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Complex ion
Transition metal bound to multiple ligands that carries a charge
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Ligands
Molecules or ions that are attached to a transition metal (NH3)
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Counter Ions
Ions that balance charge. Not part of the complex ion
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Coordination Number (CN)
- -Number of bonds to the transition metal
- -for polydentate ligands, each "tooth" counts for one
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CN=2
CN=4
CN=4
CN=6
linear, tetrahedral, square planar, octahedral
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How to find the charge on
[Co(NH3)6]Cl3
- -Charge for each NH3 is 0, so metal is 3+
- -Becomes [Co(NH3)6]3+
- -Switch the metal w/outside ion
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Name [Co(NH3)6]Cl3
Steps and name
hexaamminecobalt(III)chloride
- -Name cation before anion
- -Name ligand before metal ion
- -If ligand is an anion, put "o" at end of name (chloro)
- -If ligand is neutral, use regular name (except exceptions)
- -Roman numeral to designate metal oxidation state
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Neutral: (*=exception)
H2O *
NH3 *
CO *
NO *
CH3NH2
aqua, ammine, carbonyl, nitrosyl, methylamine
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F-
Br-
Cl-
I-
OH-
CN-
fluoro, bromo, chloro, iodo, hydroxo, cyano
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Prefixes: simple ligands
1
2
3
4
5
6
none, di, tri, tetra, penta, hexa
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Prefixes: complicated ligands
1
2
3
4
none, bis, tris, tetrakis
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Name [CoBr(NH3)5]SO4
pentaaminebromocobalt(III)sulfate
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Metal complexes as anions:
Name [K3CoF6] and steps
potassium hexafluorocobaltate(III)
- -Cation always first
- -Add -ate to the end of the metal name
- -If name ends with -ium, drop the -ium
- -Some exceptions where you use the Latin name of the element instead
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Isomers
Molecules with same molecular formulas but different arrangements
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Coordination Isomerism
- -Different ligands in complex
- -[Cr(NH3)5Cl]Br vs [Cr(NH3)5Br]Cl
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Linkage isomerism
- Different binding sites on the ligand
- -Double bond v single bond sometimes
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Geometric Isomers
-Different arrangements of ligands around central atom
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cis
ligands are side-by-side
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trans
ligands are across from each other
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cis-platin vs. trans-platin
Cis is a potent anti-tumor agent while trans-platin is ineffective against tumors
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Geometric Isomers: Angles
Cis=
Trans=
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Optical Isomers
- -Non-superimposable mirror images
- -Ex: Hands
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Chiral Molecule
Type of molecule that has a non-superimposable mirror image
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Enantiomers
Pair of molecules that are non-superimposable mirror images (also called optical isomers)
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2 assumptions of crystal field theory
- -Ligands=negative point charges
- -Metal-ligand bonds are ionic bonds
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Name the 5 possible d orbitals
dz2, dx2-y2, dyz, dxy, dxz
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In the absence of ligands, d orbitals are
degenerate (equal in energy)
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Octahedral arrangement of d orbitals
- Top 2: dz2, dx2-y2
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Octahedral arrangement direction of orbitals to point charges
Energy increase
- Top 2: directed toward point charges
- Bottom 3: Between point charges
-Energy of these orbitals not raised by as much
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What gives transition metal complexes their colors
Where is this located
- -the energy of absorbed photon
- -typically in visible region of the spectrum
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What do you observe in the color wheel?
You observe the complementary color of the light absorbed by the complex
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Spectrochemical Series
- -Based on experiment
- -Ranks ligands from weakest field to strongest field
- I-<Br-<Cl-<F-<OH-<H2O<NH3<en<NO2-<CN-
- Weakest--Strongest
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Strong field case
[Co(CN)6]3-
- -Large /\E
- -Ground state: can not populate dx2-y2 and dz2-Low electron spin
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Weak field case
[CoBr6]3-
- -Small /\E
- -Ground state: can populate dx2-y2 and dz2-High electron spin
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d-Splitting in Tetrahedral Complexes
Positions of ligands are __
Orbitals never point directly at __
Ligands are closest to __
- -Positions of ligands are different
- -Orbitals never point directly at ligands =>Smaller splitting
- -Ligands closest to dxy, dyz, dxz
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d-Splitting in tetrahedral complex
Order of split energy levels is __
Gap between /\E levels is __
All tetrahedral complexes have __ fields and __ spin
opposite, smaller, weak, high
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Ligand Field Theory:
-What inaccurate theory assumed that ligand-metal bonds are ionic?
-Utilizes concept of __
-Ligand field theory accounts for __ bonding of __ to __
crystal field theory, molecular orbital theory, covalent, ligands, metal
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Organic Molecules
Compounds containing carbon
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