Ortho-Metalated Primary Amines. 6. The First Synthesis of Six-Membered Palladacycles from Primary Amines Containing Electron-Withdrawing Substituents: End of the Limiting Rules of Cope and Friedrich on Cyclopalladation of Benzyl- and Phenethylamines

Article abstract of DOI:10.1021/om030480d

When H₂N(CH₂)₂C₆H ₄OMe-4 (RNH₂) and Pd(OAc)₂ are reacted in a 2: 1 molar ratio, the complex [Pd(OAc)₂(NH₂R)₂ (1) is obtained. Complex 1 reacts with 1 equiv of Pd(OAc)₂ to give the dinuclear complex [Pd(OAc)(μ-OAc)(NH₂R)]₂ (2). When complex 2 is heated in acetonitrile at 80 °C, the ortho-metalated complex [Pd{C₆H₃(CH₂)₂NH ₂-2-OMe-5-κ²C,N}(μ-OAc)]₂ (3a) is obtained. Complex 3a is also prepared by refluxing RNH₂ and Pd(OAc)₂ in a 1:1 molar ratio in acetonitrile. Complex 3a reacts with NaBr or LiCl to afford the complexes [Pd{C₆H₃(CH ₂)₂NH₂-2-OMe-5-κ ²C,N}(μ-X)]₂ (X = Cl (3b), Br (3c)). PPh₃ splits the acetate or halide bridge in complex 3a or 3b to give LPd{C ₆H₃(CH₂)₂NH ₂-2-OMe-5-κ²C,N}X(PPh₃)] (X = OAc (4a), Cl (4b)). With other 2-(phenyl)ethylamines or the corresponding chlorhydrates, Pd(OAc)₂, and PPh₃ as starting materials (molar ratio 1:1:1), the complexes [Pd{C₆H₃(CH₂) ₂-NH₂-2-X-5-κ²C,N}Y(PPh₃)] (Y = OAc, X = Cl (5), F (6); Y = Cl, X = NO₂ (7)) have been isolated and fully characterized. These compounds include the first six-membered pallada-cycles synthesized from primary phenethylamines with electron-withdrawing substituents on the aryl ring. The crystal structures of 3a and 5 have been determined by X-ray diffraction.

Full text of DOI:10.1021/om030480d

Organometallics 2003, 22, 5513-5517
5513
Or th o-Meta la ted P r im a r y Am in es. 6.1 Th e F ir st Syn th esis
of Six-Mem ber ed P a lla d a cycles fr om P r im a r y Am in es
Con ta in in g Electr on -With d r a w in g Su bstitu en ts: En d of
th e Lim itin g Ru les of Cop e a n d F r ied r ich on
Cyclop a lla d a tion of Ben zyl- a n d P h en eth yla m in es
J ose´ Vicente,* Isabel Saura-Llamas,* and J esu´s Cuadrado
Grupo de Qu´ımica Organometa´lica, Departamento de Quı´mica Inorga´nica,
Facultad de Qu´ımica, Universidad de Murcia, Apartado 4021, E-30071 Murcia, Spain
M. Carmen Ram´ırez de Arellano*
Departamento de Quı´mica Orga´nica, Facultad de Farmacia, Universidad de Valencia,
46100 Valencia, Spain
Received J une 23, 2003
When H2N(CH2)2C6H4OMe-4 (RNH2) and Pd(OAc)2 are reacted in a 2:1 molar ratio, the
complex [Pd(OAc)2(NH2R)2] (1) is obtained. Complex 1 reacts with 1 equiv of Pd(OAc)2 to
give the dinuclear complex [Pd(OAc)(µ-OAc)(NH2R)]2 (2). When complex 2 is heated in
acetonitrile at 80 °C, the ortho-metalated complex [Pd{C6H3(CH2)2NH2-2-OMe-5-κ2C,N}(µ-
OAc)]2 (3a ) is obtained. Complex 3a is also prepared by refluxing RNH2 and Pd(OAc)2 in a
1:1 molar ratio in acetonitrile. Complex 3a reacts with NaBr or LiCl to afford the complexes
[Pd{C6H3(CH2)2NH2-2-OMe-5-κ2C,N}(µ-X)]2 (X ) Cl (3b), Br (3c)). PPh3 splits the acetate or
halide bridge in complex 3a or 3b to give [Pd{C6H3(CH2)2NH2-2-OMe-5-κ2C,N}X(PPh3)] (X
) OAc (4a ), Cl (4b)). With other 2-(phenyl)ethylamines or the corresponding chlorhydrates,
Pd(OAc)2, and PPh3 as starting materials (molar ratio 1:1:1), the complexes [Pd{C6H3(CH2)2-
NH2-2-X-5-κ2C,N}Y(PPh3)] (Y ) OAc, X ) Cl (5), F (6); Y ) Cl, X ) NO2 (7)) have been
isolated and fully characterized. These compounds include the first six-membered pallada-
cycles synthesized from primary phenethylamines with electron-withdrawing substituents
on the aryl ring. The crystal structures of 3a and 5 have been determined by X-ray diffraction.
