Structural diversity in organotin compounds derived from bulky monoaryl phosphates: Dimeric, tetrameric, and polymeric tin phosphate complexes

Article abstract of DOI:10.1002/ejic.200701032

Monoaryl phosphates with a bulky aryl substituent have been used to synthesize new organotin clusters and polymers. The equimolar reaction between 2,6-diisopropylphenylphosphate (dipp-H₂) and Me₂SnCl ₂ in ethanol at 25°C leads to the formation of [Me ₂Sn(μ₃-dipp)]_n (1), while the reaction of 2,6-dimethylphenylphosphate (dmpp-H₂) with Me₂SnCl ₂ in either a 1:1 or 2:1 molar ratio proceeds to produce exclusively [Me₂Sn(μ-dmpp-H)₂]_n·nH₂O (2). Compounds 1 and 2 are 1D polymers with different architectures. In compound 1, the tin atom is five-coordinate (trigonal bipyramidal). Each dipp ligand bridges three different tin atoms to form an infinite ladder-chain structure. In 2, each six-coordinate (octahedral) tin atom is surrounded by four phosphate oxygen atoms originating from four different bridging dmpp-H ligands, thus forming a spirocyclic coordination polymeric chain. The use of nBu ₂SnO as the diorganotin source in its reaction with dipp-H ₂ leads to the isolation of dimeric [nBu₂Sn(μ-dipp-H) (dipp-H)]₂ (4), which contains a central Sn₂O ₄P₂ unit. There are two chemically different half molecules of 4 in the asymmetric part of the unit cell and hence it actually exists as a 1:1 mixture of [nBu₂Sn(μ-dipp-H)(dipp-H)]₂ and [nBu₂Sn(μ-dipp)(dipp-H₂)]₂ in the solid state. The reaction of the monoorgano tin precursor nBuSn(O)(OH)·xH ₂O with dipp-H₂ takes place in acetone at room temperature to yield the tetrameric cluster 5, which has different structures in the solution and in the solid state. ³¹P NMR spectroscopy clearly suggests that 5 has the formula [nBu₄Sn₄(μ-O) ₂(μ-dipp-H)₈] in solution. The single-crystal Xray diffraction studies in the solid state, however, reveal that compound 5 exists as [nBu₄Sn₄(μ-OH)₂(μ-dipp-H) ₆(μ-dipp)₂]. The use of compounds 1-4 as possible precursors for the preparation of ceramic tin phosphate materials has been investigated. The thermolysis of 1 at 500°C leads to the formation of quantitative amounts of Sn₂P₂O₇, while the thermolysis of 2, 3, and 4 under similar conditions results in the formation of SnP₂O₇. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.

Full text of DOI:10.1002/ejic.200701032

FULL PAPER
DOI: 10.1002/ejic.200701032
Structural Diversity in Organotin Compounds Derived from Bulky Monoaryl
Phosphates: Dimeric, Tetrameric, and Polymeric Tin Phosphate Complexes
Ramaswamy Murugavel,*[a] Swaminathan Shanmugan,[a] and Subramaniam Kuppuswamy[a]
Keywords: Organotin compounds / Polymers / Cluster compounds / Precursors / X-ray structures
Monoaryl phosphates with a bulky aryl substituent have
cules of 4 in the asymmetric part of the unit cell and hence
been used to synthesize new organotin clusters and poly- it actually exists as a 1:1 mixture of [nBu2Sn(µ-dipp-H)(dipp-
mers. The equimolar reaction between 2,6-diisopropylphen-
ylphosphate (dipp-H2) and Me2SnCl2 in ethanol at 25 °C
leads to the formation of [Me2Sn(µ3-dipp)]n (1), while the re-
action of 2,6-dimethylphenylphosphate (dmpp-H2) with
Me2SnCl2 in either a 1:1 or 2:1 molar ratio proceeds to pro-
duce exclusively [Me2Sn(µ-dmpp-H)2]n·nH2O (2). Com-
pounds 1 and 2 are 1D polymers with different architectures.
In compound 1, the tin atom is five-coordinate (trigonal bipy-
ramidal). Each dipp ligand bridges three different tin atoms
to form an infinite ladder-chain structure. In 2, each six-coor-
dinate (octahedral) tin atom is surrounded by four phosphate
oxygen atoms originating from four different bridging dmpp-
H ligands, thus forming a spirocyclic coordination polymeric
chain. The use of nBu2SnO as the diorganotin source in its
reaction with dipp-H2 leads to the isolation of dimeric
[nBu2Sn(µ-dipp-H)(dipp-H)]2 (4), which contains a central
Sn2O4P2 unit. There are two chemically different half mole-
H)]2 and [nBu2Sn(µ-dipp)(dipp-H2)]2 in the solid state. The
reaction of the monoorgano tin precursor nBuSn(O)(OH)·
xH2O with dipp-H2 takes place in acetone at room tempera-
ture to yield the tetrameric cluster 5, which has different
structures in the solution and in the solid state. 31P NMR
spectroscopy clearly suggests that
5 has the formula
[nBu4Sn4(µ-O)2(µ-dipp-H)8] in solution. The single-crystal X-
ray diffraction studies in the solid state, however, reveal that
compound 5 exists as [nBu4Sn4(µ-OH)2(µ-dipp-H)6(µ-dipp)2].
The use of compounds 1–4 as possible precursors for the
preparation of ceramic tin phosphate materials has been in-
vestigated. The thermolysis of 1 at 500 °C leads to the forma-
tion of quantitative amounts of Sn2P2O7, while the thermoly-
sis of 2, 3, and 4 under similar conditions results in the forma-
tion of SnP2O7.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2008)
a molecular weight of 4000, can be isolated from 2,6-diiso-
propylphenylphosphate and a suitable aluminum precursor
in nonaqueous medium.[4]
Introduction
The use of ligands that contain more than one hydroxy
group on a central main group element for the purpose of
building multinuclear metal cages, clusters, and polymeric
structures has gained greater momentum in the last two
decades.[1] One of the main reasons for this flare-up of ac-
tivity in this area is due to the realization that such cage
structures could be transformed into super-structures that
would resemble zeolite-like materials.[2] We have recently
shown that 2,6-diisopropylphenylphosphate (dipp-H2) is an
ideal starting point for the preparation of both main group
and transition-metal phosphate clusters that self-assemble
through noncovalent interactions into zeolite-like materi-
als.[3–5] For example, by using zinc as the representative ex-
ample, it is possible to build hierarchical zinc–dipp struc-
tures in a systematic way by changing the coligands used.[3]
Similarly large aluminophosphate clusters, often exceeding
Fascinated by the variety of structures obtained for di-
valent transition metals such as zinc, manganese, and cop-
per as well as the trivalent aluminum with dipp-H2, we
wished to unravel the types of structures that would be
formed in the case of tetravalent tin. Interaction of or-
ganotin precursors with acidic hydrogen-containing com-
pounds has been extensively studied in the 1980s and 1990s
by Holmes et al., who unraveled several new structural
types for tin.[6] After a dormant period in between, Chand-
rasekhar et al.[7] and others[8–10] showed in recent years that
newer and more interesting tin aggregates and polymers
could be synthesized by employing a variety of exotic and
suitably designed carboxylic acids, phosphinic acids, sul-
fonic acids, and other acidic proton-containing main group
ligands. Thus, while the interaction of both phosphinic[11–13]
and phosphonic acids[11,14–17] with organotin precursors in
the assembly of organostannoxane cages has been a subject
of intense investigation for sometime now, the use of phos-
phate esters for this purpose has been limited to a few spo-
radic reports.[18] Owing to the important role played by
bulky substituents in main group chemistry in recent times,
[a] Department of Chemistry, Indian Institute of Technology –
Bombay,
Powai, Mumbai 400076, India
Fax: +22-2572-3480
E-mail: rmv@chem.iitb.ac.in
Supporting information for this article is available on the
WWW under http://www.eurjic.org or from the author.
