Synthesis and structure of the first η3-1,2-diphosphaallyl complexes

Article abstract of DOI:10.1002/ejic.200400995

Reaction of [(η⁵-C₅H₅)(CO) ₂M=P=C(SiMe₃)₂] [where M = Mo 1 (2), W (5)] with the phosphaalkene tBuP=C(NMe₂)₂ (1a) afforded the η³-1,2-diphosphaallyl complexes [(η⁵-C ₅H₅)-(CO)₂M{η³-tBuPPC(SiMe ₃)₂}], [where M = Mo (3a); M = W (6)]. Similarly, 2 and CyP=C(NMe₂)₂ (1b; where Cy = cyclohexyl) gave rise to the formation of [(η⁵-C₅H₅)(CO) ₂Mo-{CyPPC(SiMe₃)₂}] (3b) by a phosphinidene transfer process. Small amounts of [{η⁵-C₅H ₅)(CO)₂Mo}₂{η²: η²-Cy₃P₅}] (4) were formed as a minor product. However, treatment of 2 and 5 with HP=C(NMe₂)₂ (1c) yielded the complexes [{eta;⁵-C₅H₅)(CO) ₂M(η₂-(Me₃Si)₂CH-P=P-C(NMe ₂)₂}] [where M = Mo (9), W (10)]. The novel compounds 3a, 3b, 9 and 10 were characterized by means of spectroscopy (IR, ¹H, ¹³C{¹H}, ³¹P{¹H) NMR, MS). Moreover, the molecular structures of 3a, 3b, 4, 6 and 10 were determined by X-ray diffraction analysis. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).

Full text of DOI:10.1002/ejic.200400995

FULL PAPER
Synthesis and Structure of the First η3-1,2-Diphosphaallyl Complexes [(η5-
C5H5)(CO)2M{η3-RPPC(SiMe3)2}] (M = Mo, R = tBu, Cy; M = W, R =
tBu) from [(η5-C5H5)(CO)2M=P=C(SiMe3)2] (M = Mo, W) and Inversely
Polarized Phosphaalkenes RP=C(NMe2)2 (R = tBu, Cy)
Lothar Weber,*[a] Gabriel Noveski,[a] Ulrich Lassahn,[a] Hans-Georg Stammler,[a] and
Beate Neumann[a]
Keywords: Phosphavinylidene complexes / 1,2-Diphosphaallyl complexes / Phosphaalkenes / Molybdenum / Tungsten
Reaction of [(η5-C5H5)(CO)2M=P=C(SiMe3)2] [where M = Mo
(2), W (5)] with the phosphaalkene tBuP=C(NMe2)2 (1a) af-
forded the η3-1,2-diphosphaallyl complexes [(η5-C5H5)-
(CO)2M{η3-tBuPPC(SiMe3)2}], [where M = Mo (3a); M = W
(6)]. Similarly, 2 and CyP=C(NMe2)2 (1b; where Cy = cyclo-
hexyl) gave rise to the formation of [(η5-C5H5)(CO)2Mo-
{CyPPC(SiMe3)2}] (3b) by a phosphinidene transfer process.
Small amounts of [{η5-C5H5)(CO)2Mo}2{η2:η2-Cy3P5}] (4)
were formed as a minor product. However, treatment of 2
and 5 with HP=C(NMe2)2 (1c) yielded the complexes [(η5-
C5H5)(CO)2M{η2-(Me3Si)2CH–P=P–C(NMe2)2}] [where M =
Mo (9), W (10)]. The novel compounds 3a, 3b, 9 and 10 were
characterized by means of spectroscopy (IR, 1H, 13C{1H},
31P{1H} NMR, MS). Moreover, the molecular structures of 3a,
3b, 4, 6 and 10 were determined by X-ray diffraction analy-
sis.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
(alkoxy)carbene complexes of the Fischer type to form enol
ethers (see Scheme 2).[3]
Introduction
Inversely polarized phosphaalkenes R–P=C(NMe2)2 (I)
with an electron distribution Pδ–Cδ+ about the P=C double
bond may be described by two canonical formulae (I and
IЈ).[1] This situation may well be compared with the bonding
in phosphorus ylides II (see Scheme 1).[2]
Scheme 2.: Reaction of Fischer carbene complexes with Wittig rea-
gents.
Recently, we discovered that inversely polarized phos-
phaalkenes R–P=C(NMe2)2 [where R = tBu (1a), Me3Si
(1b)] react with aryl(alkoxy)carbene complexes affording
novel phosphaalkene complexes by a formal transfer of the
phosphinidene unit onto the carbene ligand (see
Scheme 3).[4]
Scheme 1. Mesomeric structures of inversely polarized phosphaalk-
enes (I) and phosphorus ylides (II).
The chemical behavior of both classes of compounds
(e.g. protonation, alkylation, complexation) can only be ra-
tionalized by using the zwitterionic structures IЈ and IIЈ.
Phosphorus ylides are prominent transfer reagents of al-
kylidene groups onto electrophilic functionalities (e.g. Wit-
tig reaction). Phosphorus ylides undergo reaction with aryl-
In contrast with this behavior, reaction of the carbene
complex III (where Aryl
= 2-MeOC6H4) with H–
P=C(NMe2)2 (1c) yielded the phosphaalkene complex IX as
a mixture of two isomers (see Scheme 4).[4]
In the present contribution we describe the smooth trans-
fer of phosphinidene units from phosphaalkenes 1 to the
electrophilic ligand in the phosphavinylidene complexes 2
and 5.
