Reaction of di-μ-dichloro-bis(N,N-dimethylbenzylamine-C2,N)dipalladium(II) with diphosphines. Six-membered ring complexes bearing spiro rings

Article abstract of DOI:10.1016/S0020-1693(99)00491-0

Reactions of [Pd(C₆H₄CH₂NMe₂-C²,N)(μ-Cl)]₂ with diphosphines (diphos) such as dppf (a), dpmf (b), dppm (c), dppe (d) and dppp (e) gave [PdCl(C₆H₄CH₂NMe₂-C²,N)]₂(μ-diphos) (2). Complexes 2 (a, b, d and e) reacted with NaPF₆ to produce chelate complexes [Pd(C₆H₄CH₂NMe₂-C²,N)(diphos-P,P')][PF₆] (3), whereas 2c gave a six-membered ring complex [Pd₂(C₆H₄CH₂NMe₂-C²,N)₂(μ-Cl)(μ-dppm)][PF₆] (4c) bearing two exocyclic rings shared by each palladium atom. This complex was regenerated to 2c by treatment with [NEt₃(CH₂Ph)]Cl. Treatment of 3 (a, d and e) with one equiv. of aq. HCl caused protonation at the coordinate nitrogen atom to yield [Pd(C₆H₄CH₂NHMe₂-C²)(Cl)(diphos-P,P')][PF₆] (5) (a, d and e). Reaction of 4c with aq. HCl in a 1:1 molar ratio led to protonation at one C-N chelating ring to give [Pd₂(Cl)(C₆H₄CH₂NMe₂-C²,N)(C₆H₄CH₂NHMe₂-C²)(μ-Cl)(μ-dppm)][PF₆] (6c). The structures of 2a, 3e, 4c, 5a and 6c were confirmed by X-ray analyses. (C) 2000 Elsevier Science S.A.

Full text of DOI:10.1016/S0020-1693(99)00491-0

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Inorganica Chimica Acta 299 (2000) 164–171
Reaction of di-m-dichloro-bis(N,N-dimethylbenzylamine-
C2,N)dipalladium(II) with diphosphines. Six-membered ring
complexes bearing spiro rings
Jian-Fang Ma 1, Yasuhiro Yamamoto *
Department of Chemistry, Faculty of Science, Toho Uni6ersity, Miyama, Funabashi, Chiba 274-8510, Japan
Received 15 July 1999; accepted 12 October 1999
Abstract
Reactions of [Pd(C6H4CH2NMe2-C2,N)(m-Cl)]2 with diphosphines (diphos) such as dppf (a), dpmf (b), dppm (c), dppe (d) and
dppp (e) gave [PdCl(C6H4CH2NMe2-C2,N)]2(m-diphos) (2). Complexes 2 (a, b, d and e) reacted with NaPF6 to produce chelate
complexes [Pd(C6H4CH2NMe2-C2,N)(diphos-P,P%)][PF6] (3), whereas 2c gave a six-membered ring complex [Pd2(C6H4CH2NMe2-
C2,N)2(m-Cl)(m-dppm)][PF6] (4c) bearing two exocyclic rings shared by each palladium atom. This complex was regenerated to 2c
by treatment with [NEt3(CH2Ph)]Cl. Treatment of 3 (a, d and e) with one equiv. of aq. HCl caused protonation at the coordinate
nitrogen atom to yield [Pd(C6H4CH2NHMe2-C2)(Cl)(diphos-P,P%)][PF6] (5) (a, d and e). Reaction of 4c with aq. HCl in a 1:1
molar ratio led to protonation at one CꢀN chelating ring to give [Pd2(Cl)(C6H4CH2NMe2-C2,N)(C6H4CH2NHMe2-C2)(m-Cl)(m-
dppm)][PF6] (6c). The structures of 2a, 3e, 4c, 5a and 6c were confirmed by X-ray analyses. © 2000 Elsevier Science S.A. All rights
reserved.
Keywords: Crystal structures; Palladium complexes; Diphosphine complexes; ortho-Metalate complexes
1. Introduction
zolines [3], respectively. Cyclopalladated compounds of
azobenzenes, diarylazines, arylimines and their re-
lated derivatives can function as liquid crystals [4].
Di - m - chloro - bis(N,N - dimethylbenzylamine - C2,N)di -
palladium(II) (1), first reported by Cope and Friedrich
[5], reacted with N-donor ligands and phosphines to
give monomeric complexes by accompanying cleavage
of the Cl-bridges [6,7]. We have reported that complex
1 reacted with isocyanide to produce iminoacyl com-
It has been known for some time that diphosphine
ligands enhance the stability of various metal com-
plexes because of the chelating effect. A correlation
between the PꢀMꢀP bite angle in diphosphine com-
plexes and selectivity has been observed in various
catalytic reactions such as hydroformylation, hydrocya-
nation and cross coupling. Cyclometallated compounds
of transition metals have played an important role in
potential applications in organic synthesis, resolution of
enantiomers, photochemistry and bioinorganic chem-
istry [1]. Reactions of cyclopalladated complexes of
azobenzene with isocyanide or carbon monoxide gave
3-amino-2-phenylindazoline [2] and 3-oxo-phenylinza-
plexes which behaved as
a precursor to ortho-
aminomethylation or -iminomethylation to the
aromatic ring of N,N-dimethylbenzylamine [8].
