Reactions of bis(tri- tert -butylphosphine)platinum with metal hydride complexes. the reactions of Pt(P-t-Bu3)2 with HRe(CO) 4SbPh3

Article abstract of DOI:10.1021/om100569j

Pt(P-t-Bu₃)₂ reacts with the rhenium hydride complex HRe(CO)₄(SbPh₃), 1, at 25 °C to give the complex PtRe(CO)₄(Ph)(P-t-Bu₃)(μ-SbPh₂)(μ-H), 2, in 75% yield by the oxidative-addition of a Sb-C bond on the SbPh₃ ligand of 1 to a Pt(P-t-Bu₃) group generated by loss of a P-t-Bu ₃ ligand from Pt(P-t-Bu₃)₂. Compound 2 contains a Pt-Re bond [Pt(1)-Re(1) = 3.0971(7) A] with a bridging SbPh₂ ligand and a bridging hydrido ligand. At 98 °C, Pt(P-t-Bu₃) ₂ reacts with two equivalents of 1 to yield the compounds PtRe ₂(CO)₈[PH(t-Bu₂)](Ph)(μ-SbPh ₂)₂(μ-H), 3, PtRe₂(CO)₈(SbPh ₃)(Ph)(μ-SbPh₂)₂(μ-H), 4, and PtRe ₂(P-t-Bu₃)(μ-SbPh₂)₂(μ-SbPh), 5. Compounds 3 and 4 both contain five-membered Re₂Sb₂Pt rings formed from two mutually bonded Re(CO)₄ groups and two bridging SbPh₂ ligands that are both bonded to the Pt atom. Compound 4 was obtained from 2 independently by reaction with 1. Pt(P-t-Bu₃) ₂ reacts with 1 at 68 °C under a hydrogen atmosphere to yield 2, 4, and the new compound, HPtRe₂(CO)₈(P-t-Bu ₃)(μ-SbPh₂)₂(μ-H), 6, which also contains a five-membered Re₂Sb₂Pt ring similar to those found in 3 and 4. Five compounds were obtained in low yields when 2 was thermally decomposed under nitrogen at 100 °C: 5 (4%); Re₂(CO) ₈(μ-SbPh₂)₂, 7 (6% yield); RePh(CO) ₄SbPh₃, 10 (4%); Re₂(CO)₈[PtH(CO)(P- t-Bu₃)](μ₃-SbPh)(μ-SbPh₂), 11 (4%); RePh(CO)₄[PtH(CO)P(t-Bu)₃](μ-SbPh₂), 12 (7%). Of these, only 12 is new. Compound 12 is a CO adduct of 2 and was obtained independently by the addition of CO to 2. The CO ligand was added to the platinum atom, the Pt-Re bond of 2 was cleaved, and the phenyl group was shifted to the rhenium atom. The two metal atoms are linked solely by the bridging SbPh₂ ligand. Seven compounds, 5 (9% yield), 7 (26%), Pt ₃(CO)₃(P-t-Bu₃)₃, 9 (71%), 11 (7%), 12 (8%), PtRe₂(CO)₉P(t-Bu)₃(μ-H) ₂, 13 (13%), and Re₃(CO)₁₃(μ₃- SbPh)(μ-SbPh₂), 14 (18%), were obtained when 2 was allowed to react with CO at room temperature. Of these, only compound 14 is new. Compound 14 contains no platinum atoms. The structure of 14 contains two Re(CO) ₄ groups linked by a bridging SbPh₂ ligand and a bridging SbPh ligand. The bridging SbPh ligand also contains a pendant Re(CO)₅ group.

Full text of DOI:10.1021/om100569j

Organometallics 2010, 29, 3887–3895 3887
DOI: 10.1021/om100569j
Reactions of Bis(tri-tert-butylphosphine)platinum with Metal Hydride
Complexes. The Reactions of Pt(P-t-Bu3)2 with HRe(CO)4SbPh3
Richard D. Adams* and William C. Pearl, Jr.
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
Received June 9, 2010
Pt(P-t-Bu3)2 reacts with the rhenium hydride complex HRe(CO)4(SbPh3), 1, at 25 °C to give the
complex PtRe(CO)4(Ph)(P-t-Bu3)(μ-SbPh2)(μ-H), 2, in 75% yield by the oxidative-addition of a
Sb-C bond on the SbPh3 ligand of 1 to a Pt(P-t-Bu3) group generated by loss of a P-t-Bu3 ligand from
˚
Pt(P-t-Bu3)2. Compound 2 contains a Pt-Re bond [Pt(1)-Re(1) = 3.0971(7) A] with a bridging
SbPh2 ligand and a bridging hydrido ligand. At 98 °C, Pt(P-t-Bu3)2 reacts with two equivalents of 1 to
yield the compounds PtRe2(CO)8[PH(t-Bu2)](Ph)(μ-SbPh2)2(μ-H), 3, PtRe2(CO)8(SbPh3)(Ph)(μ-
SbPh2)2(μ-H), 4, and PtRe2(P-t-Bu3)(μ-SbPh2)2(μ-SbPh), 5. Compounds 3 and 4 both contain
five-membered Re2Sb2Pt rings formed from two mutually bonded Re(CO)4 groups and two bridging
SbPh2 ligands that are both bonded to the Pt atom. Compound 4 was obtained from 2 independently
by reaction with 1. Pt(P-t-Bu3)2 reacts with 1 at 68 °C under a hydrogen atmosphere to yield 2, 4, and
the new compound, HPtRe2(CO)8(P-t-Bu3)(μ-SbPh2)2(μ-H), 6, which also contains a five-membered
Re2Sb2Pt ring similar to those found in 3 and 4. Five compounds were obtained in low yields when 2
was thermally decomposed under nitrogen at 100 °C: 5 (4%); Re2(CO)8(μ-SbPh2)2, 7 (6% yield);
RePh(CO)4SbPh3, 10 (4%); Re2(CO)8[PtH(CO)(P-t-Bu3)](μ3-SbPh)(μ-SbPh2), 11 (4%); RePh-
(CO)4[PtH(CO)P(t-Bu)3](μ-SbPh2), 12 (7%). Of these, only 12 is new. Compound 12 is a CO adduct
of 2 and was obtained independently by the addition of CO to 2. The CO ligand was added to the
platinum atom, the Pt-Re bond of 2 was cleaved, and the phenyl group was shifted to the rhenium
atom. The two metal atoms are linked solely by the bridging SbPh2 ligand. Seven compounds, 5 (9%
yield), 7 (26%), Pt3(CO)3(P-t-Bu3)3, 9 (71%), 11 (7%), 12 (8%), PtRe2(CO)9P(t-Bu)3(μ-H)2, 13
(13%), and Re3(CO)13(μ3-SbPh)(μ-SbPh2), 14 (18%), were obtained when 2 was allowed to react
with CO at room temperature. Of these, only compound 14 is new. Compound 14 contains no
platinum atoms. The structure of 14 contains two Re(CO)4 groups linked by a bridging SbPh2 ligand
and a bridging SbPh ligand. The bridging SbPh ligand also contains a pendant Re(CO)5 group.