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Organotin Compounds Derived from Bulky Monoaryl Phosphates
in terms of modulating the size and shape of the molecules
It is interesting to note that the equimolar reaction in-
formed, we have now investigated the reactions of two volving dipp-H2 produces the 1:1 product 1, while the same
monoarylphosphate esters, dipp-H2 and dmpp-H2 {[(2,6- reaction under identical conditions involving dmpp-H2 re-
Me2C6H3O)P(O)(OH)2]} with organotin precursors such as sults in the formation of the 1:2 product 2. Intrigued by this
Me2SnCl2, nBu2SnO, and nBu(O)(OH)·xH2O. The results observation, we investigated the 1:2 reaction between dipp-
of this investigation, which describe the synthesis and struc- H2 and Me2SnCl2 in ethanol and found that the reaction
tural characterization of polymeric as well as cagelike tin proceeds smoothly to yield [Me2Sn(µ-dipp-H)2]n·nH2O (3).
phosphates, are reported herein.
Thus, the stoichiometric control works very well in the case
of dipp-H2 and it is possible to isolate both the 1:1 and 1:2
products (1 and 3), while reactions involving dmpp-H2 do
not show any such control and always yield 2 and no
[Me2Sn(µ3-dmpp)]n. It appears that because of the smaller
aryl substituent on dmpp-H2, two dmpp-H ligands could
be accommodated around tin. On the other hand, due to
Results and Discussion
Synthesis and Characterization of [Me2Sn(µ3-dipp)]n (1),
[Me2Sn(µ-dmpp-H)2]n·nH2O (2), and [Me2Sn(µ-dipp-H)2]n·
nH2O (3)
The reactions of Me2SnCl2 with arylphosphates dipp-H2 the larger aryl substituent on dipp-H2, compound 3 could
and dmpp-H2 were initially carried out in tetrahydrofuran be obtained only when the reaction was carried out with
in the presence of Et3N as the HCl scavenger under anhy- two equivalents of dipp-H2, which suggests that steric con-
drous conditions at 65 °C. The product obtained by this trol plays a significant role in these reactions.
route in each case was a mixture of compounds, which
Analytically pure 1 and 2 were directly obtained as single
could not be either separated or completely characterized. crystals by crystallization of the respective reaction mix-
Hence, these reactions were carried out at room tempera- tures at room temperature. Compound 3 was obtained as
ture in ethanol or methanol in the absence of any HCl scav- an insoluble powder. The compounds, once formed, were
enger. Thus, the reaction between dipp-H2 and Me2SnCl2 found to be insoluble in all common organic solvents such
in ethanol at 25 °C leads to the formation of [Me2Sn(µ3- as hydrocarbons, alcohols, ether, halogenated solvents, and
dipp)]n (1). On the other hand, the reaction of dmpp-H2 water, probably because of the formation of polymeric
with Me2SnCl2 takes place in methanol to produce structures (vide infra). Hence, the characterization of 1–3
[Me2Sn(µ-dmpp-H)2]n·nH2O (2) (Scheme 1).
could be carried out only in the solid state. The analytical
Scheme 1. Synthesis of polymeric organotin phosphates 1–3 and their thermolysis.
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data obtained for 1 indicates the incorporation of one dipp Sn2O3 “T” around the metal. The net result of this coordi-
ligand per tin with a molecular formula of [Me2Sn(µ3- nation mode is the formation of a double-chain polymer
dipp)]. The elemental analysis obtained for 2 clearly indi- made up of fused eight-membered rings (Figure 2). Each of
cates the presence of two dmpp ligands for each tin with a the fused Sn2O4P2 rings adopts a sofa conformation, and
molecular formula of [Me2Sn(µ3-dmpp-H)2]·H2O. The re- hence the polymeric double-chain is nonplanar.
sults from infrared spectroscopy further lend support to this
formulation, though a strong broad absorption band at
around 2360 cm–1 that corresponds to the presence of an
unreacted P–OH group in the cases of 2 and 3 is present,
while this absorption band is absent in 1. The IR spectrum
of 1 shows broad absorption bands at 1141 and 1031 cm–1
that can be assigned to the Sn–O–P symmetric and asym-
metric stretching vibrations. The absorption bands occur-
ring at 2967 and 2929 cm–1 are due to aliphatic C–H vi-
brations. Similarly, the IR spectrum of 2 shows absorption
Figure 2. Polymeric structure of 1 in the crystal. The hydrogen
bands at 1144 and 1112 cm–1 resulting from Sn–O–P sym-
atoms and the isopropyl carbon atoms are omitted for clarity.
metric and asymmetric stretching vibrations. The absorp-
tion bands at 2956 and 2926 cm–1 are due to aliphatic C–H
All the three Sn–O bonds in the molecule are almost of
vibrations.
equal length. The P–O(M) bonds [1.495(7)–1.512(6) Å] are
shorter than the P–O(C) bond [1.614(8) Å]. The bond
angles around the tin atom in 1 do not deviate appreciably
from the ideal values expected for a trigonal-bipyramidal
geometry. Similarly, the O–P–O angles around the phos-
phorus atom of the dipp ligand do not vary significantly
from the tetrahedral angles.
