Activation of metal hydride complexes by tri-tert-butylphosphine-platinum and -palladium groups

Article abstract of DOI:10.1021/ja070617h

The compounds HM(CO)₄SnPh₃, M = Os (10), Ru (11) are activated in the presence of Pt-(PBu^t₃)₂ and Pd(PBu^t₃)₂ toward the insertion of PhC ₂H into the M-H bond. The compounds PtOs(CO)₄-(SnPh ₃)(PBu^t₃)[μ-HCC(H)Ph], 12, and PtOs(CO) ₄(SnPh₃)(PBu^t₃)[μ-H ₂CCPh], 13, were obtained from the reaction of 10 with PhC ₂H in the presence of Pt(PBu^t₃)₂. Compounds 12 and 13 are isomers containing alkenyl ligands formed by the insertion of the PhC₂H molecule into the Os-H bond at both the substituted and unsubstituted carbon atoms of the alkyne. Both compounds contain a Pt(PBu^t₃) group that is bonded to the osmium atom and a bridging alkenyl ligand that is π-bonded to the osmium atom. The reaction of 11 with PhC₂H in the presence of Pt(PBu^t ₃)₂ yielded the products PtRu(CO)₄(SnPh ₃)(PBu^t₃)[μ-HC₂(H)Ph], 14, and PtRu(CO)₄(SnPh₃)(PBu^t₃)[μ-H ₂C₂Ph], 15, which are also isomers similar to 12 and 13. The reaction of 11 with PhC₂H in the presence of Pd(PBu ^t₃)₂ yielded the product PdRu(CO) ₄(SnPh₃)(PBu^t₃)[μ-H ₂C₂Ph], 16. Compound 16 contains a Pd(PBu^t ₃) group bonded to the ruthenium atom and a bridging H ₂C₂Ph ligand that is π-bonded to the palladium atom. Compound 10 reacted with Pt(PBu^t₃)₂ in the absence of PhC₂H to yield the compound PtOs(CO)₄(SnPh ₃)(PBu^t₃)(μ-H), 17. Compound 17 is a Pt(PBu^t₃) adduct of 10. It contains a Pt-Os bond with a bridging hydrido ligand. Compound 17 reacted with PhC₂H to yield 12. Compound 12 reacted with PhC₂H to yield the compound PtOs(CO) ₃(SnPh₃)(PBu^t₃)[μ-HCC(Ph)C(H)C(H) Ph], 18. Compound 18 contains a bridging 2,4-diphenylbutadienyl ligand, HCC(Ph)C(H)C(H)Ph, that is π-bonded to the osmium atom and σ-bonded to the platinum atom. Fenkse-Hall molecular orbitals of 17 were calculated. The LUMO of 17 exhibits an empty orbital on the platinum atom that appears to be the most likely site for PhC₂H addition prior to its insertion into the Os-H bond.

Full text of DOI:10.1021/ja070617h

Published on Web 05/26/2007
Activation of Metal Hydride Complexes by
Tri-tert-butylphosphine-Platinum and -Palladium Groups
Richard D. Adams,* Burjor Captain, Eszter Trufan, and Lei Zhu
Contribution from the Department of Chemistry and Biochemistry, UniVersity of South Carolina,
Columbia, South Carolina 29208
Received January 27, 2007; E-mail: Adams@mail.chem.sc.edu
Abstract: The compounds HM(CO)4SnPh3, M ) Os (10), Ru (11) are activated in the presence of Pt-
(PBut3)2 and Pd(PBut3)2 toward the insertion of PhC2H into the M-H bond. The compounds PtOs(CO)4-
(SnPh3)(PBut3)[µ-HCC(H)Ph], 12, and PtOs(CO)4(SnPh3)(PBut3)[µ-H2CCPh], 13, were obtained from the
reaction of 10 with PhC2H in the presence of Pt(PBut3)2. Compounds 12 and 13 are isomers containing
alkenyl ligands formed by the insertion of the PhC2H molecule into the Os-H bond at both the substituted
and unsubstituted carbon atoms of the alkyne. Both compounds contain a Pt(PBut3) group that is bonded
to the osmium atom and a bridging alkenyl ligand that is π-bonded to the osmium atom. The reaction of 11
with PhC2H in the presence of Pt(PBut3)2 yielded the products PtRu(CO)4(SnPh3)(PBut3)[µ-HC2(H)Ph], 14,
and PtRu(CO)4(SnPh3)(PBut3)[µ-H2C2Ph], 15, which are also isomers similar to 12 and 13. The reaction of
11 with PhC2H in the presence of Pd(PBut3)2 yielded the product PdRu(CO)4(SnPh3)(PBut3)[µ-H2C2Ph],
16. Compound 16 contains a Pd(PBut3) group bonded to the ruthenium atom and a bridging H2C2Ph ligand
that is π-bonded to the palladium atom. Compound 10 reacted with Pt(PBut3)2 in the absence of PhC2H to
yield the compound PtOs(CO)4(SnPh3)(PBut3)(µ-H), 17. Compound 17 is a Pt(PBut3) adduct of 10. It contains
a Pt-Os bond with a bridging hydrido ligand. Compound 17 reacted with PhC2H to yield 12. Compound 12
reacted with PhC2H to yield the compound PtOs(CO)3(SnPh3)(PBut3)[µ-HCC(Ph)C(H)C(H)Ph], 18. Com-
pound 18 contains a bridging 2,4-diphenylbutadienyl ligand, HCC(Ph)C(H)C(H)Ph, that is π-bonded to the
osmium atom and σ-bonded to the platinum atom. Fenkse-Hall molecular orbitals of 17 were calculated.
The LUMO of 17 exhibits an empty orbital on the platinum atom that appears to be the most likely site for
PhC2H addition prior to its insertion into the Os-H bond.
t
Introduction
also by the steric crowding produced by the PBu3 ligand which
inhibits a normal complement of supporting ligands.
In recent studies we have demonstrated the synthesis of a
variety of electronically unsaturated heteronuclear metal cluster
complexes by the addition of Pd(PBut3) and Pt(PBut3) groups
to the metal-metal bonds of transition metal carbonyl cluster
complexes.1-5 Some examples of these are the complexes
Ru3Pd3(CO)12(PBut3)3, 1,1a Ir4Pt2(CO)12(PBut3)2, 2,3 and Rh6-
Pt4(CO)16(PBut3)4, 3.5 The electronic unsaturation is created both
by the tendency of Pd and Pt to accommodate electron
configurations that are less than 18 electrons/metal atom and
(1) (a) Adams, R. D.; Captain, B.; Fu, W.; Hall, M. B.; Manson, J.; Smith, M.
D.; Webster, C. E. J. Am. Chem. Soc. 2004, 126, 5253-5267. (b) Adams,
R. D.; Captain, B.; Fu, W.; Smith, M. D. J. Am. Chem. Soc. 2002, 124,
5628-5629. (c) Adams, R. D.; Captain, B.; Zhu, L. Organometallics 2006,
45, 430-436. (d) Adams, R. D.; Captain, B.; Zhu, L. J. Cluster Sci. 2006,
17, 87-95.
(2) (a) Adams, R. D.; Captain, B.; Fu, W.; Pellechia, P. J.; Smith, M. D. Angew.
Chem., Int. Ed. 2002, 41, 1951-1953. (b) Adams, R. D.; Captain, B.; Fu,
W.; Pellechia, P. J.; Smith, M. D. Inorg. Chem. 2003, 42, 2094-2101. (c)
Adams, R. D.; Captain, B.; Fu, W.; Pellechia, P. J.; Zhu, L. Inorg. Chem.
2004, 43, 7243-7249.
(3) Adams, R. D.; Captain, B.; Hall, M. B.; Smith, J. L., Jr.; Webster, C. E. J.
Am. Chem. Soc. 2005, 127, 1007-1014.
(4) (a) Adams, R. D.; Captain, B.; Herber, R. H.; Johansson, M.; Nowik, I.;
Smith, J. L., Jr.; Smith, M. D. Inorg. Chem. 2005, 44, 6346-6358. (b)
Adams, R. D.; Captain, B.; Zhu, L. Organometallics 2006, 25, 2049-
2054.
(5) Adams, R. D.; Captain, B.; Pellechia, P. J.; Smith, J. L. Inorg. Chem. 2004,
43, 2695-2702.
9
10.1021/ja070617h CCC: $37.00 © 2007 American Chemical Society
J. AM. CHEM. SOC. 2007, 129, 7545-7556
7545

A R T I C L E S
Scheme 1a
Adams et al.
a Platinum (blue), rhenium (green), phosphorus (gold), oxygen (red), carbon (pink), hydrogen (gray).
Scheme 2a
t
a M(PBu3 ), M ) Pd or Pt, group that interacts with the hydrido
ligand in the complex prior to the addition/insertion of the alkyne
into the metal-hydrogen bond. In this first report, we describe
the results of our studies of the insertion of the alkyne,
phenylacetylene, PhC2H, into the M-H bonds of the compounds
HM(CO)4SnPh3, M ) Os (10), Ru (11). The insertion of alkynes
and alkenes into a metal-hydrogen bond is one of the most
basic steps in the process of catalytic hydrogenation through
which alkynes are converted to alkenes and alkenes are
converted to alkanes.9 In general, these reactions proceed by
the coordination of a substrate to a metal atom prior to a C-H
bond forming insertion step.9b A preliminary report of a portion
of this work has recently been published.10
a Platinum (blue), rhenium (green), phosphorus (gold), oxygen (red),
carbon (pink), hydrogen (gray).
