Trigonal bipyramidal electron-group arrangement

Figure 10.8 The four molecular shapes of the trigonal bipyramidal electron-group arrangement.

Sp d Hybridization Molecules with shapes due to the trigonal bipyramidal electron-group arrangement have central atoms from Period 3 or higho" because VB theory proposes that d orbitals, as well as s and p orbitals, are mixed to form hybrid orbitals. 

For the trigonal bipyramidal shape of the PCI5 molecule, for example, the VB model proposes that the one 35, the three 3p, and one of the five 3d orbitals of the central P atom mix and form five sp d hybrid orbitals, which point to the vertices of a trigonal bipyramid (Figure 11.6). Seesaw, T-shaped, and linear molecules have this electron-group arrangement with lone pairs in one, two, or three of the central atom s sp d orbitals, respectively. 

What type of central-atom orbital hybridization corresponds to eadi electron-group arrangement (a) trigonal planar, (b) octahedral (c) linear, (d) tetrahedral (e) trigonal bipyramidal ... 

Step 2. Electron-group arrangement With five electron groups, this is the trigonal bipyramidal arrangement. 

The IR spectrum of Me2SnCl2-PyO (Table XVI) contains two intense v(Sn—C) vibrations and a v(Sn—Cl) vibration. The complex was, therefore, assigned (84) a Ila structure, in agreement with the rule of predominantly axial arrangement of electron-donor groups in a trigonal bipyramid (99). In Me2SnCl2 complexes with substituted pyridine V-oxides, a linear... 

Bond arrangements found are tetrahedral, trigonal bipyramidal, and octahedral for completely shared valence groups of 8, 10, and 12 electrons respectively. Higher coordination numbers are exhibited by Sn(iv), 7, and 8, and by Pb(iv), 8, in certain complexes formed by chelating ligands, most or all of the bonds being formed to 0 atoms. 

Molecular Shapes with Five Electron Groups (Trigonal Bipyramidal Arrangement)... 

---