3H-Phosphaallenes Revisited: Facile Synthesis by Hydroalumination of Alkynylphosphines and β-Elimination, Stability and Trapping of Transient Species by Coordination to Transition Metal Atoms

Article abstract of DOI:10.1002/chem.201806334

A facile method for the efficient synthesis of 3H-phosphaallenes, R?P=C=C(H)?R′, is presented, which comprises treatment of dialkynylphosphines with dialkylaluminium hydrides (hydroalumination) and elimination of aluminium alkynides from intermediate alke

Full text of DOI:10.1002/chem.201806334

A Journal of
Accepted Article
Title: 3H-Phosphaallenes Revisited: Facile Synthesis via
Hydroalumination of Alkynylphosphines and β-Elimination,
Stability and Trapping of Transient Species by Coordination to
Transition Metal Atoms
Authors: Werner Uhl, Hans Klöcker, Jonas Tendyck, Lukas Keweloh,
and Alexander Hepp
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FULL PAPER
DOI: 10.1002/chem.200((will be filled in by the editorial staff))
3H-Phosphaallenes Revisited: Facile Synthesis via Hydroalumination of Al-
kynylphosphines and β-Elimination, Stability and Trapping of Transient Species by
Coordination to Transition Metal Atoms
Hans Klöcker,[a] Jonas C. Tendyck,[a] Lukas Keweloh,[a] Alexander Hepp,[a] and Werner Uhl*[a]
Abstract: A facile method for the effi- groups). Only supermesityl compounds P=C bond resulted with platinum. De-
cient synthesis of 3H-phosphaallenes, are persistent at room temperature in so- composition of the mesityl derivative
R-P=C=C(H)-R’, is presented, which lution. This simple method starting with yielded an unprecedented product,
comprises
treatment
of
dial- easily accessible dialkynylphosphines which may be formed by 1,3-H shift to
kynylphosphines with dialkylaluminium and commercially available aluminium the P atom, hydrophosphination of the
hydrides (hydroalumination) and elimi- hydrides (HAlEt2, HAliBu2) allows the P=C bond of a second phosphaallene
nation of aluminium alkynides from in- generation of transient species, which and formation of a P-P bond.
termediate alkenyl-alkynylphosphines. were trapped by coordination to transi-
The stability of the phosphaallenes de- tion metals. The η1-coordination via a P-
pends on steric shielding by the substit- W bond was observed for tungsten,
uents at phosphorus (aryl or CH(SiMe3)2 while the side-on coordination via the
the metal center.[17c] Reactions with Main Group elements or their
Introduction
compounds, such as sulfur, hydrogen peroxide, n-butyllithium, protic
reagents or dichlorcarbene, are rare.[6,8,11b,12b,19]
Phosphaallenes, R-P=C=C(R’)R’’ (1; Scheme 1), form a fascinating
class of compounds with cumulated P=C and C=C double bonds.[1]
They are highly reactive, kinetically labile species and isolable only
with bulky substituents. They have been obtained on various routes
such as the reaction of ketenes with silylphosphinides or comparable
reagents (Peterson olefination),[2-6] the reactions of ketenes with phos-
phorus ylides (Wittig type reactions),[5,7] by dehydrohalogenation of
1-chlorovinylphosphines (transient species only),[8,9] rearrangement
reactions starting with alkynylphosphines,[3,8,10-11] ring opening of a
phosphirane,[12] from a λ5-phosphaallene[13] and further specialized
methods. Several uncoordinated, free phosphaallenes have been au-
thenticated by crystal structure determination;[7,14,15] quantum chemi-
cal calculations gave a comprehensive insight into their structure,
bonding and charge distribution. The central C atom was found as the
preferred position for the attack of protons.[1,14a,16] Studies into the
chemical reactivity of these compounds are relatively limited. In the
few known transition metal complexes the phosphaallenes are coor-
dinated via the P atoms in an η1-fashion.[1,17] The side on coordination
via the P=C bond (η2) has been postulated based on NMR and IR
data[18] and was observed for a phosphaallene which was generated at
Scheme 1. Phosphaallenes, an Al/P-based FLP [R = CH(SiMe3)2] and the trapping prod-
uct of a phosphaallene.
Recently we found facile access to transient phosphaallenes by
hydroalumination of di(tert-butylalkynyl)- or amino-tert-butyl-
alkynylphosphines.[20-22] The addition of an Al-H bond to a C≡C triple
bond resulted in the formation of geminal Al/P compounds (2) in
which the Lewis acidic Al atoms approach the remaining alkynyl or
amino groups. These intramolecular interactions facilitate 1,2-elimi-
nation of aluminium alkynides or amides and formation of 3H-phos-
phaallenes with a P=C=C(H)-R’ group and a H atom in β-position to
phosphorus. The highly exothermic formation of dimeric dialkylalu-
minium alkynides was identified by quantum chemical calculations
(Lammertsma group) as the main driving force.[20] Careful studies
into the kinetics of such reactions have been published only re-
cently.[21] Bulky CH(SiMe3)2 groups bound to aluminium (2; Scheme
1) hinder the contact beteween the Lewis centers and help to stabilize
such Al/P compounds[21] which represent nice examples of function-
alized Al/P-based frustrated Lewis pairs.[23] The eliminated Al al-
kynides R2Al-C≡C-R’ (R = CH(SiMe3)2; R’ = CMe3, Ph) are mono-
meric in these cases,[24] and the missing dimerization energy contrib-
utes to the slow degradation of the addition products. The obtained
[a]
Dr. H. Klöcker, J. C. Tendyck, Dr. L. Keweloh, Dr. A. Hepp, Prof. Dr.
W. Uhl
Institut für Anorganische und Analytische Chemie
Westfälische Wilhelms-Universität Münster,
Corrensstrasse 30, 48149 Münster, Germany
Fax: (+)49 251 8336660
e-mail: uhlw@uni-muenster.de
1
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10.1002/chem.201806334
Chemistry - A European Journal
13C NMR resonances in narrow ranges at δ = 80 (P-C≡C) and 115
ppm (P-C≡C) with the largest deviation from these average values for
the phenylethynylphosphine 11. The stretching vibrations of the triple
bonds gave two IR absorptions at about 2200 and 2150 cm–1. We de-
termined several structures of these dialkynylphosphines, that one of
the supermesityl compound 10 is depicted in Figure 1. The P-C(aryl)
bond lengths (185 pm on average) are expectedly longer than the dis-
tances between the P atoms and the sp-hybridized alkynyl C atoms
(177 pm). The P-C≡C-C groups deviate slightly from linearity with
the largest deviation at the α-C atom bound to phosphorus (P-C≡C
169°; C≡C-C 177°).
phenyl or mesityl substituted phosphaallenes were unstable and
started to decompose before the elimination reaction was finished, but
were identified by NMR spectroscopy. In other cases[20] the 3H-phos-
phaallenes could not be identified as intermediates. As shown by DFT
calculations, they were immediately trapped by the hydroalumination
products which coordinated the P=C=C groups in a typical FLP fash-
ion to afford five-membered AlC2P2 heterocycles (3; Scheme 1).[20,21]
Previously the groups of Appel, Märkl and Yoshifuji isolated persis-
tent 3H-phosphaallenes, which were kinetically protected by bulky
tri(tert-butyl)phenyl groups.[5,10,15] Methods for their generation com-
prise the treatment of Mes*P(H)Cl with alkyllithium reagents and the
base initiated 1,3-shift of H atoms of alkynylphosphines, Aryl-P(H)-
C≡C-R’.[10,11b] In extension of our previous work we wanted to gen-
erate persistent or at least isolable phosphaallenes by hydroalumina-
tion or 1,3-H shift. Variation of the bulk of the substituents attached
to phosphorus should allow a systematic insight into the accessibility,
stability and lifetime of such compounds and their applicability in
secondary reactions. The development of efficient methods for the
fast and selective formation of 3H-phosphaallenes, including alkyl or
sterically less shielded derivatives, is indispensable for their wide ap-
plication in secondary transformations.
Scheme 3. Synthesis of alkynylphosphines ((i): -LiCl: (ii): +Li[BHEt3], -BEt3, -LiCl).
Results and Discussion
Starting materials
The phosphaallenes were obtained on two different routes which re-
quired two distinct classes of starting materials, namely dial-
kynylphosphines, R-P(C≡C-R´)2 (8 to 16; Scheme 2) and aryl-mono-
alkynylphosphines, Aryl-P(H)-C≡C-CMe3 (20 to 22; Scheme 3). The
steric shielding of these compounds is easily modified by the bulk of
the groups R and R´ at phosphorus or the alkynyl substituents. We
applied mesityl (Mes, 2,4,6-Me3C6H2), triisopropylphenyl (Trip,
2,4,6-iPr3C6H2) and supermesityl (Mes*, 2,4,6-tBu3C6H2) groups at
phosphorus and tBu, cyclohexenyl, cyclohexyl, 1-adamantyl and phe-
nyl groups at the β-C atoms. The dialkynylphosphines 15 and 16 with
bulky CH(SiMe3)2 groups attached to phosphorus should help to syn-
thesize the first alkyl substituted phosphaallenes and to study the in-
fluence of such groups on their generation and stability. All syntheses
started with easily available dichlorides R-PCl2, which were obtained
according to known procedures by treatment of PCl3 with the corre-
sponding diarylmagnesium compounds or LiCH(SiMe3)2.
Figure 1. Molecular structure and numbering scheme of 10; similar structures for 9, 12
to 16; displacement ellipsoids are drawn at the 40% level. H atoms have been omitted.
Selected average bond lengths [pm] and angles [°]: C≡C 120.0, P-C(alkyne) 176.7, P-
C(aryl) 185.0, P-C≡C 168.7, C≡C-C 176.9.
Treatment of the dichlorides with one equivalent of lithium tert-
butylethynide afforded chloro-monoalkynylphosphines, Aryl-P(Cl)-
C≡C-tBu (17[22] to 19; Scheme 3), which were contaminated with
small quantities (~10%) of the dichloro and dialkynyl species. 18 was
only generated in-situ and directly used for the synthesis of phosphine
21. The mesityl compound 17 was obtained in a pure form by recrys-
tallization from n-hexane and sublimation in vacuum (60 °C, 10-3
mbar). The less volatile supermesityl compounds [Mes*-PCl2 and
Mes*-P(Cl)-C≡C-tBu] tend to decompose slightly above the sublima-
tion temperature. Careful consideration of conditions (90 °C, 10-3
mbar) is required, and only small quantities of pure 19 should be gen-
erated to avoid long sublimation times. Reaction of the chloro-al-
kynylphosphines with Li[BHMe3] afforded the phosphines Aryl-
P(H)-C≡C-tBu (20 to 22; Scheme 3). The mesityl compound 20 has
been reported previously.[23a] Compound 21 was only generated in an
NMR experiment and characterized by NMR spectroscopy. It con-
tained several impurities, two were identified as the dial-
kynylphosphine 8 and triisopropylbenzene. It was directly applied in
rearrangement reactions. Purification of compound 22 by recrystalli-
sation required the complete removal of the borane by-product in vac-
uum. 22 is most conveniently generated in a 200 mg scale and was
obtained previously on another route by treatment of Mes*-P(H)Cl
with lithium alkynide.[10a] Compounds 20 to 22 show the expected
singlets in the 31P NMR spectra at δ = -118.8, -124.1 and -102.1 ppm.
The ethynyl groups gave 13C NMR resonances at about δ = 75 (P-
C≡C) and 113 ppm (P-C≡C). The molecular structures of Mes*-
P(Cl)-C≡C-tBu (19) and Mes*-P(H)-C≡C-tBu (22; Figures 2 and 3)
reveal the expected pyramidal surrounding of the P atoms. The bond
lengths correspond to standard values [P1-Cl1 210.3(1), P-C(≡C)
Scheme 2. Synthesis of dialkynylphosphines (1-Ad = 1-adamantyl).
Reaction of R-PCl2 with two equivalents of in situ generated lith-
ium alkynides (Scheme 2) afforded dialkynylphosphines 8 to 16 in
yields of 51 (9) to 99% (15). We reported recently on the synthesis
and characterisation of the mesityl derivative 8.[20] The 31P NMR res-
onances were observed for the arylphosphines (8 to 14) between δ =
-71.8 (13; R = Mes*) and -87.6 ppm (9; R = Trip), for the al-
kylphosphines 15 and 16 at δ = -64.1 ppm. The ethynyl groups show
2
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10.1002/chem.201806334
Chemistry - A European Journal
product similar to 2 allowed its isolation (see Experimental Part) and
determination of its crystal structure.[26] Phosphaallene 25 is inert to-
wards air and water.
176.4(av) and C≡C 120.0(av) pm], and the alkynyl groups deviate
only slightly from linearity (P-C≡C 168°; C≡C-C 177°). The P atoms
represent stereogenic centers with both enantiomers generated by the
symmetry operation of the space group.
t
Scheme 4. Synthesis of 3H-phosphaallenes by hydroalumination [R’’ = Et, iBu, Bu,
CH(SiMe3)2].
Figure 2. Molecular structure and numbering scheme of the chlorophosphine 19; dis-
placement ellipsoids are drawn at the 40% level. H atoms have been omitted. Selected
bond lengths [pm] and angles [°]: C≡C 119.9(2), P-C(alkyne) 175.8(1), P-C(aryl)
184.3(1), P-C≡C 164.4(1), C≡C-C 176.6(1).
The alkyl-substituted phosphaallenes 30 and 31 were obtained on
a similar route starting with the dialkynylphosphines 15 and 16
(Scheme 4). While 30 with a tert-butyl group in β-position decom-
posed slowly in solution, the adamantyl derivative 31 was stable in
dilute solutions at room temperature over weeks. It decomposes upon
concentration, which prevented its isolation by crystallisation. We
also applied a C(SiMe3)3 phosphine, but the high steric shielding pre-
vented hydroalumination. 31 and 32 represent the first alkyl substi-
tuted phosphaallenes and confirm the capability of this method for the
generation of a wide variety of such compounds.
Reactions of Mes*-P(H)Cl with lithium alkynides were reported
to afford 3H-phosphaallenes, Mes*-P=C=C(H)-R’, while the corre-
sponding Grignard reagents yielded alkynylphosphines, Mes*-P(H)-
C≡C-R’, under similar conditions.[10,11b] The spontaneous rearrange-
ment by 1,3-H shift in the first case was ascribed to the higher basicity
of organolithium reagents. We applied nitrogen bases and treated the
P-H compounds 20 to 22 with NEt3, pyridine, dimethylamino-
pyridine, diazobicyclooctane (DABCO) etc., but did not observe a
transformation at room temperature. Fast rearrangement occurred,
however, when solutions of 20 to 22 in n-pentane were treated with
10 mol% of diazobicycloundecene (DBU) (Scheme 5). After about
two hours the starting compounds were completely consumed, and
the phosphaallenes were identified by their 31P NMR resonances [ =
56.0 ppm (23, R = Mes); 56.0 ppm (24, R = Trip); 74.1 ppm (25, R =
Mes*[10])]. The formation of phosphaallenes by treatment of phos-
phines with DBU has previously been postulated or derived from
spectroscopic findings.[14b,27,28] The basicities of DABCO and DBU
are almost identical. The higher reactivity of DBU may depend on the
1,3-position of two N atoms. Recrystallisation of 25 from 1,2-
difluorobenzene afforded only few crystals. The base seems to hinder
crystallisation. As was shown in a small-scale experiment, DBU can
be removed by column chromatography (SiO2; n-hexane as eluent) to
afford 25 quantitatively.
Figure 3. Molecular structure and numbering scheme of phosphine 22; displacement el-
lipsoids are drawn at the 40% level. H atoms have been omitted. Selected bond lengths
[pm] and angles [°] (average values): C≡C 120.1, P-C(alkyne) 176.7, P-C(aryl) 185.4, P-
C≡C 170.1, C≡C-C 176.5.
