1-Triphenylstannyl-2,4,5-tritertiarybutyl-1,3-diphosphole, Ph 3SnP2C3Bu3t: Preparation, X-ray crystal structure, theoretical studies and solution fluxional behaviour

Article abstract of DOI:10.1016/j.jorganchem.2005.05.046

The 1-triphenylstannyl-2, 4, 5-tritertiarybutyl-1,3-diphosphole, Ph3SnP2C3Bu3t, which has been synthesised from Ph₃SnCl and KP2C3Bu3t, has been fully structurally characterised in the solid state but in solution undergoes ready intra-molecular

Full text of DOI:10.1016/j.jorganchem.2005.05.046

Journal of Organometallic Chemistry 690 (2005) 3983–3989
www.elsevier.com/locate/jorganchem
1-Triphenylstannyl-2,4,5-tritertiarybutyl-1,3-diphosphole,
Ph3SnP2C3But3: Preparation, X-ray crystal structure,
theoretical studies and solution fluxional behaviour
F. Geoffrey , N. Cloke ,a, Peter B. Hitchcock , John F. Nixon
,
a
a
a,
*
*
a
D. James Wilson , Laszlo Nyulaszi , Tamas Karpati
,b
b
*
´
´
´
´
´ ´
a
Chemistry Department, School of Life Sciences, University of Sussex, Brighton BN1 9QJ, Sussex, UK
´ ´
Department of Inorganic Chemistry, Technical University of Budapest, H-1521 Budapest Gellert ter 4, Hungary
b
Received 17 May 2005; received in revised form 17 May 2005; accepted 26 May 2005
Available online 11 July 2005
Abstract
The 1-triphenylstannyl-2, 4, 5-tritertiarybutyl-1,3-diphosphole, Ph3SnP2C3But3, which has been synthesised from Ph3SnCl and
KP2C3But3, has been fully structurally characterised in the solid state but in solution undergoes ready intra-molecular shifts of
the Ph3Sn-group around the 1,3-diphospholyl ring. Theoretical calculations concerning both the structure and the dynamic process
are presented and discussed.
ꢀ 2005 Elsevier B.V. All rights reserved.
1. Introduction
We therefore considered the possibility of using an
organostannyl derivative of the P2C3But3 diphospholyl
ring system as an alternative synthetic approach, since
the corresponding organostannyl cyclopentadiene,
R3SnC5H4, systems are well known ring transfer re-
agents, [5] and are readily prepared from the organo-
tin(IV) halides, R3SnX, and the corresponding C5H5
ring anion. Furthermore, Nief and Mathey [6] have uti-
lised 1-trimethylstannyl phospholyl derivatives, such
as Me3SnPC5R4 for the preparation of a variety of
g5-complexes of the early transition metals typified
by [TiCl3(g5-PC5R)4], [TiCl2(g5-C5R5)(PC5R4)] and
[TiCl2(g5-PC5R4)2] (R = H or Me).
Recently [1] we described the synthesis of the 5-mem-
bered aromatic 1,3-diphospholyl ring anion P2C3Bu3tꢀ
via an unusual ring contraction reaction involving treat-
ment of the neutral 6-membered aromatic 1,3,5-triphos-
phabenzene ring, P3C3Bu3t , with potassium (see Fig. 1).
In subsequent unpublished work [2] we have success-
fully utilised the resulting KðTHFÞðP2C3But3Þ salt in the
efficient synthesis of the triad of Group 10 transition me-
tal complexes of the type ½MðP2C3But3Þ ꢁ, (M = Ni, Pd,
2
Pt), by treatment with the corresponding metal dichlo-
ride. However, the corresponding reactions with each
of the Group 4 transition metal tetrachlorides did not
lead to the expected metallocene dichlorides
The NMR spectroscopically characterised 1-stannyl-
1,2,4-triphospholes R3SnP3C2But2 (R = Me, Ph), were
synthesised in our laboratory from NaP3C2But2 and
R3SnCl, (R = Me, Ph) [7], and also by Zenneck and
co-workers [8–13], in a much more comprehensive series
of studies. They fully structurally characterised the latter
and demonstrated its utility as a ring transfer reagent
through the reactions with SnCl2 generating the
½Mðg5-P2C3Bu3t Þ Cl2ꢁ, (M = Ti, Zr Hf) [3], but instead
2
only resulted in oxidative coupling of the ring anions,
yielding the known orange crystalline diphospholyl di-
mer, P4C6But6 [4], as the sole product (see Fig. 2).
