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X-ray Structure of [Ru(bpy)3]0 An Expanded Atom or a New Electride.

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[I] M. R. Wasielcwski. Chem. Rev. 1992, 92, 435.
[2] J. P. Collman. F. C Anson, C. E. Barnes, S. C. Bencosme, T. Geier, E. R. Evitt,
R. P. Kreh. K Meier, R. B. Pettman, J. Am Chem. Soc. 1983,105,2694: C. K.
Chang. I . Ahdalmuhdi. Angesr. Chem. 1984, 96, 154; Angew. Chem Inr. Ed.
Engl 1984, 23. 164: H Me1er.Y. Kobuke, S. Kugimiya, J Chem. Soc. Chem.
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51.2838; D. Heiler, G. McLendon, P. Rogalskyj, J A m . Chem. Soc 1987, 109,
604: A. Osuka. K . Maruyama, ibid. 1988,110,4454; A. M. Brun, A. Harrunan,
V. Hcitii. J. P Savauge, ibid. 1991, 113, 8657; H. A. Staab. T. Carell, Angeir.
Chem. 1994, 106. 1534: Angew. Chem. Int. Ed. Engl. 1994, 33, 1466; M. J.
Crossley, P. L. Burn, J Chem. Soc. Chem. Commun. 1991,1569; H. Segawa, K
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[3] a ) V. S.-Y Lin. M. Therien. Chew. Eur. J 1995, 1, 645; b) V. S:Y. Lin. S. G.
DiMagno. M. Therien, Science 1994, 264, 1105.
[4] D. P Arnold. G A. Heath. J. Am. Chem. Soc. 1993, 115, 12197; H. L. Anderson. S. J. Marun. D. D C. Bradley, Angeiv. Chem. 1994, 106. 711; AngeM
Cliiwi. / n t . E d Engl. 1994, 33, 655.
[ 5 ] S. Prathapm. T E Johnson. J. S. Lindsey. J Am. Chem. Soc 1993, 115, 7519;
R W. Wagner. J. S. Lindsey. hid. 1994, 1f6,9759.
[h] a) H . Higuchi. K Shimidzu, J. Ojima, K.Suglura, Y. Sakata. Tetruhedron Lerr.
1995. 36, 5359. h) M. 0. Senge, K. R. Gerzevske, M.G H. Vicente, T. P.
Forsyth, K . M. Smith, Angew. Chem. 1993, 105, 745; Angen. Chem. h i . Ed.
Engl 1993. 3-7. 750: F. Wurthner. M. S Vollmer, F. Effenberger, P. Emele,
I>. U Meyer. t3. Port. H. C. Wolf, J. Am. Chem. Soc. 1995, 117>8090.
[7] R. W Wagner. T E. Johnson, F. Li. J. S. Lindsey, J Org. CIiem. 1995,60,5266.
[8] Judging from the 500 MHz ' H NMR spectra of the reaction mixture, products
coupled at the other positions were not present (less than 1 "A)
[9] Treatment of 1 with I, resulted in no reaction after 72 h. I,/Ag' salt is effective
in abstracting an electron from 1: A. G. Padilla. S.-M. Wu, H. J. Shine, J Chem.
So(.. Chein. ('onzniun. 1976. 236: J. E Baldwin, M. J. Crossley, J. DeBernadis,
Tefroh~rlron1982. 38, 685.
1101 After the rexrion of I with I equiv I, and AgPF, for 5 min. the product
distribution is 1 (17%). 2 (11 %), and 3 (4%)
1111 G. Barnett. K. M. Smith, J. Chem. Soc. Cliem. Commun. 1974, 772; K. M.
Smith. G H. Barnett. B. Evans, 2. Martynenko. J Am. Chem S ~ F1979,101,
[I 21 The one-electron oxidation potentials of 1 and 2 in CH,CI, are 0.34 and 0.33 V,
respectively (vh. ferrocenelferrocenium ion).
