Ruthenium(II) and ruthenium(IV) complexes containing κ1-P-, κ2-P,O-, and κ3-P,N,O-iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R = Et, Ph): Synthesis, reactivity, theoretical studies, and catalytic activity in transfer hydrogenation of cyclohexanone

Inorg. Chem. 2003, 42, 3293−3307

Ruthenium(II) and Ruthenium(IV) Complexes Containing K¹-P-, K²-P,O-,

and K³-P,N,O-Iminophosphorane-Phosphine Ligands

Ph₂PCH P{dNP(dO)(OR)₂}Ph₂(R ) Et, Ph): Synthesis, Reactivity,

2

Theoretical Studies, and Catalytic Activity in Transfer Hydrogenation of

Cyclohexanone

Victorio Cadierno, Pascale Crochet, Josefina D´ıez, Joaqu´ın Garc´ıa-AÄ lvarez,

,†

Sergio E. Garc´ıa-Garrido, and Jose´ Gimeno*

Departamento de Qu´ımica Orga´nica e Inorga´nica, Instituto UniVersitario de Qu´ımica

Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC), Facultad de Qu´ımica,

UniVersidad de OViedo, E-33071 OViedo, Spain

Santiago Garc´ıa-Granda

Departamento de Qu´ımica F´ısica y Anal´ıtica, Facultad de Qu´ımica, UniVersidad de OViedo,

E-33071 OViedo, Spain

,‡

Miguel A. Rodr´ıguez*

Departamento de Qu´ımica, UniVersidad de La Rioja, Grupo de S´ıntesis Qu´ımica de La Rioja

(Unidad Asociada al CSIC), Madre de Dios 51, E-26006 Logron˜o, Spain

Received December 3, 2002

[{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂] and [{Ru(η³:η³-C H )(µ-Cl)Cl}₂] react with Ph₂PCH P{dNP(dO)(OR)₂}Ph₂(R )

10 16

2

Et (1a), Ph (1b)) affording complexes [Ru(η⁶-p-cymene)Cl₂(κ¹-P-Ph₂PCH P{dNP(dO)(OR)₂}Ph₂)] (R ) Et (2a),

2

Ph (2b)) and [Ru(η³:η³-C H )Cl₂(κ¹-P-Ph₂PCH P{dNP(dO)(OR)₂}Ph₂)] (R ) Et (6a), Ph (6b)). While treatment

10 16

2

of 2a with 1 equiv of AgSbF yields a mixture of [Ru(η⁶-p-cymene)Cl(κ²-P,O-Ph₂PCH P{dNP(dO)(OEt)₂}Ph₂)]-

6

2

[SbF ] (3a) and [Ru(η⁶-p-cymene)Cl(κ²-P,N-Ph₂PCH P{dNP(dO)(OEt)₂}Ph₂)][SbF ] (4a), [Ru(η⁶-p-cymene)Cl(κ²-

6

2

6

P,O-Ph₂PCH P{dNP(dO)(OPh)₂}Ph₂)][SbF ] (3b) and [Ru(η³:η³-C H )Cl(κ²-P,O-Ph₂PCH P{dNP(dO)(OR)₂}-

2

6

10 16

2

Ph₂)][SbF ] (R ) Et (7a), Ph (7b)) are selectively formed from 2b and 6a,b. Complexes [Ru(η⁶-p-cymene)(κ³-

6

P,N,O-Ph PCH P{dNP(dO)(OR)₂}Ph )][SbF ] (R ) Et (5a), Ph (5b)) and [Ru(η³:η³-C H )(κ³-P,N,O-Ph PCH P{d

2

6 2

10 16

2

NP(dO)(OR)₂}Ph₂)][SbF ] (R ) Et (8a), Ph (8b)) have been prepared using 2 equiv of AgSbF . The reactivity of

6 2

6

3−5a,b has been explored allowing the synthesis of [Ru(η⁶-p-cymene)X (κ¹-P-Ph₂PCH P{dNP(dO)(OR)₂}Ph₂)]

2

(R ) Et, Ph; X ) Br, I, N , NCO (9−12a,b)). The catalytic activity of 2−8a,b in transfer hydrogenation of

3

cyclohexanone, as well as theoretical calculations on the models [Ru(η⁶-C H )Cl(κ²-P,N-H PCH P{dNP(dO)-

6

2

(OH)₂}H )]⁺and [Ru(η⁶-C H )Cl(κ²-P,O-H PCH P{dNP(dO)(OH)₂}H )]⁺, has been also studied.

2

6

2

Introduction

atom and a hemilabile donor group (i.e. N- or O-donor)

capable of reversibly dissociating from the metal liberating

a coordination site.¹Such behavior has been exploited in

homogeneous catalysis since the formation of unsaturated

intermediate species is often favored.¹Iminophosphorane-

phosphines R₂P-XsP(dNR′)R₂(readily accessible by se-

lective monoimination of bis-phosphines with azides via the

There is a considerable interest in the coordination

chemistry of phosphine ligands with hemilabile properties

because they combine strong binding via the phosphorus

^†E-mail: jgh@sauron.quimica.uniovi.es.

^‡E-mail: miguelangel.rodriguez@dq.unirioja.es.

Published on Web 04/16/2003

Inorganic Chemistry, Vol. 42, No. 10, 2003 3293

Cadierno et al.

Chart 1

Chart 2

catalytic transformations,⁶in this paper we report the

synthesis of the novel iminophosphorane-phosphines Ph₂-

PCH₂P{dNP(dO)(OR)₂}Ph₂(R ) Et (1a), Ph (1b)) con-

taining a coordinating phosphoryl substituent. Our interest

stems from the expected hemilabile properties and its

potential coordination versatility since bidentate chelating

modes κ²-P,N- (II) and κ²-P,O- (III) as well as tridentate

κ³-P,N,O- behavior (IV) can be envisaged (see Chart 2).⁷

Starting from the ruthenium(II) and ruthenium(IV) dimers

[{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂] and [{Ru(η³:η³-C₁₀H₁₆)(µ-Cl)-

Cl}₂] (C₁₀H₁₆) 2,7-dimethylocta-2,6-diene-1,8-diyl), re-

spectively, here we describe that the tridentate ligands 1a,b

can be coordinated selectively in κ¹-P-, κ²-P,O-, and κ³-

P,N,O-manners (I, III, and IV in Chart 2). The hemilabile

properties of the chelate complexes and their catalytic activity

in transfer hydrogenation of cyclohexanone by propan-2-ol

have been also explored.⁸In addition, a theoretical study

devoted to rationalize the competitive ability of the ligands

for the formation of a five- versus seven-membered chelate

ring (κ²-P,N- (II) vs κ²-P,O- (III)) is described using the

models [Ru(η⁶-C₆H₆)Cl(κ²-P,O-H₂PCH₂P{dNP(dO)(OH)₂}-

H₂)]⁺and [Ru(η⁶-C₆H₆)Cl(κ²-P,N-H₂PCH₂P{dNP(dO)-

(OH)₂}H₂)]⁺.

Staudinger reaction)^2,3are an important class of hemilabile

ligands belonging to the wide series of those containing

phosphorus-nitrogen donor atoms.⁴In this context, we have

recently reported the preparation of the first ruthenium

complexes bearing iminophosphorane-phosphine ligands (see

Chart 1) which show excellent hemilabile properties.⁵

Following these studies, and because the chemistry of the

closely related bis-phosphine monoxides (BPMOs) of general

formula R₂P-XsP(dO)R₂(X ) divalent bridging group)

has revealed successful applications in a large number of

(1) For reviews on hemilabile P,N- and P,O-donor ligands see: (a) Bader,

A.; Lindner, E. Coord. Chem. ReV. 1991, 108, 27. (b) Newkome, G.

R. Chem. ReV. 1993, 93, 2067. (c) Zhang, Z. Z.; Cheng, H. Coord.

Chem. ReV. 1996, 147, 1. (d) Lindner, E.; Pautz, S.; Haustein, M.

Coord. Chem. ReV. 1996, 155, 145. (e) Espinet, P.; Soulantica, K.

Coord. Chem. ReV. 1999, 193-195, 499. (f) Slone, C. S.; Weinberger,

D. A.; Mirkin, C. A. Prog. Inorg. Chem. 1999, 48, 233. (g) Braunstein,

P.; Naud, F. Angew. Chem., Int. Ed. 2001, 40, 680.

(2) For reviews on the Staudinger reaction see: (a) Gololobov, Y. G.;

Zhmurova, I. N.; Kasukhin, L. F. Tetrahedron 1981, 37, 437. (b)

Gololobov, Y. G.; Kasukhin, L. F. Tetrahedron 1992, 48, 1353. (c)

Johnson, A. W. In Ylides and Imines of Phosphorus; Wiley: New

York, 1993; p 403.

(3) Selective monoiminations of bis-phosphines are reported in the

following: (a) Gilyarov, V. A.; Kovtum, V. Y.; Kabachmich, M. I.

IzV. Akad. Nauk SSSR, Ser. Khim. 1967, 5, 1159. (b) Katti, K. V.;

Cavell, R. G. Inorg. Chem. 1989, 28, 413. (c) Katti, K. V.; Batchelor,

R. J.; Einstein, F. W. B.; Cavell, R. G. Inorg. Chem. 1990, 29, 808.

(d) Cavell, R. G.; Reed, R. W.; Katti, K. V.; Balakrishna, M. S.;

Collins, P. W.; Mozol, V.; Bartz, I. Phosphorus, Sulfur Silicon Relat.

Elem. 1993, 76, 9. (e) Balakrishna, M. S.; Santarsiero, B. D.; Cavell,

R. G. Inorg. Chem. 1994, 33, 3079. (f) Reed, R. W.; Santarsiero, B.;

Cavell, R. G. Inorg. Chem. 1996, 35, 4292. (g) Avis, M. W.; Goosen,

M.; Elsevier, C. J.; Veldman, N.; Kooijman, H.; Spek, A. L. Inorg.

Chim. Acta 1997, 264, 43. (h) Molina, P.; Arques, A.; Garc´ıa A.;

Ram´ırez de Arellano, M. C. Tetrahedron Lett. 1997, 38, 7613. (i)

Molina, P.; Arques, A.; Garc´ıa, A.; Ram´ırez de Arellano, M. C. Eur.

J. Inorg. Chem. 1998, 1359. (j) Pandurangi, R. S.; Katti, K. V.;

Stillwell, L.; Barnes, C. L. J. Am. Chem. Soc. 1998, 120, 11364. (k)

Alajar´ın, M.; Lo´pez-Leonardo, C.; Llamas-Lorente, P.; Bautista, D.

Synthesis 2000, 2085. (l) Arques, A.; Molina, P.; Aun˜on, D.; Vilaplana,

M. J.; Desamparados Velasco, M.; Mart´ınez, F.; Bautista, D.; Lahoz,

F. J. J. Organomet. Chem. 2000, 598, 329. (m) Balakrishna, M. S.;

Teipel, S.; Pinkerton, A. A.; Cavell, R. G. Inorg. Chem. 2001, 40,

1802.

Experimental Section

The manipulations were performed under an atmosphere of dry

nitrogen using vacuum-line and standard Schlenk techniques.

Solvents were dried by standard methods and distilled under

(6) See for example: Grushin, V. V. Organometallics 2001, 20, 3950

and references therein.

(7) The related ligands Ph₂PN(R)P{dNP(dO)(OPh)₂}Ph₂(R ) Me, Et)

and 2-Ph₂PC₆H₄P{dNP(dO)(OPh)₂}Ph₂have been described by R.

G. Cavell and co-workers. Remarkably, its complexation to Rh(I),

Pd(II), and Pt(II) fragments leads exclusively to the bidentate κ²-P,N-

coordination. See ref 3e,f.

(8) Although several transition-metal complexes containing iminophos-

phorane-phosphine ligands are known (see refs 3 and 4), their

involvement in homogeneous catalysis has been almost neglected when

compared to their BPMO counterparts. Hydrogenation of olefins (Rh

and Ir complexes): (a) Law, D. J.; Cavell, R. G. J. Mol. Catal. 1994,

91, 175. (b) Cavell, R. G.; Law, D. J.; Reed, R. W. U.S. Patent

Application US 887014, 1994. Methanol carbonylation (Rh, Ni, and

Co complexes): (c) Cavell, R. G.; Katti, K. V. U.S. Patent Application

US 752348, 1994. Olefin oligomerization (Ni complexes): (d) Cavell,

R. G.; Creed, B.; Gelmini, L.; Law, D. J.; McDonald, R.; Sanger, A.

R.; Somogyvary, A. Inorg. Chem. 1998, 37, 757. (e) Cavell, R. G.;

Creed, B.; Law, D. J.; Nicola, A. P.; Sanger, A. R.; Somogyvary, A.

U.S. Patent Application US 447887, 1996. Cross coupling of secondary

amines with aryl halides (Pd complexes): ref 3h.

(4) For overviews on the coordination chemistry of R₂PsXsP(dNR′)-

R₂ligands see: (a) Katti, K. V.; Cavell, R. G. Comments Inorg. Chem.

1990, 10, 53. (b) Cavell, R. G. Curr. Sci. 2000, 78, 440.

(5) (a) Cadierno, V.; D´ıez, J.; Garc´ıa-Garrido, S. E.; Garc´ıa-Granda, S.;

Gimeno, J. J. Chem. Soc., Dalton Trans. 2002, 1465. (b) Cadierno,

V.; Crochet, P.; Garc´ıa-AÄ lvarez, J.; Garc´ıa-Garrido, S. E.; Gimeno, J.

J. Organomet. Chem. 2002, 663, 32.

3294 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

nitrogen before use. All reagents were obtained from commercial

suppliers and used without further purification with the exception

of compounds [{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂],⁹[{Ru(η³:η³-C₁₀H₁₆)-

(µ-Cl)Cl}₂],¹⁰and (EtO)₂P(dO)N₃,¹¹which were prepared by

following the methods reported in the literature. Infrared spectra

were recorded on a Perkin-Elmer 1720-XFT spectrometer. The

conductivities were measured at room temperature, in ca. 10^-3mol

dm^-3acetone solutions, with a Jenway PCM3 conductimeter. The

C, H, and N analyses were carried out with a Perkin-Elmer 2400

microanalyzer. All melting points were determined on a Bu¨chi CH-

9230 oil-based apparatus and are uncorrected. Mass spectra

(MALDI-TOF) were recorded using a VOYAGER-DE STR

spectrometer; R-cyano-4-hydroxycinnamic acid was used as the

matrix. NMR spectra were recorded on a Bruker DPX-300

instrument at 300 MHz (¹H), 121.5 MHz (³¹P), or 75.4 MHz (¹³C)

using SiMe₄or 85% H₃PO₄as standards. DEPT experiments have

been carried out for all the compounds reported. ³¹P{¹H} NMR

spectroscopic data for all the compounds reported are collected in

Table 2.

cymene)(µ-Cl)Cl}₂] (0.245 g, 0.4 mmol) and the corresponding

iminophosphorane-phosphine Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂(1a,b)

(0.85 mmol) in 30 mL of dichloromethane was stirred at room

temperature for 1 h. The resulting solution was then concentrated

to ca. 2 mL, and 50 mL of diethyl ether was added yielding a

microcrystalline orange solid which was washed with diethyl ether

(3 × 10 mL) and vacuum-dried. For 2a: yield 81% (0.545 g), mp

194-196 °C. Anal. Calcd for RuC₃₉H₄₆O₃P₃Cl₂N‚1/4CH₂Cl₂: C,

1

54.63; H, 5.43; N, 1.62. Found: C, 54.50; H, 5.39; N, 1.67. H

NMR (CDCl₃) δ 0.79 (d, 6H, J_HH) 6.8 Hz, CH(CH₃)₂), 0.99 (t,

6H, J_HH) 6.6 Hz, OCH₂CH₃), 1.74 (s, 3H, CH₃), 2.34 (sept, 1H,

J_HH) 6.8 Hz, CH(CH₃)₂), 3.45 (m, 4H, OCH₂), 3.87 (dd, 2H, ²J_HP

) 9.1 and 9.1 Hz, PCH₂P), 5.05 and 5.20 (d, 2H each, J_HH) 5.0

Hz, CH of p-cymene), 7.30-8.01 (m, 20H, Ph). ¹³C{¹H} NMR

3

(CDCl₃) δ 16.46 (d, J_CP) 9.0 Hz, OCH₂CH₃), 17.41 (s, CH₃),

21.40 (ddd, J_CP) 78.6 and 19.2 Hz, ³J_CP) 8.4 Hz, PCH₂P), 21.46

2

(s, CH(CH₃)₂), 30.38 (s, CH(CH₃)₂), 61.03 (d, J_CP) 6.8 Hz,

OCH₂), 86.06 (d, ²J_CP) 6.8 Hz, CH of p-cymene), 90.58 (d, ²J_CP

) 4.1 Hz, CH of p-cymene), 94.73 and 108.28 (s, C of p-cymene),

128.17-134.49 (m, Ph) ppm. For 2b: yield 73% (0.547 g), mp

222-224 °C. Anal. Calcd for RuC₄₇H₄₆O₃P₃Cl₂N: C, 60.19; H,

4.94; N, 1.49. Found: C, 60.26; H, 4.81; N, 1.52. ¹H NMR (CDCl₃)

δ 0.78 (d, 6H, J_HH) 6.9 Hz, CH(CH₃)₂), 1.77 (s, 3H, CH₃), 2.38

(sept, 1H, J_HH) 6.9 Hz, CH(CH₃)₂), 3.98 (dd, 2H, ²J_HP) 9.9 and

9.9 Hz, PCH₂P), 5.06 and 5.21 (d, 2H each, J_HH) 6.0 Hz, CH of

p-cymene), 7.04-7.91 (m, 30H, Ph). ¹³C{¹H} NMR (CDCl₃) δ

The numbering for protons and carbons of the 2,7-dimethylocta-

2,6-diene-1,8-diyl skeleton is as follows:

3

17.49 (s, CH₃), 20.43 (ddd, J_CP) 79.4 and 18.1 Hz, J_CP) 6.4

Hz, PCH₂P), 21.39 (s, CH(CH₃)₂), 30.43 (s, CH(CH₃)₂), 86.20 (d,

2

²J_CP) 6.4 Hz, CH of p-cymene), 90.70 (d, J_CP) 4.7 Hz, CH of

p-cymene), 96.40 and 108.28 (s, C of p-cymene), 120.63-134.44

2

(m, Ph), 152.69 (d, J_CP) 7.6 Hz, C_ipsoof OPh) ppm.

