Cumulenylidene and acetylide complexes accessed via stannylated acetylenes and butadiynes

Article abstract of DOI:10.1021/om100702x

The tungsten butatrienylidenes [cis-W(CO)(dppe)₂{C=C=C=C(R) (SnMe₃)}] (R = SnMe₃ (2) and SiMe₃ (3); dppe = 1,2-bis(diphenylphosphinoethane)) were prepared from the reactions of [trans-W(CO)(N₂)(dppe)<

Full text of DOI:10.1021/om100702x

Organometallics 2010, 29, 6321–6328 6321
DOI: 10.1021/om100702x
[W(CO)(dppe)2] Cumulenylidene and Acetylide Complexes Accessed
via Stannylated Acetylenes and Butadiynes
Sergey N. Semenov, Olivier Blacque, Thomas Fox, Koushik Venkatesan, and Heinz Berke*
Department of Inorganic Chemistry, University of Zu€rich, Winterthurerstrasse 190, 8057 Zu€rich,
Switzerland
Received July 16, 2010
The tungsten butatrienylidenes [cis-W(CO)(dppe)2{CdCdCdC(R)(SnMe3)}] (R=SnMe3 (2) and
SiMe3 (3); dppe=1,2-bis(diphenylphosphinoethane)) were prepared from the reactions of [trans-
W(CO)(N2)(dppe)2] (1) and the respective butadiynes displaying a 1,4-shift of the respective SnMe3
groups along the butadiyne chains. Stannyl deprotection of 2 with NBu4F 3H2O led to the anionic
3
butadiyne derivative [trans-W(CO)(dppe)2(CtCCtCH)][NBu4] (10). The reaction of 1 with stan-
nylated acetylenes gave the vinylidene derivatives [cis-W(CO)(dppe)2{CdC(SnMe3)(R)}] (R=Ph (5)
or SnMe3 (6)), which lost a SnMe3 group, yielding W(I) acetylides of the type [trans-W(CO)(dppe)2-
(CtCR)] (R=Ph (7), SnMe3 (8), and SiMe3 (9)). They were studied by cyclic voltammetry and EPR
spectroscopy.
Introduction
(dmpe=1,2-bis(dimethylphosphinoethane))11,12 revealed bond
length alternation along the cumulenylidene chain. The lon-
gest terminal cumulenic chain was found in the C7 compound
[M(CO)5{CdCdCdCdCdCdC(NMe2)2)}] (M=Cr, W).13
Other types of group 6 metal centers were also shown to sta-
bilize long-chain cumulenylidenes.14 Thus, recently C4 tung-
sten complexes [cis-W(CO)(dppe)2{CdCdCdC(R)( p-C6H4-
tBu)}] (R=SnMe3 or H) were reported.15 The preparation of
butatrienylidenes often starts from terminal diynes involving
1,4-H shifts; however 4-H-butatrienylidenes proved to be unsta-
ble. We found that topologically related 1,4-SnMe3 shifts may
be utilized to circumvent the often too reactive H-substituted
cumulenylidenes.
Cationic ruthenium complexes containing a [Ru(CdCd
CdCdCRH)]þ fragment were prepared in situ (R=H) by
Bruce16 (R¼ H), Dixneuf,17 and Winter.17 They found a variety
of typical reactions based on nucleophilic attack at Cγ and
subsequent cycloaddition. The [2 þ 2] addition between the
Ru cumulene and butadiyne derivatives led to binuclear
Metallacumulenes [LxMdC(dC)nRR0] possess a high de-
gree of unsaturation, which makes these compounds unique
candidates for application as materials with special electronic
and NLO (nonlinear optical) properties.1,2 Related binuclear
cumulene complexes revealed a high degree of delocalization
of the unpaired electron in mixed valence species.3,4 While
compounds with vinylidenes :CdCRR0 and allenylidenes :
CdCdCRR0 as cumulenic ligands are quite common,1,5 re-
ports on the existence of butatrienylidenes and pentatetra-
enylidenes of the type [LxM(CdCdCdCRR0)] and [LxM-
(dCdCdCdCdCRR0)] are very rare. X-ray diffraction studies
of the fairly stable species [Cl(PiPr3)2IrdC(dC)n(Ph)2] (n=
3, 4),6-8 [Cl(dppe)2Ru(CdCdCdC=CPh2)] (dppe=1,2-bis-
(diphenylphosphinoethane)),9 [W(CO)5{CdCdCdCdC-
(NMe2)2}],10 and [(Cp)(dmpe)Mn{CdCdCdC(SnPh3)2}]
*To whom correspondence should be addressed. E-mail: hberke@
aci.uzh.ch.
(1) Bruce, M. I. Chem. Rev. 1998, 98, 2797.
(2) (a) Bruce, M. I. Coord. Chem. Rev. 2004, 248, 1603. (b) Cadierno,
V.; Gimeno, J. Chem. Rev. 2009, 109, 3512.
(10) (a) Roth, G.; Fischer, H. Organometallics 1996, 15, 1139. (b) Roth,
G.; Fischer, H.; Meyer-Friedrichsen, T.; Heck, J.; Houbrechts, S.; Persoons, A.
Organometallics 1998, 17, 1511.
(3) (a) Unseld, D.; Krivykh, V. V.; Heinze, K.; Wild, F.; Artus, G.;
Schmalle, H.; Berke, H. Organometallics 1999, 18, 1525. (b) Venkatesan, K.;
Fox, T.; Schmalle, H. W.; Berke, H. Organometallics 2005, 24, 2834. (c) Rigaut,
S.; Massue, J.; Touchard, D.; Fillaut, J. L.; Golhen, S.; Dixneuf, P. H. Angew.
Chem., Int. Ed. 2002, 41, 4513. (d) Rigaut, S.; Le Pichon, L.; Daran, J. C.;
Touchard, D.; Dixneuf, P. H. Chem. Commun. 2001, 1206. (e) Rigaut, S.;
Olivier, C.; Costuas, K.; Choua, S.; Fadhel, O.; Massue, J.; Turek, P.; Saillard,
J. Y.; Dixneuf, P. H.; Touchard, D. J. Am. Chem. Soc. 2006, 128, 5859.
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Chem. 2005, 901.
(11) Venkatesan, K.; Fernandez, F. J.; Blacque, O.; Fox, T.; Alfonso,
M.; Schmalle, H. W.; Berke, H. Chem. Commun. 2003, 2006.
(12) Venkatesan, K.; Blacque, O.; Fox, T.; Alfonso, M.; Schmalle,
H. W.; Berke, H. Organometallics 2004, 23, 4661.
(13) Dede, M.; Drexler, M.; Fischer, H. Organometallics 2007, 26,
4294.
(14) Fischer, H.; Szesni, N. Coord. Chem. Rev. 2004, 248, 1659.
(15) Semenov, S. N.; Blacque, O.; Fox, T.; Venkatesan, K.; Berke, H.
