High-coordinate gold(I) complexes with dithiocarboxylate ligands

Article abstract of DOI:10.1021/ic500151j

Ferrocene dithiocarboxylate has been introduced into the chemistry of gold(I) and copper(I). First, a modified synthesis of piperidinium ferrocene dithiocarboxylate (1) is reported. Reaction of this reagent with [Au(tht)Cl] in the presence of different phosphines resulted in monomeric, dimeric, and polymeric structures. Although gold(I) is usually two coordinate, mainly three- and four-fold coordinated compounds were obtained by using ferrocene dithiocarboxylate as ligands. The isolated compounds are [(FcCSS)Au(PPh ₃)₂] (2) (FcCSS = ferrocene dithiocarboxylate), [(FcCSS)Au₂(dppm)₂] (3) (dppm = bis(diphenylphosphino) methane), and [(FcCSS)Au(dppf)]_n (4) (dppf = bis(diphenylphosphino) ferrocene) [{(FcCSS)Au}₂(dppp)] (5) (dppp = bis(diphenylphosphino) propane). The FcCSS ligand shows a remarkable flexible coordination mode. It coordinates either in a monodentate, a chelating, or in a metal bridging mode. In the four gold(I) complexes 2-5 four different coordination modes of the FcCSS ligand are seen. Attempts to extend this rich coordination chemistry to other coinage metals were only partly successful. [(FcCSS)Cu(PPh₃) ₂] (6) was obtained from the reaction of piperidinium ferrocene dithiocarboxylate with [(Ph₃P)₃CuCl]. ⁵⁷Fe- Moessbauer spectroscopy was performed for compounds 2-4. The spectra show isomer shifts and quadrupole splittings that are typical for diamagnetic ferrocenes.

Full text of DOI:10.1021/ic500151j

Article
pubs.acs.org/IC
High-Coordinate Gold(I) Complexes with Dithiocarboxylate Ligands
Christoph Kaub,† Timo Augenstein,† Thomas O. Bauer,‡ Elisa Rothe,‡ Lars Esmezjan,†
Volker Schunemann,‡ and Peter W. Roesky*,†
̈
†Institut fur Anorganische Chemie, Karlsruher Institut fur Technologie (KIT), Engesserstrasse 15, 76131 Karlsruhe, Germany
̈
̈
‡Fachbereich Physik, Technische Universitat Kaiserslautern, Erwin-Schrodinger-Strasse 46, 67663 Kaiserslautern
̈
̈
S
* Supporting Information
ABSTRACT: Ferrocene dithiocarboxylate has been introduced into the
chemistry of gold(I) and copper(I). First, a modified synthesis of
piperidinium ferrocene dithiocarboxylate (1) is reported. Reaction of this
reagent with [Au(tht)Cl] in the presence of different phosphines resulted in
monomeric, dimeric, and polymeric structures. Although gold(I) is usually
two coordinate, mainly three- and four-fold coordinated compounds were
obtained by using ferrocene dithiocarboxylate as ligands. The isolated
compounds are [(FcCSS)Au(PPh3)2] (2) (FcCSS = ferrocene dithiocarbox-
ylate), [(FcCSS)Au2(dppm)2] (3) (dppm = bis(diphenylphosphino)methane), and [(FcCSS)Au(dppf)]n (4) (dppf =
bis(diphenylphosphino)ferrocene) [{(FcCSS)Au}2(dppp)] (5) (dppp = bis(diphenylphosphino)propane). The FcCSS ligand
shows a remarkable flexible coordination mode. It coordinates either in a monodentate, a chelating, or in a metal bridging mode.
In the four gold(I) complexes 2−5 four different coordination modes of the FcCSS ligand are seen. Attempts to extend this rich
coordination chemistry to other coinage metals were only partly successful. [(FcCSS)Cu(PPh3)2] (6) was obtained from the
reaction of piperidinium ferrocene dithiocarboxylate with [(Ph3P)3CuCl]. 57Fe−Mossbauer spectroscopy was performed for
̈
compounds 2−4. The spectra show isomer shifts and quadrupole splittings that are typical for diamagnetic ferrocenes.
coordination chemistry. Although some metal salts,40 as well as
INTRODUCTION
■
cyclopentadienyl,41 nitrido,42 and carbonyl complexes43 of
ferrocene dithiocarboxylate have been reported, to the best of
our knowledge no structurally characterized derivative and no
gold complex is known. Thus, ferrocene dithiocarboxylate has
been neglected as ligand. This is surprising since ferrocene
based ligands are widely used, for example, 1,1′-bis-
(diphenylphosphino)ferrocene44 because of their rigid back-
bones in catalytic systems.45 They are also used for the
construction of coordination polymers.46 Ferrocene-containing
compounds have also been studied in terms of their magnetic
and electronic properties.47 Herein, we report the synthesis and
characterization of the first structurally characterized metal
complexes of ferrocene dithiocarboxylate.
The coordination and organometallic chemistry of gold is
currently an emerging field in chemistry.1 The rapid develop-
ment in this area has been summarized in some recent reviews.
It covers the synthesis and applications of gold and gold
compounds in synthesis,2−10 material and surface sciences,11−15
for biological applications,16,17 in heterogeneous cataly-
sis,14,18−22 and especially, in homogeneous catalysis.23−27
Molecular gold(I) compounds with a closed shell d10 electronic
configuration are linearly coordinated in most cases. However,
gold(I) complexes possessing higher coordination numbers also
exist, although they are less common. In particular, high
coordinate gold(I) ions with gold−gold contacts are rare.1
These contacts are commonly a result of strong relativistic
contractions and low coordination numbers. The gold(I) ion is,
according to Pearson’s HSAB concept,28 usually considered a
soft metal ion preferring coordination by soft ligands such as
phosphines, organic sulfur ligands, and N-heterocyclic carbenes
(NHCs). Sulfur containing ligands derived from dithiocarba-
mate29−32 and xanthate33 usually act as monodentate ligands
but in a few cases bidentate coordination to two metal centers
has been reported.29−32 Although it is known that dithiocarbox-
ylates are as flexible in coordination as dithiocarbamates they
are less common in gold(I) chemistry.34−39
EXPERIMENTAL SECTION
■
General Procedures. Although all products are not very air-
sensitive most manipulations were performed with the rigorous
exclusion of oxygen and moisture in flame-dried Schlenk-type
glassware or in an argon-filled MBraun glovebox. Dichloromethane
was distilled from LiAlH4 under nitrogen prior to use. Hydrocarbon
solvents (THF, toluene, and n-pentane) were dried using an MBraun
solvent purification system (SPS-800). Deuterated solvents were
obtained from Carl Roth GmbH (99.5 atom % D). NMR spectra were
recorded on a Bruker Avance II 300 MHz or Avance 400 MHz.
Chemical shifts are referenced to the residue 1H and 13C resonances of
the deuterated solvents and are reported relative to tetramethylsilane
We were interested to introduce ferrocene dithiocarboxylate
as redox active ligand into gold(I) chemistry. Originally we
intended to influence the reactivity and the solubility of the
resulting products. Although ferrocene dithiocarboxylate has
been known as a ligand since 1974,40 it has been rarely used in
Received: January 21, 2014
Published: April 15, 2014
© 2014 American Chemical Society
4491
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
and 85% phosphoric acid (31P NMR). IR spectra were obtained on a
Bruker Tensor 37. Mass spectra were recorded at 70 eV on a Thermo
Scientific DFS and on a IonSpec FT-ICR (7 T) ESI-MS. UV−vis
spectra were recorded on a Varian Cary 50 spectrophotometer. X-ray
powder diffraction patterns (XRD) for different samples of 4 were
measured on a STOE STADI P diffractometer (Cu−Kα radiation,
Germanium monochromator, Debye−Scherrer geometry) in sealed
glass capillaries. The theoretical powder diffraction pattern was
calculated on the basis of the atom coordinates obtained from single
crystal X-ray analysis by using the program package Mercury 3.1 by
CCDC.48 Elemental analyses were carried out with an Elementar Vario
EL or Micro Cube. [Au(tht)Cl]49,50 (tht = tetrahydrothiophene) and
[(PPh3)3CuCl]51 were prepared according to modified standard
procedures.
