[Pt(C≡CR)4]2- as double alkynylation reagents: Facile formation of binuclear Bis(μ-alkynide) (M-Pt) and unsymmetrical trinuclear double Bis(μ-alkynide) (M-Pt-Pt) complexes

Article abstract of DOI:10.1021/om990753y

Treatment of (NBu₄)₂[Pt(C≡CR)₄]·2H₂O (R = t-Bu, 1a; SiMe₃, 1b; Ph, 1c) with 1 equiv of the dicationic solvento species [Cp*M(PEt₃)(acetone)₂](ClO₄)₂ (M = Rh, Ir) results in double alkynyl transfer to give the binuclear compounds [(PEt₃)Cp*M(μ-1κC^α:η ²-C≡CR)₂Pt(C≡CR)₂] (M = Rh, 2; Ir, 3), in which the organometallic unit cis-Pt(C≡CR)₂ is unusually stabilized by η²-bis(alkyne) interactions, as has also been confirmed for the related binuclear complex [(PPh₃)Cp*Rh(μ-1κC^α:η ²-C≡CSiMe₃)₂Pt(C≡CSiMe ₃)₂], 4b, which has been prepared analogously. These binuclear tetraalkynyl complexes can be used as precursors to unusual bis-(double-alkynide)-bridged trinuclear derivatives [(PEt₃)Cp*M(μ-1κC^α:η ²-C≡CR)₂Pt(μ-2κC^α: η²-C≡CR)₂Pt(C₆F₅) ₂] (M = Rh, 5; Ir, 6) by displacement reactions of thf from [cis-Pt(C₆F₅)₂(thf)₂]. An X-ray diffraction study confirms that in complex 5b (R = SiMe₃) the mononuclear rhodium fragment Cp*Rh(C≡CSiMe₃)₂(PEt₃) acts as a chelating bidentate ligand toward the alkynyl-bridged diplatinum organometallic unit Pt(μ-1κC^α:η²-C≡CSiMe) ₂-Pt(C₆F₅)₂.

Full text of DOI:10.1021/om990753y

490
Organometallics 2000, 19, 490-496
[P t(CtCR)4]2- a s Dou ble Alk yn yla tion Rea gen ts: F a cile
F or m a tion of Bin u clea r Bis(µ-a lk yn id e) (M-P t) a n d
Un sym m etr ica l Tr in u clea r Dou ble Bis(µ-a lk yn id e)
(M-P t-P t) Com p lexes
J esu´s R. Berenguer,† Eduardo Eguiza´bal,† Larry R. Falvello,‡ J uan Fornie´s,*,‡
Elena Lalinde,*,† and Antonio Mart´ın‡
Departamento de Quı´mica, Universidad de La Rioja, 26001, Logron˜o, Spain, and
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cientı´ficas,
50009 Zaragoza, Spain
Received September 24, 1999
Treatment of (NBu4)2[Pt(CtCR)4]‚2H2O (R ) t-Bu, 1a ; SiMe3, 1b; Ph, 1c) with 1 equiv of
the dicationic solvento species [Cp*M(PEt3)(acetone)2](ClO4)2 (M ) Rh, Ir) results in double
alkynyl transfer to give the binuclear compounds [(PEt3)Cp*M(µ-1κCR:η2-CtCR)2Pt(CtCR)2]
(M ) Rh, 2; Ir, 3), in which the organometallic unit “cis-Pt(CtCR)2” is unusually stabilized
by η2-bis(alkyne) interactions, as has also been confirmed for the related binuclear complex
[(PPh3)Cp*Rh(µ-1κCR:η2-CtCSiMe3)2Pt(CtCSiMe3)2], 4b, which has been prepared analo-
gously. These binuclear tetraalkynyl complexes can be used as precursors to unusual bis-
(double-alkynide)-bridged trinuclear derivatives [(PEt3)Cp*M(µ-1κCR:η2-CtCR)2Pt(µ-2κCR:
η2-CtCR)2Pt(C6F5)2] (M ) Rh, 5; Ir, 6) by displacement reactions of thf from [cis-
Pt(C6F5)2(thf)2]. An X-ray diffraction study confirms that in complex 5b (R ) SiMe3) the
mononuclear rhodium fragment “Cp*Rh(CtCSiMe3)2(PEt3)” acts as a chelating bidentate
ligand toward the alkynyl-bridged diplatinum organometallic unit Pt(µ-1κCR:η2-CtCSiMe)2-
Pt(C6F5)2.
Ch a r t 1
In tr od u ction
The literature is now rich in studies involving the
preparation and chemistry of alkynyl-bridged binuclear
complexes LnM(µ-CtCR)2M′Ln′,1 which are attractive
due to their structural aspects and reactivity. Surpris-
ingly enough, only a few examples of trinuclear com-
plexes with the metal centers doubly bridged by alkynyl
ligands have been reported.2,3 In these molecules the
central metal core [M](1κCR-CtCR)4 ([M] ) M or MLn)
can usually be regarded as a simple bis-chelating ligand
bridging two identical neutral or cationic fragments (A,
Chart 1).2c-e,3a-f Three examples of trinuclear cations
M2M′ (Pt2Ag,3f Ti2Ag,2f Pt2Cu2b) formed by two orthogo-
† Universidad de La Rioja.
‡ Universidad de Zaragoza-Consejo Superior de Investigaciones
Cient´ıficas.
(1) See for example: (a) Lang, H.; Ko¨hler, K.; Blau, S. Coord. Chem.
Rev. 1995, 143, 113. (b) Pavankumar, P. N. V.; J emmis, E. D. J . Am.
Chem. Soc. 1988, 110, 125, and references therein. (c) Ara, I.;
Ferna´ndez, S.; Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T.
Organometallics 1997, 16, 5923. (d) Zhang, D.; McConville, D. B.;
Harbusa, J . M.; Tessier, C. A.; Youngs, W. J . J . Am. Chem. Soc. 1998,
120, 3506. (e) Schottek, J .; Erker, G.; Fro¨chlich, R. Eur. J . Inorg. Chem.
1998, 551. (f) Mihan, S.; Weidmann, T.; Weinrich, V.; Fenske, D.; Beck,
W. J . Organomet. Chem. 1997, 541, 423. (g) Yam, V. W.-W.; Lee, W.-
K.; Cheung, K. K.; Lee, H.-K.; Leung, W.-P. J . Chem. Soc., Chem.
Commun. 1996, 2889. (h) Edwards, A. J .; Paver, M. A.; Raithby, P.
R.; Rennie, M. A.; Russell, C. A.; Wright, D. S. Organometallics 1994,
13, 4967. (i) Olbrich, F.; Behrems, U.; Weiss, E. J . Organomet. Chem.
1994, 472, 365. (j) Cuenca, T. M.; Go´mez, R.; Go´mez-Sal, P.; Rodr´ıgez,
G. M.; Royo, P. Organometallics 1992, 11, 1229. (k) Varga, V.; Mach,
K.; Hiller, J .; Thewalt, U.; Sedmera, P.; Pola´sek, M. Organometallics
1995, 14, 1410. (l) Rosenthal, U.; Pulst, S.; Arndt, P.; Ohff, A.; Tillack,
A.; Baumann, W.; Kempe, R.; Burlakov, V. V. Organometallics 1995,
14, 2961, and references therein.
nal “LnM(CtCR)2” fragments acting as bidentate diyne
ligands toward Cu(I) or Ag(I) (B, Chart 1), and a
trimetallic mixed valence complex [Yb3Cp*4(CtCPh)4],
(2) (a) Boncella, J . M.; Tilley, T. D.; Andersen, R. A. J . Chem. Soc.,
Chem. Commun. 1984, 710. (b) Yamazaki, S.; Deeming, A. J . J . Chem.
