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X-Ray Structure Investigation of 2 2-Diphenyl-1-(phenylsulfonyl)cyclopropyllithiumЦDimethoxyethane (23) A Sulfonyl УCarbanionФ Having an -C Atom with a Tetrahedral Configuration.

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[CpRhFe,(CO),(RC-CR)] has been reported by Vahrenkamp et al.;lX1 in that case, however, the formation of an
alkyne ligand by C-C bond formation did not occur.
The cleavage and formation of alkynes coordinated to a
cluster has been of great recent interest.[91
Received: February 25, 1988 [Z 2634 IE]
German version: Angew. Chem. 100 (1988) 871
CAS Registry numbers:
1, 94621-00-8; 2, 12129-77.0; 3, 114396-74-6
[ I ] W. J. Middleton, US Pat. 2831835 (1958); Chem. Abstr. 52 (1958)
14658 f; J. Heicklen, V. Knight, J. Phys. Chem. 69 (1965) 2484; L. Kevan,
P. Hamlet, J . Chem. Phys. 42 (1965) 2255; G . Bieri, J.-P. Stadelmann, F.
Thommen, J. Vogt, Helv. Chim. Acfa 61 (1978) 357; G . Bieri, A. Schmelzer, L. Asbrink, M. Jonsson, Chem. Phys. 49 (1980) 213.
[2] D. Lentz, I. Briidgam, H. Hartl, Angew. Chem. 97 (1985) 115; Angew.
Chem. Int. Ed. Engl. 24 (1985) 119.
131 Experimenfal Procedure: 1 (200 mg, 0.42 mmol) and 2 (150 mg, 0.6
mmol) in n-pentane (100 mL) were irradiated in a 100-mL photoreactor
(Philips HPK 125-W high-pressure mercury lamp, Pyrex glass) for
60 min. The reaction solution was then filtered through a ca. 5-cm-thick
layer of silica gel 60 (Woelm 63-200 pn). Unreacted 1 was eluted with
n-pentane. Elution with CH2Cl2 afforded 3. The solution was evaporated to dryness under vacuum. The residue was dissolved in n-pentane
and crystallized at -20°C. Yield: 118 mg (41%) of dark brown to black
crystals which decompose above 142°C; MS (80 eV): m / z 676 (M”),
([M-CO]’), 620 ([M-2COjS), 592 ([M-3CO1°), 564 ([M-4CO]”),
536 ([M-SCO]”),
508 ([M-6COIe),
490 ([M-7C0IQ),
( [ M - S C O ] ” ) , 424 ([M-9CO]”); high resolution of the molecular ion
peak calcd 675.8064, found 675.8048; IR (n-pentane): V = 2070.2 (vs),
2061.0 (s), 2040.6 (m), 2026.2 (vs), 2016.0 (vs), 2004.0 (w). 1999.2 (w),
1993.6 (w). 1983.6 (vw). 1967.6 (vw), 1959.0 (w). 1926.0 (vw), 1900.8 (vw)
cm-’; ‘9F-NMR(CD2C12,CFCI, ext. as standard): 6 = -22.1; ‘H-NMR
(CD2C12, G(CHDCI2)=5.35): 6= 1.80.
[4] K. Wade, Ado. Inorg. Chem. Radiochem. 18 (1976) I.
[ S ] Crystals of 3 suitable for crystal structure investigation were obtained
by recrystallization from n-pentane at - 20°C. Monoclinic, P2,/c,
a = 1642.7(5), b = 1938.8(4), c = 1558.1(6) pm, fl=99.61(3)’,
1.83 g c m - ’ ; R=0.078 (MoKo. k=71.07 pm, 10792 reflections,
8569 with 1>2o(l), anisotropic temperature factors, no H atom positions, 650 refined parameters, empirical absorption correction using the
DIFABS program of D. Stuarr and N . Walker [lo]). Further details of
the crystal structure investigation may be obtained from the Fachinformationszentrum Energie, Physik, Mathematik GmbH, D-7514 Eggenstein-Leopoldshafen 2 (FRG), on quoting the depository number CSD53047, the names of the authors, and the journal citation.
[61 R. Jackson, B. F. G. Johnson, J. Lewis, P. R. Raithby, S . W. Sankey, J .
Organomet. Chem. 193 (1980) C1; B. F. G. Johnson, J. W. Kelland, J.
Lewis, A. L. Mann, P. R. Raithby, J. Chem. Soc. Chem. Commun. 1980.
[7] B. F. G. Johnson, J. Lewis, K. T. Schorpp, J. Organomet. Chem. 91
(1975) C 13.
