Hydrogen atom transfer reactions of the unsaturated hydroxycarbyne complex [W2Cp2(μ-COH)(μ-PPh2)2]BF 4

Article abstract of DOI:10.1021/om400598m

The hydroxycarbyne complex salt [W₂Cp₂(μ-COH) (μ-PPh₂)₂]BF₄ (1) reacted rapidly with water in the presence of the oxidant [FeCp₂]BF₄ to give the hydroxo complex salt [W₂Cp₂(OH)(μ-PPh₂) ₂(CO)]BF₄, a preparation that could be replicated using the neutral carbonyl complex [W₂Cp₂(μ-PPh ₂)₂(μ-CO)] (2) instead. A similar reaction took place slowly with HSPh and rapidly in the presence of [FeCp₂]BF ₄, to yield the known 32-electron complex salt [W₂Cp ₂(SPh)(μ-PPh₂)₂(CO)]BF₄. In contrast, 1 did not react with PhOH or H₂Np-tol even in the presence of [FeCp₂]BF₄. However, a fast reaction between these molecules and 2 took place in the presence of [FeCp₂]BF₄, to give the phenolato complex salt [W₂Cp₂(OPh)(μ- PPh₂)₂(CO)]BF₄ and the imido-hydride [W ₂Cp₂(μ-H)(Np-tol)(μ-PPh₂) ₂(CO)]BF₄ (W-W = 2.9135(8) A), respectively, after formal elimination of hydrogen. The hydroxycarbyne complex 1 reacted rapidly with PH₂Cy to give the hydride derivative [W₂Cp ₂(H)(μ-PPh₂)₂(CO)(PH₂Cy)]BF ₄, this requiring H-migration from O to W atoms. The M-H bonds in the latter hydride cations were deprotonated by strong bases to give the corresponding neutral complexes [W₂Cp₂(Np-tol)(μ- PPh₂)₂(CO)] and [W₂Cp₂(μ-PPh ₂)₂(CO)(PH₂Cy)]. Compound 1 also reacted easily with two-electron donors such as NCMe, CN^tBu, and CNp-tol, to give products derived from the addition of two molecules of reagent in each case, and some rearrangement of the COH ligand. The first reaction gave the new cationic complex [W₂Cp₂(μ-PPh₂)₂(μ-N:N, N′-N₂HC₂Me₂)(CO)]BF₄, derived from the C-C coupling of two nitrile molecules accompanied by an O to N shift of the hydroxycarbyne proton. In contrast, no C-C coupling processes were observed in the reactions with isocyanides, although proton migration occurred in all cases, either to the metal (reaction with CN^tBu), to give the hydride [W₂Cp₂(H)(μ-PPh₂)₂(μ-CN ^tBu)(CN^tBu)]BF₄, or to the N atom of one of the incoming isocyanides (reaction with CNp-tol), to give the aminocarbyne derivative [W₂Cp₂{μ-CN(H)p-tol}(μ-PPh ₂)₂(CNp-tol)(CO)]BF₄.

Full text of DOI:10.1021/om400598m

Article
pubs.acs.org/Organometallics
Hydrogen Atom Transfer Reactions of the Unsaturated
Hydroxycarbyne Complex [W2Cp2(μ-COH)(μ-PPh2)2]BF4
Fernanda Cimadevilla,† M. Esther García,† Daniel García-Vivo,† Miguel A. Ruiz,*,† Claudia Graiff,‡
́
and Antonio Tiripicchio‡
†Departamento de Química Organ
́
ica e Inorgan
́
ica/IUQOEM, Universidad de Oviedo, E-33071 Oviedo, Spain
‡Dipartimento di Chimica, Universita
̀
di Parma, Viale delle Scienze 17/A, I-43100 Parma, Italy
S
* Supporting Information
ABSTRACT: The hydroxycarbyne complex salt [W2Cp2(μ-
COH)(μ-PPh2)2]BF4 (1) reacted rapidly with water in the
presence of the oxidant [FeCp2]BF4 to give the hydroxo
complex salt [W2Cp2(OH)(μ-PPh2)2(CO)]BF4, a preparation
that could be replicated using the neutral carbonyl complex
[W2Cp2(μ-PPh2)2(μ-CO)] (2) instead. A similar reaction took
place slowly with HSPh and rapidly in the presence of
[FeCp2]BF4, to yield the known 32-electron complex salt
[W2Cp2(SPh)(μ-PPh2)2(CO)]BF4. In contrast, 1 did not react
with PhOH or H2Np-tol even in the presence of [FeCp2]BF4.
However, a fast reaction between these molecules and 2 took place in the presence of [FeCp2]BF4, to give the phenolato
complex salt [W2Cp2(OPh)(μ-PPh2)2(CO)]BF4 and the imido-hydride [W2Cp2(μ-H)(Np-tol)(μ-PPh2)2(CO)]BF4 (W−W =
2.9135(8) Å), respectively, after formal elimination of hydrogen. The hydroxycarbyne complex 1 reacted rapidly with PH2Cy to
give the hydride derivative [W2Cp2(H)(μ-PPh2)2(CO)(PH2Cy)]BF4, this requiring H-migration from O to W atoms. The M−H
bonds in the latter hydride cations were deprotonated by strong bases to give the corresponding neutral complexes [W2Cp2(Np-
tol)(μ-PPh2)2(CO)] and [W2Cp2(μ-PPh2)2(CO)(PH2Cy)]. Compound 1 also reacted easily with two-electron donors such as
NCMe, CNtBu, and CNp-tol, to give products derived from the addition of two molecules of reagent in each case, and some
rearrangement of the COH ligand. The first reaction gave the new cationic complex [W2Cp2(μ-PPh2)2(μ-N:N,N′-
N2HC2Me2)(CO)]BF4, derived from the C−C coupling of two nitrile molecules accompanied by an O to N shift of the
hydroxycarbyne proton. In contrast, no C−C coupling processes were observed in the reactions with isocyanides, although
proton migration occurred in all cases, either to the metal (reaction with CNtBu), to give the hydride [W2Cp2(H)(μ-PPh2)2(μ-
CNtBu)(CNtBu)]BF4, or to the N atom of one of the incoming isocyanides (reaction with CNp-tol), to give the aminocarbyne
derivative [W2Cp2{μ-CN(H)p-tol}(μ-PPh2)2(CNp-tol)(CO)]BF4.
The above studies were followed by a systematic study on
the synthesis and reactivity of related methoxycarbyne-bridged
species. We could thus easily prepare the 30-electron complexes
[W2Cp2(μ-COMe)(μ-PPh2)2]CF3SO3,1 [M2Cp2(μ-COMe)(μ-
INTRODUCTION
■
Some time ago we reported the preparation of the cationic
hydroxycarbyne complex salt [W2Cp2(μ-COH)(μ-PPh2)2]BF4
(1), a species selectively formed via O-protonation of the
bridging carbonyl in the neutral complex [W2Cp2(μ-PPh2)2(μ-
CO)] (2) (Scheme 1).1 At that time, 1 was the first reported
complex having a hydroxycarbyne ligand bridging a triple
metal−metal bond and the second hydroxycarbyne complex
with enough thermal stability so as to be handled at room
temperature.2 Not unexpectedly, the combined presence of
multiple M−M and M−C bonds in this cation makes it quite
reactive; actually, this species was found to be quite air-
sensitive, transforming progressively into the hydroxo carbonyl
derivative [W2Cp2(OH)(μ-PPh2)2(CO)]BF4 (3), which in turn
underwent an unusual intramolecular oxidative addition of the
O−H bond at room temperature, to give the oxohydride
isomer [W2Cp2(μ-H)(O)(μ-PPh2)2(CO)]BF4 (4) (Scheme
1).1 The formation of 3 apparently followed from the reaction
of 1 with oxygen, but no proof of it was obtained at the time.
PCy2)(μ-CO)] (M = Mo,3a,b W),3c [Mo2Cp2(μ-COMe)2(μ-
4a
PCy2)]BF4,4 [Mo2Cp2(μ-COMe)(μ-PEt2)2]BF4
and
5
[Mo2Cp2(μ-COMe)(μ-CPh)(μ-PCy2)]CF3SO3 by O-methyl-
ation of suitable carbonyl-bridged precursors. These methox-
ycarbyne complexes were found to be more robust than their
hydroxycarbyne analogues but still retained a high reactivity
derived from the unusual combination of multiple M−M and
M−C bonds. The reactivity of the cationic complexes was
dominated by the electrophilic nature of the unsaturated
dimetal center.1,2,4b,5,6 In contrast, the neutral complex
[Mo2Cp2(μ-COMe)(μ-PCy2)(μ-CO)] had a biphilic behavior,
actually displaying a remarkable multisite reactivity involving
not only the multiple Mo−Mo and Mo−C bonds but also the
Received: June 21, 2013
© XXXX American Chemical Society
A
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Scheme 1
RESULTS AND DISCUSSION
Revisiting the Transformation of Compound 1 into 3.
■
As noted above, compound 1 progressively transforms into the
oxohydride 4 via the thermally unstable hydroxo isomer 3, in a
reaction usually requiring a few days for completion in solution
(Scheme 1). In our preliminary communication we attributed
such transformation to a slow reaction with adventitious
oxygen. However, we have now identified water as the actual
source of oxygen in this reaction. First, a separate experiment
revealed that bubbling dry air through a dichloromethane
solution of compound 1 at temperatures in the range 253−273
K (conditions in which the transformation 3 → 4 is very slow)
did not speed up the formation of 3 to a significant extent.
Second, separate experiments revealed that compound 1 also
failed to react with other potential sources of oxygen, such as
olefin oxides. In contrast, the transformation of 1 into the
oxohydride 4 could be completed within a few hours upon
addition of water at room temperature to dichloromethane
solutions of 1, in a reaction occurring via the hydroxo isomer 3,
as revealed by IR and 31P{1H} NMR monitoring. Finally and
interestingly, the reaction of 1 with water turned out to be
instantaneous in the presence of stoichiometric amounts of the
oxidant [FeCp2]BF4, to give 3 (Scheme 2). In the latter case,
essentially single C−O and O−Me bonds of the methox-
ycarbyne ligand.7 In the course of all these studies we also
prepared some dimolybdenum hydroxycarbyne complex salts
related to the ditungsten complex 1, such as [Mo2Cp2(μ-
COH)(μ-PCy2)2]BF4,8 [Mo2Cp2(μ-COH)(μ-PEt2)2]BF4,4a
and [Mo2Cp2(μ-COH)(μ-COMe)(μ-PCy2)]BF4.4a However,
only the former proved to be stable enough at room
temperature (although decomposing in solution slowly),
while the latter two compounds evolved at room temperature
to give hydride-carbonyl isomers, which in turn were also
unstable species decomposing progressively upon manipulation.
