Input interpretation
tetraphenylporphine anion | structure diagram
Result
Draw the Lewis structure of tetraphenylporphine anion. Start by drawing the overall structure of the molecule, ignoring potential double and triple bonds: Count the total valence electrons of the carbon (n_C, val = 4), hydrogen (n_H, val = 1), and nitrogen (n_N, val = 5) atoms, including the net charge: 44 n_C, val + 28 n_H, val + 4 n_N, val - n_charge = 226 Calculate the number of electrons needed to completely fill the valence shells for carbon (n_C, full = 8), hydrogen (n_H, full = 2), and nitrogen (n_N, full = 8): 44 n_C, full + 28 n_H, full + 4 n_N, full = 440 Subtracting these two numbers shows that 440 - 226 = 214 bonding electrons are needed. Each bond has two electrons, so in addition to the 84 bonds already present in the diagram add 23 bonds. To minimize formal charge nitrogen wants 3 bonds and carbon wants 4 bonds. Identify the atoms that want additional bonds and the number of electrons remaining on each atom. The net charge has been given to the most electronegative atom, nitrogen, in 2 places: Fill in the 23 bonds by pairing electrons between adjacent highlighted atoms, noting the formal charges of the atoms. The six atom rings are aromatic, so that the single and double bonds may be rearranged: Answer: | |