Unexpected oxidative dimerisations of a cyclopentadienyl-phosphane formation of unprecedented, structurally remarkable phosphacyclic compounds

Article abstract of DOI:10.1002/ejic.200901267

The reactions of Me₂PCp^# (1) (Cp^# = C ₅HMe₄) with Ph₃PCH₂X⁺ X^-(X = Cl, Br, I) and diiodomethane as potential electrophiles have been investigated. Unexpectedly, in all four cases unprecedented oxidative dimerisations of the cyclopentadienylphosphane 1 have been observed. In the reactions with the phosphonium salts, an ionic group 15 analogue of octamethyl-tetrahydro-s-indacene with different: counterions X- has been obtained (5-7) as a result of X⁺ transfer and H⁺ elimination. In the reaction of 1 with dilodomethane a fourfold anellated, partially unsaturated, heterocyclic compound 9 exhibiting two spiro carbon centres, which are directly linked, was formed, presumably as a result of iodine radical transfer. Both of the novel phosphorus heterocycles have been characterised by means of single crystal XRD analysis.

Full text of DOI:10.1002/ejic.200901267

FULL PAPER
DOI: 10.1002/ejic.200901267
Unexpected Oxidative Dimerisations of a Cyclopentadienyl-Phosphane –
Formation of Unprecedented, Structurally Remarkable Phosphacyclic
Compounds
Crispin Lichtenberg,[a] Michael Elfferding,[a] and Jörg Sundermeyer*[a]
Keywords: Phosphorus heterocycles / Phosphanes / Spiro compounds / Isolobal relationship / Oxidative dimerisation
The reactions of Me2PCp# (1) (Cp#
=
C5HMe4) with
and H+ elimination. In the reaction of 1 with diiodomethane
a fourfold anellated, partially unsaturated, heterocyclic com-
pound 9 exhibiting two spiro carbon centres, which are di-
Ph3PCH2X+ X–(X = Cl, Br, I) and diiodomethane as potential
electrophiles have been investigated. Unexpectedly, in all
four cases unprecedented oxidative dimerisations of the cy- rectly linked, was formed, presumably as a result of iodine
clopentadienylphosphane 1 have been observed. In the reac-
tions with the phosphonium salts, an ionic group 15 analogue
of octamethyl-tetrahydro-s-indacene with different counter-
ions X– has been obtained (5–7) as a result of X+ transfer
radical transfer. Both of the novel phosphorus heterocycles
have been characterised by means of single crystal XRD
analysis.
Introduction
Constrained geometry complexes (CGCs) have been es-
tablished as a class of catalysts for olefin polymerisation,
since they were first described in the early 1990s.[1] The pro-
nounced characteristic of these catalytic systems is their
ability to incorporate higher olefins into a polymer chain.[2]
In this respect they were found to be superior to ansa-
metallocenes, which represent a closely related class of poly-
merisation catalysts. Dianions derived from cyclopentadien-
ylsilylamines are the archetypes of ligands for the synthesis
of CGCs (A, Scheme 1).[3] These are isoelectronic (and iso-
lobal) to monoanionic ligands of type B (Scheme 1), which
have therefore been in the focus of our research interest.
We recently reported a convenient synthetic approach to a
variety of P-amino-cyclopentadienylidene-phosphoranes,[4]
which are protonated forms of type B ligands, and their use
for the complexation of lanthanides.[5] The series of isoelec-
tronic ligands for the synthesis of CGCs can be extended
to monoanions C (Scheme 1). The protonated forms of type
C ligands can formally be described as cyclopentadienyl-
carbodiphosphoranes, a class of compounds which is un-
known to the literature and which we set out to synthesise.
In this paper we would like to describe an unusual unprece-
dented reaction pattern of a cyclopentadienylphosphane
which we observed during our studies concerning a possible
access to type C ligands.
Scheme 1. Three examples of isoelectronic ligands for the synthesis
of constrained geometry complexes; R = alkyl, aryl.
Results and Discussion
Formation of a 4,8-Diphospha-tetrahydro-s-indacene
Hexaphenylcarbodiphosphorane[6] is the most investi-
gated representative of the class of parent carbodiphos-
phoranes R3P–C–PR3. In analogy to a well established syn-
thetic route to this molecule[7] the reaction of a cyclopen-
tadienylphosphane with halomethyltriphenyl-phosphonium
salts (2–4) as electrophiles was studied. Unexpectedly, the
outcome of this reaction was not an overall nucleophilic
displacement of a halogen substituent by a phosphane moi-
ety (upper part, Scheme 2), but an oxidative dimerisation
of the cyclopentadienylphosphane 1 (lower part, Scheme 2)
yielding the products 5–7. The dication of the bisphosphon-
ium salts 5–7 exhibits Ci-symmetry leading to isochrony of
1
six pairs of methyl groups in the H NMR spectra and one
pair of phosphorus atoms in the 31P NMR spectra. The low
solubility of the dimers 5–7 in common solvents did not
allow for interpretable 13C NMR spectra to be obtained.
The molecular structure of the dication being part of the
substances discussed here was unambiguously established
via X-ray analysis of 7 (Figure 1). This dication is a group
[a] Fachbereich Chemie der Philipps-Universität Marburg,
Hans-Meerwein-Str., 35032 Marburg, Germany
Fax: +49-6421 2828917
E-mail: jsu@staff.uni-marburg.de
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C. Lichtenberg, M. Elfferding, J. Sundermeyer
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Scheme 2. Planned (upper part) and observed (lower part) outcome of the reaction of cyclopentadienylphosphane 1 with halomethyltri-
+
phenylphosphonium salts 2–4; PMePh3 X– was isolated in the case of X = I as a stoichiometric side product.
15 derivative of a molecule with a tetrahydro-s-indacene been described (F, Scheme 3).[8b] Being only the second ex-
core and is isolobal to the known group 14 parent com- ample of such a group 15 derivative[9] and the first one to
pound (D, Scheme 3).[8a] A group 16 derivative has also be characterised via X-ray analysis it represents the miss-
ing link between substances of type D and type F.
In the molecular structure of 7 the six-membered hetero-
cycle is found to be in a slightly distorted chair conforma-
tion. Deviations of bond angles [105.6(1)–122.0(2)°] from
an idealised six-membered carbon ring can be ascribed to
the incorporation of two heteroatoms and two sp2-hybrid-
ised carbon atoms into the cycle as well as to the anellation
of two pentacycles. These anellated cyclopentadienyl rings
are parallel, indicated by an interplanar (C5)–(C5)Ј angle
of 0.0(1)°, and exhibit two distinct double bonds. They are
essentially planar as the distance between the best plane of
four sp2 carbon atoms and the sp3 carbon atom (C3) is as
small as 0.000(3) Å. The P–C bonds in 7 range from
1.768(3) to 1.843(4) Å, which points at the differences of
the involved carbon atoms with respect to hybridisation and
Figure 1. Molecular structure of 7; the thermal ellipsoids are drawn
incorporation into a ring system. The characteristics de-
at the 50% probability level. Hydrogen atoms are omitted for clar-
scribed above are in good agreement with those found in
type D and F compounds (Scheme 3) with one exception.
