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Chapter 9 Coordination Chemistry I: Structures and Isomers

123

CHAPTER 9: COORDINATION CHEMISTRY I: STRUCTURES AND ISOMERS 9.1

Hexagonal:

C2v

C2v

D2h

Hexagonal pyramidal:

Cs

Cs

C2v

Trigonal prismatic:

Cs

C2v

C2

Trigonal antiprismatic:

Cs

C2

C2h

The structures with C2 symmetry would be optically active. 9.2

a.

dicyanotetrakis(methylisocyano)iron(II) or dicyanotetrakis(methylisocyano)iron(0)

b.

rubidium tetrafluoroargentate(III) or rubidium tetrafluoroargentate(1–)

c. cis- and trans-carbonylchlorobis(triphenylphosphine)iridium(I) or cis- and transcarbon ylchlorobis(triphenylphospine)iridium(0)

9.3

d.

pentaammineazidocobalt(III) sulfate or pentaammineazidocobalt(2+) sulfate

e.

diamminesilver(I) tetrafluoroborate(III) or diamminesilver(1+) tetrafluoroborate(1–) – (The BF4 ion is commonly called “tetrafluoroborate.”)

a.

tris(oxalato)vanadate(III) or tris(oxalato)vanadate(3–)

b.

sodium tetrachloroaluminate(III) or sodium tetrachloroaluminate(1–)

c. carbonatobis(ethylenediamine)cobalt(III) chloride or carbonatobis(ethy lenediamine)cobalt(1+) chloride

9.4

d.

tris(2,2-bipyridine)nickel(II) nitrate or tris(2,2-bipyridine)nickel(2+) nitrate (The IUPAC name of the bidentate ligand, 2,2-bipyridyl may also be used; this ligand is most familiarly called “bipy.”)

e.

hexacarbonylmolybdenum(0) (also commonly called “molybdenum hexacarbonyl”). The (0) is often omitted.

a.

tetraamminecopper(II) or tetraamminecopper(2+)

b.

tetrachloroplatinate(II) or tetrachloroplatinate(2–)

c.

tris(dimethyldithiocarbamato)iron(III) or tris(dimethyldithiocarbamato)iron(0)

d.

hexacyanomanganate(II) or hexacyanomanganate(4–)

e.

nonahydridorhenate(VII) or nonahydridorhenate(2–) (This ion is commonly called “enneahydridorhenate.”)

Copyright © 2014 Pearson Education, Inc. 

124 9.5

Chapter 9 Coordination Chemistry I: Structures and Isomers a.

triamminetrichloroplatinum(IV) or triamminetrichloroplatinum(1+)

b.

diamminediaquadichlorocobalt(III) or diamminediaquadichlorocobalt(1+)

c.

diamminediaquabromochlorocobalt(III) or diamminediaquabromochlorocobalt(1+)

d.

triaquabromochloroiodochromium(III) or triaquabromochloroiodochromium(0)

e. or

dichlorobis(ethylenediamine)platinum(IV) or dichlorobis(ethylenediamine)platinum(2+) dichlorobis(1,2-ethanediamine)platinum(IV) or dichlorobis(1,2ethanediamine)platinum(2+)

f. diamminedichloro(o-phenanthroline)chromium(III) or diamminedichloro(ophenanthroline)chro mium(1+) or diamminedichloro(1,10-phenanthroline)chromium(III) or diamminedichloro(1,10-phenanthroline)chromium(1+) g. or

bis(2,2-bipyridine)bromochloroplatinum(IV) or bis(2,2bypyridine)bromochloroplatinum(2+) bis(2,2-bipyridyl)bromochloroplatinum(IV) or bis(2,2bipyridyl)bromochloroplatinum(2+)

h. dibromo[o-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(II) or dibrom o[o-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(0) or dibrom o[1,2-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(II) or dibrom o[1,2-phenylene(dimethylarsine)(dimethylphosphine)]rhenium(0) i. dibromochlorodiethylenetriaminerhenium(III) or dibrom ochlorodiethylenetriaminerhenium(0) or dibromochloro(2,2diam inodiethylamine)rhenium(III) or dibromochloro(2,2diam inodiethylamine)rhenium(0) 9.6

