Synthesis and structural characterization of luminescent gold(I) derivatives with an unsymmetric diphosphine

Article abstract of DOI:10.1039/b309116c

We have synthesised a series of mono-bridged digold(I) derivatives with an unsymmetric diphosphine, namely, [(AuX)₂(μ-PⁱPr₂CH₂ PPh₂)] (X = Cl, Br, I, C₆F₅, S₂CN(CH

Full text of DOI:10.1039/b309116c

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Synthesis and structural characterization of luminescent gold(I)
derivatives with an unsymmetric diphosphine
Manuel Bardají,†a Peter G. Jones,b Antonio Laguna,*a M. Dolores Villacampaa and
Noelia Villaverdea
a Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón,
Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain. E-mail: alaguna@posta.unizar.es;
Fax: ϩ 34 976 761187; Tel: ϩ 34 976 761185
b Institut für Anorganische und Analytische Chemie der Technischen Universität, Postfach 3329,
D-38023 Braunschweig, Germany
Received 31st July 2003, Accepted 17th September 2003
First published as an Advance Article on the web 26th September 2003
We have synthesised a series of mono-bridged digold() derivatives with an unsymmetric diphosphine, namely,
[(AuX)2(µ-PiPr2CH2PPh2)] (X = Cl, Br, I, C6F5, S2CN(CH2Ph)2) and the mononuclear gold() complex
[Au(C6F5)3(PiPr2CH2PPh2)]. X-ray diffraction studies show intramolecular gold()–gold() interactions of 3.4179(2),
3.1660(2) and 3.0926(3) Å, respectively, for X = Cl, Br and C6F5. The pentafluorophenyl derivative emits at 445 nm at
room temperature in the solid state; this compound and the halo-derivatives are emissive at low temperature in the
range 440–486 nm. We have also prepared doubly-bridged diauracycles, namely, [Au2X2(µ-PiPr2CH2PPh2)2] (X = Cl,
Br, I) and [Au2(µ-PiPr2CH2PPh2)2]A2 (A = CF3SO3, ClO4). The crystal structure of the iodo derivative displays three-
coordinated gold centres in a T-shaped geometry, with a gold–gold distance of 2.9931(6) Å and a gold–iodo distance
of 3.0999(6) Å, whilst the triflate derivative displays di-coordinated gold centres and a gold–gold distance of
2.9838(5) Å. All the derivatives are intensely photoluminescent in the visible range, with the emission maxima
between 480 and 513 nm at 298 K and 459–508 nm at 77 K. The emission energies and the gold–gold distances are
not directly related.
X-ray diffraction studies of five derivatives, three mono-bridged
which display gold–gold distances of 3.4179(2), 3.1660(2) and
Introduction
Intramolecular gold()–gold() interactions in the range 2.9–3.6
3.0926(3) Å, respectively, for Cl, Br and C6F5, and two doubly-
Å have been reported in mono- or doubly-bridged dinuclear
bridged with gold–gold distances of 2.9931(6) and 2.9838(5) Å,
complexes. Values from 20 to 50 kJ molϪ1, close to those found
for hydrogen bonds, have been obtained for these gold()–
gold() interactions by analysis of temperature-dependent
respectively for I and CF3SO3.
Results and discussion
NMR measurements. Theoretical studies have suggested corre-
lation effects enhanced by relativistic effects to explain these
aurophilic interactions.1 It has been predicted that the strength
of these contacts should increase with the softness of the
ligand, and this has been confirmed experimentally in some
series of derivatives.2
Since the first report on the photoluminescence of [Au2-
(µ-dppm)2]2ϩ (dppm = bis(diphenylphosphino)methane),3 poly-
nuclear phosphino gold() complexes have received much
attention because they display long-lived emissions in the
visible region, which have been usually attributed to excited
states involving gold–gold bonding.4 However, the intermetallic
separation does not appear to play a significant role in deter-
mining the energy of the emission, whilst the auxiliary ligands,
the counter-ion or the solvent can dramatically affect the
optical properties. In fact, recent studies on [Au2(µ-dcpm)2]2ϩ
(dcpm = bis(dicyclohexylphosphino)methane) point to exci-
plexes to explain the photoluminescence.5
Synthesis and characterization of monobridged derivatives
The reaction of diisopropylphosphine(diphenylphosphine)-
methane with the appropriate gold() complex containing an
easily displaceable ligand, in molar ratio 1 : 2 in dichloro-
methane, leads to the monobridged dinuclear gold() complexes
1–4 (see Scheme 1). Complex 1 reacts with dithiocarbamate
salts to give the corresponding dithiocarbamato derivative 5 by
substitution of the chloro ligands. The reaction of the unsym-
metrical ditertiary phosphine with [Au(C6F5)3(tht)] affords the
mononuclear gold() complex 6. These derivatives are air- and
moisture-stable white (1–4, 6) or yellow (5) solids at room
temperature.
In this work we report the first mono- and doubly-bridged
dinuclear gold() derivatives with an unsymmetric diphosphine,
namely, [(AuX)2(µ-PiPr2CH2PPh2)], [Au2X2(µ-PiPr2CH2PPh2)2]
and [Au2(µ-PiPr2CH2PPh2)2]A2, and also
a mononuclear
gold() derivative. The pentafluorophenyl gold() complex and
all the doubly-bridged diphosphine complexes are intensely
photoluminescent at room and low temperature in the visible
range, whilst most of the other mono-bridged gold() deriv-
atives are only emissive at low temperature. We have carried out
† Present and permanent address: Departamento de Química Inorgá-
nica, Facultad de Ciencias, Universidad de Valladolid, 47005-
Valladolid, Spain.
