Conformational analysis and stereochemical dependences of 31P-1H spin-spin coupling constants of bis(2-phenethyl)vinylphosphine and related phosphine chalcogenides

Article abstract of DOI:10.1002/mrc.2386

Theoretical energy-based conformational analysis of bis(2-phenethyl) vinylphosphine and related phosphine oxide, sulfide and selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6-31IG** level

Full text of DOI:10.1002/mrc.2386

Research Article
Received: 13 October 2008
Revised: 5 November 2008
Accepted: 6 November 2008
Published online in Wiley Interscience: 6 January 2009
(www.interscience.com) DOI 10.1002/mrc.2386
Conformational analysis and stereochemical
dependences of 31P–1H spin–spin coupling
constants of bis(2-phenethyl)vinylphosphine
and related phosphine chalcogenides
Sergey V. Fedorov, Leonid B. Krivdin,∗ Yury Yu. Rusakov, Igor A. Ushakov,
Natalia V. Istomina, Natalia A. Belogorlova, Svetlana F. Malysheva,
Nina K. Gusarova and Boris A. Trofimov
Theoretical energy-based conformational analysis of bis(2-phenethyl)vinylphosphine and related phosphine oxide, sulfide and
selenide synthesized from available secondary phosphine chalcogenides and vinyl sulfoxides is performed at the MP2/6-311G∗∗
level to study stereochemical behavior of their 31P–1H spin–spin coupling constants measured experimentally and calculated
at different levels of theory. All four title compounds are shown to exist in the equilibrium mixture of two conformers: major
planar s-cis and minor orthogonal ones, while 31P–1 H spin–spin coupling constants under study are found to demonstrate
marked stereochemical dependences with respect to the geometry of the coupling pathways, and to the internal rotation of the
vinyl group around the P(X)-C bonds (X = LP, O, S and Se), opening a new guide in the conformational studies of unsaturated
c
phosphines and phosphine chalcogenides. Copyright ꢀ 2009 John Wiley & Sons, Ltd.
Keywords: NMR;31P–1Hspin–spincouplingconstants;SOPPA;SOPPA(CCSD);conformationalanalysis;vinylphosphines;vinylphosphine
chalcogenides
Introduction
on 77Se-1H spin–spin coupling constants. It was thus a gratifying
task to reveal if the same is true for 2J(P,H) and 3J(P,H) couplings
involvingtheprotonsofthefreelyrotatingvinylgroupsintheseries
of vinylphosphines and related vinylphosphine chalcogenides
under study.
Vinylphosphines and vinylphosphine chalcogenides are highly re-
activebuildingblockswhichinteractreadilywithdifferentreagents
(e.g. amines,[1] phosphines[2] and carbanion species[3]) to afford
functional phosphine chalcogenides. The latter are widely applied
as hemilabile ligands for the design of advanced catalysts,[4]
flame retardants,[5] extractants of rare earth and transuranic
elements,[6] and coordinating solvents for the synthesis of con-
ductive nanomaterials.[7] At the same time, known syntheses of
vinylphosphines and vinylphosphine chalcogenides are based on
hazardous phosphorus halides, vinyl derivatives of nontransition
metals (such as Li, Mg, Sn), multistep, laborious and solvent-
consuming procedures. Therefore, the development of facile
methods for the preparation of unsaturated phosphines and phos-
phine chalcogenides represents an urgent synthetic challenge.
One of the possible approaches to the synthesis of these com-
pounds may involve the reaction of available vinyl sulfoxides[8a]
with bis(2-phenethyl)phosphine chalcogenides, easily prepared
from red phosphorus and styrene in superbase systems.[8b]
Apart from synthetic interest, vinylphosphines and related
vinylphosphinechalcogenidesaretheattractivemodelsforsolving
important theoretical problems, especially those dealing with
stereochemical behavior of 31P–1H spin–spin coupling constants.
In particular, very recently,[9] the remarkable stereospecificity
of 2J(Se,H) and 3J(Se,H) in divinyl selenide with respect to the
internal rotation of both vinyl groups around the Se-C bonds has
been reported to avoid possible caveats dealings with erroneous
spectralassignmentsandmisleading structuralelucidationsbased
Results and Discussion
To obtain the desired set of vinylphosphine chalcogenides we
have studied the reaction of ethyl vinyl sufoxide with bis(2-
phenethyl)phosphine chalcogenides 1–3. The hydrophosphory-
lation proceeds in the system KOH–dioxane (40–70 ◦C) to give
bis(2-phenethyl)vinylphosphine chalcogenides 4–6 in 87, 91 and
31% yields, correspondingly (Scheme 1).
