Solventless Reactions for the Synthesis of Organotin Clusters and Cages

Article abstract of DOI:10.1021/om030338c

Organotin clusters and cages have been synthesized in quantitative yields by using a benign solventless synthetic methodology. Using this method a variety of structural forms, which include the drum, O-capped cluster, tetranuclear oxo cage, discrete, and polymeric compounds, have been synthesized. All these compounds (1-11) have been characterized by spectroscopic and analytical techniques. The new compounds, which include the hexameric drum [n-BuSn(O)OCOAd]₆ (Ad = adamantyl) 9, a triorganotin-based discrete structure Ph₃SnO₂C-C₆-H ₂2,4,6-Me₃ (10), and a polymer Ph₃SnOSO ₂-C₆H₃-2,5-Me₂ (11), have been characterized by single-crystal X-ray crystallography.

Full text of DOI:10.1021/om030338c

3710
Organometallics 2003, 22, 3710-3716
Solven tless Rea ction s for th e Syn th esis of Or ga n otin
Clu ster s a n d Ca ges§
Vadapalli Chandrasekhar,*,† Viswanathan Baskar,†
Ramamoorthy Boomishankar,† Kandasamy Gopal,† Stefano Zacchini,‡
J amie F. Bickley,‡ and Alexander Steiner‡
Department of Chemistry, Indian Institute of Technology, Kanpur-208 016, India, and
Department of Chemistry, University of Liverpool, Liverpool-L69 7ZD, U.K.
Received May 7, 2003
Organotin clusters and cages have been synthesized in quantitative yields by using a benign
solventless synthetic methodology. Using this method a variety of structural forms, which
include the drum, O-capped cluster, tetranuclear oxo cage, discrete, and polymeric compounds,
have been synthesized. All these compounds (1-11) have been characterized by spectroscopic
and analytical techniques. The new compounds, which include the hexameric drum [n-BuSn-
(O)OCOAd]6 (Ad ) adamantyl) 9, a triorganotin-based discrete structure Ph3SnO2C-C6H2-
2,4,6-Me3 (10), and a polymer Ph3SnOSO2-C6H3-2,5-Me2 (11), have been characterized by
single-crystal X-ray crystallography.
In tr od u ction
the use of high-boiling solvents under reflux conditions.
All of these reactions are considerably complex and
involve several bond-breaking and bond-forming pro-
cesses.7 Organotin cages and clusters are a particularly
attractive target because of the large structural diver-
sity that is present in this family and also because of
their importance in catalysis and other applications.7,8
By the use of solventless methodology, at ambient
temperature, we were able to synthesize in nearly
quantitative yields six different structural types; these
include cages and clusters as well as discrete and
supramolecules. We have chosen to utilize this method
for the synthesis of various known examples from
literature (1-8) and showed that solid-state synthesis
can be readily applied to these systems. In addition we
have also used this synthetic methodology for the
preparation of three new compounds, 9, 10, and 11. The
latter have also been characterized by X-ray crystal-
lography.
Traditionally solid-state synthesis has been used
primarily for alloys or for inorganic solids such as
ceramics, and most of these are high-temperature
syntheses.1-3 The application of a solventless synthetic
methodology for organic compounds that were conven-
tionally synthesized in a solvent medium is becoming
more common in recent years.4 Thus, well-known or-
ganic reactions such as the Wittig reaction, aldol
condensation, and the pinacol rearrangement have been
found to occur even in the absence of a solvent.4 In
contrast, there are virtually no reports on the applica-
tion of solventless methods for the preparation of simple
inorganic or organometallic molecules, although recently
there have been some efforts on the preparation of
coordination polymers and supramolecular arrays using
this approach. However, the latter pertain to specific
examples and are not general methods of synthesis.5,6
In the following we demonstrate a solventless synthetic
strategy that is applicable for general families of orga-
notin compounds that are traditionally synthesized by
Resu lts a n d Discu ssion
Typically the synthesis protocol consisted of grinding
the organotin reagent such as n-BuSn(O)OH, n-BuSn-
§ This paper is dedicated to Prof. R. R. Holmes on the occasion of
his 75th birghday.
* Corresponding author. Fax: (+91) 512-597-259. E-mail: vc@
iitk.ac.in.
(5) (a) Braga, D.; Maini, L.; Polito, M.; Grepioni, F. Chem. Commun.
2002, 2302. (b) Braga, D.; Maini, L.; Grepioni, F. Chem. Commun.
1999, 937. (c) Braga, D.; Grepioni, F. Chem. Soc. Rev. 1999, 29, 229.
(d) Braga, D. Cojazzi, G.; Emiliani, D.; Maini, L.; Grepioni, F. Chem.
Commun. 2001, 2272. (e) Braga, D.; Maini, L.; Mazzoti, M.; Rubini,
K.; Masic, A.; Gobetto, R.; Grepioni, F. Chem. Commun. 2002, 2296.
(6) (a) Belcher, W. J .; Longstaff, C. A.; Neckenig, M. R.; Steed, J .
