Alkyl and aryl dicationic derivatives of cyclic triphosphenium ions

Article abstract of DOI:10.1039/b716027e

Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for small organic substituents on the attacking reagent. The dicationic products are not intrinsically unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by Schmidpeter and co-workers. These species may be readily identified in solution by ³¹P NMR spectroscopy. The crystal and molecular structures of five such derivatives have been ascertained for the first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P-P bond lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium ions, where structural determinations have shown that the P-P bond lengths are intermediate between single and double bonds. The Royal Society of Chemistry.

Full text of DOI:10.1039/b716027e

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www.rsc.org/dalton | Dalton Transactions
Alkyl and aryl dicationic derivatives of cyclic triphosphenium ions†‡
Keith B. Dillon,* Andre´s E. Goeta, Judith A. K. Howard, Philippa K. Monks,
Helena J. Shepherd and Amber L. Thompson§
Received 18th October 2007, Accepted 17th December 2007
First published as an Advance Article on the web 16th January 2008
DOI: 10.1039/b716027e
Direct alkylation of cyclic triphosphenium ions by triflates to give di-ium dications is only possible for
small organic substituents on the attacking reagent. The dicationic products are not intrinsically
unstable, however, and in many instances they may be synthesised by an alternative route, pioneered by
Schmidpeter and co-workers. These species may be readily identified in solution by 31P NMR
spectroscopy. The crystal and molecular structures of five such derivatives have been ascertained for the
first time by single crystal X-ray diffraction at 120 K. The results confirm that normal single P–P bond
lengths are present in the dications, in contrast with the monocationic parent cyclic triphosphenium
ions, where structural determinations have shown that the P–P bond lengths are intermediate between
single and double bonds.
Schmidpeter and co-workers, who described the preparation of
two such compounds according to Scheme 2.12
Introduction
Cyclic triphosphenium ions, containing three linked phosphorus
atoms and a carbon backbone, were first prepared by Schmidpeter
et al. over twenty-five years ago.1 These interesting species have a
‘bare’ central P atom in the formal oxidation state of +1, and
may be readily identified in solution by 31P NMR spectroscopy.
Work in this area has been well-described in a recent review.2 In
structures that have been determined by X-ray diffraction, the
bond lengths are intermediate between normal P–P single and
double bonds,1–9 providing evidence for a delocalised system. The
presence of the ‘bare’ P in a low oxidation state should facilitate
oxidation reactions at this centre, and we have shown that direct
methylation using excess methyl triflate is possible for many of
these ions to form di-ium dications, as depicted in Scheme 1.10,11
Scheme 2 Indirect method of forming alkyl or aryl derivatives of cyclic
triphosphenium ions.12
To date no crystal or molecular structures of these dications
have been reported. In the present work, we show that a large
range of derivatives may be prepared via this alternative route,
indicating that the species are not intrinsically unstable. In all
examples, the 31P NMR solution-state parameters show a marked
reduction in 1JPP compared with the values for the triphosphenium
ions themselves. Five of these species have been isolated as salts,
and further characterised by single-crystal X-ray diffraction at low
temperature. In each instance the P–P distances are as expected
for single bonds, confirming that the central P is now in the +3
oxidation state, and that the delocalised double bond character
has been removed.
Scheme 1 Direct methylation of cyclic triphosphenium ions.
Attempts to extend this approach to larger organic substituents
on the attacking reagent have had only limited success, as described
below. We have carried out a few direct ethylations using excess
ethyl triflate, but only for small substituents on the two four-
coordinate P atoms, suggesting considerable steric hindrance
to the incoming reagent. This conclusion is supported by the
successful synthesis of several alkyl- and aryl-substituted cyclic
triphosphenium ions by an alternative route, again pioneered by
Results and discussion
A standardised numbering and lettering scheme has been adopted
for the cyclic triphosphenium ions and their derivatives described
in the present work. The parent diphosphanes are numbered
from 1–12 as shown in Scheme 3. The cyclic triphosphenium
ion corresponding to this diphosphane is taken as a, its P-methyl
derivative as b, P-ethyl as c, P-n-propyl as d, P-isopropyl as e,
P-tert-butyl as f, P-cyclohexyl as g and the P-phenyl derivative
as h.
