Reactivity of cyclometallated palladium(II) compounds derived from N-(benzylidene)xylylendiamines

Article abstract of DOI:10.1016/S0277-5387(02)01150-6

The reaction of [1,3-{Pd[2,3,4-(MeO)₃C₆HC(H)=NCH₂] (μ-O₂CMe)}₂C₆H₄] (1), with triphenylphosphine in a 1:2 molar ratio gave the doubly cyclometallated complex [1,3-{Pd[2,3,4-(MeO)₃C₆HC(H)=NCH₂] (OAc)(PPh₃)}₂C₆H₄] (3), after cleavage of the two acetate-bridges. Treatment of the chloro-bridged complexes [1,3-{Pd[2,3,4-(MeO)₃C₆HC(H)=NCH₂] (μ-Cl)}₂C₆H₄]₂ (2) and [1,4-{Pd[2,3,4-(MeO)₃C₆HC(H)=N-CH₂] (μ-Cl)}₂C₆H₄]₂ (8) with the tertiary monophosphines PPh₃, P(p-MeOC₆H₄)₃ and P(p-NMe₂C₆H₄)Ph₂ gave the doubly cyclometallated complexes [1,3-{Pd[2,3,4-(MeO)₃C₆HC(H)=NCH₂] (Cl)(PR₃)}₂C₆H₄] (PR₃= PPh₃, 4; P(p-MeOC₆H₄)₃, 5; P(p-NMe₂C₆H₄)Ph₂, 6) and [1,4-{Pd[2,3,4-(MeO)₃C₆HC(H)=NCH₂] (Cl)(PR₃)}₂C₆H₄] PPh₃ = 9; P(p-MeOC₆H₄)₃, 10; P(p-NMe₂C₆H₄)Ph₂, 11). Reaction of complex 4 with PPh₃ did not yield the expected non-cyclometallated complex. Reaction of complexes 2 and 8 with the tertiary diphosphine cis-Ph₂PCH=CHPPh₂, in a 1:4 molar ratio and NaClO₄, yielded the doubly cyclometallated complexes [1,3-{Pd[2,3,4-(MeO)₃C₆HC(H)=NCH₂] (Ph₂PCH=CHPPh₂-P,P)}₂C₆ H₄][ClO₄]₂ (7) and [1,4-{Pd[2,3,4-(MeO)₃C₆HC(H)= NCH₂](Ph₂PCH=CHPPh₂-P,P)}₂ C₆H₄][ClO₄]₂ (12), respectively, with the diphosphine as a chelating bidentate ligand.

Full text of DOI:10.1016/S0277-5387(02)01150-6

Polyhedron 21 (2002) 2063Á2069
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www.elsevier.com/locate/poly
Reactivity of cyclometallated palladium(II) compounds derived from
N-(benzylidene)xylylendiamines
Margarita Lo´pez-Torres a,*, Pilar Juanatey a, Jesu´s J. Ferna´ndez a, Alberto Ferna´ndez a,
Antonio Sua´rez a, Digna Va´zquez-Garc´ıa a, Jose´ M. Vila b,*
a Departamento de Qu´ımica Fundamental, Universidad de La Coruna, E-15071 La Coruna, Spain
˜
˜
b Departamento de Qu´ımica Inorga´nica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
Received 7 May 2002; accepted 28 June 2002
Abstract
The reaction of [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
the doubly cyclometallated complex [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
acetate-bridges. Treatment of the chloro-bridged complexes [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
{Pd[2,3,4-(MeO)3C6HC(H)ÄNÃCH2](m-Cl)}2C6H4]2 (8) with the tertiary monophosphines PPh3, P(p-MeOC6H4)3 and P(p-
NMe2C6H4)Ph2 gave the doubly cyclometallated complexes [1,3-{Pd[2,3,4-(MeO)3C6HC(H)ÄNCH2](Cl)(PR3)}2C6H4] (PR3ꢀ
PPh3, 4; P(p-MeOC6H4)3, 5; P(p-NMe2C6H4)Ph2, 6) and [1,4-{Pd[2,3,4-(MeO)3C6HC(H)ÄNCH2](Cl)(PR3)}2C6H4] (PR3ꢀPPh3,
9; P(p-MeOC6H4)3, 10; P(p-NMe2C6H4)Ph2, 11). Reaction of complex 4 with PPh3 did not yield the expected non-cyclometallated
complex. Reaction of complexes 2 and 8 with the tertiary diphosphine cis-Ph2PCHÄCHPPh2, in a 1:4 molar ratio and NaClO4,
yielded the doubly cyclometallated complexes [1,3-{Pd[2,3,4-(MeO)3C6HC(H)ÄNCH2](Ph2PCHÄCHPPh2-P,P)}2C6H4][ClO4]2 (7)
CHPPh2-P,P)}2C6H4][ClO4]2 (12), respectively, with the diphosphine as a
/
NCH2](m-O2CMe)}2C6H4] (1), with triphenylphosphine in a 1:2 molar ratio gave
NCH2](OAc)(PPh3)}2C6H4] (3), after cleavage of the two
NCH2](m-Cl)}2C6H4]2 (2) and [1,4-
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and [1,4-{Pd[2,3,4-(MeO)3C6HC(H)Ä
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NCH2](Ph2PCHÄ
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chelating bidentate ligand. # 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Cyclometallated palladium(II) compounds; N-(Benzylidene)xylylendiamines; Chloro-bridged complexes
1. Introduction
have found that by using flexible ligands it is possible to
bring the two metal centers sufficiently close together to
achieve intramolecular coordination of the metal atoms
via a second or a third ligand, as in compound 1, where
two palladium atoms are bridged by the metallated
Schiff base and by two acetato ligands [30]. We have
also found that the reaction of 1, 2 and 8 with the
tertiary diphosphine Ph2P(CH2)3PPh2 gives complexes
in which the phosphine bridges the two palladium atoms
intramolecularly, showing the tendency of these com-
pounds to undergo intramolecular coordination [30].
