Synthesis, structures and preliminary biological screening of bis(diphenyl)chlorotin complexes and adducts: Ph2ClSn-CH 2-R-CH2-SnClPh2, R = p-C6H 4, CH2CH2

Article abstract of DOI:10.1016/j.jorganchem.2005.12.040

The reaction between ClCH₂-R-CH₂Cl, R = p-C ₆H₄, and [Ph₃Sn]^-Li⁺ yields Ph₃Sn-CH₂-R-CH₂-SnPh₃ (1) in high yield. The related known compound R = CH₂CH₂ (1a) is synthesized by the reaction of the di-Grignard reagent BrMg(CH₂) ₄MgBr with two equivalents of Ph₃SnCl. Cleavage of a single Sn-Ph group at each tin centre of both compounds using HCl/Et ₂O yields the corresponding bis-chlorostannanes Ph ₂ClSn-CH₂-R-CH₂-SnClPh₂, R = (CH₂)₄ (2) and R = C₆H₄ (3), respectively. Compounds 1, 2 and 3 are crystalline solid materials and their single crystal X-ray structures are reported. In the solid state both 2 and 3 form self-assembled ladder structures involving alternating intermolecular Cl-Sn?Cl and Cl?Sn-Cl bonded chains at both ends of the distannanes with 5-coordinate tin atoms. Recrystallization of 3 from CH ₂Cl₂ in the presence of DMF yields the bis-DMF adduct (4) in which no self-assembled structures were noted. Evaluation of the chlorostannanes 2 and 3 against a suite of bacteria, Staphylococcus aureus, Escherichia coli and Photobacterium phosphoreum is reported and compared to the related mono-chlorostannanes Ph₂(CH₃)SnCl and Ph ₂(PhCH₂)SnCl.

Full text of DOI:10.1016/j.jorganchem.2005.12.040

Journal of Organometallic Chemistry 691 (2006) 1790–1796
www.elsevier.com/locate/jorganchem
Synthesis, structures and preliminary biological screening
of bis(diphenyl)chlorotin complexes and adducts:
Ph2ClSn–CH2–R–CH2–SnClPh2, R = p-C6H4, CH2CH2
Srawan K. Thodupunoori, Israel A. Alamudun, Francisco Cervantes-Lee,
*
Fabiola D. Gomez, Yazmin P. Carrasco, Keith H. Pannell
Department of Chemistry, University of Texas at El Paso, El Paso, TX 79968-0513, USA
Received 9 December 2005; accepted 10 December 2005
Available online 9 February 2006
Abstract
The reaction between ClCH2–R–CH2Cl, R = p-C6H4, and [Ph3Sn]ꢀLi+ yields Ph3Sn–CH2–R–CH2–SnPh3 (1) in high yield. The
related known compound R = CH2CH2 (1a) is synthesized by the reaction of the di-Grignard reagent BrMg(CH2)4MgBr with two equiv-
alents of Ph3SnCl. Cleavage of a single Sn–Ph group at each tin centre of both compounds using HCl/Et2O yields the corresponding bis-
chlorostannanes Ph2ClSn–CH2–R–CH2–SnClPh2, R = (CH2)4 (2) and R = C6H4 (3), respectively. Compounds 1, 2 and 3 are crystalline
solid materials and their single crystal X-ray structures are reported. In the solid state both 2 and 3 form self-assembled ladder structures
involving alternating intermolecular Cl–Snꢁ ꢁ ꢁCl and Clꢁ ꢁ ꢁSn–Cl bonded chains at both ends of the distannanes with 5-coordinate tin
atoms. Recrystallization of 3 from CH2Cl2 in the presence of DMF yields the bis-DMF adduct (4) in which no self-assembled structures
were noted. Evaluation of the chlorostannanes 2 and 3 against a suite of bacteria, Staphylococcus aureus, Escherichia coli and Photobac-
terium phosphoreum is reported and compared to the related mono-chlorostannanes Ph2(CH3)SnCl and Ph2(PhCH2)SnCl.
ꢀ 2006 Published by Elsevier B.V.
