Synthesis, reactivity and characterization of cyclometallated palladium(II) compounds derived from pinacolone-N,N-dimethylhydrazone

Article abstract of DOI:10.1016/S0020-1693(02)01146-5

Pinacolone-N,N-dimethylhydrazone was regiospecifically cyclopalladated by Pd(OAc)₂ in glacial acetic acid on the -C(Me)=N-methyl group to give the acetato-bridged complex [Pd{CH₂C(CMe₃)=NNMe₂}(μ-O₂ CMe)]₂ (1). Subsequent treatment with aqueous sodium chloride or bromide gave the corresponding halide-bridged complexes [Pd{CH₂C(CMe₃)=NNMe₂}(μ-X)]₂ (2, X=Cl; 3, X=Br). Treatment of 2 and 3 with tertiary diphosphines in a 1:1 molar ratio yielded the dinuclear complexes [{Pd[CH₂C(CMe₃)=NNMe₂](X)}₂ {μ-Ph₂PRPPh₂}] (4, 5, R=CH₂; 6, 7, R=CHMe; 8, 9, R=CCH₂; 10, 11, R=NMe; 12, 13, R=trans-CHCH, 14, 15, R=C₂H₄, 16, 17, R=C₃H₆; 18, 19, R=C₄H₈). Treatment of 2 and 3 with AgClO₄ and the appropriate diphosphine ligand in a 1:2 molar ratio, afforded the mononuclear species [Pd{CH₂C(CMe₃)=NNMe₂}(Ph₂PRPPh ₂-P,P′)][ClO₄]}] (20, R=CH₂; 21, R=CHMe; 22, R=CCH₂; 23, R=NMe; 24, R=cis-CHCH, 25, R=C₂H₄, 26, R=C₃H₆; 27, R=C₄H₈). The complexes were characterized by elemental analysis (C, H, N), conductivity measurements, IR and ¹H and ³¹P{¹H} NMR spectroscopy, and by mass spectrometry.

Full text of DOI:10.1016/S0020-1693(02)01146-5

Inorganica Chimica Acta 342 (2003) 185ꢂ192
/
www.elsevier.com/locate/ica
Synthesis, reactivity and characterization of cyclometallated
palladium(II) compounds derived from
pinacolone-N,N-dimethylhydrazone
Jose´ M. Vila a,ꢀ, Margarita Lo´pez-Torres b, Alberto Ferna´ndez b, M. Teresa Pereira a,
Juna M. Ortigueira a, Jesu´s J. Ferna´ndez b
a
´ ´
Departamento de Quımica Inorganica, Universidad de Santiago de Compostela, E-15782 Santiago de Compostela, Spain
b
´
Departamento de Quımica Fundamental, Universidad de La Corun˜a, E-15071 La Corun˜a, Spain
Received 26 February 2002; accepted 31 May 2002
Abstract
Pinacolone-N,N-dimethylhydrazone was regiospecifically cyclopalladated by Pd(OAc)2 in glacial acetic acid on the Ã
methyl group to give the acetato-bridged complex [Pd{CH2C(CMe3)ÄNNMe2}(m-O2CMe)]2 (1). Subsequent treatment with
aqueous sodium chloride or bromide gave the corresponding halide-bridged complexes [Pd{CH2C(CMe3)ÄNNMe2}(m-X)]2 (2, Xꢁ
Cl; 3, XꢁBr). Treatment of 2 and 3 with tertiary diphosphines in a 1:1 molar ratio yielded the dinuclear complexes
[{Pd[CH2C(CMe3)ÄNNMe2](X)}2{m-Ph2PRPPh2}] (4, 5, RꢁCH2; 6, 7, RꢁCHMe; 8, 9, RꢁCCH2; 10, 11, RꢁNMe; 12, 13,
Rꢁtrans-CHCH, 14, 15, RꢁC2H4, 16, 17, RꢁC3H6; 18, 19, RꢁC4H8). Treatment of 2 and 3 with AgClO4 and the appropriate
diphosphine ligand in a 1:2 molar ratio, afforded the mononuclear species [Pd{CH2C(CMe3)ÄNNMe2}(Ph2PRPPh2-P,P?)][ClO4]}]
C2H4, 26, RꢁC3H6; 27, RꢁC4H8). The
/
C(Me)Ä/N-
/
/
/
/
/
/
/
/
/
/
/
/
/
/
(20, Rꢁ
/
CH2; 21, Rꢁ
/
CHMe; 22, Rꢁ
/
CCH2; 23, Rꢁ
/
NMe; 24, Rꢁ
/
cis-CHCH, 25, Rꢁ
/
/
/
complexes were characterized by elemental analysis (C, H, N), conductivity measurements, IR and 1H and 31P{1H} NMR
spectroscopy, and by mass spectrometry.
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Synthesis; Reactivity; Characterization
1. Introduction
cycles containing nitrogenꢂ
/
Pd and C(phenyl)Ã/Pd bonds
[7ꢂ9].
/
Cyclometallation reactions of aromatic substrates are
amongst the most thoroughly studied processes in
organometallic chemistry in view of their growing
chemistry and of the many applications they present.
To name a few, these compounds are successfully used
in organic synthesis [1,2] or in optical resolution [3,4],
and are rather promising as potential biologically active
materials [5] and liquid crystals [6]. Cyclometallated
compounds are usually classified according to the metal,
to the donor atom, or to chelate ring size; by far the
most well-studied examples are five-membered pallada-
Cyclometallation of a saturated aliphatic carbon
atom is generally more difficult to achieve than that of
an aromatic carbon (ortho-metallation), the latter being
more common [10], so less attention has been paid to the
preparation of complexes with C(sp3)Ã
/
Pd bonds in spite
of their broad synthetic potential [11], such as the
functionalization of unactivated methyl groups [12].
The first examples of saturated aliphatic carbons in
nitrogen donor ligands which have been cyclopalladated
were with 8-alkylquinolines [13,14].
We have been interested in cyclopalladated complexes
in which the metallated carbon atom, bearing sp2-
hybridization, is part of an aromatic ring belonging to
differently substituted Schiff base ligands derived from
mono- and diamines, [15,16] and dialdehydes, [17,18].
Our aim was to study the synthesis and reactivity of
ꢀ Corresponding author. Tel.: ꢃ
981-595 012
E-mail address: qideport@usc.es (J.M. Vila).