*
Corresponding author.
E-mail address: j.nixon@sussex.ac.uk (J.F. Nixon).
hexaphospha-stannocene ½Snðg5-P3C2Bu2t Þ ꢁ and also
2
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.05.046

3984
F. Geoffrey et al. / Journal of Organometallic Chemistry 690 (2005) 3983–3989
But
The structure of (1a) consists of a Ph3Sn-fragment r-
But
K
THF
But
P
bonded to an essentially planar C(1)–P(2)–C(2)–C(3)–
P(1) fragment (RMS deviation of the least squares plane
formed by C(1)–P(2)–C(2)–C(3)–P(1) = 0.0074). The 1-
stannyldiphosphole intra-ring bond distances imply
rather localised double bonds between C(3) and C(2)
K+(THF)
But
+ K3P
P
P
P
P
But
But
Fig. 1.
˚
˚
(1.389(4) A) and between C(1)and P(2) (1.690(3) A)
which are, as expected, both shorter than those found
in the fully delocalised p-system of the parent diphos-
t
t
Bu
t
Bu
P
Bu
t
tꢀ
Bu
˚
pholyl ring anion, P2C3Bu3 , (1.416(6) and 1.777(5) A,
respectively) [1]. The distance between C(1) and P(1)
P
THF
P
P
+
P
K (THF)
+
t
ZrCl
4
P
˚
(1.779 A), however, is somewhat shorter than a localised
t
Bu
t
t
t
Bu
Bu
˚
single bond distance which is usually greater than 1.80 A.
Bu
Bu
˚
The Sn atom in (1a) lies 2.48 A out of the plane
Fig. 2.
formed by the C(1)–P(2)–C(2)–C(3)–P(1) fragment of
the diphosphole ring, and the sum of the angles around
P(1) indicates strong pyramidal character, with an out
of plane lone electron pair (R angles at P(1) = 293.42ꢁ).
In the case of the 1-triphenylstannyl-1,2,4-triphosphole
Ph3SnP3C2But2 a similar strongly pyramidalised satu-
rated phosphorus was observed in the non-planar ring,
described the further synthetic potential of both the
1-triphenylstannyl and 1-trimethylstannyl 1,2,4-tri-
phospholyl compounds in the synthesis of a variety of
1,2,4-triphospholyl transition metal derivatives of Co,
Mn, Ni and Au.
˚
the Sn bonded phosphorus being located 0.227(5) A
out of the best plane of the ring [11] and the sum of the
angles at this saturated phosphorus centre is slightly
greater (300.26ꢁ). Both values are in sharp contrast to
those observed in our previously described P-substituted
1,2,4-triphospholes (Me3Si)2CHP3C2(SiMe3)2 (X), which
contains a completely planar saturated 3-coordinate
2. Results and discussion
Treatment of KðTHFÞðP2C3But3Þ with Ph3SnCl
yielded the 1-triphenylstannyl-2,4,5-tritertiarybutyl-1,3-
diphosphole Ph3SnP2C3But3 (1a) as a yellow powder.
Crystals suitable for X-ray analysis were grown from a
saturated slowly cooled hexane solution and the molec-
ular structure is displayed below in Fig. 3, together with
relevant bond length and bond angle data.
phosphorus centre [14], and in ðMe3SiÞ CHP3C2Bu2t
2
(Y) [15], where the sum of the angles at the saturated
phosphorus atom is 342.0ꢁ. Compound (1a) represents
the first example of a structurally characterised g1-
ligated P2C3But3 ring system, although analogous
compounds of the related P3C2But2 anion are well
known.