We were then interested in looking further into the
chemistry of these starting materials when they were
reacted with other phosphine ligands, such as tertiary
mono- and diphosphines. We observed that in the
former case, the phosphine binds to the two metal
centers with loss of intramolecular coordination and
change in the acetate ligand from the bridging bidentate
mode to the terminal monodentate mode. When the
The synthesis and reactivity of cyclometallated com-
plexes are relevant aspects of present day organometallic
chemistry due to the interesting applications they
present in, for example, organic and organometallic
chemistry [1,2], in the preparation of biologically active
compounds [3,4] or new metal mesogenic species [5].
Generally, cyclometallation involves the formation of
one carbon to metal bond per ligand; however, in some
cases, using the appropriate organic moiety it is possible
to form two sMÃ
/
C bonds, to give doubly cyclometal-
lated species [6Á27].
/
In recent years we have been interested in the double
cyclometallation of Schiff base ligands [28,29] and we
* Corresponding authors. Fax: ꢁ
981-167-065 (M.L.-T.)
E-mail addresses:
qideport@usc.es (J.M. Vila).
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34-981-595-012 (J.M.V.); ꢁ
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34-
qiluaafl@udc.es
(M. Lo´pez-Torres),
reaction was carried out with cis-Ph2PCHÄ
/
CHPPh2 in a
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 1 1 5 0 - 6

2064
M. Lo´pez-Torres et al. / Polyhedron 21 (2002) 2063Á2069
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1:2 molar ratio, an untreatable mixture was obtained,
instead of the expected intramolecularly bonded com-
plex, whereas reaction in a 1:4 molar ratio gave
compounds with the diphosphine acting as a chelating
ligand.
151.5 [d, C6, J(CP)ꢀ
137.4, 137.1 (C3, C7); 133.7 (C1); 129.9, 129.2, 128.7
(C8, C9, C10); 118.2 [d, C5, J(CP)ꢀ12.0]; 59.9 (CH2);
61.7, 60.6, 55.3 (MeO), 23.3 (CH3COO). PÃphenyl: Co
135.4d, J(PC)ꢀ12.0; Ci 131.5d, J(PC)ꢀ52.5; Cp 130.6;
Cm 128.2d, J(PC)ꢀ10.6.
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3.5]; 154.2 [d, C4, J(CP)ꢀ5.7];
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Compounds 4, 5 and 6 were prepared similarly and
isolated as white (4) or yellow (5 and 6) solids.
2. Experimental
2.1. Safety note: caution
2.3. [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
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Perchlorate salts of metal complexes with organic
ligands are potentially explosive. Only small amounts of
these materials should be prepared and handled with
great caution.
The synthesis of complexes 1, 2 and 8 has been
reported previously by us [30]. Solvents were purified by
standard methods [31]. Chemicals were reagent grade.
The phosphines PPh3, P(p-MeOC6H4)3, P(p-
NCH2](Cl)(PPh3)}2C6H4] (4)
Yield: 80%. Anal. Found: C, 58.7; H, 4.5; N, 2.2.
C64H60Cl2N2O6P2Pd2 requires: C, 59.2; H, 4.7; N, 2.2%.
