Trivalent Lanthanide Chalcogenolates: Ln(SePh)3, Ln2(EPh)6, Ln4(SPh)12, and [Ln(EPh)3]n (E = S, Se). How Metal, Chalcogen, and Solvent Influence Structure

Article abstract of DOI:10.1021/ic9716161

A series of trivalent lanthanide (Ln) benzenechalcogenolate (EPh, E = S, Se) complexes have been prepared and structurally characterized in an attempt to evaluate how metal size, chalcogen, and solvent influence structure and physical properties. The compounds [(Py)₃Ln(SPh)₃]₂ (Ln = Ho (1) and Tm (2)), [(py)₂Sm(SPh)₃]₄ (3), [(THF)Sm(SPh)₃]_4n (4), (THF)₃Ln(SePh)₃ (Ln = Tm (5), Ho (6), Er (7)), [(py)₃Sm(SePh)₃]₂ (8), and [(THF)₄Ln3-(SePh)₉]_n (Ln = Pr (9), Nd (10), and Sm (11)) were isolated and characterized by IR, NMR, and UV-visible spectroscopy. Compounds 2-4, 7, 8, and 10 have also been characterized by low-temperature single-crystal X-ray diffraction. Three trends in structure are clear. First, the tendency to form oligomeric structures is found to increase with the size of the lanthanide ion. Second, thiolates bridge metal ions to form polynuclear structures more effectively than selenolates. Finally, pyridine displaces bridging chalcogenolates to form less extended structures more effectively than THF. Compounds 5-7 are molecular fac-octahedral complexes, compounds 1, 2, and 8 are bimetallic molecules with a pair of chalcogen atoms spanning the pentagonal bipyramidal metal centers, compound 3 is a tetrametallic structure with an alternating (3-2-3) number of μ2-thiolates spanning the linear assembly of four seven-coordinate Sm(III) ions, and compounds 4, 9, 10, and 11 are polymers with sets of three doubly bridging benzenechalcogenolates connecting adjacent metal ions. Resonance Raman spectroscopy indicates that the intense electronic absorption associated with Sm(III) chalcogenolate is a chalcogen-to-metal charge-transfer excitation. Compounds 1 and 2 decompose thermally to give Ln₂S₃.

Full text of DOI:10.1021/ic9716161

2512
Inorg. Chem. 1998, 37, 2512-2519
Trivalent Lanthanide Chalcogenolates: Ln(SePh)3, Ln2(EPh)6, Ln4(SPh)12, and [Ln(EPh)3]n
(E ) S, Se). How Metal, Chalcogen, and Solvent Influence Structure
Jongseong Lee, Deborah Freedman, Jonathan H. Melman, Meggan Brewer, Lei Sun,
T. J. Emge, F. H. Long, and John G. Brennan*
Department of Chemistry, Rutgers, the State University of New Jersey, 610 Taylor Road,
Piscataway, New Jersey 08854-8087
ReceiVed December 29, 1997
A series of trivalent lanthanide (Ln) benzenechalcogenolate (EPh, E ) S, Se) complexes have been prepared and
structurally characterized in an attempt to evaluate how metal size, chalcogen, and solvent influence structure
and physical properties. The compounds [(py)3Ln(SPh)3]2 (Ln ) Ho (1) and Tm (2)), [(py)2Sm(SPh)3]4 (3),
[(THF)Sm(SPh)3]4n (4), (THF)3Ln(SePh)3 (Ln ) Tm (5), Ho (6), Er (7)), [(py)3Sm(SePh)3]2 (8), and [(THF)4Ln3-
(SePh)9]n (Ln ) Pr (9), Nd (10), and Sm (11)) were isolated and characterized by IR, NMR, and UV-visible
spectroscopy. Compounds 2-4, 7, 8, and 10 have also been characterized by low-temperature single-crystal
X-ray diffraction. Three trends in structure are clear. First, the tendency to form oligomeric structures is found
to increase with the size of the lanthanide ion. Second, thiolates bridge metal ions to form polynuclear structures
more effectively than selenolates. Finally, pyridine displaces bridging chalcogenolates to form less extended
structures more effectively than THF. Compounds 5-7 are molecular fac-octahedral complexes, compounds 1,
2, and 8 are bimetallic molecules with a pair of chalcogen atoms spanning the pentagonal bipyramidal metal
centers, compound 3 is a tetrametallic structure with an alternating (3-2-3) number of µ2-thiolates spanning the
linear assembly of four seven-coordinate Sm(III) ions, and compounds 4, 9, 10, and 11 are polymers with sets of
three doubly bridging benzenechalcogenolates connecting adjacent metal ions. Resonance Raman spectroscopy
indicates that the intense electronic absorption associated with Sm(III) chalcogenolate is a chalcogen-to-metal
charge-transfer excitation. Compounds 1 and 2 decompose thermally to give Ln2S3.
Introduction
and by the potential applications of these compounds for the
synthesis of doped semiconductor,6 fiber optic,7 and pigment
materials.8
The extent to which covalency contributes to the stability of
Ln-E bonds remains an unanswered question. Lanthanide
coordination chemistry has always been discussed in terms of
ionic bonding, but there are compounds that have been described
in more covalent terms.9 While the Ln valence 4f shell is
effectively shielded, these metals do have vacant 5d, 6s, and
6p orbitals that could overlap with ligand-based orbitals.10 The
The synthesis and characterization of lanthanide complexes
in which chalcogenolates are the only anionic ligands [Ln(ER)x:
Ln ) La-Yb; E ) S, Se, Te; R ) Ph,1 substituted Ph,2 SiR′3,3
2-NC5H4,4 CR′3;5 x ) 2, 3) are motivated by fundamental
questions related to the nature of the lanthanide-chalcogen bond
(1) (a) Berardini, M.; Emge, T.; Brennan, J. G. J. Chem. Soc., Chem.
Commun. 1993, 1537. (b) Berardini, M.; Emge, T.; Brennan, J. G. J.
Am. Chem. Soc. 1993, 115, 8501. (c) Khasnis, D. V.; Lee, J.; Brewer,
M.; Emge, T. J.; Brennan, J. G. J. Am. Chem. Soc. 1994, 116, 7129.
(d) Brewer, M.; Khasnis, D.; Buretea, M.; Berardini, M.; Emge, T. J.;
Brennan, J. G. Inorg. Chem. 1994, 33, 2743. (e) Berardini, M.; Emge,
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Brewer, M.; Berardini, M.; Brennan, J. Inorg. Chem. 1995, 34, 3215.
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5327. (i) Geissinger, M.; Magull, J. Z. Anorg. Allg. Chem. 1995, 621,
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J. Am. Chem. Soc. 1992, 114, 3159. (b) Mashima, K.; Nakayama, Y.;
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Hitchcock, P. B.; Hu, J.; Lappert, M. F.; Dilworth, J. R. J. Chem.
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Mashima, K.; Shibahara, T.; Nakayama, Y.; Nakamura, A. J. Orga-
nomet. Chem. 1995, 501, 263. (c) Berardini, M.; Lee, J.; Freedman,
D.; Lee, J.; Emge, T. J.; Brennan, J. G. Inorg. Chem. 1997, 36, 5772.
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S0020-1669(97)01616-9 CCC: $15.00 © 1998 American Chemical Society
Published on Web 05/02/1998

Trivalent Lanthanide Chalcogenolates
Inorganic Chemistry, Vol. 37, No. 10, 1998 2513
Anhydrous pyridine (Aldrich) was purchased and refluxed over KOH.
PhSeSePh and PhSSPh were purchased from either Aldrich or Strem
and recrystallized from hexane. Ln and Hg were purchased from Strem.
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 450 cm-1 as a Nujol mull on KBR 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 Quantitative Technologies, Inc.
