Mono- and binuclear gold(I) amido compounds of purine derivatives

Article abstract of DOI:10.1515/znb-2004-11-1234

A series of neutral dinuclear and mononuclear gold(I) complexes with phosphine and N-bonded 9H-purin-9-ate or 9H-purin-6-ylamine-9-ate have been synthesised under basic conditions and characterised by gHSQC, ¹H, ¹³C gHMQC and ¹H detected ¹H,¹⁵N gHMQC experiments in addition to ESI-MS and IR spectroscopy. Intermolecular aurophilic interactions are present in the structures of polymeric 1,2-bis(diphenylphosphine)ethane(9H-purin-9-ate)gold(I) 1, (3.1641(4) ?) and 1,3-bis(diphenylphosphine)propane(9H-purin-9-ate)gold(I) 3, (3.52 ?). The N-Au-P angle in 1 is exceptionally small (166.3(1)?). Intramolecular aurophilic interaction (3.63 ?) complemented by hydrogen bonding dictates the non-oligomeric structure of 1,3-bis(diphenylphosphine)propane(9H-purin6- ylamin-9-ate)gold(I) (7). Dimeric aurophilic interactions appear in the structure of (tributylphosphine)(9H-purin-9-ate)gold(I) (11) (3.2311(7) ?), while the structure in the other mononuclear compound, (triphenylphosphine)(9H-purin-9-ate)gold(I) (9) is organised by Au...N-interactions.

Full text of DOI:10.1515/znb-2004-11-1234

Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
Ulrike E. I. Horvath, Stephanie Cronje, Jean M. McKenzie, Leonard J. Barbour,
and Helgard G. Raubenheimer
Department of Chemistry, University of Stellenbosch,
Private Bag X1, Matieland, 7602, Stellenbosch, South Africa
Reprint requests to Prof. Helgard G. Raubenheimer. Fax: +27 21 8083849. E-mail: hgr@sun.ac.za
Z. Naturforsch. 59b, 1605 – 1617 (2004); received September 27, 2004
Dedicated to Professor Hubert Schmidbaur on the occasion of his 70th birthday in recognition of his
continuing contributions to inorganic and organometallic chemistry
A series of neutral dinuclear and mononuclear gold(I) complexes with phosphine and N-bonded
9H-purin-9-ate or 9H-purin-6-ylamine-9-ate have been synthesised under basic conditions and char-
acterised by gHSQC, 1H,13C gHMQC and 1H detected 1H,15N gHMQC experiments in addition
to ESI-MS and IR spectroscopy. Intermolecular aurophilic interactions are present in the structures
˚
of polymeric 1,2-bis(diphenylphosphine)ethane(9H-purin-9-ate)gold(I) 1, (3.1641(4) A) and 1,3-
˚
bis(diphenylphosphine)propane(9H-purin-9-ate)gold(I) 3, (3.52 A). The N-Au-P angle in 1 is excep-
◦
˚
tionally small (166.3(1) ). Intramolecular aurophilic interaction (3.63 A) complemented by hydro-
gen bonding dictates the non-oligomeric structure of 1,3-bis(diphenylphosphine)propane(9H-purin-
6-ylamin-9-ate)gold(I) (7). Dimeric aurophilic interactions appear in the structure of (tributylphos-
˚
phine)(9H-purin-9-ate)gold(I) (11) (3.2311(7) A), while the structure in the other mononuclear com-
pound, (triphenylphosphine)(9H-purin-9-ate)gold(I) (9) is organised by Au...N-interactions.
Key words: Gold(I) Complexes, Aurophilic Interactions, Amido Ligands, 9H-Purine, DNA Base
Pharmacological application of gold(I) compounds fects of the ligands on gold(I), steric effects and pack-
in the treatment of rheumatoid arthritis and their poten- ing forces are actively pursued and have propelled au-
tial activity as anticancer, antiviral and antimicrobial rophilic interactions into the domain of supramolecular
agents provide powerful motivation for the continued chemistry [9, 13 – 16].
interest in the bonding of biologically active molecules
to gold(I) [1 – 5].
In pursuit of the above fields of interest we investi-
gated and now report the preparation and characterisa-
tion of neutral dinuclear and mononuclear gold(I) com-
plexes with phosphine and N-bonded 9H-purin-9-ate
or 9H-purin-6-ylamine-9-ate ligands under basic con-
ditions.
The prevalence of five-membered nitrogen-con-
taining ring systems and thiolate bonding sites in
biologically active molecules, identifies them as
ideal candidates for enquiry as far as bonding to
gold(I) is concerned. Coordination of gold(I) to 8-
mercaptotheophylline [6], xanthine, xanthine deriva-
tives [7], phthalimide and ribovlavin [8] has been
explored. Diphosphines and phosphinegold(I) com-
pounds exhibit anticancer activity [3]. An interest in
Results and Discussion
Syntheses and characterisation
Deprotonated (NaOH) purine dissolved in
the bonding of gold(I) to thiolate functions has re- methanol, reacted with the appropriate gold start-
sulted in a thorough investigation of mono- and phos- ing material to yield complexes 1 – 3, 10 and 11
phine(dithiolate)gold(I)compounds [9]. Although sev- (Scheme 1). The analogous purin-6-ylamine anion
eral amido complexes of gold(I) have been charac- was prepared in DME by deprotonation with NaOH in
terised [4, 10 – 12], the coordination of DNA bases or the presence of small amounts of water. Reaction of
purines to (phosphine)gold(I) compounds remains of this anion with chloro(phosphine)gold(I) complexes
interest.
gave the amido complexes 5 – 8, 12 and 13. Com-
Factors determining aurophilic interactions yield- plexes 4 and 9 did not form according to the first
ing dimers, oligomers and polymers, e.g. electronic ef- protocol, but the synthetic methodology followed for
c
0932–0776 / 04 / 1100–1605 $ 06.00 ꢀ 2004 Verlag der Zeitschrift fu¨r Naturforschung, Tu¨bingen · http://znaturforsch.com
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
fragments consisting of the target molecule and an ex-
tra gold phosphine unit as well as a fragment represent-
ing Au(phosphine)2.
Spectroscopy
The IR spectra of all purin-9-ate-containing com-
pounds (1 – 4, 9 – 11) show no ν(NH) stretching band
at 3432 cm−1. This suggests that the ionisable pro-
ton on the nitrogen atom of the five membered ring in
purine has been substituted by (phosphine)gold(I) or
(diphosphine)digold(I) moieties. The ν(C=N) stretch-
ing frequency at 1570 cm−1 in purine appears at higher
wavenumbers in the gold complexes while all other
bands show no significant change from their position
in purine.
The detection of the νs(NH2) and νas(NH2) stretch-
ing bands excludes coordination of the gold to purin-
6-ylamine-9-ate via the amino group. The very strong
ν(NH2) bending mode of all purin-6-ylamine-9-ate-
containing complexes (5 – 8, 12 and 13) appears at
1633– 1674 cm−1. The absence of bands at ca. ν =
3432 cm−1 suggests substitution of H(9) by (phos-
phine)gold(I) or (diphosphine)digold(I) units.
Scheme 1. Gold(I) complexes of 9H-purin-9-ate (1 – 4,
9 – 11) and 9H-purin-6-ylamine-9-ate (5 – 8, 12 – 13).
The absence of signals for H(9) (δ = −13) in the
1H NMR spectra of all compounds, again indicates an-
ion formation and coordination to gold. Small changes
the purin-6-ylamine deprotonation was successful.
The unreacted gold starting materials were separated
by filtration from methanol suspensions of the crude
product. After in vacuo stripping of methanol, the
unreacted purine or purin-6-ylamine and formed NaCl
were removed from the product by repeated washing
with deoxygenated water. The new complexes are
stable in deoxygenated water and decompose slowly
in air. Compounds 1 and 8 are selectively soluble in a
1:1 mixture of CH2Cl2 and methanol, while 2, 6, 10
and 12 dissolve in water and all the other complexes
in methanol and organic solvents.
