Cyclopalladated compounds with bridging and chelating diphosphine ligands. Effect of ring size. Crystal and molecular structure of [{Pd[4-(COH)C6H3C(H)=N(Cy)-C2,N] (C1)}2(μ-Ph2PCH2PPh2)]

Article abstract of DOI:10.1016/S0277-5387(02)01170-1

Treatment of the chloro-bridged dinuclear compound [{Pd[4-(COH)C₆H₃C(H)=N(Cy)-C2,N]}(μ-Cl)]₂ (1) with tertiary diphosphines in 1:1 molar ratio gave [{Pd[4-(COH)C₆H₃C(H)=N(Cy)-C2,N] (Cl)}₂(μ-Ph₂PRPPh₂)] (R: CH₂, 2; CH₂CH₂, 3; (CH₂)₄, 4; (CH₂)₆, 5: Fe(C₅H₄)₂, 6; trans-CH=CH, 7; C≡C, 8) with the diphosphine in a bridging mode. When the reaction was carried out in a 1:2 molar ratio in the presence of NH₄PF₆, the compounds [Pd{4-(COH)C₆H₃C(H)=NCy-C2,N} (Ph₂PRPPh₂-P,P)][PF₆] (R: CH₂, 9; CH₂CH₂, 10; (CH₂)₄, 11; (CH₂)₆, 12; Fe(C₅H₄)₂, 13; 1,2-C₆H₄, 14; cis-CH=CH, 15; NH, 16) with the diphosphine chelated to the palladium atom, were obtained. ¹H, ³¹P-{¹H} and ¹³C- {¹H} NMR, IR and mass spectroscopic data are given. The crystal structure of compound 2 has been determined by X-ray crystallography.

Full text of DOI:10.1016/S0277-5387(02)01170-1

Polyhedron 21 (2002) 2309ꢀ2315
/
www.elsevier.com/locate/poly
Cyclopalladated compounds with bridging and chelating diphosphine
ligands. Effect of ring size. Crystal and molecular structure of
[{Pd[4-(COH)C6H3C(H)ÄN(Cy)-C2,N](Cl)}2(m-Ph2PCH2PPh2)]
/
Raquel Ares a, Margarita Lo´pez-Torres a, Alberto Ferna´ndez a, Samuel Castro-Juiz a,
Antonio Suarez a, Gemma Alberdi b, Jesu´s J. Ferna´ndez a,*, Jose´ M. Vila b,*
a Departamento de Qu´ımica Fundamental, Universidad de A Coruna, 15071 A Coruna, Spain
˜
˜
b Departamento de Qu´ımica Inorga´nica, Universidad de Santiago de Compostela, 15782 Santiago de Compostela, Spain
Received 17 May 2002; accepted 23 July 2002
Abstract
Treatment of the chloro-bridged dinuclear compound [{Pd[4-(COH)C6H3C(H)Ä
sphines in 1:1 molar ratio gave [{Pd[4-(COH)C6H3C(H)ÄN(Cy)-C2,N](Cl)}2(m-Ph2PRPPh2)] (R: CH2, 2; CH2CH2, 3; (CH2)4, 4;
(CH2)6, 5; Fe(C5H4)2, 6; trans-CHÄCH, 7; CÅC, 8) with the diphosphine in a bridging mode. When the reaction was carried out in a
1:2 molar ratio in the presence of NH4PF6, the compounds [Pd{4-(COH)C6H3C(H)ÄNCy-C2,N}(Ph2PRPPh2-P,P)][PF6] (R: CH2,
9; CH2CH2, 10; (CH2)4, 11; (CH2)6, 12; Fe(C5H4)2, 13; 1,2-C6H4, 14; cis-CHÄCH, 15; NH, 16) with the diphosphine chelated to the
palladium atom, were obtained. 1H, 31Pꢀ{1H} and 13Cꢀ{1H} NMR, IR and mass spectroscopic data are given. The crystal structure
/
N(Cy)-C2,N]}(m-Cl)]2 (1) with tertiary dipho-
/
/
/
/
/
/
/
of compound 2 has been determined by X-ray crystallography.
# 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Palladium; Metallation; Schiff base; Phosphorus ligands; X-ray diffraction
1. Introduction
ring size; by far the most well-studied examples are five-
membered palladacycles containing nitrogen donor
organic substrates [8].
Our interest in cyclometallated systems has been
centred, among others, in palladium(II) compounds
derived from differently substituted bidentate [C,N]
Schiff bases [9], ferrocenylimines [10] or substituted
The synthesis of cyclometallated compounds has seen
a growing interest in the last decades and numerous
articles and reviews concerning their properties have
been reported. The interest of chemists in this type of
compounds derives from their novel and outstanding
applications, such as for instance, to serve as intermedi-
ates in organic and organometallic synthesis [1], as
active catalysts [2], as liquid crystals [3] or as analytical
tools [4], to allow the resolution of racemic mixtures [5],
or to be useful in the design of metal complexes with
promising photochemical [6] or anticancer properties [7].
Cyclometallated compounds are usually classified ac-
cording to the metal, to the donor atom, or to chelate
imidazoles [11], as well as derivatives of [C,N,X] (Xꢁ
/
N, O, S) terdentate ligands [12]. We have reported that
Schiff bases derived from 1,4-(COH)2C6H4 (terephtha-
laldehyde), potentially tetradentate ligands, give rise to
different cyclopalladated species depending on the
reaction conditions [13,14]. Thus, treatment of 1,4-
(CyNꢁ
acetic acid afforded the monocyclometallated complex
[Pd{4-(COH)C6H3C(H)ÄN(Cy)-C2,N}(m-O2CMe)]2 in
which the acidic nature of the solvent caused hydrolysis
of one of the CÄN double bonds, the second imine
/
CH)2C6H4 with palladium(II) acetate in glacial
/
* Corresponding authors. Tel.: ꢂ
81-595-012 (J.M.V.). Tel.: ꢂ34-981-167-000; fax: ꢂ
(J.J.F.)
