A ruthenium(II) complex stabilized by a highly fluorinated PCP pincer ligand

Article abstract of DOI:10.1021/om050422n

A novel Ru(II) complex containing an electron-poor, highly fluorinated PCP^ArF pincer ligand has been synthesized in good yield via a transcyclometalation reaction. The complex has been fully characterized by elemental analysis, 1D and 2D NMR techniques, UV-vis spectroscopy, and cyclic voltammetry. Single-crystal X-ray structural analysis and DFT calculations were performed. The structural features and electronic properties of the remarkably stable PCP^ArF-Ru(II) complex 4 have been investigated and show unanticipated differences compared to its protio analogue.

Full text of DOI:10.1021/om050422n

Organometallics 2005, 24, 4553-4557
4553
A Ruthenium(II) Complex Stabilized by a Highly
Fluorinated PCP Pincer Ligand
Marcella Gagliardo,† Preston A. Chase,† Martin Lutz,‡ Anthony L. Spek,‡,§
Frantisek Hartl,| Remco W. A. Havenith, Gerard P. M. van Klink,† and
Gerard van Koten*,†
Debye Institute, Organic Chemistry and Catalysis, Padualaan 8, 3584 CH Utrecht, The
Netherlands, Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry,
Padualaan 8, 3584 CH Utrecht, The Netherlands, van’t Hoff Institute for Molecular Sciences,
Molecular Photonic Materials Group, University of Amsterdam, Nieuwe Achtergracht 166,
1018 WV Amsterdam, The Netherlands, and Debye Institute, Theoretical Chemistry Group,
Padualaan 8, 3584 CH Utrecht, The Netherlands
Received May 27, 2005
A novel Ru(II) complex containing an electron-poor, highly fluorinated PCPArF pincer ligand
has been synthesized in good yield via a transcyclometalation reaction. The complex has
been fully characterized by elemental analysis, 1D and 2D NMR techniques, UV-vis
spectroscopy, and cyclic voltammetry. Single-crystal X-ray structural analysis and DFT
calculations were performed. The structural features and electronic properties of the
remarkably stable PCPArF-Ru(II) complex 4 have been investigated and show unanticipated
differences compared to its protio analogue.
Introduction
stituents.5 As reported recently, PCP-Pd(II) complexes
with P(C6F5)2 groups6 and PCP-Rh(I) and -Rh(III)
compounds7 containing P(pyrrolyl)2 donors are the first
examples where PCP complexes incorporate electron-
poor, strong π-accepting phosphines. The altered elec-
tronics can have a profound impact on the molecular
structure of the complexes and reactivity. As PCP-Ru-
(II) complexes are highly active catalysts in the transfer
hydrogenation of ketones5e,8 and possess interesting
redox and photophysical properties,9 the effects induced
Cyclometalated organometallic complexes containing
monoanionic, potentially terdentate coordinating ECE-
pincer ligands (E ) N, P, O, S; pincer ) [C6H3(CH2ERx)2-
2,6]-) are widely applicable in such diverse fields as
catalysis and mechanistic investigations,1 supramolecu-
lar chemistry,2 and sensor materials.3 Facile variation
of the steric and electronic properties of the pincer
ligand have allowed for the fine tuning of effects in the
aforementioned applications. In particular, terdentate
PCP pincer complexes of Ru, Rh, Ir, Ni, Pd, and Pt have
been used as efficient reagents and catalysts for a
variety of organic transformations such as allylation of
aldehydes, atom-transfer radical polymerization, dehy-
drogenation of alkanes, Heck olefin arylation, and
Suzuki coupling of arylboronic acids with aryl bro-
mide.1,4 With regard to PCP-Ru(II) complexes, the
majority of species reported to date contain phosphine
donor atoms with electron-releasing alkyl or aryl sub-
(4) Representative examples: (a) Jensen, C. M. Chem. Commun.
