Developing click reactions of a 3-ferrocenyl-2H-azaphosphirene complex

Article abstract of DOI:10.1039/c0dt00730g

Atom efficient reactions of 3-ferrocenyl-2H-azaphosphirene complex 1 using a newly developed acid/base ring expansion protocol are presented. Consecutive reaction of 1 in the presence of dimethyl cyanamide with triflic acid and triethylamine yielded the s

Full text of DOI:10.1039/c0dt00730g

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www.rsc.org/dalton | Dalton Transactions
Developing click reactions of a 3-ferrocenyl-2H-azaphosphirene complex†
Rainer Streubel,*a Janaina Marinas Pe´rez,a Holger Helten,a Jo¨rg Danielsa and Martin Niegerb
Received 25th June 2010, Accepted 23rd September 2010
DOI: 10.1039/c0dt00730g
Atom efficient reactions of 3-ferrocenyl-2H-azaphosphirene complex 1 using a newly developed
acid/base ring expansion protocol are presented. Consecutive reaction of 1 in the presence of dimethyl
cyanamide with triflic acid and triethylamine yielded the selective formation of
2H-1,4,2-diazaphosphole complex 3. The same protocol using acetone, benzaldehyde and ferrocenyl
aldehyde afforded 1,3,5-oxazaphosphol-3-ene complexes 4, 5a,b and 6a,b, the latter as mixtures of
diastereomers, which could be separated. Apart from NMR, IR and UV/vis spectroscopic data, the
single-crystal X-ray structures of complexes 3, 4 and 6a are discussed.
respective ring system is protonated in the first reaction step,4–8
which leads to ring opening in the cases of 2H-azaphosphirene4
Introduction
and oxaphosphirane complexes.6,8 In the case of azaphosphiridine
complexes the protonated ring does not open up spontaneously,
but the P–N bond is activated towards the attack of electron-
rich nitriles.7 As we recently entered the attractive field of redox-
active complexes possessing one or two ferrocenyl groups9 in
order to investigate redox-switchable phosphorus heterocyclic
ligand systems, we decided to examine the applicability of this
methodology in this research area.
Here, reactions of a 3-ferrocenyl-2H-azaphosphirene complex
derivative I with a nitrile (to give II) and with ketones and aldehy-
des (to give III) are presented. In all cases an acid/base protocol
was applied to achieve the ring expansion of I thus providing
facile access to otherwise hard to access 1,3,5-oxazaphosphol-3-
ene complexes III.
The efficient construction of five-membered N-heterocycles such
as triazoles using click reactions1 has received increasing interest
during the last years since it usually follows a facile and reliable
protocol, e.g., [3+2] cycloaddition of azides and alkynes, and thus
can be applied to various fields of research.2
Recently, a novel and facile methodology for the ring expansion
of various three-membered P-heterocyclic ligands in the coordi-
nation sphere of group 6 transition metals such as tungsten was
developed. For example, ring expansion of 2H-azaphosphirene
complexes3 I leading to 2H-1,4,2-diazaphosphole complexes II4
(Scheme 1) was achieved via formal insertion of a nitrile into the
P–N bond of I using trifluoromethane sulfonic acid (CF3SO3H;
hereafter referred to as triflic acid or TfOH) and, subsequently, a
nitrogen base such as triethylamine.
Results and discussion
Insertion of a nitrile
When triflic acid was added to a solution of 2H-azaphosphirene
complex 19 in the presence of dimethyl cyanamide the initially red
colored reaction mixture turned immediately deep blue (Scheme 2)
Scheme 1 2H-Azaphosphirene complexes I and ring expansion products
II–IV ([M] denote a M(CO)5 moiety (M = Cr, Mo, W), R denote common
organic substituents, E denote sulfur and/or a NR group).
We recently demonstrated that the new concept can also be
applied to the atom efficient synthesis of a 2,3-dihydro-1,3-
azaphosphete and a 3H-1,3-azaphosphole complex via insertion
of an isonitrile or an alkyne, respectively.5 Furthermore, we
showed that it can easily be extended to oxaphosphirane6 and
azaphosphiridine7 complex chemistry, thus establishing this effi-
cient and modular method as new version of click chemistry in
the field of phosphorus heterocyclic chemistry for the first time.
Mechanistic studies revealed that the heteroatom (N or O) of the
aInstitut fu¨r Anorganische Chemie der Rheinischen Friedrich-Wilhelms-
Universita¨t Bonn, Gerhard-Domagk-Str., 1, 53121, Bonn, Germany. E-mail:
r.streubel@uni-bonn.de; Fax: +49 228 739616; Tel: +49 228 735345
bLaboratory of Inorganic Chemistry, Department of Chemistry University
of Helsinki, P.O. Box 55 (A.I. Virtasen aukio 1), FIN-00014, Finland
† CCDC reference numbers 777798 (3), 777321 (4) and 777322 (6a).