[a] Fakultät für Chemie der Universität Bielefeld
Universitätsstrasse 25, 33615 Bielefeld, Germany
Fax: +49-521-106-6146
E-mail: lothar.weber@uni-bielefeld.de
1940
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
DOI: 10.1002/ejic.200400995
Eur. J. Inorg. Chem. 2005, 1940–1946

Synthesis and Structure of the First η3-1,2-Diphosphaallyl Complexes
FULL PAPER
Purification of 3b was achieved by column chromatog-
raphy and crystallization of the crude yellow product from
n-pentane. A few crystals of the dinuclear complex 4 were
obtained from the concentrated mother liquors by cooling.
The 31P{1H} NMR spectra of 3a, 3b and 6 show doublets
at δ = 18.1, 2.4 and –10.7 ppm for the terminal phosphorus
atoms of the ligand whereas the central ones give rise to
doublets at δ = –6.8, –32.9 and –61,6 ppm. The coupling
1
constants JPP were determined as 407.0, 382.2 and
378.8 Hz, respectively. Only in the case of 3b, the 13C{1H}
NMR spectra displayed a doublet of doublets at δ = 43.8
2
(1JPC = 94.4; JPC = 6.9 Hz), which we assigned to the car-
bon atom of the diphosphaallyl ligand. Two discrete doub-
lets for the ortho- and meta-carbon atoms of the cyclohexyl
substituent agree with a centre of chirality at the central P
atom. The 13C NMR resonances of the carbonyl ligands
were observed as two singlets in 3a (δ = 234.3, 235.5 ppm),
as a doublet and a singlet at δ = 234.1 (2JPC = 47.1 Hz) and
δ = 235.6 ppm in 3b and as a singlet and a multiplet at δ =
224.4 and 227.7 ppm in 6. These resonances are shifted to
lower field than those for precursors 2 (δ = 230.4 ppm)[5b]
and 5 (δ = 218.9 ppm),[5b] indicating the improved donor
capacity of the diphosphaallyl ligands. This is also mirrored
by the carbonyl stretching frequencies in the IR spectra of
Scheme 3.: Reaction of Fischer carbene complexes with inversely
polarized phosphaalkenes.
Scheme 4.: Formation of IX.
3a, 3b and 6, which are observed as intense bands at ν =
˜
1943, 1877 (3a); 1930, 1859 (3b) and 1938, 1851 cm–1 (6).
The corresponding bands in the precursors 2 and 5 appear
Results and Discussion
at ν = 1944, 1882 cm–1 (KBr) and 1952, 1880 cm–1 (n-hex-
˜
Reaction of the phosphavinylidene complex [(η5-
C5H5)(CO)2Mo=P=C(SiMe3)2] (2)[5] with an equimolar
amount of phosphaalkene tBuP=C(NMe2)2 (1a)[4b] in tolu-
ene in the range of –30 °C to room temperature afforded
the yellow complex 3a, which was purified by column
chromatography on silica (31% yield). The air- and moist-
ure-sensitive compound is soluble in saturated hydro-
carbons, ethereal and aromatic solvents (see Scheme 5).
Similarly, compound 2 was converted into the orange pro-
duct 3b by treatment with CyP=C(NMe2)2 (1b) (49% yield).
Reaction of (η5-C5H5)(CO)2W=P=C(SiMe3)2 (5) with 1a
under comparable conditions led to the formation of com-
plex 6 (18%yield).
ane).[5b]
Single crystals of 3a suitable for an X-ray diffraction
study were grown from a diethyl ether/pentane mixture (1:9)
at –30 °C (see Figure 1). Compound 6 is isostructural to 3a,
and only the latter will be discussed in detail.[21]
Figure 1. Molecular structure of 3a in the crystal. Selected bond
lengths [Å] and angles [°]: Mo(1)–C(6) 1.9595(12), Mo(1)–C(7)
1.9686(11), Mo(1)–C(8) 2.4372(11), Mo(1)–P(1) 2.4960(3), Mo(1)–
P(2) 2.6756(3), P(1)–C(8) 1.7875(12), P(1)–P(2) 2.1234(4), P(2)–
C(15) 1.8977(12), C(8)–Si(1) 1.9032(12), C(8)–Si(2) 1.9013(12),
C(6)–Mo(1)–C(7) 80.84(5), C(6)–Mo(1)–C(8) 70.91(4), C(7)–
Mo(1)–P(2) 64.05(4), C(8)–P(1)–P(2) 97.68(4), P(1)–P(2)–C(15)
103.75(4), P(1)–C(8)–Si(1) 108.09, P(1)–C(8)–Si(2) 123.52(6).
Scheme 5.: Reaction of 2, 5 with RP=C(NMe2)2 (R = tBu, Cy).
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L. Weber, G. Noveski, U. Lassahn, H.-G. Stammler, B. Neumann
FULL PAPER
The analysis displays a molecule with a distorted piano-
stool geometry [P(2)–Mo(1)–C(7) 64.05(4)°, C(6)–Mo(1)–
C(7) 80.84(5)°, C(6)–Mo(1)–C(8) 70.91(4)°] and two nearly
linear carbonyl ligands [Mo(1)–C(6)–O(1) 173.84(10)°,
Mo(1)–C(7)–O(2) 173.09(11)°]. The most interesting part of
the molecule is the 1,2-diphosphaallyl ligand which is un-
symmetrically linked to the metal atom in an η3-fashion via
bonds Mo(1)–P(1) [2.4960(3) Å], Mo(1)–P(2) [2.6756(3) Å]
and Mo(1)–C(8) [2.4372(11) Å]. The latter bond length sig-
nificantly exceeds the Mo(1)–C distances displayed by the
[C5H5Mo] part of the molecule [2.3216(12)–2.3859(12) Å].