/34-981-563 100x14255; fax: ꢃ34-
/
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 1 4 6 - 5

186
J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ192
/
palladacycles prepared by activation of a non-aromatic
CÃH bond, for which purpose we chose ligands derived
from the condensation of a saturated aliphatic ketone,
tBuC(Ä
O)Me (pinacolone), and N,N-dimethylhydra-
zine, which are commonly used as a protecting group
for ketones. Although complexes 2 and 3 reported here
were known, we describe the preparation of the new
dinuclear species 1, and also a new approach to the
synthesis of compounds 2 and 3, via the dimer acetato-
bridged complex 1.
2.2.2. [Pd{CH2C(CMe3)Ä
/
NNMe2}(m-O2CMe)]2 (1)
/
MeC(CMe3)ÄNNMe2 (LH, 0.210 g, 1.476 mmol) and
/
palladium(II) acetate (0.300 g, 1.336 mmol) were added
to 40 cm3 of glacial acetic acid and refluxed under argon
for 4 h. After cooling the resulting suspension was
cooled, filtered through Celite to eliminate the small
amount of black palladium formed and the acetic acid
removed under vacuum. The residue was diluted with
water and extracted with dichloromethane. The com-
bined extracts were dried with anhydrous sodium
sulfate, filtered and then concentrated under reduced
pressure to give a yellow solid, which was chromato-
/
graphed on silica-gel. Elution with dichloromethaneꢂ
ethanol 1% gave the desired product, which was
obtained by removal of the solvent in vacuo and
/
2. Experimental
Safety note: 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.
recrystallization from dichloromethaneꢂn-hexane.
/
Yield: 75.4%. Anal. Found: C, 39.4; H, 6.2; N, 9.5.
Calc. for: C20H40N4O4Pd2, C, 39.1; H, 6.5; N, 9.1%. IR,
cmꢄ1: n(CÄ
/
N) 1642s; n(NÃ
/
N) 860sh, w; nas(COO)ꢁ
/
1
1409s. H NMR, d: 2.92 (s, NMe2),
1572s; ns(COO)ꢁ
/
t
2.17 (s, CH2), 2.16 (s, MeCO2), 1.11 (s, Bu).
2.1. General procedures
Alternatively, compound 1 could also be obtained by
treatment of the chloro-bridged cyclometallated com-
plex 2 (vide infra, 0.300 g, 0.529 mmol) and silver acetate
(0.097 g, 0.581 mmol) in acetone (20 cm3). The mixture
was refluxed for 5 h, cooled and filtered through Celite
to eliminate the silver chloride formed. The solvent was
removed in vacuo and the residue recrystallized in
All solvents were distilled prior to use from appro-
priate drying agents [19]. Ph2PC(Ä/CH2)PPh2 (vdpp) was
prepared according to procedures described elsewhere
[20]. All other chemicals were used as supplied from
commercial sources. NMR spectra were obtained as
CDCl3 solutions and referenced to SiMe4 (1H) or 85%
H3PO4 (31P{1H}), and were recorded on a Bruker AC
dichloromethaneꢂ
/
n-hexane to afford 1 (Yield: 81%).
1
200F spectrometer (200.0 MHz for H, 81.0 MHz for
31P{1H}). IR spectra were recorded as KBr pallets or
2.2.3. [Pd{CH2C(CMe3)Ä
/
NNMe2}(m-Cl)]2 (2)
Palladium(II) chloride (0.500 g, 2.819 mmol) and
lithium chloride (0.239 g, 5.637 mmol) were added in
methanol (20 cm3) and stirred for 1 h. A solution of
Nujol mulls on a PerkinꢂElmer 1330 spectrophot-
/
ometer. Mass spectra were obtained in a QUATRO
mass spectrometer with Cs ion-gun and 3-NBA matrix.
Conductivity measurements were made on a CRISON
GLP 32 conductivimeter using 10ꢄ3 M solutions in dry
acetonitrile at room temperature (r.t.) (298 K).
MeC(CMe3)Ä
/
NNMe2 (LH, 0.435 g, 3.058 mmol) in
ethanol (20 cm3) was added to the resulting suspension,
and the mixture stirred for 12 h, filtered, and the residue
washed with cold ethanol, dried in vacuo and recrystl-
lized from dichloromethaneꢂn-hexane. Yield: 88.4%.
/
Anal. Found: C, 34.3; H, 5.9; N, 10.0. Calc. for:
C16H34Cl2N4Pd2, C, 33.9; H, 6.0; N, 9.8%. IR, cmꢄ1
2.2. Syntheses
:
Cl) 300s, 253s. H
1
n(CÄ
/
N) 1638s; n(NÃ
/
N) 865w; n(PdÃ
/
t
2.2.1. MeC(CMe3)Ä
/
NNMe2, LH
NMR, d: 3.17 (s, CH2), 2.89 (s, NMe2), 1.13 (s, Bu).
Alternatively, compound 2 could also be obtained by
treatment of a solution of the acetate-bridged cyclome-
tallated complex 1 (0.200 g, 0.326 mmol) in acetone (25
cm3) with an aqueous solution of sodium chloride
(approximately 10ꢄ2 M). The mixture was stirred for
3 h and filtered off, the residue washed with water and
dried in vacuo. The resulting solid was chromato-
graphed on silica-gel, and the desired product eluted
with chloroform. Yield: 90.5%.
Pinacolone (methyl-terc-butylketone, 22 cm3, 0.207
mol) and N,N-dimethylhydrazine (26 cm3, 0.289 mol)
were refluxed for 24 h. The pale yellow solution was set
aside to r.t. and extracted with diethyl ether. The
combined organic extracts were dried with anhydrous
sodium carbonate, filtered and then concentrated under
vacuum. The residue was distilled under argon at r.t.,
and the fraction at 132ꢂ135 8C collected, yielding the
/
desired product as a colourless liquid. Yield: 80.0%.
