Stabilized bis-ylides as a source of carbene ligands in palladium(II) and platinum(II) complexes

Article abstract of DOI:10.1021/om020467d

The reaction of the α-stabilized bis-ylide [Ph₃P=C(CO₂Me)-C(CO₂Me)-PPh₃] with M(II) bis-solvato derivatives, cis-[M(C₃F₅)₂(OC₄H₈) ₂] or [M(C∧X)(OC₄H₈)₂]ClO₄ (M = Pd, Pt; C∧X= orthometalated ligand), yields the ylide-carbene complexes cis-[M(C₆F₅)₂{C(CO₂Me)-C(CO₂ Me)(PPh₃)}(PPh₃)] (M = Pt 1a, Pd 1b) or [M(C∧X){C(CO₂Me)-C(CO₂Me)(PPh₃)}(PPh₃ )]-ClO₄ (M = Pt, C∧X = o-CH₂C₆H₄P(o-tolyl)₂, 2; M = Pd, C∧X = o-CH₂C₆H₄P(o-tolyl)₂, 3; CH₂C₉H₆N-C⁸,N, 4; NC₅H₄-o-C₆H₄, 5; C₁₃H₈N, 6). The reaction appears to proceed with P=C bond cleavage, generating a carbene-ylide ligand [:C(CO₂Me)-C(CO₂Me)PPh₃] and a PPh₃ group, both coordinated to the metal center. The reaction of the solvato complexes [M(C∧X)(OC₄H₈)(PPh₃)]ClO₄ with the bis-ylide results in the selective formation of [M(C∧X)-(PPh₃)₂]ClO₄ (M = Pt, C∧X = o-CH₂C₆H₄P(o-tolyl)₂, 7; M = Pd, C∧X = CH₂C₉H₆N-C⁸,N, 8), showing that when one vacant position is available, only the PPh₃ group binds to the metal center, and the carbene fragment decomposes to O=PPh₃ and dimethylfumarate. On the other hand, the reaction of the bis-solvato precursors [Pd(C₆F₅)(L)(OC₄H₈)₂]ClO ₄ with the bis-ylide yields the corresponding metallacyclopropane [Pd{trans-C(C₆F₅)(CO₂Me)-C(PPh₃-(CO ₂Me)}(L)(PPh₃)](ClO₄) (L = SC₄H₈, 9; PPh₃,10), probably through the initial formation of an ylide-carbene complex-similar to 1-6-followed by the migratory insertion of the carbene ligand into the Pd-C(C₆F₅) bond and coordination of the newly generated ylide function. The crystal structure of complex 1a·CH₂Cl₂ has been analyzed by X-ray diffraction.

Full text of DOI:10.1021/om020467d

1132
Organometallics 2003, 22, 1132-1144
Sta bilized Bis-ylid es a s a Sou r ce of Ca r ben e Liga n d s in
P a lla d iu m (II) a n d P la tin u m (II) Com p lexes
Larry R. Falvello,† Rosa Llusar,‡ Marina E. Margalejo,† Rafael Navarro,*,† and
Esteban P. Urriolabeitia*,†
Departamento de Quı´mica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cientı´ficas,
E-50009 Zaragoza, Spain, and Departament de Ciencies Experimentals,
Campus Riu Sec, Universitat J aume I, POB 224, E-12071 Castello´, Spain
Received J une 13, 2002
The reaction of the R-stabilized bis-ylide [Ph3PdC(CO2Me)-C(CO2Me)dPPh3] with M(II)
bis-solvato derivatives, cis-[M(C6F5)2(OC4H8)2] or [M(C∧X)(OC4H8)2]ClO4 (M ) Pd, Pt; C∧X
) orthometalated ligand), yields the ylide-carbene complexes cis-[M(C6F5)2{C(CO2Me)-
C(CO2Me)(PPh3)}(PPh3)] (M ) Pt 1a , Pd 1b) or [M(C∧X){C(CO2Me)-C(CO2Me)(PPh3)}(PPh3)]-
ClO4 (M ) Pt, C∧X ) o-CH2C6H4P(o-tolyl)2, 2; M ) Pd, C∧X ) o-CH2C6H4P(o-tolyl)2, 3;
CH2C9H6N-C8,N, 4; NC5H4-o-C6H4, 5; C13H8N, 6). The reaction appears to proceed with
PdC bond cleavage, generating a carbene-ylide ligand [:C(CO2Me)-C(CO2Me)PPh3] and a
PPh3 group, both coordinated to the metal center. The reaction of the solvato complexes
[M(C∧X)(OC4H8)(PPh3)]ClO4 with the bis-ylide results in the selective formation of [M(C∧X)-
(PPh3)2]ClO4 (M ) Pt, C∧X ) o-CH2C6H4P(o-tolyl)2, 7; M ) Pd, C∧X ) CH2C9H6N-C8,N, 8),
showing that when one vacant position is available, only the PPh3 group binds to the metal
center, and the carbene fragment decomposes to OdPPh3 and dimethylfumarate. On the
other hand, the reaction of the bis-solvato precursors [Pd(C6F5)(L)(OC4H8)2]ClO4 with the
bis-ylide yields the corresponding metallacyclopropane [Pd{trans-C(C6F5)(CO2Me)-C(PPh3)-
(CO2Me)}(L)(PPh3)](ClO4) (L ) SC4H8, 9; PPh3, 10), probably through the initial formation
of an ylide-carbene complexssimilar to 1-6sfollowed by the migratory insertion of the
carbene ligand into the Pd-C(C6F5) bond and coordination of the newly generated ylide
function. The crystal structure of complex 1a ‚CH2Cl2 has been analyzed by X-ray diffraction.
In tr od u ction
Me)-C(CO2Me)dPPh3 (see Figure 1), in which the two
ylidic carbons are adjacent to each other and each one
is stabilized through the presence of a carbonyl oxygen.
This bis-ylide is a yellow solid, stable for short periods
of time when exposed to oxygen or moisture, and easily
prepared in multigram quantities by reaction of di-
methylacetylenedicarboxylate with an excess of PPh3 in
dry Et2O.7 Extensive work has been done on the
synthesis of this bis-ylide and related compounds,8 but
only from a purely synthetic organic point of view, and
no reports have appeared concerning its coordinating
properties toward transition metals.
However, the reactivity of this ligand toward Pd(II)
and Pt(II) substrates has been unexpectedly extensive
and interesting, to the point that we have found at least
four different reactivity patterns, as a function of the
starting material, all of them sharing an initial PdC
bond cleavage in one of the ylide groups, resulting in
the generation of two fragments: a PPh3 ligand and the
ylide carbene :C(CO2Me)-C(CO2Me)dPPh3. Although
the P-C bond activation process is already known, most
of the available data relate to P-C bond activation in
PPhn fragments, giving rise to Ph and PPhn-1 units.9
One of the most striking examples of this type of
In the course of our ongoing research on the coordina-
tion chemistry of stabilized bis-ylide ligands, we have
developed synthetic strategies through which, starting
from bis-phosphonium salts [Ph3PCH2C(O)CH2PPh3]2+
or ylide-phosphonium salts [Ph3PdCHC(O)CH2PPh3]+,
it has been possible to obtain C,C-bonded bis-ylides,1
to promote C-H bond activations2-5 and also to syn-
thesize different types of homo- and heteropolynuclear
systems.6 The versatility shown by this type of system
has prompted us to expand our present studies on the
coordinating properties of phosphorus ylides to other,
related bis-ylide ligands, and we have now focused our
attention on the doubly stabilized bis-ylide Ph3PdC(CO2-
* Corresponding author. E-mail: (R.N.) rafanava@posta.unizar.es;
(E.P.U.) esteban@posta.unizar.es.
† Universidad de Zaragoza-Consejo Superior de Investigaciones
Cient´ıficas.
‡ Universitat J aume I.
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beitia, E. P. Inorg. Chem. 1998, 37, 6007.
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beitia, E. P. Organometallics 1998, 17, 5887.
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R.; Urriolabeitia, E. P. Organometallics 2001, 20, 1424.
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10.1021/om020467d CCC: $25.00 © 2003 American Chemical Society
Publication on Web 02/05/2003

