Synthesis and optoelectronic properties of transition metal complexes incorporating dithieno[3,2-b:2′,3′-d]phosphole ligands

Article abstract of DOI:10.1039/b509277a

A series of dithieno[3,2-b:2′,3′-d]phosphole-based transition metal complexes, including Au, Fe, Pt, Rh and W as central metals have been synthesised and characterised. Structural investigations by X-ray single crystal crystallography supported the high degree of π-conjugation in the dithienophosphole ligands. This essential requirement for potential applications in molecular electronics and optoelectronics provides small band gaps for the materials. Investigations toward the optoelectronic properties of the respective complexes by fluorescence spectroscopy indicated that systematic alterations of the electronic structure are connected to different variables such as transition metal employed, functionalisation of the dithienophosphole ligands as well as complex geometries. The investigated Pt-based complexes exhibit only poor photoluminescence whereas Rh-, W- and Fe-based species with silyl functionalised dithienophosphole ligands show appreciable photophysical properties. The Au complexes investigated exhibit strong photoluminescence properties with very intriguing features in terms of excitation and emission wavelengths, intensity as well as selectivity. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b509277a

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PAPER
www.rsc.org/dalton | Dalton Transactions
Synthesis and optoelectronic properties of transition metal complexes
incorporating dithieno[3,2-b:2ꢀ,3ꢀ-d]phosphole ligands
Yvonne Dienes, Matthias Eggenstein, Toni Neumann, Ulli Englert and Thomas Baumgartner*
Received 1st July 2005, Accepted 17th November 2005
First published as an Advance Article on the web 9th December 2005
DOI: 10.1039/b509277a
A series of dithieno[3,2-b:2ꢀ,3ꢀ-d]phosphole-based transition metal complexes, including Au, Fe, Pt, Rh
and W as central metals have been synthesised and characterised. Structural investigations by X-ray
single crystal crystallography supported the high degree of p-conjugation in the dithienophosphole
ligands. This essential requirement for potential applications in molecular electronics and
optoelectronics provides small band gaps for the materials. Investigations toward the optoelectronic
properties of the respective complexes by fluorescence spectroscopy indicated that systematic
alterations of the electronic structure are connected to different variables such as transition metal
employed, functionalisation of the dithienophosphole ligands as well as complex geometries. The
investigated Pt-based complexes exhibit only poor photoluminescence whereas Rh-, W- and Fe-based
species with silyl functionalised dithienophosphole ligands show appreciable photophysical properties.
The Au complexes investigated exhibit strong photoluminescence properties with very intriguing
features in terms of excitation and emission wavelengths, intensity as well as selectivity.
explore the suitability of a metal functionalisation for the fine
tuning of the optoelectronic properties of the dithienophosphole
system which could then potentially be applied in functional
Introduction
The incorporation of phosphorus centres into functional p-
conjugated as well as polymeric materials is an area of growing
materials.
interest.1 The versatile reactivity and electronic nature of trivalent
phosphorus offers interesting opportunities for the development
Results and discussion
of new materials with unusual properties.2 Its ability to react
with oxidizing agents, its Lewis basicity which allows reactions
with Lewis acids in addition to the potential for coordination to
transition metals, offers a broad variety for tuning the electronic
properties of phosphorus based materials by synthetically facile
modifications that are not possible in this simplicity with genuine
organic systems.3 In the context of an implementation into p-
conjugated systems, phosphole-moieties are of particular interest
since they exhibit a reduced orbital interaction of the phosphorus
lone-pair with the conjugated p-system resulting in a low degree of
lone-pair delocalization.4–7 However, a weak interaction that is ob-
served between the p*-LUMO and the exocyclic r*PC orbital, leads
to an extraordinary electronic structure of the system with a low
lying LUMO level that can be utilised in molecular electronics.1f ,6d
We have recently established the reactivity and optoelectronic
properties of the novel dithieno[3,2-b:2ꢀ,3ꢀ-d]phosphole system
and corresponding polymeric materials displaying very advan-
tageous photophysical properties with respect to wavelength,
intensity and tunability.8 In the context of our work we were able to
show that simple chemical modifications carried out at the central
phosphorus atom such as oxidation or complexation with Lewis
acids afford dithienophosphole species with significantly altered
optoelectronic properties. In this paper we now describe the syn-
thesis and optoelectronic properties of a variety of transition metal
complexes that display dithieno[3,2-b:2ꢀ,3ꢀ-d]phosphole ligands to
Synthesis of the complexes
With the utility in optoelectronic molecular or polymeric materials
in mind, we targeted transition metal complexes of dithienophos-
pholes that are conveniently accessible via simple chemical modi-
fications and afford the metal functionalised systems in high,
desirably quantitative, yields. We therefore focused on transition
metals that are known to form strong bonds with phosphane
ligands and complexes that are fairly persistent under aerobic
conditions.
To compare the influence of different complex configura-
tions on the optoelectronic properties of our materials we first
synthesised a series square planar Pt based dithienophosphole
complexes that were expected to exhibit cis-configuration as
observed for bis(dibenzophosphole)platinum(II) halides.9 A re-
lated Pd based dithienophosphole complex ([A]2PdCl28a) shows
trans-configuration in the solid state allowing for a convenient
investigation of the differences between configuration isomers. The
platinum complexes 1A, 1B and 1C are accessible by reaction of
K2PtCl4 with two equivalents of the corresponding dithienophos-
phole A, B or C in dichloromethane at room temperature in almost
quantitative yields (Scheme 1). Compared to the free ligands (A:
d31P = −25.0;8a B: d31P = −27.4;8a C: d31P = −21.58b), their 31P
NMR spectra show single resonances that are slightly shifted
downfield upon complexation (1A: d = −9.2; 1B: d = −10.5;
1C: d = −7.6) and exhibit the typical satellites due to the presence
of Pt (1A: J(P,195Pt) = 3508 Hz; 1B: J(P,195Pt) = 3511 Hz; 1C:
J(P,195Pt) = 3506 Hz). According to the P,195Pt-coupling constants
Institut fu¨r Anorganische Chemie, RWTH-Aachen, Landoltweg 1, 52074,
Aachen, Germany. E-mail: thomas.baumgartner@ac.rwth-aachen.de;
Fax: +49 241-8092644; Tel: +49 241-8099684
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Scheme 1
only cis-configured isomers are generated.10 This is in contrast to
the observations made with the related Pd-complex where both
configuration isomers (ratio trans : cis = 3 : 1) were observed in
solution,8a which can be attributed to the lower kinetic stability
expected planar geometry of the rigid tricyclic dithienophosphole,
displaying an anti-configuration of the two thiophene moieties and
the phosphole unit. The high degree of p-conjugation, apparent in
the short C–C-single bonds and the elongated C–C-double bonds
of the fused ring systems of the ligand (see Fig. 1), as well as
1
of Pd-phosphane complexes. The H and 13C NMR data relate
8a
to those of the Pd-complex [A]2PdCl2 with a pseudo triplet
the transoid anti-arrangement of the tBuSiMe2 groups are similar
splitting for most of the 13C NMR resonances due to the coupling
to the two different phosphorus centres located at the same and
the adjacent dithienophosphole ligand. Although we were able to
obtain suitable single crystals for X-ray structure studies of the Pt
complexes from different solvents (toluene, xylenes, acetonitrile),
no satisfying structure determination could be achieved due to
some significant disorder as well as the presence of a variable
amount of strongly disordered solvent molecules within the unit
cell. The cis-configuration of the complexes, however, which is
most likely the reason for the unfavourable packing in the solid
state, was undoubtedly confirmed by these investigations.
