Nitrogen- Vs Carbon-Coordination of the α-Cyano-Stabilized Phosphorus Ylide Ph3P=C(H)CN, X-ray Crystal Structure of {Pd(dmba)[P(OMe)3] [N≡C - C(H)=PPh3]}(ClO4)

Article abstract of DOI:10.1021/ic960904e

The reaction of the solvated complexes [Pd(CN)(PR'₃(THF)](ClO₄) [CN = 2-((dimethylamino)methyl)phenyl-C¹,N or dmba, 2-(1-(R)-(dimethylamino)ethyl)phenyl-C¹,N or (R)-dmphea; PR'₃ = PPh₃, P(O

Full text of DOI:10.1021/ic960904e

1136
Inorg. Chem. 1997, 36, 1136-1142
Nitrogen- Ws Carbon-Coordination of the r-Cyano-Stabilized Phosphorus Ylide
Ph3PdC(H)CN. X-ray Crystal Structure of
{Pd(dmba)[P(OMe)3][NtCsC(H)dPPh3]}(ClO4)
Larry R. Falvello, Susana Ferna´ndez, Rafael Navarro,* and Esteban P. Urriolabeitia
Departamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales de Arago´n,
Universidad de Zaragoza-Consejo Superior de Investigaciones Cient´ıficas, 50009 Zaragoza, Spain
ReceiVed August 1, 1996X
The reaction of the solvated complexes [Pd(CkN)(PR′3)(THF)](ClO4) [CkN = 2-((dimethylamino)methyl)phenyl-
C1,N or dmba, 2-(1-(R)-(dimethylamino)ethyl)phenyl-C1,N or (R)-dmphea; PR′3 ) PPh3, P(OMe)3] with a
stoichiometric amount of Ph3PdC(H)CN (CPPY) (1:1 molar ratio), in THF at low temperature, gives the cationic
derivatives {Pd(CkN)(PR′3)[NtCsC(H)dPPh3]}(ClO4), 4-6, in which the ylide ligand is N-coordinated to the
PdII center and trans to the ortho-metalated C6H4 group, in an “end-on nitrile” coordination mode that is
unprecedented for this ylide. The reaction of [Pd(CkN)(NCMe)2](ClO4) (CkN = dmba, (R)-dmphea) with
Ph3PdC(H)CN (1:2 molar ratio) gives the bis(ylide) complexes [Pd(CkN)(Ph3PCHCN)2](ClO4) (7, 8) in which
one of the ylides is C-coordinated (trans to the NMe2 group) and the other one is N-bonded (and trans to the
C6H4 group). Either by reaction of [Pd(CkN)(NCMe)2](ClO4) with Ph3PdC(H)CN (1:1 molar ratio) or by reaction
of the bis(ylide) complexes [Pd(CkN)(Ph3PCHCN)2](ClO4) with [Pd(CkN)(NCMe)2](ClO4) (1:1 molar ratio),
very insoluble materials of stoichiometry [Pd(CkN)(Ph3PCHCN)(ClO4)] (9, 10) are obtained, which appear to be
dinuclear derivatives with the ylide acting as a C,N-bridging group, [(CkN)Pd(µ-C,N-Ph3PCHCN)2Pd(CkN)]-
(ClO4)2. At the same time, this ylide is shown to be sufficiently nucleophilic to promote the bridge-splitting of
the dinuclear [Pd(µ-Cl)(CkN)]2 complexes, giving the mononuclear derivatives [PdCl(CkN)(Ph3PCHCN)] (11,
12) as a mixture of two isomers; in one of them, the ylide acts as a C-donor while in the other it acts as an
N-donor. IR and NMR spectroscopies allow the unambiguous characterization of all of these products, and the
X-ray crystal structure of {Pd(dmba)[P(OMe)3][NtCsC(H)dPPh3]}(ClO4) (5) is reported. Complex 5 crystallizes
in the monoclinic system, space group P21/c, a ) 12.5690(10) Å, b ) 17.857(2) Å, c ) 14.729(2) Å, â )
92.560(10)°, Z ) 4, V ) 3302.5(6) Å3, 4881 reflections with I > 2σ(I) for the refinement of 423 parameters and
30 restraints, R1 ) 0.0384, wR2 ) 0.0961, and GOF ) 1.044.
Introduction
ylide Ph3PdC(H)CN (CPPY). In addition to the “usual”
C-coordination (form A, Figure 1) one could expect for this
ylide an end-on, N-linear coordination (as a nitrile, form B), an
N-angular coordination (form C) or even a side-on π-coordina-
tion (form D). These coordination modes could be rationalized
taking into account the electron delocalization through the
resonance forms a-c shown in Figure 1.
We have studied the reactivity of Ph3PdC(H)CN (CPPY)
toward several C,N-cyclometalated complexes of PdII of stoi-
chiometry [Pd(CkN)(L)(L′)](ClO4) (CkN ) dmba, (R)-dmphea;
L) PPh3, P(OMe)3, L′ ) THF; L ) L′ ) NCMe) and [Pd(µ-
Cl)(CkN)]2 (CkN = dmba, (R)-dmphea). This paper deals with
the results obtained in this study and shows clearly the expected,
but to date not reported, ambidentate character of the CPPY
ylide.
The carbonyl-stabilized phosphorus ylides R3PdC(R′)COR′′
(R, R′, R′′ ) alkyl, aryl, alkoxy, etc) have been shown to be
very versatile ligands due to their ambidentate character, in
addition to their applicability in organic synthesis.1
In spite of the wide field of applications of the carbonyl-
stabilized ylides, other R-stabilized ylides, such as the R-cyano-
stabilized phosphorus ylide Ph3PdC(H)CN, have received much
less attention. In fact, for the latter, very few reports on its
ability to act as a ligand2 or as a synthetic tool in organic
chemistry3 have been published.
As part of our current research in the R-stabilized phosphorus
ylides,4 we have focused attention on the R-cyano-stabilized
X Abstract published in AdVance ACS Abstracts, February 1, 1997.
(1) Johnson, A. W.; Kaska, W. C.; Starzewski, K. A. O.; Dixon, D. A.
Ylides and Imines of Phosphorus; John Wiley & Sons, Inc.: New
York, 1993; Chapter 14 and references given therein.
Results and Discussion
(2) (a) Burmeister, J. L.; Silver, J. L.; Weleski, E. T.; Schweizer, E. E.;
Kopay, C. M. Synth. React. Inorg. Met.-Org. Chem. 1973, 3, 339. (b)
Nishiyama, H.; Itoh, K.; Ishii, Y. J. Organomet. Chem. 1975, 87, 129.
(c) Weleski, E. T.; Silver, J. L.; Jansson, M. D.; Burmeister, J. L. J.
Organomet. Chem. 1975, 102, 365.
(3) (a) Trippett, S.; Walker, D. M. J. Chem. Soc. 1959, 3874. (b) Pappas,
J. J.; Gancher, E. J. Org. Chem. 1966, 1287. (c) Pappas, J. J.; Gancher,
E. J. Org. Chem. 1966, 3877. (d) Bestmann, H. J.; Schmidt, M.
Tetrahedron Lett. 1987, 28, 2111. (e) Bestmann, H. J.; Schmidt, M.
Angew. Chem., Int. Ed. Engl. 1987, 26, 79. (f) Pandolfo, L.; Facchin,
G.; Bertani, R.; Ganis, P.; Valle, G. Angew. Chem., Int. Ed. Engl.
1994, 33, 576.
Reactions of [Pd(CkN)(PR′3)(THF)](ClO4) with CPPY.
The starting solvated complexes [Pd(CkN)(PR′3)(THF)](ClO4)
[CkN = dmba, (R)-dmphea; PR′3 ) PPh3, P(OMe)3] were
prepared by reaction of the corresponding chloride derivatives
[PdCl(CkN)(PR′3)] (2-2′′, see Scheme 1) with AgClO4 (1:1
molar ratio) in THF at room temperature. Once the AgCl had
been eliminated by filtration, the freshly prepared solution of
[Pd(CkN)(PR′3)(THF)](ClO4) was cooled to 0 °C and allowed
to react with CPPY (1:1 molar ratio), giving white solids of
stoichiometry [Pd(CkN)(PR′3)(CPPY)](ClO4) [CkN = dmba,
PR′3 ) PPh3, 4, P(OMe)3, 5; CkN= (R)-dmphea, PR′3 ) PPh3,
(4) Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Urriolabeitia, E. P. Inorg.
