The First Phosphine-Catalyzed Insertion of Tellurium into Sn-Sn and Pb-Pb Bonds: A Simple and Efficient Route to R3MTeMR3 (M = Sn, Pb)

Article abstract of DOI:10.1021/om990728s

In the presence of a catalytic amount of a phosphine, elemental tellurium efficiently inserts into Sn-Sn and Pb-Pb bonds under mild conditions to give the corresponding tellurides R₃MTeMR₃ (M = Sn, Pb) in quantitative yield. Mechanistic study shows that first a phosphine telluride R′₃P=Te is formed via the reaction of R′₃P with tellurium, which subsequently reacts with (R₃M)₂ to produce (R₃M)₂Te and concomitantly regenerates R′₃P to restart another cycle of the catalytic insertion.

Full text of DOI:10.1021/om990728s

722
Organometallics 2000, 19, 722-724
Th e F ir st P h osp h in e-Ca ta lyzed In ser tion of Tellu r iu m
in to Sn -Sn a n d P b-P b Bon d s: A Sim p le a n d Efficien t
Rou te to R3MTeMR3 (M ) Sn , P b)
Li-Biao Han, Farzad Mirzaei, and Masato Tanaka*
National Institute of Materials and Chemical Research, Tsukuba, Ibaraki 305-8565, J apan
Received September 16, 1999
Summary: In the presence of a catalytic amount of a
phosphine, elemental tellurium efficiently inserts into
Sn-Sn and Pb-Pb bonds under mild conditions to give
the corresponding tellurides R3MTeMR3 (M ) Sn, Pb)
in quantitative yield. Mechanistic study shows that first
a phosphine telluride R′3PdTe is formed via the reaction
of R′3P with tellurium, which subsequently reacts with
(R3M)2 to produce (R3M)2Te and concomitantly regener-
ates R′3P to restart another cycle of the catalytic inser-
tion.
phosphine-catalyzed insertion of elemental tellurium
into Sn-Sn and Pb-Pb bonds.6 The products,
(R3M)2Te (M ) Sn, Pb), formed in quantitative yield,
are known as efficient low-temperature single-source
precursors to structurally defined narrow-band-gap
semiconductors.7
Great efficacy of phosphines is exemplified by the
following experiments. In a control experiment, an
equimolar mixture of (Me3Sn)2 (1 mmol, 328 mg) and
finely powdered tellurium (1 mmol, 128 mg) suspended
in benzene (10 mL) was stirred at room temperature
for 3 h. GC and 1H NMR analyses showed that no
detectable product had been formed and the starting
materials remaining unchanged. When a trace amount
of t-Bu3P (10 mg, 5 mol %) was added to the suspension,
however, the tellurium powder completely disappeared
within 3 h to afford (Me3Sn)2Te (1a ) as sole product in
quantitative yield (eq 1).8,9 Although heating was needed,
other distannanes such as (n-Bu3Sn)2 and (Ph3Sn)2
behaved similarly using either n-Bu3P or t-Bu3P as the
Technology to use tellurium-containing materials as
structurally defined single-source precursors in elec-
tronic, optic, and optoelectronic applications is rapidly
emerging.1 Accordingly, development of clean methods
for the synthesis of these materials starting with readily
available organotelluriums2 is a subject of current
scrutiny.3 The use of phosphine tellurides (R′3PdTe)4
as tellurium delivery agents in insertion reactions to a
variety of metal-metal and metal-carbon bonds has
attracted attention, and some novel tellurium com-
pounds have been prepared.5 However, all hitherto
known reactions require a stoichiometric quantity of
R′3PdTe, and hence an equimolar amount of PR′3 is
inevitably formed, which can be another drawback to
the purification of the resulting products.5c Moreover,
R′3PdTe usually are difficult to prepare and handle
because of their thermal instability and high air sen-
sitivity.4 Herein we disclose the first examples of the
(5) Selected examples: (a) Uhl, W.; Graupner, R.; Reuter, H. J .
Organomet. Chem. 1996, 523, 227. (b) Bollinger, J . C.; Ibers, J . A. Inorg.
Chem. 1995, 34, 1859. (c) Piers, W. E.; Macgillivray, L. R.; Zaworotko,
M. J . Organometallics 1993, 12, 4723. (d) Uhl, W.; Schuetz, U. Z.
Naturforsch. B 1994, 49, 931. (e) Steigerwald, M. L.; Siegrist, T.;
Gyorgy, E. M.; Hessen, B.; Kwon, Y.-U.; Tanzler, S. M. Inorg. Chem.
