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Inversely Coordinating Silanide Ions in an Oligomeric Sodium Alcoholate.

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[5] J.-D. van Loon, D. Kraft, M. J. K . Ankone, W. Verboom, S. Harkema, W. Vogt.
V. Bohmer, D. N. Reinhoudt, J. Org. Chem. 1990.55, 5176-5179.
[6] A . M . McKervey, M. Owens, H.-R. Schulten, W. Vogt, V. Bohmer, Angew.
Chem. 1990, 102, 326-328; Angew. Chem. I n f . Ed. Engl. 1990, 29, 280-282.
[7] D. Kraft, J:D. van Loon, M. Owens, W. Verboom, W. Vogt, M. A. McKervey,
V. Bohmer, D. N. Reinhoudt, Tetrahedron Lett. 1990, 31, 4941 -4944.
[8] Z. Asfari, R. Abidi, F. Arnaud, J. Vicens, J. Inclusion Phenom. Mol. Recognit.
Chem. 1992, 13, 163-169.
[9] Z. Asfari, J. Weiss, J. Vicens, Pol. J. Chem. 1992, 66, 709-711.
[lo] J. L. Atwood, S. G. Bott, C. Jones, C. L. Raston, J. Chem. Soc. Chem. Commun. 1992, 1349-1351.
[ l l ] X. Delaigue, M. W. Hosseini, A. De Cian, J. Fischer, E. Leize, S. Kieffer, A.
Van Dorsselaer, Tetrahedron Lerf. 1993, 34. 3285-3288.
I121 S. Arimori, T. Nagasaki, S. Shinkai. J. Chem. SOC.Perkin Trans. 1 1993, 887889.
[I31 V. Bohmer, H . Goldmann, W. Vogt, J. Vicens, Z. Asfari, TefrahedronLeu. 1989,
30, 1391-1394.
[14] A. Arduini. G. Manfredi, A. Pochini, A. R. Sicuri, R. Ungaro, J. Chem. Sor.
Chem. Commun. 1991, 936-937.
[IS] Z . Asfari, J. Vicens. J. Weiss, Tetrahedron Lett. 1993, 34. 627-628.
[I61 E. Kelderman, L. Derhaeg, G. J. T. Heesink, W. Verboom, J. F. J. Engbersen,
N. F. van Hulst, A. Persoons, D. N. Reinhoudt, Angew. Chem. 1992, 104.
1107-1110; Ange". Chem. Int. Ed. Engl. 1992, 31, 1075-1077.
[17] H. Goldmann. W. Vogt, E. Paulus, V. Bohmer, J. A m . Chem. Sor. 1988, 110.
6811 -6817.
[IS] V. Bohmer, H. Goldmann. W. Vogt. E. F. Paulus, F. L. Tobiason, M. J. Thielman, J. Chem. SOC.Perkin Trans. 2, 1990. 1769-1775.
Treatment of monosilane with dispersed sodium in diethyleneglycol dimethyl ether (diglyme) leads at 100 "C to sodium silanides of composition NaSi(SiH,),H,-, (n = 0-3).['1 After about 20 days a few reproducible, colorless crystals separate
as by-product from the filtered yellowish solution of the
silanides. The X-ray structure
showed that it was the
sodium-oxygen cage compound [Na,(O,C,H, 1)6(SiH3)2](2,
Fig. I).[''' Apparently the methyl-oxygen bond of the solvent
diglyme is cleaved by the alkali metal sodium to a small extent
under these drastic conditions.["]
Inversely Coordinating Silanide Ions in an
Oligomeric Sodium Alcoholate""
Fig. 1. Crystal structure of the neutral complex 2 [14]. Selected distances [A] and
angles ["I: Na-Na 3.013-3.055(2), Na-O,,,,,,,,,, 2.300-2.427(3), Na-O,,,., 2.3892.457(2), Na4-Sil 3.048(2), Si-H 1.38-1.42(3), N a 4 - H 2.52-2.67(3); H-Si-H
96.0, 97.1. 91.3(18).
