The synthesis and structural characterisation of the first phosphavinyl-Group 13 complexes

Article abstract of DOI:10.1016/S0022-328X(01)00840-3

The bisphosphavinyl indium complex, [CyIn{C(^tBu)=PCy}₂], has been prepared from the reaction of two equivalents of [CyP=C(^tBu)MgCl(OEt₂)] with CyInBr₂. Its crystal structure shows it to be monomeric with a trigonal planar indium centre. The reactions of [CyP=C(^tBu)MgCl(OEt₂)] with MX₃, M=Al, Ga or In, X=Cl or Br, leads to facile phosphavinyl coupling reactions and the formation of the diphosphametallobicyclo[1.1.1]pentane complexes, [M{C₂(^tBu)₂P₂Cy₂}{C( ^tBu)=PCy}], which contain terminal phosphavinyl ligands.

Full text of DOI:10.1016/S0022-328X(01)00840-3

Journal of Organometallic Chemistry 629 (2001) 109–113
www.elsevier.com/locate/jorganchem
The synthesis and structural characterisation of the first
phosphavinyl–Group 13 complexes
Cameron Jones *, Anne F. Richards
Department of Chemistry, Uni6ersity of Wales, Cardiff, P.O. Box 912, Park Place, Cardiff, CF1O 3TB, UK
Received 28 February 2001; accepted 29 March 2001
Abstract
The bisphosphavinyl indium complex, [CyIn{C(tBu)ꢀPCy}2], has been prepared from the reaction of two equivalents of
[CyPꢀC(tBu)MgCl(OEt2)] with CyInBr2. Its crystal structure shows it to be monomeric with a trigonal planar indium centre. The
reactions of [CyPꢀC(tBu)MgCl(OEt2)] with MX3, M=Al, Ga or In, X=Cl or Br, leads to facile phosphavinyl coupling reactions
and the formation of the diphosphametallobicyclo[1.1.1]pentane complexes, [M{C2(tBu)2P2Cy2}{C(tBu)ꢀPCy}], which contain
terminal phosphavinyl ligands. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Phosphavinyl; Low coordination; Group 13; Group 15; Cage; Phosphorus; Heterocycle; Crystal structure
1. Introduction
which we have used as a transfer reagent in the prepa-
ration of the first bis-phosphavinyl tin complex,
[SnMe2{C(tBu)ꢀPCy}2] [3]. As a result of this work it
seemed likely that metathesis reactions of 1 with Group
13 halide compounds would lead to hetero- and ho-
moleptic phosphavinyl–group 13 complexes. The re-
sults of our efforts in this area are reported herein.
Vinyl–Group 13 complexes, especially those of alu-
minium, have found a variety of applications in
organometallic synthesis and have been utilised in a
wide range of organic transformations [1]. We have
recently embarked upon an investigation into the syn-
thesis and reactivity of main group phosphavinyl com-
plexes, [M{C(R)ꢀPR}n], M=main group element
[2–4], which we hoped would include Group 13–phos-
phavinyl complexes as we believed these might find a
similar range of applications as their vinyl counterparts.
In this context, it is noteworthy that we have previously
reported a general, high yielding synthetic route to a
range of phosphavinyl Grignard reagents, e.g.
[CyPꢀC(tBu)MgCl(OEt2)] (1), Cy=cyclohexyl [2],
2. Results and discussion
In an attempt to prepare a heteroleptic phosphavinyl
indium complex, two equivalents of 1 were reacted with
in situ generated CyInBr2 in toluene to yield the first
example of a Group 13–phosphavinyl complex, 2, in
moderate yield (40%) after recrystallisation from tolu-
ene (Scheme 1). The compound is thermally stable and
displays a low field singlet (l 329 ppm) in its 31P{1H}-
NMR spectrum which is in the region normally associ-
ated with metallophosphaalkenes [5]. This suggested
that compound 2 had been formed as its Z,Z-isomer
though the possibility of it existing in its E,E-form
could not be ruled out.
Scheme 1.
In order to confirm its stereochemistry an X-ray
crystal structure analysis was carried out. Its molecular
structure (Fig. 1, Table 1) showed it to exist as its
Z,Z-isomer. In addition the compound was found to be
* Corresponding author. Tel: +44-29-20874060; fax: +44-29-
20874030.