In the η3-1-phosphaallyl complex 7 the observed bond
lengths are Mo–C(1) 2.251(3) Å and Mo–C(2) 2.357(3) Å.[6]
In complex 7 the Mo–C contact to the central C atom of
the phosphaallyl ligand is markedly shorter than the corre-
sponding bond to the terminal C atom. Similarly, in com-
plex 3a the bond length between the metal and the terminal
phosphorus atom of the ligand Mo(1)–P(2) is strongly
lengthened [2.6756(3) Å] relative to the Mo(1)–P(1) bond
length [2.4960(3) Å]. In complex 7 a metal–phosphorus dis-
tance of 2.5343(8) Å was measured.[6] A comparable non-
symmetric ligation of the two phosphorus atoms is present
in the “butterfly complex” 8, featuring two short bonds
Mo(1,2)–P(1) [2.466, 2.470 Å] and two longer bonds
Mo(1,2)–P(2) [2.542, 2.546 Å].[7]
Figure 2. Molecular structure of 3b in the crystal. Selected bond
lengths [Å] and angles [°]: Mo(1)–C(6) 1.964(3), Mo(1)–C(7)
1.954(3), Mo(1)–C(14) 2.428(2), Mo(1)–P(1) 2.6538(6), Mo(1)–P(2)
2.4828(6), P(2)–C(14) 1.784(2), P(1)–C(8) 1.873(2), P(1)–P(2)
2.136(1), C(14)–Si(1) 1.907(2), C(14)–Si(2) 1.907(2); C(6)–Mo(1)–
C(7) 79.51(9), C(6)–Mo(1)–C(14) 70.05(8), C(7)–Mo(1)–P(1)
64.63(7), C(14)–P(2)–P(1) 97.95(8), P(2)–P(1)–C(8) 101.18(8), P(2)–
C(14)–Si(2) 110.28(12), P(2)–C(14)–Si(1) 120.21(12).
From the view-point of the rules according to Wade and
Mingos, 3a and 3b display four skeleton atoms with 14 skel-
eton electrons and thus have to be regarded as arachno clus-
ters.
A few crystals of compound 4 were collected from the
concentrated n-pentane mother liquor at +4 °C (see Fig-
ure 3). The complex contains a nearly planar central 2,4,5-
tri-cyclohexylcyclopentaphosphane-1,3-diyl ligand, which is
The distance P(1)–P(2) in 3a [2.1234(4) Å] is intermediate
between a double (ca. 2.00 Å)[8] and a single bond (ca.
2.22 Å).[9] In Cp2Mo(η2-P2H2)[10] and 8, the P–P bond
lengths amount to 2.146(3) Å and 2.136 Å, respectively. The
bond length P(1)–C(8) in 3a [1.7875(12) Å] exceeds that of
a localized and unsupported P–C double bond (1.65–
1.72 Å)[11] but is clearly shorter than a P–C single bond (av.
1.85 Å).[12] In 7 the corresponding bond length was deter-
mined as 1.755(3) Å. The η3-1,2-diphosphaallyl ligand in 3a
is oriented in a fashion in which the terminal atoms P(2)
and C(8) are directed towards the two carbonyl ligands.
Moreover, the tert-butyl substituent at P(2) is located in a
syn disposition with respect to P(1). The same is found for
the atom Si(1). Atoms C(15) and Si(1) are nearly coplanar
with the plane defined by the atoms P(2), P(1) and C(8)
[torsion angles C(8)–P(1)–P(2)–C(15) = 170.3°; P(2)–P(1)–
Figure 3. Molecular structure of 4 in the crystal. Selected bond
C(8)–Si(1) = –175.5°]. The substituent Si(2)Me3 at C(8) is lengths [Å] and angles [°]: Mo(1)–C(6) 1.958(3), Mo(1)–C(7)
1.959(3), Mo(1)–C(1–5) 2.295(2)–2.382(2), Mo(1)–P(1) 2.6204(6),
directed in an opposite way to the metal atom with a tor-
Mo(1)–P(2) 2.4272(6), Mo(2)–C(13) 1.961(3), Mo(2)–C(14)
sion angle P(2)–P(1)–C(8)–Si(2) = 47.1°.
1.958(2), Mo(2)–C(8–12) 2.344(2)–2.352(2), Mo(2)–P(3) 2.5964(6),
Mo(2)–P(4) 2.4480(6), P(1)–P(2) 2.1224(8), P(2)–P(3) 2.1948(8),
Single crystals of 3b were grown from pentane at +4 °C
(see Figure 2). The analysis shows a molecule, the core of
which is comparable to that of 3a with the cyclohexyl sub-
stituent and the group Si(2)Me3 directed towards the cen-
tral atom P(2) of the η3-diphosphaallyl ligand. All bond
parameters are similar to those in 3a and do not merit a
detailed discussion.
P(3)–P(4) 2.1281(8), P(4)–P(5) 2.2214(7), P(1)–P(5) 2.2320(8), P(2)–
C(27) 1.848(2), P(4)–C(15) 1.860(2), P(5)–C(21), 1.882(2), C(6)–
Mo(1)–C(7) 80.67(10), C(6)–Mo(1)–P(1) 77.03(7), C(7)–Mo(1)–
P(2) 83.80(7), C(13)–Mo(2)–C(14) 79.48(10), C(13)–Mo(2)–P(3)
71.83(1), C(14)–Mo(2)–P(4) 85.82(7), P(1)–P(2)–P(3) 118.98(3),
P(2)–P(3)–P(4) 97.47(3), P(3)–P(4)–P(5) 115.08(3), P(1)–P(5)–P(4)
104.00(3), P(2)–P(1)–P(5) 101.95(3).