(Salem, NJ). These compounds are sensitive to the thermal dissociation
of neutral donor ligands at room temperature and so the experimentally
determined elemental analyses are generally found to be lower than
the computed analyses. Products appear homogeneous, and for every
sample several crystals of each compound were examined by single-
crystal X-ray diffraction in an attempt to find a crystal suitable for a
complete structural determination. The same unit cell was obtained
consistently for each compound. Twinning and a likely phase transition
were found to be problematic in a number of samples. NMR spectra
were obtained on either a Varian Gemini 200 MHz or Varian 400 MHz
NMR spectrometer at 23 °C and are reported in δ (ppm). Powder
diffraction spectra were obtained from a Scintag Pad V diffractometer
and Cu KR radiation. Raman spectra were recorded using a Coherent
Innova 90 Ar/Kr mixed gas laser, a Spex model 1877E triple
monochromator, and a Spex spectrum one charge-coupled-detector
cooled with liquid nitrogen. Blue (488 nm), green (514 nm), and yellow
(567 nm) light were used. The average power irradiating the sample
was 100 mW. A laser prefilter Spex model 1450 was used to reject
plasma lines from the laser tube. The samples were held at room
temperature in a cuvette sealed with a Teflon stopcock and aligned
such that the collection of scattered light was in a backscattered
geometry. The polarization of the laser light, both incident and
collected, was unspecified. Calibration of the Raman spectra was
carried out using known atomic emission lamps and is accurate to
physical and chemical properties of Ln(EPh)3 compounds are
also crucial reference points for interpreting the bonding and
physical properties of lanthanide chalcogenido clusters.3a,11,12
From an applied perspective, these chalcogenolate complexes
are uniquely suited for delivering Ln ions into chalcogenido
materials6,7 because ER ligands are excellent leaving groups.
Such reactivity was noted recently in the synthesis of the [Sm7S7-
(SePh)6(DME)7]+ and Gd8S6(SPh)12(THF)8 from the reactions
of Ln(EPh)3 with elemental S.11 The facility with which ER
ligands are displaced at room temperature suggests that Ln-
(ER)3 will find numerous synthetic applications. Importantly,
the thiolate study11b illustrated that the redox inactive Ln ions
are potentially as reactive as the redox active (Ln2+/3+) Sm, Eu,
and Yb. Such reactivity provides additional impetus for
investigating the synthetic chemistry and the physical properties
of all Ln(ER)3, particularly given the unusual structural/reactivity
trends noted in lanthanide chloride chemistry.13
This manuscript extends our initial efforts in Ln(EPh)3
chemistry to the middle of the lanthanide series. The synthesis
and characterization of [(py)3Ln(SPh)3]2 (Ln ) Ho (1) and Tm
(2)), [(py)2Sm(SPh)3]4 (3), [(THF)Sm(SPh)3]4n (4), (THF)3Ln-
(SePh)3 (Ln ) Tm (5), Ho (6), Er (7)), [(py)3Sm(SePh)3]2 (8),
and [(THF)4Ln3(SePh)9]n (Ln ) Pr (9), Nd (10), and Sm (11))
are described. The effect of metal size, chalcogenolate, and
neutral donors on solid-state structure is assessed, and the
assignment of the electronic spectra of the redox active Ln-
(ER)3 compounds to a LMCT excitation is confirmed by
resonance Raman spectroscopy.
Experimental Section
approximately 1 cm-1
.
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 sodium/benzophenone and collected immediately prior to use.
Synthesis of [(pyridine)3Ho(SPh)3]2 (1). Ho (0.66 g, 4.0 mmol),
Ph2S2 (1.31 g, 6 mmol), and Hg (55 mg, 0.27 mmol) were added to
pyridine (40 mL), and the mixture was stirred for 3 days as the solution
color turned peach. The solution was filtered, concentrated to 20 mL,
and layered with diethyl ether (60 mL). After 1 day, peach colored
crystals (2.10 g, 72%; mp 127 °C) were collected. Anal. Calcd for
C33H30N3HoS3: C, 54.0; H, 4.12; N, 5.72. Found: C, 50.1; H, 3.86;
N, 5.47. IR: 2922 (b), 2743 (s), 2669 (s), 1949 (s), 1862 (s), 1633
(s), 1577 (m), 1477 (m), 1376 (m), 1303 (s), 1261 (m), 1218 (m), 1147
(m), 1082 (s), 1026 (m) 894 (s), 803 (s), 734 (m), 700 (m), 602 (s),
(7) (a) Wang, J.; Hector, J. R.; Payne, D. N. Appl. Phys. Lett. 1997, 71,
1753. (b) Jurdyc, A. M.; Garapon, C.; Adam, J. L. J. Non-Cryst. Solids
1997, 213/4, 231. (c) Quimby, R. S.; Aitken, B. G. J. Appl. Phy. 1997,
82, 3992. (d) Schweizer, T.; Hewak, D. W.; Payne, D. N. Opt. Lett.
1996, 21, 1594. (e) Kumta, P. K.; Risbud, S. H. J. Mater. Sci. 1994,
29, 1135. (f) Kumta, P. K.; Risbud, S. H, Prog. Cryst. Growth Char.
1991, 22, 321. (g) Nishii, J.; Morimoto, S.; Yokota, R.; Yamagishi,
T. J. Non-Cryst. Solids 1987, 95/6, 641. (h) Savage, J. A. In Infrared
Optical Materials and Their Antireflection Coatings; Adam Hilger
Ltd.: Bristol, U.K., 1985; pp 79-94. (i) Nishii, J.; Morimoto, S.;
Inagawa, I.; Iizuka, R.; Yamashita, T.; Yokota, R.; Yamagishi, T J.
Non-Cryst. Solids 1982, 140, 199. (j) Sanghara, J. S.; Busse, L. E.;
Aggarwall, I. D. J. Appl. Phys. 1994, 75, 4885. (k) Katsugama, T.;
Matsumura, H. J. Appl. Phys. 1994, 75, 2743.
(8) (a) Chopin, T.; Guichon, H.; Touret, O. U.S. Patent No. 5, 348, 581,
1994. (b) Chopin; T.; Dupuis; D. U.S. Patent No. 5, 401, 309, 1995.
(9) (a) King, W. A.; Di Bella, S.; Marks, T. J. J. Am. Chem. Soc. 1996,
118, 627. (b) King, W. A.; Marks, T. J.; Anderson, D. M. J. Am.
Chem. Soc. 1992, 114, 9221. (c) Brennan, J.; Cloke, F. G. N.; Sameh,
A.; Zalkin, A. J. Chem. Soc. Chem. Commun. 1987, 1668. (d)
Anderson, D.; Cloke, F. G. N.; Cox, P.; Edelstein, N.; Green, J.; Pang,
T.; Sameh, A.; Shalimoff, G. J. Chem. Soc., Chem. Commun. 1989,
53. (e) Anderson, D.; Cloke, F. G. N.; Cox, P. J. Chem. Soc., Chem.
Commun. 1990, 284.
1
480 (m), 412 (m) cm-1. No H NMR (20 mgs in 0.50 mL of CD3S-
(O)CD3) resonances were detected. The compound does not show a
λmax from 350 to 800 nm in either THF or pyridine. Unit cell (Mo KR
radiation, -120 °C): a ) 24.154(6) Å, b ) 14.214(5) Å, c ) 20.580-
(8) Å, â ) 96.43(2)°, V ) 7021(4) Å3. Thermolysis: 1 (650 mg) was
placed in a Pyrex tube under vacuum for 1 h. The tube was then sealed,
and the sample temperature was raised over a period of 3 days from
50 to 300 °C, with one end of the tube kept at room temperature.
Between 80 and 100 °C, a colorless liquid (pyridine) condensed in the
part of the tube that was outside the furnace. Between 250 and 300
°C, yellow diphenyl sulfide condensed in the cold part of the sample
holder. The volatile materials were identified by 1H NMR spectroscopy.
The remaining black solid (220 mg, 100.6%) was transferred to a quartz
tube that was then sealed under vacuum (10-7 Torr). Further heating
(1000 °C, 3 days) showed no further elimination of volatile products,
and an X-ray powder diffraction spectrum of the final solid product
revealed the presence of microcrystalline Ho2S3.14 Similarly, ther-
molysis of 2 gave Tm2S3.15
(10) (a) Gerth, G.; Kienle, P.; Luchner, K. Phys. Lett. A 1968, 27, 557. (b)
Eatough, N. L.; Hall, H. T. Inorg. Chem. 1970, 9, 417. (c) Dagys, R.
S.; Anisimov, F. G. SoV. Phys. Solid State 1984, 26, 547. (d) Wachter,
P. Crit. ReV. Solid State 1972, 3, 189. (e) Byrom, E.; Ellis, D. E.;
Freeman, A. J. Phys. ReV. B 1976, 14, 3558. (f) Zhukov, V. P.;
Gubanov, V. A.; Weber, J. J. Chem. Phys. Solids 1981, 42, 631.
(11) (a) Freedman, D.; Emge, T. J.; Brennan, J. G. J. Am. Chem. Soc. 1997,
119, 11112. (b) Melman, J. H.; Emge, T. J.; Brennan, J. G. Chem.