1994, 33, 3389. (f) Steigerwald, M. L.; Stuczynski, S. M.; Kwon, Y.-U.;
Vennos, D. A.; Brennan, J . G. Inorg. Chim. Acta 1993, 212, 219. (g)
Hessen, B.; Siegrist, T.; Palstra, T.; Tanzler, S. M.; Steigerwald, M. L.
Inorg. Chem. 1993, 32, 5165. (h) McConnachie, M. J .; Bollinger, J . C.;
Ibers, J . A. Inorg. Chem. 1993, 32, 3923. (i) Ma, A. L.; Thoden, J . B.;
Dahl, L. F. J . Chem. Soc., Chem. Commun. 1992, 1516. (j) Steigerwald,
M. L.; Siegrist, T.; Stuczynski, S. M.; Kwon, Y. U. J . Am. Chem. Soc.
1992, 114, 3155. (k) Von Windheim, J . A.; Cocivera, M. J . Phys. Chem.
Solids 1992, 53, 31. (l) Brennan, J . G.; Siegrist, T.; Stuczynski, S. M.;
Steigerwald, M. L. J . Am. Chem. Soc. 1990, 112, 9233. (m) Brennan,
J . G.; Siegrist, T.; Stuczynski, S. M.; Steigerwald, M. L. J . Am. Chem.
Soc. 1989, 111, 9240. (n) Steigerwald, M. L. Chem. Mater. 1989, 1, 52.
(o) Steigerwald, M. L.; Rice, C. E. J . Am. Chem. Soc. 1988, 110, 4228.
(p) Steigerwald, M. L.; Sprinkle, C. R. Organometallics 1988, 7, 245.
(6) The direct insertion reactions of elemental sulfur into Sn-Sn
and Pb-Pb bonds are known to give moderate yields of the corre-
sponding sulfides: (a) Kraus, C. A.; Sessions, W. V. J . Am. Chem. Soc.
1925, 47, 2361. (b) Vyazankin, N. S.; Bochkarov, M. N.; Sanina, L. P.
J . Gen. Chem. USSR 1966, 36, 1954. (c) Kuivila, H. G.; J akusik, E. R.
J . Org. Chem. 1961, 26, 1430. (d) Otera, J .; Kadowaki, T.; Okawara,
R. J . Organomet. Chem. 1969, 19, 213. (e) Krebs, A. W.; Henry, M. C.
J . Org. Chem. 1963, 28, 1911. (f) Willemsens, L. C.; Van der Kerk, G.
J . M. J . Organomet. Chem. 1968, 15, 117.
* Corresponding author. Fax: +81-298-614474. E-mail: mtanaka@
home.nimc.go.jp.
(1) (a) Strauss, A. J . In Concise Encyclopedia of Semiconducting
Materials and Related Technologies; Mahajan, S., Kimerlinf, L. C.,
Eds.; Pergamon: New York, 1992; p 427. (b) George, J .; Palson, T. I.
Thin Solid Films 1985, 127, 233, and references therein.
(2) For example: (a) Siemeling, U. Angew. Chem. 1993, 105, 70;
Angew. Chem., Int. Ed. Engl. 1993, 32, 67. (b) O’Brien, P. Chemtronics
1991, 5, 61. (c) Fischer, J . M.; Piers, W. E.; Batchilder, S. D. P.;
Zaworotko, M. J . J . Am. Chem. Soc. 1996, 118, 283, and references
therein.
(3) Alkali metal salts that are formed in the reactions of organic
halides with the corresponding tellurium anions such as LiTeR and
NaTeR can be impurities which seriously deteriorate the performance
of the resulting materials. General reviews on organotellurium chem-
istry: (a) Irgolic, K. Y. The Organic Chemistry of Tellurium; Gordon
and Breach: New York, 1974. (b) The Chemistry of Organic Selenium
and Tellurium Compounds; Patai, S., Rapport, Z., Eds.; J ohn Wiley &
Sons: New York, 1986; Vol. 1. Ibid. 1987; Vol. 2. (c) Comprehensive
Organometallic Chemistry II; Abel, E. W., Stone, F. G. A., Wilkinson,
G., Eds.; Pergamon: Oxford, U.K., 1995; Vol. 11, p 571. (d) Petragnani,
N. Tellurium in Organic Synthesis; Academic Press: London, 1994.
(7) (a) Boudjouk, P.; J arabek, B. R.; Simonson, D. L.; Seidler, D. J .;
Grier, D. G.; McCarthy, G. J .; Keller, L. P. Chem. Mater. 1998, 10,
2358. (b) Boudjouk, P.; Seidler, D. J .; Bahr, S. R.; McCarthy, G. J .
