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Diastereoselective Formation of Substituted (3-Allyl)(4-diene)ZrCp Complexes by Intramolecular Ligand Interaction.

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121 J. Weiser, Diplomarbeit, Universitat Heidelberg 1982-83.
[3] G. Schill, Justus Liebigs Ann. Chem. 691 (1966) 79.
[41 Elemental analyses and spectroscopic data are in accordance with the
ny1)zirconium l a , the hydrogen atoms at C-2 of the diene
and in the syn-position at C-5 of the allyl ligand come spatially very close (see Scheme 1); with respect to the C-2, Csuggested structures.
[51 A. D. Adler, F. R. Longo, W. Shergalis, J . Am. Chem. Soc. 86(1964) 3145;
5 vector they are almost eclipsed. The introduction of subA. D. Adler, F. R. Longo, J. D. Finarelli, J. Goldmacher, J. Assour, L.
stituents at these positions leads to the formation of diaKorsakoff, J . Org. Chem. 32 (1967)476.
stereomers. A strong repulsive interaction between these li[61 M. Momenteau, B. Loock, J . Mispelter, E. Bisagni, Nouu. J. Chim. 3
gands should result in a prererential occurrence of anti-1
(1979)77.
[71 Compound C:violet microcrystals, m.p. =296-297"C (from dichloromeover syn-1 under equilibrium conditions. We could dethane/methanol; MS: m/z 1106 (Ma, loo%), 1092 (2), 1078 (7), 553
monstrate this effect by introduction of methyl groups at
(M0/2, 30); ' H - N M R (360 MHz, CD2C12); 6 = -2.81 ( s , 2H), 0.78-1.44
(m, 14H),1.73-1.89(m,4H),2.25(s,3H),2.29(s,3H),2.40-2.52(m,2H), the 2- and 5-positions to give the (q4-isoprene)(q3-1-methylal1yl)ZrCp system l b / 2 b .
2.56-2.73(m, ]OH), 2.75-2.85(m, 2H),3.67 (s, 6H), 5.40 (s, 1 H), 5.43 (s,
lH),6.23(~,2H),7.39-7.48('dd',J=7.5Hz,4H),7.68-7.80(m,12H),8.46
Ib/2b was synthesized via the route previously de(s, 4 H),8.49 (s, 4 H).
CpZrCI, 3I5]is allowed to react
scribed by us for la/2a'3341:
with 2-butenylmagnesium chloride 4 ; subsequent comproportionation with two equivalents of the starting material
and reaction with "isoprene-magnesium" 7[61gives l b / 2 b
Diastereoselective Formation of
in ca. 10% total yield as a red solid which is very sensitive
Substituted (q3-Allyl)(q4-diene)ZrCp Complexes
to air and moisture. The material isolated at room temperby Intramolecular Ligand Interaction**
ature is photolyzed (Philips HPK 125, Pyrex filter) in toluene ( ~ 5 %solution) at -50°C; the compounds syn-2b
By Gerhard Erker*, Klaus Berg, Reinhard Benn, and
and anti-2b are obtained in a 45 : 55 ratio ('H-NMR). Both
Gerhard Schroth
Most of the catalysts in use today have been developed
empirically. However, there has been no lack of attempts
to synthesize homogeneous catalysts according to plan"].
A basic problem in directed syntheses is the control of selectivity. A prerequisite for a specific product formation at
the metal center is a pronounced intramolecular interacanti- l c
anti-2c
6 0 : 40
syn-2c
tion between different ligandsL2'.We have recently syntheI
sized the isomeric (q3-a11yl)(q4-diene)ZrCp complexes 1
and 213], which, because of the different arrangement of
the three n-ligands, can be expected to exhibit different inH3C
tramolecular ligand interactions.
H 3 C 4'r,2 r - C p
H3 c
0
II
/
anti- I d
,
7
hu
> 95%
C H3
anti-2d
c H3
55 : 45
syn-2d
Scheme 2
\
'
R
R
a, R = H; b , R = CH3
>9570 a n t i - l b
\
anti-2b
55 : 4 5
syn-2b
Scheme 1.
In the thermodynamically more stable isomer 1 the q3allyl and q4-diene moieties open towards the apical cyclopentadienyl (Cp) ligand. According to an X-ray structure
analysis and the 'H-NMR-NOE difference spectra of the
parent system[3] (q3-allyl)(q4-butadiene)(q5-cyclopentadie-
isomers rearrange on heating-within the range of accuracy of the measurement ('H-NMR) at equal rates
(AGkec= 21.7 k 0.3 kcal/mol)-to
give essentially one
product (diastereoselectivity > 95%), which according to
the N M R analysis is the expected isomer ~ n t i - l b [ ' . ~ ~ .
This effect is not limited to the system l b / 2 b . The (1,ldimethylallyl)(isoprene)ZrCp system lc/2c as well as (1,2dimethylallyl)(isoprene)ZrCp l d / 2 d , readily available
therefrom by a thermally induced hydrogen-shift, behave
analogouslyLg1.
