R4*Tl3Cl and R6*Tl6Cl2 (R* =SitBu3) - The first compounds with larger clusters containing covalently linked thallium atoms

Article abstract of DOI:10.1002/1521-3773(20010401)40:7<1232::AID-ANIE1232>3.0.CO;2-F

The largest Tl clusters to date with covalently linked Tl atoms are contained in the title compounds obtained from TlCl₃ and two molar equivalents of NaSitBu₃ in THF at -78°C. The structure of (SitBu₃)₆Tl₆Cl₂, which contains two Tl₃Cl four-membered rings linked through the central Tl atoms and the Cl atoms, is depicted.

Full text of DOI:10.1002/1521-3773(20010401)40:7<1232::AID-ANIE1232>3.0.CO;2-F

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truncation gap of 53 mm). The radius of the cone was 20 mm, and the angle
between the cone and plate was 28. The experiments were performed at
358C for the single-headed surfactant 1 and at 258C for CTAB, 2, and 3.
Both the steady shear (flow-step) and oscillatory shear (stress control)
measurements were performed and the measurements were taken over a
frequency sweep range of 0.001 to 100 s 1. The rheometer has a built-in
computer which converts the torque measurements into either G' (the
storage modulus) and G'' (the loss modulus) in oscillatory shear experi-
ments or viscosity in flow-step measurements.
*
*
R4 Tl3Cl and R6 Tl6Cl2 (R* ˆ SitBu3)ÐThe First
Compounds with Larger Clusters Containing
Covalently Linked Thallium Atoms**
Nils Wiberg,* Thomas Blank, Hans-Wolfram Lerner,
Dieter Fenske und Gerald Linti
Dedicated to Professor Hansgeorg Schnöckel
on the occasion of his 60th birthday
Received: August 16, 2000
Revised: January 2, 2001 [Z15649]
Many compounds of the compositions TlR3 and TlR (R ˆ
inorganic, organic group) exist with thallium in the oxidation
states ‡iii and ‡i,[1] (the Tl R bonds in the former
compounds are more covalent in nature, those in the latter
more electrovalent), whereas very few compounds of the
composition TlR2 with thallium in the oxidation state ‡ii are
known to date. They form dimers R2Tl TlR2 with a covalent
Tl Tl bond (Tl Tl 2.914 (R ˆ Si(SiMe3)3),[2] 2.966 (R ˆ
SitBu3),[3] 2.881 Š (R ˆ SitBu2Ph )[4]). A few TlI compounds
also have Tl Tl bonds; however, as weak interactions with
Tl Tl distances >3.3 Š these vary significantly from the
strong interactions in the three reported dithallanes with
Tl Tl distances <3.0 Š (e.g. (PhCH2)5C5Tl ´´´ TlC5(CH2Ph)5:
Tl Tl 3.632 Š;[5] [(Me3Si)3CTl]4: Tl Tl 3.322 and 3.627 Š;[6]
{MeSi[N(Tl)tBu]3}2 has a Tl Tl distance in the intermediate
range (3.146 Š) and in addition several very weak Tl Tl
interactions;[7] in {MeC[CH2N(Tl)SiMe3]3}2 and other TlI
amides Tl Tl interactions exclusively occur with very large
Tl Tl distances (>3.6 Š)[8]). Thallium cluster compounds
containing more than two covalently linked thallium atoms
were hitherto unknown.
[1] F. M. Menger, J. S. Keiper, Angew. Chem. 2000, 122, 1980 ± 1996;
Angew. Chem. Int. Ed. 2000, 39, 1906 ± 1920.
[2] J. M. Schnur, Science 1993, 262, 1669 ± 1676.
[3] a) R. Zana, Y. Talmon, Nature 1993, 362, 228 ± 230; b) S. Bhattachar-
ya, S. De, Chem. Eur. J. 1999, 5, 2335 ± 2347.
[4] R. Oda, I. Huc, M. Schmutz, S. J. Candau, F. C. Mackintosh, Nature
1999, 399, 566 ± 569.
