New palladium(II)-(η3/5- or η1-indenyl) and dipalladium(I)-(μ,η3-indenyl) complexes

Article abstract of DOI:10.1021/ja060747a

Reaction of the dimeric species [(η³-Ind)Pd(μ-CI)] ₂ (1) (Ind = indenyl) with NEt₃ gives the complex (η^3-5-Ind)Pd(NEt₃)CI (3), whereas the analogous reactions with BnNH₂ (Bn = PhCH₂) or pyridine (py) afford the complexes frans-L₂Pd(η¹-Ind)CI (L = BnNH ₂ (4), py (5)). Similarly, the one-pot reaction of 1 with a mixture of BnNH₂ and the phosphine ligands PR₃ gives the mixed-ligand, amino and phosphine species (PR₃)(BnNH ₂)Pd(η¹-Ind)CI (R = Cy (6a), Ph (6b)); the latter complexes can also be prepared by addition of BnNH₂ to (η^3-5-Ind)Pd(PR₃)CI (R = Cy (2a), Ph (2b)). Complexes 6 undergo a gradual decomposition in solution to generate the dinuclear Pd ^I compounds (μ,η³-Ind)(μ-CI)Pd ₂(PR₃)₂ (R = Cy (7a), Ph (7b)) and the Pd ^II compounds (BnNH₂)(PR₃)PdCI₂ (R = Cy (8a), Ph (Bb)), along with 1,1′-biindene. The formation of 7 is proposed to proceed by a comproportionation reaction between in situ-generated Pd^II and Pd⁰ intermediates. Interestingly, the reverse of this reaction, disproportionation, also occurs spontaneously to give 2. All new compounds have been characterized by NMR spectroscopy and, in the case of 3, 4, 5, 6a, 7a, 7b, and 8a, by X-ray crystallography.

Full text of DOI:10.1021/ja060747a

Published on Web 04/20/2006
New Palladium(II)-(η3/5- or η1-Indenyl) and
Dipalladium(I)-(µ,η3-Indenyl) Complexes
Christine Sui-Seng,† Gary D. Enright,‡ and Davit Zargarian*,†
Contribution from the De´partement de chimie, UniVersite´ de Montre´al, Que´bec,
Canada H3C 3J7, and Steacie Institute for Molecular Sciences, National Research Council,
Ottawa, Ontario, Canada K1A 0R6
Received February 7, 2006; E-mail: zargarian.davit@umontreal.ca
Abstract: Reaction of the dimeric species [(η3-Ind)Pd(µ-Cl)]2 (1) (Ind ) indenyl) with NEt3 gives the complex
(η3-5-Ind)Pd(NEt3)Cl (3), whereas the analogous reactions with BnNH2 (Bn ) PhCH2) or pyridine (py) afford
the complexes trans-L2Pd(η1-Ind)Cl (L ) BnNH2 (4), py (5)). Similarly, the one-pot reaction of 1 with a
mixture of BnNH2 and the phosphine ligands PR3 gives the mixed-ligand, amino and phosphine species
(PR3)(BnNH2)Pd(η1-Ind)Cl (R ) Cy (6a), Ph (6b)); the latter complexes can also be prepared by addition
of BnNH2 to (η3-5-Ind)Pd(PR3)Cl (R ) Cy (2a), Ph (2b)). Complexes 6 undergo a gradual decomposition
in solution to generate the dinuclear PdI compounds (µ,η3-Ind)(µ-Cl)Pd2(PR3)2 (R ) Cy (7a), Ph (7b)) and
the PdII compounds (BnNH2)(PR3)PdCl2 (R ) Cy (8a), Ph (8b)), along with 1,1′-biindene. The formation of
7 is proposed to proceed by a comproportionation reaction between in situ-generated PdII and Pd0
intermediates. Interestingly, the reverse of this reaction, disproportionation, also occurs spontaneously to
give 2. All new compounds have been characterized by NMR spectroscopy and, in the case of 3, 4, 5, 6a,
7a, 7b, and 8a, by X-ray crystallography.
Introduction
that the chemistry of group 10 metal-indenyl complexes is
much less explored. Nevertheless, a number of studies carried
Studies on the structures and reactivities of Ind complexes
(Ind ) indenyl and its substituted or functionalized derivatives)
have shown that the bonding mode adopted by the Ind ligand
and its net electronic contribution to the metal center in a given
complex depend strongly on the electronic configuration of the
metal (dn) and its formal electron count. Thus, the formally
electron-deficient complexes of early metals (d0-5, up to 18
valence electrons) generally favor greater hapticities (η5-Ind),1
whereas the more electron-rich late metal centers (d6-8, 16-18
valence electrons) favor lower hapticities and display various
degrees of “slip-fold” distortions (η1-5-Ind). This flexible and
responsive nature of M-Ind bonding, the so-called “indenyl
effect”, is believed to facilitate a number of interesting sto-
ichiometric and catalytic reactions.2
out over the past decade on NiII-Ind complexes IndNi(L)X and
[IndNi(L)L′]+ have shown that the Ind ligand is more slip-folded
in these complexes in comparison to the complexes Ind-MI-
(L)L′ of group 9 metals, despite the similar (formal) electron
counts of the metal centers in these complexes (d8, 18
electrons).3 Some of these Ni-Ind complexes are also competent
precatalysts for the oligo- and polymerization of alkenes,4
alkynes,5 and PhSiH3,6 and for the hydrosilylation of olefins.4f,k,7
The interesting structural characteristics and catalytic reac-
tivities promoted by Ni-Ind compounds and the relatively
(3) For a recent review on the chemistry of group 10 metal-indenyl complexes,
see: Zargarian, D. Coord. Chem. ReV. 2002, 233-234, 157.
(4) (a) Vollmerhaus, R.; Be´langer-Garie´py, F.; Zargarian, D. Organometallics
1997, 16, 4762. (b) Dubois, M.-A.; Wang, R.; Zargarian, D.; Tian, J.;
Vollmerhaus, R.; Li, Z.; Collins, S. Organometallics 2001, 20, 663. (c)
Groux, L. F.; Zargarian, D. Organometallics 2001, 20, 3811. (d) Groux,
L. F.; Zargarian, D.; Simon, L. C.; Soares, J. B. P. J. Mol. Catal. A 2003,
193 (1-2), 51. (e) Groux, L. F.; Zargarian D. Organometallics 2003, 22,
3124. (f) Groux, L. F.; Zargarian, D. Organometallics 2003, 22, 4759. (g)
Sun, H.; Li, W.; Han, X.; Shen, Q.; Zhang, Y. J. Organomet. Chem. 2003,
688, 132. (h) Li, W.-F.; Sun, H.-M.; Shen, Q.; Zhang, Y.; Yu, K.-B.
Polyhedron 2004, 23, 1473. (i) Jimenez-Tenorio, M.; Puerta, M. C.; Salcedo,
I.; Valerga, P.; Costa, S. I.; Silva, L. C.; Gomes, P. T. Organometallics
2004, 23, 3139. (j) Sun, H. M.; Shao, Q.; Hu, D. M.; Li, W. F.; Shen, Q.;
Zhang, Y. Organometallics 2005, 24, 331. (k) Gareau, D.; Sui-Seng, C.;
Groux, L. F.; Brisse, F.; Zargarian, D. Organometallics 2005, 24, 4003.
(5) (a) Wang, R.; Be´langer-Garie´py, F.; Zargarian, D. Organometallics 1999,
18, 5548. (b) Wang, R.; Groux, L. F.; Zargarian D. Organometallics 2002,
21, 5531. (c) Wang, R.; Groux, L. F.; Zargarian, D. J. Organomet. Chem
2002, 660, 98. (d) Rivera, E.; Wang, R.; Zhu, X. X.; Zargarian, D.; Giasson,
R. J. Mol. Catal. A 2003, 204-205, 325.
Most of the studies carried out to date on Ind complexes have
focused on compounds of groups 4-9 transition metals, such
† Universite´ de Montre´al.
‡ National Research Council Canada.
(1) For Ind complexes featuring unusually large hapticities, see: (a) Bradley,
A. C.; Lobkovsky, E.; Chirik, P. J. J. Am. Chem. Soc. 2003, 125, 8110. (b)
Bradley, A. C.; Keresztes, I.; Lobkovsky, E.; Young, V. G.; Chirik, P. J.
J. Am. Chem. Soc. 2004, 126, 16937. (c) Bradley, A. C.; Lobkovsky, E.;
Keresztes, I.; Chirik, P. J. J. Am. Chem. Soc. 2005, 127, 10291.
(2) For representative reactivities of indenyl complexes see the following reports
and references therein: (a) Frankom, T. M.; Green, J. C.; Nagy, A.; Kakkar,
A. K.; Marder, T. B. Organometallics 1993, 12, 3688. (b) Gamasa, N. P.;
Gimeno, J.; Gonzalez-Bernado, C.; Martin-Vaca, B. M.; Monti, D.; Bassetti,
M. Organometallics 1996, 15, 302. (c) Foo, T.; Bergman, R. G. Organo-
metallics 1992, 11, 1801. (d) Trost, B. M.; Kulawiec, R. J. J. Am. Chem.
Soc. 1993, 115, 2027. (e) O’Connor, J. M.; Casey, C. P. Chem. ReV. 1987,
87, 307. (f) Marder, T. B.; Roe, C. D.; Milstein, D. Organometallics 1988,
7, 1451. (g) Halterman, R. L. Chem. ReV. 1992, 92, 965. (h) Hauptman,
E.; Sabo-Etienne, S.; White, P. S.; Brookhart, M.; Garner, J. M.; Fagan, P.
J.; Calabrese, J. C. J. Am. Chem. Soc. 1994, 116, 8038.
(6) (a) Fontaine, F.-G.; Kadkhodazadeh, T.; Zargarian, D. J. Chem. Soc., Chem.
Commun. 1998, 1253. (b) Fontaine, F.-G.; Zargarian, D. Organometallics
2002, 21, 401.
(7) Fontaine, F.-G.; Nguyen, R.-V.; Zargarian, D. Can. J. Chem. 2003, 81,
1299.
9
6508
J. AM. CHEM. SOC. 2006, 128, 6508-6519
10.1021/ja060747a CCC: $33.50 © 2006 American Chemical Society