1
in chemical shift are observed in the H and 13C NMR
spectra of the new compounds in comparison to the
spectra of purine, purin-6-ylamine and the gold com-
plex starting materials. The largest change (δ = 9,
downfield) is observed for C(8) in the purin-6-ylamine-
9-ate compounds (5 – 8, 12 and 13). The assignments
of the signals observed for 9 and 13 were confirmed
1
by gHSQC and H,13C gHMQC experiments. In the
gHMQC spectrum of 9, H(8) shows two correlations
to the 13C dimension, one at δ = 160.4 and one at
δ = 134.7. As long-range coupling of H(8) with the
carbons in the phenyl rings is unlikely, this indicates
that one of the quatenary carbon atoms C(4) or C(5)
is obscured by the signal of the meta carbons on the
phenyl rings of PPh3 at δ = 134.7. H(6) also shows
correlations to the same 13C signals while H(2) only
correlates with the signal at δ = 160.4. Thus the lat-
The purin-9-ate compounds 3, 4 and 11 melt at
◦
temperatures lower than 100 C, while the purin-6-
ylamine-9-ate compounds, 5 and 8, and the purin-9-ate
monophosphine compounds, 9 and 10, melt at temper-
◦
atures above 150 C. All other compounds decompose
on heating.
The molecular ions are not observed in the ESI mass ter signal at δ = 160.4 can be assigned to C(4) and
spectra of these compounds. All complexes that con- the one at δ = 134.7 to C(5), the bridge carbon on the
tain diphosphine ligands (1 – 8) show m/z-values rep- imine side of the five-membered ring in the purin-9-
resenting the combined diphosphine, two gold atoms ate ligand. A carbon peak at δ = 126.6 tentatively as-
and either a purine or purin-6-ylamine unit. The spec- signed by Rosopulos et al. [12], is due either to unre-
tra of the monophosphine compounds (9 – 13) contain acted purine or to the sodium salt of purine.
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
1607
The 31P NMR signals are shifted upfield by less than are broad. The signals for the bridge carbons (C(4) and
4.5 ppm upon coordination of the gold compounds to C(5)) in the purin-9-ate ligand and the other two car-
purin-9-ate or purin-6-ylamine-9-ate. The observation bon atoms in the six-membered ring (C2 and C6) of
that the phosphorus chemical shift in the diphosphine the purin-9-ate ligand in 9 – 11, are also slightly broad-
compounds becomes more positive as the number of ened.
The 13C NMR spectra of the new compounds dis-
play other unusual features. The phenyl rings of the
phosphine ligands in 1 and 5 contain magnetically in-
equivalent carbon atoms resulting in triplets for the
meta and ortho carbons (doublet of doublets with
JPC = JPC, 6 and 8 Hz). The magnetic inequiva-
lence is not unexpected based on the symmetry of
the molecule [18]. The para carbons appear as a sin-
glet and the ipso as a doublet, JPC = 60 Hz. The car-
bons in the phenyl rings of the rest of the compounds
appear as doublets (JPC = 13 (meta), 2.4 (para), 12
(ortho) and 62 (ipso) Hz). The methyl groups on the
phosphine ligands in compounds 2 and 6 also dis-
play magnetic inequivalence resulting in signals for an
AA’XX’ spin system. The same signal pattern is ob-
served for the bridging CH2 groups in 2 and 6, sug-
gesting magnetic inequivalence in these carbon atoms
as well. The carbon atoms in the bridge of the 1,2-
bis(diphenylphosphine)ethane ligands in 1 and 5 also
experience magnetic inequivalence resulting in com-
plicated multiplets.
In compounds that contain longer bridges (3, 4, 7
and 8) and in the P(n-Bu)3 compounds (11 and 13),
no magnetic inequivalence and no coupling (only a
slightly broadened signal) is detected for the second
carbon from the phosphine atom. The C-C-P angles of
3, 7 and 11 are all larger than the preferred 109◦ for
effective geminal coupling (vide infra) and the β car-
bon experiences only a small coupling resulting in a
slightly broader signal. With the bridge consisting of
three carbon atoms (3 and 7), the signal for the carbon
bonded to the phosphine appears as a doublet of dou-
blets (JPC = 38 and 10 Hz) as a result of coupling to
two P atoms. A doublet (JPC = 39 Hz) for the carbon
next to the P atom and a triplet (JPC = 14.6 Hz) for the
middle carbon atom are observed for the bridge of the
1,5-bis(diphenylphosphine)pentane ligands of 4 and 8.
Similar values are found for the carbons in the butyl
groups of 11 and 13 while the terminal carbon experi-
ences no coupling.
connecting carbons (n) increases (except when n = 2),
has been ascribed to small variations in the dihedral or
bond angles at the phosphorus atom as the length of the
alkyl backbone changes [7, 9].
1
The NH2 protons at δ = 7.09 in the H NMR of
purin-6-ylamine (CDCl3 solution) appear at δ = 5.78
in 13 (measured in CD2Cl2) and were not observed for
any of the other purin-6-ylamine-9-ate complexes (in
CD3OD).
The 15N chemical shifts of the nitrogen atoms of 1
were determined in a 1H detected 1H,15N gHMQC ex-
periment. The most shielded nitrogen at δ = −179.2
is assigned to the nitrogen atom bonded to the gold,
N(9). The nitrogen atoms in the six-membered ring
are less shielded (δ = −122.0, N(1) and δ = −130.6,
N(3)) than those in the five membered ring (δ =
−159.3, N(7) and N(9)) of the purin-9-ate ligand. The
15N chemical shifts of the nitrogen atoms of purin-6-
ylamine-9-ate in compound 13, were determined in the
same manner. The nitrogen bonded to gold (N(9)) is
again highly shielded at δ = −174.2. However, due to
the presence of the NH2 group, the nitrogens in the six-
membered ring are more shielded than those found in
1, appearing at δ = −150.3 (N(1)) and δ = −144.5
(N(3)). N(7) is slightly deshielded from the corre-
sponding nitrogen in 1, appearing at δ = −147.0. As
expected, the NH2 nitrogen appears significantly up-
field from the other nitrogens in the compound at δ =
−311.9. Attempts to locate the nitrogen atoms in the
other purinate compounds were not as successful and
only the two nitrogens in the six-membered rings of
1
2, 3 and 10 were detected. Since the H,15N gHMQC
1
indirect detection method is H detected, and the no-
tion that H(8) (pKa ∼ 7.3 [17]) is involved in some mi-
gratory process along the aromatic system in the five-
membered ring of the anionic ligand is not unreason-
able, the failure to detect the other nitrogen atoms is not
completely unexpected. Direct detection of 15N atoms
requires high sample concentration and extended data
collection times. This is not feasible when the solu-
bility of the compounds is low. The effects of migrat-
ing protons are also visible in the 13C NMR spectra of
some compounds. The signals for the carbons carrying
the NH2 group (C(6)) and the acidic hydrogen (C(8))
Molecular structure
The molecular structures of 1, 3, 7, 9 and 11 with
in the purin-6-ylamine-9-ate complexes 8, 12 and 13 the atom numbering schemes are depicted in Figs 1 – 5.
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
Fig. 1. Molecular structure of 1 show-
ing the numbering scheme. Only crystal-
lographically unique atoms are labelled.
Fig. 2. Molecular structure of 3.
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
1609
Fig. 3. Molecular structure
of 7.
Fig. 4. Molecular structure
of 9.
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
◦
˚
Table 1. Selected bond lengths [A] and angles [ ] of 1, 3, 7,
9 and 11.
1
3
7
9
11
Au(1)–N(9)
Au(1)–P(1)
Au(2)–N(9’)
Au(2)–P(2)
2.052(4) 2.050(7) 2.040(4) 2.042(3) 2.050(9)
2.244(1) 2.242(2) 2.235(1) 2.236(1) 2.225(3)
2.053(7) 2.036(3)
2.243(2) 2.236(1)
N(9)–Au(1)–P(1) 166.3(1) 175.6(2) 177.8(1) 177.78(8) 172.7(3)
N(9’)–Au(2)–P(2) 176.7(2) 177.0(1)
Fig. 6. The polymeric structure of 1 with Au(I)...Au(I) and
π-π-interactions shown as dashed lines.
