Formation and structures of [1,2-bis(N-tert- butylcarbamoyl)cyclopentadienyl]zirconium complexes - Coordination chemistry of a 'fulvenologous' malonic amide anion ligand system

Article abstract of DOI:10.1002/(SICI)1099-0682(199901)1999:1<11::AID-EJIC11>3.0.CO;2-5

Treatment of sodium cyclopentadienide with two molar equivalents of tert-butyl isocyanate yields sodium 1,2-bis(N-tert- butylcarbamoyl)cyclopentadienide (6). The [C₅H₃(1,2-CONHCMe₃)₂]Na reagent 6 adds to Cp₂Zr(CH₃)Cl (8) to yield Cp₂Zr(CH₃)[C₅H₃(CONHCMe₃)₂] (9). In 9 the C₅H₃(CONHCMe₃)₂ ligand is bonded to zirconium through one of its carboxamido-oxygen atoms (κO-coordination). Treatment of 6 with CpZrCl₃(THF)₂ yields CpZrCl₂[C₅H₃(CONHCMe₃)₂](THF) 11. In 11 the 1,2- bis(N-tert-butylcarbamoyl)cyclopentadienide moiety serves as a C(s)-symmetric chelate ligand, binding to zirconium through both carbamoyl oxygens (κ²O,O'-coordination). The same seven-membered metallacyclic structural type is found in the reaction products of 6 with ZrCl₄(THF)₂ in 1:1 and 2:1 molar ratios. The former yields the distorted octahedral complex ZrCl₃[C₅H₃(CONHCMe₃)₂](THF) (12), the latter gives the chiral octahedral system ZrCl₂[C₅H₃(CONHCMe₃)₂]₂ (13). In solution, complex 13 undergoes a thermally induced enantiomerization process (Λ ? Δ interconversion), for which a Gibbs activation energy of ΔG(+/+)(enant) = 14.0 ± 0.3 kcal mol^{- 1} was determined by dynamic ¹H-NMR spectroscopy. The κ²O,O'-coordination of the [C₅H₃(1,2-CONHCMe₃]^- ligand in the complexes 11, 12, and 13 was secured by X-ray crystal structure analyses.

Full text of DOI:10.1002/(SICI)1099-0682(199901)1999:1<11::AID-EJIC11>3.0.CO;2-5

FULL PAPER
Formation and Structures of [1,2–Bis(N-tert-butylcarbamoyl)-
cyclopentadienyl]zirconium Complexes – Coordination Chemistry of
a “Fulvenologous” Malonic Amide Anion Ligand System
Katrin Klaß,[a] Lothar Duda,[a] Nina Kleigrewe,[a] Gerhard Erker,*[a] Roland Fröhlich,[a]
and Elina Wegelius[a]
Dedicated to Professor Bernt Krebs on the occasion of his 60th birthday
Keywords: Functionalized Cp ligand / κ2O,OЈ-Chelate / Carboxamido-substituted cyclopentadienides / Zirconium
complexes
Treatment of sodium cyclopentadienide with two molar
equivalents of tert-butyl isocyanate yields sodium 1,2-bis(N-
tert-butylcarbamoyl)cyclopentadienide (6). The [C5H3(1,2-
CONHCMe3)2]Na reagent 6 adds to Cp2Zr(CH3)Cl (8) to
membered metallacyclic structural type is found in the
reaction products of 6 with ZrCl4(THF)2 in 1:1 and 2:1 molar
ratios. The former yields the distorted octahedral complex
ZrCl3[C5H3(CONHCMe3)2](THF) (12), the latter gives the
chiral octahedral system ZrCl2[C5H3(CONHCMe3)2]2 (13). In
yield Cp2Zr(CH3)[C5H3(CONHCMe3)2] (9). In
9
the
C5H3(CONHCMe3)2 ligand is bonded to zirconium through
one of its carboxamido-oxygen atoms (κO-coordination).
Treatment of 6 with CpZrCl3(THF)2 yields CpZrCl2[C5H3-
(CONHCMe3)2](THF) 11. In 11 the 1,2-bis(N-tert-butyl-
solution, complex 13 undergoes
enantiomerization process (Λ v ∆ interconversion), for which
a Gibbs activation energy of ∆G‡ = 14.0 ± 0.3 kcal mol–1
was determined by dynamic 1H-NMR spectroscopy. The
κ2O,OЈ-coordination of the [C5H3(1,2-CONHCMe3]– ligand
in the complexes 11, 12, and 13 was secured by X-ray crystal
structure analyses.
a
thermally induced
enant
carbamoyl)cyclopentadienide moiety serves as
a
Cs-
symmetric chelate ligand, binding to zirconium through both
carbamoyl oxygens (κ2O,OЈ-coordination). The same seven-
We had previously shown that the cyclopentadienyl anion
rapidly adds to a variety of alkyl- and arylisocyanates.[5][6]
Subsequent to the carbon-carbon coupling step a rapid pro-
ton transfer takes place and the respective N-aryl- or N-
alkylcarboxamido-substituted cyclopentadienides were ob-
tained with moderate to good yields and selectivities.
Formally these systems constitute carbamoyl-substituted
cyclopentadienyl anion systems, but their fulvenoid meso-
meric resonance structures must probably be taken into ac-
count for their ample structural and electronic descrip-
tion.[7] Nevertheless, transmetallation of the [C5H4Ϫ
CONHRϪ]anion equivalents to e.g. titanium straight-
forwardly led to the selective formation of (η5-
C5H4ϪCONHR)[Ti] complexes, such as e.g. 4. Only coordi-
nation of the ligand system through the five cyclopen-
tadienyl ring carbon atoms was observed. The carboxamide
functional group did not participate in the bonding of this
ligand type to the central group 4 metal center. This was
unequivocally shown by an X-ray crystal structure analysis
of a representative example.[5]
Introduction
Compounds derived from mono- and especially from
bis(η-cyclopentadienyl) group 4 metal complexes have be-
come of enormous importance in organometallic chemistry
and catalysis.[1] Numerous variations at the Cp-ring systems
have been devised and carried out, many of those in the
development of improved homogeneous metallocene Zieg-
ler catalysts and related systems. Most of the variations in-
volved the attachment or anellation of hydrocarbyl moie-
ties.[2] Functional groups have much less frequently been
used for derivatising the Cp-rings, although there has been
a variety of group 4 metallocene examples bearing Cp-side
chains that contain amino-, phosphanyl-, or borane (and
borate) substituents.[3] However, the more reactive car-
bonyl-derived functional groups are still very rarely found
attached to Cp-type ring systems in group 4 metallocene
and related chemistry. Following the pioneering work by
M. D. Rausch et al.[4] we have searched for new ways of
introducing reactive carbonyl substituents, especially car-
boxamide-derived groups at Cp-ligands, and then to attach
them to the electropositive, oxophilic early transition met-
als.
This raises the question about the structural conse-
quences that arise from attaching more than one electron-
withdrawing carboxamido-substituent at the anionic Cp li-
gand. Especially in the case of two “ortho”-positioned car-
bonyl substituents,[8] that can cooperatively remove cyclo-
pentadienide electron density, a situation might arise where
the remaining Cp-nucleophilicity is not sufficient to warrant
binding of the carbocyclic ring system to an early transition
[a]
Organisch-Chemisches Institut der Universität Münster,
Corrensstr. 40, D-48149 Münster, Germany
Fax: (internat.) ϩ49 (0)251/ 83 36503
E-mail: erker@uni-muenster.de
Eur. J. Inorg. Chem. 1999, 11Ϫ19
WILEY-VCH Verlag GmbH, D-69451 Weinheim, 1999
1434Ϫ1948/99/0101Ϫ0011 $ 17.50ϩ.50/0
11

K. Klaß, L. Duda, N. Kleigrewe, G. Erker, R. Fröhlich, E. Wegelius
FULL PAPER
Hydrolysis of 6 gives the neutral system 7. The spectro-
scopic features (e.g. 1H NMR ϪOH signal at δ 19.7 in
CDCl3) indicate the presence of a fully enolized tautomer
with CϭO···HϪOϪ bridging hydrogen. Again, the ob-
tained product 7 exhibits NMR spectra that are consistent
with a fully delocalized C2v-symmetric species in solution.
It thus seems justified to consider the compound 7 (and the
anion 6 derived from it) as fulvene-expanded analogues of
the respective malonic amides. One might, therefore, term
such systems “fulvenologous” β-dicarbonyl compounds.
The compounds 7 and 6 may then be regarded as a fulveno-
logous malonic amide or malonic amide anion, respectively.
