Copyright is owned by the Author of the thesis.  Permission is given for 
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the permission of the Author. 
 
r\ ::'lesis p?esentp1 in rn.rtial fulfilment 
of the reouirements for the degree of 
:Soctor of rhi losophy in -?'lemistry at 
;: a s s e .Y t' n i v e r s i t y ? 
ALA BOBERT FURNESS 
..,975 
I would like to thank my Supervisors, 
-r ?-?? Jol ley 8nd Dr l .D. Buckley, for their 
enthusiasm, nssi-tRnce and encouragement during 
the course of the ?ork summqrised in this thesis. 
I would also like to thank Dr G.1L Finder 
for his work in collAboration with Dr P.D. Buckley 
on the density matrix prorr'lrr.. 
Finally I th,nk the Unive?sity Grants 
Committee for t1e award of a post-graduate 
scholarship which enabled this study to be made. 
i i  
ABSTRACT 
Density  mat rix theory has been used to deve lop  
a compute r  program for the  solution o f  a fou r-nuc lear 
spin  system . A de scription o f  the theory us ed to  
deve lop  this  program is given in Chapter Three . 
This theory has been  used  t o  study a range o f  
p??ubstituted  nitrosobenzenes .  The activation 
paramet e?s have been  det ermined and fo r 
N , N-dime thyl-p-n i t rosoaniline , a compari son has b een  
made with previous  studi e s  which  have used  more 
approximate  methods . 
The s o lvent dependency  o f  the barrier  t o  
ro t at ion  has been  invest igated  in  the 
N , N-dialkyl-p-nit rosoan i line s and no  s igni ficant  
s o lve nt dependence  found . 
iii  
In the  early s tage s of  this thesis , at t empts  we re 
m ade t o  find a t e t rahedral cob a lt (II)  complex  
invo lving l igand exchange,  but no such complex  suitab le 
fo r a d e tailed NMR inve s t igation was found . The 
i nve s t i gat ion ,  though unsucce s s ful,  has been  brie fly  
reported.  These  findings may aid further  work in  
this  are a . 
LIST OF CONTENTS 
Acknowledgements  
Abstract 
Li st  of  Contents  
List of Taoles 
Li s t  of Figures 
Lis t  of Symbols 
CHAPTER ONE: AN INTRODUCTION TO NUCLEAR MAGNETIC 
RE30NANCE 
1 . 1  
1 .2 
1 .3 
1 .4 
1.5 
1.b 
CHAPTRR TWO: 
2. 1 
2.2 
2. 2. 1 
2.2.2 
2.3 
2.3.1 
2.3.2 
2.3.3 
2.4 
2.5 
2.5. 1 
2.5.2 
2.6 
Nuclear Spin 
Chemical Shi fts  
Spin-spin Coupling 
The Spin Hami ltonian of the Multi- spin 
i System 
Re laxation 
;:;atu.ration 
TqE APP?IC?TION OF NMR TO KIN?TIC 
STUDIES INVOLVING INTRAMOLECULAR 
BXCHANGE 
Relaxation Mechanisms 
Thermodynamic Parameters of Intramol?
ecular exchange 
Determination of Ea and A 
Determination of  bR? and 4S? 
Intramolec ular Exchange 
Chemical Exchange 
Uncoupled Two-si te Case 
Chemical Exchange Considering Coupling 
The Use of Approximate  Equati ons  
''Approximate" Exchange Studi e s  
Internal Ro tation in N , N-dimethyl 
formamide 
Ring Inversion of  Cyclohexane 
?xperimental Problems in Exchange 
Page number 
ii 
iii 
iv 
Vii 
viii 
X 
1 
2 
3 
4 
6 
9 
1 1  
14 
1 6  
1 6  
1 7  
1 7  
18  
20 
22 
25 
25 
26 
29 
Page number 
CHAPTER THR.DE: THE DENSITY MATRIX METHOD APPLIED 
TO A FOUR-SPIN SYSTEM 
3.5 
3.6 
) .7  
3.d 
CHAPTER FOUR: 
4. 1 
4. 1 ? 1 
4. 1. 2 
4. 1. 3 
4.1.4 
4. 1. 8 
4.1.9 
4.1.10 
4.1.11 
4.1.12 
4.1.13 
4.1.14 
4.1.15 
Line Shape Calculations By the Density 
Matrix  Method 
lJensity Matrix 
Single Spin System 
Usefulness  of the Density Matrix Defin?
iti on 
'Nave Function and the Density Matrix  
Single Spin i Nuc leus 
Intramolecular ?xchange 
AB ?pin System Undergoing Internal 
Rotation 
Detailed Solution of  the AB System: 
Intramolecular Bxchange 
Strongly-coupled Four-si te Exchange 
System 
INTRAMO?CULAR BXCHANGE IN THE p?
