Arene-ruthenium(II) complexes containing amino-phosphine ligands as catalysts for nitrile hydration reactions

Article abstract of DOI:10.1021/om1006227

Three different series of novel mononuclear arene-ruthenium(II) complexes containing amino-phosphine ligands, namely, [RuCl₂{κ ¹(P)-2-Ph₂PC₆H₄CH ₂NHR}(η⁶-arene)], [RuCl₂{κ ¹(P)-3-Ph₂PC₆H₄CH ₂NHR}(η⁶-arene)], and [RuCl₂{κ ¹(P)-4-Ph₂PC₆H₄CH ₂NHR}(η⁶-arene)] (arene = C₆H₆, p-cymene, 1,3,5-C₆H₃Me₃, C₆Me ₆; R = ⁱPr, ^tBu; all combinations), have been synthesized and fully characterized. These readily accessible species are efficient catalysts for the selective hydration of organonitriles into amides under challenging reaction conditions, i.e., pure aqueous medium in the absence of any cocatalyst, being much more active than their corresponding nonfunctionalized triphenylphosphine counterparts [RuCl₂(PPh ₃)(η⁶-arene)]. The results obtained in this study indicate that the (amino-phosphine)ruthenium(II) complexes operate through a "bifunctional catalysis" mechanism in which the ruthenium center acts as a Lewis acid, activating the nitrile molecule, and the P-donor ligand acts as a Brnsted base, the pendant amino group generating the real nucleophile of the hydration process, i.e., the OH^- group.

Full text of DOI:10.1021/om1006227

Organometallics 2010, 29, 3955–3965 3955
DOI: 10.1021/om1006227
Arene-Ruthenium(II) Complexes Containing Amino-Phosphine
Ligands as Catalysts for Nitrile Hydration Reactions
ꢀ
Rocıo Garcıa-Alvarez, Josefina Dıez, Pascale Crochet,* and Victorio Cadierno*
´
ꢀ
ꢀ
´
ꢀ
Departamento de Quımica Organica e Inorganica, Instituto Universitario de Quımica Organometalica
´
8, E-33006 Oviedo, Spain
ꢀ
´
“Enrique Moles” (Unidad Asociada al CSIC), Facultad de Quımica, Universidad de Oviedo, Julian Claverıa
Received June 29, 2010
Three different series of novel mononuclear arene-ruthenium(II) complexes containing amino-
phosphine ligands, namely, [RuCl2{κ1(P)-2-Ph2PC6H4CH2NHR}(η6-arene)], [RuCl2{κ1(P)-3-Ph2-
PC6H4CH2NHR}(η6-arene)], and [RuCl2{κ1(P)-4-Ph2PC6H4CH2NHR}(η6-arene)] (arene = C6H6,
p-cymene, 1,3,5-C6H3Me3, C6Me6; R = iPr, tBu; all combinations), have been synthesized and fully
characterized. These readily accessible species are efficient catalysts for the selective hydration of
organonitriles into amides under challenging reaction conditions, i.e., pure aqueous medium in the
absence of any cocatalyst, being much more active than their corresponding nonfunctionalized tri-
phenylphosphine counterparts [RuCl2(PPh3)(η6-arene)]. The results obtained in this study indicate
that the (amino-phosphine)ruthenium(II) complexes operate through a “bifunctional catalysis“ mec-
hanism in which the ruthenium center acts as a Lewis acid, activating the nitrile molecule, and the
P-donor ligand acts as a Brønsted base, the pendant amino group generating the real nucleophile of
the hydration process, i.e., the OH- group.
Introduction
into the corresponding carboxylic acids, a kinetically favored
reaction compared to the hydration one (see Scheme 1).1,4
Although under acidic conditions it is possible to stop the
process at the amide stage, in these cases it is necessary to
control carefully the temperature and stoichiometry em-
ployed in order to avoid the formation of polymeric side
products.5 It is also important to note that, from an indus-
trial perspective, the final neutralization step required in
either the acid- or base-catalyzed reactions leads to extensive
salt formation with inconvenient product contamination and
pollution effects.
To circumvent all these limitations, several protocols using
enzymes,2,6 heterogeneous catalysts,7 and transition-metal
complexes8 have been developed. In particular, a large
variety of homogeneous catalysts highly selective toward
amide formation have been described,9 with Murahashi’s
ruthenium dihydride [RuH2(PPh3)4],10 Parkins’s platinum
hydride [PtH(PMe2OH){(PMe2O)2H}],11 the acetylacetonate
complex cis-[Ru(acac)2(PPh2py)2],12 and the Rh(I)-based sys-
tem [{Rh(μ-OMe)(cod)}2]/PCy3 (cod = 1,5-cyclooctadiene),9h
showing remarkable activities under mild conditions. In
Hydration of nitriles is one of the most appealing routes
presently available for the large-scale production of amides,
which are versatile synthetic intermediates used in the manu-
facture of several pharmacological products, polymers,
detergents, lubricants, and drug stabilizers.1 As an example,
hydration of acrylonitrile produces annually more than 2 ꢀ
105 tons of acrylamide, representing the main industrial
route for this chemical.2,3 Traditionally, these hydration pro-
cesses have been catalyzed by strong acids and bases under
harsh conditions, methods that are not compatible with
many sensitive functional groups.4 In addition, the base-
catalyzed reactions usually cause overhydrolysis of the amides
*To whom correspondence should be addressed. E-mail: crochetpascale@
uniovi.es (P.C.); vcm@uniovi.es (V.C.).
(1) See, for example: (a) The Chemistry of Amides; Zabicky, J., Ed.;
Wiley: New York, 1970. (b) The Amide Linkage: Structural Significance in
Chemistry, Biochemistry and Materials Science; Greenberg, A.; Brene-
man, C. M.; Liebman, J. F., Eds.; Wiley: New York, 2000. (c) Polyesters and
Polyamides; Deopura, B. L.; Gupta, B.; Joshi, M.; Alagirusami, R., Eds.;
CRC Press: Boca Raton, 2008. (d) Johansson, I. In Kirk-Othmer Encyclo-
pedia of Chemical Technology; Wiley: New York, 2004; Vol. 2, pp
442-463.
(2) Yamada, H.; Kobayashi, M. Biosci., Biotechnol., Biochem. 1996,
60, 1391.
(5) See, for example: (a) Edward, J. T.; Meacock, S. C. R. J. Chem.
Soc. 1957, 2000. (b) Steynberg, P. J.; Denga, Z.; Steyn, R.; Bezuidenhout,
B. C.; Stark, N. L. Int. Pat. Appl. WO 0026178, 2000.
(3) Hydration of 3-cyanopyridine and adiponitrile into nicotinamide
and 5-cyanovaleramide, respectively, are other relevant examples of the
industrial applications of this process. See: van Pelt, S.; van Rantwijk,
F.; Sheldon, R. A. In Focus in Catalysis Applications (supplement to
Chim. Oggi 2008, 26); pp 2-4.
(4) See, for example: (a) Bailey, P. D.; Mills, T. J.; Pettecrew, R.;
Price, R. A. In Comprehensive Organic Functional Group Transforma-
tions II; Katritzky, A. R.; Taylor, R. J. K., Eds.; Elsevier: Oxford, 2005; Vol.
5, pp 201-294. (b) Methoden Org. Chem. (Houben Weyl); Dopp, D.;
Dopp, H., Eds.; Thieme Verlag: Stuttgart, 1985; Vol. E5 (2), pp 1024-1031.
(6) For selected reviews covering the use of enzymes in catalytic nitrile
hydrations, see: (a) Kobayashi, M.; Shimizu, S. Curr. Opin. Chem. Biol.
2000, 4, 95. (b) Endo, I.; Nojori, M.; Tsujimura, M.; Nakasako, M.;
Nagashima, S.; Yohda, M.; Odaka, M. J. Inorg. Biochem. 2001, 83, 247.
ꢀ
ꢀ
(c) Mylerova, V.; Martínkova, L. Curr. Org. Chem. 2003, 7, 1279.
(d) Kovacs, J. A. Chem. Rev. 2004, 104, 825. (e) De Santis, G.; Di Cosimo,
R. In Biocatalysis for the Pharmaceutical Industry: Discovery, Develop-
ment and Manufacturing; Tao, J.; Lin, G.-Q.; Liese, A., Eds.; Wiley-VCH:
Weinheim, 2009; pp 153-181.
r
2010 American Chemical Society
Published on Web 08/03/2010
pubs.acs.org/Organometallics

ꢀ
´
Garcıa-Alvarez et al.
3956 Organometallics, Vol. 29, No. 17, 2010
Scheme 1. Nitrile Hydration and Amide Hydrolysis Reactions
Figure 1. Cooperative effect of the ligand.
addition to these examples, all operating in organic media,
some metal complexes able to promote selective nitrile hyd-
rations directly in water have also been disclosed, mainly
thanks to the use of hydrosoluble ligands or surfactants.13
From a mechanistic point of view, although different re-
action pathways have been proposed for these metal-cata-
lyzed transformations, coordination of the nitrile to the
metal is a common prerequisite for all of them.8-13 In this
way, the CtN unit becomes more electrophilic and suscep-
tible to nucleophilic attack by water (or the hydroxyl group if
basic conditions are used), thus improving the kinetics of the
Figure 2. Structure of the (η6-arene)-Ru(II) complexes synthe-
sized in this work.
(7) See, for example: (a) Rao, C. G. Synth. Commun. 1982, 12, 177.
(b) Liu, K.-T.; Shih, M.-H.; Huang, H.-W.; Hu, C.-J. Synthesis 1988, 715.
(c) Breuilles, P.; Leclerc, R.; Uguen, D. Tetrahedron Lett. 1994, 35, 1401.
(d) Wilgus, C. P.; Downing, S.; Molitor, E.; Bains, S.; Pagni, R. M.; Kabalka,
G. W. Tetrahedron Lett. 1995, 36, 3469. (e) Sebti, S.; Rhihil, A.; Saber, A.;
Hanafi, N. Tetrahedron Lett. 1996, 37, 6555. (f) Mori, K.; Yamaguchi, K.;
Mizugaki, T.; Ebitani, K.; Kaneda, K. Chem. Commun. 2001, 461. (g) Solhy,
A.; Smahi, A.; El Badaoui, H.; Elaabar, B.; Amoukal, A.; Tikad, A.; Sebti, S.;
Macquarrie, D. J. Tetrahedron Lett. 2003, 44, 4031. (h) Yamaguchi, K.;
Matsushita, M.; Mizuno, N. Angew. Chem., Int. Ed. 2004, 43, 1576. (i) Bazi,
F.; El Badaoui, H.; Tamani, S.; Sokori, S.; Solhy, A.; Macquarrie, D. J.; Sebti,
S. Appl. Catal. A: Gen. 2006, 301, 211. (j) Polshettiwar, V.; Varma, R. S.
Chem.—Eur. J. 2009, 15, 1582. (k) Mitsudome, T.; Mikami, Y.; Mori, H.;
Arita, S.; Mizugaki, T.; Jitsukawa, K.; Kaneda, K. Chem. Commun. 2009,
3258. (l) Ishizuka, A.; Nakazaki, Y.; Oshiki, T. Chem. Lett. 2009, 38, 360.
(8) For reviews covering the field of metal-mediated and metal-
catalyzed nitrile hydration, see: (a) Kukushkin, V. Y.; Pombeiro,
A. J. L. Inorg. Chim. Acta 2005, 358, 1. (b) Bokach, N. A.; Kukushkin,
V. Y. Russ. Chem. Rev. 2005, 74, 153. (c) Kukushkin, V. Y.; Pombeiro,
A. J. L. Chem. Rev. 2002, 102, 1771.
hydration process versus the hydrolysis (see Scheme 1).