to the related dithienophosphole oxide [B] O. The Au centre
8a
=
shows an almost linear coordination (P1–Au1–Cl1 177.26(4)◦)
˚
˚
withbondlengths of 2.2249(12) A for Au1–P1and2.2946(12)A for
Au1–Cl1 that are typical for (phosphanyl)gold(I) chlorides.12 No
aurophilic interactions are observed in the solid state (closest Au–
13
˚
Au distance ca. 5.639 A) but intermolecular interactions can be
noticed between the gold centre and some hydrogen atoms located
˚
at a thiophene unit (distance ca. 3.156 A) as well as the phenyl
˚
substituents (distances ca. 2.949 and 2.911 A) of neighbouring
molecules.
Since (phosphanyl)gold(I) complexes often have been found
to exhibit interesting luminescence properties11 that can be used
in e.g. organic light-emitting diodes (OLEDs), as shown by
Re´au and co-workers,6c,d we also synthesised dithienophosphole-
based Au(I) chloride complexes. Starting from the two differently
functionalised dithienophospholes A and B,8a complexes 2A and
2B were obtained in a quantitative reaction with (tht)AuCl in
CH2Cl2 in very good isolated yields. The 31P NMR spectra of both
complexes again show low field shifted NMR resonances at d31P =
1.9 for 2A and d31P = 2.1 for 2B confirming the complexation of
the phosphorus centre. The 1H and 13C NMR data relate to those
observed for the free ligands8a with the exception that the 1H NMR
signals of the phenyl substituent are shifted downfield which is
indicative of the metal functionalisation. These data support the,
compared with the free ligands, significantly increased acceptor
character of the central phosphorus atom affording a decrease
of the energy of the dithienophosphole p*-LUMO8a and thus
optimising the electronic structure of the system. We were able to
obtain suitable single crystals for an X-ray structure determination
of 2B from a concentrated pentane solution kept at 4 ◦C. The
Fig. 1 Molecular structure of 2B in the solid◦state (50% probability
˚
level). Selected bond lengths (A) and angles ( ): Au1–P1 2.2249(12),
Au1–Cl1 2.2946(12), P1–C3 1.814(4), P1–C6 1.803(4), P1–C11 1.814(4),
C1–C2 1.370(6), C2–C3 1.412(6), C3–C4 1.378(6), C4–C5 1.460(6),
C5–C6 1.382(6), C6–C7 1.433(6), C7–C8 1.373(6); P1–Au1–Cl1 177.26(4),
C6–P1–C3 91.6(2).
molecular structure of 2B in the solid state is related to that
8a
=
of the corresponding dithienophosphole oxide [B] O with the
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With a potential utility as catalyst system for future investiga-
tions in mind, we synthesised the corresponding rhodium com-
plexes based on the dithienophosphole system. The Rh(cod)Cl-
functionalised dithienophospholes are accessible in a quantitative
reaction of the corresponding dithienophospholes A and B8a with
half an equivalent of [Rh(cod)Cl]2 in thf at room temperature to
afford the desired rhodium complexes in good isolated yields. The
31P NMR chemical resonances of 3A and 3B show a stronger
lowfield shift compared to the Pt- and Au-complexes with d31P =
11.5 for 3A and d31P = 10.5 for 3B and exhibit the significant
doublet splitting (J(P,Rh) = 148.3 Hz for both compounds).14
Fe2(CO)9 in thf at room temperature. The 31P NMR resonance
of 5A shows the most significant low field shift of all the herein
presented complexes at d31P = 49.9.
Suitable single crystals for an X-ray structure determination
(Table 1) of the tungsten complex 4A were obtained from a
concentrated toluene solution kept at −30 ◦C. The molecular
structure of 4A in the solid state shows an octahedral complex
geometry with the W(CO)5-fragment capping the phosphorus
centre, as expected (Fig. 2). The bond lengths of the coor-
dinated dithienophosphole ligand correspond to those of the
related gold complex 2B (Table 1) and other structurally known
1
The H and 13C NMR data relate to those of the Au-complexes
2A and 2B. The presence of four distinct resonances for the
coordinated cyclooctadiene ligand, furthermore supports a square
planar complex geometry in solution, as expected.14
To further explore the effects of different complex geometries
and varying numbers of dithienophosphole ligands on the op-
toelectronic properties, we synthesised a series of tungsten and
iron carbonyl complexes exhibiting one or two dithienophosphole
ligands, respectively. W(CO)6 and Fe(CO)5 were chosen since
they provide different complex geometries (octahedral vs. trigonal
bipyramidal) that were expected to afford different configurations
for the corresponding disubstituted bis(dithienophosphole) com-
plexes. The tungsten-based mono(dithienophosphole) complexes
4A and 4C were accessible in an almost quantitative reaction of
the respective dithienophospholes A8a and C8b with W(CO)5·thf at
room temperature in thf and could be isolated in decent yields. The
31P NMR spectra of 4A and 4C show lowfield shifted resonances at
d31P = −7.9 for 4A and d31P = −3.9 for 4C, that are similar to the
Pt-based complexes supporting the increased acceptor character
Fig. 2 Molecular structure of 4A in the solid state (50% probability level).
1
of the phosphorus centre. The J(P,183W) coupling constants of
One toluene sol◦vent molecule is omitted for clarity. Selected bond lengths
227.9 Hz for 4A and 230.0 Hz for 4C also confirm the complexation
˚
(A) and angles ( ): W1–P1 2.5028(5), W1–C45 2.009(2), W1–C41 2.043(2),
1
of the phosphorus centre by a tungsten atom.15 The H and 13C
W1–C42 2.037(2), W1–C43 2.053(2), W1–C44 2.053(2), P1–C3 1.824(2),
P1–C6 1.819(2), P1–C31 1.826(2), C1–C2 1.375(3), C2–C3 1.420(3),
C3–C4 1.377(3), C4–C5 1.452(3), C5–C6 1.383(3), C6–C7 1.414(3), C7–C8
1.373(3); P1–W1–C45 175.80(6), C6–P1–C3 90.14(10).
