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[I31 In the IR and Raman spectra. apart from the typical bands for C,Ph, ligands.
only three additional bands are observed: v,.(FeCp,)425 c m - ' (IR). v,(FeCp,)
2 9 0 c n - ' (IR). h(FeCp,j 170cm-' (Raman) [ I l l .
1141 M. _I. Heeg. R. H. Herber. C. Janiak. J. 1. Zuckerman. H. Schumann. W. F.
Manders. J Orgunomel. C'iienr. 1988. 346. 321 -337.
[15] S. P. Gubin. S. A. Smirnova. L. I Denisovich, A . A. Lubovich, J. Organomei.
CIwnf 1971. 30, 243 -255.
[16] P. Zanello. A. Cinquantini. S. Mangani. G. Opromolla. L. Pardi, C. Janiak.
M. D. Rauscli. J O r g m ~ n n i 'Clwni..
in press: C. Janiak. personal communtcation
[I71 Ci. L . K. Hoh. W. E. McEwen. J. Kleinberg. J. Atn. Chiw. Soc. 1961, 83. 3949.
[I81 a ) C -,,HI,,BF,Fe.C,H,CI, (3): !b/ = 1203.68. crystal dimensions 0.23 x 0.10 x
0.10 mm'. tricltnic. Pi (no. 2). u =1346.7(7). h =1732.2(5). c = 1322.1(3) pm,
x =107.00(2). /I =100.80(3), 7 =74.00(4) V = 2815(2) x 10-3"m3, Z = 2,
( J ~ , , , ' ~= 1.32
1' = 4.51 c m - ' . Enraf-Nonius CAD4 diffractometer,
C u h X rxliatioii. .; =?1.069 pm. graphite monochromator. T = 190 K. 1 I
7 0 s 35 7681 measured reflections. of which 6131 were independent
(R,,,,= 0.02X0), 3756 observed reflections with ( F , ) 2 4u(.5,). solution bq direct
methods and structure refinement with SHELX76. absorption correction
(DIkABS. inin. 0.733, max. 1.369). R = 0.086. Rw = 0.094 (a. =l;u2(Fo)).refinement of all non-hydrogen atoms mostly anisotropic. otherwise isotropic,
the positions of the H atoms were calculated [18]. Rotational disorder of the F
atoms F2. F3. and F4 in the BF, anion could be established by refinement of
thc population factors F?. F3. F4 and F2a, F3a. F4a with approximately
0.4') 0.51, b ) Further details of the crystal structure investigation may he obtaiiicd from the Fachinformationszentrum Karlsruhe. D-76344 EggensteinLeopoldshafen ( F R G ) on quoting the depository number CSD-58235.
Thus, treatment of the bis(ethyltetramethylcyclopentadieny1)ytterbium complex 1 with the imidazol-2-ylidenes 2 leads to
the corresponding organolanthanoid-carbene adducts 3 in
good yields. Compounds 3 are thermally very stable (decomposition temperature at 0.1 mbar for 3 a is 229°C and 155 'C for
3b) and can be isolated as black crystals. They are soluble in
relatively polar and aromatic solvents such as tetrahydrofuran,
diethyl ether, toluene, and benzene. In contrast. they are only
sparingly soluble in hexane or pentane. Both products 3 are
considerably more stable to air and moisture than 1 .
Organolanthanoid-Carbene-Adducts" *
H e r b e r t Schumann*, Mario Glanz, Jorn Winterfeld,
Holger Hemling, N o r b e r t K u h n , * und Thomas Kratz
Dedicxileu' to Profbssor Ekkehardt Lindner
on the occurion o f his 60th bivtlzdaj,
Carbenes usually exhibit acceptor properties as ligands and
are most often dependent on classic backbonding for the formation of stable metal complexes. For this reason lanthanoid
metals with their 4f electrons, which lie deep in the inside of the
electron shell and thus hardly participate in bonding, are considered to be very poor coordination partners for carbenes. The
reports that have recently appeared on stable derivatives of imida~ol-7-ylidene['~
open up new possibilities due to the nucleophilic character of these compounds. The successful synthesis of
stable adducts with iodine,[2] tellurium,[31selenium,[41and, in
particular, the bond formation to electron-deficient centers such
as Ge12.['] AIH3,[61and BH3[?] gave the impression that it
should also be possible to prepare lanthanoid carbene complexes.[*] Particularly suitable for this should be oligomethylated
bis(cyclopentadienyl)samarium(~~),-europium(ri), and -ytterbium(n) derivatives. which can not only alter the oxidation
state,["- "1 but also have enough space for a sterically demanding third ligand because of their bent structure.
Y b - 0 3
2a R = M e
3a R = M e
2b R = fPr
3b R
The chemical shifts in the ' H and I3C N M R spectra of 3 a and
3b are as expected and are not significantly different from the
data of complex 1 and those of the carbenes 2. These results and
the intense dark color of the isolated adducts clearly show that
quasi-coordinative Yb"-C bonds are present in 3 and that 3a
and 3b are not paramagnetic Yb"' compounds. The I3C NMR
spectrum also indicates a new quality of the metal carbene interactions, since in 3, in contrast to the ylidene complexes of I,, Se,
Te, GeI,, BH,, and AIH,.[2-71 the carbene carbon atom is
slightly shifted for the first time to higher field by about 8 ppm.
The electron impact (70 eV) mass spectra of 3a and 3b show
no peak for the molecular ion; only several peaks for metal -carbene fragments occur in addition to the expected signals for
[(C,Me,Et)Yb]+ and [(C,Me,Et),Yb] * .
In the crystal the ylidene forms a planar five-membered ring,
the plane of which to a good approximation also contains all the
atoms bound to the heterocycle (Fig. 1 ) . Alternating bond
lengths, which are also observed in other complexes, occur within the carbene ring; however, here they are not so pronounced.[71Whereas the C 13-N (1.387(5) A) distance indicates
[*I Prof Dr H. Schuniann. Dr. M. Glanz. Di-. J. Wintei-feld, Dr. H. Hemling
I n s t i t t i l fur Aiiorganische und
Analytische Chemie der Technischen UniversitZt
Strassz des 17 Juni 1.15. 0-10623 Berlin (FRG)
Teletix: I n t code + (30j314-22168
Prof. Or. K. Kuhn, Dipl.-Chem. T. Kratz
Iiislttut fur Aiiorganische Chemie der Universitit
A u t der Morgenstelle 18, D-72076 Tiibingen (FRG)
Or$anomet:illic Compounds of Lanthanoids. Part 86. Thi5 work was supported h> the Deutsche Forschungsgemeinschaft. the Fonds der Chemischen Induhtrie. and the Bundesministerium fur Bildung und Wissenschaft (Graduiertenkolleg ..Synthese und Strukturaufkliirung niederinolekularer Verbindungen"). Part 8 5 . H. Schumann. J. Winterfeld. M. Glanz. R. D. Kohn. H. Hemling. .I. O~~:un~irirc!.
C / ~ e m in
. . press.
Fig. 1 . Crystal structure of 3 a (ORTEP [IZ]. thermal ellipsoids d r a a n a t 50%
probability level (the atom positions produced by symmetry operations [- v, y.
1.5-:] are not shown). Selected distances
and angles [ ] (standard deviations are
given in parentheses) [13]: Y b - C l 2.669(4), Y b CZ 2.692(4). Y b - C 3 2 688(4),
Y b b C 4 2.6?1(4). Yb C 5 2.648(3). Yb-C1Z 2.552(4); Cp-Yb-Cp 144.0(4). CpYb-C 12 107.5(4).
a formal single bond, the distances C 13-C 13' (1.358( 1 1) A) and
C 12-N (1.362(4) A) are shorter and lie in the range expected for
double bonds. The exocyclic C-C (1.489(6) A) and N-C bonds
(1.453(6) A) of the yIidene,['l and the Yb-C distances to the
cyclopentadienyl ligand'"1 (average 2.674(4) A) as well as the
Cp-Yb-Cp and Cp-Yb-C 12 angles['I correspond to the expected values. The Yb-C 12 bond length is appropriate for an extended single bond and is slightly longer than the corresponding
distances in [{Cp2Yb(p-Me)),](2.49 A, 2.54 A);[''] however, it
is significantly shorter than the corresponding bonds in
[CpTYb(p-Me)BeCp*] (2.77 A)["] or [Cp,*Yb(pEt)AlEt,(thf)]
(2.85 A) ." *I This illustrates the problems associated with the
discussion of the structure in comparison to classic carbene
complexes. Whereas the nearly trigonal-planar configuration of
the C 12 atom. which almost corresponds to sp2 hybridization.
and the p,-p, interactions in the bonds C 12-N can be interpreted as characteristic features of a carbene complex, the Yb-C 12
distance does not fit into the range expected for a double bond.
As a consequence of the lack of Yb-C backbonding, 3a and 3 b
can be considered as Fischer-type carbene adducts of
organolanthanoid(r1) compounds.
E.xpriiizerrtal Proceclure
Compound I was obtained analogously to CprYb 191. and 2a. b were prepared
according to literature [I]. The NMR spectra were recorded with a Bruker AMX
200 spectrometer at 200 MHz ( ' H ) o r 50.32 M H r ("C).
