spectroscopic analysis of molybdenum model compounds by: 1.infrared 2. 1 h nmr 3.electronic (uv/vis)...
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Spectroscopic Analysis of Molybdenum Model Compounds
by:
1. Infrared
2. 1H NMR
3. Electronic (UV/vis)
4. ESI-MS
Why?
What did I make?
How do molecules differ?
UV/vis Spectroscopy = Electronic Spectroscopy
What does it monitor / probe?
What information about molecule can one obtain?
What if 350 nm has = 8,000 M-
1cm-1 and 550 nm has = 80 M-1cm-1 ?
IR Spectroscopy
What does it tell us?
What more information about molecule can one obtain?
Mo
O
Mo
O
Mo
O
Mo
O
O
NMo
OC CO
N
CO
NNN
N
BH
1H NMR: what do you expect to see?
NMo
OC CO
N
CO
NNN
N
BH
a
b
c
a
b
c
Expected: 3 resonances, 2 -CH3 (a & c with 6H) and 1 H (b)
( B-H not visible due to broadening)
… plus H’s on cation TEA = [N(CH2CH3)4]+
[Tp*Mo(S)(S4)]—
N
MoS
SN S
NN
N
N
HB
S
S
1H NMR: what do you expect to see?
N
MoS
XN S
NN
N
N
HB
S
S
a
a
a
e
e
b
b
b
d
d
Mo=S
Mo=O
TEA+
-CH2-
TEA+
-CH3
c
c
c
f
f
N
MoS
XN S
NN
N
N
HB
S
S
a
bc
de
f ab
c
a
b
c
de f
Mo=S
Mo=O
TEA+
-CH2-
TEA+
-CH3
NN
N N Mo4+
NHB
N
X
S
S
R2
X = S, O
R1
R1 ≠ R2: How many H’s expected in NMR from pyrazole rings?
All -methyl and ring H’s will be unique: see 6 -Me and 3 ring H
How many H’s expected in NMR from detc liagnds?
Mass Spectometry Facility
Dr. Arpad Somogyi
Electrospray Ionization Mass Spectrometry ESI-MS
black box
massdetector
magnetic fieldseparates light and heavymass ions
Molecules in gas phase as ions + or -
Electron impact ionization
Electrospray ionization method
makes tiny droplets Vacuum removes solvent Electric potential creates + and - ions
All Mo molecules are identified by a characteristic series of lines:Mo isotopes: 92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo,
YELLOW (calculated mass spectrum)
Mass Relative abundance474.000 6.12476.000 8.84477.000 7.34478.000 11.91479.000 10.57480.000 17.08482.000 14.14481.000 7.06484.000 6.00483.000 3.06486.000 1.29485.000 0.94488.000 0.14475.000 0.88487.000 0.18489.000 0.02490.000 0.01
RED (calculated mass spectrum)
Mass Relative abundance404.000 11.48406.000 8.72407.000 12.64408.000 15.04409.000 10.98410.000 20.73412.000 10.58411.000 4.24414.000 1.58405.000 1.66413.000 1.55415.000 0.21416.000 0.10417.000 0.01418.000 0.00
BLUE (calculated mass spectrum)
Mass Relative abundance468.000 10.36470.000 8.81471.000 11.67472.000 14.47473.000 11.15474.000 20.10476.000 11.30475.000 5.04478.000 2.33469.000 1.66477.000 1.93479.000 0.35480.000 0.24481.000 0.03482.000 0.01483.000 0.00
PURPLE (calculated mass spectrum)
Mass Relative abundance824.000 1.32826.000 2.03827.000 3.18828.000 4.63829.000 5.22830.000 9.33832.000 11.22831.000 7.37834.000 10.77833.000 9.98835.000 8.87836.000 9.11837.000 5.00838.000 5.46840.000 1.99839.000 1.99842.000 0.43841.000 0.58844.000 0.06
Y
B
P
R
All have one Mo atom
More lines, more Mo atoms
RED mass spectrum
409.6
YELLOW mass spectrum
444.6
BLUE full mass spectrum
YELLOW (high mass species)
Accurate mass : 540.019287 for Modetc3
Mass Relative abundance536.000 9.82538.000 8.43539.000 11.53540.000 14.33541.000 11.33542.000 19.63544.000 10.96537.000 2.13543.000 5.83545.000 2.42546.000 2.30547.000 0.45548.000 0.25549.000 0.04550.000 0.02551.000 0.00
Accurate mass : 556.014160 for MoOdetc3
Mass Relative abundance552.000 9.80554.000 8.44555.000 11.51556.000 14.32557.000 11.33558.000 19.62560.000 10.98559.000 5.85562.000 2.32553.000 2.12561.000 2.43563.000 0.46564.000 0.25565.000 0.04566.000 0.02567.000 0.00
MoOdetc2: Mo1S4O1N2C10H20 mass: 408.48 g/mol
MoOdetc2. NCCH3: Mo1S4O1N3C12H23 mass: 449.53 g/mol
MoOCl2detc2: MoCl2S4O1N2C10H20 mass: 479.38 g/mol
Mo2O3detc4: Mo2S8O3N4C20H40 mass: 832.96 g/mol
MoOS2detc2: MoS6ON2C10H20 mass: 472.61 g/mol
MoOCl2detc2: MoCl2S4O1N2C10H20
Accurate mass : 478.893738
Mass Relative abundance474.000 6.12476.000 8.84477.000 7.34478.000 11.91479.000 10.57480.000 17.08482.000 14.14481.000 7.06484.000 6.00483.000 3.06486.000 1.29485.000 0.94488.000 0.14475.000 0.88487.000 0.18489.000 0.02490.000 0.01
MoOdetc2: Mo1S4O1N2C10H20
Accurate mass : 407.987732
Mass Relative abundance404.000 11.48406.000 8.72407.000 12.64408.000 15.04409.000 10.98410.000 20.73412.000 10.58411.000 4.24414.000 1.58405.000 1.66413.000 1.55415.000 0.21416.000 0.10417.000 0.01418.000 0.00
Mo2O3detc4: Mo2S8O3N4C20H40
Accurate mass : 831.970276
Mass Relative abundance824.000 1.32826.000 2.03827.000 3.18828.000 4.63829.000 5.22830.000 9.33832.000 11.22831.000 7.37834.000 10.77833.000 9.98835.000 8.87836.000 9.11837.000 5.00838.000 5.46840.000 1.99839.000 1.99842.000 0.43841.000 0.58844.000 0.06
MoOS2detc2: MoS6ON2C10H20Accurate mass : 471.931763
Mass Relative abundance468.000 10.36470.000 8.81471.000 11.67472.000 14.47473.000 11.15474.000 20.10476.000 11.30475.000 5.04478.000 2.33469.000 1.66477.000 1.93479.000 0.35480.000 0.24481.000 0.03482.000 0.01483.000 0.00
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