We have also shown that the Pt(PBut3) group can be
integrated into the architecture of the metal cluster to produce
very highly unsaturated complexes that are capable of adding
hydrogen under very mild conditions. In some cases, this is
reversible.6-7 For example, the 62 electron complex Pt3Re2-
(CO)6(PBut3)3, 4, sequentially adds 3 equiv of H2 to form the
compounds Pt3Re2(CO)6(PBut3)3(µ-H)2, 5, Pt3Re2(CO)6(PBut3)3-
(µ-H)4, 6, and Pt3Re2(CO)6(PBut3)3(µ-H)6, 7, Scheme 1.6a Some
of the hydrogen is released from these hydride complexes when
they are irradiated with UV-vis radiation.
Experimental Section
General Data. All the reactions were performed under a nitrogen
atmosphere using the standard Schlenk techniques. Reagent grade
solvents were dried by the standard procedures and were freshly
distilled prior to use. Infrared spectra were recorded on an AVATAR
1
360 FT-IR spectrophotometer. H NMR and 31P NMR were recorded
on a Varian Mercury 400 spectrometer operating at 399 and 162 MHz,
respectively. 31P NMR spectra were externally referenced against 85%
ortho-H3PO4. Variable temperature 1H NMR and 31P NMR spectra were
recorded on a Varian Inova 500 operating at 500.2 and 202.5 MHz,
respectively. Elemental analyses were performed by Desert Analytics
(Tucson, AZ). Mass spectrometric measurements performed by a direct
exposure probe using electron impact ionization (EI) were made on a
VG 70S instrument. Triphenylstannane (Ph3SnH) and phenylacetylene
(PhC2H) were purchased from Aldrich and were used without further
purification. Ru3(CO)12, Pd(PBut3)2, and Pt(PBut3)2 were purchased from
STREM and were used without further purification. HOs(CO)4SnPh3,
10, was prepared according to the previously published procedure.11
Product separations were performed by TLC in air on Analtech 0.25
mm silica gel 60 Å F254 glass plates.
Synthesis of HRu(CO)4SnPh3, 11. A solution of Ru(CO)5 was
prepared and used in situ as follows.12 A 40 mg amount of Ru3(CO)12
(0.063 mmol) was dissolved in 120 mL of hexane in a 250 mL Pyrex
three-neck flask. The solution was placed in an ice bath and irradiated
using a medium-pressure mercury UV lamp (1000 W) in the presence
of a slow purge of carbon monoxide (CO) for approximately 25 min.
During this time the orange colored solution turned colorless. The
reaction flask was then evacuated and refilled with nitrogen to remove
the excess CO. A 79 mg amount of HSnPh3 (0.225 mmol) was then
added to the Ru(CO)5 solution at 0 °C. The solution was then heated
to reflux for 10 min during which time the colorless solution turned
Another example is the unsaturated dirheniumdiplatinum
t
complex Pt2Re2(CO)7(PBu3 )2(µ-H)2, 8, that adds 1 equiv of H2
at room temperature to yield the tetrahydrido complex Pt2Re2-
(CO)7(PBu3 )2(µ-H)4, 9, Scheme 2.7 The hydrogen addition to
t
8 can be reversed by both thermal and photochemical means;
see Scheme 2.
The adsorption and activation of hydrogen will be important
both to the storage and the utilization of hydrogen in energy
systems of the future.8
We have now found that Pd(PBut3)2 and Pt(PBut3)2 can
activate hydride containing metal carbonyl complexes toward
insertion of alkynes into a metal-hydrogen bond by generating
(6) (a) Adams, R. D.; Captain, B.; Beddie, C.; Hall, M. B. J. Am. Chem. Soc.
2007, 129, 986-1000. (b) Adams, R. D.; Captain, B. Angew. Chem., Int.
Ed. 2005, 44, 2531-2533.
(7) (a) Adams, R. D.; Captain, B.; Smith, M. D.; Beddie, C. L.; Hall, M. B. J.
Am. Chem. Soc. 2007, 129, 5981-5991. (b) Adams, R. D.; Captain, B.;
Smith, M. D. Angew. Chem., Int. Ed. 2006, 45, 1109-1112.
(8) (a) Crabtree, G. W.; Dresselhaus, M. S.; Buchanan, M. V. The Hydrogen
Economy. Physics Today 2004, 39-44. (b) Ogden, J. M. Hydrogen: The
Fuel of the Future? Physics Today 2002, 55, 69-75. (c) Schlapbach, L.;
Zu¨ttel, A. Nature 2001, 414, 353-358. (d) Zecchina, A.; Borgida, S.;
Vitillo, J. G.; Ricchiardi, G.; Lamberti, C.; Spoto, G.; Bjørgen, M.; Lillerud,
K. P. J. Am. Chem. Soc. 2005, 127, 6361-6366. (e) Nijkamp, M. G.;
Raaymakers, J. E. M. J.; van Dillen, A. J.; de Jong, K. P. Appl. Phys. A
2001, 72, 619-623. (f) Weitkamp, J.; Fritz, M.; Ernst, S. Int. J. Hydrogen
Energy 1995, 20, 967-970. (g) Rosi, N. L.; Eckert, J.; Eddaoudi, M.;
Vodak, D. T.; O’Keerre, M.; Yaghi, O. M. Science 2003, 300, 1127-
1129. (h) Zhao, X.; Xiao, B.; Fletcher, A. J.; Thomas, K. M.; Bradshaw,
D.; Rosseinsky, M. J. Science 2004, 306, 1012-1015. (i) Rowsell, J. L.
C.; Eckert, J.; Yaghi, O. M. J. Am. Chem. Soc. 2005, 127, 14904-14099.
(j) Dinca, M.; Long, J. R. J. Am. Chem. Soc. 2005, 127, 9376-9377. (k)
Kaye, S. S.; Long, J. R. J. Am. Chem. Soc. 2005, 127, 6506-6507. (l)
Sun, D.; Ma, S.; Ke, Y.; Collins, D. J.; Zhou, H.-C. J. Am. Chem. Soc.
2006, 128, 3896-3897.
(9) (a) Selmeczy, A. D.; Jones, W. D. Inorg. Chim. Acta 2000, 300-302, 138.
(b) Collman, J. P.; Hegedus, L. S.; Norton, J. R.; Finke, R. G. Principles
and Applications of Organotransition Metal Chemistry; University Science
Books: Mill Valley, CA, 1987; Chapter 10.
(10) Adams, R. D.; Captain, B.; Zhu, L. J. Am. Chem. Soc. 2006, 128, 13672-
13673.
(11) Adams, R. D.; Captain, B.; Zhu, L. Organometallics 2006, 25, 4183-
4187.
(12) Huq, R.; Poe¨, A. J.; Chawla, S. Inorg. Chim. Acta 1980, 38, 121-125.
9
7546 J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007

Metal Hydride Complex Activation by Pd-/Pt(PBut3)2 Groups
A R T I C L E S
bright yellow. After cooling, the solvent was removed in vacuo, and
the product was separated by TLC by using a 6:1 hexane-methylene
chloride solvent mixture to yield 52 mg (49%) of light yellow 11.
NOTE: The TLC separation should be performed quickly as HRu-
(CO)4SnPh3 decomposes on silica gel. Spectral data for 11: IR νCO
(cm-1 in CH2Cl2): 2120 (m), 2060 (m, sh), 2037 (vs). 1H NMR (CDCl3,
were assigned based on the 31P decoupled 1H NMR spectrum. Elemental
Anal. Calcd for 15: C, 47.43; H, 4.64. Found: C, 48.60; H, 4.46%.