Molecular Structure of [Me2Sn(µ3-dipp)]n (1)
Colorless single crystals of 1 were obtained directly from
the reaction mixture after 3 d by slow evaporation of the
solvent from the reaction mixture. The compound crys-
tallizes in the monoclinic I2/a space group. The tin atom in
1 is five-coordinate and is surrounded by two methyl groups
and three phosphate oxygen atoms in a trigonal-bipyrami-
dal geometry (Figure 1). The dipp ligand bridges three dif-
ferent tin atoms through its three oxygen atoms in a 3.111
mode (Harris notation).[19] The three phosphate oxygen
atoms around the metal ion originate from three different
dipp ligands and occupy the two axial and one equatorial
positions of the trigonal-bipyramidal polyhedron to form a
Molecular Structure of [Me2Sn(µ-dmpp-H)2]n·nH2O (2)
Colorless single crystals of 2 were obtained from a meth-
anol/ethanol solution by slow evaporation of the solvent at
¯
room temperature. Compound 2 crystallizes in triclinic P1
space group. The unit cell contains the repeating units of
two crystallographically independent tin phosphate poly-
mers. The coordination environment around one of the tin
atoms is shown in Figure 3, and the structure of one of the
polymeric chains is shown in Figure 4. Every tin atom in
the polymeric chain is surrounded by two methyl groups
and four oxygen atoms from four different bridging phos-
phate ligands. In other words, the adjacent dimethyltin units
in the chain are linked by the POO– moiety of two bridging
dmpp-H ligands. This results in the formation of Sn2O4P2
rings that are connected to each other at the tin centers.
The individual eight-membered rings as well as the poly-
meric chain as a whole are planar, unlike that observed for
1. The structure of 2 resembles that of the di-tert-butyl
phosphate copper polymer [Cu(dtbp)2]n, reported by us a
few years ago.[20] The major difference between the struc-
ture of 2 and [Cu(dtbp)2]n is the presence of an unionized
P–OH group in 2.
While dipp is tridentate in 1, the dmpp-H ligand in 2 acts
only as a bidentate ligand. Because of this, the P–O(M)
bonds [P1–O2 1.483(4), P1–O3 1.502(4), P2–O6 1.521(4),
P2–O7 1.507(4) Å] around each phosphorus atom are
shorter than the other P–O distances. The P–O(C) bond
lengths are the longest [P1–O1 1.589(4), P2–O5 1.584(4) Å],
while the P–O(H) distances are of intermediate length [P1–
O4 1.559(4), P2–O8 1.562(4) Å]. All the Sn–O distances in
the molecule are very similar. While the tin atoms exhibit
almost regular octahedral coordination geometries, the
Figure 1. A section of polymeric 1 that illustrates the presence of
eight-membered Sn2O4P2 rings and the coordination geometry
around the tin atom. Selected bond lengths [Å] and angles [°]: Sn1–
O2 2.154(6), Sn1–O3 2.022(7), Sn1–O4 2.153(6), P1–O1 1.614(8),
P1–O2 1.495(7), P1–O3 1.512(6), P1–O4 1.508(6); O3–Sn1–O4
86.9(2), O3–Sn1–O2 90.0(2), O4–Sn1–O2 176.3(2).
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Organotin Compounds Derived from Bulky Monoaryl Phosphates
donor, while in the other two it acts as the acceptor. Since
the H-bonding interactions exist between any two adjacent
polymeric chains in the lattice, there is a continuum of H-
bonds in the crystal, which explains the complete insolubil-
ity of 2 in most solvents.
Figure 5. Lattice water aided interchain hydrogen bonding in 2.
The phosphate groups are shown as gray polyhedra, while the tin
centers are in the black polyhedra.
Figure 3. A segment of one of the polymeric chains in 2 that shows
the coordination environment around the tin atom. Selected bond
lengths [Å] and angles [°]: Sn1–O2 2.215(4), Sn1–O3 2.250(4), Sn1–
O6 2.236(4), Sn1–O7 2.197(4), P1–O1 1.589(4), P1–O2 1.483(4),
P1–O3 1.502(4), P1–O4 1.559(5), P2–O5 1.584(4), P2–O6 1.521(4),
P2–O7 1.507(4), P2–O8 1.562(5); C1–Sn1–O7 88.1(2), C2–Sn1–O7
92.6(2), C1–Sn1–O2 91.7(2), C2–Sn1–O2 87.6(2), C1–Sn1–O6
87.9(2), C2–Sn1–O6 92.1(2), O7–Sn1–O6 94.2(2), O2–Sn1–O6
86.2(2), C1–Sn1–O3 91.7(2), C2–Sn1–O3 88.4(2), O7–Sn1–O3
85.6(2), O2–Sn1–O3 94.0(2), O7–Sn1–O2 179.6(2), O6–Sn1–O3
179.5(2). The repeating unit based on Sn2 has similar bond lengths
and angles.
Synthesis and Characterization of [nBu2Sn(µ-dipp-H)-
(dipp-H)]2 (4)
The reaction between dibutyltin oxide (nBu2SnO) and
dipp-H2 in a 1:1 molar ratio takes place in acetone at 25 °C
over a period of 2 d and results in the precipitation of a
white powder. Crystallization of this white precipitate in
toluene at room temperature yields colorless crystals of
[nBu2Sn(µ-dipp-H)(dipp-H)]2 (4) (Scheme 2). As in the case
of the formation of 3 described above, the above reaction
does not produce the 1:1 product for any of the stoichio-
metric conditions employed during the synthesis. Hence,
higher yields of 4 were obtained by repeating the reaction
in a 1:2 molar ratio of the two reactants.
The composition of 4 could readily be inferred from the
analytical data obtained for its single crystals. Unlike com-
pounds 1–3, the n-butyl derivative 4 is soluble in most or-
ganic solvents and hence could be characterized in solution.
The enhanced solubility of 4 could be attributable to the
presence of two n-butyl groups on each tin atom as well as
the formation of a smaller aggregate because of steric
reasons (vide infra).
Figure 4. Polymeric chain formation in 2.