1999, 2443. (b) Liu, F.; Pak, E. B.; Singh, B.; Jensen, C. M.; Goldman,
A. S. J. Am. Chem. Soc. 1999, 121, 4086. (c) Gibson, S.; Foster, D F.;
Eastham, G. R.; Tooze, R. P.; Cole-Hamilton, D. J. Chem. Commun.
2001, 779. (d) Kanzelberger, M.; Zhang, X.; Emge, T. J.; Goldman, A.
S.; Zhao, J.; Incarvito, C.; Hartwig, J. F. J. Am. Chem. Soc. 2003, 125,
13644. (e) Kjellgren, J.; Sunde´n, H.; Szabo´, K. J. J. Am. Chem. Soc.
2004, 126, 474. (f) Wallner, O. A.; Szabo´, K. J. Org. Lett. 2004, 6, 1831.
(g) Go¨ttker-Schnetmann, I.; White, P. S.; Brookhart, M. Organome-
tallics 2004, 23, 1766. (h) Go¨ttker-Schnetmann, I.; White, P. S.;
Brookhart, M. J. Am. Chem. Soc. 2004, 126, 1804. (i) Solin, N.;
Kjellgren, J.; Szabo´, K. J. J. Am. Chem. Soc. 2004, 126, 7026. (j) Zhao,
J.; Goldman, A. S.; Hartwig, J. F. Science 2005, 307, 1080. (k) Solin,
N.; Wallner, O. A.; Szabo´, K. J. Org. Lett. 2005, 6, 689. (l) Ray, A.;
Zhu, K.; Kissin, Y. V.; Cherian, A. E.; Coates, G. W.; Goldman, A. S.
Chem. Commun. 2005, 3388.
(5) (a) Karlen, T.; Dani, P.; Grove, D. M.; Steenwinkel, P.; van Koten,
G. Organometallics 1996, 15, 5687. (b) Jia, G.; Lee, H. M.; Xia, H. P.;
Williams, I. D. Organometallics 1996, 15, 5453. (c) van der Boom, M.
E.; Kraatz, H.-B.; Hassner, L.; Ben-David, Y.; Milstein, D. Organome-
tallics 1999, 18, 3873. (d) Gusev, D. G.; Dolgushin, F. M.; Antipin, M.
Y. Organometallics 2000, 19, 3429. (e) Amoroso, D.; Jabri, A.; Yap, G.
P. A.; Gusev, D. G.; Dos Santos, E. N.; Fogg, D. E. Organometallics
2004, 23, 4047.
(6) Chase, P. A.; Gagliardo, M.; van Klink, G. P. M.; van Koten, G.
Organometallics 2005, 24, 2016.
(7) Kossoy, E.; Iron, M. A.; Rybtchinski, B.; Ben-David, Y.; Shimon,
L. J. W.; Konstantinovski, L.; Martin, J. M. L.; Milstein, D. Chem. Eur.
J. 2005, 11, 2319.
(8) (a) Dani, P.; Karlen, T.; Gossage, R. A.; Gladiali, S.; van Koten,
G. Angew. Chem., Int. Ed. 2000, 39, 743. (b) Medici, S.; Gagliardo, M.;
Williams, S. B.; Chase, P. A.; Gladiali, S.; Lutz, M.; Spek, A. L.; van
Klink, G. P. M.; van Koten, G. Helv. Chim. Acta 2005, 88, 694.
(9) Gagliardo, M.; Dijkstra, H. P.; Coppo, P.; Lutz, M.; Spek, A. L.;
van Klink, G. P. M.; van Koten, G. Organometallics 2004, 23, 5833.
* To whom correspondence should be addressed: E-mail:
g.vankoten@chem.uu.nl. Fax: +31-30-252-3615. Tel: +31-30-253-3120.
† Debye Institute, Organic Chemistry and Catalysis.
‡ Bijvoet Center for Biomolecular Research.
§ To whom crystallographic inquiries may be directed. E-mail:
a.l.spek@chem.uu.nl.
| University of Amsterdam.
