Coordination behavior of the S-C-S monoanion and O-C-O and S-C-S dianions toward CoII

Article abstract of DOI:10.1002/ejic.201100144

The reactivity of both the monoanionic and dianionic forms of bis(diphenylthiophosphinoyl)methane (2^- and 2^2-) as well as the dianion of tetraisopropyl methylenediphosphonate(3^2-) was investigated towards the same Co^I

Full text of DOI:10.1002/ejic.201100144

FULL PAPER
DOI: 10.1002/ejic.201100144
Coordination Behavior of the S–C–S Monoanion and O–C–O and S–C–S
Dianions toward CoII
Hadrien Heuclin,[a] Thibault Cantat,[a][‡] Xavier Frédéric Le Goff,[a] Pascal Le Floch,[a][†] and
Nicolas Mezailles*[a]
Keywords: Cobalt / Anions / Pincer ligands / Density functional calculations
The reactivity of both the monoanionic and dianionic forms
of bis(diphenylthiophosphinoyl)methane (2– and 22–) as well
as the dianion of tetraisopropyl methylenediphosphonate
(32–) was investigated towards the same CoII precursor
CoCl2. Monoanion 2– coordination yields a homoleptic zwit-
give the same overall structure with a square Co2C2 core.
Structures of all of the complexes have been confirmed by
full NMR spectroscopic analysis and X-ray diffraction.
Furthermore, DFT calculations have been carried out to ratio-
nalize the stability of such species.
terionic CoII complex. However, both dianions (22– and 32–
)
been shown to be excellent precursors to transition-metal
carbenes[5] as well as group 2,[6] rare earth,[7] and uranium[8]
Introduction
The coordination chemistry of the monoanions and di- carbene complexes. One of the strategies (“route I”,
anions of bis(iminophosphorane), 1–[1] and 12–,[2] respec- Scheme 1) toward the synthesis of such carbene complexes
tively, and of the dianion of bis(thiophosphinoyl)methane, relies on a two-step sequence: coordination of monoanion
22–,[3] has been studied in depth (Scheme 1), especially in A– followed by deprotonation of the ligand in the coordina-
the past decade.[4] In particular, dianions 12– and 22– have tion sphere of the metal. In the very large majority of the
Scheme 1. Routes toward the synthesis of carbene complexes.
[a] Laboratoire “Hétéroéléments et Coordination”, UMR CNRS
cases, the intermediate structure C is obtained rather than
7653 (DCPH), Département de Chimie, Ecole Polytechnique,
structure B from the coordination of the monoanion to
metal centers. This “route I” has been most extensively
studied with the bis(iminophosphorane) ligands, 1. On the
other hand, the synthesis of transition-metal carbene com-
plexes with ligand 2 almost only relied on the use of the
geminal dianion, 22–, as precursor (“route II”, Scheme 1).
By choosing either “route I” or “route II”, the typical out-
91128 Palaiseau Cedex, France
Fax: +33-1-69334440
E-mail: nicolas.mezailles@polytechnique.fr
[‡] Current address: CEA Saclay, DSM/IRAMIS/SIS2M, Bâtiment
125,
91191 Gif-sur-Yvette, France
[†] Deceased on March 17, 2010
Supporting information for this article is available on the
WWW under http://dx.doi.org/10.1002/ejic.201100144.
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Eur. J. Inorg. Chem. 2011, 2540–2546

Coordination Behavior of O–C–O and S–C–S Anions
Scheme 2. Examples of group 9 metal complexes synthesized using routes I and II (cod = cycloocta-1,5-diene; coe = cyclooctene).
come of the reactions is the formation of the carbene com- cies, which was therefore postulated to be complex 4. After
plex (structure D) rather than dinuclear complex E. Notable evaporation of THF, dissolution of the complex in dichloro-
examples of the “nontypical” cases are found mostly for methane, and filtration to remove LiCl, complex 4 was ob-
group 9 complexes. Indeed, reactions of 1– with either RhI tained in good yield after evaporation of the solvent (80%;
or IrI precursors leads to a complex of type B (Scheme 2),[9] Scheme 3).
and reaction of 12– with one equivalent of RhI precursor
resulted in the formation of a mixed Rh–Li complex. This
complex could then be reacted with another equivalent of
metal precursor to generate bimetallic complexes, in which
the dianion acts as a bridging moiety, reminiscent of struc-
ture E.[10] We have recently reported that the reaction of 2–
with one equivalent of IrI precursor led to the formation of
an IrIII complex resulting from the CH insertion in one
Scheme 3. Synthesis of complex 4.