Anal. Found: C, 67.0; H, 12.8; N, 20.1. Calc. for:
C8H18N2, C, 67.5; H, 12.7; N, 19.6%. IR, cmꢄ1: n(CÄ
/
N)
N) 828w. 1H NMR (d): 2.39 (s, NMe2), 1.91
2.2.4. [Pd{CH2C(CMe3)Ä
/
NNMe2}(m-Br)]2 (3)
To a solution of 2 (0.300 g, 0.529 mmol) in acetone
1640s; n(NÃ
/
(25 cm3) a large excess of lithium bromide was added.
t
(s, BuCMe), 1.09 (s, Bu).
t

J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ
/192
187
The mixture was stirred for 3 h, the solvent removed
under reduced pressure, and the residue triturated with
water to give a solid which was filtered, washed with
water and dried in vacuo. Recrystallization from
Cl]ꢃ, 788 [Mꢄ
/
Clꢄ
/
L]ꢃ, 753 [Mꢄ
/
2Clꢄ
/
L]ꢃ, 645
[LPd(PP)]ꢃ, 504 [Pd(PP)]ꢃ.
2.2.8. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Br)}2{m-
dichloromethaneꢂ
Yield: ꢀ95%. Anal. Found: C, 29.5; H, 5.2; N, 8.6.
Calc. for C16H34Br2N4Pd2: C, 29.3; H, 5.2; N, 8.5%. IR,
/n-hexane gave the desired product.
Ph2PCH(Me)PPh2}] (7)
Yield: 77.5%. Anal. Found: C, 48.1; H, 5.7; N, 5.4.
Calc. for C42H58N4Br2P2Pd2: C, 47.8; H, 5.5; N, 5.3%.
/
1
cmꢄ1: n(CÄ
/
N) 1638s; n(NÃ
/
N) 855w. H NMR, d: 3.22
IR, cmꢄ1: n(CÄ
d: 4.64 (m, CHMe), 2.97 (b, NMe2), 2.91 (b, NMe2),
/
N) 1635m; n(NÃ
/
N) 852sh,m. 1H NMR,
t
(s, CH2), 2.95 (s, NMe2), 1.14 (s, Bu).
Alternatively, compound 3 could also be obtained by
treatment of a solution of the acetate-bridged cyclome-
tallated complex 1 (0.200 g, 0.326 mmol) in acetone (25
cm3) with an aqueous solution of sodium bromide
(approximately 10ꢄ2 M). The mixture was stirred for
3 h and filtered off, the residue washed with water and
dried in vacuo. The resulting solid was chromato-
graphed on silica-gel, eluting the desired product with
chloroform. Yield: 85.9%.
2.26 (m, CH2), 1.66 (m, CHMe), 0.89 (s, Bu). 31P{1H}
t
NMR, d: 35.33 (s). m/z (FAB): 973 [Mꢄ
[MꢄBrꢄ 2Brꢄ
L]ꢃ, 753 [Mꢄ L]ꢃ, 645 [LPd(PP)]ꢃ,
504 [Pd(PP)]ꢃ.
/
Br]ꢃ, 832
/
/
/
/
2.2.9. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Cl)}2{m-
Ph2PC(Ä
/
CH2)PPh2}] (8)
Yield: 70.9%. Anal. Found: C, 52.5; H, 5.9; N, 6.0.
Calc. for C42H56N4Cl2P2Pd2: C, 52.4; H, 5.8; N, 5.8. IR,
cmꢄ1: n(CÄ
/
N) 1634m; n(NÃ
1H NMR, d: 6.92 (m, CÄ
CH2), 2.63 (b, NMe2), 2.16 (b,
CH2), 0.90 (s, Bu). 31P{1H} NMR, d: 36.23 (s). m/z
(FAB): 927 [Mꢄ Clꢄ
Cl]ꢃ, 786 [Mꢄ L]ꢃ, 751 [Mꢄ
2Clꢄ
L]ꢃ, 643 [LPd(PP)]ꢃ, 502 [Pd(PP)]ꢃ.
/
N) 859m; n(PdÃ
/
Cl) 280m.
2.2.5. [{Pd[CH2C(CMe3)Ä
/NNMe2](Cl)}2(m-
/
Ph2PCH2PPh2)] (4)
t
To a solution of 2 (50 mg, 0.088 mmol) in dichlor-
omethane (approximately 15 cm3), dppm (34 mg, 0.088
mmol) was added. The mixture was stirred for 1 h, after
which the solvent was removed under reduced pressure
/
/
/
/
/
and the residue recrystallized from dichloromethaneꢂn-
hexane. Yield: 67.5%. Anal. Found: C, 52.0; H, 6.0; N,
5.9. Calc. for C41H56N4Cl2P2Pd2: C, 51.8; H, 5.9; N,
/
2.2.10. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Br)}2{m-
Ph2PC(Ä
/
CH2)PPh2}] (9)
Yield: 58.0%. Anal. Found: C, 48.3; H, 5.0; N, 5.6.
Calc. for C42H56N4Br2P2Pd2: C, 47.9; H, 5.3; N, 5.3%.
5.8%. IR, cmꢄ1: n(CÄ
/
N) 1637m; n(NÃ
/
N) 858sh,w;
1
2
Cl) 285m. H NMR, d: 4.24 (t, PCH2P, J(PH)
IR, cmꢄ1: n(CÄ
/
N) 1638m; n(NÃ
CH2), 2.67 (b, NMe2), 2.31 (b, CH2), 0.93
(s, Bu). 31P{1H} NMR, d: 35.84 (s). m/z (FAB): 971
[Mꢄ Brꢄ 2Brꢄ
Br]ꢃ, 830 [Mꢄ L]ꢃ, 751 [Mꢄ L]ꢃ, 643
[LPd(PP)]ꢃ, 502 [Pd(PP)]ꢃ.
/
N) 862sh,w. 1H NMR,
n(PdÃ
/
11.2), 2.84 (b, NMe2), 2.10 (d, CH2, 2J(PCH2) 3.3), 0.93
d: 6.93 (m, CÄ
/
t
(s, Bu). 31P{1H} NMR, d: 24.31 (s). m/z (FAB): 915
t
[Mꢄ
[LPd(PP)]ꢃ, 490 [Pd(PP)]ꢃ.
Compounds 5ꢂ19 were prepared similarly, but using
/
Cl]ꢃ, 774 [Mꢄ
/
Clꢄ
/
L]ꢃ, 739 [Mꢄ
/
2Clꢄ
L]ꢃ, 631
/
/
/
/
/
/
/
the corresponding halide-bridged and diphosphine as
appropiate.
2.2.11. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Cl)}2{m-
Ph2PN(Me)PPh2}] (10)
Yield: 89.3%. Anal. Found: C, 51.3; H, 6.1; N, 7.6.