/
34-981-563-100x14255; fax: ꢂ
/
34-
/
/
/34-981-167-065
group being stabilized by palladium coordination. An
interesting finding in this novel compound is its
functionalization with a free formyl group on the
E-mail addresses: lujjfs@udc.es (J.J. Ferna´ndez), qideport@usc.es
(J.M. Vila).
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 7 0 - 1

2310
R. Ares et al. / Polyhedron 21 (2002) 2309ꢀ2315
/
metallated phenyl ring. In the present paper, we report
the synthesis and characterization of new examples of
mono- and polynuclear cyclometallated compounds of
palladium(II) derived from terephthalbenzylidenimines
with diphosphine ligands.
1692s, n(CÄ
[LPd(PP)]ꢂ. NMR 1H: 9.20 (s, Ha), 4.51 (t, CH2P,
2J(PH)ꢁ10.8 Hz). NMR 31Pꢀ{1H}: 36.98 (s).
/
N): 1622m. FAB Mass: 1075 [Mꢃ
/
Cl]ꢂ, 718
/
/
2.2.1.2. [{Pd[4-(COH)C6H3C(H)Ä
C2,N](Cl)}2{m-Ph2P(CH2)4PPh2}] (4). Yield: 91%.
Anal. Found: C, 58.3; H, 5.0; N, 2.3.
C56H60Cl2N2O2P2Pd2×(CHCl3)0.15 requires: C, 58.3; H,
5.2; N, 2.4%. IR: n(CÄO): 1695s, n(CÄN): 1622m. FAB
Mass: 1103 [Mꢃ
Cl]ꢂ, 746 [LPd(PP)]ꢂ, 718 [(Lꢃ
COH)Pd(PP)]ꢂ. NMR H: 9.20 (s, Ha), 8.14 (dd, Hi,
4J(PHi)ꢁ8.3 Hz, 5J(HiH7)ꢁ
1.0 Hz), 6.79 (dd, H3,
4J(PH3)ꢁ5.6 Hz, 4J(H3H5)ꢁ
NMR 31Pꢀ{1H}: 33.78 (s). NMR 13Cꢀ
COH), 170.0 (d, CÄ
/N(Cy)-
2. Experimental
/
/
/
2.1. Materials and instrumentation
/
/
1
All solvents were distilled prior to use from appro-
priate drying agents [15]. Chemicals were used as
supplied from commercial sources. Elemental analyses
(C, H, N) were carried out in a Carlo-Erba 1108
elemental analyser. IR spectra were recorded as KBr
/
/
/
/
1.2 Hz), 4.52 (m, CH2P).
/
/
{1H}: 192.2 (s,
4
/
N, J(PC)ꢁ
/4.3 Hz), 157.9 (s, C1),
4
154.4 (s, C2), 135.7 (d, C4, J(PC)ꢁ5.0 Hz), 135.3 (d,
C3, J(PC)ꢁ
130.0 (d, Ci, J(PC)ꢁ
/
3
2
pellets or Nujol mulls on a Perkinꢀ
photometer. NMR spectra were obtained as CDCl3
solutions and referenced to SiMe4 (1H, 13Cꢀ{1H}) or
85% H3PO4 (31Pꢀ{1H}), and were recorded on a Bruker
AC-200F spectrometer (200.0 MHz for H, 50.3 MHz
for 13Cꢀ{1H}, 81.0 MHz for 31Pꢀ{1H}). Mass spectra
/
Elmer 1330 spectro-
/
9.9 Hz), 133.9 (d, Co, J(PC)ꢁ11.4 Hz),
/
1
3
/
46.1 Hz), 128.6 (d, Cm, J(PC)ꢁ
/
/
10.6 Hz), 127.4 (s, C5), 124.3 (s, C6), 62.8 (s, C7), 33.5 (s,
1
/
C8, C12), 29.7 (d, CH2P, J(PC)ꢁ
CH2CH2P, 2J(PC)ꢁ
17.8 Hz), 25.8 (s, C10), 25.4 (s, C9,
C11).
/
33.4 Hz), 26.4 (d,
1
/
/
/
were obtained in a QUATRO mass spectrometer with
Cs ion-gun and 3-NBA matrix. Conductivity measure-
ments were made on a Crison GLP 32 conductivimeter
using 10ꢃ3 M solutions in dry acetonitrile at room
temperature (r.t., 298 K). The synthesis of [Pd{4-
2.2.1.3. [{Pd[4-(COH)C6H3C(H)Ä
C2,N](Cl)}2{m-Ph2P(CH2)6PPh2}] (5). Yield: 64%.
Anal. Found: C, 60.5; H, 5.0; N, 1.2.
C58H64Cl2N2O2P2Pd2×(Me2CO)0.15 requires: C, 60.4;
H, 5.6; N, 1.2%. IR: n(CÄO): 1687s, n(CÄN): 1622m.
FAB Mass: 1166 [M]ꢂ, 1130 [MꢃCl]ꢂ, 774
[LPd(PP)]ꢂ. NMR 1H: 9.22 (s, Ha), 8.15 (dd, Hi,
4J(PHi)ꢁ8.3 Hz, 5J(HiH7)ꢁ
1.0 Hz), 6.83 (dd, H3,
4J(PH3)ꢁ5.2 Hz, 4J(H3H5)ꢁ
1.5 Hz), 4.50 (m, CH2P).
NMR 31Pꢀ{1H}: 33.69(s).
/
N(Cy)-
/
(COH)C6H3C(H)Ä
/
N(Cy)-C2,N}(m-Cl)]2 (1) was re-
/
/
ported in a recent paper from this laboratory [13].
