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Reactions of Carbon Suboxide with Platinum(O) Complexes.

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Ir(I1)-Ir(I1) bonding was obtained.
We now report on the reaction of (1) with excess hexafluoro2-butyne, which leads to formation of a complex whose
chemical and spectroscopic data[21are consistent with formula (2)
The infrared spectra''] show five C O bands, and two groups
of C=C bands. The band at 1621 cm-' can be assigned
to a a-bonded alkyne, as in complex (1)13]. The two
other bands at 1830 and 1802 c m - ' are attributed to a T bonded a I k ~ n e [ ~
] . I9F-NMR spectrum[21confirms the existence of these two modes of coordination of the alkyne ligands. Furthermore the 'H-NMR spectruml2]shows that the
three lert-butylthiolato groups are nonequivalent.
(1) (0.587 g, ca. 0.5 mmol) was transferred to a thickwalled glass reaction vessel fitted with a Teflon stopcock.
After evacuation and cooling to -196"C, pentane (ca. 30
cm3) and 1.0 g hexafluorobut-2-yne (excess) were condensed
into the flask. The reaction mixture was then allowed to
warm-up slowly to room temperature and stirred for three
days. The solution was then evaporated under reduced pressure, and lemon yellow crystals obtained at - 2 0 ° C from 3
cm3 pentane. These were vacuum dried: yield 72%.
Received. J u l y 23. 1980 [Z 714 IE]
German Version Angew Chem Y3. 296 (1981)
J. Deuillers, J . J . Bonnet, D. de Montauzon, J .
Galv, R. Poilblanc, Inorg.
Chem. IY, 154 (1980).
121 IR (Hexadecane): vc,=2096 s, 2080 vs. 2051 vs, 2036 m, 2020 s: (CsBr):
y + = 1621 s, 1830 vs. 1802 vs; 'H-NMR (C,H,, TMS int.): 6 = 1.28, 1.19,
1.01; "F-NMR (C,H,, CF,COOH int.). 6 = 19.9. 18.9: m.p.= I19 'C.
[3] J. L. Dacidson, W. Harrnon. D. W. A . Sharp, G. A Srm, J . Organomel.
Chem. 4 6 C47 (1972): R. Marhieir. R. Poilblanc, ibrd. 142. 381 (1977).
141 D. R Russel, A Tucker, J Organomel. Chem. 125, 303 (1977): D. A . Clarke,
R. D. Kemmrrr. D. R. Russel, P. Tucker. hid. Y3. C37 (1975)
[ 5 ] Space group: Pi, 2 = 2 ; a=11.4892(17). b= 16.0528(25). c=10.2673(22)
a=98.764(17). !3=lOl.740(17), y=90781(12)y: V=18434A':
=241 g
cm -', pc,,=2.40 g cm ': 6657 Reflections (MoK,,-radraiion).from which
4672 have I > 3 ~ ( 0refined
to R = 3 499,.
Reactions of Carbon Suboxide
with Platinum(0) Complexes["]
By Gastone Paiaro and Lucian0 Pandolfo"'
Fig. 1. ORTEP-drawing of complex 12) in the crystal [5]: atoms F t . F2 and F9
are not shown. Most important bond lengths and angles: lrl-Ir2= 2.707(1),
111-lr3 = 3.730(1). lr2--Ir3=3.717(1), Irl-Sl=2.342(2),
Ir2-Sl = 2.339(3).
Ir3-SI =2.467(2), Ir3-S2=2.453(2),
Irl-Ct = 1.940(13),
CI-01 = 1 118(13), Irl-C20=2.085(tO),
1.889(10). C20-C22 = 1.291(15). C23-C24= I .244(14) A: lrl-Sl-lr2=
80.7. Sl-Ir3-C5=
Figure 1 shows the results of the X-ray structure analysis.
The geometry around the Ir" atoms (Irl and Ir2) is almost
the same as in (1).The simi!arity of the Irl-Ir2 distances in
( I ) and (2) (2.71 and 2.69 A respectively), strongly suggests
the existence of a metal-rnetal bond in (2). Substitution of a
C O group by a v-bonded C4Fhgroup at Ir'-atom (Ir 3) leads
to significant changes in the geometry of the remaining part
of the complex. The chair conformation of the ring formed
by Irl-Sl-Ir2-S3-1r3-S2
in (1) is transformed into a
"boat" conformation in (2). The rotation of Ir3 around the
S3-S2 axis is probably correlated with inversion of configuration at the S3 atom as well as with the formation of the
S1-Ir3 bond. The Ir3-S1,
and Ir3-S2
lengths are similar (Fig. 1). As a consequence, the S1 atom is
linked to all three Ir atoms and is thus tetracoordinated. For
the same reason, the coordination number of the Ir3 atom,
which was four in ( I ) , increases to five in (2). The geometry
around Ir3 can be described as a distorted trigonal bipyramid with S1, S3 and the center of C23-C24 bond in the
equatorial plane. The formation of the S1-Ir3 bond and the
related modifications of the structure are attributed to the
electron-withdrawing effect of the fluoroalkyne group
bonded to Ir3.
