Synthesis, characterization and solubility studies of four new highly water soluble 1,3,5-triaza-7-phosphaadamantane (PTA) salts and their gold(I) complexes

Article abstract of DOI:10.1016/j.poly.2010.03.012

The synthesis of new water soluble N-alkylated derivatives of 1,3,5-triaza-7-phosphaadamantane is presented. The compounds were characterized by means of NMR and IR spectroscopy, mass spectrometry, high resolution mass spectrometry, elemental analysis and

Full text of DOI:10.1016/j.poly.2010.03.012

Polyhedron 29 (2010) 1925–1932
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Synthesis, characterization and solubility studies of four new highly water
soluble 1,3,5-triaza-7-phosphaadamantane (PTA) salts and their gold(I) complexes
b
c
d
e
Sascha Schäfer a, , Wolfgang Frey , A. Stephen K. Hashmi , Vesna Cmrecki , Asunción Luquin ,
*
Mariano Laguna e
a Cardiff University, School of Chemistry, Park Place, Main Building, CF10 3AT, United Kingdom
b University of Stuttgart, Institut für Organische Chemie, Pfaffenwaldring 55, 70569 Stuttgart, Germany
c University of Heidelberg, Organisch-Chemisches Institut, Im Neuenheimer Feld 270, 69120 Heidelberg, Germany
d University of Düsseldorf, Forschungszentrum Jülich, Institut für Bioorganische Chemie, Stetternicher Forst, Geb. 15.8, 52426 Jülich, Germany
e University of Zaragoza, Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, C.S.I.C, 50009 Zaragoza, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
The synthesis of new water soluble N-alkylated derivatives of 1,3,5-triaza-7-phosphaadamantane is pre-
sented. The compounds were characterized by means of NMR and IR spectroscopy, mass spectrometry,
high resolution mass spectrometry, elemental analysis and X-ray diffraction analysis. The water solubility
of these compounds was found to be up to an astonishing 1450 g/L. Several different reactions were per-
formed utilizing these highly interesting compounds as starting materials. It was shown that the substi-
tution of the counter ion can be performed easily. Also transformations at the PTA framework were
possible, as shown by an ester cleavage example. To prove that the resulting PTA derivatives are compe-
tent as ligands for transition metals, gold(I) complexes were synthesized, using Au(tht)Cl as the metal
source. The resulting gold(I) complexes were characterized by 1H NMR and IR spectroscopy, mass and
high resolution mass spectrometry or elemental analysis.
Received 27 January 2010
Accepted 4 March 2010
Available online 18 March 2010
Keywords:
PTA
Phosphane
Gold
Complex
Water soluble
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
water solubility (236 g/L for PTA) [6] and their low sensitivity to-
wards oxidation [7] (Scheme 1).
Since the early days of classical chemistry, water has been a
common solvent and ligand in many organic and inorganic reac-
tions. As chemistry evolved, new reactions, transformations, com-
plexes and ligands were discovered that required completely
anhydrous conditions as well as special techniques to keep water
out of the reaction [1]. These new methods provided access to a
plethora of new, innovative reactions and transformations and
have enlarged the line-up of accessible compounds considerably.
In recent years, water has been experiencing a renaissance as a
reaction medium. It was found that the aqueous medium can
enhance known (catalytic) reactions and transformations dramat-
ically [2–4]. To utilize known and to discover new advantages of
water as a reaction medium comprehensively, new water soluble
and water stable transition metal complexes need to be provided.
One of the most commonly applied phosphane ligands in the
synthesis of water soluble transition metal complexes is the
monodentate cage-like 1,3,5-triaza-7-phosphaadamantane (PTA)
1 and its monoalkylated ammonia salt derivatives (2) [5]. The
advantage of this unique class of ligands is their inherently high
PTA was first reported in 1974 by Daigle et al. [8]. Although the
coordination chemistry of many different transition metal com-
plexes with PTA as a ligand have been studied in details [5,9–15],
surprisingly the preparation and application of the corresponding
PTA ammonia salts have experienced only little attention over a
long period of time. In the first publication documenting the syn-
thesis of PTA it was already pointed out that PTA reacts readily
with alkyl halogenides to afford N-alkylated quarternary ammonia
salts [8]. In order to increase the water solubility of PTA derivatives
and the corresponding transition metal complexes, the issue of
providing new variously substituted N-alkylated PTA derivatives
was resumed to establish the grounds for new synthetic routes
in the modification of the adamantanoid framework. So far PTA
has been derivatized to some differently N-monoalkylated ammo-
nia salts. The most commonly compounds found were synthesized
by reacting PTA with benzylchloride [16], MeI [17,18], EtI [19], nPrI
[20], nBuI [21], I(CH2)4I [22], MeOSO2CF3 [23] and C5H4NCH2Br [24]
to furnish the mono-N-alkylated compounds.
In the recent past PTA and its derivatives have found their way
into catalysis [21,25], underlining the importance of this class of
compounds.
Besides a rich coordination chemistry of many transition metals
[5,15,21,26], only a few gold complexes using PTA salts as ligands
* Corresponding author. Tel./fax: +44 29 2087 6968.
E-mail address: schafers@cf.ac.uk (S. Schäfer).
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.03.012

1926
S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
(10 mL). The aqueous phase was extracted two times with DCM.
After evaporation of the solvent, 6 was obtained as a colorless oil
P
P
N
X
~
N
(957 mg, 4.31 mmol, 97%). IR (neat):
m
= 1765, 1411, 1200, 1138,
N
N
N
R
1028, 810, 610, 494, 238 cmÀ1
.
1H NMR (400 MHz, CDCl3, 25 °C):
N
d = 3.86 (s, 3H, COOMe), 4.92 (s, 2H, TfOCH2COOMe) ppm. 13C
NMR (101 MHz, CDCl3, 25 °C): d = 53.2 (COOMe), 68.8 (TfOCH2-
COOMe), 118.4 (JF,C = 319.5 Hz, CF3), 164.9 (COOMe). 19F NMR
(176 MHz, CDCl3, 25 °C): d = À74.61 ppm. MALDIÀ MS: m/z = 149
[TfO]À. MS: (EI+, 70 eV): m/z = 221 (1) [MÀH]+, 99 (18), 79 (51),
69 (100), 59 (51). Anal. Calc. C4H5F3O5S (222.1): C, 21.63; H, 2.27.
Found: C, 21.11; H, 2.66%. HRMS: (CI+, reaction gas: CH4): Calc.
for C4H6F3O5S: 222.9883. Found: 222.9864.
PTA
PTAR R = alkyl, benzyl,..
1
2
X = I, Br, Cl, TfO,..
