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ic data for this paper. These data are provided free of charge by
phere at room temperature; however, in solution the clusters
decompose quickly, as evidenced by the formation of a black-
colored suspension in the reaction solution. Although crystals
1
of 6 are unstable in solution, H and 13C{1H} NMR spectra can
UV/Vis diffuse reflectance spectra of the solid samples were record-
ed using a Shimadzu UV-VIS-NIR spectrophotometer UV-3600 with
an integrating sphere attachment ISR-3100. Barium sulfate was
used as reflectance standard and as the diluting matrix for the
finely ground samples (5–10% in mixture). Spectra were converted
using the Kubelka-Munk function and normalized. Solid-state PL
spectra were obtained at room temperature using the experimen-
tal setup shown in the Supporting Information, Figure S4. An exci-
tation beam from laser diode (US-Lasers, Inc.) with wavelength
405Æ10 nm and power output of 120 mW was filtered using
a low-pass (405 nm) filter. The emitted fluorescence was filtered
using a long-pass filter and analyzed using a HRS-BD1 Mightex
Spectrometer equipped with CCD multichannel detector with en-
trance slit size 10 mm and wavelength range 300–1050 nm. Calibra-
tion and data processing were performed with custom-made code
using Matlab (version 2014) software. To prepare samples for solid
state PL measurements, a small amount of solid material was sus-
pended in 1–2 mL of pentane. One drop of such a suspension was
placed on a cleaned Si wafer and allowed to evaporate; procedure
was repeated until desired density of coverage was achieved, and
then the substrate with a thin film of a sample was thoroughly
dried, finally under vacuum.
be obtained by dissolving the crystals in cold CDCl3 (À308C;
NMR spectra of 6 display only one set of resonances for the li-
gated carbenes.
Conclusion
Exploiting the stabilizing effect of ligated N-heterocyclic car-
benes to metal–chalcogenolate MÀESiMe3 moieties, we have
isolated [(IPr)AgÀESiMe3] and [(iPr2-bimy)CuÀESiMe3]2 (E=S, Se)
complexes. The reaction of [(IPr)AgÀSSiMe3] with mercuric(II)
acetate afforded the heterometallic complex [{(IPr)AgS}2Hg],
which is the first example of a mixed silver–mercury–sulfide
complex. The smaller NHC iPr2-bimy provides decent stability
for CuÀSSiMe3, although [(iPr2-bimy)CuÀSeSiMe3]2 was marked-
ly less thermally stable. Using [(iPr2-bimy)CuÀSSiMe3]2 as a pre-
cursor for ternary cluster formation led to the high nuclearity
[(iPr2-bimy)6Cu10S8Hg3], thus demonstrating the dramatic effect
of changing surface ligands in this system. The strategy out-
lined above for the synthesis of NHC stabilized metal chal-
cogenolate complexes offers a powerful new route into a varie-
ty of binary and ternary metal–chalcogen clusters.
Synthesis of [(IPr)Ag-SSiMe3] (1): S(SiMe3)2 (38 mL, 0.18 mmol) was
added to the cold (À708C) solution of one equivalent of [(IPr)-
AgOAc] (100 mg, 0.18 mmol) in tetrahydrofuran (10 mL), followed
by storing the solution at À258C overnight. The reaction was lay-
ered with pentane (30 mL) at this temperature. Colorless, block-like
single crystals formed after 3–4 days. The crystals were washed
with 310 mL cold pentane (À708C) and dried under dynamic
vacuum (75% yield); m.p. 175–1798C.
Experimental Section
All of the syntheses were carried out under an atmosphere of
high-purity dried nitrogen using standard double-manifold Schlenk
line techniques and nitrogen-filled glove boxes unless otherwise
stated. Solvents were dried and collected using an MBraun MB-SP
Series solvent purification system with tandem activated alumina
(tetrahydrofuran) and an activated alumina/copper redox catalyst
(pentane). Chlorinated solvents ([D]chloroform, [D2]dichloro-
methane) were dried and distilled over P2O5. Other chemicals were
used as received from commercial sources (Alfa Aesar and Aldrich).
[(IPr)AgOAc],[15] (iPr2-bimy)·HI,[16] and E(SiMe3)2 (E=S, Se)[5d,17] were
synthesized according to previously reported procedures.