(w), 993 (m), 955 (w), 913 (w), 836 (w), 811 (m), 744 (s), 705 (m),
691 (s), 668 (m), 618 (w), 531 (m), 515 (s). C47H39AuFeS2P2·0.5
C4H8O (1018.76): calculated C 57.77; H 4.25; S 6.29; found C 57.39;
H 4.27; S 6.22. UV−vis (CH2Cl2): λmax (nm) [εmax (l·mol−1·cm−1)] =
384 (broad) [6509], 531 (very broad) [2441] − (THF) λmax (nm) =
383 (broad), 512 (very broad).
[(FcCSS)Au2(dppm)2]Cl (3). The synthesis was carried out in air.
[Au(tht)Cl] (640 mg, 2.00 mmol) and bis(diphenylphosphino)-
methane (770 mg, 2.00 mmol) were dissolved in dichloromethane (20
mL). A solution of piperidinium ferrrocene dithiocarboxylate (350 mg,
1.00 mmol) in dichloromethane (10 mL) was added dropwise and the
mixture was stirred for 30 min. After washing the solution with water
(3 × 100 mL) and drying over magnesium sulfate, the solvent was
removed in vacuo and the residing solid was washed with ethanol (3 ×
10 mL) and pentane (2 × 10 mL). Yield (red powder): 950 mg, 0.61
mmol, 61.5%. Crystals suitable for X-ray diffraction were grown by
slow diffusion of pentane into a saturated solution of dry dichloro-
Piperidinium Ferrocene Dithiocarboxylate (1). The synthesis was
carried out as described in the literature with slight modifications.40 A
few drops of an ethereal solution (15 mL) of bromo ferrocene (4.00 g,
15.0 mmol) and iodomethane (0.5 mL, 7.5 mmol) were added to
magnesium turnings (1.10 g, 45.0 mmol) in diethyl ether (10 mL).
The Grignard reaction was initiated by adding iodomethane (0.1 mL)
and brief heating of the solvent. The rest of the bromoferrocene
solution was added dropwise and the reaction was stirred for 3 h. To
the resulting orange suspension, carbondisulfide (1.8 mL, 30.0 mmol)
dissolved in THF (50 mL) was added dropwise at 0 °C. After warming
up to room temperature overnight, the reaction mixture was poured
into ice cooled hydrochloric acid (25 mL, 16%) and the product was
extracted with diethyl ether (200 mL). The solvent was removed in
vacuo and the residue was extracted with sodium hydroxide (150 mL,
16%) and water (100 mL). After filtering and acidifying the solution
with hydrochloric acid (100 mL, 32%) at 0 °C, the product was
extracted with diethyl ether (3 × 100 mL). The ether layer was dried
over magnesium sulfate and treated with piperidine (2 mL). The
precipitate was filtered off and washed with diethyl ether. The desired
product was obtained as a red microcrystalline solid (2.90 g, 8.35
1
methane. H NMR (300 MHz, CD2Cl2, 25 °C): δ (ppm) = 7.73 (m,
16H, o-Ph), 7.39 (m, 24H, m-Ph, p-Ph), 5.13 (s, 2H, o-Cp), 4.60 (s,
2H, m-Cp), 4.32 (br. s, 4H, PCH2P), 4.07 (s, 5H, C5H5). 13C{1H}
NMR (75 MHz, CDCl3, 25 °C): δ (ppm) = 133.5 (Ph), 131.8 (Ph),
129.0 (Ph), 71.8 (C5H5). Because of poor solubility, not all carbon
atoms were detected. 31P{1H} NMR (121 MHz, CD2Cl2, 25 °C): δ
(ppm) = 31.3 (s). ESI-MS (CH2Cl2) 1423.15 ([(FcCSS)-
Au (dppm) ]+), 1289.10. IR (ATR): v (cm−1) = 3048 (w), 3011
̃
2
2
(w), 2901 (w), 2843 (w), 2819 (w), 1653 (w), 1574 (w), 1559 (w),
1540 (w), 1484 (w), 1434 (m), 1419 (w), 1392 (w), 1366 (w), 1319
(w), 1275 (w), 1241 (w), 1196 (w), 1168 (w), 1099 (m), 1039 (w),
1027 (w), 998 (m), 979 (w), 836 (w), 823 (m), 796 (m), 784 (m),
737 (m), 723 (m), 688 (s), 665 (m), 616 (w), 508 (w). UV−vis
(CH2Cl2): λmax (nm) [εmax (l·mol−1·cm−1)] = 397 (broad); 548 (very
broad). Because of lattice solvent εmax could not be determined.
C61H53Au2ClFeP4S2·CH2Cl2 (1544.26): calculated C 48.22; H 3.59; S
4.15; found C 48.12; H 3.55; S 4.11.
1
mmol, 55%). H NMR (CDCl3, 300 MHz, 25 °C): δ (ppm) = 7.14
[(FcCSS)Au(dppf)]n (4). Piperidinium ferrocene dithiocarboxylate
(87 mg, 0.25 mmol) and [Au(tht)Cl] (80 mg, 0.25 mmol) were
dissolved in dichloromethane (10 mL) forming a black suspension. A
solution of bis(diphenylphosphino)ferrocene (139 mg, 0.25 mmol) in
dichloromethane (10 mL) was added, and the resulting red solution
was stirred for 1 h. After a few minutes, a red solid started precipitating
which was separated by filtration and washed with dichloromethane (2
× 5 mL). Yield (red powder): 100 mg, 40%. Crystals were grown by
overlaying a solution of piperidinium ferrocenedithiocarboxylate (87
mg, 0.25 mmol) and bis-diphenylphosphinoferrocene (139 mg, 0.25
mmol) in dichloromethane (5 mL) with a solution of [Au(tht)Cl] (80
mg, 0.25 mmol) dissolved in a mixture of dichloromethane (3.5 mL)
and THF (2.5 mL). (C45H37Fe2AuS2P2)n: calculated C 53.38, H 3.68,
S 6.33, found C 53.17, H 3.70, S 6.03. IR (ATR): (cm−1) = 3072 (w),
3051 (w), 1653 (w), 1559 (w), 1479 (w), 1434 (w), 1392 (w), 1310
(w), 1259 (w), 1207 (w), 1168 (w), 1100 (w), 1069 (w), 1041 (w),
1027 (w), 1002 (w), 997(w), 958 (w), 821 (w), 811 (w), 751 (w), 739
(w), 696 (w), 667 (m), 637 (m), 619 (w), 540 (m), 513 (m).
[{(FcCSS)Au}2(dppp)] (5). Bis(diphenylphosphino)propane (124
mg, 0.30 mmol) and [Au(tht)Cl] (192 mg, 0.60 mmol) were
dissolved in dichloromethane (15 mL) and stirred for 30 min.
Piperidinium ferrocene dithiocarboxylate (208 mg, 0.6 mmol) was
added. After stirring for another 30 min, the solvent was removed in
vacuo and the residue was dissolved in THF. The insoluble
piperidinium hydrochloride was separated by filtration. The solvent
was removed in vacuo and the solid was suspended in pentane (2 mL).
Dichloromethane was added until a clear solution had formed which
was stored for 12 days at −20 °C. Yield (red crystals): 119 mg; 0.091
(br. s, 2H, NH2), 5.32 (m, 2H, o-Cp), 4.54 (m, 2H, m-Cp), 4.19 (s,
5H, C5H5), 3.27 (m, 4H, pip-NCH2), 1.85 (m, 4H, pip−CH2), 1.62
(m, 2H, pip−CH2). 13C{1H} NMR (CDCl3, 75 MHz, 25 °C): δ
(ppm) = 253.9 (CSS), 94.8 (i-Cp), 72.2 (o-Cp), 71.5 (m-Cp), 71.4
(C5H5), 45.2 (pip-NC), 23.1 (pip-NCC), 22.4 (pip-CH2). UV−vis
(CH2Cl2): λmax (nm) [εmax (l·mol−1·cm−1)] = 310 (sharp) [11918];
335 (shoulder) [6297]; 529 (broad) [1462]. The analytical data
matches with the literature.40 C16H21NFeS2 (347.33): calculated C
55.33, H 6.09, N 4.03, S18.46; found C 54.86, H 6.10, N 3.93, S 18.48.
