Hydrogen-bonded networks: (phosphine) gold (I) 4-amino-2-pyrimidine-thiolates

Article abstract of DOI:10.1016/S0022-328X(01)01284-0

Treatment of the gold(I) halide complexes LAuCl (where L = PMe₃, PEt₃, PPh₃, PPh₂Py) and PP(AuCl)₂ [where PP = bis(-diphenylphosphino)methane; 1,1′-bis(diphenylphosphino)ferrocene] with 4-amino-2-pyrimidine-thiol (2-SPym-4-NH₂) (one or two equivalents as required) in the presence of sodium methoxide provides the corresponding (phosphine)gold(I) thiolate complexes LAu(2-SPym-4-NH₂) and PP[Au(2-SPym-4-NH₂)]₂, respectively. A polyaurated product [(Ph₃PAu)₂(2-SPym-4-NH₂)]BF₄ is obtained on treating the thiol with the oxonium complex [(Ph₃PAu)₃O]BF₄. The compounds LAu(2-SPym-4-NH₂) (L = PPh₃, PPh₂Py, PEt₃) and [(dppm)Au₂(2-SPym-4-NH₂)₂] have been investigated crystallographically.

Full text of DOI:10.1016/S0022-328X(01)01284-0

Journal of Organometallic Chemistry 643–644 (2002) 313–323
www.elsevier.com/locate/jorganchem
Hydrogen-bonded networks: (phosphine)gold(I)
4-amino-2-pyrimidine-thiolates
James D.E.T. Wilton-Ely, Annette Schier, Norbert W. Mitzel, Stefan Nogai,
Hubert Schmidbaur *
Anorganisch-chemisches Institut, Technische Uni6ersita¨t Mu¨nchen, Lichtenbergstrasse 4, D-85747 Garching, Germany
Received 13 July 2001; accepted 20 September 2001
Abstract
Treatment of the gold(I) halide complexes LAuCl (where L=PMe3, PEt3, PPh3, PPh2Py) and PP(AuCl)2 [where PP=bis(-
diphenylphosphino)methane; 1,1%-bis(diphenylphosphino)ferrocene] with 4-amino-2-pyrimidine-thiol (2-SPym-4-NH2) (one or two
equivalents as required) in the presence of sodium methoxide provides the corresponding (phosphine)gold(I) thiolate complexes
LAu(2-SPym-4-NH2) and PP[Au(2-SPym-4-NH2)]2, respectively. A polyaurated product [(Ph3PAu)2(2-SPym-4-NH2)]BF4 is ob-
tained on treating the thiol with the oxonium complex [(Ph3PAu)3O]BF4. The compounds LAu(2-SPym-4-NH2) (L=PPh3,
PPh2Py, PEt3) and [(dppm)Au2(2-SPym-4-NH2)2] have been investigated crystallographically. © 2002 Elsevier Science B.V. All
rights reserved.
Keywords: Gold(I) complexes; 4-Amino-2-pyrimidine-thiol; Hydrogen bonding; Aurophilicity; Tertiary phosphine complexes; Thiolate complexes
aurophilic contacts (being interactions of comparable
energies in the range 6–12 kcal mol−1) has been dis-
cussed in a number of recent publications [7–11], in
particular, it offers the possibility of using these ‘weak’
interactions to construct supramolecular networks in a
controlled manner.
4-Amino-2-pyrimidine-thiol was chosen as the subject
of this study as a ligand with four sites available for
metal coordination and/or hydrogen bonding interac-
tions. As expected, the first site of attack for gold was
at the thiol sulfur atom to give thiolate complexes of
the general formula [R3PAu(2-SPym-4-NH2)] (PR3=
PMe3, PEt3, PPh3, PPh2Py) in reactions carried out
with R3PAuCl and base. The structures of single crys-
tals of three complexes (PR3=PEt3, PPh3, PPh2Py)
were determined in order to investigate the solid state
interactions between the molecules. As a useful com-
1. Introduction
Thiolate complexes have to be accorded a special
place among the compounds of gold [1]. They have
found use in a wide range of applications ranging from
anti-arthritis [2] drugs to ‘liquid gold’ pastes in the
ceramics and glass industry [3]. Furthermore, much of
gold thin film technology and chemistry of self-assem-
bly monolayers depend on the special properties of
gold(I)–sulfur systems [4]. Academic interest in the
coordination properties of thiols to gold(I) species is
well established and has been heightened by the recent
observation that many of these complexes display novel
luminescence properties [5].
Our recent interest in polydentate, nitrogen-contain-
ing thiol ligands has led to the observation that this
class of compounds is capable of displaying a rich and
unusual chemistry [6]. The primary bonding sites are
the thiol groups, however the nitrogen donors can also
be expected to play an important role, especially in the
solid state. The combination of hydrogen-bonding and
parison,
the
isocyanide
analogue
[2,6-
(CH3)2C6H3NCAu(2-SPym-4-NH2)] was also prepared
by the reaction between 2-SPym-4-NH2 and
[ClAuCNC6H3(CH3)2-2,6] in the presence of sodium
methoxide. Unfortunately, this complex did not yield
crystals suitable for a structural investigation.