This is that deviations of bond angles in the six-membered
ring from an idealised carbon hexacycle are much smaller
in the case of D as there are no heteroatoms involved.
Mechanistic aspects of the reactions leading to the for-
mation of the bisphosphonium salts 5–7, which are the
main products in all three cases, shall briefly be discussed.
Three different kinds of elementary reactions are undergone
in each of these syntheses. (i) Selectivity and yield of the
reactions increase with the atomic number of the halogen
atoms in the reactants 2–4. Having in mind that based on
the HSAB principle phosphanes represent soft bases and
the softness of halogen cations increases with their atomic
number,[10] an X+ abstraction (X = Cl, Br, I) from the halo-
methyltriphenylphosphonium salts 2–4 is a plausible initiat-
ing reaction step. Accordingly, a P-halo-cyclopentadienyl-
phosphonium salt (G, Scheme 4) and triphenylmethyl-
enephosphorane, a non charged leaving group, are formed
as intermediates. An elementary reaction of this kind
should be undergone two times per formula unit, as both
phosphorus atoms in the products 5–7 exhibit a formal oxi-
dation state of +V. When the reaction leading to product
7 (X = I) was carried out at lower temperatures, indirect
ity. Two molecules of DMSO per formula unit are present in the
crystal structure; they do not interact with 7 and are therefore not
shown. Selected bond lengths [Å], distances [Å], bond angles [°]
and dihedral angles [°]: P1–C1 1.786(3), P1–C2 1.784(3), P1–C3
1.843(4), P1–C4Ј 1.768(3), C3–C4 1.537(4), C4–C5 1.362(4), C5–
C6 1.469(4), C6–C7 1.349(4), C7–C3 1.507(3), plane(C4, C5, C6,
C7)–C3 0.000(3), C1–P1–C2 108.2(1), C1–P1–C3 108.5(1), C1–P1–
C4Ј 112.7(1), C2–P1–C3 109.2(1), C2–P1–C4Ј 112.5(1), C3–P1–C4Ј
105.6(1), P1–C3–C4 106.3(2), C3–C4–P1Ј 122.0(2), plane(C3, C4,
C5, C6, C7)–plane(C3Ј, C4Ј, C5Ј, C6Ј, C7Ј) 0.0(1).
Scheme 3. Isolobal relationship between 1,2,3,3a,5,6,7,7a-octa-
methyl-3a,4,7a,8-tetrahydro-s-indacene (D, left) and a group 15 an-
alogue (E, middle), which the molecular structures have been estab-
lished of by X-ray analyses. A group 16 analogue (F, right) has also
been characterised via X-ray analysis.
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Oxidative Dimerisations of a Cyclopentadienyl-Phosphane
spectroscopic evidence for the appearance of triphenylmeth- Evidence of Br···Br– Contacts in Ph3PCH2Br+ Br– (3)
ylenephosphorane, the plausible intermediate formed from
The abstraction of an iodine cation from the phospho-
oxidant 4 upon loss of I+ and I–, could be found (for details
nium salt 4 as an initiating reaction step in the formation
see Exp. Sect.). Attempts to isolate supposed intermediate
of the dimer 7 is in accordance with the fact that 4 exhibits
G in pure form proved to be unsuccessful. This was ascribed
an electrophilic iodine atom and I···I– contacts in solid
to the fact that isomers of G can be formed via [1,5]-sigma-
state.[13] The tendency for such symmetric halogen···
tropic shifts of the proton bound to the cyclopentadienyl
halogen– contacts to be formed decreases with the atomic
ring and to the fact that this CH-acid is prone to be depro-
number of the halogen atoms involved.[14] In order to find
tonated by the base triphenylmethylenephosphorane pres-
stronger evidence of an X+ abstraction as the initial reac-
ent. Attempts to independently synthesise G by reaction of
tion step in the dimerisations described here, the phos-
phosphane 1 with X+ donors such as iodine, N-bromosuc-
phonium bromide 3 was characterised by means of X-ray
cinimide or hexachloroethane at low reaction temperatures
analysis (Figure 2). Indeed, this compound also exhibits
proved to be unsuccessful as they are less selective, probably
Br···Br contacts in solid state indicated by a Br1–Br2 dis-
due to direct halogenation at the cyclopentadienyl substitu-
tance of 3.568(1) Å, which is 4% below the doubled value
ent. (ii) From the molecular structure of the products it can
of the van der Waals radius of bromine.[15] The Br2–Br1–
easily be deduced that the proton which was bound to the
C1 unit exhibits a bond angle of 175.4(1)° revealing an in-
cyclopentadienyl-ring in reactant 1 has been abstracted in
teraction of nucleophilic bromide Br2 with the electrophile,
the course of the reaction. Triphenylmethylenephos-
the σ*C1–Br1 orbital (LUMO), respectively. Accordingly, the
phorane, the formation and indirect detection of which is
C1–Br1 bond is slightly lengthened.[16] A C–H···Br– contact
described in (i), can act as a Brønsted base.[11] The corre-
is found in the crystal structure of the phosphonium bro-
mide 3 as an additional secondary interaction.
+
sponding protonated form, the phosphonium salt MePPh3
I–, was isolated and characterised in the case of 7. Overall,
this acid-base reaction must be undergone twice and in
agreement with these stoichiometric considerations, two
equivalents of MePPh3+ I– were isolated. With intermediate
G acting as the Brønsted acid H would be gener-
ated as an intermediate (Scheme 4). (iii) In order to achieve
the formation of the products 5–7, a six-membered hetero-
cycle must be generated. A nucleophilic displacement of the
halogen atom in assumed intermediate H is a plausible reac-
tion step, which must be undergone twice. This is equiva-
lent with a dimerisation of H.[12] So the oxidative dimeris-
ation of 1 leading to the formation of the bisphosphonium
Figure 2. Molecular structure of Ph3PCH2Br+ Br– (3); the thermal
salts 5–7 is a complex sequence of reactions including at
ellipsoids are drawn at the 50% probability level. Hydrogen atoms
are omitted for clarity. Selected bond lengths [Å] and angles [°]:
least six elementary reactions of three different kinds. A
plausible reaction mechanism, which is in agreement with
(i)–(iii), is shown in Scheme 4. The key reaction step is the
dimerisation of the proposed intermediate H, which does
not necessarily have to proceed in a concerted fashion (as
depicted in Scheme 4 for space-saving reasons) but could
also follow a stepwise mechanism.
