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Molecular Examples

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Coordination Number 2

The linear [Ag(NH3)2]+ ion


Although [Ag(en)]ClO4 involves a normally bidentate ligand, in this case the structure is polymeric and the silver ion still retains a CN=2 with the N atoms (from different ligands) at ~180 degrees to each other.


Coordination Number 3

Trigonal planar - D3h

[Cu(CN)3]2-

 

[Cu(PPh3)2Br]


To help view more easily, the H atoms are turned off.
 

Trigonal pyramid

T-shaped

[Rh(PPh3)3]+


To help view more easily, the H atoms are turned off.

Coordination Number 4

Tetrahedral

Copyr2Cl2


Square Planar

cisplatin - cis-Pt(NH3)2Cl2


The cis- isomer is a powerful anti-cancer drug whereas the trans- is inactive.

Coordination Number 5

Square pyramid

Trigonal Bipyramid

[Ni(CN)5]3-


Coordination Number 6

Hexagonal planar

Trigonal prism

tris(cis-1,2-diphenylethene-1,2-dithiolato)rhenium


The ReS6 geometry is perfectly trigonal prismatic.

Octahedral

Hexol


The first 'truly' inorganic complex to be resolved into its optical isomers.

[Co(en)3]Cl3

mirror images

The classic example of optical isomerism in octahedral coordination complexes (H atoms not shown).

[Co(NH3)5CO3]+


Coordination Number 7

Capped octahedron (C3v)

K3[NbOF6]

Capped trigonal prism (C2v)

[V(III)(Hedta)(H2O)]H2O


Pentagonal Bipyramid (D5h)

bis-(tert-butylacac)2(DMSO)di-oxoUranium


The UO7 geometry fits a pentagonal bipyramid.

Coordination Number 8

Dodecahedron (D2d)

Zr(acac)2(NO3)2



[Zr(C2O4)4]4- is reported to have this shape as well.

Cube (Oh)

Square antiprism (D4d)

U(acac)4


Hexagonal bipyramid (D6h)

UO2(OAc)3


Coordination Number 9

Three-face centred trigonal prism (D3h)

Hydrated salts of the lanthanide elements eg Eu(H2O)9]3+


Coordination Number 10

Bicapped square antiprism (D4d)

Tetrakis(nitrato-O,O')-bis(triphenylphosphine oxide) cerium(IV)



Another example is [Ce(NO3)5]2-

Coordination Number 11

All-faced capped trigonal prism (D3h)

This is not a common stereochemistry.
In aqua-(12-crown-4)-tris(nitrato-O,O')-cerium(III) (12-crown-4) solvate and (15-crown-5)-tris(nitrato-O,O')-cerium(III) the Cerium ion is 11 coordinate.


Coordination Number 12

cuboctahedron (Oh)

Ceric ammonium nitrate -(NH4)2Ce(NO3)6

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