A bipyridyl thorium metallocene: Synthesis, structure and reactivity

Article abstract of DOI:10.1039/c2dt00051b

The synthesis, structure and reactivity of a new bipy thorium metallocene have been studied. The reduction of the thorium chloride metallocene [η⁵-1,3-(Me₃C)₂C₅H ₃]₂ThCl₂ (1) with potassium graphite in the presence of 2,2′-bipyridine gives the purple bipy metallocene [η⁵-1,3-(Me₃C)₂C₅H ₃]₂Th(bipy) (2) in good yield. Complex 2 has been fully characterized by various spectroscopic techniques, elemental analysis and X-ray diffraction analysis. Complex 2 reacts cleanly with trityl chloride, silver halides and diphenyl diselenide, leading to the halide metallocenes [η⁵-1,3-(Me₃C)₂C₅H ₃]₂ThX₂ (X = Cl (1), Br (3), I (4)) and [η⁵-1,3-(Me₃C)₂C₅H ₃]₂Th(F)(μ-F)₃Th[η⁵-1,3- (Me₃C)₂C₅H₃](F)(bipy) (5), and selenido metallocene [η⁵-1,3-(Me₃C)₂C ₅H₃]₂Th(SePh)₂ (6), in good conversions. In addition, 2 cleaves the CS bond of CS₂ to give the sulfido complex, [η⁵-1,3-(Me₃C)₂C ₅H₃]₂ThS (7), which further undergoes an irreversible dimerization or nucleophilic addition with CS₂, leading to the dimeric sulfido complex {[η⁵-1,3-(Me₃C) ₂C₅H₃]₂Th}(μ-S)₂ (8) and dimeric trithiocarbonate complex {[η⁵-1,3-(Me ₃C)₂C₅H₃]₂Th}(μ- CS₃)₂ (10) in good yields, respectively.

Full text of DOI:10.1039/c2dt00051b

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PAPER
A bipyridyl thorium metallocene: synthesis, structure and reactivity†‡
Wenshan Ren,a Haibin Song,b Guofu Zi*a and Marc D. Walter*c
Received 8th January 2012, Accepted 14th March 2012
DOI: 10.1039/c2dt00051b
The synthesis, structure and reactivity of a new bipy thorium metallocene have been studied. The
reduction of the thorium chloride metallocene [η5-1,3-(Me3C)2C5H3]2ThCl2 (1) with potassium graphite
in the presence of 2,2′-bipyridine gives the purple bipy metallocene [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2)
in good yield. Complex 2 has been fully characterized by various spectroscopic techniques, elemental
analysis and X-ray diffraction analysis. Complex 2 reacts cleanly with trityl chloride, silver halides and
diphenyl diselenide, leading to the halide metallocenes [η5-1,3-(Me3C)2C5H3]2ThX2 (X = Cl (1), Br (3),
I (4)) and [η5-1,3-(Me3C)2C5H3]2Th(F)(μ-F)3Th[η5-1,3-(Me3C)2C5H3](F)(bipy) (5), and selenido
metallocene [η5-1,3-(Me3C)2C5H3]2Th(SePh)2 (6), in good conversions. In addition, 2 cleaves the CvS
bond of CS2 to give the sulfido complex, [η5-1,3-(Me3C)2C5H3]2ThS (7), which further undergoes an
irreversible dimerization or nucleophilic addition with CS2, leading to the dimeric sulfido complex
{[η5-1,3-(Me3C)2C5H3]2Th}(μ-S)2 (8) and dimeric trithiocarbonate complex {[η5-1,3-
(Me3C)2C5H3]2Th}(μ-CS3)2 (10) in good yields, respectively.
due to electron exchange coupling between the metal and ligand
Introduction
electrons.11d,15 In the area of thorium chemistry Gambarotta has
Low-valent actinide chemistry has attracted significant attention
over the years,1–7 most notably considering the expanding series
of divalent lanthanide complexes and their ability to activate
small molecules such as dinitrogen.8 In contrast, low-valent
thorium complexes are not readily accessible due to the highly
unfavorable redox-potentials9 and only a few thorium(III) com-
plexes have been thoroughly characterized.6 However, the high
reactivity of low-valent thorium complexes has previously been
demonstrated by in situ reduction of appropriate Th(IV) precur-
sors.7 Therefore, organometallic complexes that can act as syn-
thons for these otherwise difficult to access or even inaccessible
oxidation states are a desirable synthetic goal. In general, this
challenge can be met by redox non-innocent ligands such as
2,2′-bipyridine,10 1,4-diazabutadiene,5b,11 pyridine diimine12 and
arenes.13 Some of these metal complexes with redox active
ligands show fascinating properties in small molecule activation
and catalysis14 and/or unusual physical and magnetic properties
used naphthalene as a redox-active ligand to synthesize well-
characterized thorium arene complexes which act as synthons for
low-valent thorium and show a rich reaction chemistry.13c,d We
have chosen a different approach and have focused on diimine
ligands such as 2,2′-bipyridine (bipy). The bipy thorium metallo-
cene, [η5-1,2,4-(Me3C)3C5H2]2Th(bipy), has been shown to be a
useful low-valent thorium synthon for a wide range of transform-
ations.16 Encouraged by the interesting chemistry of this bipy
thorium metallocene, we have recently extended our research
work from 1,2,4-(Me3C)3C5H2 to the less sterically demanding
1,3-di-tert-butylcyclopentadienyl ligand, 1,3-(Me3C)2C5H3,17 in
order to evaluate the consequences of the reduced steric demand
on the reactivity. Herein, we report on some observations con-
cerning the chemistry of the new bipy organothorium complex,
[η5-1,3-(Me3C)2C5H3]2Th(bipy) (2).