Introduction
phosphine ligands and then adding the M(P-t-Bu3) group so
formed to one or more of the metal-metal bonds of the
cluster complex, e.g., eqs 1 and 2.4,5
Mixed-metal cluster complexes have been of interest for
their ability to facilitate transformations of hydrocarbyl
ligands at bimetallic centers.1 Bimetallic cluster complexes
are of interest for applications in homogeneous catalysis2
and as precursors to heterogeneous catalysts.3 Understand-
ing the reactivity of the heteronuclear metal-metal bond is
central to the development of these complexes as catalysts.
In previous studies, we have shown that the bis(tri-tert-
butyl)phosphine complexes M(P-t-Bu3)2, M = Pd or Pt,
react with polynuclear metal carbonyl cluster complexes
containing metal-metal bonds by dissociating one of their
*To whom correspondence should be addressed. E-mail: adams@
mail.chem.sc.edu.
(1) Ritleng, V.; Chetcuti, M. J. Chem. Rev. 2007, 107, 797–858.
(2) (a) Hogarth, G.; Kabir, S. E.; Nordlander, E. Dalton Trans. 2010,
39, 6153–6174. (b) Adams, R. D.; Captain, B. J. Organomet. Chem. 2004,
689, 4521–4529.
(3) (a) Thomas, J. M.; Johnson, B. F. G.; Raja, R.; Sankar, G.;
Midgley, P. A. Acc. Chem. Res. 2003, 36, 20–30. (b) Alexeev, O.; Gates,
B. C. Ind. Eng. Chem. Res. 2003, 42, 1571–1587. (c) Braunstein, P.; Rose, J.
In Metal Clusters in Catalysis; Braunstein, P.; Oro, L. A.; Raithby, P. R.,
Eds.; Wiley-VCH: Weinheim, 1999; Vol. 2, pp 616-665.
(4) (a) Adams, R. D.; Captain, B. Acc. Chem. Res. 2009, 42, 409–418.
(b) 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. (c) Adams, R. D.;
Boswell, E. M.; Captain, B.; Zhu, L. J. Cluster Sci. 2008, 19, 121–132.
(5) (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.; Trufan, E. J. Organomet. Chem. 2008,
693, 3593–3602. (c) Adams, R. D.; Captain, B.; Hall, M. B.; Trufan, E.; Yang,
X. J. Am. Chem. Soc. 2007, 129, 12328–12340.
r
2010 American Chemical Society
Published on Web 08/18/2010
pubs.acs.org/Organometallics

3888 Organometallics, Vol. 29, No. 17, 2010
Adams and Pearl
161.9 MHz, respectively. 31P{1H} NMR spectra were externally
referenced against 85% ortho-H3PO4. Mass spectrometric (MS)
measurements performed by a direct-exposure probe using
electron impact ionization (EI) were made on a VG 70S instru-
ment. Pt(P-t-Bu3)2 and SbPh3 were obtained from Strem and
were used without further purification. Product separations
were performed by TLC in air on Analtech 0.25 and 0.5 mm
˚
silica gel 60 A F254 glass plates.
An Improved Synthesis of HRe(CO)4SbPh3, 1. A 65.0 mg
amount of Re2(CO)10 was dissolved in 40 mL of benzene. The
flask was partially submerged in an ice bath, and the solution
was irradiated (UV-vis) by using a high-pressure mercury UV
lamp (American Ultraviolet Company, 1000 W) at the 250 wpi
setting while purging with H2 at 1 atm for 30 min. A 140 mg
sample of SbPh3 was then added to the solutions, and the
irradiation was continued for another 15 min. The solvent was
removed in vacuo, and the products were then isolated by TLC
by using a 5:1 hexane/methylene chloride solvent mixture to
yield in order of elution the following: a colorless band of HRe-
(CO)4SbPh3,8 1, 79.2 mg (61%), and a colorless band of HRe-
(CO)3(SbPh3)2, 16.9 mg (9%). Spectra for HRe(CO)3(SbPh3)2:
IR νCO (cm-1 in hexane): 2016(vs), 1938(m), 1929(m). 1H NMR
(CD2Cl2, in ppm): δ 7.4-7.1 (m, 30H, Ph), -5.7 (s, 1H, hydride).
Anal. Calcd: 47.93, C; 3.20, H. Found: 47.63, C; 3.19, H.
Synthesis of PtRe(CO)4(Ph)(P-t-Bu3](μ-SbPh2)(μ-H), 2. A
29.8 mg (0.0497 mmol) amount of Pt(P-t-Bu3)2 was added to a
solution of 22.5 mg (0.0345 mmol) of 1 dissolved in 25 mL of
hexane, and the mixture was allowed to stir at room temperature
for 1 h. The solvent was removed in vacuo, and the product was
then isolated by TLC using a 3:1 hexane/methylene chloride
elution solvent mixture to yield a yellow band of PtRe(CO)4-
(Ph)(P-t-Bu3)(μ-SbPh2)(μ-H), 2, 26.7 mg (75% yield). Spectral
data for 2: IR (νCO in hexane, cm-1): 2081(m), 1987(vs), 1953(s).
1H NMR (400 MHz, CD2Cl2, 25 °C, TMS): δ 6.8-7.5 (m, Ph,
15H), 1.5 (d, But, 27H, 2JP-H = 12 Hz), -13.5 (d, hydride, 1H,
2JP-H = 11 Hz, 1J195Pt-H = 429.1 Hz). 31P NMR: δ 68.3 (s, P,
1JPt-P = 3411 Hz) ppm. Anal. Calcd: C 38.89, H 4.13. Found: C
39.11, H 4.26.
Figure 1. ORTEP diagram of the molecular structure of PtOs-
(CO)4SnPh3(P-t-Bu3)((μ-H).7
The addition of a bridging Pt(P-t-Bu3) group to a poly-
nuclear metal carbonyl complex can change the reactivity of
that complex. For example, it has been shown that the Pt(P-t-
Bu3) group facilitates CO ligand substitution reactions in
Os3(CO)12.6 It was also shown that the Pt(P-t-Bu3) group can
activate metal-hydrogen bonds. For example, the addition
of Pt(P-t-Bu3)2 to solutions of the compounds HM(CO)4-
SnPh3, M = Ru or Os, greatly enhanced their reactivity
toward insertion of the alkyne HC2Ph into the M-H bond.
It was shown that the activation of the M-H bond occurs
through an association of a Pt(P-t-Bu3) group to the M-H.
Details of this association were revealed by an X-ray crystallo-
graphic characterization of the compound PtOs(CO)4Sn-
Ph3(P-t-Bu3)(μ-H), a Pt(P-t-Bu3) adduct of HOs(CO)4(SnPh3).7
The terminal hydride ligand of the HOs(CO)4(SnPh3) was
converted into a bridging hydride ligand in the Pt(P-t-Bu3)
adduct, PtOs(CO)4SnPh3(P-t-Bu3)((μ-H), and a Pt-Os bond
was formed; see Figure 1.
We have now investigated the reaction of Pt(P-t-Bu3)2 with
the rhenium hydride complex HRe(CO)4(SbPh3), 1, which is
isoelectronic and isostructural to HOs(CO)4(SnPh3). Com-
pound 1 also forms a Pt(P-t-Bu3) addition product, but this
reaction is more complex than that involving the HOs(CO)4-
(SnPh3) complex. In fact, the addition of Pt(P-t-Bu3) to 1 is
accompanied by a chemical transformation involving oxida-
tive addition of an Sb-C bond on the SbPh3 ligand of 1 to a
Pt(P-t-Bu3) group generated by loss of a P-t-Bu3 ligand from
Pt(P-t-Bu3)2 to yield the complex PtRe(CO)4(Ph)(P-t-Bu3)-
(μ-SbPh2)(μ-H), 2. The results of our studies of the reaction
of Pt(P-t-Bu3)2 with complex 1 are reported herein.