[I 31 The similar dimers and trimers were obtained from other metalloporphyrins
such as Mg"-porphyrin and Pd"-porphyrin, and free-base porphyrin by treatment with AgI o r IJAg salt, the relative reactivities depend on the one-electron
oxidation potentials.
[I41 R. H. Felton in The Porphyt-ins, Vol. 5(Ed.: D . Dolphin), Academic Press, New
York, 1978, p. 53.
[15] J:H. Fuhrhop. D. Mauzerall.1 Am. Chem. Soc. 1969, 91,4174; J. Fajer, D. C.
Borg, A. Forman, D Dolphin, R. H. Felton, ibid. 1970, 92, 3451; J. H.
Fuhrhop. P. Wasser. D. Riesner, D. Mauzerall, D. ibid 1972, 94, 7996.
[16] H. Song, C. A. Reed, W. R. Scheidt, J A m . Chem. Soc. 1989, I l l , 6867; H.
Song. R. D. Orosz, C A. Reed, W. R. Scheidt, W. R. h o g . Chem. 1990, 29,
[I71 J:H. Fuhrhop. E. Baumgartner, H. Bauer, J Am. Chem. Soc. 1981,103, 5854.
I181 A. L Balch. B. C Noll. S. M. Reid, E. P. Zovinka. J Am. Chem. So<. 1993,
[I91 J. H. Fuhrhop in The Porph,vrin.s. Ed. 2 (Ed.: D. Dolphin), Academic Press,
New York. 1978, p. 131.
[20l Even stericallq demanding meso-iodination was possible with zinc(]]) 5,15diphenylporphyrin. R. W Boyle, C. K. Johnson, D. Dolphin, J. Chem. Soc.
Clirm. Comnnm. 1995, 527. We also found a similar effective iodination reaction using an Ag' salt and I; A. Osuka, H. Shimidzu, unpublished results.
[21] According to thc exciton coupling theory, the following equation predicts the
splitting energy. AE. versus the number of chromophores, N: A E = 2 E,cos[n/
( N I)]: M. Kasha. Radiar. Res. 1963, 20, 55.
(221 T. Nagata. A. Osuka. K. Maruyama, J Am. Chem. Sor. 1990, 112, 3054; A.
Osuka. N. Tanahr. S Nakajima, K Maruyama, J Chem. Soc. Perkin Trans. 2
1996. 199
[I31 P. G Seyhold. M. Goutermann. J Mol. Specrrosc. 1969, 31, 1.
[ N l N. Nakashinia. M . Murakawa. N. Mataga, Bull Chem. Soc Jpn. 1976,49,854
X-ray Structure of [R~(bpy)~]O
An Expanded Atom or a New Electride?**
Eduardo E. Perez-Cordero, Charles Campana, and
Luis Echegoyen*
Dedicated to Professor Waldemar Adam
on the occasion of his 601h birthday
We recently prepared and chemically characterized single
crystals of electroneutral [M(bpy),l0 complexes (where bpy is
2,2'-bipyridine and M is Fe, Ru, and Os).[" These materials had
been previously reported as powders.['] Herein we present the
X-ray crystal structure characterization of the [Ru(bpy)J0 complex; the transport and magnetic properties of this material have
been previously discussed.[31
The compound [Ru(bpy)J0 (1) is conceptually similar to the
first crystalline cryptatium (2), which was described in 1991.I4]
For the latter neutral, "expanded-atom" type species 2, formed
by reductive electrocrystallization of sodium tris(bipyridine)
cryptate, the crystal structure analysis provides d e a r evidence
that the unpaired electron density is mainly localized on only
one of the bpy subunits.[41This observation is consistent with
MO calculations for bpy, which show that the LUMO (2,2'bond) is bonding and thus that its occupation by an added
electron would tend to flatten the bpy s u b ~ n i t . ' ~Both
compounds may be compared, at least conceptually. to endohedral
fullerenes, since in all three cases there are central metal cations
surrounded by organic ligands that effectively delocalize the
negative charge to afford overall electroneutral species.[61
[Ru(bpy),](PF,), and IRu(bpy),](PF,), were recently structurally characterized.[7a1The latter was the first report of the
structure of the Ru3+ complex, while the structure of the R u 2 +
complex had been described before (see citation in reference
[ 6 ] ) .The results presented here for 1 are mainly compared to
those for [R~(bpy),]*+.['~]
[*] Prof. L. Echegoyen, E. E. Perez-Corder0
Department of Chemistry, University of Miami
Coral Gables, FL 33124 (USA)
Fax: Int code +(305)284-4571
e-mail lechegoyen(a
Angeic. Clwin In1 Ed Eng/. 1997, 36, A">.112
Dr. C. Campana
Siemens Industrial Automation, Inc.