Keywords: Distannanes; Tin chlorides; X-ray structures; Self-assembly; Biocidal activity
1. Introduction
plexes [3], interest in OTs is still ongoing and justified.
Indeed, as noted by Champ [4], there is still a strong need
to further investigate such compounds to discern in more
detail the various aspects of their bioactivity, with perhaps
a goal of synthesizing new OTs that can be more targeted
and less environmentally problematical. We report bis-
organotin chlorides that exhibit interesting new self-assem-
bled ladder structures and compare their biological activity
against a suite of bacteria with their mono-tin analogs.
The societal use of organotin materials (OTs) is becom-
ing progressively a historical footnote due to the problem
of environmental contamination and their non-selective
biological activity [1]. Furthermore, Whalen et al. [2a,2b]
recently reported significant concentrations of butyl tins
in the blood of a random selection of US residents. In addi-
tion the same group observed that OTs had a significant
negative impact on the function of human natural killer
cells [2a,2c]. Together, these reports present a sobering
assessment on the future of OTs. However, since many
OTs offer significant industrial utility and promising anti-
cancer characteristics including the bis-organotin com-
2. Experimental
All reactions were performed in atmospheres of dry
nitrogen or argon using solvents dried by conventional
techniques. Triphenyltin chloride was purchased from
Gelest and the organic starting materials were purchased
from Aldrich. Analyses were performed by Galbraith
*
Corresponding author. Tel.: +1 915 747 5796; fax: +1 915 747 5748.
E-mail address: kpannell@utep.edu (K.H. Pannell).
0022-328X/$ - see front matter ꢀ 2006 Published by Elsevier B.V.
doi:10.1016/j.jorganchem.2005.12.040

S.K. Thodupunoori et al. / Journal of Organometallic Chemistry 691 (2006) 1790–1796
1791
Laboratories; NMR spectroscopy was performed using a
Bruker300 MHz spectrometer and crystal structures were
obtained using a Bruker SMART APEX CCD diffracto-
meter. Both 1,4-bis(triphenylstannyl)butane (1a), and 1,4-
bis-(diphenylchlorostannyl)butane (2) were synthesized
using published procedures [5,6].
0.0052 mol., 84%; m.p. 141–143 ꢁC. Anal. Calc. (Found):
C, 53.31 (52.92); H, 3.91 (3.95).
1H NMR (CDCl3, ppm): 7.45–7.35 (20, m, Sn–Ph), 7.02
(4, m, CH2–Ph), 3.11 [Sn–CH2,2J (Sn–H) 73.
13C NMR (CDCl3, ppm, J, Hz): 25.43 (Sn–CH2, 1J
119/117Sn–13C,
378/361);
138.07
(Sn–Ph,
1J
–
2.1. Synthesis of a,a1-bis(triphenylstannyl)-p-xylene (1)
119/117Sn–13C, 552/527), 136.05 (Sn–Ph, J 119/117Snavg
2
13C, 46), 129.09 (Sn–Ph, J 119/117Snavg–13C, 59), 130.37
(Sn–Ph, 4J 119/117Snavg–13C,13), 134.30 (Sn–CH2–Ph,
2J 119/117Sn–13C, 49/23), 128.49 (Sn–CH2–Ph, 3J
119/117Snavg–13C, 34).
3
To finely cut lithium wire, 0.8 g (0.115 mol.) in 50 ml of
tetrahydrofuran that had been sonicated for 2 h, was added
dropwise a solution of Ph3SnCl (10 g, 0.026 mol.) in 20 ml
of tetrahydrofuran at 0 ꢁC over 30 min. After the addition
was complete the reaction was stirred at 0 ꢁC for 1 h and
then allowed to reach ambient temperature and stirred
for 16 h to form a dark green/black coloured solution of
[Ph3Sn]ꢀLi+.
119Sn NMR (CDCl3, ppm): ꢀ24.67.
IR (cmꢀ1, CCl4): 3070 (s), 3053 (s), 3021 (m), 2994 (w),
2923 (bd. vw), 1971 (w), 1954 (w), 1896 (w), 1878 (w),
1817 (w), 1506 (s), 1430 (vs), 1074 (s), 727 (vs), 696 (vs).