Stabilized Bis-ylides
Organometallics, Vol. 22, No. 5, 2003 1133
F igu r e 1. Resonance forms for the bis-ylide.
activation is the synthesis of phenyl derivatives of
Ni(II) with phosphino-enolate ligands from the reaction
of Ni0(COD)2 (COD ) 1,5-cyclooctadiene) with the
stabilized ylide Ph3PdC(H)C(O)Ph.10,11 The reactivity
that we report here is formally different, since the bis-
ylide behaves as a genuine carbene transfer agent in
the synthesis of complexes with ylide-carbene ligands.
The synthesis of complexes with ylide-carbene ligands
is reported in the literature, but following different
routes: (i) the reaction between metal carbonyls and
strong nucleophilic ylides;12 (ii) phosphine-alkyne cou-
plings promoted by transition metals,13 sometimes
described as alkyne insertions into the metal-phospho-
rus bond; and (iii) intramolecular nucleophilic attack of
nonstabilized ylides to coordinated nitriles.14 On the
other hand, there are very few examples reported in
which an ylide acts as a genuine carbene transfer agent,
and in these cases, a nonstabilized ylide is involved.15
In this contribution we report the use of stabilized
bis-ylides as carbene transfer reagents in the synthesis
of ylide-carbene complexes and, in some cases, their
further reactivity.
Resu lts a n d Discu ssion
1. Syn th esis of Ylid e-Ca r ben e Com p lexes. The
reaction of the bis-solvato derivative [Pt(C6F5)2(THF)2]
with the bis-ylide Ph3PdC(CO2Me)-C(CO2Me)dPPh3
(1:1 molar ratio, THF, rt 30 min) gives, after solvent
evaporation and Et2O addition, the ylide-carbene com-
plex cis-[Pt(C6F5)2{C(CO2Me)-C(PPh3)(CO2Me)}(PPh3)],
1a , as a white solid, stable to air and moisture at
room temperature. In a similar process, [Pd(C6F5)2-
(THF)2] reacts with the bis-ylide, under the same experi-
mental conditions, affording cis-[Pd(C6F5)2{C(CO2Me)-
C(PPh3)(CO2Me)}(PPh3)], 1b (eq 1). Both complexes
(8) (a) Shaw, M. A.; Ward, R. S. In Topics in Phosphorus Chemistry;
Griffith, E. J ., Grayson, M., Eds.; Interscience Publishers: J ohn Wiley
and Sons: New York, 1972; Vol. 7, pp 1-32. (b) J ohnson, A. W.; Tebby,
J . C. J . Chem. Soc. 1961, 2126. (c) Allen, D.; Tebby, J . C.; Williams, D.
H. Tetrahedron Lett. 1965, 28, 2361. (d) Shaw, M. A.; Tebby, J . C.;
Ronayne, J .; Williams, D. H. J . Chem. Soc. (C) 1967, 944. (e) Shaw,
M. A.; Tebby, J . C.; Ward, R. S.; Williams, D. H. J . Chem. Soc. (C)
1968, 1609. (f) Shaw, M. A.; Tebby, J . C.; Ward, R. S.; Williams, D. H.
J . Chem. Soc. (C) 1968, 2795. (g) Waite, N. E.; Tebby, J . C.; Ward, R.
S.; Williams, D. H. J . Chem. Soc. (C) 1969, 1100. (h) Richards, E. M.;
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E.; Tebby, J . C. J . Chem Soc. (C) 1970, 386. (k) Shaw, M. A.; Tebby, J .
C.; Ward, R. S.; Williams, D. H. J . Chem. Soc. (C) 1970, 504. (l)
Richards, E. M.; Tebby, J . C. J . Chem. Soc. (C) 1971, 1059. (m)
Richards, E. M.; Tebby, J . C. J . Chem. Soc. (C) 1971, 1064. (n) Waite,
N. E.; Tebby, J . C.; Ward, R. S.; Shaw, M. A.; Williams, D. H. J . Chem.
Soc. (C) 1971, 1620. (o) Wilson, I. F.; Tebby, J . C. J . Chem. Soc., Perkin
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8864. (c) de la Torre, G.; Gouloumis, A.; Va´zquez, P.; Torres, T. Angew.
Chem., Int. Ed. 2001, 40, 2895. (d) Kwong, F. K.; Chan, K. S.
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V.; Ardura, D.; Garc´ıa-Granda, S. Eur. J . Inorg. Chem. 2000, 499. (g)
Bandini, A. L.; Banditelli, G.; Minghetti, G. J . Organomet. Chem. 2000,
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show correct elemental analyses and mass spectra,
suggesting the incorporation of one bis-ylide unit for
each [M(C6F5)2] fragment. Complex 1a crystallizes as
colorless block-shape crystals, adequate for X-ray pur-
poses, by slow diffusion of Et2O vapor into a CH2Cl2
solution of the crude complex.
X-ray analysis of 1a ‚CH2Cl2 (monoclinic, space group
P21/c) reveals the presence of two independent molecules
in the asymmetric unit. A drawing of one of the two
molecules is presented in Figure 2. Relevant crystal-
lographic parameters concerning the data acquisition
and structure solution and refinement are given in
Table 1 and in the Experimental Section, and selected
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1134 Organometallics, Vol. 22, No. 5, 2003
Falvello et al.
Ta ble 2. Selected Bon d Len gth s (Å) a n d An gles
(d eg) for 1a ‚CH2Cl2
molecule A
2.056(5)
2.076(5)
2.079(5)
2.3019(14)
1.319(6)
1.810(5)
1.200(6)
1.333(6)
1.197(6)
1.489(7)
1.339(6)
1.490(7)
85.78(18)
87.44(19)
96.07(14)
91.25(15)
123.9(5)
121.6(5)
114.5(4)
123.3(4)
125.8(4)
110.0(3)
119.6(4)
128.3(4)
110.5(3)
124.6(5)
123.2(5)
112.2(5)
110.5(2)
108.1(2)
molecule B
2.047(5)
2.083(5)
2.071(5)
2.2999(15)
1.287(8)
1.818(5)
1.231(8)
1.332(6)
1.211(6)
1.508(8)
1.345(7)
1.475(7)
86.09(19)
86.90(19)
95.96(14)
91.40(14)
124.9(6)
119.5(6)
115.5(6)
123.5(5)
125.3(4)
110.2(4)
120.2(4)
126.4(4)
112.0(3)
124.1(5)
123.1(5)
112.6(5)
110.7(2)
111.2(2)
Pt(1)-C(34)
Pt(1)-C(1)
Pt(1)-C(7)
Pt(1)-P(1)
O(1)-C(32)
P(2)-C(33)
O(2)-C(32)
O(3)-C(35)
O(4)-C(35)
C(32)-C(33)
C(33)-C(34)
C(34)-C(35)
C(34)-Pt(1)-C(7)
C(1)-Pt(1)-C(7)
C(34)-Pt(1)-P(1)
C(1)-Pt(1)-P(1)
O(2)-C(32)-O(1)
O(2)-C(32)-C(33)
O(1)-C(32)-C(33)
C(34)-C(33)-C(32)
C(34)-C(33)-P(2)
C(32)-C(33)-P(2)
C(33)-C(34)-C(35)
C(33)-C(34)-Pt(1)
C(35)-C(34)-Pt(1)
O(4)-C(35)-O(3)
O(4)-C(35)-C(34)
O(3)-C(35)-C(34)
C(49)-P(2)-C(33)
C(37)-P(2)-C(33)
F igu r e 2. Thermal ellipsoid plot of molecule A of complex
1a . Phenyl groups (except Cipso) and H atoms have been
omitted for clarity. Non-hydrogen atoms are drawn at the
30% probability level.
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t
for 1a ‚CH2Cl2
formula
[C55H36Cl2F10O4P2Pt]
mol wt
1278.77
data collection T, K
297(2)
λ, Å
0.71073
monoclinic
P21/c
21.338(6)
cryst syst
space group
a, Å
mental error. The comparison of these bond distances
with those found in related platinum-carbene com-
plexes, in which the carbene ligand is located trans to
another carbon atom [range 2.00(2)-2.079(13) Å],17
shows that this Pt-C bond has some double-bond
character. Moreover, these bond distances fall near the
lower limit of the range of distances found for Pt-C(sp2)
bonds trans to another carbon atom; for instance, the
range is 2.043(13)-2.104(5) Å in Pt-C(phenyl) deriva-
tives.17 In addition, the C-C bond distances C(33A)-
C(34A) [1.339(6) Å] and C(33B)-C(34B) [1.345(7) Å] are
slightly longer than those usually found for olefinic
C(sp2)-C(sp2) bonds [range 1.326-1.331 Å] and very
nearly equal to the mean value found from unconjugated
CdC-CdO systems [1.330(8) Å],18 but are clearly
shorter than the C(sp2)-C(sp2) single bonds found in
the same molecule, for instance, C(34A)-C(35A) [1.490-
(7) Å], C(32A)-C(33A) [1.489(7) Å], C(34B)-C(35B)
[1.475(7) Å], and C(32B)-C(33B) [1.508(8) Å]. The
multiple-bond character of the C(33A)-C(34A) and
C(33B)-C(34B) bonds is also reflected in the values
found for the bond angles around C(34A) (sum of
angles: 358.4°), C(33A) (359.2°), C(34B) (358.6°), and
C(33B) (359.0°) and in the dihedral angles Pt(1A)-
C(34A)-C(33A)-P(2A) [-167.3(5)°], Pt(1A)-C(34A)-
C(33A)-C(32A) [0.6(5)°], Pt(1B)-C(34B)-C(33B)-P(2B)
[167.2(5)°], and Pt(1B)-C(34B)-C(33B)-C(32B) [-1.0-
b, Å
c, Å
â, deg
V, Å3
Z
13.216(4)
37.126(10)
102.248(6)
10231(5)
8
D
calc, Mg m-3
1.660
2.993
5040
µ (Mo KR), mm-1
F(000)
cryst size, mm
θ range, deg
0.228 × 0.108 × 0.103
0.98-27.48
no. of reflns collected/unique
no. of data/restraints/params
GOF
71858/23443 [Rint ) 0.0484]
23443/66/1374
1.022
R indices [I>2σ(I)]a
R indices (all data)a
largest peak, hole, e‚Å-3
R1 ) 0.0391, wR2 ) 0.0875
R1 ) 0.0853, wR2 ) 0.1045
1.202, -1.535
R1 ) ∑||Fo| - |Fc||/∑|Fo|; wR2 ) [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2
;
a
2
GOF ) [∑w(Fo - Fc2)2/(nobs - nparam)]1/2
.
2
bond distances and angles are collected in Table 2. The
two molecules show essentially identical bond distances
and angles, with differences arising in the relative
orientations of phenyl and carbomethoxy groups. In
each molecule, the platinum atom is located in a slightly
distorted square-planar environment, bonded to the
ipso carbon atoms of the C6F5 ligands, to the P atom
of the PPh3 group, and to the carbenic carbon atom of
the ylide-carbene ligand. Thus, it is clear that the
reaction occurs with activation of one of the P-C bonds
in the starting bis-ylide, generation of the PPh3 and
:C(CO2Me)-C(CO2Me)(PPh3) groups, and coordination
of these resulting fragments in mutually cis positions
after displacement of the THF molecules (see eq 1).
The Pt-C(C6F5) bond distances [2.076(5), 2.079(5),
2.071(5), and 2.083(5) Å] are identical, within experi-
mental error, and fall in the usual range of distances
found for this type of bond.16 The Pt-C(carbene) bond
distances Pt(1A)-C(34A) [2.056(5) Å] and Pt(1B)-
C(34B) [2.047(5) Å] are also identical, within experi-
(16) Falvello, L. R.; Fornie´s, J .; Navarro, R.; Rueda, A.; Urriolabeitia,
E. P. Organometallics 1996, 15, 309.
(17) (a) Hartley, F. R. In Comprehensive Organometallic Chemistry
I; Abel, E. W., Stone, F. G. A., Wilkinson, G., Editors-in-chief; Pergamon
Press: Oxford, 1982. Vol. 6, p 502 and ff. (b) Pruchnik, F. P. In
Organometallic Chemistry of the Transition Elements; Plenum Press:
1990; Chapter 5, p 277 and ff.
(18) (a) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.;
Orpen, A. G.; Taylor, R. J . Chem. Soc., Perkin Trans. 2 1987, 685. (b)
Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A. G.;
Taylor, R. In International Tables for Crystallography; Wilson, A. J .
C., Ed.; 1995; Vol. C., Table 9.5, pp 685-706.

Stabilized Bis-ylides
Organometallics, Vol. 22, No. 5, 2003 1135
F igu r e 3. Resonance forms for complex 1a .
(5)°]. The planarity of the fragments Pt(1)-C(34)-
C(33)-P(2) (A and B) can also be observed in the
deviations of their component atoms with respect to the
best least-squares planes (maximum 0.08 and 0.09 Å,
respectively). Moreover, these planar fragments Pt-C-
C-P are nearly perpendicular to the coordination plane
(calculated using Pt(1)-P(1)-C(1)-C(7)-C(34), A and
B), the dihedral angles between the respective best
least-squares planes being, respectively, 84.1(5)° and
88.2(6)°.
The P(2A)-C bond distances are identical, within
experimental error [and the same is true for the bond
distances P(2B)-C], and all of them are longer than
those expected for an ylidic PdC bond, even in the case
of stabilized ylides (average value 1.71 Å).11 This fact
implies that the P-C bonds do not possess multiple-
bond character, that they are not involved in any process
of charge delocalization, and, consequently, that the
environment around the phosphorus atom is that of a
phosphonium moiety. Moreover, the carbomethoxide
groups are not involved in any charge delocalization,
as can be seen from the CdO bond distances C(35A)-
O(4A) [1.197(6) Å], C(32A)-O(2A) [1.200(6) Å], C(35B)-
O(4B) [1.211(6) Å], and C(32B)-O(2B) [1.231(8) Å],
typical for carbonyl groups.18
In summary, the Pt-CR and the CR-Câ bond dis-
tances show multiple bond character, but no other bond
is involved in charge delocalization. In Figure 3 we have
represented the limiting resonant forms inferred from
the X-ray data (1a 1 and 1a 2). Between the two limiting
structures, it is sensible to assume that the form 1a 1
predominates in the bonding description, since the
P+‚‚‚C- interaction in 1a 2 would be inconsistent with
the long P-Câ bond distances found. Very similar
bonding descriptions have been reported in the litera-
ture for Re,13b,c Cr, Mo, and W,12b Mn,12c,13a and Pt14
derivatives. In all cases the authors suggest that the
vinyl structure best represent the bonding mode, with
a small contribution (but not negligible) of the ylide-
carbene form.
spectra show signals typical of organometallic C6F5
ligands (see Experimental Section). In the Fortho region
(-116 ppm for 1a and -112 ppm for 1b ), it is pos-
sible to observe four different peaks, corresponding to
the four Fortho nuclei present in the molecule. This fact
implies that (i) the two C6F5 groups are chemically
inequivalent, since the trans ligands are different; (ii)
the molecular plane is not a symmetry plane, due to
the asymmetry imposed by the carbene ligand; and (iii)
the two C6F5 groups and the carbene ligand are not
able to rotate freely around the M-C bond, probably
due to the presence of the bulky PPh3 ligand and the
carbene. Meanwhile, the 31P{1H} NMR spectra of 1a and
1b show clearly the presence of two different P atoms
in each compound. For 1a the signals are easily as-
signed, due to the presence of 195Pt satellites: the PPh3
ligand appears at 14.27 ppm (1J Pt-P ) 2725 Hz) and
the P atom of the ylide carbene appears at 16.50
ppm (3J Pt-P ) 265 Hz). In the case of 1b the PPh3 ligand
appears at 20.85 ppm (broadened by the presence of
the trans-C6F5 ligand) and the P atom of the ylide
carbene appears at 13.42 ppm (sharp singlet). The
positions of the resonances attributed to the P atom
of the carbene ligand are very near to those found
for resonance-stabilized ylides,11 showing that the
form 1a 2 does actually contribute to the bonding de-
scription.
The 13C{1H} NMR spectrum of 1a is particularly
informative. The resonance attributed to the carbenic
carbon atom (CR) in the group Pt-CR-Câ-P appears at
214.71 ppm (1J Pt-C ) 665 Hz), showing unambiguously
its carbenic nature and the contribution of the canonical
form 1a 2 to the bonding description. The chemical shift
values for carbenic carbons appear in the range 170-
330 ppm,20 but the main body of data appear between
200 and 250 ppm, with values of the coupling constant
1J Pt-C in the range 700-1100 Hz.20 On the other hand,
the chemical shift values for the CR in vinyl derivatives
of Pt(II) appear in the range 110-190 ppm, high-field
shifted with respect to the values found for carbene
derivatives.20 As we can see, the values observed for
1a clearly show the carbenic nature of the CR carbon
atom. The carbonyl groups appear as doublets at 171.77
The spectroscopic characterization of 1a and 1b
provides additional structural information. The IR
spectra of these complexes show typical bands due to
the presence of cis-C6F5 ligands16 and strong carbonyl
absorptions at 1698 cm-1 (1a ) and 1699 cm-1 (1b). The
positions of the carbonyl bands show that these
groups are not involved in charge delocalization pro-
cesses since, in that case, this absorption should appear
at lower energies. For instance, the CO stretch in the
starting bis-ylide7 appears at 1598 cm-1 and in the
resonance-stabilized P-ylide Ph3PdC(H)CO2Me at 1621
ppm (3J PC ) 15.1 Hz) and at 168.66 ppm (2J PC
)
24.3 Hz), the signal attributed to the Câ appears at
3
110.21 ppm (1J PC ) 73.4 Hz, J PC ) 1.9 Hz), and the
OMe carbons appear at 52.45 and 50.42 ppm, in addi-
tion to the expected resonances due to the Ph groups
and the C6F5 ligands, the latter showing very low
intensity.
cm-1 19 The 1H NMR spectra of 1a and 1b are very
.
(19) Isler, O.; Gutmann, H.; Montavon, M.; Ruegg, R.; Ryser, G.;
Zeller, P. Helv. Chim. Acta 1957, 40, 1242.
similar and show signals corresponding to the aromatic
(20) Mann, B. E.; Taylor, B. F. 13C NMR Data for Organometallic
Compounds; Academic Press: London, 1981; pp 141-142.
protons and to the carbomethoxy groups. The 19F NMR