Synthesis of PdRu(CO)4(SnPh3)(PBut3)[µ-H2CCPh], 16. A 16 mg
amount of Pd(PBut3)2 (0.031 mmol) was dissolved in 30 mL of CH2-
Cl2 in a 100 mL three-neck flask. Phenylacetylene (0.025 mL, 0.225
mmol) was added to the solution, and it was then heated to reflux for
20 min. To the refluxing solution, 20 mg of HRu(CO)4(SnPh3) (0.035
mmol) were added and stirred at reflux for another 10 min. The reaction
mixture was then cooled, and the solvent and the excess phenylacetylene
were removed in vacuo. The product was separated by TLC by using
a 6:1 hexane/methylene chloride solvent mixture to yield 5.0 mg (15%)
of yellow PdRu(CO)4(SnPh3)(PBut3)[µ-H2CCPh], 16. Spectral data for
16: IR νCO (cm-1 in CH2Cl2): 2078 (m), 2004 (vs), 1870 (w). 1H NMR
(CDCl3, in ppm): δ ) 7.20-7.70 (m, Ph), 6.87-6.93 (m, Ph), 6.55-
6.58 (m, Ph), 5.53 (dd, 1H, CH, 3JP-H ) 2 Hz, 2JH-H ) 2 Hz), 4.42 (d,
1H, CH, 2JH-H ) 2 Hz), 1.40 (d, CH3, 3JP-H ) 13 Hz). The resonance
at 5.53 appears as a triplet, but it is actually an overlapping doublet of
in ppm): δ ) 7.30 - 7.57 (m, 15 H, Ph), -7.66 (s, 1H, hydride, 2J119
Sn-H
2
) 51 Hz, J117
) 49 Hz). Elemental Anal. Calcd: C, 46.84; H,
Sn-H
2.86. Found: C, 46.99; H, 3.05%.
Preparation of PtOs(CO)4(SnPh3)(PBut3)[µ-HCC(H)Ph], 12, and
PtOs(CO)4(SnPh3)(PBut3)[µ-H2CCPh], 13. A 12.6 mg amount of 10
(0.020 mmol) and 14.2 mg amount of Pt(PBut3)2 (0.024 mmol) were
dissolved in 10 mL of CH2Cl2 in a 25 mL three-neck flask, and 2.6 µL
of phenylacetylene (0.024 mmol) was added by using a 10 µL
microsyringe. The solution was stirred at room temperature for 10 min.
The solvent was then removed in vacuo, and the product was separated
by TLC by using hexane solvent to yield 7.0 mg (31%) of PtOs(CO)4-
(SnPh3)(PBut3)[µ-HCC(H)Ph], 12, and 4.4 mg (19%) of PtOs(CO)4-
(SnPh3)(PBut3)[µ-H2CCPh], 13. Spectral data for 12: IR νCO (cm-1 in
CH2Cl2): 2049 (m), 2015 (m), 1977 (s); 1H NMR (toluene-d8 in ppm)
1
doublets. The 31P decoupled H NMR spectrum showed a doublet for
the resonance at 5.53 ppm indicating that this peak is coupled to both
31P and 1H, while the resonance at 4.42 ppm remained a doublet
1
indicating that this resonance is coupled only to H. 31P {1H} NMR
3
at - 65 °C: δ ) 9.25 (d, 1H, CH, JH-H ) 14 Hz), 9.01 (d, 2H, CH,
3
3
3
3JH-H ) 13 Hz), 8.89 (d, 1H, CH, JH-H ) 13 Hz, JPt-H ) 51 Hz),
(CDCl3, in ppm): δ ) 90.2 (s, 1P, JSn-P ) 76 Hz). Elemental Anal.
3
3
Calcd for 16: C, 51.64; H, 5.02. Found: C, 52.02; H, 5.23%.
Preparation of PtOs(CO)4(SnPh3)(PBut3)(µ-H), 17. A 27 mg
amount of 10 (0.042 mmol) was dissolved in 10 mL CH2Cl2 in a 50
mL three-neck flask. A 32 mg amount of Pt(PBut3)2 (0.053 mmol) was
added, and the reaction stirred at room temperature for 25 min. The
solvent was then removed in vacuo, and the product was purified by
TLC by using 6:1 hexane-methylene chloride solvent mixture to yield
18.2 mg (45%) of PtOs(CO)4(SnPh3)(PBut3)(µ-H), 17. Spectral data
for 17: IR νCO (cm-1 in CH2Cl2): 2124 (w), 2076 (vs), 2038 (w, sh),
6.02 (d, 1H, CH, JH-H ) 13 Hz), 5.87 (d, 1H, CH, JH-H ) 13 Hz),
3
3
5.73 (d, 1H, CH, JH-H ) 13 Hz), 4.82 (d, 1H, CH, JH-H ) 14 Hz);
at +60 °C: δ ) 1.12 (d, 27H, CH3, JP-H ) 13 Hz). 31P{1H} NMR
3
1
(toluene-d8 in ppm) at -50 °C: δ ) 93.0 (s, 1P, JPt-P ) 2952 Hz),
90.8 (s, 1P, JPt-P ) 2942 Hz, JSn-P ) 39 Hz), 90.1 (s, 1P, JPt-P
1
3
1
)
3226 Hz, 3JSn-P ) 20 Hz), 88.0 (s, 1P, JPt-P ) 2910 Hz, 3JSn-P ) 20
Hz). Spectral data for 13: IR νCO (cm-1 in CH2Cl2): 2060 (m), 2013
(m), 1980 (s); 1H NMR (CD2Cl2 in ppm): δ ) 4.82 (d, 1H, CH, 3JH-H
) 1.6 Hz, 3JPt-H ) 135 Hz, 3JSn-H ) 26 Hz), 2.81 (dd, 1H, CH, 2JH-H
) 1.6 Hz, 4JP-H ) 1.6 Hz). 31P{1H} NMR (CD2Cl2 in ppm): δ ) 98.5
(s, 1P, 1JPt-P ) 3046 Hz). Anal. Calcd: C, 43.75; H, 4.25. Found: C,
43.58; H, 4.12%.
1
1
2010 (vs), 1809 (m). H NMR (CD2Cl2 in ppm): δ ) 1.34 (d, 27H,
3
2
1
CH3, JP-H ) 13 Hz), -5.99 (d, H, hydride, JP-H ) 46 Hz, JPt-H
)
2
2
566 Hz, J119
) 46 Hz, J117
) 44 Hz). 31P{1H} NMR (CD2Cl2
Sn-H
Sn-H
in ppm): δ ) 101.8 (s, 1P, 1JPt-P ) 6437 Hz). Elemental Anal. Calcd
for 17: C, 38.86; H, 4.10. Found: C, 38.96; H, 4.14%.
Reaction of 11 with Pt(PBut3)2. Synthesis of PtRu(CO)4(SnPh3)-
(PBut3)[µ-HCC(H)Ph], 14, and PtRu(CO)4(SnPh3)(PBut3)[µ-H2CCPh],
15. A 21.3 mg amount of Pt(PBut3)2 (0.035 mmol) was dissolved in
30 mL of CH2Cl2 in a 100 mL three-neck flask. Phenylacetylene (0.025
mL, 0.225 mmol) was added to the solution, and it was then heated to
reflux for 20 min. To the refluxing solution, 20 mg of HRu(CO)4(SnPh3)
(0.035 mmol) were added and stirred at reflux for another 10 min. The
reaction mixture was then cooled, and the solvent and the excess
phenylacetylene were removed in vacuo. The products were separated
by TLC using a 6:1 hexane/methylene chloride solvent mixture to yield
in order of elution: 2.0 mg (5%) of yellow PtRu(CO)4(SnPh3)(PBut3)[µ-
H2CCPh], 15, and 12.6 mg (33%) of light yellow PtRu(CO)4(SnPh3)-
(PBut3)[µ-HCC(H)Ph], 14. Spectral data for 14: IR νCO (cm-1 in
CH2Cl2): 2047 (s), 2014 (vs), 1972 (vs). 1H NMR (toluene-d8, in ppm)
at 25 °C: δ ) 9.29 (d, 1H, CH, 3JH-H ) 14 Hz, isomer 1), 9.17 (broad,
1H, CH, isomer 2), 6.82 - 8.00 (m, 15H, Ph), 5.94 (broad, 1H, CH,
Addition of PhC2H to 17. A 14.8 mg amount of 17 (0.014 mmol)
was dissolved in 10 mL of CH2Cl2 in a 50 mL three-neck flask. A 1.7
µL amount of PhC2H (0.014 mmol) was added, and the reaction solution
was stirred at room temperature for 15 min. The solvent was removed
in Vacuo, and the products were separated by TLC by using hexane
solvent to elute. This yielded 4.5 mg (28% yield) of 12 and 2.7 mg
(17% yield) of 13.
Preparation of PtOs(CO)3(SnPh3)(PBut3)[µ-HCC(Ph)C(H)C(H)-
Ph], 18. A 9.0 mg amount of 12 (0.0078 mmol) was dissolved in 10
mL of CH2Cl2 solvent in a 50 mL three-neck flask. A 10 µL amount
of PhC2H (0.094 mmol) was added, and the solution was heated to
reflux for 60 min. The solvent was removed in Vacuo, and the product
was purified by TLC using a 6:1 hexane/methylene chloride solvent
mixture to yield 4.7 mg (48%) of PtOs(CO)3(SnPh3)(PBut3)[µ-HCC-
(Ph)C(H)C(H)Ph], 18. Spectral data for 18: IR νCO (cm-1 in CH2Cl2):
3
isomer 2), 5.70 (broad, 1H, CH, isomer 1), 1.10 (d, CH3, JP-H ) 13
1
Hz). 31P {1H} NMR (CDCl3, in ppm) at 25 °C: δ ) 100.0 (s, 1P,
2020 (vs), 1980 (s), 1933 (m). H NMR (in CD2Cl2): δ ) 1.34 (d,
3
2
1JPt-P ) 2887 Hz). 1H NMR (toluene-d8, in ppm) at -40 °C: 9.30 (d,
27H, CH3, JP-H ) 13 Hz), 8.85, (s, 1H, CH, JPt-H ) 33 Hz), 7.13-
3
3
3
7.39 (m, 25H, Ph), 6.87 (d, 1H, CH, JH-H ) 9.8 Hz), 4.92 (d, 1H,
1H, CH, JH-H ) 14 Hz, isomer 1), 9.16 (d, 1H, CH, JH-H ) 14 Hz,
CH, JH-H ) 9.8 Hz). 31P{1H} NMR (in CD2Cl2): δ ) 98.5 (s, 1P,
3
3
isomer 2), 5.94 (d, 1H, CH, JH-H ) 14 Hz, isomer 2), 5.83 (d, 1H,
CH, JH-H ) 14 Hz, isomer 1). Elemental Anal. Calcd 14‚1.5C6H6:
1JPt-P ) 3045 Hz, JSn-P ) 27 Hz). Mass Spectrum: EI-MS showed
3
3
the parent ion at m/z 1226.