To the above solution was added a 25 ml THF solution of
2.25 g (0.013 mol.) of p-dichloroxylene over 30 min at
ꢀ55 ꢁC. The suspension was stirred for 1 h at ꢀ55 ꢁC and
then allowed to reach ambient temperature and stirred for
16 h to form a brown/black solution. The solvent was
removed under vacuum and the residue was dissolved in a
solvent mixture of dichloromethane/hexanes (10:2), the
solution was filtered and concentrated. A white solid was
formed and after recrystallization from dichloromethane/
hexanes yielded 1, 9.35 g, 0.0116 mol., 45%: m.p. 165–
168 ꢁC. Anal. Calc. (Found): C, 65.71 (65.67); H, 4.76 (4.70).
2.3. Single crystal structural determination
Crystals of 1–4 were mounted on glass fibers. The X-ray
intensity data were measured on a Bruker SMART APEX
CCD area detector system equipped with a graphite mono-
chromator and
a
Mo Ka fine-focus sealed tube
˚
(k = 0.71073 A). Frames were collected with a scan width
of 0.30ꢁ in x and an exposure time of 10 s/frame. The
frames were integrated with the Bruker SAINT software
package using a narrow-frame integration algorithm. Anal-
ysis of the data showed negligible decay during data collec-
tion. Data were corrected for absorption effects using the
multiscan technique (SADABS). The structures were solved
and refined using the Bruker SHELXTL (Version 6.1012)
Software Package. The corresponding crystal and refine-
ment data for each compound are summarized in Table 1.
The structure of 3 was first solved at room temperature
and showed some disorder in one of the phenyl rings. Data
were then collected at 100k and the structure was found to
be statically disordered, having one of the phenyl rings in
two different orientations. The low temperature data
allowed simple modeling of the disorder by splitting the
disordered atoms (C6 and C60, C7 and C70, C9 and C90
and C10 and C100) between the two possible orientations
and refining the site occupancy for each atom, keeping
the total occupancy for each pair constrained to 1.000
using the SHELXTL software.
1H NMR (CDCl3, ppm, J, Hz); 7.52–7.27 (30, m, Ph),
2
6.81 [4, m, –CH2–Ph–], 2.94 [Sn–CH2, J (Sn–H) 67.4.
13C NMR (CDCl3, ppm); 19.
7
(Sn–CH2, 1J
(Sn–Ph,
119/117Sn–13C,
342/325);
138.81
1J
119/117Sn–13C, 491/469), 137.65 (Sn–Ph, 2J 119/117Sn–
13C, 55/36), 128.68 (Sn–Ph, 3J 119/117Sn–13C, 49/18),
129.16 (Sn–Ph, 4J 119/117Snavg–13C, 11); 136.20 (Sn–
2
CH2–Ph, J 119/117Sn–13C, 42/17), 128.13 (Sn–CH2–Ph,
3J 119/117Snavg–13C – 12).
119Sn NMR (CDCl3, ppm); ꢀ118.7.
IR (cmꢀ1, CCl4): 3066 (s), 3051 (m), 3018 (m), 2991 (w),
2916 (vw), 1967 (w), 1950 (w), 1892 (w), 1876 (w), 1816
(w), 1579 (vw), 1504 (m), 1429 (s), 1074 (m), 727 (vs),
696 (vs).
2.2. Synthesis of a,a1-bis(diphenylchlorostannyl)-p-xylene
(3)
2.4. Biocidal evaluation
To a suspension of 5.0 g (0.0062 mol.) of 1 in 35 ml of
dry dichloromethane was added dropwise 2.0 equiv. of
hydrogen chloride in diethyl ether (12.5 ml, 0.0123 mol.)
at ꢀ55 ꢁC over 30 min. The resulting mixture was stirred
at this temperature for 1 h and allowed to reach ambient
temperature. After 15 h the solvent was removed under
vacuum and the residue was washed with cold hexanes.
Purification was performed by recrystallization from
dichloromethane/hexanes mixture to yield 3, 3.75 g,
MIC determinations (NCCLS, M7-A4, 1997) [9].
