Spectroscopic Analysis of Molybdenum Model Compounds

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• Spectroscopic Analysis of Molybdenum Model
  Compounds
• by
• Infrared
• 1H NMR
• Electronic (UV/vis)
• ESI-MS
• Why?
• What did I make?
• How do molecules differ?

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UV/vis Spectroscopy Electronic
Spectroscopy What does it monitor / probe? What
information about molecule can one obtain?
What if l 350 nm has e 8,000 M-1cm-1 and l 550
nm has e 80 M-1cm-1 ?
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IR Spectroscopy What does it tell us? What more
information about molecule can one obtain?
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1H NMR what do you expect to see?
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a
a
b
b
c
c
Expected 3 resonances, 2 -CH3 (a c with 6H)
and 1 H (b) ( B-H not visible due
to broadening) plus Hs on cation TEA
N(CH2CH3)4
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1H NMR what do you expect to see?
TpMo(S)(S4)
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MoS
MoO
TEA -CH3
TEA -CH2-
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d
e
MoS
MoO
f
a
b
c
a
TEA -CH3
b
c
TEA -CH2-
a
c
b
d
e
f
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R1 ? R2 How many Hs expected in NMR from
pyrazole rings?
All -methyl and ring Hs will be unique see 6
-Me and 3 ring H
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How many Hs expected in NMR from detc liagnds?
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Mass Spectometry Facility
Dr. Arpad Somogyi
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Electrospray Ionization Mass Spectrometry ESI-MS
black box
Molecules in gas phase as ions or -
magnetic field separates light and heavy mass
ions
mass detector
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Electron impact ionization
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Electrospray ionization method
Electric potential creates and - ions
makes tiny droplets
Vacuum removes solvent
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All Mo molecules are identified by a
characteristic series of lines Mo isotopes
92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo,
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YELLOW (calculated mass spectrum) Mass Relative
abundance 474.000 6.12 476.000 8.84 477.000
7.34 478.000 11.91 479.000 10.57 480.000
17.08 482.000 14.14 481.000 7.06 484.000
6.00 483.000 3.06 486.000 1.29 485.000
0.94 488.000 0.14 475.000 0.88 487.000
0.18 489.000 0.02 490.000 0.01
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RED (calculated mass spectrum) Mass Relative
abundance 404.000 11.48 406.000 8.72 407.000
12.64 408.000 15.04 409.000 10.98 410.000
20.73 412.000 10.58 411.000 4.24 414.000
1.58 405.000 1.66 413.000 1.55 415.000
0.21 416.000 0.10 417.000 0.01 418.000 0.00
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BLUE (calculated mass spectrum) Mass Relative
abundance 468.000 10.36 470.000 8.81 471.000
11.67 472.000 14.47 473.000 11.15 474.000
20.10 476.000 11.30 475.000 5.04 478.000
2.33 469.000 1.66 477.000 1.93 479.000
0.35 480.000 0.24 481.000 0.03 482.000
0.01 483.000 0.00
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PURPLE (calculated mass spectrum) Mass Relative
abundance 824.000 1.32 826.000 2.03 827.000
3.18 828.000 4.63 829.000 5.22 830.000
9.33 832.000 11.22 831.000 7.37 834.000
10.77 833.000 9.98 835.000 8.87 836.000
9.11 837.000 5.00 838.000 5.46 840.000
1.99 839.000 1.99 842.000 0.43 841.000
0.58 844.000 0.06
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Y
R
P
More lines, more Mo atoms
B
All have one Mo atom
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RED mass spectrum
409.6
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YELLOW mass spectrum
444.6
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BLUE full mass spectrum
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YELLOW (high mass species)
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Accurate mass 540.019287 for Modetc3 Mass Relat
ive abundance 536.000 9.82 538.000 8.43 539.000
11.53 540.000 14.33 541.000 11.33 542.000
19.63 544.000 10.96 537.000 2.13 543.000
5.83 545.000 2.42 546.000 2.30 547.000
0.45 548.000 0.25 549.000 0.04 550.000
0.02 551.000 0.00
Accurate mass 556.014160 for MoOdetc3 Mass Rel
ative abundance 552.000 9.80 554.000
8.44 555.000 11.51 556.000 14.32 557.000
11.33 558.000 19.62 560.000 10.98 559.000
5.85 562.000 2.32 553.000 2.12 561.000
2.43 563.000 0.46 564.000 0.25 565.000
0.04 566.000 0.02 567.000 0.00
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MoOdetc2 Mo1S4O1N2C10H20 mass 408.48
g/mol MoOdetc2. NCCH3 Mo1S4O1N3C12H23 mass
449.53 g/mol MoOCl2detc2 MoCl2S4O1N2C10H20 mas
s 479.38 g/mol Mo2O3detc4 Mo2S8O3N4C20H40 ma
ss 832.96 g/mol MoOS2detc2
MoS6ON2C10H20 mass 472.61 g/mol
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MoOCl2detc2 MoCl2S4O1N2C10H20 Accurate mass
478.893738 Mass Relative abundance 474.000
6.12 476.000 8.84 477.000 7.34 478.000
11.91 479.000 10.57 480.000 17.08 482.000
14.14 481.000 7.06 484.000 6.00 483.000
3.06 486.000 1.29 485.000 0.94 488.000
0.14 475.000 0.88 487.000 0.18 489.000
0.02 490.000 0.01
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MoOdetc2 Mo1S4O1N2C10H20 Accurate mass
407.987732 Mass Relative abundance 404.000
11.48 406.000 8.72 407.000 12.64 408.000
15.04 409.000 10.98 410.000 20.73 412.000
10.58 411.000 4.24 414.000 1.58 405.000
1.66 413.000 1.55 415.000 0.21 416.000
0.10 417.000 0.01 418.000 0.00
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Mo2O3detc4 Mo2S8O3N4C20H40 Accurate mass
831.970276 Mass Relative abundance 824.000
1.32 826.000 2.03 827.000 3.18 828.000
4.63 829.000 5.22 830.000 9.33 832.000
11.22 831.000 7.37 834.000 10.77 833.000
9.98 835.000 8.87 836.000 9.11 837.000
5.00 838.000 5.46 840.000 1.99 839.000
1.99 842.000 0.43 841.000 0.58 844.000 0.06
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MoOS2detc2 MoS6ON2C10H20 Accurate mass
471.931763 Mass Relative abundance 468.000
10.36 470.000 8.81 471.000 11.67 472.000
14.47 473.000 11.15 474.000 20.10 476.000
11.30 475.000 5.04 478.000 2.33 469.000
1.66 477.000 1.93 479.000 0.35 480.000
0.24 481.000 0.03 482.000 0.01 483.000 0.00
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