W. Chem. Commun. 2002, 1602. (b) Orita, A.; J iang, L.; Nakano, T.;
Ma, N.; Otera, J . Chem. Commun. 2002, 1362. (c) Vela, M. J .; Buchholz,
V.; Enkelmann, V.; Snider, B. B.; Foxman, B. M. Chem. Commun. 2000,
2225. (d) Pedireddi, V. R.; J ones, W.; Chorlton, A. P.; Docherty, R.
Chem. Commun. 1996, 987.
† Indian Institute of Technology.
‡ University of Liverpool.
(1) (a) Anastas, P. T.; Kirchhoff, M. M. Acc. Chem. Res. 2002, 35,
686. (b) Anastas, P. T.; Warner, J . C. Green Chemistry: Theory and
Practice; Oxford Science Publication: New York, 1998. (c) Anastas P.;
Williamson, T. Green Chemistry, Frontiers in Benign Chemical Syn-
thesis and Processes; Oxford Science Publications: New York, 1998.
(2) (a) Green Chemistry: Challenges and Opportunities. Clark, J .
H. Green Chem. 1999, 1, 1. (b) The Greening of Chemistry. Clark, J .
H. Chem. Bri. 1998, Oct, 43. (c) Proving Aristotle Wrong. Bradley, D.
Chem. Bri. 2002, Sept 9, 42.
(3) Fernandez-Bertran, J . F. Pure Appl. Chem. 1999, 71 (4), 581.
(4) (a) Tanaka, K.; Toda, F. Chem. Rev. 2000, 100, 1025. (b) Toda,
F. CrystEngComm. 2002, 4, 215. (c) Cave, G. W. V.; Raston, C. L.; Scott,
J . L. Chem. Commun. 2001, 2159. (d) Rothenberg, G.; Downie, A. P.;
Raston, C. L.; Scott, J . L. J . Am. Chem. Soc. 2001, 123, 8701. (e) Cave,
G. W. V.; Raston, C. L. Chem. Commun. 2000, 2199. (f) Balema, V. P.;
Wiench, J . W.; Pruski, M.; Pecharsky, V. K. Chem. Commun. 2002,
724.
(7) (a) Chandrasekhar, V.; Nagendran, S.; Baskar, V. Coord. Chem.
Rev. 2002, 235, 1. (b) Holmes, R. R. Acc. Chem. Res. 1989, 22, 190. (c)
Tiekink, E. R. T. Appl. Organomet. Chem. 1991, 5, 1.
(8) (a) Arakawa, Y. In Chemistry of Tin; Smith, P. J ., Ed.; Blakie
Acadamic and Professional: London, 1998; p 388. (b) Evans C. J . In
Chemistry of Tin; Smith P. J ., Ed.; Blakie Acadamic and Professional:
London, 1998; p 442. (c) Gielen, M. Coord. Chem. Rev. 1996, 151, 41.
(d) Otera, J . Chem. Rev. 1993, 93, 1449.
10.1021/om030338c CCC: $25.00 © 2003 American Chemical Society
Publication on Web 08/01/2003

Synthesis of Organotin Clusters and Cages
Organometallics, Vol. 22, No. 18, 2003 3711
Sch em e 1
Sch em e 4
Sch em e 2
Sch em e 5
Sch em e 6
Sch em e 3
Ferrocenyl) is completed in 1 h to afford in about 90%
yield the hexameric drum [n-BuSn(O)OCOFc]6, 1
(Scheme 2).9a To assess if the water formed in the above
reaction is enabling a solvent type medium, we ground
the substrates in the presence of activated alumina for
scavenging the extruded water. No difference in reactiv-
ity was noted. A similar reaction was also observed with
ferrocene acetic acid to afford the drum [n-BuSn(O)-
OCOCH2Fc]6, 2 (Scheme 2).9b It is to be noted that the
products 1 and 2 represent rare examples of hexafer-
rocene arrays supported on the central stannoxane core
and possess remarkable thermal and electrochemical
stability.
The reactions of tin reagents with phosphorus-based
acids are more complex, and the nature of the product
isolated in these reactions is extremely sensitive to the
stoichiometry of the reagents and the nature of the
phosphorus-based acid.7 This remarkable product pref-
erence is also retained in the present solventless syn-
thetic methodology. Thus, the reaction of n-BuSn(O)OH
with Ph2P(O)OH in a 3:4 ratio afforded the O-capped
cluster {[n-BuSn(OH)O2PPh2]3O}[O2PPh2], 3, in 91%
yield (Scheme 3, eq 1).9c In contrast the reaction of
n-BuSn(OH)2Cl with Ph2P(O)(OH) affords the extended
tetranuclear cage {(n-Bu)2Sn2Cl2(OH)(O2PPh2)3}2, 4, in
95% yield (Scheme 3, eq 2).9d Interestingly in this cluster
four terminal Sn-Cl bonds are retained. A different
tetranuclear oxo tin cage {(n-Bu)2Sn2O[O2P(OH)-t-
Bu]4}2, 5, is formed in the reaction of n-BuSn(O)OH with
t-BuP(O)OH)2 (Scheme 3, eq 3).9e
(OH)2Cl, n-Bu2SnO, or (Ph3Sn)2O with appropriate
protic reagents such as a carboxylic acid, phosphinic
acid, or a sulfonic acid (Scheme 1).