In tr od u ction
general synthetic methods to achieve these ortho-
metalation reactions.5 In this paper, we further show
the general application of these three methods to
prepare ortho-metalated primary phenethylamines with
electron-releasing and electron-withdrawing groups on
the aromatic ring leading to complexes containing six-
membered palladacycles, infringing in some cases and
for the first time the three limiting rules of Cope and
Friedrich2 at once.
The ortho-palladation of aliphatic amines was initially
reported by Cope and Friedrich to fail (a) when primary
amines were used, (b) when electron-withdrawing sub-
stituents were present on the aromatic ring, or (c) when
a six-membered ring was to be formed.2 These rules
have been partially broken, and thus it has been proved
that primary benzylamines can be ortho-metalated3-7
even if they have electron-withdrawing groups on the
aromatic ring.4,5 Similarly, 2-phenylethylamine (phen-
ethylamine) can also be ortho-metalated, despite being
a primary amine leading to a cyclopalladated six-
membered ring complex.5 We have reported three
Resu lts a n d Discu ssion
Syn th esis of Com p lexes. When H2N(CH2)2C6H4-
OMe-4 (RNH2) and Pd(OAc)2 were reacted in a 2:1 molar
ratio, the complex [Pd(OAc)2(NH2R)2] (1) was obtained
(Scheme 1). Complex 1 reacted with 1 equiv of Pd(OAc)2
* To whom correspondence should be addressed. E-mail: jvs@um.es
(J .V.); ims@um.es (I.S.-L.); mcra@uv.es (M.C.R.d.A.). WWW: http://
www.um.es/gqo/.
(1) Part 1: ref 4. Part 2: Vicente, J .; Saura-Llamas, I.; Ram´ırez de
Arellano, M. C. J . Chem. Soc., Dalton Trans. 1995, 2529. Part 3: ref
5. Part 4: ref 6. Part 5: Vicente, J .; Saura-Llamas, I.; Gru¨nwald, C.;
Alcaraz, C.; J ones, P. G.; Bautista, D. Organometallics 2002, 21, 3587.
(2) Cope, A. C.; Friedrich, E. C. J . Am. Chem. Soc. 1968, 90, 909.
(3) Vicente, J .; Saura-Llamas, I.; J ones, P. G. J . Chem. Soc., Dalton
Trans. 1993, 3619.
(4) Vicente, J .; Saura-Llamas, I.; Palin, M. G.; J ones, P. G. J . Chem.
Soc., Dalton Trans. 1995, 2535.
(5) Vicente, J .; Saura-Llamas, I.; Palin, M. G.; J ones, P. G.; Ramı´rez
de Arellano, M. C. Organometallics 1997, 16, 826.
(6) Cockburn, B. N.; Howe, D. V.; Keating, T.; J ohnson, B. F. G.;
Lewis, J . J . Chem. Soc., Dalton Trans. 1973, 404. Baba, S.; Kawaguchi,
S. Inorg. Nucl. Chem. Lett. 1975, 11, 415. Avshu, A.; O’Sullivan, R.
D.; Parkins, A. W.; Alcock, N. W.; Countryman, R. M. J . Chem. Soc.,
Dalton Trans. 1983, 1619. Clark, P. W.; Dyke, S. F. J . Organomet.
Chem. 1985, 281, 389. Fuchita, Y.; Tsuchiya, H.; Miyafuji, A. Inorg.
Chim. Acta 1995, 233, 91. Fuchita, Y.; Yoshinaga, K.; Ikeda, Y.;
Kinoshita-Kawashima, J . J . Chem. Soc., Dalton Trans. 1997, 2495.
Albert, J .; Cadena, J . M.; Granell, J . Tetrahedron: Asymmetry 1997,
8, 991.
(7) Albert, J .; Granell, J .; Tavera, R. Polyhedron 2003, 22, 287.
10.1021/om030480d CCC: $25.00 © 2003 American Chemical Society
Publication on Web 11/21/2003

5514 Organometallics, Vol. 22, No. 26, 2003
Vicente et al.
Sch em e 1
Sch em e 2
materials [Pd(OAc)2{H2N(CH2)2C6H4F-4}2] and Pd-
(OAc)2 (method b).
to give the dinuclear complex [Pd(OAc)(µ-OAc)(NH2R)]2
(2). Complex 2 can also be prepared by reacting H2N-
(CH2)2C6H4OMe-4 and Pd(OAc)2 in a 1:1 molar ratio.
The ortho-metalated complex [Pd{C6H3(CH2)2NH2-2-
OMe-5-κ2C,N}(µ-OAc)]2 (3a ) was obtained by the three
methods we previously reported:5 by heating at 80 °C
in acetonitrile (a) H2N(CH2)2C6H4OMe-4 and Pd(OAc)2
in a 1:1 molar ratio, (b) [Pd(OAc)2(NH2R)2] (1) and Pd-
(OAc)2 in a 1:1 molar ratio, or (c) complex 2 (Scheme 1).
All these reactions occur with some decomposition to
metallic palladium. When the reaction between the free
amine and Pd(OAc)2 (molar ratio 1:1) was carried out
in acetonitrile at room temperature, complexes 1 and 2
could be isolated, if the reaction mixture was worked
up after 10 min (complex 1) or 40 min (complex 2).