Debye Institute, Theoretical Chemistry Group (affiliated with
Debye Institute, Organic Chemistry and Catalysis).
(1) Albrecht, M.; van Koten, G. Angew. Chem., Int. Ed. 2001, 41,
3750. (b) van der Boom, M. E.; Milstein, D. Chem. Rev. 2003, 103, 1759.
(c) Singleton, J. T. Tetrahedron 2003, 59, 1837.
(2) Representative examples: (a) Sutter, J.-P.; Grove, M. D.; Beley,
M.; Collin, J.-P.; Veldman, N.; Spek, A. L.; Sauvage, J.-P.; van Koten,
G. Angew. Chem., Int. Ed. Engl. 1994, 33, 1282. (b) Omnes, L.; Timini,
B. A.; Gelbrich, T.; Hursthouse, M. B.; Luckhurst, G. R.; Bruce, D. W.
Chem. Commun. 2001, 2248. (c) Aiello, I.; Dattilo, D.; Ghedini, M.;
Bruno, A.; Termine, R.; Golemme, A. Adv. Mater. 2002, 14, 1233.
(3) Albrecht, M.; Lutz, M.; Spek, A. L.; van Koten, G. Nature 2002,
406, 970.
10.1021/om050422n CCC: $30.25 © 2005 American Chemical Society
Publication on Web 08/18/2005

4554 Organometallics, Vol. 24, No. 19, 2005
Gagliardo et al.
Figure 1. Molecular structures of 4 (left) and 5 (right) in the crystal state. Ellipsoids are drawn at the 30% probability
level. Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 4: Ru1-C1 ) 2.0330(17),
Ru1-P1 ) 2.2905(5), Ru1-P2 ) 2.3410(5), Ru1-P3 ) 2.3154(4), Ru1-Cl1 ) 2.4121(4), P1-C7 ) 1.8275(18), P2-C20 )
1.8322(18), P1-C8 ) 1.8474(18), P1-C14 ) 1.8531(18), P2-C21 ) 1.8520(18), P2-C27 ) 1.8468(18); P1-Ru1-P2 )
159.006(17), Cl1-Ru1-P3 ) 166.925(16), Cl1-Ru1-C1 ) 96.46(5). Selected bond lengths (Å) and angles (deg) for 5: Ru1-
C1 ) 2.073(3), Ru1-P1 ) 2.3039(9), Ru1-P2 ) 2.2937(9), Ru1-P3 ) 2.2174(9), Ru1-Cl1 ) 2.4797(8), P1-C2 ) 1.838(3),
P1-C8 ) 1.826(3), P2-C21 ) 1.819(3), P2-C27 ) 1.835(4); P1-Ru1-P2 ) 151.21(3), Cl1-Ru1-P3 ) 121.08(9), Cl1-
Ru1-C1 ) 153.35(8).
Scheme 1. Synthesis of [RuCl(PCPArF)(PPh3)] (4)
via a Transcyclometalation Reactiona
the PCP ligand gave complex 4 in good yield (80%)
(Scheme 1), which can be isolated as a remarkably air-
and water-stable red powder after workup. In general,
PCP-Ru(II) species are readily oxidized by atmospheric
O2.5 Complex 4 can be stored in air over months, and
its purification can be conveniently undertaken by
column chromatography.
The structure of 4 in solution was assigned using 1H,
31P{1H}, 13C{1H}, and 19F NMR spectroscopy and 2D
NMR techniques (19F-19F COSY and 1H-19F HOESY).
The room-temperature 31P{1H} NMR spectrum exhibits
a doublet at 36.5 ppm (2JP-P ) 29 Hz) for the P(C6F5)
groups and a triplet at 35.4 ppm (2JP-P ) 29 Hz) for
the PPh3 ligand. This, along with the multiplicity of the
1H NMR signals, is consistent with trans positioning of
the PCPArF phosphorus atoms and with the PPh3 ligand
cis to the P(C6F5)2 groups.5,13
a Reaction conditions: (i) C6H6, reflux, 14 h.