Angew. Chem., Int. Ed. 2009, 48, 5203.
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B. W.; White, A. H. Chem. Commun. 1997, 715. (b) Bruce, M. I.;
Hinterding, P.; Low, P. J.; Skelton, B. W.; White, A. H. J. Chem. Soc.,
Dalton Trans. 1998, 467. (c) Bruce, M. I.; Hinterding, P.; Low, P. J.; Skelton,
B. W.; White, A. H. Chem. Commun. 1996, 1009.
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Eur. J. 1996, 2, 19.
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(17) (a) Haquette, P.; Touchard, D.; Toupet, L.; Dixneuf, P. J. Organo-
met. Chem. 1998, 565, 63. (b) Winter, R. F.; Hornung, F. M. Organometallics
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r
2010 American Chemical Society
Published on Web 11/15/2010
pubs.acs.org/Organometallics

6322 Organometallics, Vol. 29, No. 23, 2010
Semenov et al.
Scheme 1
Table 1. IR, NMR, and UV-Vis Data of Complexes 2, 3, and 4
absorption [nm]
(ε/1000 [M-1 cm-1])
IR [cm-1
]
NMR 13C [ppm]
ν
ν
(C4) (CO) CR
Cβ
Cγ Cδ
λ1
λ2
λ3
2
3
1925 1808 249.5 124.8 124.7 46.8 376 (29.6) 466 (4.9) 900 (4.4)
1940 1803 254.1 142.4 142.5 49.1 373 (37.4) 468 (5.2) 899 (2.2)
4a 1935 1798 267.6 162.6 140.0 70.7 386 (163) 525 (82) 768 (0.7)
a Data from ref 15.
complexes possessing a cyclobutene bridge.18 The related dimer-
ization of tungsten butatrienylidene is another rare example
of relatively clean self-coupling.15 In this work we approached
the deprotection of SnMe3-substituted derivatives generat-
ing the parent tungsten butadiyne complexes.
On the short chain side there would be tin-substituted vinyl-
idenes, which could undergo chain extension by Stille-type
coupling reactions. Up to now mainly tin-substituted man-
ganese vinylidene derivatives were explored,4,19 which is now
extended to tin-substituted tungsten vinylidenes.
Results and Discussion
Synthesis and Structural Studies on Tungstenacumulenes.
Butatrienylidene complexes were obtained via primary addi-
tion and π binding of 1,4-butadiyne tin derivatives to coor-
dinatively unsaturated electron-rich metal centers. These systems
subsequently rearrange to end-on butatrienylidene complexes.
For the preparation of tungsten complexes [trans-W(CO)-
(N2)(dppe)2] (1) was chosen as the metal precursor, offering
for ligand exchanges the labile N2 ligand.20,21 The four elec-
tron-donating dppe ligands were anticipated to create a pro-
nounced preference for “end-on” cumulenylidene ligands via
enhanced back-donation, stabilizing the binding of this highly
unsaturated ligand.
1 reacts with Me3SnCtCCtCR derivatives15 (Scheme 1)
with heating, and repeated removal of N2 in vacuo enabled
the binding of the butadiyne ligand accompanied by a 1,4-
SnMe3-shift and formation of the butatrienylidene derivative.
The bis-stannylated product [cis-W(CO)(dppe)2{CdCd
CdC(SnMe3)2}] (2) was isolated as very air sensitive crystals
in 72% yield. A cis-position of the diphosphines was indicated
in the 31P NMR spectra, showing two doublets of multiplets
(JP-P=100 Hz) originating from coupling with the trans phos-
phorus atoms and two multiplets for the phosphorus atoms
located trans to CO and trans to the C4 chain. This assign-
ment was confirmed by a COSY experiment. The 13C NMR
spectra of 2showed four resonances for the C4 cumulenic chain
at 249.5 (CR), 124.9 (Cβ), 124.8 (Cγ), and 46.8 ppm (Cδ). All
Figure 1. Thermal ellipsoid plots of the structures of 2 (top) and
3 (bottom) (30% probability level). Hydrogen atoms and sol-
vent molecules are omitted for clarity.
four signals are shifted to high field with respect to the related
species [cis-W(CO)(dppe)2{CdCdCdC(SnMe3)(p-C6H4tBu)}]
(4) (Table 1). The 119Sn NMR spectrum of 2 shows Sn-P
coupling for the unique signal at -22.5 ppm. A typical ν(CtO)
band is observed at 1786 cm-1, as well as a ν(C4) vibration at
1926 cm-1. The position of these bands is similar to those of
the previously reported [cis-W(CO)(dppe)2(CdCHR)] and [Ir
(Cl)(PiPr3)2(CdCdCdCPh2)].6,7,22
The spectroscopically derived structure of 2 was finally
confirmed by X-ray structural analysis (Figure 1). Details of
the data collection and refinement are presented in Tables 1S
and 2S, and selected bond lengths are reported in Table 2.
The unsaturated carbon chain slightly deviates from line-
arity at C2 with a C1-C2-C3 angle of 170.6°. The lengths of
the C2-C3 and C4-C5 double bonds are longer (1.305(5)
˚
˚
and 1.307(5) A) than the internal C3-C4 bond (1.285(5) A).
This behavior is significantly different from the reported Ir-
C4 and Mn-C4 cumulenic species, where the CR-Cβ and Cγ-
Cδ lengths are short and the Cβ-Cγ length is longer.6,11 The
(18) Bruce, M. I.;Ellis, B. G.;Skelton, B. W.;White, A. H. J. Organomet.
Chem. 2005, 690, 1772.
(19) Venkatesan, K.; Blacque, O.; Fox, T.; Alfonso, M.; Schmalle,
H. W.; Kheradmandan, S.; Berke, H. Organometallics 2005, 24, 920.
(20) Ishida, T.; Mizobe, Y.; Tanase, T.; Hidai, M. J. Organomet.
Chem. 1991, 409, 355.
˚
WdC bond distance of 2 of 1.937(4) A is slightly longer than
˚
that observed for 4 (1.923(3) A), presumably indicating weaker
(22) Nakamura, G.; Harada, Y.; Mizobe, Y.; Hidai, M. Bull. Chem.
Soc. Jpn. 1996, 69, 3305.
(21) Ishida, T.; Mizobe, Y.; Tanase, T.; Hidai, M. Chem. Lett. 1988, 441.

Article
Organometallics, Vol. 29, No. 23, 2010 6323
Table 2. Selected Average Bond Lengths of Compounds 2-5, 7,
and 9a
W-Pb
W-CO
W-CR
CR-Cβ
Cβ-Cγ
Cγ-Cδ
2
2.5054(6) 1.961(3) 1.937(3) 1.305(4) 1.285(4) 1.307(4)
3c 2.505(2)
1.98(1) 1.93(1) 1.31(1) 1.27(1) 1.32(1)
4d 2.5205(8) 1.937(3) 1.923(3) 1.306(4) 1.273(4) 1.325(4)
5
7
9
2.509(1)
1.940(5) 2.007(4) 1.298(6)
2.4718(5) 2.041(3) 2.207(2) 1.158(3)
2.4783(7) 2.019(4) 2.153(3) 1.204(3)
a Assignment of the bond lengths in the C4 and C2 chains according to
the following notation: [W]CRCβCγCδ. b An average value of the four
W-P bonds is presented. c An average value for two crystallographically
independent molecules of 3 is presented. d Data from ref 15.