1942
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Synthesis and Structure of the First η3-1,2-Diphosphaallyl Complexes
FULL PAPER
η2-coordinated to the Cp(CO)2Mo(1) unit via P(1) and P(2) complex 9 in 21% yield. The corresponding reaction of the
and to the Cp(CO)2Mo(2) group via atoms P(3) and P(4). tungsten analog [Cp(CO)2W=P=C(SiMe3)2] (5) with 1c was
Both metal complex fragments are located on opposite sides less straightforward and yielded only a few orange crystals
of the P5 ring. The bonds Mo(1)–P(1) [2.6204(6) Å] and of product 10 (see Scheme 7).
Mo(2)–P(3) [2.5964(6) Å] between the metal centers and the
tricoordinate P atoms are significantly longer than the
bonds between the metal centers and the four-coordinate
phosphorus atoms [Mo(1)–P(2) 2.4272(6) Å; Mo(2)–P(4)
2.4480(6) Å]. The longer Mo–P contacts may result from
repulsion between the lone pair of electrons at P(1) and P(3)
and the electron-rich metal atoms.
Interestingly, the η2-ligated P–P bonds P(1)–P(2)
[2.1224(8) Å] and P(3)–P(4) [2.1281(8) Å] are intermediate
between double [2.00 Å][8] and single bonds [2.22 Å],[9] thus
indicating some multiple bonding. In contrast to this, the
endocyclic bonds P(2)–P(3) [2.1948(8) Å], P(4)–P(5)
[2.2214(7) Å] and P(1)–P(5) [2.2320(8) Å] may be consid-
ered as single bonds. The cyclohexyl substituents at atoms
P(2) and P(5) are directed to the face opposite Mo(1) but
sterically approaching the Mo(2)(CO)2Cp moiety. To the
best of our knowledge, this mode of coordination of a P5
ring is without precedence.
Scheme 7. Formation of 9 and 10.
It is conceivable that the formation of complexes 3a, 3b
and 6 is initiated by a nucleophilic attack of the phosphaal-
The products are very soluble in ethereal and aromatic
kene by its P atom on the metal centre of precursors 2 or 5 solvents, whereas they appear to be nearly insoluble in satu-
to give adduct A. Ring closure and extrusion of C(NMe2)2 rated hydrocarbons. Compounds 9 and 10 are dicarbonyl-
would lead to metallodiphosphiranes B. A σ/π-type re- (cyclopentadienyl) complexes featuring the yet unknown di-
arrangement of B furnishes the final products 3a, 3b and 6 phosphaallyl anion [(Me3Si)2CH–P–P=C(NMe2)2]– as an
(see Scheme 6). Previously, Mathey et al. observed an equi- η2 ligand. The 31P{1H} NMR spectra of 9 and 10 displayed
librium between a vinylphosphenium tungsten complex and AB spin systems at δ = –70 and –75 ppm (1JAB = 421.9 Hz)
its η3-phosphaallyl isomer.[6b]
and δ = –105.8 (1JWP = 46.0 Hz) and –114.5 ppm (1JAB
=
1
400.0 Hz), respectively. In the H NMR spectrum of 9, the
singlets at δ = 0.29, 0.51, 2.49 and 5.06 ppm are attributed
to the CH and the Me3Si groups of the CH(SiMe3)2 substit-
uent, to the Me2N unit and the C5H5 ligand, respectively.
The 13C NMR resonance of the carbonyl ligands of 9 was
observed at δ = 203.7 ppm. In comparison with precursor
2 (δ = 230.4 ppm) this resonance is strongly shifted to high
field. It is also obvious from the ν(CO) stretching fre-
quencies in 9 (ν = 1889 s, 1803 cm–1) and 2 (KBr, ν = 1944
˜
˜
s, 1882 cm–1) that the novel ligand transfers more electron
density onto the [CpMo(CO)2] unit than the phosphavinyli-
dene ligand in 2. Orange crystals of 10 suitable for X-ray
diffraction analysis were grown from diethyl ether at 4 °C.
The results of this study are shown in Figure 4, while se-
lected bond lengths and bond angles are given in the cap-
tion. The compound consists of a central tungsten atom
linked to a cyclopentadienyl ring, two terminal carbonyl li-
gands, and the η2-(Me3Si)2CH–P–P=C(NMe2)2 diphos-
phaallylic ligand; the geometry around the tungsten atom
is that of a “four-legged piano-stool” type. The W–P bond
lengths [W(1)–P(1) 2.5352(7) Å, W(1)–P(2) 2.5695(7) Å] are
not equivalent.
Scheme 6. Proposed mechanism for the formation of 3a, 3b and 6.