Fig. 7. The polymeric structure of 3 with Au(I)...Au(I) inter-
actions shown as dashed lines.
usually small N-Au-P angle of 166.3(1)◦, Au...Au
˚
interactions of 3.1641(4) A result in the oligomeri-
sation of the open-chain digold molecules into an
extended polymer (Fig. 6). An edge-to-face π-π-
interaction between C(3B)-H(3B) and the phenyl ring,
˚
A, (C(3B)...centroid C(1-6A) 3.58 A) on an adjacent
molecule, results in the ca. 14◦ digression from 180◦.
This interaction also seems to limit the distance of
the Au...Au separation. Similar polymers have been
reported for Au2(p-thiocresol)2(1,4-bis(diphenylphos-
phine)butane) and Au2(p-thiocresol)2(1,5-bis(diphen-
ylphosphine)pentane) [9].
Fig. 5. The dimeric molecular structure of 11 showing the
numbering scheme. Au(I)...Au(I) interaction is shown as
dashed lines.
Selected bond lengths and angles are summarised in
Table 1.
An analogous polymeric open-chain structure con-
sisting of strands of molecules with aurophilic inter-
˚
All the gold atoms are bonded to phosphorus and actions (3.52 A) parallel to [0, 1, 0] is observed in
amido-nitrogen atoms with bridged phosphines afford- the lattice of 3 (Fig. 7). Additional stabilisation is
ing dinuclear compounds.
achieved by means of π-stacking interactions between
purin-9-ate rings (centroid N(1)-C(6)...centroid N(1)-
Complex 1 exhibits crystallographic inversion sym-
metry (midpoint of the two-carbon chain). Molecules
of 3 possess no crystallographically imposed sym-
metry, however, an approximate two-fold axis passes
through C(11) and lies perpendicular to the plane of
Fig. 2. The gold atoms in 1 and 3 are bound to the
diphosphine ligand on opposite (trans) sides of the
plane defined by the carbon atoms and phosphorus
atoms of the chain, with torsion angles Au-P-P-Au of
180(0) and −129.33(9)◦ respectively.
˚
C(6) 3.59 A) and the phenyl rings, D, (centroid N(1)-
˚
C(6)...centroid C(1-6D) 3.76 A) of an adjacent chain.
All purin-9-ate and purin-6-ylamine-9-ate ligands are
essentially planar.
The 1,3-bis(diphenylphosphine)propane bridge in
7 is not planar as in 3 and the two gold atoms on
each side of the diphosphine ligand are located across
˚
each other with an Au...Au separation of 3.63 A,
the same distance as the sum of the Van der Waals
Each gold atom is two-coordinate and essentially radii for gold [14]. The torsion angle Au-P-P-Au is
linear. Larger deviations from 180◦ for the N-Au-P −51.31(3)◦. Very small departures from linear coor-
angles are detected in compounds which experience dination are evident in the N-Au-P angles of 177.9(1)
aurophilic interactions. In compound 1, with an un- and 177.0(1)◦. The neutral molecules are held to-
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
1611
Table 2. Comparison of bond lengths and angles in
amido(gold)phosphine complexes.
◦
˚ ˚
Au-P [A] Au-N [A] N-Au-P [ ] Ref.
Complex
[Au(1,2,4-triazolate)PPh3 ]2 2.243(2) 2.026(7) 177.1(2)
2.238(2) 2.037(7) 172.7(3)
[11]
Au(imidazolate)PPh3
Au(pyrazolate)PPh3
Au(tetrazolate)PPh3
2.234(2) 2.027(4) 178.4(3)
2.232(2) 2.024(7) 178.0(2)
2.239(2) 2.043(5) 178.4(1)
[4]
[4]
[10]
[12]
Au(purin-6-ylaminate)PPh3 2.240(1) 2.038(4) 177.6(1)
Fig. 8. Two molecules of 7 related by a center of inversion
and six methanol molecules. Hydrogen bonds are shown as
dashed lines.
gether in pairs by two sets of hydrogen bonds involv-
ing the NH2 groups [N(1)...N(10)-H(10A) 2.96 and
˚
H(10B)-N(10)...O(6) 2.95 A] and the imine nitrogen
˚
atoms N(7) and N(7)’, N(7)...N(10)’-H(10B)’ 3.08 A,
˚
N(7)’...N(10)’-H(10A)’ 2.98 A, and are related by
a center of inversion. Complimentary N(3)...O(4)-H
˚
2.84 and N(1)’...O(6)-H 2.83 A hydrogen bonds with
six enclathrated methanol molecules support this ar-
rangement (Fig. 8).
Fig. 9. Molecules of 9 showing interactions between N(1) of
The monophosphine complexes 9 and 11 only differ the purin-9-ate ligand and the Au atom of a neighbour.
as far as the substituents on phosphorus are concerned.
The structure of 9 is analogous to that of triphenylphos-
phine(9H-purin-6-ylamine-9-ate)- gold(I) [12].
P(1AA) 114.7(8), C(2AB)-C(1AB)-P(1AB) 116.1(8)
and C(2AC)-C(1AC)-P(1AC) 113.4(8)◦ in 11, all
larger than 109◦, support the observation of the very
small geminal C-P coupling resulting in broadening of
the signal for the β carbon in their 13C NMR spectra.
No aurophilic interactions are present in the struc-
ture of 9 but interaction between N(1) of the purin-9-
ate ligand and Au atoms in a neighbouring molecule
˚
[N(1)...Au 3.47 and C(4)...C(4) 3.32 A] and an edge-
The crystal structures of 1 and 3 show polymeric
˚
to-face π-π-interaction of 3.64 A between C(8)-H(8) intermolecular aurophilic interactions. An increase
and the phenyl ring, A, [centroid C(1-6A)] govern lat- in the number of carbon atoms (n) [(diphenylphos-
tice organization (Fig. 9). The asymmetric unit con- phine)methane to 1,2-bis(diphenylphosphine)ethane
tains the gold complex and solvent modelled as two to 1,3-bis(diphenylphosphine)propane] in the diphos-
highly disordered methanol molecules. The N-Au- phine backbone results in a change from intramolec-
P angle is normal at 177.78(8)◦. Aurophilic inter- ular to intermolecular aurophilic interactions (dimer
actions are rare in monophosphine gold complexes for n = 2 or polymer formation for n ≥ 2) in the
but have previously been reported for [Au(1,2,4- structure [9]. The strength of aurophilic interactions
˚
triazolate)(PPh3)], Au...Au 3.1971(6) A [11]. A is influenced by the electronic effects of the sub-
slightly larger separation is observed in the structure stituents on gold(I). These weak forces, still in ex-
˚
of 11 (3.2311(7) A) as well as a smaller N-Au-P angle cess of standard Van der Waals (dispersion) interac-
of 172.7(3)◦ (Fig. 5). The unit cell of 11 contains two tions and comparable to hydrogen bonding interac-
molecules in the asymmetric unit. One of them has a tions, can overrule substantial repulsive forces, but
slightly disordered butyl chain.
steric effects and packing forces play a decisive role
Au-P and Au-N bond distances and the N-Au-P in their formation [13, 14]. This is clearly demon-
angle correspond to reported values for amido(gold) strated in the crystal structures of 3 and 7. Both con-
phosphine complexes in Table 2. The C-C-P angles tain the 1,3-bis(diphenylphosphine)propane but one
of 3, 7 and 11, C(11)-C(10)-P(1) 113.4(6), C(11)- forms oligomeric aurophilic intramolecular interac-
C(12)-P(2) 111.9(6) in 3, C(12)-C(11)-P(1) 112.1(3), tions effecting oligomers whereas the other exhibits in-
C(12)-C(13)-P(2) 113.6(3) in 7 and C(2AA)-C(1AA)- tramolecular aurophilic interaction.