In the 19F NMR spectrum, two resonances are found
for the para fluorine (-152.6 and -153.3 ppm), indicat-
ing that the C6F5 rings are diastereotopic. These find-
ings suggest that the square-pyramidal Cs-symmetric
arrangement previously observed for the PCP-Ru(II)
complexes is retained.5,13 The doublet for the P(C6H5)2
groups in the protio complex 5 falls in the same region
(37.0 ppm) as the P(C6F5)2 groups in 4. However, in 4
the phosphorus resonance of the PPh3 ligand is consid-
erably upfield compared to the case for its protio
analogue 5 (81.0 ppm). This shielding of ca. 50 ppm
cannot be exclusively explained on considering the donor
characteristics of the phosphorus atoms of the P(C6F5)2
groups. The signal of Cipso in the 13C{1H} NMR spectrum
is also considerably shifted to higher field (149.5 ppm;
2JC-P ) 10 Hz) in comparison to what was previously
by incorporation of an electron-poor PCP ligand were
investigated. Here, we report the synthesis, electronic
properties, and unusual structure of the PCP-Ru(II)
complex 4 (Scheme 1) obtained from the highly fluori-
nated [C6H4(CH2P(C6F5)2)2-1,3]5 (PCPArF, 1; Scheme 1)
pincer ligand.
Results and Discussion
Direct cyclometalation5 of 1 with [RuCl2(PPh3)3],
successfully applied previously in the preparation of Ru-
(II) complexes incorporating (bulky) electron-donating
alkyl- and arylphosphine pincer ligands, did not yield
4. The transcyclometalation (TCM) reaction is an al-
ternative method for efficient preparation of achiral10
and chiral8b,11 [RuCl(PCP)(PPh3)] complexes. Exchange
of the NCN ligand in the NCN-Ru(II) precursor 212 by
(12) Sutter, J.-P.; James, S. L.; Steenwinkel, P.; Grove, D. M.;
(10) Dani, P.; Karlen, T.; Gossage, R. A.; Smeets, W. J. J.; Spek, A.
L.; van Koten, G. J. Am. Chem. Soc. 1997, 119, 11317.
(11) Dani, P.; Albrecht, M.; van Klink, G. P. M.; van Koten, G.
Organometallics 2000, 19, 4468.
Veldman, N.; Spek, A. L.; van Koten, G. Organometallics 1996, 15,
941.
(13) Dani, P.; van Klink, G. P. M.; van Koten, G. Eur. J. Inorg. Chem.
2001, 7, 1465.

An Ru(II) Complex Stabilized by a PCP Pincer Ligand
Organometallics, Vol. 24, No. 19, 2005 4555
2
observed for 5 (172.5 ppm; JC-P ) 20 Hz).13 It can be
Table 1. Absorption and Electrochemical Data for
Complexes 4 and 5
noted that the much larger 2JC-P value for Cipso in 5, in
comparison to that in 4, is caused by the chloride ligand
being positioned trans to Cipso
a,b
λmax
/
ꢀmaxa,b/103 dm3
E1/2(Ru(II)/
compd
nm
mol-1 cm-1
Ru(III))a,c/V
.
4
5
523
630
1.22
1.25
0.39
An X-ray crystal structure determination of 4 (Figure
1, left) revealed that the fluorinated pincer ligand has
a profound effect on the metal coordination environ-
ment. The molecular structures of 4 and its solvent-free
protio analogue 514 (Figure 1, right) both show the Ru-
(II) center to be in a distorted-square-pyramidal geom-
etry with σ parameters15 of 0.13 and 0.04, respectively.