Scheme 1. Formation and metal coordination of the
[C5H4CONHR]Ϫ ligand
metal center. Then a situation is conceivable where a switch-
ing of the preferred coordination mode from η5-CpX2 to
potentially favored chelate bonding through the substituent
nitrogen or, more likely, oxygen atoms might occur. We have
prepared such a ligand system and attached it to a series of
organometallic zirconium containing frameworks of
decreasing overall electronic unsaturation to see which of
the possible coordination modes, η5-cyclopentadienyl or
bis(carboxamide) substituent κ2O,OЈ-chelate is favored.
Results and Discussion
The 1,2-biscarbamoyl-Cp ligand system employed in this
study was selectively prepared by treatment of sodium
cyclopentadienide with two molar equivalents of tert-butyl
isocyanate in tetrahydrofuran. The twofold addition took
Scheme 2. Preparation of a [C5H3(CONHR)2]Ϫ ligand
The anion 6 was then reacted with a variety of zirconium
place readily at temperatures between 0°C and room tem- complexes with a varying degree of coordinative unsatu-
perature. In view of our earlier work[5] it must be assumed ration and electrophilicity. We first treated the reagent 6
that the reaction sequence proceeds through the mono- with Cp2Zr(CH3)Cl (8).[9]
functionalized intermediates 2 and 3 (see Scheme 1, but in
Complex 8 reacts rapidly with 6 in a 1:1 molar ratio in
this case with the Naϩ counterion). Apparently, the anion toluene solution. The product 9 of the composition
3 still contains a sufficiently nucleophilic substituted cyclo- Cp2Zr(CH3)[C5H3(CONHCMe3)2] was isolated in ca. 60%
pentadienide ring system to allow for a rapid subsequent yield. The NMR spectra of 9 are in accord with a Cs-sym-
attack at the strongly electrophilic sp-hybridized carbon metric structure in solution. The complex contains a pair
atom of the tert-butyl isocyanate reagent present in the of symmetry-equivalent η5-cyclopentadienyl ligands (1H/
solution. Again, proton transfer seems to be rapid at the 13C NMR signals observed at δ 6.22/112.1) and a single
stage of the intermediate resulting from the addition reac- metal-bound CH3 group (δ 0.38/29.7 in CD2Cl2 solution).
tion (compound 5 in Scheme 2) to give the doubly carba- The C5H3(CONHCMe3)2 ligand is unsymmetrically coordi-
1
moyl substituted anionic ligand system 6. The twofold tert- nated to zirconium. It exhibits two sets of H- and 13C-
butyl isocyanate addition reaction sequence is strictly 1,2- NMR resonances of the ϪCONHCMe3 groups, five sepa-
selective. This is probably due to a pronounced anion-stabi- rated 13C-NMR resonances of the carbon atoms of the
lization in 6, as it is illustrated by the fulvenoid resonance C5H3 ring and an ABC-type 1H-NMR pattern for the C5H3
forms 6A/6AЈ (see Scheme 2).[8] Indeed, the NMR spectra hydrogen resonances (at 213 K, 150/600 MHz). This spec-
of 6 indicate a delocalized C2v-symmetric structure in solu- troscopic behavior is incompatible with the formation of a
1
tion. There is only one set of H/13C NMR signals for the complex containing an η5-C5H3X2 ligand in addition to a
pair of symmetry-equivalent ϪCONHCMe3 substituents pair of η5-C5H5 moieties. We must assume that the
(for details see the Experimental Section). Also, complex 6 C5H3(CONHCMe3)2 ligand in 9 is bonded to zirconium
exhibits an apparent AX2 1H-NMR spin pattern of the cen- through oxygen. We assume that complex 9 contains one
3
tral C5H3 unit (δ 6.73, d, 2 H; 6.25, t, 1 H; J ϭ 3.6 Hz; uncomplexed ϪCONHCMe3 substituent, i.e. that the
corresponding 13C NMR CH signals at δ 115.1 and 108.8). C5H3(CONHCMe3)2 ligand is only attached to the
12
Eur. J. Inorg. Chem. 1999, 11Ϫ19

[1,2ϪBis(N-tert-butyl-carbamoyl)cyclopentadienyl]zirconium Complexes
FULL PAPER
Cp2ZrCH3 unit through one of the carbonyl oxygen atoms [C5H3(CONHCMe3)2] ligand is bonded to the early tran-
(i.e. κ1O-coordination). This structural interpretation seems sition metal center only through its carboxamido-oxygen
˚
to be called for in view of the observation of two very differ- atoms (ZrϪO1: 2.093(3), ZrϪO2: 2.081(2)A). The ligand is
1
ent H-NMR chemical shifts of the respective NH amido part of a seven-membered metallacycle, that contains large
hydrogen atoms (at 213 K and 600 MHz in CD2Cl2 ob- bonding angles at the oxygen atoms[14] [C1ϪO1ϪZr:
served at δ 12.91 and 6.00, respectively). The IR spectrum 145.3(2)°, C2ϪO2ϪZr: 145.0(2)°] and a rather small σ-li-
is in accord with this interpretation: in this series of gand angle at zirconium (O1ϪZrϪO2: 82.7(1)°]. The anel-
[C5H3(CONHCMe3)2]zirconium complexes (see below) lated C5H3-ring system has no close contact to zirconium.
only complex 9 exhibits a band (at 1643 cmϪ1) that can be It is in principle oriented in the C4O2Zr seven-membered
attributed to a free uncoordinated carboxamido functional ring plane, but bent slightly in the direction toward the ad-
group.
jacent η5-cyclopentadienyl ring because of a boat-like dis-
Complex 9 shows dynamic NMR spectra. Raising the tortion of the seven-membered metallacycle from planari-
temperature from 213 K rapidly leads to coalescence of the ty.[14a] Because of this distortion the (η5-Cp)[κ2O,OЈ-
pairs of diastereotopic groups at the C5H3(CONHCMe3)3 C5H3(CONHCMe3)2]Cl2Zr moiety may be regarded as a
ligand. From the 1H NMR coalescence of the C(CH3)2 res- square-pyramidal subunit inside the overall octahedral co-
onances (200 MHz, Tc ϭ 289 K, ∆ν ϭ 22 Hz) a Gibbs ordination polyhedron around the central zirconium atom
activation energy of ∆G°
ϭ 14.9 ± 0.3 kcal molϪ1 (see Figure 1). A weakly bound tetrahydrofuran ligand
exchange
was determined.[10] We assume that a pentacoordinate [ZrϪO31 2.365(3)A] trans to the η -Cp group completes
Cp2Zr(CH3)[C5H3(CONHCMe3)2] structure (10) is likely to the ligand sphere around Zr in 11. Both the ZrϪO1/O2 and
be formed as an intermediate which has both carbonyl oxy- the ZrϪCl1/Cl2 bonds are bent toward this THF ligand
gen atoms coordinated at the available coordination sites at [angles O1ϪZrϪO31: 75.0(1)°, O2ϪZrϪO31: 75.2(1)°,
the front of the bent metallocene wedge.[11] Opening and Cl1ϪZrϪCp(centroid): 104.1°, Cl2ϪZrϪCp(centroid):
closing these bonds similarly as it has been shown to pro- 102.8°].
5
˚
ceed in η2 o η1 o η2-acyl group 4 metallocene isomeriza-
Inside the σ-bonded C5H3(CONHCMe3)2 ligand the
tions and related processes[12] probably provides an ample double bonds are fully delocalized. There seems to be a
mechanistic scheme for describing the automerization pro- pronounced difference in CϪC bond lengths with shorter
cess observed to take place in complex 9 (see Scheme 3).
values being favored at the distal end away from zirconium,
but this effect is equal for both ligand sides [e.g. C6ϪC5/
˚
C6ϪC7: 1.385(6), 1.387(3) A; C5ϪC4/C7ϪC3: 1.398(5)/
˚
˚
1.401(5) A; C3ϪC1/C4ϪC2: 1.445(3)/1.436(5) A; the length
˚
of the central conjugated C3ϪC4 bond is 1.440(5) A].
The CϪC(ϭO)ϪN(H)ϪC carboxamido groups are
trans-configurated. Therefore, the bulky tert-butyl substitu-
ents at the carbamoyl-nitrogen atoms are oriented toward
the chlorine atoms in the central O2Cl2Zr containing plane
of the complex 11. The corresponding bond angles at nitro-
gen are 128.8(4)° (C2ϪN2ϪC21) and 127.8(3)°
(C1ϪN1ϪC11), respectively.
Scheme 3. Formation and dynamic behavior of 9
We next reacted (η-cyclopentadienyl)zirconium trichlo-
ride[13] (as the bis-THF adduct) with the ligand system 6.