Scheme 1
T h i s j o u r n a l i s © T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 3
D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
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Table 1 31P{1H} NMR data for monobridged complexes 1–6
Table 2 Selected bond distances (Å) and angles (Њ) within molecules
[(AuX)2(µ-PPh2CH2PiPr2)], X = Cl 1, Br 2, C6F5 4
Complex
δ(PPh2)
δ(PiPr2)
Complex 1
PPh2 CH2PiPr2
Ϫ19.2
39.2
35.4
32.6
37.5
31.1
Ϫ27.5
Ϫ3.9
54.4
51.4
51.6
54.8
54.4
38.4
[(AuCl)2(µ-PiPr2CH2PPh2)]
[(AuBr)2(µ-PiPr2CH2PPh2)]
[(AuI)2(µ-PiPr2CH2PPh2)]
[{Au(C6F5)}2(µ-PiPr2CH2PPh2)]
[{Au(S2CNR2)}2(µ-PiPr2CH2PPh2)]
[Au(C6F5)3(PiPr2CH2PPh2)]
Au(1)–P(1)
Au(1)–Cl(1)
Au(2)–P(2)
Au(2)–Cl(2)
Au(1)–Au(2)
2.2358(7)
2.3008(7)
2.2375(6)
2.2985(6)
3.4179(2)
P(1)–Au(1)–Cl(1)
P(2)–Au(2)–Cl(2)
P(1)–Au(1)–Au(2)
Cl(1)–Au(1)–Au(2)
P(2)–Au(2)–Au(1)
Cl(2)–Au(2)–Au(1)
176.31(2)
175.67(2)
80.818(17)
102.441(17)
73.666(16)
109.136(17)
Complex 2
They were readily characterised by elemental analysis, mass,
IR and NMR spectroscopies (see Experimental section). Their
IR spectra show absorptions at 326 (1) cmϪ1 due to ν(Au–Cl),6
or at 955 and 792 (4) or 966 and 792 (6) cmϪ1 from the penta-
fluorophenyl groups.7 Their acetone solutions are non-conduct-
Au(1)–P(1)
Au(1)–Br(1)
Au(1)–Au(2)
Au(2)–P(2)
Au(2)–Br(2)
2.2445(7)
2.4198(3)
3.1660(2)
2.2403(7)
2.4069(3)
P(1)–Au(1)–Br(1)
P(2)–Au(2)–Br(2)
P(1)–Au(1)–Au(2)
Br(1)–Au(1)–Au(2)
P(2)–Au(2)–Au(1)
Br(2)–Au(2)–Au(1)
175.94(2)
174.08(2)
86.853(19)
93.520(10)
76.759(18)
109.098(10)
1
ing. The H NMR spectra show two doublets of doublets ca.
1.16 and 1.26 ppm for two sets of inequivalent methyl groups,
which are simplified to two doublets in a phosphorus decoupled
experiment; in this experiment a septuplet or a multiplet is
found for the CH of the isopropyl group and a singlet for the
methylene bridge. Two slightly different pentafluorophenyl
groups are seen for complex 4 and a unique Au(C6F5)3 unit for
complex 6.
In the phosphorus NMR spectra an AX spin system is
observed, strongly low-field shifted when the diphosphine is
coordinated (see Table 1). Chemical shifts sequences are differ-
ent, Au(C6F5)3 < AuBr, AuI < AuCl, AuC6F5, AuS2CNR2, for
bis(isopropyl)phosphino group whilst AuS2CNR2 < AuI <
AuBr < AuC6F5 < AuCl is found for diphenylphosphino group,
which is therefore more sensitive to the gold coordinated frag-
ment. The phosphorus NMR spectrum of 6 confirms that the
gold() unit is coordinated to the bis(isopropyl)phosphine
arm; curiously the addition of more gold() precursor does not
lead to the expected dinuclear derivative, as found for dppm
(bis(diphenylphosphino)methane), but complex 6 is recovered
from solution. The mass spectra always show the peak corre-
sponding to the [M Ϫ X]ϩ fragment (X = Cl, Br, I, C6F5,
S2CNR2 and C6F5, respectively, for complexes 1–6).
Complex 4
Au(1)–C(1)
Au(1)–P(1)
Au(1)–Au(2)
Au(2)–C(11)
Au(2)–P(2)
2.044(5)
C(1)–Au(1)–P(1)
C(11)–Au(2)–P(2)
C(1)–Au(1)–Au(2)
P(1)–Au(1)–Au(2)
C(11)–Au(2)–Au(1)
P(2)–Au(2)–Au(1)
175.59(14)
175.70(16)
92.98(14)
91.23(4)
95.54(14)
84.03(4)
2.2682(15)
3.0926(3)
2.046(6)
2.2787(15)
X-Ray crystal structure determination of 1, 2 and 4
The molecular structures of these complexes are similar and
those of complexes 1 and 4 are shown in Figs. 1 and 2, respect-
ively. Selected bonds and angles for complexes 1, 2 and 4 are
summarised in Table 2. Complexes 1 and 2 are not isostruc-
tural; they crystallise with different amounts of solvent. The
molecular structures consist of discrete dinuclear molecules
with an almost linear coordination for the gold() centres, which
is typical of dinuclear dppm gold() derivatives.8 The molecules
display short gold–gold distances, following the sequence: C6F5
< Br < Cl. It is clear in this case that steric hindrance is not
controlling aurophilic interactions (bigger ligands produce
shorter gold–gold distances). Electronic effects have been
Fig. 2 Molecular structure of the dinuclear monobridged derivative 4;
H-atoms are omitted for clarity.
reported to increase aurophilic attractions with the softness of
the ligands, as reported for the series (AuX)2(µ-dpph) (X = Cl, I;
dpph = bis(diphenylphosphino)hexane),2b AuX(TPA) (X = Cl,
Br; TPA = P-(1,3,5-triaza-7-phosphaadamantane)),2c AuX-
(CNxylyl-o) (X = Cl, Br, I, CN),2d [{AuX(PPhMe2)}2] (X = Cl,
Br, I),2e and AuX(PPh2CCH) (X = Cl, I).2f The pentafluoro-
phenyl ligand is quite big and highly electronegative but the
shortest gold–gold distance is displayed. It can be seen in Fig. 2
that pentafluorophenyl rings are almost parallel (angle of 12Њ)
and with a distance of about 3.5 Å and therefore an additional
stabilization could occur by π–π interactions. A similar result
was found in [{Au(C6F5)}2(µ-dppm)], which displays a gold–
gold distance as short as 3.163(1) Å.8e
The Au–P distances display a trans influence in the sequence
Cl < Br < C6F5, for both phosphine arms. The isopropylphos-
phino fragment induces a stronger trans influence compared to
the phenylphosphino fragment over the Au–X distance for X =
Cl, Br, whilst there is no difference for the pentafluorophenyl
derivative. Complexes 1, 2 and 4 display several C–H ؒ ؒ ؒ X
contacts, X = Cl, Br, F or O (solvent), that could be interpreted
as hydrogen bonds. In particular, there are extremely short
contacts involving the hydrogens of the CH2 group; normal-
ised values are H1A ؒ ؒ ؒ Cl1 2.45 Å for 1 and H1A ؒ ؒ ؒ
O91(acetone) 2.39 Å for 2. In addition, there is a weak
intermolecular interaction C–H ؒ ؒ ؒ Au, (H ؒ ؒ ؒ Au 2.93 Å and
Fig. 1 Molecular structure of the dinuclear monobridged derivative 1.