Commun. 1997, 2269.
Synthesis of [(pyridine)3Tm(SPh)3]2 (2). Tm (0.68 g, 4.0 mmol),
Ph2S2 (1.31 g, 6 mmol), and Hg (55 mg, 0.27 mmol) were added to
pyridine (40 mL), and the mixture was stirred for 3 days as the solution
color turned yellow green. The solution was filtered, concentrated to
20 mL, and layered with diethyl ether (60 mL). After 1 day, yellow
green crystals (2.42 g, 82.3%; mp 110 °C) were collected. Anal. Calcd
(12) (a) Evans, W. J.; Rabe, G.; Ziller, J. Angew. Chem., Int. Ed. Engl.
1994, 33, 2110. (b) Pernin, C. G.; Ibers, J. A. Inorg. Chem. 1997, 36,
3802.
(13) Evans, W. J.; Shreeve, J. L.; Doedens, R. J. Inorg. Chem. 1995, 34,
576.
(14) JCPDS File 44-1156.
(15) JCPDS File 44-1157.

2514 Inorganic Chemistry, Vol. 37, No. 10, 1998
Lee et al.
for C33H30N3TmS3: C, 54.0; H, 4.12; N, 5.72. Found: C, 48.9; H,
3.45; N, 5.54. IR: 2922 (b), 2854 (m), 1950 (m), 1861 (s), 1634 (s),
1577 (m), 1459 (m), 1377 (s), 1261 (s), 1218 (s), 1146 (s), 1067 (s),
1027 (s), 896 (m), 805 (m), 737 (m), 699 (m), 603 (m), 484 (m), 412
7.17 (2 H), 6.58 (3 H) and 3.60 (4 H), 1.75 (4 H) ppm. The compound
does not show a λmax from 350 to 800 nm in either THF or pyridine.
Synthesis of [(pyridine)3Sm(SePh)3]2 (8). Sm (0.61 g, 4.0 mmol),
Ph2Se2 (1.87 g, 5.99 mmol), and Hg (55 mg, 0.27 mmol) were added
to pyridine (40 mL), and the mixture was stirred for 3 days as the
solution color turned red. The solution was filtered, concentrated to
20 mL, and layered with diethyl ether (60 mL). After 1 day, peach
crystals (2.10 g, 61.4%; it started to lose its solvents very slowly from
135 °C and decomposed at 300 °C) were collected. Anal. Calcd for
C33H30N3Se3Sm: C, 46.3; H, 3.53; N, 4.90. Found: C, 43.28; H, 3.59;
N, 4.48. IR: 2935 (w), 2723 (s), 2668 (s), 2466 (s), 2372 (s), 2019
(s), 2310 (s) 1935 (s), 1861 (s), 1796 (s), 1735 (s), 1686 (s), 1629 (s),
1595 (m), 1456 (m), 1375 (m), 1300 (s), 1261 (s), 1216 (m), 1152
(m), 1067 (m), 1001 (m), 936 (s), 893 (s), 836 (s), 799 (s), 731 (m),
(m) cm-1 1H NMR (20 mg in 0.50 mL NC5D5) contained resonances
.
at 8.11, 7.51, and 7.15 ppm which were too broad for accurate
integration. The compound does not show a λmax from 350 to 800 nm
in either THF or pyridine.
Synthesis of [(pyridine)2Sm(SPh)3]4 (3). Sm (0.35 g, 2.4 mmol),
Ph2S2 (0.81 g, 3.7 mmol), and Hg (0.05 g, 0.24 mmol) were added to
pyridine (40 mL). After being stirred for 3 days, the resultant yellow-
green solution was filtered, concentrated to ca. 20 mL, and layered
with ether to give light yellow crystals (0.73 g, 46%; the compound
does not melt but appears to lose solvent at ca. 120 °C and decompose
at 385 °C). The compound crystallizes with one lattice diethyl ether/
Sm4 molecule. Anal. Calcd for C116H110ON8Sm4S12: C, 53.2; H, 4.23;
N, 4.28. Found: C, 45.0; H, 3.76; N, 2.49. IR: 2920 (br), 1598 (w),
1576 (w), 1461 (s), 1377 (s), 1260 (w), 1217 (w), 1083 (w), 1062 (w),
700 (s), 622 (s), 602 (s), 465 (m), 404 (m) cm-1 1H NMR (40 mg in
.
0.50 mL of NC5D5) contained resonances at 8.70 (2 H), 7.79 (1 H),
7.55 (2 H), 7.21 (3 H), and 6.96 (2 H) ppm. The visible spectrum is
concentration dependent. UV: λmax (ca. 1 mg/mL of pyridine) ) 425
nm.
1023 (w), 1004 (w), 739 (m), 700 (s), 623 (w), 601 (w) cm-1 1H
.
NMR (ca. 25 mg in 0.60 mL CD3CN) showed only resonances due to
displaced pyridine. The compound does not show a λmax from 350 to
800 nm in pyridine.
Synthesis of [(THF)4Pr3(SePh)9]n (9). Pr (286 mg, 2.0 mmol), Ph2-
Se2 (938 mg, 3.0 mmol), and Hg (50 mg, 0.25 mmol) were stirred in
THF (50 mL) for 3 days. The yellow solution was filtered, concentrated
to 30 mL, and layered with hexanes (30 mL) to give pale green needles
(0.40 g, 27%; the compounds does not melt but turns orange at ca.
200 °C and continues to darken up to 300 °C). Anal. Calcd for C70-
H77O4Pr3Se9: C, 39.8; H, 3.76. Found: C, 38.1; H, 3.82. IR: 3173
(w), 2932 (s), 2726 (w), 2343 (w), 1571 (m), 1461 (s), 1377 (s), 1306
(w), 1263 (w), 1169 (w), 1154 (w), 1067 (m) 1021 (m), 974 (w), 854
Synthesis of [(THF)Sm(SPh)3]4n (4). Sm (0.453 g, 3.01 mmol),
Ph2S2 (0.986 g, 4.52 mmol), and Hg (35 mg, 0.18 mmol) were combined
in THF (40 mL). The mixture was stirred for 24 h until metal was
consumed, and then the cloudy green solution was filtered. The
resultant yellow solution was layered with hexane to give yellow crystals
(0.363 g, 22%; the crystals do not melt but darken at 97 °C and then
progressively lose color from 280 to 300 °C). IR: 1574 (w), 1081
1
(m), 752 (s), 688 (m), 668 (w), 615 (w), 462 (w), 451 (w) cm-1 . H
(w), 858 (w), 732 (m), 689 (m), 481 (w) cm-1
.
1H NMR (OC4D8)
NMR (NC5D5, 25 °C) spectrum contained broad phenyl resonances at
6.37 (2H) and 5.26 (3H) ppm and resonances from displaced THF at
3.58 and 1.73 ppm. The compound does not show a λmax from 350 to
800 nm in either THF or pyridine. Unit cell (Mo KR radiation, -120
°C): a ) 34.793(21) Å, b ) 25.791(9) Å, c ) 26.882(11) Å, â )
130.78(4)°, V ) 18267(18) Å3.
shows only broad peaks due to displaced THF at 3.58 and 1.73 ppm.
Anal. Calcd for C22H23OS3Sm: C, 48.05; H, 4.21. Found: C, 43.40;
H, 4.13. The compound does not show a λmax from 350 to 800 nm in
THF.
Synthesis of (THF)3Tm(SePh)3 (5). Tm (0.68 g, 4.0 mmol), Ph2-
Se2 (1.87 g, 6.0 mmol), and Hg (55 mg, 0.27 mmol) were added to
THF (40 mL), and the mixture was stirred for 3 days as the solution
color turned yellow-green. The solution was filtered, concentrated to
20 mL, and layered with hexane (60 mL). After 1 day crystals (1.80
g, 53%; desolvates at 110 °C and decomposes at 310 °C) were collected.
