Organo-functionalised arsine and stibine organometallics; syntheses and structural characterisations (see abstract)

Article abstract of DOI:10.1016/S0277-5387(02)01339-6

A series of dinuclear organo-functionalised stibine and arsine ligands incorporating a range of hard, soft and π-donor moieties have been synthesised from the reactions of Cl₂Sb(CH₂)₃SbCl₂ and Cl₂AsCH₂AsCl₂ with a range of organolithium reagents. The X-ray structures of 1,3-[(PhC≡C)₂Sb]₂(CH₂)₃ (1), As(C≡CPh)₃ (2), R₂AsCH₂AsR₂ [R = Me₃SiC≡C, 3; (Me₃Si)₂N, 4; and 2-SPy 5] have been determined. Compound 5 associates into pseudo dimers as a result of intermolecular π-π stacking between the pyridyl groups on one end of two separate diarsine molecules. Whereas the bridging unit remains intact during the syntheses of 1 and 3-5, the formation of the mononuclear trisacetylide species 2, involves the unexplained cleavage of the bridging methylene unit.

Full text of DOI:10.1016/S0277-5387(02)01339-6

Polyhedron 22 (2003) 211Á216
/
www.elsevier.com/locate/poly
Organo-functionalised arsine and stibine organometallics; syntheses
and structural characterisations of 1,3-[(PhCÅC)2Sb]2(CH2)3,
As(CÅCPh)3, R2AsCH2AsR2 [RꢀMe3SiCÅC-, (Me3Si)2N-
and 2-SPy] with p-stacking in the latter
/
/
/
/
Michael A. Paver a,ꢁ, Jonathan S. Joy a, Simon J. Coles a, Michael B. Hursthouse a,
J.E. Davies b
a Department of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK
b Department of Chemistry, Cambridge University, Cambridge CB2 1EW, UK
Received 29 August 2002; accepted 28 October 2002
Abstract
A series of dinuclear organo-functionalised stibine and arsine ligands incorporating a range of hard, soft and p-donor moieties
have been synthesised from the reactions of Cl2Sb(CH2)3SbCl2 and Cl2AsCH2AsCl2 with a range of organolithium reagents. The X-
ray structures of 1,3-[(PhCÅ
have been determined. Compound 5 associates into pseudo dimers as a result of intermolecular pÁ
groups on one end of two separate diarsine molecules. Whereas the bridging unit remains intact during the syntheses of 1 and 3Á
/
C)2Sb]2(CH2)3 (1), As(CÅ
/
CPh)3 (2), R2AsCH2AsR2 [Rꢀ
/
Me3SiCÅ
/
C, 3; (Me3Si)2N, 4; and 2-SPy 5]
p stacking between the pyridyl
5,
/
/
the formation of the mononuclear trisacetylide species 2, involves the unexplained cleavage of the bridging methylene unit.
# 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Stibine; Arsine; Synthesis; X-ray structures; p-Stacking; Group 15
1. Introduction
Me, Ph), have been used to generate a host of hetero-
metallic coordination complexes [9]. However, to date
there have been only limited examples of organo-
functionalised binuclear species [10]. It was thus our
intention to investigate the syntheses and reactivities of
a series of novel organo-substituted polynuclear Group
15 ligands containing side-arm donors possessing a more
diverse set of donor functionalities incorporating hard
(N) and soft (As, S) Lewis base sites as well as p-systems
The organometallic and ligand chemistry of Group 15
is now well established [1]. Previous work into the
reactivities of Group 15 dimethylamido derivatives,
E(NMe2)3 (EꢀAs, Sb, Bi) [2], has generated a range
/
of heteropolymetallic cage species, the structural diver-
sity of which is the subject of a great deal of interest
[3,4]. To further this work, we have investigated the
synthesis and characterisation of mixed-metal com-
pounds based around polynuclear Group 15 backbones
[5,6]. In the course of this work we have thus investi-
gated the possible functionalisation of polynuclear
Group 15 bimetallic precursors.
(CÅ
/
C and Py). By having multiple sites on the ligand
available for reaction it may be possible to tune
reactivity and create larger heterometallic species in-
corporating a number of different metal complexes.