P
P
But
SiMe3
But
Me3Si
Me3Si
P
P
P
P
HC
CH
SiMe3
Me3Si
SiMe3
Y
X
We have shown elsewhere [16,17] that the aromaticity
in the phosphole–pentaphosphole series becomes greater
with increasing number of phosphorus atoms in the
ring. Furthermore, the presence of the stannyl group
on a saturated carbon was shown to substantially in-
crease the aromaticity in cyclopentadiene [18]. In the
light of these previous results the nearly unchanged
(approximately 300ꢁ) bond angle sums at the saturated
phosphorus atom of the stannyl substituted di- and tri-
phospholes needs further theoretical investigation.
Fig. 3. Molecular structure of Ph3SnP2C3But3 (1a). Selected bond
˚
lengths (A), and angles (ꢁ): C(1)–P(2) 1.690(3), P(2)–C(2) 1.817(3),
C(2)–C(3) 1.389(4), P(1)–C(3) 1.817(3), C(1)–P(1) 1.779(3), Sn–P(1)
2.5456(9); P(1)–Sn–C(28) 113.18(9), P(1)–Sn–C(28), C(28)–Sn–C(22),
C(22)–Sn–C(16), C(1)–P(1)–C(3) 99.44(14), C(1)–P(1)–Sn 97.68(10),
Sn–P(1)–C(3) 97.30(10). Hydrogen atoms are omitted for clarity.
Thermal ellipsoids are shown at the 50% probability level.

F. Geoffrey et al. / Journal of Organometallic Chemistry 690 (2005) 3983–3989
3985
B3LYP/LANL2DZ( ) theoretical calculations sup-
*
port the non- planarity of the 1-stannyldiphosphole ring
(1a) and calculations starting from an initial planar
geometry show that the Ph3Sn-group moves to a non-
planar position. The calculated bond angle sum about
phosphorus is 307ꢁ, which is somewhat larger than in
the X-ray structure, however the calculated bond lengths
match favourably with the X-ray data (see Table 1).
With the less bulky trimethylstannyl substituent the
bond angle sum is less than 300ꢁ, which is somewhat
smaller than for the parent 1,3-diphosphole (301ꢁ). Since
the degree of pyramidalisation at phosphorus is usually
related to aromaticity in phospholes [16,17], the aroma-
ticity measures of 1a were compared to those of the
parent 1,3-diphosphole The Bird index of 1a was 51
(1,3-diphosphole 50) and the NICS(0) value for 1a was
ꢀ5.9 ppm (1,3-diphosphole ꢀ5.9 ppm) indicating that
there is no significant change in the aromaticity of the
ring upon stannyl substitution.
The effect of the stannyl group can be best under-
stood by investigating the phosphorus non-bonding
(HOMO ꢀ 1) orbital [19], which is shown for the parent
1,3-diphosphole and for its trimethylstannyl derivative
in Fig. 4.
In the case of the parent 1,3-diphosphole both the
p-system (at the carbon atoms) and the in-plane phos-
phorus lone pair contribute to the orbital. (Note that
the s-type lone pair at the tri-coordinate phosphorus is
situated out of the plane of the five ring atoms, and its
antibonding combination with the in-plane lone pair
of the phosphorus at the 3 position of the ring has the
proper symmetry to overlap somewhat with the p-
system.) As the number of phosphorus atoms in the ring
increases, the tri-coordinate phosphorus flattens thereby
allowing its pZ orbital to overlap better with the p-
Fig. 4. HOMO ꢀ 1 phosphorus lone pair MOs of 1,3-diphosphole and
its trimethylstannyl derivative.
system [17]. Stannyl substitution at the tri-coordinate
phosphorus results in a significant perturbation of
the phosphorus lone pair orbital as shown in Fig. 5. The
rPSn bonding orbital which is close in energy to the
phosphorus lone pair (unlike rPC which is more stable)
interacts strongly, the resulting antibonding combina-
tion having similar symmetry to a pZ type orbital. This
orbital has the proper symmetry to overlap with the p-
system and thus stannyl substitution at phosphorus al-
lows an interaction between both the phosphorus lone
pair and.the p-system, even with the pyramidal arrange-
ment of phosphorus.