NMR data again relate to the other complexes presented in this
paper. The same is true for the mono(dithienophosphole)iron
carbonyl complex 5A that is accessible by reaction of A with
Table 1 Crystallographic data for 2B, 4A and 6C
Compound
2B
4A
6C
Formula
Mr
C26H37AuClPS2Si2
733.24
110(2)
Monoclinic
P21/c (no. 14)
16.279(3)
13.492(3)
14.313(3)
90
91.33(3)
C25H25O5PSSi2W·C7H8
786.65
110(2)
C32H18O4P2S4W
840.49
110(2)
T/K
Crystal system
Space group
Triclinic
Triclinic
¯
¯
P1 (no. 2)
P1 (no. 2)
˚
a/A
11.1535(4)
11.5231(4)
14.0934(6)
85.359(1)
67.820(1)
72.751(1)
1600.87(11)
2, 1.632
778
3.898
2.06–30.05
28162/9031 (0.0292)
9031/15/378
R1 = 0.0220, wR2 = 0.0519
R1 = 0.0236, wR2 = 0.0525
1.069
11.179(2)
14.844(3)
18.518(4)
94.93(3)
95.76(3)
94.64(3)
3033.7(10)
4, 1.840
˚
b/A
˚
c/A
a/◦
b/◦
c /◦
90
3
˚
V/A
3142.7(11)
4, 1.550
1456
Z, Dc/Mg cm−3
F(000)
1640
4.227
l(Mo-Ka)/mm−1
5.040
h Range for data collection/◦
Reflections collected/unique (Rint
Data/restraints/parameters
Final R indices [I > 2r(I)]
R indices (all data)
1.25–28.02
25336/7583 (0.0427)
7583/0/298
R1 = 0.0338, wR2 = 0.0750
R1 = 0.0415, wR2 = 0.0876
1.167
1.11 to 28.47
47437/15170 (0.0481)
15170/0/775
R1 = 0.0310, wR2 = 0.0781
R1 = 0.0368, wR2 = 0.0811
1.048
)
GOF on F2
−3
˚
Largest diff. peak and hole/e A
1.473 and −1.376
1.461 and −0.789
3.047 and −1.908
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dithienophospholes8 with a significant degree of p-conjugation
(long C–C-double and shortened C–C-single bonds). The P–C
kind of endo/exo complex conformation, the second molecule
in the unit cell exhibits an almost coplanar arrangement of the
two dithienophosphole planes with an exo/exo conformation (see
Fig. 3). The C–C-bond lengths of the coordinated ligands support
their high degree of p-conjugation.8 The endocyclic P–C bonds of
˚
˚
bonds lengths of 1.819(2) A (P1–C6), 1.824(2) A (P1–C3) and
˚
1.826(2) A (P1–C31) are slightly longer than the ones observed for
2B indicating a reduced electron affinity of the W(CO)5 group
compared to the AuCl fragment in 2B. The W1–P1 bond of
˚
the ligands (1.814(3)–1.827(3) A) are only slightly shorter than
˚
˚
2.5028(5) A can be related to other structurally known tungsten–
the respective exocyclic P–C(phenyl) bonds (1.826(3)–1.830(3) A)
phosphole complexes1f ,6a and the W1–C45 bond of 2.009(2) A
a feature that is also observed with the free ligand C.8b Due to
the complexation to W, these bonds experience some shortening
and relate to those observed for 4A. The same is true for the W–
P bonds of the endo/exo-complex conformer (W1–P1 2.4995(10)
˚
(trans-CO) supports, compared with a carbonyl ligand-, a reduced
p-acceptor character of the dithienophosphole (see e.g. W1–C41
˚
2.043(2) A (cis-CO)).
˚
˚
Introduction of a second dithienophosphole ligand can be
achieved upon irradiation with UV-light of either the mono-
substituted tungsten pentacarbonyl complex 4C in the presence of
another equivalent of C or a mixture of two equivalents of A with
one equivalent of Fe2(CO)9 to afford the bis(dithienophosphole)
complexes 6C and 7A in good yields (Scheme 2). Compared with
their mono-substituted congeners, the 31P NMR spectra show
slightly lowfield shifted resonances at d31P = −2.9; J(P,183W) =
225.0 Hz for 6C (cf. d31P = −3.9; J(P,183W) = 230.0 Hz for 4C)
and at d31P = 59.4 for 7A (cf. d31P = 49.9 for 5A). The presence
A, W1–P2 2.5006(11) A) whereas is the exo/exo-conformer their
shortening is significantly more pronounced (W2–P3 2.4707(10)
˚
˚
A, W2–P4 2.4760(11) A) which is most likely a result of the p-
stacking mode of the two dithienophosphole ligands. As observed
for 4A, the bond lengths of trans-carbonyl groups (W–C ca. 1.99(1)
˚
A) are also significantly shorter than the W–cis-CO bonds lengths
˚
of about 2.04(1) A again supporting the reduced p-acceptor
character of the dithienophosphole ligand.
Optoelectronic properties of the complexes
of two resonance signals for the carbonyl carbon atoms in the 13
C
NMR spectrum of 6C at d13C = 202.9 and 200.7 supports a cis-
configuration of the two dithienophosphole ligands whereas the
existence of only one carbonyl resonance at d13C = 212.7 for 7A
indicates a trans-configuration for the iron complex. The pseudo
triplet splitting of most of the 13C NMR signals of 6C and 7A is
similar to those observed for the Pd-8a and Pt-complexes 1A–C and
corroborates the generation of bis(dithienophosphole) complexes.
The photoluminescence of the dithienophosphole system opens
up a great potential for applications in materials science and
optoelectronics since the detection of fluorescence is a convenient
analytical tool due to its highly sensitive, selective and safe nature.
It allows, for example, the observation electronic transitions in
progress;16,17 a change of the electronic structure of the materials
should have an effect on their luminescence properties and thus
reflecting its delocalisation and polarisation.18 Therefore, the
functionalisation of optoelectronic materials by transition metals
or their complexes, respectively, is an intriguing approach which
can be conveniently achieved by means of trivalent phosphorus
species, as already indicated.
Our investigations towards the influence of different tran-
sition metal moieties on the optoelectronic properties of the
dithienophosphole system indicate that the systematic alteration
of the electronic structure by this method is connected to a
number of variables and not always predictable. It should be
mentioned in this context that the fluorescence spectra (excitation
and emission) of the presented dithienophosphole transition
metal complexes are governed by intra-ligand p–p*-transitions.
This is in coherence with the spectra of the free ligands A–C
and their non-transition metal functionalised congeners.8 The
transition metal complex species presented herein should therefore
rather be described as transition metal-doped dithienophospholes.
However, the electronic structure of the dithienophospholes used,
the transition metals employed as well as the complex geometries
play an important role for the resulting optoelectronic absorption
and emission properties of the materials in terms of intensity. The
corresponding maximum wavelengths, particularly for emission,
onthe other hand, donot seem tobe affectedbydifferent transition
metal moieties and complex geometries as much. Most of the
complexes based on the ligands A and B presented in this paper
show a maximum wavelength of their emission at 460/461 nm,
whereas the systems based on the ligand C show a wider range
of emission wavelengths between 437 and 451 nm (see Table 2).