[8] H. Vahrenkamp, lecture at the 21th GdCh-Hauptversammlung, Berlin
191 A. D. Clauss, J. R. Shapley, C. N. Wilker, R. Hoffmann, Orgonomefallics
3 (1984) 619, and references cited therein; D. Nuel, F. Dahan, R. Mathieu, ibid. 4 (1985) 1436.
[lo] N. Walker, D. Stuart, Acta Crysfallogr.Secf. A39 (1983) 158.
X-Ray Structure Investigation of
2,2-Diphenyl-l-(phenylsuIfonyl)cyclopropyllithiumDimethoxyethane (213): A Sulfonyl “Carbanion”
Having an a-C Atom with a Tetrahedral
By Werner Hollstein. Klaus Harms, Michael Marsch, and
Gernof Boche*
Does the anionic C atom in a-sulfonyl “carbanions”
have to display a planar configuration or is a tetrahedral
[*] Prof. Dr. G. Boche, DiplLChem. W. Hollstein, Dr. K. Harms, M. Marsch
Fachbereich Chemie der Universitat
Hans-Meerwein-Strasse, D-3550 Marburg (FRG)
This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
0 VCH Verlagsgesellschafr mbH. 0-6940 Weinheirn. 1988
configuration also appropriate for stabilization by an
R S 0 2 group? The X-ray structure investigations of a-sulfonyl carbanions reported so far d o not provide a conclusive
answer to this question. In these examples, the environment of the a - C atom is either planar[’“] or does not deviate to a sufficiently large extent from planarity.[’b~‘~21
the “cyclopropyl effect”I3I is taken into consideration in
answering this question, one even arrives at contradictory
conclusions. Whereas Zimmerman et aI.I4]and Cram et al.I5J
found roughly the same equilibrium acidities for cyclopropyl- and isopropylsulfonyl compounds and DeBoer et a1.I6]
and Kirmse et a1.[’] reported higher kinetic acidities for cyclopropylsulfonyl compounds, Bordwell et aLLX1
higher acidities for the isopropyl compounds. Bordwell
concluded from his results that overlap of the carbon p
orbital with a sulfur d orbital was necessary for stabilization of the “anion”; accordingly, a-sulfonyl “carbanions”
should be planar like enolate and nitronate ions.18b1The
I3C-NMR investigations of Marquef et al.J9’ on the other
hand, revealed a hybridization of “between sp2 and sp3”
for the a - C atom of tBuS02CH2Li.Finally, detailed calculations performed by Streitwieser et aI.[”] on the stabilization of a negative charge by a n R S 0 2 group indicated that
a p,-d, interaction is not important. Thus, the energy difference (3-21C(*)+) between planar CH3S02CHy and a
CH3S02CH: structure in which the H atoms at C, are bent
from planarity by 20” is only t 0 . 5 7 kcal mol-’. The X-ray
crystal structure investigation of (l-phenylsulfonyl)-2,2-diphenylcyclopropyllithium 2, crystallized as 2,2-diphenyl-l(phenylsulfonyl)cyclopropyllithium-dimethoxyethane(2/3)
1 , which we describe here, supports those findings
indicating that a-sulfonyl “carbanions” are also stabilized
when the a-C atom has a tetrahedral configuration.‘”]
Compound l [ I 4 l is present as a dimer in the crystal (Fig.
1); the lithium atoms are bonded to the 0 atoms of the
sulfonyl groups and to two of the three dimethoxyethane
molecules. This results in the formation of the (S-O-Li0-S-0-Li-0) eight-membered ring characteristic of lithiosulfones.[’.21 The third molecule of dimethoxyethane cocrystallizes. Of special importance is the finding that the
PhS02 group is bent out of the plane of the cyclopropane
ring by 61.7(5)’ (S1 lies 131.5(3) pm above the plane of the
three-membered ring), so that the a-C atom deviates considerably from a planar configuration.”’] The C l - S l distance (167.6(7) pm) and the S1-01 distance (148.0(5) pm)
are 3.5 and 1.5 pm larger, respectively, than in [a-(phenylsulfonyl)ben~ylIithium(tmeda)]~.[’~~
A salient feature of lithiosulfones is also the additional coordination of the Li
atom to the a - C atom (CI-LiIA 244.0(14) pm); this is presumably due to the high charge density in the exocyclic
orbital containing the negative charge. The bond axis C1LilA is bent by 24.9(6)O out of the plane of the three-membered ring (LilA lies 103(1) pm below the plane of the
three-membered ring). Thus, pn-d, interaction indeed
plays no role in the stabilization of these (and other) a sulfonyl “carbanions.” Instead, an n-o* interaction is im-
0570-0833/88/0606-0846 $ 02.50/0
Angew. Chem Int. Ed. Engl. 27 (1988) No. 6
Received: January 28, 1988 [Z 2596 IE]
German version: Angew’. Chem. I00 (1988) 868
CAS Registry numbers:
1, 114491-70-2; 2, 114491-71-3
Fig. I . Crystal structure of 1 Ill]. Both the “dimer” and the cocrystallizing
molecule of dtmethoxyethane have a crystallographic center of symmetry.
