An unprecedented [C2+C1+C1] coupling of an alkynyl, an allenylidene, and a CO unit: The formation of a highly unsaturated cyclobutenone derivative in the coordination sphere of rhodium(I)

Article abstract of DOI:10.1002/(SICI)1521-3773(20000218)39:4<786::AID-ANIE786>3.0.CO;2-R

Mono- and dinuclear organometallic rhodium(I) complexes such as 1 are obtained in excellent yields by the reaction of trans-[RhF{= C = C = C(Ph)R}(PiPr₃)₂] with triphenylstannanes PhC ? CSnPh₃ and Ph₃SnC ? CC ?

Full text of DOI:10.1002/(SICI)1521-3773(20000218)39:4<786::AID-ANIE786>3.0.CO;2-R

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supplementary publication no. CCDC-134036. Copies of the data can
be obtained free of charge on application to CCDC, 12 Union Road,
Cambridge CB21EZ (fax: (‡44)1223-336-033; e-mail: deposit@ccdc.
cam.ac.uk).
ˆ ˆ ˆ
complexes of the general composition trans-[RhR( C C
CR1R2)(PiPr3)2] failed,[4] we have now succeeded with the
preparation of the corresponding alkynyl(allenylidene) com-
1
2
ꢀ
ˆ ˆ ˆ
[8] The sum of the van der Waals radii of HgII and S is 3.53 Š: J. G.
Wright, M. J. Natan, F. M. MacDonnell, D. M. Ralston, T. V. OꢁHal-
loran, Prog. Inorg. Chem. 1990, 38, 323 ± 412.
pounds trans-[Rh(C CPh)( C C CR R )(PiPr3)2], one of
which undergoes an unprecedented [C2‡C1‡C1] coupling
reaction with CO to give a highly unsaturated cyclobutenone
derivative.
The synthetic route to the new alkynylrhodium(i) com-
plexes 5 and 6 is outlined in Scheme 1. In order to coordinate
the C2 unit to the metal center, the key to success was the use
[9] It is known that Hg C bonds are activated by suitable donor ligands,
for example in triphosphane complexes: P. Barbaro, F. Cecconi, C. A.
Ghilardi, S. Midollini, A. Orlandini, A. Vacca, Inorg. Chem. 1994, 33,
6163 ± 6170. Donor activation by the bacterial enzyme organomercury
lyase is also postulated in Hg C bond cleavage: M. J. Moore, M. D.
Distefano, L. D. Zydowsky, R. T. Cummings, C. T. Walsh, Acc. Chem.
Res. 1990, 23, 301 ± 308.
[10] H. A. Staab, H. Bauer, K. M. Schneider, Azolides in Organic Synthesis
and Biochemistry, WILEY-VCH, Weinheim, 1998, pp. 14 ± 16, 129 ±
140.
[11] A. von Döllen, H. Strasdeit, Eur. J. Inorg. Chem. 1998, 61 ± 66.
[12] G. Zuppiroli, C. Perchard, M. H. Baron, C. de Loze, J. Mol. Struct.
1981, 72, 131 ± 141.
[13] G. M. Sheldrick, SHELX-97, Universität Göttingen, 1997.
[14] DIAMONDÐVisual Crystal Structure Information System, Version
2.1, CRYSTAL IMPACT, Bonn, 1999.
An Unprecedented [C2‡C1‡C1] Coupling of
an Alkynyl, an Allenylidene, and a CO Unit:
The Formation of a Highly Unsaturated
Cyclobutenone Derivative in the Coordination
Sphere of Rhodium(i)**
Scheme 1. Synthesis of mono- and dinuclear rhodium(i) complexes 5 ± 8.