Calc. for C41H57N5Cl2P2Pd2: C, 51.0; H, 5.9; N, 7.2%.
2.2.6. [{Pd[CH2C(CMe3)Ä/NNMe2](Br)}2(m-
Ph2PCH2PPh2)] (5)
Yield: 69.4%. Anal. Found: C, 45.9; H, 5.6; N, 5.5.
IR, cmꢄ1: n(CÄ
277m. H NMR, d: 2.86 (b, NMe2), 2.68 (t, PNMeP,
/
N) 1633m; n(NÃ
/
N) 853sh,w; n(PdÃ
/Cl)
1
Calc. for C41H56N4Br2P2Pd2: C, 46.4; H, 5.3; N, 5.2%.
IR, cmꢄ1: n(CÄ
3J(PH) 11.1), 2.40 (b, CH2), 0.90 (s, Bu). 31P{1H}
t
/
N) 1636m; n(NÃ
/
N) 858sh,w. 1H NMR,
NMR, d: 82.14 (s). m/z (FAB): 930 [Mꢄ
[MꢄClꢄ 2Clꢄ
L]ꢃ, 754 [Mꢄ L]ꢃ, 646 [LPd(PP)]ꢃ, 505
[Pd(PP)]ꢃ.
/
Cl]ꢃ, 789
d: 4.35 (t, PCH2P, 2J(PH) 11.5), 2.89 (s, NMe2), 2.20 (d,
/
/
/
/
CH2, J(PCH2) 3.2), 0.92 (s, Bu). 31P{1H} NMR, d:
24.47 (s). m/z (FAB): 959 [Mꢄ Brꢄ
Br]ꢃ, 818 [Mꢄ L]ꢃ,
739 [Mꢄ2Brꢄ
L]ꢃ, 631 [LPd(PP)]ꢃ, 490 [Pd(PP)]ꢃ.
2
t
/
/
/
/
/
2.2.12. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Br)}2{m-
2.2.7. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Cl)}2{m-
Ph2PN(Me)PPh2}] (11)
Yield: 84.2%. Anal. Found: C, 47.0; H, 5.5; N, 6.9.
Calc. for C41H57N5Br2P2Pd2: C, 46.7; H, 5.4; N, 6.6%.
Ph2PCH(Me)PPh2}] (6)
Yield: 85.7%. Anal. Found: C, 52.4; H, 6.4; N, 6.0.
Calc. for C42H58N4Cl2P2Pd2: C, 52.2; H, 6.0; N, 5.8%.
IR, cmꢄ1: n(CÄ
IR, cmꢄ1: n(CÄ
2.83 (s, NMe2), 2.51 (t, PNMeP, J(PH) 9.3), 2.38 (b,
/
N) 1636m; n(NÃ
/
N) 860w. 1H NMR, d:
3
/
N) 1638m; n(NÃ
/
N) 860sh,w; n(PdÃ
/
Cl)
1
t
285m. H NMR, d: 4.64 (m, CHMe), 2.90 (b, NMe2),
2.88 (b, NMe2), 2.10 (m, CH2), 1.74 (m, CHMe), 0.89 (s,
CH2), 0.86 (s, Bu). 31P{1H} NMR, d: 83.30 (s). m/z
(FAB): 974 [Mꢄ
/
Br]ꢃ, 832 [Mꢄ
/
Brꢄ
/
L]ꢃ, 754 [Mꢄ
/
tBu). 31P{1H} NMR, d: 35.06 (s). m/z (FAB): 929 [Mꢄ
/
2Brꢄ
/
L]ꢃ, 646 [LPd(PP)]ꢃ, 505 [Pd(PP)]ꢃ.

188
J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ192
/
2.2.13. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Cl)}2{m-
d: 2.93 (s, NMe2), 2.18 (d, CH2, 2J(PCH2) 3.2), 0.91 (s,
tBu). 31P{1H} NMR, d: 27.97 (s). m/z (FAB): 987 [Mꢄ
Br]ꢃ, 927 [MꢄL]ꢃ, 846 [Mꢄ L]ꢃ, 659
Brꢄ
[LPd(PP)]ꢃ, 518 [Pd(PP)]ꢃ.
trans(Ph2PCHÄ
/
CHPPh2)}] (12)
/
Yield: 59.5%. Anal. Found: C, 52.6; H, 6.0; N, 6.1.
/
/
/
Calc. for C42H56N4Cl2P2Pd2: C, 52.4; H, 5.8; N, 5.8%.
IR, cmꢄ1: n(CÄ
/
N) 1639m; n(NÃ
283m. 1H NMR, d: 7.19 (at, HCÄ
CH, N 38.2), 2.96 (b,
NMe2), 2.25 (b, CH2), 0.96 (s, Bu). 31P{1H} NMR, d:
26.17 (s). m/z (FAB): 927 [Mꢄ
Cl]ꢃ, 821 [MꢄL]ꢃ, 785
[MꢄClꢄ
L]ꢃ, 643 [LPd(PP)]ꢃ, 502 [Pd(PP)]ꢃ.
/
N) 860w; n(PdÃ
/
Cl)
/
2.2.19. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Cl)}2{m-
t
Ph2P(CH2)4PPh2}] (18)
Yield: 93.0%. Anal. Found: C, 53.3; H, 6.3; N, 5.5.
/
/
/
/
Calc. for C44H62N4Cl2P2Pd2: C, 53.2; H, 6.2; N, 5.6%.
IR, cmꢄ1: n(CÄ
/
N) 1637m; n(NÃ
/
N) 857sh,m; n(PdÃ
/
Cl)
281m. 1H NMR, d: 2.92 (s, NMe2), 2.91 (s, NMe2), 2.09
(d, CH2, 2J(PCH2) 3.6), 0.91 (s, tBu). 31P{1H} NMR, d:
2.2.14. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Br)}2{m-trans-
(Ph2PCHÄ
/
CHPPh2)}] (13)
Yield: 75.9%. Anal. Found: C, 50.0; H, 5.5; N, 5.5.
Calc. for C42H56N4Br2P2Pd2: C, 47.9; H, 5.3; N, 5.3%.
27.54 (s). m/z (FAB): 957 [Mꢄ
/
Cl]ꢃ, 851 [MꢄL]ꢃ, 816
/
[MꢄClꢄ
/
/
L]ꢃ, 673 [LPd(PP)]ꢃ, 531 [Pd(PP)]ꢃ.