Therefore, these complexes could be intermediates in
the ortho-metalation reaction. We propose for these
reactions the same mechanism that was previously
reported for primary benzylamines.5,7,8
Complex 3a reacts with NaBr or LiCl to afford the
dinuclear complexes 3b and 3c, where the bridging
acetate groups have been substituted by chloride or
bromide anions. Triphenylphosphine splits the acetate
or halide bridge in complexes 3a and 3b to give the
mononuclear complexes 4a and 4b (Scheme 1). The
reaction of complex 4b with 1 equiv of PPh3 was carried
out, and the starting material was recovered.
Ortho-palladation of H2N(CH2)2C6H4X-4 (X ) Cl, F)
can be also achieved by following method a (Scheme 2).
Although the dinuclear cyclopalladated acetato-bridged
complexes could not be isolated in pure form by frac-
tional crystallization methods, the addition of PPh3 to
solutions of the crude products led to bridge splitting,
and compounds [Pd{C6H3(CH2)2NH2-2-Cl-5-κ2C,N}(OAc)-
(PPh3)] (5) and [Pd{C6H3(CH2)2NH2-2-F-5-κ2C,N}(OAc)-
(PPh3)] (6) were obtained. Nevertheless, as H2N-
(CH2)2C6H4F-4 is air sensitive, the ortho-metalation of
this amine was better achieved using the starting
As we were successfully increasing the electron-
withdrawing nature of the para substituent on the aryl
ring, we tried to ortho-palladate NH2CH2CH2C6H4NO2-
4. As this amine is not commercially available, we used
[H3N(CH2)2C6H4NO2-4]Cl as starting material (Scheme
2). The reaction between the hydrochloride and Pd-
(OAc)2 in acetonitrile at 80 °C was not complete, and
the ortho-metalated product was contaminated with
1
[PdCl2(amine)2], as proved by H NMR. Although they
could not be separated by fractional crystallization
methods, reaction with PPh3 in acetone or CH2Cl2 led
to [PdCl2(PPh3)2] (insoluble in both solvents) and [Pd-
{C6H3(CH2)2NH2-2-NO2-5-κ2C,N}Cl(PPh3)] (7).
Str u ctu r e of Com p lexes. 1H and 13C NMR of
complex 1 indicated that only the cis or trans isomer
was obtained, because only one set of signals appeared.
We assumed a trans geometry because it must be the
thermodynamically most stable form, as proved for bis-
(amine)dihalogenopalladium(II) complexes.9 1H and 13C
NMR spectra of complex 2 showed only two signals for
the acetate methyl groups: one for the pair of bridging
acetates and another for the pair of terminal acetates.
Thus, the latter must have the same chemical environ-
ment and must adopt a trans disposition.
The crystal structure of complex 3a ‚3/8CH2Cl2 has
been determined by X-ray diffraction studies (Figure 1).
The structure shows two independent dinuclear mol-
ecules in the asymmetric unit. Each palladium center
is in a slightly distorted square-planar coordination
mode (mean deviation range of the plane 0.02-0.04 Å).
The bridging acetate groups force the two palladium
planes of each dimer to have dihedral angles of 35.0(1)
and 37.1(1)°, adopting a nonplanar open-book shape.
The chelated amino ligand forms a six-membered met-
allacycle, being the first intermediate of this type
characterized by X-ray diffraction. The six-membered
metallacycles are in a boat conformation for both
independent molecules. In the crystal, N-H‚‚‚O hydro-
(8) Kurzeev, S. A.; Kazankov, G. M.; Ryabov, A. D. Inorg. Chim.
Acta 2002, 340, 192.
(9) Coe, J . S.; Lyons, R. J . Inorg. Chem. 1970, 9, 1775.

Ortho-Metalated Primary Amines
Organometallics, Vol. 22, No. 26, 2003 5515
4.3°). Intermolecular N-H‚‚‚O hydrogen bonds are also
observed. The proposed structures for complexes 4a ,b,
6, and 7 are based on the crystal structure of complex
5 and on those of related complexes, as well as on the
P/C transphobia.
Ortho-metalation is also evident from the study of the
1H and 13C NMR spectra of complexes 3-7. The AB
system characteristic of meta and ortho aromatic pro-
tons of para-disubstituted aryl groups of the amines
changes into a set of three different signals, correspond-
ing to H(3), H(4), and H(6) of the ortho-metalated ring.
In complex 7, the H(4) and H(6) resonances are not
observed because they appear in the multiplet corre-
sponding to the phenyl groups. On the other hand, the
resonance due to carbon C(1) shifts downfield with
respect to the non-ortho-metalated group.
In conclusion, we have shown that it is possible to
cyclopalladate primary phenethylamines with electron-
withdrawing groups, infringing, for the first time, the
three limiting rules of Cope and Friedrich on cyclopal-
ladation of benzyl- and phenethylamines. This is THE
END of the issue.
