Reactivity of a cationic square-planar palladium(II) chloro complex containing bis[2-(diphenylphosphino)ethyl]amine: Chloro substitutions by anionic ligands and formation of neutral digold(I) compounds possessing linear PAuX fragments. The x-ray crystal structure of Au2[Ph2P(CH2)2N(NO) (CH2)2PPh2]Cl2

Article abstract of DOI:10.1039/b109675n

The interaction of sodium tetrachloropalladate(II) with the potentially tridentate aminophosphine bis[2-(diphenylphosphino)ethyl]amine (PNHP) in 1:1 molar ratio leads to the formation of the four-coordinate complex [Pd(PNHP)Cl]Cl (1). Complex 1 undergoes chloro substitution reactions with NaX (X = Br, I), CuCl, AgNO₃, the amino acid N-acetyl-L-cysteine (AcCysSH) and the tripeptide reduced glutathione (γ-L-Glu-L-Cys-Gly, GSH) affording [Pd(PNHP)X]X′ [X = X′ = Br (2), I (3), NO₃ (4); X = Cl, X′ = CuCl₂ (1a); X′ = Cl, X = RS = AcCysS (8), GS (9)]. However, gold(I) induces abstraction of the aminophosphine from the ionic complexes 1 and 2 to produce the neutral compounds Au₂(PNHP)X₂ [X = Cl (5), Br (6)]. The dinuclear complex Au₂(PN(NO)P)Cl₂ (5a), containing the ligand bis[2-(diphenylphosphino)ethyl]nitrosylamine, was formed by reaction of 4 with gold(I) in the presence of traces of nitrosyl chloride. Addition of one molar equivalent of PNHP to 1 results, by a ring-opening process, in the formation of [Pd(PNHP)₂]Cl₂ (7) in which the palladium is five-coordinate. The ionic complexes 1, 2 and 4 were shown by X-ray diffraction to be distorted square-planar and complex 2 has a N-H...Br bond of 2.371 A with the ligand adopting a boat conformation. The X-ray crystal structure of the novel neutral compound 5a shows linear P-Au-Cl arrangements with intermolecular Au...Au interactions of 3.0412(9) A.

Full text of DOI:10.1039/b109675n

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Reactivity of a cationic square-planar palladium(II) chloro complex
containing bis[2-(diphenylphosphino)ethyl]amine: chloro substitutions
by anionic ligands and formation of neutral digold(I) compounds
possessing linear PAuX fragments. The X-Ray crystal structure
of Au2[Ph2P(CH2)2N(NO)(CH2)2PPh2]Cl2
M. Ines Garcıa-Seijo,a Abraha Habtemariam,b Simon Parsons,b R. O. Gouldb and
M. Esther Garcıa-Fernandez*a
a
Department of Inorganic Chemistry, University of Santiago de Compostela,
E-15782 Santiago de Compostela, Spain. E-mail: qiegfq@usc.es
Department of Chemistry, University of Edinburgh, King’s Buildings, West Mains Road,
Edinburgh, UK EH9 3JJ
b
Received (in Montpellier, France) 22nd October 2001, Accepted 20th December 2001
First published as an Advance Article on the web
The interaction of sodium tetrachloropalladate(II) with the potentially tridentate aminophosphine
bis[2-(diphenylphosphino)ethyl]amine (PNHP) in 1 : 1 molar ratio leads to the formation of the four-coordinate
complex [Pd(PNHP)Cl]Cl (1). Complex 1 undergoes chloro substitution reactions with NaX (X ¼ Br, I), CuCl,
AgNO3 , the amino acid N-acetyl-L-cysteine (AcCysSH) and the tripeptide reduced glutathione (g-L-Glu-L-
Cys-Gly, GSH) affording [Pd(PNHP)X]X0 [X ¼ X0 ¼ Br (2), I (3), NO3 (4); X ¼ Cl, X0 ¼ CuCl2 (1a); X0 ¼ Cl,
X ¼ RS ¼ AcCysS (8), GS (9)]. However, gold(I) induces abstraction of the aminophosphine from the ionic
complexes 1 and 2 to produce the neutral compounds Au2(PNHP)X2 [X ¼ Cl (5), Br (6)]. The dinuclear complex
Au2(PN(NO)P)Cl2 (5a), containing the ligand bis[2-(diphenylphosphino)ethyl]nitrosylamine, was formed by
reaction of 4 with gold(I) in the presence of traces of nitrosyl chloride. Addition of one molar equivalent of
PNHP to 1 results, by a ring-opening process, in the formation of [Pd(PNHP)2]Cl2 (7) in which the palladium is
five-coordinate. The ionic complexes 1, 2 and 4 were shown by X-ray diffraction to be distorted square-planar
and complex 2 has a N–HÁ Á ÁBr bond of 2.371 A with the ligand adopting a boat conformation. The X-ray
+
crystal structure of the novel neutral compound 5a shows linear P–Au–Cl arrangements with intermolecular
AuÁ Á ÁAu interactions of 3.0412(9) A.
+
20
Ligands with mixed donor atoms have been the subject of
many studies in recent years.1–5 The higher water solubility of
transition metal complexes containing phosphorus-nitrogen-
phosphorus ligands compared to those with common
phosphines increases their potential application in catalytic
transformations.6 Due to the high trans influence of P, and
with an appropriate choice of substituents on both P and
N, Pt(II) aminophosphine complexes7 can bind to the DNA
bases guanine and thymine via a novel chelate ring-opening
mechanism and are cytotoxic to cancer cells. The presence of
other ligands such as sulfur-containing molecules can prevent
toxic side effects of these complexes under in vivo conditions.8
Palladium(II) complexes such as [pd(triphos)X]X (X ¼ Cl, Br, I)
show faster kinetics than platinum(II) complexes by reaction
with gold group metals.9a For further comparison purposes the
study of the chemistry of Pd(II) aminophosphine complexes
was considered of interest in this work.
On the other hand, gold(I) compounds with tertiary phos-
phines have been extensively studied,9b,c,10 due to the exhibi-
tion of anticancer activity for tetrahedral systems and the
usefulness of linear compounds in the treatment of rheumatoid
arthritis. The aurophilic interactions between linearly coordi-
nated Au(I) centres11 have the potential to self-assemble
superstructures through intermolecular contacts, with the
formation of supramolecular aggregates12 that in several cases
are strongly photo-luminescent.13,14 Although diphosphines
such as Ph2P(CH2)nPPh2 (n ¼ 1–8),15–19 Ph2P(CH=CH)PPh2
21
or Ph2P[CH2(C=CH2)CH2]PPh2 have been widely used to
form dinuclear gold(I) complexes, aminophosphines have been
used much less in gold chemistry.19,22,23 Since studies on metal
complexes containing the linear aminophosphine bis[2-
(diphenylphosphino)ethyl]amine (PNHP) are very limited,24,25
the aim of this work is to report novel reactions of
[Pd(PNHP)Cl]Cl with gold group metal compounds,26 thiols
and an excess of PNHP.
