Dendritic (phosphine)gold(i) thiolate complexes: Assessment of the molecular size through PGSE NMR studies

Article abstract of DOI:10.1039/b812500g

The reactions of the tetraphosphine ligand DAB-G0-(PPh₂) ₄ (DAB = 1,4-diaminobutane; G0 = Generation 0) or the octaphosphine ligand DAB-G1-(PPh₂)₈ (G1 = Generation 1) with the gold precursor [AuCl(tht)] (tht =te

Full text of DOI:10.1039/b812500g

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www.rsc.org/dalton | Dalton Transactions
Dendritic (phosphine)gold(I) thiolate complexes: assessment of the molecular
size through PGSE NMR studies†
Eduardo J. Ferna´ndez,a Antonio Laguna,b Miguel Monge,*a Manuel Montiel,a M. Elena Olmos,a Javier Pe´reza
and Eva Sa´nchez-Forcadaa
Received 21st July 2008, Accepted 8th September 2008
First published as an Advance Article on the web 12th November 2008
DOI: 10.1039/b812500g
The reactions of the tetraphosphine ligand DAB-G0-(PPh2)4 (DAB = 1,4-diaminobutane; G0 =
Generation 0) or the octaphosphine ligand DAB-G1-(PPh2)8 (G1 = Generation 1) with the gold
precursor [AuCl(tht)] (tht =tetrahydrothiophene) and the corresponding 4-substituted benzenethiolate
lead to the (phosphine)gold(I) thiolate complexes [Au4(S–C6H4–X)4{(DAB-G0-(PPh2)4}] (X = F (11),
MeO (12), Me (13) and NO2 (14)) and [Au8(S–C6H4–X)8{(DAB-G1-(PPh2)4}] (X = F (15), MeO (16),
Me (17) and NO2 (18)). Complexes [Au4Cl4{(DAB-G0-(PPh2)4}] 5 and [Au4(S–C6H4–OMe)4{(DAB-
G0-(PPh2)4}] 12 have been characterized by X-ray diffraction studies showing tetranuclear gold
complexes in which the P–Au–X (X = Cl or S) structural units do not display aurophilic interactions.
PGSE NMR studies of free ligands EN-G0-(PPh2)4 (EN = 1,2-ethylenediamine), DAB-G0-(PPh2)4,
DAB-G1-(PPh2)8 and the (phosphine)gold(I) thiolate complexes permit the evaluation and comparison
of the different molecular sizes depending on the ligand and the dendrimer generation.
“superligands”.8 Among them, polypropylenimine phosphino-
Introduction
terminated dendrimers (DAB-dendr-(PPh2)n) have been described
Polynuclear gold(I) complexes bearing (phosphine)gold(I) thio-
for the synthesis of Pd(II), Ir(I) and Rh(I) homometallic or
late (P–Au–S) structural units have attracted a great deal of
Pd(II)–Ni(II) heterometallic metallodendrimers and their use in
attention in the last years for several reasons.1,2 Most of this
interest arises from the amazing structural dispositions obtained
in the solid state,1 and because some of these complexes dis-
play interesting photoluminescent properties.2 For example, Yam
et al. have recently reported complex [(dppm)2Au4(pipzdtc)]4
(dppm = bis(diphenylphosphino)methane; pipzdtc = piperazine-
1,4-dicarbodithiolate) that consists of a luminescent chiral Au16
closed macrocycle built up through aurophilic interactions be-
tween dinuclear units.3 Also, the medical applications are of inter-
est through the use of the (phosphine)gold(I) thiolate Auranofin
drug and analogues that have been tested for the treatment of
rheumatoid arthritis or as antitumor agents.4
The synthesis of polynuclear (phosphine)gold(I) thiolate com-
plexes is often achieved by the use of bi-,5 tri-6 or tetradentate5g
P-donor ligands. We have recently reported the synthesis of sev-
eral (phosphine)gold(I) 4-substituted benzenethiolate complexes
through the use of a tetraphosphine derived from ethylenediamine
(EN-G0-(PPh2)4) (1) which possesses a pre-dendritic structure.7 In
this sense, one of the main interests of dendritic structures is that
they can be decorated with functional groups at selected locations
as, for example, the periphery, leading to supramolecular species
of well controlled nanometric size that can act as multidentate
homogeneous catalysis.9 Gold(I) metallodendrimers based on
phosphino-terminated dendrimers have also been reported by
Schmidbaur et al.,10 Rossell et al. and Majoral et al.11
There is also a growing interest in the evaluation of molec-
ular size due to the fast development of research devoted to
the synthesis of nanometric molecular entities with particular
properties. There are several techniques that permit the evaluation
of dendrimer size such as, for example, Small Angle Neutron
Scattering (SANS),12 Small Angle X-ray Scattering (SAXS),13
viscosimetry,12 mass spectrometry,14 etc. and, even, theoretical
molecular dynamics simulations.12
A very useful and accessible technique is PGSE-NMR (Pulsed
Field Gradient Spin Echo-Nuclear Magnetic Resonance)15 that
has become the method of choice for measuring the molecular
diffusion in solution that is related to the molecular size through
the Stokes-Einstein equation.
To date, the use of multidentate di-, tri- or tetraphosphine lig-
ands has allowed the synthesis of polynuclear (phosphine)gold(I)
thiolate complexes but higher denticities remain almost unex-
plored. In this sense, phosphino-terminated polypropylenimine
dendrimers (DAB-G1-(PPh2)8) (3) appear as good candidates for
the synthesis of first generation gold(I) metallodendrimers bearing
(phosphine)gold(I) thiolate units at their periphery, leading to
octanuclear complexes.
