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12/4/2015
1
Advanced Inorganic Chemistry
Alireza [email protected]
Department of Chemistry, Yazd University
20_441
Isomers
(same formula but different properties)
Stereoisomers
(same bonds, different
spatial arrangements)
Structural
isomers
(different bonds)
Optical
isomerism
Geometric
(cis-trans)
isomerism
Linkage
isomerism
Coordination
isomerism
Isomerism ایزومری
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Ionization Isomerism ایزومری یونش
[CrSO4(NH3)5]Cl
[CrCl(NH3)5]SO4
pentaaminsulfatochromium(III) chloride
pentaaminchlorochromium(III) sulfate
Hydrated Isomerism ایزومری آب پوشی
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[Co(NH3)4(NO2)Cl]Cl & [Co(NH3)4(ONO)Cl]Cl
[Co(SCN)(NH3)5]+ & [Co(NCS)(NH3)5]
+
Ambidentate Ligands لیگاندهای دوسردندانه
NCS- NO2- R-CONH2
Linkage Isomerism ایزومری اتصال
[Co(NH3)5(NO2)]Cl2Pentaamminenitrocobalt(III) chloride
[Co(NH3)5(ONO)]Cl2Pentaamminenitritocobalt(III) chloride
Linkage Isomerism ایزومری اتصال
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- Electronic effect
- Steric effect
- Solvent effect
- Lattice effect
- Counter ion effect
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20_441
Isomers
(same formula but different properties)
Stereoisomers
(same bonds, different
spatial arrangements)
Structural
isomers
(different bonds)
Optical
isomerism
Geometric
(cis-trans)
isomerism
Linkage
isomerism
Coordination
isomerism
Isomerism ایزومری
Stereoisomerism استریوایزومری1- Geometric isomerism
1. Geometric isomerism (cis-trans):
Pt(NH3)2Cl2
2. Geometric isomerism (fac-mer):
IrH3(PR3)3
• Atoms or groups arranged differently spatially relative to metal ion
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Geometric Isomerism ایزومری هندسی
cis-trans ترانس–سیس
ML3X3•fac (facial) وجهی
three identical ligands occupying the
corners of a common triangular
•mer (meridional) کمربندی
three identical ligands occupying three
consecutive corners of a square plane
Geometric Isomerism ایزومری هندسی
fac-mer کمربندی –وجهی
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تحمیل ایزومری به وسیله لیگاند
fac فقط mer فقط [email protected]
2- StereoisomerismStereoisomerism استریوایزومری
2- Optical isomerism نوری ایزومری
18
Sn S1= S2=i
Cn Dn
Chiral Complexes
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Chiroptic Techniques
•Plane and circularly polarized light
•Definitions of terms
•Optical rotary dispersion (ORD)
•Circular dichroism (CD)
Types of polarized light
• Plane polarized light consists two circularly polarized components of equal intensity
• Two circularly polarized components are like left-and right-handed springs
• As observed by looking at the source, right-handed circularly polarized light rotates clockwise
• Frequency of rotation is related to the frequency of the light
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optically inactive, nL= nR
Plane Polarized Light
Plane Polarized Light
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Optical Rotation
optically inactive, nL= nR
optically active, nL nR
n=c/cv
Optical Rotatory Dispersion (ORD)
moleper gramsin MW theis where,)cm M (deg ][][ rotation Molar
(g/mL)ion concentrat theis and (cm)length path theis where, rotation Specific
line) D Na the589;(normally •
180rotation of angle observed The
1-1-
RL
Mdc
MM
cddc
nnd
The technique of optical rotatory dispersion (ORD)
examines the wavelength dependence of optical activity.
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• Positive Cotton effect
• Negative Cotton effect
The Cotton Effect in ORD
Circular Dichroism
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Circular Dichroism
• is therefore the angle between the initial plane of polarization and the major axis of the ellipse of the resultant transmitted light
• A quantity is defined such that tan is the ratio of the major and minor axis of the ellipse of the transmitted light
• ’ approximates the ellipticity
• When expressed in degrees, ’ can be converted to a specific ellipticity [] or a molar ellipticity []
• CD is usually plotted as []
θ100.3032εε
10θ y ellipticitmolar
dc' y ellipticit specific
3
rl
2
M
Circular Dichroism
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)(3300
).( y"ellipticit" as CD express sinstrument commercial reasons, historicalFor
)()()(
RLCD
Optical rotatory dispersion (ORD) and circular dichroism (CD) are mathematically
related. If you measure one, you can calculate the other by means of functions called
Kronig-Kramers Transforms.
dM
dM
o
o
o
o
o
o
22
22
][2][
2
CD is more commonly used than ORD
to study molecules.
- Better resolution
- Better sensitivity.
- Easier to [email protected]
ORD, CD and UV of Camphor
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Use of CD and ORD spectra
1- Determination of absolute configuration (&)
2- Assignment of Electronic spectra
1- Determination of absolute configuration (&)
Reference:d6 low spin
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1- Determination of absolute configuration (&)
2- Assignment of Electronic spectra