Apparently, the reaction involves initial formation of adducts
7–9 (data of 31P NMR), which further eliminate 1-ethanesulfenic
acid to afford vinylphosphine chalcogenides 4–6 (Scheme 2).
The corresponding bis(2-phenethyl)vinylphosphine (10) has
been obtained from vinylphosphine sulfide 5 or vinylphosphine
selenide 6 by their reduction under action of sodium in toluene
(Scheme 3).
∗
Correspondence to: Leonid B. Krivdin, A. E. Favorsky Irkutsk Institute of
Chemistry, Siberian Branch of the Russian Academy of Sciences, Favorsky
St. 1, 664033 Irkutsk, Russia. E-mail: krivdin office@irioch.irk.ru
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian
Academy of Sciences, Favorsky St. 1, 664033 Irkutsk, Russia.
c
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Conformational analysis of vinylphosphine and vinylphosphine chalcogenides
Scheme 1. Synthesis of bis(2-phenethyl)vinylphosphine chalcogenides 4-6.
Scheme 2. Formation route of bis(2-phenethyl)vinylphosphine chalcogenides 4-6.
in all calculations of probability density of population curves we
usedawell-approvedMP2/6-311G∗∗ levelofapproximationtaking
into account electronic correlation effects within the second-order
excitation theory and providing the most straightforward route to
the high-accuracy energy-based conformational analysis.
Potential energy curves of all four studied compounds 11–14
(Figs 1(a,c) and 2(a,c)) display three minima corresponding to one
planar s-cis conformer (A) and one twice-degenerated orthogonal
conformer (B), and four maxima corresponding to two each twice-
degenerated transition states (TS1 and TS2). Indeed, refining
minimum search in the regions of the expected stationary
points at the MP2/6-311G∗∗ level resulted in the localization
of two true-minimum conformers (A and B) and two transition
states (TS1 and TS2) for each of 11–14 shown in Figs 3 and 4.
Harmonic frequencies analysis revealed no imaginary frequencies
for the former (conformers) and showed one imaginary frequency
for each of the latter (transition states). Numerical integration
of the continuous probability density of population curves of
11–14 (Figs 1(b,d) and 2(b,d)) was used to determine the exact
conformational ratio of the true-minimum conformers of 11–14
subject to their degeneracies (Table 1). We used these data further
on for the conformational averaging of the calculated 31P–1H
spin–spin coupling constants in 11– 14.
Results of this theoretical energy-based conformational analysis
are generally in agreement with the available early[11] and
more recent[12] theoretical and experimental data for the
related compounds – unsaturated phosphines and phosphine
chalcogenides – demonstrating predominance of the planar s-cis
conformer in all cases, especially in phosphine chalcogenides as
comparedtophosphines. Wewillnotaddresstheseresultsinmore
detail because data presented in Figs 1–4 and in Table 1 are to
a great extent self-explanatory and require no further comments.
Moreover, the goal of the present energy-based conformational
analysis of 11–14 was not so much to perform it as itself
as to provide for the further high-level ab initio study of the
stereochemical behavior of 31P–1H spin–spin coupling constants
involving protons of the vinyl group attached to the phosphorus
atom bearing either lone pair (LP), as in 11, or the sp2 hybridized
chalcogen atom (O, S and Se), as in 12– 14.
Scheme 3. Synthesis of bis(2-phenethyl)vinylphosphine (10).
Prior to investigation of the stereochemical behavior of 2J(P,H)
and 3J(P,H) couplings in the series of vinylphosphines and
related vinylphosphine chalcogenides under study, theoretical
conformational analysis of dimethylvinylphosphine (11) and three
related phosphine chalcogenides (oxide, sulfide, and selenide)
12–14 has been carried out at the MP2/6-311G∗∗ level. As
compared to the experimentally studied set of compounds, 4–6
and10inthemodelstructures11–14, themethylgroupsattached
to the phosphorus atom were used instead of both phenethyl
groups. Also, the same set of model compounds 11–14 was used
furtheronintheoreticalcalculationsof 31P–1Hspin–spincoupling
constants to be compared with experimental couplings in 4–6
and 10.
Shown in Figs 1 and 2 are the rotational potential energy curves
of 11–14 together with the corresponding probability density
of population curves calculated on their basis. Full geometry
optimizations were carried out at the MP2/6-311G∗∗ level in
each rotational point of the potential energy curves incremented
with 10 degrees step. Probability density of population curves
were obtained from the numerical solution of the rotational
Schro¨dinger equation using the finite difference method applied
totheeigenvaluesandeigenvectorsproblemofthecorresponding
second-order differential equations, and the resulting set of
the found wavefunctions was averaged upon the calculated
energy eigenvalues using the Maxwell-Boltzmann distribution at
300 K; potential energies used in the one-dimensional rotational
Schro¨dinger equation were taken from the calculated potential
energy curves and approximated by the Fourier series while the
reduced moments of inertia were calculated from the optimized
equilibrium geometries, as described in Ref. [10]. Traditionally,
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S. V. Fedorov et al.