New Palladium−Indenyl Complexes
A R T I C L E S
Scheme 1
unexplored chemistry of their Pd analogues8 have motivated
us to initiate a systematic study of Pd-Ind compounds in order
to elucidate the influence of the metal center on structures and
reactivities. Our initial studies showed significantly lower Ind
hapticities (more “slippage”) in the compounds (η3-5-Ind)Pd-
(PR3)Cl (R) Ph, Cy, Me, and OMe); moreover, replacing the
PR3 in these compounds by t-BuNC gave [(η1-Ind)(t-BuNC))-
Pd(µ-Cl)]2.9 Subsequently, we undertook to synthesize a new
series of complexes bearing Lewis bases other than phosphines
and isocyanides to allow a comparison of structural and
reactivity features as a function of both metal and the Lewis
base ligand.
The present contribution reports on the syntheses of the Ind-
PdII(amine) complexes (η3-5-Ind)Pd(NEt3)Cl), (η1-Ind)Pd-
(BnNH2)2Cl (Bn ) PhCH2), and (η1-Ind)Pd(py)2Cl (py )
pyridine). The subsequent reaction of these complexes with
phosphines has given access to new PdI-PdI complexes bearing
a bridging indenyl ligand, i.e., (µ,η3-Ind)(µ-Cl)Pd2(PR3)2 (R )
Ph, Cy). Several dinuclear PdI-PdI complexes featuring µ-allyl
or µ-cyclopentadienyl ligands are known,10 whereas [(µ,η3-Ind)-
Pd(CNR)]2 represent the only µ-Ind complexes reported
previously.8c,d
and isocyanide complexes (η-Ind)Pd(PR3)Cl (2) and [(η1-Ind)-
(t-BuNC))Pd(µ-Cl)]2 (Scheme 1)9a was used to prepare the target
amino complexes. Thus, stirring a suspension of 111 in benzene
with NEt3 gave the complex (η-Ind)Pd(NEt3)Cl (3), whereas
the analogous reactions with BnNH2 and py gave the η1-Ind
complexes (η1-Ind)Pd(BnNH2)2Cl (4) and (η1-Ind)Pd(py)2Cl (5),
respectively (Scheme 1). The new complexes were isolated in
70-75% yields as brown (3) or yellow-brown (4 and 5) solids;
the latter compounds were also prepared in ca. 85% yield via
the reaction of 3 with 1 or 2 equiv of BnNH2 or py (Scheme
1). All three complexes are thermally stable and can be handled
in air, both in the solid state and in solution, without appreciable
decomposition. Their identities were deduced from their NMR
spectra and confirmed by the results of elemental analyses and
single-crystal X-ray diffraction studies, as described below.
Characterization of 3-5 by NMR. The ambient-temperature
1H NMR spectrum of (η-Ind)Pd(NEt3)Cl (3) displayed relatively
broad signals for all Ind protons, but a better resolution was
1
obtained at -10 °C. The assignment of the H and 13C {1H}
NMR spectra was facilitated by selective homodecoupling,
inverse-gated decoupling, COSY, and HMQC experiments. The
selective 1D NOESY experiment correlated the methylene
groups of NEt3 with H3 and H4 at 4.61 and 6.45 ppm,
respectively (see Figure 2 for the numbering scheme). Moreover,
the high resolution of the 1H NMR spectrum of 3 allowed us to
observe the detailed multiplicities of these signals and to
determine the various H-H coupling constants, as follows:
Results and Discussion
Reaction of the Dimer [(η3-Ind)Pd(µ-Cl)]2 (1) with Amines.
The synthetic route developed for the preparation of phosphine
(8) To our knowledge, the following are the only Pd-Ind compounds reported
prior to our studies: [(η3-Ind)Pd(µ-Cl)]2,8a,b [(µ,η3-Ind)Pd(CNR)]2 (R )
t-Bu, 2,6-(CH3)2C6H3; 2,4,6-(CH3)3C6H2; 2,4,6-(t-Bu)3C6H2),8c,d (η3-Ind)-
3
4
4
4
3JH1-H2 ≈ JH2-H3 ≈ JH1-H3 ≈ 2.4 Hz; JH1-H7 ≈ JH3-H4
≈
5
5
0.8 Hz; JH3-H5 ≈ JH1-H6 ≈ 1.2 Hz.
Pd(PMe3)(CH(SiMe3)2),8e,f and [(η3-Ind)PdL2]+ (L2 ) bipy, tmeda).8g,h
A
Overall, the chemical shifts and the multiplicities of the
signals for the Ind protons in 3 follow a pattern commonly
observed for the previously studied (η-Ind)Pd(PR3)Cl ana-
logues.9 For instance, the signals for H1 (5.59 ppm) and H3
(4.61 ppm) are both strongly shielded in comparison to the other
Ind signals (6.31-6.93 ppm). On the other hand, the 13C
chemical shifts of C1 and C3 (ca. 73 vs 82 ppm) indicate a
somewhat higher shielding for C1, which is the opposite of our
preliminary communication has also appeared on the preparation of a series
of Ind derivates from the reaction of cyclopropene and (PhCN)2PdCl2.8i
(a) Nakasuji, K.; Yamaguchi, M.; Murata, I.; Tatsumi, K.; Natamura, A.
Organometallics 1984, 3, 1257. (b) Samuel, E.; Bigorgne, M. J. Organomet.
Chem. 1969, 19, 9. (c) Tanase, T.; Nomura, T.; Yamamoto, Y.; Kobayashi,
K. J. Organomet. Chem. 1991, 410, C25. (d) Tanase, T.; Nomura, T.;
Fukushina, T.; Yamamoto, Y.; Kobayashi, K. Inorg. Chem. 1993, 32, 4578.
(e) Alias, F. M.; Belderrain, T. R.; Paneque, M.; Poveda, M. L.; Carmona,
E. Organometallics 1998, 17, 5620. (f) Alias, F. M.; Belderrain, T. R.;
Carmona, E.; Graiff, C.; Paneque, M.; Poveda, M. L. J. Organomet. Chem.
1999, 577, 316. (g) Vicente, J.; Abad, J.-A.; Bergs, R.; Jones, P. G.; De
Arellano, M. C. R. Organometallics 1996, 15, 1422. (h) Vicente, J.; Abad,
J.-A.; Bergs, R.; De Arellano, M. C. R.; Martinez-Vivente, E.; Jones, P.
G. Organometallics 2000, 19, 5597. (i) Fiato, R. A.; Mushak, P.; Battiste,
M. A. Chem. Commun. 1975, 869.
(10) For reviews on Pd(I)-Pd(I) compounds, see: (a) Murahashi, T.; Kurosawa,
H. Coord. Chem. ReV. 2002, 231, 207. (b) Werner, AdV. Organomet. Chem.
1981, 19, 155.
(11) For the original synthesis of this dimeric compound see refs 8a,b above.
For a revised synthesis see ref 9a.
(9) (a) Sui-Seng, C.; Enright, G. D.; Zargarian, D. Organometallics 2004, 23,
1236. (b) Sui-Seng, C.; Groux, L. F.; Zargarian, D. Organometallics 2006,
25, 571.
9
J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006 6509

A R T I C L E S
Sui-Seng et al.
Figure 1. (a) 400 MHz 1H NMR spectrum of complex 4 in C6D6, showing the four multiplets of the CH2NH2 protons (*, impurities). (b) 1H NMR spectrum
of complex 4 in C6D6/D2O.
previous observations for Ni- and Pd-Ind complexes bearing
phosphines. For example, the chemical shifts of these nuclei in
(η-Ind)Pd(PR3)Cl are in the range of 94-113 ppm for C1 and
70-80 ppm for C3, indicating that the hybridization is more
sp2-like at C1 and more sp3-like at C3; we have argued that
these observations are consistent with the larger trans influence
of PR3 versus Cl.9a Accordingly, we attribute the observation
of a more shielded C1 in 3 to a more sp3-like hybridization at
C1 arising from the weaker trans influence of NEt3 versus Cl.
The latter phenomenon is reflected in the solid-state structure
of this complex, which shows that Pd-C1 < Pd-C3 (vide
infra), but the fairly downfield chemical shift of H1 (ca. 5.6
ppm) is not consistent with sp3 C1.
are shown in Figures 2 and 3, respectively. The overall geometry
is approximately square planar in complex 3, with the largest
distortion arising from the small C1-Pd-C3 angle of 62°. The
Pd-N distance of 2.225(2) Å is in the range of Pd-N bond
lengths reported to date for Pd-NEt3 complexes.14 The fairly
long Pd-C3a and Pd-C7a distances indicate that the Ind-Pd
interaction is primarily through the allylic carbons C1, C2, and
C3. The significant difference in the Pd-C bond lengths is a
reflection of the so-called “slippage” of the Ind ligand, which
can be measured by calculating parameters such as the slip value
(∆M-C) and the hinge and fold angles (HA and FA).15 The
calculated values of these parameters in 3, 0.39 Å and ca. 16
and 12°, respectively, are similar to the corresponding values
in the phosphine analogues (η3-5-Ind)Pd(PR3)Cl (2) but sig-
nificantly smaller than those of [(η3-Ind)Pd(µ-Cl)]2 (1) (∆M-C
) 0.46 Å, HA ) 17°, FA ) 16°).9a On the other hand, the
significant asymmetry in the Pd-C(allyl) bond lengths (Pd-
C1 < Pd-C3) is the opposite of the trend generally observed
in phosphine complexes (Pd-C1 > Pd-C3), thus confirming
the trans influence order deduced from the NMR spectra (PR3
> Cl > NEt3).
X-ray crystal structure analyses of complexes 4 and 5 have
confirmed the trans square planar geometry around Pd (Figure
3). The structural parameters for these complexes are similar
to those found in the only other structurally characterized (η1-
Ind)Pd complex,8a as well as those of other η1-Ind compounds
reported previously.16,17 For example, the sp3-hybridized char-
acter of the Pd-bound carbon atom is reflected in the C1-C7a
(ca. 1.50 Å) and C1-C2 (ca. 1.47 Å) distances that are in the
normal range for C-C single bonds, whereas the C2-C3
1
The H and 13C{1H} NMR spectra of complexes 4 and 5
showed only one set of signals, indicating that only one isomer,
cis or trans, was obtained in each case; we have assumed that
these complexes adopt the thermodynamically more stable trans
geometry, as in bis(amine)dihalogenopalladium(II) complexes.12
The NMR data for the indenyl fragment were very similar to
those found in previously reported transition metal-η1-indenyl
complexes.8e,9a,13 In the 13C NMR spectra, for instance, the
chemical shift of C1 is significantly upfield of the corresponding
signals in η-Ind complexes 2 (40 vs 94-113 ppm). The signals
for the diastereotopic PhCH2NH2 protons in complex 4 appear
as four triplets of doublets centered at 3.84, 3.34, 2.37, and 1.61
ppm (Figure 1a). The H,H-COSY spectrum indicates that these
signals form an ABCD spin system. The vicinal and geminal
coupling constants were estimated at ca. 3 and 12 Hz,
respectively. Unambiguous assignment of the amine protons was
achieved by adding a few drops of D2O to the NMR sample,
which caused the two multiplets observed for NH2 at 2.37 and
1.61 ppm to disappear (Figure 1b). The NH/ND exchange also
reduced the two CH2 signals to an AB doublet, and this allowed
us to determine the geminal coupling constant for these protons
(2JAB ≈ 12 Hz).
(13) (a) Casey, C. P.; O’Connor J. M Organometallics 1985, 4, 384. (b)
Hermmann, W. A.; Kuhn, F. E.; Romao, C. C. J. Organomet. Chem. 1995,
489, C56. (c) O’Hare, D. Organometallics 1987, 6, 1766.
(14) To our knowledge, only two examples of Pd-NEt3 complexes were
characterized by single-crystal X-ray crystallography: (Et3N)2PdCl2
(Timokhin, V. I.; Anastasi, N. R.; Stahl, S. S. J. Am. Chem. Soc. 2003,
125, 12996) and [Pd(dmpe)(Me)(NEt3)][BPh4] (Seligson, A. L.; Trogler,
W. C. J. Am. Chem. Soc. 1991, 113, 2520).
(15) ∆M-C ) 0.5 {(M-C3a + M-C7a) - 0.5 {(M-C1 + M-C3). HA is
the angle between the planes encompassing the atoms C1, C2, C3 and C1,
C3, C3a, C7a. FA is the angle between the planes encompassing the atoms
C1, C2, C3 and C3a, C4, C5, C6, C7, C7a. The ∆M-C, HA, and FA
values for a range of Ind complexes are given in the following reports: (a)
Baker, T.; Tulip, T. H. Organometallics 1986, 5, 839. (b)Westcott, S. A.;
Kakkar, A. K.; Stringer, G.; Taylor, N. J.; Marder, T. B. J. Organomet.
Chem. 1990, 394, 777. The corresponding data for group 10 complexes
are given in ref 3.
Solid-State Structures of 3-5. The X-ray analyses of 3-5
have confirmed the spectral assignments and provided valuable
structural information for these first Ind-Pd complexes bearing
amine ligands. The crystal data and selected structural param-
eters are presented in Tables 1 and 2, and the ORTEP diagrams
(12) Coe, J. C.; Lyons, R. J. Inorg. Chem. 1970, 9, 1775.
9
6510 J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006