Chemistry Department, University of Durham, South Road, Durham, UK
DH1 3LE. E-mail: k.b.dillon@durham.ac.uk; Fax: +44 (0)191 384 4737;
Tel: +44 (0)191 334 2092
† Dedicated to Professor Ken Wade, FRS, on the occasion of his 75th
birthday.
(a) Direct alkylation
‡ CCDC reference numbers 664568–664572. For crystallographic data in
CIF or other electronic format see DOI: 10.1039/b716027e
As described previously by us,10,11 direct methylation of several
cyclic triphosphenium ions by excess methyl triflate has proved
possible for ring sizes from 4–7 where the rings are sufficiently
§ Currently at: Department of Chemical Crystallography, Chemistry
Research Laboratory, University of Oxford, Oxford, UK OX1 3TA.
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the depe derivative did not lead to formation of the phenyl-
substituted dication, the solution-state spectrum showing only the
precursor ion, even though the dication may be readily prepared
by the alternative route described below. A similar experiment on
the seven-membered ring cyclic triphosphenium ion derived from
1,4-bis(diisopropyl)-phosphinobutane (dippb), in an attempt to
see whether a larger ring size would aid arylation, also failed to
produce the phenyl derivative.
The only report of direct alkylation before the studies mentioned
above was by Lochschmidt and Schmidpeter, who successfully
chloromethylated a dication to form a tetracation using a CH2Cl2–
AlCl3 mixture as the attacking reagent (Scheme 4).13 The combined
results indicate that direct alkylation is feasible for small organic
substituents on the attacking reagent, particularly Me, although
as pointed out previously, a large excess of methyl triflate is
often required, particularly if there are any other phosphorus
species in solution which would be more readily alkylated than
the triphosphenium ion.10,11
Scheme 3 Structures of the diphosphanes.
stable (Scheme 1). Some new 31P NMR results are shown in
Table 1, with the shifts and coupling constants of the precursor
triphosphenium ions included for comparison.
Scheme 4 Direct chloromethylation reaction.13
In all cases the most notable features are a large higher frequency
1
shift for the central P atom, and a marked reduction in JPP, on
methylation. The four-coordinate P atoms display a much smaller
shift to lower frequency in the alkyl derivatives.
(b) Indirect alkylation or arylation
Previous attempts at direct ethylation by excess ethyl triflate
had been unsuccessful,10 but this has now been achieved for
the five-membered ring cyclic triphosphenium ion derived from
depe, and the six-membered ring derived from depp. The results
are given in Table 2, and confirm the same trends in 31P NMR
data as described above for methylation. However, no direct
ethylations could be achieved for cyclic triphosphenium ions with
cyclohexyl, phenyl, isopropyl or tert-butyl substituents on the
outer phosphorus atoms, strongly suggesting considerable steric
hindrance to the formation of the ethyl derivatives. Ethylation is
expected to occur for the ion derived from dmpe, but the reaction
products proved to be too insoluble for a solution-state spectrum
to be obtained. Similarly, reaction of excess phenyl triflate with
Indirect alkylation or arylation involves the treatment of a
diphosphane R2P(CH2)nPR2 with a dichlorophosphane RꢀPCl2
(1:1) inthe presenceoftwomoles ofAlCl3, as shown in Scheme2.12
We have prepared the complete series of such derivatives in
solution for Rꢀ = Et, n-Pr, i-Pr, t-Bu, c-Hex or Ph with the
diphosphanes depe (1) and dppe (6); the 31P NMR data are listed
in Tables 3 and 4 respectively.
