New cationic organometallic phosphane ligands and their coordination to gold(I) Dedicated to Professor Heinrich Lang on the occasion of his 60th birthday.

Article abstract of DOI:10.1016/j.jorganchem.2016.02.037

Two novel metallated phosphino ligands [(η⁵-Cp)Fe(η⁶-C₆H₅PPh₂)](PF₆) and [(η⁵-Cp)Fe(η⁶-1,2-C₆H₄(PPh₂)₂)](PF₆) ha

Full text of DOI:10.1016/j.jorganchem.2016.02.037

Accepted Manuscript
New Cationic Organometallic Phosphane Ligands and their Coordination to Gold(I)
Tobias R. Eger, Isabel Munstein, Annika Steiner, Yu Sun, Gereon Niedner-
Schatteburg, Werner R. Thiel
PII:
S0022-328X(16)30070-5
10.1016/j.jorganchem.2016.02.037
JOM 19421
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 22 December 2015
Revised Date: 24 February 2016
Accepted Date: 25 February 2016
Please cite this article as: T.R. Eger, I. Munstein, A. Steiner, Y. Sun, G. Niedner-Schatteburg, W.R.
Thiel, New Cationic Organometallic Phosphane Ligands and their Coordination to Gold(I), Journal of
Organometallic Chemistry (2016), doi: 10.1016/j.jorganchem.2016.02.037.
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ACCEPTED MANUSCRIPT
Cationic arylphosphines bearing a η6-coordinated (η5-Cp)Fe+ moiety were synthesized via a
nucleophilic aromatic substitution reaction. Such ligands open up the access to bimetallic
complexes, and allow studying cooperative effects between the metal sites.
Graphics for contents

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New Cationic Organometallic Phosphane Ligands and their Coordination to
Gold(I)
Tobias R. Eger, Isabel Munstein, Annika Steiner, Yu Sun, Gereon Niedner-Schatteburg,
Werner R. Thiel*
Dedicated to Professor Heinrich Lang on the occasion of his 60th birthday
* Technische Universität Kaiserslautern, Fachbereich Chemie, Erwin-Schrödinger-Straße 54,
D-67663 Kaiserslautern, Germany. E-mail: thiel@chemie.uni-kl.de
Abstract
Two novel metallated phosphino ligands [(η5-Cp)Fe(η6-C6H5PPh2)](PF6) and [(η5-Cp)Fe(η6-
1,2-C6H4(PPh2)2)](PF6) have successfully been synthesized. Therein, the phosphane moieties
are directly bound to the cationic (η5-Cp)Fe fragment. By reaction of [(η5-Cp)Fe(η6-
C6H5PPh2)](PF6) with (thiophene)AuCl, the heterobimetallic complex [(η5-Cp)Fe(η6-
C6H5PPh2(AuCl))][PF6] was obtained in good yields. It was characterized spectroscopically as
well as by X-ray structure analysis.
Keywords: Iron, Gold, Phosphine, Solid state structure, Synthesis

