Heteronuclear triangular clusters of the type [Pt2M(μ3-η1:η1:η 2-PhC≡CC≡CPh)(CO)5(PPh3) 2] (M= Fe or Ru)

Article abstract of DOI:10.1021/om970865u

The 46-electron heteronuclear clusters [Pt₂M-(μ₃-η¹:η ¹:η²-PhC≡CC≡CPh)(CO)₅(PPh ₃)₂] (M = Fe or Ru) are formed in moderate yield by treating [Pt(η²-PhC≡ CC≡CPh)(PPh₃)₂] with [Fe(CO)₅] or [Ru₃(CO)₁₂] in refluxing toluene. The Pt₂Fe and Pt₂Ru clusters are isostructural, being composed of two Pt(CO)(PPh₃) units and a M(CO)₃ group linked by two Pt-Fe or Pt-Ru bonds with the μ₃-diyne coordinated through only one C≡C bond.

Full text of DOI:10.1021/om970865u

Organometallics 1998, 17, 775-778
775
Heter on u clea r Tr ia n gu la r Clu ster s of th e Typ e
[P t2M(µ3-η1:η1:η2-P h CtCCtCP h )(CO)5(P P h 3)2] (M )
F e or Ru )
Shinsaku Yamazaki,*,† Antony J . Deeming,*,‡ and Despo M. Speel‡
Chemistry Laboratory, Kochi Gakuen College, 292 Asahi Tenjin-Cho, Kochi 780, J apan, and
Department of Chemistry, University College London, 20 Gordon Street,
London WC1H 0AJ , U.K.
Received October 6, 1997
Summary: The 46-electron heteronuclear clusters [Pt2M-
(µ3-η1:η1:η2-PhCtCCtCPh)(CO)5(PPh3)2] (M ) Fe or Ru)
are formed in moderate yield by treating [Pt(η2-PhCt
CCtCPh)(PPh3)2] with [Fe(CO)5] or [Ru3(CO)12] in re-
fluxing toluene. The Pt2Fe and Pt2Ru clusters are
isostructural, being composed of two Pt(CO)(PPh3) units
and a M(CO)3 group linked by two Pt-Fe or Pt-Ru
bonds with the µ3-diyne coordinated through only one
CtC bond.
In tr od u ction
Alkynes can supply up to six electrons to up to four
metal centers and can assist in cluster reinforcement.
Alkyne clusters can undergo redox processes without a
change in cluster nuclearity, and 1,3-diynes, with an
even greater capacity to supply electrons, have been
used likewise. For example, the complexes [{Co2-
(CO)6}2(µ-diyne)]1 and [{Ni2Cp2}2(µ-diyne)]2 undergo two
reversible metal-centered one-electron reductions (CV
and ESR studies of frozen solutions).3 It is noted that
in using 1,3-diynes with clusters, C-C bond cleavage
can occur. Thus, the reaction of [Os3(CO)10(MeCN)2]
with PhCtCCtCPh gives [Os3(CO)10(µ3-PhCtCCt
CPh)], which loses a CO ligand to afford the cluster
[Os3(µ3-CtCPh)(µ2-CtCPh)(CO)9].4 Coupling of alkynyl
ligands can also occur. For example, bis(alkynyl) com-
plexes of iron(II),5 osmium(II),6 or rhodium(III)7 can lead
to coordinated butenynes or butadiynes by oxidative
coupling. A diyne trimer is formed from diyne in a
reaction induced by [Ru4(µ3-PPh)(CO)13].8 In spite of the
scope for transformations of this kind, this study was
F igu r e 1. Molecular structure of 1. Selected distances (Å)
and angles (deg): Pt(1)-C(1) 2.036(8), Pt(1)-C(2) 2.041-
(7), Pt(1)-P(1) 2.273(2), Pt(1)-P(2) 2.279(2), C(1)-C(2)
1.305(11), C(1)-C(5) 1.437(11), C(2)-C(3) 1.389(11), C(3)-
C(4) 1.200(11), C(4)-C(11) 1.439(11), C(1)-Pt(1)-C(2) 37.3-
(3), C(2)-Pt(1)-P(1) 108.2(2), C(1)-Pt(1)-P(2) 110.9(2),
C(2)-C(1)-C(5) 140.7(7), C(1)-C(2)-C(3) 146.7(8), C(2)-
C(3)-C(4) 176.4(9), C(3)-C(4)-C(11) 176.5(9).
