM3 meth od, on the parent molecule confirm the postulated strong intramolecular int eraction between the bromomethylic bromine and the metal center. Complete i ntramolecular bromide transfer gives the tautomeric structure Br3Indelta-CH 2delta+. The calculations also satisfactorily predict the bond distances an d angles in the Br3InCH2Br- anion. Preliminary investigations of the energe tics and chemical properties of Br2In(diox)(2)CH2Br show that the molecule can decompose via elimination of methylene, which can be trapped by a suita ble substrate (carboxylic acid, iodine), demonstrating the potential use of the compound as a methylene-transfer reagent.