This red-shift of about 10–20 nm of the silyl functionalised
dithienophosphole complexes is similar to the free ligands A
Scheme 2
We were able to obtain yellow single crystals of 6C from a
concentrated pentane–toluene (1 : 1) solution at −30 ◦C that
were suitable for an X-ray structure determination. The molecular
structure of 6C (Table 1) in the solid state shows two independent,
cis-configured, octahedral complex molecules in the unit cell
whose geometry is governed by different intramolecular p-stacking
interactions between the two dithienophosphole ligands. Whereas
in one of the independent complex molecules the p-stacking is
observed between the anellated dithienophosphole ring system
and the phenyl group of the adjacent ligand, leading to a
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◦
˚
Fig. 3 Molecular structure of 6C in the solid state (50% probability level). Selected bond lengths (A) and angles ( ): endo/exo-conformer: W1–P1
2.4995(10), W1–P2 2.5006(11), W1–C3 1.986(4), W1–C4 1.999(3), W1–C1 2.042(3), W1–C2 2.045(3), P1–C13 1.825(3), P1–C17 1.814(3), P1–C101
1.833(3), P2–C23 1.819(3), P2–C26 1.811(3), P2–C201 1.826(3), C11–C12 1.356(5), C12–C13 1.417(4), C13–C14 1.374(4), C14–C15 1.457(4), C15–C17
1.375(4), C17–C16 1.420(4), C16–C18 1.353(4), C21–C22 1.356(5), C22–C23 1.422(5), C23–C24 1.372(5), C24–C25 1.449(5), C25–C26 1.372(5), C26–C27
1.425(5), C27–C28 1.374(5); P1–W1–C4 177.85(9), P2–W1–C3 172.46(10); exo/exo-conformer: W2–P3 2.4760(101), W2–P4 2.4707(10), W2–C7 1.994(4),
W2–C8 2.014(4), W2–C5 2.044(3), W2–C6 2.040(3), P3–C33 1.819(3), P3–C36 1.820(3), P3–C301 1.830(3), P4–C43 1.822(3), P4–C46 1.827(3), P4–C401
1.830(3), C31–C32 1.364(5), C32–C33 1.418(4), C33–C34 1.382(4), C34–C35 1.448(4), C35–C36 1.378(4), C36–C37 1.411(4), C37–C38 1.365(5), C41–C42
1.353(5), C42–C43 1.427(4), C43–C44 1.374(4), C44–C45 1.441(4), C45–C46 1.374(4), C46–C47 1.415(4), C47–C48 1.365(4); P3–W2–C7 179.97(12),
P4–W2–C8 179.11(10).
Table 2 Fluorescence spectroscopy data, solutions in CH2Cl2
character of the phosphorus centre and the coherent decrease of
the energy of the p*-LUMO of the dithienophospholes.8a This
strong red-shift for the absorption (ca. 20–50 nm) as well as
the emission (ca. 25–40 nm) of all complexes presented herein,
clearly rules out the existence of the free ligands in solution
being responsible for the observed luminescence properties (see
Fig. 4). The latter is further supported by the disappearance of the
d
Compound
Rel. intensitya
kexb/nm
kemc/nm
φPL
A8a
B8a
High
High
High
Very low
Low
344
364
338
365
364
362
290, 375
311, 406
370 (sh), 414
398
396
391
355
388
351
394
422
422
415
460
460
451
445
445
445
461
461
460
437
460
441
461
0.604
0.794
0.779
—
C8b
1A
1B
—
—
1C
Low
2A
Very high
Very high
Very high
High
0.556
—
2B
2B (solid)
3A
—
0.565
0.662
0.738
—
0.750
—
3B
High
4A
Medium
Very low
Medium
Very low
Medium
4C
5A
6C
7A
0.603
b
a For excitation and emission; similar experimental conditions. kmax for
excitation. c kmax for emission. d Photoluminescence quantum yield, relative
to quinine sulfate (0.1 M H2SO4 solution) 10%; excitation at 365 nm (see
ref. 24).
(kem = 422 nm), B (kem = 422 nm) and C (kem = 415 nm)
and their oxidised relatives.8 Complexation via the transition
metal units, however, leads to a significant red-shift for absorption
and emission that correlates well with the increased acceptor
Fig. 4 Normalised fluorescence spectra (excitation left, emission right)
of A (—), 5A (· · ·) and 7A (---).
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n–p*-transition band around 290 nm in most of the complexes,
which would be observed for the free ligands.19
Unfortunately, the use of the non-silyl ligand C in general
affords transition metal functionalised materials with very poor
photoluminescence properties. The same holds true for all cis-
configured Pt-complexes whose excitation and emission (1A,
1B: kem = 460 nm; 1C: kem = 451 nm) intensities are almost
negligible. This is again in contrast to the trans-configured Pd-
complex [A]2PdCl2 that shows a strong photoluminescence with
an emission at 470 nm when excited at its maximum wavelength for
absorption (384 nm).8a The latter indicates the significant influence
of the complex geometry on the optoelectronic properties of the
materials favouring the trans-configuration.
The appreciable photoluminescence properties of the rhodium
(3A,B), tungsten (4A) and iron (5A, 7A) complexes based on the
silyl functionalised dithienophospholes A and B, are surprisingly
similar with respect to their maximum wavelengths of absorption
and emission, and almost irrespective of the nature of the
transition metal, the number of dithienophosphole ligands present
and varying complex geometries. The complexes 3A,B, 4A, and
5A, 7A all show a maximum wavelength for their absorption
at around 393
5 nm with a maximum wavelength for their
emission at 460/461 nm, both strongly red-shifted from the free
ligands A and B, accompanied by the disappearance of the n–p*-
transition. Noteworthy differences in the spectra of the complexes,
obtained under the same experimental conditions, can only be
found in the relative intensities of their excitation and emission,
with the rhodium-based systems 3A,B exhibiting the strongest
photoluminescence.
The gold functionalised dithienophospholes 2A and 2B, on the
other hand, show very intriguing optoelectronic properties with
very high photoluminescence intensities, and unique wavelengths
for absorption and emission indicating highly beneficial optoelec-
tronic properties for the dithienophosphole moiety introduced
by the AuCl-fragment. Although both gold complexes 2A and
2B show similar emission spectra with emissions at 445 nm,
their excitation spectra differ significantly, suggesting a poten-
tial influence of the different substitution patterns of the silyl
functionalities of the ligands. In contrast to the other species
presented herein, 2A and 2B exhibit two significant transitions in
their respective excitation spectra (see Fig. 5). The bathochromic
transitions (2A: 375 nm; 2B: 405 nm) can be attributed to intra-
ligand p–p*-transitions,8 whereas the hypsochromic transitions at
higher energies (2A: 290 nm; 2B: 311 nm) cannot be assigned
undoubtedly.19 As discussed in the literature for related gold(I)
complexes, two possibilities can be considered: an intra-ligand
n–p*-transition or a ligand to metal charge transfer process
(LMCT).11,13 When excited at 311 nm, 2B also shows an emission
at 445 nm, similar to the excitation at 406 nm (Fig. 5, middle). This
feature would support the intra-ligand n–p*-transition process
being responsible for the blue shifted excitation band. The
excitation spectrum of 2B, however, is particularly interesting since
both transitions, that are fairly narrow, are surprisingly distinct, a
feature that is not commonly observed with the dithienophosphole
system.8 This observation suggests very selective optoelectronic
properties of 2B in contrast to 2A whose excitation spectrum
represents a typical example for dithienophospholes (Fig. 5, top).
Here, the transitions appear broader, decreasing to some extend
the selectivity, allowing for an excitation over a broader range.
Fig. 5 Fluorescence spectra (excitation left, emission right) of 2A in
solution, 2B in solution and 2B in the solid state.