1136 Organometallics, Vol. 22, No. 5, 2003
Falvello et al.
Due to the singularity of this reactionsa stabilized
bis-ylide as a carbene transfer reagentswe have carried
out a series of reactions, changing the starting material
(neutral vs cationic; Pd vs Pt) and the number of
available positions (bis-solvato vs mono-solvato) in order
to check the generality of the process.
ment is preserved in complexes 2-6, only geometric
isomers should be considered.
In the case of complexes 2 and 3 (see eq 2.1), their
geometry is clearly inferred from the 31P{1H} NMR
spectra. The spectrum of 2 shows three signals, each
as a doublet of doublets with 195Pt satellites. The
resonance attributed to the orthometalated P atom
Several orthometalated, cationic, bis-solvato deriva-
tives have been allowed to react with the bis-ylide
[Ph3PdC(CO2Me)-C(CO2Me)dPPh3]. The bis-solvato
complexes were prepared by reaction of the correspond-
ing orthometalated [M(C∧X)(µ-hal)]2 derivatives with
AgClO4 (1:2 molar ratio, THF, rt) followed by removal
of the silver halide by filtration. The freshly prepared
solutions of [M(C∧X)(THF)2]ClO4 react with the bis-
ylide (1:1 molar ratio, THF, rt), yielding the new carbene
complexes [M(C∧X){C(CO2Me)-C(CO2Me)(PPh3)}(PPh3)]-
ClO4 (C∧X ) o-CH2C6H4P(o-tolyl)2, M ) Pt, 2; M ) Pd,
3; M ) Pd, C∧X ) CH2C9H6N-C8,N, 4; NC5H4-o-C6H4,
5; C13H8N, 6) as air-stable solids (see schematic dia-
grams of complexes 2-6 in eqs 2.1 and 2.2). The
analytical data and mass spectra of 2-6 are in good
agreement with the incorporation of a bis-ylide to each
[M(C∧X)]ClO4 fragment.
2
appears at 28.25 ppm (4J PP ) 35.3 Hz, J PPcis ) 14.8
1
Hz, J PtP ) 2519 Hz), the signal assigned to the PPh3
2
ligand at 18.95 ppm (4J PP ) 5.6 Hz, J PPcis ) 14.8 Hz,
1J PtP ) 2056 Hz), and that due to the -C(PPh3) group
4
3
at 15.57 ppm (4J PP ) 35.3 Hz, J PP ) 5.6 Hz, J PPt
)
2
305 Hz). The small value of the J PP coupling constant
shows clearly that the two coordinated P atoms are
mutually cis, since a P-trans-to-P arrangement is re-
flected in typical 2J PP values of about 450 Hz.21 Similar
conclusions can be derived from the 31P{1H} NMR
1
spectrum of 3. Furthermore, the H NMR spectra of 2
and 3 show, in addition to the phenyl, CO2Me, and
Me(tolyl) resonances, signals assigned to the diaste-
reotopic M-CH2 protons, which appear as an AB spin
system coupled with 31P. This fact implies that the
metalated CH2 group and the PPh3 ligand are located
mutually trans and, as has been described for 1a and
1b, that the molecular plane is not a symmetry plane
due to the restricted rotation of the carbene ligand
around the M-C bond.
The 13C{1H} NMR spectrum of 2 shows a signal at
217.21 ppm, attributed to the carbene CR atom, as a
2
doublet of doublets (2J PtransC ) 109 Hz, J PC ) 8.5 Hz),
in keeping with the P-trans-to-C arrangement. As
expected, the signal assigned to the metalated methyl-
ene appears at 37.09 ppm as a doublet (2J PtransC
)
87.1 Hz), and the Câ atom appears as a doublet of
3
doublets (1J PC ) 70.9 Hz, J PC ) 2.7 Hz). Similar
conclusions can be inferred from the analysis of the
NMR spectra of 3, although in this case we have not
been able to observe the signals due to the CR and Câ
atoms, even with long accumulations. On the basis of
all these data, we propose the structures shown in eq
2.1 for 2 and 3.
In the case of complexes 4-6, the formation of the
carbene ligands can be clearly seen from the analysis
of the 13C{1H} NMR spectra. In fact, signals at 220.69
ppm (dd, J PC ) 14.1 Hz, J PC ) 10.2 Hz, 5) and at 219.67
ppm (dd, J PC ) 13.1 Hz, J PC ) 9.9 Hz, 6) are attributable
to CR of the carbene ligand. In addition, Câ appears at
The spectroscopic characterization of 2-6 shows
unambiguously that each of these compounds also
contains a PPh3 group and a carbene ligand and that a
similar P-C bond activation process could be involved
here. The IR spectra of 2-6 show strong absorptions in
the 1700 cm-1 region, attributed to the carbonyl stretch.
The particular position in each complex varies slightly
from one to another [range 1693-1724 cm-1], but all of
them fall in the same region as that described for 1a
and 1b, suggesting a similar environment.
The NMR spectra of 2-6 show only one set of
resonances in each spectrum, showing that each com-
plex appears as a single isomer. Due to the asymmetric
nature of the metalated ligands and the different
electronic and steric requirements of the donor atoms
bonded to the metal, one could expect, at first glance,
the formation of different isomers, either geometric (cis/
trans) or conformational isomers, arising from the
relative disposition of the carbomethoxy groups around
the CR-Câ bond (Z/E). In the crystal structure of 1a we
see that the configuration of the two CO2Me groups
around the C-C bond is E. Assuming that this arrange-
1
110.06 ppm (d, J PC ) 77.4 Hz, 5) and at 110.14 ppm
1
3
(dd, J PC ) 71.2 Hz, J PC ) 3.8 Hz, 6), and it is also
possible to observe signals corresponding to the different
orthometalated ligands (see Experimental Section).
Moreover, the 31P{1H} NMR spectra of 4-6 show two
signals in all cases, corresponding to the presence of the
two different types of P atoms, and the 1H NMR spectra
show the presence of all the expected resonances. With
respect to the ligand arrangements in complexes 4-6,
we propose the structure shown in eq 2.2, that is, the
PPh3 ligand trans to the N atom, on the basis of the
known aversion of the PPh3 ligand to be coordinated
trans to an aryl C atom (transphobia).22 This works well
for the aryl complexes 5 (ortho-phenylpyridine) and 6
(benzo[h]quinoline), where there are no reports of or-
(21) Ferna´ndez, S.; Garc´ıa, M. M.; Navarro, R. Urriolabeitia, E. P.
J . Organomet. Chem. 1998, 561, 67.

Stabilized Bis-ylides
Organometallics, Vol. 22, No. 5, 2003 1137
thopalladated complexes containing the P-trans-C ar-
rangement. For complex 4 this proposal is also sustain-
able due to the observation, in the 13C{1H} NMR
spectrum, of a signal at 38.55 ppm (attributed to the
Pd-CH2 atom) with triplet structure (J PC ) 5.1 Hz). The
small value of the coupling constant could be due to the
coupling with the cis P atom and with the remote P
atom of the trans carbene ligand.
In summary, neutral or cationic bis-solvato deriva-
tives of Pd(II) and Pt(II) with strongly coordinated
ancillary ligands are able to promote, under very mild
conditions, one P-C bond cleavage in the R-stabi-
lized bis-ylide Ph3PdC(CO2Me)-C(CO2Me)dPPh3, gen-
erating two fragmentssPPh3 and the ylide-carbene
[:C(CO2Me)-C(CO2Me)PPh3]swhich in turn coordinate
to the metal center.
2. Rea ction s of th e Bis-ylid e w ith Mon o-solva ted
Sp ecies. Further extension of the work developed in
Section 1 arises from the question, What happens when
only one position is available? Since in the PdC bond
activation process two ligands with very different
electronic and steric requirements are formedsand with
quite different metal-to-ligand bond energiessa selec-
tive coordination of only one of the two fragments can
be anticipated. Some examples are presented as sche-
matic diagrams in eqs 3, 4, and 5.
CH2C9H6N-C8,N, 8) following the process described in
eq 3. These bis-phosphino derivatives are isolated from
the reaction mixture by THF evaporation and Et2O
addition. The evaporation of the ether solution gives an
oily residue, which can be characterized spectroscopi-
cally as a mixture of OdPPh3 and dimethylfumarate
(scant amounts of the isomeric dimethylmaleate were
detected in some experiments). Complexes 7 and 8 give
satisfactory elemental analyses and mass spectra in
accord with the proposed structure. The incorporation
of a PPh3 ligand into the starting solvato complex is
clearly inferred from the 31P{1H} NMR spectra of 7 and
8. Thus, the spectrum of 7 shows the presence of three
different resonances, corresponding to the three in-
equivalent P atoms present in the molecule, while the
spectrum of 8 shows the two signals expected (see
Experimental Section).
In the same way, the reaction of the solvato deriva-
tives [Pd(C6F5)(L-L)(THF)]ClO4 with the bis-ylide (1:1
molar ratio, dry THF, rt) affords the phosphino com-
plexes [Pd(C6F5)(L-L)(PPh3)]ClO4 (L-L ) 2,2′-bipyri-
dine; Ph2PCH2CH2PPh2) as per the process reported in
eq 4, and the reaction of (NBu4)[Pt(C6F5)3(CO)] with the
bis-ylide, under the same reaction conditions, gives
(NBu4)[Pt(C6F5)3(PPh3)], as presented in eq 5. These
complexes have been isolated from the reaction mixtures
after solvent evaporation and Et2O addition, and char-
acterized as described previously.23 As expected, the
spectroscopic characterization of the residue obtained
after evaporation of the ether solution showed it to be
a mixture of OdPPh3 and dimethylfumarate.
In light of these facts, it seems that the reaction of
the monosolvato complexes with the bis-ylide also occurs
through PdC bond activation and generation of the
PPh3 ligand and the carbene fragment. However, only
the PPh3 ligand remains coordinated to the metal
center, affording the corresponding phosphino deriva-
tives, while the carbene ligand decomposes, probably
due to reaction with water, giving OdPPh3 and di-
methylfumarate. This decomposition of the carbene
fragment has already been reported in the literature,7a
and the presence of water could be due to the exposure
of the reaction mixture to air at the end of the reaction.
In an attempt to trap the carbene ligand, the reaction
of [Pt(THF)(CH2C6H4-o-P(o-tol)2)(PPh3)]ClO4 with the
bis-ylide was carried out in strictly anhydrous conditions
and in the presence of an excess of styrene. In this reac-
tion, complex 7 was again obtained; however none of
the anticipated cyclopropanation product was obtained.
Some questions about the synthesis of 1-8 arise at
this point: (i) How is the PdC bond activation produced;
(ii) how is the PPh3 fragment transferred to the metal
center; and (iii) is it an inter- or intramolecular transfer?
The answer to the first question can be inferred easily
from the reported hydrolysis of this bis-ylide.7a This
hydrolysis (in boiling water) generates equimolecular
amounts of PPh3, OdPPh3, and dimethyl fumarate,
through an initial protonation of one of the ylidic units,
expulsion of the PPh3 fragment, and hydrolysis of the
resulting vinyl phosphonium salt. In line with this, it
is reasonable to assume that in our reaction the first
step is the C-bonding of the bis-ylide to the metal center
The reaction of the solvato derivatives [M(C∧X)(THF)-
(PPh3)]ClO4sobtained from the corresponding halo-
derivatives by abstraction of the halide with AgClO4 (see
Experimental Section)swith the bis-ylide (1:1 molar
ratio, dry THF, rt) affords, after the usual workup, the
bis-phosphino complexes [M(C∧X)(PPh3)2]ClO4, (M ) Pt,
C∧X ) o-CH2C6H4P(o-tolyl)2, 7; M ) Pd, C∧X )
(22) (a) Vicente, J .; Arcas, A.; Bautista, D.; J ones, P. G. Organome-
tallics 1997, 16, 2127. (b) Vicente, J .; Abad, J . A.; Frankland, A. D.;
Ram´ırez-de-Arellano, M. C. Chem. Eur. J . 1999, 5, 3066.
(23) Uso´n, R.; Fornie´s, J . Adv. Organomet. Chem. 1988, 28, 219, and
references therein.