Utilising dinuclear arsine and stibine frameworks we
have been able to synthesise a number of new organo-
metallic species. Here we report the syntheses of the
organofunctionalised stibine and arsine compounds 1,3-
Recently there has been great interest in the use of
binuclear Group 15 complexes as Lewis base donors
towards transition metal species [7,8]. The complexes
R2E(CH2)nER2 (where Eꢀ
/
P, As, Sb; nꢀ
/
1, 2, 3; Rꢀ
/
[(PhCÅ
AsR2 [Rꢀ
(Fig. 1).
/
C)2Sb]2(CH2)3 (1), As(CÅ
/
CPh)3 (2), R2AsCH2-
/
Me3SiCÅC, 3; (Me3Si)2N, 4; and 2-SPy 5]
/
ꢁ Corresponding author
E-mail address: m.a.paver@soton.ac.uk (M.A. Paver).
0277-5387/02/$ - see front matter # 2002 Elsevier Science Ltd. All rights reserved.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 1 3 3 9 - 6

212
M.A. Paver et al. / Polyhedron 22 (2003) 211Á216
/
˚
Fig. 1. Crystal structures of compounds 1Á
atoms are omitted for clarity: (a) molecular structure of 1. Sb(1)Ã
C(1)ÃSb(1)ÃC(3) 96.5(2), C(11)ÃSb(1)ÃC(3) 94.8(3), Sb(1)ÃC(3) 2.096(7), C(11)Ã
1.907(6), C(1)ÃC(2) 1.199(9), C(1)#1ÃAs(1)ÃC(1) 96.4(3); (c) molecular structure of 3. As(1)Ã
1.913(6), As(2)ÃC(1) 1.957(6), As(2)ÃC(21) 1.908(6), As(2)ÃC(16) 1.902(7), As(1)ÃC(1)ÃAs(2) 115.3(3), C(11)Ã
C(1) 96.2(3), C(6)ÃAs(1)ÃC(1) 96.9(3), C(16)ÃAs(2)ÃC(21) 97.5(3), C(21)ÃAs(2)ÃC(1) 96.0(3), C(16)ÃAs(2)ÃC(1) 96.4(3); (d) molecular structure of
4. As(1)ÃC(25) 1.972(7), As(1)ÃN(1) 1.893(6), As(1)ÃN(2) 1.898(6), As(2)ÃC(25) 1.981(7), As(2)ÃN(3) 1.893(6), As(2)ÃN(4) 1.901(6), As(1)ÃC(25)Ã
As(2) 107.5(3), N(1)ÃAs(1)ÃN(2) 107.0(3), N(1)ÃAs(1)ÃC(25) 105.2(3), N(2)ÃAs(1)ÃC(25) 98.7(3), N(3)ÃAs(2)ÃN(4) 107.1(3), N(3)ÃAs(2)ÃC(25)
104.5(3), N(4)ÃAs(2)ÃC(25) 100.0(3); (e) structure of 5 showing orientation of weak dimer pairs. As(1)ÃC(21) 1.972(4), As(1)ÃS(1) 2.2802(14),
As(1)ÃS(2) 2.267(2), As(2)ÃC(21) 1.975(4), As(2)ÃS(3) 2.279(2), As(2)ÃS(4) 2.267(2), As(1)ÃC(21)ÃAs(2) 115.9(2), S(1)ÃAs(1)ÃS(2) 85.19(6), S(1)Ã
As(1)ÃC(21) 99.78(13), S(2)ÃAs(1)ÃC(21) 99.04(14), S(3)ÃAs(2)ÃS(4) 91.04(6), S(3)ÃAs(2)ÃC(21) 97.31(13), S(4)ÃAs(2)ÃC(21) 92.88(14).