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1612
U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
Conclusions
(µ-1,5-bis(diphenylphosphine)pentane)bis(chlorogold),
(triphenylphosphine)gold chloride, (trimethylphosphine)-
Deprotonation of 9H-purine and 9H-purin-6-
ylamine with NaOH and subsequent complexation
to gold(I)phosphine is solvent dependent. The sig-
nals in the 1H NMR and 13C NMR spectra of 9
and 13 were unequivocally assigned with gHSQC
and 1H,13C gHMQC experiments. 1H detected
1H,15N gHMQC experiments yielded the chemical
shifts of the nitrogen atoms in 1 and 13. Magnetic
inequivalence of the bridge carbon atoms and methyl
groups of the 1,2-bis(diphenylphosphine)ethane and
1,2-bis(dimethylphosphine)ethane ligands in 1, 2,
5 and 6 complicates the signals in the 13C NMR
spectra with an AA’XX’ spin system in which
JXXꢀ = 0. No coupling is detected for the carbon
atom β to the phosphorus atom in the bridges of
1,3-bis(diphenylphosphine)propane and 1,5-bis(di-
phenylphosphine)pentane and PBu3 in compounds 3,
4, 7, 8, 11 and 13. Doublets as a result of C-P-coupling
are observed for the other carbon signals. Aurophilic
interactions, hydrogen bonding and π-π-interactions
direct lattice organisation in the crystal structures of 1,
3, 7, 9 and 11. Intermolecular aurophilic interactions
are present in 1 and 3 affording ‘polymers’ in the solid
state but intramolecular aurophilic interactions and
hydrogen bonding prevail in 7. Compounds 2, 6, 10
and 12 are soluble in water and will be screened to
determine their biological activity.
gold chloride, (tributylphosphine)gold chloride) were
prepared by substitution of tht in ClAutht [19, 20] with the
appropriate phosphine. Comparison of the characterisation
data [21 – 24] in the literature confirmed their purity. All the
other starting materials are commercially available and were
used without further purification.
(µ-1,2-Bis(diphenylphosphine)ethane)bis(9H-purin-9-ate)-
gold(I) (1)
A suspension of purine (0.24 g, 2.0 mmol) and (µ-
1,2-bis(diphenylphosphine)ethane)bis(chlorogold) (0.86 g,
1.0 mmol) in methanol (20 ml) was treated with NaOH
(0.08 g, 2.0 mmol) dissolved in methanol (10 ml) and stirred
for 2 h at room temperature. The mixture was filtered and re-
duced to dryness in vacuo. After the addition of H2O (30 ml)
to the residue, filtration, washing with H2O (2×15 ml) and
diethyl ether (3×20 ml), the residue was evaporated to dry-
ness in vacuo to yield colourless, microcrystalline material
(0.76 g, 74%).
M. p. 210 ◦C (dec.). – C36H30Au2N8P2 (1030.57): calcd.
C 41.96, H 2.93, N 10.87; found C 41.69, H 2.88, N 10.75. –
IR (KBr): ν = 3054 (aromatic C-H), 2926 (aliphatic C-
H), 2854 (aliphatic C-H), 1585 (C=N), 1549, 1458, 1389,
1173, 1108, 789, 735 cm−1. – 1H NMR (300 MHz,
CD2Cl2/MeOH-d4): δ = 8.91 (s, 2H, H6), 8.72 (s, 2H, H2),
8.01 (s, 2H, H8), 7.85 (m, 8H, C6H5-meta), 7.59 (m, 4H,
C6H5-para), 7.53 (m, 8H, C6H5-ortho), 3.09 (d, 4H, 2J =
7.2 Hz, P-(CH2)2-P). – 13C NMR (75 MHz, CD2Cl2/MeOH-
d4): δ = 160.1 (s, C4), 155.1 (s, C2), 151.1 (s, C8), 145.7
(s, C6), 134.5 (s, C5), 134.2 (t, 3J = 6.7 Hz, C6H5-meta),
Experimental Section
General
2
133.3 (s, C6H5-para), 130.3 (t, J = 6.1 Hz, C6H5-ortho),
128.7 (d, 1J = 61.5 Hz, C6H5-ipso), 24.1 (m, P-(CH2)2-
P). – 31P NMR (121 MHz, CD2Cl2/MeOH-d4): δ = 29.3. –
1H detected 1H,15N gHMQC (61 MHz, CD2Cl2/MeOH-
d4): δ = −122.0 (s, N1), −130.6 (s, N3), −159.3 (s, N7),
−179.2 (s, N9). ESI-MS (MeOH/CH2Cl2, 50%): m/z =
[M+-C5H3N4] calcd. for C31H27Au2N4P2 911, found 911.
Reactions were carried out under argon using standard
Schlenk and vacuum-line techniques. Tetrahydrofuran
and diethyl ether were distilled under N2 from sodium
diphenylketyl, n-pentane from sodium and CH2Cl2 and
methanol from CaH2. Melting points were determined on
a Stuart Scientific Melting Point Apparatus SMP3 and
are uncorrected. Mass spectra were recorded on a VG
Quattro (ESI, 70 eV) or AMD 604 (EI, 70 eV) instrument,
the infrared spectra on a Perkin-Elmer 1600 Series FTIR
and NMR spectra on a Varian VXR 300 or INOVA 600
spectrometer (δ reported relative to the solvent resonance
(µ-1,2-Bis(dimethylphosphine)ethane)bis(9H-purin-9-ate)-
gold(I) (2)
Compound 2 was prepared in a similar manner to 1
or external reference 85% H3PO4 or CH3NO2). Elemental from purine (0.24 g, 2.0 mmol), (µ-1,2-bis(dimethylphos-
analyses were carried out by Anorganisches Chemisches phine)ethane)bis(chlorogold) (0.64 g, 1.0 mmol) and NaOH
Institut der TU Mu¨nchen in Garching, Department of Chem- (0.08 g, 2.0 mmol) in methanol (45 ml) and the mixture was
istry, University of Cape Town or Microanalytisches Labor stirred for 1.5 h at room temperature. The mixture was fil-
Pascher, Remagen-Bandorf, Germany. Gold(I) starting mate- tered over Na2SO4 and reduced to dryness in vacuo. Af-
rials ((µ-1,2-bis(diphenylphosphine)ethane)bis(chlorogold), ter treatment with diethyl ether (2 × 15 ml) the residue was
(µ-1,2-bis(dimethylphosphine)ethane)bis(chlorogold),
(µ-1,3-bis(diphenylphosphine)propane)bis(chlorogold),
evaporated to dryness in vacuo to yield colourless, micro-
crystalline material (0.84 g), contaminated with NaCl.
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1613
M. p. 179 ◦C (dec.). – C16H22Au2N8P2.1.3NaCl (858.26): 1.0◦mmol) dissolved in H2O (1 ml) and stirred for 2 h at
calcd. C 22.39, H 2.58, N 13.06; found C 22.20, H 2.83, 50 C. The mixture was reduced to dryness in vacuo. After
N 13.32. – IR (KBr): ν = 2978 (aliphatic C-H), 2901 the addition of THF (15 ml) the solution was layered with
(aliphatic C-H), 1591 (C=N), 1556, 1464, 1393, 1291, 1193, n-pentane. The resulting precipitate was dissolved in ace-
1
1100, 911, 800, 648 cm−1. – H NMR (300 MHz, MeOH- tone (15 ml) and filtered over Na2SO4. The clear solution
d4): δ = 8.79 (s, 2H, H6), 8.64 (s, 2H, H2), 7.92 (s, 2H, was layered with diethyl ether and the resulting precipitate
2
H8), 2.49 (d, 4H, J = 8.9 Hz, P-(CH2)2-P), 1.87 (d, 12H, was filtered off, washed with diethyl ether (15 ml) and dried
2J = 11.1 Hz, CH3). – 13C NMR (75 MHz, MeOH-d4): in vacuo to give a beige, microcrystalline material (0.13 g,
δ = 161.1 (s, C4), 156.7 (s, C2), 151.3 (s, C8), 145.8 (s, 24%).