Synthesis of Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂(R ) Et (1a), Ph

(1b)). The corresponding azide (RO)₂P(dO)N₃(5.2 mmol) was

added at -78 °C to a solution of bis(diphenylphosphino)methane

(2 g, 5.2 mmol) in 80 mL of THF. The reaction mixture was slowly

warmed to room temperature and then evaporated to dryness to

give a colorless oil. A microcrystalline white solid was obtained

by slow diffusion of pentane into a saturated dichloromethane

solution of the product at room temperature. Characterization data

for 1a follow: yield 93% (2.589 g), mp 148-150 °C. Anal. Calcd

for C₂₉H₃₂O₃P₃N: C, 65.04; H, 6.02; N, 2.61. Found: C, 65.12;

Synthesis of [Ru(η⁶-p-cymene)Cl(K²-P,O-Ph₂PCH₂P{dNP(d

O)(OR)₂}Ph₂)][SbF₆] (R ) Et (3a), Ph (3b)) and [Ru(η⁶-p-

cymene)Cl(K²-P,N-Ph₂PCH₂P{dNP(dO)(OEt)₂}Ph₂)][SbF₆] (4a).

Method A. A solution of the corresponding neutral complex

[Ru(η⁶-p-cymene)Cl₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] (2a,b)

(0.5 mmol) in 50 mL of dichloromethane was treated, at room

temperature and in the absence of light, with AgSbF₆(0.172 g, 0.5

mmol) for 1 h. After the AgCl formed was filtered off (Kieselguhr),

the solution was concentrated to ca. 2 mL, and 50 mL of diethyl

ether was then added yielding an orange microcrystalline solid

which was washed with diethyl ether (3 × 20 mL) and vacuum-

dried. Starting from 2a, an inseparable mixture containing com-

pounds 3a and 4a (ca. 3:1 ratio) was obtained in 85% yield (0.443

g). Mp: 178-180 °C (dec). Anal. Calcd for RuC₃₉H₄₆F₆O₃P₃-

ClNSb‚1/4CH₂Cl₂: C, 44.34; H, 4.41; N, 1.32. Found: C, 44.18;

H, 4.21; N, 1.30. Conductivity (acetone, 20 °C, Ω^-1cm²mol^-1):

1

H, 5.89; N, 2.76. H NMR (CDCl₃) δ 1.19 (t, 6H, J_HH) 7.1 Hz,

2

OCH₂CH₃), 3.46 (d, 2H, J_HP) 13.9 Hz, PCH₂P), 3.95 (m, 4H,

OCH₂), 7.21-7.77 (m, 20H, Ph) ppm. ¹³C{¹H} NMR (CDCl₃) δ

3

16.29 (d, J_CP) 7.9 Hz, OCH₂CH₃), 29.81 (dd, J_CP) 64.4 and

33.9 Hz, PCH₂P), 61.42 (d, ²J_CP) 6.8 Hz, OCH₂), 128.26-132.90

3

(m, Ph), 137.62 (dd, J_CP) 22.6 Hz, J_CP) 7.9 Hz, C_ipsoof Ph)

ppm. MS (MALDI-TOF): m/z 536 [M + 1]⁺. For 1b: yield 86%

(2.824 g), mp 107-109 °C. Anal. Calcd for C₃₇H₃₂O₃P₃N: C,

1

115. For 3a: H NMR (CD₂Cl₂) δ 0.96 and 1.17 (d, 3H each, J_HH

) 6.8 Hz, CH(CH₃)₂), 1.13 and 1.35 (t, 3H each, J_HH) 7.0 Hz,

OCH₂CH₃), 1.73 (s, 3H, CH₃), 2.23 (m, 1H, CH(CH₃)₂), 3.09 and

5.17 (m, 1H each, PCH₂P), 3.63-4.15 (m, 4H, OCH₂), 4.92 and

5.40 (d, 1H each, J_HH) 5.4 Hz, CH of p-cymene), 5.79 and 5.98

1

70.36; H, 5.11; N, 2.22. Found: C, 70.20; H, 5.01; N, 2.30. H

NMR (CDCl₃) δ 3.36 (d, 2H, ²J_HP) 13.7 Hz, PCH₂P), 7.06-7.62

(m, 30H, Ph) ppm. ¹³C{¹H} NMR (CDCl₃) δ 29.76 (dd, J_CP

)

65.3 and 34.1 Hz, PCH₂P), 120.20-134.23 (m, Ph), 138.99 (dd,

(d, 1H each, J_HH) 6.0 Hz, CH of p-cymene), 7.05-8.00 (m, 20H,

3

2

J_CP) 14.9 Hz, J_CP) 7.8 Hz, C_ipsoof Ph), 152.22 (d, J_CP) 7.8

Hz, C_ipsoof OPh) ppm. MS (MALDI-TOF): m/z 632 [M + 1]⁺.

Synthesis of [Ru(η⁶-p-cymene)Cl₂(K¹-P-Ph₂PCH₂P{dNP(d

O)(OR)₂}Ph₂)] (R ) Et (2a), Ph (2b)). A solution of [{Ru(η⁶-p-

Ph) ppm. ¹³C{¹H} NMR (CD₂Cl₂) δ 16.10 and 16.50 (d, J_CP

)

3

8.2 Hz, OCH₂CH₃), 17.73 (s, CH₃), 21.70 and 22.24 (s, CH(CH₃)₂),

28.97 (dd, J_CP) 56.5 and 15.7 Hz, PCH₂P), 30.76 (s, CH(CH₃)₂),

2

63.43 and 63.54 (d, J_CP) 7.0 Hz, OCH₂), 84.06 (d, J_CP) 4.1

Hz, CH of p-cymene), 88.06 (d, ²J_CP) 5.7 Hz, CH of p-cymene),

(9) Bennett, M. A.; Huang, T.-N.; Matheson, T. W.; Smith, A. K. Inorg.

Synth. 1982, 21, 74.

(10) (a) Porri, L.; Gallazzi, M. C.; Colombo, A.; Allegra, G. Tetrahedron

Lett. 1965, 47, 4187. (b) Salzer, A.; Bauer, A.; Podewils, F. In Synthetic

Methods of Organo-metallic and Inorganic Chemistry; Herrmann, W.

A., Ed.; Thieme Verlag: Stuttgart, 2000; Vol. 9, p 36.

2

88.50 (d, J_CP) 2.3 Hz, CH of p-cymene), 90.36 (d, J_CP) 5.3

Hz, CH of p-cymene), 97.53 and 107.96 (s, C of p-cymene),

1

124.31-137.12 (m, Ph) ppm. For 4a: H NMR (CD₂Cl₂) δ 0.80

and 1.01 (d, 3H each, J_HH) 6.8 Hz, CH(CH₃)₂), 0.93 and 1.25 (t,

3H each, J_HH) 7.0 Hz, OCH₂CH₃), 1.93 (s, 3H, CH₃), 3.46 (m,

(11) Scott, F. L.; Riordan, R.; Morton, P. D. J. Org. Chem. 1962, 27, 4255.

Inorganic Chemistry, Vol. 42, No. 10, 2003 3295

Cadierno et al.

1H, CH(CH₃)₂), 3.63-4.15 (m, 6H, PCH₂P and OCH₂), 5.69 and

5.96 (d, 1H each, J_HH) 5.4 Hz, CH of p-cymene), 5.86 (br, 2H,

CH of p-cymene), 7.05-8.00 (m, 20H, Ph) ppm. ¹³C{¹H} NMR

Anal. Calcd for RuC₄₇H₄₆F₁₂O₃P₃Sb₂N: C, 42.18; H, 3.16; N, 1.05.

Found: C, 41.87; H, 3.02; N, 1.12. Conductivity (acetone, 20 °C,

1

Ω^-1cm²mol^-1): 184. H NMR (CD₂Cl₂) δ 1.04 (d, 3H, J_HH

)

3

(CD₂Cl₂) δ 16.01 (d, J_CP) 6.4 Hz, OCH₂CH₃), 16.30 (d, J_CP

)

6.8 Hz, CH(CH₃)₂), 1.29 (d, 3H, J_HH) 6.5 Hz, CH(CH₃)₂), 1.43

(s, 3H, CH₃), 2.25 (m, 1H, CH(CH₃)₂), 2.78 and 4.00 (m, 1H each,

PCH₂P), 5.32 (br, 2H, CH of p-cymene), 6.29 and 6.45 (br, 1H

each, CH of p-cymene), 6.95-7.99 (m, 30H, Ph) ppm. ¹³C{¹H}

NMR (CD₂Cl₂) δ 15.77 (s, CH₃), 21.37 and 23.33 (s, CH(CH₃)₂),

27.23 (ddd, J_CP) 63.1 and 13.0 Hz, ³J_CP) 7.2 Hz, PCH₂P), 32.05

(s, CH(CH₃)₂), 81.10 and 85.46 (s, CH of p-cymene), 87.11 and

89.50 (d, ²J_CP) 5.5 Hz, CH of p-cymene), 98.59 and 113.52 (s, C

8.1 Hz, OCH₂CH₃), 18.06 (s, CH₃), 20.65 and 23.35 (s, CH(CH₃)₂),

3

29.69 (s, CH(CH₃)₂), 36.74 (ddd, J_CP) 75.4 and 16.7 Hz, J_CP

)

8.2 Hz, PCH₂P), 63.73 (d, ²J_CP) 7.0 Hz, OCH₂), 63.82 (d, ²J_CP

2

6.4 Hz, OCH₂), 82.45 (s, CH of p-cymene), 87.02 (d, J_CP) 4.1

Hz, CH of p-cymene), 87.15 (d, ²J_CP) 5.3 Hz, CH of p-cymene),

2

91.31 (d, J_CP) 5.1 Hz, CH of p-cymene), 106.72 and 113.68 (s,

C of p-cymene), 124.31-137.12 (m, Ph) ppm. For 3b: yield 86%

(0.489 g), mp 188-190 °C (dec). Anal. Calcd for RuC₄₇H₄₆F₆O₃P₃-

ClNSb: C, 49.60; H, 4.07; N, 1.23. Found: C, 50.05; H, 3.93; N,

1.31. Conductivity (acetone, 20 °C, Ω^-1cm²mol^-1): 102. ¹H NMR

(CD₂Cl₂) δ 0.85 (d, 3H, J_HH) 6.8 Hz, CH(CH₃)₂), 1.10 (d, 3H,

J_HH) 6.6 Hz, CH(CH₃)₂), 1.64 (s, 3H, CH₃), 2.17 (m, 1H,

CH(CH₃)₂), 3.15 and 5.16 (m, 1H each, PCH₂P), 4.60 and 5.29 (d,

1H each, J_HH) 5.7 Hz, CH of p-cymene), 5.07 and 5.75 (d, 1H

each, J_HH) 6.2 Hz, CH of p-cymene), 6.85-7.64 (m, 30H, Ph)

ppm. ¹³C{¹H} NMR (CD₂Cl₂) δ 17.76 (s, CH₃), 21.45 and 22.22

(s, CH(CH₃)₂), 28.27 (dd, J_CP) 57.1 and 15.8 Hz, PCH₂P), 30.66

(s, CH(CH₃)₂), 83.43 and 87.96 (s, CH of p-cymene), 88.84 (d,

2

of p-cymene), 120.15-135.70 (m, Ph), 151.06 (d, J_CP) 9.0 Hz,

2

C_ipsoof OPh), 151.63 (d, J_CP) 9.0 Hz, C_ipsoof OPh) ppm.

Method B. A solution containing [Ru(η⁶-p-cymene)Cl(κ²-P,O-

Ph₂PCH₂P{dNP(dO)(OPh)₂}Ph₂)][SbF₆] (3b), or a mixture of

[Ru(η⁶-p-cymene)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OEt)₂}Ph₂)]-

[SbF₆] (3a) and [Ru(η⁶-p-cymene)Cl(κ²-P,N-Ph₂PCH₂P{dNP-

(dO)(OEt)₂}Ph₂)][SbF₆] (4a), (0.2 mmol) in 20 mL of dichloro-

methane was treated, at room temperature and in the absence of

light, with AgSbF₆(0.072 g, 0.21 mmol) for 1 h. After the excess

of AgSbF₆used and the AgCl formed were filtered off (Kieselguhr),

the solution was concentrated to ca. 2 mL, and 30 mL of diethyl

ether was then added yielding an orange microcrystalline solid

which was washed with diethyl ether (3 × 10 mL) and vacuum-

dried. For 5a: yield: 87% (0.216 g). For 5b: yield: 80% (0.214

g).

2

²J_CP) 6.4 Hz, CH of p-cymene), 90.83 (d, J_CP) 5.3 Hz, CH of

p-cymene), 97.91 and 108.10 (s, C of p-cymene), 120.93-135.64

(m, Ph), 151.74 (d, ²J_CP) 8.7 Hz, C_ipsoof OPh), 151.85 (d, ²J_CP

)

7.6 Hz, C_ipsoof OPh) ppm.

Method B. A suspension of [{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂]

(0.122 g, 0.2 mmol), the corresponding iminophosphorane-phos-

phine 1a,b (0.43 mmol), and AgSbF₆(0.137 g, 0.4 mmol) in 30

mL of dichloromethane was stirred, at room temperature and in

the absence of light, for 1.5 h. After the AgCl formed was filtered

off (Kieselguhr), the solution was concentrated to ca. 2 mL, and

30 mL of diethyl ether was then added yielding an orange

microcrystalline solid which was washed with diethyl ether (3 ×

10 mL) and vacuum-dried. For 3a/4a: yield 82% (0.342 g). For

3b: yield 83% (0.378 g).

Synthesis of [Ru(η³:η³-C₁₀H₁₆)Cl₂(K¹-P-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)] (R ) Et (6a), Ph (6b)). Complexes 6a,b, isolated

as orange microcrystalline solids, were prepared as described for

2a,b starting from [{Ru(η³:η³-C₁₀H₁₆)(µ-Cl)Cl}₂] (0.246 g, 0.4

mmol) and the corresponding iminophosphorane-phosphine 1a,b

(0.85 mmol). For 6a: yield: 97% (0.655 g), mp 96-98 °C. Anal.

Calcd for RuC₃₉H₄₈O₃P₃Cl₂N: C, 55.52; H, 5.73; N, 1.66. Found:

C, 55.67; H, 5.59; N, 1.78. ¹H NMR (CDCl₃) δ 1.05 (t, 6H, J_HH

)

7.0 Hz, OCH₂CH₃), 2.12 (s, 6H, CH₃), 2.64 (m, 2H, H₄and H₆),

3.22 (d, 2H, J_HP) 3.1 Hz, H₂and H₁₀), 3.48 (m, 6H, OCH₂, H₅

3

and H₇), 3.94 and 4.23 (m, 1H each, PCH₂P), 4.20 (d, 2H, ³J_HP

)

Synthesis of [Ru(η⁶-p-cymene)(K³-P,N,O-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)][SbF₆]₂(R ) Et (5a), Ph (5b)). Method A. A

solution of the corresponding neutral complex [Ru(η⁶-p-cymene)-

Cl₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] (2a,b) (0.5 mmol) in

50 mL of dichloromethane was treated, at room temperature and

in the absence of light, with AgSbF₆(0.378 g, 1.1 mmol) for 1 h.

