Molecular Shape II PDF

Pharmaceutical Chemistry Molecular Shape II Dr. J.J. Keating 1 Molecular Shape – AB3E (Trigonal Pyramidal) N H H H NH3 ammonia...

Pharmaceutical Chemistry Molecular Shape II Dr. J.J. Keating 1 Molecular Shape – AB3E (Trigonal Pyramidal) N H H H NH3 ammonia 2 Molecular Shape – AB3E (Trigonal Pyramidal) N H H H NH3 ammonia 3 Molecular Shape – AB2E2 (Bent, Angular, V-shaped) H O H H2O water 4 Molecular Shape – AB2E2 (Bent, Angular, V-shaped) H O H H2O water 5 Molecular Shape – AB2E2 (Bent, Angular, V-shaped) H O H H2O water 6 Molecular Shape – AB2E2 (Bent, Angular, V-shaped) O H H H O H 7 Molecular Shape – AB4E2 (Square Planar) Cl Cl Pt NH3 H3N cis-PtCl2(NH3)2 cisplatin 8 Molecular Shape – AB4E2 (Square Planar) Cl Cl Pt H3N NH3 cis-PtCl2(NH3)2 cisplatin 9 Molecular Shape – AB6 (Octahedral) F F F S F F + S F  O O SF6 sulfur hexafluoride 10  Molecular Shape – SF6 (Octahedral) SF6 – colourless, odourless, non-flammable, b.p. –64 °C, density = 6.2 g/L (denser than air). SonoVue® – 1 mL contains 8 μL SF6 microbubbles. Used with ultrasound imaging to enhance the echogenicity of the blood, which results in improved signal to noise ratio (echocardiography). www.ema.europa.eu https://www.youtube.com/watch?v=u19QfJWI1oQ SF6 sulfur hexafluoride 11  Molecular Shape – AB6 (Octahedral) O Na+ O Na+ HO O  O O OH O  N N N N HO O OH HO O OH O O EDTA Na2EDTA ethylenediaminetetraacetic acid disodium edetate chelating agent M = metal ion such as Fe2+ EDTA chelates divalent transition metal ions, forming an octahedral complex eye lubricant for dry eyes 12  Molecular Shape – AB6 (Octahedral) When FeSO4 dissolves in water, the Fe2+ ions form an octahedral complex with water molecules. OH2 OH2 FeSO4 H2O Fe2+ OH2 ferrous sulfate H 2O OH2 Fe(H2O)62+ ferrous hexaaqua ion 13  VSEPR Theory Central atom (A) Calculate number of valence electron pairs Calculate number of valence bonding (B) and non-bonding (E) pairs. CH4 SO32– AB4 AB3E Angle – theory – 109.5° Angle – theory – 109.5° Angle – actual – 109.5° Angle – actual – 106° sulfite methane Lone/lone pair repulsions > lone/bonding pair repulsions > bonding/bonding pair repulsions. Energetically more favourable for lone pairs to be as far from one another as possible. Energetically more favourable for bonding pairs to be as far from lone pairs even though it might bring them closer to other bonding pairs. SO32– angle = 106°, H2O angle = 104.5°, NH3 angle = 107°. 14  VSEPR Theory Treat a multiple bond as though it were a single bond. Treating multiple bonds as single bonds removes the issue of which of several resonance structures to use. S+ O O SO2 H H sulfur dioxide C2H2 ethyne H H C6H6 O benzene H H CH2CH2 CH3COCH3 ethene acetone 15  VSEPR Theory – Terbinafine t-butyl methyl trans-alkene methylene N alkyne naphthalene 16