Third Osaka CityThird Osaka CityThird Osaka CityThird Osaka CityUniversity InternationalUniversity InternationalUniversity InternationalUniversity International

Symposium Symposium Symposium Symposium on Moleon Moleon Moleon Molecular Sciencecular Sciencecular Sciencecular Science

January 23, 2004 Osaka, Japan

Joel S. Miller Joel S. Miller Joel S. Miller Joel S. Miller Department of Chemistry Department of Chemistry Department of Chemistry Department of Chemistry

University of Utah University of Utah University of Utah University of Utah Salt Lake City, UT 84112-0850Salt Lake City, UT 84112-0850Salt Lake City, UT 84112-0850Salt Lake City, UT 84112-0850

JsmillerJsmillerJsmillerJsmiller@chem.@chem.@chem.@chem.utahutahutahutah....eduedueduedu

Magnetic Materials Crucial to theDevelopment of Science and Technology��Fe3O4 (Lodestone/Magnetite) Discovered (Unrecorded History)

1st Example of Technology TransferCrucial for Exploration of the New WorldS N

��Compass (Floating) Attributed to Chinese ~2500 ± 500 Years Ago

��

��

�Niels Bohr - Basis of Magnetism (Quantum Mechanics) - 1913

� Petrus Peregrinus de Maricourt 1st Experimentalist (Prove/Disprove Theory) - 1269 ◆ Improved Compass - Identified N /S Magnetic Poles ◆ Opposite Poles Attracted - Cannot 'Break' a Magnet ◆ Wrote Epistola de Magnete - 1269

��William Gilbert (Galileo's the 1st Experimentalist)◆ Created New Magnets (Fe) - Identified Earth as a Magnet◆ Wrote Treatise - De Magnete - 1600

��Low-cost Electricity - 1886ac Generating Station (Westinghouse, Buffalo, NY)

Applications Range from 1 µµµµW - 1 GW (Wristwatches - Motors - Switches)Motors and Telecommunications Acoustic MagnetomechanicalGenerators Information Technology Devices Applications

Measuring & Control Devicesdc Motors Switches Loudspeakers Holdings (Cow)Cranking Motors Sensors Headphones CouplingsStepper Motors Automation Devices Microphones BearingsRobotics Electro-mechanical Transducers Pick-ups Magnetic SeparationActuators Data Storage (Disk, Tape) Hearing Aids Magnetic Confinement

Focus Color (TV) Hearing Implants Microwaves Blood Analyzing

Superconductors MRI)

Diversity Illustrated by theUse of Magnets in Automobiles

Magnetic Materials Still Crucial toour High Tech Society

Western World Annual Production of Magnetic Materials 280 Mlb/yr (~10% Increase/yr) or $30 x 109 /yr (Global, 1999)

> 100 g / Person-on-Earth / Year

Molecular Materials Are Dia- or Paramagnetic

emumol10-6 10-5 10-4 10-3 10-2 10-1 1

• • • • • •• • • • • •• • • • • •

Diamagnetic

••Cuo

•H2O •TCNQ

TCNE

DDQ

••

FeCp* 2

Paramagnetic

•

•Coo

HgCo(SCN)4

•S=1/2 1.4 K

S=1/2 300 K

S=7/2 300 K

S=7/2 1.4 K

χχχχ < 0

χχχχ > 0

χχχχ > 0

χχχχ < 0

χχχχ-1

T TT

χχχχ = CT

Ms

Applied Field, H

Curie Law

Slope ∝∝∝∝ S,g Slope ∝∝∝∝ S,g

Brillouin Function

M = χχχχH

χ = F/[mH(dH/dz)]χ = M/H

Pauli or Temperature Independent Paramagnetic (TIP)

••

•

(2-D)