Figure 1. Rotational potential energy curves (a, c) and probability densities of population (b, d) of dimethylvinylphosphine (11) and dimethylvinylphos-
phine oxide (12) calculated at the MP2/6-311G∗∗ level. Values of φ = 0◦ are assigned to the s-cis arrangements of the vinyl group and either the
phosphorus lone pair in 11 or the P=O bond in 12, as shown.
Figure 2. Rotational potential energy curves (a, c) and probability densities of population (b, d) of dimethylvinylphosphine sulfide (13) and
dimethylvinylphosphine selenide (14) calculated at the MP2/6-311G∗∗ level. Values of φ = 0◦ are assigned to the s-cis arrangements of the vinyl
group and the P=X bonds (X = S, Se), as shown.
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Conformational analysis of vinylphosphine and vinylphosphine chalcogenides
Figure 3. Equilibrium structures of the localized true-minimum conformers and transition states of dimethylvinylphosphine (11) and dimethylvinylphos-
phine oxide (12) optimized at the MP2/6-311G∗∗ level. Relative energies are given in parentheses (kJ/mol).
All 31P–1H spin–spin coupling constants have been calculated
in 11–14 taking into account all four nonrelativistic coupling
contributions to the total coupling, J: Fermi contact, JFC, spin-
dipolar, JSD, diamagnetic spin-orbital, JDSO, and paramagnetic
spin-orbital, JPSO, at three different levels of theory, namely
within the DFT framework using the most popular Becke
three-parameter hybrid functional[13] with the Lee, Yang and
Parr[14] functional, B3LYP, and at the pure ab initio level using
the second-order polarization propagator approach (SOPPA),[15]
and that in combination with the coupled cluster singles
and doubles amplitudes approximation, SOPPA(CCSD).[16] Four
different Dunning-type correlation-consistent basis sets have
been used in all those calculations, namely double-zeta basis set
augmented with inner correlation core s-functions, cc-pCVDZ,[17]
double- and triple-zeta basis sets of Dunning et al.[18] with
decontracted s-functions and augmented with two tight s-
functions, accordingly, cc-pVDZ-su2 and cc-pVTZ-su2,[19] and
triple-zeta contracted basis set augmented with tight s-functions
and optimized for calculation of spin–spin coupling constants,
aug-cc-pVTZ-J.[20] From our earlier experience (see, for example,
recent review[21] and references given therein), all these basis sets
showed a rather good performance in calculations of spin–spin
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S. V. Fedorov et al.
Figure 4. Equilibrium structures of the localized true-minimum conformers and transition states of dimethylvinylphosphine sulfide (13) and
dimethylvinylphosphine selenide (14) optimized at the MP2/6-311G∗∗ level. Relative energies are given in parentheses (kJ/mol).
coupling constants of 13C-1H, 13C-13C and 15N-1H types in a
number of organic compounds at the SOPPA and DFT levels.
As an example, the latter, aug-cc-pVTZ-J, was successfully
employed very recently[9] in the state-of-the-art SOPPA calculation
of 77Se-1H couplings in divinyl selenide. So, the idea of the
present study was to test these methods and title basis sets
in the benchmark calculations of 31P–1H spin–spin coupling
constants in the model dimethylvinylphosphine (11) and three
related phosphine chalcogenides, 12–14, in comparison with
the experiment in the series of the four parent compounds,
accordingly, 10 and 4–6.
Experimental high-accuracy measurements of 31P–1H
spin–spin coupling constants in 4–6 and 10 were carried out
by the iterative high-order spectral analysis of the phosphorus-
coupled 1H NMR spectra, as illustrated in Fig. 5 for bis
(phenethyl)vinylphosphine sulfide (13). Iterative spin simulations
were performed in the framework of the four-spin systems ABCX
representing the three-spin ABC patterns in the phosphorus-
coupled 1H NMR spectra of three protons of the vinyl groups (HA,
HB and HX) and X-parts (additionally coupled with four protons of
two methylene groups) in the proton-coupled 31P NMR spectra of
4–6 and 10.
