AbstractA number of solvates having the general formula M(CH3CN)m(M′Br4)nis reported. In this formula M = Cu(I), or one of the divalent ions Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd; m is 4 or 6; M′ = Al, Fe, In, Tl; and n = 1 or 2.The compounds are prepared by bromide‐ion transfer reactions between MBr2(or CuBr) and M′Br3in anhydrous acetonitrile.Characterization and identification of these solvates were performed with the aid of chemical analyses, infrared spectra, ligand‐field spectra and X‐ray powder diagrams.The M′Br4−anions are demonstrated to be tetrahedrally co‐ordinated, whereas the M(CH3CN)62+cations are octahedrally co‐ordinated with nitrogen as the