aimed at coordinating one CtC group of a diyne ligand
to a metal center and using the remaining one to bind
to incoming metallic reagents to give bridging diynes
en route to heterometallic clusters. Thus, [Pt(η2-PhCt
CCtCPh)(PPh3)2] was treated with reagents such as
[Fe(CO)5], [Ru3(CO)12], and other carbonyl complexes in
an attempt to bind the incoming metal atoms to the free
CtC bond. Unexpectedly, diyne heterometallic clusters
in which one CtC bond remained uncoordinated were
obtained and no C-C bond cleavage was observed.
† Kochi Gakuen College.
‡ University College London. D.M.S. has previously published under
her maiden name Despo M. Michaelidou. A.J .D. may be contacted by
e-mail: a.j.deeming@ucl.ac.uk.
(1) Fronczek, F. R.; Erickson, M. S. J . Chem. Crystallogr. 1996, 25,
737.
(2) Tilney-Bassett, J . F. J . Chem. Soc. 1961, 577.
(3) (a) Osella, D.; Rossetti, R.; Nervi, C.; Ravera, M.; Moretta, M.;
Fiedler, J .; Posp´ısil, L.; Samuel, E. Organometallics 1997, 16, 695. (b)
Osella, D.; Milone, L.; Nervi, C.; Ravera, M. J . Organomet. Chem. 1995,
488, 1.
(4) (a) Deeming, A. J .; Felix, M. S. B.; Bates, P. A.; Hursthouse, M.
B. J . Chem. Soc., Chem. Commun. 1987, 461. (b) Deeming, A. J .; Felix,
M. S. B.; Nuel, D. Inorg. Chim. Acta 1993, 213, 3.
(5) Field, L. D.; George, A. V.; Purches, G. R.; Slip, I. H. M.
Organometallics 1992, 11, 3019.
(6) Gotzig, J .; Otto, H.; Werner, H. J . Organomet. Chem. 1985, 287,
247.
(7) Werner, H.; Gevert, O.; Haquette, P. Organometallics 1997, 16,
803.
Resu lts a n d Discu ssion
The diyne complex [Pt(PhCtCCtCPh)(PPh3)2] (1) is
formed quantitatively by treatment of [Pt(PPh3)4] with
the diyne. IR absorptions at 2161 and 1731 cm-1 are
assigned to free and coordinated CtC bonds, respec-
tively. The single-crystal X-ray structure of 1 confirms
the original proposal9 that only one of the two CtC
bonds is coordinated (Figure 1). The coordination
(8) Corrigan, J . F.; Doherty, S.; Taylor, N. J .; Carty, A. J . Organo-
metallics 1992, 11, 3160.
(9) Heyns, J . B. B.; Stone, F. G. A. J . Organomet. Chem. 1978, 160,
337.
S0276-7333(97)00865-0 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 01/23/1998

776 Organometallics, Vol. 17, No. 4, 1998
Notes
Sch em e 1
geometry at platinum is close to planar, the dihedral
angle between the Pt(1)P(1)P(2) and the Pt(1)C(1)C(2)
planes being 3.5°. Although the coordinated alkyne is
unsymmetrical, the coordination geometry at Pt is
essentially symmetrical; the Ph group at C(1) and the
PhC2 group at C(2) are exerting similar effects.