Soc., Dalton Trans. 1993, 3051. (c) Edwards, A. J .; Fallaize, A.; Raithby,
P. R.; Rennie, M. A.; Steiner, A.; Verhovevoort, K. L.; Wright, D. S. J .
Chem. Soc., Dalton Trans. 1996, 133. (d) Kawaguchi, H.; Tatsumi, K.
Organometallics 1995, 14, 4294. (e) Zhang, D.; McConville, D. B.;
Tessier, C. A.; Youngs, W. J . Organometallics 1997, 16, 824. (f)
Hayashi, Y.; Osawa, M.; Kobayashi, K.; Sato, T.; Sato, M.; Wakatsuki,
Y. J . Organomet. Chem. 1998, 569, 169.
10.1021/om990753y CCC: $19.00 © 2000 American Chemical Society
Publication on Web 01/27/2000

[Pt(CtCR)4]2- as Double Alkynylation Reagents
Organometallics, Vol. 19, No. 4, 2000 491
Ch a r t 2
containing symmetrically bridging σ-CtCPh ligands (C,
Chart 1),2a have also been reported. The use of [Pt(Ct
CR)4]2- moieties (1, R ) t-Bu a , SiMe3 b, Ph c) as
precursors to homo- and heteroalkynyl-bridged plati-
num complexes has allowed us to isolate a variety of
bi- and trinuclear species, in which the alkynyl entities
of the tetraalkynyl platinate precursor remain σ-bonded
to the platinum center and coordinate to the metal atom
of one [Pd(C3H5)]3d or two [HgX2,3a CoCl2,3b AgL,3c Pd-
(C3H5),3d Rh(COD),3e MX (M ) Ag, Cu; X ) Cl, Br)3c]
units in an η2 fashion. Surprisingly, in similar reactions
with 2 equiv of [cis-Pt(C6F5)2(thf)2], the alkynylplati-
nates act as monoalkynylating agents toward one of the
two “cis-Pt(C6F5)2” units, yielding trimetallic compounds
possessing both a chelating cis-platinate and a σ/π
doubly alkynyl bridged system4 (D, Chart 1).
In this paper we report on the use of the anions
[Pt(CtCR)4]2- (R ) t-Bu, SiMe3, Ph) as double alkyny-
lation reagents. The efficiency of this behavior is
demonstrated in the synthesis of a series of heterobi-
metallic chelating bis(alkyne) derivatives [(PEt3)Cp*M(µ-
CtCR)2Pt(CtCR)2] (M ) Rh, 2; Ir, 3), formed via
migration of two σ-alkynyl groups from Pt to Rh or Ir.
These complexes are the first in which bis(alkynyl)-
platinum substrates are stabilized by η2-alkyne interac-
tions. The use of these binuclear derivatives (2, 3) as
precursors to a series of unusual asymmetric trinuclear
double bis(alkynyl) compounds [(PEt3)Cp*M(µ-CtCR)2-
Pt(µ-CtCR)2Pt(C6F5)2] (M ) Rh, 5a ,b; Ir, 6a -c) and the
X-ray crystal structure determination of 5b are also
presented in this paper.
[Pt(CtCR)4]2- (R ) t-Bu, SiMe3) 1 toward the solvento
species [MCp*(PEt3)(acetone)2]2+ (M ) Rh, Ir) prepared
in situ by treating [MCp*X2(PEt3)] (M ) Rh, X ) Cl; M
) Ir, X ) I) with AgClO4 (2 equiv) in acetone. All efforts
to obtain trinuclear doubly alkynyl bridged M-Pt-M
complexes by addition of 0.5 equiv of [Pt(CtCR)4]2- (R
) t-Bu a , SiMe3 b, Ph c) to solutions of [MCp*(PEt3)-
(acetone)2]2+ (∼1 equiv) were unsuccessful, even at low
temperatures (-30 °C). Probably due to a complex
decomposition reaction (characterized by 31P NMR), only
compounds 2a (M ) Rh and R ) t-Bu) and 3c (M ) Ir
and R ) Ph) were isolated, and in very low yield (∼10%
based in Pt), while in the other cases a mixture of
compounds, which we were not able to identify, was
obtained from the resulting dark solutions. In contrast,
the reactions between [Pt(CtCR)4]2- (R ) t-Bu 1a ,
SiMe3 1b, Ph 1c) and 1 equiv of the dicationic substrate
[MCp*(PEt3)(acetone)2]2+ at low temperature (-20 °C)
(Scheme 1) give the neutral binuclear compounds
[(PEt3)Cp*M(µ-CtCR)2Pt(CtCR)2] (M ) Rh, 2a ,b; Ir,
3), which are isolated in moderate (∼48%, M ) Rh) or
low (M ) Ir, 23% 3a , 28% 3b) yields, except complex 3c
(80% yield) (see Experimental Section for details). The
analogous phenylethynyl derivative 2c could not be
isolated, presumably due to their extremely low stability
in solution, even at low temperatures (-30 °C). The
reaction mixture decomposes within seconds. In fact,
complexes 2a ,b and 3a -c are moderately air-stable as
solids, but they also decompose in solution. Unfortu-
nately, we have not been able to obtain suitable crystals
for an X-ray analysis of any of these derivatives (2, 3).
With the aim of obtaining structural information for one
complex of the same nature as 2 or 3, we prepared the
analogous triphenylphosphine derivative 4b, which was
obtained in low yield (25%) starting from 1b and the
corresponding solvento species [RhCp*(PPh3)(acetone)2]-
(ClO4)2 prepared in situ. Because of poor crystal quality,
the structure analysis is not of high accuracy. Neverthe-
less, the connectivity, shown in Scheme 1, was unequivo-
cally established, confirming the presence of a neutral
“Cp*(PPh3)Rh(CtCSiMe3)2” fragment, which acts as a
chelating diyne ligand toward the fragment “Pt(σ-Ct
CSiMe3)2”. For the triethylphosphine derivatives 2 and
3, their spectroscopic data (similar to those of 4b) and,
indirectly, the molecular structure of 5b support the
chelating formulation drawn in Scheme 1. The mass
spectra confirm their binuclear nature, through the
observation of peaks whose isotopic distributions cor-
respond to those expected for the binuclear fragments,
and also support the double alkynyl migration process
through the presence of peaks assignable to the loss of
the platinum “Pt(CtCR)2” fragment, such as [MCp*-
(PEt3)(CtCt-Bu)2] (m/z 518, 37%, 2a ; 609, 10%, 3a ) or
[MCp*(PEt3)(CtCR)] (m/z 527, 100%, 3a ; 453, 26%, 2b),
Resu lts a n d Discu ssion
We have recently found that when the homoleptic
platinum substrates 1 react with 2 equiv of Rh(I)
solvento species [Rh(COD)S2]+, the platinum centers
retain the σ-coordination to the alkynyl fragments,
providing neutral 1:2 adducts of the type A (Chart 1).5
Despite the presence of electrophilic Rh centers, no
alkynylation processes were observed, indicating that
the Pt center has a greater preference for the electron
density associated with the sp R-carbon of the alkynyl
groups than does Rh(I). Recent studies on binuclear d6-
d8 complexes [(PEt3)Cp*M(µ-CtCR)2M′(C6F5)2] (M )
Rh, Ir; M′ ) Pt, Pd), which exhibit nonplanar structures,
have shown that, in these systems, the metal site
preference for σ-alkynyl coordination (Ir-Pt/Pd and
Rh-Pd, chelating type; Rh-Pt σ/π) follows the order Ir-
(III) > Pt(II) > Rh(III) > Pd(II) (Chart 2).6
As a continuation of these studies, and aiming to
isolate bi- and trinuclear compounds, we have studied
the reactivity of the homoleptic platinum substrates
(3) (a) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno,
M. T. J . Chem. Soc., Dalton Trans. 1994, 3343. (b) Ara, I.; Berenguer,
J . R.; Fornie´s, J .; Lalinde, E. Inorg. Chim. Acta 1997, 264, 199. (c)
Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T. J . Organomet. Chem.