After the excess of AgSbF₆used and the AgCl formed were filtered

off (Kieselguhr), the solution was concentrated to ca. 2 mL, and

50 mL of diethyl ether was then added yielding an orange

microcrystalline solid which was washed with diethyl ether (3 ×

20 mL) and vacuum-dried. For 5a: yield 93% (0.577 g), mp 139-

141 °C (dec). Anal. Calcd for RuC₃₉H₄₆F₁₂O₃P₃Sb₂N: C, 37.71;

H, 3.73; N, 1.13. Found: C, 37.59; H, 3.82; N, 1.09. Conductivity

(acetone, 20 °C, Ω^-1cm²mol^-1): 198. ¹H NMR (CD₂Cl₂) δ 0.68

and 1.15 (t, 3H each, J_HH) 6.8 Hz, OCH₂CH₃), 0.95 and 1.22 (d,

3H each, J_HH) 6.8 Hz, CH(CH₃)₂), 1.40 (s, 3H, CH₃), 2.45 (m,

1H, CH(CH₃)₂), 3.45 and 3.88 (m, 2H each, OCH₂), 4.78 and 5.02

(m, 1H each, PCH₂P), 5.78 and 6.55 (d, 1H each, J_HH) 5.0 Hz,

CH of p-cymene), 5.91 and 6.30 (d, 1H each, J_HH) 5.5 Hz, CH of

p-cymene), 7.03-8.33 (m, 20H, Ph) ppm. ¹³C{¹H} NMR (CD₂-

Cl₂) δ 14.33 and 15.87 (br, OCH₂CH₃), 16.21 (s, CH₃), 20.58 and

22.40 (s, CH(CH₃)₂), 26.69 (dd, J_CP) 66.4 and 17.9 Hz, PCH₂P),

9.8 Hz, H₁and H₉), 5.16 (m, 2H, H₃and H₈), 7.00-7.90 (m, 20H,

Ph). ¹³C{¹H} NMR (CDCl₃) δ 16.47 (d, ³J_CP) 7.8 Hz, OCH₂CH₃),

3

20.87 (s, CH₃), 24.98 (ddd, J_CP) 74.7 and 16.2 Hz, J_CP) 7.0

Hz, PCH₂P), 36.88 (s, C₄and C₅), 61.24 (d, ²J_CP) 6.2 Hz, OCH₂),

68.51 (d, ²J_CP) 4.9 Hz, C₁and C₈), 107.87 (d, ²J_CP) 10.3 Hz, C₃

and C₆), 125.92 (s, C₂and C₇), 127.00-135.00 (m, Ph) ppm. For

6b: yield 86% (0.646 g), mp 160-162 °C. Anal. Calcd for

RuC₄₇H₄₈O₃P₃Cl₂N: C, 60.07; H, 5.15; N, 1.49. Found: C, 60.21;

H, 4.70; N, 1.34. ¹H NMR (CDCl₃) δ 2.13 (s, 6H, CH₃), 2.63 (m,

2H, H₄and H₆), 3.24 (d, 2H, ³J_HP) 3.4 Hz, H₂and H₁₀), 3.45 (m,

2H, H₅and H₇), 3.95 and 4.23 (m, 1H each, PCH₂P), 4.22 (d, 2H,

³J_HP) 9.4 Hz, H₁and H₉), 5.18 (m, 2H, H₃and H₈), 6.85-7.70

(m, 30H, Ph). ¹³C{¹H} NMR (CDCl₃) δ 20.86 (s, CH₃), 24.75 (ddd,

J_CP) 74.9 and 15.2 Hz, ³J_CP) 6.6 Hz, PCH₂P), 36.89 (s, C₄and

C₅), 68.40 (d, ²J_CP) 5.4 Hz, C₁and C₈), 108.01 (d, ²J_CP) 9.9 Hz,

C₃and C₆), 120.56-134.82 (m, Ph), 125.96 (s, C₂and C₇), 152.71

2

(d, J_CP) 7.2 Hz, C_ipsoof OPh) ppm.

Synthesis of [Ru(η³:η³-C₁₀H₁₆)Cl(K²-P,O-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)][SbF₆] (R ) Et (7a), Ph (7b)). Complexes 7a,b,

isolated as orange microcrystalline solids, were prepared as

described for 3a,b starting either from [Ru(η³:η³-C₁₀H₁₆)Cl₂(κ¹-P-

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] (6a,b) (0.5 mmol) (method A)

or [{Ru(η³:η³-C₁₀H₁₆)(µ-Cl)Cl}₂] (0.123 g, 0.2 mmol) (method B).

For 7a: yield (method A) 91% (0.475 g), yield (method B) 88%

(0.367 g); mp 130-132 °C (dec). Anal. Calcd for RuC₃₉H₄₈F₆O₃P₃-

ClNSb‚1/4CH₂Cl₂: C, 44.26; H, 4.59; N, 1.31. Found: C, 44.40;

2

31.95 (s, CH(CH₃)₂), 67.03 (d, J_CP) 9.0 Hz, OCH₂), 68.03 (d,

²J_CP) 4.9 Hz, OCH₂), 76.09 and 91.60 (s, CH of p-cymene), 88.27

(d, ²J_CP) 9.1 Hz, CH of p-cymene), 94.30 (d, ²J_CP) 10.8 Hz, CH

of p-cymene), 99.93 and 113.33 (s, C of p-cymene), 120.86-136.28

(m, Ph) ppm. For 5b: yield 77% (0.515 g), mp 141-143 °C (dec).

3296 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

3

H, 4.44; N, 1.40. Conductivity (acetone, 20 °C, Ω^-1cm²mol^-1):

122. H NMR (CD₂Cl₂) δ 1.14 and 1.23 (t, 3H each, J_HH) 6.8

(d, J_CP) 1.2 Hz, CH₃), 19.79 (s, CH₃), 33.51 and 36.79 (s, C₄

1

3

and C₅), 39.55 (ddd, J_CP) 90.8 and 23.4 Hz, J_CP) 8.1 Hz,

Hz, OCH₂CH₃), 2.14 and 2.18 (s, 3H each, CH₃), 2.83 (m, 2H, H₄

and H₆), 2.90 (d, 1H, J_HP) 3.4 Hz, H₂or H₁₀), 3.64 (m, 2H, H₅

PCH₂P), 78.51 and 81.17 (s, C₁and C₈), 100.23 and 109.16 (s, C₃

3

and C₆), 125.72 and 128.20 (s, C₂and C₇), 119.50-137.00 (m,

2

and H₇), 3.79 (m, 5H, OCH₂and H₂or H₁₀), 4.02 and 4.46 (m, 1H

each, PCH₂P), 4.93 (d, 1H, ³J_HP) 8.6 Hz, H₁or H₉), 5.03 (d, 1H,

³J_HP) 10.5 Hz, H₁or H₉), 5.23 (m, 2H, H₃and H₈), 7.10-7.70

(m, 20H, Ph). ¹³C{¹H} NMR (CD₂Cl₂) δ 16.20 (d, ³J_CP) 5.7 Hz,

OCH₂CH₃), 16.22 (d, ³J_CP) 8.9 Hz, OCH₂CH₃), 19.70 and 21.01

(s, CH₃), 32.31 (dd, J_CP) 54.0 and 8.9 Hz, PCH₂P), 37.29 and

37.44 (s, C₄and C₅), 62.41 (d, ²J_CP) 4.4 Hz, C₁or C₈), 63.53 (d,

²J_CP) 6.4 Hz, OCH₂), 64.32 (d, ²J_CP) 7.0 Hz, OCH₂), 72.39 (d,

²J_CP) 5.7 Hz, C₁or C₈), 110.50 and 114.53 (d, ²J_CP) 9.5 Hz, C₃

and C₆), 127.25 (s, C₂and C₇), 128.00-134.50 (m, Ph) ppm. For

7b: yield (method A) 85% (0.484 g), yield (method B) 84% (0.383

g); mp 141-143 °C (dec). Anal. Calcd for RuC₄₇H₄₈F₆O₃P₃ClNSb‚

1/4CH₂Cl₂: C, 48.87; H, 4.21; N, 1.21. Found: C, 48.80; H, 4.07;

Ph), 149.39 (d, J_CP) 9.6 Hz, C_ipsoof OPh), 149.69 (d, J_CP)

10.2 Hz, C_ipsoof OPh) ppm.

Synthesis of [Ru(η⁶-p-cymene)X₂(K¹-P-Ph₂PCH₂P{dNP(dO)-

(OR)₂}Ph₂)] (R ) Et, X ) Br (9a), I (10a), N₃(11a), NCO (12a);

R ) Ph, X ) Br (9b), I (10b), N₃(11b), NCO (12b)). Method

A. A solution containing [Ru(η⁶-p-cymene)Cl(κ²-P,O-Ph₂PCH₂P-

{dNP(dO)(OPh)₂}Ph₂)][SbF₆] (3b), or a mixture of [Ru(η⁶-p-

cymene)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OEt)₂}Ph₂)][SbF₆] (3a)

and [Ru(η⁶-p-cymene)Cl(κ²-P,N-Ph₂PCH₂P{dNP(dO)(OEt)₂}-

Ph₂)][SbF₆] (4a), (0.5 mmol) in 40 mL of methanol was treated, at

room temperature, with the appropriate sodium salt NaX (5 mmol)

for 4 h. The solution was then evaporated to dryness and the solid

residue extracted with dichloromethane and filtered off (Kieselguhr).

The resulting solution was concentrated to ca. 2 mL, and 50 mL of

diethyl ether was then added yielding a yellow-orange microcrys-

talline solid which was washed with diethyl ether (2 × 10 mL)

and vacuum-dried. For 9a: yield 85% (0.395 g). Anal. Calcd for

RuC₃₉H₄₆O₃P₃Br₂N‚1/2CH₂Cl₂: C, 48.75; H, 4.87; N, 1.44.

1

N, 1.28. Conductivity (acetone, 20 °C, Ω^-1cm²mol^-1): 118. H

NMR (CD₂Cl₂) δ 1.88 and 2.07 (s, 3H each, CH₃), 2.64 and 2.74

3

(m, 1H each, H₄and H₆), 3.09 (d, 1H, J_HP) 3.1 Hz, H₂or H₁₀),

3

3.47 (m, 2H, H₅and H₇), 3.65 (d, 1H, J_HP) 4.8 Hz, H₂or H₁₀),

3

4.16 and 4.57 (m, 1H each, PCH₂P), 4.75 (d, 1H, J_HP) 8.8 Hz,

1

H₁or H₉), 4.95 and 5.20 (m, 1H each, H₃and H₈), 5.24 (d, 1H,

³J_HP) 10.8 Hz, H₁or H₉), 6.90-7.60 (m, 30H, Ph). ¹³C{¹H} NMR

(CD₂Cl₂) δ 18.75 and 21.19 (s, CH₃), 33.68 (dd, J_CP) 56.9 and

Found: C, 48.99; H, 4.83; N, 1.39. H NMR (CDCl₃) δ 0.78 (d,

6H, J_HH) 6.9 Hz, CH(CH₃)₂), 0.97 (t, 6H, J_HH) 7.0 Hz,

OCH₂CH₃), 1.86 (s, 3H, CH₃), 2.66 (sept, 1H, J_HH) 6.9 Hz,

CH(CH₃)₂), 3.43 (m, 4H, OCH₂), 4.14 (dd, 2H, ²J_HP) 9.9 and 9.9

Hz, PCH₂P), 5.04 and 5.23 (d, 2H each, J_HH) 6.0 Hz, CH of

p-cymene), 7.19-8.07 (m, 20H, Ph). ¹³C{¹H} NMR (CDCl₃) δ

16.07 (d, ³J_CP) 8.2 Hz, OCH₂CH₃), 17.55 (s, CH₃), 21.23 (s, CH-

10.8 Hz, PCH₂P), 37.13 and 37.54 (s, C₄and C₅), 61.76 (d, ²J_CP

)

2

5.0 Hz, C₁or C₈), 73.25 (d, J_CP) 6.4 Hz, C₁or C₈), 111.26 and

2

113.86 (d, J_CP) 9.5 Hz, C₃and C₆), 119.93-132.73 (m, Ph),

2

127.61 (s, C₂and C₇), 151.81 (d, J_CP) 7.6 Hz, C_ipsoof OPh),

2

3

152.00 (d, J_CP) 8.4 Hz, C_ipsoof OPh) ppm.

(CH₃)₂), 23.32 (ddd, J_CP) 69.5 and 18.8 Hz, J_CP) 9.5 Hz,

Synthesis of [Ru(η³:η³-C₁₀H₁₆)(K³-P,N,O-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)][SbF₆]₂(R ) Et (8a), Ph (8b)). Complexes 8a,b,

isolated as yellow solids, were prepared as described for 5a,b

starting either from neutral complexes [Ru(η³:η³-C₁₀H₁₆)Cl₂(κ¹-P-

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] (6a,b) (0.5 mmol) (method A)

or cationic derivatives [Ru(η³:η³-C₁₀H₁₆)Cl(κ²-P,O-Ph₂PCH₂P{d

NP(dO)(OR)₂}Ph₂)][SbF₆] (7a,b) (0.5 mmol) (method B). For 8a:

yield (method A) 83% (0.516 g), yield (method B) 85% (0.529 g);

mp 136-138 °C (dec). Anal. Calcd for RuC₃₉H₄₈F₁₂O₃P₃Sb₂N: C,

37.65; H, 3.89; N, 1.12. Found: C, 37.47; H, 3.96; N, 1.22.

PCH₂P), 30.40 (s, CH(CH₃)₂), 60.63 (d, J_CP) 6.0 Hz, OCH₂),

2

85.43 (d, J_CP) 6.3 Hz, CH of p-cymene), 90.47 (d, J_CP) 4.1

Hz, CH of p-cymene), 94.18 and 109.49 (s, C of p-cymene),

127.55-134.12 (m, Ph) ppm. For 9b: yield 83% (0.426 g). Anal.

