Synthesis and auration of primary and di-primary heteroaryl-phosphines

Article abstract of DOI:10.1039/b415326j

Convenient high-yield syntheses of the primary and di-primary heteroaryl-phosphines R PH₂ and H₂P-R'-PH₂ (with R = 2-thienyl, 2-furyl, and R' = 2,5-thiophenediyl, 2,5-furandiyl, respectively) are presented. The products and a set of precursor molecules have been characterized by analytical and spectral data, and the crystal structures of selected molecules have been determined: 2-C₄H ₃O-PCl₂, 2,5-(CI₂P)₂C ₄H₂O, 2,5-[(Et₂N)₂P] ₂C₄H₂E (with E = O, S). In the crystals, the two molecules with -PCl₂ substituents adopt trans conformations, while the other two have the -P(NEt₂)₂ groups rotated into a twist conformation. The reaction of the thienyl compounds with tris[(tert-phosphine)gold]oxonium tetrafluoroborates gave almost quantitative yields of the tri- and hexanuclear gold complexes, respectively: {2-C ₄H₃S-P[Au(PR₃)]₃}⁺BF ₄^- and [2,5-{[(R₃P)Au]₃P} ₂C₄H₂S]2⁺(BF₄ ^-)₂, (R = Bu, Ph). The structures of the compounds with R₃P = Bu₃P ligands have been determined. In both cases the [2-C₄H_3/2S-P] units cap triangles of gold atoms in an array that can be described as three [Au(PR₃)]⁺ cations bridged by a phosphido dianion(RP)².

Full text of DOI:10.1039/b415326j

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F U L L P A P E R
Synthesis and auration of primary and di-primary
heteroaryl-phosphines
Stephan A. Reiter, Stefan D. Nogai and Hubert Schmidbaur*
Department Chemie, Technische Universita¨t Mu¨nchen, Lichtenbergstrasse 4, 85747, Garching,
Germany. E-mail: H.Schmidbaur@lrz.tum.de
Received 5th October 2004, Accepted 12th November 2004
First published as an Advance Article on the web 7th December 2004
Convenient high-yield syntheses of the primary and di-primary heteroaryl-phosphines R–PH2 and H2P–Rꢀ–PH2
(with R = 2-thienyl, 2-furyl, and Rꢀ = 2,5-thiophenediyl, 2,5-furandiyl, respectively) are presented. The products and
a set of precursor molecules have been characterized by analytical and spectral data, and the crystal structures of
selected molecules have been determined: 2-C4H3O–PCl2, 2,5-(Cl2P)2C4H2O, 2,5-[(Et2N)2P]2C4H2E (with E = O, S).
In the crystals, the two molecules with –PCl2 substituents adopt trans conformations, while the other two have the
–P(NEt2)2 groups rotated into a twist conformation. The reaction of the thienyl compounds with
tris[(tert-phosphine)gold]oxonium tetrafluoroborates gave almost quantitative yields of the tri- and hexanuclear gold
+
−
t
complexes, respectively: {2-C4H3S–P[Au(PR3)]3} BF4 and [2,5-{[(R3P)Au]3P}2C4H2S]2+(BF4−)2, (R = Bu, Ph). The
t
structures of the compounds with R3P = Bu3P ligands have been determined. In both cases the [2-C4H3/2S–P] units
cap triangles of gold atoms in an array that can be described as three [Au(PR3)]+ cations bridged by a phosphido
dianion (RP)2−.
simple heteroaryl compounds, with R = 2-furyl and 2-thienyl.
Tertiary phosphines R3P with these two substituents have been
explored extensively in an effort to accomplish fine-tuning of
ligand properties for transition metal catalysis. In these studies,
the thienyl substituent was found to resemble most closely the
conventional phenyl substituent, while the furyl group exhibits
stronger electron-withdrawing character.12
Introduction
There is currently a rapidly growing interest in primary phos-
phines RPH2.1 Owing to the two P–H reaction sites, not available
in tertiary phosphines R3P, molecules of this type can be used
as synthons for the preparation of phosphines with mixed sub-
stituents R1R2R3P as chiral ligands for coordination chemistry.2
Moreover, primary phosphines can be employed as reagents for
many chemical transformations, in which the P–H functions
are added to unsaturated substrates. This “hydrophosphination”
reaction is the analogue of the “hydrosilylation” reaction well
established in organosilicon chemistry. It may be carried out in
many catalytic variants leading to a large variety of products.3
RPH2 compounds can also be considered important pre-
cursors for phosphinidenes of the type RP,4 which are phos-
phorus analogues of carbenes: With a similar set of fron-
tier orbitals and a sextet of electrons at the functional site,
RP units can perform as terminal, bridging or capping ligands
to single metal atoms, pairs of metal atoms or multi-atom
clusters, respectively. Phosphinidenes are generally prepared
by reductive elimination from suitable precursors such as 7-
phosphanorbornadienes5 or phosphacyclopropenes.6 Alterna-
tive methods are based on the metallation and reduction of
dihalogenophosphines RPX2 with suitable (metallic) reductants,
or on halogeno(organo)phosphines RP(H)X which can undergo
reductive elimination of hydrogen halide. For their synthesis,
primary phosphines RPH2 are required.1,3,7,8 Finally, primary
phosphines can be metallated with electropositive metals (or
metal hydrides) to give phosphides RP(M)H and RPM2, and the
products can be used as reagents e.g. for metal halides to give
again the RP-bridged dinuclear compounds or the RP-capped
metal triangles or clusters.4,7–9
Our studies are also an extension of previous work13–15 on
2-thienyl-/2-furyl-silanes and -germanes, which are precursors
for the preparation of substituted poly(thiophenes) with inter-
esting photophysical properties. Phosphorus analogues of these
materials were investigated much less.16
Preparative results
2-Phosphinyl- and 2,5-di(phosphinyl)thiophene (2, 6)
(Dihalogenophosphinyl)thiophenes are the most obvious pre-
cursors for the preparation of the corresponding primary
phosphines 2 and 6 (Scheme 1). It is fortunate that several syn-
thetic pathways have been reported at least for the compounds
mono-substituted in the 2-position, including the particularly
convenient direct “phosphination” of thiophene under Friedel–
Crafts conditions, using e.g. a mixture of PCl3 and SnCl4, which
affords good yields of compound 1.17–19
In the present study it was found, however, that for the “di-
phosphination” of thiophene a procedure following the three-
step metallation route is necessary (Scheme 1). The 2,5-
dilithiation of thiophene (to give compound 3) requires a
n
slight excess of BuLi along with N,N,Nꢀ,Nꢀ-tetramethylethyl-
enediamine (TMEDA) as an auxiliary base.20–22 After reaction
of 3 with two equivalents of bis(diethylamino)chlorophosphine
high yields (83.5%) of the product 4 could be isolated by
crystallization (from hexane or dichloromethane, mp 61 ◦C).
This compound was converted into the tetrachloride 5 (95%
yield, mp −1 ◦C) by passing a stream of HCl gas through a
solution of 4 in hexane.
Primary phosphines thus are key starting materials for phos-
phinidene chemistry. Though direct elimination of molecular
hydrogen from RPH2 compounds to leave RP units has not
yet been observed on a preparative scale, there is evidence for
dehydrogenative P–P coupling of di-primary phosphines.10
However, as compared to the plethora of tertiary phosphines
R3P available in the literature, the collection of RPH2 com-
pounds is still very limited.1,11,12 This is particularly true for
compounds with substituents R other than alkyl or aryl. In
the present study we therefore explored the synthesis of a few
The chlorides 1 and 5 were finally reduced to the (di)primary
phosphines by LiAlH4 in diethyl ether. The products could be
isolated as colourless, distillable liquids [2: bp 155 ◦C, 92% yield;
6: bp 72 ◦C/0.9 mbar, mp −39 ◦C, 89% yield].
T h i s j o u r n a l i s
T h e R o y a l S o c i e t y o f C h e m i s t r y 2 0 0 5
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5
2 4 7
©

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Scheme 2 Preparation of 2-phosphinyl- and 2,5-di(phosphinyl)furans.
Scheme
1
Preparation of 2-phosphinyl- and 2,5-di(phosphinyl)-
The NMR spectra (in CD2Cl2) show extreme high-field 31P
thiophenes.
signals (ca. d −150 ppm) for the four primary phosphines (2, 6,
1
10, 14) which are split into triplets with large JPH coupling
constants (ca. 200 Hz). By contrast, the 31P resonances of
the dichlorophosphinyl compounds (1, 5, 9, 13) are shifted
into the downfield region around d +150 ppm, while those
of the diaminophosphinyl precursors (4, 8, 12) appear in an
intermediate region (ca. d 80 ppm). The 1H and 13C spectra show
no anomalies. The multiplicities of the signals of the 2-mono-
and 2,5-disubstituted compounds indicate that in solution the
molecules have virtual Cs and C2v symmetry, respectively, and no
further splitting is observed upon lowering the temperature to
ca. −80 ◦C. These results suggest that in solution the molecules
have symmetrical ground-state conformations or at least free
rotation of the functional groups about the P–C bonds.
2-Phosphinyl- and 2,5-di(phosphinyl)furan (10, 14)
The two target molecules in the furan series were synthesized
starting with furan as illustrated in Scheme 2. Mono- or
dilithiation followed by reaction with bis(diethylamino)chloro-
phosphine in the appropriate molar ratio gave the bis(diethyl-
amino)phosphinyl-substituted furans with the P-atoms regios-
electively introduced in the 2- and 2,5-positions, respectively
(8, 12). [It should be noted that the same reaction was
used to produce the tetraphenylated derivatives with the same
substitution pattern: 2,5-(Ph2P)2C4H2E, E = O,23 E = S.24]
These primary products could again be readily converted into
the corresponding dichlorophosphinyl compounds (9, 13) by
passing dry hydrogen chloride into their solutions in hexane.
The two compounds were purified by distillation to give 9 as a
colourless liquid (mp −40 ◦C) and 13 as a colourless crystalline
solid (mp 28 ◦C). Reduction of the compounds with LiAlH4 in
diethyl ether gave the (di)primary phosphines, of which 10 was
difficult to separate from the solvent by distillation. Experiments
with high-boiling ethers proved to offer no advantage, and only
small amounts of 10 could be isolated by GLC. However, the
azeotrope with diethyl ether (5 mol% 10, bp 35 ◦C/760 mm Hg)
is a good source of 10 for further transformations. Compound
14 was more readily purified and obtained as a colourless liquid
of bp 113 ◦C. Like the two phosphinylthiophenes (2, 6), both
phosphinylfurans are extremely malodorous and sensitive to
oxygen, igniting on the tip of a syringe or when spread on filter
paper.
Relevant spectral and structural data in the literature
1
The H NMR spectrum of the (dichlorophosphinyl)thiophene
1 (as a neat liquid) was investigated in a very early study,25 the
results of which are in satisfactory agreement with our own
data considering the different experimental conditions. (More
advanced NMR data are available for the difluorophosphinyl
analogue, 2-C4H3S–PF2.)26
Compound 1 was further studied (as a solid at 77 K)
by 35Cl NQR spectroscopy.27 The results indicate that two
inequivalent chlorine substituents are present in the crystal.
In recent work the earlier results have been confirmed and
used as a reference for quantum-chemical calculations of the
molecular conformation.28 Two structures with Cs symmetry
were considered, which have the sulfur atom in a cis or trans
orientation relative to the lone-pair of electrons at the P-atom.
From these calculations, there appears to be a slight preference
for the trans conformation. This result is in agreement with
the crystal structure data of tri(2-furyl)phosphine, in which
Compounds 1, 2, 4–6, 8–10 and 12–14 have been characterized
by analytical and spectroscopic data (Experimental section), and
the crystal structures have been determined for 4, 9, 12 and 13
(below).
2 4 8
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5

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each of the three furyl groups adopts the trans conformation
of its oxygen atom relative to the lone-pair of electrons at
the phosphorus atom. (The overall geometry approaches point
group C3v symmetry.)13
From a gas phase electron diffraction29 and a solution dipole
moment study30 of compound 1 conformations with different
dihedral angles between the thiophene plane and the plane
containing C1 and bisecting the Cl–P–Cl angle were obtained.
Starting from a trans arrangement of the sulfur atom and the
lone-pair of electrons at the P-atom (taken as 0◦), this angle is
given as 48 and 32◦, respectively.
Furan and thiophene bearing silyl (–SiH3) and germyl groups
(–GeH3) in the 2- and 2,5-positions have recently been studied
by quantum-chemical calculations.14,15 A ground state confor-
mation with Cs symmetry was found for the mono-substituted
compounds with one Si- or Ge-bound hydrogen atom in the
Z configuration (eclipsed) with the hydrogen atom at C3. For
the disubstituted compounds the ground state structures are
of C2v symmetry with the same conformational pattern. The
crystal structure of 2,5-(H3Si)2C4H2S has been determined and
slight distortions relative to the calculated geometry were found,
mainly a conrotatory movement of the two silyl groups shifting
the two eclipsed hydrogen atoms away from the molecular plane
by ca. 25◦ and resulting in a structure with C2 symmetry. This
deviation may be due to crystal packing effects which bring
the hydrogen atoms concerned in positions preferred for weak
interactions with the heterocyclic p-systems of neighbouring
molecules.
Fig. 1 Two projections of the molecular structure of 2-C4H3O–PCl2 (9).
Structural results
(a) ORTEP, 50% probability ellipsoids, with atomic numbering. (b) Arbi-
˚
2-(Dichlorophosphinyl)furan, 9, crystallizes in the orthorhom-
bic space group Pbca with Z = 8 molecules in the unit cell (at
143 K). The molecular structure approaches mirror symmetry,
with the –PCl2 group rotated away of the symmetrical position
by 9.06◦ (Fig. 1). The oxygen atom and the lone-pair of electrons
at the phosphorus atom are in trans positions as proposed for the
sulfur analogue 1 in the gas and solution phases on the basis of
electron diffraction and dipole moment studies,29,30 respectively,
and by theoretical calculations. There is also an analogy with
the calculated silyl- and germyl-furan structures.14,15
trary radii and hydrogen atoms omitted. Selected bond lengths (A), bond
angles and dihedral angles (◦): P1–Cl1 2.0643(10), P1–Cl2 2.0680(11),
P1–C1 1.776(3); Cl1–P1–Cl2 98.77(4), Cl1–P1–C1 99.80(9), Cl2–P1–C1
100.60(9); O1–C1–P1–Cl1 42.4(2), O1–C1–P1–Cl2 −58.5(2).
2,5-Bis(dichlorophosphinyl)furan, 13, crystallizes in the
¯
tetragonal space group P421m with Z = 2 molecules in the unit
cell (at 193 K). [Temperature-dependent studies have shown that
there appears to be a reversible transition into another phase
below ca. −86 ◦C (187 K), but this phenomenon was not in-
vestigated any further.] The molecules have crystallographically
imposed C2v symmetry with the –PCl2 groups in the same trans
conformation as observed (with a slight rotational distortion) for
9 (Fig. 2). This structure is further analogous to those calculated
for the 2,5-disilyl/digermyl-furans.14,15 The geometrical details
of 9 and 13 are in excellent agreement as shown for selected data
in the captions to Figs. 1 and 2.
2,5-Bis[bis(diethylamino)phosphinyl]-thiophene and -furan
(4 and 12) form monoclinic crystals (at 143 K), but these have
different space groups (P21/n and P21). In the latter there are
two independent molecules (I, II) in the asymmetric unit (Fig. 3),
while in the former only equivalent molecules are present
(Fig. 4). Except for the variations caused by the differences in the
parameters for oxygen and sulfur, the structures of molecules 4
and 12 (I/II) are very similar, and therefore no separate discus-
sion is required. None of the molecules has a crystallographically
imposed symmetry, but C2 symmetry is approached quite closely
with the twofold axis passing through the heteroatoms (O, S)
and bisecting their endocyclic angle. The –P(NEt2)2 groups are
rotated away from the trans conformations observed for 9 and 13
into twist conformations. This arrangement is probably induced
by steric effects: For structures with C2v symmetry (as observed
for 13) severe steric crowding is expected owing to the four bulky
–NEt2 groups (Figs. 3(b), 4(b)). For small substituents X = H,
Fig. 2 Two projections of the molecular structure of 2,5-(Cl2P)2C4H2O
(13); the molecule has C2v symmetry. (a) ORTEP, 50% probability
ellipsoids, with atomic numbering. (b) Arbitrary radii and hydrogen
˚
atoms omitted. Selected bond lengths (A), bond angles and dihedral
angles (◦): P1–Cl1 2.0464(15), P1–C1 1.788(6); Cl1–P1–Cl1ꢀ 99.86(10),
C1–P1–Cl1 98.95(9); O1–C1–P1–Cl1 −50.77(5).
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5
2 4 9

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Fig.
4
Two projections of the molecular structure of 2,5-
[(Et2N)2P]2C4H2S (4). (a) ORTEP, 50% probability ellipsoids, with
atomic numbering; hydrogen atoms omitted. (b) Arbitrary radii and
˚
hydrogen atoms omitted. Selected bond lengths (A), bond angles
Fig. 3 Molecular structure of 2,5-[(Et2N)2P]2C4H2O (12). Only one
out of two independent molecules is shown in two projections. (a)
ORTEP, 50% probability ellipsoids, with atomic numbering; hydrogen
atoms omitted. (b) Arbitrary radii and hydrogen atoms omitted.
and dihedral angles (◦): P1–N1 1.692(2), P1–N2 1.686(2), P1–C1
1.825(3), P2–N3 1.694(2), P2–N4 1.692(2), P2–C4 1.823(3); N1–P1–N2
113.42(12), N1–P1–C1 98.62(12), N2–P1–C1 100.38(12), N3–P2–N4
113.73(12), N3–P2–C4 98.34(12), N4–P2–C4 99.78(12); S1–C1–P1–N1
−46.64(18), S1–C1–P1–N2 −162.51(16), S1–C4–P2–N3 −49.25(18),
S1–C4–P2–N4 −165.23(15).
◦
˚
Selected bond lengths (A), bond angles and dihedral angles ( )
for the molecule shown in the figures: P1–N11 1.6857(11), P1–N12
1.6910(12), P1–C11 1.8181(13), P2–N21 1.6919(11), P2–N22 1.6896(11),
P2–C14 1.8210(13); N11–P1–N12 113.61(6), N11–P1–C11 98.62(6),
N12–P1–C11 98.60(6), N21–P2–N22 113.85(6), N21–P2–C14 97.92(6),
N22–P2–C14 99.34(6); O1–C11–P1–N11 53.09(10), O1–C11–P1–N12
168.72(9), O1–C14–P2–N21 165.42(9), O1–C14–P2–N22 49.52(10).
F, Cl in the –PX2 groups the C2v ground state should be valid.
Note that the individual molecules with C2 symmetry (4, 12) are
chiral, but that both enantiomers are present in the crystals.
Preparation and structure of gold(I) complexes
In order to provide a few examples for metallation of the new
primary heteroaryl-phosphines, the thiophenes 2 and 6 have
been converted into a set of four gold(I) complexes 15–18 with
tBu3P and Ph3P as auxiliary ligands (Scheme 3). The corre-
sponding tri(gold)oxonium tetrafluoroborates31 were employed
as reagents for the phosphines in an equimolar ratio with
dichloromethane as the solvent. The products were obtained
in nearly quantitative yields, with water as the sole by-product
(which, however, was not traced in the reaction mixtures). The
compounds are colourless (15, 16) and yellow (17, 18) solids
Scheme 3 Preparation of tri- and hexanuclear gold complexes.
of the thienyl substituent and three gold atoms. The gold atoms
t
are linearly two-coordinate each bearing a bulky Bu3P ligand
◦
with melting points between 100 and 150 C, soluble in polar
(Fig. 5). There are no discernible sub-van der Waals contacts
between the cations, the anions and the solvent molecules.
2,5-Bis{tris[(tri-tert-butylphosphine)gold(I)]phosphonio}thio-
phene bis(tetrafluoroborate), 16, forms cubic crystals, space
organic solvents without decomposition. Their composition
was confirmed by analytical and spectral data (Experimental
section), and the crystal structures of the two complexes with
the tBu3P ligands have been determined.
¯
group Im3 with Z = 12, in which the anions were found
In the 31P NMR spectra of the two complexes with the tBu3P
disordered. The dications have crystallographically imposed
C2v symmetry (Fig. 6) with dimensions very similar to those of
compound 15.
2
ligands (15, 16) a strong JPP coupling is observed (240 Hz,
in CD2Cl2 at 25 ◦C) between the central P-atom and the
ligand P-atoms indicating that there are no scrambling processes
operative in solution under these conditions. By contrast, for
the complexes with the PPh3 ligands (17, 18) this coupling is not
resolved owing to ligand exchange phenomena which cause line
broadening already at room temperature.
It is noteworthy that in both cases the tetrahedral angles Au–
P1–Au (average for 15 107.3◦) together with large Au–P1 bond
lengths (average for 15 2.313ꢀ) preclude any short aurophilic Au–
Au contacts. This observation is in agreement with previous find-
ings for the cations of aryl(trigold)phosphonium salts.32–36 By
contrast, there is evidence that tetragoldphosphonium cations
2-Thienyl-tris[(tri-tert-butylphosphine)gold(I)]phosphonium
tetrafluoroborate, 15, crystallizes as a 1 : 1 solvate with
dichloromethane which is disordered over two sites (triclinic,
+
{[(L)Au]4P} have a square-pyramidal structure of the type
already confirmed for the arsenic analogues.37 These cations
2+
¯
space group P1, Z = 2). The cations feature a tetrahedrally
can be further aurated to give square pyramidal {[(L)Au]5P}
2+
3+
coordinated central phosphorus atom (P1) surrounded by C1
or {[(L)6Au5]P} dications and even octahedral {[(L)Au]6P}
2 5 0
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5

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the –PX2 groups are in a trans conformation regarding the
relative positions of the heteroatoms (O, S) and the lone-pair
of electrons at the phosphorus atoms, while for the latter a twist
conformation leads to sterical relaxation.