phenyl substituent of the ligand.[11] Finally, the reaction of
two different ligands of type 1– (R = C6H2Me3 and
Surprisingly, the 31P NMR spectrum of 4 in dichloro-
C6H3iPr2) with CoCl2 is reported to form a complex of the
methane showed a broad singlet at δ = +4 ppm, but when
type [(1)CoCl], yet their structures (B or C) are not
the complex was redissolved in THF after evaporation of
known.[12]
dichloromethane, the 31P NMR spectrum showed the broad
These peculiar results prompted us to study the coordi-
singlet at δ = +70 ppm. This points to a very large influence
nation behavior of both the anions and dianions of 2 and
of the solvent on the chemical shift of 4. Indeed, we found
3 toward a CoII precursor. We show here that coordination
that this chemical shift depends on the ratio of the CH2Cl2/
of 2– leads to the formation of a complex that lacks Co–C
THF mixture, ranging from +4 ppm (100% dichlorometh-
bonding unlike the complexes of the heavier elements (RhI
ane) to +70 ppm (100% THF). Such solvent effects on CoII
and IrI). The reactivity of dianions 22– and 32–, on the other
complexes have already been reported in the literature.[14]
hand, is shown to follow a path similar to the Rh analogue,
Complex 4 was further characterized by multinuclear NMR
leading to the dinuclear bridging species.
1
spectroscopy in CD2Cl2. The H NMR spectrum exhibits
only very broad signals for the various protons of the
phenyl substituents, yet in the diamagnetic range (δ = 6.2
Results and Discussion
to 8.7 ppm), which suggests a moderate influence of the
In the first stage, monoanion 2– was synthesized by paramagnetic CoII center on these chemical shifts. Neither
1
addition of methyllithium (1 equiv.) to 1,1-bis(diphenyl- the signal for the proton of the PC(H)P bridge (in the H
thiophosphinoyl)methane (DPPMS2) in toluene, diethyl spectrum) nor the signal of the corresponding carbon (in
ether, or THF.[13] The 1:1 stoichiometric reaction between the 13C spectrum) was observed. To gain more information
the ligand and CoCl2, at room temperature in THF for on the bonding between the ligand and the metal center, a
12 h, led to the formation of a green complex. This complex variable-temperature 31P NMR spectroscopic experiment
was characterized by a broad singlet in the 31P{1H} spec- was carried out. Lowering the temperature to –80 °C and
trum at δ = +70 ppm, shifted downfield by approximately warming back to 0 °C in CD2Cl2 did not show any change
33 ppm from the monoanion. The reaction performed with in the shape or intensity of the signal. However, the chemi-
2:1 stoichiometry resulted in the formation of the same spe- cal shift was strongly affected, as chemical shifts were ob-
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H. Heuclin, T. Cantat, X. F. Le Goff, P. Le Floch, N. Mezailles
FULL PAPER
served between δ = –68 and +4 ppm. Variations of the ionic species consisting of a central Co2+ and two anionic
chemical shift of the phosphorus atoms relative to the tem- ligands 2–, which behave as bidentate ligands through the
perature are shown in Table 1.
two S atoms and not as pincer anionic SCS ligands. This
bonding of the monoanion with the d7 CoII center is there-
fore very different from that observed for analogous
monoanionic ligands with d8 RhI and IrI centers.
Table 1. Variation of the 31P chemical shift of 4 with temperature
(in CD2Cl2).
T [°C]
δP [ppm]
T [°C]
–80
–68
–30
–16
–70
–54
–20
–11
–60
–43
–10
–7
–50
–31
0
–40
–22
20
The absence of C bonding between the monoanionic li-
gand 2– and the metal prompted us to study the reactivity
of dianion 22– with the same cobalt precursor. Indeed, in
all the cases studied so far, the dianion appeared as a very
strong ligand, with the C atom always bound to either one
or two metal centers (structures D or E, Scheme 1). Reac-
tion of one equivalent of dianion 22– with one equivalent
of CoCl2 was therefore carried out in toluene at room tem-
perature, and followed by 31P NMR spectroscopy
(Scheme 4). After 12 h of stirring, the spectrum showed the
complete formation of a new complex. After filtration and
evaporation of the solvent, complex 5 was isolated as a
brown solid in 75% yield. It was fully characterized by mul-
tinuclear NMR spectroscopy.