◦
C6), 135.4 (s, C5), 24.8 (m, P-(CH2)2-P), 13.4 (m, CH3). –
M. p. 96 C (dec.). – C39H36Au2N8P2 (1072.66): calcd.
1
31P NMR (121 MHz, MeOH-d4): δ = −0.2. – H detected
C 43.67, H 3.38, N 10.45; found C 43.29, H 2.99, N 10.46. –
IR (KBr): ν = 3051 (aromatic C-H), 2924 (aliphatic C-H),
2856 (aliphatic C-H), 1590 (C=N), 1557, 1464, 1436, 1393,
1192, 1104, 908, 743, 692 cm−1. – 1H NMR (300 MHz,
MeOH-d4): δ = 8.90 (s, 2H, H6), 8.66 (s, 2H, H2), 8.39
(s, 2H, H8), 7.68 (m, 8H, C6H5-meta), 7.44 (m, 12H,
C6H5-para, -ortho), 2.66 (m, 4H, P-CH2(CH2)3CH2-P),
1.82 (m, 6H, P-CH2(CH2)3CH2-P). – 13C NMR (75 MHz,
MeOH-d4): δ = 160.8 (s, C4), 156.6 (s, C2), 151.9 (s,
1H,15N gHMQC (61 MHz, MeOH-d4): δ = −123.4 (s, N1),
−131.6 (s, N3). – ESI-MS (MeOH): m/z = [MH+-C5H3N4]
calcd. for C11H20Au2N4P2 664, found 664.
(µ-1,3-Bis(diphenylphosphine)propane)bis(9H-purin-9-
ate)gold(I) (3)
Complex
3 was prepared as above from purine
(0.24 g, 2.0 mmol), (µ-1,3-bis(diphenylphosphine)propane)
bis(chlorogold) (0.88 g, 1.0 mmol) and NaOH (0.08 g,
2.0 mmol) in methanol (35 ml). The mixture was stirred for
1 h at room temperature, filtered over celite and reduced
to dryness in vacuo. The crude product was treated with
H2O (25 ml), filtered and washed with H2O (3 × 15 ml)
and diethyl ether (3 × 15 ml). The product was evaporated
to dryness, to yield slightly pinkish, microcrystalline mate-
rial (0.59 g, 57%).
3
C8), 146.4 (s, C6), 135.2 (s, C5), 134.5 (d, J = 12.8 Hz,
C6H5-meta), 133.5 (d, 4J = 2.4 Hz, C6H5-para), 130.7
(d, 2J = 11.6 Hz, C6H5-ortho), 130.6 (d, 1J = 60.9 Hz,
C6H5-ipso), 31.0 (t, 3J = 15.2 Hz, P-(CH2)2CH2(CH2)2-
P), 26.4 (d, 1J = 39.0 Hz, P-CH2(CH2)3CH2-P), 25.0 (s, P-
CH2CH2CH2CH2CH2-P). – 31P NMR (121 MHz, MeOH-
d4): δ = 29.3. – ESI-MS (MeOH): m/z = [MH+-C5H3N4]
calcd. for C34H34Au2N4P2 954, found 954.
M. p. 90 – 97 ◦C. – C37H32Au2N8P2 (1044.60): calcd.
C 42.54, H 3.09, N 10.73; found C 42.23, H 3.01, N 10.95. –
IR (KBr): ν = 3050 (aromatic C-H), 2919 (aliphatic C-
H), 2855 (aliphatic C-H), 1590 (C=N), 1551, 1464, 1436,
1393, 1193, 1104, 744, 692 cm−1. – 1H NMR (300 MHz,
CD2Cl2): δ = 8.99 (s, 2H, H6), 8.64 (s, 2H, H2), 8.01 (s, 2H,
H8), 7.69 (m, 8H, C6H5-meta), 7.48 (m, 4H, C6H5-para),
7.38 (m, 8H, C6H5-ortho), 3.11 (m, 4H, P-CH2CH2CH2-
P), 2.06 (m, 2H, P-CH2CH2CH2-P). – 13C NMR (75 MHz,
CD2Cl2): δ = 160.4 (s, C4), 154.5 (s, C2), 151.6 (s, C8),
146.5 (s, C6), 135.0 (s, C5), 133.8 (d, 3J = 12.8 Hz,
C6H5-meta), 132.9 (d, 4J = 2.4 Hz, C6H5-para), 130.9
(d, 2J = 11.6 Hz, C6H5-ortho), 128.7 (d, 1J = 60.9 Hz,
C6H5-ipso), 27.5 (dd, 1J = 38.6 Hz, 3J = 9.8 Hz, P-
CH2CH2CH2-P), 19.7 (bs, P-CH2CH2CH2-P). – 31P NMR
(µ-1,2-Bis(diphenylphosphine)ethane)bis(9H-purin-6-yl-
amine-9-ate)gold(I) (5)
Compound 5 was prepared in the same manner as 4
from NaOH (65 mg, 1.6 mmol), purin-6-ylamine (0.22 g,
1.6 mmol) and (µ-1,2-bis(diphenylphosphine)ethane)
bis(chlorogold) (0.70 g, 0.8 mmol) in DME (30 ml). The
mixture was stirred for 2 h at 45 ◦C and reduced to dryness in
vacuo. After the addition of methanol (30 ml) to the residue,
◦
the mixture was stirred at 50 C, followed by hot filtration
over Na2SO4 and solvent removal. The crude product was
washed with H2O (2 × 15 ml) and diethyl ether (2 × 20 ml)
and dried in vacuo, to yield colourless, microcrystalline
material (0.45 g, 53%).
M. p. 179 ◦C (dec.). – C36H32Au2N10P2 (1060.60): calcd.
C 40.77, H 3.04, N 13.21; found C 40.57, H 3.00, N 12.97. –
IR (KBr): ν = 3319, 3166 (N-H), 1633 (N-H), 1595 (C=N),
1553, 1462, 1436, 1393, 1193, 1104, 692 cm−1. – 1H NMR
(300 MHz, MeOH-d4): δ = 8.07 (s, 2H, H2), 7.86 (m, 8H,
C6H5-meta), 7.71 (s, 2H, H8), 7.52 (m, 12H, C6H5-para,
-ortho), 3.09 (d, 4H, 2J = 9.4 Hz, P-(CH2)2-P). – 13C NMR
(121 MHz, CD2Cl2): δ = 23.3. – 1H detected 1H,15
N
gHMQC (61 MHz, CD2Cl2): δ = −109.4 (s, N1), −123.0
(s, N3). – ESI-MS (MeOH/CH2Cl2, 50%): m/z = [MH+-
C5H3N4] calcd. for C32H30Au2N4P2 926, found 926.
(µ-1,5-Bis(diphenylphosphine)pentane)bis(9H-purin-9-
ate)gold(I) (4)
(75 MHz, MeOH-d4): δ = 157.9 (s, C4), 156.8 (s, C6),
3
A suspension of purine (0.12 g, 1.0 mmol) and (µ- 152.0 (s, C2), 150.0 (s, C8), 135.0 (t, J = 6.7 Hz, C6H5-
1,5-bis(diphenylphosphine)pentane)bis(chlorogold) (0.45 g, meta), 133.9 (s, C6H5-para), 130.9 (t, J = 5.5 Hz, C6H5-
0.5 mmol) in DME (20 ml) was treated with NaOH (40 mg, ortho), 130.1 (d, J = 60.9 Hz, C6H5-ipso), 120.6 (s, C5),
2
1
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1614
U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
23.5 (m, P-(CH2)2-P). – 31P NMR (121 MHz, MeOH-d4): (s, C6), 151.7 (s, C2), 150.8 (s, C8), 134.8 (d, 3J = 12.8 Hz,
4
δ = 28.2. – ESI-MS (MeOH): m/z = [M+-C5H4N5] calcd. C6H5-meta), 133.5 (d, J = 1.3 Hz, C6H5-para), 130.7 (d,
for C31H28Au2N4P2 926, found 926.
2J = 11.6 Hz, C6H5-ortho), 129.8 (s, C6H5-ipso), 120.8 (s,
C5), 27.6 (dd, 1J = 38.0 Hz, 3J = 9.1 Hz, P-CH2CH2CH2-
P), 20.7 (bs, P-CH2CH2CH2-P). – 31P NMR (121 MHz,
MeOH-d4): δ = 25.0. – ESI-MS (MeOH): m/z = [M+-
C5H4N5-H] calcd. for C32H29Au2N5P2 940, found 940.