Chem. 1996, 35, 3064 and references given therein.
S0020-1669(96)00904-4 CCC: $14.00 © 1997 American Chemical Society

Nitrogen vs Carbon Coordination
Inorganic Chemistry, Vol. 36, No. 6, 1997 1137
different from those found2b in [Pd(µ-Cl)Cl(CPPY)]2 (for which
C-coordination has been proposed). Moreover, the 31P{1H}
NMR spectra (Table 2) show the ylidic phosphorus resonance
in a very short range of frequencies (24.17-24.68 ppm) and
very close to that of the free ylide (23.75 ppm), and the 13C-
{1H} NMR spectra (Table 2) show the resonance attributed to
the ylidic carbon atom as a doublet around 1.5 ppm with a
1
coupling constant JP-C of 135 Hz, with values very similars
to those found in the free ylide (-2.17 ppm/136 Hz). All these
facts imply that no important structural and electronic changes
have occured in the neighborhood of the ylidic fragment
-C(H)dPPh3 during the coordination process, thus strongly
suggesting end-on N-coordination of the ylide. The ylide could
be seen, then, as a functionalized nitrile [Pd]rΝtCsR, -R
being the ylidic group -C(H)dPPh3.
The PR′3-trans-to-NMe2 ligand arrangement in the starting
products9 is preserved, after chlorine abstraction and ylide
coordination, in complexes 4-6, as can be inferred from the
4
small, but significant, coupling constants JP-H (ranging from
1.8 to 3.9 Hz) of the NMe2 and the CH2N protons with the
phosphorus atom.10,11 Thus, an N(ylide)-trans-to-C(ortho-
metalated) ligand arrangement results, as has been depicted in
Scheme 1, the reaction occurring with retention of the config-
uration at the palladium atom.
The crystal structure of {Pd(dmba)[P(OMe)3][NtCsC-
(H)dPPh3]}(ClO4), 5, provides further characterization.
A
drawing of the organometallic cationic fragment is shown in
Figure 2, and selected bond distances and angles are collected
in Table 4.
The palladium atom is located in a slightly distorted square-
planar environment, surrounded by the C and N atoms of the
ortho-metalated dmba ligand, the P atom of the phosphite ligand
and the N atom of the ylide ligand, with the latter showing its
end-on N-coordination.
Figure 1. (a-c) Resonance forms of the CPPY ylide; (A-D) different
coordination modes expected for the CPPY ylide as ligand.
The structural parameters of the dmba4,10,11 and P(OMe)3
ligands12,13 are similar to those found in other complexes
containing these ligands. The Pd(1)-N(2) bond distance [2.076
(3) Å] is similar to that found in other palladium-nitrile
complexes,14 and the N(2)-C(13) bond distance [1.156 (5) Å]
is fairly typical of nitriles.14,15 The C(13)-C(14) bond distance
[1.379 (5) Å] is shorter than a C(sp2)-C(sp1) bond distance
[1.431 Å]15 and is similar to other C-C bond distances found
in ylides for which resonance delocalization has been sug-
gested: 1.407(8) and 1.399(8) Å for Ph3PdC(H)sCOPh16 and
1.366(4) Å for {Pd(dmba)(py)[OC(Me)dC(H)PPh3]}(ClO4).4
This fact implies a partial multiple bond character for this bond.
As was inferred from the NMR data in solution, the ylide
fragment -C(H)dPPh3 remains almost unaltered; the P(2)-
C(14) bond distance [1.710 (4) Å] is similar, within experimental
error, to those determined for the free ylide Ph3PdCH2 [1.697-
(3), 1.688(3) Å]17 or other free keto stabilized ylides, such as
6; see Scheme 1), as characterized by their elemental analyses
and mass spectra (see Experimental Section).
The IR spectra of 4-6 show a sharp, very strong absorption
in the 2150-2185 cm-1 range (see Table 1) which corresponds
to the ν(CN) absorption of the nitrile. This absorption is shifted
to higher energies with respect to that in the free ylide (2136
cm-1),2c thus giving a positive ∆ν value (∆ν ) νcomplex - νfree
ylide). The observation of this positive ∆ν value implies that
the ylide cannot be coordinated in forms C or D (Figure 1),
since in these forms a negative ∆ν value would be expected.
Coordination in form C implies a major contribution of the
resonance form c and a decrease in the CN multiple bond
character; furthermore, a shift to lower frequencies of the ν-
(CN) absorption has been considered characteristic of the side-
on coordinated nitriles (form D).5,6 Both forms A and B in
Figure 1 are in accord with the observed positive ∆ν value.
Coordination in form A implies a major contribution of the
resonance form b and an increase in the ν(CN) frequency2b,c
with respect to the free ylide, and it is sensible, furthermore, to
assume that the end-on form B would give spectroscopic
behavior similar to that usually observed for end-on coordinated
nitriles,5-7 that is, an increase in the ν(CN) frequency.
(8) Bestmann, H. J.; Snyder, J. P. J. Am. Chem. Soc. 1967, 89, 3936.
(9) Deeming, A. J.; Rothwell, I. P.; Hursthouse, M. B.; New, L. J. Chem.
Soc., Dalton Trans. 1978, 1490.
(10) Braunstein, P.; Matt, D.; Dusausoy, Y.; Fischer, J.; Mitschler, A.;
Ricard, L. J. Am. Chem. Soc. 1981, 103, 5115.
(11) Braunstein, P.; Matt, D.; Dusausoy, Y.; Fischer, J. Organometallics
1983, 2, 1410.
(12) Bao, Q.-B.; Geib, S. J.; Rheingold, A. L.; Brill, T. B. Inorg. Chem.
1987, 26, 3453.
(13) Orpen, A. G.; Brammer, L.; Allen, F. H.; Kennard, O.; Watson, D.
G.; Taylor, R. J. Chem. Soc., Dalton Trans. 1989, S1.
(14) Olmstead, M. M.; Guimerans, R. R.; Farr, J. P.; Balch, A. L. Inorg.
Chim. Acta 1983, 75, 199.
(15) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen, A.
G.; Taylor, R. J. Chem. Soc., Perkin Trans. 2 1987, S1.
(16) Kalyanasundari, M.; Panchanatheswaran, K.; Parthasarathi, V.; Rob-
inson, W. T.; Wen, H. Acta Crystallogr. 1994, C50, 1738.
(17) Schmidbaur, H.; Jeong, J.; Schier, A.; Graf, W.; Wilkinson, D. L.;
Mu¨ller, G.; Kru¨ger, C. New J. Chem. 1989, 13, 341.
The 1H NMR spectra of 4-6 show, in addition to the
expected resonances for the dmba (or the (R)-dmphea) and PPh3
[or P(OMe)3] ligands (see Experimental Section), a doublet
resonance at high field (ranging from 1.2 to 2.03 ppm, see Table
2) with a coupling constant of 2JP-H around 5 Hz, and attributed
to the methine PCH proton. These values of δ(CH) and 2JP-H
are very close to those reported8 for the free ylide and are very
(5) Clark, H. C.; Manzer, L. E. Inorg. Chem. 1971, 10, 2699.
(6) Storhoff, B. N.; Lewis, H. C. Coord. Chem. ReV. 1977, 23, 1.
(7) Wada, M.; Shimohigashi, T. Inorg. Chem. 1976, 15, 954.

1138 Inorganic Chemistry, Vol. 36, No. 6, 1997
Falvello et al.