For crystallographic data in CIF or other electronic format see DOI:
10.1039/c0dt00730g
Scheme 2 Synthesis of 2H-1,4,2-diazaphosphole complex 3.
Dalton Trans., 2010, 39, 11445–11450 | 11445
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and the formation of complex 2 was evidenced by 31P NMR
spectroscopy in almost quantitative yield; 2 showed a resonance
at 102.6 ppm (|1JWP| = 253.0 Hz) with a phosphorus–proton
coupling constant magnitude of 22.9 Hz, which is character-
istic for N1-protonated 2H-1,4,2-diazaphospholium complexes
with an amidinium structural unit.4 Upon subsequent addition
of triethylamine the solution turned red again and 2H-1,4,2-
diazaphosphole complex 3 was selectively and quantitatively
formed. Complex 3 was purified by low-temperature column
chromatography and unambiguously characterized by multi-
nuclear NMR experiments, mass spectrometry, IR and UV/Vis
spectroscopy and a single-crystal X-ray diffraction study (Fig. 1);
the purity was examined by elemental analysis.
at 1991 cm-1, which can be assigned to normal modes of local
A1 and B1 symmetry, respectively. In the range of 1900–1950 cm-1
three very intense and partially overlapping bands appear, which
are attributable to vibrations of local A1 and E symmetry. Two
bands according to C–N stretch vibrations were observed at 1602
and 1550 cm-1.
The UV/Vis absorption spectrum of 3 shows a low-energy
transition at 404 nm that we assign, on the basis of recently
published results on related systems,10 to a metal–diazaphosphole
charge transfer (MLCT) process. A more intense p–p* absorption
appears at lmax = 296 nm. Another broad visible band appears
at lmax = 539 nm, which is assigned either to one or more nearly
degenerate d–d transitions of Fe(II),11 or to a metal–ligand charge
transfer process (dp–p*) occurring from the iron center to the
acceptor-substituted cyclopendadienyl ring.12,13 This assignment
is in accordance with the theoretical treatment (model III) by
Marder and coworkers.12
In the solid state the molecular structure of complex 3 shows an
essentially planar 2H-1,4,2-diazaphosphole ring (mean deviation
˚
from least-squares plane: 0.023 A), which is, to a large extent,
coplanar arranged with the adjacent Cp ring of the ferrocenyl
substituent. The twist angle with respect to least-squares planes is
only 18.1◦, and C1 of the Fc goup (i.e. C12) deviates only by
˚
0.007 A from the regression plane of the heterocyclic system.
The dimethylamino nitrogen atom is almost perfectly trigonal
planar coordinated (R < 360.0◦) and the plane of the NMe2 group
does not deviate significantly from the regression plane of the
diazaphosphole ring (deviations from least-squares plane: 0.015
˚
(N3), 0.058 (C10), and 0.032 A (C11)).
Insertion of carbonyl compounds
A long-standing challenge in phosphorus chemistry is the insertion
of unsaturated C–O p-systems into P–N bonds of free14,15 and/or
ligated phosphane derivatives,16 e.g., in the case of acyclic P(V)
compounds carbon dioxide was successfully inserted to yield cyclic
phosphacarbamates.17 Despite these efforts, aldehyde insertion
into P–N bonds of phosphazane derivatives had remained unsatis-
factory as insertion was always accompanied by Arbuzov-related
rearrangements to yield PV-oxides, instead.18 A recent report
demonstrated that exocyclic PIII–N bonds of cyclodiphosphazanes
are even more reactive than endocyclic bonds.19 Therefore, it
became even more interesting to examine the versatility of the new
acid-induced ring expansion protocol for ring expansion reactions
of 3-ferrocenyl-2H-azaphosphirene complex 1 with ketones and
aldehydes.
Fig. 1 Molecular structure of complex 3 in the crystal (hydrogen
atoms omitted for clarity; displacement parameters drawn at 50%
◦
˚
probability level). Selected bond lengths [A] and angles [ ]:W–C22
2.000(4), W–P 2.5359(8), P–N2 1.683(3), P–C1 1.859(3), C1–N1 1.292(4),
C2–N2 1.307(4), C2–N3 1.337(4), C1–C12 1.452(4), N2–P–C1 90.74(13),
P–C1–N1 110.7(2), C1–N1–C2 108.7(3), N1–C2–N2 120.5(3), C2–N2–P
109.0(2), N2–C2–N3 123.4(3).