Recent work has also suggested that this nucleophilic addi-
tion step can be facilitated by the presence of functionalized
ligands able to activate the water molecule via hydrogen
bonding (see Figure 1).9m,12,13a,g,i Such a cooperative effect
of the ligand represents a new example of the so-called
“bifunctional catalysis”; that is, the metal ion acts as a Lewis
acid and the ligand as a Lewis base, a concept largely ex-
ploited in homogeneous catalysis during the last years.14
With this mechanistic idea in mind, and continuing with
our interest in this key catalytic transformation,13g,i we
wondered about the potential of (η6-arene)-Ru(II) com-
plexes A-C, containing readily accessible amino-phosphine
ligands (Figure 2), as catalysts for the selective hydration of
nitrile to amides.15 We reasoned that, while the presence of a
pendant amino group on these P-donor ligands would ensure
the activation of the water molecule via hydrogen bonding,
the exact location of the amino substituent on the aromatic
ring should drastically affect the efficiency of these catalysts,
conditioning the effective approach of the activated hydrogen-
bonded water molecule to the coordinated nitrile. In this
way, very useful information on the real operativity of a
bifunctional catalysis mechanism could be easily gained
experimentally. Results from this study are presented herein.
(9) For recent examples, see: (a) Oshiki, T.; Hyodo, I.; Ishizuka, A.
ꢀ
J. Synth. Org. Chem. Jpn. 2010, 68, 41. (b) Crisostomo, C.; Crestani, M. G.;
ꢀ
García, J. J. Inorg. Chim. Acta 2010, 363, 1092. (c) Ramon, R. S.; Marion,
N.; Nolan, S. P. Chem.—Eur. J. 2009, 15, 8695. (d) Crestani, M. G.; García,
J. J. J. Mol. Catal. A: Chem. 2009, 299, 26. (e) Mola, J.; Pujol, D.;
Rodríguez, M.; Romero, I.; Sala, X.; Katz, N.; Parella, T.; Benet-Buchholz,
J.; Fontrodona, X.; Llobet, A. Aust. J. Chem. 2009, 62, 1675. (f) Crestani,
M. G.; Steffen, A.; Kenwright, A. M.; Batsanov, A. S.; Howard, J. A. K.;
ꢀ
Marder, T. B. Organometallics 2009, 28, 2904. (g) Martín, M.; Horvath, H.;
ꢀ
ꢀ
Sola, E.; Katho, A.; Joo, F. Organometallics 2009, 28, 561. (h) Goto, A.;
Endo, K.; Saito, S. Angew. Chem., Int. Ed. 2008, 47, 3607. (i) Leung, C. W.;
Zheng, W.; Zhou, Z.; Lin, Z.; Lau, C. P. Organometallics 2008, 27, 4957.
(j) Yi, C. S.; Zeczycki, T. N.; Lindeman, S. V. Organometallics 2008, 27,
2030. (k) Thallaj, N. K.; Przybilla, J.; Welter, R.; Mandon, D. J. Am. Chem.
ꢀ
Soc. 2008, 130, 2414. (l) Crisostomo, C.; Crestani, M. G.; García, J. J.
ꢁ
J. Mol. Catal. A: Chem. 2007, 266, 139. (m) Smejkal, T.; Breit, B.
Results and Discussion
ꢀ
Organometallics 2007, 26, 2461. (n) Crestani, M. G.; Arevalo, A.; García,
J. J. Adv. Synth. Catal. 2006, 348, 732.
(10) (a) Murahashi, S.-I.; Sasao, S.; Saito, E.; Naota, T. J. Org. Chem.
1992, 57, 2521. (b) Murahashi, S.-I.; Sasao, S.; Saito, E.; Naota, T. Tetra-
hedron 1993, 49, 8805. (c) Murahashi, S.-I.; Takaya, H. Acc. Chem. Res.
2000, 33, 225.
(11) (a) Ghaffar, T.; Parkins, A. W. Tetrahedron Lett. 1995, 36, 8657.
(b) Akisanya, J.; Parkins, A. W.; Steed, J. W. Org. Process Res. Dev. 1998, 2,
274. (c) Ghaffar, T.; Parkins, A. W. J. Mol. Catal. A: Chem. 2000, 160, 249.
(d) Jiang, X.-B.; Minnaard, A. J.; Feringa, B. L.; de Vries, J. G. J. Org. Chem.
2004, 69, 2327.
(12) Oshiki, T.; Yamashita, H.; Sawada, K.; Utsunomiya, M.;
Takahashi, K.; Takai, K. Organometallics 2005, 24, 6287.
(13) See, for example: (a) Chin, C. S.; Kim, S. Y.; Joo, K.-S.; Won,
G.; Chong, D. Bull. Korean Chem. Soc. 1999, 20, 535. (b) Djoman, M. C.
K.-B.; Ajjou, A. N. Tetrahedron Lett. 2000, 41, 4845. (c) Kopylovich,
M. N.; Kakushkin, V. Y.; Haukka, M.; Fraꢀusto da Silva, J. J. R.; Pombeiro,
A. J. L. Inorg. Chem. 2002, 41, 4798. (d) Breno, K. L.; Pluth, M. D.; Tyler,
D. R. Organometallics 2003, 22, 1203. (e) Breno, K. L.; Pluth, M. D.;
Landorf, C. W.; Tyler, D. R. Organometallics 2004, 23, 1738. (f) Ahmed,
T. J.; Zakharov, L. N.; Tyler, D. R. Organometallics 2007, 26, 5179.
(g) Cadierno, V.; Francos, J.; Gimeno, J. Chem.—Eur. J. 2008, 14, 6601.
(h) Cavarzan, A.; Scarso, A.; Struckul, G. Green Chem. 2010, 12, 790.
(i) Cadierno, V.; Díez, J.; Francos, J.; Gimeno, J. Chem.-Eur. J. 2010, in
press (DOI: 10.1002/chem.201001152).
Synthesis of the Amino-phosphine Ligands. Amino-phos-
phine ligands 7-9a,b have been synthesized following classical
(14) The transfer hydrogenation processes through an outer-sphere
mechanism, described by Noyori and co-workers, and the selective
hydration of alkynes to aldehydes (anti-Markovnikov addition), devel-
oped by Grotjahn’s group, are probably the most illustrative and
successful examples of this concept. See, for example: (a) Noyori, R.;
Yamakawa, M.; Hashiguchi, S. J. Org. Chem. 2001, 66, 7931. (b) Noyori,
R.; Ohkuma, T. Angew. Chem., Int. Ed. 2001, 40, 40. (c) Grotjahn, D. B.
Chem.—Eur. J. 2005, 11, 7146. (d) Borovik, A. S. Acc. Chem. Res. 2005,
38, 54. (e) Ikariya, T.; Murata, K.; Noyori, R. Org. Biomol. Chem. 2006, 4,
393. (f) Ikariya, T.; Blacker, A. J. Acc. Chem. Res. 2007, 40, 1300.
(g) Grotjahn, D. B. Dalton Trans. 2008, 6497. (h) Grotjahn, D. B. Pure
Appl. Chem. 2010, 82, 635.
(15) The effectiveness of arene-ruthenium(II) complexes in nitrile
hydration reactions has been largely demonstrated. See refs 13g, 13h,
and: (a) Ashraf, S. M.; Kandioller, W.; Mendoza-Ferri, M.-G.; Nazarov,
A. A.; Hartinger, C. G.; Keppler, B. K. Chem. Biodiversity 2008, 5,
2060. (b) Ashraf, S. M.; Berger, I.; Nazarov, A. A.; Hartinger, C. G.;
Koroteev, M. P.; Nifant'ev, E. E.; Keppler, B. K. Chem. Biodiversity 2008,
5, 1640.

Article
Organometallics, Vol. 29, No. 17, 2010 3957
Scheme 2. General Procedure for the Preparation of Amino-phosphine Ligands 7-9a,b
Scheme 3. Synthesis of the Mononuclear (η6-Arene)ruthenium(II) Complexes 11aa-13db
methodologies (see Scheme 2),16 based on the condensation of
pylamine or tert-butylamine. In this way, the corresponding
phosphine-substituted Schiff bases 4-6a,b were quantitatively
formed and subjected to reduction of the CdN bond by means
known (formylphenyl)diphenylphosphines 1-317 with isopro-
(16) (a) Ghilardi, C. A.; Midollini, S.; Moneti, S.; Orlandini, A.;
Scapacci, G. J. Chem. Soc., Dalton Trans. 1992, 3371. (b) Nikitidis, A.;
Andersson, C. Phosphorus, Sulfur Silicon 1993, 78, 141. (c) Antonaroli, S.;
Crociani, B. J. Organomet. Chem. 1998, 560, 137. (d) Crochet, P.; Gimeno,
J.; García-Granda, S.; Borge, J. Organometallics 2001, 20, 4369. (e) Crochet,
P.; Gimeno, J.; Borge, J.; García-Granda, S. New J. Chem. 2003, 27, 414.
(17) (a) Schiemenz, G. P.; Kaack, H. Justus Liebigs Ann. Chem. 1973,
9, 1480. (b) Schiemenz, G. P.; Kaack, H. Justus Liebigs Ann. Chem. 1973, 9,
1494. (c) Hoots, J. E.; Rauchfuss, T. B.; Wrobleski, D. A. Inorg. Synth. 1982,
21, 175. (d) Sun, Y.; Ahmed, M.; Jackstell, R.; Beller, M.; Thiel, W. R.
Organometallics 2004, 23, 5260.

ꢀ
Garcıa-Alvarez et al.
´
3958 Organometallics, Vol. 29, No. 17, 2010
of NaBH4/MeOH, thus affording the desired amino-phos-
phines 7-9a,b as air-stable, pale yellow oils in 62-89% yield.
Characterization of the novel compounds 3-Ph2PC6H4CHdNR
(5a,b), 4-Ph2PC6H4CHdNR (6a,b), 3-Ph2PC6H4CH2NHR
(8a,b), and 4-Ph2PC6H4CH2NHR (9a,b) was straightforward
following their analytical and spectroscopic data (details are
given in the Experimental Section). Significant features are (i)
(31P{1H} NMR) the presence of a singlet signal at ca. -5 ppm,
(ii) (1H NMR) the appearance of singlet or broad resonances
at ca. 8 (5-6a,b) and 4 ppm (8-9a,b), respectively, attributed
to the iminic CHdN and methylenic CH2N protons, and (iii)
(13C{1H} NMR) the presence of characteristic singlet signals at
ca. 155 (5-6a,b) and 51 (8-9a,b) ppm for the iminic and
methylenic carbons, respectively.
Synthesis of the Arene-ruthenium(II) Complexes. The abi-
lity of dimers [{RuCl(μ-Cl)(η6-arene)}2] to form mononuc-
lear ruthenium(II) species of general composition [RuCl2(η6-
arene)L] (L = 2e- donor ligand) via cleavage of the chloride
bridges is well known.18 In accord, we have found that the re-
action of [{RuCl(μ-Cl)(η6-arene)}2] (arene = C6H6 (10a),19
p-cymene (10b),20 1,3,5-C6H3Me3 (10c),21 C6Me6 (10d)20)
with 2.4 equiv of the amino-phosphine ligands 7-9a,b, in
tetrahydrofuran at room temperature, leads to the selective
formation of the novel mononuclear Ru(II) derivatives
11aa-13db (see Scheme 3).