c
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Conformational analysis of vinylphosphine and vinylphosphine chalcogenides
Table 1. True-minimum conformers and transition states of dimethylvinylphosphine (11) and dimethylvinylphosphine chalcogenides (12–14)
localized at the MP2/6-311G∗∗ level
Population,b
%
Dihedral angle
Imaginary
Cmpd
Conformationa
Type
Degeneracy
Relative energy, kJ/mol
φ, Deg a)
frequency, cm−1
11
planar s-cis (A)
orthogonal (B)
TS1
Conformer
Conformer
1
2
2
2
1
2
2
2
1
2
2
2
1
2
2
2
61
39
–
0.0
2.5
0
–
–
110
63
Transition state
Transition state
Conformer
8.1
102.19
50.28
–
TS2
–
11.4
0.0
179
0
12
13
14
planar s-cis (A)
orthogonal (B)
TS1
91
9
Conformer
9.4
123
68
–
Transition state
Transition state
Conformer
–
13.9
10.8
0.0
88.75
4.72
–
TS2
–
178
0
planar s-cis (A)
orthogonal (B)
TS1
85
15
–
Conformer
7.5
121
65
–
Transition state
Transition state
Conformer
12.7
10.6
0.0
85.78
42.17
–
TS2
–
180
0
planar s-cis (A)
orthogonal (B)
TS1
90
10
–
Conformer
8.0
120
67
–
Transition state
Transition state
14.0
12.8
102.25
56.4
TS2
–
180
a Shown in Figs 3 and 4.
b Data taken from the numerical integration of the probability density of population curves shown in Figs 1(b,d) and 2(b,d).
Figure 5. Experimental (a) and simulated (b) phosphorus-coupled 1H NMR spectra of bis(2-phenethyl)vinylphosphine sulfide (5) in CDCl3 (161.98 MHz).
All 31P–1H spin–spin coupling constants measured in 4–6
and 10 and calculated at different levels of theory in the related
model compounds 11–14, are compiled in Table 2. First of all, it
should be noted that generally, rather good results are obtained
at all levels of theory, with SOPPA and SOPPA(CCSD) performing
noticeably better than DFT-B3LYP. It is noteworthy that the more
time-consuming SOPPA(CCSD) method shows no appreciable
improvement as compared to SOPPA. Especially, very good results
are obtained at the SOPPA level when using aug-cc-pVTZ-J basis
set of Sauer et al.[20] Comparing basis set performance, it also
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S. V. Fedorov et al.
Table 2. 31P–1H Spin–spin coupling constants of dimethylvinylphosphine (11) and dimethylvinylphosphine chalcogenides (12–14) calculated at
different levels of theorya
Basis set
spin–spin
coupling
Cmpd
constant b
Method
cc-pCVDZ
cc-pVDZ-su2
cc-pVTZ-su2
aug-cc-pVTZ-J
Experiment
11
2J(P,HX)
DFT-B3LYP
SOPPA
7.3
2.0
11.7
5.0
11.9
5.1
4.0
5.2
5.8c
SOPPA(CCSD)
DFT-B3LYP
SOPPA
2.2
5.2
5.3
5.2
3J(P,HA)
3J(P,HB)
2J(P,HX)
3J(P,HA)
3J(P,HB)
2J(P,HX)
3J(P,HA)
3J(P,HB)
2J(P,HX)
3J(P,HA)
3J(P,HB)
24.6
26.4
24.8
11.0
12.8
12.1
21.7
13.7
14.3
31.3
33.2
31.0
17.6
19.5
17.9
21.5
12.9
13.3
37.1
38.8
36.2
21.0
23.0
21.2
24.1
14.2
14.7
40.0
41.4
38.6
23.2
24.7
22.8
28.4
28.8
27.1
13.2
14.4
13.6
32.2
20.3
20.9
35.8
35.7
33.4
21.3
20.0
20.3
30.2
17.9
18.3
43.0
42.4
39.6
25.5
25.7
23.8
33.7
19.4
19.9
46.4
45.2
42.3
28.1
27.7
25.6
29.2
29.1
27.4
13.8
14.6
13.8
33.6
21.6
22.1
36.2
35.4
33.2
21.7
21.6
20.1
30.8
14.4
18.7
43.5
44.0
39.3
25.7
27.7
23.3
33.2
16.9
17.2
46.7
47.2
43.6
28.1
30.0
27.6
29.9
29.7
28.0
14.3
15.0
14.2
35.8
23.7
24.0
37.0
36.3
33.9
22.2
22.2
20.6
32.3
19.9
20.1
44.5
43.1
40.2
26.4
25.8
23.9
33.6
17.7
17.9
47.6
48.2
44.5
28.5
30.6
28.1
30.4c
13.1c
28.0d
37.9d
20.8d
26.8e
44.0e
24.4e
24.6f
45.4f
25.2f
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
12
13
14
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
DFT-B3LYP
SOPPA
SOPPA(CCSD)
a All couplings in Hz.
b Conformationally averaged as described in the text.
c Measured in cmpd. 10.
d Measured in cmpd. 4.
e Measured in cmpd. 5.
f Measured in cmpd. 6.
becomes apparent that double- as well as triple-zeta sets with
decontracted s-functions, cc-pVXZ-su2 (X = D, T), show almost
equally good results while double-zeta basis set augmented with
inner correlation core s-functions, cc-pCVDZ, performs noticeably
worse. It is thus SOPPA/aug-cc-pVTZ-J level which we will use
further on in the calculations of 31P–1H coupling constants.