Hans Pritzkow, Thomas Lobreyer, Wolfgang
Sundermeyer,* Nicolaas J. R. van Eikema Hommes,
and Paul von Rague Schleyer
In 1961 Ring and Ritter succeeded in characterizing the molecule KSiH, .['I Their results were confirmed by Weiss et aLf2Iin
1970 and extended by structural analyses on the alkali metal
silanides MSiH, (M = Rb, Cs). All three compounds crystallize
in the NaCl structure, and according to NMR spectroscopic
studies the SiH, groups rotate freely at their lattice sites down
to a temperature of - 100 "C. Becker et al.13]were able to detect
an orthorhombic low-temperature modification of KSiH, for
the first time in 1989 (/I-KSiH,).
In contrast, according to ab initio calculations[41the molecule
LiSiH, should have a remarkable structure with inverted C,,
geometry, which is favored over the conventional tetrahedral
van't Hoff structure by 10 kJmol-'. Thus the silyl anion H,Siis expected to bind to the lithium cation through the negatively
polarized hydrogen atoms and not in the usual way. The calculated structures of the analogous NaSiH, isomers ( l a , b; see
Fig. 2) are very close in
but the van't Hoff structure
is the more stable by about 4-8 kJmol-'. Experimental proof
of these theoretically predicted molecular structures did not
exist previously. We now report the X-ray crystal structure of an
oligomeric sodium alcoholate to which two H,Si- anions are
coordinated with inverted C,, symmetry, as well as the ab initio
calculation of a simplified model of this compound.
[*I Prof. Dr. W. Snndermeyer, Dr. H. Pritzkow, DipLChem. T. Lobreyer
Anorganisch-chemisches lnstitut der Universitit
lm Neuenheimer Feld 270, D-69120 Heidelberg (FRG)
Telefax: lnt. code (6221)564197
Dr. N. J. R. van Eikemd Hommes, Prof. P. von R. Schleyer
Institut fur Organische Chemie 1 der Universitit Erlangen-Numberg
Henkestrasse 42, D-91054 Erlangen (FRG)
[**I This work was supported by the Bundesministerinm fur Forschung und Technologie (project no. 0328980 A) and the Fonds der Chemischen lndustrie. We
thank Degussa. Messer-Griesheim, and BASF for making chemicals available.
Q VCH Verlagsgesellsrhaf~mbH, 0.69451 Weinheim. 1994
The eight sodium atoms form a cube, the faces of which are
capped by alcoholate oxygen atoms of the six monomethyl diethyleneglycolate ions, which are each bonded to four sodium
atoms [Na-0 2.300-2.417 A]. Together these fourteen atoms
form an approximate rhombododecahedron. The two ether
oxygen atoms of each monomethyl diethyleneglycolate ion are
bound to a common sodium atom ( N a - 0 2.389-2.457 A).
Thus six of the eight sodium atoms are fivefold coordinated to
oxygen atoms. The coordination of the other two sodium atoms
is completed by a SiH; ion. The silyl hydrogen atoms were
localized in a difference Fourier synthesis, and their positions
subsequently refined; they are situated on the side facing the
sodium atom. The determined Na-Si distance [3.048 A] is clearly longer than the distance calculated by us for the isolated
NaSiH, molecule l a (2.71 A); the Si-H distances (1.381.42 A) are shorter (calculated: 1.56 A). The SiH, unit forms a
steep pyramid in which the H-Si-H angles vary between 91 and
96" (calculated for 1 a : 92"). The Na-Si-H angles in the crystal
[57.7-62.0(13)"] are slightly larger than the calculated angles
(56 "). Besides the bonds to the hydrogen atoms and the interaction with the sodium atom, the silicon atom has no other contacts to neighboring atoms closer than 3.2 A.
