Study on the intramolecular transannular chalcogen-tin interactions in dithiastannecine compounds

Article abstract of DOI:10.1016/j.poly.2011.11.053

Dithiastannecine compounds of the type [{D(C₆H ₄CH₂S)₂}SnR¹R²] with different donor atoms D were prepared, where D = O and R¹ = R ² = Ph (4a); R¹ = Ph, R

Full text of DOI:10.1016/j.poly.2011.11.053

Polyhedron 33 (2012) 367–377
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Polyhedron
journal homepage: www.elsevier.com/locate/poly
Study on the intramolecular transannular chalcogen–tin interactions
in dithiastannecine compounds
a
a
Diego Martínez-Otero a, José G. Alvarado-Rodríguez a, , Julián Cruz-Borbolla , Noemí Andrade-López ,
⇑
Thangarasu Pandiyan b, Rafael Moreno-Esparza b, Marcos Flores-Alamo b, Jesús Cantillo-Castillo a
a Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Hidalgo, km. 4.5 Carretera Pachuca-Tulancingo, Col. Carboneras, Mineral de la Reforma, Hidalgo,
C.P. 42184 México, Mexico
b Facultad de Química, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, C.P. 04510 D.F. México, Mexico
a r t i c l e i n f o
a b s t r a c t
Dithiastannecine compounds of the type [{D(C6H4CH2S)2}SnR1R2] with different donor atoms D were pre-
Article history:
pared, where D = O and
R
1 = R2 = Ph (4a); R1 = Ph, R2 = Cl (5a); R1 = n-Bu, R2 = Cl (6a); D = S and
Received 20 October 2011
Accepted 28 November 2011
Available online 9 December 2011
R
1 = R2 = Ph (4b); R1 = Ph, R2 = Cl (5b); R1 = n-Bu, R2 = Cl (6b). The molecular structures of the monochloro
compounds 5a, 5b, 6a, and 6b were established by single-crystal X-ray diffraction and exhibit trigonal
bipyramidal geometry at the tin atom with different degrees of distortion being due a Dꢀ ꢀ ꢀSn interaction.
The spiro compounds [{D(C6H4CH2S)2}2Sn] with D = O (7a) and D = S (7b) were also synthesized and
structurally characterized; the molecular structure of 7a showed the tin atom with a bicapped tetrahe-
dral geometry. The behavior of all tin compounds in solution was investigated by NMR spectroscopy
revealing that the Dꢀ ꢀ ꢀSn interaction in solution was practically absent on the basis of the NMR chemical
shifts values. DFT calculations with ADF package using VWN/QZ4P were carried out for the 6a and 6b
compounds and showed that, in the topological analysis, bond critical points are present along the Dꢀ ꢀ ꢀSn
direction.
Keywords:
Tin compounds
Dithioligands
Hypervalent compounds
DFT studies
Ó 2011 Elsevier Ltd. All rights reserved.
1. Introduction
some germanium compounds of the type III containing rigid
ligands and observed that the interaction Dꢀ ꢀ ꢀA was modulated
The heavy group 14 metals have attracted great interest
because their environmental and toxicologic relevance [1], broad
diversity in coordination numbers [2], and unusual molecular
and supramolecular structures [3] as well as NMR properties [4,5].
On the other hand, the hypervalence of these heavy elements
have been extensively studied in a number of eight-membered
heterocycles containing one of these elements as electron-acceptor
atom A and the dithioligands {D(CH2CH2S)2}2ꢁ (type I), [2,6,7]
{D(C6H4S)2}2ꢁ (type II) [8–10], and {D(C6H4S)2O}2ꢁ (type III) [11]
where D is an electron-donor atom as nitrogen, oxygen, or sulfur
(Scheme 1). These studies have shown that the expected tetrahe-
dral geometry of A (A = Ge, Sn, Pb) is modified by the existence
of a non-covalent Dꢀ ꢀ ꢀA transannular interaction, leading to geom-
etries close to trigonal bipyramidal (tbp). For a given A acceptor,
these structural modifications are dependent on several factors
such as the donor abilities of D, the nature of the pendant ligands
R attached to A that influences its Lewis acidity, and the flexibility
of the dithioligand. Respect to this last point, we have reported
according to the nature of the R groups [11]. Thus, we decided to
study more flexible ligands attached to tin that could form larger
rings in order to gain a deeper insight into the nature of the trans-
annular interaction in larger heterocyclic compounds; to our
knowledge, there is no report on dithioligands coordinated to hea-
vy p-block elements able to form 10-membered rings of the type
IV, although several dialkoxide analogous ligands able to form this
type of rings were coordinated to different acceptor atoms as Al, Ti,
Ta, and Zr [12,13]. Other examples containing 10-membered rings
are those with tridentate trithioligands such as the tripodal tris-(2-
mercaptobenzyl)amine with nitrogen as donor atom that were
coordinated to Ga and In, where the existence of a transannular
interaction Nꢀ ꢀ ꢀA (A = Ga, In) leaded to tbp geometries in these
atrane compounds [14].
Following up on our studies on heterocyclic compounds of hea-
vy p-block metals, here we report the synthesis, structural charac-
terization, and a theoretical study of heterocyclic tin compounds
containing a flexible 10-membered ring of the type IV with D = O,
S, where the Dꢀ ꢀ ꢀSn interaction influences the local geometry of
the acceptor tin atom, despite the greater size of the central ring
compared with that observed in compounds of types I–III where
the interaction Dꢀ ꢀ ꢀA is well documented.
⇑
Corresponding author.
E-mail addresses: jgar@uaeh.edu.mx, josegalvarado@yahoo.com (J.G. Alvarado-
Rodríguez).
0277-5387/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2011.11.053

368
D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
2.2.1. O(C6H4CH2OH)2 (1a)
The above procedure was adopted to obtain 1a using the follow-
ing compounds: O(C6H5)2 (7.6 mL, 48 mmol), hexane (30 mL), TME-
DA, (20.9 mL, 139 mmol), n-BuLi 2.5 M (50 mL, 125 mmol),
paraformaldehyde (20.10 g, 670 mmol), chloroform (two portions
50 mL). Yield 48% (5.23 g). Mp 90 °C. Anal. Calc. for C14H14O3: C,
D
A
D
A
S
S
S
S
S
S
73.03; H, 6.13. Found: C, 73.01; H, 6.06%. IR (CsI):
3065, 3039, 2932, 2878, 1603, 1581, 1485, 1452, 1234, 1190,
1112, 1039, 1012, 882, 795, 752 cmꢁ1
Raman (420 mW):
= 3066, 2887, 1604, 1212, 1448, 1212, 1160, 1038, 790,
751 cmꢁ1. NMR: 1H (CDCl3) d = 7.35 dd [1H, H-3, 3JH3–H4 = 7.69 Hz,
m = 3342(OH),
R
R
R
R
R
R
.
m
I
O
II
3
3
4JH3–H5 = 1.46 Hz], d = 7.23 td [1H, H-5, JH5–H6 = 7.69 Hz, JH4–
4
3
H5 = 7.69 Hz, JH3–H5 = 1.46 Hz], d = 7.09 td [1H, H-4, JH4–
H5 = 7.69 Hz, JH3–H4 = 7.69 Hz, JH4–H6 = 1.46 Hz], d = 6.81 dd [1H,
3
4
3
4
H-6, JH5–H6 = 7.69 Hz, JH4–H6 = 1.46 Hz], d = 4.61
s [2H, H-1],
d = 3.54 s [1H, OH]; 13C{1H} (CDCl3): d = 154.8 (C7), 131.3 (C2),
130.2 (C3), 129.4 (C5), 123.7 (C4), 117.9 (C6), 61.4 (C1). EI-MS: m/
z (% intensity) 230 (10) [M]Å+, 212 (90) [O(C6H4CH2)2O]Å+, 195 (90)
[C14H11O]+, 181 (100) [C13H9O]+.
D
A
D
A
S
R
S
R
2.2.2. S(C6H4CH2OH)2 (1b)
S(C6H5)2 (8.05 mL, 48 mmol), hexane (30 mL), TMEDA, (20.9 mL,
139 mmol), n-BuLi 2.5 M (50 mL, 125 mmol), paraformaldehyde
(20.10 g, 670 mmol), chloroform (two portions 50 mL). Yield 52%
(6.16 g). Mp 84–85 °C. Anal. Calc. for C14H14O2S: C, 68.26; H, 5.73.