Scheme 1. PTA 1 and N-monosubstituted derivatives 2.
have been reported so far [19,20,27–29]. Herein we present new
routes and transformations to gain access to new N-alkylated
PTA derivates and their application as ligands for gold(I) com-
plexes. The water solubility of the newly synthesized PTA deriva-
tives and their gold(I) complexes were investigated as well.
2.2.2. 1-Methoxycarbonylmethyl-3,5-diaza-1-azonia-7-
phosphatricyclo[3.3.1.13,7]decane bromide [PTACH2CO2Me]Br (8)
2. Experimental
P
Br
2.1. General methods, materials and measurements
MeO2C
N
N
N
NMR spectra were recorded on Bruker ARX 300, ARX 400, ARX
500 and ARX 600 spectrometers. 1H NMR spectra were measured
at 300, 400, 500 and 600 MHz; 13C{1H} NMR spectra were recorded
at 101 and 126 MHz. Chemical shifts are quoted relative to residual
solvent peaks. 31P{1H} NMR spectra were measured at 203 and
162 MHz. Chemical shifts are quoted relative to an external
H3PO4 standard. 19F{1H} NMR spectra were collected at 176 MHz
with chemical shifts quoted to an external CFCl3 standard. Cou-
pling constants, J, are given in Hz. Multiplicity as follows: s = sin-
glet, d = doublet, t = triplet, q = quartet, m = multiplet, b = broad
signal. Proton- and carbon-assignment was achieved using H,H
and C,H correlation spectra, and HMBC spectra. Mass spectra were
measured on a MALDI-TOF Microflex [Laser N2 (337 nm 3.57 eV);
Matrix: DHB or DIT], Finnigan MAT 90, Bruker Daltonics micrO-
TOF-Q, Varian 711 and Bruker Daltonics FLEX-PC. IR spectra were
recorded on Perkin–Elmer 100 and Bruker Vector 22 spectrome-
ters. Elemental analyses were obtained by using a Perkin–Elmer
240 B, Perkin–Elmer 2400 B and Carlo Erba Strumentazione Ele-
mental Analyser 1106. Melting points were measured on a Fish-
er-Johns Melting Point Apparatus Kofler and Büchi SMP 20 and
are uncorrected. Chemicals were purchased from Aldrich, Lancas-
ter and Fluka and were used without further purification. Diethyl-
ether (Et2O) and tetrahydrofuran (THF) were dried over sodium/
benzophenone and distilled prior to use. Acetone and dichloro-
methane (DCM) were dried over CaH2 and distilled prior to use.
Dry methanol (MeOH) was purchased from Fluka and used without
further purification. The reactions requiring the exclusion of air
were carried out under an atmosphere of argon or nitrogen in oven
dried glassware using standard Schlenk techniques.
Under an atmosphere of argon, using standard Schlenk techniques,
methyl bromoacetate (76.5 mg, 500 mol) in acetone (10 mL) was
added dropwise to a mixture of PTA (78.6 mg, 500 mol) in acetone
l
l
(10 mL) at 0 °C. After the addition was complete, the mixture was
stirred for an additional 25 min at 0 °C. The reaction mixture was
then allowed to warm up to room temperature and Et2O (10 mL)
was added to complete precipitation. After filtration, washing with
Et2O and drying in vacuo, 8 was obtained as a colorless solid
~
(147 mg, 472 lmol, 94%). M.p.: 148–150 °C. IR (neat): m = 2907,
1742, 1451, 1220, 1029, 983, 909, 807, 757, 742, 552, 439, 395,
353, 258 cmÀ1 1H NMR (500 MHz, [D4] methanol, 25 °C): d = 3.35
.
(s, 3H, COOMe), 3.86 (s, 2H, N+CH2COOMe), 3.94–4.08 (m, 4H,
NCH2P), 4.53 (dt, JH,H = 13.6 Hz, 1.7 Hz, 1H, NCH2aN), 4.64–4.69 (m,
3H, NCH2bN, N+CH2P), 5.05 (d, JH,H = 11.1 Hz, 2H, N+CH2aN), 5.31–
5.39 (m, 2H, N+CH2bN), ppm. 13C NMR (126 MHz, [D4] methanol,
25 °C): d = 47.7 (JP,C = 21.2 Hz, 2C, NCH2P), 50.0 (N+CH2COOMe),
53.9 (N+CH2COOMe), 55.4 (JP,C = 35.0 Hz, N+CH2P), 71.5 (NCH2N),
82.3 (2C, N+CH2N), 166.1 (COOMe) ppm. 31P{1H} NMR (162 MHz,
[D4] methanol, 25 °C): d = À82.33 ppm. MALDI+ MS: m/z = 230
[M]+, 187 [MÀC2H5N]+, 129 [MÀC4H7NO2]+. ESI+ MS: m/z (%): 230
(12) [M]+, 218 (51), 189 (15), 175 (100), 158 (7), 146 (68), 129
[MÀC4H7NO2]+ (9), 117 (6). Anal. Calc. for C9H17BrN3O2P (310.1):
C, 34.86; H, 5.53; N, 13.55. Found: C, 34.23; H, 5.56; N, 13.33%.
HRMS (ESI+): Calc. for C9H17N3O2P: 230.1053. Found: 230.1040.
2.2.3. 1-Methoxycarbonylmethyl-3,5-diaza-1-azonia-7-
phosphatricyclo[3.3.1.13,7]decane triflate [PTACH2CO2Me]OTf (9)
2.2. Synthesis of the compounds
P
2.2.1. (methoxycarbonyl)methyltrifluoromethane sulfonate [30] (6)
OTf
MeO2C
N
N
N
TfO
CO2Me
Under an atmosphere of argon, using standard Schlenk techniques,
(methoxycarbonyl)methyltrifluoromethane sulfonate (111 mg, 500
Under an atmosphere of argon, using standard Schlenk techniques,
trifluoromethanesulfonic anhydride (1.44 g, 5.10 mmol) was added
dropwise to a mixture of methyl glycolate (7) (400 mg, 4.44 mmol)
and pyridine (456 mg, 5.78 mmol) in DCM (8 mL) at À78 °C. After
the addition was complete, the mixture was stirred for an addi-
tional 35 min at À78 °C. The reaction mixture was then allowed
to warm up to room temperature and stirred for further 3 h. The
reaction was quenched by adding water (10 mL) and DCM
lmol) in acetone (10 mL) was added dropwise to a mixture of PTA
(78.6 mg, 500 mol) in acetone (10 mL) at 0 °C. After the addition
l
was complete, the mixture was stirred for an additional 35 min at
0 °C. The reaction mixturewas thenallowed towarm up to room tem-
perature and Et2O (10 mL) was added to complete precipitation. After
filtration, washing with Et2O and drying invacuo, 9 was obtained as a
colorless solid (165 mg, 435 lmol, 87%). After recrystallization from

S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
1927
water, single crystals suitable X-ray diffraction were obtained. M.p.:
added dropwise to a mixture of PTA (157 mg, 1.0 mmol) in acetone
(10 mL) at À45 °C over a period of 1.5 h. After the addition was
complete, the mixture was stirred for an additional 1.5 h at
À45 °C. The reaction mixture was then allowed to warm up to room
temperature and Et2O (10 mL) was added to complete precipitation.