Anal. Calcd for C30H39O3TmSe3: C, 42.2; H, 4.61. Found: C, 36.7,
38.37; H, 4.68, 3.03. IR: 2969 (b), 2748 (s), 2592 (s), 2532 (s), 2317
(s), 2317 (s), 2241 (s), 2068 (s), 1943 (m), 1865 (m), 1804 (m), 1737
(m), 1637 (m), 1567 (m), 1448 (m), 1384 (m), 1296 (m), 1263 (m),
Synthesis of [(THF)4Nd3(SePh)9]n (10). Nd (0.58 g, 4.0 mmol),
Ph2Se2 (1.89 g, 6.0 mmol), and Hg (50 mg, 0.25 mmol) were stirred in
THF (50 mL) for 2 days. The light blue solution was filtered,
concentrated (40 mL), and layered with hexanes (30 mL). Colorless
crystals formed after 1 day (2.6 g, 89%). X-ray-quality crystals were
obtained by recrystallization and layering with pentane (20 mL). The
crystals did not melt but turned gray at ca. 140 °C, light brown by 230
°C, and continued to darken up to 300 °C. Anal. Calcd for C70H77O4-
Nd3Se9: C, 39.5; H, 3.65. Found: C, 37.8; H, 3.66. IR: 3167 (w),
2911 (s), 2725 (w), 2674 (w), 2364 (w), 1571 (m), 1461 (s), 1378 (s),
1304 (w), 1208 (w), 1169 (w), 1155 (w), 1071 (m), 1019 (m), 974
(w), 915 (w), 855 (m), 826 (w), 728 (s), 689 (s), 664 (m), 614 (w),
1177 (m), 966 (b), 732 (m), 701 (m), 511 (m), 480 (m), 422 (m) cm-1
.
1H NMR (20 mg in 0.50 mL of CD3S(O)CD3) contained resonances at
7.24, 6.65 (phenyl group) and 3.68, 1.83 (THF) ppm which were too
broad for accurate integration. The compound does not show a λmax
from 350 to 800 nm in either THF or pyridine.
464 (s) cm-1 1H NMR (NC5D5N, 25 °C): phenyl protons, 6.86 (2H,
.
b), 5.59 (2H, b), and 5.27 (1H, b) and displaced THF at 3.58 and 1.73
ppm. The compound does not show a λmax from 350 to 800 nm in
either THF or pyridine.
Synthesis of (THF)3Ho(SePh)3 (6). Ho (0.66 g, 4.0 mmol), Ph2-
Se2 (1.87 g, 5.99 mmol), and Hg (55 mg, 0.27 mmol) were added to
THF (40 mL), and the mixture was stirred for 3 days as the solution
color turned pink. The solution was filtered, concentrated to 20 mL,
and layered with hexane (60 mL). After 1 day, colorless crystals (2.62
g, 77.2%; mp 120 °C (desolvates), 330 °C (dec)) were collected. Anal.
Calcd for C30H39O3HoSe3: C, 42.42; H, 4.63. Found: C, 38.16; H,
4.27. IR: 2922 (w), 2727 (s), 2677 (s), 2357 (s), 1572 (m), 1462 (m),
1377 (m), 1294 (s), 1260 (m), 1073 (m), 1080 (m), 913 (s), 855 (s),
803 (m), 731 (m), 693 (m), 664 (m), 468 (m). No 1H NMR (20 mg in
0.50 mL of CD3S(O)CD3) resonances were detected. The compound
does not show a λmax from 350 to 800 nm in either THF or pyridine.
Synthesis of (THF)3Er(SePh)3 (7). Er (0.54 g, 3.2 mmol), Hg (100
mg, 0.49 mmol), and Ph2Se2 (1.5 g, 4.8 mmol) were stirred in THF
(45 mL) for 24 h. The pale pink solution was filtered, concentrated to
ca. 30 mL, and allowed to sit at -20 °C for 1 day, after which
(THF)3Er(SePh)3 (2.3 g, 72%; mp 225 °C (dec)) was isolated as pale
pink needles. Anal. Calcd for C30H39O3ErSe3: C, 42.3; H, 4.62.
Found: C, 40.9; H, 4.70. IR: 2968 (b), 1865 (s), 1806 (s), 1734 (s),
1572 (m), 1468 (m), 1385 (s), 1330 (s), 1295 (s), 1248 (s), 1178 (s),
1036 (s), 902 (s), 859 (s), 733 (m), 695 (m), 667 (m), 468 (s) cm-1. 1H
NMR (20 mg in 0.50 mL of CD3S(O)CD3) contained resonances at
Synthesis of [(THF)4Sm3(SePh)9]n (11). Sm (0.61 g, 4.0 mmol),
Ph2Se2 (1.87 g, 5.99 mmol), and Hg (55 mg, 0.27 mmol) were added
to THF (40 mL), and the mixture was stirred for 3 days as the solution
color turned red. The solution was filtered, concentrated to 20 mL,
and layered with hexane (60 mL). After 1 day, red crystals (2.20 g,
79.7%; the compound desolvates at 135 °C and appears to decompose
at 300 °C) were collected. Anal. Calcd for C70H77O4Se9Sm3: C, 39.3;
H, 3.63. Found: C, 37.7; H, 2.85. IR: 2927 (w), 2725 (s), 2680 (s),
1946 (s), 1875 (s), 1810 (s), 1713 (s), 1571 (m), 1451 (m), 1376 (m),
1297 (s), 1260 (s), 1171 (s), 1067 (m), 1018 (m), 912 (s), 842 (m),
824 (m), 802 (s), 728 (m), 664 (m), 689 (m), 464 (m) cm-1 1H NMR
.
(20 mg in 0.50 mL of CD3S(O)CD3) contained resonances at 7.34 (18
H), 6.58 (27 H) and 3.57 (16 H), 1.72 (16 H) ppm. UV: λmax (ca. 1
mg/mL of THF) ) 409 nm. Unit cell (Mo KR radiation, -120 °C):
a ) 34.109(15) Å, b ) 25.342(8) Å, c ) 26.877(13) Å, â ) 129.08-
(3)°, V ) 18034(16) Å3.
X-ray Structure Determination of 2-4, 7, 8, and 10. Data for
2-4, 7, 8, and 10 were collected on an Enraf-Nonius CAD4 diffrac-
tometer with graphite-monochromatized Mo KR radiation (λ ) 0.710 73
Å) at low temperature. The check reflections measured every 1 h

Trivalent Lanthanide Chalcogenolates
Inorganic Chemistry, Vol. 37, No. 10, 1998 2515
Table 1. Summary of Crystallographic Details for [(py)3Tm(SPh)3]2 (2), [(py)2Sm(SPh)3]4 (3), [(THF)Sm(SPh)3]4n (4), (THF)3Er(SePh)3 (7),
[(py)3Sm(SePh)3]2 (8), and [(THF)4Nd3(SePh)9]n (10)
compound
2
3
4
7
8
10
empirical formula
fw
space group
a (Å)
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
C38H35N4S3Tm
812.81
C2/c
24.105(6)
14.228(2)
20.576(2)
90
96.50(2)
90
7011(3)
8
C60H60N4OS6Sm2
1346.18
P21/n
13.488(2)
31.085(7)
14.429(2)
90
102.37(2)
90
5909(2)
4
C88H92O4S12Sm4
2199.74
C2/c
27.780(7)
14.177(6)
44.949(13)
90
95.61(2)
90
17618(10)
8
C30H39ErO3Se3
851.75
P31c
15.272(3)
15.272(3)
7.887(1)
90
90
120
1593.1(6)
2
1.776
C35.5H32.5N3.5Se3Sm
895.38
P1h
C72H81Nd3O4.5Se9
8646.91
C2/c
34.232(9)
25.526(11)
27.358(12)
90
128.93(2)
90
18596(12)
8
10.494(6)
12.863(4)
14.584(4)
69.55(2)
80.12(3)
68.47(3)
1714(1)
2
Z
D
calc (g/cm3)
1.540
1.513
1.659
1.735
1.544
temp (°C)
λ (Å)
-120
-120
-120
-120
-120
-70
0.710 73
2.74
0.710 73
2.22
0.710 73
2.96
0.710 73
6.09
0.710 73
4.93
0.710 73
5.210
abs coeff (mm-1
)
R(F) [I > 2σ(I)]a
0.025
0.061
0.052
0.111
0.033
0.061
0.018
0.041
0.039
0.104
0.077
0.186
Rw(F2) [I > 2σ(I)]a
a Definitions: R(Fo) ) ∑||Fo| - |Fc||/∑|Fo| and Rw(F2) ) {∑[w(Fo - Fc2)2]/∑[w(Fo )]2}1/2. Additional crystallographic details are given in the
2
2
Supporting Information.