/
5 showing important bond lengths (A) and angles (8). H-atoms and selected (chemically non-important) C
C(1) 2.155(6), Sb(1)ÃC(11) 2.096(7), C(11)ÃC(12) 1.198(9), C(3)ÃC(4) 1.200(10),
Sb(1)ÃC(1) 95.4(2); (b) molecular structure of 2. As(1)Ã
C(1) 1.976(6), As(1)ÃC(11) 1.912(7), As(1)Ã
As(1)ÃC(6) 97.5(2), C(11)Ã
/
/
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C(1)
C(6)
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As(1)Ã
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M.A. Paver et al. / Polyhedron 22 (2003) 211Á
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213
Fig. 1 (Continued)
2. Experimental
vacuo and the product was extracted using C6H5CH3.
The mixture was filtered through celite to remove LiCl
and the product was then crystallised from approxi-
2.1. General procedure
1
mately 20 ml of Et2O (65%). H NMR (C6D6): 1.45 (t,
4H, SbÃ
/
CH2Ã
/
), 2.85 (qn, 2H, Ã
/
CH2Ã
/
), 6.8Á7.2 (m,
/
The products 1, 2, 3, 4, 5, the starting materials
Cl2Sb(CH2)3SbCl2, Cl2AsCH2AsCl2 and nBuLi are all
air and/or moisture sensitive. They were handled on a
vacuum line using standard inert atmosphere techniques
under dry and oxygen-free N2. The C6H5CH3, C6H14,
Et2O and THF solvents were dried using sodium/
benzophenone and were degassed prior to their use in
reactions. The hexamethyldisilazane and trimethylsily-
20H, phenyl). C, H, N: Anal. Found: C, 59.8; H, 3.7.
Calc. for C35H26Sb2: C, 60.9; H, 3.8%.
2.3. Synthesis of 2
A solution of 1.021 g (10 mmol) of PhCÅ
Et2O was stirred at ꢃ78 8C and 6.25 ml (10 mmol, 1.6
/CH in 40 ml
/
lacetylene were dried using molecular sieve (13ꢂ
/
). The
M sol.) of nBuLi was added. This mixture was stirred for
approximately 30 min and allowed to warm back to r.t.
The solution obtained was then cooled to 0 8C and to it
was added a solution of 0.764 g (2.5 mmol) of
Cl2AsCH2AsCl2 in Et2O. The reaction was allowed to
stir for 2 h and the Et2O then removed in vacuo. The
product was extracted using C6H5CH3 (40 ml) and
filtered through celite (to remove LiCl), then recrystal-
lised in 15 ml of C6H5CH3. Storage overnight at 5 8C
celite used for filtration was previously dried at 120 8C
for 2 days. All complexes were isolated and charac-
terised with the aid of an N2 filled glove box (Belle
Technology) fitted with an O2 and H2O recirculation
system. Elemental analyses were performed by firstly
sealing samples under Ar in airtight aluminium boats
1
2 mg). H NMR spectra were recorded on Bruker
(1Á
/
AM 300MHz spectrometer in dry d6 C6H6 (using the
solvent resonances as the internal reference standard
yielded colourless needles (40%). 1H NMR (C6D6): 6.8Á
/
and are reported in
d
ppm). Samples of
7.4 (m, phenyl). C, H, N: Anal. Found: C, 74.2; H, 4.0.
Calc. for C24H15As1: C, 76.2; H, 4.0%.
Cl2Sb(CH2)3SbCl2 and Cl2AsCH2AsCl2 were prepared
in accordance with the previously reported methods
[11,12].
2.4. Synthesis of 3
2.2. Synthesis of 1
A solution of 0.982 g (10 mmol) of Me3SiCÅ
/
CH in 20
ml of C6H5CH3 was reacted at ꢃ
/
78 8C with 6.25 ml (10
A solution of 0.409 g (4 mmol) of PhCÅ
/
CH in 20 ml
of Et2O was reacted with 2.5 ml of BuLi (4 mmol, 1.6
M sol.) at ꢃ78 8C. The reaction was then stirred at
mmol, 1.6 M sol.) of nBuLi with stirring and the
reaction mixture was allowed to warm to r.t. over a
further 30 min. The resultant colourless solution was
n
/
room temperature (r.t.) for approximately 30 min. The
colourless solution obtained was then cooled to 0 8C
and a solution of 0.427 g (1 mmol) of Cl2Sb(CH2)3SbCl2
in C6H5CH3 was added. The mixture was allowed to
react at r.t. for 2 h after which time the Et2O removed in
cooled to 0 8C and 0.764
g
(2.5 mmol) of
Cl2AsCH2AsCl2 was added and the mixture stirred at
r.t. for approximately 30 min. The white precipitate of
LiCl was removed by filtration through celite to yield a
colourless solution. This was reduced to dryness in

214
M.A. Paver et al. / Polyhedron 22 (2003) 211Á216
/
vacuo, and 20 ml of C6H14 added to dissolve the residue.