D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
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Table 3 Hydrogen bonds for complexes 1, 2 and 4 (Å and Њ)
Compound 1
D–H ؒ ؒ ؒ A
d(D–H)
d(H ؒ ؒ ؒ A)
d(D ؒ ؒ ؒ A)
Є(DHA)
C(1)–H(1A) ؒ ؒ ؒ Cl(1)#1
C(1)–H(1B) ؒ ؒ ؒ Cl(2)#1
C(6)–H(6C) ؒ ؒ ؒ Cl(2)#1
C(26)–H(26) ؒ ؒ ؒ Cl(2)#1
C(5)–H(5) ؒ ؒ ؒ Cl(1)#2
C(6)–H(6A) ؒ ؒ ؒ Cl(1)#2
C(99)–H(99B) ؒ ؒ ؒ Cl(1)#3
0.99
0.99
0.98
0.95
1.00
0.98
0.98
2.54
2.84
2.92
2.83
2.92
2.98
2.97
3.518(3)
3.790(2)
3.789(3)
3.771(3)
3.611(3)
3.605(3)
3.835(4)
170.1
161.3
147.9
170.5
127.0
122.3
147.2
Symmetry transformations used to generate equivalent atoms: #1 x, Ϫy ϩ 1/2, z ϩ 1/2; #2 Ϫx ϩ 2, Ϫy ϩ 1, Ϫz ϩ 1. #3 Ϫx ϩ 1, Ϫy ϩ 1, Ϫz ϩ 1.
Compound 2
D–H ؒ ؒ ؒ A
d(D–H)
d(H ؒ ؒ ؒ A)
d(D ؒ ؒ ؒ A)
Є(DHA)
C(1)–H(1A) ؒ ؒ ؒ O(91)
C(2)–H(2) ؒ ؒ ؒ O(91)
0.99
1.00
0.95
0.95
0.99
0.98
0.95
0.95
0.98
2.45
2.55
2.96
3.01
2.93
3.14
3.14
2.96
3.06
3.253(4)
3.401(4)
3.797(3)
3.952(3)
3.870(3)
4.027(3)
4.016(3)
3.799(3)
3.789(5)
137.4
142.4
148.2
170.5
158.4
150.8
153.3
148.3
132.1
C(24)–H(24) ؒ ؒ ؒ Br(1)#1
C(23)–H(23) ؒ ؒ ؒ Br(1)#2
C(1)–H(1B) ؒ ؒ ؒ Br(2)#2
C(6)–H(6C) ؒ ؒ ؒ Br(2)#2
C(16)–H(16) ؒ ؒ ؒ Br(2)#2
C(22)–H(22) ؒ ؒ ؒ Br(2)#2
C(93)–H(93C) ؒ ؒ ؒ Br(2)#2
Symmetry transformations used to generate equivalent atoms: #1 x Ϫ 1/2, y Ϫ 1/2, z; #2 Ϫx ϩ 3/2, y Ϫ 1/2, Ϫz ϩ 1/2.
Compound 4
D–H ؒ ؒ ؒ A
d(D–H)
d(H ؒ ؒ ؒ A)
d(D ؒ ؒ ؒ A)
Є(DHA)
C(37)–H(37B) ؒ ؒ ؒ F(4)#1
C(35)–H(35) ؒ ؒ ؒ F(4)#2
C(32)–H(32) ؒ ؒ ؒ F(4)#1
C(43)–H(43C) ؒ ؒ ؒ Au(2)#3
0.97
0.93
0.93
0.96
2.48
2.48
2.61
2.93
3.436(6)
3.160(7)
3.275(6)
3.852(6)
169.9
130.5
128.7
162.6
Symmetry transformations used to generate equivalent atoms: #1 Ϫx, y ϩ 1/2, Ϫz ϩ 1/2; #2 Ϫx, Ϫy,Ϫz ϩ 1; #3 x, Ϫy ϩ 1/2, z Ϫ 1/2.
C–H ؒ ؒ ؒ Au 163Њ), involving one hydrogen of a CH3 group in
compound 4 (see Table 3).
of gold() complexes are two-coordinate, whilst three- and
four-coordinate species are uncommon.9
Moreover, NMR spectra confirmed the presence of head–
head and head–tail isomers (see Fig. 3) in ca. the following pro-
portion (% head–head isomer : % head–tail isomer): 70 : 30 (7),
60 : 40 (8), 75 : 25 (9), 50 : 50 (10), 65 : 35 (11). Phosphorus
NMR spectra showed AAЈXXЈ spin systems with two sets of
very close resonances, summarised in Table 4. The first half
system (AAЈ and XXЈ parts are equal in AAЈXXЈ spin systems)
consists of four lines (close to a doublet of doublets) with a
2J(PPh2–PiPr2) around 300 Hz because of trans coupling and a
2J(PPh2–PiPr2) around 45 Hz due to coupling in the same
diphosphine, assigned to the head–tail isomer (4J(PPh2–PPh2) =
4J(PiPr2–PiPr2) ≈ 0). The second half system consists of a
pseudo-triplet (with inverted intensity 2 : 1 : 2) or a triplet (less
intense) in the middle of a doublet, due to strong 2J(PPh2–PPh2)
and 2J(PiPr2–PiPr2) (found by calculation in the range 255–295
Synthesis and characterization of doubly-bridged derivatives
The reaction of the unsymmetrical diphosphine with the gold()
complex [AuXL] or [Au(tht)2]A in molar ratio 1 : 1 in dichloro-
methane, leads to the doubly-bridged dinuclear gold() com-
plexes 7–11 (see Scheme 2). These derivatives are air-and
moisture-stable white (7–8, 10–11) or yellow (9) solids at room
temperature. They were characterised by elemental analysis,
conductivity, mass, IR and NMR spectroscopies (see Experi-
mental section). The main features are: (a) the IR spectrum of 7
shows an absorption at 326 cmϪ1 arising from coordination of
chloride; besides, the spectra of derivatives 10 and 11 show
absorptions, respectively, at 1253 and 637 cmϪ1, 1092 (s)
and 623 cmϪ1, corresponding to ionic triflate and perchlorate;
(b) their acetone solutions behave as 1 : 2 electrolytes for
complexes 10–11, and are essentially non-conducting for 7–9
(although some molar conductivity is observed). Therefore
halides are coordinated to the gold() centres but triflate or
perchlorate are not. This is important because the vast majority
2
Hz), and J(PPh2–PiPr2) ca. 50 Hz in the same diphosphine,
from the head–head isomer (see Experimental section).10 Now,
the chemical shifts sequence is the same for both phosphine
arms: I < Br < Cl < ClO4, CF3SO3. The 1H and 1H{31P} NMR
Scheme 2
Fig. 3 Head–head and head–tail isomers.