III
IV
Scheme 1. Heterocyclic compounds of heavy group 14 elements A containing
dithioligands with donor atoms D that lead to donor–acceptor interactions.
Found: C, 68.41; H, 5.84%. IR (CsI):
1589, 1568, 1466, 1441, 1196, 1031, 752 cmꢁ1. Raman (410 mW):
m
= 3066, 3054, 1587, 1196, 1036, 796, 685 cmꢁ1. NMR: 1H (CDCl3)
m = 3324(OH), 3059, 2875,
2. Experimental
3
4
d = 7.47 dd [1H, H-3, JH3–H4 = 7.69 Hz, JH3–H5 = 1.49 Hz], d = 7.29
ddd [1H, H-4, 3JH3–H4 = 7.69 Hz, 3JH4–H5 = 7.32 Hz, 4JH4–H6
1.49 Hz], d = 7.21 ddd [1H, H-5, 3JH5–H6 = 7.69 Hz, 3JH4–H5 = 7.32 Hz,
2.1. Materials and physical measurements
=
3
4
All the starting reagents were of analytical grade and used with-
out further purification. Solvents were dried by standard methods
and distilled prior to use. O(C6H5)2, S(C6H5)2, n-BuLi 2.5 M in hex-
anes, N,N,N0,N0-tetramethylethylendiammine (TMEDA), parafor-
maldehyde powder, Ph2SnCl2, n-BuSnCl3, SnCl4, Me2SnCl2, 1,4-
diazabicyclo-[2.2.2]-octane (DABCO), and hydrochloric acid were
purchased from Aldrich and used as supplied. Melting points of
the compounds determined on a Mel-Temp II instrument are re-
ported without correction. Elemental analyses were recorded on
a Perkin-Elmer Series II CHNS/O Analyzer. Electron-impact mass
spectra (EI-MS) were measured on either Finnigan MAT 8230 or
Varian MAT CH5 instrument. The IR spectra (4000–400 cmꢁ1) were
recorded on a Perkin-Elmer System 2000 FT-IR spectrometer as KBr
pellets and in CsI films. The Raman spectra in solid state (4000–
100 cmꢁ1) were recorded on a Perkin-Elmer Spectrum GX NIR
FT-RAMAN spectrometer with 10–280 mW laser power and
4 cmꢁ1 resolution. 1H, 13C{1H}, and 119Sn{1H} NMR spectra were re-
corded on a Jeol Eclipse 400 spectrometer operating at 399.78,
100.53, and 149.03 MHz, respectively. The chemical shifts are re-
ported in ppm with respect to the references and stated relative
to external tetramethylsilane (TMS) for 1H and 13C NMR, and
Me4Sn for 119Sn NMR spectroscopy. All the spectra were acquired
at room temperature (25 °C).
4JH3–H5 = 1.49 Hz], d = 7.14 dd [1H, H-6, JH5–H6 = 7.69 Hz, JH4–
H6 = 1.49 Hz], d = 4.75 s [2H, H-1], d = 2.25 s [1H, OH]; 13C{1H}
(CDCl3): d = 141.2 (C7), 133.3 (C2), 132.3 (C6), 128.8 (C3), 128.7
(C5), 128.0 (C4), 63.6 (C1). EI-MS: m/z (% intensity) 246 (88) [M]Å+,
228 (91) [MꢁH2O]Å+, 211 (65) [C14H13S]+, 197 (100) [C13H7S]+.
2.3. General synthesis of the dibromo compounds D(C6H4CH2Br)
(D = O, 2a; S, 2b)
Aqueous HBr was added to a solution of 1 dissolved in toluene;
the resulting mixture was refluxed for 24 h. After the reaction, the
compound 2 was extracted by using chloroform; the organic layer
was dried by means of a column filled with Celite and anhydrous
Na2SO4. After evaporation to dryness, a solid was obtained and
washed with ethanol.
2.3.1. O(C6H4CH2Br)2 (2a)
Compound 1a (1.00 g, 4.3 mmol), toluene (15 mL), HBr (1.5 mL,
13.04 mmol). Yield 91% colorless crystals (1.4 g). Mp 77–78 °C.
Anal. Calc. for C14H12Br2O: C, 47.23; H, 3.40. Found: C, 47.48; H,
3.31%. IR (CsI):
1185, 1086, 899, 755, 605 cmꢁ1. Raman (60 mW):
1608, 1225, 1158, 1039, 797, 602 cmꢁ1. NMR: 1H (CDCl3) d = 7.47
m
= 3036, 2981, 1579, 1486, 1450, 1241, 1220,
m
= 3058, 2983,
3
4
dd [1H, H-3, JH3–H4 = 8.06 Hz, JH3–H5 = 1.47 Hz], d = 7.25 td [1H,
3
3
4
2.2. General synthesis of the diols D(C6H4CH2OH) (D = O, 1a; S, 1b)
H-5, JH5–H6 = 8.06 Hz, JH4–H5 = 8.06 Hz, JH3–H5 = 1.47 Hz], d = 7.11
3
3
t [1H, H-4, JH3–H4 = 7.33 Hz, JH4–H5 = 7.33 Hz], d = 6.83 d [1H, H-
3
TMEDA was added to a solution of D(C6H5)2 in hexane and the
resulting mixture was cooled to 0 °C and then n-BuLi 2.5 M in hex-
anes was added slowly. After the mixture was stirred for 24 h,
paraformaldehyde in small portions was added and then refluxed
for 48 h. The mixture was acidified using HCl to pH 2, and the com-
pound was extracted with chloroform. The organic layer was dried
by means of a column filled with Celite and anhydrous Na2SO4 and
then evaporated to dryness; a solid was obtained and washed with
a solvent mixture of hexane–ethyl acetate.
6, JH5–H6 = 8.06 Hz], d = 4.64 s
[2H, H-1]; 13C{1H} (CDCl3):
d = 154.9 (C7), 131.5 (C3), 130.3 (C5), 129.0 (C2), 124.0 (C4),
118.6 (C6), 28.2 (C1). EI-MS: m/z (% intensity) 355 (5) [M]+ꢁ1,
275 (40) [C14H12OBr]+, 195 (100) [C14H11O]+, 181 (30) [C13H9O]+.
2.3.2. S(C6H4CH2Br)2 (2b)
Compound 1b (2.00 g, 7.6 mmol), toluene (15 mL), HBr (2.8 mL,
24.1 mmol). Yield 95% colorless crystals (2.67 g). Mp 65–66 °C.
Anal. Calc. for C14H12Br2S: C, 45.19; H, 3.25. Found: C, 45.71; H,

D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
369
3.44%. IR (CsI):
756, 605 cmꢁ1. Raman (25 mW):
602, 444 cmꢁ1. NMR: 1H (CDCl3) d = 7.46 d [1H, H-3, JH3–H4
m
= 3058, 2966, 1586, 1468, 1441, 1219, 1037, 818,
Mp 62–64 °C. Anal. Calc. for C26H22OS2Sn: C, 58.56; H, 4.16. Found:
C, 59.40; H, 4.28%. IR (CsI): = 3065, 3017, 2917, 2849, 1485, 1453,
1430, 1241, 1216, 1187, 755, 697, 667 cmꢁ1. Raman (360 mW):
= 3052, 2933, 1603, 1577, 1235, 1216, 1156, 1038, 997, 758,
666, 342 (C–Sn) cmꢁ1. NMR: 119Sn (CDCl3) d = 33.6; 1H (CDCl3)
m
= 3058, 2971, 1587, 1219, 1038,
m
3
=
3
3
7.33 Hz], d = 7.25 dd [1H, H-4, JH4–H5 = 8.06 Hz, JH3–H4 = 7.33 Hz],
m
3
3
d = 7.21 dd [1H, H-5, JH4–H5 = 8.06 Hz, JH5–H6 = 7.33 Hz], d = 7.16
d [1H, H-6, 3JH5–H6 = 7.33 Hz], d = 4.70 s [2H, H-1]; 13C{1H} (CDCl3):
d = 138.5 (C7), 135.2 (C2), 133.1 (C6), 131.1 (C3), 129.7 (C5), 128.2
(C4), 31.8 (C1). EI-MS: m/z (% intensity) 372 (30) [M]Å+, 291 (45)
[MꢁBr]+, 211 (100) [C14H11S]+, 197 (55) [C13H7S]+.