The shifts of the absorption wavelengths for the n–p*-/LMCT-
(Dk = 21 nm) and the p–p*-transitions (Dk = 31 nm) between 2A
and 2B could arise from intramolecular interactions of the gold
complexes in solution that should be reduced by the sterically
demanding tert-butyldimethylsilyl-groups in 2B, apparent in the
very narrow transitions. The photoluminescence of 2B in the solid
state is also extremely intense and the fluorescence spectrum also
shows a maximum wavelength for emission at 445 nm, indicating
that 2B does not seem to aggregate in the solid state either (Fig. 5,
bottom). The excitation spectrum, on the other hand, shows a
significantly red shifted n–p*-/LMCT-transition at 370 nm now
appearing as a shoulder and a slightly shifted p–p*-transition at
414 nm. These investigations underline the intriguing properties
of gold(I) functionalised dithienophospholes and indicate that the
selectivity of the optoelectronic properties of the system could be
significantly controlled by variation of the silyl functionality.
This journal is
The Royal Society of Chemistry 2006
Dalton Trans., 2006, 1424–1433 | 1429
©

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Concluding remarks
filtered off, all volatiles removed under vacuum and the residue
was taken up in pentane (ca. 30 mL) and filtered over neutral
alumina. Evaporation of the solvent provided the products as light
yellow solids (1A: 1.04 g, 95% yield, 1B: 1.23 g, 97% yield, 1C:
0.78 g, 96% yield). Recrystallisation from aromatic hydrocarbons
or acetonitrile, respectively, at room temperature provided yellow
single crystals for all compounds.
In conclusion we have synthesised a series of different transition
metal complexes incorporating dithieno[3,2-b:2ꢀ,3ꢀ-d]phosphole
ligands that are accessible in high yields by chemically facile proce-
dures. The Au- and the two W-complexes that were characterised
by X-ray single crystal crystallography exhibit a high degree of
p-conjugation present in the dithienophosphole ligand systems.
This feature supports the potential utility of transition metal
functionalised dithienophospholes for molecular electronics. The
experimental data further indicate that the transition metal frag-
ments increase the electron acceptor character of the phosphorus
centre for the p-conjugated system. As a result, the energy of the
p*-LUMO of the dithienophosphole unit is significantly lowered8
ultimately leading to materials with smaller band gaps compared
with the free ligands.
The optoelectronic properties of the complexes investigated, on
the other hand, indicate that a proper choice of transition metals
and respective geometries as well as suitable dithienophospholes
are necessary to obtain materials with extraordinary photophys-
ical properties that are potentially applicable in optoelectronics.
Although the rhodium (3A,B), tungsten (4A) and iron (5A,
7A) complexes based on the silyl functionalised dithienophos-
pholes A and B show appreciable photoluminescence, only the
functionalisation via AuCl affords a significant optimisation of
the optoelectronic properties of the dithienophosphole moiety.
This strategy, however, produces highly selective materials with
improved photoluminescence properties, particularly in the case
of 2B, that have not been observed before with the dithienophos-
phole system. This functionalisation of the dithieno[3,2-b:2ꢀ,3ꢀ-
d]phosphole moiety will therefore play a major role in our future
investigations towards the generation of dithienophosphole-based
functional materials and devices.
1A. 31P{ H} NMR (202.6 MHz, CDCl3): d −9.2 (d, J(P,Pt)
1
1
1
3
3511 Hz); H NMR (500 MHz, CDCl3): d 7.67 (dd br, J(H,P)
3
3
13.7 Hz, J(H,H) 7.6 Hz, 4H, o-Ph), 7.40 (t br, J(H,H) 7.5 Hz,
2H, p-Ph), 7.28 (t br, 3J(H,H) 7.6 Hz, 4H, m-Ph), 6.66 (br, 4H, Ar),
0.26 ppm (s, 36H; Si(CH3)3); 13C{ H} NMR (125.0 MHz, CDCl3):
1
d 149.0 (t, J(C,P) 6.7 Hz; Ar), 144.3 (t, J(C,P) 3.8 Hz; Ar), 140.0 (d
br, 1J(C,P) 68.0 Hz; ipso-Ar), 134.6 (t, J(C,P) 5.9 Hz; o-Ar), 133.0
(t, J(C,P) 6.7 Hz; o-Ar), 131.4 (s, p-Ph), 128.7 (t, J(C,P) 5.9 Hz;
1
m-Ar), 128.6 (d, J(C,P) 101.6 Hz; ipso-Ph), −0.1 ppm (s; SiC3).
Calc. for C40H50Cl2P2PtS4Si4 (1097.04): C, 43.70; H, 4.58; S, 11.67.
Found: C, 43.65; H, 4.48; S, 11.63%.
1
1
1B. 31P{ H} NMR (202.6 MHz, CDCl3): d −10.5 (d, J(P,Pt)
1
3
3508 Hz); H NMR (500 MHz, CDCl3): d 7.70 (dd br, J(H,P)
3
3
14.3 Hz, J(H,H) 7.6 Hz, 4H, o-Ph), 7.39 (t br, J(H,H) 7.5 Hz,
2H, p-Ph), 7.27 (t br, J(H,H) 7.6 Hz, 4H, m-Ph), 6.69 (br, 4H,
3
Ar), 0.83 (s, 36H, SiC(CH3)3), 0.20 (s, 12H, Si(CH3)2), 0.18 (s,
1
12H, Si(CH3)2); 13C{ H} NMR (125.0 MHz, CDCl3): d 149.1 (t,
J(C,P) 6.9 Hz; Ar), 141.3 (t, J(C,P) 5.2 Hz; Ar), 140.5 (d br, 1J(C,P)
69.4 Hz; ipso-Ar), 135.9 (t, J(C,P) 7.2 Hz; o-Ar), 133.2 (t, J(C,P)
6.2 Hz; o-Ar), 131.6 (s, p-Ph), 128.7 (t, J(C,P) 5.9 Hz; m-Ar),
128.6 (d, 1J(C,P) 101.5 Hz; ipso-Ph), 26.3 (s; SiC(CH3)3), 16.9 (s;
SiC(CH3)3), −4.9 ppm (s; SiMe2), −5.0 ppm (s; SiMe2). Calc. for
C52H74Cl2P2PtS4Si4 (1265.23): C, 49.27; H, 5.88; S, 10.12. Found:
C, 49.03; H, 5.87; S, 10.21%.
1
1C. 31P{ H} NMR (80.9 MHz, CD2Cl2): d −7.6 (d, 1J(P,Pt) =
1
3
3506 Hz); H NMR (500 MHz, CD2Cl2): d 7.53 (dd br, J(H,P)
3
3
12.5 Hz, J(H,H) 7.8 Hz, 4H, o-Ph), 7.40 (t br, J(H,H) 7.8 Hz,
Experimental
3
2H, p-Ph), 7.30 (m br, J(H,H) 7.8 Hz, 4H, m-Ph), 7.20 (dd br,
3J(H,H) 5.0 Hz, J(H,P) 2.6 Hz, 4H, Ar–H), 6.77 (d br, J(H,P)
4
3
General considerations
5.0 Hz, 4H, Ar–H); 13C{ H} NMR (125.0 MHz, CD2Cl2): d 148.7
1
(pt, 1,3J(C,P) 8.9 Hz, ipso-Ar), 144.9 (pt, 2J(C,P) 5.5 Hz, Ar), 137.7
(d br, 1J(C,P) 49.9 Hz, ipso-Ph), 132.6 (pt, 2/4J(C,P) 5.6 Hz, o-Ar),
131.8 (s br, p-Ph), 129.0 (pt, 3/5J(C,P) 6.7 Hz, m-Ar), 128.3 (pt,
3/5J(C,P) 6.7 Hz, m-Ar), 127.8 (pt, 2/4J(C,P) 6.7 Hz, o-Ar). Calc.
