2-(Trimethylsilyl)-λ3-Phosphinine: Synthesis, Coordination Chemistry, and Reactivity

Article abstract of DOI:10.1002/chem.201704539

The [4+2] cycloaddition reaction between 2-pyrone and Me₃Si?C≡P gives the corresponding 2-(trimethylsilyl)-λ³-phosphinine in good yields as a rather air and moisture stable, colorless oil. Insight into the regioselectivity of the pericyclic reaction was obtained with the help of deuterium-labeling experiments. The silyl-phosphinine acts as a ligand for the preparation of a Cu(I) and the first crystallographically characterized phosphinine-Ag(I) complex. The title compound was further used as a starting material for an alternative preparation of the parent phosphinine C₅H₅P by means of protodesilylation with HCl. C₅H₅P reacts with CuBr?S(CH₃)₂ to give an infinite Cu(I)Br coordination polymer. DFT calculations shed light on the influence of the -Si(CH₃)₃ group on the electronic properties of the aromatic phosphorus heterocycle.

Full text of DOI:10.1002/chem.201704539

A Journal of
Accepted Article
Title: 2-(Trimethylsilyl)-λ3-Phosphinine: Synthesis, Coordination
Chemistry and Reactivity
Authors: Christian Müller, Marija Habicht, Friedrich Wossidlo, Tobias
Bens, and Evgeny Pidko
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2-(Trimethylsilyl)-λ3-Phosphinine: Synthesis, Coordination
Chemistry and Reactivity
Marija H. Habicht,[a] Friedrich Wossidlo,[a] Tobias Bens,[a] Evgeny A. Pidko,[b] and Christian Müller*[a]
Abstract: The [4+2] cycloaddition reaction between 2-pyrone and
Me3Si-C≡P gives the corresponding 2-(trimethylsilyl)-λ3-phosphinine
in good yields as a rather air and moisture stable, colorless oil.
Insight into the regioselectivity of the pericyclic reaction was
obtained with the help of deuterium-labeling experiments. The silyl-
phosphinine acts as a ligand for the preparation of a Cu(I)- and the
first crystallographically characterized phosphinine-Ag(I)-complex.
The title compound was further used as starting material for an
alternative preparation of the parent phosphinine C5H5P by means of
protodesilylation with HCl. C5H5P reacts with CuBr۰S(CH3)2 to give
an infinite Cu(I)Br coordination polymer. DFT calculations shed light
on the influence of the -Si(CH3)3 group on the electronic properties of
the aromatic phosphorus heterocycle.
(Figure 1).[9,10] The sterically demanding -Si(CH3)3 group can
also influence drastically the coordination properties of a
phosphinine and leads, in the extreme case, to a change in
coordination mode from η1 (via the phosphorus lone pair) to η6
(via the aromatic ring).[11] Le Floch and Mézailles showed that
the protodesilylation of 2,6-disubstituted silylphosphinines (type
A) generates quantitatively the corresponding R-substituted
phosphinines.[12] Depending on the synthetic route, silyl-
substituents offer the possibility to prepare diphosphinines of
type B (Figure 1), triphosphinines of type C or even macrocycles
of type D, containing three or four phosphinine units.[12] Silyl-
groups can also serve for Hiyama coupling reactions between
(hetero)arenes.[14]
Introduction
Although known for more than fifty years, low-coordinate
phosphorus compounds have recently regained noticeable
interest due to their peculiar stereo-electronic properties, which
differ significantly from the characteristics of “classical” trivalent
P(III) species. Especially during the last two decades, such
fascinating molecules containing P=C double bonds have been
successfully employed in more applied research fields, e.g. in
homogeneous catalysis, luminescent molecular materials,
phosphorus-containing oligomers and polymers, dendrimers and
supramolecular chemistry.[1-6] Our group has been interested for
a long time in the aromatic λ3,σ2-phosphinines and could
contribute to their chemistry with the synthesis of a series of
donor-functionalized, cyclometalated as well as axially chiral
heterocycles.[7]
Figure 1. Silyl-substituted phosphinines.
To date, several synthetic routes to phosphinines have been
reported in literature.[1a,2e,7i,8] They individually offer the possibility
to realize different substitution pattern and to introduce
functionalities into specific positions of the 6-membered,
aromatic ring. Among those compounds, silyl-substituted
phosphinines are particularly interesting, as they provide access
to phosphinines with rather special properties. As a matter of
fact, a -Si(CH3)3 substituent can modify the electronic properties
of phosphinines substantially, as evident from a comparison of
the 31P{1H} NMR spectra of the parent phosphinine C5H5P and
Substituted phosphinines of type E, containing only one -
Si(CH3)3 group in α-position to the phosphorus atom, are less
common.[11,15] We have recently reported on the preparation and
functionalization of the 2-(trimethylsilyl)-6-bromo-phosphinine F,
which was obtained by a [4+2] cycloaddition reaction between 3-
bromo-2-pyrone and trimethylsilyl-phosphaalkyne (Me3Si-
C≡P).[16,17] Although 2-(trimethylsilyl)-λ3-phosphinine 1 has been
mentioned in
a single literature reference, no synthetic
procedure for this compound has been reported to date.[18] We
therefore started to investigate the synthesis, coordination
chemistry and reactivity of the title compound 1 in more detail.
the 2,6-bis(trimethylsilyl-)phosphinine derivatives of type
A
[a]
[b]
M. Sc. M. H. Habicht, M. Sc. Friedrich Wossidlo, M. Sc. T. Bens,
Prof. Dr. C. Müller
Institut für Chemie und Biochemie
Freie Universität Berlin
Fabeckstr. 34/36
E-mail: c.mueller@fu-berlin.de
Prof. Dr. E. A. Pidko
Results and Discussion
Based on our previously reported synthesis of compound F, 2-
pyrone reacts cleanly in a [4+2] cycloaddition reaction with
freshly prepared Me3Si-C≡P as a solution in toluene towards the
ITMO University
Lomonosova 9, St. Petersburg, 191002, Russia
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corresponding 2-(trimethylsilyl)-phosphinine 1, according to
Scheme 1. Any remaining excess of 2-pyrone and impurities can
easily be removed by flash-chromatography, giving 1 in good
yields as a pure, colorless liquid, which is surprisingly rather
stable towards air and moisture and can be handled without
taking any particular precautions.
original preparation of 2-(tert-butyl)-phosphinine by Regitz and
co-worker via this particular route.[21]
We thus anticipated, that deuterium-labeling experiments might
offer the opportunity to reveal in which ratio the two regioisomers
are formed. 3-Bromo-2-pyrone 2 was therefore reacted with Zn
powder in deuterated acetic acid as solvent.[22] The labeled 3-
deutero-2-pyrone 3 was obtained in 93% isotopically purity
(Scheme 2). In analogy to the preparation of 1, compound 3 was
reacted with Me3Si-C≡P, which should result in the formation of
the two deuterium-labeled regioisomers 4 and 5, according to
Scheme 2. Indeed, the 31P{1H} NMR spectrum of the reaction
mixture reveals the presence of three phosphorus-containing
species (Figure 3).[23] The single resonance at δ(ppm) = 231.9
can be attributed to the unlabeled phosphinine 1. The two
Scheme 1. Synthesis of 2-(trimethylsilyl)-λ3-phosphinine 1.
remaining species both show a triplet at δ(ppm) = 230.8 (JP-D
=
1.5 Hz) and 230.5 (JP-D = 5.8 Hz), respectively, and in a ratio of
1:4. Due to the significant larger P-D-coupling constant, the
signal at δ(ppm) = 230.5 (main product) can therefore be
assigned to phosphinine 4, while the signal at δ(ppm) = 230.8
(minor product) is characteristic for phosphinine 5.