Reaction of Pt(P-t-Bu3)2 with 1 at 98 °C. A 23 mg (0.0384
mmol) portion of Pt(PBut3)2 was added to a solution of 23.2 mg
(0.356 mmol) of ReH(CO)4SbPh3 dissolved in 25 mL of heptane,
and the mixture was heated to reflux for 2 h. The solvent was
removed in vacuo, and the products were then isolated by TLC
using a 4:1 hexane/methylene chloride solvent mixture to yield
the following in order of elution: a yellow band of 2, 1.2 mg (3%
by Re), a colorless band of Re2(CO)8(μ-SbPh2)2,9 1.8 mg (9%
yield), a yellow band of PtRe2(CO)8[PH(t-Bu2)](Ph)(μ-SbPh2)2-
(μ-H), 3, 2.8 mg (10%), an orange band of PtRe2(CO)8(SbPh3)-
(Ph)(μ-SbPh2)2(μ-H), 4, 1.5 mg (5% yield), and an orange band
of the known compound PtRe2(P-t-Bu3)(μ-SbPh2)2(μ-SbPh), 5,7
2.1 mg (7% yield). Spectral data for 3: IR (νCO in hexane,
cm-1): 2094(s), 2073(m), 2006(vs), 1999(s), 1988(s), 1980(m),
1
1968(w), 1957(s) cm-1. H NMR (400 MHz, CD2Cl2, 25 °C,
TMS): δ 6.4-7.5 (m, Ph, 25H), 4.5 (d, P-H, 1H, 1JP-H = 356
Hz, 2J195Pt-H = 18 Hz), 0.9 (d, t-Bu, 18H, 2JP-H = 15 Hz), -13.0
(d, 1H, 3J195Pt-H = 40 Hz, 4JP-H = 4 Hz). 31P NMR: δ 36.8 (d, P,
1
1JPt-P = 3059 Hz, JH-P = 387 Hz). MS EI/MS: m/z
1568 (Mþ), 1540 (Mþ - CO), 1490 (Mþ - CO, - C6H6). The
isotope distribution pattern is consistent with the presence of two
rhenium, one platinum, and two antimony atoms. Spectral data
for 4: IR (νCO in hexane, cm-1): 2094(s), 2073(w), 2006(vs),
1999(s), 1989(s), 1979(m),1968(w), 1956(m) cm-1. 1H NMR (400
MHz, CD2Cl2, 25 °C, TMS): δ 6.8-7.5 (m, Ph, 40H), -12.8 (s,
Experimental Section
General Data. Reagent grade solvents were dried by the stan-
dard procedures and were freshly distilled prior to use. Infrared
spectra were recorded on a Thermo Nicolet Avatar 360 FT-IR
spectrophotometer. 1H NMR and 31P{1H} NMR were recorded
on a Varian Mercury 400 spectrometer operating at 400.1 and
1
1H, JPt-H = 53 Hz) ppm. MS EI/MS: m/z 1774 (M+), 1718
(Mþ - 2CO), 1696 (Mþ - C6H6). The isotope distribution
(6) Adams, R. D.; Captain, B.; Smith, M. D.; Zhu, L. Inorg. Chem.
2006, 45, 430–436.
(7) (a) Adams, R. D.; Captain, B.; Trufan, E.; Zhu, L. J. Am. Chem.
Soc. 2007, 129, 7545–7556. (b) Adams, R. D.; Captain, B.; Zhu, L. J. Am.
Chem. Soc. 2006, 128, 13672–13673.
(8) Adams, R. D.; Captain, B.; Pearl, W. C., Jr. J. Organomet. Chem.
2008, 693, 1636–1644.
(9) Raja, R.; Adams, R. D.; Blom, D. A.; Pearl, W. C., Jr.; Gianotti,
E.; Thomas, J. M. Langmuir 2009, 25, 7200–7204.

Article
Organometallics, Vol. 29, No. 17, 2010 3889
pattern is consistent with the presence of two rhenium, one
platinum, and three antimony atoms.
of Re2(CO)8(μ-SbPh2)2, 7, 2.0 mg (26%), a yellow band of
Re3(CO)13(μ3-SbPh)(μ-SbPh2), 14, 1.1 mg (18%), a colorless
band of 11, 0.7mg(7%), anorangebandof5, 1.1 mg (9%), a yellow
band of 12, 1.1 mg (8%), and a yellow band of 9, 4.0 mg (71%).
Spectral data for 14: IR (νCO in hexane, cm-1): 2126(m), 2077(vw),
2062(vs), 2034(vs), 2030(s), 2025(s), 2006(s), 1996(m), 1991(m),
Reaction of Pt(P-t-Bu3)2 with 1 under an Atmosphere of Hydro-
gen at 68 °C. A 16.9 mg amount of Pt(P-t-Bu3)2 was added to a
solution of 31.7 mg of HRe(CO)4(SbPh3) dissolved in 25 mL of
hexane, and the mixture was allowed to reflux for 3 h while
purging with H2. The solvent was removed in vacuo, and the
products were then isolated by TLC by using a 4:1 hexane/
methylene chloride solvent mixture to yield the following in
order of elution: a yellow band of 2, 7.2 mg (14% yield), an
orange band of HPtRe2(CO)8(P-t-Bu3)(μ-SbPh2)2(μ-H), 6, 8.0 mg
(21% yield), and a yellow band of 4, 2.2 mg (5% yield). Spectral
data for 6: IR (νCO in hexane, cm-1): 2094(m), 1971(w), 2005(vs),
1998(s), 1987(m), 1977(w), 1965(vw), 1954(m) cm-1. 1H NMR
(400 MHz, CD2Cl2, 25 °C, TMS): δ 7.0-7.7 (m, Ph, 15H), 1.3 (d,
1
1984(vs), 1974(s), 1952(s). H NMR (400 MHz, COC2D6, rt,
TMS): δ 7.2-7.7 (m, Ph, 15H) ppm. MS EI/MS: 1398 (Mþ),
1370 (-CO), 1342 (Mþ - 2CO), 1314 (Mþ - 3CO), 1286 (Mþ -
4CO), 1258 (Mþ - 4CO), 1230 (Mþ - 4CO) m/z. The isotope
distribution pattern is consistent with the presence of one anti-
mony and three rhenium atoms.
Conversion of 4 to 3. A 6.0 μL (0.0324 mmol) portion of PH(t-
Bu)2 was added to 63.2 mg (0.356 mmol) of 4 dissolved in 30 mL
of hexane, and the mixture was allowed to stir at 25 °C for 15
min. The solvent was then removed in vacuo, and the products
were separated by TLC using a 4:1 hexane/methylene chloride
solvent mixture to yield in order of elution a colorless band of
SbPh3, 6.9 mg (55%), and a colorless band of 3, 36.4 mg (65%).
