Carbon-fluorine bond cleavage in the preparation of osmium(III) and osmium(IV) fluorothiolate complexes. Fluorine by fluorine NMR-assignment and fluxional processes

Article abstract of DOI:10.1021/ic0619660

Reactions of OsO₄ with HSR (R = C₆F₅, C₆F₄H-4,) in refluxing ethanol afford [Os(SC ₆F₅)₃(SC₆F₄(SC ₆F₅)-2)] (1) and [Os(SC₆F₄H-4) ₃(SC₆F₃H-4-(SC₆F₄H-4)-2)] (2), which involve the rupture of C-F bonds. At room temperature, the compound [Os(SC₆F₅)₃(PMe₂Ph)₂] or [Os(SC₆F₅)₄(PMe₂Ph)] reacts with KOH(aq) in acetone, giving rise to [Os(SC₆F₅)(SC ₆F₄(SC₆F₄O-2)-2)(PMe ₂Ph)₂] (3), through a process involving the rupture of two C-F bonds, while the compound [Os(SC₆F₄H) ₄(PPh₃)] reacts with KOH(aq) in acetone to afford [Os(SC₆F₄H-4)₂(SC₆F ₃H-4-0-2)(PPh₃)] (4), which also implies a C-F bond cleavage. Single-crystal X-ray diffraction studies of 1, 2, and 4 indicate that these compounds include five-coordinated metal ions in essentially trigonal-bipyramidal geometries, whereas these studies on the paramagnetic compound 3 show a six-coordinated osmium center in a distorted octahedral geometry. ¹⁹F, ¹H, ³¹P{¹H}, and COSY ¹⁹F-¹⁹F NMR studies for the diamagnetic 1, 2, and 4 compounds, including variable-temperature ¹⁹F NMR experiments, showed that these molecules are fluxional. Some of the activation parameters for these dynamic processes have been determined.

Full text of DOI:10.1021/ic0619660

Inorg. Chem. 2007, 46, 4857−4867
Carbon−Fluorine Bond Cleavage in the Preparation of Osmium(III) and
Osmium(IV) Fluorothiolate Complexes. Fluorine by Fluorine
NMR-Assignment and Fluxional Processes
Maribel Arroyo,*,† Sylvain Berne`s,‡ Margarita Cero´n,† Vero´nica Cortina,† Consuelo Mendoza,† and
Hugo Torrens§
Centro de Qu´ımica del Instituto de Ciencias de la BUAP, Edificio 193 del Complejo de Ciencias,
Ciudad UniVersitaria, San Manuel, 72570 Puebla, Puebla, Mexico, DEP, Facultad de Ciencias
Qu´ımicas, UANL, Guerrero y Progreso S/N, Col. TreVin˜o 64570, Monterrey, N.L., Mexico, and
DiVisio´n de Estudios de Posgrado, Facultad de Qu´ımica, UNAM, Ciudad UniVersitaria,
04510 Me´xico D.F., Mexico
Received October 13, 2006
Reactions of OsO4 with HSR (R
) C6F5, C6F4H-4,) in refluxing ethanol afford [Os(SC6F5)3(SC6F4(SC6F5)-2)] (1)
and [Os(SC6F4H-4)3(SC6F3H-4-(SC6F4H-4)-2)] (2), which involve the rupture of C−F bonds. At room temperature,
the compound [Os(SC6F5)3(PMe2Ph)2] or [Os(SC6F5)4(PMe2Ph)] reacts with KOH(aq) in acetone, giving rise to
[Os(SC6F5)(SC6F4(SC6F4O-2)-2)(PMe2Ph)2] (3), through a process involving the rupture of two C−F bonds, while
the compound [Os(SC6F4H)4(PPh3)] reacts with KOH(aq) in acetone to afford [Os(SC6F4H-4)2(SC6F3H-4-O-2)(PPh3)]
(4), which also implies a C F bond cleavage. Single-crystal X-ray diffraction studies of 1, 2, and 4 indicate that
−
these compounds include five-coordinated metal ions in essentially trigonal-bipyramidal geometries, whereas these
studies on the paramagnetic compound 3 show a six-coordinated osmium center in a distorted octahedral geometry.
1
19F, H, 31P
{
1H
}
, and COSY 19F
−
19F NMR studies for the diamagnetic 1, 2, and 4 compounds, including variable-
temperature 19F NMR experiments, showed that these molecules are fluxional. Some of the activation parameters
for these dynamic processes have been determined.
Introduction
homogeneous catalysts to modify hydrocarbons in several
industrial processes, such as olefin hydrogenations, hydro-
formylations, and polymerizations. Analogous processes do
not presently exist for fluorocarbons, although it has become
evident that interaction of fluorocarbons with metal centers
may ultimately lead to the cleavage of the robust C-F bonds.
The C-F bond activation of fluorinated hydrocarbons by
transition-metal centers has been an area of intense study
during the last years,2-20 and catalytic systems have been
The chemical inertness and high thermal stability of
fluorocarbons have made them useful in a variety of
exceptional applications ranging from frying pan coating to
artificial blood.1 This chemical inertness makes the chemistry
of fluorocarbons an area of research that has attracted the
attention of inorganic and organometallic chemists, and new
routes to transform these bonds are currently the subject of
many investigations. The chemical and intellectual challenges
of C-F bond activation rival those of C-H activation in
hydrocarbons. Transition-metal compounds are employed as
(2) Asplund, M. C.; Johnson, A. M.; Jakeman, J. A. J. Phys. Chem. B
2006, 110 (1), 20-24.
(3) Maron, L.; Werkema, E. L.; Perrin, L.; Eisenstein, O.; Andersen, R.
A. J. Am. Chem. Soc. 2005, 127, 279-292.
* To whom correspondence should be addressed. E-mail:
slarroyo@siu.buap.mx.
(4) Hughes, R. P.; Laritchev, R. B.; Zakharov, L. N.; Rheingold, A. L. J.
Am. Chem. Soc. 2005, 127, 6325-6334.
† Centro de Qu´ımica del Instituto de Ciencias de la BUAP, Edificio 193
del Complejo de Ciencias, Ciudad Universitaria.
(5) Burling, S.; Elliott, P. I. P.; Jasim, N. A.; Lindup, R. J.; Mckenna, J.;
Perutz, R. N.; Archibald, S. J.; Whitwood, A. C. J. Chem. Soc., Dalton
Trans. 2005, 3686-3695.
‡ Facultad de Ciencias Qu´ımicas, UANL.
§ Divisio´n de Estudios de Posgrado, Facultad de Qu´ımica, UNAM,
Ciudad Universitaria.
(6) Piglosiewicz, I. M.; Kraft, S.; Beckhaus, R.; Haase, D.; Saak, W. Eur.
J. Inorg. Chem. 2005, 938-945.
(1) (a) May, G. Chem. Br. 1997, 34-36. (b) Clark, L. C.; Gollan, F.
Science 1966, 152 (3730), 1755-1756. (c) Wall, L. A. Fluoropoly-
mers; Wiley-Interscience: New York, 1972; Vol. XXXV.
(7) Villanueva, L.; Arroyo, M.; Berne`s, S.; Torrens, H. Chem. Commun.
2004, 1942-1943.
10.1021/ic0619660 CCC: $37.00
Published on Web 05/16/2007
© 2007 American Chemical Society
Inorganic Chemistry, Vol. 46, No. 12, 2007 4857

Arroyo et al.
developed.21-23 The subject has been reviewed.24-29
Previously, we reported on the synthesis of [Os(SR)3-
(PMe2Ph)2] (R ) C6F4H-4, C6F5).30,31 The X-ray diffraction
and osmium tetroxide, were from Aldrich Chemical Co. and used
without further purification. Complexes [Os(SC6F5)3(PMe2Ph)2],30,31
[Os(SC6F5)4(PMe2Ph)],34 and [Os(SC6F4H)4(PPh3)]34 were prepared
as published. The products were separated by passage through a
silica gel chromatographic column with a hexanes-CH2Cl2 solution
as the eluent.
32
structure determination of the compound where R ) C6F5
showed a C-F-Os interaction in the solid state. The
interaction of an o-F of one of the SC6F5 ligands with the
metal creates an S-F chelate ligand, resulting in six
coordination in an approximately octahedral arrangement.
We found that thermolysis of [Os(SR)3(PMe2Ph)2] in reflux-
ing toluene causes a substantial rearrangement-oxidative
reaction, giving a mixture of products that involves phosphine
dissociation, cleavage of an o-C-F bond at a thiolate ligand,
and transfer of a sulfur atom along with oxidation of the
metal center.32,33 We have now found that the formation of
complexes 1-4 also involves the cleavage of C-F bonds.
Melting points were obtained on a Fisher-Johns melting point
apparatus.
IR spectra were recorded over the 4000-400 cm-1 range on a
Magna-Nicolet 750 Fourier transform IR spectrometer as KBr
pellets. Data are expressed in wavenumbers (cm-1) with relative
intensities (vs ) very strong, s ) strong, m ) medium, and w )
weak).
1H, 19F, and COSY 19F-19F NMR spectra were recorded on a
Varian Mercury VX400 spectrometer operating at 400 and 376
MHz, while 31P{1H} NMR spectra were recorded on a Varian
Mercury VX300 spectrometer operating at 121 MHz. Chemical
shifts are relative to tetramethylsilane [δ ) 0 (1H)], CCl3F [δ ) 0
(19F)], and H3PO4 [δ ) 0 (31P)] using C6D5CD3 as the solvent.
The free energies of activation ∆Gq were calculated from
variable-temperature (VT) 19F NMR data using both the line-shape
analysis and the Eyring equation for compounds 1 and 4, and for
each compound, both results are practically equal within experi-
mental error. The line-shape analysis is not feasible for compound
2, in which overlapping bands are present at several temperatures.
Therefore, to have systematic results, all of the ∆Gq values reported
in this paper have been calculated with the Eyring equation,
estimating the rate constant at the coalescence temperature on the
basis of the chemical shift difference at low temperature.
Positive-ion fast atom bombardment mass spectrometry (FAB+-
MS) spectra were recorded on a Jeol JMS-SX102A mass spec-
trometer operated at an accelerating voltage of 10 kV. Samples
were desorbed from a 3-nitrobenzyl alcohol matrix using 3 keV
xenon atoms. Mass measurements in FAB are performed at a
resolution of 3000 using magnetic field scans and the matrix ions
as the reference material.
Experimental Section
Materials and Methods. All reactions were carried out under
argon using conventional Schlenk-tube techniques. Thin layer
chromatography (Merck; 5-7.5 cm2 Kiesegel 60 F254) was used to
monitor the progress of the reactions under study with hexanes-
CH2Cl2 (4:1) as the eluent. The starting materials, thiols, phosphines,
(8) Clot, E.; Me´gret, C.; Kraft, B. M.; Eisenstein, O.; Jones, W. D. J.
Am. Chem. Soc. 2004, 126, 5647-5653.
(9) Bellabarba, R. M.; Nieuwenhuyzen, M.; Saunders, G. C. Organome-
tallics 2003, 22, 1802-1810.
(10) Braun, T.; Rothfeld, S.; Schorlemer, V.; Stammler, A.; Stammler, H.-
G. Inorg. Chem. Commun. 2003, 6, 752-755.
(11) Ferrando-Miguel, G.; Ge´rard, H.; Eisenstein, O.; Caulton, K. G. Inorg.
Chem. 2002, 41 (24), 6440-6449.
(12) Sladek, M. I.; Braun, T.; Neumann, B.; Stammler, H.-G. J. Chem.
Soc., Dalton Trans. 2002, 297-299.
(13) Kraft, B. M.; Jones, W. D. J. Organomet. Chem. 2002, 658, 132-
140.
(14) Braun, T.; Cronin, L.; Higgitt, C. L.; McGrady, J. E.; Perutz, R. N.;
Reinhold, M. New J. Chem. 2001, 25 (1), 19-21.
(15) Barrio, P.; Castarlenas, R.; Esteruelas, M. A.; Lledo´s, A.; Maseras,
F.; On˜ate, E.; Toma`s, J. Organometallics 2001, 20, 442-452.
(16) Huang, D.; Koren, P. R.; Folting, K.; Davidson, E. R.; Caulton, K. G.
J. Am. Chem. Soc. 2000, 122, 8916-8931.
Elemental analyses were determined by Galbraith Laboratories
Inc.
(17) Whittlesey, M. K.; Perutz, R. N.; Moore, M. H. Chem. Commun. 1996,
787-788.
Preparations. [Os(SC6F5)3(SC6F4(SC6F5)-2)] (1). HSC6F5 (1.6
mL, 12 mmol) was dissolved in ethanol (60 mL), then OsO4 (0.5
g, 2 mmol) was added, and the colorless mixture immediately turned
black. The stirred mixture was refluxed for 3.5 h. After this time,
the solvent was removed under vacuum, and the residue was
purified by column chromatography (silica gel, hexane-CH2Cl2,
4.5:0.5). Compound 1 was obtained as green crystals (0.420 g, 18%)
by slow evaporation of the eluent. Anal. Calcd for C30F24OsS5: C,
30.88; S, 13.74. Found: C, 31.43; S, 13.65. Mp: 120 °C (dec). IR
(KBr, cm-1): 1506 (vs), 1488 (vs), 1462 (s), 1394 (w), 1092 (s),
1046 (w), 981 (vs), 854 (m). 19F NMR (C6D5CD3, -50 °C): δ
(18) Hofmann, P.; Unfried, G. Chem. Ber. 1992, 125, 659-661.
(19) Crespo, M.; Mart´ınez, M.; Sales, J. J. Chem. Soc., Chem. Commun.
1992, 822-823.
(20) Blum, O.; Frolow, F.; Milstein, D. J. Chem. Soc., Chem. Commun.
1991, 258-259.
(21) Aizenberg, M.; Milstein, D. Science 1994, 265, 359-361.
(22) Aizenberg, M.; Milstein, D. J. Am. Chem. Soc. 1995, 117, 8674-
8675.
(23) Kuhl, S.; Schneider, R.; Fort, Y. AdV. Synth. Catal. 2003, 345 (3),
341-344.
(24) Torrens, H. Coord. Chem. ReV. 2005, 249, 1957-1985.
(25) Richmond, T. G. Angew. Chem., Int. Ed. 2000, 39, 3241-3244.
(26) Richmond, T. G. In Topics in Organometallic Chemistry; Murai, S.,
Ed.; Springer: New York, 1999; Vol. 3, pp 243-269.
(27) Burdenuic, J.; Jedlicka, B.; Crabtree, R. H. Chem. Ber. 1997, 130,
145-154.
3
4
ring a, δ -128.8 (dd, 1F, C6F4, JF-F ) 23 Hz, JF-F ) 9 Hz),
-132.8 (m, 1F, C6F4), -142.7 (m, 1F, C6F4), -151.4 (t, 1F, C6F4,
3JF-F ) 22 Hz); ring b, δ -128.0 (d, 1Fo, C6F5, 3JFo-Fm ) 19 Hz),
-135.2 (br s, 1Fo, C6F5), -140.3 (t, 1Fp, C6F5, 3JFp-Fm ) 22 Hz),
(28) Saunders, G. C. Angew. Chem., Int. Ed. Engl. 1996, 35 (22), 2615-
2617.
3
(29) Kiplinger, J. L.; Osterberg, C. E.; Richmond, T. G. Chem. ReV. 1994,
-155.4 (m, 1Fm, C6F5), -156.9 (t, 1Fm, C6F5, JF-F ) 21 Hz);
ring c, δ -131.9 (d, 1Fo, C6F5, 3JFo-Fm ) 23 Hz), -132.2 (d, 1Fo,
94, 373-411.
(30) Catala´, R. M.; Cruz-Garritz, D.; Hills, A.; Hughes, D. L.; Richards,
R. L.; Sosa, P.; Torrens, H. J. Chem. Soc., Chem. Commun. 1987,
261-262.
3
3
C6F5, JFo-Fm ) 25 Hz), -148.1 (t, 1Fp, C6F5, JFp-Fm ) 21 Hz),
-160.2 (m, 1Fm, C6F5), -160.8 (m, 1Fm, C6F5); ring d, δ -130.7
(d, 1Fo, C6F5, 3JFo-Fm ) 23 Hz), -132.5 (d, 1Fo, C6F5, 3JFo-Fm
)
(31) Catala´, R. M.; Cruz-Garritz, D.; Sosa, P.; Terreros, P.; Torrens, H.;
Hills, A.; Hughes, D. L.; Richards, R. L. J. Organomet. Chem. 1989,
359, 219-232.
25 Hz), -148.6 (t, 1Fp, C6F5, 3JFp-Fm ) 21 Hz), -159.3 (m, 1Fm,
(32) Arroyo, M.; Berne`s, S.; Brianso´, J. L.; Mayoral, E.; Richards, R. L.;
Rius, J.; Torrens, H. Inorg. Chem. Commun. 1998, 1, 273-276.
(33) Arroyo, M.; Berne`s, S.; Brianso´, J. L.; Mayoral, E.; Richards, R. L.;
Rius, J.; Torrens, H. J. Organomet. Chem. 2000, 599, 170-177.
(34) Arroyo, M.; Chamizo, J. A.; Hughes, D. L.; Richards, R. L.; Roma´n,
P.; Sosa, P.; Torrens, H. J. Chem. Soc., Dalton Trans. 1994, 1819-
1824.
4858 Inorganic Chemistry, Vol. 46, No. 12, 2007

Osmium(III) and Osmium(IV) Fluorothiolate Complexes
Table 1. X-ray Parameters
complex
1
2
3
4
chem formula
C
30F24OsS5‚0.5H2O
C30H5F19OsS5
1076.84
C
34H22F13OOsP2S3
C
36H18F11OOsPS3
fw
1175.81
P21/n
1041.84
992.85
P21/c
space group
P21/c
P21/n
a/Å
14.8936(15)
18.3106(17)
9.2362(11)
20.0791(19)
90.00
8.416(2)
10.3807(11)
b/Å
16.227(2)
19.096(4)
22.572(4)
90.00
22.029(3)
c/Å
15.9492(14)
15.8319(17)
R/deg
90.00
90.00
â/deg
95.561(6)
97.707(8)
90.00
3365.1(6)
4
4.230
R1 ) 5.66, wR2 ) 13.28
R1 ) 9.20, wR2 ) 15.10
2.126
8940/496
23(1)
96.036(15)
90.00
3607.4(12)
4
3.894
R1 ) 3.70, wR2 ) 6.63
R1 ) 6.87, wR2 ) 7.52
1.918
6335/491
21(1)
100.694(9)
γ/deg
90.00
90.00
V/Å3
3836.3(7)
3557.5(7)
Z
4
4
µ/mm-1
3.739
3.894
R indices [I > 2 σ(I)]a
R1 ) 4.23, wR2 ) 10.39
R1 ) 6.19, wR2 ) 11.51
2.036
R1 ) 3.37, wR2 ) 6.00%
R1 ) 5.94, wR2 ) 6.74
1.854
R indices (all data)a
D
calcd/g‚cm-3
data/param
8767/557
25(1)
6274/479
23(1)
T/°C
a R1 ) (∑||Fo| - |Fc||)/∑|Fo|; wR2 ) [(∑w(Fo - Fc )2)/∑w(Fo )2]1/2
.
2
2
2
C6F5), -159.8 (m, 1Fm, C6F5); ring e, δ -131.3 (d, 2Fo, C6F5,
3JFo-Fm ) 24 Hz), -154.3 (t, 1Fp, C6F5, 3JFp-Fm ) 21 Hz), -162.0
(m, 2Fm, C6F5). FAB+-MS {m/z (%) [fragment]}: 1168 (62) [M+],
969 (100) [M+ - SC6F5], 802 (29) [M+ - SC6F5 - C6F5], 770
(45) [M+ - 2(SC6F5)], 603 (76) [M+ - 2(SC6F5) - C6F5].
FAB+-MS {m/z (%) [fragment]}: 1043 (48) [M+], 905 (79) [M+
- PMe2Ph], 844 (80) [M+ - SC6F5], 706 (8) [M+ - SC6F5 -
PMe2Ph].
Compound 3 was also obtained in a similar yield by an analogous
procedure from the green complex [Os(SC6F5)4(PMe2Ph)].
[Os(SC6F4H-4)3(SC6F3H-4-(SC6F4H-4)-2)] (2). HSC6F4H-4 (1.6
mL, 12 mmol) was dissolved in ethanol (50 mL), and OsO4 (0.5 g,
2 mmol) was added. The mixture rapidly turned black. The stirred
mixture was refluxed for 3.5 h. After this time, a solid was filtered,
which was washed with cold ethanol and hexane to give 2 as a
microcrystalline green powder. An additional crop of 2 was
recovered by column chromatography of the filtered solution (silica
gel, hexanes-CH2Cl2, 4.5:0.5), and green crystals (0.450 g, 21%)
were obtained by slow evaporation of the eluent. Anal. Calcd for
C30H5F19OsS5: C, 33.46; H, 0.47; S, 14.89. Found: C, 33.54; H,
0.58; S, 15.48. Mp: 212 °C (dec). IR (KBr, cm-1): 1494 (vs),
[Os(SC6F4H-4)2(SC6F3H-4-(O-2))(PPh3)] (4). The green com-
plex [Os(SC6F4H-4)4(PPh3)] (0.2354 g, 0.2 mmol) was dissolved
in acetone (15 mL). To this stirred solution was added 2 mL of an
aqueous 0.20 M KOH solution. The mixture rapidly turned reddish
brown. The mixture was stirred at room temperature for 36 h, and
its color slowly changed to dark green. After this time, the solvent
was distilled off under vacuum. The solid product was purified
through a chromatographic column (silica gel, hexane-CH2Cl2,
4:1). Compound 4 was obtained as green crystals (0.024 g, 12%)
by slow evaporation of the eluent. Anal. Calcd for C36H18F11-
OOsPS3: C, 43.55; H, 1.83; S, 9.69. Found: 42.71; H, 1.65; S,
9.28. Mp: 170 °C (dec). IR (KBr, cm-1): 1491 (vs), 1470 (sh),
1372 (w), 1230 (m), 1176 (w), 916 (s), 847 (w), 712 (w). 1H NMR
(C6D5CD3, RT): isomer A, δ 7.27 (m, 6.0H, PPh3, full integral )
6.6), 6.67 (m, 9.0H, PPh3, full integral ) 9.9), 6.12 (m, 1H,
o-OSC6F3H), 5.90 (br s, 2.0H, SC6F4H, full integral ) 2.2); isomer
B, δ 7.27 (m, 0.6H, PPh3, full integral ) 6.6), 6.67 (m, 0.9H, PPh3,
full integral ) 9.9), 5.90 (br s, 0.2H, SC6F4H, full integral ) 2.2),
5.62 (m, 0.1H, o-OSC6F3H). 19F NMR (C6D5CD3, RT): isomer A,
thiolates, δ -134.0 (s, 4.0Fo, SC6F4H, full integral ) 4.4), -140.4
(br s, 2.0Fm, SC6F4H, full integral ) 2.2), -141.3 (br s, 2.0Fm,
SC6F4H, full integral ) 2.2); isomer A, thiolate-phenoxide, δ
-141.7 (m, 1F, o-OSC6F3H), -143.7 (m, 1F, o-OSC6F3H), -152.3
(ddd, 1F4, o-OSC6F3H, 3JF4-F3 ) 23 Hz, 4JF4-F6 ) 10 Hz, 3JF4-H5
) 3 Hz); isomer B, thiolates, δ -134.0 (s, 0.4Fo, SC6F4H, full
integral ) 4.4), -140.4 (br s, 0.2Fm, SC6F4H, full integral ) 2.2),
-141.3 (br s, 0.2Fm, SC6F4H, full integral ) 2.2); isomer B,
1
1374 (m), 1231 (m), 918 (s), 850 (m), 716 (m). H NMR (C6D5-
3
4
CD3, RT): δ 5.94 (tt, 1H, 1SC6F4H, JHp-Fm ) 9.6 Hz, JHp-Fo
)
3
4
7.2 Hz), 5.87 (tt, 1H, 1SC6F4H, JHp-Fm ) 9.6 Hz, JHp-Fo ) 8.0
Hz), 5.82 (tt, 1H, 1SC6F4H, JHp-Fm ) 9.6 Hz, JHp-Fo ) 7.2 Hz),
3
4
3
4
5.60 (tt, 1H, 1SC6F4H, JHp-Fm ) 9.6 Hz, JHp-Fo ) 7.2 Hz), 5.32
(m, 1H, o-OSC6F3H, 3JHp-Fm ) 9.6 Hz, 3JHp-Fm ) 9.6 Hz, 4JHp-Fo
) 7.3 Hz). 19F NMR (C6D5CD3, -50 °C): ring a, δ -109.7 (m,
3
1F, C6F3H), -124.3 (dt, 1F, C6F3H, JF-F ) 23 Hz), -132.8 (m,
1F, C6F3H); ring b, δ -129.1 (m, 1Fo, C6F4H), -134.1 (br m, 2F,
C6F4H), -134.9 (m, 1Fm, C6F4H); ring c, δ -131.4 (br s, 1Fo,
C6F4H), -132.7 (m, 1Fo, C6F4H), -138.0 (m, 1Fm, C6F4H, full
integral ) 2), -138.2 (m, 1Fm, C6F4H); ring d, δ -130.8 (br s,
1Fo, C6F4H), -133.1 (m, 1Fo, C6F4H), -136.7 (m, 1Fm, C6F4H),
-138.0 (m, 1Fm, C6F4H, full integral ) 2); ring e, δ -131.0 (m,
2Fo, C6F4H), -138.9 (m, 2Fm, C6F4H). FAB+-MS {m/z (%)
[fragment]}: 1078 (19) [M+], 897 (30) [M+ - SC6F4H], 748 (8)
[M+ - SC6F4H - C6F4H], 716 (9) [M+ - 2(SC6F4H)], 567 (18)
[M+ - 2(SC6F4H) - C6F4H].
4
thiolate-phenoxide, δ -118.3 (pt, 0.1F, o-OSC6F3H, JF-F ) 11
3
3
Hz), -138.0 (dd, 0.1F5, o-OSC6F3H, JF5-F6 ) 20 Hz, JF5-H4
)
[Os(SC6F5)(SC6F4(SC6F4O-2)-2)(PMe2Ph)2] (3). The purple
complex [Os(SC6F5)3(PMe2Ph)2] (0.2127 g, 0.2 mmol) was dis-
solved in acetone (15 mL). To this stirred solution was added 2
mL of an aqueous 0.20 M KOH solution. The mixture rapidly turned
brown. The mixture was stirred at room temperature for 24 h, and
its color turned dark blue. The solvent was removed under vacuum,
and the residue was purified by column chromatography (silica gel,
hexane-CH2Cl2, 3:2). Compound 3 was obtained as blue crystals
(0.052 g, 25%) by slow evaporation of the eluent. Anal. Calcd for
C34H22F13OOsP2S3: C, 39.20; H, 2.13; S, 9.23. Found: 40.12; H,
2.26; S, 9.10. Mp: 234 °C. IR (KBr, cm-1): 1509 (vs), 1493 (vs),
1470 (vs), 1086 (s), 973 (m), 944 (w), 912 (w), 853 (w), 746 (w).
10 Hz), -170.2 (m, 0.1F, o-OSC6F3H). 31P{1H} NMR (C6D5CD3,
RT): isomer A, δ 3.1 (s, 1P, PPh3); isomer B, δ 3.4 (s, 0.1P, PPh3).
FAB+-MS {m/z (%) [fragment]}: 994 (94) [M+], 917 (5) [M+
-
Ph], 813 (10) [M+ - SC6F4H], 663 (18) [M+ - SC6F4H - C6F4H
- H], 631 (5) [M+ - SC6F4H - C6F4H - H - S].
X-ray Diffraction Data. Air-stable single crystals of complexes
1-4 were obtained by slow evaporation of solutions as described
above. Pertinent crystal data and other crystallographic parameters
are listed in Table 1. Diffraction data were collected at 294-298
K on a Bruker P4 diffractometer using graphite-monochromated
Mo KR radiation (λ ) 0.710 73 Å) and standard procedures.35
Inorganic Chemistry, Vol. 46, No. 12, 2007 4859

Arroyo et al.
Table 2. Selected Bond Lengths (Å) and Angles (deg) for 1
Os1-S2
Os1-S1
S1-C7
2.1976(15)
2.3739(13)
1.773(6)
Os1-S3
Os1-S5
S2-C12
S5-C25
2.2034(15)
2.4020(14)
1.786(6)
Os1-S4
S1-C1
S3-C13
2.2343(15)
1.778(6)
1.764(5)
S4-C19
1.766(6)
1.769(6)
S2-Os1-S3
S3-Os1-S4
S3-Os1-S1
S2-Os1-S5
S4-Os1-S5
118.73(6)
116.11(6)
94.96(5)
85.66(6)
93.08(5)
S2-Os1-S4
S2-Os1-S1
S4-Os1-S1
S3-Os1-S5
S1-Os1-S5
125.14(6)
88.30(5)
88.75(5)
89.71(5)
173.64(5)
Os1-S1-C1
Os1-S1-C7
Os1-S2-C12
Os1-S3-C13
Os1-S4-C19
Os1-S5-C25
114.21(19)
103.83(19)
106.8(2)
111.44(18)
110.48(19)
109.83(18)
Table 3. Selected Bond Lengths (Å) and Angles (deg) for 2
Os1-S2
Os1-S1
S1-C7
2.1965(17)
2.3829(16)
1.773(7)
Os1-S3
Os1-S5
S2-C12
S5-C25
2.2139(19)
2.401(2)
1.767(7)
1.752(8)
Os1-S4
S1-C1
S3-C13
2.2186(18)
1.779(6)
1.791(8)
S4-C19
1.779(7)
S2-Os1-S3
S3-Os1-S4
S3-Os1-S1
S2-Os1-S5
S4-Os1-S5
118.00(8)
120.38(8)
94.95(7)
91.31(7)
94.19(7)
S2-Os1-S4
S2-Os1-S1
S4-Os1-S1
S3-Os1-S5
S1-Os1-S5
121.61(7)
88.43(6)
87.82(6)
83.23(8)
177.79(7)
Os1-S1-C1
Os1-S1-C7
Os1-S2-C12
Os1-S3-C13
Os1-S4-C19
Os1-S5-C25
113.7(2)
103.2(2)
106.8(2)
109.7(3)
112.8(2)
109.2(3)
Table 4. Selected Bond Lengths (Å) and Angles (deg) for 3
Os1-O42
Os1-P2
Os1-S5
2.099(4)
2.3414(16)
2.3659(16)
Os1-S3
Os1-P1
Os1-S4
2.3247(16)
2.3559(17)
2.4035(15)
S3-C31
S4-C36
S4-C41
S5-C51
1.762(6)
1.799(6)
1.795(6)
1.771(6)
O42-Os1-S3
S3-Os1-P2
S3-Os1-P1
O42-Os1-S5
P2-Os1-S5
O42-Os1-S4
P2-Os1-S4
S5-Os1-S4
90.70(12)
92.82(6)
87.57(6)
93.26(12)
88.26(6)
82.43(11)
168.20(6)
92.40(5)
O42-Os1-P2
O42-Os1-P1
P2-Os1-P1
S3-Os1-S5
P1-Os1-S5
S3-Os1-S4
P1-Os1-S4
85.77(12)
178.21(13)
94.74(6)
175.96(6)
88.46(6)
87.34(5)
97.05(6)
Os1-S3-C31
Os1-S4-C36
Os1-S4-C41
Os1-S5-C51
105.4(2)
103.24(19)
97.3(2)
109.2(2)
Table 5. Selected Bond Lengths (Å) and Angles (deg) for 4
Os1-O20
Os1-S3
Os-P1
2.084(3)
2.2132(15)
2.3333(12)
Os1-S1
Os1-S2
2.1909(13)
2.2213(14)
S1-C19
S2-C25
S3-C31
1.758(5)
1.794(5)
1.791(5)
O20-Os1-S1
S1-Os1-S3
S1-Os1-S2
O20-Os1-P1
S3-Os1-P1
85.11(9)
118.16(6)
120.36(6)
176.54(9)
89.31(5)
O20-Os1-S3
O20-Os1-S2
S3-Os1-S2
S1-Os1-P1
S2-Os1-P1
92.44(11)
89.88(10)
121.42(6)
91.43(4)
91.76(5)
Os1-S1-C19
Os1-S2-C25
Os1-S3-C31
101.25(18)
107.22(18)
108.06(19)
Structures were solved and refined36 on the basis of absorption-
corrected data (ψ scans). Structures were refined without restraints
or constraints for non-hydrogen atoms. Hydrogen atoms were placed
in idealized positions and refined using a riding approximation with
constrained bond lengths and fixed isotropic displacement param-
eters. In the case of 1, disordered water molecules were found in
the crystal structure, probably arising from ethanol used as the
solvent for the synthesis. However, it is unclear why water was
included in the case of 1 and not for other complexes. One molecule
(O1) lies in a general position, while the other (O2) lies on an
inversion center. Site occupation factors were first roughly refined
and eventually fixed to 1/4 in the last refinement cycles. Complete
crystallographic data were deposited in CIF format. Structure factors
are available upon request to the authors.
Results and Discussion
We have previously reported the C-F bond cleavage, by
thermolysis reactions in refluxing toluene, of the osmium(III)
compounds [Os(SR)3(PMe2Ph)2] (R ) C6F4H-4 or C6F5). We
have now found related C-F bond ruptures during the
formation of the osmium(IV) compounds 1 and 2 from OsO4
and an excess of HSR in refluxing ethanol. As discussed
below, the reaction products have been identified according
to Schemes 1 and 2.
On the other hand, the room-temperature reaction between
the osmium(III) compound [Os(SC6F5)3(PMe2Ph)2] in ac-
etone and an aqueous solution of KOH gives rise to 3, the
formation of which requires the cleavage of two C-F bonds.
Compound 3 is also obtained by the analogous reaction with
the osmium(IV) compound [Os(SC6F5)4(PMe2Ph)], as shown
in Scheme 3.
Selected geometric parameters for 1-4 are listed in Tables 2-5,
respectively.
(35) XSCAnS Users Manual, release 2.21; Siemens Analytical X-ray
Instruments Inc.: Madison, WI, 1996.
(36) Sheldrick, G. M. SHELXTL-plus, release 5.10; Siemens Analytical
X-ray Instruments Inc.: Madison, WI, 1998.
However, the room-temperature reaction of the os-
mium(IV) compound [Os(SC6F4H)4(PPh3)] in acetone with
4860 Inorganic Chemistry, Vol. 46, No. 12, 2007

Osmium(III) and Osmium(IV) Fluorothiolate Complexes
Scheme 1
Scheme 2
Figure 1. Structure of 1 showing thermal displacement parameters at the
30% probability level. Water is omitted for clarity.