Scheme 2
Figure 2. Thermal ellipsoid plot of the structure of 6 (30% prob-
ability level). Hydrogen atoms and solvent molecules are omitted
for clarity.
The vinylidene complex [cis-W(CO)(dppe)2{CdC(SnMe3)-
(Ph)}] (5) could eventually be isolated by crystallization from
benzene/pentane in the dark. The structure of 5 was fully
established by 1H, 13C, and 31P NMR spectroscopy and ele-
mental analysis. The 31P NMR spectrum revealed the tung-
sten environment to be analogous to 2and 3with cis-configured
diphosphines, and in addition the 13C NMR spectrum of 5
exhibited resonances for the vinylidene unit at 309 (CR) and
111.6 ppm (Cβ), which were comparable to the data of other
tungsten vinylidenes.22,23 The reaction of 1 applying Me3Sn-
CtCSnMe3 afforded the bis-trimethylstannyl-substituted
vinylidene complex [cis-W(CO)(dppe)2{CdC(SnMe3)2}] (6) in
30% yield. The structure of 6 was established by spectroscopic
methods and confirmed by an X-ray diffraction study (Figure 2).
The [cis-W(CO)(dppe)2] substructure of 6 is overall similar
π-acceptor properties of the C4 chain of 2 relative to the one
with aromatic substituent.
The stannyl acetylene method was used to access asymmet-
rically substituted butatrienylidene complexes. Applying 1 in
the reaction with Me3SnCtCCtCSiMe3, the compound
[cis-W(CO)(dppe)2{CdCdCdC(SnMe3)(SiMe3)}] (3) was
formed, which could be isolated in 62% yield. Like 2, 3 revealed
cis-diphosphines, established via 31P NMR spectroscopy
showing four resonances and the expected coupling patterns.
The 13C NMR spectra of 3 exhibited butatrienylidene reso-
nances slightly shifted to low field with respect to the bis-
trimethyltin-substituted derivative at 254.1 (CR), 142.4 (Cβ),
142.5 (Cγ), and 49.1 ppm (Cδ). In general, the 13C NMR data
of the tungsten C4 cumulenes 2-4 turned out to be quite
comparable to those of the MnC4 series except for the Cδ
signals, which are located at lower field.11,12 The 119Sn NMR
spectrum of 3 showed a signal similar to 2 at -26.1 ppm. It
was simulated using the following 119Sn, 31P coupling constan-
cies: 27.6, 42.3, 44.1, and 59.3 Hz. The crystal structure of 3
was determined from crystals grown from a toluene/pentane
mixture. The unit cell contains two independent molecules.
The bond alternation of the C4 chain in the independent mole-
cules was found to be similar to 2. In both 2 and 3 molecules
the W-CO axis is orthogonal to plane of the terminal CSnSn
or CSnSi fragment. This could be rationalized on the basis of
the idea that the empty p orbital of CR prefers to be perpen-
dicular to W-CO since it is not concurrent with CO in back-
bonding. The double-bond alternation will lead to the observed
orientation of the W-CO axis relative to the terminal fragment.
Trimethyltin acetylenes were expected to react in a manner
analogous to the diynes, producing via a shift of the stannyl
group trimethyltin-substituted vinylidenes. The reaction of 1
with Me3SnCtCPh was carried out under conditions similar
to those for 2, monitoring the progressing reaction by 31PNMR
spectroscopy (Scheme 2).
˚
to that of 2 and 3. The WdC bond distance of 2.007(4) A is
longer than that observed for related vinylidene species [cis-
W(CO)(dppe)2(CdCHCOOEt)] (1.88(1) A)22,24 and is slightly
˚
longer than the WdC bond distance in the butatrienylidene
complex 2. This is in line with the theoretical prediction of
increasing π-acceptor properties with an increase in the num-
ber of cumulenic carbon atoms.25 The formation of vinylidene
derivatives directly from 1 and tin-substituted acetylenes is in
contrast to the reactivity of terminal acetylenes, where the
required acetylene/vinylidene rearrangement was not acces-
sible; rather the alternative pathways of C-H oxidative addi-
tions prevailed.22
The reaction of 1 with Me3SnCtCSiMe3 furnished also a
vinylidene derivative, which could be detected by NMR in
solution, but could not be isolated due to its too low stability.
The main product of this reaction was [trans-W(CO)(dppe)2-
(CtC-SiMe3)] (9). In a similar fashion loss of the tin group
occurred for 6 and 5, producing [trans-W(CO)(dppe)2(CtC-
SnMe3)] (8), phenylacetylide complex [trans-W(CO)(dppe)2-
(CtCPh)] (7), andMe3SnSnMe3. The yields of 5 and 6 accord-
ing to Scheme 2 are low, because even in thermally induced
reactions they are intermediates on the way to 7 and 8. Full
conversions of 5 and 6 to 7 and 8 could be accomplished by
(23) Birdwhistell, K. R.; Burgmayer, S. J. N.; Templeton, J. L. J. Am.
Chem. Soc. 1983, 105, 7789.
(24) Marrone, A.; Re, N. Organometallics 2002, 21, 3562.
(25) Re, N.; Sgamellotti, A.; Floriani, C. Organometallics 2000, 19,
1115.

6324 Organometallics, Vol. 29, No. 23, 2010
Semenov et al.
short periods of UV irradiation. The photolytic activation of
the tin-substituted vinylidenes is expected to operate on the
same basis as the thermal processes breaking the C-Sn bond
with subsequent recombination of the SnMe3 radical to form
Me3SnSnMe3. The remaining radical on the β-carbon atom
delocalizes to the tungsten center with structures best de-
scribed as W(I) acetylide complexes. All three compounds
7-9 are paramagnetic d5 species and are related in the way of
their formation to dinuclear tungsten acetylide complexes re-
cently obtained in our group.15 7 and 9 were characterized by
single-crystal X-ray diffraction analyses (Figure 3 and Sup-
porting Information).
ligands and identical to one of the singlets of the VT NMR.26
The 13C NMR spectrum shows four signals for the C4 car-
bon atoms at 149.2 (CR), 98.9 (Cβ), 76.8 (Cγ), and 48.7 ppm
(Cδ). A DEPT experiment confirmed that Cδ is bonded to one
1
proton. The H NMR spectrum also clearly demonstrated
the presence of the [NBu4]þ cation. On the basis of these data
the pseudo-octahedral structure [trans-W(CO)(dppe)2(CtC-
CtCH)][NBu4] (10) was proposed, which could be con-
firmed by an X-ray diffraction analysis (Figure 4). 10 is pre-
sumably formed via consecutive destannylation of 2 with
[trans-W(CO)(dppe)2(CtCCtCSnMe3)][NBu4] as an inter-
mediate, which was attributed the second singlet appearing
in the VT 31P NMR spectra.
