Complete multinuclear magnetic resonance analysis of heterophospholanes and their sulfur, selenium and borane adducts

Article abstract of DOI:10.1002/mrc.817

¹H, ¹¹B, ¹³C, ¹⁵N, ³¹P and ⁷⁷Se NMR spectra were obtained for 1,3-(dioxa, oxaza or diaza)-2-phospholanes and their sulfur, selenium and borane adducts. The relative sign of the ³J(¹H, ³¹P)/2/(¹³C, ³¹P) coupling constants was found to be positive in the sulfur and selenium adducts for the methylene and methyl groups. Conversely, for the compound with a phosphorus lone pair and in the borane adducts this sign changes for the methylene groups. It was shown that the ³¹P NMR spectra recorded by the CPMG or INEPT-HEED pulse sequences can be used for observation of the ¹⁵N-³¹P coupling constants. In all the investigated compounds the spin-lattice relaxation of ³¹P is controlled by the spin-rotation mechanism. The dipole-dipole ³¹P-¹¹B interactions can provide less than 20% of the relaxation rate in compounds containing the BH3 group. The transverse ³¹P relaxation is dominated by the scalar contribution. Copyright

Full text of DOI:10.1002/mrc.817

MAGNETIC RESONANCE IN CHEMISTRY
Magn. Reson. Chem. 2001; 39: 187–193
Complete multinuclear magnetic resonance analysis of
heterophospholanes and their sulfur, selenium and
borane adducts
Javier Peralta-Cruz,† Vladimir I. Bakhmutov and Armando Ariza-Castolo∗
Centro de Investigacio´ n y de Estudios Avanzados del IPN, Apartado Postal, 14-740 Me´ xico D.F, Mexico
Received 29 August 2000; Revised 2 November 2000; Accepted 8 December 2000
1H, 11B, 13C, 15N, 31P and 77Se NMR spectra were obtained for 1,3-(dioxa, oxaza or diaza)-2-phospholanes
3
and their sulfur, selenium and borane adducts. The relative sign of the J(1H, 31P)/2J(13C, 31P) coupling
constants was found to be positive in the sulfur and selenium adducts for the methylene and methyl
groups. Conversely, for the compound with a phosphorus lone pair and in the borane adducts this sign
changes for the methylene groups. It was shown that the 31P NMR spectra recorded by the CPMG or
INEPT-HEED pulse sequences can be used for observation of the 15N–31P coupling constants. In all the
investigated compounds the spin–lattice relaxation of 31P is controlled by the spin-rotation mechanism.
The dipole–dipole 31P–11B interactions can provide less than 20% of the relaxation rate in compounds
containing the BH3 group. The transverse 31P relaxation is dominated by the scalar contribution. Copyright
 2001 John Wiley & Sons, Ltd.
KEYWORDS: NMR; 1H NMR; 11B NMR; 13C NMR; 15N NMR; 31P NMR; 77Se NMR; relaxation time; spin-rotation; scalar
coupling; spin-echo; phospholanes
relaxation times of 31P can vary over a wide range
and the dipole–dipole,7 spin–rotation,7e,g,h,8 or chemical
shift anisotropy mechanisms7d,9 dictate their values. The
transverse relaxation time is usually dominated by scalar
relaxation of the second kind via scalar coupling.10 In this
paper we report on T1, T2 relaxation studies of 1–12 and
show that the 31P spin–lattice relaxation is governed by the
spin–rotation mechanism. In addition, we demonstrate that
CPMG and INEPT-HEED pulse experiments can be used to
determine the 15N–31P coupling constants.
INTRODUCTION
The derivatives of 1,3-diheterodimethylaminephospholanes
1–12 (Scheme 1), as representatives of organophosphorus
compounds, attract the attention of chemists owing to
their structure1 and chemical reactivity.2 In addition to
31P, compounds 1–12 contain other magnetically active
nuclei and therefore they are interesting from the NMR
spectroscopic point of view. A systematic study of these
compounds will be useful for the creation of convenient NMR
tests1b,3 sensitive to their structure. It is obvious that such
a task requires detailed measurements of chemical shifts,
coupling constants and relaxation times and rationalization
of their dependences on structural and electronic factors. One
of these factors is the presence of the free electron pair at the
phosphorus atom in 1, 5 and 9 (and also its occupation in 2–4,
6–8 and 10–12), acting as an efficient transmitter of the C–P
spin–spin coupling.1c,d,4 It should be noted that in spite of
the numerous J(P,C) measurements,4a,b there have been few
reports on the absolute or relative signs5 of these constants.