The new (di)primary phosphines can be used as synthons
for the preparation of metal heteroaryl-phosphides in which
the PR unit is capping metal triangles. In the first of the two
examples presented in this study for which the structure has been
determined (15), the [2-C4H3S–P]2− anion is coordinated to
three gold atoms to give a tetrahedral 2-thienyl-tri(gold)-
+
phosphonium cation: {(2-C4H3S)P[Au(PtBu3)]3} . This cation
can also be viewed as an adduct of the 2-thienylphos-
phinidene unit (2-C4H3S–P) to the trinuclear cation
[Au3(PtBu3)3]+. The latter species is part of the taxonomy of gold
clusters and gold cluster cations41 and e.g. appears – capped
with a [Au(PtBu3)]+ cation – in the tetrahedral, tetranuclear
dications [Au4(PtBu3)4]2+.42 However, the quasi-tetrahedral Au–
P–Au angles and the associated large Au–Au distances in 15 (and
+
16) indicate that metal–metal bonding present in the {[(L)Au]3}
+
Fig. 5 Structure of the cation {2-C4H3S–P[Au(PtBu3)]3} in the
cation is quenched upon the capping by the RP unit.
tetrafluoroborate salt dichloromethane solvate (15). (ORTEP, 50%
probability ellipsoids for the core atoms, with atomic numbering.)
The same structural pattern is valid for the hexanuclear dica-
tion of complex 16 derived from the di-primary phosphine 6, and
the –P[Au(PR3)]3 units in 15 and 16 are virtually superimposible.
The NMR data of these units are also almost identical. In
◦
˚
Selected bond lengths (A), bond angles and dihedral angles ( ): Au1–P1
2.304(2), Au2–P1 2.313(2), Au3–P1 2.321(2), P1–C1 1.803(8), Au1–P3
2.316(2), Au2–P4 2.332(2), Au3–P2 2.318(2); Au1–P1–Au2 104.31(8),
Au1–P1–Au3 110.23(9), Au2–P1–Au3 107.48(8); S1–C1–P1–Au1
−159.2(5), S1–C1–P1–Au2 −40.0(7), S1–C1–P1–Au3 80.1(6).
t
16, the bulk of the Bu3P ligands provides efficient shielding
of the thiophene core unit and also retards any intermolecular
exchange processes in solution. This lends considerable thermal
stability to both compounds. With the smaller Ph3P ligands (17,
18) the scrambling processes become more rapid (on the NMR
time scale) and the thermal stability in solution is markedly
reduced. This behaviour parallels the properties of the related
arylphosphine complexes, which were also prepared with tBu3P
and Ph3P ligands.32–36
Experimental
General
All chemicals used as starting materials were commer-
cially available, except bis(diethylamino)chlorophosphine,43
[(tBu3PAu)3O]+BF4 (19)
and [(Ph3PAu)3O]+BF4 (20)
−
−
31a
31b,c
which were prepared according to the literature. All reactions
were carried out routinely in an atmosphere of dry and pure
nitrogen. All solvents were distilled from an appropriate drying
Fig. 6 Structure of the dication [2,5-{[(tBu3P)Au]3P}2C4H2S]2+ in the
bis(tetrafluoroborate) salt (16). (ORTEP, 50% probability ellipsoids for
the core atoms, with atomic numbering; the dication has C2v symmetr◦y.)
˚
˚
agent and stored over molecular sieves (4 A) and under
Selected bond lengths (A), bond angles and dihedral angles ( ):
Au1–P1 2.316(2), Au2–P1 2.308(4), P1–C1 1.798(13), Au1–P2 2.328(3),
Au2–P3 2.314(4); Au1–P1–Au2 105.59(11), Au1–P1–Au1ꢀꢀ 104.99(15);
S1–C1–P1–Au1 59.5(2).
nitrogen. Glassware was oven-dried and filled with nitrogen.
During reactions with gold compounds exposure to direct
sunlight was avoided. Elemental analyses were carried out in the
Mikroanalytisches Laboratorium des Anorganisch-chemischen
Instituts der Technischen Universita¨t Mu¨nchen. The C, H,
N percentages were routinely determined using a vario EL
elemental analyzer (elementar Analysensysteme GmbH). The P
content was determined photometrically (as the molybdate) on
an UV-160 spectrophotometer (Shimadzu). Mass spectra were
recorded on a HP 5971A (Hewlett-Packard) spectrometer using
EI at 70 eV as an ionization method. For the gold compounds
a Finnigan MAT 90 spectrometer (positive FAB source; matrix
material 4-nitrobenzyl alcohol) was employed. NMR spectra
were obtained at room temperature on JEOL JNM-GX-400 or
JEOL 400 Eclipse spectrometers. Chemical shifts are reported
in d values relative to the residual solvent resonances of CD2Cl2
(1H,13C). 31P, 11B and 19F NMR spectra are referenced to external
aqueous H3PO4 (85%), BF3·OEt2 and CFCl3, respectively. GC-
MS analyses of the reaction mixtures were carried out on a
HP 5890 Series II (Hewlett-Packard) gas chromatograph with a
HP 5971A mass-selective detector. Capillary Column (Agilent
Technologies): HP-1 (Crosslinked Methyl Siloxane) 12.5 m ×
0.2 mm × 0.33 lm Film Thickness, HP Part No. 19091-
60312.
trications, where the edges of the PAun polyhedra are short
enough for aurophilic bonding.38–40
Conclusions
Primary phosphines are useful synthons for the generation
of organophosphinidenes [RP] (analogues of carbenes) and
organophosphide dianions [RP]2−. Satisfactory methods of
preparation are available for only a very limited number of
prototypes. In the present work it has now been shown that
primary heteroaryl-phosphines 2 and 10 [R–PH2 (R = 2-thienyl,
2-furyl)] and the corresponding di-primary phosphines 6 and 14
[H2P–Rꢀ–PH2 (Rꢀ = 2,5-thiophenediyl, 2,5-furandiyl)] can be
readily prepared in convenient high-yield syntheses as stable,
distillable compounds (Schemes 1 and 2).
Based on crystal structures of a group of precursor molecules
(9, 13, 4, 12), and on analogies to reference compounds known
in the literature,10–15,19,27–30 the compounds can be assigned
molecular structures with approximate Cs and C2v or (with
bulky groups) C2 symmetry, respectively. In the former two,
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5
2 5 1

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Syntheses
(EI) m/z 286 [M]+, 251 (100%) [M − Cl]+, 214 [M − 2Cl]+, 183
[M − PCl2]+, 148 [M − PCl2 − Cl]+, 113 [M − PCl2 − 2Cl]+,
101 [PCl2]+. Calc. for C4H2Cl4P2S (285.88): C, 16.81; H, 0.71; P,
21.67. Found: C, 16.75; H, 0.78; P, 21.38%.
2-(Dichlorophosphinyl)thiophene, 1. The preparation fol-
lowed a literature procedure;17 for analyti◦cal data see also ref. 25.
Complementary data: NMR (CDCl3, 25 C), 31P{ H}: 145.5 (s).
1
1
13C{ H}: 142.8 (d, 1JCP = 72.3 Hz, C2), 135.9 (d, 3JCP = 2.3 Hz,
2,5-Di(phosphinyl)thiophene, 6. A solution of 5 (18.05 g,
63.1 mmol) in diethyl ether (100 mL) was added slowly to a
stirred suspension of LiAlH4 (19.17 g, 505.1 mmol) in diethyl
ether (500 mL) at −78 ◦C. The reaction mixture was then allowed
to warm to room temperature and stirred for 12 h. For workup
C5), 135.7 (d, 2JCP = 43.8 Hz, C3), 127.8 (d, 3JCP = 8.5 Hz, C4).