Mag

netiz

atio

n, M

χχ χχT o

r [8 χχ χχ

T]1/

2

� Spins (• or ↑↑↑↑ ) Key to All Magnetic Behavior

Spin Coupling Required for Ferromagnetic Behavior

emumol10-6 10-5 10-4 10-3 10-2 10-1 1

• • • • • •• • • • • •• • • • • •

Diamagnetic

••Cuo

•H2O •TCNQ

TCNE

DDQ

••

FeCp* 2

Paramagnetic•Feo

CrO2• •Fe3O4•

•Coo

HgCo(SCN)4

••

S=1/2 1.4 K

••

S=1/2 300 K

S=7/2 300 K

S=7/2 1.4 K

χχχχ < 0

χχχχ > 0

Antiferromagnetic CouplingFerromagnetic Coupling

χχχχ > 0

χχχχ < 0

χχχχ-1

T TT

[TTF][Cu(S2C4F6)2]•

Mag

netiz

atio

n, M

θθθθ < 0

θθθθ > 0

χχχχ = CT - θθθθ

θθθθ > 0

θθθθ < 0

Msχχ χχT

or [

8 χχ χχT

]1/2

Applied Field, H

SpontaneousMagnetization

at H = 0

θθθθ = 0

Saturation Magnetization, Ms, kemuOe/mol Feo 12.2 CrO2 8.8 Fe3O4 7.1 Molecule-based Magnets >16.3

Curie-Weiss Law

θθθθ = 0

θθθθ > 0

θθθθ < 0

θθθθ = 0

Metamagnetic

Antiferro

magnetic

Coupling

Ferromagnetic

Coupling

M(H) = f(history)

Ferromagnet����

� Spin Couping (J > 0) in 2- or 3-D Needed for a Magnet

� Magnetic Ordering / HYSTERESIS -Bulk Not Molecular Property [Technologically Very Important]

Ferromagnetism - Spin Alignment (Ordering) at TcBulk - Not Molecular Property

��������Ferromagnetic Coupling (θ > 0) Enhanced χ (χFO > χCurie) [Technologically Unimportant]

θθθθ < 0θθθθ = 0

χχχχParamagnet

Ferromagnetic Couplingθθθθ > 0

T

◆ Occurs When Spins Macroscopically CoupleχF >> χFO > χCurie

Domains [~12.5 x 107 Å3 = 6.6 x 105 Fe3O4 spins ] [~ 4.85 x 107 Å3 = 2.9 x 105 Fe spins ]

•

HH

H

H = M = 0 M > 0 M >> 0 M = Ms

M Ms

H HcrCoercive Field

RemanentField Mr

Hysteresis

•

•

•

•

•

•

��������Ferromagnetism ◆ Phase Transition to Ordered State (at Tc)

Tc

Ferromagnet Ordering•

Magnets Are Metal-basedd- or f- Valence Electrons

Organic-based Magnets? p-Valence Electrons?

Advantages & Disadvantages ofMolecule-Based Magnets

���� Advantages

Modulation of Properties

Improved Processing/Fabrication

Insulating

Transparent

Biocompatibility

High Permeability

���� Disadvantages

Unknown Materials

Low Density

High Equivalent Weight

Low Spin-Orbit Coupling &

Lande g-Values

�� Can Organic/Polymeric Magnets Be Made?

Not Energy Intensive

Unpaired Electron Spins Key toOrganic Magnetic Materials

Magnetism Due to Unpaired e- Spins (↑ / •)Number, NatureNumber, Nature && ProximityProximity ofof SpinsSpins

�� MagneticMagnetic BehaviorBehavior

Spin (S = Ms = Σms) + Orbital (L = Ml = Σml) Angular Momenta

� Inorganic Classical Magnets d- or f-orbital Metal Spin SitesMetallurgically Prepared

◆ Passive Organic Component - Only d- or f-orbital Metal Spin Sites

Orient Spins Control Magnetic Behavior &Do Not Contribute to Magnetic Behavior

� Organic (Non-classical) Magnets Prepared via Organic Chemistry Methodologies

◆ Active Organic Component - p-orbital Spin SitesContribute to Magnetic Behavior &Orient Spins Controlling Magnetic Behavior

[Fe(C5Me5)2][TCNE] Forms 1-D Chains

TCNEEo = 0.29 V (MeCN/SCE)

EA = 2.77 eV

FeII(C5Me5)2Eo = -0.12 V (vs SCE)

IP = 5.88 eVN

C

[FeIII(C5Me5)2]•+

[TCNE]•-

FeII(C5Me5)2 + TCNE →→→→ [FeIII(C5Me5)2]•+[TCNE]•- S = 0 S = 0 S = 1/2 S = 1/2

J. S. Miller, J. C. Calabrese, A. J. Epstein, R. W. Bigelow, J. H. Zhang,W. M. Reiff, J. Chem. Soc., Chem. Commun. 1986, 1026

Both Donor and [TCNE]•- Acceptor SpinsNeeded for Ferromagnetic Coupling (θθθθ > 0)