Interestingly, the apical position of 4 is occupied by the
Cipso atom of the arene in the PCPArF ligand, whereas
in 5 the phosphorus atom of the PPh3 ligand occupies
this position. The basal plane of 4, formed by P1, P2,
P3, and Cl1, is a puckered square due to the ring strain
of the chelated PCP ligand. In 5 the basal plane is
almost planar. A comparison of the distances between
Ru and the PPh3 ligand in 4 and 5 shows that the Ru-P
bond is significantly elongated in 4 by 0.1 Å, which can
be ascribed to the trans influence of the chloride ligand.
In the majority of square-pyramidal five-coordinated
metal complexes, the metal atom is located above the
basal plane. In 5 the Ru(II) center lies 0.52 Å above this
plane. A quite different situation is observed for 4, with
the Ru(II) center placed in the basal plane with a
deviation of only 0.05 Å. Such an arrangement is often
found in (pseudo)octahedral complexes. Indeed, in 4 a
weak interaction trans to C1 is found between Ru1 and
H34 of the PPh3 ligand. The Ru1-H34 distance of 2.86
Å is shorter than the sum of their contact radii.16 This
Ru-H interaction is also reflected in tilting of the PPh3
ligand with respect to the Ru-P bond orientation. The
Ru1-P3-C33 angle of 103.38(6)° is much smaller than
the corresponding angles involving C39 and C45 (120.43-
(6) and 125.24(6)°, respectively). The Ru-P-C angles
of the PPh3 ligand in 5 without a Ru-H interaction vary
much less (113.97(12)-117.20(11)°). Although quite
some broadening of the PPh3 peaks is noted in the low-
temperature 1H NMR spectrum, this intramolecular
interaction is not explicitly observed in solution.
-0.01
a Measured in CH2Cl2 at 298 K. b Absorption maxima and
absorption molar coefficients of bands in the visible spectral region.
c Redox potentials (E1/2) in V vs Fc/Fc+.
Figure 2. Cyclic voltammograms of complexes 4 and 5
measured in CH2Cl2 at 298 K (0.1 M TBAH; scan rate 100
mV s-1).
ligand in 4 takes the apical position rather than PPh3
taking this position, as previously postulated.5
DFT calculations confirm that the calculated geom-
etry of complex 4 compares favorably to the experimen-
tally determined crystal structure. However, at this
point, it is difficult to state whether the stability of this
configuration is mainly due to the electronic influence
of the P(C6F5) or is due to steric reasons.
Electrochemical studies and electronic absorption
spectra show that the redox and spectroscopic properties
of 4 change considerably compared to those of 5, due to
the presence of the strongly electron withdrawing
fluorinated groups at the donor phosphorus atoms (see
Table 1). The cyclic voltammograms of 4 and its protio
analogue 5 (Figure 2), measured in CH2Cl2, exhibit a
single reversible one-electron wave corresponding to the
Ru(II)/Ru(III) couple. The current for both peaks is
linearly dependent on ν1/2 for the scan rates studied
(0.05-1 V s-1), indicating completely reversible, diffu-
sion-controlled processes. As expected, the profound
stabilization of the Ru d(π)-based orbitals in 4 by
π-accepting P(C6F5) groups accounts for the drastic
positive shift in the Ru(II)/Ru(III) redox couple (Table
1). These findings correlate with the electronic spectra
(Table 1). The UV regions of the spectra of the red
complex 4 and green complex 5 exhibit at wavelengths
below 350 nm intense ligand-centered (LC) π f p*
electronic transitions. In the visible region, broad, much
less intense absorptions at 523 and 630 nm for 4 and
5,5a respectively, are observed. Interestingly, the ener-
gies of these bands increase in the order 5 < 4,
suggesting that their position is strongly sensitive to
the varied π-acceptor properties of the substituents on
the phosphorus. The assignments of the lowest energy
absorption bands have been based on the ground-state
DFT calculations on complexes 4 and 5. A three-
dimensional plot of the HOMOs and LUMOs of 4 and 5
is depicted in Figure 3. The HOMOs of 4 (-5.62 eV) and
5 (-4.72 eV) are predominantly metalin character. The
higher energy of the HOMO of 5 (∆E ) 0.90 eV) is
Fluxional behavior was observed in the 19F NMR
spectrum at room temperature. The signal for the ortho
fluorines found as a broad singlet at -128.77 ppm at
room temperature splits into four signals at -124.20,
-128.32, -130.20, and -134.67 ppm on cooling to -40
°C. Low-temperature 19F-19F COSY shows that the
middle two peaks correlate with one C6F5 ring while the
outer signals relate to the other. A similar situation is
observed with the meta fluorine signals, but the para
fluorine signals remain unchanged. As the C6F5 rings
on each P atom are diastereotopic, these data imply
restricted P-C6F5 rotation; the C6F5 group proximal to
1
the PPh3 was assigned by a low-temperature H-19F
HOESY NMR cross-peak between the ortho fluorines
at -128.32 with the ortho protons of the PPh3. This
fluxional behavior was not observed for 5,5b,13 which is
in line with the larger overall steric bulk of C6F5 vs
C6H5. Still, the Cipso atom of the cyclometalated PCPArF
(14) Lutz, M.; Dani, P.; Spek, A. L.; van Koten, G. Private com-
munication to the Cambridge Crystallographic Database, refcode
JUJXOB, 1999.