Calcd for RuC₄₇H₄₆O₃P₃Br₂N‚1/4CH₂Cl₂: C, 54.16; H, 4.47; N,

1.34. Found: C, 54.14; H, 4.34; N, 1.40. ¹H NMR (CDCl₃) δ 0.73

(d, 6H, J_HH) 6.8 Hz, CH(CH₃)₂), 1.87 (s, 3H, CH₃), 2.61 (sept,

2

1H, J_HH) 6.8 Hz, CH(CH₃)₂), 4.19 (dd, 2H, J_HP) 9.8 and 9.8

Hz, PCH₂P), 5.03 and 5.23 (d, 2H each, J_HH) 6.1 Hz, CH of

p-cymene), 6.79-7.91 (m, 30H, Ph). ¹³C{¹H} NMR (CDCl₃) δ

17.98 (s, CH₃), 21.43 (s, CH(CH₃)₂), 23.99 (ddd, J_CP) 74.3 and

1

Conductivity (acetone, 20 °C, Ω^-1cm²mol^-1): 193. H NMR

4

3

(CD₂Cl₂) δ 1.09 and 1.35 (td, 3H each, J_HH) 7.0 Hz, J_HP) 1.1

20.1 Hz, J_CP) 6.4 Hz, PCH₂P), 30.97 (s, CH(CH₃)₂), 86.11 (d,

2

Hz, OCH₂CH₃), 1.74 and 2.46 (s, 3H each, CH₃), 2.83 (m, 1H, H₄

²J_CP) 5.8 Hz, CH of p-cymene), 91.07 (d, J_CP) 4.7 Hz, CH of

or H₆), 2.96 (m, 2H, H₄, H₅, H₆or H₇), 3.22 (m, 1H, H₅or H₇),

p-cymene), 94.67 and 109.64 (s, C of p-cymene), 120.60-135.84

(m, Ph), 152.66 (d, J_CP) 7.6 Hz, C_ipsoof OPh) ppm. For 10a:

3

2

3.55 (s, 1H, H₁or H₉), 3.92 (m, 4H, OCH₂), 3.96 (d, 1H, J_HP

)

2.8 Hz, H₂or H₁₀), 4.12 and 4.40 (m, 1H each, PCH₂P), 4.51 and

4.80 (m, 1H each, H₃and H₈), 4.56 (s, 1H, H₁or H₉), 5.19 (d, 1H,

³J_HP) 1.8 Hz, H₂or H₁₀), 7.15-8.15 (m, 20H, Ph). ¹³C{¹H} NMR

yield 82% (0.420 g). Anal. Calcd for RuC₃₉H₄₆O₃P₃I₂N‚CH₂Cl₂:

C, 43.30; H, 4.36; N, 1.26. Found: C, 43.63; H, 4.11; N, 1.28. ¹H

NMR (CDCl₃) δ 0.64 (d, 6H, J_HH) 6.8 Hz, CH(CH₃)₂), 0.88 (t,

6H, J_HH) 7.0 Hz, OCH₂CH₃), 1.94 (s, 3H, CH₃), 2.91 (sept, 1H,

J_HH) 6.8 Hz, CH(CH₃)₂), 3.32 (m, 4H, OCH₂), 4.33 (dd, 2H, ²J_HP

) 9.6 and 9.6 Hz, PCH₂P), 4.89 and 5.15 (d, 2H each, J_HH) 6.0

Hz, CH of p-cymene), 7.08-7.96 (m, 20H, Ph). ¹³C{¹H} NMR

3

(CD₂Cl₂) δ 15.28 and 15.51 (d, J_CP) 7.4 Hz, OCH₂CH₃), 17.61

and 18.70 (s, CH₃), 32.32 and 36.13 (s, C₄and C₅), 39.72 (ddd,

J_CP) 81.0 and 23.6 Hz, ³J_CP) 7.7 Hz, PCH₂P), 66.76 (d, ²J_CP

)

2

7.9 Hz, OCH₂), 67.11 (d, J_CP) 7.4 Hz, OCH₂), 77.25 and 80.48

(s, C₁and C₈), 98.63 and 108.13 (s, C₃and C₆), 123.99 and 125.61

(s, C₂and C₇), 121.30-135.65 (m, Ph) ppm. For 8b: yield (method

A) 84% (0.563 g), yield (method B) 80% (0.535 g); mp 153-155

°C (dec). Anal. Calcd for RuC₄₇H₄₈F₁₂O₃P₃Sb₂N: C, 42.12; H, 3.61;

N, 1.04. Found: C, 42.30; H, 3.55; N, 1.10. Conductivity (acetone,

20 °C, Ω^-1cm²mol^-1): 177. ¹H NMR (CD₂Cl₂) δ 1.73 and 2.25

(s, 3H each, CH₃), 2.92 (m, 3H, H₄, H₅, H₆or H₇), 3.22 (m, 1H,

3

(CDCl₃) δ 16.14 (d, J_CP) 7.8 Hz, OCH₂CH₃), 18.66 (s, CH₃),

3

21.63 (s, CH(CH₃)₂), 30.08 (ddd, J_CP) 76.3 and 23.0 Hz, J_CP

)

2

7.7 Hz, PCH₂P), 31.74 (s, CH(CH₃)₂), 60.74 (d, J_CP) 6.0 Hz,

OCH₂), 85.79 (d, ²J_CP) 6.0 Hz, CH of p-cymene), 90.89 (d, ²J_CP

) 4.2 Hz, CH of p-cymene), 95.68 and 111.91 (s, C of p-cymene),

127.51-134.39 (m, Ph) ppm. For 10b: yield 83% (0.465 g). Anal.

Calcd for RuC₄₇H₄₆O₃P₃I₂N: C, 50.37; H, 4.14; N, 1.25. Found:

3

1

H₅or H₇), 3.67 (s, 1H, H₁or H₉), 3.74 (d, 1H, J_HP) 1.9 Hz, H₂

C, 49.98; H, 3.72; N, 1.22. H NMR (CDCl₃) δ 0.73 (d, 6H, J_HH

or H₁₀), 4.20 and 4.60 (m, 1H each, PCH₂P), 4.50 (s, 1H, H₁or

H₉), 4.71 and 4.91 (m, 1H each, H₃and H₈), 5.25 (s, 1H, H₂or

H₁₀), 6.50-8.30 (m, 30H, Ph). ¹³C{¹H} NMR (CD₂Cl₂) δ 18.27

) 6.8 Hz, CH(CH₃)₂), 1.59 (s, 3H, CH₃), 3.04 (sept, 1H, J_HH)

6.8 Hz, CH(CH₃)₂), 4.51 (dd, 2H, ²J_HP) 8.8 and 8.8 Hz, PCH₂P),

5.00 and 5.25 (d, 2H each, J_HH) 5.5 Hz, CH of p-cymene), 6.80-

Inorganic Chemistry, Vol. 42, No. 10, 2003 3297

Cadierno et al.

Table 1. Crystallographic Data for Complexes 2b, 3b, 7a, and 12b

2b

3b

7a

12b

.

chemical formula

fw

T (°C)

wavelength (Å)

space group

a, Å

C₄₇H₄₆O₃P₃Cl₂NRu

937.73

C₄₇H₄₆F₆P₄O₃ClNRu

1047.25

20(2)

0.71073

P2₁/c (No. 14)

10.2905(9)

21.584(2)

22.0612(2)

90

95.640(2)

90

4

4876.3(7)

1.426

5.70

C₃₉H₄₈F₄O₃P₃BClNRu

895.02

20(2)

0.71073

P2₁/n (No. 14)

13.959(5)

15.042(6)

19.966(8)

90

100.253(9)

90

4

4125(3)

1.441

6.16

C₄₉H₄₆O₅N₃P₃CH₂Cl₂

1035.79

-73(2)

1.54184

Pca2₁(No. 29)

23.3059(3)

9.1822(1)

22.6599(4)

90

-153(2)

1.54184

P1h (No. 2)

10.518(1)

13.869(2)

15.856(2)

80.267(6)

85.289(6)

70.543(6)

2

b, Å

c, Å

R, deg

â, deg

γ, deg

Z

90

4

4849.2(1)

1.419

4.965

V, Å³

2148.7(4)

1.449

5.488

F

_calcd, g cm^-3

µ, cm^-1

weight function (a, b)

R1^a[I > 2σ(I)]

wR2^a[I > 2σ(I)]

R1 (all data)

(0.0492, 0)

0.0480

0.0978

(0.0963, 0)

0.0688

0.1517

(0.0573, 0)

0.0586

0.1156

(0.0755, 2.5453)

0.0385

0.1070

0.0933

0.2272

0.1684

0.0424

wR2 (all data)

0.1241

0.2073

0.1464

0.1354

^aR1 ) ∑(|F_o| - |F_c|)/∑|F_o|; wR2 ) {∑[w(F_o- F_c)]/∑[w(F_o)]}^1/2

.

2

8.00 (m, 30H, Ph). ¹³C{¹H} NMR (CDCl₃) δ 19.05 (s, CH₃), 21.77

(m, Ph and NCO) ppm. For 12b: yield 75% (0.356 g). Anal. Calcd

3

(s, CH(CH₃)₂), 30.36 (ddd, J_CP) 72.3 and 22.3 Hz, J_CP) 5.9

for RuC₄₉H₄₆O₅N₃P₃: C, 61.89; H, 4.87; N, 4.42. Found: C, 61.68;

Hz, PCH₂P), 32.23 (s, CH(CH₃)₂), 86.46 (d, ²J_CP) 5.7 Hz, CH of

H, 4.82; N, 4.03. IR (KBr, cm^-1) ν 2225 (NdCdO). H NMR

1

2

p-cymene), 91.35 (d, J_CP) 4.5 Hz, CH of p-cymene), 96.26 and

(CDCl₃) δ 0.83 (d, 6H, J_HH) 6.7 Hz, CH(CH₃)₂), 1.74 (s, 3H,

CH₃), 2.18 (sept, 1H, J_HH) 6.7 Hz, CH(CH₃)₂), 3.59 (dd, 2H, ²J_HP

) 9.6 and 9.6 Hz, PCH₂P), 5.06 and 5.14 (br, 2H each, CH of

p-cymene), 6.77-7.79 (m, 30H, Ph). ¹³C{¹H} NMR (CDCl₃) δ

17.62 (s, CH₃), 21.43 (s, CH(CH₃)₂), 21.68 (ddd, J_CP) 71.2 and

112.06 (s, C of p-cymene), 120.80-133.81 (m, Ph), 152.63 (d, ²J_CP

) 7.6 Hz, C_ipsoof OPh) ppm. For 11a: yield: 79% (0.338 g). Anal.

Calcd for RuC₃₉H₄₆N₇O₃P₃: C, 54.80; H, 5.42; N, 11.47. Found:

C, 54.81; H, 5.10; N, 11.99. IR (KBr, cm^-1) ν 2036 (NdNdN).

¹H NMR (CD₂Cl₂) δ 0.92 (d, 6H, J_HH) 6.6 Hz, CH(CH₃)₂), 1.00

(t, 6H, J_HH) 6.9 Hz, OCH₂CH₃), 1.75 (s, 3H, CH₃), 2.33 (sept,

1H, J_HH) 6.6 Hz, CH(CH₃)₂), 3.41 (m, 4H, OCH₂), 4.03 (dd, 2H,

3

17.5 Hz, J_CP) 7.2 Hz, PCH₂P), 30.39 (s, CH(CH₃)₂), 86.56 (d,

2

²J_CP) 5.6 Hz, CH of p-cymene), 90.10 (d, J_CP) 4.5 Hz, CH of

p-cymene), 95.79 and 108.04 (s, C of p-cymene), 120.31-133.53

²J_HP) 9.7 and 9.7 Hz, PCH₂P), 5.09 and 5.14 (d, 2H each, J_HH

)

(m, Ph and NCO), 152.00 (d, J_CP) 6.8 Hz, C_ipsoof OPh) ppm.

2

5.1 Hz, CH of p-cymene), 7.07-7.85 (m, 20H, Ph). ¹³C{¹H} NMR

Method B. A solution of the corresponding complex [Ru(η⁶-p-

cymene)(κ³-P,N,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂(5a,b)

(0.2 mmol) in 20 mL of methanol was treated, at room temperature,

with the appropriate sodium salt NaX (2 mmol) for 2 h. The solution

was then evaporated to dryness and the solid residue extracted with

dichloromethane and filtered off (Kieselguhr). The resulting solution

was concentrated to ca. 2 mL, and 30 mL of diethyl ether was

added yielding a yellow-orange microcrystalline solid which was

washed with diethyl ether (2 × 5 mL) and vacuum-dried. For 9a:

yield 80% (0.149 g). For 9b: yield 87% (0.178 g). For 10a: yield

84% (0.172 g). For 10b: yield 80% (0.179 g). For 11a: yield 82%

(0.140 g). For 11b: yield 72% (0.137 g). For 12a: yield 79% (0.135

g). For 12b: yield 77% (0.146 g).

3

(CD₂Cl₂) δ 16.12 (d, J_CP) 8.0 Hz, OCH₂CH₃), 16.63 (s, CH₃),

20.72 (ddd, J_CP) 77.4 and 14.5 Hz, ³J_CP) 7.6 Hz, PCH₂P), 21.62

2

(s, CH(CH₃)₂), 30.19 (s, CH(CH₃)₂), 60.95 (d, J_CP) 6.5 Hz,

2

OCH₂), 86.26 (d, J_CP) 5.1 Hz, CH of p-cymene), 89.63 (s, CH

of p-cymene), 95.86 and 109.05 (s, C of p-cymene), 125.50-135.44

(m, Ph) ppm. For 11b: yield 78% (0.371 g). Anal. Calcd for

RuC₄₇H₄₆N₇O₃P₃: C, 59.36; H, 4.87; N, 10.31. Found: C, 59.47;

1

H, 4.37; N, 10.20. IR (KBr, cm^-1) ν 2035 (NdNdN). H NMR

(CDCl₃) δ 0.89 (d, 6H, J_HH) 6.8 Hz, CH(CH₃)₂), 1.78 (s, 3H,

CH₃), 2.35 (sept, 1H, J_HH) 6.8 Hz, CH(CH₃)₂), 3.48 (dd, 2H, ²J_HP

) 9.8 and 9.8 Hz, PCH₂P), 5.08 and 5.15 (d, 2H each, J_HH) 5.8

Hz, CH of p-cymene), 6.76-7.75 (m, 30H, Ph). ¹³C{¹H} NMR

(CDCl₃) δ 16.94 (s, CH₃), 20.35 (ddd, J_CP) 73.4 and 14.0 Hz,

³J_CP) 6.6 Hz, PCH₂P), 21.81 (s, CH(CH₃)₂), 30.43 (s, CH(CH₃)₂),

General Procedure for Catalytic Transfer Hydrogenation of

Cyclohexanone. Under inert atmosphere, cyclohexanone (0.49 g,

5 mmol), the ruthenium catalyst precursor (0.02 mmol, 0.4 mol

%), and 20 mL of propan-2-ol are introduced into a Schlenk tube

fitted with a condenser and heated at 82 °C for 15 min. Then NaOH

is added (5 mL of a 0.096 M solution in propan-2-ol, 9.6 mol %),

and the reaction is monitored by gas chromatography. Cyclohexanol

and acetone are the only products detected in all cases.

X-ray Crystal Structure Determination of Complexes 2b, 3b,

7a, and 12b. Crystals suitable for X-ray diffraction analysis were

obtained, in all the cases, by slow diffusion of pentane in a saturated

solution of the complex in dichloromethane.¹²The most relevant

crystal and refinement data are collected in Table 1. Diffraction

data for 3b and 7a were recorded on a Bruker Smart CCD

diffractometer using Mo KR radiation with a nominal crystal-

detector distance of 40 mm, using 1371 frames at 0.3° intervals

with 15 s exposure time per frame and 1271 frames at 0.3° intervals

2

86.53 (d, J_CP) 5.3 Hz, CH of p-cymene), 90.02 (d, J_CP) 3.5

Hz, CH of p-cymene), 95.75 and 109.18 (s, C of p-cymene),

2

120.61-133.96 (m, Ph), 152.61 (d, J_CP) 7.6 Hz, C_ipsoof OPh)

ppm. For 12a: yield 77% (0.329 g). Anal. Calcd for RuC₄₁H₄₆O₅-

N₃P₃‚CH₂Cl₂: C, 53.67; H, 5.14; N, 4.47. Found: C, 53.26; H,

4.77; N, 4.57. IR (KBr, cm^-1) ν 2227 (NdCdO). ¹H NMR (CDCl₃)

δ 0.93 (m, 12H, CH(CH₃)₂and OCH₂CH₃), 1.77 (s, 3H, CH₃), 2.19

(sept, 1H, J_HH) 5.6 Hz, CH(CH₃)₂), 3.46 (m, 4H, OCH₂), 3.58

(dd, 2H, ²J_HP) 10.0 and 10.0 Hz, PCH₂P), 5.12 and 5.16 (br, 2H

each, CH of p-cymene), 7.26-7.94 (m, 20H, Ph). ¹³C{¹H} NMR

3

(CDCl₃) δ 16.10 (d, J_CP) 8.2 Hz, OCH₂CH₃), 17.54 (s, CH₃),

3

21.50 (s, CH(CH₃)₂), 22.52 (ddd, J_CP) 75.7 and 19.5 Hz, J_CP

)

2

10.8 Hz, PCH₂P), 30.37 (s, CH(CH₃)₂), 60.78 (d, J_CP) 5.8 Hz,

OCH₂), 86.47 (d, J_CP) 4.7 Hz, CH of p-cymene), 89.97 (s, CH

2

of p-cymene), 96.00 and 108.52 (s, C of p-cymene), 127.82-133.54

3298 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

Table 2. ³¹P{¹H} NMR Data for the Iminophosphorane-Phosphine Ligands and Their Metal Complexes^a

compd

Ph₂P

Ph₂PdN

(RO)₂PdO

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂

R ) Et (1a)^b

-27.39 (d, ²J_PP) 61.0)

-27.65 (d, ²J_PP) 63.1)

15.29 (dd, ²J_PP) 61.0, 28.5)

4.59 (d, ²J_PP) 28.5)

-6.04 (d, ²J_PP) 31.3)

R ) Ph (1b)^b

16.87 (dd, ²J_PP) 63.1, 31.3)

[Ru(η⁶-p-cymene)X₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)]

R ) Et; X ) Cl (2a)^b

R ) Et; X ) Br (9a)^b

R ) Et; X ) I (10a)^b

R ) Et; X ) N₃(11a)^c

R ) Et; X ) NCO (12a)^b

R ) Ph; X ) Cl (2b)^b

R ) Ph; X ) Br (9b)^b

R ) Ph; X ) I (10b)^b

R ) Ph; X ) N₃(11b)^b

R ) Ph; X ) NCO (12b)^b

22.97 (d, ²J_PP) 38.5)

11.00 (dd, ²J_PP) 38.5, 30.0)

8.82 (dd, ²J_PP) 36.6, 31.7)

13.08 (dd, ²J_PP) 35.6, 31.1)