(µ-1,2-Bis(dimethylphosphine)ethane)bis(9H-purin-6-yl-
amine-9-ate)gold(I) (6)
Complex 6 was obtained in a similar fashion to 4
from NaOH (65 mg, 1.6 mmol), purin-6-ylamine (0.22 g,
1.6 mmol) and (µ-1,2-bis(dimethylphosphine)ethane)
bis(chlorogold) (0.50 g, 0.81 mmol) in DME (20 ml). The
mixture was stirred for 1.5 h at 45 ◦C and reduced to dryn◦ess
(µ-1,5-Bis(diphenylphosphine)pentane)bis(9H-purin-6-yl-
amine-9-ate)gold(I) (8)
The same method as described above was used to
in vacuo. After treatment with methanol (30 ml) at 45 C, prepare 8 from NaOH (64 mg, 1.6 mmol), purin-6-
hot filtration over Na2SO4 and solvent removal the residue ylamine (0.22 g, 1.6 mmol) and (µ-1,5-bis(diphenylphos-
was treated with n-pentane (15 ml) and dried in vacuo, to phine)pentane)bis(chlorogold) (0.72 g, 0.8 mmol) in DME
yield colourless, microcrystalline material (0.61 g, 92%), (30 ml). The mixture was stirred for 1 h at 50 ◦C, filtered and
contaminated with NaCl.
the remaining precipitate was washed with DME (10 ml),
CH2Cl2 (2 × 30 ml), H2O (2 × 40 ml) and MeOH (30 ml)
to remove unreacted material as well as side products. After
the addition of diethyl ether (3×30 ml) to the residue, the fil-
trate was dried in vacuo to give a colourless, microcrystalline
product (0.37 g, 42%).
M. p. 165 ◦C (dec.). – C16H24Au2N10P2.1.8NaCl.1.1C
H3OH (952.76): calcd. C 21.56, H 3.00, N 14.70; found
C 21.40, H 3.08, N 14.91. – IR (KBr): ν = 3280 (N-
H), 2955 (aliphatic C-H), 2880 (aliphatic C-H), 1632 (N-
H), 1553, 1460, 1388, 1191, 1135, 952, 801, 654 cm−1. –
1H NMR (300 MHz, MeOH-d4): δ = 8.08 (s, 2H, H2),
M. p. 170 – 175 ◦C. – C39H38Au2N10P2 (1102.68): calcd.
7.69 (s, 2H, H8), 2.41 (d, 4H, 2J = 9.1 Hz, P-(CH2)2-P), C 42.48, H 3.47, N 12.70; found C 42.18, H 3.63,
1.90 (d, 12H, 2J = 11.1 Hz, CH3). – 13C NMR (75 MHz, N 12.31. – IR (KBr): ν = 3456, 3307, 3152 (N-H),
MeOH-d4): δ = 157.4 (s, C4), 156.8 (s, C6), 152.0 (s, C2), 1640 (C=O), 1590 (N-H), 1551 (C=N), 1463, 1436, 1391,
149.5 (s, C8), 120.4 (s, C5), 24.4 (m, P-(CH2)2-P), 13.4 (m, 1198, 1107, 977, 748, 693 cm−1. – 1H NMR (300 MHz,
CH3). – 31P NMR (121 MHz, MeOH-d4): δ = 0.2. – ESI-MS CD2Cl2/MeOH-d4): δ = 8.07 (s, 2H, H2), 7.84 (s, 2H,
(MeOH): m/z = [MH+-C5H4N5] calcd. for C11H21Au2N5P2 H8), 7.69 (m, 8H, C6H5-meta), 7.47 (m, 12H, C6H5-para,
679, found 679.
-ortho), 2.54 (m, 4H, P-CH2(CH2)3CH2-P), 1.73 (m, 6H, P-
CH2(CH2)3CH2-P). – 13C NMR (75 MHz, CD2Cl2/MeOH-
d4): δ = 160.0 (s, C4), 156.1 (s, C6), 151.6 (s, C2), 149.3
(bs, C8), 134.0 (d, 3J = 12.2 Hz, C6H5-meta), 132.8 (s,
C6H5-para), 130.1 (d, 2J = 11.0 Hz, C6H5-ortho), 129.8
(d, 1J = 60.3 Hz, C6H5-ipso), 119.9 (s, C5), 31.5 (t,
3J = 14.6 Hz P-CH2CH2CH2CH2CH2-P), 27.1 (d, 1J =
37.8 Hz, P-CH2(CH2)3CH2-P), 25.1 (P-(CH2)2CH2(CH2)2-
P). – 31P NMR (121 MHz, CD2Cl2/MeOH-d4): δ = 28.4. –
ESI-MS (MeOH/CH2Cl2, 50%): m/z = [M+-C5H4N5-H]
calcd. for C34H33Au2N5P2 968, found 968.
(µ-1,3-Bis(diphenylphosphine)propane)bis(9H-purin-6-yl-
amine-9-ate)gold(I) (7)
Compound 7 was prepared by the same method as
complex 4 from NaOH (0.07 g, 1.8 mmol), purin-6-
ylamine (0.23 g, 0.85 mmol) and (µ-1,3-bis(diphenylphos-
phine)propane)bis(chlorogold) (0.◦75 g, 0.85 mmol) in DME
(30 ml) and stirred for 1 h at 45 C, followed by filtration.
The filtrate was reduced to dryness in vacuo. After addition
of methanol (30 ml) to the residue, the mixture was stirred for
15 min at 45 ◦C, followed by hot filtration over Na2SO4 and
solvent removal. The crude product was washed with H2O
(2 × 15 ml) and diethyl ether (2 × 20 ml) and evaporated to
Triphenylphosphine(9H-purin-9-ate)gold(I) (9)
Complex 9 was prepared in the same fashion as de-
dryness in vacuo, to yield colourless, microcrystalline mate- tailed above from NaOH (0.04 g, 1.0 mmol), purine (0.12 g,
rial (0.48 g, 53%).
1.0 mmol) and (triphenylphosphine)gold chloride (0.50 g,
1.0 mmol) in DME (20 ml). The mixture was stirred for 1 h
M. p. 224 ◦C (dec.). – C37H34Au2N10P2.0.1CH3OH
(1077.83): calcd. C 41.34, H 3.22, N 13.00; found C 41.55,
H 2.98, N 13.24. – IR (KBr): ν = 3325, 3190 (N-H),
1633 (N-H), 1595 (C=N), 1554, 1462, 1436, 1393, 1196,
1104, 692 cm−1. – 1H NMR (300 MHz, MeOH-d4): δ =
7.99 (s, 2H, H2), 7.74 (m, 10H, H8, C6H5-meta), 7.49
(m, 4H, C6H5-para), 7.42 (m, 8H, C6H5-ortho), 3.18 (m,
4H, P-CH2CH2CH2-P), 2.06 (m, 2H, P-CH2CH2CH2-P). –
◦
at 45 C and reduced to dryness in vacuo. After treatment
◦
with H2O (20 ml) for 10 min at 45 C and hot filtration,
the filtrate was washed with H2O (2 × 10 ml) and diethyl
ether (2×15 ml) and dried in vacuo. The residue was treated
with methanol (20 ml), filtered and, after solvent removal,
the colourless product (0.43 g, 80%) was dried in vacuo.