Figure 3. ORTEP-type view of the structure of complex 11bb
3
HCl showing the crystallographic labeling scheme. Hydrogen
atoms, except those on N(1), have been omitted for clarity.
Thermal ellipsoids are drawn at the 10% probability level.
˚
Selected bond distances (A) and angles (deg): Ru-C* =
1.7179(2); Ru-Cl(1) = 2.4025(8); Ru-Cl(2) = 2.4061(7); Ru-
P(1) = 2.3743(7); C(29)-N(1) = 1.489(4); N(1)-C(30) = 1.530-
(3); C*-Ru-Cl(1) = 124.09(2); C*-Ru-Cl(2) = 126.21(2);
C*-Ru-P(1) = 128.579(18); Cl(1)-Ru-Cl(2) = 85.42(3);
Cl(1)-Ru-P(1) = 89.61(2); Cl(2)-Ru-P(1) = 90.11(2); C(11)-
P(1)-C(17) = 97.88(12); C(11)-P(1)-C(23) = 103.38(12);
C(11)-P(1)-Ru(1) = 116.74(10); C(17)-P(1)-C(23) =
105.49(12); C(17)-P(1)-Ru(1) = 120.82(9); C(23)-P(1)-
Ru(1) = 110.46(8); C(28)-C(29)-N(1) = 113.5(2); C(29)-
N(1)-C(30) = 117.1(3). C* denotes the centroid of the p-cymene
ring (C(1), C(2), C(3), C(4), C(5), and C(6)).
Complexes 11aa-13db, isolated as air-stable orange solids
in 62-89% yield, are soluble in polar solvents, such as
dichloromethane, chloroform, THF, alcohols, and even
water (ca. 1 mg/mL), and insoluble in n-alkanes and diethyl
ether. The formulation proposed for these species is based on
analytical data, as well as IR and multinuclear NMR
(13bb) could be unequivocally confirmed by means of X-ray
diffraction methods. Single crystals suitable for X-ray analy-
sis were obtained by slow diffusion of n-pentane into satu-
rated solutions of these compounds in dichloromethane.
ORTEP views of the molecules, along with selected structural
parameters, are shown in Figures 3-5. The unexpected pro-
tonation of the amino group of 11bb by traces of HCl present
in dichloromethane occurred during crystallization, and
consequently the structure of the corresponding ammonium
1
(31P{1H}, H, and 13C{1H}) spectroscopy (details are given
in the Experimental Section). In particular, the 31P{1H}
NMR spectra of all these derivatives exhibit a singlet reso-
nance (δ 23.7-33.4 ppm) strongly deshielded with respect to
that of the corresponding free amino-phosphine (Δδ =
29-39 ppm), thus supporting the selective P-coordination
1
of the ligands to ruthenium. Their H and 13C{1H} NMR
spectra are also consistent with the proposed structures,
showing the expected resonances for the corresponding
amino-phosphine and η6-coordinated arene groups. At this
point, we must note that, although the N-H proton of the
amino-phosphine ligands was not detected in any case by 1H
NMR spectroscopy, the presence of this group was con-
firmed by the appearance of a characteristic ν(N-H) absorp-
tion band at 3174-3317 cm-1 in the IR spectra.
Moreover, the structure of the p-cymene complexes
[RuCl2{κ1(P)-2-Ph2PC6H4CH2NHtBu}(η6-p-cymene)] (11bb),
[RuCl2{κ1(P)-3-Ph2PC6H4CH2NHtBu}(η6-p-cymene)] (12bb),
and [RuCl2{κ1(P)-4-Ph2PC6H4CH2NHtBu}(η6-p-cymene)]
t
salt [RuCl2{κ1(P)-2-Ph2PC6H4CH2NH2 Bu}(η6-p-cymene)]-
[Cl] (11bb HCl) was obtained (Figure 3). The three mole-
3
cules exhibit an usual pseudooctahedral three-legged piano-
stool geometry around the metal with values of the inter-
ligand angles Cl(1)-Ru-P(1), Cl(2)-Ru-P(1), and Cl(1)-
Ru-Cl(2), and those between the centroid of the p-cymene
ring C* and the legs, typical of a pseudo-octahedron. The ob-
served N(1)-C(29) and N(1)-C(30) bond distances (1.446(5)-
˚
1.530(3) A) fall also within the expected range for a nitrogen-
carbon (sp3) single bond.22
Complexes 11aa-13db were further studied by means of
cyclic voltammetry (CV). Two independent electrochemical
processes were in all cases observed (representative cyclic
voltammograms are shown in Figure 6). The first oxidation
wave observed in the voltammograms, which corresponds to
the oxidation of the amino group,23 is irreversible and dis-
appears after successive scans, while the second one is rever-
sible, or quasi-reversible, and corresponds to the Ru2þ/Ru3þ
(18) For reviews on the chemistry of [{RuCl(μ-Cl)(η6-arene)}2] di-
mers see: (a) Le Bozec, H.; Touchard, D.; Dixneuf, P. H. Adv. Organo-
met. Chem. 1989, 29, 163. (b) Bennett, M. A. In Comprehensive Organo-
metallic Chemistry II; Abel, E. W.; Stone, F. G. A.; Wilkinson, G., Eds.;
Pergamon Press: Oxford, 1995; Vol. 7, pp 549-602. (c) Bennett, M. A.
Coord. Chem. Rev. 1997, 166, 225. (d) Pigge, F. C.; Coniglio, J. J. Curr.
Org. Chem. 2001, 5, 757. (e) K€undig, E. P. Top. Organomet. Chem. 2004, 7,
3. (f) Gimeno, J.; Cadierno, V.; Crochet, P. In Comprehensive Organome-
tallic Chemistry III; Crabtree, R. H.; Mingos, D. M. P., Eds.; Elsevier:
Oxford, 2007; Vol. 6, pp 465-550. (g) Therrien, B. Coord. Chem. Rev.
2009, 253, 493.
(19) Bennett, M. A.; Smith, A. K. J. Chem. Soc., Dalton Trans. 1974,
233.
(20) Bennett, M. A.; Huang, T.-N.; Matheson, T. W.; Smith, A. K.
Inorg. Synth. 1982, 21, 74.
(21) Hull, J. W.; Gladfelter, W. L. Organometallics 1984, 3, 605.
(22) See for example: (a) Allen, F. H.; Kennard, O.; Watson, D. G.;
Brammer, L.; Orpen, A. G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2
1987, S1. (b) Allen, F. H.; Watson, D. G.; Brammer, L.; Orpen, A. G.; Taylor,
R. In International Tables for X-Ray Crystallography; Prince, E., Ed.;
Kluwer Academic Publishers: Dordrecht, The Netherlands, 2004; Vol. C,
p 790.

Article
Organometallics, Vol. 29, No. 17, 2010 3959
Figure 5. ORTEP-type view of the structure of complex 13bb
showing the crystallographic labeling scheme. Hydrogen atoms,
except that on N(1), have been omitted for clarity. Thermal
ellipsoids are drawn at the 10% probability level. Selected bond
Figure 4. ORTEP-type view of the structure of complex 12bb
showing the crystallographic labeling scheme. Hydrogen atoms,
except that on N(1), have been omitted for clarity. Thermal
ellipsoids are drawn at the 10% probability level. Selected bond
˚
distances (A) and angles (deg): Ru-C* =1.7235(2); Ru-Cl(1) =
2.4061(7); Ru-Cl(2) = 2.4236(7); Ru-P(1) = 2.3606(7);
C(29)-N(1) = 1.446(5); N(1)-C(30) = 1.479(5); C*-Ru-
Cl(1) = 124.87(2); C*-Ru-Cl(2) = 127.65(2); C*-Ru-P(1) =
128.800(18); Cl(1)-Ru-Cl(2) = 87.67(3); Cl(1)-Ru-P(1) =
85.89(3); Cl(2)-Ru-P(1) = 88.36(2); C(11)-P(1)-C(17) =
101.87(13); C(11)-P(1)-C(23) = 101.41(13); C(11)-P(1)-
Ru(1) = 121.86(9); C(17)-P(1)-C(23) = 105.92(13); C(17)-
P(1)-Ru(1) = 108.53(10); C(23)-P(1)-Ru(1) = 115.48(9);
C(26)-C(29)-N(1) = 115.0(3); C(29)-N(1)-C(30) = 117.8(3).
C* denotes the centroid of the p-cymene ring (C(1), C(2), C(3),
C(4), C(5), and C(6)).
˚
distances (A) andangles(deg):Ru-C* = 1.7114(2); Ru-Cl(1) =
2.4090(7); Ru-Cl(2) = 2.4232(7); Ru-P(1) = 2.3743(7);
C(29)-N(1) = 1.448(7); N(1)-C(30) = 1.500(7); C*-Ru-
Cl(1) = 124.72(2); C*-Ru-Cl(2) = 126.31(2); C*-Ru-P(1) =
127.945(19); Cl(1)-Ru-Cl(2) = 88.63(3); Cl(1)-Ru-P(1) =
86.39(2); Cl(2)-Ru-P(1) = 90.27(3); C(11)-P(1)-C(17) =
104.18(15); C(11)-P(1)-C(23) = 101.64(14); C(11)-P(1)-
Ru(1) = 120.08(10); C(17)-P(1)-C(23) = 104.55(15); C(17)-
P(1)-Ru(1) = 107.76(11); C(23)-P(1)-Ru(1) = 116.97(10);
C(27)-C(29)-N(1) = 114.3(4); C(29)-N(1)-C(30) = 116.2(5).
C* denotes the centroid of the p-cymene ring (C(1), C(2), C(3),
C(4), C(5), and C(6)).
complexes.25 These observations are also consistent with
theoretical studies that indicate that the HOMO energy level
decreases when substituting Me by H in an arene-metal
complex.26 It is also worthy of note that the exact location of
the CH2NHR substituent on the aromatic ring of the P-donor
ligands exerts some influence on the formal potentials of these
complexes, those derived from the para-substituted phos-
phines being, in general, more easily oxidized than their meta-
redox system. Formal potentials (E°0) of the latter, given
versus the [Cp2Fe]/[Cp2Fe]þ redox couple,24 are collected in
Table 1. In complete accord with the increasing electron-
releasing properties of the arene ring, within the three series
of complexes studied, E°0 values decrease in the sequence C6H6 >
p-cymene ≈ 1,3,5-C6H3Me3 > C6Me6. Similar trends have
been previously reported for related (η6-arene)ruthenium(II)
and ortho-substituted counterparts (in the order E°0para
<
E°0meta < E°0ortho).
(23) Related irreversible oxidations were observed when cyclic vol-
tammograms of N-isopropylbenzylamine (Epa = 1.72 V) and N-benzyl-
tert-butylamine (Epa = 1.81 V) were run under identical experimental
conditions.
(24) (a) Gritzner, G.; Kuta, J. Pure Appl. Chem. 1984, 56, 461.
(b) Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 877.
Catalytic Hydration of Nitriles in Aqueous Medium. The
catalytic potential of the novel (η6-arene)ruthenium(II) com-
plexes 11aa-13bd was then evaluated using the hydration of
benzonitrile into benzamide as model reaction. In a typical
experiment, the ruthenium precursor (5 mol % of Ru) was
added to a 0.33 M aqueous solution of benzonitrile and the
mixture heated in an oil bath at 100 °C. The course of the
reaction was monitored by regular sampling and analysis by
gas chromatography (GC). The results obtained are sum-
marized in Table 2.