0 Yerlag Chemre GmbH,6940 Weinheim. 1981
Until now, no systematic study of the properties of carbon
as a ligand in transition metal complexes has
been reported. (1) has been regarded as an activated olefin in
reactions with transition metals. On the one hand, by analogy with C3S,121,
it reacts with C - - 0and C --Cgroups, but on
the other it can for example form diphenylketene-carbene
complexes by dissociating into CO and C,O moietie~'~'.
We report here on the reactions of ( I ) with the complexes
(PPh3)2Pt(C,H4) (2) and (PPh,),Pt(O,) (4). Reaction of (2)
with (1) affords the complex (31, whose IR spectrum exhibits
a strong ketene band (v=2080 c m - ' ) and a carbonyl band
( v = 1765 cm-I). Cyclic voltammetric measurements per-
formed in DMSO using a mercury-covered spherical gold
electrode indicate that (3)undergoes irreversible reduction at
a potential of - 1.8 V (us. SCE). Furthermore, potentiostatic
coulometry carried out at a mercury electrode indicate that
two electrons are involved in the overall cathodic process.
These results suggest that a metallocyclopropane structure[51
is probable for (3), formed by formal oxidative addition of
(1) to (2).
Reaction of (1) with (4) via 1,2-addition of the dioxygen
moiety across the C==C bond results in formation of a product whose elemental analysis and spectroscopic parameters
Prof. Dr. G . Paiaro. Dr. L. Pandolfo
Istituto dl Chimica Analitica. Universita di Padova
Via F Marzolo I . 1-35 100 Padova (Italy)
This work was supported b y C.N.R. (Roma).
S 02.50/0
Angew Chem. Ini. Ed. Engl. 20 (lY81) Nu. 3
are consistent with the structure (5)[']. The IR spectrum of
(5) exhibits strong ketene and carbonyl bands ( v = 2080 and
1625 c m - ' resp.): a peroxide 0-0 bond could not be observed either by IR-spectroscopy (no band at 825 cm-') or
by an iodine testl'l. (5) isomerizes in solution giving a known
compound [(PPh3),Pt(O),]C3Oz having an intense band at
v = 1685 cm-1[81.
These types of reactions of carbon suboxide (1) with compounds (2) and (4) are of interest because they lead to complexes in which there is a "free" ketene group and indicate
that the dioxygen ligand in (4) attacks C30r directly.
All solvents were degassed and manipulations carried out
under an argon atmosphere. (1) was prepared by dehydration of malonic acid with P4Hlo.
(3): (1) (0.25 mmol) is passed into a solution of (2) (0.19
mmol) in 10 cm3 ether at - 20 "C; white microcrystalline (3)
is filtered off. Yield 37%, m.p.= 128-129°C (decomp.).
(5): (1) (2.8 mmol) is passed into a solution of (4) (2.1 g, 2.8
mmol) in 30 cm3 CH2C12;white microcrystalline (S) is filtered off and washed with cold CH2ClZ. Yield 41%,
m. p. = 130-132 "C (decomp.). Elemental analysis corresponded to (S) .CH2C12.
Received: June 9, 1980 [Z 713a IE]
German version: Angew. Chem. 93, 294 (1981)
CAS Registry Numbers:
( I ) , 504-64-3: (2). I21 20-1 5-9; 13). 76900-29-3, (4). 29894-57-3; (5). 76879-99-7
[ I ] See e g : T. Kappe. E. Ziegler, Angew. Chem 85, 529 (1974); Angew. Chem.
Int. Ed. Engl. 13, 491 (1974); L. D. Brown, W. N . Lipscomb, J. Am. Chem.
SOC.99. 3968 (1977).
121 A. P. Ginsberg. W. E Silverfhorn. Chem. Commun. 1969, 823.
[3] P Hong. N . Nishii. K. Sonogashira, N . Hagiharu. J. Chem. SOC.Chem. Commun. 1972. 993; H. Ueda, Y. Kai, N . Yasuoka, N. Kusui. Bull. Chem. Soc.
Jpn. 5 0 , 2250 (1977).