6300 Enterprise Lane. Madison, WI 53719 (USA)
The authors thank the National Science Foundation (DMR-9119986 and
CHE-9313018) and the Donors ofthe Petroleum Research Fund (PRF-27827ACl) for generous support. We gratefully acknowledge Prof H. B. Burgi (Lahoratorium fur Kristallographie. Universitat Bern) for the help offered during
the reviewing stages of this work.
Veriagsgesell.~chufim b H , 0.69451 Wemherm, 1997
0570-0R33/97;3601-0137$ 15.00+
[Ru(bpy),]' occur in the R u - N an< C(5)-C(6) distances:
Ru-N bond lengths of 2.053-2.056 A and C(5)-C(6) bond
lengths of 1.476- 1.482 8, have been reported for the unreduced
complex,[71while the ranges of bond lengths observed here for
the reduced complex are 2.041 -2.059 8, and 1.431 - 1.448 A,
respectively. The shortening of the C(5)-C(6) bond could indicate some electron localization on the bpy ligands.l4, 'I
In contrast to these small molecular structural differences,
analysis of the molecular packing reveals profound differences
with respect to the crystalline structure of the parent complex
[Ru(bpy),](PF,),. Figure 2a shows the arrangement of the Ru
atoms in the crystal structure of 1. Six molecules form a hexag-
As described previously,['] crystals of 1 were grown on a Pt
cathode from a ImM solution of the R u 2 + complex in acetonitrile containing 0.1 M tetrabutylammonium hexafluorophosphate. The process was conducted under strict exclusion of
air (lo-' Torr) after the solution had been frozen in liquid nitrogen. The electrocrystallization was done using a two-electrode
configuration at constant current (1 1 pAcm-2). After shiny
needles had grown, dry Ar gas was allowed to enter, and the
crystals were removed from the solution and stored under
A stereoview of the structure of two [Ru(bpy),]' units along
the C , axis, together with the numbering scheme is shown in
Figure 1 .[81 There are two crystallographically independent
Figure 1. Stereoview of two [Ru(bpy),]" units in crystals of 1 (program SHELYTL
X P [9]). Dotted lines highlight potential CH x interactions. Although distances are
reasonable for these interactions, the relative orientations are not optimal; see text
for more details.
[Ru(bpy)JOunits in the lattice, Ru(A) and Ru(B) (see Figure 3);
however, intrinsic differences between these are relatively small.
Selected bond lengths and angles are summarized in Table 1. [ l o ]
Table 1. Selected bond lengths [A] and angles
for 1 [a]
Site A
Site B
Ru N(1)
Ru N(2j
N(1) -C(5j
N(2) C(6)
C(5) C(6)
2.042 (2)
[a] Numbers in parentheses are cstimated standard deviations in the least significant digits.