9.00 (dd, ²J_PP) 37.9, 32.5)

9.69 (dd, ²J_PP) 39.1, 31.7)

13.06 (dd, ²J_PP) 38.9, 31.3)

13.77 (dd, ²J_PP) 37.8, 31.7)

15.17 (dd, ²J_PP) 36.6, 32.6)

12.64 (dd, ²J_PP) 38.9, 32.5)

12.30 (dd, ²J_PP) 36.6, 32.5)

1.83 (d, ²J_PP) 30.0)

1.05 (d, ²J_PP) 31.7)

1.52 (d, ²J_PP) 31.1)

1.57 (d, ²J_PP) 32.5)

1.40 (d, ²J_PP) 31.7)

-8.57 (d, ²J_PP) 31.3)

-8.57 (d, ²J_PP) 31.7)

-8.90 (d, ²J_PP) 32.6)

-8.44 (d, ²J_PP) 32.5)

-9.12 (d, ²J_PP) 32.5)

16.00 (d, ²J_PP) 36.6)

16.20 (d, ²J_PP) 35.6)

27.62 (d, ²J_PP) 37.9)

26.62 (d, ²J_PP) 39.1)

23.29 (d, ²J_PP) 38.9)

19.29 (d, ²J_PP) 37.8)

16.74 (d, ²J_PP) 36.6)

28.00 (d, ²J_PP) 38.9)

26.95 (d, ²J_PP) 36.6)

[Ru(η³:η³-C₁₀H₁₆)Cl₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)]

R ) Et (6a)^b

R ) Ph (6b)^b

19.81 (d, ²J_PP) 36.6)

9.91 (dd, ²J_PP) 36.6, 31.7)

1.64 (d, ²J_PP) 31.7)

-8.89 (d, ²J_PP) 34.0)

20.23 (d, ²J_PP) 36.6)

12.02 (dd, ²J_PP) 36.6, 34.0)

[Ru(η⁶-p-cymene)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]

R ) Et (3a)^c

R ) Ph (3b)^c

22.97 (s)

23.94 (s)

11.82 (d, ²J_PP) 38.5)

8.21 (d, ²J_PP) 38.5)

-0.79 (d, ²J_PP) 48.1)

9.20 (d, ²J_PP) 48.1)

[Ru(η³:η³-C₁₀H₁₆)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]

R ) Et (7a)^c

R ) Ph (7b)^c

22.22 (s)

24.86 (s)

10.56 (d, ²J_PP) 37.0)

9.49 (d, ²J_PP) 37.0)

-1.88 (d, ²J_PP) 49.5)

10.37 (d, ²J_PP) 49.5)

[Ru(η⁶-p-cymene)Cl(κ²-P,N-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]

R ) Et (4a)^c

47.22 (dd, ²J_PP) 20.2, ³J_PP) 6.1) 58.68 (dd, ²J_PP) 20.2, 6.1)

10.24 (dd, ²J_PP) 6.1, ³J_PP) 6.1)

[Ru(η⁶-p-cymene)(κ³-P,N,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂

R ) Et (5a)^c

R ) Ph (5b)^c

41.90 (d, ²J_PP) 36.3)

54.45 (dd, ²J_PP) 36.3, 3.8)

18.28 (d, ²J_PP) 3.8)

6.33 (s)

41.68 (d, ²J_PP) 35.7)

55.62 (d, ²J_PP) 35.7)

[Ru(η³:η³-C₁₀H₁₆)(κ³-P,N,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂

R ) Et (8a)^c

R ) Ph (8b)^c

46.64 (d, ²J_PP) 11.5)

45.76 (d, ²J_PP) 9.0)

50.88 (dd, ²J_PP) 11.5, 6.5)

51.09 (dd, ²J_PP) 9.0, 8.1)

4.45 (d, ²J_PP) 6.5)

-6.47 (d, ²J_PP) 8.1)

^aδ in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; dd, doublet of doublets. ^bSpectra recorded in CDCl₃. ^cSpectra recorded in CD₂Cl₂.

with 20 s exposure time per frame, respectively. The diffraction

frames were integrated using the SAINT package¹³and corrected

for absorption with SADABS.¹⁴Sets for compounds 2b and 12b

were collected on a Nonius Kappa CCD single crystal diffractometer

using Cu KR radiation with a crystal-detector distance fixed at

29 mm; a total of 1238 (20 s exposure time per frame) and 1125

frames (60 s exposure time per frame), respectively, were recorded

using the oscillation method (with 2° oscillation). Data collection

strategy was calculated with the program Collect.¹⁵Data reduction

and cell refinement were performed with the programs HKL Denzo

and Scalepack.¹⁶Absorption correction was applied by means of

XABS2.¹⁷

of the refinements, all positional parameters and the anisotropic

temperature factors of all the non-H atoms were refined (the F atoms

of the disordered PF₆^-anion in 3b were isotropically refined). The

H atoms for all the structures were geometrically located and refined

riding on their parent atoms with common isotropic thermal

2

parameters. The function minimized was [∑w(F_o²- F_c²)/∑w(F_o)]^1/2

2

where w ) 1/[σ²(F_o) + (aP)²+ bP] (a and b values are shown in

2

Table 1) with σ(F_o) from counting statistics and P ) (max(F_o, 0)

+ 2F_c²)/3. Atomic scattering factors were taken from the Interna-

tional Tables for X-ray Crystallography.²⁰Geometrical calculations

were made with PARST.²¹The crystallographic plots were made

with PLATON.²²

Computational Details. All calculations were carried out with

the Gaussian98 program package.²³The molecular geometries were

optimized, without any molecular symmetry constraint, using

Schlegel’s analytical gradient procedure²⁴at the B3-LYP variant

of density functional theory²⁵with the standard split-valence 6-31G-

(d) basis set for C, N, O, and H,²⁶and the pseudorelativistic effective

core potential (ECP) by Hay and Wadt for Ru, P, and Cl.²⁷This

basis set was referred to as DZV(d). The optimized structures were

characterized as minima (representing equilibrium structures) by

analytic frequency calculations which also yielded zero-point

vibrational energy and thermochemical analysis. Single-point

All the structures were solved by Patterson interpretation and

phase expansion using DIRDIF.¹⁸Isotropic least-squares refinement

on F²using SHELXL97 was performed.¹⁹During the final stages

(12) Only the hexafluorophosphate salt of 3b (Anal. Calcd for RuC₄₇H₄₆F₆-

P₄O₃ClN: C, 53.90; H, 4.43; N, 1.34. Found: C, 53.72; H, 4.51; N,

1.27.) and the tetrafluoroborate salt of 7a (Anal. Calcd for RuC₃₉H₄₈-

F₄O₃P₃BClN: C, 52.33; H, 5.40; N, 1.56. Found: C, 52.21; H, 5.31;

N, 1.68.) gave crystals suitable for X-ray diffraction. These compounds

were obtained using AgPF₆and AgBF₄, respectively, instead of

AgSbF₆.

(13) SAINT, version 6.02; Bruker Analytical X-ray Systems; Madison, WI,

2000.

(14) Sheldrick, G. M. SADABS: Empirical Absorption Program; University

of Go¨ttingen: Go¨ttingen, Germany, 1996.

(19) Sheldrick, G. M. SHELXL97: Program for the Refinement of Crystal

Structures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.

(20) International Tables for X-ray Crystallography; Kynoch Press: Bir-

mingham, U.K., 1974; Vol. IV. (Present distributor: Kluwer Academic

Publishers: Dordrecht, The Netherlands.)

(21) Nardelli, M. Comput. Chem. 1983, 7, 95.

(22) Spek A. L. PLATON: A Multipurpose Crystallographic Tool;

University of Utrecht: Utrecht, The Netherlands, 2000.

(15) Collect; Nonius BV: Delft, The Netherlands, 1997-2000.

(16) Otwinowski, Z.; Minor, W. Methods Enzymol. 1997, 276, 307.

(17) Parkin, S.; Moezzi, B.; Hope, H. J. Appl. Crystallogr. 1995, 28, 53.

(18) Beurskens, P. T.; Beurskens, G.; Bosman, W. P.; de Gelder, R.; Garc´ıa-

Granda, S.; Gould, R. O.; Israe¨l, R.; Smits, J. M. M. The DIRDIF-96

Program System; Crystallographic Laboratory; University of Nij-

megen: Nijmegen, The Netherlands, 1996.

Inorganic Chemistry, Vol. 42, No. 10, 2003 3299

Cadierno et al.

2

Scheme 1

-27.39 (d, J_PP) 61.0 Hz, Ph₂P), 4.59 (d, J_PP) 28.5 Hz,

2

(EtO)₂PdO), and 15.29 (dd, J_PP) 61.0 and 28.5 Hz, Ph₂-

2

PdN); 1b, δ -27.65 (d, J_PP) 63.1 Hz, Ph₂P), -6.04 (d,

²J_PP) 31.3 Hz, (PhO)₂PdO), and 16.87 (dd, J_PP) 63.1

2

and 31.3 Hz, Ph₂PdN)). (ii) Regarding ¹H NMR, there is a

doublet resonance (ca. 3.4 ppm) for the methylenic hydrogens

due to the coupling with the phosphorus atom of the Ph₂-

2

PdN unit (ca. J_HP) 14 Hz; coupling with the Ph₂P

calculations on the DFT geometries were performed with the

incorporation of correlation energy using Møller-Plesset perturba-

tion theory with second-order corrections (MP2).²⁸

2

phosphorus atom, usually in the range J_HP) 1-3 Hz for

related Ph₂PCH₂P(dNR)Ph₂ligands,³has been not observed).

And, (iii) regarding ¹³C{¹H} NMR, there is a doublet of

doublets signal (ca. J_CP) 65 (coupling with Ph₂PdN) and

34 Hz (coupling with Ph₂P)) for the PCH₂P carbon which

appears at ca. 30 ppm.

Results and Discussion

Synthesis and Characterization of Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂(R ) Et (1a), Ph (1b)). Monoimination of

bis(diphenylphosphino)methane (dppm) with azides has been

successfully applied to the preparation of several iminophos-

phorane-phosphine ligands Ph₂PCH₂P(dNR)Ph₂.³The high

selectivity of these reactions seems to be sterically controlled

since the proximity of the two diphenylphosphino groups

hinders the imination at the second phosphorus atom.²⁹As

expected, we have found that dppm reacts with an equimolar

amount of the phosphoryl azides (RO)₂P(dO)N₃(R ) Et,

Ph), in THF at -78°C, to afford the new (N-phosphoryl-

iminophosphoranyl)(phosphino)methane derivatives Ph₂-

PCH₂P{)NP(dO)(OR)₂}Ph₂(R ) Et (1a), Ph (1b)) in good

yields (93% and 86%, respectively) (Scheme 1).

Compounds 1a,b have been isolated as air-stable white

solids. They are soluble in chlorinated solvents, THF,

acetonitrile, and diethyl ether, and are insoluble in apolar

solvents such as pentane or hexane. Their NMR spectro-

scopic data (¹H, ³¹P{¹H}, and ¹³C{¹H}) and elemental

analyses are in agreement with the proposed structures (see

the Experimental Section and Table 2),³⁰the former corre-

sponding well with those reported in the literature for related

compounds.³Relevant spectroscopic features are the follow-

ing: (i) Regarding ³¹P{¹H} NMR, three well separated

signals with equal relative intensities are present (1a, δ

Coordination of Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂(R )

Et (1a), Ph (1b)) to Ruthenium(II) and Ruthenium(IV)

Fragments. The ability of the novel iminophosphorane-

phosphines Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂(1a,b) to act as

mono-, bi-, or tridentate ligands has been explored. The

readily available ruthenium(II) and ruthenium(IV) chloro-

bridged dimers [{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂]⁹and [{Ru-

(η³:η³-C₁₀H₁₆)(µ-Cl)Cl}₂],¹⁰respectively, were chosen as

starting materials due to their versatile reactivity toward

polyfunctional ligands.^31,32Results are summarized in Schemes

2 and 3.

(a) K¹-P-Complexes [Ru(η⁶-p-cymene)Cl₂(K¹-P-Ph₂PCH₂-

P{dNP(dO)(OR)₂}Ph₂)] (R ) Et (2a), Ph (2b)) and [Ru-

(η³:η³-C₁₀H₁₆)Cl₂(K¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}-

Ph₂)] (R ) Et (6a), Ph (6b)). As expected from our previous

results,⁵the treatment of dimers [{Ru(η⁶-p-cymene)(µ-Cl)-

Cl}₂] and [{Ru(η³:η³-C₁₀H₁₆)(µ-Cl)Cl}₂] with a 2-fold excess

of 1a,b, in dichloromethane at room temperature, results in

the cleavage of the chloride bridges and the clean formation

of monomeric compounds [Ru(η⁶-p-cymene)Cl₂(κ¹-P-Ph₂-

PCH₂P{dNP(dO)(OR)₂}Ph₂)] (R ) Et (2a), Ph (2b);

Scheme 2) and [Ru(η³:η³-C₁₀H₁₆)Cl₂(κ¹-P-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)] (R ) Et (6a), Ph (6b); Scheme 3),

respectively (73-97% yield).

(23) Frisch, M. J.; Trucks, G. W.; Schlegel, H. B.; Scuseria, G. E.; Robb,

M. A.; Cheeseman, J. R.; Zakrzewski, V. G.; Montgomery, J. A., Jr.;

Stratmann, R. E.; Burant, J. C.; Dapprich, S.; Millam, J. M.; Daniels,

A. D.; Kudin, K. N.; Strain, M. C.; Farkas, O.; Tomasi, J.; Barone,

V.; Cossi, M.; Cammi, R.; Mennucci, B.; Pomelli, C.; Adamo, C.;

Clifford, S.; Ochterski, J.; Petersson, G. A.; Ayala, P. Y.; Cui, Q.;

Morokuma, K.; Malick, D. K.; Rabuck, A. D.; Raghavachari, K.;

Foresman, J. B.; Cioslowski, J.; Ortiz, J. V.; Stefanov, B. B.; Liu, G.;

Liashenko, A.; Piskorz, P.; Komaromi, I.; Gomperts, R.; Martin, R.

L.; Fox, D. J.; Keith, T.; Al-Laham, M. A.; Peng, C. Y.; Nanayakkara,

A.; Gonzalez, C.; Challacombe, M.; Gill, P. M. W.; Johnson, B. G.;

Chen, W.; Wong, M. W.; Andres, J. L.; Head-Gordon, M.; Replogle,

E. S.; Pople, J. A. Gaussian 98, revision A.7; Gaussian, Inc.:

Pittsburgh, PA, 1998.

The characterization of complexes 2a,b and 6a,b was

achieved by means of standard spectroscopic techniques (¹H,

³¹P{¹H}, and ¹³C{¹H} NMR) as well as elemental analyses

(31) For reviews on the chemistry of dimers [{Ru(η⁶-arene)(µ-Cl)Cl}₂]

see: (a) Le Bozec, H.; Touchard, D.; Dixneuf, P. H. AdV. Organomet.

Chem. 1989, 29, 163. (b) Bennett, M. A. In ComprehensiVe Orga-

nometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson, G.,

Eds.; Pergamon Press: Oxford, 1995; Vol. 7, p 549. (c) Bennett, M.

A. Coord. Chem. ReV. 1997, 166, 225. (d) Pigge, F. C.; Coniglio, J.

J. Curr. Org. Chem. 2001, 5, 757.

(32) For recent references on the chemistry of the bis(allyl)-ruthenium-

(IV) dimer [{Ru(η³:η³-C₁₀H₁₆)(µ-Cl)Cl}₂] see: (a) Herrmann, W. A.;

Schattenmann, W. C.; Nuyken, O.; Glander, S. C. Angew. Chem., Int.

Ed. Engl. 1996, 35, 1087. (b) Slawin, A. M. Z.; Smith, M. B.;

Woollins, J. D. J. Chem. Soc., Dalton Trans. 1996, 4575. (c) Aucott,

S. M.; Slawin, A. M. Z.; Woollins, J. D. J. Organomet. Chem. 1999,

582, 82. (d) Werner, H.; Fries, G.; Weberndo¨rfer, B. J. Organomet.

Chem. 2000, 607, 182. (e) Sahay, A. N.; Pandey, D. S.; Walawalkar,

M. G. J. Organomet. Chem. 2000, 613, 250. (f) Cadierno, V.; Garc´ıa-

Garrido, S. E.; Gimeno, J. J. Organomet. Chem. 2001, 637-639, 767.

(g) Werner, H.; Stu¨er, W.; Jung, S.; Weberndo¨rfer, B.; Wolf, J. Eur.

