Gold complexes with potentially tri- and tetradentate phosphinothiolate ligands

Article abstract of DOI:10.1021/ic000015y

Reactions of [Au(PPh₃)Cl], (Bu₄N)[AuCl₄] and the organometallic gold complex [Au(damp-C¹,N)Cl₂] (damp^- = 2-(N,N-dimethylaminomethyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C₆H₃-SH-2-R-3)₂ (H₂L(1a), R = SiMe₃; H₂L(1b), R = H) and P(C₆H₄-SH-2)₃ (H₃L²) result in the formation of mono- or dinuclear gold complexes depending on the precursor used. Monomeric complexes of the type [AuL¹Cl] are formed upon the reaction with [Au(damp-C¹,N)Cl₂], but small amounts of dinuclear [AuL¹]₂ complexes with gold in two different oxidation states, +1 and +3, have been isolated as side-products. The dinuclear compounds are obtained in better yields from [AuCl₄]^-. A dinuclear complex having two Au(III) centers can be isolated from the reaction of [Au-(PPh₃)Cl] with H₃L², whereas from the reaction with H₂L(1b) the mononuclear [Au(Ph₃P)HL(1b)] is obtained, which contains a three-coordinate gold atom. Comparatively short gold-gold distances have been found in the dinuclear complexes (2.978(2) and 3.434(1) A). They are indicative of weak gold-gold interactions, which is unusual for gold(III).

Full text of DOI:10.1021/ic000015y

Inorg. Chem. 2000, 39, 2801-2806
2801
Gold Complexes with Potentially Tri- and Tetradentate Phosphinothiolate Ligands
Kirstin Ortner,†,‡ Louise Hilditch,§ Yifan Zheng,§ Jonathan R. Dilworth,§ and Ulrich Abram*,|
Institute of Inorganic Chemistry, University of Tu¨bingen, Auf der Morgenstelle 18,
D-72076 Tu¨bingen, Germany, Inorganic Chemistry Laboratories, University of Oxford, South Parks
Road, Oxford, OX1 3QR, U.K., and Institute of Chemistry/Inorganic and Analytical Chemistry, Freie
Universita¨t Berlin, Fabeckstrasse 34-36, D-14195 Berlin, Germany
ReceiVed January 5, 2000
Reactions of [Au(PPh3)Cl], (Bu4N)[AuCl4] and the organometallic gold complex [Au(damp-C1,N)Cl2] (damp- )
2-(N,N-dimethylaminomethyl)phenyl) with the potentially tri- and tetradentate proligands PhP(C6H3-SH-2-
R-3)2 (H2L1a, R ) SiMe3; H2L1b, R ) H) and P(C6H4-SH-2)3 (H3L2) result in the formation of mono- or dinuclear
gold complexes depending on the precursor used. Monomeric complexes of the type [AuL1Cl] are formed upon
the reaction with [Au(damp-C1,N)Cl2], but small amounts of dinuclear [AuL1]2 complexes with gold in two different
oxidation states, +1 and +3, have been isolated as side-products. The dinuclear compounds are obtained in better
yields from [AuCl4]-. A dinuclear complex having two Au(III) centers can be isolated from the reaction of [Au-
(PPh3)Cl] with H3L2, whereas from the reaction with H2L1b the mononuclear [Au(Ph3P)HL1b] is obtained, which
contains a three-coordinate gold atom. Comparatively short gold-gold distances have been found in the dinuclear
complexes (2.978(2) and 3.434(1) Å). They are indicative of weak gold-gold interactions, which is unusual for
gold(III).
Introduction
For the last metal, however, bridging coordination of metal
centers with the ligand H2L1 or H3L2 has also been observed.