Herein we report on the synthesis and characterization of new
dendritic-like (phosphine)gold(I) 4-substituted benzenethiolate
complexes derived from the tetradentate phosphorus donor ligand
(DAB-G0-(PPh2)4) = (Ph2PCH2)2N(CH2)4N(CH2PPh2)2 (2) or the
octadentate phosphorus donor dendrimer (DAB-G1-(PPh2)8) =
{(Ph2PCH2)2N(CH2 )3 )2N(CH2 )4N((CH2 )3N(CH2PPh2 )2 }(3)
aDepartamento de Qu´ımica, Universidad de La Rioja, Grupo de S´ıntesis
Qu´ımica de La Rioja, UA-CSIC. Complejo Cient´ıfico-Tecnolo´gico, 26004,
Logron˜o, Spain. E-mail: miguel.monge@unirioja.es; Fax: +34 941 299 621;
Tel: +34 941 299 644
bDepartamento de Qu´ımica Inorga´nica, Instituto de Ciencia de Materiales
de Arago´n, Universidad de Zaragoza-CSIC, 50009, Zaragoza, Spain
† Electronic supplementary information (ESI) available: PGSE-NMR
results. CCDC reference numbers 694723 & 694724. For ESI and crystallo-
graphic data in CIF or other electronic format see DOI: 10.1039/b812500g
474 | Dalton Trans., 2009, 474–480
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©

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(see Fig. 1). We also report the results of Pulsed Field
Gradient Spin Echo (PGSE) NMR studies of dendritic-
like (phosphine)gold(I) thiolate complexes through the use of
the tetradentate phosphorus donor ligand (DAB-G0-(PPh2)4)
or the octadentate phosphorus donor dendrimer (DAB-G1-
(PPh2)8) derived from 1,4-diaminebutane or the first generation
poly(propylenimine) dendrimer DAB-G1-(NH2)4, respectively. We
also compare these complexes with the already reported using the
tetradentate phosphorus donor ligand EN-G0-(PPh2)4 (1) derived
from 1,2-ethylenediamine.7
IR spectra show absorptions arising from the Au–Cl stretching
vibration at 327 and 330 cm-1, respectively.
The synthesis of the pre-dendritic and first generation metallo-
dendrimers with different 4-substituted benzenethiolate ligands is
carried out by reaction of 4 or 8 equivalents of benzenethiolate
ligand, prepared in situ by reaction of the benzenethiols with
an excess of sodium methoxide, and one equivalent of complex
[Au4Cl4{DAB-G0-(PPh2)4}] (5) or [Au8Cl8{DAB-G1-(PPh2)8}]
(6), respectively (see Scheme 1). The corresponding compounds
[Au4(S–C6H4–X)4{DAB-G0-(PPh2)4}] (X = F (11), MeO (12),
Me (13) and NO2 (14)) and [Au8(S–C6H4–X)8{DAB-G1-(PPh2)4}]
(X = F (15), MeO (16), Me (17) and NO2 (18)) are obtained as
1
stable solids. Their 31P{ H} NMR spectra display the shifts for
the corresponding singlets of analogous chemical and magnetic
environment around the P atoms at 23.2, 23.2, 20.0 and 23.2 ppm
for complexes 11–14 and 22.8, 22.9, 22.7 and 24.1 ppm for
complexes 15–18, respectively. Their IR spectra show, in all cases,
the characteristic absorptions due to the n(C–S) stretching at 1104,
878 (11), 1095, 866 (12), 1103, 884 (13) and 1088, 855 cm-1(14) and
1082, 879 (15), 1091, 864 (16), 1082, 866 (17) and 1082, 853 cm-1
(18).
X-Ray structural determination of derivatives 5 and 12
Single crystals suitable for X-ray diffraction studies were ob-
tained by layering diethyl ether into a solution of the complex
in dichloromethane.‡ Both structures consist of tetranuclear
molecules in which each phosphorus atom of the tetradentate
phosphine binds a chlorogold(I) (5) or a thiolategold(I) unit (12)
(see Fig. 2 and 3) with the gold(I) centres displaying their usual
linear environment.
Fig. 1 Tetra- and octadentate phosphine ligands derived from ethylenedi-
amine (1), 1,4-diaminobutane (2) and first generation polypropylenimine
dendrimer derived from 1,4-diaminobutane (3).
˚
The Au–P distances in 5, of 2.233(2) and 2.228(2) A, are nearly
identical to the lower and upper extreme of the Au–P bond
lengths found in a series of dinuclear chlorogold(I) complexes
with functionalized diphosphines, distances which lie in the range
2.227(4)–2.238(4) A (average 2.233(4) A).16 In agreement with the
˚
˚
Results and discussion
lower trans influence of chloride if compared to thiolate ligands,
Synthesis and characterization
˚
the Au–P bond distances in 12 (2.2580(11) and 2.2661(11) A) are
longer than in 5 and similar to those observed in other thiolate
gold(I) complexes with diphosphine2c,5a,17,18 or tetraphosphine7
bridging ligands, lying within the range of the Au–P distances
The multidentate P-donor ligands DAB-G0-(PPh2)4 (2) and
DAB-G1-(PPh2)8 (3) were prepared using a previously reported
strategy.9 Addition of 1,4-diaminobutane or the first generation
poly(propylenimine) dendrimer DAB-G1-(NH2)4 to the phos-
phine Ph2PCH2OH (2 equiv. of phosphine/NH2 group) gives rise
to the P-donor ligands DAB-G0-(PPh2)4 (2) and DAB-G1-(PPh2)8
(3).