0

2

4

6

8

10

12

14

Mom

ent,

µef

f, µ B

0 50 100 150 200 250 300Temperature, T, K

[FeCp*2][TCNE]S = 1/2 S = 1/2

[FeCp*2][TCNQ]

S = 1/2 S = 1/2

[CoCp* 2][TCNE] S = 0 S = 1/2

[FeCp*2][C3(CN)5] S = 1/2 S = 0

D+

A-

D+

A-

D+

A-

•••

•••

0

100

200

300

400

500

600

700

800

Rec

ipro

cal M

olar

Sus

cept

ibili

ty, 1

/χχ χχ,

mol

/em

u

0 50 100 150 200 250 300

Temperature, T, K

[FeCp*2][TCNE] θθθθ = 30 K

[FeCp*2][TCNQ] θθθθ = 3 K

[FeCp*2][C3(CN)5] θθθθ = -1.2 K

[CoCp* 2][TCNE] θθθθ = -1.0 K

[Fe(C5Me5)2][TCNE]: Bulk Ferromagnet with aLarge Coercive Field and Large Saturation

and Large Remanent Magnetizations

Applied Field, H, Oe0 1000-1000

0

-10000

10000

5000

-5000

15000

-15000

Tc = 4.8 K

Mag

netiz

atio

n, M

, em

uOe/

mol

���� Able Store Information

���� 37% More Magnetic than Fe (/Fe or /mol)

Coercive Field Hcr, OeFe (Pure) 1Fe3O4 125γγγγ-Fe2O3 ~300γγγγ-Fe2O3:Co (2-3%) ~650CrO2 ~575Supermalloy 0.002Alnico 600[Fe(C5Me5)2][TCNE] 1,000 (2 K)

HcrSaturation Magnetization Ms, emuOe/molFe 12,200CrO2 8,800Co 9,500Fe3O4 7,100[Fe(C5Me5)2][TCNE], obs 16,300[Fe(C5Me5)2][TCNE], calc* 16,700

* Ms = [gFe + gTCNE]NSµB = [4 + 2]5585/2

Ms

[Fe(C5Me5)2][TCNE] Attracted toa Magnet at 4.2 K

[V(C6H6)2]+[TCNE]- Magnet Targeted�� [FeIII(C5Me5)2]+[TCNE]- Has a 4.8 K Tc

�� [MnIII(C5Me5)2]+[TCNE]- Has a 8.8 K Tc

� MnII(C5Me5)2 and Vo(C6H6)2

Have Different Electronic Structures MnII(C5Me5)2 S = 1/2 Vo(C6H6)2

E2g2

a

e2g

1g

e 1g

21gA

a1g

e2g

1ge

S = 1 [MnIII(C5Me5)2]+ or [VI(C6H6)2]+

2ge

1ga

E2g3

1ge

� [VI(C6H6)2]+[TCNE]- Should Be Ferromagnetic

Black Amorphous PyrophoricMaterial Isolated

� Vo(C6H6)2• + TCNE → Black PrecipitateLoss of Aromatic υCH Absorptions � Benzene Lost

Vo(C6H6)2 Black Precipitate

� Broad IR Absorptions in the υC≡≡≡≡N Region

Reduced TCNE σ-N (not π) Bound to V Science 1991, 252, 1415

Isolated [TCNE]•-

V[TCNE]x•yCH2Cl2 is a RoomTemperature Magnet

� V[TCNE]x•yCH2Cl2 Magnet Attracted to Teflon-coated Magnet at Room Temperature

��Easy to Separate

V[TCNE]x•yCH2Cl2 Magnet FitsWeak Random Anisotropy Model

� Spins in a Ferrimagnet with Weak Random Anisotropy:

� Modeled by:

Exchange Random Constant Zeeman Anisotropy Anisotropy Chudnovski et al. Phys. Rev. B 1986, 33, 251

Weak Random Anisotropy for Dr << J

� Magnetization Reduced from Saturation Magnetization Fits Model

WanderingAxis

Ferrimagnet

CorrelatedSpin Glass

H= −2J Si

i,j� • S j − Dr ni • Si[ ]

i�

2 − Dc Ni • Si[ ]i�

2 − gµB H • Si[ ]i�

3-D Network Structure Proposedfor V[TCNE]x•yS Magnet

VII{[TCNE]-}x{[TCNE]2-}1-x/2 or V1-yIIVy

III{[TCNE]-}x-y{[TCNE]2-}1-x/2+yx < 2

� Each TCNE Can Bind Up To 4 V'sMay Bind to 1,2, 3, or 4 V's Average ~ 3

N

N N

N V

V

V V

-•

VN

NN

NV

V

V

--

•-N

N N

N

V

V V

V

� Each V Can Bind Up To 6 Donor Atoms N from TCNE or Solvent (e. g., Cl from CH2Cl2)

