Reactions of palladium complex of N,N-dimethylbenzylamine with aromatic phosphines bearing the methoxy groups at the 2,6-positions

Article abstract of DOI:10.1016/S0022-328X(00)00586-6

Reactions of [(C₆H₄CH₂NMe₂-C ²,N)PdCl]₂ (1) with (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP), bis(2,6-dimethoxyphenyl)phenylphosphine (BDMPP), and tris(2,6-dimethoxyphenyl)phosphine (TDMPP) gave the corresponding complexes [(C₆H₄CH₂NMe₂-C ²,N)PdCl(L)] (2a: L = MDMPP; 2b: L = BDMMP; 2c: L = TDMPP). Reactions of 2 with NaPF₆ led to replacement of the Cl atom with the methoxy-O atom to form the corresponding complexes [(C₆H₄CH₂NMe₂-C ²,N)Pd(L)]-(PF₆) (3). On treatment of 3 with HCl (aq), protonation occurred at the N atom in 3 to give [(C₆H₄CH₂NHMe₂-C ²)PdCl(L)] (5). Based on X-ray structural analyses of 2c, 3a, 3b, 5a and 5c, complexes (2b, 2c, 3b, 3c, 5b and 5c) bearing BDMPP and TDMPP ligands have square-pyramidal structures with a P-O coordination in the axial position and complexes (2a, 3a and 5a) bearing MDMPP have square planar structures. When a complex bearing triphenylphosphine [(C₆H₄CH₂NMe₂-C ²,N)PdCl(PPh₃)] was treated with NaPF₆, [(C₆H₄CH₂NMe₂-C ²,N)Pd(PPh₃)(O₂H)](PF₆) (4) bearing a H₂O ligand was obtained. The reaction with HCl (aq) led to a cleavage of a Pd-C bond to give [PdCl₃(PPh₃)][PhCH₂NHMe₂] (6). X-ray analyses of 4 and 6 were also carried out. Reactions of 1 or 2a with mesityl isocyanide (MesNC) proceeded with replacement of a Cl atom with isocyanide and insertion of isocyanide to produce [(C₆H₄CH₂NMe₂-C ²,N)PdCl(MesNC)] (7) and [C₆H₄CH₂NMe₂-C ²)PdCl(MesNC)₂] (8).

Full text of DOI:10.1016/S0022-328X(00)00586-6

www.elsevier.nl/locate/jorganchem
Journal of Organometallic Chemistry 616 (2000) 149–156
Reactions of palladium complex of N,N-dimethylbenzylamine with
aromatic phosphines bearing the methoxy groups at the
2,6-positions
Jian-Fang Ma 1, Yasushi Kojima, Yasuhiro Yamamoto *
Department of Chemistry, Faculty of Science, Toho Uni6ersity, Miyama, Funabashi, Chiba 274-8510, Japan
Received 12 June 2000; received in revised form 18 August 2000; accepted 23 August 2000
Abstract
Reactions of [(C6H4CH2NMe2-C2,N)PdCl]2 (1) with (2,6-dimethoxyphenyl)diphenylphosphine (MDMPP), bis(2,6-
dimethoxyphenyl)phenylphosphine (BDMPP), and tris(2,6-dimethoxyphenyl)phosphine (TDMPP) gave the corresponding com-
plexes [(C6H4CH2NMe2-C2,N)PdCl(L)] (2a: L=MDMPP; 2b: L=BDMMP; 2c: L=TDMPP). Reactions of 2 with NaPF6 led
to replacement of the Cl atom with the methoxy-O atom to form the corresponding complexes [(C6H4CH2NMe2-C2,N)Pd(L)]-
(PF6) (3). On treatment of 3 with HCl (aq), protonation occurred at the N atom in 3 to give [(C6H4CH2NHMe2-C2)PdCl(L)] (5).
Based on X-ray structural analyses of 2c, 3a, 3b, 5a and 5c, complexes (2b, 2c, 3b, 3c, 5b and 5c) bearing BDMPP and TDMPP
ligands have square-pyramidal structures with a P–O coordination in the axial position and complexes (2a, 3a and 5a) bearing
MDMPP have square planar structures. When a complex bearing triphenylphosphine [(C6H4CH2NMe2-C2,N)PdCl(PPh3)] was
treated with NaPF6, [(C6H4CH2NMe2-C2,N)Pd(PPh3)(O2H)](PF6) (4) bearing a H2O ligand was obtained. The reaction with HCl
(aq) led to a cleavage of a Pd–C bond to give [PdCl3(PPh3)][PhCH2NHMe2] (6). X-ray analyses of 4 and 6 were also carried out.
Reactions of 1 or 2a with mesityl isocyanide (MesNC) proceeded with replacement of a Cl atom with isocyanide and insertion
of isocyanide to produce [(C6H4CH2NMe2-C2,N)PdCl(MesNC)] (7) and [C6H4CH2NMe2-C2)PdCl(MesNC)2] (8). © 2000 Elsevier
Science B.V. All rights reserved.