Interestingly, vicinal 31P–1H spin–spin coupling constants,
3J(P,H), are more gratifying objects for theoretical calculations as
compared to geminal couplings, 2J(P,H). For the latter, in the series
of vinylphosphine chalcogenides 12–14, DFT-B3LYP method
unacceptably overestimates experimental 2J(P,H) values by ca
6–9 HzwhileSOPPAandSOPPA(CCSD)essentiallyunderestimates
2
experimental J(P,H) couplings by ca 4–6 Hz. At the same time,
both vicinal couplings, 3J(P,HA) and 3J(P,HB), are reproduced at all
levels of theory with a good accuracy of ca 2 Hz.
It is noteworthy that a good agreement of calculated 31P–1H
spin–spin coupling constants in 11–14 with experiment is
achieved only provided the conformational averaging of the for-
mer is applied. In fact, theoretical value of each J(P,H) coupling
given in Table 2 is obtained by its conformational averaging be-
tween the true-minimum conformers of 11–14 (i.e. calculated in
both true-minimum conformers of each compound and averaged
c
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Conformational analysis of vinylphosphine and vinylphosphine chalcogenides
Table 3. 31P–1H Spin–spin coupling constants in different conformers of dimethylvinylphosphine(11) and dimethylvinylphosphine chalcogenides
(12–14) calculated at the SOPPA/aug-cc-pVTZ-J level of theory a)
Calculated
spin–spin
coupling
constant
Cmpd
Conformer b
JDSO
JPSO
JSD
JFC
J
Experiment
5.8c
11
2J(P,HX)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
planar s-cis (A)
orthogonal (B)
−0.3
−0.3
−0.6
−0.6
0.1
−0.7
−0.8
0.0
−0.3
0.0
−9.7
31.5
40.3
14.4
19.9
8.4
−11.0
30.4
39.6
14.2
19.5
8.1
3J(P,HA)
3J(P,HB)
2J(P,HX)
3J(P,HA)
3J(P,HB)
2J(P,HX)
3J(P,HA)
3J(P,HB)
2J(P,HX)
3J(P,HA)
3J(P,HB)
−0.1
0.2
30.4c
13.1c
28.0d
37.9d
20.8d
26.8 e
44.0 e
24.4 e
24.6 f
45.4 f
25.2 f
0.1
−0.5
−0.0
−0.3
−0.4
0.3
0.1
−0.1
−0.1
−0.1
−0.5
−0.5
0.2
−0.2
−0.0
−0.0
−0.1
−0.0
−0.1
−0.1
−0.1
−0.0
−0.0
0.0
12
13
14
25.8
8.5
25.3
8.0
36.3
39.6
22.5
20.8
21.6
14.4
43.6
41.5
26.5
22.5
18.9
13.5
48.8
46.0
31.0
26.3
36.0
39.4
22.3
20.8
21.0
13.9
43.4
41.4
26.4
22.5
18.3
13.0
48.5
45.7
31.1
26.5
0.4
−0.3
−0.0
−0.4
−0.5
0.3
0.1
−0.1
−0.0
−0.5
−0.5
0.2
0.4
−0.2
−0.0
−0.5
−0.5
0.2
−0.1
−0.1
−0.2
−0.1
−0.1
−0.1
−0.1
−0.1
0.1
0.1
0.1
−0.4
−0.4
0.4
0.2
−0.2
−0.0
0.3
a All couplings and coupling contributions in Hz.
b Optimized at the MP2/6-311G∗∗ level, see Figs 3 and 4.
c Measured in cmpd. 10.
d Measured in cmpd. 4.
e Measured in cmpd. 5.
f Measured in cmpd. 6.
according to their populations subject to their degeneracies).
Given in Table 3 are the 31P–1H spin–spin coupling constants
calculated in different conformers of 11–14. According to these
data, it appears that conformational averaging is a crucial point in
theoreticalcalculationsofJ(P,H)invinylphosphinesandvinylphos-
phine chalcogenides. Indeed, all geminal couplings, 2J(P,HX), differ
dramatically in planar s-cis and orthogonal conformers of 11–14,
and the same is true for both vicinal couplings, 3J(P,HA) and
3J(P,HB), in vinylphosphine 11, see Table 3. For example, 2J(P,HX)
is ca −11 Hz in planar s-cis conformer of 11, while it is more than
+30 Hz in its orthogonal conformation. On the other hand, the
valuesof3J(P,HA)inthetitleconformersof 11totalstoaccordingly,
ca +40 and +14 Hz. Needless to recall that this remarkable stere-
ospecificity of all studied J(P,H) is provided by their Fermi contact
contributions, as it follows from the data presented in Table 3.
