Spectral assignment of phenanthrene derivatives based on 6H-dibenzo[C,E][1,2] oxaphosphinine 6-Oxide by NMR and quantum chemical calculations

Article abstract of DOI:10.1080/10426507.2011.610848

Organophosphorus compounds such as 6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO, 1) and its derivatives are important and versatile compounds for a broad field of applications. However, a thorough spectral assignment is often subordinate to its chemical properties. This article presents and unambiguously attributes the ¹H and ¹³C NMR spectra of DOPO (1), selected products yielded from the Atherton-Todd reaction (2-4), DOPO-HQ (5) as well as sulfur derivatives (6-7) via a set of 1D- and 2D-NMR experiments. The complex P-C and P-H coupling patterns are discussed and compared with the derivatives possessing different chemical environments around the phosphorus atom. In addition, we compared our results with density functional theory calculations. Even though the prediction of NMR data of organophosphorus compounds via molecular modeling is limited, this study presents a method that yields good results for this class of heterocycles. This knowledge should help to quickly assign NMR spectroscopic data of other DOPO (1) derivatives and can be extrapolated to organophosphorus compounds in general. Supplemental materials are available for this article. Go to the publisher's online edition of Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental resource: NMR Spectra of Compounds 1-7 (Figures S1 - S15). Copyright Taylor and Francis Group, LLC 2012.

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Spectral Assignment of Phenanthrene
Derivatives Based on 6H-Dibenzo[C,E]
[1,2] Oxaphosphinine 6-Oxide by NMR
and Quantum Chemical Calculations
Sebastian Wagner a , Muriel Rakotomalala a , Frederick Chesneau b
Thomas Zevaco a & Manfred Döring a
,
a Institute of Catalysis Research and Technology , Karlsruhe Institute
of Technology , Eggenstein-Leopoldshafen , Germany
b Institute of Applied Physical Chemistry , University of Heidelberg ,
Heidelberg , Germany
Published online: 30 May 2012.
To cite this article: Sebastian Wagner , Muriel Rakotomalala , Frederick Chesneau , Thomas Zevaco
& Manfred Döring (2012) Spectral Assignment of Phenanthrene Derivatives Based on 6H-Dibenzo[C,E]
[1,2] Oxaphosphinine 6-Oxide by NMR and Quantum Chemical Calculations, Phosphorus, Sulfur, and
Silicon and the Related Elements, 187:7, 781-798, DOI: 10.1080/10426507.2011.610848
To link to this article: http://dx.doi.org/10.1080/10426507.2011.610848
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Phosphorus, Sulfur, and Silicon, 187:781–798, 2012
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2011.610848
SPECTRAL ASSIGNMENT OF PHENANTHRENE
DERIVATIVES BASED ON 6H-DIBENZO[C,E][1,2]
OXAPHOSPHININE 6-OXIDE BY NMR AND QUANTUM
CHEMICAL CALCULATIONS
Sebastian Wagner,1 Muriel Rakotomalala,1
Frederick Chesneau,2 Thomas Zevaco,1 and Manfred Do¨ring1
1Institute of Catalysis Research and Technology, Karlsruhe Institute of Technology,
Eggenstein-Leopoldshafen, Germany
2Institute of Applied Physical Chemistry, University of Heidelberg,
Heidelberg, Germany
GRAPHICAL ABSTRACT
Abstract Organophosphorus compounds such as 6H-dibenzo[c,e][1,2]oxaphosphinine 6-
oxide (DOPO, 1) and its derivatives are important and versatile compounds for a broad field
Received 15 June 2011; accepted 1 August 2011.
DOPO (1) was kindly provided by Schill and Seilacher. The authors would also like to thank Mr. Zwick for
measuring HR-MS, Ms. Schmelcher and Ms. Ko¨lmel for elemental analysis, and Dr. Ingmar Held from Schill and
Seilacher.
Address correspondence to Sebastian Wagner, Institute of Catalysis Research and Technology, Karlsruhe
Institute of Technology, Hermann-von-Helmholtz Platz 1, 76344 Eggenstein-Leopoldshafen, Germany. E-mail:
Sebastian.wagner@kit.edu
781

782
S. WAGNER ET AL.
of applications. However, a thorough spectral assignment is often subordinate to its chemical
properties. This article presents and unambiguously attributes the 1H and 13C NMR spectra of
DOPO (1), selected products yielded from the Atherton–Todd reaction (2–4), DOPO-HQ (5)
as well as sulfur derivatives (6–7) via a set of 1D- and 2D-NMR experiments. The complex
P-C and P-H coupling patterns are discussed and compared with the derivatives possessing
different chemical environments around the phosphorus atom. In addition, we compared our
results with density functional theory calculations. Even though the prediction of NMR data of
organophosphorus compounds via molecular modeling is limited, this study presents a method
that yields good results for this class of heterocycles. This knowledge should help to quickly
assign NMR spectroscopic data of other DOPO (1) derivatives and can be extrapolated to
organophosphorus compounds in general.
Supplemental materials are available for this article. Go to the publisher’s online edition of
Phosphorus, Sulfur, and Silicon and the Related Elements for the following free supplemental
resource: NMR Spectra of Compounds 1-7 (Figures S1 - S15).
Keywords NMR; DFT calculations; organophosphorus; heterocycles; Atherton–Todd reaction
INTRODUCTION
For several decades, organophosphorus molecules have been the subject of both
academic and industrial research.1–3 A wide range of applications have been reported in
different areas of chemistry such as coordination chemistry, material science, homoge-
neous catalysis, development of biologically active compounds or pesticides, and additives
for polymers such as lubricants or antioxidants.4–10 There has recently been a growing
interest from the flame retardant community regarding phosphorus-containing molecules
as environmentally friendly alternatives to the existing, and often harmful, halogenated
systems.11–13 Among the broad range of documented phosphorus-based flame retardants,
6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO, 1, cf. Figure 1) and its derivatives
were found to exhibit outstanding performance as flame retardants in various polymers
such as polyesters, epoxies, and styrenics.14,15
In particular, epoxy resins, used for printed wiring boards, are rendered flame retar-
dant by chemically linking DOPO (1) to the epoxy backbone (fusion process).15 Despite
the well-documented chemistry of DOPO (1) and its derivatives, the number of reports
dealing with the detailed characterizations of these compounds is limited. Hence, the use
of 1D- and 2D-NMR spectroscopic methods is still of interest.16–18 Since the 1970s, a wide
Figure 1 6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (DOPO) (Color figure available online).