3. Dynamic behaviour of Ph3SnP2C3But3 (1a)
The 31P{1H} NMR spectrum of Ph3SnP2C3But3 (1a)
acquired at ambient temperature displayed two very
broad resonances (d 315, 25 ppm; m1/2 = 3000 Hz) and
Table 1
B3LYP/LANL2DZ + P structural parameters and aromaticity measures of the investigated compounds QPCRPCRCR
Q
R
Isomer
a
b
c
d
e
RP
(ꢁ)
Bird
NICS
(ppm)
ꢀ5.85
NICS1
˚
(A)
˚
(A)
˚
(A)
˚
(A)
˚
(A)
(ppm)
SnPh3
t-Bu
1
2
3
1.790
1.813
1.713
1.710
1.817
1.772
1.833
1.757
1.752
1.394
1.455
1.497
1.849
1.757
1.871
307.1
46
74
43
ꢀ5.23, ꢀ7.56
–
–
SnMe3
SnMe3
SnMe3
H
t-Bu
Me
H
1
2
3
1.790
1.813
1.717
1.711
1.812
1.770
1.833
1.757
1.755
1.395
1.457
1.491
1.844
1.757
1.869
296.9
48
75
46
–
–
1
2
3
1.800
1.823
1.725
1.718
1.822
1.786
1.809
1.740
1.739
1.376
1.428
1.459
1.810
1.740
1.843
294.1
56
64
58
–
–
1
2
3
1.787
1.821
1.781
1.716
1.821
1.719
1.801
1.731
1.824
1.373
1.419
1.454
1.796
1.731
1.727
293.9
61
61
61
–
–
H
1
2
3
1.795
1.866
1.695
1.703
1.866
1.817
1.820
1.708
1.674
1.363
1.442
1.498
1.804
1.708
1.869
300.7
50
30
26
ꢀ5.86
ꢀ4.97
ꢀ3.87
ꢀ7.05, ꢀ7.80
ꢀ7.06
–
–
ꢀ6.75

3986
F. Geoffrey et al. / Journal of Organometallic Chemistry 690 (2005) 3983–3989
The low temperature limiting spectrum of the
119Sn{1H} variable temperature NMR spectroscopic
analysis, shown below in Fig. 6, displayed the pattern
of lines expected for the [ABX] spin system (d
ꢀ146.2 ppm, dd, J(PSn) 700.7 Hz; J(PP) 124.6 Hz) in
the chemical shift region for four coordinate Sn(IV)
while the magnitude of 1J(PSn) compares favourably
with the average value deduced from the low tempera-
ture 31P{1H} NMR spectrum. Elevation of the tempera-
ture results in the collapse of the outer two signals of the
[ABX] spin system resonances and the appearance of a
E
Sn
P
1
3
Sn
P
ox
Sn
P
ox
ox
Sn
Sn
P
P
ox
Sn
P
Fig. 5. Orbital interaction scheme between the P–Sn bonding (and
antibonding) orbital(s) and the phosphorus lone pair.
that observed at 383 K showed a single resonance at an
average of these signals (d 160 ppm, m1/2 = 3000 Hz) This
implies a rapid exchange of the Ph3Sn-fragment between
the two phosphorus nuclei on the NMR time scale
implying the existence of a dynamic process in solution.
Variable temperature 31P{1H} NMR spectroscopic anal-
ysis revealed a resolution of these signals at 213 K into
the expected [AX] pattern (d 315.1 and d 24.4 ppm
1
2J(PaPb) 13.4 Hz; with tin satellites J(PaSn) 686.5 Hz)
3J(PbSn) 115.4 Hz; in full agreement with the solid state
molecular structure.
The observation of two pseudo-triplets in the satel-
lite sub-spectrum of the Pa resonance may be
explained through virtual equivalence of the magni-
tudes of 117Sn and 119Sn phosphorus coupling.
Although these two Sn spin 1/2 isotopes have different
magnetogyric ratios, in practice the resulting differ-
ences in coupling to spin active hetero-nucleides is
small (<5%) and averaging of the satellites is often ob-
1
served. Discussions of J(PSn) couplings usually there-
1
fore employ the averaged 117Sn/119Sn value of J(SnP).