Stock solutions of the organotin compounds were made
10ꢀ2 M in DMSO (Aldrich). A tenfold dilution in DMSO
of each stock compound was made, providing 10ꢀ3 M solu-
tions. Twofold serial dilutions of each compound were
obtained by using Mueller Hinton broth (Difco Laborato-
ries, Detroit, MI). The resulting concentrations ranged from
10ꢀ3 to 3.1 · 10ꢀ7 M. A 96-well polypropylene microdilu-
tion plate was used for each compound. 100 lL of each

1792
S.K. Thodupunoori et al. / Journal of Organometallic Chemistry 691 (2006) 1790–1796
Table 1
Crystal and refinement data for compounds 1–4
Compounds
1
2
3
4
Identification code
Empirical formula
Formula weight
Temperature (K)
028ST
C22H19Sn
804.12
296(2)
0.71073
993IS
C14H14ClSn
672.78
296(2)
0.71073
S108L
C16H14ClSn
684.79
100(2)
0.71073
108RT
C19H21ClNO
433.51
296(2)
0.71073
´
˚
Wavelength (A)
Crystal size (mm)
Crystal habit
Crystal system
Space group
0.50 · 0.40 · 0.40
Colorless prism
Monoclinic
C2/c
0.32 · 0.28 · 0.15
Colorless plate
Triclinic
0.24 · 0.20 · 0.02
Colorless plate
Monoclinic
P2(1)/n
0.20 · 0.20 · 0.14
Colorless chunk
Monoclinic
P2(1)/n
ꢀ
P1
Unit cell dimensions
˚
a (A)
13.175(3)
15.080(4)
19.667(5)
90
108.460(4)
90
3706.4(15)
8
1.441
12.9427(17)
9.1540(12)
6.3319(8)
99.996(2)
102.505(2)
100.884(2)
700.99(16)
2
16.0707(12)
16.4626(12)
5.6489(4)
90
110.8150(10)
90
1396.96(18)
4
1.628
9.759(3)
13.988(4)
13.543(4)
90
94.018
90
1844.2(9)
4
1.561
1.534
868
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
3
˚
V (A )
Z
Dcalc (Mg/m3)
Absorption coefficient (mmꢀ1
F(000)
1.594
1.985
330
)
1.376
1608
1.994
672
Detector distance (cm)
5.96
5.97
5.96
5.98
h Range for data collection (ꢁ)
Index ranges
2.12–28.30
ꢀ16 6 h 6 16,
ꢀ20 6 k 6 9,
ꢀ25 6 l 6 23
11465
1.64–28.27
ꢀ8 6 h 6 8,
ꢀ12 6 k 6 12,
ꢀ17 6 l 6 16
8077
1.52–28.24
ꢀ17 6 h 6 21,
ꢀ6 6 k 6 7,
ꢀ21 6 l 6 17
8313
2.10–23.26
ꢀ10 6 h 6 10,
ꢀ15 6 k 6 15,
ꢀ15 6 l 6 15
14879
Reflections collected
Independent reflections [Rint
Coverage of independent reflections
Absorption correction
]
4285 [0.0238]
92.80%
3199 [0.0214]
91.50%
3248 [0.0274]
93.90%
2638 [0.0414]
99.70%
SADABS
SADABS
SADABS
SADABS
Maximum/minimum transmission
Refinement technique
0.6091/0.5462
Full-matrix
least-squares on F2
ðF 2o ꢀ F 2c Þ
4285/0/208
1.21
0.047, 3839 data
0.1048, 3839 data
0.0541
0.7550/0.5691
Full-matrix
least-squares on F2
ðF 2o ꢀ F 2c Þ
3199/0/145
1.12
0.0299, 3063 data
0.0722, 3063 data
0.0316
0.9612/0.6461
Full-matrix
least-squares on F2
ðF 2o ꢀ F 2c Þ
3248/0/200
1.11
0.0378, 3034 data
0.0816, 3034 data
0.0415
0.8139/0.7490
Full-matrix
least-squares on F2
ðF 2o ꢀ F 2c Þ
2638/0/210
1.192
0.0316, 2559 data
0.0696, 2559 data
0.0331
P
P
P
P
2
2
2
2
Function minimized
Data/restraint/parameters
Goodness-of-fit on F2
R1; I > 2r(I)
wR2; I > 2r(I)
R1 all data
wR2 all data
Largest difference in peak and hole (eA
0.1083
0.481 and ꢀ0.896
0.0732
0.601 and ꢀ0.412
0.0834
1.137 and ꢀ0.912
0.0704
0.493 and ꢀ0.386
ꢀ3
˚
)
twofold dilution concentration were placed in triplicate in
each well. Escherichia coli (ATCC 25922), Staphylococcus
aureus (ATCC 25923) and Photobacterium phosphoreum
(ATCC 49387) were obtained from American Type Collec-