C, 51.87; H, 4.95. Found: C, 51.49; H, 4.60%. Spectral data for 15:
1
IR νCO (cm-1 in CH2Cl2): 2058 (m), 2009 (s), 1988 (vs). H NMR
Crystallographic Analysis. Orange crystals of 11 suitable for
diffraction analysis were grown from solutions in hexane solvent under
nitrogen by cooling to -80 °C. Colorless crystals of 12 suitable for
diffraction analysis were grown by slow evaporation of solvent from a
CH2Cl2/hexane solution at room temperature. Light yellow crystals of
13 and 18 suitable for diffraction analysis were grown by slow
evaporation of solvent from solutions in CH2Cl2/hexane solvent mixtures
at -20 °C. Yellow crystals of 14 suitable for diffraction analysis were
grown by slow evaporation of solvent from a solution in a benzene/
(CDCl3, in ppm): δ ) 7.10-7.74 (m, 15 H, Ph), 4.51 (br, 1H, CH,
3JPt-H ) 129 Hz, 3JSn-H ) 24 Hz), 2.80 (dd, 1H, CH, 4JP-H ) 2.9 Hz,
2JH-H ) 1.4 Hz), 1.30 (d, CH3, 3JP-H ) 13 Hz). 31P {1H} NMR (CDCl3,
1
3
in ppm): δ ) 137.5 (s, 1P, JPt-P ) 3158 Hz, JSn-P ) 75 Hz). The
resonance at 4.51 ppm appears as a broad singlet due to coupling to
31P and 1H. The 13P decoupled 1H NMR spectrum resolved this
resonance to a doublet with 2JH-H ) 1.4 Hz. The respective couplings
4
2
of JP-H ) 2.9 Hz and JH-H ) 1.4 Hz for the resonance at 2.80 ppm
9
J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007 7547

A R T I C L E S
Adams et al.
Table 1. Crystallographic Data for Compounds 11, 12, and 13
compound
11
12
13
empirical formula
formula weight
crystal system
lattice parameters
a (Å)
RuSnO4C22H16
564.11
triclinic
Pt2Os2P2O8C84H98
2305.52
triclinic
PtOsPO4C42H49
1152.76
triclinic
9.6568(5)
10.8775(5)
11.3053(6)
67.830(1)
89.132(1)
83.812(1)
1092.91(10)
P1h (#2)
2
1.714
1.856
294(2)
56.6
4327
257
1.047
0.001
0.0304, 0.0686
multi-scan
1.000/0.837
0.795
15.2610(15)
15.4146(15)
21.044(2)
76.544(2)
73.541(2)
76.415(2)
4540.8(8)
P1h (#2)
2
1.686
6.480
294(2)
56.6
16059
935
1.051
0.002
0.0405, 0.1230
multi-scan
1.000/0.430
3.731
10.3198(4)
12.1676(5)
18.4225(8)
78.148(1)
78.187(1)
65.989(1)
2048.97(15)
P1h (#2)
2
1.868
7.181
294(2)
56.8
16059
468
1.031
0.002
0.0270, 0.0628
multi-scan
1.000/0.430
1.646
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z value
F
calcd (g/cm3)
µ (Mo KR) (mm-1
temperature (K)
2Θmax (deg)
)
no. obsd (I > 2σ(I))
no. parameters
goodness of fit GOFa
max shift in cycle
residuals:a R1, wR2
absorption correction,
max/min
largest peak in final diff
map (e-/Å3)
2
a R ) Σhkl(||Fobsd| - |Fcalcd||)/Σhkl|Fobsd|; Rw ) [Σhklw(|Fobsd| - |Fcalcd|)2/ΣhklwFobsd
]
1/2, w ) 1/σ2(Fobsd); GOF ) [Σhklw(|Fobsd| - |Fcalcd|)2/(ndata - nvari)]1/2
.
octane solvent mixture at 8 °C. Yellow crystals of 15, orange crystals
of 16, and light yellow crystals of 17, suitable for diffraction analysis,
were grown by slow evaporation of solvent from solutions in CH2Cl2/
hexane solvent mixtures at 8 °C. Each data crystal was glued onto the
end of a thin glass fiber. X-ray intensity data were measured by using
a Bruker SMART APEX CCD-based diffractometer using Mo KR
radiation (λ ) 0.710 73 Å). The raw data frames were integrated with
the SAINT+ program by using a narrow-frame integration algorithm.13
Correction for the Lorentz and polarization effects were also applied
by SAINT. An empirical absorption correction based on the multiple
measurement of equivalent reflections was applied by using the program
SADABS. All three structures were solved by a combination of direct
methods and difference Fourier syntheses and refined by full matrix
least-squares on F2, by using the SHELXTL software package.14 Crystal
data, data collection parameters, and results of the analyses for
compounds 11-18 are listed in Tables 1-3.
Compounds 11-16 and 18 all crystallized in the triclinic crystal
system. The space group P1h was assumed and confirmed in each case
by the successful solution and refinement of the structure. All non-
hydrogen atoms were refined with anisotropic thermal parameters.
Hydrogen atoms on the tert-butyl groups and phenyl groups were placed
in geometrically idealized positions and refined as standard riding atoms.
The hydrogen atoms on the phenylacetylene ligand in all compounds
were located in difference Fourier maps and were refined with isotropic
thermal parameters. The hydride ligand in compound 11 was located
in a difference Fourier map and was refined satisfactorily with an
isotropic thermal parameter. For compound 12 there are two formula
equivalents of the molecule in the asymmetric unit. For compound 14
one and a half solvent molecules of benzene cocrystallized with the
complex. The solvent molecule was refined with isotropic thermal
parameters.
a fixed isotropic thermal parameter. All non-hydrogen atoms were
refined with anisotropic thermal parameters. Hydrogen atoms on the
tert-butyl groups were placed in geometrically idealized positions and
included as standard riding atoms.
Molecular Orbital Calculations. All molecular orbital cal-
culations reported herein were performed by using the Fenske-Hall
method.15 The calculations were performed utilizing a graphical
user interface developed16 to build inputs and view outputs from
stand-alone Fenske-Hall and MOPLOT2 binary executables.17
Contracted double-ú basis sets were used for the Os 5d, Pt 5d, Sn 5p,
P 3p, and C and O 2p atomic orbitals. Hydrogen was used in place of
both phenyl and tert-butyl groups in these calculations. The Fenske-
Hall scheme is a nonempirical approximate method that is capable
of calculating molecular orbitals for very large transition metal
systems and has built-in fragment analysis routines that allow one to
assemble transition metal cluster structures from ligand-containing
fragments.
Results and Discussion
No reaction was observed when a solution of 10 and PhC2H
was heated to reflux in toluene solvent for a period of 1 h.
However, when Pt(PBut3)2 was added to a similar solution of
10 and PhC2H in CH2Cl2 solvent, a rapid reaction occurred at
room temperature. Two products PtOs(CO)4(SnPh3)(PBut3)[µ-
HCC(H)Ph], 12, and PtOs(CO)4(SnPh3)(PBut3)[µ-H2CCPh], 13,
were obtained and isolated in 31% and 19% yields, respectively.
Both compounds were characterized by IR, 1H NMR, elemental
analyses, and single-crystal X-ray diffraction analyses. The two
(15) (a) Hall, M. B.; Fenske, R. F. Inorg. Chem. 1972, 11, 768-775. (b) Webster,
C. E.; Hall, M. B. In Theory and Applications of Computational
Chemistry: The First Forty Years; Dykstra, C., Ed.; Elsevier: Amsterdam,
2005; Chapter 40, pp 1143-1165.
(16) Manson, J.; Webster, C. E.; Hall, M. B. JIMP, development version 0.1.v117
(built for Windows PC and Redhat Linux); Department of Chemistry, Texas
A&M University: College Station, TX; http:// www.chem.tamu.edu/jimp/,
accessed July 2004.
Compound 17 crystallized in the monoclinic crystal system. The
space group P21/n was confirmed on the basis of the systematic
absences in the data. The hydrido ligand was located and refined with
(13) SAINT+, version 6.2a. Bruker Analytical X-ray System, Inc.: Madison,
Wisconsin, U.S.A., 2001.
(14) Sheldrick, G. M. SHELXTL, version 6.1; Bruker Analytical X-ray Systems,
Inc.: Madison, Wisconsin, U.S.A., 1997.