* Corresponding author. Tel.: +49-89-3209-3130; fax: +49-89-
3209-3125.
E-mail address: h.schmidbaur@lrz.tum.de (H. Schmidbaur).
Two digold species were prepared through the use of
the bis(phosphine)gold complexes (dppm)(AuCl)2 and
0022-328X/02/$ - see front matter © 2002 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)01284-0

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(dppf)(AuCl)2 which reacted readily with two molar
equivalents of 4-amino-2-pyrimidine-thiol and 2.2
moles of NaOMe to provide the compounds
(dppm)[Au(2-SPym-4-NH2)]2 and (dppf)[Au(2-SPym-4-
NH2)]2, respectively. The former of these yielded suit-
able crystals for a diffraction study on crystallization
from dimethylformamide. A further dinuclear species
[(Ph3PAu)2(2-SPym-4-NH2)]BF4 was obtained through
the action of the oxonium species [(Ph3PAu)3O]BF4 on
4-amino-2-pyrimidine-thiol.
[(Ph3PAu)3O]BF4 [18] were prepared following litera-
ture procedures. The preparation of the mononuclear
complexes 1–5 and the bimetallic compounds 6–8 are
shown in Schemes 1 and 2, respectively.
2.2. [Me3PAu(2-SPym-4-NH2)] (1)
An MeOH suspension (5 ml) of 4-amino-2-pyrim-
idine-thiol (20 mg, 0.16 mmol) and sodium methoxide
(10 mg, 0.19 mmol) was added dropwise to a stirred
solution of [Me3PAuCl] (50 mg, 0.16 mmol) in CH2Cl2
(15 ml). After stirring for 2 h, all solvent was removed
and the crude product dissolved in CH2Cl2 (30 ml) and
filtered through diatomaceous earth to remove NaCl.
After concentration of the solution to ca. 10 ml, pen-
tane (20 ml) was carefully added to precipitate a color-
less solid. This was washed with pentane (20 ml) and
dried. Yield: 51% (33 mg). MS (FAB) m/z=400, 23%
[M]+, 307, 25% [M−PMe3−NH2]+, 273, 16% [M−
SR]+. 31P{1H}-NMR (CD2Cl2, ppm): l −1.5. 1H-
NMR (CD2Cl2, ppm): l 1.59 (d, 9H, CH3, JHP=10.3
Hz), 4.66 (s, 2 H, NH2), 6.03 (d, 1H, H5, JHH=5.7 Hz)
7.83 (d, 1H, H6, JHH=5.7 Hz). Anal. Calc. for
C7H13AuN3S: C, 21.06; H, 3.28; N, 10.53. Found: C,
21.52; H, 3.44; N, 10.86%.
2. Experimental
2.1. General information
The experiments were carried out routinely in air.
NMR: JEOL GX 400 spectrometer using deuterated
solvents with the usual standards at 25 °C. MS: Varian
MAT311A instrument (FAB, p-nitrobenzyl alcohol).
IR: Perkin–Elmer 1600 FTIR. The ligand 4-amino-2-
pyrimidine-thiol (4-HSPym-2-NH2) was obtained com-
mercially. The complexes [R3PAuCl] (R=Me [12], Et
[13], Ph [12]; R3P=Ph2PPy [14]), [(dppm)(AuCl)2] [15],
[(dppf)(AuCl)2] [16], [(2,6-Me2C6H3NC)AuCl] [17] and
Scheme 1. Preparation of the mononuclear complexes 1–5.
Scheme 2. Preparation of the bimetallic compounds 6–8. (i) dppm(AuCl)2, 2NaOMe; (ii) dppf(AuCl)2, 2NaOMe; (iii) [(Ph3PAu)3O]BF4, NaBF4.

J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
315
Table 1
Crystal data and structure refinement parameters for compounds 2–4 and 6
2
3·0.5CH2Cl2
4·CH2Cl2
6·DMF
Empirical formula
Formula weight
Temperature (°C)
Crystal system
Space group
Unit cell dimensions
C10H19AuN3PS
441.28
−130
Orthorhombic
Pna21
C22.5H20AuClN3PS
627.86
−130
C22H20AuCl2N4PS
671.32
−130
C36H37Au2N7OP2S2
1103.72
−130
Monoclinic
P21
Triclinic
Triclinic
(
(
P1
P1
,
a (A)
15.8231(2)
14.7751(2)
25.0687(4)
90
90
90
5860.8(1)
16
8.7123(1)
18.3437(2)
29.6895(3)
74.934(1)
87.333(1)
77.902(1)
4479.8(1)
8
10.5634(1)
13.6415(1)
17.5285(2)
105.828(1)
101.72(1)
91.30(1)
2371.2(1)
4
12.1200(2)
11.8640(2)
13.9670(2)
90
111.486(1)
90
1868.8(1)
2
1.961
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
3
,
Z
Dcalc (g cm−3
)
2.000
102.7
3360
1.862
68.66
2424
1.880
66.03
1296
v (Mo–Ka) (cm−1
F(000)
)
80.08
1060
Measured reflections
Unique reflections
Absorption correction
136 725
6591 [Rint=0.065]
DELABS
87 211
39 356
79 520
17 040 [Rint=0.034]
DELABS
0.45/0.89
1095
R1=0.0298,
wR2 a=0.0740
–
10 044 [Rint=0.029]
DELABS
0.61/0.88
559
R1=0.0237,
wR2 a=0.0544
–
10 003 [Rint=0.0474]
DELABS
0.224/0.688
467
R1=0.0248,
wR2 a=0.0673
0.001(3)
Tmin/Tmax
0.316/0.750
Refined parameters
Final R values [I]2|(I)]
578
R1=0.0302, wR2 a=0.0742
Absolute structure parameter Twin refinement,
BASF=0.4988
a, b
zfin(max/min) (e A
0.0381, 26.65
2.65/−2.07
0.0348, 13.59
1.71/−1.60
0.00, 4.60
1.28/−0.79
0.00, 0.00
1.93/−1.90
−3
,
)
a wR2={[w(F2o−Fc2)2]/[w(Fo2)2]}1/2; w=1/[|2(Fo2)+(ap)2+bp]; p=(Fo2+2F2c)/3.