3H-Phosphaallenes
Hydroalumination of the dialkynylphosphines 8 to 16 with different
dialkylaluminium hydrides and elimination of dialkylaluminium al-
kynides afforded the phosphaallenes 23 to 31 (Scheme 4). The re-
leased alkynides were identified by NMR spectroscopy.[24,25] The ste-
rically less shielded mesityl compound 8 required the sterically en-
cumbered hydride H-Al[CH(SiMe3)2]2, otherwise the intermediately
formed phosphaallene 23 reacted with the hydroalumination product
to afford a five-membered P2C2Al-heterocycle analogous to 3.[20,21]
The hydroalumination product 2 was detected as an intermediate.[21]
The synthesis of 23[21] was optimized, and for the first time we were
able to trap the highly reactive compound in secondary reactions (see
below). Sterically better shielded Trip-P(-C≡C-tBu)2 9 reacted with
H-Al[CH(SiMe3)2]2 to yield an addition product similar to 2 in the
first step [δ(31P) = -55.2 ppm; δ(1H) = 0.12 ppm (AlCH), 6.46 ppm
3
(C=CH), JPH = 37.5 Hz]. It is unstable in solution and decomposes
[24]
by elimination of [(Me3Si)2CH]2Al-C≡C-CMe3 and formation of
Trip-P=C=C(H)-tBu (24). In an optimized procedure, 24 was ob-
tained from the dialkynylphosphine and commercially available H-
AliBu2. 24 was detected in solution at ambient temperature for many
hours, but slow decomposition prevented its purification and isola-
tion. Its constitution was confirmed by complete assignment of the
NMR spectra and coordination to a transition metal (see below). All
supermesityl derivatives are persistent in solution at room tempera-
ture and were synthesized by treatment of the dialkynylphosphines
with H-AlEt2. H-AliBu2 gave similar results. We did not detect any
intermediate. Warming of the mixtures to room temperature and chro-
matographic work-up over humid silica gel resulted in the hydrolytic
degradation of the aluminium by-products and the isolation of the per-
sistent phosphaallenes Mes*-P=C=C(H)-R’ (25 to 29) as colourless
solids or oils in about 80% yield. The synthesis of 25 on another route
has been reported previously (see below), the more convenient pro-
cedure given here allows its simple synthesis in a five-gram scale in
a highly selective reaction and will stimulate its application in sec-
ondary transformations. H-Al[CH(SiMe3)2]2 gave the same reaction.
The relatively slow degradation of the intermediate hydroalumination
Scheme 5. Synthesis of 3H-phosphaallenes in the presence of DBU.
Phosphaallenes 23 and 24 decompose at room temperature in so-
lution, and these reactions seem to be catalysed by the base in accord-
ance with observations on related systems.[28,29] Compared to the syn-
theses in the presence of DBU, the phosphaallenes 23 and 24 obtained
by alkynide elimination show a considerably longer lifetime (about a
factor of two). Because this route seemed not to be suitable to gener-
ate 24 in a pure form or to trap it in secondary reactions, we abstained
from the synthesis in a preparative scale. The base initiated 1,3-shift
3
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10.1002/chem.201806334
Chemistry - A European Journal
of H atoms led to the formation of 3H-phosphaallenes, but important
disadvantages are the difficult access to the pure starting compounds
Aryl-P(H)-C≡C-tBu, the difficult removal of the non-volatile amine
under mild conditions, the relatively fast decomposition of 23 and 24,
which is catalysed by DBU, and the insufficient crystallisation of the
persistent compound 25.
chemical shifts of the vinylic H atoms (δ = 5.7 ppm) are almost un-
changed, but the JPH coupling constants increase to about 45 Hz
3
which may depend on the increased coordination number at phospho-
rus. The 13C NMR resonances of the central C atoms of the PCC(H)
groups at about  = 236 ppm confirm the intact phosphaallene struc-
tures. The 1JPC coupling constants, in contrast, are with 88 Hz on av-
Compounds 23 to 31 show 31P NMR resonances in the expected
range between δ = +56 (23 and 24, R = Mes, Trip) and about +74 ppm
1
erage comparably large. The W-P coupling constants JPW are in a
narrow range between 260 (35) to 276 Hz (34) and in accordance with
the presence of P-W bonds. The IR spectra of the complexes are sim-
ilar and showed absorptions for the CO stretching vibrations between
2070 and 1920 cm–1. There is no significant difference to complexes
with typical phosphine ligands such as triphenylphosphine.[9,30] These
complexes are thermally quite stable, show melting points between
93 to 157 °C and can be stored in solution at room temperature over
weeks without decomposition.
1
[R = Mes*, CH(SiMe3)2]. The vinylic H atoms resonate in the H
NMR spectra at about δ = 5.7 ppm with 3JPH coupling constants of 26
Hz. Exceptions were found for the chemical shifts of 26 and 27 (δ =
6.5 ppm) in which sp2-hybridized C atoms are in geminal positions to
the respective H atoms. The resonances of the inner C atoms of the
P=C=C groups in the 13C NMR spectra are indicative for the phos-
phaallene structure and show strong low field shifts with values of
about δ = 240 ppm (1JPC = 29 Hz). The β-C atoms of the allene moi-
eties (P=C=C) resonate at δ = 122 ppm with 2JPC coupling constants
of about 12 Hz. There is no significant spectroscopic difference be-
tween the Mes* and CH(SiMe3)2 substituted phosphaallenes.
The molecular structures of the colourless compounds 25 to 28
(Figure 4) reveal the expected P=C=C motif with P=C (163.4 pm) and
C=C distances (131.6 pm) in the typical ranges. In accordance with
results reported in the literature[7,14,15] the P=C=C groups deviate
slightly from linearity with P1-C1-C2 angles of 171° on average. The
C4-P1-C1 angles including the ipso-C atoms of the supermesityl
groups are 103°. With exception of the cyclohexyl compound 28 the
aromatic rings of the supermesityl groups show the usual deviation
Scheme 6. Synthesis of 3H-phosphaallene complexes of W(CO)5.
The W atoms of 32 to 36 have slightly distorted octahedral coor-
dination spheres and are bonded to the phosphaallenes in a η1-fashion
with W-P distances in a narrow range of 249 pm (Figure 5). The
groups P1-C1-C2 (171°) deviate slightly from linearity and show the
characteristic lengths of P=C (163 pm on average) and C=C bonds
(131 pm). The C-P=C angle of 34 is almost identical to that one of
the starting compound 25 (103°), larger values were observed for the
other complexes (112° on average). The angles C-P-W (including the
C atom of R) are almost identical (125°) in 32, 33, 35 and 36, while a
relatively large angle resulted for 34 bearing the bulky Mes* group
(138.8(3)°). The sums of the angles at the P atoms are close to 360°.
The aryl groups show an increasing distortion with increasing bulk of
the substituents, the ipso-C atom of 32 is 1.5 pm and that one of 34
12.5 pm above the plane of the remaining five C atoms of the aromatic
rings. Most of the complexes 32 to 36 are based on unstable phos-
phaallenes, which are trapped and stabilized by coordination to a tran-
sition metal atom. They allow the unambiguous identification of the
phosphaallenes and confirm their constitution.
from planarity with the ipso-C atoms 13 pm above the plane of the
[15]
remaining five C atoms. With Mes*-P=C=CH2
and the corre-
sponding compound bearing a cyclopropyl ring instead of a H
atom[14e] the structures of only two 3H-phosphaallenes are reported in
the literature; the structures of the text book compounds 25 and 26
were obtained more than 30 years after first reports on their synthe-
ses.[10,15]
Figure 4. Molecular structure and numbering scheme of phosphaallene 25; similar struc-
tures for 26 to 28; displacement ellipsoids are drawn at the 40% level. H atoms (with the
exception of β-H) have been omitted. Selected average bond lengths [pm] and angles [°]:
P=C 163.4, C=C 131.6, P=C=C 170.7, C-P=C 102.8.
Coordination behavior of the 3H-phosphaallenes 32 to 36
Only few structurally authenticated transition metal complexes of
phosphaallenes are reported in the literature.[9,17] We hoped to trap
and stabilize transient 3H-phosphaallenes by coordination to W(CO)5
fragments and included in these studies the persistent supermesit-
ylphosphaallene 25, which has so far not been applied as a ligand in
coordination chemistry. The unstable phosphaallenes 23, 24, 30 and
31 were generated by hydroalumination as described above, the re-
sulting solutions were stirred at room temperature and treated with an
excess of in-situ generated (THF)W(CO)5 (Scheme 6). Column chro-
matography over untreated SiO2 resulted in hydrolysis of the or-
ganoaluminium by-products, and the complexes were isolated from
the eluates (n-hexane as eluent) in yields of 28 to 79%. The super-
mesitylphosphaallene complex 34 was obtained by treatment of 25
with (THF)W(CO)5 at room temperature and isolated after recrystal-
lization in 73% yield (Scheme 6). The complexes 32 to 36 show sin-
glets in the 31P{1H} NMR spectra at about  = +39 (R = Mes, Trip),
+50.7 (R = Mes*) and 56.7 ppm [R = CH(SiMe3)2] which are shifted
to a higher field by 17 to 27 ppm compared to phosphaallenes. The
Figure 5. Molecular structure and numbering scheme of phosphaallene-tungsten complex
32; similar structures for 33 to 36; displacement ellipsoids are drawn at the 40% level. H
atoms (with the exception of β-H) have been omitted. Selected average bond lengths [pm]
and angles [°]: P-W 248.8, P=C 162.8, C=C 130.5, P=C=C 170.6, C-P=C 109.9.
In addition we treated the Mes and Mes* phosphaallenes 23 and
25 with (Ph3P)2Pt(H2C=CH2) (Scheme 7). 23 was generated in situ as
described above and reacted with the Pt complex at room temperature.
Crystallisation of the crude product from 1,2-difluorobenzene (-
45 °C) afforded colorless crystals of the Pt compound 37 in 32% yield.
37 decomposes only above 214 °C. The complex of the Mes* phos-
phaallene was obtained from 25 and equimolar quantities of the Pt
starting compound in toluene at 0 °C. Recrystallization from CH2Cl2
(-30 °C) afforded a yellowish powder of 38 in 63% yield. Molecular
4
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10.1002/chem.201806334
Chemistry - A European Journal
structures (Figure 6) revealed an interesting coordination mode with
the phosphaallenes side-on coordinated to the Pt atoms via the P=C
bonds. Three-membered PtPC heterocycles resulted which had an ex-
ocyclic C=C bond [132.6(3) and 134.5(7) pm] and the cis-arrange-
ment of Pt and vinylic H atoms. The endocyclic Pt-C and Pt-P dis-
tances (208.2 and 234.4 pm on average) correspond to standard values,
the latter ones are longer by about 3 to 5 pm compared to the distances
to the PPh3 ligands. The P-C bond lengths in the rings [176.7(2) and
172.4(7) pm] are expectedly longer than the P=C bond in 25 (163.4
pm), but shorter than the P-C distances to the aryl groups [186.0(2)
and 188.2(4) pm]. The smallest endocyclic angles are found at the Pt
(about 46°), the largest ones at the C atoms (about 75°). The Pt atoms
have distorted planar coordination spheres. An average deviation of
the PPh3 P atoms from the Pt1C1P1 plane of 27 pm was observed for
37, while in 38 a large deviation of 74 pm resulted for P2 which is
trans to P1 in the ring. The endocyclic P atoms have pyramidal sur-
roundings with sums of the angles of 279.7 (37) and 299.2° (38),
which reflect the flattening of the sterically most encumbered com-
pound. The latter value results almost exclusively from the angle
C4(aryl)-P1-Pt1 [129.7(1) versus 111.45(7)° in 37] and reflects steric
repulsion between the neighboring Mes* and vinylic tBu groups. The
angles P1-C1-C2 (146° on average) are smaller than that one of 25.
Decomposition
Decomposition of phosphaallenes afforded different products by di-
merization via their P=C (head-to-tail[5a,15]
or C=C
)
bonds.[14c,14e,15,28,29]. Particularly interesting was the base catalyzed
formation of 1,4-diphosphafulvenes[14d,29] with unsaturated five-
membered P2C3-heterocycles by [3+2]-cycloaddition. They had
endo- and exocyclic C=C bonds and were isolated as 1:1 mixtures of
E/Z-isomers, which could not be separated by crystallization or chro-
matography. NMR characterization allowed their identification. The
31P NMR resonances showed characteristic AB patterns and were ob-
served at a low field (δ = 52 and 24 ppm, 2JPP = 22 Hz). Recently, we
reported on the kinetics of the decomposition of mesit-
ylphosphaallene 23, but the reaction was relatively unselective, and
we had not been able to enrich a component for an appropriate char-
acterization.[21] Under optimized conditions, we treated di(tert-butyl-
alkynyl)phosphine 8 in n-hexane at room temperature with a solution
of H-Al[CH(SiMe3)2]2 in the same solvent and stirred the mixture for
one week. Removal of the solvent afforded a colourless oil in a rela-
tively high purity. The mass spectrum showed the mass of a dimeric
formula unit of 23. Similar to the diphosphafulvenes the oil showed
two sets of doublets in the 31P{1H} NMR spectrum for two isomers
at δ = -52.5 and -73.0 ppm (JPP = 119.0 Hz) and δ = -47.2 and -69.9
ppm (JPP = 126.3 Hz; ratio 3:2). These values differ significantly from
those of diphosphafulvenes and indicate an unprecedented reaction.
13C NMR spectra revealed the characteristic resonances of alkenyl
and alkynyl groups. 2D NMR spectra allowed the assignment of the
molecular structures of both diastereomers (39a and 39b; Scheme 8).
A diphosphine is formed with a central P-P bond, one P atom binds
to an alkynyl group, the second one is attached to a vinyl substituent.
39 is formally formed by 1,3-shift of a H atom to phosphorus and
hydrophosphination of a second phosphaallene molecule. This obser-
vation reflects a possible reactivity of the β-H atom of 3H-phos-
phaaallenes. The Trip compound 24 showed a similar behaviour in an
NMR experiment and dimerized at room temperature to yield the di-
asteromeric diphosphines 40a and 40b (31P{1H} NMR: δ = -47.4 and
-69.9 ppm (JPP = 138.8 Hz); δ = -53.0 and -72.0 ppm (JPP = 118.8 Hz).
We were not able to enrich the dimer.
Scheme 7. Synthesis of the Pt complexes 37 and 38.
Figure 6. Molecular structure and numbering scheme of phosphaallene-platinum com-
plex 37; similar structure for 38; displacement ellipsoids are drawn at the 40% level. H
atoms (with the exception of β-H) have been omitted. Selected average bond lengths [pm]
and angles [°]: P-Pt 234.4, P-C(1)1174.6, C=C 133.6, P-C=C 146.4, P-Pt-C 46.0, P-C-Pt
74.9, Pt-P-C 59.2.
The reduced P-C bond order resulted in significantly changed
NMR data. The 31P NMR resonances of the phosphaallene ligands (
= -128.7/-91.0 ppm) show a strong high-field shift compared to 23
and 25 or the corresponding W complexes (32 to 37). 13C NMR res-
onances at about  = 240 ppm of the inner C atoms of the P=C=C
units disappeared and two signals at about  = 137 ppm confirmed the
presence of a C=C bond. An intriguing finding is a large 1JPC coupling
constant to the ipso-C atom of the Mes* group in 38 (123.0 Hz com-
pared to 34.2 to 64.0 Hz in phosphaallenes or their complexes), which
may reflect an increased s-character in the P-C bond in accordance
with the large C4(aryl)-P1-C1 angle (see above). Pt satellites indicate
the coordination to platinum. The planar coordination sphere of the
Pt atoms is confirmed by different resonances for the PPh3 ligands
and the coupling constants 2JPP to the P atoms of the phosphaallenes,
which are about 50 Hz for the trans- and about 12 Hz for the cis-
coupling.
Scheme 8. Thermal decomposition of phosphaallenes. [(i) R = Mes; W(CO)5THF, -THF].
For isolation and further characterization of the decomposition
product, we treated the mixture of 39 and the aluminium alkynide
with W(CO)5(THF). Column chromatography over SiO2 destroyed
the organoaluminium component and gave a yellow oil, which af-
forded yellow crystals of the W complex 41 in 58% yield (based on
dialkynylphosphine) after crystallization from n-hexane at -45 °C.
Two diastereomers were identified by NMR spectroscopy similar to
39, but the ratio changed from 3 : 2 to 5 : 1. Crystal structure deter-
mination (Figure 7) confirmed the constitution of the diphosphine 39.
One P atom of a central P-P bond [225.4(1) pm] is bound to a mesityl
and an alkynyl group [119.1(4) pm; P1], the second one (P2) to a me-
sityl and an alkenyl group [132.2(4) pm]. P1 is coordinated to the W
atom (δ = -30.7 ppm; 1JWP = 218.4 Hz; 1JPP = 272.1 Hz), which may
5
This article is protected by copyright. All rights reserved.

10.1002/chem.201806334
Chemistry - A European Journal
1,2-difluorobenzene with molecular sieves) using standard Schlenk tech-
niques. NMR spectra were recorded in benzene-d6 at ambient probe tempera-
ture using the following Bruker instruments: Avance I (1H, 400.13; 13C, 100.61
MHz), Avance III (1H, 400.03; 13C, 100.59 MHz) and referenced internally to
residual solvent resonances (chemical shift data in δ). 13C NMR spectra were
all proton-decoupled. Elemental analyses were determined by the microana-
lytic laboratory of the Westfälische Wilhelms Universität Münster. IR spectra
were recorded as paraffin mull between KBr plates or as KBr pellets on a Shi-
madzu Prestige 21 spectrometer, EI mass spectra on a Varian mass spectrom-
eter (only the most intense peak of the correct isotopic pattern). MesPCl2 4 and
Cl2P-CH(SiMe3)2 7 were obtained according to literature procedures[31,32]; the
syntheses and characterisation of the dichlorophosphines, ArylPCl2 (Aryl =
Trip, Mes*), have been reported previously.[33,34] Modified procedures are
given below. The synthesis of the dialkynylphosphine 8 and mesity-tert-bu-
tylethynylphosphine 20 have been reported.[20,23a] H-AlEt2 and H-AliBu2 were
generously provided by Chemtura, H-Al[CHSiMe3)2]2 and H-AltBu2 were ob-
tained according to literature procedures.[35]
be caused by its better steric accessibility. No W-P coupling was de-
tected for P2 (δ = -19.8 ppm). The structure depicted in Figure 7 rep-
resents the R,S-isomer of the diphosphine, with its enantiomer formed
by the symmetry operation of the space group. The NMR spectra of
the free and the coordinated diphosphine are very similar. The cou-
pling constants to the W bound P atom increase, which reflects the
increased s-character in the respective bonds.