(17) Lichtenberger, D. L. MOPLOT2 for orbital and density plots from linear
combinations of Slater or Gaussian type orbitals, version 2.0; Department
of Chemistry, University of Arizona: Tucson, AZ, 1993.
9
7548 J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007

Metal Hydride Complex Activation by Pd-/Pt(PBut3)2 Groups
A R T I C L E S
Table 2. Crystallographic Data for Compounds 14, 15, and 16
compound
14
15
16
empirical formula
formula weight
crystal system
lattice parameters
a (Å)
PtRuSnPO4C42H49·3/2C6H6
1180.79
triclinic
PtRuSnPO4C42H49
1063.63
triclinic
PdRuSnPO4C42H49
974.94
triclinic
12.9837(3)
13.3071(3)
14.9483(4)
98.206(1)
90.739(1)
104.088(1)
2476.31(10)
P1h (#2)
2
1.584
3.692
294(2)
56.6
9883
503
1.039
0.001
0.0339, 0.0773
multi-scan
1.000/0.754
1.174
10.3182(2)
12.2019(3)
18.4334(4)
78.227(1)
78.186(1)
66.084(1)
2057.51(8)
P1h (#2)
2
1.717
4.433
294(2)
56.6
8334
468
1.024
0.002
0.0322, 0.0638
multi-scan
1.000/0.828
1.136
11.5256(5)
12.7825(6)
17.0037(8)
101.212(1)
106.474(1)
103.063(1)
2248.67(18)
P1h (#2)
2
1.440
1.349
294(2)
56.6
8009
468
1.042
0.001
0.0469, 0.1532
multi-scan
1.000/0.580
1.707
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z value
F
calcd (g/cm3)
µ (Mo KR) (mm-1
temperature (K)
2Θmax (deg)
)
no. obsd (I > 2σ(I))
no. parameters
goodness of fit GOFa
max. shift in cycle
residuals:a R1, wR2
absorption correction,
max/min
largest peak in final diff
map (e-/Å3)
2
a R ) Σhkl(||Fobsd| - |Fcalcd||)/Σhkl|Fobsd|; Rw ) [Σhklw(|Fobsd| - |Fcalcd|)2/ΣhklwFobsd
]
1/2, w ) 1/σ2(Fobsd); GOF ) [Σhklw(|Fobsd| - |Fcalcd|)2/(ndata - nvari)]1/2
.
Table 3. Crystallographic Data for Compounds 17 and 18
compound
17
18
empirical formula
formula weight
crystal system
lattice parameters
a (Å)
PtOsPO4C34H43
1050.63
monoclinic
PtOsSnPO3C49H55
1226.88
triclinic
15.3785(8)
12.0732(6)
20.6568(10)
90
108.841(1)
90
3629.8(3)
P21/n (#14)
4
1.923
8.096
294(2)
56.7
6971
391
1.031
0.002
0.0376, 0.0961
multi-scan
1.000/0.757
3.068
9.9318(3)
12.0190(3)
19.9237(5)
94.884(1)
91.471(1)
106.541(1)
2268.49(11)
P1h (#2)
2
1.796
6.490
294(2)
56.6
8777
526
1.065
0.005
0.0381, 0.0753
multi-scan
1.000/0.430
1.436
b (Å)
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
space group
Z value
F
calcd (g/cm3)
µ (Mo KR) (mm-1
temperature (K)
2Θmax (deg)
)
no. obsd (I > 2σ(I))
no. parameters
Figure 1. An ORTEP diagram of the molecular structure of 12 showing
30% probability thermal ellipsoids. Selected bond distances (in Å) are as
follows: (molecule 1) Pt(1)-Os(1) ) 2.7198(4), Pt(1)-C(1) ) 2.012(6),
Os(1)-C(1) ) 2.246(7), Os(1)-C(2) ) 2.364(6), Pt(1)-P(1) ) 2.3446-
(17), Os(1)-Sn(1) ) 2.6921(5); (molecule 2) Pt(2)-Os(2) ) 2.7177(4),
Pt(2)-C(3) ) 2.017(6), Os(2)-C(3) ) 2.243(7), Os(2)-C(4) ) 2.375(6),
Pt(2)-P(2) ) 2.3432(17), Os(2)-Sn(2) ) 2.6840(5), C(1)-C(2) ) 1.409-
(10), C(3)-C(4) ) 1.392(9), Sn(1)-Os(1) - Pt(1) ) 165.184(17), Sn-
(2)-Os(2)-Pt(2) ) 163.966(15).
goodness of fit GOFa
max shift in cycle
residuals:a R1, wR2
absorption correction,
max/min
largest peak in final diff
map (e-/Å3)
a R ) Σhkl(||Fobsd| - |Fcalcd||)/Σhkl|Fobsd|; Rw ) [Σhklw(|Fobsd| - |Fcalcd|)2/
2.7177(4) Å] (molecule 2). There is an η2-bridging HCC(H)Ph
ligand that is σ-bonded to the platinum atom, Pt(1)-C(1) )
2.012(6) Å [Pt(2)-C(3) ) 2.017(6) Å] and π-bonded to the
osmium atom: Os(1)-C(1) ) 2.246(7) Å, Os(1)-C(2) ) 2.364-
(6) Å and [Os(2)-C(3) ) 2.243(7) Å, Os(2)-C(4) ) 2.375(6)
Å] (molecule 2). The C-C bond distance for the alkenyl ligand
is C(1)-C(2) ) 1.409(10) Å and [C(3)-C(4) ) 1.392(9) Å].
This is similar to the C-C bond distance of 1.38(4) Å found
for the alkenyl ligand in the compound HOs3(CO)10(HCC(H)-
But)18a and for alkenyl ligands in related complexes.18b The
SnPh3 ligand on the osmium atom is positioned trans to the Pt
2
Σ
hklwFobsd
]
1/2, w ) 1/σ2(Fobsd); GOF ) [Σhklw(|Fobsd| - |Fcalcd|)2/(ndata
-
n
vari)]1/2
.
products are isomers formed by the addition of 1 equiv of PhC2H
and 1 equiv of Pt(PBut3) to 10. There are two crystallographi-
cally independent molecules in the asymmetric crystal unit of
12. Both molecules are structurally similar. An ORTEP diagram
of the molecular structure of one of the two independent
molecules of 12 is shown in Figure 1. The platinum atom is
bonded to the osmium atom at a normal bonding distance, Pt-
(1)-Os(1) ) 2.7198(4) Å (molecule 1) and [Pt(2)-Os(2) )
9
J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007 7549

A R T I C L E S
Adams et al.
Scheme 3
three doublets of varying intensities in the region 8.5-9.5 ppm.
These can be assigned to the proton H(2) of the four isomers
of 12, cf. Figure 1. Although there should be four doublets for
the four isomers, this can be explained by an accidental shift
equivalence of two sets of doublets at 9.01 ppm. This is
confirmed by the spectrum recorded at -25 °C where the
resonance at 9.01 has been split into two overlapping doublets
as a result of different temperature dependent changes in the
chemical shifts of the two doublets that were superimposed at
9.01 ppm at -65 °C. Over the temperature range -65 °C to
+110 °C three dynamical averaging processes are observed.
At 0 °C two pairs of doublets in the 4.8-6.2 ppm and 8.5-9.5
ppm regions of the spectrum exhibit broadening due to
dynamical exchange. These pairs of resonances have averaged
in their respective regions at +60 °C. At about 40 °C, another
pair of doublets, one in the 4.8-6.2 ppm region and one in the
8.5-9.5 ppm region from a third isomer, begins to broaden and
ultimately averages with the resonances of the other averaging
isomers at higher temperatures. Finally, at about 60 °C, the
fourth pair of doublets begins to broaden (this is clear at
+80 °C) and then averages with the average of the resonances
of the other three isomers. The temperature dependent changes
are fully reversible. At +110 °C, the resonances in each of the
two regions have averaged completely. The averaged doublet
at 9.1 ppm is sharp, but due to the greater chemical shift
differences between the resonances, the averaged resonance at
about 5.4 ppm has not fully sharpened yet at 110 °C which is
the highest temperature at which we could record in the toluene-
d8 solvent that was used for this sample. It is proposed that the
four isomers of 12, 12a-12d, consist of the one found in the
solid state shown in Figure 1 and three others formed by
interchanging the SnPh3 group with each of the three terminal
CO ligands on the osmium atom. Specific assignments cannot
be made. These four isomers can be interchanged at three
different rates (as observed) simply by performing internal
rotations of the entire Pt(1)-C(1)-C(2) group to four different
rotational orientations each ∼90° apart with respect to the Os-
(CO)3(SnPh3) group; see Scheme 3. Slight angle deformations
occur between the SnPh3 and CO ligands during these rotations,
but this would not introduce any significant barriers. The Pt-
(1)-C(1)-C(2) group could be viewed as a π-bonded metal-
laallyl fragment. Internal rotations of π-allyl ligands are well
documented.19 The resonances of the tert-butyl methyl reso-
nances (not shown in Figure 2) are complex throughout the low-
Figure 2. Variable temperature 1H NMR spectra for compound 12 in
toluene-d8 solvent. Resonance of the phenyl protons (6.6-8.3 ppm) have
been removed for clarity.
atom, Sn(1)-Os(1)-Pt(1) ) 165.184(17)° [Sn(2)-Os(2)-Pt-
(2) ) 163.966(15)°]. The Os-Sn distance, Os(1)-Sn(1) )
2.6921(5) Å [Os(2)-Sn(2) ) 2.6840(5) Å] is slightly shorter
than that found in 10, 2.7382(2) Å.11
The 1H NMR spectra of 12 at -65 °C indicates that it exists
in solution as a mixture of four isomers. At room temperature
1
the isomers are interconverting rapidly on the H NMR time
1
scale. A stacked plot of the variable temperature H NMR
spectra of the two alkenyl protons of 12 in the region 4.8-9.5
ppm is shown in Figure 2. The region of the resonances of the
phenyl protons (6.6-8.3 ppm) has been removed for clarity.