� Amorphous 3-D Network Structure Built-upNonhomogeneous

CVD-Prepared Thin Films of V[TCNE]xMagnet Exhibit Enhanced Air Stability

<40o C CVDon Glass, Mica, NaCl, CsI, Si •••

�5 µm Film Attracted to Co5Sm MagnetRoom Temperature in Air

VacuumTCNE

Valve Valve

V[TCNE]x Film

ArV(CO)6

Ar

PressureGaugeHeater

on Glasson Teflon Tape

Co5Sm

V[TCNE]x Contains VII

[VII(NCMe)6][Barf]2

VII(TCNE)x film on Mica

VII(TCNE)x filmon Mica; 1 h Air

VII

VIIVv

Vv

Vv

Vv

VII

VII

MI2•xMeCN + TCNE + CH2Cl2 → MII(TCNE)2•xCH2Cl2

M υCN Tc, K J/kB, K

V 2189 2153 ~400 53Mn 2280 2224 2181 2171 107 6.1Fe 2279 2221 2177 2174 121 10Co 2284 2230 2187 2167 44 5.9Ni 2290 2237 2194 44 11

MII(TCNE)2•xCH2Cl2(M = Mn, Fe, Co, Ni)Molecule-based Magnets Made

J from Mean Field Theory

0

10

20

30

40

50

60

0 50 100 150 200 250 300

Mag

netiz

aton

, M, e

muO

e/m

ol

Temperature, T, K

Tc = 121 K

M = Fe

MI2.xMeCN + 2TCNE → MII[C4(CN)8](MeCN)2 (M = Mn,Fe)

[C4(CN)8]2- = µ4-σ-[TCNE]22- Dimer (S = 0)

µ4-[C4(CN)8]2- Isolated

Layered (2-D) StructureIndependent Spin (Paramagnetic) Behavior

υCN (M = Mn): 2304m, 2275m, 2212s, 2205s, 2153s, 2096sh m cm-1 υCN (M = Fe): 2307m, 2280m, 2213s, 2154s, 2108w cm-1

-- C

CC

C

CC

CC

C

C

C

C

NN

N N

N

N

N

N

M

M

M

M

1.6271.59

N C

M = Mn, Fe

1.6151.508

2.2182.221

[C4(CN)8]2- Is an Intermediate forM(TCNE)2 Magnets

MI2.xMeCN + TCNE � MII[C4(CN)8](NCMe)2 � MII(TCNE)2 Magnetµ4-[C4(CN)8]2-

= µ4 σ-[TCNE]22- Dimer (S = 0)Layered with Easily Lost Axial MeCNs [� Coordination Unsaturation] Weak Central C-C Bond (1.60 Å) Easily Broken [� Radical Formation]

Bond Breaking •• Radica

lsForm

ed••Bond Breaking

Solvent Loss(Vacant Sites)

••Bond Breaking

Solvent Loss(Vacant Sites)

BondingHeat

Photomodulated Magnetism Observedfor Mn(TCNE)2

� Magnetization Enhanced (25%) with 488 nm (2.52 eV) Light

Persists for Several Days (<50 K)

� Partially Reversed with 514 nm (2.41 eV) Light

[MnTPP][TCNE]•2PhMe ExhibitsUnusual Magnetic Properties

N Mn

N

N

NC

N

CN

CN

NC

+ ���� [MnIIITPP]+[TCNE]•-

4.66 µB 293 KLarge 6.68 µB 78 K

Predicted 5.20 µB ObservedTCNE

MnIITPP

meso-Tetraphenylporphinatomanganese(II) + TCNE ���� [MnIIITPP][TCNE]•x(solvent) MnIITPP

Summerville, D. A.; Cape, T. W.; Johnson, E. D.; Basolo, F. Inorg. Chem. 1978, 17, 3297

trans-µ-[TCNE]•- Present in[MnTPP]+[TCNE]•-•2PhMe

��Forms Parallel 1-D Chains

1.37 (1) Å sp2-C-sp2-C Distance Consistent with [TCNE]•- 1.34 TCNE1.39 [TCNE]•-1.49 [TCNE]2-