SUBSTITUTED NITROSOBENZENES 
The N,N-dialkyl-p-nitrosoanilines 
lropertie s  of  the N , N-dialkyl-p-nitroso?
ani lines 
Preparation of Compounds 
Preparation of the Samples 
?olvents Used for the N,N-di alkyl-p?
nitrosoani lines 
?xperimental Conditions 
Meas uring Procedures 
Temperature Effects on the NMR Spectra 
of the N , N-dialkyl-p-nitrosoani!ines  
Temperature Measurements 
Frequency Measurements 
Analyses  of the Slow  Exchange Spectra 
The Exchange Rate 
?xperimental Matching of  the Density 
Matrix Spectra 
The Barrier  to Rotation 
Errors in the Activation Parameters 
Summary 
32 
33 
33 
35 
37 
39 
43 
44 
48 
52 
55 
56 
57 
59 
62 
63 
67 
68 
69 
70 
71 
76 
78 
86 
91 
97 
4.2 
4. 2. 1 
4.2.2 
4.2.3 
4.2.4 
4.2.5 
4.2.6 
4.2.7 
4.2.cl 
4.2.9 
4.3 
CHAPTER FIVE: 
5. 1 
5. 1 ? 1 
5. 1 ? 2 
5.2 
5. 2. 1 
5.2.2 
5.2.3 
5.3 
5 .) .  1 
5.).2 
5.).3 
5 . .;.5 
Appena.ix 1 
Appendix 2 
References 
The Anion Derived From p-nitrosophenol 
Purification of p-nitrosop?enol 
Preparation of NaOD 
Preparation of Samples 
Temperature Measurements 
Frequency Measurements 
Analysis of the dlow ?xchange Spectra 
The Bxchange Rate 
The Activation Parameters 
Summary 
Conclusions 
LIG??D ?ACHANG? IN COBALT (II) 
TETRAHEDRAL COMPLE?ES 
Phosphine Type Ligands 
Preparation of dichlorobis(diphenyl?
methylphosphine) Cobalt (II) 
Discussion 
The Li?and Trimethylarsine sulpnide 
Preparation of Trimethylarsine s?lphide 
Preparation of dihalobistrimethylarsine 
sulphide Cobalt (II) Complexes 
Discussion 
Pyrazole Type Ligands 
Preparation of ),5-dimethyl pyrazole 
?reparation of 1,),5-trimethyl pyrazole 
Preparation of 4-bromo-1,5,5-trimethyl 
pyrazole 
Preparation of ),5-dimethyl-1-phenyl 
pyrazole 
Attempted preparation of 1,4-dimethyl 
pyrazole 
Discussion 
Conclusions 
Page number 
100 
100 
101 
101 
102 
104 
104 
106 
10e 
109 
113 
117 
117 
117 
119 
119 
120 
120 
121 
121 
122 
124 
124 
125 
129 
131 
13} 
159 
163 
vi i 
LIST OF TABLBS 
Page number  
Table  1 . 1 Spin properties for a selec tion of  nuc lei  2 
Table 2.1 Thermodynamic parameters of cyclohexane 
obtained by different techniques 2 6  
Tab l e  4.1 ?olvents and solute  solubi lity 6 1 
Table  4.2 Chemi cal shifts  and coupling constants  
for the ring protons of  (1) and (2) in  
the slow exchange region 73 
Table  4.3  Rotati onal rates as a func tion of 
temperat ure for c ompound (1) and 
compound (2) in  acetone-d 6 80 
Table  4.4 Rotati onal rates  as a function of 
temperature  for c ompound (1) and 
c ompound (2) in chloroform-d1 82 
Table  4.5 dotati onal rate s  as a function of 
temperature for c ompound (2) in 
toluene-d8 84 
Table  4.6  Activation parameters for (1) anu (2) 89 
Table 4.7 Temperature gradi ents in  the sample tube 
in the JEOL JNM-C-60 HL probe at different 
temperatures for a gas flow pressure of 
50 g cm-2 93 
Table 4.8 Chemical shifts  and coupling constants 
for the ring protons  of  the anions of 
p-ni trosophenol  in 1 M K2C03 in the slow 
exchange region 105 
Table  4.9 Rotati onal rates  as a functi on of 
t emperature for a 7% w/v solution of 
p-ni trosophenol  107 
Table  4.10 Ac tivation parameters for the anion of 
p-ni trosopheno l in 1 M K2C03 110 
.Figure 2.1 
Figure 2.2 
F?gure 4.1 
Figure 4.2 
Figure 4.3 
Figure 4.4 
Figure 4.5 
Figure 4. 6 
Figure 4.7 
Figure 4.8 
LIST OF FIGURES 
Relaxati on mechanisms 
Experimental data for tne ro tation 
about the C-N bond in neat dimethyl 
formamia.e (D?lF). The numbers in  
square brackets are li terature 
references. 