Reduction in vacuo to approximately 5 ml yielded a
white precipitate which redissolved upon gentle warm-
ing. Storage at 5 8C overnight produced a crop of
colourless crystalline blocks of 3 in 75% yield. 1H
hydrogen atoms were located in the difference map and
refine isotropically. For compounds 2, 3, 4 and 5 the
hydrogen atoms were included in idealised positions
˚
H set at distances between 0.950 and 0.990 A
with CÃ
/
and with isotropic thermal parameters set at 1.2 times
that of the carbon atom to which they were attached.
Details of the structural solutions and crystal informa-
tion for 1, 2, 3, 4 and 5 are presented in Table 1.
NMR (C6D6): 0.07 (s, 36H, Me), 2.07 (s, 2H, AsÃ
/
CH2Ã
/
As). C, H, N: Anal. Found: C, 45.2; H, 6.8.
Calc. for C21H38As2Si4: C, 45.7; H, 6.9%.
Diagrams of the five structures are given as Fig. 1(aÁe).
/
2.5. Synthesis of 4
An identical procedure to the synthesis of 3 was
employed utilising 1.614 g (10 mmol) of (Me3Si)2NH
and 6.25 ml (10 mmol, 1.6 M sol.) of nBuLi. The
product was again isolated as colourless crystalline
blocks from C6H14 solution in 70% yield. 1H NMR
3. Results and discussion
The five compounds reported represent significant
additions to the polynuclear arsine and stibine ligands
available to coordination chemists, and we have demon-
strated that it is possible to readily add functionalised
organic groups onto the metal centres. Compound 1 is
an example of a binuclear organo-functionalised stibine
and comparison with the previously reported structure
of Ph2Sb(CH2)3SbPh2 reveals a similar structural motif
(Fig. 1a) [19]. The pyramidal angles about the antimony
(C6D6): 0.08 (s, 72H, Me), 2.51 (s, 2H, AsÃ
/
CH2Ã
/
As). C,
H, N: Anal. Found: C, 36.8; H, 9.2; N, 6.8. Calc. for
C25H74As2N4Si8: C, 37.2; H, 9.2; N, 7.0%.
2.6. Synthesis of 5
A solution of 1.112 g (10 mmol) of 2-PySH in 10 ml of
THF was reacted at 0 8C with 6.25 ml (10 mmol) of
nBuLi and allowed to warm to r.t. over approximately
30 min to yield a pale yellow solution. After chilling to
centres range from 94.8(3)8Á
/
96.58(2) compared to
94.4(1)8Á98.78(1) for Ph2Sb(CH2)3SbPh2. During the
/
synthesis of compound 2 (Fig. 1b) the methylene bridge
between the arsenic centres has broken (Scheme 1). This
behaviour in relation to the other four examples is a
noticeable exception. However, previous work on the
AsCH2As backbone had led us to investigate this
cleavage before. Thus, it has been noted that during
ꢃ78 8C, 0.764 g (2.5 mmol) of Cl2AsCH2AsCl2 was
/
added and the reaction mixture stirred for 30 min at r.t.
to yield a yellow solution. This was reduced to dryness
in vacuo and the product extracted into 20 ml of hot
C6H5CH3. Filtration through celite (to remove LiCl)
yielded a lemon yellow solution, which upon reduction
in vacuo to approximately 12 ml yielded a yellow
precipitate. This readily redissolved upon heating and
storage at 5 8C overnight produced a crop of lemon
yellow crystals of 5 in 75% yield. 1H NMR (C6D6): 2.28
the formation of benzo 1,3,2 diazaarsolyl lithium×
/2THF
from the reaction of 1,2-LiHNÃ2-NH2C6H4 with (Me2-
/
N)2AsCH2As(NMe2)2 (4:1 equiv.) the methylene bridge
in the precursor is broken during the course of the
reaction [5]. Once again the carbon backbone here has
broken during synthesis, creating a mononuclear trisa-
cetylide species. Further investigation of the reaction
mother liquor did not yield any readily identifiable
arsenic or methyl-arsine species. However, it is reason-
able to assume that the mother solution is likely to
contain a second, as yet unidentified, arsenic species.