δP [ppm]
–3
+4
This phenomenon is indicative of ligand coordination to
a paramagnetic center, and not of a dynamic process involv-
ing an equilibrium between a coordinated and uncoordi-
nated C center to the Co atom.[15] It is interesting to note
that complex 4 does not react with dichloromethane, unlike
ligand 2–, which points to a strong C–Co interaction in the
complex. At this point, no definitive answer regarding the
presence or lack of Co–C could be drawn. Single crystals
were grown from a concentrated solution of 4 in toluene at
room temperature, and the solid-state structure of the com-
plex was then obtained by X-ray diffraction analysis. A view
of complex 4 is given in Figure 1, clearly showing that the
two central carbon atoms of the monoanion are not coordi-
nated to the cobalt center in the solid state. The Co–C dis-
tances [Co1–C1 3.230 Å, Co1–C2 3.824 Å] are far longer
than the typical Co–C distances reported in the literature
for pincer complexes.[16] The geometry at the Co center is
distorted tetrahedral, as shown by the very different angles
of S–Co–S [between 93.21(4) and 123.46(4)°]. Also, the P–
C bond lengths within the ligand are similar to those found
in monoanion 2–[13] [1.711 Å (av.) in 2– vs. 1.706 Å (av.) in
4 for P–C bonds], which shows that the stabilization of the
charge at C is similar in both species. Thus, it appears that
the stabilization of the lone pair at C by the two substitu-
ents PPh2S is strong enough, and does not require further
C–Co bonding interaction. Thus, complex 4 is a zwitter-
Scheme 4. Synthesis of complex 5.
Complex 5 exhibits a low-field signal at δ = +187 ppm in
the 31P NMR spectrum. This is a much higher chemical
shift than what is usually observed for this ligand, which
confirms the formation of a paramagnetic complex. The 1H
NMR spectrum presents signals ranging from δ = –9 to
+13 ppm for the phenyl hydrogen atoms, which are much
more influenced by the paramagnetic CoII center than those
in complex 4. In the 13C NMR spectrum, no signal could
be observed for the carbon of the PCP bridge nor for the
ones associated with the protons at δ = –9 ppm (in the ortho
1
position on the phenyl rings) in the H NMR spectra. The
precise structure of complex 5 could not be deduced from
the NMR spectroscopic data but was obtained by X-ray
crystal structure analysis. Crystals were obtained by slow
diffusion of hexanes into a concentrated solution of 5 in
dichloromethane. A view of complex 5 is shown in Figure 2.
Complex 5 features a planar Co–C–Co–C metallacycle
(structure E, Scheme 1), with each ligand binding the two
cobalt atoms. The Co–C distances [Co1–C1 2.044(3) Å,
Co1–C1Ј 2.044(3) Å] are in the normal range of Co–C
bonds observed in other complexes.[16] The P–S bonds in 5
are only slightly shorter than in dianion 22– (2.022 Å in
average in 5 vs. 2.040 Å in 22–), whereas the P–C bonds are
significantly longer than in 22– (av. 1.735 Å vs. av.
1.676 Å).[3] This latter point is directly correlated to the
strength of the donation of the lone pairs at C to the metal
Figure 1. Molecular view of complex 4. Thermal ellipsoids are
drawn at the 50% probability level. Hydrogen atoms on the phenyl
rings and solvent molecules have been omitted for clarity. Selected
bond lengths [Å] and angles [°]: Co–S1 2.327(1), Co–S2 2.331(1),
Co–S3 2.308(1), Co–S4 2.357(1), C1–P1 1.701(4), C1–P2 1.715(3),
P1–S1 2.032(1), P2–S2 2.025(1), C2–P3 1.703(3), C2–P4 1.706(3),
P3–S3 2.045(1), P4–S4 2.015(1); P1–C1–P2 125.3(2), P3–C2–P4
124.1(2), S3–Co–S1 105.08(4), S3–Co–S2 123.46(4), S3–Co–S4
110.29(3), S2–Co–S4 93.21(4).
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Coordination Behavior of O–C–O and S–C–S Anions
center(s) versus their stabilization by hyperconjugation into
low-lying σ* orbitals at the P substituent (P–Ph and P–S).
These facts point to a relatively strong C–Co interaction.
The Co–Co distance of 2.4710(7) Å suggests a bonding in-
teraction between the two cobalt atoms (a search of the
CCDC database for all complexes containing any type of
Co–Co bond gave a distribution of the Co–Co distances
centered on 2.5 Å). This Co–Co interaction has been
studied by DFT calculations and the results are presented
Scheme 5. Synthesis of complex 6.