Experimental
General procedures
Dichloromethane was redistilled under nitrogen over CaCl2 .
Diphenylphosphine, palladium chloride and palladium
bromide were purchased from Strem Chemicals, potassium tert-
butoxide, bis(2-chloroethyl)amine hydrochloride, N-acetyl-L-
methionine, N-acetyl-L-cysteine and 2,20-thiodiethanol were
from Aldrich, sodium chloride, bromide and iodide from Pan-
reac, gold metal from S.E.M.P.S.A. and reduced glutathione
from Sigma. Solutions of N-acetyl-L-methionine, N-acetyl-L-
cysteine (AcCysSH) and reduced glutathione (GSH) were
degassed by bubbling with argon prior to use. THF was dried
over Na and freshly distilled before use.
636
New J. Chem., 2002, 26, 636–644
DOI: 10.1039/b109675n
This journal is # The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2002

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Microanalyses were performed at the University of Santiago
de Compostela. Fast atom bombardment (FAB) mass spectra
were obtained in a KRATOS MS 50 spectrometer using 3-
nitrobenzyl alcohol as the matrix. Infrared spectra were rec-
[Pd(PNHP)X]X [X ¼ Cl (1), Br (2), I (3)]. A suspension
of PdX2 (X ¼ Cl, 0.0743 g, 0.4188 mmol; X ¼ Br, 0.1115 g,
0.4188 mmol) and NaX (X ¼ Cl, 0.0489 g, 0.8376 mmol;
X ¼ Br, 0.1724 g, 1.6752 mmol) in H2O (15 mL) was heated on
a water bath (80 ꢀC) until a clear solution was obtained. This
was allowed to cool to room temperature. For the synthesis of
3 NaI (0.2511 g, 1.6752 mmol) was added as a powder to an
aqueous solution of Na2PdCl4 (0.4188 mmol). A solution of
PNHPÁHCl (0.2000 g, 0.4188 mmol) in CH2Cl2 (15 mL) was
added dropwise. The resultant solutions were stirred for 15 h
at room temperature and after that the organic phase was
extracted with CH2Cl2 , dried over anhydrous Na2SO4 and
filtered. The solvent was removed in vacuo to leave a yellow (1
and 2) or dark red (3) solid. Solids were recrystallised from
CH2Cl2–n-hexane (1 and 3) or CH2Cl2–acetone (2) solutions.
Crystals suitable for X-ray diffraction were obtained for 1
from a CD3OD–D2O–DMSO-d6 solution and for 2 from a
CH2Cl2–acetone solution.
orded at ambient temperature as KBr pellets (4000–500 cmÀ1
)
and Nujol mulls (500–100 cmÀ1) on a Mattson Cygnus 100
spectrophotometer. The bands are reported as vs ¼ very strong,
s ¼ strong, m ¼ medium, w ¼ weak, sh ¼ shoulder, b ¼ broad.
Electronic absorption spectra were recorded at 22 ꢀC (40 mM
sample concentration, MeOH–H2O–DMSO 3 : 3 : 2) on a
Shimadzu spectrophotometer with temperature control using 1
cm pathlength cells. 31P {1H} NMR spectra were recorded on a
Bruker AMX500 spectrometer at 202.46 MHz and a DMX500
NMR spectrometer at 202 MHz. Chemical shifts (d) are
reported relative to external 85% H3PO4 ; s ¼ singlet, d ¼
doublet, t ¼ triplet, J ¼ coupling constant in Hz.
The pHmeasurements were made using a Corning 240 pH
meter equipped with an Aldrich microcombination electrode
standardised with buffers at pH4, 7 and 10. For deuterated
and mixed solvents, the pHmeter readings are given without
correction and are designated as pH* values. Some of the
samples used for NMR spectroscopy were kept at room tem-
perature (ca. 22 ꢀC) for a few days and were diluted in order to
obtain positive electrospray ion mass spectra (ESI-MS) in a
Platform II mass spectrometer (Micromass, Manchester,
U.K.). Samples (10 to 100 mM) were injected in CD3OD–D2O–
DMSO-d6 using an infusion pump with a flow rate of
0.48 mL hÀ1. A source temperature of 75 ꢀC and a drying gas
flow rate of 450 L hÀ1 were found to be suitable parameters for
analysis. A potential of 2.8 kV was applied to the probe
capillary and a cone voltage of 50 V over 100–1000 Da was
used. The quadrupole was scanned at 100 amu sÀ1. The mass
accuracy of all measurements was within 0.1 m=z unit. Con-
ductivities were measured at 25 ꢀC using 10À3 M solutions in
DMF or CH3CN on a WTW model LF-3 instrument.
1: Yield: 90%, mp 172 ꢀC. Found: C, 52.4; H, 4.8; N, 2.2.
C28H31NOP2PdCl2 (1ÁH2O) requires: C, 52.7; H, 4.9; N, 2.3%.
IR nmax=cmÀ1 (Pd–Cl) 312s. MS (FAB): m=z 582 (Mþ À Cl,
100%); 547 (Mþ À 2Cl, 8%). ESI-MS (þ): m=z 582
([Pd(PNHP)Cl]þ). 31P {1H} NMR (CDCl3): dP 34.6s.
L (CH3CN or DMF) ¼ 47.2 or 22.8 ohmÀ1 cm2 molÀ1. UV
l=nm (e=MÀ1 cmÀ1) 356 (2,700), 290 (3,750).
2: Yield: 74%, mp 175 ꢀC. Found: C, 46.1; H, 4.2; N, 1.9.
C28H31NOP2PdBr2 (2ÁH2O) requires: C, 46.3; H, 4.3; N, 1.9%.
IR nmax=cmÀ1 (Pd–Br) 254s. MS (FAB): m=z 626 (Mþ À Br,
77%); 547 (Mþ À 2Br, 8%). 31P {1H} NMR (CDCl3): dP ¼
36.0s. L (CH3CN or DMF) ¼ 64.6 or 70.8 ohmÀ1 cm2 molÀ1
.
3: Yield: 71%, mp 239 ꢀC. Found: C, 40.9; H, 3.8; N, 1.7.
C28H31NOP2PdI2 (3ÁH2O) requires: C, 40.9; H, 3.8; N, 1.7%.
IR nmax=cmÀ1 (Pd–I) 190s. MS (FAB): m=z 673 (Mþ À I,
100%); 547 (Mþ À 2I, 10%). 31P {1H} NMR (CDCl3): dP ¼
37.9s. L (CH3CN or DMF) ¼ 116.8 or 85.8 ohmÀ1 cm2 molÀ1
.
Syntheses
[Pd(PNHP)Cl][CuCl2] (1a). CuCl (0.0192 g, 0.1939 mmol)
was added as a solid to a solution of [Pd(PNHP)Cl]ClÁH2O
(0.1200 g, 0.1886 mmol) in dry CH2Cl2 (20 mL) and the
reaction mixture was stirred for 16 h under nitrogen. The
resultant solution was filtered, the volume of the filtrate was
reduced and Et2O was added to precipitate the brown-greenish
complex, which was isolated by filtration and dried in vacuo.