[5] K. Kalyanasundaram, J. K. Thomas, J. Am. Chem. Soc. 1977, 99, 2039 ±
2044.
[6] a) S. De, V. K. Aswal, P. S. Goyal, S. Bhattacharya, J. Phys. Chem.
1996, 100, 11664 ± 11671; b) M. Dreja, W. P. Hintzen, H. Mays, B.
Tieke, Langmuir 1999, 15, 391 ± 399; c) J. S. Higgins, H. C. Benoit,
Polymers and Neutron Scattering, Clarendon Press, Oxford, 1994;
d) V. Receveur, D. Durand, M. Desmadril, P. Calmettes, FEBS Lett.
1998, 426, 57 ± 61; e) G. Kostorz in Neutron Scattering, Vol. 15 (Ed.: G.
Kostorz), Academic Press, New York, 1979, pp. 227 ± 289; f) J.
Trewhella, S. C. Gallagher, J. K. Kruegu, J. Zhao, Sci. Prog. Oxford
1998, 81, 101 ± 122.
[7] J. B. Hayter, J. Penfold, Colloid Polym. Sci. 1983, 261, 1022 ± 1030.
[8] S. H. Chen, T. L. Lin in Methods of Experimental Physics, Vol. 23B
(Eds.: D. L. Price, S. K. Skold), Academic Press, New York, 1987,
pp. 489 ± 542.
[9] J. H. Fendler, Membrane Mimetic Chemistry, Wiley, New York, 1982.
[10] S. Bhattacharya, S. Haldar, Langmuir 1995, 11, 4748 ± 4757.
[11] V. K. Aswal, P. S. Goyal, Phys. Rev. E 2000, 61, 2947 ± 2953.
[12] a) T. Shikata, H. Hirata, T. Kotaka, Langmuir 1987, 3, 1081 ± 1086;
b) M. Löbl, H. Thurn, H. Hoffmann, Ber. Bunsen-Ges. Phys. Chem.
1984, 88, 1102 ± 1106; c) H. Rehage, H. Hoffmann, J. Phys. Chem.
1988, 92, 4712 ± 4719; d) H. Rehage, H. Hoffmann, Mol. Phys. 1991,
74, 933 ± 973; e) T. M. Clausen, P. K. Vinson, J. R. Minter, H. T. Davis,
Y. Talmon, W. G. Miller, J. Phys. Chem. 1992, 96, 474 ± 484; f) V. K.
Aswal, P. S. Goyal, P. Thiyagarajan, J. Phys. Chem. B 1998, 102, 2469 ±
2473.
We obtained compounds of this type, namely the trithallane
*
*
R4 Tl3Cl (1) and the hexathallane R6 Tl6Cl2 (2), in the attempt
to synthesize sterically overloaded disupersilylthallium chlo-
*
ride R2 TlCl (R* ˆ supersilyl ˆ SitBu3) analogously to the
[9]
*
preparation of R2 ECl (E ˆ Al, Ga, In) from the trihalide
ECl3 and two molar equivalents of supersilylsodium NaR* in
tetrahydrofuran (THF). Treatment of TlCl3 in THF at 788C
with NaR* in the molar ratio 1:2 leads to the slow (several
hours) formation of a red-brown reaction solution as well as a
[*] Prof. Dr. N. Wiberg, Dr. T. Blank
Department Chemie der Universität
Butenandtstrasse 5 ± 13 (Haus D), 81377 München (Germany)
Fax : (‡49)89-2180-7865
E-mail: niw@cup.uni-muenchen.de
Dr. H.-W. Lerner
Institut für Anorganische Chemie der Universität
Marie-Curie-Strasse 11, 60439 Frankfurt am Main (Germany)
Prof. Dr. D. Fenske[‡]
Institut für Anorganische Chemie der Universität
Engesserstrasse, Geb. 30.45, 76128 Karlsruhe (Germany)
Prof. Dr. G. Linti[‡]
Anorganisch-chemisches Institut der Universität
INF 270, 69120 Heidelberg (Germany)
‡
[ ] Crystal structure analyses
[**] Compounds of Silicon, Part 143. Supersilyl Compounds of Boron and
Its Homologues, Part 12. This work was supported by the Deutsche
Forschungsgemeinschaft and by the Fonds der Chemischen Industrie.