Br1–Br2 3.568(1), Br1–C1 1.948(2), P1–C1 1.804(2), P1–C2
1.792(4), P1–C8 1.787(2), P1–C14 1.785(2), Br2–Br1–C1 175.4(1).
The Br···Br– contact in 3 provides further evidence that
sterically hindered halomethylphosphonium cations are sus-
ceptible to a nucleophilic attack at the part of the σ*C–X
orbital which is located at the halogen and not at the carb-
on atom explaining why 3 acts as halogen+ and not carb-
enium transfer agent.
Formation of a Fourfold Anellated, Phosphacyclic Dispiro
Compound
Driven by the initial motivation of our studies to find a
synthetic approach to type C ligands (Scheme 1), the (cyclo-
pentadienyl)(iodomethyl)phosphonium iodide 8 was pre-
pared as a potential target for P-nucleophiles. This synthe-
sis was achieved by reaction of cyclopentadienylphosphane
1 with diiodomethane (see upper part of Scheme 5). The
desired product was obtained as a mixture of the isomers
8a and 8b in a 58:42 ratio. When the phosphonium iodide
8 is solvated in DMSO this ratio increases up to 67:33 in
favour of the isomer 8a over a period of one day, after
Scheme 4. Proposed mechanism for the oxidative dimerisation of 1
yielding the bisphosphonium salts 5–7 (shown for 7). The dimeri-
sation of supposed intermediate H, formed by deprotonation of
intermediate G, is the key step in this mechanism.[12]
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C. Lichtenberg, M. Elfferding, J. Sundermeyer
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Scheme 5. Nucleophilic substitution reaction (upper part) and oxidative dimerisation (lower part) of cyclopentadienylphosphane 1.
which this ratio was found to be constant. The structures covering a spectrum of about 25°. The highest values of
of these substances were established by means of 2D NMR these bond angles around the sp3 carbon atoms C1 and C12
measurements (COSY, HMQC, HMBC) in addi- even exceed 120° which are ideally expected for bond angles
tion to the usual 1D NMR experiments.
with sp2 carbon atoms in the central position. Structural
Under only slightly different reaction conditions (n-hex- elements which are further apart from the two spiro centres
ane/THF, 50–90 °C, 9 d) 9 was obtained as a completely are still affected by the ring strain, but to a lesser extend.
unexpected side product of this reaction (lower part, The endocyclic bonds in the dication of 9 (apart from C1–
Scheme 5).
C12, which was discussed above) are with few exceptions
In this case, diiodomethane does not act as an electro- slightly stretched. In the crystal structure of the bisphos-
phile but as an iodine radical donor. Whereas variations of phonium iodide 9 there is also a secondary binding interac-
the ratio of tetrahydrofuran in the solvent mixture did not
have a significant impact on the outcome of the experiment,
an elevation of the reaction temperature and reaction time
led to an increase in the selectivity towards 9. Under op-
timised reaction conditions the formation of the heterocy-
clic compound 9 was achieved with a selectivity of 30%. 8a
and 8b were also observed as well as a fourth substance
with a composition [CH2(PMe2Cp#)2]I2 (Cp# = C5HMe4)
tentatively assigned on the basis of high resolution ESI
mass spectra. After several crystallisations, small amounts
of the phosphonium iodide 9 could be obtained in an ana-
lytically pure form. Six pairs of methyl groups, five pairs of
endocyclic carbon atoms and the two phosphorus atoms of
this substance are isochronical. This indicates that the dicat-
ion of the bisphosphonium salt 9 shows C2-symmetry in Figure 3. Molecular structure of the bisphosphonium iodide 9;
thermal ellipsoids are shown at the 50% probability level. Hydro-
gen atoms except for H1 are omitted for clarity. Two molecules of
solution. The molecular structure of 9 was indubitably es-
tablished by X-ray analysis (Figure 3). In solid state 9 exhi-
methanol are incorporated into the crystal structure of 9. One of
bits non-crystallographic C1 symmetry. Like the phos-
these is disordered, does not interact with 9 and is therefore not
phonium salts 5–7, it originates from an oxidative dimeri-
sation of the cyclopentadienylphosphane 1. The unexpected
product 9 is a fourfold anellated, partially unsaturated,
heterocyclic compound. Two spiro centres, which are di-
rectly linked, are incorporated into this cyclic framework.
shown. Selected bond lengths [Å] and angles [°]: C1–C12 1.626(4),
P1–C3 1.835(3), P1–C10 1.783(3), P1–C11 1.783(3), P1–C12
1.832(2), P2–C1 1.842(2), P2–C15 1.837(3), P2–C21 1.784(2), P2–
C22 1.785(2), C1–C2 1.562(2), C2–C3 1.557(3), C3–C4 1.528(3),
C4–C5 1.338(2), C5–C1 1.539(3), C12–C13 1.537(2), C13–C14
1.337(3), C14–C15 1.525(3), C15–C16 1.552(3), C16–C12 1.549(3),
The combination of these features makes this bisphosphon- H1–I1 2.623(41), P1–C12–C1 100.2(1), P1–C12–C13 124.6(1), P1–
C12–C16 116.5(1), C1–C12–C13 106.9(2), C1–C12–C16 106.0(2),
P2–C1–C2 117.7(1), P2–C1–C5 124.4(1), P2–C1–C12 99.5(1), C2–
C1–C12 105.3(3), C5–C1–C12 107.6(2), C3–P1–C10 109.1(1), C3–
P1–C11 113.9(1), C3–P1–C12 95.7(1), C10–P1–C11 107.5(1), C10–
ium iodide unique in its structural characteristics. They also
lead to a high degree of ring strain within the dication,
which is the dominating property of this molecule. This
leads to strong deviations of most of the bond lengths and
angles from values which would be expected for unstrained
systems. The most remarkable examples of this are found
around the two spiro centres, C1 and C12. The C–C bond
linking these atoms is stretched to 1.626(4) Å. The bond
P1–C12 113.5(1), C11–P1–C12 116.8(1), C1–P2–C15 95.6(1), C1–
P2–C21 118.6(1), C1–P2–C22 112.6(1), C15–P2–C21 111.0(1),
C15–P2–C22 112.4(1), C21–P2–C22 106.5(1), C1–C2–C3 95.8(2),
C2–C3–C4 100.6(2), C3–C4–C5 109.8(2), C4–C5–C1 107.3(2), C5–
C1–C2 100.7(2), C12–C13–C14 107.2(2), C13–C14–C15 109.5(2),
C14–C15–C16 101.3(2), C15–C16–C12 95.9(2), C16–C12–C13
angles at both spiro centers range from 99.5(1) to 124.4(1)° 101.2(2), O1–H1–I1 179.1(35).
