μ-imido, μ-(η2,η2-N,N-hydrazido) and μ-(η1-C:η2-C,N-isocyanido) dinuclear (fulvalene)zirconium derivatives

Article abstract of DOI:10.1002/1099-0682(200208)2002:8<2057::AID-EJIC2057>3.0.CO;2-P

Treatment of the chloro (fulvalene)zirconium(III) compound [Zr(η⁵-C₅H₅)(μ-Cl)]₂ [μ-(η⁵,η⁵-C₁₀H₈)] with an equimolar amount of azobenzene in toluene, under extremely anhydrous conditions, gives the μ-[bis(imido)] derivative [Zr(η⁵- C₅H₅)(μ-NPh)]₂[μ-(η⁵, η⁵-C₁₀H₈)] (1). However, when this reaction is carried out under insufficiently dry conditions a mixture of the previously reported μ-oxo complex [Zr(η⁵- C₅H₅)Cl]₂(μ-O)[μ-(η⁵, η⁵-C₁₀H₈)] and 1,2-diphenylhydrazine is obtained. When the chloro(fulvalene)zirconium(III) compound reacts with benzo[c]cinnoline the μ-(η²,η²-N,N-hydrazido) complex [Zr(η⁵-C₅H₅)Cl]₂[μ- (NC₆H₄C₆H₄N)][μ (η⁵,η⁵-C₁₀H₈)] (2a) is obtained, which rearranges to the thermodynamically more stable 2b. Addition of an equimolar amount of RNC (R = nBu, C₆H₁₁) to a toluene solution of [Zr(η⁵-C⁵H⁵)(μ-Cl)]₂ [μ-(η⁵,η⁵-C₁₀H₈)] gives [Zr(η⁵- C₅H₅)Cl]₂(μ-CNR)[μ- (η⁵,η⁵-C₁₀H₈)] [R = nBu (3), C₆H₁₁ (4)]. Reaction of [Zr(η⁵-C₅H₅)Cl]₂(μ-CNtBu) [μ-(η⁵,η⁵-C₁₀H₈)] with 1 equiv, of PhCH₂MgCl or (PhCH₂)₂Mg(THF)₂ afforded the monobenzyl derivatives [Zr(η⁵-C₅H₅)]₂ (CH₂Ph)(Cl)(μ-CNtBu) [μ-(η⁵,η⁵-C₁₀H₈)] (5 and 6). When this reaction was carried out with 2 equiv. or an excess of PhCH₂MgCl, a mixture of the monobenzyl and dibenzyl compounds [Zr(η⁵- C₅H₅)]₂(CH₂Ph)(Cl) (μ-CNtBu)[μ-(η⁵,η⁵- C₁₀H₈)] (5) and [Zr(η⁵-C₅H₅) (CH₂Ph)]₂(μ-CNtBu)[μ-(η⁵, η⁵-C₁₀H₈)] (7) is obtained. Similar reactions with 1 or 2 equiv. of (CH₃)₃SiCH₂Li afford a mixture of the monoalkyl and dialkyl compounds [Zr(η⁵-C₅H₅)]₂ [CH₂Si(CH₃)₃](Cl)(μ-CNtBu) [μ-(η⁵,η⁵-C₁₀H₈)] (8) and {Zr(η⁵-C₅H₅)[CH₂Si (CH₃)₃]}₂(μ-CNtBu) [μ-(η⁵,η⁵- C₁₀H₈)] (9) compounds. Moreover, methylation of [Zr(η⁵- C₅H₅)Cl]₂(μ-CNnBu) [μ-(η⁵,η⁵-C₁₀H₈)] gives the analytically pure tetramethyl derivative [Zr(η⁵-C₅H₅) (CH3₎]₂(μ-CNnBu) [μ-(η⁵,η⁵-C₁₀H₈)] (10), whereas [Zr(η⁵-C₅H₅)Cl]₂(μ- CNC₆H₁₁)[μ-(η⁵, μ⁵-C₁₀H₈)] reacts with MeLi to give a mixture of the monomethyl derivatives [Zr(η⁵C₅H₅)]₂ (CH₃)(Cl)(μ-CNC₆H₁₁)[μ- (η⁵,η⁵-C₁₀H₈)] (11 and 12), as well as the dimethyl compound [Zr(η⁵-C₅H₅) (CH₃)]₂(μ- CNC₆H₁₁)[μ-(η⁵, η⁵-C₁₀H₈)] (13). Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200208)2002:8<2057::AID-EJIC2057>3.0.CO;2-P

FULL PAPER
µ-Imido, µ-(η2,η2-N,N-Hydrazido) and µ-(η1-C:η2-C,N-Isocyanido) Dinuclear
(Fulvalene)zirconium Derivatives
[a]
[a]
[a]
´
´
´
Marta Gonzalez-Maupoey, Gema M. Rodrıguez, and Tomas Cuenca*
Keywords: Zirconium / Fulvalene ligands / Imido ligands / Hydrazido ligands / Isocyanido ligands
Treatment of the chloro(fulvalene)zirconium(III) compound
carried out with 2 equiv. or an excess of PhCH2MgCl, a mix-
[Zr(η5-C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)] with an equimolar
ture of the monobenzyl and dibenzyl compounds [Zr(η5-
amount of azobenzene in toluene, under extremely anhyd- C5H5)]2(CH2Ph)(Cl)(µ-CNtBu)[µ-(η5,η5-C10H8)]
(5)
[Zr(η5-C5H5)(CH2Ph)]2(µ-CNtBu)[µ-(η5,η5-C10H8)] (7) is ob-
C5H5)(µ-NPh)]2[µ-(η5,η5-C10H8)] (1). However, when this re- tained. Similar reactions with 1 or 2 equiv. of (CH3)3SiCH2Li
action is carried out under insufficiently dry conditions a mix- afford a mixture of the monoalkyl and dialkyl compounds
ture of the previously reported µ-oxo complex [Zr(η5- [Zr(η5-C5H5)]2[CH2Si(CH3)3](Cl)(µ-CNtBu)[µ-(η5,η5-C10H8)]
and
rous conditions, gives the µ-[bis(imido)] derivative [Zr(η5-
C5H5)Cl]2(µ-O)[µ-(η5,η5-C10H8)] and 1,2-diphenylhydrazine
is obtained. When the chloro(fulvalene)zirconium(III) com-
pound reacts with benzo[c]cinnoline the µ-(η2,η2-N,N-hy-
drazido) complex [Zr(η5-C5H5)Cl]2[µ-(NC6H4C6H4N)][µ-
(η5,η5-C10H8)] (2a) is obtained, which rearranges to the ther- CNnBu)[µ-(η5,η5-C10H8)] (10), whereas [Zr(η5-C5H5)Cl]2(µ-
modynamically more stable 2b. Addition of an equimolar
amount of RNC (R = nBu, C6H11) to a toluene solution
(8)
and {Zr(η5-C5H5)[CH2Si(CH3)3]}2(µ-CNtBu)[µ-(η5,η5-
C10H8)] (9) compounds. Moreover, methylation of [Zr(η5-
C5H5)Cl]2(µ-CNnBu)[µ-(η5,η5-C10H8)] gives the analytically
pure
tetramethyl
derivative
[Zr(η5-C5H5)(CH3)]2(µ-
CNC6H11)[µ-(η5,η5-C10H8)] reacts with MeLi to give a mix-
ture
of
the
monomethyl
derivatives
[Zr(η5-
of
[Zr(η5-C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)]
gives
[Zr(η5-
C5H5)]2(CH3)(Cl)(µ-CNC6H11)[µ-(η5,η5-C10H8)] (11 and 12),
as well as the dimethyl compound [Zr(η5-C5H5)(CH3)]2(µ-
CNC6H11)[µ-(η5,η5-C10H8)] (13).
