Inclusion properties of 1,4-(triorganostannyl and -silyl)buta-1,3-diynes: Thermal, structural, and NMR spectroscopic aspects

Article abstract of DOI:10.1021/om9804430

The tin-containing diyne Ph₃SnC≡CC≡CSnPh₃ (4) forms 1:1 host-guest complexes with a large variety of organic molecules. These complexes have been characterized by ¹H NMR spectroscopy, thermogravimetry (TGA), and differential scanning calorimetry (DSC). Weak interactions between the host and guest molecules are observed with toluene, tetrachloroethane, and p-xylene (the latter gives a 2:1 complex). Strong interactions are found with dichloromethane, chloroform, tetrahydrofuran, and dioxane. An intermediate behavior is observed with acetone, benzene, and pyridine. Guest-selectivity studies have been carried out on some of these complexes that confirm the results obtained from the TGA measurements. A single-crystal X-ray diffraction analysis of 4:dioxane shows that it has a true clathrate (cage) structure with the guest molecule being surrounded by 12 phenyl groups from 6 Ph₃Sn moieties. Inclusion compounds do not form when the length of the spacer is shortened, i.e. with Ph₃SnC≡CSnPh₃, or when the SnPh₃ groups of 4 are replaced by SnMe₃ moieties. On going from Ph₃SnC≡CC≡CSnPh₃ to Ph₃Sn(CH₂)₄SnPh₃, i.e. when the rigid diacetylene fragment is replaced by the flexible butanediyl group, formation of a clathrate is observed only in the case of dioxane. When Ph₂PC≡CC≡CPPh₂ or Ph₃SiC≡CC≡CSiPh₃ is used as host instead of Ph₃SnC≡CC≡CSnPh₃, there is no evidence for clathrate formation. However, in the case of Ph₃SiC≡CC≡CSi*MePhNp (5: Np = 1-naphthyl), a 1:1 clathrate is obtained with dioxane. A single-crystal X-ray diffraction analysis of the 5:dioxane inclusion compound shows that the guest molecule lies exclusively in channels formed by phenyl substituents from the Ph₃Si groups. Solid-state ¹³C, ¹¹⁹Sn, and ²⁹Si NMR and X-ray powder diffraction analyses have been carried out on 4:CHCl₃, 4:dioxane and 5:dioxane prior to and after removal of the guest molecules, and the results demonstrate the structure-stabilizing ability of these molecules. It has been possible to obtain single crystals of 4 with no included solvent, and the X-ray crystal structure of this material shows that the organization of the diacetylenic compound is such that it leads to a more compact packing as compared to that found in 4:dioxane.

Full text of DOI:10.1021/om9804430

770
Organometallics 1999, 18, 770-781
In clu sion P r op er ties of 1,4-(Tr ior ga n osta n n yl a n d
-silyl)bu ta -1,3-d iyn es: Th er m a l, Str u ctu r a l, a n d NMR
Sp ectr oscop ic Asp ects
Francis Carre´, Sylvain G. Dutremez,* Christian Gue´rin,* Bernard J . L. Henner,*
Agne`s J olivet, and Ve´ronique Tomberli
Laboratoire “Chimie Mole´culaire et Organisation du Solide”, UMR 5637, Universite´
Montpellier II, Case 007, Place E. Bataillon, 34095 Montpellier Cedex 5, France
Franc¸oise Dahan
Laboratoire de Chimie de Coordination du CNRS, UPR 8241, lie´e par conventions a`
l’Universite´ Paul Sabatier et a` l’Institut National Polytechnique de Toulouse,
205 route de Narbonne, 31077 Toulouse Cedex 4, France
Received J une 1, 1998
The tin-containing diyne Ph3SnCtCCtCSnPh3 (4) forms 1:1 host-guest complexes with
1
a large variety of organic molecules. These complexes have been characterized by H NMR
spectroscopy, thermogravimetry (TGA), and differential scanning calorimetry (DSC). Weak
interactions between the host and guest molecules are observed with toluene, tetrachloro-
ethane, and p-xylene (the latter gives a 2:1 complex). Strong interactions are found with
dichloromethane, chloroform, tetrahydrofuran, and dioxane. An intermediate behavior is
observed with acetone, benzene, and pyridine. Guest-selectivity studies have been carried
out on some of these complexes that confirm the results obtained from the TGA measure-
ments. A single-crystal X-ray diffraction analysis of 4:dioxane shows that it has a true
clathrate (cage) structure with the guest molecule being surrounded by 12 phenyl groups
from 6 Ph3Sn moieties. Inclusion compounds do not form when the length of the spacer is
shortened, i.e. with Ph3SnCtCSnPh3, or when the SnPh3 groups of 4 are replaced by SnMe3
moieties. On going from Ph3SnCtCCtCSnPh3 to Ph3Sn(CH2)4SnPh3, i.e. when the rigid
diacetylene fragment is replaced by the flexible butanediyl group, formation of a clathrate
is observed only in the case of dioxane. When Ph2PCtCCtCPPh2 or Ph3SiCtCCtCSiPh3
is used as host instead of Ph3SnCtCCtCSnPh3, there is no evidence for clathrate formation.
However, in the case of Ph3SiCtCCtCSi*MePhNp (5: Np ) 1-naphthyl), a 1:1 clathrate is
obtained with dioxane. A single-crystal X-ray diffraction analysis of the 5:dioxane inclusion
compound shows that the guest molecule lies exclusively in channels formed by phenyl
substituents from the Ph3Si groups. Solid-state 13C, 119Sn, and 29Si NMR and X-ray powder
diffraction analyses have been carried out on 4:CHCl3, 4:dioxane and 5:dioxane prior to and
after removal of the guest molecules, and the results demonstrate the structure-stabilizing
ability of these molecules. It has been possible to obtain single crystals of 4 with no included
solvent, and the X-ray crystal structure of this material shows that the organization of the
diacetylenic compound is such that it leads to a more compact packing as compared to that
found in 4:dioxane.
In tr od u ction
inhibits close packing of the molecules. Voids are created
where solvent molecules can nest.
Diacetylenic compounds with bulky end groups, com-
monly called wheel-and-axle molecules, can act as hosts
in clathrate structures.1-4 The diacetylenic moiety is a
rigid spacer that keeps the bulky groups apart and
Diynes 1, in which no strongly polar groups are
present, have been found to give host-guest complexes
with benzene, toluene, xylenes, and chloroform.5
* To whom correspondence should be addressed. Fax: (33) 4 67 14
38 52. E-mail: bhenner@crit.univ-montp2.fr.
Ar3CCtCCtCCAr3
1
(1) (a) Molecular Inclusion and Molecular Recognition-Clathrates I;
Weber, E., Ed.; Topics in Current Chemistry 140; Springer-Verlag:
Berlin, Germany, 1987. (b) Molecular Inclusion and Molecular Recog-
nition-Clathrates II; Weber, E., Ed.; Topics in Current Chemistry 149;
Springer-Verlag: London, U.K., 1988. (c) Vo¨gtle, F. Supramolecular
Chemistry: An Introduction; Wiley: Chichester, U.K., 1991; p 187.
(2) Toda, F.; Akagi, K. Tetrahedron Lett. 1968, 3695.
Ar3 ) Ph3, Ph2(p-biphenyl), Ph(p-biphenyl)2,
(p-biphenyl)3
(3) Toda, F. Pure Appl. Chem. 1990, 62, 417.
(4) Toda, F.; Ward, D. L.; Hart, H. Tetrahedron Lett. 1981, 22, 3865.
(5) Hart, H.; Lin, L.-T. W.; Ward, D. L. J . Am. Chem. Soc. 1984,
106, 4043.
10.1021/om9804430 CCC: $18.00 © 1999 American Chemical Society
Publication on Web 01/27/1999

