Iron Carbonyl Dianions Stabilized by the Indium tris(3,5-dimethyl)-1

Pyrazolylborate Moiety

Brandon Alexander

Chemistry Seminar

What’s a Pyrazolylborate?

BH

N N

N N

NN

-S. Trofimenko (DuPont)-Appeared 1966-Tridentate

-Can bind to a metal center with two donor sites like the pincers of a scorpion

-The third donor site reaches over the plane to bind to the final position created by the metal and the other two donor atoms

-Scorpionate Ligand (fac manor)

1-1

What’s a Pyrazolylborate?

-Why a pyrazolylborate?

• SynthesisBH

N N

N N

NN

-1

Types of Pyrazolylborates

• Bis(Pyrazolylborate)

BH

H

N N

N

N

• Tris(Pyrazolylborate)• Tetrakis(Pyrazolylborate

)

BH

N N

NN

N

N

B

N

N

N

NN

N

N

N

-1

-1

-1

Synthesis of PyrazolylborateKBH4 + H-pz

3-H2

~180 C

4-H2~220 C

~150 C

2-H2

BH

N

N

NN

N N

-1

(Ex)

“tris” ligandK[HB-pz3]

BH

H

N N

N

N

“bis” ligandK[H2B-pz3]

-1

“Tetrakis” LigandK[B-pz4]

B

N

N

N

NN

N

N

N

-1

Trofimenko, S. “Boron-Pyrazole Chemistry. II. Poly(1-pyrazolyl)borates” J. Amer. Chem. Soc. 1967, 89 , 3170.

Indium tris(3,5-dimethyl)-1Pyrazolylborate

• Adding the Metal Center

In

Cl

Cl

BH

N N

N N

NN

THF

3

4

5-R group selection

Adding the Metal CenterSynthesis

KL + InCl3 LInCl2 . THFTHF

+ KClL=tris ligand, [HB(Me2-pz)3]

BH

N

N

N N

N N

-1

Reger, et. al. Organometallics. 1994.

BH

N N

NN

N N In

Cl

Cl

THF

Indium Pyrazolylborate Indium Pyrazolylborate • Now we synthesized an Indium Pyrazolylborate

Now what?-Reactivity

BH

N N

NN

N N In

Cl

Cl

THF

•Can react with•Other pyrazolylborates

•Diethyldithiocarbamate•NaS2CN(C2H5)2

•Maleonitriledithiolate•MNT- (Na2S2C2(CN)2)

•Other R groupsReger, et. al. Organometallics. 1994.

Reacting the In-pz

• Create Metal-Metal bonds with In-pz and Metal Carbonyl(s)

• Metal Carbonyl Anions

(In-pz= Indium Pyrazolylborate)

Metal Carbonyls• Reger, et.al. explored metal-metal bonds

with two metal carbonyl complexes.

• Fe(CO)5

• W(CO)6

Fe

OC

OC

CO

CO

OC

W

OC

OC

CO

CO

OC CO

Reger, et. al. Organometallics. 1994.

Synthesizing the Metal Carbonyls into a [2-] Dianion

Fe

OC

OC

CO

CO

OC

Naphthalene

Na (s) +Fe

CO

OCCO

OC

-2

-CO

1.Collman, J.P. Accounts of Chemical Research. 342-347.

W

OC

CO

CO

OC CO

-2

W

OC

OC

CO

CO

OC CO Naphthalene

Na (s) +

Synthesizing the Metal Carbonyls into a [2-] Dianion

-CO

Stability of Metal Carbonyl Anions

• Metal Carbonyl Anions are light and extremely heat sensitive.

• React violently with the atmosphere and readily release carbon monoxide.