1
below. The evolution of the 31P and H NMR spectra was
studied with respect to the temperature in CD2Cl2. Note
that here again, no reaction was observed between 5 and
dichloromethane. The results are shown in Table 2.
either the complex being a diamagnetic species, or a para-
magnetic complex with a weaker influence of the CoII cen-
ter on the ligand. A variable-temperature experiment was
carried out, and the 31P chemical shift did not evolve with
1
temperature. The H and 13C NMR spectra were quite un-
informative, except for the chemical shift of the proton of
the iPr substituent, which was observed at very low field (δ
= 6.4 ppm). The structure of the complex was elucidated by
X-ray diffraction analysis. Single crystals of complex 6 were
obtained by slow diffusion of hexanes into a concentrated
solution of 6 in THF. A view of complex 6 is shown in
Figure 3. The central core of the structure of complex 6 is
similar to that of complex 5. Both feature a C2Co2 square
core. However, in 6 the oxygen atoms of the P=O arms are
not coordinated to the metal, which suggests that Cl– is a
better ligand than P=O. The stabilization of the complex is
assisted by the presence of 4 lithium atoms. The P=O bonds
in 6 are longer than in the neutral ligand[19] 3 [1.508(3) and
1.512(3) Å in 6 vs. 1.4840(12) and 1.4756(13) Å in 3],
whereas the two P–C bonds are significantly shorter
Figure 2. Molecular view of complex 5. Thermal ellipsoids are
drawn at the 50% probability level. Hydrogen atoms have been
omitted for clarity. Selected bond lengths [Å] and angles [°]: Co1–
Co2 2.4710(7), Co1–C1 2.044(3), Co2–C1 2.044(3), Co1–S1
2.3408(8), Co2–S2 2.3627(8), C1–P1 1.728(3), C1–P2 1.742(3), P1–
S1 2.024(1), P2–S2 2.021(1); P1–C1–P2 129.7(1), C1–Co2–C1Ј
105.6(2), C1–Co2–S2 84.20(8), Co1–C1–C1Ј–Co2 0.00.
[1.713(1) and 1.714(3) Å in
6
vs. 1.7924(17) and
1.7950(18) Å in 3]. This indicates that the electron density
initially on the C atom of the dianion is strongly stabilized
by the substituents at P, rather than efficiently transferred
to the metal centers. On the other hand, in complex 5 the
P–C bonds are 1.728(3) and 1.742(3) Å, which clearly indi-
cates a more efficient electron transfer from the carbon to
the metals.
Table 2. Evolution of the 1H and 31P chemical shifts of 5 with tem-
perature in CD2Cl2.
T [°C]
δP [ppm]
δortho-H [ppm]
–80
147
–70
150
–15
–60
154
–50
158
–40
161
–13
25
187
–9
We had previously shown that dianions 22– and 32– re-
acted very differently towards ZrIV. Indeed, when the bis-
(thiophosphinoyl) ligand led to a monocarbene complex,[17]
the bis(phosphonate) led to a triscarbene complex.[18] This
prompted us to study the reactivity of 32– with the same
CoII precursor. Ligand 32– is insoluble in the solvents in
which it does not react (toluene, Et2O). In toluene, in which
CoCl2 is also insoluble, no reaction was seen even after
three days. However, heating the suspension at 80 °C for
3 h allowed the formation of a novel species, as a purple
precipitate, that was readily isolated by filtration
(Scheme 5). Interestingly, no precipitation of the LiCl salt
was observed during this reaction.
Figure 3. Molecular view of complex 6. Thermal ellipsoids are
drawn at the 50% probability level. Hydrogen atoms, isopropyl
groups, and carbon atoms of the THF molecules have been omitted
for clarity. Selected bond lengths [Å] and angles [°]: Co1–Co1Ј
2.724(1), Co1–C1 2.077(3), Co1Ј–C1 2.092(3), Co1–Cl1 2.353(1),
Co1–Cl2 2.346(1), C1–P1 1.713(1), C1–P2 1.714(3), P1–O1
1.508(3), P2–O2 1.512(3); P1–C1–P2 123.4(2), C1–Co1Ј–C1Ј
Once formed, the complex was soluble in THF, which
allowed a full characterization. The 31P NMR spectrum of
this complex showed a singlet at δ = +63 ppm, thus proving
the conversion of the starting material into a single new
species. Interestingly, this chemical shift is consistent with 98.4(1), Co1–C1–C1Ј–Co1Ј 0.0.
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H. Heuclin, T. Cantat, X. F. Le Goff, P. Le Floch, N. Mezailles
FULL PAPER
The Co–Co distance of 2.724(1) Å in 6 is longer than possesses a pure metal character as it does not have the
that in 5 [2.4710(7) Å] as are the Co–C distances [Co–C right symmetry to overlap with orbitals at the ligands. On
2.077(3) and 2.092(3) Å in 6 vs. Co–C 2.044(3) and the other hand, the SOMO (Figure 4, right) is not a “pure
2.044(3) Å in 5], which also indicate a weaker interaction d” metal orbital, and presents an antibonding interaction
(Scheme 6). To obtain further insights in the bonding of the of the Co centers with the ligands. This orbital therefore
dinuclear complexes, DFT calculations were performed on results from the overlap of the positive interaction of the
complex 5 using the Gaussian03 set of programs.[20] The two dx2–y2 orbitals at the Co centers, in an antibonding fash-
PBEPBE[21] functional was used in combination with the 6- ion with two lone pairs at C (Scheme 7). This explains why
31++G** for the core carbon atoms, 6-31+G* for the these orbitals lie close in energy, thereby favoring the triplet
metal-bound atoms (P, S), 6-31G* for the ipso-carbon state. In the optimized geometry of the singlet-state species,
atoms, and 3-21G* for the remaining atoms (C, H of the the Co–Co bond length is calculated at 2.54 Å, much longer
phenyl groups). DZVP2[22] was used for the cobalt (details than that in the triplet-state complex (2.42 Å). This is fully
on the optimized structures are given in the electronic Sup- consistent with the transfer of an electron from the SOMO
porting Information). Two spin states have been considered into the SOMO–1, increasing the antibonding interaction
for this species, a singlet and a triplet (5s, 5t). Both geome- between the two Co centers.