2.4. [Ph3PAu(2-SPym-4-NH2)] (3)
2.3. [Et3PAu(2-SPym-4-NH2)] (2)
An MeOH suspension (5 ml) of 4-amino-2-pyrim-
idine-thiol (26 mg, 0.20 mmol) and sodium methoxide
An MeOH suspension (5 ml) of 4-amino-2-pyrim-
idine-thiol (51 mg, 0.40 mmol) and sodium methoxide
(24 mg, 0.44 mmol) was added dropwise to a stirred
solution of [Et3PAuCl] (140 mg, 0.40 mmol) in CH2Cl2
(15 ml). After stirring for 2 h, all solvent was removed
and the crude product dissolved in CH2Cl2 (30 ml) and
filtered through diatomaceous earth to remove NaCl.
After concentration of the solution to ca. 10 ml, pen-
tane (20 ml) was carefully added to precipitate a color-
less solid. This was washed with pentane (20 ml)
and dried. Yield: 68% (120 mg). MS (FAB) m/z=
756, 43% [2M−SR]+, 442, 100% [M]+, 315, 68%
[M−SR]+. 31P{1H}-NMR (CD2Cl2, ppm): l 37.5.
13C{1H}-NMR (CD2Cl2, ppm): l 8.8 (s, CH3), 18.1
(d, CH2, JCP=33.2 Hz), 99.6 (s, C5), 155.4 (s, C6),
Fig. 1. Molecular structures of the four independent molecules in the
asymmetric unit of crystals of compound 2. (ORTEP, 50% probability
ellipsoids; only the hydrogen atoms of the amino group are shown
1
161.9 (s, C4), 179.6 (s, C2). H-NMR (CD2Cl2, ppm): l
1.23 (dt, 9H, CH3, JHP=18.3 Hz, JHH=7.7 Hz), 1.87
(dq, 6H, CH2, JHP=9.65 Hz, JHH=7.7 Hz), 4.71 (s,
2H, NH2), 6.03 (d, 1H, H5, JHH=5.7 Hz) 7.82 (d, 1H,
H6, JHH=5.7 Hz). Anal. Calc. for C10H19AuN3PS: C,
27.22; H, 4.34; N, 9.52. Found: C, 27.15; H, 4.22; N,
9.53%.
,
with arbitrary radii.) Selected bond lengths (A) and angles (°):
Au1ꢀP1, 2.250(3); Au1ꢀS1, 2.291(3); P1ꢀAu1ꢀS1, 173.6(1);
Au1ꢀS1ꢀC11, 106.5(3); Au2ꢀP2, 2.250(3); Au2ꢀS2, 2.295(3);
P2ꢀAu2ꢀS2, 171.6(1); Au2ꢀS2ꢀC21, 106.8(3); Au3ꢀP3, 2.260(3);
Au3ꢀS3 2.307(2); P3ꢀAu3ꢀS3, 175.6(1); Au3ꢀS3ꢀC31, 103.8(3);
Au4ꢀP4 2.252(3); Au4ꢀS4, 2.300(3); P4ꢀAu4ꢀS4, 174.7(1).

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J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
[M]+, 460, 37% [M−SR]+. 31P{1H}-NMR (CD2Cl2,
ppm): l 38.1. 13C{1H}-NMR (CD2Cl2, ppm): l 99.9 (s,
C5), 129.1 (d, o/m-C6H5, JCP=12.7 Hz), 129.8 (d,
ipso-C6H5, JCP=56.9 Hz), 131.6 (d, p-C6H5, JCP=2.3
Hz), 134.2 (d, o/m-C6H5, JCP=12.7 Hz), 155.4 (s, C6),
1
162.1 (s, C4), 179.3 (s, C2). H-NMR (CD2Cl2, ppm): l
4.62 (s, 2H, NH2), 6.03 (d, 1H, H5, JHH=5.7 Hz)
7.45–7.64 (m, 15H, C6H5) 7.86 (d, 1H, H6, JHH=5.7
Hz). Anal. Calc. for C22H19AuN3PS·0.5CH2Cl2: C,
43.04; H, 3.21; N, 6.69. Found: C, 42.68; H, 3.00; N,
6.23%.