Scheme 1
Table 1. Relevant IR Absorptions (ν, cm-1) for Complexes 4-12
complex
ν(CN)
∆νa
4
2158
2181
2166
2174
2172
2224
2229
2178
2187
2136
+22
+45
+30
+38
+36
+88
+93
+42
+51
5
6
7
8
9
10
11
12
CPPY
a ∆ν ) ν(CN)complex - ν(CN)free ylide
.
n
Table 2. Relevant NMR Data (δ, ppm; J, Hz) for Complexes
4-12
Figure 2. Thermal ellipsoid plot of the {Pd(dmba)[P(OMe)3][NCsC-
(H)dPPh3]}+ cation. Ph groups (except Cipso) and H atoms are omitted
for clarity. Atoms are drawn at the 50% probability level.
complex δ(CH)
2JP-H
δ(P)
24.17
24.68
24.24
δ(CH)
1.49
1.64
1.53
1.88/-1.25 136/46
2.20/1.94 136/136
1JP-C
4 (N)a
5 (N)a
6 (N)a
1.24
2.03
1.26
5.4
5.2
5.4
136
135
136
Table 3. Crystal Data for 5
formula
cryst syst
C32H37ClN2O7P2Pd V, Å3
3302.5 (6)
1.539
7 (N/C)a 1.45/3.05 6.0/13.8 24.35/26.80
monoclinic
d
calc, g/cm3
8 (N)a
1.41/1.38 5.9/5.9 24.28/24.52
3.11/3.08 14.0/13.3 26.62/27.25 -1.48/-1.67 46/46
space group P21/c
cryst size, mm
0.40 × 0.35
× 0.30
0.789
(C)a
11a (C)a 4.37
11b (N)a 1.92
14.3
6.5
28.07
23.66
-6.04
1.94
46
137
45
fw
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
Z
765.43
12.5690(10)
17.857(2)
14.729(2)
90.0
92.560(10)
90.0
4
µ, mm-1
no of unique rflcns
5790
12a (C)a 4.58/4.29 14.0/14.0 28.31/27.94 -7.07b
no of rflcns with I > 2σ(I) 4881
12b (N)a 1.90
CPPY
1.61c
6.5
23.62
1.89
137
no of variables/restraints 423/30
7.8c
23.75d
-2.17d
136d
R1a
0.0384
0.0961
1.044
wR2a
a N ) N-coordinated isomer; C ) C-coordinated isomer, b Both
GOFa
isomers. c Determined by us at 203 K in CD2Cl2. Values for 1H RMN
max. shift / σ
-0.087
-60 °C
in ref 8 are δ ) 1.62 ppm, JPCH
temperature.
) 7.5 Hz. d CDCl3, room
F(000)
T, °C
1568
-123(2)
res electron density, e/Å3 0.864
λ, Å
0.71073
2
2
a R1 ) ∑||Fo| - |Fc||/∑|Fo|; wR2 ) [∑w(Fo - Fc2)2/∑w(Fo )2]1/2
.
Ph3PdC(H)COPh [1.716(5), 1.725(4) Å]16 and is notably
shorter than the other P-C distances of the ylide in 5 [average:
1.802(4) Å].
The N-coordinated ylide shows an almost linear coordination,
typical of end-on coordinated nitriles, as can be seen from the
2
GOF ) [∑w(Fo - Fc2)2/(nobservns - nparams)]1/2
.
bond angles Pd(1)-N(2)-C(13) [177.1 (3)°] and N(2)-C(13)-
C(14) [177.7 (4)°]. The environment at C(14) is planar [∑angles
) 360.0°] and that of the P(2) is tetrahedral (average of
angles: 109.44°).
The most striking feature of 4-6 is the selective N-
coordination of the ylide, and these results could be easily
explained by invoking the relative hardness and softness of the
different donor atoms19 bonded to palladium and the antisym-
(18) The reaction of the solvated complexes [Pd(CkN)(PPh3)(THF)](ClO4)
(CkN = dmba, (R)-dmphea) with the ylides Ph3PdC(H)COR (R )
Me, Ph, OMe) gives products of stoichiometry [Pd(CkN)(PPh3)(ylide)]-
(ClO4) in which the ylide acts selectively as an O-donor ligand.
Falvello, L. R.; Ferna´ndez, S.; Navarro, R.; Pascual, I.; Urriolabeitia,
E. P. J. Chem. Soc., Dalton Trans., in press.

Nitrogen vs Carbon Coordination
Inorganic Chemistry, Vol. 36, No. 6, 1997 1139
Table 4. Selected Bond Distances (Å) and Angles (deg) for 5
we have the simultaneous presence of a C-coordinated ylide
and another one N-coordinated to the same metal center. Other
redistribution products, such as those containing both ylides
C-coordinated or both N-coordinated, are not observed. In
addition, of the two possible geometric isomers (C-trans-to-
NMe2 or N-trans-to-NMe2), only one is observed. The elucida-
tion of the coordination site of each ylide ligand comes from
the observation of a very strong nOe interaction between the
H6 proton of the dmba ligand (ortho to the cyclometalated
position) at 6.27 ppm with the methine proton at 3.05 ppm,
attributed to the C-bonded ylide. Thus, the C-bonded ylide is
trans to the NMe2 group and the N-coordinated ylide is trans
to the ortho-metalated C6H4 group, as is depicted in Scheme 1.
Bond Distances
Pd(1)-C(1) 2.003 (4)
Pd(1)-N(1) 2.132 (3) Pd(1)-N(2) 2.076 (3)
Pd(1)-P(1) 2.2070 (10) N(2)-C(13) 1.156 (5) C(13)-C(14) 1.379 (5)
P(2)-C(14) 1.710 (4)
P(2)-C(27) 1.795 (4)
P(1)-O(3) 1.575 (3)
P(2)-C(15) 1.796 (4) P(2)-C(21) 1.814 (4)
P(1)-O(1) 1.589 (3) P(1)-O(2)
1.590 (3)
Bond Angles
82.17 (13) N(1)-Pd(1)-N(2)
91.42 (9) P(1)-Pd(1)-C(1)
C(1)-Pd(1)-N(1)
N(2)-Pd(1)-P(1)
92.37 (12)
94.34 (11)
Pd(1)-N(2)-C(13) 177.1 (3)
C(13)-C(14)-P(2) 118.4 (3)
N(2)-C(13)-C(14) 177.7 (4)
biotic behavior of the PdII center.20 Thus, the PR3 ligand, which
is a soft base, will be stabilized trans to the hard N atom
(phosphines are very reluctant to bond trans to the carbon atom21
) and the position trans to the soft ortho-metalated carbon atom
would be occupied by the hardest donor atom of the CPPY
ligand, that is, the N atom, with C-coordination of the ylide
trans to the ortho-metalated carbon atom being unfavorable.
Moreover, these results bear a strong resemblance to those
obtained for the R-keto stabilized ylides Ph3PdC(H)COR (R
) Me, Ph, OMe).4,18 We will return to this point presently.
Reactions of [Pd(CkN)(NCMe)2](ClO4) with CPPY. The
reaction of [Pd(CkN)(NCMe)2](ClO4) (3, 3′; see Scheme 1) with
CPPY (1:2 molar ratio) in CH2Cl2 at room temperature gives,
after solvent evaporation and Et2O addition, white solids of
stoichiometry [Pd(CkN)(CPPY)2](ClO4) (CkN = dmba 7, (R)-
dmphea 8), as characterized by their elemental analyses and
mass spectra (+FAB).
It is expected that the C-bonded ylide would display very
different spectroscopic parameters with respect to those observed
in the free ylide or in the N-bonded ylide as a result of the
hybridization change sp2 f sp3 at the ylidic carbon atom.1 Thus,
the methine PCH signal has been shifted downfield by about 2
2
ppm and shows a notably higher value of JP-H than the
N-coordinated ylide (13.8 Vs 6.0 Hz). In the same way, the
ylidic phosphorus resonance PCH of the C-coordinated ylide
has also been shifted downfield (approximately 2.5 ppm) while
the ylidic carbon resonance PCH is shifted upfield with respect
to the N-bonded form and has a coupling constant with one-
third of the corresponding value seen in the free ylide or in the
N-bonded form.
Similar conclusions can be derived from the NMR spectra
of 8, although in this case, due to the presence of a chiral center
in the (R)-dmphea ligand, two sets of signals, corresponding to
the two possible diastereoisomers (RR/RS) are observed. The
two sets of signals (see Tables 1 and 2 and Experimental
Section) show that a negligible diastereoselective induction has
taken place, with the major/minor diastereomeric ratio being
1.2/1, although we have not determined the absolute configu-
ration of each isomer.
