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Notes and references
‡ NMR data for [IrH2(POCOP)] (1) (C6D6): 31P NMR: d 204.9 (s); 1H NMR:
d –17.0 (t, Ir–H). [IrHCl(POCOP)] (3) (CD2Cl2): 31P NMR: d 175.8 (s);
1H NMR: d –41.4 (t, Ir–H) (see ESI†).
1 Z. Xu, F. S. Xiao, S. K. Purnell, O. Alexeev, S. Kawi, S. E. Deutsch and
B. C. Gates, Nature, 1994, 372, 346–348.
2 (a) G. Kyriakou, M. B. Boucher, A. D. Jewell, E. A. Lewis, T. J. Lawton,
A. E. Baber, H. L. Tierney, M. Flytzani-Stephanopoulos and E. C. H.
Sykes, Science, 2012, 335, 1209–1212; (b) M. Flytzani-Stephanopoulos
and B. C. Gates, in Annual Review of Chemical and Biomolecular
Engineering, ed. J. M. Prausnitz, Annual Reviews, Palo Alto, 2012,
Vol. 3, pp. 545–574.
3 V. Ortalan, A. Uzun, B. C. Gates and N. D. Browning, Nat. Nano-
technol., 2010, 5, 506–510.
4 Modern Surface Organometallic Chemistry, ed. J.-M. Basset, R. Psaro,
D. Roberto and R. Ugo, Wiley-VCH, Weinheim, 2009.
5 Z. Huang, P. S. White and M. Brookhart, Nature, 2010, 465, 598–601.
Fig. 3 Reaction profile (mole fraction of ethene and ethane as a function of
time) determined by gas-phase NMR spectroscopy.
´
6 (a) C. Coperet, Chem. Rev., 2010, 110, 656–680; (b) C. Coperet,
M. Chabanas, R. Petroff Saint-Arroman and J.-M. Basset, Angew.
Chem., Int. Ed., 2003, 42, 156–181; (c) R. Anwander, Chem. Mater.,
2001, 13, 4419–4438.
after the hydrogenation reaction. Also, catalyst 2 was recovered
under an inert atmosphere and reused three times with essentially
the same results (see ESI†).
´
7 (a) J. Corker, F. Lefebvre, C. Lecuyer, V. Dufaud, F. Quignard,
A. Choplin, J. Evans and J.-M. Basset, Science, 1996, 271, 966–969;
´
(b) V. Vidal, A. Theolier, J. Thivolle-Cazat and J.-M. Basset, Science,
Finally, the catalytic reaction was monitored by 1H NMR
spectroscopy. Solid catalyst 2 was introduced into an NMR tube,
which was then filled with a 1 : 1 mixture of ethene and
hydrogen at room temperature and immediately placed into
the magnet of the NMR spectrometer. The consumption of
´
1997, 276, 99–102; (c) J.-M. Basset, C. Coperet, D. Soulivong,
M. Taoufik and J. T. Cazat, Acc. Chem. Res., 2009, 43, 323–334.
8 (a) T. Maschmeyer, F. Rey, G. Sankar and J. M. Thomas, Nature,
1995, 378, 159–162; (b) R. Buffon and R. Rinaldi, in Modern Surface
Organometallic Chemistry, Wiley-VCH, Weinheim, 2009, pp. 417–453.
9 (a) B. Marciniec, K. Szubert, M. J. Potrzebowski, I. Kownacki and
K. Łe¸szczak, Angew. Chem., Int. Ed., 2008, 47, 541–544; (b) M. D. Ward
and J. Schwartz, J. Am. Chem. Soc., 1981, 103, 5253–5255;
(c) B. Marciniec, S. Rogalski, M. J. Potrzebowski and C. Pietraszuk,
ChemCatChem, 2011, 3, 904–910; (d) M. K. Richmond, S. L. Scott and
H. Alper, J. Am. Chem. Soc., 2001, 123, 10521–10525; (e) S. L. Scott,
M. Szpakowicz, A. Mills and C. C. Santini, J. Am. Chem. Soc., 1998, 120,
1883–1890; ( f ) Y. S. Choi, E. G. Moschetta, J. T. Miller, M. Fasulo,
M. J. McMurdo, R. M. Rioux and T. D. Tilley, ACS Catal., 2011, 1,
1166–1177; (g) D. A. Ruddy, J. Jarupatrakorn, R. M. Rioux, J. T. Miller,
M. J. McMurdo, J. L. McBee, K. A. Tupper and T. D. Tilley, Chem.
Mater., 2008, 20, 6517–6527.
