ch8 coordination [호환...
TRANSCRIPT
![Page 1: Ch8 Coordination [호환 모드]chem.yonsei.ac.kr/~mhmoon/pdf/General_Oxtoby/Ch8_Coordination.pdf · 8.3 8.1 chemistry of Transition Metals transition metal elements : partially filled](https://reader030.vdocuments.net/reader030/viewer/2022021609/5b51040e7f8b9ae22c8b893f/html5/thumbnails/1.jpg)
8.1
Chapter 8Bonding in Transition Metal
C d & C di i C lCompounds & Coordination Complexes Emerald: Beryllium aluminum silicatey
Prof. Myeong Hee Moon
8.2
Chapter Outline
• Chemistry of transition metals
• Bonding in simple molecules that contain treansition metals
• Introduction to coordination chemistry
St t f di ti l• Structures of coordination complexes
• crystal field theory : optical & magnetic properties
• optical properties & spectrochemical series
• Bonding in coordination complexes• Bonding in coordination complexes
Prof. Myeong Hee Moon
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8.3
8.1 chemistry of Transition Metals
transition metal elements : partially filled d-electron shells wide variety of geometric strctures colors magnetic propwide variety of geometric strctures, colors, magnetic prop
• physical properties: IE & IE increases across: IE1 & IE2 increases across: atomic and ionic radii decrease due to increase of eff nuclear charge
but at end, repulsion between electrons increases radii increase
Prof. Myeong Hee Moon
8.4
physical properties: sizes, m.p.
• lanthanide contraction: 3rd transition (6th period)
• melting point: metal-metal bond: higher m.p. for elements with: 3 transition (6 period)
atomic radii of 3rd tran. are not muchdifferent from 2nd (4d, 5th period) tran.due to diffused f orbital poor screening
g pmore unpaired electrons
- # covalent bond characters
due to diffused f orbital.- poor screening
Prof. Myeong Hee Moon
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8.5
physical properties: hydration enthalpy
• enthalpy of hydration : energy change when a metal is hydrated.py y gy g y
M2+ (g) M2+ (aq)
Strength of the interactions increases as the ionic radii decrease allowing
predicted
as the ionic radii decrease, allowing water molecules to approach the ions more closely.
Exp data
-Deviations show that factors otherthan ionic radii are important.
t d f C M Z Exp data-note: no dev for Ca, Mn, Znhalf or full filled d orbital
Prof. Myeong Hee Moon
8.6
physical properties: oxidation statesof transition-metal elementsof transition metal elements
• higher ox state – relatively covalent, Mn2O7 (liq at rom temp)• lower ox. State – relatively ionic, Mn3O4 (m.p. 1564oC)
Prof. Myeong Hee Moon
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8.7
8.2 Bonding in simple molecules that containTransition Metals
1) Homonuclear diatomic molecules: formed at high temp in gas phase Cu Ag: formed at high temp in gas phase. Cu2, Ag2,
• two requirements to make diatomic moleculestwo requirements to make diatomic molecules- energy level order of tra.metals - ignor mixing of 4s orbital and 3d orbitals
psd 443 εεε <<23
zd
• typical overlap of 3d orbitals between two metals
ddand :*σσ
yzyzxzxz
zz
dddd
dd
−−
−
or and
and 22
:
:*ππ
σσ
xyxyyxyxdddd −−
−− or and 2222:*δδ
Prof. Myeong Hee Moon
8.8
MO formed from d-orbital overlap
and :*δδ
yxyx
dd
dd −−−
or
and
2222
:δδ
xyxy dd −
dddd or
and :*ππ
yzyzxzxz dddd −− or
22:*
zzdd −σσ and
Prof. Myeong Hee Moon
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8.9
Orbital correlation diagram for Homonuclear diatomic molecules of tr metals
C molec le stabe in gas phase [Ar]3d10 4s1 22 e for bonding• Cu2 molecule: stabe in gas phase. : [Ar]3d10 4s1. 22 e for bondingall orbitals filled except 4σ*. 2σ Filled with each 4s1.