Although according to calculations[5s61 the van't Hoff isomer
1 b of the monomeric, gaseous NaSiH, is more stable than the
inverted isomer l a , for 2 the inverted structure is apparently
energetically favored. To determine whether this is a contradiction of theory or whether 1a,b are not suitable models for 2,
calculations were performed on a [ (NaOH),NaSiH,] complex
as model (that is, on a species which reflected half of the crystallographically studied sodium-oxygen cage 2). The MP2/631G* geometries of the inverted structure 3a and the van't Hoff
structure 3b are depicted in Figure 2 and contrasted with the
structures of the isomeric molecules l a and l b . The Na-Si
distance in 3 is longer than in the corresponding isomers of 1,
0570-0833194j0202-0216 $ 10.0Oi ,2510
Angew. Chem. I n f . Ed. Engl. 1994, 33, No. 2
1 3 5 0 ~ .1296w, 1245 w, 1200m, 1082vs, 937vs, 849% 768 w; MS (70eV,
gly = OC,H,OC,H,OCH,):
mlz (%): 875 (Na,(gly),), 734 (Na,(gly),), 591
(Na,(gly),), 449 (Na,(gly),, loo%), 307 (Na,(gly),), 165 (Na,(gly)), 121, 89, 59.
Received: August 14, 1993
Revised version: October 15, 1993 [Z6285IE]
German version: Angew. Chem. 1994, 106, 221
Fig. 2. Structures of 1a and its van't Hoff isomer 1b calculated with ab initio
methods (MP2/6-3lG*) and of the [Na(OH),NaSiH,] complexes 38 and 3b.
Whereas l a is 6.5 kJmol-' less stable than l b , 3 a is 6 kJmol-' more stable than
3b (data from MP4sdq/6-31* calculations).
but is still shorter than in solid 2. Such deviations in the molecular geometry in the gas phase and in the solid state can be
explained by dielectric effects in the crystal field.[12]The elongation of the bond in this case is certainly attributable to the higher
coordination of the alkali metal atom in 2. However, most important for the comparison between 3 a and 3 b are the relative
energies, which show that in 3 the complexation reverses the
order for stability from that found for 1. On the highest level
used for the calculations (MP4sdq/6-31G*//MP2/6-31G*), the
inverted complex 3 a is 6 kJmol-' more stable than 3b. The
results of the calculations are thus in accord with the experimentally determined data.
For gaseous lithium silanide the inverted structure is, according to calculations,[41more favorable than the van? Hoff structure on account of the contributions of the agostic Li-H interactions. In contrast, for gaseous sodium silanide the corresponding Na-H interactions are weaker; with the result that the
contribution of the metal -silicon bond energy that favors the
van? Hoff structure increases in importance. The inversion of
stabilities in the isomeric complexes 3 a and 3b is a consequence
of the additional electrostatic interaction (H*- . . . Na6+)of the
SiH, group with the three sodium atoms of the (NaOH), fragment. The preferred conformation of the SiH, groups in 2 is
therefore attributable to these interactions.
Experimental Procedure
Sodium (10 g, 0.44 mol) was dispersed in diglyme (500 mL) at 100°C in a reactor
fitted with a hollow stirrer and baMe plate and converted into sodium silanides of
the composition NaSi(SiH,).H,-, (n = 0-3) by treatment with continuously added
monosilane [7]. After 4 h the monosilane addition was stopped, and the contents of
the reactor allowed to cool to room temperature under nitrogen. The resulting
yellow solution was filtered over a G-4 frit. After about 20 days colorless crystals
precipitated from the solution of sodium silanides. The solution was removed by
syringe, and the crystals were selected manually.
2: 'H NMR (90 MHz, [Dl,]1,2-dimethoxyethane,
TMS): 6 = 3.47 (m, 12H), 3.61
(m, 30H). 3.80 (m. 18H); "Si NMR (17.75 MHz, diglyme, C,D,): S = - 83.7; IR
(KBr): B[cm- '1 = 2878 vs, 2657 m, 2010 w, 1937 w, 1674 w, 1608 s, 1456 s, 1373 w,
Angen,. Chem. Int. Ed. Engl. 1994. 33, No. 2
[l] M. A. Ring, D. M. Ritter, J. Phys. Chem. 1961, 65, 182.
[2] E. Weiss, G . Hencken, H. Kiihr, Chem. Eer. 1970, 103, 2868-2872.
[3] 0. Mundt, G. Becker, H.-M. Hartmann, W. Schwarz, Z . Anorg. Allg. Chem.
1989, 572, 75-88.
[4] P. von R. Schleyer, T. Clark, J. Chem. SOC.Chem. Commun. 1986,1371- 1373.