3
4
d = 7.51 m [2H, H-9], d = 7.44 dd [1H, H-3, JH3–H4 = 7.32 Hz, JH3–
H5 = 1.83 Hz], d = 7.37 m [3H, H-10, H-11], d = 7.20 td [1H, H-5,
3
4
3JH5–H6 = 7.69 Hz, JH4–H5 = 7.69 Hz, JH3–H5 = 1.83 Hz], d = 7.14 ddd
3
3
4
[1H, H-4, JH4–H5 = 7.69 Hz, JH3–H4 = 7.32 Hz, JH4–H6 = 1.46 Hz],
3
4
d = 6.60 dd [1H, H-6, JH5–H6 = 7.69 Hz, JH4–H6 = 1.46 Hz], d = 4.03
s [2H, H-1, JH1—119 ¼ 6:12], 13C{1H} (CDCl3): d = 153.7 (C7),
3
2.4. General synthesis of the dithiol compounds D(C6H4CH2SH) (D = O,
3a; S, 3b)
Sn
139.1 (C8), 136.0 (C9), 133.3 (C2), 130.7 (C3), 130.0 (C11), 128.9
(C10), 128.6 (C5), 124.3 (C4), 118.0 (C6), 27.1 (C1). EI-MS: m/z (%
intensity) 534 (3) [M]Å+, 457 (5) [C20H17OS2Sn]+, 260 (15)
[C14H12OS2]Å+, 227 (40) [C14H11OS]+, 195 (100) [C14H11O]+, 181
(27) [C13H9O]+.
To a solution of 2 dissolved in acetone, thiourea was added and
the solution mixture was refluxed for 24 h; when the solution was
cooled to room temperature, a white solid obtained was filtered
off and then it was mixed with an aqueous solution of potassium
hydroxide. The resulting mixture was refluxed for 4 h and then let
it to reach room temperature. The mixture was acidified with HCl
to pH 2, extracted with chloroform and the organic layer was dried
by means of a column filled with Celite and anhydrous Na2SO4. After
evaporation of the organic solvent, an oily compound was obtained.
2.5.2. [{O(C6H4CH2S)2}SnPhCl] (5a)
PhSnCl3 (0.57 g, 1.88 mmol), 3a (0.5 g, 1.90 mmol), DABCO
(0.21 g 1.90 mmol) dichloromethane (30 mL) Yield 65% (0.61 g).
Mp 122–123 °C. Anal. Calc. for C20H17ClOS2Sn: C, 48.86; H, 3.49.
Found: C, 48.59; H, 3.41%. IR (CsI):
m
= 3064, 2932, 1579, 1484,
1452, 1431, 1232, 1183, 1099, 900, 754, 728 cmꢁ1
.
Raman
2.4.1. O(C6H4CH2SH)2 (3a)
(360 mW): m = 3062, 2938, 1604, 1238, 1214, 1157, 1033, 997,
Compound 2a (1.50 g, 4.16 mmol), ethanol (30 mL), thiourea
(0.70 g, 9.19 mmol), KOH (0.90 g, 16.7 mmol), ethanol (30 mL).
Yield 75% Yellow oil (0.83 g). Anal. Calc. for C14H12OS2: C, 64.08;
660, 328, 243 cmꢁ1. NMR: 119Sn (CDCl3) d = 19.5; 1H (CDCl3)
d = 7.40 m [4H, H-9, H10], d = 7.32 m [3H, H-3, H-11], d = 7.17 m
3
[4H, H-4, H-5], d = 6.48 d [2H, H-6, JH5–H6 = 7.32 Hz], d = 4.03 s
[2H, H-1, JH1—119 ¼ 93:7], 13C{1H} (CDCl3): d = 153.2 (C7), 138.8
3
H, 5.38. Found: C, 63.53; H, 5.27%. IR (CsI):
2554 (SH), 1578, 1484, 1451, 1236, 1186, 1103, 792, 752 cmꢁ1. Ra-
man (420 mW): = 3060, 2938, 2569 (SH), 1606, 1249, 1216, 1157,
1039, 785, 680 cmꢁ1. NMR: 1H (CDCl3) d = 7.39 d [1H, H-3, JH3–
m
= 3090, 3035, 2937,
Sn
(C8), 134.7 (C9), 132.7 (C2), 131.1 (C11), 130.4 (C3), 129.4 (C5,
m
C10), 125.1 (C4), 118.0 (C6), 28.2 (C1). EI-MS: m/z (% intensity)
492 (5) [M]Å+, 457 (5%) [MꢁCl]+, 415 (<5%) [MꢁPh]+ 195 (100)
[C14H11O]+, 181 (25) [C13H9O]+.
3
3
3
H4 = 7.32 Hz], d = 7.20 dd [1H, H-5, JH5–H5 = 8.06 Hz, JH4–H5
=
3
3
7.69 Hz], d = 7.09 dd [1H, H-4, JH4–H5 = 7.69 Hz, JH3–H4 = 7.32 Hz],
3
3
d = 6.80 d [1H, H-6, JH5–H6 = 8.06 Hz], d = 3.83 d [2H, H-1, JH1–
SH = 8.06 Hz], d = 1.99 t [1H, SH, 3JH1–SH = 8.06 Hz]; 13C{1H} (CDCl3):
d = 154.3 (C7), 132.2 (C2), 130.2 (C3), 128.6 (C5), 123.8 (C4), 118.2
(C6), 23.8 (C1). EI-MS: m/z (% intensity) 262 (30) [M]Å+, 228 (55)
[O(C6H4CH2)2S]Å+, 195 (100) [C14H11O]+, 183 (70) [C13H11O]+ 181
(70) [C13H9O]+.
2.5.3. [{O(C6H4CH2S)2}Sn(n-Bu)Cl] (6a)
n-BuSnCl3 (0.54 g, 2.09 mmol), 3a (0.5 g, 1.90 mmol), DABCO
(0.21 g 1.90 mmol) dichloromethane (30 mL) Yield 41% (0.36 g).
Mp 103 °C. Anal. Calc. for C18H21ClOS2Sn: C, 45.84; H, 4.49. Found:
C, 45.61; H, 4.62%. IR (CsI):
m
= 3090, 2958, 2927, 2870, 1579, 1485,
1453, 1229, 1181, 1097, 900, 795, 755, 668 cmꢁ1
.
Raman
(420 mW):
m = 3061, 2962, 2933, 1605, 1234, 1215, 1154, 1036,
2.4.2. S(C6H4CH2SH)2 (3b)
679, 596, 351, 333, 241 (C–Sn) cmꢁ1
.
NMR: 119Sn (CDCl3)
3
Compound 2b (1.46 g, 3.92 mmol), acetone (30 mL), thiourea
(0.66 g, 8.7 mmol), KOH (0.88 g, 15.7 mmol), water (10 mL). Yield
70% Yellow oil (0.77 g). Anal. Calc. for C14H14S3: C, 60.39; H, 5.07.
d = 75.6; 1H (CDCl3) d = 7.38
d
[1H, H-3, JH3–H4 = 7.69 Hz],
3
3
d = 7.25 t [1H, H-5, JH5–H6 = 7.69 Hz, JH4–H5 = 7.69 Hz], d = 7.17 t
3
3
[1H, H-4, JH4–H5 = 7.69 Hz, JH3–H4 = 7.69 Hz], d = 6.71 d [1H, H-6,
3
Found: C, 59.85; H, 5.07%. IR (CsI):
m
= 3055, 3008, 2933, 2561
3JH5–H6 = 7.69 Hz], d = 3.92
s
[2H, H-1, JH1—119 ¼ 83:1 Hz],
Sn
3
(SH), 1586, 1466, 1439, 1247, 1039, 755 cmꢁ1. Raman (360 mW):
d = 1.90 t [2H, H-8, JH8–H9 = 7.69, JH8—119 ¼ 78:7 Hz], d = 1.50 q
3
Sn
3
3
m
= 3051, 2936, 2563(SH), 1586, 1247, 1039, 685 cmꢁ1. NMR: 1H
[2H, H-9, JH8–H9
,
JH9–H10 = 7.69, JH8—119 ¼ 12:19 Hz], d = 1.27 sx
3
Sn
3
3
3
(CDCl3) d = 7.38 d [1H, H-3, JH3–H4 = 7.32 Hz], d = 7.25 t [1H, H-4,
[2H, H-10, JH9–H10
,
3JH10–H11 = 7.69], d = 0.79 t [3H, H-11, JH10–
3JH3–H4 = 7.32 Hz, JH4–H5 = 7.32 Hz], d = 7.15 m [2H, H-5, H-6],
H11 = 7.69] 13C{1H} (CDCl3): d = 153.0 (C7), 133.2 (C2), 130.6 (C3),
129.5 (C5), 125.3 (C4), 118.0 (C6), 27.8 (C1), 27.1 (C9), 26.2 (C8),
25.7.1 (C10), 13.6 (C11). EI-MS: m/z (% intensity) 472 (3) [M]Å+,
437 (7) [C18H21OS2Sn]+, 415 (8) [C14H12OS2SnCl]+, 379 (5)
[C14H11OS2Sn]+, 260 (15) [C14H12OS2]Å+, 227 (40) [C14H11OS]+, 195
(100) [C14H11O]+, 181 (35) [C13H9O]+.