At -65 °C, there are four doublets of varying intensities in the
region 4.8-6.2 ppm. These resonances are assigned to the
alkenyl proton H(1), cf. Figure 1. One doublet corresponds to
each of four isomers in solution. At -65 °C, there are another
(18) (a) Sappa, E.; Tiripicchio, A.; Lanfredi, A. M. M. J. Organomet. Chem.
1975, 249, 391-404. (b) Deeming, A. J. AdV. Organomet. Chem. 1986,
26, 1-96.
(19) Davison, A.; Rode, W. C. Inorg. Chem. 1967, 6, 2124-2125.
9
7550 J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007

Metal Hydride Complex Activation by Pd-/Pt(PBut3)2 Groups
A R T I C L E S
Figure 3. ORTEP diagram of the molecular structure of 13 showing 40%
probability thermal ellipsoids. Selected bond distances (Å) and angles (deg)
are as follows: Pt(1)-Os(1) ) 2.7114(2), Pt(1)-P(1) ) 2.3575(9), Pt-
(1)-C(21) ) 2.023(4), Os(1)-C(21) ) 2.300(4), Os(1)-C(20)) 2.300-
(4), Os(1)-Sn(1) ) 2.6743(3), C(20)-C(21) ) 1.403(6); Sn(1)-Os(1)-
Pt(1) ) 153.704(9).
Figure 4. An ORTEP diagram of the molecular structure of 11 showing
30% probability thermal ellipsoids. Selected bond distances (in Å) are as
follows: Ru(1)-Sn(1) ) 2.7108(3), Ru(1)-H(1) ) 1.63(4), Sn(1)-C(20)
) 2.148(3), Sn(1)-C(26) ) 2.157(3), Sn(1)-C(32) ) 2.156(3).
temperature range due to hindered internal rotations of the tert-
butyl groups about the P-C bonds, but at +60 °C a single
doublet is observed, as expected for the average of the four
isomers.
The HC2(H)Ph ligand in 12 was formed by the insertion of
the PhC2H molecule into the Os-H bond with transfer of the
hydrogen atom to the phenyl-substituted carbon atom of the
alkyne. Note the E-stereochemistry of the alkenyl ligand which
is consistent with cis insertion of the alkyne via the classical
four-center transition state.9 In the course of the PhC2H addition,
one CO ligand from 10 was shifted from the osmium atom to
the platinum atom. The osmium atom in 12 contains 18 valence
electrons; the platinum atom has only 16.
diffraction analysis. An ORTEP diagram of the molecular
structure of 11 is shown in Figure 4. Compound 11 is
structurally similar to 10. The ruthenium atom contains four
terminal carbonyl ligands. The SnPh3 ligand and terminal
hydrido ligand occupy cis-coordination sites in the six-
coordinate complex. The Ru-H distance, 1.63(4) Å, is similar
to the Os-H distance in 10, 1.67(4) Å.11 The hydrido ligand
exhibits the expected high field proton resonance shift in the
1H NMR spectrum δ ) -7.66 with coupling to the tin atom,
2
2J119
) 51 Hz, J117
) 49 Hz.
Sn-H
Sn-H
An ORTEP diagram of the molecular structure of 13 is shown
in Figure 3. The structure of 13 is very similar to that of 12.
There is a platinum-osmium bond that is only slightly shorter
than that in 12, Pt(1)-Os(1) ) 2.7114(4) Å. There is also an
η2-bridging alkenyl ligand, this time with the formula PhCCH2,
that is σ-bonded to the platinum atom, Pt(1)-C(21) ) 2.023-
(4) Å, and π-bonded to the osmium atom, Os(1)-C(21) )
2.300(4) Å, Os(1)-C(20) ) 2.300(4) Å. The C-C bond
distance, C(20)-C(21) ) 1.403(6) Å, is similar to that in 12.
The SnPh3 ligand on the Os atom is also positioned trans to
the Pt atom, Sn(1)-Os(1)-Pt(1) ) 153.704(9)°. The Os-Sn
distance in 13, Os(1)-Sn(1) ) 2.6743(3) Å, is similar to that
found in 12. The 1H NMR spectra of 13 are consistent with the
structure found in the solid state indicating the presence of only
Like 10, compound 11 does not react with PhC2H at
temperatures less than 68 °C, where it begins to decompose.
However, in the presence of Pt(PBut3)2, there is a rapid reaction
at room temperature to yield two new compounds: PtRu(CO)4-
(SnPh3)(PBut3)[µ-HCC(H)Ph], 14, and PtRu(CO)4(SnPh3)-
(PBut3)[µ-H2CCPh], 15, in the yields 33% and 5%, respectively.
Compounds 14 and 15 have been shown to be the Ru
1
homologues of 12 and 13 by a combination of IR, H NMR,
and single-crystal X-ray diffraction analyses. ORTEP diagrams
of the molecular structures of 14 and 15 are shown in Figures
5 and 6, respectively.
The molecular structure of 14 is similar to that of 12, except
that the SnPh3 ligand on the Ru atom is positioned cis to the Pt
atom, Sn(1)-Ru(1)-Pt(1) ) 101.098(12)°. This structure would
correspond to the solution isomer 12c proposed for 12. The Ru-
Sn bond distance, Ru(1)-Sn(1) ) 2.6585(4) Å, is significantly
shorter than that in 11, 2.7108(3) Å. The Pt-Ru bond distance,
Pt(1)-Ru(1) ) 2.6981(3) Å, is only slightly shorter than the
Pt-Os bond distance in 12. Compound 14 was formed by the
insertion of the PhC2H molecule into the Os-H bond with
transfer of the hydrido ligand to the phenyl-substituted carbon
atom. The Pt-C and Ru-C distances to the bridging HC2(H)-
Ph ligand are very similar to those found in 12: Pt(1)-C(1) )
2.022(4) Å, Ru(1)-C(1) ) 2.239(4) Å, and Ru(1)-C(2) )
2.377(4) Å. Like 12, compound 14 also exists in solution, as a
mixture of interconverting isomers. This was demonstrated by
one isomer in solution. The small two bond coupling, 2JH-H
)
1.6 Hz, between the two resonances at δ ) 4.82 and 2.81 is
consistent with the presence of the two hydrogen atoms on the
same carbon atom C(20) of the PhCCH2 ligand. The PhCCH2
ligand could be formed by insertion of the PhC2H molecule
into the Os-H bond by a mechanism analogous to that which
yielded 12, except that the hydrogen atom would be transferred
instead to the unsubstituted carbon atom of the alkyne; see below
for further discussion of the mechanism.
For comparative purposes, the reactions of HRu(CO)4SnPh3,
11, with PhC2H in the presence and absence of Pt(PBut3)2 were
also investigated. The new compound 11 was obtained in 49%
yield from the reaction of Ru(CO)5 with HSnPh3 by heating a
solution in hexane solvent to reflux for 10 min. Compound 11
1
the variable temperature H NMR spectra that are shown in
Figure 7. These spectral changes can be explained by the
presence of isomers with dynamical interconversions similar
1
was characterized by IR, H NMR, and single-crystal X-ray
9
J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007 7551

A R T I C L E S
Adams et al.
Figure 5. ORTEP diagram of the molecular structure of 14 showing 30%
probability thermal ellipsoids. Selected bond distances (in Å) and angles
(deg) are as follows: Pt(1)-Ru(1) ) 2.6981(3), Pt(1)-P(1) ) 2.3542(10),
Pt(1)-C(1) ) 2.022(4), Ru(1)-C(1) ) 2.239(4), Ru(1)-C(2) ) 2.377(4),
Ru(1)-Sn(1) ) 2.6585(4), C(1)-H(1) ) 1.04(4), C(2)-H(2) ) 0.90(4);
Sn(1)-Ru(1)-Pt(1) ) 101.098(12).
Figure 6. ORTEP diagram of the molecular structure of 15 showing 30%
probability thermal ellipsoids. Selected bond distances (in Å) and angles
(deg) are as follows: Pt(1)-Ru(1) ) 2.7068(4), Pt(1)-P(1) ) 2.3573(10),
Pt(1)-C(2) ) 2.023(4), Ru(1)-C(1) ) 2.292(4), Ru(1)-C(2) ) 2.298(4),
Ru(1)-Sn(1) ) 2.6612(4), C(1)-H(1) ) 0.90(4), C(1)-H(2) ) 1.10(4);
Sn(1)-Ru(1)-Pt(1) ) 153.786(16).
to those shown for 12 in Scheme 1, but their relative amounts
are different from those found for 12. Specific assignments
cannot be made at this time.