1,4-(Triorganostannyl and -silyl)buta-1,3-diynes
Organometallics, Vol. 18, No. 4, 1999 771
A structural study of the 1:1 complex between (p-
biphenyl)Ph2CCtCCtCCPh2(p-biphenyl) and p-xylene
indicates that CH‚‚‚π interactions are the predominant
interactions in these clathrates: such contacts may be
found between the guest molecule and the aryl groups
from the host and, also, are the way by which aryl
groups from neighboring host molecules interact with
one another.5,6
The distance between the bulky end groups of the host
may be increased. For instance, Ph3C(CtC)3CPh3 forms
a stable 1:1 complex with p-xylene and somewhat less
stable complexes with benzene, toluene, o-xylene, and
chlorobenzene.5
To analyze the influence of the rigid molecular axis
on clathrate formation, sp2- and sp3-hybridized carbons
were incorporated in the structure and it was found that
the new compounds still functioned as hosts toward
toluene and xylenes. For instance, the following clath-
rates were obtained:5
rate 3:d-3-methylcyclohexanone (1:2), which liberates
d-3-methylcyclohexanone upon heating.
On the basis of these results, we decided to investigate
the inclusion properties of diacetylene compounds pos-
sessing heteroelement-containing groups such as SiR3,
SnR3, and PPh2. These heteroelements are larger than
carbon and may favor the creation of voids in the crystal,
possibly leading to novel structural types. Furthermore,
the differences that exist in their electronic properties
and the panel of substituents available with these
heteroelements make these derivatives attractive.
Only one short paper has appeared in the literature
concerning the structure of a tin-containing clathrate,
namely 1,4-bis(triphenylstannyl)buta-1,3-diyne (4):chlo-
roform (1:1), which was determined by single-crystal
X-ray diffraction.9 The lead analogue of 4 gives an
inclusion complex with dichloromethane.9
In this paper we generalize the inclusion properties
of 4; i.e., we study clathrate formation from it and
determine the stability of the host-guest complexes via
thermogravimetric analysis (TGA) and selectivity stud-
ies. A study of the relationship between 13C and 119Sn
solid-state NMR results and X-ray powder diffraction
data is presented that demonstrates the templating
effect of the guest molecule. The solid-state structure
of 4:dioxane is also reported, and it is compared with
that of the unsolvated material. Steric and electronic
factors are evaluated by changing (i) the substituents
attached to the heteroelement (aryl or methyl), (ii) the
nature of the heteroelement (Si, Sn, P), and (iii) the
length and rigidity of the spacer between the two
heteroelements.
Ph3CCHdCHCHdCHCPh3:toluene (3:1)
Ph3CCH2CHdCHCH2CPh3:toluene (1:1)
Ph3C(CH2)4CPh3:toluene (1:1)
In this series of compounds, all of those that were
characterized by crystallography were of the channel
type, meaning that, to some degree, the nature of the
central part of the host and the type of guest have only
little impact on the structure of the clathrate. The key
feature seems to be the bulkiness of the end groups and
the way they interact with one another. The organiza-
tion of the clathrate is also dependent on interactions
that exist between the guest molecule and the host: it
was observed that the plane of the toluene ring in the
channel was not random but was involved in CH‚‚‚π
interactions with phenyl substituents from the host.5,6
These interactions undoubtedly contribute to the stabil-
ity of the host-guest complexes.
CH‚‚‚π contacts may be found with groups other than
aromatics. Thus, such interactions have recently been
observed by Mu¨ller et al. in the case of the 1:2 host-
guest complex bis[(naphthyldiphenylphosphino)gold]-
acetylene-chloroform;7 these involve the weakly acidic
hydrogen of the chloroform molecule and the electron-
rich triple bond.
Resu lts a n d Discu ssion
1. F or m a tion , Ch a r a cter iza tion a n d Sta bility of
th e Host-Gu est Com p lexes. Ph3SnCtCCtCSnPh3
(4) was dissolved in various organic solvents (benzene,
dioxane, chloroform, etc.) and allowed to crystallize (see
Experimental Section). Compound 4 does not come out
of solution when N,N-dimethylformamide (DMF) and
dimethyl sulfoxide (DMSO) are used to dissolve it, even
though it is only sparingly soluble in these solvents. A
119Sn NMR spectroscopic study of the DMF and DMSO
solutions indicates that the structure of 4 is unchanged
in these solvents (δ(119Sn(DMF)) -185.6 and δ(119Sn-
(DMSO)) -205.4 ppm). Diyne 4 is not soluble in ethanol.
With mesitylene, the crystals that formed showed no
inclusion of solvent. In all of the other cases, the crystals
that were obtained corresponded to clathrates which
Replacement of an aryl group with an hydroxyl
functionality leads to clathrates where hydrogen bond-
ing is present:2
1
were analyzed by H NMR spectroscopy and TGA. The
results are summarized in Table 1.
Ar2C(OH)CtCCtC(OH)Ar2
Compound 4 is capable of including a large variety of
molecules, e.g. halogenated hydrocarbons (dichloro-
methane, chloroform, 1,1′,2,2′-tetrachloroethane, and
2-chloropropane), polar molecules (acetone, tetrahydro-
furan, dioxane, and acetonitrile), and aromatic solvents
(benzene, toluene, p-xylene, and pyridine).
The stoichiometry observed in these clathrates is
typically 1:1. One exception is the 4:p-xylene complex,
for which the host-guest ratio is 2:1. As the steric
demand of the guest molecule increases, as in the case
2
Molecules such as 2 form host-guest complexes that
have found applications in the resolution of racemates.8
Using the optically active host l-1,6-diphenyl-1,6-bis(o-
chlorophenyl)hexa-2,4-diyne-1,6-diol (3), and dl-3-me-
thylcyclohexanone, Toda et al. have obtained the clath-
(6) Cambridge Structural Database. Release date 98/02/02. 181309
entries.
(7) Mu¨ller, T. E.; Mingos, D. M. P.; Williams, D. J . J . Chem. Soc.,
Chem. Commun. 1994, 1787.
(8) Toda, F.; Tanaka, K.; Omata, T.; Nakamura, K.; Oh shima, T. J .
Am. Chem. Soc. 1983, 105, 5151.
(9) Brouty, C.; Spinat, P.; Whuler, A. Acta Crystallogr. 1980, B36,
2624.

772 Organometallics, Vol. 18, No. 4, 1999
Carre´ et al.
Ta ble 1. Stoich iom etr y a n d Th er m a l Sta bility of th e 4:solven t Cla th r a tes As Deter m in ed by 1H NMR
Sp ectr oscop y a n d TGA Mea su r em en ts
TGAa
∆mth,c %
host-guest
solvent
ratio (1H NMR)
∆mobs,b %
∆T,d °C
Tb of solvent, °C
Tf - Tb,e °C
dichloromethane
chloroform
tetrachloroethane
isopropyl chloride
acetone
tetrahydrofuran
dioxane
acetonitrile
benzene
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
1:1
2:1
10.2
13.7
18.5
f
5.7
8.8
10.6
f
9.1
7.1
9.6
6.6
10.2
13.8
18.3
50-110
40
61
147
35
56
66
101
81
80
110
115
138
70
50
-50
55-110
50-95
7.2
8.8
10.5
room temp-65
70-135
80-160
10
70
60
9.5
11.0
9.5
45-100
20
-50
-5
toluene
pyridine
p-xylene
room temp-60
65-110
6.6
70-95
-40
a
b
Thermogravimetric analyses were carried out under argon between 20 and 350 °C with a heating rate of 5 °C/min. Observed weight
losses. c Expected weight losses. Temperature domain for the weight loss. e Difference between the final temperature of the weight loss
d
(Tf) and the boiling point of the guest molecule (Tb). f The solubility of 4 in these solvents is too low, and so enough clathrate could not
be obtained to carry out TGA measurements.
weight loss (Tf) and the boiling point of the guest (Tb).
These values are given in Table 1 and agree well with
the order of stability determined from ∆T values.
The 4:solvent clathrates may be divided into three
classes according to their stability.
(i) Weak interactions (-50 e Tf - Tb e -40) are
observed for the inclusion compounds prepared from 4
and toluene or tetrachloroethane. The release of the
guest occurs in a temperature range that is much lower
than the boiling point of the solvent. Furthermore, the
weight loss observed by TGA for the 4:toluene inclusion
compound is smaller than that expected from H NMR
F igu r e 1. DSC and TGA curves of 4:dioxane.
1
measurements; this is due to partial loss of the solvent
during sample preparation.
of mesitylene, crystals of 4 are obtained without inclu-
sion of a guest.
(ii) Strong interactions (50 e Tf - Tb e 70) are
observed when the weight loss occurs in a large tem-
perature domain that is higher than or barely includes
the boiling point of the solvent. Strong interactions are
observed for the clathrates prepared from dichlo-
romethane, chloroform, tetrahydrofuran, and dioxane.
(iii) An intermediate behavior (-5 e Tf - Tb e 20) is
observed with acetone, benzene, and pyridine. In this
case, the weight loss occurs just below the boiling point
of the solvent or the final temperature is close to that
boiling point.
The 4:p-xylene complex is different from the other
clathrates analyzed in this study, as the host-guest
ratio is 2:1. However, on the basis of the ∆T and Tf -
Tb values, it is clear that this complex belongs to the
first class of compounds, i.e. those with weak host-guest
interactions.
The size of the guest is important. This is illustrated
in the case of the aromatic solvents: with benzene, the
clathrate that is formed is fairly stable but, with toluene,
the stability is much lower. When two methyl groups
are present on the aromatic ring, i.e. in the case of
p-xylene, the nesting of the guest becomes more difficult
and the stoichiometry (and the structure) of the clath-
rate changes. Finally, when mesitylene is used, crystals
are formed that do not include a guest. The same holds
true for the halogenated hydrocarbons used in this
study: it is indeed observed that the stability of the
TGA measurements confirm the stoichiometries de-
termined by H NMR analysis (Table 1). The observed
1
weight losses correspond to the departure of the in-
cluded solvent and take place before the melting of 4
(245 °C). As an example, Figure 1 shows the differential
scanning calorimetry (DSC) and TGA curves of the
4:dioxane complex.
The TGA curve of 4:dioxane shows a weight loss of
10.6% between 80 and 160 °C; the calculated value for
the complete loss of dioxane is 10.5%. The first endo-
therm of the DSC curve indicates that the loss of the
guest molecule occurs in a single step (between 80 and
160 °C), while the second endotherm corresponds to the
melting of the host compound. The exothermic peak
observed at higher temperatures corresponds to the
polymerization of the diacetylene units.
Elemental analyses were carried out on two of the
most stable 4:solvent clathrates, and the results are in
good agreement with the compositions determined by
1H NMR and TGA measurements (see Experimental
Section).
The thermal stability of the host-guest complexes
may be assessed from the DSC and TGA curves.10 The
∆T values (Table 1) corresponding to the temperature
range in which the solvent is lost depends on the boiling
point of the guest molecule and the interactions with
the host. It gives an estimation of the stability of the
clathrates. The stability may also be related to the
difference Tf - Tb between the final temperature of the
4:solvent clathrates decreases in the order CH2Cl2
CHCl3 > CHCl2CHCl2.
>
Isopropyl chloride and acetonitrile behave differently
(10) Bourne, S. A.; Nassimbeni, L. R.; Weber, E.; Skobridis, K. J .
Org. Chem. 1992, 57, 2438.
(Table 1); they are very poor solvents of Ph3SnCtCCt