[MnTPP][TCNE]•2PhMe is a Magnet

0

50

100

150

200

Mag

netiz

atio

n, M

, em

uOe/

mol

0 10 20 30 40 50 60Temperature, T, K

[MnTPP][TCNE]•2PhMe

3 Oe

Tc ~ 16 K

Tc = 16 K Hysteresis Observed CoerciveField (Hcr) = 375 Oe at 5 K

-15000

-10000

-5000

0

5000

10000

15000

-4000 -2000 0 2000 4000Applied Magnetic Field, H, Oe

[MnTPP][TCNE]•2PhMe

5 K

Hcr = 375 Oe

[MnTClPP][TCNE]•2S Prepared [MnTClPP][TCNE]•2PhMe [MnTClPP][TCNE]•2CH2Cl2

2201m, 2160s υCN, cm-1 2195m, 2138s175 oC ∆ ↓ - PhMe ∆ ↓ - CH2Cl2

2201m, 2159s [ α-phase ] 2195m, 2137s [ γ-phase ] or in n-Octane [reflux]

2190m, 2132s [ β-phase ]

���� 5 Forms of [MnTClPP][TCNE]

All 5 Pseudeopolymorphs Magnetically Order(6.7 < Tc < 14.1 K)

All Form 1-D Chain Structures withDiffering Orientations

IntrachainMn...Mn

Mn-N

Mn-Mn-N

Mn-N-C

MnPorphryinPlane

TCNEPlane

MnPorphryin - TCNEDihedral Angle

p-H PhMe 2.306 10.116 147.6 55.4 19.3 9.28p-H xylene 2.288 10.218 167.0 82.3 14.8 9.93p-H C6H4Cl2 2.356 9.489 125.1 29.9 31.2 7.82p-H C6H3Cl3 2.334 9.588 130.2 36.8 29.0 8.10p-Cl CH 2Cl2 2.276 9.894 143.1 52.4 22.7 8.94p-Cl PhMe 2.267 10.189 167.2 86.8 14.6 9.85o-Cl PhMe 2.361 10.387 150.7 57.8 16.0 9.79o-F PhMe 2.313 10.185 148.6 55.4 18.3 9.40m-F PhMe 2.323 10.375 169.3 82.7 12.6 10.14p-But xylene 2.254 10.189 169.5 89.3 13.8 9.953,5- But PhMe 2.366 8.678 111.5 21.6 39.9 6.943,5 -But,4- OH PhMe 2.299 8.587 129.0 33.6 29.4 7.43p-CF3 C6H5Cl 2.300 10.387 162.9 75.4 15.6 9.80

Ave (30 cpds) 2.312 9.855 152.0 54.4 22.7 8.92∆ 0.130 1.800 44.4 67.8 27.3 3.20% 5.6 18.3 29.2 125.0 120.0 35.8

Mn-NC, Mn...Mn, Mn-N-C, Dihedral Mn-Mn-N, ⊥ ⊥ ⊥ ⊥ MnN4- Å Å deg Angle, deg deg MnN4, Å

Antiferromagnetic CouplingProportional to θθθθ'

Antiferromagnetically Coupled 1-D, J1d, Chains ����

∝∝∝∝ Effective θ, θ' ⇐⇐⇐⇐ Curie-Weiss Model Fit

θ’ Model Dependent (Observed)> θ' ���� > Long Range Ferromagnetic Coupling

0

0

100

200

300Temperature, T, Kθ' > 0

Tmin => Antiferromagnetic Coupling

θ < 0Antiferromagnetic

CouplingFerromagnetic

Coupling(long range)

1/χχ χχ

[MnTClPP][TCNE]•2PhMe

167.20

Smaller Angles Correlate withEnhanced Antiferromagnetic Coupling

θθθθ' = 17 K[MnTOMePP][TCNE]•2PhMe

165.50

MnNC Angle

θθθθ' = 21 K[MnTFPP][TCNE]•2PhMe

150.30

*

θθθθ' = 45 K

[MnTPP][TCNE]•2PhMe

146.80

θθθθ' = 61 K[MnTP*P][TCNE]•2PhMe

128.90

θθθθ' = 90 K* Major Orientation

0

20

40

60

80

100

θθ θθ' , K

120 130 140 150 160 170 180Mn-N-C, Angle, δδδδ', deg

Smaller Angles Correlate with Enhancedσσσσ-dz2-pz Overlap

Due to Admixture of Pyrrol N pz Orbitals

0.000

0.005

0.010

0.015

O v

0

20

40

60

80

100

θθ θθ', K

120 130 140 150 160 170 180

dz2

dxz

dyzdxy

θθθθ'