1
The H NMR spectrum of 1 in CD2Cl2 shows the expected four
resonances of the hetereocycle in the aromatic region and a
doublet (4JH-P = 0.8 Hz) for the -Si(CH3)3 group at δ(ppm) = 0.33
(Figure 2). The doublet of doublet at δ(ppm) = 8.81 can be
assigned to the Hα-atom due to the large coupling constant JH-P
of 16.2 Hz. The 31P{1H} NMR spectrum of 1 shows a single
resonance at δ(ppm) = 230.7.
2
Scheme 2. Regioselectivity of the [4+2] cycloaddition reaction between 3 and
Me3Si-C≡P.
Figure 2. 1H NMR spectrum of 1 (CD2Cl2).
Our previous investigations indicated that the [4+2] cycloaddition
reaction between phosphaalkynes and substituted 2-pyrones
under formation of 2-substituted phosphinines is not
regioselective and most likely dominated by steric factors.[16,19]
Similar observations were made when 2-pyrone was reacted
with unsymmetrically substituted alkynes under poor
regiocontrol.[20] While this is irrelevant for reactions with the
unsubstituted 2-pyrone and a phosphaalkyne, as only identical
α-substituted phosphinines are formed, it is of crucial importance
for smaller substituents at the 2-pyrone moiety. As a matter of
fact, depending on how the phosphaalkyne approaches the
substituted 2-pyrone, two possible regioisomers can be formed.
Interestingly, any investigations on this regioselectivity-problem
have so far been remained elusive in the literature since the
Figure 3. 31P{1H} NMR of the reaction mixture produced by the [4+2]
cycloaddition between 3 and Me3Si-C≡P.
At this point and in analogy to literature reports, we assume that
the [4+2] cycloaddition reaction of 3 with Me3Si-C≡P proceeds
via the intermediates 6 and 6’, depending on the orientation of
the approaching phosphaalkyne with respect to the diene-
system (Scheme 3). However, intermediate 6’ is obviously
preferentially formed which, under release of CO2, produces the
major product 4. Nevertheless, it should be noted here that the
second regioisomer 5 is indeed formed in a significant amount
as well. Only larger substituents in 3- or 6-position of a
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substituted 2-pyrone can enforce the exclusive formation of only
one regioisomer as reported in literature before.[16,19,20]
The crystallographic characterization of 7 reveals the formation
of a bromido-bridged dimer of the type [(1)2CuBr]2 according to
Scheme 4. Despite the fact that an equimolar ratio of the
phosphinine and the Cu(I) source was used, the observed dimer
is obviously preferentially formed upon crystallization.
Interestingly, when starting from a 2:1 mixture of 1 and
CuBr۰S(CH3)2 the clear yellow solution shows the same
chemical shift of δ = 190.0 ppm in the 31P{1H} NMR spectrum,
while no unreacted metal precursor can be detected. It should
be mentioned here that the structural motif found for 7 is so far
unprecedented in phosphinine-copper chemistry.
Scheme 3. Formation of the regioisomers 4 and 5 by [4+2] cycloaddition
between 3 and Me3Si-C≡P.
Phosphinines readily react with Cu(I) salts and several structural
motifs, ranging from infinite stair polymer and infinite chain
structures to phosphinine-bridged copper dimers, tetranuclear
and heterocubane clusters were reported in the literature.[4a,e, 24-
With polydentate phosphinine-based ligands, also
mononuclear Cu(I) complexes are accessible.[28]
Scheme 4. Reaction of 1 with CuBr۰S(CH3)2 under formation of the bromide-
bridged Cu(I)-dimer 7.
27]
We therefore decided first to synthesize a phosphinine-Cu(I)-
complex by reacting silyl-phosphinine 1 with CuBr۰S(CH3)2 in
THF and in a ratio of 1:1. In the 31P{1H} NMR spectrum of the
reaction mixture, which still shows the presence of unreacted
metal precursor, a signal at δ(ppm) = 190.0 can be detected.
The coordination shift difference of Δδ = 40.7 ppm to higher field
indeed indicates the formation of a coordination compound.
However, a fluxional behavior is apparently present in solution,
as the observed resonance in the 31P{1H} spectrum is slightly
broadened. After filtration of the reaction mixture, we could
obtain yellow crystals, suitable for X-ray diffraction, by layering a
saturated solution of the product in THF with pentane.
Even though the synthesis of phosphinine-Ag(I) complexes has
been documented before, no structural information of such
coordination compounds has been reported in literature until
now.[24,29] We therefore attempted to react silyl-phosphinine 1
with AgOTf in CH2Cl2. The product shows a single resonance in
the 31P{1H} NMR spectrum at δ(ppm) = 180.0 and thus a
coordination shift difference of Δδ = 50.7 ppm to higher field.
From a concentrated solution of the coordination compound in
THF, single crystals, suitable for X-ray diffraction could be
obtained. The phosphinine-Ag(I) complex 8 crystallizes in the
triclinic space group P1̅ and the molecular structure in the crystal,
along with selected bond lengths and angles, is depicted in
Figure 5. Interestingly, the X-ray crystal structure analysis of 8
shows the presence of a phosphinine-Ag(I) hexamer of the type
{[(1)Ag]OTf}6 in the solid state and is the first crystallographically
characterized Ag(I) complex of a phosphinine. A closer look to
the graphical representation of 8 displays a highly symmetrical
hexamer containing three different types of phosphinine ligands
as well as three different types of Ag(I) cations. As a matter of
fact, there are a total of two phosphinines, which coordinate via
the phosphorus lone-pair in an η1-fashion to the Ag(I) cations
Ag(2) and Ag(2)_i. In these fragments, the Ag(I) cations are only
three-coordinate, with the remaining two coordination sites
Compound 7 crystallizes in the triclinic space group P1̅ and the
molecular structure is depicted in Figure 4, along with selected
bond lengths and angles.
-
occupied by an oxygen atom of two CF3SO3 counteranions.