IR, cmꢄ1: n(CÄ
/
N) 1641m; n(NÃ
/
N) 861sh,w. 1H NMR,
d: 7.32 (at, HCÄCH, N 38.8), 3.02 (b, NMe2), 2.33 (b,
/
2.2.20. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Br)}2{m-
t
CH2), 0.94 (s, Bu). 31P{1H} NMR, d: 26.92 (s). m/z
(FAB): 971 [Mꢄ Brꢄ
Br]ꢃ, 908 [MꢄL]ꢃ, 830 [Mꢄ
L]ꢃ, 751 [Mꢄ L]ꢃ, 643 [LPd(PP)]ꢃ, 502
2Brꢄ
[Pd(PP)]ꢃ.
Ph2P(CH2)4PPh2}] (19)
Yield: 88.8%. Anal. Found: C, 48.8; H, 5.9; N, 4.9.
/
/
/
/
/
/
Calc. for C44H62N4Br2P2Pd2: C, 48.8; H, 5.7; N, 5.1%.
IR, cmꢄ1: n(CÄ
/
N) 1641m; n(NÃ
/
N) 858w. 1H NMR, d:
2.98 (s, NMe2), 2.97 (s, NMe2), 2.20 (d, CH2, 2J(PCH2)
3.3), 0.92 (s, Bu). 31P{1H} NMR, d: 28.25 (s). m/z
t
2.2.15. [{Pd[CH2C(CMe3)Ä
/
NNMe2](Cl)}2{m-
Ph2P(CH2)2PPh2}] (14)
Yield: 81.0%. Anal. Found: C, 52.4; H, 6.2; N, 6.0.
(FAB): 987 [Mꢄ
/
Br]ꢃ, 927 [Mꢄ
/
L]ꢃ, 860 [Mꢄ
/
Brꢄ
/
L]ꢃ, 673[LPd(PP)]ꢃ, 531 [Pd(PP)]ꢃ.
Calc. for C42H58N4Cl2P2Pd2: C, 52.5; H, 6.0; N, 5.8%.
Cl)
IR, cmꢄ1: n(CÄ
290m. H NMR, d: 2.93 (b, NMe2), 2.10 (b, CH2), 0.91
/
N) 1637m; n(NÃ
/
N) 861sh,w; n(PdÃ
/
2.2.21. [Pd{CH2C(CMe3)Ä
/
NNMe2}(Ph2PCH2PPh2-
1
P,P?)][ClO4] (20)
t
(s, Bu). 31P{1H} NMR, d: 29.66 (s). m/z (FAB): 929
To a solution of 2 (40 mg, 0.070 mmol) in acetonitrile
(approximately 15 cm3), silver perchlorate (29 mg, 0.140
mmol) was added. The mixture was stirred for 1 h and
filtered through Celite to eliminate the silver chloride
precipitate, and the solvent removed under reduced
pressure. The residue was dissolved in ethanol (15
cm3), dppm (54 mg, 0.140 mmol) was added and the
mixture stirred for 12 h. The precipitate formed was
filtered off, yielding a solid which was recrystallized
[Mꢄ
/
Cl]ꢃ, 822 [Mꢄ
/
L]ꢃ, 788 [Mꢄ
/
Clꢄ
L]ꢃ, 645
/
[LPd(PP)]ꢃ, 504 [Pd(PP)]ꢃ.
2.2.16. [{Pd[CH2C(CMe3)Ä/NNMe2](Br)}2{m-
Ph2P(CH2)2PPh2}] (15)
Yield: 89.5%. Anal. Found: C, 48.0; H, 5.1; N, 5.6.
Calc. for C42H58N4Br2P2Pd2: C, 47.8; H, 5.5; N, 5.3%.
IR, cmꢄ1: n(CÄ
/
N) 1640m; n(NÃ
d: 2.98 (s, NMe2), 2.17 (d, CH2, 2J(PCH2) 3.5), 0.91 (s,
tBu). 31P{1H} NMR, d: 30.06 (s). m/z (FAB): 972 [Mꢄ
Br]ꢃ, 910 [MꢄL]ꢃ, 829 [Mꢄ L]ꢃ, 645
Clꢄ
[LPd(PP)]ꢃ, 504 [Pd(PP)]ꢃ.
/
N) 860sh,w. 1H NMR,
from dichloromethaneꢂn-hexane. Yield: 53.4%.
/
/
Anal. Found: C, 53.9; H, 5.6; N, 3.9. Calc. for
/
/
/
C33H39N2ClO4P2Pd: C, 54.1; H, 5.3; N, 3.8%. IR,
1
N) 856sh,w. H NMR, d:
cmꢄ1: n(CÄ
/
N) 1636m; n(NÃ
/
4.30 (dd, PCH2P, 2J(Ptrans-NH) 11.4, 2J(Ptrans-CH) 8.3),
3.11 (dd, CH2, 2J(PCH2) 7.5, 2.7), 2.55 (b, NMe2), 1.11
2.2.17. [{Pd[CH2C(CMe3)Ä/NNMe2](Cl)}2{m-
t
2
Ph2P(CH2)3PPh2}] (16)
Yield: 85.9%. Anal. Found: C, 52.8; H, 5.9; N, 5.6.
(s, Bu). 31P{1H} NMR, d: ꢄ
53.4), ꢄ
[Pd(PP)]ꢃ.
Compounds 21ꢂ
the corresponding diphosphine as appropriate.
/
5.23 (d, Ptrans-N, J(PP)
/
26.75 (d, Ptrans-C). m/z (FAB): 631 [M]ꢃ, 490
Calc. for C43H60N4Cl2P2Pd2: C, 52.7; H, 6.1; N, 5.3%.
IR, cmꢄ1: n(CÄ
/
N) 1636m; n(NÃ
/
N) 857sh,w; n(PdÃ
/
Cl)
290m. 1H NMR, d: 2.89 (s, NMe2), 2.88 (s, NMe2), 2.10
(d, CH2, 2J(PCH2) 3.4), 0.92 (s, tBu). 31P{1H} NMR, d:
/27 were prepared similarly, but using
27.06 (s). m/z (FAB): 943 [Mꢄ
/
Cl]ꢃ, 837 [Mꢄ
/
L]ꢃ, 802
2.2.22. [Pd{CH2C(CMe3)Ä
/
[MꢄClꢄ
/
/
L]ꢃ, 659 [LPd(PP)]ꢃ, 518 [Pd(PP)]ꢃ.