Figure 2. Molecular structure of tetrametallic [(py)2Sm(SPh)3]4 with
Figure 1. Molecular structure of dimeric [(py)3Tm(SPh)3]2 with most
most of the C and H atoms removed for clarity.
of the C and H atoms removed for clarity. Thermal ellipsoids for all
structures are shown at the 50% probability level.
showed less than 2% intensity variation for all samples except 10, which
showed an 8% decay. The data were corrected for Lorenz effects,
polarization, and absorption, the latter by a numerical (SHELX76)16
method. The structures were solved by Patterson methods (SHELXS-
86).17 All non-hydrogen atoms were refined (SHELXL93 or SHELXL97)
2
based upon Fo . All hydrogen atom coordinates were calculated with
idealized geometries (SHELXL93).18 Scattering factors (fo, f ′, f ′′) are
as described in SHELXL93. Crystallographic data and final R indices
for all compounds are given in Table 1. Significant bond distances
and angles for 2-4, 7, 8, and 10 are given in Tables 2-7, respectively.
Complete crystallographic details are given in the Supporting Informa-
tion. ORTEP diagrams19 of 2-4, 7, 8, and 10 are shown in Figures
1-6, respectively. Thermal ellipsoids are shown at the 50% probability
level.
Figure 3. Molecular structure of the repeating unit in polymeric
[(THF)Sm(SPh)3]n with most of the C and H atoms removed for clarity.
Results
Ln(SPh)3. Lanthanide benzenethiolates are conveniently
prepared in high yield by the direct reduction of disulfide with
elemental Ln, and the presence of Hg increases the rate of
product formation. The products are soluble in strong donor
solvents such as pyridine, from which the bimetallic coordination
Figure 4. Molecular structure of octahedral (THF)3Er(SePh)3 with most
of the C and H atoms removed for clarity.
complexes [(py)3Ln(SPh)3]2 (Ln ) Ho (1) and Tm (2)) can be
isolated by fractional crystallization in 70-80% yield. Both 1
and 2 were characterized by conventional methods, and 2 was
studied by low-temperature single-crystal X-ray diffraction
(Figure 1, Table 2). The Ho derivative was found to be
isostructural with 2. Complex 2 is dimeric, with a pair of µ2-
thiolates bridging the seven coordinate Tm(III) ions. There are
terminal benzenethiolate ligands in both the axial and equatorial
positions of each of the inversion related pentagonal bipyramids.
These nonredox active thiolates have the light colors that are
characteristic of lanthanide ions. The products of the thermal
(16) Sheldrick, G. M. SHELX76, Program for Crystal Structure Determi-
nation, University of Cambridge, England, 1976.
(17) Sheldrick, G. M. SHELXS86, Program for the Solution of Crystal
Structures, University of Go¨ttingen, Germany, 1986.
(18) (a) Sheldrick, G. M. SHELXL93, Program for Crystal Structure
Refinement, University of Go¨ttingen, Germany, 1993. (b) Sheldrick,
G. M. SHELXL97, Program for Crystal Structure Refinement,
University of Go¨ttingen, Germany, 1997.
(19) (a) Johnson, C. K. ORTEP II; Report ORNL-5138; Oak Ridge National
Laboratory: Oak Ridge, TN, 1976. (b) Zsolnai, L. XPMA and
ZORTEP, Programs for Interactive ORTEP Drawings, University of
Heidelberg, Germany, 1997.

2516 Inorganic Chemistry, Vol. 37, No. 10, 1998
Lee et al.
Table 3. Significant Bond Lengths (Å) and Angles (deg) for
a
[(py)2Sm(SPh)3]4
Sm(1)-N(2)
Sm(1)-S(2)
Sm(1)-S(1)′
Sm(1)-S(5)
Sm(2)-N(3)
Sm(2)-S(4)
Sm(2)-S(3)
S(1)-C(1)
2.517(9)
2.785(3)
2.842(3)
2.847(3)
2.647(9)
2.756(3)
2.903(3)
1.775(11)
1.775(11)
1.758(11)
1.804(14)
Sm(1)-N(1)
Sm(1)-S(1)
Sm(1)-S(3)
Sm(2)-N(4)
Sm(2)-S(6)
Sm(2)-S(2)
Sm(2)-S(5)
S(1)-Sm(1)′
S(3)-C(13)
S(5)-C(19)
2.535(9)
2.825(3)
2.844(3)
2.581(10)
2.752(3)
2.891(3)
2.906(3)
2.842(3)
1.765(11)
1.781(12)
S(2)-C(7)
Figure 5. Molecular structure of dimeric [(py)3Sm(SePh)3]2 with most
of the C and H atoms removed for clarity.
S(4)-C(25)
S(6)-C(31)
C(1)-S(1)-Sm(1)
C(7)-S(2)-Sm(1)
120.3(4) C(1)-S(1)-Sm(1)′
122.2(4) C(7)-S(2)-Sm(2)
120.6(4)
111.7(4)
C(13)-S(3)-Sm(1) 115.7(3) C(13)-S(3)-Sm(2) 117.9(4)
C(25)-S(4)-Sm(2) 114.0(5) C(19)-S(5)-Sm(1) 118.4(4)
C(19)-S(5)-Sm(2) 117.2(4) C(31)-S(6)-Sm(2) 117.6(4)
a Symmetry transformations used to generate equivalent atoms: (′)
-x + 1, -y + 1, -z.
Table 4. Significant Bond Lengths (Å) and Angles (deg) for
a
[(THF)Sm(SPh)3]4n
Sm(1)-S(3)
Sm(1)-S(1)
Sm(1)-S(2)
Sm(1)-Sm(2)
Sm(2)-S(6)
Sm(2)-S(1)
Sm(2)-S(2)
Sm(3)-O(3)
Sm(3)-S(4)
Sm(3)-S(5)
Sm(3)-S(6)
Sm(4)-S(12)′
Sm(4)-S(7)
Sm(4)-S(11)′
S(1)-C(1)
S(3)-C(13)
S(5)-C(25)
S(7)-C(37)
S(9)-C(49)
S(10)-Sm(4)′′
S(11)-Sm(4)′′
S(12)-Sm(4)′′
2.842(2)
2.854(2)
2.878(2)
4.0893(13)
2.765(2)
2.835(2)
2.896(2)
2.515(5)
2.821(2)
2.853(2)
2.893(3)
2.763(2)
2.848(2)
2.909(2)
1.771(9)
1.781(9)
1.759(9)
1.790(9)
1.766(9)
2.880(3)
2.909(2)
2.763(2)
Sm(1)-S(11)
Sm(1)-S(10)
Sm(1)-S(12)
Sm(2)-O(2)
Sm(2)-S(3)
Sm(2)-S(4)
Sm(2)-S(5)
Sm(3)-S(8)
Sm(3)-S(7)
Sm(3)-S(9)
Sm(4)-O(4)
Sm(4)-S(9)
Sm(4)-S(10)′
Sm(4)-S(8)
S(2)-C(7)
S(4)-C(19)
S(6)-C(31)
S(8)-C(43)
S(10)-C(55)
S(11)-C(61)
S(12)-C(67)
Sm(1)-O(1)
2.845(2)
2.855(2)
2.894(3)
2.414(6)
2.823(2)
2.876(3)
2.945(2)
2.815(2)
2.820(3)
2.869(2)
2.480(6)
2.784(3)
2.880(3)
2.949(2)
1.770(9)
1.753(9)
1.795(9)
1.775(9)
1.770(8)
1.759(9)
1.772(9)
2.479(6)
Figure 6. Molecular structure of the repeating unit in polymeric
[(THF)4Nd3(SePh)9]n with most of the C and H atoms removed for
clarity.