Experimental
aDepartment of Chemistry, Beijing Normal University, Beijing 100875,
China. E-mail: gzi@bnu.edu.cn; Fax: +86-10-58802075; Tel: +86-10-
58806051
General methods
bState Key Laboratory of Elemento-Organic Chemistry, Nankai
University, Tianjin 300071, China
All reactions and product manipulations were carried out under
an atmosphere of dry dinitrogen with rigid exclusion of air and
moisture using standard Schlenk or cannula techniques, or in a
glove box. All organic solvents were freshly distilled from
sodium benzophenone ketyl immediately prior to use. 2,2′-
Bipyridine was purified by sublimation prior to use. KC8,18 and
[η5-1,3-(Me3C)2C5H3]2ThCl2 (1)19 were prepared according to
literature methods. All other chemicals were purchased from
Aldrich Chemical Co. and Beijing Chemical Co. used as
received unless otherwise noted. Infrared spectra were obtained
cInstitut für Anorganische und Analytische Chemie, Technische
Universität Braunschweig, Hagenring 30, 38106 Braunschweig,
Germany. E-mail: mwalter@tu-bs.de; Fax: +49-531-3915387;
Tel: +49-531-3915312
†Dedicated to Professor Richard A. Andersen on the occasion of his
70th birthday.
‡Electronic supplementary information (ESI) available. CCDC
860416–860420 and 869908. UV-Vis and NMR spectra. For ESI and
crystallographic data in CIF or other electronic format see DOI: 10.1039/
c2dt00051b
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from KBr pellets on an Avatar 360 Fourier transform spec-
trometer. UV-Vis spectra were recorded at 294 K in toluene sol-
ution on a TU-1901 spectrophotometer. 1H and 13C NMR
spectra were recorded on a Bruker AV 400 spectrometer at 400
and 100 MHz, respectively. All chemical shifts are reported in δ
units with reference to the residual protons of the deuterated sol-
vents, which are internal standards, for proton and carbon chemi-
cal shifts. Melting points were measured on an X-6 melting
point apparatus and were uncorrected. Elemental analyses were
performed on a Vario EL elemental analyzer.
with stirring at room temperature. During the course of the reac-
tion, the color of the solution changed from purple to colorless.
After the solution was stirred at room temperature for 4 h, the
solvent was removed. The residue was extracted with n-hexane
(10 mL × 3) and filtered. The volume of the filtrate was reduced
to 5 mL and cooled to −20 °C, yielding colorless crystals of 3,
which were isolated by filtration. Yield: 1.01 g (90%) (Found: C,
41.84; H, 5.73. C26H42Br2Th requires C, 41.83; H, 5.67%). M.
p.: 167–169 °C. 1H NMR (C6D6): δ 6.81 (t, J = 2.8 Hz, 2H, ring
CH), 6.22 (d, J = 2.8 Hz, 4H, ring CH), 1.36 (s, 36H, (CH3)3C).
13C{1H} NMR (C6D6): δ 151.7, 120.6, 113.3, 33.4, 31.6. IR
(KBr, cm−1): ν 2960 (s), 2853 (m), 1597 (m), 1460 (s), 1358 (s),
1260 (s), 1090 (s), 1018 (s), 799 (s).
Syntheses
Preparation of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2). KC8
(1.22 g, 9.0 mmol) was added to a cyclohexane (20 mL) solution
of [η5-1,3-(Me3C)2C5H3]2ThCl2 (1; 2.00 g, 3.0 mmol) and 2,2′-
bipyridine (bipy; 0.47 g, 3.0 mmol) with stirring at room temp-
erature. After this solution was stirred at 65 °C overnight the
solvent was removed. The residue was extracted with n-hexane
(10 mL × 3) and filtered. The volume of the filtrate was reduced
to 10 mL, purple crystals of 2 were isolated when this solution
was kept at room temperature for two days. Yield: 1.76 g (79%)
(Found: C, 58.17; H, 6.82; N, 3.65. C36H50N2Th requires C,
58.21; H, 6.78; N, 3.77%). M.p.: 95–97 °C (dec.). 1H NMR
(C6D6): δ 7.28 (d, J = 6.4 Hz, 2H, bipy), 6.89 (d, J = 9.6 Hz,
2H, bipy), 6.20 (d, J = 2.4 Hz, 4H, ring CH), 6.14 (m, 2H,
bipy), 5.95 (t, J = 2.4 Hz, 2H, ring CH), 5.30 (t, J = 6.0 Hz, 2H,
bipy), 1.22 (s, 36H, (CH3)3C). 13C{1H} NMR (C6D6): δ 146.3,
144.1, 122.5, 121.0, 111.6, 111.5, 110.9, 102.0, 32.9, 31.9. IR
(KBr, cm−1): ν 2961 (s), 2858 (m), 1594 (s), 1455 (m), 1359 (s),
1260 (s), 1091 (s), 1019 (s), 799 (s). UV (toluene): λmax/nm 375
(ε/M−1 cm−1 2.70 × 103), 528 (1.66 × 103).