The formation of the photoisomers 2c and
2d, in which the ally1 and diene moieties open towards the
basis of the skeletal framework, is unselective. The thermal
rearrangement affords only the thermodynamically more
stable diastereomers anti-lc and anti-ld, respectively.
Therefore, it seems promising to us to attempt the development of catalyst systems for stereoselective syntheses using the chiral building blocks (q3-I-methylallyl)ZrCp, (q4i s ~ p r e n e ) Z r C p ' ~or~ ]metal-complex fragments of similar
structure" 'I.
Received: May 8, 1984 [Z823 IE]
German version: Angew. Chem. 96 (1984)621
[*I Priv.-Doz. Dr. G. Erker, K. Berg,
Dr. R. Benn [+I,G. SchrothI'[
Max-Planck-lnstitut fur Kohlenforschung
Kaiser-Wiihelm-Platz 1, D-4330 Mulheim a. d. Ruhr (FRG)
I'[ NMR spectroscopic investigations.
[**I This work was supported by the Deutsche Forschungsgemeinschaft and
the Fonds der Chemischen Industrie.
Angew. Chem. I n / . Ed. Engl. 23 (1984) No. 8
[I] G. Wilke, J. Organomet. Chem. 200 (1980) 349; H. Brunner, Angew.
Chem. 95 (1983) 921;Angew. Chim. In/. Ed. Engl. 22 (1983) 897, and
references cited therein.
[2] H. Brunner, R. Lukas, Chem. Ber. 112 (1979) 2528; M. G. Reisner, I.
Bernal, J . Organornet. Chem. 220 (1981)55.
0 Verlag Chemie GmbH. 0-6940 Weinheim, 1984
OS70-0833/84/OXOR-0625 $ 02.50/0
625
[3] a) G. Erker, K. Berg, C. Kruger, G. Muller, K. Angermund, R. Benn, G.
Schroth, Angew. Chem. 96 (1984) 445; Angew. Chem. Int. Ed. Engl. 23
(1984) 455; b) G. Erker, K. Berg, R. Benn, G. Schroth, Chem. Ber. 1984,
in press.
[4] K. Berg, G. Erker, J. Organomel. Chem. 263 (1984) 37.
[5] G. Erker, K. Berg, L. Treschanke, K. Engel, Inorg. Chem. 21 (1982)
1277; L. M. Engelhardt, R. 1. Papasergio, C. L. Raston, A. H. White, Organometailics 3 (1984) 18.
[6] H. Yasuda, Y. Kajihara, K. Mashima, K. Nagasuna, K. Lee, A. Nakamum, Organometaliics 1 (1982) 388; see also: K. Fujita, Y. Ohnuma,
H. Yasuda, H. Tani, J. Organomet. Chem. 113 (1976) 201; U. Dorf, K.
Engel, G. Erker, Organomeraliics 2 (1983) 462.
[7] 'H-NMR (400 MHz, [D,]toluene, 6 values, rel. TMS): anti-lb (300 K):
Cp: 6.12; isoprene: -0.83 (anti-1-H), 2.02 (syn-I-H), 1.87 (s, C-2-CH3);
5.39 (3-H), -0.47 (anti-4-H), 1.58 (syn-4-H); allyl: 2.16 (anti-5-H), 1.43
(d, 5 , s Hz, C-5-CH,), 5.76 (6-H), 0.89 (anti-7-H). Selected coupling constants [Hz]: J(syn- I-H, anti-I-H), J(syn-4-H, anti-4-H)=7.5, J(anfi-5H,6-H)= 14.1, J(6-H, anti-7-H)= 13.2, J(6-H, syn-7-H)=9.4.--anti-Zb
(223 K, same sequence): Cp: 4.76; isoprene; - 1.84, 3.60, 1.89 (CH,),
4.96, -0.88, 3.03; allyl: 1.36, 1.94 (CH,), 5.84, 1.21, 2.88.-syn-Zb
(223 K): Cp: 4.75; isoprene: - 1.55, 3.28, 1.96 (CH,), 4.96, - 1.29, 3.46;
allyl: 1.89, 2.01 (CH,), 5.80, 0.70, 2.90. The positional data syn and anti
for the H atoms in positions 1/4 and 517 are with respect to the H atoms
2/3 and 6, respectively.
[S] Ca. 5% by-products ('H-NMR) among which the compound syn-lb
could so far not be identified with certainty.
191 The synthesis of these compounds: K. Berg, G. Erker, J . Organomet.
Chem. (1984), in press.
[I01 'H-NMR (400 MHz), [D&oluene, 6 values, rel. TMS, for sequence see
[7]): anti-lc (300 K): Cp: 6.02; isoprene: -0.84, 1.89, 1.86 (CH,), 5.49,
-0.15, 1.85; allyl 1.02 (anfi-C-5-CHz), 1.67 (syn-C-5-CH3), 5.56, 1.25,
I.OO.-anti-ld (300 K): Cp: 6.00; isoprene: -0.87,2.14, 1.82 (CH,), 5.06,
0.09, 1.79; allyl: 2.05, 1.42 (d, 5.7 Hz, syn-C-5-CH,), 1.96 (C-6-CH3),
1.14, 1.18.