Complex 3 displays a 31P resonance at 106.5 ppm, thus being
in the same range with the cationic complex 2. Compared to the
latter the tungsten–phosphorus coupling constant of 3 (241.6 Hz)
is about 11 Hz smaller. While the 13C resonance of the C3 center
When complex 1 in the presence of acetone was treated with
stoichiometric amounts of triflic acid in dichloromethane, 1,3,5-
oxazaphosphol-3-ene complex 4 was selectively obtained in almost
quantitative yield; in the case of benzaldehyde and ferrocenyl
aldehyde the formation of two diasteroisomers occurred (ratio
5a,b 63 : 37, 6a,b 87 : 13) (Scheme 3), which were separated
by low temperature chromatograpy, a standard procedure to
prevent/minimize decomposition on the solid phase.
appears at very low field (d = 206.5) and exhibits a |2+3
JPC| value of
26.8 Hz, the C5 center resonates at considerably higher field (d =
165.0) with no resolved coupling to phosphorus (see Scheme 2
for atom numbering). The NMe2 group gives rise to two sets
1
1
of distinctly different H and 13C resonances, thus pointing to
The 31P{ H} NMR resonances of complexes 4–6a,b were
a hindered rotation about the C5–NMe2 bond.
observed in the narrow range of 132–142 ppm with tungsten–
phosphorus coupling constant values of 269–281 Hz. In accor-
dance with the observations reported by us beforehand,20 it was
observed that the isomer with the downfield-shifted resonance
The C–O stretch vibration bands in the IR spectrum reflect
the slightly perturbed C4v symmetry of 3. It shows a single, well
separated band at 2071 cm-1 and another band with low intensity
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Scheme 3 Synthesis of 1,3,5-oxazaphosphol-3-ene complexes 4–6.
Fig. 2 Molecular structure of complex 4 in the crystal (hydrogen atoms
omitted for clarity, displacement parameter◦s drawn at 50% probability
has a smaller coupling constant in each case. The diastereomers
with 31P resonances at higher field show larger couplings with the
protons, which is increased in the case of the ferrocenyl derivatives
˚
level). Selected bond lengths [A] and angles [ ]: W1–P1 2.5121(6), P1–O1
1.6296(14), P1–C1 1.882(2), C1–N1 1.285(2), C2–O1 1.464(2), C2–N1
1.446(3), C1–C10 1.480(3), O1–P1–C1 89.04(8), P1–C1–N1 111.45(16),
C1–N1–C2 114.59(18), N1–C2–O1 108.88(15), C2–O1–P1 115.12(12).
1
5a,b and even more in 6a,b. The 13C{ H} NMR spectra showed
that the carbon atoms of the substituted cyclopentadienyl ring of
the C4-bonded ferrocenyl group are not equivalent. Instead of the
expected combined signal for Cp–C3/4 and Cp–C2/5, all carbons
have different values as a result of the hindered rotation about the
3
C–C axis. One of the ortho-carbon atoms shows a JPC coupling
and an unusually high chemical shift, while the other ortho-carbon
atom does not.
The IR spectra of complexes 4–5,6a,b show one strong band
in the carbonyl range (~ 1940–1950 cm-1) which is very broad,
most probably being the result of the overlapping of two IR active
bands, and another weak band at approximately 2070 cm-1 due to
the distorted octahedral symmetry of the M(CO)5 fragment.
The UV/vis spectra of the complexes 4–5, 6a,b show one lmax
at around 240 nm and shoulders that appear at lmax values around
466 nm.
The X-ray single-crystal structures of 4 and 6a unambiguously
confirmed the deduced regiochemistry of the ring enlargement
products (Fig. 2 and 3). In 4 the ferrocenyl substituent adopts a
cis position to the W(CO)5 group, which in 6a is changed to trans
and the two ferrocenyl substituents are cis oriented instead. The
bond lengths are very similar in complexes 4 and 6a and similar
to those reported before.20 The phosphorus–tungsten distance of
complexes 4 and 6a is shorter than that in 3, but in the normal
range for this kind of complexes. The heterocyclic rings in 4 and
6a are essentially planar, in both cases the oxygen atom points
out of the least-squares plane in an envelope configuration with
a small dihedral angle of 6.4◦ (4) and 7.8◦ (6a). The magnitude
of the torsion angles between the oxazaphospholene ring and the
Cp-ring of the Fc moiety depends on the substituent. If there
is only one Fc substituent the torsion angle is smaller (30.6◦ in
complex 4) than if there are two Fc groups (132.83◦ in complex
6a), the torsion angle of the other Cp ring bonded to C2 is
171.7◦.