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
783
range of phosphorus compounds were characterized by NMR spectroscopy; however, in
recent decades, industrially relevant phosphorus compounds such as DOPO (1) were not
the subject of thorough spectroscopic investigations.19 The present article attempts to fill
this gap by comprehensively characterizing DOPO (1) via different NMR spectroscopy
experiments. The attribution of the signals was compared to and supported by density func-
tional theory (DFT) calculations using the individual gauge for localized orbitals (IGLO)
method.20,21 The attribution of NMR signals in organic molecules displaying conjugated
and/or constrained ring systems is challenging. Over the last decade, significant effort has
been invested in the understanding of NMR spectra via molecular modeling.22 The calcu-
lation of nuclear shielding constants and spin-spin couplings requires optimized methods
and basis sets.23 Procedures involving localized orbital models such as LORG (localized
orbital, local origin), IGLO, and GIAO (gauge inclusive atomic orbital), and the more mod-
ern CSGT method (continuous set of gauge transformations method) have been reported in
the literature.24–26
In order to increase our understanding of the attributions and long-range couplings
found in the DOPO (1) spectra, this study was extended to a range of derivatives generated
from the Atherton–Todd reaction of DOPO (1) with resorcinol, phenol, and isopropanol.
Hence, compounds 2, 3, and 4 were synthesized (Scheme 1). Even though those molecules
were reported in the patent literature, their synthesis was not described in all cases. Hence,
we introduce a new synthetic pathway starting from the commercially available DOPO
(1) molecule.27–29 The Atherton–Todd reaction is a well-known and easily applicable
organophosphorus reaction.30–32 Atherton and Todd30 originally reported the reaction as
a very effective tool to yield phosphoramidates. However, the reaction is described to
be poor when alcohols are used as nucleophiles. Recent literature indicates that success-
ful application of alcohols in the Atherton–Todd reaction is strongly dependent on the
phosphorus species.30,32 DOPO (1) in general was found to react easily with all kinds of
nucleophiles under Atherton–Todd conditions. The characterization of these comparable
molecules should support the proposed attribution and coupling pattern of the DOPO (1)
base structure.
Scheme 1
Similarly, the known reaction product of DOPO (1) with hydroquinone (DOPO-HQ,
5) was included in this study in order to correlate our results with the ones reported by
Wang and co-workers.33,34 In addition, we included two sulfur-containing DOPO derivatives
recently reported by Rakotomalala and co-workers: DOPS (6) and its nucleophilic addition
product to hydroquinone DOPS-HQ (7) to investigate the influence of the heteroatom

784
S. WAGNER ET AL.
Figure 2 DOPO-HQ (5) and the sulfur derivatives DOPS (6) and DOPS-HQ (7).
present in the bridging dibenzooxaphosphinine ring on both chemical shifts and scalar
couplings (Figure 2). 35
It is known that an NMR-active nucleus, with a medium sensitivity, like phosphorus is
able to generate coupling patterns with proton and carbon atoms over long distances. Up to 5J
couplings can be observed with a proper NMR resolution. P-H and P-C long-range couplings
have been reported in the literature in systems based on phosphoramidates.36 The attribution
of the signals is complicated since the scalar coupling does not necessarily decrease with
increasing distance from the phosphorus atom. The general structure of DOPO (1) and its
derivatives exhibits an almost planar geometry with an extended conjugated system that
favors the occurrence of long-range couplings.37,38 Several models have been proposed
to understand long-range spin-spin couplings in organophosphorus systems, ranging from
hyperconjugative mechanisms to angle-dependant models involving P-C bonds and planes
of the Pi-electron systems.39,40 Thus, it was interesting to examine the P-H and P-C long-
range couplings observed for DOPO (1) and its derivatives and compare them with the
existing literature.
RESULTS AND DISCUSSION
1
As predicted, the deceptively simple H NMR spectrum of DOPO (1) shows the
presence of eight aromatic protons. The well-resolved signals in the aromatic region are
indicative of a rigid ring system and coherent with the parent phenanthrene structure.41,42
In addition, the doublet at 8.04 ppm (1JP-H = 604 Hz) is characteristic for the P-H bond. In
the 1H NMR spectrum, H2, H5, H8, and H11 are all expected to be doublets while H3, H4,
H9, and H10 are expected to be doublets of doublets, which might appear in simple cases
as triplets. However, in addition to two large doublets (7.84 and 7.23 ppm), a doublet of
doublets (7.89 ppm) and two doublets of triplets (7.66 and 7.47 ppm) are observed.
The overlapping multiplets at lower field rendered the assignment cumbersome.
Hence, the use of high-resolution 2D-NMR methods provided valuable complementary
information for the assignment of the 1H-NMR spectrum of DOPO (1).
As seen in Figure 1, DOPO (1) has two electronically distinct ring systems, i.e., two
independent spin systems (H2-H5 and H8-H11). The standard COSY spectrum of DOPO
(1) provided the first handle toward an assignment of the 1H NMR data. Indeed, as seen in
Figure 3, a correlation is observed between Hp and H11. The gCOSY spectrum emphasizes
the correlation between H11 and H10 (Figure 4). As seen in Table 1, the coupling constant
observed coincides with two neighboring protons on an ortho-substituted benzene ring

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
785
Figure 3 H,H-COSY NMR spectrum of 1 (DOPO). The Hp coupling with H2 and H11 is highlighted (Color
figure available online).
with an electron withdrawing substituent. The ortho substitution is further confirmed as the
triplet of doublets at 7.66 ppm (H10) is coupled to the triplet of doublets at 7.47 ppm (H9).
The latter proton couples with the doublet of doublet at 7.81 ppm assigned to H8. The large
coupling constants are indicative of a coupling with the phosphorus atom. In accordance
with the electron withdrawing capability of the P = O moiety, the phosphorylated ring is
Table 1 1H NMR data of compound 1 (DOPO) in CDCl3
Experimental
δ (ppm)
J 1Hx-1Hy 3J (Hz)
J
31P-1H (Hz)
Hp
8.04
—
8.0
8.3
8.0
7.6
7.6
7.5
8.3
8.0
—
604 (1J)
—
H2
H3
H4
H5
H8
H9
H10
H11
7.23 (d)
7.33 (t)
7.21 (t)
7.84 (d)
7.81 (dd)
7.47 (td)
7.66 (td)
7.89 (d)
3JH2-H3
3JH3-H2
3JH4-H3
3JH5-H4
3JH8-H9
3JH9-H8
3JH10-H9
3JH11-H10
1.0 (5J)
—
—
16.5 (4J)
3.5 (5J)
1.0 (4J)
5.2 (3J)