1
ethene and the formation of ethane were followed by H NMR
spectroscopy in the gas phase. The mole fraction calculated
from the normalized intensities is plotted as a function of the
reaction time as shown in Fig. 3. The reaction profile shows
that the catalyst has no induction period. We speculate that the
reaction involves alkene insertion into the Ir–H bond and
protonolysis of the Ir–C bond by heterolytic splitting of H2 to
give the alkane and regenerate 2. The reactions of 2 with liquid
alkenes and with soluble analogues of 2, such as the siloxo
complex 4, will be studied by NMR spectroscopy to gain
mechanistic insight.
10 (a) H. C. Foley, S. J. DeCanio, K. D. Tau, K. J. Chao, J. H. Onuferko,
C. Dybowski and B. C. Gates, J. Am. Chem. Soc., 1983, 105,
3074–3082; (b) J. Lu, C. Aydin, N. D. Browning and B. C. Gates,
J. Am. Chem. Soc., 2012, 134, 5022–5025.
The reaction of a transition metal hydride with silica is a
valuable extension of the grafting strategies that exploit the
reaction of the Si–OH groups of silica with allyl or alkyl
complexes6b or with preformed siloxo complexes.9a, f,g More
importantly, the silica-grafted iridium hydride 2 is, to the best
of our knowledge, an unprecedented example of a fine disper-
sion on the surface of a stable, yet reactive hydride complex of a
late transition metal that has a well defined coordination
environment and resists decomposition to metal nanoparticles.
The robust pincer ligand plays a pivotal role in stabilising the
silica-grafted hydride complex and preventing aggregation. As
hydride pincer complexes of other late transition metals are
known, this methodology should give access to a new class of
catalytically active materials with unexplored potential.
11 R. Berthoud, A. Baudouin, B. Fenet, W. Lukens, K. Pelzer, J.-M. Basset,
´
J.-P. Candy and C. Coperet, Chem.–Eur. J., 2008, 14, 3523–3526.
12 (a) C. Nedez, A. Choplin, F. Lefebvre, J. M. Basset and E. Benazzi,
Inorg. Chem., 1994, 33, 1099–1102; (b) C. Nedez, A. Theolier,
F. Lefebvre, A. Choplin, J. M. Basset and J. F. Joly, J. Am. Chem.
Soc., 1993, 115, 722–729.
13 D. Zhao, J. Feng, Q. Huo, N. Melosh, G. H. Fredrickson,
B. F. Chmelka and G. D. Stucky, Science, 1998, 279, 548–552.
14 I. Gottker-Schnetmann, P. White and M. Brookhart, J. Am. Chem.
Soc., 2004, 126, 1804–1811.
15 A. C. Sykes, P. White and M. Brookhart, Organometallics, 2006, 25,
1664–1675.
16 (a) A. Arunachalampillai, D. Olsson and O. F. Wendt, Dalton Trans., 2009,
8626–8630; (b) I. Kownacki, M. Kubicki, K. Szubert and B. Marciniec,
J. Organomet. Chem., 2008, 693, 321–328, and references therein.
17 (a) H. Schmidbaur and J. Adlkofer, Chem. Ber., 1974, 107, 3680–3683;
(b) I. Kownacki, B. Marciniec and M. Kubicki, Chem. Commun., 2003,
76–77.
c
11316 Chem. Commun., 2013, 49, 11314--11316
This journal is The Royal Society of Chemistry 2013