B.O. = 1. single bond
Prof. Myeong Hee Moon
8.10
Heteronuclear diatomic molecules
• metal oxide
O in match or
O in match
nod
nod
xy
yx
nb
−
−− 22:δ
and xxz pd 23:* −ππ
y
or yyz pd 23 −
zzpd 23: 2
* −σσ and
Prof. Myeong Hee Moon
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8.11
Heteronuclear diatomic molecules
• ScO - (Sc: 4s2 3d1), (O:2s2 2p4) - total 9 electrons.t t (1 nb)2(2 )2(1 )4(3 nb)1 B O 3 ( i il t N )gr.state : (1σnb)2(2σ)2(1π)4(3σnb)1 B.O.=3 (similar to N2)
b i ith S 2+ (3d1) d O2 (2 2 2 6)• begin with Sc2+ (3d1) and O2-(2s2 2p6)
O 2s electrons ScO 1 σnb
O 2pz electrons contribute – 2σ orbitalsLigand-to-metal (L M) σ donationg ( )dative bond
Prof. Myeong Hee Moon
8.12
8.3 Introduction to Coordination Chemistry
• Formation of coordination complexes found by Werner: ti f C b lt h l id ( NH ) ith HCl( ): reaction of Cobalt chrloride (w NH3) with HCl(aq)
– NH3 was not removed. NH3 is bound: treated with AgNO3 at 0oC.
comp 1 : all Cl precipitated, comp2: 2/3 of Cl, comp3: 1/3, comp4:no primary valences (nondirectional) + secondary valences (well defined)
coordination complexes
Comp 1: CoCl3·6NH3 (orange-yellow) [Co(NH3)6]3+ Cl-3Comp 1: CoCl3 6NH3 (orange yellow) [Co(NH3)6] Cl 3
Comp 2: CoCl3·5NH3 (purple) [Co(NH3)5 Cl]2+ Cl-2Comp 3: CoCl3·4NH3 (green) [Co(NH3)4 Cl2]+ Cl-
Comp 4: CoCl ·3NH (green) [Co(NH ) Cl ]Comp 4: CoCl3 3NH3 (green) [Co(NH3)3 Cl3]
• Central metal atom – transition metal. Coordinate covalent bond
Prof. Myeong Hee Moon
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8.13
Coordination complex
• Werner tested electrical conductivity[Co(NH ) ]3+ Cl- similar to conductivity of Al(NO )[Co(NH3)6]3 Cl 3 similar to conductivity of Al(NO3)3
[Co(NH3)5 Cl]2+ Cl-2 similar to conductivity of Mg(NO3)2
[Co(NH3)4 Cl2]+ Cl- similar to conductivity of NaNO3
[C (NH ) Cl ] l l t i l d ti it[Co(NH3)3 Cl3] very low electrical conductivityC.N. : 1~16, mostly 6, commonly as 2~4, 5
• Ligands: anion or neutral compound Lewis bases (e donors)Ligands: anion or neutral compound, Lewis bases (e donors)
H2O: or :NH3. [Cu(NH3)]2+ , [Fe(CN)6]3-
Bidentate : ethylenediamine (en),
chelates: polydentate ligands
Prof. Myeong Hee Moon
8.14
Coomon Ligands
Prof. Myeong Hee Moon
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8.15
chelates
Trisoxalatocopper(III) ion
Prof. Myeong Hee Moon
8.16
Oxidation states
Ex) Determine the oxidation state of the coordinated metal atom in each of the followingsin each of the followingsa) K[Co(NH3)2 (CN)4] b) Os(CO)5, c) Na[Co(H2O)3 (OH)3]
Pt(NH3)2 Cl2 [Pt(NH3)3Cl][Pt(NH3)Cl3][Pt(NH ) Cl] [PtCl ] [Pt(NH ) ][Pt(NH )Cl ][Pt(NH3)3Cl]2 [PtCl4] [Pt(NH3)4][Pt(NH3)Cl3]2
Prof. Myeong Hee Moon
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8.17
Naming Coordination Compounds
1. In a coordination complex, single word. name ligand (w numbers) first and metalname ligand (w numbers) first and metal.