All manipulations were carried out in dry glassware and under
inert atmosphere of purified argon using Schlenk techniques.
Solvents were dried over appropriate drying agents and then
distilled. K2PtCl4, W(CO)6 and Fe2(CO)9 were used as received.
(tht)AuCl,20 [Rh(cod)Cl]221 as well as the dithienophospholes A,8a
B8a and C8b were prepared by literature methods. W(CO)5·thf
1
2
for C28H18Cl2P2PtS4· CH2Cl2 (853.10): C, 40.12; H, 2.24; S, 15.03.
Found: C, 40.29; H, 2.33; S, 14.92%.
1
was generated photochemically from W(CO)6 in thf. H NMR,
Synthesis of [A]AuCl (2A) and [B]AuCl (2B). A solution of
the respective dithienophosphole (A: 0.42 g, 1 mmol, B: 0.48 g,
1 mmol) in dichloromethane (20 mL) was treated with (tht)AuCl
(0.32 g, 1 mmol), dissolved in CH2Cl2 (5 mL) and stirred for 1 h at
room temperature. Subsequently, all volatiles were removed under
vacuum and the residue was taken up in pentane (ca. 10 mL). The
gold complexes 2A and 2B were obtained as colourless or light
yellow crystals from concentrated pentane solutions kept at 4 ◦C
(2A: 0.53 g, 90% yield, 2B: 0.62 g, 84% yield).
13C NMR, and 31P NMR spectra were recorded on a Bruker
DRX 400, Varian Mercury 200 or Unity 500 MHz-spectrometer.
Chemical shifts were referenced to external 85% H3PO4 (31P) or
1
TMS (13C, H). Electron ionization (70 eV) mass spectra were
run on a Finnigan 8230 spectrometer. IR spectra were recorded
on a Nicolet Avatar 360 FT-IR Spectrometer. Elemental analyses
were performed by the Microanalytical Laboratory of the Institut
fu¨r Anorganische und Analytische Chemie, Johannes Gutenberg-
Universita¨t, Mainz.
1
2A. 31P{ H} NMR (202.6 MHz, CDCl3): d 1.9; 1H NMR
Synthesis of [A]2PtCl2 (1A), [B]2PtCl2 (1B) and [C]2PtCl2 (1C).
A solution of the respective dithienophosphole (A: 0.42 g, 1 mmol,
B: 0.48 g, 1 mmol, C: 0.27 g, 1 mmol) in dichloromethane (20 mL)
was treated with K2PtCl4 (0.21 g, 0.5 mmol) and stirred for
24 h at room temperature. Subsequently, the generated KCl was
(500 MHz, CDCl3): d 7.62 (dd, 3J(H,P) 15.0 Hz, 3J(H,H) 7.9 Hz,
2H, o-Ph), 7.38 (tm, 3J(H,H) 7.9 Hz, 1H, p-Ph), 7.28 (td, 3J(H,H)
7.9 Hz, 4J(H,P) 3.1 Hz, 2H, m-Ph), 7.20 (d, 3J(H,P) 2.1 Hz, 2H,
1
Ar), 0.35 (s, 18H, Si(CH3)3); 13C{ H} NMR (125.0 MHz, CDCl3):
d 150.0 (d, J(C,P) 17.2 Hz, Ar), 146.2 (d, J(C,P) 9.7 Hz, Ar),
1430 | Dalton Trans., 2006, 1424–1433
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©

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139.6 (d, J(C,P) 65.5 Hz, ipso-Ar), 133.6 (d, 2J(C,P) 17.2 Hz, Ar),
132.5 (br, p-Ph), 132.4 (d, 2J(C,P) 16.1 Hz, o-Ar), 129.4 (d, 3J(C,P)
11.8 Hz, m-Ph), 126.6 (d, J(C,P) 61.2 Hz, ipso-Ph), −0.2 (s, SiC3).
Calc. for C20H25AuClPS2Si2 (648.00): C, 37.01; H, 3.88; S, 9.88.
Found: C, 36.90; H, 3.72; S, 9.71%.
Synthesis of [A]W(CO)5 (4A) and [C]W(CO)5 (4C). A solution
of the respective dithienophosphole (A: 0.83 g, 2 mmol, C: 0.52 g,
2 mmol) in THF (10 mL) was treated with W(CO)5·thf (0.87 g,
2.2 mmol) dissolved in thf (20 ml) at room temperature. The
reaction mixture was stirred for 16 h, all volatile materials were
then removed under vacuum. The light yellow or off white residue,
respectively, was taken up in hexane (ca. 10 ml). The product 4A
was obtained from a concentrated hexane–toluene (1 : 1) solution
at −30 ◦C as yellow crystals (0.76 g, 51% yield); complex 4C was
obtained from a concentrated hexane solution at −30 ◦C as off
white powder (1.07 g, 83% yield).
1
2B. 31P{ H} NMR (202.6 MHz, CDCl3): d 2.1; 1H NMR
(500 MHz, CDCl3): d 7.62 (dd, 3J(H,P) 14.3 Hz, 3J(H,H) 7.6 Hz,
2H, o-Ph), 7.38 (tm, 3J(H,H) 7.6 Hz, 1H, p-Ph), 7.28 (td, 3J(H,H)
7.6 Hz, 4J(H,P) 2.8 Hz, 2H, m-Ph), 7.20 (d, 3J(H,P) 1.5 Hz,
2H, Ar), 0.93 (s, 18H, SiC(CH3)3), 0.31 (s, 6H, Si(CH3)2), 0.30
1
(s, 6H, Si(CH3)2); 13C{ H} NMR (125.0 MHz, CDCl3): d 150.1 (d,
1
4A. 31P{ H} NMR (162.0 MHz, CDCl3): d −7.9 (1J(P,W) 227.9
J(C,P) 14.4 Hz, Ar), 143.3 (d, J(C,P) 9.6 Hz, Ar), 139.3 (d, J(C,P)
67.1 Hz, ipso-Ar), 133.5 (d, 2J(C,P) 18.2 Hz, Ar), 133.4 (d, 2J(C,P)
16.3 Hz, o-Ar), 132.5 (br, p-Ph), 129.4 (d, 3J(C,P) 13.4 Hz, m-Ph),
126.6 (d, J(C,P) 60.4 Hz, ipso-Ph), 26.3 (s; SiC(CH3)3), 16.8 (s;
SiC(CH3)3), −4.9 ppm (s; SiMe2), −5.0 ppm (s; SiMe2). Calc. for
C26H37AuClPS2Si2 (732.10): C, 42.59; H, 5.09; S, 8.75. Found: C,
42.53; H, 5.01; S, 8.68%.