In each case the tin reagent is a polymeric solid except
for (Ph3Sn)2O, which is a molecular solid. The protic
reagents themselves are all solids. The reactions were
monitored by 119Sn and/or 31P NMR. At the completion
of the reaction the solid mixture was extracted with
dichloromethane at room temperature and the organotin
compound was isolated by crystallization. Each of these
reactions leads to the formation of a unique organotin
compound, each representing a different structural type
(Schemes 2-6). Remarkably in every case the isolated
yields of the product are in excess of 90%. It is of interest
to note that conventionally these compounds have been
prepared by carrying out the reaction in boiling benzene
or toluene and also by using a Dean-Stark apparatus
for the dynamic removal of water formed in the reaction.
The generality of the synthetic procedure can be
widely appreciated if one considers the diversity of the
organotin precursor and the protic acid employed. Thus,
the reaction of n-BuSn(O)OH with FcCOOH (Fc )
In another variation the reaction of n-Bu2SnO with
xylyl sulfonic acid afforded the dication [n-Bu2Sn-
(9) (a) Chandrasekhar, V.; Nagendran, S.; Bansal, S.; Kozee, M. A.;
Powell, D. R. Angew. Chem., Int. Ed. 2000, 39, 1833. (b) Chan-
drasekhar, V.; Nagendran, S.; Bansal, S.; Cordes, A. W.; Vij, A.
Organometallics 2002, 21, 3297. (c) Day, R. O.; Holmes, J . M.;
Chandrasekhar, V.; Holmes, R. R. J . Am. Chem. Soc. 1987, 109, 940.
(d) Kumara Swamy, K. C.; Day, R. O.; Holmes, R. R. Inorg. Chem.
1992, 31, 4184. (e) Kumara Swamy, K. C.; Schmid, C. G.; Day, R. O.;
Holmes, R. R. J . Am. Chem. Soc. 1990, 112, 223.

3712 Organometallics, Vol. 22, No. 18, 2003
Chandrasekhar et al.
(H2O)4]2+, 6 (Scheme 4), which has a supramolecular
architecture in the solid state.10a In this reaction, not
only is water eliminated in the first step of the reaction,
but subsequently the eliminated water also serves as
the ligand for the dication. While this is not so unusual
in solution, the facility with which this dual process
happens in the solid state also suggests that this
methodology can be very useful even for complex situ-
ations. Further it is of interest to note that though only
one molecule of water is eliminated in the reaction, the
final product contains four molecules of coordinated
water. It is highly possible that the other water mol-
ecules might have been absorbed from atmospheric
moisture due to the high stability encountered with the
dication.10b
Even with triorganotin substrates such as (Ph3Sn)2O
the reactions are equally facile. Thus as shown in
Scheme 5, triorganotin carboxylates with discrete mo-
lecular structures (7 and 8) are formed.11a,b
In any of the above reactions (Schemes 1-5), no
visible melt was observed during any stage of the
reaction and the solid powder was completely free
flowing during the entire reaction condition. This is in
contrast to most organic solventless reactions, where a
eutectic melt has been detected.4a,c As observed in the
recently reported phosphonium bromide4f synthesis, we
believe that mechanical grinding provides sufficiently
close proximity and contact between reactants for mass
transfer to occur. To check if the solid-state reactions
proceed by loss of crystallinity, we have chosen a test
case. Thus, in the preparation of the extended tetra-
nuclear cage {(n-Bu)2Sn2Cl2(OH)(O2PPh2)3}2, 4, the
powder X-ray diffraction at various time intervals
(Figure 1) shows the evolution of peaks corresponding
to the formation of the product. The final XRD compares
well with that of the authentic sample. It is to be noted
that at all stages the crystalline nature of the reaction
mixture is maintained, as indicated by the presence of
clear diffraction pattern. In the reactions leading to
products 7 and 8 (Scheme 5), the solid mixtures,
although they did not turn into a melt, were marked
by a slight amount of stickiness. The progress of the
formation of the cages {(n-Bu)2Sn2Cl2(OH)(O2PPh2)3}2,
4, and {(n-Bu)2Sn2O[O2P(OH)-t-Bu]4}2, 5, has been
monitored by 31P NMR. In the preparation of the
extended cluster 4 it was observed that the reaction
progresses rapidly in the first 30 min and is completed
after 1 h. 31P NMR spectra (in CDCl3) of the solid
obtained by grinding n-BuSn(OH)2Cl with Ph2P(O)(OH)
at various time intervals are shown in Figure 2. The
chemical shifts observed in the 31P NMR spectrum (60
min) match with those of the authentic sample 4
prepared conventionally. Similarly the tetranuclear cage
{(n-Bu)2Sn2O[O2P(OH)- t-Bu]4}2, 5, also is formed quite
rapidly and is complete in 2 h (Figure 3).