Synthesis of Aryl-PCl2 (Aryl = Trip, Mes*); general procedure: Magne-
sium (20 to 50 mmol; 20% excess) was suspended in a solution of the corre-
sponding bromoaryl compound in THF (50 mL). The mixture was heated un-
der reflux for 1 h. 1,4-Dioxane (5 eq. for 5, equimolar quantities for 6) was
added at room temperature, and the resulting suspension was stirred for 2 h.
The solid was allowed to settle over night. The supernatant solution was re-
moved by a pipette and added to a cooled (-78 °C) solution of PCl3 (excess: 5
eq. for 5, 2 eq. for 6) in THF (20 mL). The mixture was warmed to room
temperature overnight. All volatiles were removed in vacuum, and the residue
was treated with n-pentane (50 mL). After filtration and removal of the solvent
in vacuum the dichlorides were isolated as colourless or yellowish oils in
~95% purity.
Figure 7. Molecular structure and numbering scheme of the diphosphine-tungsten com-
plex 41; displacement ellipsoids are drawn at the 40% level. H atoms (except H5) have
been omitted. Selected average bond lengths [pm] and angles [°]: P1-W1 254.8(1), P1-
P2 225.4(1), C1-C2 119.1(4), C5-C6 132.2(4), P1-P2-C5 101.6(1), P2-P1-C1 102.9(1).
Conclusion
Dichloro-triisopropylphenylphosphine 5:[33] Trip-P(Cl)Br was identified as
the main impurity beside small quantities of Trip-PBr2. The product slowly
crystallized at room temperature (1.45 g, 27%). Purer samples were obtained
by sublimation in vacuum (70 °C/10–3 mbar); but the mixed halogen com-
pounds were not completely removed. 1H NMR (C6D6, 300 K): δ (ppm) = 7.07
(d, 4JPH = 3.5 Hz, 2H, m-CH), 4.21 (d of sept, 3JHH = 6.8 Hz, 4JPH = 4.6 Hz, 2H,
We report on a new and facile synthetic method for the selective gen-
eration of various 3H-phosphaallenes in a multigram scale. It starts in
most cases with commercially available and easy to handle diethyl-
or diisobutylaluminium hydrides and diethynylphosphines, which are
accessible by standard methods. Hydroalumination of an ethynyl
group afforded compounds with a geminal arrangement of Al and P
atoms. The remaining alkynyl group is removed by elimination of di-
alkylaluminium alkynides. Chromatographic work-up destroys the
organoaluminium components and yields the phosphaallenes as vis-
cous liquids or colourless crystals. This method allows the generation
of aryl and so far unknown alkyl substituted phosphaallenes. Unstable
derivatives could be enriched and trapped by coordination to W(CO)5
or Pt(PR3)2 fragments. In the first case, the η1-coordination via a P-W
bond is observed, while with Pt the side-on coordination of the P=C
double bond gave three-membered PtPC heterocycles. Slow decom-
position of two transient 3H-phosphallenes yielded as previously un-
known secondary products diphosphines with P-P bonds and the P
atoms bound to an alkenyl or an alkynyl group. These compounds
may result from 1,3-H shift of the β-H atom of a phosphaallene to the
P atom and hydrophosphination of a P=C bond of a second molecule.
The facile access to these phosphaallenes allows their application in
various secondary reactions. They have functional groups with P=C
and C=C double bonds, the P atoms are nucleophilic and applicable
in coordination chemistry or oxidative addition, the central C atoms
bear a relatively high negative partial charge and may act as nucleo-
philes. The β-C-H bond possibly represents another reactive center.
Preliminary studies showed that thermal rearrangement with the per-
sistent Mes* derivatives yields unprecedented bicyclic P-H com-
pounds, which are applicable in hydrophosphination, while irradia-
tion afforded strained heterocyclic molecules. These 3H-phos-
phaallenes are fascinating starting materials with a promising reactiv-
ity, which is beyond the limited experience reported in the literature.
3
o-CHMe2), 2.64 (sept, JHH = 6.9 Hz, 1H, p-CHMe2), 1.23 (d, 3JHH = 6.8 Hz,
12H, o-CHMe2), 1.11 (d, 3JHH = 6.9 Hz, 6H, p-CHMe2); 31P{1H} NMR (C6D6,
300 K): δ (ppm) = 165.0.
Dichloro-supermesitylphosphine 6:[34] One impurity was identified as 1,3,5-
(Me3C)3C6H3]. The oil crystallized slowly at room temperature (10.1 g, 57%).
The product decomposed upon heating and could not be purified by sublima-
tion in vacuum. Recrystallization from small volumes of diethyl ether (-78 °C)
afforded 6 in a crystalline form and a higher purity. 1H NMR (C6D6, 300 K):
δ (ppm) = 7.48 (d, 4JPH = 2.8 Hz, 2H, m-CH), 1.60 (s, 18H, o-tBu), 1.18 (s, 9H,
p-tBu); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = 152.6.
Synthesis of the dialkynylphosphines 9 to 16; general procedure
The corresponding terminal ethyne (5 to 70 mmol) was dissolved in 20 to 80
mL of diethyl ether, cooled to 0 °C and treated with a solution of n-butyllith-
ium in n-hexane (1.6 M; equimolar quantity). The solution was warmed to
room temperature and stirred for 2 h. It was added to a cooled (0 °C) solution
of the corresponding dichlorphosphine (0.5 eq.) in 10 to 50 mL of diethyl ether.
The mixture was warmed to room temperature overnight. The solvent was re-
moved in vacuum and the residue treated with 30 to 100 mL of n-pentane.
Filtration, concentration of the filtrate and cooling to -30 °C (11: +3 °C) af-
forded colourless crystals of the diethynylphosphines. Slightly different pro-
cedures in the last step for 12 to 14 and 16.
Di(tert-butylethynyl)-triisopropylphenylphosphine 9: Yield: 51%; the
crystals contain often an impurity of triisopropylbenzene [1H:  = 6.98 (s, 3H,
aromatic ring); 2.81 (sept, 3H, CHMe2), 1.24 (d, 18H, Me); 13C:  = 149.1 (i-
C), 122.4 (o-C), 34.8 (CH), 24.4 (Me)]. Mp (argon, sealed capillary): 105 °C.
1H NMR (C6D6, 300 K): δ (ppm) = 7.16 (d, 4JPH = 3.0 Hz, 2H, m-H), 4.64 (d
of sept, 4JPH = 6.8 Hz, 3JHH = 6.8 Hz, 2H, o-CHMe2), 2.74 (sept, 3JHH = 6.9 Hz,
1H, p-CHMe2), 1.43 (d, 3JHH = 6.8 Hz, 12H, o-CHMe2), 1.17 (d, 3JHH = 6.9 Hz,
6H, p-CHMe2), 1.04 (s, 18H, CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm) =
155.2 (d, 2JPC = 17.0 Hz, o-C Trip), 151.7 (d, 4JPC = 1.4 Hz, p-C Trip), 127.7
(d, 1JPC = 2.5 Hz, i-C Trip), 122.6 (d, 3JPC = 5.7 Hz, m-C Trip), 115.4 (d, 2JPC
= 8.4 Hz, P-C≡C), 74.7 (P-C≡C), 34.8 (p-CHMe2), 32.6 (d, 3JPC = 20.2 Hz, o-
CHMe2), 30.6 (d, 4JPC = 1.4 Hz, CMe3), 28.8 (d, 3JPC = 1.1 Hz, CMe3), 25.1 (o-
CHMe2), 24.0 (p-CHMe2); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -87.6; IR
(paraffin, KBr plates): 휈̃ (cm–1) = 2193 w, 2154 w ν(C≡C); 1591 m, 1559 m
(aryl); 1458 vs, 1404 m, 1377 vs (paraffin); 1341 m, 1306 m, 1250 m δ(CH3);
1200 m, 1165 m, 1153 s, 1134 m, 1103 s, 1071 m, 1061 m, 1040 m, 974 w,
941 w, 880 w, 841 w, 816 w, 759 m ν(CC); 720 s (paraffin); 652 vw (aryl);
592 vw, 561 w, 529 w, 513 w, 482 w, 467 vw, 438 w, 419 w ν(PC), δ(CC);
Experimental Section
General methods:All manipulations were carried out under purified argon in
dried solvents (THF, diethyl ether and 1,4-dioxane with sodium/benzophe-
none; n-pentane, n-hexane and benzene with LiAlH4; dichloromethane and
6
This article is protected by copyright. All rights reserved.

10.1002/chem.201806334
Chemistry - A European Journal
MS (EI+, 25 eV, 323 K): m/z (%) = 396 (8) [M]+, 381 (100) [M – CH3]+;
microanalysis calc (%) for C27H41P (396.6): C: 81.8; H: 10.4; found: C: 81.6;
H: 10.4%.
= -71.8. IR (KBr pellet): 휈̃ (cm–1) = 3100 vw, 3030 vw, 2967 vs, 2930 vs, 2855
vs ν(CH); 2174 s, 2139 m ν(C≡C); 1593 m, 1533 w (aryl); 1472 s, 1447 s,
1408 w, 1393 s, 1360 s, 1312 vw, 1294 m, 1256 w δ(CH); 1234 s, 1211 m,
1194 w, 1179 w, 1123 w, 1078 m, 1024 vw, 968 vw, 941 vw, 922 w, 889 w,
876 m, 843 m, 785 m, 752 vw ν(CC); 671 m, 650 m, 596 w (aryl); 521 m, 507
m, 494 vw, 449 vw, 419 w ν(PC), δ(CC). MS (EI+, 20 eV, 363 K): m/z (%) =
490 (100) [M]+, 475 (24) [M – Me]+, 407 (34) [M – cHex]+; microanalysis calc
(%) for C34H51P (490.7): C: 83.2; H: 10.5; found: C: 83.1; H: 10.4.
Di(tert-butylethynyl)-supermesitylphosphine 10: Yield: 77%. Mp (argon,
1
4
sealed capillary): 112 °C. H NMR (C6D6, 300 K): δ (ppm) = 7.61 (d, JPH
=
2.8 Hz, 2H, m-H), 1.89 (s, 18H, o-CMe3), 1.25 (s, 9H, p-CMe3), 1.08 (s, 18H,
C≡C-CMe3); 13C NMR (C6D6, 300 K): δ (ppm) = 158.1 (d, 2JPC = 17.4 Hz, o-
C), 151.4 (d, 4JPC = 2.2 Hz, p-C), 127.8 (d, 1JPC = 33.7 Hz, i-C), 124.1 (d, 3JPC
=8.7 Hz, m-C), 116.9 (d, 2JPC = 11.6 Hz, C≡C-CMe3), 77.2 (d, 1JPC = 3.7 Hz,
Di(1-adamantylethynyl)-supermesitylphosphine 14: Similar to 12; color-
less crystals of 14 were obtained by cooling a saturated solution of the residue
in 1,2-difluorobenzene to 4 °C (68%). Mp (argon, sealed capillary): 222 °C.
1H NMR (C6D6, 300 K): δ (ppm) = 7.66 (d, 4JPH = 2.9 Hz, 2H, m-H), 1.95 (s,
18H, o-tBu), 1.85 (m, 12H, C2H2 Ad), 1.70 (d, 3JHH = 2.9 Hz, 6H, C3H Ad),
1.46 (m, 12H, C4H2), 1.28 (s, 9H,p-tBu); 13C{1H} NMR (C6D6, 300 K): δ
(ppm) = 158.1 (d, 2JPC = 17.4 Hz, o-C), 151.3 (d, 4JPC = 2.3 Hz, p-C), 128.1 (d,
1JPC = 25.6Hz, i-C), 124.2 (d, 3JPC = 8.7 Hz, m-C), 116.8 (d, 2JPC = 11.7 Hz, P-
C≡C), 77.6 (d, 1JCP = 3.2 Hz, P-C≡C), 42.4 (d, 4JPC = 2.1 Hz, C2 Ad), 40.4 (d,
3JPC = 4.7 Hz, o-CMe3), 36.5 (C4 Ada), 35.0 (p-CMe3), 34.8 (d, 4JPC = 8.0 Hz,
4
C≡C-CMe3), 40.3 (d, 3JPC = 4.7 Hz, o-CMe3), 35.0 (p-CMe3), 34.6 (d, JPC
=
8.0 Hz, o-CMe3), 31.3 (p-CMe3), 30.4 (d, 4JPC = 2.0 Hz, C≡C-CMe3), 29.0 (d,
3JPC = 1.5 Hz, C≡C-CMe3); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -72.3. IR
(paraffin, KBr plates): 휈̃ (cm–1) = 2199 w, 2149 m ν(C≡C); 1597 m, 1578 w,
1541 w, 1533 vw (aryl); 1462 vs, 1375 vs (paraffin); 1302 vw, 1252 s δ(CH3);
1202 w, 1179 w, 1157 w, 1123 w, 1078 w, 1028 w, 939 w, 920 w, 901 vw,
876 w, 847 vw, 773 m, 766 m, 754 w ν(CC); 721 m (paraffin); 657 w, 600 m
(aryl); 575 m, 554 m, 527 w, 488 w, 457 w, 436 w ν(PC), δ(CC); MS (EI+, 25
eV, 333 K): m/z (%) =438 (100) [M]+, 423 (27) [M – CH3]+, 381 (46) [M –
CMe3]+; microanalysis calc (%) for C30H47P (438.7): C: 82.1; H: 10.8; found
C: 82.6; H: 10.7.
3
m-CMe3), 31.4 (d, JPC = 1.7 Hz, C1 Ada), 31.3 (p-CMe3), 28.2 (C3 Ad);
31P{1H} NMR (C6D6, 300 K): δ (ppm) = -72.0; IR (KBr pellet): 휈̃ (cm-1) =
2963 vs, 2905 vs, 2849 vs ν(CH); 2162 m, 2135 w ν(C≡C); 1653 vw, 1595 m,
1560 w, 1531 w, 1477 m, 1450 s, 1408 vw, 1393 m, 1360 m, 1344 w, 1315 m
δ(CH); 1281 vw, 1238 w, 1211 w, 1180 w, 1153 m, 1123 w, 1098 w, 1026 vw,
974 vw, 928 w, 899 vw, 874 w, 810 vw, 779 m, 733 s ν(CC); 658 w, 650 m
(aryl); 594 w, 529 vw, 513 w, 500 w, 476 vw, 447 vw, 420 m ν(PC), δ(CC).
MS (EI+, 20 eV, 423 K): m/z (%) = 594 (100) [M]+, 579 (14) [M – Me]+, 537
Di(phenylethynyl)-supermesitylphosphine 11: Yield: 56%. Mp (argon,
1
4
sealed capillary): 135 °C. H NMR (C6D6, 300 K): δ (ppm) = 7.69 (d, JPH
=
3.1 Hz, 2H, m-H Mes*), 7.33 (m, 4H, o-H Ph), 6.88 (m overlap, 6H, m-H Ph
and p-H Ph), 1.95 (s, 18H, o-CMe3), 1.27 (s, 9H, s, p-CMe3); 13C{1H} NMR
(C6D6, 300 K): δ (ppm) = 158.7 (d, 2JPC = 17.6 Hz, o-C Mes*); 152.1 (d, 4JPC
= 2.4 Hz, p-C Mes*), 131.8 (d, 4JCP = 2.9 Hz, o-C Ph), 128.8 (p-C Ph), 128.5
t
(11) [M – Bu]+, 459 (90) [M – Ad]+; microanalysis calc (%) for C42H59P
1
3
(m-C Ph), 125.8 (d, JPC = 23.4 Hz i-C Mes*), 124.5 (d, JPC =9.1 Hz, m-C
(594.9): C: 84.8; H: 10.0; found: C: 84.9; H 10.0.