Juan Gil-Rubio, Birgit Weberndörfer, and
Helmut Werner*
[5]
ꢀ
of the mild transmetalating reagent PhC CSnPh3 and the
Dedicated to Professor Heinrich Vahrenkamp
on the occasion of his 60th birthday
highly reactive fluoro compounds 3 and 4. While the latter
could not be prepared by salt metathesis from trans-
ˆ ˆ ˆ
[RhCl{ C C C(R)Ph}(PiPr3)2] and KF or TlF, respectively,
Metal-assisted C C coupling reactions belong to the most
important processes in organometallic chemistry.[1] Following
our work on the synthesis of metal vinylidene compounds
from alkynes, we recently reported that the square-planar
they were obtained in excellent yield by treatment of the
hydroxo derivatives 1 and 2 with one equivalent of NEt3 ´ 3HF
in benzene. The fluoro complexes are green-yellow (3) and
green (4) crystalline solids that can be stored at room
temperature under argon and are stable for several days in
solution in C6D6. The 19F NMR spectra of 3 and 4 show the
expected pattern of signals with 103Rh ± 19F and 31P ± 19F
1
2
ˆ ˆ
rhodium complexes trans-[RhR( C CR R )(PiPr3)2] (R ˆ
methyl, vinyl, phenyl, alkynyl) undergo an intramolecular
C C coupling reaction in the presence of CO to give trans-
1
2
[2]
ˆ
[Rh{C(R) CR R }(CO)(PiPr3)2]. A related reaction occurs
2
couplings, the J(P,F) values of about 19 Hz being character-
istic for a cis disposition of the fluoro and the phosphane
ligands.[6]
ˆ ˆ ˆ
between the allenylidene compounds trans-[RhX( C C
CR1R2)(PiPr3)2] (X ˆ OAr, OC(O)Me, N3) and CO to give
1
2
ꢀ
the alkynyl complexes trans-[Rh(C C CXR R )(CO)-
(PiPr3)2], resulting from the migration of the group X to the
g-C atom of the allenylidene ligand.[3] While earlier attempts
from our laboratory to obtain alkyl, vinyl, or arylrhodium(i)
ꢀ
The reactions of 3 and 4 with PhC CSnPh3 resulted in the
formation of the alkynyl complexes 5 and 6 together with a
white, poorly soluble by-product which was identified as
Ph3SnF by comparison of its IR spectrum with that of an
authentic sample prepared from Ph3SnCl and KF.[7] Although
compounds 5 and 6 (which are violet and brown crystalline
solids, respectively) are more sensitive than the related fluoro
or hydroxo derivatives, they have been fully characterized on
the basis of their analytical and spectroscopic data. Besides
the single resonance in the 31P NMR spectra with a J(Rh,P)
coupling constant that is typical for a trans disposition of both
phosphorus atoms, the most characteristic features are the
[*] Prof. Dr. H. Werner, Dr. J. Gil-Rubio, Dipl.-Chem. B. Weberndörfer
Institut für Anorganische Chemie der Universität
Am Hubland, 97074 Würzburg (Germany)
Fax : (‡ 49)931-888-4605
E-mail: helmut.werner@mail.uni-wuerzburg.de
1
[**] This work was supported by the Deutsche Forschungsgemeinschaft
(Grant SFB 347), the Fonds der Chemischen Industrie, and the
European Commission (Contract ERBFMBICT960698).
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0570-0833/00/3904-0786 $ 17.50+.50/0
Angew. Chem. Int. Ed. 2000, 39, No. 4

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low-field signals for the allenylidene and the alkynyl ligands in
the 13C NMR spectra of 5 and 6. In particular, the resonances
for the a-carbon atoms of the allenylidene and the alkynyl
units (both doublets of triplets) can be clearly assigned owing
to the large 1J(Rh,C) coupling constants of about 53 and
40 Hz, respectively.
The high reactivity of the fluororhodium(i) compounds 3
and 4 is not only illustrated by the formation of 5 and 6 but
also by the synthesis of the dinuclear complexes 7 and 8
(Scheme 1). However, these compounds were not only
ꢀ
ꢀ
formed by treatment of 3 and 4 with Ph3SnC CC CSnPh3,
but even more conveniently by using the hydroxo derivatives
1 and 2 as starting materials. In this case the by-product is
Ph3SnOH, which can be easily separated from the less soluble
complexes 7 and 8 by washing with acetone. The 13C NMR
spectrum of compound 8 (which is more soluble in organic
solvents than 7) displays the expected signals for the
allenylidene and butadiynediyl ligands with the chemical
shifts and coupling constants similar to those of 6. Additional
structural support is provided by the mass spectra of 7 and 8,
which show in both cases the peaks of the molecular ions and
‡
the fragments [Rh{C3(R)Ph}(PiPr3)2] , respectively. In this
context we note that dinuclear transition metal complexes
containing a ªnakedº C4 bridge were recently prepared by
Gladysz et al.,[8] Lapinte et al.,[9] Bruce et al.,[10] and others
(including us)[5, 11] and investigated as promising candidates
for use in material science.[12]
Scheme 2. Synthesis and mechanism of the formation of 9. L ˆ PiPr3.