The coordinative environment of the tungsten center in 9 is
pseudo-octahedral, composed of a square of phosphorus atoms
(trans diphosphines) and trans-disposed CO and alkynyl li-
Spectroscopic and Electrochemical Properties. The buta-
trienylidene complexes 2-4 were characterized by UV-vis-
NIR and CV (cyclic voltammetry) studies. The UV-vis-
NIR data are presented in Figure 5.
˚
gands. Average W-P distances of 2.472(1) and 2.478(1) A
were found for 7 and 9, respectively.
We then attempted the deprotection of 2 by treatment with
a THF water solution in a similar way to that for 4;15 how-
ever a complex mixture was obtained that could not be fully
unraveled into its components. To gain further insight into
this transformation, a low-temperature study of the reaction
All three complexes 2-4 exhibit three main absorptions.
Their intensities decrease with increasing wavelengths (Table 1).
The lowest energy transition could be attributed to the HOMO/
LUMO transition. The p-tBuC6H4 substituent turns out to
be a special case in this series of spectra, because this substit-
uent strongly affects both the position and intensities of the
absorptions (Figure 5), while the change of the SnMe3 to a
SiMe3 substituent has only little influence on the spectra. As
could be seen from the spectra, the band for 4 reveals a strong
blue shift and decreases in intensity. This could imply an
increase in the HOMO-LUMO gap, which would be con-
sistent with the higher stability of the deprotected complex
bearing an aromatic substituent.
between 2 and NBu4F 3H2O was initiated and monitored by
3
1H and 31P NMR spectroscopy. We found no evidence for
the formation of a H-substituted cumulenylidene complex, even
at low temperature (-40 °C). Instead two overlapping sin-
glets were detected in the 31P NMR spectrum, remaining at
room temperature, but changing in intensities during the course
of the reaction. The reaction mixture was evaporated to dry-
ness, and the solid residue was washed with toluene to give an
orange powder of complex 10 (Scheme 3). This compound
showed a singlet in the 31P NMR spectrum with a chemical
shift similar to other complexes with trans-disposed dppe
CV studies of 2 and 4 revealed irreversible oxidation and
reduction processes (see Supporting Information for details).
Figure 4. Thermal ellipsoid plot of the structure of the anionic
part of 10 (30% probability level). The tetrabutylammonium
cation and selected hydrogen atoms are omitted for clarity. Only
one of the two crystallographically independent molecules is
presented.
Figure 3. Thermal ellipsoidplot of the structureof 9 (30% proba-
bility level). Hydrogen atoms and solvent molecules are omitted
for clarity.
Scheme 3

Article
Organometallics, Vol. 29, No. 23, 2010 6325
Figure 5. UV-vis-NIR spectra for 2 (orange), 3 (blue), and
4 (red).
Figure 7. Cyclic voltammogram of 9 in CH2Cl2 (top) and in
THF (bottom); 0.1 M [nBu4N][PF6]; Au electrode; E vs Fc0/þ
scan rate = 100 mV/s; 20 °C.
;
Figure 6. Coordinate system for the interpretation of the CV
and EPR data. x and y are chosen arbitrarily.
Complexes 7-9 possess a d5 configuration. The dxy orbital
(see Figure 6 for coordinate system) is expected to be the
SOMO. As a result, facile oxidations and reductions were
anticipated. The redox properties of 9 were also probed by
CV measurements in CH2Cl2 and THF solutions (Figures 7
and Supporting Information). They show a fully reversible
reduction wave (E1/2=-1.62 V vs Fc0/þ, ic/ia=1 in THF;
E1/2=-1.62 V vs Fc0/þ, ic/ia=1.03 in CH2Cl2) and an irre-
versible oxidation process (Ep/2=-0.869 V in THF; Ep/2
=
-0.882 V in CH2Cl2) followed by a reversible oxidation (E1/2
=
0.13 V, ic/ia=0.94 in THF; E1/2=0.16 V, ic/ia=1.01 in CH2-
Cl2). The reduction wave probably belongs simply to one elec-
tron reduction of 9 to 9- anion. The irreversibility of the first
oxidation wave is not yet understood. The full irreversibility
retains up to 2 V/s, suggesting that fast transformation is cou-
pled with oxidation process. This transformation probably
does not involve exchange of ligand to solvent because of sim-
ilarity of behaviors of this wave in THF and CH2Cl2.
9 was also investigated by EPR spectroscopy (Figure 8).
No signal was observed at room temperature; however at
temperatures below 50 K a signal was detected. It is strongly
anisotropic with individual g factor components ranging from
2.6 to 1.6. The fitting of this spectrum could be carried out
approximating the structure of 9 to rhombic symmetry with
the z-axis in the direction of the acetylide ligand and the
x- and y-axes in the direction of the C2-axis between the
phosphorus atoms (Figure 6).
Figure 8. Experimental (bottom) and modeled (top) solid-state
EPR spectra of powdered 9 at 30 K.
P nuclei. The obtained values for components of the g-factor
are in the expected range for d5 low-spin systems,27 where
two main factors affect the anisotropy of g: (a) the splitting of
the T2g ground term due to the low symmetry of the coordi-
nation sphere and (b) the spin-orbital coupling leading to
mixing of these split states. The crystal field in our case is strongly
distorted from octahedral symmetry with the π-acceptor inter-
action as an important factor. Such asymmetry around a 5d
metal atom could lead to significant separation of the dxy from
dxz and dyz orbitals to give an isotropic signal at g=2. How-
ever, spin-orbital coupling, which can be strong for the heavy
metal tungsten, has an opposite influence and would increase
the g anisotropy. Particularly for d5 low-spin complexes of
group VI metals, such strong g anisotropy is not typical. The
related [trans-M(CO)2(dppm)2]þ (M=Cr, Mo; dppm=1,2-
bis(diphenylphosphinomethane)) have well-resolved EPR
The spectrum however was modeled with gx=2.57, gy=
2.24, and gz=1.61 (Figure 8). The quality of the spectrum did
not allow a reliable estimate of the hyperfine coupling of the
(26) Semenov, S. N.; Blacque, O.; Fox, T.; Venkatesan, K.; Berke, H.
J. Am. Chem. Soc. 2010, 132, 3115.
(27) Rieger, P. H. Coord. Chem. Rev. 1994, 135, 203.