Hz); 1H NMR (400 MHz, CDCl3): d 7.51 (m br, 2H, o-Ph), 7.37
(m br, 5H, Ar–H), 7.31 (m br, 2H, Ar–H), 0.32 (s, 18H, Si(CH3)3);
1
13C{ H} NMR (100.4 MHz, CDCl3): d 198.4 (d, 2J(C,P) 20.7 Hz,
2
1
1J(C,W) 406.5 Hz, trans-CO), 195.8 (d, J(C,P) 6.8 Hz, J(C,W)
137.9 Hz, cis-CO), 146.8 (d, 2J(C,P) 38.9 Hz, Ar), 146.5 (d, J(C,P)
2.9 Hz, Ar), 144.8 (d, J(C,P) 7.8 Hz, Ar), 132.7 (d, 1J(C,P) 40.2 Hz,
ipso-Ph), 132.0 (d, 2J(C,P) 15.3 Hz, o-Ar), 130.6 (d, 2J(C,P)
13.3 Hz, o-Ar), 130.3 (d, 4J(C,P) 2.0 Hz, p-Ph), 128.8 (d, 3J(C,P)
10.7 Hz, m-Ar), −0.3 (s, SiC3). IR (KBr, cm−1): 2071, 1989(sh),
1958, 1941, 1905 m(CO). MS (70 eV): m/z (relative intensity) 740
(20) [M+], 684 (30) [M+ − 2CO], 600 (130) [M+ − 5CO], 432
Synthesis of [A]Rh(cod)Cl (3A) and [B]Rh(cod)Cl (3B).
A
solution of the respective dithienophosphole (A: 0.42 g, 1 mmol,
B: 0.48 g, 1 mmol) in thf (20 mL) was treated with [Rh(cod)Cl]2
(0.25 g, 0.5 mmol) and stirred for 30 min at room temperature.
Subsequently, all volatiles were removed under vacuum and
the residue was taken up in pentane (ca. 10 mL) and filtered
over neutral alumina. The rhodium complexes 3A and 3B were
obtained as orange solids from concentrated pentane solutions
kept at −30 ◦C (3A: 0.48 g, 73% yield, 3B: 0.57 g, 77% yield).
+
+
(40) [PhPW(CO)5 ], 73 (100) [SiMe3 ]. Calc. for C25H25O5PS2Si2W
(739.99): C, 40.54; H, 3.40; S, 8.66. Found: C, 40.76; H, 3.59; S,
8.66%.
1
4C. 31P{ H} NMR (162.0 MHz, CDCl3): d −3.9 (1J(P,W) 230.0
Hz); 1H NMR (400 MHz, CDCl3): d 7.48 (m br, 2H, o-Ph), 7.36 (m
1
br, 3H, Ar–H), 7.29 (dd, J 4.8 Hz, J 0.6 Hz, 2H, Ar–H); 13C{ H}
1
1
3A. 31P{ H} NMR (202.6 MHz, CDCl3): d 11.5 (d, J(P,Rh)
1
148.3 Hz); 1H NMR (500 MHz, CDCl3): d 7.77 (dd, 3J(H,P)
11.9 Hz, J(H,H) 7.6 Hz, 2H, o-Ph), 7.39 (s, 2H, Ar), 7.34 (m,
NMR (100.4 MHz, CDCl3): d 198.0 (d, J(C,W) 21.0 Hz, trans-
CO), 195.6 (d, 2J(C,P) 6.5 Hz, 1J(C,W) 406.5 Hz, cis-CO), 144.8
3
1
1
(d, J(C,P) 47.7 Hz, ipso-Ar), 141.7 (br, Ar), 132.5 (d, J(C,P)
3H, Ph), 5.56 (br, 2H, CH of cod), 3.71 (br, 2H, CH of cod), 2.40
40.2 Hz, ipso-Ph), 130.4 (d, 2J(C,P) 13.2 Hz, o-Ar), 130.4 (d,
(d br, J 10.1 Hz, 2H CH2 of cod), 2.06 (d br, J 13.4 Hz, 2H, CH2 of
4J(C,P) 2.0 Hz, p-Ph), 128.4 (d, J(C,P) 10.7 Hz, m-Ar), 127.7
3
1
cod), 0.32 (s, 18H, Si(CH3)3); 13C{ H} NMR (125.0 MHz, CDCl3):
3
2
(d, J(C,P) 11.2 Hz, m-Ar), 130.4 (d, J(C,P) 16.7 Hz, o-Ar). IR
(KBr, cm−1): 2073, 2019, 1990, 1945, 1917 m(CO). MS (70 eV):
m/z (relative intensity) 596 (40) [M+], 540 (25) [M+ − 2CO], 512
(40) [M+ − 3CO], 456 (100) [M+ − 5CO]. Calc. for C19H9O5PS2W
(644.01): C, 38.28; H, 1.52; S, 10.76. Found: C, 38.37; H, 1.62; S,
10.88%.
d 148.0 (d, J(C,P) 13.0 Hz, Ar), 143.6 (d, J(C,P) 8.0 Hz, Ar), 142.8
(d, 1J(C,P) 44.8 Hz, ipso-Ar), 134.2 (d, 2J(C,P) 13.0 Hz, Ar), 133.5
2
1
(d, J(C,P) 14.0 Hz, o-Ar), 130.6 (d, J(C,P) 41.9 Hz, ipso-Ph),
3
130.4 (br, p-Ph), 128.6 (d, J(C,P) 11.0 Hz, m-Ph), 106.1 (dd,
1J(C,Rh) 13.0 Hz, 2J(C,P) 7.0 Hz, CH of cod), 69.6 (d, 1J(C,Rh)
13.0 Hz, CH of cod), 33.4 (s, CH2 of cod), 28.8 (s, CH2 of cod),
−0.0 (s, SiC3). Calc. for C28H37ClPRhS2Si2 (663.23): C, 50.71; H,
5.62; S, 9.67. Found: C, 50.63; H, 5.58; S, 9.71%.
Synthesis of [A]Fe(CO)4 (5A). A solution of Fe2(CO)9 (0.41 g,
1.1 mmol) in THF (30 mL) was treated with dithienophosphole A
(0.42 g, 1.0 mmol), dissolved in THF (10 mL) at room temperature
and stirred for 1 h. The volatiles were removed under vacuum and
the residue taken up in hexane (ca. 30 mL). Filtration over neutral
alumina provides 5A as red oil in 85% yield (0.50 g).