Since we knew that reactions of the vinylidene complexes
1
2
ꢀ
ˆ ˆ
trans-[Rh(C CR)( C CR R )(PiPr3)2] with CO give rise to a
migratory insertion of the vinylidene ligand into the Rh C s
bond,[2] we were interested to find out whether an analogous
reaction of 6 with CO would also occur. However, when a
stream of CO was passed through a suspension of 6 in hexane
at room temperature, a quantitative conversion of the alkynyl
derivative to the cyclic compound 9 took place (Scheme 2).
The result of the single-crystal X-ray diffraction study of 9
confirmed (Figure 1)[13] that quite unexpectedly two CO
molecules were involved in the formation of the novel C C
coupling product. One carbonyl group is coordinated to the
metal, while the other forms a four-membered ring together
with the two alkynyl carbon atoms and the a-carbon atom of
the allenylidene unit. The cyclobutenone ring is s-bonded to
the rhodium center by the a-C atom of the original alkynyl
ligand. The phenyl group at C3, the cyclobutenone ring, and
the cumulene unit are nearly coplanar, defining a plane which
lies almost perpendicular to the coordination plane around
the metal center. The dihedral angle between the two planes
[P1,P2,Rh,C1,C2] and [C2,C3,C4,C5] amounts to 89.7(1)8.
Owing to the molecular symmetry and the slow rotation
around the Rh C s bond, the two phosphorus nuclei are
chemically inequivalent and thus the 31P NMR spectrum of 9
displays a multiplet corresponding to the AB part of an ABX
system. We therefore assume that the molecular structure of 9
which was found in the crystal is also preserved in solution.
A possible mechanism for the conversion of 6 to 9 is shown
in Scheme 2. In the initial step, the starting material 6 reacts
with one molecule of CO to give the intermediate 10, which
contains a C5 chain resulting from the coupling of the
allenylidene and the alkynyl ligands. By carrying out the
Figure 1. Molecular structure of 9 in the crystal. Selected bond lengths [Š]
and angles [8]: Rh-C1 1.840(3), Rh-C2 2.030(3), Rh-P1 2.3439(9), Rh-P2
2.3347(9), O2-C4 1.209(3), C2-C3 1.392(4), C2-C5 1.511(4), C3-C4 1.458(4),
C3-C6 1.459(4), C4-C5 1.523(4), C5-C12 1.298(4), C12-C13 1.320(4); C1-
Rh-C2 173.38(13), C2-Rh-P1 90.83(8), C1-Rh-P2 89.06(10), C1-Rh-P1
89.72(10), C2-Rh-P2 91.51(8), P2-Rh-P1 170.14(3), C2-C3-C4 93.6(2), O1-
C1-Rh 175.6(3), C3-C2-Rh 132.7(2), C5-C2-Rh 135.8(2), C3-C2-C5 91.5(2),
O2-C4-C3 137.4(3), O2-C4-C5 134.0(3), C3-C4-C5 88.5(2), C12-C5-C2
140.9(3), C12-C5-C4 132.7(3), C2-C5-C4 86.4(2), C5-C12-C13 172.2(3).