• Stored under Nitrogen environment

Bringing it all TogetherBringing it all Together• Selected Indium Pyrazolylborate has been

synthesized.• A set of [2-] metal carbonyl anions have been

synthesized

Fe

CO

OCCO

OC

-2

W

OC

CO

CO

OC CO

-2BH

N N

NN

N N In

Cl

Cl

THF

Bringing it all TogetherBringing it all Together• Reactivity of the Indium Pyrazolylborate and

the Metal Carbonyl Anions

• “One pot” reaction

Bringing it all Together“One Pot” Reaction

LInCl2. THF + Na2M(CO)x L-In-M-(CO)x

THF

-2NaCl

L = tris ligand, [HB(Me2-pz)3]

(M-CO)x = any [2- ]metal carbonyl

•Very High Molar Mass

•Not very soluble

Reger, et. al. Organometallics. 1994.

Final ProductFinal ProductShort Metal-Metal BondShort Metal-Metal Bond

• [(HB(Me2-pz)3]In-Fe(CO) 4

• “Shortest In-Fe bond to date”

2.463(2) Å

Reger, et. al. Organometallics. 1994.

Final ProductFinal ProductShort Metal-Metal BondShort Metal-Metal Bond

• [(HB(Me2-pz)3]In-W(CO) 5

• “First In-W bond to be structurally characterized”

2.783(2) Å

Reger, et. al. Organometallics. 1994.

Expanding the use of In-pz with one (or more) Metal Carbonyl Anions

• Strong, et. al. have developed a potential high yield & high purity synthesis of the [2-] dimer and trimer iron carbonyl from their neutral parents .

•Triiron Dodecacarbonyl•Diiron nonacarbonyl

Strong, H., et.al Inorganic Syntheses 28: 1990. 203–207.

Hierarchy

Diiron nonacarbonyl Fe2(CO)9

Triiron Dodecacarbonyl

Fe3(CO)12

Iron pentacarbonyl*

Diiron dianion [Fe2(CO)8]2-

Triiron dianion [Fe3(CO)11]2-

New Indium Pyrazolylborate--Iron Carbonyl Complexes

“One Pot” ReactionIndium tris(3,5-

dimethyl)-1 Pyrazolylborate

Synthesis of Diiron Nonacarbonyl

• Photolysis of Commercial Iron Pentacarbonyl

2Fe(CO)5 Fe2(CO)8 + 2 COhv

•Temperature Controlled to prevent decomposition

•High Yielding synthesis 90%+

IR Analysis

• Carbonyl Peaks are comparable to Commercially available spectra and spectra from

literature.

Sigma-Aldrich FT-IR

Synthesis of Triethylenediamine octacarbonylferrate[Fe(C2H4(NH2)2)3][(Fe2(CO)8]

6 C2H4(NH2)2 + 3 Fe2(CO)8 2[Fe(C2H4(NH2)2)3][(Fe2(CO)8] + 8 CO

•Following Heiber, et. al.

•2.5 g of commercial diiron nonacacarbonyl was treated with the molar eq. of ethylenediamine

Under nitrogen environment

Introduction of ethylenediamine caused a red-sludge like constancy to develop.

Release of CO—fog like.Heiber, W., et. al. Chem. Ber. 1957, 90. (2). 278-286. Translated.  Heiber, W., R. Werner.” Chem. Ber. 1957, 90. (2). 286-296. Translated.

After rinsing the crystals with water, filtering and drying

under vacuum crystals were red/orange in color.

Synthesis of Triethylenediamine octacarbonylferrate

Synthesis of ([Hydrotris[(3,5 dimethylpyrazolyl)borato]indium]octacarbonyl

diiron

[Fe(C2H4(NH2)2)3][Fe2(CO)8] + HB[(Me2-pz)3]InCl2 THFTHF

“One Pot” Reaction

BH

N N

NN

N N InFe

FeCO

CO

CO

COCO

OC

OC

COTHF

+ [Fe(C2H4(NH2)2)3]Cl2

[Fe(en)3][Fe2(CO)8]

1HNMR Results

• NMR spectroscopy of this compound provided an insight as to the structure of this compound.