F igu r e 2. Molecular structure of 2 in 2‚C6H6. Selected
distances (Å) and angles (deg): Pt(1)-Fe(1) 2.609(3), Pt-
(2)-Fe(1) 2.606(3), Pt(1)-Pt(2) 2.939(2), Pt(1)-C(1) 2.097-
(12), Pt(2)-C(2) 2.073(12), Fe(1)-C(1) 2.139(12), Fe(1)-
C(2) 2.097(12), Pt(1)-P(1) 2.329(4), Pt(2)-P(2) 2.344(4),
Pt(1)-C(21) 1.902(14), Pt(2)-C(31) 1.90(2), C(1)-C(2) 1.43-
(2), C(3)-C(4) 1.20(2), C(2)-C(1)-C(301) 129.0(11), C(1)-
C(2)-C(3) 127.9(11), C(2)-C(3)-C(4) 170(2), C(3)-C(4)-
C(311) 174(2). The structure of 3‚C6H6 is closely similar
with selected distances (Å) and angles (deg): Pt(1)-Ru(1)
2.694(2), Pt(2)-Ru(1) 2.699(2), Pt(1)-Pt(2) 2.9595(13), Pt-
(1)-C(1) 2.073(14), Pt(2)-C(2) 2.06(2), Ru(1)-C(1) 2.28-
(2), Ru(1)-C(2) 2.19(2), Pt(1)-P(1) 2.327(5), Pt(2)-P(2)
2.346(4), Pt(1)-C(21) 1.89(2), Pt(2)-C(31) 1.86(3), C(1)-
C(2) 1.47(3), C(3)-C(4) 1.22(2), C(2)-C(1)-C(301) 127.6-
(13), C(1)-C(2)-C(3) 126(2), C(2)-C(3)-C(4) 166(2), C(3)-
C(4)-C(311) 177(2).
Treatment of 1 with [Fe(CO)5] in refluxing toluene
gave the product [Pt2Fe(µ3-η1:η1:η2-PhCtCCtCPh)-
(CO)5(PPh3)2] (2) as red crystals (62%) (Scheme 1). 13C-
{1H} NMR spectra are consistent with one CtC re-
maining uncoordinated; two of the four acetylenic
carbon atoms give signals at δ 98.7 and 98.3 (free CtC)
and two at δ 149.0 and 166.0 (coordinated CtC).
Crystals of 2 suitable for XRD were obtained in two
forms: triclinic 2‚C6H6 from a benzene-acetone solution
and monoclinic 2‚CHCl3 from a chloroform-hexane
solution. Their molecular structures shown in Figures
2 and 3, respectively, are superficially similar with the
diyne µ3-coordinated to a Pt2Fe triangle in the common
parallel manner8,10 with two Pt-C σ-bonds and an η2-
interaction to Fe. The system might be considered to
result from coordination of the diplatinacyclobutadiene
783 Hz coupling is across a full Pt-Pt bond in this case
and is approximately 4 times the value for 2. The Pt-
Pt bond length in [Pt2(CO)2(PPh3)2(µ-η1:η1-MeO2CCtC-
CO2Me)] is 2.6354(8) Å,11 typically of platinum(I) dimers
and considerably less than that for 2.