3
3
3
d = 3.88 d [2H, H-1, JH1–SH = 7.81 Hz], d = 2.01 t [1H, SH, JH1–
SH = 7.81 Hz]; 13C{1H} (CDCl3): d = 141.1 (C7), 133.8 (C2), 132.6
(6), 129.8 (C3), 128.3 (C5), 128.1 (C4), 27.6 (C1). EI-MS: m/z (%
intensity) 278 (50) [M]Å+, 244 (15) [MꢁH2S]Å+, 211 (90) [C14H11s]+,
197 (100) [C13H9S]+.
2.5. General synthesis of the dithiastannecine compounds 4–7
2.5.4. [{O(C6H4CH2S)2}2Sn] (7a)
SnCl4 (0.14 g, 0.56 mmol), 3a (0.3 g, 1.14 mmol), DABCO (0.13 g
1.19 mmol) dichloromethane (30 mL) Yield 45% (0.33 g). Mp
174 °C. Anal. Calc. for C28H24O2S4Sn: C, 52.59; H, 3.78. Found: C,
A tin compound (RnSnCl4ꢁn) was added to a solution of 3 and
DABCO in chloroform; the reaction mixture was stirred for 24 h.
After the reaction, the DABCO chlorohydrate was filtered off and
the remaining solution was slowly evaporated to dryness to get a
solid product.
52.32; H, 3.73%. IR (CsI):
1235, 1184, 1097, 900, 794, 752, 666 cmꢁ1. Raman (420 mW)
= 3067, 3048, 2952, 2926, 1603, 1236, 1217, 1152, 1035, 667,
332 (C–Sn) cmꢁ1. NMR: 119Sn (CDCl3) d = 125.4; 1H (CDCl3) d = 7.28
m = 3090, 2917, 2848, 1579, 1483, 1452,
m
3
3
2.5.1. [{O(C6H4CH2S)2}SnPh2] (4a)
Ph2SnCl2 (0.42 g, 1.21 mmol), 3a (0.3 g, 1.14 mmol), DABCO
(0.13 g 1.19 mmol) dichloromethane (30 mL) Yield 40% (0.25 g).
d [1H, H-3, JH3–H4 = 7.32 Hz], d = 7.18 dd [1H, H-5, JH5–H6 =
3
3
8.06 Hz, JH4–H5 = 7.32 Hz], d = 7.05 t[1H, H-4, JH4–H5 = 7.32 Hz,
3JH3–H4 = 7.32 Hz], d = 6.73 d[1H, H-6, JH5–H6 = 8.06 Hz], d = 3.92 s
3

370
D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
[2H, H-1, JH1—119 ¼ 88:17], 13C{1H} (CDCl3): d = 153.5 (C7), 132.6
128.1 (C4), 32.5 (C1). EI-MS: m/z (% intensity) 276 (25%)
[C14H12S3]+, 244 (78) [C14H12S2]+, 211 (100) [C14H11S]+, 197 (37)
[C13H7S]+.
3
Sn
(C2), 130.5 (C3), 128.7 (C5), 124.2 (C4), 117.9 (C6), 28.2 (C1). EI-
MS: m/z (% intensity) 640 (1) [M]Å+, 260 15) [C14H12OS2] Å+, 228
(35) [C14H12OS]Å+, 195 (100) [C14H11O]+, 181 (35) [C13H9O]+.
2.6. X–ray crystallography and structure solution
2.5.5. [{S(C6H4CH2S)2}SnPh2] (4b)
Ph2SnCl2 (0.62 g, 1.80 mmol), 3b (0.5 g, 1.80 mmol), DABCO
(0.20 g 1.78 mmol) dichloromethane (30 mL) Yield 45% (0.44 g).
Mp 53–55 °C. Anal. Calc. for C26H22S3Sn: C, 56.84; H, 4.04. Found:
Suitable single crystals of compounds 1a, 6b, and 7a were
grown from a chloroform solution by slow evaporation; crystals
of 5a, 5b, and 6a were grown form dichloromethane solution.
X-ray diffraction data of 1a were collected at room temperature
C, 57.18; H, 4.24%. IR (CsI):
m
= 3062, 3010, 2928, 1585, 1478,
1467, 1429, 1231, 1071, 759, 730, 696, 448 cmꢁ1
.
Raman
on a CCD SMART 6000 diffractometer through the use of MoK
a
(340 mW):
m = 3048, 2927, 1586, 1233, 1198, 1160, 1038, 997,
radiation (k = 0.71073 Å, graphite monochromator). Data were
integrated, scaled, sorted, and averaged using the SMART software
package. An empirical absorption correction based on the multiple
measurement of equivalent reflections was applied by using the
program SADABS [15]. X-ray diffraction data of 5a, 6a, 6b, and 7a
were collected at 141 K on an Oxford Diffraction Gemini CCD
655, 347, 236 cmꢁ1. NMR: 119Sn (CDCl3) d = 37.5; 1H (CDCl3)
d = 7.77 m [2H, H-9], d = 7.47 m [3H, H-10, H-11], d = 7.38 d [1H,
3
3
H-3, JH3–H4 = 7.69 Hz], d = 7.28 td [1H, H-4, JH3–H4 = 7.69 Hz,
3JH4–H5 = 7.69 Hz, JH4–H6 = 1.83 Hz], d = 7.23 m [2H, H-5, H-6],
4
d = 4.06 s [2H, H-1, JH1—119 ¼ 55:0]; 13C{1H} (CDCl3): d = 143.4
3
Sn
(C7), 140.7 (C8), 136.3 (C2), 135.9 (C9), 133.8 (C6), 130.5(C3),
diffractometer with graphite-monochromated MoK
a radiation
130.2 (C11), 129.1 (C10), 128.7 (C5), 128.0 (C4), 31.1 (C1). EI-MS:
m/z (% intensity) 550 (5) [M]Å+, 473 (70) [MꢁPh]+, 396 (9)
[Mꢁ2Ph]+, 211 (100) [C14H11S]+, 197 (73) [C13H7S]+.
(k = 0.71073 Å); for 5b CuK radiation (k = 1.54184 Å) was used.
a
Data were integrated, scaled, sorted, and averaged using the
CrysAlis software package [16]. An analytical numeric absorption
correction using a multifaceted crystal model was applied by using
the CrysAlis software. The structures were solved by direct meth-
ods, using SHELXTL NT Version 5.10 and refined by full-matrix least
squares against F2 [17]. The displacement parameters of non-
hydrogen atoms were anisotropically refined. The positions of the
2.5.6. [{S(C6H4CH2S)2}SnPhCl] (5b)
PhSnCl3 (0.55 g, 1.82 mmol), 3b (0.5 g, 1.80 mmol), DABCO
(0.20 g 1.78 mmol) dichloromethane (30 mL) Yield 50% (0.46 g).
Mp 116–117 °C. Anal. Calc. for C20H17ClS3Sn: C, 47.31; H, 3.37.