786
S. WAGNER ET AL.
Figure 4 The gCOSY NMR spectrum of DOPO (1) (Color figure available online).
more downfield shifted (deshielded) than the oxygenated one. The standard COSY spectrum
shown in Figure 3 emphasizes the long-range correlation between HP and the peak observed
at δ = 7.23 ppm (d, J = 8.00 Hz). This provided a handle toward the assignment of the
second ring system. The multiplicity indicates that the proton is ortho with respect to one of
the two substituents on the phenyl ring (H2 or H5). However, a second doublet is observed
at δ = 7.84 ppm. The relative similarity in the electronic environment between H2 and
H5 allowed the assignment of the doublet more deshielded to H5. Hence, this, and more
importantly the correlation with Hp, led to the assigned of the second doublet to H2. This
is coherent with the difference in the electron donating ability between phosphorus and
oxygen. In DOPO (1), the high oxidation state of the phosphorus atom leads to a more
deshielded H11 compared to H2. The gCOSY spectrum showed a correlation between H2
and the triplet at δ = 7.33 ppm, which was assigned to H3. Consequently, H3 couples to a
second triplet at 7.21 ppm (t, J = 8.0 Hz) associated with H4. A correlation between H4 and
H5 is also observed in the H,H-COSY spectrum. Hence, all protons on the phenanthrene
ring were assigned for DOPO (1). The observed NMR data are presented in Table 1.
The 13C NMR of molecule 1 displays 12 signals, including eight methine carbons and
four quaternary carbons. The correlations observed in the HMBC spectrum between HP and
two of the quaternary carbons enabled the assignment of C1 and C12 (Figure 5). Hence,
the remaining quaternary carbons were assigned as C6 and C7. In addition, the correlations

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
787
Figure 5 The HMBC spectrum of DOPO (1) showed Hp couplings with C1, C7, and C11 (Color figure available
online).
observed in the HMQC spectrum of DOPO (1) enabled the unambiguous attribution of
signals C2, C3, C4, C5, C8, C9, C10, and C11 (Figure 6).
The exact attribution of carbons C6 and C7 of the DOPO (1) structure is not straight-
forward and requires further proof. As seen in Figure 4, the signals attributed to the
phosphorus-substituted ring systems are shifted more downfield than the signals associated
with the oxygen-substituted ring system. Hence, of the remaining two unassigned quater-
nary carbons, the lower field signal (δ = 135.9 ppm, JP-C = 6.5 Hz) was attributed to C7
while the higher field signal (δ = 122.1 ppm, JP-C = 12.3 Hz) was assigned to C6. Support-
ing this assignment, C7 was the only carbon to be correlated to HP in the long range HMBC
spectrum of DOPO (1) (Figure 5). In addition, the HMBC spectrum reveals correlations
between C7 and the protons H8, H9, H10, and H11 of the same ring system. From the
other ring system, only a coupling for C7 with H5 was observed. Complementary to that
observation, carbon C6 demonstrates couplings with all protons from its ring system (H2,
H3, H4, and H5) and only with proton H8 from the opposite ring. Hence, we successfully
assigned all carbon atoms. The 13C NMR data of DOPO (1) are presented in Table 2.
MOLECULAR MODELING AND CHEMICAL SHIFTS CALCULATIONS
In order to support our results and propose some general guidelines for the attribution
1
of NMR signals within such complex systems, the H NMR and 13C NMR spectrum of
DOPO (1) was calculated using suitable DFT methods. Of different approaches, the VWN5
method and the NMR-specific IGLO-III basis set proved to be the most accurate.43 The

788
S. WAGNER ET AL.
Figure 6 The HMQC spectrum of DOPO (1) (Color figure available online).
1
results of our calculations of the H NMR chemical shifts of DOPO (1) in CDCl3 are
presented in Table 3.
The experimental and calculated chemical shifts are in good agreement at all levels
of theory, except for protons H10 and H9, with an average unsigned error of 0.20 ppm for
the B3LYP hybrid functional, 0.09 ppm for the mPW1PW hybrid functional, and 0.07 ppm
for the VWN5 correlation functional (H9 and H10 were removed from error calculation,
0.14 ppm when H9 and H10 were included). These values are in line with the state of
Table 2 13C NMR data of 1 (DOPO)
#
δ (ppm)
J
31P-13C (Hz)
C1
C2
C3
C4
C5
C6
C7
C8
148.2 (d)
120.7 (d)
131.0 (s)
125.3 (s)
125.2 (s)
122.1 (d)
135.9 (d)
130.7 (d)
128.8 (d)
134.2 (d)
124.1 (d)
123.6 (d)
8.4 (2J)
6.3 (3J)
12.2 (3J)
6.5 (2J)
12.7 (3J)
14.3 (4J)
2.4 (3J)
C9
C10
C11
C12
9.7 (2J)
122.1 (1J)

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
789
Table 3 Calculated 1H NMR chemical shifts of the ring protons of 1 (DOPO)
VWN5
Aug-cc-pVDZ
B3LYP
mPW1PW
IGLO-III
#
Expt.
IGLO-III
IGLO-III
Aug-cc-pVDZ
6311-G∗∗
H2
H3
H4
H5
H8
H9
H10
H11
7.23
7.33
7.21
7.84
7.81
7.47
7.66
7.89
7.06
7.46
7.06
7.86
7.76
7.76
7.36
7.86
6.56
7.26
6.56
7.96
8.36
8.06
7.06
7.16
7.21
7.51
7.01
8.01
7.71
7.81
7.31
8.11
7.96
8.96
8.06
9.46
9.86
9.46
8.56
8.96
7.11
8.01
7.01
8.01
7.51
8.21
7.31
8.01
7.11
7.61
7.11
8.01
7.81
7.91
7.41
7.91
Note: The experimental values are given for reference. All values are expressed in ppm.
the art.44 Although the trends are coarsely reproduced, the more popular B3LYP/6311-G∗∗
level of theory fails to predict reasonable chemical shifts with an average unsigned error of
0.20 ppm, more than twice that of our most accurate method (VWN5/IGLO-III). Note that
the double zeta method fails to quantitatively predict the chemical shifts both with VWN5
and B3LYP (average unsigned error: 0.35 and 1 ppm, respectively). Although it is a suitable
method for organic molecules, our results suggest that it is not applicable for phosphorus-
containing molecules such as DOPO (1). As seen in Table 3, the proton peaks for H10 and
H9 are not correctly assigned in our calculations, irrespective of the functional or basis set
used. To resolve this issue, we have calculated the 1H NMR spectrum of phenylphosphinic
acid both in CDCl3 and in the gas phase and compared it with the values reported by Gervais
et al.45 As expected, on the basis of our experimental assignments, the chemical shifts of
protons H10 and H9 are again inverted in these calculations (data not shown).
The chemical shift of the proton attached to the phosphorus was predicted to be 8.46
ppm using the VWN5 functional, 7.91 ppm using the mPW1PW functional (best agreement
with our experiments), and 7.71 ppm using the B3LYP/6311G∗∗ method. In addition to the
1H NMR, the 13C NMR chemical shifts of DOPO (1) were calculated in the same manner
and are summarized in Table 4.
1
Similar to the H NMR calculations, the VWN5/IGLO-III method gave the best
agreement with the experiment with an average unsigned error (C8–C11 excluded) of 1.3
ppm (mPW1PW: 1.6 ppm; B3LYP: 2.5 ppm). All methods used in this study give average
unsigned errors in line with the state of the art.46 However, the chemical shifts of carbons
C8–C11 are wrongly predicted by all the methods used in this study. The error in the
assignment of C9 and C10 can be correlated with that of their respective protons (H9 and
H10, as described above). However, even though their respective protons are correctly
assigned by our calculations, C8 and C11 are not. Our spectroscopic investigations clearly
assign the peak at 130.7 ppm to C8 and that at 124.1 ppm to C11. In addition, our calculations
also confirm some of the key carbons such as C1 and C12, as well as the hard to differentiate
C6 and C7. To the best of our knowledge, our theoretical calculations of 13C NMR chemical
shifts are the first reported for organophosphorus compounds like 1.
Even though the experimental assignments of the 1H and 13C NMR chemical shifts
are largely reproduced by theory, especially for the oxygen-substituted ring, the method
used (IGLO) showed limitations for the assignment of the proton and carbon atoms of the