IR: n(CÄ
PPh3]ꢁ, 1000 [Mꢂ
597 [(LÃ
H) Pd]ꢁ. 1H NMR (200 MHz, CDCl3, d ppm,
J Hz): 8.21 [d, 2H, Hi, J(HiP)ꢀ8.3], 5.72 [d, 2H, H5,
J(H5P)ꢀ6.3], 5.20 [br, 4H, CH2], 3.77 (s, 6H, MeO),
3.66 (s, 6H, MeO), 2.81 [s, 6H, C(4)Ã
MeO]. 31P{1H}
/
N)ꢀ
/
1610m cmꢂ1. FAB-MS: m/z 1037 [Mꢂ
/
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PPh3ꢂ
/
Cl]ꢁ, 739 [Mꢂ
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2PPh3ꢂ
Cl]ꢁ,
/
/
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NMe2C6H4)Ph2 and cis-Ph2PCHÄ/CHPPh2 were pur-
/
chased from Aldrich-Chemie. Microanalyses were car-
ried out using a Carlo Erba Elemental Analyser, Model
1108. IR spectra were recorded as Nujol mulls or
/
NMR (80.96 MHz, CDCl3, d ppm, J Hz): 43.0s.
13C{1H} NMR (50.28 MHz, CDCl3, d ppm): 172.3 [d,
polyethylene discs on a PerkinÁ
/
Elmer 1330 and Matt-
CÄ
J(CP)ꢀ
133.7 [d, C1, J(CP)ꢀ
C10); 117.8 [d, C5, J(CP)ꢀ
55.2 (MeO). PÃphenyl: Co 135.4d, J(PC)ꢀ
131.2d, J(PC)ꢀ46.8; Cp 130.7d, J(PC)ꢀ3.7; Cm
128.1d, J(PC)ꢀ10.6.
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N, J(CP)ꢀ
6.4]; 138.2 [d, C3, J(CP)ꢀ
1.4]; 130.1, 129.1, 128.8 (C8, C9,
11.0]; 60.8 (CH2); 61.9, 60.6,
12.0; Ci
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4.3]; 154.4, 152.0, (C2, C6); 154.3 [d, C4,
son spectrophotometer. NMR spectra were obtained as
CDCl3 solution and referenced to SiMe4 (1H, 13C{1H})
or 85% H3PO4 (31P{1H}) and were recorded on a Bruker
AC-200F spectrometer. All chemical shifts were re-
ported downfield from standards. The FAB-MS were
recorded using a VG Quatro mass spectrometer with a
Cs ion gun; 3-nitrobenzyl alcohol was used as the
matrix. Conductivity measurements were made on a
CRISON GLP 32 conductimeter using 10ꢂ3 mol dmꢂ3
solutions in dry MeCN.
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1.4]; 137.5 (C7);
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2.4. [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
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NCH2](Cl){P(p-MeOC6H4)3}}2C6H4] (5)
2.2. Preparation of [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
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Yield: 70%. Anal. Found: C, 56.8; H, 5.0; N, 1.9.
C70H72Cl2N2O12P2Pd2 requires: C, 56.9; H, 4.9; N,
NCH2](OAc)(PPh3)}2C6H4] (3)
1.9%. IR: n(CÄ
[M]ꢁ, 1127 [Mꢂ
[Mꢂ2PR3ꢂ
Cl]ꢁ, 597 [(LÃ
MHz, CDCl3, d ppm, J Hz): 8.20 [d, 2H, Hi, J(HiP)ꢀ
8.3], 7.40 (m, 3H, H8, H9, H10), 5.79 [d, 2H, H5,
J(H5P)ꢀ6.3], 5.20 [br, 4H, CH2], 3.77 (s, 6H, MeO),
3.67 (s, 6H, MeO), 2.87 [s, 6H, C(4)ÃMeO]; P(p-
MeOC6H4)3: 7.63 [dd, 12H, Ho, J(HoHm)ꢀ8.8,
J(PHo)ꢀ11.2], 6.87 [dd, 12H, Hm, J(PHm)ꢀ1.5],
3.80 (s, 18H, MeOÃ
). 31P{1H} NMR (80.96 MHz,
CDCl3, d ppm): 39.4s. 13C{1H} NMR (50.28 MHz,
CDCl3, d ppm): 171.9 [d, CÄN, J(CP)ꢀ2.8]; 154.4,
151.9, (C2, C6); 154.1 [d, C4, J(CP)ꢀ6.4]; 138.2 [d, C3,
J(CP)ꢀ1.4]; 137.4 (C7); 133.7 [d, C1, J(CP)ꢀ1.4];
130.2, 129.0, 128.7 (C8, C9, C10); 117.8 [d, C5, J(CP)ꢀ
12.0]; 60.8 (CH2); 61.9, 60.6, 55.3 (MeO); 55.2 (P(MeOÃ
C6H4)3). PÃphenyl: Cp 161.3d, J(PC)ꢀ2.1; Co 136.8d,
J(PC)ꢀ13.5; Ci 122.7d, J(PC)ꢀ55.4; Cm 113.6d,
J(PC)ꢀ12.0.