During studies on the reactions between 1 and diphos-
phines bearing a different bite angle we found that
the reaction of 1 with bis(diphenylphosphino)methane
(dppm) produced a six-membered bimetallic complex
with two five-membered spiro rings. We now report the
formation and characterization of a six-membered metal-
lacyclic compound bearing two exo-cyclic rings and its
related complexes.
* Corresponding author. Tel.: +81-474-72 5076; fax: +81-474-75
1855.
E-mail address: yamamoto@chem.sci.toho-u.ac.jp (Y. Yamamoto)
1 On leave from Changchun Institute of Applied Chemistry, Chi-
nese Academy of Science.
0020-1693/00/$ - see front matter © 2000 Elsevier Science S.A. All rights reserved.
PII: S0020-1693(99)00491-0

J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
165
J
PH=2.3Hz, 12H, NMe2), 3.92 (s, 4H, NCH2), 6.3–7.8
2. Experimental
(m, Ph) ppm. 31P{1H} NMR (CD2Cl2): l 34.75 (s) ppm.
Anal. Calc. for C45H50N2Cl2P2Pd2·1/4CH2Cl2: C, 55.13;
H, 5.16; N, 2.84. Found: C, 55.16; H, 5.23; N, 2.75%.
All reactions were carried out under a nitrogen at-
mosphere. Complex 1 [5], 1,1%-bis[(diphenylphosphino)
methyl]ferrocene (dpmf) [9] (b) and 1,1%-bis[diphenyl-
phosphino]ferrocene (dppf) [10] (a) were prepared ac-
cording to the literature. Dichloromethane, n-hexane,
and benzene were distilled over CaH2 and diethyl ether,
over LiAlH4. Other reagents such as bis(diphenylphos-
phino)methane (dppm) (c), bis(diphenylphosphino)-
ethane (dppe) (d) and bis(diphenylphosphino)propane
(dppp) (e) were obtained commercially. The infrared
and electronic absorption spectra were measured on
FTIR-5300 and U-best 30 spectrometers, respectively.
NMR spectroscopy was carried out on a Bruker
2.2. Preparation of 3a
2.2.1. From the reaction of 2a with dppf in the
presence of NaPF6
To a solution of 2a·CH2Cl2 (53.2 mg, 0.03 mmol) and
dppf in a mixture of CH2Cl2 (5 ml) and acetone (5 ml)
was added NaPF6 (84 mg, 0.5 mmol) at room tempera-
ture. After stirring for 2 h, the solvent was removed
under reduced pressure. The residue was extracted with
CH2Cl2 (10 ml×2). When the volume was concen-
trated to approx. 3 ml, ether was added to give orange
1
AC250. H NMR spectra were measured at 250 MHz
crystals of 3a (10.2 mg, 66.4%). IR (Nujol): 838 cm−1
.
and 31P{1H} NMR spectra were measured using 85%
H3PO4 as an external reference.
1H NMR (CD2Cl2): l 2.12 (d, JPH=3.0 Hz, 6H, NMe),
4.17, 4.30, 4.48, 4.57 (s, 2H, C5H4), 4.21(d, JPH=2.4
Hz, NCH2), 6.3–7.9 (m, Ph) ppm. 31P{1H} NMR
2.1. Preparation of 2
(CD2Cl2): l 13.37 (d, JPP=32.5 Hz), 37.50 (d, JPP
=
32.5 Hz), −142.4 (s, JPF=710 Hz) ppm. Anal. Calc.
for C43H40NF6P3FePd.CH2Cl2: C, 51.56; H, 4.13; N,
1.37. Found: C, 51.86; H, 3.84; N, 1.06%.
2.1.1. Reaction of 1 with dppf (a)
To a solution of 1 (28 mg, 0.05 mmol) in CH2Cl2 (10
ml) was added dppf (28 mg, 0.05 mmol) at room
temperature. After stirring for 1 h, the solvent was
concentrated to approx. 3 ml under reduced pressure
2.2.2. From the reaction of 1 with dppf in the presence
of NaPF6
and diethyl ether was added to give yellow crystals of
To a solution of 1 (28 mg, 0.05 mmol) and dppf (56
mg, 0.1 mmol) in a mixture of CH2Cl2 (5 ml) and
acetone (5 ml) was added NaPF6 (84 mg, 0.5 mmol) at
room temperature. After stirring for 3 h, the solvent
was removed under reduced pressure. The residue was
extracted with CH2Cl2 (10 ml×2). The solvent was
concentrated to approx. 3 ml, ether was added to give
orange crystals of 3a (30 mg, 33%). Complex 3c (white,
42%). IR (Nujol): 839 cm−1. 1H NMR (CD3COCD3): l
3.02 (t, JPH=JP%H=2.4 Hz, 6H, NMe2), 4.30 (s, 2H,
NCH2), 4.56 (dd, JPH=12.5 Hz, JP%H=7.5Hz, 2H,
PCH2), 6.6–8.3 (m, Ph) ppm. 31P{1H} NMR
(CD3COCD3): l −25.55 (d, JPP=50.7 Hz), −0.95 (d,
1
2a (52 mg, 94%). H NMR (CD2Cl2): l 2.74 (d, JPH
=
2.6 Hz, 12H, NMe), 4.03 (s, 4H, NCH2), 4.46, 5.08 (s,
4H, C5H4), 6.2–7.6 (m, Ph) ppm. 31P{1H} NMR
(CD2Cl2):
l
33.90 (s) ppm. Anal. Calc. for
C52H52N2Cl2P2FePd2: C, 56.45; H, 4.74; N, 2.53.