2. Name the compound with positive ion first followed (w space) negative ion.) g[Pt(NH3)3Cl]Cl :triaminechloroplatinum chloride
3. Anionic ligands named by putting suffix –o. f t l li d h dnames of neutral ligands – unchanged
common names for water – aqua, NH3-amine, see Table4 di tri tetra penta -- (bis tris tetrakis pentakis -- for4. di, tri, tetra, penta (bis, tris, tetrakis, pentakis, for
complicated ligand)5. list ligands in alphabetical order 6. A Roman numeral placed after the metal – oxidation states
If complex ion – negative : put –ate at the metal.
Prof. Myeong Hee Moon
8.18
Sample problem
Name the following coordination compounds:[Co(H2O)2Cl2]Cl diaquadichlorocobalt(III) chloride[Co(H2O)2Cl2]Cl diaquadichlorocobalt(III) chloride
K3[Fe(CN)6] potassium hexacyanoferrate(III)
Sodium hexafluorocobaltate(III) Na3[CoF6]Sodium hexafluorocobaltate(III) Na3[CoF6]
Bisethylenediaminecopper(II) chloride [Cu(en)2]Cl2
Prof. Myeong Hee Moon
Dithiosulfatoargentate(I) ethylenediaminetetraacetato calciate(II)
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8.19
Ligand Substitution Rxn
• Exchange of ligands : NH3 and Cl- in Weernewr’s cobalt complexes
NiSO ( ) 6 H O ( ) [Ni(H O) ] SO ( )
Yellow colorless Green
NiSO4(s) + 6 H2O (g) [Ni(H2O)6] SO4(s)
Yellow colorless Blue-violet
NiSO4(s) + 6 NH3 (g) [Ni(NH3)6] SO4(s)
green colorless Blue-violet
[Ni(H2O)6]2+(aq) + 6 NH3 (g) [Ni(NH3 )6]2+(aq) + 6 H2O
green colorless Blue-violet
• Chelate effect[C (H O) ]2+ 4NH [C (NH ) ]2+ 4H O K 4 108[Cu(H2O)4]2+ + 4NH3 → [Cu(NH3)4]2+ + 4H2O K=4x108
[Ni(NH3)6]2+ + 3en → [Ni(en)3]2+ +6NH3
Chelate effect (entropy) K 5x109
Prof. Myeong Hee Moon
Chelate effect (entropy) K=5x109
8.20
8.4 Structures of Coordination Complexes
•[Co(NH ) ]3+ structure ?•[Co(NH3)6]3+ structure ?
• CN = 2 – linear complex, 180op ,
• CN = 4 – tetrahedral complex, 109op– square planar complex (nd8electron configuration),
90o bond angles.CN 6• CN = 6 – octahedral complex, 90o bond angles.
Prof. Myeong Hee Moon
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8.21
CN = 4
Tetrahedral Square planar2
eg) Zn(NH3)42+, CoCl4
2- cf) VSEPR Modeleg) Cu(NH3)4
2+, Ni(II), Pd(II), Pt(II)
Prof. Myeong Hee Moon
tetraaminezinc(II) tetraamineplatinum(II)
8.22
Sample Problem
Predict the geometry of the following complexes:
[Ni(NH3)6]2+ [Pt(NH3)2 Cl2][Au(CN)2]+ CN 6 h d l[ ( )2] CN = 6, octahedral
CN = 4, square planar[Ni(NH3)6]2+
[Pt(NH3)2Cl2]CN = 2, linear
[Pt(NH3)2Cl2]
[Au(CN)2]+
Prof. Myeong Hee Moon
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8.23
Geometric Isomers - Oh
Cis-[Co(NH3)4Cl2]+ and trans- [Co(NH3)4Cl2]+
Prof. Myeong Hee Moon
8.24
Structural isomers
fac-triaminetrichlorocobalt(III)
Prof. Myeong Hee Moon
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8.25
Chiral Structures(optical isomerism)(optical isomerism)
Prof. Myeong Hee Moon
8.26
Optical isomers
All i [C (NH ) (H O) Cl ]+
Prof. Myeong Hee Moon
All cis-[Co(NH3)2(H2O)2Cl2]+
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8.27
Co-EDTA : chiral complex
Prof. Myeong Hee Moon
8.28
Ionization Isomers
Prof. Myeong Hee Moon
pentaaminesulfatocobalt(III) chloride pentaaminechlorocobalt(III) sulfate
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8.29
Coordination (sphere) isomers
T t i l ti (II) t t hl t (II)Tetraamineplatinum(II) tetrachlorocuprate(II)
Prof. Myeong Hee Moon
pentaaminenitrocobalt(III) aminepentanitrochromate(III)
8.30
Coordination complexes ion Biology
• 9 essential transition elements in life : V Cr Mn Fe Co Ni Cu Zn Mo: V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Mo
BacteriochlorophyllHemoglobin : carries 4 hemes.