Additional calculations were performed to evaluate the
effect of the replacement of two phenethyl substitutens
by the methyl groups on calculated spin–spin couplings.
For this purpose, planar s-cis and orthogonal conformers
of bis(2-phenethylvinyl)phosphine (10) were localized at the
MP2/6-311G∗∗ level, and all three conformationally averaged
31P–1H spin–spin coupling constants were calculated at the high-
est possible level B3LYP/6-31G* (restricted by molecular size and
software limitations) to be compared with the corresponding
data for the model dimethylvinylphosphine (11) obtained under
equivalent conditions. It appeared that the replacement of two
phenethyl substitutens by the methyl groups on going from 10
to 11 provides no noticeable effect on the calculated 31P–1H
spin–spin coupling constants (varying from 0.5 to 1 Hz), either
on their total values or their individual contributions, which jus-
tifies the usage of compounds 11–14 as molecular models for,
accordingly, 10 and 4–6.
This striking evidence of apparent very strong conformational
behavior of J(P,H) in vinylphosphines and vinylphosphine chalco-
genides encouraged us to study their dihedral angle dependences
in the series of model set of 11–14, and the most interesting
results are depicted in Figs 6–8.
The most remarkable dihedral angle dependences are found
for all three 31P–1H spin–spin couplings, 2J(P,HX), 3J(P,HA) and
3J(P,HB), in vinylphosphine 11 (Fig. 6) which is not surprising
and should be accounted for the well known LP effect upon
spin–spin coupling constants of different types reviewed by Gil
and Philipsborn.[22] Indeed, when going from s-cis (φ = 0◦) to
s-trans (φ = 180◦) conformation of 11 (notation of φ in 11 is given
in Fig. 1), one should expect the increase of 2J(P,HX) and decrease
of 3J(P,HA) and 3J(P,HB) – that is what we expected and what we
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Copyright ꢀ 2009 John Wiley & Sons, Ltd.
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S. V. Fedorov et al.
Figure 6. Dihedral angle dependences of 2J(P,H) and 3J(P,H) in dimethylvinylphosphine (11) calculated at the SOPPA level. Values of φ = 0◦ are assigned
to the s-cis arrangements of the vinyl group and the phosphorus lone pair.
see in Fig. 6. For example, 2J(P,HX) increases by more than 60 Hz Concluding Remarks
(!) when going from s-cis to s-trans conformation which is due to
thehyperconjugativenσ -σ∗CH interactioninvolvingphosphorusLP
A detailed study of the conformational behavior of geminal
and vicinal 31P–1H spin–spin coupling constants in the series
andantibondingorbitaloftheC-HX bond(theso-calledPerlineffect
of vinylphosphine and vinylphosphine chalcogenides has been
performed at different levels of theory in comparison with
experiment. The most interesting result of this communication
is that 31P–1H couplings provide very marked stereospecificity
or a particular case of anomeric effect[23]) in s-cis conformation
resulting in the marked decrease of 2J(P,HX). On the other hand,
spatial proximity of phosphorus LP and one of the coupled nuclei,
HX, in the s-trans conformation results in the marked increase
with respect to the orientational phosphorus LP effect and
2
of J(P,HX). It is the interplay of these two effects which results
that of the P=X double bonds (X = O, S, Se) which implies
in the dramatic difference of more than 60 Hz of this coupling
in s-cis and s-trans conformations of 11. The same remarkable
stereospecificity of 2J(Se,H) and 3J(Se,H) involving protons of the
a great care to be taken in the stereochemical studies of
unsaturated phosphines and phosphine chalcogenides based
on 31P–1H spin–spin coupling constants. To avoid misleading
conclusions and erroneous spectral assignments based on 2J(P,H)
vinyl group attached to selenium atom due to the orientational
LP effect of selenium was documented very recently9 for divinyl
selenide.
and 3J(P,H), the trends of their stereochemical behavior reported
herewith should first be taken into account before any of their
conformational applications.