Two sets of resonances were observed for the cyclohexyl
derivative of the ring formed from dppe, ascribed to a mixture
−
of Cl− and AlCl4 counter-ions. Their identities were established
by adding more AlCl3 to the mixture, which caused an increase in
relative intensity for the signals at 48.9 and −75.7 ppm, so these
−
may be assigned to the bis-AlCl4 salt.
Table 1 31P NMR data (d in ppm; 1JPP in Hz) for some cyclic triphosphenium ions and their P-methyl derivatives
Compound
Ion
Ring size
dPB
dPA
1JPP
Ion
dPD
dPC
1JPP
1
2
3
4
5
1a
2a
3a
4a
5a
5
5
6
6
7
81.7
87.3
33.4
36.2
48.1
−269.2
−289.3
−251.3
−293.0
−261.4
441
457
415
458
475
1b
2b
3b
4b
5b
65.7
65.1
28.1
27.0
43.4
−98.0
289
301
274
281
321
−96.1
−102.1
−109.5
−76.3
Table 2 31P NMR data (d in ppm; 1JPP in Hz) for some cyclic triphosphenium ions and their P-ethyl derivatives
Compound
Ion
Ring size
dPB
dPA
1JPP
Ion
dPD
dPC
1JPP
1
3
1a
3a
5
6
81.7
30.0
−269.2
−251.3
441
418
1c
3c
66.1
28.6
−89.8
−89.8
291
283
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1
Table 3 31P NMR data (d in ppm; JPP in Hz) for some alkyl and aryl
Table 5 31P NMR data (d in ppm; 1JPP in Hz) for other ethyl derivatives
of cyclic triphosphenium ions
derivatives of depe, 1
Substituent
Code
dPD
dPC
1JPP
Diphosphane Code Compound Ring size dPD
dPC
1JPP
Et
1c
1d
1e
1f
1g
1h
66.0
62.2
67.3
66.8
67.0
60.2
−92.7
−95.1
−66.6
−33.6
−71.9
−94.2
293
295
311
338
309
280
dcxpm
dcxpea
dppE
7
7c
4
5
5
5
5
5
6
6
7
7
40.4 −59.7 156
57.0 −85.2 319
58.9 −93.2 307
46.6 −76.4 290
44.8 −66.7 286
45.1 −72.2 300
28.9 −85.8 301
28.7 −92.4 303
32.1 −52.6 305
12.8 −14.2 322
n-Pr
i-Pr
t-Bu
c-Hex
Ph
2
2c
8
9
10
10
3
4
5
11
8c
9c
10c
10c
3c
4c
5c
11c
dmpe
dppben
dppbena
depp
dcxpp
dcxpba
biphep
Table 4 31P NMR data (d in ppm; JPP in Hz) for some alkyl and aryl
derivatives of dppe, 6
1
a SnCl2 added instead of AlCl3.
Substituent
Code
dPD
dPC
1JPP
Et
n-Pr
i-Pr
t-Bu
c-Hex
6c
6d
6e
6f
53.4
53.8
49.0
49.5
50.4
48.9
53.1
−93.0
−95.1
−71.3
−54.0
−79.1
−75.7
−76.9
287
288
304
332
311
308
280
may be compared with those previously reported by us for the
methyl (7b) derivative, prepared by direct methylation of the
cyclic triphosphenium ion 7a.11 These ions have the smallest 1JPP
values yet measured in such systems, parallel with data for 7a
6g
1
itself, which has the smallest JPP value for such a species. Thus
Ph
6h
the changes caused by alkylation are not out of line with the
results for larger-ring systems. The results for 6b and 8b are
very similar to those obtained previously for these ions by direct
methylation,10 particularly when the difference in counter-ion is
taken into account.