790
S. WAGNER ET AL.
Table 4 Calculated 13C NMR chemical shifts for the ring carbons of 1 (DOPO)
B3LYP
VWN5
mPW1PW
IGLO-III
#
Expt.
IGLO-III
IGLO-III
6311-G∗∗
C1
C2
C3
C4
C5
C6
C7
C8
148.2
120.7
131
152.2
120.1
131.3
123.9
125.0
124.0
137.9
123.8
134.7
128.5
130.3
126.5
154
152.1
118.3
133.6
123.3
125.9
118.9
136.2
121.5
136.1
126.9
132.1
119.0
151.9
119.4
131.9
123.5
125.6
123.1
138.7
123.3
135.0
127.9
131.9
124.3
119.9
131.2
122.8
124.8
124.4
140.0
122.5
133.6
127.2
132.5
127.1
125.3
125.2
122.1
135.9
130.7
128.8
134.2
124.1
123.6
C9
C10
C11
C12
Note: The experimental values are given for reference. All values are expressed in ppm.
phosphorus-substituted ring. Although IGLO is known to perform worse in the case of sys-
tems with delocalized electrons, repeating the calculations of the proton chemical shifts us-
ing the GIAO method implemented in the GAUSSIAN03 software package (gas phase, data
not shown) did not yield an improvement in the average unsigned error (0.13 vs. 0.07 ppm
for our best method).25,47 Furthermore, a similar assignment for the chemical shifts of pro-
tons H9 and H10 was found. However, the error in the chemical shifts was more systematic
with the latter method. Using the projected augmented-wave approach, Gervais et al. cor-
rectly predicted the relative chemical shifts of H9 and H10 in phenylphosphinic acid.45,48
Therefore, we conclude that both the IGLO and GIAO methods wrongly assign the pro-
tons meta and para to PHOO groups and care should be taken when using these methods
for the calculation of chemical shifts in organophosphorus compounds. Unfortunately, the
complete assignment of the experimental NMR spectra of organophosphorus compounds is
complicated and time-consuming. In contrast, our calculations, using the VWN5/IGLO-III
method, require less than 15 min of computing time on a 2 GHz Core Duo machine with 2
GB of RAM. We expect the computational cost to significantly decrease on more modern
machines. As seen above, the VWN5/IGLO-III method yields reasonable chemical shifts
for DOPO (1) at a low computational cost. Thus, this study serves as a benchmark for
the rapid calculation of NMR spectra of organophosphorus compounds. Furthermore, it
supports and accelerates the cumbersome structure solving process.
SYNTHESIS AND CHARACTERIZATION OF DOPO DERIVATIVES
Since the DOPO (1) attribution was complete, we initiated the synthesis of derivatives
of DOPO (1) via the Atherton–Todd approach and investigated the influence of the chem-
ical environment around the phosphorus on the spectroscopic properties of the resulting
molecules. The reaction products of DOPO with resorcinol (2), phenol (3), and isopropanol
(4) in the presence of triethylamine and carbon tetrachloride were obtained in good yields
(Scheme 1). The in situ formation of the oxychloride intermediate 1a can be observed via
31P NMR (δ 31P = 21.3 ppm). 1a can also be isolated. Other reactive species were reported
or proposed in the literature.49 In addition, novel sulfur-containing DOPO (1) derivatives