6326 Organometallics, Vol. 29, No. 23, 2010
Semenov et al.
spectra, while for [trans-W(CO)2(dppm)2]þ only unclearness
of the spectrum was mentioned.28 The g tensor obtained for 9
is less anisotropic than in Ru3þ or Os3þ tris-bipyridyl com-
plexes, where strong spin-orbital coupling cannot be com-
pensated by strong distortion, and it is then closer to the
[Fe(bipy)3]3þ (bipy-2,20-bipyridyl) values.29 The EPR experi-
ment indeed confirmed the mixing of dxy with dxz and dyz
orbital characters in the [trans-W(CO)(dppe)2(CtC)] frag-
ment.15 This would also provide an explanation for the signif-
icant antiferromagnetic coupling between such centers in
related bridged W(d5)(bridge)W(d5) molecules. Electrons in
a pure dxy orbital (δ-symmetry) cannot interact with the orbitals
of the acetylide ligand, since these are of π-symmetry; how-
ever upon mixing with the dxz and dyz, the orbital symmetry
restriction is lifted, thereby providing an antiferromagnetic
long-distance through-bridge exchange in the dinuclear case.15
spectra and at 75 MHz for 13C{1H} spectra, and on Bruker-
DRX-500 and Bruker-AV2-500 spectrometers at 500 MHz for
1H, 125.8 MHz for 13C{1H}, and 202.5 MHz for 31P{1H}.
Chemical shifts for 1H and 13C are given in ppm relative to
TMS, and those for 31P relative to phosphoric acid. The UV-vis
and near-IR spectra were recorded on Varian CARY 50 Scan
UV-visible and on Varian CARY 500 Scan UV-visible/near-
IR spectrometers. CHN elemental analyses were performed
with a LECO CHN-932 microanalyzer. Cyclic voltammograms
were obtained with a BAS 100 W voltammetric analyzer
equipped with the low-volume cell. The cell was equipped with
an Au working and a Pt counter electrode and a nonaqueous
reference electrode. All sample solutions (THF or CH2Cl2) were
approximately 2 ꢀ 10-3 M in substrate and 0.1 M in Bu4NPF6
and were prepared under nitrogen. Ferrocene was subsequently
added, and the calibration of voltammograms recorded. The
BAS 100W program was employed for data analysis. X-band
EPR spectra were obtained using a Bruker EMX electron spin
resonance system (resolution 2048; central field 3400 G; sweep
width 3000 G; frequency 9.448 GHz; modulation frequency
100 kHz; modulation amplitude 10 G; time constant 20.48 ms,
conversion time 40.96 ms; receiver gain 2.24 ꢀ 104). The
spectrum was modeled using the SimFonia program (frequency
9.448 GHz; gx=2.57; gx=2.24; gx=1.61; line width x-direc-
tion 42 G; line width y-direction48 G; line widthy-direction68 G).
X-ray Diffraction Studies on 2, 3, 6, 7, 9, and 10. Intensity data
for all crystals were collected at 183(2) K on an Oxford Xcalibur
diffractometer (4-circle kappa platform, Ruby CCD detector,
Conclusion
In conclusion, we have shown that [trans-W(CO)(N2)(dp-
pe)2] is a suitable starting material for the preparation of
tungsten butatrienylidene complexes of the type [cis-W(CO)-
(dppe)2{CdCdCdC(SnMe3)(R)}]. We demonstrated that R
has a strong influence on the deprotection process and also
showed that the bistrimethyltin derivative could be readily
destannylated by NBu4F to give the corresponding buta-
diyne compound. The UV-vis data revealed that such a
difference in stability can be attributed to electronic effects,
particularly the higher HOMO/LUMO gap in the case of
aryl substitution. The reaction of the N2 complex with stanny-
lated acetylenes and subsequent removal of the SnMe3 moi-
eties by UV or thermal activation constitutes a new synthetic
access to unique [trans-W(CO)(dppe)2(CtCR)] acetylides.
The electronic structures of these complexes were studied by
CV and EPR measurements. The accessibility of the buta-
diyne derivatives and the W(I) acetylide complexes opens
up new avenues for the development of binuclear com-
plexes with longer conjugated bridges, i.e., for instance
μ-C8 compounds.
and a single-wavelength Enhance X-ray source with Mo KR
32
radiation, λ=0.71073 A) using the CrysAlisPro program.32
˚
The selected single crystals were mounted using polybutene oil
on the top of a glass fiber fixed on a goniometer head and imme-
diately transferred to the diffractometer. The crystal structures
were solved with SHELXS-9733 using direct methods. The struc-
ture refinements were performed by full-matrix least-squares on
F2 with SHELXL-97.33 The program PLATON34 was used to
check the results of the X-ray analyses. All programs used dur-
ing the crystal structure determination process are included in
the WINGX software.34 CCDC 783485-783490 contain the sup-
plementary crystallographic data (excluding structure factors)
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.
[cis-W(CO)(dppe)2{CdCdCdC(SnMe3)2}] (2). [trans-W(CO)-
(N2)(dppe)2] (100 mg, 0.096 mmol) and Me3SnCtCCtCSnMe3
(43 mg, 0.116 mmol) were placed in a Young-Schlenk tube in 10 mL
of benzene. Three freeze-pump-thaw cycles were carried out on
the resulting solution to remove any dissolved nitrogen. The reac-
tion mixture was heated under vacuum at 60 °C for 5 h. The re-
sulting dark orange solution was concentrated to 1.5 mL in vacuo
and layered with 10 mL of pentane. Complex 2 was obtained as
brown-orange prisms in 10 h. Yield: 95 mg (0.069 mmol, 72%).
Single crystals suitable for X-ray diffraction were grown by layer-
ing a benzene solution with pentane. Anal. Calcd for C63H66OP4-
Sn2W: C, 54.66; H, 4.81. Found: C, 54.92; H, 4.99. IR (cm-1): ν=
1786 (CO), 1808 (CO), 1926 (C4). 1H NMR (500 MHz, C6D6): δ
8.59 (t, JH-H=9 Hz, 2H, C6H5), 8.54 (t, JH-H=9 Hz, 2H, C6H5),
7.45 (t, JH-H = 8 Hz, 2H, C6H5), 7.35-7.25 (m, 5H, C6H5),
7.21-6.56 (m, 20H, C6H5), 6.38 (t, JH-H=8 Hz, 1H, C6H5), 6.17
(t, JH-H=8 Hz, 2H, C6H5), 3.15-2.88 (m, 2H, CH2), 2.64 - 2.05
(m, 2H, CH2), 1.85-1.72 (m, 4H, CH2), 0.31 (s, 9H, SnCH3 (d,
Experimental Section
General Procedures. All the manipulations were carried out
under a nitrogen atmosphere using Schlenk techniques or a dry-
box. Reagent grade benzene, toluene, hexane, pentane, diethyl
ether, and tetrahydrofuran were dried and distilled from sodium
benzophenone ketyl prior to use. Dichloromethane and acetoni-
trile were distilled from CaH2. The literature procedures were used
to prepare the following compounds: Me3SnCtCCtCSiMe3,30
[trans-W(CO)(N2)(dppe)2],20 and [cis-W(CO)(dppe)2{CdCdCdC-
(SnMe3)(p-C6H4tBu)}].15 Me3SnCtCCtCSnMe3 was prepared
by a modified literature protocol (see Supporting Information).31
All other chemicals were used as obtained from commercial
suppliers. The IR spectra were obtained on a Bio-Rad FTS-45
instrument and a Bio-Rad Excalibur FTS-3500 instrument. NMR
spectra were measured on a Varian Mercury spectrometer at
200 MHz for the 1H nucleus and at 81 MHz for 31P{1H} spectra,
on a Varian Gemini-2000 spectrometer at 300 MHz for 1H
2
satellite, JH-Sn =52 Hz)). 119Sn NMR (184.6 MHz, C6D6): δ
-22.5 (m, SnMe3). 31PNMR(81MHz, C6D6): δ48.8 (m, 1P), 44.9
(m, 1P), 30.0 (m, 1P), 26.8 (m, 1P). 13C NMR (125 MHz, C6D6):
249.5 (q, 2JC-P=11 Hz, CR), 222.8 (d, 2JC-P=28 Hz, CO), 144.1
(28) Bond, A. M.; Colton, R.; Jackowski, J. J. Inorg. Chem. 1975, 14,
2526.