Fig. 3 Molecular structure of complex 6a in the crystal (hydrogen
atoms omitted for clarity, displacement parameters drawn at 50%
◦
˚
probability level). Selected bond lengths [A] and angles [ ]: W1–P1
2.4973(7), P1–O1 1.6334(18), P1–C1 1.879(2), C1–N1 1.269(3), C2–O1
1.456(3), C2–N1 1.450(3), C1–C10 1.476(3), C2–C20 1.489(4), O1–P1–C1
88.75(10), P1–C1–N1 112.34(19), C1–N1–C2 113.5(2), N1–C2–O1
109.7(2), C2–O1–P1 114.06(14).
Conclusions
We have demonstrated that the newly developed acid/base pro-
tocol can be applied to the regioselective ring expansion of 3-
ferrocenyl-2H-azaphosphirene complex 1, thus enabling facile and
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efficient access to 2H-1,4,2-diazaphosphole complex 3 and 1,3,5-
oxazaphosphol-3-ene complexes 4, 5 and 6. This also illustrates
1) that P-coordination successfully prevented formation of PV-
oxides in the case of 4–6, which could have occurred otherwise,
and 2) that this efficient and modular protocol emerges as a new
powerful tool in phosphorus heterocyclic synthesis. Unfortunately,
due to the sensitivity of the compounds, a little bit more elaborate
purification is necessary than is typical in classic click reactions.
Current investigations aim at broadening the application using
other three-membered phosphorus heterocycles and various p-
substrates.
1602 m and 1550 w (CN); dH (C6D6) -0.02 (9 H, ssat, JSiH 6.5,
JCH 119.8, SiMe3), 0.36 (9 H, ssat, JSiH 6.5, JCH 119.1, SiMe3), 1.30
(1 H, d, JPH 7.9, CH(SiMe3)2), 2.83 (3 H, s, NMe), 2.95 (3 H, s,
NMe), 4.13 (5 H, s, Cp–CH unsubstit.), 4.21 (1 H, mc, Cp–C3/4
–
H), 4.24 (1 H, mc, Cp–C3/4H), 4.91 (1 H, mc, Cp–C2/5H), 5.10 (1
H, mc, Cp–C3/4H); dC (C6D6) 3.2 (dsat, JPC 2.3, JSiC 52.5, SiMe3),
3.6 (dsat, JPC 2.6, JSiC 53.1, SiMe3), 25.2 (d, JPC 10.0, CH(SiMe3)2),
37.6 (s, NMe), 37.6 (s, NMe), 70.5 (s, Cp–C3/4), 71.0 (s, Cp–C
unsubstit.), 71.1 (s, Cp–C3/4), 71.5 (s, Cp–C2/5), 75.6 (d, JPC 1.9,
Cp–C2/5), 79.9 (d, JPC 26.5, Cp–C1), 165.0 (s, PNC), 198.5 (dsat,
JWC 126.6, JPC 6.4, COcis), 199.8 (dsat, JWC 143.5, JPC 22.0, COtrans),
206.5 (d, JPC 26.8, PCN); dSi (C6D6) -0.1 (dsat, JPSi 7.3, JSiC 52.5),
1.6 (dsat, JPSi 3.5, JSiC 53.1); dP (C6D6) 106.5 (dsat, JWP 241.6, JPH
7.9); MS (FAB+, mNBA): m/z 779 ([M + H]+, 12%), 722 ([M –
Experimental
3CO]+, 30), 514 ((OC)5W(Me3Si)PC(H)SiMe3 , 24), 486 ([M + H
+
General procedures
– CH(SiMe3)2 – C10H15]+, 33), 455 ([M + H – W(CO)5]+, 100), 191
+
(Me3SiP(H)C(H)SiMe3 , 12).
All manipulations were carried out in an atmosphere of purified
and dried argon using standard Schlenk techniques. Solvents were
dried over sodium wire or CaH2 (CH2Cl2) and distilled under
argon. 2H-Azaphosphirene complex 19 was prepared according
to the method described in the literature. Triflic acid, dimethyl
cyanamide, benzaldehyde and ferrocenecarbonitrile were pur-
chased from Acros. Melting points were determined using a Bu¨chi
apparatus type S; the values are not corrected. Elemental analyses
were performed by using an Elementar VarioEL instrument.