Mes*), 123.6 (d, 3JPC = 2.1 Hz, i-C Ph), 108.2 (d, 2JPC = 13.9 Hz, CC-Ph), 87.8
1
3
(d, JPC = 5.5 Hz, CC-Ph), 40.3 (d, JPC = 4.8 Hz, o-CMe3), 35.1 (p-CMe3),
34.5 (d, 4JCP = 7.6 Hz, o-CMe3), 31.2 (p-CMe3); 31P{1H} NMR (C6D6, 300 K):
δ (ppm) = -72.4. IR (KBr pellet): 휈̃ (cm–1) = 2961 s, 2909 m, 2866 m ν(CH);
2149 s ν(C≡C); 1969 vw, 1948 vw, 1896 vw, 1877 vw, 1800 vw, 1593 s, 1572
vw, 1533 w (aryl); 1485 s, 1441 w, 1408 w, 1393 w, 1362 s, 1279 vw δ(CH3);
1236 m, 1215 m, 1194 w, 1179 w, 1123 w, 1067 w, 1026 w, 943 vw, 912 w,
901 vw, 876 m, 845 s, 833 m, 754 vs ν(CC); 689 s, 669 vw, 652 m, 631 m
(aryl); 594 w, 536 m, 521 w, 496 vw, 469 w, 449 vw ν(PC), δ(CC); MS (EI+,
20 eV, 100 °C): m/z (%) = 478 (100) [M]+, 463 (22) [M – Me]+, 421 (18) [M
– tBu]+; microanalysis calc (%) for C34H39P (478.7): C: 85.3; H: 8.2; found: C:
85.2; H: 8.7.
Synthesis of bis(trimethylsilyl)methyl-di(tert-butylethynyl)phosphine 15:
1
Yield: 99%. Mp (argon, sealed capillary): 32 °C. H NMR (C6D6, 300 K): δ
(ppm) = 1.12 (s, 18H, tBu), 0.37 (d, 4JPH = 0.7 Hz, 18H, SiMe3), 0.23 (d, 2JPH
= 0.9 Hz, 2H, PCH); 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 115.0 (d, 2JPC
=
3.7 Hz, P-C≡C), 77.1 (d, 1JPC = 13.5 Hz, P-C≡C), 30.5 (CMe3), 28.7 (CMe3),
1
12.4 (d, JPC = 30.5 Hz, PCH), 2.0 (d, 3JPC = 5.6 Hz, SiMe3); 29Si{1H} NMR
(C6D6, 300 K): δ (ppm) = 3.0 (d, 2JPSi = 9.3 Hz, SiMe3). 31P{1H} NMR (C6D6,
300 K): δ (ppm) = -64.1. IR (paraffin, KBr plates): 휈̃ (cm-1) = 2187 vw, 2156
w ν(C≡C); 1456 s, 1377 m (paraffin); 1364 m, 1296 vw, 1251 s δ(CH3); 1202
w, 1088 m, 1065 m, 1047 m ν(CC); 1014 m δ(CHSi2); 997 w, 941 vw, 844 vs,
773 w ρ(CH3Si); 721 w (paraffin); 683 w ν(SiC); 569 w, 519 w, 461 w, 419 w
δ(CC), ν(PC). MS (EI+, 25 eV, 298 K): m/z (%) = 352 (69) [M]+, 337 (100)
[M – Me]+, 295 (32) [M – tBu]+; microanalysis calc (%) for C19H37PSi2 (352.6):
C: 64.7; H: 10.6; found: C: 64.2; H: 10.1.
Di(cyclohexenylethynyl)-supermesitylphosphine 12: In this case, the sol-
vent (n-pentane) was removed completely. Colorless crystals of 12 were ob-
tained by cooling a saturated solution in 1,2-difluorobenzene to 4 °C (65%).
Mp (argon, sealed capillary): 148 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.66
(d, 4JPH = 2.9 Hz, 2H, m-H Mes*), 6.06 (m, 2H, C=C cHex), 2.02 (m, 4H, m,
C6 cHex), 1.94 (s, 18H, o-CMe3), 1.72 (m overlap, 4H, C3 cHex), 1.27 (s over-
Synthesis of bis(trimethylsilyl)methyl-di(1-adamantylethynyl)phosphine
16: Similar to 12; the solvent was completely removed in vacuum. Colorless
crystals of 16 were obtained by cooling a saturated solution of the residue in
n-hexane to 4 °C (82%). Mp (argon, sealed capillary): 157 °C (dec). 1H NMR
(C6D6, 300 K): δ (ppm) = 1.90 (m, 12H, C2H2 Ad), 1.73 (d, 3JHH = 3.0 Hz, 6H,
C3H Ad), 1.47 (m, 12H, C4H2 Ad), 0.40 (s, 18H, SiMe3), 0.24 (s, 1H, PCH);
13C{1H} NMR (C6D6, 300 K): δ (ppm) = 114.8 (d, 2JPC = 3.4 Hz, P-C≡C), 77.5
(d, 1JPC = 13.3 Hz, P-C≡C), 42.6 (d, 4JPC = 1.4 Hz, C2 Ad), 36.5 (C4 Ad), 31.1
(d, 3JPC = 1.3 Hz, C1 Ad), 28.2 (C3 Ad), 12.5 (d, 1JPC = 30.3 Hz, PCH), 2.2 (d,
c
c
lap, 9H, p-CMe3), 1.27 (m overlap, 4H, C5 Hex), 1.21 (m, 4H, C4 Hex);
13C{1H} NMR (C6D6, 300 K): δ (ppm) = 158.3 (d, 2JPC = 17.4 Hz, o-C Mes*),
151.6 (d, 4JPC = 2.3 Hz, p-C Mes*), 136.2 (d, 4JPC = 3.8 Hz, C=C cHex), 127.2
1
3
(d, JPC = 24.4 Hz i-C Mes*), 124.2 (d, JPC = 8.9 Hz, m-C Mes*), 121.6 (d,
3JPC = 2.3 Hz, C=C Hex), 109.8 (d, JPC = 14.0 Hz, P-C≡C), 85.0 (d, JPC
=
c
2
1
3.5 Hz, P-C≡C), 40.3 (d, 3JPC = 4.7 Hz, o-CMe3), 35.0 (p-CMe3), 34.6 (d, 4JPC
= 7.9 Hz, o-CMe3), 31.3 (p-CMe3), 28.8 (d, 4JPC = 2.2 Hz, C6 cHex), 25.8 (C3
cHex), 22.4 (C5 cHex), 21.6 (C4 cHex); 31P{1H} NMR (C6D6, 300 K): δ (ppm)
= -72.3. IR (KBr pellet): 휈̃ (cm–1) = 3030 w, 2957 vs, 2934 vs, 2860 vs, 2830
s ν(CH); 2129 m ν(C≡C); 1759 vw, 1713 vw, 1624 w, 1593 s, 1547 w, 1533
m (aryl); 1476 s, 1433 m, 1393 s, 1360 s, 1300 vw, 1267 w, 1236 s δ(CH);
1211 m, 1171 s, 1123 m, 1076 vw, 1043 w, 1024 vw, 968 vw, 941 vw, 918 s,
899 vw, 866 m, 841 m, 799 m, 791 m, 754 vw ν(CC); 696 m, 683 w, 648 w,
596 m, 548 m ν(PC), δ(CC). MS (EI+, 20 eV, 393 K): m/z (%) = 486 (100)
3JPC = 5.5 Hz, SiMe3); 29Si{1H} NMR (C6D6, 300 K): δ (ppm) = 2.9 (d, 2JPSi
=
9.3 Hz, SiMe3). 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -64.1. IR (KBr pellet):
휈̃ (cm-1) = 2903 vs, 2851 vs ν(CH); 2164 m, 2133 vw ν(C≡C); 1450 m, 1396
vw, 1356 w, 1342 w, 1315 m, 1248 vs δ(CH); 1152 m, 1099 m ν(CC); 1022
m δ(CHSi2); 997 vw, 976 vw, 928 w, 845 vs, 795 m, 779 s, 729 m ρ(CH3Si);
683 m, 650 vw, 617 vw ν(SiC); 546 w, 527 vw, 519 vw, 471 vw, 444 vw, 417
w δ(CC), ν(PC). MS (EI+, 20 eV, 303 K): m/z (%) = 508 (100) [M]+, 493 (8)
[M – Me]+, 373 (52) [M – Ad]+; microanalysis calc (%) for C31H49PSi2 (508.9):
C: 73.2; H: 9.7; found: C: 72.9; H: 9.8.
t
[M]+, 471 (18) [M – Me]+, 429 (15) [M – Bu]+; microanalysis calc (%) for
C34H47P (486.7): C: 83.9; H: 9.7; found: C: 84.0; H: 9.6.
Synthesis of chloro-tert-butylethynyl-supermesitylphosphine 19: A cooled
(0 °C) solution of 3,3-dimethylbutyne (0.68 g, 8.29 mmol) in diethyl ether (30
mL) was treated with a solution of n-butyllithium in n-hexane (5.2 mL, 1.6 M,
8.32 mmol). The mixture was warmed to room temperature and stirred for 2
h. The resulting solution of the lithium alkynide was slowly added to a cooled
(-100 °C) solution of dichloro-supermesitylphosphine 6 (2.88 g, 8.30 mmol)
in 20 mL of diethyl ether. The suspension was slowly warmed to room tem-
perature, and all volatiles were removed in vacuum. The residue was treated
with n-pentane (30 mL). The resulting suspension was filtered, the filtrate con-
centrated and cooled -45 °C to obtain the alkynylphosphine as an amorphous
solid which had impurities of the corresponding dichlor- (6) and dial-
kynylphosphines (10) (about 10%). Careful sublimation of the solid material
(10-3 mbar, 90 °C) over a week yielded the colourless, analytically pure prod-
uct with minor impurities of 6 and 10 (2.08 g, 64%). Mp (argon, sealed capil-
lary): 84 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.58 (d, 4JPH = 2.8 Hz, 2H, m-
H), 1.79 (s, 18H, o-CMe3), 1.22 (s, 9H, p-CMe3), 1.04 (s, 9H, C≡C-CMe3);
Di(cyclohexylethynyl)-supermesitylphosphine 13: In the last step, the sol-
vent (n-pentane) was removed completely. Column chromatography (SiO2, n-
hexane/EtOAc 10/1 as eluent) and removal of the solvent from the eluate in
vacuum yielded 13 as colorless oil (78%). Colorless crystals of 13 were ob-
tained by cooling a saturated solution in dichloromethane to 4 °C. Mp (argon,
1
4
sealed capillary): 104 °C. H NMR (C6D6, 300 K): δ (ppm) = 7.60 (d, JPH
=
2.8 Hz, 2H, m-H), 2.30 (m, 2H, C1 cHex), 1.88 (s, 18H, o-tBu), 1.61 and 1.38
c
(each m, 4H, C2 cHex), 1.55 and 1.07 (each m, 4H,C3 Hex), 1.27 (s, 9H, p-
c
tBu), 1.27 and 1.11 (each m, 2H, C4 Hex); 13C{1H} NMR (C6D6, 300 K): δ
2
4
(ppm) = 158.1 (d, JPC = 17.4 Hz, o-C Mes*), 151.3 (d, JPC = 2.3 Hz, p-C
1
Mes*), 127.9 (d overlap, JPC = 26.0 Hz, i-C Mes*), 124.0 (d, 3JPC = 8.7 Hz,
m-C Mes*), 113.2 (d, 2JPC = 12.1 Hz, P-C≡C), 78.6 (d, 1JPC = 3.2 Hz, P-C≡C),
40.3 (d, 3JPC = 4.7 Hz, o-CMe3), 35.0 (p-CMe3), 34.7 (d, 4JPC = 8.1 Hz, o-CMe3),
4
c
3
32.3 (d, JPC = 2.4 Hz, C2 Hex), 31.4 (p-CMe3), 31.0 (d, JCP = 1.5 Hz, C1
cHex), 26.2 (C4 cHex), 25.0 (C3 cHex); 31P{1H} NMR (C6D6, 300 K): δ (ppm)
7
This article is protected by copyright. All rights reserved.

10.1002/chem.201806334
Chemistry - A European Journal
13C{1H} NMR (C6D6, 300 K): δ (ppm) = 159.1 (d, 2JPC = 21.5 Hz, o-C), 153.3
(d, 4JPC = 1.8 Hz, p-C), 132.6 (d, 1JPC = 66.9 Hz, i-C), 124.7 (d, 2JPC = 8.0 Hz,
P-C≡C), 124.3 (d, 3JPC = 8.0 Hz, m-C), 79.7 (d, 1JPC = 53.3 Hz, P-C≡C), 40.2
NMR (C6D6, 300 K): δ (ppm) = 6.46 (d, 3JPH = 37.5 Hz, 1H, C=C-H), 3.99 (br,
2H, o-CHMe2), 2.74 (overlap, 1H, p-CHMe2), 1.09 (s, 9H, C≡C-CMe3), 0.96
(s, 9H, C=C-CMe3), 0.40 and 0.42 (each s, 18H, SiMe3), 0.12 (s, 2H, CHSi2);
3
4
2
(d, JPC = 5.1 Hz, o-CMe3), 35.1 (p-CMe3), 34.7 (d, JPC = 9.2 Hz, o-CMe3),
13C{1H} NMR (C6D6, 300 K): δ (ppm) = 156.1 (d, JPC = 6.4 Hz, P-C=C),
4
3
2
31.1 (p-CMe3), 29.9 (d, JPC = 3.2 Hz, C≡C-CMe3), 29.2 (d, JPC = 3.1 Hz,
C≡C-CMe3); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = 45.5; IR (KBr plates,
paraffin): 휈̃ (cm-1) = 2195 w, 2143 m ν(C≡C); 1593 m, 1526 w (aryl); 1449 vs,
1410 w, 1375 vs (paraffin); 1304 w, 1283 w, 1252 m δ(CH); 1211 m, 1202 w,
1180 w, 1155 w, 1123 w, 1020 w, 941 w, 920 w, 901 w, 876 m, 770 s, 754 m
ν(CC); 721 s (paraffin); 650 w (aryl); 596 m, 561 w, 510 w, 469 w, 440 w
ν(PC), ν(PCl), (CC); MS (EI+, 20 eV, 298 K): m/z (%) = 392 (11) [M]+, 357
(100) [M – Cl]+ (plus the mass of 10); microanalysis calc (%) for C24H38PCl
(393.0): C: 73.3; H: 9.7; found: C: 73.4; H: 9.2.
151.9 (br, P-C=C), 115.4 (d, JPC = 8.7 Hz, P-C≡C), 81.7 (1JPC = 6.9 Hz, P-
C≡C), 37.9 (C=C-CMe3), 34.6 (p-CHMe2), 33.9 (d, 3JPC = 8.6 Hz, o-CHMe2),
30.8 (C≡C-CMe3), 30.1 (d, 4JPC = 3.5 Hz, C=C-CMe3), 28.8 (C≡C-CMe3), 8.6
(CSi2), 4.7 and 4.9 (SiMe3); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -55.2.
Treatment of the dialkynylphosphine 10 with H-Al[CH(SiMe3)2]2; synthe-
sis of the hydroalumination product: 10 (0.30 g, 0.68 mmol) was dissolved
in 10 mL of n-pentane and added to a cooled (0 °C) solution of H-
Al[CH(SiMe3)2]2 (0.24 g, 0.69 mmol) in 10 mL of n-pentane. The mixture was
warmed to room temperature and stirred for 30 min. Concentration and cool-
ing to -30 °C afforded colourless crystals of the hydroalumination product
similar to 2 (0.12 g, 23%). Decomposition was observed in solution and the
solid state and prevented elemental analysis and a complete spectroscopic
characterization. Important data: Mp (argon, sealed capillary): 123 °C (dec.).
1H NMR (C6D6, 300 K): δ (ppm) = 7.57 (d, 4JPH = 2.2 Hz, 2H, m-CH), 6.21 (d,
3JPH = 39.9 Hz, 1H, P-C=CH), 1.80 (s, 18H, o-CMe3), 1.31 (s, 9H, C≡C-
CMe3), 1.27 (s, 9H, p-CMe3), 0.69 (s, 9H, C=C-CMe3), 0.41 (s, 36H, SiMe3);
31P{1H} NMR (C6D6, 300 K): δ (ppm) = -43.4.
Synthesis of tert-butylethynyl-triisopropylphenylphosphine 21 via 18: H-
C≡C-CMe3 (0.052 g, 0.63 mmol), dissolved in 20 mL of diethyl ether, was
treated with a solution of n-BuLi in n-hexane (1.6 M, 0.40 mL, 0.64 mmol).