tries have been optimized as minima on the potential-en-
ergy surface (PES) and the triplet turns out to be more
stable by approximately 8 kcalmol–1 (G), in agreement with
the experimental findings. A comparison of the structural
parameters of the calculated structure and the experimental
data is shown in Table 3. All calculated distances are in
good agreement with the experimental data except for the
Co–C distances that were found to be shorter, corroborated
by the overestimation of the P–C bonds. Attempts to obtain
more satisfying results were made by changing the basis sets
(def2-qzvp, dzvp2) on C1 and C2 and the functional (b3ylp,
opbe), but were not successful.
Figure 4. SOMO–1 (left) and SOMO (right) of complex 5.
Scheme 7. Correlation diagram of orbitals in complex 5.
Scheme 6. Competition in the stabilization of the π lone pair at C:
by the P substituent versus the metal.
Conclusion
Table 3. Comparison of bond lengths and angles in 5.
We have presented here the first examples of the coordi-
nation of monoanion 2– and dianions 22– and 32– toward
CoII. The reactivity of 2– leads to the formation of a homo-
leptic complex, best seen as a paramagnetic zwitterionic
species. The coordination of the two dianions results in the
formation of related dinuclear species containing two bridg-
ing ligands. The metal–ligand interaction is much stronger
in the case of ligand 22–, which transfers more efficiently its
electronic density. On the other hand, the two lone pairs at
C of the ligand 32– are more efficiently stabilized by the
Bond
RX
DFT
Δ|RX – DFT|
Co11–Co12
Co11–C1
C1–Co12
C1–P9
C1–P8
P9–S5
P8–S4
Co11–S5
Co11–S6
2.47
2.05
2.06
1.74
1.74
2.02
2.02
2.35
2.35
2.42
1.93
1.93
1.77
1.77
2.04
2.04
2.33
2.33
0.04
0.12
0.13
0.03
0.03
0.02
0.02
0.02
0.002
The relative stability of the triplet compared to the sing- P(O)OR2 substituents. The formation of the paramagnetic
let can be explained when one looks at the frontier orbitals complex 5 was rationalized by DFT calculations. The redox
of 5 in both states. The SOMO–1 and the SOMO of com- behavior of complexes 5 and 6 are currently being studied
plex 5 in the triplet state are shown in Figure 4. The in our laboratory, as both oxidation and reduction should
SOMO–1 (Figure 4, left) shows an antibonding interaction lead to profound modifications as illustrated by the shape
of the two dx2–y2 orbitals at the Co centers. This orbital of the SOMO orbitals of complex 5.
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Coordination Behavior of O–C–O and S–C–S Anions
tions, views of computed structures, cartesian coordinates, and the
three lower frequencies for each optimized structure.
Experimental Section
General: All reactions were routinely performed under an inert at-
mosphere of argon or nitrogen by using Schlenk and glovebox tech-
niques and dry deoxygenated solvents. Dry tetrahydrofuran and
hexanes were distilled by using Na/benzophenone; dry dichloro-
methane was distilled by using P2O5; and dry toluene with Na.
Nuclear magnetic resonance spectra were recorded on a Bruker
AC-300 SY spectrometer operating at 300.0 MHz for 1H,
75.5 MHz for 13C, and 121.5 MHz for 31P. Solvent peaks were used
Acknowledgments
The authors thank the Centre National de la Recherche Sci-
entifique (CNRS) and the Ecole Polytechnique for the financial
support of this work and IDRIS for the allowance of computer
time (project no. 091616).
as an internal reference relative to Me4Si for H and 13C chemical
1
shifts (ppm); 31P chemical shifts are relative to a 85% H3PO4 exter-
nal reference. Coupling constants are given in Hertz. The following
abbreviations are used: s, singlet; br. s, broad singlet; t, triplet.