Method B. NMR Scale. AgBr (7.6 mg, 0.04 mmol) was
added to a J. Young NMR tube charged with [η5-1,3-
(Me3C)2C5H3]2Th(bipy) (2; 14 mg, 0.02 mmol) and C6D6
(0.5 mL). The color of the solution immediately changed from
purple to colorless, and resonances due to 2 along with those of
1
2,2′-bipyridine were observed by H NMR spectroscopy (100%
conversion).
Preparation of [η5-1,3-(Me3C)2C5H3]2ThI2 (4). Method
A. This compound was prepared as colorless crystals from the
reaction of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2; 1.11 g,
1.5 mmol) and AgI (0.94 g, 4.0 mmol) in toluene (20 mL) and
recrystallization from an n-hexane solution by a similar pro-
cedure as in the synthesis of 3. Yield: 1.17 g (93%) (Found: C,
37.23; H, 4.97. C26H42I2Th requires C, 37.16; H, 5.04%). M.p.:
1
200–202 °C. H NMR (C6D6): δ 7.06 (t, J = 2.8 Hz, 2H, ring
CH), 6.20 (d, J = 2.8 Hz, 4H, ring CH), 1.37 (s, 36H, (CH3)3C).
13C{1H} NMR (C6D6): δ 152.4, 121.4, 113.2, 33.5, 31.8. IR
(KBr, cm−1): ν 2961 (s), 2856 (s), 1580 (m), 1459 (s), 1385 (s),
1358 (s), 1260 (s), 1089 (s), 1019 (s), 800 (s).
Reaction of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2) with Ph3CCl.
NMR Scale. Ph3CCl (11 mg; 0.04 mmol) was added to a
J. Young NMR tube charged with [η5-1,3-(Me3C)2C5H3]2Th-
(bipy) (2; 15 mg, 0.02 mmol) and C6D6 (0.5 mL). The color of
the solution immediately changed from purple to colorless, and
Method B. NMR Scale. AgI (9.4 mg, 0.04 mmol) was
added to a J. Young NMR tube charged with [η5-1,3-
(Me3C)2C5H3]2Th(bipy) (2; 14 mg, 0.02 mmol) and C6D6
(0.5 mL). The color of the solution immediately changed from
purple to colorless, and resonances due to 4 along with those of
1
resonances due to
1
along with those of Ph3CCH
2,2′-bipyridine were observed by H NMR spectroscopy (100%
(C2H2)2CvCPh2 (1H NMR (C6D6): δ 7.29 (m, 3H, phenyl),
7.00 (m, 22H, phenyl), 6.43 (d, J = 9.8 Hz, 2H, CH), 5.92 (t, J
= 9.8 Hz, 2H, CH), 4.92 (s, 1H, CH))20 and 2,2′-bipyridine (1H
NMR (C6D6): δ 8.72 (d, J = 8.0 Hz, 2H), 8.53 (d, J = 4.0 Hz,
2H), 7.22 (t, J = 1.8 Hz, 2H), 6.68 (m, 2H))16 were observed by
1H NMR spectroscopy (100% conversion).
conversion).
Preparation of [η5-1,3-(Me3C)2C5H3]2Th(F)(μ-F)3Th[η5-1,3-
(Me3C)2C5H3](F)(bipy) (5). AgF (0.38 g, 3.0 mmol) was added
to a benzene (20 mL) solution of [η5-1,3-(Me3C)2C5H3]2Th-
(bipy) (2; 1.11 g, 1.5 mmol) with stirring at room temperature.
After the solution was stirred at room temperature overnight, the
solvent was removed. The residue was extracted with n-hexane
(10 mL × 3) and filtered. The volume of the filtrate was reduced
to 5 mL and cooled to −20 °C, yielding colorless crystals of 5,
which were isolated by filtration. Yield: 0.60 g (64% based on
Th) (Found: C, 47.23; H, 5.78; N, 2.19. C49H71F5N2Th2 requires
C, 47.19; H, 5.74; N, 2.25%). M.p.: > 300 °C. 1H NMR (C6D6):
δ 9.44 (s, 1H, bipy), 6.97 (m, 4H, bipy), 6.67 (m, 1H, bipy),
6.58 (m, 1H, bipy), 6.42 (s, 4H, ring CH), 6.29 (m, 1H, bipy),
6.21 (s, 1H, ring CH), 6.13 (s, 1H, ring CH), 6.08 (s, 1H, ring
CH), 5.63 (s, 2H, ring CH), 1.55 (s, 18H, (CH3)3C), 1.42 (s,
36H, (CH3)3C). 13C{1H} NMR (C6D6): δ 154.3, 152.4, 149.3,
146.7, 144.8, 139.6, 136.4, 124.9, 123.4, 121.3, 120.9, 112.7,
111.5, 111.4, 110.3, 110.2, 33.4, 33.1, 31.8, 31.7. IR (KBr,
Reaction of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2) with AgCl.
