Direct hydrolysis of hydrated organotin cations: Synthesis and structural characterization of {[n-Bu2Sn(OH2)(Phen)(O 3SC6H3-2,5-Me2)]+[2,5- Me2C6H3so3]-}...

Article abstract of DOI:10.1021/om0701625

Direct hydrolysis of hydrated organotin cations: Synthesis and structural characterization of {[n-Bu₂Sn(OH₂)(Phen)(O ₃SC₆H₃-2,5-Me₂)]⁺[2,5- Me₂C₆H₃so₃]^-} (Phen = 1,10-phenanthroline) and {[n-Bu₂Sn(μ-OH)(O₃SC ₆H₃-2,5-Me₂)]₂}_n The reaction of {[n-Bu₂Sn(OH₂)₄] ²⁺[2,5-Me₂C₆H₃SO₃] ₂} (2) with 1,10-phenanthroline affords {[nBu₂Sn(OH ₂)(Phen)(O₃SC₆H₃-2,5-Me ₂)⁺[2,5-Me₂C₆H₃SO ₃]^-} (3) by the displacement of two water molecules by the chelating phenanthroline ligand and one water molecule by a sulfonate ligand. In contrast, 2 undergoes hydrolysis on treatment with pyridine, resulting in the formation of {[n-Bu₂Sn(μ-OH)(O₃-SC₆H ₃-2,5-Me₂)]₂}_n (4). Formation of 4 also occurs in the reaction of 3 with pyridine as well as in a 1:1 reaction of [n-Bu₂SnO]_n with 2,5-Me₂C₆H ₃SO₃H·2H₂O. The molecular structure of 3 contains a six-coordinate tin with a coordination environment comprising the chelating phenanthroline ligands, two butyl substituents, one water molecule, and one sulfonate ligand. Extensive hydrogen-bonding interactions (O - H- - -O, C - H- - -O, and O- - -π) in the crystal structure result in the formation of a three-dimensional supramolecular architecture for 3. The crystal structure of 4 reveals that it is a two-dimensional coordination polymer. The basic repeat unit of the coordination polymer contains a [Sn(μ-OH)]₂ distannoxane ring. Anisobidentate coordination action of the sulfonate ligand results in the generation of 20-membered macrocycles, which are linked to each other to form the two-dimensional coordination polymer network.

Full text of DOI:10.1021/om0701625

Organometallics 2007, 26, 2833-2839
2833
Direct Hydrolysis of Hydrated Organotin Cations: Synthesis and
Structural Characterization of
{[n-Bu2Sn(OH2)(Phen)(O3SC6H3-2,5-Me2)]+[2,5-Me2C6H3SO3]-}
(Phen ) 1,10-phenanthroline) and
{[n-Bu2Sn(µ-OH)(O3SC6H3-2,5-Me2)]2}n
Vadapalli Chandrasekhar,* Puja Singh, and Kandasamy Gopal
Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016, India
ReceiVed February 22, 2007
-
The reaction of {[n-Bu2Sn(OH2)4]2+[2,5-Me2C6H3SO3 ]2} (2) with 1,10-phenanthroline affords {[n-
Bu2Sn(OH2)(Phen)(O3SC6H3-2,5-Me2)]+[2,5-Me2C6H3SO3]-} (3) by the displacement of two water
molecules by the chelating phenanthroline ligand and one water molecule by a sulfonate ligand. In contrast,
2 undergoes hydrolysis on treatment with pyridine, resulting in the formation of {[n-Bu2Sn(µ-OH)(O3-
SC6H3-2,5-Me2)]2}n (4). Formation of 4 also occurs in the reaction of 3 with pyridine as well as in a 1:1
reaction of [n-Bu2SnO]n with 2,5-Me2C6H3SO3H‚2H2O. The molecular structure of 3 contains a six-
coordinate tin with a coordination environment comprising the chelating phenanthroline ligands, two
butyl substituents, one water molecule, and one sulfonate ligand. Extensive hydrogen-bonding interactions
(O-H- - -O, C-H- - -O, and O- - -π) in the crystal structure result in the formation of a three-dimensional
supramolecular architecture for 3. The crystal structure of 4 reveals that it is a two-dimensional coordination
polymer. The basic repeat unit of the coordination polymer contains a [Sn(µ-OH)]2 distannoxane ring.
Anisobidentate coordination action of the sulfonate ligand results in the generation of 20-membered
macrocycles, which are linked to each other to form the two-dimensional coordination polymer network.