In summary, the chemical behavior of hydroxycarbyne
complexes remains largely unexplored to date. Yet, any study
of the reactivity of the hydroxycarbyne ligand at an unsaturated
dimetal center might be of interest not only because of the
unusual transformations that can be induced by the coexistence
of different multiple bonds (M−M and M−C) in the same
substrate, but also in the context of the metal-catalyzed
hydrogenation processes of carbon monoxide.9 In fact, we have
observed some relevant transformations related to the Fischer−
Tropsch synthesis in our previous work on the 32-electron
hydroxycarbyne complex [W2Cp2(μ-COH)(μ-Ph2PCH2PPh2)-
(CO)2]+, including an unusual reduction to CH,2c and the
insertion of CH2 into the O−H bond or its coupling with the
carbyne ligand.2a It was thus of interest to examine the chemical
behavior of even more unsaturated hydroxycarbyne complexes
such as the 30-electron cation of compound 1, which is the
purpose of the present paper. We have now revisited its unusual
transformation into the hydroxo species 3 and analyzed its
reactivity toward simple donors such as isocyanides and nitriles
and donors having potentially reactive E−H bonds (E = O, S,
N, P). We have found that the latter reactions can be greatly
accelerated in the presence of the oxidant [FeCp2]BF4, in a
process that can be essentially replicated using the neutral
complex 2 and involves the highly reactive radical cation
[W2Cp2(μ-PPh2)2(μ-CO)]+. We note that we have recently
used a similar strategy to increase the reactivity of the
isoelectronic and isostructural benzylidyne complex
[Mo2Cp2(μ-CPh)(μ-PCy2)(μ-CO)].10 As it will be shown
below, all reactions of 1 involve the cleavage of the O−H bond
of the hydroxycarbyne ligand by following at least four different
pathways: (a) dehydrogenation in the reactions with E−H
molecules, (b) deprotonation following oxidation, (c) H-
transfer to the metal center, to give hydride derivatives, and (d)
H-transfer to the incoming ligand.
Scheme 2
the formation of 3 must be preceded by an oxidized form of the
hydroxycarbyne complex, possibly the (undetected) radical
dication [W2Cp2(μ-COH)(μ-PPh2)2]2+ (1+), which would
react with a water molecule with overall abstraction of an
oxygen atom and release of a proton and an H atom (likely as
H2). Then, we reasoned that 1-electron oxidation in the neutral
compound 2 would generate a related radical [W2Cp2(μ-
CO)(μ-PPh2)2]+ (2+), possibly reacting rapidly with water to
give 3, in a reaction paralleling the recently reported redox-
induced reactions of the benzylidyne complex [Mo2Cp2(μ-
CPh)(μ-PCy2)(μ-CO)].10 Indeed we found that 2 is rapidly
transformed into 3 upon addition of water and [FeCp2]BF4 to
dichloromethane solutions of the complex (Scheme 2). The
mechanistic aspects of the above transformations will be
discussed later on.
Reactions of Compound 1 with HERn Molecules. We
have examined the reactions of 1 with simple donors having E−
H bonds common in many biologically relevant molecules (O−
H, S−H, and N−H) and a few other ones. However, we have
found that these reactions are severely limited by the kinetics,
for if the reaction of 1 with the incoming molecule is slow, then
reaction with adventitious water occurs preferentially to
eventually give the oxohydride 4. As it will be discussed
B
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
below, the redox-induced reactions of 1 or 2 can be used as an
alternative strategy, but neither are of general applicability.
Compound 1 does not react at room temperature with
phenol even when a large excess of reagent is used: only a slow
transformation into the oxohydride 4 was observed, resulting
from the reaction with adventitious water, and the same results
(but much faster) were obtained in the presence of [FeCp2]-
BF4. In contrast, the reaction of 2 with phenol in the presence
of the latter oxidant rapidly gave the new phenolato complex
salt [W2Cp2(OPh)(μ-PPh2)2(CO)]BF4 (5) (Chart 1), along
reaction was observed with secondary phosphines, a slow
reaction took place with cyclohexylphosphine at room
temperature to give the hydride derivative [W2Cp2(H)(μ-
PPh2)2(CO)(PH2Cy)]BF4 (9), which displays a coordinated
molecule of phosphine (Chart 1). As with the case of 7, the
hydride ligand in 9 can be easily removed through
deprotonation with DBU, to give the neutral phosphine
complex [W2Cp2(μ-PPh2)2(CO)(PH2Cy)] (10) in high yield
(Chart 1).
Structural Characterization of Compound 5. The
spectroscopic data available for the phenolato complex 5 are
similar to those of the related hydroxo (3) and thiolato (6)
complexes (Table 1). Therefore, a similar structure is to be
Chart 1
Table 1. Selected IR and 31P{1H} NMR Data for New
Compounds
a
b
c
compound
ν(CO)
δP (JPP
)
JPW
364
[W2Cp2(μ-COH)(μ-PPh2)2]
186.8
d
BF4 (1)
[W2Cp2(OPh)(μ-PPh2)2(CO)] 1914 (s)
BF4 (5)
117.7
111.7
40.8
381, 272
370, 266
267, 248
385, 304
[W2Cp2(SPh)(μ-PPh2)2(CO)] 1926 (s)
e
BF4 (6)
[W2Cp2(μ-H)(Np-tol)(μ-
PPh2)2(CO)]BF4 (7)
1959 (s)
1833 (s)
1895 (s)
[W2Cp2(Np-tol)(μ-
PPh2)2(CO)] (8)
109.2
[W2Cp2(H)(μ-PPh2)2(CO)
(PH2Cy)]BF4 (9)
115.2
278, 188
367, 206
207
100.6 (20)
−25.5 (20)
81.7
[W2Cp2(μ-PPh2)2(CO)
(PH2Cy)] (10)
1855 (s)
1912 (s)
334, 334
395
with small amounts of 4 as a side product. Compound 5 is
structurally related to the hydroxo complex 3 and also is rather
unstable, experiencing progressive hydrolysis upon manipu-
lation, to eventually yield the oxohydride 4.
−14.9
−25.1
[W2Cp2(μ-PPh2)2(μ-N:N,N′-
N2HC2Me2)(CO)]BF4 (11)
251, 235
f
[W2Cp2(H)(μ-PPh2)2(μ-
CNtBu)(CNtBu)]BF4 (12)
2140 (vs),
1950 (s)
60.5
319, 245
f
Compound 1 reacts slowly with benzenethiol at room
temperature, to give the thiolato complex salt [W2Cp2(SPh)(μ-
PPh2)2(CO)]BF4 (6) (Chart 1), a compound prepared
previously in our laboratory from the reaction of 3 with the
same reagent.11 Under these conditions, the oxohydride 4 is
also formed in variable amounts due to the unavoidable
presence of trace amounts of water. Fortunately, this undesired
side reaction could be almost completely suppressed in the
presence of [FeCp2]BF4, which dramatically increased the rate
of reaction of 1 with PhSH. Not surprisingly, compound 6
could be also obtained by reacting 2 with stoichiometric
amounts of HSPh in the presence of [FeCp2]BF4, in a process
that is both faster and more selective than the one starting from
1.
f
g
g
[W2Cp2{μ-CN(H)p-tol}(μ-
PPh2)2(CNp-tol)(CO)]BF4
(13)
2108 (vs),
1960 (s)
−24.3
−26.2
229, 224
229, 222
h
h
a
Recorded in CH2Cl2 solution unless otherwise stated, with C−O
b
stretching frequencies in cm−1. Recorded at room temperature in
CD2Cl2 solutions unless otherwise stated; δ in ppm relative to external
85% aqueous H3PO4, with coupling to phosphorus indicated in
c
brackets (JPP in Hz). One-bond 31P−183W coupling constants in Hz.
d
e
f
Data taken from ref 1. Data taken from ref 11. Values corresponding
g
h
to the C−N stretching frequencies. Values for isomer 13a. Values
for isomer 13b.
assumed for this molecule, with a cisoid arrangement of the Cp
ligands, as determined crystallographically for 6.11 Of particular
relevance in this respect are the values of the C−O stretching
frequencies in these compounds [1908 (3) < 1914 (5) < 1926
(6) cm−1], which suggest that the phenolato ligand has a π-
donor ability intermediate between those of the hydroxo
(stronger donor) and thiolato (weaker donor) ligands.
Moreover, 5 displays a single 31P NMR resonance with
medium to high one-bond P−W couplings (381 and 272 Hz)
comparable to those measured for 3 (372 and 281 Hz) and 6
(370 and 266 Hz),11 in agreement with the similar and
relatively low-coordination environments of the metal centers
in all of these molecules.12
Compound 1 does not react with p-toluidine, nor does it in
the presence of [FeCp2]BF4, the only product formed being the
ubiquitous oxohydride 4. In contrast, compound 2 reacts
rapidly with p-toluidine in the presence of the same oxidant to
give the imidohydride derivative [W2Cp2(μ-H)(Np-tol)(μ-
PPh2)2(CO)]BF4 (7) in good yield (Chart 1). Compound 7
is structurally related to the oxohydride 4 and to the
11
sulfidohydride [W2Cp2(μ-H)(S)(μ-PPh2)2(CO)]BF4 and
can be analogously deprotonated to give a neutral derivative.
Indeed, the addition of the strong base 1,8-diazabicycloundec-
7-ene (DBU) to dichloromethane solutions of 7 gives the imido
complex [W2Cp2(Np-tol)(μ-PPh2)2(CO)] (8) quantitatively
(Chart 1).
We finally examined the reactivity of the hydroxycarbyne 1
toward several molecules having P−H bonds. Although no
Structural Characterization of the Imido Compounds
7 and 8. The cation in compound 7 (Figure 1 and Table 2) is
built from two cisoid WCp fragments bridged by a hydride and
two transoid PPh2 ligands, the latter defining a flat W2P2
C
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
previously that the presence of three monodentate bridging
ligands causes a systematic decrease of the intermetallic
distances. Indeed, this is the case of the isoelectronic and
isostructural complexes [W2Cp2(μ-COMe)(μ-PPh2)2(CO)2]-
BF4 (2.9020(5) Å) and [W2Cp2(μ-COMe)(μ-PPh2)2(μ-
dmpm)]BF4 (2.917(1) Å).6a
The spectroscopic data available in solution for 7 (Table 1
and Experimental Section) are fully consistent with its solid-
state structure and indicative of its close structural relationship
with the oxohydride 4 and the sulfido hydride [W2Cp2(μ-H)(μ-
PPh2)2(S)(CO)]BF4.11 For instance, 7 displays a single 31P
NMR resonance (δ 40.8 ppm, JPW = 267, 248 Hz) with
chemical shift and P−W couplings comparable to those of 4 (δ
31.3 ppm, JPW = 280, 246 Hz)1 and the sulfido hydride complex
(δ 36.8 ppm, JPW = 244, 228 Hz).11 Its IR spectrum displays a
C−O stretching band (1959 cm−1) significantly less energetic
than those in the mentioned complexes (cf. 1977 cm−1 for 4),
reflecting the stronger π-donor ability of the imido ligand.
