Water-soluble 3,7-dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane (dmoPTA) as a polydentate ligand: Synthesis of [RuClCp(PPh3)-μ- dmoPTA-1κP:2κ2N,N′-Co(acac-κ2O, O′)2]·H2O

Article abstract of DOI:10.1021/ic702239w

The dinuclear complex [RuClCp(PPh₃)-μ-dmoPTA-1κP: 2κ²N,N′-Co(acac-κ²O,O′) ₂]·H₂O (2; dmoPTA = 3,7-dimethyl-1,3,7-triaza-5- phosphabicyclo[3.3.1]nonane) has been synthesized by reaction of [RuClCp(HdmoPTA)(PPh₃)](OSO₂CF₃) (1) with Co(acac)₂ in methanol (HdmoPTA = 3,7-H-3,7-dimethyl-1,3,7-triaza-5- phosphabicyclo[3.3.1]nonane). Elemental analysis, IR, NMR, and single-crystal X-ray structure determination have characterized the new complex. This complex is active for the catalytic isomerization of but-1-en-3-ol in acetone better than 1.

Full text of DOI:10.1021/ic702239w

Inorg. Chem. 2008, 47, 2246-2248
Water-Soluble 3,7-Dimethyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane
(dmoPTA) as a Polydentate Ligand: Synthesis of
2
2
[RuClCp(PPh3)-µ-dmoPTA-1KP:2K N,N′-Co(acac-K O,O′)2]·H2O
Adrián Mena-Cruz,† Pablo Lorenzo-Luis,† Antonio Romerosa,*,‡ and Manuel Serrano-Ruiz‡
Área de Química Inorgánica, Facultad de Ciencias, UniVersidad de Almería, Almería, Spain, and
Departamento de Química Inorgánica, Facultad de Química, UniVersidad de La Laguna, La
Laguna, Tenerife, Spain
Received November 14, 2007
The dinuclear complex [RuClCp(PPh3)-µ-dmoPTA-1κP:2κ2N,N′-
Co(acac-κ2O,O′)2]·H2O (2; dmoPTA ) 3,7-dimethyl-1,3,7-triaza-
5-phosphabicyclo[3.3.1]nonane) has been synthesized by reaction
of [RuClCp(HdmoPTA)(PPh3)](OSO2CF3) (1) with Co(acac)2 in
for obtaining a family of phosphines containing amino acids2
and three new PTA derivatives: the dmPTA, dmoPTA, and
HdmoPTA (PTA ) 1,3,5-triaza-7-phosphaadamantane; dmP-
TA ) N,N′-dimethyl-1,3,5-triaza-7-phosphaadamantane;
dmoPTA
)
3, 7-dimethyl-1, 3, 7-triaza-5-
methanol (HdmoPTA
)
3,7-H-3,7-dimethyl-1,3,7-triaza-5-
phosphabicyclo[3.3.1]nonane; HdmoPTA ) 3,7-H-3,7-di-
methyl-1,3,7-triaza-5-phosphabicyclo[3.3.1]nonane).3 These
compounds are easily obtained, being interesting ligands for
obtaining new water-soluble complexes useful as catalysts
in aqueous homogeneous catalysis. As a result of
our initial efforts, the novel complex [RuClCp
(HdmoPTA)(PPh3)](OSO2CF3) (1) was obtained by the
reaction of dmPTA with [RuClCp(PPh3)2]. In complex 1,
the new ligand HdmoPTA is coordinated by the P atom to
the metal.3 Three conclusions could be extracted from the
observed reactivity for HdmoPTA and the analysis of the
crystal structure of 1: (a) the H atom between both CH3-N
atoms can be removed easily using a 0.01 M KOH water
solution at room temperature; (b) the two CH3-N atoms, as
tertiary amines, are capable of coordinating to hard atoms;
(c) the distance between both CH3-N atoms [2.702(12) Å]
is good enough to suppose that through these atoms the
dmoPTA is able to chelate a metal without supporting
significant distortion. Therefore, the dmoPTA could be a
polydentate ligand through the P and CH3-N atoms (Scheme
1). To verify this suspicion, we have first studied the reaction
of [RuClCp(HdmoPTA)(PPh3)](OSO2CF3) (1) with Co(a-
cac)2 (acac ) acetylacetonate) in refluxing methanol (see
below).
phosphabicyclo[3.3.1]nonane). Elemental analysis, IR, NMR, and
single-crystal X-ray structure determination have characterized the
new complex. This complex is active for the catalytic isomerization
of but-1-en-3-ol in acetone better than 1.
