We thank the Swiss National Science Foundation, Univer-
sity College Dublin, and the Italian MIUR (PRIN N1
207HMTJWP_002) for financial support. Tiziano Montini
(Department of Chemical and Pharmaceutical Sciences,
University of Trieste) is acknowledged for the GC-MS analysis.
Fondazione CRTrieste is gratefully acknowledged for the generous
donation of a Varian 500 MHz spectrometer to the Dipartimento
di Scienze Chimiche e Farmaceutiche, and the Fondazione Benefica
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‘‘Kathleen Foreman Casali’’ for the generous donation of the Buchi
¨
tinyclave steel reactor.
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Experimental section
The imidazolium salt 1 (0.060 g, 0.17 mmol) was refluxed with
Ag2CO3 (0.036 g, 0.13 mmol) in CH2Cl2 (5 ml) for 15 h and
then filtered through a short pad of Celite, affording a solution
of carbene silver complex.
Separately, AgBF4 (0.039 g, 0.20 mmol) was added to a
solution of [PdCl(Me)(cod)] (0.046 g, 0.17 mmol) in MeCN
(2 ml). After stirring for 15 h, the mixture was filtered over
Celite. The solution of carbene silver complex was added
dropwise to this filtrate and the reaction mixture was stirred
at room temperature for 4 h under exclusion of light. After
filtration through Celite, all volatiles were removed under
reduced pressure. The resulting brown oil was dissolved in
CH2Cl2 (5 ml) and the solution was stirred over activated
carbon for 30 min. and filtered again through Celite. The filtrate
was concentrated in vacuo and the residue was recrystallized
from MeCN–Et2O to give an off-white solid (0.016 g, 18%).
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16 All bond lengths are very similar, the largest difference pertains to
the Pd–N3 bond length, which is slightly shorter in 2 and which
translates into a slightly larger ligand bite angle than in the mesityl
analogue. Even though the metric differences are small, they
appear to reflect intramolecular repulsion induced by the bulky
mesityl and xylyl groups.
17 This distortion has been defined as the angle of the
C(pyridyl)–C(xylyl) bond with the least square plane of the palladium
coordination sphere, i.e. Pd, C1, C18, N3, and N4. The mesityl
analogue C1 shows a similar distortion (18.81).
Notes and references
z Crystal data for 2: C20H23BF4N4Pd, M = 512.63, monoclinic, space
group P21/c (No. 14), a = 6.98977(7) A, b = 20.8653(2) A,
bc = 14.1374(1) A, b = 92.862(1)1, U = 2059.28(3) A3, T = 100(2)K,
Z = 4, 46383 total reflections, 5371 unique (Rint = 0.0307), R1 = 0.0209,
wR2 = 0.0484, for I 4 2s(I), CCDC no. 872297.
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c
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