The T1/T231P relaxation times and their variations play
a very important role in the quantitative analysis of 31P
NMR data.6 In spite of this circumstance, these NMR
parameters remain less popular3 than chemical shifts and
coupling constants. It has been found that the spin–lattice
RESULTS AND DISCUSSION
The NMR parameters obtained for 1–12 are collected in
Tables 1–5. Note that the spectral and physical properties
of 1,2a,b,4b,11 2,11h,12 5,1a,c,e,3c,11e 612 and 9,4b,13 are in good
agreement with previous studies.
The 13C NMR data in Table 1 show a remarkable influence
oftheheterocycleatomsonthechemicalshiftsoftheexocyclic
NꢀCH3ꢁ2 groups in 1, 5 and 9. It is seen that the NꢀCH3ꢁ2
resonance in the non-symmetrical oxazaphospholane 9 is
shifted to a low frequency. It is interesting that when the
phosphorus atom changes oxidation state, the chemical shifts
of the NꢀCH3ꢁ2 groups undergo fairly weak changes, the
direction of which depends of the nature of the heterocycle.
However, among compounds 2–4, 6–8 and 10–12 with the
occupied electron pair one can see the pronounced high-
field influence of the BH3 group. An opposite BH3 effect is
observed for endocyclic carbons C-2 while the C-3 resonance
ŁCorrespondence to: A. Ariza-Castolo, Centro de Investigacio´n y de
Estudios Avanzados de IPN, Apartado Postal, 14-740 Me´xico D.F.,
Mexico. E-mail: aariza@mail.cinvestav.mx
†On leave from Escuela Nacional de Ciencias Biolo´gicas del IPN.
DOI: 10.1002/mrc.817
Copyright  2001 John Wiley & Sons, Ltd.

188
J. Peralta-Cruz, V. I. Bakhmutov and A. Ariza-Castolo
Table 2. 1H chemical shifts, T1 and correlation times ꢀꢂcꢁ at
308 K
Compound
υ1H
T1 (s)
rH–H (A)a ꢂc (10ꢀ11 s)
1
CH2
CH2
CH3
3.79 3.55 š 0.05 1.782
4.08 3.88 š 0.21 1.782
2.84 2.31 š 0.21 1.788
1.05
0.97
1.65
5
9
CH2
CH2
2.88 2.79 š 0.21 1.772
1.30
1.18
0.76
0.74
3.17 3.08 š 0.16 1.772
Scheme 1
CH3 (exo) 2.54 2.48 š 0.11 1.783
CH3 (endo) 2.56 2.51 š 0.09 1.779
NCH2
NCH2
OCH2
OCH2
2.83 2.55 š 0.03 1.772
3.12 2.81 š 0.02 1.772
3.95 3.80 š 0.06 1.784
4.14 3.98 š 0.02 1.784
1.42
1.29
0.99
0.95
0.76
0.77
in non-symmetric compounds 10–12 is again shifted towards
high field by the BH3 group.
The 31C–31P coupling constants through two chemical
bonds in 1, 5 and 9 were found to be in good agreement with
previous reports.1a,5c,d The HETCOR experiments, carried
out for all the compounds, allowed the determination of
CH3 (exo) 2.44 2.45 š 0.07 1.779
CH3 (endo) 2.46 2.45 š 0.04 1.785
7
CH2
CH2
2.94 1.39 š 0.26 1.772
3.15 1.39 š 0.26 1.772
2.60
2.60
0.83
0.77
2
3
the relative signs of the J(PN,C) and J(PN,CH) constants
(see the Experimental section). It is well known that values
and signs of the 2J(PN,C) coupling constants are dictated
mainly by an orientation of the lone pair which acts as a
transmitter of the coupling.1a,4a Table 1 shows clearly that
CH3 (exo) 2.38 2.26 š 0.24 1.783
CH3 (endo) 2.67 2.40 š 0.02 1.779
4
8
CH2
CH3
BH3
4.26 4.16 š 0.07 1.823
2.37 3.84 š 0.25 1.835
1.12 1.40 š 0.13 1.963
1.03
0.58
2.39
2
all the J(PN,C) values in 1 decrease significantly when the
phosphorus electron pair is occupied by S, Se and B atoms.
More complicated tendencies are observed for 5, 9 and their
S, Se and BH3 adducts. Here the 2J(PN,C) constants for
atoms C-1 and C-4 decrease whereas those for C-2 and C-3
can change sign or even increase depending on the nature of
the ring.