E-mail address: jonesca6@cardiff.ac.uk (C. Jones).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00840-3

110
C. Jones, A.F. Richards / Journal of Organometallic Chemistry 629 (2001) 109–113
cyclohexyl group of 2 relative to the chloride ligand of
4 prevents this in some way. Of course the reaction
could proceed via an intermediate trisphosphavinyl
complex, [M{C(tBu)ꢀPCy}3] prior to coupling, but our
isolation of the phosphorus counterpart of 5, i.e. M=P
[6], from the analogous reaction of PCl3 with three
equivalents of 1 would suggest this is not the case. It is
Table 1
Summary of crystallographic data for complexes 2, 3a and 3b
2
3a
3b
Empirical
formula
Mr
Temperature
(K)
C28H51InP2
C33H60AlP3
C
33H60GaP3
564.45
150(2)
576.70
150(2)
619.44
150(2)
Wavelength
0.71073
0.71073
0.71073
,
(A)
Crystal system Triclinic
Monoclinic
Monoclinic
(
Space group
Unit cell dimensions
P1
P2(1)/n
P2(1)/n
,
a (A)
9.948(4)
11.435(4)
13.566(5)
94.96(3)
101.27(3)
96.16(4)
1495.5(10)
2
10.514(2)
30.924(6)
11.490(2)
90
115.40(3)
90
10.597(8)
31.032(6)
11.480(7)
90
115.58(6)
90
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
V (A )
,
Fig. 1. Molecular structure of 2. Selected bond lengths (A) and angles
(°): In(1)ꢁC(12), 2.175(4); In(1)ꢁC(23), 2.183(4); In(1)ꢁC(1), 2.191(4);
P(1)ꢁC(1), 1.664(4); P(1)ꢁC(6), 1.867(5); P(2)ꢁC(12), 1.677(4);
P(2)ꢁC(17), 1.865(4); C(1)ꢁC(2), 1.534(6); C(12)ꢁC(13), 1.515(5);
3
,
3374.7(11)
4
3405(3)
4
Z
C(12)ꢁIn(1)ꢁC(23),
C(23)ꢁIn(1)ꢁC(1),
C(12)ꢁP(2)ꢁC(17),
115.84(15);
122.50(15);
105.66(19);
C(12)ꢁIn(1)ꢁC(1),
C(1)ꢁP(1)ꢁC(6),
P(1)ꢁC(1)ꢁIn(1),
121.57(15);
105.4(2);
122.7(2);
Crystal size
(mm)
0.3×0.2×0.2
0.3×0.4×0.2
0.2×0.2×0.15
Colour
Colourless
0.910
596
Yellow
0.222
1264
Yellow
0.969
1336
P(2)ꢁC(12)ꢁIn(1), 121.5(2).
v (mm−1
F(000)
)
monomeric with a trigonal planar indium centre (ꢀ
angles about In(1) 359.9°). The geometry of both phos-
phavinyl fragments is similar and both the P(1)ꢁC(1)
and P(2)ꢁC(12) bond lengths are in the normal region
for localised PꢁC double bonds [5]. All other bond
lengths and angles within the compound are in the
normal ranges.
Reflections
collected
Rint
5604
6396
6407
0.0138
5359
0.0301
6054
0.1468
6094
Unique
reflections
Parameters
varied
R [I\2|(I)]
Rw (all data)
286
343
343
0.0454
0.0502
0.0500
0.1375
0.0653
0.2657
We also attempted the preparation of a series of
homoleptic trisphosphavinyl–Group 13 complexes by
the reaction of three equivalents of 1 with the appropri-
ate Group 13 halide (Scheme 2). Unexpectedly, how-
ever, the reactions led to the formation of the novel
diphosphametallobicyclo[1.1.1]pentane complexes, 3a–
3c, in low to moderate yields. We cannot be sure of the
mechanism of formation of these compounds as the
reactions proceeded too rapidly to observe any interme-
diates by 31P-NMR spectroscopy. However, it is be-
lieved that the metal halide initially reacts with two
equivalents of 1 to give the intermediate, 4, which is
structurally similar to 2. This then undergoes a facile
intramolecular phosphavinyl coupling reaction to give 5
which reacts with a third equivalent of 1 to give 3. If
this is the case, it is not known why 2 does not undergo
a similar coupling to 4 but perhaps the bulk of the
Scheme 2.

