Using C[Sn](C)(C)Cl, c1c[se]c(-c2ccc[se]2)c1 to produce C[Sn](C)(C)c1ccc(-c2ccc([Sn](C)(C)C)[se]2)[se]1, please predict the agent for this reaction in SMILES notation in \boxed{$SMILES1, SMILES2, ...} format.