After filtration, washing with Et2O and drying in vacuo, 11 was ob-
~
m
119–121 °C. IR (neat):
= 2963, 1760, 1457, 1254, 1213, 1154, 1025,
907, 804, 754, 572, 517, 347, 253 cmÀ1. 1H NMR (400 MHz, [D6] ace-
tone, 25 °C): d = 3.82 (s, 3H, COOMe), 4.11 (s, 2H, N+CH2COOMe), 4.12
(d, JP,H = 10.5 Hz, 4H, NCH2P), 4.63 (d, JH,H = 13.6 Hz, 1H, NCH2aN),
4.74 (dt, JH,H = 13.5 Hz, 1.7 Hz, 1H, NCH2bN), 4.84 (d, JP,H = 6.0 Hz,
2H, N+CH2P), 5.28 (d, JH,H = 11.5 Hz, 2H, N+CH2aN), 5.49–5.57 (m,
2H, N+CH2bN) ppm. 13C NMR (125.8 MHz, [D4] methanol, 25 °C):
d = 47.7 (JP,C = 21.2 Hz, 2C, NCH2P), 50.1 (N+CH2COOMe), 53.9
(N+CH2COOMe), 55.4 (JP,C = 34.9 Hz, N+CH2P), 71.5 (NCH2N), 82.4
(2C, N+CH2N), 122.0 (JF,C = 318.2 Hz, CF3), 166.1 (COOMe) ppm.
31P{1H} NMR (162 MHz, [D6] acetone, 25 °C): d = À82.14 ppm. 19F
NMR (176 MHz, [D6] acetone, 25 °C): d = À80.29 ppm. MALDI+ MS:
m/z = 230 [M]+, 187 [MÀC2H5N]+, 129 [MÀC4H7NO2]+. MALDIÀ MS:
m/z = 149 [M]À. ESI+ MS: m/z = 230 (100) [M]+, 187 (90) [MÀC2H5N]+,
175 (14), 146 (10), 129 [MÀC4H7NO2]+, 100 (6). Anal. Calc. for
C10H17F3N3O5PS (379.3): C, 31.67; H, 4.52; N, 11.08. Found: C,
31.28; H, 4.57; N, 10.76%. HRMS (ESI+): Calc. for C9H17N3O2P:
230.1053. Found: 230.1046.
tained as a colorless solid (224 mg, 810
l
mol, 81%). Decomp. p.:
~
165 °C. IR (neat):
m
= 2962, 2871, 1414, 1313, 1224, 1125, 1090,
1027, 984, 957, 913, 904, 803, 750, 731, 545, 396, 378, 305 cmÀ1
.
1H NMR (400 MHz, [D4] methanol, 25 °C): d = 3.85–4.10 (m, 6H,
NCH2P, N+CH2CN), 4.52 (dt, JH,H = 13.7 Hz, 1.9 Hz, 1H, NCH2aN),
4.58–4.64 (m, 2H, N+CH2P), 4.68 (dt, JH,H = 13.8 Hz, 1.9 Hz, 1H,
NCH2bN), 5.12 (d, JH,H = 10.9 Hz, 2H, N+CH2aN), 5.21–5.27 (m, 2H,
N+CH2bN) ppm. 31P{1H} NMR (162 MHz, [D4] methanol, 25 °C):
d = À80.74 ppm. MALDI+ MS: m/z = 197 [M]+. ESI+ MS: m/z = 197
(100) [M]+, 185 (11), 175 (13), 159 (12), 154 (62) [MÀC2H5N]+,
142 (36) [MÀC2H3N2]+, 113 (9). HRMS (ESI+): Calc. for C8H14N4P:
197.0951. Found: 197.0952.
2.2.6. 1-Methoxycarbonylmethyl-3,5-diaza-1-azonia-7-
phosphatricyclo[3.3À.1.13,7]decane tetrafluoroborate
[PTACH2CO2Me]BF4 (12)
2.2.4. 1-Benzyl-3,5-diaza-1-azonia-7-phospha-
tricyclo[3.3.1.13,7]decane bromide [PTAbenzyl]Br (10)
P
P
Br
BF4
Ph
N
N
N
MeO2C
N
N
N
Under an atmosphere of argon, using standard Schlenk techniques,
benzyl bromide (85.5 mg, 500 mol) in acetone (10 mL) was added
dropwise to a mixture of PTA (78.6 mg, 500 mol) in acetone
Under an atmosphere of argon, using standard Schlenk techniques,
methylbromoacetate (153 mg, 1.0 mmol) in acetone (5 mL) and
MeOH (5 mL) was added dropwise to a mixture of PTA (157 mg,
1.0 mmol) and NaBF4 (110 mg, 1.0 mmol) in acetone (5 mL) and
MeOH (5 mL) at 0 °C. After the addition was complete, the mixture
was stirred for an additional 25 min at 0 °C. The reaction mixture
was then allowed to warm up to room temperature. After filtration,
washing with Et2O and drying in vacuo, 12 was obtained as a color-
l
l
(10 mL) at 0 °C. After the addition was complete, the mixture was
stirred for an additional 25 min at 0 °C. The reaction mixture was
then allowed to warm up to room temperature and Et2O (10 mL)
was added to complete precipitation. After filtration, washing with
Et2O and drying in vacuo, 10 was obtained as a colorless solid
~
(146 mg, 445 lmol, 89%). Decomp. p.: 170 °C. IR (neat): m = 2907,
less solid (32.0 mg, 10.1 lmol, 10%).
1454, 1312, 1216, 1126, 1066, 1032, 976, 895, 803, 756, 730, 701,
554, 439, 396, 246 cmÀ1 1H NMR (400 MHz, [D4] methanol,
.