F igu r e 1. Powder X-ray diffraction pattern of the solid
obtained on grinding n-BuSn(OH)2Cl with Ph2P(O)(OH):
(a) immediately after mixing the reactants, (b) after 15 min,
(c) after 25 min, (d) after 40 min, and (e) after 60 min of
grinding. The pattern (e) matches exactly with the powder
XRD pattern of the product 4 synthesized by conventional
methods.9d
we wished to extend this methodology to new com-
pounds as well. Accordingly the reaction of n-BuSn(O)-
OH was carried out with adamantane carboxylic acid
by using both solventless and conventional techniques.
Similarly the reactions of Ph3SnOSnPh3 with 2,4,6-
Me3C6H2COOH or 2,5-Me2C6H3SO3H were also carried
out by both methods (Schemes 2, 5, 6). Irrespective of
the method used, a unique product was isolated in high
yields from each reaction. The products formed in these
reactions, viz., [n-BuSn(O)OC(O)Ad]6 (9), Ph3SnO2C-
C6H2-2,4,6-Me3 (10), and Ph3SnOSO2-C6H3-2,5-Me2 (11),
were characterized by spectroscopic methods as well as
by X-crystallography.
Although the efficacy of the solventless methodology
is proven beyond doubt (as shown vide supra) for the
preparation of a variety of known organotin compounds,
(10) (a) Chandrasekhar, V.; Boomishankar, R.; Singh, S.; Steiner,
A.; Zacchini, S. Organometallics 2002, 21, 4575. (b) Chandrasekhar,
V.; Boomishankar, R.; Steiner, A.; Bickley, J . F. Organometallics 2003,
in press.
(11) (a) Swisher, R. G.; Vollano, J . F.; Chandrasekhar, V.; Day, R.
O.; Holmes, R. R. Inorg. Chem. 1984, 23, 3147. (b) Molloy, K. C.;
Blunden, S. J .; Hill, R. J . Chem. Soc., Dalton Trans. 1988, 1259.
Thus, 119Sn NMR chemical shifts of 9, 10, and 11 are
characterized by singlets at -486.7, -112.5, and -238.1
ppm, respectively. The molecular structures of these
compounds were confirmed by X-ray crystal structures.

Synthesis of Organotin Clusters and Cages
Organometallics, Vol. 22, No. 18, 2003 3713
F igu r e 2. 31P NMR spectra (in CDCl3) of the solid obtained
by grinding n-BuSn(OH)2Cl with Ph2P(O)(OH): (a) after
15 min, (b) after 30 min, (c) after 45 min, and (d) after 60
min of grinding. The chemical shifts in spectrum (d) match
that of the cage {(n-Bu)2Sn2Cl2(OH)(O2PPh2)3}2, 4, pre-
pared by conventional methods.9d
F igu r e 4. (a) DIAMOND view of the drum 9 (n-butyl
groups on tin have been omitted for clarity) and (b) ORTEP
view of the Sn6O6 core are shown. Selected bond lengths
(Å) and bond angles (deg) for 9: Sn2-O1 2.078(15), Sn1*-
O2* 2.078(9), Sn3-O2* 2.088(20), Sn3-O1 2.094(4), Sn2-
O3* 2.092(25), Sn1*-O3* 2.090(13), Sn3-O3 2.098(3),
Sn2*-O2* 2.094(5), Sn2*-O3* 2.092(25), Sn3-O9 2.162-
(15), Sn1-O8 2.168(4), Sn1-O5 2.181(17), Sn2-O4 2.161-
(28), Sn2-O7 2.162(14), Sn3*-O6 2.160(11), Sn1-O2-
Sn3* 132.93(16), Sn3*-O1*-Sn2* 131.47(16), Sn2*-O3-
Sn1 133.69(17), Sn1-O3-Sn3 100.18(14), Sn3-O1-Sn1
100.29(14), Sn1-O1-Sn2 99.90(13), Sn2-O2-Sn1 99.78-
(13), O2-Sn2-O3* 78.11(13), O2-Sn3*-O3* 78.12(13).
F igu r e 3. 31P NMR spectra (in CDCl3) of the solid obtained
by grinding n-BuSn(O)OH with t-BuP(O)(OH)2: (a) after
10 min, (b) after 25 min, (c) after 50 min, (d) after 80 min,
and (e) after 120 min of grinding. The chemical shifts in
spectrum (e) match that of the cage {(n-Bu)2Sn2O[O2P(OH)-
t-Bu]4}2, 5, prepared by conventional methods.9e
Molecu la r Str u ctu r es of 9, 10, a n d 11. The mo-
lecular structures of 9, 10, and 11 are shown in Figures
4, 5, and 6, respectively. The molecular structure of 9
shows that it possesses the well-known drum type of
architecture.7,9a Thus the organotin cluster consists of
a Sn6O6 core. This core is comprised of two puckered
Sn3O3 units that serve as top and bottom faces of the
drum. The fusion of the two Sn3O3 units leads to the
generation of six Sn2O2 distannoxane rings which form
the sides of the drum. Alternate tin centers in the Sn6O6
core are bridged by the adamantane carboxylate in a
symmetrical isobidentate manner. The metric param-
eters found for this compound are normal and are
summarized in the caption of Figure 4.