Reaction of 2a and 5 with HP=C(NMe2)2 (1c)
The phosphavinylidene complex 2 was treated with an
The longer bond is similar to the corresponding dis-
equimolar amount of phosphaalkene HP=C(NMe2)2 tances found in [W(CO)5(μ,η2:η1:η1)-P2Cl2{W(CO)5}2],
(1c)[13] in diethyl ether in the range of –30 °C to room tem- that is, 2.573(4) and 2.582(4) Å.[14] According to structural
perature. Workup by chromatography on a column packed work by Huttner et al.[15] or Mathey et al.[16] on [W(CO)5-
with silica led to the isolation of the light yellow crystalline (μ,η2:η1:η1)-P2Ph2{W(CO)5}2] the W–P bonds of the W–
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1943

L. Weber, G. Noveski, U. Lassahn, H.-G. Stammler, B. Neumann
FULL PAPER
Conclusion
Inversely polarized phosphaalkenes RP=C(NMe2)2 serve
as convenient sources of the phosphinidene unit PR, which
can be transferred onto carbene ligands to afford η1-phos-
phaalkene complexes, as was shown previously. In this pa-
per, this synthetic principle is consistently extended to elec-
trophilic phosphavinylidene complexes, which are cleanly
converted into coordination compounds featuring the novel
η3-1,2-diphosphaallylic ligand. It is obvious that the per-
formed synthetic method may easily be generalized with
other electrophilic complexes containing vinylidene, phos-
phinidene, isocyanide and even carbonyl ligands. Moreover,
it is tempting to also test this kind of transfer reactions with
inversely polarized arsaalkenes.
Figure 4. Molecular structure of 10 in the crystal. Selected bond
lengths [Å] and angles [°]: W(1)–C(6) 1.946(3), W(1)–C(7) 1.957(3),
W(1)–C(1–5) 2.337(3)–2.398(3), W(1)–P(1) 2.5352(7), W(1)–P(2)
2.5695(7), P(1)–P(2) 2.1739(9), P(1)–C(8) 1.889(3), C(8)–Si(4)
1.906(3), C(8)–Si(5) 1.916(3), P(2)–C(15) 1.878(3), N(1)–C(15)
1.342(3), N(2)–C(15) 1.356(3), N(1)–C(16) 1.472(3), N(1)–C(17)
1.477(4), N(2)–C(18) 1.478(3), N(2)–C(19) 1.468(3); C(6)–W(1)–
C(7) 77.57(10), C(6)–W(1)–P(1) 84.84(7), C(7)–W(1)–P(2) 77.81(7),
C(8)–P(1)–P(2) 107.60(9), P(1)–P(2)–C(15) 102.64(8), P(2)–C(15)–
N(1) 123.15(19), P(2)–C(15)–N(2) 119.61(18), N(1)–C(15)–N(2)
117.1(2), C(8)–P(1)–P(2)–C(15) 150.4, P(2)–P(1)–C(8)–Si(4) –72.2,
P(2)–P(1)–C(8)–Si(5) 160.0.
Experimental Section
General: All manipulations were performed under dry, oxygen-free
nitrogen using standard Schlenk techniques. Solvents were vigor-
ously dried with an appropriate drying agent and freshly distilled
under N2 before use. The following compounds were prepared ac-
cording to literature procedures: [Cp(CO)2M=P=C(SiMe3)2] M =
Mo (2); M = W (5),[5] tBuP=C(NMe2)2 (1a),[4b] HP=C(NMe2)2
(1c);[13] CyPH(SiMe3),[17] [(Me2N)2CSMe]I.[18] IR spectra: Bruker
FT-IR VECTOR 22. 1H-, 13C- and 31P-NMR spectra: room temp.,
Bruker AM Avance DRX 500 (1H, 500.13 Hz; 13C, 125.75 MHz;
31P, 202.46 MHz). References: SiMe4 (1H, 13C), 85% H3PO4 (31P).
MS: Bruker Esquire Ion Trap mass spectrometer. Silica 60 (Merck)
was purchased commercially.
η2-P2Ph2 unit are significantly longer [2.604 Å (av)] than in
10. The elongation of the bond W(1)–P(2) with respect to
the bond W(1)–P(1) may be the result of steric repulsion
between the C5H5 ring and the bis(dimethylamino)carben-
ium unit. The P–P bond of 2.1739(9) Å is markedly longer
than the bonds in complexes [W(CO)5(μ,η2:η1:η1)-
P2Cl2{W(CO)5}2] [2.1460(6) Å] and [W(CO)5(μ,η2:η1:η1)-
P2Ph2{W(CO)5}2] [2.140(15) Å[15] and 2.163(3) Å[16]]. It is
possible to describe the bonding situation in 9 and 10 as
that of a diphosphametallacyclopropane with essentially
endocyclic single bonds, well aware of the fact that single
bonds in cyclopropane derivatives are usually shorter than
C–C bonds in unstrained C–C chains. The bond lengths
P(1)–C(8) [1.889(3) Å] and P(2)–C(15) [1.878(3) Å] are as
expected for single bonds. Carbon atom C(15) is trigonal
planar, the formal positive charge of this carbenium center
is stabilized by the planar atoms N(1) and N(2) by π conju-
gation, which becomes evident by the short C–N contacts
[N(1)–C(15) 1.342(3) Å and N(2)–C(15) 1.356(3) Å]. Such
CyP=C(NMe2)2 (1b): A solution of cyclohexyltrimethylsilylphos-
phane (18.8 g, 10.0 mmol) in 100 mL of THF was combined with
an equimolar amount of a 1.6 m solution of n-butyllithium in n-
hexane (6.25 mL, 10.0 mmol). The resulting slurry was added drop-
wise at 20 °C for 2 h to a slurry of N,N,NЈ,NЈ,S-pentamethylthiu-
ronium iodide (27.4 g, 10.0 mmol) in THF (20 mL). Stirring was
continued for 15 h. The solvent was removed in vacuo to afford an
orange, viscous residue. The latter was triturated with n-pentane
(150 mL) and filtered. The filter cake was washed with n-pentane
(2×20 mL) and subsequently with diethyl ether until the washings
became colorless. The orange-red filtrate was freed from solvents
in vacuo at 20 °C. The remaining oil was distilled to give 12.0 g
(56%) of 1b as a yellow oil (b.p. ca. 100 °C at 1.5×10–4 bar). H
NMR (C6D6): δ = 1.9 (m, 11 H, C6H11), 2.56 (s, 12 H, NMe2) ppm.