The coordination chemistry of potentially tri- and tetradentate
proligands of the types PhP(C6H3-SH-2-R-3)2 (H2L1a, R )
SiMe3; H2L1b, H) and P(C6H4-SH-2)3 (H3L2) has been
These complexes show unusual coordination polyhedra and
redox behavior.2,10 Thus, [Ni2{PhP(C6H4-S)3}2]2+ can be
oxidized to yield the mixed-valence [Ni(II)/Ni(III)] complex
[Ni2{PhP(C6H4-S-2)3}2]+. The oxidation is associated with
considerable changes in the molecular structure and a shortening
of the metal-metal distances, which is indicative of Ni-Ni
interactions in the mixed-valence species.10
The unusual abilities of phosphinothiolate ligands to stabilize
complexes with metals in high formal oxidation states prompted
us to investigate their chemistry with gold. The synthesis and
structure of a mononuclear gold(III) cation with the bidentate
{Ph2P(C6H4-S-2)}- ligand has been reported previously, show-
ing that reduction to gold(I) or elemental gold is not predominant
when starting from gold(III) precursors, whereas polymeric
products are generally formed when gold(I) precursors are
used.11
investigated to a relatively limited extent. Mononuclear com-
plexes have been described for the group V to group VIII
transition metals1-8 as well as for samarium,9 tin,9 and nickel.4
Here, we describe reactions of H2L1 and H3L2 with (Bu4N)-
[AuCl4], [Au(Ph3P)Cl], and the organometallic gold(III) complex
[Au(damp-C1,N)Cl2] (1) (damp- ) 2-(N,N-dimethylamino-
methyl)phenyl). The [Au(damp)] moiety has been shown to
stabilize gold(III) with a wide range of coligands including
thiolates and phosphines.12-14
* To whom correspondence should be addressed, E-mail: abram@
chemie.fu-berlin.de.
† University of Tu¨bingen.
‡ Present address: University of Zu¨rich, Institute of Inorganic Chemistry,
Winterthurerstrasse 190, CH-8057 Zu¨rich, Switzerland.
§ University of Oxford.
| Freie Universita¨t Berlin.
(1) Block, E.; Gernon, M.; Kang; H.; Ofori-Okai, G.; Zubieta, J. Inorg.
Chem. 1991, 30, 1736.
(2) Dilworth, J. R.; Hutson, A. J.; Lewis, J. S.; Miller, J. R.; Zheng, Y.;
Chen, Q.; Zubieta, J. J. Chem. Soc., Dalton Trans. 1996, 1093.
(3) Hsu, H.; Koch, S. A.; Popescu, C. V.; Munck, E. J. Am. Chem. Soc.
1997, 119, 8371.
(4) Dao, H. N.; Hsu, H.; Miller, M.; Koch, S. A. J. Am. Chem. Soc.
1996, 118, 8963.
(5) Dilworth, J. R.; Griffith, D. V.; Parrot, S. J.; Zheng, Y. J. Chem. Soc.,
Dalton Trans. 1997, 2931.
(6) Perez-Lourido, P.; Romero, J.; Garcia-Vazquez, J.; Sousa, A.; Maresca,
K. P.; Rose, D. J.; Zubieta, J. Inorg. Chem. 1998, 37, 3331.
(7) De Vries, N.; Davison, A.; Jones, A. G. Inorg. Chim. Acta 1989, 165,
9.
(8) De Vries, N.; Cook, J.; Jones, A. G.; Davison, A. Inorg. Chem. 1991,
30, 2662.
(9) Froelich, N.; Hitchcock, P. B.; Hu, J.; Lappert, M. F.; Dilworth, J. R.
J. Chem. Soc., Dalton Trans. 1996, 1941.
(10) Franolic, J. D.; Yu, W.; Millar, M. J. Am. Chem. Soc. 1992, 114,
6587.
(11) Dilworth, J. R.; Hutson, A. J.; Zubieta, J.; Chen, Q. Transition Met.
Chem. 1994, 19, 61.
(12) Vicente, J.; Chicote, M. T.; Bermudez, M. D.; Jones, P. G.; Fittschen,
C.; Sheldrick, G. M. J. Chem. Soc., Dalton Trans. 1986, 2361.
(13) Parish, R. V.; Howe, B. P.; Wright, J. P.; Mack, J.; Pritchard, R. G.;
Buckley, R. G.; Elsome, A. M.; Fricker, S. P. Inorg. Chem. 1996, 35,
1666.
10.1021/ic000015y CCC: $19.00 © 2000 American Chemical Society
Published on Web 05/27/2000

2802 Inorganic Chemistry, Vol. 39, No. 13, 2000
Ortner et al.
(43%). Found: C, 54.8; H, 4.1. Anal. Calcd for C36H29AuP2S2: C, 55.0;
H, 3.7. IR (νmax/cm-1) 1572,1542 s (CdC), 1436, s (P-phenyl). FAB+
MS (m/z, %, assignment): 785 (36, [Au(Ph3P){PhP(C6H4S)(C6H4-
SH)}]+).