Similarly, no resolution of the 117Sn/119Sn coupling is
observed on the low field Pb resonance and the satel-
lite sub-spectra are observed as shoulders on the main
1
signal. The magnitude of J(PSn) is somewhat higher
than values reported for the corresponding 1-trimeth-
ylstannylphosphole derivatives such as Me3SnPC4R4
(532–577 Hz), which are stereochemically rigid in solu-
tion and this may reflect a larger s-character in the
P–Sn r-bond of (1a).
Fig. 6. Variable temperature 119Sn{1H} NMR spectra of (1a) (in
d8-toluene).

F. Geoffrey et al. / Journal of Organometallic Chemistry 690 (2005) 3983–3989
3987
Table 2
B3LYP/LANL2DZ( ) relative energies (in kcal/mol) of isomers 1–3
But
But
P
P
But
But
*
and their connecting transition structures, with different substituent
patterns
Pa
Pa
Pb
Pb
Ph3Sn
SnPh3
R: Me; R0:
Me (c)
R: Me; R0:
t-Bu (b)
R: Ph; R0:
t-Bu (a)
Fig. 7. sigmatropic shift in Ph3SnP3C2But2.
DE
0.0
DG
DE
0.0
DG
DE
DG
0.0
[A2X] signal bearing an averaged 1/2 (1J + 3J) PSn scalar
coupling constant. The NMR spectra thus provide
strong evidence for a migration of the Ph3Sn fragment
between the two phosphorus nuclei. The coupling con-
1
0.0
7.6
0.0
8.0
0.0
7.5
2
5.8
10.5
9.2
7.5
13.3
7.6
8.8
16.2
10.8
20.8
28.8
3
12.9
11.7
14.8
19.4
14.6
8.9
13.9
9.0
TS12
TS23
TS33
11.9
16.3
14.0
20.2
14.2
21.7
19.1
26.5
1
3
stants J(SnPa) and J(SnPb) were found to be opposite
1
in sign and it is likely that J(SnPa) is positive by anal-
ogy with data found for 1-stannylphospholes.
1
Analysis of the variable temperature H NMR data
First we compare the stability of 1 with respect to the
possible isomeric structures 2 and 3. The relative ener-
gies are collected in Table 2 and it is clear that the most
stable isomer structure is 1 for each substituent pattern
considered. Furthermore, the relative energies of the dif-
ferent structures show little dependence on the nature of
the substituents R and R0, indicating that the steric ef-
fects must play a minor role.
All the transition structures connecting the minima
are below 20 kcal/mol and the low barriers are, as ex-
pected, in accordance with the easy shift of the stannyl
groups in substituted cyclopentadienes [21]. Especially
noteworthy is the calculated barrier for the [1,2] H
migration, being in very good agreement with the bar-
rier concluded from the NMR investigations (see
above). Thus, while 1 is the most stable structure, iso-
mers 2 and 3 are also slightly populated and therefore,
if 2 (or 3) were to react with a substrate much faster than
1, it would be possible to obtain products derivable from
2 (or 3) since they can readily interconvert as shown in
Fig. 8.
of (1a), afforded a DGà value of 11.3 kcal/molꢀ for this
dynamic process, which is 3.9 kcal/molꢀ1 higher than
the value reported by Zenneck et al. for the [1,2] migra-
tion process in Ph3SnP3C2But2 (see Fig. 7 below).
4. Theoretical studies concerning the mechanism of the
migration process in Ph3SnP2C3But3 (1a)
The effect of the tin substitution on the 1,3-diphosp-
hole ring has been investigated by theoretical methods
t
on three sets of model compounds containing Me, Bu,
trimethylstannyl or triphenylstannyl substituents, as
shown in Scheme 1. Two further isomeric structures 2
and 3 were also considered, since it can be assumed that
they can be formed by an easy stannyl shift.
Recently Mathey [20] has drawn attention to the fact
that the rather reactive 2H-phospholes can, in many
cases, determine the reactivity of the corresponding
1H-phospholes, as a result of the easy interconversion
of the two systems, by a facile H-shift. Thus, it can be
expected that the reactivity of 1 will in fact be strongly
influenced by the reactivity of its isomers.