(29) DeSimone, R. E.; Drago, R. S. J. Am. Chem. Soc. 1970, 92, 2343.
(30) Zheng, Q. L.; Hampel, F.; Gladysz, J. A. Organometallics 2004,
23, 5896.
(31) Brefort, J. L.; Corriu, R. J. P.; Gerbier, P.; Guerin, C.; Henner,
B. J. L.; Jean, A.; Kuhlmann, T.; Garnier, F.; Yassar, A. Organome-
tallics 1992, 11, 2500.
(32) Xcalibur CCD System; Oxford Diffraction Ltd: Abingdon, Oxfordshire,
England, 2007.
(33) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112.
(34) Spek, A. L. J. Appl. Crystallogr. 2003, 36, 7.

Article
Organometallics, Vol. 29, No. 23, 2010 6327
1
(d, JC-P = 28 Hz, ipso-C6H5), 142.3 (d, JC-P = 29 Hz, ipso-
1
(d, JC-P=11 Hz, C6H5), 133.8 (d, JC-P=11 Hz, C6H5), 133.5
(d, JC-P=11 Hz, C6H5), 133.3 (d, JC-P=11 Hz, C6H5), 132.8 (d,
JC-P=11 Hz, C6H5), 131.3 (d, JC-P=11 Hz, C6H5), 131.5 (d,
1
1
C6H5), 140.7 (d, JC-P =25 Hz, ipso-C6H5), 139.9 (d, JC-P
=
46 Hz, ipso-C6H5), 139.4 (d, 1JC-P=45 Hz, ipso-C6H5), 137.9 (d,
1JC-P=25 Hz, ipso-C6H5), 136.4 (d, 1JC-P=28 Hz, ipso-C6H5),
134.6 (d, JC-P=11 Hz, C6H5), 133.4 (d, JC-P=10 Hz, C6H5), 133.1
(m, C6H5), 132.6 (s, C6H5), 132.5 (s, C6H5), 132.4 (s, C6H5), 132.3
(s, C6H5), 131.7 (d, JC-P=11 Hz, C6H5), 131.3 (dd, JC-P=10 Hz,
J
(s, C6H5), 128.8 (s, C6H5), 128.6 (s, C6H5), 128.5 (s, C6H5), 127.3
C-P = 11 Hz, C6H5), 131.0 (d, JC-P = 11 Hz, C6H5), 129.1
3
(s, C6H5), 127.2 (s, C6H5), 127.1 (s, C6H5), 90.8 (d, JC-P
=
15 Hz, Cβ), 32.8 (dd, 1JC-P=24 Hz, 2JC-P=16 Hz, CH2), 29.7
(m, CH2), 28.1 (dd, 1JC-P=22 Hz, 2JC-P=12 Hz, CH2), -3.2
(s, SnCH3 (d, satellite 1JC-Sn=313 Hz)).
JC-P=3 Hz, C6H5), 129.1 (dd, JC-P=18 Hz, JC-P=2 Hz, C6H5),
128.5 (s, C6H5), 128.4 (s, C6H5), 128.3 (s, C6H5), 124.8 (s, Cβ),
1
124.7 (s, Cγ), 46.8 (s, (d, satellite, JC-Sn = 303 Hz) Cδ), 32.5
(m, CH2), 30.2 (dd, JC-P =23 Hz, JC-P =13 Hz, CH2), 28.5
[cis-W(CO)(dppe)2{CdC(SnMe3)(Ph)}] (5). An analogous pro-
cedure to 2 was followed applying [trans-W(CO)(N2)(dppe)2]
(20 mg, 0.0193 mmol) and PhCtCSnMe3 (5.6 mg, 0.021 mmol).
Yield: 16 mg (0.0125 mmol, 65%). Anal. Calcd for C64H63OP4-
SnW: C, 60.31; H, 4.98. Found: C, 60.55; H, 5.07. IR (cm-1): ν=
1783 (CO). 1H NMR (500 MHz, THF-d8): δ 8.17 (t, JH-H=8 Hz,
2H, C6H5), 7.74 (m, 6H, C6H5), 7.25-7.00 (m, 25H, C6H5), 6.89
(q, J=8 Hz, 4H, C6H5), 6.78 (t, J=7 Hz, 2H, C6H5), 6.68 (t, J=
7 Hz, 2H, C6H5), 6.56 (t, J=7 Hz, 1H, C6H5), 6.23 (t, J=7 Hz, 2H,
C6H5), 6.17 (t, J=7 Hz, 2H, C6H5), 3.18 (m, 1H, CH2), 3.18 (m,
1H, CH2), 2.22-1.62 (m, 6H, CH2), -0.46 (s, 9H, SnCH3
1
2
1
2
(dd, JC-P=23 Hz, JC-P=15 Hz, CH2), -7.0 (s, (d, satellite,
1JC-Sn=324 Hz), CH3).
[cis-W(CO)(dppe)2{CdCdCdC(SnMe3)(SiMe3)}] (3). An anal-
ogous procedure to 2 was followed applying [trans-W(CO)(N2)-
(dppe)2] (100 mg, 0.096 mmol) and Me3SnCtCCtCSiMe3 (33 mg,
0.116 mmol). Yield: 80 mg (0.062 mmol, 65%). Single crystals suit-
able for X-ray diffraction were grown by layering a toluene solution
with pentane. Anal. Calcd for C63H66OP4SnSiW: C, 58.49; H, 5.14.