Introduction
Organotin oxides, hydroxides, and oxide-hydroxides are the
hydrolysis products of organotin halides and serve as important
precursors for the preparation of a large variety of organostan-
noxane assemblies.1 Unlike in the case of organosilicon
compounds, the hydrolysis of organotin halides has been
speculated to occur through the intermediacy of hydrated
organotin cations such as [R2Sn(OH2)4]2+ and analogous mono-
or triorgano compounds.2 Our recent report on synthesis and
structural characterization of {[n-Bu2Sn(OH2)4]2+[2,5-Me2C6H3-
SO3-]2} (2)3a and {[n-Bu2Sn(OH2)3-[µ-L]-n-Bu2Sn(OH2)3]2+
-
[L]2-} (L ) 1,5-C6H10(SO3-)2)3b lends credence to the existence
of hydrated organotin cations. Prior to our work only one such
example, viz., {[Me2Sn(OH2)4]2+[X-]2} (X- ) 1,1,3,3-tetraoxo-
1,3,2-benzodithiazide), was known that was structurally
characterized.4a Subsequently, compounds such as {[R2Sn(OH2)2
(OPPh3)2]2+[CF3SO3-]2} (R ) Me, n-Bu) were synthesized and
Figure 1. Molecular structure of 3 shown at the 50% ellipsoidal
probability level. One of the sulfonate anions is bound to tin, while
the other is involved in a O-H- - -O hydrogen bonding with the
coordinated water proton. All the hydrogen atoms (except those of
the coordinated water) have been removed for the sake of clarity.
characterized.4b The availability of hydrated organotin cations
gives an opportunity to examine if indeed such compounds can
serve as precursors for direct hydrolysis to afford products
containing Sn-OH or Sn-O bonds. In this context it may be
mentioned that the four-membered distannoxane rings [Sn2-
(OH)2] and [Sn2O2] containing bridging hydroxide and oxide
ligands, respectively, are ubiquitous building blocks of orga-
nostannoxanes.1 But in all cases such building blocks are formed
in situ in reactions involving organotin oxides, hydroxides, or
* To whom correspondence should be addressed. E-mail: vc@iitk.ac.in.
Phone: (+91) 512-259-7259. Fax: (+91) 521-259-0007 / 7436.
(1) (a) Chandrasekhar, V.; Nagendran, S.; Baskar, V. Coord. Chem. ReV.
2002, 235, 1. (b) Chandrasekhar, V.; Gopal, K.; Sasikumar, P.; Thirumoorthi,
R. Coord. Chem. ReV. 2005, 249, 1745.
(2) (a) Rochow, E. G.; Seyferth, D. J. Am. Chem. Soc. 1953, 75, 2877.
(b) Tobias, R. S.; Ogrins, I.; Nevett, B. A. Inorg. Chem. 1966, 5, 2052,
and references therein. (c) Beckmann, J. D.; Henn, M.; Jurkschat, K.;
Schu¨rmann, M.; Dakternieks, D.; Duthie, A. Organometallics 2002, 21,
192.
(3) (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, 22,
3342.
(4) (a) Hippel, I.; Jones, P. G.; Blaschette, A. J. Organomet. Chem. 1993,
448, 63. (b) Beckmann, J.; Dakternieks, D.; Duthie, A.; Mitchell, C. Dalton
Trans. 2003, 3258.
10.1021/om0701625 CCC: $37.00 © 2007 American Chemical Society
Publication on Web 04/19/2007

2834 Organometallics, Vol. 26, No. 11, 2007
Chandrasekhar et al.
Scheme 1. Synthesis of 2-4a
a
(i) 1:2, toluene, reflux, 8 h; (ii) 1,10-phenanthroline, toluene, 60 °C, 15 min; (iii) pyridine, toluene, 60 °C, overnight; (iv) 1:1, toluene, reflux,
8 h.
Scheme 2. Possible Formation of 4 from 2 and 3 by Reacting with Pyridine
oxide-hydroxides with protic acids.1 Herein we provide the first
example of hydrolysis of organotin cation to organotin hydrox-
ide. Accordingly we report the synthesis and characterization
of {[n-Bu2Sn(OH2)(Phen)(O3SC6H3-2,5-Me2)]+[2,5-Me2C6H3-
SO3]-} (Phen ) 1,10-phenanthroline) (3) and {[n-Bu2Sn(µ-
OH)(O3SC6H3-2,5-Me2)]2}n (4).