25 °C): d = 3.79–3.89 (m, 2H, NCH2P), 3.91–4.01 (m, 2H, NCH2P),
4.15 (s, 2H, N+CH2Ph), 4.27 (d, JP,H = 6.5 Hz, 2H, N+CH2P), 4.46 (dt,
JH,H = 13.6 Hz, 1.7 Hz, 1H, NCH2aN), 4.64 (dt, JH,H = 13.6 Hz, 1.9 Hz,
1H, NCH2bN), 4.95 (d, JH,H = 11.7 Hz, 2H, N+CH2aN), 5.03 (d,
JH,H = 11.2 Hz, 2H, N+CH2bN), 7.52–7.60 (m, 5H, PhH) ppm. 13C
NMR (101 MHz, [D4] methanol, 25 °C): d = 47.5 (JP,C = 21.2 Hz, 2C,
NCH2P), 54.1 (JP,C = 34.5 Hz, N+CH2P), 67.2 (N+CH2Ph), 71.4 (NCH2N),
81.0 (2C, N+CH2N), 126.7 (PhC), 130.5 (2C, PhC), 131.9 (PhC), 134.1
(2C, PhC) ppm. 31P{1H} NMR (162 MHz, [D4] methanol, 25 °C):
d = À81.48 ppm. ESI+ MS: m/z (%): 248 (100) [M]+, 230 (17), 205
(17) [MÀCH4N2]+, 187 (18), 134 (45), 129 (17) [MÀC8H9N]+. Anal.
Calc. for C13H19BrN3P (327.1): C, 47.58; H, 5.84; N, 12.80. Found:
C, 47.18; H, 5.67; N, 12.76%. HRMS (ESI+): Calc. for C13H19N3P:
248.1311. Found: 248.1306.
2.3. Alternative preparation
Under an atmosphere of nitrogen, using standard Schlenk
techniques, 8 (24.4 mg, 78.9 lmol) and NaBF4 (8.68 mg, 78.9 lmol)
were dissolved in MeOH (1.75 mL) and acetone (2.5 mL). The
mixture was heated to 40 °C for 2 h, cooled to 0 °C, carefully
concentrated under reduced pressure and stored at À28 °C over
night. The formed colorless precipitate was filtered off. The
remaining solvent in the filtrate was removed under reduced
pressure. Drying in vacuo yielded 12 as a colorless solid (11.2 mg,
35.3
M.p.: 137–139 °C. IR (neat):
1051, 1028, 980, 910, 805, 739, 552, 520, 441, 349, 242,
233 cmÀ1 1H NMR (400 MHz, [D4] methanol, 25 °C): d = 3.35 (s,
lmol, 45%).
~
m
= 2950, 1745, 1453, 1429, 1224,
.
3H, COOMe) 3.85 (s, 2H, N+CH2COOMe), 3.85–4.10 (m, 4H, NCH2P),
4.51 (dt, JH,H = 13.7 Hz, 1.7 Hz, 1H, NCH2aN), 4.63 (d, JP,H = 5.4 Hz,
2H, N+CH2P), 4.66 (dt, JH,H = 13.7 Hz, 1.7 Hz, 1H, NCH2bN), 5.03 (d,
JH,H = 10.9 Hz, 2H, N+CH2aN), 5.29–5.36 (m, 2H, N+CH2bN) ppm.
31P{1H} NMR (162 MHz, [D4] methanol, 25 °C): d = À82.37 ppm.
19F NMR (176 MHz, [D4] methanol, 25 °C): d = À154.07 ppm. MAL-
DI+ MS: m/z = 230 [M]+, 187 [MÀC2H5N]+, 129 [MÀC4H7NO2]+.
MALDIÀ MS: m/z = 87 [M]À. ESI+ MS: m/z = 230 (100) [M]+, 187
(91) [MÀC2H5N]+, 175 (8), 129 (15) [MÀC4H7NO2]+, 116 (6), 100
(6). Anal. Calc. for C9H17F4BN3O2P (317.0): C, 34.10; H, 5.40; N,
13.25. Found: C, 34.12; H, 5.41; N, 12.83%. HRMS (ESI+): Calc. for
C9H17N3O2P: 230.1053. Found: 230.1044.
2.2.5. 1-Cyanomethyl-3,5-diaza-1-azonia-7-
phosphatricyclo[3.3.1.13,7]decane bromide [PTACH2CN]Br (11)
P
Br
NC
N
N
N
Under an atmosphere of argon, using standard Schlenk techniques,
bromoacetonitrile (120 mg, 1.0 mmol) in acetone (10 mL) was

1928
S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
2.3.1. 1-Carboxymethyl-3,5-diaza-1-azonia-7-phospha-
Compound 9 (42.3 mg, 132
lmol) was added to a mixture of
tricyclo[3.3.1.13,7]decane bromide [PTACH2CO2H]Br (13)
AuCl(tht) (50.0 mg, 132 mol) in acetone (4 mL) at room tempera-
l
ture. The mixture was stirred for 8 h at room temperature. After
addition of Et2O (5 mL), filtration, washing with Et2O and drying
P
in vacuo, 16 was obtained as a colorless solid (60.9 mg, 99.6
l
mol,
~
76%). Decomp. p.: 145 °C. IR (neat):
m
= 3490, 2986, 1745, 1453,
Br
HO2C
N
N
N
1246, 1223, 1160, 1026, 985, 808, 735, 635, 574, 516, 318,
246 cmÀ1 1H NMR (400 MHz, [D4] methanol, 25 °C): d = 3.88 (s,
.
3H, COOMe), 4.07 (d, JH,H = 2.1 Hz, 2H, N+CH2COOMe), 4.35–4.55
(m, 5H, NCH2P, NCH2aN), 4.70 (d, JH,H = 13.9 Hz, 1H, NCH2bN), 5.02
(d, JP,H = 5.6 Hz, 2H, N+CH2P), 5.10 (d, JH,H = 11.6 Hz, 2H, N+CH2aN),
5.47 (d, JH,H = 10.9 Hz, 2H, N+CH2bN) ppm. 31P{1H} NMR (162 MHz,
[D4] methanol, 25 °C): d = À31.58 ppm. 19F NMR (176 MHz, [D4]
methanol, 25 °C): d = À80.35 ppm. ESI+ MS: m/z = 863 (43), 689
(11), 675 (6) [M+2Na+TfO+Cl+H2O]+, 631 (100), 530 (8), 501 (21),
462 (5) [M+Cl]+, 407 (2). Anal. Calc. for C10H17AuClF3N3O6PS
(611.7): C, 19.63; H, 2.80; N, 6.87. Found: C, 19.26; H, 3.00; N,
6.60%. HRMS (ESI+): Calc. for C9H17AuClN3O2P: 462.0407. Found:
462.0383.
Under an atmosphere of argon, using standard Schlenk techniques,
8 (100 mg, 322 mol) was added to a mixture of NaOH (12.9 mg,
322 mol) in Et2O (20 mL) at room temperature. The mixture was
stirred for 3 days at room temperature. After filtration, washing
with Et2O and drying in vacuo, 13 was obtained as a colorless solid
l
l
~
m
(84.1 mg, 154
lmol, 48%). Decomp. p.: 190 °C. IR (neat):
= 3430,
2944, 1609, 1439, 1397, 1221, 1154, 981, 904, 811, 752, 687, 553,
499, 436, 396, 263, 258, 245, 238 cmÀ1 1H NMR (400 MHz, D2O,
.
