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Structure and hybridization. - The Fock-equation yields the electronic structure of a molecule for a given geometry. The canonical MOs do not reflect the molecule’s geometry. - Hybridization is an alternative way to obtain the electronic
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Structure and hybridization - The Fock-equation yields the electronic structure of a molecule for a given geometry. The canonical MOs do not reflect the molecule’s geometry. - Hybridization is an alternative way to obtain the electronic structure of a molecule, which does show a clear relation with the geometry of the molecule. Hybridization is the mixing of atomic orbitals with different l-quantum numbers on the same atom.
Structure and hybridization (continued) - Normal atomic orbitals (s, p, d, …) have a well-defined center; i.e., an atomic nucleus. - Normal atomic orbitals may have a well-defined orientation; e.g., p orbitals are oriented along an axis of the reference frame. - Normal atomic orbitals do not have a direction; pz points as much in the +z as in the -z direction. - Normal atomic orbitals are not well suited to form MOs that correspond to bonds between two atoms. - Combining atomic orbitals with different l-quantum numbers produces hybrids that do have a specific direction.
Structure and hybridization (continued) s orbital p orbital sp hybrid
Structure and hybridization (continued) These hydrids point in these directions. MOs: Slater-determinant: CH4 revisited: They are sp3-hybrids.
Structure and hybridization (continued) indication of C atom direction of bonds involving C bonding orbitals for C-H bond Molecules with tetrahedral angles: C2H6 sp3-hybrid on C bonding orbital for C-C bond Slater-det.:
Structure and hybridization (continued) direction of bonds involving N bonding orbitals for N-H bonds lone-pair orbital Molecules with tetrahedral angles: NH3 sp3-hybrid on N Slater-det.:
Structure and hybridization (continued) MOs: Slater-determinant: Molecules with 120o angles: BH3 These are sp2-hybrids.
Structure and hybridization (continued) indication of C atom direction of bonds involving C Molecules with 120o angles: C2H4 sp2-hybrid on C C-H bond bonding orbital for C-C bond (s bond) bonding orbital for C-C bond (p bond) Slater-det.:
Structure and hybridization (continued) MOs: Slater-determinant: Molecules with 180o angles: BeH2 These are sp-hybrids.
Structure and hybridization (continued) indication of C atom direction of bonds involving C Molecules with 180o angles: C2H2 sp-hybrid on C C-H bond C-C bond (s bond) C-C bond (p bond) C-C bond (p bond) Slater-det.: