Protonation Reactions of trans-M(H)(SPh)(dppe)2 (M = Ru, Os) to Give Thiol and Dihydrogen Complexes. X-ray Crystal Structure Determination of trans-Ru(H)(SPh)(dppe)2 and trans-[Os(H)(O2)(dppe)2](O3SCF3)

Article abstract of DOI:10.1021/ic971050g

The compounds trans-M(H)(SPh)(dppe)₂ (M = Ru (1Ru), Os (1Os); dppe = 1,2-bis(diphenylphosphino)ethane) are synthesized by reaction of NaSPh with trans-[Ru(H₂)(H)(dppe)₂]BPh₄ or with trans-Os(H)(Br)(dppe)₂ in THF under Ar. They are characterized by ¹H and ³¹P NMR, IR, FAB mass spectroscopy, elemental analyses, and cyclic voltammetry. The crystal structure determination of 1Ru verifies the trans, octahedral geometry, which is distorted by ring-ring interactions. The thiophenoxide ligand is coordinated to the metal in a bent configuration, with the phenyl ring sandwiched between two phenyl rings of one of the dppe ligands. The reaction of complexes 1 with 1 equiv of HBF₄·Et₂O leads to the formation of the very reactive hydride thiol complexes trans-[M(H)-(HSPh)(dppe)₂]BF₄ (M = Ru (2Ru), Os (2Os)). Analogous complexes to 1Os and 2Os with SC₆H₄-4-F instead of SPh are also described. In all cases there is no evidence for the existence of the tautomeric dihydrogen complex trans-[M(H₂)(SAr)(dppe)₂]⁺. In the presence of excess acid the diprotonated complex trans-[Os(H₂)(HSPh)-(dppe)₂](BF₄)₂ (3Os) is formed at 233 K where the T₁(min) of the H₂ ligand at 400 MHz is ～34 ms so that 0.98 ≤ d_HH ≤ 1.24 A?. Under certain conditions the labile PhSH ligand of 3Os is substituted by water to give trans-[Os(H₂)(OH₂)(dppe)₂](BF₄) ₂ (4Os). The thiol complexes 2 react rapidly with H₂(g) to give the complexes trans[M(H₂)H(dppe)₂]BF₄ (5Ru, 5Os). Complexes 3Os and 4Os also react with H₂ to give 5Os. N₂ and O₂ (1 atm) displace the thiol in 2Os in CH₂Cl₂ to produce trans-[Os(H)(L)(dppe)₂]⁺ (L = η¹-N₂ (6Os), η²-O₂, (7Os)). trans-[Os(H)(O₂)(dppe)₂]OTf·3C₆H ₆ is characterized by X-ray diffraction.

Full text of DOI:10.1021/ic971050g

Inorg. Chem. 1998, 37, 1555-1562
1555
Protonation Reactions of trans-M(H)(SPh)(dppe)2 (M ) Ru, Os) To Give Thiol and
Dihydrogen Complexes. X-ray Crystal Structure Determination of trans-Ru(H)(SPh)(dppe)2
and trans-[Os(H)(O2)(dppe)2](O3SCF3)
Tanya Y. Bartucz, Adina Golombek, Alan J. Lough, Patricia A. Maltby, Robert H. Morris,*
Ravindranath Ramachandran, and Marcel Schlaf
Department of Chemistry, University of Toronto, Toronto, ON M5S 3H6, Canada
ReceiVed August 19, 1997
The compounds trans-M(H)(SPh)(dppe)2 (M ) Ru (1Ru), Os (1Os); dppe ) 1,2-bis(diphenylphosphino)ethane)
are synthesized by reaction of NaSPh with trans-[Ru(H2)(H)(dppe)2]BPh4 or with trans-Os(H)(Br)(dppe)2 in THF
1
under Ar. They are characterized by H and 31P NMR, IR, FAB mass spectroscopy, elemental analyses, and
cyclic voltammetry. The crystal structure determination of 1Ru verifies the trans, octahedral geometry, which is
distorted by ring-ring interactions. The thiophenoxide ligand is coordinated to the metal in a bent configuration,
with the phenyl ring sandwiched between two phenyl rings of one of the dppe ligands. The reaction of complexes
1 with 1 equiv of HBF4‚Et2O leads to the formation of the very reactive hydride thiol complexes trans-[M(H)-
(HSPh)(dppe)2]BF4 (M ) Ru (2Ru), Os (2Os)). Analogous complexes to 1Os and 2Os with SC6H4-4-F instead
of SPh are also described. In all cases there is no evidence for the existence of the tautomeric dihydrogen complex
trans-[M(H2)(SAr)(dppe)2]+. In the presence of excess acid the diprotonated complex trans-[Os(H2)(HSPh)-
(dppe)2](BF4)2 (3Os) is formed at 233 K where the T1(min) of the H2 ligand at 400 MHz is ∼34 ms so that 0.98
e dHH e 1.24 Å. Under certain conditions the labile PhSH ligand of 3Os is substituted by water to give trans-
[Os(H2)(OH2)(dppe)2](BF4)2 (4Os). The thiol complexes 2 react rapidly with H2(g) to give the complexes trans-
[M(H2)H(dppe)2]BF4 (5Ru, 5Os). Complexes 3Os and 4Os also react with H2 to give 5Os. N2 and O2 (1 atm)
displace the thiol in 2Os in CH2Cl2 to produce trans-[Os(H)(L)(dppe)2]+ (L ) η1-N2 (6Os), η2-O2 (7Os)). trans-
[Os(H)(O2)(dppe)2]OTf‚3C6H6 is characterized by X-ray diffraction.
Introduction
Scheme 1
A question of fundamental importance is as follows: “Where
does the proton go when a Bro¨nsted acid is added to a complex
containing both a thiolate and hydride ligand?” Four possible
answers are represented by the structures of the products in
Scheme 1 and are listed here with literature precedents: (A)
on the sulfur to give a thiol complex;1-3 (B) on the sulfur-
metal bond to give an η2-thiol ligand;4 (C) on the metal-hydride
bond to give an η2-dihydrogen ligand;2,5,6 (D) on the metal to
give a dihydride.
In one series of complexes [M(H2)(CO)(L)(PPh3)2]+ and
[M(H)(CO)(LH)(PPh3)2]+ (M ) Ru, Os; L ) pyridine-2-
thiolate, quinoline-8-thiolate), some of us were able to observe
an equilibrium between dihydrogen thiolate (C) and hydride
thiol (A) tautomeric forms (eq 1).2
are very acidic. For example the quinoline-8-thiol ligand in
the series just mentioned has a pKa on the aqueous scale of
about -1.2 The benzenethiol ligand in the complex [Fe(C5H5)-
(CO)2(SHPh)]+ also has a pKa value of less than zero,7 whereas
free PhSH has an aqueous pKa value of 6.4.8 We expected that
the complexes trans-M(H)(SPh)(dppe)2 (M ) Ru (1Ru), Os
(1Os)) would protonate at the M-H bond to produce dihydrogen
complexes trans-[M(H2)(SPh)(dppe)2]+ by analogy to the
complexes trans-M(H)(Cl)(dppe)2 which do give dihydrogen
complexes trans-[M(H2)(Cl)(dppe)2]+ (8Ru, 8Os) with pKa
[M](H )(SR) [M](H)(HSR)
a
(1)
2
A
C
For one to observe such an equilibrium, the dihydrogen
complex C must be very acidic because coordinated thiol ligands
(1) Wander, S. A.; Reibenspies, J. H.; Kim, J. S.; Darensbourg, M. Y.
Inorg. Chem. 1994, 33, 1421-1426.
(2) (a) Schlaf, M.; Lough, A. J.; Morris, R. H. Organometallics 1996,
15, 5, 4423-4436. (b) Schlaf, M.; Morris, R. H. J. Chem. Soc., Chem.
Commun. 1995, 625-626.
(5) Schlaf, M.; Lough, A. J.; Morris, R. H. Organometallics 1993, 12, 2,
3808-3809.
(3) Sellman, D.; Rackelmann, G. H.; Heinemann, F. W. Chem. Eur. J.
1997, 3, 2071-2080.
(6) Albeniz, M. J.; Buil, M. L.; Esteruelas, M. A.; Lopez, A. M.; Oro, L.
A.; Zeier, B. Organometallics 1994, 13, 3746-3748.
(4) Darensbourg, M. Y.; Liaw, W. F.; Riordan, C. G. J. Am. Chem. Soc.
1989, 111, 8051-2.
(7) Treichel, P. M.; Rosenhein, L. D. Inorg. Chem. 1981, 20, 942-944.
(8) Jencks, W. P.; Salvesen, K. J. Am. Chem. Soc. 1971, 93, 4433-4435.
S0020-1669(97)01050-1 CCC: $15.00 © 1998 American Chemical Society
Published on Web 03/13/1998

1556 Inorganic Chemistry, Vol. 37, No. 7, 1998
Bartucz et al.
values of 6.0 and 7.4, for M ) Ru and Os, respectively.9,10
However we report here that the expected dihydrogen complexes
are not observed because the thiol hydride isomers trans-[M(H)-
(HSPh)(dppe)2]BF4 (M ) Ru (2Ru), Os (2Os)) are more stable.
In related work Wander et al. have reported that the anion
[Fe(SPh)(CO)2(P(OPh)3)2]- protonates at the metal to give Fe-
(H)(SPh)(CO)2(P(OPh)3)2, which in turn protonates at the sulfur
to give the very acidic complex [Fe(H)(HSPh)(CO)2(P(OPh)3)2]+.1
referenced externally but reported relative to CFCl3. Elemental analyses
were performed by Guelph Chemical Laboratories Ltd.
A PAR model 273 potentiostat was used for cyclic voltammetry
studies. The electrochemical cell contained a platinum working
electrode, a tungsten secondary electrode, and a silver wire reference
electrode in a Luggin capillary. The cyclic voltammograms were
collected in dichloromethane containing 0.2 M n-Bu4NPF6 as the
supporting electrolyte. Reported potentials are referenced to ferrocene,
which was added to these solutions.
In keeping with the principle that dicationic dihydrogen
complexes are unusually stable,11,12 we also report the observa-
tion of the very acidic, dicationic dihydrogen thiol complex
trans-[Os(H2)(HSPh)(dppe)2](BF4)2 (3Os). The related complex
trans-[Os(H2)(SMe2)(NH2CH2CH2NH2)2](BF4)2 has previously
Preparation of trans-Ru(H)(SPh)(dppe)2 (1Ru). RuCl2(dppe)2
(0.650 g, 0.671 mmol) and NaBPh4 (1.020 g, 4.4 equiv) were stirred
together in 10 mL of THF under an atmosphere of H2 open to a mercury
bubbler for 3 h. The initially deep red solution gradually lightened to
become a pale yellow solution after 20 min. In a separate flask, (PhS)2
(0.112 g, 0.513 mmol) and NaBH4 (0.042 g, 2.2 equiv) were stirred
together in 5 mL of THF and 5 mL of EtOH under an Ar atmosphere.
Upon initial addition of the NaBH4 to the solution, bubbles of H2 were
observed to rise from the solution. This solution was stirred for 5 days.
The ruthenium-containing solution was filtered through Celite directly
into the thiolate-containing solution, to give a deep yellow solution.
The solvent was evaporated and the resulting yellow solids washed
three times with MeOH, giving a bright yellow solid. Slow diffusion
of ethanol into a saturated benzene solution of the complex produced
analytically pure yellow crystals, suitable for X-ray crystallography
(0.45 g, 80% yield). IR: 1918 cm-1 (m, νRuH). 1H NMR (C6D6, 200
MHz): 7.5-6.3 (m br, 45H, Ph), 2.6 (m, 4H, CH2), 1.8 (m, 4H, CH2),
-15.3 ppm (quint, 1H, 2JHP ) 19.1 Hz, RuH). 31P NMR (C6D6): 62.3
ppm (s). Anal. Calcd for C58H54P4RuS: C, 69.11; H, 5.40. Found:
C, 69.40; H, 5.41.
1
been characterized by H NMR spectroscopy.13
Experimental Section
General Methods. Unless otherwise noted, air was excluded from
the reactions by use of Schlenk techniques or Vacuum Atmospheres
gloveboxes. In general, reactions were performed under argon, as was
the purification of most of the charged complexes. The neutral
complexes and [Os(H)(N2)(dppe)2]+ were worked up under N2. Solid
[Os(H)(O2)(dppe)2]+ (7Os) was generally handled in air.
Solvents were dried over the following reagents and distilled under
dinitrogen: CaSO4 for acetone, calcium hydride for dichloromethane,
Linde type 4 Å molecular sieves for CD2Cl2, sodium for toluene,
sodium/benzophenone ketyl for Et2O, THF, benzene, and hexanes,
and Mg(OH)x(OR)2-x for alcohols. Except where noted, deuterated
solvents were used as received from Cambridge Isotopes Laboratories.
Prepurified gases were used as purchased from BOC. Phosphine
ligands were used as purchased from Strem Chemicals or donated from
Digital Specialty Co. Deuterations were performed with DOTf
generated by reacting triflic anhydride with D2O. trans-OsH(Br)-
Preparation of trans-Os(H)(SPh)(dppe)2 (1Os). Method 1.
A
slurry of NaSPh in THF (10 mL) was prepared by reacting NaOtBu
(38 mg, 0.40 mmol) with PhSH (44 mg, 0.40 mmol). The complex
trans-Os(H)Br(dppe)2 (0.218 g, 0.204 mmol) was added, and the
reaction mixture was refluxed for 3 h and then stirred for 50 h. The
31P NMR spectrum showed that the reaction was complete. The
suspension was chilled and filtered through THF-saturated Celite, and
the solvent was removed from the yellow filtrate under reduced pressure.
The resulting bright yellow powder was precipitated from THF (3 mL)
by addition of cold Et2O (10 mL) to give 0.28 g of crude product. This
was dissolved in benzene (20 mL), and the salts were removed by
filtering through benzene-saturated Celite. The volume of the filtrate
was reduced under vacuum to 2 mL, Et2O (4 mL) was added, and the
mixture was briefly cooled. The bright yellow solid (0.18 g, 80% yield)
was filtered out, washed with Et2O (5 mL), and dried under vacuum.
Method 2. A white suspension of LiSPh was prepared by reacting
HSPh (0.5 mL) in ether (10 mL) at 0 °C with nBuLi/hexanes (2.5 mL
of 1.6 M). The ether was evaporated, THF was added, followed by
Os(H)Br(dppe)2 (0.49 g, 0.45 mmol) as above, and the mixture was
refluxed for 48 h. IR: 2020 (m, νOsH). 1H NMR (C6D6): 7.5-6.75
(m, 40H, PC6H5), 6.63 (m, 2H, SC6H5), 6.26 (m, 3H, SC6H5), 2.80 (m,
4H CH2), 2.08 (m, 4H, CH2), -16.6 (quint, 1H, 2JHP ) 16.6 Hz, OsH).
31P NMR (C6D6): 28.0 ppm (s). FAB MS: calcd for C58H5432SP4192Os,
m/e 1098; obsd, 1098 (M+), 989 (M+ - SPh). Anal. Calcd for C58H54-
OsP4S: C, 63.49; H, 4.96. Found: C, 63.1; H, 4.9.
(dppe)2,10 RuCl2(DMSO)4,14 and cis-RuCl2(dppe)2 were prepared
15
according to literature methods. Other reagents were obtained com-
mercially and used as received.
Fast atom bombardment mass spectrometry (FAB MS) was carried
out with a VG 70-250S mass spectrometer using a 3-nitrobenzyl alcohol
(NBA) or magic bullet matrix with the sample dissolved in acetone.
NMR was performed on a Varian Unity-400 operating at 400 MHz for
1H, 61.47 MHz for 2D, 161.90 MHz for 31P, and 376.29 MHz for 19F,
1
a Varian Gemini 300 operating at 300 MHz for H, 75.462 MHz for
13C, 121.47 MHz for 31P, and 282.33 MHz for 19F, or a Varian Gemini
1
200 operating at 200 MHz for H. Variable-temperature T1 measure-
ments were made at 300 or 400 MHz using the inversion recovery
method with calibration of the 90°/180° pulse at each temperature. The
temperature of the probes was calibrated with the temperature
dependence of the chemical shifts of MeOH.16 Reported chemical shifts
refer to room-temperature conditions (19 °C) unless otherwise stated.
All 31P NMR spectra were proton decoupled unless specified otherwise.
31P NMR chemical shifts were referenced to external 85% H3PO4. 1H
NMR chemical shifts were measured relative to partially deuterated
solvent peaks but are reported relative to tetramethylsilane. 13C spectra
Preparation of trans-Os(H)(p-SC6H4F)(dppe)2 (1Os-F). The
preparation of this complex is analogous to the preparation of 1Os.
p-LiSC6H4F was prepared by addition of nBuLi (8.5 mL of 1.5 M
solution in hexanes, 13 mmol) to a solution of p-HSC6H4F (1.4 mL,
13 mmol) in 10 mL of Et2O. The resulting white powder was collected
by filtration, washed with Et2O, and dried under vacuum.
To Os(H)(Br)(dppe)2 (643 mg, 0.60 mmol) and p-LiSC6H4F (166
mg, 1.24 mmol) under Ar was added about 50 mL of THF. The
solution was refluxed for 17.5 h and then cooled, and the volume was
reduced to 15-20 mL. 31P NMR of the reaction mixture showed a
single peak. Addition of Et2O caused a bright yellow solid to precipitate
out of solution. The remaining green-yellow liquid was removed by
syringe, and the solid was dried under vacuum. It was then stirred
overnight in toluene and filtered through toluene-saturated Celite. The
volume of the solution was reduced, Et2O was added, and the mixture
was cooled; the Os(H)(p-SC6H4F)(dppe)2 was collected by filtration
and washed twice with Et2O. The yield was increased by reducing
1
are H-decoupled, and their chemical shifts are referenced relative to
solvent peaks and reported relative to TMS. 19F chemical shifts are
(9) Chin, B.; Lough, A. J.; Morris, R. H.; Schweitzer, C. T.; D’Agostino,
C. Inorg. Chem. 1994, 33, 6278-6288.
(10) Maltby, P. A.; Schlaf, M.; Steinbeck, M.; Lough, A. J.; Morris, R.
H.; Klooster, W. T.; Koetzle, T. F.; Srivastava, R. C. J. Am. Chem.
Soc. 1996, 118, 8, 5396-5407.
(11) Heinekey, D. M.; Luther, T. A. Inorg. Chem. 1996, 35, 4396-4399.
(12) Forde, C. E.; Landau, S. E.; Morris, R. H. J. Chem. Soc., Dalton Trans.
1997, 1663-1664.
(13) Li, Z.; Taube, H. J. Am. Chem. Soc. 1994, 116, 9506-9513.
(14) Evans, I. P.; Spencer, A.; Wilkinson, G. J. Chem. Soc., Dalton Trans.
1973, 204.
(15) Bautista, M. T.; Cappellani, E. P.; Drouin, S. D.; Morris, R. H.;
Schweitzer, C. T.; Sella, A.; Zubkowski, J. J. Am. Chem. Soc. 1991,
113, 3, 4876-4887.
(16) Van Geet, A. L. Anal. Chem. 1970, 42, 679-680.

Protonation Reactions of trans-M(H)(SPh)(dppe)2
Inorganic Chemistry, Vol. 37, No. 7, 1998 1557
the volume of the mother liquor, adding more Et2O, cooling, and
filtering again. Yield: 310 mg (0.28 mmol, 46%). 1H NMR (CD2-
(H)(HSC6H5)(C52H48P4)]+, 1019.27 [190Os(H)(O2)(C52H48P4)]+, 1003.27
[
HBF4‚Et2O, instead of HOTf, can be used for the protonation; the
complex can also be made directly by reaction of 1Os with excess
acid in dichloromethane or from 2Os. The trace of water needed for
the reaction may come from the slightly impure acid or from elsewhere.
Treatment of 1Os with a 1:1 mixture of HOTf/DOTf in CD2Cl2 under
Ar produces deuterated isotopomers of 4Os. 1H NMR (CD2Cl2): -13.3
(1:1:1 t, JHD ) 14 ( 1 Hz).
Identification of trans-[Os(H)(N2)(dppe)2]BF4 (6Os). 2Os (120
mg, 0.101 mmol) was dissolved in 15-20 mL of CH2Cl2, and the
solution was stirred for 30 min under N2. Et2O was then added to
precipitate out a pale lavender powder, which was shown by 1H NMR
to contain both [Os(H)(N2)(dppe)2]+ and 2Os in the ratio 4:1. The
remaining solid (85 mg) was redissolved in CH2Cl2 and stirred under
N2 for an additional 3.5 h. The volume of the solution was then reduced
and Et2O again added to precipitate out a pale lavender powder, which
was washed twice with Et2O. 1H NMR showed this powder to consist
of 7:3 [Os(H)(N2)(dppe)2]+/2Os, as well as [Os(H)(H2)(dppe)2]+ and
Os(H)(Cl)(dppe)2. Attempted recrystallization from CH2Cl2/ Et2O under
N2 produced a mixture of hydrides. 1H NMR (CD2Cl2, hydride
region): -14.2 ppm (2JHP ) 17 Hz, OsH). 31P NMR (CD2Cl2): 30.8
ppm (s). IR (Nujol mull): 2170 cm-1 (νNN).
190Os(H)(O)(C52H48P4)]+, 987.28 [190Os(H)(C52H48P4)]+.
2
Cl2): 7.3 (d, JHH ) 7 Hz, 8 H, ortho PPh), 7.0-7.1 (m, 24 H, ortho
and meta PPh), 6.9 (t, 2JHH ) 8, 8 H, para PPh), 6.1 (br, 2 H, ortho or
meta SC6H4F), 5.7 (br, 2 H, ortho or meta SC6H4F), 2.8 (br, 4 H, PCH2),
2.2 (br, 4 H, PCH2), -17.0 ppm (quint, 2JHP ) 16 Hz, 1 H, OsH). 31
P
NMR (CD2Cl2): 30.4 ppm (s). 19F NMR (CD2Cl2): -127.0 ppm (Ar
F). Anal. Calcd for C58H53FOsP4S: C, 62.41; H, 4.88. Found: C,
62.0; H, 4.9.
Preparation of trans-[Os(H)(HSPh)(dppe)2]BF4 (2Os). Excess
HBF4‚Et2O (25 µL, 0.14 mmol) was added with stirring to 1Os (98
mg, 0.089 mmol) suspended in 15 mL of Et2O. After 10 min, the
deep yellow suspension had turned white. The white solid was collected
by filtration and dried under vacuum. Yield: 60% to quantitative. 1H
2
NMR (CD2Cl2): 7.1-7.4 (m, 36H, PPh), 7.0 (t, JHH ) 8, 1 H, para
2
SPh), 6.7 (t, JHH ) 8, overlaps peak at 6.6, 2 H, meta SPh), 6.6 (br,
3
3
4 H, ortho PPh), 5.8 (d, JHH ) 8, 2H, ortho SPh), 4.4 (br quint, JHP
) 4, 1 H, SH), 2.6 (br m, 4 H, PCH2), 2.1 (br m, 4 H, PCH2), -15.8
ppm (quint, 2JHP ) 18 Hz, 1 H, OsH). 31P NMR (CD2Cl2): 29.8 ppm
(s).
The protonation can also be performed with HOTf instead of HBF4‚
Et2O. We were unsuccessful in obtaining acceptable elemental analysis
on these very reactive thiol complexes.
Preparation of trans-[Os(H)(p-HSC6H4F)(dppe)2]OTf (2Os-F).
To a suspension of Os(H)(p-SC6H4F)(dppe)2 (80 mg, 0.072 mmol) in
about 20 mL of Et2O was added HOTf (8 µL, 0.09 mmol). After 15
min of stirring, no color change was observed and so more HOTf (8
µL, 0.09 mmol) was added. Within 5 min, the color had changed from
deep yellow to lavender. The solid was allowed to settle, and the
solution was removed by syringe. The powder was washed once with
Et2O and then dried under vacuum. Yield: 36 mg (0.028 mmol, 40%).
1H NMR (CD2Cl2): 7.4-6.9 (m; 32 H, PPh), 6.6 (br, 8 H, ortho PPh),
6.3 (t, J ) 8, 2 H, meta SC6H4F), 5.9 (br m, 2 H, ortho SC6H4F), 4.5
(br m, 1 H, SH), 3.6 (s, 1 H, free HSC6H4F), 2.7 (br m, 4 H, PCH2),
Preparation of trans-[Os(H)(O2)(dppe)2]X (X ) PF6 or OTf)
(7Os). Method 1 (PF6 Salt). Os(H)Br(dppe)2 (65 mg, 0.061 mmol)
was suspended in ethanol under Ar. NaPF6 (excess) was added and
the reaction mixture was briefly opened to air. The pale yellow
suspension was then sealed and stirred for 5 days, over which time its
1
color changed to pale pink-brown. 31P and H NMR spectra of the
reaction mixture confirmed that conversion to 7Os was complete. The
suspension was filtered in air and the filtrate washed with methanol to
give a pale brown solid, which was air-dried overnight in a desiccator.
The complex was also observed as the decomposition product of various
reactions. The solid is air-stable for days. Yield: 62.4 mg (0.053
mmol, 87%); identification by NMR (see below).
2
2.2 (br m, 4 H, PCH2), -15.7 ppm (quint, JHP ) 17 Hz, 1 H, OsH).
31P NMR (CD2Cl2): 29.8 ppm (s). 19F NMR (CD2Cl2): -77.3 (s,
Method 2 (OTf Salt). This reaction was conducted under Ar with
traces of oxygen present. To 1Os (35 mg, 0.023 mmol) suspended in
5 mL of benzene was added THF (0.8 mL) and then CH3OTf (5 µL,
0.04 mmol). After 2 h of stirring, more CH3OTf (2 µL, 0.02 mmol)
was added and the mixture was again stirred for 2 h. The resulting
peach solution was evaporated to dryness. The residue was dissolved
in THF, and brown-red crystals were obtained by slow diffusion of
benzene. The structure determined by single-crystal X-ray diffraction
SO3CF3-), -111.4 ppm (s, Ar F).
Identification of trans-[Os(H2)(HSPh)(dppe)2](BF4)2 (3Os).
A
CD2Cl2 solution of 1Os (10-50 mg, 0.009-0.046 mmol) in an NMR
tube was cooled to -78 °C. HBF4‚Et2O (25 µL, 0.14 mmol) was added
by syringe, and the sample was sealed and shaken briefly, until the
yellow solution had turned colorless. The tube was then transferred
to the NMR probe, which had been precooled to -30 °C. 1H NMR
(CD2Cl2): 11.6 (br, 35 H, H+/H2O), 7.4-7.1 (m, 37 H, PPh as well as
1
was confirmed by H and 31P NMR spectra of the remaining product.
SPh), 6.6 (br, 10 H, ortho PPh and possibly meta SPh), 5.9 (d, 3JHH
)
1H NMR (CD2Cl2): 7.4 (m, Ph), 7.3 (m, Ph), 7.2 (m, Ph; all
overlapping, 32 H), 6.9 (br, 8 H, ortho Ph), 2.8 (m, 4 H, PCH2), 2.1
(m, 4 H, PCH2), -4.6 ppm (quint, 2JHP ) 21 Hz, 1 H, OsH). 31P NMR
(CD2Cl2): 25.6 ppm (s).
7 Hz, 2 H, ortho SPh), 5.4 (quint br, 1 H, SH), 3.0 (br m, 4 H, PCH2),
2.4 (br m, 4 H, PCH2), -9.7 ppm (br, 2 H, Os(η2-H2)). VT T1 of
η2-H2 (ms)/temp (K): 55/193, 36/233, 34/253, 34/273, 34/283, 33/293,
30/298. 31P NMR (CD2Cl2): 20.8 ppm (s).
X-ray Structure Determination of trans-Ru(H)(SPh)(dppe)2.
Crystals of trans-Ru(H)(SPh)(dppe)2 were prepared by the slow
diffusion of ethanol into a saturated solution of the complex in benzene
in a purified N2 atmosphere. A yellow crystal of dimensions 0.10 ×
0.125 × 0.32 mm was mounted on a glass fiber and coated with epoxy
to prevent exposure to the air. The mounted crystal was placed on an
Enraf-Nonius CAD-4 diffractometer at 298 K. Unit cell parameters
were determined by least-squares refinement of 15 reflections with 21.2
< 2θ < 22.5°. The unique space group P21/n was determined. The
data were corrected for Lorentz and polarization effects, and an
absorption correction was applied using ψ-scan data. Minimum and
maximum transmission coefficients were 0.4689 and 0.4893.
After the sample had been kept at -78 °C for several hours, another
1H NMR spectrum was taken at room temperature. 1H NMR (hydride
region): -9.7 (br, 1.6 H, 3Os) -11.5 (m, 1 H, [Os(H2)(Cl)(dppe)2]+),10
2
-13.2 (br, 10 H, 4Os), -15.7 (quint, JHP ) 18 Hz, 4.5 H, 2Os). In
our solutions, 3Os has never been the major species present at room
temperature.
Identification of trans-[Os(H2)(H2O)(dppe)2](OTf)2 (4Os). To 1Os
(47 mg, 0.043 mmol) suspended in 10 mL of benzene was added CH3-
OTf (7 µL, 0.062 mmol), with stirring. After 5 min the reaction mixture
was clear. After a total of 20 min, it had become cloudy and slightly
orange. HOTf (6 µL, 0.068 mmol) was added, and a precipitate formed.
The volume of the solution was reduced, and the pale pink solid was
collected by filtration and washed with Et2O. On other occasions, the
solution was removed by syringe rather than filtered. Yield: 58% to
quantitative. 1H NMR (CD2Cl2): 11.1 (br, H+/H2O), 7.5-7.6 (br, 8
H, ortho PPh), 7.4-7.1 (m, PPh and free HSPh), 6.5 (br, 8 H, ortho
PPh), 3.6 (s, 1 H, free HSPh), 3.2 (s, 2 H, Os(H2O)), 2.9 (m, 4 H,
PCH2), 2.4 (m, 4 H, PCH2), -13.3 ppm (br quint, 2JHP ) 10 Hz, 2 H,
Os(η2-H2)). T1 of η2-H2 (ms)/temp (K): 47/294, 41/277, 38/252, 40/
238, 50/221. 31P NMR (CD2Cl2): 34.9 ppm (s). 19F NMR (CD2Cl2):
277.1 (very small), -77.2 ppm (s, SO3CF3-). FAB-MS: obsd, m/e
1170, 1097, 1021, 1003, 987 (largest peak); calcd, m/e 1097.30 [190Os-
The structure was solved and refined using the SHELXTL/PC17
package. Refinement was by full-matrix least-squares method on F2
using all data (negative intensities included). The weighting scheme
2
2
was w ) 1/[σ2(Fo ) + (0.0439P)2], where P ) (Fo + 2Fc2)/3.
Hydrogen atoms were included in calculated positions and treated as
riding atoms. The position of the hydride atom was refined with an
isotropic thermal parameter.
(17) Sheldrick, G. M. SHELXTL/PC V5.0; Siemens Analytical X-ray
Instruments Inc.: Madison, WI.

1558 Inorganic Chemistry, Vol. 37, No. 7, 1998
Bartucz et al.
Table 1. Summary of Crystal Data, Details of Intensity Collection,
Table 4. Selected Bond Lengths (Å) for 7Os
and Least-Squares Refinement Parameters
Os(1)-P(4)
Os(1)-P(1)
Os(1)-P(2)
Os(1)-P(3)
P(1)-C(21)
P(1)-C(11)
P(1)-C(1)
P(3)-C(61)
P(3)-C(51)
P(3)-C(3)
C(1)-C(2)
2.351(2)
2.360(2)
2.368(1)
2.380(1)
1.818(6)
1.822(5)
1.858(5)
1.821(6)
1.834(5)
1.837(6)
1.528(7)
Os(1)-H(1Os)
Os(1)-O(1)
Os(1)-O(2)
O(1)-O(2)
P(2)-C(31)
P(2)-C(41)
P(2)-C(2)
1.29(4)
2.061(4)
2.064(3)
1.430(5)
1.812(6)
1.813(6)
1.828(6)
1.789(6)
1.826(6)
1.839(5)
1.523(8)
1Ru
7Os‚3C6H6
empirical formula
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
C58H54P4RuS
11.226(2)
33.260(7)
13.586(3)
90
104.01(3)
90
C71H67F3O5OsP4S
13.259(2)
13.269(2)
18.201(3)
86.13(1)
84.06(1)
85.48(1)
3169.5(9)
2
P(4)-C(71)
P(4)-C(81)
P(4)-C(4)
4922(2)
4
C(3)-C(4)
fw
1008.02
monoclinic
P21/n
293(2)
0.710 73
1.360
0.529
0.4689-0.4839
0.0463
1403.39
triclinic
P1h
Table 5. Selected Bond Angles (deg) for 7Os
H(1Os)-Os(1)-O(1) 156(2)
cryst system
space group
T, K
H(1Os)-Os(1)-O(2) 164(2)
H(1Os)-Os(1)-P(4)
O(1)-Os(1)-P(4)
O(2)-Os(1)-P(4)
H(1Os)-Os(1)-P(2)
O(1)-Os(1)-P(2)
O(2)-Os(1)-P(2)
P(4)-Os(1)-P(1)
P(4)-Os(1)-P(2)
P(1)-Os(1)-P(2)
O(2)-O(1)-Os(1)
O(1)-Os(1)-O(2)
C(21)-P(1)-C(11)
C(21)-P(1)-C(1)
C(11)-P(1)-C(1)
C(21)-P(1)-Os(1)
C(11)-P(1)-Os(1)
C(1)-P(1)-Os(1)
C(61)-P(3)-C(51)
C(61)-P(3)-C(3)
C(51)-P(3)-C(3)
C(61)-P(3)-Os(1)
C(51)-P(3)-Os(1)
C(3)-P(3)-Os(1)
62(2)
H(1Os)-Os(1)-P(1)
78(2)
173(2)
94.4(1) O(1)-Os(1)-P(1)
125.9(1)
85.4(1)
94(2)
83.2(1)
88.6(1)
84.02(5)
99.77(5)
171.05(5)
69.6(2)
λ, Å
0.710 73
1.471
2.205
calc, g cm-3
135.0(1) O(2)-Os(1)-P(1)
F
µ, mm-1
95(2)
H(1Os)-Os(1)-P(3)
88.7(1) O(1)-Os(1)-P(3)
82.7(1) O(2)-Os(1)-P(3)
139.65(5) P(4)-Os(1)-P(3)
100.41(5) P(1)-Os(1)-P(3)
81.95(5) P(2)-Os(1)-P(3)
69.8(2) O(1)-O(2)-Os(1)
40.6(2)
transm coeff
R(Fo) (I > 2σ(I))a
R2w(Fo) (all data)b
0.0490
0.1039
0.1291
a R ) ∑||Fo| - |Fc||/∑|Fo|. R2w ) [∑{w(Fo2 - Fc2)2}/∑{w(Fo2)2}]1/2
.
b
Table 2. Selected Bond Lengths (Å) for 1Ru
104.0(3) C(31)-P(2)-C(41)
101.6(3) C(31)-P(2)-C(2)
104.9(3) C(41)-P(2)-C(2)
122.3(2) C(31)-P(2)-Os(1)
113.9(2) C(41)-P(2)-Os(1)
108.3(2) C(2)-P(2)-Os(1)
104.2(3) C(71)-P(4)-C(81)
103.9(3) C(71)-P(4)-C(4)
102.6(3) C(81)-P(4)-C(4)
118.9(2) C(71)-P(4)-Os(1)
119.1(2) C(81)-P(4)-Os(1)
106.0(2) C(4)-P(4)-Os(1)
104.4(3)
105.1(3)
101.6(3)
115.4(2)
124.1(2)
103.8(2)
102.5(3)
102.3(3)
103.3(3)
119.2(2)
119.6(2)
107.6(2)
Ru(1)-S(1)
Ru(1)-P(2)
Ru(1)-P(4)
S(1)-C(5)
P(1)-C(11)
P(2)-C(2)
P(2)-C(41)
P(3)-C(51)
P(4)-C(4)
P(4)-C(81)
C(3)-C(4)
2.526(1)
2.325(1)
2.351(1)
1.754(5)
1.846(5)
1.852(5)
1.833(5)
1.829(5)
1.857(4)
1.829(4)
1.516(6)
Ru(1)-P(1)
Ru(1)-P(3)
Ru(1)-H(1Ru)
P(1)-C(1)
P(1)-C(21)
P(2)-C(31)
P(3)-C(3)
P(3)-C(61)
P(4)-C(71)
C(1)-C(2)
2.332(1)
2.340(1)
1.52(4)
1.866(4)
1.834(5)
1.844(5)
1.848(4)
1.839(5)
1.844(5)
1.472(6)
The structure was solved as above. The weighting scheme was w
) 1/[σ2(Fo2) + (0.0424P)2], where P ) (Fo2 + 2Fc2)/3. Hydrogen atoms
were included in calculated positions and treated as riding atoms. The
position of the hydride atom was refined with an isotropic thermal
parameter. One of the C6H6 molecules is disordered over two sites
Table 3. Selected Bond Angles (deg) for 1Ru
P(1)-Ru(1)-S(1)
P(4)-Ru(1)-S(1)
P(1)-Ru(1)-P(3)
P(2)-Ru(1)-P(1)
P(2)-Ru(1)-P(4)
100.11(4) P(2)-Ru(1)-S(1)
87.95(5) P(3)-Ru(1)-S(1)
176.31(5) P(2)-Ru(1)-P(3)
85.18(4) P(1)-Ru(1)-P(4)
168.25(5) P(3)-Ru(1)-P(4)
103.44(5)
83.24(4)
95.60(4)
95.81(4)
82.70(4)
-
with site occupancies 0.5:0.5, and the CF3SO3 anion is disordered
over two sites with occupation parameters 0.62:0.38.
Crystal data are provided in Table 1, and selected bond lengths and
angles are given in Tables 4 and 5.
H(1Ru)-Ru(1)-S(1) 173.7(14) H(1Ru)-Ru(1)-P(1) 85.8(14)
H(1Ru)-Ru(1)-P(2) 78.9(14) H(1Ru)-Ru(1)-P(3) 90.8(14)
H(1Ru)-Ru(1)-P(4) 89.5(14) C(5)-S(1)-Ru(1)
117.8(2)
125.4(2)
118.4(2)
108.1(2)
122.9(2)
121.4(2)
106.5(2)
120.9(2)
123.6(2)
105.6(2)
119.5(2)
122.8(2)
108.81(14)
107.7(3)
111.3(3)
C(21)-P(1)-C(11)
C(21)-P(1)-C(1)
C(11)-P(1)-C(1)
C(41)-P(2)-C(31)
C(41)-P(2)-C(2)
C(31)-P(2)-C(2)
C(51)-P(3)-C(61)
C(51)-P(3)-C(3)
C(61)-P(3)-C(3)
C(81)-P(4)-C(71)
C(81)-P(4)-C(4)
C(71)-P(4)-C(4)
C(2)-C(1)-P(1)
C(1)-C(2)-P(2)
99.7(2) C(21)-P(1)-Ru(1)
99.7(2) C(11)-P(1)-Ru(1)
101.7(2) C(1)-P(1)-Ru(1)
100.3(2) C(41)-P(2)-Ru(1)
104.8(2) C(31)-P(2)-Ru(1)
97.2(2) C(2)-P(2)-Ru(1)
100.2(2) C(51)-P(3)-Ru(1)
101.2(2) C(61)-P(3)-Ru(1)
101.9(2) C(3)-P(3)-Ru(1)
100.8(2) C(81)-P(4)-Ru(1)
103.3(2) C(71)-P(4)-Ru(1)
98.1(2) C(4)-P(4)-Ru(1)
113.1(3) C(4)-C(3)-P(3)
112.3(3) C(3)-C(4)-P(4)
Results and Discussion
Preparation of the Complexes trans-M(H)(SR)(dppe)2.
The new, deep yellow hydride complex trans-Ru(H)(SPh)-
(dppe)2 (1Ru) is synthesized in four high-yield steps: (1) from
RuCl3‚3H2O to cis-RuCl2(DMSO)4; (2) to cis- and trans-RuCl2-
(dppe)2; (3) to trans-[Ru(H2)(H)(dppe)2]BPh4 (5Ru);15 (4) to
complex 1Ru. The dihydrogen ligand of 5Ru is very labile
and is easily displaced by the thiophenolate anion (eq 2), which
trans-[Ru(H2)(H)(dppe)2]BPh4 + NaSPh f
trans-Ru(H)(SPh)(dppe)2 + H2 + NaBPh4 (2)
Crystal data are provided in Table 1, and selected bond lengths and
angles are given in Tables 2 and 3.
is conveniently generated by the reduction of PhSSPh with
NaBH4 in EtOH. A related complex, trans-Ru(H)(SPh)(dmpe)2,
is detected in solution by 1H NMR when cis-Ru(H)2(dmpe)2 is
reacted with PhSH.19 This reaction is also thought to proceed
via a dihydrogen complex, in this case trans-[Ru(H2)(H)(dmpe)2]-
SPh. However this reaction proceeds further to produce cis-
and trans-Ru(SPh)2(dmpe)2.
X-ray Structure Determination of trans-[Os(H)(O2)(dppe)2]-
OTf‚3C6H6. Data were collected on a Siemens P4 diffractometer using
graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å). The
intensities of three standard reflections measured every 97 reflections
showed less than 4% variation. The data were corrected for Lorentz
and polarization and absorption effects.18
(18) Sheldrick, G. M. SHELXA-90, Program for Absorption Correction;
(19) Field, L. D.; Hambley, T. W.; Yau, B. C. K. Inorg. Chem. 1994, 33,
2009-17.
University of Go¨ttingen: Go¨ttingen, Germany,

Protonation Reactions of trans-M(H)(SPh)(dppe)2
Inorganic Chemistry, Vol. 37, No. 7, 1998 1559
The new, yellow complex trans-Os(H)(SPh)(dppe)2 (1Os) is
synthesized in three high-yield steps: (1) from OsO4 to (NH4)2-
[OsBr6]; (2) to trans-Os(H)(Br)(dppe)2;10 (3) to complex 1Os.
The last step involves the displacement of bromide by thiophe-
nolate in THF at reflux (eq 3). The synthesis of trans-Os(H)-
(p-SC6H4F)(dppe)2 (1Os-F) is directly analogous to that of 1Os.
trans-Os(H)(Br)(dppe)2 + NaSPh f
trans-Os(H)(SPh)(dppe)2 + NaBr (3)
An alternative synthetic route similar to that of eq 2 failed to
yield pure 1Os. Reaction of [Os(H2)H(dppe)2]BF4 (5Os) with
LiSPh in THF leads primarily (90%) to deprotonation and
formation of the dihydride complex Os(H)2(dppe)220 with only
10% formation of 1Os. This result is somewhat unexpected,
since PhS- should not be a strong enough base to deprotonate
5Os. The pKa values of the PhSH and the dihydrogen complex
are pKa ) 6.4 (measured on the aqueous scale)8 and 13.6
(measured in THF and extrapolated to the aqueous scale),21
respectively. This could be a thermodynamic effect where the
basicity of the thiophenolate is enhanced in the THF solvent. It
could also be a kinetic effect since it is known that deprotonation
of 5Os by a strong base is much faster (t1/2 , 1 min) than loss
of H2 (t1/2 . 1 h) at 20 °C.21
Figure 1. Crystallographic labeling scheme for 1Ru. Thermal dis-
placement parameters are at the 30% probability level.
ligand with a chloride ligand,24 but in the case of 1Os, the
nucleophilicity of the thiolate ligand and steric hindrance to
reaction at the hydride seem to determine the reaction outcome.
X-ray Crystal Structure Determination of Ru(H)(SPh)-
(dppe)2. The crystal structure determination of 1Ru verifies
the trans, octahedral geometry (Figure 1). The geometry is
distorted by steric interactions as described below. The hydride
position refined to a reasonable Ru-H distance of 1.52(4) Å.
The SPh ligand is coordinated to the metal in a bent
configuration with a Ru-S-C(5) angle of 117.8(2)°. The
phenyl ring is sandwiched between two phenyl rings of one of
the dppe ligands. The Ru-S bond length of 2.526(1) Å is
considerably longer than the average value of 2.238 Å observed
for six ruthenium arenethiolates24 and the 2.472(1) Å distance
in the closely related complex trans-Ru(SPh)2(dmpe)2.19 This
is caused by a combination of two effects: the strong trans
influence of the hydride ligand25 and the steric crowding caused
by the dppe ligands. The sulfur is pushed by interactions with
the rings on P(1) and P(2) toward P(3) and P(4) so that the
S-Ru-P angles are 100.11(4) and 103.44(5)° for the first two
phosphorus atoms and 83.24(4) and 87.95(5)° for the last two.
A similar distortion of octahedral geometry was reported for
the complexes 8Ru9 and 8Os10 where the M-Cl bond tilts
toward one dppe ligand because of Cl-ring interactions.
The ruthenium-phosphorus bonds are slightly longer to the
dppe ligand toward which the M-S bond is tilted (Ru-P(3) )
2.340(1), Ru-P(4) ) 2.351(1) Å) than to the other dppe ligand
(Ru-P(1) ) 2.332(1), Ru-P(2) ) 2.325(1) Å). These Ru-P
distances are very close to the ones observed in trans-Ru(SPh)2-
Properties of the Complexes trans-M(H)(SR)(dppe)2. A
C6D6 solution of each of the complexes causes a singlet to
appear in the 31P{1H} spectra as expected for the trans
1
stereochemistry. Accordingly, the H spectra have quintets in
the high-field region again indicating that the hydride couples
1
to four equivalent phosphorus nuclei. The H resonances of
the thiolate ligands are found in the region between 6.3 and 7.0
ppm, somewhat upfield of the dppe ring protons. The presence
of two different axial groups (hydride and thiolate) causes the
methylene protons of the dppe to resonate in two distinct regions
near 3 and 2 ppm.
The hydride stretch of 1Os in Nujol at 2020 cm-1 is higher
than that of 1Ru at 1918 cm-1. This indicates that the Os-H
bond is stronger than the Ru-H bond. The FAB-MS of 1Os
reveals a parent ion and a fragment caused by loss of SPh-.
The cyclic voltammograms of 1Ru in CH2Cl2/n-Bu4NPF6 and
1Os in THF/n-Bu4NPF6 show a reversible wave with a M(III)/
M(II) reduction potential versus FeCp2+/FeCp2 of 0.07 and
-0.65 V, respectively. These translate into approximately 0.7
and 0.0 V vs NHE. The values are predicted to be 0.5 and 0.2
V, respectively, on the basis of Lever’s empirical method which
involves adding ligand parameters EL.22 Of the ligands X that
we have examined in the series trans-M(H)(X)(dppe)2 (X )
H, Cl, SPh; M ) Fe, Ru, Os), the SPh ligand has the most
negative EL value (-0.53 V vs -0.4 V for hydride23 and -0.24
V for chloride) and therefore makes the metal in the complex
the most reducing and potentially the most basic with respect
to protonation (see below). A second reversible Os(IV)/Os-
(III) wave is observed for 1Os at 0.25 V.
19
26
(dmpe)2 and trans-[Ru(H2)H(dppe)2]BPh4 and shorter than
those in trans-[Ru(H2)Cl(dppe)2]PF6 (2.385(5) Å on average).9
Observation of the Complexes trans-[M(H)(SHPh)-
(dppe)2]+ (2Ru, 2Os). When a suspension of the complexes
1Ru or 1Os in Et2O is treated with HBF4‚Et2O under Ar, then
an unstable precipitate forms which is red (2Ru) or white (2Os),
respectively.
Complex 1Os slowly reacts with CH2Cl2 or CD2Cl2 solvent
to give trans-Os(H)(Cl)(dppe)2 and PhSCH2SPh. The latter
product was identified by the CH2 1H NMR resonance at 4.3
ppm. Usually chlorinated solvents react to replace the hydride
trans-M(H)(SPh)(dppe)2
1Ru, 1Os
+ HBF4‚Et2O f
trans-[M(H)(SHPh)(dppe)2]BF4
2Ru, 2Os
+ Et2O (4)
(20) Earl, K. A.; Jia, G.; Maltby, P. A.; Morris, R. H. J. Am. Chem. Soc.
1991, 113, 3027-3039.
(21) Cappellani, E. P.; Drouin, S. D.; Jia, G.; Maltby, P. A.; Morris, R.
H.; Schweitzer, C. T. J. Am. Chem. Soc. 1994, 116, 3375-3388.
(22) Lever, A. B. P. Inorg. Chem. 1990, 29, 1271-1285.
(23) Morris, R. H. Inorg. Chem. 1992, 31, 1471-1478.
The osmium complex is the more stable and has been character-
(24) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.

1560 Inorganic Chemistry, Vol. 37, No. 7, 1998
Bartucz et al.
Scheme 2
Scheme 3
1
ized in solution by H and 31P NMR. Prepared in this way,
2Os reacts with both dichloromethane and THF, the two solvents
in which it dissolves. When it is dissolved in CD2Cl2 under
Ar, NMR spectra of the solution show that 2Os predominates
while [Os(H2)(Cl)(dppe)2]+ (8Os)10 is present in small and
variable amounts.
Red 2Ru produces a yellow solution when dissolved in
acetone-d6 under Ar. The 1H and 31P NMR spectra both indicate
the presence of a mixture of products. The major species, trans-
[Ru(H)(SHPh)(dppe)2]+, shows in the 31P{1H} NMR spectrum
a singlet at 64.1 ppm and in the 1H NMR spectrum a quintet at
-22.5 ppm (2JPH ) 19.3 Hz) due to the hydride and a broad
singlet at 3.8 ppm assigned to the SH resonance.
Reactions of Complexes 2 with Small Gas Molecules.
Complexes 2 react rapidly with 1 atm of dihydrogen to give
the dihydrogen complexes trans-[M(H2)H(dppe)2]+ (5Ru, 5Os)
and free thiol (eq 5).
The trans stereochemistry of 2Os is indicated by three spectral
features. First, the complex has one singlet resonance in the
31P{1H} NMR spectrum at 29.8 ppm. Second, it has a binomial
quintet at -15.8 ppm in the 1H NMR spectrum for the hydride
resonance. And third, it has a broad thiol resonance at 4.4 ppm
3
which is also a binomial quintet with JPH ) 4 Hz. The T1 of
the hydride resonance is 420 ( 25 ms at 298 K, which rules
out the possibility that 2Os is a dihydrogen complex. The
hydride peak integrates as expected in a 1:1 ratio to the broad
quintet of the SH at 4.4 ppm.
trans-[M(H)(SHPh)(dppe)2]+ + H2 f
trans-[M(H)(H2)(dppe)2]+ + HSPh (5)
The thiol ligand in this complex is very labile, and its
1
exchange with free HSPh can be observed in a H NMR spin
saturation transfer experiment. Irradiation of the SH proton at
4.4 ppm causes an inversion of a singlet resonance at 3.4 ppm,
which is due to the SH proton in free thiophenol.
Complex 2Os in CD2Cl2 reacts within seconds with H2 to
give the dihydrogen complex 5Os (Scheme 3). Complex 2Ru
as a suspension in diethyl ether reacts to give 5Ru as the major
product. These are the first reports of a reaction where
dihydrogen displaces a thiol ligand to produce a dihydrogen
complex.27
When the protonation of 1Os in CD2Cl2 is carried out at 193
K, complex 2Os is the exclusive product (27.9 ppm in the 31P
NMR spectrum) apart from a small amount of [Os(H2)(Cl)-
(dppe)2]+ (20.7 ppm). The latter is probably produced by
reaction of 1Os with CD2Cl2. Therefore it appears that
protonation at sulfur is both kinetically and thermodynamically
preferred over protonation at the Os-H bond (Scheme 2).
We anticipated that replacing the phenyl substituent of the
thiolate with an electron-withdrawing p-fluorophenyl group
might disfavor protonation at sulfur and favor protonation at
the Os-H to produce the tautomeric trans-[Os(H2)(SAr)-
(dppe)2]+ complex. However, like 1Os, trans-Os(H)(p-SC6H4F)-
(dppe)2 is singly protonated by HOTf in Et2O to form the
hydride thiol tautomer. trans-[Os(H)(SHC6H4-4-F)(dppe)2]OTf
(2Os-F) was identified by the similarity of its NMR spectra to
those of 2Os. For 2Os-F, the 31P NMR spectrum has a singlet
Even dinitrogen displaces the thiol ligand of 2Os in CD2Cl2
(Scheme 3). When 2Os is dissolved in dichloromethane under
1
an N2 atmosphere, the major species observed by H and 31P
NMR is trans-[Os(H)(N2)(dppe)2]+ (6Os). Unfortunately, at-
tempted crystallization only resulted in a pale lavender mixture
of complexes. The dinitrogen stretching frequency is 2170
cm-1, an unusually high frequency for a complex with a stable
dihydrogen analogue. Most stable dihydrogen complexes of a
d6 metal ion have corresponding dinitrogen complexes with νNN
in the range 2060-2150 cm-1 23
The dinitrogen complex was
.
also observed in a reaction of 1Os in CD2Cl2 under Ar with
N2-saturated CH3OTf where, presumably, CH3SPh is also
produced.
1
at 29.8 ppm, while the H NMR spectrum has a well-resolved
quintet at -15.7 ppm for the hydride and broad quintet at 4.5
ppm for the thiol SH. All the 1H chemical shifts are within 0.1
ppm of those for 2Os. Apparently adding a para fluorine to
the thiolate ring does not substantially reduce the basicity of
the sulfur relative to that of the hydride.
The dinitrogen ligand in 6Os is extremely labile and is
replaced by dihydrogen after only a few seconds of bubbling
H2 through the solution. In contrast, N2 does not displace H2
from the complex when a solution of [Os(H)(H2)(dppe)2]+ is
shaken in a N2-filled NMR tube.
O2 reacts with 2Os, 5Os, or 6Os to give the red-brown η2-
dioxygen complex trans-[Os(H)(O2)(dppe)2]+ (7Os) (Scheme
3). This complex was also prepared by the reaction of trans-
(25) Frenz, B. A.; Ibers, J. A. In Transition Metal Hydrides; Muetterties,
E. L., Ed.; Marcel Dekker Inc.: New York, 1971.
(26) Albinati, A.; Klooster, W.; Koetzle, T. F.; Fortin, J. B.; Ricci, J. S.;
Eckert, J.; Fong, T. P.; Lough, A. J.; Morris, R. H.; Golombek, A.
Inorg. Chim. Acta 1997, 259, 351-357.
(27) Jessop, P. G.; Morris, R. H. Coord. Chem. ReV. 1992, 121, 155-284.

Protonation Reactions of trans-M(H)(SPh)(dppe)2
Inorganic Chemistry, Vol. 37, No. 7, 1998 1561
Figure 3. 1H NMR spectrum in the high-field region at 253 K of 1Os
after reaction in CD2Cl2 at 193 K with a large excess of HBF4‚Et2O.
sented by the quintet at -15.7 ppm, and 30% trans-[Os(H2)-
(SHPh)(dppe)2]2+ (3Os), the broad singlet at -9.5 ppm. 31P
NMR peaks at 27.9 and 18.8 ppm, respectively, correspond to
these two resonances.
Figure 2. Crystallographic labeling scheme for the cation of 7Os.
Thermal displacement parameters are at the 50% probability level.
1Os + excess HBF4‚Et2O CD Cl , 193 K8
2Os +
2
2
Os(H)(Br)(dppe)2 with NaPF6 in EtOH under a mixture of argon
and air. The [Os(H)(dppe)2]+ binding site has a high affinity
for dioxygen. This binding site also has a high affinity for CH3-
CN,28 but a 4.5-fold excess of CH3CN does not displace O2
from this complex in CD2Cl2 after 2 days at 20 °C.
Figure 2 shows the structure of the cation of 7Os, and Tables
4 and 5 list selected bond lengths and angles. The Os-H(1Os)
distance is artificially short at 1.29(4) Å. The O-O distance
is 1.430(5) Å. The η2-O2 ligand is oriented along the P(1)-
Os-P(4) axis, and the Os-P(1) and Os-P(4) bonds are bent
away from the O-O bond, with a P(1)-Os-P(4) angle of
139.65(5)°. The P(2)-Os-P(3) angle is 171.05(5)°, oriented
toward the η2-dioxygen ligand. The structure of 5Os is very
similar to that of [Os(H)(O2)(dcpe)2]+, which has an O-O bond
distance of 1.45(1) Å along the P(2)-Os-P(4) axis, a P(2)-
Os-P(4) angle of 136.3(1)° away from the O2, and a P(1)-
Os-P(3) angle of 169.2(1)° toward the O2.29
The dihydrogen ligand of 5Os has been located crystallo-
graphically in an orientation similar to that of this O2 ligand,
parallel to a P-Os-P axis.30 However, the P-Os-P angle
along this axis is 176.3° and so it does not bend as sharply
away from the Os-(H-H) bonds as from the Os-(O-O)
bonds. In these complexes, both electronic and steric forces
contribute to the bending of one P-Os-P angle away from
the π-bonding ligand. Electronically, the partial oxidative
addition of the ligand imposes a distortion toward a 7-coordinate
structure. Sterically, the alignment of the π-bonding ligand
along the P-Os-P axis creates crowding that can only be
relieved by a smaller P-Os-P angle or by longer metal-ligand
distances. The P-Os-P angle is larger in [Os(H)(H2)(dppe)]+,
consistent with the presence of a very small π-bonding ligand
which has not been significantly reduced.
2+ + 8Os (6)
trans-[Os(H2)(SHPh)(dppe)2]
3Os
The 1H NMR signal at -9.5 is assigned to a coordinated
dihydrogen because of its short minimum T1 time of 34 ms at
272 K and 400 MHz. As the temperature is raised from 193 to
280 K, the T1 of the dihydrogen resonance at -9.5 ppm goes
to a minimum value of 34 ms (see Experimental Section) but
then abruptly appears to get shorter as it starts to react to form
another complex 4Os (see below) above 280 K. An H-H
distance of between 0.98 and 1.24 Å can be calculated from
this T1 value after correcting for other sources of dipolar
relaxation and assuming fast or slow motion of the HH ligand,
respectively.20 Several attempts to measure the H,D coupling
in this complex failed.
It is only possible to resolve the thiol proton resonance of
3Os at low temperature (253 K); at other temperatures, it
overlaps with other peaks. The assignment of the peaks due to
3Os was confirmed by a heteronuclear H{31P} NMR experi-
1
ment at 250 K in which the 31P peak at 20.8 ppm (arising from
1
3Os) was decoupled from the protons as a H NMR spectrum
was collected. This produced a 1H NMR spectrum that showed
sharpening of the peaks at 2.4 (CH2), 3.0 (CH2), 5.4 (SH), 5.9
(ortho SPh), and 6.6 ppm (ortho PPh). The ratios of the integrals
of the peaks at 5.4 and 5.9 ppm relative to the integral of the
hydride peak are 1:1 and 2:1, as expected.
In VT experiments starting at low temperature, a dihydrogen
resonance at -13.2 ppm attributed to trans-[Os(H2)(OH2)-
(dppe)2]2+ (4Os) starts to appear at temperatures above 273 K
and grows in intensity with increasing temperature, while the
intensity of the resonance at -9.5 ppm decreases at the same
time. The appearance of the peak at -13.2 ppm is accompanied
by a set of new resonances for the ethylene backbone of 4Os at
2.42 and 2.90 and of resonances at ∼3.6 ppm and ∼3.2 ppm
(shifts are temperature-dependent by (0.1 ppm) assigned to free
PhSH and coordinated H2O, respectively. The 3.2 ppm peak
disappears 30 min after D2O is added to the solution. In the
31P NMR spectrum a new singlet at 33.1 ppm for 4Os is
observed. Complex 4Os was prepared independently and the
dihydrogen (or HD) ligand was characterized by a minimum
1H T1 value of 38 ms at 250 K and 300 MHz and an H-D
coupling constant of 14 ( 1 (see Experimental Section).
Therefore the thiol ligand in 3Os is displaced by water,
Observation of Dicationic Dihydrogen Complexes. When
a large excess of HBF4‚Et2O is added to 1Os in CD2Cl2 at 193
K under Ar, two major peaks are observed in the high-field
region of the 1H NMR spectrum along with a small amount of
the chloride complex 8Os (Figure 3). Even under strongly
acidic conditions the mixture consists of 70% 2Os, as repre-
(28) Schlaf, M.; Lough, A. J.; Maltby, P. A.; Morris, R. H. Organometallics
1996, 15, 2270-2278.
(29) Mezzetti, A.; Zangrando, E.; Del Zotto, A.; Rigo, P. J. Chem. Soc.,
Chem. Commun. 1994, 1597-1598.
(30) Albinati, A.; Klooster, W.; Koetzle, T. F.; Ricci, J. S.; Maltby, P. A.;
Lough, A. J.; Morris, R. H. Manuscript in preparation.

1562 Inorganic Chemistry, Vol. 37, No. 7, 1998
Bartucz et al.
originating probably from the acid (eq 7). A similar reaction
for less than 30 min. The labile thiol complexes 2Os and 3Os
react quickly, and 4Os reacts more slowly. Presumably the
ultimate conversion of 4Os to 5Os involves the loss of the less
labile aqua ligand and is therefore somewhat slower than the
direct reaction of 2Os or 3Os with H2(g). In all cases free PhSH
2+ + H3O+ a
trans-[Os(H2)(SHPh)(dppe)2]
3Os
2+ + HSPh + H+ (7)
trans-[Os(H2)(OH2)(dppe)2]
1
was identified in the H NMR spectrum as a reaction product
4Os
by the appearance of a broad thiol proton resonance at ∼3.6
ppm (s), while the water released probably contributes to the
acid peak, observed at 13 ppm.
was described by Halcrow, Chaudret, and Trofimenko, who
found that reaction of Ru(tris(pyrazol-1-yl)borate)(PCy3)(H2)-
(H) with HBF4‚Et2O or with HOTf gives [Ru(tris(pyrazol-1-
yl)borate)(PCy3)(H2O)(H2)]+.31 We have evidence that eq 7 can
be partially reversed by cooling the sample below 273 K.32
Addition of HOTf or HBF4 to 1Os or 2Os at 293 K produces
a mixture of 2Os, 3Os, 4Os, and free HSPh. Addition of excess
PPh3 (as a base) to this sample causes the conversion first of
the 3Os into 2Os and then, when more PPh3 is added, of the
4Os into 2Os. Since both 3Os and 4Os are deprotonated by
Conclusions
Although the thiolate ligand is strongly electron-donating to
the metal, as indicated by the electrochemical results, protonation
does not take place at the metal or metal-hydride of the new
complexes trans-M(H)(SPh)(dppe)2 (M ) Ru, Os). Instead
protonation at the sulfur is kinetically and thermodynamically
preferred to give the very reactive complexes trans-[M(H)-
(SHPh)(dppe)2]+. The thiol ligand is very labile and can be
displaced by H2 to give the dihydrogen complexes trans-[M(H)-
(H2)(dppe)2]+. Dioxygen and dinitrogen also displace the thiol
in the osmium complex, thus producing a unique series of
complexes containing molecular H2, N2 and O2. Double
protonation of 1Os produces the first dihydrogen complex to
contain a coordinated thiol, trans-[Os(H2)(SHPh)(dppe)2]2+. The
fact that a thiolate ligand can be displaced from a platinum-
group metal by protonation and then reaction with dihydrogen
suggests that the reactivation of “sulfur-poisoned” catalysts
might be possible by such a reaction pathway.
PPh3 but 3Os is deprotonated first, its pKa is probably well under
+
2.7, the pKa of HPPh3
.
Reaction of the Dicationic Complexes with Dihydrogen.
A remarkable feature of the complexes 2Os, 3Os, and 4Os is
their reactivity with H2(g) (eq 8). Introduction of H2(g) into
2Os + 3Os + 4Os + H+ + excess H2 f
5Os + HSPh + 4Os + H+ + excess H2 f
5Os + HSPh + H3O+ (8)
Acknowledgment. We thank the NSERC Canada for an
operating grant, Johnson-Matthey for a loan of ruthenium and
osmium salts, and Digital Chemical Co. for a gift of dppe.
reaction mixtures containing the three complexes and acid in
CD2Cl2 or CH2Cl2 solution leads to the rapid and quantitative
formation of the complex [Os(H2)H(dppe)2]+ (5Os) as the only
product (aside from a little 8Os formed in the side reaction of
2Os with the solvent as discussed above). Of the three
complexes 2Os, 3Os, and 4Os, only 4Os remains detectable in
the spectrum after the introduction of H2(g) into the mixture
Supporting Information Available: Tables of crystal and structure
refinement data, atomic coordinates, thermal parameters, and bond
distances and angles for 1Ru (9 pages). An X-ray crystallographic
file, in CIF format, for the structure determination of 7Os is available
on the Internet only. Ordering and access information is given on any
current masthead page.
(31) Halcrow, M. A.; Chaudret, B.; Trofimenko, S. J. Chem. Soc., Chem.
Commun. 1993, 465-467.
(32) Schlaf, M. Ph.D. Thesis, University of Toronto, 1996.
IC971050G