C5H5)Cl]2(µ-CNR)[µ-(η5,η5-C10H8)] [R = nBu (3), C6H11 (4)].
Reaction of [Zr(η5-C5H5)Cl]2(µ-CNtBu)[µ-(η5,η5-C10H8)] with
1 equiv. of PhCH2MgCl or (PhCH2)2Mg(THF)2 afforded the
monobenzyl
derivatives
[Zr(η5-C5H5)]2(CH2Ph)(Cl)(µ-
( Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
2002)
CNtBu)[µ-(η5,η5-C10H8)] (5 and 6). When this reaction was
Introduction
tances between the two metal centres, which may even have
slight metalϪmetal interactions, as in compound I. With
this disposition the metal centres are in close proximity,
making the possible cooperative effects capable of enhan-
cing or modifying the chemical reactivity. Free rotation of
the rings around the CϪC bond in the fulvalene plane
makes two cis,trans conformations (I, II) of the metal frag-
ments possible. The preferred conformation depends mainly
on electronic and steric factors. In this type of ligand each
cyclopentadienyl group is substituted through one bond to
a second identical group. It makes the metal centre more
electron-deficient, reducing secondary reactions such as
ring CϪH bond activation because of the rigid system that
generates the fulvalene.
Complexes with cyclopentadienyl ancillary ligands have
dominated the study of early transition metal chemistry.
Mono- and dicyclopentadienyltitanium, -zirconium and -
hafnium derivatives are considered the most widely studied
organometallic transition compounds. The stability, solubil-
ity and reactivity of these complexes are dramatically influ-
enced by modifying their cyclopentadienyl ligands.[1]
The presence of two metal centres in homo- and heterodi-
metallic complexes has generated considerable effort in re-
cent years, with a myriad of studies on their properties as
well as cooperative investigations into their reactivity, which
were then compared with analogous mononuclear cyclo-
pentadienyl compounds.[2] For such organometallic com-
plexes, particular attention has been devoted to compounds
in which two metal centres are coordinated by a fulvalene
bridging ligand.[3] The fulvalene group is especially interest-
ing as it tends to form dinuclear complexes with short dis-
[a]
´
´
´
Departamento de Quımica Inorganica, Universidad de Alcala,
Campus Universitario,
´
28871 Alcala de Henares, Spain
Fax: (internat.) ϩ 34-91/885-4683
E-mail: tomas.cuenca@uah.es
Eur. J. Inorg. Chem. 2002, 2057Ϫ2063  WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0808Ϫ2057 $ 20.00ϩ.50/0
2057

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M. Gonzalez-Maupoey, G. M. Rodrıguez, T. Cuenca
FULL PAPER
Scheme 1
To enable systematic studies of such compounds we have ganic reagent to give a hydrazido intermediate species,
developed a high-yield route to titanium and zirconium which evolves through NϪN bond breaking and a sub-
compounds.[4] In recent years, the synthesis and reactivity sequent intermolecular ligand exchange to yield the final
of dinuclear organotitanium and -zirconium compounds mixture containing 1 and the chloro(fulvalene)zirconi-
containing the fulvalene ligand have been the focus of our um(IV) complex. This latter step may be favoured by the low
research[5,6] and the study of fundamental chemical reac- solubility of [Zr(η5-C5H5)Cl2]2[µ-(η5,η5-C10H8)]. Attempts
tions with a variety of new fulvalene derivatives has been to isolate and characterise the hydrazido intermediate spe-
published.[7] In this paper we report the formation of dinuc- cies by carrying out the reaction under milder conditions
lear (fulvalene)zirconium complexes where both metal have not been successful. When this reaction is carried out
atoms are bridged by an additional µ-imido, µ-(η2,η2-N,N- under insufficiently dry conditions, the final product always
hydrazido) or µ-(η1-C:η2-C,N-isocyanido) ligand.
contained a mixture of the previously reported µ-oxo com-
plex [Zr(η5-C5H5)Cl]2(µ-O)[µ-(η5,η5-C10H8)][4a] and 1,2-di-
phenylhydrazine, identified by analytical and NMR spectro-
scopic characterisation. This is consistent with the reaction
pathway shown in Scheme 1, indicating that the proposed
hydrazido intermediate species reacts with water, resulting
in the immediate hydrolysis of the ZrϪN bonds to give a
mixture of the oxo zirconium compound and hydrazine.
Several studies reveal that III is an unstable oxidation state
for zirconium. It rapidly reacts with oxygen through a per-
oxo intermediate species, which immediately transforms
into the final products, probably containing oxozirconi-
um(IV) species.[1,10] Peroxo and hydrazido are isoelectronic
and their zirconium-type derivatives are rare. In order to
determine whether a stable hydrazido complex could be
isolated, we treated the starting chlorozirconium(III) com-
pound with benzo[c]cinnoline, an organic molecule similar
to azobenzene in which the biphenyl system connecting the
nitrogen atoms prevents the NϪN bond from breaking due
to the additional CϪC bond. Equimolar amounts
of the two compounds reacted overnight in toluene
solution to give the complex [Zr(η5-C5H5)Cl]2[µ-
(η2,η2NC6H4C6H4N)][µ-(η5,η5-C10H8)] (2a), which con-
verted in toluene solution into 2b within 2 h (see Scheme 1).