The IR spectra of 7 and 8 (Table 1) show strong absorptions
at 2174 and 2172 cm-1, respectively, corresponding to the ν-
(CN) of the nitrile. The position of these absorptions indicates,
as for 4-6, that both the C-coordination and/or the N-
coordination modes could account for the positive observed ∆ν
values. The NMR spectra are rather more informative about
the structures of 7 and 8.
The selectivity observed in the coordination modes of the
ylides in 7 and 8 seems to be related to that observed in
complexes 4-6. Once again, consideration of the antisymbiotic
behavior of the soft PdII center20 provides a useful tool. Thus,
the ylidic carbon atom of the C-linked ylide is a soft base, and
it will be particularly stabilized when coordinated trans to the
harder donor atom of the cyclometalated ligand, that is, the N
atom. On the other hand, we have seen in 4-6 that the harder
N atom of the ylide can be accommodated trans to the soft
carbon of the ortho-metalated C6H4 group. This noteworthy
isomerism of the ligand, similar to that observed in the well-
known example of [Pd(Ph2PCH2CH2CH2NMe2)(NCS)(SCN)],23
has no precedent for ylides and clearly shows the ambidentate
character of this ylide ligand.
1
The H NMR spectrum (Table 2) of 7 shows, in addition to
the low-field resonances of the Ph and C6H4 groups, an AB
spin system for the CH2N protons and two singlet resonances
for the CH3 protons of the NMe2 group, showing that the
molecular plane is not now a symmetry plane. Moreover, two
doublet resonances of relative intensity 1:1 at 3.05 and 1.45
ppm also appear and are attributed to the methinic PdCH
protons of the two coordinated ylides. The corresponding 2JP-H
values are 13.8 and 6.0 Hz, respectively. The 31P{1H} NMR
spectrum of 7 shows two singlet resonances of relative intensity
1:1 at 26.80 and 24.35 ppm, and in the 13C{1H} NMR spectrum
the ylidic PdCH carbons appear as two doublets, at δ 1.88 ppm
(1JP-C ) 136 Hz) and -1.25 ppm (1JP-C ) 46 Hz).
The comparison of these sets of resonances with those
obtained for 4-6 (which contain the ylide selectively N-
coordinated) and with those shown by [PdCl2(CPPY)2]22 (which
contains the ylide selectively C-coordinated) suggest that in 7
Other reactions with the solvated complexes [Pd(CkN)-
(NCMe)2](ClO4) were attempted. The reaction of [Pd(CkN)-
(NCMe)2](ClO4) (3, 3′; see Scheme 1) with CPPY (1:1 molar
ratio) in CH2Cl2 at room temperature gives the immediate
precipitation of white solids of stoichiometry [Pd(CkN)(CPPY)-
(ClO4)] (CkN = dmba 9, (R)-dmphea 10) as derived from their
elemental analyses. The extremely low solubility of these
compounds in the usual organic solvents precludes their analysis
in solution; NMR data are not available, nor are conductivity
measurements. In spite of this low solubility, mass spectra of
9 and 10 could be obtained. The mass spectrum of 9 shows
the presence of a single peak at 541 a.m.u., corresponding to
the stoichiometry [Pd(dmba)(CPPY)]+. That of 10 shows a peak
at 555 [Pd((R)-dmphea)(CPPY)]+ and another one at 1211,
corresponding to the binuclear species [Pd2((R)-dmphea)2-
(19) Davies, J. A.; Hartley, F. R. Chem. ReV. 1981, 81, 79.
(20) Pearson, R. G. Inorg. Chem. 1973, 12, 712
(21) (a) Pfeffer, M.; Grandjean, D.; Le Borgne, G. Inorg. Chem. 1981, 20,
4426. (b) Dehand, J.; Jordanov, J.; Pfeffer, M.; Zinsius, M. C. R. Acad.
Sci. Paris. Ser. C 1975, 281, 651. (c) Vicente, J.; Arcas, A.; Bautista,
D.; Tiripicchio, A.; Tiripicchio Camellini, M. New J. Chem. 1996,
20, 345 and references given therein.
(22) We prepared a sample of PdCl2(CPPY)2 in order to measure the
chemical shift δ(PCH) and the coupling constants 2JP-H and 1JP-C of
an authentic C-coordinated ylide.This complex has already been
prepared by Burmeister et al.,2c but the NMR spectroscopic data were
not reported. The product was obtained as a mixture of the RR/SS
and RS diastereoisomers. Data (CDCl3) are as follows: 1H δ(PCH)
) 3.74 ppm (2JP-H ) 12.7 Hz), 3.68 ppm (2JP-H ) 12.6 Hz); 31P-
{1H} δ(PCH) ) 28.19 and 27.26 ppm; 13C{1H} δ(PCH) ) -4.62
ppm (1JP-C ) 51.7 Hz), -5.84 ppm (1JP-C ) 52.0 Hz).
(23) Clark, G. R.; Palenick, G. J. Inorg. Chem. 1970, 9, 2754.

1140 Inorganic Chemistry, Vol. 36, No. 6, 1997
Falvello et al.
(CPPY)2(ClO4)]+ and suggesting that 9 and 10 are probably
dinuclear in nature.
13C{1H} NMR data (Table 2) are in keeping with these
conclusions. The molar ratio 11a/11b remains unchanged in
solution at room temperature; the same proportions of 11a and
11b are observed after 1 week in CDCl3 solution. As expected,
the NMR data of 12 show a similar behavior; the ylide breaks
the chloride bridging system, giving isomeric mononuclear
derivatives in which the ylide is C-coordinated (12a, obtained
as a mixture of the corresponding two diastereoisomers) and
N-bonded (12b, obtained as a single isomer since N-bonding
of the ylide does not create a second chiral center).
Once again, the 1H-1H NOESY spectrum, performed on
complex 11, shows that the C-coordinated ylide in 11a is cis to
the C6H4 ortho-metalated group (and trans to the NMe2 unit),
as reflected by the strong nOe interaction between the resonance
at 4.37 ppm (methine proton, 11a) and the resonance at 6.68
ppm (H6 of the dmba ligand). Less clear is the coordination
site of the N-coordinated nitrile in 11b (the NOESY spectrum
is not informative in this respect, due to the remote location of
the methine proton with respect to any proton of the dmba
system). However, due to the fact that only one isomer has
been detected for 11b (and for 12b), and by analogy with the
splitting of the Pd(µ-Cl)2Pd system by N-donor ligands,9 we
propose an N-trans-to-N ligand arrangement (therefore, C-trans-
to-Cl) for complexes 11b and 12b.
Excluding the chelation of the ligand because of the constraint
imposed by the nitrile group, we can propose two possible
structures for 9 and 10; one is mononuclear with a covalent
perchlorate ligand, and one is binuclear with the ylide acting
as a bridging ligand. The IR spectra of 9 and 10 (Table 1)
-
show two interesting features: the absorptions due to the ClO4
anion are not split, as expected for the low symmetry (C3V)
monodentate ligand24,25 -OClO3 group; on the other hand, the
ν(CN) absorption appears as a strong, sharp band at 2224 cm-1
(9) or 2229 cm-1 (10), shifted to higher energies with respect
-
to the values found in 7 or 8. These facts suggest that the ClO4
anion is not included in the coordination sphere of the palladium
(excluding a mononuclear structure), and the increase of the
ν(CN) frequency strongly suggests that both the N- and the
C-atoms of the ylide are bonded to the palladium center (both
C- and N-coordination produce an increase of the ν(CN)
frequency). A dimeric structure such as that depicted in Scheme
1 accounts for these observations.