To understand the effects governing the relative sta-
bilities of the isomers 1, 2 and 3 it is necessary not only
to consider the aromatic stabilisation in each, but also
R'
R'
R'
R'
R'
R'
P
R3E
R'
P
P
ER3
P
P
P
R'
R'
R3E
2a R: Ph R': tBu E: Sn
2b R: Me R': tBu E: Sn
2c R: Me R': Me E: Sn
2d R: H R': Me E: Sn
2e R: - R': H E: H
1a R: Ph R': tBu E: Sn
1b R: Me R': tBu E: Sn
1c R: Me R': Me E: Sn
1d R: H R': Me E: Sn
1e R: - R': H E: H
3a R: Ph R': tBu E: Sn
3b R: Me R': tBu E: Sn
3c R: Me R': Me E: Sn
3d R: H R': Me E: Sn
3e R: - R': H E: H
Scheme 1.

3988
F. Geoffrey et al. / Journal of Organometallic Chemistry 690 (2005) 3983–3989
R'
SnR3
P
P
R'
R'
[TS12]
[TS12]
2
R'
R'
R3Sn
SnR3
P
P
P
P
R'
R'
R'
R'
1
1
[TS13]
[TS13]
R'
R'
[TS33]
P
P
P
P
R3Sn
SnR3
R'
R'
R'
R'
3
3
Fig. 8. Interconversion between 1, 2 and 3 via stannyl shifts.
the importance of the strengths of the bonds between the
different atoms. In isomer 1 for example there is a P–Sn
bond, while in isomers 2 or 3 a C–Sn bond exists with an
obviously different energy content.
5. Theoretical calculations
The density functional calculations were carried out
at the B3LYP/LANL2DZ( ) level [22], by using the
*
GAUSSIAN 98 suite of programs [23] At the optimised
structures second derivatives were calculated. For the
minima all second derivatives were positive (no imagi-
nary frequencies), and for the transition structures a sin-
gle negative eigenvalue of the Hessian was obtained. By
following the negative eigenvector a subsequent optimi-
sation resulted in those minima, which are connected by
the transition structure.
H
Me
Me
Me
H
Me
SnMe3
Me3Sn
Me
P
P
P
Me
SnMe3
H
H
H
H
4
5
6
In order to compare these two bonding situations, the
structures of the isomeric compounds 4 and 5 were also
calculated and the energy difference between these two
structures was found to be 5.8 kcal/mol. This is of simi-
lar magnitude to the energy difference determined for 1c
and 3c (6.2 kcal/mol). Likewise, although both 2 and 3
exhibit one SnCring bond, the position of the tetracoor-
dinate carbon is different, since in 2 it is connected to
two doubly bonded phosphorus atoms, while in 3 it is
connected to only one doubly bonded phosphorus.
Compound 6 is more stable by 2.1 kcal/mol than 5,
showing the preference of the tetracoordinate carbon
C(Sn) to be situated at an adjacent phosphorus atom.
Similarly, 2 is more stable than 3 by 3.9 kcal/mol. and
thus the relative energies of the isomers are mainly re-
lated to the strengths of the bonds between the different
atoms and the small interactions between the neighbour-
ing moieties, while aromaticity has a little effect on the
relative energies.
6. Experimental section and computation
All manipulations were carried out using conven-
tional high vacuum and Schlenk line techniques, under
an atmosphere of dry argon, or under a dinitrogen
atmosphere in an MBraun or Miller–Howe glove box.
Solvents were refluxed over suitable drying agents, and
distilled and degassed prior to use. Toluene and benzene
were refluxed over sodium. Heptane and THF were re-
fluxed over potassium. Petroleum ether (40–60 ꢁC) and
pentane were refluxed over sodium/potassium alloy.
NMR solvents were dried over potassium (d6-benzene),
sodium (d8-toluene) or calcium hydride (d2-dichloro-
methane), then vacuum transferred into ampoules and
stored under dinitrogen prior to use. NMR spectra were
recorded on a Bruker DPX 300 or a Bruker AMX 500
spectrometer, Chemical shifts in ppm (d) are relative

F. Geoffrey et al. / Journal of Organometallic Chemistry 690 (2005) 3983–3989
3989
to the residual proton chemical shift of the deuterated
solvent (1H), the carbon chemical shift of the deuterated
solvent (13C) and H3PO4 (31P) and Me4Sn (119Sn). Mass
spectra were recorded on a VG autospec Fisons instru-
ment (Electron ionisation at 70 eV) by Dr. A. Abdul-
Sada. Elemental analysis was performed by Micro
Analytisches Labor Pascher (Germany).
support of this research. Generous allocation of com-
puter time from the NIIF Supercomputer Centre (Buda-
pest) is also gratefully acknowledged. J.F.N. and L.N.
acknowledge joint support from the Royal Society.