=
found in [(Ph2P–R–PPh2){AuSC(OMe) NC6H4NO2-4}2] (R =
CH2, (CH2)2, (CH2)3, (CH2)4, Fc), ranging from 2.2418(16) to
‡ Crystal data for 5: C56H56Au4Cl4N2P4, monoclinic, P21/n, a = 15.140(2),
◦
3
˚
˚
b = 8.990(1), c = 21.390(4) A, b = 94.42(1) , V = 2902.85(7) A , Mw
=
The synthesis of the tetranuclear [Au4Cl4{DAB-G0-(PPh2)4}]
(5) and the octanuclear [Au8Cl8{DAB-G1-(PPh2)8}] (6) chloro-
gold(I) complexes has been achieved by reaction of four or
eight equivalents of the [AuCl(tht)] (tht = tetrahydrothiophene)
precursor and one equivalent of the tetradentate (2) or octadentate
(3) phosphine ligands (see Scheme 1) leading to complexes 5 and
6 in quantitative yields by displacement of the labile ligand tht.
All analytical and spectroscopic data are in agreement with the
1810.57 Z = 2, m = 10.408 mm-1, 22448 reflections, 2qmax 55.76◦, 6119
unique (Rint = 0.057), R = 0.048, Rw(all data) = 0.130 for 316 parameters,
-3
˚
56 restrictions, S = 1.07, max. Dr = 5.89 e A .Crystal data for 12:
¯
C84H84Au4N2O4P4S4, triclinic, P1, a = 10.1723(5), b = 12.2395(4), c =
17.4731(7) A, a = 70.083(2), b = 74.742(2), g = 79.701(2)◦, V =
˚
˚
1963.70(14) A , Mw = 2225.52 Z = 1, m = 7.687 mm-1, 28826 reflections,
3
2qmax 55.00◦, 8945 unique (Rint = 0.033), R = 0.030, Rw(all data) = 0.064
-3
˚
for 462 parameters, 90 restrictions, S = 1.03, max. Dr = 2.99 e A .Crystal
data of 5 and 12 were measured at -100 ◦C using a Nonius Kappa
CCD diffractometer, Mo-Ka radiation, w and f-scans. The structures
were solved by direct-methods and refined anisotropically on F2 (program
SHELXL-97,24, G. M. Sheldrick, University of Go¨ttingen). Hydrogen
atoms were located in the Fourier map and refined using a riding
model. Absorption correction: multi-scan. CCDC 694723 and 694724
contains the supplementary crystallographic data for this paper. For ESI
and crystallographic data in CIF or other electronic format see DOI:
10.1039/b812500g
1
proposed stoichiometries. The 31P{ H} NMR spectra of these
complexes display a singlet at 17.7 (5) or 17.6 ppm (6), respectively,
showing a large shift downfield with respect to the free ligands. The
different methylene groups present in the phosphine ligand are
1
observed in the H NMR spectra in each case and they are also
shifted downfield if compared to those of the free ligand. Their
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Scheme 1 Synthesis of (phosphine)gold(I) thiolate complexes. PPh2 groups are simplified by P atoms for clarity. The synthesis of complexes 4 and 7–10
was already reported (see ref. 7).
˚
Fig. 3 Mole◦cular structure of complex 12. Selected bond lengths [A]
and angles [ ]:#1 -x + 2, -y + 2, -z + 1. Au(1)–S(1) 2.3018(11),
˚
Fig. 2 ◦Molecular structure of complex 5. Selected bond lengths [A] and
angles [ ]: #1 -x + 1, -y + 2, -z. Au(1)–Cl(1) 2.290(3), Au(2)–Cl(2) 2.277(3),
Au(1)–P(1) 2.233(2), Au(2)–P(2) 2.228(2), Cl(1)–Au(1)–P(1) 175.56(10),
Au(2)–S(2) 2.3083(12), Au(1)–P(1) 2.2580(11), Au(2)–P(2) 2.2661(11),
S(1)–Au(1)–P(1) 177.24(4), S(2)–Au(2)–P(2) 171.56(4). H atoms omitted
for clarity.
Cl(2)–Au(2)–P(2) 179.31(12). H atoms omitted for clarity.
2c
˚
˚
2. 2679(15) A. The Au–Cl bonds in 5, of 2.277(3) and 2.290(3) A,
show typical values for gold(I) complexes, which lie within the
plex [Au4(SC6H4OMe)4{(PPh2CH2)2NCH2CH2N(CH2PPh2)2}]
7
˚
˚
˚
range 2.271(2)–2.325(4) A (average 2.297(3) A), corresponding to
the Au–Cl distances found for the dinuclear chloro diphosphine
gold(I) complexes commented above.16 Regarding the Au–S
(2.313(2) and 2.318(2) A), and are comparable to the Au–
S
distances found in other (diphosphine) gold(I) thiolate
complexes,2c,5a,17,18 lying within the range of Au–S bond lengths
˚
=
bond lengths in 12 (2.3018(11) and 2.3083(12) A), these are
observed in [(Ph2P–R–PPh2){AuSC(OMe) NC6H4NO2-4}2] (R =
2c
˚
only slightly shorter than those observed in the related com-
CH2, (CH2)2, (CH2)3, (CH2)4, Fc) (2.2975(19)–2. 3274(19) A.
476 | Dalton Trans., 2009, 474–480
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None of these crystal structures display either intra- nor inter-
molecular Au ◊ ◊ ◊ Au interactions, which are, in contrast, present
in the related tetraphosphine derivative [Au4(SC6H4OMe)4-
{(PPh2CH2)2NCH2CH2N(CH2PPh2)2}]7 and in many chloro-
gold(I) compounds with bridging diphosphines.