Yield: 45%, mp 150 ꢀC (dec.). Found: C, 45.1; H, 4.3; N, 1.9.
C28H31NOP2PdCuCl3 (1aÁH2O) requires: C, 45.6; H, 4.3; N,
1.9%. IR nmax=cmÀ1 (Pd–Cl) 314s; (Cu–Cl) 296w. MS (FAB):
m=z 582 (Mþ À CuCl2 , 34%). 31P {1H} NMR (CDCl3): dP
Au(tdg)Cl. Solutions of Au(tdg)Cl27 (tdg ¼ thiodiglycol ¼
2,20-thiodiethanol) were prepared by treating Au (0.25 g, 1.269
mmol) with 2.5 mL HCl (36%) and 1.5 mL HNO3 (60%) on
an oil bath (120 ꢀC), followed by the addition of 2 Â 2.5 mL
HCl. The solution was then allowed to cool to room tem-
perature. Methanol (10 mL) was then added, the solution was
neutralised with CaCO3 and the resultant suspension was fil-
tered. The clear final filtrate containing tetrachloroauric acid
was reduced with 2,20-thiodiethanol (1 mL) until the colour
changed from yellow to colourless, to give Au(tdg)Cl in situ.
36.6s. L(CH3CN) ¼ 67.1 ohmÀ1 cm2 molÀ1
.
Au(tdg)Br. The same procedure was used to prepare solu-
tions of [Au(tdg)Br]28 by treating a concentrated solution of
HAuCl4 with KBr (1.3 g, 10.96 mmol) in Et2O–H2O (3 : 1,
20 mL). The organic phase was extracted with Et2O.
[Pd(PNHP)(ONO2)](NO3) (4). To a solution of [Pd(PNHP)
Cl]ClÁH2O (0.1500 g, 0.2357 mmol) in CHCl3 (18 mL), a
solution of AgNO3 (0.0906 g, 0.5333 mmol) in MeOH(20 mL)
was added dropwise and immediately a white precipitate of
AgCl was formed. The reaction mixture was kept for 20 h,
protected from light, then filtered and the solvents removed
from the filtrate in vacuo. The yellow-greenish solid was
recrystallised from CH2Cl2–n-hexane. Crystals suitable for
X-ray diffraction were obtained from a solution of the complex
in CDCl3 . Yield: 87%, mp 177 ꢀC (dec.). Found: C, 49.6; H,
4.9; N, 5.8. C29H33N3O7P2Pd (4ÁCH3OH) requires: C, 49.4; H,
PNHP. Bis[2-(diphenylphosphino)ethyl]amine (PNHP) was
prepared as an air-stable hydrochloride (PNHPÁHCl) using a
modification of a literature method.29,30 Diphenylphosphine
(14 mL, 15.0 g, 80.4 mmol) was added to a suspension of
potassium tert-butoxide (23.4 g, 208.5 mmol) in dry THF (450
mL) under argon. The resulting deep red solution was stirred
for 20 min and bis(2-chloroethyl)amine hydrochloride (7.1 g,
40.0 mmol) was added as a powder. The mixture was heated at
reflux for 28 h at 80 ꢀC and after that a 1 M solution of HCl
(ca. 100 mL) was added. After removing the solvents a white
solid precipitated and was dried in vacuo. It was recrystallised
from CH2Cl2–Et2O and washed with CH3CN. Yield: 60%, mp
155 ꢀC. Calcd for C28H30NP2Cl (PNHPÁHCl): C, 70.4; H, 6.3;
N, 2.9. Found: C, 70.1; H, 6.4; N, 3.0%. 31P {1H} NMR
(CDCl3): dP À 22.7s. IR nmax=cmÀ1 (N–H) 3300. MS (FAB):
442 (Mþ, 100%).
4.7; N, 5.9%. IR nmax=cmÀ1 (Pd–O) 346w; (N–O)ionic
nitrate
1340, 841m; (N–O)asym 1384vs, 1272m; (N–O)sym 1027w. MS
(FAB): m=z 609 (Mþ À NO3 , 41%); 547 (Mþ À 2NO3 , 100%).
31P {1H} NMR (CDCl3): dP 36.3s. L(CH3CN or
DMF) ¼ 182.3 or 111.9 ohmÀ1 cm2 molÀ1
.
Au2(PNHP)X2 [X ¼ Cl (5), Br (6)]. A solution of NaOH
(0.0126 g, 0.3150 mmol) in H2O (1.5 mL) was added to a
solution of PNHPÁHCl (0.1500 g, 0.3141 mmol) in CH2Cl2
New J. Chem., 2002, 26, 636–644
637

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(15 mL) and the mixture was stirred for 4 h. The organic
phase was extracted with CH2Cl2 , dried over anhydrous
Na2SO4 and filtered. To the filtrate another solution of
Au(tdg)X (0.1237 g of Au, 0.6282 mmol) in CH3OH(X ¼ Cl)
or Et2O (X ¼ Br), prepared as described above, was added
dropwise and the mixture was stirred for 15 h. Solvents were
removed in vacuo and a colourless oil appeared. It was stirred
with water, affording a white solid that was isolated by filtra-
tion, dried in vacuo and recrystallised from CH2Cl2–Et2O
(X ¼ Cl) or CH2Cl2–n-hexane (X ¼ Br).
Titrations
Titration of Na2PdCl4 and Au2(PNHP)Cl2 (5) with
PNHP·HCl. To a solution of Na2PdCl4 in H2O, prepared
in situ as described in the synthesis of complex 1, and to
a solution of Au2(PNHP)Cl2 (5) in CDCl3 solutions of
PNHPÁHCl in CDCl3 were added reaching different stoichio-
metric ratios. The 31P {1H} NMR spectrum of the organic
layer was recorded after every addition.
5: Yield: 53%, mp 169 ꢀC. Found: C, 37.3; H, 3.3; N, 1.5.
C28H29NP2Au2Cl2 requires: C, 37.1; H, 3.2; N, 1.5%. IR
Titration of [Pd(PNHP)Cl]Cl (1) with AgNO3 . A solution
of AgNO3 in CD3OD was added slowly to a solution of
[Pd(PNHP)Cl]ClÁH2O in CDCl3 and the mixture (1 : 1 stoi-
chiometric ratio) was left for 12 h in the absence of light. After
removing the AgCl precipitate, the 31P {1H} NMR spectrum
was recorded. This procedure was repeated after addition of
2 and 3 equiv. of AgNO3 .
n
max=cmÀ1 (Au–Cl) 326vs,b. MS (FAB): m/z 870 (Mþ À Cl,
100%); 638 (Mþ À Au À 2Cl, 13%). 31P {1H} NMR (CDCl3):
dP 22.0s. L(CH3CN) ¼ 8.4 ohmÀ1 cm2 molÀ1
.