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Introduction
Tuning the activity and selectivity of transition metal compounds by slight variations of the
ligand structure is a strategy frequently used in homogeneous catalysis to optimize the
performance of the catalyst. In this context, the substitution of classical aromatic sites in the
ligand backbone against organometallic substituents allows further variations of the steric
and electronic impact of a given ligand system. Since solely stable compounds can be used
for this purpose, ferrocene based systems [1,2], including chiral ones [3,4,5,6,7], became the
most prominent representatives for this strategy during the last two decades. Furthermore,
ferrocene chemistry is closely related to well-established arene chemistry allowing to
introduce a broad variety of substituents into the ligand backbone. Even the effects of a
reversible switching between the FeII and the FeIII redox states on the properties of a series
of transition metal catalysts have been investigated [8,9,10,11].
In contrast to the well-known chemistry of ferrocene-based ligands in transition metal
chemistry, the coordinative behavior of ligands bearing a [(η5-Cp)Fe(η6-arene)]+ fragment
instead of the ferrocenyl moiety is much less established. The starting materials for the
synthesis of such systems have been known for long, since the first [(η5-Cp)Fe(η6-arene)]+(X-)
compounds have already been reported in the 1960ies [12,13]. Due to the electron-
withdrawing feature of the [(η5-Cp)Fe]+ fragment, the η6-coordinated arene site becomes
accessible towards nucleophilic aromatic substitution reactions [14,15,16,17]. For applying
this type of reactivity to obtain more complex systems, a chloro arene ligand has to be
-
introduced, as it is the case for compounds such as [(η5-Cp)Fe(η6-C6H5Cl)]+(PF6 ) and ortho-,
-
meta-, resp. para-substituted [(η5-Cp)Fe(η6-C6H4Cl2)]+(PF6 ). These compounds can be
synthesized from a mixture of ferrocene, AlCl3 and the corresponding chloro benzene in
quite reasonable yields [13]. We recently were able to prove this concept by synthesizing the
cationic N,N’-chelating ligand [(η5-Cp)Fe(η6-C6H5NHCH2CH2NH2)]+. This compound can e.g. be
coordinated in a chelating manner to palladium dichloride giving the first transition metal
complex bearing a [(η5-Cp)Fe(η6-arene)]+ based donor site [18]. Furthermore, the palladium
complex shows an unexpected fragmentation behavior under CID ESI-MS conditions by
splitting FeCl2, being in the electronic quintet state .
In 1995, Roberts et al. described the synthesis of [(η5-Cp)Fe(η6-arene)]+ cations by reacting
ferrocene, aluminum chloride and aluminum with a variety of arenes under microwave

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conditions [19]. By applying this method on triphenyl phosphine, they were able to obtain
mixtures of the mono-cationic compound [(η5-Cp)Fe(η6-C6H5PPh2)](PF6) and the di-cationic
species [((η5-Cp)Fe(η6-C6H5))2PPh][PF6]2 with medium to good yields. However, the authors
gave no description on the separation of these mixtures and there is no hint in the literature
that these compounds have ever been used for coordination to transition metal sites. In
2008 Danjo et al. reported the synthesis of a series of (tricarbonyl)chromium compounds
containing η6-coordinating arylphosphine ligands by introducing the phosphine site using
BH3 protected lithium phosphides [20]. They took the fluorine substituted derivatives
[Cr(CO)3(η6-C6H6-xFx)] (x = 1,2) as the starting materials, since fluoro substituents are well-
known to be perfect leaving groups in nucleophilic aromatic substitution reactions. Aubert,
Fensterbank, and H. Amouri could obtain [(η5-Cp)Ru(η6-C6H5PPh2)](OTf) (OTf = triflate) by
nucleophilic aromatic substitution of the chloro substituent in [(η5-Cp*)Ru(η6-C6H5Cl)](OTf)
against a diphenylphosphino substituent [21,22,23]. The corresponding complex with AuCl
coordinated to the phosphine site catalyzes the cyclisation of β-hydroxyallenynes with much
higher activity than its counterpart (PPh3)AuCl. This clearly speaks for a collaborative
interaction between the gold site and the [(η5-Cp)Ru(η6-arene)]+ cation. It should be
mentioned at this point, that Salzer et al. have published cationic phosphine ligands based
on the cobaltocinium structure by using Li(C5H4-PPh2) as the transfer reagent [24].
We here report the first access to triaryl phosphane ligands bearing a (η5-Cp)Fe+ fragment
being η6-coordinated to one of the aryl moieties by applying a nucleophilic aromatic
substitution reaction. Furthermore, the first transition metal complex of such a type of
ligand could be obtained by coordinating the phosphorus donor site to gold(I).
Results and discussion
Treatment of ferrocene with chlorobenzene or 1,2-dichlorobenzene in the presence of
aluminum chloride according to a published procedure gave the halogenated cationic η5-
cyclopentadienyliron(II)arene complexes 1a and 1b in good yields (Scheme 1) [13]. These
intermediates were converted into the cationic organometallic phosphine ligands 2a and 2b
by means of a nucleophilic aromatic substitution reaction with lithium diphenylphosphide
(LiPPh2) in THF. Lithium diphenylphosphide was freshly prepared from freshly distillated
diphenylphosphine and butyllithium. Alternatively, a commercially available solution of

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potassium diphenylphosphide (KPPh2, 0.5 M in THF) can be applied, giving slightly lower
yields. 1a was obtained from one equivalent of LiPPh2, [(η5-Cp)Fe(ƞ6-C6H5PPh2)](PF6) (2a)
after 12 h of reaction as an orange microcrystalline solid in 71% yield.
Scheme 1. Synthesis of the cyclopentadienyl iron(II) arene complexes 1a,b and 2a,b.
1
The H NMR spectrum recorded from a solution of 2a in aceton-d6 proved the synthesis of
the compound (for spectra see the Supporting Information): A singlet 5.23 ppm can be
assigned to the protons of the cyclopentadienyl ring. It is found shifted slightly to higher field
compared to compound 1a. The resonances of the protons in the meta- and the para-
position of the η6-coordinating arene ring are observed as two triplets at 6.21 and 6.57 ppm.
A doublet at 6.60 ppm can be assigned to the protons in the ortho-position of this ring,
which implies a quite small coupling of these two protons to the phosphorous atom in the
close neighborhood. The resonances of the other aromatic protons of the
diphenylphosphinyl moiety are identified as a multiplet at around 7.52 ppm. Aside to the
typical septet resonance of the hexafluorophosphate anion, there is a singlet at -5.9 ppm in
the 31P NMR spectrum of 2a which is assigned to the central phosphorus atom of the cation
[(η5-Cp)Fe(ƞ6-C6H5PPh2)]+. This chemical shift is quite typical for triaryl phosphines. It is only
slightly deshielded compared to triphenylphosphine [25] and in good agreement with the
data published by Roberts et al. for a mixture of 2a and the dicationic species [((η5-Cp)Fe(η6-
C6H5))2PPh](PF6)2 [19]. There is no hint for the formation of a phosphine oxide in the 31P
NMR spectrum. ESI mass spectrometry further confirms the synthesis of 2a: a molecular
mass of m/z = 383.1 amu (calcd: 383.1) was found. The infrared spectrum of 2a mainly
shows weak aromatic C-H stretching vibrations (3121, 2963, 2874 cm-1) and a very strong
peak for the hexafluorophosphate anion at 827 cm-1.
By gas diffusion of diethyl ether into a saturated solution of 2a in dichloromethane, crystals
being suitable for a single-crystal X-ray analysis could be obtained. Compound 2a crystallizes

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in the monoclinic space group P21/c with four cations and four hexafluorophosphate anions
in the unit cell. Figure 1 shows the structure of 2a in the solid state.
Figure 1. Molecular structure of 2a in the solid state; characteristic bond lengths [Å] and
bond angles [°]: Fe1-C1 2.052(4), Fe1-C2 2.055(3), Fe1-C3 2.053(4), Fe1-C4 2.060(3), Fe1-C5
2.055(3), Fe1-C6 2.068(3), Fe1-C7 2.078(3), Fe1-C8 2.091(3), Fe1-C9 2.083(3), Fe1-C10
2.082(3), Fe1-C11 2.104(3), P1-C11 1.847(3), P1-C12 1.826(3), P1-C18 1.840(3), P2-F4
1.596(2), P2-F5 1.562(3), P2-F6 1.609(2), P2-F2 1.586(2), P2-F3 1.580(2), P2-F1 1.605(3), C11-
P1-C12 100.75(13), C11-P1-C18 100.76(14), C12-P1-C18 103.73(14).
Compound 2a adopts the structure of a typical sandwich-type complex. The two planes of
the five- and the six-membered ring are oriented almost parallel to each other ( : 0.61°).
The distances between the iron site and the carbon atoms of the coordinating aromatic
moieties are typical for [(η5-Cp)Fe(η6-arene)]+ derivatives. Among all distances between the
iron site and the carbon atoms of the six- membered ring, the distance Fe1-C11 is clearly the
longest, implying a slight steric or electronic perturbation in this position caused by the
neighboring phosphorus atom. This is confirmed by a bending of the C11-P1 bond towards

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the iron center by approx. 10° with respect to the plane of the six-membered ring. The
lengths of the P-C bonds are comparable to the values observed for diphenylphosphino
ferrocene (1.843 Å, 1.840 Å, 1.810 Å) [26]. The same is true for the C-P-C angles which are
smaller than the ideal tetrahedral angle (mean values: 2a, 101.74°; diphenylphosphino
ferrocene, 101.1° [26], [(η5-Cp*)Ru(η6-C6H5PPh2)AuCl, 105.02° [21]). Therefore, sum of the C-
P-C angles in 2a (305.23°) is also smaller than the sum of the C-P-C angles in triphenyl
phosphine (308.57°) which can be explained by the presence of the electron-withdrawing
[(η5-Cp)Fe]+ fragment [27].
Treatment of the compound [(η5-Cp)Fe(η6-1,2-C6H4Cl2)](PF6) (1b) with two equivalents of
lithium diphenylphosphide in THF resulted in the formation of [(η5-Cp)Fe(ƞ6-1,2-
C6H4(PPh2)2](PF6) (2b) as a reddish brown microcrystalline solid in 42% yield (Scheme 1). The
1H NMR spectrum recorded from a solution of 2b in acetonitrile-d3 proved the presence of a
pure compound. A singlet at 5.16 ppm can be assigned to the resonances of the
cyclopentadienyl protons. It is found at almost the same chemical shift as the Cp resonance
of 2a. Two multiplets at 6.30 and 6.75 ppm are due to the presence of the four protons of
the η6-coordinating six-membered ring. A set of multiplets at around 7.38 ppm can be
assigned to the protons of the phenyl moieties not coordinating to the iron site. In the 31P
NMR spectrum of 2b, there is a resonance at -144.6 ppm (hexafluorophosphate) and only
one further signal at 9.41 ppm. The presence of solely one signal for the two phosphorus
centers in 2b speaks for either a rapid rotation (with respect to the NMR time-scale) around
the P-C bonds connecting the phosphorus atoms and the central η6-1,2-C6H4 unit, or the
presence of one symmetric and frozen rotamer. In comparison to 2a the resonance at 9.41
ppm is strongly shifted towards lower field! The same is true for comparison of this value
with the data of free 1,2-bis(diphenylphosphino)benzene (δ = -14.3 ppm) [28]. This speaks
for a pronounced deshielding of the phosphorus centers in compound 2b. Since 1,2-
bis(diphenylphosphino)benzene is well-known to form stable chelating and binuclear
complexes with a whole series of transition metal fragments, the successful synthesis of 2a
shall open up an access to a broad range of novel heterobi- and -trimetallic complexes.
To synthesize the heterobimetallic iron(II)-gold(I) complex 3, the cationic phosphine ligand
2a was reacted in dichlormethane with one equivalent of tetrahydrothiophene gold(I)

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chloride. The reaction, which was performed under exclusion of light, was finished in
between 30 min. After work-up, 2a was obtained as a yellow solid in yields of 71%.
Scheme 2. Synthesis of the iron(II)-gold(I) complex 3.
ESI mass spectrometry (m/z = 614.9; calcd.: 615.0) as well as elemental analysis confirm the
1
synthesis of [(η5-Cp)Fe(ƞ6-C6H5PPh2(AuCl))](PF6) (3). In the H NMR spectrum, there is a
singlet at 4.95 ppm, being assigned to the resonance of the η5-Cp protons. This resonance is
slightly shifted to higher field compared to the data of 2a, which can be interpreted as the
result of an enhanced steric shielding of these protons due to the presence of the AuCl
moiety. The resonances of the coordinating six-membered ring are found in the region
between 6.25 and 6.40 ppm, those of the two non-coordinating phenyl rings are observed at
7.49 to7.70 ppm. The coordination of the phosphorus atom to the gold(I) site is most clearly
visible in the 31P NMR spectrum: The according resonance appears as a singlet at 32.2 ppm,
thus as expected strongly shifted to lower field compared to 2a due to the coordination of
the gold(I) center. The resonance of the analogue ruthenium complex [(η5-Cp)Ru(ƞ6-
C6H5PPh2(AuCl))](PF6) was observed at 35.6 ppm as documented in the literature [21].
By slow diffusion of diethyl ether into a saturated solution of 3 in dichloromethane, yellow
crystals suitable for a single crystal X-ray structure analysis could be obtained. The
heterobimetallic complex 3 crystallizes as a dimer in the monoclinic space group P21. Figure
2 shows the structure of the cation 3 in the solid state and Figure 3 shows its dimeric
structure.

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Figure 2. Molecular structure of one of the two crystallographically independent cations of
compound 3 in the solid state; characteristic bond lengths [Å], bond angles [°], and dihedral
angles [°].The bond parameters for the second cation are almost identical: Au1-Cl1 2.282(2),
Au1-P1 2.227(2), Fe1-C1 2.072(9), Fe1-C2 2.061(10), Fe1-C3 2.078(12), Fe1-C4 2.056(14),
Fe1-C5 2.041(14), Fe1-C6 2.064(12), Fe1-C19 1.996(13), Fe1-C20 2.032(15), Fe1-C21
2.045(12), Fe1-C22 2.029(14), Fe1-C23 2.033(15), P1-C1 1.827(8), P1-C7 1.814(8), P1-C13
1.804(8), Cl1-Au1-P1 170.59(7), Au1-P1-C1 109.9(3), Au1-P1-C7 119.0(3), Au1-P1-C13
112.0(3), Au1-P1-C1-C2 45.4(8).

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Figure 3. Molecular structure of the Au-Au bound dimer of compound 3 in the solid state;
characteristic bond lengths [Å] and dihedral angles [°]: Au1-Au2 3.179(6), Cl1-Au1-Au2-Cl2
107.93(7), P1-Au1-Au2-P2 113.48(7), Cl1-Au1-Au2-P2 69.21(7), Cl2-Au2-Au1-P1 69.38(8).
In the dimeric structure, two cationic subunits are connected via a typical gold(I)-gold(I) (d10-
d10) interaction [29,30,31]. The bond length (dAuAu: 3.179 Å) is shorter than the sum of the
van-der-Waals radii of gold(I) (3.32 Å). The Au-Cl vectors of the two subunits are opening up
a dihedral angle (Cl1-Au1-Au2-Cl2) of 107.9°. The structural parameters of both subunits are
almost identical: In contrast to chlorido(triphenylphosphine)gold(I), which comprises an
almost linear P-Au-Cl arrangement [32], P-Au-Cl angles of 170.9° and 170.6° are found for 3.
This is not due to a steric repulsion between the P-Au-Cl fragment and the (η6-Cp)Fe(η6-
C6H5) site, since the bending of the P-Au-Cl angle brings this fragment closer to the iron
center. In contrast there might be a weak attraction between the cationic center and the
electron rich gold(I) ion or weak hydrogen bonds between the chlorido ligand and the
protons of the neighboring cyclopentadienyl protons. The P-Au distances (2.238(2) and
2.227(2) Å) are close to the value found for chlorido(triphenylphosphine)gold(I) [33]. The
distances between the iron(II) center and the carbon atoms of the coordinating six-
membered ring are in sum shorter than those found for the precursor compound (2a).

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Conclusion
We were able to show, that nucleophilic aromatic substitution opens up an efficient route
for the synthesis of triaryl phosphine ligands containing the η5-CpFe+ fragment being
coordinated to one of the phosphine’s aryl units. Hereby mono- as well as diphosphine
ligands can be obtained. By coordination of the AuCl fragment, the first transition metal
complex of such a cationic phosphine could be obtained. In the near future, other transition
metal containing fragments will be reacted with the novel phosphine ligands described
herein. The electronic impact of the cationic aryl substituent on spectroscopic features as
well as on the reactivity of the desired multimetallic complexes will be investigated.
Experimental section
General Remarks: All reactions were carried out under an argon atmosphere using Schlenk
techniques. The solvents were dried and degassed before use according to standard
techniques. Other reagents were obtained from commercial suppliers and used as received.
1H, 13C and 31P NMR spectra were recorded on BRUKER Spectrospin Avance 200, 400 and 600
spectrometers. The chemical shifts are referenced to internal solvent resonances. Infra-red
spectra were recorded on a Perkin Elmer FT-ATR-IR spectrometer Spectrum 100 equipped
with a diamond coated ZnSe window. ESI-mass measurements were performed on a BRUKER
Esquire 6000plus device by introducing solutions of the compounds in acetonitrile.
Elemental analyses were carried out with a vario MICRO cube elemental analyzer at the
Analytical Department of the Technische Universität Kaiserslautern. Compounds 1a and 1b
were obtained according to procedures published in the literature [13]. The NMR spectra of
the iron complexes generally show slightly broadened resonances. This might be due to
some paramagnetic impurities and hinders the assignment of P,C-coupling constants.
(η6-Diphenylphosphinobenzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate (2a):
0.8 mL (688 mg, 2.00 mmol) of n-butyllithium were added drop-wise to a solution of 250 mg
(1.34 mmol) of diphenylphosphine in 10 mL of diethyl ether kept at -30 °C. The reaction
mixture was stirred for 4 h while slowly warming up to room temperature. The solvent was
removed under vacuum and the crude product was washed two times with 15 mL of n-
pentane. The resulting yellow solid was dissolved in 20 mL of THF. 521 mg (1.38 mmol) of η6-

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chlorobenzene-η5-cyclopentadienyliron(II) hexafluorophosphate (1a) were added and the
solution was stirred for further 18 h. The solvent was removed under vacuum and the crude
product was redissolved in 20 mL of dichloromethane. The organic solution was filtered, the
solvent was removed under vacuum and the crude product was washed two times with 15
mL of diethyl ether. Crystallization from dichloromethane/diethyl ether gave orange crystals.
Yield: 502 mg (0.94 mmol, 71%). Elemental analysis calcd. for C23H20F6FeP2: C 52.30, H 3.82,
found: C 51.98, H 3.77%. 1H NMR (600.13 MHz, acetone-d6): δ 7.53−7.51 (m, 10 H, HPh), 6.60
(d, 3JHH = 4.3 Hz, 2 H, H-2), 6.57 (t, 3JHH = 6.0 Hz, 1 H, H-4), 6.21 (t, 3JHH = 5.4 Hz, 2 H, H-3), 5.23
(s, 5 H, HCp) ppm. 13C{1H} NMR (150.92 MHz, acetone-d6): δ 135.2 (C-9), 135.0 (C-10), 131.3
(C-7), 130.2 (C-8), 103.0 (C-1), 91.2 (C-3), 89.4 (C-2), 88.8 (s, C-4), 78.6 (CCp) ppm. 31P{1H}
1
-
NMR (242.94 MHz, acetone-d6): δ -5.9 (s), -144.2 (sept, JPF = 707.9 Hz, PF6 ) ppm. 19F{1H}
1
-
NMR (376.46 MHz, acetone-d6): δ -72.5 (d, JPF = 707.7 Hz, PF6 ) ppm. ESI MS (acetonitrile):
m/z = 383.1 [CpFeC6H5PPh2]+. IR (ATR): ν = 3121w, 2963w, 2874w, 1588w, 1572w, 1506w,
1479w, 1436m, 1421m, 1403w, 1318w, 1287w, 1160w, 1122w, 1097w cm-1.
(η6-1,2-Bis(diphenylphosphino)benzene)(η5-cyclopentadienyl)iron(II) hexafluorophosphate
(2b): 1.6 mL (1.38 mg, 4.00 mmol) of n-butyllithium were added drop-wise to a solution of
500 mg (2.68 mmol) of diphenylphosphine in 10 mL of diethyl ether at -30 °C. The reaction
mixture was stirred for 4 h while slowly warming up to room temperature. The solvent was
removed under vacuum and the crude product was washed twice with 15 mL of n-pentane.
The obtained yellow solid was dissolved in 20 mL of THF. 553 mg (1.34 mmol) of η6-1,2-
dichlorobenzene-η5-cyclopentadienyliron(II) hexafluorophosphate were added and the
solution was stirred for further 18 h, while the color of the solution turned from green to
dark red. The solvent was removed under vacuum and the crude product was redissolved in
20 mL of dichloromethane. The organic solution was filtered and the solvent was removed
under vacuum. The crude product was washed twice with 15 mL of diethyl ether yielding 400
mg (0.56 mmol, 42%) of a reddish brown solid. Elemental analysis calcd. for C35H29F6FeP3: C
1
59.01, H 4.10, found: C 59.31, H 4.21%. H NMR (400 MHz, acetonitrile-d3): δ 7.30-7.45 (m,
20 H, HPh), 6.75 (m, 2 H, H-4), 6.30 (m, 2 H, H-3), 5.16 (s, 5 H, HCp) ppm. 13C{1H} NMR (101
MHz, acetonitrile-d3): δ 134.4 (C-9), 130.9 (C-10), 129.2 (C-7), 127.7 (C-8), 107.8 (C-1), 89.7
(C-4), 88.6 (C-3), 82.1 (HCp) ppm. 31P{1H} NMR (162 MHz, acetonitrile-d3): δ 9.41 (s), -144.6