NNMe2}{Ph2PCH(Me)PPh2-P,P?}][ClO4] (21)
Yield: 94.5%. Anal. Found: C, 53.5; H, 5.3; N, 6.0.
Calc. for C34H41N2ClO4P2Pd: C, 53.0; H, 5.4; N, 5.6%.
2.2.18. [{Pd[CH2C(CMe3)Ä/NNMe2](Br)}2{m-
Ph2P(CH2)3PPh2}] (17)
Yield: 84.4%. Anal. Found: C, 48.4; H, 5.6; N, 5.6.
IR, cmꢄ1: n(CÄ
/
N) 1638m; n(NÃ
/
N) 858w. 1H NMR, d:
2.91 (dd, CH2, 2J(Ptrans-NH) 7.3, 2J(Ptrans-CH) 3.0), 2.85
3
(b, NMe2), 2.51 (dd, PNMeP, J(PH) 9.8, 8.8), 1.10 (s,
tBu). 31P{1H} NMR, d: 8.82 (d, Ptrans-N, J(PP) 26.7),
Calc. for C43H60N4Br2P2Pd2: C, 48.3; H, 5.6; N, 5.2%.
N) 858sh,w. 1H NMR,
IR, cmꢄ1: n(CÄ
/
N) 1638m; n(NÃ
/
2

J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ
/192
189
ꢄ
/
10.25 (d, Ptrans-C). m/z (FAB): 645 [M]ꢃ, 504
[Pd(PP)]ꢃ.
2.2.28. [Pd{CH2C(CMe3)Ä
/
NNMe2}{Ph2P(CH2)4PPh2)-P,P?}][ClO4] (27)
Yield: 89.9%. Anal. Found: C, 56.0; H, 5.7; N, 3.5.
Calc. for C36H45N2ClO4P2Pd: C, 55.8; H, 5.8; N, 3.6%.
N) 859w. 1H NMR, d:
IR, cmꢄ1: n(CÄ
2.59 (dd, CH2, J(Ptrans-NH) 10.9, J(Ptrans-CH) 5.4),
/
N) 1639m; n(NÃ
/
2.2.23. [Pd{CH2C(CMe3)Ä
/
NNMe2}{Ph2PC(Ä
/
2
2
CH2)PPh2-P,P?}][ClO4] (22)
Yield: 59.9%. Anal. Found: C, 54.8; H, 5.0; N, 3.5.
2.29(b, NMe2), 0.90 (s, tBu). 31P{1H} NMR, d: 28.02 (d,
2
trans-N, J(PP) 35.0), 11.51 (d, Ptrans-C). m/z (FAB):
Calc. for C34H39N2ClO4P2Pd: C, 54.9; H, 5.2; N, 3.7%.
IR, cmꢄ1: n(CÄ
P
/
N) 1635m; n(NÃ
/
N) 858w. 1H NMR, d:
673 [M]ꢃ, 532 [Pd(PP)]ꢃ.
6.23 (m, CÄ
/
CH2), 3.11 (dd, CH2, 2J(Ptrans-NH) 7.5,
2J(Ptrans-CH) 3.0), 2.96 (s, NMe2), 1.15 (s, tBu). 31P{1H}
2
NMR, d: 25.38 (d, Ptrans-N, J(PP) 19.0), ꢄ
/
3.74 (d,
3. Results and discussion
P
trans-C). m/z (FAB): 643 [M]ꢃ, 502 [Pd(PP)]ꢃ.
For the convenience of the reader the compounds and
reactions are shown in Schemes 1 and 2.
The ligand was synthesized by condensation of
pinacolone and N,N-dimethylhydrazine as a colourless
liquid. Shaw et al. [21,22] reported that treatment of the
2.2.24. [Pd{CH2C(CMe3)Ä
/
NNMe2}{Ph2PN(Me)PPh2-P,P?}][ClO4] (23)
Yield: 62.5%. Anal. Found: C, 54.3; H, 5.4; N, 3.8.
Calc. for C33H40N3ClO4P2Pd: C, 54.4; H, 5.2; N, 3.7%.
IR, cmꢄ1: n(CÄ
/
N) 1637m; n(NÃ
/
N) 859w. 1H NMR, d:
dimethylhydrazone of pinacolone with Na2PdCl4ꢂ
NaOAc promotes regiospecific palladation on theÃ
N-methyl group and coordination of the di-
/
2.98 (dd, CH2, 2J(Ptrans-NH) 6.6, 2J(Ptrans-CH) 3.6), 2.67
/
(b, NMe2), 1.09 (s, Bu). 31P{1H} NMR, d: 57.10 (d,
t
C(Me)Ä
/
2
trans-N, J(PP) 50.9), 45.69 (d, Ptrans-C). m/z (FAB):
methylamine group to the metal atom in 83% yield. In
contrast with this, dimethylhydrazones of mixed
P
646 [M]ꢃ, 505 [Pd(PP)]ꢃ.
aliphaticꢂ
ortho-palladation and the Ã
/
aromatic ketones preferentially undergo
CÄN nitrogen atom coordi-
/
/
nates to palladium. More recently [PdCl2(PPh3)2] has
been proved to be an efficient reagent in the metallation
reaction of tertiary carbon atoms [23,24]. Nevertheless,
the most used palladium(II) salt in cyclometallation
reactions, Pd(OAc)2, has been scarcely chosen as a
starting material in similar processes, and only reaction
with N,N-dimethylneopentylamine has been reported,
yielding a novel trinuclear complex [25]. The need of
compounds 2 and 3 as starting matetials led us to revisit
the synthetic methods previously employed.
2.2.25. [Pd{CH2C(CMe3)Ä
/
NNMe2}{cis-(Ph2PCHÄ
/
CHPPh2)-P,P?}][ClO4] (24)
Yield: 75.9%. Anal. Found: C, 55.0; H, 5.6; N, 3.9.
Calc. for C34H39N2ClO4P2Pd: C, 54.7; H, 5.5; N, 3.7%.