Part 42: N. Wiberg, W. Niedermayer, J. Organomet. Chem. 2001, in
press; Part 11. M. Kehrwald, W. Köstler, A. Rodig, G. Linti, T. Blank,
N. Wiberg, Organometallics 2001, in press.
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molecules formed directly in this way or indirectly after the
supersilanation of TlCl oligomerize or insert into the
*
Tl Cl bonds of R*TlCl2 and R2 TlCl five and two times,
respectively.
Studies on the reaction of TlCl3 with varying amounts NaR*
as well as on the thermolysis of the intermediate products
formed hereby support these hypotheses for the formation of
1 and 2. Thus, the reaction of TlCl3 with the equimolar amount
of NaR* in THF at 788C indeed leads to a solution of light
yellow dichlorosupersilylthallane R*TlCl2.[11] With two molar
equivalents of NaR* in THF at low temperatures it is not
black-brown precipitate. From the THF solution at 258C or
from a toluene solution obtained from extraction of the
precipitate with toluene ( 788C) and likewise kept at 258C,
the compounds 1 and 2, respectively (at least 1 forms in the
THF solution very slowly at 258C), crystallized in the course
of several months. The nature of fraction of the precipitate
which remained after extraction with toluene has still to be
clarified (oligomeric TlR*?).
*
chlorodisupersilylthallane R2 TlCl that is formed butÐas
describedÐthe trithallane 1 and the hexathallane 2 (rapid
heating of a solution of TlCl3/2NaR* cooled to 788C in THF
to room temperature leads exclusively to R*Cl and a black
*
precipitate). The yellow thallane R2 TlCl was obtained finally
*
*
after many failed attempts (e.g. TlCl3 ‡ NaR*, MgR2 , ZnR2 ;
The red trithallane 1 and the black hexathallane 2 probably
form according to the Equations (1) and (2). Both Tl cluster
*
Tl2R4 ‡ HCl, Ph3CCl) by addition of Me3SiCl to a solution of
TlCl3 and three molar equivalents of NaR* in THF at 788C;
Me3SiR* was formed as a by-product.[12] On heating the
corresponding solution without adding Me3SiCl, dark green
THF; 78 o C; 20 h; then 25 o
C
3TlCl ‡ 6NaR*
6TlCl ‡ 11NaR*
1 ‡ 2R*Cl
2 ‡ 5R*Cl
(1)
(2)
!
!
6 NaCl
*
tetrasupersilyldithallane Tl2R4 is formed, which is also
accessible from TlBr and NaR*.[3] Possibly, in the present
THF; 78 o C; 20 h; then 25 o
C
case a compound is formed initially that contains disupersi-
11 NaCl
‡
*
lylthallonium R2 Tl (counterion R*NaCl ?; see Scheme 1).
The cations could react with Cl donors such as Me3SiCl to
compounds are air-, moisture-, and light-sensitive and ther-
molyze in C6D6 at room temperature slowly and very slowly,
respectively, leading to the formation of R*Cl (dissolved in
C6D6) and a black precipitate (oligomeric TlR*?), which at
1008C in the presence of C6D6 slowly transforms into
elemental thallium and deuterated supersilane R*D (supersi-
lyl radicals probably form initially, which dimerize quickly and
reversibly and stabilize slowly and irreversibly on addition of
hydrogen: 2R* >(R*)2; R* ‡ C6D6 !R*D ‡ C6D5 ).[10]
The mechanism of the reactions of TlCl3 and NaR* leading
to 1 and 2 is still not completely clear. Possibly, the
supersilanation of TlCl3 initially leads to the compounds
*
give R2 TlCl, whereas in the absence of Me3SiCl they would
*
be slowly reduced by excessive NaR* to give Tl2R4
‡
*
(Scheme 1). The dark yellow cation R2 Tl also forms from
[13]
*
R2 TlCl on addition of AlCl3 in CD2Cl2.