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
791
Table 5 1H-NMR data of compound 1 (DOPO) and its derivatives 2–7 in CDCl3
33
#
1
2
3
4
5a
6
7a
7.18 (dd)
H2
H3
H4
H5
H8
H9
7.23 (d)
7.33 (t)
7.21 (t)
7.84 (d)
7.81 (dd) 7.94–7.87 (m)
7.47 (td)
7.13 (tt)
7.32 (m)
7.23 (t)
7.20–7.15 (m)
7.32–7.26 (m)
7.23 (t)
7.14 (d)
7.3 (t)
7.18 (t)
7.25 (d)
7.40 (t)
7.25 (t)
8.18 (t)
7.21 (dd)
7.35 (dt) 7.47–7.36 (m)
7.24 (t)
7.82 (d)
7.24 (dt)
8.11 (d)
7.94–7.87 (m) 7.94–7.88 (m) 7.89–7.84 (m)
7.95 (dd)
7.45 (td)
7.68 (t)
7.9 (dd)
7.43 (td)
7.62 (t)
7.55 (dd) 7.81 (dd) 7.47–7.36 (m)
7.42 (td)
7.68 (t)
7.46 (td)
7.69 (t)
8.20 (t)
7.52 (td) 7.47–7.36 (m)
7.66 (t) 7.63 (dt)
7.94 (dd) 8.12–8.09 (m)
H10 7.66 (td)
H11 7.89 (d)
7.94–7.87 (m) 7.94–7.88 (m) 7.89–7.84 (m)
aMeasured in DMSO-d6. All values are expressed in ppm.
DOPS (6) and DOPS-HQ (7) recently reported by Rakotomalala and co-workers, as well
as DOPO-HQ (5) described by Wang and co-workers were added to this study.33,35 The
1
1H NMR data of DOPO (1) and its derivatives are presented in Table 5. Selected H and
13C NMR spectra for compounds 1–7 are presented in the Supplemental Materials (Figures
S 1–S 15).
The 13C NMR data as well as the phosphorus shifts are shown in Tables 6 and 7,
respectively. It should be noted that DOPO-HQ (5) and DOPS-HQ (7) are insoluble in
chloroform and thus were measured in DMSO-d6. The results are still comparable since
only protons H8 and H11 slightly move to lower as well as higher field, respectively. This
trend was observed for all DOPO (1) derivatives measured in DMSO-d6 (data not shown).
Being a bridged molecule with two DOPO (1) groups, 2 was expected to show the most
complex 1H NMR data, but with the knowledge gained from the DOPO (1) attribution, the
proton and carbon assignment was simplified (Figure 7, DMSO-d6 was chosen due to a
better resolution).
In addition, the attribution of 3 and 4 was successful and all results correlate with the
attribution performed for the parent compound, DOPO (1). Our attribution of 5 correlates
with the literature by Wang et al.32 The DOPO (1) derivative 4 has the advantage that the
isopropanol subunit has proton and carbon NMR signals in the aliphatic region. The HMBC
33
Table 6 13C NMR data of compound 1 (DOPO) and its derivatives 2–7 in CDCl3
#
1
2
3
4
5a
6
7a
C1
C2
C3
C4
C5
C6
C7
C8
148.2 (d)
120.7 (d)
131.0 (s)
125.3 (s)
125.2 (s)
122.1 (d)
135.9 (d)
130.7 (d)
128.8 (d)
134.2 (d)
124.1 (d)
123.6 (d)
150.4 (d)
120.5 (d)
130.8 (s)
125.3 (s)
125.5 (s)
122.6 (d)
137.3 (d)
131.0 (d)
128.6 (d)
134.2 (d)
124.4 (d)
121.3 (d)
148.0 (d)
119.3 (d)
129.6 (s)
124.5 (s)
123.9 (s)
121.4 (d)
136.1 (d)
129.7 (d)
127.3 (d)
132.8 (d)
123.1 (d)
120.0 (d)
150.2 (d)
120.3 (d)
130.5 (s)
124.7 (s)
125.4 (s)
122.9 (d)
137.1 (d)
130.2 (d)
128.4 (d)
133.4 (d)
124.2 (d)
121.0 (d)
150.1 (d)
120.5 (d)
131.2 (s)
124.4 (s)
126.0 (s)
121.8 (d)
135.4 (d)
130.8 (d)
129.0 (d)
133.4 (s)
124.2 (d)
126.2 (d)
149.7 (d)
120.8 (d)
131.1 (s)
124.9 (s)
125.6 (s)
123.6 (d)
135.7 (d)
131.7 (d)
129.0 (d)
134.9 (d)
124.2 (d)
125.4 (d)
147.9 (d)
121.0 (d)
131.1 (s)
125.1 (s)
124.2 (d)
122.5 (d)
134.0 (d)
130.1 (d)
129.1 (d)
132.8 (s)
126.1 (s)
129.2 (d)
C9
C10
C11
C12
aMeasured in DMSO-d6. All values are expressed in ppm.

792
S. WAGNER ET AL.
Table 7 31P NMR data of DOPO (1) and its derivatives 2–7 in CDCl3
33
#
1
2
3
4
5a
6
7a
P
15.7
7.8/7.7
7.95
10.3
19.6
57.1
70.8
aMeasured in DMSO-d6. All values are expressed in ppm.
spectrum of compound 4 supports the general attribution of the neighboring quaternary
carbons C6 and C7. C6 has strong cross peaks with the protons H2, H4, and H5 (same
ring system). In addition, carbon C7 has strong cross peaks with H8, H10, and H11 (same
ring system). These observations are in accordance with the attribution of the DOPO (1)
spectrum. Similar results were found for all derivatives, which indicate that the phosphorus
environment only has a small influence on the 1H and 13C NMR shifts of the phenanthrene
ring.
Interestingly, the 13C NMR data remain almost unaffected. Carbon atom C12, directly
connected to the phosphorus atom, shows only a small shift toward higher fields when the
hydrogen atom in DOPO (1) is replaced by oxygen as a result of the increased electron
density around the phosphorus (compounds 2–4). The replacement of the hydrogen atom
by a sp2 carbon belonging to the electron withdrawing hydroquinone group in 5 and 7
results in a deshielding effect. The sulfur atom in compounds 6 and 7 with its diffused
d-orbitals has an additional deshielding effect on the respective C12 carbon atoms. These
effects are more pronounced in the 31P NMR spectra, with sulfur derivatives 6 and 7 being
Figure 7 H,H-COSY NMR spectrum of 2 (Color figure available online).

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
793
strongly deshielded with respect to the oxygen containing derivatives. Due to the formation
of diastereomers, 2 shows two signals in the 31P NMR spectrum and a set of more complex
multiplets in the 1H NMR spectrum. The 13C NMR spectrum remains almost unaffected.
CONCLUSION
1
The H and 13C NMR spectra of DOPO (1) were successfully assigned using a
combination of 1D- and 2D-NMR techniques. The complete assignment of the protons on
the dibenzooxaphosphinine ring was supported by molecular modeling calculations using
DFT methods. The VWM5 method in combination with the IGLO-III basis set produced
the most accurate predictions for the proton and carbon shifts of DOPO (1) in less than
15 min. Thus, this time-efficient model represents a useful tool for the structure solving
process of organophosphorus molecules in general. The usefulness of this model was further
confirmed as the assignment of 1H and 13C NMR spectra of DOPO (1) could be extrapolated
on a series of substituted derivatives yielded from the Atherton–Todd reaction as well as
thio-derivatives of DOPO (1). The variation of the phosphorus environment had only a
slight impact on the 1H and 13C NMR data of the DOPO (1) derivatives. Since DOPO (1)
and its derivatives are gaining more and more interest from academia and industry, the
knowledge gained from this study can be applied toward the assignment of other polycyclic
phosphorus compounds.
EXPERIMENTAL
General Experimental
Unless stated otherwise, solvents and chemicals were obtained from commer-
cial sources and used without further purification. DOPO (1) was supplied by Schill
and Seilacher. NMR experiments were performed on a Varian Inova-400 spectrometer
(400 MHz), equipped with a 5-mm multinuclear, inverse detection z-gradient probe-head.
The 1H and 13C NMR spectra were measured at 26 ◦C operating at 399.91 and 100.56 MHz,
respectively. All samples were dissolved in 0.5 mL of CDCl3 or DMSO-d6. Chemical shifts
are reported in ppm, and J-coupling constants are expressed in Hz. The calibration was per-
formed using the remaining signal of the nondeuteriated part of the solvent (7.24 ppm) and
the C-D characteristic coupling pattern of the deuteriated solvent in 13C (77.0 ppm). The 2D
spectra, H,C-HSQC, and H,C-HMBC were recorded using standard pulse sequences with
z-gradients, as provided by Varian with the VNMR 6.1C control and processing software.
1
The pulse conditions were as follows: for the H NMR spectra, observation frequency is
399.912 MHz, acquisition time (at) = 3.744 s, number of scans (NS) = 16, number of
dummy scans (SS) = 0, relaxation delay (d1) = 1.0 s, 90◦ pulse width = 6.4 µs, spectral
width (sw) = 4799.0 Hz, no line broadening, and Fourier transform size (np) = 32K; for
the 13C NMR spectra, observation frequency is 100.56 MHz, aq = 1.20 s, ns = 1000, ss =
0, d1 = 1.0 s, 90◦ pulse width = 12.2 µs, sw = 21119.3 Hz, np = 32K, lb = 1.0 Hz;
the H,H-COSY spectra were measured at 399.91 MHz and collected with 1K data points
in F2 with 512 experiments 1 scan; the HSQC spectra were collected with 2k data points
and spectral widths of 4000.0 Hz (F2) and 20,110.0 Hz, respectively; the HMBC spectra
were obtained from 400 experiments 32 scans. The spectral widths used were the same as
the HSQC experiment. The number of dummy scans was set to 32 and the delays were set
to 5 Hz (long range Jnxh parameter) and 140 Hz (short range, J1xh parameter). All 31P

