The reaction of $\mathrm{SbCl}_{3}$, with 3 equivalents of EtMgBr yields compound X . Two equivalents of $\mathrm{SbI}_{3}$ react with one equivalent of X to give Y . In the solid state, Y has a 1 D -polymeric structure in which each Sb is in a square pyramidal environment. Compounds X and Y respectively, are
(a)$\mathrm{SbEt}_{3}$, and $\left[\mathrm{Sb}(\mathrm{Et}) \mathrm{I}_{2}\right]_{\mathrm{n}}$
(c)$\mathrm{SbEt}_{3}$, and $\left[\mathrm{SbEt}_{2} \mathrm{Br}_{2}\right]_{\mathrm{n}}$
(b)$\mathrm{Sb}\left(\mathrm{Et}_{2}\right) \mathrm{Cl}$ and $[\mathrm{Sb}(\mathrm{Et}) \mathrm{Cl}]_{\mathrm{n}}$
(d)$\mathrm{Sb}(\mathrm{Et}) \mathrm{Br}_{2}$ and $[\mathrm{SbEt}(\mathrm{I})(\mathrm{Br})]_{\mathrm{n}}$