tion, Manassas, VA and was revived using trypticase soy
medium (Beckton Dickinson and Company, Cockeysville,
MD). Colonies of S. aureus were further transferred weekly
to tryptic soy agar plates (Beckton Dickinson and Company,
Cockeysville, MD). Three to five, isolated, morphologically
similar colonies, were transferred to a tube of 3 mL tryptic
soy broth medium (Beckton Dickinson and Company, Coc-
keysville, MD) and incubated at 37 ꢁC for 1–2 h. A bacterial
suspension was made by adding sterile saline solution (0.9%)
to the culture. It was further diluted in saline by a factor of
1:10 providing afinal population densityof 1ꢀ2 · 107 CFU’s
(colony forming units). The 96-well plate was innoculated
with 5 lL of the final bacterial suspension. Incubation of
the plate proceeded at 35 ꢁC for 16–20 h. A positive and neg-
ative growth controls containing 100 lL of Mueller Hinton
broth were present in each plate. The minimum inhibitory
concentration (MIC) resulted from recording the lower con-
centration which inhibited growth.
3. Results and discussion
3.1. Synthesis and spectroscopic characterizations
The formation of the two bis-triphenyltin compounds
was successfully accomplished in good yields using stan-
dard salt-elimination chemistries denoted in:
2½Ph3SnꢂꢀLiþ þ ClCH2–C6H4–p-CH2Cl
! Ph3SnCH2–C6H4–p-CH2SnPh3 ð1Þ
2Ph3SnCl þ MgBrðCH2Þ4MgBr
! Ph3SnðCH2Þ4SnPh3 ð1aÞ
ð1Þ
ð2Þ

S.K. Thodupunoori et al. / Journal of Organometallic Chemistry 691 (2006) 1790–1796
1793
Compound 1 has not been previously reported in the liter-
ature whereas 1a was first synthesized in 1954 via the same
route [5]. All spectroscopic data are in accord with the pro-
posed structures. For example, the 119Sn NMR solution
spectra exhibit resonances at ꢀ118.7 (1) and ꢀ100.0 ppm
(1a) in the general range for Ph3SnCH2 compounds and
the various coupling constants noted in Section 2 are also
in total accord with the literature [7].
Fig. 1. Molecular structure of Ph3SnCH2C6H4–p-CH2SnPh3 (1).
Fig. 2. Molecular structure of Ph2ClSnCH2C6H4–p-CH2SnPh2Cl (3).
Fig. 3. Molecular structure of Ph2ClSnCH2C6H4–p-CH2SnPh2Cl (DMF)2 (4).

1794
S.K. Thodupunoori et al. / Journal of Organometallic Chemistry 691 (2006) 1790–1796
The acid cleavage of aryl–tin bonds is well-established
dinated with DMF, Fig. 3. The single crystal structures of
both 1a and 2 have been reported [8,9]; however, in the case
of 2 the packing arrangement, now illustrated in Fig. 4
along with that of 3, was not reported [10].
and the commercially available reagent HCl/Et2O is partic-
ularly useful in this regard. The reactions of 1 and 1a to
form 2 and 3 can be monitored by 119Sn NMR and the for-
mation of any bis-chloro compounds held to a minimum.
The spectroscopic data of 2 and 3 are in total accord with
the proposed structures.
The simple tetraorganotin compound 1 has a non-
remarkable structure as expected. The two stannyl groups
are cis with respect to the bridging xylyl group, presumably
a function of the packing, although no intermolecular
interactions are noted in the packing diagram. The selected
bond lengths and angles recorded in Table 2 are in the nor-
mal ranges for OTs with similar structural units (Table 3).