Whereas the thermal decomposition of the thallane
R*TlCl2 dissolved in THF into TlR* and TlCl (Scheme 1)
*
already occurs at 508C, the thallane R2 TlCl decomposes
very slowly (over a period of many days) in C6D6 even at room
temperature via 1 to give R*Cl and the above-mentioned
black precipitate (oligomeric TlR*?), which at higher temper-
aturesÐas already mentionedÐis transformed into Tl and
R*D. Thus, TlR*, which is formed slowly thermolytically from
.
.
.
*
R*TlCl2 and R2 TlCl (Scheme 1), which through R*Cl elimi-
*
*
R2 TlCl, could in statu nascendi react with R2 TlCl to give
trithallane 1, which, in turn, would decompose even slower
with the release of supersilylthallium, which has a tendency to
nation decompose into TlCl and TlR*, respectively. The TlR*
*
oligomerize. Since R2 TlCl does not occur in the solutions of
TlCl3/2NaR* in THF, which at low temperatures lead to 1 and
2, another compound (which still has to be identified;
R*ClTl TlClR*?) derived from R*TlCl2 and NaR* must be
responsible for the formation of 1 and 2.
Figures 1 and 2 show the structures of the molecules 1 and 2
in the crystal.[14] The central structural element of the
trithallane 1 is a planar Tl3Cl four-membered ring (sum of
*
angles 359.918) with a R*Tl-R2 Tl-R*Tl chain (Tl Tl 2.92 Š
*
(av)). The Si2Tl plane of the R2 Tl unit is almost perpendicular
(898) to the Tl3Cl plane. The hexathallane 2 contains two Tl3Cl
four-membered rings with R*Tl-R*Tl-R*Tl chains (Tl Tl
2.93 Š (av)), which are linked with each other through the
central Tl atoms (Tl Tl 2.85 Š). As a result of additional
Tl Cl bonds between the Tl3Cl four-membered rings, these
are, in contrast to those in 1, no longer planar (sum of angles
344.38 (av); dihedral angle Tl-Tl-Cl-Tl in the rings 135.88
(av)).
Scheme 1. The reaction of TlCl3 with NaR*. [a] This reaction proceeds via
an unidentified compound.
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with toluene (30 mL; 788C). Black crystals of 2 (0.500 g, 0.200 mmol;
21%) precpitated from the extract at 258C over the course of six months.
1: 1H NMR (C6D6, TMS, internal): d ˆ 1.395 (br.; 2SitBu3), 1.410 (br.;
2SitBu3); 13C{1H} NMR (C6D6, TMS, internal): d ˆ 23.10 (6CMe3), 23.70
(6CMe3), 33.70 (6CMe3), 33.89 (6CMe3); 29Si{1H} NMR (C6D6, TMS,
external): d ˆ 99.1 (d; 1J(Si,203,205Tl) ˆ 1431, 1436 Hz; 2SitBu3), 100.2 (d;
1J(Si,203,205Tl) ˆ 1450, 1455 Hz; 2SitBu3). 2: 1H NMR ([D8]toluene, TMS,
internal): d ˆ 1.371 (d; 4J(H,Tl) ˆ 1.33 Hz; 4SitBu3), 1.393 (br.; 2SitBu3);
13C and 29Si NMR in [D8]toluene: not observed. Note: In a repeat of the
reaction, NMR spectra (1H, 13C, 29Si) of the filtrate cooled to 258C were
recorded immediately after heating to room temperature and thereafter at
certain intervals (replace THF for C6D6). They show that at 258C the
trithallane 1 is formed only slowly (in the course of weeks) from an
unidentified precursor (R*ClTl TlClR*?) (1H NMR (C6D6, TMS, inter-
nal): d ˆ 1.36 (d; 4J(H,Tl) ˆ 3.74 Hz); 29Si{1H} NMR (C6D6, TMS, external):
d ˆ 97.1 (d; 1J(Si,203,205Tl) ˆ 1447, 1441 Hz). According to the NMR spectra
the solution contained only traces of hexathallane 2.