After 2 h at room temperature the mixture was added to a cooled (-100 °C)
solution of dichloro-triisopropylphenylphosphine 5 (0.19 g, 0.62 mmol) in 30
mL of diethyl ether. The mixture was warmed to room temperature and treated
with a solution of Li[HBEt3] (1 M in THF, 0.63 mmol, 0.63 mL). After 2 h,
all volatiles were removed in vacuum. Complete removal of BEt3 required
thorough evaporation of the residue at 10–3 mbar overnight. The residue was
treated with 20 mL of n-hexane. Filtration of the suspension and removal of
all volatiles in vaccum afforded the oily product 21, which contains several
impurities and could not be purified by crystallization. It was characterized by
31P NMR spectroscopy (δ = 42.6) and directly used for further reactions. Two
of the impurities were identified as dialkynylphosphine 9 and triisopropylben-
Synthesis of the supermesityl-3H-phosphaallenes 25[10] to 29; general pro-
cedure: The corresponding dialkynylphosphine (0.4 to 16 mmol) was dis-
solved in 10 to 50 mL of n-pentane or n-hexane, cooled to 0 °C and treated
with equimolar quantities of H-AlEt2 (slight excess of about 5%); H-AlEt2 can
be replaced H-AliBu2 without any problems. The solution was warmed to
room temperature, stirred for 12 h and treated with about 2 mL of water. Sep-
aration of the organic phase is helpful, but not necessary. Column chromatog-
raphy (SiO2, n-hexane as eluent) and removal of the solvent from the eluate in
vacuum overnight yielded the phosphaallene as a colourless oil or powder.
1
4
zene. H NMR (C6D6, 300 K): δ (ppm) = 7.12 (d, JPH = 2.0 Hz, 2H, m-H),
1
5.27 (d, JPH = 233.0 Hz, 1H, P-H), 4.07 (m, overlap, 2H, o-CHMe2), 2.73
3
3
(sept, JHH = 6.9 Hz, 1H, p-CHMe2), 1.35 (d, JHH = 6.7 Hz, 6H, o-CHMe2),
3
3
1.27 (d, JHH = 6.9 Hz, 6H, o-CHMe2), 1.168 and 1.170 (each 3 H, d, JHH
=
6.9 Hz, p-CHMe2), 1.07 (9 H, s, CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm)
2
1
= 154.0 (d, JPC = 13.2 Hz o-C), 150.9 (p-C), 125.3 (d, JPC = 9.6 Hz, i-C),
121.9 (d, 3JPC = 4.1 Hz, m-C), 113.1 (P-C≡C), 72.7 (d, 1JPC = 15.7 Hz, P-C≡C),
34.8 (p-CHMe2), 33.2 (o-CHMe2), 30.8 (CMe3), 28.8 (CMe3), 24.4 and 24.9
(o-CHMe2), 24.1 (p-CHMe2); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -124.1.
Supermesityl-3H-3-tert-butylphosphaallene 25: Colourless powder; yield:
75%; the solid material contains a minor impurity of supermesitylene. 1H
4
NMR (C6D6, 300 K): δ (ppm) = 7.54 (d, JPH = 1.6 Hz, 2H, m-CH), 5.70 (d,
3JPH = 27.7 Hz, 1H, P=C=CH), 1.74 (d, 5JPH = 0.7 Hz, 18H, o-CMe3), 1.25 (s,
9H, p-CMe3), 0.89 (s, 9H, C=C-CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm)
= 236.9 (d, 1JPC = 28.7 Hz, P=C=CH), 154.6 (d, 2JPC = 3.3 Hz, o-C), 149.8 (p-
Synthesis of tert-butylethynyl-supermesitylphosphine 22: This compound
has previously been obtained on another route.[11b] Chloro-tert-butylethynyl-
supermesitylphosphine 19 (2.14 g, 5.45 mmol) was dissolved in 30 mL of THF,
cooled to -30 °C and treated with Li[HBEt3] (1 M in THF, 5.66 mmol, 5.7 mL).
The mixture was slowly (1 h) warmed to room temperature and the solvent
removed in vacuum. The by-product BEt3 must be removed carefully. The
residue was treated with 20 mL of n-hexane. Filtration, concentration of the
filtrate and cooling to -45 °C afforded colourless blocks of 22 (1.57 g, 80%).
1H NMR (C6D6, 300 K): δ (ppm) = 7.60 (d, 3JPH = 2.5 Hz, 2H, m-H). 5.94 (d,
1JPH = 245.0 Hz, 1H, P-H), 1.75 (s, 18H, o-CMe3), 1.23 (s, 9H, p-CMe3), 1.02
(s, 9H, C≡C-CMe3); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -102.1.
1
2
C), 133.3 (d, JPC = 64.0 Hz, ipso-C), 123.2 (d, JPC = 12.2 Hz, P=C=CH),
122.2 (d, 3JPC = 1.2 Hz, m-C), 38.5 (o-CMe3), 35.0 (p-CMe3), 34.5 (d, 3JPC
=
10.3 Hz, C=C-CMe3), 33.9 (d, 4JPC = 7.5 Hz, o-CMe3), 31.4 (p-CMe3), 30.3 (d,
4JPC = 1.2 Hz, C=C-CMe3). 31P{1H} NMR (C6D6, 300 K): δ (ppm) = 74.4. IR
(paraffin, KBr plates): 휈̃ (cm–1) = 1761 w, 1726 m ν(P=C=C); 1591 s, 1543 m,
1526 m (aryl); 1454 vs, 1391 vs, 1377 vs (paraffin); 1360 vs, 1283 w, 1240 s
δ(CH3); 1213 s, 1179 s, 1128 s, 1026 m, 947 m, 924 m, 903 m, 876 m, 810 m,
754 m, 746 s ν(CC); 723 w (paraffin); 716 sh, 648 w (aryl); 594 w, 583 w, 536
m, 478 s ν(PC), δ(CC). Further characterization: see ref.[10]
.
3H-3-Phenyl-phosphaallene 26.[4,5,10,15] Colorless oil; yield: 86%. Crystals of
Synthesis of mesityl-3H-phosphaallene 23: Compound 23 was generated in
situ by hydroalumination of the dialkyne 8 with equimolar quantities of H-
Al[CH(SiMe3)2]2 in n-pentane at room temperature. After 8 h the phos-
phaallene has its maximum concentration (about 70%) as shown by NMR
spectroscopy. The mixtures was directly applied for secondary reactions, and
details are given together with procedures for the generation of the secondary
products. The characterization data have been published previously.[21]
1
26 were obtained by cooling a saturated solution in n-hexane to -45 °C. H
NMR (C6D6, 300 K): δ (ppm) = 7.55 (d, 4JPH = 1.6 Hz, 2H, m-H Mes*), 7.19
3
3
(d, JHH = 7.5 Hz, 2H, o-H Ph), 7.04 (pseudo-t, JHH = 7.5 Hz, 2H, m-H Ph),
3
3
6.95 (t, JHH = 7.5 Hz, 1H, p-H Ph), 6.59 (d, JHP = 26.9 Hz, 1H, P=C=CH),
1.72 (s, 18H, o-CMe3), 1.24 (s, 9H, p-CMe3); 31P{1H} NMR (C6D6, 300 K): δ
(ppm) = 75.5. MS (EI+, 20 eV, 343 K): m/z (%) = 378 (6) [M]+, 322 (100) [M
– butene]+, 321 (88) [M – tBu]+. This compound has been previously obtained
in low yields on other routes.[4,5,10,15]
Synthesis of triisopropylphenyl-3H-phosphaallene 24: Compound 24 was
obtained by hydroalumination of the corresponding dialkynylphosphine 9 with
equimolar quantities of H-Al[CH(SiMe3)2]2 in n-pentane at room temperature.
After about 6 h the phosphaallene is the main component (about 65%) of the
reaction mixture as determined by NMR spectroscopy. Hydroalumination
with the commercially available diisobutylaluminium hydride under the same
conditions gave identical results. The obtained mixtures were directly applied
for secondary reactions. Details are given together with the procedures for the
generation of the secondary products. The NMR spectra showed the reso-
nances of the intermediate hydroalumination product, the phosphaallene 24
and [(Me3Si)2HC]2Al-C≡C-CMe3.[24]. Data of the phosphaallene 24: 1H NMR
3H-3-Cyclohexenyl-phosphaallene 27. Colorless oil; yield: 0.78%. Crystals
of 27 were obtained by cooling a saturated solution in n-hexane to -70 °C. Mp
(argon, sealed capillary): 121 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.63 (d,
4JPH = 1.6 Hz, 2H, m-H), 6.46 (d, 3JHP = 27.3 Hz, 1H, P=C=CH), 5.42 (m, 1H,
C=C cHex), 2.17 and 1.91 (each m, 1H, C6 cHex), 1.82 (m, 2H, C3 cHex), 1.73
(s, 18H, o-CMe3), 1.36 (m, 2H, C5 cHex), 1.34 and 1.25 (each, m, 1H, C4 cHex,
1.27 (s, 9H, p-CMe3). 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 241.1 (d, 1JPC
= 25.5 Hz, P=C=CH). 154.6 (d, 2JPC = 3.3 Hz, o-C Mes*), 149.9 (p-C Mes*),
133.1 (d, 1JCP = 66.5 Hz, i-C Mes*), 128.8 (d, 3JPC = 10.1 Hz, C=C C1 cHex),
128.8 (d, 4JPC = 3.3 Hz, C=C C2 cHex), 122.3 (d, 3JPC = 1.2 Hz, m-C Mes*),
117.4 (d, 2JPC = 9.8 Hz, P=C=CH), 38.5 (d, 3JPC = 0.9 Hz, m-CMe3), 35.0 (p-
CMe3), 33.9 (d, 4JPC = 7.5 Hz, m-CMe3), 31.5 (p-CMe3), 27.4 (C6 cHex), 26.2
3
(C6D6, 300 K): δ (ppm) = 7.10 (s, 2H, m-CH), 5.81 (d, JPH = 25.7 Hz, 1H,
P=C=CH), 4.01 (sept, 3JHH = 6.8 Hz, 4JPH = 4.8 Hz, 2H, o-CHMe2), 2.74 (sept,
3JHH = 6.9 Hz, 1H, p-CHMe2), 1.33 (d, 3JHH = 6.8 Hz, 6H, o-CHMe2), 1.31 (d,
3JHH = 6.7 Hz, 6H, o-CHMe2), 1.18 (d, 3JHH = 6.9 Hz, 6H, p-CHMe2), 0.98 (s,
9H, CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 241.0 (P=C=CH), 151.8
(d, 2JPC = 7.2 Hz, o-C), 150.0 (p-C), 131.8 (ipso-C), 122.1 (d, 2JPC = 13.0 Hz,
c
c
(C3 Hex), 22.7 (C5 Hex), 22.3 (C4 cHex); 31P{1H} NMR (C6D6, 300 K): δ
(ppm) = 77.4. IR (KBr pellet): 휈̃ (cm–1) = 3098 vw, 2965 vs, 2918 vs, 2862 vs,
2826 s ν(CH); 1996 vw, 1923 vw, 1753 vw, 1734 vw, 1721 vw, 1701 vw, 1686
vw, 1653 vw, 1626 m, 1591 s, 1558 w, 1543 w, 1528 w, 1510 vw ν(C=C),
aryl; 1477 m, 1462 m, 1433 w, 1393 m, 1362 s, 1346 w, 1335 vw, 1283 vw,
1269 vw, 1240 s δ(CH); 1213 m, 1204 sh, 1186 w, 1130 m, 1074 vw, 1043 w,
1026 vw, 926 m, 905 w, 876 m, 862 m, 812 vw, 750 m ν(CC); 662 w, 650 w
(aryl); 594 w, 529 vw, 509 m, 469 m ν(PC), δ(CC). MS (EI+, 20 eV, 298 K):
3
P=C=CH), 121.8 (m-C), 34.7 (overlap, p-CHMe2), 33.8 (d, JPC = 2.1 Hz, o-
CHMe2), 33.0 (CMe3), 29.9 (d, 4JPC = 17.3 Hz, CMe3), 24.1 and 24.4 (overlap,
o-CHMe2), 24.0 (p-CHMe2); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = 56.0.
Data of the intermediate product obtained by hydroalumination of 9 with H-
Al[CH(SiMe3)2]2; overlap of resonances prevented a complete assignment: 1H
8
This article is protected by copyright. All rights reserved.

10.1002/chem.201806334
Chemistry - A European Journal
m/z (%) = 382 (9) [M]+, 367 (3) [M – Me]+, 325 (100) [M – tBu]+; microanal-
ysis calc (%) for C26H39P (382.6): C: 81.6; H: 10.3; found: C: 81.7; H: 10.2.
= 9.0 Hz, C1 Ad), 29.1 (C3 Ad), 18.9 (d, 1JPC = 64.1 Hz, PCH), 1.7 (d, 1JSiP
=
51.8 Hz, 3JPC = 4.0 Hz, SiMe3), 1.6 (d, 1JSiP = 52.0 Hz, 3JPC = 3.8 Hz, SiMe3);
29Si{1H} NMR (C6D6, 300 K): δ (ppm) = 2.4 (d, 2JSiP = 0.9 Hz, SiMe3), 1.5 (d,
2JSiP = 3.9 Hz, SiMe3); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = 73.1. MS (EI+,
20 eV, 308 K): m/z (%) = 350 (18) [M]+, 335 (17) [M – Me]+, 160 (100)
[C=CH-Ad]+. Characterization of di(tert-butyl)aluminium 1-adaman-
tylethynide: 1H NMR (C6D6, 300 K): δ (ppm) = 1.92 (m, 12H, C2H2 Ad), 1.64
(m, 6H, C3H Ad), 1.41 (s, 36 H, CMe3), 1.38 (m, 12H, C4H2 Ad); 13C{1H}
NMR (C6D6, 300 K): δ (ppm) = 151.2 (Al-C≡C), 79.6 (Al-C≡C), 42.3 (C2 Ad),
32.0 (overlap, C1 Ad and CMe3), 27.7 (C3 Ad), 25.9 (C4 Ad), 17.3 (br.,
CMe3); MS (EI+, 20 eV, 453 K): m/z (%) = 543 (10) [M – tBu]+, 243 (100)
[1/2M – tBu]+.
3H-3-Cyclohexyl-phosphaallene 28. Colorless oil; yield: 83%. Crystals of 28
were obtained by cooling a saturated solution in n-hexane to -45 °C. Mp (argon,
sealed capillary): 97 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.57 (d, 4JPH = 1.5
3
3
Hz, 2H, m-H), 5.57 (dd, JHP = 27.2 Hz, JHH = 7.6 Hz, 1H, P=C=CH), 2.07
(m, 1H, C1 cHex), 1.74 (s, 18H, o-CMe3), 1.68 and 1.01 (each m, 1H, C2 cHex),
1.54 and 1.06 (each m, 1H, C3 Hex), 1.42 and 0.99 (each m, 1H, C4 Hex),
1.42 and 0.84 (each m, 1H; C6 Hex), 1.41 and 1.00 (each m, 1H, C5 Hex),
1.26 (s, 9H, p-CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 238.4 (d, 1JPC
= 28.2 Hz, P=C=CH), 154.4 (d, 2JPC = 3.2 Hz, o-C), 149.8 (p-C), 133.3 (d, 1JPC
c
c
c
c
3
2
= 63.2 Hz i-C), 122.2 (d, JPC = 1.3 Hz, m-C), 116.9 (d, JPC = 12.5 Hz,
P=C=CH), 38.9 (d, 3JPC = 11.3 Hz, C1 cHex), 38.5 (o-CMe3), 35.0 (p-CMe3),
Synthesis of the supermesityl-3H-phosphaallene 25[10] by rearrangement:
tert-Butylethynyl-supermesitylphosphine 22 (0.07 g, 0.20 mmol) was dis-
solved in 20 mL of n-pentane and treated with DBU (3 mg, 3.0 µL, 0.02 mmol,
0.1 eq.) at room temperature. The rate of these reactions correlates to the con-
centration of DBU. The mixture was stirred for 2 h, the solvent removed in
vacuum and the residue dissolved in 2 mL of 1,2-difluorobenzene. Cooling of
the solution to -45 °C afforded a small quantity of colourless blocks of 25.
Separation of DBU by column chromatography over SiO2 with n-hexane as
the eluent and removal of the solvent from the eluate in vacuum afforded 25
as a colourless powder in high purity, but low yield.
4
c
4
33.7 (d, JPC = 7.5 Hz, m-CMe3), 33.4 (C2 Hex), 33.3 (d, JPC = 1.7 Hz, C6
cHex), 31.5 (p-CMe3), 26.1 (C4 cHex), 26.0 (C5 and C3 cHex); 31P{1H} NMR
(C6D6, 300 K): δ (ppm) = 66.6. IR (KBr pellet): 휈̃ (cm–1) = 3096 vw, 2967 vs,
2945 vs, 2932 vs, 2918 vs, 2849 vs ν(CH); 1938 vw, 1765 vw, 1732 w, 1630
vw, 1595 s, 1545 vw, 1531 w ν(C=C), aryl; 1477 s, 1462 s, 1445 vs, 1420 s,
1408 s, 1393 s, 1360 vs, 1281 vw, 1254 m δ(CH); 1238 s, 1213 s, 1200 m,
1180 m, 1126 m, 1084 vw, 1040 vw, 1026 vw, 966 w, 922 w, 903 w, 891 m,
876 s, 847 vw, 791 m, 754 w ν(CC); 650 w (aryl); 592 w, 561 w, 505 m, 484
w, 471 m, 430 vw ν(PC), δ(CC). MS (EI+, 20 eV, 323 K): m/z (%) = 384 (10)
[M]+, 369 (2) [M – Me]+, 328 (100) [M – butene]+; microanalysis calc (%) for
C26H41P (384.6): C: 81.2; H: 10.7; found: C: 81.0; H: 10.9.