Turning to vinylphosphine chalcogenides 12–14, it should be
noted that 2J(P,HX) increases by ca 4 Hz in 12 while it decreases by
ca9 Hzin13andbyca5 Hzin14whengoingfroms-cis(φ =0◦)tos-
trans (φ = 180◦) conformations of 12–14 (notations of φ in 12–14
are given in Figs 1 and 2), see Fig.7. Conformational effects on
vicinal couplings,3J(P,HA) and 3J(P,HB), are much less pronounced
in this series (within the range of ꢀJ ≈ 2 Hz), except for 3J(P,HB)
in vinylphosphine oxide 12, the latter markedly decreasing by
ca 20 Hz with φ increasing from 0 to 180◦ (Fig. 8). We will not
address these effects in detail which are apparently due to the
particular hyperconjugative interactions involving the P=X double
bonds (X = O, S, Se) which are above the scope of the present
communication and which deserve the special detailed studies
like those done in several recent publications by Contreras and
colleagues.[24]
Experimental
NMR measurements
1H, 13C, and 31P NMR spectra were recorded on a Bruker DPX
400 MHz spectrometer (1H, 400.13 MHz; 13C, 100.62 MHz; 31P,
161.98 MHz) in a 5 mm broadband probe at 25 ◦C in CDCl3 with
HMDS (hexamethyldisiloxane) as an internal standard. 31P–1H
coupling constants were measured from the phosphorus-coupled
1H NMR spectra using the spectral settings as follows: 90◦ pulse
length, 7 µs; spectral width, 4 kHz; acquisition time, 5 s; relaxation
delay, 10 s; spectral resolution 0.05 Hz/pt; accumulation time,
10 min.
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Magn. Reson. Chem. 2009, 47, 288–299

Conformational analysis of vinylphosphine and vinylphosphine chalcogenides
Figure 7. Dihedral angle dependences of 2J(P,H) in dimethylvinylphosphine chalcogenides (12-14) calculated at the SOPPA level. Values of φ = 0◦ are
assigned to the s-cis arrangements of the vinyl group and the P=X bonds (X = O, S, Se).
Computational details
1009, 1141 [δ, CH(Ph)], 1167 (ν, P=O), 1213 [δ, CH(Ph)], 1390 (δ,
=CH2), 1453 (δ, CH2), 1497, 1583, [ν, C=C(Ph)], 1603 [ν, C=C (C=C),
C=C(Ph)], 2853, 2863, 2922, 2997 (ν, CH), 3001, 3027, 3062, 3085,
3106 [ν, =CH2, =CH (C=C), C=C(Ph)]; 1H chemical shifts, CDCl3 (δ,
ppm): 1.99–2.11 (m, 4H, CH2 P=O); 2.86–2.94 (m, 4H, CH2Ph); 6.14
(m, 1H, H(X)); 6.25 (m, 1H, H(A)); 6.38 (m, 1H, H(B)); 7.18–7.28 (m,
10H, Ph); 2JH(A)H(B) = 1.4 Hz; 3JH(A)H(X) = 12.6 Hz; 3JH(B)H(X) = 18.5 Hz;
2JPH(X) = 28.0 Hz); 3JPH(A) = 37.9 Hz; 3JPH(B) = 20.8 Hz; 13C chemical
shifts, CDCl3, (δ, ppm): 27.60 M (CPh, 2JPC = 3.0 Hz), 31.60 (CP,1JPC
= 67.0 Hz), 126.50 (Cp), 128.10 (Co), 128.70 (Cm), 130.70 (=CH2, 1JPC
= 86.8 Hz), 135.20 (=CH), 141.0 (Cipso, 3JPC = 14.1 Hz); 31P chemical
shifts, CDCl3, (δ, ppm): 36.0. Calc. for C18H21OP (%): C, 76.04; H,
7.44; P, 10.89. Found (%): C, 75.35; H, 7.24; P, 9.93.
All geometry optimizations and calculations of the potential
energy curves of 11–14 were performed with the GAMESS
code[25] at the MP2 perturbation level using the 6-311G∗∗ basis
set of Pople and coworkers[26] without symmetry constraints, i.e.
assuming the C1 symmetry point group. Calculations of spin–spin
coupling constants have been carried out taking into account
all four nonrelativistic coupling contributions with the DALTON
package[27] at the DFT-B3LYP, SOPPA, and SOPPA(CCSD) levels
with different basis sets discussed in the text using the stationary
equilibrium MP2/6-311G∗∗ geometries.