/
2.2. Synthesis of the complexes
/
/
/
/
2.2.1. Syntheses of [{Pd[4-(COH)C6H3C(H)Ä
/
N(Cy)-
/
C2,N](Cl)}2(m-Ph2PCH2PPh2)] (2)
To a solution of 1 (25.00 mg, 0.035 mmol) in acetone
(ca. 10 cm3), Ph2PCH2PPh2 (dppm, 12.13 mg, 0.032
mmol) was added. The mixture was stirred for 12 h at
r.t., after which the precipitate formed was filtered off,
dried in vacuo, and recrystallized from chloroform/n-
hexane to yield the desired product as pale yellow
microcrystals. Yield: 42% (14.68 mg). Anal. Found: C,
57.9; H, 4.9; N, 2.7. C53H54Cl2N2O2P2Pd2 requires: C,
2.2.1.4. [{Pd[4-(COH)C6H3C(H)Ä
/
N(Cy)-
C2,N](Cl)}2{m-(Ph2PC5H4)2Fe}] (6). Yield: 58%.
Anal. Found: C, 50.2; H, 4.3; N, 1.9. C62H58Cl2FeN2-
O2P2Pd2×
IR: n(CÄ
[Mꢃ
Cl]ꢂ, 874 [LPd(PP)]ꢂ, 845 [(Lꢃ
/
(CHCl3)2.75 requires: C, 50.6; H, 4.0; N, 1.8%.
O): 1698s, n(CÄN): 1622m. FAB Mass: 1229
COH)Pd(PP)]ꢂ.
/
/
/
/
1
4
NMR H: 9.12 (s, Ha), 8.17 (dd, Hi, J(PHi)ꢁ
5J(HiH7)ꢁ1.0 Hz), 6.59 (dd, H3, 4J(PH3)ꢁ
4J(H3H5)ꢁ
31Pꢀ{1H}: 31.40 (s).
/
8.8 Hz,
/
/
5.9 Hz,
58.0; H, 5.0; N, 2.6%. IR: n(CÄ
1621m. FAB Mass: 1061 [Mꢃ
Cl]ꢂ, 1033 [Mꢃ
COH]ꢂ, 704, [LPd(PP)]ꢂ, 676 [LPdCl]ꢂ. NMR 1H:
9.07 (s, Ha), 7.38 (dd, H5, 3J(H5H6)ꢁ
7.9 Hz,
1.2 Hz), 6.88 (dd, H3, J(PH3)ꢁ4.9 Hz),
5.03 (t, CH2P, 2J(PH)ꢁ13.4 Hz). NMR 31Pꢀ{1H}:
30.90 (s).
Compounds 3ꢀ
corresponding diphosphine ligand as appropriate.
/
O): 1692s, n(CÄ
/
N):
/1.0 Hz), 5.00, 4.60 (m, Hferrocene). NMR
/
/
Clꢃ
/
/
/
2.2.1.5. [{Pd[4-(COH)C6H3C(H)Ä
/
N(Cy)-
4
4J(H3H5)ꢁ
/
/
C2,N](Cl)}2{m-trans(Ph2PCHÄCHPPh2)}]
/
(7).
/
/
Yield: 20%. Anal. Found: C, 54.2; H, 4.7; N, 2.6.
C54H54Cl2N2O2P2Pd2×(Me2CO)0.85 requires: C, 54.4; H,
4.6; N, 2.3%. IR: n(CÄ
Mass: 1073 [Mꢃ
Cl]ꢂ, 1045 [Mꢃ
/
/
8 were prepared similarly, using the
/
O): 1697m, n(CÄ
/
N): 1619m. FAB
/
/
Clꢃ
/
COH]ꢂ, 716
[LPd(PP)]ꢂ, 687[(L-COH)Pd(PP)]ꢂ. NMR H: 9.20 (s,
1
2.2.1.1. [{Pd[4-(COH)C6H3C(H)Ä
/N(Cy)-
Ha), 8.18 (dd, Hi, 4J(PHi)ꢁ
Hz), 7.00 (at, CHÄCH, Nꢁ39.5 Hz), 6.81 (dd, H3,
4J(PH3)ꢁ4.8 Hz, 4J(H3H5)ꢁ1.0 Hz). NMR 31Pꢀ
{1H}: 34.59 (s).
/
8.3 Hz, 5J(HiH7)ꢁ
1.0
/
C2,N](Cl)}2(m-Ph2PCH2CH2PPh2)] (3). Yield: 85%.
Anal. Found: C, 58.7; H, 4.8; N, 2.4. C54H56Cl2N2O2-
/
/
/
/
/
P2Pd2 requires: C, 58.4; H, 5.1; N, 2.5%. IR: n(CÄ
/O):

R. Ares et al. / Polyhedron 21 (2002) 2309ꢀ
/2315
2311
4
4
2.2.1.6. [{Pd[4-(COH)C6H3C(H)Ä
/
N(Cy)-
(m, H3, J(PbH3)ꢁ
/
7.8 Hz, J(PaH3)ꢁ
/
5.4 Hz). NMR
C2,N](Cl)}2(m-Ph2PCCPPh2)] (8). Yield: 50%. Anal.
Found: C, 58.7; H, 4.6; N, 2.4. C54H52Cl2N2O2P2Pd2
31Pꢀ{1H}: 61.24 (d, Pa, 2J(PP)ꢁ
/
/
26.3 Hz), 45.23(d, Pb).
requires: C, 58.6; H, 4.7; N, 2.5%. IR: n(CÄ
n(CÄ
N): 1626m. FAB Mass: 1106 [M]ꢂ, 714
[LPd(PP)]ꢂ. NMR 1H: 9.24 (s, Ha), 8.12 (dd, Hi,
4J(PHi)ꢁ8.9 Hz, 5J(HiH7)ꢁ
1.0 Hz), 6.92 (dd, H3,
4J(PH3)ꢁ7.3 Hz, 4J(H3H5)ꢁ1.0 Hz). NMR 31Pꢀ
{1H}: 14.46(s).
/
O): 1698s,
2.2.2.2. [Pd{4-(COH)C6H3C(H)Ä
/
N(Cy)-
/
C2,N}{Ph2P(CH2)4PPh2-P,P}][PF6] (11). Yield:
49%. Anal. Found: C, 56.3; H, 4.9; N, 1.7. C42H44F6-
/
/
NOP3Pd requires: C, 56.5; H, 5.0; N, 1.6%. IR: n(CÄ
1696s, n(CÄ
Cy]ꢂ. NMR 1H: 9.33 (s, Ha), 8.48 (d, Hi, 4J(PaHi)ꢁ
/
O):
/
/
/
/
N): 1622m. FAB Mass: 746 [M]ꢂ, 663 [Mꢃ
/
/
7.5
Hz). NMR 31Pꢀ
19.87(d, Pb).