Keywords: Palladium complexes; N,N-dimethylbenzylamine; Aromatic phosphines
(P,OMe) chelation in a manner similar to phosphi-
noether [3]. We have reported that the reactions
of bis[dichloro(arene)ruthenium(II)] with (2,6-di-
methoxyphenyl)diphenylphosphine (MDMPP), bis-
(2,6-dimethoxyphenyl)phenylphosphine (BDMPP) or
TDMPP gave various complexes bearing h1-P, h2-
(P,OMe), h2-(P,O) or h3-(P,O,O%) coordination modes,
depending on the arene and phosphine [4]. Bis-
1. Introduction
Tertiary aromatic phosphines bearing the methoxy
groups at the 2,6-positions of the phenyl group such as
tris(2,6-dimethoxyphenyl)phosphine (TDMPP) and
tris(2,4,6-trimethoxyphenyl)phosphine (TTMPP), and
their related phosphines have provided the characteris-
tic reactions because of high basicity and steric bulki-
ness [1,2]. These phosphines are known to have a
variety of coordination modes; the bidentate or triden-
tate chelate rings containing metal–O bonds derived
from elimination of methyl groups, and the hemilabile
[dichloro(pentamethylcyclopentadienyl)
iridium(III)],
isoelectronic to [(arene)RuCl2]2 reacted with MDMPP,
BDMPP and TDMPP to afford complexes bearing the
similar coordination modes [5].
Palladium(II) complexes and some of nickel(II) com-
plexes typically exhibit square-planar geometries. It has
* 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. Present address: Department of Chemistry,
Northeast Normal University, Changchun 130024, PR China.
been reported that
[Pd(MeCN)4][BF4]2 reacted with TTMPP to give a
pseudo-octahedral complex [Pd(TTMPP–P,OMe,
O%Me)2][BF4]2 defined by two phosphorus atoms and
a
square-planar complex
0022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00586-6

150
J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
two ether-oxygen atoms in an equatorial arrangement,
and two ether oxygen atoms in axial sites [6]. Average
62%): 1H-NMR (CDCl3): l 2.71 (d, JPH=2.5 Hz,
NMe2, 6H), 3.36 (s, OMe, 12H), 3.91 (d, JPH=2.0 Hz,
CH2, 2H), 6.3–8.0 (m, Ph, 15H) ppm. 31P{1H}-NMR
(CDCl3): l −1.45 (s, BDMPP). Anal. Calc. for
C31H35NO4ClPPd: C, 56.55; H, 5.36; N, 2.13. Found:
C, 56.66; H, 5.25; N, 2.05%. 2c (yellow, 70%): 1H-NMR
(CDCl3): l 2.70 (d, JPH=2.5 Hz, NMe2, 6H), 3.46 (s,
OMe, 18H), 3.95 (b, CH2, 2H), 6.3–7.3 (m, Ph, 13H)
ppm. 31P{1H}-NMR (CDCl3): l −17.00 (bs, TDMPP).
Anal. Calc. for C33H39NO6ClPPd: C, 55.17; H, 5.47; N,
1.95. Found: C, 54.36; H, 5.36; N, 1.80%.
,
Pd–Oax length in axial sites is longer by 0.6 A than that
in equatorial sites. Pseudo-octahedral complex
[Ni(TTMPP–P,O,OMe)2] has been prepared by chemi-
cal oxidation of a square-planar complex [Ni(TTMPP–
P,O)2] [7]. These octahedral complexes contain only
TTMPP as ligands.
Recently we have reported that the reaction of
[Pd(C6H4CH2NMe2–C2,N)Cl]2(m-dppm) with NaPF6
gave
a
binuclear six-membered ring complex,
[Pd2Cl(C6H4CH2NMe2–C2,N)2(m - Cl)(m - dppm)](PF6)
bridged by a Cl atom and a dppm ligand, but diphos-
phines (L–L) complexes such as dppe, dppp, dppf and
2.2. Reaction of 2a with NaPF6
dpmf
formed
corresponding
chelate
ones,
To a solution of 2a (60 mg, 0.10 mmol) in CH2Cl2 (5
ml)/ acetone (5 ml) was added NaPF6 (84 mg, 0.5
mmol) at r.t. After stirring for 3 h, the solvent was
removed and the residue was extracted with CH2Cl2 (10
ml×2). When the volume was concentrated to ca. 3 ml,
[Pd(C6H4CH2NMe2–C2,N)(L–L)](PF6) [8].
We were interested whether octahedral complexes
were formed or not, as observed in the nickel and
palladium complexes of TTMPP when two coordinate
sites were occupied by a ligand except TTMPP. We
report here the reactions of aromatic phosphines bear-
ing the methoxy groups at the 2,6-positions with the
C2,N-cyclometallated palladium complex of N,N-
dimethylbenzylamine.
diethyl ether was added to give pale yellow crystals of
1
3a (50 mg, 71%). H-NMR (CDCl3): l 2.94 (d, JPH
2.5 Hz, NMe2, 6H), 3.84 (s, OMe, 6H), 3.95 (d, JPH
=
=
2.0 Hz, CH2, 2H), 6.3–7.9 (m, Ph, 17H).
31P{1H}-NMR (CDCl3): l 29.75 (s, MDMPP), −143.7
(sep,
JPF=712 Hz, PF6). Anal. Calc. for
C29H31NF6O2P2Pd: C, 49.20; H, 4.41; N, 1.98. Found:
C, 49.30; H, 4.17; N, 2.08%.