UV/Vis absorption spectra were recorded on a Shimadzu UV-
1650 PC spectrometer (l = 190–1100 nm) from n-pentane solution
at ambient temperature and IR spectra were recorded as KBr
pellets using a Thermo Nicolet 380 FT-IR spectrometer. NMR
data were recorded on a Bruker Avance 300 spectrometer at 30 ◦C
using C6D6 or CDCl3 as solvent and internal standard; coupling
constants J are reported in Hz, chemical shifts in ppm relative
to tetramethylsilane (1H: 300.13, 13C: 75.5, 29Si: 59.6 MHz) and
85% H3PO4 (31P: 121.5 MHz). Mass spectra were recorded on a
Kratos Concept 1H (FAB+, mNBA) spectrometer or a MAT 95
XL Finnigan (EI, 70 eV, 184W) spectrometer (selected data given).
[5-Bis(trimethylsilyl)methyl-2,2-dimethyl-4-ferrocenyl-1,3,5-
oxazaphosphol-3-ene-jP]pentacarbonyltungsten(0) (4). To
a
stirred solution of 0.310 g (0.41 mmol) of 2H-azaphosphirene
complex 1 in 2 cm3 CH2Cl2 were added consecutively 88 mm3
(1.2 mmol) acetone and triflic acid (37 mm3, 0.41 mmol) at
ambient temperature. The initially red solution turned into a dark
solution. Subsequently, NEt3 (57 mm3, 0.41 mmol) was added at
ambient temperature while the reaction mixture turned red again.
Then the solvent was removed in vacuo and the product purified
by low temperature◦ column chromatography (SiO2, h = 10 cm,
f = 1 cm, T = -15 C) and eluted with a gradient of petroleum
ether/diethyl ether 100 to 95 : 5. The last fraction afforded the
dark red product after recrystallization from pentane (193 mg,
60%) as a red solid; m.p. 118 ◦C (Found: C, 39.9; H, 4.6; N, 1.6.
Calc. for C26H34FeNO6PSi2W: C, 39.9; H, 4.4; N, 1.7); lmax/nm
465 (e/dm3 mol-1 cm-1 1 202), 239 (189 700); nmax/cm-1 2071 m,
1964 m, 1931 s (CO); dH (300 MHz, CDCl3, SiMe4) -0.11 (9 H, s,
SiMe3), 0.30 (9 H, s, SiMe3), 1.30 (1 H, d, JPH 2.26, CH(SiMe3)2),
1.63 (3 H, s, Me), 1.73 (3 H, s, Me), 4.23 (5 H, s, Cp–CH unsubst.),
4.40 (2 H, m, Cp), 4.90 (1H, m, Cp), 4.95 (1 H, m, Cp–CH); dC
(75 MHz, CDCl3, SiMe4) 1.9 (dsat, JPC 1.9, SiMe3), 2.4 (dsat, JPC 2.6,
SiMe3), 27.5 (s, Me), 28.2 (s, Me), 36.7 (d, JPC 13.6, CH(SiMe3)2),
67.7 (s, Cp–C3/4), 68.5 (s, Cp–C5) 69.5 (s, Cp–C unsubst.), 74.5
(d, JPC 2.9, Cp–C2), 80.0 (d, JPC 33.6, Cp–C1), 111.3 (d, JPC 4.2,
POC), 171.0 (d, JPC 15.8, PCN), 196.5 (dsat, JPC 7.4, COcis), 198.3
(dsat, JPC 26.2, COtrans); dSi (60 MHz, CDCl3, SiMe4) -2.0 (dsat,
JPSi 9.8), 0.0 (dsat, JPSi 4.3); dP (121.5 MHz, CDCl3, H3PO4(85%))
138.8 (dsat, JWP 275.9, JPH 2.3); MS (EI, 70 eV, 184W, 140 ◦C): m/z
783 (M+, 60%), 727 ([M – 2CO]+, 12), 699 ([M – 3CO]+, 12%), 671
([M – 4CO]+, 18%) 6433 ([M – 5CO]+, 73%), 459 ([M – W(CO)5]+,
58), 253([FcCNCMe2]+, 100).
Preparation of 2H-1,4,2-diazaphosphole and
1,3,5-oxazaphos-phol-3-ene complexes
[2-Bis(trimethylsilyl)methyl-5-dimethyl-amino-3-ferrocenyl-2H-
1,4,2-diazaphosphole-jP]pentacarbonyl-tungsten(0) (3). To
a
stirred solution of 2H-azaphosphirene complex 1 (1.400 g, 1.93
mmol) in CH2Cl2 (35 cm3) were added consecutively dimethyl
cyanamide (170 mm3, 2.09 mmol) and triflic acid (170 mm3, 1.93
mmol) at ambient temperature. The initially red colored solution
turned deep blue. Subsequently, NEt3 (270 mm3, 1.92 mmol) was
added at ambient temperature while the reaction mixture turned
red again. After removement of all volatiles in vacuo (~1 Pa) the
crude product was dissolved in petroleum ether, filtered through
celite, and purified by column chromatography on silica (-35
◦C, 3 ¥ 10 cm) using petroleum ether/Et2O (10 : 1) as eluent.