1995, 490, 179. (d) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez,
F. Organometallics 1996, 15, 4537. (e) Ara, I.; Berenguer, J . R.; Fornie´s,
J .; Lalinde, E. Organometallics 1997, 16, 3921. (f) Ara, I.; Berenguer,
J . R.; Fornie´s, J .; Lalinde, E.; Moreno, M. T. J . Organomet. Chem. 1996,
510, 63.
(4) Fornie´s, J .; Lalinde, E.; Mart´ın, A.; Moreno, M. T. J . Chem. Soc.,
Dalton Trans. 1994, 135.
(5) Ara, I.; Berenguer, J . R.; Fornie´s, J .; Lalinde, E. Organometallics
1997, 16, 3921.
(6) Ara, I.; Berenguer, J . R.; Eguiza´bal, E.; Fornie´s, J .; Lalinde, E.;
Mart´ın, A.; Mart´ınez, F. Organometallics 1998, 17, 4578.

492 Organometallics, Vol. 19, No. 4, 2000
Berenguer et al.
Sch em e 1
respectively. The presence of bridging and terminal
alkynyl groups in all complexes is inferred from the IR
data. The ν(CtC) absorptions of the bridging ligands
(1940-2077 cm-1) and, particularly, the ∆ν(CtC)(average)
shift relative to the [MCp*(CtCR)2(PEt3)]6 monomers
(36 cm-1 for 3c to 116 cm-1 for 2a ) are consistent with
a simple complexation of the “Pt(CtCR)2” unit by the
bis(alkynyl) d6 fragment, both formed via a double
intramolecular alkynyl migration from Pt to Rh or Ir.
Larger shifts should be expected for a σ/π type double
alkynyl bridging system resulting from a simple mono-
alkynyl migration.1e,6,7 Moreover, the ν(CtC) bands due
to the terminal alkynyl groups (2015-2127 cm-1) are
significantly shifted to higher frequencies in relation to
the platinum precursors. As has been previously
noted,4,7a,8 this fact can be interpreted as a consequence
of the alkynylation process, which reduces the net
charge on the Pt center. Due to the decrease in electron
density, the Pt atom is a worse π-back donor toward
the remaining CtCR ligands in the resulting neutral
“Pt(CtCR)2” fragment. Actually, the position of these
latter bands is comparable to that observed for bis-
(alkynyl)platinum fragments stabilized by neutral ligands
ligands. In each case, the t-Bu and SiMe3 signals which
appear at lower frequencies [δ 1.17, 2a , 3a (t-Bu); 0.06,
2b; 0.05, 3b; -0.01, 4b (SiMe3)] are assigned to terminal
groups by comparison with the analogous resonance in
1 (δ 1.14, 1a ; 0.02, 1b). The more deshielded resonances
[δ 1.32, 2a ; 1.34, 3a (t-Bu); and 0.22, 2b, 3b; 0.07 4b
(SiMe3)] are tentatively attributed to bridging alkynyl
ligands. Similar spectra (1H and 31P NMR) were ob-
served at low temperature (-50 °C), thus suggesting the
presence of only one isomer or a rapid interconversion
of conformers in solution. In accord with previous
results6,10 and the structural disposition found for the
related triphenylphosphine 4b, the formation of the
conformer with the “Pt(CtCR)2” fragment endo to the
Cp* ligand is suggested (see Scheme 1). This assumption
is also consistent with the relative disposition of the
central platinum atom in the final trinuclear derivative
5b.
The formation of 2 and 3 is remarkable for several
reasons. First, double alkynylation processes are very
rare, and only recently have we reported the first
examples observed by reacting the mixed alkynyl sub-
strates [cis-Pt(C6F5)2(CtCR)2]2- (R ) Ph, SiMe3) with
(e.g., [cis-Pt(CtCt-Bu)2L2], L ) PPh3 2123 cm-1 7a
,
the iridium(III) species [Cp*Ir(PEt3)(acetone)2]+2 6,10
In
.
PPh2H 2118 cm-1;9 [trans-Pt(CtCSiMe3)2(PPh3)2], 2041
cm-1 7b). Although the low stability of 2 and 3 in solution
precludes characterization by 13C NMR spectroscopy,
the corresponding spectrum of 4b was simple and
displays the alkynyl carbon resonances in the usual
range with the expected splitting pattern [bridging CR
this context, it is worth noting that a double alkynyl
migration has also been suggested recently by Chouk-
roun et al. to explain the formation of the coupled
products [Cp2V(µ-η2:η4-butadiyne)MCp′2] (Cp′ ) Cp, M
) Ti, Zr; Cp′ ) C5H4SiMe3, M ) Zr), starting from
[Cp′2M(CtCPh)2] and vanadocene.11
Moreover, we had previously found that replacing Ir
with Rh in the above reaction did not yield the analo-
gous rhodium derivatives; rather binuclear σ/π com-
plexes [(PEt3)Cp*Rh(µ-CtCR)2Pt(C6F5)2] (R ) Ph, SiMe3),
resulting from a single alkynyl migration from [cis-Pt-
(C6F5)2(CtCR)2]2- to [RhCp*(PEt3)(acetone)2]2+, were
isolated. These formally zwitterionic complexes are also
formed starting from neutral [RhCp*(CtCR)2(PEt3)]
and “Pt(C6F5)2” precursors, showing that the Rh center
has, in these species, lesser preference for the σ-coor-
1
2
112.03 (dd, J C-Rh ) 44.8, J C-P ) 26.9), Câ 102.76 (dd,
2J C-Rh ) 7.8, J C-P ) 2.3); terminal CR 104.26 (d, J )
3
2.4), Câ 101.73(s)]. The proton spectra contain, in
addition to signals due to the Cp* and PEt3 ligands,
resonances assigned to bridging and terminal CtCR
(7) (a) Fornie´s, J .; Go´mez-Saso, M. A.; Lalinde, E.; Mart´ınez, F.;
Moreno, M. T. Organometallics 1992, 11, 2873. (b) Berenguer, J . R.;
Fornie´s, J .; Mart´ınez, F.; Cubero, J .; Lalinde, E.; Moreno, M. T.; Welch,
A. J . Polyhedron 1993, 12, 1797. (c) Erker, G. Fro¨mberg, W.; Bern, R.;
Mynott, R.; Angermund, K.; Kru¨ger, C. Organometallics 1989, 8, 911.
(8) (a) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F.;
Urriolabeitia, E.; Welch, A. J . J . Chem. Soc., Dalton Trans. 1994, 1291.
(b) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F. Organome-
tallics 1996, 14, 2532.
(10) Berenguer, J . R.; Fornie´s, J .; Lalinde, E.; Mart´ınez, F. J . Chem.
Soc., Chem. Commun. 1995, 1227.