New Palladium−Indenyl Complexes
A R T I C L E S
Table 1. Crystal Data, Data Collection, and Structure Refinement Parameters of 3-5 and 6a
3
4
5
6a
formula
mol wt
C15H22N1Cl1Pd1
358.19
C23H25N2Cl1Pd1.0.5C6H6
510.35
C19H17N2Cl1Pd1
415.20
C34H49N1P1Cl1Pd1
644.56
cryst color, habit
cryst dimens, mm
system
space group
a, Å
brown-orange, block
0.08 × 0.23 × 0.53
monoclinic
P21/c
8.7756(1)
13.9797(2)
12.4209(1)
90
95.397(1)
90
1517.04(3)
4
yellow, plate
0.06 × 0.15 × 0.15
triclinic
orange, block
0.19 × 0.28 × 0.38
orthorombic
Pbca
13.2654(2)
13.3187(2)
19.3102(4)
90
orange, block
0.11 × 0.15 × 0.30
triclinic
P1h
P1h
8.1918(13)
10.3940(16)
14.768(16)
83.970(3)
76.233(3)
69.495(3)
1143.6(3)
2
10.3658(1)
12.3444(1)
14.4307(2)
91.696(1)
109.563(1)
100.612(1)
1701.87(3)
2
b, Å
c, Å
R, deg
â, deg
90
90
γ, deg
volume, Å3
Z
3411.69(10)
8
1.617
Bruker AXS, SMART 2K
100
1.54178
10.201
ω scan
1664
D(calcd), g cm-1
diffractometer
temp, K
λ, Å
1.568
1.482
1.258
Bruker AXS, SMART 2K
100
1.54178
11.331
ω scan
728
Bruker AXS, SMART 1K
125
0.71073
0.943
ω scan
522
Bruker AXS, SMART 2K
100
1.54178
5.709
ω scan
676
µ, mm-1
scan type
F(000)
θ
max, deg
h,k,l range
72.91
29.22
72.92
72.85
-10 e h e 10
-17 e k e 17
-15 e l e 14
18428/3002
multiscan
SADABS
0.16, 0.56
0.0280, 0.0735
1.043
-11 e h e 11
-14 e k e 14
-20 e l e 20
14017/6119
multiscan
SADABS
0.86, 0.94
0.0370, 0.0951
1.053
-16 e h e 15
-15 e k e 16
-23 e l e 23
26119/3389
multiscan
SADABS
0.09, 0.31
0.0470, 0.1275
0.967
-12 e h e 12
-14 e k e 15
-17 e l e 17
20599/6482
multiscan
SADABS
0.43, 0.64
0.0478, 0.1459
1.139
no. of reflns collected/unique
absorption
correction
T (min, max)
R [F 2 > 2σ(F 2)], Rw(F 2)
GOF
Table 2. Selected Bond Distances (Å) and Angles (deg) for 3-5 and 6a
3
4
5
6a
(X
)
N, Y
)
C3)
(X
)
N1, Y
)
N3)
(X
)
N1, Y
)
N2)
(X ) N, Y ) P)
Pd-X
2.1674(18)
2.3598(5)
2.225(2)
2.151(2)
2.171(2)
2.608(2)
2.548(2)
1.403(4)
1.406(3)
1.474(3)
1.422(3)
1.480(3)
1.383(4)
1.396(3)
1.386(4)
1.399(4)
1.385(3)
2.066(3)
2.061(3)
2.031(4)
2.129(3)
Pd-Cl
2.3996(8)
2.066(2)
2.086(3)
2.479(4)
2.036(4)
2.054(10)
2.278(4)
2.3812(9)
2.2752(9)
2.110(4)
Pd-Y
Pd-C1
Pd-C2
Pd-C3a
Pd-C7a
C1-C2
C2-C3
C3-C3a
C3a-C7a
C7a-C1
C3a-C4
C4-C5
C5-C6
C6-C7
C7-C7a
2.145(12)
1.473(4)
1.352(5)
1.457(4)
1.414(4)
1.482(4)
1.394(4)
1.386(5)
1.396(5)
1.390(5)
1.390(4)
1.465(12)
1.35(2)
1.45(2)
1.423(10)
1.493(14)
1.341(13)
1.465(12)
1.372(13)
1.40(2)
1.481(14)
1.35(3)
1.37(5)
1.490(5)
1.359(6)
1.456(6)
1.426(5)
1.472(5)
1.391(5)
1.387(6)
1.408(7)
1.395(6)
1.395(5)
1.43(3)
1.494(14)
1.360(14)
1.461(15)
1.362(16)
1.41(2)
1.39(2)
1.41(2)
X-Pd-Cl
C1-Pd-X
C1-Pd-Y
Cl-Pd-Y
C3-Pd-N
C1-Pd-Cl
93.19(5)
166.93(8)
62.32(9)
159.79(7)
106.42(8)
97.61(7)
92.39(11)
87.11(14)
91.6(1)
81.32(18)
98.2(2)
91.23(14)
91.9(3)
89.2(3)
86.67(14)
91.0(3)
88.9(3)
82.84(9)
89.84(14)
95.15(11)
92.22(3)
88.91(7)
87.90(15)
93.27(16)
∆M-C (Å)a
HA (deg)b
FA (deg)c
0.39
16.46
12.71
a ∆M-C ) 0.5(M-C3a + M-C7a) - 0.5(M-C1 + M-C3). b Angle formed between the planes formed by the atoms C1, C2, C3 and C1, C3, C3a,
C7a. c Angle formed between the planes formed by the atoms C1, C2, C3 and C3a C4, C5, C6, C7, C7a.
distance (ca. 1.35 Å) is in the expected range for a C(sp2)-
C(sp2) double bond. The Pd-N bond lengths (ca. 2.06 Å for 4
and 2.03 Å for 5) lie well within the range of distances reported
previously for analogous compounds.18 The coordinated pyridine
rings in complex 5 form a dihedral angle of ca. 15° and are
oriented nearly orthogonal to the Pd square plane, which serves,
presumably, to maximize Pdfpy back-bonding and minimize
steric interactions.
New Monometallic (η1-Ind)PdII and Bimetallic (µ,η3-Ind)-
PdI2 Complexes. That complexes featuring η3-5- or η1-Ind
9
J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006 6511