Found: C, 56.49; H, 4.59; N, 2.44%.
Complexes 2b, 2c, 2d and 2e were prepared using
appropriate diphosphines by a method similar to that
1
for 2a. Complex 2b (yellow, 81%): H NMR (CD2Cl2):
l 2.77 (d, JPH=2.7 Hz, 12H, NMe), 3.68 (d, JPH=10.2
Hz, 2H, PCH2) 3.81 (s, 4H, C5H4) 3.88 (d, JPH=2.5
Hz, 2H, NCH2), 3.96 (s, 4H, C5H4), 6.3–7.8 (m, 8H,
Ph) ppm. 31P{1H} NMR (CD2Cl2): l 37.65 (s) ppm.
Anal. Calc. for C54H56N2Cl2P2FePd2: C, 57.17; H, 4.97;
J
PP=50.7 Hz), −143.0 (sep. JPF=710 Hz) ppm. Anal.
Calc. for C34H34NF6P3Pd·CH2Cl2: C, 49.19; H, 4.24; N,
N, 2.47. Found: C, 57.07; H, 4.83; N, 2.43%. Complex
1.64. Found: C, 49.83; H, 4.80; N, 1.66. Complex 3d
1
1
(white, 70%). IR (Nujol): 839 cm−1 (PF6). H NMR
2c (white, 64%): H NMR (CD2Cl2): l 2.61 (d, JPH
=
2.7 Hz, 12H, NMe3), 3.79 (s, 4H. NCH2), 4.84 (t,
(CD3COCD3): l 2.53 (m, 2H, PCHa), 2.66 (s, 6H,
NMe2), 4.34 (s, 2H NCH2), 6.5–8.2 (m, Ph) ppm.
31P{1H} NMR (CD3COCD3): l 39.00 (d, JPP=25.3
Hz), 59.72 (d, JPP=25.3 Hz), −146.1 (sep. JPF=706
Hz, PF6) ppm. Anal. Calc. for C35H36NF6P3Pd: C,
53.62; H, 4.61; N, 1.79. Found: C, 53.80; H, 4.50; N,
JPH=13.0 Hz, 2H, PCH2), 6.0–8.1 (m, Ph) ppm.
31P{1H} NMR (CD2Cl2): l 32.18 (s) ppm. Anal. Calc.
for C54H56N2Cl2P2FePd·1/4CH2Cl2: C, 54.69; H, 5.03;
N, 2.88. Found: C, 55.00; H, 4.85; N, 2.94. Complex 2d
(white, 84%): 1H NMR (CD2Cl2): l 2.74 (s, 12H,
NMe2), 2.77 (s, 4H. PCH2), 4.00 (s, 4H, NCH2), 6.3–
7.8 (m, Ph) ppm. 31P{1H} NMR (CD2Cl2): l 38.08 (s)
ppm. Anal. Calc. for C44H48N2Cl2P2Pd2·1/4CH2Cl2: C,
54.69; H, 5.03; N, 2.88. Found: C, 55.29; H, 4.96; N,
1
1.71. 3e (white, 52%). IR (Nujol): 839 cm−1 (PF6). H
NMR (CD3COCD3): l 2.41 (d, JPH=1.8 Hz, 6H,
NMe2), 2.4–2.7 (m, 6H, P(CH2)3P), 4.28 (s, 2H NCH2),
6.4–8.2 (m, Ph) ppm. 31P{1H} NMR (CD3COCD3): l
−1.62 (d, JPP=53.5 Hz), 27.85 (d, JPP=53.5 Hz),
−143.1 (sep. JPF=706 Hz, PF6) ppm. Anal. Calc. for
1
2.73%. Complex 2e (white, 79%): H NMR (CD2Cl2): l
2.02 (m, 2H, CCH2C), 2.58 (m, 4H, PCH2), 2.69 (d,

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J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
C36H38NF6P3Pd: C, 54.18; H, 4.80; N, 1.76. Found: C,
54.21; H, 4.62; N, 1.57%.
tals of 4c (40 mg, 77%). IR (Nujol): 839 (PF6) cm−1
.
1H NMR (CD3COCD3): l 2.48 (d, JPH=2.5 Hz, 12H,
NMe2), 4.10 (s, 4H, NCH2), 4.71 (t, JPH=11.0 Hz,
PCH2), 6.4–8.2 (m, 28H, Ph) ppm. 31P{1H} NMR
(CD3COCD3): l 27.78 (s), −143.1 (sep, JPF=706
Hz, PF6) ppm. Anal. Calc. for C43H46N2ClF6P3Pd: C,
49.38; H, 4.43 N, 2.68. Found: C, 49.40; H, 4.27; N,
2.71%.