The molecular characteristics of the ligand 3 precursor polypropy-
lenimine dendrimer with a diaminobutane core DAB-G1-(NH2)4
has been previously studied through Small-Angle Neutron Scat-
tering (SANS), viscosimetry and molecular dynamics. The radius
of gyration obtained through SANS measurements and molecular
˚
dynamics calculations are 4.4 and 4.9 A, respectively, meanwhile
12
˚
PGSE NMR measurements on free P-donor ligands and on the
(phosphine)gold(I) thiolate complexes 7–18
the hydrodynamic radius obtained through viscosimetry is 6.1 A.
These previous results are close to the one obtained for the ligand
DAB-G1-(PPh2)8 (3) through PGSE-NMR in which a slightly
larger rH of 7.21 A is achieved.
PGSE experiments were carried out on 5 mm CDCl3 samples
of the free tetraphosphines EN-G0-(PPh2)4 (1), DAB-G0-(PPh2)4
(2) and octaphosphine ligands DAB-G1-(PPh2)8 (3) and on the
corresponding [Au4(S–C6H4–X)4{EN-G0-(PPh2)4}] (X = F (7),
MeO (8), Me (9) and NO2 (10)), [Au4(S–C6H4–X)4{DAB-G0-
(PPh2)4}] (X = F (11), MeO (12), Me (13) and NO2 (14)) and
[Au8(S–C6H4–X)8{DAB-G1-(PPh2)4}] (X = F (15), MeO (16), Me
(17) and NO2 (18)) complexes (see Fig. 4 and Experimental section
for details). With this methodology it is possible to estimate the
self-diffusion coefficient Dt for each compound and, subsequently,
by the use of the Stokes–Einstein equation, the evaluation of
the molecular size through the hydrodynamic radius rH can be
carried out. The results are given in Table 1, including the diffusion
coeficients Dt and hydrodynamic radius rH for the ligands 1–3 and
for the (phosphine)gold(I) thiolate complexes 7–18.
˚
PGSE-NMR experiments performed on (phosphine)gold(I)
thiolate complexes 7–18 derived from ligands 1–3 also display in-
teresting results. The hydrodynamic radius of the metal complexes
depend on two main factors. The first one is the P-donor ligand
and, thus, when ligand EN-G0-(PPh2)4 is used, the rH for the differ-
˚
ent (phosphine)gold(I) thiolate complexes are in the 5.81–6.51 A
range; in the case of DAB-G0-(PPh2)4 ligand the rH obtained for
˚
complexes 11–14 lies between 6.40 and 7.20 A and, finally, the
rH of the first generation metallodendrimers based on DAB-G1-
˚
(PPh2)8 ligand are between 8.03 and 8.70 A. The second factor is
the substituent in position 4 of the benzenethiolate ligands. The
effect is analogous for the three families of Au(I) complexes leading
to smaller hydrodynamic radius when the substituent in 4 position
is a fluoride atom, meanwhile larger rH values are achieved when
a nitro group is used (see Fig. 5). These results are similar to
those previously reported for DAB-rhodium metallodendrimers
DAB-dendr-[NH(O)COCH2CH2OC(O)C5H4Rh-(NBD)]n [n = 4,
8, 16, 32, and 64; NBD = norbornadiene] in which the rH for the
first generation metallodendrimers is between 8.7 and 9.4 A.15b We
˚
have also compared the rH with the crystallographic radius rX-ray
,
that is deduced from X-ray data, by dividing the volume of the
crystallographic cell by the number of molecules and assuming
an spherical shape, for complexes 8 and 12 (see Table 2). The
results obtained through PGSE-NMR measurements are close to
Fig. 4 Sections of 1H-PGSE NMR spectra in CDCl3 for complex 8. The
resonance intensities of CH3–O–, P–CH2–N and N–CH2–CH2–N protons
decrease upon increasing the pulsed-field gradient. (The P–CH2–N signal
is a broad signal without resolved multiplicities.)
The larger Dt coefficients are obtained for the free ligands 1–3
in agreement with their smaller size. The rH value increase slightly
going from EN-G0-(PPh2)4 (1) to DAB-G0-(PPh2)4 (2) due to the
larger diaminobutane core compared to the ethylenediamine one.
Table 1 Diffusion coefficient (¥ 1010 Dt/m2 s-1) and hydrodynamic radius
˚
(rH/A) for P-donor ligands 1–3 and complexes 7–18
Dt
rH
EN-G0-(PPh2)4 1
6.91
6.49
5.20
5.59
5.20
5.33
4.98
5.24
5.13
4.96
4.76
3.78
3.49
3.51
3.38
4.69
5.00
7.21
5.81
6.23
6.09
6.51
6.40
6.64
6.49
7.20
8.03
8.66
8.44
8.70
DAB-G0-(PPh2)4 2
DAB-G1-(PPh2)8 3
Fig.