(51 B. T. Luke, J. A. Pople, M.-B. Krogh-Jespersen, Y. Apeloig, J. Chandrasekhar,
P. von R. Schleyer, J. Am. Chem. SOC.1986, 108,260-269.
[6] A. S. Zyubin, T. S. Zyubina, 0 . P. Charkin, P. von R. Schleyer, Russ. J. Inorg.
Chem. 1990.35, 1044.
[7] T. Lobreyer, J. Oeler, W. Sundermeyer, H. Oberhammer, Chem. Ber. 1993,126,
665-668; see also [S].
[S] T. Lobreyer, H. Oberhammer, W. Sundermeyer, Angew. Chem. 1993,105,587588; Angew. Chem. Ini. Ed. Engl. 1993, 32, 586-587.
M = 960.98, space group P2,/n, a =12.905(6),
[9] 2 (C,,H,,Na,O,,Si,):
b = 12.025(6), c = 16.739(9)A, p = 94.80(3)", V = 2588.5 A3, Z = 2, four-circle diffractometer (Mo,, radiation, w scan, T = - 100 "C), 4140 independent
reflections (of which 3137 with 1>20,). Refinement against F Z with all reflections, non-hydrogen atoms anisotropic, hydrogen atoms in calculated positions (CH,) or in rigid groups (CH,) with variable C-H distances, common
isotropic temperature factors for identical groups, H atoms on Si relined isotropically in found positions. R , = 0.035, wR, = 0.095 (for all reflections), 312
parameters. Residual electron density: besides a maximum of 0.4 e k 3 in the
vicinity of the Si atom, between -0.17 and + 0.18 eA-,. All calculations were
performed with the program SHELXL93 [13]. Further details of the crystal
structure investigation may be obtained from the Fachinformationszentrum
Karlsruhe, D-76344 Eggenstein-Leopoldshafen (FRG) on quoting the depository number CSD-400477, and the journal citation.
[lo] T. Lobreyer, W. Sundermeyer, H. Oherhammer, lecture at the Xth Int. Symp.
Organosilicon Chem., Poznan, Poland, August 1993.
[ l l ] A. Maercker, Angew. Chem. 1987,99,1002-1019, Angew. Chem. Int. Ed. Engl.
1987, 26, 972-989.
[12] M. Biihl, P. von R. Schleyer. Angew. Chem. 1991,103,1179; Angew. Chem. Int.
Ed. Engl. 1991, 30, 1160.
(131 G. M. Sheldrick, SHELXL93, Universitat Gottingen, 1993.
[14] E. Keller, SCHAKAL88, Universitat Freihurg, 1988.
Syntheses of Cyclopentanols by a
Silicon-Induced Cascade Reaction **
Michael-Ralph Fischer, Andreas Kirschning, Tycho
Michel, and Ernst Schaumann *
The synthesis of chiral cyclopentane derivatives is a component of many natural product syntheses."] The diverse synthetic
possibilities include the chemistry of the trimethylenemethane
equivalent,''. ring expansion reactions of three-I4]and four-I5]
membered rings as well as radical cyclization reactions.[61Extending our work on the synthesis of cyclopropanes with the
homo-Peterson reactionL6]we have now developed a simple
route to cyclopentanes including optically active examples. In
this route the lithium derivatives la-c, which are easily obtained from silylated thioacetals,[6] react with the epoxy paratoluenesulfonate 2 to afford the silyl ethers 5a-c (Scheme 1,
Table 1). Apparently the carbanion of 1 attacks the unsubstituted carbon atom of the epoxide in 2 chemoselectively and regioselectively to give 3.Finally, a 1,4-carbon to oxygen shift of
[*I Prof. Dr. E. Schaumann, M.-R. Fischer, Dr. A. Kirschning,
DipLChem. T. Michel
Institute fur Organische Chemie der Universitat
Leibnizstrasse 6, D-38678 Clausthal-Zellerfeld (FRG)
Telefax: Int. code + (5323)72-2858
[**I This work was supported by the Fonds der Chemischen Industrie
Verlagsgesellschaft mbH, 0-69451 Weinheim. 1994
0570-0833~94/0202-0217$10.00+ ,2510
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coordination, sodium, oligomer, alcoholate, silanide, inversely, ions
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