reaction of 6 with one equivalent of CO at low temperature,
10 could be isolated as a yellow, thermally unstable solid. The
IR and 13C NMR data of 10 are similar to those of the related
1
ˆ
ˆ ˆ
four-coordinate compound trans-[Rh{h -C(CH CH2) C
CPh2}(CO)(PiPr3)2] which was obtained by treatment of
3
[4]
ˆ ˆ
[Rh(h -CH2CHC C CPh2)(PiPr3)2] with CO. The inter-
mediate 10 (which in C6D6 in the presence of CO affords
quantitatively the cyclobutenone derivative 9) could inter-
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0570-0833/00/3904-0787 $ 17.50+.50/0
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3
ꢀ
PCHCH3), 1.40 (dvt, N ˆ 13.5, J(H,H) ˆ 7.0 Hz, 36H, PCHCH3); 13C{1H}
convert with the isomer 11 through the interaction of the C C
NMR (100.6 MHz, C6D6): d ˆ 249.1 (dt, 2J(Rh,C) ˆ 10.2, 3J(P,C) ˆ 5.1 Hz,
bond with the rhodium center. An analogous equilibrium has
Rh C C), 233.5 (dt, 1J(Rh,C) ˆ 53.9, J(P,C) ˆ 17.3 Hz, Rh C), 158.6 (d,
2
ˆ ˆ
ˆ
1
ꢀ
ˆ
recently been observed between trans-[Rh{h -C(C CH)
CH2}(CO)(PiPr3)2] and trans-[Rh{h -CH C C CH2}(CO)-
2
4
ꢀ
ˆ ˆ ˆ
J(Rh,C) ˆ 8.1 Hz, Rh-C C), 156.0 (t, J(P,C) ˆ 2.6 Hz, Rh C C C), 118.6
1
ˆ ˆ ˆ
(dt, 1J(Rh,C) ˆ 40.7, J(P,C) ˆ 19.0 Hz, Rh C C), 25.9 (vt, N ˆ 19.3 Hz,
2
ꢀ
(PiPr3)2].[14] In a subsequent step, the reaction of 11 with a
second molecule of CO could give the acyl complex 12 which
undergoes an isomerization to 13 by an 1,3-shift of the
[Rh(CO)(PiPr3)2] fragment. The cyclobutenone derivative 9
could finally be generated by an intramolecular [2‡2] cyclo-
addition from 13. Although to the best of our knowledge there
is no precedent in organometallic chemistry for such an
isomerization reaction of 12 to 13, an analogous rearrange-
ment has been observed in the thermal interconversion of
acylallenes to vinylketenes by flash vacuum thermolysis.[15]
Regarding the formation of unsaturated four-membered rings
which are connected to an organometallic entity, we note that
the groups of Davison,[16] Kolobova,[17] Hughes,[18] and Fisch-
er[19] already reported the synthesis of cyclobutenylidene
complexes by [2‡2] cycloaddition of either cationic or neutral
vinylidene ± metal precursors and metal alkynyl complexes.
However, in this case the generated four-membered ring does
not contain an exocyclic C C double bond.
PCHCH3), 20.8 (s, PCHCH3); 31P{1H} NMR (162.0 MHz, C6D6): d ˆ 41.5
1
(d, J(Rh,P) ˆ 134.0 Hz).
Compound 6 was prepared in a similar way from 4 (296 mg, 0.48 mmol) and
PhC CSnPh3 (218 mg, 0.48 mmol); brown crystals; yield 242 mg (72%);
ꢀ
1
ꢀ
ˆ ˆ
m.p. 798C (decomp); IR (nujol): nÄ ˆ 2064 (C C), 1890 (C C C) cm
;
1H NMR (400 MHz, C6D6): d ˆ 2.82 (m, 6H, PCHCH3), 1.34 (dvt, N ˆ 13.2,
3J(H,H) ˆ 6.2 Hz, 36H, PCHCH3); 13C{1H} NMR (100.6 MHz, C6D6): d ˆ
1
2
2
ˆ
257.6 (dt, J(Rh,C) ˆ 51.9, J(P,C) ˆ 16.8 Hz, Rh C), 236.1 (dt, J(Rh,C) ˆ
3
4
ˆ ˆ
ˆ ˆ ˆ
2
12.2, J(P,C) ˆ 5.8 Hz, Rh C C), 156.3 (t, J(P,C) ˆ 3.0 Hz, Rh C C C),
2
1
ꢀ
153.5 (d, J(Rh,C) ˆ 9.2 Hz, Rh C C), 123.4 (dt, J(Rh,C) ˆ 39.7, J(P,C) ˆ
ꢀ
19.3 Hz, Rh C C), 25.8 (vt, N ˆ 19.3 Hz, PCHCH3), 20.8 (s, PCHCH3);
31P{1H} NMR (162.0 MHz, C6D6): d ˆ 43.9 (d, J(Rh,P) ˆ 133.9 Hz).