The three bpy ligands are equivalent and almost perfectly planar: dihedral angles between pyridine rings are 2.8 and 6.7" for
ligands in crystallographic sites A and B, respectively. The
molecular structure exhibits only minor deviations from ideal
octahedral coordination geometry. Thus, the main conclusion
derived from the intrinsic structure of each [Ru(bpy),]' unit is
that they closely resemble that of the precursor [ R ~ ( b p y ) , ] ' + . [ ~ ~
Interestingly, if all of the distances are taken into consideration,
the structure of [Ru(bpy),l0 more closely resembles that of the
complex cation [Ru(bpy),]'+. Thus, we can coiiclude from these
structural similarities that the structures are not particularly
sensitive to the total electronic density. Small but perhaps significant differences between the structures of [Ru(bpy),12 and
Figure 2. a ) Stereoview of the positions of 15 Ru centers in the lattice of 1. providing a representation of the packing structure. "Pseudo hexagonal" planes are evident, as well as the central stack, which is offset by c / 2 relative to the units in the
hexagonal arrangements. In this representation there is a twofold elongation along
the c axis, bat not along the other axes. in order to accentuate the structural features
described in the text. b) Stcreovicw ofthe van der Waals surfaccs o f a group of seven
[Ru(bpyj,]" units from a pseudo hexagon and the central stack. Intermolecular x-x
contacts are clearly evident along the hexagonal system, however. these are not very
extensive nor optimal, see text for more details.
onal "pseudo plane" perpendicular to the C, axis; the molecules
are slightly displaced above and below this plane (by 0.216 A).
The distances between the six Ru centers are 9.572 A. Above
and below this plane there are similar "pseudo hexagons". Because of c glide planes, the chirality alternates as one moves
along the C, axis. This is consistent with the results of the X-ray
structure analysis of [Ru$bpy),I2 +.I7] However, in the latter the
Ru-Ru distances (8.1 1 A) along this axis are longer than those
in 1 (7.722 8,).[7a1
Down the middle of these hexagonal structures there are
stacks of [Ru(bpy)JO units, which again exhibit alternating
chirality. These stacks are offset by 3.861 A relative to the
hexagonal average planes (Figure 2a). The closest Ru- Ru distances between these stacks and the pseudo hexagon are 10.233
and 10.395 A.
In [Ru(bpy),](PF,), two PF; ions per complex occupy interstitial positions.[61These anions do not inhibit intermolecular
interactions between complex isomers along C,, but they do
prevent short intermolecular contacts between the complex molecules in the u, h plane.17]The opposite situation is true for the
electrocrystallized material 1. Figure 2b shows a stereoview of
the van der Waals surface of one of the hexagonal units. The
interplanar distance observed between bpy units in adjacent
complexes around the hexagon is 3.26 A; that is, optimal for 7c-7~
stacking. Owing to the 3 axis, the three units that sit slightly
above the hexagonal plane have the same chirality, but opposite
to that of the three units that sit slightly below the plane. In the
unreduced complex, the pseudo layers perpendicular to the C,
axis are composed of units with uniform chirality.
The dotted lines in Figure 1 connect the centers of the vicinal
pyridine rings in two consecutively stacked [Ru(bpy),l0 units.
These stacks, which are composed of alternating enantiomeric
molecules, show a reasonable complementary fit if CH-7c interactions are invoked; the centroid-to-centroid distances oscillate
between 5.128 and 5.368 A,["*
The most important issue that needs to be addressed after
presenting the detailed analysis of the structure and packing of
1 concerns the location of the additional electron density.
[Ru(bpy),l0 contains two more electrons than the starting material [Ru(bpy),12+, yet no significant distortion of the intrinsic
geometry around the central Ru atom occurs. Based on all previous electrochemical observations of [Ru(bpy),]'+ as well as
on its electronic properties, localization of the electron density
on the ligands was expected.[', 5 , 1 2 ) However, if the additional
electron density is mainly localized on bpy-like orbitals, a distorted [Ru(bpy),lo structure would be expected, in which two of
the ligands should show different properties than the third ligand. Such a situation was observed for ~ r y p t a t i u m .A
~ ~similar
distortion was observed for a reduced, binaphthyridineruthenium complex, [Ru(binaphthyridine),](PF,),
Reduction with
one electron leads to a crystalline material, [Ru(binaphthyridine),](PF,), the geometry of which is very distorted relative to that of the unreduced complex. Thus, these two cases
exhibit considerable distortions upon reduction; however, this is
not the case for [Ru(bpy),]O.