All complexes synthesized proved to be active catalysts in
this transformation, providing benzamide as the unique
reaction product (benzoic acid was not detected by GC in
the crude reaction mixtures) in 43-99% GC yield after 24 h
of heating (entries 1-24). Among them, complexes [RuCl2-
{κ1(P)-2-Ph2PC6H4CH2NHtBu}(η6-C6Me6)] (11db), [RuCl2-
{κ1(P)-3-Ph2PC6H4CH2NHtBu}(η6-1,3,5-C6H3Me3)] (12cb),
and [RuCl2{κ1(P)-4-Ph2PC6H4CH2NHiPr}(η6-p-cymene)]
(25) See, for example: (a) Devanne, D.; Dixneuf, P. H. J. Organomet.
Chem. 1990, 390, 371. (b) Le Bozec, H.; Ouzzine, K.; Dixneuf, P. H.
Organometallics 1991, 10, 2768. (c) Dussel, R.; Pilette, D.; Dixneuf, P. H.;
Fehlhammer, W. P. Organometallics 1991, 10, 3287. (d) K€uc€ukbay, H.;
Cetinkaya, B.; Guesmi, S.; Dixneuf, P. H. Organometallics 1996, 15, 2434.
(e) Mai, J.-F.; Yamamoto, Y. J. Organomet. Chem. 1998, 560, 223.
(f) Yamamoto, Y.; Nakamura, H.; Mai, J.-F. J. Organomet. Chem. 2001,
640, 10. (g) Bhalla, R.; Boxwell, C. J.; Duckett, S. B.; Dyson, P. J.;
Humphrey, D. G.; Steed, J. W.; Suman, P. Organometallics 2002, 21, 924.
(h) Valerga, P.; Puerta, M. C.; Pandey, D. S. J. Organomet. Chem. 2002, 648,
ꢀ
27. (i) Cadierno, V.; Crochet, P.; García-Alvarez, J.; García-Garrido, S. E.;
Gimeno, J. J. Organomet. Chem. 2002, 663, 32. (j) Lastra-Barreira, B.; Díez,
J.; Crochet, P. Green Chem. 2009, 11, 1681.
(26) (a) Singewald, E. T.; Slone, C. S.; Stern, C. L.; Mirkin, C. A.;
Yap, G. P. A.; Liable-Sands, L. M.; Rheingold, A. L. J. Am. Chem. Soc.
1997, 119, 3048. (b) Bowyer, W. J.; Merket, J. W.; Geiger, W. E.; Rheingold,
A. L. Organometallics 1989, 8, 191.

ꢀ
´
Garcıa-Alvarez et al.
3960 Organometallics, Vol. 29, No. 17, 2010
Figure 6. Cyclic voltammograms obtained for [RuCl2{κ1(P)-2-Ph2PC6H4CH2NHiPr}(η6-C6H6)] (11aa) after one (left) and three
successive scans (right). Measured at 0.1 V s-1 in dichloromethane with a 0.03 M solution of [nBu4N][PF6] as the supporting electrolyte.
Table 1. Electrochemical Data for Complexes 11aa-13dba
complex E°0 (V)b ipa/ipc ΔEp (mV) complex E°0 (V)b ipa/ipc ΔEp (mV)
Table 2. Ruthenium-Catalyzed Hydration of Benzonitrile
in Watera
11aa
11ab
11ba
11bb
11ca
11cb
11da
11db
12aa
12ab
12ba
12bb
1.27
1.30
1.12
1.07
1.18
1.09
0.97
0.91
1.14
1.10
0.99
0.95
0.8
0.8
0.8
0.8
0.8
0.9
0.9
0.8
1.0
1.0
1.0
1.0
125
161
202
168
156
147
146
144
137
156
162
168
12ca
12cb
12da
12db
13aa
13ab
13ba
13bb
13ca
13cb
13da
13db
1.07
0.94
0.82
0.78
1.06
0.99
0.95
0.91
0.95
0.96
0.78
0.80
1.0
1.0
0.8
0.8
1.0
1.0
1.1
1.0
1.0
1.2
1.0
1.1
95
165
162
161
150
164
162
144
162
171
155
232
entry
catalyst
yield (%)b
entry
catalyst
yield (%)b
1
2
3
4
5
6
7
8
11aa
11ab
11ba
11bb
11ca
11cb
11da
11db
12aa
12ab
12ba
12bb
12ca
12cb
12da
12db
13aa
13ab
65 (96)
23 (75)
34 (65)
34 (77)
13 (43)
47 (81)
61 (85)
92 (99)
85 (96)
61 (79)
89 (97)
77 (95)
88 (96)
94 (97)
46 (75)
76 (98)
72 (87)
44 (70)
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
13ba
13bb
13ca
13cb
13da
13db
14a
14b
14c
14d
93 (97)
83 (95)
83 (95)
84 (93)
62 (88)
56 (84)
21 (45)
11 (45)
10 (21)
24 (48)
61 (85)
35 (55)
28 (62)
52 (77)
45 (80)
44 (86)
52 (95)
46 (89)
a Measured at 0.1 V s-1 in dichloromethane with a 0.03 M solution of
[nBu4N][PF6] as the supporting electrolyte. b Formal potentials (E°’) are
referenced relative to the potential of the [Cp2Fe]/[Cp2Fe]þ couple (E° =
9
10
11
12
13
14
15
16
17
18
0.21 V) run under identical conditions (E°’ = E°(RuIII/RuII) - E°(FeIII
/
14ac
14ad
14bc
14bd
14cc
14cd
14dc
14dd
FeII)).
(13ba) showed the best performances, generating benzamide in
>90% yield after only 7 h (entries 8, 14, and 19, respectively).
Although those complexes derived from the ortho-substituted
phosphines 2-Ph2PC6H4CH2NHR (entries 1-8) are in general
less active than their meta- (entries 9-16) and para-substituted
counterparts (entries 17-24),27 no direct relationships between
the structure or electronic nature of these species and their
catalytic activity become really evident from the data obtained.
Solubility grounds do not explain the reactivities observed since
homogeneity of the aqueous phase was in all cases observed.28a,b
a Reactions performed under N2 atmosphere at 100 °C using 1 mmol
of benzonitrile (0.33 M in water). Substrate/Ru ratio: 100/5. b Yield after
7 h of heating (yield after 24 h in parentheses). In both cases, yields are
reported as uncorrected GC areas. c Reactions performed in the presence
of 5 mol % of PhCH2NHiPr. d Reactions performed in the presence of
5 mol % of PhCH2NHtBu.
Interestingly, when the related triphenylphosphine-Ru(II)
complexes [RuCl2(PPh3)(η6-arene)] (arene = C6H6 (14a),19
p-cymene (14b),19 1,3,5-C6H3Me3 (14c),29 C6Me6 (14d)30)
were used as catalysts under identical reaction conditions,
benzamide was formed in remarkably lower yields (21-48%
after 24 h; entries 25-28).28c This fact clearly evidences that a
cooperative effect of the amino-phosphine ligands is taking
place. However, since the position of the amino susbtituent
in the aromatic ring (ortho, meta, or para) does not exert a
marked influence on the catalytic activity, such a cooperative
effect of the amino-functionalized ligands 7-9a,b seems to
be unrelated to the effective approach of the nucleophilic
water molecule to the coordinated nitrile, via hydrogen bond-
ing. On the other hand, we have also observed that the effective-
ness of [RuCl2(PPh3)(η6-arene)] (14a-d) is greatly improved
(27) Formation of a stable six-membered chelate ring by intramole-
cular coordination of the pendant amino group to ruthenium could be
responsible for this behavior. In the case of complex [RuCl2{κ1(P)-2-
Ph2PC6H4CH2NHtBu}(η6-C6Me6)] (11db), one of the most active cat-
alysts found in this study, such a chelation process is sterically disfavored
by the presence of the bulky η6-coordinated hexamethylbenzene and the
tert-butyl substituent on the amino-phosphine ligand.
(28) (a) A two-phase system (water/organic products) is observed, the
reaction taking place probably at the interface. (b) We note that the
addition of surfactants does not improve the catalytic activity of these
complexes. On the contrary, it significantly decreases. For example, in
the presence of sodium dodecyl sulfate and cetyltrimethylammonium
bromide (0.05 M solutions), complex [RuCl2{κ1(P)-3-Ph2PC6H4CH2-
NHtBu}(η6-1,3,5-C6H3Me3)] (12cb) (5 mol %) generates benzamide in
only 58% and 60% GC yield, respectively, after 24 h of heating at 100 °C
(to be compared with entry 14 in Table 2). (c) Complexes [RuCl2-
(PPh3)(η6-arene)] (14a-d) are completely insoluble in water at room
temperature, but they become partially soluble at 100 °C. Therefore,
unlike the case of amino-phosphine derivatives 11aa-13db, the aqueous
phase during the catalytic reactions using [RuCl2(PPh3)(η6-arene)]
(14a-d) is not completely homogenous, and consequently, solubility
issues cannot be completely discarded to explain the different reactivities
observed.
(29) Davies, D. L.; Fawcett, J.; Krafczyk, R.; Russell, D. R.; Singh,
K. J. Chem. Soc., Dalton Trans. 1998, 2349.
(30) Werner, H.; Kletzin, H. J. Organomet. Chem. 1982, 228, 289.

Article
Organometallics, Vol. 29, No. 17, 2010 3961
Table 3. Catalytic Hydration of Nitriles in Water Using
Complex 12cba
(11aa-11db), [RuCl2{κ1(P)-3-Ph2PC6H4CH2NHR}(η6-arene)]
(12aa-12db), and [RuCl2{κ1(P)-4-Ph2PC6H4CH2NHR}(η6-
arene)] (13aa-13db), have been synthesized. These readily
accessible species are efficient catalysts for the selective con-
version of organonitriles into amides under challenging reac-
tion conditions, i.e., pure aqueous medium in the absence of
any cocatalyst, being much more active than their corre-
sponding nonfunctionalized triphenylphosphine counter-
parts [RuCl2(PPh3)(η6-arene)]. Experimental results seem
to indicate that complexes 11aa-13db operate through a
“bifunctional catalysis“ mechanism in which the ruthenium
center acts as a Lewis acid, activating the nitrile molecule,
and the amino-phoshine ligand acts as a Brønsted base, the
pendant amino group generating the real nucleophilic spe-
cies of the process, i.e., the OH- group.
entry
substrate
R = Ph
yield after 7 h (%)b yield after 24 h (%)b
1
2
3
4
5
6
7
8
9
94
48
77
64
87
89
50
71
92
98
90
96
81
41
53
97 (84)
90 (79)
99 (87)
94 (80)
99 (88)
99 (90)
83 (70)
98 (86)
99 (90)
99 (88)
99 (91)
99 (87)
89 (74)
55 (40)
80 (72)
R = 2-C6H4F
R = 3-C6H4Cl
R = 4-C6H4Cl
R = 3-C6H4Br
R = 3-C6H4NO2
R = 4-C6H4CO2Et
R = 3-C6H4OMe
R = C6F5
10 R = 3-pyridyl
11 R = CH2-4-C6H4Cl
12 R = CH2-2-Thienyl
13 R = (CH2)2OPh
14 R = n-C5H11
Experimental Section
Synthetic procedures were performed under an atmosphere of
dry nitrogen using vacuum-line and standard Schlenk techni-
ques. Solvents were dried by standard methods and distilled
under nitrogen before use. All reagents were obtained from
commercial suppliers and used without further purification with
the exception of compounds 2-Ph2PC6H4CHO (1),17a,c 3-Ph2-
PC6H4CHO (2),17d 4-Ph2PC6H4CHO (3),17b 2-Ph2PC6H4CHd
NiPr (4a),16a,c 2-Ph2PC6H4CHdNtBu (4b),16a,c 2-Ph2PC6H4-
CH2NHiPr (7a),16d 2-Ph2PC6H4CH2NHtBu (7b),16b,e [{RuCl(μ-Cl)-
(η6-arene)}2] (arene = C6H6 (10a),19 p-cymene (10b),20 1,3,5-
C6H3Me3 (10c),21 C6Me6 (10d)20), and [RuCl2(PPh3)(η6-arene)]
(arene = C6H6 (14a),19 p-cymene (14b),19 1,3,5-C6H3Me3
(14c),29 C6Me6 (14d)30), which were prepared by following the
methods reported in the literature. Infrared spectra were recor-
ded on a Perkin-Elmer 1720-XFT spectrometer. The C, H, and
N analyses were carried out with a Perkin-Elmer 2400 micro-
analyzer. NMR spectra were recorded on a Bruker DPX300
instrument at 300 MHz (1H), 121.5 MHz (31P), or 75.4 MHz
(13C) using SiMe4 or 85% H3PO4 as standard. DEPT experi-
ments have been carried out for all the compounds reported in
this paper.