1,4-(Triorganostannyl and -silyl)buta-1,3-diynes
Organometallics, Vol. 18, No. 4, 1999 773
Ta ble 2. Gu est-Selectivity P r op er ties of Host 4
solvent mixture 50:50 (v/v)
guest
stoichiometry
pentane-chloroform
benzene-acetone
dioxane-p-xylene
chloroform
benzene
dioxane
1:1
1:1
1:1
Ta ble 3. Solid -Sta te 13C a n d 119Sn NMR Da ta of th e
4:CHCl3 a n d 4:d ioxa n e Cla th r a tes
n
δ(13C) (ppm) and J SnC (Hz)
δ(119 Sn)
clathrate C1, C4
C2, C3
Ph
guesta (ppm)
4:CHCl3 82.0
94.3
Cipso 135.0
76.8
-165.2
1J ) 463 2J ) 102 1J ) 600
C3,5 130.0
C2,6 137.7
C4 131.2
4:dioxane 82.5
94.8
Cipso 135.1
67.2
-164.6
1J ) 460 2J ) 97 1J (119Sn) ) 628
1J (117Sn) ) 604
C3,5 130.3
C2,6 137.9
C4 131.5
a
In solution: CHCl3, 77.2 ppm; dioxane, 66.7 ppm.
Ta ble 4. 13C a n d 119Sn NMR Da ta of th e 4:d ioxa n e
Cla th r a te in CDCl3
n
δ(13C) (ppm) and J SnC (Hz)
C1, C4
82.9
C2, C3
Ph
guesta δ(119Sn) (ppm)
67.5 -170.1
95.0
Cipso 136.5
1J ) 492 2J ) 97 1J (119Sn) ) 628
4J ) 7
3J ) 20 1J (117Sn) ) 601
C3,5 129.3
3J (119Sn) ) 61
3J (117Sn) ) 58
C2,6 137.2
F igu r e 2. Solid-state 119Sn MAS NMR spectra of 4: (a)
with included dioxane, observation frequency 149.2 MHz,
number of transients 8008, recycle delay time 10 s, 0 Hz
line broadening, spinning rate 12 kHz; (b) without included
dioxane, observation frequency 74.6 MHz, number of
transients 8736, recycle delay time 10 s, 0 Hz line broaden-
ing, spinning rate 3.7 kHz. Asterisks denote spinning
sidebands.
2J (119Sn) ) 44
2J (117Sn) ) 43
C4 130.2
4J (117/119Sn) ) 13
a
In solution: dioxane, 66.7 ppm.
CSnPh3, and so we were unable to obtain enough
material to carry out TGA measurements on the corre-
sponding clathrates.
tin atoms are crystallographically equivalent. The ob-
served chemical shifts, -164.6 ppm (4:dioxane) and
-165.2 ppm (4:CHCl3) are close together and differ only
slightly from the value measured in CDCl3 (-170.1
ppm) (Table 4). This slight difference indicates that
there are no significant structural changes within the
host molecule on passing from the solid to the dissolved
state; i.e., the tin atoms of the host do not interact with
the guest molecules in the inclusion compounds. Similar
observations have been made in the case of Me3SnCt
CCtCSnMe3 that reinforce this presumption: the
119Sn chemical shift in CDCl3 solution, -59.0 ppm, is
close to those found in the solid state, -61.5 and -62.7
ppm, and we have established (vide infra) that Me3-
SnCtCCtCSnMe3 does not give host-guest complexes
with common laboratory solvents.
To determine if clathrate formation was selective, we
have used mixtures of guest molecules (Table 2).
As shown in Table 2, only one of the two solvents
forms a host-guest complex. The clathrate that is
formed is always the more stable one on the basis of
the results from Table 1: chloroform over pentane,
which is a nonsolvent for 4, benzene over acetone, and
dioxane over p-xylene.
2. Solid -Sta te NMR a n d X-r a y P ow d er Diffr a c-
tion Stu d ies. The interactions that exist in the solid
state between 4 and the guest molecules dioxane and
chloroform were analyzed by solid-state NMR methods.
Indeed, strong interactions between the host and guest
molecules are expected to affect the chemical shifts and
coupling constants of the concerned atoms.11 The clath-
rates were also studied by X-ray powder diffraction.
The solid-state 119Sn and 13C NMR data of 4:dioxane
and 4:CHCl3 are listed in Table 3, and Table 4 gives
the values observed in CDCl3 solution. The 119Sn and
13C NMR spectra of the 4: dioxane complex are shown
in Figures 2a and 3a.
The solid-state 13C NMR spectra of 4:dioxane and
4:chloroform display sharp lines with nearly the same
chemical shifts for the acetylenic carbons. These chemi-
cal shifts are close to the values observed in solution,
meaning that, if some interactions exist between the
solvent and the host, they are the same in solution and
in the solid state or that these interactions are weak.
The X-ray powder patterns of 4:dioxane (Figure 4) and
4:CHCl3 are identical and show sharp lines indicative
of good crystallinity and similar structures for the two
clathrates.
In the solid-state 119Sn NMR spectra (Table 3), only
one signal is observed, meaning that, in both cases, the
(11) Klinowski, J . Chem. Rev. 1991, 91, 1459.

774 Organometallics, Vol. 18, No. 4, 1999
Carre´ et al.
Ta ble 5. Solid -Sta te 13C a n d 119Sn NMR Da ta for
th e 4:CHCl3 a n d 4:d ioxa n e Cla th r a tes a fter
Rem ova l of th e Gu est Molecu les
n
δ(13C) (ppm) and J SnC (Hz)
δ(119Sn) (ppm)
and rel intens
clathrate
C1, C4
C2, C3
Ph
4:CHCl3
80.2
81.7
82.5
83.6
84.6
81.4
82.8
83.7
84.9
85.9
91.3
92.5
93.4
94.6
a
93.6
94.6
95.7
a
Cipso 133.6
1J ) 605
C3,5 128.9
C2,6 136.4
C4 130.8
-158.7 (10)
-160.8 (8)
-163.0 (2)
-175.9 (1)
4:dioxane
Cipso 135.4
1J ) 610
C3,5 129.8
C2,6 137.3
C4 131.3
-159.1 (10)
-161.3 (6)
-163.4 (2)
-176.1 (1)
a
Additional ill-defined resonances are observed in the spectrum.
ties, suggestive of tin atoms in four different types of
environments instead of just one as observed in the case
of the clathrates. This complexity is also evident in the
solid-state 13C NMR spectra: a minimum of three well-
defined resonances are observed for each acetylenic
carbon. The symmetry of the molecule is completely lost
after removal of the guest molecule from the clathrate.
This is confirmed by an X-ray diffraction analysis of the
dried material (Figure 4) that shows the loss of crystal-
linity of the sample. These results demonstrate that the
guest molecule acts as a “template” in the crystal
structure; its removal destroys the organization of the
crystal lattice. This is in sharp contrast with what is
observed in the case of clathrasils.12 These data also
show how powerful solid-state NMR is in providing
information about the organization and the structure
of inclusion compounds.13 This conclusion is further
exemplified in the case of Ph3SiCtCCtCSi*MePhNp:
dioxane (5; Np ) 1-naphthyl) (vide infra).
3. Sin gle-Cr ysta l X-r a y Diffr a ction An a lysis of
P h 3Sn CtCCtCSn P h 3:dioxan e. The ZORTEP14 draw-
ing of the host part of the 4:dioxane complex is shown
in the Supporting Information, and the corresponding
crystal data are summarized in Table 6. The crystal
structure of 4:dioxane is centrosymmetric with inversion
centers located at the center of the diacetylene unit, i.e.
between C8 and C8′, and at the center of the dioxane
molecule. It also has 3-fold symmetry with the C3 axis
passing through the four acetylenic carbons and the two
tin atoms. The SnPh3 moieties are propeller-shaped.
Full lists of bond lengths and angles are given in the
Supporting Information. The lengths of the triple bonds
(1.186(4) Å) and the single bond (1.417(6) Å) are close
to those found in related diacetylenic molecules.9,15,16
The unit cell consists of four Ph3SnCtCCtCSnPh3
units and four dioxane molecules. The origin of the cell
was chosen so as to place the center of one of the dioxane
F igu r e 3. Solid-state 13C CP/MAS NMR spectra of 4: (a)
with included dioxane, observation frequency 50.3 MHz,
number of transients 15 184, recycle delay time 5 s, contact
time 5 ms, 0 Hz line broadening, spinning rate 4.0 kHz;
(b) without included dioxane, observation frequency 50.3
MHz, number of transients 18 056, recycle delay time 5 s,
contact time 5 ms, 0 Hz line broadening, spinning rate 3.5
kHz. Asterisks denote spinning sidebands.
F igu r e 4. X-ray powder patterns of 4:dioxane before and
after removal of the included solvent molecule.
To assess the structuring ability of the guest molecule,
clathrates 4:dioxane and 4:CHCl3 were heated at 40-
50 °C under vacuum to remove the included solvent
molecules. The residues were analyzed by solid-state
119Sn and 13C NMR spectroscopy and X-ray powder
diffraction. Figures 2b and 3b show the solid-state
119Sn MAS and 13C CP/MAS NMR spectra of the
4:dioxane inclusion compound after removal of the guest
molecule, and Table 5 summarizes the NMR results.
The solid-state 119Sn NMR spectra of the dried
samples display four resonances with different intensi-
(12) Fyfe, C. A.; Feng, Y.; Grondey, H.; Kokotailo, G. T.; Gies, H.
Chem. Rev. 1991, 91, 1525.
(13) Ripmeester, J . A.; Ratcliffe, C. I. In Comprehensive Supramo-
lecular Chemistry; Lehn, J .-M., Ed.; Pergamon: Oxford, U.K., 1996;
Vol. 8, Chapter 8, pp 323-380.
(14) Zsolnai, L.; Pritzkow, H.; Huttner, G. ZORTEP: Ortep for PC,
Program for Molecular Graphics; University of Heidelberg: Heidelberg,
Germany, 1996.
(15) (a) Bestmann, H. J .; Hadawi, D.; Behl, H.; Bremer, M.; Hampel,
F. Angew. Chem., Int. Ed. Engl. 1993, 32, 1205. (b) J iang, W.; Harwell,
D. E.; Mortimer, M. D.; Knobler, C. B.; Hawthorne, M. F. Inorg. Chem.
1996, 35, 4355.
(16) Carre´, F. H.; Dutremez, S. G.; Gue´rin, C.; Henner, B. J . L.;
Tomberli, V. To be submitted for publication.