D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
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Table 4 31P{1H} NMR data for doubly-bridged complexes 7–11.a
Table 5 Selected bond distances (Å) and angles (Њ) within molecules
[Au2I2(µ-PiPr2CH2PPh2)2] 9 and [Au2(µ-PiPr2CH2PPh2)2](CF3SO3)2 10
Complex
δ(PPh2)
δ(PiPr2)
Complex 9
7a
7b
33.2
33.7
31.3
31.7
27.6
28.9
37.6
37.5
36.5
36.7
59
59.1
57.6
57.7
53.1
53.6
61.2
62.2
59.6
60.8
Au(1)–P(1)
Au(1)–P(2)
Au(1)–Au(1)#1
Au(1)–I(1)
2.3086(19) P(1)–Au(1)–I(1)
2.3302(19) P(2)–Au(1)–I(1)
113.05(5)
92.48(5)
95.563(18)
92.95(5)
84.21(5)
8a
8b
2.9931(6)
3.0999(6)
Au(1)#1–Au(1)–I(1)
P(1)–Au(1)–Au(1)#1
P(2)–Au(1)–Au(1)#1
9a
9b
P(1)–Au(1)–P(2) 154.47(7)
10a
10b
11a
11b
Symmetry transformations used to generate equivalent atoms: #1 Ϫx ϩ
1, Ϫy, Ϫz ϩ 2.
a Head–head isomer is denoted a; head–tail isomer is denoted b.
Complex 10
Au(1)–P(1)
Au(1)–P(2)
Au(1)–Au(1)#1
2.2993(14)
2.3020(14)
2.9838(5)
P(1)–Au(1)–P(2)
P(1)–Au(1)–Au(1)#1
P(2)–Au(1)–Au(1)#1
172.32(5)
92.13(4)
89.70(4)
spectra are similar to those found in monobridged derivatives
1–6 but more complicated because of the presence of two iso-
mers (two CH2 resonances can be distinguished for derivatives
9–11).
Symmetry transformations used to generate equivalent atoms: #1 Ϫx ϩ
2, Ϫy ϩ 1, Ϫz ϩ 1.
X-Ray crystal structure determination of 9 and 10
Additionally, gold centres in complex 9 are three-coordinated
in a T-shaped AuP2I geometry with a Au–I bond length of
3.0999(6) Å, longer than a typical Au–I bond length. This
geometry is typical of [Au2X2(µ-diphosphine)2] (X = halide),9
although different configurations have been reported for iodo
derivatives: (a) T-shaped as adopted for derivative 9 in [Au2I2-
(µ-dcpm)2] (Au–I: 2.9960(7) Å);5b (b) T-shaped geometry with
the two gold centres symmetrically or asymmetrically bridged
by one iodo, as reported in [Au2I(µ-dppm)2]I (Au–I: 3.127(2)
and 3.196(2) Å)11 and in [Au2I(µ-dppm)2][Au(CN)2] (Au–I:
3.161(3) and 3.342(3) Å);12 (c) T-shaped as shown in derivative
9, but additionally one iodo bridges two dinuclear units (one
gold is tetra-coordinated) as found in [Au2I2(µ-dmpe)2] (dmpe =
1,2-bis(dimethylphosphino)ethane; Au–I: 3.151(1)–3.425(1)
Å).13 The P–Au–P angle in 9, 154.47(7)Њ, deviates from linear
geometry; this value is in line with those found in related three-
coordinated gold() compounds such as 155.9(1)Њ in [Au2Cl2-
(µ-dppm)2],14 156.5(1)Њ in [Au2Br2(µ-dppm)2],11 or 157.93(7)Њ in
[Au2I2(µ-dcpm)2].5b The closest Au ؒ ؒ ؒ anion contact in 10,
Au ؒ ؒ ؒ OSO3CF3 3.284(4) Å, is significantly longer than that of
9 as reported in the related series [Au2X2(µ-dcpm)2] and [Au2-
(µ-dcpm)2]A2.5a,b Complex 10 displays two short C–H ؒ ؒ ؒ O
(anion) contacts of 2.39 Å (150.9Њ) and 2.48 Å (130.7Њ), that
could be considered as hydrogen bonds.
The molecular structures of complexes 9 and 10 are shown
in Figs. 4 and 5, respectively. Selected bonds and angles are
summarised in Table 5. The molecules are eight-membered
diauracycles in a chair conformation; both display crystallo-
graphic inversion symmetry. Therefore we have found the
head–tail isomer for both complexes, although in solution a
mixture was always found; the redissolution of the crystals
again led to a mixture of isomers in solution. This fact can be
explained because of phosphine exchange in solution (fluxion-
ality in phosphino gold() derivatives is not uncommon),
although a mixture of isomers in the crystals can not be
excluded. They display short gold–gold intramolecular inter-
actions of 2.9931(6) and 2.9838(5) Å respectively for 9 and
10, which are shorter than those found in the monobridged
complexes; there are no intermolecular gold–gold interactions.
Photoluminescence studies
The solid-state emission and excitation spectra for complexes
1–11 have been determined at 298 and 77 K and the results
are summarised in Table 6. In Fig. 6 are plotted the solid state
Fig. 4 Molecular structure of the dinuclear doubly-bridged derivative
9; H-atoms are omitted for clarity.
excitation and emission spectra of complex 4 (at 298 K). Only
the organometallic monobridged digold() complex 4 [(AuC6F5)2-
(µ-PiPr2CH2PPh2)] emits intensely at room temperature with
emission maxima of 445 nm, whilst the other monobridged
derivatives do not. At 77 K derivatives 1–4 are photoluminescent
with the maxima in the range 440–486 nm, depending on the
auxiliary ligand bonded to the diphosphine–gold fragment and
following the series: C6F5 < Cl, Br < I, therefore totally different
than predicted by the strength of the gold()–gold() inter-
action (emission maxima should be: C6F5 > Br > Cl). Addi-
tionally for complex 4 can be obtained two different emission
spectra depending on the excitation frequency. The mononuclear
gold() derivative 6 does not emit, which confirms the role of the
gold() centres and of the gold()–gold() interactions. The dithio-
carbamato–gold() complex 5 does not emit, which may be
explained because secondary sulfur–gold bonds should red-shift
the emission but this could disappear.15,16
Dinuclear doubly bridged complexes 7–11 are intensely
luminescent at room and low temperature, as for the related
Fig. 5 Structure of the dinuclear doubly-bridged cation of 10; H-
atoms are omitted for clarity.