2.3. Preparation of 5
2.3.1. Reaction of 3a with HCl
To a solution of 3a (47 mg, 0.05 mmol) in acetone
(10 ml) was added 1.0 M aqueous HCl (0.05 ml) at
room temperature. After stirring for 1 h, the volume
was concentrated to approx. 3 ml and diethyl ether was
added to give yellow crystals of 5a (37 ml, 76%). IR
2.5. Preparation of 6c
1
(Nujol): approx. 2730 (HCl salt), 844 cm−1 (PF6). H
2.5.1. Reaction of 4c with aqueous HCl
NMR (CD2Cl2): l 2.45 (bs, 3H, NMe2), 3.04 (bs, 3H,
NMe2), 3.46 (m, 1H, NCH2), 3.72, 3.79, 4.26, 4.33,
4.43, 4.88, 5.15 (s, 1H, C5H4), 4.22 (m, 1H, NCH2),
6.5–8.2 (m, Ph), 9.43 (br, 1H, NH) ppm. 31P{1H}
NMR (CDCl3): l 33.51 (d, JPP%=31 Hz), 14.33 (d,
To a solution of 4c (53 mg, 0.05 mmol) in
acetone (10 ml) was added dropwise 1.0 M aqueous
HCl (0.05 ml) at room temperature. After stirring
for 1 h, the volume was concentrated to 3 ml and
diethyl ether was added to give white crystals of 7
(41 mg, 76%). IR (Nujol): approx. 2700 (HCl salt), 839
JPP%=31 Hz), −143.1 (sep,
J
PF=706 Hz, PF6)
ppm. 1H NMR (CD2Cl2+D2O (50:1)):
a
broad
(PF6) cm−1. H NMR (CD2Cl2): l 2.48 (d, JHH=5.0
1
peak at l 9.43 ppm disappeared and the multiplets
at 3.46 and 4.22 ppm were converted to two sig-
nals, respectively. Complex 5d (white, 42%). IR
Hz, 3H, NMe2), 2.75 (d, JPH=2.5 Hz, 3H, NMe2), 2.98
(d, JHH=5.0 Hz, 3H, NMe2), 3.30 (d, JPH=2.5 Hz,
3H, NMe2), 3.25 (q, JHH=11 Hz, 2H, CH2N), 3.87
(dd, JHH=12.5 Hz, JPH=3.5 Hz, 1H, CH2N+), 3.97
1
(Nujol): approx. 2730 (HCl salt), 839 cm−1. H NMR
(CD3COCD3): l 2.68 (d, JHH=5.0 Hz, 3H, NMe2),
2.87 (d, JHH=5.0 Hz, 3H, NMe2), approx. 3.2
(m, 4H, PCH2), 3.65 (dd, JHH=12.3 Hz, JHH%=7.5 Hz,
1H, NCH2), 4.06 (dd, JHH=12.3Hz, 1H, NCH), 6.8–
8.3 (m, Ph), 9.35 (br, 1H, NH) ppm. 31P{1H}
NMR (CD3COCD3): l 34.74 (d, JPP%=25.3 Hz), 55.59
(dd, JHH=12.5 Hz, 1H, CH2N+), 4.23 (q, JHH=JPH
=
12.5 Hz, 1H, CH2P), 4.59 (d, JHH=12.5 Hz, 1 H,
PCH2), 6.0–8.2 (m, Ph), 9.73 (b, 1H, NH) ppm.
31P{1H} NMR (CD2Cl2): l 28.59 (d, JPP%=20.2 Hz),
22.41 (d, JPP%=20.2 Hz), −143.1 (sep, JPF=706 Hz,
PF6) ppm. Anal. Calc. for C43H47N2Cl2F6P3Pd2: C,
47.71; H, 4.29; N, 2.59. Found: C, 47.97; H, 4.29; N,
2.50%.
(d, JPP%=25.3 Hz), −143.1 (sep,
JPF=709 Hz,
PF6) ppm. Anal. Calc. for C43H41NClF6P3FePd: C,
52.89; H, 4.23; N, 1.43. Found: C, 52.18; H,
3.94; N, 1.46. Anal. Calc. for C35H37NClF6P3Pd: C,
51.24; H, 4.55; N, 1.71. Found: C, 51.35; H,
4.41; N, 1.75. 5e (white, 40%). IR (Nujol): 2760
2.6. Structure determination
The crystals suitable for X-ray analyses of
2a·2CH2Cl2 and 5a were obtained by diffusion of di-
ethyl ether into CH2Cl2 solutions of the com-
plexes. Those of 3e, 4c and 6c were prepared by
diffusion of diethyl ether into acetone solutions
of the complexes. Data collection was carried out
on a Rigaku AFC5S diffractometer by the 2q–ꢀ scan
method using graphite-monochromated Mo Ka
1
(HCl salt), 839 (PF6) cm−1. H NMR (CD3COCD3): l
2.85 (bs, 3H, NMe2), 3.13 (d, 3H, NMe2),
approx. 2.3–3.3 (m, 6H, P(CH2)3P), approx.
3.64 (m, 1H, NCH2), 4.55 (d, JHH=12.3Hz, 1H,
NCH2), 6.6–8.3 (m, Ph), 9.23 (br, 1H, NH) ppm.