25 °C): d = 3.52 (s, 2H, CH2COOH), 3.85–4.09 (m, 4H, NCH2P,), 4.47
(dt, JH,H = 13.6 Hz, 1.9 Hz, 1H, NCH2aN), 4.58–4.64 (m, 3H, NCH2bN,
N+CH2P), 4.94 (d, JH,H = 11.2 Hz, 2H, N+CH2aN), 5.20–5.38 (m, 2H,
N+CH2bN) ppm. (s, 1H, CHCOOH) was not detected, possibly being
under the water signal at 4.79 ppm. 31P{1H} NMR (162 MHz, [D4]
methanol, 25 °C): d = À84.04 ppm. ESI+ MS: m/z = 238 (100)
[MÀH+Na]+, 195 (9), 175 (7), 146 (5), 124 (8). HRMS (ESI+): Calc.
for C8H14N3NaO2P: 238.0716. Found: 238.0707.
2.3.4. (1-Benzyl-3,5-diaza-1-azonia-7-phospha-
tricyclo[3.3.1.13,7]decane-P)gold(I) bromide chloride
[AuCl(PTAbenzyl)]Br (17)
AuCl
P
2.3.2. (1-Methoxycarbonylmethyl-3,5-diaza-1-azonia-7-
phosphatricyclo[3.3.1.13,7]decane-P)gold(I) bromide chloride
[AuCl(PTACH2CO2Me)]Br (15)
Br
Ph
N
N
N
AuCl
P
Compound 10 (150 mg, 457
lmol) was added to a mixture of
AuCl(tht) (147 mg, 457 mol) in acetone (15 mL) at room tempera-
l
ture. The mixture was stirred for 14 h at room temperature. After
addition of Et2O (5 mL), filtration, washing with Et2O and drying
Br
MeO2C
N
N
N
in vacuo, 17 was obtained as a colorless solid (178 mg, 318
l
mol,
~
70%). Decomp. p.: 145 °C. IR (neat):
m
= 2960, 1454, 1308, 1121,
1031, 988, 924, 897, 816, 757, 731, 701, 580 cmÀ1
.
1H NMR
Compound 8 (50.0 mg, 161
l
mol) was added to a mixture of
AuCl(tht) (14) (51.7 mg, 161
lmol) in acetone (4 mL) at room tem-
(600 MHz, [D6] DMSO, 25 °C): d = 4.10–4.18 (d, JH,H = 14.8 Hz, 2H,
NCH2P), 4.21–4.31 (m, 4H, NCH2P, N+CH2Ph), 4.34 (d, JH,H = 13.7 Hz,
1H, N+CH2aP), 4.52–4.64 (m, 3H, NCH2N, N+CH2bP), 4.98 (bs, 2H,
N+CH2aN), 5.18 (bs, 2H, N+CH2bN), 7.51–7.61 (m, 5H, PhH) ppm.
31P{1H} NMR (202.5 MHz, [D4] methanol, 25 °C): d = À31.54 ppm.
ESI+ MS: m/z (%): 375 (51), 360 (63) [MÀC9H11]+, 334 (100), 318
(24). HRMS (ESI): Calc. for C4H7AuClN3P: 360.9804. Found:
360.9794.
perature. The mixture was stirred for 2 days at room temperature.
After addition of Et2O (5 mL), filtration, washing with Et2O and dry-
ing in vacuo 15 was obtained as a slightly orange solid (74.1 mg,
~
137 lmol, 85%). Decomp. p.: 170 °C. IR (neat): m = 3368, 2954,
2914, 2498, 2158, 2025, 1976, 1746, 1449, 1309, 1216, 1097,
1029, 985, 901, 808, 737, 544, 436, 388, 354, 315, 279 cmÀ1 1H
.
NMR (400 MHz, [D4] methanol, 25 °C): d = 3.89 (s, 3H, COOMe),
4.15 (d, JH,H = 2.0 Hz, 2H, N+CH2COOMe), 4.44–4.62 (m, 5H, NCH2P,
NCH2aN), 4.72 (d, JH,H = 13.6 Hz, 1H, NCH2bN), 5.10–5.18 (m, 4H,
N+CH2P, N+CH2aN), 5.53 (d, JH,H = 11.5 Hz, 2H, N+CH2bN) ppm.
31P{1H} NMR (162 MHz, [D4] methanol, 25 °C): d = À31.04 ppm.
ESI+ MS: m/z = 707 (3), 631 (25), 594 (85), 592 (14), 562 (92), 560
(100), 518 (80), 516 (32), 505 (11) [M+Br]+, 496 (30), 494 (20),
462 (3) [M+Cl]+, 414 (16), 371 (7). Anal. Calc. for C9H17AuBrClN3O2P
(542.6): C, 19.92; H, 3.16; N, 7.74. Found: C, 19.48; H, 3.50; N, 7.39%.
3. Results and discussions
3.1. Synthesis of N-alkylated PTA salts
The synthesis of the quarternary N-alkylated-PTA compounds
was carried out starting from a suspension of PTA in acetone to
which benzylbromide (3), methyl bromoacetate (4), bromoacetoni-
trile (5) or (methoxycarbonyl)methyltrifluoromethane sulfonate
(6), each dissolved in acetone, was added. Compound 6 was syn-
thesized from the commercially available methyl glycolate (7)
according to a literature procedure [30]. The reactions were carried
out at 0 °C and À45 °C, respectively. After an appropriate reaction
time, the desired monoalkylated ammonia salts were obtained as
colorless solids via precipitation triggered by the addition of a suit-
able amount of diethyl ether. No multiple alkylation was observed.
A polyalkylated PTA salt was not observed, even after refluxing in
acetone with 8 equivalents of bromide or triflate. It has been re-
ported that triflate containing alkylating reagents are able to open
the PTA cage [31]. Using 2 equivalents of 6, even at elevated tem-
2.3.3. (1-Methoxycarbonylmethyl-3,5-diaza-1-azonia-7-
phosphatricyclo[3.3.1.13,7]decane-P)gold(I) chloride triflate
[AuCl(PTACH2CO2Me)]OTf (16)
AuCl
P
OTf
MeO2C
N
N
N

S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
1929
a clear molecular peak. The presence of the triflate anion in com-
pound 9 was proven by means of MALDIÀ MS.
peratures, compound 9 was observed exclusively. In the case of 8
equivalents in refluxing acetone, decomposition of the starting
material was observed.
For the analogous compound to 10 containing chloride as a
counter ion, the chemical shifts in the phosphorus NMR were
found to be at d = À82.2 ppm [7], d = À83.1 ppm [16b] and
d = À86.0 ppm [16a] all recorded with water as the solvent. The
phosphorus NMR of 10 was recorded using [D4] methanol, but
the chemical shift of d = À81.5 ppm is similar. The proton NMR
chemical shifts of 10 (in [D4] methanol) and [PTAbenzyl]Cl (in
water) showed the same order of signals but with a slight high field
R
X
P
P
X
N
R
N
N
N
N
N
acetone
time
temp.