The infrared spectrum of 4 shows a strong and broad
absorption band at 2320 cm–1 arising from the presence of
phosphorus centers remain largely tetrahedral. The Sn–O– unreacted P–OH groups on the dipp ligand. The ESI mass
P angle is quite large (av. Sn–O–P 138.6°). spectrum of 4 recorded in a toluene/acetonitrile mixture
This unionized P–OH group in 2 acts the source of exten- shows the base peak at m/z = 979.3 that corresponds to the
1
sive interchain hydrogen bonding between the polymeric [M – 2dipp]+ fragment. The integrated H NMR spectral
chains, which has been further aided by the presence of lat- intensities of the n-butyl and the phosphate aryl groups sug-
tice water molecules residing between the chains (Figure 5). gest the presence of two dipp-H ligands per tin atom. The
Although there is no H-bonding between the water mole- resonance appearing at δ = 5.20 ppm is due to the P–OH
cules, which themselves are arranged in the form of a chain protons. The 31P NMR spectrum shows two very broad sin-
between the two tin phosphate polymeric chains, each water glets at –7.0 and –12.1 ppm. Because of the very broad na-
molecule is involved in the formation of four O–H···O hy- ture of the signals, the expected 117/119Sn satellite peaks
drogen bonds. In two of these H-bonds, water acts as a could not be observed. Moreover, since the X-ray diffrac-
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Scheme 2. Synthesis of dimeric and tetrameric organotin phosphates 4 and 5.
tion studies suggest that the molecule should exhibit a three
line spectrum (with a 2:1:1 ratio for dipp-H, dipp-H2 and
dipp ligands, respectively), a variable temperature 31P NMR
study was carried out in the temperature range 300–243 K.
The spectral pattern, however, remained the same. Thus, the
presence of only two 31P NMR signals over the entire tem-
perature range studied suggests that the only two types of
dipp-H phosphate ligands exist in the molecule in solution
as has been reported for the di-n-butyltin methylphos-
phonate complex by Ribot et al.[15] These observations have
further been supported by the presence of a single broad
multiplet centered at –258.7 ppm in the 119Sn NMR spec-
trum of 4.
Figure 6. Molecular structure of [nBu2Sn(dipp-H)(µ-dipp-H)]2 (4).
Selected bond lengths [Å] and angles [°]: Sn1–O5 2.027(2), Sn1–
O7 2.156(2), Sn1–O1 2.259(2), Sn2–O14 2.036(2), Sn2–O9 2.148(2),
Sn2–O13 2.178(2), P1–O1 1.483(2), P1–O2 1.532(3), P1–O3
1.538(3), P1–O4 1.571(2), P2–O7 1.498(2), P2–O6 1.516(2), P2–O5
1.539(2), P2–O8 1.587(3), P3–O10 1.497(3), P3–O9 1.499(2), P3–
O11 1.553(3), P3–O12 1.583(2), P4–O13 1.494(2), P4–O14 1.500(3),
P4–O15 1.536(3), P4–O16 1.588(3), O2–H2 0.84(6), O3–H3 0.75(4),
O7–P2(#1) 1.498(2), O8–C21 1.422(4), O11–H11 0.71(4), O14–
P4(#2) 1.500(3), O15–H15 0.63(3); O5–Sn1–O7 88.55(9), O5–Sn1–
O1 86.65(9), O7–Sn1–O1 175.09(9), O14–Sn2–O9 82.84(9), O14–
Molecular Structure of 4
Compound 4 was crystallized from toluene at room tem-
perature, and colorless single crystals were obtained after
5 d by slow evaporation of the solvent. Compound 4 crys-
¯
tallizes in the triclinic P1 space group. The asymmetric part
of the unit cell has two halves of chemically and crystallo- Sn2–O13 82.45(9), O9–Sn2–O13 164.98(9), O1–P1–O2 113.8(2),
O1–P1–O3 114.1(2), O2–P1–O3 108.2(2), O1–P1–O4 109.3(1), O2–
P1–O4 106.3(2), O3–P1–O4 104.5(1), O7(#1)–P2–O6 113.3(1),
O7(#1)–P2–O5 112.2(1), O6–P2–O5 109.9(1), O7(#1)–P2–O8
105.8(1), O6–P2–O8 109.9(1), O5–P2–O8 105.4(1), O10–P3–O9
graphically different tin phosphate molecules (Figure 6).
The two molecules of 4 in the unit cell are centrosymmetric
dimers based on eight-membered rings containing two five-
coordinate tin atoms and two phosphate ligands that bridge
the tin atoms. The tin atoms in both the molecules exhibit
a trigonal-bipyramidal environment. Apart from the two
butyl groups and the two bridging phosphate ligands, each
tin is surrounded by an additional terminal phosphate li-
gand.
115.0(2), O10–P3–O11 111.1(2), O9–P3–O11 111.5(2), O10–P3–
O12 107.4(1), O9–P3–O12 108.0(1), O11–P3–O12 103.0(2), O13–
P4–O14(#2) 117.7(1), O13–P4–O15 109.9(2), O14(#2)–P4–O15
109.9(2), O13–P4–O16 108.3(1), O14(#2)–P4–O16 104.3(1), O15–
P4–O16 107.0(2), P1–O1–Sn1 149.9(2), P2–O5–Sn1 125.0(1),
P2(#1)–O7–Sn1 143.0(2), P3–O9–Sn2 138.3(2), P4–O13–Sn2
155.4(2), P4(#2)–O14–Sn2 149.8 (2).
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Organotin Compounds Derived from Bulky Monoaryl Phosphates
The two independent molecules of 4 in the unit cell, how- Synthesis and Characterization of [(nBuSn)4(O)2(dipp-H)8] (5)
ever, differ from each other in terms of the number of un-
dissociated protons on the phosphate ligands. For example,
the bridging phosphate ligands in molecule A (Sn1) have
lost both the acidic protons (dipp), while the terminal phos-
phate ligand is completely undissociated (dipp-H2). On the
other hand, in molecule B (Sn2), the bridging as well as
the terminal phosphate ligands are monodissociated (dipp-
The reaction of n-butylstannoic acid with dipp-H2 was
carried out by using a procedure that is very similar to the
synthesis of 4. The reaction of 2 equiv:dipp-H2 with n-bu-
tylstannoic acid in acetone at room temperature over a few
days produces [(nBuSn)4(O)2(dipp-H)8] (5). Like 4, com-
pound 5 is also soluble in common organic solvents. The
elemental analysis of 5 indicates the presence of two dipp
ligands per [nBuSn] unit (Scheme 2).
H).[21] This can be readily seen from the differences in the
P2–O6 [1.516(2) Å] and P4–O16 distances [1.588(3) Å].
Thus, the composition of 4 in the crystal can best be de-
scribed as [{nBu2Sn(µ-dipp)(dipp-H2)}2{nBu2Sn(µ-dipp-
H)(dipp-H)}2], although in solution there are no totally un-
dissociated or doubly dissociated phosphate ligands, as evi-
denced by variable-temperature 31P NMR spectroscopy. A
closer look at the {nBu2Sn(µ-dipp)(dipp-H2)}2 part of 4 re-
veals that one of the P–OH groups [O2] of the terminal
ligand is pointed towards the phosphoryl group of the
bridging ligand [O6], which facilitates the formation of a
strong P–O–H···O=P intramolecular hydrogen bond. This
proton, sandwiched between the P–O groups, prefers the
terminal oxygen atom in the solid state, while it stays on
the bridging phosphate oxygen atom in solution, thus pro-
ducing only one set of 31P NMR signals.