[(FcCSS)Au(PPh3)2] (2). The synthesis was carried out in air.
[Au(tht)Cl] (162 mg, 0.50 mmol) and triphenylphosphine (264 mg,
1.00 mmol) were dissolved in dichloromethane (10 mL). A solution of
piperidinium ferrrocene dithiocarboxylate (175 mg, 0.50 mmol) in
dichloromethane (5 mL) was added dropwise and the mixture was
stirred for 30 min at room temperature. After washing the solution
with water (3 × 20 mL) and drying over magnesium sulfate, the
solvent was removed in vacuo and the residue was washed with
ethanol (3x 10 mL) and pentane (2 × 10 mL). To achieve a higher
purity the reaction mixture was removed and the residue was dissolved
in dry THF (3.5 mL). After the filtration, the product was crystallized
by slow diffusion of pentane into the solution. Yield (red crystals): 298
1
mg, 0.29 mmol, 58%. H NMR (300 MHz, C6D6, 25 °C): δ (ppm) =
7.46 (m, 12H, o-Ph), 6.96 (m, 18H, m-Ph, p-Ph), 5.53 (m, 2H, o-Cp),
4.25 (m, 2H, m-Cp), 4.17 (s, 5H, C5H5), 3.56 (m, 4H, THF−
OCHH2), 1.41 (m, 4H, THF−OCHH2CH2). 13C{1H} NMR (75
MHz, C6D6, 25 °C): δ (ppm) = 247.3 (CSS), 134.0 (d, JPC = 16.2 Hz,
Ph), 133.7 (Ph), 129.8 (d, JPC = 1.4 Hz, Ph), 128.6 (d, JPC = 9.5 Hz,
Ph), 94.1 (i-Cp), 72.0 (o-Cp), 71.7 (C5H5), 71.2 (m-Cp), 67.5 (THF-
OC), 25.5 (THF−OCHC). 31P{1H} NMR (121 MHz, C6D6, 25 °C):
δ (ppm) = 20.4 (s). EI-MS (70 eV): m/z (%) = 720 [M − PPh3]+, 656
[M − PPh3 − C5H5]+, 552, 538, 534, 504, 490, 470, 428, 426, 396,
394, 372, 368, 362, 294, 262 [PPh3]+, 215, 183, 139, 107, 77. IR
1
mmol, 28%. C49H44Au2Fe2P2S4·CH2Cl2. H NMR (300 MHz, CDCl3,
25 °C): δ (ppm) = 7.84 (m, 8H, o-Ph), 7.47 (m, 12H, m-Ph, p-Ph),
5.34 (s, 2H, DCM), 5.21 (m, 2H, o-Cp), 4.61 (m, 2H, m-Cp), 4.27 (s,
10H, C5H5), 2.99 (m, 4H, PCH2), 1.98 (m, 2H, CH2). 13C{1H} NMR
(100 MHz, CD2Cl2, 25 °C): δ (ppm) = 246.4 (CSS), 133.7 (d, 1JPC
=
(ATR): v (cm−1) = 3051 (w), 2966 (w), 2857 (w), 1585 (w), 1478
13.3 Hz, i-Ph), 131.8 (d, 2JPC = 2.5 Hz, o-Ph), 130.0 (d, 3JPC = 54.7 Hz,
̃
(m), 1432 (m), 1395 (w), 1378 (w), 1329 (w), 1307 (w), 1256 (m),
m-Ph), 129.4 (d, 4JPC = 11.3 Hz, p-Ph), 93.1 (i-Cp), 72.7 (o-Cp), 71.9
1
3
1205 (w), 1182 (m), 1157 (w), 1095 (m), 1064 (w), 1045 (w), 1026
Cp, 71.3 (m-Cp), 28.2 (dd, JPC = 34.2 Hz, JPC = 10.2 Hz, PC), 19.7
4492
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
Scheme 1. Synthesis of Piperidinium Ferrocene Dithiocarboxylate
3
(t, JPC = 2.5 Hz, PCC). 13C{1H, 31P} NMR (100 MHz, CD2Cl2, 25
95.82(3)°, γ = 113.23(3)°, V = 2227.9(9) Å3, T = 173(2) K, space
°C): δ (ppm) = 133.7 (i-Ph), 131.8 (o-Ph), 130.0 (m-Ph), 129.4 (p-
Ph), 93.4 (i-Cp), 72.8 (o-Cp), 72.0 (C5H5), 71.3 (m-Cp), 28.2 (PCC),
19.7 (PCC). 31P{1H} NMR (121 MHz, C6D6, 25 °C): δ (ppm) =
−27.5. IR (ATR): (cm−1) = 1483 (w), 1443 (w), 1436 (w), 1426 (w),
1408 (w), 1397 (w), 1375 (w), 1256 (m), 1205 (w), 1133 (w), 1105
(w) 1059 (w), 1046 (w), 1034 (w), 1026 (w), 995 (m), 939 (w), 837
(w), 820 (w), 797 (m), 774 (w), 750 (w), 738 (m), 714 (w), 699 (w),
688 (m), 665 (w), 651 (w), 616 (w), 590 (w), 529 (w), 513 (m), 496
(s), 476 (m), 457 (w). UV−vis (CH2Cl2): λmax (nm) [εmax (l·mol−1·
cm−1)] = 386 (broad); 530 (very broad). Because of the lattice
solvent, εmax could not be determined. C49H44P2S4Fe2Au2 (1328.73):
calculated C 44.29, H 3.34, S 9.65; found C 42.97, H 3.33, S 9.24. In
the elemental analysis we frequently observed low carbon values.
[(FcCSS)Cu(PPh3)2] (6). [(PPh3)3CuCl] (443 mg, 0.50 mmol) and
piperidinium ferrocenedithiocarboxylate (175 mg, 0.50 mmol) were
dissolved in dichloromethane (15 mL) and the mixture was stirred for
2 h. The solvent was removed in vacuo and the residue was dissolved
in THF (4 mL). After filtration, the product was crystallized by slow
diffusion of pentane into the solution. Yield (red crystals): 381 mg,
0.41 mmol, 83%. 1H NMR (300 MHz, C6D6, 25 °C): δ (ppm) = 7.55
(m, 12H, o-Ph), 6.95 (m, 18H, m-Ph, p-Ph), 5.49 (m, 2H, o-Cp), 4.22
(m, 2H, m-Cp), 4.13 (s, 5H, C5H5), 3.56 (m, 4H, THF−OCHH2),
1.40 (m, 4H, THF−OCHCH2). 13C{1H} NMR (75 MHz, CDCl3, 25
°C): δ (ppm) = 249.0 (CSS), 134.2 (Ph), 133.8 (Ph), 129.5 (Ph),
128.4 (Ph), 92.2 (i-Cp), 71.5 (o-Cp), 71.3 (C5H5), 69.7 (m-Cp), 68.0
(THF-OC), 25.7 (THF−OCHC). 31P{1H} NMR (121 MHz, C6D6,
25 °C): δ (ppm) = −0.8 (s). IR (ATR): v;∼ (cm−1) = 3049 (w), 1699
(w), 1653 (w), 1584 (w), 1558 (w), 1540 (w), 1478 (w), 1432 (m),
1376 (w), 1327 (w), 1308 (w), 1260 (w), 1204 (w), 1182 (w), 1156
(w), 1092 (w), 1067 (w), 1042 (w), 1026 (m), 993 (w), 920 (w), 871
(w), 838 (w), 813 (w), 742 (m), 692 (s), 667 (w), 618 (w), 526 (m),
516 (m). C47H39CuFeP2S2 (849.29): calculated C 66.47; H 4.63; S
7.55; found C 65.60; H 4.77; S 7.00. C47H39CuFeP2S2·C4H8O
Electrochemistry. Cyclic voltammetry measurements were per-
formed with an METROHM potentiostat (PGSTAT 101) and an
electrochemical cell for sensitive compounds. We used a freshly
polished Pt disk working electrode, a Pt stick as the counter electrode,
and a Ag wire as (pseudo) the reference electrode ([nBu4N][PF6] (0.1
M) as electrolyte). Potentials were calibrated against the Fc/Fc+
couple, which has a potential of E01/2 = 0.35 V vs Ag/AgCl (Supporting
Information Figures S3−S5).
group P1, Z = 2, μ(MoKα) = 3.814 mm−1, 22187 reflections
̅
measured, 7951 independent reflections (Rint = 0.0395). The final R1
values were 0.0310 (I > 2σ(I)). The final wR(F2) values were 0.1051
(all data). The goodness of fit on F2 was 1.092.