2.5. [Ph2PyPAu(2-SPym-4-NH2)] (4)
An MeOH suspension (5 ml) of 4-amino-2-pyrim-
idine-thiol (26 mg, 0.20 mmol) and sodium methoxide
(12 mg, 0.22 mmol) was added dropwise to a stirred
solution of [Ph2PyPAuCl] (100 mg, 0.20 mmol) in
CH2Cl2 (15 ml). After stirring for 2 h, all solvent was
removed and the crude product dissolved in CH2Cl2 (20
ml) and filtered through diatomaceous earth to remove
NaCl. After concentration of the solution to ca. 10 ml,
pentane (20 ml) was carefully added to precipitate a
colorless solid. This was washed with pentane (20 ml)
and dried. Yield: 76% (90 mg). MS (FAB) m/z=587,
100% [M]+, 460, 40% [M−SR]+, 324, 4% [AuSR]+.
Fig. 2. Illustration of the connectivity of the individual monomers via
hydrogen bonding projected down the b axis of the unit cell.
31P{1H}-NMR (CD2Cl2, ppm):
(CD2Cl2, ppm): l 4.77 (s, 2H, NH2), 6.06 (d, 1H, H5,
HH=5.8 Hz) 7.5, 7.8 (m×2, 12H, C6H5+C5H4N),
7.89 (d, 1H, H6, JHH=5.8 Hz), 8.07 (t, 1H, H4/5Py,
HH=7.7 Hz), 8.79 (d, 1H, H3/6Py, JHH=7.7 Hz).
l
37.1. 1H-NMR
J
J
Anal. Calc. for C21H18AuN4PS·0.75CH2Cl2: C, 40.18;
H, 3.02; N, 8.62. Found: C, 40.23; H, 3.23; N, 8.31%.
2.6. [(2,6-Me2C6H3NC)Au(2-SPym-4-NH2)] (5)
An MeOH solution (5 ml) of 4-amino-2-pyrimidine-
thiol (35 mg, 0.28 mmol) and sodium methoxide (16
mg, 0.30 mmol) was added dropwise to a stirred solu-
tion of [(2,6-Me2C6H3NC)AuCl] (100 mg, 0.28 mmol)
in CH2Cl2 (15 ml). A yellow coloration appeared which
dispersed after stirring for 1 h. All solvent was removed
and the crude product dissolved in CH2Cl2 (20 ml) and
filtered through diatomaceous earth to remove NaCl.
After concentration of the solution to ca. 10 ml, pen-
tane (20 ml) was carefully added to precipitate a color-
less solid. This was washed with pentane (20 ml) and
dried. Yield: 66% (63 mg). IR (Nujol/KBr, cm−1):
w(CN)=2201. MS (FAB) m/z=782, 11% [2M−SR]+,
456, 100% [M]+, 324, 26% [M−CNX]+. 1H-NMR
(CD2Cl2, ppm): l 2.40 (s, 6H, CH3), 4.75 (s, 2H, NH2),
6.11 (d, 1H, H5, JHH=6.2 Hz), 7.11 (d, 2H, H3,5C6H3,
Fig. 3. Molecular structures of the four independent molecules in the
asymmetric unit of crystals of compound 3. (ORTEP, 50% probability
ellipsoids; only the hydrogen atoms of the amino groups are shown
,
with arbitrary radii.) Selected bond lengths (A) and angles (°):
Au1ꢀP1, 2.262(1); Au1ꢀS1, 2.308(1); P1ꢀAu1ꢀS1, 175.31(4),
Au1ꢀS1ꢀC11, 102.6(1); Au2ꢀP2, 2.249(1); Au2ꢀS2, 2.307(1);
P2ꢀAu2ꢀS2, 178.96(4); Au2ꢀS2ꢀC21, 99.3(1); Au3ꢀP3, 2.260(1);
Au3ꢀS3, 2.306(1); P3ꢀAu3ꢀS3, 179.04(4); Au3ꢀS3ꢀC31, 101.9(1);
Au4ꢀP4, 2.256(1); Au4ꢀS4, 2.303(1); P4ꢀAu4ꢀS4, 179.85(4);
Au4ꢀS4ꢀC41, 100.4(1). The asymmetric unit contains two
dichloromethane solvent molecules.
(12 mg, 0.22 mmol) was added dropwise to a stirred
solution of [Ph3PAuCl] (100 mg, 0.20 mmol) in CH2Cl2
(15 ml). After stirring for 2 h, all solvent was removed
and the crude product dissolved in dichloromethane (20
ml) and filtered through diatomaceous earth to remove
NaCl. After concentration of the solution to ca. 10 ml,
Et2O (20 ml) was carefully added to precipitate a
colorless solid. This was washed with Et2O (20 ml) and
dried. Yield: 68% (81 mg). MS (FAB) m/z=586, 67%
J
HH=7.7 Hz), 7.27 (t, 1H, H4C6H3, JHH=7.7 Hz), 7.80
(d, 1H, H6,
HH=6.2 Hz). Anal. Calc. for
J
C13H13AuN4S·CH2Cl2: C, 31.18; H, 2.80; N, 10.39.
Found: C, 31.44; H, 2.61; N, 10.10%.

