Which of the following species has a linear structure: \(\mathrm{ClF}_{2}^{+}, \mathrm{IBrF}^{-}, \mathrm{OCl}_{2}, \mathrm{ClF}_{3},\) or \(\mathrm{SF}_{4} ?\) (Central atom underlined.) Do any two of these species have the same structure?

First, create the Lewis structures for each molecule and determine the electron domain geometry. Use the following information: a) ClF2+ has 7(1)+7(2)+1 = 22 total valence electrons (VE), b) IBrF- has 7(3)-1 = 20 VE, c) OCl2 has 6(1)+7(2) = 20 VE, d) ClF3 has 7(1)+7(3) = 28 VE, e) SF4 has 6(1)+7(4) = 34 VE.

Compare the configuration of bonding and non-bonding electron pairs to known molecular geometries. a) ClF2+ has three electron domains (the Cl atom is surrounded by two single bonds and one lone pair), which would give a trigonal planar electron domain geometry. However, with one lone pair, the molecular geometry becomes bent or V-shaped. b) IBrF- also has three electron domains, but the molecular geometry is linear because the central iodine atom has two lone pairs, leaving the F and Br atoms on opposite ends. c) OCl2 has three electron domains with no lone pair, which is a bent or V-shaped structure. d) ClF3 has five electron domains resulting in a T-shaped molecular geometry. e) SF4 has five electron domains with one lone pair, creating a see-saw structure.

Now compare the geometries of the molecules. Only IBrF- has a linear structure. None of the species share the same molecular structure.