/
{1H}: 32.19 (d, Pa, J(PP)ꢁ
/
29.1 Hz),
2
2.2.2. Syntheses of [Pd{4-(COH)C6H3C(H)Ä
/N(Cy)-
C2,N}(Ph2PCH2PPh2-P,P)][PF6] (9)
2.2.2.3. [Pd{4-(COH)C6H3C(H)Ä
/
N(Cy)-
To a solution of 1 (20.00 mg, 0.028 mmol) in acetone
(ca. 15 cm3), dppm (21.56 mg, 0.056 mmol) was added.
The mixture was stirred for 2 h at r.t., after which
ammonium hexafluorophosphate (13.69 mg, 0.084
mmol) was added, the resultant solution was stirred
for a further 1 h, water (ca. 40 cm3) was added dropwise
and the resulting mixture stirred for 2 h. The precipitate
C2,N}{Ph2P(CH2)6PPh2-P,P}][PF6] (12). Yield:
74%. Anal. Found: C, 53.2; H, 5.2; N, 1.6. C44H48F6-
NOP3Pd requires: C, 53.4; H, 5.3; N, 1.5%. IR: n(CÄ
1694s, n(CÄ
N): 1624m. FAB Mass: 774 [M]ꢂ, 663 [Mꢃ
COHꢃ
Cy]ꢂ. NMR 1H: 9.28 (s, Ha), 8.40 (b, Hi). NMR
31Pꢀ{1H}: 33.12 (b, Pa), 18.37 (b, Pb).
/
O):
/
/
/
/
formed was filtered off, washed with water (2ꢄ
5 cm3)
/
2.2.2.4. [Pd{4-(COH)C6H3C(H)Ä
/
N(Cy)-
and dried in vacuo. The desired complex was recrystal-
lized from chloroform/n-hexane as pale yellow micro-
crystals. Yield: 92% (43.72 mg). Anal. Found: C, 56.3;
C2,N}{(Ph2PC5H4)2Fe-P,P}][PF6] (13). Yield: 34%.
Anal. Found: C, 56.5; H, 3.9; N, 1.2. C48H42F6Fe-
NOP3Pd requires: C, 56.6; H, 4.2; N, 1.4%. IR: n(CÄ
1697s, n(CÄN): 1609m. FAB Mass: 790 [Mꢃ
Cy]ꢂ, 291
[(L-COH)Pd]ꢂ. NMR H: 9.26 (s, Ha), 6.88 (m, H3),
4.78, 4.65, 4.31, 3.59 (d, Hferrocene). NMR 31Pꢀ{1H}:
/
O):
H, 3.7; N, 1.4. C39H38F6NOP3Pd×
56.0; H, 5.2; N, 1.5%. IR: n(CÄ
1620m. FAB Mass: 704 [M]ꢂ, 676 [Mꢃ
/
(Me2CO)2 requires: C,
O): 1689s, n(CÄN):
COH]ꢂ. NMR
1H: 9.51 (s, Ha), 8.41 (d, Hi, J(PaHi)ꢁ
7.3 Hz), 7.09
(m, H3, 4J(PbH3)ꢁ9.5 Hz, 4J(PaH3)ꢁ
7.3 Hz,
4J(H3H5)ꢁ1.2 Hz), 4.31 (dd, CH2P, 2J(PH)ꢁ
11.8,
11.2 Hz). NMR 31Pꢀ
4.98 (d, Pa, J(PP)ꢁ65.7
Hz), ꢃ
28.16 (d, Pb). NMR 13Cꢀ{1H}: 191.6 (s, COH),
175.4 (m, CÄ 127.8 Hz,
N), 161.6 (dd, C2, 2J(PbC)ꢁ
2J(PaC)ꢁ9.4 Hz), 154.0 (d, C1, 3J(PbC)ꢁ
2.1 Hz),
137.0 (dd, C4, 4J(PbC)ꢁ
6.3 Hz),
136.6 (dd, C3, 3J(PbC)ꢁ
3.5 Hz),
/
/
/
/
1
/
/
4
/
2
39.93 (d, Pa, J(PP)ꢁ
/
30.9 Hz), 23.15(d, Pb).
/
/
/
/
2.2.2.5. [Pd{4-(COH)C6H3C(H)Ä
/
N(Cy)-C2,N}{1,2-
2
/
{1H}: ꢃ
/
/
(Ph2P)2C6H4-P,P}][PF6] (14). Yield: 48%. Anal.
Found: C, 57.9; H, 4.1; N, 1.4. C44H40F6NOP3Pd
/
/
/
/
requires: C, 57.9; H, 4.4; N, 1.5%. IR: n(CÄ
/
O):