[Au{P(C6H4-S-2)3}]2 (6). [(Ph3P)AuCl] (104 mg, 0.21 mmol) and
P(C6H4-SH-2)3 (H3L2) (25 mg, 0.07 mmol) were dissolved in CH2Cl2
(5 mL) and stirred in air for 1 h. The volume was reduced to about 1
mL, and the yellow solution was stoppered and kept for crystallization.
Insoluble red crystals of 6 appeared on the glass walls over a period of
several days. They were filtered off and washed with CH2Cl2. Yield:
33 mg, 28%. Found: C, 40.2; H, 2.4. Anal. Calcd for C36H24Au2P2S6:
C, 39.1; H, 2.2. IR (νmax/cm-1): 1568 s (CdC), 747 (phenyl).
X-ray Structure Determinations. Single crystals suitable for X-ray
crystallography were taken directly from the reaction mixture (5 and
6) or were obtained by slow diffusion of n-hexane into a CH2Cl2
solution of complex 4.
Intensities for the X-ray structure determinations were collected on
an automated single-crystal diffractometer of type CAD4 or DIP2000
(both Enraf-Nonius, Delft) with Mo KR (λ ) 0.710 73 Å) or Cu KR
(λ ) 1.541 84 Å) radiations at a temperature of -65 °C. HELENA17
and DENZO18 were used for data reduction. An empirical absorption
correction (ψ scans) was applied to the CAD4 data set. The structures
were solved by direct methods using SHELXS97.19 Subsequent Fourier-
difference map analyses yielded the positions of the non-hydrogen
atoms. Refinement was performed using SHELXL97.20 Hydrogen atoms
have been included at calculated positions and treated using the “riding
model” option of SHELXL97. Crystal data and more details of the
data collections and refinements are contained in Table 1. Additional
information on the structure determinations of compounds 2 and 3 is
contained in ref 21 and has been deposited with the Fachinforma-
tionszentrum Karlsruhe as CSD 410274 (2) and CSD 410275 (3).
Experimental Section
Au(damp-C1,N)Cl2]14 and [Au(Ph3P)Cl]15 were prepared using
literature procedures. (Bu4N)[AuCl4] was obtained by addition of an
excess of (Bu4N)Cl to an aqueous solution of HAuCl4 and subsequent
recrystallization from CH2Cl2. PhP(C6H3-SH-2-R-3)2 (R ) H, SiMe3)
(H2L1) and P(C6H4-SH-2)3 (H3L2) were synthesized according to ref
16. IR spectra were recorded on a Perkin-Elmer Spectrum 1000 and
FAB mass spectra obtained using a TSQ 70 (FINNIGAN MAT)
instrument with nitrobenzyl alcohol as the matrix (8 keV, xenon). Fast-
atom bombardment (FAB) mass spectra with m/z > 1000 and field
desorption (FD) spectra were recorded on a TSQ (FINNIGAN MAT
711A). Electrospray (ES) mass spectra were obtained using an API III
TAGA 6000E triple-quadrupole mass spectrometer (Sciex, Canada).
Preparation of Compounds. [Au{PhP(C6H3-S-2-SiMe3-3)2}Cl]
(2) and [Au2{PhP(C6H3-S-2-SiMe3-3)2}2] (3). [Au(damp-C1,N)Cl2]
(200 mg, 0.5 mmol) was dissolved in acetone (3 mL), and PhP(C6H3-
SH-2-SiMe3-3)2 (H2L1a) (235 mg, 0.5 mmol) dissolved in CH2Cl2 (2
mL) was added. The clear, orange-red solution was stirred for 30 min
and reduced in volume. A small amount of red blocks crystallized from
this solution within 1 h. They were removed by filtration, dried in a
vacuum, and analyzed to be 3. Further concentration of the mother
liquor gave red columns of 2.
Results and Discussion
Yield of 2: 266 mg (76%). Found: C, 41.3; H, 4.1; Cl, 4.9. Anal.