The chloride substitution reaction proceeds cleanly in a 1:1
The structure of 11 in solution seems to be similar. Com-
stoichiometry, and we have isolated the product 11 in >70% plex 11 shows static NMR spectra. The C5H3-
yield as a solid from the reaction mixture. Single crystals of (CONHCMe3)2 ligand is Cs-symmetrically bonded to zir-
1
11 suited for an X-ray crystal structure analysis were ob- conium. In CD2Cl2 solution the single H-NMR NH reso-
tained by letting pentane diffuse through the gas phase into nance occurs at δ 6.41 (br s, 2 H), and the C5H3 unit is
1
a toluene/dichloromethane solution of 11. Complex 11 can characterized by H-NMR resonances at δ 6.70 (d, 2 H)
3
be regarded as chemically Cs-symmetric, but not strictly so and 6.10 (t, 1 H, J ϭ 3.8 Hz). The observed carboxamide
crystallographically. The unsubstituted cyclopentadienyl li- IR features [ν˜ ϭ 3412 and 3322 cmϪ1 (NH), 1570 and 1529
gand is η5-coordinated to zirconium with ZrϪC(Cp) bond cmϪ1 (CONH)] also indicate O-coordination of the delo-
˚
lengths ranging from 2.490(5) to 2.555(4) A. The calized C5H3(CONHCMe3)2 ligand system to zirconium.
Eur. J. Inorg. Chem. 1999, 11Ϫ19
13

K. Klaß, L. Duda, N. Kleigrewe, G. Erker, R. Fröhlich, E. Wegelius
FULL PAPER
Figure 1. A view of the molecular structure of 11; selected bond
lengths and angles: ZrϪO1 2.092(3), ZrϪO2 2.081(2), O1ϪC1
1.280(4), O2ϪC2 1.291(4), C1ϪN1 1.322(5), C2ϪN2 1.325(5),
N1ϪC11 1.489(5), N2ϪC21 1.492(5), C1ϪC3 1.445(5), C2ϪC4
1.436(5), C3ϪC4 1.440(5), C3ϪC7 1.401(5), C4ϪC5 1.398(5),
C5ϪC6 1.385(6), C6ϪC7 1.387(5), ZrϪCl1 2.4892(11), ZrϪCl2
2.5067(10), ZrϪCp(centroid) 2.230, ZrϪO31 2.365(3); O1ϪZrϪO2
82.73(10), O1ϪZrϪO31 74.96(10), O2ϪZrϪO31 75.18(9),
O1ϪZrϪCl1 152.02(8), O1ϪZrϪCl2 86.07(7), O1ϪZrϪCp(cen-
troid) 103.8, O2ϪZrϪCl1 91.86(6), O2ϪZrϪCl2 168.54(6),
Coordination of this ligand takes place solely through the
ϪCONHCMe3 oxygen atoms. The carbon framework is
again fully delocalized and exhibits very similar bonding
features as already observed for the analogously structured
[C5H3(CONHCMe3)2]Zr unit in 11. The in-plane oriented
ϪCONHR groups again exhibit
a trans-configurated
O2ϪZrϪCp(centroid)
102.7,
O31ϪZrϪCl1
77.08(7),
O31ϪZrϪCl2 79.18(7), O31ϪZrϪCp(centroid) 177.6, Cl1ϪZrϪ
Cl2 89.93(4), Cl1ϪZrϪCp(centroid) 104.1, Cl2ϪZrϪCp(centroid)
102.8, ZrϪO1ϪC1 145.3(2), ZrϪO2ϪC2 145.0(2), O1ϪC1ϪN1
CϪC(ϭO)ϪN(H)ϪC(Me3) framework and consequently
have their bulky tert-butyl residues oriented towards the in-
plane ZrCl2 section. The coordination geometry around zir-
conium is almost ideally octahedral. The deviations of the
O3Cl3Zr octahedral core from the ideal expected geometry
are much smaller than e.g. observed for the O3Cl2(Cp)Zr
core in 11 (see above).
118.1(3),
O2ϪC2ϪN2
117.2(3),
O1ϪC1ϪC3
123.1(3),
O2ϪC2ϪC4 122.6(3), N1ϪC1ϪC3 118.8(3), N2ϪC2ϪC4
120.2(3), C1ϪN1ϪC11 127.8(3), C2ϪN2ϪC21 128.8(4),
C1ϪC3ϪC4 132.0(3), C2ϪC4ϪC3 129.3(3), C1ϪC3ϪC7 121.3(3),
C2ϪC4ϪC5 124.1(3), C4ϪC3ϪC7 106.6(3), C3ϪC4ϪC5 106.5(3),
C3ϪC7ϪC6 109.4(3), C4ϪC5ϪC6 109.7(4), C5ϪC6ϪC7 107.7(3)
In 12 the ZrϪO1 and ZrϪO2 bond lengths are 2.063(2)
[15a]
˚
We have then reacted 6 with zirconium tetrachloride. The and 2.036(2) A, respectively.
The ZrϪCl1/ϪCl2 bonds
˚
group 4 metal halide was introduced as its tetrahydrofuran are 2.426(1) and 2.448(1) A in length, whereas the perpen-
adduct (i.e. ZrCl4 ·2 THF), and the reaction was performed dicularly oriented ZrϪCl3 is shorter at 2.397(1) A.
[16]
˚
The
in toluene. The outcome was dependent on the chosen ratio coordinated THF molecule is located trans to it. The corre-
[15b]
˚
of the reagents and it relied somewhat on the reaction con- sponding ZrϪO31 bond length is 2.232(2) A.
This is
ditions. Employing the reagents 6 and ZrCl4 · 2 THF in a considerably shorter than observed for the THF coordi-
1:1 molar ratio and heating the mixture for ca. 1 d at 60°C nation in 11 as it is expected for a complex derived from
gave a precipitate (after cooling) from which the mono-sub- the more electrophilic LZrCl3 building block in comparison
stitution product 12 was obtained by extraction with di- to the LZrCl2(Cp) moiety. The very close to octahedral ar-
chloromethane (35% isolated). There was a small amount rangement of the core atoms of 12 around zirconium is il-
of the di-substitution product 13 recovered from the toluene lustrated by the close to linear arrangement of the
filtrate of this reaction. However, the complex 13 is easier O31ϪZrϪCl3 moiety [178.62(5)°]. Also the O1ϪZrϪCl1
prepared by treatment of 6 with ZrCl4 ·2 THF directly in a [170.03(6)°] and O2ϪZrϪCl2 [168.54(6)°] units are only
2:1 molar ratio in toluene at 60°C. In this case, the product slightly bent, and the deviation of the respective vectors
13 was obtained in >60% yield.
from orthogonality is also very small [e.g.: O1ϪZrϪCl2:
Complex 12 contains a coordinated THF molecule. Ac- 89.00(6)°, O2ϪZrϪCl1: 91.86(6)°, O2ϪZrϪCl3: 94.54(6),
cording to the NMR and IR spectra is exhibits very similar O1ϪZrϪCl3: 95.58(6)°]. The anellated C5H3 ring at the
bonding features of the [C5H3(CONHCMe3)2] ligand as C4O2Zr boat-shaped metallacyclic core of 12 is oriented to-
found in 11. The ligand is probably symmetrically coordi- ward the coordinated THF molecule. This is opposite of
1
nated through both oxygen atoms. The characteristic H- what is observed in the structurally and otherwise also con-
NMR NH resonance of 12 is observed at δ 6.55 (br s, 2 H), formationally related complex 11.
and the IR features typical for this ligand arrangement are
again observed (ν˜ ϭ 3419, 3347, 1577, 1535 cmϪ1).