C. Jones, A.F. Richards / Journal of Organometallic Chemistry 629 (2001) 109–113
111
,
Fig. 2. Molecular structure of 3a. Selected bond lengths (A) and angles (°): P(1)ꢁC(1), 1.676(3); P(1)ꢁC(6), 1.864(3); Al(1)ꢁC(1), 1.960(3);
Al(1)ꢁC(12), 1.983(3); Al(1)ꢁC(13), 1.958(3); P(2)ꢁC(12), 1.896(3); P(2)ꢁC(13), 1.912(3); P(3)ꢁC(12), 1.895(3); P(3)ꢁC(13), 1.915(3); C(6)ꢁP(1)ꢁC(1),
106.10(14); P(1)ꢁC(1)ꢁAl(1), 112.78(15); C(13)ꢁAl(1)ꢁC(12), 74.24(11); C(12)ꢁP(3)ꢁC(13), 77.27(12); C(12)ꢁP(2)ꢁC(13), 77.31(12); P(3)ꢁC(12)ꢁP(2),
86.58(12); P(3)ꢁC(12)ꢁAl(1), 85.25(11); P(2)ꢁC(12)ꢁAl(1), 86.05(11); P(2)ꢁC(13)ꢁP(3), 85.56(11); P(2)ꢁC(13)ꢁAl(1), 86.32; P(3)ꢁC(13)ꢁAl(1),
85.40(11).
worth noting that the formations of 3a–3c are notion-
ally related to the reactions of aluminium and gallium
trialkyls with phosphaalkynes, PꢂCR, which also do
not lead to Group 13–trisphosphavinyl complexes via
1,2-additions, but instead to triphosphametallatobicy-
clo[3.2.0.02,6]heptenes, again via coupling reactions [7].
The spectroscopic data for 3a–3c are similar and the
31P{1H}-NMR spectrum of each displays a three signal
pattern with a low field singlet in the expected region
for metallophosphaalkenes [5]. Singlets for the chemi-
cally inequivalent saturated phosphorus centres were
observed at higher field, though no two bond PꢁP
couplings between the signals were evident. The reason
for this apparently lies with the acute CPC angles, and
thus a high degree of p-character to the bonds within
the cage framework. All other spectroscopic data for
3a–3c are consistent with the proposed structures.
The X-ray crystal structures of 3a and 3b were ob-
tained and found to be isomorphous (Figs. 2 and 3, see
Table 1). The compounds are monomeric with trigonal
planar metal coordination environments (ꢀ angles
lengths of the terminal phosphavinyl fragments in both
the aluminium and gallium compounds are close to
each other and consistent with localised PꢁC double
bonds [5].
One of our current research goals is the linear poly-
merisation of phosphaalkynes. We are interested in this
area as polyphosphaalkynes could be considered as
analogues of polyacetylenes which have found a num-
ber of applications derived from their interesting elec-
tronic properties [9]. As compounds 3a–3c have
unsaturated three coordinate metal centres it seemed
possible that their reaction with an excess of the phos-
phaalkyne, PꢂCtBu, might lead to initial coordination
at the metal centre followed by sequential insertion of
the PꢂC bond into the terminal MꢁC bond of the cage
to give an unsaturated organophosphorus polymer
chain. To investigate this possibility 3a was reacted
with PꢂCtBu in a number of stoichiometries, however
in all cases complex mixtures of soluble phosphorus
containing products were obtained and therefore our
efforts in this area have been abandoned.
about
M−359.9°)
and
metallodiphosphabicy-
clo[1.1.1]pentane cage frameworks. The CPC and CMC
angles within the cages are acute (ca. 70–80°) and can
be compared to the CPC angles [74.1(3)°] in the struc-
turally similar triphosphabicyclo[1.1.1]pentane com-
pound, tBuC{P(Cl)}3CtBu [8]. The P(1)ꢁC(1) bond
3. Conclusions
We have prepared a number of novel compounds
from the reactions of phosphavinyl Grignard reagents

112
C. Jones, A.F. Richards / Journal of Organometallic Chemistry 629 (2001) 109–113
with Group 13–halide complexes. These include the
first examples of terminal phosphavinyl–Group 13
complexes, 2 and 3, several examples of which, 3a–3c,
are formed via a facile phosphavinyl coupling reaction.
We are currently extending this study to explore the
interaction of 1 with other main group halides, initial
results of which are showing remarkable differences
between the chemistries of phosphavinyl and vinyl
Grignard reagents. The outcome of these explorations
will be the subject of a forthcoming publication.
out at the Warwick Analytical Service. Reproducible
elemental analyses of 3a–c could not be obtained due
to the air sensitivity of these compounds. 13C data for 2
were difficult to obtain due to its low solubility in
non-coordinating solvents. 13C data for 3a–c were
difficult to interpret due to numerous overlapping
peaks and phosphorus couplings. Compound 1 was
prepared by a literature procedure [2]. All other
reagents were used as received.