31P{1H} NMR (CD3COCD3): l −3.25 (d, JPP%=51.4
Hz), 20.19 (d, JPP%=51.4 Hz), −142.9 (sep, JPF=709
Hz, PF6) ppm. Anal. Calc. for C33H39NClF6P3Pd: C,
51.82; H, 4.71; N, 1.68. Found: C, 52.10; H, 4.71; N,
1.59%.
,
radiation (u=0.71069 A). The absorption correction
was made with €-scan methods. The structures
of all complexes were solved by Patterson methods
(DIRDIF92), except that 6c was solved by the
2.4. Preparation of 4c
direct method (SIR92). Hydrogen atoms were calculated
,
at the ideal positions with the CꢀH distance of 0.95 A,
2.4.1. Reaction of 2c with NaPF6
and were not refined. The positions of the non-hydro-
gen atoms were refined with anisotropic thermal
parameters by using full-matrix least-squares methods.
Final difference Fourier syntheses showed peaks at
heights up to 0.88–1.59 e A−3. All calculations were
performed using the TEXSAN crytallographic software
package from the Molecular Structure Corporation
[11].
To a solution of 2c (47 mg, 0.05 mmol) in a mixture
of CH2Cl2 (5 ml) and acetone (5 ml) was added NaPF6
(84 g, 0.5 mmol) at room temperature. After the mix-
ture was stirred for 3 h, the solvent was evaporated to
dryness and the residue was extracted with CH2Cl2
(10 ml×2). When the volume was concentrated to
3 ml, diethyl ether was added to give pale-yellow crys-

J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
167
ꢀ
Scheme 1. Reactions of [Pd(m-Cl)(C6H4CH2NMe2-C2,N)]2 (1) with diphosphines; PF6 was omitted for clarity. (C N=C6H4CH2NMe2-C2,N).
3. Results and discussion
doublets in the wide range from l −25 to 60 ppm. The
structures with a chelated diphosphine were revealed by
an X-ray analysis of 3e (Fig. 2). These complexes (3a,
3d and 3e) were also prepared by the direct reactions of
1 with two equiv. of diphosphine in the presence of
NaPF6. Analogously the dppm complex 3c could be
obtained by the reaction in a 1:2 ratio as an unstable
3.1. Reactions
The reactions of 1 with diphosphines such as dppf
(a), dpmf (b), dppm (c), dppe (d) and dppp (e) cleaved
the Cl-bridges to give 2a–e formulated as [PdCl-
(C6H4CH2NMe2-C2,N)]2(m-diphos) (Scheme 1). In the
1H NMR spectra of 2a–c and 2e the NMe2 and NCH2
protons showed a doublet due to 31P coupling at l
approx. 2.7 and a singlet at l approx. 4.0 ppm, respec-
tively; in 2d the NMe2 resonance was a singlet. Two
singlets for the cyclopentadienyl (Cp) groups were ob-
served at l 4.46 and 5.08 ppm for 2a and at l 3.81 and
3.96 ppm for 2b, respectively; the signals at higher fields
were assigned to a-protons of the Cp rings and those at
lower field were assigned to b-protons. The 31P{1H}
NMR spectra of 2 appeared at l 32–38 ppm as a
singlet. The dimeric structures of 2 with the m-diphos-
phine ligand were confirmed by an X-ray analysis of 2a
(Fig. 1).
1
white compound. The H NMR spectrum of 3c showed
a triplet at l 3.02 ppm (JPH=JP%H=2.4 Hz) due to
NMe2 and a singlet at l 4.30 due to NCH2 protons.
The dppm protons appeared at l approx. 4.5 ppm
(JPH=11.8 Hz and JP%H=7.5 Hz) as a double doublet.
When complexes (2a, 2d and 2e) were treated
with NaPF6 in acetone–CH2Cl2, the corresponding
cationic complexes [Pd(C6H4CH2NMe2-C2,N)(diphos-
P,P%)][PF6] (3a, 3d [12] and 3e) were isolated as stable
1
white crystals. In the H NMR spectra of 3 a doublet
for the NMe2 protons and a singlet for NCH2 protons
appeared at l approx. 2.4 and 4.3 ppm, respectively.
The Cp ring protons of 3a showed two doublets at l
4.20 and 4.30 ppm having JPH=2.0 Hz, and two
singlets at l 4.48 and 4.57 ppm; the former was as-
signed to a-protons in the Cp rings and the latter, to
b-protons. The 31P{1H} NMR spectra of 3 showed two
Fig. 1. Molecular structure of [(C6H4CH2NMe2-C2,N)2Pd2Cl2(m-
dppf)] (2a) with thermal ellipsoids drawn at 50% probability level.
,
Selected bond lengths (A) and angles (°): Pd(1)ꢀCl(1), 2.397(2);
Pd(1)ꢀP(1), 2.251(2); Pd(1)ꢀN(1), 2.146(5); Pd(1)ꢀC(2), 2.010(7);
Cl(1)ꢀPd(1)ꢀP(1), 91.33(7); Cl(1)ꢀPd(1)ꢀN(1), 91.8(2); Cl(1)ꢀPd(1)ꢀ
C(2), 163.4(2); P(1)ꢀPd(1)ꢀN(1), 169.9(2); P(1)ꢀPd(1)ꢀC(2), 98.0(2);
N(1)ꢀPd(1)ꢀC(2), 81.4(3).