compound, PtI (CO)2(PPh3)2(µ-η1:η1-PhCtCCtCPh), to
2
a Fe(CO)3 group to form a 46-electron system. This Pt2
unit would be closely related to the known platinum(I)
compound [Pt2(CO)2(PPh3)2(µ-η1:η1-MeO2CCtCCO2-
Me)].11 There are clear structural differences between
the two crystalline forms, 2‚C6H6 and 2‚CHCl3. The
PPh3 ligands have different conformations, and the Fe-
(CO)3 groups are twisted in a turnstile manner going
from one structure to the other, but most significantly
there are pronounced differences in the metal-metal
distances. The Pt-Pt distance in 2‚C6H6 is 2.939(1) Å,
which is elongated to 3.072(1) Å in 2‚CHCl3. As the Pt-
Pt distance is increased, there is an associated but
smaller reduction in the Pt-Fe distances, which are
2.609(3) and 2.606(3) Å in 2‚C6H6 which are reduced to
2.594(2) and 2.598(2) Å in 2‚CHCl3. The difference in
the Pt-Pt distances (∆ ) 0.133 Å) indicates that there
is either no Pt-Pt bond or that this bond is weak and
easily deformed. The values of J PtP are 3500 and 192
Hz for one 31P nucleus and 3608 and 208 Hz for the
other, the smaller values being couplings between the
31P nuclei and the distant 195Pt nuclei. The correspond-
ing J PtP values for the related dimer [Pt2(CO)2(PPh3)2(µ-
η1:η1-MeO2CCtCCO2Me)] are 2409 and 783 Hz.11 The
The corresponding ruthenium complex [Pt2Ru(µ3-η1:
η1:η2-PhCtCCtCPh)(CO)5(PPh3)2] (3) was obtained
similarly (19% yield) from 1 and [Ru3(CO)12] in refluxing
toluene. The crystals of 3‚C6H6, grown from benzene-
acetone, are isomorphous with the corresponding Pt2-
Fe cluster 2‚C6H6. The structures are very similar,
apart from the longer Pt-Ru distances of 2.694(2) and
2.699(2) Å. These results seem to indicate that the reac-
tions of 1 with [Fe(CO)5] or [Ru3(CO)12] do not require
a free CtC bond because only one CtC is chemically
involved. Consistent with this, the reaction of [Pt(Ph-
CtCPh)(PPh3)2] with [Fe(CO)5] gives, among other
products, the complex [Pt2Fe(µ3-η1:η1:η2-PhCtCPh)-
(CO)5(PPh3)2] (4), which is under investigation. Prelim-
inary results indicate that 4 is related to 2, but the
stereochemistries at the two Pt atoms are different in
4.
Exp er im en ta l Section
Syn th eses of [P t(η2-P h CtCCtCP h )(P P h 3)2] (1). By a
method analogous to that using [Pt(C2H4)(PPh3)2],9 a solution
of [Pt(PPh3)4] (1.50 g, 1.2 mmol) and PhCtCCtCPh (0.25 g,
1.2 mmol) in CH2Cl2 (20 cm3) was stirred under N2 at 20 °C
for 10 min. The volume was decreased by one-half, and
addition of hexane gave 1 as orange prisms (0.96 g, 99%). Anal.
Calcd for C52H40P2Pt: C, 67.74; H, 4.37. Found: C, 68.43; H,
4.56. IR (Nujol): ν(CtC) 2161 m (noncoordinated), 1731 m
(10) (a) Bruce, M. I.; Skelton, B. W.; White, A. H.; Zaitseva, N. N.
Aust. J . Chem. 1996, 49, 155. (b) Bruce, M. I.; Low, P. J .; Werth, A.;
Skelton, B. W.; White, A. H. J . Chem. Soc., Dalton Trans. 1996, 1551.
(c) Bruce, M. I.; Zaitseva, N. N.; Skelton, B. W.; White, A. H. Inorg.
Chim. Acta 1996, 250, 129.
(11) (a) Koie, Y.; Shinoda, S.; Saito, Y.; Fitzgerald, B. J .; Pierpont,
C. G. Inorg. Chem. 1980, 19, 770. (b) Koie, Y.; Shinoda, S.; Saito, Y.
Inorg Chem. 1981, 20, 4408.

Notes
Organometallics, Vol. 17, No. 4, 1998 777
F igu r e 3. Molecular structure of 2 in 2‚CHCl3. Selected distances (Å) and angles (deg): Pt(1)-Fe(1) 2.594(2), Pt(2)-Fe-
(1) 2.598(2), Pt(1)-Pt(2) 3.072(1), Pt(1)-C(1) 2.091(14), Pt(2)-C(2) 2.065(13), Fe(1)-C(1) 2.168(12), Fe(1)-C(2) 2.098(14),
Pt(1)-P(1) 2.336(4), Pt(2)-P(2) 2.335(3), Pt(1)-C(21) 1.93(2), Pt(2)-C(31) 1.89(2), C(1)-C(2) 1.43(2), C(3)-C(4) 1.19(2),
C(2)-C(1)-C(301) 125.8(12), C(1)-C(2)-C(3) 123.8(13), C(2)-C(3)-C(4) 174(2), C(3)-C(4)-C(311) 177(2).
