Transcript MS Mass Spectrometry

MS
Mass Spectrometry
Organometallics
Centro de espectrometría de masa (Harvard)
General Information
The word that best describes the mass spectrometry of inorganic and
Organometallic molecules is "difficult".
Many species are intractable to mass spectrometry for one of a number of
reasons.
To see our recommendations for Organometallic, click here.
Recommendations
We recommend you confer with your friendly local mass
spectrometrist before preparing any organometallic or inorganic
samples for mass spectrometry.
Métodos de Ionización
(los más usuales)
• EI (Impacto Electrónico): se volatiliza la muestra y se ioniza con un
haz de electrones. M+. y fragmentos
• FAB (Fast Atom Bombardment): se coloca la muestra en una matriz
líquida (un alcohol) y se impacta con un haz de átomos de Xe.
(M+H)+; (M+Na)+, (M+matriz)+, fragmentos, etc
• MALDI (Matrix-Assisted Laser Desorption/Ionization): se coloca la
muestra en una matriz sobre un metal y se impacta con un laser. Muy
usado para péptidos y proteínas.
• ESI (ElectroSpray Ionization): se disuelve la muestra, se pasa por un
capilar a 5 kV, que la dispersa en microgotas. [M+nH]n+, [M+Na]+,
etc.
Isotope patterns
Aluminium Bromide:
AlBr+
27Al
: 100%
79Br : 51% 81Br : 49%
Isotope
patterns
63Cu35Cl
63Cu:
69.1%
65Cu: 30.9%
35Cl:
75.5%
37Cl: 24.5%
63Cu37Cl
65Cu35Cl
65Cu37Cl
Abundance of first isotope peak M: .691 x .755 = .521
For next isotope peak:
For next isotope peak:
M+2: .691 x .245 = .169
.309 x .755 = .233
M+4: .309 x .245 = .076
} .403
Poly-isotopic metals
Metal isotope pattern are distorted by 13C and 2H
Poly-isotopic metals
When more than one metal is present: pattern is affected in a
predictable way
Ru1
Ru2
(bpy)(tpy)RuN2ArN2Ru(bpy)(tpy)?
Reacciones ion-molécula
Se producen ocasionalmente, dando lugar a iones de MAYOR masa
que el ion molecular.
Cr(CO)6+ + Cr(CO)6 --> Cr(CO)10+ + 2 CO
Fragmentation
1. The charge is likely to remain on Metal-containing fragment
M Ln-1+ + L
MLn
L+ + M Ln-1
Less likely
2. Rearrangement involving hydrogen migration are frequent
R
(M => Si, Ge, Sn, Pb…)
R
R
M
M
H
H 2C
CH2
MeHC
O
R
H
R
R
M
R
O
M
H
R
CH3
H
Fragmentation
3. Migration of Halogens is very common
M (C6F5)3+
(C6F5)2 Sn F + + C6F4
M => Si, Ge, Sn, Pb
4. Migration of Alkyl to metal is also common
O
R
R
R
Fe
Fe
Fe
+
Transfer of R is influence by electronegativity of the R group
Rearrangement process
“McLafferty” type of rearrangement involving metal instead of H
MR 3
H 2C
+
MR 3
CH2
O
+
O
+
CH2
H 2C
CH2
R
H 2C
R
This rearrangement depends on readiness of metal to
become pentacoordinate (using it’s d-orbitals)
Metal Carbonyls (Co)
Metal Carbonyls (Fe)
Metal Carbonyls (Fe)
Carbonyl halide compounds
Terminal
Bridging
Carbonyl halide compounds
Terminal
Loss of CO and
X occur with
equal ease
Bridging
Loss of CO occur
stepwise with
retention of M2X2
than further X
loss can occur
Cs2IrCl5CO (ESI-MS(-))
IrCl4COamostra2 4 (0.081) Sb (5,40.00 ); Cm (3:53)
TOF MS ES1.34e4
360.8394
100
362.8295
IrCl4-
%
364.8250
IrCl5CO2-
358.8326
332.8458
336.8465
197.9033
330.8330
366.8259
199.9091
212.1047
230.1206
248.1298
0
m/z
195
200
205
210
215
220
225
230
235
240
245
250
255
260
265
270
275
280
285
290
295
300
305
310
315
320
325
330
335
340
345
350
355
360
365
370
MSMS 199 (IrCl5CO2-)
amostra2msms197 39 (0.782) Sb (5,40.00 ); Cm (36:82)
100
TOF MSMS 198.90ES109
198.9132
IrCl4CO362.8519
%
360.8618
IrCl4334.8647
332.8458
362.9862
0
m/z
195
200
205
210
215
220
225
230
235
240
245
250
255
260
265
270
275
280
285
290
295
300
305
310
315
320
325
330
335
340
345
350
355
360
365
370
FTMS
•
Fourier transform mass spectrometry, is a type of mass spectrometer for determining the
m/z of ions based on the cyclotron frequency of the ions in a fixed magnetic field.
•
The ions are trapped in a magnetic field with electric trapping plates where they are
excited to a larger cyclotron radius by an oscillating electric field perpendicular to the
magnetic field. The excitation also results in the ions moving in phase (in a packet). The
signal is detected as an image current on a pair of plates which the packet of ions passes
close to as they cyclotron. The resulting signal is called a free induction decay (FID),
transient or interferogram that consists of a superposition of sine waves. The useful
signal is extracted from this data by performing a Fourier transform to give a mass
spectrum.
complexo 3b tol terBUO com alcool #1 RT: 0,01 AV: 1 NL: 3,80E5
T: FTMS + p ESI Full ms [100,00-2000,00]
200
180
160
[Ru(CpPh5)]2BrO+
140
120
1189,1192 1191,1189
100
80
1187,1194
60
1192,1201
1186,1198
1193,1190
1185,1198
40
1197,1968
1196,1968
1184,1209
20
1179,4693
1182,1214
0
1178
1180
1182
1184
1186
1188
m/z
1190
1192
1194
1196
complexo 3b tol terBUO 20 min #1 RT: 0,01 AV: 1 NL: 3,43E4
T: FTMS + p ESI Full ms [370,00-2000,00]
120
[(CpPh5)Ru(CO)2]2(PhCH2O)+
110
1257,11
100
1258,11
1256,11
90
1259,11
80
70
1255,11
1260,11
1254,11
60
50
1261,11
1253,11
40
30
1262,11
1251,18
20
1251,71
10
0
1250
1252
1254
1256
m/z
1258
1260
1262
C79H57O3Ru2: C79 H57 O3 Ru2 pa Chrg 1
1259,24
100
1256,24
90
1257,24
1260,24
80
1254,24
70
60
50
40
1253,24
1261,25
1251,24
30
1262,24
20
1250,24
1248,24
1263,25
10
1264,25
1245,25
0
1245
1250
1255
1260
m/z
1265
1266,26 1268,26
1270