D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
4532

View Article Online
(external, 1H), CFCl3 (external, 19F) and 85% H3PO4 (external,
Table 6 Emission and excitation maxima (in nm) measured for
complexes 1–11 in the solid state
31P). 31P{1H} NMR spectra of derivatives 7–11 were calculated
by using the software package Swan-NMR 3.3.5. C, H, N and S
analyses were performed with a Perkin-Elmer 2400 micro-
analyzer. Conductivities were measured in acetone solution
with a Philips PW 9509 apparatus. Mass spectra were recorded
on a VG Autospec using FAB technique (with Cs gun) and
3-nitrobenzyl alcohol as matrix. Emission and excitation
spectra were measured in the solid state as finely pulverised KBr
mixtures at room temperature and 77 K with a Perkin-Elmer
LS-50B spectrofluorometer.
298 K
77 K
Complex
λexc
λem
λexc
λem
1
2
3
4
–
–
–
335
–
–
–
445
320
325
342
327
350
–
456
457
471, 481
440
440, 486
–
–
470, 520 (sh)
508
469
5
6
7
–
–
–
–
500
–
Preparation of [(AuX)2(ꢀ-PiPr2CH2PPh2)] (X ؍ Cl 1, Br 2, I 3,
C6F5 4)
280–380
325
380
322
8
320
380
393
334
340
480
491, 527 (sh)
513
482
478
To a 10 mL dichloromethane solution of [AuX(tht)]18,19 (tht =
tetrahydrothiophene; 0.2 mmol; X = Cl, 64 mg; C6F5 90 mg) or
[AuX(AsPh3)]20 (0.2 mmol; X = Br, 117 mg; I 126 mg) was
added diisopropylphosphine(diphenylphosphine)methane21 (33
mg, 0.1 mmol). After stirring for 1 h, the solution was concen-
trated to ca. 3 mL. Addition of hexane (1, 2, 4) or diethyl ether
(3) afforded complexes 1–4 as white solids, which were washed
with more diethyl ether or hexane (2 × 5 mL). Yield of 1: 75%.
9
10
11
346,387
325
335
499
459
463
1
3
Λ: 3 ohmϪ1 cm2 molϪ1. H NMR: δ 1.18 (dd, 6H, JHH = 7.1,
3JHP = 19 Hz, CH3), 1.26 (dd, 6H, JHH = 6.9, JHP = 17.2 Hz,
3
3
CH3), 2.37 (m, 2H, CH), 3.54 (dd, 2H, 2JHP = 10.5 and 11.9 Hz,
CH2), 7.6–8.1 (m, 10H, Ph); 31P{1H} NMR: δ 39.2 (d, JPP
=
2
51.9 Hz, PPh2), 54.4 (d, PPr2). IR: 326 (m, ν(Au–Cl)) cmϪ1
.
i
Found: C, 28.8; H, 3.15. C19H26Au2Cl2P2 requires: C, 29.2; H,
3.35%. LSIMS (m/z, %, assignment): 745 (76, [M Ϫ Cl]ϩ). Yield
of 2: 83%. Λ: 8 ohmϪ1 cm2 molϪ1. 1H NMR: δ 1.18 (dd, 6H, JHH
= 7.1, JHP = 18.9 Hz, CH3), 1.25 (dd, 6H, 3JHH = 6.9, 3JHP = 17.4
Hz, CH3), 2.52 (m, 2H, CH), 3.53 (dd, 2H, 2JHP = 10.5 and 11.8
Hz, CH2), 7.5–8.1 (m, 10H, Ph); 1H{31P} NMR: δ 1.19 (d, 6H,
3JHH = 7.1 Hz, CH3), 1.25 (d, 6H, 3JHH = 6.9, CH3), 2.52 (m, 2H,
CH), 3.53 (s, 2H, CH2). 31P{1H} NMR: δ 35.4 (d, 2JPP = 55.9 Hz,
PPh2), 51.4 (d, iPPr2). Found: C, 26.5; H, 2.95. C19H26Au2Br2P2
requires: C, 26.25; H, 3.0%. LSIMS (m/z, %, assignment): 791
(100, [M Ϫ Br]ϩ). Yield of 3: 70%. Λ: 10 ohmϪ1 cm2 molϪ1. 1H
Fig. 6 Excitation and emission spectra in the solid state at 298 K of
complex 4; intensity in arbitrary units.
series [Au2(µ-P–P)2]2ϩ (P–P = dppm, dcpm) with different
anions. A second spectrum (less intense) is obtained by chang-
ing the excitation frequency for complexes 7 (at 77 K) and 8 (at
298 K). At room temperature the emission maxima range from
480 to 513 nm, in the sequence Br, ClO4, CF3SO3 < Br (second
spectrum) < Cl < I, whilst at low temperature the emission
maxima are in the range 459–508 nm, in the sequence ClO4,
CF3SO3 < Br, Cl < I < Cl (second spectrum). In both cases the
tendency is not the predicted by the strength of the gold–gold
interaction. A blue-shift (from 11 to 30 nm) of the emission
maxima is observed after lowering the temperature. When non-
coordinating counter-ions are present, the results are the same
but with coordinating halide anions, the emission depends on
the nature of the anion, as was previously reported for related
dinuclear derivatives.3,5a,17 In these complexes we have not found
the intense UV emission found in the similar doubly bridged
dcpm digold derivatives (suggested to be the intrinsic gold–
gold centred emission) and they emit only in the visible region,
as reported for doubly bridged dppm digold derivatives. A
deactivating state involving the phenyl rings has been invoked
to explain this fact and could be also proposed for our unsym-
metric diphosphine.5b
3
3
NMR: δ 1.17 (dd, 6H, JHH = 7.3, JHP = 15.8 Hz, CH3), 1.23
3
3
(dd, 6H, JHH = 7.3, JHP = 12.6 Hz, CH3), 2.37 (m, 2H, CH),
2.81 (‘t’, 2H, 2JHP = 9.6 Hz, CH2), 7.5–7.9 (m, 10H, Ph); 31P{1H}
2
i
NMR: δ 32.6 (d, JPP = 62.9 Hz, PPh2), 51.6 (d, PPr2). Found:
C, 23.8; H, 2.8. C19H26Au2I2P2 requires: C, 23.65; H, 2.7%.