Performing the reaction in CDCl3 at À408C and maintaining the so-
lution at À258C confirmed the concomitant formation of [(IPr)AgÀ
1
SSiMe3] and the side product AcOSiMe3 by H NMR spectroscopy.
1H NMR for 1 (CDCl3, 599.36 MHz, 258C): d 7.46 (t, J=7.6 Hz, 2H,
para-CH), 7.28 (d, J=7.6 Hz, 4H, meta-CH), 7.18 (s, 2H, NCH), 2.56
(sept., J=7.0 Hz, 4H, CH(CH3)2), 1.29 (d, J=7.0 Hz, 12H, CH(CH3)2),
1.20 (d, J=7.0 Hz, 12H, CH(CH3)2), À0.13 ppm (s, 9H, -Si(CH3)3);
13C{1H} NMR (CDCl3, 100.53 MHz, À308C): 145.3 (ortho-C), 134.5
(ipso-C), 130.3 (para-C), 124.0 (meta-C), 123.1 (NCH), 28.5 (CH(CH3)2),
24.9 (CH(CH3)2), 23.9 (CH(CH3)2), 7.0 ppm (-Si(CH3)3). Anal. calcd (%)
for C30H45AgN2SSi: C 59.88, H 7.45, N 4.66, S 5.33; found: C 60.02,
H 7.56, N 4.63, S 4.32.
NMR spectra were recorded on Varian Mercury 400, Inova 400, and
Inova 600 NMR spectrometers. 1H and 13C{1H} chemical shifts are
referenced to SiMe4, using solvent peaks as a secondary reference.
Elemental analysis was performed by Laboratoire d’Analyze Éle-
mentaire de l’UniversitØ de MontrØal, MontrØal, Canada. Samples
were dried for about twelve hours prior to send for analysis. Exper-
imentally obtained values of elemental analysis and NMR spectra
suggests some residual lattice solvent remained for 4 (ca. 0.75THF
molecule per molecular formula).
Synthesis of [(IPr)Ag-SeSiMe3] (2): Se(SiMe3)2 (35 mL, 0.14 mmol)
was reacted with one equivalent of [(IPr)AgOAc] (78 mg,
0.14 mmol) in tetrahydrofuran (10 mL) as described for the prepa-
ration of 1. Colorless block single crystals suitable for X-ray diffrac-
tion were obtained after five to six days by layering the mother
liquor with 30 mL of pentane at À258C (55% yield); m.p. 170–
1758C.
Single-crystal X-ray diffraction measurements were completed on
a Bruker APEX-II CCD diffractometer equipped with graphite-mono-
chromated Mo Ka (l=0.71073 ) radiation. Single crystals of the
complexes were carefully selected, immersed in paraffin oil, and
mounted on MiteGen micromounts. The structures were solved
using direct methods and refined by the full-matrix least-squares
procedure of SHELXTL.[18] All non-hydrogen atoms, with the excep-
tion of disordered carbon centers, were refined with anisotropic
thermal parameters. For 3, the TWIN command in SHELXTL was
used to refine the structure. In 6, some of the disordered THF sol-
vents in the crystal packing were removed by the SQUEEZE pro-
gram.
1
Monitoring this reaction by H NMR spectroscopy in CDCl3 showed
1
the formation of 2 and trimethylsilylacetate. H NMR for 2 (CDCl3,
399.76 MHz, À308C): d 7.47 (t, J=7.8 Hz, 2H, para-CH), 7.28 (d, J=
7.8 Hz, 4H, meta-CH), 7.21 (s, 2H, NCH), 2.51 (sept., J=7.0 Hz, 4H,
CH(CH3)2), 1.30 (d, J=7.0 Hz, 12H, CH(CH3)2), 1.20 (d, J=7.0 Hz,
12H, CH(CH3)2), À0.02 ppm (s, 9H, -Si(CH3)3); 13C{1H} NMR (CDCl3,
100.53 MHz, À308C): 145.3 (ortho-C), 134.5 (ipso-C), 130.3 (para-C),
124.0 (meta-C), 123.1 (NCH), 28.5 (CH(CH3)2), 25.0 (CH(CH3)2), 23.8
(CH(CH3)2), 7.6 ppm (-Si(CH3)3). Anal. calcd (%) for C30H45AgN2SeSi:
C 55.55, H 6.99, N 4.32; found: C 55.59, H 7.10, N 4.25.
Chem. Eur. J. 2016, 22, 4543 – 4550
4548
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