• Comparing

BH

N N

NN

N N InFe

FeCO

CO

CO

COCO

OC

OC

COTHF

BH

N N

NN

N N In

Cl

Cl

THF

BH

N N

NN

N N In

Cl

Cl

THF

1HNMR (CD3SOCD3): δ 5.505, 5.137 (s,s, 2.87, 2.09; 4-H); 3.388, 2.162 (m-m 18.89, 20.39; THF), 2.706, 1.883, (s-s, 45.84, 44.32 Me), 1.507, 0.869, (s-s, Me 15.89, 8.49). The peaks at 5.505 and 5.137 ppm indicate the 4-H position on the Pyrazolyl rings, the peaks at 3.388 and 2.162 provide that a weakly bound THF solvent ligand is attached, keeping the indium octahedral, the peaks at 2.706 and 1.883 show the two equivalent methyl groups on two of the Pyrazolyl rings and the peaks at 1.507 and 0.869 show the nonequivelent methyl groups on the last Pyrazolyl ring.

Comparing these 1HNMR peaks to the ones for the initial Indium tris(3,5-dimethyl)-1 Pyrazolylborate: 1HNMR (CDCl3): HB[(Me2-pz)3]InCl2·THF δ5.97 (1.23, s, 4-Hpz*); 3.80, 1.90 (1.00, 1.90, m, m; THF); 2.60, 2.95 (7.10, 7.10,s,s; 3,5Me-pz*) the peaks have shifted, indicating that the Indium tris(3,5-dimethyl)-1 Pyrazolylborate has coordinated to the diiron complex. The two lone pair of electrons in the reduced state of the ethylenediamine dianion (one from each iron) has donated them to the central indium atom making a new coordination complex.

BH

N N

NN

N N InFe

FeCO

CO

CO

COCO

OC

OC

COTHF

Synthesis of Triethylenediamine undodecacarbonyl ferrate[Fe(C2H4(NH2)2)3][(Fe3(CO)11]

• Following Heiber, et. al.• 2.5 g of commercial triiron dodecacarbonyl was

treated with the molar eq. of ethylenediamineUnder nitrogen environment

Introduction of ethylenediamine caused a red-sludge like constancy to develop.

Release of CO—fog like.

Heiber, W., et. al. Chem. Ber. 1957, 90. (2). 278-286. Translated.  Heiber, W., R. Werner.” Chem. Ber. 1957, 90. (2). 286-296. Translated.

Synthesis of Triethylenediamine undodecacarbonyl ferrate

After rinsing the crystals with water, filtering and drying under

vacuum crystals were red to dark orange in color.

Synthesis of ([Hydrotris[(3,5 dimethylpyrazolyl)borato]indium] undodecacarbonyltriiron

“One Pot” Reaction

[Fe(C2H4(NH2)2)3][Fe3(CO)11] + HB[(Me2-pz)3]InCl2 THF

THF

BH

N N

NN

N N In Fe

Fe

Fe

CO

CO

CO

CO

OC

OC

COOC CO

CO

OC

+ [Fe(C2H4(NH2)2)3]Cl2

[Fe(en)3][Fe3(CO)11]

[HB(Me2-pz)3][Fe3(CO)11]

Gaussian Molecular Modeling

•Molecular Modeling Work using Gaussian can be used to predict gas phase IR

•Changing Basis Sets and Level Calculations

•Starting with Hartree-Fock and moving to Møller-Plesset (MP2, MP3, MP4), and progressively to Becke 3-Parameter (B3LYP)

•Starting with Basis Set 6-31,6-311G 6-311G* 6-311G**

•Starting with the tris(3,5-dimethyl) Pyrazolylborate and build structures with increasing complexity

Conclusions

• Two different ethylenediamine derivatives of iron carbonyl dianions have been synthesized and the synthesis of [Fe2(CO)8]2- was made by adopting the same procedure established by Heiber, et. al. for [Fe3(CO)11]2- .

• These derivatives are much easier to handle and spectra are easily obtainable

• Two new iron metal carbonyl complexes have been coordinated to the Indium tris(3,5-dimethyl)-1 Pyrazolylborate Moiety.