Crystals of 13 were obtained by letting pentane diffuse
through the gasphase into a benzene/dichloromethane solu-
The κ2O,OЈ-coordination of the [C5H3(CONHCMe3)2] li- tion of the 2:1 reaction product. The X-ray crystal structure
gand of 12 was secured by the X-ray crystal structure analy- analysis of 13 shows that both [C5H3(CONHCMe3)2] li-
sis (see Figure 2). The (1,2-biscarbamoyl-Cp)Zr unit again gands in this complex are exclusively bonded to zirconium
forms a slightly boat-shaped seven-membered metallacycle. through their carbamoyl-oxygen atoms. Again the adjacent
14
Eur. J. Inorg. Chem. 1999, 11Ϫ19

[1,2ϪBis(N-tert-butyl-carbamoyl)cyclopentadienyl]zirconium Complexes
FULL PAPER
Figure 2. Molecular structure of 12; selected bond lengths and an-
gles: ZrϪO1 2.063(2), ZrϪO2 2.036(2), O1ϪC1 1.297(3), O2ϪC2
1.303(3), C1ϪN1 1.329(4), C2ϪN2 1.317(4), N1ϪC11 1.481(4),
N2ϪC21 1.485(3), C1ϪC3 1.429(4), C2ϪC4 1.424(4), C3ϪC4
1.446(4), C3ϪC7 1.410(4), C4ϪC5 1.403(4), C5ϪC6 1.393(4),
C6ϪC7 1.383(4), ZrϪCl1 2.4257(9), ZrϪCl2 2.4475(8), ZrϪCl3
2.3969(9), ZrϪO31 2.232(2); O1ϪZrϪO2 83.73(8), O1ϪZrϪO31
84.70(8), O2ϪZrϪO31 84.15(8), O1ϪZrϪCl1 170.03(6),
O1ϪZrϪCl2 89.00(6), O1ϪZrϪCl3 95.58(6), O2ϪZrϪCl1
91.86(6), O2ϪZrϪCl2 168.54(6), O2ϪZrϪCl3 94.54(6),
O31ϪZrϪCl1 85.96(6), O31ϪZrϪCl2 86.37(6), O31ϪZrϪCl3
178.62(5), Cl1ϪZrϪCl2 93.89(3), Cl1ϪZrϪCl3 93.68(4),
Cl2ϪZrϪCl3 94.98(3), ZrϪO1ϪC1 144.1(2), ZrϪO2ϪC2 146.7(2),
O1ϪC1ϪN1 117.4(3), O2ϪC2ϪN2 117.5(2), O1ϪC1ϪC3
Figure 3. A view of the molecular structure of complex 13; selected
˚
bond lengths [A] and angles [°]: ZrϪO1A 2.037(2), ZrϪO1B
2.045(2), ZrϪO2A 2.044(2), ZrϪO2B 2.050(2), O1AϪC1A
1.284(3), O1BϪC1B 1.277(3), O2AϪC2A 1.291(3), O2BϪC2B
1.284(3), C1AϪN1A 1.322(4), C1BϪN1B 1.325(4), C2AϪN2A
1.326(4), C2BϪN2B 1.336(3), N1AϪC11A 1.480(4), N1BϪC11B
1.488(4), N2AϪC21A 1.483(4), N2BϪC21B 1.478(4), C1AϪC3A
1.432(4), C1BϪC3B 1.429(4), C2AϪC4A 1.426(4), C2BϪC4B
1.430(4), C3AϪC4A 1.449(4), C3BϪC4B 1.454(4), C3AϪC7A
1.406(4), C3BϪC7B 1.398(4), C4AϪC5A 1.411(4), C4BϪC5B
1.402(4), C5AϪC6A 1.380(5), C5BϪC6B 1.382(4), C6AϪC7A
1.385(5), C6BϪC7B 1.386(5), ZrϪCl1 2.4489(9), ZrϪCl2
2.4435(8); O1AϪZrϪO2A 84.09(8), O1AϪZrϪO1B 86.79(9),
O1AϪZrϪO2B 91.18(8), O1AϪZrϪCl1 90.99(7), O1AϪZrϪCl2
173.41(6), O1BϪZrϪO2B 83.93(7), O1BϪZrϪO2A 91.75(8),
O1BϪZrϪCl1 174.66(6), O1BϪZrϪCl2 88.06(7), O2AϪZrϪO2B
173.77(8), O2AϪZrϪCl1 92.85(6), O2AϪZrϪCl2 91.97(6),
O2BϪZrϪCl1 91.27(6), O2BϪZrϪCl2 92.36(6), Cl1ϪZrϪCl2
94.49(4), ZrϪO1AϪC1A 152.08(2), ZrϪO1BϪC1B 152.4(2),
ZrϪO2AϪC2A 150.9(2), ZrϪO2BϪC2B 149.2(2), O1AϪ
C1AϪN1A 117.1(3), O1BϪC1BϪN1B 117.4(3), O2AϪ
C2AϪN2A 117.0(3), O2BϪC2BϪN2B 116.8(3), O1AϪC1AϪC3A
122.6(3), O1BϪC1BϪC3B 123.5(2), O2AϪC2AϪC4A 123.6(3),
O2BϪC2BϪC4B 124.8(2), N1AϪC1AϪC3A 120.3(3), N1BϪ
C1BϪC3B 119.1(23), N2AϪC2AϪC4A 119.4(3), N2BϪC2BϪ
C4B 118.3(3), C1AϪN1AϪC11A 128.1(32), C1BϪN1BϪC11B
128.4(3), C2AϪN2AϪC21A 129.5(3), C2BϪN2BϪC21B 129.3(3),
C1AϪC3AϪC4A 131.6(3), C1BϪC3BϪC4B 130.2(3), C2AϪ
C4AϪC3A 131.1(3), C2BϪC4BϪC3B 131.0(3), C1AϪC3AϪC7A
121.9(3), C1BϪC3BϪC7B 123.7(3), C2AϪC4AϪC5A 122.6(3),
C2BϪC4BϪC5B 122.7(3), C4AϪC3AϪC7A 106.5(3), C4BϪ
C3BϪC7B 106.9(3), C3AϪC4AϪC5A 106.3(3), C3BϪC4BϪC5B
106.3(2), C3AϪC7AϪC6A 109.3(3), C3BϪC7BϪC6B 110.2(3),
C4AϪC5AϪC6A 109.4(3), C4BϪC5BϪC6B 109.9(3), C5AϪ
C6AϪC7A 108.5(3), C5BϪC6BϪC7B 107.6(3).
123.2(3),
O2ϪC2ϪC4
122.4(3),
N1ϪC1ϪC3
119.4(2),
N2ϪC2ϪC4 120.0(2), C1ϪN1ϪC11 129.3(2), C2ϪN2ϪC21
128.2(2), C1ϪC3ϪC4 130.2(3), C2ϪC4ϪC3 131.0(3), C1ϪC3ϪC7
122.9(3), C2ϪC4ϪC5 122.5(3), C4ϪC3ϪC7 105.8(3) C3ϪC4ϪC5
106.5(2),
C3ϪC7ϪC6
109.0(3),
C4ϪC5ϪC6
109.3(3),
C5ϪC6ϪC7 108.4(3).
cyclopentadienide moiety is not involved in the bonding.
Chelate coordination of both ligands leads to the occur-
rence of two organometallic seven-membered ring systems.
Their overall bonding characteristics are very similar as has
already been observed for 11 and 12 (see above). The ob-
served bond lengths (for details see the legend of Figure 3)
indicate
a
complete π-delocalization at both the
C5H3CO(N) frameworks with individual characteristics of
bond lengths and angles that have been already discussed
for the related complexes 11 and 12.
The coordination polyhedron in 13 around the central
zirconium atom is close to ideally octahedral. The respec-
tive OϪZrϪO, OϪZrϪCl, and ClϪZrϪCl angles do not
deviate much from the expected values of 90° or 180°,
respectively (see Figure 3). In the solid state the cis-chelate
ligands are arranged close to C2-symmetric to give a chiral of symmetry-equivalent [C5H3(CONHCMe3)2] ligands
octahedral geometry of 13 (i.e. a racemate of the respective whose “right and left sides” are diastereotopic due to the
Λ and ∆ enantiomers).
chiral octahedral molecular geometry.[17] This leads to an
1
Complex 13 shows the expected characteristic IR features observation of an AMX-type H-NMR spin pattern of the
in KBr (ν˜ ϭ 3412, 3361 (NH), 1585, 1529 (delocalized am- C5H3 protons (signals at δ 6.64, 6.59, and 5.98 with coup-
ide)). The latter bands are almost unchanged when the IR ling constants 3J ϭ 4.2 Hz and J ϭ 1.8 Hz). There are two
4
spectrum is monitored in CDCl3 solution (1585, 1531 NH resonances at δ 6.61 and 6.42 and two separate signals
cmϪ1). This indicates that the solution structure of 13 is of the tert-butyl CH3 groups (δ 1.52 and 1.18). The 13C-
very similar to that observed in the solid state.
NMR spectrum shows the analogous diastereotopic split-
The NMR spectra indicate that the complex ting of the ϪCONH, C5H3Ϫ, and C(CH3)3 resonances (for
[C5H3(CONHCMe3)2]2ZrCl2 13 also attains a chiral C2- details see the Experimental Section).
1
symmetric octahedral structure in solution. The H-NMR
With increasing temperature the NMR signals of the re-
spectrum at 213 K in CD2Cl2 exhibits the signals of a pair spective pairs of diastereotopic groups broaden and eventu-
Eur. J. Inorg. Chem. 1999, 11Ϫ19
15

K. Klaß, L. Duda, N. Kleigrewe, G. Erker, R. Fröhlich, E. Wegelius
FULL PAPER
(AϪA)2ZrX2.[18] In view of the coordination properties ob-
served in this study of the complex [C5H3(CONHCMe3)2]-
Cp2ZrCH3 (9, see above), and of the properties of the litera-
ture systems,[18] it is likely that the Λ o ∆-isomerization of
13 is initiated by cleavage of one of the ZrϪO linkages to
generate a coordinatively unsaturated intermediate of a
higher molecular symmetry.
