Concept explainers
(a)
Interpretation:
The orbital picture of
Concept introduction:
Orbital picture of a molecule can be built up by first determining which orbitals will overlap and interact effectively. These are generally the orbitals from the valence shell of the atoms forming the bonds; mostly s and p orbitals. The orbital that will overlap end-on and the ones that overlap sideways are then determined on the basis of the electron geometry of the atoms. End on overlap leads to
(b)
Interpretation:
The total number of MOs of
Concept introduction:
Sideways interaction of AOs produces MOs of
The number of MOs produced is same as the number of contributing AOs.
(c)
Interpretation:
The orbital energy diagram for CO is to be drawn and the HOMO and LUMO identified.
Concept introduction:
The molecular orbital energy diagram of a molecule is built up by considering the interactions of all the valence shall orbitals from each atom. The total number of MOs produced is the same as the number of interacting AOs.
An end-on overlap of two orbitals produces a pair of MOs of
Interactions between p orbitals produces MOs of two types, one pair with a
The valence electrons of the contributing atoms are then filled in these MOs in increasing order of energy. The MO of highest energy that contains any electrons is called the highest occupied molecular orbital (HOMO), and the empty MO immediately above it is called the lowest unoccupied molecular orbital (LUMO).
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Chapter 3 Solutions
ORGANIC CHEMISTRY E-BOOK W/SMARTWORK5
- For each of the following molecules, construct the MOs from the 2pz atomic orbitals perpendicular to the plane of the carbon atoms. (a) Cyclobutadiene HC (b) Allyl radical Indicate which, if any, of these orbitals have identical energies from symmetry considerations. Show the number of electrons occupying each MO in the ground state, and indicate whether either or both of the molecules are paramagnetic. Assume that the C atoms in the allyl radical are all sp2 hybridized.arrow_forwardDetermine the point groups of the following molecules. a Fe(CO)5, which has a trigonal bipyramidal structure, b CO32, which has three resonance structures that contribute to its overall shape, c The perfectly staggered conformation of ethane, d The perfectly eclipsed conformer of ethane.arrow_forwardConstruct the molecular-orbital energy level diagramsof (a) ethene and (b) ethyne on the basis that the moleculesare formed from the appropriately hybridized CH2 or CH fragmentsarrow_forward
- Sketch the MO diagram for 1,3 butadienearrow_forwardBased on the shapes of p and d orbitals and the necessary match of symmetry,please predict and sketch all of the possible orbital interactions between the porbitals of atom A and the d orbitals of atom B for the formation of bonding andantibonding orbitals?arrow_forwardFor each of these contour representations of molecular orbitals,identify (a) the atomic orbitals (s or p) used to constructthe MO (b) the type of MO (s or p), (c) whether the MO isbonding or antibonding, and (d) the locations of nodalplanes.arrow_forward
- Draw the MO diagram of linear NO2 by consulting the character tables and orbital energies, and to align your O/N/O axes. Remember to use a lower symmetry point group for the linear molecule. What is the bond order of linear NO2? How does it change if you make it NO2 - or NO2 +. Draw each SALC and look for interactions between the orbitals.arrow_forwardDraw a pz and a dz2 orbital and assign their point groups.arrow_forwardFor monocyclic conjugated polyenes (such as cyclobutadiene and benzene) with each of N carbon atoms contributing an electron in a 2p orbital, Huckel theory gives the fol lowing expression for the energies Ek of the resulting π molecular orbitals Calculate the energies of the 1t molecular orbitals of benzene and cyclooctatetraene. Comment on the presenceor absence of degenerate energy levels. (b) Ca lcu late and compare the delocalization energies of benzene and hexatriene using the expression from the preceding problem. What do you conclude from your results? (c) Calculate and compare the delocalization energies of cyclooctatetraeneand (linear) octatetraene. Are your conclusions for th is pair of molecules the same as for the pair of molecules investigated in part (b)?arrow_forward
- Provide possible molecular structures for NbF5 with C4v and D3h point groupsarrow_forwardSketch the MO diagram for 1,3 budadiene. Identify the HOMO and LUMO along with all symmetric MO’s, asymmetric MO’s, bonding MO’s, and anti bonding MO’s.arrow_forwardFor conjugated systems with two, three, four, five, six, and seven conjugated p bonds, construct quick MOs to show whether the HOMO is symmetric or antisymmetric.arrow_forward
- Principles of Modern ChemistryChemistryISBN:9781305079113Author:David W. Oxtoby, H. Pat Gillis, Laurie J. ButlerPublisher:Cengage LearningPhysical ChemistryChemistryISBN:9781133958437Author:Ball, David W. (david Warren), BAER, TomasPublisher:Wadsworth Cengage Learning,