Monoanion 2–,[13] and dianions 22– and 32– were prepared accord-
ing to literature procedures.[3] CoCl2 was bought as the hydrate and
dried by heating under vacuum. All other reagents and chemicals
were obtained commercially and used as received.
[1] T. K. Panda, P. W. Roesky, Chem. Soc. Rev. 2009, 38, 2782–
2804.
[2] R. G. Cavell, in: The Chemistry of Pincer Compounds (Eds.: D.
Morales-Morales, C. M. Jensen), Elsevier, Amsterdam, 2007,
pp. 311–355. For the synthesis of dianion 12–, see: a) C. M.
Ong, D. W. Stephan, J. Am. Chem. Soc. 1999, 121, 1483–1484;
b) A. Kasani, R. P. K. Babu, R. McDonald, R. G. Cavell, An-
gew. Chem. Int. Ed. 1999, 38, 1483–1484.
Synthesis of Complex 4: CoCl2 (20.7 mg, 0.16 mmol) was added to
a solution of monoanion 2– (143.6 mg, 0.32 mmol) in toluene
(4 mL) under an argon atmosphere at room temperature. The solu-
tion was left stirring for 15 h at room temperature, then filtered
and dried. The solvent was evaporated under vacuum to give the
title compound as a green solid (80%). Single crystals suitable for
X-ray analysis were grown from a concentrated solution of 5 in
toluene. 1H NMR (300 MHz, CD2Cl2): δH = 8.70 (br. s, meta-
phenyl), 6.65 (br. s, para-phenyl), 6.32 (br. s, ortho-phenyl) ppm.
13C NMR (75.5 MHz, CD2Cl2): δC = 227.2 (br. s, Cipso), 148.0 (s,
CH para-phenyl), 146.4 (s, CH meta-phenyl), 129.2 (br. s, CH or-
tho-phenyl) ppm. 31P NMR (121.5 MHz, CD2Cl2): δP = 4.1 (br. s)
ppm. C50H42CoP4S4·C4H8O (1026.1): calcd. C 63.21, H 4.92; found
C 63.07, H 5.11.
[3] For the synthesis of dianion 22– and 32–, see: T. Cantat, L.
Ricard, P. Le Floch, N. Mézailles, Organometallics 2006, 25,
4965–4976.
[4] For reviews, see: a) R. G. Cavell, in: The Chemistry of Pincer
Compounds (Eds.: D. Morales-Morales, C. M. Jensen), Elsevier,
Amsterdam, 2007, pp. 311–346; b) N. Mézailles, P. Le Floch,
in: The Chemistry of Pincer Compounds (Eds.: D. Morales-Mo-
rales, C. M. Jensen), Elsevier, Amsterdam, 2007, pp. 235–271;
c) T. Cantat, N. Mézailles, A. Auffrant, P. Le Floch, Dalton
Trans. 2008, 1957–1972; d) H. Heuclin, M. Fustier, A. Auffr-
ant, N. Mézailles, Lett. Org. Chem. 2010, 7, 596–611.
[5] a) R. G. Cavell, R. P. K. Babu, A. Kasani, R. McDonald, J.
Am. Chem. Soc. 1999, 121, 5805–5806; b) R. P. K. Babu, R.
McDonald, R. G. Cavell, Organometallics 2000, 19, 3462–3465;
c) R. G. Cavell, R. P. K. Babu, K. Aparna, J. Organomet.
Chem. 2001, 617–618, 158–169; d) M. T. Gamer, M. Rastatter,
P. W. Roesky, Z. Anorg. Allg. Chem. 2002, 628, 2269–2272; e)
N. D. Jones, G. Lin, R. A. Gossage, R. McDonald, R. G. Cav-
ell, Organometallics 2003, 22, 2832–2841; f) G. Lin, N. D.
Jones, R. A. Gossage, R. McDonald, R. G. Cavell, Angew.
Chem. Int. Ed. 2003, 42, 4054–4057; g) N. D. Jones, R. G. Cav-
ell, J. Organomet. Chem. 2005, 690, 5485–5496; h) T. Cantat,
M. Demange, N. Mézailles, L. Ricard, Y. Jean, P. Le Floch,
Organometallics 2005, 24, 4838–4841; i) T. Cantat, L. Ricard,
N. Mézailles, P. Le Floch, Organometallics 2006, 25, 6030–
6038; j) T. K. Panda, P. W. Roesky, P. Larsen, S. Zhang, C.
Wickleder, Inorg. Chem. 2006, 45, 7503–7508.
[6] For coordination chemistry of dianions toward group 2 metal
centers, see: a) L. Orzechowski, G. Jansen, S. Harder, Angew.
Chem. Int. Ed. 2009, 48, 3525–3829; b) L. Orzechowski, G.