15 R = (E)-CHdCHPh
a Reactions performed under N2 atmosphere at 100 °C using 1 mmol
of the corresponding nitrile (0.33 M in water). Substrate/Ru ratio: 100/5.
b Yields are reported as uncorrected GC areas (isolated yields are given
in parentheses).
when the catalytic reactions are performed in the presence of
5mol%ofN-isopropylbenzylamine or N-benzyl-tert-butylamine
(entries 29-36), i.e., in basic media. Consequently, we can
conclude that the beneficial effect of the coordinated amino-
phosphines 7-9a,b is more likely related with the activation
of water by deprotonation, thus generating in the reaction
media the more nucleophilic hydroxyl group.31
Using the most active complex [RuCl2{κ1(P)-3-Ph2PC6-
H4CH2NHtBu}(η6-1,3,5-C6H3Me3)] (12cb), the generality of
this catalytic transformation was also evaluated (see Table 3).
Thus, as observed for benzonitrile (entry 1), other aromatic
(entries 2-9) and heteroaromatic (entry 10) substrates could
be selectively converted into the corresponding amides (83-99%
GC yields) after 24 h of heating, regardless of the position
and electronic nature of the substituents present in the aro-
matic ring. Common functional groups (halide, nitro, ester,
ether) were tolerated, and no overhydrolysis to carboxylic
acids was observed, thus demonstrating the wide scope and
synthetic utility of this procedure. Subsequent purification
by column chromatography on silica gel provided analyti-
cally pure samples of the corresponding amides in 70-88%
isolated yields. As shown in entries 11-15, this aqueous pro-
cess is not restricted to aromatic organonitriles, the hydra-
tion of substrates containing alkyl- and alkenyl-CN bonds
being also conveniently achieved under the standard reaction
conditions. However, we must note that in the case of the
aliphatic derivative hexanenitrile (entry 14) only a modest
yield of hexanamide could be reached (55% by CG).
Synthesis of Imino-phosphines 3-Ph2PC6H4CHdNR (R = iPr
(5a), tBu (5b)) and 4-Ph2PC6H4CHdNR (R = iPr (6a), tBu (6b)).
A solution of the corresponding diphenylphosphinobenzalde-
hyde (2, 3; 0.50 g, 1.72 mmol) in 20 mL of a MeOH/CH2Cl2
mixture (1:1 v/v) was treated, at room temperature, with the
appropriate primary amine (17 mmol) for 2 h. Volatiles were
then removed under vacuum, yielding phosphino-imines 5-6a,
b as colorless oils in quantitative yield. 5a: Anal. Calcd for
C
22H22NP: C, 79.74; H, 6.69; N, 4.23. Found: C, 79.65; H, 6.84;
1
N, 4.37. 31P{1H} NMR (CDCl3): δ -5.4 (s) ppm. H NMR
3
(CDCl3): δ 1.27 (d, 6H, JHH = 6.0 Hz, CHMe2), 3.54 (sept,
3
1H, JHH = 6.0 Hz, CHMe2), 7.32-7.89 (m, 14H, CHarom),
8.25 (s, 1H, CHdN) ppm. 13C{1H} NMR (CDCl3): δ 24.3 (s,
CHMe2), 61.7 (s, CHMe2), 127.0-135.6 (m, CHarom and
C
C
arom), 157.9 (s, CHdN) ppm. 5b: Anal. Calcd for
23H24NP: C, 79.97; H, 7.00; N, 4.06. Found: C, 80.15; H,
7.12; N, 4.17. 31P{1H} NMR (CDCl3): δ -5.9 (s) ppm. 1H
NMR (CDCl3): δ 1.29 (s, 9H, CMe3), 7.29-7.98 (m, 14H,
CHarom), 8.22 (s, 1H, CHdN) ppm. 13C{1H} NMR (CDCl3): δ
29.4 (s, CMe3), 57.3 (s, CMe3), 127.7-138.0 (m, CHarom and
Conclusions
C
arom), 154.5 (s, CHdN) ppm. 6a: Anal. Calcd for C22H22NP:
In summary, in this work three series of novel arene-ruth-
enium(II) complexes containing amino-phosphine ligands,
namely, [RuCl2{κ1(P)-2-Ph2PC6H4CH2NHR}(η6-arene)]
C, 79.74; H, 6.69; N, 4.23. Found: C, 79.58; H, 6.87; N, 4.40.
31P{1H} NMR (CDCl3): δ -5.4 (s) ppm. 1H NMR (CDCl3): δ
1.37 (br, 6H, CHMe2), 3.62 (br, 1H, CHMe2), 7.39-7.81 (m,
14H, CHarom), 8.36 (s, 1H, CHdN) ppm. 13C{1H} NMR
(CDCl3): δ 24.4 (s, CHMe2), 61.8 (s, CHMe2), 128.1-134.1
(m, CHarom and Carom), 157.8 (s, CHdN) ppm. 6b: Anal. Calcd
for C23H24NP: C, 79.97; H, 7.00; N, 4.06. Found: C, 80.10; H,
7.19; N, 4.23. 31P{1H} NMR (CDCl3): δ -5.4 (s) ppm. 1H
(31) pH measurements on 0.016 M aqueous solutions of complexes
11aa-13db (the same concentration used in the catalytic experiments)
confirm this hypothesis. The values obtained, ranging from 7.12 to 7.37,
indicate that when dissolved in water 11aa-13db are able to generate a
slightly basic media.

ꢀ
Garcıa-Alvarez et al.
´
3962 Organometallics, Vol. 29, No. 17, 2010
NMR (CDCl3): δ 1.19 (s, 9H, CMe3), 7.41-7.83 (m, 14H,
CHarom), 8.36 (s, 1H, CHdN) ppm. 13C{1H} NMR (CDCl3): δ
29.9 (s, CMe3), 57.3 (s, CMe3), 127.9-140.0 (m, CHarom and
(sept, 1H, 3JHH = 6.0 Hz, CHMe2), 3.40 (br, 2H, CH2), 4.83 and
3
5.33 (d, 2H each, JHH = 6.0 Hz, CH of cym), 7.33-7.91 (m,
14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 17.8 (s, Me of cym), 21.6 and 21.9 (both s, CHMe2),
30.6 (s, CHMe2 of cym), 49.7 (s, CHMe2), 49.9 (s, CH2), 86.9 and
88.3 (s, CH of cym), 98.2 and 111.7 (s, C of cym), 127.7-134.1
(m, CHarom and Carom) ppm. 11bb: Yield: 0.463 g (71%). Anal.
Calcd for RuC33H40Cl2NP: C, 60.64; H, 6.17; N, 2.14. Found:
C, 60.77; H, 6.09; N, 2.20. IR (Nujol, cm-1): ν 3260 (N-H).
C
arom), 154.7 (s, CHdN) ppm.
Synthesis of Amino-phosphines 3-Ph2PC6H4CH2NHR (R =
iPr (8a), tBu (8b)) and 4-Ph2PC6H4CH2NHR (R = iPr (9a), tBu
(9b)). A solution of the corresponding imino-phosphine (5-6a,b;
1.5 mmol) in 20 mL of methanol was treated by NaBH4 (0.208 g,
5.5 mmol) at 0 °C for 45 min. The reaction was then quenched with
aqueous NaOH (5 mL, 1 M), the organic layer was extracted with
dichloromethane (3 ꢀ 15 mL), and the combined phases were
dried over MgSO4. Solvent removal under reduced pressure
afforded amino-phosphines 8-9a,b as pale yellow oils. 8a: Yield:
0.400 g (80%). Anal. Calcd for C22H24NP: C, 79.25; H, 7.26; N,
4.20. Found: C, 79.33; H, 7.39; N, 4.41. 31P{1H} NMR (CDCl3): δ
-5.4 (s) ppm. 1H NMR (CDCl3): δ 1.10 (d, 6H, 3JHH = 6.0 Hz,
CHMe2), 2.84 (m, 1H, CHMe2), 3.79 (br, 2H, CH2), 7.19-7.38
(m, 14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CDCl3): δ 22.9 (s, CHMe2), 48.0 (s, CHMe2), 51.4 (s, CH2),
128.5-132.3 (m, CHarom and Carom) ppm. 8b: Yield: 0.395 g
(76%). Anal. Calcd for C23H26NP: C, 79.51; H, 7.54; N, 4.03.
Found: C, 79.67; H, 7.59; N, 4.12. 31P{1H} NMR (CDCl3): δ -5.3
(s) ppm. 1H NMR (CDCl3): δ 1.16 (s, 9H, CMe3), 3.72 (br, 2H,
CH2), 7.12-7.38 (m, 14H, CHarom) ppm; NH signal not observed.
13C{1H} NMR (CDCl3): δ 29.6 (s, CMe3), 47.5 (s, CH2), 51.2 (s,
CMe3), 128.8-134.2 (m, CHarom and Carom) ppm. 9a: Yield: 0.415
g (83%). Anal. Calcd for C22H24NP: C, 79.25; H, 7.26; N, 4.20.
Found: C, 79.41; H, 7.15; N, 4.33. 31P{1H} NMR (CD2Cl2): δ
-6.2 (s) ppm. 1H NMR (CD2Cl2): δ 1.24 (d, 6H, 3JHH = 6.0 Hz,
CHMe2), 3.02 (m, 1H, CHMe2), 3.95 (br, 2H, CH2), 7.47-7.88
(m, 14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 23.1 (s, CHMe2), 48.4 (s, CHMe2), 51.3 (s, CH2),
128.4-143.0 (m, CHarom and Carom) ppm. 9b: Yield: 0.412 g
(79%). Anal. Calcd for C23H26NP: C, 79.51; H, 7.54; N, 4.03.
Found: C, 79.59; H, 7.65; N, 4.17. 31P{1H} NMR (CDCl3): δ -6.1
(s) ppm. 1H NMR (CDCl3): δ 1.28 (s, 9H, CMe3), 3.83 (br, 2H,
CH2), 7.36-7.45 (m, 14H, CHarom) ppm; NH signal not observed.
13C{1H} NMR (CDCl3): δ 24.4 (s, CMe3), 47.1 (s, CH2), 50.7 (s,
CMe3), 128.5-143.0 (m, CHarom and Carom) ppm.