Tertiary water-soluble phosphines have been the most
widely used class of hydrosoluble ligands for catalysis in
water because of their neutral donating ability, which can
effectively stabilize the metal center throughout several
catalytic cycles. A variety of hydrosoluble phosphines have
appeared throughout the years, and their catalytic potential
has been investigated.1 Our research group has paid special
attention to the synthesis of new water-soluble phosphines.
We have recently presented the synthetic general procedure
*
To whom correspondence should be addressed. E-mail:
romerosa@ual.es.
†
Universidad de La Laguna.
Universidad de Almería.
‡
(1) (a) Joó, F. Aqueous Organometallic Catalysis; Kluwer: Dordrecht, The
Netherlands, 2001. (b) Cornils, B., Herrmann, W. A., Eds. Aqueous-
Phase Organometallic Catalysis. Concepts and Applications; Wiley-
VCH: Weinheim, Germany, 1998. (c) Horvath, I. T., Joo, F., Eds.
Aqueous Organometallic Chemistry and Catalysis; NATO ASI 3/5;
Kluwer: Dordrecht, The Netherlands, 1995. (d) Sinou, D. Top. Curr.
Chem. 1999, 206, 41. (e) Frost, B. J.; Mebi, C. A. Organometallics
2004, 23, 5317. (f) Darensbourg, D. J.; Ortiz, C. G.; Kamplain, J. W.
Organometallics 2004, 23, 1747. (g) Darensbourg, D. J.; Joó, F.;
Kannisto, M.; Kathó, A.; Reibenspies, J. H.; Daigle, D. J. Inorg. Chem.
1994, 33, 200. (h) Phillips, A. D.; Gonsalvi, L.; Romerosa, A.; Vizza,
F.; Peruzzini, M. Coord. Chem. ReV. 2004, 248, 955. (i) Mohr, F.;
Cerrada, E.; Laguna, M. Organometallics 2006, 25, 644. (j) Mohr,
F.; Sanz, S.; Tiekink, E. R. T.; Laguna, M. Organometallics 2006,
25, 3084. (k) Jordan, J. P.; Grubbs, R. H. Agew. Chem., Int. Ed 2007,
46, 5152–5155. (l) Rossin, A.; Gonsalvi, L.; Phillips, A. D.; Maresca,
O.; Lledós, A.; Peruzzini, M. Organometallics 2007, 26, 3289–3296.
(m) Sanz, S.; Jones, L. A.; Mohr, F.; Laguna, M. Organometallics
2007, 26, 952–957. (n) Mebi, C. A.; Nair, R. P.; Frost, B. J.
Organometallics 2007, 26, 429–438.
Numerous examples of complexes containing the {Co(a-
cac)2} moiety have been development in recent years because
of their actual and potential applications in areas such as
bioinorganic chemistry, medicine, high catalytic activity at
low cost, antiferromagnetism, and electrochromism and
(2) Ciardi, C.; Romerosa, A.; Serrano-Ruiz, M.; Gonsalvi, L.; Peruzzini,
M.; Reginato, G. J. Org. Chem. 2007, 72, 7787.
(3) Mena-Cruz, A.; Lorenzo-Luis, P.; Romerosa, A.; Saoud, M.; Serrano-
Ruiz, M. Inorg. Chem. 2007, 46, 6120.
2246 Inorganic Chemistry, Vol. 47, No. 7, 2008
10.1021/ic702239w CCC: $40.75  2008 American Chemical Society
Published on Web 03/11/2008

COMMUNICATION
Scheme 1
Figure 1. ORTEP diagram of 2. Ellipsoids are shown at 50% probability.