The IR spectrum of 5 shows absorption bands at 1176
and 1150 cm–1 corresponding to presence of Sn–O–P sym-
metric and asymmetric stretching frequencies. The broad
absorption peak observed at 2329 cm–1 is due to the pres-
ence of unionized P–OH groups on the phosphate ligands.
The absorption bands at 2964 and 2931 cm–1 are due to
aliphatic C–H vibrations. In the ESI mass spectrum of com-
pound 5, the peak observed at m/z = 2431.5 corresponds
to the loss of one dipp ligand, one n-butyl group, and
two –OH ligands from the molecular ion. Further loss of
the additional dipp ligand produces a peak at m/z = 2192.2.
The base peak at m/z = 1551.2 is for the [M – 4dipp –
3nBu – 2OH]+ fragment.
1
In the H NMR spectrum, compound 5 shows a triplet
at around 7.23–7.30 ppm and a doublet at around 7.15–
7.20 ppm for the aryl protons. The broad peak centred at δ
= 4.75 ppm corresponds to the resonance of the P–OH pro-
tons. As expected, methine protons show a multiplet in the
region 3.30–3.60 ppm, while the methyl of the isopropyl
groups presents a doublet in the region 1.33–1.41 ppm.
Multiplets are observed in the appropriate region for the
methyl and methylene protons of the n-butyl groups with
expected intensities. In the 31P NMR spectrum, there are
two singlet resonances at –10.56 and –19.26 ppm with the
117/119Sn satellites (2JSnP = 283.2 and 226.2 Hz, respec-
tively). The spectral pattern and the chemical shift values
are similar to those reported for [(nBuSn)4(O)2(tbp-H)8][11]
or [(PhCH2Sn)4(O)2(tbp-H)8][14] (tbp-H2 = tert-butylphos-
phonic acid), which suggests that 5 will also have a similar
molecular structure. Thus, the observed 31P NMR spectral
pattern of 5 is consistent with the molecular formula
[(nBuSn)4(O)2(dipp-H)8]n, in which four dipp-H ligands are
in one environment, while the remaining four dipp-H li-
gands are in a different environment, at least in solution.
The 13C NMR spectrum further confirms this solution
structure for 5 with the presence of only thirteen signals in
the expected regions. The 119Sn NMR spectrum of 5 shows
a single multiplet centered at –641.5 ppm, which arises from
the four chemically equivalent tin atoms in the molecule
that are coupled to two different types of phosphorus cen-
ters.
Apart from the above-mentioned O2–H···O6 intramolec-
ular hydrogen bond between the terminal and bridging
phosphate ligands in molecule A [Sn1], there are additional
intermolecular O–H···O hydrogen bonds that results in the
formation of the H-bonded polymeric chain, as shown in
Figure 7 (bottom). In molecule B, there are no intramolecu-
lar hydrogen bonds, but intermolecular hydrogen bonds are
exclusively formed, as shown in Figure 7 (top), to produce
a ladder-type structure. This structure contains a covalent
eight-membered ring, a hydrogen-bonded eight-membered
ring, and a hydrogen-bonded six-membered ring as the re-
peating unit.
Molecular Structure of 5
Compound 5 was crystallized from CH2Cl2/toluene at
5 °C. The colorless single crystals obtained after 5 d were
found to crystallize in the monoclinic C2/c space group. The
molecule is centrosymmetric and contains four tin atoms
and eight phosphate molecules. The core structure of 5 es-
Figure 7. Hydrogen-bonding polymeric chains of [{nBu2Sn(µ-
dipp)(dipp-H2)}2{nBu2Sn(µ-dipp-H)(dipp-H)}2] (4). The H-bond-
ing pattern observed for the bottom (Sn1) and top chains (Sn2)
are different. (Phenyl hydrogen atoms, and n-butyl and isopropyl
hydrogen atoms are removed for clarity).
Eur. J. Inorg. Chem. 2008, 1508–1517
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1513

R. Murugavel, S. Shanmugan, S. Kuppuswamy
FULL PAPER
sentially resembles the tert-butylphosphonate tin clusters the solid state, has the structure [nBu4Sn4(µ-OH)2(µ-dipp-
[(nBuSn)4(O)2(tbp-H)8][11] or [(PhCH2Sn)4(O)2(tbp-H)8][14] H)6(µ-dipp)2], while in solution it retains the structure
(Figure 8). However, the overall solid-state structure of 5 is [nBu4Sn4(µ-O)2(µ-dipp-H)8].[22]
clearly different from its solution structure or from the
Since the X-ray diffraction studies suggest the presence
solid-state structures reported for [(nBuSn)4(O)2(tbp-H)8][11] of two totally dissociated dipp ligands, the 31P NMR spec-
or [(PhCH2Sn)4(O)2(tbp-H)8].[14] While the phosphonate trum of 5 was one again investigated in the temperature
clusters are built around two RSn–O–SnR units that are range 300–243 K in order to see whether the solid-state
held together by eight tbp-H phosphonate ligands,[11,14] this structure is also frozen in solution at lower temperature.
unit in 5 is a RSn–OH–SnR group. Because of the presence The results of this investigation, however, clearly show no
of an OH– group instead of an O2– anion, two out of the spectral change in the entire temperature range. It appears
total eight phosphate ligands are doubly ionized. Thus, the that the transformation of one form to the other seems to
cluster 5 contains two dipp and six dipp-H ligands. The P1 be a facile process when compound 5 is dissolved in CDCl3,
and P4 (or P1Ј and P4Ј) phosphate groups hold the tin which is aided by the presence of extensive intramolecular
atoms within the Sn–OH–Sn units together, while the two hydrogen bonding between the P–OH groups and other po-
dipp ligands (P2 and P2Ј) and two dipp-H ligands (P3 and tential hydrogen-bond donors and acceptors within the
P3Ј) bridge the two Sn–OH–Sn units across to eventually molecule (Figure 9).
result in a cubane-like structure.
Figure 9. Core structure of 5 that shows six phosphate monoanions
and two phosphate dianions. The hydrogen bonds formed by the
undissociated hydrogen atoms are shown as broken lines.