9.7

a.

dicarbonylbis(dimethyldithiocarbamato)ruthenium(III) or dicarbonylbis(dimethyldithiocarbamato)ruthenium(1+)

b.

trisoxalatocobaltate(III) or trisoxalatocobaltate(3–)

c.

tris(ethylenediamine)ruthenium(II) or tris(ethylenediamine)ruthenium(2+)

d.

bis(2,2-bipyridine)dichloronickel(II) or bis(2,2-bipyridine)dichloronickel(2+)

a.

Bis(en)Co(III)-µ-amido-µ-hydroxobis(en)Co(III)

N N

Co N

4+

N

N H2 N O H

Co

N N

N

Copyright © 2014 Pearson Education, Inc. 

Chapter 9 Coordination Chemistry I: Structures and Isomers b.

125

Diaquadiiododinitritopalladium(IV) I ONO

H2O

Pd

H2O

ONO

ONO

ONO

H 2O

I

I

I OH2

ONO

OH2

H 2O

OH2 I

ONO I

I I

I

Pd

ONO

ONO

Pd

I

H 2O

I

Pd

I

Pd

ONO

OH2

ONO

ONO

OH2

Pd

ONO

OH2

H2O

enantiomers

c.

Fe(dtc)3

S S S

S

Fe

S

S

S

S

Fe

S S

S

S =

C

–

N

S S

S

CH3

H

S

At low temperature, restricted rotation about the C—N bond can lead to additional isomers as a consequence of the different substituents on the nitrogen. These isomers can be observed by NMR.

Copyright © 2014 Pearson Education, Inc. 

126 9.8

Chapter 9 Coordination Chemistry I: Structures and Isomers a.

triammineaquadichlorocobalt(III) chloride +

H2O H3N H 3N

Co

Isomers are of the cation: +

Cl

Cl

H3N

NH3

H3N

Co

OH2

H2O

NH3

Cl

Co Cl

Cl

Cl

cis

trans mer

b.

H3N

O

Cr

NH3

H3N

4+

NH3

H3N H3N

H3N

c.

fac

-oxo-bis(pentammine-chromium(III)) ion

Cr NH3

NH3 NH3

potassium diaquabis(oxalato)manganate(III) –

O O H2O

Mn

O

O

O

O

H2O

Mn

Isomers are of the anion:

–

O

–

H2O

O

O

OH2

O

OH2

O

H2O

trans

Cl

a.

O

Mn

cis enantiomers

9.9

NH3

cis-diamminebromochloroplatinum(II)

Pt Br

NH3 I

b.

diaquadiiododinitritopalladium(IV)

H2O

Pt

ONO

ONO OH2

I

c.

tri--carbonylbis(tricarbonyliron(0))

O C

O O C C Fe OC

+

NH3

O C CO Fe

CC O O

Copyright © 2014 Pearson Education, Inc. 

CO

NH3 NH3

Chapter 9 Coordination Chemistry I: Structures and Isomers O

9.10 C

CH2

O –

H2 N O N

= N

O

O

M

O

N

N

O

O

N

M

N

N

O

O

N

N

M

N

N

N

O

O

N

O

mer

M(AB)3 B A

B

M

B

A

A

B

B

A

M

A

A

B

B

A

A

M

A

A

A

B

B

A

B

mer

[Pt(NH3)3Cl3]+

a.

B

M

B

fac

9.12

O

M

O

fac

9.11

127

+

NH 3 Cl

Pt

Cl

+

Cl

NH3

H3N

NH3

Cl

NH3

Pt

NH3

Cl

Cl

fac

mer

[Co(NH3)2(H2O)2Cl2]+

b.