Compound 2b remains unaltered under reflux in toluene
Results and Discussion
µ-Imido, µ-(η2,η2-N,N-Hydrazido) Derivatives
Imido complexes of group-4 elements have been synthe-
sized by different routes.[8] According to the described
method using the NϭN bond cleavage of an azobenzene,[9]
the known chloro(fulvalene)zirconium(III) compound
[Zr(η5-C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)][4a] reacts with an
equimolar amount of PhNϭNPh in toluene, under ex-
tremely anhydrous conditions, as shown in Scheme 1. The
initially deep violet solution first turns dark yellow and then
orange with gradual precipitation of a yellow solid. The
solid was identified by elemental analysis and IR spectro-
scopy as the known chloro(fulvalene)zirconium(IV) com-
plex [Zr(η5-C5H5)Cl2]2[µ-(η5,η5-C10H8)].[5c] This compound
is rather insoluble in the usual organic solvents and can be
separated by simple filtration. By removing the solvent in
vacuo from the resulting solution, an orange product was
obtained in 46% yield, characterized as the µ-[bis(phenylim-
ido)] derivative [Zr(η5-C5H5)(µ-NPh)]2[µ-(η5,η5-C10H8)] (1).
Complex 1 can be considered as arising from an initial
interaction of the zirconium(III) compound with the or-
2058
Eur. J. Inorg. Chem. 2002, 2057Ϫ2063

Dinuclear (Fulvalene)zirconium Derivatives
FULL PAPER
solution after 5 h. The NϪN bond cleavage and intermol- disposition. While the nature of the structure of 1 and 2 is
ecular ligand exchange processes were not observed and the of interest, all attempts to obtain crystals of crystallo-
compound was isolated as a yellow microcrystalline solid in graphic quality were unsuccessful.
60% yield.
Terminal η1-hydrazido(2Ϫ) coordination MϭNϪNR2
Both compounds are air- and moisture-sensitive and has been well established for transition metal complexes.[12]
must be manipulated under dry conditions. They are sol- There has been some concern about the nature of these spe-
uble in aromatic and chlorinated solvents and insoluble in cies and it has been noted that these compounds appear
alkanes. Formulation of 1 as an imido-bridged dinuclear closer to isodiazene (MϪNϭNR2) than hydrazido(2Ϫ) de-
compound is based on analytical and spectroscopic data rivatives.[13] Hydrazido as a bridging dianion ligand is much
and comparisons with similar structurally characterized ti- less common and has been observed in a few transition
tanium and zirconium species.[11] We propose that com- metal
derivatives
such
as
the
dinuclear
pound 2 is an unusual µ-(η2,η2-hydrazido) bridge derivat- compounds [W(NPh)Me3]2[µ-(η1,η1-NH2NH2)][µ-(η2,η2-
ive. Mass spectra confirm the dinuclear nature of these NHNH)][14] and [Sm(C5Me5)]2[µ-(η2,η2-NRNR)] (R ϭ Ph,
compounds. The presence of the fulvalene ligand must con- H).[15]
tribute to the formation and stabilization of the µ-
No reaction was observed when 2b was treated with
MeLi or MeMgCl in THF or toluene under varying condi-
(phenylimido) and µ-(η2,η2-hydrazido) disposition.
A medium-intensity absorption at 568 cmϪ1 in the IR tions; the starting substances were always recovered. The
spectrum of 2 can be assigned to the ν(NϪN) stretching lack of reactivity reflects the stability of this type of com-
mode and implies that on coordination an important reduc- pound, with its coordinatively saturated metal centres de-
tion in the NϪN multiple-bond character has taken place creasing its electrophilicity. Compound 1 must be consistent
which supports the bonding description given in Scheme 1. with a formal 18 valence electron species with 4 electrons
1
The H NMR spectrum for complex 1 (C6D6 or CDCl3, donated from each µ-imido ligand to the ‘‘Zr2’’ unit. The
room temperature) shows one singlet and three resonances hydrazido group in 2 is considered as a 6-electron ligand,
assigned to the cyclopentadienyl and the phenyl group pro- thereby also making this compound formally an 18 valence
tons, respectively. The fulvalene ligand gives two electron species.
pseudotriplets corresponding to an AAЈBBЈ spin system.
These spectroscopic features agree with the C2v symmetrical
µ-(η1-C:η2-C,N-Isocyanido) Derivatives
arrangement depicted in Scheme 1 for a dimetallic species
The
(fulvalene)bis[chloro(cyclopentadienyl)zirconium]
with the zirconium centres linked by a fulvalene ligand and fragment ‘‘(ZrCpCl)2(C10H8)’’ can provide an excellent sup-
two bridging phenylimido groups giving a central Ti2N2 port to promote uncommon ligand dispositions. Particu-
1
heterocyclic ring. The H NMR spectrum of 2a (C6D6 or larly interesting is the µ-isocyanido bonding mode found in
CDCl3, room temperature) shows one singlet and four mul- the compounds [Zr(η5-C5H5)Cl]2(µ-CNR)[µ-(η5,η5-C10H8)]
tiplets corresponding to an ABCD spin system assigned to (R ϭ tBu;[5c,5i] 2,6-Me2C6H3 [6a]), which have an unsym-
the cyclopentadienyl and fulvalene groups, respectively. The metrical bridging ligand, a µ-(η1-C:η2-C,N) 4-electron li-
phenyl protons appear as eight signals and are readily as- gand (σ,π), between their zirconium atoms. We have re-
signable (see Exp. Sect.). These spectroscopic data indicate ported the synthesis of complexes of this type by RNC ad-
the formation of a dinuclear zirconium species with a chiral dition to the dinuclear zirconium(III) derivative [Zr(η5-
ligand arrangement around each equivalent zirconium C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)].