The FAB-MS spectrum of complex 3 shows the parent
ion (m/z ) 1043, 48%) from which losses of PMe2Ph and
SC6F5 (m/z ) 905, 79%, m/z ) 844, 80%) are observed.
The subsequent losses of SC6F5 or PMe2Ph, respectively, give
rise to the ion [Os(SC6F4(SC6F4O)-2)(PMe2Ph)]+ (m/z ) 706,
8%). The paramagnetism of this d5 osmium(III) compound
precluded structural NMR studies in solution, but fortunately
single crystals of 3 were obtained and its X-ray structure is
shown in Figure 3, from which it is evident that the formation
of compound 3 implies the rupture of two C-F bonds from
the original C6F5 rings belonging to the starting material, in
addition to the incorporation of an oxygen atom and the
formation of a C-S bond.
The FAB-MS spectrum of complex 4 shows the parent
ion (m/z ) 994, 92%) from which successive losses of
SC6F4H, C6H2F4, and S (m/z ) 813, 10%, m/z ) 663, 18%,
m/z ) 631, 5%) are observed. The C-F bond cleavage in
the formation of 4 is also confirmed by the X-ray structure,
which is shown in Figure 4.
an aqueous solution of KOH gives rise to 4, the formation
of which also requires the cleavage of a C-F bond (Scheme
4).
Complexes 1-4 were isolated by column chromatography
as crystalline and air-stable solids. These osmium(IV) (1, 2,
and 4) and osmium(III) (3) compounds were characterized
by elemental analyses, FAB+-MS spectrometry, and spec-
troscopy. The FAB-MS spectra of compounds 1 and 2 show
the corresponding parent ions (1, m/z ) 1168, 62%; 2, m/z
) 1078, 19%) from which successive losses of two SC6F5
(or SC6F4H) and one C6F5 (or C6F4H) (1, m/z ) 969, 100%,
m/z ) 770, 45%, m/z ) 603, 76%; 2, m/z ) 897, 30%, m/z
) 716, 9%, m/z ) 567, 18%) are observed. The loss of C6F5
(or C6F4H) from the ion [Os(SC6F5)2(SC6F4(SC6F5)-2)]+ (or
[Os(SC6F4H)2(SC6F3H(SC6F4H)-2)]+) is also observed (1, m/z
) 802, 29%; 2, m/z ) 748, 8%). The C-F bond cleavage
in the formation of 1 and 2 is confirmed by X-ray structure
determinations, which are shown in Figures 1 and 2,
respectively.
The X-ray-characterized complexes are mononuclear spe-
cies: three of them (1, 2, and 4) with five-coordinated metal
Scheme 3
Inorganic Chemistry, Vol. 46, No. 12, 2007 4861

Arroyo et al.
Figure 2. Structure of 2 showing thermal displacement parameters at the
30% probability level for non-hydrogen atoms. Hydrogen atom labels are
omitted for clarity.
Figure 4. Structure of 4 showing thermal displacement parameters at the
30% probability level for non-hydrogen atoms. Hydrogen atom labels are
omitted for clarity.
The structures of 1 and 2 consist of discrete essentially
trigonal-bipyramidal molecules with a persulfurated coor-
dination sphere. These two structures show the same ar-
rangement and conformation of the ligands. Two of the three
-
equatorial positions are occupied by thiolate ligands (SC6F5 ,
1, or SC6F4H-, 2) oriented trans with respect to the trigonal
plane, “one-up, one-down”. The third thiolate ligand (SC6F5-,
1, or SC6F4H-, 2) is coordinated in an axial position. The
chelating thiolate-thioether ligand [(SC6F4(SC6F5))-, 1, or
(SC6F3H(SC6F4H))-, 2] occupies an axial position [through
S1 (thioether)] and an equatorial one [through S2 (thiolate)].
This arrangement is analogous to that observed in the related
complex [Ru(SC6HMe4-2,3,5,6)3(SCHMeCH2SC6HMe4-2,3,
5,6)].37 For obvious steric reasons, the pentafluorophenyl 1
or tetrafluorophenyl 2 ring at S1ax is staggered with respect
to the S2-Os1-S4 angle (dihedral angle between phenyl
and Os1/S2/S4 planes: 42.30(2)° in 1 and 37.5(2)° in 2,
corresponding to a gauche conformation). As a consequence,
the S2-Os1-S4 angle is the largest of the three Seq-Os-
Seq angles in each of these molecules. As might be
expected,38 the axial Os-Sthiolate bond length [2.4020(14) Å
for 1 or 2.401(2) Å for 2] is longer than the equatorial Os-
Sthiolate bond lengths [2.1976(15)-2.2343(15) Å for 1 or
2.1965(17)-2.2186(18) Å for 2]. The axial Os-Sthioether
distance [2.3739(13) Å for 1 or 2.3829(16) Å for 2] is slightly
shorter than the axial Os-Sthiolate distance.
Figure 3. Structure of 3 showing thermal displacement parameters at the
30% probability level for non-hydrogen atoms. Hydrogen atom labels are
omitted for clarity.
Scheme 4
The X-ray diffraction study of 3 reveals a distorted
octahedral geometry around the osmium center with a thio-
late-thioether-phenoxide ligand, (SC6F4(SC6F4O-2)-2)2-,
where the S3thiolate, S4thioether, and O42phenoxide atoms occupy
three facial positions. A PMe2Ph ligand is coordinated trans
to the O42phenoxide atom, and a second PMe2Ph ligand is trans
to the S4thioether atom. The coordination sphere is completed
-
ions in essentially trigonal-bipyramidal geometry, whereas
compound 3 has a six-coordinated metal center in a distorted
octahedral geometry.
by a SC6F5 ligand, trans to the S3thiolate atom. The Os-
S4thioether distance [2.4035(15) Å], trans to a PMe2Ph ligand,
is longer than the mutually trans Os-S3thiolate and Os-S5thiolate
4862 Inorganic Chemistry, Vol. 46, No. 12, 2007

Osmium(III) and Osmium(IV) Fluorothiolate Complexes
The molecular structure of 4 shows an essentially trigonal-
bipyramidal coordination geometry with an axial PPh3 ligand
and two equatorial SC6F4H- groups. The chelating thiolate-
phenoxide ligand, o-OSC6F3H2-, occupies both remaining
axial (through O20) and equatorial (through S1) positions.
Hence, the ligand o-OSC6F3H2- forms a five-membered
chelate ring with the osmium atom, and the plane defined
by the Os/S1/O20/C6F3H group is a bisector of the S2-Os-
S3 angle, minimizing sterical hindrance in the molecule. The
structure of 4 resembles that of [Os(SC6F5)2(o-S2C6F4)(PMe2-
Ph)].33 There are no significant differences in equatorial
distances Os-Sthiolate between these two compounds. How-
ever, the Os-P distance in 4, 2.3333(12) Å, is shorter than
the corresponding distance in [Os(SC6F5)2(o-S2C6F4)(PMe2-
Ph)],33 2.374(4) Å, which reflects the larger trans influence
of a thiolate ligand compared with a phenoxide ligand.