LSIMS (m/z, %, assignment): 837 (100, [M Ϫ I]ϩ). Yield of 4:
1
75%. Λ: 7 ohmϪ1 cm2 molϪ1. IR: 955, 792 (s, C6F5) cmϪ1. H
3
3
NMR: δ 1.16 (dd, 6H, JHH = 7.1, JHP = 11.0 Hz, CH3), 1.22
(dd, 6H, 3JHH = 7.1, 3JHP = 11.1 Hz, CH3), 2.3 (m, 2H, CH), 2.84
2
(‘t’, 2H, JHP = 10.3 Hz, CH2), 7.3–8.0 (m, 10H, Ph); 31P{1H}
2
i
NMR: δ 39.5 (dm, JPP = 66.5 Hz, PPh2), 54.8 (dm, PPr2); 19F
3
NMR: δ Ϫ117.5 (m, 2Fo), Ϫ117.7 (m, 2Fo), Ϫ160.2 (t, JFF
=
20.0 Hz, 1Fp), Ϫ160.5 (t, 3JFF = 20.1 Hz, 1Fp), Ϫ164.2 (m, 4Fm).
Found: C, 43.5; H, 2.65. C37H26AuF15P2 requires: C, 43.8; H,
2.6%. LSIMS (m/z, %, assignment): 877 (100, [M Ϫ C6F5]ϩ),
1044 (15, [M]ϩ).
Preparation of [{Au(S2CN(CH2Ph)2)}2(ꢀ-PiPr2CH2PPh2)] 5
To a dichloromethane solution (10 mL) of 1 (78 mg, 0.1 mmol)
was added NaS2CN(CH2Ph)2 (0.2 mmol, 59 mg). The mixture
was stirred for about 2 h, then filtered through Celite. Concen-
tration to ca. 2 mL and addition of cold 1 : 1 diethyl ether–
hexane (20 mL) afforded complex 5 as a yellow solid. Yield:
Experimental
General
All the reactions were carried out under an argon atmosphere at
room temperature. IR spectra were recorded on a Perkin Elmer
Spectrum One and a Brücker Equinox 55 spectrophotometers,
over the range 4000–200 cmϪ1, by using Nujol mulls between
polyethylene sheets or KBr pellets. 1H, 1H{31P}, 19F and
31P{1H} NMR spectra were recorded on a Bruker ARXؒ300 or
GEMINI 2000 apparatus in CDCl3 solutions (if no other sol-
vent is stated); chemical shifts are quoted relative to SiMe4
67%. Λ: 15 ohmϪ1 cm2 molϪ1. 1H NMR: δ 1.18 (dd, 6H, 3JHH
=
=
3
3
3
6.9, JHP = 17.4 Hz, CH3), 1.26 (dd, 6H, JHH = 7.1, JHP
2
17.4 Hz, CH3), 2.3 (m, 2H, CH), 2.85 (‘t’, 2H, JHP = 10.7 Hz,
CH2), 5.12 (s, 8H, CH2N), 7.3–8.1 (m, 30H, Ph); 31P{1H} NMR:
δ 31.2 (d, 2JPP = 64.3 Hz, PPh2), 54.4 (d, iPPr2). Found: C, 47.25;
H, 4.35; N, 2.05; S, 10.1. C49H54Au2N2P2S4 requires: C, 46.9; H,
4.35; N, 2.25; S, 10.2%. LSIMS (m/z, %, assignment): 982 (100,
[M Ϫ S2CN(CH2Ph)2]ϩ).
D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
4533

D
Table 7 Details of crystal data and structure refinement for complexes 1, 2, 4, 9 and 10
Compound
1ؒCO(CH3)2
2ؒ1.5CO(CH3)2
4
9
10ؒ2CH2Cl2
Empirical formula
Mr
C22H32Au2Cl2OP2
839.25
C23.5H35Au2Br2O1.5P2
957.21
C31H26Au2F10P2
1044.39
C38H52Au2I2P4
1280.41
C44H60Au2Cl4F6O6P4S2
1522.65
T/K
λ/Å
133(2)
0.71073
133(2)
0.71073
100(2)
0.71073
100(2)
0.71073
100(2)
0.71073
Crystal system
Space group
Monoclinic
P21/c
Monoclinic
C2/c
Monoclinic
P21/c
Monoclinic
P21/n
Triclinic
P1
¯
Unit cell dimensions
a/Å
b/Å
14.9066(11)
12.1750(8)
19.7999(14)
16.6728(12)
12.9723(10)
16.9452(13)
12.1033(10)
14.3905(12)
10.0765(9)
11.688(1)
c/Å
α/Њ
14.8415(11)
90
18.2896(12)
90
15.1980(11)
90
12.1366(9)
90
13.2223(12)
70.562(1)
β/Њ
97.518(3)
90
2670.4(3)
105.643(3)
90
5814.1(7)
108.926(2)
90
3160.2(4)
100.234(1)
90
2080.2(3)
69.619(2)
89.378(2)
1366.8(2)
γ/Њ
V/Å3
Z
4
8
4
2
1
Dc/Mg mϪ3
2.087
11.306
2.187
12.956
2.195
9.456
2.044
8.708
1.850
5.814
µ/mmϪ1
F(000)
1576
3568
1960
1208
744
Crystal size/mm
Diffractometer
θ Range data collection/Њ
Index ranges, hkl
Reflections collected
Independent reflections (Rint
Compl. to θ = 30.00Њ (%)
Absorption correction
Max., min. transmission
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [I >2σ(I )]
R indices (all data)
0.17 × 0.13 × 0.07
Bruker SMART 1000 CCD
1.38–30.03.
Ϫ20 to 20, Ϫ17 to 17, Ϫ20 to 20
47562
7785 (0.0344)
99.8
SADABS
0.564, 0.387
7785/49/268
0.989
R1 = 0.0174, wR2 = 0.0374
R1 = 0.0239, wR2 = 0.0386
0.897, Ϫ0.616
0.20 × 0.16 × 0.07
Bruker SMART 1000 CCD
1.62–30.03.
Ϫ27 to 27, Ϫ23 to 23, Ϫ25 to 25
52984
8508 (0.0405)
100.0
SADABS
0.494, 0.283
8508/67/284
0.999
R1 = 0.0199, wR2 = 0.0479
R1 = 0.0255, wR2 = 0.0491
1.427, Ϫ1.195
0.28 × 0.20 × 0.18
Bruker SMART APEX CCD
1.86–28.43.
Ϫ9 to 17, Ϫ22 to 22, Ϫ19 to 16
20427
7342 (0.0418)
92.1
SADABS
1.0000, 0.6997
7342/0/410
0.880
R1 = 0.0350, wR2 = 0.0534
R1 = 0.0494, wR2 = 0.0566
1.649, Ϫ1.178
0.38 × 0.26 × 0.20
Bruker SMART APEX CCD
2.19–28.42.