Figure 1. Molecular structure of 1 in the crystal (SCHAKAL plot; atoms
with arbitrary radii; the hydrogen atoms are omitted for clarity). Selected
bond lengths [Š] and angles [8]: Tl1-Tl2 2.9093(7), Tl1-Tl3 2.9262(8), Tl2-
Cl1 2.808(3), Tl3-Cl1 2.803(3), Tl1-Si1 2.641(3), Tl1-Si2 2.645(3), Tl2-Si3
2.678(3), Tl3-Si4 2.696(3), Si-C 1.944 (av); Si1-Tl1-Si2 143.9(1), Si1-Tl1-Tl2
105.55(7), Si2-Tl1-Tl2 101.04(6), Si1-Tl1-Tl3 103.51(9), Si2-Tl1-Tl3
102.32(7), Tl2-Tl1-Tl3 85.85(3), Si3-Tl2-Cl1 101.24(11), Si3-Tl2-Tl1
166.70(9), Cl1-Tl2-Tl1 92.06(7), Si4-Tl3-Cl1 101.60(10), Si4-Tl3-Tl1
166.58(7), Cl1-Tl3-Tl1 91.82(7), C5-Si1-C9 111.5(10), C-Si-C 110.9 (av),
C-Si-Tl 107.6 (av).
Received: October 10, 2000 [Z15934]
[1] N. Wiberg, Lehrbuch der Anorganischen Chemie, 101st ed, de Gruyt-
er, Berlin, 1995; Chemistry of Aluminum, Gallium, Indium and
Thallium (Ed.: A. J. Downs), Chapman and Hall, London, 1993.
[2] S. Henkel, K. W. Klinkhammer, W. Schwarz, Angew. Chem. 1994, 106,
721; Angew. Chem. Int. Ed. Engl. 1994, 33, 68.
[3] N. Wiberg, K. Amelunxen, H. Nöth, M. Schmidt, H. Schwenk, Angew.
Chem. 1996, 108, 110; Angew. Chem. Int. Ed. Engl. 1996, 35, 65.
[4] N. Wiberg, T. Blank, D. Fenske, unpublished results .
[5] H. Schumann, C. Janiak, J. Pickardt, U. Bömer, Angew. Chem. 1987,
99, 788; Angew. Chem. Int. Ed. Engl. 1987, 26, 789; see also M. A.
Paver, C. A. Russell, D. S. Weight in Comprehensive Organometallic
Chemistry, Vol. 2 (Eds.: E. W. Abel, F. G. A. Stone, G. Wilkinson),
Pergamon, Oxford, 1995, p. 528.
[6] W. Uhl, S. O. Keimling, K. W. Klinkhammer, W. Schwarz, Angew.
Chem. 1997, 109, 64; Angew. Chem. Int. Ed. Engl. 1997, 36, 64.
[7] M. Veith, A. Spaniol, J. Pöhlmann, F. Gross, V. Huch, Chem. Ber. 1993,
126, 2625.
[8] C. H. Galka, L. H. Gade, Inorg. Chem. 1999, 38, 1039, and references
therein; K. W. Klinkhammer, S. Henkel, J. Organomet. Chem. 1994,
480, 167, and references therein.
[9] N. Wiberg, K. Amelunxen, H.-W. Lerner, H. Nöth, J. Knizek, I.
Krossing, Z. Naturforsch. B 1998, 53, 333.
[10] N. Wiberg, Coord. Chem. Rev. 1997, 163, 217.