(coordinated) cm-l
.
13C{1H} NMR (CDCl3): diyne δ 108.1 (d,
X-r a y Str u ctu r e Deten n in a tion of 1, 2‚C6H6, 2‚CHCl3,
a n d 3‚C6H6. Intensity data collected by ω-2θ scans at 18 °C
on a Nicolet R3v/m instrument using Mo KR radiation (λ )
0.710 73 Å) were corrected for Lorentz and polarization effects
and for absorption by semiempirical methods based on Ψ-
scans. Structure solutions were performed by direct methods
using SHELXL-93,12 with refinement by full-matrix least-
squares on Fo2. All non-H atoms were refined anisotropically
with H-atoms in calculated positions riding on C-atoms with
C-H fixed at 0.96 Å. (a) Crystal data for 1: C52H40P2Pt, M )
921.87, colorless crystal, 0.65 × 0.50 × 0.20 mm, triclinic, P1h,
a ) 12.061(6) Å, b ) 13.066(6) Å, c ) 15.809(6) Å, R ) 68.82-
(3)°, â ) 89.03(4)°, γ ) 66.12(3)°, V ) 2100(2) Å3, Z ) 2, Dc )
1.458 g cm-3, F(000) ) 920, µ(Mo KR) ) 34.52 cm-1, R1 )
0.0519, wR2 ) 0.141, goof ) 1.037 for 7414 reflections in the
range 5° e 2θ e 50° with I > 2σ(Io) refining 496 parameters.
(b) Crystal data for 2‚C6H6: C63H46FeO5P2Pt2, M ) 1390.97,
red plate, 0.70 × 0.38 × 0.10 mm, triclinic, P1h, a ) 13.564(9)
Å, b ) 13.914(12) Å, c ) 15.41(2) Å, R ) 79.29(7)°, â ) 85.51-
J PC ) 67.9 Hz, J PtC ) 281.2 Hz, C1,2), 82.2 (dd, J PC,trans )
12.7 Hz, J PC,cis ) 6.7 Hz, C3), 103.8 (d, J PC ) 6.4 Hz). 31P-
{1H} NMR (CDCl3): δ 23.9 (J PP ) 24.7 Hz, J PtP ) 3598 Hz),
23.6 (J PP ) 24.7 Hz, J PtP ) 3377 Hz).
Syn th esis of [P t2F e(µ3-η1:η1:η2-P h CtCCtCP h )(CO)5-
(P P h 3)2] (2). A mixture of [Fe(CO)5] (0.185 g) and 1 (0.65 g)
in toluene (50 cm3) under N2 was refluxed for 30 min to give
a deep orange solution. TLC (SiO2; eluent CH2Cl2-hexane)
gave a deep orange band, which was extracted with CH2Cl2.
Slow evaporation of a CH2Cl2-hexane solution gave orange
microcrystals of 2 (0.45 g, 62% based on Pt). Anal. Calcd for
C54H40FeO5P2Pt2‚(CH2Cl2)0.5: C, 50.95; H, 3.03. Found: C,
50.44; H, 2.97. IR (Nujol): ν(CO), 2030 vs, 1988 vs, 1941 vs
cm-1
.
13C{1H} NMR (CDCl3): δ 166.0 (d, J PC ) 1.6 Hz,
PhC1dC, coord), 149.0 (m, PhCdC2, coord), 98.7 (dd, C3tCPh,
uncoord), 98.3 (d, J PC ) 1.6 Hz, CtC4Ph, uncoord), 216.5 (dd,
J
PC,cis ) 4.1 Hz, J PtC ) 10 Hz, FeCO), 196.0 (d, J PC ) ca. 8
Hz, FeCO), 194.0 (d, J PC ) 8.2 Hz, PtCO, 195Pt coupling
undetected). 31P{1H} NMR (CDCl3): δ 14.8 (J PtP ) 3500, 192
Hz), 22.2 (J PtP ) 3608, 208 Hz). Recrystallization from
benzene-acetone gave single crystals of 2‚C6H6 for single-
crystal X-ray diffraction. Crystals of 2‚CHCl3 were likewise
precipitated from a chloroform-hexane mixture.