1138 Organometallics, Vol. 22, No. 5, 2003
Falvello et al.
(a Lewis acid) (see eq 6). After this coordination, the
solvato complexes with two monodentate, monoanionic,
ligands (C6F5) or cationic bis-solvato derivatives with
chelating monoanionic ligands. The reactivity of cationic
bis-solvato precursors with two monodentate ligands,
one neutral and one anionic (SC4H8 ) tht, PPh3, and
C6F5), toward the bis-ylide results in the synthesis of a
new type of compound.
The intermediate bis-solvato complexes [Pd(C6F5)(L)-
(THF)2]ClO4 (L ) tht, PPh3) were prepared by reaction
of the corresponding halide-bridged dinuclear complexes
with AgClO4 (1:2 molar ratio) in THF at room temper-
ature. After removal of the AgCl, the freshly prepared
solutions were allowed to react with the bis-ylide (Pd/
bis-ylide ) 1:1), giving, after a few minutes, yellow
solutions. The reaction products were isolated either by
direct precipitation in THF (L ) tht, 9) or by removal
of the solvent and Et2O addition (L ) PPh3, 10).
Complexes 9 and 10 have been characterized spectro-
scopically as the metallacyclopropane derivatives shown
in eq 7 on the basis of the following observations.
electron density remaining in the remote, nonbonded
ylide could be delocalized through the Câ-CR-M sys-
tem, promoting the 1,2-shift of the PPh3 group from the
CR to the metal. This latter shift can be explained in
terms of the Lewis acid nature of the metal, taking into
account the high affinity of the metal (Pd, Pt) for
phosphine ligands. Thus, it seems that the presence of
the second, “remote” ylide unit is decisive in achieving
the PdC bond activation in the first.
The process proposed in eq 6 seems to involve an
intramolecular transfer of the PPh3 group from CR to
the metal. We have discarded the hypothesis of an
intermolecular transfer of PPh3 since, in that case, free
PPh3 should be present in the reaction medium. This
free PPh3 would be able to react with other species
present in the solution, for instance the starting bis-
solvato derivatives, giving bis-phosphino complexes.
This side reaction would be more likely to occur in the
early stages of the reaction, when the concentration of
the bis-solvato complexes is high. However, we have not
detected the formation of bis-phosphino derivatives in
the syntheses of 1-6. Moreover, we have carried out
the reaction of the bis-solvate Pt(C6F5)2(THF)2 with the
bis-ylide in molar ratio 2:1, that is, in the presence of
an excess of solvato complex, using the same experi-
mental workup as that described for 1a . The first
fraction, insoluble in Et2O, was identified as pure 1a ;
the second one, insoluble in n-hexane, was identified as
Pt(C6F5)2(THF)2, and we have not detected the presence
of Pt(C6F5)2(PPh3)2, even at trace levels.
This reaction scheme also helps explain why in the
case of monosolvato starting compounds only the bis-
phosphino complexes 7 and 8 were obtained. Since only
one coordination site is available, the ligand with the
highest bond formation energy remains coordinated.
The syntheses of 7 and 8 through a 1,2-shift of the PPh3
group from the coordinated CR to the metal center and
elimination (probably at the same time) of the carbene
fragment also imputes an intramolecular (rather than
intermolecular) migration of the PPh3. An intermolecu-
lar mechanism for the synthesis of 8 would be formally
equivalent to the reaction of 4 with PPh3, and, in fact,
complex 4 does not react with PPh3 in THF at room
temperature.
The elemental analyses of 9 and 10 are in good
agreement with the incorporation of one bis-ylide unit
to each [Pd(C6F5)(L)(ClO4)] fragment. However, the
spectroscopic characterization of 9 and 10 shows clearly
that they are not ylide-carbene complexes analogous to
1-6. The mass spectrum of 9 shows peaks at 939 amu,
corresponding to the loss of the tht ligand, at 677 amu
(loss of the tht and PPh3 ligands) and at 571 amu (loss,
in addition, of the Pd atom). All peaks show correct
isotopic distributions. In fact, the isotopic distribution
of the peak at 571 amu is in good agreement with that
expected for the cation [(C6F5)(C(CO2Me)-C(CO2Me)-
(PPh3)]+, generated by addition of the C6F5 group to the
ylide-carbene ligand, suggesting that the C6F5 group is
no longer organometallic. The same conclusions can be
derived from the mass spectrum of 10.
The loss of the organometallic nature of the C6F5
fragment is also inferred from the IR spectra and,
unambiguously, from the 19F NMR spectra of 9 and 10.
In the IR spectra, the typical absorptions of metalated
C6F5 groups (1630, 1500, 1060, 950, and 780 cm-1) have
been replaced by those characteristic of C6F5 bonded to
a carbon atom (1650, 1515, 1490, 1130, 990, and 950
cm-1),24 although, due to the presence of the ClO4 and
CO2Me groups, some absorptions appear overlapped.
The 19F NMR spectrum of 9 shows the presence of two
set of signals, corresponding to the presence of two
3. Migr a tor y In ser tion Rea ction s. Syn th esis of
Meta lla cyclop r op a n e Com p lexes. In the syntheses
of 1-6 we have used as starting materials neutral bis-

Stabilized Bis-ylides
Organometallics, Vol. 22, No. 5, 2003 1139
ligand, were not observed in the 13C{1H} NMR spectra
of 9 and 10, despite the utilization of long accumulation
periods.
Sch em e 1
The synthesis of 9 and 10 can be understood as a
formal migratory insertion of the carbene ligand into
the Pd-C(C6F5) bond. It is reasonable to assume that
the first step of the reaction is the PdC bond activation
and the generation of the corresponding phosphino-
(ylide-carbene) derivatives (see eq 7), analogous to
complexes 1-6, although in this case these intermedi-
ates could not be detected. These intermediates could
be obtained, in principle, as a mixture of three isomers
(C6F5 cis to carbene and cis to tht; C6F5 cis to carbene
and cis to PPh3; and C6F5 trans to carbene; see Scheme
2) with different populations in accord with their mutual
trans influences.22 The cis arrangement of the C6F5 and
carbene ligands is a prerequisite to the migratory
insertion process, while a trans configuration obviates
this type of reaction.25 However, since 9 is obtained as
two isomers, it is reasonable to suppose that, either
before or after the migratory insertion process, an
isomerization process exchanges the positions of the tht
and PPh3 ligands; such isomerizations are not rare in
Pd(II) complexes.26
In a second step, a migratory insertion reaction of the
carbene ligand into the Pd-C(C6F5) bond takes place.
This reaction can be seen either as migratory insertion
or as nucleophilic attack of the C6F5 ligand, and both
points of view are well documented in the literature for
Pd(II) complexes.24,27 This reaction is worthy of note,
due to the remarkable stability of the M-C(C6F5)
bonds,23 which allow the synthesis of derivatives 1a and
1b, for instance. As a result of the migratory insertion
process, the carbenic CR atom becomes a σ-alkyl C atom
(sp3 hybridyzed), bonded to palladium, and also the pure
ylide functionality is restored. The last step is simply
the coordination of the ylidic carbon Câ at the vacant
coordination site generated after the migration of the
C6F5 group, in such a way that a metallacyclopropane
derivative is obtained. Very few examples of metalla-
cyclopropanes with phosphonium substituents have
been reported in the literature.28 This type of complex
has been obtained through different synthetic routes,
the main one being the nucleophilic attack (intra- or
intermolecular) of a PR3 group on a σ-vinyl ligand.28a,d-g
The labile tht ligand in the mixture 9 can easily be
displaced from the coordination sphere of palladium by
addition of other ligands. Thus, the addition of PPh3 to
a CDCl3 solution of 9 (see Experimental Section) gives
an equilibrium mixture between 9, 10, free tht, and
PPh3. When bidentate phosphines are used, such as
dppm [Ph2PCH2PPh2] or dppe [Ph2PCH2CH2PPh2], the
new complexes 11a (dppm) and 11b (dppe) are obtained
isomers (1:5 molar ratio), while that of 10 shows only
one set of signals. Each set comprises five different
peaks, corresponding to the five chemically inequivalent
F atoms, thus showing that the C6F5 groups do not have
free rotation around the C-Cipso(C6F5) bond. For
complex 9 the signals attributed to the Fortho nuclei
appear between -131.35 and -136.29 ppm, shifted to
high field more than 10 ppm with respect to the starting
compound (-121.23 ppm for [Pd(µ-Cl)((C6F5)(tht)]2) and
in a region typical for C-C6F5 groups.24 For 10 these
signals appear between -129.9 and -131.3 ppm.
The assignment of the structures 9a for the major
isomer and 9b for the minor isomer shown in Scheme 1
has been carried out through the analysis of the
31P{1H} NMR spectrum of 9. The signals corresponding
to the minor isomer 9b appear as doublets at 29.08 ppm
3
(PA) and at 23.18 ppm (PB) with J PP ) 18.2 Hz, while
those corresponding to the major isomer 9a appear as
a singlet at 28.56 ppm (PA) and a doublet at 25.92 ppm
(PB, J ) 26 Hz). The pseudo-trans arrangement of the
P atoms in 9b could account for the observation of P-P
coupling, which is not observed in 9a due to their
pseudo-cis disposition. Moreover, PB in 9a appears as a
doublet and is arranged pseudo-trans with respect to
the C6F5 group, as reflected in the coupling constant J PF
) 26 Hz, which also appears in the 19F NMR spectrum.
For the major isomer 9a , one of the Fortho signals
(-134.04 ppm) appears as a doublet (J FF), while the
other (-134.25 ppm) appears as a triplet (J PF ≈ J FF).
As expected, the 31P{1H} NMR spectrum of 10 (see
Scheme 1) shows three resonances. The signal at 29.97
ppm, attributed to PA, appears as a doublet (J AB ) 17.5
Hz) due to the coupling with PB, which appears at 23.22
ppm as a doublet of doublets (J AB ) 17.5 Hz, J BC ) 26.0
Hz). Also, the signal assigned to PC appears as a triplet
(instead of the expected doublet due to “only P-P
coupling”) due to the PBPC coupling and to the PC-Fortho
coupling, which is once again observed in the 19F NMR
spectrum of 10 (signal at -131.30 ppm). Unfortunately,
the resonances from the metalated CR and Câ carbon
atoms, which could have provided definitive proof of the
incorporation of the C6F5 group into the ylide-carbene
(25) Thorn, D. L.; Hoffmann, R. J . Am. Chem. Soc. 1978, 100, 2079.
(26) Minitti, D. Inorg. Chem. 1994, 33, 2631.
(27) (a) Albe´niz, A. C.; Espinet, P.; Lin, Y.-S. Tetrahedron 1998, 54,
13851. (b) Albe´niz, A. C.; Espinet, P.; Lin, Y.-S. Organometallics 1997,
16, 5964. (c) Albe´niz, A. C.; Casado, A. L.; Espinet, P. Organometallics
1997, 16, 5416. (d) Albe´niz, A. C.; Espinet, P.; Lin, Y.-S. Organome-
tallics 1997, 16, 4138. (e) Albe´niz, A. C.; Espinet, P.; Lin, Y.-S.
Organometallics 1997, 16, 4030. (f) Albe´niz, A. C.; Espinet, P.; Lin,
Y.-S. J . Am. Chem. Soc. 1996, 118, 7145. (g) Albe´niz, A. C.; Espinet,
P.; Lin, Y.-S.; Orpen, A. G.; Mart´ın, A. Organometallics 1996, 15, 5003.
(h) Albe´niz, A. C.; Espinet, P.; Lin, Y.-S. Organometallics 1996, 15,
5010. (i) Albe´niz, A. C.; Espinet, P.; Lin, Y.-S. Organometallics 1995,
14, 2977. (j) Albe´niz, A. C.; Espinet, P. J . Organomet. Chem. 1993,
452, 229. (k) Albe´niz, A. C.; Espinet, P.; J eannin, Y.; Philoche-
Levisalles, M.; Mann, B. E. J . Am. Chem. Soc. 1990, 112, 6594.
(24) (a) Albe´niz, A. C.; Espinet, P.; Foces-Foces, C.; Cano, F. H.
Organometallics 1990, 9, 1079. (b) Uso´n, R.; Fornie´s, J .; Espinet, P.;
Lalinde, E.; J ones, P. E.; Sheldrick, G. M. J . Chem. Soc., Dalton Trans.
1982, 2389.