794
S. WAGNER ET AL.
NMR spectra are measured proton decoupled. All 13C NMR spectra were measured proton
decoupled and phosphorus coupled. 1H NMR spectra were measured phosphorus coupled.
Melting points are uncorrected and measured with a Bu¨chi B-545. IR spectra were recorded
with a Varian 660-IR (FT-IR). High-resolution mass spectrometry (HR MS) analyses were
performed on a MicroMass GCT (time of flight [TOF]; electron ionization [EI], 70 eV).
Elemental analysis was performed using a Vario EL III from Elementar Analysensystem
GmbH.
Chemical Shift Calculations
All calculations were performed using the IGLO method implemented in the Orca 2.8
software package.50 The geometry of the molecules was optimized at the RHF/PM3 level
and refined at the B3LYP/6-31G∗ level of theory.51–53 The chemical shifts were calculated
using the VWN5 functional and IGLO-III basis set as well as the more popular B3LYP and
mPW1PW functionals with either the Aug-cc-pVDZ or the 6-311G∗∗ basis sets.54 All were
used as implemented in the Orca 2.8 software package. The calculated values of δ were
extracted using the following equation55:
δcalc = σref − σ + δref
where δref is the experimental chemical shift of the reference molecule, in our case benzene
(1H: δ = 7.36 ppm, σ = 22.7 ppm; 13C: δ = 128.5 ppm, σ = 38.55 ppm), and σref and
σ are the calculated isotropic magnetic shielding values of the reference and molecule of
interest, respectively.55 We evaluated σref to be 22.7 0.1 ppm for 1H and 38.55 0.4 ppm
for 13C in the case of VWN5/IGLO-III. Benzene has been recommended for the calculation
of chemical shifts of sp and sp2 carbons.55 When tetramethylsilane (TMS) was used as a
reference, although the trends were reproduced, the calculated chemical shifts were shifted
downfield by approximately 0.7 ppm. We have found benzene to be a better reference than
TMS for our calculations. For all other methods, similar values of the isotropic magnetic
shielding were obtained. To account for the solvent (CDCl3), the COSMO model was
used.56 The values of 4.81 for the dielectric constant and 1.49 for the refractive index were
applied. The PBE and B3LYP functional and the 6-31G(d) or 6-31+G(d,p) basis sets were
used for the GIAO method implemented in the GAUSSIAN03 software package. Note
1
on the computational cost: whereas the calculation of the H and 13C chemical shifts of
DOPO using mPW1PW and B3LYP hybrid functionals with the IGLO-III basis set lasted
7–8 h on our hardware, VWN5 afforded more accurate chemical shift values for DOPO,
with respect to experiment, in under 12 min. A typical calculation using the less accurate
B3LYP/6311-G∗∗ method lasted approximately 1 h 20 min on the same hardware (Intel
Core Duo 2 GHz, 2 GB RAM).
The synthesis of 6,6ꢁ-(1,3-phenylenebis(oxy))bis(6H-dibenzo[c,e][1,2]oxaphos
phinine 6-oxide) 2 is given as a general example for an Atherton–Todd reaction.
Compounds 3 and 4 are synthesized accordingly: A flame-dried, three-neck flask with a
condenser, addition funnel, thermometer, and stirring bar was charged with 10.0 g (46.2
mmol) DOPO (1), 2.54 g (23.1 mmol) resorcinol, 7.65 g (50.0 mmol) carbon tetrachloride,
and 70 mL of dry chloroform. The additional funnel was charged with 5.05 g (50.0
mmol) triethylamine diluted in 30 mL of dry chloroform. The triethylamine solution was
added to the reaction mixture under vigorous stirring and the mixture was not allowed to