Crystallographic Analyses: 2, 3, 4, 6, 12, and 14. Crystals of
yellow 2, suitable for X-ray diffraction, were obtained by slow
evaporation of solvent from a solution in hexane solvent at
room temperature. Crystals of yellow 3, yellow 4, yellow 6,
yellow 14, and brown 12 suitable for X-ray diffraction were
obtained by slow evaporation of solvent from solutions in
methylene chloride/hexane solvent mixtures at -25 °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 by using Mo KR radiation (λ =
t-Bu, 27H, 2JP-H = 12 Hz), -9.9 (d, hydride, 1H, 1J
=
=
195Pt-H
912 Hz, 2JP-H =13Hz), -13.0 (d, 1H, 3J195Pt-H =28 Hz, 4JP-H
10 Hz). 31P NMR: δ 102.1 (s, P, 1J195Pt-P = 3401 Hz). MS EI/
MS: 1548 (Mþ), 1518 (Mþ - H2, -CO), 1491 (Mþ - H, -2CO),
1470 (Mþ - C6H6) m/z. The isotope distribution pattern is
consistent with the presence of two rhenium, one platinum, and
two antimony atoms.
Addition of 1 to 2. 1 (34.8 mg, 0.0534 mmol) was added to 43.3
mg (0.0413 mmol) of 2 dissolved in 50 mL of hexane, and the
mixture was heated to reflux for 1.5 h. The solvent was removed
in vacuo, and the products were separated by TLC using a 4:1
hexane/methylene chloride solvent mixture to give in order of
elution a yellow band of 2, 13.0 mg (30% recovered), a colorless
band of 1, 4.6 mg (13%), a colorless band of Re2(μ-SbPh2)2-
(CO)8,9 7, 2.1 mg (9% yield), a yellow band of Re2(μ-H)(μ-
SbPh2)SbPh3(CO)7,8 8, 2.9 mg (12% yield), an orange band of 4,
12.8 mg (18% based on 2), and Pt3(CO)3(P-t-Bu3)3,11 9,
2.8 mg (5% yield).
˚
0.71073 A). The raw data frames were integrated with the SAINTþ
program by using a narrow-frame integration algorithm.13
Correction for Lorentz and polarization effects were also ap-
plied with SAINTþ. An empirical absorption correction based
on the multiple measurement of equivalent reflections was
applied using the program SADABS. All structures were solved
by a combination of direct methods and difference Fourier
syntheses and refined by full-matrix least-squares on F2, using
the SHELXTL software package.14 All non-hydrogen atoms
were refined with anisotropic thermal parameters. Unless in-
dicated otherwise, the hydrogen atoms were placed in geome-
trically idealized positions and included as standard riding
atoms during the least-squares refinements. Crystal data, data
collection parameters, and results of the refinements are listed in
Table 1. Compounds 2, 3, 4, and 6 all crystallized in the
monoclinic crystal system. The space group P21/n was con-
firmed for 3 and 14 on the basis of the systematic absences
observed in the data. The alternative standard setting of the
space group P21/n, P21/c, was selected for 2 and 4 on the basis of
the systematic absences observed in the data for both of these
compounds. The space group C2/c was confirmed for 7 on the
basis of the systematic absences observed in the data. With Z = 16
there are two independent molecules in the asymmetric unit.
The hydrido ligands in 2 and 4 were located and refined in the
structural analyses using isotropic thermal parameters. The
hydrido ligand in 3 was located in difference Fourier maps.
The hydrido ligand in 3 was refined by using the constraint
Thermal Decomposition of 2 at 100 °C. A 16.2 mg sample of 2
was dissolved in toluene-d8 and placed in a sealed NMR tube
under nitrogen. The tube was heated in an oil bath for 1 h. The
formation of benzene was confirmed in the 1H NMR spectrum
of the solution. The products were then separated by TLC to
yield in order of elution a colorless band of the known com-
pound Re2(CO)8(μ-SbPh2)2, 7,9 0.5 mg (6%), a colorless band of
the known compound RePh(CO)4SbPh3, 10,8 0.5 mg (4%), a
colorless band of the known compound Re2(CO)8[PtH(CO)(P-
t-Bu3)](μ3-SbPh)(μ-SbPh2), 11,10 0.5 mg (4%), an orange band
of the known compound PtRe2(P-t-Bu3)(μ-SbPh2)2(μ-SbPh),
5,10 0.5 mg (4%), and a brown band of RePh(CO)4[PtH(CO)P-
(t-Bu)3](μ-SbPh2), 12, 1.2 mg (7%). Spectral data for 12: IR (νCO
in hexane, cm-1): 2072(m), 2034(br), 1981(s), 1966(vs), 1938(m).
1H NMR (400 MHz, C6D6, rt, TMS): δ 7.0-8.3 (m, Ph, 15H), 1.0
(d, t-Bu, 27H, 2JP-H = 13 Hz), -3.8 (d, hydride, 1H, 1J
=
195Pt-H
750 Hz, 2JP-H = 14 Hz). 31P NMR: δ 94.8 ppm (1J195Pt-P = 2534
Hz). MS EI/MS: 1148 (Re2(CO)8(SbPh2)2), 1148 (Re2(CO)8-
(SbPh2)2 -CO), 1076 (Mþ - H), 972 (Mþ - Ph, -CO) m/z. The
isotope distribution pattern is consistent with the presence of
one rhenium, one platinum, and one antimony atoms.
Reaction 2 with CO. Under nitrogen, 14.0 mg of 2 was
dissolved in benzene-d6 in an NMR tube. Then 300 μL of CO
was added to the tube via syringe. The tube was shaken and then
allowed to sit at room temperature for 12 h. A 1H NMR
spectrum after this time showed that all of the signals for 2
had disappeared. The solution was transferred to a flask. The
solvent was removed in vacuo, and the products were separated
by TLC using 4:1 hexane/methylene chloride solvent mixture to
yield in order of elution a yellow band of the known compound
PtRe2(CO)9P(t-Bu)3(μ-H)2,12 13, 0.9 mg (13%), a colorless band
˚
M-H equals 1.75 A. Compounds 6 and 12 crystallized in the
triclinic crystal system. The space group P1 was assumed and
confirmed by the successful solution and refinement of the
structure. Both hydrido ligands in 6 were located in a difference
Fourier map, but H1 was refined by using a bond length
˚
constraint M-H equals 1.75 A. The hydrido ligand in 12 was
located and refined in the structural analyses using an isotropic
thermal parameter.
(10) Adams, R. D.; Pearl, W. C., Jr. Inorg. Chem. 2010, 49,
6188-6195.
(11) Goel, R. G.; Ogini, W. O.; Srivastava, R. C. J. Organomet. Chem.
1981, 214, 405–417.
(12) Adams, R. D.; Captain, B.; Smith, M. D.; Beddie, C.; Hall, M. B.
(13) SAINTþ Version 6.2a; Bruker Analytical X-ray Systems, Inc.:
Madison, WI, 2001.
(14) Sheldrick, G. M. SHELXTL Version 6.1; Bruker Analytical X-ray
Systems, Inc.: Madison, WI, 1997.