1140 Organometallics, Vol. 22, No. 5, 2003
Falvello et al.
Sch em e 2
(see Scheme 1), and, in this case, unreacted 9 was not
detected. Complexes 11a and 11b were characterized
only spectroscopically in CD2Cl2 solution. These com-
plexes are rather unstable, and attempts to crystallize
them from these solutions were unsuccessful, due to the
formation of several unidentified species. The 19F NMR
spectra of 11a and 11b are very similar to those
described for 9 and 10 and can be analyzed in the same
terms. The 31P{1H} NMR spectra show four signals,
corresponding to the expected four different P atoms.
Three of these peaks appear in the low-field region, and
the observed coupling pattern is very similar to that
reported for 10, while the remaining resonance appears
at high field (-21.70 ppm for 11a ; -14.86 ppm for 11b),
clearly indicating the presence of a nonbonded P atom.
starting materials, taking into account, moreover, that
carbene complexes of Hg(II) are known and stable.29
However, our first attempts using HgCl2 or HgPh2 (Ph
) phenyl) were unsuccessful, and a mixture of the
starting compounds was recovered after 24 h stirring
at room temeparture.
When the starting compound is Hg(OAc)2 (OAc )
acetate), a new reaction takes place. A suspension of
Hg(OAc)2 in dry THF was allowed to react with the bis-
ylide (1:1 molar ratio) for 24 h at room temperature
under Ar atmosphere. After the reaction period, the
solid in suspension was filtered and recrystallized from
CH2Cl2/Et2O, affording white crystals of 12 (see eq 8
4. Rea ctivity of Hg(II) Com p lexes w ith th e Bis-
ylid e. In the preceding paragraphs, we have reported
the PdC bond activation in the bis-ylide Ph3PdC-
(CO2Me)-C(CO2Me)dPPh3 promoted by electrophilic
Pd(II) or Pt(II) complexes, giving carbene complexes,
which can be stable or evolve in different ways. Prompted
by the results obtained, we have begun to explore the
reactivity of other metallic substrates with electrophilic
natures toward the bis-ylide. Salts or simple complexes
of Hg(II) could be considered as good candidates for
(28) (a) Carmona, E.; Gutie´rrez-Puebla, E.; Monge, A.; Mar´ın, J . M.;
Paneque, M.; Poveda, M. L. Organometallics 1989, 8, 967. (b) Alt, H.
G.; Engelhardt, H. E.; Rogers, R. D. J . Organomet. Chem. 1989, 362,
117. (c) Alt, H. G.; Engelhardt, H. E.; Steinlein, E. J . Organomet. Chem.
1988, 344, 227. (d) Rybin, L. V.; Petrovskaya, E. A.; Rubinskaya, M.
I.; Kuz’mina, L. G.; Struchkov, Yu. T.; Kaverin, V. V.; Koneva, N. Yu.
J . Organomet. Chem. 1985, 288, 119. (e) Carmona, E.; Gutie´rrez-
Puebla, E.; Monge, A.; Mar´ın, J . M.; Paneque, M.; Poveda, M. L.
Organometallics 1984, 3, 1438. (f) Nubel, P. O.; Brown, T. L. J . Am.
Chem. Soc. 1984, 106, 644. (g) Scordia, H.; Kergoat, R.; Kubicki, M.
M.; Guerchais, J . E.; L’Haridon, P. Organometallics 1983, 2, 1681.
and Experimental Section). The yield of 12, based on
(29) (a) Clark, A. M.; Oliver, A. G.; Rickard, C. E. F.; Wright, L. J .;
Roper, W. R. Acta Crystallogr., Sect. C 2000, 56, 26. (b) Bildstein, B.;
Malaun, M.; Kopacka, H.; Ongania, K.-H.; Wurst, K. J . Organomet.
Chem. 1998, 552, 45, and references therein. (c) Luger, V. P.; Ruban,
G. Acta Crystallogr., Sect. B 1971, 27, 2276. (d) Scho¨llkopf, U.; Gerhart,
F. Angew. Chem., Int. Ed. Engl. 1967, 6, 970. (e) Scho¨llkopf, U.;
Gerhart, F. Angew. Chem., Int. Ed. Engl. 1967, 6, 560.

Stabilized Bis-ylides
Organometallics, Vol. 22, No. 5, 2003 1141
Hg, is 39.6%. The THF solution was evaporated to
dryness and the residue washed with Et2O, giving a
yellow solid characterized as a mixture of the starting
compounds. Finally, white crystals of the stabilized ylide
13 (45.2% yield based on bis-ylide) were deposited from
the ether solution after standing at room temperature
for an additional 24 h. The yield of complex 12 with
respect to the starting Hg derivative is more or less
similar to that obtained for ylide 13 with respect to the
starting bis-ylide. This fact shows that the reaction has
not reached completion (45% conversion) and also that,
even though the PdC bond activation has taken place,
only the PPh3 ligand remains bonded to the Hg center
while the carbene fragment evolves in a different way
from those reported above (mixtures of OdPPh3 and
dimethyl fumarate).
PPh3 and the carbene [:C(CO2Me)-C(CO2Me)PPh3].
Different products can be obtained as a function of the
starting material. The reaction with bis-solvato com-
plexes of Pd(II) and Pt(II) gives products with both
ligands coordinated to the metal center. In this synthe-
sis of carbene complexes, the bis-ylide behaves as a
genuine carbene transfer reagent. Moreover, in reac-
tions with complexes with only one C6F5 ligand, a
further migratory insertion reaction occurs and metal-
lacyclopropane derivatives are obtained. When mono-
solvato species are used as precursors, the PdC bond
activation promoted by the metal also occurs, but only
the PPh3 ligand remains coordinated and the carbene
ligand decomposes. The synthetic potential of this facile
and unexpected preparative method of carbene com-
plexes as well as their reactivity and applications merit
a detailed study, and further work in this area is
currently in progress.
The characterization of complex 12 clearly reveals the
presence of two acetate ligands and one PPh3 group for
each Hg atom, but we have not determined its nucle-
arity (this type of complex could be mono- or di-
nuclear).30 Typical absorptions due to acetate (1582
cm-1) and PPh3 ligands (700-800 and 500 cm-1 regions)
Exp er im en ta l Section
Sa fety Note: Caution! Perchlorate salts of metal complexes
with organic ligands are potentially explosive. Only small
amounts of these materials should be prepared, and they
should be handled with great caution. See: J . Chem. Ed. 1973,
50, A335-A337.
1
are observed in the IR spectrum of 12, and the H NMR
spectrum shows signals attributed to Ph and Me groups,
respectively, in 15:6 ratio. The 31P{1H} NMR spectrum
shows a singlet resonance with 199Hg satellites (1J HgP
) 8389 Hz), with this value of the coupling constant
similar to those reported in related complexes.31 The
analytical and spectroscopic data for ylide 13 are in good
agreement with the structure depicted in eq 8. Three
strong absorptions can be seen in the carbonyl region:
1740 cm-1 (assigned to the CO fragment), 1671 cm-1
(COOMe terminal, not delocalized), and 1564 cm-1
Gen er a l Meth od s. Solvents were dried and distilled under
argon using standard procedures before use. Elemental analy-
ses were carried out on a Perkin-Elmer 2400-B microanalyzer.
Infrared spectra (4000-200 cm-1) were recorded on a Perkin-
Elmer 883 infrared spectrophotometer from Nujol mulls
between polyethylene sheets. 1H (300.13 MHz), 19F (282.41
MHz), 13C{1H} (75.47 MHz), and 31P{1H} (121.49 MHz)
NMR spectra were recorded in CDCl3, CD2Cl2, or DMSO-d6
solutions at room temperature (unless otherwise stated) on a
Bruker ARX-300 spectrometer; 1H and 13C{1H} were refer-
enced using the solvent signal as internal standard, while
19F and 31P{1H} were externally referenced to CFCl3 and
H3PO4 (85%), respectively. Mass spectra (positive ion FAB)
were recorded from CH2Cl2 solutions on a V. G. Autospec
spectrometer.
cis-[P t(C6F 5)2(P P h 3){C(CO2Me)-C(P P h 3)(CO2Me)}], 1a .
To a solution of (NBu4)2[Pt(µ-Cl)(C6F5)2]2 (0.181 g, 0.113 mmol)
in THF (20 mL) was added AgClO4 (0.047 g, 0.23 mmol). This
mixture was stirred at room temperature with exclusion of
light for 20 min, then the solvent was evaporated to dryness
and the residue extracted with dry Et2O (20 mL). After
removal of the insoluble AgCl and NBu4ClO4, the ether
solutionscontaining cis-Pt(C6F5)2(THF)2swas evaporated to
dryness and the oily residue redissolved with dry THF (15 mL).
The resulting solution was allowed to react with the bis-ylide
Ph3PdC(CO2Me)-C(CO2Me)dPPh3 (0.150 g, 0.225 mmol) for
3 h, giving a pale yellow solution. The evaporation of the
solvent and treatment of the residue with Et2O (10 mL) gives
complex 1a as a white solid, which was filtered, washed with
additional Et2O (10 mL), and air-dried. Obtained: 0.134 g
(49.8% yield). Crystals of complex 1a were obtained by slow
vapor diffusion of Et2O into a CH2Cl2 solution of the title
complex. These crystals contain variable amounts of CH2Cl2
of crystallization.
1
(COOMe in resonance with the ylide function). The H
NMR spectrum displays the expected signals, the
31P{1H} NMR spectrum shows a singlet resonance at
16.60 ppm (typical for resonance stabilized ylides),7,11
and the 13C{1H} NMR spectrum shows, among others,
three signals in the carbonyl region [184.38 ppm (CO),
167.79 and 167.55 ppm (2 COOMe)] and a doublet
resonance at 68.04 ppm (1J PC ) 111.2 Hz) attributed to
the ylidic carbon atom. Although there are numerous
reports of doubly stabilized ylides with similar struc-
tures,32 as far as we are aware the ylide 13 has not
previously been reported.
Even if compounds 12 and 13 can be unambiguously
characterized, the different reactivity observed in this
case (synthesis of 13) already suggests that the decom-
position reaction of the carbene ligand could occur
through different intermediates, in which the acetate
ligand could play an important role. Further work in
this area is in progress.
Con clu sion s
The PdC bond in the bis-ylide Ph3PdC(CO2Me)-
C(CO2Me)dPPh3 can be activated by a variety of elec-
trophilic metal precursors, and this cleavage generates
Anal. Calcd for [C54H36F10O4P2Pt]‚0.25CH2Cl2: C, 53.53; H,
3.02. Found: C, 53.48; H, 3.27. MS (FAB+) [m/z, (%)]: 1196
(10%) [M+], 1029 (80%) [(M - C6F5)+]. IR (ν, cm-1): 1698 (νCd
O). 1H NMR (CD2Cl2, rt): δ (ppm), 7.74-7.18 (m, 30H, Ph),
3.66 (s, 3H, OMe), 2.54 (s, 3H, OMe). 31P{1H} NMR (CD2Cl2,
(30) (a) Ferguson, G.; Alyea, E. C.; Khan, M.; Roberts, P. J .; Parvez,
M. Acta Crystallogr., Sect. A 1978, 34, S128. (b) Alyea, E. C.; Dias, S.
A.; Ferguson, G.; Khan, M. A. J . Chem. Res. (S) 1979, 360.
(31) Berger, S.; Braun, S.; Kalinowski, H.-O. In NMR-Spektroskopie
Von Nichtmetallen: Georg Thieme Verlag: Stuttgart, 1993; Band 3,
31P-NMR-Spektroskopie, p 172.
3
rt): δ (ppm), 16.50 (s, dC(PPh3), J Pt-P ) 265 Hz), 14.27 (s,
1
Pt-PPh3, J Pt-P ) 2725 Hz). 19F NMR (CD2Cl2, rt): δ (ppm),
-115.98 (m, 1F, Fortho, 3J Pt-F ) 304 Hz), -116.72 (m, 1F, Fortho
,
(32) Aitken, R. A.; Karodia, N.; Lightfoot, P. J . Chem. Soc., Perkin
Trans. 2 2000, 333.
3J Pt-F ) 315 Hz), -116.92 (m, 1F, Fortho 3J Pt-F ) 334 Hz),
,