141 Rhodium([) and Nickel(0) complexes react in this manner: C. Paiuro, L. Pandolfo. P. Segalu, XI1 Natl. Congr. of Inorg. Chem., Trieste. ll-15th Sept.
[ S ] K. Schorpp. W. Beck, Z. Naturforsch. B 28, 738 (1973).
[6] A similar reaction has been reported recently for activated acetylenes, H. C.
Clark. A. 8 Goel, C . S. Wong, J. Am. Chem. SOC.100, 6241 (1978).
and (Cy,P)PtO2 oxidize coordinated phosphane derivatives; see
171 (Ph>Et)>PtO>
also A Sen. J. Halpern, J. Am. Chem. SOC.99, 8337 (1977).
[Sl This compound can be obtained directly from solutions of (PPh&Pt(O,) and
' 2 3 0 2 ; K. S Kolomnikov, Y. D. Koreshkov, T S. Lobeeva, M . E. Volpin, Izv.
Akad Nauk. SSSR. Ser. Ktum. 1972. 1181.
By Gaslone Paiaro and Lucian0 PandolfoI-1
As part of our studies on the coordinating properties of
carbon suboxide (1) with transition metals['], we examined
the reaction of rhodium(1) complexes with (1).
Reaction of (PPh,),RhCl (2) with (1) in benzene gives
(3) in addition to polymers derived
from CzO[2J.
Prof. Dr. G. Paiaro. Dr. L. Pandolfo
Istituto di Chimica Analilica, Universita di Padova
Via F Marzolo 1, 1-35 100 Padova (Italy)
(PPh,),(CO)RhCl+ PPh,
+ l/n(C20),
The course of the reaction in CHzClzhas been followed by
IR spectroscopy: an intense band at 2080 cm - ' ( yel,,,)soon
appears but decreases in intensity and eventually disappears
while a band at 1970 cm-' ( vco) increases. Another band at
2210 cm-' reaches its maximum intensity after 1 h and completely disappears after 24 h. These results suggest that the
reaction proceeds via nucleophilic attack of a tricoordinated
rhodium species on the electrophilic C-1 of (1). In this way
(1) is cleaved into CO and CzO, producing the thermodynamically stable carbonyl rhodium complex (3)[31.
The binuclear [(C8H,4)2RhC1]z(4) reacts with (1) in toluene to give the brick-red complex (5).
G O z + I(CnH,4)2RhCI12 l/n[CsH,4)(CO)Rh(C~O)C11,+ C8Ht4
Compound (5) is stable and insoluble in most organic solvents; only chloro-bridge splitting reagents such as pyridine
"dissolve" it.
The IR spectrum of (5) contains bands which can be assigned to a terminal carbonyl group (v=2010 cm-'), an
Rh-Cl bridge ( v = 303 cm - I ) , a ketene ( v = 2080 cm - ') and
cyclooctene ligand ( v = 2935, 2800 cm - I); these assignments were confirmed by 'H-NMR spectroscopy ([D6]-dimethylsulfoxide; S=5.51 (2H), 2.51 (4H), 1.43 (8H)). Potentiostatic coulometry ( - 1.75 V us. SCE) carried out at a platinum electrode, indicates that three electrons are involved in
the overall cathodic reaction of (S). On the basis of these results the structure of (5) must consist of a polymeric rhodium(m) complex having chlorine and carbene bridges as
shown in ( S U ) [ ~ ~ .
Carbon suboxide (1)does not react with [(CsH,2)RhC1]2or
[(CzH4)zRh(C5H5)]in CH2Clz solution. The type of reaction
described here is of particular interest in relation to catalytic
All reactions were carried out under an atmosphere of argon.
(1) was prepared by dehydration of malonic acid with
(3): (1) (2.3 mmol) is passed into a solution of (2) (2.27
mmol) in 100 cm3 benzene at room temperature. A red solid
precipitates and is filtered off and crystallized from acetone.
m. p. = 195 "C.
(5): (1) (1.45 mmol) is passed into a solution of (4) (1.28
mmol) in 50 cm3 toluene at 0°C; the solution becomes red.
After 24 h the solution i s colorless and a red solid is formed.
After elemental analysis this corresponds to (S) .C7H8;yield
This work was supported by C.N.R. (Roma).
Angew. Chem. Int. Ed Engl. 20 (1981) No. 3
+ (PPh,),RhCI
Reactions of Carbon Suboxide
with Rhodium(1) Complexes[**]
0 Verlag Chemie GmbH, 6940 Weinheim, 1981
Received: June 30, 1980 [Z 713 b IE]
German version: Angew. Chem. 93. 295 (1981)
S 02.50/0
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platinum, reaction, complexes, suboxide, carbon
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