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J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
[Pd2(C6H4CH2NMe2-C2,N)2(dppm)(Cl)][PF6] contain-
ing two palladium atoms. The 1H NMR spectrum
showed a doublet at l 2.48 ppm due to the NMe2
protons, a singlet at l 4.10 ppm due to the NCH2
protons and a triplet at l 4.71 ppm due to PCH2P
protons. The resonance due to dppm was a singlet at l
27.78 ppm in the 31P{1H} NMR spectrum. These NMR
spectra suggested the structure with a highly symmetri-
cal entity consisting of two m-bondings by dppm and a
Cl atom. The X-ray analysis confirmed the proposed
structure (Fig. 3). Complex 4c was also obtained by the
direct reaction of 1 with one equiv. of dppm in the
presence of NaPF6.
When 4c was treated with [NEt3(CH2Ph)]Cl in a
mixture of acetone and CH2Cl2, cleavage of a Cl bridge
occurred readily to quantitatively regenerate 2c.
NaPF
6
2c _` 4c
[(PhCH )Et N]Cl
2
3
Complexes 3 (a, d and e) on treatment with aqueous
HCl in a 1:1 ratio at room temperature underwent
protonation at the coordinated nitrogen atom, and
white complexes [PdCl(C6H4CH2NHMe2-C2)(diphos-
P,P%)][PF6] (5a, d, and e) were obtained. Further addi-
tion of aq. HCl to 5d cleaved a PdꢀC bond to produce
PdCl2(dppe). The presence of the NH+ and PF6 moi-
eties was confirmed in the infrared spectra by bands at
approx. 2730 and 840 cm−1, respectively. The NH+
proton appeared at l approx. 9.4 ppm as a broad signal
which disappeared by treatment with D2O. Two signals
at l approx. 3.0 ppm for the NMe2 protons and at l
approx. 4.0 ppm for NCH2 protons were observed,
respectively, showing inequivalence of two methyl and
methylene protons which is probably due to restricted
rotation of the bulky N,N-dimethylbenzylammonium-
C2 group. These signals were converted to a singlet and
a quartet, respectively, by treatment with D2O. All Cp
ring-protons in 5a are also inequivalent, from appear-
ing at l 3.7–5.2 ppm as eight singlets. The inequiva-
lence of the ring protons was revealed by the ORTEP of
5a (Fig. 4). The 31P{1H} NMR spectrum showed two
doublets at l 14.38 and 33.50 ppm for dppf. An at-
tempt to convert 5a to 3a by treatment with NEt3 was
unsuccessful.
Fig. 2. Molecular structure of [(C6H4CH2NMe2-C2,N)Pd(dppp-
P,P%)][PF6] (3e) with thermal ellipsoids drawn at 50% probability
,
level. Selected bond lengths (A) and angles (°): Pd(1)ꢀP(1), 2.247(5);
Pd(1)ꢀP(2), 2.391(5); Pd(1)ꢀN(1), 2.18(1); Pd(1)ꢀC(2), 2.07(2);
P(1)ꢀPd(1)ꢀP(2), 89.2(2); P(1)ꢀPd(1)ꢀN(1), 168.4(5); P(1)ꢀPd(1)ꢀC(2),
91.8(6); P(2)ꢀPd(1)ꢀN(1), 100.7(4); P(2)ꢀPd(1)ꢀC(2), 169.8(5);
N(1)ꢀPd(1)ꢀC(2), 79.5(7).
Fig. 3. Molecular structure of [(C6H4CH2NMe2-C2,N)2Pd2(m-Cl)(m-
dppm)][PF6] (4c) with thermal ellipsoids drawn at 50% probability
When 4c was treated with one equiv. of aqueous
HCl, cleavage of one PdꢀN bond occurred to give white
crystals 6c formulated as [Pd2(C6H4CH2NMe2-
C2,N)(C6H4CH2NHMe2-C2)(dppm)(Cl2)][PF6]. It was
confirmed by X-ray analysis that the complex has a
six-membered ring structure with one spiro-ring (Fig.
5). The presence of an NH+ group was revealed by the
,
level. Selected bond lengths (A) and angles (°): Pd(1)ꢀCl(1), 2.4299(8);
Pd(1)ꢀP(1), 2.256(1); Pd(1)ꢀN(1), 2.159(3); Pd(1)ꢀC(2), 1.993(4);
Cl(1)ꢀPd(1)ꢀP(1), 92.49(4); Cl(1)ꢀPd(1)ꢀN(1), 92.27(10); Cl(1)ꢀPd(1)ꢀ
C(2), 170.4(1); P(1)ꢀPd(1)ꢀN(1), 170.54(8); P(1)ꢀPd(1)ꢀC(2), 94.6(1);
N(1)ꢀPd(1)ꢀC(2), 81.6(2); Pd(1)ꢀCl(1)ꢀPd(1%), 115.08(6); P(1)ꢀC(22)ꢀ
P(1%), 112.3(3).