CH2
CH2
2.99 4.61 š 0.02 1.798
0.86
0.86
0.38
0.33
3.61
3.15 4.61 š 0.02 1.798
CH3 (exo) 2.45 5.87 š 0.01 1.833
CH3 (endo) 2.55 6.36 š 0.03 1.812
BH3
1.13 1.48 š 0.02 1.891
12
NCH2
NCH2
OCH2
OCH2
3.09 4.25 š 0.08 1.794
3.22 4.25 š 0.08 1.794
4.11 5.12 š 0.02 1.822
4.17 5.12 š 0.02 1.822
0.92
0.92
0.84
0.84
0.37
0.39
2.23
The 1H NMR spectra (Table 2) exhibit AA0BB0X and
ABCDX patterns ꢀX D 31Pꢁ of the methylene protons in
the symmetric and non-symmetric compounds, respectively.
CH3 (exo) 2.43 5.77 š 0.02 1.835
°
Borane adducts 4, 8 and 12 show (at 30 C) four typical
CH3 (endo) 2.39 6.02 š 0.05 1.835
BH3 resonances with 1Jꢀ1H, 11Bꢁ values of 97.2, 96.0 and
96.3 Hz, respectively. Each component of the signals is
additionally splitting into a doublet by the 31P–B–1H
BH3
1.14 1.20 š 0.29 1.891
a Estimated by PM3 for 1, 5, 7 and 9 and by AM1 for 4, 8 and 12.
Table 1. 13C chemical shifts and two-bond coupling constants 2Jꢀ13C, 31Pꢁ (Hz)
C-1 C-2 C-3
C-4
Compound
υ
13C
2JꢀC, Pꢁ
υ
13C
2JꢀC, Pꢁ
υ
13C
2JꢀC, Pꢁ
υ
13C
2JꢀC, Pꢁ
1
2
3
4
5
6
7
8
9
35.00
C19.5a,b
64.37
65.90
65.54
67.81
53.38
47.99
47.82
49.93
66.69
64.83
64.49
65.81
ꢀ8.6a,c
<1.5
<1.5
3.6c
64.37
65.90
65.54
67.81
53.38
47.99
47.82
49.93
50.08
49.41
48.91
48.85
ꢀ8.6a,c
<1.5
<1.5
3.6c
37.04
37.09
34.83
37.44
37.22
37.26
36.03
35.15
37.34
36.89
35.51
4.9b
4.9b
6.9b
C16.6b,d
ꢀ8.9c,d
ꢀ8.9c,d
34.78
31.82
32.25
32.08
31.54
31.63
32.08
31.7
C23.5b,d
2.9b
4.9b
9.8b
9.8b
8.8b
1.5
<1.5
13.3b
13.8b
8.6b
4.9b
8.8b
6.8b
3.8b
1.5c
8.5b
C17.7a,b
ꢀ11.5a,b
C23.8a,b
10
11
12
3.1b
2.1b
5.4b
5.0b
3.6c
6.2b
4.9b
7.2c
9.6b
a Coupling constant absolute sign was reported previously. 4b
b 3Jꢀ31P, 1Hꢁ/2Jꢀ31P, 13Cꢁ > 0 (positive tilt in 13C/1H HETCOR).
c 3Jꢀ31P, 1Hꢁ/2Jꢀ31P, 13Cꢁ < 0 (negative tilt in 13C/1H HETCOR).