Scheme 3. Acetylation Reactions of 3
Results and Discussion
Synthesis. The hydrated organotin cation {[n-Bu2Sn(OH2)4]2+-
[2,5-Me2C6H3SO3-]2} (2) can be conveniently synthesized in
reasonable yields in a reaction involving [n-BuSnO]n (1) and
2,5-Me2C6H3SO3H‚2H2O in a 1:2 stoichiometry.3a We have

Direct Hydrolysis of Hydrated Organotin Cations
Organometallics, Vol. 26, No. 11, 2007 2835
compound 4
Table 1. Selected Bond Parameters for the Molecular Structure of 3 and 4
compound 3
bond distance (Å)
bond angle (deg)
bond distance (Å)
bond angle (deg)
Sn1-O1 2.273(3)
Sn1-O2 2.283(3)
Sn1-N1 2.332(3)
Sn1-N2 2.310(3)
Sn1-C29 2.115(4)
Sn1-C33 2.118(4)
S1-O2 1.491(3)
S1-O3 1.439(3)
S1-O4 1.439(3)
S1-C13 1.778(4)
S2-O5 1.449(3)
S2-O6 1.465(3)
S2-O7 1.464(3)
S2-C21 1.776(4)
O1-H101 0.877(5)
O1-H102 0.846(6)
C29-Sn1-C33 165.96(16)
O1-Sn1-O2 119.11(12)
O1-Sn1-N2 159.21(12)
O1-Sn1-N1 87.30(12)
O2-Sn1-N2 81.67(11)
O2-Sn1-N1 153.21(12)
N2-Sn1-N1 71.93(12)
Sn1-O2-S1 124.98(17)
H101-O1-H102 104.25(54)
Sn1-O4 2.058(2)
Sn1-O2 2.341(2)
Sn1-O1* 2.624(2)
Sn1-O4* 2.112(2)
Sn1-C9 2.109(3)
Sn1-C13 2.121(3)
O4-H101 0.740(4)
S1-O1 1.455(2)
S1-O2 1.474(2)
S1-O3 1.450(2)
S1-C1 1.778(3)
O4-Sn1-O1* 76.41(78)
O4-Sn1-O2 74.80(8)
O4-Sn1-O4* 69.82(11)
O1*-Sn1-O2 139.01(68)
O1*-Sn1-O4* 146.19(82)
O2-Sn1-O4* 144.56(8)
C9-Sn1-C13 143.04(11)
Sn1-O2-S1 124.85(11)
Sn1-O4-Sn1* 110.18(11)
Table 2. Hydrogen-Bonding Parameters for Compounds 3 and 4
D-H---A
D-H (Å)
H---A (Å)
D---A (Å)
D-H---A (deg)
symmetry
Compound 3
O1-H101- - -O7
O1-H102- - -O6
C6-H6- - -O3
C4-H4- - -O6
C4-H4- - -O5
C3-H3- - -O5
C19-H19C- - -O3
0.877(5)
0.846(6)
0.931(6)
0.930(4)
0.930(4)
0.929(4)
0.960(6)
1.784(5)
1.811(6)
2.471(4)
2.697(3)
2.538(3)
2.663(3)
2.419(4)
2.658(5)
2.655(5)
3.242(7)
3.550(6)
3.384(5)
3.471(6)
3.372(8)
174.24(47)
174.97(61)
140.24(37)
152.96(34)
151.45(29)
145.75(34)
171.73(36)
1+x, y, 1+z
1+x, y, 1+z
1+x, y, z
2-x, 1-y, 2-z
2-x, 1-y, 2-z
2-x, 1-y, 2-z
-1-x, -y, 1-z
Compound 4
2.731(7)
O4-H101- - -O3
0.740(4)
2.047(4)
153.96(39)
0.5+x, 0.5-y, z
shown that 2 and related hydrated organotin cations are effective
catalysts for acetylation and transacetylation reactions.5 The
lability of the water molecules of the in situ-generated dication
[R2Sn(OH2)4]2+ was examined by Beckmann and co-workers,
and the compounds {[R2Sn(OH2)2(OPPh3)2]2+[CF3SO3-]2} (R
) Me, n-Bu) were isolated by displacement of two coordinated
water molecules by two phosphine oxide ligands.4b In order to
understand the reactivity of 2, we examined its reaction with
the chelating ligand Phen. We were able to isolate the mono-
hydrate derivative {[n-Bu2Sn(OH2)(Phen)(O3SC6H3-2,5-Me2)]+-
[2,5-Me2C6H3SO3]-} (3) in appreciable yields (Scheme 1). It
is of interest to note that the formation of 3 is accomplished by
replacement of three water molecules: two by the Phen ligand
and one by a sulfonate ligand. It may be mentioned that in 2
the four water molecules that are coordinated to tin are involved
in an extensive hydrogen-bonding network with the uncoordi-
nated sulfonate ligands to generate a lamellar two-dimensional
sheet.3a Disruption of this network by removal of two water
molecules presumably causes one of the noncoordinating
sulfonate ligands of 2 to enter into the coordination sphere of
3. Because of this, the organotin cation in 3 bears a unit positive
charge. The 119Sn NMR of 3 in CDCl3 solution shows a single
resonance at -413.5 ppm, confirming the six-coordinate nature
of tin. Also, the chemical shift of 3 is consistent with the
observation of Otera and co-workers, who have noticed that
119Sn chemical shifts move upfield in the presence of chelating
ligands.6
renders the coordinated water molecules readily susceptible to
proton abstraction. It is reasonable to postulate that pyridine
abstracts a proton to afford a tin monohydroxide (2a) with the
removal of pyridinium sulfonate.7 The intermediate 2a, contain-
ing the highly nucleophilic -OH group, dimerizes readily to
afford 4, which contains the hydroxide-bridged distannoxane
core [Sn2(µ-OH)2]. Dimerization is accompanied by the simul-
taneous displacement of the remaining six water ligands at the
tin centers with a concomitant coordination action of the
sulfonate ligand (Scheme 2).