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Oxidative Dimerisations of a Cyclopentadienyl-Phosphane
tion. This is an H···I– contact, in which the hydrogen atom Mechanistic aspects of these reactions have been investi-
belongs to the hydroxy group of a solvent molecule gated and an X+ abstraction from the electrophile and ox-
(MeOH). The hydrogen bond H1–I1 exhibits a length of idising agent by cyclopentadienylphosphane 1 has been es-
2.623(41) Å, which is more than 17% below the sum of the tablished as the initiating reaction step. In the fourth exam-
van der Waals radii[15] and an O1–H1–I1 bond angle of ple of an oxidative dimerisation of cyclopentadienylphos-
179.1(35)°.
phane 1 diiodomethane is acting as oxidising agent, pre-
Mechanistic considerations concerning the formation of sumably via iodine radical instead of a carbon electrophile
the bisphosphonium iodide 9 shall be discussed in brief. transfer leading to expected 8a,b. The unexpected product
The chemical formula of the product, (PMe2Cp#I)2, indi- 9 of this reaction has been characterised by X-ray analysis
cates that overall an iodine radical addition to the cyclopen- and exhibits highly remarkable structural features. It is a
tadienyl-phosphane 1 followed by a dimerisation of the re- fourfold anellated, partially unsaturated, heterocyclic com-
sulting radical intermediate has taken place. Such an iodine pound with two spiro carbon centres, which are directly
radical transfer to the cyclopentadienylphosphane 1 would linked to each other.
result in the formation of intermediate I with resonance for-
mulae Ia, Ib and Ic shown in Scheme 6. Product 9 is a dimer
of I.
Experimental Section
General: All experimental procedures were carried out in an atmo-
sphere of purified argon or nitrogen using standard Schlenk tech-
niques or a glovebox. The solvents used were dried and degassed
according to standard protocols. Chemicals were purchased from
Alfa Aesar, Aldrich or Merck and used without further purifica-
tion. PClMe2,[17] LiCp#[18] (Cp# = C5HMe4), PPh3CH2X+ X– (X =
[22]
Cl,[19] Br,[20] I[21]) and PPh3CH2
were synthesised according to
Scheme 6. Resonance structures of supposed intermediate Ia, Ib
and Ic (formed probably as P–I contact ion pairs) as result of an
iodine radical interaction with the cyclopentadienylphosphane 1.
literature procedures. NMR measurements were performed using a
Bruker AVANCE 300, DRX 400 or DRX 500 spectrometer at
25 °C. Elemental analyses were carried out at the Analytical Labo-
ratory of the Department of Chemistry, Philipps University of
Marburg. ESI mass spectra were recorded using a Finnigan TSQ
It is important to note that Ia represents an electrophilic
radical, whereas Ib and Ic are nucleophilic radicals. Dimer-
isation of radical Ia with sterically less hindered Ic would 700 instrument.
generate K as an intermediate (Scheme 7). Two intramolec-
ular P–C bond formations in transient K, probably via a
polar mechanism, would lead to isolated product 9.
PMe2Cp# (1): Method A:
A solution of Me2PCl (364 mg,
3.77 mmol) in toluene (2.25 mL) was added to a suspension of
LiCp# (507 mg, 3.96 mmol) in n-pentane/diethyl ether (1:1)
(24 mL) at 0 °C. The reaction mixture was warmed up to room
temperature over 17 h, after which the volume of the liquid phase
was reduced to half in vacuo at 0 °C. The solid was separated by
filtration and washed with n-pentane (3ϫ8 mL). The colourless
filtrate was used as a source of the phosphane 1 in one of the
following reactions. Method B: See method A, but neat n-pentane
was used as a solvent. Moreover, the volume of the liquid phase
was not reduced to half in vacuo prior to filtration. Method C: See
method A, but n-hexane/tetrahydrofuran (2:1) was used as a solvent
mixture. –78 °C was chosen as the initial reaction temperature in-
stead of 0 °C.
Scheme 7. Proposed stepwise mechanism for the formation of 9 via
intermediate K, which would be formed by dimerisation of the radi-
cal intermediate I.
Isolation of PMe2Cp# (1):[23] 1 was prepared according to method
A. Removal of all volatiles under reduced pressure at 0 °C yielded
a colourless oil which was then dried in vacuo; yield 557 mg (81%).
1 was isolated as a mixture of three isomers.
Conclusions
Dimethyl(2,3,4,5-tetramethylcyclopenta-2,4-dienyl)phosphane (1a,
Four cases of unexpected oxidative dimerisations of the
cyclopentadienylphosphane Me2PCp# (1) (Cp# = C5HMe4)
have been reported. In sharp contrast to known reactions
of Ph3PCH2X+ X– (X = Cl, Br, I) with PPh3, the former
phosphonium salts act as halogen+ (not carbenium ion)
transfer agents towards phosphane 1. In a second reaction
step the resulting leaving group triphenylmethylenephos-
phorane acts as a Brønsted base leading to a formal H+ by
I+ exchange. A group-15 analogue of octamethyl-tetra-
hydro-s-indacene with X– counterions is the final reaction
product in each of these reactions. The first example of an
1
2
75%): H NMR (300.1 MHz, C6D6): δ = 0.84 (d, JHP = 5.0 Hz, 6
H, PMe2), 1.73 (s, 6 H, 3,4-CpMe2), 1.93 (s, 6 H, 2,5-CpMe2), 2.80
(br. s, 1 H, 1-CpH) ppm. 13C NMR (75.5 MHz, C6D6): δ = 9.5 (d,
1JCP = 19.4 Hz, PMe2), 11.2 (s, 3,4-CpMe2), 14.3 (d, 3JCP = 8.3 Hz,
1
2
2,5-CpMe2), 57.9 (d, JCP = 22.7 Hz, 1-Cp), 134.1 (d, JCP
=
2.3 Hz, 2,5-Cp), 136.2 (d, JCP = 2.7 Hz, 3,4-Cp) ppm. 31P NMR
3
(121.5 MHz, C6D6): δ = –37.1 ppm.