Found: C, 58.62; H, 5.09. IR (cm-1): ν=1798 (CO), 1935 (C4). 1H
NMR (500 MHz, C6D6): δ 8.48 (t, JH-H=9 Hz, 2H, C6H5), 8.43
(t, JH-H=9 Hz, 2H, C6H5), 7.60 (t, JH-H=8 Hz, 2H, C6H5), 7.35
(t, JH-H =8 Hz, 2H, C6H5), 7.21 (q, JH-H=8 Hz, 2H, C6H5),
7.14-7.09 (m, 10H, C6H5), 7.03-6.68 (m, 12H, C6H5), 6.62 (t,
JH-H=8 Hz, 4H, C6H5), 6.53 (t, JH-H=7 Hz, 2H, C6H5), 6.49
(t, JH-H = 8 Hz, 2H, C6H5), 6.06 (t, JH-H =8 Hz, 2H, C6H5),
3.05-2.80 (m, 2H, CH2), 2.56-2.25 (m, 2H, CH2), 2.19-1.97 (m,
3H, CH2), 1.73-1.62 (m, 1H, CH2), 0.28 (s, 9H, SiCH3), 0.25 (s, (d,
satellite, 2JH-Sn=52 Hz), 9H, SnCH3). 119Sn NMR (184.6 MHz,
C6D6): δ -26.1 (m, SnMe3). 31P NMR (81 MHz, C6D6): δ 48.7 (m,
1P), 44.3 (m, 1P), 29.5 (m, 1P), 26.2 (m, 1P). 13C (125 MHz, C6D6):
254.1 (q, 2JC-P=12 Hz, CR), 222.5 (d, 2JC-P=32 Hz, CO), 143.9
(d, 1JC-P=28 Hz, ipso-C6H5), 142.4 (s, Cβ), 142.5 (s, Cγ), 142.1
(d, 1JC-P=30 Hz, ipso-C6H5), 140.4 (d, 1JC-P=27 Hz, ipso-C6H5),
139.8 (d, 1JC-P=46 Hz, ipso-C6H5), 139.2 (d, 1JC-P=46 Hz, ipso-
C6H5), 137.9 (dd, 1JC-P=27 Hz, JC-P=6 Hz, ipso-C6H5), 137.2
2
(d, satellite, JH-Sn =50 Hz)). 119Sn NMR (184.6 MHz, THF-
d8): δ -41.4 (m, SnMe3). 31P NMR (202 MHz, C6D6): δ 40.4
(m, 1P), 38.0 (m, 1P), 24.1 (m, 1P), 21.8 (m, 1P). 13C NMR (125
MHz, THF-d8): 309.1 (dq, 2JC-P(trans)=20 Hz, 2JC-P(cis)=10 Hz,
2
CR), 225.3 (d, JC-P =28 Hz, CO), 151.7 (s, ipso-C6H5), 142.2
(d, JC-P = 32 Hz, ipso-C6H5), 140.4 (d, JC-P = 35 Hz, ipso-
1
1
C6H5), 139.1 (d, 1JC-P=33 Hz, ipso-C6H5), 138.6 (s, C6H5), 138.4
(d, JC-P = 33 Hz, ipso-C6H5), 137.9 (d, JC-P = 26 Hz, ipso-
1
1
C6H5), 136.0 (s, C6H5), 135.9 - 135.7 (m, C6H5), 132.1 (d, JC-P
=
=
11 Hz, C6H5), 131.5 (d, JC-P=11 Hz, C6H5), 131.3 (d, JC-P
11 Hz, C6H5), 131.0 (d, JC-P=11 Hz, C6H5), 130.5 (d, JC-P=11
Hz, C6H5), 129.6 (d, JC-P=11 Hz, C6H5), 129.4 (d, JC-P=11 Hz,
C6H5), 129.3 (d, JC-P = 11 Hz, C6H5), 127.2 (s, C6H5), 126.7
(s, C6H5), 126.4 (s, C6H5), 126.3 (s, C6H5), 126.0 (s, C6H5), 125.9
(s, C6H5), 125.8 (s, C6H5), 125.6 (s, C6H5), 125.5 (s, C6H5), 125.4
(s, C6H5), 125.3 (s, C6H5), 111.6 (d, 3JC-P=14 Hz, Cβ), 29.8 (dd,
(dd, 1JC-P=27 Hz, JC-P=3 Hz, ipso-C6H5), 136.0 (dd, 1JC-P
=
2
1JC-P=23 Hz, JC-P=15 Hz, CH2), 27.3 (m, CH2), 25.6 (dd,
1JC-P=25 Hz, 2JC-P=12 Hz, CH2), -8.0 (s, SnCH3 (d, satellite
25 Hz, JC-P=3 Hz, ipso-C6H5), 134.7 (d, JC-P=11 Hz, C6H5),
133.4 (d, JC-P=10 Hz, C6H5), 132.5 (d, JC-P=9 Hz, C6H5), 132.5
(d, JC-P =11 Hz, C6H5), 132.4 (d, JC-P =12 Hz, C6H5), 131.8
(d, JC-P=11 Hz, C6H5), 131.4 (dd, JC-P=10 Hz, JC-P=4 Hz,
C6H5), 129.3 (dd, JC-P = 20 Hz, JC-P = 2 Hz, C6H5), 128.7
(s, C6H5), 128.6 (s, C6H5), 128.4 (s, C6H5), 49.1 (s, (d, satellite,
1JC-Sn=310 Hz)).
[trans-W(CO)(dppe)2(CtCPh)] (7). A solution of 5 (16 mg,
0.0125 mmol) in 0.5 mL of benzene was irradiated with an UV
lamp for 5 min. The completeness of the reaction was assured by
disappearance of the 31P NMR signals of 5. The resulting solution
was concentrated to 0.3 mL and was layered with pentane to give
crystals of 6. Yield: 16 mg (0.0125 mmol, 65%). Anal. Calcd for
C61H54OP4W: C, 65.96; H, 4.90. Found: C, 66.02; H, 5.01. IR
(cm-1): ν=1793 (CO). 1H NMR (200 MHz, THF-d8): δ 17.3 (br),
13.3 (br), 8.1 (br), 7.1 (br), 6.0 (br), 5.6 (br), 5.4 (br), 0.0 (br).
[trans-W(CO)(dppe)2(CtCSnMe3)] (8). An analogous proce-
dure to that for 7 was followed using [trans-W(CO)(N2)(dppe)2]
(50 mg, 0.048 mmol) and Me3SnCtCSnMe3 (18.5 mg, 0.053 mmol).
Yield: 30 mg (0.0251 mmol, 52%). Anal. Calcd for C58H58OP4-
SnW: C, 58.17; H, 4.88. Found: C, 58.49; H, 4.86. IR (cm-1): ν=
1756 (CO). 1H NMR (200 MHz, THF-d8): δ 13.8 (br), 8.2 (br),
7.0 (br), 6.1 (br), 5.7 (br), 5.2 (br), -1.3 (br).
