Pengantar Kimia Koordinasi

Kimia Anorganik II

COMPOUNDS NOMENCLATURE[Co(NH3)3(NO2)3] Triamintrinitrokobalt (III)

[Pt(NH3)2Cl2] Diamindikloroplatina (II)

[Ni(DMG)2] Bisdimetilglioksimatonikel (II)

[Cr(NH3)6](NO3)3 Heksaminkromium (III) nitrat

[Co(NH3)5H2O]Cl3 Akuopentaminkobalt (III) klorida

[Pt(NH3)4NO2Cl](SO4)2 Tetraminkloronitroplatina (IV) sulfat

K3[Al(C2O4)3] Kalium trioksalatoaluminat (III)

NH4[Cr(NH3)2(NCS)4] Ammonium diamintetratiosianatokromat (III)

Ca2[Fe(CN)6] Kalsium heksasianoferrat (II)

d-Orbitals and Ligand Interaction(Octahedral Field)

Ligands approach metal

d-orbitals not pointing directly at axis are least affected (stabilized) by electrostatic interaction

d-orbitals pointing directly at axis are affected most by electrostatic interaction

The six negative charges are equally distributedin a sphere around the metal

Crystal Field Theory (CFT)

6Dq = 0.6 o 4Dq = 0.4 o

High Spin Vs. Low Spin (d1 to d10)Electron Configuration for Octahedral complexes of metal ion having d1 to d10 configuration [M(H2O)6]+n. Only the d4 through d7 cases have both high-spin and low spin configuration.

Electron configurations for octahedral complexes of metal ions having from d1 to d10 configurations. Only the d4 through d7 cases have both high-spin and low-spin configurations.

CFSE (Crystal Field Stabilization Energy)

n Konfiguration Unpair electron CFSE12345678910

t2g1 t2g2

t2g3

t2g3 eg1

t2g3 eg2

t2g4 eg2

t2g5 eg2

t2g6 eg2

t2g6 eg3

t2g6 eg4

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-4Dq-8Dq-12Dq-6Dq0Dq-4Dq + P-8Dq + 2P-12Dq + 3P-6Dq + 4P0Dq + 5P

Octahedral complexes, weak field ligand, high spin complexes

Octahedral, Tetrahedral & Square Planar

CF Splitting pattern for various molecular geometry

M

dz2dx2-y2

dxzdxy dyz

M

dx2-y2 dz2

dxzdxy dyz

M

dxz

dz2

dx2-y2

dxy

dyz

OctahedralTetrahedral Square planar

Pairing energy Vs. Weak field < PeStrong field > Pe

Small High SpinMostly d8

(Majority Low spin)Strong field ligandsi.e., Pd2+, Pt2+, Ir+, Au3+

Color Absorption of Co3+ Complexes

The Colors of Some Complexes of the Co3+ Ion

The complex with fluoride ion, [CoF6]3+, is high spin and has one absorption band. The other complexes are low spin and have two absorption bands. In all but one case, one of these absorptions is in the visible region of the spectrum. The wavelengths refer to the center of that absorption band.

Complex Ion Wavelength of Color of Light Color of Complex light absorbed Absorbed

[CoF6] 3+ 700 (nm) Red Green

[Co(C2O4)3] 3+ 600, 420 Yellow, violet Dark green

[Co(H2O)6] 3+ 600, 400 Yellow, violet Blue-green

[Co(NH3)6] 3+ 475, 340 Blue, violet Yellow-orange

[Co(en)3] 3+ 470, 340 Blue, ultraviolet Yellow-orange

[Co(CN)6] 3- 310 Ultraviolet Pale Yellow

Colors & How We Perceive it

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Artist color wheelshowing the colors whichare complementary to oneanother and the wavelengthrange of each color.

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Black & White

If a sample absorbs all wavelength of visible light, none reaches our eyes from that sample. Consequently, it appears black.

When a sample absorbs light, what we see is the sum of the remaining colors that strikes our eyes.

If the sample absorbs novisible light, it is white or colorless.

Absorption and Reflection

If the sample absorbsall but orange, thesample appears orange.

Further, we also perceive orange color when visible light of all colors except blue strikes our eyes. In a complementary fashion, if the sample absorbed only orange, it would appear blue; blue and orange are said to be complementary colors.

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Light absorption Properties of Metal Complexes

Recording the absorption Spectrum

Complex Influence on Color

Compounds of Transition metal complexes solution.

[Fe(H2O)6]3+

[Co(H2O)6]2+

[Ni(H2O)6]2+

[Cu(H2O)6]2+

[Zn(H2O)6]2+

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Determine the field strength by measuring absorbed energy

Absorbancy

wavelength max

chE .

Absorded energy is energy used for exitation or the electrons from t2g to tg

Spectrophotometry method

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TEORI ORBITAL MOLEKUL

• Graphically these two orbitals look like this:

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Constructive Overlapof two 1s orbitals

Destructive Overlap of two1s orbitals

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Bonding orbital Anti-bonding orbital

Lower energy Higher energyStable UnstableFavorable for electrons Unfavorable for electronsElectrons exist between nuclei Electrons exist outside

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• Energetically, the molecular orbitals split.1. The 1s lies lower in energy.2. The 1s

* is higher in energy.

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• The head-on overlap of two corresponding p atomic orbitals on different atoms, such as 2px with 2px, produces:

1. bonding orbital

2. antibonding orbital

x2p*σ

x2pσ

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• Graphically, these orbitals look like this:

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• Graphically these orbitals look like this:

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1s 1s

1s

*1s

2s 2s

2s

*2s

2p 2p2px

*2px

2py 2pz

*2py

*2pz

N N

7 electrons + 7 electrons

Orbital Molekul [Co(NH3)6]3+

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Orbital Molekul [CoF6]3-

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