N): 1615m. FAB Mass: 766 [M]ꢂ, 738
/
/
1694m, n(CÄ
/
/
8.5 Hz, 4J(PaC)ꢁ
/
[Mꢃ
/
COH]ꢂ, 684 [Mꢃ
/
COHꢃ
/
Cy]ꢂ, 291 [(Lꢃ
/
/
12.7 Hz, 3J(PaC)ꢁ
/
COH)Pd]ꢂ. NMR 1H: 9.45 (s, Ha), 8.56 (d, Hi,
2
2
133.9 (d, Co, J(PC)ꢁ
/
13.5 Hz), 133.5 (d, Co, J(PC)ꢁ
/
3
4J(PaHi)ꢁ
4J(H3H5)ꢁ
4J(PaH3)ꢁ6.0 Hz). NMR 31Pꢀ
2J(PP)ꢁ
25.4 Hz), 42.95(d, Pb).
/
8.8 Hz), 7.74 (dd, H5, J(H5H6)ꢁ
/
7.5 Hz,
4
12.8 Hz), 133.0 (d, Cp, J(PC)ꢁ
4J(PC)ꢁ2.8 Hz),129.8 (d, Cm, 3J(PC)ꢁ
(s, C5), 128.8 (d, Cm, J(PC)ꢁ
/
2.8 Hz), 132.3 (d, Cp,
4
/
1.5 Hz), 7.15 (m, H3, J(PbH3)ꢁ8.1 Hz,
{1H}: 55.89 (d, Pa,
/
/
/
12.1 Hz), 129.5
/
/
3
/10.6 Hz), 128.3 (b, C6),
/
1
2
70.0 (s, C7), 127.5 (dd, Ci, J(PC)ꢁ
/
31.6 Hz, J(PC)ꢁ
/
1
2
4.9 Hz), 124.8 (dd, Ci, J(PC)ꢁ
Hz), 41.4 (dd, CH2P, 1J(PaC)ꢁ27.7 Hz, 1J(PbC)ꢁ
Hz), 33.2 (s, C8, C12), 24.9 (s, C10), 24.7 (s, C9, C11).
Compounds 10ꢀ16 were prepared similarly, but using
/
50.3 Hz, J(PC)ꢁ
/
4.9
2.2.2.6. [Pd{4-(COH)C6H3C(H)Ä
Ph2PCHÄCHPPh2-P,P)][PF6] (15). Yield: 51%.
Anal. Found: C, 55.5; H, 4.1; N, 2.0. C40H38F6NOP3Pd
requires: C, 55.7; H, 4.4; N, 1.6%. IR: n(CÄO): 1694m,
n(CÄ
N): 1609m. FAB Mass: 716 [M]ꢂ, 688 [Mꢃ
COH]ꢂ, 291 [(Lꢃ
/
N(Cy)-C2,N}(cis-
/
/
20.4
/
/
/
the corresponding diphosphine ligand as appropriate, in
a 1/diphosphine 1:2 molar ratio.
/
/
1
/
COH)Pd]ꢂ. NMR H: 9.59 (s, Ha),
8.54 (d, Hi, J(PaHi)ꢁ
8.8 Hz). NMR 31Pꢀ{1H}: 63.85
11.0 Hz), 55.02(d, Pb).
4
/
/
2
2.2.2.1. [Pd{4-(COH)C6H3C(H)Ä
/N(Cy)-
(d, Pa, J(PP)ꢁ
/
C2,N}{Ph2P(CH2)2PPh2-P,P}][PF6] (10). Yield:
56%. Anal. Found: C, 55.7; H, 4.8; N, 1.5.
2.2.2.7. [Pd{4-(COH)C6H3C(H)Ä
/
N(Cy)-
C40H40F6NOP3Pd×
N, 1.5%. IR: n(CÄ
Mass: 718 [M]ꢂ, 690 [Mꢃ
/
(Me2CO) requires: C, 55.9; H, 4.9;
C2,N}(Ph2PNHPPh2-P,P)][PF6] (16). Yield: 86%.
Anal. Found: C, 53.8; H, 4.7; N, 3.2. C38H37F6N2OP3Pd
/
O): 1695s, n(CÄ
/
N): 1614m. FAB
/
COH]ꢂ, 383[LPd]ꢂ. NMR
requires: C, 53.6; H, 4.4; N, 3.3%. IR: n(CÄ
n(CÄ
N): 1612m. FAB Mass: 705 [M]ꢂ, 677 [Mꢃ
COH]ꢂ. NMR 1H: 9.68 (s, Ha), 8.33 (d, Hi,
/
O): 1694m,
1H: 9.42 (s, Ha), 8.48 (d, Hi, J(PaHi)ꢁ
/
7.8 Hz), 7.85
1.0 Hz), 7.09
/
/
4
3
4
(dd, H5, J(H5H6)ꢁ
/
7.4 Hz, J(H3H5)ꢁ
/

2312
R. Ares et al. / Polyhedron 21 (2002) 2309ꢀ2315
/
4J(PaHi)ꢁ
44.40 (d, Pa, 2J(PP)ꢁ
13Cꢀ{1H}: 191.6 (s, COH), 174.5 (m, CÄ
C1, 3J(PbC)ꢁ2.2 Hz), 137.1 (dd, C4, 4J(PbC)ꢁ
Hz, 4J(PaC4)ꢁ2.1 Hz), 133.1 (d, Co, 2J(PC)ꢁ
13.5 Hz),
132.5 (d, Co, 2J(PC)ꢁ14.9 Hz), 129.5 (d, Cm, 3J(PC)ꢁ
/
7.3 Hz), 6.14 (m, H3). NMR 31Pꢀ
67.8 Hz), 33.30 (d, Pb). NMR
N), 153.7 (d,
13.5
/
{1H}:
described in this paper were characterized by elemental
analysis (C, H, N), mass spectrometry, and by IR and
/
/
/
1H, 31Pꢀ
scopy (data in Section 2).