6: Yield: 59%, mp 200 ꢀC (dec.). Found: C, 32.2; H, 3.2; N,
1.3. C28H33NO2P2Au2Br2 [(6)Á2H2O] requires: C, 32.6; H, 3.2;
N, 1.3%. IR nmax=cmÀ1 (Au–Br) 230w. MS (FAB): m=z 914
(Mþ À Br, 100%); 638 (Mþ À Au À 2Br, 7%). 31P {1H} NMR
(CDCl3): dP 25.8s. L(CH3CN) ¼ 15.2 ohmÀ1 cm2 molÀ1
.
Titration of [Pd(PNHP)X]X [X ¼ Cl (1), Br (2), I (3), NO3
(4)] and [Pd(PNHP)2]Cl2 (7) with Au(I). Solutions of Au(tdg)X
in CH3OH, prepared as described above, were added dropwise
to a solution of 1, 2, 4 or 7 in CDCl3 and after 12 h the 31P
{1H} NMR spectrum was recorded. Further additions to
complete 2 and 3 molar equiv. of Au(I) were done after the
same time interval. A similar procedure was followed for the
titration of complex 3 by addition of AuI as a solid.
Au2[PN(NO)P]Cl2 (5a). To
a solution of [Pd(PNHP)-
(ONO2)](NO3)ÁCH3OH(0.0134 g, 0.0190 mmol) in CDCl
3
(1.0 mL) a solution of Au(tdg)Cl (0.0037 g of Au, 0.0190 mmol)
in CH3OH( ꢁ1.0 mL), prepared as described above, was added
and the mixture was allowed to react for 24 h. Further addi-
tions of Au(I) to complete 3 equiv. were done after the same
time interval. Colourless crystals suitable for X-ray diffraction
were obtained after the solution had stood at ambient tem-
Crystallography
perature for 3 months. 31P {1H} NMR (CDCl3): dP 25.5 [1P, s,
Table 1 summarises the crystal data, data collection, structural
solution and refinement parameters for complexes 1ÁH2O,
2Á(CH3)2CO, 4ÁH2OÁCH3OHand 5a. A colourless plate of
1ÁH2O, a yellow block of 2Á(CH3)2CO, a yellow tablet of
4ÁH2OÁCH3OHand a colourless block of 5a were mounted on
glass fibers and used for data collection. A SMART APEX
CCD area detector was used for 1ÁH2O and a Stoe Stadi4 four-
circle diffractometer equipped with an Oxford Cryosystem
variable temperature device for the other complexes. Graphite
monochromated Mo-Ka radiation was used for 1ÁH2O,
2Á(CH3)2CO and 5a, and Cu-Ka radiation was used for data
collection of 4ÁH2OÁCH3OH. A SADABS31 or psi-scan32
absorption correction was made for 1ÁH2O and 5a, respec-
tively, while it was optimised numerically for 2Á(CH3)2CO and
4ÁH2OÁCH3OH.
0
PB], 24.6 [1P, s, PB ].
[Pd(PNHP)2]Cl2 (7). A suspension of PdCl2 (0.0557 g,
0.3141 mmol) and NaCl (0.0367 g, 0.6283 mmol) in H2O
(10 mL) was heated on a water bath (80 ꢀC) until a clear
solution was obtained. This was allowed to cool to room
temperature and a solution of PNHPÁHCl (0.3000 g, 0.6283
mmol) in CH2Cl2 (15 mL) was added dropwise. The resultant
solution was stirred for 1 h at room temperature, the organic
phase was extracted with CH2Cl2 , dried over anhydrous
Na2SO4 and filtered. The solvent was removed from the filtrate
in vacuo to leave a crystalline yellow solid. Yield: 85%, mp
130 ꢀC. Found: C, 56.7; H, 5.2; N, 2.4. C58H62N2P4PdCl6
[(7)Á2CH2Cl2)] requires: C, 56.6; H, 5.1; N, 2.3%. IR nmax=cmÀ1
(M–P) 367sh, 345m, 317s,b. MS (FAB): m=z 988 (Mþ À 2Cl,
12%); 561 (Mþ À 2Cl À 2C2H4PPh2 , 9%); 547 (Mþ À 2Cl À
PNHP, 84%). 31P {1H} NMR (CDCl3): dP 45.2 [2P, d,
The structures of 1ÁH2O, 4ÁH2OÁCH3OHand 5a were solved
by direct methods, using the progam SHELXS-9733 (1ÁH2O
and 5a) and SIR9234 (4ÁH2OÁCH3OH), and by Patterson
methods (DIRDIF)35 for 2Á(CH3)2CO. The structures were
refined by full-matrix least-squares techniques on F2 using the
program SHELXL-97.36 Hydrogen atoms were placed geo-
metrically and positional parameters were refined using a
riding model, except for 1ÁH2O for which a mixed model was
used. Hydrogen atoms of water molecules were not included
for 1ÁH2O and 4ÁH2OÁCH3OH.
2
2J(PA,PB) ¼ ꢁ23.0 Hz, PA], 15.4 [1P, t, J(PA,PB) ¼ ꢁ23.0 Hz,
PB], À22.8 [1P, s, PC].
[Pd(PNHP)(SR)]Cl [RSH ¼ AcCysSH (8), GSH ¼ (9)]. To a
suspension of 1ÁH2O (0.0100 g, 0.0157 mmol) in CD3OD (0.3
mL) a solution of AcCysSH(0.0026 g, 0.0160 mmol) or GSH
(0.0049 g, 0.0160 mmol) in D2O (0.3 mL) was added slowly
and the colour of the solution turned from light to dark yellow.
The reaction mixture was left for 18 h and after that DMSO-d6
(0.2 mL) was added, the pHwas measured and 31P {1H} NMR
spectra were recorded. Another molar equivalent of AcCysSH
(0.0026 g, 0.0160 mmol) or GSH(0.0049 g, 0.0160 mmol)
in D2O (0.1 mL) was added and the same procedure was
repeated.
CCDC reference numbers 181546–181549. See http://
www.rsc.org/spdata/nj/b1/b109675n/ for crystallographic data
in CIF or other electronic format.
Results and discussion
Syntheses
8: ESI-MS (þ): m/z 709.4 ([Pd(PNHP)(AcCysS)]þ). 31P {1H}
NMR (CD3OD–D2O–DMSO-d6 , pH *ꢁ 2.1): dP 39.8s. UV
l=nm (e=MÀ1 cmÀ1) 300 (14,750), 450 (780).
Treatment of a solution of PNHPÁHCl in dichloromethane
with sodium hydroxide in a 1 : 1 stoichiometric ratio led to the
free amine. Scheme 1 shows the complexes prepared in this
work with their phosphorus atoms labelled.