2. Experimental
Complexes 3b and 3c were prepared by a method
1
All reactions were carried out under nitrogen atmo-
sphere. Complex 1 [PdCl(C6H4CH2NMe2-C2,N)]2 [9],
aromatic phosphines [2] such as MDMPP (a), BDMPP
(b) and TDMPP (c), and [(C6H4CH2NMe2–
C2,N)PdCl(PPh3)] [10] were prepared according to the
literature. Dichloromethane, n-hexane and diethyl ether
were distilled from CaH2. The infrared (IR) and elec-
tronic absorption spectra were measured on FT/IR-
5300 and U-best 30 spectrometers, respectively. NMR
spectroscopy was carried out on a Bruker AC250.
1H-NMR spectra were measured at 250 MHz and
31P{1H}-NMR spectra were measured using 85%
H3PO4 as an external reference.
similar to that for 3a. 3b (pale yellow, 75%): H-NMR
(CDCl3): l 2.90 (d, JPH=2.5 Hz, NMe2, 6H), 3.61 (s,
OMe, 12H), 3.92 (b, CH2, 2H), 6.5–8.1 (m, Ph, 15H).
31P{1H}-NMR (CDCl3): l 14.98 (s, BDMPP), −143.7
(sep,
JPF=712 Hz, PF6). Anal. Calc. for
C31H35NF6O4P2Pd: C, 48.48; H, 4.59; N, 1.82. Found:
C, 48.67; H, 4.54; N, 1.88%. 3c (pale yellow, 80%):
1H-NMR (CDCl3): l 2.80 (d, JPH=2.5 Hz, NMe2,
18H), 3.46 (s, OMe, 3H), 3.87 (d, JPH=2.0 Hz, CH2,
2H), 6.3–7.4 (m, Ph, 13H). 31P{1H}-NMR (CDCl3): l
−19.74 (s, TDMPP), −143.8 (sep, JPF=712 Hz, PF6).
Anal. Calc. for C33H39NF6O6P2Pd: C, 47.87; H, 4.75;
N, 1.69. Found: C, 47.83; H, 4.56; N, 1.57%.
2.1. Reaction of 1 with MDMPP (a)
2.3. Reaction of [(C6H4CH2NMe2–C2,N)PdCl(PPh3)]
with NaPF6
MDMPP (33 mg, 0.1 mmol) was added to a solution
of 1 (28 mg, 0.05 mmol) in CH2Cl2 (10 ml) at room
temperature (r.t.). After stirring for 1 h, the solvent was
reduced to ca. 2 ml under reduced pressure and diethyl
ether was added to give yellow crystals of 2a (45 mg,
75%). 1H-NMR (CDCl3): l 2.76 (d, JPH=2.5 Hz,
NMe2, 6H), 3.45 (s, OMe, 6H), 4.00 (d, JPH=2.0 Hz,
CH2, 2H), 6.3–7.9 (m, Ph, 17H). 31P{1H}-NMR
(CDCl3): l 23.67 (s, MDMPP). Anal. Calc. for
C29H31NO2ClPPd: C, 58.21; H, 5.22; N, 2.34. Found:
C, 58.38; H, 5.18; N, 2.29%. Complexes 2b and 2c were
prepared by a method similar to that for 2a. 2b (yellow,
To a solution of [(C6H4CH2NMe2-C2,N)PdCl(PPh3)]
(54 mg, 0.10 mmol) in acetone (15 ml) was added
NaPF6 (35 g, 0.21 mmol) at r.t. and the mixture was
stirred for 1 h. The solvent was evaporated and the
residue was extracted with CH2Cl2. The solvent was
removed and the residue was crystallized from CH2Cl2
and diethyl ether to give colorless crystals of 4 (23.5
mg, 35%). IR(nujol): 3580, 3509 (H2O), 829 (PF6)
cm−1. 1H-NMR (CD3COCD3): l 2.79 (d, JPH=2.7 Hz,
NMe, 6H), 2.90 (s, NCH2, 2H), 4.31 (s, H2O, 2H),
6.3–7.9 (m, Ph, 19H). 31P{1H}-NMR (CDCl3): l 42.95

J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
151
(s, PPh3), −143.1 (sep, JPF=712 Hz, PF6). Anal. Calc.
for C27H29NOF6P2Pd: C, 48.70; H, 4.39; N, 2.10.
Found: C, 48.88; H, 4.30; N, 2.35%.
crystals of 7 (62 mg, 41.7%). IR(nujol): 2181 cm−1
(N°C). H-NMR(CDCl3): l 2.29 (s, p-Me, 1Me), 2.45
(s, o-Me, 2Me), 2.85 (s, NMe2, 2Me), 4.00 (s, NCH2,
2H), 6.6–7.7 (m, Ph, 6H). Anal. Calc. for
C19H23N2ClPd: C, 54.17; H, 5.50; N, 6.65. Found: C,
54.15; H, 5.56; N, 6.65%.