W(CO)5 complex (32) of mesityl-3H-3-tert-butyl-phosphaallene: Di(tert-
butylethynyl)-mesitylphosphine 8 (0.45 g, 1.44 mmol) was dissolved in 15 mL
of n-hexane and treated at room temperature with H-Al[CH(SiMe3)2]2 (0.50 g,
1.45 mmol). The solution was stirred for 12 h and treated with a solution of
W(CO)5(THF) (in situ generated by irradiation of W(CO)6; 1.00 g, 2.84 mmol,
2.00 eq.) in 40 mL of THF. The mixture was stirred for 2 h, the volatiles were
removed in vacuo, and the residue was dissolved in a small quantity of n-hex-
ane. Column chromatography (SiO2, n-hexane as eluent) and removal of the
solvent from the eluate in vacuum yielded 32 as a yellow oil (0.38 g, 47%).
Yellow crystals of 32 were obtained by cooling a saturated solution in n-hex-
ane to -45 °C. Mp (argon, sealed capillary): 93 °C. 1H NMR (C6D6, 300 K): δ
3H-3-(1-Adamantyl)-phosphaallene 29. 1.2 Equivalents of the hydride were
applied in this case. Colorless oil, yield: 87%. A colorless amorphous powder
of 29 was obtained by cooling a saturated solution in benzene to 7 °C. 29 crys-
tallized with one molecule of benzene per formula unit. Mp (argon, sealed
capillary): 88 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.55 (s, 2H, m-H), 5.60
(d, 3JPH = 28.0 Hz, 1H, P=C=CH), 1.75 (s, 18H, o-CMe3), 1.78 (m, 3H, C3H
Ad), 1.51 (m overlap, 6H, C2H2 Ad), 1.49 (m overlap, 6H, C4H2 Ad), 1.25 (s,
9H, p-CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 237.7 (d, 1JPC = 28.6
Hz, P=C=CH), 154.6 (d, 2JPC = 3.2 Hz, o-C), 149.6 (p-C), 133.4 (d, 1JPC = 64.2
3
4
3
Hz, i-C), 123.2 (d, 2JPC = 12.3 Hz, P=C=CH), 122.2 (d, JPC = 1.2 Hz, m-C),
(ppm) = 6.59 (d, JPH = 3.0 Hz, 2H, m-H), 5.74 (1 H, d, JPH = 45.6 Hz,
P=C=CH), 2.55 (s, 6H, o-CH3), 1.95 (3 H, s, p-CH3), 0.91 (s, 9H, CMe3);
13C{1H} NMR (C6D6, 300 K): δ (ppm) = 236.1 (d, 1JPC = 88.8 Hz, P=C=CH),
42.9 (d, 4JPC = 1.1 Hz, C2 Ad), 38.6 (d, 3JPC = 0.8 Hz, m-CMe3), 36.9 (d, 3JPC
4
= 9.9 Hz, C1 Ad), 36.8 (C4 Ad), 35.0 (p-CMe3), 34.0 (d, JPC = 7.5 Hz,
2
1
2
m-CMe3), 31.4 (p-CMe3), 29.0 (C3 Ad); 31P{1H} NMR (C6D6, 300 K): δ (ppm)
= 73.7. IR (KBr pellet): 휈̃ (cm–1) = 2961 vs, 2914 vs, 2897 vs, 2847 vs ν(CH);
1591 m, 1557 w, 1531 w ν(C=C), aryl; 1477 m, 1450 s, 1406 w, 1393 m, 1360
s, 1344 vw, 1314 w, 1281 vw, 1238 m δ(CH); 1211 m, 1180 w, 1126 w, 1099
w, 1040 vw, 1024 vw, 984 w, 928 w, 901 w, 876 m, 822 w, 789 vw, 770 vw,
750 m, 714 vw ν(CC); 648 w, 621 m (aryl), 592 w, 501 m, 480 vw, 461 vw
ν(PC), δ(CC). MS (EI+, 20 eV, 323 K): m/z (%) = 436 (2) [M]+, 380 (100) [M
– butene]+; microanalysis calc (%) for C30H45P+ C6H6 (436.7 + 78.1): C: 84.0;
H: 10.0; found: C: 84.0; H: 10.4.
199.5 (d, JPC = 30.6 Hz, JWC = 152.0 Hz, CO ax), 195.6 (d, JPC = 9.7 Hz,
1JWC = 125.5 Hz, CO eq), 140.8 (d, JPC = 1.9 Hz, p-C), 139.8 (d, JPC = 7.1
Hz, o-C), 130.6 (d, 1JPC = 31.6 Hz, i-C), 129.4 (d, 3JPC = 7.5 Hz, m-C), 126.6
4
2
2
3
4
(d, JPC = 9.8 Hz, P=C=CH), 34.3 (d, JPC = 17.1 Hz, CMe3), 29.6 (d, JPC
=
1.3 Hz, CMe3), 22.8 (d, 3JPC = 8.2 Hz, o-CH3), 21.0 (d, 4JCP = 0.7 Hz, p-CH3);
31P{1H} NMR (C6D6, 300 K): δ (ppm) = 39.4 (1JPW = 262.4 Hz). IR (KBr pel-
let): 휈̃ (cm–1) = 2967 m, 2866 vw ν(CH); 2073 vs, 1973 vs, 1962 vs, 1940 vs,
1911 vs ν(CO); 1601 w, 1462 w, 1411 vw, 1377 vw, 1364 vw, 1294 vw, 1242
w δ(CH); 1177 vw, 1059 vw, 1030 vw, 1003 vw, 935 vw, 889 vw, 851 w, 816
w, 741 vw, 716 vw ν(CC); 625 m, 594 s, 571 s, 525 vw, 465 m, 438 m ν(PC),
δ(CC), ν(WC). MS (EI+, 20 eV, 333 K): m/z (%) = 556 (31) [M]+, 500 (30)
[M – 2CO]+, 472 (100) [M – 3CO]+; microanalysis calc (%) for C20H21O5PW
(556.2): C: 43.2; H: 3.8; found: C: 43.3; H: 3.7.
Bis(trimethylsilyl)methyl-3H-3-tert-butyl-phosphaallene 30: Bis(trime-
thylsilyl)methyl-di(tert-butylethynyl)phosphine 15 (0.21 g, 0.60 mmol) was
dissolved in 10 mL of n-hexane, cooled to 0 °C and treated with H-AlEt2
(0.052 g, 65 µL, 0.60 mmol). The solution was stirred for 5 d. Bis(trimethylsi-
lyl)methyl-3H-3-tert-butyl-phosphaallene 30 and the di(ethyl)aluminium tert-
butylethynide dimer were detected by NMR spectroscopy. 30 is stable towards
water, but decomposes on contact with air. Chromatographic work-up resulted
W(CO)5 complex (33) of triisopropylphenyl-3H-3-tert-butyl-phos-
phaallene: Di(tert-butylethynyl)-triisopropylphenylphosphine 9 (2.01 g, 5.07
mmol) in 70 mL of n-hexane was treated with H-AliBu2 (0.72 g, 0.91 mL, 5.07
mmol). The mixture was stirred for 6 h at room temperature to generate the
phosphaallene 24. W(CO)5THF (in situ generated by irradiation of W(CO)6:
1.96 g, 5.57 mmol, 1.1 eq.) in THF (150 mL) was added. Stirring was contin-
ued for 2 h. Column chromatography (n-hexane) afforded 33 as a yellowish
oil (0.90 g, 28%). Single crystals were obtained by recrystallization from n-
hexane at -45 °C. Elemental analysis gave the correct value for the hydrogen
content, while the carbon content was always found about 1.5% too low. Mp
(argon, sealed capillary): 157 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.05 (d,
4JPH = 3.5 Hz, 2H, m-H), 5.80 (d, 3JPH = 45.7 Hz, 1H, P=C=C-H), 3.97 (m, 2H,
1
3
in complete degradation. H NMR (C6D6, 300 K): δ (ppm) = 5.82 (d, JPH
=
23.6 Hz, 1H, P-C=CH), 1.01 (s, 9H, CMe3), 0.49 (dd, 2JPH = 4.4 Hz, 2JSiH = 4.5
Hz, 1H, PCH), 0.15 and 0.14 (each s, 9H, SiMe3); 13C{1H} NMR (C6D6, 300
K): δ (ppm) = 240.5 (d, 1JPC = 31.8 Hz, P=C=CH), 124.6 (d, 2JPC = 11.9 Hz,
P=C=CH), 33.4 (d, 3JPC = 9.1 Hz, CMe3), 29.9 (CMe3), 18.9 (d, 1JPC = 64.2 Hz,
PCH), 1.6 (d, JPC = 4.1 Hz, SiMe3), 1.4 (d, JPC = 3.9 Hz, SiMe3); 29Si{1H}
3
3
2
2
NMR (C6D6, 300 K): δ (ppm) = 2.3 (d, JPSi = 1.0 Hz, SiMe3), 1.5 (d, JPSi
=
3.9 Hz, SiMe3); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = 74.3.
Bis(trimethylsilyl)methyl-3H-3-(1-adamantyl)-phosphaallene 31: Bis(tri-
methylsilyl)methyl-di(1-adamantylethynyl)phosphine 16 (0.19 g, 0.37 mmol)
was dissolved in 5 mL of n-hexane, cooled to 0 °C and treated with H-AltBu2
(0.053 g, 0.37 mmol). The solution was stirred for 2 h. Bis(trimethylsilyl)me-
thyl-3H-3-(1-adamantyl)-phosphaallene 31 and the di(tert-butyl)aluminium 1-
adamantylethynide dimer were detected by NMR spectroscopy and mass spec-
trometry. The dimeric aluminium ethynide was isolated as a colorless amor-
phous powder by concentrating the reaction mixture. Colorless crystals were
obtained by cooling a saturated solution in dichloromethane to -30 °C. 31 is
stable towards water, but decomposes on contact with air. Chromatographic
work-up resulted in complete degradation. Characterization of 31: 1H NMR
(C6D6, 300 K): δ (ppm) = 5.76 (d, 3JPH = 24.3 Hz, 1H, P-C=CH), 1.90 (m, 3H,
C3H Ad), 1.68 (d, 3JHH = 2.8 Hz, 6H, C2H2 Ad), 1.60 (m, 6H, C4H2 Ad), 0.52
3
o-CHMe2), 2.66 (d, JHH = 6.9 Hz, 1H, p-CHMe2), 1.42 (overlap, 6H, o-
CHMe2), 1.31 and 1.27 (each overlap, 3H, o-CHMe2), 1.08 (d, 3JHH = 6.9 Hz,
6H, p-CHMe2), 0.94 (s, 9H, CMe3); 13C{1H} NMR (C6D6, 101 MHz, 300 K):
δ (ppm) = 235.1 (d, 1JPC = 90.4 Hz, P=C=C-H), 199.6 (d, 1JWC = 151.9 Hz, 2JPC
2
= 30.4 Hz, CO ax), 195.5 (d, 1JWC = 125.5 Hz, JPC = 9.6 Hz, CO eq), 152.2
(d, 4JPC = 2.5 Hz, p-C), 151.3 (o-C), 129.3 (d, 1JPC = 34.2 Hz, i-C), 126.4 (d,
2JPC = 9.6 Hz, P=C=C-H), 122.4 (br., m-C), 35.4 (br., o-CHMe2), 34.6 (p-
CHMe2), 34.2 (d, 3JPC = 17.1 Hz, CMe3), 29.5 (CMe3), 25.4, 25.1 and 24.3 (o-
CHMe2), 23.8 (p-CHMe2), 23.6 (o-CHMe2); 31P{1H} NMR (C6D6, 162 MHz,
300 K): δ (ppm) = 38.8 (1JWP = 265.1 Hz); IR (paraffin, KBr plates): 휈̃ (cm–1)
= 2073 m, 2000 w, 1981 s, 1950 s ν(CO); 1466 vs, 1379 vs (paraffin); 1348
m, 1341 w, 1308 w, 1242 w δ(CH); 935 w, 816 w ν(CC); 721 m (paraffin);
650 w (aryl); 592 m, 571 m, 534 m, 494 w, 467 w ν(PC), δ(CC), ν(WC); MS
(EI+, 25 eV, 313 K): m/z (%) = 640 (10) [M]+; 584 (100) [M – 2CO]+; 556
(51) [M – 3CO]+.
2
(d, JPH = 4.2 Hz, 1H, PCH), 0.22 (s overlap, 18H, SiMe3); 13C{1H} NMR
(C6D6, 300 K): δ (ppm) = 241.4 (d, 1JPC = 30.8 Hz, P=C=CH), 124.6 (d, 2JPC
=
12.0 Hz, P=C=CH), 42.7 (d, 4JPC = 1.0 Hz, C2 Ad), 37.0 (C4 Ad), 35.8 (d, 3JPC
9
This article is protected by copyright. All rights reserved.

10.1002/chem.201806334
Chemistry - A European Journal
W(CO)5 complex (34) of Mes*-3H-3-tert-butyl-phosphaallene: The phos-
phaallene 25 (0.44 g, 1.23 mmol) was dissolved in THF (20 mL) and treated
dropwise with a solution of W(CO)5(THF) (in situ generated by irradiation of
W(CO)6: 0.72 g, 2.05 mmol, 1.7 eq.) in THF (50 mL) at room temperature.
After 12 h the product was purified by column filtration (n-hexane) to yield
colorless crystals of 34 at -30 °C from a saturated n-hexane solution (0.61 g,
73%). Mp (argon, sealed capillary): 141 °C. 1H NMR (C6D6, 300 K): δ (ppm)
= 7.48 and 7.42 (each s, 1H, m-CH), 5.54 (d, 3JHP = 48.4 Hz, 1H, C=C-H), 1.72
and 1.67 (each s, 9H, o-CMe3), 1.19 (s, 9H, p-CMe3), 0.84 (s, 9H, C=C-CMe3);
13C{1H} NMR (C6D6, 101 MHz, 300 K): δ (ppm) = 238.3 (d, 1JPC = 85.8 Hz,
Treatment of phosphaallene 23 with (Ph3P)2Pt(C2H4); synthesis of 37:
Mes-P=C=C(H)-tBu 23 was generated in situ from the alkenyl-al-
kynylphosphine 2 (0.13 g, 0.20 mmol, 20 mL of n-hexane) as described above.
After 8 h at room temperature the solution was cooled to 0 °C and treated with
(Ph3P)2Pt(C2H4) (0.14 g, 0.19 mmol). The mixture was stirred at room temper-
ature for 1 h. All volatiles were removed in vacuo. The residue was dissolved
in a small volume of 1,2-difluorobenzene, and 37 was obtained as colourless
blocks upon cooling to -45 °C (0.058 g, 32%). Mp (argon, sealed capillary):
214 °C. 1H NMR (C6D6, 300 K): δ (ppm) = 7.57 (m, 6H, o-Ph2), 7.40 (m, 6H,
o-Ph1), 6.96 (m, 3H, p-Ph2), 6.95 (m, 6H, m-Ph2), 6.87 (m, 3H, p-Ph1), 6.81
(m, 6H, m-Ph1), 6.72 (s, 2H, m-Mes), 5.75 (dt, 3JPtH = 36.8 Hz, 3JPH = 16.0 Hz,
4JPH = 15.0 Hz, 1H, P-C=CH), 2.87 (s, 6H, o-Me), 2.15 (s, 3H, p-Me), 1.08 (s,
9H, CMe3); 13C{1H} NMR (C6D6, 101 MHz, 300 K): δ (ppm) = 143.5 (br., o-
Mes), 138.1 (br., P-C=C, HMBC), 137.8 (br., i-Mes), 137.0 (br., P-C=CH),
137.0 (dd, 1JPC = 41.0 Hz, 3JPC = 2.0 Hz, i-Ph1), 135.8 (dd, 1JPC = 41.0 Hz, 3JPC
P=C=C), 199.7 (d, 2JPC = 33.1 Hz, CO ax), 197.4 (dd, 1JWC = 127.4 Hz, 2JPC
=
2
2
8.2 Hz, CO eq), 155.7 (d, JPC = 1.6 Hz, o-C), 155.6 (d, JPC = 3.9 Hz, o-C),
152.2 (d, 4JPC = 2.5 Hz, p-C), 128.0 (i-C), 123.9 (d, 3JPC = 7.8 Hz m-C), 123.5
(d, 2JPC = 12.1 Hz, P=C=C), 122.3 (d, 3JPC = 8.0 Hz, m-C), 39.4 and 39.1 (o-
4
CMe3), 35.1 (C=C-CMe3), 35.0 (p-CMe3), 34.9 (d, JPC = 1.8 Hz, o-CMe3),
34.5 (d, JPC = 1.7 Hz, o-CMe3), 31.1 (p-CMe3), 30.0 (C=C-CMe3); 31P{1H}
= 2.0 Hz, i-Ph2), 135.5 (p-Mes), 134.8 (d, JPC = 13.4 Hz, JPtP = 18.4 Hz, o-
Ph2), 134.2 (d, 2JPC = 13.2 Hz, 3JPtC = 18.9 Hz, o-Ph1), 129.6 (d, 4JPC = 1.8 Hz,
p-Ph2), 129.4 (m-Mes), 129.3 (d, 4JPC = 1.8 Hz, p-Ph1), 128.1 (d, 3JPC = 9.8 Hz,
m-Ph2), 127.9 (d, 3JPC = 9.5 Hz, m-Ph1), 36.2 (d, 3JPC = 12.8 Hz, CMe3), 29.8
4
2
3
NMR (C6D6, 162 MHz, 300 K): δ (ppm) = 50.7 (1JWP = 276.2 Hz); IR (paraffin,
KBr plates): 휈̃ (cm–1) = 2073 w, 1948 m, 1910 w ν(CO); 1580 vs, 1558 vs
ν(C=C), aryl; 1450 vs, 1404 m, 1377 vs (paraffin); 1341 w, 1306 w δ(CH);
1113 m, br., 814 w ν(CC); 719 s (paraffin); 594 w, 561 w, 529 w, 513 w, 474
m, 447 m ν(PC), δ(CC), ν(WC); MS (EI+, 25 eV, 298 K): m/z (%) =682 (5)
[M]+, 625 (59) [M – 2CO – H]+, 569 (100) [M – 2CO – butene]+; microanalysis
calc (%) for C29H39O5PW (682.4): C: 51.0; H: 5.8; found: C: 51.3; H: 5.8.