Found: C, 46.58; H, 3.20%. IR (CsI):
m = 3062, 3009, 2927, 1585,
hydrogen atoms were kept fixed with
a common isotropic
1468, 1443, 1431, 1232, 1038, 759, 730, 693, 666, 445 cmꢁ1. Ra-
displacement parameter. The absolute structure of 6a was
determined following the reported methods with a Flack parameter
of ꢁ0.014(12) [18]. Selected crystallographic data are given in
Table 6.
man (260 mW):
m = 3056, 3014, 2925, 1585, 1233, 1200, 1161,
1036, 996, 660, 356, 307, 236, 199 cmꢁ1. NMR 119Sn (CDCl3)
d = ꢁ42.3 Hz; 1H (CDCl3) d = 7.65 m [2H, H-9], d = 7.46 m [3H, H-
10, H-11], d = 7.37 m [2H, H-3, H-4], d = 7.24 m [2H, H-5, H-6],
d = 3.24 s [2H, H-1, JH1—119 ¼ 94:5]; 13C{1H} (CDCl3): d = 142.7
3
Sn
3. Results and discussion
(C7), 130.9 (C8), 134.4 (C2, C9), 130.4 (C6), 129.6 (C3), 130.4
(C11), 129.8 (C10), 128.8 (C5, C4), 31.4 (C1). EI-MS: m/z (% inten-
3.1. Synthesis of the dithioligands D(C6H4CH2SH)2 (D = O, S)
sity) 276 (36) [C14H12S3]+, 211 (63) [C14H11S]+, 197 (44) [C13H7S]+.
Ditihioligands 3a and 3b were prepared by linear synthesis
from diphenylether and diphenylthioether, respectively (the letter
a refers to the compound with D = oxygen and b to the compound
with D = sulfur, see Scheme 2 and Section 2, for details).
2.5.7. [{S(C6H4CH2S)2}Sn(n-Bu)Cl] (6b)
n-BuSnCl3 (0.51 g, 1.82 mmol), 3b (0.5 g, 1.80 mmol), DABCO
(0.20 g 1.78 mmol) dichloromethane (30 mL) Yield 55% (0.48 g).
Mp 95–96 °C. Anal. Calc. for C18H21ClS3Sn: C, 44.33; H, 4.34. Found:
C, 44.51; H, 3.40%. IR (CsI):
m
= 3059, 3008, 2957, 2925, 2869, 1586,
1467, 1442, 1231, 1038, 760, 666 cmꢁ1
.
Raman (360 mW):
3.2. Synthesis of the tin compounds 4–7
m
= 3061, 2929, 2908, 1587, 1234, 1225, 1204, 1160, 1036, 512,
369, 345, 241 cmꢁ1. NMR: 119Sn (CDCl3) d = 13.2; 1H (CDCl3)
d = 7.35 m [1H, H-3], d = 7.12 m [3H, H-4, H-5, H-6], d = 3.85 s
The reaction of 3a or 3b with the corresponding tin chloride
compound dissolved in chloroform in the presence of the deproto-
nating agent DABCO yielded the corresponding compounds 4–7
with yields ranging from 65% to 40%. All tin compounds are air-sta-
ble and soluble in chloroform or in toluene.
3
3
[2H, H-1, JH1—119 ¼ 80:9 Hz], d = 2.18 t [2H, H-8, JH8–H9 = 7.86,
Sn
3
3
3JH1—119 ¼ 65:9 Hz], d = 1.81 q [2H, H-9, JH8–H9, JH9–H10 = 7.86,
Sn
3
3
3JH8—119 ¼ 129:6 Hz], d = 1.44 sextuplet [2H, H-10, JH9–H10, JH10–
Sn
H11 = 7.69], d = 0.89 t [3H, H-11, JH10–H11 = 7.69]; 13C{1H} (CDCl3):
3
3.3. Vibrational spectroscopy
d = 142.6 (C7), 132.5 (C2), 130.5 (C6), 129.9 (C3), 128.8 (C5, C4),
31.7 (C8), 31.2 (C1), 27.9 (C9), 25.8 (C10), 13.7 (C11). EI-MS: m/z
(% intensity) 488 (5%) [M]Å+, 431 (87) [MꢁnBu]+, 396 (10)
[MꢁClꢁnBu]+, 211 (100) [C14H11S]+, 197 (75) [C13H7S]+.
The IR spectra as well as the Raman spectra (data in parenthe-
ses) of ligands 3a and 3b display bands of medium intensity at
2564 (2570) and 2561 (2565) cmꢁ1 assigned to the –SH vibration
group; these bands vanished in the corresponding spectra of the
compounds 4–7, thus indicating that the deprotonation of the thiol
groups occurred upon complex formation. This is consistent with
2.5.8. [{S(C6H4CH2S)2}2Sn] (7b)
SnCl4 (0.22 g, 0.85 mmol), 3b (0.5 g, 1.80 mmol), DABCO (0.20 g
1.78 mmol) dichloromethane (30 mL) Yield 35% (0.42 g). Mp
155 °C. Anal. Calc. for C28H24S6Sn: C, 50.07; H, 3.60%. Found: C,
the appearance of bands in the Raman spectra (356–328 cmꢁ1
)
assignable to the tin–sulfur and tin–chloride stretching vibration
[19].
49.35; H, 3.87%. IR (CsI):
m = 3056, 2927, 1717, 1465, 1439, 1219,
1038, 771, 752 cmꢁ1. Raman (260 mW):
m = 3066, 2937, 1585,
1567, 1223, 1199, 1030, 817, 663, 328, 245 cmꢁ1. NMR: 119Sn
(CDCl3) d = ꢁ95.8; 1H (CDCl3) d = 7.29
d
[1H, H-3, JH3–
3.4. NMR spectra
3
H4 = 7.32 Hz], d = 7.23 m [1H, H-4], d = 7.16 m [2H, H-5, H-6],
[2H, H-1, JH1—119 ¼ 82:4 Hz]; 13C{1H} (CDCl3):
NMR spectra of all compounds were recorded in CDCl3 solutions
at 25 °C; the assignment of the signals was carried out by the
3
d = 4.10
s
Sn
d = 142.8 (C7), 133.8 (C2), 133.5 (C6), 130.0 (C3), 128.7 (C5),

D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
371
i
ii
iii
iv
D
D
D
D
D(C6H5)2
OH HO
Br Br
SH HS
S
S
Sn
R1
R2
D
D
D
O 2a
O 3a
O 1a
4 - 7
S
2b
S
3b
S
1b
D
R1
R2
Ph
Cl
Cl
D
R1
R2
Ph
Cl
Cl
Ph
4a
5a
6a
7a
Ph
4b
5b
6b
7b
O
Ph
S
Ph
n-Bu
n-Bu
spiro
spiro
Scheme 2. Synthesis of compounds 4–7. (i) n-BuLi/(CH2O)n/THF; (ii) HBr/toluene; (iii) Thiourea/KOH/H+; (iv) RnSnCl4ꢁn/DABCO/CHCl3.
heteronuclear and homonuclear correlation of two dimensional
experiments (HSQC and HMBC). In solution, the DC6H4CH2S moie-
ties are equivalent for all compounds. For the organic compounds
1–3, the signals of the aromatic protons of the ligand framework
were observed as an ABCD pattern. The –CH2–X hydrogen reso-
nances were observed around 4.75–3.83 ppm; in the case of the
dithioligands 3a and 3b (X = SH) these CH2 signals were observed
the transannular interaction in 4–7 is practically absent in solution.
Nevertheless, some additional comments with respect to the 119Sn
chemical shifts of the chloromonophenyltin compounds 5a and 5b
can be done: (i) they occur at lower frequencies than the corre-
sponding shifts of the diphenyltin compounds 4a and 4b due to
the enhanced Lewis acidity over the tin atom and, (ii) they are also
more shifted than the chloromonobutyltin compounds 6a and 6b
as doublets due to the coupling with the –SH group observed as
[Dd = 55.9(2) ppm, low frequency] due to the nature of the phenyl
1
a triplet at ca. 2.0 ppm (3J1 H = 8.06 for 3a and 7.81 Hz for 3b).
group and its diamagnetic ring-current; a similar behavior was ob-
served in the corresponding chloromonophenyl and -butyl [{D(CH2
CH2S)2}SnRCl] stannocanes (D = O, S; R = Ph, n-Bu) [22,23]. In gen-
H–
However, these couplings vanished when the ligand was coordi-
119
1
nated with the starting material of tin and new 3J
Sn–
H
couplings –CH2–S–Sn appeared ranging from 55 Hz (for the diphe-
nyltin compound 4b) to 94 Hz (for the chlorotin compound 5b).
The coupling of these –CH2–S hydrogen nuclei with the aromatic
framework is practically absent making, therefore, the analysis of
the signals easier than that carried out in the more flexible stanno-
cane compounds of the type I with A = Sn. This situation allowed us
to explore the magnetic environmental changes in our compounds
after tin was bonded to sulfur. Hence, two different values of 3J
eral, the Dd values suggest significant changes in the coordination
number of tin and should be considered in addition to the values of
the 119Sn NMR chemical shifts.