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1
1
-
(sept, JPF = 706.2 Hz, PF6 ) ppm. 19F{1H} NMR (376 MHz, acetonitrile-d3): δ -72.9 (d, JPF =
-
707.7 Hz, PF6 ) ppm. ESI MS (acetonitrile): m/z = 567.1 [CpFeC6H4-(PPh2)2]+.
(η6-Diphenylphosphinobenzene)(η5-cyclopentadienyl)iron(II)gold(I)chloride
hexafluorophosphate (3): 112 mg (0.36 mmol) of chloro(tetrahydrothiophene)gold(I) were
added to a solution of 173 mg (0.34 mmol) of 1 in 15 mL of dichloromethane. The mixture
was stirred for 30 min at room temperature in the absence of light. The solvent was
removed under vacuum and the crude product was washed twice with 5 mL of diethyl ether.
Crystallization from dichloromethane/diethyl ether gave 176 mg (0.24 mmol, 71%) of
prismatic yellow crystals. Elemental analysis calcd. for C23H20AuClF6FeP2: C 36.32, H 2.65,
found: C 36.22, H 2.44%. 1H NMR (400 MHz, acetonitrile-d3): δ 7.80-7.25 (m, 10 H, HPh), 6.33
(m, 5 H, HAr), 4.95 (s, 5 H, HCp) ppm. 31P{1H} NMR (162 MHz, acetonitrile-d3): δ 32.20 (s), -
1
1
-
144.6 (sept, JPF = 706.2 Hz, PF6 ) ppm. 19F{1H} NMR (376 MHz, acetonitrile-d3): δ -72.9 (d, JPF
= 707.7 Hz, PF6 ) ppm. ESI MS (acetonitrile): m/z = 615.0 [CpFeC6H5-PPh2(AuCl)]+.
-
X-ray structure determinations: Crystal data and refinement parameters are collected in
Table 1. The structures were solved using a direct method (SIR92 [34]), completed by
subsequent difference Fourier syntheses, and refined by full-matrix least-square procedures
[35]. Semi-empirical absorption correction from equivalents (Multiscan) was carried out for
compound 2a, while analytical numeric absorption correction was performed on complex 3
[36]. All non-hydrogen atoms were refined with anisotropic displacement parameters. The
hydrogen atoms were placed in calculated positions and refined using a riding model.

