Y. Han et al. / Journal of Organometallic Chemistry 693 (2008) 3159–3165
3165
C, 62.09; H, 4.11; N, 4.39. Found: C, 61.79; H, 4.11; N, 4.37%. MS
223(2) K using graphite monochromated Mo
K
a
radiation
(ESI): m/z = 1009 [2MꢀAgBr2]+, 267 [AgBr2]ꢀ.
(k = 0.71073 Å). Data were collected over the full sphere and were
corrected for absorption. Structure solutions were found by the
Patterson method. Structure refinement was carried out by full-
matrix least squares on F2 using SHELXL-97 [13] with first isotropic
and later anisotropic displacement parameters for all non-hydro-
gen atoms. A summary of the most important crystallographic data
is given in Table 1.
4.4. Synthesis of trans-dibromo(1,3-dibenzhydrylbenzimidazolin-2-
ylidene)(acetonitrile)palladium(II) (3)
A mixture of Ag2O (23 mg, 0.1 mmol) and salt A (106 mg,
0.2 mmol) was suspended in CH2Cl2 (10 ml) and stirred at ambient
temperature for 7 h shielded from light. The resulting mixture was
directly filtered into a solution of [PdBr2(CH3CN)2], which in turn
was prepared in situ by heating PdBr2 (53 mg, 0.2 mmol) in CH3CN
(20 ml) under reflux conditions for 6 h. The reaction mixture was
stirred at ambient temperature for 24 h and gradually lightened
up from initially red to yellow. The resulting suspension was fil-
tered through a sintered funnel and the residue was washed by
CH3CN repeatedly until the filtrate is colorless. The solvent of the
filtrate was removed under vacuum to give an orange residue.
Washing the residue with small portions of ice-cold CH3CN fol-
lowed by drying in vacuo afforded the pure product as a yellow
powder (82 mg, 0.11 mmol, 54%). 1H NMR (500 MHz, CD3CN): d
8.54 (s, 2 H, CH), 7.43–7.35 (m, 20 H, Ar-H), 6.91 (m, 2 H, Ar-H),
6.83 (m, 2 H, Ar-H), 1.96 (s, CH3CN, correct integration is not pos-
sible due to ligand exchange with the solvent). 13C{1H} NMR
(125.76 MHz, CD3CN): 165.7 (s, Ccarbene), 138.2, 135.1, 130.0,
129.4, 129.2, 124.0 (s, Ar-C), 118.3 (s, CN), 114.8 (s, Ar-C), 69.2 (s,
CH), 1.32 (m, CH3CN, assignment is tentative due to overlap with
solvent signals). Anal. Calc. for C35H29Br2N3Pd: C, 55.47; H, 3.86;
N, 5.54. Found: C, 55.81; H, 4.26; N, 5.39%. MS (ESI): m/z = 678
[MꢀBr]+, 1353 [2Mꢀ2CH3CNꢀBr]+.
Acknowledgements
We thank the National University of Singapore for financial sup-
port (Grant No. R 143-000-268-112) and the CMMAC staff of our
department for technical assistance.
Appendix A. Supplementary material
CCDC 686371, 686372, 686373 and 686374 contains the sup-
plementary crystallographic data for (1), (2), (3) and (4). These data
can be obtained free of charge from The Cambridge Crystallo-
Supplementary data associated with this article can be found, in
References
[1] (a) F.E. Hahn, Angew. Chem., Int. Ed. 45 (2006) 1348;
(b) W.A. Herrmann, Angew. Chem., Int. Ed. 41 (2002) 1290;
(c) V. César, S. Bellemin-Laponnaz, L.H. Gade, Chem. Soc. Rev. 33 (2004) 619;
(d) E. Peris, R.H. Crabtree, Coord. Chem. Rev. 248 (2004) 2239;
(e) D. Bourissou, O. Guerret, F.P. Gabbaï, G. Bertrand, Chem. Rev. 100 (2000)
39;
(f) F.E. Hahn, M.C. Jahnke, Angew. Chem., Int. Ed. 47 (2008) 3122.
[2] E.A.B. Kantchev, C.J. O’Brien, M.G. Organ, Angew. Chem., Int. Ed. 46 (2007) 2768
and references therein.
4.5. Synthesis of di-l-bromobis(1,3-dibenzhydrylbenzimidazolin-2-
ylidene)dibromodipalladium(II) (4)
Complex 3 (76 mg, 0.1 mmol) was suspended in Et2O (20 ml)
and stirred at ambient temperature overnight. The resulting mix-
ture was filtered through a sintered funnel and the residue was
washed by Et2O again (10 ml ꢂ 3). Drying the residue in vacuo
afforded the product as an orange powder (71 mg, 0.049 mmol,
99%). 1H NMR (500 MHz, CDCl3): d 8.76 (s, 4 H, CH), 7.44–7.31
(m, 40 H, Ar-H), 6.88 (m, 4 H, Ar-H), 6.82 (m, 4 H, Ar-H). 13C{1H}
NMR (125.76 MHz, CDCl3): 165.2 (s, Ccarbene), 137.5, 135.1, 129.8,
129.4, 129.0, 123.6, 114.5 (s, Ar-C), 69.4 (s, CH). Anal. Calc. for
[3] (a) F.E. Hahn, L. Wittenbecher, D. Le Van, R. Fröhlich, Angew. Chem., Int. Ed. 39
(2000) 541;
(b) F.E. Hahn, L. Wittenbecher, R. Boese, D. Bläser, Chem. Eur. J. 5 (1999) 1931.