The mechanism of this indirect alkylation (or arylation) reaction
necessarily involves the addition of the chlorophosphane to one of
the P atoms of the diphosphane to form a P–P bond, as shown in
Scheme 5. This is expected to displace a halogen, accepted by AlCl3
to form a tetrachloroaluminate, as shown. Cyclisation with loss of
the second halogen (in the presence of AlCl3) to yield the dicationic
product then follows, Scheme 5. It should be noted that the acyclic
cationic intermediate is identical to that postulated in the first
For all ions in both series there is a marked reduction in
1JPP compared with the triphosphenium ions 1a (Table 1) or 6a1
respectively, and a large shift to higher frequency of the central
phosphorus atom. The four-coordinate P atoms give a much
smaller shift to lower frequency on alkylation. In these two series,
1JPP values are very similar for Rꢀ = Et or n-Pr, though there
is then a significant increase on going from n-Pr to i-Pr to t-Bu
substituents.
Our results for the t-butyl derivative of the dppe system differ
from those of Schmidpeter et al., who reported dPD 52, dPC
1
−79 ppm, JPP 283 Hz.12 The present data are much more
consistent with the results for the depe series, and it seems
probable that under their experimental conditions they obtained
1
the chloromethyl derivative (dPD 52, dPC −78 ppm, JPP 282 Hz)
described in the same paper,12 with this species being formed in
preference to the t-Bu analogue.
The ethyl derivatives of a number of other cyclic triphosphenium
ions have also been synthesised in solution; the 31P NMR results
are presented in Table 5, for various ring sizes as indicated.
Table 6 gives parallel results for some other dihalophosphanes.
Particularly noteworthy are the results for the four-membered
ring dcxpm system with ethyl (7c, Table 5) or isopropyl (7e,
Table 6) substituents. The reaction with i-PrPCl2 was performed
in the presence of both AlCl3 and SnCl2 separately; very similar
results were obtained, as shown in Table 6. The NMR parameters
Scheme 5 Mechanism of indirect alkylation or arylation reactions.
Table 6 31P NMR data (d in ppm; 1JPP in Hz) for other alkyl or aryl derivatives of cyclic triphosphenium ions
Diphosphane
Code
Rꢀ
Code
Ring size
dPD
dPC
1JPP
dcxpma
dcxpmb
dppe
dppE
depp
7
i-Pr
i-Pr
Me
Me
n-Pr
Ph
7e
4
4
5
5
6
6
6
38.8
38.8
53.2
59.8
30.0
27.8
37.2
−29.1
−28.9
−96.9
−97.0
−89.1
−83.7
−92.8
152
150
279
301
306
295
288
7
7e
6
6b
8b
3d
3h
12d
8
3
depp
dippp
3
12
n-Pr
a AlCl3 added. b SnCl2 added.
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1
Table 7 31P NMR data (d in ppm; JPP in Hz) for intermediates in
Table 8 Selected inter-atomic distances and angles
attempted indirect alkylations
Compound
P–P/A
P–P–P/◦
P –C/A
a
˚
˚
Diphosphane
Code
Rꢀ
dPE
dPF
dPG
1JPP
1c
1d
6c
2.2327(9)
2.2302(8)
2.225(3)
2.218(3)
2.231(3)
2.214(3)
2.2108(9)
2.2105(8)
2.201(3)
2.203(3)
2.220(3)
2.197(4)
90.30(3)
90.06(3)
89.17(12)
89.41(11)
86.09(11)
96.59(13)
1.864(3)
1.867(2)
1.848(10)
1.867(9)
1.880(8)
1.867(9)
depp
depp
depp
dcxpp
dippp
3
Et
17.4
18.2
17.5
11.7
33.3
57.2
57.3
57.2
50.4
60.1
−48.1
−48.3
−48.2
−28.8
−26.4
278
278
279
309
309
3
i-Pr
t-Bu
n-Pr
t-Bu
3
4
12
6e
11c
a Central P, shown as PC in Scheme 5.
stage of formation of the novel cyclic tetraphosphonium dications,
described very recently by us.14 In the present case, however, no
redox step is involved, although the reaction will undoubtedly
be facilitated by the presence of a good halide acceptor. Indeed,
as we have demonstrated in a previous paper,14 a mixture of
the triphosphane-di-ium dication and tetraphosphonium dication
(4P) is often obtained when a diphosphane is treated with RꢀPCl2
in the presence of SnCl2. In some slowly-reacting systems, NMR
spectroscopic evidence for the acyclic intermediate was found. This
1
species is expected to give rise to two doublets with a large JPP
for PF and PG (Scheme 5), and either a singlet for PE, or a doublet
with a much smaller coupling constant from PF coupling. In this
case PF should also show fine structure (as a doublet of doublets).