Conclusions
The reaction of cyclopentadienide with two molar equiv-
alents of the alkylisocyanate very selectively leads to the
formation of the 1,2-biscarbamoyl substituted cyclopen-
tadienide ligand system. Attachment of this ligand to a va-
riety of zirconium centered frameworks has in most cases
investigated in this study led to the formation of κ2O,OЈ-
bonded chelate zirconium complexes. In no case was the
attached C5H3-cyclopentadienide residue involved directly
in the bonding of the [C5H3(CONHCMe3)2] ligand system
to the oxophilic early transition metal. In contrast, we and
others had previously observed that the attachment of one
ϪCOX substituent at a Cp ring does not inhibit its η5-
C5H4ϪCOX attachment to a group 4 metal.[4][5] It may be
that we here have crossed a borderline, being encountered
when a second electron-withdrawing ϪCOX substituent,
suitably located at the Cp framework, removes too much
additional electron density from the ligand core, beyond
which the coordinative ability of the chelate system exceeds
that of the normal η5-Cp arrangement. It appears that 1,2-
COXϪ (or similarly) substituted cyclopentadienides may be
regarded as π-anellated cyclic vinylogues of the ubiquitous
β-diketonates and systems derived thereof. Related bis(imi-
no)C5H3 ligands have just recently been found to show a
complexation behavior[19] analogous to our bis(carba-
moyl)C5H3 systems 6, forming seven-membered chelate
complex systems. Also, a variety of troponolato chelate
complexes have recently been described.[20] Their ligand
systems may be regarded as structural isomers of the
Figure 4. A projection of the octahedral core of complex 13
Ϫ
Ϫ
C5H3(COX)2 or C5H3[CR(ϭNRЈ)]2 frameworks. Open-
ing viable synthetic pathways to novel chelate systems such
as those described here and in the related recent studies
could be of interest in view of the actual development and
the search for new homogeneous non-metallocene group 4
metal derived Ziegler systems.[21] The catalytic properties of
complexes derived from [C5H3(CONHR)2]Ϫ ligand systems
are currently investigated in our laboratory.
Scheme 4. Formation and enantiomerization of 13
ally undergo coalescence to give a much simplified appear-
ance of the limiting NMR spectra at high temperature. This
observation indicates a rather rapid racemization of 13, i.e.
the thermally induced interconversion of the octahedral Λ
o ∆ configurated enantiomers of 13 in solution. From the
1H-NMR coalescence of the NH resonances of 13 an en-
Experimental Section
General Information: All reactions with organometallic reagents or
substrates were carried out under argon using Schlenk-type glass-
ware or in a glove-box. Solvents (including the deuterated solvents
used for NMR spectroscopy) were dried and distilled under argon
prior to use. Ϫ The following instruments were used for spectro-
scopic and physical characterization of the compounds: Bruker AC
200P (1H: 200.13, 13C: 50.3 MHz), Bruker ARX 300, and Varian
Unity Plus (1H: 599.2, 13C: 150.8 MHz) NMR spectrometers (spec-
antiomerization barrier of ∆G°
(298 K) ϭ 14.0 ± 0.3
enant
kcal molϪ1 was determined at the coalescence temperature.
Similar enantiomerization processes have previously been
observed for a variety of chiral octahedral bis-chelate ligand
zirconium complexes of the general types (AϪB)2ZrX2 or tral assignments were usually secured by GCOSY, GHSQC, and
16 Eur. J. Inorg. Chem. 1999, 11Ϫ19

[1,2ϪBis(N-tert-butyl-carbamoyl)cyclopentadienyl]zirconium Complexes
FULL PAPER
GHMBC experiments[22]); Nicolet 5 DXC FT-IR spectrometer; [1,2-Bis(N-tert-butylcarbamoyl)cyclopentadienyl](η5-cyclopenta-
melting points: DSC 2010 (Texas Instruments); elemental analyses: dienyl)dichlorozirconium (11): CpZrCl3 и 2 THF (5.77 g, 14.0 mmol)
Foss Heraeus CHN-Rapid; X-ray crystal structure analyses: Data
sets were collected with Enraf Nonius CAD4 and MACH3 dif-
fractometers, connected to sealed tube or rotating anode gener-
ators. Programs used: data reduction MolEN, structure solution
SHELXS-86, structure refinement SHELXL-93 and SHELXL-97,
graphics SCHAKAL-92. Crystallographic data (excluding struc-
ture factors) for the structures reported in this paper have been
deposited with the Cambridge Crystallographic Data Centre as
supplementary publication no. CCDC-102777Ϫ102779. Copies of
the data can be obtained free of charge on application to The Di-
rector, CCDC, 12 Union Road, CambridgeCB2 1EZ, UK
[Fax: int. code ϩ44 (1223) 336-033, E-mail: deposit@ccdc.cam.ac.uk].
was treated with [1,2-bis(N-tert-butylcarbamoyl)cyclopentadienyl]-
sodium (6) (4.06 g, 14.0 mmol) in 50 mL of tetrahydrofuran at
Ϫ78°C. The reaction mixture was stirred and allowed to warm to
room temperature overnight. It was filtered and the solvent was
removed in vacuo to give the product 11 as a pale yellow powder
in 74% yield (5.80 g), m.p. 180°C (DSC). Ϫ IR (KBr): ν˜ ϭ 3412
cmϪ1, 3322 (NH), 1570, 1529 (CONH) (in CDCl3 solution: 1576,
1525). Ϫ 1H NMR (CD2Cl2): δ ϭ 6.70 (d, 3J ϭ 3.8 Hz, 2 H, C5H3),
6.41 (br s, 2 H, NH), 6.38 (s, 5 H, C5H5), 6.10 (t, 3J ϭ 3.8 Hz, 1
H, C5H3), 4.00, 1.80 (m, each 4 H, THF), 1.46 (s, 18 H, CMe3). Ϫ
13C NMR (CD2Cl2): δ ϭ 169.7 (CONH), 121.4, 114.3 (CH of
C5H3), 117.7 (CH of C5H5), 113.9 (ipso-C of C5H3), 71.1 (CH2 of
THF), 53.3, 29.3 (CMe3), 25.5 (CH2 of THF). Ϫ C24H36Cl2N2O3Zr
(562.7): calcd. C 51.23, H 6.45, N 4.98; found: C 51.06, H 6.61,
N 5.09.
The reagents CpZrCl3(THF)2[13,15a] and Cp2Zr(CH3)Cl[9] were pre-
pared according to literature procedures.
[1,2-Bis(N-tert-butylcarbamoyl)cyclopentadienyl]sodium (6): A solu-
tion of 12.8 g (129.0 mmol, 15.2 mL) of tert-butyl isocyanate in 30
mL of tetrahydrofuran was added dropwise at 0°C to a solution of
5.1 g (58.0 mmol) of CpNa in 80 mL of tetrahydrofuran. The dark
yellow colored reaction mixture was allowed to warm to room tem-
perature overnight. Solvent was then removed in vacuo, and the
solid residue was washed once with pentane to give the product 6
as a pale yellow solid, m. p. 178°C (DSC). Ϫ IR (KBr): ν˜ ϭ 3442
X-ray crystal structure analysis of 11: Formula C24H36Cl2N2O3Zr,
M ϭ 562.7, colorless crystal, 0.40 ϫ 0.25 ϫ 0.10 mm, a ϭ
˚
10.725(1), b ϭ 17.410(2), c ϭ 14.699(2) A, β ϭ 100.25(1)°, V ϭ
3
2700.8(5) A , ρcalc ϭ 1.384 g cmϪ3, F(000) ϭ 1168 e, µ ϭ 6.31
˚
cmϪ1, empirical absorption correction via φ scan data (0.937 Յ C
Յ 0.999), Z ϭ 4, monoclinic, space group P21/n (No. 14), λ ϭ
˚
0.71073 A, T ϭ 223 K, ω/2θ scans, 5789 reflections collected (-h,
ϩk, ±l), [(sinθ)/λ] ϭ 0.62 AϪ1, 5493 independent and 3744 ob-
˚
1
cmϪ1, 3380 (NH), 1603, 1505 (CONH). Ϫ H NMR ([D6]benzene/
served reflections [I Ն 2 σ(I)], 301 refined parameters, R ϭ 0.047,
3
[D8]THF, 10:1.5): δ ϭ 7.90 ( br s, 2 H, NH), 6.73 (d, J ϭ 3.6 Hz,
Ϫ3
wR2 ϭ 0.108, max. residual electron density 0.69 (-0.74) e A
,
˚
3
2 H), 6.25 (t, J ϭ 3.6 Hz, 1 H, C5H3), 1.44 (s , 18 H, CMe3). Ϫ
hydrogens calculated and refined as riding atoms.
