This is so WRONG!

-13.6 eV -40 eV eV

3s Na Cl (-13.7 eV) Br (-12.5 eV) I F (-18.6 eV) F -

-10.6 eV -19 eV -32 eV eV

 (non-bonding)  (bonding)  (anti- bonding)  (anti- bonding)  (bonding)  (non-bonding)

What’s better and worse here?

SPARTAN STUDENT MECHANICS PROGRAM: PC/x Run type: Geometry optimization (Analytical Gradient) (MM/Amide correction used) Model: RHF/PM3 Number of shells: 4 3 S shells 1 P shells Number of basis functions: 6 Number of electrons: 8 Use of molecular symmetry enabled Molecular charge: 0 Spin multiplicity: 1 Point Group = CNV Order = 2 Nsymop = 4 This system has 2 degrees of freedom Initial Hessian option Hessian from MMFF94 calculation used. Max. Max. Neg. Cycle Energy Grad. Dist. Eigen Heat of Formation: kJ/mol Energy Due to Solvation Solvation Energy Semi-Empirical Program CPU Time : 1.53 Semi-Empirical Program Wall Time: 2.10 Use of molecular symmetry enabled Cartesian Coordinates (Angstroms) Atom X Y Z O O H H H H Point Group = CNV Order = 2 Nsymop = 4

Closed-Shell Molecular Orbital Coefficients MO # Eigenvalues: (ev): A1 B1 A1 B2 A1 1 O1 S O1 PX O1 PY O1 PZ H1 S H2 S MO # 6 Eigenvalues: (ev): B1 1 O1 S O1 PX O1 PY O1 PZ H1 S H2 S Atomic Charges: Electrostatic Mulliken Natural 1 O1 : H1 : H2 : Bond Orders Mulliken 1 O1 H1 : O1 H2 : 0.968

bonding Two “O-H bonds” anti-bonding non-bonding Two “lone pairs” but not equivalent!

BH3 Closed-Shell Molecular Orbital Coefficients MO # Eigenvalues: (ev): A1' E' E' A2" A1' 1 B1 S B1 PX B1 PY B1 PZ H1 S H2 S H3 S MO # 6 7 Eigenvalues: (ev): E' E' 1 B1 S B1 PX B1 PY B1 PZ H1 S H2 S H3 S

Mainly F 2s lcao’s Mainly B 2s-F 2p lcao’s Mainly B 2p lcao’s Note  bonds!

Benzene

How does the bonding concepts we’ve seen here relate to what you might have seen before, in Organic?

F donor (sp) orbitals (6) S valence orbitals (9) a 1g OhOh t 1u a 1g t 1u egeg 3s 3p F. z y x 2p F. Instead of; 3d t 2g egeg Because harder to draw Now, can we tackle bigger molecules, like one with six bonds?

F donor (sp) orbitals (6) S valence orbitals (9) a 1g OhOh t 1u a 1g t 1u egeg 3s 3p a 1g t 1u egeg a1ga1g SF 6 F. z y x 2p F. Instead of; 3d t 2g egeg egeg Because harder to draw

a1ga1g OhOh t 1u a1ga1g egeg 3s 3p a1ga1g t 1u egeg a1ga1g SF 6 F. Bonding MO’s 8 e- gives 4 bonds! 3d t 2g egeg egeg

a1ga1g t 1u a1ga1g egeg 3s 3p a1ga1g t 1u egeg a1ga1g SF 6 Two views: A) 4 bonds distributed over six S-F pairs B) 4 bonds (covalent ) + 2 “bonds” ionic (S 6+ -F - )

MO #, Energy, eV Mo(CO) 6 Molybdenum carbonyl Getting Larger: Probably need to use a computer….

MO 1 MO 13 MO 22 MO 24

MO 39 MO 35 MO 44 MO 50 - LUMO MO 49 - HOMO

Sometimes MOs are hard to interpret LUMO HOMO

ML4 - D4h M a.o.’s L a.o.’s

3s Na Cl (-13.7 eV) Br (-12.5 eV) I F (-18.6 eV) F -

a1ga1g OhOh t 1u a1ga1g egeg 4s 4p ML 6 L : 3d t 2g egeg 6  -donors  ONLY, Like H or NH 3 3rd row M, Valence Atomic orbitals

Symmetry Adapted Group Orbitals for 6  -donors

a1ga1g OhOh t 1u a1ga1g egeg 4s 4p a1ga1g t 1u egeg a1ga1g ML 6 L : 3d t 2g egeg egeg 6  -donors  ONLY, Like H or NH 3 3rd row M, Valence Atomic orbitals

a1ga1g OhOh t 1u a1ga1g egeg 4s 4p a1ga1g t 1u egeg a1ga1g ML 6 L : 3d t 2g egeg egeg 6  -donors  ONLY, Like H or NH 3 3rd row M, Valence Atomic orbitals M-L s bonding MO’s M-L s anti-bonding MO’s

a1ga1g OhOh t 1u a1ga1g egeg 4s 4p a1ga1g t 1u egeg a1ga1g ML 6 L : 3d t 2g egeg egeg 6  -donors  ONLY, Like H or NH 3 3rd row M, Valence Atomic orbitals M-L s bonding MO’s M-L s anti-bonding MO’s What is  o?

Symmetry Adapted Group Orbitals for 6  -donors

a1ga1g OhOh t 1u a1ga1g egeg 4s 4p a1ga1g t 1u egeg a1ga1g L : 3d t 2g egeg egeg 6     -donors Like Cl- 3rd row M, Valence Atomic orbitals M-L s bonding MO’s M-L s anti-bonding MO’s 12 L  orbitals t 1u t 1g t 2g t 2u L..

a1ga1g OhOh t 1u a1ga1g egeg 4s 4p a1ga1g t 1u egeg a1ga1g L : 3d t 2g egeg egeg 6     -donors Like Cl- 3rd row M, Valence Atomic orbitals M-L s bonding MO’s M-L s anti-bonding MO’s 12 L  orbitals t 1u t 1g t 2g t 2u t 2g Effect on  o?

a1ga1g OhOh t 1u 4s 4p a1ga1g t 1u ML 6 L : 3d t 2g egeg egeg 3rd row M, Valence Atomic orbitals M-L s bonding MO’s M-L s anti-bonding MO’s 12 L  orbitals t 1u t 1g t 2g t 2u 6     -acceptors Like CO, CN- 12 L  orbitals t 1u t 1g t 2g t 2u t 2g a1ga1g t 1u egeg a1ga1g egeg CO

3d t 2g egeg 12 L  orbitals t 2g egeg 3d t 2g egeg egeg oo 3d t 2g egeg egeg 12 L  orbitals t 2g oo oo Case 1. L is  innocent (sigma donor only) Case 3. L is  acid (sigma donor and  acceptor) Case 2. L is  base (sigma donor and  donor)

ML4 - D4h M a.o.’s L a.o.’s

ML4 - D4h M a.o.’s L a.o.’s d z2 d x2-y2 d xy d xz d yz