+

NH3 H 2O Cl

Co

+

Cl

NH3

H 2O

OH2

H 2O

Cl

Co

NH3

Cl

NH3

Cl

+

OH2

Cl

Co

Co

Cl

OH2

H2 O

NH3

H 3N

NH3

H3N

Cl

Co

Co NH3

+

H 2O OH2 Cl

Cl

enantiomers

Copyright © 2014 Pearson Education, Inc. 

+

NH3

OH2

NH3

Cl

H 2O

+

NH3

OH2 Cl

128

Chapter 9 Coordination Chemistry I: Structures and Isomers [Co(NH3)2(H2O)2BrCl]+

c.

+

OH2 H 3N H 3N

Co

Br

H 2O

Cl

H 2O

Co

OH2

+

Br

Co

NH3

Br

NH3

Cl

Co

+

H 3N

NH3

H 3N

Cl

OH2

Cl

OH2

H2 O

H2 O

Co

Cl

Br

+ NH3

H3 N

NH3

H3N

+ OH2

Co

Cl

Br

enantiomers

d.

Br

H2O

Br

Cl

OH2

Co NH3

OH2

OH2

Co

+

NH3

NH3

H2O

NH3

+

NH3

Br

OH2 H 2O

+

Cl

enantiomers

Cr(H2O)3BrClI OH2 H2 O

H2O OH2

Cr

Cl

H2 O

I

OH2

Cr

I

Br

Cl

Br

enantiomers

Cl H2 O

Cr

OH2

I H 2O

Br

Cr

OH2

Cl

Br

H2 O

OH2

Cr

I

Br

Cl

I

e.

OH2

OH2

OH2

[Pt(en)2Cl2]2+ 2+

N N Cl

Pt

2+

N

N

N

N

N

Cl

Pt

N Cl

Cl

cis enantiomers

Copyright © 2014 Pearson Education, Inc. 

2+

Cl N N

Pt Cl

trans

N N

Chapter 9 Coordination Chemistry I: Structures and Isomers [Cr(o-phen)(NH3)2Cl2]+

f.

+

N Cl

NH3

H 3N

NH3

H3N

N

N

Cr

N

trans NH3 ligands

2+ 2+

Br

2+

N

N

N

N

N

N

Pt

Cl

Cl

Cl

trans Cl ligands

[Pt(bipy)2BrCl]2+

Pt

H3N

NH3

NH3

Cr

NH3

enantiomers

N

N

Cl

Cr

Cl

Cl

Cl

Cl

N

N

N

Cr

+

+

+

N

g.

129

Br

Br

Cl

Cl

N

Pt

N N

N

enantiomers

h.

Re(arphos)2Br2

Abbreviating the bidentate ligands As P :

Br P As

Re

Br P

P

As

As

Re

Br

Br

Re

As

Br

P

Br

Br

P

P

P

P

Re

Re

P As

As

As

As

P

As

As Br

P

Br

Br

Br

Br



P 

As

As

Re

As

As

P







Copyright © 2014 Pearson Education, Inc. 

Re

P As

P As

Re P 

Br Br

Br Br

130

Chapter 9 Coordination Chemistry I: Structures and Isomers i.

Re(dien)Br2Cl Cl N

Re

N

Br

Cl Br

Br

Br

Br

Re

N

N

N

N

N

Br

N

Cl

Re

Cl

N

N

N

Br

Re

Br

9.13

Br

N

N

N

Cl

Re

N

Br

a. M(ABA)(CDC) C A

A

M

B

D

C

A

D

B

M

C

B

C

A

D

C

B

M

A

A

A

A

M

C

C

b. M(ABA)(CDE) C A B

M

D

C

A

D

E

C D

C D

    

      

A

A M

B

B

A

A

M

E

E

B

B

M

A

A

A

A

M

E

E

A

A

M E

A

A

B

B

M E

Copyright © 2014 Pearson Education, Inc. 

