Acetonitrile is a weak base and is not frequently used as a ligand in coordination chemistry investigations. Due to the nature of this ligand, it was thought that cobalt(II) and nickel(II) complexes with acetonitrile ligands would be unstable and that the solid state of these complexes probably would not exist. Basolo1 indicated that solid salts separated from solution easiest for combinations of either small-small or large-large cations and anions, preferably with systems having the same but opposite charges on the counter ions. The driving force for the large cation-large anion combination to form solid is the small hydration energy of the ions. When Co (II) and Ni(II) are completely solvated by acetonitrile, they form large cations; these large cations could be effectively stabilized by large anions such as tetrachlorometallates or tetrabromometallates. The purpose of this study is fourfold. The first is to synthesize the complexes by using large anions, BCl4 and BBr4. The second is to compare results with similar systems. The third is to make theoretical investigations of the molecular model assuming distortion and the last is to analyze the complexes experimentally