Calcd for C24H29AuPS2Si2Cl: C, 41.4; H, 4.1; Cl, 5.1. IR (νmax/cm-1):
1560, 1540 s (CdC), 1438 s (P-phenyl), 855, 838 s (SiMe3), 308 (Au-
Cl). FAB+ MS (m/z, %, assignment): 485 (30, [Au(PhPC6H3-
SSiMe3)]+), 453 (100, [Au(PhPC6H3SiMe3)]+), 307 (38, [PhPC6H3-
SiMe3)]+). FD-MS in CH2Cl2 (m/z, assignment): 700 (M+).
The potentially tri- and tetradentate phosphinothiolates H2L1
and H3L2 proved to be powerful chelating ligands that are able
to stabilize gold(III) despite the reducing capacity of both
aromatic thiols and phosphines. This may be explained by the
rapid chelation of P and thiolate S donor atoms, which stabilizes
a square-planar d8 complex. Reduction would then be inhibited,
since this would require a considerable rearrangement to give
the linear coordination favored by the d10 configuration of gold-
(I). The nature of the products is primarily controlled by the
gold starting materials used, and the temperature and reaction
time do not play a dominant role.
Monomeric gold(III) compounds of the composition [AuCl-
(L1)] are obtained when [Au(damp-C1,N)Cl2] (1) is used as
precursor. The complete substitution of the organometallic
damp- ligand is unusual and has only been observed during
the complex reaction of 1 with 4-methyl-3-mercapto-1,2,4-
triazole (HSmetriaz), where [AuI(HSmetriaz)2]Cl was one of
the isolated products,22 whereas the Au-C σ bond remains when
the chloro ligands are replaced by thiolates or phosphines.12-14,23
This can also be assumed for the first step of the reaction of
[Au(damp-C1,N)Cl2] with ligands of the type H2L1.
Yield of 3: <5%. Found: C, 42.8; H, 4.1. Anal. Calcd for C48H58-
Au2P2S4Si4: C, 43.3; H, 4.4. IR (νmax/cm-1): 1560, 1540 s (CdC),
1438 s (P-phenyl), 855, 838 s (SiMe3). FAB+ MS (m/z, %, assign-
ment): 1330 (15, [Au2{PhP(C6H3SSiMe3)2}]+, 485 (30, [Au(PhPC6H3-
SSiMe3)]+), 453 (100, [Au(PhPC6H3SiMe3)]+), 307 (38, [PhPC6H3-
SiMe3)]+.
[Au2{PhP(C6H4-S-2)2}2] (4). (Bu4N)[AuCl4] (290 mg, 0.5 mmol)
was dissolved in CH2Cl2 (2 mL), and a solution of PhP(C6H4-SH-2)2
(H2L1b) (235 mg, 0.7 mmol) in CH2Cl2 (2 mL) was slowly added. The
red solution was filtered after being stirred for 30 min, and it was then
kept for crystallization. Tiny red plates were obtained. Yield: 93 mg,
36%. Found: C, 42.6; H, 2.5. Anal. Calcd for C36H26Au2P2S4: C, 41.5;
H, 2.3. IR (νmax/cm-1): 1569, 1550 s (CdC), 1445, 1434, 1419 s
(P-phenyl). FAB+ MS (m/z, %, assignment): 1044 (15, [Au2{PhP-
(C6H4S)2}2]+), 845 (8, [Au{PhP(C6H4S)2}2]+).
[(PPh3)Au{P(C6H4-S-2)2(C6H4-SH-2)}](5). AsolutionofP(C6H4-
SH-2)3 (H3L2) (163 mg, 0.5 mmol) in CH2Cl2 was added to a solution
of [Au(Ph3P)Cl] (247 mg, 0.5 mmol). The reaction mixture changed
from colorless to yellow. After the solution was stirred for 1 h the
solvent was allowed to evaporate slowly, leaving a mixture of red
(compound 4) and yellow crystals (compound 5). This mixture was
extracted with n-hexane in which the yellow compound was soluble.
Slow evaporation of the n-hexane extracts results in yellow, light-
sensitive, luminous crystals. When the reaction is performed with strict
exclusion of air, the formation of 4 can be suppressed. Yield: 170 mg
(17) Spek, A. PLATON and HELENA, programs for data reduction and
handling of crystal structure data; University of Utrecht: Utrecht,
The Netherlands, 1997.