4.1. CyIn{C(tBu)ꢀPCy}2 (2)
To a suspension of InBr3 (0.20 g) in toluene (20 ml)
at −78°C was added CyMgCl (0.28 ml of 2 M Et2O
solution, 0.56 mmol). The resulting suspension was
warmed to room temperature (r.t.) and stirred
overnight. The solution was cooled to −78°C and to
this was added a solution of 1 (0.35 g, 1.12 mmol) in
toluene (10 ml). The resulting solution was warmed to
r.t. and stirred for 6 h whereupon it was filtered and
cooled to −30°C to yield colourless crystals of 2 (0.13
g, 40%), m.p. 74–76°C. 1H-NMR (400 MHz, C6D6, 298
K): l 1.29 (s, 18H, tBu), 1.0–1.9 (m, 33H, Cy).
31P{1H}-NMR (145.8 MHz, C6D6): l 329 (PꢀC). IR
(Nujol, w cm−1): 1023 (m), 802 (m) 727 (m), MS APCI;
m/z: 482 ([M+−Cy], 15), 367 ([CyPCtBuInCtBu+],
100), 298 ([CyPCtBuIn+], 15%); Anal. Found: C, 58.99;
H, 9.00. Calc. for C28H51InP2: C, 59.90; H, 8.62%.
4. Experimental
All manipulations were carried out using standard
Schlenk and glove box techniques under an atmosphere
of high purity Ar or dinitrogen. Toluene was distilled
over potassium then freeze–thaw degassed prior to use.
1H- and 31P-NMR spectra were recorded on either a
Bruker AMX360 or Bruker DPX400 spectrometer in
1
C6D6 and were referenced to the residual H resonances
of the solvent used (1H-NMR) or to external 85%
H3PO4, 0.0 ppm (31P-NMR). Mass spectra were
recorded using a VG Fisons Platform II instrument
under APCI conditions. Melting points were deter-
mined in sealed glass capillaries under Ar, and are
uncorrected. The elemental analysis of 2 was carried
,
Fig. 3. Molecular structure of 3b. Selected bond lengths (A) and angles (°): P(1)ꢁC(1), 1.683(7); P(1)ꢁC(6), 1.879(8); Ga(1)ꢁC(1), 1.968(7);
Ga(1)ꢁC(12), 2.023(8); Ga(1)ꢁC(13), 2.005(7); P(2)ꢁC(12), 1.892(7); P(2)ꢁC(13), 1.957(8); P(3)ꢁC(12), 1.882(8); P(3)ꢁC(13), 1.947(8);
C(1)ꢁP(1)ꢁC(6), 106.2(3); Ga(1)ꢁC(1)ꢁP(1), 115.7(4); C(13)ꢁGa(1)ꢁC(12), 73.5(3); C(12)ꢁP(2)ꢁC(13), 77.5(3); C(12)ꢁP(3)ꢁC(13), 78.0(3);
P(3)ꢁC(12)ꢁP(2), 87.4(3); P(3)ꢁC(12)ꢁGa(1), 87.2(3); P(2)ꢁC(12)ꢁGa(1), 85.7(3); P(3)ꢁC(13)ꢁP(2), 83.9(3); P(3)ꢁC(13)ꢁGa(1), 86.0(3);
P(2)ꢁC(13)ꢁGa(1), 84.5(3).

C. Jones, A.F. Richards / Journal of Organometallic Chemistry 629 (2001) 109–113
113
t
4.2. Al(C2 Bu2P2Cy2){C(tBu)ꢀPCy} (3a)
refined on F2 by full-matrix least-squares (SHELX-97)
[10] using all unique data. All non-hydrogen atoms are
anisotropic with H-atoms included in calculated posi-
tions (riding model). Empirical absorption corrections
were carried out by the DIFABS method [11]. The data
for the structure of compound 3b were weak but the
fact that this structure is isomorphous to that of 3a
leaves no doubt about the gross molecular framework
of the compound.
To a suspension of AlCl3 (0.05g, 0.37 mmol) in
toluene (25 ml) at −78°C was added a solution of 1
(0.35 g, 1.11 mmol) in toluene (10 ml). The resulting
suspension was warmed to r.t., stirred overnight and
filtered. The filtrate was reduced and placed at −30°C
to yield yellow crystals of 3a (0.10 g, 49%), m.p. (dec.)