Finally, the presence of a bridging hydride ligand in 7 is clearly
denoted by the appearance of a strongly shielded resonance at
Figure 1. ORTEP diagram (30% probability) of the cation in
compound 7 with H atoms (except the hydride ligand) and Ph and p-
tol groups (except their C1 atoms) omitted for clarity.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Compound 7
W(1)−W(2)
W(1)−P(1)
W(1)−P(2)
W(2)−P(1)
W(2)−P(2)
W(1)−C(1)
C(1)−O(1)
W(2)−N(1)
N(1)−C(36)
2.9135(8)
2.374(2)
2.388(2)
2.469(2)
2.474(2)
1.980(10)
1.164(10)
1.759(8)
1.405(10)
W(1)−P(1)−W(2)
W(1)−P(2)−W(2)
C(1)−W(1)−W(2)
C(1)−W(1)−P(1)
C(1)−W(1)−P(2)
N(1)−W(2)−W(1)
N(1)−W(2)−P(1)
N(1)−W(2)−P(2)
W(2)−N(1)−C(36)
W(1)−C(1)−O(1)
73.93(6)
73.61(6)
80.9(2)
85.2(2)
84.3(2)
104.6(2)
99.1(2)
98.8(2)
167.2(6)
176.3(7)
1
−9.18 ppm in its H NMR spectrum, with chemical shift and
P−H and P−W couplings comparable to those reported for 4
and the mentioned sulfido hydride complex.
The spectroscopic data for the neutral imido complex 8 also
are comparable to those of the neutral oxo and sulfido
complexes [W2Cp2(μ-PPh2)2(E)(CO)] (E = O,1 S11); then, a
similar structure is to be assumed for this molecule, with a
cisoid arrangement of the Cp ligands. Of particular significance
in this respect is that the 31P chemical shifts and one-bond P−
W couplings of all of these complexes are remarkably similar [δ
109.2 ppm, JPW = 385, 304 Hz (8), δ 102.2 ppm, JPW = 381, 322
Hz (E = O)]. Moreover, the values of the P−W couplings in 8
are substantially higher than those in its precursor 7, in
agreement with the reduction of the coordination number at
the metal centers operated upon deprotonation.12 The IR
spectrum of 8 displays one C−O stretching band at 1833 cm−1,
a figure that again is substantially lower than those measured for
the related oxo and sulfido complexes (1858 and 1863 cm−1,
respectively), once more denoting the superior π-donor ability
of the imido ligand.
We should note that the strong spectroscopic similarities
found between the imido complexes 7 and 8 and their cationic
and neutral oxo and sulfido counterparts reveals that the π-
bonding contribution (ligand to metal) in the latter oxo and
sulfido complexes, although lower than the corresponding
contribution in the imido complexes, might be greater than
initially suspected,1,11 this implying that the intermetallic bond
order in these chalcogeno complexes might actually be
intermediate between one and two (rather than two), a matter
that we have discussed previously for the isoelectronic oxo
complexes [Mo2Cp2(μ-CPh)(μ-PCy2)(O)(CO)].10
Structural Characterization of Compounds 9 and 10.
The presence of a terminal carbonyl ligand in 9 is clearly
evidenced by the appearance in the IR spectrum of a C−O
stretching band at 1895 cm−1, with a frequency comparable to
those measured for related complexes of the type [M2Cp2(κ2-
L2)(μ-PPh2)2(CO)]+ (L2 = 3-electron bidentate ligand, M =
Mo,18 W).11 The appearance of three resonances in the
31P{1H} NMR spectrum (Table 1) establish the incorporation
of the PH2Cy ligand, in a way that renders inequivalent PPh2
groups, thus discarding a structure with a bridging hydride
ligand comparable to that of 7. Full assignment of these
resonances could be made by considering the number and
rhombus, with the coordination sphere of the metals being
completed with either CO or Np-tol terminal ligands, almost
parallel to each other, with the first one leaning toward the
intermetallic center (C−W−W 80.9(2)°) and the second one
pointing away from it (N−W−W 104.6(2)°). The W(2)−N(1)
length of 1.759(8) Å is consistent with the formulation of a
triple bond between these atoms, this value being comparable
to those measured in related complexes having WN bonds
such as [W2Cp2(μ-PPh2)2(κ1-N2CPh2)(CO)],6a [W2Cp2{NC-
(CMe2)(Ar)}(μ-CO)(CO)3], [Mo2Cp*2{NC(CMe2)(Ph)}(μ-
CO)2(CO)2],13 [MCp*ClMe2(NtBu)] (M = Mo and W),14
[WTp′(CO)2 (NR)]PF6 (Tp′
= hydrotris(3, 5-
15
t
dimethylpyrazolyl)borate; R = Ph, Bu), or [W(NCy)Cl-
(PMe3)4]BPh4,16 in the range 1.71−1.79 Å. This bond
multiplicity is also supported by the almost linear conformation
of the W(2)−N(1)−C(36) chain (167.2(6)°), as expected for a
sp-hybridized N atom. In fact, the small deviation from linearity
observed might be caused by an incipient steric clash between
one of the phenyl groups of the PPh2 ligands and the aromatic
ring of the imido group. As observed for the complexes
mentioned above, the imido group in 7 exerts a strong labilizing
effect. As a result, the P atoms bridge the metal atoms
somewhat asymmetrically (Δd ca. 0.1 Å), being closer to the
W(CO) fragment, as expected from the different donor ability
of the terminal ligands involved (CO vs Np-tol). This effect can
be also noticed in the W(2)−Cp bonding, with a particularly
larger elongation of the bond involving the C atom trans to the
N atom (W(2)−C(7) = 2.377(10) Å). In all, the NR group
would be acting as a four-electron donor, and therefore a single
metal−metal bond should be formulated for this cation under
the effective atomic number (EAN) formalism. This is
consistent with the intermetallic distance of 2.9135(8) Å,
which still might be viewed as somewhat short for an electron-
precise molecule. However, we6a and others17 have found
D
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
values of the observed P−W, P−H, and P−P couplings; thus,
the most shielded signal (−25.5 ppm) was easily assigned to
the terminal PH2Cy ligand, on the basis of its coupling to a
single 183W nucleus, two P−H hydrogen atoms (1JPH = 370 Hz)
and a hydride ligand (2JPH ca. 70 Hz). In addition, by recalling
Scheme 3
2
the general trends established for the absolute values of JXY in
complexes of the type [MCpXYL2],12,19 (Jcis > Jtrans), we can
identify the PPh2 resonance displaying larger P−P coupling (δ
2
100.6 ppm, JPP = 20 Hz) as the one corresponding to the
group positioned cis to the phosphine ligand. Finally, the
presence of a terminal hydride ligand is corroborated by the
1
appearance of a poorly shielded resonance in the H NMR
spectrum at −0.79 ppm, coupled to the three P atoms of the
cation (JHP = 67, 36, and 11 Hz). This in turn implies that the
coordination numbers of the two metal atoms differ by one
unit, which is consistent with the large difference between the
P−W couplings of each of the PPh2 groups (Table 1). It should
be stressed that the cation 9 is structurally related to the
hydride cations [W2Cp2(H)(μ-PR2)2(CO)2]+ (R = Ph, Et)
initially formed upon protonation of the neutral dicarbonyls
trans-[W2Cp2(μ-PR2)2(CO)2]. These dicarbonyl cations also
display poorly shielded hydride resonances (cf. −0.42 ppm, JPP
19 and 12 Hz when R = Ph).8 There are, however, two
fundamental differences between these species and 9: First,
they presumably display a transoid arrangement of the
constituting WCp fragments, in contrast to the cis arrangement
presumed for 9. Second, they are thermally unstable and
rearrange at room temperature to the hydride-bridged isomers
[W2Cp2(μ-H)(μ-PR2)(CO)2]+, with a cis arrangement of the
carbonyl ligands (confirmed crystallographically in the PPh2
derivative), a structure comparable to that of the imido hydride
7. Interestingly, compound 9 proved to be stable in refluxing
dichloromethane solution for 4 h.
The neutral complex 10 displays a C−O stretching band at
1855 cm−1, a figure some 40 cm−1 lower than the
corresponding one in its cationic precursor as expected and
also lower than the average figure of 1899 cm−1 found in the
related dicarbonyl complex cis-[W2Cp2(μ-PPh2)2(CO)2],8 as
anticipated for the replacement of a carbonyl group with a
poorer acceptor PH2Cy ligand. The two PPh2 groups are now
equivalent and give rise to a resonance at 81.7 ppm (cf. 74.3
ppm in the mentioned dicarbonyl complex), while the PH2Cy
group gives rise to a relatively shielded signal at 14.9 ppm
retaining a large coupling to two protons (1JPH = 340 Hz). The
coordination numbers in this structure are now the same for
both W atoms, which is reflected in all P−W couplings having
high and comparable values above 300 Hz, in contrast to the
dissimilar values observed in the precursor 9 (Table 1).
Pathways in the Reactions of 1 with HERn Molecules.
As we have discussed above, compound 1 reacts with H2O,
HSPh, and PH2Cy in the absence of oxidant to yield, in all
cases, products in which the hydrogen atom of the
hydroxycarbyne ligand either migrates to one of the metals or
is eliminated along with one of the H atoms of the incoming
molecule, presumably in the form of H2. In any case, the
products obtained display invariably a cis arrangement of the
newly generated CO group and the incoming ligand. Although
we have detected no intermediate species in these reactions, the
above results can be rationalized on the basis of the elementary
steps collected in the Scheme 3.
between a PPh2 group and the COH bridging ligand. This
would leave the hydroxycarbyne and the incoming molecule in
a relative cis disposition (intermediate A), thus paralleling the
carbonylation reactions of the bis(phosphide) complexes
[M2Cp2(μ-PR′2)2(μ-CO)] (M = Mo, W; R = alkyl or aryl)
to give specifically cis-dicarbonyl derivatives20 and the addition
of CO or isocyanides to the methoxycarbyne complexes
[M2Cp2(μ-COMe)(μ-PR′2)2]+ (M = Mo, R = Et; M = W, R
= Ph).6a We must note that the displacement of a related
methoxycarbyne ligand to an almost terminal position induced
upon ligand coordination has been observed previously in the
carbonylation of the unsaturated complex [Mo2Cp2(μ-COMe)-
(μ-PCy2)(μ-CO)].7d Under this view, the failure of phenol and
p-toluidine to react with 1 possibly would be related to their
poor donor properties, disfavoring the initial coordination step
to give an intermediate of type A. The next step in these
reactions would involve the transfer of the H atom of the
hydroxycarbyne ligand to the dimetal center, which in the case
of PH2Cy would directly give the final product 9. This process
would be analogous to the observed isomerization of the
hydroxycarbyne complex salts [Mo2Cp2(μ-COH)(μ-PEt2)2]-
BF4 and [Mo2Cp2(μ-COH)(μ-COMe)(μ-PCy2)]BF4 to give
the corresponding hydride-carbonyl isomers.4a However, the
water and PhSH analogues of 9 (undetected complexes of type
B) would not be stable enough, likely as a result of the still
modest donor properties of these ligands. Instead, they would
evolve rapidly via dehydrogenation to give the hydroxo (3) and
thiolato (6) derivatives, respectively.