Table 2. Significant Bond Lengths (Å) and Angles (deg) for
a
[(py)3Tm(SPh)3]2
Tm-N(2)
Tm-N(3)
Tm-S(2)
Tm-S(1)′
S(1)-Tm′
S(3)-C(13)
2.448(3)
2.506(3)
2.7126(10)
2.8258(11)
2.8257(11)
1.766(3)
Tm-N(1)
Tm-S(3)
Tm-S(1)
S(1)-C(1)
S(2)-C(7)
2.453(3)
2.6980(11)
2.7914(10)
1.769(3)
1.766(4)
N(2)-Tm-N(1)
N(1)-Tm-N(3)
N(1)-Tm-S(3)
N(2)-Tm-S(2)
N(3)-Tm-S(2)
N(2)-Tm-S(1)
N(3)-Tm-S(1)
S(2)-Tm-S(1)
N(1)-Tm-S(1)′
S(3)-Tm-S(1)′
S(1)-Tm-S(1)′
C(1)-S(1)-Tm′
C(7)-S(2)-Tm
147.14(9)
93.04(10)
91.54(8)
79.08(7)
85.15(7)
137.13(6)
84.21(7)
141.19(3)
137.06(7)
84.19(3)
62.37(3)
119.24(11)
117.50(11)
N(2)-Tm-N(3)
N(2)-Tm-S(3)
N(3)-Tm-S(3)
N(1)-Tm-S(2)
S(3)-Tm-S(2)
N(1)-Tm-S(1)
S(3)-Tm-S(1)
N(2)-Tm-S(1)′
N(3)-Tm-S(1)′
S(2)-Tm-S(1)′
C(1)-S(1)-Tm
Tm-S(1)-Tm′
C(13)-S(3)-Tm
86.60(10)
91.85(7)
173.75(6)
68.17(7)
100.51(3)
75.26(7)
92.86(3)
75.80(7)
89.56(7)
154.59(2)
118.01(11)
117.63(3)
122.95(12)
C(1)-S(1)-Sm(2)
C(7)-S(2)-Sm(1)
C(13)-S(3)-Sm(2)
C(19)-S(4)-Sm(3)
C(25)-S(5)-Sm(3)
C(31)-S(6)-Sm(2)
C(37)-S(7)-Sm(3)
C(43)-S(8)-Sm(3)
C(49)-S(9)-Sm(4)
121.4(3) C(1)-S(1)-Sm(1)
104.2(3) C(7)-S(2)-Sm(2)
125.1(3) C(13)-S(3)-Sm(1)
115.6(3) C(19)-S(4)-Sm(2)
117.8(3) C(25)-S(5)-Sm(2)
119.2(3) C(31)-S(6)-Sm(3)
119.2(3) C(37)-S(7)-Sm(4)
104.3(3) C(43)-S(8)-Sm(4)
118.2(3) C(49)-S(9)-Sm(3)
114.9(3)
118.1(3)
113.7(3)
125.0(3)
115.2(3)
110.7(3)
120.6(3)
123.9(3)
116.0(3)
a Symmetry transformations used to generate equivalent atoms: (′)
1
3
-x + /2, -y + /2, -z.
decomposition of 1 and 2 were identified as Ln2S3 by X-ray
powder diffraction.
C(55)-S(10)-Sm(1) 111.2(3) C(55)-S(10)-Sm(4)′′ 118.7(3)
C(61)-S(11)-Sm(1) 118.6(3) C(61)-S(11)-Sm(4)′′ 108.4(3)
C(67)-S(12)-Sm(4)′′ 105.5(3) C(67)-S(12)-Sm(1) 118.7(3)
Toward the middle of the lanthanide series, complex solubility
decreases, but a pyridine coordination complex of Sm(SPh)3
can be isolated as light yellow crystals by fractional crystal-
lization. A low-temperature diffraction study identified the
structure as tetrametallic [(pyridine)2Sm(SPh)3]4 (3), a nonlinear
array of four Sm(III) ions having distorted seven coordinate
pentagonal bipyramidal geometries (Figure 2, Table 3). The
two exterior Sm(III) ions in 3 have terminal benzenethiolates
in both axial and equatorial positions, and these ions are bridged
to the two interior Sm ions by sets of three µ2-SPh ligands.
The two internal Sm ions are connected by a pair of µ2-SPh
ligands. The coordination sphere of each of the two inner Sm-
(III) ions are composed of five bridging PhS and two py ligands,
while the inner sphere of each exterior Sm ion contains two
pyridine, three bridging, and two terminal thiolates.
a Symmetry transformations used to generate equivalent atoms: (′)
1
1
1
1
x + /2, y - /2, z; (′′) x - /2, y + /2, z.
Crystallization of Sm(SPh)3 from THF is also possible and
results in a significantly different solid-state structure. From
the less basic solvent, light yellow [(THF)Sm(SPh)3]n (4) was
isolated from a hexane-layered solution in 22% yield. Polymer
4 (Figure 3, Table 4) was characterized by low-temperature
single-crystal X-ray diffraction and found to contain a 1D array
of seven coordinate Sm(III) ions connected through sets of three
doubly bridging SPh ligands, with a single THF ligand saturating
each Sm(III) coordination sphere. The intense yellow colors
of the two Sm thiolates are attributed to a visible S-to-Sm(III)
charge-transfer excitation.

Trivalent Lanthanide Chalcogenolates
Inorganic Chemistry, Vol. 37, No. 10, 1998 2517
Table 7. Significant Bond Lengths (Å) and Angles (deg) for
Table 5. Significant Bond Lengths (Å) and Angles (deg) for
a
a
(THF)3Er(SePh)3
[(THF)4Nd3(SePh)9]n
Er(1)-O(1)
Er(1)-O(1)′′
Er(1)-Se(1)
Se(1)-C(1)
2.347(3)
2.347(3)
2.7766(7)
1.930(6)
Er(1)-O(1)′
Er(1)-Se(1)′
Er(1)-Se(1)′′
2.347(3)
2.7766(7)
2.7765(7)
Nd(1)-O(1)
Nd(1)-Se(7)′
Nd(1)-Se(2)
Nd(1)-Se(1)
Nd(2)-Se(3)
Nd(2)-Se(2)
Nd(2)-Se(4)
Nd(3)-O(4)
Nd(3)-Se(4)
Nd(3)-Se(7)
Nd(3)-Se(5)
Se(1)-C(1)
Se(3)-C(13)
Se(5)-C(25)
Se(7)-C(37)
Se(8)-C(43)
Se(9)-C(49)
2.544(18)
2.975(5)
2.976(5)
3.050(5)
2.971(4)
2.987(5)
3.034(5)
2.428(17)
2.981(5)
3.038(4)
3.131(5)
1.885(12)
1.885(13)
1.887(13)
1.868(12)
1.873(14)
1.851(12)
Nd(1)-Se(8)′
Nd(1)-Se(3)
Nd(1)-Se(9)′
Nd(2)-O(2)
Nd(2)-Se(5)
Nd(2)-Se(6)
Nd(2)-Se(1)
Nd(3)-O(3)
Nd(3)-Se(9)
Nd(3)-Se(6)
Nd(3)-Se(8)
Se(2)-C(7)
Se(4)-C(19)
Se(6)-C(31)
Se(7)-Nd(1)′′
Se(8)-Nd(1)′′
Se(9)-Nd(1)′′
2.945(5)
2.976(5)
2.989(5)
2.407(19)
2.976(5)
2.995(5)
3.072(5)
2.443(19)
3.032(4)
3.114(4)
3.149(5)
1.886(13)
1.869(12)
1.894(12)
2.975(5)
2.945(5)
2.989(5)
O(1)-Er(1)-O(1)′
O(1)′-Er(1)-O(1)′′
O(1)′-Er(1)-Se(1)′ 172.85(8) O(1)′′-Er(1)-Se(1)′ 94.49(8)
O(1)-Er(1)-Se(1)
O(1)′′-Er(1)-Se(1)
O(1)-Er(1)-Se(1)′′
O(1)′′-Er(1)-Se(1)′′ 172.85(8) Se(1)′-Er(1)-Se(1)′′ 91.46(2)
Se(1)-Er(1)-Se(1)′′ 91.46(2) C(1)-Se(1)-Er(1) 103.28(14)
81.33(12) O(1)-Er(1)-O(1)′′
81.33(12) O(1)-Er(1)-Se(1)′
81.33(12)
92.35(8)
172.85(8) O(1)′-Er(1)-Se(1)
92.35(8) Se(1)′-Er(1)-Se(1)
94.49(8) O(1)′-Er(1)-Se(1)′′ 92.35(8)
94.49(8)
91.46(2)
a Symmetry transformations used to generate equivalent atoms: (′)
-y + 1, x - y + 1, z; (′′) -x + y, -x + 1, z.