1142 Organometallics, Vol. 22, No. 5, 2003
3J Pt-F ) 304 Hz), -164.61 (t, 1F,
Falvello et al.
-119.77 (m, 1F, Fortho
,
[P d (CH 2C6H 4-o-P (o-t ol)2)(P P h 3){C(CO2Me)-C(P P h 3)-
(CO2Me)}](ClO4), 3. Complex 3 was prepared following an
experimental method similar to that described for 2. [Pd(µ-
Cl)(CH2C6H4-o-P(o-tol)2)]2 (0.100 g, 0.113 mmol) was reacted
with AgClO4 (0.047 g, 0.23 mmol) and with the bis-ylide (0.150
gr, 0.225 mmol) in dry THF to give 3 as a yellow solid.
Obtained: 0.264 g, (96% yield). Complex 3 was recrystallized
from CH2Cl2/Et2O to give yellow crystals of 3‚0.25CH2Cl2. The
amount of CH2Cl2 in the crystals was assayed by integration
of the corresponding resonance in the 1H NMR.
F
para), -165.16 (m, 3F, 2Fmeta + Fpara), -165.88 (m, 2F, Fmeta).
13C{1H} NMR (CD2Cl2, rt): δ (ppm), 214.71 (s, PtdC, 1J Pt-C
)
3
665.0 Hz), 171.77 (d, CO2, J PC ) 15.1 Hz), 168.66 (d, CO2,
2J PC ) 24.3 Hz), 148.82 (m, C6F5), 145.86 (m, C6F5), 138.15
(m, C6F5), 135.14 (d, Cmeta, Ph, 3J PC ) 10.7 Hz), 134.37 (d, Cmeta
,
Ph, 3J PC ) 10.1 Hz), 133.93 (d, Cpara, Ph, 4J PC ) 2.8 Hz), 132.84
1
4
(d, Cipso, Ph, J PC ) 50.9 Hz), 130.17 (d, Cpara, Ph, J PC ) 1.2
Hz), 129.35 (d, Cortho, Ph, 2J PC ) 12.7 Hz), 127.77 (d, Cortho, Ph,
2J PC ) 10.1 Hz), 120.93 (d, Cipso, Ph, J PC ) 88.1 Hz), 110.21
1
1
3
(dd, dC(P), J PC ) 73.4 Hz, J PC ) 1.9 Hz), 52.45 (s, OMe),
50.42 (s, OMe).
Anal. Calcd for [C63H56ClO8P3Pd]‚0.25CH2Cl2: C, 63.46; H,
4.75. Found: C, 63.28; H, 4.99. MS (FAB+) [m/z, (%)]: 1075
(25%) [(M - ClO4)+], 813 (100%) [(M - ClO4 - PPh3)+]. IR (ν,
cm-1): 1724, 1708 (νCdO). 1H NMR (CD2Cl2, rt): δ (ppm), 7.67-
cis-[P d(C6F5)2(P P h 3){C(CO2Me)-C(P P h 3)(CO2Me)}], 1b.
Complex 1b was prepared following the same experimental
procedure as that described for 1a . (NBu4)2[Pd(µ-Br)(C6F5)2]2
(0.144 g, 0.113 mmol) reacts in dry THF (20 mL) with AgClO4
(0.047 g, 0.23 mmol) and Ph3PdC(CO2Me)-C(CO2Me)dPPh3
(0.150 g, 0.225 mmol) to give 1b as a white solid. Obtained:
0.147 g (59.0% yield). Complex 1b crystallizes as regular block-
shaped colorless crystals by slow vapor diffusion of Et2O into
a CH2Cl2 solution of the crude product.
3
6.98 (m, 40H, Ph + Tol), 6.87 (t, 1H, C6H4, J HH ) 8.4 Hz),
3
6.54 (t, 1H, C6H4, J HH ) 8.4 Hz), 3.95, 3.61 (AB part of an
ABX spin system (X ) 31P), 2H, CH2Pd, J HH ) 16.5 Hz), 2.50
2
(s, 3H, OMe), 2.47 (s, 3H, OMe), 1.95 (s, 3H, Me(tol)), 1.62 (s,
3H, Me(tol)). 31P{1H} NMR (CD2Cl2, rt): δ (ppm), 28.93 (s, br,
P(tol)2), 21.70 (s, br, Pd-PPh3), 11.55 (s, -C(PPh3)). 13C{1H}
NMR (CD2Cl2, rt): δ (ppm), 170.49 (s, CO2), 169.51 (dd, CO2,
J PC ) 10.0 Hz, J PC ) 3.6 Hz), 148.74 (d, C6H4, J PC ) 22.7 Hz),
142.13 (d, C6H4, J PC ) 15.8 Hz), 141.79 (d, C6H4, J PC ) 13.9
Anal. Calcd for [C54H36F10O4P2Pd]: C, 58.58; H, 3.28.
Found: C, 58.35; H, 3.11. MS (FAB+) [m/z, (%)]: 940 (10%)
[(M - C6F5 + H)+], 773 (20%) [(M - 2C6F5 + H+], 677 (15%)
[(M - C6F5 - PPh3)+]. IR (ν, cm-1): 1696 (νCdO). 1H NMR
(CD2Cl2, rt): δ (ppm), 7.69-7.17 (m, 30H, Ph), 3.74 (s, 3H,
OMe), 2.64 (s, 3H, OMe). 31P{1H} NMR (CD2Cl2, rt): δ (ppm),
20.85 (s, Pd-PPh3), 13.42 (s, dC(PPh3)). 19F NMR (CD2Cl2,
rt): δ (ppm), -110.82 (m, 1F, Fortho), -111.66 (m, 1F, Fortho),
-112.17 (m, 1F, Fortho), -116.24 (m, 1F, Fortho), -162.79 (t, 1F,
1
Hz), 136.67-126.56 (m, Ph + C6H4), 123.85 (d, Cipso, Ph, J PC
) 89.6 Hz), 52.43 (s, OMe), 51.43 (s, OMe), 41.29 (s, CH2Pd),
3
3
23.58 (d, Me, J PC ) 13.1 Hz), 22.52 (d, Me, J PC ) 12.9 Hz).
The carbenic carbon PddCR (220-200 ppm) and the ylidic Câ
carbon (about 110 ppm) were not observed despite long
accumulation trials.
[P d (C H 2 C 9 H 6 N -C 8 ,N )(P P h 3 ){C (C O 2 M e )-C (P P h 3 )-
(CO2Me)}](ClO4), 4. Complex 4 was prepared following an
experimental method similar to that described for 2, except
that complex 4 precipitated in THF. [Pd(µ-Cl)(CH2C9H6N-
C8,N)]2 (0.063 g, 0.113 mmol) was reacted with AgClO4 (0.047
g, 0.23 mmol) and with the bis-ylide (0.150 g, 0.225 mmol) in
dry THF to give 4 as a yellow solid insoluble in THF.
Obtained: 0.193 g (90% yield). Complex 4 was recrystallized
from CH2Cl2/Et2O to give yellow crystals of 4‚0.65CH2Cl2. The
amount of CH2Cl2 in the crystals was estimated by integration
of the corresponding resonance in the 1H NMR.
F
para), -163.19 (m, 1F, Fpara), -163.77 (m, 4F, Fmeta). 13C{1H}
NMR (CD2Cl2, rt). This compound was not stable enough in
solution and decomposed during acquisition.
[P t (CH 2C6H 4-o-P (o-t ol)2)(P P h 3){C(CO2Me)-C(P P h 3)-
(CO2Me)}](ClO4), 2. To a suspension of [Pt(µ-Cl)(CH2C6H4-
o-P(o-tol)2)]2 (0.160 g, 0.150 mmol) in dry THF (15 mL) was
added AgClO4 (0.063 g, 0.30 mmol), and the resulting mixture
was stirred for 20 min at room temperature with exclusion of
light. The insoluble AgCl was filtered off, and the solution of
the solvato derivative was reacted with the bis-ylide (0.200 g,
0.300 mmol). The initial deep yellow suspension evolved to a
colorless solution, and some decomposition was evident (pres-
ence of Pt0). After the reaction time (3 h) any insoluble
impurity was removed by filtration and the resulting solution
was evaporated to dryness. Treatment of the residue with Et2O
(15 mL) gave 2 as a pale yellow solid, which was filtered,
washed with Et2O (15 mL), and air-dried. Obtained: 0.248 g
(65% yield).
Anal. Calcd for [C52H44ClNO8P2Pd]‚0.65CH2Cl2: C, 59.10;
H, 4.26; N, 1.31. Found: C, 58.95; H, 4.28; N, 1.40. MS (FAB+)
[m/z, (%)]: 914 (70%) [(M - ClO4)+], 652 (100%) [(M - ClO4 -
PPh3)+]. IR (ν, cm-1): 1722, 1699 (νCdO). 1H NMR (CD2Cl2, rt):
3
4
δ (ppm), 8.53 (dd, 1H, 8mq, J HH ) 5.1 Hz, J HH ) 1.8 Hz),
3
4
8.29 (dd, 1H, 8mq, J HH ) 8.4 Hz, J HH ) 1.8 Hz), 7.87-7.29
(m, 33H, Ph + 8mq), 7.00 (dd, 1H, 8mq, 3J HH ) 8.4 Hz, 4J HH
)
2
5.1 Hz), 4.36 (d, 1H, PdCH2, J HH ) 16.5 Hz), 3.54 (ddd, 1H,
2
3
5
PdCH2, J HH ) 16.5 Hz, J PH ) 10.8 Hz, J PH ) 1.5 Hz), 2.96
(s, 3H, OMe), 2.96 (s, 3H, OMe). 31P{1H} NMR (CD2Cl2, rt): δ
(ppm), 27.32 (s), 26.49 (s). 13C{1H} NMR (CD2Cl2, rt): δ (ppm),
Anal. Calcd for [C63H56ClO8P3Pt]: C, 59.83; H, 4.56.
Found: C, 59.47; H, 4.53. MS (FAB+) [m/z, (%)]: 1165 (10%)
[(M - ClO4)+], 902 (100%) [(M - ClO4 - PPh3)+]. IR (ν, cm-1):
1
171.05 (pseudot, CO2, J PC ) 4.8 Hz), 169.55 (d, CO2, J PC
)
1710, 1691 (νCdO). H NMR (CD2Cl2, rt): δ (ppm), 7.77-6.89
3
11.8 Hz), 157.31 (d, J PC ) 5 Hz), 144.38, 140.42, 139.06, 133.78,
(m, 40H, Ph + Tol), 6.63 (t, 1H, C6H4, J H-H ) 8.0 Hz), 6.29
(dd, 1H, 3J H-H ) 10.0 Hz, 3J H-H ) 8.0 Hz), 3.60, 3.48 (AB part
130.77, 130.46, 127.66, 121.48 (C9H6N), 135.05 (d, Cmeta, Ph,
3J PC ) 10 Hz), 134.43 (d, Cmeta, Ph, J PC ) 14 Hz), 134.33 (s,
3
2
of an ABX spin system (X ) 31P), 2H, CH2Pt, J HH′ ) 16.8
Hz,3J HP ) 6.9 Hz,3J H′P ) 8.4 Hz), 3.26 (s, 3H, OMe), 2.57 (s,
C
para, Ph), 129.38-128.94 (m, Cortho + Cpara, Ph), 123.35 (d, Cipso,
1
3H, OMe), 2.48 (s, 3H, Me), 1.87 (s, 3H, Me). 31P{1H} NMR
Ph, J PC ) 90.6 Hz), 52.73 (s, OMe), 51.58 (s, OMe), 38.55 (t,
CH2Pd, J PC ) 5.1 Hz). The carbenic carbon PddCR (220-200
ppm) and the ylidic Câ carbon (about 110 ppm) were not
observed despite long accumulation trials.
4
(CD2Cl2, rt): δ (ppm), 28.25 (dd, 1P, P(o-tol)2, J PP ) 35.3 Hz,
1
2J PPcis ) 14.8 Hz, J PtP ) 2519 Hz), 18.95 (dd, 1P, Pt-PPh3,
2
1
4J PP ) 5.6 Hz, J PPcis ) 14.8 Hz, J PtP ) 2056 Hz), 15.57 (dd,
4
4
3
1P, -C(PPh3), J PP ) 35.3 Hz, J PP ) 5.6 Hz, J PPt ) 305 Hz).
[P d(NC5H4-o-C6H4)(P P h 3){C(CO2Me)-C(P P h 3)(CO2Me)}]-
(ClO4), 5. Complex 5 was prepared following an experimental
method similar to that described for 2, except that complex 5
precipitated in THF. [Pd(µ-Cl)(NC5H4-o-C6H4)]2 (0.066 g, 0.113
mmol) was reacted with AgClO4 (0.047 g, 0.23 mmol) and with
the bis-ylide (0.150 g, 0.225 mmol) in dry THF to give 5 as a
white solid insoluble in THF. Obtained: 0.157 g (72% yield).
Complex 5 was recrystallized from CH2Cl2/Et2O to give color-
less crystals of 5‚0.5CH2Cl2. The amount of CH2Cl2 in the
crystals was determined by integration of the corresponding
resonance in the 1H NMR.
13C{1H} NMR (CD2Cl2, rt): δ (ppm), 217.21 (dd, PtdC, 2J Ptrans-C
2
3
) 109 Hz, J P-C ) 8.5 Hz), 171.37 (d, CO2, J PC ) 14.4 Hz),
2
167.65 (d, CO2, J PC ) 23.1 Hz), 155.89 (dd, C6H4, J PC ) 33.8
Hz, J PC ) 2.4 Hz), 142.21 (dd, C6H4, J PC ) 34.3 Hz, J PC ) 11.6
Hz), 138.24 (dd, C6H4, J PC ) 60.3 Hz, J PC ) 10.7 Hz), 135.18-
1
125.19 (m, Ph + C6H4), 120.49 (d, Cipso, Ph, J PC ) 88.3 Hz),
1
3
110.77 (dd, dC(P), J PC ) 70.9 Hz, J PC ) 2.7 Hz), 52.49 (s,
2
OMe), 51.14 (s, OMe), 37.09 (d, CH2Pt, J Ptrans-C ) 87.1 Hz,
1J Pt-C ) 548 Hz), 23.53 (d, Me, J PC ) 9.1 Hz), 22.78 (d, Me,
3
3J PC ) 6.4 Hz).