Reaction of [Pd{4-(COH)C6H3C(H)Ä
/
{1H} and (in part) 13Cꢀ{1H} NMR spectro-
/
/
/
/
/
/N(Cy)-C2,N}-
/
/
(m-Cl)]2 (1) [13] with bis(diphenylphosphino)methane
(dppm), 1,2-bis(diphenylphosphino)ethane (dppe), 1,4-
bis(diphenylphosphino)butane (dppb), 1,6-bis(diphenyl-
phosphino)hexane (dpph), 1,1?-bis(diphenylphosphi-
no)ferrocene (dppf), trans-bis(diphenylphosphino)-
ethene (trans-dppe), or bis(diphenylphosphino)acetylene
(dppac) in a 1:1 molar ratio, in acetone at room
temperature afforded the polinuclear complexes
3
11.4 Hz), 127.9 (d, Cm, J(PC)ꢁ12.1 Hz), 70.1 (s, C7),
/
33.5 (s, C8, C12), 25.0 (s, C10), 24.7 (s, C9, C11)
2.3. X-ray crystallographic study
Three-dimensional, room temperature X-ray data
were collected on a Siemens SMART CCD diffract-
ometer by the omega scan method. Reflections were
measured from a hemisphere of data collected of frames
each covering 0.3 degrees in omega. Of the 18879
reflections measured, all of which were corrected from
Lorentz and polarisation effects and for absorption by
semi-empirical methods based on symmetry-equivalent
and repeated reflections (max./min. transmissions;
0.87,0.80), 3263 independent reflections exceeded the
[{Pd[4-(COH)C6H3C(H) Ä
Ph2PRPPh2)] (R: CH2, 2; CH2CH2, 3; (CH2)4, 4; (CH2)6,
5; Fe(C5H4)2, 6; trans-CHÄCH, 7; CÅC, 8) in which the
/
N(Cy)-C2 ,N ](Cl)}2(m-
/
/
diphosphine is acting as a bridging ligand. The new
compounds were air-stable and soluble in the more
common solvents, such as toluene, chloroform, acetone
or ethanol, and gave satisfactory elemental analysis (see
Experimental section). The MS FAB spectra showed
similar fragmentation patterns, containing peaks as-
significance level IFI/sIFI ꢀ4.0. The structure was
/
signed to, among others, [M]ꢂ, [Mꢃ
/
Cl]ꢂ, [Mꢃ
/
Clꢃ
/
solved by direct methods and refined by full matrix
least squares on F2. Hydrogen atoms were included in
calculated positions and refined in riding mode. Refine-
COH]ꢂ and [LPd(PP)]ꢂ, after consideration of the
palladium isotopes [17], thereby confirming the dinuc-
lear (2ꢀ5, 7, 8) and trinuclear (6) nature of these
/
ment converged at a final Rꢁ
/
0.0588 (wR2ꢁ0.1310, for
/
complexes. The IR spectra showed the shift of the CÄ
/
all 7131 unique data; 285 parameters, mean and max-
imum d/s 0.000, 0.000), with allowance for the thermal
anisotropy of all non-hydrogen atoms. Minimum and
N stretch towards lower wavenumbers, as compared to
the free Schiff base ligand (1638 vs. ca. 1620 cmꢃ1),
indicating N-coordination of the CÄ
n(CÄO) band in the range 1698ꢀ
assigned to the free formyl group [19]. The 31Pꢀ
NMR spectra showed a singlet in the range d 38ꢀ
/
N group [18]. A
1687 cmꢃ1 was
{1H}
30,
maximum final electron density ꢃ0.458 and 1.440 e
/
/
/
Aꢃ3 The structure solution and refinement were carried
out using the program package SHELX-97 [16].
/
/
shifted to higher frequency from the spectrum of the free
phosphine, in agreement with phosphorus coordination
to the metal center and indicated that the two phospho-
rus nuclei are equivalent [20].
3. Results and discussion
In the 1H NMR spectrum for complexes 3ꢀ
8 the
/
For the convenience of the reader the compounds and
reactions are shown in Scheme 1. The compounds
COH group gave rise to a singlet ca. d 9.20, shifted to
lower field from the starting product, ca. 0.8 ppm, due
to the shielding effect of the phosphine phenyl rings, in
agreement with a phosphorus trans to nitrogen arrange-
ment [21]. The HCÄ
/
N resonance ca. d 8.10 appeared as
a doublet of doublets due to coupling to the 31P nucleus
[4J(PHi) ca. 8.5 Hz] and with the NCH proton atom of
the cyclohexyl ring [5J(HiH7)ꢁ
1.0 Hz]. The H6 and H5
/
proton resonances were overlapped and could not be
adequately assigned, but in compound 2 the latter could
be clearly distinguished as a doublet of doublets at d
7.38 by coupling to H3 and H4. A doublet of doublets at
d 6.92ꢀ
/
6.59 was assigned to H3, with coupling to the
phosphorus nucleus [4J(PH3)ꢁ
/
4.8ꢀ7.3 Hz]. This reso-
/
nance was shifted to lower field from the starting
product ca. 1.2 ppm, due to the shielding effect of the
phosphine phenyl rings. The non-phenyl proton reso-
nances of the diphosphine ligands could be unambigu-
Scheme 1.

R. Ares et al. / Polyhedron 21 (2002) 2309ꢀ
/2315
2313
ously assigned: the CH2P resonances appeared as a
triplet at d 5.03 and d 4.51 in compounds 2 and 3,
Table 1
31P NMR parameters
respectively [2J(PH)ꢁ
13.4, 10.8 Hz, also respectively],
/
a
d(Pa )
DR
and as a multiplet ca. d 4.50 in compounds 4 and 5. For
complex 6 two multiplets at d 5.00 and d 4.60 were
assigned to the ferrocene protons, and in complex 7 the
9
10
11
12
13
14
15
16
ꢃ4.98
61.24
32.19
33.12
39.93
55.89
63.85
44.40
ꢃ44.28
ꢂ21.94
ꢃ7.11
ꢃ6.18
ꢂ0.63
ꢂ16.69
ꢂ24.55
ꢂ5.10
AA?XX? spin system of the PCHÄ
to an apparent triplet at d 7.00 [Nꢁ
The 13Cꢀ{1H} NMR spectrum of compound 4
showed a doublet at d 170.0 and two singlets at d
157.9 and d 154.4 assignable to the HCÄN, C1 and C2
/
CHP group gave rise
/39.5 Hz].
/
/
a
carbons, respectively, downfield shifted from the spec-
trum of the free ligand (ca. 12, 20 and 26 ppm, also
respectively) [22], thereby confirming that cyclometalla-
tion was maintained [13,23]. The C3 and C4 resonances
appeared as doublets at d 135.7 and d 135.3, respec-
Difference respect to an equivalent phosphorus in a non-chelated
analogue, [(CꢀN)Pd(PPh3)(Cl)] (PPh3 trans to nitrogen, d 39.30 ppm),
Ref. [13].