1H: 7.84 (dd, 3JHH = 4.8 Hz, 4JHH = 1.1 Hz, 1H, H5), 7.64 (ddd,
3JHP = 7.0 Hz, JHH = 3.7 Hz, JHH = 1.0 Hz, 1H, H3), 7.13
3
4
3
3
4
(ddd, JHH = 4.8 Hz, JHH = 3.8 Hz, JHP = 2.0 Hz, 1H, H4).
MS (EI) m/z 184 [M]+, 149 (100%) [M − Cl]+, 114 [M − 2Cl]+,
101 [PCl2]+.
◦
degassed water (120 mL) was added dropwise at 0 C and the
mixture stirred at room temperature for 1 h. The precipitate was
separated and extracted with diethyl ether (2 × 100 mL), and the
combined organic phases were dried over MgSO4. Evaporation
of the solvents in vacuo yielded a colourless liquid: 8.35 g, 89.3%
yield, bp 72 ◦C (0.9 mbar), mp −39 ◦C. NMR (CD2Cl2, 25 ◦C),
2-Phosphinylthiophene, 2.
A solution of 1 (23.15 g,
125.1 mmol) in diethyl ether (100 mL) was added slowly to
a stirred suspension of LiAlH4 (19.00 g, 500.7 mmol) in diethyl
ether (500 mL) at −78 ◦C. The reaction mixture was then allowed
to warm to room temperature and stirred for 12 h. For workup
1
1
31P{ H}: −152.4 (s). 31P: −152.4 (tm, 1JPH = 207.5 Hz). 13C{ H}:
2
3
138.8 (dd, JCP = 27.5 Hz, JCP = 8.3 Hz, C3/4), 132.1 (dd,
1JCP = 25.4 Hz, 3JCP = 2.6 Hz, C2/5). 1H: 7.17 (m, A-part of an
AA‘XX’ spin system, 2H, H3/4), 4.08 (d, 1JHP = 207.3 Hz, 4H,
PH2). MS (EI) m/z 148 [M]+, 147 [M − H]+, 146 [M − 2H]+,
115 (100%) [M − PH2]+, 114 [M − PH2 − H]+, 113 [M − PH2 −
2H]+. Calc. for C4H6P2S (148.10): C, 32.44; H, 4.08; P, 41.83.
Found: C, 32.41; H, 4.19; P, 41.82%.
◦
degassed water (120 mL) was added dropwise at 0 C and the
mixture stirred at room temperature for 1 h. The precipitate was
separated and extracted with diethyl ether (2 × 100 mL), and the
combined organic phases were dried over MgSO4. Distillation
yieldeda colourless liquid:13.32g, 91.7%yield, bp 155 ◦C. NMR
(CDCl3, 25 ◦C), 31P{ H}: −151.3 (s). 31P: −151.3 (tm, JPH
=
1
1
207.4 Hz). 13C{ H}: 137.5 (d, 2JCP = 27.7 Hz, C3), 131.9 (s, C5),
1
128.0 (d, 3JCP = 8.5 Hz, C4), 124.1 (d, 1JCP = 23.1 Hz, C2). 1H:
2-[Bis(diethyl-amino)phosphinyl]furan, 8. The preparation of
2-furyllithium 7 was based on a literature procedure.44 A solution
of nBuLi (77 mL, 123 mmol, 1.6 M in hexane) was slowly added
to THF (77 mL) at 0 ◦C and subsequently furan (10.85 g,
159 mmol) was added at the same temperature. The reaction
mixture was allowed to warm to room temperature and stirring
was continued for 20 min.
3
4
7.52 (dd, JHH = 5.1 Hz, JHH = 0.7 Hz, 1H, H5), 7.32 (ddd,
3JHP = 5.3 Hz, JHH = 3.8 Hz, JHH = 0.8 Hz, 1H, H3), 7.08
3
4
3
3
4
(ddd, JHH = 5.1 Hz, JHH = 3.7 Hz, JHP = 1.5 Hz, 1H, H4),
1
4.15 (d, JHP = 207.2 Hz, 2H, PH2). MS (EI) m/z 116 (100%)
[M]+, 115 [M − H]+, 114 [M − 2H]+. Calc. for C4H5PS (116.12):
C, 41.37; H, 4.34; P, 26.67. Found: C, 41.80; H, 4.45; P, 26.36%.
Bis(diethylamino)chlorophosphine (29.75 g, 141 mmol) was
2,5-Bis[bis(diethylamino)phosphinyl]thiophene, 4. The pre-
paration of 2,5-dilithiothiophene 3 was based on literature
procedures.20–22 A solution of nBuLi (128 mL, 205 mmol, 1.6 M in
hexane) was added to a solution of TMEDA (23.80 g, 205 mmol)
in hexane (180 mL) at room temperature and the solution stirred
for 30 min. After addition of thiophene (6.90 g, 82 mmol)
the reaction mixture was refluxed for 3 h and allowed to
cool to 0 ◦C before bis(diethylamino)chlorophosphine (43.20 g,
205 mmol) was added slowly and the reaction mixture allowed
to warm to room temperature with stirring over a period of 4 h.
The precipitate was separated and extracted with hexane (2 ×
100 mL), and the solvents were evaporated from the combined
organic phases in vacuo. The residue was dissolved in the
minimum amount of hexane and stored at −30 ◦C to precipitate
colourless crystals: 29.61 g, 83.5% yield, mp 61 ◦C. Block-
shaped single crystals could be◦obtained by recrystallization
◦
slowly added at −78 C and the reaction mixture was allowed
to warm to room temperature and stirred for 12 h. The
residue remaining upon evaporation of the solvent in vacuo
was extracted with hexane (200, 100 mL). Evaporation of
the combined hexane extracts in vacuo yielded a brown oily
liquid, which contained only small amounts of bis(diethyl-
amino)chlorophosphine, tris(diethylamino)phosphine and (di-
1
ethylamino)(2-furyl)chlorophosphine. 31P{ H} NMR (hexane,
25 ◦C): 80.7 (s). MS (EI) m/z 242 [M]+, 170 (100%) [M − NEt2]+,
99 [M − 2NEt2 + H]+, 72 [NEt2]+.
2-(Dichlorophosphinyl)furan, 9. A solution of the above
product (8, with impurities) in hexane (500 mL) was cooled to
0 ◦C and saturated with gaseous HCl. The reaction mixture was
stirred for 1 h, again saturated with gaseous HCl and stirred for
1 h. This procedure was repeated until the supernatant solution
remained clear upon further addition of HCl. The reaction
mixture was then allowed to warm to room temperature and
stirred for 12 h. The diethylammonium chloride precipitate
was separated and extracted with hexane (2 × 100 mL).
Distillation of the combined organic phases yielded a colourless
1
1
from CH2Cl2. NMR (CD2Cl2, 25 C), 31P{ H}: 87.6 (s). 13C{ H}:
149.7 (d, 1JCP = 5.4 Hz, C2/5), 132.0 (d, 2JCP = 15.4 Hz, C3/4),
43.0 (d, 2JCP = 17.7 Hz, CH2), 14.9 (d, 3JCP = 2.3 Hz, CH3). 1H:
6.97 (m, A-part of an AA‘XX’ spin system, 2H, H3/4), 3.14 (m,
16H, CH2), 1.11 (t, 3JHH = 7.0 Hz, 24H, CH3). MS (EI) m/z 432
[M]+, 360 [M − NEt2]+, 257 [M − P(NEt2)2]+, 175 [P(NEt2)2]+.