8 11
-
1
shift of around
Dd = 0.15 ppm and only one down field shift of
D
d = 0.10 ppm for the signal of the benzylic protons [16b]. These
minor differences may due to simple solvent effects. The phospho-
rus proton coupling constants of approximately JP,H = 6.4 Hz are
nearly identical.
The water solubility was quantified by the slow addition of
water via a 100 ll syringe to a stirred 100 mg sample of the respec-
The desired compounds 8–11 were isolated in good to excellent
reproducible yields after short reaction times, with high purity con-
firmed by 1H and 31P NMR spectroscopy, and including elemental
analysis for compounds 8, 9 and 10. No further purification of the
reaction products was necessary (Table 1). Due to the higher reac-
tivity of the nitrile compound 5, the reaction had to be carried out
at À45 °C. Performing the reaction at 0 °C resulted in the yield
and purity of the isolated product to be significantly lower (Table
1, entry 4). The obtained products were characterized by 1H NMR,
13C NMR, 31P NMR and IR spectroscopy, mass spectrometry and ele-
mental analysis, and also X-ray diffraction analysis for 9. Signals of
the methylene moieties between a quarternary and tertiary nitro-
gen were detected to be in the range d = 4.90–5.40 ppm (in [D4]
methanol; 8, 10), at d = 5.28 and d = 5.52 ppm (in [D6] acetone; 9)
and at d = 5.12 and d = 5.25 ppm (in [D4] methanol; 11). At
d = 3.86 (8, [D4] methanol) and at d = 4.11 (9, [D6] acetone) ppm,
the methylene moiety adjacent to the quarternary nitrogen and
the ester group was detected. The proton chemical shift of the
methyl ester group was detected at d = 3.35 ppm for 8 in [D4] meth-
anol while d = 3.82 ppm was found for 9 in [D6] acetone. As the an-
ion should not have a larger effect on the chemical shift, the
observed difference seems to be dependant on solvent effects; it
is plausible that methanol is capable of interacting more strongly
with the ester group via hydrogen bonds. The proton signals of
the benzylic moiety of compound 10 were detected at
d = 4.15 ppm. For 11 the chemical shift of NCH2P was found be-
tween d = 3.85 and d = 4.10 ppm (in [D4] methanol). The signals of
the CH2CN moiety were also found in the same range. The solvent
effects seem to play a major role in the chemical shifts in the proton
NMR. The proton-phosphorus coupling constants varied from
JP,H = 10.5 Hz (NCH2P; 9) to 6.0 Hz (N+CH2P; 9) and 6.5 Hz
(N+CH2P; 10). The phosphorus chemical shifts varied only little in
range, d = À81 ppm for all the compounds 8–11, consistent with
findings in the literature for similar compounds [7,16,21,22]. The
carbon–phosphorus coupling constants to the two carbons adjacent
to the tertiary nitrogen were also found to be similar for 8, 9 and 10
(JP,C = 21.2 Hz). Also the coupling constants to the quarternary
nitrogen were in the same range (JP,C = 34.5–35 Hz). In the 19F
NMR spectrum of compound 9, one signal at d = À80.29 ppm was
observed [21]. The carbon–fluorine coupling was determined to
be JC,F = 318.2 Hz. Molecular peaks for the PTA framework were
found in the MALDI+ and in the ESI+ MS spectra for 8, 9 and 11.
Compound 10 was only investigated by ESI+ spectrometry, showing
tive compound at 25 °C. This process was repeated three times.
Studies towards the solubility showed the same values for 9 and
10 (60 g/L) (Table 1, entries 2 and 3), which is lower than the solu-
bility of PTA (236 g/L) [6]. The nitrile substituted compound 11
showed a two times higher water solubility value (123 g/L) com-
pared to 9 and 10 (Table 1, entry 4). The highest value by far was
observed for the ester containing compound 8, with a value of
nearly 1.5 kg/L! It showed a solubility 6 times higher than PTA itself
and this is the highest value for a monoalkylated PTA salt reported
so far. This finding is even more impressive with regards to the fact
that the water solubility of NaBr and NH4Br is 905 g/L and 740 g/L,
respectively [32]. A high value for a PTA derived compound was re-
ported for phenyl-(1,3,5-triaza-7-phosphatricyclo[3.3.1.13,7]dec-6-
yl)methanol (PZA), with a solubility of S20 °C = 1.05 kg/L [33]. The
salt 8 is 1.5 times more soluble in water than the neutral compound
PZA. For comparison of the solubility in water, [PTAbenzyl]Cl was
prepared following a literature procedure [16b]. We found a high
solubility of S25 °C = 700 g/L. The solubility for this compound is
around 11.7 times higher than that of 10, which contains bromide
as the counterion, and half as high as that found for compound 8.
The drawback of chloride containing compounds like [PTAbenzyl]Cl
are the elevated temperatures and longer reaction times necessary
for their preparation. Under the reaction conditions presented here,
benzyl chloride did not react with PTA. Even after 24 h at room tem-
perature no reaction was observed. Interestingly, the solubility de-
pends more on the integrated counterion than on the substituent at
the PTA framework. Introduction of bromide as a counterion re-
sulted in an enhancement of the solubility by a factor of 24 com-
pared to the triflate containing salt. A reason for this difference in
solubility may be found in the huge difference of nucleophilicity
of the counter ions [32,34]. Triflate, as a very weak nucleophile, is
less likely to interact with a polar-protic solvent compared to bro-
mide or chloride. Also separation into ion pairs is less likely for
the triflate containing compound 9.
For a proof of principles, we showed that the counterion could be
exchanged. Already by the reaction of PTA with methyl bromoace-
tate in the presence of just 1 equivalent of NaBF4 (under the same
reaction conditions leading to 9–11) compound 12 was obtained
Table 1
Synthesis of the PTA salts 8–11.
Entry
R
X
Temperature (°C)
t (min)
Compound
Yielda (%)
Solubilityb
1
2
3
4
CO2Me
CO2Me
Ph
Br
OTf
Br
0
0
0
À45
25
35
25
90
8
9
10
11
94
87
89
81
1450
60
60
CN
Br
123
a
Isolated yield.
Solubility in water at 25 °C in g/L.
b

1930
S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
2
4
2
4
4
4
2
2
À
Scheme 2. Synthesis of 12 with BF4 as the anion.
2
2
2
Scheme 3. Synthesis of the carboxylic acid substituted derivative 13.
in 10% yield with BF4À as the counter ion (Scheme 2). The purity was
confirmed by elemental analysis. Alternatively compound 12 could
be synthesized from 8 by an anion exchange reaction in a mixture of
MeOH and acetone. The yield was thereby improved to 45%. One
signal at d = À154.07 ppm was detected in the 19F NMR spectrum.