The related bis-diphenylchlorotin compound 3 shows a
distorted tetrahedral structure about the Sn atom due to
an intermolecular Clꢁ ꢁ ꢁSn interaction, well-known in the
3.2. Single crystal X-ray structural analysis
We have been able to determine the single crystal struc-
tures of both the new compounds 1 and 3 and these molec-
ular structures are illustrated in Figs. 1 and 2, respectively,
together with a second structural analysis of 3 when coor-
Fig. 4. Packing diagram of 2 (b) and 3 (a) illustrating ladder self-assembled structure.

S.K. Thodupunoori et al. / Journal of Organometallic Chemistry 691 (2006) 1790–1796
1795
Table 2
Selected bond lengths (A)
The molecular structure 2 is reported in the literature and
it was noted that a degree of Clꢁ ꢁ ꢁSn intermolecular bonding
occurs; however, no detail was provided. The packing dia-
gram for 2 is shown in Fig. 4b and is remarkably similar to
that of 3. A very clear ladder-like structure is noted involving
both SnCl groups acting, as in 3, as both Lewis acid and
Lewis base. Despite this similarity, from the terminal and
˚
For l
Sn–C11
Sn–C17
For 2
Snl–Cl
Snl–C3
For 3
Sn–C5
Sn–C4
2.136(4)
2.143(4)
Sn–C5
Sn–C4
2.136(4)
2.159(4)
2.125(3)
2.128(3)
Sn1–C9
Sn1–C11
2.125(3)
2.3737(10)
˚
bridging Sn–Cl distances of 2.373 and 3.989 A, respectively,
2.119(4)
2.151(4)
Sn–C11
Sn–C1
2.122(4)
2.4166(12)
indicate that the intermolecular interaction is weaker, i.e.,
the terminal Sn–Cl bond is shorter, and the intermolecular
Clꢁ ꢁ ꢁSn internuclear distance greater, than in 3. The second-
For 4
Sn–C14
Sn–C4
Sn–Cl
2.143(4)
2.152(4)
2.4835(13)
Sn–C8
Sn–O
O–C5
2.143(4)
2.412(3)
1.228(5)
˚
ary Clꢁ ꢁ ꢁSn bonding distance of 3.989 A is one of the longest
reported where self-assembly can be designated and is essen-
tially the sum of the van der Waals radii for Sn and Cl.
Although rather longer than usually associated with an inter-
molecularly assembled situation this value may be compared
to those noted in the polymeric structure of SnCy2Cl2 where
Symmetry transformations used to generate equivalent atoms: #1 ꢀx + l,
ꢀy, ꢀz + 2.
Table 3
Bond angles (ꢁ)
˚
˚
the terminal and bridging distances are 2.407 A (2.371 A)
and 3.332 A (3.976 A), respectively [13].
˚
˚
For 1
C11–Sn–C5
C5–Sn–C17
C5–Sn–C4
107.11(14)
109.23(14)
111.19(15)
C11–Sn–C17
C11–Sn–C4
C17–Sn–C4
107.41(14)
110.06(16)
111.68(16)
With respect to the nature of the intermolecular self-
assembly, a useful measure of such interactions is the angu-
lar distortion that results at the tin atom [14]. For example,
assuming the Cl–Snꢁ ꢁ ꢁCl arrangement to be the incipient
axial portion of a trigonal bipyramidal structure, the differ-
ence between the sum of the equatorial angles and axial
angles would be zero for a tetrahedron and 90ꢁ for a trigo-
For 2
C1–Sn1–C9
C9–Sn1–C3
C9–Sn1–C11
114.31(12)
112.98(11)
101.28(9)
C1–Sn1–C3
C1–Sn1–C11
C3–Sn1–C11
118.68(11)
103.39(9)
103.25(9)
For 3
C5–Sn–C11
C11–Sn–C4
C11–Sn–C1
116.15(15)
120.22(14)
99.35(11)
C5–Sn–C4
C5–Sn–C1
C4–Sn–Cl
116.98(15)
101.85(13)
94.84(12)
nal bipyramid. Such an analysis for
3 reveals a
P
P
eq ꢀ ax of 57.3ꢁ and a much smaller value of 38.0ꢁ
is found for 2. By way of comparison in this study the cor-
responding values for the essentially unperturbed 1 is 7ꢁ,
while the bis-DMF adduct described below is 76ꢁ. These
data, in conjunction with the various C–Sn and Clꢁ ꢁ ꢁSn
internuclear distances reveal that a significant self-assem-
bling can be noted when considering the bond angles at
tin, even when the Clꢁ ꢁ ꢁSn internuclear distances are at,
or above, the sum of the van der Waals radii.