1,4-(Triorganostannyl and -silyl)buta-1,3-diynes
Organometallics, Vol. 18, No. 4, 1999 775
Ta ble 6. Cr ysta l Da ta for
P h 3Sn CtCCtCSn P h 3:d ioxa n e,
P h 3Sn CtCCtCSn P h 3, a n d
P h 3SiCtCCtCSi*MeP h Np :d ioxa n e
4:dioxane
4
5:dioxane
formula
mol wt
C
44H38O2Sn2 C40H30Sn2
C43H38O2Si2
642.95
836.12
748.02
cryst color
cryst size, mm
colorless
colorless
colorless
0.50 × 0.30 × 0.40 × 0.30 × 0.4 × 0.4 ×
0.20
cubic
0.30
triclinic
0.2
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
monoclinic
P21 (No. 4)
9.423(2)
8.973(2)
20.728(3)
Pa3h (No. 205) P1h (No. 2)
15.6723(7)
13.5023(19)
22.231(3)
9.5759(15)
91.785(18)
103.526(18)
75.570(18)
2503.0(7)
3
1.488
1110
1.521
180
95.31(1)
3849.4(3)
4
1.443
1672
1.332
293
1745.1(6)
2
1.224
680
0.132
155
Z
d
calcd, g cm-3
F(000)
µ, mm-1
temp of data
collctn, K
F igu r e 6. Arrangement of the diphenyltin moieties around
the dioxane molecule in 4:dioxane.
radiation, graphite- Mo KR
monochromated
Mo KR
Mo KR
2θmax, deg
no. of unique rflns
no. of obsd rflns
50
1135
781 (Fo
48.4
7313
6422 (Fo
50
3044
through the oxygen atoms of the latter molecule. The
guest is located in a cavity formed by 12 phenyl groups
from 6 different molecules of 4. A simplified representa-
tion of this arrangement is shown in Figure 6. The
shortest distances between the guest molecule and the
host are as follows: 3.404 Å for O(dioxane)‚‚‚H(phenyl),
3.319-3.687 Å for C(dioxane)‚‚‚H(phenyl), 2.953-3.594
Å for H(dioxane)‚‚‚C(phenyl), and 2.378-2.798 Å for
H(dioxane)‚‚‚H(phenyl). No diacetylene fragment ap-
pears to delimit the cavity.
>
>
2136 (F >
6.0σ(F))
204
4σ(Fo))
4σ(Fo))
no. of variables
R
Rw
residual electron
dens, e Å-3
goodness of fit, S
76
568
0.0249a
0.0686b
0.18
0.0194a
0.0398b
0.39
0.0575a
0.0629c
0.45
1.070
0.981
0.997
a
b
2
2
2 2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc| )2/∑w|Fo | ]1/2
.
c Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2
.
2
It is clear from these data that the interactions
between the host and the guest are weak, and so it is
not surprising to find that the guest molecule is disor-
dered. Similar observations were made in the case of
the 4:CHCl3 clathrate.9 However, these results are in
sharp contrast with those found for Hart’s complexes,
for which fairly strong CH‚‚‚π interactions between the
host and guest molecules were observed, thus prevent-
ing any disorder of the guest from occurring.5,6 An
analysis of the packing of the (p-biphenyl)Ph2CCtCCt
CCPh2(p-biphenyl):p-xylene inclusion compound reveals
that one hydrogen from a phenyl ring from the host,
H(65), interacts strongly with all of the aromatic carbon
atoms from a nearby p-xylene molecule: the six H(65)‚
‚‚Carom contacts range from 2.923 to 3.366 Å.6 There is
also one short (2.809 Å) H(biphenyl)‚‚‚Carom(p-xylene)
distance. In our case, the dioxane molecule simply fills
the empty spaces that are in the structure.
It may be thought that the cavity in 4:dioxane arises
from strong interactions between phenyl groups from
the host. These interactions do exist, but they do not
appear to be extremely strong: there is only one
intermolecular distance smaller than 2.97 Å, i.e. 2.961
Å between H(4) and C(3), and there are four intermo-
lecular H‚‚‚C contacts between phenyl groups close to
3.1 Å. These interactions are of the edge-to-face type17
with, however, some variations: the interaction between
the H(2)-C(2)-C(3)-H(3) fragment and carbon atoms
from a neighboring phenyl ring is similar to the tilted T
structure reported by J orgensen and Severance.17f The
interaction between H(4) and all of the carbon atoms
F igu r e 5. Packing diagram of 4:dioxane.
1
1
1
molecules at the coordinate /2, /2, /2. By doing so, the
packing around the cell center is made of eight half-
molecules of compound 4. The remaining dioxane mol-
ecules are located in the middle of each edge of the cell
(Figure 5).
The best fit to the diffraction data is achieved when
the dioxane molecule is disordered between three posi-
tions, each of them accounting for one-third occupation.
This model respects the 3-fold rotation axis which passes

776 Organometallics, Vol. 18, No. 4, 1999
Carre´ et al.
single-crystal X-ray diffraction study was conducted on
the material containing no included solvent. Crystals
suitable for the diffraction experiment were grown from
mesitylene. In this case we find that compound 4
crystallizes in the low-symmetry space group P1h with
three molecules per unit cell: one molecule occupies a
general position, and the other one lies on a center of
inversion (Figure 7).
At the molecular level, 4 no longer has the 3h sym-
metry observed in the 4:dioxane inclusion compound:
for both types of molecules present in the cell of 4, it is
found that the tin atoms are not aligned with the four
acetylenic carbons (see the Supporting Information).
The angles formed by three adjacent Csp carbons deviate
slightly from 180°; a more significant deviation is
observed for the SnCtC fragments of the molecule. The
length of the central C-C bond in 4, ca. 1.38 Å, is
shorter than that found in 4:dioxane by about 0.04 Å,
and this seems to compensate for the fact that the Ct
C bonds in the former compound are longer, i.e. about
1.20 Å versus 1.186 Å. No major differences are observed
between the two structures concerning the lengths of
the Sn-C bonds. They all range from 2.11 to 2.13 Å.
As far as the packing of the cell is concerned, we find
that a major change in the organization of the diacety-
lenic molecules has occurred, as compared to that
observed in 4:dioxane, so as to minimize the size of the
voids between the chains. In fact, sizable voids are not
present in the structure, as indicated by the many short
intermolecular carbon‚‚‚carbon distances: there are
eight C(phenyl)‚‚‚C(phenyl) distances between 3.391 and
3.794 Å and three C(acetylenic)‚‚‚C(phenyl) distances
between 3.797 and 3.950 Å.
We also find that there are a great many more
intermolecular contacts between phenyl groups than are
observed in the 4:dioxane structure, and these interac-
tions are stronger. There are 10 distances H(phenyl)‚‚
‚C(phenyl) smaller than 2.97 Å, with the smallest one
being 2.803 Å between H(53) and C(56).
5. Exten sion to Oth er Cla th r a tes. To determine
the main factors controlling the formation and stability
of the clathrates, the structure of the host molecule has
been modified in three different ways: (i) modification
of the end groups, (ii) change in the nature of the
heteroelement, and (iii) modification of the length and
rigidity of the bridge between the bulky end groups.
(i) Hart et al. have shown that the bulkiness of the
end groups in wheel-and-axle-type compounds was
involved in the creation of cavities in which the guest
molecule could nest.5 We have prepared Me3SnCtCCt
CSnMe3, which corresponds to the replacement of all
of the phenyl groups in 4 by methyl groups. This tin
derivative crystallizes easily from acetone, toluene, and
chloroform, but no inclusion of solvent is observed. Most
likely, the cavities are too small to allow the formation
of a clathrate. Steric arguments are obviously important
when trying to rationalize these results. However,
removal of all of the aromatic substituents on tin also
induces a change in the electronic factors of the host
molecule and modifies the packing ability due to the
aromatic groups: CH‚‚‚π interactions are no longer
possible in the case of Me3SnCtCCtCSnMe3.
F igu r e 7. Packing diagram of 4.
from a nearby phenyl ring (the six H(4)‚‚‚Carom distances
range from 2.961 to 3.814 Å) resembles the “T-stacked”
configuration described in Burley’s paper.17d H(5) is in
close contact with only two carbon atoms from a
neighboring phenyl ring (H(5)‚‚‚C(5) ) 3.171 Å and
H(5)‚‚‚C(6) ) 3.092 Å), and the same is true for H(6)
(H(6)‚‚‚C(4) ) 3.747 Å and H(6)‚‚‚C(5) ) 3.248 Å). These
interactions are weaker than those encountered in
4:CHCl3, Ph3PbCtCCtCPbPh3:CH2Cl2 and (p-biphenyl)-
Ph2CCtCCtCCPh2(p-biphenyl):p-xylene.6 In the case
of 4:CHCl3, one phenyl hydrogen, H(4), interacts strongly
in a “T-stacked” fashion with all of the carbon atoms
from a nearby phenyl ring (the six H(4)‚‚‚Carom distances
range from 2.633 to 3.357 Å). A similar edge-to-face
interaction is observed in the case of Ph3PbCtCCt
CPbPh3:CH2Cl2: the six H(3)‚‚‚Carom contacts range
from 2.822 to 3.224 Å. In the case of (p-biphenyl)Ph2-
CCtCCtCCPh2(p-biphenyl):p-xylene, there are two
H(phenyl)‚‚‚C(biphenyl) distances smaller than 2.97 Å,
i.e. H(15)‚‚‚C(32) ) 2.906 Å and H(15)‚‚‚C(33) ) 2.959
Å.
The size of the nearly spherical cavity of 4:dioxane
was calculated from the hydrogen atoms nearest to the
center of the cell. The lower and upper limits for the
diameter are respectively 6.37 and 6.42 Å, and these
values take into account the van der Waals radii of the
hydrogens as defined by Bondi.18
4. Sin gle-Cr ysta l X-r a y Diffr a ction An a lysis of
P h 3Sn CtCCtCSn P h 3 w it h ou t In clu d ed Solven t
Molecu le. To determine the changes brought about to
the solid-state structure of 4 by the solvent molecule, a
(17) (a) Cox, E. G.; Cruickshank, D. W. J .; Smith, J . A. S. Proc. R.
Soc., Ser. A (London) 1958, 247, 1. (b) Burley, S. K.; Petsko, G. A.
Science (Washington, D.C.) 1985, 229, 23. (c) Perutz, M. F.; Fermi, G.;
Abraham, D. J .; Poyart, C.; Bursaux, E. J . Am. Chem. Soc. 1986, 108,
1064. (d) Burley, S. K.; Petsko, G. A. J . Am. Chem. Soc. 1986, 108,
7995. (e) Askew, B.; Ballester, P.; Buhr, C.; J eong, K. S.; J ones, S.;
Parris, K.; Williams, K.; Rebek, J ., J r. J . Am. Chem. Soc. 1989, 111,
1082. (f) J orgensen, W. L.; Severance, D. L. J . Am. Chem. Soc. 1990,
112, 4768. (g) Hunter, C. A.; Sanders, J . K. M. J . Am. Chem. Soc. 1990,
112, 5525. (h) Hunter, C. A. Chem. Soc. Rev. 1994, 101. (i) Dougherty,
D. A. In Comprehensive Supramolecular Chemistry; Lehn, J .-M., Ed.;
Pergamon: Oxford, U.K., 1996; Vol. 2; Chapter 6, pp 195-209. (j)
Weiss, H.-C.; Bla¨ser, D.; Boese, R.; Doughan, B. M.; Haley, M. M. Chem.
Commun. 1997, 1703.
(ii) The SnPh3 groups of Ph3SnCtCCtCSnPh3 (4)
(18) Bondi, A. J . Phys. Chem. 1964, 68, 441.
have been replaced by SiPh3 and PPh2 moieties. The