[11] The existence of the thallane R*TlCl2 at low temperatures (29Si{1H}
NMR (THF, 508C): d ˆ 62.2 (d, 1J(Si,203,205Tl) ˆ 513.6, 516.7 Hz;
SitBu3) is supported not only by the smooth thermolytic decomposi-
tion into R*Cl and TlCl, but also by the reaction with LiPh, which
affords diphenylsupersilylthallane R*TlPh2. 1H NMR (C6D6, TMS,
internal): d ˆ 1.120 (br.; SitBu3), 7.18, 7.43 (each m; o-, p-, m-H of
2Ph); 13C{1H} NMR (C6D6, TMS, internal): d ˆ 28.45, 32.77 (3CMe3,
3CMe3), 127.41, 127.50, 129.00, 141.70 (m-, p-, o-, i-C of 2Ph); 29Si
NMR: not observed.
Figure 2. Molecular structure of 2 in the crystal (SCHAKAL plot; atoms
with arbitrary radii; the hydrogen atoms are omitted for clarity). Selected
*
bond lengths [Š] and angles [8] of one of the two almost identical R3 Tl3Cl
units and its linkage with the other unit: Tl1-Tl2 2.854(2), Tl1-Tl5 2.908(2),
Tl1-Tl4 2.944(2), Tl4-Cl2 2.918(6), Tl4-Cl1 2.984(7), Tl5-Cl1 2.866(7), Tl1-
Si5 2.630(7), Tl4-Si1 2.715(6), Tl5-Si4 2.680(8), Si-C 1.951 (av); Si5-Tl1-Tl2
137.1(2), Si5-Tl1-Tl5 112.4(2), Tl2-Tl1-Tl5 94.83(5), Si5-Tl1-Tl4 113.8(2),
Tl2-Tl1-Tl4 100.89(5), Tl5-Tl1-Tl4 84.11(4), Si1-Tl4-Cl2 99.7(2), Si1-Tl4-
Tl1 159.6(2), Cl2-Tl4-Tl1 99.1(1), Si1-Tl4-Cl1 105.3(2), Cl2-Tl4-Cl1 82.0(2),
Tl1-Tl4-Cl1 85.4(1), Si4-Tl5-Cl1 99.2(2), Si4-Tl5-Tl1 172.5(2), Cl1-Tl5-Tl1
88.3(1), Tl5-Cl1-Tl3 103.6(2), Tl5-Cl1-Tl4 84.1(2), Tl3-Cl1-Tl4 91.9(2),
C-Si-C 111.7 (av), C-Si-Tl 107.3 (av).
[12] According to X-ray structure analysis (in collaboration with H. Nöth,
*
M. Warchhold), the air-, water-, and light-sensitive thallane R2 TlCl,
which is obtained from pentane at 238C in the form of yellow plates,
has
a
planar Si2TlCl framework and thus containsÐunlike
‡
Me2TlCl[1]Ðno linear [RTlR] ions (possibly the very different sizes
‡
*
of the ions R2 Tl and Cl prevent the formation of an energy-poor
ionic crystal). 1H NMR (C6D6, TMS, internal): d ˆ 1.319 (br.;
2SitBu3); 13C{1H} NMR (C6D6, TMS, internal): d ˆ 28.35, 32.75 (each
3
v br.; 6CMe3, 6CMe3; the former signal is a doublet with J(C,Tl) ˆ
55 Hz); 29Si NMR: not observed; MS: m/z (%): 603 (67) [M
Cl],
‡
Experimental Section
‡
‡
‡
581 (22) [M
C4H9], 405 (90) [M
SitBu3], 205 (100) [Tl ] (each
NaR* (0.513 g, 11.3 mmol) in THF (25 mL) was added dropwise to a
solution of TlCl3 (1.74 g, 5.60 mmol) in THF (50 mL) at 788C. The
initially orange solution (NaR*) was transformed slowly at 788C into a
dark red-brown suspension. After a reaction time of 20 h the mixture was
filtered at 788C to separate the insoluble components. Compound 1
(0.350 g, 0.240 mmol; 13%) precipitated as red crystals from the filtrate,
which had been concentrated to about 30 mL and kept at 258C, over the
course of six months. The separated dark brown precipitate was extracted
correct isotopic pattern).