(d, 4JPC = 4.6 Hz, CMe3), 26.6 (br., o-CH3), 21.1 (p-CH3); 31P{1H} NMR (C6D6,
2
300 K): δ (ppm) = 35.6 (dd, JPP = 55.1 and 23.8 Hz, JPPt = 3200 Hz, PPh1 -
3
trans), 28.7 (dd, JPP = 23.8 Hz and 12.3 Hz, JPtP = 3149 Hz, PPh2 -cis), –
2
1
3
2
1
128.7 (dd, JPP = 55.1 and 12.3 Hz, JPPt = 222.4 Hz, P=C=C); IR (paraffin,
KBr plates): 휈̃ (cm–1) = 1576 s, 1558 m ν(C=C), aryl; 1456 s 1400 w, 1377 s
(paraffin); 1341 w, 1306 w, 1246 w δ(CH3); 1155 w, 1113 w, 1094 w, 1047
w, 1028 w, 739 w ν(CC); 719 w (paraffin); 521 w, 498 w ν(PC), δ(CC). MS
(EI+, 20 eV, 453 K): m/z (%) = 951 (1) [M]+, 262 (100) [PPh3]+; microanalysis
calc (%) for C51H51P3Pt (952.0): C: 64.3; H: 5.4; found: C: 64.4; H: 5.7.
W(CO)5 complex (35) of bis(trimethylsilyl)methyl-3H-3-tert-butyl-phos-
phaallene: Bis(trimethylsilyl)methyl-di(tert-butylethynyl)phosphine 15 (0.58
g, 1.64 mmol) was dissolved in 20 mL of n-hexane, cooled to 0 °C and treated
with H-AlEt2 (0.15 g, 190 µL, 1.74 mmol). The solution was stirred for 5 d
and treated with a solution of W(CO)5(THF) (in situ generated by irradiation
of W(CO)6; 1.15 g, 3.27 mmol, 2 eq.) in 40 mL of THF. The mixture was
stirred for 2 h, the volatiles were removed in vacuo, and the residue was dis-
solved in a small quantity of n-hexane. Column chromatography (SiO2, n-hex-
ane as eluent) and removal of the solvent from the eluate in vacuum yielded
35 as a yellow oil (0.77 g, 79%). Yellow crystals of 35 were obtained by cool-
ing a solution in n-hexane to -45 °C. Mp (argon, sealed capillary): 108 °C. 1H
NMR (C6D6, 300 K): δ (ppm) = 5.77 (d, 3JPH = 43.1 Hz, 1H, P=C=CH), 0.97
Treatment of phosphaallene 25 with (Ph3P)2Pt(C2H4); synthesis of 38:
Phosphaallene 25 (0.20 g, 0.56 mmol) was dissolved in 20 mL of toluene,
cooled to 0°C and treated with (Ph3P)2Pt(C2H4) (0.38 g, 0.51 mmol, 0.9 eq.).
The mixture was stirred for 2 h at room temperature. All volatiles were re-
moved in vacuo, and the residue dissolved in CH2Cl2. Cooling of the solution
to -30 °C afforded the Pt complex 38 as a yellowish powder (0.38 g, 63%).
Single crystals were obtained from a benzene solution. Mp (argon, sealed ca-
pillary): 120 °C (dec.). 1H NMR (C6D6, 300 K): δ (ppm) = 7.61 (m, 6H, o-Ph2),
7.49 (m overlap, 7H, o-Ph1 and m-H Mes*), 7.47 (s, 1H, m-Mes*), 6.91 (m,
6H, p-Ph1 and p-Ph2), 6.89 (m, 12H, m-Ph1 and m-Ph2), 5.59 (dd, 3JPH = 16.0
Hz, 4JPH = 13.0 Hz, 3JPtH = 45.0 Hz, 1H, P-C=CH), 1.88 and 1.87 (each s, 9H,
2
(s, 9H, CMe3), 0.64 (d, JPH = 6.5 Hz, 1H, PCH), 0.18 and 0.15 (each s, 9H,
1
SiMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 233.4 (d, JPC = 88.2 Hz,
P=C=CH), 199.7 (d, 2JPC = 30.5 Hz, 1JWC = 151.0 Hz, CO ax), 196.3 (d, 2JPC
=
9.5 Hz, 1JWC = 125.7 Hz, CO eq), 129.1 (d, 2JPC = 8.0 Hz, P=C=CH), 34.5 (d,
3JPC = 16.4 Hz, CMe3), 29.3 (d, 4JPC = 1.5 Hz, CMe3), 26.2 (d, 1JPC = 14.4 Hz,
PCH), 4.4 and 2.4 (each d, 3JPC = 3.4 Hz, SiMe3); 29Si{1H} NMR (C6D6, 300
K): δ = 4.4 (d, 2JPSi = 14.1 Hz, SiMe3), 2.4 (d, 2JSiP = 14.7 Hz, SiMe3); 31P{1H}
NMR (C6D6, 300 K): δ (ppm) = 57.3 (1JWP = 259.9 Hz); IR (KBr pellet): 휈̃
(cm–1) = 2959 s, 2926 vs, 2855 s ν(CH); 2072 s, 1988 s, 1957 vs, 1923 vs
ν(CO); 1611 w, br. ν(C=C), aryl; 1462 m, 1408 w, 1364 w, 1304 vw, 1252 s
δ(CH); 1204 vw, 1180 w, 1096 m ν(CC); 1005 m δ(CHSi2); 937 w , 845 vs,
787 m, 772 w, 727 w ρ(CH3Si); 687 m ν(SiC); 594 m, 573 s, 556 w, 530 vw,
467 w, 437 w ν(PC), δ(CC), ν(WC); MS (EI+, 20 eV, 298 K): m/z (%) = 596
(31) [M]+, 540 (100) [M – 2CO]+; microanalysis calc (%) for C18H29O5PSi2W
(596.4): C: 36.3; H: 4.9; found: C: 35.9; H: 4.7.
o-CMe3), 1.38 (s, 9H, p-CMe3), 0.81 (s, 9H, CMe3); 13C{1H} NMR (C6D6, 101
2
MHz, 300 K): δ (ppm) = 160.6 (d, 2JPC = 33.4 Hz, o-Mes*), 155.1 (d, JCP
=
9.4 Hz, o-Mes*), 147.5 (p-Mes*), 141.3 (dd, 1JPC = 123.0 Hz, 3JPC = 5.0 Hz, i-
1
3
Mes*), 137.5 (m, br., P-C=CH), 137.5 (dd, JPC = 41.0 Hz, JPC = 2.0 Hz, i-
Ph1), 136.6 (dd, br., JPC = 7.0 Hz, JPC = 7.0 Hz, P-C=C), 135.2 (d overlap,
2
3
1JPC ca. 40 Hz, i-Ph2), 134.9 (d, JPC = 13.0 Hz, o-Ph2), 134.6 (d, JPC = 13.0
2
2
Hz, o-Ph1), 129.5 (br., p-Ph1), 129.4 (br., p-Ph2), 128.0 (d, 3JPC = 10.0 Hz, m-
Ph1), 127.9 (d, JPC = 9.0 Hz, m-Ph2), 122.9 (m-Mes*), 121.9 (d, JPC = 10.2
3
3
Hz, m-Mes*), 39.4 (d, 3JPC = 5.6 Hz, o-CMe3), 39.1 (o- CMe3), 36.6 (d, 3JPC
=
12.6 Hz, C=C-CMe3), 35.5 (o- CMe3), 34.8 (d, 4JPC = 19.0 Hz, o-CMe3), 34.7
(p-CMe3), 31.7 (p-CMe3), 29.8 (d, 4JPC = 4.4 Hz, C=C-CMe3); 31P{1H} NMR
(C6D6, 300 K): δ (ppm) = 30.9 (dd, 2JPP = 46.7 Hz, 2JPP = 28.9 Hz, 1JPtP = 3103
Hz, PPh1 -trans), 26.7 (dd, JPP = 28.9 Hz, JPP = 11.9 Hz, JPtP = 3237 Hz,
W(CO)5 complex (36) of bis(trimethylsilyl)methyl-3H-3-(1-adamantyl)-
phosphaallene: Bis(trimethylsilyl)methyl-di(1-adamantylethynyl)phosphine
16 (0.36 g, 0.71 mmol) was dissolved in 5 mL of n-hexane, cooled to 0 °C and
treated with H-AltBu2 (0.10 g, 0.70 mmol). The solution was stirred for 2 h
and treated with a solution of W(CO)5(THF) (in situ generated by irradiation
of W(CO)6; 0.49 g, 1.40 mmol, 2 eq.) in 20 mL of THF. The mixture was
stirred for 2 h, the volatiles were removed in vacuo, and the residue was dis-
solved in a small quantity of n-hexane. Column chromatography (SiO2, n-hex-
ane as eluent) and removal of the solvent from the eluate in vacuo yielded 36
as yellow oil (0.31 g, 66%). Yellow crystals of 36 were obtained by cooling a
saturated solution in n-hexane to -45 °C. Mp (argon, sealed capillary): 117 °C.
2
2
3
PPh2 -cis), –90.8 (dd, 2JPP = 46.7 Hz, 2JPP = 11.9 Hz, JPtP = 171 Hz, P=C=C);
3
IR (paraffin, KBr plates): 휈̃ (cm–1) = 1576 vs, 1558 s ν(C=C), aryl; 1462 vs,
1404 m, 1377 vs (paraffin); 1341 w, 1306 w δ(CH); 1113 m, br., 789 w ν(CC);
719 m (paraffin); 600 w, 559 w, 509 w, 467 m, 444 m ν(PC), δ(CC). MS (EI+,
20 eV, 403 K): m/z (%) = 1034 (1) [M – CO – Me]+, 262 (100) [PPh3]+; mi-
croanalysis calc (%) for C60H69P3Pt (1078.2): C: 66.8; H: 6.5; found: C: 66.1;
H: 6.5.
Decomposition of 23; formation of the diphosphine 39: Di(tert-butyl-
ethynyl)-mesitylphosphine 8 (1.00 g, 3.21 mmol) was dissolved in 20 mL of
n-hexane and treated at room temperature with a solution of H-
3
1H NMR (C6D6, 300 K): δ (ppm) = 5.73 (d, JPH = 43.5 Hz, 1H, P=C=CH),
1.87 (m, 3H, C3H), 1.63 (m overlap, 6H, C2H2), 1.57 (m, 6H, C4H2), 0.64 (d,
Al[CH(SiMe3)2]2 (1.11 g, 3.21 mmol) in 50 mL of n-hexane. The solution was
stirred for a week at room temperature. The diphosphine 39 (two diastere-
omers) and the corresponding alkynide dimer {Me3C-C≡C-
Al[CH(SiMe3)2]2}2 were detected by NMR spectroscopy and mass spectrom-
etry (39). Diastereomer A (2:3): 1H NMR (C6D6, 300 K): δ (ppm) = 6.82 (s,
2H, m-H Mes, C=C), 6.78 (s, 2H, m-H Mes, C≡C), 6.23 (ddd, 3JPH = 8.0 Hz,
2JPH = 4.0 Hz, 3JHH = 13.3 Hz, 1H, P-CH=CH), 5.91 (dd, 3JPH = 22.8 Hz, 3JHH
= 13.3 Hz, 1H, P-CH=CH), 2.96 (s, 6H, o-CH3, C≡C), 2.90 (s, 6H, o-CH3,
C=C), 2.10 (s, 3H, p-CH3, C≡C), 2.05 (s, 3H, p-CH3, C=C), 0.97 (s, 9H, C≡C-
CMe3), 0.94 (s, 9H, C=C-CMe3); 13C{1H} NMR (C6D6, 300 K): δ (ppm) =
2JPH = 6.6 Hz, 1H, PCH), 0.22 and 0.17 (each s, 9H, SiMe3); 13C{1H} NMR
(C6D6, 300 K): δ (ppm) = 234.7 (d, 1JPC = 87.9 Hz, P=C=CH), 199.8 (d, 2JPC
=
30.4 Hz, CO) ax), 196.4 (d, 2JPC = 9.5 Hz, 1JWC = 125.7 Hz, CO eq), 128.9 (d,
3
2JCP = 8.2 Hz, P=C=CH), 42.2 (d, 4JPC = 1.5 Hz, C2 Ad), 37.0 (d, JPC = 16.1
1
Hz, C1 Ad), 36.7 (C4 Ad), 28.8 (C3 Ad), 26.1 (d, JPC = 14.5 Hz, PCH), 1.4
and 1.3 (1JSiC = 52.7 Hz, SiMe3); 29Si{1H} NMR (C6D6, 300 K): δ = 4.4 (d,
2JPSi = 14.1 Hz, SiMe3), 2.2 (d, 2JPSi = 14.7 Hz, SiMe3); 31P{1H} NMR (C6D6,
300 K): δ (ppm) = 56.1 (1JWP = 260.7 Hz); IR (KBr pellet): 휈̃ (cm–1) = 2955 w,
2903 s, 2849 w ν(CH); 2072 s, 1987 s, 1933 vs, 1921 vs ν(CO); 1450 w, 1427
vw, 1344 vw, 1314 vw, 1250 m δ(CH); 1098 w ν(CC); 1005 w δ(CHSi2); 935
vw, 843 vs, 785 vw, 770 vw, 727 vw ρ(CH3Si); 687 w, 615 vw ν(SiC); 594 m,
571 m, 542 w, 474 vw, 440 vw ν(PC), δ(CC), ν(WC); MS (EI+, 20 eV, 323
K): m/z (%) = 674 (22) [M]+, 618 (100) [M - 2CO]+; microanalysis calc (%)
for C24H35O5PSi2W (674.5): C: 42.7; H: 5.2; found: C: 42.7; H: 5.2.
3
2
2
154.7 (dd, JPC = 17.3 Hz, JPC = 11.2 Hz, P-CH=CH), 145.5 (dd, JPC = 2.0
Hz, 3JPC = 18.0 Hz, o-C Mes, C≡C), 145.1 (dd, 2JPC =2.0 Hz, 3JPC = 16.0 Hz,
o-C Mes, C=C), 139.7 (p-C Mes, C=C), 139.0 (p-C Mes, C≡C), 131.9 (dd,
2
3
1JPC = 33.7 Hz, JPC = 7.8 Hz, i-C Mes, C=C), 130.2 (d, JPC = 4.7 Hz, m-C
3
1
Mes, C≡C), 130.1 (d, JPC = 3.7 Hz, m-C Mes, C=C), 127.2 (dd, JPC = 24.3
10
This article is protected by copyright. All rights reserved.

10.1002/chem.201806334
Chemistry - A European Journal
Hz, 2JPC = 10.8 Hz, i-C Mes, C≡C), 122.7 (dd, 1JPC = 31.0 Hz, 2JPC = 29.5 Hz,
ν(C≡C); 2068 s, 1983 m, 1944 vs, 1917 vs ν(CO); 1653 vw, 1601 w, 1558 vw
ν(C=C), aryl; 1472 w, 1458 w, 1443 w, 1408 vw, 1395 vw, 1362 vw, 1288 vw,
1252 vw δ(CH); 1215 vw, 1202 vw, 1030 vw, 943 vw, 897 vw, 851 vw, 775
vw, 735 vw ν(CC); 598 m, 575 m, 552 w, 428 w ν(PC), δ(CC). MS (EI+, 20
eV, 390 K): m/z (%) = 788 (4) [M]+, 555(100) [M – MesPCH=CH-tBu]+; mi-
croanalysis calc (%) for C35H42O5P2W (788.6): calc.: C 53.3; H 5.4; found: C
53.2; H 5.4.