The NMR spectrum of a sample of ethyl 
alcohol + TMS illustrating the use of 
fi eld frequency sweep 
NMR spectra of  N,N-diethyl-p-ni troso?
aniline as a 5% w/v soluti on in 
acetone-dh , taken at vari ous temp?
eratures  At 100 MHz 
The spectrum of N,N-dimethyl-p-ni troso?
aniline in the slow exchru1ge regi on. 
Tne slow exchange spectra of N,N-diethyl 
-p-nitrosoaniline in chloroform-d1 (A), and toluene-d8 (B) 
Bxample s  of experimental and theoret?
ical spectra for the H3,H5 nuclei of  
N,N-dimethyl-p-nitrosoaniline in 
acetone-d6 
Example s  of  experimental and theoret?
ical spectra for th? H2,li6 nucl?i of 
N,N-dimethyl-p-ni tro soaniline in 
acetone-d6 
Examples of  experimental and theoret?
ical spectra for the R3,R5 nuclei  of 
N,N-diethyl-p-ni tro soaniline in 
toluene-d8 
Example s  of experimental and theoret?
ical spectra for the H2,H6 nuclei of 
N,N-diethyl-p-nitrosoaniline in 
toluene-d8 
vii i  
After 
page number 
1 1 
24 
66 
67 
68 
69 
77 
78 
85 
86 
Figure 4.9 
Figure 4.10 
Figure 4.11 
Figure 4.J2 
Figure 4.13 
Figure 4.14 
F.igure 4.15 
Figure 5.1 
Figure 5.2 
Arrhenius plots for rotation about 
the Ar-NO bond of N,N-dimethyl-p?
nitrosoaniline in chloroform-d1 and 
acetone-d6 
Arrhenius plots for rotation about 
the Ar-NO bond of N,N-diethyl-p?
nitrosoaniline in chloroforrn-d (1), 
acetone-d6 (2), and toluene-dB (5) 
A comparison of Korver et al's data 
with this investigation's data for 
rotation about the Ar-NO bond of 
N,N-di?ethyl-p-nitrosoaniline in 
chloroform-d 
The variation of temperature in a 
spinning NMR sample tube at 353 K 
The spectrum of the anion of p-nitros? 
phenol, 7% w/v in D20 containing 
excess K2C03, in the slow exchange 
region 
?xamples of experimental and theoret?
ical spectra for the H3,H5 nuclei of 
the anio? of p-nitrosophenol in 
1 mol 1- K2C05 (in D20) 
Arrhenius plots for rotation about 
the Ar-NO bond of the anion of 
p-nitrosophenol in 1 M K2C03 (1) 
and NaOD (2) 
The observed chemical shift of the 
methyl protons versus the mole fraction 
of ligand for 0.05 mol 1-1 dichloro?
bis(diphenylmethyl phosphine) Cobalt(II) 
in deuterochloroform at room temperature 
The observed che?ical shift of the 
methyl protons versus th?1
mole fraction 
of ligand for 0.05 mol 1 dichloro?
bis(3,5-dimethyl pyrazole) Cobalt(II) 
After 
page number 
87 
90 
91 
94 
103 
108 
109 
1 17 
in deuterochloroform at room temperature 129 
Bo 
:81 
h 
# 
r+ I 
-
, 
IX, Iy' 
i 
I 
Jij 
Tr 
(J. B 
(i 
p 
p 0 0 lJ 
T, T _. 
w ' w 0 
Iz 
Li s t  of Symbols  
external magneti c  field in  the 
+ z direct i on 
X 
raC1i ol'requency magnetic  1oi eld 
Planck1s constant divided by 2? 
Hami ltonian , or Spin  Hamiltonian 
rai sing and lowering operators 
angular momentum operators in 
uni ts  of h/2'?7' 
Isotropi c  spin-spin c oupling 
constant between nuclei i and j 
in terms of linear frequency. I t  
i s  related  t o  Jij by the following 
expressi on , 1 2?Jij Jij 
::1 h 
Trace 
spin functions 
sheilding constant 
density  matrix 
the ijth e lement of the densi ty matrix 
mean lifetime  of the'nucleus .in  a 
given environment in unit soQf s rad-1 
and Hz-1 respectively . 
Transverse  relaxation time in unit s 
of s rad-1 and Hz-1 respectively . 
Longi tudinal relaxati on time in  units 
of  s rad-1 and Hz-1 respec tively . 
wave functions 
angular frequenci e s  
y 
f 
w r 
Magnetogyric ratio  
yB1/4n 
yB1 
tensor product 
Boltzmann const??t 
specific rotational rate 
equilibrium constant 
transmission coefficient 
angular frequency of proton at site A 
angular frequency of proton at site B 
to tal angular momentum in the y 
direction