Weak signals were detected for depp reacting with EtPCl2 (Table 7)
in the process of forming 3c, which could be assigned to PE, PF
and PG (Scheme 5), in the acyclic intermediate. Interestingly, 31P
NMR signals for similar intermediates were also observed for the
reaction of depp 3 with both i-PrCl2 and t-BuPCl2, of dcxpp 4
with n-PrPCl2, and of dippp 12 with t-BuPCl2. In these systems,
however, the cyclic product was not detected. The NMR data
are given in Table 7. As all of these reactions involved quite
bulky substituents on either the diphosphane and/or RꢀPCl2, it
seems probable that steric hindrance can prevent ring formation
in unfavourable cases.
Fig. 2 The molecular structure of the dication 1d (the counter-ions have
been omitted for clarity). Thermal ellipsoids are drawn at 50% probability.
Very similar parameters are obtained for 1d; the P–P bond lengths
◦
˚
are 2.2105(8) and 2.2302(8) A, while the P–P–P angle is 90.06(3) .
In 6c, both counter-ions are AlCl4−; its molecular structure is
shown in Fig. 3. The P–P distances are very similar, at 2.201(3)–
˚
2.225(3) A, and the P–P–P angles are slightly smaller at 89.17(12)
and 89.41(11)◦ (Table 8). The crystals of 6e were obtained from
a reaction carried out with SnCl2 rather than AlCl3 present,
Five of the compounds, 1c, 1d, 6c, 6e and 11c, have been isolated
as solids, and their crystal and molecular structures have been
determined at 120 K. The molecular structures of 1c and 1d are
shown in Fig. 1 and 2 respectively. In both cases, the counter-ions
to the dication are one Cl− and one AlCl4−. Selected bond distances
and angles for all the new structures are listed in Table 8. The
most significant bond lengths in 1c are the P–P distances, which
2−
the counter-ion being SnCl6 in this complex (Fig. 4). In these
crystals there are also two CDCl3 molecules of crystallisation. The
2−
SnCl6 ion is not expected to form during the synthesis of 6e
itself, but from a parallel reaction leading to the 4P derivative,14
as mentioned earlier. In this structure, one of the carbon atoms
linking the two PPh2 groups, one of the P atoms coordinated
to it and one of the phenyl groups attached to the latter were
disordered over two positions, with refined occupancies of 89.2(7)
˚
are 2.2108(9) and 2.2327(9) A. These values, as expected, lie in the
range for normal P–P single bonds. The P–P–P angle is 90.30(3)◦.
Fig. 1 The molecular structure of the dication 1c, showing the numbering
scheme for the key atoms (the counter-ions have been omitted for clarity).
Thermal ellipsoids are drawn at 50% probability.
Fig. 3 The molecular structure of the dication 6c (only one dication
is shown and the counter-ions have been omitted for clarity). Thermal
ellipsoids are drawn at 50% probability.
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Conclusions
We therefore conclude that many examples of the di-ium dications
should be preparable, although the scope for direct attack on the
central phosphorus atom of a cyclic triphosphenium ion seems
quite limited, because of steric constraints. It may also be difficult
for cyclisation to occur in the alternative synthetic route when
both Rꢀ and R are bulky. The ions seem quite stable once formed,
and X-ray crystallographic studies have confirmed the presence of
P–P single bonds with the change of formal oxidation state of the
central atom from P(I) to P(III).