5
Hydrodynamic radius of complexes 7–18 derived from
[Au4(S–C6H4–F)4{EN-G0-(PPh2)4}] 7
[Au4(S–C6H4–OMe)4{EN-G0-(PPh2)4}] 8
[Au4(S–C6H4–Me)4{EN-G0-(PPh2)4}] 9
[Au4(S–C6H4–NO2)4{EN-G0-(PPh2)4}] 10
[Au4(S–C6H4–F)4{DAB-G0-(PPh2)4}] 11
[Au4(S–C6H4–OMe)4{DAB-G0-(PPh2)4}] 12
[Au4(S–C6H4–Me)4{DAB-G0-(PPh2)4}] 13
[Au4(S–C6H4–NO2)4{DAB-G0-(PPh2)4}] 14
[Au8(S–C6H4–F)8{DAB-G1-(PPh2)4}] 15
[Au8(S–C6H4–OMe)8{DAB-G1-(PPh2)4}] 16
[Au8(S–C6H4–Me)8{DAB-G1-(PPh2)4}] 17
[Au8(S–C6H4–NO2)8{DAB-G1-(PPh2)4}] 18
EN-G0-(PPh2)4 (ꢀ), DAB-G0-(PPh2)4 (●) or DAB-G0-(PPh2)8 (ꢀ).
˚
Table 2 Hydrodynamic radius (rH/A) and molecular radius obtained
˚
from X-ray diffraction studies (rX-ray/A) for complexes 8 and 12
rH
rX-ray
[Au4(S–C6H4–OMe)4{EN-G0-(PPh2)4}] 8
[Au4(S–C6H4–OMe)4{DAB-G0-(PPh2)4}] 12
6.23
6.64
8.14a
7.77
a Complex 8 crystallizes with a toluene molecule.
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©

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the ones obtained through X-ray diffraction experiments. It is also
worth mentioning that the rH for complexes 8 and 12 is smaller
kT
Dt =
(3)
crHhp
than the corresponding rX-ray and this is also in agreement with the
15a
Using the obtained diffusion coefficients Dt of the sample and
the internal standard, and through the Stokes–Einstein equation
(3), an accurate value of the hydrodynamic radius rH can be
obtained in each case.21
upper limit of rH usually being rXray
.
Experimental
General
Synthesis
The compounds [AuCl(tht)],19 DAB-G0-(PPh2)4 and DAB-G1-
9
9
General procedure for the preparation of DAB-G0-(PPh2)4 (2)
and DAB-G1-(PPh2)8 (3). Ph2PH (0.53 g, 2.87 mmol) was
dissolved in dry methanol (10 mL) under inert conditions and
p-formaldehyde (0.09 g, 2.87 mmol) was added to this solution.
After 30 min of stirring at 70 ◦C the reaction mixture was
cooled down and 3 mL of a methanol solution containing the
amine compound NH2(CH2)4NH2 (0.06 g, 0.72 mmol) (2) or
[(NH2CH2CH2CH2 )2NCH2CH2CH2CH2N(CH2CH2CH2NH2 )2 ]
(0.11 g, 0.36 mmol) (3) was added. The reaction mixture was stirred
for 1 h at RT and 15 mL of dry toluene were added. After 12 h of
stirring at room temperature, the reaction mixture was heated at
105 ◦C for 3 h. Evaporation to dryness under vacuum gave rise to
phosphine 2 or 3 as thick viscous oils.
(PPh2)8 were synthesized by standard literature procedures.
The starting materials Ph2PH, p-formaldehyde, NH2CH2CH2-
CH2CH2NH2 and [(NH2CH2CH2CH2)2N(CH2)4N(CH2CH2CH2-
NH2)2] were purchased from Sigma Aldrich and used without
further purification.
Instrumentation
Infrared spectra were recorded in the 4000–200 cm-1 range on
a Nicolet Nexus FT-IR spectrophotometer, using Nujol mulls
between polyethylene sheets. C, H, N analyses were carried
out with a C.E. Instrument EA-1110 CHNS-O microanalyser.
MALDI-TOF spectra were recorded in a Microflex MALDI-TOF
Bruker spectrometer operating in the linear and reflector modes
2: From NH2(CH2)4NH2. Quantitative yield. 1H NMR
(300 MHz, CDCl3) d: 7.35–7.25 [m, 40H, Ph rings], 3.54 [m,
8H, PCH2N], 2.75 [m, 4H, NCH2(CH2)2CH2N], 1.25 [m, 4H,
1
using dithranol as matrix. 31P{ H}, 19F and 1H NMR experiments
were recorded on a Bruker ARX 300. PGSE-NMR experiments
were recorded on a Bruker AVANCE 400 in CDCl3.
1
NCH2CH2CH2CH2N] ppm. 31P{ H} NMR (121 MHz, CDCl3)
d: -28.46 ppm.; MS (MALDI +) m/z (%) = 727 (1) [M + H -
2Ph]+; C56H56N2P4 (880.97) calcd. C 76.35, H 6.41, N 3.18; found
C 76.20, H 6.46, N 3.23%.
PGSE experiments
1H-PGSE measurements were carried out using the double stimu-
lated echo pulse sequence (Double STE)20 on a Bruker AVANCE
400 equipped with a BBI H-BB Z-GRD probe at 298K without
spinning. When this double stimulated echo pulse sequence is
used, the dependence of the resonance intensity I on a constant
waiting time and on a varied gradient strength G is described by the
eqn (1):
3: From [(NH2CH2CH2CH2)2NCH2CH2CH2CH2N(CH2CH2-
CH2NH2)2]. Quantitative yield. 1H NMR (300 MHz, CDCl3) d:
7.40–7.28 [m, 80H, Ph rings], 3.56 [m, 16H, PCH2N], 2.82 [m,
8H, m, CH2NCH2P], 2.35–2.26 [m, 12H, NCH2CH2CH2CH2N
and NCH2CH2CH2NCH2P], 1.51 [m, 12H, NCH2CH2CH2N and
1
NCH2CH2CH2CH2N] ppm.31P{ H} NMR (121 MHz, CDCl3) d:
-28.48 ppm.; MS (MALDI +) m/z (%) = 1444 (67) [M + 5H
- 6Ph]+; C120H128N6P8 (1902.21) calcd. C 75.77, H 6.78, N 4.41;
found C 75.49, H 6.53, N 4.39%.