/
The singlet signal of the COH resonance was shifted
to lower field from the starting product by 0.3ꢀ0.7 ppm
due to the shielding effect of the PPh2 groups cis to
carbon. This was most noteworthy in compounds 11ꢀ
13, due to larger chelate ring size. The HCÄN resonance
/
tively, by coupling to the phosphorus nuclei [3J(PC3)ꢁ
9.9 Hz, 4J(PC4)ꢁ
5.0 Hz]. Two doublets at d 29.7 and d
26.4 were assigned to the CH2P and CH2CH2P carbon
atoms, respectively [1J(PC)ꢁ33.4 Hz, 2J(PC)ꢁ
17.8
/
/
/
/
/
/
1
in the H NMR spectra ca. 8.40 ppm appeared as a
doublet due to coupling with the 31P nucleus trans to
nitrogen. The H6 resonance was overlapped and could
not be assigned, but the H5 and H3 resonances were
clearly distinguished in some complexes (see Section 2).
Thus, a doublet of doublets at d 7.85 (10) and d 7.74(14)
was assigned to the H5 proton, and a multiplet at d
Hz, respectively]. The X-ray crystal structure determina-
tion of compound 2 (see below) confirmed the spectro-
scopic data.
Treatment of the chloro-bridged complex 1 with
dppm, dppe, dppb, dpph, dppf, cis-dppe, 1,2-bis(diphe-
nylphosphino)benzene (1,2-dppb) or bis(diphenylpho-
sphine)amine (dppa) in a 1:2 molar ratio in the presence
of NH4PF6 yielded the cyclometallated compounds
7.15ꢀ6.14 was assigned to H3, coupled to both phos-
/
phorus nuclei. Selective decoupling experiments allowed
the correct assignment of the corresponding coupling
[Pd{4-(COH)C6H3C(H)Ä
P,P)][PF6] (R: CH2, 9; CH2CH2, 10; (CH2)4, 11; (CH2)6,
12; Fe(C5H4)2, 13; 1,2-C6H4, 14; cis-CHÄCH, 15; NH,
16). The new compounds were air-stable and soluble in
/
N(Cy)-C2,N}(Ph2PRPPh2-
constants, e.g. for compound 9, trans-4J(PH3)ꢁ
/
9.5 Hz,
cis-4J(PH3)ꢁ
For complexes 9 and 16 the 13Cꢀ
were consistent with the proposed structure (see Section
/7.3 Hz.
/
/
{1H} NMR data
the more common solvents. The conductivity data (125ꢀ
/
150 Vꢃ1 cm2 molꢃ1 in 10ꢃ3 mol dmꢃ3 solutions in dry
acetonitrile) showed them to be 1:1 electrolytes [24]. The
MS FAB spectra showed, among others, the corre-
2). A multiplet, a doublet of doublets and a doublet ca.
d 175, d 161 and d 154 were assigned to the CÄ
/N, C2
and C1 carbon atoms, respectively, coupled to phos-
phorus. These resonances were shifted downfield from
the starting product ca. 17, 33 and 16 ppm, also
respectively. In the case of the C2 resonance, a large
coupling constant to the phosphorus nucleus trans to
sponding peaks assigned to [M]ꢂ, [MꢃCOH]ꢂ and/or
/
[Mꢃ
Cy]ꢂ (see Section 2). In the IR spectrum a broad
/
and strong band at 850 cmꢃ1 arising from the PF6
ꢃ
counterion [19] was observed.
The 31Pꢀ{1H} NMR spectra showed two doublets,
carbon was observed (3J(PbC)ꢁ
127.8 Hz). The dipho-
/
/
suggesting the two phosphorus atoms to be non-
equivalent. The assignment of the doublets was made
on the assumption that a ligand of greater trans
influence shifts the resonance of the phosphorus atoms
trans to it to lower frequency [20]. The 31P chemical
shifts were clearly influenced by ring size [25], and the
sphine phenyl carbon resonances, as well as those of the
cyclohexyl ring, could also be unambiguously assigned
(see Experimental Section).
4. Molecular structure of complex 2
corresponding data for compounds 10ꢀ16 are summar-
/
ized in Table 1. The four-membered ring compound 9
gave a negative DR, as well as the larger ring compounds
11 and 12. The five-membered ring compounds 10, 14
and 15 gave a positive DR. In the case of compounds 13
and 16 the effect of the ferrocene moiety and the
heteroatom in the phosphine backbone gave a slightly
positive DR.
Suitable crystals of the title compound were grown by
slowly evaporating a chloroform/n-hexane solution. The
labeling scheme for the compound is shown in Fig. 1.
The crystals consist of discrete molecules, separated by
normal van der Waals distances. Crystallographic data
and selected interatomic distances and angles are listed
in Tables 2 and 3.

2314
R. Ares et al. / Polyhedron 21 (2002) 2309ꢀ2315
/
Table 3
Selected bond lengths (A) and bond angles (8) for complex 2
Bond lengths
Pd(1)ꢀ
Pd(1)ꢀ
Pd(1)ꢀ
Pd(1)ꢀ
C(1)ꢀ
/
C(1)
N(1)
P(1)
2.014(5)
2.111(3)
2.268(1)
2.393(1)
1.414(6)
C(6)ꢀ
N(1)ꢀ
O(1)ꢀ
P(1)ꢀC(15)
/
C(7)
C(7)
C(14)
1.431(7)
1.271(6)
1.166(8)
1.844(3)
/
/
/
/
/Cl(1)
/
/
C(6)
Bond angles
C(1)ꢀPd(1)ꢀ
C(1)ꢀPd(1)ꢀ
P(1)ꢀPd(1)ꢀ
N(1)ꢀPd(1)ꢀ
C(7)ꢀN(1)ꢀPd(1)
/
/
N(1)
80.43(17) N(1)ꢀ
93.52(13) C(1)ꢀC(6)ꢀ
93.35(4) C(6)ꢀC(1)ꢀ
92.96(12) C(15)ꢀ
112.5(3) P(1)ꢀC(15)ꢀ
/
C(7)ꢀ
/
C(6)
119.3(4)
115.3(5)
112.4(4)
115.63(6)
121.6(3)
/
/P(1)
/
/
C(7)
/
/Cl(1)
/
/
Pd(1)
/
/
Cl(1)
/P(1)ꢀ
/
Pd(1)
P(1)#1
/
/
/
/
distortion most noticeable in the somewhat reduced
‘bite’ angle of the cyclometallated moiety consequent
upon chelation. The requirements of the five-membered
ring forces the bond angle N(1)ꢀ
/
Pd(1)ꢀC(1) to
/
80.43(17)8. The geometry around the palladium atom
is slightly distorted square-planar, the mean deviation
from the least squares plane (plane 1: Pd1, C1, N1, P1,
Fig. 1. Molecular structure of [{Pd[4-(COH)C6H3C(H)ÄN(Cy)-
C2,N](Cl)}2(m-Ph2PCH2PPh2)] (2), with labeling scheme. Hydrogen
atoms have been omitted for clarity.