Further evidence can be obtained from the observed reactivity
(see Scheme 1). Thus, 9 can be obtained by reaction of 7 and
[Pd(dmba)(NCMe)2]+ (3) in equimolecular amounts, and in-
versely, the reaction of 9 with 2 equiv of CPPY gives 7
exclusively. Complex 9 also reacts with PPh3 (1:2 molar ratio)
producing bridge splitting and giving 4 in quantitative yield (see
Experimental Section). However, while the free ylide or PPh3
is able to produce bridge splitting in 9, no reaction was observed
between 9 and CO, Cl-, or pyridine, ligands which could easily
replace a bound perchlorate.26
Reactions of [Pd(µ-Cl)(CkN)]2 with CPPY. The reactions
of the binuclear chloride-bridged complexes [Pd(µ-Cl)(CkN)]2
(1, 1′; see Scheme 1) with CPPY (1:2 molar ratio) in CH2Cl2
at room temperature give, after solvent evaporation and Et2O
addition, pale yellow solids of stoichiometry [PdCl(CkN)-
(CPPY)] (CkN = dmba 11, (R)-dmphea 12) as characterized
by elemental analysis. The neutral nature of these complexes
is inferred from their nonconducting behavior in acetone
solutions (see Experimental Section). Moreover, the determi-
nation of the molecular weight in solution for 12 (see Experi-
mental Section) gives an excellent agreement between the
measured and theoretical values.
Conclusion
The ylide Ph3PdC(H)CN (CPPY) behaves as an ambidentate
ligand toward ortho-metalated derivatives of PdII. Depending
on the starting material used, we have found examples in which
the ylide is selectively N-coordinated, compounds with C-
coordination, a mixture of isomers C- and N-coordinated isomers
and even complexes containing two ylides, one of them C- and
the other one N-coordinatedsa fascinating example of ligand
isomerism. Moreover, we have inferred the nature of products
in which this ylide acts as a bridging ligand. This rich
coordination chemistry, which has been almost exclusive by in
the domain of classical polidentate ligands, is unprecedented
for the R-stabilized ylide ligands and allows us to suspect that
new and more interesting results may await study.
Experimental Section
Safety 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 ref 27.
The IR spectra of 11 and 12 (Table 1) show the expected
ν(CN) absorption at 2178 (11) or 2187 (12) cm-1. The increase
of ν(CN) with respect to the free ylide indicates that the ligand
is actually coordinated in 11 and 12 and that these products are
General Procedures. Solvents were dried and distilled under
nitrogen before use: diethyl ether and tetrahydrofuran over sodium
benzophenone ketyl; dichloromethane over P2O5 and n-hexane over
sodium. Elemental analyses were carried out on a Perkin-Elmer 2400
microanalyzer. Infrared spectra (4000-200 cm-1) were recorded on a
Perkin-Elmer 883 infrared spectrophotometer in Nujol mulls between
polyethylene sheets. 1H (300.13 MHz), 13C{1H} (75.47 MHz), and
31P{1H} (121.49 MHz) NMR spectra were recorded in CDCl3 solutions
at room temperature (unless otherwise stated) on a Bruker ARX-300
spectrometer; 1H and 13C{1H} were referenced using the solvent signal
as internal standard and 31P{1H} was externally referenced to H3PO4
1
not simply mixtures of the starting materials. The H NMR
spectrum of 11 gives additional information. Two sets of signals
(relative intensity ) 1.2/1) are observed, indicating the presence
of two isomers. The major isomer shows singlet resonances
for the CH2N and NMe2 protons, and a doublet for the methine
PCH proton at 1.92 ppm (2JP-H ) 6.5 Hz). The minor isomer
shows diastereotopic CH2N protons, two singlets for the NMe2
group and a doublet for the methine proton at 4.37 ppm (2JP-H
) 14.3 Hz). Using reasoning similar to that applied in our
earlier discussion of the NMR of complexes 4-8, we conclude
that in the major isomer the ylide is N-bonded (11b) and that
in the minor one the ylide is C-coordinated (11a), as has been
depicted in Scheme 1. Thus, both C(ylide) and N(nitrile) atoms
are able to produce bridge splitting in [Pd(µ-Cl)(CkN)]2, giving
an almost equimolar distribution of products. The 31P{1H} and
1
(85%). The two dimensional H-1H NOESY experiments for com-
plexes 7 and 11 were performed at a measuring frequency of 300.13
MHz. The data were acquired into a 512 × 1024 matrix, and then
transformed into 1024 × 1024 points using a sine window in each
dimension. The mixing time was 400 ms. Mass spectra (positive ion
FAB) were recorded on a V. G. Autospec spectrometer. Molecular
weight determinations were made on a Knauer vapor pressure osmom-
eter. Electrical conductivity measurements were performed in acetone
solutions with concentrations around 5 × 10-4 M with a Philips PW
(24) Rosenthal, M. R. J. Chem. Educ. 1973, 50, 331.
(25) Nakamoto, K. In Infrared and Raman Spectra of Inorganic and
28
9509 conductivity cell. The starting complexes [Pd(µ-Cl)(CkN)]2
Coordination Compounds, 3rd ed.; Wiley: New York, 1978; pp 242-
243.
(26) Uso´n, R.; Fornie´s, J.; Mart´ınez, F. J. Organomet. Chem. 1976, 112,
(27) J. Chem. Educ. 1973, 50, A335.
(28) Cope, A. C.; Friedrich, E. C. J. Am. Chem. Soc. 1968, 90, 909.
105.

Nitrogen vs Carbon Coordination
Inorganic Chemistry, Vol. 36, No. 6, 1997 1141
(CkN = dmba 1 and (R)-dmphea 1′), [PdCl(CkN)(PR′3)]9 [PR′3 ) PPh3;
CkN = dmba 2, (R)-dmphea 2′; PR′3 ) P(OMe)3; CkN = dmba 2′′),
[Pd(CkN)(NCMe)2](ClO4)29 [CkN = dmba 3, (R)-dmphea 3′], and the
ylide Ph3PdC(H)CN (CPPY)3a were prepared according to published
methods.
{Pd(dmba)[C(H)(CtN)(PPh3)][NtCsC(H)dPPh3]}(ClO4), 7.
To a solution of [Pd(dmba)(NCMe)2](ClO4) 3 (0.155 g, 0.367 mmol)
in 25 mL of CH2Cl2 at room temperature was added CPPY (0.221 g,
0.734 mmol). A white cloudiness was immediately observed which,
upon stirring, gradually dissipated. After 2 h of stirring at room
temperature, a very small amount of white solid remained in suspension.
This suspension was filtered, the solid discarded, and the clear solution
evaporated to a small volume (ca. 3 mL). By addition of Et2O (25
mL) and continuous stirring, 7 was obtained as a white solid, which
was filtered and air-dried. Yield: 0.262 g (77% yield).
Anal. Calcd for C49H44ClN3O4P2Pd (Mr ) 942.71): C, 62.43; H,
4.70; N, 4.45. Found: C, 62.02; H, 4.84; N, 4.50. MS (+FAB) [m/z
(%)]: 842 (28%) [M+]; 541 (100%) [(M - ylide)+]. IR (νCN, cm-1):
2174. 1H: δ 7.89-7.82 (m, Ph), 7.65-7.40 (m, Ph), 6.79 (m, 2H,
{Pd(dmba)(PPh3)[NtCsC(H)dPPh3]}(ClO4), 4. To a solution
of PdCl(dmba)(PPh3) 2 (0.129 g, 0.239 mmol) in THF (25 mL) was
added AgClO4 (0.049 g, 0.239 mmol), and the resulting suspension
was stirred for 30 min at room temperature with exclusion of light.
The insoluble AgCl was filtered off, and the freshly obtained pale
yellow solution was cooled at 0 °C and then CPPY (0.072 g, 0.239
mmol) was added. After 30 min of stirring at 0 °C, the solvent was
evaporated to dryness and the oily residue treated with 25 mL of Et2O,
giving complex 4 as a white solid, which was filtered and air-dried.
Yield: 0.173 g (80% yield). Crude 4 was recrystallized from CH2-
Cl2/n-hexane. The white crystals of 4‚0.25CH2Cl2 were used for
elemental analysis and NMR measurements. The amount of CH2Cl2
3
4
C6H4), 6.79 (td, 1H, C6H4, JH-H ) 7.6 Hz, JH-H ) 2 Hz), 6.27 (d,
2
1H, C6H4), 3.72, 3.61 (AB spin system, 2H, CH2N, JH-H ) 14 Hz),
2
3.05 (d, 1H, CH C-ylide, JP-H ) 13.8 Hz), 2.25 (s, 3H, NMe2), 1.98
(s, 3H, NMe2), 1.45 (d, 1H, CH N-ylide, JP-H ) 6.0 Hz). 31P{1H}:
2
1
of crystallization was determined by H NMR integration.
