Novel room light-induced disproportionation reaction of organo-ditin and -dilead compounds with organic dichalcogenides: An efficient salt-free route to organo-tin and -lead chalcogenides

Article abstract of DOI:10.1039/b000309n

Disproportionation of organo-ditin and -dilead compounds (R₃M)₂ (M = Sn, Pb) with organic dichalcogenides (R'Z)₂ (Z = S, Se, Te) is efficiently promoted by room light to produce the corresponding organo-tin and -lead chalc

Full text of DOI:10.1039/b000309n

Novel room light-induced disproportionation reaction of organo-ditin and
-dilead compounds with organic dichalcogenides: an efficient salt-free route to
organo-tin and -lead chalcogenides
Farzad Mirzaei, Li-Biao Han and Masato Tanaka*
National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, Japan.
E-mail: mtanaka@home.nimc.go.jp
Received (in Cambridge, UK) 7th January 2000, Accepted 8th March 2000
Published on the Web 30th March 2000
Disproportionation of organo-ditin and -dilead compounds
(R3M)2 (M = Sn, Pb) with organic dichalcogenides (RAZ)2 (Z
= S, Se, Te) is efficiently promoted by room light to produce
the corresponding organo-tin and -lead chalcogenides
R3MZRA quantitatively.
In a typical experiment, an equimolar mixture of (PhS)2 and
(Me3Sn)2 in C6D6 (0.5 M) was placed in a Pyrex tube under
nitrogen and exposed to room light at 35 °C.6 As confirmed by
1H NMR spectroscopy, the starting materials were completely
consumed within 20 min and PhSSnMe3 was obtained quantita-
tively as the sole product. Irradiation was essential for this
disproportionation; a control experiment carried out in the dark
under similar conditions did not lead to PhSSnMe3 even after 2
h.7,8 The reaction proceeded equally well in other solvents such
as toluene and chloroform. Particularly noteworthy is that even
in the absence of the solvent, the reaction took place as
efficiently. Thus, a colourless liquid of analytically pure
PhSSnMe3 was obtained by simply stirring a heterogeneous
mixture of 10 mmol of (PhS)2 (2.18 g) and an equivalent
amount of (Me3Sn)2 (3.28 g) for 1 h at 35 °C in room light.
Table 1 demonstrates the wide applicability of the present
light-induced disproportionation reaction. Other aromatic dis-
Chalcogenides of heavier group 14 metals, R3MZRA (M =
heavier group 14 element; Z = chalcogen element) decompose
upon heating to give composite metal chalcogenides which are
useful for solar cells and other semiconductor applications.1,2
They are also useful reagents in organic synthesis.3 Conven-
tional synthetic routes generally involve troublesome stoichio-
metric salt elimination reactions of R3MX (X = halogen atom)
with alkali metal chalcogenides.3 However, the alkali metal
salts concomitantly formed can be a serious contaminant that
reduces the performance of the semiconductor materials derived
via the MOCVD process of these metal chalcogenides as
precursors.2 Thus, an alternative, clean and salt-free route to
R3MZRA is highly desirable. During an extended research on the
4
Pt-catalysed disproportionation of (ArS)2 with (SiCl3)2 we
accidentally came across a novel light-induced disproportiona-
tion.We disclose herein preliminary results of the light-induced
disproportionation reaction of organic dichalcogenides (RAZ)2
(Z = S, Se, Te; RA = alkyl, aryl) with organo-ditin and -dilead
compounds (R3M)2 (M = Sn, Pb) leading to R3MZRA in
excellent yields [eqn. (1)].5
ulfides
such
as
(4-MeC6H4S)2,
(4-ClC6H4S)2,
(2,4,5-Cl3C6H2S)2 and (2-pyS)2 all reacted efficiently with
(Me3Sn)2 to afford the corresponding trimethyltin sulfides in
quantitative yields. Primary aliphatic disulfides such as (BuS)2
reacted similarly. However, as the alkyl group became bulkier,
Table 1 Light-induced disproportionation of (R3M)2 (M = Sn, Pb) with (RAZ)2 (Z = S, Se, Te)a
Run
(RZ)2
(RA3M)2
t/h
Product
Yield (%)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19d
(PhS)2
(SnMe3)2
(SnMe3)2
(SnMe3)2
(SnMe3)2
(SnMe3)2
(SnMe3)2
(SnMe3)2
(SnMe3)2
(SnPh3)2
(SnPh3)2
(SnPh3)2
(SnPh3)2
(PbPh3)2
(PbPh3)2
(SnMe3)2
(SnPh3)2
(PbPh3)2
(SnMe3)2
(PbPh3)2
< 0.5
1.5
1.5
1.5
1.5
1.5
4
2.5
1.5
3
PhSSnMe3
quant.
