11934 J. Am. Chem. Soc., Vol. 123, No. 48, 2001
Kornienko et al.
to 20 mL, and layered with hexanes (3 mL) to give dark red crystals
(0.892 g, 70%) that appear to desolvate at 125 °C and decompose at
176 °C. Anal. Calcd for C62H60N10Se11.38Yb4: C, 29.4 (26.6); H, 2.38
(2.15); N, 5.55 (4.79). Found: C, 29.4 (26.7); H, 2.43 (2.13); N, 5.61
(4.97). UV-Vis (THF): 351 (ꢀ ) 4.2 × 103), 500 (ꢀ ) 1.1 × 103)
nm. The visible spectrum is featureless in pyridine. IR: 3076 (s), 2728
(s), 2669 (s), 2400 (s), 2289 (s), 2019 (s), 1912 (s), 1860 (s), 1677 (s),
1631 (s), 1596 (s), 1579 (m), 1537 (s), 1460 (w), 1377 (w), 1289 (s),
1260 (w), 1216 (s), 1192 (s), 1143 (m), 1093 (w), 1068 (w), 1020 (w),
904 (s), 874 (s), 799 (s), 757 (s), 743 (m), 722 (s), 701 (w), 661 (s),
645 (s), 623(s) cm-1. The 1H NMR spectrum (C5D5N, 20 °C) contained
resonances from rapidly exchanging free and coordinated pyridine (8.71,
7.56, 7.20 ppm).
compounds with EE ligands may be more stable than com-
pounds with E2- ligands. As yet, however, there is no evidence
to indicate the facility with which compounds containing EE2-
or E2- ligands can be interconverted.
The synthetic investigations reported here, which describe
the first high-yield syntheses of Ln clusters with (SeSe) ligands,
reveal a rich structural chemistry in which ancillary EPh (E )
S, Se, Te) ligands play a significant role in determining the
crystal and molecular structure of the isolated product. Cluster
interconversion is probed, the Ln-E-E′-R connectivity is first
noted in Ln chemistry, and the utility of these chalcogen-rich
compounds for the preparation of chalcogenido clusters or solid-
state LnSex materials is demonstrated.
Synthesis of [(py)2YbSe(SePh)]4 from 1: 1 (1.05 mg, 0.45 mmol)
and (py)4Yb(SePh)24d (1.97 mg, 2.2 mmol) were combined in pyridine
(50 mL) and the temperature was raised to 40 °C for 30 min. After 1
day the deep red solution was filtered, concentrated to 25 mL, and
layered with hexanes (10 mL) to give dark red crystals (0.46 mg, 46%)
of [(py)2YbSe(SePh)]4 that were identified7e by mp, IR, and UV-vis
spectroscopy, and low-temperature single-crystal unit cell determination.
Experimental Section
General Methods. All syntheses were carried out under ultrapure
nitrogen (JWS), using conventional drybox or Schlenk techniques.
Solvents (Fisher) were refluxed continuously over molten alkali metals
or K/benzophenone and collected immediately prior to use. Anhydrous
pyridine (Aldrich) was purchased and refluxed over KOH. PhSeSePh
and PhSSPh were purchased from Alrdich and recrystallized from
hexane. PhTeTePh was prepared according to literature procedures.9
Yb, Hg, S, Se, and Te were purchased from Strem. There appears to
be no difference in reactivity when either commercial Se/Te or freshly
sublimed Se/Te are used. Melting points were taken in sealed capillaries
and are uncorrected. IR spectra were taken on a Mattus Cygnus 100
FTIR spectrometer, and recorded from 4000 to 600 cm-1 as a Nujol
mull on NaCl plates. Electronic spectra were recorded on a Varian DMS
100S spectrometer with the samples in a 0.10 mm quartz cell attached
to a Teflon stopcock. Elemental analyses were performed by Quantita-
tive Technologies, Inc. (Whitehouse NJ). These compounds are sensitive
to the thermal dissociation of neutral donor ligands at room temperature
and lose lattice solvents within minutes. Calculated analytical values
for the lattice desolvated materials are given in parentheses. Experi-
mentally determined analyses for samples isolated from mother liquors
more than 30 min are given in parentheses. NMR spectra were obtained
on either Varian Gemini 200 MHz or Varian 300 or 400 MHz NMR
spectrometers and chemical shifts are reported in δ (ppm).
Synthesis of 1 from [(py)2YbSe(SePh)]4: Crystalline [(py)2YbSe-
(SePh)]4‚py (0.96 g, 0.39 mmol) and elemental Se (1.54 g, 1.9 mmol)
were combined in pyridine (50 mL) at room temperature. After 1 day
the solution was filtered, concentrated to 30 mL, and layered with
hexanes (3 mL) to give black-red crystals (0.51 g, 51%) of 2 that were
identified by mp, IR, UV-vis spectroscopy, and unit cell determination
by low-temperature single-crystal X-ray diffraction.