3a: 2a (0.16 g, 1 3 mmolj in T H F ( 5 mLj *as added dropwise to a solution of 1
measurement parameters: Enraf-Nonius CAD-4 diffractometer. T = 150(2) K.
i =71.069 pm (Mo,,). graphite monochromator. [ i = 3.323 m m - ' . R-211.
4 5 2 8 5 65 ; 2690 measured, 2689 independent (R,,, = 0.0063). 2639 ohserved reflections (IFo/> 4u1F01, corrections: Lorentr. polariration. decay
(min: 1.000. max: 1.010). DlFABS (min: 0.819, max: 1.256). solution: Patterson (SHELX-86 [I41j , difference Fourier (SHELX-93 [IS]) all non-hydrogen
atoms anisotropic. all hydrogen positions calculated isotropically (u,,,,,, =
0.08 A2), q l : max 0.609. min -0.X57 A': refined parameters: 146. R1 =
xllki,l - ~ ~ ~ = 0.0175,
~ ~ ~ irR2
~ = [~Z I IF. ( Fo: - F ~
l ) ~ . ~ I I , (=F0.0424.
Further details of the crystal structure i n ~ s t i g a t i o nmay he obtained from the
Fachinformations~entruin Karlsruhe. D-76344 Eggenstein-Leopoldshafen
( F R G j on quoting the depository number CSD-58277.
1151 G. M. Sheldrick. SHELX-93, Program for Crystal Structure Determination,
Univesitiit Giittingen. 1993.
[16] J. Holton. M. F. Lappert. D. G. H. Ballard, R. Pearce, J. L. Atwood. W. E.
Hunter, J C'licwi. .Tor.. Cheni. Coriiniim. 1976, 480-481.
[17] C. J. Burns, R . A. Anderseu. J. A m Cheni. Sot.. 1987. 108. 5853-5855.
[I81 H. Yamamoto. H. Ydsuda. K. Yokota, A. Nakamura. Y Kai. N. Kasai. Chern.
Lcrr. 1988, 1963 ~ 1 9 6 6 .
Regio- and Stereoselective Electrophilic
C-Substitution of
2-(N,N-Dibenzylamino)- 1,o-alkanediols
by Lithiation of Their Carbamates**
Walter Guarnieri, M a t t h i a s Grehl, and Dieter Hoppe *
(0.68 g. 1.2 mmol) in T H F (40mL) at -30 C and stirred for I?. h ;it 25 C. The
solvent was removed under wcuum, the residue washed with hexane (15 mL) and
suspended in toluene (40 mL). The clear solution was concentrated to 20 mL from
which black crystals of 3a were obtained at -25'C.
Drdicated to Prqfessor Werner Tochtermann
on the occcisioti q f his 60th hirthdaj,
Yield 0.63 g (80'%j: m.p. (0.1 mbar) 2 2 9 ' 6 . ' H N M R ([DJTHF): 6 = 3.37 (s. 6H.
NCH,). 2.48 (q. 4H. C,CfI,CH,j, 2.08 (s. 6H. CCH,), 1.84 (s, 12H. C,CH,). 1.82
( 5 , 12H. C,CH,j. 0.86 ( t , 6H. C,CH,CH,j; I3C N M R ([DJTHF): ii = 205.0 (:Cj.
125.8 (C'CH,). 119.0 (C,CH,CH,). 111.8 (C,CH,j. 111.1 (C,CH,). 35.9 (NCH,).
19.8 (C,C'H,CH,j. 16.7 (C,CH,CH,j. 10.9 (C5CH3).10.X (C,C'H,j. 8.6 (CCH,).
Correct elemental analysis for CZ,H,,N2Yb (595.74).
Enantiomerically pure fi-amino-a-hydroxy acids and aminopolyols are becoming increasingly important for the synthesis of
enzyme inhibitors."] We report here on a simple and very flexible approach to these classes of compounds. The carbamate
derivatives 1 of (S)-2-(N,A'-dibenzylamino)-I
-alkanols can be
deprotonated at C-I by see-butyllithium to give the configurationally stable ion pairs 2 (El = Li) or 3 (El = Li), which react
with electrophiles stereospecifically with retention of configuration (Scheme I).['' Deprotonation in the presence of the achiral
additive N,N.N',N'-tetramethylethylenediamine (TMEDA,
variant A) is directed by the stereogenic center at C-2 and favors
the removal of the ( p r o - R ) proton H,; in contrast, in the presence of (-)-sparteine (variant B) H, is a b ~ t r a c t e d . [ ~ . ~ ]
3b: Analogously to 3a. 1 (0.31 g. 0.6 mmol) was treated w'ith Zb (0.10 g. 0.6 mmolj
and black crystals of 3b were obtained at -25 C. Yield 0.29 g (78%): m.p.