(9) Falvello, L. R.; Fornie´s, J .; Go´mez, J .; Lalinde, E.; Mart´ın, A.;
Moreno, M. T.; Sacrista´n, J . Chem. Eur. J . 1999, 5, 474.
(11) Danjoy, C.; Zhao, J .; Donnadieu, B.; Legros, J .-P.; Valade, L.;
Choukron, R.; Zwick, A.; Cassoux, P. Chem. Eur. J . 1998, 4, 1100.

[Pt(CtCR)4]2- as Double Alkynylation Reagents
Organometallics, Vol. 19, No. 4, 2000 493
dination than does platinum(II).6 So the formation of
[(PEt3)Cp*Rh(µ-CtCR)2Pt(CtCR)2] (2) is surprising
and reveals the importance of the electron-withdrawing
nature of the C6F5 groups in the stabilization of the σ/π
zwitterionic complexes.
Finally, the synthesis of these complexes confirms the
special ability of bis(alkynyl) metal building blocks to
stabilize unusual organometallic entities, as has been
previously noted.12 As far as we know, these molecules
are the first examples in which the neutral “Pt(σ-Ct
CR)2” unit is stabilized only by η2-acetylene fragments
as coligands. The most closely related compounds are
the mononuclear derivatives [Pt(CtCR)2(COD)].7a,13
Moreover, we have previously observed that, while
[IrCp*(CtCR)2(PEt3)] with R ) Ph or SiMe3 are easily
prepared from [IrCp*X2(PEt3)] using classical metal-
halogen exchange reactions, all attempts to prepare the
tert-butyl analogue (R ) t-Bu) were unsuccessful.6 As
is shown in Scheme 1, the reaction between [Pt(CtCt-
Bu)4]2- and [IrCp*(PEt3)(acetone)2]+2 provides the elu-
sive “IrCp*(CtCt-Bu)2(PEt3)” unit, which seems to be
stabilized in the final dimer 3a .
F igu r e 1. View of the molecular structure of complex 5b,
showing the atom-numbering scheme. Hydrogen atoms
have been omitted for clarity.
bridged trinuclear complex is that in both chelating
systems the dative bonds point in the same direction
(Scheme 1: 5 or 6) in contrast to the usual arrangement
(Chart 1: A or B), which is topologically centric. As
expected, the η2-coordination of both CtCSiMe3 triple
bonds to the neutral platinum atom Pt(1) reduces the
bite angle C(1)-Rh-C(6) to 76.9(5)° (Table 1). This
angle is similar to those observed in related Ir-Pt,Pd
dimers [(PEt3)Cp*Ir(µ-η2-CtCR)2M(C6F5)2] [M/R Pt/Ph
79.9(8)°, Pt/SiMe3 81.0(7)°, Pd/Ph 81.0(7)°]6 and similar
as well to the analogous bite angle at Pt(1) [C(27)-Pt-
(1)-C(32) 78.2(5)°]. Although both platinum atoms have
square-planar geometries, their coordination environ-
ments are different. The stabilization of the platinum
This motion is confirmed by the utility of the bi-
nuclear products as starting materials for higher nucle-
arity compounds. The rather more stable bis(double-
alkynide)-bridged unsymmetrical trinuclear complexes
[(PEt3)Cp*M(µ-CtCR)2Pt(µ-CtCR)2Pt(C6F5)2] (M ) Rh,
5a ,b; Ir, 6) are easily obtained in moderate yields (≈45-
66%) when the organometallic bis(alkyne) “ligands” 2
and 3 are reacted with equimolar amounts of [cis-Pt-
1
(C6F5)2(thf)2]. The H and 31P NMR data of 5 and 6 are
similar to those of the binuclear precursors, confirming
the presence of two inequivalent sets of alkynyl ligands
(1H NMR, see Experimental Section). However, their IR
spectra only exhibit ν(CtC) absorptions in the range
expected for carbon-carbon triple bonds coordinated to
transition metal centers. The 19F NMR spectra of tert-
butyl and trimethylsilyl derivatives 5a ,b and 6a ,b
confirm the presence of “cis-Pt(C6F5)2” fragments with
nonrotating C6F5 groups; a set of five signals (AFMRX
system) reveals the presence of a symmetry plane
containing the three metal centers. Similar spectra were
observed at low temperature, discounting the possibility
of different conformers in solution. Upon increasing the
temperature (up to 40-45 °C) the usual broadening of
the o-F and m-F signals takes place, but coalescence of
the two o-F and two m-F resonances is not reached. By
contrast, the phenyl derivative 6c, as has been previ-
ously observed for related systems,6 seems to be less
rigid in solution. Thus, a similar pattern is observed
only at low temperature. Upon heating, the two halves
of each C6F5 ring average, giving rise to an AA′MXX′
system, probably due to a fast motion of the Pt(C6F5)2
unit above and below of the central platinum coordina-
tion plane (see Experimental Section).
organometallic moiety “cis-Pt(C6F5)2” by acetylenic frag-
ments such as PhCtCPh14 or LnM(CtCR)2
is
1c,6,7a,10
now well established. In this complex the terminal “Pt-
(2)(C6F5)2” unit is symmetrically η2-bonded to the alky-
nyl fragments of the binuclear entity “(PEt3)Cp*Rh(µ-
CtCSiMe3)2Pt(CtCSiMe3)2”, with Pt(2)-C(acetylenic)
distances [2.303(14)-2.364(15) Å] similar to those found
for related derivatives.1c,6,7a The central platinum atom
Pt(1) is σ-bonded to two CR atoms of two alkynyl
bridging ligands and completes its environment by η2-
coordination of the two alkyne groups of the organome-
tallic entity “RhCp*(CtCSiMe3)2(PEt3)”. Despite the
interaction of C(27) and C(32) with Pt(2), the σ Pt(1)-
C(27,32) bond distances are quite short [1.94(2), 1.93-
(2) Å], perhaps reflecting the low trans influence of the
η2-alkyne fragments.7b Significantly, the platinum to
carbon distances within the bis(η2-alkyne)-Pt(1) entity
[2.282(14)-2.39(2) Å] fall into essentially the same
range as the values found in the other chelating bis-
(alkyne) entity, and accordingly, the deviations of all
M-CtC-SiMe3 (M ) Rh, Pt) skeletons from linearity
are rather similar and within the usual range found for
related chelating type (V-shape) {LnM(CtCR)2}M′L′n
systems.1c,3a,6,7a,10
The structure of complex 5b has been established by
an X-ray diffraction study (Figure 1). The most interest-
ing, as well as unprecedented, feature of this alkynyl-
The Pt centers are located out of the best least-
squares plane through the corresponding 3-metalla-1,4-
diyne M(CtC)2 entities (Pt(1), 0.0955 Å; Pt(2), 0.0762
Å). The molecule as a whole has a pseudo-trans arrange-
(12) (a) J anssen, M. D.; Herres, M.; Dedieu, A.; Smeets, W. J . J .;
Spek, A. L.; Grove, D. M.; Lang, H.; van Koten, G. J . Am. Chem. Soc.
1996, 118, 4817. (b) Kova´cs, A.; Frenking, G. Organometallics 1999,
18, 887.