d Coupling constant absolute sign was reported previously.1a
Copyright  2001 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2001; 39: 187–193

NMR of heterophospholanes and adducts
189
Table 3. 77Se and 11B chemical shifts and 31P coupling constants
Compound
υ
77Se
1Jꢀ31P, 11Seꢁ
Compound
υ
11B
1Jꢀ31P, 11Bꢁ
T111B (ms)
3
7
11
ꢀ317.15
ꢀ325.56
ꢀ313.68
953.9
824.7
959.2
4
8
12
ꢀ41.8
ꢀ41.7
ꢀ42.4
93.3
95.8
95.7
20.6 š 0.1
28.3 š 0.1
23.6 š 0.1
Table 4. 31P NMR data at 308 K
SC
DD
Compound
υ
31P
T1 (s)
T2 (s)
T2 (s)
T1 ꢀ1Hꢁ (s)
1
141.88a
10.2 š 0.1
6.8 š 0.3b
13.3 š 0.3
10.5 š 0.2d
7.0 š 0.05e
9.6 š 0.2f
0.043 š 0.002
0.043 š 0.002
1792 š 100
2
3
89.74c
91.11
0.47 š 0.08
5.69 š 0.3d
0.48 š 0.08
12.4 š 1d
233 š 11
99 š 5
4.88 š 0.2e
16.1 š 2e
4
5
133.50
110/11B D ꢀ9.2
ppb
0.042 š 0.002f
0.042 š 0.002f
47 š 3
6.3 š 0.2b
11.8 š 0.4g
11.8 š 0.1
10.5 š 0.1b
13.5 š 0.5
9.5 š 0.3d
9.3 š 0.2e
11.5 š 0.3f
8.6 š 0.3b
12.4 š 0.4g
10.7 š 0.03
8.3 š 0.2b
12.7 š 0.6
11.4 š 0.2d
11.7 š 0.3e
11.06 š 0.04f
7.7 š 0.2b
11.3 š 0.3g
0.075 š 0.002g
0.01 š 0.0005
0.075 š 0.002g
0.01 š 0.0005
115.26h
242 š 12
6
7
80.69
79.58
0.57 š 0.03
4.35 š 0.2d
0.59 š 0.03
8.0 š 0.6d
207 š 16
73 š 4
4.35 š 0.2e
8.1 š 0.6e
8
9
104.76
110/11B D ꢀ9.8
ppb
0.063 š 0.003f
0.063 š 0.003f
471 š 28
0.101 š 0.005g
0.01 š 0.0005
0.102 š 0.005g
0.010 š 0.0005
133.69i
62.6 š 4
10
11
88.59
89.13
0.84 š 0.001
2.75 š 0.1d
0.899 š 0.002
3.62 š 0.2d
142 š 18
140 š 7
2.69 š 0.1e
3.49 š 0.2e
12
118.9
110/11B D ꢀ10.7
ppb
0.038 š 0.001f
0.038 š 0.001f
45.3 š 4
0.055 š 0.002g
0.055 š 0.002g
a In agreement with Refs 11b–e.
b At 338 K.
c In agreement with previous report.12
d Main signal.
e 31P–77Se satellite.
f 31P–11B.
g 31P–10B.
h In agreement with Refs 3c, 11e.
i In agreement with Ref. 11e.
coupling with 2Jꢀ1H, 31Pꢁ D 17.8, 16.7 and 19.1 Hz for 4, 8
and 12, respectively.14 The appearance of these well resolved
resonances is explained by the fairly long T1 relaxation times
of 11B (Table 3).
In accord with Letcher and van Wazer’s15 explanation, the
31P resonance of dioxaphospholane is considerably shifted
with respect to oxazaphospholane and diazaphospholane
(Table 4). Although the S and Se adducts show similar
chemical shifts, their 31P lines are shifted to low frequency
by 49, 44 and 34 ppm with respect to 1, 5 and 9. The effect of
the BH3 group is significantly less and lies between 6.8 and
14.8 ppm.
12 are characteristic, demonstrating the relatively weak
dependence of the nature of the heterocycle. The 1Jꢀ77Se, 31Pꢁ
constants >820 Hz correspond to the P Se double bond.
Identically, the 1Jꢀ11B, 31Pꢁ constants >90 Hz indicate well
the presence of a strong coordination bond.14a Finally, the
modification of the parameters of 15N NMR on going from 1
and 5 to their S, Se and BH3 adducts can be found in Table 5.
Here the results of measurements of the 1Jꢀ31P, 15Nꢁ coupling
constants are of the greatest interest. The comparison of
adducts 2 and 4 or 6 and 7 shows that the 1Jꢀ31P, 15Nꢁ value in
the exocyclic fragments depends reasonably on the nature of
the atom bonding with phosphorus. However, the similarity
of these exocyclic constants in 5 and 6 seems surprising.
Actually, this result demonstrates that the phosphorus lone
As can be seen from Table 3, the chemical shifts of
the 77Se and 11B nuclei in adducts 3, 4, 7, 8, 11 and
Copyright  2001 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2001; 39: 187–193

190
J. Peralta-Cruz, V. I. Bakhmutov and A. Ariza-Castolo
Table 5. 15N chemical shifts and one-bond coupling
constants 1Jꢀ15N, 31Pꢁ (Hz)
where 1/T1(H–H) (s) is the relaxation rate for the methylene
protons and r(H–H) (A) is the distance between them.