/
N)ꢀ
PR3]ꢁ, 1091 [Mꢂ
H) Pd]ꢁ. 1H NMR (200
/
1600m cmꢂ1. FAB-MS: m/z 1478
To a suspension of 1 (50 mg, 0.061 mmol) in C3H6O
(approximately 15 cm3), triphenylphosphine (32 mg,
0.122 mmol) was added. The solution was stirred for 24
h at room temperature, after which a yellow precipitate
appeared, which was filtered off, washed with cold
C3H6O, dried in vacuo, and recrystallized from
CHCl3/n-C6H14. Yield: 75%. Anal. Found: C, 60.3; H,
4.7; N, 2.2. C68H66N2O10P2Pd2 requires: C, 60.7; H, 4.9;
/
/
PR3ꢂ
Cl]ꢁ, 739
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N, 2.1%. IR: nas(COO)ꢀ
N)ꢀ
1610m cmꢂ1. FAB-MS: m/z 1024 [Mꢂ
OAc]ꢁ, 765 [Mꢂ OAc]ꢁ, 597 [(LÃH) Pd]ꢁ.
2PPh3ꢂ
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 8.07 [d, 2H,
Hi, J(HiP)ꢀ8.3], 5.70 [d, 2H, H5, J(H5P)ꢀ5.9], 4.85
[br, 4H, CH2], 3.75 (s, 6H, MeO), 3.64 (s, 6H, MeO),
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1580s; ns(COO)ꢀ
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1380s; n(CÄ
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/
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PPh3ꢂ
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2.86 [s, 6H, C(4)Ã
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MeO], 1.26 (s, 6H, MeCO2). 31P{1H}
/
NMR (80.96 MHz, CDCl3, d ppm): 41.2s. 13C{1H}
NMR (50.28 MHz, CDCl3, d ppm, J Hz): 176.9
/
/
/
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(CH3COO), 171.2 [d, CÄ
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N, J(CP)ꢀ/2.8]; 152.1, (C2);
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M. Lo´pez-Torres et al. / Polyhedron 21 (2002) 2063Á
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2.5. [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
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Complexes 9, 10 and 11 were prepared following a
similar procedure to the 3 and isolated as white (9) or
yellow (10 and 11) solids.
NCH2](Cl)(P(p-NMe2C6H4)Ph2)}2C6H4] (6)
Yield: 70%. Anal. Found: C, 59.1; H, 5.5; N, 4.1.
C68H70Cl2N4O6P2Pd2 requires: C, 59.0; H, 5.1; N, 4.0%.
2.7. [1,4-{Pd[2,3,4-(MeO)3C6HC(H)Ä
/
IR: n(CÄ
1080 [Mꢂ
2PR3ꢂ
Cl]ꢁ, 597 [(LÃ
CDCl3, d ppm, J Hz): 8.20 [d, 2H, Hi, J(HiP)ꢀ
5.83 [d, 2H, H5, J(H5P)ꢀ6.3], 5.20 [br, 4H, CH2], 3.76
(s, 6H, MeO), 3.66 (s, 6H, MeO), 2.86 [s, 6H, C(4)Ã
MeO]; P(p-NMe2C6H4)Ph2: 6.66 [dd, 4H, Hm,
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N)ꢀ
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1605m cmꢂ1. FAB-MS: m/z 1384 [M]ꢁ,
NCH2](Cl)(PPh3)}2C6H4] (9)
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PR3]ꢁ, 1044 [Mꢂ
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PR3ꢂ
/
Cl]ꢁ, 739 [Mꢂ
H) Pd]ꢁ. H NMR (200 MHz,
8.3],
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1
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/
Yield: 80%. Anal. Found: C, 58.9; H, 4.8; N, 2.2.
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C64H60Cl2N2O6P2Pd2 requires: C, 59.2; H, 4.7; N, 2.2%.