Dimethyl(2,3,4,5-tetramethylcyclopenta-1,3-dienyl)phosphane (1b,
1
3
15%): H NMR (300.1 MHz, C6D6): δ = 1.08 (d, JHH = 7.6 Hz,
3 H, 5-CpMe), 1.18 (d, JHP = 3.6 Hz, 3 H, PMe1/2), 1.19 (d, JHP
2
2
= 3.5 Hz, 3 H, PMe2/1), 1.65 (s, 3 H, 3-CpMe), 1.73 (3 H, 4-CpMe,
X-ray analysis of such a heterocyclic compound is reported. overlapped by the resonance due to 3,4-CpMe2 of 1a), 2.09 (s, 3 H,
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C. Lichtenberg, M. Elfferding, J. Sundermeyer
FULL PAPER
2-CpMe) 2.80 (1 H, 5-CpH, overlapped by the resonance due to 1-
PMePh3I:[24] Two equivalents of this phosphonium salt were ob-
CpH of 1a) ppm. 13C NMR (75 MHz, C6D6): δ = 11.0 (s, 3-CpMe), tained from the filtrate of the reaction mixture in the case of X =
1
1
11.0 (s, 4-CpMe), 13.4 (d, JCP = 26.7 Hz, PMe1/2), 13.5 (d, JCP
=
=
I by removal of the solvent in vacuo. The white solid was washed
with diethyl ether (2ϫ5 mL) and n-pentane (2ϫ7 mL) and dried
in vacuo. ESI-MS: exact mass calcd. for C19H18P+: m/z = 277.1141,
found m/z (%) = 277.1144 (100) [(M – I–)+]. I–: m/z = 126.9050,
found m/z (%) = 126.9052 (98) [I–]. 1H NMR (300.1 MHz, [D6]-
27.7 Hz, PMe2/1), 13.9 (d, 3JCP = 5.9 Hz, 2-CpMe), 15.8 (d, 3JCP
2
1.5 Hz, 5-CpMe), 52.2 (d, JCP = 4.3 Hz, 5-Cp) ppm. Resonances
arising from four C atoms being part of the five-membered ring
could not be detected due to the low ratio of this isomer. 31P NMR
(121.5 MHz, C6D6): δ = –67.3 ppm.
2
DMSO): δ = 3.16 (d, JHP = 14.6 Hz, 3 H, Me), 7.74–7.89 (m, 15
H, Ph) ppm. 31P NMR (121.5 MHz, [D6]DMSO): δ = 21.5 ppm.
Dimethyl(1,2,3,4-tetramethylcyclopenta-2,4-dienyl)phosphane (1c,
1
2
Indirect Proof for PPh3CH2 Intermediate: A solution of PMe2Cp#
(1) was prepared following the procedure described in method A,
but the reaction was downscaled to 1:10. The solvent was removed
in vacuo at 0 °C to give a colourless oil, which was dissolved in
acetonitrile (1.5 mL) and cooled to 0 °C. The chilled solution was
added to a suspension of Ph3PCH2I+ I– (0.16 g, 0.30 mmol) in ace-
tonitrile (2 mL) at 0 °C. After 3 min sonofication at 0 °C, the sus-
pension was transferred to an NMR tube, solid material was centri-
fuged into the top of the NMR tube and the yellow solution was
analysed by means of 31P NMR spectroscopy (121.5 MHz, δ =
21.8 ppm, purity at least 80%). Addition of authentic neat
PPh3CH2 to the soluble part of the reaction mixture did not change
the spectrum except for an increase in the intensity of the main
resonance.
10%): H NMR (300.1 MHz, C6D6): δ = 0.50 (d, JHP = 4.5 Hz, 3
H, PMe1/2), 0.84 (d, JHP = 4.9 Hz, 3 H, PMe2/1), 1.23 (d, JHP
=
2
3
14.6 Hz, 3 H, 1-CpMe), 1.68 (s, 3 H, 3-CpMe), 1.82 (s, 3 H, 2-
CpMe), 1.86 (s, 3 H, 4-CpMe), 5.77 (br. s, 1 H, 5-CpH) ppm. 13C
1
NMR (75.5 MHz, C6D6): δ = 8.5 (d, JCP = 18.1 Hz, PMe1/2), 10.9
(s, 2-CpMe, partially overlapped by the resonances due to 3-CpMe
and 4-CpMe of 1b), 11.3 (d, 1JCP = 19.8 Hz, PMe2/1, partially over-
lapped by 3,4-CpMe2 von 1a), 13.8 (s, 4-CpMe, partially over-
2
lapped by the resonance due 2-CpMe of 1b), 17.2 (d, JCP
=
=
1
2
19.9 Hz, 1-CpMe) 53.9 (d, JCP = 17.8 Hz, 1-Cp) 132.0 (d, JCP
3.1 Hz, 5-Cp) ppm. Resonances due to four C atoms of 1c could
not be detected due to the low ratio of this isomer. 31P NMR
(121.5 MHz, C6D6): δ = –25.9 ppm.
[PMe2(C5Me4)]2X2 (5, X = Cl; 6, X = Br; 7, X = I): A solution of
PMe2Cp# (1), was prepared according to method A. The solvent
was removed in vacuo at 0 °C to give a colourless oil, which was
dissolved in acetonitrile (15 mL) and slowly added to a suspension
of Ph3PCH2X+ X– (X = Cl: 1.05 g, 3.02 mmol; X = Br: 1.32 g,
3.03 mmol; X = I: 1.60 g, 3.02 mmol) in acetonitrile (20 mL). The
reaction mixture was allowed to stir for an appropriate time span
(X = Cl: 12 h, X = Br, I: 2 h). After that the white solid was filtered
off, washed with acetonitrile (3ϫ4 mL) and diethyl ether
(3ϫ4 mL) and dried in vacuo.
PMe2Cp#(CH2I)I (8a, 8b): A solution of PMe2Cp# (1) was pre-
pared according to method B and its volume was reduced to 15 mL
in vacuo at 0 °C. Toluene (15 mL) and diiodomethane (1.28 g,
4.78 mmol) were added and the reaction mixture was heated to
45 °C for 65 h. The product precipitated as a white, microcrystalline
solid. It was separated by filtration, washed with n-pentane
(3ϫ8 mL) and dried in vacuo. Heating the filtrate to 45 °C for
additional 9 d gave another crop of the product, which was isolated
as described above. The product was obtained as a mixture of the
two isomers 8a and 8b (58:42). Combined yield 1.12 g (66%), ESI-
MS: exact mass calcd. for C12H21IP+: m/z = 323.0420, found
m/z (%) = 323.0416 (100) [(M – I–)+]. C12H21I2P (450.08): calcd.
C 32.02, H 4.70, found C 32.11, H 5.08. 8a: 1H NMR (300.1 MHz,
5·2 MeCN (X = Cl): Yield 413 mg (53%), ESI-MS: exact mass
calcd. for C22H35P2+: m/z = 361.2209, found m/z (%) = 361.2215(9)
[(M – 2 Cl– – H+)+]. C22H36P22+: m/z = 181.1141, found m/z (%) =
181.1140 (100) [(M – 2 Cl–)2+]. C26H42Cl2N2P2 (515.48): calcd.