NMR Scale. AgCl (5.8 mg, 0.04 mmol) was added to a
J. Young NMR tube charged with [η5-1,3-(Me3C)2C5H3]2Th-
(bipy) (2; 14 mg, 0.02 mmol) and C6D6 (0.5 mL). The color of
the solution immediately changed from purple to colorless, and
resonances due to [η5-1,3-(Me3C)2C5H3]2ThCl2 (1) (1H NMR
(C6D6): δ 6.67 (t, J = 2.8 Hz, 2H, ring CH), 6.23 (d, J = 2.8 Hz,
4H, ring CH), 1.35 (s, 36H, (CH3)3C))19 along with those of
1
2,2′-bipyridine were observed by H NMR spectroscopy (100%
conversion).
Preparation of [η5-1,3-(Me3C)2C5H3]2ThBr2 (3). Method
A. AgBr (0.75 g, 4.0 mmol) was added to a toluene (20 mL) sol-
ution of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2; 1.11 g, 1.5 mmol)
5966 | Dalton Trans., 2012, 41, 5965–5973
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cm−1): ν 2961 (s), 2917 (s), 1560 (s), 1458 (s), 1260 (s), 1090
(s), 1021(s), 799 (s).
5 mL, colorless crystals of 10 were isolated when this solution
was kept at room temperature for one week. Yield: 0.65 g (62%)
(Found: C, 46.72; H, 6.07. C54H84S6Th2 requires C, 46.67; H,
Preparation of [η5-1,3-(Me3C)3C5H2]2Th(SePh)2 (6). Method
A. A benzene (10 mL) solution of PhSeSePh (0.47 g, 1.5 mmol)
was added to a benzene (20 mL) solution of [η5-1,3-
(Me3C)2C5H3]2Th(bipy) (2; 1.11 g, 1.5 mmol) with stirring at
room temperature. During the course of the reaction, the color of
the solution changed from purple to yellow. After the solution
was stirred at room temperature for 0.5 h, solvent was removed
and the yellow residue was extracted with n-hexane (10 mL × 3)
and filtered. The volume of the filtrate was reduced to 5 mL and
cooled to −20 °C, yielding yellow crystals of 6, which were iso-
lated by filtration. Yield: 1.10 g (82%) (Found: C, 50.72; H,
5.88. C38H52Se2Th requires C, 50.78; H, 5.83%). M.p.:
150–152 °C. 1H NMR (C6D6): δ 8.00 (m, 4H, phenyl), 7.08 (m,
4H, phenyl), 6.98 (m, 2H, phenyl), 6.18 (br s, 6H, ring CH),
1.33 (s, 36H, (CH3)3C). 13C{1H} NMR (C6D6): δ 152.0, 136.5,
135.2, 128.8, 125.5, 115.9, 113.4, 33.9, 32.2. IR (KBr, cm−1): ν
2962 (s), 2844 (m), 1571 (s), 1451 (s), 1392 (s), 1262 (s), 1091
(s), 1019 (s), 799 (s).
1
6.09%). M.p.: > 300 °C (dec.). H NMR (C6D6): δ 6.52 (br s,
2H, ring CH), 6.45 (br s, 2H, ring CH), 6.39 (br s, 4H, ring CH),
6.05 (br s, 2H, ring CH), 6.00 (br s, 2H, ring CH), 1.47 (s, 18H,
(CH3)3C), 1.44 (s, 18H, (CH3)3C), 1.37 (s, 18H, (CH3)3C), 1.34
(s, 18H, (CH3)3C). 13C{1H} NMR (C6D6): δ 264.3, 150.6,
150.0, 114.8, 113.4, 112.8, 111.2, 110.3, 34.7, 34.1, 33.5, 33.1,
32.6, 32.2, 31.8, 31.7. IR (KBr, cm−1): ν 2961 (s), 2856 (m),
1458 (m), 1354 (m), 1260 (s), 1090 (s), 1017 (s), 931 (s),
798 (s).
X-Ray crystallography
Single-crystal X-ray diffraction measurements were carried out
on a Bruker Smart APEX II CCD diffractometer at 110(2) K or
on a Rigaku Saturn CCD diffractometer at 113(2) K using graph-
ite monochromated Mο Kα radiation (λ = 0.71070 Å). An
empirical absorption correction was applied using the SADABS
program.21 All structures were solved by direct methods and
refined by full-matrix least squares on F2 using the SHELXL-97
program package.22 All the hydrogen atoms were geometrically
fixed using the riding model. Disordered solvents in the voids of
5 and 10 were modelled or removed by using the SQUEEZE
program.23 Crystal data and experimental data for 2–6 and 10 are
summarized in Table 1. Selected bond lengths and angles are
listed in Table 2.
Method B. NMR Scale. PhSeSePh (6 mg; 0.02 mmol) was
added to a J. Young NMR tube charged with [η5-1,3-
(Me3C)2C5H3]2Th(bipy) (2; 14 mg, 0.02 mmol) and C6D6
(0.5 mL). The color of the solution immediately changed from
purple to yellow, and resonances due to 6 along with those of
1
2,2′-bipyridine were observed by H NMR spectroscopy (100%
conversion).