Likewise, a total of two terminal phosphinines coordinate via the
phosphorus lone-pair to the Ag(I)-cations Ag(3) and Ag(3)_i,
while the remaining two phosphinines act as bridging ligands in
an η2-fashion for the two Ag(I)-ions of each dimer. In contrast to
“classical” phosphorus(III) ligands, this bridging coordination
mode has occasionally been observed in the coordination
chemistry of phosphinines and is enabled by the more diffuse
and less-directional lone-pair of the formally sp2-hybridized
phosphorus atom compared to the formally sp3-hybridized donor
Figure 4. Molecular structure of 7 in the crystal. Displacement ellipsoids are
shown at the 50% probability level. Selected bond lengths (Å), distances (Å)
and angles (°): P(2)-C(9): 1.723(3); P(2)-C(13): 1.722(3); C(9)-C(10): 1.402(4);
C(10)-C(11): 1.395(4); C(11)-C(12): 1.386(5); C(12)-C(13): 1.374(5); Si(2)-
C(9): 1.895(3); Cu(1)-P(1): 2.2276(8); Cu(1)-P(2): 2.2402(8); Cu(1)-Br(1):
2.4861(4); Cu(1)·۰۰Cu(1)_i: 2.9669(7). C(9)-P(2)-C(13): 104.82(15).
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atom in trivalent phosphorus compounds.[2a,b,4e, 27] The formation
of 8 and the respective connectivity is illustrated in Scheme 5.
theoretically.[12] On the other hand, there are only a few synthetic
methods known for the preparation of the unsubstituted
phosphinine 9, with the tin-route reported by Ashe III as the most
elegant, but rather tedious procedure.[9, 31]
Scheme 6. Protodesilylation of 1 with HCl in diethylether to produce the parent
phosphinine 9.
We therefore dissolved 1 in dry diethylether and added an
excess of a solution of HCl in Et2O. The reaction mixture was
stirred at T = 50°C for 3 d and subsequently concentrated under
vacuum. With the help of a puriflash-system, we were indeed
able to obtain the pure, parent phosphinine 9 as a solution in
pentane, while its concentration could easily be determined by
1
integrating the corresponding signals in the H NMR spectrum.
Further removal of the solvent pentane is neither necessary nor
advisable due to the low boiling point of C5H5P. Figure 6
illustrates a comparison of the H NMR spectra of the starting
material 1 (a) and the product 9 (b, only the aromatic region is
shown).
Figure 5. Molecular structure of 8 in the crystal. Displacement ellipsoids are
shown at the 50% probability level. Selected bond lengths (Å), distances (Å)
and angles (°): P(1)-C(1): 1.722(3); P(1)-C(5): 1.709(3); P(2)-C(10): 1.717(3);
P(2)-C(14): 1.711(3); P(3)-C(19): 1.725(3); P(3)-C(23): 1.713(3); Si(1)-C(1):
1.886(3); Si(2)-C(10): 1.882(3); Si(3)-C(19): 1.888(3); P(1)-Ag(1): 2.4016(15);
P(1)-Ag(3)_i: 2.5043(15); P(2)-Ag(2): 2.3351(19); P(3)-Ag(3): 2.4218(15);
Ag(1)-O(1): 2.363(3); Ag(1)-O(4): 2.333(2); Ag(3)-O(8) 2.323(2); Ag(2)-O(7):
2.302(2); Ag(2)-O(5): 2.397(2); Ag(1)۰۰۰Ag(3)_i: 2.9190(16). C(1)-P(1)-C(5):
106.90(15); C(10)-P(2)-C(14): 106.21(15); C(19)-P(3)-C(23): 106.16(14).
1
In addition to the absence of any resonance of a -Si(CH3)3 group
1
in the H NMR spectrum of the product, the five protons in the
aromatic region of 9 integrate to 2:2:1. The 31P{1H} NMR of 9
shows a single resonance at δ(ppm) = 206.6, which differs
significantly from the -Si(CH3)3-substituted phosphinine 1 (δ(ppm
= 230.7).
Figure 6. Comparison of the 1H NMR spectra (aromatic region) of silyl-
phosphinine 1 (a) and C5H5P (9, b).
Scheme 5. Reaction of 1 and AgOTf to form the hexamer 8.
In order to get an additional structural proof that the parent
phosphinine
9
had been formed,
a
solution of
9
in
Having successfully developed a facile synthetic route towards
dichloromethane was further reacted with CuBr۰S(CH3)2 in
dichloromethane and in a ratio of 1:1. The 31P{1H} NMR
spectrum of the reaction mixture shows a broad signal at δ(ppm)
= 169.0 and therefore a coordination shift difference of Δδ(ppm)
= 37.6. In analogy to the formation of Cu(I) complex 7 (vide
supra), a fluxional behavior can again be anticipated. Yellow
crystals of product 10, suitable for X-ray diffraction, could be
obtained after several days at T = -30°C by layering a
concentrated solution of the coordination compound in
dichloromethane with diethylether. The copper complex 10
2-(trimethylsilyl)-phosphinine
1
and having started initial
experiments concerning its coordination chemistry, we were
finally wondering whether the protodesilylation of 1 would offer
an alternative approach for the preparation of the parent
compound C5H5P (9), which has been reported to be a volatile,
air- and moisture sensitive, colorless oil (Scheme 6).[9] The
coordination chemistry of
Elschenbroich and co-worker.[30]
As mentioned above, protodesilylation reactions on substituted
silyl-phosphinines have been studied both experimentally and
9
has been documented by
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crystallizes in the monoclinic space group P21/c and the
molecular structure is depicted in Figure 7a-c, along with
selected bond lengths and angles.
Mathey and co-workers for the Cu(I)Br complex containing the
2-hydroxy-phosphinine ligand.[27]
Scheme 7. Reaction of
coordination polymer 10.
1 with CuBr۰S(CH3)2 under formation of the
A closer look to the phosphinine-Cu(I) fragment in 10 further
reveals, that the P-Cα and P-Cu bond lengths are very similar to
the values found in complex 7, containing the silyl-phosphinine 1,
as well as for Mathey’s Cu(I)Br complex containing the 2-
hydroxy-phosphinine ligand.[27]
As silyl-phosphinine 1 turned out to be a rather interesting and
versatile compound with respect to its synthesis, stability,
handling, coordination chemistry and reactivity, we finally,
wanted to get an insight into the influence of the -Si(CH3)3 group
on the electronic properties of the aromatic phosphorus
heterocycle. Numerous studies have shown that silyl
substituents of the type SiHn(CH3)3-n, which are directly attached
to π-electron systems, function as weak π-acceptors by a
conjugative mechanism (“inverse” hyperconjugation).[32] On the
other hand, a more recent theoretical study by García de la
Vega and co-worker on silyl-substituted phosphinine
macrocycles revealed, that ortho-Si(CH3)3 substitution in
phosphinines improve both their σ-donating and π-accepting
properties.[33 We therefore performed theoretical calculations on
the DFT level on the parent phosphinine 9 and its silyl-derivative
1.[34] A graphical representation of the frontier orbitals of both
compounds is illustrated in Figure 8.
Figure 7. Molecular structure of 10 in the crystal. Displacement ellipsoids are
shown at the 50% probability level. a) asymmetric unit of 10, b) coordination
polymer, c) view along the CuBr-chain. Selected bond lengths (Å), distances
(Å) and angles (°): P(1)-C(1): 1.713(2); P(1)-C(5): 1.717(2); C(1)-C(2):
1.392(3); C(2)-C(3): 1.387(4); P(2)-C(6): 1.718(3); P(2)-C(10): 1.725(2); C(3)-
C(4): 1.394(3); C(4)-C(5): 1.388(3); C(6)-C(7): 1.386(3); C(8)-C(7): 1.387(3);
C(8)-C(9): 1.389(3); C(9)-C(10): 1.383(3); Cu(1)-Br(1): 2.5063(4); Cu(1)-P(1):
2.2452(6); Cu(1)-P(2): 2.2323(7). C(1)-P(1)-C(5): 102.92(11); C(6)-P(2)-C(10):
102.37(11).