(13) (a) Falvello, L. R.; Ferna´ndez, S.; Fornie´s, J .; Lalinde, E.;
Mart´ınez, F.; Moreno, M. T. Organometallics 1997, 16, 1326. (b) Cross,
R. J .; Davidson, M. F. J . Chem. Soc., Dalton Trans. 1986, 1987.
(14) Uso´n, R.; Fornie´s, J .; Toma´s, M.; Menjo´n, B.; Fortun˜o, C.; Welch,
A. J .; Smith, D. E. J . Chem. Soc., Dalton Trans. 1993, 275.

494 Organometallics, Vol. 19, No. 4, 2000
Ta ble 1. Selected Bon d Len gth s (Å) a n d An gles (d eg) for Com p lex 5b
Berenguer et al.
Pt(1)-C(32)
Pt(1)-C(1)
Pt(2)-C(43)
Pt(2)-C(28)
Rh-C(6)
Rh-C(12)
Rh-C(14)
C(1)-C(2)
C(32)-C(33)
1.93(2)
Pt(1)-C(27)
Pt(1)-C(7)
Pt(2)-C(37)
Pt(2)-C(32)
Rh-C(1)
1.94(2)
2.341(14)
2.03(2)
Pt(1)-C(2)
Pt(1)-C(6)
Pt(2)-C(33)
Pt(2)-C(27)
Rh-C(15)
Rh-C(11)
Rh-*Cent
C(27)-C(28)
Pt(1)‚‚‚(2)
2.282(14)
2.39(2)
2.303(14)
2.364(15)
2.19(2)
2.24(2)
1.878
1.24(2)
3.366(1)
2.322(14)
2.029(14)
2.331(15)
1.96(2)
2.208(13)
2.246(14)
1.19(2)
2.34(2)
2.017(15)
2.239(14)
2.287(3)
1.25(2)
Rh-C(13)
Rh-P
C(6)-C(7)
Rh‚‚‚Pt(1)
1.24(2)
3.297(1)
C(32)-Pt(1)-C(27)
78.2(5)
104.3(5)
108.5(6)
162.5(6)
158.7(6)
85.2(5)
102.3(5)
163.9(5)
164.9(5)
76.9(5)
88.7(4)
127.8
168.4(12)
170.0(13)
165.4(13)
167.1(14)
C(27)-Pt(1)-C(2)
88.5(5)
89.8(6)
164.5(6)
167.4(6)
84.0(6)
C(27)-Pt(1)-C(1)
C(32)-Pt(1)-C(6)
C(32)-Pt(1)-C(1)
C(27)-Pt(1)-C(6)
C(43)-Pt(2)-C(33)
C(43)-Pt(2)-C(32)
C(37)-Pt(2)-C(33)
C(37)-Pt(2)-C(32)
C(6)-Rh-C(1)
C(32)-Pt(1)-C(7)
C(32)-Pt(1)-C(2)
C(27)-Pt(1)-C(7)
C(43)-Pt(2)-C(37)
C(37)-Pt(2)-C(28)
C(37)-Pt(2)-C(27)
C(43)-Pt(2)-C(28)
C(43)-Pt(2)-C(27)
C(6)-Rh-P
87.3(5)
106.9(5)
170.9(5)
156.6(6)
88.2(4)
130.8
127.4
163.5(12)
159.1(13)
147.7(13)
156.6(14)
C(1)-Rh-P
*Cent-Rh-P
*Centa-Rh-C(1)
C(2)-C(1)-Rh
*Cent-Rh-C(6)
C(1)-C(2)-Si(1)
C(6)-C(7)-Si(2)
C(27)-C(28)-Si(3)
C(32)-C(33)-Si(4)
C(7)-C(6)-Rh
C(28)-C(27)-Pt(1)
C(33)-C(32)-Pt(1)
a
*Cent ) centroid of Cp*.
P r ep a r a tion of [(P Et3)Cp *M(µ-1KCr:η2-CtCt-Bu )2P t-
(CtCt-Bu )2] (M ) Rh , 2a; Ir , 3a). 2a. A solution of [RhCp*Cl2-
(PEt3)] (0.15 g, 0.35 mmol) in acetone (20 mL) was treated with
AgClO4 (0.15 g, 0.70 mmol), and the mixture was stirred at
room temperature for 1 h. The AgCl was filtered off, and the
filtrate was cooled at -20 °C and treated with [NBu4]2[Pt(Ct
Ct-Bu)4]‚2H2O (1a ) (0.35 g, 0.32 mmol). The resulting greenish
solution was stirred for 2 min and evaporated to ca. 5 mL,
causing the precipitation of 2a as a yellow solid. Yield: 48.5%.
Anal. Calcd for C40H66PPtRh: C, 54.85; H, 7.59. Found: C,
54.61; H, 7.81. MS(ES-): m/z 876 [M + 1]- 42; 795 [M - C2t-
Bu + 1]- 51; 758 [M - PEt3 + 1]- 63; 740 [M - Cp* + 1]- 17;
715 [M - 2C2t-Bu - 2]- 14; 675 [M - PEt3 - C2t-Bu - 1]-
100; 621 [M - Cp* - PEt3]- 13; 518 [RhCp*(C2t-Bu)2(PEt3)]-
37. IR (cm-1): ν(CtC) 2127(s), 2081(w), 1994(m). 1H NMR
ment of terminal Rh and Pt(2) atoms with respect to
the local Pt(1) coordination plane. The diplatinum “Pt-
(1)(µ-CtCSiMe3)2Pt(2)(C6F5)2” fragment is oriented endo
to the Cp* ring, and the dihedral angle between the
fragment “RhC(1)C(6)” and the central Pt(1) coordina-
tion plane (62.2°) is significantly greater than the
corresponding one between the local Pt(1) and Pt(2)
coordination planes (45.3°). The puckering of both
bimetallacyclic M(CtC)2Pt (M ) Rh, Pt) cores does not
seem to cause any bonding interaction between the
metal centers [Rh‚‚‚Pt(1) 3.297(1) Å, Pt(1)‚‚‚Pt(2) 3.336-
(1) Å].
Exp er im en ta l Section
4
(CDCl3, δ): at 16 °C, 1.93 (d, J P-H ) 2.8, Cp*, 15H); 1.81 (m,
P-CH2-CH3, 6H); 1.32 (s, t-Bu, 18H); 1.17 (s, t-Bu, 18H); 1.05
Gen er a l Com m en ts. All reactions were carried out under
a nitrogen atmosphere. Solvents (hexane, alkane mixture)
were dried by standard procedures and distilled under dry N2
before use, and acetone was treated with KMnO4 and distilled
under dry N2 prior to use. [NBu4]2[Pt(CtCR)4]‚nH2O 1 (n )
2, R ) t-Bu,15 SiMe3;4 n ) 0, R ) Ph15), [MCp*X2(PEt3)] (M )
(m, P-CH2-CH3, 9H). 31P NMR (CDCl3, δ): at 16 °C, 41.23
1
(d, 1J Rh-P ) 135.4). The same patterns for the H and 31P NMR
were observed at -50 °C.
3a . Complex 3a was prepared, as a beige solid, in a similar
way to that for 2a , starting from 0.16 g (0.23 mmol) of [IrCp*I2-
(PEt3)], 0.095 g (0.46 mmol) of AgClO4 (2 h of stirring for the
formation of [IrCp*(PEt3)(acetone)2](ClO4)2), and 0.24 g (0.23
mmol) of 1a . Yield: 23%. Anal. Calcd for C40H66IrPPt: C,
49.77; H, 6.89. Found: C, 49.39; H, 7.18. MS(ES-): m/z 966
[M + 1]- 7; 883 [M - C2t-Bu - 1]- 7; 846 [M - PEt3 - 1]- 11;
803 [M - 2C2t-Bu - 1]- 18; 722 [M - 3C2t-Bu]- 60; 609 [IrCp*-
(C2t-Bu)2(PEt3) + 2]- 10; 527 [IrCp*(C2t-Bu)(PEt3) + 1]- 100;
445 [IrCp*(PEt3) - 2]- 11%. IR (cm-1): ν(CtC) 2126(m), 1998-
Rh, X ) Cl; M ) Ir, X ) I),6 [RhCp*Cl2(PPh3)],16 and AgClO4
were prepared by published methods.