1
2.4. Reaction of 3a with Hcl(aq.)
To a solution of 3a (35 mg, 0.05 mmol) in acetone
was added 1.0 mM HCl (aq.) (0.05 ml) at r.t. After
stirring for 1 h, the volume was concentrated to ca. 3
ml and diethyl ether was added to give pale yellow
crystals of 5a (20 mg, 54%). IR(nujol): ca. 2700 (NH+),
2.6.2. Reaction of 2a with mesityl isocyanide
To a solution of 2a (98 mg, 0.16 mmol) in CH2Cl2
(20 ml) was added mesityl isocyanide (55 mg, 0.38
mmol) at r.t. and the mixture was stirred for 1 h. The
solution was concentrated to ca. 3 ml and diethyl ether
was added to give yellow crystals of 8 (50 mg, 74%).
839 (PF6) cm−1 1H-NMR (CD3COCD3): l 2.73 (d,
.
JPH=5.1 Hz, NMe, 3H), 3.10 (d, JPH=5.3 Hz, NMe,
3H), 3.5–4.1 (m, CH2 and OMe, 8H), 6.6–8.1 (m, Ph,
17H), 9.35 (br, NH, 1H). 31P{1H}-NMR (CD3COCD3):
l 24.32 (s, MDMPP), −143.1 (sep, JPF=710 Hz, PF6).
Anal. Calc. for C29H32NClF6O2P2Pd: C, 46.79; H, 4.33;
N, 1.88. Found: C, 46.95; H, 4.12; N, 1.93%. 5b (65%,
pale yellow). IR(nujol): ca. 2700 (NH+), 839 (PF6)
cm−1. 1H-NMR (CD3COCD3): l 2.74 (d, JPH=5.1 Hz,
NMe, 3H), 3.10 (d, JPH=5.2 Hz, NMe, 3H), 3.5–4.0
(m, CH2 and OMe, 14H), 6.8–7.7 (m, Ph, 15H), 9.50
(br, NH, 1H). 31P{1H}-NMR (CD3COCD3): l 11.26 (s,
BDMPP), −143.0 (sep, JPF=710 Hz, PF6). Anal.
Calc. for C31H36NCl F6O4P2Pd: C, 46.29; H, 4.51; N,
1.74. Found: C, 46.31; H, 4.26; N, 1.85%. 5c: IR(nujol):
IR(nujol): 2189 (NꢀC), 1638 (CꢁN) cm−1 1H-NMR
.
(CDCl3): l 2.06 (s, p- and o-Me, 3Me), 2.26 (s, p-Me,
1Me), 2.27 (s, m-Me, 2Me), 3.50 (s, NCH2, 2H), 6.59 (s,
m-H, 2H), 6.79 (s, m-H, 2H), 7.1–7.5 (m, Ph, 4H).
Anal. Calc. for C29H34N3ClPd: C,61.48; H, 6.05; N,
7.41. Found: C, 61.53; H, 6.01; N, 7.39%.
Analogously complex 8 was obtained in 84% yield
from the reaction of 2c with mesityl isocyanide in a 1:2
ratio.
2.7. Structure determination
Complexes (2c, 3a, 3b, 4, 5a, 5c, 6 and 8) were
recrystallized from CH2Cl2–hexane or CH2Cl2–di-
ethylether. Cell constants were determined from 15 to
20 reflections on Rigaku four-circle automated diffrac-
tometer AFC5S. Intensities were measured by the 2q–
ꢀ scan method using Mo–Ka radiation (u=0.71069
1
2700 (NH+), 839 (PF6) cm−1. H-NMR (CD3COCD3):
l 2.73 (d, JPH=5.0 Hz, NMe, 3H), 3.07 (d, JPH=5.3
Hz, NMe, 3H), 3.2–4.3 (m, CH2 and OMe, 20H),
6.6–7.5 (m, Ph, 13H), 9.55 (br, NH, 1H). 31P{1H}-
NMR (CD3COCD3): l 24.32 (s, TDMPP), −143.1
,
(sep,
J
PF=710 Hz, PF6). Anal. Calc. for
A). Intensities were corrected for Lorentz and polariza-
C33H40NClF6O6P2Pd: C, 45.85; H, 4.66; N, 1.62.
Found: C, 45.94; H, 4.46; N, 1.73%.
tion effects. The absorption correction was made with
the y scan methods. Structures of 4 and 6 were solved
by direct methods (SIR-92) and those of the other
complexes by Patterson methods. The crystal of 3b
contained acetone as a crystal solvent. Complex 6 con-
sists of crystallographically two independent molecules.
Hydrogen atoms were calculated at the ideal positions
2.5. Reaction of [(C6H4CH2NMe2–C2,N)PdCl(PPh3)]
with HCl(aq.)
To a solution of [(C6H4CH2NMe2–C,N)PdCl(PPh3)]
(54 mg, 0.10 mmol) in acetone (15 ml) was added
aqueous HCl(aq.) (0.3 mmol) and the mixture was
stirred at r.t. for 1 h. The solvent was evaporated and
the residue was recrystallized from CH2Cl2 to give
,
with the C–H distance of 0.95 A. All non-hydrogen
atoms were refined anisotropically by full-matrix least-
squares methods. Atomic scattering factors were taken
from the usual tabulation of Cromer and Waber [11].