Chem. Mater. 1994, 6, 2108. (c) Boudjouk, P.; Seidler, D. J .; Grier, D.
G.; McCarthy, G. J . Chem. Mater. 1996, 8, 1189. (d) Seligson, A. L.;
Arnold, J . J . Am. Chem. Soc. 1993, 115, 8214.
(8) In the absence of a phosphine, the reaction of tellurium with
(Me3Sn)2 proceeded, albeit very sluggishly even at 80 °C, to give (Me3-
Sn)2Te in 34% yield after 24 h.
(4) (a) Zingaro, R. A.; Steeves, B. H.; Irgolic, K. J . Organomet. Chem.
1965, 4, 320. (b) duMont, W.-W. Angew. Chem. 1980, 92, 562; Angew.
Chem., Int. Ed. Engl. 1980, 19, 554. (c) J ones, C. H. W.; Sharma, R.
D. Organometallics 1987, 6, 1419. (d) Kuhn, N.; Henkel, G.; Schumann,
H.; Froehlich, R. Z. Naturforsch. B 1990, 45, 1010.
10.1021/om990728s CCC: $19.00 © 2000 American Chemical Society
Publication on Web 02/09/2000

Communications
Organometallics, Vol. 19, No. 5, 2000 723
Ta ble 1. P h osp h in e-Ca ta lyzed In ser tion of
Tellu r iu m in to Sn -Sn Bon d sa
Sch em e 2. Rea ction of Me6Sn 2 w ith R′3P dE in
Ben zen e-d 6 (0.4 M): 25 °C for E ) Te a n d 80 °C for
E ) Se
phosphine
(R3Sn)2
conditions
% yieldb
(4-ClC6H4)3P
Ph3P
(n-Bu)3P
(n-Bu)3P
(n-Bu)3P
(n-Bu)3P
(Me3Sn)2
(Me3Sn)2
(Me3Sn)2
(Me3Sn)2
(n-Bu3Sn)2
(Ph3Sn)2
80 °C, 3 h, 1 M
80 °C, 3 h, 1 M
80 °C, 0.5 h, 1 M
25 °C, 18 h, 1 M
80 °C, 3 h, 1 M
80 °C, 3 h, 0.1 M
80 °C, 5 h, 0.1 M
25 °C, 3 h, 0.1 M
80 °C, 2 h, 0.1 M
34
45
100
9
100
73
100
100
100
(t-Bu)3P
(t-Bu)3P
(Me3Sn)2
(Ph3Sn)2
a
All reactions were run in a Schlenk flask using equimolar Te
powder and (R3Sn)2 in C6D6 in the presence of 5 mol % phosphine
b
catalyst with stirring. Yields refer to NMR yields; since no other
product was found by NMR spectroscopy, the yield was evaluated
based on the integration of the signals arising from the product
and the starting distannane.
tellurium powder in benzene in the presence of 5 mol
% of t-Bu3P at 50 °C for 5 h.12,13
Sch em e 1. P r op osed Mech a n ism for th e
P h osp h in e-Ca ta lyzed In ser tion of Tellu r iu m in to
Sn -Sn Bon d s
5 mol% t-Bu3P
(Ph Pb) Te
96% yield
(Ph3Pb)2 + Te
8
(2)
3
2
benzene
50 °C, 5 h
Monitoring the progress of the Et3P-catalyzed reaction
of (Me3Sn)2 with tellurium by 1H NMR spectroscopy
clearly revealed that the catalysis involved two pro-
cesses, generation of Et3PdTe and its reaction with
(Me3Sn)2, with the second step being rate-determining
as far as trialkylphosphines are concerned (Scheme 1).