centre, with the bridging hydrazido ligand centrally dis- pentadienyl compounds have also been described.[16]
posed and located perpendicular to the CipsoϪCipso bond of Addition of RNC (R ϭ nBu, C6H11) to a toluene solu-
Analogous
dicyclo-
the fulvalene unit and the cyclopentadienyl and chloro li- tion of [Zr(η5-C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)] (molar ratio
gands in a cis disposition. This arrangement makes the two 1:1) results in an immediate colour change from violet to
phenylhydrazido rings nonequivalent, generating eight res- bright red. After work up, compounds [Zr(η5-C5H5)Cl]2(µ-
onances for the corresponding protons. When 2a is main- CNR)[µ-(η5,η5-C10H8)] [R ϭ nBu (3), C6H11 (4)] were isol-
tained in toluene solution at room temperature, a new com- ated in high yield (ca. 80%) (Scheme 2) as red solids, charac-
1
pound 2b is formed within 2 h (Scheme 1). Its H NMR terized by analytical and spectroscopic methods. Com-
spectrum shows the same set of resonances for the cyclo- pound 4 was obtained as a partial toluene solvate, indicated
pentadienyl and the fulvalene protons observed for 2a, but by elemental analysis and 1H NMR spectroscopy. These
they are slightly shifted (see Exp. Sect.). However, the compounds are air- and moisture-sensitive and must be ma-
phenyl protons appear as four signals (two doublets of nipulated under dry conditions. They are soluble in ben-
doublets and two doublets of triplets with coupling con- zene, toluene and chloroform but insoluble in alkanes.
3
4
˜
stant values of JH-H ϭ 8 Hz and JH-H ϭ 0.97 Hz). Com- Characteristic absorptions at ν ϭ 1656 [1650(sh)] and 1637
pounds 2a and 2b offer identical elemental analyses, IR and cmϪ1 due to ν(CϭN) vibrations are observed in the IR
mass spectroscopic data. These observations may be ex- spectra of 3 and 4, similar to those found for other com-
plained by an enantiomeric isomerization process, if the li- pounds of this type.[5i,6a,7c] The H NMR spectra in CDCl3
1
gands bonded to one of the zirconium centres re-coordinate at room temperature show the expected two ABCD spin
in 2a to give the thermodynamically more stable 2b, in systems for the fulvalene protons and two signals for the
which the cyclopentadienyl and chloro ligands adopt a trans cyclopentadienyl rings, consistent with a dinuclear species
Eur. J. Inorg. Chem. 2002, 2057Ϫ2063
2059

´
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M. Gonzalez-Maupoey, G. M. Rodrıguez, T. Cuenca
FULL PAPER
with two zirconium atoms each in a different coordination C5H5)]2[CH2Si(CH3)3]2(µ-CNtBu)[µ-(η5,η5-C10H8)]
(9).
environment. Characteristic resonances for the cyclohexyl Moreover, when [Zr(η5-C5H5)Cl]2(µ-CNnBu)[µ-(η5,η5-
and n-butyl groups are also observed. The spectrum of 3 C10H8)] was treated in toluene with 2 equiv. of MeLi, the
also shows an AB spin system for the diastereotopic dimethyl
complex
[Zr(η5-C5H5)(CH3)]2(µ-CNnBu)[µ-
‘‘NϪCH2’’ protons. Similar spectroscopic features were ob- (η5,η5-C10H8)] (10) was isolated as an analytically pure sub-
served in the 13C NMR spectra. The resonance for the iso- stance, unlike the mixture of the monomethyl and dimethyl
cyanide carbon atom (CNϪ) is observed at δ ϭ 295.0 ppm compounds obtained in the methylation of [Zr(η5-
in compound 3 but not observed for 4.
C5H5)Cl]2(µ-CNtBu)[µ-(η5,η5-C10H8)].[7c]
Reaction
of
[Zr(η5-C5H5)Cl]2(µ-CNC6H11)[µ-(η5,η5-C10H8)] with MeLi
in a molar ratio of 1:2 gave the dimethyl compound [Zr(η5-
C5H5)(CH3)]2(µ-CNC6H11)[µ-(η5,η5-C10H8)] (13), which
was always obtained with small amounts of the monome-
thyl derivatives [Zr(η5-C5H5)]2(CH3)(Cl)(µ-CNC6H11)[µ-
(η5,η5-C10H8)] (11 and 12). Attempts to separate this mix-
ture by repeated recrystallization were unsuccessful.
Compounds 5Ϫ13 are moisture-sensitive but thermally
stable in the solid state, allowing them to be stored under
inert conditions for weeks. They are soluble in aromatic hy-
drocarbons, THF, dichloromethane and chloroform, but in-
soluble in diethyl ether and alkanes. The pairs of com-
pounds obtained, 5/6, 5/7 and 8/9, and the compounds
11Ϫ13, show the same solubility in all common solvents
and therefore could not be separated. Consequently, they
have been characterized by NMR spectroscopy but satis-
factory elemental analyses were not obtained; 10 can be
obtained as a pure compound and has been analytically and
spectroscopically identified.
Scheme 2
Alkylation of [Zr(η5-C5H5)Cl]2(µ-CNR)[µ-(η5,η5-C10H8)]
(R
ϭ ϭ Me,
tBu,[5i] nBu, C6H11) with RЈM [RЈ
CH2Si(CH3)3, M ϭ Li; RЈ ϭ (PhCH2)2, (PhCH2)Cl, M ϭ
The 1H NMR spectra of complexes 5Ϫ13 in C6D6 at
room temperature show two ABCD spin systems (eight sig-
nals) for the fulvalene ligand and two signals for the cyclo-
pentadienyl ring protons. The expected resonances for the
protons of the isocyanide alkyl substituents are observed.
The spectra of 5Ϫ9 show one singlet for the tert-butyl pro-
tons. Four signals are assigned to the n-butyl protons in
10 with the ‘‘NCH2Ϫ’’ methylene groups as diastereotopic
protons and four signals are assigned to the cyclohexyl pro-
tons in 13. These spectroscopic data indicate the formation
of dinuclear zirconium compounds with the metal atoms in
Scheme 3
Mg] was also studied (Scheme 3). [Zr(η5-C5H5)Cl]2(µ- nonequivalent coordination environments.
