Final answer:
The copper(I) ion or the cuprous ion (Cu+) will not react with a diazonium ion.
Step-by-step explanation:
The copper(I) ion or the cuprous ion (Cu+) will not react with a diazonium ion. Copper(I) halides include CuF, CuCl, CuBr, and CuI. When the diazonium ion (ArN2+) reacts with a copper(I) halide, it forms an arenediazonium copper(I) halide complex. However, the bromide ion (Br-) in CuBr can react with the diazonium ion, so CuBr will not be the correct answer.