Octahedral geometry molecular

The Lewis stmeture of SFg, shown in Figure 9-24a. indicates that sulfur has six S—F bonds and no lone pairs. The molecular geometry that keeps the six fluorine atoms as far apart as possible is octahedral in shape, as Figure 9-24Z) shows. Figure 9-24c shows that an octahedron has eight triangular faces. 

The molecular geometry of a complex depends on the coordination number, which is the number of ligand atoms bonded to the metal. The most common coordination number is 6, and almost all metal complexes with coordination number 6 adopt octahedral geometry. This preferred geometry can be traced to the valence shell electron pair repulsion (VSEPR) model Introduced In Chapter 9. The ligands space themselves around the metal as far apart as possible, to minimize electron-electron repulsion. 

The Lewis formula predicts 6 electron groups around the central Xe atom and its electronic geometry is octahedral. The molecular geometry is square planar due to the presence of 2 lone pairs of electrons on the central Xe atom. 

This molecule (type AB6) has an octahedral electronic and molecular geometry. The S-F bonds are polar, but the molecule is symmetrical. The S-F bond dipoles cancel to give a nonpolar molecule (Section 8-12). 

Values of umn, umx and uM for synunetrical tetrahedral (MZ3), trigonal bipyramidal (MZ4), and octahedral (MZ5) groups can be obtained from Eq. 17 using the rv values calculated from Eq. 1-3 and 6-10. Values of rV mn, rv,mi and rV-ax for symmetrical bicycloalkyl and heterobicycloalkyl groups can be calculated from molecular geometry. The appropriate values are then obtainable from Eq. 17. 

WhenP = 6. as in SF, . the structure is simple, because all the pairs are bond >airs, and the molecular geometry is the same as the electron-pair geometry it s octahedral (Figure lM2). 

B Methane has a molecular geometry that is tetrahedral, while BF3 is trigonal planar in shape and XeF6 is octahedral in shape. 

Although the model was originally proposed for octahedral complexes, it has been applied in modified forms to other molecular geometries 20, 39, 48). In general it has been used, with a reasonable degree of success, for band assignments, although its limitations, and even its validity, have been discussed (Section I). 

In an SFg molecule we have six valence shell electron pairs and six F atoms surrounding one S atom. Because the valence shell of sulfur contains no lone pairs, the electronic and molecular geometries in SFg are identical. The maximum separation possible for six electron pairs around one S atom is achieved when the electron pairs are at the comers and the S atom is at the center of a regular octahedron. Thus, VSEPR theory is consistent with the observation that SFg molecules are octahedral. 

By similar reasoning, VSEPR theory predicts octahedral electronic geometry and octahedral molecular geometry for the PFg ion, which has six valence shell electron pairs and six F atoms surrounding one P atom. 

Octahedral A term used to describe the electronic geometry around a central atom that has six regions of high electron density. Also used to describe the molecular geometry of a molecule or polyatomic ion that has one atom in the center bonded to six atoms at the corners of an octahedron (ABg). 

We have seen that hybridization neatly explains bonding that involves and p orbitals. For elements in the third period and beyond, however, we cannot always account for molecular geometry by assuming that only. y and p orbitals hybridize. To understand the formation of molecules with trigonal bipyramidal and octahedral geometries, for instance, we must include d orbitals in the hybridization concept. 

Examples of hexacoordinated q2 - BH4 complexes are known with octahedral (2.6a/T2.6) and distorted octahedral molecular geometries (2.6b). All of these structures present at least one hydride and two phosphino ligands. The metal centres are d4-Group 6 or Group 8 transition metals. The OsH3(BH4)(P Pr3)2 complex exhibits interesting dynamical features which have been computationally studied [14,15] and will be discussed with more detail in Sect. 4. 

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