Efforts are continuing to identify these products and
also, therefore, to provide a better understanding of the
reaction mechanism. It should also be noted that
following the synthesis of this acetylide from the di-
nuclear precursor the same reaction was attempted using
AsCl3 instead of the diarsine, leading to an enhanced
yield of 2 as the only product. In contrast to this,
compounds 3, 4 and 5 are all synthesised from the
dinuclear precursor and maintain their framework
during the synthesis. There is no clear rationale behind
this, but as noted with previous work, the cleavage of
such bridges is possible in the syntheses of related
complexes. It is sufficient at this time to comment that
whether the bridge is likely to break or remain intact
depends solely on the reaction constituents and the
(s, 2H, AsÃ
/
CH2Ã
/
As), 7.15Á7.62 (m, 16H, pyridyl
/
groups). C, H, N: Anal. Found: C, 41.1; H, 3.1; N,
9.0. Calc. for C21H18As2N4S4: C, 41.7; H, 3.0; N, 9.3%.
2.7. X-ray crystallography
Data for 1 and 2, were collected in an EnrafÁNonius
/
KappaCCD area detector diffractometer whilst 3, 4 and
5 were collected on a AFC5 Rigaku diffractometer, both
fitted with Mo Ka radiation and a graphite monochro-
mator. All compounds are air sensitive and were kept
under a flow of nitrogen at 150 K for 1Á4 and 180 K for
/
5; data collection and cell refinement [13] gave the cell
dimensions shown in Table 1. For 1 and 2 a multi-
reflection absorption correction [14,15] was applied and
for 3, 4 and 5 a semiempirical absorption correction
based on psi-scans was applied. The data solved via
direct methods [16] and the structures refined using the
WINGX [17] version of SHELXS-97 [18]. All non-
hydrogen atoms were treated anisotropically. In 1 the

M.A. Paver et al. / Polyhedron 22 (2003) 211Á
/216
215
Table 1
Crystal data and structure solution of 1,3-[(PhCÅC)2Sb]2(CH2)3 (1), As(CÅCPh)3 (2) [(Me3SiCÅC)2As]2CH2 (3), {[(Me3Si)2N]2As2}CH2 (4), [(2-
SPy)2As]2CH2 (5)
1
2
3
4
5
Empirical formula
M
C35H26Sb2
690.06
150(2)
C24H15As1
378.28
150(2)
C21H38As2Si4
552.71
150(2)
C25H74As2N4Si8
805.44
150(2)
C21H18As2N4S4
604.47
180(2)
T (K)
Wavelength (A)
˚
0.71073
monoclinic
C2
0.71073
trigonal
R3
0.71069
monoclinic
P21/c
0.71069
monoclinic
P21/n
0.71069
triclinic
¯
P1/
Crystal system
Space group
/
˚
a (A)
19.054(4)
5.5344(11)
13.790(3)
18.6408(15)
18.6408(15)
4.4235(7)
90
11.581(5)
16.681(5)
16.406(5)
12.901(5)
19.307(3)
18.405(3)
9.725(3)
˚
b (A)
14.576(4)
8.545(4)
93.58(3)
˚
c (A)
a (8)
b (8)
g (8)
91.94(3)
90
120
110.029(5)
101.39(2)
90.85(4)
103.34(2)
1175.8(7)
2
3
˚
U (A )
Z
1453.4(5)
2
1.577
1331.1(3)
3
1.416
2978(2)
4
1.233
4494(2)
4
1.190
Dc (Mg mꢃ3
u Range
)
1.707
2.145u 527.45
0.25ꢂ0.02ꢂ0.02
6022
3.795u 525.03
0.1ꢂ0.02ꢂ0.02
2363
2.645u 525.01
0.2ꢂ0.1ꢂ0.1
5506
2.655u 522.51
0.3ꢂ0.25ꢂ0.22
6152
2.705u 527.54
0.3ꢂ0.2ꢂ0.15
5669
Crystal size (mm)
Reflections collected
Independent reflections
Goodness-of-fit on F2
R indices [F ꢀ4s(F)]: R1, wR2
R indices (all data): R1, wR2
3010
0.733
955
1.072
5233
1.028
5849
1.009
5354
1.027
0.0399, 0.0984
0.0507, 0.1088