5). The tin is involved in four covalent bonds having a
distorted tetrahedral geometry about the tin center. The
carboxyl oxygen is involved in a fifth weaker bonding
interaction with tin along a tetrahedral face. Accord-
ingly, two types of Sn-O distances are seen. Thus, the
Sn1-O1 distance is 2.071(6) Å and corresponds to the
Sn-O covalent bond. The bond distance between the
tin center and the carboxyl oxygen (Sn1-O2) is 2.769-
(7) Å. The sum of the van der Waals radii of tin and
oxygen is 3.7 Å.12 In view of this and also in view of
literature precedents7 it can be proposed that a coordi-
The molecular structure of 10 shows that the trior-
ganotin carboxylate adopts a discrete structure (Figure
(12) Bondi, A. J . Phys. Chem. 1964, 68, 441.

3714 Organometallics, Vol. 22, No. 18, 2003
Chandrasekhar et al.
Each tin has trigonal bipyramidal geometry with the
axial positions being taken up by the oxygen atoms.
Con clu sion
In summary, we have shown that an ambient tem-
perature, solventless solid-state synthesis is a conve-
nient way for the preparation of various types of
organotin clusters. Both known and new organotin
compounds have been prepared in excellent yield by the
use of this methodology. This is the first example of the
application of such a benign solid-state solvent-free
synthetic methodology for the construction of compli-
cated clusters.
F igu r e 5. ORTEP view of 10. Selected bond lengths (Å)
and bond angles (deg): Sn1-O1 2.071(6), Sn1-O2 2.769-
(7), Sn1-C1 2.110(9), Sn1-C7 2.120(9), Sn1-C13 2.135-
(8), C19-O1 1.309(11), C19-O2 1.230(12), O1-C19-O2
122.85(86), O1-Sn1-C13 95.20(28), O1-Sn1-C1 114.6-
(3), O1-Sn1-C7 105.75(31), C7-Sn1-C1 116.19(32), C13-
Sn1-C1 112.25(31).
Exp er im en ta l Section
The following chemicals were purchased and used as such
without further purification: ferrocenemonocarboxylic acid
(Aldrich), n-butyltin hydroxide oxide (Aldrich), n-butyltin
chloride dihydroxide (Aldrich), n-dibutyltin oxide (Aldrich), bis-
(triphenyltin) oxide (Aldrich), tert-butylphosphonic acid (Ald-
rich), diphenyl phosphinic acid (Aldrich), 2-aminobenzoic acid
(Fluka), 4-chlorobenzoic acid (Fluka), 2,6-dimethylbenzoic acid
(Aldrich), 2,4,6-trimethylbenzoic acid (Fluka).
Ferroceneacetic acid13 and 2,5-dimethylbenzene sulfonic
acid14 were prepared using literature procedures. Melting
points were measured using a J SGW melting point apparatus
and are uncorrected. Elemental analyses were carried out
using a Thermoquest CE instruments model EA/110 CHNS-O
elemental analyzer. 1H, 31P, and 119Sn NMR spectra were
obtained on a J EOL-J NM LAMBDA 400 model spectrometer
using CDCl3 solutions (unless specified) with shifts referenced
to tetramethylsilane (1H), 85% H3PO4 (31P), and tetramethyltin
(
119Sn), respectively. 31P and 119Sn NMR were recorded under
broad-band decoupled conditions.
Syn th esis. Gen er a l P r oced u r e. A typical synthesis in-
volves grinding the organotin precursor with a protic acid (in
stoichiometric ratio) at room temperature using a mortar and
a pestle. Most of the organotin starting materials are insoluble
white solids. Increase in solubility of the mixture with time
along with noticeable morphological changes reveals the
progress of the reaction. When the solid is completely soluble,
a minimum amount of dichloromethane is added and filtered
through a G4 frit to remove any insoluble impurities present.
Evaporation of the filtrate affords the product. The products
119
1-8 were characterized by spectroscopic techniques (1H,
-
Sn, and where required 31P NMR) and elemental analysis. The
new compounds 9-11 were characterized by spectroscopic,
analytical, and single-crystal X-ray diffraction techniques.
The stoichiometric ratios of the reactants, the yield of the
product, and the 119Sn chemical shifts (in CDCl3) are given
below.