J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
317
Fig. 4. The molecules of compound 3 are connected via hydrogen bonding to form strings resembling four-bladed paddle-wheels running parallel
to the a axis of the cell as shown in this projection. The columns of triarylphosphines are interlocked to fill the space. Voids remaining in this
packing are filled by the solvent molecules (not shown).
2.7. (dppm)[Au(2-SPym-4-NH2)]2 (6)
C42H36Au2FeN6P2S2: C, 42.02; H, 3.02; N, 7.00. Found:
C, 41.61; H, 3.00; N, 6.90%.
An MeOH suspension (5 ml) of 4-amino-2-pyrim-
idine-thiol (30 mg, 0.24 mmol) and sodium methoxide
(14 mg, 0.26 mmol) was added dropwise to a stirred
solution of [(dppm)(AuCl)2] (100 mg, 0.12 mmol) in
CH2Cl2 (15 ml). After stirring for 2 h, all solvent was
removed and the solid triturated in water (25 ml). The
colorless product was filtered, washed with water (20
ml), MeOH (10 ml) and pentane (20 ml) and dried.
Yield: 67% (83 mg). MS (FAB) m/z=905, 100% [M−
SR]+, 580, 7% [(dppm)Au]+. 31P{1H}-NMR (CD2Cl2,
ppm): l 32.1. Anal. Calc. for C33H30Au2N6P2S2: C,
38.46; H, 2.93; N, 8.15. Found: C, 38.86; H, 3.08; N,
8.12%.
2.9. [(Ph3PAu)2(2-SPym-4-NH2)]BF4 (8)
The oxonium salt [(Ph3PAu)3O]BF4 (100 mg, 0.068
mmol), amino-2-pyrimidine-thiol (12.9 mg, 0.102
mmol) and NaBF4 (20 mg, 0.182 mmol) were dissolved
2.8. (dppf )[Au(2-SPym-4-NH2)]2 (7)
An MeOH suspension (5 ml) of 4-amino-2-pyrim-
idine-thiol (25 mg, 0.20 mmol) and sodium methoxide
(12 mg, 0.22 mmol) was added dropwise to a stirred
solution of [(dppf)(AuCl)2] (100 mg, 0.10 mmol) in
CH2Cl2 (15 ml). After stirring for 2 h, the solvent
volume was reduced until precipitation of the pale
orange product had occurred. This was washed with
water (10 ml), methanol (10 ml) and pentane (20 ml)
and dried. Yield: 87% (102 mg). MS (FAB) m/z=1075,
100% [M−SR]+, 751, 17% [(dppf)Au]+. 31P{1H}-
NMR (MeOH/CD2Cl2, ppm): l 30.0. Anal. Calc. for
Fig. 5. Molecular structures of the two independent complex
molecules and two dichloromethane molecules in the asymmetric unit
of crystals of compound 4. (ORTEP, 50% probability ellipsoids, hydro-
,
gen atoms with arbitrary radii.) Selected bond lengths (A) and angles
(°): Au1ꢀP1, 2.2610(8); Au1ꢀS1, 2.3083(8); P1ꢀAu1ꢀS1, 170.89(3);
Au1ꢀS1ꢀC41, 105.0(1); Au2ꢀP2, 2.2536(8); Au2ꢀS2, 2.3068(8);
P2ꢀAu2ꢀS2, 175.18(3); Au2ꢀS2ꢀC81, 102.0(1).

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42.46; H, 3.03; N, 3.71. Found: C, 42.17; H, 2.92; N,
3.69%.
2.10. X-ray crystallography
Specimens of suitable quality and size of compounds
2–4 and 6 were mounted on the ends of quartz fibers in
F06206R oil and used for intensity data collection on a
Nonius DIP2020 diffractometer, employing graphite-
monochromated Mo–Ka radiation. The structures were
solved by a combination of direct methods (SHELXS-97)
and difference-Fourier syntheses and refined by full-
matrix least-squares calculations on F2
(SHELXL-97).
The thermal motion was treated anisotropically for all
non-hydrogen atoms. All CꢀH atoms were calculated
and allowed to ride on their parent atoms with fixed
isotropic contributions, whereas all NꢀH atoms were
located. Further information on crystal data, data col-
lection and structure refinement are summarized in
Table 1. Important interatomic distances and angles are
shown in the corresponding figure captions.
Fig. 6. Connectivity pattern for complex 4 showing the bifurcated
double-bridging between a pair of symmetry-related molecules (with
Au2 as the metal centers) and the single-bridging with neighboring
molecules (with Au1 as the metal centers). The extension of this
pattern leads to a three-dimensional network.
3. Results and discussion
Complexes 1–4 and 6–8 were isolated as the only
phosphine-containing species from reaction of the
(phosphine)gold(I) halide starting materials with 4-
amino-2-pyrimidine-thiol, as indicated by the singlet
resonances observed in the 31P-NMR spectra. The em-
pirical composition of the products was confirmed by
microanalysis and FAB mass spectrometry. The molec-
ular ion was generally the fragment with the highest
m/z value, however, in some cases a fragmentation
attributable to [2M-(2-SPym-4-NH2)] was observed. As
expected, the 4-amino-2-pyrimidine-thiolate ligand gave
Fig. 7. Molecular structure of the independent dinuclear complex 6
and a dimethylformamide molecule in the asymmetric unit of the
crystals. (ORTEP, 50% probability ellipsoids, hydrogen atoms with
1
rise to three resonances in the H-NMR spectrum. A
,
arbitrary radii.) Selected bond lengths (A) and angles (°): Au1ꢀAu2,
singlet at 4.7 ppm was assigned to the amino group,
while the pyrimidine protons were represented by dou-
blet resonances at 6.0 and 7.8 ppm (JHH=5.7 Hz).