Interestingly, 4 is also generated in two other reactions. First,
the direct reaction of 1 with 2,5-Me2C6H3SO3H‚2H2O in a 1:1
stoichiometry affords 4 (Scheme 1). This observation is similar
to that of Otera and co-workers, who have reported the formation
of the dimeric organotin compound [n-Bu2Sn(µ-OH)(OH2)(O3-
SCF3)]2 in a 1:1 reaction involving 1 and CF3SO3H.8a On the
other hand, the reaction between 3 and pyridine also yielded 4,
testifying to the stability of the distannoxane, [Sn2(µ-OH)2], core.
The 119Sn NMR of 4 shows two resonances at -167.6 and
-258.8 ppm. The upfield signal observed for 4 is similar to
that observed for [n-Bu2Sn(µ-OH)(OH2)(O3SCF3)]2 (-249.7
ppm).8a We were unable to isolate any independent chemical
species that could be assigned the downfield signal at -167.6
ppm. However, it must noted that solution behavior of organotin
hydroxides is complex. Thus, the closely related compound {-
[n-Bu2Sn(µ-OH)OSO2Me]2}n showed six resonances in its
solution 119Sn NMR with chemical shifts ranging from -189.3
to -162.7 ppm.8c Further, it has been observed that [R2Sn(µ-
OH)(OSO2CF3)(H2O)]2 (R ) Et, n-Bu, n-octyl) showed chemi-
cal shifts in the range -205 to -214 ppm in solution. In
In contrast to the above, reaction of 2 with nonchelating
pyridine does not proceed by ligand replacement but involves
hydrolysis to afford {[n-Bu2Sn(µ-OH)(O3SC6H3-2,5-Me2)]2}n
(4) (Scheme 1). The possible mechanism for the hydrolysis of
2 is shown in Scheme 2. The Lewis acidity of the tin atom
(7) See Supporting Information.
(8) (a) Sakamoto, K.; Ikeda, H.; Akashi, H.; Fukuyama, T.; Orita, A.;
Otera, J. Organometallics 2000, 19, 3242. (b) Orita, A.; Xiang, J.; Sakamoto,
K.; Otera, J. J. Organomet. Chem. 2001, 624, 287. (c) Narula, S. P.; Kaur,
S.; Shankar, R.; Verma, S.; Venugopalan, P.; Sharma, S. K.; Chadha, R.
K. Inorg. Chem. 1999, 38, 4777.
(5) Chandrasekhar, V.; Boomishankar, R.; Gopal, K.; Sasikumar, P.;
Singh, P.; Steiner, A.; Zacchini, S. Eur. J. Inorg. Chem. 2006, 4129.
(6) Otera, J. J. Organomet. Chem. 1981, 221, 57.

2836 Organometallics, Vol. 26, No. 11, 2007
Chandrasekhar et al.
Figure 2. Three-dimensional supramolecular assembly of 3 formed from O-H- - -O, C-H- - -O, and O- - -π interactions. (a) View showing
part of the supramolecular assembly of 3. Bonding parameters for O- - -π interaction: O4- - -πcent 3.293(5) Å [O4- - -C6 3.948(8), O4- - -
C7 3.393(7), O4- - -C8 2.973(7), O4- - -C9 3.699(7), O4- - -C10 4.089(8), O4- - -N2 3.172(6) Å]; O4- - -πplane 3.072(6) Å with a tilt angle
of ∼24°. (b) View showing the three-dimensional supramolecular architecture along the a-axis.
addition, resonances at -140 and -170 ppm were observed.8b
The latter were assigned to a trinuclear compound that is present
in equilibrium with the main product.
