UV/vis Spectroscopy = Electronic Spectroscopy What does it monitor / probe?

UV/vis Spectroscopy = Electronic Spectroscopy

What does it monitor / probe?

What information about molecule can one obtain?

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

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


Accurate mass : 556.014160 for MoOdetc3


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


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


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


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UV/vis Spectroscopy = Electronic Spectroscopy What does it monitor / probe?