A R T I C L E S
Sui-Seng et al.
solution of 4, generated in situ by addition of 2 equiv of BnNH2
to 1. The reaction with PCy3 gave an orange-brown solution
from which we isolated an orange powder that was identified
as the mixed-ligand species (η1-Ind)Pd(PCy3)(BnNH2)Cl (6a,
Scheme 2, method A, 85% yield). The analogous reaction with
PPh3 gave (η1-Ind)Pd(PPh3)(BnNH2)Cl (6b), which was char-
acterized by NMR but could not be isolated and purified because
it decomposed to two new products that will be discussed later
(Scheme 2). Complexes 6a and 6b were also obtained by adding
1 equiv of BnNH2 to (η-Ind)Pd(PCy3)Cl (2a) or its PPh3
analogue 2b, respectively (Scheme 2, method B, ca. 78% yield
for 6a).
The new η1-Ind complexes 6 can be considered to be suitable
models for the postulated intermediate in the ligand displacement
reaction (η-Ind)M(L)Cl + L′ f (η-Ind)M(L′)Cl + L, proceeding
by an associative mechanism. It is interesting to note that
associative ligand substitutions of the closely related complexes
(η-Ind)M(L)2 of group 9 metals are believed to proceed via η3-
Ind intermediates (e.g., (η3-Ind)Ir(PMe2Ph)3).19 One possible
explanation for the apparently different behaviors of these d8
metal centers is that, in each case, the intermediate species
maintains the electronic configuration of its precursor complex;
thus, the (η1-Ind)PdII and (η3-Ind)IrI species both maintain the
(nearly) 16- and 18-electron configurations of their respective
predecessors.
Figure 2. ORTEP views of complex 3. Thermal ellipsoids are shown at
30% probability, and hydrogen atoms are omitted for clarity.
As mentioned above, after a few hours, complex 6b decom-
poses fairly rapidly to give two new products. Complex 6a was
found to have greater thermal stability, but it too decomposed
gradually (over 24 h) to give a solid residue which gave a
mixture of crystals upon recrystallization. Visual inspection of
this mixture under a microscope showed two different crystals,
orange microcrystals and larger yellow-orange crystals, which
were separated mechanically and identified by X-ray diffraction
analyses as (µ,η3-Ind)(µ-Cl)Pd2(PCy3)2 (7a) and (BnNH2)-
(PCy3)PdCl2 (8a), respectively. The products arising from the
decomposition of 6b were found to be PPh3 analogues of 7a
and 8a. In this case, recrystallization of the solid residues from
CH2Cl2/hexane did furnish pure samples of (µ,η3-Ind)(µ-Cl)-
Pd2(PPh3)2 (7b) in ca. 50% yield, but samples of the second
product, 8b, were always contaminated with 7b and could not
be obtained in pure form. We have probed the various reaction
pathways that convert 1, 2, or 6 into complexes 7 and 8, and
have examined briefly the stabilities and reactivities of the latter;
these studies are discussed next. The characterization of the new
complexes 6-8 will be discussed in the following section.
Figure 3. ORTEP views of complexes 4 and 5. Thermal ellipsoids are
shown at 30% probability, and hydrogen atoms and the solvent molecule
are omitted for clarity. The BnNH2 in 4 and the Ind and Cl ligands in 5 are
each disordered over two positions; the views shown in this figure represent
the major model.
The analogous reactions of 5 with phosphines or the reaction
of 2 with py gave complex mixtures, which were analyzed by
NMR and shown to contain the following species: 2a, (η1-
Ind)Pd(PCy3)(py)Cl, (PCy3)2PdCl2, 7a, and biindene in the PCy3
reactions; (PPh3)2PdCl2, 7b, and biindene in the PPh3 reactions.
Isolation of the products from these mixture was not pursued.
ligands can be prepared from the reaction of the common
precursor 1 with various ligands L (PR3, NEt3, t-BuNC, BnNH2,
py; Scheme 1) shows unambiguously that the nature of the
incoming ligand L has a direct bearing on Ind hapticity in the
product. To determine how the Ind hapticity would change with
a mixture of ligands, we added 2 equiv of PR3 to a CH2Cl2
(17) For a detailed discussion of η1-Ind complexes, see: Stradiotto, M.;
McGlinchey, M. J. Coord. Chem. ReV. 2001, 219-221, 311.
(18) For examples on X-ray structures of trans-bis(benzylamine)palladium(II)
complexes, see: (a) Sui-Seng, C.; Zargarian, D. Acta Crystallogr. 2003,
E59, m957. (b) Decken, A.; Pisegna, G. L.; Vogels, C. M.; Westcott, S. A.
Acta Crystallogr. 2000, C56, 1071. For examples on X-ray structures of
trans-bis(pyridine)palladium(II) complexes, see: (c) Viossat, B.; Dung, N.-
H.; Robert, F. Acta Crystallogr. 1993, C49, 84. (d) Cheshkov, D. A.;
Belyaev, B. A.; Belov, A. P.; Rybakov, V. B. Acta Crystallogr. 2004, E60,
m300.
(16) (a) Gue´rin, F.; Beddie, C. L.; Stephan, D. W.; v. H. Spence, E.; Wurz, R.
Organometallics 2001, 20, 3466. (b) Deck, P. A.; Fronczek, F. R.
Organometallics 2000, 19, 327. (c) Blenkiron, P.; Enright, G. D.; Taylor,
N. J.; Carty, A. J. Organometallics 1996, 15, 2855. (d) Thorn, M. G.;
Fanwick, P. E.; Chesnut, R. W.; Rothwell, I. P. Chem. Commun. 1999,
2543. (e) Radius, U.; Sundermeyer, J.; Peters, K.; v. Schering, H. G. Z.
Anorg. Allg. Chem. 2002, 628, 1226.
(19) Merola, J. S.; Kacmarcik, R. T.; Van Engen, D. J. Am. Chem. Soc. 1986,
108, 329.
9
6512 J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006

New Palladium−Indenyl Complexes
A R T I C L E S
Scheme 2
The bimetallic (µ,η3-Ind)PdI2 compounds 7 are reminiscent
of the analogous Cp complex (µ,η3-Cp)(µ-Cl)Pd2(PiPr3)2, which
are prepared by reacting CpPd(PiPr3)Cl with the reducing agent
Mg, the hydrides LiAlH4 or NaBH4, or the alkylating agent
n-BuMgBr.20 By analogy to the latter route, we reacted 2a and
2b with 0.5 equiv of BuLi in NMR-scale reactions to test
Scheme 3
1
whether bimetallic 7 could be obtained in this way. The H
NMR spectra of these reactions contained the expected signals
for 7, in addition to signals attributed to 1-butene and free indene
(Scheme 2, method C). Monitoring the reaction by 31P{1H}
NMR spectroscopy showed the appearance, during the initial
stages of the reaction, of new signals at ca. δ 49 (PCy3 species)
and 41 ppm (PPh3 species), followed by a gradual disappearance
of these signals and the emergence of the corresponding signals
for 7. We propose that these species are PdII-Bu intermediates
whose decomposition by â-H elimination gives 1-butene and
PdII-H species. The latter are not detected due to a rapid
reductive elimination that generates free indene and Pd0(PR3)n
species. The formation of 7 likely proceeds by a compropor-
tionation reaction between the in situ-generated Pd0 species and
the PdII precursors 2 (Scheme 3). It is noteworthy that direct
comproportionation reactions between organopalladium(II) and
Pd0 species have been used to prepare many different PdI
species, including dipalladium(I) compounds featuring (µ,η3-
Cp) and (µ,η3-allyl) ligands.10 Accordingly, we found that a
direct reaction between Pd(PPh3)4 and 1 or 2b gives 7b (Scheme
2, method D), thus confirming that a comproportionation
reaction can lead to analogous (µ,η3-Ind) compounds.
(8) and the bis(η1-Ind) complexes (η1-Ind)2Pd(PR3)(BnNH2)
(step a). The latter decompose via reductive elimination to give
1,1′-biindene (Ind-Ind) and Pd0(PR3)n(BnNH2)m (step b). A
comproportionation reaction between the latter and 6 generates
the (µ,η3-Ind)PdI2 species 7 (step c). The side product Ind-Ind
1
has been detected in the reaction mixtures by H NMR of the
solutions of 6 (over 24 h), and GC/MS analyses have confirmed
its presence (M•+ at m/z 230). Moreover, some of this side
product gets dehydrogenated to trans-1,1′-bis(indenylidene)
(InddInd),21 which cocrystallized with 7a (vide infra). We
speculate that this dehydrogenation proceeds by addition of the
benzylic C-H bond of Ind-Ind to the in situ-generated Pd0
species to give (η1-(1-Ind-Ind))Pd(H)(PR3)(BnNH2) (step d).
â-H elimination of the latter generates InddInd and a bis-
(hydrido) species (step e) that regenerates the original Pd0
species by eliminating H2 (step f, Scheme 4).
Solid samples of the µ,η3-Ind compounds 7 can be handled
in air indefinitely, but in solution they undergo a gradual and
irreversible transformation (over several weeks) into the cor-
The above observations allow us to rationalize the unantici-
pated formation of 7 and 8 from 6 via the sequence of steps
shown in Scheme 4. First, 6 undergoes a ligand redistribution
process to give the bis(chloro) compounds (BnNH2)(PR3)PdCl2
(21) Strictly speaking, the designation of trans-1,1′-bis(indenylidene) as Indd
Ind is not consistent with the definition of Ind as the indenyl radical C9H7,
but this designation has been adopted for its simplicity and intuitive appeal.
(20) Felkin, H.; Turner, G. K. J. Organomet. Chem. 1977, 129, 429.
9
J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006 6513

A R T I C L E S
Scheme 4
Sui-Seng et al.
responding monomeric PdII-phosphine species (η-Ind)Pd(PR3)-
Cl (2). This observation seemed to indicate that complexes 7
behave as if they are simple combinations of the PdII compounds
2 and the Pd0(PR3) fragment, rather than “real” dipalladium(I)
species. Indeed, our preliminary results indicate that complexes
7 demonstrate reactivities virtually identical to those of 2. For
instance, reacting 7b with AgBF4 results in the formation of
some black Pd residues and the monomeric complex [(η-Ind)-
Pd(PPh3)2][BF4] in 46% isolated yield; the latter compound is
also obtained from the reaction of (η-Ind)Pd(PPh3)Cl (2b) with
AgBF4 (Scheme 2).9b Similarly, reacting MeMgCl with either
7b or 2b gives the same product, namely (η-Ind)Pd(PPh3)Me.9b
It appears, therefore, that the comproportionation reaction that
generates complexes 7 can proceed in the reverse sense
(disproportionation) to give complexes 2 and Pd0(PR3)n.
Characterization of Complexes 6-8. Complexes 6a, 7a,
7b, and 8a were characterized by NMR spectroscopy, elemental
analyses (except for 8a), and single-crystal X-ray diffraction
studies, whereas complexes 6b and 8b were identified by
comparing their NMR spectra to those of their fully character-
ized PCy3 analogues.
a distorted square planar geometry (e.g., Cl1-Pd-Cl2 ≈ 176°)
and the Pd-N and Pd-P distances are very close to those
observed for complex 6a.
The decomposition of 6 to new compounds was indicated
by the appearance in the 31P{1H} NMR spectrum of new signals
at δ 38.5 (7a), 25.7 (7b), 44.1 (8a), and 28.6 (8b). The spectral
1
patterns observed in the H and 13C{1H} NMR spectra of the
The ambient-temperature NMR spectra of 6a and 6b gave
indications of a slow exchange process. For example, the 31P-
{1H} NMR spectra showed a broad singlet at 41.5 and 37.1
Figure 4. ORTEP view of complex 6a. Thermal ellipsoids are shown at
30% probability, and hydrogen atoms are omitted for clarity.
1
ppm, respectively; similarly, some of the H and 13C NMR
signals were broadened and some were missing. Cooling the
NMR sample to -10 °C resulted in the sharpening of the 31P
1
signals and the emergence in the H and 13C NMR spectra of
new signals due to the PCy3, BnNH2, and η1-Ind ligands (e.g.,
3
δH1 ) 4.94 ppm for 6a (d, JH-P ) 5.4 Hz) and 4.47 ppm for
3
6b (d, JH-P ) 7.6 Hz); δC1 ) 38.9 ppm for 6a and 46.6 ppm
for 6b).
X-ray diffraction studies helped establish the identity of 6a
unambiguously. The ORTEP diagram for 6a is shown in Figure
4, while Tables 1 and 2 list the crystallographic data and selected
bond distances and angles. The essentially square planar
geometry adopted by the Pd center in 6a shows a slight
tetrahedral distortion (e.g., C1-Pd-Cl ≈ 172°), which serves,
presumably, to minimize steric interactions between the Ind and
PCy3 ligands. The Pd-N distance is much longer than the
corresponding distance in 4, presumably because of the much
greater trans influence of PCy3 versus BnNH2. All the other
distances and angles are comparable to those found in the η1-
Ind complexes 4 and 5. Similarly, in the X-ray molecular
structure of complex 8a (Table 1, Figure 5), the Pd center adopts
Figure 5. ORTEP view of complex 8a. Thermal ellipsoids are shown at
30% probability, and hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg): Pd-Cl1 ) 2.2951(5), Pd-Cl2 ) 2.3068(5),
Pd-N ) 2.126(2), Pd-P ) 2.2665(5), N-C1 ) 1.489(3), P-Pd-Cl1 )
91.08(2), Cl1-Pd-N ) 86.97(5), N-Pd-Cl2 ) 88.85(5), Cl2-Pd-P )
93.09(2).
9
6514 J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006