J. Inorg. Chem. 2002, 1076. (h) Zhang, Q.; Aucott, S. M.; Slawin, A.

M. Z.; Woollins, J. D. Eur. J. Inorg. Chem. 2002, 1635. (i) Cadierno,

V.; Garc´ıa-Garrido, S. E.; Gimeno, J. Inorg. Chim. Acta 2003, 347,

41.

(24) Schlegel, H. B. J. Comput. Chem. 1982, 3, 214.

(25) Becke, A. D. J. Chem. Phys. 1993, 98, 5648.

(26) (a) Hariharan, P. C.; Pople, J. A. Theor. Chim. Acta 1973, 28, 213.

(b) Hehre, W. J.; Ditchfield, R.; Pople, J. A. J. Chem. Phys. 1972, 56,

2257.

(27) Wadt, W. R.; Hay, P. J. J. Chem. Phys. 1985, 82, 284.

(28) Møller, C.; Plesset, M. S. Phys. ReV. 1934, 46, 618.

(29) Alajar´ın, M.; Lo´pez-Leonardo, C.; Llamas-Lorente, P. Tetrahedron

Lett. 2001, 42, 605.

(30) IR absorption bands which appear in the range 900-1300 cm^-1can

be tentatively assigned to ν(PdN) and ν(PdO) of the N-phosphoryl-

iminophosphoranyl units, but they are in general overlapped by those

of the rest of the groups, and consequently, the correct assignment is

uncertain.

3300 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

Scheme 2

Scheme 3

(details are given in the Experimental Section and Table 2).³⁰

In particular, the ³¹P{¹H} NMR spectra are very informative

showing a strong downfield shift of the diphenylphosphino

group signals (ca. ∆δ 48 ppm) with respect to those shown

by the free ligands 1a,b (see Table 2). In contrast, the

(RO)₂PdO and Ph₂PdN resonances appear only slightly

shielded (∆δ -2 to -5 ppm; Table 2). ¹H and ¹³C{¹H} NMR

spectra exhibit signals in accordance with the proposed

formulations, the most significant features being those

presence of a single set of signals for the two allylic moieties

of the 2,7-dimethyl-2,6-diene-1,8-diyl ligand in the spectra

of compounds 6a,b (only five resonances are observed in

the ¹³C{¹H} NMR spectra) supports the formation of a simple

equatorial adduct [Ru(η³:η³-C₁₀H₁₆)Cl₂L] with a local C₂-

symmetry for the octadienediyl chain.³²

The structure of complex 2b has been unequivocally

confirmed by a single-crystal X-ray diffraction study. An

ORTEP view is shown in Figure 1; selected bond distances

and angles are listed in the caption and in Table 3. The

molecule exhibits a usual pseudooctahedral three-legged

piano-stool geometry around the metal with values of the

interligand angles P(1)-Ru-Cl(1), P(1)-Ru-Cl(2), and

Cl(1)-Ru-Cl(2), and those between the centroid of the arene

ring C* and the legs, typical of a pseudo-octahedron. The

most remarkable feature is that the P(2)sN(1) (1.578(4) Å)

concerning the methylenic PCH₂P group of the ligands: (i)

1

in the H NMR, a doublet of doublet resonance (²J_HP(III)

)

²J_HP(V)) 9.1-9.9 Hz) for 2a,b and two unresolved multiplets

for 6a,b (δ 3.87-4.23), and (ii) in the ¹³C{¹H} NMR, a

characteristic doublet of doublet of doublets signal in the

range 20.43-24.98 ppm (J_CP(V)) 74.7-79.4 Hz, J_CP(III)

)

15.2-19.2 Hz, ³J_CP(V)) 6.4-8.4 Hz). We note also that the

Inorganic Chemistry, Vol. 42, No. 10, 2003 3301

Cadierno et al.

the value for the P(2)-N(1)-P(3) angle (133.7(3)°), compare

well with data previously reported for iminophosphorane

derivatives of general formula R₃PdNsP(dO)(OR′)₂.^3e,34,35

(b) K²-P,O-Complexes [Ru(η⁶-p-cymene)Cl(K²-P,O-

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆] (R ) Et (3a), Ph

(3b)) and [Ru(η³:η³-C₁₀H₁₆)Cl(K²-P,O-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)][SbF₆] (R ) Et (7a), Ph (7b)). Neutral

complexes 2b and 6a,b react with a stoichiometric amount

of silver hexafluoroantimonate, in dichloromethane at room

temperature, to give the cationic derivatives [Ru(η⁶-p-

cymene)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OPh)₂}Ph₂)]-

[SbF₆] (3b; Scheme 2) and [Ru(η³:η³-C₁₀H₁₆)Cl(κ²-P,O-

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆] (R ) Et (7a), Ph

(7b); Scheme 3), respectively, which are readily formed (84-

91% yield) via selective intramolecular O-coordination of

the phosphoryl group. In contrast, an inseparable mixture

containing complexes [Ru(η⁶-p-cymene)Cl(κ²-P,O-Ph₂PCH₂P-

{dNP(dO)(OEt)₂}Ph₂)][SbF₆] (3a) and [Ru(η⁶-p-cymene)-

Cl(κ²-P,N-Ph₂PCH₂P{dNP(dO)(OEt)₂}Ph₂)][SbF₆] (4a) (ca.

3:1 ratio) was obtained, under the same reaction conditions,

starting from 2a (Scheme 2).³⁶Alternatively, 3a/4a, 3b, and

7a,b can be prepared in similar yields directly from dimers

[{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂] and [{Ru(η³:η³-C₁₀H₁₆)(µ-Cl)-

Cl}₂], respectively, by treatment with 2 equiv of 1a,b and

AgSbF₆in dichloromethane (see Schemes 2 and 3).

Figure 1. ORTEP-type view of the structure of [Ru(η⁶-p-cymene)Cl₂-

(κ¹-P-Ph₂PCH₂P{dNP(dO)(OPh)₂}Ph₂)] (2b) showing the crystallographic

labeling scheme. Hydrogen atoms are omitted for clarity, and only the ipso-

carbons of the phenyl rings of the Ph₂P groups are shown. Thermal ellipsoids

are drawn at 30% probability level. Selected bond lengths (Å) and angles

(deg) involving the Ru atom: Ru-C* ) 1.6969(48); Ru-Cl(1) )

2.4249(12); Ru-Cl(2) ) 2.4140(12); Ru-P(1) ) 2.3467(13); C*-Ru-

Cl(1) ) 125.38(18); C*-Ru-Cl(2) ) 125.96(17); C*-Ru-P(1) )

131.76(17); P(1)-Ru-Cl(1) ) 86.69(4); P(1)-Ru-Cl(2) ) 83.07(4);

Cl(1)-Ru-Cl(2) ) 89.87(4); Ru-P(1)-C(11) ) 111.04(17); Ru-P(1)-

C(36) ) 115.36(16); Ru-P(1)-C(42) ) 112.88(16). C* ) centroid of the

p-cymene ring (C(1), C(2), C(3), C(4), C(5), C(6)).

Conductance measurements in acetone confirm that com-

pounds 3a,b and 7a,b are 1:1 electrolytes (Λ_M) 102-122

Ω^-1cm²mol^-1). Their NMR spectroscopic data (see the

Experimental Section and Table 2 for details) provide

significant structural information.³⁰Thus, in the ³¹P{¹H}

NMR spectra the κ²-P,O-chelating coordination of 1a,b is

marked by a slight downfield shift (ca. ∆δ 7 ppm) in the

2

(RO)₂PdO group resonances (δ -1.88-9.49; d, J_PP

)

Table 3. Selected Bond Lengths and Angles for the

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂Unit in Complexes 2b, 3b, 7a, and 12b

37.0-49.5 Hz) with respect to the parent compounds 2a,b

2b

3b

7a

12b

(33) Although P-N single bonds frequently display distances (1.64-1.77

Å) bordering on the range for double bonds (1.45-1.62 Å), the P(3)-

N(1) bond length found in the structure of complex 2b is remarkably

very low. See for example: (a) Abel, E. W.; Mucklejohn, S. A.

Phosphorus Sulfur Relat. Elem. 1981, 9, 235. (b) Niecke, E.; Gudat,

D. Angew. Chem., Int. Ed. Engl. 1991, 30, 217. (c) Witt, M.; Roesky,

H. W. Chem. ReV. 1994, 94, 1163. (d) Bhattacharyya, P.; Woollins,

J. D. Polyhedron 1995, 14, 3367. (e) Woollins, J. D. J. Chem. Soc.,

Dalton Trans. 1996, 2893. (f) Ly, T. Q.; Woollins, J. D. Coord. Chem.

ReV. 1998, 176, 451. (g) Dehnicke, K.; Krieger, M.; Massa, W. Coord.

Chem. ReV. 1999, 182, 19.

Bond Lengths (Å)

P(1)-C(11)

C(11)-P(2)

P(2)-N(1)

N(1)-P(3)

P(3)-O(1)

P(3)-O(2)

P(3)-O(3)

1.846(5)

1.802(5)

1.578(4)

1.569(4)

1.467(3)

1.611(4)

1.601(3)

1.836(5) 1.858(4)

1.799(5) 1.821(4)

1.550(5) 1.560(3)

1.552(5) 1.585(4)

1.474(4) 1.488(3)

1.587(4) 1.557(3)

1.588(4) 1.574(3)

1.846(5)

1.792(5)

1.577(5)

1.588(4)

1.466(3)

1.606(4)

1.598(4)

Bond Angles (deg)

(34) See for example: (a) Larre´, C.; Donnadieu, B.; Caminade, A. M.;

Majoral, J. P. Eur. J. Inorg. Chem. 1999, 601. (b) Balakrishna, M. S.;

Abhyankar, R. M.; Walawalker, M. G. Tetrahedron Lett. 2001, 42,

2733. (c) Longlet, J. J.; Bodige, S. G.; Watson, W. H.; Nielson, R. H.

Inorg. Chem. 2002, 41, 6507.

(35) Similar PdN bond lengths and PdNsC_aromangles have been reported

for iminophosphorane-phosphine ligands Ph₂PCH₂P(dNR)Ph₂con-

taining π-acceptor fluoroaromatic substituents. See for example: (a)

Katti, K. V.; Santarsiero, B. D.; Pinkerton, A. A.; Cavell, R. G. Inorg.

Chem. 1993, 32, 5919. (b) Li, J.; McDonald, R.; Cavell, R. G.

Organometallics 1996, 15, 1033.

P(1)-C(11)-P(2)

C(11)-P(2)-N(1)

120.9(3)

114.2(2)

119.7(3) 123.7(2)

123.3(3)

117.2(2) 115.89(18) 110.0(2)

108.1(3) 109.63(19) 102.3(2)

104.4(3) 106.12(18) 105.5(2)

147.7(3) 134.5(2)

120.9(2) 116.07(18) 119.7(2)

C(11)-P(2)-C(24) 108.1(2)

C(11)-P(2)-C(30) 104.2(2)

P(2)-N(1)-P(3)

N(1)-P(3)-O(1)

N(1)-P(3)-O(2)

N(1)-P(3)-O(3)

O(1)-P(3)-O(2)

O(1)-P(3)-O(3)

O(2)-P(3)-O(3)

133.7(3)

122.9(2)

128.6(3)

103.95(19) 105.7(3) 107.55(18) 102.8(2)

104.97(19) 109.7(3) 112.51(19) 107.8(2)

111.55(19) 112.4(2) 109.12(16) 113.0(2)

107.51(19) 102.6(2) 108.63(17) 113.0(2)

104.43(19) 104.6(2) 101.98(17) 97.7(2)

(36) Variable-temperature ³¹P{¹H} NMR experiments were carried out with

CD₂Cl₂(from 20 to -80 °C), CD₃NO₂(from 20 to 80 °C), and CD₃-

CN (from -40 to 80 °C) solutions of this mixture. While no changes

in the 3a/4a ratio (ca. 3:1) could be detected in the case of CD₂Cl₂

and CD₃NO₂, this ratio was found to be temperature dependent when

acetonitrile was used as solvent (ca. 1:1 and 7:1 at -40 and 80 °C,

respectively). This fact, which is in accord with the theoretical

calculations, seems to indicate the existence of a dynamic equilibrium

between both species in solution. Isomerizations between the κ²-P,

N- and κ²-P, O-isomers evidence the hemilabile properties of imino-

phosphorane-phosphine ligands 1a,b.

and P(3)sN(1) (1.569(4) Å) bond lengths are quite similar

although the former is a double PdN bond.³³This fact can

be explained on the basis of the strong π-acceptor nature of

the phosphoryl group which imposes delocalization of the

lone pair of electrons on nitrogen through the sPh₂PdNs

P(dO)(OPh)₂framework. These bond distances, as well as

3302 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

Figure 2. ORTEP-type view of the structure of the cation [Ru(η⁶-p-

cymene)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OPh)₂}Ph₂)]⁺(3b) showing the

crystallographic labeling scheme. Hydrogen atoms are omitted for clarity,

and only the ipso-carbons of the phenyl rings of the Ph₂P groups are shown.

Thermal ellipsoids are drawn at 20% probability level. Selected bond lengths

(Å) and angles (deg) involving the Ru atom: Ru-C* ) 1.697(6);

Ru-O(1) ) 2.116(3); Ru-Cl(1) ) 2.3982(16); Ru-P(1) ) 2.3775(14);

C*-Ru-O(1) ) 123.5(2); C*-Ru-Cl(1) ) 126.8(2); C*-Ru-P(1) )

130.1(2); O(1)-Ru-P(1) ) 88.77(10); O(1)-Ru-Cl(1) ) 86.22(12); P(1)-

Ru-Cl(1) ) 87.93(5); Ru-P(1)-C(11) ) 116.10(19); Ru-P(1)-C(36)

Figure 3. ORTEP-type view of the structure of the cation [Ru(η³:η³-

C₁₀H₁₆)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OEt)₂}Ph₂)]⁺(7a) showing the

crystallographic labeling scheme. Hydrogen atoms are omitted for clarity,

and only the ipso-carbons of the phenyl rings of the Ph₂P groups are shown.

Thermal ellipsoids are drawn at 20% probability level. Selected bond lengths

(Å) and angles (deg) involving the Ru atom: Ru-C(1) ) 2.227(4); Ru-

C(2) ) 2.304(4); Ru-C(4) ) 2.309(4); Ru-C(7) ) 2.265(4); Ru-C(8) )

2.297(4); Ru-C(10) ) 2.232(4); Ru-C* ) 2.0317(44); Ru-C** )

2.0178(42); Ru-P(1) ) 2.4288(12); Ru-O(1) ) 2.128(3); Ru-Cl(1) )

2.3960(13); C*-Ru-C** ) 129.68(17); C*-Ru-O(1) ) 88.93(16); C**-

Ru-O(1) ) 89.91(15); C*-Ru-Cl(1) ) 88.89(14); C**-Ru-Cl(1) )

95.94(14); C*-Ru-P(1) ) 114.01(14); C**-Ru-P(1) ) 116.31(13);

O(1)-Ru-P(1) ) 91.91(8); O(1)-Ru-Cl(1) ) 173.80(8); P(1)-Ru-Cl-

(1) ) 83.69(5); Ru-P(1)-C(11) ) 115.21(13); Ru-P(1)-C(36) )

119.73(14); Ru-P(1)-C(42) ) 114.35(14); P(3)-O(1)-Ru ) 143.89(18).

C* and C** ) centroids of the allyl units (C(1), C(2), C(4) and C(7), C(8),

C(10), respectively).

)

113.97(18); Ru-P(1)-C(42) ) 117.25(18); P(3)-O(1)-Ru )

144.7(2). C* ) centroid of the p-cymene ring (C(1), C(2), C(3), C(4), C(5),

C(6)).

and 6a,b, respectively (see Table 2). The chemical shifts of

the Ph₂PdN and Ph₂P groups are almost unaffected by the

2

ring closure (δ 9.20-11.82 (d, J_PP) 37.0-49.5 Hz) and

22.22-24.86 (s), respectively; Table 2).³⁷In contrast to 2a,b

and 6a,b, the PCH₂P carbon resonates in the ¹³C{¹H} NMR

spectra as a doublet of doublets (δ 28.27-33.68) due to the

exclusive coupling with the phosphorus atoms of the

Ph₂PdN (J_CP) 54.0-57.1 Hz) and Ph₂P (J_CP) 8.9-15.8

Hz) units. We note also that, as a consequence of the

stereogenicity of the ruthenium atom, the methylenic PCH₂P

protons are, in all the cases, chemically inequivalent appear-

ing as two unresolved multiplets in the range 3.09-5.17 ppm.