In view of the interest in the catalytic activity of organotin
cations vis-a`-vis acetylation reactions,3,5,8a,b we evaluated the
role of 3 in the acetylation of cinnamyl alcohol and L-menthol
(Scheme 3). We observed that by using only 0.2 mol % of 3
acetylation went to completion (100%) in 75 min (cinnamyl
alcohol) and 50 min (L-menthol). On this basis it is possible to
conclude that 3 is as effective as other hydrated tin cations for
acetylation reactions.3a,5,8a,b
Molecular and Crystal Structure of 3. The molecular
structure of 3 shows a central tin atom (Sn1) with an octahedral
coordination environment (2N, 2C, 2O) comprising two nitrogen
atoms (N1 and N2) of the Phen ligand, two oxygen atoms from
water (O1) and sulfonate (O2) ligands, and two carbon atoms
(C29 and C33) of the two n-butyl groups arranged in a trans
geometry with respect to each other (Figure 1). The bond angles
O1-Sn1-N2, O2-Sn1-N1, and C29-Sn1-C33 are 159.21-
(12)°, 153.21(12)°, and 165.96(16)°, respectively, indicating the
distortion from an ideal octahedral geometry (Table 1). This
may be contrasted to the situation found in 2, where analogous

Direct Hydrolysis of Hydrated Organotin Cations
Organometallics, Vol. 26, No. 11, 2007 2837
bond angles involving the antipodal ligands and the central tin
average to a perfect 180°.3a The Sn1-O1 distance (involving
the coordinated water) is 2.273(3) Å and is similar to that found
in 2 (average Sn-Ow 2.271(3) Å) (Table 1). Analogous
distances found in {[R2Sn(OH2)2(OPPh3)2]2+[CF3SO3-]2} are
not too different (R ) n-Bu, 2.254(2) Å and R ) Me, 2.237(3)
Å).4b The Sn1-O2 distance (involving the sulfonate ligand) is
2.283(3) Å, which is similar to the Sn1-O1 distance (Table
1). Interestingly the Sn-O distance found in [n-Bu2Sn(µ-OH)-
(OH2)(O3SCF3)]2 is 2.622(4) Å.8a Similarly in {[n-Bu2Sn(OH2)3-
[µ-L]-n-Bu2Sn(OH2)3]2+[L]2-} (L ) 1,5-C6H10(SO3-)2) the
Sn-O distance involving the sulfonate ligand is 2.515(57) Å.3b
This indicates that in the current instance tin is bound tightly
to the sulfonate ligand. The free sulfonate counteranion of 3 is
involved in an O-H- - -O hydrogen bonding with one of the
coordinated water molecules (H102- - -O6) (Figure 1). The
hydrogen-bonding parameters are given in Table 2.
Figure 3. Repeating unit of the coordination polymer 4 shown at
the 50% ellipsoidal probability level. All the hydrogen atoms (except
that of the bridging hydroxyl group) have been removed.
The supramolecular architecture of 3 is quite interesting. In
2, the four water molecules bound to tin are involved in
extensive hydrogen bonding with the two sulfonate counteran-
ions to afford a two-dimensional lamellar network.3a On the
other hand, in 3, only one water molecule is attached to the tin
atom and only one sulfonate is present as a counteranion. This
impacts the hydrogen bonding of 3 in the following way. First
two molecules of 3 are brought together to form a centrosym-
metric dimer as a result of hydrogen bonding (O-H- - -O)
between the coordinated water and the sulfonate counteranions.
Two of the oxygen atoms (O6 and O7) of each sulfonate anion
and both the hydrogen atoms (H101 and H102) of the water
(O1) molecule are involved in this hydrogen-bonding interaction
to form a 12-membered hydrogen-bonded ring (Figure 2a). The
bond parameters involved in this interaction [O1- - -O7 2.658-
(53) Å, O1-H101- - -O7 174.24(47)°, O1- - -O6 2.655(5) Å,
and O1-H102- - -O6 174.96(61)°] indicate that the hydrogen
bonds formed are quite strong (Table 2). These parameters are
comparable to those found in 23a and in {[n-Bu2Sn(OH2)3-[µ-
L]-n-Bu2Sn(OH2)3]2+[L]2-} (L ) 1,5-C6H10(SO3-)2).3b The
hierarchical progression of the supramolecular architecture in
3 occurs first by intermolecular C-H- - -O hydrogen bonding
between the dimers to afford a polymeric tape (Figure 2a). The
hydrogen atoms involved in this interaction (H3 and H4) belong
to the phenanthroline moiety, while the oxygen atoms are
derived from the sulfonate anions (O5 and O6) (Figure 2a; Table
2). Interestingly H4 is involved in a bifurcated hydrogen bond
(with O5 and O6), while O5 is also involved in a similar
interaction (with H3 and H4). The one-dimensional tape is
further glued by an additional intermolecular C-H- - -O bond
between the oxygen atom of the bound sulfonate ligand (O3)
and a hydrogen (H6) of the phenanthroline ligand (Figure 2a;
Table 2). Interestingly, these one-dimensional tapes are inter-
connected through O- - -π interactions involving the Phen ligand
(C6-C10, N2) and the sulfonate oxygen (O4) to afford a two-
dimensional network (Figure 2a). The distance between the
oxygen atom (O4) and the centroid of the Phen ligand is 3.293-
(5) Å with a tilt angle of ∼24°. The O- - -C distances that are
involved in this interaction vary from 2.973(7) Å (O4- - -C8)
to 4.089(8) Å (O4- - -C10). These O- - -π interactions are highly
directional and belong to the class of orthogonal multipolar
interactions. The contributions of such orthogonal electrostatic
interactions between dipoles in structural chemistry and biology
have been reviewed recently.9a Very recently we have shown
that the crystal structure of Ph3SnO2CFc (Fc ) ferrocenyl)
consists of an interesting supramolecular architecture mediated
by multipolar CO2- - -π interactions.9b Finally, the two-
dimensional networks described above are further connected
through C-H- - -O interactions involving the methyl substituent
(H19C of the bound xylyl sulfonate group) and the sulfonate
oxygen (O3) to afford a three-dimensional network (Figure 2b;
Table 2).
