4228
J. Am. Chem. Soc. 1998, 120, 4228-4229
Scheme 1. New Orthometalated Ruthenium Complexes
Exchange Couplings between a Hydride and a
Stretched Dihydrogen Ligand in Ruthenium
Complexes
Yannick Guari, Sylviane Sabo-Etienne, and Bruno Chaudret*
Laboratoire de Chimie de Coordination CNRS
205 route de Narbonne, 31077 Toulouse Cedex, France
ReceiVed May 19, 1997
Over 10 years after the Kubas discovery, the chemistry of
dihydrogen has proven to be far more complex than originally
thought. Thus coordinated dihydrogen can be unstretched,
stretched, electrophilic, or even superacidic.1 The study of the
reactivity of stretched dihydrogen derivatives, which are known
in particular in the chemistry of rhenium, ruthenium, and osmium,
has remained relatively unexplored.1c,2 We have studied for a
few years the reactivity of ruthenium dihydrogen complexes and
have demonstrated that, whereas dihydrogen substitution and
hydrogen transfer is easy on RuH2(H2)2(PCy3)2 (1),3 the related
complexes RuH(H2)(LX)(PCy3)2 (LX ) o-OC5H4N, pyO, 2; LX
) o-NHC5H4N, pyNH, 3) which accommodate a stretched
dihydrogen ligand are found to be much less reactive.4 In
addition, stretched dihydrogen ligands may experience a high
ing H2 by CO in 5 leads to RuH(CO)(ph-py)(PiPr3)2 (6). Full
characterization of the complexes is given in the Supporting
Information. The similarity of 31P and 13C NMR data (triplets
for metalated carbon respectively at 197.0 ppm, JP-C ) 10.6 Hz
and 192.0 ppm, JP-C ) 13.1 Hz) demonstrates that 5 and 6 are
1
isostructural. The only difference is their high-field H NMR
spectra: broad triplet at -8.59 ppm for 5 (JP-H ) 12.3 Hz, 3 H;
T1 min ) 22 ms at 258 K, 400 MHz, C7D8) and sharp triplet at
-12.50 ppm (JP-H ) 24.6 Hz, 1 H; T1 min ) 202 ms at 233 K,
250 MHz, C7D8) for 6. The calculation of the H-H bond length
in 5, using 6 as a reference for all effects other than H-H
distance,12 gives a value of 1.08 Å (slow rotation hypothesis, 0.83
Å for rapid rotation hypothesis), close to that found by X-ray
5
rotation barrier that we have demonstrated, at least in the case
of tantalum 6 and niobium,7 to be related to the existence of large
quantum mechanical exchange couplings.6,8,9
Exchange couplings have been previously observed in di- and
trihydride complexes8,9 and in tantalum6 and niobium7 dihydrogen
complexes. We now report the synthesis of a series of hydrido
orthometalated dihydrogen complexes showing exchange cou-
plings as well as preliminary catalytic activity for the coupling
of ethylene to functional arenes (Murai’s reaction).10
Phenylpyridine reacts rapidly at room temperature in pentane
with 1 to yield the new compound RuH(H2)(Ph-py)(PCy3)2
(Ph-py ) o-C6H4C5H4N, 4) as a slightly soluble orange powder
(see Scheme 1). The analogous and more soluble triisopropyl-
phosphine derivative RuH(H2)(Ph-py)(PiPr3)2 (5) could be pre-
pared directly from Ru(COD)(COT) (COD ) 1,5 cyclooctadiene,
COT ) 1,3,5-cyclooctatriene), PiPr3, and dihydrogen.11 Substitut-
i
and NMR for RuHI(H2)(PR3)2 (R ) Cy, Pr), 1.03 Å,11,13 and
much less than that found for 2 and 3, ca.1.3 Å.4 In the 1H NMR
spectra of 4 and 5 we observe at low temperature the decoales-
cence of the high-field signal into an AB2 spin system at -12.1
and -6.1 ppm (∆Gq 39.8 kJ mol-1) displaying quantum mechan-
ical exchange couplings clearly visible for 5 between 218 K
(JHA-HB ) 308 Hz) and 188 K (JHA-HB ) 141 Hz; see Figure 1).
After the decoalescence, the relaxation time of HA is always
observed to be longer than that of HB (198 K: HB δ-6.1, 69 ms;
HA δ-12.1, 87 ms; 208 K: HB δ-6.2, 34 ms; HA δ-12.2, 38 ms) but
both signals remain in exchange as evidenced by T1 averaging.14
4 displays similar features, but they are more difficult to observe
because of low solubility and the large correlation time of PCy3
complexes. As stated above, complexes 5 and 6 display very
(1) (a) Kubas, G. J. Acc. Chem. Res. 1988, 21, 120. (b) Crabtree, R. H.
Acc. Chem. Res. 1990, 23, 95. (c) Crabtree, R. H. Angew. Chem., Int. Ed.
Engl. 1993, 32, 2, 789. (d) Jessop, P. G.; Morris, R. H. Coord. Chem. ReV.
1992, 121, 155. (e) Heinekey, D. M.; Oldham, W. J., Jr. Chem. ReV. 1993,
93, 913.
(8) Some leading references on exchange couplings (complexes, NMR
origin, and quantum mechanical calculations): (a) Arliguie, T.; Chaudret, B.;
Devillers, J.; Poilblanc, R. C. R. Hebd. Seances Acad. Sci., Ser. 2 1987, 305,
1523. (b) Zilm, K. W.; Heinekey, D. M.; Millar, J. M.; Payne, N. G.; Neshyba,
S. P.; Duchamp, J. C.; Szcyrba, J. J. Am. Chem. Soc. 1990, 112, 920. (c)
Heinekey, D. M. J. Am. Chem. Soc. 1991, 113, 6074. (d) Jones, D. H.;
Labinger, J. A.; Weitekamp, D. P. J. Am. Chem. Soc. 1989, 11, 3087. (e)
Limbach, H.-H.; Scherer, G.; Maurer, M.; Chaudret, B. Angew. Chem., Int.