Evaporation of the solvents of the first fraction (~1 Pa) yielded
[5-Bis(trimethylsilyl)methyl-2-phenyl-4-ferrocenyl-1,3,5-oxa-
zaphosphol-3-ene-jP]pentacarbonyltungsten(0) (5a,b). To
a
stirred solution of 0.310 g (0.41 mmol) of 2H-azaphosphirene
complex 1 in 2 cm3 CH2Cl2 were added consecutively 100 mm3
(1.0 mmol) benzaldehyde and triflic acid (37 mm3, 0.41 mmol) at
ambient temperature. The initially red solution turned into a dark
solution. Subsequently, NEt3 (57 mm3, 0.41 mmol) was added at
ambient temperature while the reaction mixture turned red again.
Then the solvent was removed in vacuo and the product purified
by low temperature column chromatography (SiO2, h = 10 cm,
◦
complex 3 (824 mg, 1.04 mmol, 54%) as a red solid; mp 147 C
(Found: C, 39.4; H, 4.3; N, 5.3. Calc. for C26H34FeN3O5PSi2W:
C, 39.3; H, 4.3; N, 5.3); lmax/nm 520 (e/dm3 mol-1 cm-1 1 544),
385sh (4 772), 352 (6 036), 300 (11 978), 252sh (39 209), 231 (65
176), 214sh (51 186); nmax/cm-1 2962w, 2930 w, 2905 w and 2876
w (CH3/CH), 2071 m, 1991 m, 1950 s, 1928 s and 1906 s (CO),
11448 | Dalton Trans., 2010, 39, 11445–11450
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◦
f = 1 cm, T = -15 C) and eluted with a gradient of petroleum
(121.5 MHz, CDCl3, H3PO4(85%)) 134.0 (ddsat, JWP 281.0, JPH 2.4,
◦
ether/diethyl ether 100 to 90 : 10. The second fraction yielded
complex 5b, and the third fraction yielded complex 5a (194 mg,
57%) as a red solid; m.p. 120 ◦C (Found: C, 43.7; H, 4.5; N, 1.5.
Calc. for C30H34FeNO6PSi2W: C,43.4; H, 4.1; N, 1.7); lmax/nm
468 (e/dm3 mol-1 cm-1 1 715), 246 (169 824); nmax/cm-1 2073 m,
1960 m, 1941 s, (CO); dH (300 MHz, CDCl3, SiMe4) 0.10 (9 H, s,
SiMe3), 0.30 (9 H, s, SiMe3), 1.50 (1 H, d, JPH 5.70, CH(SiMe3)2),
4.18 (5 H, s, Cp–CH unsubst.), 4.47 (2 H, mc, Cp), 5.03 (1 H,
mc, Cp), 5.09 (1 H, m, Cp), 6.89 (1H, d, JPH 1.8, CHPh), 7.45
(3H, m, Ph), 7.60 (2H, m, Ph); dC (75 MHz, CDCl3, SiMe4) 1.8
(dsat, JPC 1.9, SiMe3), 2.0 (dsat, JPC 2.6, SiMe3), 34.3 (d, JPC 18.1,
CH(SiMe3)2), 68.2 (s, Cp), 68.5 (s, Cp), 69.5 (s, Cp), 69.6 (s, Cp–C
unsubstit.), 74.5 (d, JPC 2.9, Cp), 76.8 (d, JPC 36.8, Cp–C1), 111.3
(d, JPC 4.2, POC), 125.2 (s, Ph), 127.5 (s, Ph), 127.9 (s, Ph) 128.7
(s, Ph), 133.4 (s, Ph), 13 (7.4 (d, JPC 4.2, i-Ph), 171.0 (d, JPC 15.8,
PCN), 196.5 (dsat, JPC 7.4, COcis), 198.3 (dsat, JPC 26.2, COtrans); dSi
(60 MHz, CDCl3, SiMe4) -2.1 (dsat, JPSi 9.8), 0.1 (dsat, JPSi 4.3);
dP (121.5 MHz, CDCl3, H3PO4(85%)) 1◦34.5 (ddsat, JWP 281.0, JPH
1.8, JPH 5.7). MS (EI, 70 eV, 184W, 140 C): m/z 831 (M+, 47%),
747 ([M – 3CO]+, 40%), 719 ([M – 4CO]+, 10%), 691 ([M – 5CO]+,
56%), 507 ([M – W(CO)5]+, 73), 253([FcCNCHPh]+, 100).