‡
*
[13] Disupersilylthallonium tetrachloroaluminate [R2 Tl] [AlCl4] , which
had hitherto not been obtained as crystals suitable for an X-ray
structural analysis: 1H NMR (CD2Cl2, TMS, internal): d ˆ 1.40 (br.;
2SitBu3); 13C{1H} NMR (CD2Cl2, TMS, internal): d ˆ 27.39, 33.25
(each v br.; 6CMe3, 6CMe3); 29Si NMR: not observed; 27Al NMR
(CD2Cl2, Al(NO3)3 in D2O, external): d ˆ 101.14 (AlCl4 ; full width at
half maximum 140 Hz).
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[14] Crystal structure analyses: 1: monoclinic, space group C2/c, a ˆ
2511.8(5), b ˆ 1309.2(3), c ˆ 4291.8(9) pm, b ˆ 101.37(3)8, Vˆ
13.84(1) nm3, Z ˆ 4; 1calcd ˆ 1.473 Mgm 3, m ˆ 7.109 mm 1, F(000) ˆ
6040. Data collection: 2q ˆ 3.86 ± 48.148, 18 ꢀ h ꢀ 28, 13 ꢀ k ꢀ 13,
49 ꢀ l ꢀ 49, 24666 reflections, of which 9010 were independent
(Rint ˆ 0.0781) and 611 refined. All non-hydrogen atoms were refined
anisotropically and the H atoms were included in calculated positions,
R1 ˆ 0.0663, wR2 ˆ 0.1794 (F > 4s(F)), GOF(F 2) ˆ 1.083; max. resid-
rearrangement of diphenylphosphinites that are readily
available from the corresponding unsaturated 1,2-diols
(Scheme 1). Herein we report the use of this rearrangement
for a practical preparation of new chiral 1,2-diphosphanes and
their application in highly efficient rhodium-catalyzed asym-
metric hydroborations.
3
Å
ual electron density 2.556 eŠ . 2: triclinic, space group P1, a ˆ
1548.9(3), b ˆ 1738.7(4), c ˆ 2097.4(4) pm, a ˆ 78.37(3), b ˆ 68.79(3),
OPPh2
3
g ˆ 77.12(3)8, Vˆ 5.0877(18) nm3, Z ˆ 2; 1calcd ˆ 1.473 Mgm
,
m ˆ
1
OPPh2
OPPh2
OH
OH
9.621 mm
,
F(000) ˆ 2396. Data collection: 2q ˆ 4.22 ± 51.848,
a)
b)
18 ꢀ h ꢀ 18, 21 ꢀ k ꢀ 21, 25 ꢀ l ꢀ 25, 55309 reflections, of which
18432 were independent (Rint ˆ 0.0939) and 829 refined. All non-
hydrogen atoms were refined anisotropically and the H atoms were
included in calculated positions, R1 ˆ 0.1313, wR2 ˆ 0.4136 (F >
4s(F)), GOF(F 2) ˆ 1.851; max. residual electron density
17.506 eŠ 3. The crystals of 2 are extremely thin, very small platelets,
and therefore the data set was strongly influenced by absorption
effects. An absorption correction could not be performed. Several
maxima of similar size occur which are all located at the periphery of
the molecule (60 ± 150 pm from the H atoms). If only data up to 2q ˆ
448 are considered for the refinement of the structure, the structural
parameters are altered only slightly: R1 ˆ 0.128; max. residual electron
density 13.40 Š 3. The intensities were measured with a STOE-IPDS
PPh2
O
5a
4
P(O)Ph2
P(O)Ph2
6a: 85 % from 4
Scheme 1. Tandem [2,3] sigmatropic rearrangement of diphenylphosphin-
ite. a) ClPPh2, 4-DMAP, Et2O, RT; b) toluene, reflux, 42 h.
