Plasmas containing Chlorine (Cl2) and Boron trichloride (BCl3) are used in the patterning of interconnects during integrated circuit manufacturing. Optimization of the plasma uniformity in the reactor is important for the purpose of accurate pattern transfer across the entire wafer. Optimization, however, requires understanding of the influence of the reactor variables (power, pressure, and geometry) on the plasma chemistry. Simulation can aid in providing understanding of metal etch reactors by providing insight into the relative importance of chemical path ways and their dependence on reactor external variables. We have developed a chemical model for an Ar, BCL3, Cl2 discharge. Comparisons with experimental measurements inside a commercial reactor demonstrate good agreement with plasma density and electron temperature. The model also captures the plasma density distribution across the reactor and the dissociation characteristics with respect to pressure. Results below 10 mTorr suggest that parent negative ions may play an important role in the discharge.