Bacteriochlorophyll: related to photosynthesis
Prof. Myeong Hee Moon
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8.31
8.5 Crystal field theory: optical and magnetic p.
• Why does Ni(II) form octahedral, square-planar, tetrahedral complexes ?crystal field splitting theory (CFST)y p g y ( )
: explains electronic, optical, & magnetic propertiesbased on the interaction between metal – ligand
: In the presence of ligands,
- the d orbital of the metal are split by a slight energy difference ∆by a slight energy difference, ∆o
- electron in two orbitals
222 &zyx
dd−
experiences strong repulsion
with electrons from ligand
i i th f bit l
y
raising the energy of orbitals
Prof. Myeong Hee Moon
8.32
Crystal Field Modely
Approach of six ligands to transition metal cation splits d orbitals into two sets of different energy: explain color and magnetic propertiessets of different energy: explain color and magnetic properties
eg
E d
x2−y2 , dz2
ΔoΔo
dxy , dyz , dxz
3/5△o
2/5△o
Free metal ion in Spherical field in Oh fieldt2g
Free metal ion in Spherical field in Oh fieldsmall Δo large Δo
•Cristal field splitting energy Δ Cristal Field Stabilization Energy
Prof. Myeong Hee Moon
•Cristal field splitting energy Δo , Cristal Field Stabilization Energy
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8.33
high spin vs low spin
Cr3+: d3 paramagneticMn3+: d4 two gr states
• when Δ0 large: low spin comp.strong field
Mn : d two gr. states
strong field• when Δ0 small: high spin comp.
weak fieldweak field
Prof. Myeong Hee Moon
8.34
CFSE
• crystal field stabilization energy (CFSE)
Prof. Myeong Hee Moon
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8.35
SN=4, square planar vs. tetrahedral
Prof. Myeong Hee Moon
8.36
Magnetic Properties
• Ferromagnetism, Paramagnetism, Diamagnetism
Strong field Weak fieldHund’s Rule, strong paramagnetic
Prof. Myeong Hee Moon
Hund s Rule, strong paramagnetic
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8.37
Magnetic Properties
• Ferromagnetism, Paramagnetism, Diamagnetism
Prof. Myeong Hee Moon
8.38
8.6 Optical Properties & Spectrochemical Series
• colors: by ox state of metal, # & nature of ligand, geometry of complex.
Strong Field Ligand vs Weak Field LigandStrong Field Ligand vs. Weak Field Ligand
[Co(H2O)6]2+
[CoCl4]2-
Prof. Myeong Hee Moon
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8.39Effect of Ligands onthe Colors of Coordination Compoundsp
Spectrochemical series : the nature of the ligand determines the magnitude of the crystal field splitting, ∆omagnitude of the crystal field splitting, ∆o
: small size halide approaches metal more closely greater repulsion
I- < Br- < Cl- < F- < OH- < H2O < NH3 < NCS- < N < H3en < CO, CN-
weak field intermediate strong-field ligand (low spin)
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8.40
Absorption wavelengths
Prof. Myeong Hee Moon
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8.41
8.7 Bonding in Coordination Complexes
• hybrid orbitals
dsp3 : PF5
d2sp3: SF6
Prof. Myeong Hee Moon
8.42
• Hybrid orbitals
Prof. Myeong Hee Moon
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8.43
Orbital CorrelationDiagram of [CrCl ]-3Diagram of [CrCl6]-3
Cr
6Cl-
Cr
Prof. Myeong Hee Moon
8.44
Homework
10, 11, 12, 13, 14, 18, 22, 24, 33, 34, 36, 44
Prof. Myeong Hee Moon