J. Am. Chem. Soc. 2007, 129, 5981–5991.

3890 Organometallics, Vol. 29, No. 17, 2010
Adams and Pearl
Table 1. Crystallographic Data for Compounds 2, 3, 4, 6, 12, and
14
2
3
4
empirical formula
ReSbPtPO4- Re2Sb2PtPO8- Re2Sb3PtO8-
C34H43 C46H45 C56H41
1049.69 1567.78 1774.63
fw
cryst syst
lattice params
monoclinic
monoclinic
monoclinic
˚
a (A)
10.247(2)
12.017(3)
30.009(10)
90.00
12.0949(4)
33.6607(12)
13.1677(4)
90.00
13.6009(8)
10.0159(6)
40.894(2)
90.00
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
97.681(14)
90.00
110.179(1)
90.00
96.358(1)
90.00
3
˚
V (A )
3662.1(18)
P21/c
4
5031.8(3)
P21/n
4
5536.5(6)
P21/c
4
space group
Z value
F
calc (g/cm3)
1.904
7.916
294(2)
56.68
7892
2.070
8.702
296(2)
56.64
9918
2.129
8.365
294(2)
56.68
10 838
μ(Mo KR) (mm-1
temperature (K)
2θmax (deg)
)
no. obsd reflns
(I > 2σ(I))
no. params
384
555
635
goodness of fit
max. shift in cycle
1.029
0.002
0.0298; 0.0777 0.0367; 0.0736 0.0434; 0.0859
1.078
0.002
1.069
0.001
residualsa: R1; wR2
absorp corr
max./min.
1.000/0.360
2.021
3
1.000/0.545
1.000/0.142
largest peak in
final diff map (e /A )
1.561
1.394
-
˚
Figure 2. ORTEP diagram of the molecular structure of PtRe-
(CO)4(Ph)(P-t-Bu3)(μ-SbPh2)(μ-H), 2, showing 30% probabil-
ity thermal ellipsoids. The hydrogen atoms on the ligands are
6
12
14
empirical formula
Re2Sb2PtPO8- ReSbPtPO5- Re3Sb2O13
C44H49 C35H43 C31H15
1547.79 1077.70 1397.53
-
˚
omitted for clarity. Selected bond distances (A) and angles (deg)
are as follows: Pt(1)-Re(1) = 3.0971(7), Pt(1)-C(27) = 2.051(5),
Pt(1)-P(1) = 2.3692(13), Pt(1)-Sb(1) = 2.5180(7), Re(1)-
Sb(1) = 2.6769(6), Pt(1)-H(1) = 1.65(5), Re(1)-H(1) = 1.84(5);
Sb(1)-Re(1)-Pt(1) = 51.078(15), Pt(1)-Sb(1)-Re(1) =
73.120(17), Sb(1)-Pt(1)-Re(1) = 55.802(15), P(1)-Pt(1)-
Sb(1) = 171.29(3).
fw
cryst syst
lattice params
triclinic
triclinic
monoclinic
˚
a (A)
11.4655(4)
12.7853(4)
17.9052(6)
74.631(1)
72.235(1)
86.530(1)
11.3669(5)
12.0842(6)
14.5035(7)
80.269(1)
85.115(1)
70.918(1)
12.698(2)
17.635(3)
16.896(3)
90.00
101.845(4)
90.00
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
two metal atoms: one of platinum and one of rhenium. The
two metal atoms are mutually bonded and are bridged by a
SbPh2 ligand and one bridging hydrido ligand. The Pt-Re
3
˚
V (A )
2409.59(14)
P1
1854.69(15)
P1
3702.9(10)
P21/n
4
2.507
11.270
294(2)
52.74
5313
space group
Z value
2
2
˚
F
calc (g/cm3)
2.133
9.084
294(2)
56.62
8953
1.930
7.820
294(2)
56.62
8100
bond distance [Pt(1)-Re(1) = 3.0971(7) A] is significantly
μ(Mo KR) (mm-1
temperature (K)
2θmax (deg)
)
longer than the Pt-Re bond distance of 2.9265(3) A found in
˚
the complex PtRe2(CO)9(P-t-Bu3)(μ -SbPh2)(μ-H), 16, which
was obtained from the reaction of Pt(P-t-Bu3)2 with Re2-
(CO)8(μ-SbPh2)(μ-H).15 The longer length of the Pt-Re
bond in 2 is probably due to the presence of the bridging
hydride ligand.16 The hydrido ligand was located and refined
no. obsd reflns
(I > 2σ(I))
no. params
540
1.004
0.001
410
1.039
0.002
442
goodness of fit
max. shift in cycle
1.022
0.001
0.0392; 0.0820 0.0227; 0.0552 0.0455; 0.1123
˚
in the structure analysis: Pt(1)-H(1) = 1.65(5) A and Re-
residualsa: R1; wR2
˚
(1)-H(1) = 1.84(5) A. As expected, it exhibits the usual
absorp corr, max./min. 1.000/0.619
largest peak in 1.750
1.000/0.677
1.004
1.000/0.214
3.025
1
high-field resonance shift in the H NMR spectrum, δ =
-
3
final diff map (e /A )
˚
-13.5, with suitable couplings to the phosphorus and plati-
P
P
P
2
num atoms: JP-H = 11 Hz and 1J
= 429.1 Hz.
a R1
=
hkl(||Fobs| - |Fcalc||)/ hkl|Fobs|; wR2 = [ hklw(|Fobs| - |
195Pt-H
P
P
F
F
calc|)2/ hklwFobs
]
2 1/2. w = 1/σ2(Fobs); GOF = [ hklw(|Fobs| - |
Compound 2 contains a phenyl group σ-bonded to the
calc|)2/(ndata - nvari)]1/2
.
˚
platinum atom; Pt(1)-C(27) = 2.051(5) A. There is also a
bridging SbPh2 ligand. The Pt-Sb and Re-Sb bond dista-
Results
˚
˚
nces [Pt(1)-Sb(1) = 2.5180(7) A, Re(1)-Sb(1) = 2.6769(6) A]
are similar to the Pt-Sb and Re-Sb bond distances found in 16:
The compound PtRe(CO)4(Ph)(P-t-Bu3)(μ-SbPh2)(μ-H), 2,
was obtained in 75% yield from the reaction of Pt(P-t-Bu3)2
with 1 in a hexane solution at room temperature in 1 h.
˚
˚
Pt(1)-Sb(1) = 2.5160(4) A and Re(2)-Sb(1) = 2.6863(5) A.
There are four linear terminal carbonyl ligands on the rhenium
1
Compound 2 was characterized by IR and H NMR spec-
(15) Adams, R. D.; Hall, M. B.; Pearl, W. C., Jr.; Yang, X. Inorg.
Chem. 2009, 48, 652–662.
(16) (a) Bau, R.; Drabnis, M. H. Inorg. Chim. Acta 1997, 259, 27–50.
(b) Teller, R. G.; Bau, R. Struct. Bonding (Berlin) 1981, 41, 1–82.
troscopy and by elemental and single-crystal X-ray diffrac-
tion analyses. An ORTEP diagram of the molecular
structure of 2 is shown in Figure 2. The compound contains

Article
Organometallics, Vol. 29, No. 17, 2010 3891
Scheme 1
Figure 4. ORTEP diagram of the molecular structure of PtRe2-
(CO)8(SbPh3)(Ph)(μ-SbPh2)2(μ-H), 4, showing 30% probability
thermal ellipsoids. The hydrogen atoms on the ligands are omi-
Figure 3. ORTEP diagram of the molecular structure of PtRe2-
(CO)8[PH(t-Bu)2](Ph)(μ-SbPh2)2(μ-H), 3, showing 30% prob-
ability thermal ellipsoids. The hydrogen atoms on the ligands
˚
tted for clarity. Selected interatomic bond distances (in A) are as
follows: Pt(1)-Sb(1) = 2.5744(5), Pt(1)-Sb(2) = 2.6353(5),
Pt(1)-Sb(3) = 2.5612(5), Re(1)-Re(2) = 3.2761(4), Re(1)-
Sb(1) = 2.7675(5), Re(2)-Sb(2) = 2.7879(5), Re(1)-H(1) =
1.69(6), Re(2)-H(1) = 1.85(6), Pt(1)-C(1) = 2.059(7); Sb(1)-
Pt(1)-Sb(2) = 92.570(15), Pt(1)-Sb(1)-Re(1) = 116.679(19),
Pt(1)-Sb(2)-Re(2) = 123.166(17), Sb(1)-Re(1)-Re(2) =
92.135(12), Sb(2)-Re(2)-Re(1) = 93.201(13).