Four singlets were observed in the 13C-NMR spectrum
for the 4-amino-2-pyrimidine thiolate ligand at 179.3
(C2), 162.1 (C4), 155.4 (C6) and 99.9 (C5) ppm. The only
one of these to display a shift from the free ligand
resonance is that for C6. Characteristic spectroscopic
data were obtained for the PR3, dppm and dppf lig-
ands. The presence of the 2,6-dimethylphenylisocyanide
ligand in the complex [(2,6-C6H3Me2NC)Au(2-SPym-4-
3.3317(2); Au1ꢀP1, 2.261(1); Au1ꢀS1, 2.309(1); P1ꢀAu1ꢀS1,
168.25(4); Au1ꢀS1ꢀC11, 103.7(1); Au2ꢀP2, 2.2591(9); Au2ꢀS2,
2.3052(9); P2ꢀAu2ꢀS2, 175.66(4); Au2ꢀS2ꢀC21, 106.3(1); P1ꢀC1ꢀP2,
115.6(2); Au1ꢀP1ꢀC1, 119.2(2); Au2ꢀP2ꢀC1, 111.3(1).
in a mixture of CH2Cl2 (15 ml) and MeOH (5 ml). The
reaction mixture was stirred for 2 h and all solvent
removed. The crude product was dissolved in CH2Cl2
(15 ml) and filtered through diatomaceous earth. Di-
ethyl ether (20 ml) was added to precipitate the color-
less product which was washed with Et2O (20 ml) and
dried. Yield: 87% (110 mg). MS (FAB) m/z=1045,
100% [M]+, 782, 26% [M−PPh3]+, 721, 37%
[Au(PPh3)2]+, 586, 19% [M−AuPPh3]+, 459, 90%
1
NH2)] (5) was confirmed by resonances in the H-NMR
spectrum attributed to the methyl groups (s, 2.40 ppm)
and meta/para aryl protons (7.11 and 7.27 ppm, JHH
=
7.7 Hz). A strong w(CN) absorption was observed in
the infrared spectrum at 2201 cm−1. Compounds 2–4
provided suitable single crystals for structural studies to
be undertaken. These revealed hydrogen-bonding net-
works of considerable complexity.
1
[AuPPh3]+. 31P{1H}-NMR (CD2Cl2, ppm): l 32.3. H-
NMR (CD2Cl2, ppm): l 4.91 (s, 2H, NH2), 6.60 (d, 1H,
H5, JHH=6.4 Hz), 7.11, 7.57 (m×2, 31H, C6H5+
H3,5C6H3). Anal. Calc. for C40H34Au2BF4N3P2S: C,

J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
319
The dinuclear species (dppm)[Au(2-SPym-4-NH2)]2
(6) and (dppf)[Au(2-SPym-4-NH2)]2 (7) proved to be
highly insoluble in di- and trichloromethane, tetrahy-
drofuran, methanol and in acetone, once precipitated
from the reaction mixture. Their composition was given
by microanalysis. The major ions in the FAB mass
spectra were assigned to fragmentation through loss of
1
one thiolate ligand. 31P- and H-NMR spectra of com-
pound 6 were recorded in dimethylfomamide. A singlet
resonance at 32.1 ppm in the 31P-NMR spectrum indi-
Fig. 8. Hydrogen bonding pattern in a double-strand of complex molecule 6.
Fig. 9. (a) Projection parallel to a corrugated sheet formed by aggregation of complex molecule 6. (b) Interlocking (indenting) of these sheets.

