Communication
ChemComm
Fig. 3 The calculated energy diagram of p-bromotoluene at each step along the proposed reaction mechanism.
Notes and references
1 K. An and G. A. Somorjai, ChemCatChem, 2012, 4, 1512.
on Pd(110), Pd(100), and Pd(111), respectively (Fig. 3 and Table S1,
ESI†). Since the amine molecules in the reaction solution might
re-occupy the binding sites immediately after the dissociation of the
product due to their dominant concentration, the energy value was
taken as the sum of the reductive elimination energy of the aryl–
amide intermediate and the Eads of the amine. The negative energy
values indicate that the reductive elimination step is favorable
for all the three different facets. We believe that the oxidative
addition step should be more important in determining the
overall reaction rate than the other steps because once the
addition occurred against the competitive binding of amines
2 Y. Xia, Y. Xiong, B. Lim and S. E. Skrabalak, Angew. Chem., Int. Ed.,
2009, 48, 60.
3 A. R. Tao, S. Habas and P. Yang, Small, 2008, 4, 310.
4 K. Zhou and Y. Li, Angew. Chem., Int. Ed., 2012, 51, 602.
5 J. W. Hong, M. Kim, Y. Kim and S. W. Han, Chem. – Eur. J., 2012, 18, 16626.
6 C.-W. Yang, K. Chanda, P.-H. Lin, Y.-N. Wang, C.-W. Liao and M. H.
Huang, J. Am. Chem. Soc., 2011, 133, 19993.
7 C.-Y. Chiu, P.-J. Chung, K.-U. Lao, C.-W. Liao and M. H. Huang,
J. Phys. Chem. C, 2012, 116, 23757.
8 Y. Wu, S. Cai, D. Wang, W. He and Y. Li, J. Am. Chem. Soc., 2012, 134, 8975.
9 F. Wang, C. Li, L.-D. Sun, H. Wu, T. Ming, J. Wang, J. C. Yu and C.-H.
Yan, J. Am. Chem. Soc., 2010, 133, 1106.
on the surface, the diffusion of Br and the elimination of 10 R. Narayanan and M. A. El-Sayed, Nano Lett., 2004, 4, 1343.
11 M. Crespo-Quesada, A. Yarulin, M. Jin, Y. Xia and L. Kiwi-Minsker,
products readily followed. Taken together, the DFT calculations
J. Am. Chem. Soc., 2011, 133, 12787.
show that the finely tuned surface of Pd NCs not only enhances
12 M. M. Telkar, C. V. Rode, R. V. Chaudhari, S. S. Joshi and A. M. Nalawade,
the oxidative addition of aryl bromide, but also makes the
cleavage of Br atoms and the elimination of products easier.
The different facets of NCs distinctively play a pivotal role in
Appl. Catal., A, 2004, 273, 11.
13 B. Lim, M. Jiang, J. Tao, P. H. C. Camargo, Y. Zhu and Y. Xia,
Adv. Funct. Mater., 2009, 19, 189.
14 W. Niu, L. Zhang and G. Xu, ACS Nano, 2010, 4, 1987.
each step due to their unique properties. These results clearly 15 J. W. Hong, S. W. Kang, B.-S. Choi, D. Kim, S. B. Lee and S. W. Han,
ACS Nano, 2012, 6, 2410.
16 Y. W. Lee, D. Kim, J. W. Hong, S. W. Kang, S. B. Lee and S. W. Han,
explain the experimental trend in the reactivity of Pd NCs.
In summary, through a comparative study of heterogeneous
Small, 2013, 9, 646.
Buchwald–Hartwig amination using the shape-controlled Pd 17 W. Cabri and I. Candiani, Acc. Chem. Res., 1995, 28, 2.
18 N. Miyaura and A. Suzuki, Chem. Rev., 1995, 95, 2457.
19 J. K. Stille, Angew. Chem., Int. Ed., 1986, 25, 508.
20 Y. Hatanaka and T. Hiyama, J. Org. Chem., 1988, 53, 918.
NCs, we found strong facet-dependence of catalytic reactivity.
Further investigations showed that the contribution of leached
Pd is negligible, indicating that the reaction propagates directly 21 K. Sonogashira, Y. Tohda and N. Hagihara, Tetrahedron Lett., 1975,
16, 4467.
on the surface of the finely-tuned Pd NCs. Theoretical investiga-
tions unequivocally revealed that the oxidative addition of aryl
22 E. Negishi, Acc. Chem. Res., 1982, 15, 340.
23 J. P. Wolfe, S. Wagaw, J.-F. Marcoux and S. L. Buchwald, Acc. Chem.
bromide to the metal surface with a well-defined facet, regarded
as the rate-determining step, is favored in the order of Pd(110),
Pd(100), and Pd(111), which could explain their relative catalytic
Res., 1998, 31, 805.
24 J. F. Hartwig, Acc. Chem. Res., 2008, 41, 1534.
25 M. M. Blake, S. U. Nanayakkara, S. A. Claridge, L. C. Fernandez-Torres,
´
E. C. H. Sykes and P. S. Weiss, J. Phys. Chem. A, 2009, 113, 13167.
¨
¨
reactivities observed in the experiments. These results empha- 26 J. Bjork, F. Hanke and S. Stafstrom, J. Am. Chem. Soc., 2013, 135, 5768.
size that controlling the morphology of metal NCs is explicitly a
key step toward the rational design of heterogeneous catalysts.
27 L. Grill, M. Dyer, L. Lafferentz, M. Persson, M. V. Peters and S. Hecht,
Nat. Nanotechnol., 2007, 2, 687.
28 D. F. Perepichka and F. Rosei, Science, 2009, 323, 216.
This work was supported by Basic Science Research Programs 29 Y.-H. Chen, H.-H. Hung and M. H. Huang, J. Am. Chem. Soc., 2009, 131, 9114.
30 F. Wang, C. Li, L.-D. Sun, C.-H. Xu, J. Wang, J. C. Yu and C.-H. Yan,
Angew. Chem., Int. Ed., 2012, 51, 4872.
31 J. A. Widegren and R. G. Finke, J. Mol. Catal. A: Chem., 2003, 198, 317.
(2010-0029149, 2012R1A1A1004154), EPB Center (2008-0061892),
and MIR Center (2009-0083525) through the NRF funded by the
Korea government (MSIP), and was also supported by Institute for 32 N. T. S. Phan, M. Van Der Sluys and C. W. Jones, Adv. Synth. Catal.,
2006, 348, 609.
Basic Science (IBS) [CA1301] and KAIST High Risk High Return
Project (HRHRP). W. Y. K. is also grateful for financial support
33 G. Kresse and J. Furthmu¨ller, Phys. Rev. B: Condens. Matter Mater.
Phys., 1996, 54, 11169.
from a Chung-Am Fellowship.
34 J. P. Perdew, K. Burke and M. Ernzerhof, Phys. Rev. Lett., 1996, 77, 3865.
This journal is ©The Royal Society of Chemistry 2014
Chem. Commun., 2014, 50, 9454--9457 | 9457