˚
The H–H distances can be found by PM317 or AM118
calculations and the ꢂc values determined by this approach
are presented in Table 2. It should be noted that the
correlation times for the different methylene protons differ
insignificantly, showing a practically isotropic character of
molecular motions. However, the T1 data of the methyl
protons give the reduced ꢂc times due to the well known
internal fast rotation of the CH3 group.19 For 4, containing
the BH3 group, the relaxation measurements provided an
average ꢂc value of 1.03 ð 10ꢀ11 s. On the basis of this value
υ
15N
1Jꢀ15N, 31Pꢁ
υ
15N
1Jꢀ15N, 31Pꢁ
Compound (endocyclic)
(exocyclic)
1
2
4
5a
6
ꢀ339.61
ꢀ301.56
ꢀ297.26
ꢀ334.75
ꢀ323.80
ꢀ340.30
ꢀ324.10
90
70
98
90
89
71
89
ꢀ343.90
ꢀ327.27
52
51
7
9b
n.o.c
ꢀ334.00
51
˚
and rꢀP–Bꢁ D 1.7 A (AM1 calculation), Eqn (2) leads to a
a In agreement with Ref. 3c.
b In agreement with Ref. 4b.
c Not observed.
1/T1ꢀ31P–11Bꢁ relaxation rate of 0.0205 sꢀ1. In turn, this value
corresponds well to the difference in the 31P relaxation rates,
measured for the 11B and 10B satellites (Table 4). It should
be noted that in the last case the 31P–10B interactions are
negligible because of the lower magnetogyric ratio of 10B.
Thus even in the compounds containing the BH3 group, the
dipole–dipole mechanism can provide less than 20% of the
relaxation rate of 31P.
pair in 5 does not play a significant role in the one-bond P–N
coupling, which is rather dictated by geometric factors.1a,4b
In addition, the 1Jꢀ31P, 15Nꢁ constants in the rings of both
compounds are also identical.
Table 4 lists the 31P spin–lattice and spin–spin relaxation
data collected for the investigated compounds. It can be seen
that the room temperature T1 values remain within a fairly
narrow range between 9.3 and 13.5 s whereas the T2 times
change significantly from 0.01 s in 5 and 9 to 5.7 s in 3.
The small variation in T1 is dictated by similar moments
of inertia of the molecules and reflects the same relaxation
mechanism for all the compounds. It is well known that the
31P T1 relaxation rate can be governed by dipole–dipole,7
spin-rotation8 and chemical shift anisotropy contributions.9
The last contribution, being proportional to the square of
the magnetic field used, can be ruled out because the T1
measurements at 6.3 and 9.3 T gave almost identical results.
The 31P NMR spectra, recorded in the presence and absence
A significant scalar contribution to the 31P T1 time
has been reported for the phosphorus ligands binding to
Re.20 This mechanism was operating effectively due to the
exceptionally large 1J(P,Re) values and the very short T1
times of rhenium quadrupolar isotopes. It is obvious that
this scalar mechanism cannot operate in the case quadrupole
nuclei such as 14N and 11,10B. Note that the 11B nuclei in
4, 8 and 12 showed moderately short T1 times between
0.021 and 0.028 s. Taking into account all the data, one can
suggest that the spin–lattice relaxation rate of 31P in all the
investigated compounds is controlled by the spin-rotation
mechanism.16c,19,21 In full accord with this proposition,
the relaxation rate increases significantly with temperature
(Table 4).
It follows from the data in Table 4 that the transverse
relaxation time, being significantly shorter than T1, changes
strongly on going from one compound to another. This fea-
ture can be attributed to the mechanism of scalar relaxation
of the second kind ꢀT2SCꢁ.10 According to Mlyna´rik,10b the
scalar contribution to T2 is given by
1
of f Hg irradiation, showed negligibly small NOE values
and thus the 31P relaxation due to phosphorus–proton
dipole–dipole interactions can be also ruled out. It is obvious
that the dipole–dipole 31P–14N contribution16
1
0.019 ð 1011ꢂc
D
ꢀ1ꢁ
T1ꢀ31P–14Nꢁ
rꢀP–Nꢁ6
˚
where r is in A is not effective because of the small value
of the magnetogyric ratio of 14N. Actually, for example,
the T1ꢀ31P–14Nꢁ value in 1 is calculated as ¾1600 s if the
1
1
T2
1
T1
D
ꢀ
ꢀ4ꢁ
T2SC
17
˚
It should be noted that a reason for the operation of this
mechanism for all the compounds could be the presence of
the 14N quadrupole nuclei. In such a case the largest scalar
contribution should be expected for 5 and 9, containing more
than one nitrogen atom. Indeed, these compounds show
the shortest T2SC times (see Table 4). It is interesting that the
scalar contribution to the T2 relaxation rate decreases in the S
and Se derivatives and increases again in the boron adducts.