New Palladium−Indenyl Complexes
A R T I C L E S
The diamagnetism of these d9 complexes implies a Pd-Pd bond,
which is reflected in the relatively short bond distance of ca.
2.60 Å; this is similar to analogous distances of 2.61-2.72 Å
found in (µ-allyl)(µ-X)Pd(PPh3)2 (X ) Cl,23 I,24 Cp,25 allyl26)
and lies within the expected range of 2.53-2.70 Å for PdI-PdI
bond distances found in a large number of compounds.27 As
was alluded to above, H4 and H7 are fairly close to one of the
Ph rings of the PPh3 ligand in 7b,28 which helps explain the
unusually upfield signals of these protons in the 1NMR spectrum
of 7b (vide supra).
The most notable feature of these complexes is the unusual
bonding mode of the indenyl moiety: although there are many
precedents for complexes featuring µ-allyl or µ-Cp ligands on
a PdI-PdI framework,10 the only precedents for the analogous
µ,η3-Ind complexes are the compounds [(µ,η3-Ind)Pd(CNR)]2
(R ) t-Bu; 2,6-(CH3)2C6H3; 2,4,6-(CH3)3C6H2; 2,4,6-(t-
Bu)3C6H2)).8c,d The µ,η3-Ind ligands in 7a and 7b are sym-
metrically bonded to the two PdI centers and show Pd-C
distances identical to those observed in the [(µ,η3-Ind)Pd(CNR)]2
analogues (Pd1-C1 ≈ Pd2-C3 ≈ 2.1 Å and Pd1-C2 ≈ Pd2-
C2 ≈ 2.4 Å). The relatively long Pd1-C7a and Pd2-C3a
distances of ca. 2.9 Å are out of the normal bonding range and
support the trihapto designation. Indeed, the ∆M-C values
observed for 7a and 7b (0.83 and 0.87 Å, respectively; Table
4) are in the same range as those found previously in η3-Ind
complexes29 and much larger than those of the previously
described monomeric (η3-5-Ind)PdII complexes 2. On the other
hand, the hinge and fold angles in 7 are fairly small, representing
only small planar distortions for the Ind ligands (7a, HA ≈ 6°,
FA ≈ 12°; 7b, HA ≈ 2°, FA ≈ 5°).
Figure 6. ORTEP views of complexes 7a and 7b. Thermal ellipsoids are
shown at 30% probability, and hydrogen atoms are omitted for clarity.
µ,η3-Ind moiety in 7a and 7b were very different from those of
(η-Ind)Pd(PR3)Cl complexes, but quite similar to the corre-
sponding signals of the previously studied complexes [(µ,η3-
Ind)Pd(CNR)]2.8c,d For instance, a set of signals corresponding
to an AX2 system was observed for H2 (4.22 ppm, quintuplet,
Another interesting feature of the crystal structure in complex
7a is the presence of a cocrystallized half-molecule of trans-
1,1′-bis(indenylidene) (Figure 6). The two Ind moieties in this
molecule are linked by a double bond (C81dC81i)30 involving
a trans configuration imposed by the inversion center. The
distances and angles are comparable to those obtained for the
recently published structure of trans-1,1′-bis(indenylidene).31 As
mentioned earlier, we believe that this side product arises from
the Pd0-catalyzed dehydrogenation of Ind-Ind, which is gener-
ated in situ during the formation of 7.
3
3JH-H ) JH-P ) 3.6 Hz) and H1/H3 (triplets of doublets at δ
3
3
5.81 ppm (7a) and 5.12 ppm (7b), JH-P ) 7.3 Hz, JH-H
)
)
3.6 Hz),22 while H4-H7 displayed an A2B2 system (δH4,7
7.04 ppm and δH5,6 ) 7.35 ppm for 7a; δH4-7 ) 6.52 ppm and
δH5-6 ) 5.98 ppm for 7b). This segment of the 1H NMR
spectrum for 7b is shown in Figure 7. It should be noted that
the chemical shifts for H4 and H7 in complex 7b are much
more upfield than those of H5 and H6, while the opposite trend
is observed in 7a. Inspection of the solid structure of 7b has
shown that H4 and H7 are fairly close to the center of one of
the PPh3 phenyl rings (vide infra), which indicates that the
upfield shifts are likely caused by the anisotropy cone of the
Ph rings. The 13C{1H} NMR spectra showed only five reso-
nances, assigned to the four symmetry-related pairs of carbons
C1/C3, C5/C6, C4/C7, C3a/C7a and C2; the assignments were
facilitated by the HMQC spectra.
The X-ray molecular structures obtained for 7a and 7b are
consistent with the NMR spectra observed in solution. The
ORTEP diagrams for these compounds are shown in Figure 6,
and the crystallographic data and selected bond distances and
angles are listed in Tables 3 and 4. The coordination geometry
around the Pd atoms in both complexes is square planar,
displaying angular distortions of 5-30°. The structures consist
of two PdI centers coordinated by a terminal phosphine ligand
(Pd-P ≈ 2.26-2.29 Å) and bridged by a µ,η3-Ind and a µ-Cl.
(23) Sieller, J.; Svensson, A.; Lindqvist, O. J. Organomet. Chem. 1987, 320,
129.
(24) Kobayashi, Y.; Iataka, Y.; Yamazaki, H. Acta Crystallogr. 1972, B28, 899.
(25) (a) Werner, H.; Kuhn, A.; Tune, D. J. Kruger, C.; Brauer, D. J.; Sekutowski,
J. C.; Tsay, Y.-H. Chem. Ber. 1977, 110, 1763. (b) Werner, H.; Tune, D.;
Parker, G.; Kruger, C.; Brauer, D. J. Angew. Chem., Int. Ed. Engl. 1975,
14, 185.
(26) Jolly, P. W.; Kruger, C.; Schick, K.-P.; Wilke, G. Z. Naturforsch. 1985,
35b, 926.
(27) (a) Yamamoto, Y.; Yamakazi, H. Bull. Chem. Soc. Jpn. 1985, 58, 1843.
(b) Yamamoto, Y.; Yamakazi, H. Inorg. Chem. 1986, 25, 3327. (c)
Holloway, R. G.; Penfold, B. R.; Colton, R.; McCormich, M. J. J. Chem.
Soc., Chem. Commun. 1976, 485. (d) Kullberg, M. L.; Lemke, F. R.; Powell,
D. R.; Kubiak, C. P. Inorg. Chem. 1985, 24, 3589.
(28) The distance from H4 to the Ph group (C41-C42-C43-C44-C45-C46)
is 2.771 Å, and that from H7 to the Ph group (C11-C12-C13-C14-
C15-C16) is 3.347 Å. By comparison, the distance from H1 to the Ph
group (C21-C22-C23-C24-C25-C26) is 3.511 Å, and that from H3
to the Ph group (C41-C42-C43-C44-C45-C46) is 3.968 Å. Protons
H5 and H6 are too far from the closest Ph group (>4 Å).
(29) Examples include (η5-Ind)(η3-Ind)W(CO)2 (∆M-C ) 0.07 and 0.72 Å)
(Nesmeyanov, A. W.; Ustynyuk, N. A.; Makarova, L. G.; Andrianov, V.
G.; Struchkov, Y. T.; Andrae, S.; Ustynyuk, Y. A.; Malyugina, S. G. J.
Organomet. Chem. 1978, 159, 189) and (η3-Ind)Ir(PMe3)3 (∆M-C ) 0.79
Å) (ref 19). For detailed discussions of Ind hapticity, see refs 15a,b.
(30) Symmetry code: (i) -x + 1, -y, -z + 2.
(22) In the 1H{31P} NMR spectra, the signal for H2 appears as a triplet (3JH-H
) 3.6 Hz), while that of H1 and H3 appears as a doublet (3JH-H ) 3.5
(31) Caparelli, M. V.; Machado, R.; De Sanctis, Y.; Arce, A. J. Acta Crystallogr.
1996, C52, 947.
Hz).
9
J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006 6515