17
NMR spectra were recorded on a Bruker ARX-300 spec-
trometer (all coupling constants are given in Hz). IR spectra
were obtained on Perkin-Elmer 883 or Perkin-Elmer FT-IR
Spectrum 1000 spectrometers using Nujol mulls between
polyethylene sheets. Elemental analyses were carried out with
Perkin-Elmer 2400 CHNS/O or Carlo Erba EA1110 CHNS-O
microanalyzers. Mass spectra were recorded on a VG Autospec
double-focusing mass spectrometer operating in the FAB mode
or an HP-5989B mass spectrometer using the ES technique.
Mass spectra of complexes 6a ,b were obtained using the ES-
(+) technique and AgNO3 as ionizing agent.
1
(w). H NMR (CDCl3, δ): at 16 °C, 2.03 (s br, Cp*, 15H); 1.83
(m, P-CH2-CH3, 6H); 1.34 (s, t-Bu, 18H); 1.17 (s, t-Bu, 18H);
1.00 (m, P-CH2-CH3, 9H). 31P NMR (CDCl3, δ): at 16 °C,
-0.03 (s). The same patterns for the 1H and 31P NMR were
observed at -50 °C.
Sa fety Note. Perchlorate salts are potentially explosive.
Only small amounts of material should be prepared, and these
should be handled with great caution.
P r ep a r a tion of [(P Et3)Cp *M(µ-1KCr:η2-CtCSiMe3)2P t-
(CtCSiMe3)2] (M ) Rh , 2b; Ir , 3b). 2b. [NBu4]2[Pt(Ct
CSiMe3)4]‚2H2O (1b) (0.34 g, 0.31 mmol) was added to a filtered
solution of [RhCp*(PEt3)(acetone)2](ClO4)2 (0.32 mmol) in 5 mL
of acetone at -20 °C, prepared from 0.135 g (0.316 mmol) of
[RhCp*Cl2(PEt3)] and 0.13 g (0.63 mmol) of AgClO4. Im-
mediately, the resulting brown suspension was evaporated to
dryness, and the residue was treated with 30 mL of toluene
and filtered. Evaporation of the filtrate to dryness and treat-
(15) Espinet, P.; Fornie´s, J .; Mart´ınez, F.; Toma´s, M.; Lalinde, E.;
Moreno, M. T.; Ruiz, A.; Welch A. J . J . Chem. Soc., Dalton Trans. 1990,
791.
(16) Kang, J . W.; Moseley, K.; Maitlis, P. M. J . Am. Chem. Soc. 1969,
91, 5970.
(17) Smith, G. F.; Ring, F. J . Am. Chem. Soc. 1937, 59, 1889.

[Pt(CtCR)4]2- as Double Alkynylation Reagents
Organometallics, Vol. 19, No. 4, 2000 495
ment of the residue with cold Et2O (≈5 mL) yielded complex
(10 mL) was added [cis-Pt(C6F5)2(thf)2] (0.071 g, 0.11 mmol).
The resulting garnet solution was stirred for 5 min and
evaporated to dryness. Treatment of the residue with cold Et2O
(≈5 mL) afforded complex 5a as a yellow solid. Yield: 64.4%.
Anal. Calcd for C52F10H66PPt2Rh: C, 44.45; H, 4.73. Found:
C, 44.41; H, 4.95. MS(FAB+): m/z 1404 [M]+ 2; 758 [2a - PEt3
+ 1]+ 61; 677 [2a - PEt3 - C2t-Bu + 1]+ 11; 437 [RhCp*(C2t-
Bu)(PEt3)]+ 25; 356 [RhCp*(PEt3)]+ 59. IR (cm-1): ν(CtC)
2b as a pale brown solid. Yield: 48.5%. Anal. Calcd for C36H66
-
PPtRhSi4: C, 45.98; H, 7.07. Found: C, 45.75; H, 6.82. MS-
(FAB+): m/z 939 [M]+ 10; 745 [(PEt3)Cp*Rh(C2SiMe3)2Pt]+ 26;
648 [(PEt3)Cp*Rh(C2SiMe3)Pt]+ 57; 453 [RhCp*(C2SiMe3)-
(PEt3)]+ 26; 356 [RhCp*(PEt3)]+ 94. IR (cm-1): ν(CtC) 2056-
1
(vs), 2037(vs), 1951(vs), 1943(vs). H NMR (CDCl3, δ): at 16
°C, 1.95 (s br, Cp* 15H); 1.81 (m, P-CH2-CH3, 6H); 1.05 (m,
P-CH2-CH3, 9H); 0.22 (s, SiMe3, 18H); 0.06 (s, SiMe3, 18H).
1
1997(s); ν(C6F5)x-sensitive 799(vs), 786(vs). H NMR (CDCl3, δ):
1
31P NMR (CDCl3, δ): at 16 °C, 40.18 (d, J Rh-P ) 131.3). The
at 16 °C, 1.95 (d, 4J P-H ) 2.6 Hz, Cp*, 15H); 1.87 (m, P-CH2-
CH3, 6H); 1.32 (s, t-Bu, 18H); 1.11 (m, P-CH2-CH3, 9H); 1.08
(s, t-Bu, 18H). 19F NMR (CDCl3, δ): at 16 °C, -113.31 (dm, 2
o-F), -114.04 (m, 2 o-F) (195Pt satellites are barely observed
due to its low solubility); -164.81 (t, 2 p-F); -165.85 (m, 2
m-F); -166.20 (m, 2 m-F). 31P NMR (CDCl3, δ): at 16 °C, 39.79
1
same patterns were observed for the H and 31P NMR at -50
°C.
3b. Complex 3b was prepared, as a beige solid, by following
the synthesis described for 2b, but starting from 0.20 g (0.29
mmol) of [IrCp*I2(PEt3)], 0.12 g (0.57 mmol) of AgClO4, and
0.30 g (0.27 mmol) of 1b and treating the final residue with
1
1
(d, J Rh-P ) 130.8). Similar spectra were observed for the H,
19F, and 31P NMR at -50 °C.
cold hexane (≈5 mL). Yield: 28%. Anal. Calcd for C36H66
-
5b. Complex 5b was prepared as a yellow solid using a
method similar to that described for 5a and starting from 0.12
g (0.13 mmol) of 2b and 0.086 g (0.13 mmol) of cis-[Pt(C6F5)2-
(thf)2]. Yield: 54.5%. Anal. Calcd for C48F10H66PPt2RhSi4: C,
39.24; H, 4.43. Found: C, 38.93; H, 4.49. MS(ES-): m/z 1351
[M - PEt3 + 1]- 80; 1334 [M - Cp* + 1]- 52; 1227 [M - PEt3
- SiMe3]- 35; 1183 [M - PEt3 - C6F5]- 14; 1143 [M - Cp* -
SiMe3 - PEt3 + 1]- 52; 973 [M - Cp* - C6F5 - SiMe3 - PEt3
- 2]- 28. IR (cm-1): ν(CtC) 1952(vs), 1937(vs), 1928(vs);
IrPPtSi4: C, 42.00; H, 6.46. Found: C, 42.19; H, 6.46. MS-
(ES+): m/z 1029 [M]+ 11; 957 [M - SiMe3 + 1]+ 100. IR (cm-1):
ν(CtC) 2054(vs), 2036(vs), 1954(vs), 1940(vs). 1H NMR
4
(CDCl3, δ): at 16 °C, 2.05 (d, J P-H )1.7, Cp*, 15H); 1.84 (m,
P-CH2-CH3, 6H); 1.00 (m, P-CH2-CH3, 9H); 0.22 (s, SiMe3,
18H); 0.05 (s, SiMe3, 18H). 31P NMR (CDCl3, δ): at 16 °C,
-0.96 (s).