1
7: A solution of 1 (251 mg, 0.40 mmol) in THF (10 mL) was treated with
ꢀ
ꢀ
Ph3SnC CC CSnPh3 (149 mg, 0.20 mmol) at 788C. Under continuous
stirring, the mixture was slowly allowed to warm to room temperature and
stirred for 7 h. The resulting dark blue suspension was concentrated to
about 0.5 mL in vacuo and acetone (5 mL) was added. The solution was
filtered and the filtrate was evaporated to dryness in vacuo. The residue was
washed five times with 5 mL-portions of acetone and dried; yield 217 mg
ꢀ
(85%); m.p. 508C (decomp); IR (nujol): nÄ ˆ 1947 (C C), 1860
(C C C) cm 1; 1H NMR (200 MHz, CD2Cl2): d ˆ 2.77 (m, 12H, PCHCH3),
ˆ ˆ
1.21 (dvt, N ˆ 13.4, 3J(H,H) ˆ 6.4 Hz, 72H, PCHCH3); 31P{1H} NMR
(81.0 MHz, CD2Cl2): d ˆ 42.5 (d, 1J(Rh,P) ˆ 132.9 Hz); ESI MS (CH2Cl2/
‡
‡
CH3CN): m/z: 1275 [MH ], 613 [Rh{C3Ph2}(PiPr3)2 ].
Compound 8 was prepared in a similar way from 2 (310 mg, 0.51 mmol) and
Experimental Section
ꢀ
ꢀ
Ph3SnC CC CSnPh3 (190 mg, 0.25 mmol) in benzene (10 mL) at room
temperature; blue-violet solid; yield 202 mg (65%); m.p. 598C (decomp);
All experiments were carried out under argon. The NMR data of the
phenyl and tert-butyl groups are ommitted for clarity. Abbreviations: v ˆ
virtual coupling; N ˆ 3J(PH) ‡ 5J(PH) or 1J(PC) ‡ 3J(PC); w ˆ weak; m ˆ
medium; s ˆ strong.
3: A solution of 1 (458 mg, 0.73 mmol) in benzene (20 mL) was treated with
NEt3 ´ 3HF (40 mL, 0.25 mmol) at room temperature. The reaction mixture
was stirred for 1 h and evaporated to dryness in vacuo. The residue was
extracted four times with 20 mL-portions of pentane. The extract was
concentrated to about 4 mL in vacuo and then stored for 2 h at 258C. A
green-yellow microcrystalline solid precipitated which was washed three
times with 3 mL-portions of pentane ( 508C) and dried; yield 386 mg
IR (nujol): nÄ ˆ 1952 (C C), 1888, 1878 (C C C) cm 1; 1H NMR (400 MHz,
[D8]THF): d ˆ 2.69 (m, 12H, PCHCH3), 1.21 (dvt, N ˆ 13.5, 3J(H,H) ˆ
ꢀ
ˆ ˆ
6.4 Hz, 72H, PCHCH3); 13C{1H} NMR (100.6 MHz, [D]8THF): d ˆ 254.2
(dt, 1J(Rh,C) ˆ 51.9, J(P,C) ˆ 17.3 Hz, Rh C), 235.3 (dt, 2J(Rh,C) ˆ 11.2,
2
ˆ
3
4
ˆ ˆ
ˆ ˆ ˆ
J(P,C) ˆ 6.1 Hz, Rh C C), 156.0 (t, J(P,C) ˆ 3.1 Hz, Rh C C C), 149.8
1
2
ꢀ
ꢀ
(m, Rh C C), 133.7 (dt, J(Rh,C) ˆ 39.7, J(P,C) ˆ 19.3 Hz, Rh C C), 25.9
(vt, N ˆ 20.3 Hz, PCHCH3), 20.8 (s, PCHCH3); 31P{1H} NMR (162.0 MHz,
[D8]THF): d ˆ 44.4 (d, 1J(Rh,P) ˆ 133.9 Hz). ESI MS (CH2Cl2/CH3CN):
‡
‡
m/z: 1234 [M ], 593 [Rh{C3(tBu)Ph}(PiPr3)2 ].