quant.
quant.
quant.
quant.
quant.
60 (95)b
8
(4-MeC6H4S)2
(4-ClC6H4S)2
(2,4,5-Cl3C6H2S)2
(2-pyS)2
(BuS)2
(CyS)2
(ButS)2
(PhS)2
(4-ClC6H4S)2
(4-FC6H4S)2
(BuS)2
(PhS)2
(BuS)2
(PhSe)2
(PhSe)2
(PhSe)2
(PhTe)2
4-MeC6H4SSnMe3
4-ClC6H4SSnMe3
2,4,5-Cl3C6H2SSnMe3
2-pySSnMe3
BuSSnMe3
CySSnMe3
ButSSnMe3
PhSSnPh3
4-ClC6H4SSnPh3
4-FC6H4SSnPh3
BuSSnPh3
PhSPbPh3
BuSPbPh3
PhSeSnMe3
PhSeSnPh3
PhSePbPh3
PhTeSnMe3
PhTePbPh3
quant.
quant.
quant.
quant.
quant.
quant.
quant.
quant.
96c
1
2
3.5
6
< 0.5
1.5
1.5
9
93c
98c
(PhTe)2
3
a Unless otherwise stated, the reaction was performed as follows: 0.03–0.5 M benzene solution in a Pyrex tube irradiated with a 40 W fluorescent lamp at
35 °C. b Yields in parentheses obtained after 7 h reaction time.c Traces of decomposition products were also formed.d Irradiation with a 200 W tungsten lamp
at 50 °C.
DOI: 10.1039/b000309n
Chem. Commun., 2000, 657–658
This journal is © The Royal Society of Chemistry 2000
657

3 For reviews, see: D. A. Armitage, in The Silicon–Heteroatom Bond, ed.
S. Patai and Z. Rappoport, John Wiley and Sons, Chichester, 1991, pp.
213–243; Comprehensive Organometallic Chemistry II, ed. E. W. Abel,
F. G. A. Stone and G. Wilkinson, Pergamon, Oxford, 1995, vol. 2, pp.
34–37, 166–174, 293–296; Comprehensive Organometallic Chemistry,
ed. G. Wilkinson, F. G. A. Stone and E. W. Abel, Pergamon, Oxford,
1982, vol. 2, pp. 167–177, 443–447, 604–607. See also: Kosugi, T.
Ogata, M. Terada, H. Sano and T. Migita, Bull Chem. Soc. Jpn., 1985,
58, 3657; Y. Nishiyama, S. Aoyama and S. Hatanaka, Phosphorus,
Sulfur Silicon Relat. Elem., 1992, 67, 267; Y. Nishiyama, H. Ohashi, K.
Itoh and N. Sonoda, Chem. Lett., 1998, 159.