1
infrared (2730 cm−1) and H NMR spectra (l 9.73 (bs)
The 31P{1H} NMR spectrum showed two doublets at l
−25.56 and −0.95 ppm, which shifted upfield in com-
parison with that (l 32.2 ppm) in 2c.
ppm). Four NMe2 groups were observed to be inequiv-
alent in the 1H NMR spectrum, again due to the
restricted rotation of an alkyl group. The 31P{1H}
NMR spectrum showed two doublets at l 28.6 and 22.4
ppm consisting of JPP=20 Hz; the former is assigned
Reaction of 2c with an equivalent of NaPF6 pro-
duced
a pale yellow complex 4c formulated as

J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
169
to the phosphorus nucleus coordinated to the Pd atom
containing a P,N-chelating ligand similar to that found
in 4c.
For metal complexes containing diphosphine ligands
with methylene, ethylene and trimethylene linkages, the
PꢀMꢀP bite angles formed by the chelating ligands are
approximately 75, 85 and 90°, respectively [13]. The
small bite angle of the dppm complexes (4c and 6c)
preferred a Cl-bridged structure to a chelating one,
because of release of steric strain of a four-membered
ring. Complexes bearing flexible dppf and dpmf ligands
formed more stable chelating structure.
3.2. Structure
3.2.1. Crystal structures of 2a, 3e and 5a
The selected bond lengths and angles of 2a·2CH2Cl2,
3e and 5a are shown in Figs. 1–3. Complex 2a has
crystallographic two-fold symmetry and sits astride a
two-fold axis making only one-half of the complex
unique (Fig. 1). Two planes containing a Pd atom are
connected with dppf. The P atom occupies the trans-
position to a N atom. The square plane of a molecule
cation in 3e is formed by the (P,P%) and (C,N) chelating
ligands (Fig. 2). A six-membered ring formed by the
chelating dppp ligand consists of a distorted boat-form,
different from the chair-form found in [NiCl-
(dppp)(XylNC)2][PF6] [13g]. The bite angle of 89.2(2)°
is in the range of those found in the diphosphine
complexes with a trimethylene linkage [13f]. The five-
membered rings containing a N coordination in 2a and
3e have an envelope conformation. The CꢀPdꢀN bite
angles of 2a and 3e are in the range 79–81°, similar to
those found in the related complexes.
Fig. 4. Molecular structure of [(C6H4CH2NHMe2-C2)Pd(Cl)(dppf-
P,P%)][PF6] (5a) with thermal ellipsoids drawn at 50% probability
,
level. Selected bond lengths (A) and angles (°): Pd(1)ꢀCl(1), 2.393(2);
Pd(1)ꢀP(1), 2.266(2); Pd(1)ꢀP(2), 2.401(2); Pd(1)ꢀC(36), 2.038(7);
Cl(1)ꢀPd(1)ꢀP(1), 171.48(7); Cl(1)ꢀPd(1)ꢀP(2), 82.24(7); Cl(1)ꢀPd(1)ꢀ
C(36), 89.1(2); P(1)ꢀPd(1)ꢀP(2), 99.46(7); P(1)ꢀPd(1)ꢀC(36), 85.4(2);
P(2)ꢀPd(1)ꢀC(36), 167.6(2).
A palladium atom of a cation in 5a is surrounded by
a chelating dppf, C and Cl atoms. The PꢀPdꢀP bite
angle of 99.46(7)° is not different from those found in
square planar Pd complexes [14].
The conformations of the ferrocenyl skeleton of 2a
and 5a are anticlinal (eclipsed) and anticlinal (stag-
gered), respectively. The anticlinal (eclipsed) conforma-
tion has been noted in a three-legged piano-stool
complex [(h5-MeCp)Mn(CO)2(dppf-P)] [15], in octahe-
dral complexes [Mn2(CO)9]2(mdppf) [16], cis-[Mo(CO)5-
(dppf-P)] [17], [Re2(CO)9]2(m-dppf) [16] and [h6-1,2.3.4-
Me4H2C6)2Ru2Cl4(dpmf)] [18]. A few complexes exist
having an anticlinal (staggered) conformation, [Ag2(m-
C6H5CO2)(m-dppf)] [19], and [(h6-1,2.3.4-Me4H2C6)2-
Ru2Cl4(dpmf)] [18].
Fig.
5.
Molecular
structure
of
[(C6H4CH2NMe2-C2,N)-
(C6H4CH2NHMe2-C2)Pd2Cl(m-Cl)(m-dppm)][PF6] (6c) with thermal
,
ellipsoids drawn at 50% probability level. Selected bond lengths (A)
and angles (°): Pd(1)ꢀC1(1), 2.453(2); Pd(1)ꢀCl(2), 2.386(2); Pd(1)ꢀ
P(1), 2.233(2); Pd(1)ꢀC(2), 2.005(9); Pd(2)ꢀCl(1), 2.429(3); Pd(2)ꢀP(2),
2.267(2); Pd(2)ꢀN(2), 2.134(8); Pd(2)ꢀC(36), 2.03(1); Cl(1)ꢀPd(1)ꢀ
Cl(2), 93.62(8); Cl(1)ꢀPd(1)ꢀP(1), 86.03(8); Cl(1)ꢀPd(1)ꢀC(2),
177.4(2); Cl(1)ꢀPd(1)ꢀP(2), 171.59(10); C1(2)ꢀPd(1)ꢀC(2), 88.8(2);
P(1)ꢀPd(1)ꢀC(2), 91.7(2); Cl(1)ꢀPd(2)ꢀP(2), 92.71(9); C1(1)ꢀPd(2)ꢀ
N(2), 90.7(3); Cl(1)ꢀPd(2)ꢀC(36), 169.0(3); P(2)ꢀPd(2)ꢀN(2), 171.2(3);
P(2)ꢀPd(2)ꢀC(36), 95.8(3); N(2)ꢀPd(2)ꢀC(36), 81.8(4); P(2)ꢀPd(2)ꢀ
N(2), 171.2(3); Pd(1)ꢀCl(1)ꢀPd(2), 100.59(9).