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
795
exceed 10 ◦C by cooling with an ice bath. The reaction progress was monitored by NMR
spectroscopy. After 2 h, the reaction was complete and the mixture was washed three times
with 100 mL brine. The combined organic phases were dried over sodium sulfate and then
filtered over a short pad of alox (basic). The crude product was concentrated in vacuo
◦
yielding 10.76 g (20.1 mmol; 87%) of a white solid. mp: 150–152 C; 31P NMR (101
1
MHz, DMSO-d6): 7.8 (s, 2P), 7.7 ppm (s, 2P); H NMR (400 MHz, CDCl3): 7.94–7.84
(m, 6H, H8/11/5), 7.86 (t, J = 7.5 Hz, 2H, H10), 7.42 (td, J = 7.5 Hz, JP-H = 3.6 Hz, 2H,
H9), 7.34–7.32 (m, 2H, H3), 7.23 (t, J = 7.3 Hz, 2H, H4), 7.13 (tt, J = 8.0 Hz, JP-H = 1.3
Hz, 2H, H2), 7.12 (t, J = 8.0 Hz, 1H, H16), 6.84 (tt, J = 8.1 Hz, JP-H = 1.0, 2H, H14),
6.72 ppm (d, JP-H = 1.3 Hz, 1H, H15); 13C NMR (100 MHz, CDCl3) 150.4 (d, J = 7.7
Hz, 2C, C13), 149.9 (d, J = 8.1 Hz, 2C, C1), 137.3 (d, J = 6.9 Hz, 2C, C7), 134.2 (s, 2C,
C10), 131.0 (s, 2C, C8), 130.8 (s, 2C, C3), 130.4 (s, 1C, C15), 128.6 (d, J = 15,8 Hz, 2C,
C9), 125.5 (s, 2C, C5), 125.3 (s, 2C, C4), 124.4 (d, J = 12,4 Hz, 2C, C11), 122.6 (d, J =
12.2 Hz, 2C, C6), 121.3 (d, J = 185 Hz, 2C, C12), 120.5 (d, J = 6.1 Hz, 2C, C2), 117.7
(s, 2C, C14), 113.8 ppm (d, J = 3.8 Hz, 1C, C16); IR (KBr) v˜: 3110.9 (w, Ar-H), 3066.1
(w, Ar-H), 1594.9 (vs, C C), 1558.9 (m, C C), 1475.8 (vs, C C), 1448.1 (w), 1430.6
(m, P-Ar), 1289.4 (s, P O), 1273.5 (vs, P O), 1243.4 (s, C O), 1203.0 (m), 1132.6 (m),
1118.3 (s), 979.5 (s, P O), 948.9 (vs, P O), 907.1 (s), 793.1 (s), 748.5 (vs, C H bend),
712.1 (m), 692.3 (m), 601.3 (w), 533.4 (s), 495.9 (m); HRMS (EI) calc. for [12C30H20P2O6]
12
538.0735, found [12C30H20P2O6] 538.0776; Anal. Calcd. For C30H20P2O6: C 66.92, H
3.74; found: C 66.97, H 3.86.
Synthesis of 6-phenoxy-6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide 3: mp: 98
◦C–102 ◦C; 31P NMR (101 MHz; CDCl3): 7.16 ppm (s, 1P); 1H NMR (400 MHz, CDCl3):
7.95 (dd, JP-H = 14.9 Hz, J = 7.5 Hz, 1H, H8), 7.90–7.83 (m, 2H, H11/5), 7.62 (t, J =
7.5 Hz, 1H, H10), 7.42 (td, J = 7.3 Hz, JP-H = 3.6 Hz, 1H, H9), 7.32–7.26 (m, 1H, H3),
7.23 (t, J = 7.5 Hz, 1H, H4), 7.20–7.12 (m, 4H, H2/15), 7.05 (t, J = 7.6 Hz, 1H, H16),
6.98–6.96 ppm (m, 2H, H14); 13C NMR (100 MHz; CDCl3) 148.9–148.6 (m, 2C, C12/13),
136.0 (d, J = 7.1 Hz, 1C, C7), 133.76 (d, J = 2.5 Hz, 1C, C10), 129.7 (d, J = 9.3 Hz, 1C,
C8), 129.6 (s, 1C, C3), 128.6 (s, 2C, C15), 127.3 (d, J = 15.8 Hz, 1C, C9), 124.2 (s, 2C,
C5/16), 123.9 (s, 1C, C4), 123.0 (d, J = 12.4 Hz, 1C, C11), 121.5 (d, J = 12.5 Hz, 1C, C6),
120.5 (d, J = 177 Hz, 1C, C12), 119.6–119.7 (m, 2C, C14), 119.2 ppm (d, J = 6.9 Hz, 1C,
C2); IR (KBr) v˜: 3064 (w, Ar-H), 3019 (w, Ar-H), 2963 (w, R-H), 1609 (s, C C), 1596
(m, C C), 1488 (s, CH2), 1477 (m, CH2), 1430 (m, P-Ar), 1286, 1275 (vs, P O), 1242
(s, C O), 1196, 1169, 1078 (m, C O), 1048, 1003, 973 (vs, P O), 925 (vs, P O), 796,
764 (m, C–H bend), 743, 729, 615, 536, 493 cm−1; HRMS (EI) calc. for [12C18H13O331P]
308.0602, found [12C18H15O331P] 308.0572.
Synthesis of 6-isopropoxy-6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide 4: mp: 107
◦
1
◦C–108 C; 31P NMR (101 MHz; DMSO-d6): 9.74 ppm (s, 1P); H NMR (400 MHz,
CDCl3): 7.90 (dd, JP-H = 16,3 Hz, J = 7,6 Hz, 1H, H8), 7.89–7.84 (m, 2H, H11/5), 7.63
(t, J = 7.3 Hz, 1H, H10), 7.43 (td, J = 7.3 Hz, JP-H = 3.5 Hz, 1H, H9), 7.30 (t, J = 7.3 Hz,
1H, H3), 7.18 (t, J = 7.8 Hz, 1H, H4), 7.15 (d, J = 8.1 Hz, 1H, H2) 4.86 (m, 1H, H13),
1.12 ppm (dd, JP-H = 9.5 Hz, J = 6.1 Hz, 6H, H14); 13C NMR (100 MHz, CDCl3-d6):
150.2 (d, J = 7.8 Hz, 1C, C1), 137.1 (d, J = 6.9 Hz, 1C, C7), 133.4 (d, J = 2.4 Hz, 1C,
C10), 130.5 (s, 1C, C3), 130.2 (d, J = 9.2 Hz, 1C, C8), 128.4 (d, J = 15.4 Hz, 1C, C9),
125.4 (s, 1C, C5), 124.7 (s, 1C, C4), 124.32 (d, J = 12.1 Hz, 1C, C11), 122.8 (d, J =
12.1 Hz, 1C, C6), 121.0 (d, J = 190 Hz, 1C, C12), 120.3 (d, J = 6.5 Hz, 1C, C2), 72.3
(d, J = 6.7 Hz, 1C, C13), 24.1–23.9 ppm (m, 2C, C14); IR (KBr) v˜: 3056 (w, Ar-H), 2979