CNtBu)[µ-(η5,η5-C10H8)] reacts with
1
equiv. of The ‘‘CH2Ph’’ methylene group protons appear as AB
PhCH2MgCl or (PhCH2)2Mg(THF)2 to afford an orange spin systems with two doublets for 5 and 6 (δ ϭ 2.05, 1.17
1
yellow oil. Its H NMR spectrum in C6D6 indicated a mix- ppm and δ ϭ 2.82, 2.50 ppm, respectively) and four doub-
ture containing the two isomers of the monobenzyl deri- lets for 7 (δ ϭ 2.82, 2.58, 2.15, 1.37 ppm) suggesting the
vatives
[Zr(η5-C5H5)]2(CH2Ph)(Cl)(µ-CNtBu)[µ-(η5,η5- presence of CH2 diastereotopic groups. Two of the chemical
C10H8)] (5 and 6) in a 1:3 molar ratio. When the reaction shifts of the methylene groups in 7 (δ ϭ 2.15 and 1.37 ppm)
was carried out with 2 equiv. or an excess of PhCH2MgCl, compare well with the signals for the same protons in 5
a mixture of the monobenzyl compound 5 and the di- (δ ϭ 2.05 and 1.17 ppm), while the other two methylene
benzyl
(η5,η5-C10H8)] (7) (30%:70%) was obtained. In an attempt corresponding signals in 6 (δ ϭ 2.82 and 2.50 ppm). These
to isolate pure monoalkyl complex, the bulkier spectroscopic features suggest that the CH2 groups in each
complex
[Zr(η5-C5H5)(CH2Ph)]2(µ-CNtBu)[µ- groups in 7 (δ ϭ 2.82 and 2.58 ppm) compare with the
a
(CH3)3SiCH2Li was used as an alkylating reagent, but the pair of compounds occupy very similar chemical environ-
final results were similar to those found with the benzyl ments and must be bonded to the same type of zirconium
and the previously reported methyl reagents.[7c] The starting atom. The presence of the bridging isocyanido group can
dichloro compound reacted with
(CH3)3SiCH2Li in toluene at room temperature for 16 h to lene derivatives. The η2-side-on coordination of the isocyan-
give
mixture of the monoalkyl complex [Zr(η5- ido bridge[5i] to one of the zirconium atoms involves dona-
1 or 2 equiv. of exert an important influence in the reactivity of these fulva-
a
C5H5)]2[CH2Si(CH3)3](Cl)(µ-CNtBu)[µ-(η5,η5-C10H8)] (8) tion of the nitrogen atom’s free electron pair to the metal
and
the
dialkyl
compound
[Zr(η5- centre to give an 18-electron valence shell. The increase of
Eur. J. Inorg. Chem. 2002, 2057Ϫ2063
2060

Dinuclear (Fulvalene)zirconium Derivatives
FULL PAPER
the electronic density at this zirconium centre must cause C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)]. Alkylation reactions of the
shielding of the NMR signals for all of the directly bonded chloro(fulvalene)isocyanido complexes show important dif-
ligands.[7c] These observations allow the structures of 5 and ferences in the reactivity of both chloride ions present in
6 to be distinguished (Scheme 4).
the
[Zr(η5-C5H5)Cl]2(µ-CNR)[µ-(η5,η5-C10H8)]
com-
pounds.
Experimental Section
General Remarks: All manipulations were performed under argon
using Schlenk and high-vacuum line techniques or a glovebox
model HE-63. The solvents were purified by distillation under ar-
gon before use, by employing the appropriate drying/deoxygenating
˚
agent. Deuterated solvents were stored over activated 4 A molecu-
lar sieves and degassed by several freeze-thaw cycles. Azobenzene,
benzo[c]cinnoline, n-butyl isocyanide, cyclohexyl isocyanide,
BzMgCl and MeLi (Aldrich) were purchased from commercial
sources and used without further purification. [Zr(η5-C5H5)(µ-
Cl)]2[µ-(η5,η5-C10H8)],[4a]
[Zr(η5-C5H5)Cl]2(µ-CNtBu)[µ-(η5,η5-
C10H8)],[5i] (CH3)3SiCH2Li[17] and Bz2Mg(THF)2 [18] were prepared
by known procedures. C,H, N microanalyses were performed with
a PerkinϪElmer 240B and/or a Heraeus CHN-O-Rapid microana-
lyzer. IR spectra were recorded with a PerkinϪElmer Spectrum
2000 spectrophotometer by using KBr pellets; only selected IR data
are reported. NMR spectra, measured at 25 °C, were recorded with
a Varian Unity 300 (1H at 300 MHz and 13C at 75 MHz) and a
500 Plus (1H at 300 MHz and 13C at 125 MHz) spectrometer and
chemical shifts are referenced to residual proton and carbon signals
of the solvent.
[Zr(η5-C5H5)(µ-NPh)]2[µ-(η5,η5-C10H8)] (1): 1.7 g (9.7 mmol) of
PhNϭNPh was added at room temperature to a solution of 5 g
(9.7 mmol) of [Zr(η5-C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)] in toluene
(100 mL). The reaction mixture was heated under reflux (80 °C)
and stirred for 12 h. The deep violet solution first turned dark yel-
low and then changed into a suspension of a yellow solid in an
orange solution. After cooling, the yellow solid was separated by
filtration and identified as [Zr(η5-C5H5)Cl2]2[µ-(η5,η5-C10H8)] by
IR spectroscopy and elemental analysis (1.8 g, 63% yield). The re-
sulting solution was concentrated to 10 mL and cooled to Ϫ30 °C
overnight to give compound 1 as a yellow-orange microcrystalline
solid. The compound was recrystallised from toluene/hexane (1.4 g,
46% yield). 1H NMR (500 MHz, C6D6, 25 °C): δ ϭ 6.04, 5.65
(AAЈBBЈ spin system, 4 ϩ 4 H, J ϭ 2.7 Hz, C10H8), 5.97 (s, 10 H,
C5H5), 7.18 (t, 4 H, Ph), 6.77 (t, 2 H, Ph), 6.04 (d, 4 H, Ph) ppm.
1H NMR (500 MHz, CDCl3, 25 °C): δ ϭ 6.21 (s, 10 H, C5H5),
6.19, 6.05 (AAЈBBЈ spin system, 4 ϩ 4 H, J ϭ 2.7 Hz, C10H8), 7.07
(t, 4 H, Ph), 6.59 (t, 2 H, Ph), 5.95 (d, 4 H, Ph) ppm. C32H28N2Zr2
(623.06): calcd. C 61.69, H 4.50, N 4.50; found C 61.34, H 4.55,
N 3.75.
Scheme 4
Similar spectroscopic behaviour has been observed in the
1H NMR spectrum (C6D6, room temperature) for the dias-
tereotopic ‘‘CH2SiMe3’’ methylene group protons for com-
pounds 8 and 9 (one and two AB spin systems respectively;
see Exp. Sect.). Two markedly different chemical shifts are
found for the methyl protons in the dimethyl derivatives 10
(δ ϭ 0.29 and Ϫ0.37 ppm) and 13 (δ ϭ 0.29 and Ϫ0.32
ppm).