Stabilized Bis-ylides
Organometallics, Vol. 22, No. 5, 2003 1143
Anal. Calcd for [C53H44ClNO8P2Pd]‚0.5CH2Cl2: C, 60.10; H,
4.24; N, 1.31. Found: C, 60.19; H, 4.22; N, 1.46. MS (FAB+)
[m/z, (%)]: 664 (100%) [(M - ClO4 - PPh3)+]. IR (ν, cm-1): 1693
Hz, 2J PPcis ) 21.86 Hz, 1J PtP ) 1509 Hz), 28.20 (dd, P(tol)2, 2J PPcis
) 20.65 Hz, J PtP ) 1392 Hz), 18.78 (dd, PPh3 cis P(tol)2, J PtP
) 989 Hz).
1
1
1
Rea ction of [P d (Cl)(CH2C9H6N-C8,N)(P P h 3)] w ith th e
Bis-ylid e P h 3P dC(CO2Me)-C(CO2Me)dP P h 3. In a way
similar to that described in the preceding paragraphs, [Pd(Cl)-
(CH2C9H6N-C8,N)(PPh3)] (0.123 g, 0.225 mmol) reacted with
AgClO4 (0.047 g, 0.23 mmol) and with the bis-ylide (0.150 g.,
0.225 mmol) in dry THF (20 mL) to give [Pd(CH2C9H6N-C8,N)-
(PPh3)2](ClO4), 8, as a pale yellow solid. Obtained: 0.128 g
(65.2% yield). The evaporation of the ether solution gave a solid
residue, which was identified as a mixture of dimethylfuma-
(νCdO). H NMR (CD2Cl2, rt): δ (ppm), 7.90-7.38 (m, 34H, Ph
3
4
+ C6H4 + NC5H4), 7.10 (td, 1H, Ph-py, J HH ) 8.4 Hz, J HH
)
3
1.2 Hz), 6.96 (t, 1H, Ph-py, J HH ) 7.2 Hz), 6.75 (t, 1H, Ph-py,
3J HH ) 7.2 Hz), 6.51 (td, 1H, Ph-py, J HH ) 6.9 Hz, J HH ) 0.9
Hz), 3.42 (s, 3H, OMe), 2.80 (s, 3H, OMe). 31P{1H} NMR
(CD2Cl2, rt): δ (ppm), 22.34 (d, Pd-PPh3, 4J PP ) 6.7 Hz), 14.78
(d, -C(PPh3)). 13C{1H} NMR (CD2Cl2, rt): δ (ppm), 220.69 (dd,
3
4
PddC, 2J PC ) 14.1 Hz, 2J PC ) 10.2 Hz), 170.49 (d, CO2, 3J PC
)
2
13.5 Hz), 167.98 (d, CO2, J PC ) 23.7 Hz), 163.06, 161.66,
152.10 (d, J PC ) 6.2 Hz), 146.68, 139.48, 134.99, 129.75 (d,
J PC ) 6.6 Hz), 125.83, 124.37 (d, J PC ) 4.6 Hz), 122.29, 119.65
1
rate and OdPPh3 by H and 31P{1H} NMR analysis.
Anal. Calcd for [C46H38ClNO4P2Pd]: C, 63.31; H, 4.39; N,
(C11H8N), 135.75 (d, Cmeta, Ph, 3J PC ) 12.8 Hz), 134.43 (s, Cpara
,
1.60. Found: C, 62.63; H, 4.34; N, 1.56. MS (FAB+) [m/z, (%)]:
Ph), 134.04 (d, Cmeta, Ph, 3J PC ) 10.3 Hz), 131.54 (s, Cpara, Ph),
772 (5%) [(M - ClO4)+], 510 (100%) [(M - ClO4 - PPh3)+].
3
1H NMR (CD2Cl2 rt): δ (ppm), 8.27 (dd, 1H, C9H6N, J HH
)
130.05 (d, Cortho, Ph, 2J PC ) 12.9 Hz), 129.18 (d, Cortho, Ph, 2J PC
4
1
8.4 Hz, J HH ) 1.2 Hz), 7.93 (s, br, 1H, C9H6N), 7.70 (d, 1H,
) 10.1 Hz), 120.72 (d, Cipso, Ph, J PC ) 88.6 Hz), 110.06 (d,
dC(P), J PC ) 77.4 Hz), 52.91 (s, OMe), 51.33 (s, OMe).
3
1
9
C H6N, J HH ) 7.80 Hz), 7.66-7.16 (m, 32H, Ph + C9H6N), 6.87
3
4
(dd, 1H, C9H6N, J HH ) 8.1 Hz, J HH ) 5.7 Hz), 3.27 (s, 2H,
[P d (C13H 8N)(P P h 3){C(CO2Me )-C(P P h 3)(CO2Me )}]-
(ClO4), 6. Complex 6 was prepared following an experimental
method similar to that described for 2, except that complex 6
precipitated in THF. [Pd(µ-Cl)(C13H8N)]2 (0.072 g, 0.113 mmol)
was reacted with AgClO4 (0.047 g, 0.23 mmol) and with the
bis-ylide (0.150 gr, 0.225 mmol) in dry THF to give 6 as a white
solid insoluble in THF. Obtained: 0.090 g (38% yield).
PdCH2). 31P{1H} NMR (CD2Cl2, rt): δ (ppm), 38.58 (d,2J PP
)
37.7 Hz), 20.87 (d).
[P d {t r a n s-C(C6F 5)(CO2Me )-C(P P h 3)(CO2Me )}(t h t )-
(P P h 3)](ClO4), 9. To a solution of [Pd(µ-Cl)(C6F5)(SC4H8)]2
(0.089 g, 0.113 mmol) in dry THF (20 mL) was added AgClO4
(0.047 g, 0.23 mmol). The resulting mixture was stirred for
20 min with exclusion of light and then filtered to remove the
AgCl that precipitated. To the freshly prepared solution of the
solvato derivative the bis-ylide (0.150 g, 0.225 mmol) was
added, resulting in the immediate formation of a yellow
solution. This solution was evaporated to one-third of the
initial volume and stirred for 3 h at room temperature. After
this time a yellow precipitate appeared, which was filtered,
washed with THF (2 mL) and Et2O (15 mL), air-dried, and
identified as 9. Obtained: 0.115 g (45.5% yield). The THF
solution was further evaporated, giving a second crop of 9.
Obtained: 0.046 g (18.2% yield). Total obtained: 0.161 g
(63.7% net yield). The spectroscopic characterization of 9
revealed the presence of two isomers (9a and 9b) in a 9a :9b
) 5:1 molar ratio.
Anal. Calcd for [C55H44ClNO8P2Pd]: C, 62.87; H, 4.22; N,
1.33. Found: C, 62.56; H, 4.13; N, 1.50. MS (FAB+) [m/z, (%)]:
950 (10%) [(M - ClO4)+], 688 (100%) [(M - ClO4 - PPh3)+].
1
IR (ν, cm-1): 1695 (νCdO). H NMR (CD2Cl2, rt): δ (ppm), 8.20
3
4
(dd, 1H, C13H8N, J HH ) 8.1 Hz, J HH ) 1.2 Hz), 7.96-7.91
(m, 6H, Ph), 7.81-7.73 (m, 4H, C13H8N), 7.63-7.55 (m, 9H,
Ph), 7.53-7.44 (m, 15H, Ph), 7.15 (m, 2H, C13H8N), 6.91 (dd,
1H, C13H8N, 3J HH ) 8.1 Hz, 4J HH ) 5.4 Hz), 3.38 (s, 3H, OMe),
2.80 (s, 3H, OMe). 31P{1H} NMR (CD2Cl2, rt): δ (ppm), 22.18
(d, Pd-PPh3,4J PP ) 6.10 Hz), 14.68 (d, -C(PPh3)). 13C{1H}
NMR (CD2Cl2, rt): δ (ppm), 219.67 (dd, PddC, 2J PC ) 13.1 Hz,
3
2J PC ) 9.9 Hz), 170.49 (d, CO2, J PC ) 13.1 Hz), 168.06 (dd,
CO2, 2J PC ) 21.0 Hz, 4J PC ) 1.9 Hz), 161.61, 160.18, 156.02 (d,
J PC ) 5.2 Hz), 151.14 (d, J PC ) 4.8 Hz), 142.15, 138.45, 132.61,
129.90, 128.98 (d, J PC ) 7.2 Hz), 127.71, 124.36, 123.99, 121.51
Anal. Calcd for [C52H44ClF5O8P2PdS]: C, 55.38; H, 3.93; S,
2.84. Found: C, 55.01; H, 3.99; N, 2.99. MS (FAB+) [m/z, (%)]:
(C13H8N), 135.81 (d, Cmeta, Ph, 3J PC ) 12.8 Hz), 134.49 (d, Cpara
,
939 (10%) [(M - ClO4 - SC4H8)+], 677 (40%) [(M - ClO4
SC4H8 - PPh3)+], 571 (100%) [(M - Pd - ClO4 - SC4H8
-
-
Ph, 4J PC ) 2.6 Hz), 134.03 (d, Cmeta, Ph, 3J PC ) 10.3 Hz), 131.58
2
(s, Cpara, Ph), 130.11 (d, Cortho, Ph, J PC ) 12.9 Hz), 129.21 (d,
PPh3)+ ≡ (C6F5C(CO2Me)C(CO2Me)PPh3)+]. IR (ν, cm-1): 1695
2
1
C
ortho, Ph, J PC ) 9.8 Hz), 120.79 (d, Cipso, Ph, J PC ) 88.7 Hz),
1 3
1
(νCdO), 1244 (SC4H8), 982, 922 (C6F5). H NMR (CDCl3, rt): δ
110.14 (dd, dC(P), J PC ) 71.2 Hz, J PC ) 3.8 Hz), 52.95 (s,
OMe), 51.38 (s, OMe).
(ppm), 7.68-7.33 (m, Ph), 3.44 (s, OMe, 9b), 2.89 (s, OMe, 9a ),
2.83 (s, OMe, 9a ), 2.80 (s, OMe, 9b), 2.64 (m, SC4H8, both),
2.43 (m, SC4H8, both), 1.57 (s, SC4H8, both). 31P{1H} NMR
(CD2Cl2, rt): δ (ppm), 29.08 (d, PA, 9b,3J PP ) 18.2 Hz), 28.56
Rea ction of [P t(Cl)(CH2C6H4-o-P (o-tol)2)(P P h 3)] w ith
th e Bis-ylid e P h 3P dC(CO2Me)-C(CO2Me)dP P h 3. To a
solution of [Pt(Cl)(CH2C6H4-o-P(o-tol)2)(PPh3)] (0.178 g, 0.225
mmol) in dry THF (20 mL) was added AgClO4 (0.047 g, 0.23
mmol), and the resulting mixture was stirred for 20 min at
room temperature with exclusion of light. The AgCl that
precipitated was filtered off, and the resulting solution of the
solvato derivative was treated with the bis-ylide (0.150 g, 0.225
mmol). The initial yellow suspension gradually dissolved
(about 30 min). This solution was evaporated to small vol-
ume (≈5 mL), and by Et2O (20 mL) addition the complex
[Pt(CH2C6H4-o-P(o-tol)2)(PPh3)2](ClO4), 7, was obtained as a
yellow solid. Obtained: 0.235 g (93% yield). The evaporation
of the ether solution gave a solid residue, which was iden-
tified as a mixture of dimethylfumarate and OdPPh3 by 1H
and 31P{1H} NMR analysis.
5
(s, PA, 9a ), 25.92 (d, PB, 9a , J PF ) 26 Hz), 23.18 (d, PB, 9b).
19F NMR (CD2Cl2, ta): δ (ppm), -131.35 (d, Fo, 9b, J FF ) 22.6
Hz), -134.04 (d, Fo, 9a , J FF ) 22.6 Hz), -134.25 (t, Fo, 9a , J FF
≈ J PF ) 26 Hz), -136.29 (d, Fo, 9b, J FF ) 25 Hz), -152.97 (t,
Fp, 9b, J FF ) 22.6 Hz), -154.84 (t, Fp, 9a , J FF ) 22.6 Hz),
-161.32 (t, Fm, 9b), -161.83 (t, Fm, 9a ), -162.57 (t, Fm, 9b),
-162.77 (t, Fm, 9a ).
[P d {tr a n s-C(C6F 5)(CO2Me)-C(P P h 3)(CO2Me)}(P P h 3)2]-
(ClO4), 10. Complex 10 was prepared following the same
experimental method as that described for 9, except that the
product was precipitated with Et2O after evaporation to
dryness of the THF solution. [Pd(µ-Cl)(C6F5)(PPh3)]2 (0.128 g,
0.113 mmol) was reacted in dry THF (10 mL) with AgClO4
(0.047 g, 0.23 mmol) and the bis-ylide (0.150 g, 0.225 mmol)
to give 10 as a pale orange solid. Obtained: 0.158 g (53.9%
yield).
Anal. Calcd for [C57H50ClO4P3Pt]: C, 60.99; H, 4.49.
Found: C, 60.78; H, 4.44. MS (FAB+) [m/z, (%)]: 1022 (15%)
[(M - ClO4)+], 760 (100%) [(M - PPh3 - ClO4)+]. 1H NMR
(CD2Cl2, rt): δ (ppm), 7.47-6.88 (m, 41H, C6H4 + Tol + Ph),
Anal. Calcd for [C66H51ClF5O8P3Pd]: C, 60.89; H, 3.95.
Found: C, 60.54; H, 3.91. IR (ν, cm-1): 1698, 1677 (νCdO), 985,
3
4
6.62 (dd, 1H, C6H4, J HH ) 7.5 Hz, J HH ) 2.4 Hz), 3.23 (s, br,
2H, PtCH2, 2J PtH ) 63 Hz), 2.29 (s, 6H, Me). 31P{1H} NMR (CD2-
Cl2, rt): δ (ppm), 43.05 (dd, PPh3 trans P(tol)2, 2J PPtrans ) 364.5
914 (C6F5). MS (FAB+) [m/z, (%)]: 939 (10%) [(M - ClO4 -
PPh3)+], 677 (25%) [(M - ClO4 - 2PPh3)+], 571 (100%) [(M -
1
Pd - ClO4 - 2PPh3)+ ≡ (C6F5C(CO2Me)C(CO2Me)PPh3)+]. H