JPH 5.1). MS (EI, 70 eV, 184W, 140 C): m/z 939 (M+, 29%), 855
([M – 3CO]+, 10%), 799 ([M – 5CO]+, 27%), 615 ([M – W(CO)5]+,
60), 409 ([FcCNCHFc]+, 100).
Complex 6b. (35 mg, 9%) dH (300 MHz, CDCl3, SiMe4) -0.04
(9 H, s, SiMe3), 0.09 (9 H, s, SiMe3), 1.43 (1 H, d, JPH 8.9,
CH(SiMe3)2), 4.22 (1 H, m, Cp), 4.25 (2 H, m, Cp), 4.31 (5 H, s,
Cp–CH unsubst.), 4.34 (5 H, s, Cp–CH unsubst.), 4.45 (2H, m,
Cp), 4.50 (1 H, m, Cp), 4.92 (1 H, m, Cp), 4.95 (1H, m, Cp), 6.93
(1H, d, JPH 5.28, CHFc); dP (121.5 MHz, CDCl3, H3PO4(85%))
140.3 (ddsat, JWP 270.8, JPH 5.3, JPH 8.9).
X-ray crystallography
X-ray crystallographic analyses of 3, 4 and 6a: Suitable red single
crystals were obtained from concentrated diethyl ether (3) and
pentane (4,6a) solutions upon decreasing the temperature from
ambient temperature to +4 ◦C. Data were collected on a Nonius
KappaCCD diffractometer equipped with a low-temperature de-
vice (Cryostream, Oxford Cryosystems) at 293 (3) or 123 K (4,6a)
˚
using graphite monochromated Mo-Ka radiation (l = 0.71073 A).
The structures were solved by Patterson methods (SHELXS-97)21
and refined by full-matrix least squares on F2 (SHELXL-97).21 All
non-hydrogens were refined anisotropically. The hydrogen atoms
were localized by difference electron density determination and
refined isotropically using the riding model on the bound atoms.
Absorption corrections were carried out analytically (3) or semi-
empirically from equivalents (4,6a) (min./max. transmissions =
0.2203/0.5090 (3), 0.48199/0.53633 (4) and 0.36587/0.53554 (6a).
Complex 5b. (35 mg, 10%) dH (300 MHz, CDCl3, SiMe4) -0.11
(9 H, s, SiMe3), 0.08 (9 H, s, SiMe3), 1.34 (1 H, d, JPH 6.40,
CH(SiMe3)2), 4.31 (5 H, s, Cp–CH unsubstit.), 4.40 (2 H, m, Cp),
5.81 (1 H, m, Cp), 6.00 (1 H, m, Cp), 6.98 (1H, d, JPH 3.21,
CHPh), 7.45 (3H, m, Ph), 7.55 (2H, m, Ph); dP (121.5 MHz, CDCl3,
H3PO4(85%)) 142.1 (ddsat, JWP 269.6, JPH 3.3, JPH 6.4).
[5-Bis(trimethylsilyl)methyl-2,4-bisferrocenyl-1,3,5-oxazaphos-
phol-3-ene-jP]pentacarbonyltungsten(0) (6a,b). To a stirred so-
lution of 0.310 g (0.41 mmol) of 2H-azaphosphirene complex 1
in 2 cm3 CH2Cl2 were added consecutively 0.256 g (1.2 mmol)
ferrocenyl aldehyde and triflic acid (37 mm3, 0.41 mmol) at ambient
temperature. The initially red solution turned into a dark solution.
Subsequently, NEt3 (57 mm3, 0.41 mmol) was added at ambient
temperature while the reaction mixture turned red again. Then
the solvent was removed in vacuo and the product purified by low
temperature column chromatography (SiO2, h = 10 cm, f = 1 cm,
T = -15 ◦C) and eluted with a gradient of petroleum ether/diethyl
ether 100 to 95 : 5. The second fraction yielded complex 6b thus
the third fraction yielded complex 6a.
Crystal structure data for complex 3 (C26H34FeN3O5PSi2W).
Crystal size 0.50 ¥ 0.18 ¥ 0.18 mm, monoclinic, P21/n, a =
˚
16.0145(5), b = 12.3033(4), c = 16.1955(3) A, b = 103.387(2),
V = 3104.31(15) A , Z = 4, rc = 1.702 Mg m , 2qmax = 55◦,
collected (independent) reflections = 21506 (6845), Rint = 0.0336,
m = 4.337 mm-1, 387 refined parameters, 0 restraints, R1 (for I >
2s(I)) = 0. 0.257, wR2 (for all data) = 0.0613, S = 1.051, max./min.