Table 6. Significant Bond Lengths (Å) and Angles (deg) for
[(py)3Sm(SePh)3]2
a
C(1)-Se(1)-Nd(1)
C(7)-Se(2)-Nd(1)
C(13)-Se(3)-Nd(2)
C(19)-Se(4)-Nd(3)
C(25)-Se(5)-Nd(2)
C(31)-Se(6)-Nd(2)
C(37)-Se(7)-Nd(1)′′ 117.6(7) C(37)-Se(7)-Nd(3) 117.4(6)
C(43)-Se(8)-Nd(1)′′ 114.6(9) C(43)-Se(8)-Nd(3) 124.3(11)
C(49)-Se(9)-Nd(1)′′ 115.3(8) C(49)-Se(9)-Nd(3) 115.0(7)
108.1(8) C(1)-Se(1)-Nd(2)
114.5(7) C(7)-Se(2)-Nd(2)
114.1(7) C(13)-Se(3)-Nd(1) 117.1(8)
115.8(6) C(19)-Se(4)-Nd(2) 117.4(7)
111.4(8) C(25)-Se(5)-Nd(3) 115.2(10)
122.4(8) C(31)-Se(6)-Nd(3) 120.4(7)
108.7(7)
127.9(8)
Sm-N(2)
Sm-N(1)
Sm-Se(2)
Sm-Se(1)′
Se(1)-Sm′
Se(3)-C(13)
2.510(5)
2.582(5)
2.9129(14)
3.0391(14)
3.0391(14)
1.912(6)
Sm-N(3)
2.579(5)
Sm-Se(3)
Sm-Se(1)
Se(1)-C(1)
Se(2)-C(7)
2.8968(11)
2.9972(11)
1.923(6)
1.910(6)
N(2)-Sm-N(3)
N(3)-Sm-N(1)
N(3)-Sm-Se(3)
N(2)-Sm-Se(2)
N(1)-Sm-Se(2)
N(2)-Sm-Se(1)
N(1)-Sm-Se(1)
Se(2)-Sm-Se(1)
N(3)-Sm-Se(1)′
145.3(2)
84.7(2)
N(2)-Sm-N(1)
N(2)-Sm-Se(3)
83.1(2)
79.33(11)
90.09(11)
93.93(12)
96.58(4)
74.99(11)
143.14(3)
72.66(11)
84.18(11)
91.78(4)
115.3(2)
115.44(3)
a Symmetry transformations used to generate equivalent atoms: (′)
68.32(11) N(1)-Sm-Se(3)
102.21(12) N(3)-Sm-Se(2)
172.14(10) Se(3)-Sm-Se(2)
137.12(11) N(3)-Sm-Se(1)
89.82(11) Se(3)-Sm-Se(1)
82.35(4)
137.93(11) N(1)-Sm-Se(1)′
1
1
3
1
1
3
-x + /2, y - /2, -z + /2; (′′) -x + /2, y + /2, -z + /2.
green Pr (9) and deep red Sm (11) analogues indicate these
compounds are isostructural to the Nd compound. Polymers
9-11 contain a linear 1D array of Ln(III) ions bridged to
adjacent metals by a set of three µ2-SePh ligands, and an
alternating number (1-1-2) of THF ligands are coordinated to
the array of metal ions in the solid state.
N(2)-Sm-Se(1)′
Se(3)-Sm-Se(1)′ 151.88(2)
Se(2)-Sm-Se(1)′
C(1)-Se(1)-Sm
Sm-Se(1)-Sm′
Se(1)-Sm-Se(1)′
C(1)-Se(1)-Sm′
C(7)-Se(2)-Sm
64.56(3)
114.9(2)
109.4(2)
C(13)-Se(3)-Sm 114.2(2)
The visible electronic excitations of the redox active Ln(ER)3
have been attributed to a chalcogen to metal charge transfer.
Here, the assignment is confirmed by resonance Raman experi-
ments on Sm(SePh)3 and Yb(SePh)3 in pyridine solution. Figure
7 shows the Raman spectrum for Sm(SePh)3 in the region
a Symmetry transformations used to generate equivalent atoms: (′)
-x + 1, -y + 1, -z - 2.
Ln(SePh)3. Trivalent Ln(SePh)3 coordination complexes can
also be prepared by reduction of PhSeSePh with elemental Ln/
Hg. The less basic selenolate ligands are more readily displaced
by neutral donors from the Ln coordination sphere, and so both
THF and pyridine coordination compounds of Ln(SePh)3 are
considerably more soluble than their thiolate counterparts. With
the later lanthanides, the trivalent benzeneselenolates (THF)3Ln-
(SePh)3 (Ln ) Tm (5), Ho (6), Er (7)) were isolated, and the
structure of 7 was determined by low-temperature single-crystal
X-ray diffraction (Figure 4, Table 5); unit cells were obtained
to establish that 5-7 were isostructural. Complex 7 is a fac-
octahedral molecule with three crystallographically equivalent
Er-X (X ) Se, O) bonds. The complex is isostructural with
between 850 and 950 cm-1
. A clear resonance effect is
observed as the excitation laser wavelength is tuned from blue
(488 nm) to yellow (568 nm). In particular, the intensity of
the peak at approximately 900 cm-1 increases with respect to
the peak at 950 cm-1
. The existence of clear resonance
enhancement in the Raman spectra is strong experimental
evidence for a charge-transfer band.20 Further evidence for
charge transfer is found in the Raman spectra of Yb(SePh)3
(Figure 8). This molecule has a visible absorption band with a
maximum at 510 nm, and when it is excited with 514.5 nm
light, an even more dramatic resonance effect is observed.
Further work is underway to identify these and other Raman
active modes.
1i
(THF)3Yb(SePh)3 but is merohedrally twinned.
With the larger Sm ion, oligomeric structures are obtained
from both pyridine and THF. From pyridine, red [(py)3Sm-
(SePh)3]2 (8) can be isolated in 60% yield, and the structure
was determined at low temperature (Figure 5, Table 6).
Compound 8 is dimeric in the solid state, with a pair of µ2-
benzeneselenolates connecting the two pentagonal bipyramidal
metal centers. The terminal PhSe ligands occupy axial and
equatorial positions.
Discussion
The chemistry of lanthanide chalcogenolate compounds has
expanded dramatically in the past few years,1-6,21 and it is now
clear that large, sterically demanding ancillary ligands are not
necessary in order to form stable, isolable complexes. An
understanding of the relationships between metal ionic radius,
From less basic THF, the earlier lanthanide benzeneseleno-
lates crystallize as coordination polymers in ca. 80% yields.
The precise stoichiometry of the Nd complex [(THF)4Nd3-
(SePh)9]n (10) was established by low-temperature X-ray
diffraction (Figure 6, Table 7), and the unit cells of the light
(20) For a discussion of Raman spectroscopy and its applications to
inorganic chemistry, see: AdVances in Infrared and Raman Spectros-
copy; Clark, R. J. H., Hester, R. E., Eds.; Wiley Heyden Ltd.: New
York, 1975.
(21) Nief, F. Coord. Chem. ReV. 1998, in press.

2518 Inorganic Chemistry, Vol. 37, No. 10, 1998
Lee et al.
to 7,7,8 coordinate [(THF)4Ln3(SePh)9]n polymers of the early/
middle (Pr, Nd, Sm) lanthanides. Diffraction quality crystals
of (THF)nLn(SePh)3 (Ln ) Gd-Tb) were not obtained, and
solvent loss precluded a definitive analysis of the structure by
X-ray powder diffraction. The tendency to bridge larger metals
can be attributed to the diminished intercoordination sphere
repulsions. These systematic changes in structure with changing
metal size contrast significantly with the wide variety of
structures found in related metal halide coordination chemistry.13
The identity of the chalcogen clearly influences structure.
Electrostatically, the smaller, more electronegative SPh ligand
should be a stronger donor toward Ln ions than is the larger,
less electronegative SePh. The greater tendency of S to bridge
metals is reflected in the relative solubility, where, for example,
Ln(SPh)3 are sparingly soluble in THF while the selenolates
are considerably more soluble. The differing degrees of
oligomerization (i.e. [(py)3Sm(SePh)3]2 and [(py)2Sm(SPh)3]4)
can also be rationalized in terms of greater sulfur nucleophilicity,
but there are examples (i.e. (py)3Yb(SPh)3 vs [(py)3Tm(SePh)3]2)
that indicate chalcogen basicity and chalcogenolate steric effects
can have opposing effects.