M. p. 235 – 237 ◦C. – C23H18AuN4P.1.0CH3OH (610.41):
13C NMR (75 MHz, MeOH-d4): δ = 158.8 (s, C4), 156.7 calcd. C 47.23, H 3.63, N 9.18; found C 46.85, H 3.25,
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
1615
N 9.31. – IR (KBr): ν = 3376, 3282 (N-H), 3072 (aro-
M. p. 79 – 80 ◦C. – C17H30AuN4P (518.40): calcd.
matic C-H), 1590 (C=N), 1551, 1464, 1434, 1393, 1181, C 39.39, H 5.83, N 10.81; found C 39.42, H 5.56, N 10.67. –
1098, 747 cm−1. – 1H NMR (600 MHz, CD2Cl2): δ = 9.02 IR (KBr): ν = 3076, 3034 (N-H), 2956 (aliphatic C-H), 2926
(s, 1H, H6), 8.82 (s, 1H, H2), 8.14 (s, 1H, H8), 7.65 (m, (aliphatic C-H), 2869 (aliphatic C-H), 1584 (C=N), 1552,
6H, C6H5-meta), 7.60 (m, 3H, C6H5-para), 7.55 (m, 6H, 1464, 1387, 1194, 1177, 1096, 902, 787, 652, 482 cm−1. –
C6H5-ortho). – 13C NMR (151 MHz, CD2Cl2): δ = 160.4 1H NMR (300 MHz, CD2Cl2): δ = 9.00 (s, 1H, H6),
(s, C4), 154.1 (s, C2), 151.5 (s, C8), 146.0 (s, C6), 134.6 8.80 (s, 1H, H2), 8.06 (s, 2H, H8), 1.91 (m, 6H, P-
4
(d, 3J = 13.4 Hz, C6H5-meta, C5), 132.6 (d, J = 2.4 Hz, CH2CH2CH2CH3), 1.64 (m, 6H, P-CH2CH2CH2CH3), 1.52
C6H5-para), 129.8 (d, 2J = 12.2 Hz, C6H5-ortho), 128.8 (d, (m, 6H, P-CH2CH2CH2CH3), 0.95 (t, 9H, 3J = 7.17 Hz,
1J = 62.9 Hz, C6H5-ipso). – 31P NMR (121 MHz, CD2Cl2): P-CH2CH2CH2CH3). – 13C NMR (75 MHz, CD2Cl2):
δ = 32.4. – ESI-MS (CH2Cl2): m/z = [M+-H] calcd. for δ = 160.7 (s, C4), 154.4 (s, C2), 151.7 (s, C8), 146.0 (s,
C23H17AuN4P 538, found 538; [((C6H5)3P)2Au-H] calcd. C6), 134.9 (s, C5), 27.6 (s, P-CH2CH2CH2CH3), 25.2 (d,
for C36H29AuP2 721, found 721; [M++AuP(C6H5)3-H] 1J = 37.2 Hz, P-CH2CH2CH2CH3), 24.3 (d, 3J = 14.6 Hz,
calcd. for C41H32Au2N4P2 1037, found 1037.
P-CH2CH2CH2CH3), 13.6 (s, P-CH2CH2CH2CH3). –
31P NMR (121 MHz, CD2Cl2): δ = 20.0. – ESI-MS
(MeOH): m/z = [MH+] calcd. for C17H31AuN4P 519, found
519, [((C4H9)3P)2Au-H] calcd. for C24H53AuP2 601, found
601; [M++AuP(C4H9)3-H] calcd. for C29H56Au2N4P2 917,
found 917.
Trimethylphosphine(9H-purin-9-ate)gold(I) (10)
Compound 10 was prepared in the same manner as 1
from NaOH (0.04 g, 1.0 mmol), purine (0.12 g, 1.0 mmol)
and (trimethylphosphine)gold chloride (0.31 g, 1.0 mmol) in
methanol (20 ml). The mixture was stirred for 1 h at room
temperature and reduced to dryness in vacuo. After treat-
ment with CH2Cl2 (30 ml), filtration over Na2SO4 and sol-
vent removal the colourless product (0.33 g, 84%) was dried
in vacuo.
M. p. 155 – 160 ◦C. – C8H12AuN4P (392.15): calcd.
C 24.50, H 3.08, N 14.29; found C 24.65, H 3.20, N 13.92. –
IR (KBr): ν = 2986 (aliphatic C-H), 2955 (aliphatic C-
H), 2875 (aliphatic C-H), 1589 (C=N), 1551, 1461, 1391,
1172, 1103, 969, 650 cm−1. – 1H NMR (600 MHz, MeOH-
d4): δ = 8.98 (s, 1H, H6), 8.76 (s, 1H, H2), 8.26 (s,
1H, H8), 1.69 (d, 9H, 2J = 11.2 Hz, CH3). – 13C NMR
(151 MHz, MeOH-d4): δ = 160.8 (s, C4), 156.1 (s, C2),
151.4 (s, C8), 146.0 (m, C6), 135.2 (s, C5), 15.2 (d, 1J =
42.1 Hz, CH3). – 31P NMR (243 MHz, MeOH-d4): δ =
−9.0. – 1H detected 1H,15N gHMQC (61 MHz, MeOH-
d4): δ = −122.4 (s, N1), −132.6 (s, N3). – MS (EI,
70 eV): m/z (%) = 392 (3) [M+], 273 (6) [M-C5H5N4], 120
(100) [C5H5N4], 76 (42) [P(CH3)3], 61 (58) [P(CH3)2]. –
ESI-MS (MeOH/CH2Cl2, 50%): m/z = [((CH3)3P)2Au]
calcd. for C6H18AuP2 349, found 349; [M+] calcd. for
C8H12AuN4P 392, found 392; [M++AuP(CH3)3] calcd. for
C11H22Au2N4P2 666, found 666.
Trimethylphosphine(9H-purin-6-ylamine-9-ate)gold(I) (12)
Compound 12 was prepared in the same manner as 4
from NaOH (42 mg, 1.1 mmol), purin-6-ylamine (0.10 g,
1.0 mmol) and (trimethylposphine)gold chloride (0.32 g,
1.0 mmol) in THF (20 ml). The mixture was stirred for 2 h at
50 ◦C and reduced to dryness in vacuo. After the addition of
methanol (20 ml) to the residue and filtration over Na2SO4,
the solvent was reduced to dryness in vacuo. The product was
treated with CH2Cl2 (60 ml) for 30 min at 30 ◦C followed by
filtration over Na2SO4. Solvent was removed and the residue
was dried in vacuo to give a colourless product (0.42 g, 99%).
M. p. 163 ◦C (dec.). – C8H13AuN5P (407.17): calcd.
C 23.60, H 3.22, N 17.20; found C 23.82, H 3.19, N 17.52. –
IR (KBr): ν = 3258, 3092 (N-H), 2898 (aliphatic C-H),
2704, 1674 (C=O), 1698 (N-H), 1543 (C=N), 1459, 1391,
1319, 1195, 1032, 962, 801, 747, 680 cm−1. – 1H NMR
(300 MHz, MeOH-d4): δ = 8.11 (s, 1H, H2), 7.85 (s, 1H,
H8), 1.69 (d, 9H, 2J = 11.8 Hz, CH3). – 13C NMR (75 MHz,
MeOH-d4): δ = 158.3 (s, C4), 157.1 (s, C6), 152.0 (s,
C2), 150.3 (s, C8), 120.6 (s, C5), 14.9 (d, 1J = 41.4 Hz,
CH3). – 31P NMR (121 MHz, MeOH-d4): δ = −8.7. –
ESI-MS (MeOH/CH2Cl2, 50%): m/z = [((CH3)3P)2Au]
calcd. for C6H18AuP2 349, found 349; [MH+] calcd. for
C8H14AuN5P 408, found 408; [M++(CH3)3PAu] calcd. for
C11H22Au2N5P2 680, found 680.
Tributylphosphine(9H-purin-9-ate)gold(I) (11)
Complex 11 was prepared in a similar fashion to 1
from NaOH (0.06 g, 1.5 mmol), purine (0.18 g, 1.5 mmol)
and (tributylphosphine)gold chloride (0.64 g, 1.5 mmol) in
Tributylphosphine(9H-purin-6-ylamine-9-ate)gold(I) (13)
The same method as described above was used to prepare
methanol (11 ml). The mixture was stirred for 2 h at room 13 from NaOH (29 mg, 0.7 mmol), purin-6-ylamine (0.10 g,
temperature and reduced to dryness in vacuo. After the addi- 0.7 mmol) and (tributylphosphine)gold chloride (0.32 g,
tion of CH2Cl2 (30 ml) to the residue, filtration over Na2SO4 0.7 mmol) in DME (20 ml). The mixture was stirred for 1 h at
and solvent removal, the colourless product (0.16 g, 21%) 45 ◦C and reduced to dryness in vacuo. After the addition of
was dried in vacuo.