Mn-N-C Angle, δδδδ', deg

dπ-π∗ π OverlapNporNpor MnIII

z

C

N [TCNE].- π*δ' = 180o

δ = 90o

δ' < 180o

MnIII

dz2

δ < 90o

dz2-pz σ Overlap Dominates

C

N

Numerous Strong e- Acceptors StabilizeMagnetic Ordering

[Mn(Porphyrin)][TCNE] Form a Family of Ferrimagnets [TCNE]- is Not Unique

Other Strong e- Acceptors Form 1-D Ferrimagnets

Me2TCNQ TCNQF4 Me2DCNQI TCPQ

NN

Me

Me

N

N

F F

FF N

NN

N

Me

Me N

NN

NN

N

N

N

Tc = 6.0 K 7.3 K 6.0 K 12.3 K

OO

Cl Cl

ClCl

Chloranil

Zigzag Chains with [Me2TCNQ]-Ken-ichi Sugiura, Institute of Scientific and Industrial Research, Osaka University

Chloranil

Tc = 13 K

Linear Chains with [Chloranil]•-

Ru Acetate Dimers Identified as Building Block for Magnets

Several M2(OAc)4 Have Dimeric D4h Structures

M

O

C

M MM Bond S Scation (Bond Order) Cr Quadruple (4) 0Cu None (0 0, 1Mo Quadruple (4, 3.5, 3) 0 1/2Ru Double (2, 2.5) 1 3/2Rh Single (1, 3/2) 0 1/2

σ

σ∗

π

π*

δ

δ*

E

����S = 1 & 3/2 � [Ru2(OAc)4]n (n = 0, 1+) � Molecule-based Magnet Building Block

� π*2δ*1

Sought Anions with Larger SSelected - S = 3/2 [CrIII(CN)6]3-

Each [RuII/III2(O2CR)4]+ Can Bridge 2 [CrIII(CN)6]3-'s

Each [CrIII(CN)6]3- Can Coordinate 6 [RuII/III2(O2CR)4]+'s

Charge Balance Requires 3 S = 3/2 [RuII/III2(O2CR)4]+ per S = 3/2 [CrIII(CN)6]3-

Each [RuII/III2(O2CR)4]+ Bridges 2 [CrIII(CN)6]3- &

Each [CrIII(CN)6]3- Bridges 6 [RuII/III2(O2CR)4]+

C

Cr

C

CCC

N Ru Ru N C Cr CN

C

CC

CC

N

N

NN

N

NN

O O

O O

Me

Me

O O

Me

O O

Me

N

N

���� 3-D Cubic Network Structure Can Form Due to 1-D [RuII/III

2(O2CR)4]+ Bonding to 3-D [CrIII(CN)6]3- in 3-D Charge is Compensated

[Ru2(O2CMe)4]3[CrIII(CN)6] Prepared

[CrIII(CN)6]3- + 3 [RuII/III2(O2CMe)4]+ → [RuII/III

2(O2CMe)4]3[CrIII(CN)6]

M υ(C≡N), cm-1 %Ccalc %Cobs %Hcalc %Hobs %Ncalc %Nobs a, ÅCr 2138 23.66 23.82 2.38 2.48 5.52 5.72 13.34

������������[RuII/III2(O2CMe)4]3[MIII(CN)6] Powder Diffraction Indexed toBody Centered Cubic (bcc) Lattice

a ~ 13.34 Å ~ 2 Cr-C + 2 C≡N + 2 N-Ru + Ru=Ru Bond Distances

���� Propose 3-D Network Structure with each Unit Cell Axis

•••Cr-C≡N-Ru=Ru-N≡C-Cr••• Linkages Along Each Axis

Primitive (P) not Body Centered (B) Lattice !