320
J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
Table 2
Hydrogen bonds in compounds 2–4 and 6
DꢀH
H···A
DꢀH···A
D···A
A
Symmetry
Compound 2
N13ꢀH131
N13ꢀH132
N23ꢀH231
N23ꢀH232
N33ꢀH331
N33ꢀH332
N43ꢀH431
N43ꢀH432
0.95
1.05
0.69
0.89
0.94
0.89
0.85
1.11
2.17
2.05
2.31
2.15
2.18
2.19
2.11
1.89
147.3
147.3
163.1
168.7
140.4
149.7
167.8
155.4
3.01
2.99
2.97
3.02
2.96
2.99
2.94
2.94
N22
N32
N41
N12
N11
N42
N21
N31
−X−0.5, Y−0.5, Z+0.5
X+0.5, Y, Z
X, Y, Z
−X−0.5, Y+0.5, Z−0.5
X−0.5, −Y−1.5, Z
X, Y, Z
X+0.5, −Y−1.5, Z
X, Y, Z
Compound 3
N13ꢀH131
N13ꢀH132
H23ꢀH231
N23ꢀH232
0.85
0.85
0.90
0.80
2.23
2.20
2.18
2.33
176.1
174.5
173.3
161.2
3.08
3.05
3.07
3.81
N12
N41
N22
N32
−X, −Y+2, −Z+1
−X, −Y+1, −Z+1
−X+1, −Y+2, −Z
−X+1, −Y+2, −Z
Compound 4
N47ꢀH47A
N47ꢀH47B
N87ꢀH87A
N87ꢀH87B
0.88
0.88
0.88
0.88
2.21
2.18
2.14
2.15
162.4
155.7
175.7
161.1
3.06
3.00
3.02
3.00
N42
N86
N82
N46
−X, −Y, −Z+1
−X+1, −Y+1, −Z+1
−X+3, −Y+1, −Z+1
−X+2, −Y+1, −Z+1
Compound 6
N13ꢀH131
N13ꢀH132
N23ꢀH231
N23ꢀH232
0.76
0.71
0.99
0.94
2.26
2.46
1.92
2.17
167.5
151.3
172.4
172.3
2.99
3.09
2.90
3.05
N11
N22
N21
N12
−X+1, Y+0.5, −Z+2
X, Y+1, Z
−X+2, −Y−0.5, −Z+2
X, Y−1, Z
cated a symmetrical molecule, and a crystallographic
study was able to confirm that it adopts the ‘A-frame’
geometry observed for the vast majority of
(dppm)gold(I) species [19]. The molecular structure and
that of the hydrogen-bonding network around the 2-
SPym-4-NH2 ligands are discussed in the Section 3.1. It
proved possible to obtain a 31P-NMR spectrum of
compound 7 only from the reaction mixture before
precipitation and this displayed a singlet resonance at
30.0 ppm. Thereafter it became insoluble in all common
laboratory solvents including dimethylformamide and
dimethylsulfoxide.
Reaction of the oxonium salt [(Ph3PAu)3O]BF4 with
2-amino-4-pyrimidine-thiol in the presence of NaBF4
led smoothly to the isolation of the dinuclear complex
[(Ph3PAu)2(2-SPym-4-NH2)]BF4 (8) in excellent yield.
The same product can be obtained by treatment of 3
with Ph3PAuBF4 prepared in situ though the one-step
route leads to better yields. A molecular ion at m/z=
1045 in 100% abundance is present in the FAB mass
spectrum along with fragments due to loss of phos-
phine. No fragment attributable to [Ph3PAu(2-SPym-4-
NH2)]+ is observed.
phine (4) complexes. None of these three examples
shows aurophilic interaction between the gold(I) centers
in the crystal. The compounds are all aggregated solely
via extensive hydrogen bonding networks. The absence
of metallophilic interactions is probably not due to
steric shielding of the metal atoms by the tertiary
phosphines and the thiolate ligands. Several other tri-
ethyl- and triphenylphosphine complexes were found to
aggregate via short gold–gold contacts, where this
mode of aggregation is not in competition with other
intermolecular interactions. Quite frequently hydrogen
bonding was identified as the overruling competitor,
and the dominance of hydrogen bonding appears to be
a general feature also in the present series. Arene
stacking is also known to contribute considerably to the
lattice organization of (arylphosphine)gold(I) com-
plexes, but there is no evidence for this type of interac-
tion in the present structures (3 and 4). Details are
summarized in the following brief discussion.
Crystals of triethylphosphine complex 2 are or-
thorhombic, space group Pna21, with Z=16 molecular
units in its large unit cell. The asymmetric unit contains
no less than four independent molecules which are
similar in their configurational and conformational de-
tails (Fig. 1). The AuꢀP and AuꢀS distances and the
PꢀAuꢀS angles are all as expected from standard refer-
ence data with only minor variations. Interactions be-
tween neighboring molecules are established through
3.1. Discussion of structural results
Of the small series of title compounds 1–5 structural
data are available for the triethylphosphine (2),
triphenylphosphine (3) and diphenyl(2-pyridyl)phos-

J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
321
of which is shown in Fig. 7. The intramolecular AuꢀAu
the aminopyrimidinethiolate ligands with the amino
groups as the proton donor and the pyrimidine ring
nitrogen atoms as the proton acceptors. Through two
of these parallel interactions, employing one of the two
amino hydrogen atoms of each partner molecule and
the pyrimidine nitrogen atoms adjacent to the amino
groups the usual bifurcated pairing is generated (cf. e.g.
center of Fig. 6). The second hydrogen atom of the
same amino groups is attached to a donor atom (the
second pyrimidine ring nitrogen atom) of another
neighbouring unit in different directions. In total, the
resulting complicated network is three-dimensional as
shown in a projection in Fig. 2.
,
distance is 3.3317(2) A, well in the range of standard
aurophilic bonding. The fact that the gold atoms are
drawn together is in fact obvious from the significant
bending of the P1ꢀAu1ꢀS1 unit [168.25(4)°] which devi-
ates by 11.75° from linearity. The angle P2ꢀAu2ꢀS2 is
reduced to 175.66(4)°. There are sharp bendings at the
thiolate sulfur atoms [Au1ꢀS1ꢀC11, 103.7(1)°;
Au2ꢀS2ꢀC21, 106.3(1)°] and very different torisonal
angles P1ꢀAu1ꢀS1ꢀC11 [73.4(2)°] and P2ꢀAu2ꢀS2ꢀC21
[−120.8(5)°]. This leads to two different connectivities
through hydrogen bonding in several directions.