/
IR: n(CÄ
PPh3]ꢁ, 1000 [Mꢂ
1H NMR (200 MHz, CDCl3, d ppm, J Hz): 8.24 [d, 2H,
Hi, J(HiP)ꢀ8.3], 7.48 (s, 4H, H8), 5.72 [d, 2H, H5,
J(H5P)ꢀ6.3], 5.18 [br, 4H, CH2], 3.83 (s, 6H, MeO),
3.67 (s, 6H, MeO), 2.81 [s, 6H, C(4)Ã
MeO]. 31P{1H}
NMR (80.96 MHz, CDCl3, d ppm): 42.9s. 13C{1H}
NMR (50.28 MHz, CDCl3, d ppm): 172.2 (CÄN); 154.2,
151.9, (C2, C6); 154.3 [d, C4, J(CP)ꢀ6.4]; 137.4, 137.1
(C3, C7); 133.6 [d, C1, J(CP)ꢀ1.4]; 129.7 (C8); 117.9
[d, C5, J(CP)ꢀ12.0]; 60.5 (CH2); 61.8, 60.6, 55.2
(MeO). PÃphenyl: Co 135.4d, J(PC)ꢀ12.0; Ci 131.1d,
J(PC)ꢀ49.7; Cp 130.8d, J(PC)ꢀ2.1; Cm 128.0d,
J(PC)ꢀ10.6.
/
N)ꢀ
/
1610s cmꢂ1. FAB-MS: m/z 1037 [Mꢂ
/
/
/
PPh3ꢂ
/
Cl]ꢁ, 739 [Mꢂ
/
2PPh3ꢂ
Cl]ꢁ.
/
J(HoHm)ꢀ
/
8.8, J(PHm)ꢀ
/
1.5], 2.99 (s, 6H, NMe2).
31P{1H} NMR (80.96 MHz, CDCl3, d ppm): 41.2s.
13C{1H} NMR (50.28 MHz, CDCl3, d ppm): 171.9 [d,
/
/
/
CÄ
J(CP)ꢀ
133.7 [d, C1, J(CP)ꢀ
C10); 118.0 [d, C5, J(CP)ꢀ
55.3 (MeO); 39.9 (P(NMe2Ã
130.2, 151.8d, J(PC)ꢀ2.1, 1.4; Co 137.6d, 134.9d,
J(PC)ꢀ13.4, 12.4; Ci 132.9d, 113.4d, J(PC)ꢀ51.1;
Cm 127.8d, 111.2d, J(PC)ꢀ12.0, 10.6.
/
N, J(CP)ꢀ
6.4]; 138.3 [d, C3, J(CP)ꢀ
1.4]; 130.1, 129.0, 128.8 (C8, C9,
12.0]; 60.7 (CH2); 61.9, 60.6,
C6H4)). PÃphenyl: Cp
/
3.7]; 154.4, 151.8, (C2, C6); 154.1 [d, C4,
/
/1.4]; 137.3 (C7);
/
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2.6. Preparation of [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
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2.8. [1,4-{Pd[2,3,4-(MeO)3C6HC(H)Ä
/
NCH2](Ph2PCHÄCHPPh2-P,P)}2C6H4][ClO4]2 (7)
/
NCH2](Cl){P(p-MeOC6H4)3}}2C6H4] (10)
cis-Ph2PCHÄ
/
CHPPh2 (25.3 mg, 0.064 mmol) was
Yield: 60%. Anal. Found: C, 55.5; H, 4.9; N, 1.9.
C70H72Cl2N2O12P2Pd2 requires: C, 56.9; H, 4.9; N,
added to a suspension of 3 (25 mg, 0.016 mmol) in
C3H6O (15 cm3). The mixture was stirred for 2 h, after
which an excess of sodium perchlorate was added, and
the resulting solution stirred for a further 2 h. The
complex was then precipitated out by addition of water,
filtered off and dried in vacuo. Recrystallization from
CHCl3/C6H14 gave the final compound as a yellow solid.
Yield: 85%. Anal. Found: C, 56.8; H, 4.7; N, 1.6.
C80H74Cl2N2O14P4Pd2 requires: C, 56.7; H, 4.4; N,
1.9%. IR: n(CÄ
1478 [M]ꢁ, 1091 [Mꢂ
Cl]ꢁ. 1H NMR (200 MHz, CDCl3, d ppm, J Hz):
8.23 [d, 2H, Hi, J(HiP)ꢀ8.3], 7.47 (s, 4H, H8), 5.89 [d,
2H, H5, J(H5P)ꢀ6.3], 5.17 [br, 4H, CH2], 3.81 (s, 6H,
MeO), 3.68 (s, 6H, MeO), 2.88 [s, 6H, C(4)ÃMeO]; P(p-
MeOC6H4)3: 7.63 [dd, 12H, Ho, J(HoHm)ꢀ8.8,
J(PHo)ꢀ11.2], 6.87 [dd, 12H, Hm, J(PHm)ꢀ1.5],
3.83 (s, 18H, MeOÃ
). 31P{1H} NMR (80.96 MHz,
CDCl3, d ppm): 39.4s. 13C{1H} NMR (50.28 MHz,
CDCl3, d ppm): 172.0 [d, CÄN, J(CP)ꢀ3.6]; 154.3,
151.8, (C2, C6); 154.2 [d, C4, J(CP)ꢀ6.4]; 137.3, 137.1
(C3, C7); 133.6 (C1); 129.7 (C8); 117.8 [d, C5, J(CP)ꢀ
11.4]; 60.9 (CH2); 61.9, 60.6, 55.2 (MeO); 55.2 (P(MeOÃ
C6H4)3). PÃphenyl: Cp 161.3d, J(PC)ꢀ2.8; Co 136.9d,
J(PC)ꢀ13.5; Ci 123.3d, J(PC)ꢀ55.4; Cm 113.5d,
J(PC)ꢀ12.0.