Pathways in the Redox-Induced Reactions of 1. The
phenolate and imido complexes 5 and 7 could only be obtained
via one-electron oxidation of the neutral monocarbonyl 2, in
reactions that could not be replicated using the hydroxycarbyne
1 as starting material. In fact, the reactions of the latter
compound with these reagents led only to the oxohydride 4,
presumably as a consequence of the relatively larger amounts of
trace water present in the reactions of 1, due to the additional
synthetic steps required to prepare this complex. However, the
thiolato 6 could be obtained from either the hydroxycarbyne 1
or the carbonyl 2 upon one-electron oxidation. Then, it seems
reasonable to assume that the redox-induced reactions of 1 and
2 likely share a common intermediate (Scheme 4). Expectedly,
the dicationic radical 1+ following from the one-electron
oxidation of the hydroxycarbyne 1 would be extremely acidic,
therefore being rapidly deprotonated (by the counterion or the
added reagent), thus yielding a radical 2+ identical to the one-
electron oxidation product of the carbonyl-bridged complex 2.
The first step in all these reactions would be the coordination
of the incoming ligand to the unsaturated dimetal center, which
would occur preferentially at the less hindered position, that is,
E
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
to understand that the removal of one electron from 2 involves
a rearrangement of the carbonyl ligand and some weakening of
the intermetallic interaction, the latter effect being against
qualitative predictions based on the EAN formalism. Indeed,
the optimized structure for 2+ (Figure 2) displays a carbonyl
Scheme 4
Figure 2. DFT-optimized structure of the cation in compound 2+ with
H atoms omitted (left) and total spin density for the same cation
(right).
ligand in a linear semibridging fashion, weakly bound to the W2
atom (W2−C = 2.381 Å), while the intermetallic distance of
2.561 Å is only ca. 0.03 Å longer than in the precursor 2 (2.535
Å). An analysis of the electron density in these molecules under
the Atoms in Molecules theory22 gives a similar picture, with
the density at the intermetallic bond critical point being just
slightly reduced upon oxidation, from 0.665 (2) to 0.631 e Å−3
(2+) (cf. 0.624 and 0.553 e Å−3, respectively, in the benzylidyne
complexes).10 Concerning its potential reactivity, we note that
the LUMO in 2+ is largely located at the dimetal center
(actually having δMM bonding character, see the Supporting
Information), so it is the total spin density, higher at the less
protected W2 atom (Figure 2, right). This allows us to
understand the reactivity of 2+ toward HERn molecules as
centered at that metal atom, inducing the homolytic cleavage of
the single E−H bonds to rapidly give ERn derivatives with
release of H atoms (Scheme 4). This would yield stable
compounds except for the imido derivative [W2Cp2(μ-
PPh2)2(NHp-tol)(CO)]BF4 (C in Scheme 4), which rapidly
would undergo an oxidative addition of the N−H bond to give
the imido hydride 7, in a process completely analogous to the
(slower) conversion of the hydroxo species 3 into its
oxohydride isomer 4.
Reactions of Compound 1 with Monodentate
Ligands. In our previous studies on the reactivity of 30-
electron methoxycarbyne complexes we found that these
unsaturated molecules are usually quite reactive toward simple
two-electron donors such as CO or isocyanides, to give
electron-precise derivatives in most cases.6,7d Thus, we
anticipated that compound 1 would react analogously. Indeed,
although compound 1 failed to react with CO (1 atm) at room
temperature, rapid reactions were observed with acetonitrile
and isocyanides. However, all of these reactions involved the
cleavage of the O−H bond of the hydroxycarbyne ligand.
Compound 1 is instantaneously and selectively transformed
into the α-diiminate complex salt [W2Cp2(μ-PPh2)2(μ-N:N,N′-
N2HC2Me2)(CO)]BF4 (11) by just dissolving it in acetonitrile
(Chart 2). The formation of this compound involves the
reductive C−C coupling of two acetonitrile molecules
accompanied by transfer of the hydroxycarbyne proton to
one of the nitrogen atoms, to yield the diiminate ligand. There
are several precedents for this relatively unusual coupling of
Radical 2+ thus would actually be the active species triggering
the fast reactions of 1 and 2 with all HERn molecules, including
water. We have recently reported a related redox-induced
chemistry of the benzylidyne complex [Mo2Cp2(μ-CPh)(μ-
PCy2)(μ-CO)].10 According to density functional theory
(DFT) calculations, the removal of one electron in the latter
complex yields a radical [Mo2Cp2(μ-CPh)(μ-PCy2)(μ-CO)]+
with a weakened intermetallic bond and a linear semibridging
carbonyl, while both the LUMO and most of the unpaired
electron density are located at the same molybdenum atom,
thus accounting for its reactivity toward simple HERn reagents
(thiols, phosphines, alcohols, etc.).10 To gain insight into the
behavior of the radical 2+ involved in the redox-induced
reactions of 1 and 2, we performed similar DFT21 calculations
on both 2 and 2+ (Table 3) (see Experimental Section and
Table 3. Selected Bond Lengths (Å) and Angles (deg) for the
DFT-Optimized Structures of 2 and 2+
2
2+
2
2+
W1−W2
W1−P1
W2−P1
W1−P2
W−P2
W1−C1
W2−C1
C1−O1
2.535
2.409
2.407
2.407
2.409
2.094
2.092
1.206
2.561
2.430
2.425
2.418
2.418
1.983
2.381
1.184
W1−P1−W2
W2−W1−C1
W1−W2−C1
P1−W1−C1
W1−C1−O1
W2−C1−O1
63.5
52.7
63.8
61.7
52.8
47.1
92.1
97.3
142.7
142.8
163.0
125.8
Supporting Information for details). The emerging picture is
similar to that of the benzylidyne complexes, with only minor
differences. First, we found that the geometrical and electronic
structure computed for 2 is comparable to that previously
calculated for the dimolybdenum complex [Mo2Cp2(μ-
PEt2)2(μ-CO)]4b and deserves no particular comment, except
to stress that the triple W−W bond in 2 can be similarly
described as having one σ and two δ components (with one of
the latter also having some bonding character to the bridging
CO ligand), while the HOMO is a bonding orbital having σ
Mo−CO character. The nature of these orbitals thus allow us
F
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
preventing a detailed analysis of the structural results, the
connectivity and overall conformation of the molecule was
confirmed through a single-crystal X-ray diffraction study
(Figure 3).25 The cation in 11 is built up from two transoid
Chart 2
acetonitrile ligands.23,24 Of particular relevance, due to the
similar coordination mode of the ligand generated, is the
formation of the binuclear complexes: [Re2X3(μ-N:N,N′-
N2HC2Me2)(μ-dppm)2(NCMe)]PF6 (X = Cl, Br),24i [W2(μ-
NAr′)(μ-N:N,N′-N2C2Me2)(OCMe2CF3)4] (Ar′ = Xylil),24b
and [W2(μ-N:N,N′-N2HC2Me2)(μ-OiPr)2(OiPr)5].24f Yet, it is
unusual that such reactions can take place under mild
conditions, as observed for 11. Although we have observed
no intermediates in the formation of 11, it is likely that this
reaction might evolve initially through an unstable hydride
intermediate similar to the phosphine complex 9, which as a
result of the poor donor properties of acetonitrile and its small
size would add a second molecule of ligand, thus triggering the
coupling and migration steps leading to 11.
The reaction of 1 with isocyanides also involved the
incorporation of two molecules of reagent but led to no C−
C coupled products; moreover they were quite sensitive to the
particular isocyanide used and even to the experimental
conditions. Thus, compound 1 reacted rapidly with excess
CNtBu to give the 32-electron hydride [W2Cp2(H)(μ-
PPh2)2(μ-CNtBu)(CNtBu)]BF4 (12) (Chart 2), a rather
unstable product following from the addition of two isocyanide
molecules, release of CO, and migration of the hydroxycarbyne
proton to one of the metal atoms. In contrast, the reaction with
excess CNp-tol led to more stable products, identified as the
electron-precise aminocarbyne complex salt [W2Cp2{μ-CN(H)
p-tol}(μ-PPh2)2(CNp-tol)(CO)]BF4 (13) (Chart 2), which is
obtained as an equilibrium mixture of two isomers (13a/13b)
differing in the orientation of the aminocarbyne ligand in the
asymmetric dimetal center (Chart 2). The formation of these
products also requires the incorporation of two isocyanide
molecules, but now decarbonylation does not take place, and
the hydroxycarbyne proton is eventually incorporated to one of
the isocyanide molecules to yield an aminocarbyne ligand.
Interestingly, the reaction of 1 with stoichiometric amounts of
CNtBu gave a mixture of unreacted 1, the hydride 12, and
several other species, two of which might be analogous to the
isomers 13, as judged from their similar 31P NMR resonances.
Unfortunately, we could not find experimental conditions to
purify or prepare these products more selectively. In any case,
these observations indicate that the structural differences
between compounds 12 and 13 are not uniquely of
thermodynamic origin but also derived from kinetic effects.
Structural Characterization of Compound 11. Although
the quality of the crystals of compound 11 was very poor,
Figure 3. PLUTO diagram (30% probability) of the cation in
compound 11 with H atoms and Ph groups (except their C1 atoms)
omitted.