There are three ways to explain why 1 behaves differently
from cryptatium and [Ru(binaphthyridine),](PF,). One is to
assume that the two additional electrons are delocalized in an
orbital that contains equal contributions from the three ligands.
If this is true, the material fits well the description of an "expanded atom" in which a symmetrically reduced ligand environment surrounds the central metal ion.
Another possible interpretation is that if the electrons are localized on two ligands, a disordered structure in which the unreduced ligand is randomly distributed over the three positions
would average the observed coordinates. The disorder would
result in only small increases of the anisotropic displacement
parameters ( A 2 / 4 < 0.001 A) since A values (the difference between bond lengths in bpy and (bpy)- taken from reference [4])
are small. A third possible explanation is that the electrons
occupy. at least partially, some lattice sites. In this case the
crystalline material could be formally described, at least partially, as an ele~tride.''~.
Analysis of the crystal packing of [Ru(bpy>,lo (1) reveals the
presence of two cavities per Ru atom, in which, like in electrides,
there could be electron density.['4. 151 The positions of the InterAngew. Chem In1 Ed. Engl. 1997, 36, No. 112
Figure 3. Projection of the lattice structure of 1 along the C , axis; the hydrogen
atoms are omitted for clarity. The central stack is surrounded by six intermolecular
spaces, which correspond approximately to the positions of the PF; ions in the
[Ru(bpy),](PFb),structure. These spaces contain cavities in which lattice electrons
could probably be locahzed, at least partially.
molecular spaces, which are essentially empty cavities in the
lattice structure, can be easily appreciated from Figure 3. They
approximately correspond to the positions where the PF; ions
are found in the structure of [Ru(bpy),](PF,), .[71 These cavities
are connected by channels that seem to run in a somewhat
twisted fashion along the C, axis.
Based on the available data it is impossible at the present time
to ascertain unequivocally which of these interpretations is correct. It is possible that 1 has some of the extra electron density
delocalized between the bpy ligands and the lattice cavities, and
that the delocalization over the complex molecules is nearly
perfectly symmetric. This and many other questions about the
nature and properties of this material are currently under investigation.
Received: February 6, 1996
Revised version: October 10. 1996 [Z8791 IE]
German version: Angew Chcm. 1997, 109, 85-88
Keywords: electrocrystallization
ands ruthenium
electronic structure
N lig-
[I] E. Perez-Cordero, R. Buigas, N. Brady, L. Echegoyen, C. Arana, J -M. Lehn,
Helv. Chim. Aciu 1994, 77, 1222.
[2] a) D. E. Morris, K. W. Hanck, M. K. DeArmond, lnorg Chem. 1985,24,977;
h) J. Am. Chem. Soc. 1983, 105, 3032; c) A. G . Motten. K W Hanck, M. K.
DeArmond. Chem. Phys. Letr. 1981, 79, 541
[3] M. J. Wagner, J. L. Dye, E. Perez-Cordero, R. Buigas. L. Echegoyen, J. Am.
Chem. Sac. 1995, 117, 1318.
[4] L. Echegoyen, A. DeCian, J. Fischer, J.-M. Lehn, Angen. Chem. 1991,103,884.
Angew. Chem. Ini. Ed. Engl. 1991, 30, 838.
[5] Y Ohsawa, M -H Whangbo, K. W Hanck. M. K. DeArrnond, inorg. Client.
1984, 23, 3426.
I61 T Suzuki, Y Maruyama, T. Kato, T. Akasaka, K . Kobayashi, S. Nagase, K.
Yamamoto, H. Funasaka, T. Takahashi, J. Am. Chem. Soc 1995, 117, 9606.
[7] a) M Biner. H.-8. Bdrgi, A. Ludi, C. Rohr. J Am. Chem Soc. 1992,114,5197;
b) H. Tamura. N. Ikeda, T. Iguro, T. Ohno, G.-E. Matsubayashi, Acta Crystallogr. Sect. C 1996, 52, 1394.