1
31P{1H} NMR (CDCl3): δ 26.5 (s) ppm. H NMR (CDCl3): δ
0.75 (s, 9H, CMe3), 1.27 (d, 6H, 3JHH = 7.0 Hz, CHMe2 of cym),
1.84 (s, 3H, Me of cym), 2.89 (sept, 1H, 3JHH = 7.0 Hz, CHMe2
of cym), 3.22 (br, 2H, CH2), 4.84 and 5.31 (d, 2H each, 3JHH
=
4.8 Hz, CH of cym), 7.35-7.95 (m, 14H, CHarom) ppm; NH
signal not observed. 13C{1H} NMR (CD2Cl2): δ 17.8 (s, Me of
cym), 21.9 (s, CHMe2 of cym), 28.5 (s, CMe3), 30.5 (s, CHMe2 of
cym), 46.0 (s, CH2), 50.2 (s, CMe3), 87.3 and 87.9 (s, CH of cym),
98.0 and 110.9 (s, C of cym), 126.2-137.2 (m, CHarom and
C
arom) ppm. 11ca: Yield: 0.400 g (64%). Anal. Calcd for
RuC31H36Cl2NP: C, 59.52; H, 5.80; N, 2.24. Found: C, 59.60;
H, 5.86; N, 2.32. IR (Nujol, cm-1): ν 3298 (N-H). 31P{1H}
NMR (CD2Cl2): δ 30.7 (s) ppm. 1H NMR (CD2Cl2): δ 0.69 (d,
6H, 3JHH = 6.0 Hz, CHMe2), 2.02 (s, 9H, C6H3Me3), 3.24 (m,
3H, CHMe2 and CH2), 4.60 (s, 3H, C6H3Me3), 7.39-8.30 (m,
14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 18.3 (s, C6H3Me3), 22.4 (s, CHMe2), 49.0 (s,
2
CHMe2), 50.6 (s, CH2), 84.8 (d, JCP = 4.5 Hz, CH of
C6H3Me3), 104.6 (s, C of C6H3Me3), 126.3-145.6 (m, CHarom
and Carom) ppm. 11cb: Yield: 0.396 g (62%). Anal. Calcd for
RuC32H38Cl2NP: C, 60.09; H, 5.99; N, 2.19. Found: C, 60.15; H,
5.87; N, 2.22. IR (Nujol, cm-1): ν 3248 (N-H). 31P{1H} NMR
1
(CD2Cl2): δ 30.7 (s) ppm. H NMR (CD2Cl2): δ 1.19 (s, 9H,
CMe3), 2.02 (s, 9H, C6H3Me3), 3.16 (br, 2H, CH2), 4.61 (s, 3H,
C6H3Me3), 7.39-8.31 (m, 14H, CHarom) ppm; NH signal not
observed. 13C{1H} NMR (CD2Cl2): δ 18.3 (s, C6H3Me3), 28.5 (s,
CMe3), 46.2 (s, CH2), 50.0 (s, CMe3), 84.8 (d, 2JCP = 3.4 Hz, CH
2
of C6H3Me3), 104.7 (d, JCP = 3.4 Hz, C of C6H3Me3),
125.9-147.0 (m, CHarom and Carom) ppm. 11da: Yield: 0.594 g
(89%). Anal. Calcd for RuC34H42Cl2NP: C, 61.16; H, 6.34; N,
2.10. Found: C, 60.97; H, 6.36; N, 2.19. IR (Nujol, cm-1): ν 3270
(N-H). 31P{1H} NMR (CD2Cl2): δ 30.1 (s) ppm. 1H NMR
(CD2Cl2): δ 0.68 (br, 6H, CHMe2), 1.75 (s, 18H, C6Me6), 3.01
(m, 1H, CHMe2), 3.72 (br, 2H, CH2), 7.15-7.91 (m, 14H,
CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 14.7 (s, C6Me6), 22.6 (s, CHMe2), 48.7 (s, CHMe2),
50.8 (s, CH2), 96.5 (s, C6Me6), 125.6-139.5 (m, CHarom and
Carom) ppm. 11db: Yield: 0.538 g (79%). Anal. Calcd for
RuC35H44Cl2NP: C, 61.67; H, 6.51; N, 2.05. Found: C, 61.60;
H, 6.64; N, 2.15. IR (Nujol, cm-1): ν 3291 (N-H). 31P{1H}
NMR (CD2Cl2): δ 30.1 (s) ppm. 1H NMR (CD2Cl2): δ 0.67 (s,
9H, CMe3), 1.73 (s, 18H, C6Me6), 3.26 (br, 2H, CH2), 7.15-7.85
(m, 14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 14.8 (s, C6Me6), 28.5 (s, CMe3), 46.1 (s, CH2), 50.0
Synthesis of Complexes [RuCl2{K1(P)-2-Ph2PC6H4CH2NHR}-
(η6-arene)] (arene = C6H6, R = iPr (11aa), tBu (11ab); arene =
p-cymene, R = iPr (11ba), tBu (11bb); arene = 1,3,5-C6H3Me3,
R = iPr (11ca), tBu (11cb); arene = C6Me6, R = iPr (11da), tBu
(11db)). A solution of the corresponding dimer [{RuCl(μ-Cl)(η6-
arene)}2] (10a-d; 0.5 mmol) in 40 mL of tetrahydrofuran was
treated, at room temperature, with the appropriate amino-
phosphine ligand 7a,b (1 mmol) for 2 h (24 h when 10a is used
as starting material). The resulting solution was then evaporated
to dryness, thus yielding a microcrystalline orange-red solid,
which was washed with a 1:2 mixture of diethyl ether/hexane
(3 ꢀ 10 mL) and vacuum-dried. 11aa: Yield: 0.426 g (73%).
Anal. Calcd for RuC28H30Cl2NP: C, 57.64; H, 5.18; N, 2.40.
Found: C, 57.71; H, 5.22; N, 2.53. IR (Nujol, cm-1): ν 3204
(N-H). 31P{1H} NMR (CD2Cl2): δ 28.9 (s) ppm. 1H NMR
(CD2Cl2): δ 0.88 (d, 6H, 3JHH = 6.0 Hz, CHMe2), 2.50 (m, 1H,
CHMe2), 3.59 (br, 2H, CH2), 5.47 (s, 6H, C6H6), 7.35-7.86 (m,
14H, CHarom) ppm; NH signal not observed. 11ab: Yield: 0.382
g (64%). Anal. Calcd for RuC29H32Cl2NP: C, 58.29; H, 5.40; N,
2.34. Found: C, 58.20; H, 5.48; N, 2.45. IR (Nujol, cm-1): ν 3211
(N-H). 31P{1H} NMR (CD2Cl2): δ 28.3 (s) ppm. 1H NMR
(CD2Cl2): δ 0.84 (s, 9H, CMe3), 3.44 (br, 2H, CH2), 5.44 (s, 6H,
C6H6), 7.38-7.94 (m, 14H, CHarom) ppm; NH signal not
observed. 13C{1H} NMR (CD2Cl2): δ 27.8 (s, CMe3), 45.9 (s,
2
(s, CMe3), 96.5 (d, JCP = 3.0 Hz, C6Me6), 125.5-147.0 (m,
CHarom and Carom) ppm.
Synthesis of Complexes [RuCl2{K1(P)-3-Ph2PC6H4CH2NHR}-
(η6-arene)] (arene = C6H6, R = iPr (12aa), tBu (12ab); arene =
p-cymene, R = iPr (12ba), tBu (12bb); arene = 1,3,5-C6H3Me3,
R = iPr (12ca), tBu (12cb); arene = C6Me6, R = iPr (12da), tBu
(12db)). Complexes 12aa-12db, isolated as orange microcrys-
talline solids, were prepared as described for 11aa-11db start-
ing from the appropriate [{RuCl(μ-Cl)(η6-arene)}2] dimer
(10a-d; 0.5 mmol) and amino-phosphine ligand 8a,b (1.2
2
CH2), 51.2 (s, CMe3), 89.4 (d, JCP = 3.1 Hz, C6H6),
mmol). 12aa: Yield: 0.414 g (71%). Anal. Calcd for
128.0-134.4 (m, CHarom and Carom) ppm. 11ba: Yield: 0.441 g
(69%). Anal. Calcd for RuC32H38Cl2NP: C, 60.09; H, 5.99; N,
2.19. Found: C, 59.91; H, 6.12; N, 2.31. IR (Nujol, cm-1): ν 3317
(N-H). 31P{1H} NMR (CD2Cl2): δ 27.4 (s) ppm. 1H NMR
(CD2Cl2): δ 0.79 (br, 6H, CHMe2), 1.28 (d, 6H, 3JHH = 6.0 Hz,
CHMe2), 1.82 (s, 3H, Me of cym), 2.29 (br, 1H, CHMe2), 2.93
RuC28H30Cl2NP: C, 57.64; H, 5.18; N, 2.40. Found: C,
57.72; H, 5.09; N, 2.51. IR (Nujol, cm-1): ν 3293 (N-H).
31P{1H} NMR (CD2Cl2): δ 28.0 (s) ppm. 1H NMR (CD2Cl2): δ
1.05 (d, 6H, 3JHH = 6.0 Hz, CHMe2), 2.77 (sept, 1H, 3JHH
=
6.0 Hz, CHMe2), 3.79 (br, 2H, CH2), 5.42 (s, 6H, C6H6),
7.35-7.79 (m, 14H, CHarom) ppm; NH signal not observed.

Article
Organometallics, Vol. 29, No. 17, 2010 3963
13C{1H} NMR (CD2Cl2): δ 22.7 (s, CHMe2), 48.1 (s, CHMe2),
50.8 (s, CH2), 89.3 (d, 2JCP = 4.0 Hz, C6H6), 128.0-141.1 (m,
CHarom and Carom) ppm. 12ab: Yield: 0.370 g (62%). Anal.
Calcd for RuC29H32Cl2NP: C, 58.29; H, 5.40; N, 2.34. Found:
C, 58.35; H, 5.29; N, 2.33. IR (Nujol, cm-1): ν 3280 (N-H).
31P{1H} NMR (CD2Cl2): δ 28.3 (s) ppm. 1H NMR (CD2Cl2): δ
1.14 (s, 9H, CMe3), 3.75 (br, 2H, CH2), 5.43 (s, 6H, C6H6),
7.35-7.87 (m, 14H, CHarom) ppm; NH signal not observed.
13C{1H} NMR (CD2Cl2): δ 29.0 (s, CMe3), 46.6 (s, CH2), 50.7 (s,
Synthesis of Complexes [RuCl2{K1(P)-4-Ph2PC6H4CH2NHR}-
(η6-arene)] (arene = C6H6, R = iPr (13aa), tBu (13ab); arene =
p-cymene, R = iPr (13ba), tBu (13bb); arene = 1,3,5-C6H3Me3,
R = iPr (13ca), tBu (13cb); arene = C6Me6, R = iPr (13da), tBu
(13db)). Complexes 13aa-13db, isolated as orange microcrys-
talline solids, were prepared as described for 11aa-11db starting
from the appropriate [{RuCl(μ-Cl)(η6-arene)}2] dimer (10a-d;
0.5 mmol) and amino-phosphine ligand 9a,b (1.2 mmol). 13aa:
Yield: 0.391 g (67%). Anal. Calcd for RuC28H30Cl2NP: C,
57.64; H, 5.18; N, 2.40. Found: C, 57.50; H, 5.31; N, 2.55. IR
(Nujol, cm-1): ν 3270 (N-H). 31P{1H} NMR (CD2Cl2): δ 26.8
(s) ppm. 1H NMR (CD2Cl2): δ 1.21 (br, 6H, CHMe2), 2.91 (br,
1H, CHMe2), 3.81 (br, 2H, CH2), 5.43 (s, 6H, C6H6), 7.41-7.77
(m, 14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 28.5 (s, CHMe2), 46.5 (s, CH2), 48.5 (s, CHMe2),
89.3 (s, C6H6), 126.1-143.5 (m, CHarom and Carom) ppm. 13ab:
Yield: 0.376 g (63%). Anal. Calcd for RuC29H32Cl2NP: C,
58.29; H, 5.40; N, 2.34. Found: C, 58.13; H, 5.51; N, 2.44. IR
(Nujol, cm-1): ν 3275 (N-H). 31P{1H} NMR (CD2Cl2): δ 26.8
(s) ppm. 1H NMR (CD2Cl2): δ 1.22 (s, 9H, CMe3), 3.83 (br, 2H,
CH2), 5.43 (s, 6H, C6H6), 7.40-7.77 (m, 14H, CHarom) ppm; NH
signal not observed. 13C{1H} NMR (CD2Cl2): δ 28.2 (s, CMe3),
46.4 (s, CH2), 52.4 (s, CMe3), 89.3 (s, C6H6), 128.1-142.5 (m,
CHarom and Carom) ppm. 13ba: Yield: 0.454 g (71%). Anal.