References
[1] F.G.N. Cloke, P.B. Hitchcock, J.F. Nixon, D.J. Wilson, Organo-
metallics 19 (2000) 219.
7. Synthesis of Ph3SnP2C3But3 (1a)
[2] F.G.N. Cloke, J.C. Green, P.B. Hitchcock, J.F. Nixon, J. Suter,
D.J. Wilson, in preparation.
A Schlenk tube was charged with KðTHFÞP2C3Bu3t
(0.200 g, 0.526 mmol), Ph3SnCl (0.202 g, 0.526 mmol)
and THF (30 ml) and the reaction mixture was stirred
for 12 h. The resulting yellow suspension was filtered
through diatomaceous earth, the solvent removed in va-
cuo from the filtrate and the yellow oily solid recrystal-
lised from cold hexanes yielding (1a) as a yellow powder
(yield 0.270 g, 82%).
[3] J.R.Hanks, unpublished results, Ph.D. Thesis University of
Sussex, 2000.
[4] S. Al-Juaid, P.B. Hitchcock, R.M. Matos, J.F. Nixon, J. Chem.
Soc., Chem. Commun. (1993) 267.
[5] P. Jutzi, M. Kuhn, J Organomet. Chem. 173 (1979) 221;
E.C. Lund, T. Livinghouse, Organometallics 9 (1990) 2426.
[6] F. Nief, F. Mathey, J. Chem. Soc. Chem. Commun. (1998) 770.
[7] J.J. Durkin, unpublished results, Ph.D. Thesis, University of
Sussex, 1995.
1H NMR data (d6-benzene, 295 K): d 7.60–7.06 (m,
15 H, Sn(C6H5)3), 1.47 (s, br, 18H, CC(CH3)3), 1.18 (s,
9H, PCC(CH3)3P).
[8] F.W. Heinemann, H. Pritzkow, M. Zeller, U. Zenneck, Organo-
metallics 20 (2001) 2905.
[9] M. Hofmann, F.W. Heinemann, U. Zenneck, J. Organometal.
Chem. 643 (2002) 357.
13C{1H} NMR data (d8-toluene, 295 K): d 202.1 (t,
[10] F.W. Heinemann, H. Pritzkow, M. Zeller, U. Zenneck, Organo-
metallics 19 (2000) 4283.
2
PCP, J(PC) 47.3, J(SnC) 31.16 Hz), 141.8 (p-C6H5,
4J(SnC) 4 Hz), 135.0 (ipso-C6H5, J(SnC) 35.6 Hz), 126.7
[11] A. Elvers, F.W. Heinemann, B. Wrackmeyer, U. Zenneck,
Chemistry A: Eur. J. 5 (1999) 3143.
2
(o-C6H5, J(SnC) 6.2 Hz) 37.0 (t, PCC(CH3)3P, J(PC)
2
[12] A. Elvers, F.W. Heinemann, M. Heinemann, M. Zeller, U.
Zenneck, Angew. Chem. Int. Edn. Engl. 39 (2000) 2087.
[13] A. Elvers, F.W. Heinemann, S. Kummer, B. Wrackmeyer, M.
Zeller, U. Zenneck, Phosphorus Sulfur Silicon and Rel. Elements
146 (1999) 725.
2
15.73 Hz), 36.4 (d, CC(CH3)3C, J(PC) 24.28 Hz), 32.7
(PCC(CH3)3P), 32.5 (br, CC(CH3)3).
31P{1H} NMR data (d8-toluene, 215 K): d 315.1 (d,
CPbC, J(PP) 13.39 Hz, J(PSn) 115.4 Hz), 24.4 (d,
2
3
[14] F.G.N. Cloke, P.B. Hitchcock, P. Hunnable, J.F. Nixon, L.