Calc. for C20H42N4P2S (432.59): C, 55.53; H, 9.79; N, 12.95; P,
14.32. Found: C, 55.49; H, 9.81; N, 12.89; P, 14.20%.
liquid: 13.94 g, 67.0% yield (based on BuLi), bp 181 ◦C, mp
n
−40 ◦C. Block-shaped single crystals were grown by slow cooling
◦
1
1
of the melt. NMR (CD2Cl2, 25 C), 31P{ H}: 123.7 (s). 13C{ H}:
152.6 (d, 1JCP = 68.4 Hz, C2), 150.4 (d, 3JCP = 3.1 Hz, C5), 122.7
(d, 2JCP = 36.1 Hz, C3), 111.7 (d, 3JCP = 6.1 Hz, C4). 1H: 7.85
2,5-Bis(dichlorophosphinyl)thiophene, 5. A solution of 4
(29.20 g, 67.5 mmol) in hexane (500 mL) was cooled to 0 ◦C and
saturated with gaseous HCl. The reaction mixture was stirred for
1 h, again saturated with gaseous HCl and stirred for 1 h. This
procedure was repeated until the supernatant solution remained
clear upon further addition of HCl. The reaction mixture was
then allowed to warm to room temperature and stirred for 12 h.
The diethylammonium chloride precipitate was separated and
extracted with hexane (2 × 100 mL). Evaporation of the solvents
from the combined organic phases in vacuo yielded a colourless
3
4
(dd, A-part of an ABCX spin system, JHH = 1.8 Hz, JHH
=
0.7 Hz, 1H, H5), 7.19 (m, B-part, 1H, H3), 6.56 (m, C-part, 1H,
H4). MS (EI) m/z 168 [M]+, 133 (100%) [M − Cl]+, 101 [PCl2]+,
98 [M − 2Cl]+. Calc. for C4H3Cl2OP (168.95): C, 28.44; H, 1.79;
P, 18.33. Found: C, 28.44; H, 1.72; P, 18.24%.
2-Phosphinylfuran, 10. A solution of 9 (13.40 g, 79.3 mmol)
in diethyl ether (60 mL) was added slowly to a stirred suspension
of LiAlH4 (12.00 g, 316.2 mmol) in diethyl ether (300 mL) at
−78 ◦C. The reaction mixture was then allowed to warm to room
temperature and stirred for 12 h. For workup degassed water
(70 mL) was added dropwise at 0 ◦C and the mixture stirred at
room temperature for 1 h. The precipitate was separated and
oily liquid: 18.33 g, 95.0% yield, mp −1 ◦C. NMR (CD2Cl2,
◦
1
1
1
25 C), 31P{ H}: 143.3 (s). 13C{ H}: 152.6 (d, JCP = 77.6 Hz,
2
3
1
C2/5), 135.6 (dd, JCP = 40.0 Hz, JCP = 6.9 Hz, C3/4). H:
7.66 (m, A-part of an AA‘XX’ spin system, 2H, H3/4). MS
2 5 2
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5

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extracted with diethyl ether (2 × 50 mL), and the combined
organic phases were dried over MgSO4. 10 could not be isolated
from the diethyl ether solution by distillation, but formed an
stirred suspension of LiAlH4 (19.00 g, 500.7 mmol) in diethyl
ether (500 mL) at −78 ◦C. The reaction mixture was then allowed
to warm to room temperature and subsequently stirred for 12 h.
For workup degassed water (120 mL) was added dropwise at
◦
azeotrope: Bp 35 C, ca. 5 mol% of 10. In the GC separation,
◦
using columns as specified in the general part above, compound
0 C and the mixture stirred at room temperature for 1 h. The
10 ◦had a retention time of 1.1 min at 37 ◦C. NMR (CD2Cl2,
precipitate was separated and extracted with diethyl ether (2 ×
100 mL), and the combined organic phases were dried over
MgSO4. 14 was isolated by fractiona◦l distillation: bp 113 ◦C,
1
25 C), 31P{ H}: −164.2 (s). 31P: −164.2 (tm, 1JPH = 209.3 Hz).
1
13C{ H}: 147.8 (s, C5), 144.5 (d, 1JCP = 20.8 Hz, C2), 122.6 (d,
2JCP = 25.4 Hz, C3), 111.5 (d, 3JCP = 6.1 Hz, C4). 1H: 7.61 (dd,
3.60 g, 43% yield. NMR (CD2Cl2, 25 C), 31P{ H}: −161.9 (s).
1
A-part of an ABCX spin system, 3JHH = 1.8 Hz, 4JHH = 0.7 Hz,
31P: −161.9 (t, JPH = 210.1 Hz). 13C{ H}: 149.6 (d, JCP
=
1
1
1
3
1H, H5), 6.70 (m, B-part, 1H, H3), 6.37 (dt, C-part, JHH
3.3 Hz, 3JHH = 1.8 Hz, 4JHP = 1.8 Hz, 1H, H4), 3.89 (d, 1JHP
=
=
21.5 Hz, C2/5), 123.3 (dd, 2JCP = 23.8 Hz, 3JCP = 6.1 Hz, C3/4).
1H: 6.66 (m, A-part of an AA‘XX’ spin system, 2H, H3/4), 3.92
(d, 1JHP = 210.3 Hz, 4H, PH2). MS (EI) m/z 132 [M]+, 131 [M −
H]+, 130 [M − 2H]+, 99 (100%) [M − PH2]+, 98 [M − PH2 −
H]+, 97 [M − PH2 − 2H]+.
209.1 Hz, 2H, PH2). MS (EI) m/z 100 [M]+, 99 (100%) [M −
H]+, 98 [M − 2H]+.
2,5-Bis[bis(diethylamino)phosphinyl]furan, 12. The prepara-
tion of 2,5-dilithiofuran 11 was based on a modified literature
procedure.15 A solution of tBuLi (208 mL, 312 mmol, 1.5 M in
pentane) was slowly added to diethyl ether (400 mL) at −78 ◦C
and subsequently a solution of furan (10.50 g, 154 mmol) in
diethyl ether (80 mL) was added at the same temperature. The
reaction mixture was stirred for 1 h at −78◦Cand then allowedto
warm slowly to room temperature. During this period the yellow
solution changed to a white suspension, which was stirred for
additional 1.5 h at room temperature. (In a separate experiment,
stirring for a longer time at room temperature resulted in a
darkening of the white suspension indicating decomposition.)