These results can be explained in terms of the variation in the
T1 times of the 14N nuclei because the Jꢀ31P, 14Nꢁ coupling
constants change insignificantly (see Table 5).
r(P–N) value is taken as 1.78 A from a PM3 calculation.
Note that the ꢂc value of 10ꢀ11 s can be determined
from the 1H T1 relaxation measurement (see below).
Theoretically, a remarkable contribution to the total 31P
relaxation rate could be expected only for 4, 8 and 12 owing
to 31P–11B dipole–dipole interactions. The corresponding
contribution16 is expressed by
1
0.48 ð 1011ꢂc
D
ꢀ2ꢁ
T1ꢀ31P–11Bꢁ
rꢀP–Bꢁ6
The correlation times ꢂc for molecular motions of 1, 4, 5, 7,
8, 9 and 12 are easily estimated from the H T1 relaxation
measurements on the basis of the equation
1
Finally, we found that the 15N–31P coupling constants
can be observed directly in the 31P NMR spectra of the
compounds, containing one nitrogen atom, using for the
first time the CPMG or in agreement with Kupcˇe and
1
8.55 ð 1011ꢂc
D
ꢀ3ꢁ
T1ꢀH–Hꢁ
rꢀH–Hꢁ6
Copyright  2001 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2001; 39: 187–193

NMR of heterophospholanes and adducts
191
86.55 MHz (spectral width 17 241.4 Hz, acquisition time
°
0.475 s, pulse width 75 , 64 scans, recycle delay 0.5 s.
1
13Cf Hg NMR spectra were recorded at 67.80 MHz (spec-
tral width 12 224.9 Hz, acquisition time 1.34 s, pulse width
1
30 , 128 scans, recycle delay 0.8 s). The 15Nf Hg NMR spectra
°
were obtained by the INEPT method,24 using a Jꢀ15N, 1Hꢁ
2
value of 2.5 Hz (spectral width 16 393 Hz, recycle delay
1
4 s, acquisition time 0.999 s). 31Pf Hg NMR spectra were
obtained at 109.37 MHz (spectral width 21 881.8 Hz, acqui-
°
sition time 1.4981 s, pulse width 60 , recycle delay 0.4 s,
1
64 scans). 77Sef Hg NMR spectra were recorded at 51.50 MHz
(spectral width 40 000.0 Hz, acquisition time 0.41 s, pulse
°
width 30 , recycle delay 0.1 s, 256 scans).
Relative signs of the coupling constants [3Jꢀ31P,
1Hꢁ/2Jꢀ31P, 13Cꢁ] were determined via 2D 13C/1H
heteronuclear shift correlations (HETCOR), observing the
positive (alike signs) or negative tilt (opposite signs)
of the cross peaks in the contour plot.25 The 1H, 11B
and 31P spin–lattice relaxation times were measured by
the inversion–recovery method with continuous proton
decoupling at 308 K (for the 1, 4, 5, 8, 9 and 12 we recorded
the T1 of 31P also at 338 K), using recycle delays greater than
five times T1 and at least 10 variable delays, eight scans
(spectral width 2000 Hz, 1024 data points for 31P, spectral
width 10 862 Hz, 1024 data points for 11B and spectral width
4053 Hz, 8192 data points for 1H).
Transverse relaxation times ꢀT2ꢁ were measured by the
Carr–Purcell–Meiboom–Gill sequence26 with continuous
proton decoupling at 308 K, using recycle delays greater
than five times T1 and at least 10 variable delays, eight scans,
spectral width 2000 Hz, 1024 data points and two different
values of ꢂꢀꢂ D 2.5 and 1 ms for 1, 2, 4, 5, 6, 8, 9, 10 and 12
and ꢂ D 0.1 and 0.05 s for 3, 7 and 11). The T1 and T2 values
were calculated by a non-linear fitting procedure using the
peak intensities (errors <5%). All the 1H, 11B and 31P pulses
were calibrated prior to acquisition.
Figure 1. (a) T2 measurement of compound 1. The delays are
10–120 ms and ꢂ D 1 ms. In the inset, the broad residual signal
of the 31Pꢀ14Nꢁ isotopomer and the sharp doublet of the
31Pꢀ15Nꢁ isotopomer are already clearly visible. (b) Top, 31
INEPT-HEED (Hahn-echo delay, 50 ms; recycle delay, 4 s;
acquisition time, 1 s; total detection time, 5 min); bottom,
P
NOEs were obtained from the increase in the signal
intensity when proton broadband decoupling was used
compared with when it was absent. A recycle delay of 10
times T1 was used to ensure complete relaxation of the 31P
magnetization. The accuracy of the NOE was better than 10%.