796
S. WAGNER ET AL.
(w, R-H), 1477 (m, CH2), 1432 (m, P-Ar), 1386, 1275 (s, P O), 1240 (s, C O), 1204,
1157, 1099 (s, C O), 1047, 973 (s, P O), 920 (s, P O), 795, 759 (m, C H bend), 601,
551, 521 cm−1; HRMS (EI) calc. for [12C15H15O331P] 274.0759, found [12C15H15O331P]
274.0691.
6-(2,5-dihydroxyphenyl)-6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide 5 was com-
pared to the literature by Wang and co-workers.33 The synthesis of 6H-dibenzo[c,e][1,2]
oxaphosphinine 6-sulfide 6 and of 6-(2,5-dihydroxyphenyl)-6H-dibenzo[c,e][1,2]oxaphos
phinine 6-sulfide 7 was performed as previously described by the authors.35
6-(2,5-dihydroxyphenyl)-6H-dibenzo[c,e][1,2]oxaphosphinine 6-oxide (5): 31P
1
NMR (101 MHz, DMSO-d6) 19.6 ppm (s, 1P); H NMR (400 MHz DMSO-d6): 9.46
(s, 1H, H19), 8.22 (s, 1H, H20), 8.20 (dd, J = 8.2 Hz, J = 5.2 Hz, 1H, H11), 8.18
(dd, J = 7.8 Hz, J = 1.5 Hz, 1H, H5), 7.69 (t, J = 7.9 Hz, 1H, H10), 7.55 (dd, J =
14.4, J = 14.4, 1H, H8), 7.46 (dt, J = 7.5 Hz, J = 2.7 Hz, 1H, H9), 7.40 (t, J = 7.9 Hz,
1H, H3), 7.25 (t, J = 7.6 Hz, 1H, H3), 7.25 ppm (d, J = 8.0 Hz, 1H, H2); 13C NMR
(101 MHz, DMSO-d6) 153.4 (d, J = 2.5 Hz, 1C, C17), 150.2 (s, 1C, C14), 150.1 (d, J
= 4.2 Hz, 1C, C1), 135.4 (d, J = 5.4 Hz, 1C, C7), 133.4 (s, 1C, C10), 131.2 (s, 1C, C3),
130.8 (d, J = 12.3 Hz, 1C, C8), 129.0 (d, J = 12.9 Hz, 1C, C9), 126.3 (d, J = 129.5 Hz,
1C, C12), 126.0 (s, 1C, C5), 124.4 (s, 1C, C4), 124.2 (d, J = 9.3 Hz, 1C, C11), 123.3
(s, 1C, C16), 121.8 (d, J = 11.4 Hz, C6), 120.5 (d, J = 6.0 Hz, 1C, C2), 119.2 (d, J =
8.6 Hz, 1C, C16), 118.0 (d, J = 10.2 Hz, 1C, C15), 115.2 ppm (d, J = 142.6 Hz, 1C,
C13).
6H-Dibenzo[c,e][1,2]oxaphosphinine 6-sulfide (6): mp: 88 ◦C; 31P NMR (101 MHz,
1
CDCl3) 57.1 ppm (s, 1P); H NMR (400 MHz, CDCl3) 8.37 (d, J = 536.8 Hz, 1H, HP),
7.95 (dd, J = 15.9 Hz, J = 7.6 Hz, 1H, H11), 7.8 (d, J = 8.1 Hz, 1H, H5), 7.81 (dd, J = 7.9
Hz, J = 5.1 Hz, 1H, H8), 7.66 (dt, J = 7.7 Hz, J = 1.1 Hz, 1H, H10), 7.52 (dt, J = 7.5 Hz,
J = 3.2 Hz, 1H, H9), 7.35 (dt, J = 8.4 Hz, J = 1.1 Hz, 1H, H3), 7.24 (dt, J = 8.0 Hz, J =
0.8 Hz, 1H, H4), 7.21 ppm (dd, J = 8.1 Hz, J = 0.9 Hz, 1H, H2); 13C NMR (101 MHz,
CDCl3) 149.7 (d, J = 11.2 Hz, 1C, C1), 135.7 (d, J = 5.4 Hz, 1C, C7), 134.9 (s, 1C,
C10), 131.7 (d, J = 14.0 Hz, 1C, C8), 131.1 (s, 1C, C3), 129.0 (d, J = 14.7 Hz, 1C, C9),
125.6 (d, J = 5.2 Hz, 1C, C5), 125.4 (s, 1C, C12), 124.9 (d, J = 10.4 Hz, 1C, C2), 124.2
(d, J = 9.5 Hz, 1C,C11), 123.6 (d, J = 13.5 Hz, 1C, C6), 120.8 ppm (d, J = 5.9 Hz,
1C, C2).
2-(1◦0-Thioxo-10H-9-oxa-10λ5-phosphaphenanthren-10-yl) benzene-1,4-diol (7):
1
mp.: 127 C; 31P NMR (101 MHz, DMSO-d6) 73.6 ppm (s, 1P); H NMR (400 MHz,
DMSO-d6) 9.53 (s, 1H, H19), 9.21 (s, 1H, H20), 8.11 (d, J = 7.8 Hz, 1H, H5), 8.12–8.09
(m, H11), 7.63 (dt, J = 6.6 Hz, J = 1.3 Hz, 1H, H10), 7.47–7.36 (m, 4H, H8, H9, H18,
H3), 7.24 (dt, J = 7.2 Hz, J = 0.8 Hz, 1H, H4), 7.18 (dd, J = 8.1 Hz, J = 0.6 Hz, 1H, H2),
6.85 (dd, J = 8.7 Hz, J = 2.8 Hz, 1H, H16), 6.58 ppm (t, J = 5.6 Hz, 1H, H15); 13C NMR
(101 MHz, DMSO-d6) 152.5 (s, 1C, C17), 150.0 (d, J = 18.2 Hz, 1C, C14), 149.7 (d, J =
9.8 Hz, 1C, C1), 134.0 (d, J = 4.6 Hz, 1C, C7), 132.8 (s, 1C, C10), 131.1 (s, 1C, C3),
130.1 (d, J = 14.2 Hz, 1C, C8), 129.2 (d, J = 106.4 Hz, 1C, C12), 129.2 (d, J = 14.6 Hz,
1C, C9), 126.1 (s, 1C, C11), 125.1 (s, 1C, C4), 124.2 (d, J = 8.8 Hz, 1C, C5), 123.4 (s, 1C,
C16), 122.5 (d, J = 12.4 Hz, 1C, C6), 121.0 (d, J = 5.8 Hz, 1C, C2), 120.4 (d, J = 14.2
Hz, 1C, C18), 118.1 (d, J = 9.2 Hz, 1C, C15), 116.8 (d, J = 111.8 Hz, 1C, C13); IR (KBr)
v˜: 3267 (br, -OH), 3190 (s, Ar-H), 1591 (s, P-Ar), 1580, 1471, 1221 (vs, P O), 1182 (vs,
P O), 901 (vs, P = S), 752 cm−1; HRMS (EI) calcd. for [12C18H13PO3S]+ 340.0326,
found 340.0323; Anal. Calcd. for C18H13PO3S: C 63.52, H 3.85. Found: C 63.22,
H 4.15.

SPECTRAL ASSIGNMENT OF PHENANTHRENE DERIVATIVES
797
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