1,4-(Triorganostannyl and -silyl)buta-1,3-diynes
Organometallics, Vol. 18, No. 4, 1999 777
heteroelement is expected to modify the ability of the
molecule to form host-guest complexes by its size and
coordination number. 1,4-Bis(diphenylphosphino)buta-
1,3-diyne crystallizes from acetone, toluene, and chlo-
roform, but no inclusion of solvent is observed. This
result can be explained by the coordination number of
3 for phosphorus instead of 4 for tin, which must
diminish the potential formation of cavities large enough
to accommodate solvent molecules in the crystalline
state. In agreement with this, Ph2P(Se)(CH2)2(Se)PPh2
is known to be a host toward various aromatic sol-
vents.19 Nonetheless, electronic effects due to the pres-
ence of a lone pair on phosphorus in Ph2PCtCCtCPPh2
cannot be completely ruled out.
Ph3Sn(CH2)4SnPh3 was allowed to crystallize from
chloroform, dioxane, THF, toluene, chlorobenzene, and
pyridine; inclusion of solvent in the crystal was observed
only in the case of dioxane. The stoichiometry of the
1
inclusion compound is 1:1, as determined by H NMR
spectroscopy and TGA measurements. Thus, clathrate
formation occurs only with the solvent giving the most
stable complex with 4. Furthermore, the temperature
range for the weight loss (between 40 and 90 °C) shows
that the clathrate Ph3Sn(CH2)4SnPh3:dioxane is less
stable than the clathrate with the rigid diacetylene
spacer 4:dioxane (see Table 1).
In summary, the results described above show that
one triple bond is not sufficiently long to allow the
formation of cavities capable of including guest mol-
ecules. With a spacer of four carbons, the main factor
controlling the formation of host-guest complexes
seems to be the bulkiness of the end groups: inclusion
complexes are obtained when the tin atom possesses
phenyl substituents and not when methyl groups are
present. However, the replacement of the phenyl groups
by methyl substituents modifies the Lewis acidity of the
tin atom and also prevents CH‚‚‚π interactions from
occurring, and these phenomena most likely contribute
to the fact that clathrates do not form when SnMe3
fragments are present. The crystal structure of 4:diox-
ane shows that the guest molecule is surrounded only
by phenyl groups; no interaction between the solvent
molecule and the diacetylene unit is observed, nor is
one observed between the solvent molecule and the tin
atoms. This latter result suggests that the tin atoms in
4 are not sufficiently Lewis acidic to interact with the
solvent molecule. Such interactions are known to occur
in compounds where the tin atom is bonded to electron-
withdrawing groups.22 Finally, it should be emphasized
that the rigidity of the C4 bridge is also important, since
4 forms inclusion complexes with a large variety of
solvents; only one such complex was obtained with Ph3-
Sn(CH2)4SnPh3.
6. Solid -Sta te NMR a n d X-r a y Cr ysta llogr a p h ic
Stu d ies of P h 3SiCtCCtCSi*MeP h Np (5):d ioxa n e.
The complex 5:dioxane has been characterized by solid-
state 13C and 29Si NMR spectroscopy and X-ray crystal-
lography. In the room-temperature 13C NMR spectrum,
the acetylenic carbons of the clathrate appear as four
lines at 82.9, 86.2, 92.0, and 92.7 ppm, as expected for
four magnetically different carbon atoms. The carbon
signal of the guest is observed at 66.5 ppm. It is worth
pointing out that more than one resonance might have
been expected for the methylene carbons of the dioxane
molecule, as they are crystallographically nonequivalent
and, furthermore, diastereotopic. The fact that only one
signal is observed may be purely accidental. Another
possibility is that the higher thermal motion of the
dioxane molecule at room temperature renders the
methylene carbons magnetically equivalent. If this
hypothesis is correct, it means that, even though there
are some strong interactions between the host and the
guest at low temperature, preventing the guest from
being disordered (vide infra), these interactions are
overpowered at room temperature by thermal motion.
The fact that the 13C resonance of the dioxane molecule
When the tin atoms of compound 4 are replaced by
silicon atoms, namely in the case of Ph3SiCtCCt
CSiPh3, no inclusion complex forms upon crystallization
from the same solvents as those used in the case of 4,
e.g. THF, dioxane, chloroform, dichloromethane, tolu-
1
ene, p-xylene, and pyridine, as determined by H NMR
spectroscopy. This result is somewhat unexpected, as
Ph3CCtCCtCCPh3 is known to give a 1:1 inclusion
compound with chloroform.5 The difference that exists
between Ph3SiCtCCtCSiPh3 and Ph3SnCtCCtCSnPh3
can easily be rationalized on the basis of the fact that
silicon and tin have very different atomic radii, i.e. 1.17
Å for silicon and 1.40 Å for tin.20 However, effects due
to the size of the heteroelement cannot account for the
difference that exists between Ph3SiCtCCtCSiPh3 and
Ph3CCtCCtCCPh3, as carbon has a much smaller
atomic radius than silicon.20 This difference is believed
to arise from electronic effects, due to the fact that
carbon has a much higher Pauling electronegativity
than silicon: i.e. 2.5 for carbon and 1.8 for silicon.20
Nonetheless, electronic effects can be overpowered by
crystal packing forces; this is suggested by the observa-
tion that a 1:1 inclusion complex forms between Ph3-
SiCtCCtCSi*MePhNp (5) and dioxane. The X-ray
crystal structure of this clathrate indicates that the
guest molecule sits in channels formed by Ph3Si groups
from the host (vide infra).
(iii) The role of the bridging carbon chain was studied
by changing its length and rigidity. The formation of
inclusion compounds was tested with Ph3SnCtCSnPh3.
This derivative only has one triple bond instead of two
in 4. Ph3SnCtCSnPh3 crystallizes from chloroform,
dioxane, THF, toluene, pyridine, chlorobenzene, and
trichloroethylene without the inclusion of a solvent
molecule. Solvent-metal interactions appear to be
absent in solution, as evidenced by the closeness be-
tween the solid-state and solution 119Sn NMR data. The
chemical shifts of the resonances observed in the 119Sn
CP/MAS NMR spectrum of Ph3SnCtCSnPh3 are -184.6
and -198.3 ppm. The values found in solution are as
follows: -176.1 ppm (CDCl3),21 -174.0 ppm (toluene),
-177.1 ppm (pyridine), and -179.6 ppm (dioxane).
To change the flexibility of the carbon chain, without
changing drastically the distance between the two bulky
triphenyltin groups, we have replaced the 1,3-butadiyne-
1,4-diyl spacer by the saturated 1,4-butanediyl group.
(19) Brown, D. H.; Cross, R. J .; Mallinson, P. R.; MacNicol, D. D. J .
Chem. Soc., Perkin Trans. 2 1980, 993.
(20) Greenwood, N. N.; Earnshaw, A. Chemistry of the Elements;
Pergamon: Oxford, U.K., 1984; p 431.
(21) Wrackmeyer, B. Annu. Rep. NMR Spectrosc. 1985, 16, 73.
(22) Smith, P. J .; Tupcˇiauskas, A. P. Annu. Rep. NMR Spectrosc.
1978, 8, 291.