13C NMR ([D6]benzene/[D8]THF, 10:1.5): δ ϭ 170.7 (CONH),
116.4 (ipso-C, Cp), 115.1, 108.8 (CH of Cp), 50.3 and 29.6 (CMe3).
[1,2-Bis(N-tert-butylcarbamoyl)cyclopentadienyl]trichlorozirconium
Ϫ C15H23N2NaO2 (286.4): calcd. C 62.92, H 8.10, N 9.78; found: (12): [1,2-Bis(N-tert-butylcarbamoyl)cyclopentadienyl]sodium (6)
C 62.53, H 8.42, N 9.12.
(2.80 g, 9.8 mmol) was treated with ZrCl4 и 2 THF (3.70 g, 9.8
mmol) in 100 mL of toluene for 20 h at 60°C. The reaction mixture
was filtered and the residue was extracted with dichloromethane to
give 1.8 g (35%) of 12 as a pale yellow solid (from the toluene layer
the disubstituted compound 13 was obtained as a side product).
12: m.p. 243°C (DSC). Ϫ IR (KBr): ν˜ ϭ 3419 cmϪ1, 3347 (NH),
1,2-Bis(N-tert-butylcarbamoyl)cyclopentadiene (7): Water (50 mL)
and acetic acid (1 mL) was added to an ethereal solution (50 mL)
of 304 mg (1.06 mmol) of 6 at ambient temperature. The mixture
was vigorously stirred and then the organic phase was separated.
The aqueous phase was extracted with ether (2ϫ 20 mL). The com-
bined organic solutions were dried, solvent was removed in vacuo
and the residue chromatographed at silicagel to give 95 mg (34%)
1
1577, 1535 (CONH) (in CDCl3 solution: 1575, 1530). Ϫ H NMR
(CD2Cl2): δ ϭ 6.69 (d, 3J ϭ 3.9 Hz, 2 H, C5H3), 6.55 (br s, 2 H,
NH), 6.07 (t, 3J ϭ 3.9 Hz, 1 H, C5H3), 4.16, 1.76 (m, each 4 H,
THF), 1.54 (s, 18 H, CMe3). Ϫ 13C NMR (CD2Cl2): δ ϭ 168.7
(CONH), 123.0, 115.3 (CH of C5H3), 113.1 (ipso-C of C5H3), 75.5
1
of 7, which was only spectroscopically characterized. Ϫ H NMR
(200 MHz, CDCl3): δ ϭ 19.66 (br s, 1 H, OH), 6.53 (d, 3J ϭ 3.9
3
Hz, 2 H, C5H3), 6.11 (t, J ϭ 3.9 Hz, 1 H, C5H3), 6.09 (br s, 2 H,
(CH2 of THF), 54.3, 29.4 (CMe3) 25.7 (CH2 of THF).
Ϫ
NH), 1.46 (s, 18 H, CMe3). Ϫ 13C NMR (50 MHz, CDCl3): δ ϭ
168.2 (CϭO), 117.0, 113.6 (CH of C5H3), 112.3 (ipso-C of C5H3),
52.4 and 29.1 (tert-butyl).
C19H31N2O3Cl3Zr (533.0): calcd. C 42.81, H 5.86, N 5.26; found:
C 42.70, H 6.50, N 5.42.
X-ray Crystal Structure Analysis of 12: Formula C19H31N2O3Cl3Zr,
M ϭ 533.0, yellow crystal, 0.25 ϫ 0.15 ϫ 0.10 mm, a ϭ 9.805(2),
[1,2-Bis(N-tert-butylcarbamoyl)cyclopentadienyl]bis(η5-cyclopenta-
dienyl)methylzirconium (9): Chlorobis(η5-cyclopentadienyl)methyl-
zirconium (8) (500 mg, 1.8 mmol) was treated with [1,2-bis(N-tert-
butylcarbamoyl)cyclopentadienyl]sodium (6) (530 mg, 1.8 mmol) at
Ϫ78°C in 40 mL of toluene. The yellow colored mixture was stirred
overnight and allowed to warm to room temperature. Filtration
and solvent removal gives the yellow solid 9 in 60% yield (530 mg),
m.p. 98°C (DSC). Ϫ IR (KBr): ν˜ ϭ 3443 cmϪ1, 3091 (NH), 1643,
1586 (CONH) (in CDCl3 solution: 1648, 1580). Ϫ 1H NMR (599.9
3
˚
˚
b ϭ 15.932(4), c ϭ 16.082(3) A, β ϭ 105.37(2)°, V ϭ 2422.4(9) A ,
ρcalc ϭ 1.462 g cmϪ3, F(000) ϭ 1096 e, µ ϭ 8.06 cmϪ1, empirical
absorption correction via φ scan data (0.955 Յ C Յ 0.999), Z ϭ
˚
4, monoclinic, space group P21/n (No. 14), λ ϭ 0.71073 A, T ϭ
223 K, ω/2θ scans, 5214 reflections collected (ϩh, ϩk, ±l), [(sinθ)/
λ] ϭ 0.62 AϪ1, 4923 independent and 3550 observed reflections [I
˚
Ն 2 σ(I)], 265 refined parameters, R ϭ 0.032, wR2 ϭ 0.072, max.
residual electron density 0.51 (Ϫ0.57) e AϪ3, hydrogens calculated
˚
3
MHz, CD2Cl2, 213 K): δ ϭ 12.91 (br s, 1 H, NH), 6.44 (dd, J ϭ
and refined as riding atoms.
3.6 Hz, 4J ϭ 1.8 Hz, 1 H), 6.22 (s, 10 H, Cp), 6.03 (dd, 3J ϭ 3.6
4
3
Hz, J ϭ 1.8 Hz, 1 H), 6.00 (br s, 1 H, NH), 5.93 (t, J ϭ 3.6 Hz,
Bis[1,2-bis(N-tert-butylcarbamoyl)cyclopentadienyl]dichlorozir-
conium (13): A reaction mixture of [1,2-bis(N-tert-butylcarbamoyl)-
Me). Ϫ 13C NMR (150.8 MHz, CD2Cl2, 213 K): δ ϭ 168.6 cyclopentadienyl]sodium (6, 758 mg, 2.7 mmol) and ZrCl4 · 2 THF
1 H, C5H3), 1.33 (s, 9 H, CMe3), 1.23 (s, 9 H, CMe3), 0.38 (s, 3 H,
(CONH), 168.4 (CONH), 119.1, 117.5 (CH of C5H3), 112.1 (CH
of C5H5), 110.6, 110.7 (ipso-C of C5H3), 109.7 (CH of C5H3), 51.1,
50.4 (CMe3), 29.7 (Me), 28.5, 28.3 (CMe3). Ϫ C26H36N2O2Zr
(499.8): calcd. C 62.48, H 7.26; found: C 62.38, H 7.29.
(500 mg, 1.3 mmol) in 50 mL of toluene was stirred for 14 h at
60°C and then filtered. Solvent was removed in vacuo to yield 600
mg (65%) of 13 as a yellow solid, m.p. 269°C (DSC). Ϫ IR (KBr):
ν˜ ϭ 3412 cmϪ1, 3361 (NH), 1585, 1529 (CONH) (in CDCl3 solu-
Eur. J. Inorg. Chem. 1999, 11Ϫ19
17

K. Klaß, L. Duda, N. Kleigrewe, G. Erker, R. Fröhlich, E. Wegelius
FULL PAPER
3
tion: 1585, 1531). Ϫ 1H NMR ([D6]benzene): δ ϭ 6.43 (d, J ϭ 3.8
W. Tikkanen, J. W. Ziller, Organometallics 1991, 10, 2266; M.
Ogasa, M. D. Rausch, R. D. Rogers, J. Organomet. Chem. 1991,
405, 279; W. Tikkanen, A. L. Kim, K. B. Lam, K. Ruekert,
Organometallics 1995, 14, 1525. See also: B. E. Bosch, G. Erker,
R. Fröhlich, O. Meyer, Organometallics 1997, 16, 5449; B.
Bosch, G. Erker, R. Fröhlich, Inorg. Chim. Acta 1998, 270, 446.
3
Hz, 4 H, C5H3), 6.36 (t, J ϭ 3.8 Hz, 2 H, C5H3), 6.00 (br s, 4 H,
NH), 1.25 (br, 36 H, CMe3). Ϫ 13C NMR ([D6]benzene): δ ϭ 168.9
(CONH), 122.7 (CH of C5H3), 114.4 (ipso-C of C5H3), 114.0 (CH
of C5H3), 53.1, 29.1 (CMe3). Ϫ C30H46N4O4Cl2Zr · 1/3 C7H8
(715.9): calcd. C 53.69, H 6.90, N 7.83; found: C 53.60, H 7.28,
N 7.43.