4 L.-B. Han and M. Tanaka, J. Am. Chem. Soc., 1998, 120, 8249.
5 Although photochemical disproportionation has not been documented,
thermal disproportionation between (Ph3Pb)2 and (PhS)2 in boiling
aqueous benzene was reported to afford Ph3PbSPh (60–76% yield);
L. C. Willemsens and G. J. van der Kerk, J. Organomet. Chem., 1968,
15, 117; P. L. Clarke and J. L. Wardell, J. Chem. Soc., Dalton Trans.,
1974, 190. Disproportionation reactions of R4E2 (E = P, As, Sb, Bi)
with dichalcogenides RA2Z2 (Z = S, Se, Te) are also known: R. S.
Dickson and K. D. Heazle, J. Organomet. Chem., 1995, 493, 189; W.
Uhl, M. Layh, G. Becker, K.-W. Klinkhammer and T. Hildenbrand,
Chem. Ber., 1992, 125, 1547; H. J. Breuning and S. Guelec, Z.
Naturforsch., Teil B, 1986, 41, 1387; A. J. Ashe III and E. G. Ludwig,
Jr., J. Organomet. Chem., 1986, 308, 289; W. W. du Mont, T.
Severengiz and H. J. Breuning, Z. Naturforsch., Teil B, 1983, 38,
1306.
6 Special irradiation apparatus is not necessary for the disproportionation
of (ArS)2 with (Me3Sn)2. Usually, mixing the two reagents in a flask
placed about 2 m under a 40 W fluorescent lamp at room temperature for
a few minutes leads to quantitative formation of the products. Only
when the reactivity was low, was irradiation with a 200 W tungsten lamp
performed.
7 PhSSnMe3 was found to be formed only in ca. 15% yield by heating a
benzene solution of (PhS)2 and (Me3Sn)2 at 80 °C for 2 h in the dark.
8 Neither (PhS)2 nor (Me3Sn)2 was detected by 1H NMR spectroscopy
when pure PhSSnMe3 in benzene was exposed to the room light at room
temperature, indicating the irreversibility of the disproportionation
reaction. Similar phenomena were observed for PhSeSnMe3 and
PhTeSnMe3, although decomposition of PhTeSnMe3 (conversion 30%)
to Ph2Te and (Me3Sn)2Te was found to have occurred after prolonged
irradiation (44 h) at room temperature.
the reaction proceeded more slowly; the completion of the
reaction between (CyS)2 and (Me3Sn)2 required > 7 h and the
formation of ButSSnMe3 in the reaction of (ButS)2 with
(Me3Sn)2 under similar reaction conditions was only marginal.
Although slower than (Me3Sn)2, (Ph3Sn)2 reacted with both
aromatic and aliphatic disulfides to produce the corresponding
triphenyltin sulfides in quantitative yields.
Similar disproportionation reactions did not take place with
disilanes such as (Me3Si)2, (MePh2Si)2, (Ph3Si)2 or (SiCl3)2
under the same conditions. Digermanes such as (Me3Ge)2,
(ClMe2Ge)2 and (Ph3Ge)2 did not react either. However, the
reactions of (Ph3Pb)2 with (PhS)2 and (BuS)2 proceeded
smoothly and quantitative yields of the products were obtained.
(PhSe)2 was as reactive as (PhS)2 in the above disproportiona-
tion reactions. Similar reactions with (PhTe)2 proceeded
relatively slowly,8 but ultimately afforded respectable yields.