Figure 7. Variable temperature 1H NMR spectra for compound 14 in
toluene-d8 solvent. Resonance of the phenyl protons (6.4-8.2 ppm) have
been removed for clarity.
Compound 15 is an isomer of 14. It is structurally similar to
13. The Pt-Ru and Ru-Sn bond distances are similar to those
in 14, Pt(1)-Ru(1) ) 2.7068(4) Å, Ru(1)-Sn(1) ) 2.6612(4)
Å. The SnPh3 ligand lies approximately trans to the Pt atom,
Sn(1)-Ru(1)-Pt(1) ) 153.786(16)°. Compound 15 was formed
by the insertion of the PhC2H molecule into the Ru-H bond
with transfer of the hydrido ligand to the unsubstituted carbon
atom. Both hydrogen atoms on the alkenyl carbon atom C(1)
were located and refined in the structural analysis. They were
also confirmed at C(1) by 1H NMR spectroscopy by the
observation of their resonances at δ ) 4.51 and 2.80 ppm. The
resonance at 4.51 ppm appears as a broad singlet due to small
couplings to 31P from the phosphine ligand and the other
The reaction of 11 with PhC2H in the presence of Pd(PBut3)2
was also investigated. Only one alkyne addition product was
obtained, PdRu(CO)4(SnPh3)(PBut3)[µ-H2CCPh], 16 (15% yield),
when a solution of 11 with PhC2H and Pd(PBut3)2 in methylene
chloride solvent was heated to reflux for 10 min. Compound
1
16 was characterized by a combination of IR, H NMR, and
single-crystal X-ray diffraction analyses. An ORTEP diagram
of the molecular structure of 16 is shown in Figure 8. Compound
16 was formed by the addition and insertion of 1 equiv of PhC2H
into the Ru-H bond of 12 with transfer of the hydrogen atom
to the unsubstituted carbon atom of the alkyne. Pd(PBut3) (1
equiv) was also added to the complex, but unlike the H2C2Ph
ligands in 13 and 15, the bridging H2C2Ph ligand in 16 is
4
2
hydrogen atom on C(1), JP-H ) 2.9 Hz and JH-H ) 1.4 Hz.
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Metal Hydride Complex Activation by Pd-/Pt(PBut3)2 Groups
A R T I C L E S
Figure 8. ORTEP diagram of the molecular structure of 16 showing 30%
probability thermal ellipsoids. Selected bond distances (in Å) and angles
(deg) are as follows: Pd(1)-Ru(1) ) 2.7122(5), Pd(1)-P(1) ) 2.3681-
(13), Pd(1)-C(2) ) 2.250(5), Pd(1)-C(1) ) 2.357(6), Ru(1)-C(2) )
2.152(5), Ru(1)-Sn(1) ) 2.6587(5), C(1)-H(1) ) 0.89(4), C(1)-H(2) )
1.13(7); Sn(1)-Ru(1)-Pd(1) ) 143.462(19), C(21)-Ru(1)-Sn(1) )
173.33(13).
Figure 10. Energy level diagram of the Fenske-Hall molecular orbitals
of 17 with the corresponding orbital energies listed in electron volts (eV).
Figure 11. A contour diagram of the Fenske-Hall LUMO, 43A of 17.
To try to learn more about how the M(PBut3), M ) Pt, Pd,
groups have activated 10 and 11 toward this PhC2H insertion
reaction, we have investigated the reaction of 10 with Pt(PBut3)2
in the absence of PhC2H. When Pt(PBut3)2 was added to a
solution of 10 in CH2Cl2 at room temperature for 25 min, the
new compound PtOs(CO)4(SnPh3)(PBut3)(µ-H), 17, was formed
and subsequently isolated in 45% yield by TLC on silica gel.
Compound 17 was also characterized by a combination of IR,
1H NMR, and single-crystal X-ray diffraction analyses.
An ORTEP diagram of the molecular structure of 17 is shown
in Figure 9. The molecule can be viewed most simply as a Pt-
(PBut3) adduct of 10. The 12 electron Pt(PBut3) fragment has
formed bonding interactions with the osmium atom, the hydrido
ligand, and one of the CO ligands of 10. The Pt-Os distance,
Pt(1)-Os(1) ) 2.7628(3) Å, is significantly longer than that in
12 and 13. The shortness of the Pt-Os bonds in 12 and 13 can
be attributed to the presence of the bridging alkenyl ligands,
while the bridging hydrido ligand in 17 may produce a
lengthening effect on the Pt-Os bond in that complex.20 The
SnPh3 ligand on the Os atom is also positioned cis to the Pt
atom, Sn(1)-Os(1)-Pt(1) ) 84.652(12)°. The Os-Sn distance,
Os(1)-Sn(1) ) 2.7281(5) Å, is slightly longer than those found
in 12 and 13. The hydrido ligand was located and refined
Figure 9. ORTEP diagram of the molecular structure of 17 showing 40%
probability thermal ellipsoids. Selected bond distances (in Å) angles (deg)
are as follows: Pt(1)-Os(1) ) 2.7628(3), Pt(1)-P(1) ) 2.2808(14), Pt-
(1)-C(11) ) 1.982(6), Pt(1)-H(1) ) 1.92(6), Os(1)-C(11) ) 2.071(6),
Os(1)-Sn(1) ) 2.7281(5), Os(1)-H(1) ) 1.95(6); Sn(1)-Os(1)-Pt(1) )
84.652(12).
σ-bonded to the ruthenium atom and π-bonded to the palladium
atom. This changes its electron donation properties, and as a
result, the CO ligand that was terminal on the Pt atom in
compounds 12-15 occupies instead a position bridging the two
metal atoms in 16. The SnPh3 ligand on 16 is nearly trans to
the carbon atom C(21) of the bridging CO ligand, C(21)-Ru-
(1)-Sn(1) ) 173.33(13)° instead of being trans to the Pd atom,
Sn(1)-Ru(1)-Pd(1) ) 143.462(19)°. The Pd-Ru distance is
typical of Pd-Ru single bonds, Pd(1)-Ru(1) ) 2.7122(5) Å.
In fact, this is significantly shorter than the Ru-Pd distances
found in 1, 2.7877(12)-2.8398(11) Å.1a In the presence of a
Pd-Ru single bond, the Pd has a 16 electron configuration and
1
the Ru atom has 18 electrons. Its H NMR spectrum indicates
that 16 exists only as one isomer in solution. Both hydrogen
atoms on the alkenyl carbon atom C(1) were located and refined
in the structural analysis. They were also confirmed by 1H NMR
spectroscopy by the observation of their resonances at δ ) 5.53
and 4.42 ppm. The small coupling 2JH-H ) 2 Hz between them
is consistent with their gem-position.
(20) Teller, R. G.; Bau, R. Struct. Bonding 1981, 44, 1-82.
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A R T I C L E S
Adams et al.
Figure 12. Molecular orbitals responsible for the bonding interactions in 17 (31A, 35A, 40A, 42A).
Scheme 4
crystallographically, Pt(1)-H(1) ) 1.92(6) Å and Os(1)-H(1)
of molecular orbitals LUMO+2 to HOMO-13 are available,
see Supporting Information. There is a significant energy gap,
5.29 eV, between the HOMO and LUMO. The LUMO is largely
the antibonding equivalent of an interaction of the two metal
atoms with the π-bond of the bridging CO ligand, C(11)-O(11).
The bonding counterpart of this orbital is represented by the
HOMO-2, in which the d-orbital on the Pt atom has a slightly
different hybridization than that in the LUMO. The HOMO 42A
is largely “nonbonding” in character and is composed of atomic
d-orbitals localized largely on the two metal atoms. The Pt-
Os bond is shown clearly in Figure 12 in the HOMO-7 orbital.
Another important orbital is shown by the HOMO-11 31A
which shows the bond between the hydrido ligand and the two
metal atoms. This orbital is important because it shows how
the Pt atom activates the Os-H bond. The molecular orbitals
show clearly the types of interactions that we would expect for
10, but more importantly the LUMO reveals a feature of the
electronic structure that may provide additional insight into
the nature of the addition and insertion of the alkyne into the
Os-H bond. In particular, the LUMO contains a large com-
) 1.95(6) Å, and confirmed by its high field 1H NMR chemical
2
shift, δ ) -5.99 with its couplings to P, Pt, and Sn, JP-H
)
1
2
2
46 Hz, JPt-H ) 566 Hz, J119
) 46 Hz, J117
) 44 Hz.
Sn-H
Sn-H
The Os-H bond distance is much longer than that in 10, 1.67-
(4) Å.11 Most importantly, when 17 was treated with PhC2H,
it was converted to 12 in 28% yield. No additional quantities
of Pt(PBut3)2 are needed to promote the reaction. Thus, we
feel that 17 is most likely an intermediate in the formation
of 12.