F igu r e 6. (a) ORTEP view of 11 shown at 50% probability
level. The asymmetric unit contains two molecules. (b)
DIAMOND view showing the propagation of 11 into a
linear polymeric chain. Selected bond lengths (Å) and
bond angles (deg): Sn1-O1 2.273(3), Sn2-O2 2.280(3),
Sn1-C7 2.114(5), Sn1-C1 2.124(6), Sn1-C1* 2.124(6),
Sn2-C11 2.109(6), Sn2-C11* 2.109(6), Sn2-C17 2.110-
(5), Sn1-O3 1.435(5), O1-Sn1-O1* 174.38(9), C1-Sn1-
C1* 117.31(18), C1-Sn1-C7 121.35(10), C7-Sn1-C1
121.35(10), O2-S1-O1 107.56(15), O2-Sn2-O2* 172.53-
(9), C11*-Sn2-C11 119.88(19), C11-Sn2-C17 120.06(10),
C17-Sn2-C11* 120.06(10).
1. [n -Bu Sn (O)OCOF c]6: n-BuSn(O)OH (0.10 g, 0.47 mmol),
ferrocene carboxylic acid (0.11 g, 0.47 mmol), grinding time:
60 min. Product yield: 0.18 g (90%). Mp: 244 °C (dec) (lit9a
mp: 244 °C (dec)). 119Sn NMR (CDCl3, ppm): -486.6 (lit.
-486.6).9a
2. [n -Bu Sn (O)OCOCH2F c]6: n-BuSn(O)OH (0.10 g, 0.47
mmol), ferrocene carboxylic acid (0.12 g, 0.49 mmol), grinding
time: 50 min. Product yield: 0.19 g (91%). Mp: 93 °C (lit.9b
mp: 92 °C). 119Sn NMR (CDCl3, ppm): -483.2 (lit. -483.2).9b
3. {[n -Bu Sn (OH)O2P P h 2]3O}[O2P P h 2]: n-BuSn(O)OH (0.19
g, 0.90 mmol), diphenylphosphinic acid (0.26 g, 1.19 mmol),
grinding time: 40 min. Product yield: 0.40 g (91%). Mp: 196
native interaction exists between O2 and Sn1. It is
known that discrete structures are preferred for triph-
enyltin arylcarboxylates.7
The molecular structure of 11 is shown in Figure 6.
Two molecules are present in the asymmetric unit cell.
The molecule adopts a polymeric structure in the solid
state. Successive triphenyltin units are linked by a
bridging sulfonate moiety. Unlike many polymeric tri-
organotin carboxylates which adopt zigzag conforma-
tions, it may be noticed that the tin centers in the
polymeric chain of 11 are arranged in a linear manner.
(13) (a) Graham, P. J .; Lindsey, R. V.; Parshall, G. W.; Peterson,
M. L.; Whitman, G. M. J . Am. Chem. Soc. 1957, 79, 3416. (b) Rinehart,
K. L.; Curby, R. J .; Sokol, P. E. J . Am. Chem. Soc. 1957, 79, 3420.
(14) Furniss, B. S.; Hannaford, A. J .; Smith, P. W. G.; Tatchell, A.
R. Vogel’s Text Book of Practical Organic Chemistry, 5th ed.; ELBS
and Longman: London, 1989.

Synthesis of Organotin Clusters and Cages
Organometallics, Vol. 22, No. 18, 2003 3715
Ta ble 1. Cr ysta l Da ta a n d Str u ctu r e Refin em en t P a r a m eter s for 9, 10, a n d 11
9
10
11
empirical formula
fw
C
90H132O18Sn6
C
28H26O2Sn
C26H24O3SSn
535.20
2214.10
513.18
temperature
wavelength
cryst syst
space group
unit cell dimens
213(2) K
0.71073 Å
monoclinic
P2(1)/c
a ) 14.885(3) Å, R ) 90°
b ) 16.787(4) Å, â ) 104.26(2)°
c )19.457(3) Å, γ ) 90°
4712.0(15) Å3
213(2) K
0.71073 Å
orthorhombic
Iba2
a ) 17.662(3) Å, R ) 90°
b ) 40.678(6) Å, â ) 90°
c ) 6.6149(8) Å, γ ) 90°
4752.4(12) Å3
150(2) K
0.71073 Å
monoclinic
C2/c
a ) 18.7581(11) Å, R ) 90°
b ) 49.196(3) Å, â ) 132.6500(10)°
c ) 13.7580(8) Å, γ ) 90°
9338.1(9) Å3
volume
Z
2
8
16
density (calcd)
abs coeff
1.561 Mg/m3
1.434 mg/m3
1.523 Mg/m3
1.628 mm-1
1.096 mm-1
1.209 mm-1
F(000)
cryst size
θ range for data collection
index ranges
2232
2080
4320
0.1 × 0.1 × 0.2 mm3
0.4 × 0.4 × 0.3 mm3
1.89 to 24.17°
-20 e h e 20, -46 e k e 46,
-7 e l e 7
0.4 × 0.3 × 0.15 mm3
1.86 to 24.28°
1.53 to 25.02°