Crystal Structure of 4. The crystal structure of 4 shows that
it is a two-dimensional coordination polymer. The repeat unit
of the polymeric network is shown in Figure 3 and consists of
a four-membered distannoxane [Sn2(µ-OH)2] unit where the tin
centers are bridged by two hydroxide ligands. Each tin atom is
six-coordinate (4O, 2C) in a distorted octahedral geometry.
Apart from the two bridging hydroxide ligands (O4 and O4*)
each tin (Sn1) also contains one sulfonate ligand (O2) and two
n-butyl substituents (C9 and C13). Another oxygen of the
sulfonate ligand (O1*) belonging to an adjacent repeat unit
completes the coordination environment. The Sn-O distances
found in the four-membered ring are nearly equal [Sn1-O4
2.112(2) Å and Sn-O4* 2.058(2) Å] (Table 1). These distances
are shorter than the Sn-O distance involving the sulfonate
ligand (short distance: Sn1-O2 2.341(2) Å; long distance:
Sn1-O1* 2.624(2) Å). The Sn-O-Sn bond angle of the four-
membered ring is much wider (Sn1-O4-Sn1* 110.18(11)°) than
the O-Sn-O (O4-Sn1-O4* 69.82(11)°) angle (Table 1). A
comparison of the bond parameters of 4 with those observed in
distannoxanes containing sulfonate ligands is as follows. In
[n-Bu2Sn(µ-OH)(OH2)(O3SCF3)]2 the two Sn-O distances of
the distannoxane ring are 2.085(3) and 2.147(3) Å, respectively,8a
while the Sn-O distance involving the sulfonate ligand in 4 is
much longer (2.622(4) Å) than found in the present instance.
In [{n-Bu2Sn(µ-OH)(O3SMe)}2]n, which also forms a two-
dimensional coordination polymer, two types of Sn-O distances
are found: 2.117(4) (average Sn-(µ-OH) distance) Å; 2.429-
(4) and 2.492(4) Å (distances involving sulfonate ligand).8c In
another related example, {[n-Bu2Sn(µ-OH)(O3SC6H2-2,4,6-
Me3)]2}n,10 the Sn-O distances within the distannoxane ring
are equal at 2.199(3) Å, while the Sn-O distance involving
the sulfonate ligand is 2.313(3) Å.
The four-membered distannoxane units in 4 are linked to each
other by an anisobidentate coordination mode of a sulfonate
ligand to afford a two-dimensional grid-like coordination
polymer network containing 20-membered Sn6S4O10 macrocycle
repeat units (Figure 4).8c Within each macrocycle the hydroxide
(9) (a) Paulini, R.; Mu¨ller, K.; Diederich, F. Angew. Chem., Int. Ed. 2005,
44, 1788. (b) Chandrasekhar, V.; Gopal, K.; Nagendran, S.; Singh, P.;
Steiner, A.; Zacchini, S.; Bickley, J. F. Chem.-Eur. J. 2005, 11, 5437.
(10) Kapoor, R.; Gupta, A.; Kapoor, P.; Venugopalan, P. J. Organomet.
Chem. 2001, 619, 157.

2838 Organometallics, Vol. 26, No. 11, 2007
Chandrasekhar et al.
Figure 4. Two-dimensional coordination polymer of 4. Representation of the two-dimensional polymer is shown in the background in the
form of dotted lines.
ligands of the [Sn(µ-OH)]2 group are involved in hydrogen
bonding (O4-H101- - -O3) with the adjacent sulfonate groups
(Figure 4; Table 2). Polymeric networks containing macrocycle
repeat units are quite scarce in organotin chemistry, although a
few examples have been structurally elucidated in recent
years.8b,c,11 In the current system each macrocycle repeat unit
of the two-dimensional coordination polymer is nearly a perfect
square, with the dimensions of each side being 8.5 Å (Figure
4). The topological arrangement of the two-dimensional poly-
meric grids is not flat, however. A side view of the polymer
reveals their wavy zigzag corrugated architecture, this being
the result of the bridging sulfonate ligands undulating alternately
above and below the interconnected macrocycle mean planes.7
The interlayer distance between two adjacent zigzag layers is
14.5 Å.7
the four-membered distannoxane ring [Sn2(OH)2] as its building
unit. Formation of 4 can also be accomplished by a hydrolysis
involving the monohydrated compound {[n-Bu2Sn(OH2)(Phen)
(O3SC6H3-2,5-Me2)]+[2,5-Me2C6H3SO3]-} (Phen ) 1,10-
phenanthroline) (3). These studies point out the utility of
hydrated organotin cations as precursors for organotin hydrox-
ides. We are currently exploring pathways that will allow the
isolation of organotin hydroxides where the hydroxide groups
are not involved in bridging coordination.