[Sl X-ray structure determination of 1: A dark blue hexagonal needlelike crystal
ofapproximate dimensions 0.10 x 0.10 x 0.30 mm was coated with Paratone-N
oil under an argon atmosphere and immediately placed in a cold nitrogen
stream at 153 K on the X-ray diffractometer. The X-ray intensity data were
collected o n a standard Siemens SMART CCD area detector system equipped
e VCH Verlugsgesellschafi mhH, 0-69451 Wemherm, I997
0570-0833~971360/-01393 /5.00+ 2 5 9
with a normal focus molybdenum-target X-ray tube operated at 2.0 kW (50 kV.
40 mA) 191. A total of 1321 frames ofdata were collected using a narrow-frame
method with scan widths of 0.3' in w and exposure times of 30 sec per frame
using a crystal-to-detector distance of 6.015 cm (maximum 211 angle 51.62").
The total data collection time was approximately 13 h. Frames were integrated
with the Siemens SAINT program to yield a total of 14059 reflections, of which
= 0.0307, Laue symmetry hlmmm, R,,, = 0.01 79)
2213 were independent (R,,,
and 1993 were above 4u(F). The unit cell parameters (at 153 K) of
u = h = 16.5617(2), c = 15.4433(2)A were based upon least-squares refinement of the three-dimensional centroids of 8192 reflections. The cell volume
and density were 3668 A' and 1.547 gcm-3, respectwely. By assuming a merohedrally twinned trigonal specimen, twinning law (0 - 1 0 - 1 0 0 0 0 - 1 ) and
space group P%l, Ru of position A is found at (1/3,2/3. z ) (site simmetry C35)
and Ru of position Bat (O,O, 1/4) (site symmetry D332)with a twin population
of 0.501(3). The refinement of coordinates and anisotropic displacement
parameters converged a t R, = 0.0250, GOOF =1.144 (w =l/(uz(Fz)
(0.0090P)2 3.0338P), where P = (Fi +2F:)/3) for 1993 observations and
181 parameters (hydrogen atoms in calcukated positions, d(C-H) = 0.95 A).
Siemens Industrial Automation, Inc. 6300 Enterprise Lane. Madison, WI
53719 (USA)
Crystallographic data (excluding structure factors) for the structure reported in
this paper have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC-179-136. Copies of the data
can be obtained free of charge on application to The Director, CCDC, 12
Union Road, Cambridge CB2 IEZ, UK (fax: Int. code +(1223) 336-033; email:
a) W. L. Jorgensen, D. L. Severance, J Am Chem. Soc. 1990, 112.4768; b) S .
Paliwal, S. Geib, C. S. Wilcox, ibid. 1994, /16, 4497; c) K Miyamura, A.
Mihara, T. Fujii, Y Gohshi, Y Ishii, ibid. 1995, 1/7, 2377; d ) H. Adams, F. J.
Carver, C. A. Hunter, J. C. Morales, E.M. Seward, Angew. Chem. 1996, 108.
1628; Angew. Chem. Int. Ed. Engl. 1996,35, 1542.
Y. Ohsawa, M K. DeArmond, K W. Hanck. D. E.Morris. J. Am. Chem. Soc.
1983, 10.5, 6522
E. Perez-Cordero, N. Brady, L. Echegoyen, R. Thummel, C.-Y Hung, S. G.
Bott, Chem. Eur. J. 1996, 2, 781
a) J. L. Dye, Chemtrncts-hog. Chem. 1993,5,243; b) M J. Wagner, J. L. Dye,
Annu. Rev. Muter. Sci. 1993, 23. 223.