(0 1 mbar) 155 C. ' H NMR ( C , D , ) : 6 = 3.67 (sept. 2H. NCHCH,), 2.57 (q. 4H.
C,CH2CH,),2.18 (s. 12H. C,CH,),Z.I?(s. 12H.C5CH,j. 1.55(s.6H.CCH3). 1.22
(t. 6H. C,CH,CH,j, 1.17 (d. 12H. NCHCH,): ',C NMR (C,D,): 6 =198.1 (:C).
124.8 (C'CH,). 11X.9 (C',CH,CH,). 111.9 (C-CH,). 111.0 (C,CH,j, 49.7
(NCHCH,). 21.0 (NCHCH,). 20.5 (C,CH,CH,). 16.8 (C,CH,CH,). 12.0
(C,C'H,). 11.7 (C,C'H,j. 8.9 (C'CH,). Correct elemental analysis for C,,H,,N,Yb
Received: April 2, 1994 [Z6821 IE]
German version: A I I ~ C I I Clieni.
1994. 106. 1829
A. J. Arduengo 111. R. L. Harlow. M. Kline. J A i n C1wii. S o r . 1991. 113.
361 -363; A. J. Arduengo 111, H. V. R . Diar. R. L. Harlow. M. Kline, ;hid
1992. 114. 5530 5534: N. Kuhn. T. KratL. Swrhcs;.s 1993, 561 -562.
N . Kuhn, T. Kratz. G. Henkel. J C 1 i m S o r . (%em. Cnninnni. 1993. 17781779.
N. Kuhn. G. Henkel. T. Kratr. C/ieni. Bw. 1993, 126. 2047-2049.
N. Kuhn. G. Henkel, T. KratL. Z. A'ururforsch. B 1993. 48. 973-977.
A. J. Arduengo 111, H. V. R. Diar. J. C. Calabrese. F. Davidson. Inorg. Clirin.
1993, 32, 1541-1542.
A . J. Arduengo 111. H. V. R. Diaz, J. C. Calabrese. F. Davidson. J A m . C%eni.
Sor.. 1992. 114. 9724-9725.
N. Knhn. G Henkel. T Kratz, J. Kreutrberg. R. Boese. A. H. Mautlitr, C1ieiii.
Bcr.1993, 1 6 , 2041 -2045.
For the coordination ofimidazol-2-ylidenes to centers of d-block elements cf
K. Ofele. W A. Herrmann. D. Mihalios. M. Elison. E. Herdtweck. W. Scherer,
J. Mink, J. Organon?r/.Chen?.1993.4jY. 177-184; N. Kuhn. T. KratL. R. Boese.
D. Bliiser. ;bid 1994. 470 C8-Cll. and reference5 therein.
T. D. Tilley. R . A. Andersen, B. Spencer. H. Ruben. A. Zalkin. D. H. Templeton. nor^. c1I~~nl.
1980. I Y , 7999 3003.
W. J. Evans. L. A. Hughes. T. Hanusa. J. Am. C%em Sot.. 1984. 106.4270-4272.
W. J. Evans. L. A. Hughes. T. Hanusa. Or,~Nrioi,irrn//ir.\1986. 5. 1285 1291.
C. K. Johnson. ORTEP-11, Report ORNL-5138. Oak Ridge National Laboratory. TN, USA. 1976.
Crystal data: 0.6 x 1.5 x 1.5 mm. orthorhomic. ('222,. ( I = 11.366(3), / I =
15.953(4). ~.=14.990(4)A. P " 2 7 1 8 . 0 ( 1 2 ) ~ 3 .% = 4 . pLJ,cd
=1.451 gem-'.
L'CH I / i ~ r l u , ~ . r ~ ~ i ~ . ~mhH.
~ ~ l l \ ~1)-69453
Wr.inhihi, 1994
Scheme 1. Variant A: a) .sBuLi, TMEDA, Et,O, -78 ' C ; Variant B: b) sBuLi.
(-)-sparteine. Et,O. -78 ; c) electrophile EIX.
Prof. Dr. D. Hoppe. W. Guarnieri. Dr. M. Grehl"'
Organisch-chemisches Institut der Universitit
Corrensstrasse 40. D-48149 Miinster (FRG)
Telefax: Int. code + (251)83-9772
X-ray structure analysis
This research was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and the Pharma Research Center of Bayer
AG. Wuppertal.
Oj70-0833:Y4:17/7-1734 S 10.00+ .25,0
Anyew. Chern. I n t . Ed. Enyl. 1994, 33, N o . 17
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