Experimental
Fig. 4 The molecular structure of the dication 6e (the counter-ion,
disordered component and solvent molecules have been omitted for
clarity). Thermal ellipsoids are drawn at 50% probability.
All manipulations, including NMR sample preparation, were
carried out either under an inert atmosphere of dry nitrogen or
in vacuo, using standard Schlenk line or glovebox techniques.
Chemicals of the best available commercial grade were used, in
general without further purification. The 31P NMR spectra of
all phosphorus-containing starting materials were recorded, to
verify that no major impurities were present. 31P NMR spectra
were obtained on Varian Unity 300, Mercury 400 or Inova 500
Fourier-transform spectrometers at 121.40, 161.91 or 202.3 MHz
respectively; chemical shifts are referenced to 85% H3PO4, with
the high frequency direction taken as positive.
and 10.8(7)% respectively (see the Experimental section). The P–P
˚
bond distances of 2.231(3) and 2.220(3) A in the major component
are again entirely commensurate with P–P single bonds. The P–
P–P bond angle is rather smaller at 86.09(11)◦, probably because
of the steric effect of the larger i-Pr instead of an Et group on the
central phosphorus atom. The molecular structure of compound
11c, with a seven-membered ring, is shown in Fig. 5. The counter-
ion in this salt is SnCl62−. The bond lengths of 2.214(3) and
˚
Direct methylations using excess methyl triflate were carried
out as described previously.10,11 For the direct ethylation reactions,
the cyclic triphosphenium ion 1a was prepared in CDCl3 solution
from depe 1 (0.0959 g, 0.46 mmol) and PCl3 (0.03 ml, 0.31 mmol);
after verification that the ion 1a had formed, ethyl triflate (0.08 ml,
0.62 mmol) was added by syringe. Cyclic triphosphenium ion 3a
was similarly prepared from depp 3 (0.0955 g, 0.43 mmol) and
PCl3 (0.03 ml, 0.31 mmol); after formation of 3a, excess ethyl
triflate (0.12 ml, 0.93 mmol) was added. The indirect alkylations or
arylations were performed by mixing solutions of the diphosphane,
the dichlorophosphane and AlCl3 or SnCl2 in CDCl3 as solvent.
In a typical preparation of 7e, solutions of dcxpm 7 (0.0369 g,
0.09 mmol), i-PrPCl2 (0.02 ml, 0.16 mmol) and AlCl3 (0.0240 g,
0.18 mmol) were mixed. The same dication 7e was prepared
in the presence of SnCl2 from solutions of dcxpm 7 (0.0319 g,
0.08 mmol), i-PrPCl2 (0.02 ml, 0.16 mmol) and SnCl2 (0.0303 g,
0.16 mmol) in CDCl3. All other compounds were prepared in a
similar manner. Some of the solution in each case was set aside
in a crystal tube to see whether crystals would form. Crystals
suitable for X-ray diffraction were obtained from solutions of 1c,
1d and 6c where AlCl3 was used as the chloride acceptor, while
crystals of 6e and 11c were obtained as hexachlorostannate(IV)
salts from similar reactions with SnCl2 present. The formation of
a tin(IV) species showed that a redox reaction, probably leading to a
tetraphosphonium dication (4P)14, had occurred in these systems.
2.197(4) A again correspond to P–P single bonds; the P–P–P bond
angle of 96.59(13)◦ reflects the difference in ring size from the
other four structures.
Fig. 5 The molecular structure of the dication 11c (the counter-ions and
solvent molecules have been omitted for clarity). Thermal ellipsoids are
drawn at 50% probability.