Crystal data for 3: [C61H53Au2FeP4S2]Cl, M = 1459.26, a =
11.6660(3) Å, b = 22.0215(4) Å, c = 23.4212(5) Å, β = 95.948(2)°, V
= 5984.6(2) Å3, T = 150(2) K, space group P21/n, Z = 4, μ(MoKα) =
5.388 mm−1, 32828 reflections measured, 11255 independent
reflections (Rint = 0.0417). The final R1 values were 0.0308 (I >
2σ(I)). The final wR(F2) values were 0.0687 (all data). The goodness
of fit on F2 was 0.923.
Crystal data for 4: C45H37AuFe2P2S2·2(CH2Cl2), M = 1109.47, a =
11.104(2) Å, b = 26.986(5) Å, c = 17.106(3) Å, β = 107.65(3), V =
4884(2) Å3, space group P21/c, Z = 4.
Crystal data for 4′: C45H37AuFe2P2S2, M = 1012.47, a = 11.040(2)
Å, b = 21.488(4) Å, c = 17.106(3) Å, β = 107.62(3)°, V = 3874.6(15)
Å3, space group P21/n, Z = 4.
Crystal data for 5: C49H44Au2Fe2P2S4·0.25 CH2Cl2, M = 1349.88, a
= 15.180(3) Å, b = 20.750(4) Å, c = 16.740(3) Å, β = 105.80(3)°, V =
5074(2) Å3, T = 200(2) K, space group P21/n, Z = 4, μ(MoKα) =
6.612 mm−1, 46244 reflections measured, 6235 independent
reflections (Rint = 0.0876). The final R1 values were 0.0485 (I >
2σ(I)). The final wR(F2) values were 0.1252 (all data). The goodness
of fit on F2 was 0.936.
Crystal data for 6: C47H39CuFeP2S2·C4H8O, M = 921.33, a =
10.780(2) Å, b = 13.154(3) Å, c = 19.292(4) Å, α = 95.35(3)°, β =
100.13(3)°, γ = 94.48(3)°, V = 2668.6(10) Å3, T = 200(2) K, space
group P1, Z = 2, μ(MoKα) = 0.840 mm−1, 17611 reflections
̅
measured, 9393 independent reflections (Rint = 0.0368). The final R1
values were 0.0377 (I > 2σ(I)). The final wR(F2) values were 0.0945
(all data). The goodness of fit on F2 was 0.862.
Crystallographic data (excluding structure factors) for the structures
reported in this paper have been deposited with the Cambridge
Crystallographic Data Centre as a supplementary publication no.
976102 (2), 976103(3), 976104 (5), and 976105(6). Copies of the
data can be obtained free of charge on application to CCDC, 12 Union
Road, Cambridge CB21EZ, U.K. (fax: (+(44)1223−336−033; email:
deposit@ccdc.cam.ac.uk).
̈
Mossbauer Spectroscopy. Mossbauer spectra were recorded using
̈
a conventional spectrometer in the constant-acceleration mode using
both a continuous flow cryostat (Oxford Instruments) and a closed
cycle cryostat equipped with a superconducting magnet as described
earlier.53 Isomer shifts are given relative to α-Fe at room temperature.
The spectra were analyzed by least-squares fits using Lorentzian line
X-ray Crystallographic Studies of 2−6. A suitable crystal was
covered in mineral oil (Aldrich) and mounted on a glass fiber. The
crystal was transferred directly to the cold stream of a STOE IPDS 2
diffractometer.
All structures were solved by the Patterson method (SHELXS-
9752). The remaining non-hydrogen atoms were located from
difference in Fourier map calculations. The refinements were carried
out by using full-matrix least-squares techniques on F, minimizing the
shapes.54 Mossbauer spectra obtained under high magnetic fields were
̈
simulated by means of the spin Hamiltonian formalism which enables
full diagonalization of the nuclear Hamiltonian and subsequent powder
averaging.54,55
2
2
function (F0 − Fc)2, where the weight is defined as 4F0 /2(F0 ) and F0
and Fc are the observed and calculated structure factor amplitudes
using the program SHELXL-97.52 Carbon-bound hydrogen atom
positions were calculated. The locations of the largest peaks in the final
difference Fourier map calculation as well as the magnitude of the
residual electron densities in each case were of no chemical
significance. Positional parameters, hydrogen atom parameters,
thermal parameters, bond lengths and angles have been deposited as
Supporting Information.
RESULTS AND DISCUSSION
■
Piperidinium ferrocene dithiocarboxylate (1) was synthesized
by a modified literature procedure40 starting from bromoferro-
cene, which was reacted with magnesium to give the
corresponding Grignard reagent. In contrast to the literature
procedure,40 the reaction was run without cooling and the
extraction steps were slightly modified. Treatment of this
reagent with carbondisulfide resulted in the formation of
ferrocene dithiocarboxylate, which was treated with piperidine
to give 1 in moderate yield (Scheme 1).
Crystal data for 2: C47H39AuFeP2S2·0.5(C4H8O), M = 1018.71, a =
12.348(3) Å, b = 13.089(3) Å, c = 15.366(3) Å, α = 97.82(3)°, β =
4493
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
To obtain gold(I) complexes, 1 was treated with [Au(tht)-
Cl]. This resulted in a blue solution. After some time, a black
insoluble polymeric species precipitated out of this solution. To
avoid polymer formation different phosphines were reacted
with [Au(tht)Cl] before 1 was added. For the formation of
complexes, it was found that the order, in which the reactants
are added to the reaction mixture, does not matter. Thus, the
reaction of 1 with [Au(tht)Cl] and triphenylphosphine at room
temperature in CH2Cl2 resulted in a red solution. After work-
up, the iron/gold compound [(FcCSS)Au(PPh3)2] (2) (FcCSS
= ferrocene dithiocarboxylate) was obtained as red crystals
(Scheme 2). In compound 2, the gold(I) atom is surrounded
by the ferrocene dithiocarboxylate and two triphenylphosphine
ligands.
Figure 1. Molecular structure of 2 (front and side view). Hydrogen
atoms and solvent molecules have been omitted for clarity. Selected
bond lengths (Å) and angles (deg): Au−P1 2.323(2), Au−P2
2.308(2), Au−S1 2.583(2), Au−S2 2.808(2), S1−C11 1.706(7),
S2−C11 1.6707(7); P1−Au−P2 132.04(6), S1−Au−S2 66.13(6),
P1−Au−S1 107.79(6), P1−Au−S2 103.23(6), P2−Au−S1 118.74(6),
P2−Au−S2 105.43(6), S1−C11−S2 121.6(4).
Scheme 2. Synthesis of 2
compound [(FcCSS)Au2(dppm)2] (3) was obtained in
moderate yield (Scheme 3). Complex 3 is a bimetallic gold(I)
complex in which the gold atoms are bridged by two dppm
ligands and one ferrocene dithiocarboxylate ligand. Further-
more, an Au−Au interaction is observed which results in highly
coordinated gold(I) atoms. Complex 3 resembles a bicyclic
structure, in which the gold atoms are located in the bridgehead
position. Obviously, the dithiocarboxylate ligand adopts a very
flexible coordination mode. The slight change within the
geometry of the donating phosphine ligand results in a
complete change of the coordination environment of the
gold(I) atoms. Thus, a monodentate coordination mode with a
secondary interaction (compound 2) and a metal bridging
coordination mode (compound 3) are observed, although the
donating ligand atoms are the same.