By reaction of an aqueous solutions of PdX4 with the
hydrochloride salt of PNHP dissolved in dichloromethane,
9: ESI-MS (þ): m=z 853.4 ([Pd(PNHP)(GS)]þ). 31P {1H}
NMR (CD3OD–D2O–DMSO-d6 , pH *ꢁ 2.9): dP 40.1 [1P, s,
0
PA], 40.0 [1P, s, PA ]. UV l=nm (e=MÀ1 cmÀ1) 300 (15,650), 450
(900).
2À
638
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Table 1 Summary of crystal parameters, data collection and refinement for 1ÁH2O, 2Á(CH3)2CO, 4ÁH2OÁCH3OHand 5a
1ÁH2O
2Á(CH3)2CO
4ÁH2OÁCH3OH
5a
Empirical formula
Formula weight=g molÀ1
T=K
l=A
Crystal system
C
28H31Cl2NP2OPd
C31H35Br2NP2OPd
765.76
150(2)
C29H35N3P2O8Pd
721.94
220(2)
C28H28Cl2N2P2OAu2
935.30
293(2)
0.71073 (Mo)
Monoclinic
P21=n
14.120(3)
12.871(3)
16.849(3)
90.00
109.72(3)
90.00
2882.5(10)
4
2.155
10.489
5066
5066
0.000
0.0515
0.0966
636.78
100(2)
0.71073 (Mo)
Monoclinic
P21=c
20.245(3)
15.725(2)
17.788(2)
90
104.492(2)
90
5482.8(12)
8
1.543
+
0.71073 (Mo)
Triclinic
P1
1.54178 (Cu)
Triclinic
P1
-
-
Space group
+
a=A
+
11.722(4)
12.209(4)
12.640(4)
114.823(13)
101.696(19)
98.816(17)
1548.8(8)
2
1.642
3.307
6158
5495
8.044(5)
12.719(5)
15.492(7)
76.89(3)
82.59(4)
89.47(4)
1530.6(13)
2
1.566
6.343
6923
5034
b=A
+
c=A
a=ꢀ
b=ꢀ
g=ꢀ
+
U=A3
Z
Calcd density=Mg mÀ3
m=mmÀ1
1.011
Reflec. collected
Indep. reflect.
Rint
R1 (final)
wR2 (final)
36 343
11 191
0.1300
0.0580
0.1342
0.0833
0.0466
0.1104
0.0272
0.0733
0.2161
respectively. The addition of CuCl, AgNO3 and AcCysSHor
GSHto solutions of complex 1 in CHCl3 or CD3OD did not
cause any ring-opening;26 compounds [Pd(PNHP)Cl][CuCl2]
(1a), [Pd(PNHP)(ONO2)]NO3 (4) and [Pd(PNHP)(AcCysS)]Cl
(8) or [Pd(PNHP)(GS)]Cl (9), respectively, were obtained.
Complexes 5 and 6 were prepared as solids by reaction of the
free amine with 2 equiv. of Au(tdg)X (X ¼ Cl, Br). Both
complexes can also be obtained by reaction of gold(I) with the
hydrochloride form of the ligand, but in lower yields. Attempts
to prepare Au2(PNHP)I2 were unsuccessful. Likewise, com-
plexes [Pd(PNHP)2]X2 (X ¼ Br, I) could not be prepared.
Crystals suitable for X-ray diffraction of Au2(PN(NO)P)Cl2
(5a) were afforded by slow evaporation of a CDCl3–CH3OH
solution containing a mixture of 4 and Au(tdg)Cl in a 1 : 3
stoichiometric ratio. The formation of this dinuclear com-
pound with the nitrosylaminophosphine ligand can be
explained by the presence in the Au(I) solution of traces of
nitrosyl chloride coming from the aqua regia used for digestion
of gold.
Compounds 1, 1a, 2, 3 and 6 gave satisfactory microanalyses
for hydrates, while 4 and 7 were isolated as methanol and
dichloromethane solvates, respectively.
Characterization
Molar conductivities. Complexes 1, 1a and 2 do not behave
as conductors in 10À3 M CH3CN solutions,37 which could be
due to ion pair formation.
31P {1H} NMR spectroscopy of the complexes. The 31P {1H}
NMR spectra for complexes 1, 1a, 2, 3 and 4 (Table 2) showed
a singlet in agreement with symmetry equivalent phosphorus
atoms (PA) of the aminophosphine. These resonances are
shifted downfield from that of the free ligand (coordination
shifts, Dd, 57.3, 59.3, 58.7, 60.6 and 59.0 respectively), as
expected for chelated ligands.38 The NMR data are therefore
consistent with the formation of distorted square-planar
complexes where the palladium is bound to the three donor
atoms of PNHP and to one halide or nitrate (4). Similar
structures were previously found in solution for analogous
Scheme 1 Reactivity of [Pd(PNHP)Cl]Cl (1) to form ionic (1a, 2–4,
7–9) and neutral (5) complexes. Reaction between 2 or 4 and
Au(tdg)Cl to form 5a.
complexes
with
bis[2-(diphenylphosphino)ethyl]phenyl-
complexes 1–3 and 7 were obtained as solids from the organic
phase.26 This procedure constitutes a slight variation of a lit-
erature method.24b A metathesis reaction of complex 1 with 2
equiv. of NaX (X ¼ Br, I) also led to compounds 2 and 3,
phosphine (triphos).26,39–42
Complex 7 showed three signals: a singlet at d À 22.8 (PC), a
triplet centred at d 15.4 (PB) and a doublet centred at d 45.2
(PA), the coupling constant J(PA,PB) being ca. 23.0 Hz. On
2
New J. Chem., 2002, 26, 636–644
639

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Table 2 31P {1H} NMR data for complexes and reactions
d (PA)
the spectrum of 9 around 40 ppm seem to indicate the
non-equivalence of the phosphorus atoms, probably due to the
chiral a-CHof the glutathione.
d (PB)
Similar reactions between S-containing molecules and
monofunctional platinum chloride complexes such as
1a
34.6(s)
37.9(s)
40.1(s)
34.1(s)
b
1 þ AgNO3
[Pt(dien)Cl]þ43
or
[Pt(terpy)Cl]þ44
(dien ¼ diethylene-
b
1 þ 2 AgNO3
triammine, terpy ¼ 2,20,60,200-terpyridine) have been reported.
However, the triphos complex [Pt(triphos)Cl]þ did not react
with thiols.26 It was necessary to replace the chloride ligand by
a good leaving group such as nitrate to prepare the thiolate
complexes or the acetylmethionine derivative. Complex 1 as
well as [Pt(terpy)Cl]þ did not react with the amino acid
N-acetyl-L-methionine.44
1 þ 1 Au(tdg)Clc
1 þ 2 Au(tdg)Clc
1 þ 3 Au(tdg)Clc
1aa
21.9(s)
21.8(s)
21.8(s)
36.6(s)
36.0(s)
36.5(s)
2a
2 þ 1 Au(tdg)Cld
2 þ 2 Au(tdg)Cld
2 þ 3 Au(tdg)Cld
3a
24.0(s)
24.0(s)
24.0(s)
37.9(s)
36.7(s)
36.7(s)
36.7(s)
36.3(s)
33.9(s)
33.8(s)
3 þ 1 AuIa
3 þ 2 AuIa
3 þ 3 AuIa
4a
Reactions with excess ligand. A solution of Na2PdCl4 in
H2O was titrated with PNHPÁHCl (CDCl3) in different molar
ratios. The appearance in the spectrum of a singlet at d 34.7
after the addition of 0.25 molar equiv. of the ligand indicated
formation of complex 1 (Scheme 1). When 1.0 molar equiv. of
PNHP was added no new signals appeared in the spectrum.