[I I] A similar control of diastereomer formation has been described for an
analogously structured bis(+isoprene)(phosphane)iron(o) system : S . D.
Ittel, F. A. Van-Catledge, J. P. Jesson, J. Am. Chem. SOC.101 (1979)
3874.
Complexation of PhAs=CH2 and
Synthesis of a Novel RhAs3-Metallaheterocycle**
By Helmut Werner*, Wirfried Paul, and RarfZolk
So far only one methylenephosphane RP=CH2, the extremely reactive compound with R = 2,4,6-tBu3C6H2, is
known['"]. Analogous compounds R-E=CR; with R'= tBu
or OSiMe, were first prepared and structurally characterized by Becker et al.[lbl, and subsequently also by other
groups['c1. With regard to their stability, particularly for
methylenearsanes R-As=CR2, it appears that an almost
complete shielding of the polar As=C bond by bulky
groups R is of great importance. Convincing support for
this statement comes from the work of Bickelhaupt et a1.[21,
who observed a striking difference in reactivity between
(2,4,6-Me3C6H2)As=CPhz,which is stable at room temperature, and Ph-As=CPh2, which immediately polymerizes
under the same conditions.
Following the same method of synthesis which recently
enabled us to prepare thio-, seleno- and telluroformaldehyde complexes of cobalt and rhodiumL3],we have now
succeeded in generating and stabilizing Ph-As=CH2, a
compound unknown in the free state, in the coordination
sphere of a transition metal. The synthesis makes use of
complex 1, formed from C5MeSRh(C0)2and CH21,[3c1.1
reacts with L ~ A s H P ~ ' in
~ " Et,O/tetrahydrofuran
]
at room
temperature to produce 2f5al.Evidence for the proposed
~
[*I Prof. Dr. H. Werner, W. Paul, R. Zolk
Institut fur Anorganische Chemie der Universitat
Am Hubland, D-8700 Wurzburg (FRG)
[**I This work was supported by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie, and by gifts of chemicals from Degussa AG.
626
0 Verlag Chemie GmbH, 0-6940 Weinheim, 1984
structure with an y2-coordination of the methylenearsane
via As and C emerges from the 'H-NMR
in
which two well separated signals for the CH,-protons are
observed, as in CsMe,Rh(q2-CH,Se)CO[3cl.
Ph
Reaction of 1 with LiPHPh[4h1follows a similar course.
Compound 3 has not as yet been characterized analytically, but on basis of the spectroscopic data there is no doubt
about its composition and structure. Bickelhaupt et a1.[6a,b1
as well as Nixon et a1.[6c,d1
have prepared complexes of Cr,
Mo, W, Rh, and Pt with (2,4,6-Me3C6H2)P=CPh2as ligand;
spectroscopic measurements and X-ray analysis showed in
nearly all cases that the diphenylmethylenephosphane molecule is linked only via phosphorus to the metal. Evidence
for coordination via P and C has been found only in
the platinum(0) complex [(2,4,6-Me3C6H2)P=CPhz]Pt
(PhZPCH,)3CMe[6e1 and in the nickel complexes
[(2,6-MeZC6H3)P=CPh,]Ni(bpy)[6" and [(Me,Si),HCP=
C(SiMe,),]Ni(PMe3)J6g1,in which, as in 3, an electron-rich
metal is present.
Attempts to obtain single crystals of 2 from pentane led
to a yellow microcrystalline powder (2 according to mass
spectroscopy) as well as to some orange-red crystals 4,
which are formed from 2'5h1.
At preseh, no detailed mechanism for the formation of 4 can be formulated. The X-ray
structure analysis (Fig. 1)"' shows the presence of a nonplanar, four-membered RhAs,-ring in which the angle between the planes Rh, Asl, As2 and Rh, As3, As2 is 25.9"
and that between the planes Rh, AsI, As3 and Asl, As2,
As3 is 23.1'. The As-As distances correspond to single
bonds and are only slightly different from those in cyclo( A s C F ~ )(245.4(
~
1) pm)['"] and cyclo-(AsPh,) (average distance 245.9 pm)[8b1.The angle Asl-As2-As3 (82.97(5)") is
also similar to that in cyclo-(AsCF3), (83.6(1)").
As
1 A' s
ph
1
4
\
Ph
4 is the second example of a heterocycle derived from a
cy~lo-(AsR)~
ring system in which one AsR unit is replaced
by a transition metal moiety (C5Me,(CO)Rh). The first example was described by Kopf and Gorges, who isolated the
complex (C,H,),T~(ASE~)~I~'~.
More recently, Shaver et al.
reported the synthesis and crystal structure of the compound (C5Me5)2TiS3,which also contains a four-membered ring (though somewhat more bent than in 4)formed
from one transition-metal and three non-metallic
atoms["].
0570-0833/84/0808-0626 $ 02.50/0
Anqew. Chem. Int. Ed. Engl. 23 (1984) No. 8
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ally, diastereoselective, zrcp, intramolecular, diener, formation, interactiv, complexes, substituted, ligand
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