Experimental Section
General Remarks. Solvents were distilled and dried prior to
use according to standard procedures. [n-Bu2SnO]n, 1,10-phenan-
throline (Phen) (Aldrich), L-menthol (Lancaster), cinnamyl alcohol
(Fluka), pyridine, and acetic anhydride (sd-fine, India) were
purchased and used as such without any further purification. 2,5-
Me2C6H3SO3H‚2H2O12 and 23a were prepared by literature methods.
Melting points were measured using a JSGW melting point
apparatus and are uncorrected. Elemental analyses were carried out
using a Thermoquest CE Instruments model EA/110 CHNS-O
elemental analyzer. Infrared spectra were recorded as KBr pellets
on a FT-IR Bruker-Vector model. 1H and 119Sn NMR spectra were
obtained on a JEOL-JNM Lambda 400 model spectrometer using
CDCl3, CD3OD, and (CD3)2SO solutions with shifts referenced to
tetramethylsilane (for 1H NMR) and tetramethyltin (for 119Sn NMR).
119Sn NMR spectra were recorded under broad-band decoupled
conditions.
Conclusions
Main-group organometallic compounds containing E-OH
bonds are of interest in view of their potential as synthons for
building heterometallic architectures. Organotin hydroxides are
generally obtained by hydrolysis of organotin halides. The
availability of discrete hydrated organotin cations opens up the
possibility of investigating whether such species can be hydro-
lyzed deliberately to generate organotin hydroxides. Accordingly
we have shown that {[n-Bu2Sn(OH2)4]2+[2,5-Me2C6H3SO3-]2}
(2) can be deliberately hydrolyzed by a mild base such as
pyridine to afford {[n-Bu2Sn(µ-OH)(O3SC6H3-2,5-Me2)]2}n (4),
which is a two-dimensional coordination polymer containing
Synthesis of 3. A suspension of 2 (0.33 g, 5.00 mmol) and Phen
(0.09 g, 5.00 mmol) in 10 mL of toluene was stirred gently for 15
min at 60 °C. The solution was filtered and kept for slow
(11) (a) Orita, A.; Sakamoto, K.; Ikeda, H.; Xiang, J.; Otera, J. Chem.
Lett. 2001, 40. (b) Wang, R.-H.; Hong, M.-C.; Luo, J.-H.; Cao, R.; Weng,
J.-B. Eur. J. Inorg. Chem. 2002, 2082. (c) Garc´ıa-Zarracino, R.; Ramos-
Quin˜ones, J.; Ho¨pfl, H. Inorg. Chem. 2003, 42, 3835. (d) Chandrasekhar,
V.; Thirumoorthi, R.; Azhakar, R. Organometallics 2007, 26, 26.
(12) Furniss, B. S.; Hannaford, A. J.; Smith, P. W. G.; Tatchell, A. R.
Vogel’s Textbook of Practical Organic Chemistry, 5th ed.; ELBS and
Longman: London, 1989.

Direct Hydrolysis of Hydrated Organotin Cations
Organometallics, Vol. 26, No. 11, 2007 2839
evaporation. Thick plate-like, colorless crystals appeared after 5
days. Yield: 0.31 g (80%, for isolated crystals). Mp: 136 °C. Anal.