Bis(2-phenethyl)vinylphosphine sulfide (5). Light-yellow oil; IR
(cm−1): 472, 495 (δ, CPC), 543 (ν, P=S), 698 [δ, CH(Ph)], 749 (ν,
P-C), 767 [δ, CH(Ph)], 831, 842 (ω, =CH2); 946, 980 (τ, =CH), 1012,
1134, 1181, 1211 [δ, CH(Ph)], 1384 (δ, =CH2), 1453 (δ, =CH2), 1496,
1584, 1602 [ν, C=C(Ph)]; 2862, 2892, 2929 (ν, CH), 3000, 3026,
3061, 3084, 3103 [ν, =CH(Ph)]; 1H chemical shifts, CDCl3 (δ, ppm):
2.13–2.28 (m, 4H, CH2P); 2.79–3.06 (m, 4H, CH2Ph); 6.22 (m, 1H,
H(X)); 6.25 (m, 1H, H(A)); 6.47 (m, 1H, H(B)); 7.20–7.33 (m, 10H, Ph);
Synthesis
Synthesis of vinylphosphine chalcogenides 4–6. Suspension of
ethyl vinyl sulfoxide, phosphine chalcogenides 1–3 (molar ratio
∼ 1 : 1) and KOH in dioxane was heated at 40–70 ◦C. The resulted
suspension was filtrated, dioxane was removed from the filtrate
to give phosphine chalcogenides 4–6 (details of the experiments
will be published later).
Bis(2-phenethyl)vinylphosphine oxide (4). Colourless crystals, mp
92 ◦C (acetone); IR (KBr, cm−1): 465, 492 (δ, CPC), 698 [δ, CH(Ph)],
756 (ν, P-C), 781 [δ, CH(Ph)], 834 (ω, =CH2), 942, 965 (τ, =CH),
3
3
2
2JH(A)H(B) = 1.6 Hz, JH(A)H(X) = 11.5 Hz, JH(B)H(X) = 17.6 Hz. JPH(X)
= 26.8 Hz, 3JPH(A) = 44.0 Hz, 3JPH(B) = 24.4 Hz; 13C chemical shifts,
2
CDCl3, (δ, ppm): 28.30 (d, CPh, JPC 2.1 Hz), 34.20 (d, CP,1JPC
=
c
Magn. Reson. Chem. 2009, 47, 288–299
Copyright ꢀ 2009 John Wiley & Sons, Ltd.
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S. V. Fedorov et al.
Figure 8. Dihedral angle dependence of 3J(P,HB) in dimethylvinylphosphine oxide (12) calculated at the SOPPA level. Value of φ = 0◦ is assigned to the
s-cis arrangement of the vinyl group and the P=O bond.
52.8 Hz), 126.50 (Cp), 128.30 (Co), 128.70 (Cm), 130.10 (d, CH2 =,
1JPC = 69.9 Hz), 135.20 (d, =CH, 2JPC = 1.1 Hz), 140.8 (d, Cipso, 3JPC
= 15.1 Hz); 31P chemical shifts, CDCl3, (δ, ppm): 42.52. Calc. for
C18H21PS (%): C, 71.97; H, 7.05; P, 10.31, S, 10.67. Found (%): C,
71.82; H, 6.99; P, 10.91, S, 10.51.
(d, CP,1JPC = 13.2 Hz), 32.56 M (d, CPh, 2JPC = 14.0 Hz), 126.02 (Cp),
127.80 (Co), 128.10 (d, =CH2, 2JPC = 19.6 Hz), 128.40 (Cm), 140.0 (d,
1
3
=CH, JPC = 19.6 Hz), 143.11 (Cipso, JPC = 10.0 Hz); 31P chemical
shifts, CDCl3, (δ, ppm): - 26.80. Calc. for C18H21P (%): C, 80.57; H,
7.89; P, 11.54. Found (%): C, 80.82; H, 7.99; P, 11.21.
Bis(2-phenethylvinyl)phosphine selenide (6). Light-yellow oil; IR
(cm−1): 448 (ν, P=Se), shl 465, 493 (δ, CPC), 698 [δ, CH(Ph)],
753 (ν, P-C), 769 (δ, CH of phenyl rings), 839, 860 (ω, =CH2), 945,
978 (τ, =CH), 1013, 1134, 1210 [δ, CH(Ph)], 1382 (δ, =CH2), 1453
(δ, CH2), 1496, 1583 [ν, C=C(Ph)], 1602 [ν, C=C (C=C), C=C(Ph)],
2863, 2903, 2926, 2946 (ν, CH), 3001, 3026, 3061, 3084, 3106 [ν,
=CH2, =CH (C=C), C=C(Ph)]; 1H chemical shifts, CDCl3 (δ, ppm):
2.22–2.31 (m, 4H, CH2P); 2.71–3.06 (m, 4H, CH2Ph); 6.21 (m, 1H,
H(X)); 6.25 (m, 1H, H(A)); 6.47 (m, 1H, H(B)); 7.17–7.26 (m 10H, Ph);
Acknowledgements
Financial support from the Russian Foundation for Basic Research
(Grant No. 08-03-00021) is acknowledged.
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