2222θθθθ0

100

200

300

400

10 20 30 40 50

Cou

nts

110

200

211220

310222

321

321 * 330510431 530

433

600442611532521

440**

[RuII/III2(O2CMe)4]3[CrIII(CN)6]

Propose Cubic 3-D Network Structurefor [RuII/III

2(O2CMe)4]3[CrIII(CN)6]Cubic with •••Cr-C≡N-Ru=Ru-N≡C-Cr••• Linkages Along Each Axis [RuII/III

2(O2CMe)4]+ Rotated 45o Minimizing Steric Interactions Primitive (P) Lattice(50% Void Space for Solvent)

ρcalc = 1.07 g/cm3

–

ρcalc = 2.13 g/cm3

ρobs = 2.08 g/cm3

Body Centered (B) Lattice����2nd Interpenetrating Lattice����(No Void Space for Solvent)

Rietveld Anaylsis a = 13.37553 Å Im3mJae-Hyuk Her,Peter W. Stephens

[Ru2(O2CMe)4]3[Cr(CN)6] Magnetically Orders (Tc = 33 K)

-20

-10

0

10

20

30

-0.05

0

0.05

0.1

0.15

15 20 25 30 35 40 45

χχ χχ ', e

mu

mol

-1

χχ χχ'", emu m

ol -1

Temperature, T, K

χχχχ'

χχχχ"

10 Hz100 Hz1000 Hz

��������Tc = 33 ± 1 K��������No Frequency Dependence��������Metamagnetic-like Behavior ( Hc ~ 1500 Oe )��������Hysteresis - Very Unusual Constricted Shape

0

5

10

15

20

25

30

35

0 20 40 60 80 100

[Ru2(OAc)4]3[Cr(CN)6]

µµ µµ eff, µµ µµ

B

Temperature, T, K

• ZFC• FC

-20000

-15000

-10000

-5000

0

5000

10000

15000

20000

-6000 -4000 -2000 0 2000 4000 6000

Mag

netiz

atio

n, M

, em

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Applied Field, H, Oe

Organic-based Magnets Achieved

“ Riches upon riches: reports of newdiscoveries, marvelous molecules,unmakeable, unthinkable yesterday -made today, reproducible with ease. ..incredible properties of novel high-temperature superconductors, organicferromagnets, and supercritical solvents.”

Roald Hoffmann, Angew. Chem. internat. Edit. 1988, 27, 1593

Scott, A. J. Chem. Soc, 1916, 338

Many Opportunities for Organic Magnets���� Supramolecular Magnets Prepared

Tc up to 400 K Tc Controllable

High Saturation Magnetizations Large Coercive Fields

Feasibly Demonstrated for Magnetic Shielding

���� Many Supramolecular Magnets IdentifiedPrepared at Room Temperature (Non-metallurgical)

���� Abundant Opportunities for Chemists ◆ Synthesis

Organic / Organometallic / Polymer◆ Modeling / Computational

Electronic Structure - Molecular Orbital Magnetic Susceptibility / Magnetization

◆ Experimental WorkSpecific Heat, AC Susceptibility, Optical Studies, Ferromagnetic Resonance, Pressure Dependencies etc...

◆ Theory New Theories, Twists, Phenomena etc•••

Magnets Have Come Long Way

and Have a Bright Futureand Have a Bright Future

S N

Magnetic Materials Soughtin the Next Millennium

Transparent, Insulating Magnets 

Flexible Magnets 

Photomagnets 

Ultra 'Hard' Magnets (Very High Coercivity) 

High Permeability (Very 'Soft') Magnets(Very Large Response to Small Applied Magnetic Fields)

 