778 Organometallics, Vol. 18, No. 4, 1999
Carre´ et al.
Ta ble 7. Sh or test Host-Gu est Con ta cts in th e
Ca se of 5:d ioxa n e
atomsa
dist (Å)b
atomsa
dist (Å)b
H(51a)‚‚‚C(45)
H(51a)‚‚‚C(46)
H(51b)‚‚‚C(26)
H(51b)‚‚‚H(36)
H(53a)‚‚‚H(24)
2.77(1)
2.93(1)
2.95(1)
2.36(1)
2.35(1)
H(54b)‚‚‚C(32)
H(54b)‚‚‚C(46)
O(1)‚‚‚H(23)
O(2)‚‚‚H(35)
O(2)‚‚‚H(36)
2.65(1)
2.91(1)
2.42(1)
2.57(1)
2.67(1)
a
Ha and Hb are located on the same carbon atom of the dioxane
b
molecule. van der Waals contacts: 2.97 Å between hydrogen and
an aromatic carbon, 2.40 Å between two hydrogens, and 2.72 Å
between hydrogen and oxygen.18
another, but there are two short intermolecular contacts
between the H(5) hydrogen of a naphthyl group and the
C(33) and C(34) carbons from a neighboring Ph3Si
moiety: the H(5)‚‚‚C(33) and H(5)‚‚‚C(34) distances are
respectively 2.956 and 2.856 Å. A fairly short distance
(2.776 Å) is also observed between the H(14) hydrogen
of the phenyl group bound to the stereogenic silicon
center and the C(43) carbon from a nearby Ph3Si
fragment.
Finally, a comparison between the structure of Ph3-
SnCtCCtCSnPh3:dioxane and that of Ph3SiCtCCt
CSi*MePhNp:dioxane allows for the following comment
to be made: in the tin derivative, the dioxane molecule
is confined in cavities formed by phenyl groups (it is a
true clathrate), whereas in the case of Ph3SiCtCCt
CSi*MePhNp:dioxane, the guest molecule lies in zigzag-
shaped channels built by phenyl substituents from the
Ph3Si groups. The cavities in these channels roughly
resemble compressed spheres: a spacing of about 4.2 Å
is found along the direction going through the oxygen
atoms of the dioxane molecule, and it is 6.2 and 7.0 Å
in directions perpendicular to that axis. These values
take into account the van der Waals radii of the atoms
delimiting the cavity.18
F igu r e 8. View along the b axis of the cell of 5:dioxane
showing the dioxane molecule surrounded by the SiPh3
groups of Ph3SiCtCCtCSi*MePhNp.
is broad and the fact that the host-guest complex easily
loses its guest at room temperature (see below) appear
to agree with this interpretation. The solid-state 29Si
NMR spectrum displays two sharp lines with chemical
shifts close to those found in solution (-24.8 and -28.5
ppm).
When crystalline 5:dioxane is left in air at room
temperature, it loses the dioxane molecule, as confirmed
by the disappearance of the 13C resonance at 66.5 ppm.
The solid-state NMR spectra of the unsolvated sample
display more lines than are observed for the solvated
material (vide supra): the 29Si NMR spectrum shows a
main signal at -25.6 ppm (relative intensity 1) along
with four smaller signals at δ -28.5, -29.7, -30.2, and
-30.7 ppm (each signal with a relative intensity of 0.2).
The acetylenic carbons give rise to nine signals in the
range 83-93 ppm in the solid-state 13C NMR spectrum,
confirming the loss of crystallinity of the material.
Crystal data for the 5:dioxane complex are listed in
Table 6. The crystal system is monoclinic, and the space
group is P21. Full lists of bond lengths and angles and
a ZORTEP drawing of the Ph3SiCtCCtCSi*MePhNp
part of the clathrate are given in the Supporting
Information. Figure 8 shows the crystal packing of the
unit cell. The cell contains two molecules of Ph3SiCt
CCtCSi*MePhNp and two molecules of dioxane.
The lengths of the triple bonds and the single bond
of the butadiynyl unit (respectively 1.219(9), 1.195(10),
and 1.375(9) Å) are close to the values observed for other
diacetylenic compounds.9,15,16 The four acetylenic car-
bons and the two silicon atoms are nearly aligned with
bond angles ranging from 176.2 to 178.7°.
Con clu sion
The work presented here shows that Ph3SnCtCCt
CSnPh3 (4) forms 1:1 inclusion compounds with a wide
range of organic molecules. The stability of these
clathrates has been determined by TGA measurements
and guest selectivity studies. The first important struc-
tural feature that the host must possess in order to form
stable host-guest compounds is the presence of bulky
Ph3M (M ) C, Si, Sn) groups. This is supported by the
fact that, in the crystal structures of 4:dioxane and Ph3-
SiCtCCtCSi*MePhNp (5):dioxane, the dioxane mol-
ecule is located in the vicinity of the Ph3M groups. No
clathrate is obtained when the end group is Ph2P.
4:dioxane has a true clathrate (cage) structure, whereas
that of 5:dioxane is of the channel type. The second
requirement for the host is to have a chain with at least
four carbon atoms between the two end groups. Stable
complexes are obtained when the carbon chain between
the bulky groups is rigid, and less stable ones are
obtained when the carbon chain is flexible. A combina-
tion of multinuclear solid-state NMR and X-ray powder
diffraction analyses performed on 4:dioxane and 5:di-
oxane shows that the presence of the solvent molecule
is essential in that it maintains the cohesion of the
crystal lattice; its removal disorganizes the structure
of the host in the solid. It is possible to prepare single
crystals of 4 with no included solvent. In this case, it is
The refinement of the structure allowed the determi-
nation of the absolute configuration at silicon: it is R
(see Experimental Section).
There are some sizable van der Waals interactions
between the dioxane molecule and the triphenylsilyl
groups from surrounding hosts, and most likely this is
the reason the guest molecule is not disordered. Table
7 gives the shortest distances between the phenyl
groups of the Ph3Si moiety and the dioxane molecule.
There is no interaction between the guest and the
methylphenylnaphthylsilyl part of the host, nor is there
one between the former and the diacetylene unit. Two
adjacent naphthyl groups do not interact with one