WCp moieties connected by three bridging ligands: two PPh2
ligands defining an almost flat W2P2 rhombus and the diiminate
group, also binding one of the metal centers in a terminal way
via its imine N atom. The coordination sphere of the other
metal atom is completed with a carbonyl ligand slightly bent
over the metal−metal bond. The intermetallic separation of
2.856(4) Å is relatively short for the single W−W bond that
should be formulated for this 34-electron cation according to
the EAN formalism, a fact that can be attributed to the presence
of three bridging ligands, with one of them (N) having a small
covalent radius. The overall arrangement of ligands in the
cation of 11 implies that one of the metals exhibits the typical
four-legged piano stool coordination geometry, while the
second metal displays a less common trigonal bipyramidal
environment. We have found this sort of geometry in different
dicarbonyl complexes of the type [M2Cp2(μ-PR2)(μ-X)(μ-
Y)(CO)2] having three or more atoms bridging the dimetal
unit.26,27 We finally note that the diiminate ligand displays an
almost perfectly planar disposition, perpendicular to the Mo2P2
plane, analogous to those found in the Re2 and W2 complexes
mentioned above.
The spectroscopic data in solution for 11 are consistent with
the retention in solution of the solid-state structure. Thus, the
presence of a terminal carbonyl ligand is clearly denoted by the
appearance of a C−O stretching band at 1912 cm−1 in the
corresponding IR spectrum and a deshielded 13C NMR
resonance at 227.3 ppm, while the equivalent PPh2 bridging
ligands give rise to a single 31P resonance at −25.1 ppm. The
latter represents a rather strong shielding for a PR2 ligand
bridging a M−M bond.28 However, we have previously
observed large 31P nuclear shieldings in related 34-electron
8
Mo2 and W2 cations of the type [M2Cp2(μ-H)(μ-PR2)2L2]+
and [M2(μ-COMe)(μ-PR2)2L2],6a also displaying flat M2P2
cores. As expected, the P−W couplings in 11 are much lower
than in 1, consistent with the increased number of donor atoms
around the W atoms.12 Finally, the presence of the diiminate
ligand is denoted by the appearance of inequivalent CN (δC
G
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
159.7 and 153.9 ppm) and methyl resonances (δC 20.1 and 18.0
ppm). Although the nitrogen-bound H atom was not located in
the crystallographic study, due to the low quality of the data,
the presence of an N−H group is fully supported by the
appearance of a characteristically deshielded resonance in the
1H NMR spectrum (12.7 ppm) and also by the presence of a
weak N−H stretching band at 3247 cm−1 in the corresponding
solid-state IR spectrum.
Structural Characterization of Compound 12. The
incorporation of two CNtBu ligands in 12 is confirmed by the
appearance of two tBu resonances with the expected intensities
in the 1H NMR spectrum. The equivalent PPh2 groups give rise
to a single 31P NMR resonance at δP 60.5 ppm with
substantially different one-bond P−W couplings (JPW = 319
and 245 Hz), indicative of significant differences in the nature
of the terminal ligands at the dimetal center. The migration of
the hydroxycarbyne proton to one of the metal atoms to form a
terminal hydride ligand is firmly established by the appearance
of a 1H NMR resonance at 3.64 ppm, and the lack of diagnostic
O−H or N−H bands in the solid-state IR spectrum. The
unusually low shielding of this resonance is likely derived from
the strong anisotropy of the double metal−metal bond that
should be formulated for this cation according to the EAN
formalism. For instance, we have shown previously that the
resonance of the bridging hydride in the 32-electron cations
220−240 ppm for the type II ligands in complexes
[MoCp2(CNR)]34 and [WCp*(CNR)2(CNEt2)]).35 Thus a
linear bridging coordination is proposed for the second
isocyanide ligand in 12, which in turn is consistent with the
presence of a terminal hydride in the molecule.
We should note that, in any case, the structure of 12 is highly
unexpected after considering that related Mo2 and W2 hydrides
previously reported invariably display hydride-bridged struc-
tures of the type [M2Cp2(μ-H)(μ-PR)2L2]+ with terminal L
ligands (L = CO, CNtBu) arranged almost parallel to each
other, these including the crystallographically characterized
cations [W2Cp2(μ-H)(μ-PPh2)2(CO)2]+ and [Mo2Cp2(μ-
H)(μ-PCy2)2(CO)(CNtBu)]+.8 The phosphine hydride 9 still
represents a third isomeric form in this family of 32-electron
binuclear hydrides, as noted above. At present, however, we
cannot give a satisfactory explanation for the observed
structural preferences in these unsaturated hydrides.
Structural Characterization of the Aminocarbyne
Complex 13. The spectroscopic data for both isomers of
compound 13 are similar to each other (Table 1 and
Experimental Section), therefore indicating a close structural
relationship. Their 31P NMR spectra display a single and
strongly shielded resonance at ca. −25 ppm in each case, which
seems to be a characteristic feature of cations of the type
[M2Cp2(μ-X)(μ-PR2)2L2]+ having flat M2P2 cores, as noted
above (cf. −25.1 ppm for 11). The presence of a terminal
isocyanide ligand in each case is denoted by the appearance of a
high frequency C−N stretch at ca. 2110 cm−1 in the IR
spectrum and a poorly deshielded resonance at ca. 165 ppm in
the 13C{1H} NMR spectrum. In contrast, the aminocarbyne
ligands display a much more deshielded 13C resonance at ca.
315 ppm. For comparison, we note that the latter figures are
quite similar to those measured in related aminocarbyne
complexes such as [W2Cp2(μ-CNHMe)(μ-H)(CO)4] (317.4
ppm)36 and in the crystallographically characterized [W2Cp2{μ-
CNH(Xyl)}(μ-PCy2)(CO)(CNXyl)] (ca. 336 ppm).37 The
carbonyl ligand in the isomers of 13 gives rise to a strong C−O
stretching band at 1960 cm−1 and a deshielded 13C resonance at
ca. 230 ppm, as expected. Finally, the presence of a N−H bond
in these complexes is deduced from the appearance of a
deshielded 1H NMR resonance at ca. 9.4 ppm and a
characteristic high-frequency band in the solid-state IR
spectrum (3310 cm−1).
[W2Cp2(μ-H)(μ-PR2)(μ-Ph2PCH2PPh2)(CO)2]2+ (PR2
=
+
PPh2, PHCy) is displaced from ca. −5 to 3 ppm by just
exchanging the relative positions of the PR2 and H ligands.29
The IR spectrum of 12 displays two C−N stretching bands at
2140 and 1950 cm−1. The more energetic band is characteristic
of terminal isocyanide ligands with a linear disposition in a
cationic complex (I in Chart 3), a proposal consistent with the
Chart 3
To explain the presence of isomers in the solutions of 13, we
must recall that the structure and electronic distribution within
aminocarbyne ligands typically is best described by the
contribution of two canonical forms: an aminocarbyne form
involving π bonding between C and the metal atoms (R1) and
an iminium-type form (R2) involving π bonding between the C
and N atoms (Chart 4).38 This implies that the rotation around
the C−N bond in these complexes is restricted, thus allowing
for the existence of two slowly interconverting isomers if the
presence of a moderately deshielded resonance at 199.0 ppm in
the 13C NMR spectrum. The less energetic C−N stretch might
be associated with at least two coordination modes of the
isocyanide ligand: either a bent terminal mode (II in Chart 3)
usually leading to C−N stretches in the range 1800−1900 cm−1
or a linear bridging mode (III in Chart 3), with the bent
bridging mode (IV in Chart 3) being discarded since it usually
leads to less energetic C−N stretches (in the range 1580−1880
cm−1).30 Indeed, the complexes [Pd2Cl2{μ-CN(2,6-
C6 H3 Me2 )}2 (py)2 ],3 1 [Pd2 (η5 -C5 Ph5 ){μ-CN(2,6-
C6H3Me2)}2],32 and [Pd4(μ-OAc)4(μ-CNtBu)4],33 all of them
having linear bridging CNR groups (as determined by
crystallographic studies), exhibit C−N stretches in the range
1956−1976 cm−1. On the other hand, the high chemical shift
for the second isocyanide ligand in 12 (δC 255.1 ppm) gives a
slightly better match with a coordination of type III (cf. 220−
260 ppm for different complexes with type III ligands,30 but
Chart 4
H
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
+
̀
two metal centers are otherwise inequivalent, as is the case with
compound 13.
COMe)(μ-PR2)2] (M W, R = Ph; M = Mo, R = Et) with
CNtBu.6a This second pathway would also be operative at some
extent when using stoichiometric amounts of CNtBu in these
reactions, as noted above. We should finally note that although
the insertion of isocyanide ligands in M−H bonds is well-
documented in reactions of molecules having unsaturated M2H
centers, these processes usually lead to formimidoyl derivatives
(-C(H)NR).39 However, there is a number of instances where
the isolated products of these reactions are the corresponding
aminocarbyne derivatives,36−38,39a presumably formed in some
cases through deprotonation/protonation processes, a mecha-
nism that cannot be excluded for the cationic intermediates of
type B.
Pathways in the Reactions of Compound 1 with
Isocyanides. Although we have detected no intermediates in
the reactions of 1 with isocyanides, the nature of the products
obtained can be rationalized by considering the participation of
species related to those proposed for the reactions with HERn
molecules discussed above (Scheme 5). The first two steps
Scheme 5
CONCLUSION
■
The reactivity of the hydroxycarbyne complex salt [W2Cp2(μ-
COH)(μ-PPh2)2]BF4 (1) invariably involves the cleavage of its
O−H bond, to give products strongly dependent on the added
reagent and experimental conditions. Most of the reactions with
potential donor molecules L seem to be initiated with the
coordination of L to the unsaturated cation and H-transfer of
the hydroxycarbyne proton to the dimetal site, to give 32-
electron hydride carbonyl complexes of the type [W2Cp2(H)-
(μ-PPh2)2(CO)L]+, which are stable only when L is a
phosphine ligand. When L is an HERn molecule such as H2O
and HSPh, then cleavage of the E−H bond also takes place to
give hidroxo and thiolato derivatives of the type [W2Cp2(ERn)-
(μ-PPh2)2(CO)]+ and hydrogen. These reactions are greatly
accelerated in the presence of stoichiometric amounts of the
oxidant [FeCp2]BF4 and can be replicated under the latter
conditions when using the carbonyl-bridged complex
[W2Cp2(μ-PPh2)2(μ-CO)] (2) instead. This equivalence can
be explained by assuming that the dication following from one-
electron oxidation of 1 would be extremely acidic and therefore
rapidly deprotonated to give a radical [W2Cp2(μ-PPh2)2(μ-
CO)]+ (2+) identical to that following from the one-electron
oxidation of 2. Radical 2+ displays a slightly weakened
intermetallic bond and a linear semibridging carbonyl,
according to DFT calculations; moreover, both the LUMO
and most of the unpaired electron density in this cation are
located at the dimetal center, thus explaining its fast induction
of E−H bond cleavages when faced to HERn molecules, to give
[W2Cp2(ERn)(μ-PPh2)2(CO)]+ derivatives (ERn = OH, SPh,
OPh, NHp-tol) and hydrogen. When L= NCMe or CNR,
however, the [W2Cp2(H)(μ-PPh2)2(CO)L]+ intermediates
evolve through the addition of a second molecule of L, in
processes strongly dependent on L and experimental
conditions, usually accompanied by H-transfer to L and other
rearrangements, such as the reductive C−C coupling between
acetonitrile molecules, to give products containing amino-
carbyne or diiminate ligands, as exemplified by the formation of
the complexes [W2Cp2{μ-CN(H)p-tol}(μ-PPh2)2(CNp-tol)-
(CO)]+ and [W2Cp2(μ-PPh2)2(μ-N:N,N′-N2HC2Me2)(CO)]+
respectively.