3
-3
˚
-3
˚
residual electron density = 3.694/- 1.404 e A .
Crystal structure data for complex 4 (C26H34FeNO6PSi2W).
Crystal size 0.20 ¥ 0.18 ¥ 0.16 mm, monoclinic, P21/c, a =
Complex 6a. (238 mg, 62%) as a orange solid; mp 125 ◦C
(Found: C, 43.1; H, 4.4; N, 1.5. Calc. for C34H38Fe2NO6PSi2W: C,
43.4; H, 4.1; N, 1.5); lmax/nm 466 (e/dm3 mol-1 cm-1 1 544), 240
(65 176); nmax/cm-1 2073 m, 1960 m, 1943 s (CO); dH (300 MHz,
CDCl3, SiMe4) 0.05 (9 H, s, SiMe3), 0.30 (9 H, s, SiMe3), 1.40
(1 H, d, JPH 5.09, CH(SiMe3)2), 4.17 (5 H, s, Cp–CH unsubst.),
4.25 (2 H, m, Cp), 4.30 (5 H, s, Cp–CH unsubst.), 4.32 (1 H, s,
Cp), 4.41 (1 H, m, Cp), 4.44 (2 H, m, Cp), 4.99 (1H, m, Cp), 5.02
(1H, m, Cp), 6.84 (1H, d, JPH 2.36, CHFc); dC (75 MHz, CDCl3,
SiMe4) 1.8 (dsat, JPC 1.9, SiMe3), 2.0 (dsat, JPC 2.6, SiMe3), 33.1 (d,
JPC 9.1, CH(SiMe3)2), 65.2 (s, Cp), 65.3 (s, Cp), 65.4 (s, Cp), 67.5
(s, Cp), 67.6 (s, Cp), 68.0 (s, Cp-unsubst.), 68.1 (s, Cp), 68.3 (s,
Cp), 69.0 (s, Cp), 69.4 (s, Cp-unsubst), 74.3 (d, JPC 2.6, Cp), 79.0
(d, JPC 34.3, Cp-C1), 106.1 (d, JPC 5.8, POC), 171.0 (d, JPC 16.6,
PCN), 196.2 (dsat, JPC 7.4, COcis), 198.0 (dsat, JPC 26.2, COtrans); dSi
(60 MHz, CDCl3, SiMe4) -2.3 (dsat, JPSi 10.0), 0.0 (dsat, JPSi 4.3); dP
◦
˚
11.7925(1), b = 12.2414(1), c = 21.4230(3) A, b = 98.969(1) ,
V = 3054.74(6) A , Z = 4, rc = 1.703 Mg m-3, 2qmax = 55◦,
3
˚
collected (independent) reflections = 17330 (6866), Rint = 0.0347,
m = 4.407 mm-1, 343 refined parameters, R1 (for I > 2s(I)) = 0.
0202, wR2 (for all data) = 0.0449, S = 1.033, max./min. residual
-3
˚
electron density = 0.772/- 0.678 e A .
Crystal structure data for complex 6a (C34H38Fe2NO6PSi2W).
Crystal size 0.35 ¥ 0.25 ¥ 0.15 mm, orthorhombic, Pccn, a =
˚
18.8898(2), b = 28.5021(3), c = 13.8338(1) A, V = 7448.10(12)
A , Z = 8, rc = 1.675 Mg m , 2qmax = 55◦, collected (independent)
reflections = 37905 (8475), Rint = 0.0517, m = 4.00 mm-1, 424 refined
parameters, R1 (for I > 2s(I)) = 0. 0262, wR2 (for all data) = 0.0532,
S = 0.927, max./min. residual electron density = 1.231/- 1.754 e
3
-3
˚
-3
˚
A .
This journal is
The Royal Society of Chemistry 2010
Dalton Trans., 2010, 39, 11445–11450 | 11449
©

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8 J. Marinas Pe´rez, H. Helten, B. Donnadieu, C. A. Reed and R. Streubel,
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Acknowledgements
Financial support by the DFG (STR 411/25-2), the COST action
CM0802 “PhoSciNet” and the Fonds der Chemischen Industrie
(Kekule´ grant for H. Helten) is gratefully acknowledged.
Notes and references
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11450 | Dalton Trans., 2010, 39, 11445–11450
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The Royal Society of Chemistry 2010
©