Preparation of {[η5-1,3-(Me3C)2C5H3]2Th}(μ-S)2 (8). Method
A. A benzene (10 mL) solution of CS2 (0.11 g, 1.5 mmol) was
added to
a
benzene (20 mL) solution of [η5-1,3-
Results and discussion
(Me3C)2C5H3]2Th(bipy) (2; 1.11 g, 1.5 mmol) with stirring at
room temperature. After the solution was stirred at room temp-
erature overnight, solvent was removed and the residue was
extracted with n-hexane (10 mL × 3) and filtered. The volume of
the filtrate was reduced to 5 mL, colorless microcrystals of 8
were isolated when this solution was kept at room temperature
for two days. Yield: 0.77 g (83%) (Found: C, 50.38; H, 6.87.
C52H84S2Th2 requires C, 50.47; H, 6.84%). M.p.: > 300 °C
Synthesis of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2)
Treatment of an excess of KC8 with a 1 : 1 mixture of 2,2′-bipyr-
idine and [η5-1,3-(Me3C)3C5H2]2ThCl2 (1) in cyclohexane sol-
ution gives the purple bipy metallocene, [η5-1,3-
(Me3C)3C5H2]2Th(bipy) (2) in 79% yield (Scheme 1). Complex
2 is soluble in and readily recrystallized from an n-hexane sol-
ution. It is stable in dry nitrogen atmosphere, while it is very sen-
sitive to air and moisture. It has been characterized by various
spectroscopic techniques, elemental analysis and X-ray diffrac-
tion analysis. Complex 2 has narrow resonances with chemical
shifts in the range of 0–10 ppm and well-resolved coupling pat-
1
(dec.). H NMR (C6D6): δ 6.44 (br s, 2H, ring CH), 6.39 (br s,
8H, ring CH), 6.32 (br s, 2H, ring CH), 1.43 (s, 36H, (CH3)3C),
1.37 (s, 36H, (CH3)3C). 13C{1H} NMR (C6D6): δ 150.2, 148.0,
124.0, 123.6, 112.8, 111.2, 33.5, 33.1, 32.6, 32.2. IR (KBr,
cm−1): ν 2961 (s), 1534 (s), 1451 (s), 1388 (s), 1260 (s), 1089
(s), 1020 (s), 798 (s).
1
terns in its H NMR spectrum. The four resonances assigned to
the bipy ligand are significantly shifted to the high field in com-
parison with those in free bipy, and the ratio of bipy to Cp-
ligand is 1 : 2.24 The UV-vis spectrum shows two absorptions at
λmax = 528 nm (ε = 1.66 × 103 M−1 cm−1) and 375 nm (ε =
2.70 × 103 M−1 cm−1).24
Method B. NMR Scale. A C6D6 (0.3 mL) solution of CS2
(1.5 mg; 0.02 mmol) was added to a J. Young NMR tube
charged with [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2; 14 mg,
0.02 mmol) and C6D6 (0.2 mL). The color of the solution
immediately changed from purple to colorless, and resonances
due to 8 along with those of 2,2′-bipyridine were observed by
1H NMR spectroscopy (100% conversion).
The ORTEP representation of [η5-1,3-(Me3C)2C5H3]2Th(bipy)
(2) is shown in Fig. 1. The average Th–C(ring) distance is 2.837
(8) Å. The bulky Me3C-groups are nearly eclipsed with the Cp-
ligands pointing toward the front of the metallocene wedge. As
expected, the acceptance of electrons into the lowest unoccupied
molecular orbital of neutral bipy results in shortening of the C
(5)–C(6) bond and in flattening of the bipyridyl ligand. The
bending angle16 of the bipy in 2 is 139° and the C(5)–C(6) dis-
tance is 1.396(12) Å. These structural data are close to those
Preparation of {[η5-1,3-(Me3C)2C5H3]2Th}(μ-CS3)2 (10). A
benzene (20 mL) solution of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2;
1.11 g, 1.5 mmol) was added to a benzene (10 mL) solution of
CS2 (2.00 g, 26.3 mmol) with stirring at room temperature. After
the solution was stirred at room temperature overnight, the sol-
ution was filtered. The volume of the filtrate was reduced to
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Dalton Trans., 2012, 41, 5965–5973 | 5967

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Table 1 Crystal data and experimental parameters for compounds 2–6 and 10
Compound
2
3
4
5
6
10
Formula
Fw
Crystal system
Space group
a (Å)
b (Å)
c (Å)
C36H50N2Th
742.82
Monoclinic
P21/n
11.701(2)
17.020(2)
16.704(2)
90
97.88(1)
90
3295.4(7)
4
C26H42Br2Th
746.46
Monoclinic
