third osaka city university international symposium...
TRANSCRIPT
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.@[email protected]
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•
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
[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
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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•••
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
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Drop in and Visit the University ofUtah Department of Chemistry
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