The molecular structures of 3b and 7a have been con-

firmed by X-ray diffraction.¹²ORTEP plots are shown in

Figures 2 and 3, respectively; selected bonding parameters

appear in the captions and in Table 3. While 3b exhibits the

expected pseudooctahedral three-legged piano-stool geometry

around the metal, the structure of 7a can be described as a

distorted trigonal bipyramid (TBPY) by considering the allyl

groups as monodentate ligands bound to ruthenium through

their centers of mass (C* and C**; see caption for Figure

3), in which C*, C**, and P(1) occupy the equatorial sites

and Cl(1) and O(1) the axial sites.³⁸Remarkably, no

appreciable changes are observed in the bond distances along

the PdNsPdO unit in 3b as compared to its precursor 2b

(i.e., P(2)sN(1) ) 1.550(5) Å vs 1.578(4) Å; N(1)sP(3) )

1.552(5) Å vs 1.569(4) Å; P(3)sO(1) ) 1.474(3) Å vs

1.467(3) Å; similar bond distances have been found in the

structure of 7a; see Table 3), the elongation of the PdNsP

angle (147.7(3)° vs 133.7(3)°) being the most significant

difference between both structures. It seems to indicate that

the electronic delocalization of the nitrogen lone pair is

(38) The allyl groups of the 2,7-dimethyl-2,6-diene-1,8-diyl ligand are both

η³-bound to the ruthenium atom with Ru-C distances in the range

2.227(4)-2.309(4) Å (see caption for Figure 3). These values, together

with the C-C distances (1.392(7)-1.417(6) Å) and the internal

C-C-C angles (114.9(4)° and 116.2(5)°) within the allyl groups

(details are given in the Supporting Information), are similar to those

found in related complexes containing the [Ru(η³:η³-C₁₀H₁₆)] fragment.

See for example: (a) Hitchcock, P. B.; Nixon, J. F.; Sinclair, J. J.

Organomet. Chem. 1975, 86, C34. (b) Toerien, J. G.; van Rooyen, P.

H. J. Chem. Soc., Dalton Trans. 1991, 1563. (c) Cox, D. N.; Small,

R. W. H.; Roulet, R. J. Chem. Soc., Dalton Trans. 1991, 2013. (d)

Toerien, J. G.; van Rooyen, P. H. J. Chem. Soc., Dalton Trans. 1991,

2693. (e) Steed, J. W.; Tocher, D. A. J. Chem. Soc., Dalton Trans.

1992, 459. (f) Steed, J. W.; Tocher, D. A. J. Chem. Soc., Dalton Trans.

1992, 2765. (g) Kavanagh, B.; Steed, J. W.; Tocher, D. A. J. Chem.

Soc., Dalton Trans. 1993, 327. (h) Belchem, G.; Steed, J. W.; Tocher,

D. A. J. Chem. Soc., Dalton Trans. 1994, 1949.

(37) These chemical shifts contrast with those found for κ²-P,N-isomer 4a

2

3

(δ 10.24 (dd, J_PP) 6.1 Hz, J_PP) 6.1 Hz, (EtO)₂PdO), 47.22 (dd,

²J_PP) 20.2 Hz, ³J_PP) 6.1 Hz, Ph₂P), and 58.68 (dd, ²J_PP) 20.2 and

6.1 Hz, Ph₂PdN)). The highly deshielded chemical shifts observed

for the Ph₂PdN and Ph₂P groups in 4a compare well with those

recently reported for related [Ru(η⁶-arene)Cl{κ²-P,N-Ph₂PCH₂P-

(dNR)Ph₂}]⁺complexes (see ref 5). Deshielding due to phosphorus

incorporation into five-membered ring systems is a common trend in

transition-metal complexes containing chelating P-donor ligands:

Garrou, P. E. Chem. ReV. 1981, 81, 229.

Inorganic Chemistry, Vol. 42, No. 10, 2003 3303

Cadierno et al.

Table 4. Calculated Total (hartree) and Relative (kcal/mol) Energies

for the Model Complexes

[Ru(η⁶-C₆H₆)Cl(κ²-P,N-H₂PCH₂P{dNP(dO)(OH)₂}H₂)]⁺(A) and

[Ru(η⁶-C₆H₆)Cl(κ²-P,O-H₂PCH₂P{dNP(dO)(OH)₂}H₂)]⁺(B)^a

B3LYP/DZV(d)

MP2/DZV(d)

A

B

-683.690437 (0.0)

-683.680498 (6.2)

-680.855667 (0.0)

-680.837274 (11.5)

^aB3LYP/DZV(d)-optimized geometries.

experimentally obtained for 3b by X-ray diffraction, deviat-

ing only ca. 0.1 Å (see captions for Figures 2 and 4, and

Table 3). The calculated bond angle values within the seven-

membered ring in B are also in accordance with those found

in 3b with the exception of the angles P₂sNsP₃(118.3° vs

147.7(3)°) and P₃sOsRu (128.0° vs 144.7(2)°). These

differences are probably due to the replacement of the phenyl

groups (3b) in the phosphoryl unit by hydrogens (B).⁴¹

The absolute and relative energies of A and B are given

in Table 4. According to our calculations, A should be 6.2

kcal/mol more stable than B at the B3LYP/DZV(d)//B3LYP/

DZV(d) level. Moreover, inclusion of correlation increases

this energy gap to 11.5 kcal/mol [MP2/DZV(d)//B3LYP/

DZV(d) level]. These values deserve noting. There is a

general opinion that decreases in complex stability associated

with increases in the size of the chelate ring are due to steric

strain effects on the metal.⁴⁰Steric strain exists in a molecule

when bonds are forced to make abnormal angles, which

results in higher energy than would be the case in the absence

of angle distortions. The interligand angles P₁-Ru-Cl

(82.5°), P₁-Ru-O (91.8°), and O-Ru-Cl (86.3°) in model

B and P₁-Ru-Cl (80.0°), P₁-Ru-N (80.2°), and N-Ru-

Cl (84.7°) in model A present typical values for pseudo-

octahedral three-legged piano-stool geometries. This seems

to indicate a very similar strain energy for both complexes.

On the other hand, looking at the geometrical parameters, it

can be observed that Ru-L distances are larger for donor

ligands in A than in B (Ru-Cl, from 2.496 to 2.484 Å;

average Ru-C_arene, from 2.272 to 2.260 Å) and shorter for

the σ-donor-π-acceptor phosphine ligand (Ru-P₁, from

2.444 to 2.464 Å). These values may be explained by taking

into account the larger electron-donor ability of nitrogen

compared to oxygen, which is probably the reason for the

greater stability of A.

Figure 4. Computer plot of the B3LYP/DZV(d) optimized structutes for

the model complexes [Ru(η⁶-C₆H₆)Cl(κ²-P,N-H₂PCH₂P{dNP(dO)(OH)₂}-

H₂)]⁺(A) and [Ru(η⁶-C₆H₆)Cl(κ²-P,O-H₂PCH₂P{dNP(dO)(OH)₂}H₂)]⁺

(B). Selected bond lengths (Å) and angles (deg) for model A: Ru-P₁)

2.444; P₁-C ) 1.905; C-P₂) 1.872; P₂-N ) 1.702; N-Ru ) 2.173;

Ru-Cl ) 2.496; average Ru-C_arene) 2.272; Ru-P₁-C ) 107.6; P₁-

C-P₂) 107.6; C-P₂-N ) 107.4; P₂-N-Ru ) 117.3; P₁-Ru-N ) 80.2;

P₁-Ru-Cl ) 80.0; N-Ru-Cl ) 84.7. For model B: Ru-P₁) 2.464;

P₁-C ) 1.900; C-P₂) 1.877; P₂-N ) 1.678; N-P₃) 1.658; P₃-O )

1.567; O-Ru ) 2.154; Ru-Cl ) 2.484; average Ru-C_arene) 2.260; Ru-

P₁-C ) 118.5; P₁-C-P₂) 112.4; C-P₂-N ) 115.6; P₂-N-P₃) 118.3;

N-P₃-O ) 115.7; P₃-O-Ru ) 128.0; P₁-Ru-O ) 91.8; P₁-Ru-Cl )

82.5; O-Ru-Cl ) 86.3.

maintained upon coordination of the phosphoryl unit to the

metal.^3eThe RusO(1) bond length (3b, 2.116(3) Å; 7a,

2.128(3) Å) compares well to that shown by ruthenium

complexes containing O-coordinated phosphine-oxides.³⁹

Theoretical Studies. It is interesting to note the observed

preference for the κ²-P,O- vs κ²-P,N-coordination (i.e., seven-

membered vs five-membered rings) of 1a,b. This is in sharp

contrast with the well-known fact of coordination chemistry

establishing that an increase in the size of a chelate ring

usually leads to a drop in complex stability.⁴⁰In fact,

analogous ((iminophosphoranyl)amino)phosphine ligands

Ph₂PN(R)P{dNP(dO)(OPh)₂}Ph₂(R ) Me, Et) are able to

form typical κ²-P,N-five-membered chelate rings.^3eIn order

to evaluate to what extent electronic effects are responsible

for this unexpected behavior, we thought it to be of interest

to study theoretically their relative stability. To the best of

our knowledge, no ab initio calculations on transition-metal

complexes bearing iminophosphorane-phosphine ligands

have been reported to date.

The size of the complexes to be studied required the use

of models for the calculations. Thus, [Ru(η⁶-C₆H₆)Cl(κ²-P,N-

H₂PCH₂P{dNP(dO)(OH)₂}H₂)]⁺(A) was used for the five-

membered ring and [Ru(η⁶-C₆H₆)Cl(κ²-P,O-H₂PCH₂-

P{dNP(dO)(OH)₂}H₂)]⁺(B) for the seven-membered (Fig-

ure 4). The relevant geometrical parameters of the optimized

structures with the B3LYP/DZV(d) wave function are given

in the caption. The A and B structures were characterized

as minima on the potential energy surface. The optimized

bond distances for B are in good agreement with those

The experimental preference observed for the κ²-P,O-

versus the κ²-P,N-coordination of 1a,b in these ruthenium

fragments must, therefore, be explained on the basis of steric

effects. As can be appreciated in Figure 4, the formation of

a five-membered metallacycle (A) results in a higher steric

hindrance between the phosphoryl group substituents and the

substituents of the η⁶-coordinated arene ring when compared

to model B. This fact is in accord with the formation of the

κ²-P,N-isomer 4a which is only observed when the bulky

phenyl groups are replaced by ethyls (see Scheme 2). This

steric hindrance, which seems to increase in the case of the

(η³:η³-octadienediyl)-ruthenium(IV) fragment since no κ²-

(39) See for example: (a) Faller, J. W.; Patel, B. P.; Albrizzio, A.; Curtis,

M. Organometallics 1999, 18, 3096. (b) Faller, J. W.; Parr, J.

Organometallics 2000, 19, 1829. (c) Faller, J. W.; Grimmond, B. J.;

Curtis, M. Organometallics 2000, 19, 5174.

(40) See for example: (a) Hancock, R. D.; Martell, A. E. Comments Inorg.

Chem. 1988, 6, 237. (b) Hancock, R. D.; Martell, A. E. Chem. ReV.

1989, 89, 1875. (c) Hancock, R. D.; Martell, A. E. In Coordination

Chemistry: A Century of Progress; Kauffman, G. B., Ed.; ACS

Symposium Series 565; American Chemical Society: Washington, DC,

1994; p 251.

(41) In 3b, the steric hindrance between the Ph groups, which participate

in the electronic delocalization along the PdNsPdO-Ru fragment,

and the η⁶-arene substituents seems to be reflected in the elongation

of these angles.

3304 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

Scheme 4

P,N-coordination of 1a is observed (Scheme 3), is probably

the reason for the experimental preference of the κ²-P,O-

bidentate coordination of 1a,b.

ligands. ¹H and ¹³C{¹H} NMR spectra are also in accordance

with the proposed formulations (see the Experimental Sec-

tion).³⁰In particular, the methylenic PCH₂P proton and

carbon resonances appear at 2.78-5.02 ppm (two unresolved

multiplets) and 26.69-39.72 ppm (ddd or dd (for 5a); J_CP(V)

(c) K³-P,N,O-Complexes [Ru(η⁶-p-cymene)(K³-P,N,O-

Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂(R ) Et (5a), Ph

(5b)) and [Ru(η³:η³-C₁₀H₁₆)(K³-P,N,O-Ph₂PCH₂P{dNP-

(dO)(OR)₂}Ph₂)][SbF₆]₂(R ) Et (8a), Ph (8b)). Treatment

of neutral complexes 2a,b and 6a,b with a 2-fold excess of

AgSbF₆, in dichloromethane at room temperature, leads to

the formation of the dicationic derivatives [Ru(η⁶-p-cymene)-

(κ³-P,N,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂(R ) Et

(5a), Ph (5b)) and [Ru(η³:η³-C₁₀H₁₆)(κ³-P,N,O-Ph₂PCH₂P-

{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂(R ) Et (8a), Ph (8b)),

respectively, via coordination of both the iminophosphorane

and phosphoryl groups (77-93% yield; see Schemes 2 and

3). These complexes can be also prepared in similar yields

from 3a/4a, 3b, and 7a,b by reaction with 1 equiv of AgSbF₆

in dichloromethane at room temperature. In contrast to their

neutral or cationic precursors, 5a,b and 8a,b are moisture

sensitive both in solution and in the solid state, slowly

generating complicated mixtures of uncharacterized prod-

ucts.⁴²

3

) 63.1-90.8 Hz, J_CP(III)) 13.0-23.4 Hz, J_CP(V)) 7.2-

8.1 Hz), respectively.

Reactivity Studies: Synthesis of [Ru(η⁶-p-cymene)X₂-

(K¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] (R ) Et, X ) Br

(9a), I (10a), N₃(11a), NCO (12a); R ) Ph, X ) Br (9b),

I (10b), N₃(11b), NCO (12b)). Taking advantage of the

hemilabile properties of iminophosphorane-phosphine ligands

1a,b both in their κ²-P,O-, κ²-P,N-, and κ³-P,N,O-coordina-

tion modes,^36,43we decided to explore the reactivity of

complexes 3a/4a, 3b, and 5a,b toward a series of anionic

ligands. Thus, we have found that by treating complex 3b,

or a mixture containing compounds 3a/4a, with an excess

-

(ca. 10 equiv) of sodium salts NaX (X^-) Cl^-, Br^-, I^-, N₃,

NCO^-), in methanol at room temperature, the neutral

derivatives [Ru(η⁶-p-cymene)X₂(κ¹-P-Ph₂PCH₂P{dNP(dO)-

(OEt)₂}Ph₂)] (2a,b, 9-12a,b) are formed (77-85% yield)

via chelate ring opening and, in the case of 9-12a,b,

concomitant chloride metathesis (Scheme 4). As expected,

Conductance values for 5a,b and 8a,b in acetone reflect

that these complexes are 2:1 electrolytes (Λ_M) 177-198

Ω^-1cm²mol^-1). The coordination of the iminophosphorane

group to ruthenium is confirmed in the ³¹P{¹H} NMR spectra

by the presence of characteristic downfield resonances of

(42) The instability of these complexes in solution prevented their crystal-

lization. A reviewer has brought to our attention that probably water

coordinates to the metal upon decoordination of the PdN unit in

complexes 5a,b and 8a,b. Coordination of water on oxophilic

ruthenium complexes containing P,N-donor ligands has been recently

reported. See, for instance: Stoop, R. M.; Bachmann, S.; Valentini,

M.; Mezzetti, A. Organometallics 2000, 19, 4117. Bachmann, S.;

Furler, M.; Mezzetti, A. Organometallics 2001, 20, 2102. All attempts

to obtain stable complexes by treatment of dichloromethane solutions

of 5a,b and 8a,b with water failed.

the Ph₂PdN (δ 50.88-55.62; dd or d (for 5b), ²J_PP) 9.0-

2

36.3 and 3.8-8.1 Hz) and Ph₂P (δ 41.68-46.64; d, J_PP

)

9.0-36.3 Hz) groups (see Table 2).³⁷The phosphorus nucleus

of the (RO)₂PdO unit in 5a,b resonates at 18.28 (d, ²J_PP

)

3.8 Hz) and 6.33 (s) ppm, respectively, also in agreement

with its coordination to the metal. In contrast, the chemical

shifts found for the (RO)₂PdO fragments in 8a,b (8a, 4.45

ppm (d, ²J_PP) 6.5 Hz); 8b, -6.47 ppm (d, ²J_PP) 8.1 Hz))

are closer to those observed for 6a,b (in which these groups

are not bound to ruthenium) than those for 7a,b (see Table

2). This fact can be explained on the basis of the different

trans influence of the diphenylphosphino and chloride

(43) We note that complex [Ru(η⁶-p-cymene)(κ¹-O-Me₂CdO)(κ²-P,O-Ph₂-

PCH₂P{dNP(dO)(OEt)₂}Ph₂)][SbF₆]₂is readily formed when 5a is

dissolved in acetone as inferred by ³¹P{¹H} NMR spectroscopy which

2

shows signals at 11.43 (d, J_PP) 37.0 Hz, (EtO)₂PdO), 12.24 (d,

²J_PP) 37.0 Hz, Ph₂PdN), and 24.13 (s, Ph₂P) ppm. All attempts to

isolate this complex failed, leading instead to its precursor 5a

quantitatively after evaporation of the solvent. The reversibility of this

process evidences clearly the hemilability of the PdN unit in

complexes containing iminophosphorane-phosphine ligands 1a,b

coordinated in κ³-P,N,O-manner.