31P{1H} NMR (C6D6): δ = 57.5 (s) ppm. Because of the sensitivity
of the phosphaalkene no reliable elemental analyses were obtained.
1
[Cp(CO)2Mo{η3-tBuPPC(SiMe3)2}] (3a): A solution of 1a (0.24 g,
1.28 mmol) in toluene (10 mL) was added dropwise to a well-
stirred, chilled solution (–30 °C) of 2 (0.52, 1.29 mmol) in toluene
a situation is well known from η1 complexes of inversely (15 mL). It was slowly warmed to ambient temperature and stirring
polarized phophaalkenes.[1] The substituents at the P(2)
was continued for 72 h. The reaction mixture was freed from sol-
vent and volatile compounds. The black residue was transferred
onto a column (d = 1.5 cm, l = 6 cm) charged with silica. A yellow
phase was eluted with 40 mL of a diethyl ether/pentane mixture
(1:9). Removal of solvents in vacuo afforded 0.20 g (31%) of orange
unit are in an (E) disposition with the carbenium unit di-
rected towards the M(C5H5) fragment. The torsion angle
C(8)–P(1)–P(2)–C(15) amounts to 150.4°. For a rationaliza-
tion of the formation of 9 and 10 we postulate the formal
addition of the P–H bond of the phosphaalkene 1c to the
P=C double bond of 2 and 5 to yield the intermediate A.
Coordination of the second P atom to the metal atom with
its lone pair gives the observed metalladiphosphiranes (see
Scheme 7).
crystalline 3a. IR (KBr): ν = 1943 vs (CO), 1877 vs (CO), 1247 m
˜
[δ(SiMe3)], 847 m [(ρ(SiMe3)] cm–1. H NMR (C6D6): δ = 0.17 (d,
1
4JPH = 1.3 Hz, SiMe3), 0.47 (d, JPH = 1.3 Hz, SiMe3), 1.04 (dd,
4
4
3JPH = 10.8, JPH = 1.9 Hz, 9 H, tBu), 4.85 (s, 5 H, Cp) ppm.
13C{1H} NMR (C6D6): δ = 4.5 (d, JPH = 9.8 Hz, SiCH3), 8.8 (d,
3
3JCP = 11.3 Hz, SiCH3), 32.0 [dd, JPC = 14.4; 8.6 Hz, C(CH3)3],
1944
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Inorg. Chem. 2005, 1940–1946

Synthesis and Structure of the First η3-1,2-Diphosphaallyl Complexes
FULL PAPER
2
32.6 [d, JPC = 47.1 Hz, C(CH3)3], 90.7 (s, C5H5), 234.3 (s, CO),
1938 vs (CO), 1851 vs (CO), 1246 m [δ(SiMe3)], 847 m [ρ(SiMe3)]
235.2 (s, CO) ppm. 31P{1H} NMR (C6D6): δ = 18.1 (d, JPP
407 Hz, P-terminal), –6.8 (d, JPP = 407 Hz, P-central) ppm. 0.54 (s, 9 H, SiMe3), 1.04 (dd, JPH = 10.7, JPH = 1.3 Hz, 9 H,
=
cm–1. H NMR (C6D6): δ = 0.16 (d, JPH = 1.3 Hz, 9 H, SiMe3),
1
1
4
1
3
4
C18H32MoO2P2Si2 (494.50): calcd. C 43.72, H 6.52; found C 43.61,
H 6.52.
tBu), 4.89 (s, 5 H, C5H5) ppm. 13C{1H} NMR (C6D6): δ = 4.2 (d,
3JPC = 9.2 Hz, SiMe3), 9.0 (d, JPC = 11.5 Hz, SiMe3), 32.1 (dd,
3
JPC = 14.4, 8.6 Hz, C(CH3)3), 32.3 (dd, JPC = 49.6, 2.5 Hz, C-
(CH3)3), 89.1 (s, C5H5), 224.4 (s, CO), 222.7 (m, CO) ppm. 31P{1H}
NMR (C6D6): δ = –10.7 (d, 1JPP = 378.8 Hz, P-terminal), –61.6 (d,
1JPP = 378.8 Hz, P-central) ppm. MS (ESI): m/z = 583 [M + H+],
555 [M – CO + H+], 527 [M – 220 + H+]. C18H32O2P2Si2W
(582.41): calcd. C 37.12, H 5.54; found C 37.31, H 5.67.
[Cp(CO)2Mo{η3-CyPPC(SiMe3)2}] (3b) and [{Cp(CO)2Mo}2-η2,η2-
{P2(PCy)3}] (4):
A solution of CyP=C(NMe2)2 (1b) (0.27 g,
1.32 mmol) in toluene (15 mL) was added dropwise at room temp.
to a vigorously stirred solution of 2 (0.52 g, 1.32 mmol) in toluene
(15 mL). Stirring was continued for 72 h. Solvent and volatile com-
ponents were removed in vacuo to give a dark-brown solid residue.