Symmetry-generated atoms are marked with “A:’ Crystal structure data of 1 :
space group PT, 0=1014.7(3), b = 1069.3(2), c = 1191.9(3)pm, a=86.94(2),
8=88.69(2), y=85.89(2)’, Z = 2 (based on the monomer). Four-circle diffractometer CAD4 (Enraf-Nonius), Cu,, radiation, graphite monochromator,
4059 measured reflections in the range 8=2-50”, 180 K. Solution by direct
methods 1121, refinement 1131 to R=0.049 for 1923 unique reflections with
F > 3a(F), all non-hydrogen atoms anisotropic, H atoms, except for those on
the three-membered ring, “riding” with a common isotropic temperature factor. Important bond lengths [pm]: CI-C2 152.6(9); C2-C3 154.3(10); C b C 3
152.5(10); CI-SI 167.6(7); S I - 0 1 148.0(5); S1-02 147.1(4); CI-LiIA
244.0( 14): S K I 6 175.8(8). Further details of the crystal structure investigation may be obtained from the Fachinformationszentrum Energie, Physik,
Mafhematik GmbH, D-7514 Eggenstein-Leopoldshafen2 (FRG), on quoting
the depository number CSD-52892, the names of the authors, and the journal citation.
portant, as found by means of calculations.[”] Figure 2
shows the configuration at C1 and S1 as well as the conformation around C1-Sl.
Fig. 2 Configuration at C I and SI (not visible) as well as conformation
around CI-SI of 1. Important bond angles [“I: C2-Cl-SI 123.9(5); C3-CI-SI
120.5(5): 01-SI-02115.2(3); CIO-C2-C4 115.0(6); C2-Cl-C3 60.8(5); CI-C2C3 59.6(5): CI-C3-C2 59.7(5); torsion angles I”]: 01-SI-CI-CZ -72.0(6);
02-SI-CI-C3 90.8(6).
Compound 1 thus differs significantly from cyclopropyl
“anions,” whose negative charge is stabilized by delocalization, as in ester enolates or nitronates. Accordingly, enolate esters of cyclopropanecarboxylic acids are even highly
reactive at - 78°C owing to the additional strain caused by
the exocyclic double bond,[’61 and cyclopropylnitronate
can neither be trapped with an electrophile nor spectroscopically studied.“’] In contrast, 2,2-dimethyl-l-(phenylsulfonyl)cyclopropyllithium-fully
in accordance with the
above finding-is
even stable at 80°C in THF/
Angew. Chem. Int. Ed. Engl. 27 (1988) No. 6
[ I ] a) [(PhCHSO,Ph)Li(tmeda)],: G. Boche, M. Marsch, K. Harms, G. M.
Sheldrick, Angew. Chem. 97 (1985) 577: Angew. Chem. I n t . Ed. Engl. 24
(1985) 573; b) [(CH2S02Ph)Li(tmeda)]2:H.-J. Gais, H. J. Lindner, J .
Vollhardt, ibid. 97 (1985) 865 and 24 (1985) 859: c)
[(CH2=CHCHSO2Ph)Li(dig1yme)),: ibid. 98 (1986) 916 and 25 (1986)
939; the deviations from planarity are most striking in this case: the H
atom is bent out of the plane by 12”, the C atom by 14’ 1201.
[2] The structure of [(Me3SiCHSO2Ph)Li(tmeda)l2corresponds in essential
respects to the structure of the compounds mentioned in [la-c]: G.
Boche, W. Hollstein, M. Marsch, K. Harms, unpublished results.
[3] Cyclopropyl effect: If an acceptor substituent X stabilizes a neighboring
negative charge mainly by delocalization involving formation of a n
bond, then the cyclopropyl compound CJH,-X is less acidic than the
corresponding isopropyl compound C,H,-X, even though cyclopropane is more acidic than propane. Cause: The exocyclic n bond in the
three-membered ring “anion” causes an additional strain of ca. 13 kcal
mol- ’. For a different kind of stabilization, the cyclopropyl compound
is more acidic 161.
141 H. E. Zimmerman, B. S. Thyagarajan, J . Am. Chem SOC. 82 (1960)
[S] A. Ratajczak, F. A. L. Anet, D. H. Cram, J . Am. Chem. SOC.89 (1967)
2072; these authors observed dynamic NMR phenomena for dissolved
2,2-dimethyl-l-(phenylsulfonyl)cyclopropylIithium.They emphasized.
however, that this is insufficient evidence to assign the a-C atom a tetrahedral configuration, since the dynamic effects might be due to hindered
rotation of the sulfonyl group around the C-S axis of an anion having
an a-C atom with a planar configuration.