9: A slow stream of CO was passed through a suspension of 6 (168 mg,
0.24 mmol) in hexane (6 mL) for 30 s at room temperature. The flask was
sealed and the mixture was stirred for 3 h. The resulting yellow-orange
suspension was concentrated to about 3 mL in vacuo and stored at 258C
for 3.5 h. A yellow solid precipitated which was washed twice with 2-mL
portions of pentane ( 788C) and dried; yield 172 mg (90%); m.p. 1618C
ˆ ˆ
(84%); m.p. 1128C (decomp); IR (nujol): nÄ ˆ 1871 (C C C), 475, 458
(Rh F) cm 1; 1H NMR (400 MHz, C6D6): d ˆ 2.74 (m, 6H, PCHCH3), 1.34
(dvt, N ˆ 13.5, 3J(H,H) ˆ 6.4 Hz, 36H, PCHCH3); 13C{1H} NMR
(100.6 MHz, C6D6): d ˆ 254.3 (dt, 2J(Rh,C) ˆ 14.2, 3J(P,C) ˆ 6.4 Hz,
ˆ ˆ
ˆ
ˆ ˆ ˆ
Rh C C), 230.6 (m, Rh C), 154.7 (s, Rh C C C), 23.5 (vt, N ˆ 19.3 Hz,
PCHCH3), 20.2 (s, PCHCH3); 19F NMR (188.3 MHz, C6D6): d ˆ 188.8 (dt,
1J(Rh,F) ˆ 23.0, 2J(P,F) ˆ 20.2 Hz); 31P{1H} NMR (162.0 MHz, C6D6): d ˆ
ˆ ˆ
(decomp); IR (nujol): nÄ ˆ 1955 (s), 1908 (w) (CO and C C C), 1734 (s),
1
ˆ
ˆ
1717 (s) (C O), 1596 (m), 1512 (m) (C C) cm
;
1H NMR (400 MHz,
1
2
C6D6): d ˆ 2.17, 1.94 (both m, 6H, PCHCH3), 1.26, 1.00, 0.92, 0.88 (all m,
41.5 (dd, J(Rh,P) ˆ 140.7, J(P,F) ˆ 18.7 Hz).
36H, PCHCH3); 13C{1H} NMR (100.6 MHz, C6D6): d ˆ 241.7 (dt,
Compound 4 was prepared in a similar way from 2 (274 mg, 0.45 mmol) and
NEt3 ´ 3HF (24.4 mL, 0.15 mmol); green crystals; yield 245 mg (89%); m.p.
1J(Rh,C) ˆ 33.2, 2J(P,C) ˆ 15.3 Hz, Rh C), 198.1 (dt, 1J(Rh,C) ˆ 53.9,
J(P,C) ˆ 15.0 Hz, Rh CO), 189.9 (s, C O), 181.3 (d, 3J(Rh,C) ˆ 2.7 Hz,
2
ˆ
ˆ ˆ
1028C (decomp); IR (nujol): nÄ ˆ 1890, 1879 (C C C), 473, 467, 449
C C C), 163.4 (t, J(P,C) ˆ 3.6 Hz, Rh C CPh), 129.5 (d, 2J(Rh,C) ˆ
3
ˆ ˆ
ˆ
(Rh F) cm 1; 1H NMR (400 MHz, C6D6): d ˆ 2.55 (m, 6H, PCHCH3), 1.29
(dvt, N ˆ 13.5, 3J(H,H) ˆ 6.4 Hz, 36H, PCHCH3); 13C{1H} NMR
ˆ ˆ
ˆ ˆ
1.8 Hz, C C C), 122.0 (s, C C C), 27.0, 26.6 (both vdd, J ˆ 15.3 and
5.4 Hz, PCHCH3), 20.9, 20.4, 19.6, 19.5 (all s, PCHCH3); 31P{1H} NMR
(162.0 MHz, C6D6): AB part of an ABX system, dA ˆ 47.3, dB ˆ 48.2
ˆ ˆ
ˆ
(100.6 MHz, C6D6): d ˆ 250.5 (m, Rh C C), 239.0 (m, Rh C), 154.9 (s,
Rh C C C), 23.1 (vt, N ˆ 18.1 Hz, PCHCH3), 20.1 (s, PCHCH3); 19F
ˆ ˆ ˆ
(1J(Rh,PA) ˆ 1J(Rh,PB) ˆ 135.7 Hz, J(PA,PB) ˆ 235.7 Hz).