These experimental results highlighted differences in the
reactivity of the two ZrϪCl bonds present in the starting
[Zr(η5-C5H5)Cl]2(µ-CNR)[µ-(η5,η5-C10H8)]
compounds
and allow us to conclude that the ease of alkylation of the
chloride ion bonded to the tetracoordinated zirconium
atom is greater than the alkylation of the chloride ion bon-
ded to the pentacoordinated zirconium atom. This proposal
is consistent with the results obtained in the methylation
reactions of the dichloro compound [Zr(η5-C5H5)Cl]2(µ-
CNtBu)[µ-(η5,η5-C10H8)].[7c]
[Zr(η5-C5H5)Cl]2[µ-(η2,η2-NC6H4C6H4N)][µ-(η5,η5-C10H8)]
(2):
1.2 g (6.8 mmol) of benzo[c]cinnoline was added at room temper-
ature to a solution of 3.5 g (6.8 mmol) of [Zr(η5-C5H5)(µ-Cl)]2[µ-
(η5,η5-C10H8)] in toluene (100 mL). The reaction mixture was
heated under reflux and stirred for 12 h. The deep violet solution
slowly turned orange-yellow. After cooling and filtration, the re-
sulting solution was concentrated to 10 mL and cooled to Ϫ30 °C
overnight to give compound 2 as a yellow microcrystalline solid.
The compound was recrystallised from toluene/hexane (2.8 g, 60%
yield). 2a: IR (KBr): ν˜ ϭ 568 cmϪ1 [ν(NϪN)]. 1H NMR (500 MHz,
C6D6, 25 °C): δ ϭ 6.93, 5.92, 5.82, 5.54 (ABCD spin system, 4 ϫ
2 H, C10H8), 5.58 (s, 10 H, C5H5), 8.18 (dd, 1 H, Ph), 7.25 (dd, 1
Conclusion
This report shows that dinuclear zirconium(IV) com-
plexes, containing one fulvalene and one additional group
(imido, η2,η2-N,N-hydrazido or η1-C:η2-C,N-isocyanido)
as bridging ligands, can be synthesized by adding neutral
organic reagents (azobenzene, benzo[c]cinnoline, isocyan-
ide) to the easily accessible zirconium(III) derivative [Zr(η5- H, Ph), 7.17 (dd, 1 H, Ph), 7.13 (t, 1 H, Ph), 7.04 (t, 1 H, Ph), 6.70
Eur. J. Inorg. Chem. 2002, 2057Ϫ2063 2061

´
´
M. Gonzalez-Maupoey, G. M. Rodrıguez, T. Cuenca
FULL PAPER
(dd, 1 H, Ph), 6.69 (t, 1 H, Ph), 6.67 (t, 1 H, Ph) ppm. H NMR
(500 MHz, CDCl3, 25 °C): δ ϭ 6.83, 6.65, 6.33, 5.83 (ABCD spin
system, 4 ϫ 2 H, C10H8), 5.71 (s, 10 H, C5H5), 7.68 (dd, 1 H, Ph),
1
C10H8)] (1.46 g, 2.45 mmol) in toluene (50 mL) at Ϫ78 °C. The
reaction mixture was warmed to room temperature and stirred for
18 h with formation of an MgCl2 precipitate. After filtration, the
7.59 (dd, 1 H, Ph), 7.46 (dd, 1 H, Ph), 7.27 (t, 1 H, Ph), 7.17 (t, 1 solvent was removed and an orange yellow solid was obtained
H, Ph), 7.08 (dd, 1 H, Ph), 6.91 (t, 1 H, Ph), 6.82 (t, 1 H, Ph) ppm. which was washed with diethyl ether and hexane. Recrystallization
2b: IR (KBr): ν˜ ϭ 568 cmϪ1 [ν(NϪN)]. 1H NMR (500 MHz, C6D6, from toluene/hexane gave an orange yellow microcrystalline solid.
25 °C): δ ϭ 7.43, 6.97, 5.54, 5.17 (ABCD spin system, 4 ϫ 2 H, 5 and 6 have the same composition and therefore they must have
C10H8), 5.51 (s, 10 H, C5H5), 7.61 [dd, 3JH-H ϭ 8, 4JH-H ϭ 0.97 Hz, an identical elemental analysis. However, the isolated final solid
3
4
2 H, Ph(A)], 7.19 [dd, JH-H ϭ 8, JH-H ϭ 0.97 Hz, 2 H, Ph(D)],
consisted mainly of 5 and 6, but it contained a small amount of
7.11 [dt, 3JH-H ϭ 8, 4JH-H ϭ 0.97 Hz, 2 H, Ph(B)], 6.68 (dt, 3JH-H ϭ unidentified impurities that could not be removed, and satisfactory
4
8, JH-H ϭ 0.97 Hz, 2 H, Ph(C) ppm; the numbering assignment is
elemental analysis was not obtained. Spectroscopic data showed
shown in Scheme 5. 13C NMR (125 MHz, C6D6, 25 °C). δ ϭ 122.9,
the presence of 5 (25%) and 6 (75%). 6: 1H NMR (500 MHz, C6D6,
121.0, 113.3, 110.4 (C10H8), 115.3 (C5H5), 101.2 (Cipso, C10H8), 25 °C): δ ϭ 7.40Ϫ6.98 (m, 5 H, CH2Ph), 5.70, 5.66 (s, 2 ϫ 5 H,
135.7, 131.6, 129.1 ppm, and signals collapsed by the C6D6 reson- C5H5), 6.50, 6.36, 5.76, 5.65, 5.05, 4.46, 4.41, 4.40 (two ABCD spin
ances. C32H26Cl2N2Zr2 (691.95): calcd. C 55.54, H 3.79, N 4.05; systems, 8 ϫ 1 H, C10H8), 2.82, 2.50 (AB spin system, 2 ϫ 1 H,
found C 56.06, H 3.96, N 3.63.
CH2Ph), 1.03 (s, 9 H, tBuNC) ppm. 5: 1H NMR (500 MHz, C6D6,
25 °C): δ ϭ 7.40Ϫ6.98 (m, 5 H, CH2Ph), 5.63, 5.38 (s, 2 ϫ 5 H,
C5H5), 5.57, 5.55, 5.45, 5.27, 5.06, 4.86, 4.60, 4.48 (two ABCD spin
systems, 8 ϫ 1 H, C10H8), 2.05, 1.17 (AB spin system, 2 ϫ 1 H,
CH2Ph), 1.33 (s, 9 H, tBuNC) ppm.