/
˚
Cl1) is 0.0916 A.
The palladiumꢀ
/
nitrogen bond length in the metalla-
cycle, 2.111(3) A, is longer than the predicted single
The crystal structure of 2 comprises a half molecule
per asymmetric unit, and exhibits C2 symmetry about
the central methylene PCH2P group. The four-coordi-
nated palladium(II) is bonded to an adjacent ortho-
carbon atom and to the nitrogen atom of the imine
group of the deprotonated Schiff base ligand and to a
chlorine atom (trans to C2). A phosphorus atom from
the diphosphine ligand which bridges the two metal
centers, completes the metal coordination sphere. The
sum of angles about palladium is 360.268, with the
˚
˚
bond value of 2.011 A, based on the sum of covalent
2
radii for nitrogen(sp ) and palladium, 0.701 and 1.31 A,
˚
respectively [26], and reflects the trans influence of the
phosphorus atom [27]. The palladiumꢀ
/
carbon bond
length, 2.014(5) A, is within the expected value of
˚
˚
2.081 A (based on the sum of the covalent radii for
2
carbon(sp ) and palladium, 0.771 and 1.31 A, respec-
˚
tively), but longer than those found in related complexes
where partial multiple-bond character of the Pdꢀ
was proposed [11,28]. The PdꢀP bond distance, 2.268(1)
A, is shorter than the sum of the single bond radii for
/C bond
/
˚
Table 2
Crystal and structure refinement data for complex 2
˚
palladium and phosphorus (2.41 A), suggesting partial
double bond character similar to others reported earlier
˚
[29,30]. The PdꢀCl bond length, 2.393(1) A, is consistent
Formula
Mr
C53H54Cl2N2O2P2Pd2
1096.62
293(2)
/
with PdꢀCl distances found in related species [30,31] but
/
Temperature (K)
Wavelength (A)
Crystal system
Space group
Unit cell dimensions
a (A)
˚
longer than the sum of the covalent radii (2.30 A) as a
consequence of the trans influence of the C(phenyl)
carbon.
0.71073
monoclinic
C2/c
The mean deviations from the least squares planes
determined for the metallacycle (plane 2: Pd1, C1, C6,
C7, N1) and the metallated phenyl ring (plane 3: C1, C2,
24.474(4)
10.424(2)
20.531(4)
111.302(4)
4880.0(15)
4
b (A)
c (A)
˚
C3, C4, C5, C6) are 0.0122 and 0.0027 A, respectively.
b (8)
V (A3)
The angle between these planes is 5.38. The angles
between plane 1 and the previous planes are: plane 1/
plane 2: 6.28, and plane 1/plane 3: 11.48.
Z
Crystal size (mm)
m (mmꢃ1
0.25ꢄ0.15ꢄ0.15
0.954
71.22
)
2umax (8)
Reflections collected
Reflections independent
R [F, I ꢀ2s(I)]
18879
7131 (Rintꢁ0.0869)
0.0588
0.1310
5. Supplementary material
wR [F2 , all data]
Max. r (e A3)
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
1.440

R. Ares et al. / Polyhedron 21 (2002) 2309ꢀ
/2315
2315
Vila, R. Mosteiro, J.J. Ferna´ndez, Organometallics 21 (2002)
1304.
[10] J.M. Vila, E. Gayoso, M.T. Pereira, M. Marino, J. Mart´ınez, J.J.
˜
Data Centre, CCDC No. 185113 for compound 2.
Copies of this information may be obtained free of
charge from The Director, CCDC, 12 Union Road,
Ferna´ndez, A. Ferna´ndez, M. Lo´pez-Torres, J. Organomet.
Cambridge, CB2 1EZ, UK (fax: ꢂ44-1223-336033;
e-mail: mailto: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
/
Chem. 637ꢀ639 (2001) 577.
/
[11] M. Lousame, A. Ferna´ndez, M. Lo´pez-Torres, D. Va´zquez-
Garc´ıa, J.M. Vila, A. Sua´rez, J.M. Ortigueira, J.J. Ferna´ndez,
Eur. J. Inorg. Chem. (2000) 2055.
[12] (a) A. Ferna´ndez, P. Ur´ıa, J.J. Ferna´ndez, M. Lo´pez-Torres, A.
Sua´rez, D. Va´zquez-Garc´ıa, M.T. Pereira, J.M. Vila, J. Organo-
met. Chem. 620 (2001) 8;
Acknowledgements
(b) A. Ferna´ndez, D. Va´zquez-Garc´ıa, J.J. Ferna´ndez, M. Lo´pez-
Torres, A. Sua´rez, S. Castro-Juiz, J.M. Vila, New J. Chem. 26
(2002) 398;
We thank the DGES (Proyecto PB98-0638-C02-01/
02) and the Xunta de Galicia (Proyecto PGIDT99P-
XI20907B) for financial support.
(c) A. Amoedo, M. Grana, J. Mart´ınez, M.T. Pereira, M. Lo´pez-
˜
Torres, A. Ferna´ndez, J.J. Ferna´ndez, J.M. Vila, Eur. J. Inorg.
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[13] J.M. Vila, M. Gayoso, M.T. Pereira, M. Lo´pez, G. Alonso, J.J.
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