F igu r e 1. Thermal ellipsoid plot (50% probability) of a
dimer of 3a , along with the labeling scheme (same labeling
scheme plus an “A” for the other dimer). Selected bond
lengths (Å) and angles (deg): Pd(1)-C(1) ) 1.969(6), Pd-
(1)-N(1) ) 2.049(5), Pd(1)-O(3) ) 2.067(4), Pd(1)-O(5) )
2.177(4), Pd(1)‚‚‚Pd(2) ) 2.9229(7), Pd(2)-C(11) ) 1.965-
(6), Pd(2)-O(6) ) 2.055(4), Pd(2)-N(2) ) 2.059(5), Pd(2)-
O(4) ) 2.185(4), Pd(1A)-C(1A) ) 1.969(6), Pd(1A)-N(1A)
) 2.052(5), Pd(1A)-O(3A) ) 2.057(4), Pd(1A)-O(5A) )
2.170(4), Pd(1A)‚‚‚Pd(2A) ) 2.9719(7), Pd(2A)-C(11A) )
1.973(6), Pd(2A)-N(2A) ) 2.037(5), Pd(2A)-O(6A) ) 2.062-
(4), Pd(2A)-O(4A) ) 2.182(4); C(1)-Pd(1)-N(1) ) 88.8(2),
C(1)-Pd(1)-O(3) ) 92.7(2), N(1)-Pd(1)-O(5) ) 89.70(17),
O(3)-Pd(1)-O(5) ) 88.49(16), C(11)-Pd(2)-O(6) ) 90.5-
(2), C(11)-Pd(2)-N(2) ) 92.3(2), O(6)-Pd(2)-O(4) ) 88.55-
(15), N(2)-Pd(2)-O(4) ) 88.10(17), C(1A)-Pd(1A)-N(1A)
) 89.8(2), C(1A)-Pd(1A)-O(3A) ) 91.4(2), N(1A)-Pd(1A)-
O(5A) ) 86.65(17), O(3A)-Pd(1A)-O(5A) ) 91.88(16),
C(11A)-Pd(2A)-N(2A) ) 91.7(2), C(11A)-Pd(2A)-O(6A)
) 89.76(19), N(2A)-Pd(2A)-O(4A) ) 85.63(17) and O(6A)-
Pd(2A)-O(4A) ) 92.17(15).
Exp er im en ta l Section
Gen er a l P r oced u r es. Infrared spectra were recorded on
Perkin-Elmer 1430 and 16F-PC-FT spectrometers. C, H, and
N analyses, conductance measurements, and melting point
determinations were carried out as described elsewhere.3,4
Unless otherwise stated, NMR spectra were recorded in CDCl3,
with Varian Unity 300 and Bruker AC-400 spectrometers.
Chemical shifts are referenced to TMS (1H and 13C{1H}) or
H3PO4 (31P{1H}). Signals in the 1H and 13C NMR spectra of
complexes 1, 3a , and 4a were assigned with the help of HSQC
and HMBC techniques. 13C{1H} NMR data for complexes 3b
and 5-7 have been included in the Supporting Information.
Reactions were carried out at room temperature without
special precautions against moisture. The molar conductivities
of all complexes in acetone are between 0 and 1 Ω-1 cm2 mol-1
,
in agreement with their nonelectrolytic nature.12 4-Methoxy-
phenethylamine, 4-chlorophenethylamine, 4-fluorophenethyl-
amine, and 4-nitrophenethylamine hydrochloride (Aldrich) and
palladium acetate (J ohnson Mattey) were used as received.
Syn th esis of [P d (OAc)2{NH2(CH2)2C6H4OMe-4}2] (1). To
a suspension of Pd(OAc)2 (307 mg, 1.37 mmol) in acetone (10
mL) was added 4-methoxyphenethylamine (0.400 mL, 2.74
mmol), and the resulting mixture was stirred for 1 h. A yellow
solid precipitated, which was filtered, washed with Et2O, and
F igu r e 2. Thermal ellipsoid plot (50% probability) of 5,
along with the labeling scheme. Selected bond lengths (Å)
and angles (deg): Pd-C(1) ) 1.998(5), Pd-O(1) ) 2.101-
(3), Pd-N(1) ) 2.111(4), Pd-P ) 2.2518(13); C(1)-Pd-
N(1) ) 84.29(17), O(1)-Pd-N(1) ) 85.68(14), C(1)-Pd-P
) 93.85(13), O(1)-Pd-P ) 96.18(9).
(10) Vicente, J .; Arcas, A.; Bautista, D.; J ones, P. G. Organometallics
1997, 16, 2127. Vicente, J .; Abad, J . A.; Frankland, A. D.; Ram´ırez de
Arellano, M. C. Chem. Eur. J . 1999, 5, 3066. Vicente, J .; Abad, J . A.;
Hernandez-Mata, F. S.; J ones, P. G. J . Am. Chem. Soc. 2002, 124, 3848.
Vicente, J .; Abad, J . A.; Mart´ınez-Viviente, E.; J ones, P. G. Organo-
metallics 2002, 21, 4454.
(11) See for example: Albert, J .; Bosque, R.; Cadena, J . M.; Delgado,
S.; Granell, J . J . Organomet. Chem. 2001, 634, 83. Carbayo, A.; Cuevas,
J . V.; Garcia Herbosa, G. J . Organomet. Chem. 2002, 658, 15.
Fernandez, S.; Navarro, R.; Urriolabeitia, E. P. J . Organomet. Chem.
2000, 602, 151. Fernandez, A.; Vazquez Garcia, D.; Fernandez, J . J .;
Lopez Torres, M.; Suarez, A.; Castro J uiz, S.; Vila, J . M. Eur. J . Inorg.