P21/c
19.672(3)
16.500(2)
8.672(1)
90
98.20(1)
90
2786.2(6)
4
C26H42I2Th
840.44
Monoclinic
P21/c
19.495(2)
16.731(2)
8.895(1)
90
97.32(1)
90
2877.8(6)
4
C49H71F5N2Th2
1247.16
C38H52Se2Th
898.76
Monoclinic
Pc
12.033(2)
16.165(2)
19.461(3)
90
104.18(1)
90
3670.2(9)
4
C54H84S6Th2
1389.65
Triclinic
Triclinic
ˉ
ˉ
P1
P1
12.145(1)
13.749(1)
17.283(2)
102.73(1)
96.15(1)
91.44(1)
2795.3(5)
2
13.078(1)
14.466(1)
17.689(2)
82.53(1)
83.11(1)
70.64(1)
3119.9(4)
2
α (°)
β (°)
γ (°)
V (Å3)
Z
D
calc (g cm−3
)
1.497
4.550
1.780
8.230
1.940
7.337
1.482
5.359
1.627
6.069
1.479
4.992
μ(Mo Kα)calc (cm−1
Size (mm)
)
0.27 × 0.24 × 0.17 0.30 × 0.11 × 0.08 0.20 × 0.19 × 0.12 0.24 × 0.20 × 0.18 0.35 × 0.26 × 0.22 0.26 × 0.20 × 0.18
F(000)
2θ range (°)
No. of reflns, collected 19 214
1480
4.00 to 55.30
1432
4.18 to 50.50
14 047
1576
3.22 to 55.08
17 049
1208
3.38 to 55.86
35 795
1752
4.32 to 50.50
17 883
1896
2.32 to 67.50
54 435
No. of unique reflns
7514
(Rint = 0.0444)
5281
364
0.51, 0.37
5020
(Rint = 0.0750)
3568
279
0.56, 0.19
6580
(Rint = 0.0658)
4692
274
0.47, 0.32
13 245
(Rint = 0.0466)
9449
542
0.45, 0.36
9247
(Rint = 0.0408)
7973
762
0.35, 0.23
24 512
(Rint = 0.0384)
20 747
583
0.47, 0.36
No of obsd reflns
No of variables
Abscorr
(Tmax, Tmin
R
Rw
Rall
Gof
)
0.055
0.111
0.087
1.08
0.043
0.074
0.072
0.98
0.044
0.082
0.071
0.99
0.031
0.057
0.044
0.97
0.043
0.091
0.054
1.02
0.028
0.057
0.035
1.00
CCDC
860416
860417
860418
860419
860420
869908
found in [η5-1,2,4-(Me3C)3C5H2]2Th(bipy) with the bending
yield diselenido metallocene [η5-1,3-(Me3C)2C5H3]2Th(SePh)2
(6) in quantitative conversion (Scheme 1).
angle of 141° and a distance of 1.382(8) Å.16
Under similar reaction conditions, treatment of 2 with 1 equiv
of CS2 at room temperature irreversibly gives dimeric sulfido
complex {[η5-1,3-(Me3C)2C5H3]2Th}(μ-S)2 (8) in 83% yield
(Scheme 2). While reaction of 2 with an excess of CS2 at room
temperature forms the dimeric trithiocarbonate complex {[η5-
1,3-(Me3C)2C5H3]2Th}(μ-CS3)2 (10) in 62% yield (Scheme 2).
These observations suggest that 2 cleaves the CvS bond of CS2
to form the sulfido metallocene [η5-1,3-(Me3C)2C5H3]2ThS (7)
and carbon monosulfide CS. Monomeric sulfido 7 is unstable
and undergoes an irreversible dimerization or nucleophilic
addition resembling that of the thorium sulfido [η5-1,2,4-
(Me3C)3C5H2]2ThS.25 To the best of our knowledge, this is the
first example that a sulfido thorium complex was prepared by
reductive cleavage of CS2 with a low-valent thorium synthon.
Although carbon monosulfide is known to be very unstable,26
there have been instances where CS was trapped in situ during
reductive disproportionation processes of CS2.27 In contrast to
uranium μ-sulfido complex [((1-O-4-Me-6-AdC6H2-2-CH2)3N)-
U]2(μ-S),2g no reaction between thorium μ-sulfido 8 and CS2
occurs even heated at 65 °C for one week.
Reactivity of [η5-1,3-(Me3C)2C5H3]2Th(bipy) (2)
As expected, the bipy thorium complex 2 is very reactive. For
example, reaction of complex 2 with trityl chloride quantitatively
gives the chloride complex 1, along with the byproducts neutral
20
bipy and Gomberg’s dimer Ph3CCH(C2H2)2CvCPh2
(Scheme 1). The formation of Gomberg’s dimer, neutral bipy
and complex 1 implies that the free radical Ph3C˙ is formed by
the oxidation of 2 by Ph3C+. Likewise, the treatment of 2 with
silver chloride, bromide or iodide results in the halide metallo-
cenes [η5-1,3-(Me3C)2C5H3]2ThX2 (X = Cl (1), Br (3), I (4)) in
quantitative conversion (Scheme 1). The conversions are
measured by integration of the NMR resonances against an
internal standard. The pure halide complexes may be readily sep-
arated from free bipy, which is the only organic byproduct, by
recrystallization from an n-hexane solution, and the isolated pre-
parative scale yields are 90% for 3, and 93% for 4, respectively.