Ê
Ë
ˆ
d
3
Ê
Ë
ˆ
I = I0 exp -Dt (2pgdG)2 D -
¥104
(1)
Á
˜
¯
Á
˜
¯
where I = intensity of the observed spin-echo, I0 = intensity of the
spin-echo without gradients, Dt = diffusion coefficient, D = delay
between the midpoints of the gradients, d = length of the gradient
pulse, and g = magnetogyric ratio.
General procedure for the preparation of [Au4Cl4{DAB-G0-
(PPh2)4}] (5) and [Au8Cl8{DAB-G1-(PPh2)8}] (6). To a dichloro-
methane solution (20 mL) of [AuCl(tht)] (0.20 g, 0.62 mmol)
was added DAB-G0-(PPh2)4 (2) (0.14 g, 0.15 mmol) or DAB-G1-
(PPh2)8 (3) (0.15 g, 0.08 mmol). After 30 min of stirring at room
temperature, the solvent was evaporated to ca. 5 mL. Addition of
20 mL of n-hexane led to precipitation of compounds 5 and 6.
The pulse sequence was composed of 90◦ pulses. The duration
of the gradients (d) was 2 ms, the delay D was 200 ms and the
strength G was varied during the experiment. The spectra were
acquired using 32 or 64K (K = 1000) points. The exponential plots
of I versus G were fitted using a standard exponential algorithm
implemented in TOPSPIN software.
5: From DAB-G0-(PPh2)4. Quantitative yield, white crys-
talline solid. 1H NMR (300 MHz, CDCl3) d: 7.80–7.20 [m,
40H, aromatic protons], 4.12 [m, 8H, PCH2N], 2.99 [m, 4H,
NCH2CH2CH2CH2N], 1.39 [m, 4H, NCH2CH2CH2CH2N] ppm.
PGSE data were treated21 using CHCl3 as internal standard, and
introducing in the Stokes–Einstein equation (3) the semiempirical
estimation of the c factor, which can be obtained through eqn (2),22
derived from the microfriction theory proposed by Wirtz and co-
workers,23 in which c is expressed as a function of the solute-to-
solvent ratio of the radii.
1
31P{ H} NMR (121 MHz, CDCl3) d: 17.7 ppm. IR: n = 1584
n(C–N), 327 n(Au–Cl) cm-1; MS (MALDI +): m/z (%) = 1264
(12) [M - 2(ClAu) - Ph]+; C56H56Au4Cl4N2P4 (1810.63): calcd. C,
37.15; H, 3.12; N, 1.55; found C, 36.99; H, 3.20; N, 1.52%.
6: From DAB-G1-(PPh2)8. Quantitative yield, white crystalline
solid. 1H NMR (300 MHz, CDCl3) d: 7.77–7.25 [m, 80H, aromatic
protons], 4.12 [m, 16H, PCH2N], 2.98 [m, 8H, CH2NCH2P],
2.14 [m, 12H, NCH2CH2CH2CH2N and NCH2CH2CH2NCH2P],
6
c =
2.234
(2)
Ê
ˆ
¯
r
solv
1 + 0.695
Á
˜
rH
Ë
478 | Dalton Trans., 2009, 474–480
This journal is
The Royal Society of Chemistry 2009
©

View Article Online
1.38 (m, 12H, NCH2CH2CH2N and NCH2CH2CH2CH2N) ppm.
[M - Au3(S–C6H4–NO2)4]+; C80H72Au4N6O8P4S4 (2285.49): calcd.
C, 42.04; H, 3.17; N, 3.68; S, 5.61; found C 41.89; H, 2.97; N, 3.76;
S, 5.52%.
1
31P{ H} NMR (121 MHz, CDCl3) d: 17.6 ppm. IR: n = 1587 n(C–
N), 330 n(Au–Cl) cm-1; MS (MALDI +) m/z (%) = 2829 (45) [M
+ H - 4(ClAu)]+; C120H128Au8Cl8N6P8 (3761.48): calcd. C 38.32; H
3.43; N 2.23; found C 37.93; H 3.28; N 2.01%.
General procedure for the preparation of [Au8(S–C6H4-X)8{DAB-
G1-(PPh2)8}], [X = F, (15); OMe, (16); Me, (17); NO2, (18)].
To a solution of the corresponding benzenethiol (0.425 mmol)
in dichloromethane (20 mL), was added an excess amount of
NaOMe (0.092 g, 1.70 mmol). After 20 min of stirring, complex
[Au8Cl8{DAB-G1-(PPh2)8}] (6) was added (0.20 g, 0.053 mmol).
The reaction mixture was stirred for 2 h, and a white solid (NaCl),
which was separated by filtration, was formed. The filtrate was
evaporated to ca. 5 mL, and addition of diethyl ether (20 mL) led
to precipitation of the compounds.
General procedure for the preparation of [Au4(S–C6H4–
X)4{DAB-G0-(PPh2)4}], [X = F, (11); OMe, (12); Me, (13); NO2,
(14)]. To a dichloromethane solution (20 mL) of benzenethiol
(0.331 mmol), was added an excess amount of NaOMe (0.071 g,
1.32 mmol). After 20 min of stirring, complex [Au4Cl4{DAB-G0-
(PPh2)4}] (5) was added (0.15 g, 0.083 mmol). The reaction mixture
was stirred for 2 h, generating a white solid (NaCl) which was
separated by filtration. The filtrate was evaporated to ca. 5 mL,
and addition of diethyl ether (20 mL) led to precipitation of the
compounds.