1
4
C 60.58, H 8.21, N 5.43, found C 60.66, H 8.42, N 5.18. H NMR
[D6]DMSO): δ = 1.18 (bd, JHP = 7.5 Hz, 3 H, 5-CpMe), 1.82 (s,
2
2
(300.1 MHz, [D6]DMSO): δ = 1.52 (d, JHP = 17.6 Hz, 3 H, PMe),
3 H, 3-CpMe), 1.93 (s, 3 H, 4-CpMe), 2.17 (d, JHP = 13.7 Hz, 3
2
4/5
2
1.74 (d, JHP = 13.6 Hz, 3 H, PMe), 1.95 [d,
J
HP
= 1.7 Hz, 3 H,
H, PMe), 2.18 (d, JHP = 13.8 Hz, 3 H, PMe), 2.19 (s, 3 H, 2-
C(sp2)Me], 2.13 [s, 3 H, C(sp2)Me], 2.39 [s, 3 H, C(sp2)Me], 2.58
2
2
CpMe), 3.30 (d, JHP = 6.3 Hz, 1 H, 5-CpH), 3.83 (d, JHP
=
[d, JHP = 13.9 Hz, 3 H, C(sp3)Me] ppm. 31P NMR (121.5 MHz,
3
8.2 Hz, 2 H, CH2I) ppm. 31P NMR (121.5 MHz, [D6]DMSO): δ =
17.3 ppm. 13C NMR (75.5 MHz, [D6]DMSO): δ = –11.1 (d, JCP
1
[D6]DMSO): δ = 26.7 ppm.
1
1
= 52.8 Hz, CH2I), 9.7 (d, JCP = 57.7 Hz, PMe), 9.8 (d, JCP
=
6·2 MeCN (X = Br): Yield 494 mg (54%), ESI-MS: exact mass
calcd. for C22H35P2+: m/z = 361.2209, found m/z (%) = 361.2218
(5) [(M – 2 Br– – H+)+]. C22H36P22+: m/z = 181.1141, found m/z (%)
= 181.1140 (100) [(M – 2 Br–)2+]. C26H42Br2N2P2 (604.38): calcd.
57.9 Hz, PMe), 10.3 (s, 3-CpMe), 12.4 (d, 4JCP = 1.1 Hz, 4-CpMe),
14.8 (d, 3JCP = 3.6 Hz, 5-CpMe), 14.9 (s, 2-CpMe), 52.1 (d, 2JCP
=
=
=
1
3
13.1 Hz, 5-Cp), 115.7 (d, JCP = 95.4 Hz, 1-Cp), 135.5 (d, JCP
15.9 Hz, 3-Cp), 154.0 (d, JCP = 8.3 Hz, 4-Cp), 164.1 (d, JCP
10.8 Hz, 2-Cp) ppm. 8b: H NMR (300.1 MHz, [D6]DMSO): δ =
1.81 (d, JHP = 4.2 Hz, 6 H, 2,5-CpMe2), 1.91 (d, JHP = 13.7 Hz,
3
2
1
C 51.67, H 7.00, N 4.64, found C 51.87, H 6.65, N 5.03. H NMR
1
2
(300.1 MHz, [D6]DMSO): δ = 1.51 (d, JHP = 17.6 Hz, 3 H, PMe),
4
2
2
1.72 (d, JHP = 13.6 Hz, 3 H, PMe), 1.95 [s, 3 H, C(sp2)Me], 2.13
2
[s, 3 H, C(sp2)Me], 2.38 [s, 3 H, C(sp2)Me], 2.55 [d, 3JHP = 13.8 Hz,
3 H, C(sp3)Me] ppm. 31P NMR (121.5 MHz, [D6]DMSO): δ =
26.7 ppm.
6 H, PMe2), 1.99 (s, 6 H, 3,4-CpMe2), 3.57 (d, JHP = 8.4 Hz, 2
H, CH2I) 4.34 (d, JHP = 23.7 Hz, 1 H, 1-CpH) ppm. 31P NMR
2
(121.5 MHz, [D6]DMSO): δ = 31.2 ppm. 13C NMR (75.5 MHz,
1
1
[D6]DMSO): δ = –14.9 (d, JCP = 47.4 Hz, CH2I), 6.7 (d, JCP
=
7 (X = I): Yield 651 mg (70%), ESI-MS: exact mass calcd. for
3
53.7 Hz, PMe2), 11.4 (d, JCP = 1.5 Hz, 2,5-CpMe2), 13.8 (s, 3,4-
C22H35P2+: m/z = 361.2209, found m/z (%) = 361.2216 (5) [(M –
1
3
CpMe2), 50.8 (d, JCP = 39.2 Hz, 1-Cp), 127.9 (d, JCP = 5.2 Hz,
2+
2 I– – H+)+]. C22H36P2
: m/z = 181.1141, found m/z (%) =
2
3,4-Cp), 143.5 (d, JCP = 7.9 Hz, 2,5-Cp) ppm.
181.1140 (100) [(M – 2 I–)2+]. C24H36I2P2 (616.28): calcd. C 42.88,
H 5.89, found C 42.85, H 5.89. 1H NMR (300.1 MHz, [D6]-
(PCp#Me2)2I2 (9): A solution of PMe2Cp# (1) was prepared ac-
cording to method C and its volume was reduced to 12 mL in
2
2
DMSO): δ = 1.51 (d, JHP = 17.4 Hz, 3 H, PMe), 1.71 (d, JHP
=
4/5
13.6 Hz, 3 H, PMe), 1.95 [d,
J
HP
= 2.1 Hz, 3 H, C(sp2)Me], 2.12 vacuo at 0 °C. In a pressure tube with teflon valve n-hexane
[s, 3 H, C(sp2)Me], 2.37 [s, 3 H, C(sp2)Me], 2.54 [d, 3JHP = 14.0 Hz, (12 mL) and diiodomethane (496 mg, 1.85 mmol) were added and
3 H, C(sp3)Me] ppm. 31P NMR (121.5 MHz, [D6]DMSO): δ =
the reaction mixture was kept at 50 °C for 60 h, then at 70 °C for
100 h and finally at 90 °C for 66 h. A white solid had precipitated
26.6 ppm.