The crystallographic characterization of 10 nicely verifies, that
the parent phosphinine 9 can indeed cleanly be formed by
protodesilylation of 1 and shows the presence of a [(9)2CuBr]
fragment in the asymmetric unit (Figure 7a). The Cu(I) center
adopts a trigonal pyramidal coordination geometry and contains
two independent phosphinine ligands and one bromide ligand. In
order to complete the fourth coordination site at the Cu(I) ion,
the [(9)2CuBr]-units form infinite chains, as depicted in Figure 7b
and Scheme 7.
As obvious from Figure 7c (view along the chain), the
phosphinine rings of each [(9)2CuBr]-fragment are not oriented
in a parallel way, but retain strictly alternate positions along the
CuBr-fragments, resulting in a regularly distorted chain. A similar
and rather rare structural motif has also been reported by
Figure 8. Comparison of the frontier orbitals of 1 and 9. nP indicates the lone
pair at the phosphorus atom. DFT functional/basis set: B3LYP/6-311+G(d,p).
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The computational results show, that the ortho-Si(CH3)3
substitution in 9 apparently does not affect significantly the
energy level of the LUMO upon introducing the silyl-group (-
1.705 eV vs. -1.659 eV in 1), indicating no major difference in
the title compound are significantly improved with respect to
C5H5P, the π-acceptor properties of both phosphinines are very
similar.
the π-accepting properties of
1 in comparison to the
unsubstituted phosphinine 9. Most strikingly, however, is a
change of the orbital sequence of the HOMO-1 and HOMO-2,
once the -Si(CH3)3 group is introduced. While the phosphorus
lone-pair is represented by the HOMO-2 in the parent compound
C5H5P, it becomes the HOMO-1 in silyl-phosphinine 1, which is
much higher in energy compared to 9 (-7.568 eV vs. -7.335 eV).
Consequently, 1 has to be regarded as a much better σ-donor
compared to the parent phosphinine, which is in line with our
Experimental Section
General: All reactions were performed under an argon atmosphere in
oven-dried glassware using modified Schlenk techniques unless
otherwise stated. All common solvents and chemicals were commercially
available. Trimethylsilylphosphaalkyne[17], 2-pyrone[37] and 3-bromo-2-
pyrone 2[37,387] were prepared according to literature procedures. The
solvents DCM, n-pentane and toluene were prepared by using MBraun
Solvent Purification System MB-SPS 800 filled with Al2O3. Et2O was
dried over Na/benzophenone and THF over K/benzophenone under
argon. The deuterated dry solvents benzene-d6 and DCM-d2 were dried
over CaH2 and THF-d8 over sodium-potassium alloy. Silica gel plates 60
F254 from Merck were used for thin layer chromatography and silica gel
60 M (0.04-0.063 mm) from Macherey-Nagel was used for preparative
column chromatography unless otherwise stated. 1H, 13C and 31P NMR
spectra were recorded by using a Jeol JNM-ECA 400II spectrometer. 1H
and 13C{1H} chemical shifts are referenced to the residual proton
resonance of the deuterated solvents[39] and 31P{1H} chemical shifts are
referenced to an 85% aqueous solution of H3PO4. Electron impact mass
spectra (EI-MS) were recorded on a Variant MAT 711 spectrometer and
electrospray ionization mass spectra (ESI-MS) were recorded on a
FTICR mass spectrometer from Variant.
previous
observations
concerning
silyl-phosphinines.[35]
Interestingly, the addition of a second ortho-Si(CH3)3 group in 6-
position of the heterocycle leads to an even further increase of
the HOMO-1 level (lone-pair) compared to 9 (-7.142 eV vs. -
7.335 ev).[36] This drastic change in electronic properties,
especially with respect to σ-donation, can lead to interesting
phenomena concerning the reactivity of Si(CH3)3-substituted
phosphinines in future investigations.
Conclusions
We have developed a facile access to an ortho-Si(CH3)3
substituted phosphinine by a [4+2] cycloaddition of 2-pyrone with
(CH3)3Si-C≡P. The silyl-phosphinine can be obtained in good
yields as a colorless oil. It turned out, that this aromatic
phosphorus heterocycle is rather stable towards air and
moisture and can be handled without taking any special
precautions. This property contrasts the reported sensitivity of
the parent phosphinine C5H5P. Starting from a deuterated 2-
pyrone derivative, we could retrieve information on the
regioselectivity of the pericyclic reaction and could demonstrate
that two regioisomers are formed. First results on the
coordination chemistry of the silyl-phosphinine show the
formation of a bromido-bridged dimer of the type [(L)2CuBr]2
upon reaction with CuBr⋅SMe2 and subsequent crystallization.
Reaction of the ligand with AgOTf gives a phosphinine-Ag(I)
complex, which forms a hexamer of the type {[(L)Ag]OTf}6 in the
solid state. This coordination compound is the first
crystallographically characterized phosphinine-Ag(I) complex. By
means of protodesilylation we could further demonstrate an
alternative synthetic route towards the parent phosphinine
C5H5P, by reaction of the silyl-phosphinine with hydrochloric acid
in diethylether. C5H5P can be isolated as a pentane solution of
known concentration and without the presence of any
byproducts. The reaction of C5H5P with CuBr⋅SMe2 leads to an
infinite phosphinine-based Cu(I)Br coordination polymer, which
was structurally characterized by means of single crystal X-ray
diffraction. We further performed theoretical calculations on the
DFT level in order to get insight into the influence of the -
Si(CH3)3 group on the electronic properties of the aromatic
phosphorus heterocycle. Remarkably, a drastic change in the σ-
donation properties was found upon introducing the ortho-
Si(CH3)3-substituent to C5H5P. While the σ-donation properties of
Synthesis of 2-(trimethylsilyl)phosphinine (1): 2-Pyrone (2.00 g, 20.9
mmol) was added to a solution of Me3Si-CP (2.43 g, 20.9 mmol) in
toluene (150 mL). The reaction mixture was heated to T = 120°C for t = 5
h resulting in a dark red solution. The solvent was removed under
reduced pressure and the crude product was purified by means of
column chromatography over silica with ethyl acetate/n-hexane (1:9)
using analytical TLC to monitor fractions. After distillation (T = 72°C, p =
15 mbar) the pure product 1 was obtained as a colorless liquid (883 mg,
26%). 1H NMR (400 MHz, chloroform-d1, 20°C): δ = 8.87 (dddd, J = 37.0,
10.0, 1.4, 0.7 Hz, 1 H, o-H), 8.12 (dddd, J = 10.1, 8.0, 2.7, 0.9 Hz, 1 H);
7.87 (dddd, J = 8.0, 8.0, 0.8, 0.6 Hz, 1 H), 7.53 (dddd, J = 8.0, 8.0, 2.9,
0.7 Hz, 1 H), 0.41 (dd, J = 0.6, 0.6 Hz, 9 H, -Si(CH3)3) ppm; 13C{1H} NMR
(101 MHz, chloroform-d1, 20°C): δ = 170.7 (d, J = 77.8 Hz, 1 C, o-C),
154.8 (d, J = 61.6 Hz, 1 C, o-C), 138.4 (d, J = 13.1 Hz, 1 C), 133.7 (d, J =
13.1 Hz, 1 C), 127.9 (d, J = 25.3 Hz, 1 C), -0.01 (d, J = 6.1 Hz, 3
C, -Si(CH3)3) ppm; 29Si{1H} NMR (80 MHz, chloroform-d1, 20°C): δ = -0.7
(d, J = 36.0 Hz) ppm; 31P{1H} NMR (162 MHz, chloroform-d1, 20°C): δ =
231.4 ppm; 31P NMR (162 MHz, chloroform-d1, 20°C): δ = 231.4 (ddd, J =
37.3, 8.1, 8.1 Hz) ppm; EI-MS (30°C, 80 eV): m/z (%) = 168.1 (22) [M]+,
153.1 (100) [M-CH3]+, 96.0 (45) [M-SiMe3]+, 68.1 (45) [C5H8]+.