Subsequent additions of aminophosphine gave rise to three
new signals: a doublet at d 45.3, a triplet at d 15.3 and a singlet
at d À22.5, which coexist with the singlet due to complex 1.
When the metal : ligand ratio was 1 : 2, the three new signals
were the only resonances in the spectrum. The presence of
these signals is consistent with the formation of complex 7
(vide supra).
Ligand exchange reactions were observed by titration of
Au2(PNHP)Cl2 with aminophosphine. Addition of 0.5 equiv.
of PNHP to a CDCl3 solution of complex 5 leads to a
broadening of the signal at d 22.0 and the appearance of a new
signal at d 33.8, indicating the existence of two different gold-
phosphorus environments. With a 1 : 1 stoichiometric ratio the
spectrum shows only one signal at d 33.7, consistent with one
type of phosphorus atom in a likely annular structure. Sub-
sequent additions of the aminophosphine result in a broad-
ening of this signal.
4 þ 1 Au(tdg)Clc
4 þ 2 Au(tdg)Clc
4 þ 3 Au(tdg)Clc
5a
22.0(s)
22.0(s)
22.0(s)
22.0(s)
25.5(s) f
25.8(s)
15.4(t)g
22.1(s)
22.0(s)
22.0(s)
22.0(s)
5ae
6d
7a
45.2(d)g
33.9(s)
33.6(s)
33.5(s)
7 þ 1 Au(tdg)Clc
7 þ 2 Au(tdg)Clc
7 þ 3 Au(tdg)Clc
7 þ 4 Au(tdg)Clc
1h,i
36.0(s)
37.9(s)
37.4(s)
39.7(s)
39.8(s)
37.4(s)
40.0(s)=39.9(s)
40.1(s)=40.0(s)
1 þ 2 AcMeth
1 þ 1 AcCysSHh
1 þ 2 AcCysSH( 8)h
1 þ 1 GSHh
1 þ 2 GSH( 9)h
a
b
Spectrum in CDCl3 . Spectrum in CDCl3–CD3OD. Spectrum in
c
d
CDCl3–CH3OH. Spectrum in CDCl3–Et2O. Spectrum in CDCl3–
e
CD2Cl2 . d(PB’) ¼ 24.6(s).
2J(PA,PB) ¼ ꢁ23.0 Hz, d(PC) ¼
f
g
h
i
À22.8(s). Spectrum in CD3OD–D2O–DMSO-d6 . ÀpH* ꢁ 7.4.
Reactions with metal salts. By addition of 1 equiv. of
AgNO3 in CDCl3–CD3OD to complex 1 the signal at d 34.6
shifts downfield to d 37.9. A single signal at d 40.1 appears
when the second equivalent is added. This indicates the
replacement in complex 1 of the chloride counterion and the
ligand by nitrate with formation of complex 4 (Scheme 1).
Similar results were previously observed for analogous triphos
compounds,41 indicating that AgNO3 does not induce any
chelate ring-opening.
the basis of the multiplicity and the integration (1 : 1 : 2) the
31P {1H} NMR data suggest the formation of a five-coordinate
complex with the two aminophosphines arranged around the
palladium in a square pyramidal structure24b (Scheme 1).
Attempts to isolate the analogous bromide and iodide com-
plexes led to 31P {1H} NMR spectra characteristic of mixtures
of [Pd(PNHP)X]X and [Pd(PNHP)2]X2 .
Complexes 5 and 6 [Au2(PNHP)X2] showed only one reso-
nance in the 31P {1H} NMR spectrum at d 22.0 and 25.8,
respectively, indicating that both phosphorus atoms of the
linear P–Au–X fragments are equivalent.19,27c However, the
31P {1H} NMR spectrum of Au2[PN(NO)P]Cl2 (5a) showed
two very close resonances: a singlet at d 25.5 and another peak
at d 24.6, indicating inequivalent phosphorus atoms.
The 31P {1H} NMR spectrum of a mixture containing
[Pd(PNHP)X]X (1, 2) and Au(tdg)X (X ¼ Cl, Br) in CDCl3–
MeOHand CDCl 3–Et2O, respectively, in a 1 : 1 stoichiometric
ratio showed two singlets with very similar intensities at d 34.1
and 21.9 (X ¼ Cl) and d 36.5 and 24.0 (X ¼ Br). Further
additions of 2 or 3 equiv. of Au(I) showed in both cases the
disappearance of the signal at lower field assigned to com-
plexes 1 (X ¼ Cl) and 2 (X ¼ Br). The signal around d 23.0 was
assigned to the linear P–Au–X fragments45 in the neutral
dinuclear complexes Au2(PNHP)X2 [X ¼ Cl (5), Br (6)]. With
the first addition, Au(I) abstracts the aminophosphine from the
palladium complex, which coexists in solution with the neutral
dinuclear species [eqn. (1a)]. An excess of Au(I) leads to
complexes 5 or 6 as the only aminophosphine derivatives
[eqn. (1b)].
Reactions with biologically relevant molecules. The 31P {1H}
NMR spectrum of a CD3OD–D2O–DMSO-d6 solution con-
taining complex [Pd(PNHP)Cl]Cl (1) and AcCysSHor GSHin
a 1 : 1 molar ratio at pH* ca. 2.2 or 2.9, respectively, showed,
besides a small signal due to unreacted complex 1, other
resonance at d 39.7 or d 40.0 and 39.9 indicating the forma-
tion of new species. With the addition of another molar
equivalent of the biomolecule the former peak was the only
2 [Pd(PNHP)X]X þ 2 Au(tdg)X
! [Pd(PNHP)X]X þ Au2(PNHP)X2 þ Pd(tdg)2X2 (1a)
signal present in the spectra, confirming that AcCysSHor
þ
GSHdisplaces the chloride ligand from [Pd(PNHP)Cl]
afford the new thiolate complexes [Pd(PNHP)(SR)]Cl
to
[Pd(PNHP)X]X þ 2 Au(tdg)X
[SR ¼ AcCysS (8), GS (9)] (Scheme 1). The two signals in
! Au2(PNHP)X2 þ Pd(tdg)2X2
(1b)
640
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Scheme 2 Abstraction of PNHP from [Pd(PNHP)X]X (X ¼ Cl, Br) and ring-opening of [Pd(P3)X]X [X ¼ Cl, Br, I; P3 ¼ PhP(CH2CH2-
PPh2)2] induced by Au(I)X.