Bis(diethylamino)chlorophosphine (74.00 g, 351 mmol) was
{2-C4H3S–P[Au(PtBu3)]3}+BF4−, 15. A solution of phos-
phine 2 (16.3 mg, 0.14 mmol) in CH2Cl2 (10 mL) was slowly
added to a stirred solution of oxonium salt 19 (182.1 mg,
0.14 mmol) in the same solvent (20 mL) at −78 ◦C. The
colourless reaction mixture was warmed to ambient temperature
after 2 h and concentrated in vacuo. Upon addition of pentane
(50 mL) a colourless oil separated, which was dried in vacuo
to yield 15 as a polycrystalline solid: 191.5 mg, 97.8% yield,
mp 130 ◦C (decomposition). Colourless, block-shaped single
crystals could be grown by slow diffusion of diethyl ether vapour
◦
into a solution of the compound in CH2Cl2 at −30 C. NMR
(CD2Cl2, 25 ◦C), 31P{ H}: 99.3 (d, JPP = 240.3 Hz, Bu3P),
1
2
t
◦
2
slowly added at −78 C and the reaction mixture was allowed
−24.4 (q, JPP = 240.3 Hz, PAu3). 31P: 99.3 (d × 28 (2 × 18
to warm to room temperature and subsequently stirred for
12 h. The residue remaining upon evaporation of the solvent
in vacuo was extracted with hexane (250 and 100 mL) and the
combined hexane extracts were concentrated in vacuo and stored
lines resolved), 2JPP = 240.3 Hz, 3JPH = 13.4 Hz, tBu3P), −24.4
1
(qd, 2JPP = 240.3 Hz, 3JPH = 7.1 Hz, PAu3). 13C{ H}: 135.5 (m),
1
2
128.1 (m), 40.0 (d, JCP = 13.8 Hz, C(CH3)3), 32.7 (d, JCP
=
4.6 Hz, C(CH3)3). 1H: 7.12 (ddd, 3JHH = 5.1 Hz, 4JHP = 2.2 Hz,
4JHH = 1.1 Hz, 1H, H5), 7.03 (dd, 3JHP = 7.3 Hz, 3JHH = 3.3 Hz,
1H, H3), 6.94 (dd, 3JHH = 5.1 Hz, 3JHH = 3.3 Hz, 1H, H4), 1.53
◦
at −30 C to precipitate colourless, block-shaped crystals. The
crystals melted when warmed to room temperature to give a
colourless oi◦ly liquid: 45.81 g, 71.3% yield, mp 4 ◦C. NMR
1
1
(d, 3JHP = 13.6 Hz, 81H, C(CH3)3). 11B{ H}: −2.1 (s). 19F{ H}:
1
1
1
(CD2Cl2, 25 C), 31P{ H}: 79.6 (s). 13C{ H}: 160.6 (dd, JCP
=
−153.4 (s). MS (FAB) m/z 1312.4 (100%) [M]+, 1255.3 (15.4)
6.9 Hz, 3JCP = 3.1 Hz, C2/5), 117.4 (d, 2JCP = 16.1 Hz, C3/4),
43.4 (d, 2JCP = 17.7 Hz, CH2), 15.0 (d, 3JCP = 2.3 Hz, CH3). 1H:
6.49 (m, A-part of an AA‘XX’ spin system, 2H, H3/4), 3.12 (m,
16H, CH2), 1.10 (t, 3JHH = 7.2 Hz, 24H, CH3). MS (EI) m/z 416
[M]+, 344 [M − NEt2]+, 241 [M − P(NEt2)2]+, 175 [P(NEt2)2]+.
Calc. for C20H42N4OP2 (416.52): C, 57.67; H, 10.16; N, 13.45; P,
14.87. Found: C, 57.58; H, 9.98; N, 13.37; P, 14.84%.
[M − Bu]+, 1110.1 (10.8) [M − PtBu3]+, 913.0 (13.9) [M −
t
AuPtBu3]+. Calc. for C40H84Au3BF4P4S (1398.76): C, 34.35; H,
6.05; P, 8.86. Found: C, 34.01; H, 6.18; P, 8.83%.
[2,5-C4H2S{P[Au(PtBu3)]3}2]2+(BF4−)2, 16. As described for
complex 15, compound 16 was prepared from phosphine 6
(9.4 mg, 0.06 mmol) and oxonium salt 19 (165.1 mg, 0.13 mmol);
colourless, polycrystalline solid: 165.7 mg, 96.2% yield, mp
◦
2,5-Bis(dichlorophosphinyl)furan, 13.
A
solution of 12
130 C (decomposition). Colourless, block-shaped single crys-
(45.37 g, 108.9 mmol) in hexane (500 mL) was cooled to 0 ◦C and
saturated with gaseous HCl. The reaction mixture was stirred for
1 h, again saturated with gaseous HCl and stirred for 1 h. This
procedure was repeated until the supernatant solution remained
clear upon further addition of HCl. The reaction mixture was
then allowed to warm to room temperature and stirred for 12 h.
The diethylammonium chloride precipitate was separated and
extracted with hexane (2 × 100 mL). Evaporation of the solvent
from the combined organic phases and distillation of the residue
tals could be grown by slow diffusion of diethyl ether vapour
◦
into a solution of the compound in acetone at −30 C. NMR
(CD2Cl2, 25 ◦C), 31P{ H}: 99.1 (d, JPP = 240.9 Hz, Bu3P),
1
2
t
−23.2 (q, JPP = 240.9 Hz, PAu3). 31P: 99.1 (d × 28 (2 × 18
2
lines resolved), 2JPP = 240.9 Hz, 3JPH = 13.4 Hz, tBu3P), −23.2
1
(qd, 2JPP = 240.9 Hz, 3JPH = 7.9 Hz, PAu3). 13C{ H}: 143.7 (d,
1JCP = 11.4 Hz, CP), 136.8 (m, A-part of an AXXꢀ spin system,
CH), 40.0 (d, 1JCP = 14.0 Hz, C(CH3)3), 32.7 (s, C(CH3)3). 1H:
6.88 (m, A-part of an AA‘XX’ spin system, 2H, CH), 1.52 (d,
◦
1
1
in vacuo yielded a colourless oily liquid. On cooling to 0 C a
3JHP = 13.4 Hz, 162H, C(CH3)3). 11B{ H}: −2.1 (s). 19F{ H}:
polycrystalline solid was obtained: 19.06 g, 64.9% yield, bp 95 ◦C
−153.2 (s). MS (FAB) m/z 1270.9 (54.7%) [M]2+, 1242.2 (40.6)
◦
t
(0.9 mbar), mp 28 C. Colourless, block-shaped single crystals
[M − Bu]2+, 1169.5 (6.9) [M − PtBu3]2+, 1070.9 (16.1) [M −
formed upon melting the solid, leaving only a small amount of
the polycrystalline material as seed crystals and storage of the
AuPtBu3]2+, 601.8 (15.1) [Au(PtBu3)2]+, 399.5 (35.8) [AuPtBu3]+.
Calc. for C76H164Au6B2F8P8S (2713.38): C, 33.64; H, 6.09; P, 9.13.
Found: C, 33.41; H, 6.09; P, 9.02%.
◦
1
sample at room temperature. NMR (CD2Cl2, 25 C), 31P{ H}:
124.6 (s). 13C{ H}: 160.1 (dd, JCP = 71.5 Hz, JCP = 2.3 Hz,
1
1
3
{2-C4H3S–P[Au(PPh3)]3}+BF4−, 17. As described for com-
plex 15, compound 17 was prepared from phosphine 2 (17.3 mg,
0.15 mmol) and oxonium salt 20 (220.6 mg, 0.15 mmol);
yellow, polycrystalline solid: 231.2 mg, 98.3% yield, mp 108 ◦C
2
3
1
C2/5), 121.6 (dd, JCP = 26.9 Hz, JCP = 3.8 Hz, C3/4). H:
7.24 (m, A-part of an AA‘XX’ spin system, 2H, H3/4). MS
(EI) m/z 270 [M]+, 233 (100%) [M − Cl]+, 198 [M − 2Cl]+, 167
[M − PCl2]+, 132 [M − PCl2 − Cl]+, 101 [PCl2]+, 97 [M − PCl2 −
2Cl]+. Calc. for C4H2Cl4OP2 (269.82): C, 17.81; H, 0.75; P, 22.96.
Found: C, 17.88; H, 0.83; P, 23.07%.