To understand the electronic structure in 17 and its possible
role in the reaction of 17 with PhC2H, Fenske-Hall molecular
orbitals of 17 were calculated.15 For this calculation, the atomic
coordinates from the crystal structure were used, and the tert-
butyl groups on the PBut3 ligand and the phenyl groups on the
SnPh3 ligand were replaced with hydrogen, e.g., PH3 and SnH3.
An energy level diagram showing the frontier orbitals is shown
in Figure 10. The LUMO 43A (see Figure 11) and the HOMO
42A, HOMO-2 40A, HOMO-7 35A, and HOMO-11 31A
(see Figure 12) are key orbitals. Diagrams of the complete set
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7554 J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007

Metal Hydride Complex Activation by Pd-/Pt(PBut3)2 Groups
A R T I C L E S
ponent on the platinum atom. We believe that this empty orbital
serves as the landing site for the alkyne in its initial interactions
with 17.
Proposed Mechanism of Os-H Activation and Alkyne
Insertion. The reaction of 10 with PhC2H in the presence of
Pt(PBut3)2 begins with the formation of 17 by loss of one PBut3
ligand from Pt(PBut3)2. The empty orbital that is formed on the
Pt(PBut3) fragment then forms a bonding interaction with the
Os-H bond and one of the CO ligands of 10. The Os-H bond
is weakened with the formation of 17. The rest of the process
is shown in Scheme 4. The alkyne PhC2H then adds to the
LUMO of 17 at the platinum atom. Insertion of the alkyne ligand
into the Pt-H bond of the bridging hydrido ligand initiates C-H
bond formation. This may involve a four atom transition state.9
The hydrido ligand could be shifted to either of the alkyne
carbon atoms. This will produce an alkenyl ligand either HC2-
(H)Ph or PhC2H2 that subsequently adopts a conventional η2-
σ-π-bridging coordination mode. If the alkyne does indeed
interact with the platinum atom in the initial contact with 17,
then the bridging alkenyl ligand may initially adopt a bridging
mode with its π-bonding to the platinum atom, species A in
Scheme 4. The viability of the intermediate A is supported by
the observed structure of 16. For the osmium-platinum
compounds, a rearrangement follows the formation of A in
which the alkenyl ligand shifts its π-coordination to the osmium
atom and the bridging CO ligand then shifts to a terminal site
on the platinum atom to yield either 12 or 13 depending upon
which carbon atom of the acetylene received the hydrido ligand.
Shapley showed that bridging alkenyl ligands could readily
alternate their π-bonding between adjacent metal atoms.21
Similar mechanisms can explain the formation of 14 and 15
from the reactions of 11 with phenylacetylene and Pt(PBut3)2.
The platinum atoms in each of the compounds 12-15 and
17 and the palladium atom in 16 have 16 electron configurations
and could add yet another equivalent of PhC2H under the
appropriate conditions. In fact, we have found that such an
addition does occur to 12 under mild conditions.
Figure 13. An ORTEP diagram of the molecular structure of 18 showing
30% probability thermal ellipsoids. The methyl groups are not shown for
clarity. Selected bond distances (in Å) and angles (deg) are as follows:
Pt(1)-P(1) ) 2.3601(15), Pt(1)-Os(1) ) 2.7255(3), Pt(1)-C(20) ) 2.017-
(6), Os(1)-C(20) ) 2.253(6), Os(1)-C(21) ) 2.292(6), Os(1)-C(22) )
2.230(6), Os(1)-C(23) ) 2.369(6), Os(1)-Sn(1) ) 2.6540(4), C(20)-C(21)
) 1.416(8), C(21)-C(22) ) 1.446(8), C(22)-C(23) ) 1.396(8); Sn(1)-
Os(1)-Pt(1) ) 90.456(12).
shorter than C(21)-C(22) ) 1.446(8) Å and indicate that the
diene character of this ligand is still present when it is
coordinated. There is a Pt-Os bond, Pt(1)-Os(1) ) 2.7255(3)
Å, which is similar in length to those in 12 and 13. The SnPh3
ligand is positioned cis to the metal-metal bond, Sn(1)-Os-
(1)-Pt(1) ) 90.456(12)°, Os(1)-Sn(1) ) 2.6540(4) Å. The
osmium atom has only two terminal CO ligands.
The formation of 18 occurs by the addition of 1 equiv of
PhC2H to 12. As with the addition of PhC2H to 17, this may
also occur initially at the platinum atom which has only a 16
electron configuration in 12. C-C coupling to the alkenyl ligand
occurs, and a CO ligand is lost from the osmium atom when
the second double bond from the diphenylbutadienyl ligand
becomes bonded to the osmium atom; see Scheme 4. The
platinum atom in 18 has a 16 electron configuration, and the
osmium atom has 18 valence electrons. It is possible that 18
could add and couple yet another equivalent of PhC2H to its
butadienyl ligand, and a continuation of this process could lead
to a PhC2H polymer, but we have not investigated this yet.
When a solution of 12 and PhC2H in CH2Cl2 solvent was
heated to reflux for 60 min, the new compound PtOs(CO)3-
(SnPh3)(PBut3)[µ-HCC(Ph)C(H)C(H)Ph], 18, was obtained in
1
48% yield. Compound 18 was characterized by IR, H NMR,
and single-crystal X-ray diffraction analyses. An ORTEP
diagram of 18 is shown in Figure 13. Compound 18 contains a
bridging 2,4-diphenylbutadienyl ligand, HCC(Ph)C(H)C(H)Ph.
The four carbon atoms C(20), C(21), C(22), and C(23) are
π-bonded to the osmium atom, Os(1)-C(20) ) 2.253(6) Å, Os-
(1)-C(21) ) 2.292(6) Å, Os(1)-C(22) ) 2.230(6) Å, Os(1)-
C(23) ) 2.369(6) Å. C(20) is also σ-bonded to the platinum
atom, Pt(1)-C(20) ) 2.017(6) Å. The bonds C(20)-C(21) )
1.416(8) Å and C(22)-C(23) ) 1.396(8) Å are significantly
Conclusions
We have shown in this work that an unsaturated Pt(PBut3)
group generated from the compound Pt(PBut3)2 by loss of a
PBut3 ligand can be added to the hydride complexes 10 and 11,
by forming an interaction to the hydrido ligand, the metal atom,
and one of the CO ligands. It can facilitate insertion of the alkyne
PhC2H into the metal-hydrogen bond by providing a low lying
empty orbital through which the alkyne can become coordinated
and then be combined with the hydrido ligand. This is difficult
for the hydride complexes 10 and 11 to do by themselves
because both of these complexes have 18 electron configurations
and are electronically saturated. We have been able to make
both C-H and C-C bonds from 10 by using the Pt(PBut3)
activator.
(21) (a) Clauss, A. D.; Tachikawa, M.; Shapley, J. R.; Pierpont, C. G. Inorg.
Chem. 1981, 20, 1528-1533. (b) Shapley, J. R.; Richter, S. I.; Tachikawa,
M.; Keister, J. B. J. Organomet. Chem. 1975, 94, C43-C46.
(22) (a) Adams, R. D. J. Organomet. Chem. 2000, 600, 1-6. (b) Thomas, J.
M.; Johnson, B. F. G.; Raja, R.; Sankar, G.; Midgley, P. A. Acc. Chem.
Res. 2003, 36, 20-30. (c) Hermans, S.; Raja, R.; Thomas, J. M.; Johnson,
B. F. G.; Sankar, G.; Gleeson, D. Angew. Chem., Int. Ed. 2001, 40, 1211-
1215. (d) Guczi, L.; Schay, Z.; Stefler, G.; Mizukami, J. Molec. Catal.
1999, 141, 177-185. (e) Sinfelt, J. H. Bimetallic Catalysts. DiscoVeries,
Concepts and Applications; Wiley: New York, 1983. (f) Sinfelt, J. H. AdV.
Chem. Eng. 1964, 5, 37-74. (g) Sinfelt, J. H. Acc. Chem. Res. 1977, 10,
15-20. Oh, S. H.; Carpenter, J. E. J. Catal. 1986, 98, 178-190. (h)
Hogarth, M. P.; Ralph, T. R. Platinum Met. ReV. 2002, 46, 146-164. (i)
Hogarth, M. P.; Hards, G. A. Platinum Met. ReV. 1996, 40, 150-159.
Bimetallic cooperativity or synergism is an important feature
of many heterometallic catalysts.22 Such synergism may be
9
J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007 7555

A R T I C L E S
Adams et al.
expressed by a variety of mechanisms, but few are understood
in great detail. Here we have demonstrated a new example of
bimetallic synergism in unusual detail and clarity.
for assistance with the variable temperature NMR spectra.
Dedicated to the memory of F. Albert Cotton.
Supporting Information Available: CIF files for each of the
structural analyses. This material is available free of charge via
the Internet at http://pubs.acs.org.
Acknowledgment. This research was supported by the Office
of Basic Energy Sciences of the U.S. Department of Energy
under Grant No. DE-FG02-00ER14980. We thank STREM for
donation of a sample of Pt(PBut3)2 and Johnson Matthey for a
donation of K2PtCl4. We wish to thank Dr. Perry J. Pellechia
JA070617H
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7556 J. AM. CHEM. SOC. VOL. 129, NO. 24, 2007