˚
are omitted for clarity. Selected interatomic bond distances (A)
and angles (deg) are as follows: Pt(1)-C(49) = 2.068(6), Pt(1)-
P(1) = 2.3011(16), Pt(1)-Sb(1) = 2.6029(4), Pt(1)-Sb(2) =
2.6270(4), Re(1)-Sb(1) = 2.7855(4), Re(1)-Re(2) = 3.2863(4),
Re(1)-H(1) = 1.748(10), Re(2)-Sb(2) = 2.7829(4), Re(2)-
H(1) = 1.753(10); Sb(1)-Pt(1)-Sb(2) = 91.868(13), Sb(1)-
Re(1)-Re(2) = 93.759(11), Sb(2)-Re(2)-Re(1) = 90.566(11),
Pt(1)-Sb(1)-Re(1) = 125.606(16), Pt(1)-Sb(2)-Re(2) =
122.492(15).
structure of 3 and 4 are shown in Figures 3 and 4, respe-
ctively. Both compounds consist of a heterocyclic five-mem-
bered ring containing two rhenium atoms and a platinum
atom that is linked to the rhenium atoms by two bridging
SbPh2 ligands. The platinum atom is bonded to both SbPh2
atom and a tri-tert-butylphosphine ligand on the platinum
˚
atom: Pt(1)-P(1) = 2.3692(13) A. The SbPh2 ligand is form-
˚
ligands: Pt(1)-Sb(1) = 2.6029(4) A and Pt(1)-Sb(2) =
ally a three-electron donor to the two metal atoms. Formally,
the platinum atom in 2 is in a þ2 oxidation state and has a
16-electron configuration, and the rhenium atom is in a þ1
oxidation state and has an 18-electron configuration.
˚
˚
2.6270(4) A in 3 and Pt(1)-Sb(1) = 2.5744(5) A and Pt(1)-
Sb(2) = 2.6353(5) A in 4. These distances are slightly longer
˚
than the Pt-Sb distance in the three-membered ring in 2:
˚
˚
2.5180(7) A. TheRe-Sbdistances[Re(1)-Sb(1) = 2.7855(4) A,
˚
Re(2)-Sb(2) = 2.7829(4) A in 3 and Re(1)-Sb(1) =
2.7675(5) A, Re(2)-Sb(2) = 2.7879(5) A in 4] are also
slightly longer than those in 2, 2.6769(6) A. Both compounds
˚
˚
˚
were obviously formed by the reaction of Pt(P-t-Bu3)2 with
two equivalents of 1. It seems likely that compound 2 was an
intermediate in this reaction, and this is supported by our
study of the reaction of 1 with 2; see below. The two rhenium
atoms in 3 and 4 are mutually bonded: Re(1)-Re(2) =
When the reaction of 1 with Pt(P-t-Bu3)2 was performed in
a heptane solution at reflux (98 °C), compound 2 was not
obtained, but three other compounds were formed: PtRe2-
(CO)8[PH(t-Bu2)](Ph)(μ-SbPh2)2(μ-H), 3 (10% yield), PtRe2-
(CO)8(SbPh3)(Ph)(μ-SbPh2)2(μ-H), 4 (5% yield), and PtRe2-
(P-t-Bu3)(μ-SbPh2)2(μ-SbPh), 510 (7% yield). See Scheme 1.
Compounds 3 and 4 are new and were characterized by IR
˚
˚
3.2863(4) A in 3 and Re(1)-Re(2) = 3.2761(4) A in 4. These
Re-Re distances are considerably longer than the Re-Re
distance in Re2(CO)10, 3.042(1) A.17 The increase in the Re-
˚
Re bond length is probably due to the presence of a bridging
hydrido ligand across the Re-Re bond in both compounds.13
1
and H NMR spectroscopy and by mass spectrometry and
single-crystal X-ray diffraction analyses. Compound 5 was
obtained by us previously from the reaction of Re2(CO)8(μ-
SbPh2)2 with Pt(P-t-Bu3)2.10 ORTEP diagrams of the molecular
(17) Churchill, M. R.; Amoh, K. N.; Wasserman, H. J. Inorg. Chem.
1981, 20, 1609–1611.

3892 Organometallics, Vol. 29, No. 17, 2010
Adams and Pearl
The Re-Re distances are only slightly longer than the Re-Re
distances between the rhenium atoms of the hydride-bridged
Re-Re bonds in Re3(CO)12(μ-H)3 of 3.241(2) A.18 The hydrido
˚
ligands were located and refined crystallographically in both
˚
compounds [Re(1)-H(1) = 1.748(10) A, Re(2)-H(1) =
˚
˚
1.753(10) A in 3 and Re(1)-H(1) = 1.69(6) A, Re(2)-H(1) =
1.85(6) A in 4], and they exhibit the expected high-field
˚
resonance shift in the 1H NMR spectra [δ = -13.0 (d, 1H,
3J
1J
= 40 Hz, JP-H = 4 Hz) in 3 and -12.8 (s, 1H,
= 53 Hz) in 4]. An interesting, but not unprece-
4
195Pt-H
195Pt-H
dented feature of these hydride ligands is that they lie inside
the ring. We have observed this feature previously in five-
membered ReSn ring clusters that we prepared recently.19
Apparently, when the ring gets sufficiently large (five atoms),
the ligand crowding on the outside of the ring is sufficiently large
that the small hydrido ligand is accommodated more efficiently
on the inside of the ring. As in 2, there is a phenyl ring on the
Figure 5. ORTEP diagram of the molecular structure of HPtRe2-
(CO)8(P-t-Bu3)(μ-SbPh2)2(μ-H), 6, showing 30% probability
thermal ellipsoids. The hydrogen atoms on the ligands are
˚
platinum atom: Pt(1)-C(49) = 2.068(6) A in 3 and Pt(1)-
C(1) = 2.059(7) A in 4. The greatest difference between 3 and 4
˚
is the presence of a P(t-Bu)2H ligand on the Pt atom of 3 and a
SbPh3 ligand on the Pt atom of 4. The P(t-Bu)2H ligand was
evidently derived from a P(t-Bu)3 ligand in the Pt(P-t-Bu3)2
reagent. The formation of P(t-Bu)2H ligands from P(t-Bu)3
ligands has been observed previously and probably involves
formally the elimination of an isobutene from one of the tert-
butyl groups.20 We found that compound 4 could be converted to
3 in 65% yield by treatment with P(t-Bu)2H at 25 °C for 15 min.
Both rhenium atoms in compounds 3 and 4 are in the þ1
oxidation state and have 18-electron configurations. The platinum
atoms in 3and 4are in the þ2 oxidation state and have 16-electron
configurations.