(18) Otwinowski, Z.; Minor, W. Processing of X-ray diffraction data
collected in oscillation mode. In Methods in Enzymology; Carter, C.
W., Sweet, R. M., Eds.; ; Academic Press: London, 1996; Vol. 276.
(19) Sheldrick, G. M. SHELXS97, a program for the solution of crystal
structures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(20) Sheldrick, G. M. SHELXL97, a program for the refinement of crystal
structures; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
(21) Ortner, K.; Hilditch, L.; Dilworth, J. R.; Abram, U. Inorg. Chem.
Commun. 1998, 1, 469.
(14) Abram, U.; Mack, J.; Ortner, K.; Mu¨ller, M. J. Chem. Soc., Dalton
Trans. 1998, 1011.
(15) Brauer, G. Handbuch der pra¨paratiVen anorganischen Chemie; Enke
Verlag: Stuttgart, 1981; Vol. 3, p 2019.
(22) Ortner, K.; Mu¨ller, M.; Abram, U. Manuscript in preparation.
(23) Mack, J.; Ortner, J.; Abram, U.; Parish, R. V. Z. Anorg. Allg. Chem.
1997, 623, 873.
(16) Block, E.; Ofori-Okai, G.; Zubieta, J. A. J. Am. Chem. Soc. 1989, 11,
2327.

Gold Complexes
Inorganic Chemistry, Vol. 39, No. 13, 2000 2803
Table 1. X-ray Structure Data Collection and Refinement Parameters
[Au2{PhP(C6H4-S-2)2}2]CH2Cl2 (4)
[(PPh3)Au{P(C6H4-S-2)2(C6H4-SH-2)] (5)
[Au{P(C6H4-S-2)3}]2 (6)
cryst size [mm3]
0.3 × 0.2 × 0.15
C37H28Cl2P2S4Au2
1127.61
cubic
0.8 × 0.4 × 0.3
C36H29P2S2Au
784.62
monoclinic
P21/c
-120
Mo KR, 0.710 73
11.833(1)
18.158(1)
14.909(1)
90
102.58(1)
90
0.15 × 0.05 × 0.05
C36H24P2S6Au2
1104.79
monoclinic
P21/n
formula
fw [g mol-1
cryst syst
]
space group
temp [°C]
radiation λ [Å]
a [Å]
b [Å]
c [Å]
R (deg)
â (deg)
γ (deg)
V [Å3]
Fd3c
-60
-60
Mo KR, 0.710 73
49.678(8)
49.678(8)
49.678(8)
90
Cu KR, 1.541 84
10.422(2)
14.163(2)
11.364(2)
90
94.48(1)
90
90
90
122600(34)
96
3126.4(4)
4
1.667
1672.2(6)
2
2.194
Z
D
calc [g cm-3
]
1.466
µ [mm-1
measd reflns
]
6.09 (Mo KR)
4.966 (Mo KR)
20.88 (Cu KR)
14 084
11 383
3638
independent reflns
obsd reflns
no. parameters
R1(F)/wR2(F2)a
GOF
3236
6010
2833
1830
5311
1688
236
370
208
0.0582/0.1390
0.913
0.0627/0.1532
1.124
0.0552/0.0866
0.978
a R1 ) |Fo - Fc|/|Fo|; wR2 ) [w(Fo - Fc2)2/(wFo )]-1/2
.
2
2
Figure 1. Structure24 of complex 2 along with the atomic numbering
scheme. H atoms have been omitted for clarity.
The formation of intermediates such as 7 is supported by the
mass spectrometric evidence of gold species in the reaction
mixtures having both phosphinothiolate and damp- coordinated
to gold (e.g., [Au(damp){PhP(C6H3-S-2-SiMe3-3)2}]+ at m/z
) 800 with 95% abundance). In the second step the organo-
metallic ligand is displaced by the chelating tridentate ligand
and complexes of the composition of 2 are formed. The presence
of the organometallic ligand, however, seems to be mandatory
for the formation of mononuclear gold(III) complexes. Reduc-
tion of the gold is obviously inhibited, and the compounds
[AuCl(L1)] are formed in reasonable yields. Partial reduction
of gold and the formation of the mixed-valent complex 3 is
only observed as a side reaction.21 [AuCl{PhP(C6H3-S-2-
SiMe3-3)2}] (2) could be isolated in crystalline form, whereas
with {PhP(C6H4-S-2)2} only a red oil was obtained and all
our attempts to crystallize this compound failed. The spectro-
scopic data of the oil (IR, MS), however, strongly suggest a
composition of [AuCl{PhP(C6H4-S-2)2}].