1. L. Dye, M. J. Wagner, G. Overney, R. H. Huang, T. F. Nagy, D. TomPnek,
1. Am. Chem. Soc. 1996, 1/8,7329.
Fluorinated oxiranes are suitable candidates for such investigations because of the small and rigid ring structure and their
strong infrared absorptions in the range of the CO, laser. Some
work on the influence of substituents on the ring structure of
highly fluorinated oxiranes has been
but up to
now monofluoroxirane has neither been prepared nor otherwise
experimentally investigated. Two publications describe theoretical computations of the molecular structure of the monofluorooxirane.['. lo] The anticipated shortening of the C - 0 bond at
the fluorinated carbon atoms relative to the C - 0 bond length
at the CH, carbon suggests the formation of a C - 0 double
bond at the CHF side of the ring upon elimination of hydrogen
fluoride. Both the structure and the proposed decomposition
pathway have to be verified by experiment. We have found
remarkably diverse phenomena in experiments with isotopic
labeling. Furthermore, fluorooxirane should also be important
in the chemical activation of fluoroethylene with oxygen atoms
('D oder 3P).[111In a general context, the calculation of the
circular dichroism of substituted oxiranes,r'21 the stereomutation at the carbon
and parity selection[141are of
Fluorooxirane 2 and 2,2-[2H,]-fluorooxirane 3 have been prepared according to Scheme 1, starting from chlorotrifluoroethylene. The preparation of the ester['51 and its reduction to
the optically active (-)-alcohol following the diastereoisomer
separation of chiorofluoroacetic acid have been
Synthesis, Structure, High-Resolution
Spectroscopy, and Laser Chemistry of
Fluorooxirane and 2,2-12H2]-Fluorooxirane**
Scheme 1
Hans Hollenstein, David Luckhaus, Jorg Pochert,
Martin Quack,* and Georg Seyfang
The last step is performed in analogy to the reaction of 2chloroethanol with potassium hydroxide to yield the unsubstituted oxirane already reported by W~rtz.~"]For the doubly
Dedicated to Professor Edgar Heilbronner
deuterated isotopomer the ester 1 is reduced with lithium aluon the occasion of his 75th birthday
minium deuteride. The isotopic purity of the CD, groups of the
alcohol and the oxirane has been checked by infrared and mass
Fundamental questions concerning symmetry, structure, and
to be at least 99%.
dynamics of chiral molecules beyond classical structural conFigure 1 shows the gas-phase infrared spectra of 2 and 3 in the
cepts"' may in future be answered by spectroscopy and laser
region important for C0,-laser excitation. For the normal mode
chemical investigations.[21For this purpose, small chiral moleassignment
of the fundamentals and to characterize the comcules that can be investigated by reaction dynamics and by gaspounds, the equilibrium geometry and the infrared spectra have
phase IR and UV spectroscopy with rotational resolution have
been calculated ab initio (Gaussian'94, MP2) with basis sets of
to be found. Only few examples of this type have been reported,
size up to triple-zeta with additional polarization
for instance CHBrClF[31or the substituted thiiran-l-o~ides.[~~
functions (C,F,O: 5s4p2d; H: 3 ~ 3 ~ ~ The
' ~ ' experimental
ab initio wavenumbers in Table 1 show differences of the order
[*I Prof. Dr. M . Quack, Dr. H. Hollenstein, Dr. D. Luckhaus,
of a few percent. The sequences of strong and weak absorptions
DiplLChem. J. Pochert, Dr. G . Seyfang
are identical for experiment and ab initio theory. The strongest
Laboratorium fur Physikalische Chemie
absorptions are due to the C-F chromophore at 1100 (3) and
ETH Zurich Zentrum
Universitatsstrasse 22, CH-8092 Zurich (Switzerland)
1125cm-' (2).
Fax: Int. code +(1)632-1021
The rotational structure of the vibrational bands has
e-mail: quack&
resolved in the spectra recorded on our BOMEM-DA002
[**I This work is supported by the Schweizerischer Nationalfonds zur Forderung
Fourier-transform infrared spectrometer with an instrumental
der wissenschaftlichen Forschung. We wish to thank T. K . Ha for assistance
with the ab initio calculations and U. Schmitt for help and discussions.
bandwidth of 0.004 cm-I (FWHM, apodized). In an iterative
0 VCH VerlngsgesellschujtmbH. 0-69451 Weinheim. 1997
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