Figure 5. Drawing of 1 (X ) F) or 2 (X ) H) showing the different
phenyl rings. Although the NMR absorptions are linked to the aromatic
rings a-e, except for the rigid ring a, no definitive b-e correspondence
can be established.
distances [2.3247(16) and 2.3659(16) Å, respectively], which
reflects the greater trans influence of the phosphine ligands
compared to the thiolate ligands. These Os-Sthiolate distances
are similar to those, also mutually arranged trans, in the
related osmium(III) complex [Os(SC6F4H-4)2(S2CSC6F4H-
4)(PMe2Ph)2]39 [2.3459(14) and 2.3476(14) Å]. In 3, both
Os-P bond lengths are similar [2.3559(17) and 2.3414(16)
Å] and compare well with the corresponding Os-P distances
in [Os(SC6F4H-4)2(S2CSC6F4H-4)(PMe2Ph)2]39 [2.3706(13)
and 2.3422(13) Å].
For both Os-O bonds trans to phosphine in complex 3,
OsIII-Ophenoxide, and complex 4, OsIV-Ophenoxide, the bond
lenghts are similar, a fact that has been attributed to a
compensating balance between electrostatic attraction and
effective covalent bonding.
The perfluorinated compound 1 was analyzed in solution
by 19F NMR spectroscopy. If the C6F5 rings are not restricted
to rotate about their C-S bonds and assuming that the solid-
Figure 6. COSY 19F-19F NMR spectrum of 1 at -50 °C.
Inorganic Chemistry, Vol. 46, No. 12, 2007 4863

Arroyo et al.
Figure 7. 19F NMR spectra of 1 at -50, -20, +24, and +60 °C. The letter labels identify the signals that correspond to the same fluorinated ring,
including the relative integrals.
state structure of 1 is retained in solution, one would expect
a 16-absorption spectrum: four groups of three different
resonances for the o-, p-, and m-fluorine atoms, at low,
medium, and high fields, respectively (relative intensities in
each group: 2:1:2),40 corresponding to four distinct C6F5
fragments, and a further group of four different absorptions
(intensities 1:1:1:1) for the C6F4 group. In contrast, the 19F
NMR spectra at room temperature exhibit 19 signals. When
the 19F NMR spectra were recorded at -50 °C, 22 different
resonances were found, 2 of them with relative integrals of
2 and the other 20 with relative integrals of 1, giving a total
of 24 fluorine atoms as in the X-ray diffraction structure
(Figures 1 and 5). The COSY 19F-19F NMR spectrum at
-50 °C confirms five subspectra corresponding to four C6F5
and one C6F4 groups (Figure 6). Three of the C6F5 subspectra
correspond to AA′BCC′ spin systems (intensities 1:1:1:1:
1), one corresponds to an A2BC2 spin system (intensities 2:1:
2), and the C6F4 subspectrum exhibits an ABCD spin pattern
(intensities 1:1:1:1). This spectrum at -50 °C is consistent
with three C6F5 rings subject to restricted rotations about
their C-S bonds, one C6F5 ring with free C-S bond rotation,
and the additional rigid C6F4 ring, consistent with its chelating
character.
The 19F NMR spectra were measured every 10 or 5 °C,
from -80 to +80 °C, whereas COSY 19F-19F NMR spectra
were determined at -50, -20, 24, and 60 °C in order to
follow the evolution and confirm the assignation of the
absorptions corresponding to each subspectrum. Figure 7
shows the corresponding one-dimensional spectra at these
temperatures, including their relative integrals.
The spectra at high temperature (ca. 80 °C) are consistent
with the presence of three C6F5 groups (c, d, and e) with
free C-S bond rotation. As the temperature is lowered, the
signals ortho (2) and meta (2) from the c-C6F5 group collapse,
each one giving rise to a pair of signals (1:1 and 1:1) that
reach their maximum definition at ca. -50 °C. In sequence,
two more absorptions, ortho (2) and meta (2) from the d-C6F5
group, follow a similar behavior and collapse as the
temperature is decreased, suggesting that the c-C6F5 group
finds an increased restriction to rotate around its C-S bond.
The b-C6F5 group is also restricted to rotate, in this case
within the full range of registered temperatures (always 1:1:
1:1:1), being the most restricted C6F5 group to rotate. A
fourth group of C6F5 signals (e) remains unchanged (sys-
tematically 2:1:2), suggesting that this group shows no
restrictions to undergo C-S bond rotation along the full
4864 Inorganic Chemistry, Vol. 46, No. 12, 2007

Osmium(III) and Osmium(IV) Fluorothiolate Complexes
Figure 8. VT 19F NMR spectra of 1 on the meta region of the c-e groups.
1
Figure 9. Room-temperature H NMR spectrum of 2.
range of studied temperatures. For obvious reasons, the C6F4
ring (a) of the chelating ligand is always impeded to rotate
(always 1:1:1:1).
resonances corresponding to the five nonequivalent hydrogen
atoms as found in the solid-state structure (Figures 2 and
5): four signals, triplet of triplets, attributed to the para
hydrogens of four nonequivalent C6F4H-4 rings and, at higher
field, one multiplet corresponding to the C6F3H ring.
From detailed analyses of the VT 19F NMR spectra in the
region of meta absorptions (Figure 8), the free energies of
activation for C-S bond rotation of both C6F5 groups (c and
d) have been calculated as ∆Gq ) 62 ( 2 kJ‚mol-1 for the
group c (coalescence temperature ) 47 °C) and ∆Gq ) 58
( 2 kJ‚mol-1 for the group d (coalescence temperature )
30 °C).
2 affords a set of 19F and COSY 19F-19F NMR spectra
equivalent to that discussed above for compound 1. VT 19
F
NMR experiments also show that compounds 1 and 2 share
a similar fluxional behavior. For compound 2, from analyses
of the VT 19F NMR data in the region of meta absoptions,
we have calculated the free energy of activation for the C-S
bond rotation process in the corresponding d group as ∆Gq
) 59 ( 2 kJ‚mol-1 (coalescence temperature ) 45 °C).
However, some overlap of signals precludes the correspond-
ing calculation for the c group.
Room-temperature 1H NMR spectra of compound 2
(Figure 9) show, in the aromatic region, five equally intense
(37) Matsukawa, S.; Kuwata, S.; Hidai, M. Inorg. Chem. Commun. 1998,
1, 368-371.
(38) Rossi, A. R.; Hoffmann, R. Inorg. Chem. 1975, 14, 365-374.
(39) Arroyo, M.; Berne`s, S.; Cero´n, J.; Rius, J.; Torrens, H. Inorg. Chem.
2004, 43, 986-992.
It is important to notice that NMR spectroscopy is unable
to distinguish between each of the fluorinated aryl substit-
(40) Bertra´n, A.; Garc´ıa, J.; Martin, E.; Sosa, P.; Torrens, H. ReV. Soc.
Qu´ım. Me´x. 1993, 37 (4), 185-191; Chem. Abstr. 1993, 122, 329084j.
Inorganic Chemistry, Vol. 46, No. 12, 2007 4865

Arroyo et al.
