lecture on exp 4a

lecture on exp 4a - CHEM 6BL Experiment 4A: Iron Oxalate...

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Unformatted text preview: CHEM 6BL Experiment 4A: Iron Oxalate Complex Synthesis Instructor: Dr. S. Berniolles Page 1 Experiment #4 Concepts & Objectives Experiment #4 Concepts & Objectives Inorganic Synthesis (Experiment 4A) Coordination Compounds & Complex Chemistry 1 Stoichiometry: Limiting Reagent & % Yield Redox Reactions Product Analysis : Redox Titrations & Spectrophotometry ( Experiments #4B & #4C ) Experiment 4A Experiment 4A : Inorganic Synthesis : Inorganic Synthesis Expt. #4A involves Complex Chemistry Fe(NH 4 ) 2 (SO 4 ) 2 6H 2 O Fe 2+ 2 SO 4 2- = 4- 2 4 2 4 2 2 K w [Fe x (C 2 O 4 ) y ]zH 2 O 2 NH 4 + = 2+ K + Fe 3+ C 2 O 4 2- Coordination Compound Coordination Compound Electrically neutral compound in which at least one of the ions present is a complex , a species consisting of: 3 A central metal atom/ion (usually a transition metal) Ligands (neutral molecules or anions that have at least one atom with a lone pair of electrons) CHEM 6BL Experiment 4A: Iron Oxalate Complex Synthesis Instructor: Dr. S. Berniolles Page 2 Coordination Complex Coordination Complex Central metal atom/ion is a transition metal Transition metals act as strong Lewis Acids Lewis Acids i.e., e- pair acceptors 4 Ligands bond to the metal center Ligands are Lewis Bases Lewis Bases i.e., e- pair donors Examples: H 2 :, :NH 3 neutral molecules :H- , :Cl- charged ions Coordination Number (C.N.) Coordination Number (C.N.) C.N. = Number of electron pairs donated to the metal center 5 Commonly, C.N. = 2, 4, 6 Ag(NH 3 ) 2 + C.N. = 2 Fe(Cl) 4 C.N. = 4 Fe(H 2 O) 4 (CN) 2 C.N. = 6 Complex Geometries: Complex Geometries: C.N. = 2 C.N. = 2 C.N. = 2: Linear Compound Simplest shape 6 Example : H 3 N Ag + NH 3 CHEM 6BL Experiment 4A: Iron Oxalate Complex Synthesis Instructor: Dr. S. Berniolles Page 3 Complex Geometries: Complex Geometries: C.N. = 4 C.N. = 4 C.N. = 4: Tetrahedral Cl 7 C.N. = 4: Square Planar Fe Cl Cl Cl NC CN NC CN Pt 2+ Complex Geometries: Complex Geometries: C.N. = 6 C.N. = 6 C.N. = 6: Octahedral The vast majority of these complexes 8 H 3 N NH 3 NH 3 Cl H 3 N Cl Co 3+ Ligand Types Ligand Types Some ligands bind at more than one site around the metal (i.e., have >1 Lewis base site) Monodentate : binds just at one metal site Most ligands: e g NH H O C etc 9 Most ligands: e.g. NH 3 , H 2 O, Cl , etc. Bidentate : can bind at two metal sites Ex: C 2 O 4 2 , ethylenediamine (en - NH 2 CH 2 CH 2 NH 2 ) Tridentate : can bind at three metal sites Ex: diethylenetriamine (dien) Hexadentate : can bind at six metal sites Ex: ethylenediaminetetraacetato (EDTA) CHEM 6BL Experiment 4A: Iron Oxalate Complex Synthesis Instructor: Dr. S. Berniolles Page 4 Polydentate Polydentate Ligands Ligands (Chelating Agents) (Chelating Agents) : M H C C C O-- O O 10 : N C H 2 C H 2 CH 2 H 2 C H 2 N NH 2 H H 2 C CH 2 N N CH 2 CH 2 H 2 C H 2 C C C O O...
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lecture on exp 4a - CHEM 6BL Experiment 4A: Iron Oxalate...

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