δ 26.80 (-P+Ph3, C-ylide), 24.35 (dPPh3, N-ylide). 13C {1H}: δ
148.22, 147.25, 132.19, 125.16, 124.12, 122.55 (C6H4), 134.43, 134.15
(JP-C ) 10 Hz), 133.42, 132.76 (JP-C ) 10 Hz), 129.51 (JP-C ) 13
Hz), 125.15 (1JP-C ) 92 Hz) (PPh3), 121.71, 120.55 (CN), 72.14
Anal. Calcd for C47H43ClN2O4P2Pd.0.25CH2Cl2 (Mr ) 924.90): C,
61.36; H, 4.74; N, 3.02. Found: C, 61.43; H, 4.58; N, 2.99. MS
(+FAB) [m/z (%)]: 803 (21%) [M+]; 502 (100%) [(M - ylide)+]. IR
(νCN, cm-1): 2158. 1H: δ 7.69-7.35 (m, 30H, Ph), 6.94 (d, 1H, C6H4,
1
3
3JH-H ) 7 Hz), 6.79 (false t, 1H, C6H4, JH-H ) 7 Hz), 6.33 (false t,
(CH2N), 51.21, 50.33 (NMe2), 1.88 (CH N-ylide, JP-C ) 136 Hz),
-1.25 (CH C-ylide, JP-C ) 46 Hz).
1
3
4
1H, C6H4), 6.19 (false t, 1H, C6H4, JH-H = JP-H ) 7 Hz), 3.94 (d,
2H, CH2N, 4JP-H ) 1.8 Hz), 2.30 (d, 6H, NMe2, 4JP-H ) 2.5 Hz), 1.24
(d, 1H, CH ylide, 2JP-H ) 5.4 Hz). 31P{1H}: δ 42.40 (Pd-PPh3), 24.17
(dPPh3). 13C {1H}: δ 149.18, 146.40, 137.95 (JP-C ) 11 Hz), 130.32,
125.20 (JP-C ) 15 Hz), 124.82 (C6H4), 134.86 (JP-C ) 12 Hz), 133.62,
132.68 (JP-C ) 10 Hz), 131.27, 129.55 (JP-C ) 13 Hz), 128.63 (JP-C
) 11 Hz), 125.07 (1JP-C ) 93 Hz) (PPh3), 123.00 (CN), 71.97 (CH2N),
{Pd((R)-dmphea)[C(H)(CtN)(PPh3)][NtCsC(H)dPPh3]}-
(ClO4), 8. Complex 8 was obtained in a manner similar to that for 7:
[Pd((R)-dmphea)(NCMe)2](ClO4) 3′ (0.146 g, 0.335 mmol) reacted in
CH2Cl2 at room temperature with CPPY (0.202 g, 0.670 mmol) to give
8 as a white solid. Yield: 0.260 g (81% yield). Diastereomeric ratio:
major/minor: 1.2/1. Complex 8 was recrystallized from CH2Cl2/n-
hexane. The white microcrystalline solid of 8.0.35CH2Cl2 was used
for analytical and spectrocopic measurements. The amount of CH2Cl2
1
50.35 (NMe2), 1.49 (CH ylide, JP-C ) 136 Hz).
{Pd(dmba)[P(OMe)3][NtCsC(H)dPPh3]}(ClO4), 5. Complex 5
was synthesized in a manner similar to that used for 4: {Pd(dmba)-
[P(OMe)3](THF)}(ClO4) (prepared from PdCl(dmba)[P(OMe)3] 2′′
(0.196 g, 0.489 mmol) and AgClO4 (0.101 g, 0.489 mmol)) reacted, in
THF at 0 °C, with CPPY (0.147 g, 0.489 mmol) to give 5 as a white
solid. Yield: 0.246 g (65% yield).
1
of crystallization was determined by H NMR integration.
Anal. Calcd for C50H46ClN3O4P2Pd.0.35CH2Cl2 (Mr ) 986.46): C,
61.30; H, 4.77; N, 4.26. Found: C, 61.14; H, 4.93; N, 3.98. MS
(+FAB) [m/z (%)]: 856 (31%) [M+]; 555 (100%) [(M - ylide)+]. IR
(νCN, cm-1): 2172. 1H: δ 7.92-7.77 (m, Ph), 7.67-7.40 (m, Ph),
6.80-6.43 (m, 4H, C6H4, both isomers), 3.50 (q, 1H, CH-dmphea,
Anal. Calcd for C32H37ClN2O7P2Pd (Mr ) 765.43): C, 50.21; H,
4.87; N, 3.66. Found: C, 49.80; H, 4.93; N, 3.64. MS (+FAB) [m/z
(%)]: 665 (100%) [M+]; 541 (50%) [(M - phosphite)+]; 364 (100%)
[(M-ylide)+]. IR (νCN, cm-1): 2181. 1H: δ 7.69-7.54 (m, 15H, Ph),
7.10 (m, 1H, C6H4), 6.95 (m, 2H, C6H4), 6.87 (m, 1H, C6H4), 3.94 (d,
3
major isomer, JH-H ) 6.5 Hz), 3.47 (q, 1H, CH-dmphea, minor
3
2
isomer, JH-H ) 6.5 Hz), 3.11 (d, 1H, CH C-ylide, minor, JP-H
)
2
14.0 Hz), 3.08 (d, 1H, CH C-ylide, major, JP-H ) 13.3 Hz), 2.40 (s,
3H, NMe2, major), 2.09 (s, 3H, NMe2, minor), 1.99 (s, 3H, NMe2,
minor), 1.79 (s, 3H, NMe2, major), 1.41 (d, 1H, CH N-ylide, major,
4
3
2H, CH2N, JP-H ) 2.7 Hz), 3.59 (d, 9H, -OMe, JP-H ) 13 Hz),
2JP-H ) 5.9 Hz), 1.38 (d, 1H, CH N-ylide, minor, JP-H ) 5.9 Hz),
2
4
2
2.38 (d, 6H, NMe2, JP-H ) 3.9 Hz), 2.03 (d, 1H, CH ylide, JP-H
)
1.34 (d, 3H, Me-dmphea, major), 1.28 (d, 3H, Me-dmphea, minor).
31P{1H}: δ 27.25 (-P+Ph3, C-ylide, minor), 26.62 (-P+Ph3, C-ylide,
major), 24.52 (dPPh3, N-ylide, major), 24.28 (dPPh3, N-ylide, minor).
13C{1H}: δ 154.18, 154.03, 152.76, 146.83, 132.39, 132.26, 125.38,
125.16, 124.40, 124.13, 122.68, 122.58 (C6H4, both isomers), 134.84,
134.37 (JP-C ) 11 Hz), 134.08 (JP-C ) 13 Hz), 133.39, 132.76 (JP-C
) 10 Hz), 129.59 (JP-C ) 12 Hz), 129.49 (JP-C ) 13 Hz), 125.53
(1JP-C ) 92 Hz) (PPh3), 121.90, 120.74 (CN, minor), 121.68, 120.52
(CN, major), 74.36 (CH-dmphea, minor), 74.25 (CH-dmphea, major),
51.24, 45.82 (NMe2, major), 50.65, 46.42 (NMe2, minor), 20.43 (Me-
dmphea, major), 20.12 (Me-dmphea, minor), 2.20 (CH N-ylide, minor,
5.2 Hz). 31P{1H}: δ 118.84 (Pd-P(OMe)3), 24.68 (dPPh3). 13C
{1H}: δ 149.03 (JP-C ) 4 Hz), 145.43, 136.40 (JP-C ) 12 Hz), 133.21
(JP-C ) 8 Hz), 126.27 (JP-C ) 7 Hz), 125.58 (C6H4), 133.66 (4JP-C
)
2 Hz), 132.72 (3JP-C ) 10 Hz), 129.63 (2JP-C ) 13 Hz), 125.16 (1JP-C
3
) 93 Hz) (PPh3), 123.47 (CN), 71.51 (CH2N, JP-C ) 4 Hz), 53.07
(OMe), 49.93 (NMe2, JP-C ) 3 Hz), 1.64 (CH ylide, JP-C ) 135
Hz).
