Square pyramidal molecular shape

The square pyramidal geometry of CIF5 completes our inventory of molecular shapes. Figure 9-26 summarizes the characteristics of atoms with steric number 6. 

C09-0129. Tellurium compounds, which are toxic and have a hideous stench, must be handled with extreme care. Predict the formula of the tellurium-fluorine molecule or ion that has the following molecular geometry (a) bent (b) T-shaped (c) square pyramid (d) trigonal bipyramid (e) octahedron and (Q seesaw. 

The first molecular structure of half-sandwich lanthanide porphyrins was reported by Schaverien and Orpen (1991). The lutetium alkyl complex Lu(OEP)[CH(SiMc3)2] has a structure resembling that of the scandium analog (Arnold et al. 1993), exhibiting a square pyramidal geometry. The five-coordinated lutetiiun atom lies 0.918 A above the N4 plane, and the porphyrin ring also displays a saucer shape. 

Solution. The molecular geometries of BrF5 and BrF3 are square pyramidal and T-shaped, respectively, as shown in the following diagram. 

Step 4. Molecular shape With one lone pair, BrFj has the square pyramidal shape (AX5E) ... 

The molecular structures of some representive neutral interhalogens, (a) chlorine trifluoride, CIF3 (distorted T-shaped) b) bromine pentafluoride, BrFs (square pyramidal) (c) iodine heptafluoride, IF7 (pentagonal bipyramidal) and (d) diiodine hexachloride, I2CI6 (planar dimer). 

Correlation diagram for the molecular orbital levels of A—H, T-shaped AH3, and square pyramidal AH5. As in earlier figures we show the effect of the new orbitals by the use of dashed tie lines. 

Practice Problem B For which molecular geometries (linear, bent, trigonal planar, trigonal pyramidal, tetrahedral, square planar, T-shaped, seesaw-shaped, trigonal bipyramidal, square pyramidal, octahedral) can an AB, molecule be nonpolar if there are (a) two drflerent types of terminal atoms and (b) three different types of terminal atoms ... 

---