Chem. 2002, 2389. Fernandez-Rivas, C.; Cardenas, D. J .; Martin-
Matute, B.; Monge, A.; Gutierrez-Puebla, E.; Echavarren, A. M.
Organometallics 2001, 20, 2998. J alil, M. A.; Fujinami, S.; Nishikawa,
H. J . Chem. Soc., Dalton Trans. 2001, 1091. Lohner, P.; Pfeffer, M.;
Fischer, J . J . Organomet. Chem. 2000, 607, 12. Marshall, W. J .;
Grushin, V. V. Organometallics 2003, 22, 555. Amatore, C.; Bahsoun,
A. A.; J utand, A.; Meyer, G.; Ntepe, A. N.; Ricard, L. J . Am. Chem.
Soc. 2003, 125, 4212. Bartolome, C.; Espinet, P.; Vicente, L.; Villafan˜e,
F.; Charmant, J . P. H.; Orpen, A. G. Organometallics 2002, 21, 3536.
Lo´pez, C.; Caubet, A.; Pe´rez, S.; Solans, X.; Font-Bard´ıa, M. J .
Organomet. Chem. 2003, 681, 82.
gen bonds form zigzag chains parallel to the b axis (see
the Supporting Information).
The crystal structure of complex 5 (Figure 2) shows
the phosphine ligand trans to the amine group, dem-
onstrating once again the well-established tendency of
PPh3 and aryl ligands not to be trans to each other when
coordinated to palladium. We have proposed for this
destabilizing effect between pairs of trans ligands in
palladium complexes the term of transphobia.10 This
term has also been used by other authors.11 The six-
membered metallacycle in complex 5 shows a boat
conformation and a slightly distorted square-planar
geometry (N-Pd-C and Br-Pd-P dihedral angle of
(12) Geary, W. J . Coord. Chem. Rev. 1971, 7, 81.

5516 Organometallics, Vol. 22, No. 26, 2003
Vicente et al.
1
air-dried to afford complex 1. Yield: 625 mg, 87%. Mp: 156
°C. Anal. Calcd for C22H32N2O6Pd: C, 50.15; H, 6.13; N, 5.34.
Found: C, 50.04; H, 6.12; N, 5.32. 1H NMR (400 MHz): δ 1.86
(s, 3 H, MeCO2), 2.77 (quint, 2 H, CH2NH2), 2.94 (“t”, 2 H, CH2-
Ar), 3.69 (m, 2 H, NH2), 3.78 (s, 3 H, OMe), 6.84 and 7.12 (AB
4.14; N, 4,80. Found: C, 37.26; H, 4,11; N, 4.90. H NMR: δ
2.44 (m, 2 H, CH2), 2.87 (“t”, 2 H, CH2), 3.67 (s, 3 H, OMe),
4.30 (br s, 2 H, NH2), 6.41 (dd, 1 H, H4, C6H3, 3J HH ) 8.1, 4J HH
) 2.7 Hz), 6.70 (d, 1 H, H3, C6H3, 3J HH ) 8.1 Hz), 6.84 (d, 1 H,
4
H6, C6H3, J HH ) 2.7 Hz).
3
system, 4 H, C6H4, J AB ) 8.6 Hz). 13C{1H} NMR (400 MHz):
Syn th esis of [P d{C6H3(CH2)2NH2-2-OMe-5-κ2C,N}(OAc)-
(P P h 3)] (4a ). To a suspension of complex 3a (114 mg, 0.181
mmol) in CH2Cl2 (30 mL) was added solid PPh3 (95 mg, 0.36
mmol). After the mixture was stirred for 6 h, a colorless
solution formed, which was filtered through a plug of MgSO4
and concentrated to ca. 2 mL. Et2O (20 mL) was added to
precipitate a pale yellow solid, which was filtered, washed with
Et2O, and air-dried to afford complex 4a . Yield: 161 mg, 78%.
Mp: 180 °C. Anal. Calcd for C29H30NO3PPd: C, 60.27; H, 5.23;
N, 2.42. Found: C, 60.17; H, 5.23; N, 2.41. 1H NMR (400
MHz): δ 1.47 (s, 3 H, MeCO2), 2.72 (br s, 2 H, CH2NH2), 3.10
(s, 3 H, MeO), 3.16 (“t”, 2 H, CH2Ar), 4.20 (br s, 2 H, NH2),
δ 23.4 (s, MeCO2), 36.0 (s, CH2Ar), 44.8 (s, CH2NH2), 55.2 (s,
OMe), 114.1 (s, m-CH, C6H4), 129.5 (s, ipso C-CH2), 129.7 (s,
o-CH, C6H4), 158.4 (s, ipso C-OMe), 179.9 (s, MeCO2).
Syn th esis of [P d {µ-(OAc)}(OAc){NH2(CH2)2C6H4OMe-
4}]2 (2). To a suspension of Pd(OAc)2 (213 mg, 0.949 mmol) in
CH2Cl2 (25 mL) was added [Pd(OAc)2{NH2(CH2)2C6H4OMe-
4}2] (1; 501 mg, 0.951 mmol). The mixture was stirred at room
temperature for 20 h. The resulting solution was filtered
through a plug of MgSO4, the solvent removed, the residue
taken up in acetone (1 mL), and the resulting solution slowly
dropped over stirred n-pentane (40 mL). An orange solid
precipitated, which was filtered, washed with n-pentane, and
air-dried to afford complex 2. Yield: 429 mg, 59%. Mp: 67 °C.