would analogously involve coordination of a molecule of
reagent to yield a hydroxycarbyne intermediate of type A,
followed by migration of the hydroxycarbyne proton to one of
the metals, then rendering a hydride intermediate B structurally
related to the phosphine complex 9. From here on, the
evolution of these intermediates would depend critically on the
particular isocyanide. For the more basic CNtBu ligand, the
coordination of a second isocyanide molecule would be fast
when present in excess, before any rearrangement can possibly
take place, then giving a bis(isocyanide) intermediate D that
would evolve to the final product 12 after spontaneous
decarbonylation and terminal to bridging rearrangement of a
isocyanide ligand. The less basic CNp-tol ligand would react
more slowly, so that the insertion of the coordinated isocyanide
in the M−H bond at intermediate B might occur before a
second molecule of ligand reaches the dimetal center, thus
yielding a carbonyl/aminocarbyne intermediate A′ analogous to
the isocyanide/hydroxycarbyne intermediate A, which then
would add the second CNp-tol molecule to eventually give the
final product 13, in a process comparable to those observed in
the reactions of the methoxycarbyne cations [M2Cp2(μ-
EXPERIMENTAL SECTION
■
General Procedures. All reactions and manipulations were carried
out under a nitrogen atmosphere using standard Schlenk techniques.
Solvents were purified according to literature procedures40 and
distilled under nitrogen prior to use. Petroleum ether refers to that
fraction distilling in the range 338−343 K. Compounds [W2Cp2(μ-
COH)(μ-PPh2)2]BF4 (1),1 [W2Cp2(μ-PPh2)2(μ-CO)] (2),20 and
41
[FeCp2]BF4 were prepared as described previously. All other
I
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
reagents were obtained from the usual commercial suppliers and used
as received. Filtrations were carried out through diatomaceous earth.
Chromatographic separations were carried out using jacketed columns
cooled by tap water (ca. 288 K) or kept at the desired temperature
with a cryostat. Commercial aluminum oxide (Aldrich, activity I, 150
mesh) was degassed under vacuum prior to use. The latter was
afterward mixed under nitrogen with the appropriate amount of water
to reach the activity desired. IR stretching frequencies of C−O, C−N,
N−H, and B−F bonds were measured either in solution (using CaF2
windows) or in Nujol mulls (using NaCl windows), are referred to as
ν(CO), ν(CN), ν(NH), or ν(BF), and are given in cm−1. Nuclear
magnetic resonance (NMR) spectra were routinely recorded at 300.13
(1H), 75.46 MHz (13C{1H}), and 121.50 MHz (31P{1H}) at 290 K in
CD2Cl2 solutions unless otherwise stated. Chemical shifts (δ) are
given in ppm, relative to internal tetramethylsilane (1H, 13C) or
external 85% aqueous H3PO4 solutions (31P). Coupling constants (J)
are given in hertz.
vacuum (0.050 g, 64%). Anal. Calcd for C41H44BF4OP3W2: C, 44.76;
H, 4.03. Found: C, 44.31; H, 3.70. IR (Nujol): ν(PH) 2363 (w);
ν(CO) 1893 (s); ν(BF) 1050 (s, br). 1H NMR: δ 8.11, 7.88 (2m, 2 ×
2H, PPh), 7.69−7.29 (m, 12H, PPh), 6.82, 6.73 (2m, 2 × 2H, PPh),
5.57, 4.91 (2s, 2 × 5H, Cp), 4.78 (d, JHP = 365, 2H, PH2), 1.54−0.66
(m, 11H, Cy), −0.79 (ddd, JHP = 67, 36, 11, 1H, W−H).
Preparation of [W2Cp2(μ-PPh2)2(CO)(PH2Cy)] (10). The proce-
dure and workup was analogous to that described for 8, but using
compound 9 (0.050 g, 0.045 mmol) and 30 μL of DBU (0.200 mmol).
Elution with petroleum ether gave a pale green fraction yielding, after
removal of solvent, compound 10 as a green solid (0.043 g, 94%).
Anal. Calcd for C41H43OP3W2: C, 48.64; H, 4.28. Found: C, 48.20; H,
4.17. IR (Nujol): ν(PH) 2290 (w); ν(CO) 1858 (s). 1H NMR
(200.13 MHz): δ 7.92 (m, 4H, PPh), 7.47−7.28 (m, 6H, PPh), 7.17−
7.01 (m, 6H, PPh), 6.64 (m, 4H, PPh), 4.83 (s, 5H, Cp), 4.51(dt, JHP
= 3.5, 1, 5H, Cp), 3.89 (dm, JHP = 340, 2H, PH2), 1.35−0.30 (m, 11H,
Cy).
Preparation of [W2Cp2(OPh)(μ-PPh2)2(CO)]BF4 (5). Freshly
sublimed phenol (ca. 0.050 g, 0.532 mmol) and [FeCp2]BF4 (0.009
g, 0.033 mmol) were added to a solution of compound 2 (0.030 g,
0.033 mmol) in dichloromethane (10 mL). The mixture was stirred for
10 min to give a green solution containing compound 5 as the only P-
containing organometallic product. Unfortunately, compound 5 could
not be isolated as a pure material because of its progressive hydrolysis
upon manipulation (to give compounds 3 and 4), and all spectroscopic
data were obtained from these crude reaction mixtures. 1H NMR
(200.13 MHz): δ 7.91−7.32 (m, 25 H, PPh and OPh), 5.83, 5.50 (2s,
2 × 5H, Cp).
Preparation of [W2Cp2(μ-PPh2)2(μ-N:N,N′-N2HC2Me2)(CO)]BF4
(11). Compound 1 (0.030 g, 0.030 mmol) was dissolved in freshly
distilled acetonitrile (10 mL) and stirred for 5 min. The resulting
orange solution was then filtered, petroleum ether (10 mL) was added,
and the solvents were partially removed under vacuum until most of
the product precipitated. The remaining solution was discarded, and
the resulting orange solid was washed with petroleum ether (2 × 10
mL) and dried under vacuum to give compound 11 as an orange solid
(0.029 g, 83%). The crystals used in the X-ray study were grown
through the slow diffusion of a toluene/petroleum ether (1:1) mixture
into a dichloromethane solution of the compound at room
temperature. Anal. Calcd for C39H37BF4N2OP2W2: C, 43.94; H,
3.50; N, 2.63. Found: C, 43.67; H, 3.64; N, 2.37. IR (Nujol): ν(NH)
3347 (w); ν(CO) 1913 (s); ν(CN) 1506 (w); ν(BF) 1050 (s, br). 1H
NMR: δ 12.7 (s, 1H, NH), 7.70−7.10 (m, 16H, Ph), 6.58 (m, 4H, Ph),
6.02, 5.27 (2s, 2 × 5H, Cp), 2.19 (s, 3H, Me), 0.66 (t, 3H, JHP = 5,
Me). 13C{1H} NMR: δ 227.3 (s, WCO), 159.7 (s, WNC), 153.9 (t, JCP
= 8, WNC), 136.7−126.5 (m, Ph), 95.3, 88.1 (2s, Cp), 20.1, 18.0 (2s,
Me).
Preparation of [W2Cp2(μ-H)(Np-tol)(μ-PPh2)2(CO)]BF4 (7).
Solid p-toluidine (0.004 g, 0.037 mmol) was dried by heating under
vacuum and then mixed with a solution of 2 (0.030 g, 0.033 mmol) in
dichloromethane (10 mL). The mixture was stirred for 5 min, and
then solid [FeCp2]BF4 (0.009 g, 0.033 mmol) was added, whereupon
the solution turned orange immediately. The solution was then
filtered, petroleum ether (10 mL) was added, and the solvents were
partially removed under vacuum until most of the product
precipitated. The remaining solution was discarded, and the resulting
orange solid was washed with petroleum ether (2 × 10 mL) and dried
under vacuum to give compound 7 as an orange solid (0.028 g, 78%).
The crystals used in the X-ray study were grown through the slow
diffusion of a diethyl ether/petroleum ether (1:1) mixture into a
dichloromethane solution of the compound at room temperature.
Anal. Calcd for C42H38BF4NOP2W2: C, 46.31; H, 3.52; N, 1.29.
Preparation of [W2Cp2(H)(μ-PPh2)2(μ-CNtBu)(CNtBu)]BF4 (12).
A dichloromethane solution (8 mL) of CNtBu (10 μL, 0.090 mmol)
was placed in a dropping funnel and then added slowly to a solution of
compound 1 (0.030 g, 0.030 mmol) in dichloromethane (10 mL)
cooled at 263 K. The resulting orange solution was further stirred for
10 min, and then diethyl ether (10 mL) was added. The solvents were
partially removed under vacuum until most of the product
precipitated, and the remaining solution was discarded. The resulting
orange solid was washed with diethyl ether (2 × 10 mL) and dried
under vacuum (0.031 g, 91%) to give compound 12 as an essentially
pure orange solid. Attempts to further purify this air-sensitive material
resulted in its progressive decomposition; therefore, no satisfactory
elemental analysis was obtained for this compound. 1H NMR: δ 7.75−
7.17 (m, 20H, Ph), 5.98, 5.15 (2s, 2 × 5H, Cp), 3.64 (s, br, 1H, W−
1
Found: C, 46.13; H, 3.60; N, 1.39. H NMR: δ 7.66 (m, 4H, PPh),
7.48 (m, 4H, PPh), 7.40−7.22 (m, 12H, PPh), 6.82, 6.05 (2 false d, 2
× 2H, JHH = 8, C6H4), 5.85, 5.49 (2s, 2 × 5H, Cp), 2.16 (s, 3H, Me),
−9.18 (t, 1H, JHP = 52, JHW = 34, μ-H). The value of the JHW coupling
of the hydride resonance with the second metal center was estimated
(from the line width of this resonance) to be lower than 9 Hz.