C D

C D

C D

 

C D

Chapter 9 Coordination Chemistry I: Structures and Isomers

131

9.14 A

A C B

M

B

A

C

B

M

B

A B

                  9.15

B

C

C

M

B

B

C

C

A B

C

A

A M

B

C

A

A

A

C

M

A

A

B

B

C

M

A

A

B

B

M

C

C

C

C

B

B

B

B

M

C

C

A

B

M

A

A

B

B

M

C

C

A

A

C

C

M

C

A B

A B

C

 

a. The “softer” phosphorus atom bonds preferentially to the soft metal Pd (see Section 6.6.1). b, c. Abbreviating the bidentate ligands N P : Cl P N

Ni

Cl P

P

N

N

Ni

Cl

Cl

Ni

N

Cl

P

Cl

Cl

N Cl

P

P

P

P

Ni

N

N

N

N

P

N P

Ni

P

Cl

Cl

Cl

Cl

Ni



P 

N

N

Ni

N

N

P







Copyright © 2014 Pearson Education, Inc. 

P

P

N

N

Ni P 

Cl Cl

Cl Cl

132

9.16

Chapter 9 Coordination Chemistry I: Structures and Isomers

a, b.

Abbreviating the bidentate ligands N P and O S : Cl S O

N Cl Cl

M

P

P

O

O

Cl

P

S

N

O

M

Cl

Cl

N

P

M

Cl

Cl

Cl

Cl

M

N P

P N

N

O

O

M



S 



S 

N

N

P

P

S

Cl

M

Cl

M

P

P

S

S

M

S

Cl

Cl

Cl

Cl

M

N

N

S

S

M

O

O

O

O









Cl Cl

Cl Cl

–

N

9.17

The single C–N stretching frequency indicates a trans structure for the cyanides (the symmetric stretch of the C—N bonds is not IR active), while the two C–O bonds indicate a cis structure for the carbonyls (both the symmetric and antisymmetric C–O stretches are IR active). As a result, the bromo ligands are also cis.

C O

C Br

Co C N

Copyright © 2014 Pearson Education, Inc. 

O

C Br

Chapter 9 Coordination Chemistry I: Structures and Isomers 9.18

There are 18 isomers overall, six with the chelating ligand in a mer geometry and 12 with the chelating ligand in a fac geometry. All are enantiomers. They are all shown below, with dashed lines separating the enantiomers. N P

M

As

P

P

Br

Br

OH2

H2O

N

N P

M

P

As

M

As

Br

Br

NH3

H 3N

N P

M

N

N

N

N

N

OH2 Br

H2O

P

M

Br

P

As

As

H3 N

NH3

M

Br

Br

P

M

As

H 2O

NH3

H3N

M

OH2

Br

Br

NH3

NH3

OH2

OH2

NH3

NH3

N OH2

N

P

M

H2O

P

As

Br

N

N

M

As



1.        Mo

O

2. 

O

S

Mo

OH2

 

Cs

       S Mo

S

   

O

S Mo

O

Mo

Cr W

Mo

Mo

O Cr

       C1

O

Se

C1

O S

O

Mo

S

S

Mo

O

W

 

Cr W

Se

C1

O Mo

Cr W

S

Se

Se

O

Mo

C1

O O

W

Mo

Cr

C1

Se

   

 

W

Cs 

       C1

S

O

O

W

Mo

Mo

Mo

O

Cr Se

O

Mo



S

Mo

Mo

Mo

Se Cr

O Se

O W

C1

Copyright © 2014 Pearson Education, Inc. 

O

Mo Cr

W

C1

M OH2

 

S Mo

W

N Br

O W

Mo

Mo

3. 

Mo

O

N Br

Mo

O

O

M

As

O

   Cs                         C3v 

S

 

S Mo

W

d.



Mo

O

Mo

 

c.



P

As

Br

Br

b.

P

M

H3N

NH3

a, b.

   

As

OH2

OH2

9.22

   

M

NH3

20b  20c top ring: , bottom ring: 

 

P

NH3

9.21

 

M

N

All are chiral if the ring in b does not switch conformations.

   

H2 O

Br

9.20

 

H3N

Br

a.