H2O (50 ml) to the residue, filtration, and washing with H2O
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1616
U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
(20 ml) and diethyl ether (3 ×11 ml), the colourless product colourless cube, 0.20×0.15×0.10 mm3, monoclinic, space
(0.25 g, 60%) was dried in vacuo.
group P21/n (No. 14), a = 11◦.473(6), b = 18.097(9), c =
M. p. 102 ◦C (dec.). – C17H31AuN5P (533.41): calcd.
C 38.28, H 5.86, N 13.13; found C 37.97, H 5.56, N 13.23. –
IR (KBr): ν = 3305, 3126 (N-H), 2953, 2926, 2868, 2706
(aliphatic C-H), 1670 (C=O), 1596 (N-H), 1548 (C=N),
1461, 1393, 1316, 1194, 1039, 905, 802, 724, 656 cm−1. –
1H NMR (300 MHz, CD2Cl2): δ = 8.19 (s, 1H, H2),
7.73 (s, 1H, H8), 5.70 (s, 2H, NH2), 1.86 (m, 6H, P-
CH2CH2CH2CH3), 1.61 (m, 6H, P-CH2CH2CH2CH3), 1.51
3
˚
˚
17.462(9) A, β = 103.979(9) , V = 3518(3) A , Z = 4,
Dc = 1.972 g/cm3, F000 = 1992, T = 273(2) K, 2θmax
=
=
56.7◦, 21292 reflections collected, 8066 unique (Rint
0.0578). Final GooF = 0.951, R1 = 0.0564, wR2 = 0.1373,
R indices based on 6584 reflections with I > 2σ(I) (refine-
ment on F2), 443 parameters, 0 restraints, µ = 8.461 mm−1
.
Crystal data for 7: C43H58Au2N10O6P2, M = 1266.87,
colourless cube, 0.3 × 0.2 × 0.1 mm3, triclinic, space group
3
¯
(m, 6H, P-CH2CH2CH2CH3), 0.94 (t, 9H, J = 7.1 Hz, P-
P1 (No. 2), a = 13.7375(14), b = 13.8501(14), c =
CH2CH2CH2CH3). – 13C NMR (75 MHz, CD2Cl2): δ =
158.9 (s, C4), 155.7 (s, C6), 151.6 (s, C2), 149.1 (s,
C8), 120.7 (s, C5), 27.5 (s, P-CH2CH2CH2CH3), 25.2 (d,
1J = 36.7 Hz, P-CH2CH2CH2CH3), 24.3 (d, 3J = 10.7 Hz,
˚
14.1405(15) A, α = 105.856(2), β = 103.057(2), γ =
◦
3
3
˚
97.354(2) , V = 2469.0(4) A , Z = 2, Dc = 1.704 g/cm ,
F000 = 1244, T = 273(2) K, 2θmax = 56.6◦, 28316 reflec-
tions collected, 11294 unique (Rint = 0.0224). Final GooF =
1.045, R1 = 0.0328, wR2 = 0.0822, R indices based on
10297 reflections with I > 2σ(I) (refinement on F2), 597
P-CH2CH2CH2CH3), 13.6 (s, P-CH2CH2CH2CH3).
–
31P NMR (121 MHz, CD2Cl2): δ = 20.1. – 1H detected
1H,15N gHMQC (61 MHz, CD2Cl2/MeOH-d4): δ = −144.5
(s, N3), −147.0 (s, N7), −150.3 (s, N1), −174.2 (s,
N9), −311.9 (s, N10). – ESI-MS (MeOH/CH2Cl2, 50%):
m/z = [M+] calcd. for C17H31AuN5P 533, found 533;
[((C4H9)3P)2Au] calcd. for C24H54AuP2 602, found 602.
parameters, 0 restraints, µ = 6.055 mm−1
.
Crystal data for 9: C25H26AuN4O2P, M = 642.43,
colourless cube, 0.2 × 0.18 × 0.1 mm3, triclinic, space
¯
group P1 (No. 2), a = 9.0338(9), b = 11.8382(11), c =
˚
13.0714(13) A, α = 97.746(2), β = 107.9950(10), γ =
◦
3
3
˚
111.1330(10) ,V = 1191.4(2) A , Z = 2, Dc = 1.791 g/cm ,
F000 = 628, T = 100(2) K, 2θmax = 56.5◦, 13688 reflections
collected, 5470 unique (Rint = 0.0226). Final GooF = 0.739,
R1 = 0.0271, wR2 = 0.0817, R indices based on 5208 reflec-
tions with I > 2σ(I) (refinement on F2), 305 parameters, 2
X-ray crystal structure determinations
Single crystals of 1 and 9 suitable for X-ray analysis,
were obtained◦by slow crystallisation from methanol/diethyl
ether at −30 C; those of 3 and 11 from dichloromethane
and 7 from methanol. A Bruker SMART Apex diffractome-
ter [25 – 27] with graphite monochromated Mo-Kα radiation
restraints, µ = 6.271 mm−1
.
Crystal data for 11: C17H30AuN4P, M = 518.39, colour-
less cube, 0.20 × 0.20 × 0.15 mm3, triclinic, space group
˚
(λ = 0.71073 A) was used to collect intensity data. Intensi-
¯
P1 (No. 2), a = 15.3118(18), b = 15.5609(18), c =
ties were measured using the ω-scan mode and corrected for
Lorentz and polarisation effects. All structures were solved
by direct methods and refined by full matrix least squares
on F2 using the SHELXL-97 program package [28] and
X-seed [29, 30]. All non-hydrogen atoms were refined with
anisotropic displacement parameters. All hydrogen atoms
were placed in calculated positions. Figures were generated
with X-seed [30], (displacement ellipsoids are at the 50%
probability level). Hydrogen atoms and solvent molecules
were omitted for clarity.
˚
18.467(2)◦ A, α = 106.099(2), β = 105.031(2), γ =
3
3
˚
98.973(2) , V = 3957.9(8) A , Z = 8, Dc = 1.740 g/cm ,
F000 = 2032, T = 100(2) K, 2θmax = 56.8◦, 45658 reflec-
tions collected, 18205 unique (Rint = 0.0644). Final GooF =
1.019, R1 = 0.0674, wR2 = 0.1498, R indices based on
11786 reflections with I > 2σ(I) (refinement on F2), 826
parameters, 17 restraints, µ = 7.520 mm−1
.
Crystallographic data for the structures have been de-
posited with the Cambridge Crystallographic Data Cen-
tre, CCDC 250917 - 250921. Copies of the data can
be obtained free of charge on application to The Di-
rector, CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK (Fax: int.code+(1223)336-033; e-mail for inquiry:
fileserv@ccdc.cam.ac.uk).
Crystal data for 1: C36H30Au2N8P2, M = 1030.55,
colourless cube, 0.10×0.12×0.08 mm3, monoclinic, space
groupC2/c (No. 15), a = 15.4448(10), b = 19.9492(13), c =
◦
3
˚
˚
11.1836(7) A, β = 106.9670(10) , V = 3295.8(4) A , Z =
4, Dc = 2.077 g/cm3, F000 = 1960, T = 273(2) K, 2θmax
=
=
56.5◦, 10294 reflections collected, 3801 unique (Rint
Acknowledgements
0.0352). Final GooF = 0.991, R1 = 0.0327, wR2 = 0.0695,
R indices based on 3236 reflections with I > 2σ(I) (refine-
We thank the Claude Harris Leon Foundation and Har-
mony Gold Mining Co. Ltd. for financial support of this work
and Mintek for the generous loan of gold.
ment on F2), 217 parameters, 0 restraints, µ = 9.031 mm−1
.
Crystal data for 3: C37H32Au2N8P2, M = 1044.58,
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U. E. I. Horvath et al. · Mono- and Binuclear Gold(I) Amido Compounds of Purine Derivatives
1617
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