crystal structure and magnetic property of cobalt glutarate, co[o 2 c(ch 2 ) 3 co 2 ]
DESCRIPTION
Crystal Structure and Magnetic Property of Cobalt Glutarate, Co[O 2 C(CH 2 ) 3 CO 2 ]. 이 윤 원 , 김 유 진 , 정 덕 영 * Department of Chemistry - BK21, SungKyunKwan University. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
Crystal Structure and Crystal Structure and Magnetic Property of Magnetic Property of
Cobalt Glutarate, Cobalt Glutarate, Co[OCo[O22C(CHC(CH22))33COCO22]]
이 윤 원 , 김 유 진 , 정 덕 영 **
Department of Chemistry - BK21,Department of Chemistry - BK21,SungKyunKwan University SungKyunKwan University
Introduction
A reasonable approach to build three-dimensional structures based on layered structural motifs is to control the packing of layers by organic pillars of changeable length and type. Pillared structures are potentially important for applications in catalysis, magneto material and etc. A variety of layered structure with transition metal and dicarboxylate have been synthesized.
Single crystal of Co-glutarate, Co[O2C(CH2)3CO2], was synthesized as single crystal under hydrothermal condition, characterized by XRD, IR, TG, UV-vis, and SQUID. It is interesting to note that this structure represents the first example of carboxylate pillared structures containing only tetrahedral sites of cobalt(II) with two different conformation of glutarate ligands(anti/gauche-form).
Experimental Procedure
aqueousKOH 1.5 M 5 mL
Metal ion source; CoCl2·6H2O 5 mmol
Ligand;Glutaric acid 5 mmol
HO
O O
OH
oven
180ºC
Heat in oven at 180 °C for 24 h under
hydrothermal condition
Quench in cold water
Dark purple crystals(Filter, wash with alcohol, yields in ~70%) Co-glutarate,
Co[O2C(CH2)3CO2]
TeflonVessel
~pH 4.5
Crystal Structure Data
Empirical formula CoC5H6O4
Formula weight 189.03 Crystal system monoclinicSpace group P2/cUnit cell dimensions a = 14.002(3) Å
b = 4.8064(10) Å c= 9.274(3) Åα= 90ºβ= 90.50(2)ºγ= 90º
Volume, Z 624.1(3) Å3, 4 Density (calculated) 2.012 mg/m3
Final R indices R1 = 0.0480
wR2 = 0.1316
R indices (all data) R1 = 0.0566
wR2 = 0.1601
Co
O1
O4
O3
O2
C4
C5
C6
C1
C2
C3
Asymmetric Unit
Gauche-form
Anti-form
Two Different Conformations of Glutarate Ligands
115.6º115.6º
115.6º
115.2º 115.2º109.8º
Inorganic Layer
b
c
c
a
b
a
c
4.81 Å
4.63 Å
7.01 Å
90.5°
6.99 Å
= Gauche-form
= Anti-form
(syn-anti / syn-anti mode)
syn syn
anti anti
(syn-anti / syn-anti mode)
syn
synanti
anti
Gauche-form
Anti-form
Bridging mode ofCarboxylate
c
a90.5°
Crystal Structure View
c
(100)(100)
90°
b
a
(001)(001)
90°Gauche-form Anti-formAnti-form
b
Decomposition of Organic Chains
Rate = 10 °C/minUnder N2-gas Blowing
39%
Co[O2C(CH2)3CO2] CoO (39.6%) (~ 450 oC)
No hydrate water
C-O stretching
C-C stretch
No C=O stretch
IR and TG
4000 3500 3000 2500 2000 1500 1000 500
769.6531
1405.244
1534.484
2957
Tra
nsm
ittan
ce(%
)
Wavenumbers(cm -1)
IR TG
UV-Vis Spectrum
500 1000 15000.0
0.1
0.2
2300
2100
1568
1274
826
558
258
Ab
so
rba
nce
Wavelength(nm)
Color : Dark purple
Peak Assignment1274 nm (7849 cm-1): 4A2g(F) 4T1g(F)558 nm (179211cm-1): 4A2g(F) 4T1g(P)
Crystal Field Strength:t = 4418 cm-1
Racah parameter: Bt = 788 cm-1
106.5
99.0 103.3
110.3
116.4
121.4
Co2+(d7) in Td
Strong fieldground configuration
: e4t23
Strong fieldground term
: 4A2
Magnetization
0 50 100 150 200 250 3000
20
40
60
80
100
120
140
160
180
200
y = 0.57 x + 5.61
1/
M
Temperature(K)
1/M
Linear Fit
C = 0.18 cm3K/mol = -1.01 K eff = 3.69 B (at 300 K)
*eff (expt): 4.30-5.20 B for H.S.
1.73 B for L.S. state of Co2+
1/ = T/C - /C (at T > 50 K)= 0.57 T + 5.61
(100G, MPMS-SQUID magnetometer)
0 50 100 150 200 250 3000.00
0.01
0.02
0.03
0.04
0.05
M T
M(e
mu
/Co
)
Temperature(K)
0
1
2
Co2+(in Td) ; 3d7
Conclusion
All cobalt atoms were coordinated to four oxygen atoms (Td symmetry) by carboxylate groups to form an organic/inorganic hybrid compound in three-dimension. Interestingly, two different conformations of alkyl chain in glutarate ligands (anti-form and gauche-form) were observed in the crystal structure of the prepared Co-gluatarate compounds. Magnetic measurement showed long range with eff= 3.69 B (at 300 K).
Acknowledgement We acknowledge financial support from the Electron Spin Science Center at POSTECH, which established as the excellent science research center by the KOSEF. The Korea Basic Science Institute provided us with SQUID magnetometer measurements for the present study.