IR, cmꢄ1: n(CÄ
/
N) 1636m; n(NÃ
/
N) 854w. 1H NMR, d:
5.00 (m, CHMe), 3.29 (m, CH2), 2.66(b, NMe2), 1.15 (s,
tBu). 31P{1H} NMR, d: 63.37 (d, Ptrans-N, 2J(PP) 59.7),
53.17 (d,
[Pd(PP)]ꢃ.
P
trans-C). m/z (FAB): 643 [M]ꢃ, 502
Thus, treatment of LH with Pd(OAc)2 in glacial acetic
acid, under argon at 100 8C, gave the new dinuclear
acetato-bridged ortho-palladated complex [Pd{CH2C-
2.2.26. [Pd{CH2C(CMe3)Ä
/
NNMe2}{Ph2P(CH2)2PPh2)-P,P?}][ClO4] (25)
Yield: 58.4%. Anal. Found: C, 55.0; H, 5.6; N, 3.6.
Calc. for C34H41N2ClO4P2Pd: C, 54.7; H, 5.5; N, 3.7%.
IR, cmꢄ1: n(CÄ
/
N) 1639m; n(NÃ
/
N) 857w. 1H NMR, d:
2.74 (dd, CH2, 2J(Ptrans-NH) 6.6, 2J(Ptrans-CH)3.6), 2.60
(s, NMe2), 2.59 (s, NMe2), 1.05 (s, tBu). 31P{1H} NMR,
d: 53.09 (d, Ptrans-N, 2J(PP) 53.0), 36.44 (d, Ptrans-C). m/
z (FAB): 645 [M]ꢃ, 504 [Pd(PP)]ꢃ.
2.2.27. [Pd{CH2C(CMe3)Ä
/
NNMe2}{Ph2P(CH2)3PPh2)-P,P?}][ClO4] (26)
Yield: 74.6%. Anal. Found: C, 55.6; H, 5.9; N, 3.8.
Calc. for C35H43N2ClO4P2Pd: C, 55.3; H, 5.7; N, 3.6%.
IR, cmꢄ1: n(CÄ
/
N) 1635m; n(NÃ
/
N) 856w. 1H NMR, d:
2.45 (dd, CH2, 2J(Ptrans-NH) 6.4, 2J(Ptrans-CH) 5.0), 2.38
(s, NMe2), 2.37 (s, NMe2), 0.93 (s, tBu). 31P{1H} NMR,
2
d: 16.49 (d, Ptrans-N, J(PP) 53.4), ꢄ
/4.48 (d, Ptrans-C).
m/z (FAB): 659 [M]ꢃ, 518 [Pd(PP)]ꢃ.
Scheme 1.

190
J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ192
/
Scheme 2.
(CMe3)Ä
/
NNMe2}(m-O2CMe)]2 (1), in 75.4% yield. The
N) and n(NÃN)
was shifted to higher frequency with respect to the free
ligand consequent upon coordination of the amine
nitrogen atom to palladium [29].
Treatment of 1 with the appropriate aqueous sodium
halide, in a typical metathesis reaction, gave the halide-
IR spectrum of 1 showed the n(CÄ
/
/
stretches at 1642 and 860 cmꢄ1, respectively, which were
shifted to higher wavenumbers, as compared with the
free ligand, due to N-coordination of the amine. The IR
spectrum also showed two strong bands at 1572 and
1409 cmꢄ1 assigned to the nas(COO) and ns(COO)
stretching vibrations of the acetate ligand, respectively,
[26]. In the 1H NMR spectrum, the methyl groups of the
acetate ligands gave rise to only one singlet at d 2.16,
indicating that they were equivalent, which was in
agreement with a trans-geometry of the cyclometallated
moieties in the anti-isomer [27,28]. A singlet integrating
bridged complexes [Pd{CH2C(CMe3)Ä
/
NNMe2}(m-X)]2×
/
(2, XꢁCl; 3, XꢁBr) (see Section 2). Compound 2
/
/
could also be synthesized via reaction of L with lithium
tetrachloropalladate in 88.4% yield, as previously re-
ported [21,22]. The IR spectrum of 2 showed two n(PdÃ
/
Cl) bands at 300 and 253 cmꢄ1, consistent with an
asymmetric Pd2Cl2 bridging unit [30]. The 1H NMR
spectra of compounds 2 and 3 showed the CH2
resonance shifted to higher frequency, in comparison
with the spectrum for compound 1, due to the planar
arrangement of 2 and 3, as opposed to the ‘open-book’
geometry of 1, in agreement with structural data
reported earlier [31,32]. Compound 2 provided an
alternative route to 1. Thus, treatment of 2 with silver
acetate in acetone gave 1 in good yield (see Section 2),
avoiding the use of acidic media (vide supra).
for two proton atoms at d 2.17 was assigned to the Ã
C(CH2)ÄN-methylene group, indicating that CÃH me-
tallation occurred at the NÄC(Me) methyl group. The
/
/
/
/
shift towards lower frequency of this signal, in compar-
ison with the halide-bridged complexes (see Section 2),
was due to the shielding effect produced by the ‘open-
book’ configuration of the complex in which the
cyclometallated ligands are nearly face-to-face, similar
to that observed in the related dinuclear species [16]. The
signals at d 2.92 and 1.11 were assigned to the NMe2
and CMe3 proton resonances, respectively, the former
Reaction of 2 or 3, in dichloromethane at room
temperature, with tertiary diphosphines in a 1:1 molar
ratio gave the dinuclear cyclometallated complexes

J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ
/192
191
[{Pd[CH2C(CMe3)Ä
X: CH2, Cl 4; CH2, Br 5; CHMe, Cl 6; CHMe, Br 7;
CÄCH2, Cl 8; CÄCH2, Br 9; NMe, Cl 10; NMe, Br 11;
trans-CHÄCH, Cl 12; trans-CHÄCH, Br 13; (CH2)2, Cl
/
NNMe2](X)}2(m-Ph2PRPPh2)] (R,
The larger ‘bite’ diphosphine precludes any possibility of
a bridging halogen ligand between the two palladium
atoms. Consequently, the corresponding conductivity
data are in accordance with a neutral formulae for these
compounds.