However, under similar reaction conditions, treatment of 2 with
2 equiv of silver fluoride does not give the desired difluoride
metallocene [η5-1,3-(Me3C)2C5H3]2ThF2, instead, a binuclear
thorium complex [η5-1,3-(Me3C)2C5H3]2Th(F)(μ-F)3Th[η5-1,3-
(Me3C)2C5H3](F)(bipy) (5) has been isolated in 64% yield
(Scheme 1), presumably due to the small size of the fluorine
anion and its strong nucleophilicity. Complex 2 cleaves Se–Se
bonds to give diselenido complexes. For example, reaction of 2
with 1 equiv of PhSeSePh results in Se–Se bond cleavage to
The complexes 3–6, 8 and 10 are stable in dry nitrogen atmos-
phere, but they are very moisture sensitive. They have been
characterized by various spectroscopic techniques and elemental
1
analyses. H and 13C NMR spectra indicate that complexes 3, 4,
6, 8 and 10 are symmetrical on the NMR spectroscopic time-
scale, which are consistent with their C2 or C2v-symmetric struc-
tures. Complexes 3–6 and 10 have been further confirmed by X-
ray diffraction analyses. The ORTEP diagrams of [η5-1,3-
5968 | Dalton Trans., 2012, 41, 5965–5973
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Table 2 Selected distances (Å) and angles (°) for compounds 2–6 and 10a
Compound C(Cp)–Th (ave) C(Cp)–Th (range) Cp(cent)–Th (ave) Th–X (ave)
Cp(cent)–Th–Cp(cent) X–Th–X
2
3
4
5
2.837(8)
2.789(8)
2.787(8)
2.771(8) to 2.882(7)
2.722(8) to 2.838(8)
2.719(7) to 2.848(8)
2.570(8)
2.512(8)
2.514(8)
2.326(7)
2.794(1)
3.035(1)
124.1(8)
127.3(8)
127.8(7)
74.1(2)
98.2(1)
102.4(1)
Th(1) 2.865(4) Th(1) 2.796(4) to 2.926(4) Th(1) 2.603 (4)
Th(2) 2.855(5) Th(2) 2.813(5) to 2.922(5) Th(2) 2.590(5)
Th(1)–F 2.378(2) Cp–Th(1)–Cp 112.8(2)
Th(2)–F 2.292(2)
Th(2)–N 2.677(4)
2.877(1)
2.988(1)
6
10
2.796(12)
2.837(2)
2.723(12) to 2.863(11)
2.770(2) to 2.902(2)
2.527(8)
2.587(2)
126.4(8)
117.5(1)
105.1(1)
S(1)–Th(1)–S(2) 59.4(1)
a Cp = cyclopentadienyl ring.
Scheme 1 Synthesis of complexes 2–6.
Fig. 1 Molecular structure of 2 (thermal ellipsoids drawn at the 35%
probability level).
(Me3C)2C5H3]2ThBr2 (3) and [η5-1,3-(Me3C)2C5H3]2ThI2 (4)
are shown in Fig. 2 and 3. The average Th–C(ring) distance is
2.789(8) Å for 3, and 2.787(8) Å for 4, respectively. In the solid
state, 3 and 4 have crystallographic C2 symmetry with staggered
Scheme 2 Synthesis of compounds 8 and 10.
Dalton Trans., 2012, 41, 5965–5973 | 5969
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Fig. 2 Molecular structure of 3 (thermal ellipsoids drawn at the 35%
probability level).
Fig. 4 Molecular structure of 5 (thermal ellipsoids drawn at the 35%
probability level).
Fig. 3 Molecular structure of 4 (thermal ellipsoids drawn at the 35%
probability level).
cyclopentadienyl ligands such as those in [η5-1,3-
(Me3C)2C5H3]2ThCl2.19 Complexes 3 and 4 have similar X–Th–
X angles (Table 2). In complex 3, the average Th–Br distance is
2.794(1) Å, which is close to those found in (η5-C5Me5)2ThBr2
(2.800(2) Å)28 and [η5-1,2,4-(Me3C)3C5H2]2ThBr2 (2.785(1)
Å).16 In complex 4, the average Th–I distance is 3.035(1) Å,
close to that (2.986(2) Å) found in (η5-C5Me5)2ThI2.29
Fig. 5 Molecular structure of 6 (thermal ellipsoids drawn at the 35%
probability level).
The molecular structure of 5 is shown in Fig. 4. Coordination
of three Cp-ligands and five fluorine atoms and one bipy group
around two Th4+ ions results in the formation of the dinuclear
atoms from a bipy group in a distorted-pentagonal-bipyramidal
geometry with an average Th–C(ring) distance of 2.855(5) Å.