175−180°C. 1H-NMR (400 MHz, C6D6, 298 K): l
0.95 (br. s, 18H, Bu), 1.40 (s, 9H, Bu), 0.92–2.21 (m,
33H, Cy). 31P{1H}-NMR (145.8 MHz, C6D6): l 23.6 (s,
PCy), 37.9 (s, PCy), 353 (PꢀC). IR (Nujol, w cm−1):
1376 (m), 1260 (m) 1020 (m). MS APCI; m/z: 367
([P2Cy2Ct2Bu2], 100), 284 ([P2CyC2t Bu2], 15%).
t
t
6. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 158733, 158734 and 158735
for compounds 2, 3a and 3b, respectively. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (Fax: +44-1223-336033; e-mail: deposit@
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
t
4.3. Ga(C2 Bu2P2Cy2){C(tBu)ꢀPCy} (3b)
To a suspension of GaCl3 (0.06 g, 0.34 mmol) in
toluene (25 ml) at −78°C was added a solution of 1
(0.35 g, 1.11 mmol) in toluene (10 ml). The resulting
suspension was warmed to r.t., stirred overnight and
filtered. The filtrate was reduced and placed at −30°C
to yield yellow crystals of 3b (0.03 g, 15%), m.p. (dec.)
1
115–118°C. H-NMR (400 MHz, C6D6, 298 K): l 1.24
t
t
Acknowledgements
(br. s, 18H, Bu), 1.75 (s, 9H, Bu), 1.08–2.32 (m, 33H,
Cy). 31P{1H}-NMR (145.8 MHz, C6D6): l 4.1 (s, PCy),
29.0 (s, PCy), 333 (PꢀC). IR (Nujol, w cm−1): 1376 (m),
1260 (m) 1092 (m), 800 (m). MS APCI; m/z: 454
[M+−2Cy].
We gratefully acknowledge support from the EPSRC
(studentship for A.F.R.).
t
4.4. In(C2 Bu2P2Cy2){C(tBu)ꢀPCy} (3c)
References
[1] E.W. Abel, F.G.A. Stone, G. Wilkinson (Eds.), Comprehensive
Organometallic Chemistry II, vol. 11, Pergamon, New York,
1995.
[2] D.E. Hibbs, C. Jones, A.F. Richards, J. Chem. Soc. Dalton
Trans. (1999) 3531.
[3] C. Jones, A.F. Richards, J. Chem. Soc. Dalton Trans. (2000)
3233.
[4] C. Jones, J.A. Platts, A.F. Richards, Chem. Commun., 2001,
663.
[5] (a) L. Weber, Angew. Chem. Int. Ed. Engl. 35 (1996) 271;
(b) K.B. Dillon, F. Mathey, J.F. Nixon, Phosphorus: The Car-
bon Copy, Wiley, Chichester, 1998 (and references therein).
[6] C. Jones, A.F. Richards, unpublished results.
[7] A. Hoffmann, A. Mack, R. Goddard, P. Binger, M. Regitz, Eur.
J. Inorg. Chem. (1998) 1597.
To a suspension of InBr3 (0.24 g, 0.68 mmol) in
toluene (25 ml) at −78°C was added a solution of 1
(0.70 g, 2.2 mmol) in toluene (10 ml). The resulting
suspension was warmed to r.t., stirred overnight and
filtered. The filtrate was reduced and placed at −30°C
to yield yellow crystals of 3c (0.19 g, 42%), m.p. 74–
1
76°C. H-NMR (400 MHz, C6D6, 298 K): l 1.40 (br. s,
t
t
18H, Bu), 1.72 (s, 9H, Bu), 1.09–2.41 (m, 33H, Cy).
31P{1H}-NMR (145.8 MHz, C6D6): l 8.8 (s, PCy), 24.2
(s, PCy), 329 (PꢀC). IR (Nujol, w cm−1): 1377 (m), 1262
(m) 1018 (m). MS APCI; m/z: 367 ([P2Cy2Ct2Bu2], 100),
298 ([CyPCtBuIn], 20%).
[8] P. Binger, T. Wenling, R. Schneider, F. Zurmu¨hlen, U.
Bergstra¨sser, J. Hoffmann, G. Maas, M. Regitz, Angew. Chem.
Int. Ed. Engl. 30 (1991) 207.
[9] T. Masuda, T. Higashimura, Acc. Chem. Res. 17 (1984) 51 (and
references therein).
[10] G.M. Sheldrick, SHELX-97, University of Go¨ttingen, 1997.
[11] Z. Otwinowski, W. Minor, in: C.W. Carter, R.M. Sweet (Eds.),
Methods in Enzymology, Academic Press, New York, 1996.
5. Crystallographic studies
All crystallographic measurements were made using
an Enraf–Nonius CAD4 diffractometer. The structures
of 2, 3a and 3b were solved by direct methods and
.