3.5. Description of the solid state structures of dithiastannecines
The solid state molecular structures of 1a, 5a, 5b, 6a, 6b, and 7a
were determined by single crystal X-ray diffraction analyses. The
asymmetric unit of the compounds 5a and 5b contains two crystal-
lographically independent molecules (herein after labeled as 5a0 and
5a00 and 5b0 and 5b00, respectively). The molecular drawings are
depicted in Figs. 1–6 and selected bond lengths, angles, and torsion
angles for tin compounds 5a, 5b, 6a, 6b, and 7a are given in Table 2.
In the course of the synthesis the starting material 1a was crys-
tallized; the most relevant features in the structure are the angles
C–O–C [117.1(3)°] and that between the two twisted benzenic
planes [86.8(1)°]. The two –OH groups are pointed away from
the oxygen ether-type; the crystal structure is stabilized by hydro-
gen bonding with the hydroxyl groups (Fig. 1).
119
Sn–
1
couplings for the CH2–S–Sn system were observed: one
H
ranging from 55 to 61 Hz and the other one from 80 to 94 Hz.
The first range is associated with the diphenyltin compounds
[{D(C6H4CH2S)2}SnPh2] 4a (D = O) and 4b (D = S). The second one
is associated with the chloromonoorganotin compounds 5a–6b;
these greater values can be related to the enhanced Lewis acidity
over the tin atom. This acidity is expected because of the presence
of the electronegative chloro ligand, promoting the presence of a
transannular Dꢀ ꢀ ꢀSn interaction.
The 119Sn NMR spectra of the 4–7 tin compounds recorded in
the non-coordinating solvent CDCl3 at room temperature displayed
only a sharp signal in the ꢁ42 to 125 ppm range (Table 1) without
a clear pattern. Generally, it is well known that the 119Sn chemical
shifts move to lower frequencies when the coordination number
increases, even though the shifting is somewhat dependent on
the nature of the substituents attached to tin [20,21]. Thus, accord-
ing to Otera’s ranges [20], all the tin complexes would be four-
coordinate, indicating that the {D(C6H4CH2S)2}2ꢁ ligand is coordi-
nated to the tin atom in a bidentate fashion, i.e., the presence of
3.5.1. Description of the structures of 5a, 5b, 6a, and 6b
The analogous monoorganotin compounds [{D(C6H4CH2S)2}
SnRCl] 5a (D = O; R = Ph), 5b (D = S; R = Ph), 6a (D = O; R = n-Bu),
and 6b (D = S; R = n-Bu) are isostructural and contain a 10-mem-
bered central ring; although the 119Sn NMR data in solution sug-
gest a four coordinated structures in solution, the molecular
structures reveal five-coordinate tin atoms due to a transannular
coordination by the D donor atom. The local geometry around
the tin atom can be described as distorted trigonal bipyramidal
where two equatorial bonds are formed with the thiolate-type sul-
fur atoms and the third one with the carbon of either Ph or n-Bu
groups; the chloro and the donor D atoms occupy the axial posi-
tions. For the compounds, the Sn–S(thiolate-like) distances are in
good agreement with those reported for eight-membered
Table 1
119Sn{1H} NMR data (ppm) for compounds 4–7 in CDCl3 solution (25 °C).
D
4
5
6
7
O
S
33.6
37.5
19.5
ꢁ42.5
75.6
13.2
125.4
95.8

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D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
(18), 3.0799(18), 2.7126(14), and 3.0970(7) Å for 5a0, 5a00, 5b0,
5b00, 6a, and 6b, respectively; these distances are 78.3%, 80.7%,
74.4%, 77.6%, 73.5%, and 78.0% of the corresponding van der Waals
radii sum [RrvdW (Sn, D); D = O, 3.69 Å; D = S, 3.97 Å] [33] and they
influence the local geometry along the path from tetrahedral to tri-
gonal bipyramidal. By considering several dithiotin compounds
containing eight-membered rings where the coordination number
of the tin acceptor atom is four or five1, it is possible to observe that
the magnitude of the angle S–Sn–S is roughly coupled with the
transannular interaction Dꢀ ꢀ ꢀSn (D = O, S). The variability of these
structural parameters is illustrated in Fig. 7; the corresponding
parameters for 5a0, 5a00, 5b0, 5b00, 6a, and 6b were also plotted for
reasons of comparison.
From the scattergram it can be observed that the larger endocy-
clic S–Sn–S angle makes a shorter transannular distance. In spite of
the greater size and flexibility of the compounds 5a0, 5a00, 5b0, 5b00,
6a, and 6b, it can be noted that the S–Sn–S angle is also enlarged by
the presence of the transannular interaction. Thus, in order to eval-
uate distortions in geometry at the tin atom and the magnitude of
the interaction, the difference between the sum of the equatorial
Fig. 1. Hydrogen bonding in compound 1a. Selected bond lengths (Å): O(1)–C(7),
1.400(4); O(1)–C(8), 1.402(4); O(2)–C(1), 1.400(5); O(3)–C(14), 1.426(5)
O(3)ꢀ ꢀ ꢀO(2A), 2.669(4). Selected bond angles and torsion angles (°): C(7)–O(1)–
C(8), 117.1(3); O(2)–C(1)–C(2)–C(7), ꢁ178.6(3); C(8)–C(13)–C(14)–O(3), 174.8(3).
and axial angles [
D
=
R
(h)equatorial
ꢁ
R(h)axial] [19,24] and the Paul-
ing-type Bond Order based on interatomic distances [34,27],
respectively, were used. The data are listed in Table 3; the data
for the corresponding [{D(CH2CH2S)2}SnRCl] stannocanes (D = O,
S; R = Ph, n-Bu) are also presented.
heterocycles and several other compounds with tin–sulfur bonds
[22,24–32]. The Dꢀ ꢀ ꢀSn distances are 2.888(2), 2.978(2), 2.9522
Fig. 2. Molecular structure of 5a0 (left) and 5a00 (right). ORTEP at 50% probability. Selected torsion angles (°): C(7)–C(2)–C(1)–S(1), 83.6(4); C(8)–C(13)–C(14)–S(2), 79.0(4);
C(27)–C(22)–C(21)–S(3), ꢁ78.7(4); C(28)–C(33)–C(34)–S(4), ꢁ83.9(4).
Fig. 3. Molecular structure of 5b0 (left) and 5b00 (right). ORTEP at 50% probability. Selected torsion angles (°): C(7)–C(2)–C(1)–S(1), ꢁ81.3(8); C(8)–C(13)–C(14)–S(2), ꢁ82.1(7);
C(27)–C(22)–C(21)–S(4), 81.2(7); C(28)–C(33)–C(34)–S(5), 81.6(8).

D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
373
3.5.2. Description of the structure of 7a
The molecular structure of the spiro compound 7a shows a tin
atom covalently bonded to four sulfur atoms; in addition, two
intramolecular interactions of both oxygen atoms with the central
atom can be observed [Oꢀ ꢀ ꢀSn distances; 3.3106(17) and
3.3477(18) Å]. These distances are 89.7 and 90.7% of the
RrvdW(Sn,
O) sum (3.69 Å). The S–Sn–S angles are slightly distorted from the
ideal tetrahedral value; the most deviated one is the angle between
sulfurs S1 and S3 [100.21(2)°]. Moreover, these atoms and the two
oxygen atoms are almost coplanar (mean deviation: 0.0578 Å).
Hence, in order to assign the local geometry of the tin atom, we re-
lated the four covalent bonds plus the two short contacts to a
method used to describe structural displacements of six-coordi-
nate atoms between octahedral and bicapped tetrahedral idealized
geometries. [35] Thus, by using the sum of the fifteen angles of a
six-coordinate atom in an octahedron (1,620.00°) and in a bicapped
tetrahedron (1549.47°) we observed for 7a a value of 1549.94°,
corresponding to 99.3% of a bicapped tetrahedral geometry. With
respect to the Pauling-type bond order [27,34], an averaged
BO = 0.0211 for 7a was calculated, which is one order of magnitude
lower than that found for 5a, 5b, 6a, and 6b (Table 3). Therefore,
we can conclude that the transannular interaction distorts the
geometry of the tin atom, although is not as strong as that ob-
served in the [{D(C6H4CH2S)2}SnRCl] compounds.