Calcd for RuC32H38Cl2NP: C, 60.09; H, 5.99; N, 2.19. Found:
C, 60.18; H, 5.91; N, 2.23. IR (Nujol, cm-1): ν 3317 (N-H).
CMe3), 89.3 (s, C6H6), 128.0-142.3 (m, CHarom and Carom
)
ppm. 12ba: Yield: 0.498 (78%). Anal. Calcd for
g
RuC32H38Cl2NP: C, 60.09; H, 5.99; N, 2.19. Found: C, 60.22;
H, 6.08; N, 2.01. IR (Nujol, cm-1): ν 3302 (N-H). 31P{1H}
NMR (CDCl3): δ 24.2 (s) ppm. 1H NMR (CDCl3): δ 1.06 and
1.11 (d, 6H each, 3JHH = 6.0 Hz, CHMe2), 1.90 (s, 3H, Me of
cym), 2.82 (m, 2H, CHMe2), 3.78 (br, 2H, CH2), 5.04 and 5.22
(d, 2H each, 3JHH = 6.0 Hz, CH of cym), 7.32-7.92 (m, 14H,
CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 17.5 (s, Me of cym), 21.7 and 22.8 (s, CHMe2),
30.3 (s, CHMe2 of cym), 47.9 (s, CHMe2), 51.0 (s, CH2), 87.3 and
89.0 (s, CH of cym), 96.4 and 110.2 (s, C of cym), 127.8-142.2
(m, CHarom and Carom) ppm. 12bb: Yield: 0.471 g (72%). Anal.
Calcd for RuC33H40Cl2NP: C, 60.64; H, 6.17; N, 2.14. Found:
C, 60.51; H, 6.23; N, 2.20. IR (Nujol, cm-1): ν 3302 (N-H).
1
31P{1H} NMR (CDCl3): δ 24.5 (s) ppm. H NMR (CDCl3): δ
1.12 (d, 6H, 3JHH = 6.0 Hz, CHMe2 of cym), 1.17 (s, 9H, CMe3),
1.90 (s, 3H, Me of cym), 2.87 (sept, 1H, 3JHH = 6.0 Hz, CHMe2
1
31P{1H} NMR (CDCl3): δ 23.7 (s) ppm. H NMR (CDCl3): δ
1.13 (d, 12H, 3JHH = 6.0 Hz, CHMe2), 1.90 (s, 3H, Me of cym),
2.88 (m, 2H, CHMe2), 3.83 (br, 2H, CH2), 5.02 and 5.22 (d, 2H
of cym), 3.75 (br, 2H, CH2), 5.03 and 5.23 (d, 2H each, 3JHH
=
6.2 Hz, CH of cym), 7.31-7.94 (m, 14H, CHarom) ppm; NH
signal not observed. 13C{1H} NMR (CD2Cl2): δ 17.7 (s, Me of
cym), 21.8 (s, CHMe2 of cym), 29.0 (s, CMe3), 30.4 (s, CHMe2 of
cym), 46.8 (s, CH2), 50.6 (s, CMe3), 87.5 and 88.9 (s, CH of cym),
96.4 and 110.3 (s, C of cym), 127.7-142.1 (m, CHarom and
Carom) ppm. 12ca: Yield: 0.406 g (65%). Anal. Calcd for
RuC31H36Cl2NP: C, 59.52; H, 5.80; N, 2.24. Found: C, 59.44;
H, 5.92; N, 2.30. IR (Nujol, cm-1): ν 3306 (N-H). 31P{1H}
NMR (CD2Cl2): δ 33.1 (s) ppm. 1H NMR (CD2Cl2): δ 1.09 (d,
6H, 3JHH = 6.8 Hz, CHMe2), 2.03 (s, 9H, C6H3Me3), 2.82 (m,
1H, CHMe2), 3.82 (br, 2H, CH2), 4.71 (s, 3H, C6H3Me3),
7.40-7.86 (m, 14H, CHarom) ppm; NH signal not observed.
13C{1H} NMR (CD2Cl2): δ 18.2 (s, C6H3Me3), 22.6 (s, CHMe2),
48.1 (s, CHMe2), 50.8 (s, CH2), 85.4 (d, 2JCP = 4.5 Hz, CH of
each, 3JHH = 6.0 Hz, CH of cym), 7.35-7.88 (m, 14H, CHarom
)
ppm; NH signal not observed. 13C{1H} NMR (CD2Cl2): δ 17.6
(s, Me of cym), 21.8 and 22.5 (s, CHMe2), 30.4 (s, CHMe2 of
cym), 48.4 (s, CHMe2), 50.7 (s, CH2), 87.3 and 89.2 (s, CH of
cym), 96.3 and 110.2 (s, C of cym), 127.6-143.0 (m, CHarom and
C
arom) ppm. 13bb: Yield: 0.490 g (75%). Anal. Calcd for
RuC33H40Cl2NP: C, 60.64; H, 6.17; N, 2.14. Found: C, 60.80;
H, 6.02; N, 2.25. IR (Nujol, cm-1): ν 3317 (N-H). 31P{1H}
NMR (CDCl3): δ 23.7 (s) ppm. 1H NMR (CDCl3): δ 1.13 (d, 6H,
3JHH = 6.7 Hz, CHMe2 of cym), 1.20 (s, 9H, CMe3), 1.89 (s, 3H,
3
Me of cym), 2.88 (sept, 1H, JHH = 6.7 Hz, CHMe2 of cym),
3.76 (br, 2H, CH2), 5.01 and 5.21 (d, 2H each, 3JHH = 5.4 Hz,
CH of cym), 7.30-7.87 (m, 14H, CHarom) ppm; NH signal not
observed. 13C{1H} NMR (CD2Cl2): δ 17.5 (s, Me of cym), 21.7
(s, CHMe2 of cym), 28.8 (s, CMe3), 30.3 (s, CHMe2 of cym), 46.6
(s, CH2), 50.6 (s, CMe3), 87.3 and 89.1 (s, CH of cym), 96.2 and
110.3 (s, C of cym), 127.6-144.0 (m, CHarom and Carom) ppm.
13ca: Yield: 0.419 g (67%). Anal. Calcd for RuC31H36Cl2NP: C,
59.52; H, 5.80; N, 2.24. Found: C, 59.61; H, 5.72; N, 2.11. IR
(Nujol, cm-1): ν 3301 (N-H). 31P{1H} NMR (CDCl3): δ 31.1 (s)
2
C6H3Me3), 104.5 (d, JCP = 2.3 Hz, C of C6H3Me3),
127.6-141.0 (m, CHarom and Carom) ppm. 12cb: Yield: 0.409 g
(64%). Anal. Calcd for RuC32H38Cl2NP: C, 60.09; H, 5.99; N,
2.19. Found: C, 59.92; H, 6.06; N, 2.25. IR (Nujol, cm-1): ν 3312
(N-H). 31P{1H} NMR (CD2Cl2): δ 33.4 (s) ppm. 1H NMR
(CD2Cl2): δ 1.19 (s, 9H, CMe3), 2.02 (s, 9H, C6H3Me3), 3.80 (br,
2H, CH2), 4.72 (s, 3H, C6H3Me3), 7.37-7.95 (m, 14H, CHarom
)
3
ppm; NH signal not observed. 13C{1H} NMR (CD2Cl2): δ 18.2
(s, C6H3Me3), 28.9 (s, CMe3), 46.7 (s, CH2), 50.7 (s, CMe3), 85.3
(d, 2JCP = 4.0 Hz, CH of C6H3Me3), 104.6 (d, 2JCP = 3.0 Hz, C
of C6H3Me3), 127.6-141.8 (m, CHarom and Carom) ppm. 12da:
Yield: 0.580 g (87%). Anal. Calcd for RuC34H42Cl2NP: C,
61.16; H, 6.34; N, 2.10. Found: C, 61.31; H, 6.26; N, 2.22. IR
(Nujol, cm-1): ν 3270 (N-H). 31P{1H} NMR (CD2Cl2): δ 29.8
ppm. 1H NMR (CDCl3): δ 1.13 (d, 6H, JHH = 6.0 Hz,
3
CHMe2), 2.03 (s, 9H, C6H3Me3), 2.89 (sept, 1H, JHH = 6.0
Hz, CHMe2), 3.82 (br, 2H, CH2), 4.67 (s, 3H, C6H3Me3),
7.36-7.79 (m, 14H, CHarom) ppm; NH signal not observed.
13C{1H} NMR (CD2Cl2): δ 18.2 (s, C6H3Me3), 22.8 (s, CHMe2),
48.5 (s, CHMe2), 51.0 (s, CH2), 85.5 (d, 2JCP = 5.0 Hz, CH of
C6H3Me3), 104.3 (s, C of C6H3Me3), 127.3-143.9 (m, CHarom
and Carom) ppm. 13cb: Yield: 0.428 g (67%). Anal. Calcd for
RuC32H38Cl2NP: C, 60.09; H, 5.99; N, 2.19. Found: C, 59.89; H,
6.13; N, 2.21. IR (Nujol, cm-1): ν 3294 (N-H). 31P{1H} NMR
1
3
(s) ppm. H NMR (CD2Cl2): δ 1.12 (d, 6H, JHH = 9.0 Hz,
CHMe2), 1.77 (s, 18H, C6Me6), 2.79 (m, 1H, CHMe2), 3.79 (br,
2H, CH2), 7.40-7.78 (m, 14H, CHarom) ppm; NH signal not
observed. 13C{1H} NMR (CD3OD): δ 12.7 (s, C6Me6), 19.2 (s,
CHMe2), 45.7 (s, CHMe2), 48.3 (s, CH2), 95.3 (s, C6Me6),
125.9-133.8 (m, CHarom and Carom) ppm. 12db: Yield: 0.559 g
(82%). Anal. Calcd for RuC35H44Cl2NP: C, 61.67; H, 6.51; N,
2.05. Found: C, 61.56; H, 6.47; N, 2.13. IR (Nujol, cm-1): ν 3230
(N-H). 31P{1H} NMR (CD2Cl2): δ 30.3 (s) ppm. 1H NMR
(CD2Cl2): δ 1.15 (s, 9H, CMe3), 1.75 (s, 18H, C6Me6), 3.73 (br,
2H, CH2), 7.40-7.82 (m, 14H, CHarom) ppm; NH signal not
observed. 13C{1H} NMR (CD2Cl2): δ 14.8 (s, C6Me6), 28.8 (s,
1
(CD2Cl2): δ 32.1 (s) ppm. H NMR (CD2Cl2): δ 1.19 (s, 9H,
CMe3), 2.02 (s, 9H, C6H3Me3), 3.79 (br, 2H, CH2), 4.68 (s, 3H,
C6H3Me3), 7.41-7.76 (m, 14H, CHarom) ppm; NH signal not
observed. 13C{1H} NMR (CD2Cl2): δ 18.3 (s, C6H3Me3), 28.9 (s,
CMe3), 46.6 (s, CH2), 50.6 (s, CMe3), 85.6 (s, CH of C6H3Me3),
104.4 (s, C of C6H3Me3), 127.4-144.7 (m, CHarom and Carom
)
ppm. 13da: Yield: 0.561 (84%). Anal. Calcd for
g
RuC34H42Cl2NP: C, 61.16; H, 6.34; N, 2.10. Found: C, 61.29;
H, 6.46; N, 2.01. IR (Nujol, cm-1): ν 3290 (N-H). 31P{1H}
NMR (CDCl3): δ 28.8 (s) ppm. 1H NMR (CDCl3): δ 1.12 (d, 6H,
3JHH = 6.0 Hz, CHMe2), 1.76 (s, 18H, C6Me6), 2.88 (m, 1H,
2
CMe3), 46.9 (s, CH2), 50.6 (s, CMe3), 96.7 (d, JCP = 3.0 Hz,
C6Me6), 127.5-141.7 (m, CHarom and Carom) ppm.