P r ep a r a tion of [(P Et3)Cp *Ir (µ-1KCr:η2-CtCP h )2P t(Ct
CP h )2], 3c. The addition of [NBu4]2[Pt(CtCPh)4] (1c) (0.18 g,
0.17 mmol) to a filtered solution of [IrCp*(PEt3)(acetone)2]-
(ClO4)2 (0.17 mmol) in 5 mL of acetone at -20 °C, prepared
from 0.12 g (0.17 mmol) of [IrCp*Cl2(PEt3)] and 0.07 g (0.34
mmol) of AgClO4, caused the immediate precipitation of
complex 3c as a beige solid, which was filtered and washed
1
ν(C6F5)x-sensitive 802(vs), 792(s). H NMR (CDCl3, δ): at 16 °C,
4
1.95 (d, J P-H ) 2.7, Cp*, 15H); 1.85 (m, P-CH2-CH3, 6H);
1.10 (m, P-CH2-CH3, 9H); 0.21 (s, SiMe3, 18H); -0.02 (s,
SiMe3, 18H). 19F NMR (CDCl3, δ): at 16 °C, -114.11 (m,
3
3J Pt-o-F ) 432, 2 o-F); -114.36 (d, J Pt-o-F ) 445, 2 o-F);
-165.05 (t, 2 p-F); -166.18 (m, 2 m-F); -166.63 (m, 2 m-F).
31P NMR (CDCl3, δ): at 16 °C, 40.16 (d, 1J Rh-P ) 129.4). Similar
spectra were observed for the 1H, 19F, and 31P NMR at low
temperature (-50 °C). In the 19F NMR spectra, although only
a broad signal is observed at 45 °C for both the o-F and the
m-F, the Tc has still not been reached.
6. Complexes 6 were prepared as white (6a ), beige (6b), or
brown (6c) solids in a way similar to that described for 5a ,
but treating the final residue with cold EtOH (≈5 mL). [6a :
0.11 g (0.11 mmol) of 3a and 0.077 g (0.11 mmol) of [cis-Pt-
(C6F5)2(thf)2]. Yield: 51%. 6b: 0.044 g (0.043 mmol) of 3b and
0.029 g (0.043 mmol) of [cis-Pt(C6F5)2(thf)2]. Yield: 45%. 6c:
0.12 g (0.11 mmol) of 3c and 0.077 g (0.11 mmol) of [cis-Pt-
(C6F5)2(thf)2]. Yield: 66%.]
with cold acetone (≈5 mL). Yield: 84%. Anal. Calcd for C48H50
-
PPtIr: C, 55.16; H, 4.82. Found: C, 55.14; H, 4.91. MS(ES+):
m/z 1046 [M + 1]+ 3. IR (cm-1): ν(CtC) 2108 (m), 2077(vs).
1H NMR (CDCl3, δ): at 16 °C, 7.83, 7.22, 6.96 (m, Ph, 20H);
2.20 (d, 4J P-H )1.5, Cp*, 15H); 1.82 (m, P-CH2-CH3, 6H); 1.03
(m, P-CH2-CH3, 9H). 31P NMR (CDCl3, δ): at 16 °C, 1.98 (s).
1
The same patterns were observed for the H and 31P NMR at
-50 °C.
P r epa r a tion of [(P P h 3)Cp*Rh (µ-1KCr:η2-CtCSiMe3)2P t-
(CtCSiMe3)2], 4b . A filtered solution of [RhCp*(PPh3)-
(acetone)2](ClO4)2 (0.30 mmol) in 10 mL of acetone at -20 °C
[prepared from 0.17 g (0.30 mmol) of [RhCp*Cl2(PPh3)] and
0.12 g (0.30 mmol) of AgClO4 with 1 h of stirring] was treated
with 0.31 g (0.27 mmol) of 1b. Immediately, the resulting
brown solution was evaporated to dryness and the residue
treated with cold EtOH (≈5 mL), yielding complex 4b as a
yellow solid. Yield: 25%. Anal. Calcd for C48H66PPtRhSi4: C,
53.17; H, 6.13. Found: C, 53.35; H, 6.56. MS(ES+): m/z 1084
[M + 1]+ 19; 1013 [M - SiMe3 + 2]+ 88; 985 [M - C2SiMe3 -
2]+ 17; 890 [M - 2C2SiMe3]+ 42; 822 [M - PPh3]+ 29; 597
[RhCp*(C2SiMe3)(PPh3)]+ 20; 499 [RhCp*(PPh3) - 1]+ 17. IR
Da ta for 6a . Anal. Calcd for C52F10H66IrPPt2: C, 41.79; H,
4.45. Found: C, 41.86; H, 4.58. MS(ES+): m/z 1603 [M + Ag
+ 1]+ 25; 1073 [3a + Ag]+ 42; 715 [IrCp*(C2t-Bu)2(PEt3) + Ag]+
100. IR (cm-1): ν(CtC) 1996(w); ν(C6F5)x-sensitive 798(m), 786-
1
4
(m). H NMR (CDCl3, δ): at 16 °C, 2.05 (d, J P-H ) 1.6, Cp*,
15H); 1.89 (m, P-CH2-CH3, 6H); 1.33 (s, t-Bu, 18H); 1.07 (s
br, t-Bu and P-CH2-CH3, 27H). 19F NMR (CDCl3, δ): at 16
°C, -113.37 (dm, 2 o-F), -114.04 (m, 2 o-F) (195Pt satellites
are barely observed due to low solubility); -164.83 (t, 2 p-F);
-165.91 (m, 2 m-F); -166.60 (m, 2 m-F). 31P NMR (CDCl3, δ):
1
(cm-1): ν(CtC) 2063(vs), 2044(vs), 1955(s), 1948(s). H NMR
4
(CDCl3, δ): at 16 °C, 7.56, 7.36 (m, PPh3, 15H); 1.63 (d, J P-H
) 3.4, Cp*, 15H); 0.08 (s, SiMe3, 18H); -0.02 (s, SiMe3, 18H).
1
2
13C NMR (CDCl3, δ): at 16 °C, 134.07 (d, J C-P ) 10.4, o-C,
at 16 °C, -0.15 (s). Similar spectra were observed for the H,
19F, and 31P NMR at low (-50 °C) and high (40 °C) tempera-
tures.
4
PPh3); 130.21 (d, J C-P ) 1.9, p-C, PPh3; this signal overlaps
with one of the signals of the doublet due to the i-C (PPh3),
3
which is centered at δ ∼130); 127.83 (d, J C-P ) 10.4, m-C,
Da ta for 6b. Anal. Calcd for C48F10H66IrPPt2Si4: C, 36.99;
H, 4.27. Found: C, 36.89; H, 4.47. MS(ES+): m/z 1666 [M +
Ag]+ 51; 1139 [3b + Ag + 2]+ 100; 957 [3b + SiMe3 + 1]+ 29.