Fig. 4. Molecular structure of compound 6a. ORTEP at 50% probability. Selected
torsion angles (°): C(7)–C(2)–C(1)–S(1), ꢁ76.3(2); C(8)–C(13)–C(14)–S(2), ꢁ83.4(2).
3.6. Theoretical study
The analogous compounds 6a and 6b are suitable systems to
study the nature of the intramolecular interactions (Dꢀ ꢀ ꢀSn), hence,
we present here the results of our theoretical results. Firstly, the
molecular systems were optimized, and the nature of the chemical
bonding was analyzed in terms of the topology of the electronic
density [q(r)]. All calculations were performed with the help of
the Amsterdam Density Functional (ADF) package [36–38] and
the suite of programs in GAUSSIAN 09 [39]. The ground-state wave-
function was used for the calculation of ‘‘atoms in molecules’’
(AIM) [40] to determine bond critical points (BCPs) and ring critical
points (RCPs); the results were analyzed in terms of electron den-
Fig. 5. Molecular structure of compound 6b. ORTEP at 50% probability. Selected
torsion angles (°): C(7)–C(2)–C(1)–S(1), 81.1(3); C(8)–C(13)–C(14)–S(2), 78.5(3).
sities,
q
, and their Laplacians,
r
2q. The Bader theory is imple-
mented in the AIM 2000 program [41].
Calculations of the compounds 6a and 6b were carried out by
using Amsterdam Density Functional (ADF) 2008.01. Scalar Relativ-
istic corrections were included via the ZORA to the Dirac equation
[42,43]. The geometry optimization in gas phase was worked out
using the Vosko–Wilk–Nusair functional. [44] The quadruple f qual-
ity with four polarization functions (QZ4P) basis of Slater-type orbi-
tals provided with the ADF package was used for all atoms. Selected
bond lengths and angles of the optimized structures are presented in
Table 4, showing that the calculations at the level employed repro-
duce adequately the experimental overall geometries, mainly in
the distances and angles parameters around the tin atom.
For the optimized system, the bond critical points of the elec-
tron density (BCPs) and the gradient paths were determined using
the AIM program. The results of the topological analysis of the elec-
tron density are presented in Table 5 and the molecular graphs are
depicted in Fig. 8 for compounds 6a and 6b.
Fig. 6. Molecular structure of compound 7a. ORTEP at 50% probability. Selected
torsion angles (°): C(7)–C(2)–C(1)–S(1), ꢁ79.1(3); C(8)–C(13)–C(14)–S(2), ꢁ90.2(3);
C(21)–C(16)–C(15)–S(3), 88.5(3); C(22)–C(27)–C(28)–S(4), 76.5(3).
The molecular graphs show that the BCP’s are present along with
the Snꢀ ꢀ ꢀD directions (D = O, S). The values of qc (Dꢀ ꢀ ꢀSn) are the
smallest (ꢂ0.021 a.u.) and
r
2qc is positive (in the table it is shown
The tbp % and bond orders are bigger for the stannocanes; how-
ever, the Dꢀ ꢀ ꢀSn–Cl angle is substantially larger for the 10-mem-
bered dithiastannecine compounds; this result is indicative of the
abilities of the {D(C6H4CH2S)2}2ꢁ ligand to expand the coordination
number of a central atom, especially if the Lewis acidity is greatly
enhanced.
1
Data for stannocane structures were retrieved from the CSD (version 5.32,
November 2010) with CSD codes CLOXSN, CLTHSN, COVQAF, COVQEJ, CXTHSN,
DELWIA, DELXAT, KISDUL, LIHRUP, LIHSAW, LIHSEA, LIHSIE, MAXTOU, MAXTUA,
PHOXSN, PHTHSN, XUYFIG, XUYFIG, YIFKON, YIFKUT, YIFLAA, YIFLEE, YIFLOO,
YIFLUU; the deposition numbers of dibenzostannocine structures are 756927,
756928, 756929, 756930, 756931.

374
D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
Table 2
Selected bond lengths (Å) and bond angles (°) of 5a, 5b (both display two crystallographic independent molecules), 6a, 6b and 7a.
5a0
5a00
5b0
5b00
6a
6b
7a
D
O(1)
S(1)
S(2)
Cl(1)
O(2)
S(3)
S(4)
Cl(2)
S(3)
S(1)
S(2)
Cl(1)
S(6)
S(4)
S(5)
Cl(2)
O(1)
S(1)
S(2)
Cl(1)
S(3)
S(1)
S(2)
Cl(1)
O(1)
S(1)
S(2)
S(3)
S1
S2
R1
R2
C(15)
C(35)
C(15)
C(35)
C(15)
C(15)
S(4)
Sn–S1
2.3886(9)
2.3803(10)
2.3709(10)
2.115(3)
2.888(2)
–
116.5(2)
–
–
116.15(3)
97.69(3)
117.86(10)
97.70(4)
116.90(10)
104.91(9)
176.92(5)
–
2.3812(10)
2.3898(10)
2.3575(10)
2.123(3)
2.978(2)
–
2.4034(18)
2.3970(17)
2.4000(18)
2.106(6)
2.9522(18)
–
105.9(3)
–
–
117.27(6)
93.17(6)
121.10(17)
96.15(6)
117.44(17)
101.11(17)
175.29(5)
–
2.3980(18)
2.3974(19)
2.384(2)
2.114(7)
3.0799(18)
–
2.3810(6)
2.3944(6)
2.3826(6)
2.146(2)
2.7126(14)
–
118.99(16)
–
–
116.09(2)
97.44(2)
115.66(6)
91.53(2)
122.87(6)
104.19(6)
175.20(4)
–
2.3993(7)
2.3829(7)
2.4132(7)
2.150(3)
3.0970(7)
–
102.50(12)
–
–
114.40(2)
96.29(3)
120.96(8)
93.91(2)
119.46(8)
102.29(8)
175.81(2)
–
2.3914(7)
2.3944(7)
2.4011(7)
2.3987(6)
3.3477(18)
3.3106(17)
116.39(19)
–
117.48(19)
114.47(2)
100.21(2)
110.95(2)
111.94(2)
111.28(2)
107.30(2)
168.66(3)
178.66(3)
Sn–S2
Sn–R1
Sn–R2
Dꢀ ꢀ ꢀSn
O(2)ꢀ ꢀ ꢀSn
C(7)–D–C(8)
C(27)–D–C(28)
C(21)–O(2)–C(22)
S1–Sn–S2
S1–Sn–R1
S1–Sn–R2
S2–Sn–R1
S2–Sn–R2
R1–Sn–R2
Dꢀ ꢀ ꢀSn–R1
O(2)ꢀ ꢀ ꢀSn–S(1)
–
–
116.0(3)
–
103.3(3)
–
114.67(3)
100.73(4)
114.22(10)
96.50(4)
119.34(10)
107.36(9)
178.06(5)
–
116.82(6)
96.67(7)
117.80(19)
96.43(7)
117.51(19)
105.05(19)
177.94(6)
–
Fig. 7. Scattergram of transannular distance Dꢀ ꢀ ꢀSn (Å) as a function of the S–Sn–S angle (°) for dithiotin compounds (numbers in parentheses indicate the size of the central
ring).
Table 3
Comparison of geometrical bond parameters in the dithiastannecine compounds [{D(C6H4CH2S)2}SnRCl] and [{D(CH2CH2S)2}SnRCl] stannocanes (D = O, S; R = Ph, n-Bu).
a
R
D
Dꢀ ꢀ ꢀSn(Å)
Dꢀ ꢀ ꢀSn–Cl (°)
tbp (%)
BOb Dꢀ ꢀ ꢀSn
5a0
Ph
Ph
Ph
Ph
n-Bu
n-Bu
Ph
Ph
n-Bu
n-Bu
O
O
S
S
O
S
O
S
O
S
2.888(2)
2.978(2)
2.9522(18)
3.0799(18)
2.7126(14)
3.0970(7)
2.412
2.805
2.409
2.786
176.92(5)
178.06(5)
175.29(5)
177.94(6)
175.20(4)
175.81(2)
167.33
174.24
169.72
170.23
56.2
48.6
72.6
60.0
68.3
69.3
69.6
81.4
69.1
83.5
0.0882
0.0658
0.1835
0.1212
0.1558
0.1147
0.4135
0.2960
0.4176
0.3148
5a00
5b0
5b00
6a
6b
[{D(CH2CH2S)2}SnRCl]
[{D(CH2CH2S)2}SnRCl]
[{D(CH2CH2S)2}SnRCl]
[{D(CH2CH2S)2}SnRCl]
a
Following the method of differences in angles
D
=
R
(h)equatorial
ꢁ
R(h)axial.
b
D
Method of calculation BO = 10ꢁ(1.41 d), where
D
d = dexp
ꢁ
R
rcov, according to the covalent radii sum
R
rcov(Sn, O) = 2.14 Å and
R
rcov(Sn, S) = 2.43 Å.