When 1 was allowed to react with Pt(P-t-Bu3)2 in a hexane
solution at reflux (68 °C) under an atmosphere of hydrogen
(1 atm), three compounds were formed: 2 (14% yield), 4 (5%
yield), and HPtRe2(CO)8(P-t-Bu3)(μ-SbPh2)2(μ-H), 6 (21%
yield). Compound 6 has been characterized crystallographi-
cally, and an ORTEP diagram of its molecular structure is
shown in Figure 5. Compound 6 contains a five-membered
Re2Sb2Pt ring, similar to that in compounds 3 and 4. It is
composed of two Re(CO)4 groups and two bridging SbPh2
ligands with a HPt(P-t-Bu3) group between them.
˚
omitted for clarity. Selected interatomic bond distances (A) and
angles (deg) are as follows: Pt(1)-Sb(1) = 2.5854(5), Pt(1)-
Sb(2) = 2.6520(5), Re(1)-Sb(1) = 2.7722(5), Re(1)-Re(2) =
3.2742(4), Re(2)-Sb(2) = 2.8025(5), Pt(1)-H(2) = 1.60(9),
Re(1)-H(1) = 1.76(1), Re(2)-H(1) = 1.761(10), Pt(1)-P(1) =
2.320(2); Sb(1)-Pt(1)-Sb(2) = 92.017(16), Pt(1)-Sb(1)-Re(1) =
127.094(18), Pt(1)-Sb(2)-Re(2) = 114.513(17).
NMR spectrum [δ = -9.9 (1H, 1J195Pt-H = 912 Hz, 2JP-H
=
13 Hz), -13.0 (1H, 3J195Pt-H = 28 Hz, 4JP-H = 10 Hz)] with
suitable couplings to the platinum and phosphorus atoms. The
Re-Re bond distance in 6 is similar to those found in 3 and 4:
˚
Re(1)-Re(2) = 3.2742(4) A.
The reaction of 2 with 1 at 68 °C gave compound 4 in 18%
yield plus three previously reported compounds: Re2(CO)8-
(μ-SbPh2)2,9 7 (9% yield); Re2(CO)7(SbPh3)(μ-H)(μ-SbPh2),8 8
(12% yield); and Pt3(CO)3(t-Bu)3,11 9, 2.8 mg (5% yield).
Compound 7 was obtained previously from the thermal
decomposition of 1 in the absence of platinum, but that
reaction was performed at a much higher temperature (170 °C)
than the one reported here.9 Compound 8 were obtained
previously from the reaction of Re2(CO)8(Ph)(SbPh3)(μ-
SbPh2) with hydrogen at 125 °C.5 Compound 9 is readily
obtained when solutions of Pt(P-t-Bu3)2 are exposed to CO.11
Unlike 3 and 4, there is no phenyl group on the platinum
atom. In 7, the phenyl group was replaced with a terminal
hydride ligand, presumably derived from the hydrogen atmo-
sphere. The phenyl group was probably eliminated as benzene.
As in 3 and 4, there is a bridging hydride ligand across the
Re-Re bond on the inside of the five-membered ring. The
bridging hydride ligand was located and refined with restraints.
The terminal hydride ligand on platinum was located and
refined without restraints. The Pt-H bond distance is slightly
shorter than the Re-H bond distances: Pt(1)-H(2) = 1.60(9)
Five products were obtained in low yields when 2 was
thermally degraded under nitrogen at 100 °C: Re2(CO)8(μ-
SbPh2)2, 79 (6% yield); RePh(CO)4SbPh3, 108 (4%); Re2-
(CO)8[PtH(CO)(P-t-Bu3)](μ3-SbPh)(μ-SbPh2), 1110 (4%); 57
(4%); RePh(CO)4[PtH(CO)P(t-Bu)3](μ-SbPh2), 12 (7%). See
Scheme 2. The formation of benzene was confirmed by a 1H
NMR spectrum of the reaction solution.
Of the various products of this reaction, only compound
12 is new. Compound 12 was characterized crystallographi-
cally, and an ORTEP diagram of its molecular structure is
shown in Figure 6. Compound 12 can be viewed as a CO
adduct of 2, and indeed it can be obtained in a similar yield
when 2 is treated with CO at room temperature; see below.
The formation of 12 in this transformation must have been a
result of a CO scavenging process, the latter produced from
˚
˚
˚
A, Re(1)-H(1) = 1.76(1) A, Re(2)-H(1) = 1.761(10) A. Both
1
hydride ligands exhibit high-field resonance shifts in the H
(18) Masciocchi, N.; Sironi, A.; D’Alfonso, G. J. Am. Chem. Soc.
1990, 112, 9395–9397.
(19) Adams, R. D.; Captain, B.; Hollandsworth, C. B.; Johansson,
M.; Smith, J. L., Jr. Organometallics 2006, 25, 3848–3855.
(20) Adams, R. D.; Captain, B.; Pellechia, P. J. Organometallics 2007,
26, 6564–6575.

Article
Organometallics, Vol. 29, No. 17, 2010 3893
Scheme 2
Scheme 3
together by a bridging SbPh2 ligand. There is no metal-metal
˚
bond in 12: Pt Re = 4.622(1) A. We have recently shown
3 3 3
that the hydride and SbPh2 bridged rhenium-rhenium bond
in 8 can be opened by the addition of a hydride ligand.21 The
Pt-Sb and Re-Sb bond distances in 12 [Pt(1)-Sb(1) =
˚
˚
2.5890(3) A and Re(1)-Sb(1) = 2.7451(3) A] are slightly
longer than those in 2. A CO ligand was added to the
˚
platinum atom [Pt(1)-C(7) = 1.863(6) A], and lies cis to
the antimony atom Sb(1). The hydride ligand that bridges the
Pt-Re bond in 2 was shifted to a terminal position on the
platinum atom in 12 and lies cis to the Sb atom. The hydride
ligand was located and refined crystallographically. The
Pt-H bond distance is slightly shorter [Pt(1)-H(1) =
Figure 6. ORTEP diagram of the molecular structure of 12
showing 30% probability thermal ellipsoids. The hydrogen
atoms on the ligands are omitted for clarity. Selected intera-
˚
1.48(5) A] than the Pt-H bond distance found in 6. The
hydride ligand exhibits a high-field resonance shift, δ =
-3.8, with suitable couplings to the phosphorus and plati-
num atoms, 1J195Pt-H = 750 Hz, 2JP-H = 14 Hz. The bulky
P-t-Bu3 ligand on the platinum atom lies trans to the Sb
atom. Compound 11 also contains a HPt(P-t-Bu3)(CO)
group in which the hydride ligand lies cis to the Sb atom
and the P-t-Bu3 ligand lies trans to the Sb atom and has a
˚
tomic bond distances (A) and angles (deg) are as follows: Pt(1)-
C(7) =1.863(6),Pt(1)-P(1) = 2.3385(8), Pt1)-Sb(1) = 2.5890(3),
Pt(1)-H(1) = 1.48(5), Re(1)-C(1) = 2.229(3), Re(1)-
Sb(1) = 2.7451(3), Sb(1)-C(21) 2.147(3), Sb(1)-C(15) =
2.151(3); Pt(1)-Sb(1)-Re(1) = 120.097(9), C(7)-Pt(1)-P(1) =
105.13(16), C(7)-Pt(1)-Sb(1) = 98.62(16), P(1)-Pt(1)-Sb(1) =
155.75(2), C(7)-Pt(1)-H(1) = 172.9(18).