Compound 2 was fully characterized by standard spectro-
scopic/analytic techniques. In the 1H NMR spectrum character-
istic signals for the cyclopentadienyl rings were detected. The
unsubstituted ring shows one singlet at δ = 4.17 ppm, whereas
the signals of the other ring were split into two pseudo triplets
at δ = 5.53 and 4.25 ppm. In the 31P{1H} NMR spectrum, the
expected signal is seen at δ = 20.4 ppm (30.1 ppm in
[PPh3AuCl]).56 The quaternary carbon atoms of the CS2 group
(δ = 247.3) and the Cp (δ = 94.1) ring were detected in the
13C{1H} NMR spectrum of 2. The signal of the CS2 group is
shifted to high field in comparison to 1 (δ = 253.9), whereas
the signal of the quarternary Cp carbon atom is not influenced
(δ = 94.8 in 1). Although no molecular peak was detected in
the EI-MS spectrum, the fragments [M − PPh3]+ (m/z = 720)
and [M − PPh3 − C5H5]+ (m/z = 656) were observed.
Compound 3 is air-stable but it decomposes in polar solvents
1
such as DMSO and DMF. H, 13C{1H}, and 31P{1H} NMR
1
spectra were recorded in CH2Cl2. In the H NMR spectrum,
several multiplets for the phenyl groups were observed in the
region of δ = 7.74−7.71 ppm and 7.47−7.30 ppm. The signal of
the nonsubstituted cyclopentadienyl ring (δ = 4.07) is
characteristic. Interestingly, the signal of the P−CH2−P
group is not split into a triplet. Instead, a broad singlet at δ
= 4.32 ppm was observed. A similar behavior was observed in
[dppm(AuCl)2] and the authors suggested a small scalar
Compound 2 crystallized in the triclinic space group P1 with
̅
two molecules of 2 and one molecule of THF in the unit cell.
In contrast to most gold(I) compounds the metal is not linearly
coordinated but instead it is three coordinated. Distorted
trigonal planar coordination is observed. The sum of the angles
P1−Au−P2 132.04(6)°, S1−Au−S2 66.13(6)°, and P1−Au−
S2 103.23(6)°, P2−Au−S1 118.74(6)° is 358.57°, which is
close to the ideal value of 360° for a trigonal planar
arrangement. The P1−Au−P2 angle of 132.04(6)° is in the
range of related dithiocarboxylate compounds, e.g. 137.4(8)° in
[(PhCS2)Au(PPh3)2]38 and 132.04(6)° [(MesCS2)Au-
(PPh3)2].57 The Au−P and Au−S bond lengths of 2 are in
the range of [(PhCS2)Au(PPh3)2]38 and [(MesCS2)Au-
(PPh3)2].57 A secondary interaction of the sulfur atom S2 to
the gold atom with a significant longer Au−S2 2.808(2) Å
distance compared to Au−S1 (2.583(2) Å) is observed. This
interaction is indicated as dotted lines in Figure 1 and Scheme
2. Compound 2 turned out to be, to a certain extent,
solvatochromic. In tetrahydrofuran or chloroform, the solutions
appear either red or violet, originating from a shift of the
maximum of one of its absorption bands from 512 to 531 nm
(Supporting Information Figure S1).
contribution of the JPH coupling.58 The observed chemical
2
shift of the P−CH2−P group is in the range of other dppm
gold(I) compounds, for example, δ = 3.80 ppm in [dppm-
(AuI)2].58 In the 31P{1H} NMR spectrum, a characteristic
singlet was observed at δ = 31.3 ppm, which is in the expected
range. A molecular peak corresponding to the cation of 3 was
detected in the ESI-MS spectrum at m/z = 1423.15 amu
(Supporting Information Figure S2).
Compound 3 crystallized in the monoclinic space group
P21/n with one molecule in the asymmetric unit. Some CH2Cl2
molecules were heavily disordered and removed by using
SQUEEZE.59 The gold(I) atoms are each coordinated by two
phosphorus atoms of two dppm ligands and one sulfur atom of
the ferrocene dithiocarboxylate. This results in a distorted
trigonal planar coordination polyhedron. The angles within this
polyhedron range from 91.82(4)° to 156.46(5)° and thus
significantly deviate from the ideal angle of 120°. As a result of
the complex geometry, the Au atoms are forced into a close
proximity and an Au−Au distance of 2.9461(2) Å is observed.
This distance is in the typical range of aurophilic interactions,
which ranges from about 2.70−3.50 Å.1,60−66 However, because
To study the influence of the phosphine ligand on the
formation of the gold(I) complexes, 1 was treated with
[Au(tht)Cl] in the presence of bis(diphenylphosphino)-
methane (dppm) in a 2:2:1 ratio in CH2Cl2. The digold
4494
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
Scheme 3. Synthesis of 3
of the rigid complex geometry, we cannot clearly prove if there
is an attractive force between the gold atoms. The Au−S bond
lengths (Au1−S1 2.6773(4) Å and Au2−S2 2.6511(13) Å) are,
in contrast to compound 2, almost equivalent showing a
heteroallylic arrangement of the ferrocene dithiocarboxylate
ligand. The other bond parameters are within the expected
range. The gold(I) atoms are within the bridgehead of a
bimetallabicyclo[3.3.3]undecane structure. This kind of struc-
tural motif is rare in gold chemistry. It has not been previously
observed for dithiocarboxylate ligands but it has been reported
for dithiophosphonates, for example, in bis(μ2-(4-methoxy-
phenyl)-O-(cyclopentyldithiophosphonato)-digold(I).67 It is
worth noticing that in the closely related compound
[(PhCSS)Au2(dppm2)]Cl, in contrast to 3, the dithiocarbox-
ylato moiety coordinates as a monodentate ligand to only one
of the gold atoms.68
conducting salt, we assume that the irreversible oxidation steps
are located on the dithiocarboxylate moiety. Note: compounds
2 and 3 exhibit further quasi-reversible oxidation waves
centered at E01/2 = 0.22 V and E10/2 = 0.52 V for 2 and E01/2
=
0.21 V for 3 respectively (see Supporting Information Figures
S4 and S5). However, the origin of these redox processes
remains unassigned, as this is under currently investigation.
By treating the mixture of 1 and [Au(tht)Cl] with
bis(diphenylphosphino)ferrocene (dppf), the polymeric prod-
uct [(FcCSS)Au(dppf)]n (4) was obtained (Scheme 4).
Complex 4 could not be dissolved in common organic solvents
without decomposition. Thus, a characterization by NMR was
not possible. Single crystals of 4 were obtained by overlaying a
solution of 1 and dppf in dichloromethane with a solution of
[Au(tht)Cl] in a mixture of dichloromethane and THF. Red
crystals were grown at the phase border.
Compound 4 crystallized as two different polymorphs. One
polymorph crystallized in the monoclinic space group P21/c
with four molecules in the unit cell. An X-ray powder
diffraction experiment performed with microcrystalline powder
of this sample showed good agreement with the calculated
powder pattern (Mercury 3.148 was used for the calculation;
Supporting Information Figure S6). The other polymorph
crystallized in the monoclinic space group P21/n with
additional solvent molecules (CH2Cl2) in the unit cell.
Although the ferrocenyl units are orientated slightly differently
in both polymorphs, the structural scaffold is the same. Because
of disorder problems the X-ray data collected from both
polymorphs of 4 were poor but the connectivity of 4 and its
composition were deduced. However, further bonding
parameters cannot be discussed. The gold atoms are
coordinated by two phosphorus and two sulfur atoms, resulting
in a coordination number of four. In contrast to 2 the Au−S
bond lengths in 4 are almost equivalent. A distorted
tetrahedron is formed around the gold atoms. Four-coordinate
gold(I) compounds are rare. They are mostly observed in the
presence of aromatic sulfur containing ligands, such as
dithiocarboxylates,34,38,57 some phosphines,38,57,70 and phos-
phines with tethered thio groups.71 As a result of the
coordination of the flexible and bidentate dppf ligand, an
infinite zigzag chain is formed. To the best of our knowledge no
other similar gold(I) compound have been structurally
Figure 2. Molecular structure of the cation of 3. Hydrogen atoms and
solvent molecules have been omitted for clarity. Selected bond lengths
(Å) and angles (deg): Au1−Au2 2.9461(2), Au1−S1 2.6773(4), Au1−
P1 2.3309(11), Au1−P2 2.3007(12), Au2−S2 2.6511(13), Au2−P3
2.3104(12), Au2−P4 2.3408(12) C11−S1 1.693(5), C11−S2
1.708(5); P2−Au1−Au2 93.28(3), P2−Au1−S1 111.67(4), P2−
Au1−P1 156.46(5), P1−Au1−Au2 88.93(3), P1−Au1−S1 91.82(4)
P3−Au2−Au1 93.05(3), P3−Au2−S2 110.38(4), P3−Au2−P4
156.01(4), P4−Au2−Au1 88.69(3), P4−Au2−S2 93.60(4), S1−
Au1−Au2 87.84(3), S2−Au2−Au1 87.46(3), S1−C11−S2 125.5(3).