D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
375
Table 4
Table 5
Selected bond lengths (Å) and bond angles (°) of 6a and 6b.
Topological analysis of the electronic density for compounds 6a and 6b;
q
and L are
the density and the Laplacian (ꢁ1/4r2q), respectively. All quantities are in atomic
[{O(C6H4CH2S)2}Sn(n-Bu)Cl]
(6a)
[{S(C6H4CH2S)2}Sn(n-Bu)Cl]
(6b)
units.
6a (D = O)
6b (D = S)
Exp.
2.7126(14)
Calc.
2.881
Exp.
Calc.
3.030
q
L
q
L
Dꢀ ꢀ ꢀSn
Sn–Cl
Sn–S1
Sn–S2
Sn–C15
S1–Sn–C15 115.66(6)
S2–Sn–S1 116.09(2)
C15–Sn–S2 122.87(2)
Dꢀ ꢀ ꢀSn–Cl 175.20(4)
3.0970(7)
2.3826(6)
2.3810(6)
2.3944(6)
2.146(2)
2.351
2.405
2.398
2.142
2.4132(7)
2.3993(7)
2.3829(7)
2.150(3)
2.372
2.411
2.411
2.148
Dꢀ ꢀ ꢀSn1
Sn1–S1
Sn1–S2
Sn1–C15
Sn1–Cl1
C1–S1
C1–C2
C2–C7
C7–D
D-C8
C8–C13
C13–C14
C14–S2
H1A–H16A
Cl1–H16B
0.017
0.082
0.082
0.104
0.078
0.168
0.266
0.314
0.269
0.267
0.317
0.266
0.170
0.005
–
ꢁ0.014
ꢁ0.026
ꢁ0.025
ꢁ0.027
ꢁ0.046
0.056
0.183
0.245
0.061
0.067
0.248
0.182
0.056
ꢁ0.005
–
0.026
0.080
0.080
0.102
0.075
0.169
0.266
0.308
0.197
0.199
0.308
0.266
0.171
–
ꢁ0.014
ꢁ0.025
ꢁ0.025
ꢁ0.026
ꢁ0.044
0.056
0.183
0.234
0.090
0.093
0.234
0.184
0.059
–
112.3
120.96(8)
116.0
114.5
123.3
178.3
114.40(2)
119.46(2)
175.81(2)
116.3
123.9
178.7
as L = ꢁ0.014 a.u.). It is important to note that the L values of all bond
critical points connecting Sn with their neighbors are negative, rang-
ing from ꢁ0.014 to ꢁ0.046 a.u.; they are indicative of an important
ionic contribution. The topological analyses presented allow us to
classify as intramolecular donor–acceptor compounds, in which Sn
acts as an acceptor and the D atom as a donor (D = O, S).
0.009
-0.008
bit a five-coordinate tin atom where the local geometry is de-
scribed as a distorted trigonal bypyramidal. In all cases the
organic R group is located at an equatorial position, and the chloro
ligand occupies an axial position; the remaining axial position is
occupied by the D donor atom. In contrast, in solution the 119Sn
NMR experiments indicate the presence of a four-coordinate con-
figuration around the tin atoms despite the significant change in
4. Conclusion
The dithiastannecine compounds containing a 10-membered
central ring shows that the dithioligands are able to expand the
coordination number of the Sn acceptor atom by establishing the
interaction Dꢀ ꢀ ꢀSn (D = O or S). For example, the spirocyclic com-
pound 7a displays a bicapped tetrahedral local geometry where
the oxygen atoms cap two triangular faces; furthermore, the com-
pounds [{D(C6H4CH2S)2}SnRCl] 5a (D = O, R = Ph), 5b (D = S, R = Ph),
6a (D = O, R = n-Bu), and 6b (D = S, R = n-Bu) in the solid state exhi-
D
d values related to the coordination number of the tin atom,
mainly in compounds 5 where the acidity of Sn has been enhanced.
The DFT studies of 6a and 6b in gas phase satisfactorily reproduced
the overall geometries observed in the solid state; the topological
analysis showed bond critical points along the Dꢀ ꢀ ꢀSn interaction
Fig. 8. Critical points of the electron density (CPs) and the gradient paths in the compounds 6a and 6b (the small red and yellow spheres are the bond and ring critical points,
respectively). Color online.

376
D. Martínez-Otero et al. / Polyhedron 33 (2012) 367–377
Table 6
Selected crystallographic data for compounds 1a, 5a, 5b, 6a, 6b, and 7a.
1a
5a
5b
6a
6b
7a
Empirical formula
Formula weight
Temperature (K)
Crystal system
Space group
C
14H14O3
C20H17ClOS2Sn
491.60
131(2)
monoclinic
P21/c
C20H17ClS3Sn
507.66
131(2)
monoclinic
P21/c
C18H21ClOS2Sn
471.61
131(2)
orthorhombic
P212121
C18H21ClS3Sn
487.67
131(2)
monoclinic
P21/c
C28H24O2S4Sn
639.40
131(2)
monoclinic
P21/n
230.25
295(2)
orthorhombic
Pbcn
a (Å)
b (Å)
c (Å)
16.300(5)
7.533(2)
19.603(6)
90
2406.8(13)
8
28.8979(8)
9.09834(19)
15.2309(4)
102.836(3)
3904.48(17)
8
28.8866(14)
8.9857(5)
15.9723(7)
103.249(5)
4035.5(4)
8
10.3068(2)
12.8059(2)
14.7505(3)
90
1946.89(6)
4
9.1362(3)
24.7690(12)
8.7296(3)
96.515(3)
1962.70(14)
4
10.3756(3)
15.9807(5)
16.6493(5)
107.803(3)
2628.43(14
4
b (°)
V (Å3)
Z
Wavelength (Å)
Absorption coefficient (mmꢁ1
F(000)
0.71073
0.089
976
0.71073
1.665
1952
1.54184
14.186
2016
0.71073
1.665
944
0.71073
1.754
976
0.71073
1.315
1288
)
h range for data collection (°)
Reflections collected
Independent reflections
Completeness to h
Data/restrains/parameters
Goodness-of-fit on F2
2.08–24.06
17455
1914
99.9
1914/0/158
1.010
3.49–26.05
28270
7703
99.7
7703/0/451
1.050
4.72–68.12
26328
7366
100.0
7366/0/451
1.037
3.47–26.06
15082
3849
99.6
3849/0/209
1.026
3.17–25.29
8690
3567
99.8
3567/0/209
1.151
3.28–25.29
8769
4668
97.5
4668/0/316
0.987
Final R indices [I > 2
r
(I)]
R1 = 0.0596,
wR2 = 0.1572
R1 = 0.1199,
wR2 = 0.1943
0.334 and ꢁ0.183
R1 = 0.0344,
wR2 = 0.0631
R1 = 0.0514,
wR2 = 0.0665
0.438 and ꢁ0.614
R1 = 0.0473,
wR2 = 0.1044
R1 = 0.0797,
wR2 = 0.1160
0.826 and ꢁ0.707
R1 = 0.0169,
wR2 = 0.0348
R1 = 0.0187,
wR2 = 0.0352
0.202 and ꢁ0.379
R1 = 0.0225,
wR2 = 0.0520
R1 = 0.0267,
wR2 = 0.0531
0.347 and ꢁ0.580
R1 = 0.0243,
wR2 = 0.0591
R1 = 0.0330,
wR2 = 0.0613
0.805 and ꢁ0.394
R indices (all data)
Largest difference in peak and
hole (e Åꢁ3
)
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and their Laplacian values indicated an important ionic contribu-
tion. These results allow us to propose the wide coordination abil-
ities of the {D(C6H4CH2S)2}2ꢁ ligand to increase the coordination
number of tin as an acceptor atom as other well studied ligands
that produce smaller central rings of the types I–III also do.
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CCDC 830555, 830556, 830554, 830557, 830559, and 830558
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