The 31P INEPT-HEED spectra were collected using
Hahn-echo extended pulse sequence22 with the parameters
presented in Fig. 1.
1
31Pf Hg NMR spectrum.
Wrackmeyer22 the INEPT-HEED pulse sequences (Fig. 1)
under the conditions T2 − T1.
EXPERIMENTAL
The 31P NMR spectra at 9.4 T were recorded on a JEOL
Eclipse C400 spectrometer,
Spectra
The electron ionization (EI) mass spectra (70 eV) were
recorded using a Hewlett-Packard HP-5998A spectrometer.
Compounds
The 1H, 13Cf Hg, 11Bf Hg, 77Sef Hg, 31Pf Hg and 15Nf Hg
NMR spectra were recorded with a JEOL DELTA-GSX-270
spectrometer equipped with a 5 mm multinuclear probe,
using O2-free23 benzene-d6 solutions (0.2 mmol of the com-
pound per 0.4 ml of C6D6). The chemical shifts are referenced
1
1
1
1
1
The synthetic work and the handling of NMR samples were
carried out in an inert atmosphere ꢀN2ꢁ. BH3 Ð THF was
prepared as reported.27
Compounds 1, 5 and 9 were prepared by a standard
method.28 The phospholanes were formed on reaction
of [ꢀCH3ꢁ2N]3P with the appropriate diol, diamine or
amino alcohol derivatives under reflux for 2 h, using
tetrahydrofuran as the solvent.
to internal ꢀCH3ꢁ4Siꢀυ1H D 0, υ13C D 0ꢁ, neat CH3NO2ꢀυ 15
N
for 15 N D 10.136767 MHz), ꢀC2H5ꢁ2O Ð BF3ꢀυ11B, 11B D
32.083 972 MHz), 85% H3PO4ꢀυ31P, 31P D 40.480 747 MHz),
neat ꢀCH3ꢁ2Se ꢀυ77Se, 77Se D 19.071 252 3 MHz). 1H NMR
spectra were recorded at 270.05 MHz (spectral width
1
2700 Hz, acquisition time 1.516 s, pulse width 45 , 32 scans,
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.84 d [C8.3] 6H, 3.79 m [C8.6]
°
recycle delay 2 s). 11B NMR spectra were recorded at
2H, 4.08 m [C4.4] 2H, [2JꢀH,Hꢁ D ꢀ8.6, 3JꢀH,Hꢁ D C7.0 cis,
Copyright  2001 John Wiley & Sons, Ltd.
Magn. Reson. Chem. 2001; 39: 187–193

192
J. Peralta-Cruz, V. I. Bakhmutov and A. Ariza-Castolo
3JꢀH,Hꢁ D C6.3 trans]. El-MS, m/z (%) 135 (71) [MC], 91 (100),
[2JꢀH,Hꢁ D ꢀ8.1 NCH2, 2JꢀH,Hꢁ D ꢀ9.1 OCH2, 3JꢀH,Hꢁ D
C8.9 cis, 3JꢀH,Hꢁ D C7.4 trans]. El-MS, m/z (%) 231 (0.4), 230
(5.2), 229 (2.5), 228 (28), 226 (14), 225 (5.2), 224 (5.5), 222 (0.5),
184 (2.4), 148 (34), 104 (100), 56 (30), 42 (28).
75 (26), 43 (68), 45 (60).
5
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.54 d [C7.2] 6H, 2.56 d [7.2] 6H,
2.88 m [C8] 2H, 3.17 m [C4.5] 2H [2JꢀH,Hꢁ D ꢀ8.4, 3JꢀH,Hꢁ D
C6.9 cis, 3JꢀH,Hꢁ D C5.7 trans]. El-MS, m/z (%) 161 (32) [MC],
117 (100), 74 (14), 60 (15), 42 (4).
Borane adducts 4, 8 and 12
The borane adducts were prepared from the reaction of
borane–tetrahydrofuran and the phospholane in equimolar
°
proportions at 0 C. The solvent was evaporated under
vacuum 5 min after the borane addition. The reactions gave
quantitative yields.