Thus, stirring a mixture of (Me3Sn)2 (0.1 mmol), Te
powder (0.1 mmol), and Et3P (0.05 mmol) in C6D6 (1 mL)
at room temperature for 5.5 h resulted in complete
consumption of Et3P to form Et3PdTe in quantitative
yield (based on Et3P) along with a trace of (Me3Sn)2Te
(11% based on the distannane). Upon heating the
reaction mixture at 80 °C for 3 h, a pale yellow
transparent solution was obtained, in which only (Me3-
Sn)2Te (∼0.1 mmol, ∼100% yield) and Et3P (∼100%
recovery) were detected, while Et3PdTe and (Me3Sn)2
had completely disappeared.
catalyst, and quantitative yields of the corresponding
distannyl tellurides were obtained (Table 1). Aromatic
phosphines such as Ph3P and (4-ClC6H4)3P also cata-
lyzed the reaction with somewhat low activity as
compared with n-Bu3P and t-Bu3P. For example, a 45%
yield of 1a was formed after 3 h heating when Ph3P was
employed as the catalyst. Among the phosphines
screened, t-Bu3P showed the highest catalytic activity,
followed by n-Bu3P, Ph3P, and (4-ClC6H4)3P, which
parallels their basicities.10
5 mol% PR′3
(R3Sn)2 + Te
8 (R3Sn)2Te
(1)
benzene
On the basis of the proposed mechanism, and as long
as the phosphine telluride is generated to a sufficient
extent, one can envision that the catalytic activity of
phosphines (Table 1) increases in parallel with the
reactivity of their corresponding phosphine tellurides
toward (R3Sn)2. Indeed, the yield of 1a in the reaction
of Et3PdTe with (Me3Sn)2 was only 56% even after
stirring for 22 h (Scheme 2), while a quantitative
formation of 1a was observed in only 1 h when
t-Bu3PdTe was employed.14 Since triarylphosphines
This phosphine-catalyzed insertion of tellurium could
be successfully extended to diplumbanes, efficiently
producing diplumbyl tellurides. As shown in eq 2, air
and moisture sensitive (Ph3Pb)2Te, which had been
prepared only in moderate yield via the reaction of
Ph3PbTeLi with Ph3PbCl,11 was obtained in high yield
simply by heating an equimolar mixture of (Ph3Pb)2 and
(9) Typical procedure for the preparation of distannyl tellurides:
Hexaphenyldistannane (280 mg, 0.400 mmol), tellurium powder (54
mg, 0.423 mmol), and t-Bu3P (4.0 mg, 0.02 mmol, 5 mol %) were placed
in a Schlenk tube under nitrogen atmosphere, and 4 mL of dry benzene
was added. The mixture was stirred at 80 °C for 5 h and was filtered
under nitrogen to remove excess tellurium. The solvent was evaporated
under reduced pressure, and the residue was washed with pentane to
give a white solid of analytically pure (Ph3Sn)2Te (331 mg, 100% yield).
White crystals could be obtained by recrystallization of the solid using
a CH2Cl2-pentane mixture (337 mg, 407 mmol, 81% yield). Mp: 157
°C (lit.16 149-150 °C). Anal. Calcd for C36H30Sn2Te: C, 52.24; H, 3.65.
Found: C, 52.58; H, 3.44. 1H NMR (500 MHz, C6D6): δ 7.44-7.45 (m,
12H, J HSn ) 55.7 Hz), 6.98-7.06 (m, 18H). 13C NMR (125 MHz, C6D6):
(12) It is important to run the reaction at lower temperatures to
prevent side reactions. For example, the reaction run at 80 °C
precipitated a black powder, presumably due to the formation of PbTe.
(13) Typical procedure for the preparation of diplumbyl tellurides:
Hexaphenyldiplumbane (2.631 g, 3 mmol), tellurium powder (396 mg,
3.1 mmol), and t-Bu3P (30 mg, 0.15 mmol, 5 mol %) were placed in a
Schlenk tube under nitrogen atmosphere, and 15 mL of dry benzene
was added. The mixture was stirred at 50 °C for 5 h and was filtered
(under nitrogen) to remove excess tellurium. Solvent was evaporated
under reduced pressure, and the residue was washed with pentane to
give a yellow solid of spectroscopically pure (Ph3Pb)2Te (2.893 g, 96%
yield), as confirmed by 1H and 13C NMR spectroscopies. Bright yellow
crystals of (Ph3Pb)2Te were obtained by recrystallization from a CH2-
Cl2-pentane mixture, 2.20 g, 73% yield. Mp: 137 °C (lit.11 128-129
°C). Anal. Calcd for C36H30Pb2Te: C, 43.04; H, 3.01. Found: C, 43.37;
H, 2.80. 1H NMR (500 MHz, C6D6): δ 7.06-7.08 (m, 12H, J HPb ) 93.5
δ 138.6, 137.1 (J CSn ) 44.5 Hz), 129.5 (J CSn ) 12.4 Hz), 128.9 (J CSn
)
56.9 Hz). 119Sn NMR (186 MHz, C6D6, Me4Sn): δ -140.2. 125Te NMR
117SnTe
119SnTe
)
