Matrix Isolation Method
2020/5/18
M2 Yuki Nishioka

Table of Contents• Introduction• History of Matrix Isolation Method• Application of Matrix Isolation Method• Summary2

Table of Contents• Introduction• History of Matrix Isolation Method• Application of Matrix Isolation Method• Summary3Introduction

What is Matrix Isolation?
・One of the method of observation unstablematerials
・George C. Pimentel developed in 1954.

inert material

active molecule4

George C. Pimentel et al. J. Chem. Phys. 1954, 22, 1943.

Introduction

George Claude Pimentel
1943: B.S. from University of California, Los Angeles
1949: Ph.D. from University of California, Berkeley
1949-1989: teaching at University of California,Berkeley

He was the inventor of the chemical laser.
・In low-temperature chemistry; he developed thetechnique of matrix isolation.
・In theoretical chemistry; he proposed the threecenter four-electron bond which is now accepted as
the best simple model of hypervalent molecules.
Source: https://www.asl-associates.com/Images/pimentel-george.pdf
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Table of Contents• Introduction• History of Matrix Isolation Method• Application of Matrix Isolation Method• Summary6

History of Matrix Isolation Method

Experimental Method
AgCl window
copperLiquid nitrogen orliquid hydrogen

Dewar bottle

George C. Pimentel et al. J. Chem. Phys. 1956, 25, 224.

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History of Matrix Isolation Method

Desirable Properties of Matrix
1. Inertness
2. Rigidity
3. Transparency
4. Volatility
George C. Pimentel et al. J. Chem. Phys. 1956, 25, 224.

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History of Matrix Isolation Method

Desirable Properties of Matrix
1. Inertness…………A rare gas is ideal. In N2 and ahydrocarbon cases, it depends on active molecules.
2. Rigidity……………The matrix must be sufficiently
rigid to prevent diffusion of the active species.

George C. Pimentel et al. J. Chem. Phys. 1956, 25, 224. 9

History of Matrix Isolation Method

Desirable Properties of Matrix
3. Transparency…. The matrix must have noabsorption in the spectral region of interest. Also,
glassy rather than a crystalline matrix is desirable.
4. Volatility………… The matrix must have a sufficiently
high vapor pressure at room temperature to permit
convenient handling of the gas in a vacuum line but asufficiently low pressure at the temperature of therefrigerant.
George C. Pimentel et al. J. Chem. Phys. 1956, 25, 224.

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History of Matrix Isolation Method

Application to Reaction Kinetics Analysis
・Matrix Isolation Method can also be used for reaction
kinetics analysis.
・It can be effectively used for a reaction having a heatof activation of 2 kcal or less.(e.g. isomerization, bondrupture and bond formation)

George C. Pimentel J. Am. Chem. Soc. 1958, 80, 62. 11

History of Matrix Isolation Method

Bring Together the Active Molecules
ArHNHHH↑0.1 degree/secondNHHHH

Ar / NH3 = 19540 ゜KNH

47.5 ゜K
After 75 seconds, spectra revealed thedisappearance of about 88 ± 6% of the monomer.
George C. Pimentel J. Am. Chem. Soc. 1958, 80, 62. 12

History of Matrix Isolation Method

Reaction Kinetics of Isomerization
N2H
N2H

N

O2N
N

NOhν
or13-30min

N2

N2 / HN3 / O2 = 500 : 1 : 0.520 ゜K

O

HOO

N

George C. Pimentel J. Am. Chem. Soc. 1958, 80, 62. 13

History of Matrix Isolation Method

Change in Absorbance

Cis form decreased
and trans form
increased.

cis formtrans form
George C. Pimentel J. Am. Chem. Soc. 1958, 80, 62. 14

History of Matrix Isolation Method

Calculating the Heat of Activation𝒌𝑇 ∆𝑆 0‡/𝑅 −Δ𝐻 0‡ /𝑅𝑇
𝑘1,2 =𝑒∙𝑒ℎ(1)

If equation 1 is applicable and ΔSǂ = 0, thedisappearance of the band at 865 cm-1 is governed bya process with a heat of activation of 1500 ± 130 cal.