/
N)ꢀ
/
1610sh, m cmꢂ1. FAB-MS: m/z
/
PR3ꢂ
/
Cl]ꢁ, 739 [Mꢂ
/
2PPh3ꢂ
/
/
/
/
/
/
/
1.6%. IR: n(CÄ
[M]ꢁ, 1099 [Mꢂ
(cis-Ph2PCHÄCHPPh2)ꢂ
molꢂ1 (in MeCN). 1H NMR (200 MHz, CDCl3, d
ppm, J Hz): 8.29 [d, 2H, Hi, J(HiP)ꢀ8.3], 6.94 [t, 1H,
H10, J(H9H10)ꢀ7.8], 6.68 (d, 1H, H9), 6.22 (s, 1H,
H8), 6.20 [dd, 2H, H5, J(H5P)ꢀ8.8, 5.8], 4.52 [br, 4H,
CH2], 3.94 (s, 6H, MeO), 3.72 (s, 6H, MeO), 3.16 [s, 6H,
C(4)Ã
MeO]. 31P{1H} NMR (80.96 MHz, CDCl3, d
ppm): 63.2 [d, J(PP)ꢀ
11.0], 51.5 d. 13C{1H} NMR
(50.28 MHz, CDCl3, d ppm): 179.5m (CÄN); 163.1 [d,
C6, J(CP)ꢀ121.4], 153.9 [d, C2, J(CP)ꢀ9.2]; 156.8
[dd, C4, J(CP)ꢀ12.1, 5.7]; 139.2, 136.9 (C3, C7); 130.9,
129.0, 129.2 (C8, C9, C10); 117.4 [dd, C5, J(CP)ꢀ11.0,
3.2]; 64.3 (CH2); 62.3, 60.0, 55.8 (MeO). PCHÄCHP:
145.2 [dd, J(PC)ꢀ49.7, 34.8], 143.8 [dd, J(PC)ꢀ41.2,
22.7]. PÃphenyl: Cp 130.4; Co 133.9d, 133.0, J(PC)ꢀ
12.8, 12.0; Ci 126.6d, 126.1d, J(PC)ꢀ54.6, 41.9; Cm
130.0d, J(PC)ꢀ11.4.
/
N)ꢀ
(cis-Ph2PCHÄ
Pd]ꢁ. LMꢀ
/
1605m cmꢂ1. FAB-MS: m/z 1495
CHPPh2)]ꢁ, 993 [Mꢂ
240 Vꢂ1 cm2
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
2.9. [1,4-{Pd[2,3,4-(MeO)3C6HC(H)Ä
/
/
/
NCH2](Cl){P(p-NMe2C6H4)Ph2}}2C6H4] (11)
/
/
Yield: 60%. Anal. Found: C, 58.7; H, 5.5; N, 4.1.
/
C68H70Cl2N4O6P2Pd2 requires: C, 59.0; H, 5.1; N, 4.0%.