(157 MHz, CDCl3, Me2Te): δ -1290.4 (J
) 3085.7 Hz, J
3226.1 Hz).
(10) Hudson, H. R. In The Chemistry of Organophosphorus Com-
pounds, Vol. 1; Hartley, F. R., Ed.; J ohn Wiley & Sons: New York,
1990; p 473.
(11) Schumann, H.; Thom, K.-F.; Schmidt, M. J . Organomet. Chem.
1965, 4, 28.
Hz), 6.67-6.59 (m, 18H). 13C NMR (125 MHz, C6D6): δ 150.8 (J CPb
)
396.2 Hz), 137.3 (J CPb ) 77.6 Hz), 129.8 (J CPb ) 85.8 Hz), 128.9
(J CPb ) 19.6 Hz). 125Te NMR (157 MHz, C6D6, Me2Te): δ -1079.3 (J PbTe
) 4100 Hz).

724 Organometallics, Vol. 19, No. 5, 2000
Communications
do not form isolable phosphine tellurides, we are unable
to examine their reactivities toward the distannane.
However, an attempted experiment using phenyldieth-
ylphosphine telluride as an alternate revealed that its
apparent reactivity in a similar treatment was higher
than that of Et3PdTe, but lower than that of
t-Bu3PdTe. To gain more reliable information related
to the second step of the catalytic cycle, we examined
the reactivity of phosphine selenides, which are ther-
mally stable and nondissociative analogues of the tel-
lurides. Similar treatment with (Me3Sn)2 showed that
the reactivity decreased in the order Ph3PdSe >
t-Bu3PdSe > n-Bu3PdSe; the trend is the reverse of the
PdSe bond strength.15 If we consider a similar reactivity
trend in the catalytic reaction between distannanes and
tellurium (eq 1), we must accept that the foregoing
statement about the rate-determining step is not ap-
plicable to triarylphosphines. The relatively low cata-
lytic activity of the triarylphosphines may not be
associated with the reactivity of the phosphine telluride
toward the distannane, but simply because of the
unfavorable equilibrium for the generation of the tri-
arylphosphine telluride.
Extensive study on the phosphine-catalyzed insertion
of chalcogen elements is now in progress.
Ack n ow led gm en t. We are grateful to the J apan
Science and Technology Corporation (J ST) for the
partial financial support through the CREST (Core
Research for Evolutional Science and Technology) pro-
gram and for a postdoctoral fellowship to F.M.
OM990728S
(14) Despite increasing number of reactions that use R′3PdTe as
tellurium transfer reagent, the experimental data relevant to the
transfer mechanism are sorely lacking. Although dependent on the
structure of R′, phosphine tellurides R′3PdTe are known to be in
equilibrium with Te and R′3P in solution (refs 4 and 5). However, a
recent study of the bond strength of n-Bu3PdTe (52 kcal mol-1) has
doubted the importance of the equilibrium in reactions: Capps, K. B.;
Wixmerten, B.; Bauer, A.; Hoff, C. D. Inorg. Chem. 1998, 37, 2861. It
is interesting in this context to note that the stoichiometric reaction
between Et3PdTe and (Me3Sn)2 was not affected by an addition of free
PEt3 (2-10 equiv).
(15) The PdSe bond dissociation energy of t-Bu3PdSe is not avail-
able. However, PdX (X ) O, Te) bonds in analogous t-Bu3PdX are
known to be exceptionally longer than the PdX bonds with linear alkyl
groups bound to the phosphorus. Therefore, the PdSe bond strength
is envisaged to be n-Bu3PdSe > t-Bu3PdSe. (a) Rankin, D. W. H.;
Robertson, H. E.; Seip, R.; Schmidbaur, H.; Blaschke, G. J . Chem. Soc.,
Dalton Trans. 1985, 827. (b) Kuhn, N.; Schumann, H.; Wolmersha¨user,
G. Z. Naturforsch. B 1987, 42, 674.
(16) Schumann, H.; Thom, K.-F.; Schmidt, M. J . Organomet. Chem.
1964, 2, 361.