Synthesis of 3-deutero-2-pyrone (3): 3 was prepared by a modified
literature procedure.[20] Pyrone 2 (0.51 g, 2.90 mmol) was added to a
suspension of Zn powder (5.22 g, 79.9 mmol) in deuterated acetic acid (4
mL). The reaction mixture was stirred at T = 80°C. After t = 48 h the
reaction mixture was quenched with water (1.5 mL), filtrated and
extracted with DCM (3 x 10 mL). The combined organic layers were
washed with water (10 mL), dried over MgSO4 and the solvent was
removed in vacuum (T = 40°C, p = 20 mbar). The crude product was
distillated (T = 90°C, p = 20 mbar) to obtain the product 3 as a colorless
liquid (94.6 mg, 34%) of 93% isotopic purity. 1H NMR (400 MHz,
chloroform-d1, 20°C): δ = 7.49 (dd, J = 5.2, 2.2 Hz, 1 H), 7.33 – 7.29 (m,
1 H), 6.21 (ddd, J = 6.3, 5.2, 0.6 Hz, 1 H) ppm.
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10.1002/chem.201704539
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Synthesis of deutero-2-(trimethylsilyl)phosphinines 4 and 5: Pyrone 3
(80.0 mg, 0.82 mmol) was added to a solution of Me3Si-CP (174 mg, 1.5
mmol) in toluene (10 mL). After refluxing the reaction mixture for t = 3 h,
all volatiles were removed in vacuum to obtain the crude product as a
colorless liquid, which was analyzed by means of NMR spectroscopy
without further purification. 4: 31P{1H} NMR (162 MHz, benzene-d6,
9.2308(6), b = 10.3251(7), c = 13.1957(8) Å; α = 91.331(2)°, β =
106.604(2)°, γ = 114.192(3)°; V = 1085.12(12) Å3; Z = 4; Dx = 1.469 g
cm-3; μ = 3.100 mm-1. 3999 reflections were measured by using a D8
Venture, Bruker Photon CMOS diffractometer[40] with a rotating anode
(MoKα radiation; λ = 0.71073 Å) up to a resolution of (sinϴ/λ) max = 0.60 Å
at a temperature of 100 K. 3999 reflections were unique (Rint = 0.0318).
The structures were solved with SHELXL-201441] by using direct methods
and refined with SHELXL-2014[41] on F2 for all reflections. Non-hydrogen
atoms were refined by using anisotropic displacement parameters. The
positions of the hydrogen atoms were calculated for idealized positions.
205 parameters were refined with one restraint. R1 = 0.0283 for 3677
reflections with I > 2σ(I) and wR2 = 0.0662 for 3999 reflections, S = 1.070,
residual electron density was between -1.76 and 0.66 eÅ-3. Geometry
calculations and checks for higher symmetry were performed with the
PLATON program.[42] CCDC 1484202 (7) contains the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
2
20°C): δ = 230.5 (t, JP-D = 5.8 Hz) ppm. 5: 31P{1H} NMR (162 MHz,
benzene-d6, 20°C): δ = 230.8 (t, 3JP-D = 1.5 Hz) ppm.
Synthesis of [(1)2CuBr]2 (7): Phosphinine 1 (20.8 mg, 0.12 mmol) was
dissolved in THF (0.9 mL) and CuBr⋅SMe2 (25.4 mg, 0.12 mmol) was
added to this solution. The reaction mixture turns immediately from
colorless to yellow. After stirring the solution for t = 30 mins at T = 21°C
the reaction mixture was filtered over Celite and the filtrate was
concentrated in vacuum to give the product 7 as a yellow crystalline solid
(30.7 mg, 82% based on phosphinine). 1H NMR (400 MHz, DCM-d2,
20°C): δ = 8.81 (dd, J = 26.5, 10.1 Hz, 1 H, o-H), 8.11 (dd, J = 19.0, 8.04
Hz, 1 H, m-H), 7.89 (ddd, J = 15.4, 9.0, 8.9 Hz, 1 H, m-H), 7.47 (dd, J =
13.5, 8.0 Hz, 1 H, p-H), 0.45 (s, 9 H, -Si(CH3)3) ppm; 31P{1H} NMR (162
MHz, THF-d8, 20°C): δ = 189.3 ppm.
X-ray crystal structure determination of 8: Crystals suitable for X-ray
diffraction were obtained from
Crystallographic data: C9H13AgF3O3PSSi; FW
0.21x0.18x0.04 mm3; colorless block, triclinic; P1
; a = 11.974(10), b =
a
saturated solution of
8 in THF.
=
425.18 g/mol;
Synthesis of {[(1)Ag]OTf}6 (8): Phosphinine 1 (14.4 mg, 0.09 mmol) was
dissolved in THF (0.7 mL) and AgOTf (20.0 mg, 0.08 mmol) was added
to this solution. After stirring the solution for t = 20 mins at T = 21°C in
darkness the reaction mixture was filtered over Celite and the filtrate was
concentrated in vacuum to give the product 8 as a colorless crystalline
solid (31.9 mg, 93%). 1H NMR (400 MHz, DCM-d2, 20°C): δ = 8.83 (dd, J
= 31.7, 10.0 Hz, 1 H, o-H), 8.31 (dd, J = 13.0, 7.8 Hz, 1 H, m-H), 8.09 (dd,
J = 9.5, 5.8 Hz, 1 H, m-H), 7.71 (d, J = 4.0 Hz, 1 H, p-H), 0.43 (s, 9 H,
Si(CH3)3) ppm; 31P{1H} NMR (162 MHz, DCM-d2, 20°C): δ = 180.8 ppm.