George C. Pimentel J. Am. Chem. Soc. 1958, 80, 62. 15

History of Matrix Isolation Method

Short Summary
・Desirable properties of matrix
1. Inertness
2. Rigidity
3. Transparency
4. Volatility

・Application to Reaction kinetics analysis

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Table of Contents• Introduction• History of Matrix Isolation Method• Application of Matrix Isolation Method• Summary17

Application of Matrix Isolation Method

The Reactivity of 1,2-Azaborine

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Application of Matrix Isolation Method

Experimental Method

Klara Edel et al. Angew. Chem. Int. Ed. 2019, 58, 4061.

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Application of Matrix Isolation Method

Suggested Binding with COKlara Edel et al. Angew. Chem. Int. Ed. 2019, 58, 4061.

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Application of Matrix Isolation Method

The Computed Vibrational Spectrum

Klara Edel et al. Angew. Chem. Int. Ed.
2019, 58, 4061.
21

Application of Matrix Isolation Method

Suggested Binding with Xe

Klara Edel et al. Angew. Chem. Int. Ed. 2019, 58, 4061.

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Application of Matrix Isolation Method

The Computed Vibrational Spectrum

Klara Edel et al. Angew. Chem. Int. Ed. 2019, 58, 4061.

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Application of Matrix Isolation Method

Short Summary

In line with the character of the lowest unoccupied
molecular orbital of 1,2-azaborine, which is boron
centered and lies in the molecular plane, the boron
center preferentially acts as a Lewis acid towards
Lewis bases of variable strength (Xe, CO).

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Application of Matrix Isolation Method

Curtius Rearangement25Application of Matrix Isolation Method

Pseudo-Curtius Rearrangement
FVP…Flash Vacuum Pyrolysis

A; Calculated IR spectrum of PhS(O)2N3 atthe B3LYP/6-311++G(3df,3pd) level
B; The observed IR spectrum of PhS(O)2N3
in the solid Ne matrix at 2.8 K (absorbanceA, resolution 0.5 cm-1)

C; Raman spectrum of liquid PhS(O)2N3 at
298 K (Raman intensity I, resolution 2 cm-1).
Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 26

Application of Matrix Isolation Method

Analysis of Spectral Data

Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 27

Application of Matrix Isolation Method

Pyrolysis of Arylsulfonylazides
A; IR spectrum of PhS(O)2N3 in the solid Ne
matrix at 2.8 K.

B; IR spectrum of the flash vacuum
pyrolysis of PhS(O)2N3 in the solid Ne
matrix at 2.8 K.
C; IR difference spectrum showing thechange of the matrix containing flash
vacuum pyrolysis products of PhS(O)2N3upon visible light (λ = 380–450 nm, 20 W, 5min) irradiation.
d; PhNe; SO2Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 28

Application of Matrix Isolation MethodConsideration of Reaction Pathway

Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 29

Application of Matrix Isolation Method

Photolysis of Arylsulfonylazides

Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 30

Application of Matrix Isolation Method

Quantum Chemical Calculation

Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 31

Application of Matrix Isolation Method

Structure of Nitrene Intermediates

Guohai Deng et al. Phys. Chem. Chem. Phys. 2017, 19, 3792. 32

Application of Matrix Isolation Method

Short Summary

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Table of Contents• Introduction• History of Matrix Isolation Method• Application of Matrix Isolation Method• Summary34

Summary
・One of the method of observation unstable materials

・There are a lot of conditions that go into the choice ofthe matrix.
・Matrix isolation method can also be applied toreaction kinetics analysis.
・In combination with quantum chemical calculation,
the detailed reaction pathways can be revealed.
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