G. Prabusankar et al. / Journal of Organometallic Chemistry 693 (2008) 3383–3386
3385
The
g
1 bonding of the simply bonded sulfonate groups (S1, S2 and
1H NMR: d 0.27 (s, 9H, [47], Sn(CH3)3), 1.16 (d, 6H, p-CH(CH3)2),
1.21 (d, 12H, o-CH(CH3)2), 2.82 (sept, 1H, p-CH(CH3)2), 2.91 (sept,
2H, o-CH(CH3)2), 6.98 (s, 2H, [28], ArH). 13C NMR (CDCl3, 62.9): d
À4.0 (SnCH3)3), 24.5 (p-CH(CH3)2), 24.7 (o-CH(CH3)2), 34.7 (p-
CH(CH3)2), 37.0 [48] (o-CH(CH3)2), 121.5 [42] (C(Ar)H), 138.34
(C(Ar)Sn), 149.8 (C(Ar)p-CH(CH3)2), 156.2 [35] (C(Ar)o-CH(CH3)2).
119Sn NMR: d À62.4. A 3:1 mixture of SnCl4 (3.9 g, 15 mmol)
and 1 (1.7 g, 5 mmol) was heated in a Schlenk tube at 120 °C
for 5 h. Unreacted SnCl4 and MeSnCl3 by-product formed in the
reaction mixture were removed by vacuum distillation (50–
80 °C/0.01 mmHg). The resulted black solid was purified by vac-
uum distillation to give 2 as a colorless crystalline solid (130 °C/
1 Â 10À4 mmHg) (2 g, 92%). Mp: 113–115 °C; 1H NMR: d 1.17 (d,
6H, p-CH(CH3)2), 1.25 (d, 12H, o-CH(CH3)2), 2.83 (sept, 1H, p-
CH(CH3)2), 3.11 (sept, 2H, o-CH(CH3)2), 7.15 (s, 2H, [65], ArH).
13C NMR (CDCl3, 62.9): d 24.2 (p-CH(CH3)2), 25.2 (o-CH(CH3)2),
34.8 (p-CH(CH3)2), 38.6 [55] (o-CH(CH3)2), 124.3 [127] (C(Ar)H),
135.7 (C(Ar)Sn), 154.9 (C(Ar)p-CH(CH3)2), 150.0 [23] (C(Ar)o-
S4) can be easily recognized by the different bond lengths of sul-
fur–oxygen bonds, 1.505 Å (mean) for the sulfur–oxygen(tin)
bonds, and 1.439 Å (mean) for the sulfur–oxygen double bonds.
Both tin atoms are also linked by two oxygen atoms of a sulfonate
group (S3) in a bidentate coordination mode. The intramolecular
bridging g2l2 character is characterized by two almost identical
tin–oxygen bonds (2.169 and 2.158 Å) and sulfur–oxygen(tin)
bonds (1.494 and 1.505) as well as by a shorter sulfur oxygen dou-
ble bond (1.427 Å). The presence of monodentate or bridging
(intermolecular) bidentate sulfonate groups in organotin sulfo-
nates has been already reported, but never in the same molecule.
So, to the best of our knowledge, the simultaneous existence of a
monodentate mode and an intramolecular bridging bidentate
binding mode in an organotin sulfonate is reported here for the
first time. Another noteworthy feature is the presence of hydrogen
bonds. The hydrogen atoms of the hydroxide groups are intramo-
lecularly linked to oxygen atoms of equatorial sulfonate groups
(S1 and S4) through normal hydrogen bonding (1.852 and
1.969 Å) forming two six-membered rings. One hydrogen atom of
the coordinated water molecule is also bonded to the oxygen atom
of an axial sulfonate group (S2) (1.950 Å). The other hydrogen atom
of the coordinated water molecule ties the tetrahydrofuran solvate
to the tin core through an hydrogen bond (1.771 Å).
The monomeric molecules of 4 associated to THF are well sep-
arated in space, unlike other chloro- or sulfonatodihydrodioxadist-
annetanes. The last compounds form coordination polymer
networks that are built through coordination bonds between sulfo-
nate groups and tin atoms [11,13,15] or hydrogen bonds between
coordinated water and/or hydroxide and ligands [2–5,10,18]. In 4,
it is likely that the bulky organic ligands preclude close contacts
from one molecule to another. When compared to other anions
as carbonates, phosphates or phophinates, this example shows that
the weak aptitude of organosulfonates to build supramolecular
networks by cooperative coordination or weaker intermolecular
interactions [33,34] can even been suppressed.
CH(CH3)2). 119Sn NMR:
d
À93.5 ppm. An excess of propyne
(25 mmol) was condensed in toluene (50 mL) at À196 °C. At
À90 °C, n-BuLi (4 mmol) in toluene (40 mL) was added dropwise
to the above solution. Then the reaction mixture was slowly
brought to room temperature and stirred for 15 min. Again, the
reaction mixture was cooled to À90 °C and a solution of 2
(1.7 g, 4 mmol) in toluene (50 mL) was added dropwise. The reac-
tion mixture was slowly brought to RT and stirred for 12 h. Insol-
ubles were filtered through a MgSO4 bedded G3 frit and removal
of volatiles from the filtrate resulted in 3 in an excellent yield.