Compounds 1−3 were investigated by cyclic voltammetry
measurements (Supporting Information Figures S3−S5). All
measurements were performed in THF at room temperature.
Potentials are quoted relative to the ferrocene/ferrocenium
couple (Fc/Fc+) as the internal standard. For each compound
characterized before, but a few examples of polymeric gold(I)
72,73
complexes are known, for example, [(dppf)AuCl]n
and
74
[(MandyPhos)AuCl]n (MandyPhos =2,2′-bis(N,N-dimethy-
lamino phenyl methyl)-1,1′-bis(diphenylphosphino)-ferrocene)
with trigonal coordination of the gold(I) atom. In 4, we
observed a third coordination mode of the ferrocene
dithiocarboxylate ligand, demonstrating the high variability
coordination modes exhibited by this ligand.
we observed an irreversible oxidation process at about Epa
=
∼0.1−0.2 V. We suggest that this process is caused by an
irreversible oxidation of the dithiocarboxylate function. To
further address this behavior, we applied a different conducting
salt [N(nBu)4][PF]69 (PF− = {Al(OC(CF3)3)4}) to exclude
reactions with the [N(nBu)4][PF6] salt. As there appeared to
be no change in the cyclovoltammograms upon exchanging the
By using bis(diphenylphospino)propane as the phosphine
ligand, the compound [{(FcCSS)Au}2(dppp)] (5) was formed
(Scheme 5). It was isolated by crystallization from pentane/
4495
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
Scheme 4. Synthesis of 4
Compound 5 crystallized in the monoclinic space group
P21/c with one molecule in the asymmetric unit and an
additional equivalent of the solvent molecule (Figure 4). The
Figure 3. Shown is a section of the coordination polymer 4. Hydrogen
atoms and solvent molecules have been omitted for clarity.
CH2Cl2 in low yield. In contrast to 2−4, the gold atoms of 5
show the common coordination number of two. Folding of the
n-propyl chain could prevent the formation complexes with
higher coordination numbers. However, the ferrocene
dithiocarboxylate ligand coordinates again in a new fashion.
Figure 4. Molecular structure of 5. Hydrogen atoms and solvent
molecules have been omitted for clarity. Selected bond lengths (Å)
and angles (deg): Au1−Au2 3.1063(5), Au1−P1 2.2676(4), Au2−P2
2.2608(6), Au1−S1 2.3260(5), Au2−S3 2.3126(6), C11−S1
1.7255(6), C11−S2 1.6604(4), C22−S3 1.7238(3), P1−Au1−S1
176.283(13), P2−Au2−S3 175.945(13), P1−Au1−Au2 92.411(8)
P2−Au2−Au1 92.533(8), S1−Au1−Au2 91.281(9), S3−Au2−Au1
87.539(9), S1−C11−S2 124.59(2), S3−C22−S4 122.45(2).
1
In the H NMR spectrum, the expected set of signals was
detected. Compared with the free ligand the signals of
phosphorus adjacent protons in the bridging dppp ligand are
shifted by about 0.8 ppm to lower field, those in the middle
position are shifted about 0.2 ppm. The 31P{1H} signal was
detected at δ = 27.5 ppm. In the 13C{1H} NMR spectrum the
signal for carbon atoms adjacent to the phosphorus are split
into a doublet of doublets at δ = 28.2 ppm through coupling
gold atoms are now coordinated in the common linear manner,
with the P−Au−S angles (176°) being nearly identical for both
atoms. The gold−sulfur distances of the coordinating sulfur
atoms are Au1−S1 2.3260(5) Å and Au2−S3 2.3126(6) Å,
whereas the distances to the noncoordinating sulfur atoms (S2
and S4) are longer than 3.3 Å. In general, 5 shows some
similarities with the related complex [(dppp)(AuCl)2].75 The
Au−Au separation in 5 is 3.1063(5) Å, which is significantly
with both phosphorus atoms. The coupling constants are 1JPC
=
3
34.2 Hz and JPC = 10.2 Hz. The carbon atom in the center of
the dppp bridge shows a poorly shaped triplet at δ = 19.7 ppm,
2
due to a small JPC = 2.5 Hz coupling. This interpretation was
confirmed by a 13C{1H, 31P} NMR experiment in which each
signal is observed as a singlet (Supporting Information Figures
S7−S10).
Scheme 5. Synthesis of 5
4496
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
shorter than in its chloro analogue (3.2368(9) Å). The P−Au
bond lenghts in 5 (Au1−P1 2.2676(4) Å and Au2−P2
2.2608(6) Å) are only slightly different to the chloro complex
(Au1−P1 2.237(3) Å and Au2−P2 2.244(3) Å). For
[(dppp)(AuCl)2], an additional isomer has been reported in
the literature, in which there are intermolecular Au−Au
contacts but no intramolecular ones. As a result of these
contacts a linear polymeric structure is formed.76 In our
experiments no related isomer was observed.
Attempts to extend the rich coordination chemistry of the
ferrocene dithiocarboxylate ligand to other coinage metals were
only partly successful. One copper complex was obtained but
attempts to make a silver complex were unsuccessful. In a
comparable procedure to the synthesis of 2, [(Ph3P)3CuCl]
was reacted with 1 in CH2Cl2 to give [(FcCSS)Cu(PPh3)2] (6)
in good yield. The product was fully characterized by standard
analytical/spectroscopic techniques and the solid state-structure
was established by single-crystal X-ray diffraction. Compound 6
is comparable to the analogous gold compound 2. The NMR
spectra show the expected set of signals. The signals of the
Figure 5. Molecular structure of 6. Hydrogen atoms and solvent
molecules have been omitted for clarity. Selected bond lengths (Å)
and angles (deg): Cu−S1 2.418(2), Cu−S2 2.416(2), Cu−P1
2.250(2), Cu−P2 2.250(2), S1−C11 1.689(5), S2−C11 1.697(5);
P1−Cu−P2 125.22(6), S1−Cu−S2 74.41(5), P1−Cu−S1 108.35(6),
P1−Cu−S2 113.42(6), P2−Cu−S1 115.43(6), P2−Cu−S2 108.87(6),
S1−C11−S2 119.3(3).
1
ferrocenyl unit show characteristic signals in the H NMR
spectrum. For the unsubstituted ring, a singlet is seen at δ =
4.13 ppm, whereas the signals of the other ring are observed as
mulitplets at δ = 5.49 and 4.22 ppm. In the 31P{1H} NMR, the
expected signal is seen at δ = −0.8 ppm, which is close to
[(PPh3)2CuCl] (δ = −3.68 ppm in CDCl3).
Scheme 6. Synthesis of 6
Complex 6 crystallized in the triclinic space group P1. In
̅
contrast to the gold(I) compound 2, the tetrahedral
coordination observed in 6 is very common in copper
chemistry. Although the structure of 2 and 6 appear similar
at a first glance, there are some significant differences. In
contrast to 2, the ferrocene dithiocarboxylate ligand in 6
coordinates almost symmetrically to the copper atom (Cu−S1
2.418(2) Å and Cu−S2 2.416(2) Å) in a chelating mode. This
results in a significantly larger bite angle of 74.41(5)°
(66.13(6)° in 2) and a smaller P1−Cu−P2 angle
(125.22(6)°). The Cu−P bond lengths are in the expected
range. As a result of the similar S−C11 bond lengths (S1−C11
1.689(5) Å, S2−C11 1.697(5) Å) the ferrocene dithiocarbox-
ylate ligand coordinates in a hetero allylic-mode.