[Zr(η5-C5H5)]2(CH2Ph)(Cl)(µ-CNtBu)[µ-(η5,η5-C10H8)] (5) and
[Zr(η5-C5H5)(CH2Ph)]2(µ-CNtBu)[µ-(η5,η5-C10H8)] (7): According
to the same procedure described for the preparation of 5 ϩ 6, using
2.46 mL of a 2  solution of BzMgCl in THF (4.90 mmol) and
1.46 g (2.45 mmol) of [Zr(η5-C5H5)Cl]2(µ-CNtBu)[µ-(η5,η5-C10H8)]
a mixture of 5 (30%) ϩ 7 (70%) was obtained and spectroscopically
characterized. 5 and 7 have the same solubility in all common solv-
Scheme 5
[Zr(η5-C5H5)Cl]2(µ-CNnBu)[µ-(η5,η5-C10H8)] (3):
A solution of
[Zr(η5-C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)] (1.00 g, 1.94 mmol) in 75 mL ents. They could not be separated and satisfactory elemental ana-
of toluene was treated at room temperature with n-butyl isocyanide
(0.20 mL, 2.00 mmol). The violet solution turned red within an hour.
After filtration, the solvent was completely removed in vacuo and
the resulting red solid washed with n-hexane. After recrystallization
lyses were not obtained. 7: 1H NMR (500 MHz, C6D6, 25 °C): δ ϭ
7.40Ϫ6.98 (m, 5 H, CH2Ph), 5.41, 5.38 (s, 2 ϫ 5 H, C5H5), 6.60,
6.50, 5.29, 5.14, 4.99, 4.48, 4.46, 4.40 (two ABCD spin systems, 8
ϫ 1 H, C10H8), 2.82, 2.58, 2.15, 1.37 (two AB spin systems, 4 ϫ 1
from toluene/hexane, a sample of 3 suitable for analysis was obtained H, CH2Ph), 1.06 (s, 9 H, tBuNC) ppm.
1
(1.04 g, 90%). IR (KBr): ν˜ ϭ 1656 [1650 (sh)] cmϪ1 [ν(CϭN)]. H
[Zr(η5-C5H5)]2[CH2Si(CH3)3](Cl)(µ-CNtBu)[µ-(η5,η5-C10H8)] (8)
NMR (300 MHz, CDCl3, 25 °C): δ ϭ 6.18, 5.82 (s, 2 ϫ 5 H, C5H5),
6.41, 6.40, 6.28, 6.00, 5.63, 5.40, 4.83, 4.78 (two ABCD spin systems,
8 ϫ 1 H, C10H8), 3.88, 3.35 (AB spin system, 2 ϫ 1 H,
NϪCH2Ϫ[CH2]2ϪCH3), 1.85 (m, 2 H, NϪCH2ϪCH2ϪCH2ϪCH3),
and [Zr(η5-C5H5)]2[CH2Si(CH3)3]2(µ-CNtBu)[µ-(η5,η5-C10H8)] (9):
0.09 g (1.0 mmol) of (CH3)3SiCH2Li was added to a solution of
[Zr(η5-C5H5)Cl]2(µ-CNtBu)[µ-(η5,η5-C10H8)] (0.6 g, 1.0 mmol) in
toluene (50 mL) at Ϫ78 °C. The reaction mixture was warmed to
room temperature and stirred for 16 h with the formation of an
LiCl precipitate. After filtration, the solvent was removed and a
red solid was obtained which was washed with diethyl ether and
hexane. Recrystallization from toluene/hexane gave an orange mi-
crocrystalline solid identified as a mixture of 8 ϩ 9 (molar ratio
2:1) with the presence of a small amount of the starting zirconium
compound. When 0.19 g (2.0 mmol) of (CH3)3SiCH2Li was used
1.46 (m,
2 H, NϪCH2ϪCH2ϪCH2ϪCH3), 1.03 (t, 3 H,
NϪCH2ϪCH2ϪCH2ϪCH3) ppm. 13C NMR (75 MHz, CDCl3, 25
°C): δ ϭ 295.0 (CNnBu), 133.2, 120.4 [Cipso, C10H8], 122.3, 117.1,
105.4, 102.7, 101.8, 101.4, 100.1, 95.6 (C10H8), 109.76, 108.62
(C5H5), 57.7, 31.7, 20.8, 14.0 (CNnBu) ppm. C25H27Cl2NZr2
(594.87): calcd. C 50.48, H 4.57, N 2.35; found C 50.01, H 4.67,
N 2.15.
[Zr(η5-C5H5)Cl]2(µ-CNC6H11)[µ-(η5,η5-C10H8)] (4): According to to react with 0.6 g (1.0 mmol) of [Zr(η5-C5H5)Cl]2(µ-CNtBu)[µ-
the procedure described for 3, 1.93 g (3.75 mmol) of [Zr(η5- (η5,η5-C10H8)] a mixture of 8 ϩ 9 (molar ratio 1:3) with no traces
C5H5)(µ-Cl)]2[µ-(η5,η5-C10H8)] and 0.48 mL (3.77 mmol) of cyclo- of the starting zirconium compound was obtained. 8 and 9 have
hexyl isocyanide were allowed to react in 150 mL of toluene to give
4 (2.25 g, 97%) as a partial toluene solvate, indicated by elemental
analysis and 1H NMR spectroscopy. IR (KBr): ν˜ ϭ 1637 cmϪ1
the same solubility in all common solvents. They could not be sep-
arated and satisfactory elemental analyses were not obtained. Spec-
troscopic data showed the presence of 8 (25%) ϩ 9 (75%). 8: 1H
NMR (500 MHz, C6D6, 25 °C): δ ϭ 5.64, 5.62 (s, 2 ϫ 5 H, C5H5),
1
[ν(CϭN)]. H NMR (300 MHz, CDCl3, 25 °C): δ ϭ 6.18, 5.81 (s,
2 ϫ 5 H, C5H5), 6.41, 6.37, 6.28, 5.98, 5.64, 5.42, 4.96, 4.82 (two 6.58, 6.26, 5.72, 5.50, 5.40, 5.39, 4.86, 4.70 (two ABCD spin sys-
ABCD spin systems, 8 ϫ 1 H, C10H8), 3.85, 1.86, 1.29 (C6H11)
tems, 8 ϫ 1 H, C10H8), 1.37 (s, 9 H, CNtBu), 0.20 (s, 9 H, SiMe3),
ppm. 13C NMR (75 MHz, CDCl3, 25 °C): δ ϭ 119.9, 113.5 (Cipso
,
Ϫ0.19, Ϫ0.40 (AB spin system, CH2SiMe3) ppm. 9: 1H NMR (500
C10H8), 123.4, 117.5, 104.8, 102.5, 101.8, 101.1, 100.8, 95.7 MHz, C6D6, 25 °C): δ ϭ 5.65, 5.47 (s, 2 ϫ 5 H, C5H5), 6.38, 6.32,
(C10H8), 109.8, 109.0 (C5H5), 67.5, 32.8, 32.3, 25.2 [CN(C6H11)] 5.60, 5.44, 5.20, 4.58, 4.55, 4.40 (two ABCD spin systems, 8 ϫ 1
ppm. C27H29Cl2NZr2·1/2toluene (666.98): calcd. C 54.88, H 4.95, H, C10H8), 1.08 (s, 9 H, CNtBu), 0.42, 0.29 (s, 9 ϫ 2 H, SiMe3),
N 2.10; found C 54.74, H 5.01, N 2.06. 0.33, 0.11, Ϫ0.05, Ϫ0.37 (two AB spin systems, CH2SiMe3) ppm.