Anomalous dispersion effects were included in Fcalc [12];
the values of Df % and Df ¦ were those of Creagh and
McAuley [13]. All calculations were performed using
colorless crystals of
6
(21 mg, 34%). 1H-NMR
(CD3COCD3): l 2.83 (s, JPH=2.5 Hz, NMe, 6H), 4.46
(s, CH2, 2H), 7.45–7.9 (m, Ph, 20H), ca. 10 (br, NH,
1H). Anal. Calc. for C27H28NCl3PPd: C, 53.05; H, 4.78;
N, 2.29. Found: C, 53.23; H, 4.99; N, 2.42%.
the TEXSAN crytallographic software package [14].
2.6. Preparation of 7
3. Results and discussion
2.6.1. Reaction of 1 with mesityl isocyanide
3.1. Reactions
To a solution of 1 (100 mg, 0.18 mol) in CH2Cl2 (20
ml) was added mesityl isocyanide (53 mg, 0.37 mmol) at
r.t. After stirring for 1 h, the solvent was concentrated
to ca. 3 ml and diethyl ether was added to give yellow
Complex
1 reacted readily with MDMPP (a),
BDMPP (b) or TDMPP (c) in a 1:2 ratio at room
temperature to form yellow crystals 2 formulated

152
J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
Scheme 1.
as PdCl(C6H4CH2NMe2–C2,N)(L) (L=MDMPP,
BDMPP, TDMPP) in moderate yields (Scheme 1). The
1H-NMR spectra showed a doublet (JPH=2.5 Hz) at l
Analogously, 3 was obtained by the reaction of 1 with
the corresponding phosphine in a 1:2 molar ratio in the
presence of NaPF6. A band of ca. 840 cm−1 confirmed
1
a PF6 anion. The H-NMR spectra appeared at l ca.
ca. 2.7 due to the NMe2 protons, and a doublet (JPH
=
3.0 as a doublet due to the NMe2 protons and at l ca.
3.9 as a doublet or broad resonance due to the NCH2
protons, respectively. The methoxy protons appeared at
l 3.5–3.9 ppm as one singlet, suggesting rapid ex-
change between free and coordinate methoxy groups. It
was confirmed by X-ray analyses that 3a has a square-
planar structure and 3b has a distorted square-pyrami-
dal one (Figs. 2 and 3). The Pd–O bond length in the
2.5 Hz) or a broad resonance at l ca. 3.9 due to the
NCH2 protons, respectively. X-ray analysis of 2c re-
vealed that the molecule has a distorted square-pyrami-
dal structure with an apical Pd(1)–O(4) bond length of
,
2.920(8) A (Fig. 1). The Pd atom is sourrounded by
(N,C) and (P,O) bidentate ligands and a Cl atom, in
which the P atom is in a trans position to the N atom.
The P(1)–Pd(1)–C(2) angle of 98.6(3)° is wider than
other angles in the equatorial plane, minimizing steric
interaction with the phenyl group of the chelate ligand.
The presence of the apical P–O bond with a rela-
tively long bond length was concluded by comparison
with S-donor macrocyclic complexes, as follows; (1) in
octahedral palladium complexes [PdLs6]2+ bearing S-
donor macrocyclic ligands (Ls), the Pd–Seq bond dis-
tances in the equatorial plane are in the range from 2.26
,
equatorial plane is 2.21–2.27 A. The Pd(1)–Oap(4)
,
bond length of 3b is 3.007(3) A. It is resonable that 3c
,
to 2.36 A and those (Pd–Sax) in axial sites fall in the
,
range 2.95–3.27 A [15] and the difference between the
,
Pd–Seq and Pd–Sax bond lengths is ca. 0.8 A, (2) the
average Pd–O coordination bond length in the P–O
,
chelate complexes is ca. 2.23 A (vide infra) and the
,
apical Pd(1)–O(4) bond length of 2.920(8) A in 2c is 0.6
,
A longer than the average Pd–O coordination bond
length. Based on X-ray analyses of 3a and 3b (vide
infra), 2b bearing the BDMPP ligand is considered to
have a distorted square-pyramidal structure as well as
2c, but 2a to have a square-planar structure.
When 2 was treated with one equivalent of NaPF6,
substitution of the Cl anion with a methoxy-O atom
occurred to form pale yellow complexes 3, formulated
as [Pd(C6H4CH2NMe2–C2,N)(L)](PF6) (L=MDMPP,
Fig.
1.
Molecular
structure
of
[(C6H4CH2NMe2–
C2,N)PdCl(TDMPP–P)] (2c) with thermal ellipsoids drawn at 50%
,
probability level. Selected bond lengths (A) and angles (°): Pd(1)–
Cl(1), 2.414(3); Pd(1)–P(1), 2.296(3); Pd(1)–N(1), 2.183(9); Pd(1)–
C(2), 2.01(1); Pd(1)–O(4), 2.920(8); Cl(1)–Pd(1)–P(1), 98.7(1);
Cl(1)–Pd(1)–N(1), 92.1(3); Cl(1)–Pd(1)–C(2), 171.2(4); P(1)–Pd(1)–
N(1), 171.9(3); P(1)–Pd(1)–C(2), 98.6(3);N(1)–Pd(1)–C(2), 80.5(4);
Pd(1)–C(2)–C(1), 110.9(8); C(2)–C(1)–C(7), 116(1); C(1)–C(7)–
N(1), 106.9(9); Pd(1)–N(1)–C(7), 100.9(7); O(4)–Pd(1)–N(1),
101.2(3); O(4)–Pd(1)–C(2), 108.2(4); Cl(1)–Pd(1)–O(4), 77.6(2).