(15) Addison, A. W.; Rao, T. N.; Reedijk, J.; van Rijn, J.; Verschoor,
G. C. J. Chem. Soc., Dalton Trans. 1984, 1349.
(16) Bondi, A. J. Phys. Chem. 1964, 68, 441.

4556 Organometallics, Vol. 24, No. 19, 2005
Gagliardo et al.
Figure 3. Contour plots of the HOMO and LUMO of 4 (top) and the HOMO, LUMO and LUMO + 1 of 5 (bottom) calculated
at the B3LYP/LANL2-DZ level.
consistent with the results obtained by the electrochemi-
cal studies, which reveal that 5 is more prone to
oxidation than 4. The LUMO of 4 (-2.44 eV) is sub-
stantially delocalized over the PCPArF ligand, suggesting
that the most intense transition in the visible region
centered at 523 nm posseses a significant metal-to-
ligand-charge-transfer (MLCT) character. However, the
LUMO of 5 (-1.76 eV) is clearly different and posseses
a strong d-metal character. Thus, it is tempting to
assign the lowest energy transition of 5 centered at 630
nm as d-d in nature. However, it cannot be excluded
that MLCT transitions occurring from the HOMO to
other unoccupied molecular orbitals localized on the
ligands, such as the LUMO + 1 (Figure 3), contribute
to the observed band. Calculations on 4 and 5 are
ongoing in order to assign all the bands observed in the
recorded electronic spectra.
Experimental Section
General Procedures. All reactions were performed under
an atmosphere of dry oxygen-free nitrogen using Schlenk
techniques or in a nitrogen-filled MBraun 150 G1 glovebox.
Pentane and toluene were dried over Na sand, THF and
diethyl ether were dried over Na/benzophenone, and CH2Cl2
was dried over CaH2. All solvents were freshly distilled under
nitrogen prior to use. CD2Cl2 was purchased from Cambridge
Isotope Laboratories, dried over CaH2, distilled prior to use,
and stored in a Schlenk flask over 4 Å molecular sieves under
nitrogen. 1D NMR spectra (1H (300.1 MHz), 13C (75.5 MHz),
19F (282.4 MHz), and 31P (121.4 MHz)) and 2D 19F-19F-COSY
experiments were recorded on a Varian Inova 300 MHz
spectrometer. 2D NMR 1H-19F-HOESY experiments were
performed using a Bruker AMX 300 MHz instrument (chemi-
cal shift values are reported in ppm (δ) and referenced
internally to residual solvent signals (1H, 13C) or externally
(19F, C6F6, δ -164.9; 31P, H3PO4 in D2O, δ 0). All reagents were
purchased from Acros Chemicals and used as received. Ligand
16 and complex 212 were synthesized via literature procedures.