A R T I C L E S
Sui-Seng et al.
1
Figure 7. 300 MHz H NMR spectrum of complex 7b in CDCl3 (*, trace CH2Cl2).
Table 3. Crystal Data, Data Collection, and Structure Refinement Parameters of 7a, 7b, and 8a
7a
7b
8a
formula
mol wt
C54H79ClP2Pd2
1038.36
C45H37ClP2Pd2
887.94
C25H42Cl2N1P1Pd1
564.87
cryst color, habit
cryst dimens, mm
system
space group
a, Å
orange, block
0.12 × 0.17 × 0.34
monoclinic
P21/n
17.481(3)
16.598(3)
17.740(3)
90
109.518(7)
90
4851.6(13)
4
red, block
0.29 × 0.30 × 0.51
monoclinic
Cc
13.8689(3)
14.2117(3)
19.1372(6)
90
104.345(2)
90
3654.35(16)
4
yellow, block
0.20 × 0.30 × 0.42
monoclinic
P21/c
17.0179(2)
9.4258(1)
18.1497(3)
90
115.208(1)
90
2634.09(6)
4
b, Å
c, Å
R, deg
â, deg
γ, deg
volume, Å3
Z
D(calcd), g cm-1
diffractometer
temp, K
λ, Å
1.422
1.614
1.424
Bruker AXS, Smart 2K
100
1.54178
7.363
ω scan
2168
Bruker AXS, Smart 2K
220
1.54178
9.684
ω scan
1784
Bruker AXS, Smart 2K
100
1.54178
8.201
ω scan
1176
µ, mm-1
scan type
F(000)
θ
max, deg
h,k,l range
53.43
72.95
72.84
-18 e h e 18
-17 e k e 17
-18 e l e 18
59 157/5653
multiscans
SADABS
0.08, 0.29
0.0549, 0.1253
0.976
-16 e h e 17
-17 e k e 17
-22 e l e 19
14 769/5858
multiscans
SADABS
0.06, 0.22
0.0535, 0.1369
1.041
-20 e h e 21
-11 e k e 11
-21 e l e 19
21 228/5049
multiscans
SADABS
0.19, 0.37
0.0308, 0.0798
1.039
no. of reflns collected/unique
absorption
correction
T (min, max)
R [F 2 > 2σ(F 2)], Rw(F 2)
GOF
Conclusion
Gradual decomposition of 6 in solution generates the di-
nuclear PdI compounds (µ,η3-Ind)(µ-Cl)Pd2(PR3)2 (7), displaying
a rare mode of Ind hapticity. A brief examination of the
reactivities of these new species with AgBF4 or MeMgCl has
shown that they give, respectively, the monomeric products [(η-
Ind)Pd(PPh3)2][BF4] and (η-Ind)Pd(PPh3)Me plus the (unde-
tected) fragment Pd(PR3)n. Our preliminary observations suggest
that complexes 7 are formed via a comproportionation reaction
from Ind-PdII and Pd0(PR3)n species and undergo spontaneous
disproportionation reaction to regenerate these precursors. These
results suggest that the possibility of such disproportionation
reactions occurring in other PdI-PdI complexes should be taken
into account, especially in view of the recent reports on the
catalytic reactivities exhibited by some of these complexes.32
We continue to probe further this issue, in particular, and the
chemistry of these µ,η3-Ind compounds in general.
The reaction of the dimer [(η3-Ind)Pd(µ-Cl)]2 (1) with a
variety of ligands has resulted in the formation of complexes
featuring Ind ligands of different hapticities, underlining the
influence of the auxiliary ligand(s) on the hapticity of Ind. Thus,
reaction with phosphines or NEt3 gives (η3-5-Ind)Pd(L)Cl (2
and 3), whereas BuNC, BnNH2, and pyridine give the η1-Ind
t
complexes [(η1-Ind)(t-BuNC)Pd(µ-Cl)]2 or trans-(η1-Ind)PdL2-
Cl (L ) BnNH2 (4), py (5)). On the other hand, the one-pot
reaction of 1 with a mixture of BnNH2 and the phosphine ligands
PCy3 or PPh3 gave the mixed-ligand amino and phosphine
species (η1-Ind)Pd(PR3)(BnNH2)Cl (6), which can also be
prepared by addition of BnNH2 to (η-Ind)Pd(PR3)Cl (2).
Compounds 6 serve as models for the postulated intermediates
in the associative ligand displacement reactions (η-Ind)M(L)-
Cl + L′ f (η-Ind)M(L′)Cl + L.
9
6516 J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006

New Palladium−Indenyl Complexes
A R T I C L E S
were done using SAINT.34 All structures were solved by direct methods
using SHELXS9735 and difmap synthesis using SHELXL97;36 the
refinements were done on F 2 by full-matrix least squares. All non-
hydrogen atoms were refined anisotropically, while the hydrogens
(isotropic) were constrained to the parent atom using a riding model.
The crystal data and experimental details are listed in Tables 1 and 3,
while selected bond distances and angles are listed in Tables 2 and 4.
The Ind moiety and the Cl atom in the crystal structure of 5 were
disordered over two positions, with respective occupancy factors of
0.58/0.42 and 0.61/0.39. One of the BnNH2 groups present within the
crystal structure of 4 was also disordered over two positions (0.69/
0.31). Each of the disorders was refined anisotropically using restraints
(SAME/SADI/EADP/DFIX) applied in order to improve the model.
The reported structure of 6a is based on the PLATON/SQUEEZE37
corrected data (volume of the potential solvent ) 168 Å3; improvement
of 4.1% in R1 while correcting for 41 electrons/cell).
Table 4. Selected Bond Distances (Å) and Angles (deg) for 7a
and 7b
7a
7b
Pd1-Cl
Pd1-P1
Pd1-C1
Pd1-C2
Pd2-Cl
Pd2-P2
Pd2-C2
Pd2-C3
Pd1-C7a
Pd2-C3a
Pd1-Pd2
C1-C2
2.4301(19)
2.293(2)
2.107(7)
2.425(7)
2.4207(19)
2.280(2)
2.412(7)
2.106(7)
2.988(7)
2.974(7)
2.5971(8)
1.418(10)
1.415(10)
1.496(10)
1.429(11)
1.476(10)
1.403(10)
1.379(11)
1.377(10)
1.417(10)
1.389(10)
2.411(2)
2.260(2)
2.072(7)
2.405(7)
2.432(2)
2.274(2)
2.401(8)
2.122(7)
2.929(8)
2.930(7)
2.6031(6)
1.422(11)
1.427(11)
1.480(12)
1.419(11)
1.502(11)
1.392(12)
1.400(15)
1.391(14)
1.399(14)
1.379(12)
C2-C3
C3-C3a
C3a-C7a
C7a-C1
C3a-C4
C4-C5
Synthesis of (η-Ind)Pd(NEt3)Cl (3). NEt3 (441 µL, 3.2 mmol) was
added to a stirred C6H6 suspension (30 mL) of [(η3-Ind)Pd(µ-Cl)]2 (1;
650 mg, 1.3 mmol) at room temperature. After being stirred for 2 h,
the resulting brown solution was concentrated to ca. 5 mL, and 15 mL
of hexane was added. A brown powder precipitated and was isolated
by filtration and washed with hexane (650 mg, 72%). Recrystallization
of a small portion of this solid from a C6H6/hexane solution yielded
crystals suitable for X-ray diffraction studies and elemental analysis.
1H NMR (C6D6, 400 MHz): δ 6.91 (d, 3JH-H ) 6.3 Hz, H7), 6.69 (br,
H5 and H6), 6.48 (d, 3JH-H ) 6.2 Hz, H4), 6.34 (br, H2), 5.62 (br, H1),
C5-C6
C6-C7
C7-C7a
C1-Pd1-P1
P1-Pd1-Cl
Cl-Pd1-P2
Pd2-Pd1-C1
C3-Pd2-P2
P2-Pd2-Cl
Cl-Pd2-Pd1
Pd1-Pd2-C3
Pd1-Cl-Pd2
103.1(2)
113.52(7)
57.45(5)
86.0(2)
99.9(2)
115.60(6)
57.89(5)
86.5(2)
101.5(2)
114.34(7)
57.10(5)
87.2(2)
99.5(2)
3
1
115.42(7)
57.80(5)
87.4(2)
4.68 (br, H3), 2.63-2.49 (m, CH2), 0.73 (t, JH-H ) 6.9 Hz, CH3). H
3
NMR (C7D8, 500 MHz, 263 K): δ 6.93-6.91 (dd, JH7-H6 ) 7.2 Hz,
4JH7-H1 ) 0.9 Hz, H7), 6.69 (quintuplet of doublets, JH-H ) 7.5 Hz,
3
64.74(5)
65.01(5)
5JH-H ) 1.2 Hz, H5 and H6), 6.45 (dd, 3JH4-H5 ) 7.3 Hz, 4JH4-H3 ) 0.9
∆M-C (Å)a
HA (deg)
FA (deg)
0.87
5.61
12.49
0.83
1.92
4.69
3
3
4
Hz, H4), 6.31 (t, JH-H ) 3.1 Hz, H2), 5.59 (td, JH1-H2 ) JH1-H3
)
4
3
4
2.4 Hz, JH1-H7 ) 0.7 Hz, H1), 4.61 (td, JH3-H2 ) JH3-H1 ) 2.5 Hz,
4JH3-H4 ) 0.8 Hz, H3), 2.54 (q, 3JH-H ) 6.9 Hz, CH2), 0.73 (t, 3JH-H
)
6.9 Hz, CH3). 13C{1H} NMR (CDCl3, 75 MHz): δ 139.86 (s, C3a or
C7a ), 128.50 (s, C5), 126.62 (s, C6), 119.33 (s, C7), 115.97 (s, C4),
111.22 (s, C2), 81.56 (s, C3), 72.72 (s, C1), 50.02 (s, CH2), 10.64 (s,
CH3). The missing resonance for C3a or C7a is probably obscured under
the residual solvent resonances at ca. 129 ppm. Anal. Calcd for
C15H22N1Cl1Pd1: C, 50.29; H, 6.19; N, 3.91. Found: C, 50.15; H, 6.27;
N, 3.76.
Synthesis of (η1-Ind)Pd(BnNH2)2Cl (4). Method A. Benzylamine
(127 µL, 1.2 mmol) was added to a stirred C6H6 suspension (15 mL)
of [(η3-Ind)Pd(µ-Cl)]2 (1; 150 mg, 0.29 mmol) at room temperature.
The yellow-green mixture was stirred approximately 2 h, filtered, and
evaporated to dryness to give a yellow solid which was washed with
hexane (200 mg, 73%). Recrystallization of a small portion of this solid
from a C6H6/hexane solution yielded crystals suitable for X-ray
diffraction studies.
a ∆M-C ) 0.5(Pd1-C7a + Pd2-C3a) - 0.5(Pd1-C1 + Pd2-C3).
Experimental Section
General Comments. All manipulations and experiments were
performed under inert atmosphere using standard Schlenk techniques
and/or a nitrogen-filled glovebox. Dry, oxygen-free solvents were
prepared by distillation from appropriate drying agents and employed
throughout. The syntheses of [(η3-Ind)Pd(µ-Cl)]2 (1), (η-Ind)Pd(PR3)-
Cl (2), (η-Ind)Pd(PPh3)Me, and [(η-Ind)Pd(PPh3)2][BF4] have been
reported previously;8 all other reagents used in the experiments were
obtained from commercial sources and used as received. The elemental
analyses were performed by the Laboratoire d’Analyse Ele´mentaire
(Universite´ de Montre´al). Bruker AV500, ARX400, AV400, AMX300,
and AV300 spectrometers were employed for recording 1H (500, 400,
and 300 MHz), 13C{1H} (126, 100, and 75 MHz), and 31P{1H} (202,
161, and 121 MHz) NMR spectra at ambient temperature, unless
Method B. Benzylamine (61 µL, 0.56 mmol) was added to a stirred
C6H6 solution (15 mL) of (Ind)Pd(NEt3)Cl (3; 100 mg, 0.28 mmol) at
room temperature. After being stirred for 2 h, the resulting brown-
green mixture was concentrated to ca. 5 mL. A yellow powder
precipitated and was isolated by filtration and washed with hexane (110
1
otherwise specified. The H and 13C NMR spectra were referenced to
solvent resonances, as follows: 7.26 and 77.16 ppm for CHCl3 and
CDCl3, 7.16 and 128.06 ppm for C6D5H and C6D6, 5.30 and 53.52 for
CDHCl2 and CD2Cl2, 2.11 and 21.10 for C7D7H and C7D8. The 31P
NMR spectra were referenced to 85% H3PO4 (0 ppm).
Crystal Structure Determinations. The crystal data for complexes
3, 4, 5, 6a, 7a, 7b, and 8a were collected on Bruker AXS Smart 2K
and 1K (for 4) diffractometers using SMART.33 Graphite-monochro-
mated Cu KR radiation was used at 100 K for all crystals except those
of 7b, for which the temperature was 220 K, and 4, for which the
radiation used was Mo KR at 125 K. Cell refinement and data reduction
1
3
mg, 84%). H NMR (CDCl3, 400 MHz): δ 7.64 (d, JH-H ) 7.3 Hz,
3
H4 or H7), 7.45 (d, JH-H ) 7.3 Hz, H7 or H4), 7.36-7.28 (m, Ph),
7.23 (t, 3JH-H ) 7.4 Hz, H6 or H5), 7.17 (t, 3JH-H ) 7.4 Hz, H5 or H6),
3
3
7.11-7.08 (m, Ph), 6.82 (d, JH-H ) 5.0 Hz, H3), 6.62 (dd, JH-H
)
3
3
5.0 Hz and JH-H ) 1.9 Hz, H2), 4.72 (d, JH-H ) 1.8 Hz, H1), 3.84,
3
2
3.34 (td, JH-H ) 12.4 Hz and JH-H ) 3.9 Hz, CH2), 2.37, 1.61 (brt,
(34) SAINT, Release 6.06; Integration Software for Single-Crystal Data, Bruker
AXS Inc.: Madison, WI, 1999.
(32) (a) Stambouli, J. P.; Kuwano, R.; Hartwig J. F. Angew. Chem., Int. Ed.
2002, 41, 4746. (b) Prashad, M.; Mak, X. Y.; Liu, Y.; Repic, O. J. Org.
Chem. 2003, 68, 1163. (c) Christmann, U.; Vilar, R.; White, A. J. P.;
Williams, D. J. Chem. Commun. 2004, 1294.
(33) SMART, Release 5.059; Bruker Molecular Analysis Research Tool, Bruker
AXS Inc.: Madison, WI, 1999.
(35) Sheldrick, G. M. SHELXS, Program for the solution of Crystal Structures;
University of Goettingen: Goettingen, Germany, 1997.
(36) Sheldrick, G. M. SHELXL, Program for the Refinement of Crystal
Structures; University of Goettingen: Goettingen, Germany, 1997.
(37) Spek, A. L. PLATON; University of Utrecht: Utrecht, The Netherlands,
2002.
9
J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006 6517