Figure 6. 57Fe−Mossbauer spectra obtained at T = 77 K of 2 (a), 3
̈
(b), and 4 (c). The solid lines represent the result of a best fit analysis
using Lorentzian line shape. The so obtained Mossbauer values are for
̈
2 and 3 are Isomer shift δ = 0.51 0.03 mms−1; quadrupole splitting
ΔEQ = 2.21 0.03 mms−1 and line width Γ = 0.40 0.03 mms−1 (a
and b). Complex 4 exhibits δ = 0.50 0.03 mms−1, ΔEQ = 2.26 0.03
mms−1, and Γ = 0.34 0.03 mms−1 (c).78
CONCLUSION
■
We have introduced the ferrocene dithiocarboxylate ligand into
the chemistry of gold(I) and copper(I) and the first structurally
characterized complexes are reported. Surprisingly, the
ferrocene dithiocarboxylate ligand shows very flexible coordi-
nation behavior, which allowed for the formation of different
coordination polyhedra, although the coordinating ligand atoms
were the same in each case. None of the compounds reported
herein exhibit coordination by solvent molecules. In the four
different gold(I) complexes four different coordination modes
of the ligand are seen. In only one example (compound 5), the
expected linear coordination environment of the gold(I) atoms
was observed. In all other compounds, coordination polyhedra
with high-coordinate gold(I) atoms were formed. Although
high-coordinate gold(I) compounds with other dithiocarbox-
ylate ligands are known, the high variability in the coordination
To check the valence state of the iron centers in compounds
2, 3, and 4, 57Fe−Mossbauer spectroscopy was performed.
̈
Figure 6 shows that all three compounds exhibit one doublet in
their Mossbauer spectra obtained at T = 77 K. All three
̈
compounds exhibit isomer shifts (δ = 0.51 0.03 mms−1) and
quadrupole splittings (ΔEQ = 2.21 0.03 mms−1 for 2 and 3
and ΔEQ = 2.26 mms−1 0.03 mms−1 for 4), which are the
same within the experimental error. These values are typical for
diamagnetic ferrocenes.77 The Mossbauer spectrum of 2
̈
obtained at T = 5 K and an external field of B = 5 T
(Supporting Information Figure S11) shows a magnetic
splitting which is only due to the external field, which confirms
the diamagnetic ground state of the ferrocene centers in 2, 3,
and 4.
4497
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
(21) Fierro-Gonzalez, J. C.; Gates, B. C. Chem. Soc. Rev. 2008, 37,
2127.
(22) Carrettin, S.; Blanco, M. C.; Corma, A.; Hashmi, A. S. K. Adv.
Synth. Catal. 2006, 348, 1283.
(23) Hashmi, A. S. K.; Hutchings, G. J. Angew. Chem., Int. Ed. 2006,
45, 7896.
(24) Hashmi, A. S. K.; Rudolph, M. Chem. Soc. Rev. 2008, 37, 1766.
(25) Hashmi, A. S. K. Nachr. Chem. 2009, 57, 379.
(26) Marion, N.; Nolan, S. P. Chem. Soc. Rev. 2008, 37, 1776.
(27) Schmidbaur, H.; Schier, A. Z. Naturforsch., B: J. Chem. Sci. 2011,
66, 329.
(28) Pearson, R. G. Inorg. Chim. Acta 1995, 240, 93.
(29) Hogarth, G. In Progress in Inorganic Chemistry; John Wiley &
Sons, Inc.: Hoboken, NJ, 2005; p 71.
(30) Arias, J.; Bardají, M.; Espinet, P. Inorg. Chem. 2008, 47, 1597.
(31) Khan, M. N. I.; King, C.; Heinrich, D. D.; Fackler, J. P.; Porter,
L. C. Inorg. Chem. 1989, 28, 2150.
́ ́
(32) Fernandez, E. J.; Lopez-de-Luzuriaga, J. M.; Monge, M.; Olmos,
E.; Gimeno, M. C.; Laguna, A.; Jones, P. G. Inorg. Chem. 1998, 37,
5532.
chemistry of the ferrocene dithiocarboxylate ligand and the
resulting rich structural chemistry is exceptional. We believe
that dithiocarboxylates with other organometallic backbones
may also be suitable as interesting ligands in gold(I) chemistry.
Now that we have a convenient synthesis of 1, we are currently
exploring the coordination chemistry of ferrocene dithiocarbox-
ylate with other metals.
ASSOCIATED CONTENT
■
S
* Supporting Information
Additional figures and crystallographic data in CIF format. This
material is available free of charge via the Internet at http://
pubs.acs.org
AUTHOR INFORMATION
■
Corresponding Author
*E-mail: roesky@kit.edu.
Author Contributions
(33) Assefa, Z.; Staples, R. J.; Fackler, J. P. Inorg. Chem. 1994, 33,
2790.
The manuscript was written with contributions from all
authors. All authors have given their approval to the final
version of the manuscript.
(34) Chiari, B.; Piovesana, O.; Tarantelli, T.; Zanazzi, P. F. Inorg.
Chem. 1985, 24, 366.
(35) Otto, H.; Werner, H. Chem. Ber. 1987, 120, 97.
(36) Naeem, S.; Delaude, L.; White, A. J. P.; Wilton-Ely, J. D. E. T.
Inorg. Chem. 2010, 49, 1784.
(37) Piovesana, O.; Zanazzi, P. F. Angew. Chem., Int. Ed. 1980, 19,
561.
(38) Manotti Lanfredi, A. M.; Ugozzoli, F.; Asaro, F.; Pellizer, G.;
Marsich, N.; Camus, A. Inorg. Chim. Acta 1992, 192, 271.
(39) Oliver, K.; White, A. J. P.; Hogarth, G.; Wilton-Ely, J. D. E. T.
Dalton Trans. 2011, 40, 5852.
Funding
This work was supported by the DFG-funded transregional
collaborative research center SFB/TRR 88 “Cooperative effects
in homo- and hetero-metallic complexes (3MET)” and the
Helmholtz Research School: Energy-Related Catalysis.
Notes
The authors declare no competing financial interest.
(40) Kato, S.; Wakamatsu, M.; Mizuta, M. J. Organomet. Chem. 1974,
78, 405.
(41) Bereman, R. D.; Nalewajek, D. P. J. Inorg. Nucl. Chem. 1981, 43,
519.
(42) Bolzati, C.; Uccelli, L.; Duatti, A.; Venturini, M.; Morin, C.;
Cheradame, S.; Refosco, F.; Ossola, F.; Tisato, F. Inorg. Chem. 1997,
́
36, 3582.
(43) Herberhold, M.; Ott, J.; Haumaier, L. Chem. Ber. 1985, 118,
3143.
REFERENCES
■
(1) Schmidbaur, H.; Schier, A. Chem. Soc. Rev. 2008, 37, 1931.
(2) Gimeno, M. C.; Laguna, A. Chem. Soc. Rev. 2008, 37, 1952.
(3) Jansen, M. Chem. Soc. Rev. 2008, 37, 1826.
(4) Katz, M. J.; Sakai, K.; Leznoff, D. B. Chem. Soc. Rev. 2008, 37,
1884.
(5) Ofir, Y.; Samanta, B.; Rotello, V. M. Chem. Soc. Rev. 2008, 37,
1814.
(6) Puddephatt, R. J. Chem. Soc. Rev. 2008, 37, 2012.
(7) Raubenheimer, H. G.; Cronje, S. Chem. Soc. Rev. 2008, 37, 1998.
(8) Schmid, G. Chem. Soc. Rev. 2008, 37, 1909.
(9) Dehnen, S.; Eichhofer, A.; Corrigan, J. F.; Fenske, D. In
Nanoparticles: From Theory to Application; Schmid, G., Ed.; Wiley-
VCH Verlag GmbH & Co. KGaA: Weinheim, Germany, 2004; p 107.