Elemental analyses were performed by Dornis und Kolbe,
Mikroanalytisches Laboratorium, Mu¨lheim a. d. Ruhr, Ger-
many.
In conclusion, the present studies demonstrate that
C6F5 groups directly bound to the phosphorus centers
of PCP pincer ligands have a positive effect on the
stability of the metal ion and alter considerably the
structure and the electronic properties of 4. This may
be helpful for an understanding of the high stability of
the obtained configuration for 4. DFT calculations show
that the introduction of electron-withdrawing groups on
the phosphorus atoms of PCP pincer ligands impor-
tantly change the character of the frontier orbitals in
4. Work in progress is directed toward a detailed
understanding of the reactivity of 4 in both substitution
reactions and catalysis. Preliminary results suggest that
the remarkable stability and uncommon structural
features of 4, as presented here, significantly affect its
behavior in hydrogen transfer catalysis.
Cyclic Voltammetry Experiments. The electrochemical
experiments were performed with an EG&G Model 263A
potentiostat/galvanostat controlled by a Model 270/250 Re-
search Electrochemistry Software (version 4.23). A three-
electrode system was used, consisting of a platinum (Pt)
working electrode, a platinum (Pt) auxiliary electrode, and a
Ag/AgCl reference electrode separated from the test solution
by a glass frit. The experiments were carried out in CH2Cl2 at
room temperature under a nitrogen atmosphere with tetrabu-
tylammonium hexafluorophosphate (TBAH) as electrolyte (0.1
M). All potentials are reported relative to SCE. Linear volta-
mmograms were obtained at a scan rate of 100 mV s-1
Electronic Spectroscopic Measurements. UV-vis ab-
sorption spectra were obtained on a Varian Cary 1 spectro-
photometer using matched 1 cm cells and operating with 0.5
.

An Ru(II) Complex Stabilized by a PCP Pincer Ligand
Organometallics, Vol. 24, No. 19, 2005 4557
nm spectral resolution. Peak positions are given with an 0.5
nm accuracy.
[RuCl{C6H3(CH2P(C6F5)2)2-2,6}(PPh3)] (4). Ligand 1 (0.170
g; 0.2 mmol) was dissolved in dry benzene (5 mL) and
transferred, at room temperature, into a Schlenk flask con-
taining 2 (0.12 g; 0.2 mmol) in 10 mL of dry benzene. The
purple reaction mixture turned to deep red after 3 h upon
heating. After 14 h of heating under reflux, the solvent was
removed under vacuum. The obtained red residue was washed
with hexane until no more free m-bis(amino)aryl ligand 3 could
be detected by 1H NMR spectroscopy and dried under vacuum.
Computational Details. The geometries of 4 and 5 were
optimized at the B3LYP/LANL2-DZ level17 using GAMESS-
UK.18 Basis sets were obtained from the Extensible Compu-
tational Chemistry Environment Basis Set Database, Version
02/25/04, as developed and distributed by the Molecular
Science Laboratory, which is part of the Pacific Northwest
Laboratory, P.O. Box 999, Richland, WA 99352, and funded
by the U.S. Department of Energy.
1
2
Yield: 0.209 g (83%). H NMR (CD2Cl2): δ 3.90 (bd, JH-H
)
2
16 Hz, 2H, CH2), 4.16 (bd, JH-H ) 16 Hz, 2H, CH2), 6.77 (t,
Crystal Structure Determination of 4. Crystal data are
as follows: C50H22ClF20P3Ru, fw ) 1232.11, dark purple needle,
0.48 × 0.06 × 0.06 mm3, triclinic, P1h (No. 2), a ) 12.1513(1)
Å, b ) 14.5284(1) Å, c ) 15.7986(1) Å, R ) 101.9208(3)°, â )
106.6401(3)°, γ ) 112.0818(3)°, V ) 2315.99(3) Å3, Z ) 2, F )
1.767 g/cm3. A total of 78 348 reflections up to a resolution of
((sin θ)/λ)max ) 0.65 Å-1 were measured on a Nonius Kap-
paCCD diffractometer with a rotating anode and graphite
monochromator (λ ) 0.710 73 Å) at a temperature of 150(2)
K. An absorption correction based on multiple measured
reflections was applied (µ ) 0.619 mm-1, 0.72-0.96 correction
range). A total of 10 602 reflections were unique (Rint ) 0.0385).