Figure 8. Molecular structure of 5. Selected bond lengths [Å] and
angles [°]: Sn1–O3 2.070(2), Sn1–O7 2.082(2), Sn1–O15 2.097(2),
Thermal Studies
Sn1–O11 2.107(2), Sn1–O1 2.109(2), Sn2–O16 2.086(2), Sn2–O4
2.090(2), Sn2–O8 2.092(2), Sn2–O1 2.103(2), Sn2–O12 2.118(2),
P1–O3 1.501(2), P1–O4 1.509(2), P1–O5 1.543(2), P1–O2 1.566(2),
P2–O8 1.505(2), P2–O7 1.511(2), P2–O9 1.527(2), P2–O6 1.580(2),
P3–O12 1.499(2), P3–O11 1.511(2), P3–O13 1.540(2), P3–O10
1.582(2), P4–O15 1.501(2), P4–O16 1.502(2), P4–O17 1.535(3), P4–
O14 1.570(2); O3–Sn1–O7 164.77(8), O3–Sn1–O15 89.75(9), O7–
Sn1–O15 92.94(9), O3–Sn1–O11 87.10(9), O7–Sn1–O11 87.55(8),
O15–Sn1–O11 169.46(8), O3–Sn1–O1 81.83(9), O7–Sn1–O1
83.54(9), O15–Sn1–O1 84.19(8), O11–Sn1–O1 85.40(8), O16–Sn2–
O4 90.20(9), O16–Sn2–O8 168.53(9), O4–Sn2–O8 88.70(9), O16–
Sn2–O1 85.16(9), O4–Sn2–O1 83.53(9), O8–Sn2–O1 83.37(8), O16–
Sn2–O12 90.81(9), O4–Sn2–O12 161.36(8), O8–Sn2–O12 86.63(8),
O1–Sn2–O12 78.00(9).
The thermal analysis (TGA) of 1 showed that the sample
is stable on heating up to 350 °C. Subsequent heating in the
region 350–500 °C leads to a major weight loss (59%),
which corresponds to the loss of both methyl and 2,6-di-
isopropylphenyl groups. The residue left at this point
roughly corresponds to the formation of Sn2P2O7 (≈ 35%).
In order to confirm the formation of Sn2P2O7, a bulk them-
olysis of 1 at 500 °C was carried out for 4 h. The final resi-
due obtained was examined by PXRD and was indeed
found to be Sn2P2O7.[23]
In the case of 2, the TGA studies showed that the loss
of organic moiety takes place very slowly in the temperature
Apart from the fact that there are no hydrogen atoms range 300–500 °C, probably because of the presence of two
found near O9, the P2–O9 distance is also considerably phosphate ligands per metal atom. The weight of the resi-
shorter [1.527(2) Å] than the P1–O5, P3–O13, and P4–O17 due left after condensation of all free –OH groups corre-
distances [1.543(2), 1.540(3), 1.535(3) Å, respectively]. Fur- sponds to the formation of SnP2O7 in this case. Compound
ther, the hydrogen atom on O1 can easily be located on the 3 undergoes two weight losses; the initial loss at around
difference Fourier map, and its inclusion in the refinement 100 °C corresponds to the removal of the lattice water mole-
results in an excellent convergence for the positional and cule. Subsequently, between 200 and 400 °C, the organic
thermal parameters. Hence, it can be concluded that 5, in substituents are lost, and the final decomposition product
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Eur. J. Inorg. Chem. 2008, 1508–1517

Organotin Compounds Derived from Bulky Monoaryl Phosphates
tin compounds. Commercially available starting materials such as
dimethyltin dichloride (Aldrich), diphenyltin dichloride (Aldrich),
n-butylstannoic acid(Aldrich), di-n-butyltin oxide (Aldrich) were
used as received. The 1H (Me4Si internal standard), 31P (85%
H3PO4 external standard), and 119Sn (Ph4Sn external standard)
NMR spectra were recorded on a Varian VXR 400S spectrometer.
Infrared spectra were obtained from a Nicolet Impact-400 FT-IR
spectrometer. Microanalyses were performed on a Thermo Finni-
gan (FLASH EA 1112) or a Carlo Eraba 1106 microanalyzer.
Thermogravimetric analysis was carried out at IIT, Bombay, on a
that remains just above 500 °C is formulated as SnP2O7. An
independent thermolysis of the bulk samples of 2 and 3 at
500 °C for 4 h followed by PXRD examination revealed
that the final decomposition product indeed is SnP2O7.[24]
The final decomposition products obtained at ca. 500 °C
for the above thermolysis studies were found to be phase
pure. However, if the decomposition was continued beyond
800 °C, P2O5 is lost, which leads to the formation of tin
oxide(s), as was observed for several metal phosphates pre-
pared by us using molecular precursor routes.[25] The for- Perkin–Elmer thermal analysis system, under a stream of nitrogen
gas. Powder X-ray diffraction data were obtained with a Philips
XЈPert Pro X-ray diffraction system by using monochromated Cu-
Kα1 radiation (λ = 1.5406 Å).
mation of Sn2P2O7 in the case of 1 and SnP2O7 in the case
of 2 clearly demonstrate the importance of designing suit-
able precursors with an appropriate metal/phosphate ligand
ratio in order to obtain phase-pure ceramic phosphates. In
the thermolysis of both 4 and 5, which also contain a Sn/P
ratio of 1:2, 4 and 5 neatly decompose to yield SnP2O7 as
in the case of 2 and 3.
Synthesis of 1: A solution of dipp-H2 (258 mg, 1 mmol) in ethanol
(25 mL) was added to a solution of Me2SnCl2 (220 mg, 1 mmol) in
ethanol (25 mL). The reaction mixture was stirred for 6 h. The
solution was filtered and left to crystallize at room temperature.
Colorless crystals of 1 were formed from this solution after 3 d.
Yield: 366 mg (90% based on Me2SnCl2). M.p.: Ͼ250 °C.
C14H23O4PSn (Mr = 404.98): calcd. C 41.52, H 5.72; found C 41.69,
Conclusions
H 5.22. IR (KBr): ν = 3431 (br.), 3057 (w), 3021 (w), 2967 (m),
˜
We have shown that a variety of oligomeric and poly-
meric structures of tin phosphates can be synthesized by a
proper choice of organotin precursor and organophosphate
ester as the reactant. When the organic substituent on the
tin atom is a methyl group, invariably a polymeric material
(compounds 1–3) is obtained as the product. The nature of
polymer formed seems to further depend on the organic
substituent on the phosphate oxygen atom. While the 2,6-
diisoprpyl group on the phosphorus atom prefers the for-
mation of a 1:1 polymer 1 with a ladder structure, the pres-
ence of the smaller 2,6-dimethylphenyl substituent invaria-
bly results in the formation of a 1:2 polymer 2. The change
in the organic substituent on the tin atom to the (bulkier)
n-butyl group completely impedes polymer formation, and
in this case only a dimeric phosphate that contains both
bridging and terminal phosphate ligands (compound 4) can
be obtained. Decreasing the organic content on tin, by
choosing nBuSn(O)(OH) as the precursor, leads to the iso-
lation of a 3D cage structure 5 and not to a ring or poly-
meric structure. In the cases in which it is possible to obtain
soluble compounds, it has been shown that the solution
structures differ somewhat from the solid-state structures.