(10) Dehnen, S.; Eichhofer, A.; Corrigan, J. F.; Fuhr, O.; Fenske, D.
Synthesis and Characterization of Ib-VI Nanoclusters; Wiley-Blackwell:
Hoboken, NJ, 2010.
(11) Grzelczak, M.; Perez-Juste, J.; Mulvaney, P.; Liz-Marzan, L. M.
Chem. Soc. Rev. 2008, 37, 1783.
(12) Hakkinen, H. Chem. Soc. Rev. 2008, 37, 1847.
(13) Laaksonen, T.; Ruiz, V.; Liljeroth, P.; Quinn, B. M. Chem. Soc.
Rev. 2008, 37, 1836.
(14) Myroshnychenko, V.; Rodriguez-Fernandez, J.; Pastoriza-Santos,
I.; Funston, A. M.; Novo, C.; Mulvaney, P.; Liz-Marzan, L. M.; Garcia
de Abajo, F. J. Chem. Soc. Rev. 2008, 37, 1792.
(15) Prasad, B. L. V.; Sorensen, C. M.; Klabunde, K. J. Chem. Soc. Rev.
2008, 37, 1871.
(16) Sperling, R. A.; Rivera Gil, P.; Zhang, F.; Zanella, M.; Parak, W.
J. Chem. Soc. Rev. 2008, 37, 1896.
(17) Wilson, R. Chem. Soc. Rev. 2008, 37, 2028.
(18) Della Pina, C.; Falletta, E.; Prati, L.; Rossi, M. Chem. Soc. Rev.
2008, 37, 2077.
(44) Young, D. J.; Chien, S. W.; Hor, T. S. A. Dalton Trans. 2012, 41,
12655.
(45) Hayashi, T. In Ferrocenes; Wiley-VCH Verlag GmbH:
Weinheim, Germany, 2007; p 105.
̈
(46) Horikoshi, R.; Mochida, T. Eur. J. Inorg. Chem. 2010, 5355.
(47) Deschenaux, R.; Goodby, J. W. In Ferrocenes; Wiley-VCH Verlag
GmbH: Weinheim, Germany, 2007; p 471.
(48) Macrae, C. F.; Bruno, I. J.; Chisholm, J. A.; Edgington, P. R.;
McCabe, P.; Pidcock, E.; Rodriguez-Monge, L.; Taylor, R.; van de
Streek, J.; Wood, P. A. J. Appl. Crystallogr. 2008, 41, 466.
̈
(49) Ahrland, S.; Dreisch, K.; Noren
Phys. 1993, 35, 281.
(50) Haas, A., Helmbrecht, J., Niemann, U., Brauer, G., Ed. Handbuch
́
, B.; Oskarsson, Å. Mater. Chem.
der Praparativen Anorganischen Chemie; Ferdinand Enke Verlag:
̈
Stuttgart, Germany, 1954; Vol. 2, p 1014.
(51) Costa, G.; Reisenhofer, E.; Stefani, L. J. Inorg. Nucl. Chem. 1965,
27, 2581.
(52) Sheldrick, G. M. Acta Crystallogr., Sect. A 2008, 64, 112.
(53) Janoschka, A.; Svenconis, G.; Schunemann, V. J. Phys.: Conf. Ser.
̈
2010, 217, 012005.
(54) Gunnlaugsson, H. P.; Vinda, B. Excel add-on. http://users-phys.
au.dk/hpg/vinda.htm (accessed April 15, 2013).
(55) Trautwein, A. X.; Bill, E.; Bominaar, E. L.; Winkler, H. Struct.
Bonding 1991, 78, 1.
(19) Corma, A.; Garcia, H. Chem. Soc. Rev. 2008, 37, 2096.
(20) Coquet, R.; Howard, K. L.; Willock, D. J. Chem. Soc. Rev. 2008,
37, 2046.
́
(56) Mezailles, N.; Ricard, L.; Gagosz, F. Org. Lett. 2005, 7, 4133.
(57) Davis, D.; Fronczek, F. R.; Schuerman, J. A.; Selbin, J.; Watkins,
S. F. Acta Crystallogr., Sect. E 2006, 62, No. m1524.
4498
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499

Inorganic Chemistry
Article
(58) Schmidbaur, H.; Wohlleben, A.; Wagner, F.; Orama, O.;
Huttner, G. Chem. Ber. 1977, 110, 1748.
(59) Spek, A. J. Appl. Crystallogr. 2003, 36, 7.
(60) Pyykko, P. Angew. Chem., Int. Ed. 2004, 43, 4412.
̈
(61) Schmidbaur, H.; Schier, A. Chem. Soc. Rev. 2012, 41, 370.
(62) Hashmi, A. S. K.; Braun, I.; Nosel, P.; Schadlich, J.; Wieteck, M.;
̈
̈
Rudolph, M.; Rominger, F. Angew. Chem., Int. Ed. 2012, 51, 4456.
(63) Hashmi, A. S. K.; Braun, I.; Rudolph, M.; Rominger, F.
Organometallics 2012, 31, 644.
(64) Hashmi, A. S. K.; Wieteck, M.; Braun, I.; Nosel, P.; Jongbloed,
̈
L.; Rudolph, M.; Rominger, F. Adv. Synth. Catal. 2012, 354, 555.
(65) Hashmi, A. S. K.; Wieteck, M.; Braun, I.; Rudolph, M.;
Rominger, F. Angew. Chem., Int. Ed. 2012, 51, 10633.
(66) Hansmann, M. M.; Rudolph, M.; Rominger, F.; Hashmi, A. S. K.
Angew. Chem., Int. Ed. 2013, 52, 2593.
(67) Maspero, A.; Kani, I.; Mohamed, A. A.; Omary, M. A.; Staples,
R. J.; Fackler, J. P. Inorg. Chem. 2003, 42, 5311.
(68) Wang, J. C.; Liu, L. K. Acta Crystallogr., Sect. C 1994, 50, 704.
(69) Krossing, I.; Raabe, I. Angew. Chem., Int. Ed. 2004, 43, 2066.
(70) Lubbe, G.; Frohlich, R.; Kehr, G.; Erker, G. Inorg. Chim. Acta
̈
̈
2011, 369, 223.
(71) Ortner, K.; Hilditch, L.; Zheng, Y.; Dilworth, J. R.; Abram, U.
Inorg. Chem. 2000, 39, 2801.
(72) Lai-Tee, P.; Hor, T. S. A.; Zhong-Yuan, Z.; Mak, T. C. W. J.
Organomet. Chem. 1994, 469, 253.
(73) Houlton, A.; Mingos, D. M. P.; Murphy, D. M.; Williams, D. J.;
Phang, L.-T.; Hor, T. S. A. J. Chem. Soc., Dalton Trans. 1993, 3629.
(74) Khin, C.; Hashmi, A. S. K.; Rominger, F. Eur. J. Inorg. Chem.
2010, 1063.
(75) Kaim, W.; Dogan, A.; Klein, A.; Zal
2005, 631, 1355.
́ ̌
is, S. Z. Anorg. Allg. Chem.
(76) Cooper, M. K.; Mitchell, L. E.; Henrick, K.; McPartlin, M.;
Scott, A. Inorg. Chim. Acta 1984, 84, L9.
(77) Greenwood, N. N.; Gibb, T. C. Mossbauer Spectroscopy;
̈
Chapman and Hall Ltd.: London, 1971.
(78) Note: Au atoms strongly scatter and absorb 14.4 keV Mossbauer
̈
radiation. Therefore, the statistical quality of the Mossbauer spectra of
̈
2 and 3 presented in Figure 6 is not as high as usually observed for
iron containing coordination compounds due to low count rates. The
Fe concentration in 4 or, more specifically, the concentration of the
resonantly absorbing 57Fe nuclei, which cause the Mossbauer effect
̈
and occurs in 2.1% natural abundance, is about twice as high as in 2
and 3. Therefore, the Mossbauer spectrum obtained for 4 has a better
̈
statistical quality than those of 2 and 3.
4499
dx.doi.org/10.1021/ic500151j | Inorg. Chem. 2014, 53, 4491−4499