For the sake of clarity, the H atoms were omitted.
to low field with respect to 1. Powder magnetism measure-
ments of 2 between 2 and 300 K (Figure S3 of the Supporting
Information) showed that the values and the shape of the
curve are as expected for isolated octahedral CoII ions with
some trigonal distortions.7 Crystals good enough for X-ray
diffraction were obtained by slow evaporation from an
acetone solution of 2.8 A perspective drawing of its crystal
structure with atom numbering is depicted in Figure 1. The
coordination polyhedron around the Ru atom adopts a highly
distorted pseudooctahedral geometry [P1-Ru1-P2 )
99.04(11)°], similar to that observed for piano-stool com-
plexes of the type [RuCpX(L)(L′)]n+,9 such as 1, recently
published by us.3
as a regulating agent for radical polymerization of poly(vinyl
acetate).4
The reaction of 1 with Co(acac)2 in methanol5 led to the
new bimetallic complex [RuClCp(PPh3)-µ-dmoPTA-1κP:
2κ2N,N′-Co(acac-κ2O,O′)2] · H2O (2), which was first char-
acterized by elemental analysis, IR (Figure S1 of the
Supporting Information), and NMR spectroscopy. The
31P{1H} NMR spectrum in CD3OD is constituted by two
doublets at 52.71 and 51.56 ppm (2JPP ) 41.6 Hz), which
had arisen to a field lower than those found in starting
complex 1 [δ(PPh3) ) 46.00 ppm; δ(HdmoPTA) ) -2.93
ppm], while the coupling constant is practically the same
(2JPP ) 42.72 Hz). That effect could be justified by
considering CoII bonded to dmoPTA through both CH3-N
atoms. As expected, the CoII paramagnetic influence on
dmoPTA [∆δ (2-dmoPTA - 1-HdmoPTA ) -54.49
ppm] is bigger than that on the PPh3 [∆δ (2-PPh3 - 1-PPh3
No significant differences were found in the rest of the
bond distances and angles from those found in similar
cyclopentadienyl RuII complexes.3,9 The monodentate
{RuClCp(PPh3)(dmoPTA-1κP)} entity acts as a bidentate
ligand by its CH3-N atoms toward a CoII atom, which
6
1
) 6.71 ppm]. Similarly, its H and 31C{1H} NMR could
(7) Magnetic susceptibility measurements on polycrystalline samples were
carried out in the temperature range 1.9-300 K by means of a
Quantum Design SQUID magnetometer operating at 10 000 Oe.
Diamagnetic corrections of the constituent atoms were estimated from
Pascal’s constants. Experimental susceptibilities were also corrected
for the magnetization of the sample holder.
only be justified by the CoII paramagnetic effect. An
indubitable assignation of the H NMR signals was not
1
possible (Figure S2 of the Supporting Information), while
the 13C{1H} NMR signals for PPh3 (127.8–136.22 ppm) and
Cp (88.24 ppm) were the only ones clearly assigned. It is
interesting to point out that the Cp signal is shifted 8.9 ppm
(8) The structure was determined by direct methods and refined by least-
squares procedures on F2. (a) Altamore, A.; Cascarano, G.; Giaco-
vazzo, C.; Guagliardi, A.; Moliterni, G.; Burla, M. C.; Polidori, G.;
Camalli, M.; Spagna, R. Sir 97 Package Program; 1997. (b) Sheldrick,
G. M. SHELXL, version 6.14; Bruker-AXS: Madison, WI, 2003.
Crystallographic data were collected at 293(2) K on a Bruker APEX
CCD diffractometer (XDIFRACT service of the University of Almería)
with Mo KR radiation (λ ) 0.710 69 Å). Crystal data for 2 (CCDC
667604): 0.07 × 0.05 × 0.04 mm3, monoclinic P21/c, Z ) 4, a )
12.154(5) Å, b ) 35.492(5) Å, c ) 9.884(5) Å, R ) 90°, V ) 4082(3)
Å3, -14 e h e 13, -35 e k e 41, -11 e l e 11. Of the 6733
measured independent reflections in the θ range 1.75–24.44°, 3414
have I0 > 2σ(I0), R1 ) 0.0810, wR2 ) 0.1468. The function
(4) (a) For example, see: Reeve, T. B.; Cros, J. P.; Gennari, C. Angew.