1,4-(Triorganostannyl and -silyl)buta-1,3-diynes
Organometallics, Vol. 18, No. 4, 1999 779
Hz, C3,5), 129.4 (4J (13C,117/119Sn) ) 11 Hz, C4), 137.6 (2J (13C,-
119Sn) ) 36 Hz, 2J (13C,117Sn) ) 34 Hz, C2,6), 139.6 (1J (13C,-
found that a change in the organization of the diacety-
lenic molecule in the solid state has occurred, as
compared to that observed in 4:dioxane, so as to
minimize the size of the voids between the chains.
1
119Sn) ) 483 Hz, J (13C,117Sn) ) 461 Hz, Cipso).
(S)-(-)-MeP h Np SiCl. (S)-(-)-Chloromethylphenylnaphth-
ylsilane is prepared from phenyltrichlorosilane by following a
five-step procedure.
(i) Phenyltrimethoxysilane is obtained from the reaction
between phenyltrichlorosilane and methanol in the presence
of triethylamine.30
(ii) Dimethoxyphenylnaphthylsilane results from the reac-
tion between phenyltrimethoxysilane and naphthylmagnesium
bromide.30
(iii) The reduction of dimethoxyphenylnaphthylsilane with
lithium aluminum hydride gives phenylnaphthylsilane, as
described below.
(iv) Phenylnaphthylsilane is allowed to react first with
(1R,2S)-(-)-ephedrine in the presence of Wilkinson’s catalyst,
ClRh(PPh3)3, and then with methylmagnesium bromide to
produce (R)-(+)-methylphenylnaphthylsilane according to a
reported method.31
(v) In the last step, (S)-(-)-chloromethylphenylnaphthylsi-
lane is obtained via chlorination of (R)-(+)-methylphenylnaph-
thylsilane with chlorine gas, in CCl4, at 0 °C.32
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All of the reactions were carried
out under nitrogen or argon using standard Schlenk-line
techniques. Solvents were dried and distilled prior to use.
Tetrahydrofuran (THF) was distilled over sodium-benzophe-
none ketyl. The solvents used as guests were utilized without
purification.
1H NMR spectra were obtained on Bruker AW 80, AC 250,
and Avance DPX 200 spectrometers and 13C, 29Si, and 119Sn
NMR spectra on Bruker WP 200 SY and AC 250 instruments.
Solid-state 13C, 119Sn, and 29Si magic-angle spinning (MAS) and
cross-polarization magic-angle spinning (CP/MAS) NMR spec-
tra were recorded on Bruker ASX 200 and ASX 400 spectrom-
eters using 4 or 7 mm zirconia rotors. Spinning rates ranged
from 3.5 to 12 kHz. The chemical shifts, δ, are relative to
tetramethylsilane (TMS) for 1H, 13C, and 29Si and tetrameth-
ylstannane for 119Sn. Mass spectra were recorded on a J EOL
J MS-DX300 spectrometer. Thermogravimetric analyses (TGA)
were carried out under flowing argon (50 mL/min) with a
NETZSCH STA 409 thermobalance and a heating rate of 5
°C/min. DSC experiments were carried out under nitrogen on
a Mettler 30 instrument with a heating rate of 5 °C/min. X-ray
powder patterns were obtained using Cu KR radiation on a
P h Np SiH2. A solution of PhNpSi(OMe)2 (93 g, 0.32 mol) in
diethyl ether (500 mL) is added dropwise to a suspension of
LiAlH4 (12 g, 0.32 mol) in diethyl ether (500 mL). The mixture
is stirred at room temperature for 16 h and then refluxed for
30 min. It is hydrolyzed with a chilled dilute solution of HCl
and extracted with diethyl ether. The organic layer is dried
over MgSO4. The volatiles are removed using a rotary evapo-
rator. The residual oil is distilled under reduced pressure.
PhNpSiH2 is obtained as a yellow liquid with a 91% yield (67
Philips diffractometer interfaced with
a multiacquisition
computerized system developed by Prof. R. Fourcade (Univer-
site´ Montpellier II).23
1
g, 0.29 mol). Bp0.01: 110-115 °C. H NMR (CCl4; δ, ppm): 5.4
Ma ter ia ls. Chlorosilanes, chlorostannanes, diphenylchlo-
rophosphane, organolithium derivatives, and 1,4-dibromobu-
tane were purchased from Aldrich, Fluka, and J anssen. The
following compounds were prepared according to published
methods: Me3SiCtCCtCSiMe3,24 LiCtCCtCLi,25,26 Ph3SiCt
CCtCSiPh3,25 Ph2PCtCCtCPPh2,27 Ph3SnCtCSnPh3,28 and
Ph3SnCtCCtCSnPh3.25
(s, 2H, SiH2), 7.6-8.2 (m, 12H, aromatics). IR (neat): 2139 vs
(Si-H) cm-1
.
(R)-(+)-P h 3SiCtCCtCSiMeP h Np (5). A 2.20 M solution
of n-BuLi (4.94 mL, 10.86 mmol) is added dropwise to a cold
(-78 °C) solution of Ph3SiCtCCtCH33 (3.35 g, 10.86 mmol)
in diethyl ether (60 mL). After it is stirred for 15 min at -78
°C, the mixture containing LiCtCCtCSiPh3 turns into a red
suspension. At -78 °C, a solution of (S)-(-)-MePhNpSiCl (3.43
g, 12.14 mmol; [R]D ) -5.37° (pentane)) in diethyl ether (40
mL) is added to the suspension. The mixture is stirred for 12
h, during which time it is warmed to room temperature. After
hydrolysis with a saturated solution of NH4Cl and extraction
with diethyl ether, the organic layer is dried over MgSO4. The
volatiles are removed under reduced pressure. The solid
residue is dissolved in a CH2Cl2-hexane mixture (40:60 v/v)
and the solution cooled at -18 °C. (R)-(+)-Ph3SiCtCCt
CSiMePhNp (5) is obtained as a white powder in 82% yield
(4.97 g, 8.96 mmol). Mp: 169.1-170.4 °C. [R]D ) +10.9° (CH2-
Cl2). 1H NMR (CCl4; δ, ppm): 0.9 (s, 3H, CH3), 7.3-8.0 (m,
27H, aromatics). 13C NMR (CDCl3; δ, ppm): -0.8 (s, CH3), 82.5
(s, Ph3SiCtC), 84.5 (s, CtCSiMePhNp), 91.9 (s, CtCSiMe-
PhNp), 92.5 (s, Ph3SiCtC), 125.6-136.3 (17 signals, aromat-
ics). 29Si NMR (CDCl3; δ, ppm): -24.4 (s, SiMePhNp), -28.3
(s, SiPh3). IR (CCl4): 3071 m, 3054 m (C-H arom), 2961 w
(C-H aliph), 2069 vs (CtC), 1590 w, 1429 vs (aromatics), 1255
Syn t h eses. Me3Sn CtCCtCSn Me3. Me3SnCtCCtCSn-
Me328 is a known compound that is more conveniently prepared
1
by the procedure described by Corriu et al.25 Yield: 78%. H
NMR (CDCl3; δ, ppm): 0.2 (s, 2J (1H,119Sn) ) 61 Hz, 2J (1H,
117Sn) ) 58 Hz). 13C NMR (CDCl3; δ, ppm): -7.3 (1J (13C,119Sn)
) 407 Hz, 1J (13C,117Sn) ) 389 Hz, Sn(CH3)3), 85.0 (1J (13C,
119Sn) ) 369 Hz, 1J (13C,117Sn) ) 353 Hz, SnCt), 91.9
(2J (13C,117/119Sn) ) 81 Hz, 3J (13C,117/119Sn) ) 18 Hz, SnCtC).
119Sn NMR (CDCl3; δ, ppm): -59.0. MS (EI): m/z (assignment,
relative intensity) 361 ([M - CH3]+, 100).
P h 3Sn (CH2)4Sn P h 3. Ph3Sn(CH2)4SnPh3 was prepared ac-
cording to the method reported by Holtkamp et al.29 Yield:
45%. Mp: 155.5-156.2 °C. 1H NMR (CDCl3; δ, ppm): 1.7 and
2.1 (two multiplets, 8H, CH2), 7.5-7.7 (multiple signals, 30H,
aromatics). 13C NMR (CDCl3; δ, ppm): 11.2 (1J (13C,119Sn) )
1
393 Hz, J (13C,117Sn) ) 375 Hz, SnCH2), 31.9 (2J (13C,119Sn) )
66 Hz, 2J (13C,117Sn) ) 64 Hz, 3J (13C,117/119Sn) ) 21 Hz,
SnCH2CH2), 129.1 (3J (13C,119Sn) ) 49 Hz, 3J (13C,117Sn) ) 47
w (Si-Csp ), 1113 vs (Si-Csp ) cm-1. MS (EI, 70 eV): m/z
(assignment, relative intensity) 555 (M+, 57), 539 ([M - Me -
H]+, 39), 476 ([M - Ph - 2H]+, 56), 461 ([M - Ph - Me -
3
2
(23) Fourcade, R.; Ducourant, B.; Mascherpa, G. CNRS-ANVAR
license 5706-00, 1988.
(24) (a) Zweifel, G.; Rajagopalan, S. J . Am. Chem. Soc. 1985, 107,
700. (b) Hartmann, H.; Wagner, H.; Karbstein, B.; El A'ssar, M. K.;
Reiss, W. Naturwissenschaften 1964, 51, 215.
(25) Bre´fort, J .-L.; Corriu, R. J . P.; Gerbier, Ph.; Gue´rin, C.; Henner,
B. J . L.; J ean, A.; Kuhlmann, Th.; Garnier, F.; Yassar, A. Organome-
tallics 1992, 11, 2500.
(26) Ijadi-Maghsoodi, S.; Barton, T. J . Macromolecules 1990, 23,
4485.
(27) Corriu, R. J . P.; Gue´rin, C.; Henner, B. J . L.; J olivet, A. J .
Organomet. Chem. 1997, 530, 39.
(30) Corriu, R. J . P.; Lanneau, G. F.; Royo, G. L. J . Organomet.
Chem. 1972, 35, 35.
(31) (a) Corriu, R. J . P.; Moreau, J . J . E. Bull. Soc. Chim. Fr. 1975,
901. (b) Corriu, R. J . P.; Henner, B. J . L. J . Organomet. Chem. 1976,
105, 303.
(32) Sommer, L. H.; Frye, C. L.; Parker, G. A.; Michael, K. W. J .
Am. Chem. Soc. 1964, 86, 3271.
(33) Ph3SiCtCCtCH was prepared by following the same procedure
as that reported in the literature for other triorganosilylbuta-1,3-
diynes. See: Stracker, E. C.; Zweifel, G. Tetrahedron Lett. 1990, 31,
6815.
(28) Le Quan, M.; Cadiot, P. Bull. Soc. Chim. Fr. 1965, 35.
(29) Holtkamp, H. C.; Blomberg, C.; Bickelhaupt, F. J . Organomet.
Chem. 1969, 19, 279.