Anal. Calcd for C26H38N2O10Pd2: C, 41.56; H, 5.10; N, 3.73.
Found: C, 41.66; H, 5.29; N, 3.88. 1H NMR: δ 1.88 (s, 3 H,
MeCO2), 1.89 (s, 3 H, MeCO2), 2.51 (m, 1 H, CH2), 2.67 (m, 1
H, CH2), 3.18 (m, 2 H, CH2), 3.71 (br s, 1 H, NH2), 3.79 (s, 3
H, OMe), 5.09 (br s, 1 H, NH2), 7.84, 7.13 (AB system, 4 H,
4
4
6.06 (dd, 1 H, H6, C6H3, J HH ) 2.5, J PH ) 5.1 Hz), 6.37 (dd,
3
4
1 H, H4, C6H3, J HH ) 8.0, J HH ) 2.5 Hz), 6.83 (d, 1 H, H3,
C6H3, 3J HH ) 8.1 Hz), 7.30-7.52 (m, 15 H, PPh3). 13C{1H} NMR
3
(400 MHz): δ 24.2 (s, MeCO2), 37.8 (d, CH2NH2, J PC ) 2.1
Hz), 42.8 (s, CH2Ar), 54.4 (s, OMe), 110.7 (s, C4, C6H3), 120.5
3
(d, C6, C6H3, J PC ) 11.5 Hz), 126.4 (s, C3, C6H3), 128.2 (d,
m-CH, PPh3, 3J PC ) 10.6 Hz), 130.2 (d, p-CH, PPh3, 4J PC ) 2.3
Hz), 130.4 (d, ipso C, PPh3, 1J PC ) 48.3 Hz), 132.5 (s, C2, C6H3),
134.5 (d, o-CH, PPh3, 2J PC ) 11.7 Hz), 146.2 (d, C1, C6H3, 2J PC
) 2.7 Hz), 155.5 (d, C5, C6H3, 4J PC ) 4.4 Hz), 178.9 (s, MeCO2).
31P{1H} NMR: δ 33.2 (s).
3
C6H4, J AB ) 8.4 Hz). 13C{1H} NMR: δ 23.0 (s, MeCO2), 23.1
(s, MeCO2), 35.4 (s, CH2), 44.8 (s, CH2), 55.3 (s, OMe), 114.1
(s, m-CH, C6H4), 129.6 (s, ipso C-CH2), 129.6 (s, o-CH, C6H4),
158.5 (s, ipso C-OMe), 179.7 (s, terminal MeCO2), 185.6 (s,
µ-MeCO2). Complex 2 can be prepared by reacting Pd(OAc)2
and the free amine in CH2Cl2 (molar ratio 1:1) with similar
yield.
Syn t h esis of [P d {C6H 3(CH 2)2NH 2-2-OMe-5-κ2C,N}(µ-
OAc)]2 (3a ). 4-Methoxyphenethylamine (0.300 mL, 2.06 mmol)
and Pd(OAc)2 (463 mg, 2.06 mmol) were refluxed in acetonitrile
(25 mL) for 4 h. The resulting suspension was filtered through
a plug of MgSO4, the solvent evaporated to dryness, and the
residue collected with acetone, filtered, and air-dried to afford
complex 3a as a dark yellow solid. Yield: 171 mg, 26%. Mp:
160 °C dec. Anal. Calcd for C22H30N2O6Pd2: C, 41.86; H, 4.79;
N, 4.44. Found: C, 41.58; H, 4.84; N, 4.08. 1H NMR (400
MHz): δ 2.02 (s, 3 H, MeCO2), 2.22 (m, 1 H, CH2NH2), 2.33
(m, 1 H, CH2NH2), 2.50 (m, 1 H, CH2Ar), 2.71 (m, 1 H, CH2-
Ar), 3.02 (br s, 1 H, NH2), 3.36 (br s, 1 H, NH2), 3.73 (s, 3 H,
Syn t h esis of [P d {C6H 3(CH 2)2NH 2-2-OMe-5-κ2C,N}Br -
(P P h 3)] (4b). Complex 4b was prepared as an yellow ocher
solid in a way similar to that for complex 4a , starting from
complex 3b (132 mg, 0.196 mmol) and solid PPh3 (103 mg,
0.392 mmol), and the mixture was stirred for 5 h. Yield: 204
mg, 87%. Mp: 155 °C. Anal. Calcd for C27H27BrNOPPd: C,
1
54.16; H, 4.55; N, 2.34. Found: C, 54.15; H, 4.41; N, 2.00. H
NMR: δ 2.77 (br s, 2 H, CH2), 3.14 (“t”, 2 H, CH2), 3.20 (s, 3
H, OMe), 3.37 (br s, 2 H, NH2), 6.06 (dd, 1H, H6, C6H3, 4J HH
)
4
3
4
2.7, J PH ) 5.4 Hz), 6.35 (dd, 1 H, H4, C6H3, J HH ) 8.1, J HH
) 2.7 Hz), 6.79 (d, 1 H, H3, C6H3, J HH ) 8.1 Hz), 7.24-7.56
3
(m, 15 H, PPh3). 31P{1H} NMR: δ 34.3 (s).