1
1JC-Sn =290 Hz), Cδ), 32.3 (m, CH2), 30.4 (dd, JC-P=24 Hz,
2JC-P=12 Hz, CH2), 28.3 (dd, 1JC-P=23 Hz, 2JC-P=16 Hz, CH2),
2.0 (s, SiCH3), -7.0 (s, (d, satellite, 1JC-Sn=310 Hz), SnCH3).
[cis-W(CO)(dppe)2{CdC(SnMe3)2}] (6). An analogous pro-
cedure to 2 was applied starting from [trans-W(CO)(N2)(dppe)2]
(20 mg, 0.0193 mmol) and Me3SnCtCSnMe3 (7.4 mg, 0.021
mmol). A higher concentration of 4 and cooling were required to
initialize crystallization of 4. Yield: 8 mg (0.0059 mmol, 30%).
Single crystals suitable for X-ray diffraction were grown by layer-
ing a benzene solution with pentane. Anal. Calcd for C61H67OP4-
Sn2W: C, 53.82; H, 4.96. Found: C, 54.02; H, 4.09. IR (cm-1):
ν=1789 (CO). 1H NMR (500 MHz, C6D6): δ 8.48 (t, J=8 Hz,
2H, C6H5), 8.42 (t, J=8 Hz, 2H, C6H5), 8.16 (t, J=8 Hz, 2H,
C6H5), 8.00 (t, J=9 Hz, 2H, C6H5), 7.84 (t, J=7 Hz, 2H, C6H5),
7.60 (t, J=8 Hz, 2H, C6H5), 7.42 (t, J=7 Hz, 2H, C6H5), 7.36
(t, J=8 Hz, 4H, C6H5), 7.16 (m, 8H, C6H5), 7.00 (m, 8H, C6H5),
6.81 (t, J=7 Hz, 2H, C6H5), 6.75 (t, J=7 Hz, 2H, C6H5), 6.23 (m,
4H, C6H5), 2.65 (m, 2H, CH2), 2.29-1.60 (m, 6H, CH2), 0.28 (s,
18H, SnCH3 (d, satellite, 2JH-Sn=52 Hz)). 119Sn NMR (184.6
MHz, C6D6): δ -32.2 (m, SnMe3). 31P NMR (202 MHz, C6D6):
δ 42.5 (m, 1P), 38.3 (m, 1P), 28.7 (m, 1P), 26.7 (m, 1P). 13C NMR
(125 MHz, C6D6): 297.6 (s, CR), 226.2 (d, 2JC-P=23 Hz, CO),
[trans-W(CO)(dppe)2(CtCSiMe3)] (9). [trans-W(CO)(N2)-
(dppe)2] (100 mg, 0.096 mmol) and Me3SnCtCSiMe3 (30 mg,
0.116 mmol) were placed in a Young-Schlenk tube in 6 mL of
benzene. Three freeze-pump-thaw cycles was carried out to
remove any dissolved nitrogen. The reaction mixture was heat-
ed under vacuum to 65 °C for 6 h. The freeze-pump-thaw cycles
were repeated twice during the reaction. The resulting yellow
solution was irradiated with an UV lamp for 5 min until the 31
P
NMR signals of the vinylidene derivative disappeared. How-
ever, the vinylidene complex turned out to be unstable in this
case, and irradiation was not required if the reaction was car-
ried out overnight. Then the reaction mixture was concentrated
to 1.5 mL in vacuo and layered with 10 mL of pentane. 7 crys-
tallized as red prisms in 10 h. Yield: 50 mg (0.0452 mmol, 47%).
Anal. Calcd for C58H58OP4SiW: C, 62.93; H, 5.28. Found: C,
1
1
144.9 (d, JC-P=34 Hz, ipso-C6H5), 142.6 (d, JC-P=27 Hz,
1
ipso-C6H5), 141.8 (d, JC-P = 27 Hz, ipso-C6H5), 141.5 (d,
1JC-P = 34 Hz, ipso-C6H5), 141.2 (d, JC-P = 27 Hz, ipso-
C6H5), 140.4 (d, JC-P=22 Hz, ipso-C6H5), 140.1 (d, JC-P=
1
1
1
18 Hz, ipso-C6H5), 138.7 (d, 1JC-P=34 Hz, ipso-C6H5), 134.0

6328 Organometallics, Vol. 29, No. 23, 2010
Semenov et al.
62.80; H, 5.13. IR (cm-1): ν=1756 (CO). 1H NMR (200 MHz,
THF-d8): δ 14.1 (br), 8.2 (br), 7.0 (br), 5.8 (br), 5.5 (br), 5.1 (br),
3.1 (br), 0.2 (br).
NCH2), 2.38 (m, 4H, CH2), 2.19 (m, 4H, CH2), 1.63 (pent,
J
H-H=8 Hz, 8H, NCH2CH2), 1.36 (hex, JH-H=7.5 Hz, 8H,
NCH2CH2CH2), 1.25 (s, 1H, CH), 1.01 (s, JH-H=7 Hz, 12H
NCH2CH2CH2CH2). 31P NMR (81 MHz, C6D6): δ 45 br. 13
[trans-W(CO)(dppe)2(CtCCtCH)][NBu4] (10). A solution
of 2 (20 mg, 0.01445 mmol) in 0.5 mL of THF-d8 was mixed
with a solution of NBu4F 3H2O (11 mg, 0.035 mmol) in 0.5 mL of
C
NMR (125 MHz, CD2Cl2): δ 213.1 (m, CR), 141.7 (br, C6H5-
ipso), 139.9 (br, C6H5-ipso), 135.5 (s, C6H5), 134.0 (s, C6H5),
129.4 (s, C6H5), 126.8 (s, C6H5), 86.5 (s, Cβ) 36.0 (m, CH2).
3
THF-d8 in a Young-Schlenk tube at -50 °C. Then the reaction
mixture was transferred to a precooled NMR spectrometer.
The temperature was raised to room temperature in approxi-
mately 1 h. The resulting mixture was kept at room tempera-
ture for one more hour and evaporated in vacuo. The residue
was then washed with toluene three times to give 10. Yield:
8 mg (0.0061 mmol, 42%). (A satisfactory elemental analysis
could not be obtained due to thermal instability of this com-
plex.) IR (cm-1): ν=3300 (tCH), 2056 (CtC), 1709 (CO). 1H
NMR (500 MHz, THF-d8): δ 7.41 (br, 8H, C6H5), 7.26 (br, 8H,
C6H5), 6.93-6.88 (m, 24H, C6H5), 3.21 (t, JH-H=8.5 Hz, 8H,
Acknowledgment. Funding from the Swiss National
Science Foundation (SNSF) and from the University of
€
Zurich are gratefully acknowledged.
Supporting Information Available: Details of preparation of
Me3SnCtCCtCSnMe3, CV studies of 2 and 4, thermal ellip-
soid plot for 7. This material is available free of charge via the
Internet at http://pubs.acs.org.