Ϫ
[3c] M. T. Reetz, H. Brümmer, M. Kessler, J. Kuhnigk, Chimia
1995, 49, 501; S. A. Larkin, J. T. Golden, P. J. Shapiro, G. P. A.
Yap, D. M. J. Foo, A. L. Rheingold, Organometallics 1996, 15,
2393; D. S. Stelck, P. J. Shapiro, N. Basickes, A. L. Rheingold,
Organometallics 1997, 16, 4546; R. Duchateau, S. J. Lancaster,
M. Thornton-Pett, M. Bochmann, Organometallics 1997, 16,
4995; R. E. v. H. Spence, W. E. Piers, Organometallics 1995, 14,
4617; Y. Sun, R. E. v. H. Spence, W. E. Piers, M. Parvez, G. P.
A. Yap, J. Am. Chem. Soc. 1997, 119, 5132; W. E. Piers, Chem.
Eur. J. 1998, 4, 13. Ϫ [3d] J. Ruwwe, G. Erker, R. Fröhlich, An-
gew. Chem. 1996, 108, 108, Angew. Chem. Int. Ed. Engl. 1996,
35, 80; M. Bochmann, S. J. Lancaster, O. B. Robinson, J. Chem.
Soc., Chem. Commun. 1995, 2081; F. A. Shafig, K. A. Abboud,
D. E. Richardson, J. M. Boncella, Organometallics 1998, 17,
982; H. van der Heijden, B. Hessen, A. G. Orpen, J. Am. Chem.
Soc. 1998, 120, 1112; X. Song, M. Bochmann, J. Organomet.
Chem. 1997, 545/546, 597.
X-ray
Crystal
Structure
Analysis
of
13:
Formula
C30H46N4O4Cl2Zr ·C6H6, M ϭ 766.9, yellow crystal, 0.25 ϫ 0.20
˚
ϫ 0.10 mm, a ϭ 13.058(2), b ϭ 12.735(3), c ϭ 24.172(3) A, β ϭ
96.43(1)°, V ϭ 3994.4(12) A , ρcalc ϭ 1.275 g cmϪ3, F(000) ϭ 1608
3
˚
e, µ ϭ 4.49 cmϪ1, empirical absorption correction via φ scan data
(0.981 Յ C Յ 0.999), Z ϭ 4, monoclinic, space group P21/n (No.
˚
14), λ ϭ 0.71073 A, T ϭ 223 K, ω/2 θ scans, 8282 reflections col-
lected (±h, Ϫk, Ϫl), [(sinθ)/λ] ϭ 0.62 AϪ1, 8090 independent and
5503 observed reflections [I Ն 2 σ(I)], 448 refined parameters, R ϭ
0.037, wR2 ϭ 0.085, max. residual electron density 0.40 (Ϫ0.32) e
˚
˚
A
Ϫ3, hydrogens calculated and refined as riding atoms.
[4] [4a]
D. W. Macomber, W. P. Hart, M. D. Rausch, Adv. Or-
ganomet. Chem. 1982, 21, 1; N. J. Coville, W. Pickl, Coord.
Chem. Rev. 1992, 116, 1, and references cited in these articles.
[4b]
Acknowledgments
Ϫ
W. P. Hart, D. W. Macomber, M. D. Rausch, J. Am.
Chem. Soc. 1980, 102, 1196; W. P. Hart, D. Shihua, M. D.
Rausch, J. Organomet. Chem. 1985, 282, 111; M. D. Rausch, J.
F. Lewison, W. P. Hart, J. Organomet. Chem. 1988, 358, 161; S.
S. Jones, M. D. Rausch, T. E. Bitterwolf, J. Organomet. Chem.
1990, 396, 279; M. Ogasa, D. T. Mallin, D. W. Macomber, M.
D. Rausch, R. D. Rogers, A. N. Rollins, J. Organomet. Chem.
1991, 405, 41; S. S. Jones, M. D. Rausch, T. E. Bitterwolf, J.
Organomet. Chem. 1993, 450, 27.
M. Oberhoff, L. Duda, J. Karl, R. Mohr, G. Erker, R. Fröhlich,
M. Grehl, Organometallics 1996, 15, 4005.
F. Effenberger, R. Gleiter, L. Heider, R. Niess, Chem. Ber. 1968,
101, 502.
6-Aminofulvenes can be regarded electronically as carboxamide
analogues: K. Hafner, K. H. Vöpel, G. Ploss, C. König, Org.
Synth. 1967, 47, 52, and references cited therein.
See for a comparison: W. J. Linn, W. H. Sharkey, J. Am. Chem.
Soc. 1957, 79, 4970. D. Peters, J. Chem Soc. 1959, 1757; L. M.
Jackman, J. C. Trewella, R. C. Haddon, J. Am. Chem. Soc.
1980, 102, 2519; K. Hartke, A. Kohl, T. Kämpchen, Chem. Ber.
1983, 116, 2653; M. I. Bruce, J. K. Walton, M. L. Williams, S.
R. Hall, B. W. Skelton, A. H. White, J. Chem. Soc. Dalton
Trans. 1982, 2209; 1983, 2183; M. I. Bruce, P. A. Humphrey, J.
M. Patrick, B. W. Skelton, A. H. White, M. L. Williams, Aust.
J. Chem. 1985, 38, 1441; M. I. Bruce, P. A. Humphrey, B. W.
Skelton, A. H. White, J. Organomet. Chem. 1989, 361, 369; L.
B. Kool, G. J. Kotora, Macromolecules, 1992, 25, 2582, and ref-
erences cited in these articles.
J. R. Surtress, J. Chem. Soc., Chem. Commun.1965, 567.
M. L. H. Green, L.-L. Wong, A. Seela, A. Organometallics
1992, 11, 2660, and references cited therein.
H.-H. Brintzinger, L. S. Bartell, J. Am. Chem. Soc. 1970, 92,
1105; W. Lauher, R. Hoffmann, J. Am. Chem. Soc. 1976, 98,
1729.
Financial support from the Fonds der Chemischen Industrie, the
Deutsche Forschungsgemeinschaft, and the Ministerium für Schule
und Weiterbildung, Wissenschaft und Forschung des Landes
Nordrhein-Westfalen is gratefully acknowledged. E. W. thanks the
Academy of Finland for financial support.
[5]
[6]
[7]
[1]
G. Erker, Angew. Chem. 1989, 101, 411, Angew. Chem. Int. Ed.
Engl. 1989, 28, 397; H.-H. Brintzinger, D. Fischer, R.
Mülhaupt, B. Rieger, R. Waymouth, Angew. Chem. 1995, 107,
1255; Angew. Chem. Int. Ed. Engl. 1995, 34, 1143; C. A. Wil-
loughby, S. L. Buchwald, J. Am. Chem. Soc. 1994, 116, 8952,
11703; A. H. Hoveyda, J. P. Morken, Angew. Chem. 1996, 108,
1378; Angew. Chem. Int. Ed. Engl. 1996, 35, 1262; D. Y. Kon-
dakov, E. Negishi, J. Am. Chem. Soc. 1996, 118, 1577; J. Chris-
toffers, R. G. Bergman, J. Am. Chem. Soc. 1996, 118, 4715; S.
Thiele, G. Erker, Chem. Ber. 1997, 130, 201; D. Röttger, G.
Erker, Angew. Chem. 1997, 109, 840; Angew. Chem. Int. Ed.
Engl. 1997, 36, 812.
[8]
[2]
W. Kaminsky, K. Külper, H.-H. Brintzinger, F. R. W. P. Wild,
Angew. Chem. 1985, 97, 507; Angew. Chem. Int. Ed. Engl. 1985,
24, 507; J. A. Ewen, L. A. Jones, A. Razavi, J. D. Ferrara, J.
Am. Chem. Soc. 1988, 110, 6255; W. Spaleck, M. Antberg, J.
Rohrmann, A. Winter, B. Bachmann, P. Kiprof, J. Behm, W. A.
Herrmann, Angew. Chem. 1992, 104, 1373; Angew. Chem. Int.
Ed. Engl. 1992, 31, 1347; G. Erker, M. Aulbach, M. Knickmeier,
D. Wingbermühle, C. Krüger, M. Nolte, S. Werner, J. Am.
Chem. Soc. 1993, 115, 4590; M. Aulbach, F. Küber, Chemie
Unserer Zeit 1994, 28, 197; M. Knickmeier, G. Erker, T. Fox, J.
Am. Chem. Soc. 1996, 118, 9623; M. Könemann, G. Erker, R.
Fröhlich, S. Kotila, Organometallics 1997, 16, 2900.