̅
13.276(10), c = 16.454(10) Å; α = 76.640(17)°, β = 80.730(17)°, γ =
64.13(2)°; V = 2285(3) Å3; Z = 6; Dx = 1.854 g cm-3; μ = 1.674 mm-1. 8410
reflections were measured by using a D8 Venture, Bruker Photon CMOS
diffractometer[40] with a rotating anode (MoKα radiation; λ = 0.71073 Å) up
to a resolution of (sinϴ/λ) max = 0.60 Å at a temperature of 100 K. 8410
reflections were unique (Rint = 0.0294). The structures were solved with
SHELXL-2014[41] by using direct methods and refined with SHELXL-
2014[41] on F2 for all reflections. Non-hydrogen atoms were refined by
using anisotropic displacement parameters. The positions of the
hydrogen atoms were calculated for idealized positions. 523 parameters
were refined with zero restraints. R1 = 0.0234 for 7510 reflections with I >
2σ(I) and wR2 = 0.0547 for 8410 reflections, S = 1.118, residual electron
density was between -0.60 and 0.53 eÅ-3. Geometry calculations and
checks for higher symmetry were performed with the PLATON
program.[42] CCDC 1575364 (8) contains the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Synthesis of phosphinine (9): To phosphinine 1 (350 mg, 2.08 mmol) in
Et2O (3 mL) a solution of HCl in Et2O (2 M, 5 mL, 10.0 mmol) was added
dropwise. After complete addition the reaction mixture was stirred at T =
50°C in a closed system for t = 48 h. The reaction mixture was filtrated
over Celite and the filtrate was concentrated carefully to a volume of 1
mL. The crude product was purified by means of column chromatography
over spherical silica (25 g, 15 µm) with n-pentane via a puriFlash XS
420+ system. The collected product fraction was then immediately
concentrated in vacuum (T = 21°C, p = 550 mbar) to give the product 9
as a colorless solution in n-pentane. 1H NMR (400 MHz, DCM-d2, 20°C):
δ = 8.78 (dtd, J = 37.5, 10.9, 1.0 Hz, 2 H, o-H), 7.89 (dtd, J = 10.7, 8.2,
8.2 Hz, 2 H, m-H), 7.57 (ttd, J = 8.1, 3.7, 1.0 Hz, 1 H, p-H) ppm; 13C{1H}
NMR (101 MHz, DCM-d2, 20°C): δ = 155.1 (d, J = 53.5 Hz, 2 C, o-C),
134.6 (d, J = 14.4 Hz, 2C, m-C), 129.8 (d, J = 22.1 Hz, 1 C, p-C) ppm;
31P{1H} NMR (162 MHz, DCM-d2, 20°C): δ = 206.6 ppm.
X-ray crystal structure determination of 10: Crystals suitable for X-ray
diffraction were obtained by cooling down a saturated solution of 10 in
DCM and layering with Et2O. Crystallographic data: C5H5Br0.5Cu0.5P; FW
=
167.78 g/mol; 0.55x0.19x0.19 mm3; yellow block, monoclinic; P21/c; a =
9.0843(2), b = 17.3408(3), c = 7.4264(1) Å; α = 90°, β = 92.213(6)°, γ =
90°; V = 1169.00(4) Å3; Z = 8; Dx = 1.907 g cm-3; μ = 5.516 mm-1. 2135
reflections were measured by using a D8 Venture, Bruker Photon CMOS
diffractometer[40] with a rotating anode (MoKα radiation; λ = 0.71073 Å) up
to a resolution of (sinϴ/λ) max = 0.60 Å at a temperature of 102 K. 2135
reflections were unique (Rint = 0.0230). The structures were solved with
SHELXL-2014[41] by using direct methods and refined with SHELXL-
2014[41] on F2 for all reflections. Non-hydrogen atoms were refined by
using anisotropic displacement parameters. The positions of the
hydrogen atoms were calculated for idealized positions. 127 parameters
were refined with zero restraints. R1 = 0.0206 for 1989 reflections with I >
2σ(I) and wR2 = 0.0500 for 2135 reflections, S = 1.117, residual electron
density was between -0.57 and 0.38 eÅ-3. Geometry calculations and
checks for higher symmetry were performed with the PLATON
program.[42] CCDC 1575365 (10) contains the supplementary
crystallographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Synthesis of [(9)2CuBr]∞ (10): Phosphinine 9 (11.0 mg, 0.11 mmol) was
dissolved in DCM (0.8 mL) and CuBr⋅SMe2 (23.6 mg, 0.11 mmol) was
added to this solution. The reaction mixture turns immediately from
colorless to yellow. After stirring the solution for t = 5 mins at T = 21°C
the reaction mixture was filtered over Celite and the filtrate was
concentrated in vacuum to give the product 10 as a yellow crystalline
solid (25.3 mg, 96%).1H NMR (400 MHz, DCM-d2, 20 °C): δ = 8.68 (dddd,
J = 32.6, 10.9, 1.4, 0.9 Hz, 2 H, o-H), 7.92 (m, 2 H, m-H); 7.57 (tdt, J =
8.1, 5.0, 1.0 Hz, 1 H, p-H) ppm; 13C{1H} NMR (101 MHz, DCM-d2, 20°C):
δ = 151.1 (d, J = 31.4 Hz, 2 C, o-C), 135.6 (d, J = 16.0 Hz, 2 C, m-C),
129.7 (d, J = 25.7 Hz, 1 C, p-C) ppm; 31P{1H} NMR (162 MHz, DCM-d2,
20°C): δ = 189.9 ppm.
X-ray crystal structure determination of 7: Crystals suitable for X-ray
diffraction were obtained from a saturated solution of 7 in THF by
layering with n-pentane. Crystallographic data: C8H13Br0.5Cu0.5P; FW
=
239.97 g/mol; 0.16x0.07x0.04 mm3; colorless block, triclinic; P1;
̅
a =
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10.1002/chem.201704539
Chemistry - A European Journal
FULL PAPER
DFT calculations: Density Functional Theory (DFT) calculations were
carried out at the B3LYP/6-311+G(d,p) level of theory with the Gaussian
09 D.01 program.[43] Full geometry optimization without any symmetry
constraints was performed prior to the analysis of the electronic structure
of the different phosphinine ligands. The nature of the stationary points
was evaluated from the analytically computed harmonic modes. No
imaginary frequencies were found for the optimized structures confirming
that these correspond to local minima on the potential energy surface.
806; e) M. Ghalib, P. G. Jones, C. Schulzke, D. Szieberth, L. Nyulaszi,
J. Heinicke, Inorg. Chem. 2015, 2117; f) M. Ghalib, L. Könczöl, L.
Nyulászi, G. J. Palm, C. Schulzke, J. W. Heinicke, Dalton Trans. 2015,
44, 1769; g) f) B. Niaz, B. R. Aluri, P. G. Jones, J. W. Heinicke, Eur. J.
Inorg. Chem. 2015, 3995; h) M. Ghalib, C. Schulzke, G. J. Palm, J. W.
Heinicke, J. Organomet. Chem. 2015, 776, 60.