[4] (a) H.V. Huynh, Y. Han, J.H.H. Ho, G.K. Tan, Organometallics 25 (2006) 3267;
(b) Y. Han, H.V. Huynh, L.L. Koh, J. Organomet. Chem. 692 (2007) 3606;
(c) H.V. Huynh, J.H.H. Ho, T.C. Neo, L.L. Koh, J. Organomet. Chem. 690 (2005)
3854;
(d) H.V. Huynh, T.C. Neo, G.K. Tan, Organometallics 25 (2006) 1298;
(e) H.V. Huynh, C. Holtgrewe, T. Pape, L.L. Koh, F.E. Hahn, Organometallics 25
(2006) 245;
(f) Y. Han, H.V. Huynh, G.K. Tan, Organometallics 26 (2007) 4612;
(g) Y. Han, H.V. Huynh, G.K. Tan, Organometallics 26 (2007) 6447;
(h) H.V. Huynh, R. Jothibasu, L.L. Koh, Organometallics 26 (2007) 6852.
[5] (a) F.E. Hahn, M. Foth, J. Organomet. Chem. 585 (1999) 241;
(b) F.E. Hahn, M.C. Jahnke, V. Gomez-Benitez, D. Morales-Morales, T. Pape,
Organometallics 24 (2005) 6458;
C66H52Br4N4Pd2: C, 55.29; H, 3.66; N, 3.91. Found: C, 55.00; H,
3.73; N, 3.81%. MS (ESI): m/z = 1353 [MꢀBr].
4.6. General procedure for the Suzuki–Miyaura cross-coupling reaction
(c) F.E. Hahn, C. Holtgrewe, T. Pape, Z. Naturforsch. 59b (2004) 1051.
[6] (a) S. Burling, M.F. Mahon, R.E. Powell, M.K. Whittlesey, J.M.J. Williams, J. Am.
Chem. Soc. 128 (2006) 13702;
In a typical run, a Schlenk-tube was charged with a mixture of
aryl halide (1.0 mmol), phenylboronic acid (1.2 mmol), potassium
carbonate (1.5 mmol), precatalyst (0.005 mmol) and [N(n-
C4H9)4]Br (1.5 mmol) (for entries 11–14 in Table 3). The reaction
vessel was degassed under vacuum and filled with nitrogen. The
solvent (3 ml) was then added to the mixture using a syringe.
The reaction mixture was vigorously stirred at the appropriate
temperature. After the desired reaction time, the solution was al-
lowed to cool and quenched by adding 5 ml of aqueous HCl solu-
tion (2.4 M). Dichloromethane (10 ml) was added to the reaction
mixture and the organic phase was extracted with water
(6 ꢂ 5 ml) and dried over MgSO4. The solvent was removed by
evaporation to give a crude product, which was analyzed by 1H
NMR spectroscopy.
(b) H.V. Huynh, N. Meier, T. Pape, F.E. Hahn, Organometallics 25 (2006) 3012;
(c) S.K. Yen, L.L. Koh, H.V. Huynh, T.S.A. Hor, Dalton Trans. (2007) 3952;
(d) C. Holtgrewe, C. Diedrich, T. Pape, S. Grimme, F.E. Hahn, Eur. J. Org. Chem.
(2006) 3116;
(e) B. Çetinkaya, E. Çetinkaya, J.A. Chamizo, P.B. Hitchcock, H.A. Jasim, H.
Küçükbay, M.F. Lappert, J. Chem. Soc., Perkin Trans. 1 (1998) 2047.
[7] H.M.J. Wang, I.J.B. Lin, Organometallics 17 (1998) 972.
[8] (a) C.K. Lee, C.S. Vasam, T.W. Huang, H.M.J. Wang, R.Y. Yang, C.S. Lee, I.J.B. Lin,
Organometallics 25 (2006) 3768;
(b) L. Ray, V. Katiyar, S. Barman, M.J. Raihan, H. Nanavati, M.M.P. Shaikh, J.
Organomet. Chem. 692 (2007) 4259;
(c) W. Huang, R. Zhang, G. Zou, J. Tang, J. Sun, J. Organomet. Chem. 692 (2007)
3804;
(d) Q.-X. Liu, L.-N. Yin, J.-C. Feng, J. Organomet. Chem. 692 (2007) 3655.
[9] (a) I.J.B. Lin, C.S. Vasam, Comment. Inorg. Chem. 25 (2004) 75;
(b) I.J.B. Lin, C.S. Vasam, Coord. Chem. Rev. 251 (2007) 642;
(c) J.C. Garrison, W.J. Youngs, Chem. Rev. 105 (2005) 3978.
[10] (a) R.B. Bedford, M.E. Blake, C.P. Butts, D. Holder, Chem. Commun. (2003) 466;
(b) M.T. Reetz, E. Westermann, Angew. Chem., Int. Ed. 39 (2000) 165.
[11] J.G. de Vries, Dalton Trans. (2006) 421.
4.7. X-Ray diffraction studies
[12] H.V. Huynh, L.R. Wong, P.S. Ng, Organometallics 27 (2008) 2231.
[13] G.M. Sheldrick, SHELXL-97, Universität Göttingen, Germany, 1997.
Diffraction data for complexes 1–4 were collected with a Bruker
AXS APEX CCD diffractometer equipped with a rotation anode at