The remaining product was found to contain a mixture of both an-
ions. The problem of the low yield can be approached by increasing
the amount of added NaBF4 and by fractional crystallization. As it
was shown that the water solubility is heavily dependent on the
counter ion (Table 1), it is important to state that by an exchange
of the counter ion it is possible to tune the solubility properties of
the corresponding compounds. Similar chemical shifts in the 1H
NMR spectrum of 12 were detected, as for 8. The P–H coupling con-
stant for the N+CH2P moiety was determined to be JP,H = 5.4 Hz. The
chemical shift of the phosphorus signal in the 31P NMR spectrum
was similar to 8 (d = À82.37 ppm).
out by replacement of tetrahydrothiophene (tht) from [AuCl(tht)]
(14) by the PTA ammonia salt derivative in acetone at room tem-
perature [35].
AuCl
P
P
AuCl(tht)
X
X
R
N
N
R
N
N
N
N
acetone, r.t.
8-11
15-17
To perform the reaction, 14 was added to a solution of the PTA salt
in acetone and stirred at room temperature under the exclusion of
light for a suitable amount of time. Afterwards Et2O was added to
afford precipitation. Yields between 70% (Table 2, entry 3) and
85% (Table 2, entry 1) were obtained. Unfortunately compound 12
did not form the desired complex. Instead of a colorless solution,
as in the other reactions, a brown suspension was obtained which
indicated the formation of elemental gold. Variations of the reaction
conditions did not lead to the formation of the desired gold com-
plex, on the contrary, the decomposition of the starting material
was always observed.
The gold complexes 15–17 showed comparable chemical shifts
in their 31P NMR spectra, at around d = À31.5 ppm, hardly depend-
ing on the solvent. The complexes 15 and 16 showed changes in
chemical shifts in their 1H NMR spectra compared to the corre-
sponding sole phosphanes. The major difference was found for
the signal of the methyl ester, which was shifted downfield to
approximately d = 3.9 ppm compared to the sole phosphane 8,
and was similar to that found for 9. Also the chemical shift of the
methylene group next to the ester moiety was shifted, with
The transformation of the methylester moiety of compound 8 to
the corresponding carboxylic acid was carried out under basic
conditions in Et2O at room temperature with sodium hydroxide
as a base. The desired compound 13 was obtained in 48% yield
(Scheme 3).
The hygroscopic compound 13 was identified by 1H NMR, 31P
NMR spectroscopy, ESI+ mass spectrometry and HRMS spectrome-
try. The methylene moiety adjacent to the quarternary nitrogen
and the acid group was detected at d = 3.52 ppm. In the 31P NMR
spectrum, one signal was detected at d = À84.04 ppm.
The solubility of 13 in water was determined to be higher
than 8. Because of its highly hygroscopic character, as yet not
enough material has been synthesized to determine an exact
value. Currently, investigations are underway to expand this
general transformation to other PTA and DAPTA derivatives and
to determine their water solubility, as well as investigations to-
wards their potential application as bidentate ligands for transi-
tion metals.
D
d = 0.3 ppm in 15. The complexes 9 and 16 showed almost the
same chemical shift for this moiety (d ꢀ 3.85 ppm). As expected,
proton signals of the methylene units next to the phosphorus atom
were also affected. The shifts were found to be between
3.2. Gold(I) complexes of N-alkylated PTA salts
Dd = 0.45 ppm (for NCH2P) to D
d = 0.5 ppm (for N+CH2P) for
complex 15 compared to 8. Although measured in different sol-
vents, similar effects were observed for 16 compared to 9, and 17
compared to the parental phosphane 10.
The gold(I) complexes [AuCl(PTACH2R)]X (R = CO2Me, phenyl;
X = Br, OTf) are shown in Table 2. The preparation was carried

S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
1931
Table 2
Table 3
Synthesis of the gold(I) complexes 15–17.
Selected bond lengths (Å) and angles (°) for 1-methoxycarbonylmethyl-3,5-diaza-1-
azonia-7-phosphatricyclo[3.3.1.13,7]decane triflate [PTACH2CO2Me]OTf (9).
Entry
R
X
t (h)
Compound
Yielda(%)
Solubilityb
P(1)–C(3)
P(1)–C(4)
P(1)–C(2)
N(2)–C(2)
N(2)–C(4)
N(2)–C(3)
N(1)–C(5)
N(1)–C(2)
N(1)–C(1)
O(1)–C(6)
O(2)–C(6)
O(2)–C(7)
S(1)–O(3)
S(1)–C(8)
C(8)–F(2)
1.577(7)
1.640(5)
1.814(4)
1.425(11)
1.663(17)
1.702(14)
1.490(4)
1.527(3)
1.547(4)
1.197(4)
1.325(4)
1.445(4)
1.434(2)
1.813(4)
1.313(3)
C(3)–P(1)–C(4)
C(3)–P(1)–C(2)
C(4)–P(1)–C(2)
C(2)–N(2)–C(4)
C(2)–N(2)–C(3)
C(4)–N(2)–C(3)
C(5)–N(1)–C(2)
C(5)–N(1)–C(1)
C(2)–N(1)–C(1)
O(1)–C(6)–O(2)
O(4)–S(1)–O(3)
O(4)–S(1)–C(8)
F(2)–C(8)–F(1)
F(2)–C(8)–S(1)
106.6(4)
98.0(2)
96.3(2)
1
2
3
4
CO2Me
CO2Me
Ph
Br
OTf
Br
48
8
14
14
15
16
17
18
85
76
70
48
1.7
4.7
112.9(9)
109.9(8)
100.1(8)
112.47(14)
105.2(2)
108.10(15)
125.2(3)
114.90(11)
103.45(19)
108.3(2)
112.0(2)
CN
Br
a
Isolated yield.
Solubility in water at 25 °C in g/L.
b
~
m
The IR spectra analysis of 15 showed intense bands at
= 3À510
and 320 cmÀ1, and less intensÀe1bands at
= 250 and 230 cm
.
~
m
~
m
The bands at about
= 330 cm are characteÀri1stic for an Au–Cl-
~
m
bond [36,37]. Vibrational bands at
= 240 cm indicate a Au–Br
bond [31,32]. Compound 16, with a triflate counter ion, shows
À1
~
m
the same pattern of bands around
= 240 cm as well, leading
3.3. X-ray structure determination of 1-methoxycarbonylmethyl-3,5-
diaza-1-azonia-7-phosphatricyclo[3.3.1.13,7]decane triflate
[PTACH2CO2Me]OTf (9)
to the assumption that an Au–Cl bond is preferred in the present
gold(I) complexes.