2
NMR (376.4 MHz, C6D6): d ˆ 181.7 (dt, 1J(Rh,F) ˆ 2J(P,F) ˆ 20.3 Hz);
31P{1H} NMR (162.0 MHz, C6D6): d ˆ 43.1 (dd, J(Rh,P) ˆ 141.6, J(P,F) ˆ
1
2
10: Gaseous CO (ca. 0.1 mmol) was introduced into a schlenk flask
containing a suspension of 6 (69 mg, 0.01 mmol) in pentane (10 mL) at
788C. Under continuous stirring, the mixture was allowed to warm to
458C, stirred for 25 min and then evaporated to dryness in vacuo to give a
19.5 Hz).
5: A solution of 3 (285 mg, 0.45 mmol) in pentane (25 mL) was treated with
ꢀ
PhC CSnPh3 (203 mg, 0.45 mmol) and stirred for 2 h at room temperature.
ꢀ
yellow solid; IR (nujol): nÄ ˆ 2159 (m) (C C), 1969 (w), 1947 (s), 1902 (w),
A dark red-violet suspension was formed, which was filtered through a
cotton pad. The filtrate was evaporated to dryness in vacuo and the residue
was extracted four times with 10 mL-portions of pentane. The combined
extracts were concentrated to about 8 mL in vacuo and then stored for
three days at 258C. A dark red-violet microcrystalline solid precipitated
which was washed three times with 3 mL-portions of pentane ( 788C) and
1
ˆ ˆ
1875 (w) (CO and C C C) cm
;
13C{1H} NMR (100.6 MHz, C6D6): d ˆ
208.3 (t, J(P,C) ˆ 5.1 Hz, C C C), 195.6 (dt, 1J(Rh,C) ˆ 60.0, 2J(P,C) ˆ
3
ˆ ˆ
15.8 Hz, Rh CO), 104.3 (s, Rh C C C), 97.9 (dt, 1J(Rh,C) ˆ 25.4,
ˆ ˆ
2
ꢀ
J(P,C) ˆ 12.2 Hz, Rh C), 94.8, 92.0 (both s, C C), 26.0 (br.m, PCHCH3),
20.7, 20.1 (both br.m, PCHCH3).
dried; yield 260 mg (81%); m.p. 1288C (decomp); IR (nujol): nÄ ˆ 2059
1
(C C), 1869 (C C C) cm 1; H NMR (400 MHz, C6D6): d ˆ 3.01 (m, 6H,
Received: September 23, 1999 [Z14052]
ꢀ
ˆ ˆ
788
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0570-0833/00/3904-0788 $ 17.50+.50/0
Angew. Chem. Int. Ed. 2000, 39, No. 4

COMMUNICATIONS
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Dialkylaminoethyl-Functionalized ansa-
Zirconocene Dichlorides: Precatalysts for the
Regulation of the Molecular Weight
Distribution of Polyethylene**
[7] H. Kriegsmann, H. Geissler, Z. Anorg. Allg. Chem. 1963, 323, 170 ±
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Christian Müller, Dieter Lilge, Marc Oliver Kristen,*
and Peter Jutzi*
[8] a) M. Brady, W. Weng, Y. Zhou, J. B. Seyler, A. J. Amoroso, A. M.
Arif, M. Böhme, G. Frenking, J. A. Gladysz, J. Am. Chem. Soc. 1997,
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references therein.
Dedicated to Professor Reinhard Schmutzler
on the occasion of his 65th birthday
The synthesis of metallocene derivatives which can be used
as precatalysts in the methylalumoxane (MAO)-activated
polymerization of a-olefins is a rapidly growing research area.