15: From 4-fluorobenzenethiol (0.055 g). Yield 63%, pale yellow
1
solid. H NMR (300 MHz, CDCl3) d: 7.70–7.00 [m, 80H, Ph
11: From 4-fluorobenzenethiol (0.042 g). Yield 71%, pale yellow
solid. 1H NMR (300 MHz, CDCl3) d: 7.71–7.40 [m, 40H,
Ph rings], 6.76 [m, 8H, 3-H and 5-H in S–C6H4–F], 4.13 [m,
8H, PCH2N], 3.03 [m, 4H, NCH2(CH2)2CH2N], 1.27 [m, 4H,
rings], 6.71 [m, 16H, 3-H and 5-H in S–C6H4–F], 4.14 [m,
16H, NCH2P], 2.96 [m, 8H, CH2NCH2P], 2.12–2.05 [m, 12H,
NCH2CH2CH2CH2N and NCH2CH2CH2NCH2P], 1.31 [m, 12H,
1
NCH2CH2CH2N and NCH2CH2CH2CH2N] ppm. 31P{ H} NMR
NCH2CH2CH2CH2N] ppm. 31P{ H} NMR (121 MHz, CDCl3)
(121 MHz, CDCl3) d: 22.8 ppm. 19F NMR (283 MHz, CDCl3) d:
-120.70 (s, 8F) ppm. IR: n = 1581 n(C–N); 1082, 879 n(C–S) cm-1;
MS (MALDI +) m/z (%) = 4368 (20) [M - (S–C6H4–F)]+, 4042
(28) [M - Au(S–C6H4–F)2]+, 3717 (40) [M - Au2(S–C6H4–F)3]+;
C168H160Au8F8N6P8S8 (4495.14): calcd. C, 44.89; H, 3.59; N, 1.89;
S, 5.70; found C 44.80; H, 3.29; N, 1.62; S, 6.00%.
1
d: 23.2 ppm. 19F NMR (283 MHz, CDCl3) d: -120.9 [s, 4F] ppm.;
IR: n = 1610 n(C–N); 1104, 878 n(C–S) cm-1; MS (MALDI +)
m/z (%) = 1725 (1) [M - Au(S–C6H4–F)2]+; C80H72Au4F4N2P4S4
(2177.46): calcd. C, 44.13; H, 3.33; N, 1.28; S, 5.89; found C 44.34;
H, 3.40; N, 1.37; S, 5.95%.
12: From 4-methoxybenzenethiol (0.046 g). Yield 45%, yellow
solid. H NMR (300 MHz, CDCl3) d: 7.74–7.39 [m, 40H, Ph
rings], 6.66 [m, 8H, 3-H and 5-H in S–C6H4–OCH3], 4.15 [m, 8H,
16: From 4-methoxybenzenethiol (0.059 g). Yield 62%, yellow
solid. 1H NMR (300 MHz, CDCl3) d: 7.70–7.20 [m, 80H, Ph rings],
6.64 [m, 16H, 3-H and 5-H in S–C6H4–OCH3], 4.18 [m, 16H,
NCH2P], 3.70 [s, 24H, OCH3], 2.96 [m, 8H, CH2NCH2P], 2.16–
2.06 [m, 12H, NCH2CH2CH2CH2N and NCH2CH2CH2NCH2P],
1.32 [m, 12H, NCH2CH2CH2N and NCH2CH2CH2CH2N] ppm.
1
PCH2N], 3.74 [s, 12H, CH3O], 3.00 [m, 4H, NCH2(CH2)2CH2N],
1
1.25 [m, 4H, NCH2CH2CH2CH2N] ppm. 31P{ H} NMR (121
MHz, CDCl3) d: 23.2 ppm. IR: n = 1586 n(C–N); 1169 n(C–O);
1095, 866 n(C–S) cm-1; MS (MALDI +) m/z (%)= 2085 (24) [M -
(S–C6H4–OMe)]+, 1749 (79) [M - Au(S–C6H4–OMe)2]+, 1413 (100)
[M - Au2(S–C6H4–OMe)3]+, 1077 (95) [M - Au3(S–C6H4–OMe)4]+;
C84H84Au4N2O4P4S4 (2225.60): calcd. C, 44.33; H, 3.80; N, 1.25; S,
5.76; found C 44.13; H, 3.76; N, 1.00; S, 5.89%.
1
31P{ H} NMR (121 MHz, CDCl3) d: 22.9 ppm. IR: n = 1587
n(C–N); 1174 n(C–O); 1091, 864 n(C–S) cm-1; MS (MALDI +)
m/z (%) = 4452 (18) [M - (S–C6H4–OMe)]+, 4255 (18) [M + H
- Au(S–C6H4–OMe)]+, 4116 (8) [M - Au(S–C6H4–OMe)2]+, 3779
(18) [M - Au2(S–C6H4–OMe)3]+; C176H184Au8N6O8P8S8 (4591.43):
calcd. C 44.89; H 3.57; N 1.87; S 5.71; found C 45.10; H 3.82;
N1.41; S 5.94%.