/
/
IR: n(CÄ
[Mꢂ
PR3]ꢁ, 1044 [Mꢂ
Cl]ꢁ. 1H NMR (200 MHz, CDCl3, d ppm, J Hz):
8.22 [d, 2H, Hi, J(HiP)ꢀ8.3], 7.47 (s, 4H, H8), 5.83 [d,
/
N)ꢀ
1605sh, m cmꢂ1. FAB-MS: m/z 1080
/
/
/
/
/
PR3ꢂ
/
Cl]ꢁ, 739 [Mꢂ
/
2PR3ꢂ
/
/
/
/

2066
M. Lo´pez-Torres et al. / Polyhedron 21 (2002) 2063Á2069
/
2H, H5, J(H5P)ꢀ
MeO), 3.68 (s, 6H, MeO), 2.86 [s, 6H, C(4)Ã
NMe2C6H4)Ph2: 6.66 [dd, 4H, Hm, J(HoHm)ꢀ
J(PHm)ꢀ
1.5], 3.00 (s, 6H, NMe2ꢂ ): 31P{1H} NMR
(80.96 MHz, CDCl3, d ppm): 41.1s. 13C{1H} NMR
(50.28 MHz, CDCl3, d ppm): 171.9 [d, CÄN, J(CP)ꢀ
4.3]; 154.4, 151.7, (C2, C6); 154.2 [d, C4, J(CP)ꢀ5.7];
137.3, 137.1 (C3, C7); 133.6 [d, C1, J(CP)ꢀ1.4]; 129.8
(C8); 118.0 [d, C5, J(CP)ꢀ12.0]; 60.5 (CH2); 61.8, 60.6,
55.3 (MeO); 39.9 (P(NMe2ÃC6H4)). PÃphenyl: Cp
130.2, 151.8; Co 137.5d, 134.9d, J(PC)ꢀ14.2, 11.5; Ci
133.9d, 113.4d, J(PC)ꢀ57.5, 50.4; Cm 127.8d, 111.2d,
J(PC)ꢀ12.0, 10.6.
/
6.3], 5.18 [br, 4H, CH2], 3.82 (s, 6H,
MeO]; P(p-
8.8,
lower wavenumbers (as compared to the free ligand) due
to N-coordination of the imine [32,33]. The IR spectrum
also showed strong bands assigned to the symmetric and
asymmetric n(COO) vibrations, in agreement with those
/
/
/
expected for monodentate acetate ligands [34] (see
1
N and H5 resonances in the H
/
/
Section 2). The HCÄ
/
/
NMR spectrum were coupled to the phosphorus nucleus
8.3 and 5.9 Hz,
/
[d 8.07 and 5.70, respectively; J(HP)ꢀ
/
/
also, respectively], and in the 31P{1H} NMR spectrum,
the phosphorus resonance appeared as a singlet at d
41.2 in accordance with the symmetric nature of the
complex. These data are indicative of a phosphorus
/
/
/
/
/
trans to nitrogen geometry [35Á38]. The relative posi-
/
Compound 12 was synthesized following a similar
method to the 7 as a yellow solid.
tion of the phosphine ligand in the coordination sphere
of the palladium atom was confirmed by the highfield
shift of the signal corresponding to the C(4)Ã
group, due to shielding by a phenyl ring from the
phosphine [35Á38]. In complex 1, the signals assigned to
/
OMe
2.10. [1,4-{Pd[2,3,4-(MeO)3C6H1C(H)Ä
NCH2](Ph2PCHÄCHPPh2-P,P)}2C6H4]Ã
(12)
/
/
/
[ClO4]2
/
the diastereotopic CH2 protons in the 1H NMR
spectrum appeared as two doublets, due to the hindered
rotation of this group. However, only one rather broad
resonance at d 4.85 was assigned to the methylene group
in complex 3, after cleavage of the intramolecular-
bridges. The 13C{1H} NMR spectrum of 3 showed the
high-frequency shift of the resonances corresponding to
Yield: 95%. Anal. Found: C, 56.9; H, 4.8; N, 1.6.
C80H74Cl2N2O14P4Pd2 requires: C, 56.7; H, 4.4; N,
1.6%. IR: n(CÄ
[M]ꢁ, 993 [Mꢂ
290 Vꢂ1 cm2 molꢂ1 (in MeCN). H NMR (200 MHz,
CDCl3, d ppm, J Hz): 8.32 [d, 2H, Hi, J(HiP)ꢀ8.3],
6.67 (s, 4H, H8), 6.19 [dd, 2H, H5, J(H5P)ꢀ9.3, 5.9],
4.62 [br, 4H, CH2], 3.91 (s, 6H, MeO), 3.72 (s, 6H,
MeO), 3.15 [s, 6H, C(4)Ã
MeO]. 31P{1H} NMR (80.96
MHz, CDCl3, d ppm): 63.1 [d, J(PP)ꢀ11.0], 51.5d.
13C{1H} NMR (50.28 MHz, CDCl3, d ppm): 179.1m
(CÄN); 162.9 [d, C6, J(CP)ꢀ122.0], 153.8 [d, C2,
J(CP)ꢀ9.2]; 156.7 [dd, C4, J(CP)ꢀ12.1, 5.7]; 139.1,
135.6 (C3, C7); 128.1 (C8); 117.4 [dd, C5, J(CP)ꢀ11.0,
3.2]; 64.2 (CH2); 62.2, 60.9, 55.8 (MeO). PCHÄCHP:
145.3 [dd, J(PC)ꢀ49.6, 34.8], 143.7 [dd, J(PC)ꢀ40.4,
22.7]. PÃphenyl: Cp 132.5; Co 134.0d, 133.1, J(PC)ꢀ
12.8; Ci 126.7d, 126.1d, J(PC)ꢀ54.6, 41.9; Cm 130.1d,
129.9d, J(PC)ꢀ11.4, 9.9.