3
1
{Pd((R)-dmphea)(PPh3)[NtCsC(H)dPPh3]}(ClO4), 6. Complex
6 was synthesized in a manner similar to that used for 4: [Pd((R)-
dmphea)(PPh3)(THF)](ClO4) (prepared from PdCl((R)-dmphea)(PPh3)
2′ (0.308 g, 0.556 mmol) and AgClO4 (0.115 g, 0.556 mmol)) reacted,
in THF at 0 °C, with CPPY (0.167 g, 0.556 mmol) to give 6 as a white
solid. Yield: 0.420 g (82% yield).
Anal. Calcd for C48H45ClN2O4P2Pd (Mr ) 917.70): C, 62.82; H,
4.94; N, 3.05. Found: C, 62.54; H, 5.29; N, 2.90. MS (+FAB) [m/z
(%)]: 817 (75%) [M+]; 555 (22%) [(M - phosphine)+]; 516 (100%)
[(M - ylide)+]. IR (νCN, cm-1): 2166. 1H: δ 7.67-7.31 (m, 30H,
Ph), 6.90 (dd, 1H, C6H4, 3JH-H ) 7.5 Hz, 4JH-H ) 1.3 Hz), 6.79 (false
t, 1H, C6H4, 3JH-H ) 7 Hz), 6.33 (false t, 1H, C6H4), 6.19 (false t, 1H,
1
1JP-C ) 136 Hz), 1.94 (CH N-ylide, major, JP-C ) 136 Hz), -1.48
(CH C-ylide, minor, 1JP-C ) 46 Hz), -1.67 (CH C-ylide, major, 1JP-C
) 46 Hz).
{Pd(dmba)[µ-C,N-Ph3PCHCN]}2(ClO4)2, 9. To a solution of [Pd-
(dmba)(NCMe)2](ClO4) 3 (0.200 g, 0.473 mmol) in 25 mL of CH2Cl2
at room temperature was added CPPY (0.142 g, 0.473 mmol). A white
solid precipitated immediately. The suspension was stirred for 30 min
and filtered, and the solid 9 was washed with CH2Cl2 (20 mL) and
air-dried. Yield: 0.240 g (80% yield). Complex 9 can also be obtained
by reaction of 7 (0.045 g, 0.047 mmol) with [Pd(dmba)(NCMe)2](ClO4)
3 (0.020 g, 0.047 mmol) in CH2Cl2 (5 mL). After 24 h of stirring at
room temperature, 9 precipitated as a white solid.
Anal. Calcd for C58H56Cl2N4O8P2Pd2 (Mr ) 1282.76): C, 54.31;
H, 4.40; N, 4.37. Found: C, 53.92; H, 4.08; N, 4.30. MS (+FAB)
[m/z (%)]: 541 (35%) {[Pd(dmba)(Ph3PCHCN)]+}. IR (νCN, cm-1):
2224. Further characterization was not possible due to its extremely
low solubility in the usual organic solvents.
3
4
3
C6H4, JH-H = JP-H ) 7 Hz), 3.69 (q, 1H, CH-dmphea, JH-H ) 6
Hz), 2.43 (d, 3H, NMe2, 4JP-H ) 1.8 Hz), 2.06 (d, 3H, NMe2, 4JP-H
)
)
2
3.2 Hz), 1.62 (d, 3H, Me-dmphea), 1.26 (d, 1H, CH ylide, JP-H
5.4 Hz). 31P{1H}: δ 41.70 (Pd-PPh3), 24.24 (dPPh3). 13C {1H}: δ
155.03, 145.97, 137.86 (JP-C ) 12 Hz), 130.41, 125.12 (JP-C ) 5 Hz),
124.85 (C6H4), 134.79 (JP-C ) 12 Hz), 133.60, 132.69 (JP-C ) 10 Hz),
131.23, 129.53 (JP-C ) 13 Hz), 128.63 (JP-C ) 10 Hz), 125.09 (1JP-C
) 93 Hz) (PPh3), 122.91 (CN), 74.43 (CH-dmphea), 50.53, 46.28
1
(NMe2), 22.06 (Me-dmphea), 1.53 (CH ylide, JP-C ) 136 Hz).
Reactions Performed in the NMR Tube. (a) Complex 9 and PPh3
(molar ratio 1:2) were suspended in 0.4 mL of CDCl3 and transferred
(29) Fornie´s, J.; Navarro, R.; Sicilia, V. Polyhedron 1988, 7, 2659.

1142 Inorganic Chemistry, Vol. 36, No. 6, 1997
Falvello et al.
to an NMR tube. After 18 h at room temperature, the initial suspension
had dissolved. The 1H and 31P{1H} NMR spectra of this solution show
the presence of 4 as the unique product of reaction. (b) To a suspension
of 9 in CDCl3 (0.4 mL) was added 2 equiv of CPPY. The initial
suspension gradually dissolved, and after 12 h at room temperature,
the 1H and 31P{1H} NMR spectra of this solution showed the presence
of 7 as the unique product of reaction.
{Pd((R)-dmphea)[µ-C,N-Ph3PCHCN]}2(ClO4)2, 10. To a solution
of [Pd((R)-dmphea)(NCMe)2](ClO4) 3′ (0.200 g, 0.457 mmol) in 25
mL of CH2Cl2 at room temperature was added CPPY (0.137 g, 0.457
mmol). A white solid precipitated immediately. The suspension was
stirred for 30 min and filtered, and the solid 10 was washed with CH2-
Cl2 (20 mL) and air-dried. Yield: 0.211 g (66% yield).
Anal. Calcd for C60H60Cl2N4O8P2Pd2 (Mr ) 1310.81): C, 54.98;
H, 4.61; N, 4.27. Found: C, 54.62; H, 4.80; N, 4.25. MS (+FAB)
[m/z (%)]: 1211 (10%) {[Pd2(R-dmphea)2(Ph3PCHCN)2(ClO4)]+}; 555
(35%) {[Pd(R-dmphea)(Ph3PCHCN)]+}. IR (νCN, cm-1): 2229. Fur-
ther characterization was not possible due to its extremely low solubility
in the usual organic solvents.
{PdCl(dmba)[C(H)(CN)(PPh3)]}, 11a, {PdCl(dmba)[NCsC-
(H)dPPh3]}, 11b. To a solution of [Pd(µ-Cl)(dmba)]2 (1) (0.200 g,
0.362 mmol) in 25 mL of CH2Cl2 was added CPPY (0.218 g, 0.724
mmol). The resulting pale yellow solution was stirred at room
temperature for 30 min and the solvent was then evaporated to dryness.
By addition of Et2O (25 mL) to the oily residue and continuous stirring,
11 (as a mixture of 11a and 11b) was obtained as a pale yellow solid,
which was filtered and air-dried. Yield: 0.345 g (83% yield). Isomeric
ratio: C-coordinated (11a)/N-coordinated (11b) ) 1/1.2.
124.75, 123.76, 123.09, 122.95 (C6H4), 134.30 (JP-C ) 10 Hz), 133.70,
133.59, 132.85 (JP-C ) 10 Hz), 129.29 (JP-C ) 12 Hz), 129.01 (JP-C
) 11 Hz), 126.07 (1JP-C ) 93 Hz) (PPh3), 122.17, 121.52, 121.20 (CN),
75.89 (2C), 75.34 (CH-dmphea), 52.15, 47.21 (NMe2, 12b), 51.25,
48.16 (NMe2, 12a, major), 50.39, 47.07 (NMe2, 12a, minor), 22.47
(Me-dmphea, 12a, minor), 22.40 (Me-dmphea, 12a, major), 19.25
1
(Me-dmphea, 12b), 1.89 (CH-ylide, 12b, JP-C ) 137 Hz), -7.07
1
(CH-ylide, 12a, both isomers, JP-C ) 46 Hz).