-17 e h e 17, -19 e k e 19,
-22 e l e 22
29 646
7469 [R(int) ) 0.0490]
97.8%
-22 e h e 22, -58 e k e 38,
-15 e l e 16
24 453
8271 [R(int) ) 0.0220]
99.8%
semiempirical from equivalents
full-matrix least-squares on F2
8271/0/569
no. of reflns collected
no. of ind reflns
completeness to θ
abs corr
14 807
3697 [R(int) ) 0.1383]
98.3%
none
none
refinement method
no. of data/restrains/
params
full-matrix least squares on F2
7469/1305/624
full-matrix least squares on F2
3697/1/283
goodness-of-fit on F2
final R indices [I>2σ(I)]
R indices (all data)
largest diff peak and hole
1.026
0.959
1.149
R1 ) 0.0428, wR2 ) 0.0966
R1 ) 0.0520, wR2 ) 0.1065
0.675 and -0.856 e Å-3
R1 ) 0.0489, wR2 ) 0.1093
R1 ) 0.0717, wR2 ) 0.1182
0.878 and -0.934 e Å-3
R1 ) 0.0358, wR2 ) 0.0847
R1 ) 0.0400, wR2 ) 0.0865
0.887 and -0.449 e Å-3
°C (dec) (lit.9c mp: 198 °C (dec)). 119Sn NMR (CDCl3, ppm):
g, 3.00 mmol) in toluene (70 mL) was heated under reflux for
6 h. The water formed in the reaction was removed by using
a Dean-Stark apparatus. The reaction mixture was filtered
and evaporated to afford a white solid whose analytical and
spectroscopic data matched with the sample obtained in the
preparative route 9a. Yield: 0.92 g (83%).
2
-498.5 (t, J (Sn-O-P) ) 132 Hz) (lit. -498.5).9c
4. {(n -Bu )2Sn 2Cl2(OH)(O2P P h 2)3}2: n-BuSn(OH)2Cl (0.10
g, 0.40 mmol), diphenylphosphinic acid (0.13 g, 0.60 mmol),
grinding time: 60 min. Product yield: 0.21 g (95%). Mp: 256
°C (lit.9d mp: 258-260 °C). 119Sn NMR (CDCl3, ppm): -507.4
(t, 2J (Sn-O-P) ) 222 Hz), -615.4 (m); (lit. -507.4, -615.4).9d
5. {(n -Bu )2Sn 2O[O2P (OH)-t-Bu ]4}2: n-BuSn(O)OH (0.10 g,
0.47 mmol), tert-butylphosphonic acid (0.13 g, 0.95 mmol),
grinding time: 120 min. Product yield: 0.20 g (92%). Mp: 278
°C (dec) (lit.9e mp: 280 °C (dec)). 119Sn NMR (CDCl3, ppm):
10. Syn th esis of P h 3Sn OC(O)-C6H2-2,4,6- Me3. (a ) Sol-
ven tless Meth od . The procedure described vide supra was
followed. The quantities of the reactants are Ph3SnOSnPh3
(0.29 g, 0.40 mmol) and 2,4,6-trimethylbenzoic acid (0.13 g,
0.80 mmol). Grinding time: 30 min. Crystals suitable for
single-crystal X-ray diffraction were obtained by vapor diffu-
sion of n-hexane into the solution of 10 in CH2Cl2 at room
temperature. Yield: 0.38 g (93%). Mp: 110 °C. Anal. Calcd
for C28H26O2Sn: C, 65.53; H, 5.11. Found: C, 65.21; H, 5.01.
2
-630.4 (tt, J (Sn-O-P) ) 239, 286 Hz) (lit. -630.4).9e
6. {n -Bu 2Sn (H2O)4}2+2{2,5-Me2-C6H3SO3}-: n-Bu2SnO (0.10
g, 0.40 mmol), 2,5-dimethylbenzene sulfonic acid (0.15 g, 0.80
mmol), grinding time: 80 min. Product yield: 0.24 (90%).
Mp: 273 °C (lit.10a mp: 273 °C). 119Sn NMR (in CD3OD):
-360.0 (s) (lit. -360.04).10a
1H NMR (CDCl3, ppm): 2.16 (s, 9H, CH3); 6.72 (s, 2H,
119
aromatic); 7.37-7.38 and 7.71-7.73 (m, 15H, aromatic).
Sn NMR (CDCl3, ppm): -112.5 (s).
-
7. P h 3Sn OC(O)-C6H4-2-NH2: (Ph3Sn)2O (0.13 g, 0.18 mmol),
2-aminobenzoic acid (0.05 g, 0.36 mmol), grinding time: 30
min. Product yield: 0.17 g (96%). Mp: 108 °C (lit.11a mp: 108-
109 °C). 119Sn NMR (CDCl3, ppm): -119.5 (s) (lit. -119.5).11a
8. P h 3Sn OC(O)-C6H4-4- Cl: (Ph3Sn)2O (0.11 g, 0.18 mmol),
4-chlorobenzoic acid (0.05 g, 0.31 mmol), grinding time: 30
min. Product yield: 0.15 g (96%). Mp: 129-133 °C (lit.11b mp:
128-135 °C). 119Sn NMR (CDCl3, ppm): -108.2 (s) (lit.