BDMPP or TDMPP). Treatment of
3
with
[(PhCH2)Et3N]Cl regenerated 2.
NaPF
6
2 _`
3
[(PhCH )Et N]Cl
2
3

J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
153
by means of Et3N was unsuccessful. A band due to a
NH+ group appeared at ca. 2750 cm−1 in the IR
1
spectrum. In the H-NMR spectra a NH+ group was
also confirmed by appearance of a broad resonance at
l ca. 9.5 and disappearance on treatment with D2O.
Furthermore, two kinds of doublets due to the N-
methyl protons, arising from hindered rotation of steri-
cally bulky benzyldimethylammonium moiety, became
two singlets by disappearance of coupling with the
H(N) atom. A broad resonance at l ca. 4.0 due to the
methoxy protons showed slow exchange between free
and coordinate ether–O atoms. X-ray analyses revealed
that 5a and 5c have the square-planar and distorted
square-pyramidal structures, respectively (Figs. 5 and
6). The Cl atom is in a trans position to the P atom: the
reaction occurred regioselectively. The average Pd(1)–
,
Cl(1) bond length of 2.384(2) A in 5 is shorter than the
Pd(1)–Cl(1) distance of 2c, due to less trans-influence
of the Pd–P bond. The apical Pd(1)–O(6) bond length
Fig. 2. Molecular structure of [(C6H4CH2NMe2C2,N)Pd(MDMPP–
P,OMe)](PF6) (3a) with thermal ellipsoids drawn at 50% probability
,
,
of 2.979(4) A in 5c is longer by ca. 0.7 A than the
,
level. A PF6 moiety was omitted for clarity. Selected bond lengths (A)
and angles (°): Pd(1)–P(1), 2.230(1); Pd(1)–O(1),2.209(3); Pd(1)–
N(1), 2.155(4); Pd(1)–C(2), 1.980(5); P(1)–Pd(1)–O(1), 81.4(1); P(1)–
Pd(1)–N(1), 171.3(1); P(1)–Pd(1)–C(2), 95.9(2); O(1)–Pd(1)–N(1),
100.1(1); O(1)–Pd(1)–C(2), 174.9(2); N(1)–Pd(1)–C(2), 82.0(2);
Pd(1)–O(1)–C(11), 115.8(3); O(1)–C(11)–C(10), 117.8(4); P(1)–
C(10)–C(11), 117.3(4); Pd(1)–P(1)–C(10), 100.5(2); Pd(1)–N(1)–
C(7), 101.8(3); N(1)–C(7)–C(1), 109.5(5); Pd(1)–C(2)–C(1), 112.3(4).
,
Pd(1)–O(4) bond length of 2.211(4) A. Complex 5b is
considered to have a square-pyramidal structure similar
to that of 5c.
In order to examine whether similar protonation
occurs in complexes without containing the P–O
bearing much bulky phosphine was assumed to have a
square-pyramidal structure as well as 3b.
Triphenylphosphine complex [PdCl(C6H4CH2NMe2–
C2,N)(PPh3)] was treated with NaPF6 in acetone to give
pale yellow crystals formulated as [Pd(C6H4CH2NMe2–
C2,N)(PPh3)(OH2)](PF6) 4 (Scheme 2). The IR spec-
trum showed the characteristic bands at 3580, 3509 and
829 cm−1; the last one was assigned to a PF6 group
and the other bands were assigned to a H2O group.
Chemical shift value of H2O protons appeared at l 4.31
1
in the H-NMR spectrum. X-ray analysis revealed that
the H2O ligand is in a trans position to the C atom
(Fig. 4).
It is known that the complex bearing the H2O ligand,
[Pd (C6H4CH2NMe2–C2,N) {CH (COMe2) (PPh3)}-
(OH2)]+, has exclusively been obtained from the reac-
tion of [Pd(C6H4CH2NMe2–C2,N) (MeCN)2]+ with the
ylide compound, Ph3PꢁCH(CONMe2) in acetonitrile
and a coordinate H2O group was derived from water in
acetonitrile [16]. The coordination ability of H2O sug-
gested to be stronger than those of acetone or MeCN in
this type of complexes.