 

NH 3 OH2

OH2

9.19

 

M

As

OH2

Br

   

P

As

N

NH3

M

As

N

NH3

M

As

   

133

S

 

P As

P As

P As

134

Chapter 9 Coordination Chemistry I: Structures and Isomers

S Mo

Mo Mo

Cr

     

9.23

S

Se O

Mo Se

W

W O             O       Cs                                                        Cs 

O

   

   

c.   

Yes, provided the structure has no symmetry or only Cn axes. Examples are the structures with C1 symmetry in part a.

Cr

 

The 19F doublet is from the two axial fluorines (split by the equatorial fluorine). The 19F triplet is from the equatorial fluorine (split by the two axial fluorines). The two doubly bonded oxygens are equatorial, as expected from VSEPR considerations. Point group: C2v

9.24

+

F O O

Os

F

F

Examples include both cations and anions: –

–

–

–

–

[Cu(CN)2] , [Cu2(CN)3] , [Cu3(CN)4] , [Cu4(CN)5] , [Cu5(CN)6]

[Cu2(CN)]+, [Cu3(CN)2]+, [Cu4(CN)3]+, [Cu5(CN)4]+, [Cu6(CN)5]+ Based primarily on calculations (rather than experimental data), Dance et al. proposed linear structures such as the following: –

[Cu(CN)2] :

NC—Cu—CN

–

NC—Cu—CN—Cu—CN

–

NC—Cu—CN—Cu—CN—Cu—CN

[Cu2(CN)3] : [Cu3(CN)4] : +

[Cu2(CN)] :

Cu—CN—Cu

+

Cu—CN—Cu—CN—Cu

+

Cu—CN—Cu—NC—Cu—CN—Cu

[Cu3(CN)2] : [Cu4(CN)3] :

Where 2-coordinate copper appears in these ions, the geometry around the Cu is linear, as expected from VSEPR. 9.25

The bulky mesityl groups cause sufficient crowding that the phosphine ligands can show HC chirality (C3 symmetry) and can be considered as similar to left-handed (PL) and right-handed (PR) propellers. If two P(mesityl)3 phosphines are attached in a linear arrangement to a gold atom, three isomers are possible: 3

PL—Au—PL

PR—Au—PR

PL—Au—PR

H 3C

mesityl

(PR—Au—PL is equivalent to PL—Au—PR, as can best be seen with models.) NMR data at low temperature support the presence of these isomers, which interconvert at higher temperatures.

Copyright © 2014 Pearson Education, Inc. 

CH3

Chapter 9 Coordination Chemistry I: Structures and Isomers 9.26

The point group is D3h. A representation  based on the nine 1s orbitals of the hydride ligands is: D3h  A1 E A2 E

E 9 1 2 1 2

2C3 0 1 –1 1 –1

3C2 1 1 0 –1 0

2S3 0 1 –1 –1 1

h 3 1 2 –1 –2

3v 3 0 0 1 0





 Re

 z2 (x, y), (x2–y2, xy) z (xz, yz)

135

 





 = H

The representation  reduces to 2 A1 + 2 E + A2 + ECollectively these representations match all the functions for s (totally symmetric, matching A1), p, and d orbitals of Re, so all the s, p, and d orbitals of the metal have suitable symmetry for interaction. (The strength of these interactions will also depend on the match in energies between the rhenium orbitals and the 1s orbital of hydrogen.) 9.27 NN

NN

NN

O Cr O

O Cr O

O Cr O

O Mn O O O

OO

OO

OO

OO

O Mn O O O O O

OO

OO

OO O Mn O O O O O

O O Mn O

OO

O

O Cr O

O Cr O

O Cr O

NN

NN

NN

9.28

N

N N

N N O O

O O

N

N

N

N

N

O

N

N N

Co O O

N Co

N

O O

Co O

O O N

N

N

N N O O N

Co

N O

O O

N

N

O

O O N

N

N

N

N

N

Co O O

N

N Co

O O N

N

N

N

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136 9.29

9.30

Chapter 9 Coordination Chemistry I: Structures and Isomers a.

Cu(acacCN)2: D2h

b.