,
The average PdꢀP length of 2.40 A at the trans-posi-
tion to a C atom in 3e and 5a is longer than those at
,
,
the trans-position to a N (2.25 A) or Cl (2.27 A) atom,
attributable to the strong trans-influence of a C atom in
comparison with a Cl or N atom.

170
J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
3.2.2. Crystal structure of 4c and 6c
The selected bond lengths and angles of 4c and 6c are
shown in Figs. 4 and 5.
The molecular cation of 4c, similar to 2a, has crystal-
lographic two-fold symmetry and sits astride a two-fold
axis making one-half of the complex unique. The two
coordination squares are connected by m-dppm and a
bridging Cl atom with a dihedral angle of 71.8°. The
bridge Crystallographic Data Centre. CCDC numbers:
2a: 135366; 3e: 135367; 4c: 135368; 5a: 135369; 6c:
135370. Copies of this information may be obtained
free of charge from: The Director, CCDC, 12 Union
Road, Cambridge, CB2 1EZ, UK (fax: +44-1223-336-
033; email: deposit@ccdc.cam.ac.uk or www: http://
www.ccdc.cam.ac.uk).
molecular skeleton consists of a six-membered ring,
¸¹¹¹¹¹¹¹¹¹¹¹¹¹¹¹¹¹¹º
[Pd(1)ꢀCl(1)ꢀPd(1%)ꢀP(1%)ꢀC(22)ꢀP(1)], which has
Acknowledgements
a
chair-like geometry. This six-membered ring is accom-
panied by two five-membered spiro-rings each with a
shared Pd atom. Coordination about the Pd atoms is
almost planar and the P atoms are located in the
trans-position to each N atom.
One of the authors (J.-F. Ma) was supported by a
grant-in-aid (the 60th Anniversary Foundation) from
Toho University.
The molecular skeleton of a cation in 6c consists of a
six-membered ring bridged by dppm and a Cl atom,
which has the boat configuration. The coordination
sphere of Pd(2) is retained as in 4c, whereas Pd(1) is
coordinated by two Cl atoms, one P atom and one
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carbon atom forming
a
cis-configuration. The
PdꢀClꢀPd angle of 100.6° in 6c is narrower than that
(115°) in 4c. The difference of these angles can be
traced back to the PꢀCꢀP bond angles; the angle in 4c
is 112.3(3)° and that in 6c is 122.7(5)°.
The dihedral angle between two coordination planes
is 39.0° and narrower than that in 4c, resulting in
liberation of a N-coordination. The Pd(1)ꢀCl(1) bridg-
,
ing bond length of 2.453(2) A is slightly longer than
,
another Pd(2)ꢀCl(1) one of 2.429(3) A. The average
,
PdꢀCl bridging length of 2.441 A is similar to those in
4c and is in the range typically observed in other
,
chloro-bridged dimer systems (approx. 2.30–2.45 A)
,
[20], whereas it is longer by approx. 0.05 A than a
,
PdꢀCl non-bridging bond (Pd(1)ꢀCl(2)=2.386(2) A).
The elongation of PdꢀCl bridging bond lengths suggests
delocalization in the Pd(1)ꢀCl(1)ꢀPd(2) system, al-
though Pd(1)ꢀCl(1) is formally a coordination bond
and Pd(2)ꢀCl(1) is a s-bond. The Pd(2)ꢀP(2) bond
,
,
length of 2.267(2) A is longer than that (2.233(2) A) of
Pd(1)ꢀP(1) since the trans-influence of the N(2) atom is
stronger than a Cl(2) anion.
,
,
The Pd···Pd separation of 4.10 A as well as 3.76 A
for 4c showed no PdꢀPd bond. These contacts are
longer than those in the A-frame palladium complexes
with two dppm and one small molecule (e.g. SO2 [21]
and MeCN [22]) as bridging ligands.
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Y.-S. Wen, Polyhedron 10 (1991) 2437.
It is interesting to note that a hydrogen bond is
formed between Cl(2) and N(1) with Cl(2)ꢀN(1)=3.17
,
A and Cl(2)ꢀH(47)ꢀN(1)=164.1°.
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4. Supplementary material
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R.-J. Wang, Inorg. Chem. 31 (1992) 4510.
Atomic coordinates, thermal parameters, and bond
lengths and angles have been deposited at the Cam-

J.-F. Ma, Y. Yamamoto / Inorganica Chimica Acta 299 (2000) 164–171
171
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.
.