X-ray Crystal Structure Determination of 5. Data Collection.
Crystals suitable for X-ray analysis were grown by slow diffusion of
n-hexane into a CH2Cl2 solution of 5 at -18 °C. A crystal of
dimensions 0.40 × 0.35 × 0.30 mm was mounted at the end of a quartz
fiber and covered with epoxy. Geometric and intensity data were taken
at 150 K using normal procedures on an Enraf-Nonius CAD4 automated
four-circle diffractometer. After initial indexing of the cell, axial photos
were taken for the axes a, b, c and [111] in order to check the lattice
dimensions. The scan parameters for intensity data collection were
chosen on the basis of two dimensional (ω-θ) plots of 25 reflections.
Data were collected using a variable scan-speed technique in which
the weakest data were measured at the slowest scan speed. That is to
say, no measurement was skipped or measured rapidly because of weak
diffraction. Azimuthal scans of 19 scattering vectors were used as the
basis of an absorption correction. No intensity decay was observed in
three monitor reflections that were remeasured every 3 h during data
collection. Crystal orientation was checked by measuring three standard
reflections every 400 reflections during data collection. The cell
parameters were refined to the accurately determined positions of 25
reflections (22.6 e 2θ e 31.6°), each measured at four different
positions.
Structure Solution and Refinement. After data reduction, the
heavy atoms (Pd, P) of one asymmetric unit were located by an
automated procedure that incorporates Patterson analysis, difference
direct methods, and Fourier peaklist optimization.30 The remaining non-
hydrogen atoms and the hydrogen atom of the ylidic carbon were found
from subsequent difference Fourier syntheses. The structure was refined
to Fo2, and all positive data were used in the refinement.31 The remaining
hydrogen atoms of the cation were placed in idealized positions and
treated as riding atoms, except for those of the methyl groups, which
were first located in a local slant-Fourier calculation and then refined
as riding atoms with the torsion angles about the O-C(methyl) or
N-C(methyl) bonds treated as variables. Each hydrogen atom was
assigned an isotropic displacement parameter equal to 1.2 times the
equivalent isotropic displacement parameter of its parent atom. The
perchlorate anion was found to be disordered and it was modeled as
three equally populated congeners occupying the same interstice and
with the chlorine atom common to the three components. During the
final refinement, the bonded and 1-3 distances of all three perchlorate
moieties were restrained to be similar. The refinement converged with
the residuals shown in Table 3.32
Anal. Calcd for C29H28ClN2PPd (Mr ) 577.38): C, 60.32; H, 4.89;
N, 4.85. Found: C, 60.38; H, 4.77; N, 4.66. ΛM (Ω-1 cm2 mol-1):
2.64 (5 × 10-4 M in acetone solution). IR (νCN, cm-1): 2178. 1H: δ
7.92-7.85 (m, Ph), 7.63-7.40 (m, Ph), 6.79, 6.68, 6.46, 6.36 (m, 4H,
2
C6H4, both isomers), 4.37 (d, 1H, CH ylide 11a, JP-H ) 14.3 Hz),
2
3.94, 3.42 (AX spin system, 2H, CH2N 11a, JH-H ) 13 Hz), 3.79 (s,
2H, CH2N 11b), 2.78 (s, 6H, NMe2, 11b), 2.68 (s, 3H, NMe2 11a),
2.48 (s, 3H, NMe2 11a), 1.92 (d, 1H, CH-ylide 11b, 2JP-H ) 6.5 Hz).
31P{1H}: δ 28.07 (-P+Ph3, 11a), 23.66 (dPPh3, 11b). 13C {1H}: δ
147.34, 147.17, 146.87, 146.22, 132.06, 131.93, 128.55, 128.39, 125.00,
124.68, 123.80, 123.05 (C6H4, both isomers), 134.37 (JP-C ) 10 Hz),
133.75, 133.00, 132.86 (JP-C ) 10 Hz), 129.31 (JP-C ) 13 Hz), 129.03
(JP-C ) 12 Hz), 126.06 (1JP-C ) 92 Hz) (PPh3), 121.61, 121.04 (CN),
74.10, 73.09 (CH2N), 52.60 (NMe2 11b), 52.14, 50.13 (NMe2 11a),
1
1
1.94 (CH-ylide 11b, JP-C ) 137 Hz), -6.04 (CH-ylide 11a, JP-C
) 46 Hz).
{PdCl((R)-dmphea)[C(H)(CN)(PPh3)]}, 12a, {PdCl((R)-dmphea)-
[NCsC(H)dPPh3]}, 12b. To a solution of [Pd(µ-Cl)((R)-dmphea)]2
1′ (0.236 g, 0.406 mmol) in 25 mL of CH2Cl2 was added CPPY (0.245
g, 0.813 mmol). The resulting pale yellow solution was stirred at room
temperature for 30 min and the solvent was then evaporated to dryness.
By addition of Et2O (25 mL) to the oily residue and continuous stirring,
12 (as a mixture of 12a and 12b) was obtained as a pale yellow solid,
which was filtered and air-dried. Yield: 0.359 g (75% yield). Isomeric
ratio: C-coordinated (12a)/N-coordinated (12b) ) 1/1. Diastereomeric
ratio in 12a: major/minor ) 1.8/1.
Acknowledgment. We thank the Direccio´n General de
Investigacio´n Cient´ıfica y Te´cnica (Spain) for financial support
(Projects PB92-0360 and PB92-0364) and Prof J. Fornie´s for
invaluable logistical support.
Anal. Calcd for C30H30ClN2PPd (Mr ) 591.41): C, 60.92; H, 5.11;
N, 4.73. Found: C, 60.62; H, 5.24; N, 4.46. ΛM (Ω-1 cm2 mol-1):
1.90 (5 × 10-4 M in acetone solution). Mol wt (CHCl3): found, 592.41
(calcd, 591.41). IR (νCN, cm-1): 2187. 1H: δ 7.89-7.82 (m, Ph),
7.62-7.38 (m, Ph), 6.80-6.22 (m, C6H4, both isomers), 4.58 (d, 1H,
CH-ylide 12a, major, 2JP-H ) 14.0 Hz), 4.29 (d, 1H, CH-ylide 12a,
minor, 2JP-H ) 14.0 Hz), 3.80 (q, 1H, CH-dmphea 12a, major, 3JH-H
Supporting Information Available: X-ray crystallographic files
in CIF format for compound 5 are available on the Internet only.
Access information is given on any current masthead page.
IC960904E
(30) Sheldrick, G. M., SHELXS-86, Acta Crystallogr. 1990, A46, 467.
(31) Sheldrick, G. M., SHELXL-93: FORTRAN program for the refine-
ment of crystal structures from diffraction data. Go¨ttingen University,
1993.
(32) (a) Crystallographic calculations were done on a Local Area VAX-
Cluster (VAX/VMS V5.5-2). (b) Data reduction was done by the
program XCAD4B: Harms, K. Private communication, 1995. (c)
Absorption corrections and molecular graphics were done using the
commercial package: SHELXTL-PLUS, Release 4.21/V; Siemens
Analytical X-ray Instruments, Inc., Madison, WI, 1990.
3
) 6.5 Hz), 3.67 (q, 1H, CH-dmphea, 12b, JH-H ) 6 Hz), 3.22 (q,
1H, CH-dmphea 12a, minor, 3JH-H ) 6 Hz), 2.81, 2.59 (2s, 6H, NMe2
12b), 2.75, 2.33 (2s, 6H, NMe2 12a, minor), 2.54, 2.48 (2s, 6H, NMe2
2
12a, major), 1.90 (d, 1H, CH-ylide 12b, JP-H ) 6.5 Hz), 1.43 (d,
3H, Me-dmphea, 12b), 1.30 (d, 3H, Me-dmphea 12a, major), 1.26
(d, 3H, Me-dmphea 12a, minor). 31P{1H}: δ 28.31 (-P+Ph3, 12a,
minor), 27.94 (-P+Ph3, 12a, major), 23.62 (dPPh3, 12b). 13C{1H}:
δ 153.67, 152.38, 148.15, 146.32, 132.07, 131.91, 128.56, 128.49,