7
˚
similar Pt-Sb bond distance, 2.6100(12) A. The phenyl
other decomposing molecules of 2. Compound 12 consists of
a Re(CO)4Ph group and a HPt(P-t-Bu3)(CO) group held
(21) Adams, R. D.; Pearl, W. C., Jr. J. Organomet. Chem. 2010, 695,
937–940.

3894 Organometallics, Vol. 29, No. 17, 2010
Adams and Pearl
Figure 7. ORTEP diagram of the molecular structure of 14 showing 30% probability thermal ellipsoids. The hydrogen atoms on the
˚
ligands are omitted for clarity. Selected interatomic bond distances (A) and angles (deg) are as follows: Re(1)-Sb(1) = 2.7511(10),
Re(1)-Sb(2) = 2.8079(9), Re(2)-Sb(1) = 2.7482(9), Re(2)-Sb(2) = 2.8074(9), Re(3)-Sb(2) = 2.8439(10); Re(2)-Sb(1)-Re(1) =
105.31(3), Re(1)-Sb(2)-Re(2) = 102.26(3), Re(1)-Sb(2)-Re(3) = 117.92(3), Re(2)-Sb(2)-Re(3) = 118.34(3).
group in 12 is σ-bonded to the rhenium atom: Re(1)-C(1) =
increased sterics produced by the bulky Re(CO)5 group.
A number of compounds containing triply bridging SbPh
ligands were obtained from the reactions of 7 and Re2(CO)8-
(μ-H)(μ-SbPh2) with Pt(P-t-Bu3)2.10,15
˚
2.229(3) A. Interestingly, the phenyl group in 2 was σ-bonded
to the platinum atom. Evidently, the phenyl group was shifted
from Pt to Re in the course of the formation of 12. Note: the
coproduct 10 also has a phenyl group σ-bonded to a rhenium
atom. Compound 10 also contains an SbPh3 ligand, which
indicates that it is possible that the σ-phenyl group in 2 can
also be shifted back to the bridging SbPh2 ligand under these
conditions. The formation of 7 suggests that 2 can eliminate a
Re(CO)4SbPh2 fragment and two of these then combine to
form the dimer 7. The addition of a Re(CO)4SbPh2 group to
2 accompanied by the elimination of two phenyl groups
could account for the formation of 11. Compound 5 was
obtained previously from a sequence of reactions of Pt(P-t-
Bu3)2 and SbPh3 with 8. It appears that all of the components
essential to the formation of 5 are available in the decom-
position mixtures of 2.10
Discussion
In a previous study of the reaction of Pt(P-t-Bu3)2 with
HOs(CO)4(SnPh3), it was found that a Pt(P-t-Bu3) adduct
of HOs(CO)4(SnPh3), PtOs(CO)4SnPh3(P-t-Bu3)((μ-H), was
formed (see Figure 1), which included the formation of a
Pt-Os interaction with a bridging hydrido ligand and a
bridging CO ligand. The most important feature of the
reaction of 1 with Pt(P-t-Bu3)2 is the oxidative-addition of
a Sb-C bond of one of the phenyl groups of the SbPh3 ligand
to a Pt(P-t-Bu3) group formed by the loss of a P-t-Bu3 ligand,
eq 3. A Pt-Re bond was also formed together with a
bridging hydrido ligand and a bridging SbPh2 ligand. The
phenyl group that was cleaved from the Sb atom became a σ-
bonded ligand on the platinum atom. The cleavage of phenyl
groups from PPh3 and even SbPh3 has been observed on
many previous occasions.22,23
Seven compounds, 510 (9% yield), 79 (26%), 911 (71%), 1110
(7%), 12 (8%), 13 (13%), and 14 (18%), were obtained when 2
was allowed to react with CO at room temperature; see Scheme
3. Compound 9 was the major product by far. Compound 13
was obtained previously from the reaction of Re3(CO)12(μ-H)3
with Pt(P-t-Bu3)2.12 Compound 14 is new and was fully char-
acterized in this study. The molecular structure of 14 was
established by a single-crystal X-ray diffraction analysis, and
an ORTEP diagram of it is shown in Figure 7.
Compound 14 contains no platinum at all, but it does
contain three rhenium atoms. There are two Re(CO)4 groups
assembled into a Re2Sb2 rhombus by a bridging SbPh2 ligand
and a bridging SbPh ligand. The latter contains a pendant
Re(CO)5 group. The Re-Sb bond distances to the bridging
˚
SbPh2 group [Re(1)-Sb(1) = 2.7511(10) A, Re(1)-Sb(2) =
˚
˚
2.8079(9) A, and Re(2)-Sb(1) = 2.7482(9) A] are signifi-
cantly shorter than those to the SbPh group [Re(1)-Sb(2) =
We recently investigated the reaction of Pt(P-t-Bu3)2 with
compound 7 under hydrogen and observed the insertion of
˚
˚
2.8079(9) A and Re(2)-Sb(2) = 2.8074(9) A].TheRe(3)-Sb(2)
bond to the Re(CO)5 group is the longest of all, 2.8439(10) A.
˚
(22) Garrou, P. E. Chem. Rev. 1985, 85, 171–185.
The long Re-Sb bonds to Sb(2) are probably due to the
(23) Leong, W. K.; Chen, G. Organometallics 2001, 20, 2280–2287.

Article
Organometallics, Vol. 29, No. 17, 2010 3895
Pt(P-t-Bu3) groups into the SbPh bonds of the bridging
SbPh2 ligands, e.g., eq 4.10
this heterocyclic ring has considerable stability. At 100 °C,
compound 2 was degraded and a variety of higher nuclearity
species were formed by ligand scrambling, fragmentation,
and aggregation of the metal-containing fragments. Several
of these degradation products, 5, 7, and 11, were obtained by
the reaction of 2 with CO. Compound 12 is a CO adduct of 2
and can also be obtained from 2 by the direct addition of CO,
although the yield is not high. Interestingly, the phenyl group
was transferred from the platinum atom to the rhenium atom
in this process. This transfer may have been facilitated by the
addition of the CO ligand to the platinum atom, but the
mechanism of this transfer has not been ascertained in this
study.
The present work shows that the insertion of the Pt(P-t-
Bu3) group into the Sb-C bond of the SbPh3 ligand of 1 is
even more facile and occurs in this case at 25 °C. Interest-
ingly, 2 can react with 1 a second time under more forcing
conditions (68 °C) to form the five-membered heterocyclic
ring compound 4, which included a scavenged SbPh3 ligand
from the reaction mixture and the two dirhenium com-
pounds 7 and 8, eq 3. Although 7 can be obtained directly
from 1 at 170 °C, its formation here under milder conditions
is undoubtedly due to the ability of the platinum to facilitate
cleavage of the phenyl groups from the SbPh3 ligand. Two
other similar five-membered-ring compounds, 3 and 5, were
formed under slightly differing conditions, indicating that
Acknowledgment. This research was supported by the
National Science Foundation (CHE-0743190) and the
USC Nanocenter.
Supporting Information Available: CIF files for each of the
structural analyses are available. This material is available free
of charge via the Internet at http://pubs.acs.org.