Ligand Group Orbitals Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

What can you do to the following shapes so they are indistinguishable before and after? Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Proper rotation (C n ) Define an axis and rotate counterclockwise 360/n is how many o the rotation is Example – NH 3 Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Reflection (  ) Pass a mirror plane through an object Types of mirror planes  Horizontal (  h ) – perpendicular to the PA  Vertical (  v ) – contains PA passes through outer atoms  Dihedral (  d ) – contains PA misses outer atoms Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Improper rotation (S n ) n have same meaning as proper rotations Rotate by n along an axis Reflect perpendicular to that axis Can be coincidental with a proper rotation axis Not of major concern for us Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Set of symmetry operations that describes a molecule  Mathematical treatment of groups Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

Is the molecule of low symmetry? C1, Cs, C i Is the molecule of high symmetry? Td, Oh, C ∞ v, D ∞ h, I h Highest-order rotation axis (Cn) Perpendicular C2’s? D groups  h? Dnh  d? DndDn C or Sn groups h?h? Cnh  v? CnvS2n? S2nCn Yes C 1 – No symmetry C s – Just a mirror plane C i – Just an inversion center No High symmetry groups typically have many symmetry operations Consider SF 6 Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Determine the point group for… NH 3 Cyclopropane Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

Is the molecule of low symmetry? C1, Cs, C i Is the molecule of high symmetry? Td, Oh, C ∞ v, D ∞ h, I h Highest-order rotation axis (Cn) Perpendicular C2’s? D groups  h? Dnh  d? DndDn C or Sn groups h?h? Cnh  v? CnvS2n? S2nCn Yes No Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Determine the point group for… NH 3 C 3v Cyclopropane D 3h Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Draw a Lewis structure and assign VSEPR geometry  Assign a point group to the molecular geometry  Determine the VB hybrid orbitals for the electronic geometry of the central atom  Use the VB hybrid orbitals as generator functions  Generate the Ligand Group Orbitals (LGOs) by combining the ligand σ -orbitals to obtain an orbital with the same symmetry as the generator function  Assign symmetry labels to the LGOs from the character table by matching the label of the generator function Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Draw the Lewis structure B has 3 valence electrons H has 1 valence electron B.... H. H. H The molecular geometry is? AX 3 – trigonal planar What is the point group? Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

Is the molecule of low symmetry? C1, Cs, C i Is the molecule of high symmetry? Td, Oh, C ∞ v, D ∞ h, I h Highest-order rotation axis (Cn) Perpendicular C2’s? D groups  h? Dnh  d? DndDn C or Sn groups h?h? Cnh  v? CnvS2n? S2nCn Yes No D 3h Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 The electron geometry is AX 3 E 0  This is an electron deficient molecule  From General Chemistry – sum X and E 2 – sp 3 – sp 2 4 – sp 3 5 – sp 3 d 6 – sp 3 d 2 Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Considering the boron atom  We need to assign axes  An abbreviated character table y x z D 3h Orbital A1′A1′ s A2′A2′ E′E′ p x, p y A 1 ′′ A 2 ′′ pzpz E ′′ A1′A1′ E′E′ E′E′ A 2 ′′ Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

A1′A1′ E′E′ E′E′ A 2 ′′ Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

E B3 H BH 3 A1′A1′ A 1 ′ (  ) E′E′ E ′ (  ) A 2 ′′ (nb) A 2 ′′ E′E′ E′E′ E′E′ A1′A1′ A 1 ′ (   ) E ′ (   ) Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

A 1 ′ (  ) E ′ (  ) A 2 ′′ (nb) A 1 ′ (   ) E ′ (   ) Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Draw the Lewis structure  What is the molecular geometry?  What is the point group?.. AX 2 – bent based on tetrahedral Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

Is the molecule of low symmetry? C1, Cs, C i Is the molecule of high symmetry? Td, Oh, C ∞ v, D ∞ h, I h Highest-order rotation axis (Cn) Perpendicular C2’s? D groups  h? Dnh  d? DndDn C or Sn groups h?h? Cnh  v? CnvS2n? S2nCn Yes No C 2v Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 What’s the electron geometry?  What is the hybridization on oxygen?  Assign axes AX 2 E 2 sp 3 z x y Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

C 2v Orbital A1A1 s, p z A2A2 B1B1 pxpx B2B2 pypy A1A1 B2B2 A1A1 B1B1 Are there any that cannot interact with the H atoms? GeneratorSymmetryLigandsLone pair sA1A1 Yes pzpz A1A1 pypy B2B2 NoYes pxpx B1B1 No Can interact with Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

A1′A1′ A1A1 B1B1 B2B2

E O2 H H2OH2O A1A1 A1 ()A1 () B1B1 B 1 (  ) A 1 (lp) B 2 (lp) B2B2 A1A1 B1B1 A1A1 B1 ()B1 () A 1 (   ) Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 Draw the Lewis structure  What is the molecular geometry?  What is the point group? AX 5 – trigonal bipyramidal Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

Is the molecule of low symmetry? C1, Cs, C i Is the molecule of high symmetry? Td, Oh, C ∞ v, D ∞ h, I h Highest-order rotation axis (Cn) Perpendicular C2’s? D groups  h? Dnh  d? DndDn C or Sn groups h?h? Cnh  v? CnvS2n? S2nCn Yes No D 3h Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

 What’s the electron geometry?  What is the hybridization on phosphorus?  Assign axes AX 5 E 0 sp 3 d z x y Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

D 3h Orbital A1′A1′ s, d z 2 A2′A2′ E′E′ p x, p y A 1 ′′ A 2 ′′ pzpz E ′′ A1′A1′ E′E′ E′E′ A 2 ′′ A1′A1′ Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

A1′A1′ E′E′ E′E′ A 2 ′′ A1′A1′ X Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.

E PPF 5 5 F A 2 ′′ (  *) E ′′ (  *) A 1 ′ (  *) A 2 ′′ (  ) E ′′ (  ) A 1 ′ (  ) A 2 ′′ E ′′ A1′A1′ A1′A1′ A 1 ′ (nb) A 2 ′′ E ′′ A1′A1′ Created by Chip Nataro (Lafayette College and posted on VIPEr ( on March 27, Copyright Chip Nataro This work is licensed under the Creative Commons Attribution Non-commercial Share Alike License.