/
N)ꢀ
/
1605m cmꢂ1. FAB-MS: m/z 1495
/
(cis-Ph2PCHÄ
/
CHPPh2)ꢂ
/
Pd]ꢁ. LMꢀ
/
1
/
the HCÄ
/
N, C6 and C1 carbons, evidencing formation of
/
the cyclometallated ring [39,40].
The synthesis of complexes 2 and 8 has been described
previously by us [30]. Reaction of 2 and 8 with the
tertiary monophosphines PPh3, P(p-MeOC6H4)3 and
P(p-NMe2C6H4)Ph2 gave the doubly cyclometallated
/
/
/
/
complexes [1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
(PR3)}2C6H4] (PR3ꢀPPh3, 4; P(p-MeOC6H4)3, 5; P(p-
NMe2C6H4)Ph2, 6) and [1,4-{Pd[2,3,4-(MeO)3C6HC-
(H)ÄNCH2](Cl)-(PR3)}2C6H4] (PR3ꢀPPh3, 9; P(p-
/
NCH2](Cl)-
/
/
/
/
/
/
/
/
/
MeOC6H4)3, 10; P(p-NMe2C6H4)Ph2, 11), respectively,
which were fully characterized (see Section 2). The
spectroscopic features of these complexes are similar to
those described for 3. Thus, the IR spectra was in
/
/
/
/
accordance with coordination of the HCÄ
/
N group. The
1H NMR spectra showed the coupling of the HCÄ
/N
3. Results and discussion
and H5 resonances to the 31P nucleus and the 13C{1H}
NMR spectra also showed the high-frequency shift of
For the convenience of the reader the compounds and
reactions are shown in Schemes 1 and 2. The com-
pounds described in this paper were characterized by
elemental analysis (C, H, N) and by IR spectroscopy
the resonances corresponding to the HCÄ
/
N, C6 and C1
carbons. In all the cases, the FAB-MS rendered clusters
of peaks whose isotopic patterns were in agreement with
[M]ꢁ and/or [MꢂPR3]ꢁ fragments.
/
1
and by H, 31P{1H} NMR and, in part, 13C{1H} NMR
The reaction of the 4 with PPh3 in a 1:2 molar ratio
did not yield the expected non-cyclometallated complex,
with two phosphine ligands coordinated to palladium
spectroscopy and FAB mass spectrometry (data in the
Section 2).
The reaction of complex 1 [30] with triphenylpho-
sphine in a 1:2 molar ratio gave the doubly cyclometal-
and the PdÃ
/
N bond cleaved [37,41]. The 1H NMR
spectra of the reaction mixture in CDCl3 showed the
lated
complex
[1,3-{Pd[2,3,4-(MeO)3C6HC(H)Ä
/
resonances corresponding to the HCÄ
/
N and H5 reso-
nances as singlets (no coupling to the 31P nucleus was
observed). This behavior is characteristic of the non-
NCH2](OAc)(PPh3)}2C6H4] (3), after cleavage of the
two acetate-bridging ligands. The IR spectrum of 3
showed the n(CÄ
/
N) stretch at 1610 cmꢂ1, shifted to
cyclometallated complexes, where in the absence of PdÃ
/

M. Lo´pez-Torres et al. / Polyhedron 21 (2002) 2063Á
/2069
2067
Scheme 1. (i) NaCl (acetone/water); (ii) PR3 (acetone); (iii) 1: cis-dppe; 2: NaClO4 (acetone/water).
Scheme 2. (i) PR3 (acetone); (ii) 1: cis-dppe; 2: NaClO4 (acetone/water).

2068
M. Lo´pez-Torres et al. / Polyhedron 21 (2002) 2063Á2069
/
Scheme 3.
N bond the metallated ring can rotate about the PdÃ
/
C
(Proyecto PGIDT99PXI20907B) and the Universidad
de la Coruna for financial support.
˜
vector so that its plane is at 908 to the palladium
coordination plane and coupling of the H5 proton to the
31P nucleus is absent [37,41]. Furthermore, the 31P{1H}
spectrum did not show the expected singlet. In order to
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/
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Acknowledgements
We thank the Ministerio de Educacio´n y Cultura
(Proyecto PB98-0638-C02-01/02), the Xunta de Galicia

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