Ed. Engl. 1992, 31, 1369. (f) Barthelat, J. C.; Chaudret, B.; Daudey, J. P.; De
Loth, P.; Poilblanc, R. J. Am. Chem. Soc. 1991, 113, 9896. (g) Gusev, D. G.;
Kuhlman, R.; Sini, G.; Eisenstein, O.; Caulton, K. G. J. Am. Chem. Soc. 1994,
116, 2685. (h) Clot, E.; Leforestier, C.; Eisenstein, O.; Pe´lissier, M. J. Am.
Chem. Soc. 1995, 117, 1797. (i) Jarid, A.; Moreno, M.; Lledos, A.; Lluch, J.
M.; Bertran, J. J. Am. Chem. Soc. 1995, 117, 1069.
(2) (a) Earl, K. A.; Jia, G.; Maltby, P. A.; Morris, R. H. J. Am. Chem. Soc.
1991, 113, 3027. (b) Brammer, L.; Howard, J. A. K.; Johnson, O.; Koetzle,
T. F.; Spencer, J. L.; Stringer, A. M. J. Chem. Soc., Chem. Commun. 1991,
241. (c) Albinati, A.; Bakhmutov, V. I.; Caulton, K. G.; Clot, E.; Eckert, J.;
Eisenstein, O.; Gusev, D. G.; Grushin, V. V.; Hauger, B. E.; Klooster, W. T.;
Koetzle, T. F.; McMullan, R. K.; O’Loughlin, T. J.; Pelissier, M.; Ricci, J.
S.; Sigalas, M. P.; Vymenits, A. B. J. Am. Chem. Soc. 1993, 115, 7300. (d)
Johnson, T. J.; Albinati, A.; Koetzle, T. F.; Ricci, J.; Eisenstein, O.; Huffman,
J. C.; Caulton, K. G. Inorg. Chem. 1994, 33, 4966. (e) Hasegawa, T.; Li, Z.;
Parkin, S.; Hope, H.; McMullan, R. K.; Koetzle, T. F.; Taube, H. J. Am. Chem.
Soc. 1994, 116, 4352.
(3) (a) Christ, M. L.; Sabo-Etienne, S.; Chaudret, B. Organometallics 1994,
13, 3800. (b) Christ, M. L.; Sabo-Etienne, S.; Chaudret, B. Organometallics
1995, 14, 1082. (c) Borowski A.; Sabo-Etienne, S.; Christ, M. L.; Donnadieu
B.; Chaudret, B. Organometallics 1996, 15, 1427. (d) Delpech, F.; Sabo-
Etienne, S.; Chaudret, B.; Daran, J.-C. J. Am. Chem. Soc. 1997, 119, 3167.
(e) Sabo-Etienne S.; Chaudret B. Coord. Chem. ReV., in press.
(4) Guari, Y.; Sabo-Etienne, S.; Chaudret, B. Organometallics 1996, 15,
3471.
(9) Sabo-Etienne S.; Chaudret B. Chem. ReV., submitted.
(10) (a) Murai, S.; Kakiuchi, F.; Sekine, S.; Tanaka, Y.; Kamatani, A.;
Sonoda, M.; Chatani, N. Nature, 1993, 366, 529. (b) Kakiuchi, F.; Sekine,
S.; Tanaka, Y.; Kamatani, A.; Sonoda, M.; Chatani, N.; Murai, S. Bull. Chem.
Soc. Jpn. 1995, 68, 62, (c) Sonoda M.; Kakiuchi F.; Kamatani A.; Chatani
N.; Murai S. Chem. Lett. 1996, 113 and references therein.
(11) Burrow, T.; Sabo-Etienne, S.; Chaudret, B. Inorg. Chem. 1995, 34,
2470.
(5) Klooster, W. T.; Koetzle, T. F.; Jia, G.; Fong, T. P.; Morris, R. H.;
Albinati, A. J. Am. Chem. Soc. 1994, 116, 7677.
(12) (a) Desrosiers, P. J.; Cai, P.; Lin, Z.; Richards, R.; Halpern, J. J. Am.
Chem. Soc. 1991, 113, 4173. (b) Bautista, M. T.; Capellani, E. P.; Drouin, S.
D.; Morris, R. H.; Schweitzer, C. T.; Sella, A.; Zubkowski, J. P. J. Am. Chem.
Soc. 1991, 113, 4876. (c) Moreno, B.; Sabo-Etienne, S.; Chaudret, B.;
Rodriguez, A.; Jalon, F.; Trofimenko, S. J. Am. Chem. Soc. 1995, 117, 7441.
(13) Chaudret, B. Chung, G.; Eisenstein, O.; Jackson, S. A.; Lahoz, F.;
Lopez, J. A. J. Am. Chem. Soc. 1991, 113, 2314.
(6) Sabo-Etienne, S.; Chaudret, B.; Abou el Makarim, H.; Barthelat, J.-C.;
Daudey, J.-P.; Ulrich, S.; Limbach, H.-H.; Moise, C. J. Am. Chem. Soc. 1995,
117, 11602.
(7) Jalon, F. A.; Manzano, B.; Otero, A.; Villasenor, E.; Chaudret, B. J.
Am. Chem. Soc. 1995, 117, 10123.
S0002-7863(97)01603-X CCC: $15.00 © 1998 American Chemical Society
Published on Web 04/16/1998