1
2
PPh3); 112.03 (dd, J C-Rh ) 44.8, J C-P ) 26.9, CR, RhCt
CSiMe3); 104.26 (d, J ) 2.4, CR, PtCtCSiMe3); 103.50 (dd,
1J C-Rh ) 4.2, 2J C-P ) 2.5, C5Me5); 102.76 (dd, 2J C-Rh ) 7.8, 3J C-P
) 2.3, Câ, RhCtCSiMe3); 101.73 (s, Câ, PtCtCSiMe3); 9.47 (dd,
IR (cm-1): ν(CtC) 1951(vs), 1927(vs); ν(C6F5)x-sensitive ) 802-
4
(vs), 791(s). 1H NMR (CDCl3, δ): at 16 °C, 2.05 (d, J P-H
)
3
2J C-Rh ) 2.3, J C-P ) 1.6, C5(CH3)5); 1.11 (s, SiMe3); 0.94 (s,
1.5, Cp*, 15H); 1.88 (m, P-CH2-CH3, 6H); 1.05 (m, P-CH2-
SiMe3). 31P NMR (CDCl3, δ): at 16 °C, 41.91 (d, 1J Rh-P ) 138.6).
The same patterns for the 1H, 13C, and 31P NMR were observed
at -50 °C.
CH3, 9H), 0.22 (s, SiMe3, 18H); -0.03 (s, SiMe3, 18H). 19F NMR
3
(CDCl3, δ): at 16 °C, -114.13 (m, J Pt-o-F ≈ 425, 2 o-F);
-114.36 (dm, 3J Pt-o-F ≈ 435, 2 o-F); -165.11 (t, 2 p-F); -166.34
(m, 2 m-F); -166.60 (m, 2 m-F). 31P NMR (CDCl3, δ): at 16
°C, -0.46 (s). Similar 1H, 19F, and 31P NMR spectra were
observed at low (-50 °C) and high (40 °C) temperatures.
Da ta for 6c. Anal. Calcd for C60F10H50IrPPt2: C, 45.77; H,
P r ep a r a t ion of [(P E t 3)Cp *M(µ-1KCr:η2-CtCR )2P t (µ-
2KCr:η2-CtCR)2P t(C6F 5)2] (M ) Rh ; R ) t-Bu 5a , SiMe3
5b; M ) Ir ; R ) t-Bu 6a , SiMe3 6b, R ) P h 6c). 5a . To a
cooled (-20 °C) solution of 2a (0.092 g, 0.11 mmol) in CH2Cl2

496 Organometallics, Vol. 19, No. 4, 2000
Berenguer et al.
Ta ble 2. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 5b
3.20. Found: C, 45.83; H, 3.60. MS(ES-): No molecular peak
was observed, m/z 563 [Pt(C2Ph)2(C6F5)]- 100. IR (cm-1): ν-
(CtC) 2018(w), 1967(w br); ν(C6F5)x-sensitive ) 803(vs br). 1H
NMR (CDCl3, δ): at 16 °C, 7.80, 7.25, 7.07, 6.96, 6.79 (m, Ph,
20 H); 2.17 (s, Cp*, 15H); 1.86 (m, P-CH2-CH3, 6H); 1.03 (m,
P-CH2-CH3, 9H). 19F NMR (CDCl3, δ): at 16 °C, -116.49 (d,
3J Pt-o-F ≈ 373, 4 o-F); -164.89 (t, 2 p-F); -166.49 (m, 4 m-F).
The same pattern is observed at 40 °C, but on cooling the o-F
signal broadens and splits into two different signals (at -5
°C, δ -116.45, -116.64), from which the lower frequency one
continues to broaden at lower temperatures (-50 °C, δ
-116.28, ca. -117).31P NMR (CDCl3, δ): at 16 °C, 2.21 (s).
empirical formula
fw
C48H66F10PPt2RhSi4
1469.46
unit cell dimens
a (Å)
27.588(2)
b (Å)
10.4447(9)
c (Å)
20.230(2)
5829.4(8), 4
0.71073
volume (Å3), Z
wavelength (Å)
temperature (K)
radiation
293(1)
graphite-monochromated Mo KR
orthorhombic
Pca21
cryst syst
1
Similar spectra were observed for the H and 31P NMR at low
space group
abs coeff (mm-1
)
5.239
(-50 °C) and high (40 °C) temperatures.
transmission factors
abs corr
diffractometer
0.968, 0.607
Ψ scans
Enraf-Nonius CAD4
X-r a y Cr ysta l Str u ctu r e Deter m in a tion . Suitable crys-
tals of 5b were obtained by slow diffusion of n-hexane into
CH2Cl2 solutions of the complex at -30 °C.
2θ range for data collectn (deg) 4-50 (+h, +k, +l)
Crystal data and other details of the structure analysis are
presented in Table 2. The selected crystal was glued to a glass
fiber. Unit cell constants were determined from 25 accurately
centered reflections with 21.9° < 2θ < 31.5°. Data were
collected using ω-scans. Three check reflections remeasured
after every 3 h showed a decay of ca. 13% of the diffracted
intensities over the period of data collection. The space group
Pca21 is established (and Pbcm is ruled out) by the fact that Z
) 4, together with the absence of inversion or 2-fold rotation
symmetry in the molecule, and the orientation of the molecular
pseudo-symmetry plane, which is not parallel to any of the
faces of the orthorhombic cell. In space group Pbcm with Z )
4, the molecule would have to lie on either an inversion center,
a 2-fold axis, or a crystallographic mirror. The positions of the
heavy atoms were determined from the Patterson map. The
remaining atoms were located in successive difference Fourier
syntheses. H atoms were added at calculated positions (C-H
) 0.96 Å), with isotropic displacement parameters assigned
as 1.2 times the equivalent isotropic U’s of the corresponding
C atoms for CH2 hydrogens, and 1.5 times for CH3 hydrogens.
A final difference electron density map showed no peaks above
1 e Å-3 (max 0.94; largest diff hole -0.91). The refinement was
carried out using the program SHELXL-93.18
no. of reflns collected
no. of ind reflns
5241
5241
refinement method
goodness-of-fit on F2 b
final R indices (I > 2σ(I))a
R indices (all data)
abs structure param
full-matrix least-squares on F2
1.038
R1 ) 0.0356, wR2 ) 0.0805
R1 ) 0.0598, wR2 ) 0.0912
0.005(7)
R1 ) ∑(|Fo| - |Fc|)/∑|Fo|; wR2 ) [∑w(Fo - Fc )2/∑w(Fc2)2 ]1/2
.
a
2
2
Goodness-of-fit ) [∑w(Fo - Fc2)2/(nobs - nparam)]1/2. w ) [σ2(Fo)
b
2
+ (g1P)2 + g2P]-1; P ) [max(Fo2; 0) + 2Fc2]/3.
PB 98-1595-CO2-01,02 and PB98-1593) and the Uni-
versidad de La Rioja (Project API-99/B16) for their
financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables giving posi-
tional and thermal parameters, bond distances, and bond
angles for 5b. Basic crystallographic data table for 4b. View
of the molecular structure of complex 5b, showing full el-
lipsoids for all the atoms at their 50% probability level. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM990753Y
Ack n ow led gm en t. We thank the Direccio´n General
de Ensen˜anza Superior e Investigacio´n (Spain, Project
(18) Sheldrick, G. M. SHELXL-93, a program for crystal structure
refinement; University of Go¨ttingen: Germany, 1993.