P-CH=CH), 116.3 (d, 2JPC = 5.3 Hz, P-C≡C), 74.1 (dd, 1JPC = 17.9 Hz, 2JPC
=
14.1 Hz, P-C≡C), 35.1 (C=C-CMe3), 30.5 (C≡C-CMe3), 30.2 (d, 4JPC = 7.1 Hz,
C=C-CMe3),28.9 (C≡C-CMe3), 24.9 (dd, 3JPC = 16.0 Hz, 4JPC = 7.1 Hz, o-CH3,
C=C), 24.1 (dd, 3JPC = 18.0 Hz, 4JPC = 7.3 Hz, o-CH3, C≡C), 21.0 (p-CH3, C≡C
and C=C); 31P{1H} NMR (C6D6, 300 K): δ (ppm)= -47.2 (1JPP = 126.3 Hz, P-
1
CH=CH), -69.9 (1JPP = 126.3 Hz, P-C≡C); Diastereomer B (2:3): H NMR
(C6D6, 300 K): δ (ppm) = 6.65 (ddd, 3JPH = 7.0 Hz, 2JHP = 4.7 Hz, 3JHH = 13.5
Hz, 1H, P-CH=CH), 6.64 (s, 2H, m-H Mes, C=C), 6.61 (s, 2H, m-H Mes, C≡C),
6.22 (dd, 3JPH = 22.6 Hz, 3JHH = 13.5 Hz, 1H, P-CH=CH), 2.64 (s br., 6H, o-
CH3, C=C), 2.52 (s, 6H, o-CH3, C≡C), 1.99 (s, 3H, p-CH3, C≡C), 1.95 (s, 3H,
p-CH3, C=C), 1.19 (s, 9H, C≡C-CMe3), 1.06 (s, 9H, C=C-CMe3); 13C{1H}
Crystal structure determinations: Single crystals were obtained as noted
with the synthestic procedures. The crystallographic data was collected with
Bruker APEX II and Bruker D8 Venture diffractometers with multilayer optics
and Mo K radiation. The crystals were coated with a perfluorpolyether,
picked up with a glass fiber and immediately mounted in the cooled nitrogen
stream of the diffractometer. All non-hydrogen atoms were refined with ani-
sotropic displacement parameters; hydrogen atoms were calculated on ideal
positions and allowed to ride on the bonded atom with U = 1.2Ueq(C).[36]
CCDC–1883037 to -1883059 [compounds 9, 10, 12 to 16, 19, 22, 25 to 28, 32
to 38, 41, [tBu2Al-C≡C-Ad]2 and [(Me3Si)2HC]2Al[C=C(H)tBu]-
P(Mes*)(C≡C-tBu)] contain the supplementary crystallographic data for this
paper. These data are provided free of charge by the Cambridge Crystallo-
graphic Data Centre.
3
2
NMR (C6D6, 300 K): δ (ppm) = 153.6 (dd, JPC = 16.4 Hz, JCP = 8.1 Hz,
2
3
P-CH=CH), 145.7 (dd, JPC = 2.0 Hz, JPC = 17.0 Hz, o-C Mes, C=C), 145.2
(dd, JPC = 3.0 Hz, JPC = 15.0 Hz, o-C Mes, C≡C), 139.3 (p-C Mes,
2
3
1
2
C≡C),139.0 (p-C Mes, C=C), 131.0 (dd, JPC = 18.3 Hz, JCP = 13.2 Hz, i-C
Mes, C≡C), 129.9 (d, 3JPC = 3.9 Hz, m-C Mes, C≡C), 129.8 (d, 3JPC = 4.6 Hz,
1
2
m-C Mes, C=C), 126.5 (dd, JPC = 19.4 Hz, JPC = 11.4 Hz, i-C Mes, C=C),
123.7 (dd, 1JPC = 34.0 Hz, 2JPC = 19.4 Hz, P-CH=CH), 116.9 (d, 2JPC = 5.9 Hz,
P-C≡C), 75.7 (dd, 1JPC = 27.1 Hz, 2JPC = 13.2 Hz, P-C≡C), 35.2 (C=C-CMe3),
30.4 (C≡C-CMe3), 30.3 (d, 4JPC = 7.0 Hz, C=C-CMe3), 28.2 (C≡C-CMe3), 24.0
(o-CH3, C≡C), 23.6 (o-CH3, C=C), 20.98 (p-CH3, C≡C), 20.95 (p-CH3, C=C);
31P{1H} NMR (C6D6, 300 K): δ (ppm) = -52.5 (1JPP = 119.0 Hz, P-CH=CH), -
73.0 (1JPP = 119.0 Hz, P-C≡C); MS (EI+, 20 eV, 323 K): m/z (%) = 465 (18)
[M + H]+.
Acknowledgements
We gratefully acknowledge Chemtura (Germany) for the generous support
with HAlEt2 and HAliBu2.
Conflict of interest
W(CO)5 complex (41) of the diphosphine 39: A solution of the crude di-
phosphine 39 in n-hexane was obtained as described above. It was treated with
a solution of W(CO)5(THF) (in situ generated by irradiation of W(CO)6; 2.36
g, 6.71 mmol, 2 eq.) in 40 mL of THF. The mixture was stirred for 2 h. All
volatiles were removed in vacuo, and the residue was dissolved in a small
quantity of n-hexane. Column chromatography (SiO2, n-hexane/CH2Cl2 as el-
uent) and removal of the solvent from the eluate in vacuum yielded 41 as a
yellow oil, which contained some unknown impurities. Yellow crystals of 41
were obtained by cooling a saturated solution in n-hexane to -45 °C (1.47 g,
58%). Mp (argon, sealed capillary): 141 °C. Diastereomer A (5:1): 1H NMR
(C6D6, 300 K): δ (ppm) = 6.86 (ddd, 3JPH = 20.9 Hz, 2JPH = 3.2 Hz, 3JHH = 13.3
Hz, 1H, P-CH=CH), 6.69 (s, 1H, m-H Mes, C≡C), 6.62 (s br., 2H, m-H Mes,
C=C), 6.59 (s, 1H, m-H Mes, C≡C), 6.35 (dd, 3JPH = 28.7 Hz, 3JHH = 13.3 Hz,
1H, P-CH=CH), 2.80 (d, 4JPH = 2.5 Hz, 3H, o-CH3, C≡C), 2.69 (s, 3H, o-CH3,
C≡C), 2.32 (s br., 6H, o-CH3, C=C), 1.98 (s, 3H, p-CH3, C≡C), 1.97 (s, 3H, p-
CH3, C=C), 1.03 (s, 9H, C=C-CMe3), 0.96 (s, 9H, C≡C-CMe3); 13C{1H} NMR
(C6D6, 300 K): δ (ppm) = 200.3 (d, 2JPC = 23.9 Hz, COax), 198.4 (d, 2JPC = 6.0
The authors declare no conflict of interest.
Keywords: Phosphaallenes • hydroalumination • coordination compounds •
alkynylphosphines • frustrated Lewis pairs
[1]
Reviews: a) J. Escudie, H. Ranaivonjatovo, L. Rigon, Chem. Rev.
2000, 100, 3639–3696; b) J. Escudie, H. Ranaivonjatovo, Organome-
tallics 2007, 26, 1542–1559; c) M. Yoshifuji, Bull. Chem. Soc. Jpn.
1997, 70, 2881–2893.
[2]
a) M. Yoshifuji, K. Toyota, K. Shibayama, N. Inamoto, Tetrahedron
Lett. 1984, 25, 1809–1812; b) M. Yoshifuji, K. Toyota, K. Shibayama,
T. Hashida, N. Inamoto, Phosphorus Sulfur 1987, 30, 527–530.
[3]
[4]
[5]
G. Märkl, P. Kreitmeier, Angew. Chem. 1988, 100, 1411–1412; An-
gew. Chem. Int. Ed. Engl. 1988, 27, 1360–1361.
1
3
2
Hz, JWC = 127.4 Hz, COeq), 156.6 (dd, JPC = 22.9 Hz, JCP = 14.1 Hz,
M. Yoshifuji, S. Sasaki, N. Inamoto, Tetrahedron Lett. 1989, 30, 839–
842.
P-CH=CH), 145.0 (m, o-C Mes, C=C), 144.8 (d, 3JPC = 4.0 Hz, o-C Mes, C=C),
2
3
141.1 (dd, JPC = 2.0 Hz, JPC = 20.6 Hz, o-C Mes, C≡C), 139.7 (m overlap,
p-C Mes, C≡C and o-C Mes, C≡C), 139.3 (m, p-C Mes, C≡C), 131.6 (dd, 1JPC
= 30.1 Hz, 2JPC = 6.8 Hz, i-C Mes, C=C), 131.6 (d overlap, 3JPC = 9.2 Hz, m-C
Mes, C≡C), 131.6 (d overlap, 3JPC = 6.2 Hz, m-C Mes, C≡C), 130.2 (br., m-C
Mes, C=C), 129.4 (dd, 1JPC = 38.0 Hz, 2JPC = 19.4 Hz, i-C Mes, C≡C), 125.6
(d, 2JPC = 6.4 Hz, P-C≡C), 122.9 (dd, 1JPC = 27.6 Hz, 2JPC = 9.1 Hz, P-CH=CH),
a) R. Appel, V. Winkhaus, F. Knoch, Chem. Ber. 1986, 119, 2466–
2472; see also: b) A. I. Arkhypchuk, Y. V. Svyaschenko, A. Orthaber,
S. Ott, Angew. Chem. 2013, 125, 6612–6615; Angew. Chem. Int. Ed.
2013, 52, 6484–6487.
1
2
[6]
[7]
M. Hafner, T. Wegemann, M. Regitz, Synthesis 1993, 1247–1252.
75.1 (dd, JPC = 64.6 Hz, JPC = 2.9 Hz, P-C≡C), 35.4 (C=C-CMe3), 30.5 (d,
4JPC = 7.9 Hz, C=C-CMe3), 29.3 (d, 4JPC = 1.1 Hz, C≡C-CMe3), 29.1 (d, 3JPC
=
R. Appel, P. Fölling, B. Josten, M. Siray, V. Winkhaus, F. Knoch,
Angew. Chem. 1984, 96, 620–621; Angew. Chem. Int. Ed. Engl. 1984,
23, 619–620.
1.7 Hz, C≡C-CMe3), 25.9 (dd, 3JPC = 21.4 Hz, JPC = 12.2 Hz, o-CH3, C≡C),
25.6 (br., o-CH3, C=C), 25.0 (dd, 3JPC = 3.3 Hz, 4JPC = 0.6 Hz, o-CH3, C≡C),
20.8 (d, 5JPC = 0.7 Hz, p-CH3, C=C), 20.6 (p-CH3, C≡C); 31P{1H} NMR (C6D6,
300 K): δ (ppm) = -19.8 (1JPP = 272.1 Hz, P-CH=CH), -30.7 (1JPP = 272.1 Hz,
1JPW = 218.4 Hz, P-C≡C); Diasteroeomer B (5:1): 1H NMR (C6D6, 300 K): δ
(ppm) = 6.74 (s br., 2H, m-H Mes, C=C), 6.68 (s, 1H, m-H Mes, C≡C), 6.64
(s overlap, 1H, m-H Mes, C≡C), 6.15 (ddd, 3JPH = 17.3 Hz, 2JPH = 4.0 Hz, 3JHH
= 13.4 Hz, 1H, P-CH=CH), 5.85 (dd, 3JPH = 28.2 Hz, 3JHH = 13.4 Hz, 1H, P-
CH=CH), 2.92 (s, 3H, o-CH3, C≡C), 2.79 (s overlap, 3H, o-CH3, C≡C), 2.01
(s, 3H, p-CH3, C=C), 1.97 (s overlap, 3H, p-CH3, C≡C), 1.04 (s, 9H, C≡C-
CMe3), 0.92 (s, 9H, C=C-CMe3); ortho-Me groups of the second mesityl group
4
[8]
a) J.-C. Guillemin, T. Janati, J.-M. Denis, J. Chem. Soc., Chem. Com-
mun. 1992, 415–416; b) J.-C. Guillemin, T. Janati, J.-M. Denis, P.
Guernot, P. Savignac, Tetrahedron Lett. 1994, 35, 245–248.
[9]
Related method: S. Ito, S. Kimura, M. Yoshifuji, Org. Lett. 2003, 5,
1111–1114.
[10]
[11]
a) G. Märkl, S. Reitinger, Tetrahedron Lett. 1988, 29, 463–466; b) G.
Märkl, U. Herold, Tetrahedron Lett. 1988, 29, 2935–2938.
not detected; 13C{1H} NMR (C6D6, 300 K): δ (ppm) = 199.6 (d, JPC = 24.0
2
Hz, COax), 198.5 (d, 2JPC = 6.2 Hz, 3JPC = 0.9 Hz, COeq), 155.1 (dd, 3JPC = 21.0
Hz, 2JPC = 6.8 Hz, P-CH=CH), 145.9 (d, JPC = 5.8 Hz, o-C Mes, C=C), 145.7
(d, JPC = 5.5 Hz, o-C Mes, C=C), 140.8 (br., o-C Mes, C≡C), 140.4 (p-C Mes,
C=C), 139.7 (overlap, o-C Mes, C≡C), 131.4 (d, 3JPC = 9.6 Hz, m-C Mes, C≡C),
a) M. Yoshifuji, M. Shibata, K. Toyota, I. Miyahara, K. Hirotsu, Het-
eroatom Chem. 1994, 5, 195–200; b) G. Märkl, P. Kreitmeier, H. Nöth,
K. Polborn, Angew. Chem. 1990, 102, 958–960; Angew. Chem. Int.
Ed. Engl. 1990, 29, 927–929; c) R. Appel, J. Kochta, V. Winkhaus,
Chem. Ber. 1988, 121, 631–635.
3
132.2 (d, JPC = 5.4 Hz, m-C Mes, C≡C), 130.6 (br., m-C Mes, C=C), 130.0
(overlap, i-C Mes, C=C), 126.7 (m, i-C Mes, C≡C), 126.2 (dd, 2JPC = 1.6 Hz,
[12]
a) M. Yoshifuji, H. Yoshimura, K. Toyota, Chem. Lett. 1990, 827–
830; b) M. Yoshifuji, K. Toyota, H. Yoshimura, Phosphorus, Sulfur,
Silicon, Relat. Elem. 1993, 76, 67–70.
3JPC = 5.6 Hz, P-C≡C), 121.1 (dd, 1JPC = 35.4 Hz, 2JPC = 3.9 Hz, P-CH=CH),
1
2
76.7 (dd, JPC = 56.9 Hz, JPC = 4.5 Hz, P-C≡C), 35.1 (CMe3, C=C), 30.3 (d,
3JPC = 7.6 Hz, CMe3, C=C), 30.2 (m, CMe3, C≡C), 29.4 (d, 3JPC = 1.1 Hz, CMe3,
C≡C), 25.9 (br., o-CH3, C=C), 25.5 (dd, 3JPC = 16.6 Hz, 4JPC = 12.2 Hz, o-CH3,
C≡C), 25.5 (d, 3JPC = 2.5 Hz, o-CH3, C≡C), 21.0 (p-CH3, C=C), 20.6 (overlap,
p-CH3, C≡C); 31P{1H} NMR (C6D6, 300 K): δ (ppm) = -21.0 (1JPP = 316.6 Hz,
P-CH=CH), -46.8 (1JPP = 316.6 Hz, 1JWP = 227.4 Hz, P-C≡C); IR (KBr pellet):
휈̃ (cm–1) = 2965 m, 2930 w, 2901 vw, 2864 vw ν(CH); 2203 vw, 2159 w
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Chemistry - A European Journal
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Received: ((will be filled in by the editorial staff))
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Chemistry - A European Journal
Entry for the Table of Contents
Phosphaallenes
H. Klöcker, J. C. Tendyck. L. Ke-
weloh, A. Hepp, W. Uhl*
Page – Page
3H-Phosphaallenes form a fascinat-
the efficient generation of various
ing class of compounds with respect persistent and transient derivatives
to bonding and reactivity. Hydroalu- including alkyl compounds in a mul-
3H-Phosphaallenes Revisited:
Facile Synthesis via Hydroalumi-
nation of Alkynylphosphines and
β-Elimination, Stability and
Trapping of Transient Species by
Coordination to Transition Metal
Atoms
mination of dialkynylphosphines
and elimination of aluminium al-
kynides represent a new method for
tigram scale. Side-on coordination
of platinum atoms and a new decom-
position pathway are reported.
Keywords: Phosphaallenes / hydroalumination / coordination compounds / alkynylphosphines / frustrated Lewis
pairs
13
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