[7]
a) C. Müller, D. Wasserberg, J.J.M. Weemers, E.A. Pidko, S. Hoffmann,
M. Lutz, A.L. Spek, S.C.J. Meskers, R.A. Janssen, R.A. van Santen, D.
Vogt, Chem. Eur. J. 2007, 13, 4548; b) C. Müller, E.A. Pidko, M. Lutz,
A.L. Spek, R.A. van Santen, D. Vogt, Dalton Trans. 2007, 46, 5372; d)
C. Müller, Z. Freixa, M. Lutz, A.L. Spek, D. Vogt, P.W.N.M. van
Leeuwen, Organometallics 2008, 27, 834; e) C. Müller, E.A. Pidko,
A.J.P.M. Staring, M. Lutz, A.L. Spek, R.A. van Santen, D. Vogt, Chem.
Eur. J. 2008, 14, 4899; f) C. Müller, E.A. Pidko, M. Lutz, A.L. Spek, D.
Vogt, Chem. Eur. J. 2008, 14, 8803; L.E.E. Broeckx, M. Lutz, D. Vogt,
C. Müller, Chem. Commun. 2011, 47, 2003; g) J.J.M. Weemers, J.
Wiecko, E. A. Pidko, M. Weber, M. Lutz, C. Müller, Chem. Eur. J. 2013,
19, 14458-14469; h) L. E. E. Broeckx, W. Delaunay, C. Latouche, M.
Lutz, A. Boucekkine, M. Hissler, C. Müller, Inorg. Chem. 2013, 52,
10738-10740; i) C. Müller, L. E. E. Broeckx, I. de Krom, J.J.M.
Weemers, Eur. J. Inorg. Chem. 2013, 187; j) L. E. E. Broeckx, S.
Güven, F. J. L. Heutz, M. Lutz, D. Vogt, C. Müller, Chem. Eur. J. 2013,
19, 13087-13098; k) C. Müller, J. A. W. Sklorz, I. de Krom, A. Loibl, M.
Habicht, M. Bruce, G. Pfeifer, J. Wiecko, Chem. Lett. 2014, 43, 1390-
1404; l) A. Loibl, I. de Krom, E.A. Pidko, M. Weber, J. Wiecko, C. Müller,
Chem. Commun. 2014, 50, 8842; m) J. A. W. Sklorz, C. Müller, Eur. J.
Inorg. Chem. 2016, 5, 595-606.
Acknowledgements
Financial support by Freie Universität Berlin and the Deutsche
Forschungsgemeinschaft (DFG) is gratefully acknowledged.
E.A.P. thanks the Ministry of Education and Science of the
Russian Federation (Project 11.1706.2017/4.6) for support. We
thank Mrs. M. Sc. Antonia Loibl for her help with creating part of
the graphical material.
Keywords: Phosphors • Heterocycles • Coordination Chemistry
• Ligands • DFT
[1]
(a) Phosphorus-Carbon Heterocyclic Chemistry: The Rise of a New
Domain (Ed.:F. Mathey), Pergamon: Palaiseau, 2001; b) Multiple
Bonds and Low Coordination in Phosphorus Chemistry (Eds.: M. Regitz,
O. J. Scherer), Thieme Verlag, Stuttgart, 1990; c) Phosphorus: The
Carbon Copy (Eds. K. B. Dillon, F. Mathey, J. F. Nixon), John Wiley &
Sons, 1998.
[8]
[9]
K. Nakajima, S. Takata, K. Sakata, Y. Nishibayashi, Angew. Chem. Int.
Ed. 2015, 54, 7597.
a) A. J. Ashe, III, J. Am. Chem. Soc., 1971, 93, 3293; b) A. J. Ashe, R.
R. Sharp, J. W. Tolan, J. Am. Chem. Soc. 1976, 98, 5451.
[2]
[3]
a) P. Le Floch, F. Mathey, Coord. Chem. Rev. 1998, 179-180, 771; b) N.
Mézailles, F. Mathey, P. Le Floch, Prog. Inorg. Chem. 2001, 455; c) L.
Weber, Angew. Chem., Int. Ed. 2002, 41, 563; d) P. Le Floch, Coord.
Chem. Rev. 2006, 250, 627; e) F. Mathey, P. Le Floch, Science of
Synthesis 2005, 5, 1097.
[10] N. Mézailles, L. Ricard, F. Mathey, P. Le Floch, Eur. J. Inorg. Chem.
1999, 2233.
[11] M. Doux, L. Ricard, F. Mathey, P. Le Floch, N. Mézailles, Eur. J. Inorg.
Chem. 2003, 687.
[12] M. Blug, O. Piechaczyk, M. Fustier, N. Mézailles, P. Le Floch, J. Org.
Chem. 2008, 73, 3258.
a) C. Müller, D. Vogt, Dalton Trans. 2007, 5505; b L. Kollár, G.
Keglevich, Chem. Rev. 2010, 110, 4257; c) Catalysis and Material
Science Applications, (Eds.: M. Peruzzini, L. Gonsalvi), Springer, 2011;
d) Phosphorus Ligand Effects in Homogeneous Catalysis: Design and
Synthesis (Eds.: P.C.J. Kamer, P.W.N.M van Leeuwen), Wiley-VCH,
2012; e) J. J. M. Weemers, W. N. P. van der Graaff, E. A. Pidko, M.
Lutz, C. Müller, Chem. Eur. J. 2013, 19, 8991-9004; f) S. Aguado-Ullate,
J. A. Baker, V. González-González, C. Müller, J. D. Hirst, J. J. Carbó,
Catal Sci. Tech. 2014, 4, 979-987; g) L. E. E. Broeckx, A. Bucci, C.
Zuccaccia, M. Lutz, A. Macchioni, C. Müller, Organometallics 2015, 34,
2943-2952.
[13] a) N. Avarvari, P. Le Floch, L. Ricard, F. Mathey, Organometallics 1997,
16, 4089; b) N. Avarvari, N. Mézailles, L. Ricard, P. Le Floch, F. Mathey,
Science, 1998, 280, 1587; c) N. Avarvari, N. Maigrot, L. Ricard, F.
Mathey, P. Le Floch, Chem. Eur. J. 1999, 5, 2109; d) U. Rhörig, N.
Mézailles, N. Maigrot, L. Ricard, F. Mathey, P. Le Floch, Eur. J. Inorg.
Chem. 2000, 2565; e) N. Mézailles, N. Maigrot, S. Hamon, L. Ricard, F.
Mathey, P. Le Floch, J. Org. Chem. 2001, 66, 1054.
[14] Y. Hatanaka, T. Hiyama, J. Org. Chem. 1988, 53, 918.
[15] a) P. Pellon, Y. Y. C. Yeung Lam Ko, P. Cosquer, J. Hamelin, R. Carrié,
Tetrahedron Lett. 1986, 27, 4299; b) M. Abbari, Y. Y. C. Yeung Lam Ko,
R. Carrié, Heteroatom Chem. 1991, 2, 439.
[4]
a) P. Roesch, J. Nitsch, M. Lutz, J. Wiecko, A. Steffen, C. Müller, Inorg.
Chem. 2014, 53, 9855-9859; b) J. Moussa, T. Cheminel, G.R. Freeman,
L.-M. Chamoreau, J.A.G. Williams, H. Amouri, Dalton Trans. 2014, 43,
8162; c) J. A. W. Sklorz, S. Hoof, N. Rades, N. De Rycke, L. Könczöl, D.