These changes often involve the movement of acidic pro-
tons within the molecule, often aided by strong intramolec-
ular hydrogen bonds. This clearly suggests that it would be
possible to obtain more structural types of tin phosphates
by a careful variation of the starting materials. Finally, the
different tin/phosphorus ratios found in the compounds re-
ported herein prompted the investigation of their utilization
as precursors for tin phosphate ceramic materials. Because
of the 1:1 ratio of Sn/P in 1, the thermolysis leads to the
isolation of Sn2P2O7, while the thermolysis of compounds
2–5 proceeds to form SnP2O7.
2929 (m), 2868 (w), 1639 (w), 1466 (w), 1445 (vs), 1405 (w), 1361
(w), 1254 (w), 1200 (w), 1192 (w), 1144 (w), 1088 (w), 1046 (w),
1031 (w), 926 (s), 881 (w), 796 (w), 772 (w), 750 (w), 666 (s), 601
(w), 581 (w), 539 (w) cm–1. TGA: temperature range (weight loss):
350–450 °C (59%).
Synthesis of 2: A solution of dmpp-H2 (202 mg, 1 mmol) in meth-
anol (25 mL) was added to a solution of Me2SnCl2 (220 mg,
1 mmol) in methanol (25 mL). The reaction mixture was stirred for
6 h. The solution was filtered; ethanol (10 mL) was added, and the
solution was left to crystallize at room temperature. Colorless crys-
tals of 2 were formed from this solution after 5 d. Yield: 265 mg
(47% based on Me2SnCl2). M.p.: Ͼ250 °C. C18H28O9P2Sn (Mr =
569.04): calcd. C 37.99, H 4.96; found C 37.84, H 4.72. IR (KBr):
ν = 3432 (br.), 3021 (w), 2956 (w), 2926 (m), 2846 (w), 1621 (br.),
˜
1476 (s), 1269 (w), 1204 (w), 1179 (w), 1144 (vs), 1112 (vs), 1011
(vs), 942 (w), 917 (s), 781 (vs), 738 (w), 660 (w), 620 (w), 586 (w),
525 (w) cm–1. TGA: temperature range (weight loss): 155–252 (1%),
252–411 (34%), 411–604 °C (12%).
Synthesis of 3: A solution of dipp-H2 (516 mg, 2 mmol) in ethanol
(25 mL) was added to a solution of Me2SnCl2 (220 mg, 1 mmol) in
ethanol (25 mL). The reaction mixture was stirred for 6 h. The
solution was filtered and left to crystallize at room temperature. A
colorless amorphous solid precipitated from this solution after 3 d.
Yield: 238 mg (35% based on Me2SnCl2). M.p.: Ͼ250 °C.
C26H44P2O8Sn (Mr = 681.29): C 45.84, H 6.51; found C 46.39, H
6.18. IR (KBr): ν = 3618 (w), 3430 (br.), 3060 (w), 2967 (s), 2934
˜
(w), 2873 (w), 2300 (br.), 1934 (w), 1617 (br.), 1462 (w), 1437 (m),
1386 (w), 1365 (w), 1335 (w), 1298 (w), 1256 (w), 1209 (w) 1173(s),
1096 (w), 1073 (m), 1049 (s), 995 (vs), 968 (s), 930 (w), 916 (w),
798 (w), 775 (w), 751 (w), 658 (w), 599 (w), 522 (m), 539 (w) cm–1.
TGA: temperature range (weight loss): 70–120 (3%), 120–500 °C
(62%).
Synthesis of 4: A solution of dipp-H2 (516 mg, 2 mmol) in acetone
(25 mL) was added to a solution of nBu2SnO (249 mg, 1 mmol) in
acetone (25 mL). The reaction mixture was stirred for 2 h. The
solution was filtered. The precipitate obtained from the filtrate af-
ter 2 d was dissolved in toluene, and the solution was left to crys-
tallize at room temperature. Colorless crystals of 4 were formed
from this solution after 5 d. Yield: 318 mg (43% based on
nBu2SnO). M.p.: 193–195 °C. C64H108O16P4Sn2 (Mr = 1496.46):
Experimental Section
General: All reactions were carried out in the presence of air in a
beaker; however, precautions were taken to avoid contact of all
Eur. J. Inorg. Chem. 2008, 1508–1517
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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1515

R. Murugavel, S. Shanmugan, S. Kuppuswamy
FULL PAPER
Table 1. Crystal data for 1, 2, 4, and 5.