The structure was solved with direct methods19 and refined
with SHELXL-9720 on F2 values of all reflections. Non-
hydrogen atoms were refined with anisotropic displacement
parameters. All hydrogen atoms were located in the difference
Fourier map and refined as rigid groups. A total of 676
parameters were refined with no restraints. R1/wR2 (I > 2σ-
(I)): 0.0262/0.0594. R1/wR2 (all reflections): 0.0344/0.0627. S
) 1.038. The residual electron density was between -0.47 and
0.40 e/Å3. Geometry calculations, drawings, and checking for
higher symmetry were performed with the PLATON21 pack-
age.
3
3JH-H ) 8.5 Hz, 6H, o-H PPh3), 6.90 (t, JH-H ) 7.3 Hz, 1H,
3
3
Ar), 7.00 (d, JH-H ) 7.3 Hz, 2H, Ar), 7.12 (t, JH-H ) 7.0 Hz,
6H, m-H PPh3), 7.31 (t, JH-H ) 7.3 Hz, 3H, p-H PPh3). 13C
3
NMR (CD2Cl2): δ 38.5 (m, CH2), 107.6 (m, Cquat ArF), 122.8 (s,
3
Ar), 123.6 (vt, Ar), 128.0 (d, JC-P ) 9 Hz, m-C PPh3), 130.4
(s, p-C PPh3), 133.3 (d, 2JC-P ) 9 Hz, o-C PPh3), 135.1 (d, 1JC-P
) 39 Hz, Cquat PPh3), 137.1 (doublet of multiplet, 1JC-F ) 312.4
Hz, ArF), 142.8 (doublet of multiplet, JC-F ) 256.3 Hz, ArF),
1
1
146.3 (t, Ar), 147.3 (doublet of multiplet, JC-F ) 247.5 Hz,
ArF), 149.5 (d, JC-P ) 10 Hz, Cipso, Ar). 31P NMR (CD2Cl2) δ:
2
35.4 (t, 2JP-P ) 29 Hz, PPh3), 36.5 (d, 2JP-P ) 29 Hz, P(C6F5)2),
19F NMR (CD2Cl2, room temperature): δ -164.28 (bs, 4F, m-F
3
(C6F5)), -163.56 (bs, 4F, m-F (C6F5)), -153.30 (t, JF-F ) 20
Hz, 2F, p-F (C6F5)), -152.60 (t, 3JF-F ) 20 Hz, 2F, p-F (C6F5)),
-128,7 (bs, o-F (C6F5)). Anal. Calcd for C50H22ClF20P3Ru: C,
48.74; H, 1.80; P, 7.54. Found: C, 48.56; H, 1.77; P, 7.46.
Acknowledgment. We thank Mrs. Qiao Wu and
Mr. Darryl Morrison of the University of Calgary for
performing the HOESY measurements and NWO/NCF
for use of the supercomputer time on TERAS/ASTER,
SARA (The Netherlands, Project No. SG-032). This work
was supported by the Council for Chemical Sciences
from the Dutch Organization of Scientific Research
(NWO) and Natural Sciences and Engineering Research
Council (NSERC) of Canada (P.A.C.). R.W.A.H. acknowl-
edges financial support from NWO Grant No. 700.53.401.
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Supporting Information Available: CIF file giving X-ray
structural data for complex 4. This material is available free
of charge via the Internet at http://pubs.acs.org.
(20) Sheldrick, G. M. SHELXL-97: Program for Crystal Structure
Refinement; Universita¨t Go¨ttingen, Go¨ttingen, Germany, 1997.
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