Liquid Magnets 

Spintronic/Spin Transistor Materials

QuickTime™ and a YUV420 codec decompressor are needed to see this p

Drop in and Visit the University ofUtah Department of Chemistry

Chemistry

Chemistry is at Olympics Ground Zero

✸

Opening & Closing Ceremonies

Olympic Caldron

Molecule-based Magnet ExplorersØyvind Hatlevik (G) Konstantin Pokhodnya (VP) Stephen Etzkorn (G) Wendy Hibbs (G) Arno Böhm (PD, BASF) Carmen Kmety (G) Shireen Marshall (G) Kai-Ming Chi (PD, Chung-Chen U) Dusan Pejakovic (G) Rico del Sesto (G) Dan Glatzhofer (PD, U OK) Nandyala Raju (PD) Jim Raebiger (PD) Xiaotai Wang (PD,U CO Denver) Eric Anderson (G, Kan S U) Erik Brandon (G, JPL) Gordon Yee (PD, U CO) Gang Du (G, Lakeshore) Doug Gordon (G, deceased) Yuanlin Zhou (PD, Inflazyme) Keith Cromack (G, Abbott) Wayne Buschmann (G, PD, LANL) Will Brinckerhoff (G, APL Johns Hopkins) Mitch Johnson (G,LANL) Anamish Chackraborty (G, Carnegie Mellon) Jamie Manson (G, PD, ANL) Satish Chittipeddi (G, Lucent) Durrell Rittenberg (G, PD, U Wash) Mihai Gîrtu (G, U Constanta) Laura Deakin (PD,U Alberta) Olivier Heres (G, Sorbonne) Jinkwon Kim (PD, Kongju U) Jinsoo Joo (G, Korea U) Scott Paulson (PD, U Calgary) Steve Long (G, Consulting) Leigh Porter (PD, deceased) Brian Moran (G, Milliken) Jie Zhang (PD, Samsung) Sureswaran Narayan (G, Nehru Res Ctr) Lutz Baars-Hibbe (U, Braunshweig) Patricia Vaca (PD, CNRS, FR) Sandy Kalm (U, NYU Medical School) Vasco de Gama (PD, Inst. Nucl. Tech, PT) Ben Kalm (U, OSU Medical School) Rene Laversanne (PD, CNRS, FR) Nate Petersen (U) Chuck Wynn (PD, XonTech) Michele Yates (U, Graduate School) Ping Zhou (PD, Rosenthal Securities) Atta Arif (Crystallograpy) Mike Selover (U, Fermi Lab) Henry White (Eletrochemistry) Chris Hahm (U, OSU Grad School)

Current Group Member italics Arthur Epstein (Magnetic Studies)

Supported in part by DOE (DMS, AEP), NSF (CHE, DMR, INT), ACS-PRF, AFOSR< DARPA/ONR, UofU

Molecule-based Magnet Explorers

DuPont Joe Calabrese, Dave Dixon, Dick Flippen, Dave Groski, Dick Harlow, Nancy Jones, Paul Krusic, Juan Manriquez,Scott McLean, Dermot O'Hare, Andy Suna, Carlos Vazquez, Mike Ward, Ed Wasserman

Osaka University Ken-ichi Sugiura, Yoshiteru Sakata (Syntheses)Johannes-Gutenberg Universität Jürgen Ensling, Vadim Ksenofontov, Philipp Gütlich (Mössbauer, Magnetic Studies)Northeastern University Jian Zhang, Bill Reiff (Mössbauer)NIST Qing Huang, Ross Erwin, Jeff Lynn (Neutron Diffraction); George Candela, Lloyd Swartzendruber (Magnetic Studies)Brookhaven National Laboratory Goetz Bendele, Silvina Pagola, Peter Stephens (Synchrotron X-ray Diffraction)

Steve Shapiro, Andrei Zheludev (Neutron Diffraction)Centre d'Etudes Nucléaires (Grenoble, France) Eric Ressouche, Jacques Schweizer (Neutron Diffraction)University of Delaware Ilia Guzei, Chris Incarvito, Do Lee, Louise Liable-Sands, Glenn Yap, Arnie Rheingold (Structural Studies)University of Alabama Robin Rogers (Structural Studies)BrandiesUniversity William Desmarais, Michael Vela, Jim Fox, Donna Guerrer, Art Reis, Jr., Bruce Foxman (Structural Studies)Bruker Instruments Chuck Campana (Structural Studies)Hauptman-Woodward Medical Research Institute Brian Burkhart (Structural Studies)National High Magnetic Field Laboratory Scott McCall, Jack Crow (Specific Heat)Quantum Design Randy Black, Jost Diederichs (Specific Heat)Technische Universität München Christian Kollmar (Computational Studies)National Reseach Council (Canada) John Morton, Keith Preston (EPR)University of Houston Z. J. Huang, F. Cheng, Y. T. Ren, Y. Y. Xue, Paul Chu (Magnetic Studies under Pressure Studies)University of Miami S. Zane, Fulin Zuo (Magnetic Studies)Columbia University L. P. Le, A. Keren, G. M. Luke, W. D. Wu, Tomo Uemura (Magnetic Studies)Ceram Physics William Lawless (Specific Heat)

Supported in part by theDOE (DMS, AEP), NSF (CHE, DMR, INT), ACS-PRF, AFOSR, DARPA/ONR, UofU