In all of the cyclic triphosphenium ions which have been
structurally characterised, the P–P distances lie between 2.1172(7)
and 2.135(2) A, attributed to a delocalised system, and a bond
˚
order higher than one for both P–P bonds.1–9 This possibility is
removed by oxidation, and the bond lengths in the di-ium dications
are exactly as expected for single P–P bonds. We predict with some
confidence that further structural studies on cyclic triphosphenium
ions and on their alkyl- or aryl-substituted derivatives will give
comparable results to those obtained in previous studies for the
former, and in the present work for the latter, with a likely range
X-Ray crystallography
Single crystal structure determinations were carried out from
data collected using graphite monochromated Mo-Ka radiation
˚
(k = 0.71073 A) on a Bruker SMART-CCD 1K diffractometer at
120 K. The temperature was controlled using a Cryostream N2 flow
cooling device.15 In each case, series of narrow x-scans (0.3 ◦) were
performed at several φ-settings in such a way as to cover a sphere
˚
between 2.19 and 2.24 A for the single-bonded systems.
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˚
7314/61/442 (Rint = 0.0813), final R1 = 0.0671, wR2 = 0.1362
(I>2r(I)).
of data to a maximum resolution of 0.70 A. Cell parameters were
determined and refined using SMART software,16 and raw frame
data were integrated using the SAINT program.17 The structures
were solved using direct methods,18 and refined by full-matrix
least-squares on F2 using SHELXL-9719 and the graphical user
interface Olex220 or CRYSTALS.21 For 6c reflection intensities
were corrected by numerical integration based on measurements
and indexing of the crystal faces using the SHELXTL software.22
In the remaining cases, intensities were corrected for absorption
effects by the multi-scan method, based on multiple scans of
identical and Laue equivalent reflections (using the SADABS
software).23 In general, non-hydrogen atoms were refined with
anisotropic displacement parameters and hydrogen atoms were
positioned geometrically and refined using a riding model. In the
structure of 6e, restraints were necessary during the refinement
of one of the C–PPh2 moieties. The carbon atom, the P atom
coordinated to it and one of its attached phenyl rings were
modelled as disordered over two positions (refined occupancies
of 89.2(7) and 10.8(7)% respectively). Each pair of disordered
atoms was constrained to have the same displacement parameters.
Distances between equivalent atoms in the disordered section with
lower occupancy were restrained to be the same as those from
the fragment with higher occupancy. In addition, the anisotropic
displacement parameters of all carbon atoms belonging to the
phenyl rings were subject to a ‘rigid body’ restraint. The distance
between P1 and the minor component P3A was restrained to a
sensible distance. The diffraction data for 11c were also of poor
quality, so similar-ADP and rigid bond restraints were used to
maintain sensible geometries.
¯
Single crystal data for 11c. Mr = 1152.68, triclinic, P1, Z =
˚
˚
˚
˚
2, a = 10.7742(10) A, b = 11.4878(10) A, c = 19.2490(17) A,
◦
◦
◦
a = 89.558(2) , b = 82.088(2) , c = 82.033(2) , V = 2336.9(4) A,
Data/restraints/parameters 9111/299/509 (Rint = 0.1124), final
R1 = 0.0908, wR2 = 0.1284 (I>2r(I)).
Acknowledgements
We would like to thank the EPSRC for a postgraduate fellowship
(to ALT), for a research studentship (to HJS), and the Maria da
Grac¸a Memorial Studentship/Chemistry Department, University
of Durham, for financial support (to PKM).
References
1 A. Schmidpeter, S. Lochschmidt and W. S. Sheldrick, Angew. Chem.,
Int. Ed. Engl., 1982, 21, 63.
2 B. D. Ellis and C. L. B. Macdonald, Coord. Chem. Rev., 2007, 251, 936.
3 J. A. Boon, H. L. Byers, K. B. Dillon, A. E. Goeta and D. A.
Longbottom, Heteroat. Chem., 2000, 11, 226.
4 R. J. Barnham, R. M. K. Deng, K. B. Dillon, A. E. Goeta, J. A. K.
Howard and H. Puschmann, Heteroat. Chem., 2001, 12, 501.
5 B. D. Ellis, M. Carlesimo and C. L. B. Macdonald, Chem. Commun.,
2003, 1946.