A different behaviour was observed for the analogous triphos
complex [Pd(triphos)Cl]Cl, which forms the heterobimetallic
compound PdAu(triphos)Cl3 by interaction with Au(I)26 via
ring-opening (Scheme 2). However, in both cases when starting
from the square-planar ionic complexes [Pd(L)Cl]Cl (L ¼
PNHP, triphos) neutral species containing linear gold(I) were
obtained.
in square-planar palladium(II) complexes, while the intense
band in the ultraviolet is a charge transfer in nature.47
Infrared spectroscopy. A broad band between 3400 and
48,49
3500 cmÀ1 assignable to the N–Hvibration
was observed
in the near infrared spectra (4000–500 cmÀ1) of complexes 1–7.
This band, present at 3300 cmÀ1 in the IR spectrum of the free
amine, is shifted to higher energy as a result of the com-
plexation. Bands corresponding to the n(N–O) vibrations for
complex 4, as well as a shoulder at 1340 cmÀ1 characteristic for
uncoordinated nitrate, were in agreement with the presence of
both nitrate ligand and counterion. The far infrared spectra
(500–100 cmÀ1) of 1–3 and 1a showed strong bands assigned to
Pd–X stretchs corresponding to terminal bonds.50a For 1a a
Similar results as for
1 and 2 were found when
[Pd(PNHP)(ONO2)](NO3) (4) was titrated with Au(I) (Table 1).
After the first addition of Au(tdg)Cl a mixture containing
complexes 4 and 5 was observed. Further additions of Au(I)
leads to complex 5 as the only aminophosphine compound
formed. However, the reaction of [Pd(PNHP)I]I (3) with AuI
did not cause any change in the 31P {1H} NMR spectrum,
indicating that gold(I) iodide does not abstract the amino-
phosphine from 3 and consequently complex Au2(PNHP)I2
was not formed.
weak band at 296 cmÀ1 due to n(Cu–Cl) of the linear CuCl2
À
group was also observed.50b The terminal Au–X stretches51,52
for 5 and 6 appeared as very strong and weak bands at 326 and
230 cmÀ1, respectively.
The 31P {1H] NMR spectrum of a mixture containing
[Pd(PNHP)2]Cl2 (7) and Au(tdg)Cl in CDCl3–MeOHin a 1 : 1
stoichiometric ratio showed a singlet at d 33.9 corresponding
to complex 1 and a very small signal at d 22.1 assigned to the
dinuclear complex 5 (Table 1). When 4 equiv. of Au(I) were
added the dinuclear complex 5 was the only aminophosphine
compound observed [eqn. (1c)].
Crystallography
Perspective views of the molecular structures and numbering
schemes of complexes 1ÁH2O, 2Á(CH3)2CO, 4ÁH2OÁCH3OH
and 5a are shown in Figs. 1 and 2. Selected bond lengths and
angles are listed in Tables 3 and 4. Walther et al.25 previously
reported the crystal structure of the chloro complex, solved at
293 K in space group P21=n, there showing the unit cell with
Z ¼ 2.
[Pd(PNHP)2]Cl2 þ 4 Au(tdg)Cl
! 2 Au2(PNHP)Cl2 þ [Pd(tdg)4]Cl2
(1c)
Mass spectrometry. In the FAB mass spectra of complexes
[Pd(PNHP)X]X0 the most intense peak corresponds to the
fragment [Mþ À X0], this pattern of fragmentation being ana-
logous to that found for similar triphos complexes.26 For
[Pd(PNHP)(ONO2)](NO3) (4) a peak at m=z 547 due to the loss
of both nitrate ligand and counterion exhibits an abundance of
100%. The presence of a peak at m=z 988 for [Pd(PNHP)2]Cl2
(7) confirms the formation of [Pd(PNHP)2]2þ as was pre-
viously observed for [M(triphos)2][SnPh2Cl3]2 complexes.46
The most abundant peak for Au2(PNHP)X2 complexes cor-
responds to the Au2(PNHP)X fragments. The ESI-MS (þ) for
8 and 9 reveal the presence of [Pd(PNHP)(SR)]þ ions.
Palladium(II) exhibits a distorted square-planar geometry in
complexes 1, 2 and 4. The aminophosphine is a tridentate
chelate ligand bound through the two P atoms and the nitrogen
(PNP), the fourth coordination position is occupied by a halide
(1 and 2) or nitrate (4), which acts as a monodentate ligand. The
other halide or nitrate is a counteranion. The complexes are
isostructural with [Ni(PNHP)Cl]Cl and show analogous
structures to [Pd(triphos)X]X (X ¼ Cl, Br, I).39,42,53 The Pd–N
+
bond lengths [2.061(5) average and 2.070(5) A for 1 and 2,
respectively] are essentially the same as the literature value of
+
2.041 A54 and not significantly different from that found in
[Pd(COOMe){2-(CHPPh2)-6-(CH2PPh2)pyridine}]55 where the
PNP ligand forms two chelate rings around Pd(II). As expected,
the weaker trans influence of the Pd–O bond compared to Pd–
Electronic absorption spectroscopy. Complexes 8 and 9
absorb at higher wavelengths [ca. 450 (ꢁ850 MÀ1 cmÀ1) and
300 nm (ꢁ15,000 MÀ1 cmÀ1)] compared to 1. The broad band
in the visible region is probably due to spin allowed transitions
+
X41 leads to a Pd–N bond distance for 4 [2.021(7) A] shorter
than in the halide complexes 1 or 2. However, the greater size
and trans influence of bromide than chloride causes a very
New J. Chem., 2002, 26, 636–644
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Fig. 2 ORTEP diagram for 5a.
the values of the angles P–Pd–P and N–Pd–X, all of which are
less than 180ꢀ. However, this distortion is not greater in 4 than
in 1 or 2, probably due to the disposition of the nitrate plane
almost perpendicular to the coordination plane, reducing the
steric hindrance around the metal.
The nitrate ligand has trigonal planar geometry with slightly
distorted O–N–O angles [125.6(1), 119.7(9) and 114.7(1)ꢀ]. The
coordination is also reflected in the larger N–O distance for the
+
oxygen bound to palladium(II) [1.344(1) A] compared to those
+
for the uncoordinated oxygen atoms [1.195(1) and 1.228(1) A].
This is a consequence of the decrease in the nitrogen–oxygen
bond order.
Due to the free rotation about the C–C bonds in the ethylene
chains of the ligand complex 2 seems to adopt a boat con-
formation. [Fig. 1(b)] that was not observed for 1 and 4
[Fig. 1(a) and (c)]. Complex 2 shows N–HÁ Á ÁBr hydrogen
+
bonds of 2.371 A, involving the Br counteranion.57 This short
+
interaction is not observed in 1 or 4 (N–HÁ Á ÁCl ca. 7.184 A or
+
N–HÁ Á ÁO ca. 6.211 A).