(decomposition). NMR (CD2Cl2, 25 ◦C), 31P{ H}: 45.6 (br s,
1
1
Ph3P), −34.8 (br s, PAu3). 13C{ H}: 138.3 (m), 136.8 (m), 134.6
(d, 2JCP = 13.1 Hz, o-C6H5), 132.4 (s, p-C6H5), 129.8 (d, 3JCP
=
2,5-Di(phosphinyl)furan, 14. A solution of 13 (17.00 g,
63.0 mmol) in diethyl ether (100 mL) was added slowly to a
9.2 Hz, m-C6H5), (ipso-C6H5 covered by m-C6H5), 128.6 (m).
1
1H: 7.68 − 7.32 (m, 48H, C6H5 + H3/4/5). 11B{ H}: −2.1 (s).
D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5
2 5 3

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Table 1 Crystal data, data collection and structure refinement for compounds 4, 9, 12, 13, 15 and 16
4
9
12
13
15
16
Empirical formula
C20H42N4P2S
C4H3Cl2OP
C20H42N4OP2
C4H2Cl4OP2
C40.76H85.51Au3BCl1.51F4P4S C76H164Au6B1.67F6.67P8S
M
432.58
Monoclinic
P21/n
13.2635(3)
8.0961(2)
23.8229(5)
168.95
416.52
269.80
1463.08
Triclinic
P1
2684.37
Cubic
Im3
31.4590(6)
31.4590
31.4590
90
90
90
31134(1)
1.718
12
Crystal system
Space group
Orthorhombic Monoclinic
Pbca
10.4742(3)
18.5825(6)
6.8165(2)
Tetragonal
¯
¯
¯
P21
P421m
˚
˚
˚
a/A
b/A
10.8376(1)
15.8571(2)
14.3424(2)
9.0431(2)
9.0431
6.2387(2)
12.7063(6)
14.5754(8)
16.2534(5)
102.894(3)
106.329(3)
97.318(3)
2757.1(2)
1.762
c/A
a/◦
b/◦
c /◦
102.190(2)
90
90.2038(6)
90
3
˚
V/A
2500.5(1)
1.149
4
1326.74(7)
1.691
8
2464.77(5)
1.122
4
912
143(2)
55572
510.19(2)
1.756
2
264
193(2)
13348
Dc/g cm−3
Z
2
F(000)
T/K
Refls. measured
Refls. unique
944
672
1420
143(2)
46585
9557
15580
143(2)
92884
4401
143(2)
55746
1197
143(2)
324682
5040
9043
423
Parameters/restraints 252/0
85/0
0.037
0.098
823/1
0.024
0.063
a = 0.0349
b = 0.2103
0.139/−0.198
32/0
0.036
0.096
a = 0.0419
b = 0.2320
0.198/−0.293
556/6
0.047
0.112
a = 0.0267
b = 17.2384
2.587/−2.924
285/10
0.052
0.115
a = 0.0000
b = 1600.2937
3.341/−1.369
R1 [I ≥ 2r(I)]
0.052
0.144
wR2a
Weighting scheme
a = 0.0626
a = 0.0398
b = 3.9640
b = 1.5227
−3
˚
rfin(max./min.)/e A
0.820/−0.404 0.372/−0.355
2
2
a wR2 = {R[w(Fo − Fc2)2]/R[w(Fo2)2]}1/2; w = 1/[r2(Fo2) + (ap)2 + bp]; p = (Fo + 2Fc2)/3.
1
19F{ H}: −153.3 (s). MS (FAB) m/z 1490.9 (9.4%) [M]+,
1228.5 (2.7) [M − PPh3]+, 720.4 (100) [Au(PPh3)2]+, 458.4 (89.0)
[AuPPh3]+. Calc. for C58H48Au3BF4P4S (1578.67): C, 44.13; H,
3.06; P, 7.85. Found: C, 43.91; H, 2.95; P, 7.79%.
owing to a lack of other suitable positions, and are therefore
disordered. It was not possible to locate a total of 0.5 [BF4]− per
asymmetric unit required for a charge neutrality. The structure
model therefore is to be considered as incomplete regarding the
anionic components.
The hydrogen atoms in 9 and 12 were located and refined with
isotropic displacement parameters, those in 4, 13, 15 and 16 were
calculated in ideal positions and refined using a riding model.
In the structure of 15 all C–Cl bond lengths of the solvent
molecules and in the structure of 16 all B–F bond lengths of the
[BF4]− anions were restrained to be equal.
An absorption correction was carried out for 15 using
DELABS, as part of the PLATON suite of programs.46 The
Flack parameter is 0.00(3) for 12 and 0.6(3) for 13. Further
information on crystal data, data collection and structure
refinement is summarized in Table 1.
[2,5-C4H2S{P[Au(PPh3)]3}2]2+(BF4−)2, 18. As described for
complex 15, compound 18 was prepared from phosphine
6 (11.9 mg, 0.08 mmol) and oxonium salt 20 (237.9 mg,
0.16 mm◦ol); yellow, polycrystalline solid: 237.5 mg, 96.2% yield,
◦
mp 108 C (decomposition). NMR (CD2Cl2, 25 C), 31P{ H}:
1
46.4 (br s, Ph3P), −35.3 (br s, PAu3). 13C{ H}: 141.6 (d, 1JCP
=
1
14.5 Hz, CP), 138.4 (m, A-part of an AXXꢀ spin system, CH),
2
134.5 (d, JCP = 5.2 Hz, o-C6H5), 132.4 (s, p-C6H5), 129.8 (s,
1
m-C6H5), (ipso-C6H5 covered by m-C6H5). H: 7.68 − 7.32 (m,
90H, C6H5), 7.20 (m, A-part of an AA‘XX’ spin system, 2H,
CH). 11B{ H}: −2.1 (s). 19F{ H}: −153.3 (s). MS (FAB) m/z
720.4 (100%) [Au(PPh3)2]+, 458.4 (70.7) [AuPPh3]+. Calc. for
C112H92Au6B2F8P8S (3073.19): C, 43.77; H, 3.02; P, 8.06. Found:
C, 43.28; H, 3.16; P, 8.18%.
1
1
CCDC reference numbers 252034-252039.
See http://www.rsc.org/suppdata/dt/b4/b415326j/ for cry-
stallographic data in CIF or other electronic format.
Determination of the crystal structures
Acknowledgements
Specimens of suitable quality and size of 4, 9, 12, 13, 15
and 16 were mounted on the ends of quartz fibers in inert
perfluoropolyalkylether and used for intensity data collection
on a Nonius DIP2020 diffractometer, employing graphite-
monochromated Mo-Ka radiation. Crystals of 13 undergo a
reversible phase transition between −84 and −88 ◦C. Due to loss
of lattice symmetry the low temperature phase is then multiple
twinned. The structures were solved by a combination of direct
methods (SHELXS-97) and difference-Fourier syntheses and re-
fined by full matrix least-squares calculations on F2 (SHELXL-
97).45 The thermal motion was treated anisotropically for all
non-hydrogen atoms.
The lattice of 15 contains solvent molecules (CH2Cl2) which
are disordered over two sites. The independent refinement of the
site occupation factors results in an occupation of only 0.76 for
the sum of both sites.
After the initial refinement of the cationic part of the crystal
structure of 16 the highest residual electron densities were
found in the vicinity of special positions with a local symmetry
not fulfilling the requirements for tetrahedral symmetry. The
[BF4]−-anions were nevertheless assigned to these positions,
This work was supported by Deutsche Forschungsgemeinschaft,
Fonds der Chemischen Industrie and Deutscher Akademischer
Austauschdienst. The authors are indebted to Degussa AG and
Heraeus GmbH for the donation of chemicals.
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D a l t o n T r a n s . , 2 0 0 5 , 2 4 7 – 2 5 5
2 5 5