Chalcogenolate steric properties appear to influence structure
not in terms of chalcogen size and repulsion within the primary
metal coordination sphere but in terms of secondary coordination
sphere interactions. Because of the generally acute Ln-E-
C(Ph) angles, an increase of chalcogen size will effectively
reduce ligand-ligand repulsion by distancing the benzene
substituent, thus permitting either an increase in coordination
number or the bridging of the sterically demanding chalcogeno-
late. This effect has been noted previously in divalent Ln(EPh)2
structures, where, for example, the difference in coordination
geometries between octahedral (py)4Yb(EPh)2 (E ) S, Se) and
the pentagonal bipyramidal (py)5Yb(TePh)2 was attributed to
the increase in chalcogen size.1d A reduction of secondary
coordination sphere ligand-ligand repulsion can also account
for the different structures of (py)3Yb(SPh)3 and [(py)3Tm-
(SePh)3]2. In these two molecules, the metal ions have nearly
identical ionic radii, and the less nucleophilic selenolates can
bridge to form a seven-coordinate structure because the benzene
substituents are, on average, 0.14 Å22 further from the Ln ion.
The same rationale can explain the different structures of 7
coordinate Sm(III) ions in polymer 4 and the alternating 7,7,8
coordinate Sm(III) ions in polymer 11. Again, displacing the
Ph group by 0.14 Å (the difference between the ionic radius of
S and Se) permits coordination of an additional THF ligand in
the Se polymer.
Figure 7. Resonance Raman spectra of Sm(SePh)3 (adsorption λmax
) 425 nm) dissolved in pyridine, between 850 and 950 cm-1 taken at
room temperature. The laser energy decreases from top to bottom. Note
the clear enhancement of the mode at 900 cm-1. Key: (a) 488.0 nm
(2.54 eV); (b) 514.5 nm (2.41 eV); (c) 568.2 nm (2.18 eV).
A comparison of Ln(EPh)x structures with compounds
containing bulkier R groups leads to the surprising conclusion
that R groups have little impact on Ln(ER)x coordination
chemistry in the solid state. The early description of lanthanide
thiolates as insoluble in all common donor solvents23 clearly
inspired the subsequent use of these sterically demanding
trisubstituted aryl, alkyl, and Si(SiR3)3 R groups on the
chalcogen in order to decrease the tendency of chalcogen to
bridge Ln ions. Somewhat surprisingly, the coordination
chemistry of these sterically hindered Ln(ER)x and the corre-
sponding Ln(EPh)x are similar. For example, both the 2,4,6-
tri-tert-butylbenzyl and benzyl thiolates form 6 coordinate
pyridine complexes with Yb(III) and the benzenethiolate forms
seven coordinate Sm(III) complexes in either THF or pyridine,2d,e
while the tri-tert-butylbenzenethiolate yields an octahedral
Figure 8. Resonance Raman spectra of Yb(SePh)3 (adsorption λmax
)
510 nm) dissolved in pyridine, between 850 and 950 cm-1 using a
514.5 nm (2.34 eV) laser excitation at room temperature. Note the clear
enhancement of the mode at 900 cm-1
.
the E and R of chalcogenolate ligands, and neutral donor ligands
and the physical, structural, and chemical properties of Ln(ER)x
complexes is slowly emerging. Trends based on solid-state
structure can be assessed, keeping in mind that solid-state and
solution structures are not necessarily related.
Both the lanthanide benzenethiolates and selenolates show
an increasing tendency to oligomerize as the size of the metal
increases. In the benzenethiolate compounds, this trend is best
illustrated in the series of pyridine coordination complexes
(py)3Yb(SPh)3,1g [(py)3Ho(SPh)3]2, and [(py)2Sm(SPh)3]4. The
benzeneselenolates, when crystallized from weak donor solvents,
show a more dramatic change from monometallic octahedral
compounds of the smaller metals (Ho, Er, Tm) (THF)3Ln(SePh)3
(22) Shannon, R. D. Acta Crystallogr. 1976, A32, 751.
(23) Gharia, K. S.; Singh, M.; Mathur, S.; Roy, R.; Sankhla, B. S. Synth.
React. Inorg. Met.-Org. Chem. 1982, 12, 337.

Trivalent Lanthanide Chalcogenolates
Inorganic Chemistry, Vol. 37, No. 10, 1998 2519
compound. Even the E-Si(SiR3)3 ligands appear to have only
a moderate effect on structure; i.e., compare the seven coordinate
selenolates of La and Ce with the 7,7,8 coordinate polymer 11
or the 7 coordinate Eu(II) complexes (i.e. the phosphine
nm, vs compound 11, λmax ) 409 nm). A LMCT assignment
would also explain the color of three coordinate Sm(SR)3, which
is described as deep orange.5a This charge transfer excitation
is shifted considerably into the visible spectrum, relative to the
yellow SPh compounds 3 and 4, because the three coordinate
Sm(III) ion is relatively electron poor and the alkyl substituent
localizes electron density on the S, thus rendering the electron
transfer from S to Sm relatively facile. The resonance Raman
experiments here show typical resonance enhancement, thus
confirming the LMCT assignment.
3b
coordination complex of Eu(SeSi(SiMe3)3)2 with the seven
coordinate Eu(SePh)2(THF)3 or octahedral (py)2Eu(SePh)2
coordination polymers.1b This lack of impact on structure can
be attributed to the flexibility of the bond angle at the chalcogen.
With terminal Ln-E-Ph angles ranging from 98 to 120°, the
steric demands of the benzene substituent are already consider-
able. Sterically “more demanding” ligands are accommodated
by simply opening the Ln-E-C angles, i.e., 116-126° in the
(THF)3Sm(SR)2 dimer, 122-7° in THF3Sm(SR)3,2d or, even
more dramatically, 163-4° in Ln(ESi(SiR3)3)2.3b
The majority of Ln(ER)x decompositions have to date yielded
the anticipated solid-state product: Ln(ER)2 gives LnE and Ln-
(ER)3 gives Ln2E3. The deviations from this behavior were
noted only in the thermolysis of the trivalent europium thiolate
Eu(SPy)4-, which decomposes to give EuS,4a and the holmium
benzeneselenolate Ho(SePh)3, which gave a mixture of HoSe/
HoSe2.1g While the Eu thermolysis is understandable in terms
of the relative instability of Eu2S3, the latter example was curious
and suggests that solution thermolysis of these molecules could
potentially lead to the formation of LnE nanoclusters. To
determine whether this reactivity could be extended to sulfido
compounds, 1 and 2 were decomposed thermally, and the solid-
state products were examined by X-ray powder diffraction.
When the thermolysis temperature was kept below 400 °C in
an attempt to isolate metastable LnS/LnS2 phase mixtures, no
crystalline product was observed in the X-ray powder diffraction
profile. Only at elevated temperatures (>550 °C) did the
thermolysis of 1 or 2 give a crystalline solid-state product that
was identified, by XRPD, as the thermodynamically stable Ln2S3
phase.
As expected, stronger bases24 displace bridging chalcogeno-
lates from Ln(III) ions more efficiently. Macroscopically, this
effect is evident in the greater solubility of Ln(SPh)3 in pyridine
relative to THF. On a molecular level, donor base strength is
evident in the structures of [(THF)4Sm3(SePh)9]n and [(py)3-
Sm(SePh)3]2. In the weaker THF donor, Sm(SePh)3 crystallizes
as a one-dimensional polymer with six bridging selenolates per
7,7,8 coordinate Sm(III) ion, whereas the stronger pyridine donor
disrupts bridging interactions more efficiently and a structure
with only two bridging benzeneselenolates per 7 coordinate
metal is observed.
The intense colors of the redox active Ln(ER)3 complexes
have been attributed, on a tentative basis, to a charge-transfer
excitation from the chalcogenolate ligand to the Ln ion. Given
the same metal (i.e. Yb(SPh)3 vs Yb(SePh)3), the energy of this
absorption decreases as the chalcogen electronegativity de-
-
creases,1h given the same chalcogen (i.e. red Eu(SPy)4 vs
colorless Tm(SPy)4-),5a the energy of the absorption decreases
as the stability of the Ln(II) ion increases, and given the same
metal and ligand, a smaller but still distinct change in energy
is noted when the solvent changes (compound 8, λmax ) 425
Acknowledgment. This work was supported by the National
Science Foundation, under Grant CHE-9628834. F.H.L. thanks
the Rutgers Research Council for support.
Supporting Information Available: Six X-ray crystallographic
files, in CIF format, are available. Access information is given on
any current masthead page.
(24) (a) Schlesener, C. J.; Ellis, A. B. Organometallics 1983, 2, 529. (b)
Brennan, J. G.; Stults, S.; Andersen, R. A.; Zalkin, A. Inorg. Chim.
Acta 1987, 139, 201. (c) Brennan, J. G.; Stults, S.; Andersen, R. A.;
Zalkin, A. Organometallics 1988, 7, 1329.
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