780 Organometallics, Vol. 18, No. 4, 1999
Carre´ et al.
2H]+, 23), 398 ([M - 2Ph - 3H]+, 9), 333 ([M - Np - Ph -
Me - 3H]+, 39), 283 ([Ph3SiCtC]+, 34), 259 (Ph3Si+, 54), 247
(MePhNpSi+, 30), 231 ([PhNpSi - H]+, 56), 181 ([Ph2Si - H]+,
79), 155 (NpSi+, 31), 105 (PhSi+, 89), 77 (Ph+, 14). Anal. Calcd
for C39H30Si2: C, 84.45; H, 5.45; Si, 10.12. Found: C, 84.3; H,
5.2; Si, 10.0.
Sommer34 and Corriu35 have reported that nucleophilic
attack of (phenylethynyl)lithium on (S)-(-)-alkylchloronaph-
thylphenylsilanes takes place with inversion of configuration
at silicon and is stereospecific. On the basis of these results,
it can be anticipated that the attack of LiCtCCtCSiPh3 on
(S)-(-)-MePhNpSiCl will lead to a silane (5) in which the
absolute configuration of the silicon center is R. This is
confirmed by a single-crystal X-ray diffraction analysis of the
5:dioxane inclusion compound (vide infra). An analysis of a
bulk sample of 5 using a chiral HPLC column (the column used
was a CHIRALPAK AD, the eluent an hexane-2-propanol
mixture (99:1 v/v), and the flow rate 1 mL/min) confirms that
the reaction is stereospecific, as an enantiomeric excess greater
than 99.9% is calculated from the chromatogram.
from the literature.40 All of the reflections (3385) were taken
into account in the refinement on Fo2. The last cycle of
refinement gave R(obs) ) 0.0249 and Rw(obs) ) 0.0686 with
76 variable parameters and a maximum residual peak of 0.18
e Å-3. The labeling scheme of the host part of the 4:dioxane
clathrate is shown in the Supporting Information, and bond
lengths and angles are listed.
Cr ysta l Str u ctu r e of 4 w ith ou t In clu d ed Solven t
Molecu le. Sa m p le P r ep a r a tion . Suitable crystals were
grown from a concentrated solution of 4 in mesitylene at room
temperature. A small colorless block of dimensions 0.40 × 0.30
× 0.30 mm was glued on a glass fiber that was subsequently
mounted on a IPDS-Stoe diffractometer equipped with an
Oxford Cryostream cooling device.
Da ta Collection . Data were collected at 180 K with
graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å).
A total of 19 635 reflections were measured in φ movement
rotation from 0 to 249.6°.41 The cell parameters (Table 6) were
refined from 5000 reflections. Two hundred control reflections
were measured; neither decay nor absorption corrections were
made to the data. The absence of systematic absences indicated
the triclinic space group P1 or P1h. The merge program in P1h
gave 7313 unique reflections (Rint ) 0.0215).41 Of these
reflections, 6422 were considered to be observed (Fo > 4σ(Fo)).
The calculated Z value is 3.
P r ep a r a tion of th e Cla th r a tes. Between 50 and 100 mg
of host was dissolved in a minimum amount of boiling solvent
(typically 2-5 mL), and the solution was allowed to crystallize
at room temperature or at -20 °C. Crystals were quickly dried
and crushed just before carrying out TGA and NMR measure-
ments. Elemental analyses of two of the most stable 4:solvent
clathrates gave the following results. Anal. Calcd for 4:dioxane,
Str u ctu r e Deter m in a tion a n d Refin em en t. The Patter-
son method using SHELXS-9738 succeeded in locating the Sn
atoms. The SHELXL-97 program39 was used for the full-matrix
C
44H38O2Sn2: C, 63.20; H, 4.58; O, 3.83. Found: C, 63.08; H,
2
least-squares refinement against Fo with all non-hydrogen
4.59; O, 3.68. Calcd for 4:CHCl3, C41H31Cl3Sn2: C, 56.77; H,
3.60; Cl, 12.26. Found: C, 56.76; H, 3.35; Cl, 13.23.
atoms anisotropic. Hydrogen atoms were introduced in the
calculations with the riding model with Uiso values equal to
1.1 times that of the atom of attachment. The atomic scattering
factors for all atoms were taken from the literature.40 All of
the reflections (7313) were taken into account in the refine-
ment on Fo2. The last cycle of refinement gave R(obs) ) 0.0194
and Rw(obs) ) 0.0398 with 568 variable parameters and a
maximum residual peak of 0.39 e Å-3. ZORTEP drawings of
the one and a half independent molecules of 4 present in the
unit cell along with the corresponding labeling schemes may
be found in the Supporting Information. Tables of bond lengths
and angles are also given.
Cr ysta l Str u ctu r e of 5:d ioxa n e. Sa m p le P r ep a r a tion .
Crystals of the 5:dioxane clathrate were grown from a dioxane
solution at room temperature. A small plate of dimensions 0.40
× 0.40 × 0.20 mm was stuck on a glass fiber with mineral oil
and immersed in a stream of cold nitrogen on an Enraf-Nonius
CAD4 automated diffractometer.
Da ta Collection . Two sets of data were collected. The first
set was collected at 155 K with graphite-monochromated Mo
KR radiation (λ ) 0.710 69 Å). Lattice constants (Table 6)
result from the least-squares refinement of 25 reflections
measured in the range 15.3 < 2θ < 46.6°. The intensities of
three standard reflections were monitored at intervals of 60
min; no significant change in these intensities was observed.
The systematic absence (0k0, k ) 2n + 1) is in agreement with
space groups P21 and P21/m. The structure factor amplitudes
were obtained after the usual Lorentz and polarization cor-
rections (Rint ) 0.0287). Only the reflections with F > 6.0σ(F)
were considered to be observed. No absorption correction was
made.
This set of data proved to be of good quality to solve the
structure and led to a conventional R value of 0.0575. However,
only nonsignificant differences were observed in the R and Rw
values upon changing the configuration of the silicon atom.
For a reliable determination of the absolute configuration,
another set of data was collected at 158 K on a smaller crystal
using Cu KR radiation (λ ) 1.5418 Å) (see below).
Cr ysta l Str u ctu r e of 4:d ioxa n e. Sa m p le P r ep a r a tion .
X-ray-quality crystals were grown from a concentrated solution
of 4 in dioxane at room temperature. A small colorless block
of dimensions 0.50 × 0.30 × 0.20 mm was glued on a glass
fiber that was subsequently mounted on an Enraf-Nonius
CAD4 automated diffractometer.
Da ta Collection . Data were collected at 293 K with
graphite-monochromated Mo KR radiation (λ ) 0.710 73 Å).
The lattice parameters (Table 6) were determined from a least-
squares fit to 25 reflections measured in the range 26.0 < 2θ
< 37.0°. The intensities of three standard reflections were
monitored at intervals of 120 min; no significant change in
these intensities occurred during data collection. The system-
atic absences (0kl, k ) 2n + 1; h0l, l ) 2n + 1; hk0, h ) 2n +
1) indicated the cubic space group Pa3h. The calculated Z value
is 4. Reduction to Fo2 and σ(Fo2) and corrections for background
and Lorentz and polarization were performed in the usual
manner,36 and absorption corrections were made from ψ
scans.37 A total of 3385 reflections were collected, of which 1135
were unique (Rint ) 0.0218); 781 were considered to be
observed (Fo > 4σ(Fo)).
Str u ctu r e Deter m in a tion a n d Refin em en t. The Patter-
son method using SHELXS-9738 succeeded in locating the Sn
atom. The SHELXL-97 program39 was used for the full-matrix
2
least-squares refinement against Fo with all non-hydrogen
atoms anisotropic. Phenyl hydrogens were introduced in the
calculations with the riding model with Uiso equal to 1.1 times
that of the atom of attachment. Hydrogen atoms of the
disordered dioxane molecule were not included in the calcula-
tions. The atomic scattering factors for all atoms were taken
(34) Sommer, L. H.; Korte, W. D. J . Am. Chem. Soc. 1967, 89, 5802.
(35) (a) Corriu, R.; Royo, G. Bull. Soc. Chim. Fr. 1972, 1490. (b)
Corriu, R.; Royo, G. Bull. Soc. Chim. Fr. 1972, 1497.
(36) Fair, C. K., MolEN. Structure Solution Procedures; Enraf-
Nonius, Delft, The Netherlands, 1990.
(37) North, A. C. T.; Phillips, D. C.; Mathews, F. S. Acta Crystallogr.
1968, A24, 351.
(38) Sheldrick, G. M. SHELXS-97: Program for Crystal Structure
Solution; University of Go¨ttingen: Go¨ttingen, Germany, 1990.
(39) Sheldrick, G. M. SHELXL-97: Program for the Refinement of
Crystal Structures from Diffraction Data; University of Go¨ttingen:
Go¨ttingen, Germany, 1997.
(40) International Tables for Crystallography; Kluwer Academic:
Dordrecht, The Netherlands, 1992; Vol. C.
(41) Stoe IPDS Manual: Version 2.87; Stoe & Cie: Darmstadt,
Germany, 1997.

1,4-(Triorganostannyl and -silyl)buta-1,3-diynes
Organometallics, Vol. 18, No. 4, 1999 781
Str u ctu r e Deter m in a tion a n d Refin em en t. The non-
centrosymmetric space group P21 was assumed in view of the
chirality of compound 5. Direct methods (SHELXS-86 pro-
gram42) succeeded in locating all of the non-hydrogen atoms,
except those of the dioxane molecule. These atoms were located
in a subsequent difference Fourier map. The silicon atoms were
refined anisotropically. The positions of the hydrogen atoms
were calculated (SHELX-76 program43) and taken into account
in the refinement on Fo. The atomic scattering factors for all
atoms were taken from the literature.44 The refinement based
on the data obtained with Mo KR radiation converged to R
and Rw values of 0.0575 and 0.0629, respectively. The labeling
scheme of the host part of the 5:dioxane inclusion compound
along with full lists of bond lengths and angles may be found
in the Supporting Information.
(1347 observed reflections) measured with the Cu KR radia-
tion. The displayed absolute configuration (R) (see the Sup-
porting Information) gave the final residuals R ) 0.0798 and
Rw ) 0.0850, whereas the opposite configuration led to R )
0.0803 and Rw ) 0.0857. Calculation of the R index45 for the
0.01 level gives 1.0036.
Ack n ow led gm en t. We wish to thank Prof. R. J . P.
Corriu for fruitful discussions and the CNRS and
Ministry of National Education for financial support.
Chiral Technologies Europe (Illkirch, France) is also
gratefully acknowledged for carrying out the HPLC
determination of the enantiomeric purity of 5.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and experimental details, positional and thermal param-
eters, and all interatomic distances, bond angles, and final
hydrogen coordinates and ZORTEP drawings for 4, 4:dioxane,
and 5:dioxane (31 pages). Ordering information is given on
any current masthead page.
Two distinct refinements were conducted in identical ways
for each possible configuration at silicon using the data set
(42) Sheldrick, G. M. SHELXS-86: A Program for Crystal Structure
Solution; Institut fu¨r Anorganische Chemie der Universita¨t: Go¨ttingen,
Germany, 1986.
(43) Sheldrick, G. M. SHELX-76: A Program for Crystal Structure
Determination; University of Cambridge: Cambridge, England, 1976.
(44) Cromer, D. T.; Mann, J . B. Acta Crystallogr. 1968, A24, 321.
OM9804430
(45) Hamilton, W. C. Acta Crystallogr. 1965, 18, 502.