Chem., Int. Ed. 2006, 45, 2449. (b) Dickie, D. A.; Schatte, G.; Jennings,
M. C. Inorg. Chem. 2006, 45, 1646. (c) Levitin, I. Y.; Yatsimirsky,
A. K.; Volpin, M. E. Organomet. Chem. U.S.S.R. 1990, 3, 442. (d)
Debuigne, A.; Caille, J.-R.; Jéróme, R. Angew. Chem., Int. Ed. 2005,
44, 1101. (e) Rivera, E. F.; Atakan, B.; Kohse-Hoinghaus, K. J. Phys.
IV 2001, 11, Pr3–629. (f) Granquist, C. G. Handbook of Inorganic
Electrochromic Materials; Elsevier: Amsterdam, The Netherlands,
1995.
2
(5) Co(acac)2 (0.0858 g, 0.33 mmol) was introduced into a solution of 1
(0.075 g, 0.0095 mmol) in 6 mL of MeOH. The mixture was first
stirred at room temperature until dissolution of the reactants was
completed and then refluxed for 3.5 h. The solvent was removed until
0.5 mL, and then 5 mL of pentane was added. The obtained pale-
brown precipitated was filtered and washed with water (2 × 5 mL).
The wet powder was recrystallized in EtOH. Yield: 47.7 mg (∼ 55%).
minimized during the refinement was w ) 1/[σ2(Fo ) + (0.0631P)2 +
2
0.0000P], where P ) [(max(Fo ) + 2Fc2)/3]. The H atoms were refined
with isotropic temperature factors. The final Fourier difference maps
showed maximum and minimum height peaks of 1.067 and -0.952
e/Å3.
(9) (a) Romerosa, A.; Campos-Malpartida, T.; Lidrissi, C.; Saoud, M.;
Serrano-Ruiz, M.; Peruzzini, M.; Garrido-Cárdenas, J. A.; García-
Maroto, F. Inorg. Chem. 2006, 46, 1289. (b) Lidrissi, C.; Romerosa,
A.; Saoud, M.; Serrano-Ruiz, M.; Gonsalvi, L.; Peruzzini, M. Angew.
Chem., Int. Ed. 2005, 44, 2568. (c) Romerosa, A.; Saoud, M.; Campos-
Malpartida, T.; Lidrissi, C.; Serrano-Ruiz, M.; Peruzzini, M.; Garrido-
Cárdenas, J. A.; García-Maroto, F. Eur. J. Inorg. Chem. 2007, 2803.
(d) Akbayeva, D. N.; Gonsalvi, L.; Oberhauser, W.; Peruzzini, M.;
Vizza, F.; Brüggeller, P.; Romerosa, A.; Sava, G.; Bergamo, A. Chem.
Commun. 2003, 264. (e) Bolaño, S.; Gonsalvi, L.; Zanobini, F.; Vizza,
F.; Bertolasi, V.; Romerosa, A.; Peruzzini, M. J. Mol. Catal. A 2004,
224, 61.
S25°C,H O < 1 mg/mL. Elem anal. Calcd for C40H52N3ClO5P2RuCo
2
(MW ) 912.25 g/mol): C, 52.66; H, 5.70; N, 4.60. Found: C, 52.42;
H, 5.81; N, 4.47. 13C{1H} NMR (CD3OD): δ (ppm) 88.24 (s, Cp),
127.8–136.22 (m, aromatic, PPh3). 31P{1H} NMR (CD3OD): δ (ppm)
52.71 (d, 2JPP ) 41.6 Hz, PPh3), 51.56 (dd, 2JPP ) 41.6 Hz, dmoPTA).
(6) (a) Bertini, I.; Turano, P.; Vila, A. J. Chem. ReV. 1993, 93, 2833. (b)
Bonadies, J. A.; Kirk, M. L.; Lah, M. S.; Kessissoglou, D. P.; Hatfield,
W. E.; Pecoraro, V. L. Inorg. Chem. 1989, 28, 2037. (c) Bertini, I.;
Luchinat, C. NMR of Paramagnetic Molecules in Biological Systems;
Benjamin-Cumming Publishing Co.: Menlo Park, CA, 1986.
Inorganic Chemistry, Vol. 47, No. 7, 2008 2247

COMMUNICATION
coordination of PTA and its derivatives have been described
up to now.9a,13
Preliminary tests14 on the catalytic activity of 1 and 2 in
the isomerization of enols to enones show that complex 2 is
more active than 1 under similar conditions. A full paper
will address the complete catalytic study in due time.