Special attention is directed to the design of the metal
coordination sphere: variations in the substitution pattern and
in the connection of cyclopentadienyl (Cp) ligands may be
utilized for synthesizing tailor-made single-site catalysts. Thus,
polymer parameters such as stereochemical microstructure
(tacticity), molecular weight distribution, crystallinity, and
copolymer incorporation can be influenced systematically.[1, 2]
This new generation of catalysts therefore is playing an
important role in the development of new polyolefin-based
materials.
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The molecular weights of polymers produced with
[Cp2ZrCl2]/MAO catalysts range between 100000 and
1
1000000 gmol for polyethylenes and between 200 and
[13] Data for the X-ray structure analysis of 9: Crystals from acetone,
C41H61O2P2Rh (Mr ˆ 750.75); crystal size 0.20  0.20  0.15 mm3;
monoclinic, space group P21/c (no. 14), a ˆ 11.891(1), b ˆ 13.328(1),
1
1000 gmol
for polypropylenes. Polymers made by the
conventional Ziegler± Natta process have broad molecular
weight distributions with high polydipersities of Mw/Mn ˆ
5 ± 10, whereas single-site metallocene catalysts usually pro-
duce polyolefins with a unimodal molecular weight distribu-
tion and polydispersities of about 2. With respect to these
features, there are no differences between unbridged, bridged,
or Cp-substituted systems.[1a, 3]
c ˆ 25.797(3) Š, b ˆ 98.29(1)8, Z ˆ 4, Vˆ 4045.6(7) Š3, 1calcd
ˆ
1.233 gcm 3; Tˆ 173(2) K; 2Vˆ 54.208; 33008 reflections measured,
8328 were unique (Rint. ˆ 0.0696), and 4799 observed (I > 2s(I)); IPDS
(STOE), MoKa radiation (l ˆ 0.71073 Š), graphite monochromator;
Lp correction. The structure was solved by Patterson method
(SHELXS-97; G. M. Sheldrick, Acta Crystallogr. Sect. A 1990, 46,
467) and refined with the full-matrix, least-squares method
(SHELXL-97; G. M. Sheldrick,
a program for crystal structure
refinement, Universität Göttingen, 1993); R1 ˆ 0.0357, wR2 ˆ 0.0629
(for 4799 reflections with I > 2s(I)), R1 ˆ 0.0804, wR2 ˆ 0.0711 (for all
8328 data); data-to-parameter ratio 18.10; residual electron density
‡0.483/ 1.224 eŠ 3. One phenyl group consisting of the atoms C18
to C23 is disorded; two alternative positions were refined anisotropi-
cally with restraints on the anisotropic displacement parameters with
the occupancy factors 57.5% and 42.5%. Crystallographic data
(excluding structure factors) for the structures reported in this paper
have been deposited with the Cambridge Crystallographic Data
Centre as supplementary publication no. CCDC-134997. Copies of the
data can be obtained free of charge on application to CCDC, 12 Union
Road, Cambridge CB21EZ, UK (fax: (‡44)1223-336-033; e-mail:
deposit@ccdc.cam.ac.uk).
[*] Prof. Dr. P. Jutzi, Dipl.-Chem. C. Müller
Fakultät für Chemie der Universität
Universitätsstrasse 25, 33615 Bielefeld (Germany)
Fax: (‡49)521-106-6026
E-mail: peter.jutzi@uni-bielefeld.de
Dr. M. O. Kristen, Dr. D. Lilge
BASF Aktiengesellschaft, Kunststofflaboratorium
Forschung Polyolefine
67056 Ludwigshafen (Germany)
[**] Financial support provided by the Deutsche Forschungsgemeinschaft,
the Universität Bielefeld, and the Fonds der Chemischen Industrie is
gratefully acknowledged. We thank the Witco GmbH, Bergkamen,
Germany, for generous gifts of MAO and Prof. Dr. C. Janiak
(Universität Freiburg) for valuable technical advice.
[14] M. Schäfer, Dissertation, Universität Würzburg, 1994.
[15] H. Bibas, M. W. Wong, C. Wentrup, Chem. Eur. J. 1997, 3, 237 ± 248.
Angew. Chem. Int. Ed. 2000, 39, No. 4
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