1
2
4
5
Formula
Fw
T [K]
C14H23O4PSn
404.98
150(2)
C18H28O9P2Sn
569.04
150(2)
C64H108O16P4Sn2
1494.76
150(2)
C112H180O34P8Sn4
2793.08
150(2)
Wavelength [Å]
Crystal system
Space group
a [Å]
b [Å]
c [Å]
0.71073
monoclinic
I2/a
11.2029(10)
25.342(2)
13.1541(12)
90
110.209(9)
90
3504.6(5)
8
0.71073
0.71073
0.71073
monoclinic
C2/c
28.6248(5)
21.9667(4)
21.2309(3)
90
95.142(1)
90
13296.1(4)
4
triclinic
triclinic
¯
¯
P1
P1
10.026(2)
15.4266(17)
16.1250(18)
66.927(2)
89.987(6)
80.720(5)
2259.1(6)
4
10.4259(2)
14.5000(4)
24.5511(6)
94.583(2)
91.475(2)
97.696(2)
3663.84(15)
2
α [°]
β [°]
γ [°]
V [Å3]
Z
Dcalcd. [Mgm–3]
Abs. coeff. [mm–1]
F(000)
1.535
1.558
1632
1.673
1.319
1152
1.355
0.829
1560
1.395
0.909
5776
Crystal size [mm]
θ range [°]
0.40ϫ0.25ϫ0.15
3.09–25.00
3085 (0.1625)
99.6
0/187
0.966
0.33ϫ0.26ϫ0.21
3.12–25.00
7896 (0.0216)
99.0
0/565
0.915
0.33ϫ0.26ϫ0.21
2.97–25.00
12763 (0.0405)
98.8
0/791
1.049
0.34ϫ0.31ϫ0.28
2.95–25.00
11676 (0.0367)
99.7
42/775
1.109
Data (Rint
)
Completeness to 2θ [%]
Restraints/parameters
GoF on F2
R1 [IϾ2σ(I)]
wR2 [IϾ2σ(I)]
0.0679
0.1141
0.0209
0.0543
0.0363
0.0736
0.0323
0.0620
R1 (all data)
0.1555
0.0704
0.0629
0.0481
calcd. C 51.42, H 7.28; found C 50.95, H 7.76. IR (KBr): ν = 3417
H) ppm. 13C NMR (CDCl3, 101 MHz): δ = 146.9 (s, C, Ar-C1),
˜
(br.), 3065 (w), 2965 (vs), 2923 (m), 2870 (m), 2320 (br.), 1931 (br.),
140.8 (s, C, Ar-C2), 123.9 (s, C, Ar-C3), 140.5 (s, C, Ar-C4), 146.5
1860 (w), 1639 (br.), 1464 (s), 1440 (m), 1383 (w), 1362 (w), 1335 (s, C, Ar-C5), 125.5 (s, C, Ar-C6), 26.2 (s, C, iPr-CA), 26.9 (s, C,
(m), 1257 (s), 1176 (s), 1135 (s), 1111 (w), 1046 (w), 992 (s), 965 iPr-CB), 26.3 (s, C, iPr-CC), 28.1 (s, C, nBu-Ca), 23.5 (s, C, nBu-
(m), 882 (w), 798 (w), 772 (s), 750 (m), 716 (w), 664 (w), 622 (w), Cb), 23.3 (s, C, nBu-Cc), 13.7 (s, C, nBu-Cd) ppm. 31P NMR
595 (w), 541 (w), 526 (w), 508 (w) cm–1. 1H NMR (C6D6, (CDCl3, 162 MHz): δ = –10.6 (2JSnP = 283.2 Hz), –19.3 (2JSnP
=
3
400 MHz): δ = 0.8–1.0 (s, 3 H, nBu-CH3), 1.12–1.50 (d, JHH
=
226.2 Hz) ppm. 119Sn NMR (CDCl3): δ = –641.5 ppm. Mass spec-
6.0 Hz, 3 H, iPr-CH3), 1.2–1.5 (m, 2 H, nBu-CH2), 3.35–3.50 (m, trum (ESI = 70 eV): m/z = 2431.5 [M – dipp – Bu – 2OH]+, 2192.2
2 H, iPr-CH), 5.20–5.30 (s, 1 H, P-OH), 7.0–7.1 (s, 3 H, Ar-H)
ppm. 31P NMR (C6D6, 162 MHz): δ = –7.0, –12.1 ppm. 119Sn
NMR (C6D6): δ = –285.7 ppm. Mass spectrum (ESI = 70 eV): m/z
=979 [M–2dipp]+,749.3 [M–2dipp –SnBu2]+ and491.1[M– 3dipp–
SnBu2]+. TGA: temperature range (weight loss): 172–252 (18%),
252–415 °C (46%).
[M – 2dipp – Bu – 2OH]+ and 1551.2 [M – 4dipp – 3Bu – 2OH]+.
TGA: temperature range (weight loss):78–146 (3%), 146–265
(20%), 265–505 °C (40%).
Single-Crystal X-ray Studies: Intensity data for all four samples
were collected on a Oxford XCalibur CCD diffractometer. All cal-
culations were carried out with the programs in the WinGX mod-
ule.[26] The structure solution was achieved by direct methods in
most cases using SIR-92 as implemented in WinGX.[27] The final
refinement of the structure was carried out by using full least-
squares methods on F2 with SHELXL-97.[28] Selected crystal
data are given Table 1. CCDC-666770, -666771, -666772 and
-666773 contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Synthesis of 5: A solution of dipp-H2 (516 mg, 2 mmol) in acetone
(25 mL) was added to a solution of nBuSn(O)(OH)·xH2O (204 mg,
≈1 mmol) in acetone (25 mL). The reaction mixture was stirred for
2 h, filtered, and the clear solution was left standing on the
benchtop. The precipitate formed from this solution after 2 d was
dissolved in CH2Cl2/toluene, and the solution was left to crystallize
at room temperature. Colorless crystals of 5 were obtained after
5 d. Yield: 117 mg (33% based on dipp-H2). M.p.: 211–213 °C.
C112H180O34P8Sn4 (Mr = 2793.08): calcd. C 48.16, H 6.50; found:
C 48.66, H 7.31. IR (KBr): ν = 3538 (br.), 3423 (br.), 32089 (br.),
˜
3060 (w), 3027 (w), 2964 (vs), 2931 (s), 2871 (s), 2329 (br.), 1928
(w), 1860 (w), 1650 (br.), 1465 (w), 1439 (s), 1383 (w), 1362 (w),
1335 (m), 1257 (m), 1176 (s), 1150 (s), 1123 (w), 1108 (w), 1092
(w), 1048 (w), 1012 (w), 986 (s), 936 (w), 882 (w), 872 (w), 795 (w),
769 (w), 750 (w), 685 (w), 659 (w), 625 (w), 595 (w), 548 (w), 529
(w), 510 (w), 458 (w) cm–1. 1H NMR (CDCl3, 400 MHz): δ = 0.70–
Supporting Information (see footnote on the first page of this arti-
cle): Characterization data for compounds 1–5 is presented.
Acknowledgments
3
0.80 (t, JHH = 6.4 Hz, 3 H, nBu-CH3), 1.01–1.11 (m, 2 H, nBu-
3
CH2), 1.11–1.19 (m, 2 H, nBu-CH2), 1.33–1.41 (d, JHH = 3.2 Hz,
This work was supported by DST, New Delhi, in the form of a
3 H, iPr-CH3), 1.80–1.87 (m, 2 H, nBu-CH2), 3.30–3.60 (m, 2 H, Swarnajayanti Fellowship. S. S. thanks the CSIR, New Delhi for a
2
iPr-CH), 4.75–4.85 (t, JPH = 6.3 Hz, 1 H, P-OH), 7.15–7.20 (d,
research fellowship. We thank the Single Crystal X-ray Diffraction
National Facility at IIT-Bombay for the intensity data.
3JHH = 5.6 Hz, 2 H, Ar-H), 7.23–7.30 (t, JHH = 5.6 Hz, 1 H, Ar-
3
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© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2008, 1508–1517

Organotin Compounds Derived from Bulky Monoaryl Phosphates
[16] S.-Y. Song, J.-F. Ma, J. Yang, L.-L. Gao, Z.-M. Su, Organome-
tallics 2007, 26, 2125.
[1]
For example, see: a) , R. Murugavel, A. Voigt, M. G. Walawal-
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Received: September 24, 2007
Published Online: February 1, 2008
Eur. J. Inorg. Chem. 2008, 1508–1517
© 2008 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
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