The latter was chromatographed on a column (l = 6.5 cm, d =
20 cm) filled with silica. An orange-yellow zone was eluted with n-
pentane to afford 0.30 g (44%) of orange crystalline 3b after
recrystallization. A few orange crystals of compound 4 were iso-
[Cp(CO)2Mo{η2-(Me3Si)2CH–P=PC(NMe2)2}] (9): A solution of
1c (0.17 g, 1.31 mmol) in diethyl ether (10 mL) was added dropwise
with vigorous stirring to a chilled solution (–30 °C) of 2 (0.53 g,
1.31 mmol) in diethyl ether (15 mL). The brown reaction mixture
was warmed to ambient temp. and stirred for 24 h. Solvent and
volatile components were removed in vacuo. The black, oily residue
was transferred to a column (d = 1.5 cm, l = 6 cm) filled with silica.
A yellow phase, eluted with 40 mL of a diethyl ether/n-pentane
mixture (1:9) was discarded. Subsequently, a burgundy-red phase
was eluted with 40 mL of diethyl ether. Removal of solvent led to
lated from the mother liquor. IR (KBr): ν = 1930 vs (CO), 1859 vs
˜
(CO), 1246 m [δ(SiMe3)], 844 m [ρ(SiMe3)] cm–1. 1H NMR (C6D6):
δ = 0.18 (s, 9 H, SiMe3), 0.45 (s, 9 H, SiMe3), 0.88–1.90 (m, 11 H,
C6H11), 4.79 (s, 5 H, C5H5) ppm. 13C{1H} NMR (C6D6): δ = 3.90
3
3
(d, JPC = 9.2 Hz, SiMe3), 8.1 (d, JPC = 10.3 Hz, SiCH3), 26.0 (s,
1
C–Cy), 27.1(d, JPC = 8.1 Hz, PCH), 32.9 (dd, JPC = 14.4, 5.2 Hz,
C–Cy), 37.3 (dd, JPC = 15.5, 2.9 Hz, C–Cy), 42.7 (d, JPC = 13.8 Hz,
the isolation of the orange solid 9. IR (KBr): ν = 1889 (s, CO),
˜
1
2
1
C–Cy), 43.0 (d, JPC = 13.8 Hz, C–Cy), 43.8 (dd, JPC = 95.4, JPC
1803 s (CO), 1260 m [δ(SiMe3)], 840 s [ρ(SiMe3)] cm–1. H NMR
2
1
= 6.9 Hz, PPC), 91.4 (s, C5H5), 234.1 (d, JPC = 47.1 Hz, CO), (C6D6): δ = 0.29 (s, H, CHSi2), 0.51 (s, 18 H, SiMe3), 2.49 (s, 12
1
235.6 (s, CO) ppm. 31P{1H}NMR (C6D6): δ = –32.9 (d, JPP
=
H, NMe2), 5.06 (s, 5 H, C5H5) ppm. 13C{1H} NMR (C6D6): δ =
1
2
2
382.2 Hz, P-central), 2.4 (d, JPP
=
383.2 Hz, P-terminal).
2.3 (d, JCP = 7 Hz, SiCH3), 3.7 (d, JCP = 7 Hz, SiCH3), 16.9 (d,
1JCP = 79.3 Hz, CHSi2), 42.5 (br. s, NCH3), 44.2 (br. s, NCH3),
91.3 (s, C5H5), 203.7 (s, CO) ppm. 31P{1H} NMR (C6D6): δ =
C20H34MoO2P2Si2 (520.54): calcd. C 46.15, H 6.58; found C 46.13,
H 6.53.
1
–70.0, –75.0 [AB-spin system, JPP = 421 Hz, (Me2N)CP and
[Cp(CO)2W{η3-tBuPPC(SiMe3)2}] (6): A solution of 1a (0.224 g,
1.3 mmol) in toluene (25 mL) was added dropwise at room temp.
to a well-stirred solution of 5 (0.65 g, 1.3 mmol) in toluene (25 mL).
After stirring for 48 h, solvent and volatile compounds were re-
moved in vacuo. The dark-brown solid residue was chromato-
graphed on silica with pentane, as described before. A yellow zone
was eluted with pentane (230 mL). From this elute, compound 6
PCH(SiMe3)2] ppm. MS (ESI): m/z = 541 [M + H+]. C19H36MoN2-
O2P2Si2 (538.56): calcd. C 42.37 H 6.74 N 5.06, found C 41.88 H
6.64 N 5.20).
[Cp(CO)2W{η2-(Me3Si)2CH–P=P–C(NMe2)2}] (10): Analogously,
equimolar amounts of 1c (0.17 g, 1.30 mmol) and 5 (0.64 g,
1.30 mmol) were allowed to react in diethyl ether (10 mL). Analo-
gous workup by chromatography and recrystallization from diethyl
was isolated as a yellow solid (0.14 g, 18% yield). IR (KBr): ν =
˜
Table 1. Crystal data and data-collection parameters.