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Table 1. Crystallographic data, data collection and refinement.
2a
3
empirical formula
formula weight
temperature / K
wavelength / Å
crystal system
space group
a /Å
C23H20F6FeP2
528.18
C23H20AuClF6FeP2
760.60
150(2)
150(2)
1.54184
monoclinic
P 21 / c
0.71073
monoclinic
P 21
10.4305(2)
20.9065(4)
10.1661(2)
90
9.2349(2)
24.0489(4)
10.9736(2)
90
b /Å
c /Å
α
β
γ
/°
/°
/°
97.910(2)
90
96.965(2)
90
V /Å3
2195.78(7)
4
2419.13(8)
4
Z
3
2.088
1.598
D
calcd. /Mg/m
-1
6.957
7.438
absorption coefficient /mm
F(000)
1072
1456
2.794 to 32.489
-11<=h<=13
-36<=k<=19
-16<=l<=16
16220
4.23 to 62.64
-11<=h<=11
-16<=k<=24
-10<=l<=11
15075
θ
range for data collection/°
index ranges
reflections collected
Rint
0.0382
0.0308
data/restraints/parameters
goodness-of-fit on F2 a
final Rint [I > 2σ (I)] b
3511/0/289
1.038
10082/121/613
1.023
R1 = 0.0420
wR2 = 0.1156
R1 = 0.0474
wR2 = 0.1176
-
R1 = 0.0381
wR2 = 0.0652
R1 = 0.0459
wR2 = 0.0678
0.004(5)
Rint (all data)
absolute structure parameter
0.822 and -
1.021 and -1.166
-3
largest difference peak and hole/e Å
0.301
a
b
GooF = [Σω(Fo -Fc2)2/(n-p)]1/2; R1 = Σ||Fo|-|Fc||/Σ|Fo|, ωR2 = [Σω(Fo -Fc2)2/ΣωFo2]1/2
2
2

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Acknowledgement
We gratefully thank the DFG-funded transregional collaborative research center SFB/TRR 88
“Cooperative effects in homo- and heterometallic complexes (3MET)” for the financial
support.

ACCEPTED MANUSCRIPT
Scheme, Figure and Table captions
Scheme 1. Synthesis of the cyclopentadienyl iron(II) arene complexes 1a,b and 2a,b.
Figure 1. Molecular structure of 2a in the solid state; characteristic bond lengths [Å] and
bond angles [°]: Fe1-C1 2.052(4), Fe1-C2 2.055(3), Fe1-C3 2.053(4), Fe1-C4 2.060(3), Fe1-C5
2.055(3), Fe1-C6 2.068(3), Fe1-C7 2.078(3), Fe1-C8 2.091(3), Fe1-C9 2.083(3), Fe1-C10
2.082(3), Fe1-C11 2.104(3), P1-C11 1.847(3), P1-C12 1.826(3), P1-C18 1.840(3), P2-F4
1.596(2), P2-F5 1.562(3), P2-F6 1.609(2), P2-F2 1.586(2), P2-F3 1.580(2), P2-F1 1.605(3), C11-
P1-C12 100.75(13), C11-P1-C18 100.76(14), C12-P1-C18 103.73(14).
Scheme 2. Synthesis of the iron(II)-gold(I) complex 3.
Figure 2. Molecular structure of one of the two crystallographically independent cations of
compound 3 in the solid state; characteristic bond lengths [Å], bond angles [°], and dihedral
angles [°].The bond parameters for the second cation are almost identical: Au1-Cl1 2.282(2),
Au1-P1 2.227(2), Fe1-C1 2.072(9), Fe1-C2 2.061(10), Fe1-C3 2.078(12), Fe1-C4 2.056(14),
Fe1-C5 2.041(14), Fe1-C6 2.064(12), Fe1-C19 1.996(13), Fe1-C20 2.032(15), Fe1-C21
2.045(12), Fe1-C22 2.029(14), Fe1-C23 2.033(15), P1-C1 1.827(8), P1-C7 1.814(8), P1-C13
1.804(8), Cl1-Au1-P1 170.59(7), Au1-P1-C1 109.9(3), Au1-P1-C7 119.0(3), Au1-P1-C13
112.0(3), Au1-P1-C1-C2 45.4(8).
Figure 3. Molecular structure of the Au-Au bound dimer of compound 3 in the solid state;
characteristic bond lengths [Å] and dihedral angles [°]: Au1-Au2 3.179(6), Cl1-Au1-Au2-Cl2
107.93(7), P1-Au1-Au2-P2 113.48(7), Cl1-Au1-Au2-P2 69.21(7), Cl2-Au2-Au1-P1 69.38(8).
Table 1. Crystallographic data, data collection and refinement.

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Highlights
•
•
•
•
two novel cationic phosphines bearing a η6-coordinated (η5-Cp)Fe+ moiety synthesized
one of these ligands was structurally characterized by X-ray structure analysis
a transition metal complex (gold) of such a ligand synthesized
structural characterization of the gold complex by X-ray structure analysis