13: From 4-methylbenzenethiol (0.041 g). Yield 81%, white
1
solid. H NMR (300 MHz, CDCl3) d: 7.80–7.20 [m, 40H, Ph
rings], 7.40 [m, 8H, 2-H and 6-H in S–C6H4–CH3], 6.87 [m,
8H, 3-H and 5-H in S–C6H4–CH3], 4.10 [s, 8H, PCH2N], 2.95
[s, 4H, NCH2(CH2)2CH2N], 2.21 [s, 12H, Me], 1.29 [m, 4H,
17: From 4-methylbenzenethiol (0.053 g). Yield 68%, white
solid. H NMR (300 MHz, CDCl3) d: 7,70–7.30 [m, 80H, Ph
1
rings], 6.87 [m, 16H, 3-H and 5-H in S–C6H4–CH3], 4.17 [m, 16H,
NCH2P], 2.94 [m, 8H, CH2NCH2P], 2.24 [s, 24H, CH3], 2.17–
2.03 [m, 12H, NCH2CH2CH2CH2N and NCH2CH2CH2NCH2P],
1.33 [m, 12H, NCH2CH2CH2N and NCH2CH2CH2CH2N] ppm.
1
NCH2CH2CH2CH2N] ppm. 31P{ H} NMR (121 MHz, CDCl3)
d: 20.0 ppm. IR: n = 1607 n(C–N); 1103, 884 n(C–S) cm-1 MS
(MALDI +) m/z (%) = 2037 (25) [M - (S–C6H4–Me)]+, 1717 (80)
[M - Au(S–C6H4–Me)2]+, 1397 (100) [M - Au2(S–C6H4–Me)3]+,
1077 (80) [M - Au3(S–C6H4–Me)4]+; C84H84Au4N2P4S4 (2161.60):
calcd. C, 46.67; H, 3.92; N, 1.29; S, 5.93; found C 46.52; H, 3.75;
N, 1.11; S, 5.84%.
1
31P{ H} NMR (121 MHz, CDCl3) d: 22.7 ppm. IR: n = 1587
n(C–N); 1082, 866 n(C–S) cm-1; MS (MALDI +) m/z (%) = 2122
(4) [M + 3H - {(PPh2)4(Au–S–C6H4–Me)5}]+; C176H184Au8N6P8S8
(4463.43): calcd. C 47.36; H 4.15; N 1.88; S 5.74; found C 46.96;
H 3.86; N 1.73; S 5.57%.
14: From 4-nitrobenzenethiol (0.051 g). Yield 89%, orange
1
solid. H NMR (300 MHz, CDCl3) d: 7.90–7.20 [m, 40H, Ph
18: From 4-nitrobenzenethiol (0.066 g). Yield 64%, orange
1
rings], 7.81 [m, 8H, 3-H and 5-H in S–C6H4–CH3], 7.41 [m, 8H,
2-H and 6-H in S–C6H4–CH3], 3.89 [s, 8H, PCH2N], 2.93 [s, 4H,
NCH2(CH2)2CH2N], 1.22 [m, 4H, NCH2CH2CH2CH2N] ppm.
solid. H NMR (300 MHz, CDCl3) d: 7.80–7.25 [m, 80H, Ph
rings], 7.76 [m, 16H, 3-H and 5-H in S–C6H4–NO2], 7.51 [m,
16H, 2-H and 6-H in S–C6H4–NO2], 4.10 [m, 16H, NCH2P], 2.78
[m, 8H, CH2NCH2P], 1.99–1.89 [m, 12H, NCH2CH2CH2CH2N
and NCH2CH2CH2NCH2P], 1.34 [m, 12H, NCH2CH2CH2N and
1
31P{ H} NMR (121 MHz, CDCl3) d: 23.2 ppm. IR: n = 1569 n(C–
N); 1492, 1321 n(C–NO2); 1088, 855 n(C–S) cm-1; MS (MALDI +)
m/z (%) = 2130 (6) [M - (S–C6H4–NO2)]+, 1779 (88) [M - Au(S–
C6H4–NO2)2]+, 1428 (100) [M - Au2(S–C6H4–NO2)3]+, 1077 (97)
1
NCH2CH2CH2CH2N] ppm. 31P { H} NMR (121 MHz, CDCl3)
d: 24.1 ppm. IR: n = 1571 n(C–N); 1496, 1328 n(C–NO2); 1082,
Dalton Trans., 2009, 474–480 | 479
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The Royal Society of Chemistry 2009
©

View Article Online
853 n(C–S) cm-1; MS (MALDI +) m/z (%) = 4557 (12) [M - (S–
C6H4–NO2)]+, 4205 (19) [M - Au(S–C6H4–NO2)2]+, 3855 (40) [M
- Au2(S–C6H4–NO2)3]+; C168H160Au8N14O16P8S8 (4711.20): calcd.
C 42.82; H 3.42; N 4.16; S 5.43; found C 42.70; H 3.28; N 3.97; S
5.45%.
Viotte, B. Gautheron, I. Nifant’ev and L. G. Kuz’mina, Inorg. Chim.
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Conclusions
The use of polydentate dendritic-like phosphines as ligands
has permitted the synthesis of two new families of (phos-
phine)gold(I) thiolate complexes of high nuclearity. The X-ray
diffraction studies of compounds 5 and 12 display tetranuclear
pre-dendritic structures in which each P–Au–X (X = Cl or 4-
methoxybenzenethiolate) structural units appear separated pre-
venting the presence of aurophilic interactions.
PGSE-NMR measurements in solution have permitted the
evaluation of the hydrodynamic radius and, hence, the nanometric
size of these tetra- or octanuclear (phosphine)gold(I) thiolate
compounds showing the influence of the substituent in 4-position
of the benzenethiolate ligands.
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The D.G.I.(MEC)/FEDER (CTQ2007–67273-C02–02) and Eu-
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projects are acknowledged for financial support. E. Sa´nchez-
Forcada thanks the C.S.I.C. for a JAE-Predoc grant. Dr H. Busto
is thanked for fruitful discussions.
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