The formation of a gold-complex led to a drastic drop in solu-
bility compared to the sole phosphanes. A comparison of the
water solubility for complexes 15–17 showed the same gradua-
tion as was observed for the parental phosphane ligands. While
the lowest solubility was found for 16 (1.7 g/L, Table 2, entry
2), the highest referred to complex 15 (48 g/L, Table 2, entry 1).
Also the influence of the counter ion was found to be similar.
The solubility of 8 was 24 times higher than that of 9. Compound
15 is 28 times more soluble in water than 16. The water solubility
for compound 17 was determined to be 4.7 g/L, which is slightly
higher than that of 16. However, 15 is more than 10 times more
soluble in water. Compared to the parental phosphanes, the effect
of the counter ion in the gold(I) complexes overcompensates the
substitution effect at the PTA framework, as reflected in the data
of Table 2.
Some gold(I) PTA complexes were found to show possible lumi-
nescent properties [27]. Compounds 15–17 were investigated for
their luminescent properties in the solid state and as an aqueous
solution. Measurements were taken at À20, 0 °C (solid state) and
at room temperature (solid state and solution). The tested com-
pounds showed no luminescence. It has already been stated that
similar compounds like [Au(PTA)]X (X = Cl, Br, I, Me, Ph) and
[Au(H-PTA)]X2 (X = Cl, Br) are not luminescent as aqueous solu-
tions, although [Au(PTA)3]Cl was found to be strongly luminescent
[38].
Single crystals suitable for X-ray diffraction analysis of com-
pound 9 were obtained from water by slow evaporation. The crys-
tal taken for X-ray analysis was
dimensions 1.5 Â 1.0 Â 0.5 mm. Data collection was performed
on a Nicolet P3 with Mo K radiation at 293 K and a wavelength
of 0.71073 Å. The structural refinement was done on F2
a colorless block having
a
(SHELXL97)
[39]. The refinement method referred to full-matrix least-squares
on F2. 3603 reflections were collected with 2506 [Rint = 0.0469] un-
ique ones. The largest diffraction peak and hole were at 0.321 and
À0.271 ÅÀ3. Goodness of fit was determined on F2 1.050 and
F(0 0 0) 784. The h range for data collection was 2.05–30.00°. Com-
pleteness to h = 30.00° was 100.0%. Limiting indices were at
0 6 h 6 18, 0 6 k 6 11 and À21 6 l 6 16. R indices of all data were
found to be R1 = 0.0794 and wR2 = 0.1679. The final R indices
[I > 2
the empirical formula C10H17F3N3O5PS and molecular weight of
M = 379.30 g/mol and
calculated density of 1.565 mg/m3,
r(I)] were R1 = 0.0578 and wR2 = 0.1561. Compound 9, with
a
crystallized as orthorhombic in the asymmetric unit of the centro-
symmetric space group Pnma. The unit cell dimensions are
a = 12.953(2) Å and
c = 15.550(2) Å and
a
c
= 90°, b = 7.9915(15) Å and b = 90° and
= 90° with a cell volume of 1609.6(5) Å3.
Not all molecules showed the same orientation to the anion. Each
of the halves of the molecules in the elementary cell, which
Fig. 1. Thermal ellipsoid representation of 1-methoxycarbonylmethyl-3,5-diaza-1-azonia-7-phosphatricyclo[3.3.1.13,7]decane triflate [PTACH2CO2Me]OTf (9). Thermal
ellipsoids are drawn at the 50% probability level.

1932
S. Schäfer et al. / Polyhedron 29 (2010) 1925–1932
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consists of four cation–anion pairs, showed different orientations
towards each other. The symmetry operator x, 0.5 À y, z completes
the cation and the anion. This symmetry condition forces also a
disorder of the nitrogen N2 and the phosphorus P1. These positions
were changed in the cation, vice versa, characterized by population
factors of 0.5 each. The orientation of the fluorine- and oxygen
atoms of the trifluoromethane sulfonate anion shows, as expected,
a staggered conformation.
The thermal ellipsoid representation of the solid state of com-
pound 9 is shown in Fig. 1. The corresponding selected interatomic
distances and angles are given in Table 3. It is problematical to car-
ry out a quantitative discussion of bond geometries around the dis-
ordered atoms N2 and P1. Some N–C distances are lengthened
(N2–C3, N2–C4) and some P–C distances are shortened (P1–C3,
P1–C4). For example the P1–C3 distance is observed to be
1.577(7) Å, which is about 0.25 Å too short with respect to nominal
aliphatic P–C distances. On the other hand, the N2–C3 distance is
1.70(1) Å which is about 0.25 Å too long compared to nominal 3
covalent N–C distances. This is a result of the disorder, which
‘smears’ the electron density between P1 and N2. (The distance be-
tween P1 and N2 is only 0.4 Å, which is much shorter than the res-
olution of the data (0.7 Å)).
(b) F.-X. Legrand, F. Hapiot, S. Tilloy, A. Guerriero, M. Peruzzini, L. Gonsalvi, E.
Monflier, Appl. Catal. A: Gen. 362 (2009) 62.
4. Conclusion
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2471;
We have presented new routes and transformations at the PTA
framework to gain access to new N-alkylated PTA derivates and
have shown that these compounds can be used as ligands in gold(I)
complexes. An X-ray structure analysis of a new PTA salt has been
presented. The exchange of the counter ion, as well as transforma-
tions at the introduced moiety were successfully performed. Also, a
new class of highly water soluble, possibly bidentate PTA based li-
gands were discovered. Based on these results, the library of water-
soluble phosphane ligands could be expanded and would allow a
straight forward preparation of a series of different metal com-
plexes, permitting the tuning of the electronic properties of the
central metal ion. Studies on the solubility in water discovered
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The next step would be the preparation of PZA salts which should
then lead to compounds that should show even higher solubilities.
The preparation of other PTA salt based gold-complexes and stud-
ies towards their water solubility and their luminescent properties
are currently under way.
(c) P. Servin, R. Laurent, L. Gonsalvi, M. Tristany, M. Peruzzini, J.-P. Majoral, A.-
M. Caminade, J. Chem. Soc., Dalton Trans. (2009) 4432;
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Pombeiro, Inorg. Chim. Acta 362 (2009) 1645;
(e) P. Smolenski, S. Mukhopadhyay, M.F.C. Guedes da Silva, M.A.J. Charmiera,
A.J.L. Pombeiro, J. Chem Soc., Dalton Trans. (2008) 6546.
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5. Supplementary data
CCDC 762475 contains the supplementary crystallographic data
for 9. These data can be obtained free of charge via http://
www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: (+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk
Acknowledgements
The authors thank the Deutscher Akademischer Austausch
Dienst (DAAD) (S.S.) and the Ministerio de Ciencia y Tecnologia
for financial support.
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