Jansen, S. Harder, J. Am. Chem. Soc. 2006, 128, 14676–14684;
c) L. Orzechowski, S. Harder, Organometallics 2007, 26, 2144–
2148; d) L. Orzechowski, S. Harder, Organometallics 2007, 26,
5501–5506.
[7] For coordination chemistry of dianions toward rare-earth-
metal centers, see: a) T. Cantat, F. Jaroschick, L. Ricard, F.
Nief, N. Mézailles, P. Le Floch, Chem. Commun. 2005, 5178–
5180; b) T. Cantat, F. Jaroschick, L. Ricard, P. Le Floch, F.
Nief, N. Mézailles, Organometallics 2006, 25, 1329–1332; c) A.
Buchard, A. Auffrant, L. Ricard, X. F. Le Goff, R. H. Platel,
C. K. Williams, P. Le Floch, Dalton Trans. 2009, 10219–10222;
d) D. P. Mills, L. Soutar, W. Lewis, A. J. Blake, S. T. Liddle, J.
Am. Chem. Soc. 2010, 132, 14379–14381; e) M. Fustier, X. F.
Le Goff, P. Le Floch, N. Mézailles, J. Am. Chem. Soc. 2010,
132, 13108–13110.
Synthesis of Complex 5: CoCl2 (41.4 mg, 0.32 mmol) was added to
a solution of dianion 22– (143.6 mg, 0.32 mmol) in toluene (4 mL)
under an argon atmosphere at room temperature. The solution was
left stirring for 12 h at room temperature and was filtered. The title
compound was obtained as a brown powder after evaporation of
the solvent (75%). Single crystals suitable for X-ray analysis were
obtained by a slow diffusion of hexanes into a concentrated solu-
1
tion of 5 in dichloromethane. H NMR (300 MHz, CD2Cl2): δH
=
13.66 (s, 8 H, ortho-phenyl), 9.69 (s, 8 H, meta-phenyl), 9.05 (t, J
= 7 Hz, 4 H, para-phenyl), 4.57 (t, J = 7 Hz, 4 H, para-phenyl),
2.79 (s, 8 H, meta-phenyl), –9.12 (s, 8 H, ortho-phenyl) ppm. 13C
NMR (75.5 MHz, CD2Cl2): δC = 148.1 (s, ortho-phenyl), 136.2 (s,
para-phenyl), 130.3 (s, meta-phenyl), 125.6 (s, para-phenyl), 121.4
(s, meta-phenyl) ppm. 31P NMR (121.5 MHz, CD2Cl2): δP = 187
(s) ppm. C50H42Co2P4S4 (1012.9): calcd. C 59.41, H 3.99; found C
59.69, H 3.88.
Synthesis of Complex 6: CoCl2 (54.5 mg, 0.42 mmol) was added to
a suspension of dianion 3 (150 mg, 0.42 mmol) in toluene (5 mL)
under an argon atmosphere. The solution was heated at 80 °C for
3h. The title compound was isolated as a purple-red solid after
filtration and washing with toluene (3ϫ2 mL; yield: 83%). Single
crystals suitable for X-ray diffraction analysis were obtained by
slow diffusion of hexanes into a concentrated solution of 6 in THF.
1H NMR (300 MHz, [D8]THF): δH = 6.4 [br. s, 4 H, CH(CH3)2],
1.23 [br. s, 12 H, CH(CH3)2], 1.06 [br. s, 12 H, CH(CH3)2] ppm.
13C NMR (75.5 MHz, [D8]THF): δC = 74.4 [br. s, CH(CH3)2], 25.9
[br. s, CH(CH3)2] ppm. 31P NMR (121.5 MHz, [D8]THF): δP = 63
(br. s) ppm. C42H88Cl4Co2Li4O16P4 (1260.5): calcd. C 40.02, H
7.04; found C 39.86, H 6.87.
[8] For coordination chemistry of dianions toward uranium, see:
a) T. Cantat, T. Arliguie, A. Noel, P. Thuéry, M. Ephritikhine,
P. Le Floch, N. Mézailles, J. Am. Chem. Soc. 2009, 131, 963–
970; b) J.-C. Tourneux, J.-C. Berthet, P. Thuéry, N. Mézailles,
P. Le Floch, M. Ephritikhine, Dalton Trans. 2010, 39, 2494–
Supporting Information (see footnote on the first page of this arti-
cle): Crystallographic details, computational details for calcula-
Eur. J. Inorg. Chem. 2011, 2540–2546
© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
2545

H. Heuclin, T. Cantat, X. F. Le Goff, P. Le Floch, N. Mezailles
FULL PAPER
2496; c) O. Cooper, J. McMaster, W. Lewis, A. J. Blake, S. T.