Table 2. Selected Bond Lengths (Å) and Angles (deg) for
Complex 2
Au-P
Au-S(1)
Au-S(2)
2.227(2)
2.325(2)
2.310(2)
Au-Cl
S(1)-C(12)
S(2)-C(22)
2.352(2)
1.781(6)
1.779(7)
P-Au-S(1)
P-Au-S(2)
P-Au-Cl
86.38(6)
S(1)-Au-Cl
S(2)-Au-Cl
C(11)-P-C(21)
95.70(6)
92.14(6)
117.6(3)
86.82(7)
172.89(6)
168.72(6)
S(1)-Au-S(2)
rings, which lead to deviations of 0.17 Å from a least-squares
plane formed by the donor atoms. The bonding situation is
comparable with that in the [Ni{PhP(C6H4-S-2)2}(SC6H4-Ph-
2)]- anion, another example where a ligand of type H2L1 is
constrained to an almost planar coordination mode by a d8 metal
center.10 Selected bond lengths and angles of [AuCl{PhP(C6H3-
S-2-SiMe3-3)2}] are summarized in Table 2.
The reduction of gold and the formation of mixed-valent gold-
(I)/gold(III) complexes is negligible when (1) is used as
precursor but becomes dominating when [AuCl4]- is used.
Obviously, intermediates of the composition 8 can act as
“monodentate thiol” and reduce gold(III) partially to gold(I)
species, which can bind to gold(III) building blocks to give
dimeric and oligomeric species. Mass spectrometric studies of
reaction mixtures containing [AuCl4]- and PhP(C6H4-SH-2)2
The structure of [AuCl{PhP(C6H3-S-2-SiMe3-3)2}] (2)
(Figure 1) shows a distorted square coordination environment
for the gold atom. The primary source of the distortion is the
presence of the pyramidal phosphorus atom and constraints due
to the aromatic backbones in the tridentate ligand, which almost
invariably occupies facial sites in octahedral complexes. The
C(11)-P-C(21) angle of 117.6° at the sp3-hybridized P atom
reflects considerable strains inside the five-membered chelate

2804 Inorganic Chemistry, Vol. 39, No. 13, 2000
Ortner et al.
(H2L1b) give evidence for the formation of [Au3L1b4] (m/z )
1887), [Au3L1b3] (m/z ) 1563), [Au2L1b3] (m/z ) 1367),
[Au3L1b2] (m/z ) 1239), and [Au2L1b2] (m/z ) 1043) units. A
compound of the composition [Au2L1b2] (4) has been isolated
in crystalline form. Its structure (Figure 2) corresponds to that
of the mixed-valence side-product of the reaction of [Au(damp-
C1,N)Cl2] with L1a.21 Selected bond lengths and angles of the
binuclear complex are given in Table 3. The square-planar gold-
(III) coordination site shows a maximum deviation of 0.031(6)
Å from a least-squares plane formed by the donor atoms. The
gold atom is displaced from this plane by 0.080(3) Å toward
Au(2), which has a linear coordination environment comprising
two thiolate groups as expected for a gold(I) center. The Au-
(1)-S(1) bond is slightly longer than the Au(2)-S(2) bond,
which can be attributed to a higher extent of strain in the square
environment of Au(1) compared with the linear coordination
of Au(2). The Au-Au distance of 2.978(2) Å is comparable
with values found in other bi- or multinuclear gold com-
pounds25,26 and is consistent with a bonding “aurophilic”
interaction. This is remarkable because Au(1) doubtlessly
represents a gold(III) site and both gold atoms are elongated
from their ideal coordination environments toward each other.
The linear S(2)-Au(2)-S(2)′ unit is in an eclipsed arrangement
relative to the P-Au-P′ vector with a deviation of only 2.5°,
as is illustrated in 9. Examples for the stabilization of gold(III)
Figure 2. Structure24 of complex 4 along with the atomic numbering
scheme. H atoms have been omitted for clarity.