The average Th(2)–F distance is 2.292(2) Å, slightly longer than
that (2.126(5) Å) found in [η5-1,2,4-(Me3C)3C5H2]2ThF2,16
while slightly shorter than that (2.378(2) Å) of Th(1)–F. The dis-
tance C(44)–C(45) is 1.467(6), which is comparable to those
found in [η5-1,2,4-(Me3C)3C5H2]Th(SePh)3(bipy) (1.484(9)
Å),16 and 2 (1.396(12) Å).
complex
[η5-1,3-(Me3C)2C5H3]2Th(F)(μ-F)3Th[η5-1,3-
(Me3C)2C5H3](F)(bipy). One Th4+ ion is η5-bond to two Cp-
rings and σ-bound to one terminal fluorine atom and three
doubly bridging fluorine atoms in a distorted-octahedral geome-
try with an average Th–C(ring) distance of 2.865(4) Å. The
angle of Cp–Th(1)–Cp is 112.8(2)°. The average Th(1)–F dis-
tance is 2.378(2) Å, and slightly longer than that (2.126(5) Å)
found in [η5-1,2,4-(Me3C)3C5H2]2ThF2.16 The other Th4+ ion is
η5-bond to one Cp-ring and σ-bound to one terminal fluorine
atom, three doubly bridging fluorine atoms and two nitrogen
The single-crystal X-ray diffraction analysis shows that there
are two molecules [η5-1,3-(Me3C)2C5H3]2Th(SePh)2 (6) in the
lattice. An ORTEP diagram of 6 is shown in Fig. 5, and shows
5970 | Dalton Trans., 2012, 41, 5965–5973
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[η5-1,2,4-(Me3C)3C5H2]2Th(bipy) with 1 equiv of PhSeSePh
gives a mixture of [η5-1,2,4-(Me3C)3C5H2]Th(SePh)3(bipy) and
[1,2,4-(Me3C)3C5H2]3Th(SePh),16 whereas 2 cleanly affords a
diselenido complex [η5-1,3-(Me3C)2C5H3]2Th(SePh)2 (6).
Further efforts are currently focused on the reactivity and the
exploration of the actinide bipy complexes towards other types
of transformations.
Acknowledgements
This work was supported by the National Natural Science Foun-
dation of China (Grant No. 20972018, 21074013, 21172022),
the Program for New Century Excellent Talents in University
(NCET-10-0253), the Fundamental Research Funds for the
Central Universities (China), and the Deutsche Forschungs-
gemeinschaft (DFG) through the Emmy-Noether program (WA
2513/2-1). We thank Professor Richard A. Andersen for helpful
discussions.
Fig. 6 Molecular structures of 10 (thermal ellipsoids drawn at the 35%
probability level).
Notes and references
crystallographic C2 symmetry with staggered cyclopentadienyl
ligands such as those in 3 and 4. The average Th–C(ring) dis-
tance is 2.796(12) Å, while the angle of Cp–Th(1)–Cp is 126.4
(8)°, and the angle of Se–Th–Se is 105.1(1)°. The average
Th–Se distance is 2.877(1) Å, which is slightly shorter than
that (2.938(8) Å) found in [η5-1,2,4-(Me3C)3C5H2]Th-
(SePh)3(bipy).16
1 (a) A. S. P. Frey, F. G. N. Cloke, M. P. Coles, L. Maron and T. Davin,
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The single-crystal X-ray diffraction analysis shows that in the
solid state 10 has crystallographic C2 symmetry, but the Th4+ ion
has a distorted octahedral coordination environment (Fig. 6)
with an average Th–C(ring) distance of 2.837(2) Å and the Cp-
(cent)–Th–Cp(cent) angle of 117.5(1)°. The orientation of the
cyclopentadienyl rings is nearly eclipsed. The small differences
in the C–S distances (0.006, 0.006 and 0.012 Å) suggest that the
2−
negative charge is delocalized over the CS3 fragment. The
average Th–S distance of 2.988(1) Å is comparable to those
found in {[η5-1,2,4-(Me3C)3C5H2]2Th(S)[(μ-S)2C]}6 (2.852(2)
Å),25 and [(Ph2PS)2C]2Th(DME) (2.931(2) Å).30
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M. Matson, P. E. Fanwick and S. C. Bart, Organometallics, 2011, 30,
5753–5762; (b) S. J. Kraft, U. J. Williams, S. R. Daly, E. J. Schelter, S.
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Conclusions
In conclusion, a new bipy thorium metallocene [η5-1,3-
(Me3C)2C5H3]2Th(bipy) (2) has been prepared and structurally
characterized. It cleanly reacts with oxidizing reagents such as
trityl chloride, silver halides and diphenyl diselenide, yielding
halido- and selenido-complexes. Furthermore, CS2 is activated
by a low-valent thorium synthon to give a sulfido thorium
complex.
In addition, replacing 1,2,4-tri-tert-butylcyclopentadienyl
ligand for 1,3-di-tert-butylcyclopentadienyl ligand, the different
reactivity patterns have been observed between bipy thorium
complexes [η5-1,2,4-(Me3C)3C5H2]2Th(bipy) and [η5-1,3-
(Me3C)2C5H3]2Th(bipy) (2). For example, reaction of [η5-1,2,4-
(Me3C)3C5H2]2Th(bipy) with 2 equiv of AgF cleanly yields the
difluoride complex [η5-1,2,4-(Me3C)3C5H2]2ThF2,16 while 2
affords
a
binuclear complex [η5-1,3-(Me3C)2C5H3]2Th(F)-
(μ-F)3Th[η5-1,3-(Me3C)2C5H3](F)(bipy) (5), which is most
likely due to the different steric demand of both ligands. Mixing
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