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Eur. J. Inorg. Chem. 2010, 3117–3124

Oxidative Dimerisations of a Cyclopentadienyl-Phosphane
and was separated by filtration, washed with n-pentane (3ϫ10 mL)
and dried in vacuo. Next to main product 8a,b this salt mixture
contained about 30% spectroscopic yield of 9 (1H-, 31P NMR) as
parameters. Storage of an oversaturated solution of 3 in Pe/EtOAc/
MeOH (2:1:1) for 7 d yielded colourless single crystals of this sub-
stance.
well as about 30% of
a
second by-product, presumably
Crystal Data for 7: C13H24IOPS, Mr = 386.25, triclinic, P1, a =
6.995(5) Å, b = 9.679(5) Å, c = 12.789(5) Å, α = 80.452(5)°, β =
75.801(5)°, γ = 73.601(5)°, V = 800.9(8) Å3, Z = 2, ρ(calcd.) =
1.602 gcm–3, µ = 2.215 mm–1, T = 100 K. A total of 8111 reflec-
tions were collected, of which 2825 were independent. Hydrogen
atoms were included at calculated positions with fixed thermal pa-
rameters. The refinement on all data converged at R1 = 2.12%, wR2
= 4.48% and the goodness of fit was 0.940. In the asymmetric unit
one DMSO molecule is included. Colourless single crystals of 7
were grown from a saturated solution of this bisphosphonium salt
in DMSO by gas phase diffusion (Et2O) at room temperature.
(CH2(PMe2(C5Me4))I2 (1H-, 31P NMR, ESI-MS). The salts were
then suspended in dichloromethane (20 mL). Separation of the so-
lid and the liquid phase was achieved by centrifugation followed
by decantation. Storage of a saturated solution of the DCM insolu-
ble solid part in methanol at 4 °C gave colourless crystals of the
pure product 9; yield 23 mg (2%), ESI-MS: exact mass calcd. for
C22H38IP2+: m/z = 491.1488, found m/z (%) = 491.1488 (100) [(M –
I–)+].
Crystal Data for 9: C23.50H43I2O2P2, Mr = 673.34, triclinic, P1, a
= 10.9375(4) Å, b = 10.9411(4) Å, c = 14.1493(5) Å, α = 90.172(3)°,
β = 107.398(3)°, γ = 119.288(3)°, V = 1386.36(9) Å3, Z = 2,
ρ(calcd.) = 1.613 gcm–3, µ = 2.401 mm–1, T = 100 K. A total of
18094 reflections were collected, of which 4871 were independent.
The refinement on all data converged at R1 = 1.79%, wR2 = 4.27%
and the goodness of fit was 1.017. In the asymmetric unit two
MeOH molecules are included, of which one is disordered and was
modelled as two sites with 60:40 occupancy. The appropriate car-
bon atom of the disordered MeOH molecule resides on a crystallo-
graphic inversion center with a site-occupation factor of 0.5. The
corresponding OH hydrogen atom could not be located in the dif-
ference Fourier map and was therefore fixed using the riding model,
while the OH hydrogen atom at the second MeOH molecule was
fixed in his located position. All other hydrogen atoms were in-
cluded at calculated positions with fixed thermal parameters. Single
crystals of 9 were obtained by cooling a saturated solution in
MeOH to 4 °C.
3
1H NMR (300.1 MHz, [D6]DMSO): δ = 0.94 (d, JHH = 5.7 Hz, 6
H, Me3,9), 1.42 (d, JHP = 18.0 Hz, 6 H, Me6,12), 1.70 (d, JHP
=
3
4
5.9 Hz, 6 H, Me4,10), 1.78 (s, 6 H, Me5,11), 2.19 (d, 2JHP = 12.7 Hz,
6 H, Me1,7/2,8), 2.22 (d, JHP = 13.6 Hz, 6 H, Me2,8/1,7), 3.08–3.11
2
(m, 2 H, CMe3H, CMe9H) ppm. 31P NMR (121.5 MHz, [D6]-
DMSO): δ = 40.1 ppm. 13C NMR (125.8 MHz, [D6]DMSO): δ =
5.3 (d, JCP = 46.0 Hz, Me1,7/2,8), 5.7 (d, JCP = 42.2 Hz, Me2/1),
1
1
8.3 (dd, JCP = 4.1, JCP = 3.5 Hz, Me3,9), 9.0 (s, Me6,12), 11.5 (s,
3
4
Me5,11), 15.7 (s, Me4,10), 54.5 (dd, JCP = 6.1, JCP = 6.3 Hz,
2
3
CHMe3,9), 56.1 (dd, 1JCP = 47.5, 3JCP = 9.9 Hz, CMe6,12), 134.5 (s,
CMe5,11), 137.2 (dd, JCP = 6.0, JCP = 6.4 Hz, CMe4,10) ppm.
2
3
[CH2(PMe2Cp#)2]I2: The data were obtained from the product mix-
ture prior to recrystallisation from methanol. ESI-MS: exact mass
calcd. for C23H39P2+: m/z = 377.2522, found m/z (%) = 377.2522
(4) [(M – H+ – 2 I–)+]. 31P NMR (121.5 MHz, [D6]DMSO): δ =
16.0 ppm.
[1] a) H. Braunschweig, F. M. Breitling, Coord. Chem. Rev. 2006,
250, 2691–2720; b) J. Okuda, Dalton Trans. 2003, 2367–2378;
c) J. Cano, K. Kunz, J. Organomet. Chem. 2007, 692, 4411–
4423.
X-ray Crystallographic Studies: Crystallography: Crystal data were
collected with a Stoe-IPDSII area-detector diffractometer using
graphite-monochromatised Mo-Kα-radiation (λ = 71.073 pm) at
100 K. The detector was placed at a distance of 1.2 cm from the
crystal. Data reduction was carried out by using the IPDS software
X-Area (Stoe).[25] The data were empirically corrected for absorp-
tion and other effects by using multiscans.[26] The structures were
solved by direct methods (Sir-97)[27] and refined by full-matrix le-
ast-squares techniques against Fo2 (SHELXL-97).[28] The programs
PLATON[29] and PLUTON[30] were used to check the results of the
X-ray analyses. Diamond was used for structure representations.[31]
[2] a) J. A. M. Canich (Exxon), U. S. Patent, 5 096 867, 1992; b)
B. A. Harrington, G. G. Hlatkey, J. A. M. Canich, N. A. Mer-
rill (Exxon), U. S. Patent 5 635 573, 1997.
[3] a) P. J. Shapiro, E. Bunel, W. P. Schaefer, J. E. Bercaw, Organo-
metallics 1990, 9, 867–869; b) J. Okuda, Chem. Ber. 1990, 123,
1649–1651.
[4] A. R. Petrov, K. A. Rufanov, B. Ziemer, P. Neubauer, V. V. Ko-
tov, J. Sundermeyer, Dalton Trans. 2008, 909–915.
[5] K. A. Rufanov, A. R. Petrov, V. V. Kotov, F. Laquai, J. Sun-
dermeyer, Eur. J. Inorg. Chem. 2005, 3805–3807.