diffractometer with
a
CCD area detector (MoKa radiation, l ˆ
0.71073 Š). The crystals were mounted in perfluoropolyether oil;
Tˆ 183(2) and 193(2) K, respectively. The structures were solved by
using direct methods and refined against F 2 for all observed
reflections. (Structure solution with SHELXS 94, refinement using
SHELXL 93). Crystallographic data (excluding structure factors) for
the structures reported in this paper have been deposited with the
Cambridge Crystallographic Data Centre as supplementary publica-
tion nos. CCDC-150538 (1) and CCDC-150539 (2). Copies of the data
can be obtained free of charge on application to CCDC, 12 Union
Road, Cambridge CB21EZ, UK (fax: (‡44)1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk). .
The racemic mixture of the diacetate 1 is prepared in three
steps in about 40% overall yield starting from 1,3-cyclo-
hexadiene.[3] This diacetate is easily resolved using Pseudo-
monas fluorescens lipase[4] to afford the chiral diacetate (S,S)-
2 (43% yield, 99.5% ee) and a mixture of monoacetates
(R,R)-3 (45% yield, 94% ee; Scheme 2). The two enantio-
OAc
OAc
(S,S)-2: 43 %, 99.5 % ee
OAc
d)
a)–c)
OH
OAc
OAc
+
rac-1: 40 %
OAc
OH
New C2-Symmetrical 1,2-Diphosphanes for the
Efficient Rhodium-Catalyzed Asymmetric
Hydroboration of Styrene Derivatives**
(R,R)-3a
(R,R)-3b
45 %, 94 % ee
Â
Stephane Demay, Florence Volant, and Paul Knochel*
OH
OAc
(R,R)-3a
OAc
OH
OH
OH
e)
Chiral 1,2-diphosphanes are important ligands for asym-
metric metal catalysis.[1] Their synthesis is challenging espe-
cially if the stereoselective formation of secondary carbon ±
phosphorus bonds is desired. Recently, we have developed a
method[2] that provides a stereoselective synthesis of cyclic
1,2-diphosphane oxides using a tandem [2,3] sigmatropic
+
(R,R)-3b
(R,R)-4: 29 % from 1, 99.5 % ee
Scheme 2. Preparation of the optically pure diol (R,R)-4. a) Br2 (1 equiv),
CHCl3, 58C; b) 1m KOH, H2O, RT, 96 h; c) Ac2O (2 equiv), pyridine, RT,
12 h; d) Pseudomonas fluorescens lipase, pH 7, buffer, 388C; e) NaOMe
(1 equiv), MeOH, RT, 1 h; f) recrystallization from AcOEt.
[*] Prof. Dr. P. Knochel, Dipl.-Ing. S. Demay, Dipl.-Chem. F. Volant
Department Chemie, Ludwig-Maximilians-Universität
Butenandstrasse 5 ± 13, Haus F, 81377 Munich (Germany)
Fax : (‡49)89-2180-7680
meric diols (R,R)-4 and (S,S)-4 are obtained in optically pure
forms after saponification and recrystallization from AcOEt
in yields of 29 and 31%, respectively (from 1). These
compounds have been prepared on a multigram scale and
are a convenient starting material for a range of new chiral
phosphanes of interest for metal catalysis.
The reaction of (R,R)-4 with several diarylchlorophos-
phanes[5] provides the corresponding diphosphinites 5a ± c
which undergo a smooth [2,3] sigmatropic rearrangement in
E-mail: paul.knochel@cup.uni-muenchen.de
[**] We thank the Deutsche Forschungsgemeinschaft (Leibniz program),
The Institut de Recherches Servier (Suresnes, France), and PPG-
SIPSY for financial support. We thank also BASF AG (Ludwigsha-
fen), Chemetall GmbH (Frankfurt), and Degussa ± Hüls AG (Hanau)
for the generous gift of chemicals.
Supporting information for this article is available on the WWW under
http://www.angewandte.com or from the author.
Angew. Chem. Int. Ed. 2001, 40, No. 7
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