161 W. T. van Wijnen, H. Steinberg, T. J . DeBoer, Tetrahedron 28 (1972)
5423, and literature cited therein.
171 W. Kirmse, U. Mrotzeck, J . Chem. SOC.Chem. Commun. 1987. 710.
181 a) F. G. Bordwell, N. R. Vanier, M. S. Matthews, J. B. Hendrickson, P.
L. Skipper. J . Am. Chem. Soc. 97 (1975) 7160; b) F. G. Bordwell, J. C.
Branca, C. R. Johnson, N. R. Vanier, J. Org. Chem. 45 (1980) 3884.
191 R. Lett, G. Chassaing, A. Marquet, J . Organomet. Chem. 111 (1976)
C 17; see also [Ic].
[lo] D. A. Bors, A. Streitwieser, Jr., J . Am. Chem. SOC.108 (1986) 1397. The
stabilization occurs by n-o* interaction; see also S. Wolfe in F. Bernardi, 1. G. Csizmadia, A. Mangini (Eds.): Organic SuIfur Chemistry (Studies in Orgonrc Chemistry. Vol. 19). Elsevier, Amsterdam 1985, p. 133.
[I I] E. Keller, SCHAKAL 86, Freiburg 1986.
[I21 G. M. Sheldrick, SHELXS-86, Gbttingen 1986.
[I31 G. M. Sheldrick, SHELX-76, Cambridge 1976.
(100 mg,
1141 Preparation of 1 : 2,2-diphenyl-l-phenylsulfonylcyclopropane
0.30 mmol) in dimethoxyethane (2.0 mL) was treated with n-BuLi
(0.33 mmol) in hexane (0.19 mL) at 0°C. After 10 min, the solution was
evaporated to approximately 0.5 mL under oil-pump vacuum and allowed to stand at -30°C for ca. 12 h. Crystals suitable for X-ray analysis thereby formed. Yield: 65 mg (46%).
[ I 51 Interestingly, similar bonding is found in triphenylphosphoniocyclopropanide, in which the triphenylphosphane group is bent out of the plane
of the three-membered ring atoms by 58”: H. Schmidbaur, A. Schier, B.
Milewski-Mahrla, U. Schubert, Chem. Ber. 115 (1982) 722.
[I61 a) I. Reichelt, H.-U. Reissig, Liebigs Ann. Chem. 1984. 531, and references cited therein; b) R. Haner, T. Maetzke, D. Seebach, Helu. Chim.
ACIU69 (1986) 1655, and references cited therein; c) G. Boche, H. M.
Walborsky in Z. Rappoport (Ed.): The Chemistrv of the Cyclopropyl
Group. Wiley, Chichester 1987, p. 701.
1171 J. Kai, P. Knochel, S. Kwiatkowski, J. D. Dunitz, J. F. M. Oth, D. Seebach, H.-0. Kalinowski, Helu. Chrm. ACIU65 (1982) 137; see also (16cI.
1181 We have also found a tetrahedral coordination at an a-C atom and Li
coordination t o this atom for [l-cyano-2,2-dimethyIcyclopropyllithium(THF)],, a cyano-substituted cyclopropyl “anion”: M. Marsch, K.
Harms, G. Boche, unpublished results. This is in accordance with the
observation that the cyano group stabilizes a negative charge primarily
through the inductive (field) effect: see also G. Boche, M. Marsch, K.
Harms, Angew. Chem. 98 (1986) 373; Angew. Chem. Int. Ed. Engl. 25
(1986) 373, and references cited therein.
1191 Reactions with a-sulfonylcyclopropyllithiumcompounds: A. Padwa, M.
W. Wannamaker, A. D. Dyszlewski, J . Org. Chem. 52 (1987) 4760, and
references cited therein.
1201 Note added in proof (May 5 , 1988): A remarkably pyramidalized a-C
atom has been found in the case of [(phenylsulfonyl)isopropyllithium.diglymel2, the two methyl groups being bent out of planarity
(away from the 0 atoms of the C6H5S02group) by 23.6 and 27.1 (H.-J.
Gais, J. Vollhardt, G . Hellmann, H. Paulus, H. J. Lindner, Tetrahedron
Lett. 29 (1988) 1259).
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investigation, structure, уcarbanionф, cyclopropyllithiumцdimethoxyethane, atom, configuration, phenylsulfonyl, sulfonyl, ray, tetrahedral, diphenyl
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