Ϫ13 to 15, Ϫ16 to 18, Ϫ16 to 9
13318
4802 (0.1046)
91.7
SADABS
0.928, 0.408
4802/0/212
1.045
R1 = 0.0583, wR2 = 0.1470
R1 = 0.0639, wR2 = 0.1501
3.270, Ϫ2.761
0.18 × 0.10 × 0.10
Bruker SMART APEX CCD
1.75–28.49.
Ϫ10 to 13, Ϫ15 to 13, Ϫ16 to 15
9037
6053 (0.0256)
87.2
SADABS
1.000, 0.830
6053/0/311
0.896
)
R1 = 0.0352, wR2 = 0.0692
R1 = 0.0434, wR2 = 0.0710
2.311, Ϫ1.374
Largest diff. peak, hole/e ÅϪ3

View Article Online
Preparation of [Au(C6F5)3(PiPr2CH2PPh2)] 6
(diphenylphosphine)methane (66 mg, 0.2 mmol). After stirring
for 1 h, the solution was concentrated to ca. 3 mL. Addition of
cold diethyl ether–hexane (1 : 1) afforded derivatives 10–11 as
white solids; a second fraction was obtained by concentration
and cooling to Ϫ18 ЊC. Yield of 10: 74%. Λ: 212 ohmϪ1 cm2
To a dichloromethane solution (10 mL) of [Au(C6F5)3(tht)]22
(79 mg, 0.1 mmol) was added diisopropylphosphine(diphenyl-
phosphine)methane (33 mg, 0.1 mmol). After stirring for 1 h,
the solution was concentrated to ca. 3 mL. Addition of cold
hexane (10 mL) afforded 6 as a white solid. A second fraction
was obtained by concentration and cooling to Ϫ18 ЊC. Yield:
1
molϪ1. H NMR: δ 1.11 (m, 12H, CH3), 1.34 (m, 12H, CH3),
2.33 (m, 4H, CH), 3.80 (br, 4H, CH2), 7.4–8.1 (m, 20H, Ph); 1H
NMR (in d6-acetone): δ 1.35 (m, 24H, CH3), 2.53 (m, 4H, CH),
4.18 (m, 4H, CH2), 7.5–8.1 (m, 20H, Ph); 1H{31P} NMR: δ 1.11
70%. Λ: 5 ohmϪ1 cm2 molϪ1. IR: 966, 792 (s, C6F5) cmϪ1. H
1
NMR: δ 1.10 (dd, 6H, 3JHH = 7, 3JHP = 18.1 Hz, CH3), 1.16 (dd,
6H, 3JHH = 7, 3JHP = 17.1 Hz, CH3), 2.40 (d, 2H, 2JHP = 10.8 Hz,
3
(d, 12H, JHH = 7 Hz, CH3), 1.34 (d, 12H, CH3), 2.33 (m, 4H,
1
CH), 3.8 (br, 4H, CH2); H{31P} NMR (in d6-acetone): head–
CH2), 2.61 (m, 2H, CH), 7.3–7.6 (m, 10H, Ph); H{31P} NMR
1
3
head isomer: δ 1.29 (d, 12H, JHH = 7 Hz, CH3), 1.37 (d, 12H,
δ 1.10 (d, 6H, 3JHH = 7 Hz, CH3), 1.16 (d, 6H, CH3), 2.40 (s, 2H,
CH3), 2.52 (sept, 4H, CH), 4.19 (s, 4H, CH2); head–tail isomer:
CH2), 2.61 (sept, 2H, CH); 31P{1H} NMR: δ Ϫ27.5 (d, JPP
=
2
3
δ 1.33 (d, 12H, JHH = 7 Hz, CH3), 1.40 (d, 12H, CH3), 2.62
i
24.3 Hz, PPh2), 38.4 (m, PPr2); 19F NMR: δ Ϫ120.2 (m, 4Fo),
Ϫ123.1 (m, 2Fo), Ϫ156.9 (t, 3JFF = 20.0 Hz, 2Fp), Ϫ158.4 (t, 3JFF
= 20.1 Hz, 1Fp), Ϫ161 (m, 4Fm), Ϫ162.1 (m, 2Fm). Found: C,
35.7; H, 2.65. C31H26Au2F10P2 requires: C, 35.65; H, 2.5%.
LSIMS (m/z, %, assignment): 847 (100, [M Ϫ C6F5]ϩ), 1015 (12,
[M ϩ H]ϩ).
(sept, 4H, CH), 4.18 (s, 4H, CH2); 31P{1H} NMR: head–head
i
isomer: δ 37.6 (‘t’, N = 23.1 Hz, PPh2), 61.2 (‘t’, PPr2), with
calculated 2J(PiPr2–PiPr2), 2J(PPh2–PPh2) = 295, 260 Hz,
2
2J(PPh2–PiPr2) = 45 Hz; head–tail isomer: δ 37.6 (dd, JPP
=
303.9 and 40 Hz, PPh2), 62.2 (dd, iPPr2). IR: 1253 (s) and 637 (s,
CF3SO3) cmϪ1. Found: C, 36.4; H, 4.0; S, 4.65. C39H52Au2-
F3O3P4S requires: C, 36.25; H, 3.95; S, 4.85%. Yield of 11: 70%.
Λ: 145 ohmϪ1 cm2 molϪ1. 1H NMR: δ 1.09 (m, 12H, CH3), 1.37
(m, 12H, CH3), 2.29 (m, 4H, CH), 3.64 (br, 4H, CH2), 7.5–8.0
Preparation of [Au2X2(ꢀ-PiPr2CH2PPh2)2] (X ؍ Cl 7, Br 8, I 9)
To a 10 mL dichloromethane solution of [AuCl(tht)] (64 mg,
0.2 mmol) or [AuX(AsPh3)] (0.2 mmol; X = Br, 117 mg; I 126
mg) was added diisopropylphosphine(diphenylphosphine)-
methane (66 mg, 0.2 mmol). After stirring for 1 h, the solution
was concentrated to ca. 3 mL. Addition of cold hexane (7) or
diethyl ether (8–9) afforded the corresponding complexes as
white (7–8) or yellow solids (9). A second fraction was obtained
by concentration and cooling to Ϫ18 ЊC. Yield of 7: 65%. Λ: 51
(m, 20H, Ph); H{31P} NMR: head–head isomer: δ 1.09 (d,
1
3
12H, JHH = 7 Hz, CH3), 1.36 (d, 12H, CH3), 2.33 (sept, 4H,
CH), 3.64 (s, 4H, CH2); head–tail isomer: δ 1.09 (d, 12H, 3JHH
=
7 Hz, CH3), 1.36 (d, 12H, CH3), 2.27 (sept, 4H, CH), 3.63 (s,
4H, CH2); 31P{1H} NMR: head–head isomer: δ 36.5 (‘t’, N =
23.2 Hz, PPh2), 59.6 (‘t’, iPPr2), with calculated 2J(PiPr2–PiPr2),
2J(PPh2–PPh2) = 294, 261 Hz, 2J(PPh2–PiPr2) = 48 Hz; head–tail
2
1
ohmϪ1 cm2 molϪ1. H NMR: δ 1.13 (m, 12H, CH3), 1.27 (m,
isomer: δ 36.7 (dd, JPP = 306.2 and 45.9 Hz, PPh2), 60.8 (dd,
iPPr2); 19F NMR: δ Ϫ78.9 (s, CF3). IR: 1092 (s) and 623 (s,
ClO4) cmϪ1. Found: C, 36.9; H, 4.5. C38H52Au2Cl2O8P4 requires:
C, 37.25; H, 4.25%.