Table 3. Selected Bond Lengths (Å) and Angles (deg) for
Complex 4a
Au(1)-P
Au(1)-S(1)
Au(2)-S(2)
2.342(4)
2.345(4)
2.295(5)
S(1)-C(12)
S(2)-C(2)
Au(1)-Au(2)
1.76(2)
1.81(2)
2.978(2)
P-Au(1)-P′
P-Au(1)-S(1)
P-Au(1)-S(1)′
174.6(2)
87.1(2)
92.8(2)
S(1)-Au(1)-S(1)′
S(2)-Au(2)-S(2)′
177.6(2)
169.9(3)
a Symmetry code: (′) 1.5 - x, 1 - z, 1 - y.
extremely air-sensitive, whereas the mixed-valence phosphi-
nothiolato complexes do not undergo any reactions in air.
Gold(I) species containing phosphinothiolates can be obtained
when [Au(Ph3P)Cl] is used as a precursor. The reaction of H2L1b
with [Au(Ph3P)Cl] initially gives a small amount of red
crystalline 4, and over the course of a few hours yellow
luminescent crystals of the three-coordinate gold(I) species [Au-
(Ph3P)(HL1b)] (5) form as the major product.
and gold (I) in the same molecule are rare. To our knowledge
there is only one structural report of a comparable compound,
Au4Cl8 (10).27 Four chloro ligands act as bridges between two
The gold atom in [Au(Ph3P)(HL1b)] is coordinated by the two
P atoms and one of the thiolato groups of the phosphinothiol in
a distorted trigonal arrangement (Figure 3). The second thiol
group remains protonated and does not contribute to the
coordination sphere of the metal (distance H(2)-Au: ∼3.2 Å).
Compound 5 is the first three-coordinate gold(I) complex having
a P,S,P coordination sphere. Selected bond lengths and angles
are summarized in Table 4. The deviations of the coordination
sphere of gold from a regular trigonal planar geometry are
mainly due to the restricted bite angle of the chelating PS ligand
(86.0(1)°), which results in P(2)-Au-P(1)/S(1) angles of 129.9-
(1) and 143.5(1)°, respectively. This is comparable with the
situation in [Au(Ph3P)(bipy)]+,28 [Au(PhMe2P)(MSe4)]- (M )
Mo, W) complexes,29 or [Au(Ph3P)(dmit)]- (dmit2- ) 4,5-
gold(I) and two gold(III) centers in this compound. The
Au(I)-Au(I) distance is 3.02 Å. Au4Cl8 is described as
(24) Keller, E. SCHAKAL97sA programme for the graphical presentation
of crystal structures; University of Freiburg: Freiburg, Germany, 1997.
(25) Housecroft, C. E. Coord. Chem. ReV. 1997, 164, 161 and references
therein.
(26) Zank, J.; Schier, A.; Schmidbauer, H. J. Chem. Soc., Dalton Trans.
1998, 323.
(27) D’Amico, B.; Calderazzo, F.; Marchetti, F.; Merlino, S.; Perego, G.
J. Chem. Soc., Chem. Commun. 1977, 31.

Gold Complexes
Inorganic Chemistry, Vol. 39, No. 13, 2000 2805
Figure 3. Structure24 of complex 5 along with the atomic numbering
scheme. Carbon H atoms have been omitted for clarity.
Figure 4. Structure24 of complex 6 along with the atomic numbering
scheme. H atoms have been omitted for clarity.
Table 4. Selected Bond Lengths (Å) and Angles (deg) for
Complex 5
Au-P(1)
Au-P(2)
Au-S(1)
2.399(2)
2.284(2)
2.358(3)
S(1)-C(12)
S(2)-C(22)
1.81(1)
1.71(1)
Compound 6 is practically insoluble in all organic solvents.