Calcd for C36H49O7N2S2Sn (801.6 g) (%): C, 53.94, H, 5.78, N
3.49. Found: C, 53.8, H, 5.65, N, 3.26. IR (KBr, cm-1): 3428 [br,
ν(H2O)], 1254 [s, ν(SO3) asym. str.], 1145 [s, ν(SO3) assym. str.],
size ) 0.3 × 0.3 × 0.2 mm3; triclinic; P1h; a ) 10.6541(1) Å, b )
13.1098(2) Å, c ) 15.8103(2) Å; R ) 102.973(2)°, â ) 103.614-
(2)°, γ ) 113.463(2)°; V ) 1839.1(4) Å3; T ) 100(2) K; Z ) 2;
Dcalcd ) 1.447 Mg m-3; θ range 2.10 to 28.32°; 12 330 reflections
collected; 8220 independent reflections (Rint ) 0.0333); R1 )
0.0568, wR2 ) 0.1186 [for I > 2σ(I)]; R1 ) 0.0711, wR2 ) 0.1263
(for all data); GOF ) 1.025. For 4: size ) 0.3 × 0.2 × 0.2 mm3;
monoclinic; P2(1)/c; a ) 11.938(5) Å, b ) 12.140(5) Å, c )
14.522(5) Å; â ) 112.103(5)°; V ) 1950.0(13) Å3; T ) 153(2) K;
Z ) 4; Dcalcd ) 1.482 Mg m-3; θ range 4.14 to 25.02°; 9995
reflections collected; 3432 independent reflections (Rint ) 0.0311);
R1 ) 0.0285, wR2 ) 0.0690 [for I > 2σ(I)]; R1 ) 0.0321, wR2
) 0.0708 (for all data); GOF ) 1.047. The structures were solved
and refined by full-matrix least-squares on F2 using the SHELXTL
software package.13 Non-hydrogen atoms were refined with aniso-
tropic displacement parameters. The hydrogen atoms attached to
oxygen atoms of water and hydroxyl groups were located from the
difference map, and their positions were refined. All other hydrogen
atoms were included in idealized positions, and a riding model was
used. CCDC 630934 and 630935 contain the supplementary
crystallographic data for this paper.7 These data can be obtained
free of charge at www.ccdc.cam.ac.uk/conts/retrieving.html [or from
the Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: (int.) +44-1223/336-033; e-mail:
deposit@ccdc.cam.ac.uk]. Figures 1-4 and bonding parameters
were obtained from the DIAMOND 3.0 software package.14
1
1083 [s, ν(SO3) sym. str.], 995 [s, ν(SO3) ionic]. H NMR (400
MHz, CDCl3): δ 0.79-0.82 (m, 6H, CH3), 1.23-1.24 (m, 4H,
SnCH2), 1.45-1.54 (m, 8H, CH2CH2), 2.20 (s, 3H, Ar-CH3), 2.51
(s, 3H, Ar-CH3), 7.05 (m, 2H, Phen CH), 8.06 (m, 2H, Phen CH),
8.68 (d, 2H, Phen CH), 10.0 (d, 2H, Phen CH). 119Sn NMR (150
MHz, CDCl3): δ -413.5 (s).
Synthesis of 4. Method A: Pyridine (0.04 mL, 0.51 mmol) was
added dropwise to a suspension of 2 under stirring (0.23 g, 0.34
mmol) in 10 mL of toluene, and the contents were stirred overnight
at 60 °C. The solution turned turbid. Removal of solvent afforded
a solid residue. This was dissolved in methanol, slow evaporation
of which afforded colorless block-like crystals. Yield: 0.11 g (71%,
isolated crystals).
Method B: A mixture of 1 (0.40 g, 1.6 mmol) and 2,5-Me2C6H3-
SO3H‚xH2O (0.30 g, 1.6 mmol) in toluene (60 mL) was heated
under reflux for 7 h using Dean-Stark apparatus to remove the
water formed in the reaction by azeotropic distillation. A white
solid that formed was filtered and dried. Yield: 0.51 g (72%,
isolated solid). Crystals of 4 were grown by slow evaporation of
its methanolic solution. Mp: 156 °C. Anal. Calcd for C32H56O8S2-
Sn2 (870.3 g) (%): C 44.16, H 6.49. Found: C 43.91, H 6.25. IR
(KBr, cm-1): 3392 [br, ν(µ-OH)], 1259 [s, ν(SO3) assym. str.],
1183 [s, ν(SO3) assym. str.], 1087 [s, ν(SO3) sym. str.], 626 [m,
ν(C-S) str.]. 1H NMR (400 MHz, CD3OD): δ 0.76-0.92 (m, 6H,
CH3), 1.21-1.28 (m, 4H, SnCH2), 1.31-1.57 (m, 8H, CH2CH2),
2.23 (s, 3H, Ar-CH3), 2.59 (s, Ar-CH3), 7.08-7.18 (m, 2H,
aromatic CH), 7.61 (s, 1H, aromatic CH). 119Sn NMR (150 MHz,
CD3OD): δ -167.6 (s), -258.8 (s).
Acknowledgment. We are thankful to the Department of
Science and Technology, New Delhi, for financial support. P.S.
thanks the Council of Scientific and Industrial Research, India,
for a Senior Research Fellowship.
Supporting Information Available: IR spectroscopic data for
the reaction mixture of 4, ORTEP plots for compounds 3 and 4,
additional figure for compound 4, and crystallographic information
files (CIF) for compounds 3 and 4. These materials are available
free of charge via the Internet at http://pubs.acs.org.
Acetylation. Acetylation reactions were carried out according
to the procedure reported by us recently.3a,5
X-ray Crystallographic Study. The crystal data for compounds
3 and 4 were collected on a Bruker SMART APEX CCD
diffractrometer. The SMART software package (version 5.628) was
used for collecting data frames, the SAINT software package
(version 6.45) for integration of the intensity and scaling, and
SADABS for absorption correction. The details pertaining to the
data collection and refinement for crystals are as follows. For 3:
OM0701625
(13) Sheldrick, G. M. SHELXTL version 6.14; Bruker AXS Inc.:
Madison, WI, 2003.
(14) DIAMOND version 3.0; Crystal Impact GbR: Bonn, Germany, 2004.