1.408, ꢃ0.891
192078
0.0536, 0.1260
0.0579, 0.1290
0.659 ꢃ0.847
192077
0.0563, 0.1140
0.0991, 0.1327
0.718, ꢃ0.800
192080
0.0536, 0.1057
0.1518, 0.1800
0.521, ꢃ0.575
192081
0.0458, 0.0917
0.0750, 0.1035
0.497, ꢃ0.653
192079
ꢃ3
˚
Final difference peak and hole (e A
CCDC number
)
stability of the potential products formed. Compounds
3, 4 and 5 all appear to be similar in nature, however,
there are significant structural differences. For 3 (Fig.
1c) the addition of four acetylide groups is as expected.
Comparison of the angles around the arsenic centres
with those obtained from 2 and other literature [16]
diarsine compounds reveals that the angles are very
similar. This tends to indicate that, as expected, the
sterically non-bulky acetylide groups do not have any
noticeable influences on the ideally pyramidal arsenic
centres. The AsÃ
/
CH2ÃAs angle (115.38) is also within
/
the expected angle given the literature values available
(for Ph2AsCH2AsPh2 the angle about bridging methyl-
ene 113.338) [20Á22]. The more sterically bulky
/
Scheme 1.

216
M.A. Paver et al. / Polyhedron 22 (2003) 211Á216
/
Ã
/
N(SiMe3)2 groups in 4 (Fig. 1d) contribute signifi-
pounds 1, 2, 3, 4 and 5. Copies of this information may
be obtained free of charge from The Director, CCDC,
cantly to a distorted pyramidal geometry around the
arsenic atoms (angles about arsenic centres, As(1)
12 Union Road, Cambridge, CB2 1EZ, UK (fax: ꢄ44-
/
98.7(3)8Á
/
107.0(3), As(2) 100.0(3)8Á
/
107.1(3)8) and an
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
expected trigonal planar arrangement around the sp2
nitrogen atoms. Most significantly though is the angle of
107.5(3)8 about the bridging methylene group. Unlike
the other methylene bridged examples both here and in
the literature, the angle is smaller than the uncoordi-
nated or monodentate complexes published. Several
transition metal complexes incorporating bidentate
Acknowledgements
We wish to acknowledge the EPSRC for project
studentship (J.S.J) and the provision of crystallographic
equipment.
chelation of the AsÃ
geometry (90.48Á97.18) [23Á
/
CH2Ã
/
As moiety possess a strained
/
/25], however, this is to be
expected given the geometrical constraints of the four
membered rings formed. Since 4 is a free ligand this
restricted geometry is almost certainly a result of steric
effects due to the arrangement of the ligands around the
arsenic centres. For compound 5 another type of
structural arrangement is observed, involving partial p-
stacking of the aromatic pyridyl groups. The molecule
can be split into two with regards to the geometry. The
References
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[3] M.A. Beswick, M.E.G. Mosquera, D.S. Wright, J. Chem. Soc.,
Dalton Trans. (1998) 2437.
angles about As(2) (S(3)Ã
As(2)ÃC(21) 97.31(13), S(4)Ã
are consistent with those seen in the literature and in 2
and 3. The angle of the methylene bridge (As(1)ÃC(21)Ã
/
As(2)Ã
/
S(4) 91.04(6), S(3)Ã
/
[4] M.A. Beswick, M.K. Davies, C.N. Harmer, A.D. Hopkins,
M.E.G. Mosquera, J.S. Palmer, M.A. Paver, P.R. Raithby, D.S.