Syn th esis of [P d {C6H3(CH2)2NH2-2-Cl-5-κ2C,N}(OAc)-
(P P h 3)] (5). 4-Chlorophenethylamine (0.300 mL, 2.14 mmol)
and Pd(OAc)2 (481 mg, 2.14 mmol) were refluxed in acetonitrile
(40 mL) for 4 h. The resulting suspension was filtered through
a plug of MgSO4 and the filtrate concentrated to dryness. The
residue was dissolved in CH2Cl2 (5 mL) and an Et2O/n-hexane
mixture added (1:1, 30 mL) to precipitate a brown solid (502
mg). To a solution of this solid (100 mg, 0.156 mmol) in acetone
(10 mL) was added solid PPh3 (82 mg, 0.313 mmol). After the
mixture was stirred for 30 min, a pale yellow solid precipitated,
which was filtered, washed with Et2O, and air-dried to afford
complex 5. Yield: 84 mg, 46%. Dec pt: 155 °C. Anal. Calcd
for C28H27ClNO2PPd: C, 57.75; H, 4.67; N, 2.40. Found: C,
57.64; H, 4.65; N, 2.34. H NMR: δ 1.53 (s, 3 H, MeCO2), 2.73
(br s, 2 H, CH2), 3.17 (“t”, 2 H, CH2), 4.41 (br s, 2 H, NH2),
6.29 (dd, 1 H, H6, C6H3, J HH ) 2.1, J PH ) 4.5 Hz), 6.73 (dd,
1 H, H4, C6H3, J HH ) 8.1, J HH ) 2.0 Hz), 6.79 (d, 1 H, H3,
C6H3, 3J HH ) 8.1 Hz), 7.26-7.54 (m, 15 H, Ph). 31P{1H} NMR:
δ 32.5 (s).
3
4
OMe), 6.49 (dd, 1 H, H4, C6H3, J HH ) 8.1, J HH ) 2.6 Hz),
4
6.67 (d, 1 H, H6, C6H3, J HH ) 3 Hz), 6.71 (d, 1 H, H3, C6H3,
3J HH ) 8.1 Hz). 13C{1H} NMR (400 MHz): δ 24.4 (s, MeCO2),
39.4 (s, CH2Ar), 40.3 (s, CH2NH2), 55.1 (s, OMe), 109.5 (s, C4,
C6H3), 118.3 (s, C6, C6H3), 127.0 (s, C3, C6H3), 130.4 (s, C2,
C6H3), 137.4 (s, C1, C6H3), 155.5 (s, C5, C6H3), 181.2 (s,
MeCO2).
Syn t h esis of [P d {C6H 3(CH 2)2NH 2-2-OMe-5-κ2C,N}(µ-
Br )]2 (3b). To a suspension of complex 3a (350 mg, 0.554
mmol) in acetone (35 mL) was added solid NaBr (1140 mg,
11.08 mmol), and the mixture was stirred for 8 h. The solvent
was removed and CH2Cl2 (25 mL) added. The resulting
suspension was filtered through a plug of MgSO4 and concen-
trated to ca. 2 mL and Et2O (10 mL) added to precipitate a
yellow solid, which was filtered, washed with Et2O, and air-
dried to afford complex 3b. Yield: 285 mg, 77%. Mp: 199 °C.
Anal. Calcd for C18H24Br2N2O2Pd2: C, 32.12; H, 3.59; N, 4.16.
1
4
4
3
4
Syn t h esis of [P d {C6H 3(CH 2)2NH 2-2-F -5-κ2C,N}(OAc)-
(P P h 3)] (6). [Pd(OAc)2(NH2CH2C6H4F-4)2] (500 mg, 0.994
mmol) and Pd(OAc)2 (223 mg, 0.99 mmol) were refluxed in
acetonitrile (40 mL) for 4 h. The resulting suspension was
filtered through a plug of MgSO4 and the filtrate concentrated
to dryness. The residue was dissolved in CH2Cl2 (5 mL) and
an Et2O/n-hexane mixture (1:1, 30 mL) added to precipitate a
brown solid (340 mg). To a solution of this solid (125 mg, 0.21
mmol) in acetone (5 mL) was added solid PPh3 (108 mg, 0.41
mmol). After the mixture was stirred for 30 min, a pale yellow
solid precipitated, which was filtered, washed with Et2O, and
air-dried to afford complex 6. Yield: 68 mg, 30%. Mp: 156 °C
1
Found: C, 32.31; H, 3.50; N, 4.09. H NMR: δ 2.48 (m, 2 H,
CH2), 2.92 (“t”, 2 H, CH2), 3.64 (s, 3 H, OMe), 4.06 (br s, 2 H,
3
4
NH2), 6.38 (dd, 1 H, H4, C6H3, J HH ) 8.1, J HH ) 2.7 Hz),
6.67 (d, 1 H, H3, C6H3, 3J HH ) 8.1 Hz), 6.91 (d, 1 H, H6, C6H3,
4J HH ) 2.7 Hz).