Figure 10. VT 19F NMR of 4: signals a from SC6F4H (both isomers), signals b from o-OSC6F3H (isomer A), and signals c from o-OSC6F3H (isomer B).
uents in each of the compounds 1 and 2 except when they
are part of a rigid chelating ligand as found in (SC6F4(SC6F5)-
2), compound 1, and (SC6F3H-4-(SC6F4H-4)-2), compound
2. Therefore, the NMR absorptions are linked to aromatic
rings a, b, c, d, and e on each compound but, except for the
rigid rings a, no definitive assignment can be done.
cally equal values within experimental error (below). Except
for small variations due to subtle changes in the magnetic
couplings, the subspectra arising from the thiolate-phenox-
ide fragment remain essentially unchanged through the full
range of temperatures. An additional subspectrum (c signals;
ABC spin system, intensities 0.1:0.1:0.1), which also remains
unchanged along the full range of temperatures, suggests that
4 exists as the pair of structural isomers shown as follows:
VT 19F NMR spectra of compound 4 show this molecule
to be also fluxional. At high temperature (ca. 80 °C), the
19F NMR spectra of compound 4 (Figure 10) exhibit two
signals (a; A2B2 spin system, intensities 4.4:4.4) correspond-
ing to the o- and m-fluorine nuclei of two magnetically
equivalent (SC6F4H-4)- ligands and three additional absorp-
tions (b; intensities 1:1:1) arising from each of the three
fluorine nuclei at the (OSC6F3H)2- moiety (ABC spin
system). As the temperature is lowered, the meta signal from
the SC6F4H-4 groups broadens, decreases in height, and
eventually collapses (below 30 °C), giving rise to a pair of
signals with the same intensity. This pair reaches its full
definition at ca. -50 °C without further changes. The ortho
signal from these SC6F4H-4 groups remains as a single band
until ca. 10 °C, although its relative height began to decrease
from ca. 50 °C and, at ca. 5 °C, also collapses, giving rise
to a pair of signals with the same intensity (the scale in Figure
10 does not allow one to appreciate this collapse at 5 °C,
but the corresponding expansions does allow it). This pair
also reaches its maximum definition at ca. -50 °C without
further changes. The different coalescence points of the ortho
(10 °C) and meta (30 °C) signals from the SC6F4H groups
of 4 are explained considering the different proximity of the
chemical shifts between both ortho or both meta signals.
However, as expected, free energies of activation ∆Gq
calculated from ortho and meta parameters result in practi-
Both isomers differ in the relative position of the hydrogen
atom at the thiolate-phenoxide ring either attached to
carbon-5 or carbon-4 relative to the axial oxygen or sulfur
atom. 19F NMR spectra indicate that both isomers are present
in relative amounts of ca. 10:1. Two-dimensional 19F-19F
NMR experiments confirmed two subspectra for the SC6F4H
and OSC6F3H groups of the more abundant isomer.
The 31P{1H} NMR spectra of 4 exhibit two singlets with
relative integrals of ca. 10:1 corresponding to each one of
the isomers.
1H NMR spectra of 4 are also consistent with the presence
of these two isomers in a ratio of ca. 10:1. Thus, in addition
to the signals corresponding to the protons of the C6H5 rings
from the PPh3 axial ligand, and only one signal of the SC6F4H
4866 Inorganic Chemistry, Vol. 46, No. 12, 2007

Osmium(III) and Osmium(IV) Fluorothiolate Complexes
groups for both isomers, two signals attributed to the
o-OSC6F3H fragment of each one of the isomers with relative
integrals of ca. 10:1 are also present. Thus, it is evident from
thiolate-phenoxide ligand. Nucleophilic displacement of
o-fluorine by OH- from a C6F5 ring bound to phosphorus
had previously been observed in the formation of trans-[Pt-
(CH3)(o-OC6F4PPh2)(PPh2(C6F5))],41,42 prepared from trans-
[Pt(CH3)(THF)(PPh2(C6F5))2] and KOH.
1
the H and 19F NMR spectra that the SC6F4H groups from
isomers A and B are magnetically equivalent, while the
corresponding OSC6F3H groups are not. The fluxional
behavior of this compound can be attributed, as in the
previous cases, to a hindered rotation around the S-C6F4H
bonds on this geometry. We have calculated the correspond-
ing free energies of activation for 4 from the analyses of
VT 19F NMR spectra in the regions of both ortho and meta
(SC6F4H-4) absorptions, resulting in practically the same
values within experimental error, 55 ( 2 and 57 ( 2
kJ‚mol-1, respectively.
The free energies of activation for the rotations about the
S-C6F5 or S-C6F4H bonds, calculated to be 62 ( 2 kJ‚mol-1
(group c) and 58 ( 2 kJ‚mol-1 (group d) [compound 1], 59
( 2 kJ‚mol-1 (group d) [compound 2], and 56 ( 3 kJ‚mol-1
[compound 4], are close to the corresponding free energies
of activation in [Os(SC6F5)2(o-S2C6F4)(PMe2Ph)]33 and [Os-
(SC6F4H)2(o-S2C6F3H)(PMe2Ph)]33 (59 ( 4 kJ‚mol-1) and
are also close to those found for P-C6F5 bond rotations (55
( 2 kJ‚mol-1).43
The formation of 1 and 2 from OsO4 and HSC6F5 or
HSC6F4H involves cleavage of an o-C-F bond at a SC6F5
or SC6F4H group, respectively. The mechanism of these
reactions has still not been established, but because the
products 1 and 2 bear (SC6F4(SC6F5)-2)- or (SC6F3H-4-
(SC6F4H-4)-2)- ligands, respectively, one of the original SR
moieties had to be involved in a reaction such that an
o-fluorine atom is replaced by a sulfur atom.
Acknowledgment. We are grateful to CONACYT (Grant
27915E) and VIEP (Grant 03/NAT/06-G) for financial
support. S.B. acknowledges BUAP for the use of diffraction
facilities.
Supporting Information Available: X-ray crystallographic
files, in CIF format, for structures 1-4. This material is available
free of charge via the Internet at http://pubs.acs.org.
On the other hand, the formation of 3 from [Os-
(SC6F5)3(PMe2Ph)2] or [Os(SC6F5)4(PMe2Ph)] and KOH
involves two ruptures of o-C-F bonds at SC6F5 groups,
whereas an o-fluorine atom is replaced by oxygen, with the
formation of new C-O and Os-O bonds. The formation of
4 from [Os(SC6F4H-4)4(PPh3)] and KOH implies the cleavage
of an o-C-F bond at a SC6F4H group and its simultaneous
replacement by an oxygen atom with the formation of a
IC0619660
(41) Park, S.; Pontier-Johnson, M.; Roundhill, D. M. Inorg. Chem. 1990,
29, 2689-2697.
(42) Park, S.; Pontier-Johnson, M.; Roundhill, D. M. J. Am. Chem. Soc.
1989, 111, 3101-3103.
(43) Atherton, M. J.; Fawcett, J.; Holloway, J. H.; Hope, E. G.; Karac¸ar,
A.; Russell, D. R.; Saunders, G. C. J. Chem. Soc., Dalton Trans. 1996,
3215-3220.
Inorganic Chemistry, Vol. 46, No. 12, 2007 4867