Liddle, Dalton Trans. 2010, 39, 5074–5076; d) J.-C. Tourneux,
J.-C. Berthet, T. Cantat, P. Thuéry, N. Mézailles, P. Le Floch,
M. Ephritikine, J. Am. Chem. Soc., article ASAP, DOI:
10.1021:ja201276h.
[18]
H. Heuclin, D. Grünstein, X. F. Le Goff, P. Le Floch, N.
Mézailles, Dalton Trans. 2010, 492–499.
[19]
K. W. Henderson, A. R. Kennedy, D. J. MacDougall, D. Stra-
chan, Acta Crystallogr., Sect. C: Cryst. Struct. Commun. 2003,
59, m49–m51.
[9] a) P. Imhoff, C. J. Elsevier, J. Organomet. Chem. 1989, 361,
C61–C65; b) P. Imhoff, R. Vanasselt, C. J. Elsevier, M. C. Zout-
berg, C. H. Stam, Inorg. Chim. Acta 1991, 184, 73–87; c) P.
Imhoff, R. V. Asselt, J. M. Ernsting, K. Vrieze, C. J. Elsevier,
Organometallics 1993, 12, 1523–1536; d) P. Imhoff, J. H.
Gülpen, K. Vrieze, W. J. J. Smeets, A. Spek, C. J. Elsevier, Inorg.
Chim. Acta 1995, 235, 77–88.
[10] a) M. Fang, N. D. Jones, R. Lukowski, J. Tjathas, M. J. Fergu-
son, R. G. Cavell, Angew. Chem. Int. Ed. 2006, 45, 3097–3101;
b) M. Fang, N. D. Jones, K. Friesen, G. Lin, M. J. Ferguson,
R. McDonald, R. Lukowski, R. G. Cavell, Organometallics
2009, 28, 1652–1665.
[20]
M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria,
M. A. Robb, J. R. Cheeseman, J. A. Montgomery Jr., T.
Vreven, K. N. Kudin, J. C. Burant, J. M. Millam, S. S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N.
Rega, G. A. Petersson, H. Nakatsuji, M. Hada, M. Ehara, K.
Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y.
Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J. E. Knox, H. P.
Hratchian, J. B. Cross, V. Bakken, C. Adamo, J. Jaramillo, R.
Gomperts, R. E. Stratmann, O. Yazyev, A. J. Austin, R.
Cammi, C. Pomelli, J. W. Ochterski, P. Y. Ayala, K. Morok-
uma, G. A. Voth, P. Salvador, J. J. Dannenberg, V. G. Zakrzew-
ski, S. Dapprich, A. D. Daniels, M. C. Strain, O. Farkas, D. K.
Malick, A. D. Rabuck, K. Raghavachari, J. B. Foresman, J. V.
Ortiz, Q. Cui,A. G. Baboul, S. Clifford, J. Cioslowski, B. B. Ste-
fanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. L.
Martin, D. J. Fox, T. Keith, M. A. Al-Laham, C. Y. Peng, A.
Nanayakkara, M. Challacombe, P. M. W. Gill, B. Johnson, W.
Chen, M. W. Wong, C. Gonzalez, J. A. Pople, Gaussian 03, rev.
C.02, Gaussian, Inc., Wallingford, CT, 2004.
[11] M. Blug, H. Heuclin, T. Cantat, X. F. Le Goff, N. Mézailles,
P. Le Floch, Organometallics 2009, 28, 1966–1972.
[12] S. Al-Benna, M. J. Sarsfield, M. Thornton-Pett, D. L. Ormsby,
P. J. Maddox, P. Brès, M. Bochmann, J. Chem. Soc., Dalton
Trans. 2000, 4247–4257.
[13] W.-P. Leung, C.-L. Wan, T. C. W. Mak, Organometallics 2010,
29, 1622–1628.
[14] T. W. McGaughy, B. M. Fung, Inorg. Chem. 1972, 11, 2728–
2733.
[15] R. S. Drago, J. I. Zink, R. M. Richman, W. D. Perry, J. Chem.
Educ. 1974, 51, 371–376.
[16] A. A. Danopoulos, J. A. Wright, W. B. Motherwell, S. Ellwood,
Organometallics 2004, 23, 4807–4810.
[17] T. Cantat, L. Ricard, N. Mézailles, P. Le Floch, Organometal-
lics 2006, 25, 6030–6038.
[21] J. P. Perdew, K. Burke, M. Ernzerhof, Phys. Rev. Lett. 1996,
77, 3865–3868.
[22] N. Godbout, D. R. Salahub, J. Andzelm, E. Wimmer, Can. J.
Chem. 1992, 70, 560–571.
Received: February 11, 2011
Published Online: April 21, 2011
2546
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© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2011, 2540–2546