Syn t h esis of [P d {C6H 3(CH 2)2NH 2-2-OMe-5-κ2C,N}(µ-
Cl)]2 (3c). Complex 3c was prepared as a pale yellow solid in
a way similar to that for complex 3b, starting from complex
3a (503 mg, 0.797 mmol) and solid LiCl (676 mg, 15.9 mmol).
The reaction mixture was stirred for 20 h. Yield: 300 mg, 64%.
Mp: 141 °C. Anal. Calcd for C18H24Cl2N2O2Pd2: C, 37.01; H,

Ortho-Metalated Primary Amines
Organometallics, Vol. 22, No. 26, 2003 5517
dec. Anal. Calcd for C28H27FNO2PPd: C, 59.43; H, 4.81; N,
2.46. Found: C, 59.28; H, 4.78; N, 2.50. H NMR: δ 1.52 (s, 3
X-r a y Str u ctu r e Deter m in a tion s. Crystals of 3a ‚3/8CH2-
Cl2 and 5 suitable for X-ray diffraction were measured.
Structures were solved by direct methods (3a ‚3/8CH2Cl2) or the
heavy-atom method (5). All non-hydrogen atoms were refined
anisotropically on F2 (program SHELXL-97, G. M. Sheldrick,
University of Go¨ttingen, Go¨ttingen, Germany). Hydrogen
atoms were included using a riding model or as rigid methyl
groups. In the compound 3a ‚3/8CH2Cl2, a poorly resolved
1
H, Me), 2.74 (m, 2 H, CH2), 3.19 (“t”, 2 H, CH2), 4.32 (br s, 2
H, NH2), 6.08 (ddd, 1 H, H6, 3J FH ) 7.2, 4J PH ) 4.5, 4J HH ) 2.5
3
4
Hz), 6.46 (dt, 1 H, H4, J HH ) 3J FH ) 8.4, J HH ) 2.5 Hz), 6.83
3
4
(dd, 1 H, H3, J HH ) 8.1, J FH ) 5.8 Hz), 7.29-7.55 (m, 15 H,
Ph). 31P{1H} NMR: δ 32.6 (s).
Syn t h esis of [P d {C6H 3(CH 2)2NH 2-2-NO2-5-κ2C,N}Cl-
(P P h 3)] (7). 4-Nitrophenethylamine-HCl (500 mg, 2.47 mmol)
and Pd(OAc)2 (554 mg, 2.47 mmol) were refluxed in acetonitrile
(40 mL) for 16 h. The resulting brown suspension was filtered
through a plug of MgSO4, the solvent removed, and CH2Cl2
1
solvent site near an inversion center was interpreted as /4 of
disordered CH2Cl2. The programs use neutral atom scattering
factors, ∆f ′ and ∆f ′′ values, and absorption coefficients from
ref 13.
1
added (20 mL). A brown solid was formed (353 mg) whose H
Ack n ow led gm en t. We thank the Ministerio de
Ciencia y Tecnolog´ıa and the FEDER (Grant No.
BQU2001-0133) for financial support.
NMR in acetone-d6 corresponded to a mixture of ortho-
metalated complex and [PdCl2(amine)2]. To a suspension of this
solid (100 mg) in CH2Cl2 (20 mL) was added PPh3 (90 mg, 0.34
mmol). After the mixture was stirred for 30 min, a brown
solution formed which was filtered through a plug of MgSO4
and concentrated to ca. 1 mL. A yellow solid (50 mg, 0.98 mmol,
30%) precipitated that proved to be [PdCl2(PPh3)] by 1H NMR
analysis. Et2O/n-hexane mixture (1:1,15 mL) was added to the
mother liquor and a dark yellow solid precipitated, which was
filtered, washed with n-hexane, and air-dried to afford complex
Su p p or tin g In for m a tion Ava ila ble: Listings of all re-
fined and calculated atomic coordinates, anisotropic thermal
parameters, and bond lengths and angles for 3a and 5, and
13C{1H} NMR data for complexes 3b and 5-7, and a figure
showing the N-H‚‚‚O hydrogen bonds for complex 5; crystal-
lographic data for 3a and 5 are also available as CIF files.
This material is available free of charge via the Internet at
http://pubs.acs.org.
7. Yield: 69 mg, 37%. Mp: 126 °C. Anal. Calcd for C26H24
-
ClN2O2PPd: C, 54.85; H, 4.25; N, 4.92. Found: C, 55.18; H,
4.21; N, 4.60. 1H NMR: δ 2.61 (m, 2 H, CH2), 3.22 (m, 2 H,
OM030480D
3
CH2), 3.50 (m, 2 H, NH2), 6.93 (d, 1 H, H3, J HH ) 8.1 Hz),
(13) International Tables for Crystallography; Kluwer Academic:
Dordrecht, The Netherlands, 1992; Vol. C, Tables 6.1.1.4 (pp 500-
502), 4.2.6.8 (pp 219-222), and 4.2.4.2 (pp 193-199).
7.24-7.62 (m, 17 H, Ph + H4 + H6). 31P{1H} NMR: δ 33.6
(s).