Figure 4 shows the molecular structure of the complex. Selected
bond lengths and angles are given in Table 5. Two thiolato
functions and the phosphorus atom of (L2)3- bind to one gold-
(III) center, whereas the third thiolate site forms a bridge to the
second gold atom. The two square-planar coordination spheres
are in an eclipsed arrangement with S-Au-Au-S and S-Au-
Au-P dihedral angles of 11.15° and 5.67°, respectively. The
gold atoms are elongated from the least-squares planes formed
by their donor atoms by 0.138 Å toward each other, resulting
in an Au-Au distance of 3.43 Å, which is in the range of the
sum of their van der Waals radii.32 This is remarkable for two
gold(III) units and indicates weak interactions between the metal
atoms. The structure of 6 can be compared with the binuclear
nickel(II) complex [Ni2(L2)2]2- (12), which can be oxidized to
P(1)-Au-P(2)
P(1)-Au-S(1)
129.9(1)
86.0(1)
P(2)-Au-S(1)
143.5(1)
dimercaptoisotrithione).30 The metal atom is situated 0.097 Å
outside the plane that is formed by P(1), P(2), and S(1). The
Au-P(2) bond length is in the range that has been observed
for other three-coordinate [Au(Ph3P)(L-L)] complexes of gold-
(I).31 No binding Au‚‚‚Au interactions can be detected in the
solid-state structure of 5. The shortest intermolecular Au‚‚‚Au
distance is 7.5 Å.
The formation of a complex with a noncoordinated thiol group
from H2L1b and [Au(Ph3P)Cl] and the unexpected oxidation of
gold(I) to gold(III), which yields 4 where presumably air is the
oxidant, prompted us to attempt similar reactions with H3L2.
From reactions of the potentially tetradentate proligand with
[Au(damp-C1,N)Cl2] or [AuCl4]- we only isolated insoluble
polymeric compounds. With [Au(Ph3P)Cl], however, a yellow
compound was obtained that is readily soluble in dichlo-
romethane when anaerobic conditions are used. Upon concen-
tration of the solution a yellow oil remains, which we assign to
[Au(Ph3P)(H2L2)] (11) on the basis of its mass spectrum.
the mixed-valent Ni(II)/Ni(III) chelate [Ni2(L2)2]- and serves
as model for a strongly chelating, sulfur-containing coordination
environment, as is contained in enzymes such as hydrogenase
All our attempts to crystallize the complex failed. Solutions of
11, however, slowly separate red crystals of 6 when exposed
to air. The yield of the binuclear gold(III) complex is increased
when air is bubbled through the solution at room-temperature.
(30) Cerrada, E.; Jones, P. G.; Laguna, A.; Laguna, M. Inorg. Chem. 1996,
35, 2995.
(31) Gimeno, M. C.; Laguna, A. Chem. ReV. 1997, 97, 511.
(32) Bondi, A. J. Chem. Phys. 1964, 68, 441.
(28) Clegg, W. Acta Crystallogr. 1976, B32, 278.
(29) Salm, R. J.; Misetic, A.; Ibers, J. A. Inorg. Chim. Acta 1995, 240,
239.

2806 Inorganic Chemistry, Vol. 39, No. 13, 2000
Ortner et al.
Table 5. Selected Bond Lengths (Å) and Angles (deg) for
Complex 6a
dramatically illustrated by the gold compounds described in the
present paper.
Au-P
2.282(4)
2.327(4)
2.357(4)
S(1)-C(2)
S(2)-C(12)
S(3)-S(22)
1.76(1)
1.76(2)
1.76(2)
Acknowledgment. We thank DEGUSSA AG for generously
providing us with gold starting materials and gratefully ac-
knowledge financial support from the DAAD, the British
Council and the Fonds der Chemischen Industrie. U.A. and K.O.
additionally thank Professor J. Stra¨hle (Tu¨bingen) for his
hospitality and the opportunity to collect the X-ray data sets
and Dr. R. Su¨ssmuth for the measurement of ES mass spectra.
Au-S(2)
Au-S(3)
Au-S(1)′
P-Au-S(2)
P-Au-S(3)
a Symmetry code: (′) 2-x, -y, 2-z.
2.358(4)
88.0(1)
83.4(1)
Au-Au′
3.434(1)
174.1(1)
159.8(1)
P-Au-S(1)′
S(2)-Au-S(3)
or carbon monoxide dehydrogenase.10 It is interesting to note
that the comparable complex [Ni(L1a)(SC6H4-Ph-2)] (13)
cannot be oxidized to a Ni(III) species.10 This suggests a strong
influence of the chelating capacity of the ligands on their ability
to stabilize high formal oxidation states of metals, and this is
Supporting Information Available: Three X-ray crystallographic
files in CIF format. This material is available free of charge via the
Internet at http://pubs.acs.org.
IC000015Y