Treatment of 2 or 3 with silver perchlorate in 1:2
molar ratio in acetonitrile at room temperature, fol-
lowed by reaction with tertiary diphosphines in ethanol,
yielded the mononuclear cyclometallated compounds
/
/
/
/
14; (CH2)2, Br 15; (CH2)3, Cl 16; (CH2)3, Br 17; (CH2)4,
Cl 18; (CH2)4, Br 19) (see Scheme 2). The new
compounds were air-stable and soluble in the more
common organic solvents, such as toluene, chloroform,
acetone or ethanol. They were characterized by elemen-
1
tal analysis, infrared spectra, mass spectrometry and H
[Pd{CH2C(CMe3)ÄNNMe2}(Ph2PRPPh2-P,P?)][ClO4]
/
and 31P{1H} NMR in CDCl3 (data in Section 2). The 1H
NMR spectra showed the CH2 proton signals shifted to
lower frequency by approximately 1 ppm with respect to
their position in the starting material, due to the
shielding effect of the phosphine phenyl rings. This
resonance appeared as a multiplet or as a broad signal,
but in some compounds it could be clearly distinguished
as a doublet by coupling to the phosphorus nucleus
(R: CH2, 20; CHMe, 21; CÄ
/
CH2, 22; NMe, 23; cis-CHÄ
/
CH, 24; (CH2)2, 25; (CH2)3, 26; (CH2)4, 27) (see Scheme
2) as air-stable solids which were fully characterized (see
Section 2). The PdÃ
/
X bonds were absent and the
diphosphine was chelated to the metal center through
the two phosphorus atoms. The 1H NMR spectra
showed the CH2 resonance as a doublet of doublets by
coupling to both 31P nuclei [2J(Ptrans-CH)ꢀ2
/
J(Ptrans-
NH)], and shifted to lower field as compared with
compounds 4ꢂ19 due to the effect of the PPh2 groups
[2J(PCH2)ꢁ
/
3.2ꢂ3.5 Hz], suggesting a cis-geometry of
/
the phosphine and of the metallated methylene group.
The NMe2 resonance appeared approximately d 2.8, a
position similar to that observed in the spectra of
complexes 2 and 3. The 1H NMR spectra of compounds
4 and 5 showed the PCH2P resonance as a triplet by
coupling to the 2 equiv. phosphorus atoms and no
geminal coupling was observed. The 1H NMR spectra of
compounds 12 and 13 showed the proton part of the
/
cis to the metallated carbon atom. The NMe2 resonance
was shifted to higher field due to the shielding effect of
the PPh2 group trans to carbon, and appeared as two
singlets. We suggest this is due to the different space
configuration of the phenyl rings on the phosphorus
atom trans to nitrogen. This was most noteciable in
compounds 26 and 27, due to larger chelate ring size.
The 31P{1H} NMR spectra showed two doublets,
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 [33]. This was confirmed
by selective decoupling experiments. The 31P chemical
shifts are clearly influenced by ring size, [38] and the
AA?XX? spin system due to the PCH Ä/CHP resonances
as an apparent triplet approximately d 7.20. The
31P{1H} NMR spectra displayed a singlet in all cases,
shifted to higher frequency from the free phosphine, in
agreement with phosphorus coordination to metal
center [33]. These data confirmed that the phosphorus
atom was trans to the nitrogen atom, and that the two
phosphorus nuclei were equivalent with the diphosphine
acting as a bridging ligand. For complexes with chloro
ligands the IR spectra showed a band approximately 275
corresponding data for compounds 20ꢂ
ized in Table 1. The four-membered ring compounds
20ꢂ22 gave a negative DR, as well as the larger ring
/27 are summar-
cmꢄ1 assigned to the n(PdÃ
For complexes 4ꢂ
among others, fragment ions assigned to [Mꢄ
[MꢄXꢄ [Mꢄ2Xꢄ
L]ꢃ, L]ꢃ, [LPd(PP)]ꢃ
/
Cl) stretching vibration.
/
/
11 the MS FAB spectra showed,
compounds 26 and 27. In the case of compound 23, the
effect of the heteroatom in the phosphine backbone gave
a positive DR, similar to the values of the five-membered
/
X]ꢃ,
and
/
/
/
/
[Pd(PP)]ꢃ, which were characteristic clusters of isotopic
peaks covering approximately 10 m/z units, due to the
presence of the numerous palladium isotopes [34,35],
thereby confirming the dinuclear nature of these com-
plexes (see Section 2). The values of conductivity data
were intermediate between those observed for neutral
compounds and for 1:1 electrolytes (Scheme 2) [36]. We
have previously reported that similar complexes derived
from benzylidenimines show an interconversion between
two conformations in solution that lead either to
electrolyte species or to molecular compounds [37].
Table 1
31P parameters
a
d (Ptrans -N
)
DR
20
21
22
23
24
25
26
27
ꢄ5.23
8.82
ꢄ39.08
ꢄ25.03
ꢄ8.47
ꢃ23.25
ꢃ29.32
ꢃ19.24
ꢄ17.36
ꢄ5.82
25.38
57.10
63.37
53.09
16.49
28.02
For complexes 12ꢂ
slightly different fragmentation pattern, with the pre-
sence of peaks assigned to the [Mꢄ
X]ꢃ, [MꢄL]ꢃ,
[MꢄXꢄ
L]ꢃ, [LPd(PP)]ꢃ and [Pd(PP)]ꢃ fragments.
/
19 the MS FAB spectra showed a
a
Difference respect to an equivalent phosphorus in a non-chelated
analogue, [LPd(PPh3)(Cl)] (PPh3 trans to nitrogen, d 33.85 ppm),
reference [22].
/
/
/
/

192
J.M. Vila et al. / Inorganica Chimica Acta 342 (2003) 185ꢂ192
/
[18] M. Lo´pez-Torres, A. Ferna´ndez, J.J. Ferna´ndez, A. Sua´rez, M.T.
Pereira, S. Castro-Juiz, J.M. Vila, Organometallics 20 (2001)
1350.
ring compounds. The MS FAB spectra show similar
fragmentation patterns, containing two intense peaks
assigned to [Mꢃ] and [Mꢃꢄ
PP] ions (see data in
/
[19] W.L.F. Armarego, D.D. Perrin, Purification of Laboratory
Chemicals, fourth ed., Butterworth-Heinemann, Oxford, 1997.
[20] I.J. Colquhoun, W. McFarlane, J. Chem. Soc., Dalton Trans.
(1982) 1915.
Section 2). The conductivity data (125ꢂ
150 Vꢄ1 cm2
/
molꢄ1 in 10ꢄ3 mol dmꢄ3 solutions in dry acetonitrile)
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