Inorganic Chemistry, Vol. 42, No. 10, 2003 3305

Cadierno et al.

Scheme 5

Table 5. Catalytic Transfer Hydrogenation of Cyclohexanone^a

c

entry

catalyst

yield (%)^b

TOF₅₀(h^-1

)

Ruthenium(II) Complexes

40 (>99)^d

1

2

3

4

5

6

2a

2b

50

26

33

12

37

10

25 (98)^d

3a/4a

3b

24 (>99)^d

15 (78)^d

5a

5b

25 (>99)^d

14 (76)^d

Ruthenium(IV) Complexes

7

8

9

10

11

12

6a

6b

7a

7b

8a

8b

>99

367

93

426

165

86

64 (>99)^e

>99

78 (>99)^e

61 (>99)^d

14 (83)^d

12

^aConditions: reactions were carried out at 82 °C using 5 mmol of

i

cyclohexanone (0.2 M in PrOH). Ketone/catalyst/NaOH ratio: 250/1/24.

^bYield of cyclohexanol after 2 h. GC determined. ^cTurnover frequencies

((mol product/mol catalyst)/time) were calculated at 50% conversion. ^dYield

after 24 h in parentheses. GC determined. ^eYield after 9 h in parentheses.

GC determined.

Figure 5. ORTEP-type view of the structure of [Ru(η⁶-p-cymene)(κ¹-N-

NCO)₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OPh)₂}Ph₂)] (12b) showing the crystal-

lographic labeling scheme. Hydrogen atoms are omitted for clarity, and

only the ipso-carbons of the phenyl rings of the Ph₂P groups are shown.

Thermal ellipsoids are drawn at 30% probability level. Selected bond lengths

(Å) and angles (deg) involving the Ru atom: Ru-C* ) 1.6925(49);

Ru-N(2) ) 2.083(4); Ru-N(3) ) 2.062(4); Ru-P(1) ) 2.358(1); C*-

Ru-N(2) ) 126.25(21); C*-Ru-N(3) ) 128.24(21); C*-Ru-P(1) )

131.04(17); Ru-N(2)-C(48) ) 159.4(5); Ru-N(3)-C(49) ) 173.7(6);

N(2)-Ru-N(3) ) 86.46(19); P(1)-Ru-N(2) ) 85.32(12); P(1)-Ru-N(3)

hydrogenation of cyclohexanone by propan-2-ol (Scheme 5).

For comparative purposes, the activity of ruthenium(IV)

complexes 6a,b, 7a,b, and 8a,b has also been examined. In

a typical experiment, the ruthenium catalyst precursor (0.4

mol %) and NaOH (9.6 mol %) were added to a 0.2 M

i

solution of cyclohexanone in PrOH at 82 °C, the reaction

)

84.20(12); Ru-P(1)-C(11) ) 108.82(15); Ru-P(1)-C(36) )

being monitored by gas chromatography. Selected results are

shown in Table 5.

115.97(17); Ru-P(1)-C(42) ) 111.93(15). C* ) centroid of the p-cymene

ring (C(1), C(2), C(3), C(4), C(5), C(6)).

All the complexes studied have proven to be active and

efficient catalysts leading to nearly quantitative conversions

of cyclohexanone into cyclohexanol, with the cationic

derivative [Ru(η³:η³-C₁₀H₁₆)Cl(κ²-P,O-Ph₂PCH₂P{dNP-

(dO)(OEt)₂}Ph₂)][SbF₆] (7a) showing the highest activity

(TOF₅₀of 426 h^-1; entry 9). The following features are worth

noting: (a) The catalytic performances shown by the bis-

(allyl)-ruthenium(IV) complexes are in all the cases higher

than those of their corresponding (η⁶-p-cymene)-ruthenium-

(II) counterparts (see entries 1-6 vs 7-12).⁴⁶These results

are promising since, as far as we know, this is the first time

that ruthenium(IV) complexes have been used in this type

complexes 9-12a,b are also formed starting from the

dicationic complexes 5a,b (Scheme 4).

Analytical and spectroscopic data (IR and ¹H, ³¹P{¹H} and

¹³C{¹H} NMR) for 9-12a,b strongly support the proposed

formulations being comparable to those observed in mono-

dentate complexes 2a,b (see the Experimental Section and

Table 2).³⁰Moreover, the structure of complex 12b has been

confirmed by single-crystal X-ray diffraction studies (see

Figure 5 and Table 3). Since the structural parameters at the

[Ru(η⁶-p-cymene)(κ¹-P-Ph₂PCH₂P{dNP(dO)(OPh)₂}-

Ph₂)] fragment are quite similar to those observed for 2b

(see Figure 1 and Table 3), they are not worth further

discussion. The two cyanate ligands are N-bound to ruthe-

nium in a nearly linear fashion (Ru-N(2)-C(48) )

159.4(5)°, N(2)-C(48)-O(4) ) 178.6(6)°, Ru-N(3)-C(49)

) 173.7(6)°, N(3)-C(49)-O(5) ) 177.7(12)°) showing

bond lengths of Ru-N(2) ) 2.083(4) Å, N(2)-C(48) )

1.150(7) Å, C(48)-O(4) ) 1.213(6) Å, Ru-N(3) )

2.062(4) Å, N(3)-C(49) ) 1.088(8) Å, and C(49)-O(5) )

1.190(9) Å.⁴⁴

(44) Although the cyanate ion can potentially act as an ambidentate ligand,

it tends to exhibit only the N-bonding when coordinated as a

monodentate ligand to a transition-metal. For reviews see: (a) Norbury,

A. H. AdV. Inorg. Chem. Radiochem. 1975, 17, 231. (b) Burmeister,

J. L. Coord. Chem. ReV. 1990, 105, 77. In our case, since N and O

have very similar sizes and scattering factors, both the N- and

O-bonded models were refined to convergence, and the former gave

significantly lower residuals (R ) 0.0385 and R_w) 0.1070 as against

R ) 0.0400 and R_w) 0.1121). This fact, along with the linearity of

the Ru-N-C-O chains, confirms the N-coordination of the cyanato

ligands in 12b.

(45) For reviews on transition-metal catalyzed transfer hydrogenation of

ketones see: (a) Zassinovich, G.; Mestroni, G.; Gladiali, S. Chem.

ReV. 1992, 92, 1051. (b) Noyori, R.; Hashiguchi, S. Acc. Chem. Res.

1997, 30, 97. (c) Palmer, M. J.; Wills, M. Tetrahedron: Asymmetry

1999, 10, 2045. (d) Noyori, R.; Yamakawa, M.; Hashiguchi, S. J. Org.

Chem. 2001, 66, 7931. (e) Ba¨ckvall, J. E. J. Organomet. Chem. 2002,

652, 105. (f) Carmona, D.; Lamata, M. P.; Oro, L. A. Eur. J. Inorg.

Chem. 2002, 2239.

Catalytic Transfer Hydrogenation of Cyclohexanone.

The well-known ability of ruthenium(II) species to act as

efficient catalysts in hydrogen transfer reactions between

alcohols and ketones⁴⁵prompted us to study the catalytic

activity of complexes 2a,b, 3a/4a, 3b, and 5a,b in transfer

3306 Inorganic Chemistry, Vol. 42, No. 10, 2003

Ru Complexes with Iminophosphorane-Phosphines

of catalytic transformation.⁴⁵(b) Both in the Ru(II) and

Ru(IV) series those catalysts containing the ligand 1a (R )

Et) are more effective than those containing 1b (R ) Ph)

(see odds vs evens entries). Since coordination of the

substrate to the metal is generally proposed during the

catalytic cycle,⁴⁷this difference is most probably due to steric

effects, the approach of cyclohexanone to ruthenium being

facilitated when the phenyl substituents on the phosphoryl

unit are replaced by the smaller ethyl groups. Also, (c) there

is no direct relationship between the catalytic activity and

the coordination mode of the ligands. Thus, while for the

ruthenium(II) series the neutral κ¹-P-complexes are the most

active (entries 1 vs 3 and 5, and 2 vs 4 and 6), the cationic

κ²-P,O-derivatives show the highest rate in the ruthenium-

(IV) series (entries 9 vs 7 and 11, and 10 vs 8 and 12).

Finally, with regard to comparative catalytic performance

with respect to other ruthenium complexes containing P,N,O-

donor ligands, the efficiencies found are unfortunately lower

than those of neutral octahedral ruthenium(II) complexes

[RuCl₂(PPh₃)(κ³-P,N,O-L)] (L ) Ph₂PCH(2-Py)CH₂OR

(R ) ethyl, menthyl; Py ) pyridyl)) reported by Mathieu

and co-workers.⁴⁸

(κ²-P,N-Ph₂PCH₂P{dNP(dO)(OEt₂)}Ph₂)][SbF₆] (4a); (d)

κ³-P,N,O-, i.e., [Ru(η⁶-p-cymene)(κ³-P,N,O-Ph₂PCH₂P-

{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂(5a,b) and [Ru(η³:η³-C₁₀H₁₆)-

(κ³-P,N,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆]₂(8a,b).

Theoretical calculations (DFT level) on the models [Ru(η⁶-

C₆H₆)Cl(κ²-P,N-H₂PCH₂P{dNP(dO)(OH)₂}H₂)]⁺(A) and

[Ru(η⁶-C₆H₆)Cl(κ²-P,O-H₂PCH₂P{dNP(dO)(OH)₂}H₂)]⁺(B)

show that the κ²-P,N-isomer A is ca. 11.5 kcal/mol more

stable than B. This contrasts with the experimental results

since seven-membered chelate rings (κ²-P,O-complexes) are

obtained preferentially. The apparent discrepancy arises

probably from the steric hindrance between the phosphoryl

group substituents and the η⁶-p-cymene or η³:η³-octadiene-

diyl ligands in the five-membered chelates (κ²-P,N-com-

plexes). The preference observed for the κ²-P,N-coordination

in the theoretical calculations is mostly a consequence of

the greater bond energy of the Ru-N bond versus the

corresponding Ru-O.

The potential hemilabile properties of iminophosphorane-

phosphines 1a,b have been proven in the reactivity of the

chelate κ²-P,O-, κ²-P,N-, and κ³-P,N,O-complexes. This has

allowed the synthesis of κ¹-P-derivatives [Ru(η⁶-p-cymene)-

X₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] (R ) Et, Ph;

X ) Br, I, N₃, NCO; 9-12a,b), in excellent yields and under

very mild reaction conditions, by treatment of 3a/4a and 3b

with the appropriate anionic ligand X^-via chelate ring

opening and concomitant chloride metathesis. By monitoring

the course of these reactions by ³¹P{¹H} NMR spectroscopy,

we observed that the latter process is slightly slower than

the former since, besides the signals of 3a/4a-3b and

9-12a,b, resonances attributable to neutral species [Ru(η⁶-

p-cymene)ClX(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)] could

be observed. In accord with this observation, we found that

complexes 9-12a,b are formed faster (2 h vs 4 h), under

the same reaction conditions, starting from the dicationic

complexes 5a,b (see Scheme 4). In addition, compounds

2-8a,b have proven to be suitable catalyst precursors for

the transfer hydrogenation of cyclohexanone by propan-2-

ol (see Scheme 5). Further studies devoted to the application

of these P,N,O-ligands in other catalytic transformations are

now in progress.

Conclusions

Novel heterotrifunctional ligands Ph₂PCH₂P{dNP(dO)-

(OR)₂}Ph₂(1a,b) showing a P,N,O-donor framework have

been easily prepared via single-stage oxidation of bis-

(diphenylphosphino)methane with phosphoryl azides (RO)₂P-

(dO)N₃(R ) Et, Ph). These ligands show a versatile

coordination ability in ruthenium fragments derived from the

readily available ruthenium(II) and ruthenium(IV) chloro-

bridged dimers [{Ru(η⁶-p-cymene)(µ-Cl)Cl}₂] and [{Ru-

(η³:η³-C₁₀H₁₆)(µ-Cl)Cl}₂], respectively. Thus, the following

coordination modes have been observed: (a) κ¹-P-, i.e., [Ru-

(η⁶-p-cymene)Cl₂(κ¹-P-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)]

(2a,b) and [Ru(η³:η³-C₁₀H₁₆)Cl₂(κ¹-P-Ph₂PCH₂P{dNP(dO)-

(OR)₂}Ph₂)] (6a,b); (b) κ²-P,O-, i.e., [Ru(η⁶-p-cymene)Cl-

(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OR)₂}Ph₂)][SbF₆] (3a,b) and

[Ru(η³:η³-C₁₀H₁₆)Cl(κ²-P,O-Ph₂PCH₂P{dNP(dO)(OR)₂}-

Ph₂)][SbF₆] (7a,b); (c) κ²-P,N-, i.e., [Ru(η⁶-p-cymene)Cl-

(46) We note that TOF₅₀values for complexes 2-5a,b (10-50 h^-1) are

comparable to those found in the related complexes [Ru(η⁶-p-cymene)-

Cl₂{κ¹-P-Ph₂PCH₂P(dN-p-C₅F₄N)Ph₂}] and [Ru(η⁶-p-cymene)Cl{κ²-

P,N-Ph₂PCH₂P(dN-p-C₅F₄N)Ph₂}][SbF₆] (23 and 20 h^-1, respectively,

under the same reaction conditions). See ref 5b.

Acknowledgment. This work was supported by the

Ministerio de Ciencia y Tecnolog´ıa (MCyT) of Spain

(Projects BQU2000-0219, BQU2000-0227, BQU2001-1625

and CAJAL-01-03) and the Gobierno del Principado de

Asturias (Project PR-01-GE-6). We thank the Servei Central

d’Instrumentacio´ Cient´ıfica (SCIC) of the Universitat Jaume

I (Castello´, Spain) for providing us with X-ray facilities as

well as to Dr. Marta Mart´ın (Universidad de Zaragoza) for

EA measurements. S.E.G.-G. also thanks the MCyT for the

award of a Ph.D. grant.

(47) Although no detailed mechanistic studies have been performed, we

assume that the catalytic transformation follows the classical pathway

in which cyclohexanone coordinates on hydride-ruthenium intermedi-

ates (see refs 5b and 45). In fact, ³¹P{¹H} NMR spectra of the catalytic

reaction mixture derived from 7a showed, after 30 min, the clean

2

formation of a novel species with resonances at 4.25 (d, J_PP) 28.3

2

Hz, (EtO)₂PdO), 14.89 (d, J_PP) 28.3 Hz, Ph₂PdN), and 20.51 (s,

Ph₂P) ppm. These chemical shifts and coupling constants show the

κ²-P,O-coordination mode of the ligand arising probably from the

hydride derivative [Ru(η³:η³-C₁₀H₁₆)H(κ²-P,O-Ph₂PCH₂P{dNP(dO)-

(OEt)₂}Ph₂)][SbF₆]. Attempts to isolate this complex failed.

Supporting Information Available: X-ray crystallographic

files, in CIF format, for the structure determinations of complexes

2b, 3b, 7a, and 12b. This material is available free of charge via

the Internet at http://pubs.acs.org.

(48) These derivatives, which are among the most active for transfer

hydrogenation of carbonyl compounds, are the only examples reported

in the literature of ruthenium catalysts containing tridentate P,N,O-

ligands: (a) Yang, H.; Alvarez, M.; Lugan, N.; Mathieu, R. J. Chem.

Soc., Chem. Commun. 1995, 1721. (b) Yang, H.; Alvarez-Gressier,

M.; Lugan, N.; Mathieu, R. Organometallics 1997, 16, 1401.

IC020702K

Inorganic Chemistry, Vol. 42, No. 10, 2003 3307

Article Doi

Ruthenium(II) and ruthenium(IV) complexes containing κ1-P-, κ2-P,O-, and κ3-P,N,O-iminophosphorane-phosphine ligands Ph2PCH2P{=NP(=O)(OR)2}Ph2 (R = Et, Ph): Synthesis, reactivity, theoretical studies, and catalytic activity in transfer hydrogenation of cyclohexanone

DOI: 10.1021/ic020702k

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