1144 Organometallics, Vol. 22, No. 5, 2003
Falvello et al.
NMR (CDCl3, rt): δ (ppm), 7.79-7.09 (m, 45H, Ph), 2.73 (s,
3H, Ph), 7.50-7.44 (m, 6H, Ph), 3.83 (s, 3H, OMe), 3.27 (s,
3H, OMe). 31P{1H} NMR (CD2Cl2, rt): δ (ppm), 16.60. 13C{1H}
3H, OMe), 2.65 (s, 3H, OMe). 31P{1H} NMR (CD2Cl2, rt): δ
2
2
(ppm), 29.97 (d, PA,3J PAPB ) 17.5 Hz), 23.22 (dd, PB, J PBPC
)
NMR (CD2Cl2, rt): δ (ppm), 184.38 (d, CO, J PC ) 6.2 Hz),
5
26.0 Hz), 21.44 (t, PC, J PCF
≈
2J PBPC ) 26 Hz). 19F NMR
(CD2Cl2, rt): δ (ppm), -129.99 (d, Fo, J FF ) 17 Hz), -131.30
(t, Fo, J FF ≈ J PF ) 26 Hz), -155.95 (t, Fp, J FF ) 19 Hz), -161.35
(t, Fm), -163.37 (t, Fm).
167.79 (d, CO2, J PC ) 14.8 Hz), 167.55 (d, CO2, J PC ) 13.2 Hz),
3
4
133.64 (d, Cmeta, Ph, J PC ) 10.2 Hz), 132.54 (d, Cpara, Ph, J PC
) 2.7 Hz), 128.79 (d, Cortho, Ph, 2J PC ) 12.8 Hz), 123.92 (d, Cipso
,
Ph, 1J PC ) 93.3 Hz), 68.04 (d, PdC, 1J PC ) 111.2 Hz), 51.89 (s,
OMe), 50.34 (s, OMe).
Rea ctivity of th e Mixtu r e 9a /9b. NMR Exp er im en ts.
(a) To a solution of 9 (25 mg, 0.022 mmol) in CDCl3 (0.4 mL)
was added PPh3 (6 mg, 0.02 mmol). The initial yellow color of
9 changed in a few seconds to pale orange. The 1H, 19F, and
31P{1H} NMR spectra were registered 5 min after mixture
(time for locking and shimming). The NMR spectra showed
the presence of a mixture 9/PPh3/10 in a 0.25:0.5:1 molar ratio.
(b) To a solution of 9 (25 mg, 0.022 mmol) in CD2Cl2 (0.4 mL)
was added bis(diphenylphosphino)methane (dppm, 9 mg, 0.02
mmol). The yellow color of 9 dissappeared instantaneously,
giving a colorless solution. The NMR spectra of this solution
showed, exclusively, signals corresponding to 11a . (c) To a
solution of 9 (25 mg, 0.022 mmol) in CD2Cl2 (0.4 mL) was added
bis(diphenylphosphino)ethane (dppe, 9 mg, 0.02 mmol). A
colorless solution was obtained in a few seconds. The NMR
spectra of this solution showed, exclusively, signals corre-
sponding to 11b.
Cr yst a l St r u ct u r e Det er m in a t ion of Com p lex 1a ‚
CH2Cl2. Crystals of complex 1a ‚CH2Cl2 of adequate quality
for X-ray measurements were grown by slow vapor condensa-
tion of Et2O over a CH2Cl2 solution of crude 1a at room
temperature. A single crystal of dimensions 0.23 × 0.11 × 0.10
mm was mounted at the end of a quartz fiber in a random
orientation and covered with epoxy.
Da ta Collection . Data collection was performed at room
temperature on a Bruker Smart CCD diffractometer using
graphite-monochromated Mo KR radiation (λ ) 0.71073 Å)
with a nominal crystal-to-detector distance of 4.0 cm. A
hemisphere of data was collected based on three ω-scan runs
(starting ω ) -30°) at values φ ) 0°, 90°, and 180° with the
detector at 2θ ) 30°. For each of these runs, frames (606, 435,
and 230, respectively) were collected at 0.3° intervals and 30
s per frame. The diffraction frames were integrated using the
program SAINT,33 and the integrated intensities were cor-
rected for absorption with SADABS.34
Str u ctu r e Solu tion a n d Refin em en t. The structure was
solved and developed by Patterson and Fourier methods.35 All
non-hydrogen atoms were refined with anisotropic displace-
ment parameters. The hydrogen atoms were placed in ideal-
ized positions and treated as riding atoms. Each hydrogen
atom was assigned an isotropic displacement parameter equal
to 1.2 times the equivalent isotropic displacement parameter
of its parent atom. The two interstitial dichloromethane
molecules are disordered, each in two equally populated
congeners. The structures were refined to Fo2, and all reflec-
tions were used in the least-squares calculations.36 Crystal-
lographic calculations were done on an AlphaStation (OPEN/
VMS V6.2).
Sp ect r oscop ic Ch a r a ct er iza t ion of 11a . 1H NMR
(CD2Cl2, rt): δ (ppm), 7.81-6.63 (m, Ph), 4.20 (m, 1H, PCH2P),
3.34 (m, 1H, PCH2P), 2.82 (s, 3H, OMe), 2.50 (s, 3H, OMe).
31P{1H} NMR (CD2Cl2, rt): δ (ppm), 26.97 (d, PA,3J PAPC ) 16.4
2
Hz), 24.27 (t, PB, 5J PBF ≈ J PBPC ) 26 Hz), 17.91 (m, PC), -21.70
2
(d, PD, J PDPC ) 23.1 Hz). 19F NMR (CD2Cl2, ta): δ (ppm),
-131.19 (s, br, Fo), -132.32 (t, Fo, J FF ≈ J PF ) 26 Hz), -156.61
(t, Fp, J FF ) 23 Hz), -161.33 (t, Fm), -164.04 (t, Fm).
Sp ect r oscop ic Ch a r a ct er iza t ion of 11b . 1H NMR
(CD2Cl2, rt): δ (ppm), 8.01-6.44 (m, Ph), 2.64 (s, 3H, OMe),
2.46 (s, 3H, OMe) 2.12-1.80 (m, PCH2CH2P). 31P{1H} NMR
(CD2Cl2, rt): δ (ppm), 27.48 (d, PA,3J PAPC ) 16.1 Hz), 23.75 (t,
2
PB, 5J PBF ≈ J PBPC ) 30 Hz), 19.77 (td, PC), -14.86 (d, PD, 3J PDPC
) 30.3 Hz). 19F NMR (CD2Cl2, ta): δ (ppm), -131.16 (s, br,
Fo), -132.29 (t, Fo, J FF ≈ J PF ) 30 Hz), -156.65 (t, Fp, J FF
)
23 Hz), -161.44 (t, Fm), -164.07 (t, Fm).
Rea ctivity of Hg(OAc)2 w ith th e Bis-ylid e. To a suspen-
sion of Hg(OAc)2 (0.072 g, 0.23 mmol) in dry THF (20 mL) was
added the bis-ylide (0.150 g, 0.225 mmol). The resulting
suspension was stirred at room temperature for 24 h. The
initial yellow suspension changed gradually to gray, and, after
the reaction period, the suspension was filtered. The resulting
gray solid was recrystallized from CH2Cl2/Et2O, giving a white
solid, characterized as [Hg(OAc)2(PPh3)], 12. Obtained: 0.052
g, (40% yield based on Hg). The yellowish THF solution was
evaporated to dryness and the oily residue treated with Et2O
(10 mL), giving a yellow solid (0.120 g) characterized by NMR
as a mixture of the starting compounds. The ether solution
was allowed to stand for 24 h at room temperature. During
this time, colorless crystals of the ylide 13 were formed, which
were collected and air-dried. Obtained: 0.043 g, (45% yield
based on bis-ylide).
Ack n ow led gm en t. Funding by the Direccio´n Gen-
eral de Investigacio´n Cient´ıfica y Te´cnica (DGICYT)
(Spain, Projects PB98-1595-C02-01, PB98-1044, and
PB98-1593) and Fundacio´ Caixa Castello´-Bancaixa
through Project P1B98-07 is gratefully acknowledged,
and we thank Prof. J . Fornie´s for invaluable logistical
support. We are most indebted to the “Servei Central
d’Instrumentacio´ Cient´ıfica” (SCIC) of the University
J aume I for the use of X-ray facilities.
Su p p or tin g In for m a tion Ava ila ble: A drawing of com-
plex 1a ‚CH2Cl2. Tables giving complete data collection param-
eters, atomic coordinates, complete bond distances and angles,
and thermal parameters for 1a ‚CH2Cl2. This material is
available free of charge via the Internet at http://pubs.acs.org.
Characterization of 12. Anal. Calcd for [C22H21HgO4P]: C,
45.48; H, 3.64. Found: C, 45.34; H, 3.55. MS (FAB+) [m/z,
(%)]: 522 (100%) [(M - OAc)+]. IR (ν, cm-1): 1582 (νCO, OAc),
530, 505, 495 (PPh3). 1H NMR (CD2Cl2, rt): δ (ppm), 7.68-
7.54 (m, 15 H, Ph), 1.83 (s, 6H, OMe). 31P{1H} NMR (CD2Cl2,
OM020467D
(33) SAINT Version 5.0; Bruker Analytical X-ray Systems: Madison,
WI, 1995.
(34) Sheldrick, G. M. SADABS: Empirical absorption correction
program; Go¨ttingen University, 1996.
1
rt): δ (ppm), 32.65 (s, J HgP ) 8389 Hz).
Characterization of 13. Anal. Calcd for [C24H21O5P]: C,
68.57; H, 5.03. Found: C, 68.31; H, 4.90. MS (FAB+) [m/z,
(%)]: 421 (10%) [(M + H)+], 361 (100%) [(M - CO2Me)+]. IR
(ν, cm-1): 1740 (νCO), 1671 (νCOOMe), 1564 (νPdC-COOMe). 1H NMR
(CD2Cl2, rt): δ (ppm), 7.69-7.57 (m, 6H, Ph), 7.56-7.54 (m,
(35) Sheldrick, G. M. SHELXS-86, Acta Crystallogr. 1990, A46, 467.
(36) Sheldrick, G. M. SHELXL-97: FORTRAN program for the
refinement of crystal structures from diffraction data; Go¨ttingen
University, 1997. Molecular graphics were done using the commercial
package SHELXTL-PLUS, Release 5.05/V; Siemens Analytical X-ray
Instruments, Inc.: Madison, WI, 1996.