The bond between chlorine and bromine in $\mathrm{BrCl}$ is

The bond between chlorine and bromine in $\mathrm{BrCl}$ is polar with negative end on Cl. The bond is polar due to electronegativity difference between bromine and chlorine. Since chlorine is more electronegative than bromine, the bond pairs of electrons will be more attracted towards chlorine. So the negative end will be on chlorine.