(1.6 g, 90%). Mp: 129–131 °C. 1H NMR: d 1.17 (d, 6H, p-CH(CH3)2),
1.22 (d, 12H, o-CH(CH3)2), 1.83 (s, 9H [15], C„CCH3), 2.79 (sept,
1H, p-CH(CH3)2), 3.37 (sept, 2H, o-CH(CH3)2), 6.97 (s, 2H, [31],
ArH). 13C NMR (CDCl3, 62.9): d 5.0 (C„CCH3), 23.8 (p-CH(CH3)2),
24.8 (o-CH(CH3)2), 34.2 (p-CH(CH3)2), 36.4 [48] (o-CH(CH3)2),
79.3 [850] (C„CCH3), 106.4 [176] (C„CCH3), 121.9 [72]
(C(Ar)H), 131.4 (C(Ar)Sn), 151.0 (C(Ar)p-CH(CH3)2), 155.6 [52]
(C(Ar)o-CH(CH3)2). 119Sn NMR: d À335.4 ppm. IR: 3043w, 2962s,
2930s, 2881s, 2169vs, 1589w, 1560w, 1463 m, 1423w, 1384w,
1362w, 1266w, 1101w, 996vs, 886w, 802w, 746w, 650w, 513w
cmÀ1. Anal. Calc. for C24H32Sn: C, 65.63; H, 7.34; Sn, 27.03. Found:
C, 65.25; H, 7.56; Sn, 26.59%.
In summary we have shown that a new tetrasulfonato-1,3-dihy-
dro-1,3-dioxa-2,4-diaryl-2,4-distannetane 4 was obtained as the
smallest discrete molecule from the hydrolysis of a bulky aryltri-
propynyltin in the presence of p-toluenesulfonic acid. Its crystal
structure revealed several unusual features such as the unsymmet-
rical substitution of tin atoms and the
linkages for the sulfonate groups.
g
1 and intramolecular g2l2
3.3. Synthesis of 4
To a stirred solution of 3 (1.8 g, 4 mmol) in THF (30 mL), H2O
(0.9 g, 49.2 mmol) was added dropwise at RT. The reaction mixture
was heated under reflux for 8 days and p-toluenesulfonic acid mono-
hydrate (0.8 g, 4 mmol) was added at once at RT. The resulting solu-
tion was then heated under reflux for 6 h. It was dried under reduced
pressure to give a white solid, whichwas dissolved in THF (2 mL) and
filtered to obtain colorless crystals of 4 at 10 °C. (0.98 g, 32%).
Mp > 180 °C (dec). 1H NMR (CDCl3, 250 MHz): d 1.12 (m, 36 H,
p-CH(CH3)2 and o-CH(CH3)2), 1.74 (m, 8H, THF), 2.27–2.28 (m, 12H,
O3SArCH3), 2.65–2.84 (m, 6H, p-CH(CH3)2 and o-CH(CH3)2), 3.63
(m, 8H, THF), 6.81–7.84 (m, 20H, ArH). 119Sn NMR (CDCl3,
3. Experimental
3.1. General remarks
All reactions were carried out under a nitrogen atmosphere. THF
and toluene were distilled from sodium-benzophenone ketyl prior
to use. Tin tetrachloride was distilled before use. 1H, 13C, and 119Sn
NMR spectra were recorded on a Bruker AC 200, AC 250, or DPX300
spectrometer (solvent CDCl3). Tin–hydrogen and tin–carbon cou-
pling constants are given in square brackets. Elemental analyses
were performed by the ‘‘Service d’Analyse du CNRS” at Vernaison,
France.
74.6 MHz): d À644.2, À676.2 ppm. IR(KBr):
m = 3403 s, 3207s,
3441s, 2961vs, 2864s, 1594w, 1563w, 1498w, 1464s, 1420m, 1385
m, 1364m, 1279s, 1153s, 1101vs, 1027s, 986vs, 877m, 838w, 814s,
788m, 742w, 708w, 680s, 568s cmÀ1. Anal. Calc. for C58H78O15S4Sn2,
1.5THF(1489.1):C, 51.62;H, 6.09;S, 8.61;Sn, 15.94. Found:C, 51.21;
H, 5.44; S, 8.23; Sn, 15.02%.
3.2. Synthesis of 3
An equimolar solution of arylmagnesium bromide (10 mmol)
in THF (60 mL) was treated with Me3SnCl (1.9 g, 10 mmol) in
THF (75 mL) at room temperature, stirred for 12 h and the reac-
tion mixture was quenched with a saturated solution of NH4Cl,
followed by extraction with hexane (200 mL). Evaporation of
the solvents gave 3.4 g of 1 as a white solid (93%). Mp: 86 °C.
3.4. Structure determination for 4
Crystal data collection and processing parameters are given in
Table 1. A suitable crystal was covered with mineral oil (Aldrich),
mounted onto glass fiber, and transferred directly to the 150-K