Szieberth, M. Weber, J. Wiecko, L. Nyulászi, M. Hissler, C. Müller,
Chem. Eur J. 2015, 21, 11096-11109; d) M. A. Shameem, A. Orthaber,
Chem. Eur. J. 2016, 22, 10718; e) X. Chen, Z. Li, F. Yanan, H.
Grützmacher, Eur. J. Inorg. Chem. 2016, 633-638.
[16] M. H. Habicht, F. Wossidlo, M. Weber, C. Müller, Chem. Eur. J. 2016,
22, 12877.
[17] a) S.M. Mansell, M. Green, R.J. Kilby, M. Murray, C.A. Russell, C. R.
Chemie 2013, 13, 1073-1081. b) J.G. Cordaro, D. Stein, H. Rüegger, H.
Grützmacher, Angew. Chem. Int. Ed. Engl. 2006, 45, 6159-6162.
[18] A. J. Arce, A. J. Deeming, Y. De Sanctis, A. M. García, J. Manzur, E.
Spodine, Organometallics 1994, 13, 3381. For the synthesis of 2-TMS-
phosphinine, the authors refer in their manuscript to a reference, which,
however, does not contain any synthetic procedure for the title-
compound.
[5]
[6]
a) C. W. Tsang, M. Yam and D. P. Gates, J. Am. Chem. Soc. 2003, 125,
1480; b) J. I. Bates, J. Dugal-Tessier, D. P. Gates, Dalton Trans. 2010,
39, 3151; c) B. W. Rawe, C. P. Chun, D. P. Gates, Chem. Sci. 2014, 5,
4928.
[19] a) M. Regitz, P. Binger, Angew. Chem. 1988, 100, 1541; b) B. Breit, J.
Mol. Catal. 1999, 143, 143.
a) B. Niaz, F. Iftikhar, M. K. Kindermann, P. G. Jones, J. Heinicke, Eur
J. Inorg. Chem. 2013, 4220; b) M. Ghalib, P. G. Jones, G. J. Palm, J. W.
Heinicke, RSC Adv. 2013, 3, 17726; c) M. Ghalib, L. Könczöl, L.
Nyulászi, P. G. Jones, G. J. Palm, J. W. Heinicke, Dalton Trans., 2014,
43, 51; d) J. W. Heinicke, M. Ghalib, C. Schulzke, P. G. Jones, L.
Könczöl, L. Nyulászi, Phosphorus, Sulfur, Silicon and Rel. El. 2015, 190,
[20] K. Afarinkia, V. Vinader, T. D. Nelson, G. H. Posner, Tetrahedron 1992,
48, 9111-9171.
[21] W. Rösch, M. Regitz, Angew. Chem. Int. Ed. Engl. 1984, 23, 900.
[22] W. Pieckle, M. Dines, J. Am. Chem. Soc. 1968, 90, 2318.
This article is protected by copyright. All rights reserved.

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Chemistry - A European Journal
FULL PAPER
[23] The 31P{1H} spectrum was measured without NOE-enhancement and
with a repetition time of t = 32.02 s.
[31] a) A. Savateev, Y. Vlasenko, N. Shtil, A. Kostyuk, Eur. J. Inorg. Chem.
2016, 628; b) P. Le Floch, F. Mathey, J. Chem. Soc., Chem. Commun.
1993, 1295.
[24] H. Kanter, K. Dimroth, Tetrahedron Lett. 1975, 8, 541.
[25] a) M. Shiotsuka, Y. Matsuda, Chem. Lett. 1994, 351; M. Shiotsuka, T.
Tanamachi, T. Urakawa, M. Munakata, Y. Matsuda, J. Supramol. Chem.
2002, 2, 211.
[32] W. Adock, G. L. Aldous, Tetrahedron Lett. 1978, 36, 3387.
[33] V. R. Ferro, S. Omar, R. H. González-Jonte, J. M. García de la Vega,
Heteroatom Chem. 2003, 14, 160.
[26] N. Mézailles, P. Le Floch, K. Waschbüsch, L. Ricard, F. Mathey, C. P.
Kubia, J. Organometal. Chem. 1997, 541, 277.
[34] See also: J. Waluk, H.-P. Klein, A. J. Ashe, J. Michl, Organometallics
1989, 8, 2804.
[27] Y. Mao, K.M.H. Lim, Y. Li, R. Ganguly, F. Mathey, Organometallics
2013, 32, 3562.
[35] Massimo Rigo, Ph.D. thesis, Freie Universität Berlin, 2017.
[36] C. Müller, E. A. Pidko, unpublished results.
[28] a) P. Le Floch, L. Ricard, F. Mathey, Bull. Soc. Chim. Fr. 1996, 133,
691; b) C. Müller, E.A. Pidko, M. Lutz, A.L. Spek, D. Vogt, Chem. Eur. J.
2008, 14, 8803.
[37] M. Nakagawa, M. Tonozuka, M. Obi, M. Kiuchi, T. Hino, Synthesis
1974, 7, 510
[38] G. Posner, K. Afarinkia, H. Dai, Organic Syntheses 1998, 9, 112.
[39] H. E. Gottlieb, V. Kotlyar, A. Nedelman, J. Org. Chem. 1997, 62, 7512.
[40] Bruker (2010). APEX2, SAINT, SADABS and XSHELL. Bruker AXS Inc.,
Madison, Wisconsin, USA.
[29] N. Mézailles, N. Avarvari, L. Ricard, F. Mathey, P. Le Floch, Inorg.
Chem. 1998, 37, 5513.]
[30] a) C. Elschenbroich, M. Nowotny, B. Metz, W. Massa, J. Graulich, K.
Biehler, W. Sauer, Angew. Chem. Int. Ed. 1991, 30, 547; b) C.
Elschenbroich, M. Nowotny, A. Behrendt, W. Massa, S. Wocadlo,
Angew. Chem. 1992, 104, 1388; c) C. Elschenbroich, M. Nowotny, A.
Behrendt, K. Harms, S. Wocadlo, J. Pebler, J. Am. Chem. Soc. 1994,
116, 6217; d) C. Elschenbroich, S. Voss, O. Schiemann, A. Lippek, K.
Harms, Organometallics 1998, 17, 4417.
[41] SHELX: G. M. Sheldrick, Acta Cryst. 2008, A64, 112
[42] Platon: A. L. Spek, Acta Cryst. 2009, D65, 148.
[43] M.J. Frisch et al. Gaussian 09, Revision D.01, Gaussian, Inc.,
Wallingford CT, 2013.
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10.1002/chem.201704539
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2-(Trimethylsilyl)-λ3-
phosphinine can easily be
prepared by a [4+2]
cycloaddition between 2-
pyrone and (CH3)3Si-C≡P.
Protodesilylation yields the
parent phosphine C5H5P.
The coordination
Marija H. Habicht,
Friedrich Wossidlo, Tobias
Bens, Evgeny A. Pidko, and
Christian Müller*
Page No. – Page No.
2-(Trimethylsilyl)-λ3-
Phosphinine: Synthesis,
Coordination Chemistry
and Reactivity
chemistry was
investigated, while DFT
calculations give insight
into the electronic
properties of the
phosphorus heterocycles.
This article is protected by copyright. All rights reserved.