9
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.44 d [C8.7] 6H, 2.46 d
[C12.3] 3H, 2.83 m [C7.5] 1H, 3.12 m [C4.3] 1H, 3.95 m
[C4.3] 1H, 4.14 m 1H [2JꢀH,Hꢁ D ꢀ6.9 NCH2, 2JꢀH,Hꢁ D
4
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.37 d [9.8] 6H, 4.26 m [9.5]
2H, 4.39 m [4.8] 2H, [2JꢀH,Hꢁ D ꢀ8.0, 3JꢀH,Hꢁ D C9.0 cis,
3JꢀH,Hꢁ D C6.6 trans]. El-MS, m/z (%) 149 (22), 109 (100), 91
(57), 78 (11.7), 41 (36.6).
ꢀ7.76 OCH2, 3JꢀH,Hꢁ D C7.7 cis, JꢀH,Hꢁ D C7.4 trans]. El-
3
MS, m/z (%) 148 (5) [MC], 117 (100), 106 (9), 74 (14.8), 60 (35),
44 (66.9).
Sulfur and selenium adducts 2, 3, 6, 7, 10 and 11
Solutions of 3.1 mmol of the phospholane in 0.5 ml of
tetrahydrofuran were treated with 3.1 mmol of sulfur or
selenium. The mixture was stirred at room temperature for
5 min and after the solvent had evaporated under vacuum,
pure ꢀ>95%ꢁ adducts were obtained.
8
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.45 d [12.0] 6H, 2.55 d [11.7] 6H,
2.99 m [9.3] 2H, 3.15 m [6.1] 2H [2JꢀH,Hꢁ D ꢀ8.4, 3JꢀH,Hꢁ D
3
C6.9 cis, JꢀH,Hꢁ D C5.7 trans]. El-MS, m/z (%) 175 (2), 174
(3), 157 (9.1), 131 (23.3), 117 (34.3), 101 (25), 57 (100).
12
2
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.43 d [9.7] 6H, 2.39 d [9.9]
3H, 3.09 m [5.5] 1H, 3.22 m [4.1] 1H, 4.11 m [8.2]
1H, 4.17 m [7.1] 1H, [2JꢀH,Hꢁ D ꢀ8.6 NCH2, 2JꢀH,Hꢁ D
ꢀ9.2 OCH2, 3JꢀH,Hꢁ D C8.6 cis, 3JꢀH,Hꢁ D C5.9 trans]. El-
MS, m/z (%) 162 (11), 161 (4), 148 (53.8), 104 (100), 60 (44),
42 (33).
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.54 d [3.9] 6H, 3.43 m [14.2]
2H, 3.70 m [8.5] 2H, [2JꢀH,Hꢁ D ꢀ8.8, 3JꢀH,Hꢁ D C7.3 cis,
3JꢀH,Hꢁ D C6.3 trans]. El-MS, m/z (%) 167 (70) [MC], 134 (68),
91 (100).
3
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.46 d [12.3] 6H, 3.40 m [14.1]
2H, 3.67 m [8.5] 2H, [2JꢀH,Hꢁ D ꢀ8.8, 3JꢀH,Hꢁ D C7.3 cis,
3JꢀH,Hꢁ D C6.3 trans]. El-MS, m/z (%) 218 (1), 217 (7), 216 (5),
215 (40), 213 (19), 212 (7), 211 (7), 209 (1), 134 (47), 91 (100).
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1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.38 d [12.4] 6H, 2.67 d [11.5] 6H,
2.94 m [7.1] 2H, 3.15 m [11.2] 2H, [2JꢀH,Hꢁ D ꢀ8.4, 3JꢀH,Hꢁ D
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(100).
10
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.42 d [11.1] 6H, 2.53 d [11.6] 3H,
2.83 m [3.9] 1H, 2.95 m [18.5] 1H, 3.81 m [3.0] 1H, 3.83 m [7.1]
1H [2JꢀH,Hꢁ D ꢀ8.0 NCH2, 2JꢀH,Hꢁ D 7.6 OCH2, 3JꢀH,Hꢁ D
C8.1 cis, 3JꢀH,Hꢁ D C7.8 trans]. El-MS, m/z (%) 180 (18) [MC],
151 (25), 136 (46), 119 (6), 104 (60), 44 (100).
11
1H NMR, υ1H[3Jꢀ1H, 31Pꢁ]: 2.50 d [11.5] 6H, 2.63 d [12.1] 3H,
3.15 m [3.8] 1H, 3.19 m [24.8] 1H, 4.16 m 1H, 4.21 m [12.8] 1H,
Copyright  2001 John Wiley & Sons, Ltd.
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