Synthesis of (py)9Yb4(µ4-Se)(µ2-SeSe)2(µ2-SeSeTe(Ph)SeSe)(SeTe-
Ph)‚py (2): Yb (346 mg, 2.0 mmol), diphenyl ditelluride (409 mg, 1.0
mmol), and Hg (50 mg, 0.25 mmol) were stirred in pyridine (30 mL)
for 24 h to give a deep violet solution with unreacted metal. Elemental
Se (355 mg, 4.5 mmol) was added and after 7 h the black/brown
solution was filtered into a tube with a diameter of 41 mm, concentrated
to 20 mL, and layered with hexanes (2 mL) to give black-red crystals
(0.773 g, 57%) that desolvate at 144 °C but do not melt up to 320 °C.
Anal. Calcd for C62H60N10Se10Te2Yb4: C, 27.8 (24.7); H, 2.25 (2.00);
N, 5.24 (4.46). Found: C, 27.7; H, 2.13; N, 4.97. UV-Vis (THF):
381 (ꢀ ) 2.7 × 103) nm. UV-Vis (pyr): 370 (ꢀ ) 8.8 × 102) nm. IR:
3076 (s), 2724 (s), 2670 (s), 2399 (s), 2289 (s), 1975 (s), 1912 (s),
1860 (s), 1677 (s), 1632 (s), 1596 (m), 1579 (m), 1536 (s), 1461 (w),
1439 (w), 1377 (w), 1306 (s), 1261 (s), 1216 (m), 1170 (s), 1144 (m),
1092 (s), 1067 (m), 1030 (m), 1005 (s), 990 (s), 947 (s), 875 (s), 799
Synthesis of (py)8Yb4(µ4-Se)(µ2-SeSe)3(µ2-SeSeSePh)(Se0.38SePh)‚
2py (1): Yb (346 mg, 2.0 mmol), diphenyl diselenide (312 mg, 1.0
mmol), and Hg (50 mg, 0.25 mmol) were stirred in pyridine (30 mL)
for 24 h to give a deep violet solution with unreacted metal. Elemental
Se (355 mg, 4.5 mmol) was added, and after 7 h the black/brown
solution was filtered into a tube with a diameter of 41 mm, concentrated
1
(s), 757 (s), 743 (m), 731 (s), 701 (w), 623 (s) cm-1. The H NMR
spectrum (NC5D5, 20 °C) contained resonances from displaced pyridine
(8.71, 7.56, and 7.20 ppm).
Synthesis of (py)8Yb4(µ3-Se)2(µ2-SeSe)2(µ2-SPh)2(SPh)2‚2py (3):
Yb (346 mg, 2.0 mmol), diphenyl disulfide (218 mg, 1.0 mmol), and
Hg (50 mg, 0.25 mmol) were stirred in pyridine (30 mL) for 24 h to
give a black-purple solution with unreacted metal. Elemental Se (355
mg, 4.5 mmol) was added, and after 2 days the deep red solution was
filtered and concentrated to 25 mL to give red crystals (0.453 g, 35%)
that do not melt but slowly turn dark orange, brown, and finally black
by 320 °C. Anal. Calcd for C74H70N10S4Se6Yb4: C, 34.4 (31.7); H,
2.73 (2.50); N, 5.45 (4.64). Found: C, (31.6); H, (2.46); N, (4.61).
UV-Vis (tert-butylpyridine): 380 (ꢀ ) 316), 445 (ꢀ ) 136) nm. IR:
3146 (s), 3077 (m), 2724 (s), 2670 (s), 2376 (s), 2290 (s), 2036(s),
1976 (s), 1912 (s), 1860 (s), 1774 (s), 1686 (s), 1656 (s), 1631 (s),
1596 (m), 1579 (w), 1538 (s), 1461 (w), 1377 (w), 1306 (s), 1261 (s),
1234 (s), 1216 (m), 1188 (s), 1170 (s), 1144 (m), 1127 (s), 1083 (s),
1068 (s), 1030 (m), 1003 (s), 991 (s), 939 (s), 889 (s), 799 (s), 744
(5) (a) Strzelecki, A. R.; Timinski, P. A.; Helsel, B. A.; Bianconi, P. A.
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1
(m), 731 (s), 701 (w), 654 (s), 621(s) cm-1. The H NMR spectrum
(NC5D5, 20 °C) contained resonances from pyridine (8.71, 7.56, and
7.20 ppm). The compound is not soluble in either THF or toluene and
is sparingly soluble in pyridine.
X-ray Structure Determination of 1-3. Data for 1-3 were
collected on an Enraf-Nonius CAD4 diffractometer with graphite
monochromatized Mo KR radiation (λ ) 0.71073 Å) at -120 °C. The
check reflections measured every hour showed less than 3% intensity
variation. The data were corrected for Lorenz effects and polarization,
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W. S.; Irgolic, K. J. J. Organomet. Chem. 1973, 38, 97.