Wright, Phosporus, Sulfur, Silicon Relat. Elem. 125 (1997) 103.
[5] M.A. Paver, J.S. Joy, M.B. Hursthouse, Chem. Commun. (2001)
2480.
/
/
As(2)Ã
/
C(21) 92.88(14)8)
/
/
As(2) 115.98) is also consistent with a non-sterically
hindered methylene arsine compound [20]. However, the
geometry is significantly different around As(1). Here
the angles are no longer consistent with a traditional
[6] S.J. Coles, M.B. Hursthouse, J.S. Joy, M.A. Paver, J. Chem. Soc.,
Dalton Trans. (2000) 3239.
[7] R.J. Puddephatt, Chem. Soc. Rev. 12 (1983) 99.
[8] B. Chaudret, B. Delavaux, R. Poilblanc, Coord. Chem. Rev. 86
(1988) 191.
pyramidal geometry, in particular the S(2)Ã
/
As(1)Ã
/
S(1)
[9] N.R. Champness, W. Levason, Coord. Chem. Rev. 133 (1994)
115.
angle of 85.198 is particularly small compared to the
other angles. This distortion is a result of intermolecular
[10] V.F. Kober, Z. Anorg. Allg. Chem. 412 (1975) 202.
[11] Y. Matsumura, R. Okawara, Inorg. Nucl. Chem. Lett. 7 (1971)
113.
pÁp stacking between the pyridyl groups on one end of
/
two separate diarsine molecules. This in effect forms a
pseudo-dimeric structure (Fig. 1e) since only one half of
[12] K. Sommer, Anorg. Allg. Chem. 377 (1970) 120.
[13] Z. Otwinowski, W. Minor, Macromolecular Crystallography,
part A, in: C.W. Carter, Jr., R.M. Sweet (Eds.), Methods in
Enzymology, vol. 276, Academic Press, New York, 1997.
[14] R.H. Blessing, J. Appl. Crystallogr. 30 (1997) 427.
[15] R.H. Blessing, Acta Crystallogr., Sect. A 51 (1995) 33.
[16] G.M. Sheldrick, Acta Crystallogr., Sect. A 46 (1990) 467.
[17] L.J. Farrugia, J. Appl. Crystallogr. 32 (1999) 837.
each diarsine is involved in pÁ
p-stacking is common place in organic structures and it
is widely recognised that the centroidÁcentroid distance
between the rings must be within the range 3.3Á
[26]. Here the centroidÁcentroid distance is 3.855 A,
which although at the upper limit, does represent a
realistic pÁp interaction especially when related to the
/
p stacking. The effect of
/
˚
3.8 A
/
˚
/
[18] G.M. Sheldrick, SHELXL-97, University of Gottingen, Gottingen,
¨ ¨
/
Germany.
[19] A.M. Hill, W. Levason, M. Webster, I. Albers, Organometallics
16 (1997) 5641.
observed distortions. It is intended to use the potential
selective reactivities of these substituted arsine and
stibine ligands to generate a host of mixed-metal
compounds incorporating s-/d- and p-block metals.
[20] A.J Canty, B.M. Gatehouse, J. Chem. Soc., Dalton Trans. (1972)
511.
[21] H.-K. Fun, O.B. Shawkataly, S.-G. Teoh, Acta Crystallogr., Sect.
C 46 (1990) 2329.
[22] A.F. Chiffrey, J. Evans, W. Levason, M. Webster, Polyhedron 15
(1996) 591.
4. Supplementary material
[23] M.G.B. Drew, A.P. Wolters, Acta Crystallogr., Sect. B 33 (1977)
205.
Atomic coordinates, bond lengths and angles, and
thermal parameters have been deposited with the Cam-
bridge Crystallographic Data Centre, CCDC Nos.
192078, 192077, 192080, 192081 and 192079 for com-
[24] M.G.B. Drew, J. Chem. Soc., Dalton Trans. (1972) 626.
[25] M.G.B. Drew, A.P. Wolters, I.B. Tompkins, J. Chem. Soc.,
Dalton Trans. (1977) 974.
[26] C.J. Janiak, J. Chem. Soc., Dalton Trans. (2000) 3885.