Nyulaszi, E. Neicke, V. Thelen, Angew. Chem. Angew. Chem.,
Int. Ed. Engl. 37 (1998) 1083.
2
PaSnPh3, J(PP) 13.39 Hz, J(PSn) 686.52 Hz).
119Sn{1H} NMR data (d8-toluene, 223 K): d ꢀ146.2
3
(dd, J(SnP) 700.7, J(SnP) 124.6 Hz).
[15] V. Caliman, P.B. Hitchcock, J.F. Nixon, J. Chem. Soc. Chem.
Commun. (1995) 1661.
119Sn{1H} NMR data (d8-toluene, 333 K): d ꢀ145 (t,
2J(SnP) 288 Hz).
´
[16] L. Nyulaszi, J. Phys. Chem. 100 (1996) 6194.
[17] A. Dransfeld, L. Nyula´szi, P.v R. Schleyer, Inorg. Chem. 37
(1998) 4413.
EI-MS m/z (%): 620(55) [M]+, 543 (8) [M ꢀ Ph]+,
482(25) [M(ButCCBut)]+, 351(100) ½M ꢀ P2C3But ꢁ.
3
[18] L. Nyula´szi, P.v R. Schleyer, J. Am. Chem. Soc. 121 (1999) 6872.
[19] In Fig 4, the Kohn–Sham orbitals are shown and are essentially
the same as the canonical HF MOs.
7.1. Crystal data for (1a)
[20] F. Mathey, Acc. Chem. Res. 37 (2004) 954.
[21] Yu.A. Ustynyuk, A.V. Kisin, A.A. Zenkin, J. Organomet. Chem.
37 (1972) 101;
C33H42P2Sn, M = 619.30, orthorhombic, space group
˚
P212121, a = 8.840(2) A, b = 17.120(5) A, c = 20.418(6)
˚
Yu.K. Grishin, N.M. Sergeyev, Yu.A. Ustynyuk, J. Organomet.
Chem. 22 (1970) 361.
3
A, V = 3090.2(2) A , T = 173(2) K, Z = 4, Dc = 1.33
˚
˚
Mg mꢀ3, l = 0.95 mmꢀ1, k = 0.71073 A, F(000) = 1280,
[22] d polarization fuctions with exponents 0.183, 0.55 and 0.8 were
added to Sn, P and C atoms, respectively.
˚
crystal size 0.40 · 0.40 · 0.40 mm3, 17939 measured
reflections, 9001 independent reflections (Rint = 0.0477),
8138 reflections with I > 2r(I), Final indices R1 = 0.032,
wR2 = 0.062 for I > 2r(I), R1 = 0.041, wR2 = 0.079 for
all data. Data collection: Enraf Nonius CAD4. Struc-
ture solution Program package WINGX. Refinement
using SHELXL-97.
[23] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A.
Robb, J.R. Cheeseman, V.G. Zakrzewski, J.A. Montgomery Jr.,
R.E. Stratmann, J.C. Burant, S. Dapprich, J.M. Millam, A.D.
Daniels, K.N. Kudin, M.C. Strain, O. Farkas, J. Tomasi, V.
Barone, M. Cossi, R. Cammi, B. Mennucci, C. Pomelli, C.
Adamo, S. Clifford, J. Ochterski, G.A. Petersson, P.Y. Ayala, Q.
Cui, K. Morokuma, D.K. Malick, A.D. Rabuck, K. Raghava-
chari, J.B. Foresman, J. Cioslowski, J.V. Ortiz, B.B. Stefanov, G.
Liu, A. Liashenko, P. Piskorz, I. Komaromi, R. Gomperts, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A.
Nanayakkara, C. Gonzalez, M. Challacombe, P.M.W. Gill, B.
Johnson, W. Chen, M.W. Wong, J.L. Andres, C. Gonzalez, M.
Head-Gordon, E.S. Replogle, J.A. Pople, GAUSSIAN 98, Revision
A.5, Gaussian Inc., Pittsburgh, PA, 1998.
Acknowledgements
The authors are grateful to the Hungarian Research
Fund (OTKA Grants T 034675 and D42216) for grant