3a
3b
4
10
Empirical formula
Mr [gmol–1]
Crystal dimensions [mm]
Crystal system
Space group
a [Å]
C18H32MoO2P2Si2
494.50
0.30×0.25×0.10
monoclinic
P21/c
13.7330(1)
11.5360(1)
14.7690(1)
102.1270(7)
2287.55(3)
4
C20H34MoO2P2Si2
520.53
0.16×0.09×0.04
monoclinic
P21/n
7.8680(2)
34.6270(5)
9.0300(2)
98.5600(7)
2432.77(9)
4
C32H43Mo2O4P5
838.39
0.15×0.13×0.04
monoclinic
P21/n
11.6440(2)
10.8760(2)
27.8690(4)
98.9550(8)
3486.31(10)
4
C19H36N2O2P2Si2W
626.47
0.24×0.07×0.03
monoclinic
P21/c
21.437(2)
9.7132(8)
12.8112(17)
101.664(10)
2612.5(5)
4
b [Å]
c [Å]
β [°]
V [Å3]
Z
ρcalcd. [gcm–3]
1.436
0.827
1.421
0.782
1.597
0.984
1.593
4.652
μ [mm–1]
F(000)
θ [°]
No. refl. collected
No. refl. unique
R (int)
1024
3.33–30.00
64677
6649
0.031
1080
3.16–25.00
28194
4281
0.050
1704
2.96–27.50
62827
7959
0.053
1248
3.09–30.00
58131
7603
0.0563
No. refl. [I Ͼ 2σ (I)]
Refined parameters
GOF
RF [(I Ͼ 2σ (I)]
wRF2 [I Ͼ 2σ (I)]
Δρmax./min. [eÅ–3]
6054
235
1.062
0.0206
0.0520
0.482/–0.462
3656
250
1.040
0.0248
0.0559
0.365/–0.363
6421
388
1.032
0.0280
0.0637
0.479/–0.384
6213
263
1.040
0.0238
0.0501
0.932/–0.715
Eur. J. Inorg. Chem. 2005, 1940–1946
www.eurjic.org
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
1945

L. Weber, G. Noveski, U. Lassahn, H.-G. Stammler, B. Neumann
FULL PAPER
1
[7] D. Fenske, K. Merzweiler, Angew. Chem. 1986, 98, 357–368;
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[9] K. F. Tebbe, Z. Anorg. Allg. Chem. 1980, 468, 202–212.
[10] E. Camillo, A. Coda, K. Prout, J.-C. Daran, Acta Crystallogr.
Sect. B 1977, 33, 2608–2611.
ether led to a few burgundy-red crystals of 10. H NMR (C6D6): δ
= 0.28 (s, 1 H, CHSi2), 0.51 (s, 18 H, SiMe3), 2.45 (s, 12 H, NMe2),
5.05 (s, 5 H, Cp) ppm. 31P{1H} NMR (C6D6): δ = –105.8 [AB spin
1
1
system, JPP = 400, JWP = 46 Hz, PCH(SiMe3)2], –114.5 [AB spin
1
system, JPP = 400 Hz, (MeN)2CP] ppm.
[11] Review: L. Weber, Angew. Chem. 1996, 108, 292–310; Angew.
Chem. Int. Ed. Engl. 1996, 35, 271–288.
[12] D. D. C. Corbridge, The Structural Chemistry of Phosphorus,
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[13] M. I. Povolotskii, V. V. Negrebetskii, V. D. Romanenko, V. I.
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X-ray Crystallography: Crystallographic data were collected with a
Nonius Kappa CCD diffractometer with Mo-Kα radiation (graph-
ite monochromator, λ = 0.71073 Å) at 100 K. Crystallographic pro-
grams used for the structure solution and refinement were from
SHELXS-97,[19] SIR-97,[20] and SHELXL-97.[19] The structures
were solved by Direct Methods and were refined by using full-ma-
trix least squares on F2 of all unique reflections with anisotropic
thermal parameters for all non-hydrogen atoms. Hydrogen atoms
were included at calculated positions with U(H) = 1.2 Ueq for CH2
groups, U(H) = 1.5 Ueq for CH3 groups. Crystal data of the com-
pounds are listed in Table 1.[21]
[16] A. Marinetti, C. Charrier, F. Mathey, J. Fischer, Organometall-
ics 1985, 4, 2134–2138.
[17] G. Becker, O. Mundt, M. Rössler, E. Schneider, Z. Anorg. Allg.
Chem. 1978, 443, 42–52.
[1] Review: L. Weber, Eur. J. Inorg. Chem. 2000, 2425–2441.
[2] Ylides and Imines of Phosphorus (Ed.: A. W. Johnson), Wiley,
New York 1993.
[3] C. P. Casey, T. J. Burkhardt, J. Am. Chem. Soc. 1972, 94, 6543–
6544.
[18] H. Lecher, C. Heuck, Justus Liebigs Ann. Chem. 1924, 438,
179–184.
[19] G. M. Sheldrick, SHELX-97, program for crystal structure re-
finement, University of Göttingen, 1997.
[4] a) L. Weber, B. Quasdorff, H.-G. Stammler, B. Neumann,
Chem. Eur. J. 1998, 4, 469–475; b) L. Weber, M. Meyer, H.-G.
Stammler, B. Neumann, Chem. Eur. J. 2001, 7, 5401–5408; c)
L.Weber, M. Meyer, H.-G Stammler, B. Neumann, Organomet-
allics 2003, 22, 5063–5068.
[5] a) A. M. Arif, A. H. Cowley, C. M. Nunn, S. Quashie, N. C.
Norman, A. G. Orpen, Organometallics 1989, 8, 1878–1884; b)
E. Niecke, H. J. Metternich, M. Nieger, D. Gudat, P. Wender-
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[20] A. Altomare, M. C. Burla, M. Camalli, B. Carrozzini, G. L.
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[21] Further details of the crystal structure investigations are avail-
able. CCDC-256916 (3a), -255215 (3b), -255216 (4), -255214 (6)
and -255217 (10) contain the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif., together with the names
of the authors, and the journal citation.
[6] a) C. Hugel–Le Goff, F. Mercier, L. Ricard, F. Mathey, J. Or-
ganomet. Chem. 1989, 363, 325–335; b) F. Mercier, F. Mathey,
Organometallics 1990, 9, 863–864.
Received: December 1, 2004
1946
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
Eur. J. Inorg. Chem. 2005, 1940–1946