For 4
C14–Sn–C8
C8–Sn–C4
C8–Sn–O
C14–Sn–C1
C4–Sn–C1
116.47(14)
121.79(15)
84.51(12)
94.11(11)
94.21(14)
C14–Sn–C4
C 14–Sn–O
C4–Sn–O
C8–Sn–C1
O–Sn–C1
120.13(15)
87.72(12)
85.17(16)
94.34(11)
178.14(7)
Symmetry transformations used to generate equivalent atoms: #1 ꢀx + l,
ꢀy, ꢀz + 2.
The bis-DMF adduct 4 was obtained when 3 was recrys-
tallized from a CH2Cl2 solution containing a small amount
structural analysis of chlorotin compounds [11]. The two
stannyl groups are now trans with respect to the xylyl
group and this arrangement is best noted in the packing
diagram, Fig. 4a, where a ladder-like arrangement can be
noted. Each tin atom of the molecule is involved in a
Clꢁ ꢁ ꢁSn interaction with a neighbouring molecule. Further-
more in this interaction one of the two SnCl groups act as
donor while the other acts as an acceptor to the specific
individual neighbouring molecule. The situation is repro-
duced throughout the structure to produce the self-assem-
˚
bled ladders. The Sn–Cl covalent bond length is 2.417 A
while the secondary Clꢁ ꢁ ꢁSn internuclear distance is
˚
3.252 A. These distances are similar to those in other Sn–
Cl self-assembled bonding situations reported in the litera-
ture [11]. For example, in the polymeric structure of
Me3SnCl formed via intermolecular secondary Clꢁ ꢁ ꢁSn
bonding, the terminal and bridging Sn–Cl distances are
˚
reported as 2.430 and 3.269 A, respectively [12]. Indeed
˚
the intermolecular distance in 3 of 3.252 A is one of the
Fig. 5. Minimum inhibitory concentrations of Ph2ClSnCH2–R–CH2SnCl-
shortest secondary Clꢁ ꢁ ꢁSn distances in the literature.
Ph2(2,3)Ph2(CH3)SnCl (5) and Ph2(PhCH2)SnCl (6).

1796
S.K. Thodupunoori et al. / Journal of Organometallic Chemistry 691 (2006) 1790–1796
of DMF. Each tin atom is pentacoordinate with a single
DMF molecule coordinated via the O atom and no self-
assembling can be observed in the packing diagram. All
bond lengths are typical of such systems. It is interesting
that Jurkschat et al. reported a similar system in which
1,2-bis(diphenylchlorotin)ethane reacted with HMPA.
However, in this latter case only a single tin atom was coor-
dinated by the HMPA ligand, while the other tin atom
exhibited an interesting intramolecular secondary bond to
the chlorine atom of the other tin group [15]. The greater
distance between the two tin atoms in the case of 3 seems
to preclude such bonding in the present case. A similar
result was observed by Zobel et al. when two water mole-
cules were coordinated, one at each tin atom of the related
1,3-bis(diphenylchlorotin)propane [16].
of this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK, fax: +44 1223 336 033; email deposit@ccdc.
cam.ac.uk or www: http://www,ccdc.cam.ac.uk.
Acknowledgements
This research was supported by the NIH-SCORE
(GM-08012) and MARC (008048) programs and the
Welch Foundation, Houston, Texas (Grant #AH-0546).
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4. Supplementary material
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Crystallographic data for the structural analyses have
been deposited with the Cambridge Crystallographic Data
Centre, CCDC 290345–290348, (1–4, respectively). Copies