(7)°, γ ) 86.45(6)°, V ) 2846(4) Å3, Z ) 2, Dc ) 1.623 g cm-3
,
F(000) ) 1352, µ(Mo KR) ) 52.58 cm-1, R1 ) 0.0555, wR2 )
0.145, goof ) 1.090 for 7131 reflections in the range 5° e 2θ e
45° with I > 2σ(Io) refining 658 parameters. (c) Crystal data
for 2‚CHCl3: C58H40Cl3FeO5P2Pt2, M ) 1431.22, red plate, 0.63
× 0.40 × 0.12 mm, monoclinic, P21/c, a ) 13.152(5) Å, b )
23.707(13) Å, c ) 18.407(10) Å, â ) 103.31(4)°, V ) 5584(5)
Å3, Z ) 4, Dc ) 1.702 g cm-3, F(000) ) 2764, µ(Mo KR) ) 55.00
cm-1, R1 ) 0.0556, wR2 ) 0.135, goof ) 1.114 for 8107
reflections in the range 5° e 2θ e 47° with I > 2σ(Io) refining
629 parameters. (d) Crystal data for 3‚C6H6: C63H46O5P2Pt2-
Ru, M ) 1436.19, red triclinic plate, 0.55 × 0.28 × 0.08 mm,
P1h, a ) 13.581(12)°, b ) 14.048(10)°, c ) 15.346(9) Å, R )
79.32(5)°, â ) 85.49(6)°, γ ) 85.88(6)°, V ) 2863(3) Å3, Z ) 2,
Dc ) 1.666 g cm-3, F(000) ) 1388, µ(Mo KR) ) 52.37 cm-1, R1
Syn th esis of [P t2Ru (µ3-η1:η1:η2-P h CtCCtCP h )(CO)5-
(P P h 3)2] (3). A suspension of 1 (0.25 g) and [Ru3(CO)12] (0.175
g) in toluene (15 cm3) was refluxed for 10 min to give a deep
orange solution. Removal of the solvent and TLC separation
(eluent CH2Cl2-hexane) gave a deep orange band resulting
in 3 as orange microcrystals (0.070 g, 19%). Anal. Calcd for
C
54H40O5P2Pt2Ru: C, 50.41; H, 2.97. Found: C, 50.27; H, 2.91.
IR (Nujol): ν(CO) 2044 vs, 2010 vs, 1964 s, 1944 cm-1
.
13C{1H}
NMR (CDCl3): broad signals, δ 200.6 (RuCO, 195Pt satellites
just apparent), 194.7, 192.4 (PtCO, 195Pt satellites unresolved),
100.5, 98.0 (uncoordinated CtC), other signals unassigned.
Single crystals suitable for XRD were obtained from benzene-
acetone.
(12) Sheldrick, G. M. SHELXL-93; University of Go¨ttingen: Go¨t-
tingen, Germany, 1993.

778 Organometallics, Vol. 17, No. 4, 1998
Notes
) 0.0539, wR2 ) 0.138, goof ) 1.005 for 5275 reflections in
the range 5° e 2θ e 45° with I > 2σ(Io) refining 613
parameters.
Su p p or tin g In for m a tion Ava ila ble: Fully labeled dia-
grams and tables of crystallographic data, data collection,
solution, and refinement details, positional and thermal
parameters, and bond distances and angles for 1, 2, and 3 (50
pages). Ordering information is given on any current mast-
head page.
Ack n ow led gm en t . We thank Professor N. Ya-
masaki (Research Institute of Hydrothermal Sciences,
Kochi University) and M. Ochi for their generous
provision of the 400 MHz J eol Lambda NMR spectra at
the Center for J oint Research and Development, Kochi
University, and the EPSRC for support.
OM970865U