[6] F. Ramirez, N. B. Desai, H. Hansen, N. McKelvie, J. Am.
Chem. Soc. 1961, 83, 3539–3540.
[7] C. Zybill, G. Müller, Organometallics 1987, 6, 2489–2494.
[8] a) P. Jutzi, T. Heidemann, B. Neumann, H. G. Stammler, Syn-
thesis 1992, 1096–1098; b) S. Ford, M. Hofmann, C. P. Morley,
J. L. Roberts, M. di Vaira, Org. Biomol. Chem. 2005, 3, 3990–
3995.
[9] A phosphane oxide derivative has been described, see: S.
Schardt, K. Hafner, Tetrahedron Lett. 1996, 37, 3829–3832.
[10] a) R. G. Pearson, J. Am. Chem. Soc. 1963, 85, 3533–3539; b)
R. G. Pearson, Science 1966, 151, 172–177; c) R. G. Pearson in
Hard and Soft Acids and Bases (Ed.: R. G. Pearson), Dowden,
Hutchinson and Ross, Stroudsburg, PA, 1973, vol. 1, pp. 79–
84; d) R. S. Drago, G. C. Vogel, T. E. Needham, in: Hard and
Soft Acids and Bases (Ed.: R. G. Pearson), Dowden, Hutchin-
son and Ross, Stroudsburg, PA, 1973, vol. 1, pp. 267–279.
[11] Y. Fu, H.-J. Wang, S.-S. Chong, Q.-X. Guo, L. Liu, J. Org.
Chem. 2009, 74, 810–819.
CDC-753501 (for 3), -753500 (for 7) and -753502 (for 9) contain
the supplementary crystallographic data for this paper. These data
can be obtained free of charge from The Cambridge Crystallo-
graphic Data Centre via www.ccdc.cam.ac.uk/data_request/cif.
Crystal Data for 3: C19H17Br2P, Mr = 436.12, monoclinic, P21/n, a
= 10.2226(4) Å, b = 14.0098(5) Å, c = 12.4510(5) Å, α = 90°, β =
104.960(3)°, γ = 90°, V = 800.9(8) Å3, Z = 4, ρ(calcd.) =
1.681 gcm–3, µ = 4.792 mm–1, T = 100 K. A total of 9908 reflec-
tions were collected, of which 3034 were independent. The refine-
ment on all data converged at R1 = 2.00%, wR2 = 4.44% and the
goodness of fit was 0.939. Hydrogen atoms were included in ideal-
ised positions and refined with isotropic displacement parameters
except that corresponding with the CH2P group, which was found
in the final density map and refined with isotropic displacement
Eur. J. Inorg. Chem. 2010, 3117–3124
© 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
3123

C. Lichtenberg, M. Elfferding, J. Sundermeyer
FULL PAPER
[12] The dimerisation of a halophosphorane has been described
previously, see: a) R. Appel, F. Knoll, H.-D. Wihler, Angew.
Chem. 1977, 89, 415–416; R. Appel, F. Knoll, H.-D. Wihler,
Angew. Chem. Int. Ed. Engl. 1977, 16, 402–403; b) J. Weiss, B.
Nuber, Z. Anorg. Allg. Chem. 1981, 473, 101–106.
[13] H. Vogt, K. Lauritsen, L. Riesel, M. von Löwis, G. Reck, Z.
Naturforsch., Teil B 1993, 48, 1760–1766.
[14] a) F. Ruthe, W.-W. du Mont, P. G. Jones, Chem. Commun. 1997,
1947–1948; b) N. Bricklebank, S. M. Godfrey, A. G. Mackie,
C. A. MacAuliffe, R. G. Pritchard, J. Chem. Soc., Chem. Com-
mun. 1992, 355–356; c) S. M. Godfrey, D. G. Kelly, C. A.
McAuliffe, A. G. Mackie, R. G. Pritchard, S. M. Watson, J.
Chem. Soc., Chem. Commun. 1991, 1163–1164; d) M. Freytag,
P. G. Jones, B. Ahrens, A. K. Fischer, New J. Chem. 1999, 23,
1137–1139.
[15] A. Bondi, J. Phys. Chem. 1964, 68, 441–451.
[16] For comparison with C–Br bonds in phosphonium salts see,
for example: M. ul-Haque, W. Horno, S. E. Cremer, P. W.
Kremer, P. K. Kafarski, J. Chem. Soc. Perkin Trans. 2 1981,
1138–1142.
[17] G. W. Parshall, Inorganic Syntheses, 15, Wiley VCH, New
York, 1974, S. 191–193.
[21]
[22]
[23]
J. C. Conway, P. Quayle, A. C. Regan, C. J. Urch, Tetrahedron
2005, 61, 11910–11923.
H. Schmidbaur, H. Stühler, W. Vornberger, Chem. Ber. 1972,
105, 1084–1086.
A synthetic approach to compound 1, which is very similar to
ours, has been reported before: M. Visseaux, A. Dormond,
M. M. Kubicki, C. Moïse, D. Baudry, M. Ephritikhine, J. Or-
ganomet. Chem. 1992, 433, 95–106.
For NMR spectroscopic identification of this substance, see:
A. Singh, Phosphorus Sulfur Silicon 1990, 49, 152–162.
Stoe & Cie GMBH, IPDS Software, Darmstadt, Germany,
1996.
R. H. Blessing, Acta Crystallogr., Sect. A 1995, 51, 33–38.
[24]
[25]
[26]
[27] A. Altomare, M. C. Burla, M. Camalli, G. L. Cascarano, C.
Giacovazzo, A. Guagliardi, A. G. G. Moliterni, G. Polidori, R.
Spagna, J. Appl. Crystallogr. 1999, 32, 115–119.
[28] G. M. Sheldrick, SHELXL-97, University of Göttingen, Ger-
many, 1993.
[29] A. L. Spek, Acta Crystallogr., Sect. A 1990, 46, C34.
[30] A. L. Spek, Platon: A Multi-Purpose Crystallographic Tool,
Utrecht University, Utrecht, The Netherlands, 2001.
[31] K. Brandenburg, Diamond, release 3.0, Crystal Impact GbR,
Bonn, Germany, 2004.
[18] C. M. Fendrick, L. D. Schertz, V. W. Day, T. J. Marks, Organo-
metallics 1988, 7, 1828–1838.
[19] R. Appel, W. Morbach, Synthesis 1977, 699–700.
[20] N. J. Lawrence, J. Liddle, D. Jackson, J. Chem. Soc. Perkin
Trans. 1 2002, 2260–2267.
Received: December 31, 2009
Published Online: June 2, 2010
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Eur. J. Inorg. Chem. 2010, 3117–3124