On treatment of 3 with 1.0 mM HCl(aq.), a protona-
tion at the coordinate nitrogen atom occurred readily
to produce pale yellow crystals of 5 in relatively high
yield, formulated as [PdCl(C6H4CH2NHMe2–C2)(L)]-
(PF6) (Scheme 1). An attempt to eliminate HCl from 5
Fig. 3. Molecular structure of [(C6H4CH2NMe2C2,N)Pd(BDMPP–
P,OMe)](PF6) (3b) with thermal ellipsoids drawn at 50% probability
,
level. A PF6 moiety was omitted for clarity. Selected bond lengths (A)
and angles (°): Pd(1)–P(1), 2.259(1); Pd(1)–O(1), 2.232(3); Pd(1)–
N(1), 2.147(3); Pd(1)–C(2), 1.993(4); Pd(1)–O(4), 3.007(3); P(1)–
Pd(1)–O(1), 80.72(8); P(1)–Pd(1)–N(1), 169.26(9); P(1)–Pd(1)–C(2),
98.8(1); O(1)–Pd(1)–N(1), 99.5(1); O(1)–Pd(1)–C(2), 172.1(1); N(1)–
Pd(1)–C(2), 82.5(2); Pd(1)–O(1)–C(11), 116.3(3);O(1)–C(11)–C(10),
117.6(4); P(1)–C(10)–C(11), 117.4(3); Pd(1)–P(1)–C(10), 101.4(2);
Pd(1)–N(1)–C(7), 106.1(3); N(1)–C(7)–C(1), 109.8(3); Pd(1)–C(2)–
C(1), 112.9(4); P(1)–Pd(1)–O(4), 63.75(7); O(4)–Pd(1)–C(2), 94.1(1);
O(4)–Pd(1)–N(1), 105.6(1); O(1)–Pd(1)–O(4), 92.8(1).

154
J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
Scheme 2.
(MesNC) produced 7 with a terminal isocyanide ligand.
Further addition of mesityl isocyanide to 7 underwent
insertion of isocyanide into the metal–C bonds to give
8 (Scheme 3). The IR spectrum of 8 showed the charac-
teristic bands at 2189 and 1638 cm−1 due to N–C
triple and C–N double bonds, respectively. The struc-
ture with terminal and inserted isocyanide groups was
confirmed by X-ray analysis. Similar complexes have
been noted in t-butyl or 4-tolyl isocyanide [17].
4. Crystal structures
4.1. Structures of 4, 6 and 8
Selected bond distances and angles of 4, 6 and 8 are
indicated in Figs. 6–8. In complex 4, water is in a trans
position to the C atom. The Pd(1)–P(1) bond length of
,
2.273(2) A in 4 falls between those of neutral and ionic
Fig. 4. Molecular structure of [(C6H4CH2NMe2–C2,N)Pd(PPh3)-
(H2O)](PF6) (4) with thermal ellipsoids drawn at 50% probability
,
level. A PF6 moiety was omitted for clarity. Selected bond lengths (A)
and angles (°): Pd(1)–P(1), 2.273(2); Pd(1)–O(1), 2.221(7); Pd(1)–
N(1), 2.150(7); Pd(1)–C(2), 1.979(8); P(1)–Pd(1)–O(1), 88.9(2); P(1)–
Pd(1)–N(1), 174.6(2); P(1)–Pd(1)–C(2), 95.5(2); O(1)–Pd(1)–N(1),
93.4(3); O(1)–Pd(1)–C(2), 168.3(3); N(1)–Pd(1)–C(2), 83.2(3);
Pd(1)–N(1)–C(7), 103.4(5); N(1)–C(7)–C(1), 108.9(7); Pd(1)–C(2)–
C(1), 111.2(6).
chelate ring, the reaction of [PdCl(C6H4CH2NMe2–
C2,N)(PPh3)] with HCl was carried out. A Pd–C bond
cleaved to give [C6H5CH2NHMe2][PdCl3(PPh3)] (6),
which was confirmed by X-ray analysis (Fig. 7). A
similar reaction with 2c also cleaved a Pd–C bond to
give [C6H5CH2NHMe2][PdCl3(TDMPP)]. Enhancement
of electron density at the nitrogen atom by the O-coor-
dination appears to promote protonation, and the P–O
chelation caused increase of the Pd–C bond strength.
Fig. 5. Molecular structure of [(C6H4CH2NHMe2–C2)PdCl-
(MDMPP–P,OMe)](PF6) (5a) with thermal ellipsoids drawn at 50%
probability level. A PF6 moiety was omitted for clarity. Selected bond
,
lengths (A) and angles (°): Pd(1)–Cl(1), 2.382(1); Pd(1)–P(1),
2.221(1); Pd(1)–O(1), 2.217(3); Pd(1)–C(2), 1.984(5); Cl(1)–Pd(1)–
P(1), 175.76(6); Cl(1)–Pd(1)–O(1), 95.34(9); Cl(1)–Pd(1)–C(2),
93.0(1); P(1)–Pd(1)–O(1), 83.00(9); P(1)–Pd(1)–C(2), 88.5(1); O(1)–
Pd(1)–C(2), 171.1(2); Pd(1)–O(1)–C(11),118.2(3); O(1)–C(11)–
C(10), 116.7(4); P(1)–C(10)–C(11), 119.8(4); Pd(1)–P(1)–C(10),
101.8(2).