(Bu3Sn)2 has no absorption maximum in the normal UV
region. However, its lmax at a wavelength < 215 nm displays
strong end absorption that tails to 250–260 nm.9 (Ph3Sn)2 and
(Ph3Pb)2 display absorption maxima in the UV region (lmax
248–260 nm for the former depending on the solvent and 294
nm for the latter).9 Diphenyl dichalcogenides also have
absorption maxima in the UV, near-UV or visible regions.10
Because of these absorptions, various reactions involving
ditins11 or dichalcogenides10 can very efficiently proceed under
photolytic conditions by irradiation with a sunlamp through
Pyrex.12 With these precedents in mind, we envisioned that the
present disproportionation reaction proceeds via a radical
mechanism as shown in Scheme 1.13 However, the initiation
step is uncertain at the present time since precedents suggest
that homolytic cleavage of both M–M11 and Z–Z10 bonds by
light is possible to initiate the reaction. In agreement with the
reactivity trends in other reactions of chalcogen-centered
radicals (S > Se > Te),10 the disproportionation of (PhTe)2
proceeded most sluggishly. The decreasing trends in the
reactivity of aliphatic disulfides, (BuS)2 > (CyS)2 > (ButS)2,
appear to suggest that steric factors of the chalcogen-centered
radicals also play an important role.14
9 W. Drenth, M. J. Janssen and G. J. M. van der Kerk, J. Organomet.
Chem., 1964, 2, 265.
10 UV absorption for (PhZ)2: (PhS)2, lmax 250 nm; (PhSe)2, lmax 330 nm;
(PhTe)2, lmax 406 nm. Radical additions of (PhZ)2 to unsaturated
carbon–carbon bonds under irradiation of visible light have been
studied. For examples, see: A. Ogawa, I. Ogawa, R. Obayashi, K.
Umezu, M. Doi and T. Hirao, J. Org. Chem., 1999, 64, 84; A. Ogawa,
R. Obayashi, H. Ine, Y. Tsuboi, N. Sonoda and T. Hirao, J. Org. Chem.,
1998, 63, 881; A. Ogawa, R. Obayashi, M. Doi, N. Sonoda and T. Hirao,
J. Org. Chem., 1998, 63, 4277.
Scheme 1
11 Irradiation with
a sunlamp through Pyrex efficiently promotes
In summary, a clean and salt-free route to single source
precursors for semiconductors has been presented and the
process does not require the use of the volatile organic solvents.
These features appear to meet the requirement for ‘green’
chemistry, which is of contemporary public concern.15
Financial support from the Japan Science and Technology
Corporation (JST) through the CREST (Core Research for
Evolutional Science and Technology) program and a post-
doctoral fellowship to F. M. are gratefully acknowledged.
(Bu3Sn)2-initiated radical chain reactions; see D. P. Curran, M.-H. Chen
and D. Kim, J. Am. Chem. Soc., 1989, 111, 6265.
12 Curran et al. have reported that Pyrex shows 1–2.5% transmittance at
250–260 nm, which allows homolytic cleavage of (Bu3Sn)2. See ref.
11.
13 In agreement with the radical mechanism, heating an equimolar mixture
of (Me3Sn)2 and (PhS)2 in C6D6 at 80 °C in the dark in the presence of
10 mol% of AIBN led to 95% conversion after 2 h, whereas the same
treatment in the absence of AIBN showed only 15% conversion.
·
14 (BuS)2 is reported to be 14 times more reactive toward Bu3Sn than
(ButS)2, see: J. Spanswick and K. U. Ingold, Int. J. Chem. Kinet., 1970,
2, 157.
Notes and references
1 G. A. Domrachev, V. K. Khamylov, M. Z. Bochkarev, B. V. Zhuk, B. S.
Kaverin, B. A. Nesterov and A. I. Kirillov, Ger. Pat., 2703873, 1977;
H. Uchida, Jpn. Pat., 01298010, 1989.
2 J. M. Fischer, W. E. Piers, S. D. P. Batchilder and M. J. Zaworotko,
J. Am. Chem. Soc., 1996, 118, 283 and references therein.
15 Note added at proof: We have found very recently that the December 20
issue of Chemical Abstracts has compiled a paper on a new method for
the synthesis of stannyl selenides; see V. A. Potapov, S. V. Amosova, V.
Svetlana, I. P. Beletskaya, A. A. Starkova, A. V. Martynov and L.
Hevesi, Sulfur Lett., 1999, 22, 237; Chem. Abstr., 1999, 131,
337113u.
658
Chem. Commun., 2000, 657–658