Preparation of [W2Cp2(Np-tol)(μ-PPh2)2(CO)] (8). Neat 1,8-
diazabicycloundec-7-ene (DBU, 25 μL, 0.167 mmol) was added to a
solution of compound 7 (0.020 g, 0.018 mmol) in dichloromethane
(10 mL), and the resulting mixture was stirred for 10 min to give a red
solution. The solvent was then removed under vacuum, and the
residue was chromatographed on alumina (activity IV) at 288 K.
Elution with dichloromethane/petroleum ether (2:1) gave a deep red
fraction yielding, after removal of the solvents, compound 8 as a red
solid (0.017 g, 94%). Anal. Calcd for C42H37NOP2W2: C, 50.38; H,
t
1
H), 1.01, 0.76 (2s, 2 × 9H, Bu). H NMR (400.13 MHz, 213 K): δ
7.76−7.26 (m, 20H, Ph), 6.11, 5.18 (2s, 2 × 5H, Cp), 3.85 (s, 1H, W−
t
H), 0.95, 0.70 (2s, 2 × 9H, Bu). 13C{1H} NMR (100.61 MHz, 213
K): δ 255.1 (s, μ-CNtBu), 199.0 (s, WCNtBu), 144.7, 141.4 [2m,
AXX′, C1(Ph)], 134.1−128.2 (m, Ph), 93.8, 87.1 (2s, Cp), 59.9, 52.6
[2s, C1(tBu)], 30.0, 29.4 [2s, C2(tBu)].
Preparation of [W2Cp2{μ-CN(H)p-tol}(μ-PPh2)2(CNp-tol)(CO)]-
BF4 (13). The procedure and workup was analogous to that described
for 12 but using p-tolylisocyanide (0.011g, 0.093 mmol) and a reaction
temperature of 273 K. This yielded compound 13 as an orange solid
(0.033 g, 90%). In solution, compound 13 was present as an
equilibrium mixture of two isomers 13a and 13b, with their ratio being
solvent-dependent [a/b ratio ca. 2:1 in CD2Cl2 and 5:4 in Me2CO-d6
solution). Anal. Calcd for C51H45BF4N2OP2W2: C, 50.28; H, 3.72; N,
2.30. Found: C, 49.87; H, 3.44; N, 2.11. IR (Nujol): ν(NH) 3311 (w),
ν(CN) 2110 (vs), ν(CO) 1949 (s), ν(BF) 1055 (vs, br).
1
3.72; N, 1.40. Found: C, 50.73; H, 3.87; N, 1.45. H NMR (200.13
MHz): δ 7.85 (m, 4H, PPh), 7.31−7.18 (m, 12H, PPh), 6.89 (m, 4H,
PPh), 6.48, 5.64 (2 false d, 2 × 2H, JHH = 8, C6H4), 5.23, 5.14 (2s, 2 ×
5H, Cp), 1.90 (s, 3H, Me).
Preparation of [W2Cp2(H)(μ-PPh2)2(CO)(PH2Cy)]BF4 (9). Cyclo-
hexylphosphine (18 μL, 0.14 mmol) was added to a solution of
compound 1 (0.070 g, 0.071 mmol) in dichloromethane (10 mL), and
the mixture was stirred for 4 h to give a green solution containing
compound 9 and small amounts of 4. The solution was then filtered,
and the solvent was removed from the filtrate. Recrystallization of this
crude product from dichloromethane/petroleum ether gave green
crystals of 9, which were washed with petroleum ether and dried under
1
Spectroscopic data for 13a: H NMR (200.13 MHz): δ 9.37 (s, br,
1H, NH), 7.62 (m, 4H, Ph), 7.37−7.22 (m, 12H, Ph), 6.91 (m, 4H,
Ph), 5.89, 5.51 (2m, 2 × 2H, C6H4), 5.72, 5.23 (2s, 2 × 5H, Cp), 2.28,
2.24 (2s, 2 × 3H, Me). 13C{1H} NMR (100.61 MHz, Me2CO-d6): δ
J
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
315.7 (t, JPC = 41, μ-CN), 230.2 (t, JPC = 7, WCO), 168.1 (t, JPC = 8,
WCN), 143.9−126.3 (m, Ph and C6H4), 90.3, 89.5 (2s, Cp), 21.1, 20.9
(2s, Me). Spectroscopic data for 13b: 1H NMR (200.13 MHz): δ 9.37
(s, br, 1H, NH), 7.62 (m, 4H, Ph), 7.37−7.22 (m, 12H, Ph), 6.91 (m,
4H, Ph), 5.96, 5.53 (2m, 2 × 2H, C6H4), 5.68, 5.17 (2s, 2 × 5H, Cp),
2.28, 2.25 (2s, 2 × 3H, Me). 13C{1H} NMR (100.61 MHz, Me2CO-
d6): δ 312.6 (t, JPC = 41, μ-CN), 226.2 (t, JPC = 7, WCO), 164.3 (t, JPC
= 8, WCN), 143.9−126.3 (m, Ph and C6H4), 90.6, 88.9 (2s, Cp), 21.1,
20.9 (2s, Me).
Computational Details. The computations for compounds 2 and
2+ were carried out using the GAUSSIAN03 package,42 in which the
hybrid methods B3LYP (2) and UB3LYP (2+) were applied with the
Becke three parameters exchange functional43 and the Lee−Yang−
Parr correlation functional.44 An accurate numerical integration grid
(99,590) was used for all calculations via the keyword Int=Ultrafine.
Effective core potentials (ECP) and their associated double-ζ
LANL2DZ basis set were used for the metal atoms.45 The light
elements (P, O, C, and H) were described with the 6-31G* basis set.46
Geometry optimizations were performed under no symmetry
restrictions, using initial coordinates derived from the X-ray data of
the Mo analogue of 2, and frequency analysis was performed to ensure
that a minimum structure with no imaginary frequencies was achieved
in each case. Molecular orbitals and vibrational modes were visualized
using the MOLEKEL program.47 The topological analysis of the
electron density was carried out with the Xaim routine.48
X-ray Structure Determination of Compound 7. The
diffraction data for this compound were collected at 293 K on a
Siemens AED single-crystal diffractometer, using Mo Kα graphite
monochromated radiation (λ = 0.71073 Å). The structure was solved
by direct methods with SHELXS-9749 and refined against F2 with
SHELXL-97,50 with anisotropic thermal parameters for all non
hydrogen atoms. The hydrogen atoms were placed in the ideal
geometrical positions. The hydride H1 atom was found in the ΔF
map. Details of the X-ray diffraction collection are reported in Table
S8 in Supporting Information.
Robert, F. Organometallics 2002, 21, 1177. (b) Alvarez, M. A.; García,
M. E.; Riera, V.; Ruiz, M. A. Organometallics 1999, 18, 634. (c) Alvarez,
M. A.; Bois, C.; García, M. E.; Riera, V.; Ruiz, M. A. Angew. Chem., Int.
Ed. Engl. 1996, 35, 102.
(3) (a) García, M. E.; Melon
2009, 8171. (b) García, M. E.; Melon
M. A.; Belletti, D.; Graiff, C.; Tiripicchio, A. Organometallics 2003, 22,
1983. (c) Alvarez, M. A.; García, M. E.; García-Vivo, D.; Ruiz, M. A.;
Vega, M. F. Organometallics 2010, 29, 512.
(4) (a) García, M. E.; García-Vivo, D.; Ruiz, M. A.; Alvarez, S.;
Aullon, G. Organometallics 2007, 26, 4930. (b) Alvarez, C. M.; Alvarez,
M. A.; García, M. E.; García-Vivo, D.; Ruiz, M. A. Organometallics
2005, 24, 4122.
(5) Alvarez, M. A.; García, M. E.; Martínez, M. E.; Menen
Ruiz, M. A. Organometallics 2010, 29, 710.
(6) (a) García, M. E.; García-Vivo, D.; Ruiz, M. A.; Herson, P.
Organometallics 2008, 27, 3879. (b) García, M. E.; García-Vivo, D.;
Ruiz, M. A. Organometallics 2008, 27, 543.
(7) (a) García, M. E.; García-Vivo, D.; Ruiz, M. A. Organometallics
2010, 29, 2157. (b) García, M. E.; García-Vivo, D.; Ruiz, M. A.
Organometallics 2009, 28, 4385. (c) García, M. E.; García-Vivo, D.;
Ruiz, M. A. Organometallics 2008, 27, 169. (d) García, M. E.; García-
Vivo, D.; Ruiz, M. A.; Aullon, G.; Alvarez, S. Organometallics 2007, 26,
5912.
(8) Alvarez, M. A.; García, M. E.; Martínez, M. E.; Ramos, A.; Ruiz,
M. A.; Saez, D. Inorg. Chem. 2006, 45, 6965.
́
, S.; Ramos, A.; Ruiz, M. A. Dalton Trans.
́
, S.; Ramos, A.; Riera, V.; Ruiz,
́
́
́
́
́
dez, S.;
́
́
́
́
́
́
́
́
(9) (a) Maitlis, P. M.; Zanotti, V. Chem. Commun. 2009, 1619.
(b) Maitlis, P. M. J. Organomet. Chem. 2004, 689, 4366. (c) Maitlis, P.
M. J. Mol. Catal. A 2003, 204 (205), 55. (d) Dry, M. E. Catal. Today
2002, 71, 227.
(10) Alvarez, M. A.; García, M. E.; García-Vivo,
Ruiz, M. A. Organometallics 2013, 32, 218.
(11) Cimadevilla, F.; García, M. E.; García-Vivo,
́
D.; Menen
́
dez, S.;
́
D.; Ruiz, M. A.;
Graiff, C.; Tiripicchio, A. Inorg. Chem. 2012, 51, 10427.
(12) Jameson, C. J. In Phosphorus-31 NMR Spectroscopy in
Stereochemical Analysis; Verkade, J. G., Quin, L. D., Eds.; VCH:
Deerfield Beach, FL, 1987; Chapter 6.
(13) Curtis, M. D.; Hay, M. S.; Butler, W. M.; Kampf, J.; Rheingold,
A. L.; Haggerty, B. S. Organometallics 1992, 11, 2884.
ASSOCIATED CONTENT
* Supporting Information
■
S
CIF file giving the crystallographic data for the structural
analysis of compound 7; PDF file containing data (complete ref
42, figures, selected bond distances and angles, selected
molecular orbitals, atomic charges and topological properties
of the electron density) for the DFT-optimized structures of 2
and 2+, and a table with crystal data of compound 7. This
material is available free of charge via the Internet at http://
pubs.acs.org.