12H, CH3), 2.36 (br, 4H, CH), 3.9 (br, 4H, CH2), 7.3–8.1 (m,
20H, Ph); 1H{31P} NMR: δ 1.13 (d, 12H, 3JHH = 6.9 Hz, CH3),
1.27 (d, 12H, CH3), 2.36 (m, 4H, CH), 3.9 (s, 4H, CH2); 31P{1H}
NMR: head–head isomer: δ 33.2 (m, PPh2), 59 (m, iPPr2); head–
tail isomer: δ 33.7 (dm, 2JPP = 245.3 Hz, PPh2), 59.1 (dm, iPPr2);
31P{1H} NMR (Ϫ50 ЊC): head–head isomer: δ 33.6 (‘t’, N = 23.7
Crystal structure determination of 1, 2, 4, 9 and 10
Some crystallographic data of [(AuX)2(µ-PiPr2CH2PPh2)] (X =
Cl, Br, C6F5), [Au2I2(µ-PiPr2CH2PPh2)2] and [Au2(µ-PiPr2CH2-
PPh2)2](CF3SO3)2 are given in Table 7. The structures were
refined anisotropically (full-matrix least-squares) on F 2 (pro-
gram SHELXL-97)24 using a system of restraints (to light-atom
U values and local ring symmetry) for complexes 1 and 2. All
non-hydrogen atoms were refined anisotropically. Hydrogen
atoms were included using a riding model. Special details of
refinement for2: The second acetone molecule is disordered over
a twofold axis; it was refined isotropically without hydrogens.
CCDC reference numbers 216496–216500.
i
Hz, PPh2), 58.6 (‘t’, PPr2), with calculated 2J(PiPr2–PiPr2),
2J(PPh2–PPh2) = 260, 255 Hz, 2J(PPh2–PiPr2) = 47.5 Hz; head–
tail isomer: δ 33.9 (dd, 2JPP = 297.4 and 44 Hz, PPh2), 58.6 (dd,
iPPr2). IR: 326 (m, ν(Au–Cl)) cmϪ1. Found: C, 41.2; H, 4.55.
C38H52Au2Cl2P4 requires: C, 41.6; H, 4.75. LSIMS (m/z, %,
assignment): 745 (100, [M Ϫ Cl Ϫ PiPr2CH2PPh2]ϩ), 1025 (77,
[M Ϫ Cl2 Ϫ H]ϩ). Yield of 8: 77%. Λ: 71 ohmϪ1 cm2 molϪ1. H
1
NMR: δ 1.11 (m, 12H, CH3), 1.33 (m, 12H, CH3), 2.46 (m, 4H,
CH), 3.84 (br, 4H, CH2), 7.3–8.1 (m, 20H, Ph); H{31P} NMR:
1
3
δ 1.11 (d, 12H, JHH = 7 Hz, CH3), 1.33 (d, 12H, CH3), 2.46 (m,
4H, CH), 3.84 (br, 4H, CH2); 31P{1H} NMR: head–head isomer:
See http://www.rsc.org/suppdata/dt/b3/b309116c/ for crystal-
lographic data in CIF or other electronic format.
i
δ 31.3 (‘t’, N = 27 Hz, PPh2), 57.6 (‘t’, PPr2), with calculated
2
2
2J(PiPr2–PiPr2), J(PPh2–PPh2) = 278, 270 Hz, J(PPh2–PiPr2) =
52 Hz; head–tail isomer: δ 31.7 (dd, 2JPP = 292.2 and 47 Hz, PPh2),
57.7 (dd, iPPr2). Found: C, 38.75; H, 4.45. C38H52Au2Br2P4
requires: C, 38.45; H, 4.4%. LSIMS (m/z, %, assignment): 789
(100, [M Ϫ Br Ϫ PiPr2CH2PPh2]ϩ). Yield of 9: 68%. Λ: 18 ohmϪ1
cm2 molϪ1. 1H NMR: δ 1.13 (m, 12H, CH3), 1.31 (m, 12H, CH3),
2.51 (m, 4H, CH), 3.81 (br, 4H, CH2), 7.5–8.0 (m, 20H, Ph);
1H{31P} NMR: δ 1.13 (m, 12H, CH3), 1.31 (m, 12H, CH3), 2.51
(m, 4H, CH), 3.81 and 3.91 (s, 4H, CH2); 31P{1H} NMR: head–
Acknowledgements
We thank the Dirección General de Investigación Científica y
Técnica (project BQU2001–2409-C02–01) and the Fonds der
Chemischen Industrie for financial support. We also thank
Dr J. Galbán (Universidad de Zaragoza, Spain) for kindly
providing apparatus facilities.
i
head isomer: δ 27.7 (‘t’, N = 29 Hz, PPh2), 53.1 (‘t’, PPr2), with
2
2
2
calculated J(PiPr2–PiPr2) = J(PPh2–PPh2) = 264 Hz, J(PPh2–
References
PiPr2) = 56.5 Hz; head–tail isomer: δ 28.9 (dd, 2JPP = 282 and 54.1
Hz, PPh2), 53.6 (dd, PPr2). Found: C, 35.85; H, 3.85. C38H52-
i
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Au2I2P4 requires: C, 35.65; H, 4.1%. LSIMS (m/z, %, assignment):
837 (67, [M Ϫ I Ϫ PiPr2CH2PPh2]ϩ).
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Preparation of [Au2(ꢀ-PiPr2CH2PPh2)2]A2 A ؍ CF3SO3 10,
ClO4 11
To a dichloromethane solution (10 mL) of [Au(tht)2]A23
(0.2 mmol) prepared in situ was added diisopropylphosphine-
D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
4535

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D a l t o n T r a n s . , 2 0 0 3 , 4 5 2 9 – 4 5 3 6
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