1
1
3B. 31P{ H} NMR (202.6 MHz, CDCl3): d 10.6 (d, J(P,Rh)
148.3 Hz); 1H NMR (500 MHz, CDCl3): d 7.78 (dd, 3J(H,P)
11.6 Hz, J(H,H) 7.6 Hz, 2H, o-Ph), 7.41 (s, 2H, Ar), 7.33 (m,
3
3H, Ph), 5.54 (br, 2H, CH of cod), 3.68 (br, 2H, CH of cod),
2.37 (br, 2H CH2 of cod), 2.05 (br, 2H, CH2 of cod), 0.91 (s,
18H, SiC(CH3)3), 0.31 (s, 6H, Si(CH3)2), 0.29 (s, 6H, Si(CH3)2);
1
31P{ H} NMR (162.0 MHz, CDCl3): d 49.9; 1H NMR
(400 MHz, CDCl3): d 7.62 (dd, J 12.74 Hz, J 6.74 Hz, 2H, o-
Ph), 7.38 (m br, 3H, Ar), 7.28 (br, 2H, m-Ph), 0.34 (s, 18H,
1
13C{ H} NMR (125.0 MHz, CDCl3): d 148.0 (d, J(C,P) 9.7 Hz,
Ar), 142.7 (d, 1J(C,P) 43.0 Hz, ipso-Ar), 140.6 (d, J(C,P) 6.4 Hz,
Si(CH3)3); 13C{ H} NMR (100.4 MHz, CDCl3): d 212.5 (d,
1
2
2
Ar), 135.5 (d, J(C,P) 11.8 Hz, Ar), 133.4 (d, J(C,P) 14.0 Hz,
o-Ar), 130.4 (d, 1J(C,P) 41.9 Hz, ipso-Ph), 130.3 (br, p-Ph), 128.5
(d, 3J(C,P) 10.7 Hz, m-Ph), 105.9 (dd, 1J(C,Rh) 12.9 Hz, 2J(C,P)
7.5 Hz, CH of cod), 69.7 (d, 1J(C,Rh) 12.9 Hz, CH of cod), 33.3
(s, CH2 of cod), 28.8 (s, CH2 of cod), 26.3 (s; SiC(CH3)3), 17.0 (s;
SiC(CH3)3), −4.9 ppm (s; SiMe2), −5.0 ppm (s; SiMe2). Calc. for
C34H49ClPRhS2Si2 (746.13): C, 54.64; H, 6.61; S, 8.58. Found: C,
55.00; H, 6.82; S, 8.60%.
2J(C,P) 20.2 Hz, CO), 146.7 (d, J(C,P) 11.7 Hz, Ar), 146.7 (d,
J(C,P) 52.7 Hz, ipso-Ar), 145.4 (d, J(C,P) 8.6 Hz, Ar), 131.8
(d, 2J(C,P) 14.4 Hz, Ar), 131.5 (d, 2J(C,P) 12.3 Hz, o-Ar),
131.0 (br, p-Ph), 130.8 (d, J(C,P) = 46.8 Hz, ipso-Ar), 128.7 (d,
3J(C,P) 11.2 Hz, m-Ph), −0.3 (s, SiC3). IR (KBr, cm−1): 2051,
1977, 1947, 1933 m(CO). Calc. for C24H25FeO4PS2Si2 (583.98):
C, 49.31; H, 4.31; S, 10.97. Found: C, 49.39; H, 4.29; S,
10.87%.
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Synthesis of [C]2W(CO)4 (6C). A solution of [C]W(CO)5 (4C,
0.64 g, 1 mmol) in THF (10 mL) was treated with another
equivalent of the dithienophosphole C (0.26 g, 1 mmol) dissolved
in thf (20 ml) at room temperature. The reaction mixture was then
stirred for 4 h at room temperature under irradiation with UV-
light, before all volatile materials were removed under vacuum.
Complex 6C was obtained from a hexane–toluene (1 : 1) solution
at −30 ◦C as yellow crystals (0.59 g, 67% yield).
Acknowledgements
The authors would like to thank Prof. Dr J. Okuda for his
generous support of this work. Financial support of the Fonds der
Chemischen Industrie (FCI), the Bundesministerium fu¨r Bildung
und Forschung (BMBF) and the Deutsche Forschungsgemein-
schaft (DFG) is gratefully acknowledged. We thank B. Wirges for
experimental assistance and Umicore AG & Co. KG for generous
gifts of HAuCl4 and RhCl3·xH2O.
1
31P{ H} NMR (202.6 MHz, CDCl3): d −2.4 (1J(P,W) 225.0
Hz); 1H NMR (500 MHz, CDCl3): d 7.28 (m br, 4H, o-Ph), 7.21
3
3
(m br, 6H, Ph–H), 7.09 (dd, J(H,H) 5.0 Hz, J(H,P) 2.8 Hz,
References
4H, Ar–H), 7.00 (d, 3J(H,H) 5.0 Hz, 4H, Ar–H); 13C{ H} NMR
1
2
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(100.4 MHz, CDCl3): d 202.9 (pt, J(C,P) 8.6 Hz, CO), 200.7 (t,
2J(C,P) 7.8 Hz, CO), 143.6 (dd, 1J(C,P) 43.5 Hz, 3J(C,P) 4.5 Hz,
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Synthesis of [A]2Fe(CO)3 (7A). A solution of Fe2(CO)9 (0.27 g,
0.75 mmol) in THF (25 mL) was treated with dithienophosphole A
(0.62 g, 1.5 mmol), dissolved in THF (10 mL) at room temperature
and stirred for 4 h under irradiation with UV-light. The volatiles
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pentane (ca. 40 mL). Filtration over neutral alumina provides 7A
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1
31P{ H} NMR (162.0 MHz, CDCl3): d 59.4; 1H NMR
(400 MHz, CDCl3): d 7.65 (br, 4H, o-Ph), 7.32 (m br, 10H, Ar),
1
0.30 (s, 36H, Si(CH3)3); 13C{ H} NMR (100.4 MHz, CDCl3):
2
d 212.7 (t, J(C,P) 29.7 Hz, CO), 149.0 (m, ipso-Ar), 145.9 (t,
J(C,P) 5.2 Hz, Ar), 143.8 (t, 1J(C,P) 3.4 Hz, Ar), 133.9 (m, ipso-
Ar), 132.7 (d, J(C,P) 6.9 Hz, Ar), 131.4 (t, J(C,P) 6.1 Hz, Ar),
129.8 (s, p-Ph), 128.3 (t, J(C,P) 5.2 Hz, m-Ph), −0.2 (s, SiC3).
IR (KBr, cm−1): 1905, 1884 m(CO). Calc. for C43H50FeO3P2S4Si4
(972.05): C, 53.07; H, 5.18; S, 13.18. Found: C, 53.01; H, 5.25; S,
13.28%.
X-Ray crystallography
Crystallographic data for 2B, 4A and 6C are summarised in
Table 1. For all complexes studied, data were collected on a Bruker
SMART D8 goniometer with APEX CCD detector at 110 K using
˚
Mo-Ka radiation (k = 0.71073 A, graphite monochromator).
The unit cell parameters were obtained by the least-squares
refinement of 6172 (2B), 8006 (4A) or 986 (6C) reflections,
respectively. SADABS22 method of correcting absorption was
applied in all cases. The structures were solved by direct methods
(SHELXTL)23 and refined on F2 by full-matrix least-squares
techniques. All non-hydrogen atoms were refined anisotropically.
Hydrogen atoms were placed geometrically and refined using a
riding model.
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CCDC reference numbers 276963 (4A), 276964 (2B), 276965
(6C).
For crystallographic data in CIF or other electronic format see
DOI: 10.1039/b509277a
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1432 | Dalton Trans., 2006, 1424–1433
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