The X-ray crystal structure of Au2[PN(NO)P]Cl2 (5a) cor-
responds to a neutral dinuclear complex where the gold
atoms are bridged by the aminophosphine through the two
P atoms, the nitrogen being uncoordinated.15–21 Au(I) com-
pletes its coordination with a chlorine atom resulting in linear
P–Au–Cl fragments. As far as we know this is the first
X-ray crystal structure containing the difunctional ligand
(NO)N(CH2CH2PPh2)2 [PN(NO)P], which has a nitrosyl
group on the nitrogen. On the basis of the 31P {1H} NMR data
previously discussed for complexes 5, 5a and 6, an identical
structure can be proposed for all 3 complexes in the solid state
with the only difference due to the nitrosyl substituent on the
nitrogen for 5a.
Complex 5a has a gauche-skew conformation regarding the
relative orientation of the two Ph2PAuCl groups at the central
nitrogen atom. This conformation allows for a short inter-
Fig. 1 ORTEP diagram for: (a) one of the cations [Pd(PNHP)Cl]þ of
1 in the asymmetric unit [cation A: Pd(1), Cl(1); cation C: Pd(2), Cl(2)],
(b) [Pd(PNHP)Br]Br (2) and (c) cation [Pd(PNHP)(ONO2)]þ of 4.
+
molecular AuÁ Á ÁAu contact of 3.041(9) A almost perpendicular
to the axis determined by the linear P–Au–Cl fragments and
could be responsible for a potential luminescent activity.58 Such
a gold(I)–gold(I) interaction observed between adjacent mole-
cules of 5a is in the range characteristic of attractive aurophilic
slight increase in the Pd–N bond length from 1 to 2. On the
other hand the smaller trans influence of the nitrogen over the
bonds.11a,b,23,59–61 This value is analogous to the intermolecular
+
phosphorus56 produces Pd–X bond lengths in 1 and 2 [Pd–Cl ¼
AuÁ Á ÁAu distance (3.048 A) found in the trinuclear complex
+
2.3051(2) average and Pd–Br ¼ 2.418(1) A, respectively] shorter
Au3(tripod)Br3 [tripod ¼ 1,1,1-tris(diphenylphosphinomethyl)-
than those for triphos complexes26,53 and the usual literature
ethane] containing P–Au–Br linear fragments62a, shorter than
+
+
the intramolecular interaction in Au2(dppm)Cl2 (3.351 A)15
+
values.54 The Pd–O bond length of 4, 2.041(6) A, is also shorter
than the same distance for [Pd(triphos)(ONO2)](NO3) [2.127(4)
and close to the intramolecular AuÁ Á ÁAu distance (3.091 A) for
+
A].41 The Pd–P distances for 1 are in the expected range for
Au3(tripod)Cl3 .62b The Au–P and Au–Cl bond lengths are very
close to those found in other complexes with linear and tripodal
phosphines.16–18,20,21,62a The shortening of the Au–P bond
compared to the Au–Cl bond may be attributed to some metal-
to-ligand dp-dp back bonding.11,15,18,62b,c
other similarly arranged Pd(II) compounds.55
The P–Pd–N and P–Pd–X angles for 1, 2 and 4, below and
above 90ꢀ, respectively, show the distorted square-planar
environment at palladium. This distortion is also reflected in
642
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+
Table 3 Selected distances (A) and angles (ꢀ) for complexes 1ÁH2O, 2Á(CH3)2CO and 4ÁH2OÁCH3OH
1ÁH2O
2Á(CH3)2CO
4ÁH2OÁCH3OH
Pd(1)–P(1A)
Pd(1)–P(7A)
Pd(2)–P(1C)
Pd(2)–P(7C)
Pd(1)–N(4A)
Pd(2)–N(4C)
Pd(1)–Cl(1)
Pd(2)–Cl(2)
P(1A)–Pd(1)–P(7A)
P(1C)–Pd(2)–P(7C)
N(4A)–Pd(1)–P(1A)
N(4A)–Pd(1)–P(7A)
N(4C)–Pd(2)–P(1C)
N(4C)–Pd(2)–P(7C)
P(1A)–Pd(1)–Cl(1)
P(7A)–Pd(1)–Cl(1)
P(1C)–Pd(2)–Cl(2)
P(7C)–Pd(2)–Cl(2)
N(4A)–Pd(1)–Cl(1)
N(4C)–Pd(2)–Cl(2)
2.2973(2)
Pd(1)–P(7)
Pd(1)–P(1)
2.299(2)
2.301(2)
2.316(2)
2.308(2)
2.3060(2)
2.3021(2)
2.3172(2)
2.065(5)
2.056(5)
2.3082(2)
2.3019(2)
Pd(1)–N(4)
2.070(5)
2.418(1)
—
168.76(6)
2.021(7)
Pd(1)–Br(1)
Pd(1)–O(1)
P(7)–Pd(1)–P(1)
—
2.041(6)
167.34(8)
168.37(7)
168.86(7)
84.41(2)
84.43(2)
84.37(2)
84.73(2)
95.26(6)
96.12(6)
94.04(6)
96.94(7)
175.76(2)
177.40(2)
N(4)–Pd(1)–P(1)
N(4)–Pd(1)–P(7)
84.27(2)
84.51(2)
84.17(2)
84.51(2)
P(7)–Pd(1)–Br(1)
P(1)–Pd(1)–Br(1)
P(1)–Pd(1)–O(1)
P(7)–Pd(1)–O(1)
N(4)–Pd(1)–Br(1)
N(4)–Pd(1)–O(1)
O(2)–N(1)–O(3)
O(2)–N(1)–O(1)
O(3)–N(1)–O(1)
94.87(5)
96.37(5)
—
—
95.31(2)
95.73(2)
—
177.2(3)
125.6(1)
119.7(9)
114.7(1)
177.39(1)
—
+
Table 4 Selected distances (A) and angles (ꢀ) for complex 5a
Au(1)–P(1)
Au(2)–P(2)
Au(1)–Cl(1)
Au(2)–Cl(2)
P(1)–Au(1)–Cl(1)
P(2)–Au(2)–Cl(2)
P(1)–Au(1)–Au(2)_1
P(2)_1–Au(2)_1–Au(1)
N(1)–N(2)–O(3)
2.236(3)
2.243(4)
2.308(4)
2.295(4)
171.82(2)
176.20(2)
114.56(9)
95.50(9)
111.6(2)
Au(1)–Au(2)_1
N(1)–N(2)
N(2)–O(3)
Cl(1)–Au(1)–Au(2)_1
Cl(2)_1–Au(2)_1–Au(1)
C(22)–N(1)–N(2)
3.0412(9)
1.338(2)
1.193(2)
73.44(9)
87.19(2)
113.1(2)
124.8(2)
122.0(2)
C(12)–N(1)–N(2)
C(22)–N(1)–C(12)
+
The N–N distance [1.338(2) A] is characteristic of a single
bond while the N–O bond length [1.193(2) A] is very close to
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The authors thank the Xunta de Galicia, University of San-
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