(14) Gom
́
ez Sal, P.; Jimen
́
ez, I.; Martín, A.; Pedraz, T.; Royo, P.;
Selles, A.; Vaz
́
́
quez de Miguel, A. Inorg. Chim. Acta 1998, 273, 270.
(15) Li, L.; White, P. S.; Brookhart, M.; Templeton, J. L. J. Am. Chem.
Soc. 1990, 112, 8190.
(16) Danopoulos, A. A.; Redshaw, C.; Vaniche, A.; Wilkinson, G.;
Hussain-Bates, B.; Hursthouse, M. B. Polyhedron 1993, 12, 1061.
(17) Pet
Coord. Chem. Rev. 1998, 178−180, 203.
(18) Cimadevilla, F.; García, M. E.; García-Vivo,
Graiff, C.; Tiripicchio, A. Inorg. Chem. 2012, 51, 7284.
(19) Wrackmeyer, B.; Alt, H. G.; Maisel, H. E. J. Organomet. Chem.
1990, 399, 125.
́
illon, F. Y.; Schollhammer, P.; Talarmin, J.; Muir, K. W.
́
D.; Ruiz, M. A.;
AUTHOR INFORMATION
Corresponding Author
*E-mail: mara@uniovi.es.
■
(20) García, M. E.; Riera, V.; Ruiz, M. A.; Rueda, M. T.; Sae
́
z, D.
Notes
Organometallics 2002, 21, 5515.
The authors declare no competing financial interest.
(21) (a) Koch, W.; Holthausen, M. C. A Chemist’s Guide to Density
Functional Theory, 2nd ed.; Wiley-VCH: Weinheim, Germany, 2002.
(b) Ziegler, T. Chem. Rev. 1991, 91, 651. (c) Foresman, J. B.; Frisch,
Æ. Exploring Chemistry with Electronic Structure Methods, 2nd ed.;
Gaussian, Inc.: Pittsburg, 1996.
ACKNOWLEDGMENTS
■
We thank the DGI of Spain (Projects CTQ2009-09444 and
CTQ2012-33187) and the European Commission (Project
PERG08-GA-2010-276958) for supporting this work and the
(22) Bader, R. F. W. Atoms in Molecules−A Quantum Theory; Oxford
University Press: Oxford, U.K., 1990.
́
́
Consejeria de Educacion of Asturias for a “Clarin” postdoctoral
́
(23) Kukushkin, V. Y.; Pombeiro, A. J. L. Chem. Rev. 2002, 102, 1771.
(24) (a) Ma, M.; Stasch, A.; Jones, C. Chem.Eur. J. 2012, 18,
reintegration grant (D.G.V.).
10669. (b) Lopez, L. P. H.; Schrock, R. R.; Muller, P. Organometallics
̈
REFERENCES
2008, 27, 3857. (c) Cross, J. L.; Garrett, A. D.; Crane, T. W.; White, P.
S.; Templeton, J. L. Polyhedron 2004, 23, 2831. (d) Tsai, Y. C.;
Stephens, F. H.; Meyer, K.; Mendiratta, A.; Gherorghiu, M. D.;
Cummins, C. C. Organometallics 2003, 22, 2902. (e) Young, C. G.;
Philipp, C. C.; White, P. S.; Templeton, J. L. Inorg. Chem. 1995, 34,
6412. (f) Barry, J. T.; Chacon, S. T.; Chisholm, M. H.; Huffman, J. C.;
■
(1) García, M. E.; Riera, V.; Rueda, M. T.; Ruiz, M. A.; Halut, S. J.
Am. Chem. Soc. 1999, 121, 1960.
(2) The first thermally stable hydroxycarbyne complex reported was
the 32-electron species [W2Cp2(μ-COH)(μ-Ph2PCH2PPh2)(CO)2]
BF4; see: (a) Alvarez, M. A.; García, M. E.; Riera, V.; Ruiz, M. A.;
K
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Streib, W. E. J. Am. Chem. Soc. 1995, 117, 1974. (g) Cotton, F. A.;
Hall, W. T. J. Am. Chem. Soc. 1979, 101, 5094. (h) Duchateau, R.;
Williams, A. J.; Gambarotta, S.; Chiang, M. Y. Inorg. Chem. 1991, 30,
4863. (i) Esjornson, D.; Derringer, D. R.; Fanwick, P. E.; Walton, R. A.
Inorg. Chem. 1989, 28, 2821. (j) De Boer, E. J. M.; Teuben, J. H. J.
Organomet. Chem. 1978, 153, 53. (k) Cotton, F. A.; Hall, W. T. Inorg.
Chem. 1978, 17, 3525. (l) Finn, P. A.; King, M. S.; Kilty, P. A.;
McCarley, R. E. J. Am. Chem. Soc. 1975, 97, 220.
(47) Portmann, S.; Luthi, H. P. MOLEKEL: An Interactive
̈
Molecular Graphics Tool. CHIMIA 2000, 54, 766.
́
́
(48) Ortiz, J. C.; Bo, C. Xaim; Departamento de Quımica Fısica e
Inorganica, Universidad Rovira i Virgili: Tarragona, Spain, 1998.
́
(49) Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467.
(50) Sheldrick, G. M. Acta Crystallogr. 2008, A64, 112.
(25) Crystal data for compound 11: formula = C39H17BF4N2OP2W2,
molecular weight 1046.00, monoclinic, space group = P21/n, a =
14.724(4) Å, b = 17.519(6) Å, c = 15.276(5) Å, β = 104.57(5)°, V =
3814(2) Å3, Z = 4.
(26) (a) Alvarez, M. A.; García, M. E.; García-Vivo,
Ruiz, M. A. Inorg. Chem. 2011, 50, 2064. (b) Alvarez, M. A.; García, M.
E.; García-Vivo, D.; Ramos, A.; Ruiz, M. A. Inorg. Chem. 2012, 51,
11061.
́
D.; Ramos, A.;
́
(27) (a) Riera, V.; Ruiz, M. A.; Villafane, F.; Bois, C.; Jeannin, Y.
̃
Organometallics 1993, 12, 124. (b) Alvarez, M. A.; García, M. E.;
Ramos, A.; Ruiz, M. A. Organometallics 2007, 26, 1461. (c) Alvarez, M.
A.; García, M. E.; Ramos, A.; Ruiz, M. A.; Lanfranchi, M.; Tiripicchio,
A. Organometallics 2007, 26, 5454. (d) García, M. E.; García-Vivo,
Ruiz, M. A. J. Organomet. Chem. 2010, 695, 1592. (e) Alvarez, M. A.;
García, M. E.; Menendez, S.; Ruiz, M. A. Organometallics 2011, 30,
3694.
́
D.;
́
(28) Carty, A. J.; MacLaughlin, S. A.; Nucciarone, D. In Phosphorus-
31 NMR Spectroscopy in Stereochemical Analysis; Verkade, J. G., Quin,
L. D., Eds.; VCH: Deerfield Beach, FL, 1987; Chapter 16.
(29) Alvarez, M. A.; Anaya, Y.; García, M. E.; Riera, V.; Ruiz, M. A.
Organometallics 2004, 23, 433.
(30) Yamamoto, Y. Coord. Chem. Rev. 1980, 32, 193.
(31) Yamamoto, Y.; Yamazaki, H. Inorg. Chem. 1986, 25, 3327.
(32) Fukushima, T.; Kobayashi, K.; Nomura, T.; Tanase, T.;
Yamamoto, Y. Inorg. Chem. 1994, 33, 32.
(33) Fukushima, T.; Kobayashi, K.; Nomura, T.; Tanase, T.;
Yamamoto, Y. Inorg. Chem. 1993, 32, 4578.
(34) Martins, A. M.; Calhorda, M. J.; Romao, C. C.; Volk, C.; Kiprof,
̈
P.; Filippou, A. C. J. Organomet. Chem. 1992, 423, 367.
(35) Filippou, A. C.; Grunleitner, W.; Volk, C.; Kiprof, P. Angew.
̈
̈
Chem., Int. Ed. Engl. 1991, 30, 1167.
(36) Alt, H. G.; Frister, T. J. Organomet. Chem. 1985, 293, C7.
(37) Alvarez, M. A.; García, M. E.; Ruiz, M. A.; Vega, M. F. Dalton
Trans. 2011, 40, 8294.
(38) (a) Fujita, K.; Nakaguma, H.; Hanasaka, F.; Yamaguchi, R.
Organometallics 2002, 21, 3749. (b) Werner, H.; Zolk, R.; Hofmann,
W. J. Organomet. Chem. 1986, 302, 65. (c) Fischer, H.; Hoffmann, P.;
Kreissl, F. R.; Schrock, R. R.; Schubert, U.; Weiss, K. Carbyne
Complexes; VCH: Weinheim, Germany, 1988. (d) Pombeiro, A. J. L.;
Guedes da Silva, M. F. C.; Michelin, R. A. Coord. Chem. Rev. 2001,
218, 43. (e) Adams, R. D.; Babin, J. E.; Kim, H. S. Polyhedron 1988, 7,
967.
(39) (a) Adams, R. D.; Golembesky, N. M. J. Am. Chem. Soc. 1979,
101, 2579. (b) Prest, D. W.; Mays, M. J.; Raithby, P. R. J. Chem. Soc.,
Dalton Trans. 1982, 2021. (c) García-Alonso, F. J.; García-Sanz, M.;
Riera, V.; Anillo-Abril, A.; Tiripicchio, A.; Ugozzoli, F. Organometallics
1992, 11, 801. (d) Cabon, N.; Petillon, F. Y.; Schollhammer, P.;
́
Talarmin, J.; Muir, K. W. Dalton Trans. 2004, 2708.
(40) Armarego, W. L. F.; Chai, C. Purification of Laboratory
Chemicals;, 5th ed.; Butterworth-Heinemann: Oxford, U.K., 2003.
(41) Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 877.
(42) Frisch, M. J. et al. Gaussian 03, Revision B.02; Gaussian, Inc.:
Wallingford, CT, 2004.
(43) Becke, A. D. J. Chem. Phys. 1993, 98, 5648.
(44) Lee, C.; Yang, W.; Parr, R. G. Phys. Rev. B 1988, 37, 785.
(45) Hay, P. J.; Wadt, W. R. J. Chem. Phys. 1985, 82, 299.
(46) (a) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28,
213. (b) Petersson, G. A.; Al-Laham, M. A. J. Chem. Phys. 1991, 94,
6081. (c) Petersson, G. A.; Bennett, A.; Tensfeldt, T. G.; Al-Laham, M.
A.; Shirley, W. A.; Mantzaris, J. J. Chem. Phys. 1988, 89, 2193.
L
dx.doi.org/10.1021/om400598m | Organometallics XXXX, XXX, XXX−XXX