Therefore, the ligand dmoPTA not only is an interesting
ligand to obtain heterometallic complexes but could provide
a very large variety of new complexes with possible new
and interesting properties. An accurate study on the catalytic
isomerization of enols by this complex as well as the
synthesis of new heterometallic complexes containing the
ligand dmoPTA is now in progress.
Figure 2. View along the c axis of a packing diagram (section) of 2 through
CCp-H· · ·Cl, CPPh -H· · ·Cl, CdmPTA-H· · ·Ow, and CPPh -H· · ·Ow interac-
3
3
tions (broken lines).
Acknowledgment. Funding for this work is provided by
Junta de Andalucía through PAI (Team FQM-317), the
project AQUACHEM (MRTN-CT-2003-503864), the COST
Actions D17 and D29, and the MCYT (Spain) Project
CTQ2006-06552/BQU. We also thank the Consejería de
Educación, Cultura y Deportes (Gobierno Autónomo de
Canarias, Spain), for supporting A.M.-C. We acknowledge
the assistance of the Servicio General de Medidas Magnéticas
of the University of La Laguna for their magnetic measure-
ment facilities.
completes its six-coordination geometry with four O atoms
from two acac molecules. The ligands bonded to the metal
form four stable six-membered chelated rings
[2(Co-O-C3-O)+(Co-N-C-P-C-N)+(Co-N-C-N-C-N)].
The Co atom does not deviate significantly from the mean
equatorial plane (0.0163 Å). Rest of the bond distances found
are in agreement with those reported for carboxylate- and
bpy-containing CoII complexes.10,11 The values for the
dihedralanglesbetweentheequatorialplane(N3-N1-O2-O3)
andthatforthephosphaadamantanebonds(P2-C12-N3-C14)
and (P2-C10-N1-C13) are 89.03(36) and 84.97(35)°,
respectively. Finally, the heterometallic dinuclear units are
interconnected through intermolecular C-H · · · Cl and
N-H · · · Owater interactions (Figure 2; ranging from 2.783 to
2.869 Å and from 2.644 to 2.801 Å, respectively), postulated
in the literature as weak hydrogen bonds.12 It is important
to stress that only three additional examples for P,N
Supporting Information Available: Figures S1-S3. This
material is available free of charge via the Internet at http://
pubs.acs.org. Crystallographic data for 2 can be obtained free of
charge from the CCDC via www.ccdc.cam.ac.uk/data_request/cif
under CCDC 667604.
IC702239W
(13) (a) Frost, B. J.; Bautista, C. M.; Huang, R.; Shearer, J. Inorg. Chem.
2006, 45, 3481. (b) Mohr, F.; Falvello, L. R.; Laguna, M. Eur. J. Inorg.
Chem. 2006, 3152.
(10) Ruiz-Pérez, C.; Lorenzo-Luis, P.; Hernández-Molina, M.; Milagros
Laz, M.; Delgado, S. F.; Gili, P.; Julve, M. Eur. J. Inorg. Chem. 2004,
19, 3873.
(14) Into a NMR tube was introduced 1 (2.6 mg, 0.032 mmol) or 2 (2.9
mg, 0.032 mmol), 10 equiv of the substrate but-1-en-3-ol (2.8 µL,
0.032 mmol), and 0.6 mL of acetone-d6. The reaction was checked at
room temperature by 1H NMR. At 65 °C, complex 2 catalyzed the
isomerization of the substrate to give 3-butanone in 2.5 h, while 1 is
not active. The addition of 2.5% water to the reaction increased the
activity of 1, but the reactivity of 2 was even lower.
(11) (a) Chang-Yan, S.; Lin-Pei, J. Polyhedron 2006, 25, 1327. (b) Bao-
Quing, M.; Song, G.; Yi, T.; Guang-Xian, X. Polyhedron 2001, 20,
1255.
(12) (a) Steiner, T. Angew. Chem., Int. Ed. 2002, 41, 48. (b) Phillips, A. D.;
Bolaño, S.; Bosquiain, S. S.; Jean-Claude, D.; Malacea, R.; Peruzzini,
M.; Poli, R.; Gonsalvi, L. Organometallics 2006, 25, 2189.
2248 Inorganic Chemistry, Vol. 47, No. 7, 2008