[9]
[10]
[11]
[12]
[13]
[3]
[3a] K. P. Stahl, G. Boche, W. Massa, J. Organomet. Chem. 1984,
G. Erker, Acc. Chem. Res. 1984, 17, 103, and references cited
therein; K. Tatsumi, A. Nakamura, P. Hofmann, P. Stauffert,
R. Hoffmann, J. Am. Chem. Soc. 1985, 107, 4440.
G. Erker, K. Berg, L. Treschanke, K. Engel, Inorg. Chem. 1982,
21, 1277.
´
277, 113; H. J. G. Luttikhedde, R. P. Leino, C.-E. Wilen, J. H.
Näsman, M. J. Ahlgreen, T. A. Pakkanen, Organometallics
1996, 15, 3092; H. Plenio, D. Burth, J. Organomet. Chem. 1996,
519, 269; E. Barsties, S. Schaible, M.-H. Prosenc, U. Rief, W.
Röll, O. Weygand, B. Dorer, H.-H. Brintzinger, J. Organomet.
Chem. 1996, 520, 63; H. Plenio, A. Warnecke, J. Organomet.
Chem. 1997, 544, 133. For related systems see e.g.: A. Bertuleit,
C. Fritze, G. Erker, R. Fröhlich, Organometallics 1997, 16, 2891,
and references cited therein. See also (reviews): P. Jutzi, J.
Dahlhaus, Phosphorus, Sulfur Silicon Relat. Elem. 1994, 87, 73;
P. Jutzi, J. Dahlhaus, Coord. Chem. Rev. 1994, 137, 179; J.
Okuda, Comm. Inorg. Chem. 1994, 16, 185; P. Jutzi, U. Sieme-
ling, J. Organomet. Chem. 1995, 500, 175. Ϫ [3b] C. P. Casey, F.
Nief, Organometallics 1985, 4, 1218; D. Morcos, W. Tikkanen,
J. Organomet. Chem. 1989, 371, 15; W. A. Schenk, C. Labunde,
Chem. Ber. 1989, 122, 1489; J. Szymoniak, M. M. Kubicki, J.
[14] [14a]
G. Erker, K. Engel, J. L. Atwood, W. E. Hunter, Angew.
Chem. 1983, 95, 506, Angew. Chem. Int. Ed. Engl. 1983, 22, 494;
G. Erker, U. Dorf, Angew. Chem. 1983, 95, 800, Angew. Chem.
[14b]
Int. Ed. Engl. 1983, 22, 777. Ϫ
For electronically related
examples see e.g.: G. Erker, W. Frömberg, J. L. Atwood, W. E.
Hunter, Angew. Chem. 1984, 96, 72, Angew. Chem. Int. Ed. Engl.
1984, 23, 68; W. Frömberg, G. Erker, J. Organomet. Chem. 1985,
280, 343; G. Erker, U. Dorf, C. Krüger, Y.-H. Tsay, Organomet-
allics 1987, 6, 680; G. Erker, W. Frömberg, C. Krüger, E. Raabe,
J. Am. Chem. Soc. 1988, 110, 2400.
[15] [15a]
G. Erker, C. Sarter, S. Werner, C. Krüger, J. Organomet.
Chem. 1989, 377, C55; G. Erker, C. Sarter, M. Albrecht, S.
Dehnicke, C. Krüger, E. Raabe, R. Schlund, R. Benn, A. Rufin˜-
ska, R. Mynott, J. Organomet. Chem. 1990, 382, 89. Ϫ [15b] R.
Besancon, C. Moise, Inorg. Chim. Acta 1991, 180, 153; W. A.
¸
Schenk, C. Neuland-Labunde, Z. Naturforsch. 1991, 46b, 573;
18
Eur. J. Inorg. Chem. 1999, 11Ϫ19

[1,2ϪBis(N-tert-butyl-carbamoyl)cyclopentadienyl]zirconium Complexes
FULL PAPER
[19]
F. Jordan, Adv. Organomet. Chem. 1991, 32, 325, and references
Closely related 1,2-cyclopentadienyl diimine anions and their
zirconium complexes were quite recently prepared and de-
scribed independent of our work: N. Etkin, C. M. Ong, D. W.
Stephan, Organometallics 1998, 17, 3656. We thank Professor
Stephan for kindly informing us about this work prior to publi-
cation.
H. V. R. Dias, W. Jin, Z. Wang, Inorg. Chem. 1996, 35, 6074; P.
W. Roesky, Chem. Ber. 1997, 130, 859; Eur. J. Inorg. Chem. 1998,
593; M. Kira, L. C. Zhang, C. Kabuto, H. Sakurai, Organomet-
allics 1998, 17, 887; M. J. Scott, S. J. Lippard, Organometallics
1998, 17, 1769.
J. D. Scollard, D. H. McConville, J. Am. Chem. Soc. 1996, 118,
10008; J. D. Scollard, D. H. McConville, S. J. Rettig, Organome-
tallics 1997, 16, 1810; T. H. Warren, R. R. Schrock, W. M.
Davis, Organometallics 1998, 17, 308; R. R. Schrock, F. Schat-
tenmann, M. Aizenberg, W. M. Davis, J. Chem. Soc., Chem.
Commun. 1998, 199; V. C. Gibson, B. S. Kimberley, A. J. P.
White, D. J. Williams, P. Howard, J. Chem. Soc., Chem. Com-
mun. 1998, 313; L. K. Johnson, C. M. Killian, M. S. Brookart,
J. Am. Chem. Soc. 1995, 117, 6414; C. M. Killian, D. J. Tempel,
L. K. Johnson, M. S. Brookhart, J. Am. Chem. Soc. 1996, 118,
11664; B. L. Small, M. Brookhart, A. M. A. Bennett, J. Am.
Chem. Soc. 1998, 120, 4049; B. L. Small, M. Brookhart, J. Am.
Chem. Soc. 1998, 120, 7143.
cited therein.
[16]
For a compilation of reference values see e.g.: A. G. Orpen, L.
Brammer, F. H. Allen, O. Kennard, D. G. Watson, R. Taylor,
J. Chem. Soc., Chem. Commun. 1989, S1.
[17]
For structurally related zirconium complexes see e.g.: E. B.
[20]
Tjaden, D. C. Swenson, R. F. Jordan, J. L. Petersen, Organome-
tallics 1995, 14, 371; D. G. Black, D. C. Swenson, R. F. Jordan,
R. D. Rogers, Organometallics 1995, 14, 3539; J. R. Hagadorn,
J. Arnold, Organometallics 1994, 13, 4670; 1998, 17, 1355; R.
Kempe, S. Brenner, P. Arndt, Organometallics 1996, 15, 1071;
[21]
L. Matilainen, M. Klinga, M. Leskelä, J. Chem. Soc., Dalton
Trans. 1996, 219; P. Woodman, P. B. Hitchcock, P. Scott, J.
Chem. Soc., Chem. Commun. 1996, 2735; D. Walther, R.
Fischer, M. Friedrich, P. Gebhardt, H. Görls, Chem. Ber. 1996,
129, 1389; S. Pritchett, P. Gantzel, P. J. Walsh, Organometallics
1997, 16, 5130; E. Solari, C. Maltese, F. Franceschi, C. Floriani,
A. Chiesi-Villa, C. Rizzoli, J. Chem. Soc. Dalton Trans. 1997,
2903; A. Littke, N. Sleiman, C. Bensimon, D. S. Richeson, G.
A. P. Yap, S. J. Brown, Organometallics 1998, 17, 446.
[18] [18a] X. Bei, D. C. Swenson, R. F. Jordan, Organometallics 1997,
16, 3282; T. Tsukahara, D. C. Swenson, R. F. Jordan, Or-
ganometallics 1997, 16, 3303; I. Kim, Y. Nishihara, R. F. Jor-
dan, R. D. Rogers, A. L. Rheingold, G. P. A. Yap, Organomet-
[22]
allics 1997, 16, 3314. Ϫ [18b] P. B. Hitchcock, M. F. Lappert, D.-
S. Braun, H. Kalinowski, S. Berger,. 100 and More Basic NMR
Experiments, VCH, Weinheim 1996, and references cited ther-
ein.
S. Liu, J. Chem. Soc., Chem. Commun. 1994, 2637; M. F. Lap-
pert, D.-S. Liu, J. Organomet. Chem. 1995, 500, 203; B.-J. Deel-
man, P. B. Hitchcock, M. F. Lappert, H.-K. Lee, W.-P. Leung,
J. Organomet. Chem. 1996, 513, 281; M. Rahim, N. J. Taylor, S.
Xin, S. Collins, Organometallics 1998, 17, 1315.
Received August 27, 1998
[I98293]
Eur. J. Inorg. Chem. 1999, 11Ϫ19
19