3.2. Reactions of 1 and 2a with isocyanide
Reactions of 1 or 2a with mesityl isocyanide

J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
155
Fig. 7. Molecular structure of one molecule in [(C6H4CH2NHMe2)]-
[PdCl3(PPh3)] (6) with thermal ellipsoids drawn at 50% probability
,
level. A PF6 moiety was omitted for clarity. Selected bond lengths (A)
and angles (°): Pd(1)–Cl(1), 2.306(1); Pd(1)–Cl(2), 2.395(1); Pd(1)–
Cl(3), 2.295(1); Pd(1)–P(1), 2.242(1); Pd(2)–Cl(4), 2.296(1); Pd(2)–
Cl(5), 2.375(1); Pd(2)–Cl(6), 2.297(2); Pd(2)–P(2), 2.233(1);
N(1)–C(43), 1.525(8); N(1)–C(44), 1.490(8); N(1)–C(45), 1.480(8);
N(2)–C(52), 1.512(8); N(2)–C(53), 1.481(7); N(1)–C(54), 1.487(7);
Cl(1)–Pd(1)–Cl(2), 90.94(5); Cl(1)–Pd(1)–Cl(3), 178.76(5); Cl(1)–
Pd(1)–P(1), 85.45(5); Cl(2)–Pd(1)–Cl(3), 90.02(5); Cl(2)–Pd(1)–P(1),
175.38(1); Cl(3)–Pd(1)–P(1), 93.62(5); Cl(4)–Pd(2)–Cl(5), 89.27(5);
Cl(4)–Pd(2)–Cl(6), 175.30(6); Cl(4)–Pd(2)–P(2),93.47(5); Cl(5)–
Pd(2)–Cl(6), 91.27(5); Cl(5)–Pd(2)–P(2), 176.46(5); Cl(6)–Pd(2)–
P(2), 85.82(5); C(43)–N(1)–C(44), 112.8(5); C(43)–N(1)–C(45),
111.1(5); C(44)–N(1)–C(45), 110.5(5); C(52)–N(2)–C(53), 110.8(5);
C(52)–N(1)–C(54), 112.3(4); C(53)–N(1)–C(54), 110.5(5).
Fig. 6. Molecular structure of [(C6H4CH2NHMe2–C2)PdCl-
(TDMPP–P,OMe)](PF6) (5c) with thermal ellipsoids drawn at 50%
probability level. A PF6 moiety was omitted for clarity. Selected bond
,
lengths (A) and angles (°): Pd(1)–Cl(1), 2.385(2); Pd(1)–P(1),
2.246(1); Pd(1)–O(4), 2.211(4); Pd(1)–C(2), 1.978(6); Pd(1)–O(6),
2.979(4); Cl(1)–Pd(1)–P(1), 174.02(6); Cl(1)–Pd(1)–O(4), 93.7(1);
Cl(1)–Pd(1)–C(2), 90.0(2); P(1)–Pd(1)–O(4), 82.8(1); P(1)–Pd(1)–
C(2), 93.6(2); O(4)–Pd(1)–C(2), 176.3(2); Pd(1)–O(4)–C(23),
119.2(4); O(4)–C(23)–C(18), 117.2(5); P(1)–C(18)–C(23), 119.2(5);
Pd(1)–P(1)–C(18), 101.4(2); O(6)–Pd(1)–C(2), 102.9(2); O(6)–
Pd(1)–Cl(1), 121.5(2); O(6)–Pd(1)–P(1), 62.26(9); O(4)–Pd(1)–O(6),
74.8(1).
,
being nearly parallel. The C(1)–N(1) (1.16(1) A) and
,
C(11)–N(2) (1.26(1) A) bond lengths are in the range of
complexes. The Pd(1)–O(1) length is compared with
those of the ether-O coordination. Complex 6 was
isolated as a benzyldimethylammonium salt of a
[PdCl3(PPh3)] anion and consists of crystallographically
two independent molecules. The Pd(1)–Cl(2) and
Pd(2)–Cl(5) bond lengths, which occupied a trans posi-
tion to the phosphorus atom, are longer than the
Pd(1)–Cl(1), Pd(1)–Cl(3), Pd(2)–Cl(4) and Pd–Cl(6)
bond lengths, due to higher trans-influence of the P
atom than that of the Cl atom. The bond lengths and
angles of the benzyldimethylammonium ion fall in
usual values. The geometry around the Pd atom of 8
consists of terminal and inserted carbon atoms of isocy-
anide ligands, Cl and N atoms, constructing a six-mem-
bered ring. Dihedradal angles between two phenyl rings
of isocyanides and a phenyl one of amine are 7–13°,
the typical C–N triple and double bonds, respectively.
The Pd–C(1)–N(1) amd C(1)–N(1)–C(2) angles are
nearly linear. The C(11)–Pd–N(3) bond angle is
90.5(4)°. The corresponding C–Pd–N bond angles of
2c and 3 were calculated to be 80.5–85.2°. The ring
expansion from a five-membered ring to a six-mem-
bered one caused increase of a chelate angle of 5–10°.
5. Conclusion
In the complex [Pd(TTMPP–P,OMe,O’Me)2][BF4]2
bearing only TTMPP ligand, the weak apical Pd–O
contact has been observed [6]. Complexes bearing the
BDMPP and TDMPP ligands had the square-pyra-
midal structures containing the apical Pd–O bond,
Scheme 3.

156
J.-F. Ma et al. / Journal of Organometallic Chemistry 616 (2000) 149–156
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2c, 148234 for 3a, 148235 for 3b, 148236 for 4, 148237
for 5c, 148238 for 6, 148239 for 5a, 148240 for 8.
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Acknowledgements
One of the authors (J.-F.M.) was supported by a
grant-in-aid (the 60th Aniversary Foundation) from
Toho University.
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