A R T I C L E S
Sui-Seng et al.
3JH-H ) 11.1 Hz, NH2). 1H NMR (C6D6, 400 MHz): δ 7.70 (d, 3JH-H
solid from a cold hexane solution yielded crystals suitable for X-ray
diffraction studies and elemental analysis. 1H NMR (C6D6, 400 MHz):
δ 7.35 (dd, 3JH-H ) 5.6 Hz and 4JH-H ) 3.1 Hz, H5 and H6), 7.04 (dd,
3JH-H ) 5.6 Hz and 4JH-H ) 3.1 Hz, H4 and H7), 5.81 (td, 3JH-P ) 7.3
3
) 7.3 Hz, H4 or H7), 7.40 (d, JH-H ) 7.3 Hz, H7 or H4), 7.19-7.16,
7.04-6.90 (m, Ph, H5 and H6), 6.67 (d, 3JH-H ) 5.0 Hz, H3), 6.60 (dd,
3JH-H ) 4.9 and 2.1 Hz, H2), 4.52 (br, H1) 3.68, 3.13 (td, 3JH-H ) 11.8
2
3
and JH-H ) 3.7 Hz, CH2), 2.13, 1.33 (brt, JH-H ) 10.0 Hz NH2).
13C{1H} NMR (CDCl3, 100 MHz): δ 149.62 (s, C7a or C3a), 141.72 (s,
C3a or C7a), 138.94 (s, Cipso), 138.76 (s, C2), 128.97 (s, Cortho), 128.66
(s, C6 or C5) 128.22 (s, Cmeta and Cpara), 124.44 (s, C5 or C6), 123.76 (s,
C4 or C7), 121.25 (s, C7 or C4), 120.75 (s, C3), 49.44 (s, CH2), 40.08
(s, C1). Anal. Calcd for C23H25Cl1N2Pd1: C, 58.61; H, 5.35; N, 5.94.
Found: C, 59.04; H, 5.28; N, 5.37.
Hz and 3JH-H ) 3.8 Hz, H1 and H3), 4.22 (quintuplet, 3JH-H ) 3JH-P
)
3.6 Hz, H2), 2.04-1.05 (m, PCy3). 31P{1H} NMR (C6D6, 161.92 MHz):
δ 38.5 (s). 1H NMR (CD2Cl2, 500 MHz, 263 K): δ 6.97 (dd, 4JH-H
)
3.0 Hz and 3JH-H ) 5.5 Hz, H5 and H6), 6.72 (dd, 3JH-H ) 5.4 Hz and
4JH-H ) 3.1 Hz, H4 and H7), 5.44 (td, 3JH-P ) 7.2 Hz and 3JH-H ) 3.9
Hz, H1 and H3), 3.75 (quintuplet, 3JH-H ) 3JH-P ) 3.5 Hz, H2), 2.01-
0.83 (m, PCy3). 13C{1H} NMR (CD2Cl2, 126 MHz, 263 K): δ 145.68
(s, C7a and C3a), 122.84 (s, C4 and C7), 121.82 (s, C5 and C6), 71.19 (s,
Synthesis of (η1-Ind)Pd(Py)2Cl (5). Method A. Pyridine (82 µL,
1.0 mmol) was added to a stirred C6H6 suspension (25 mL) of [(η3-
Ind)Pd(µ-Cl)]2 (1; 130 mg, 0.25 mmol) at room temperature. The
yellow-brown mixture was stirred for approximately 2 h, filtered, and
evaporated to dryness to give a yellow solid (160 mg, 76%).
Method B. Pyridine (207 µL, 2.6 mmol) was added to a stirred C6H6
solution (20 mL) of (Ind)Pd(NEt3)Cl (3; 460 mg, 1.3 mmol) at room
temperature. After being stirred for 3 h, the resulting brown-green
mixture was concentrated to ca. 10 mL. A yellow powder precipitated
and was isolated by filtration and washed with hexane (450 mg, 84%).
Recrystallization of a small portion of this solid from a C6H6/hexane
solution yielded crystals suitable for X-ray diffraction studies.
1
C2), 48.99 (s, C1 and C3), 34.64 (t, JC-P ) 7.6 Hz, Cipso), 30.11 (s,
C
ortho), 27.35 (s, Cmeta), 26.15 (s, Cpara). 31P{1H} NMR (CD2Cl2, 202
MHz, 263 K): δ 37.7 (s). Anal. Calcd for C45H73Cl1P2Pd2‚0.5C18H12:
C, 62.46; H, 7.67. Found: C, 62.39; H, 7.93.
Synthesis of (BnNH2)(PCy3)PdCl2 (8a). Recrystallization of (η1-
Ind)Pd(PCy3)(BnNH2)Cl (6a) in hexane gave yellow crystals, which
were identified as the complex (BnNH2)(PCy3)PdCl2 (8a) on the basis
1
of the NMR spectra and X-ray analysis. H NMR (C6D6, 300 MHz):
δ 7.40, 6.98, 6.87 (br, C6H5), 3.83 (br, CH2), 2.54-1.22 (m, NH2 and
PCy3). 31P{1H} NMR (C6D6, 121 MHz): δ 44.11 (s).
(η1-Ind)Pd(BnNH2)(PPh3)Cl (6b), (µ,η3-Ind)(µ-Cl)Pd2(PPh3)2 (7b),
and (BnNH2)(PPh3)PdCl2 (8b). NMR-scale preparation of 6b (C6D6),
either by the reaction of 1 (10 mg, 0.0019 mmol) with a mixture of
BnNH2 (4 µL, 0.0039 mmol) and PPh3 (10 mg, 0.0039 mmol) or by
the reaction of 2b (30 mg, 0.058 mmol) with BnNH2 (8 µL, 0.058
mmol), showed formation of 6b. Monitoring these samples indicated
that the initially formed 6b is gradually converted to 7b and 8b after
a few hours. All attempts at purifying the mixtures obtained from large-
scale reactions led to the isolation of pure samples of 7b only. Therefore,
7b has been characterized fully (vide infra), whereas 6b and 8b were
characterized by NMR spectra only, as described below.
3
1H NMR (CDCl3, 400 MHz): δ 8.38 (d, JH-H ) 6.9 Hz, Hortho),
3
7.45 (t, 3JH-H ) 7.6 Hz, Hpara), 7.01 (t, JH-H ) 6.9 Hz, Hmeta), 6.93-
3
3
6.72 (m, H4-7), 6.68 (dd, JH-H ) 4.1 and 1.6 Hz, H2), 6.45 (d, JH-H
) 5.1 Hz, H3), 4.77 (br, H1). 13C{1H} NMR (CDCl3, 100 MHz): δ
151.72 (s, Cortho), 150.58 (s, C7a or C3a), 142.54 (s, C3a or C7a), 137.28
(s, C2), 136.94 (s, Cpara), 124.33 (s, Cmeta), 123.55 (s, C3), 127.24, 124.93,
122.84, 120.50 (s, C4-7), 42.54 (s, C1). Anal. Calcd for C19H17Cl1N2-
Pd1‚H2O: C, 52.67; H, 4.42; N, 6.47. Found: C, 52.69; H, 3.89; N,
5.97.
Synthesis of (η1-Ind)Pd(PCy3)(BnNH2)Cl (6a). Method A. Ben-
zylamine (170 µL, 1.56 mmol) was added to a solution of [(η3-Ind)-
Pd(µ-Cl)]2 (1; 400 mg, 0.78 mmol) in CH2Cl2 (30 mL) at room
temperature. The brown mixture was stirred for 30 min, and PCy3 (436
mg, 1.56 mmol) was added. The orange-brown mixture was stirred for
approximately 1 h, filtered, and evaporated to dryness to give an orange
solid (850 mg, 85%).
6b. 1H NMR (C6D6, 300 MHz): δ 8.01-7.97 (m, PPh3), 7.48, 7.31
3
(d, JH-H ) 7.0 Hz, H4 and H7), 7.1-6.8 (m, PPh3, H5 and H6), 6.55
3
3
3
(d, JH-H ) 5.1 Hz, H3), 6.44 (d, JH-H ) 6.1 Hz, H2), 4.55 (d, JH-P
1
) 6.0 Hz, H1), 3.86, 3.38 (br, NH2), 2.53, 2.13 (br, CH2). H NMR
7D8, 126 MHz, 263 K): δ 8.00-7.96 (m, PPh3), 7.46 (d, JH-H
6.7 Hz, H4 or H7), 7.38 (d, JH-H ) 7.2 Hz, H7 or H4), 7.2-6.9 (m,
PPh3 and H5-6), 6.80 (d, 3JH-H ) 4.6 Hz, Ph and H5-6), 6.56 (d, 3JH-H
) 4.6 Hz, H3), 6.42 (d, 3JH-H ) 3.7 Hz, H2), 4.47 (d, 3JH-P ) 7.6 Hz,
H1), 3.92, 3.54, 2.28 (br, CH2), 3.28, 0.74, 0.25 (br, NH2). 13C{1H}
NMR (C7D8, 126 MHz, 263 K): δ 150.8 (s, C7a), 143.00 (s, C3a), 141.19
(s, Cipso BnNH2), 139.78 (s, C2), 135.71 (d, JC-P ) 11.3 Hz, Cortho
PPh3), 132.33 (d, JC-P ) 49.0 Hz, Cipso PPh3), 131.27 (s, Cpara PPh3),
129.34 (s, Cortho BnNH2), 129.16 (d, JC-P ) 10.4 Hz, Cmeta PPh3),
3
(C
)
3
Method B. BnNH2 (76 µL, 0.7 mmol) was added to a stirred C6H6
solution (20 mL) of (Ind)Pd(PCy3)Cl (2a; 375 mg, 0.7 mmol) at room
temperature. After being stirred for 2 h, the resulting orange solution
was evaporated to dryness, and 10 mL of hexane was added. An orange
powder precipitated and was isolated by filtration (350 mg, 78%).
Recrystallization of this solid from a cold hexane solution yielded
crystals of (η1-Ind)Pd(PCy3)(BnNH2)Cl (6a), (µ,η3-Ind)(µ-Cl)Pd2(PCy3)2
(7a), and (BnNH2)(PCy3)PdCl2 (8a) suitable for X-ray diffraction studies
and elemental analysis.
2
1
3
129.00 (s, Cmeta BnNH2), 127.93 (s, Cpara BnNH2), 124.93, 124.78,
124.30, 122.00, 121.85 (s, C3-7), 48.99 (s, CH2), 46.60 (s, C1). 1P{1H}
NMR (C6D6, 161 MHz): δ 37.1 (s). 31P{1H} NMR (C7D8, 202 MHz,
263 K): δ 37.0 (s).
1
6a. H NMR (C6D6, 300 MHz): δ 7.95, 7.41, 6.98, 6.82, 6.66 (br,
H
2-7), 5.03 (br, H1), 3.85 (br, CH2), 2.44-1.20 (m, NH2 and PCy3).
31P{1H} NMR (C6D6, 121 MHz): δ 41.5 (s). 1H NMR (C7D8, 500 MHz,
263 K): δ 7.96-7.94, 7.50-7.48, 7.23-6.95 (m, Ph and H4-7), 6.83
Isolation of 7b. Method A. Benzylamine (127 µL, 1.16 mmol) was
added to a solution of [(η3-Ind)Pd(µ-Cl)]2 (1; 300 mg, 0.58 mmol) in
CH2Cl2 (25 mL) at room temperature. The brown mixture was stirred
for 10 min, and PPh3 (303 mg, 1.16 mmol) was added. The resulting
brown-red mixture was stirred for approximately 1 h, filtered, and
evaporated to dryness. The orange residue was dissolved in CH2Cl2
(15 mL) and layered with hexane (10 mL) to give an orange precipitate,
which was isolated as a fine powder by filtration (250 mg, 48%).
Recrystallization of a small portion of this powder from a CHCl3/hexane
solution yielded crystals suitable for X-ray diffraction studies and
elemental analysis.
3
3
(d, JH-H ) 5.0 Hz, H2), 6.80-6.78 (m, H4-7), 6.68 (d, JH-H ) 4.9
Hz, H3), 4.94 (d, 3JH-P ) 5.4 Hz, H1), 3.82 (t, 3JH-H ) 12.9 Hz, CH2),
3.53 (s, CH2), 2.44-1.24 (m, NH2 and PCy3). 13C{1H} NMR (C7D8,
126 MHz, 263 K): δ 151.76 (s, C7a), 144.68 (s, C3a), 138.94 (s, Cipso),
129.53, 129.02, 128.83, 128.69, 128.60, 128.49, 127.82, 127.65, 127.06,
125.77, 124.84, 124.62, 123.94, 121.74, 121.69 (s, Ph and C2-7), 48.77,
1
47.26 (s, CH2), 38.85 (s, C1), 34.61 (d, JC-P ) 22.6 Hz, Cipso), 31.09
2
3
(d, JC-P ) 9.4 Hz, Cortho), 28.41 (t, JC-P ) 9.4 Hz, Cmeta), 27.48 (s,
C
para). 31P{1H} NMR (C7D8, 202 MHz, 263 K): δ 40.5 (s). Anal. Calcd
for C34H49Cl1N1Pd1: C, 63.35; H, 7.66; N, 2.17. Found: C, 63.48; H,
7.88; N, 2.05.
Synthesis of (µ,η3-Ind)(µ-Cl)Pd2(PCy3)2 (7a). After several hours
in solution, the complex (BnNH2)(PCy3)PdCl(η1-Ind) (6a) gave (µ,η3-
Ind)(µ-Cl)Pd(PCy3)2 (7a) as an orange solid. Recrystallization of this
Method B. BnNH2 (31 µL, 0.29 mmol) was added to a stirred C6H6
solution (15 mL) of (Ind)Pd(PPh3)Cl (2b; 150 mg, 0.29 mmol) at room
temperature. After being stirred for 2 h, the resulting orange solution
was evaporated to dryness, and 10 mL of hexane was added. An orange
1
powder precipitated and was isolated by filtration (70 mg, 55%). H
9
6518 J. AM. CHEM. SOC. VOL. 128, NO. 19, 2006