6 R. M. K. Deng, A. E. Goeta, K. B. Dillon and A. L. Thompson, Acta
Crystallogr., Sect. E, 2005, 61, m296.
7 R. Kilian, A. M. Z. Slawin and J. D. Woollins, Dalton Trans., 2006,
2175.
8 B. D. Ellis and C. L. B. Macdonald, Inorg. Chem., 2006, 45, 6864.
9 B. D. Ellis and C. L. B. Macdonald, Acta Crystallogr., Sect. E, 2006,
62, m1235.
10 K. B. Dillon and R. J. Olivey, Heteroat. Chem., 2004, 15, 150.
11 K. B. Dillon, P. K. Monks, R. J. Olivey and H. H. Karsch, Heteroat.
Chem., 2004, 15, 464.
12 A. Schmidpeter, S. Lochschmidt, K. Karaghiosoff and W. S. Sheldrick,
J. Chem. Soc., Chem. Commun., 1985, 1447.
13 S. Lochschmidt and A. Schmidpeter, Z. Naturforsch., B: Anorg. Chem.,
Org. Chem., 1985, 40, 765.
Single crystal data for 1c. Mr = 470.49, monoclinic, Cc,
˚
˚
˚
Z = 4, a = 10.1314(4) A, b = 25.1148(11) A, c = 8.8636(4) A,
◦
˚
b = 90.957(1) , V = 2255.01(17) A, data/restraints/parameters
5601/2/196 (Rint = 0.0266), final R1 = 0.0359, wR2 = 0.0789
(I>2r(I)).
14 A. J. Boyall, K. B. Dillon, J. A. K. Howard, P. K. Monks and A. L.
Thompson, Dalton Trans., 2007, 1374.
15 J. Cosier and A. M. Glazer, J. Appl. Crystallogr., 1986, 19, 105.
16 SMART-NT, Data Collection Software, version 6.1, Bruker Analytical
X-ray Instruments Inc., Madison, WI, USA, 2000.
Single crystal data for 1d. Mr = 484.52, monoclinic, Cc,
˚
˚
˚
Z = 4, a = 10.3722(3) A, b = 25.1650(8) A, c = 8.8229(3) A,
◦
˚
b = 90.502(1) , V = 2302.83(13) A, data/restraints/parameters
7542/2/205 (Rint = 0.0302), final R1 = 0.0331, wR2 = 0.0742
(I>2r(I)).
17 SAINT-NT, Data Reduction Software, version 6.1, Bruker Analytical
X-ray Instruments Inc., Madison, WI, USA, 2000.
18 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
19 G. M. Sheldrick, SHELXL-97, Program for refinement of crystal
structures, University of Go¨ttingen, Germany, 1997.
20 O. Dolomanov and H. Puschmann, Olex2, University of Durham,
2007, unpublished work.
21 P. W. Betteridge, J. R. Carruthers, R. I. Cooper, C. K. Prout and D. J.
Watkin, J. Appl. Crystallogr., 2003, 36, 1487.
22 G. M. Sheldrick, SHELXTL, version 6.1, Bruker Analytical X-ray
Instruments Inc., Madison, WI, USA, 1999.
23 G. M. Sheldrick, SADABS, University of Go¨ttingen, Germany1998.
Single crystal data for 6c. Mr = 796.05, orthorhombic, Pba2,
˚
˚
˚
Z = 4, a = 22.8830(16) A, b = 31.806(2) A, c = 9.8121(7) A,
˚
V = 7141.4(8) A, data/restraints/parameters 14723/1/741 (Rint
=
0.098), final R1 = 0.0695, wR2 = 0.1120 (I>2r(I)).
Single crystal data for 6e. Mr = 1042.57, monoclinic, P21/n,
˚
˚
˚
Z = 4, a = 12.7862(8) A, b = 21.2600(14) A, c = 15.2904(10) A,
◦
˚
b = 94.661(1) , V = 4142.7(5) A, data/restraints/parameters
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