ꢀ
´
Garcıa-Alvarez et al.
3964 Organometallics, Vol. 29, No. 17, 2010
Table 4. Crystal Data and Structure Refinement Details for Compounds 11bb HCl, 12bb, and 13bb
3
11bb HCl
3
12bb
13bb
chemical formula
fw
RuC33H41Cl3NP
690.06
293(2)
1.5418
monoclinic
P21/n
0.101 ꢀ 0.057 ꢀ 0.028
18.1728(2)
10.3861(1)
18.3489(3)
90
111.663(2)
90
4
3218.65(7)
1.424
6.868
RuC33H40Cl2NP
653.60
293(2)
1.5418
triclinic
P1
RuC33H40Cl2NP
653.60
293(2)
1.5418
monoclinic
P21/n
0.125 ꢀ 0.099 ꢀ 0.031
11.6372(1)
19.7352(2)
13.9921(1)
90
106.732(1)
90
4
3077.41(5)
1.411
6.372
T, K
wavelength, A
˚
cryst syst
space group
cryst size, mm
0.086 ꢀ 0.062 ꢀ 0.025
˚
a, A
9.8513(3)
˚
b, A
10.3852(3)
15.9639(4)
89.619(2)
76.419(2)
79.882(2)
˚
c, A
R, deg
β, deg
γ, deg
Z
2
3
˚
V, A
F
1561.85(8)
1.390
6.278
calcd, g cm-3
μ, mm-1
F(000)
1424
676
1352
θ range, deg
index ranges
2.92 to 73.92
-22 e h e 22
-12 e k e 12
-22 e l e 17
96.9%
18 786
6320 (Rint = 0.0234)
516/0
2.85 to 74.01
-12 e h e 12
-12 e k e 12
-18 e l e 19
99.4%
3.99 to 73.81
-14 e h e 14
-23 e k e 15
-17 e l e 16
96.9%
17 444
6042 (Rint = 0.0279)
353/0
completeness to θmax
no. of data collected
no. of unique data
no. of params/restraints
refinement method
goodness of fit on F2
weight function (a, b)
R1a [I > 2σ(I)]
18 252
6304 (Rint = 0.0254)
417/3
full-matrix least-squares on F2
1.033
1.083
1.063
0.0535, 1.922
0.0327
0.0923
0.0363
0.0945
0.0638, 0.7391
0.0354
0.0957
0.0392
0.0992
0.0577, 1.1784
0.0348
0.0880
0.0417
0.0961
wR2a [I > 2σ(I)]
R1 (all data)
wR2 (all data)
largest diff peak
1.263 and -0.779
0.787 and -0.648
0.809 and -0.379
-3
˚
and hole, e A
P
P
P
P
a R1 = (|Fo| - |Fc|)/ |Fo|; wR2 = { [w(Fo2 - Fc2)2]/ [w(Fo2)2]}1/2
.
CHMe2), 3.81 (br, 2H, CH2), 7.39-7.79 (m, 14H, CHarom) ppm;
NH signal not observed. 13C{1H} NMR (CD2Cl2): δ 14.8
(s, C6Me6), 22.1 (s, CHMe2), 48.4 (s, CH2), 50.5 (s, CHMe2),
96.7 (d, 2JCP = 3.8 Hz, C6Me6), 127.4-135.2 (m, CHarom and
taking samples of 20 μL, which after extraction with CH2Cl2
(3 mL) were analyzed by GC. After elimination of the solvent
under reduced pressure, the crude reaction mixture was purified
by column chromatography over silica gel using diethyl ether as
eluent. The identity of the resulting amides was assessed by
comparison of their 1H and 13C{1H} NMR spectroscopic data
with those reported in the literature and by their fragmentation
in GC/MSD.
C
arom) ppm. 13db: Yield: 0.552 g (81%). Anal. Calcd for
RuC35H44Cl2NP: C, 61.67; H, 6.51; N, 2.05. Found: C, 61.78;
H, 6.55; N, 1.97. IR (Nujol, cm-1): ν 3174 (N-H). 31P{1H}
NMR (CD2Cl2): δ 29.2 (s) ppm. 1H NMR (CD2Cl2): δ 1.21 (s,
9H, CMe3), 1.77 (s, 18H, C6Me6), 3.80 (br, 2H, CH2), 7.43-7.18
(m, 14H, CHarom) ppm; NH signal not observed. 13C{1H} NMR
(CD2Cl2): δ 14.9 (s, C6Me6), 28.8 (s, CMe3), 46.6 (s, CH2), 50.9
X-ray Crystal Structure Determination of Complexes
11bb HCl, 12bb, and 13bb. Crystals suitable for X-ray diffrac-
3
tion analysis were obtained by slow diffusion of n-pentane into
saturated solutions of the appropriate complex in dichloro-
methane. The most relevant crystal and refinement data are
collected in Table 4. For all crystals, data collection was per-
formed on an Oxford Diffraction Xcalibur Nova single-crystal
(s, CMe3), 96.7 (s, C6Me6), 127.5-144.2 (m, CHarom and Carom
ppm.
)
Electrochemistry. CV measurements (25 °C) were carried out
with a three-electrode system. The working electrode was a
platinum disk electrode, the counter electrode was a platinum
spiral, and the reference electrode was an aqueous saturated
calomel electrode separated from the solution by a porous
septum. Current and voltage parameters were controlled using
a PAR system M273. In a typical experiment, 0.15 mmol of the
complex was dissolved under a nitrogen atmosphere in 10 mL of
freshly distilled and deoxygenated dichloromethane containing
1.15 g of pure [nBu4N][PF6] (0.3 mmol) as electrolyte. Formal
CV potentials (E°0) given in Table 1 are referenced relative to the
potential of the [Cp2Fe]/[Cp2Fe]þ couple (E° = 0.21 V) run
˚
diffractometer, using Cu KR radiation (λ = 1.5418 A). Images
were collected at a 65 mm fixed crystal-detector distance, using
the oscillation method, with 1° oscillation and variable exposure
time per image (3-40 s). Data collection strategy was calculated
with the program CrysAlis Pro CCD.32 Data reduction and cell
refinement were performed with the program CrysAlis Pro
RED.32 An empirical absorption correction was applied using
the SCALE3 ABSPACK algorithm as implemented in the
program CrysAlis Pro RED.32 The software package WINGX33
was used for space group determination, structure solution, and
under identical conditions (E°0 = E°(RuIII/RuII) - E°(FeIII
/
refinement. The structures of complexes 11bb HCl and 13bb
3
FeII)).24
were solved by direct methods using SIR2004.34 For 12bb the
structure was solved by Patterson interpretation and phase
expansion using DIRDIF.35
General Procedure for the Catalytic Hydration Reactions.
Under nitrogen atmosphere, the corresponding nitrile (1 mmol),
water (3 mL), and the appropriate ruthenium catalyst (5 mol %
of Ru) were introduced into a sealed tube, and the reaction
mixture was stirred at 100 °C for the indicated time (see Tables 2
and 3). The course of the reaction was monitored by regularly
(32) CrysAlisPro CCD, CrysAlisPro RED; Oxford Diffraction Ltd.:
Abingdon, Oxfordshire, UK, 2008.
(33) Farrugia, L. J. J. Appl. Crystallogr. 1999, 32, 837.

Article
Isotropic least-squares refinement on F2 using SHELXL9736
Organometallics, Vol. 29, No. 17, 2010 3965
2
σ(Fo2) from counting statistics and P = (max(Fo2,0) þ 2Fc )/3.
was performed. During the final stages of the refinements, all the
positional parameters and the anisotropic temperature factors
of all the non-H atoms were refined. For 11bb HCl and 12bb the
Atomic scattering factors were taken from the International
Tables for X-ray Crystallography.37 Geometrical calculations
were made with PARST.38 The crystallographic plots were
made with PLATON.39
3
coordinates of H atoms were found from different Fourier maps
and included in a refinement with isotropic parameters (except
those of the CH3 groups of 12bb, which were geometrically
located and their coordinates refined riding on their parent
atoms). For 13bb, the H atoms were geometrically located and
their coordinates were refined riding on their parent atoms
(except HN1, which was found from different Fourier maps
and included in a refinement with isotropic parameters). The
Acknowledgment. Financial support from the Spanish
MICINN (Projects CTQ2006-08485/BQU and CSD2007-
00006) and the Gobierno del Principado de Asturias
(FICYT Project IB08-036) is acknowledged.
P
P
function minimized was [ w(Fo2 - Fc )/ w(Fo2)]1/2 where w =
2
Supporting Information Available: CIF file giving crystal-
lographic data for compounds 11bb HCl, 12bb, and 13bb. This
1/[σ2(Fo2) þ (aP)2 þ bP] (a and b values are given in Table 4) with
3
material is available free of charge via the Internet at http://
pubs.acs.org.
(34) Burla, M. C.; Caliandro, R.; Camalli, M.; Carrozzini, B.;
Cascarano, G. L.; De Caro, L.; Giacovazzo, C.; Polidori, G.; Spagna,
R. J. Appl. Crystallogr. 2005, 38, 381.
(35) Beurskens, P. T.; Admiraal, G.; Beurskens, G.; Bosman, W. P.;
Garcıa-Granda, S.; Gould, R. O.; Smits, J. M. M.; Smykalla, C. The
DIRDIF Program System; Technical Report of the Crystallographic
Laboratory; University of Nijmegen: Nijmegen, The Netherlands, 1999.
(36) Sheldrick, G. M. SHELXL97, Program for the Refinement of
(37) International Tables for X-Ray Crystallography; Kynoch Press:
Birminghan, U.K., 1974; Vol. IV (Present distributor: Kluwer Academic
Publishers; Dordrecht, The Netherlands).
(38) Nardelli, M. Comput. Chem. 1983, 7, 95.
(39) Spek, A. L. PLATON: A Multipurpose Crystallographic Tool;
University of Utrecht: Utrecht, The Netherlands, 2007.
€
€
Crystal Structures; University of Gottingen: Gottingen, Germany, 1997.