The dinuclear complexes are arranged in strings in
which the molecules are intimately connected via the
bifurcated type of hydrogen bonding illustrated already
above for other complexes of this type. In this bonding
one hydrogen atom of each amino group and the
adjacent nitrogen atom of the pyrimidine ring are en-
gaged. These strings of molecules are associated to give
double-stands through hydrogen bonding originating
from the second hydrogen atom at one of the two
amino groups of each dinuclear complex and reaching
out to the second ring nitrogen of a pyrimidine unit in
the neighboring string. The second hydrogen atom of
the second amino group finally reaches out to a pyrim-
idine nitrogen atom of another double-strand (Fig. 8).
Through this connectivity corrugated sheets are pro-
duced (Fig. 9a), which are staked in such a way that
efficient space filling is reached through intimate indent-
ing of the columns of phenyl groups covering the sheets
above and below (Fig. 9b).
A survey of the above structures (2–4, 6) shows that
the packing of the molecules is governed solely by
hydrogen bonding. The hydrogen bonds in these com-
plexes are listed in Table 2. Intermolecular aurophilic
bonding or arene stacking play no role. However, the
connectivity varies quite strongly indicating that there
is considerable flexibility in the hydrogen-bonding net-
work. The framework can thus be easily adjusted to the
sub-structure of the tertiary phosphine ligand which is
to be accommodated in such a way that space-filling is
most efficient. The absolute dominance of hydrogen
bonding in the present structures is probably due to the
multifunctionality of the amino-pyrimidine system
which can adapt to a manifold of connectivity patterns
and thus optimize the packing energy of the lattice.
Crystals of the triphenylphosphine complex 3 grown
from dichloromethane solution are triclinic, space
(
group P1 with Z=8 complex molecules and four sol-
vent molecules in the unit cell. The asymmetric unit
thus again contains no less than four independent
molecules with similar molecular geometries and two
dichloromethane molecules as shown in Fig. 3. The
molecules are aggregated via hydrogen bonds of a
similar type as described for compound 2, but a differ-
ent connectivity pattern leads to strings resembling
four-bladed paddle-wheels running parallel to the x axis
and mutually indented as shown in Fig. 4.
Crystals of the diphenyl(2-pyridyl)phosphine com-
plex 4 obtained from dichloromethane solution are also
(
triclinic, space group P1 with Z=4 complexes and four
dichloromethane molecules in the unit cell. The asym-
metric unit contains two independent complex
molecules (and two solvent molecules) which are shown
in Fig. 5. The molecular structures are similar to those
of the triphenylphosphine analogues (above) because
the PPh3 unit has about the same steric requirements as
the Ph2PyP unit. There is no conspicuous preference in
the orientation of the pyridyl rings as compared to the
phenyl rings. Optimum space filling appears to be the
guiding principle. The typical bifurcated connectivity of
two symmetry-equivalent molecules and the attachment
of this unit to neighboring molecules to give an ex-
tended structure is shown in Fig. 6.
The dinuclear dppm complex 6 has two gold centers
held in close proximity, and therefore it is to be ex-
pected that these molecules feature short intramolecular
aurophilic interactions. These interactions require a cis-
or Z-conformation regarding the orientation of the two
diphenylphosphino groups at the bridging methylene
unit, but this has been shown to be the standard
conformation for all (dppm)digold complexes. The
crystal structure of 6 confirms this assumption.
4. Conclusions
Crystals of the dppm compound 6 obtained from
dimethylformamide are monoclinic, space group P21
with Z=2 complex molecules and two solvent
molecules in the unit cell. The asymmtric unit has one
independent dinuclear complex molecule, the structure
The auration of polyfunctional ligands provides a
useful means to study the combined use of hydrogen-
bonding and aurophilic interactions in the design of
supramolecular networks. Due to the amino protons
and nitrogen atoms of the pyrimidine ring, 4-amino-2-

322
J.D.E.T. Wilton-Ely et al. / Journal of Organometallic Chemistry 643–644 (2002) 313–323
(e) J.M. Forward, D. Bohmann, J.P. Fackler Jr., R.J. Staples,
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mercaptopyrimidine has proved a highly suitable ligand
with which to probe the design of hydrogen-bonding
interactions. These results open up the possibility of
employing more highly functionalized ligands to create
systems of ever greater complexity based on gold–gold
contacts and hydrogen bonding.
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Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 172601–172604 for com-
pounds 2–4 and 6, respectively. Copies of this informa-
tion may be obtained free of charge from The Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK
(Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
(i) J.D.E.T. Wilton-Ely, A. Schier, N.W. Mitzel, H. Schmid-
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Support of this work by the Deutsche Forschungsge-
meinschaft, the Volkswagenstiftung, the Alexander von
Humboldt Stiftung (J.D.E.T.W.-E.), and by the Fonds
der Chemischen Industrie is gratefully acknowledged.
The authors are also indebted to Degussa AG and
Heraeus GmbH for the donation of chemicals.
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