Conclusions

BH

N N

NN

N N In Fe

Fe

Fe

CO

CO

CO

CO

OC

OC

COOC CO

CO

OC

BH

N N

NN

N N InFe

FeCO

CO

CO

COCO

OC

OC

COTHF

Further Research• Gaussian Modeling to obtain gas phase IR

• X-Ray Crystal Structures

• 1HNMR of [HB(3,5-Me2-pz)3]In[Fe3(CO)11]

• Transmetalation of Indium tris(3,5-dimethyl)-1 Pyrazolylborate Moiety

• Synthesizing different transition-metal carbonyl dianions to complex to Indium tris(3,5-dimethyl)-1 Pyrazolylborate Moiety

Ellis, J. E. Organometallics. 2003,22, 3322-3338.

AcknowledgmentsMount Union College

Department of Chemistry

Dr. Scott Mason, Dr. Jeffery Draves, & Dr. Debra Boyd-Kimball

Dr. Mark Himmelein, Mount Union College, Department of Foreign Languages

Dr. Yan Sun, Case Western Reserve University

1.Trofimenko, S. “Boron-Pyrazole Chemistry. II. Poly(1-pyrazolyl)borates” J. Amer. Chem. Soc. 1967, 89 , 3170.

2.Reger, Daniel L.; Mason, Scott S.; Reger, Lance B.; Rheingold, Arnold L.; Ostrander, Robert L. “Synthesis and Characterization of Indium(III) Complexes Containing Two Different Chelate Ligands of the Type [Hydrotris(3,5-dimethylpyrazolyl)borate]In[ligand]X”. Inorganic Chemistry, 1994,33, 1811-1816.

3.Reger, D.L., Mason, S.S. , Rheingold, A.L., Ostrander, R.L. “Indium (III) Complexes of Potentially Tridentate Poly(pryazolyl)borate Ligands. Ionization of Molecular [HB(pz)3]InCl in CD2Cl2 Solution.” Inorganic Chemistry. 1994, 33 (9). 1803-1810.

4.Reger, D.L., Knox, S.J., Rheingold, A.L., Haggerty, B.S. “Indium (III) dihydrobis(pyrazolyl)borate complexes. Crystal and Molecular Structures of {[H2B(pz)2]In(CH3)Cl}2 and [H2B(pz)2]In(CH3)2.” Organometallics. 1990. 9 (9) . 2581-2587.

5.Reger, Daniel L.; Mason, Scott S.; Rheingold, Arnold L.; Haggerty, Brian S.; Arnold, Frederick P. “Syntheses and Solid State Structures of [HB(3,5-Me2pz)3]InFe(CO)4 and [HB(3,5-Me2pz)3]InW(CO)5 (pz = Pyrazolyl Ring). Intermetallic Complexes with Short

Metal-Metal Bonds.” Organometallics. 1994, 13, 5049-5053.

6.Collman, J.P. “Disodium Tetracarbonyl Ferrate—a Transition-Metal Analog of a Gringnard Reagent.” Accounts of Chemical Research.” 342-347.

7.Strong, H.; Krusic, P. J.; San Filippo, J. (1990). Robert J. Angelici. ed.. "Sodium Carbonyl Ferrate, Na2Fe(CO)], Na2[Fe2(CO)8], and Na2[Fe3(CO)11]. Bis[μ-Nitrido-Bis(triphenylphosphorus)(1+] Undecarcarbonyltriferrate(2-), [(Ph3P)2N]2[Fe3(CO)11]". Inorganic Syntheses 28: 1990. 203–207.

8.Heiber, W., et. al. “Über Metallcarbonyle. 79. Mitteil. Neuere Anschauungen Uber Entstehung und Konstitution Äthylendiamin-Haltiger Eisencarbonyle” Chem. Ber. 1957, 90. (2). 278-286. Translated.

9.Heiber, W., R. Werner. “Über Vierkernige Carbonyl Ferrate.” Chem. Ber. 1957, 90. (2). 286-296. Translated.

10. Ellis, J. E. Metal Carbonyl Anions:  from [Fe(CO)4];2- to [Hf(CO)6];

2- and Beyond. Organometallics. 2003,22, 3322-3338.

References