C6

tpt: C2v

All four metal-organic frameworks studied (MOF-177, Co(BDP), Cu-BTTri, Mg 2 (dobdc) ) are significantly more effective at adsorbing carbon dioxide relative to adsorbing hydrogen. This is attributed, in part, to the higher polarizability of CO 2 relative to that of H 2 . The formation of an induced dipole in these gases by exposed cations within MOFs is an important prerequisite for adsorption. The two MOF properties that most strongly correlate with CO 2 adsorption capacity are MOF surface area and MOF accessible pore volume. As these values (tabulated below) increase, the CO 2 adsorption capacity increases. MOF

Surface Area ( m2 g )

Accessible Pore Volume ( cm3 g )

MOF-177

4690

1.59

Co(BDP)

2030

0.93

Cu-BTTri

1750

0.713

Mg 2 (dobdc)

1800

0.573

The graphs in Figure 1 of the reference clearly indicate that Mg 2 (dobdc) adsorbs the most CO 2 at 5 bar. The arrangement and concentration of open Mg 2+ cation sites on the Mg 2 (dobdc)

surface is hypothesized to render this MOF more susceptible to CO 2 adsorption. This MOF, along with Cu-BTTri, which also features exposed metal sites, are identified as the best prospects for CO 2 H 2 separation. 9.31

The synthesis and application of amine-functionalized MOFs for CO 2 adsorption is the general

topic of the reference. While the M 2 (dobdc) series of MOFs were proposed as excellent candidates for this functionalization (on the basis of their relatively large concentration of exposed metal cation sites), their amine-functionalization proved difficult. This was attributed to the relatively narrow MOF channels that may hinder amine diffusion into M 2 (dobdc) .

One hypothesized solution was to prepare a MOF with the M 2 (dobdc) structure-type, but with larger pores. The wider linker dobpdc (below, along with dobdc for comparison) was used in the hope of obtaining MOFs with larger pores. O

O O

O

O O

O

O O

O

O

O dobdc

dobpdc

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Chapter 9 Coordination Chemistry I: Structures and Isomers

137

Amine-functionalized Mg 2 (dobpdc) was prepared by mixing H 4 (dobpdc) , magnesium bromide, and a small solvent volume (a mixture of N,N’-diethylformamide and ethanol) in a Pyrex container. The mixture was heated in a microwave reactor, and the M 2 (dobpdc) collected by

filtration after cooling. Dried samples of Mg 2 (dobpdc) were then heated for roughly one hour at

420 °C under dynamic vacuum. After this “activation” step, Mg 2 (dobpdc) was stirred with an excess of N,N’-dimethylethylenediamine (mmen) in hexanes for one day. Subsequent heating under vacuum resulted in removal of residual solvents to afford mmen-functionalized Mg 2 (dobpdc) . The “activation” step was found necessary to completely remove residual N,N’diethylformamide from the Mg 2+ coordination sites. 9.32

This reference discusses application of porphyrin-containing MOFs where the porphyrin provides a binding site for Fe(III) and Cu(II). The precursor to the porphyrin linker (TCPP) is provided below; the resulting carboxylates of this linker permit its incorporation into the MOF. HOOC

COOH

N H N

N H N

HOOC

COOH

The metallation options include premetallation and postmetallation. In premetallation, H 4 -TCPP-Cu and H 4 -TCPP-FeCl , respectively, are used as reactants for the MOF synthesis. In this case, the porphyrin linker and its bound metal ion are installed simultaneously into the MOF. This general approach afforded MOF-525-Cu, MOF-545-Fe, and MOF-545-Cu. MOF-525-Fe could not be obtained via this strategy. For this MOF, postmetallation was employed, via the reaction of MOF-525 with Fe(III) chloride; Fe(III) ions were introduced into the MOF-525 porphyrin linkers via this method. In terms of similarities and differences, MOF-545 can be metallated with both Fe(III) and Cu(II) via a premetallation strategy, while MOF-525 requires alternate procedures for incorporation of Cu(II) (premetallation) and Fe(III) (postmetallation), respectively.        

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