-108.2).11b
9. Syn th esis of [n -Bu Sn (O)OCO-Ad ]6. (a ) Solven tless
Meth od . The general procedure as described above was
followed. The quantities of the reactants are n-BuSn(O)OH
(1.00 g, 4.7 mmol) and adamantane-1-carboxylic acid (0.86 g,
4.7 mmol). Grinding time: 30 min. Crystals suitable for single-
crystal X-ray diffraction were obtained by the slow evaporation
of a solution of 9 in CHCl3 at room temperature. Yield: 0.97
g (93%). Mp: 280 °C (dec). Anal. Calcd for C90H144O18Sn6: C,
48.55; H, 6.52. Found: C, 48.51; H, 6.40. 1H NMR (CDCl3,
ppm): 0.84 (t, 3H, butyl CH3); 1.07-1.11 (m, 2H, butyl CH2);
1.28-1.37 (m, 2H, butyl CH2); 1.56-1.64 (m, br, 8H, ada-
mantly CH2 and SnCH2); 1.78 (d, 6H, adamantly CH2); 1.91
(s, br, 3H, adamantly CH). 119Sn NMR (CDCl3, ppm): -486.7
(s).
(b) Con ven tion a l Meth od . The procedure given in 9b was
followed. The quantities of the reactants used are Ph3-
SnOSnPh3 (0.72 g, 1.00 mmol) and 2,4,6-trimethylbenzoic acid
(0.33 g, 2.00 mmol). Yield: 0.95 g (93%). Analytical and
spectroscopic data of this product were exactly similar to those
obtained from the preparative route 10a.
(11) Syn th esis of [P h 3Sn OSO2-C6H3-2,5-Me2]n . (a ) Sol-
ven tless Meth od . The procedure as described above was
followed. The quantities of the reactants taken are Ph3-
SnOSnPh3 (0.20 g, 0.27 mmol) and 2,5-dimethylbenzene sul-
fonic acid (0.10 g, 0.55 mmol). Grinding time: 20 min. Crystals
suitable for single-crystal X-ray diffraction were obtained by
the slow evaporation of a solution of 11 in a mixture of
methanol and toluene. Yield: 0.25 g (85%). Mp: 238 °C. Anal.
Calcd for C26H24O3SSn: C, 58.34; H, 4.51. Found: C, 58.11; H,
4.24. 1H NMR: 2.27 (s, 3H, CH3), 2.55 (s, 3H, CH3), 7.09-
7.90 (m, 18H, aromatic). 119Sn (DMSO-d6, ppm): -238.1.
(b) Con ven tion a l Meth od . A mixture of Ph3SnOSnPh3
(1.00 g, 1.40 mmol) and 2,5-dimethylbenzene sulfonic acid (0.52
g, 2.80 mmol) in toluene (60 mL) was heated under reflux for
6 h using a Dean-Stark apparatus to remove the water formed
in the reaction by azeotropic distillation. A white solid formed
in the reaction was filtered by a sintered funnel and dried.
(b) Con ven tion a l Meth od . A mixture of n-BuSn(O)OH
(0.63 g, 3.00 mmol) and adamantane-1-carboxylic acid (0.54

3716 Organometallics, Vol. 22, No. 18, 2003
Chandrasekhar et al.
Analytical and spectroscopic data of the white solid matched
with the sample obtained from the procedure 11a. Yield: 1.15
g (77%).
idealized positions, and a riding model was used. Non-
hydrogen atoms were refined with anisotropic displacement
parameters. Powder X-ray diffraction patterns were recorded
using a Rich-Seifert X-ray diffractometer (model Isodebyeflux
2002) with Cu KR radiation and a Ni filter.
X-r a y Cr ysta llogr a p h y. Colorless blocklike crystals of 9,
10, and 11 suitable for single-crystal X-ray diffraction were
loaded on a Bruker AXS Smart Apex CCD diffractometer. The
details pertaining to the data collection and refinement are
given in Table 1. In the crystal structure of 9 two adamantyl
framework carbons and two butyl carbons were disordered.
All the structures were solved by direct methods using
SHELXS-97 and refined by full-matrix least squares on F2
using SHELXL-97.15,16 All hydrogen atoms were included in
Ack n ow led gm en t. We are thankful to the Depart-
ment of Science and Technology (DST), New Delhi,
India, for financial support. A.S. thanks EPSRC (Engi-
neering and Physical Sciences Research Council), U.K.
for financial support.
(15) Scheldrick, G. M. SHELXL-97, Program for Crystal Structure
Analysis (release 97-2); University of Go¨ttingen: Go¨ttingin, Germany,
1998.
(16) Sheldrick, G. M. SHELXTL, Version 5.03; Siemens Analytical
X-ray Division: Madison, WI, 1994.
Su p p or tin g In for m a tion Ava ila ble: This material is
available free of charge via the Internet at http://pubs.acs.org.
OM030338C