New Palladium−Indenyl Complexes
A R T I C L E S
NMR (CDCl3, 400 MHz): δ 7.69-7.64 (m, PPh3), 7.48-7.38 (m,
PPh3), 6.52 (dd, 3JH-H ) 5.4 Hz and 4JH-H ) 3.1 Hz, H5 and H6), 5.98
Acknowledgment. This work was made possible by financial
support provided by the Natural Sciences and Engineering
Research Council of Canada (operating grants to D.Z.) and
Universite´ de Montre´al (scholarships to C.S.-S.). We are also
indebted to Johnson Matthey for the generous loan of PdCl2,
and to Dr. M. Simard and F. Be´langer-Garie´py for their
assistance with the X-ray analyses.
3
4
3
(dd, JH-H ) 5.4 Hz and JH-H ) 3.1 Hz, H4 and H7), 5.12 (td, JH-P
3
3
) 7.7 Hz and JH-H ) 3.7 Hz, H1 and H3), 4.22 (quintuplet, JH-H
)
3.4 Hz, H2). 13C{1H} NMR (CDCl3, 100 MHz): δ 143.68 (s, C7a and
C3a), 134.69 (t, JC-P ) 7.4 Hz, Cortho), 134.62 (d, JC-P ) 43.1 Hz,
ipso), 130.29 (s, Cpara), 129.00 (t, 3JC-P ) 4.9 Hz, Cmeta), 124.09 (s, C5
2
1
C
and C6), 121.62 (s, C4 and C7), 78.36 (s, C2), 57.75 (s, C1 and C3).
31P{1H} NMR (CDCl3, 121 MHz): δ 25.7 (s). Anal. Calcd for C45H37-
Cl1P2Pd2: C, 60.86; H, 4.20. Found: C, 60.32; H, 4.13.
Supporting Information Available: X-ray crystallographic
data, in CIF format, for 3, 4, 5, 6a, 7a, 7b, and 8a. This material
is available free of charge via the Internet at http://pubs.acs.org.
Complete details of the X-ray analysis of these compounds,
including tables of crystal data, collection and refinement
parameters, bond distances and angles, anisotropic thermal
parameters, and hydrogen atoms coordinates, have been depos-
ited at the Cambridge Crystallographic Data Centre (CCDC
296295-296301). These data can be obtained free of charge
via www.ccdc.cam.ac.uk/data_request/cif, by emailing
data_request@ccdc.cam.ac.uk, or by contacting the Cambridge
Crystallographic Data Centre, 12, Union Rd., Cambridge CB2
1EZ, UK; fax +44 1223 336033.
1
8b. H NMR (C6D6, 300 MHz): δ 7.73-7.27 (m, C6H5), 4.13 (br,
CH2), 3.02 (br, NH2). 31P{1H} NMR (C6D6, 121 MHz): δ 28.59 (s).
Reaction of Complex 7b with AgBF4. A mixture of (µ,η3-Ind)(µ-
Cl)Pd2(PPh3)2 (7b; 140 mg, 0.16 mmol) and AgBF4 (31 mg, 0.16 mmol)
was stirred in CH2Cl2 (20 mL) for 2 h at room temperature and filtered
to remove AgCl. Concentration of the filtrate to ca. 5 mL, followed by
addition of ca. 15 mL of Et2O, gave [(η-Ind)Pd(PPh3)2]BF4 as an orange
precipitate, which was isolated by filtration (60 mg, 46%).
Reaction of Complex 7b with MeMgCl. This reaction was
monitored by spectroscopy, without isolating the resulting products. A
solution of MeMgCl (4 µL of a 3 M solution in THF) was added at
room temperature to a 1 mL C6D6 solution of (µ,η3-Ind)(µ-Cl)Pd2(PPh3)2
(7b; 10 mg, 0.011 mmol) in an NMR tube. The NMR spectra of this
sample showed the complete conversion of 7b to (η-Ind)Pd(PPh3)Me.
JA060747A
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