[Zr(η5-C5H5)]2(CH2Ph)(Cl)(µ-CNtBu)[µ-(η5,η5-C10H8)] (5 and 6): [Zr(η5-C5H5)(CH3)]2(µ-CNnBu)[µ-(η5,η5-C10H8)] (10): 1.12 mL of
1.23 mL of a 2  solution of BzMgCl in THF (2.45 mmol) was
a 1.50  solution of LiMe in diethyl ether (1.70 mmol) was added
added to
2062
a
solution of [Zr(η5-C5H5)Cl]2(µ-CNtBu)[µ-(η5,η5-
at Ϫ78 °C to a solution of [Zr(η5-C5H5)Cl]2(µ-CNnBu)[µ-(η5,η5-
Eur. J. Inorg. Chem. 2002, 2057Ϫ2063

Dinuclear (Fulvalene)zirconium Derivatives
FULL PAPER
W. A. Herrmann, T. Cuenca, U.
[5b]
lics 1986, 5, 2514Ϫ2516.
C10H8)] (0.50 g, 0.84 mmol) in toluene (50 mL). The reaction mix-
ture was stirred for 30 min and warmed to room temperature. After
filtration, the solvent was removed and an orange-yellow solid was
obtained. Recrystallization from toluene/hexane gave 10 as a mi-
crocrystalline solid (0.21 g, 46%). IR (KBr): ν˜ ϭ 1660 [1620 (sh)]
cmϪ1 [ν(CϭN)]. 1H NMR (500 MHz, C6D6, 25 °C): δ ϭ 5.58, 5.44
(s, 2 ϫ 5 H, C5H5), 5.97, 5.94, 5.36, 5.33, 5.13, 4.57, 4.42, 4.12 (two
ABCD spin systems, 8 ϫ 1 H, C10H8), 3.41, 2.89 (AB spin system,
NϪCH2Ϫ[CH2]2ϪCH3), 1.57 (m, NϪCH2ϪCH2ϪCH2ϪCH3),
[5c]
Küsthardt, J. Organomet. Chem. 1986, 309, C15ϪC17.
W.
´
A. Herrmann, T. Cuenca, B. Menjon, E. Herdtweck, Angew.
[5d]
Chem. Int. Ed. Engl. 1987, 26, 697Ϫ699.
M. M. Rohmer,
M. Benard, Organometallics 1991, 10, 157Ϫ163. [5e] Y. Wielstra,
S. Gambarotta, A. Meetsma, J. L. de Boer, Organometallics
1989, 8, 250Ϫ251. [5f] Y. Wielstra, S. Gambarotta, A. Meetsma,
[5g]
A. L. Spek, Organometallics 1989, 8, 2948Ϫ2952.
Y. Wiel-
stra, A. Meetsma, S. Gambarotta, S. Khan, Organometallics
1990, 9, 876Ϫ879. [5h] Y. Wielstra, S. Gambarotta, A. L. Spek,
[5i]
W. J. J. Smeets, Organometalics 1990, 9, 2142Ϫ2148.
W. A .
1.23
(m,
NϪCH2ϪCH2ϪCH2ϪCH3),
0.89
(t,
NϪCH2ϪCH2ϪCH2ϪCH3), 0.29, Ϫ0.37 (s, ZrϪCH3) ppm. 13C
NMR (125 MHz, C6D6, 25 °C): δ ϭ 116.2, 111.9 (Cipso, C10H8),
116.6, 110.0, 101.8, 101.0, 99.9, 97.6, 96.7, 92.8 (C10H8), 105.7,
105.6 (C5H5), 57.9, 32.3, 21.0, 14.2 (CNnBu), 13.4, 9.5 (ZrϪCH3)
ppm. C27H33NZr2 (554.04): calcd. C 58.54, H 5.96, N 2.53; found
C 58.11, H 6.12, N 2.29.
´
Herrmann, B. Menjon, E. Herdtweck, Organometallics 1991,
10, 2134Ϫ2142.
[6] [6a]
´
´
´
T. Cuenca, R. Gomez, P. Gomez-Sal, G. M. Rodrıguez, P.
Royo, Organometallics 1992, 11, 1229Ϫ1234. [6b] L. M. Alvaro,
J. C. Flores, T. Cuenca, P. Royo, M. A. Pellinghelli, A. Tiripic-
[6c]
chio, Organometallics 1992, 11, 3301Ϫ3306.
A. Cano, T.
´
Cuenca, G. Rodrıguez, P. Royo, C. Cardin, D. J. Wilcok, J.
A. Cano, T. Cuenca,
M. Galakhov, G. M. Rodrıguez, P. Royo, C. Cardin, M. A.
[6d]
Organomet. Chem. 1993, 447, 51Ϫ57.
[Zr(η5-C5H5)]2(CH3)(Cl)(µ-CNC6H11)[µ-(η5,η5-C10H8)] (11 ؉ 12)
and [Zr(η5-C5H5)(CH3)]2(µ-CNC6H11)[µ-(η5,η5-C10H8)] (13): 1.0
mL of a 1.50  solution of MeLi in diethyl ether (1.5 mmol) was
added to a solution of [Zr(η5-C5H5)Cl]2(µ-CNC6H10)[µ-(η5,η5-
C10H8)] (0.5 g, 0.75 mmol) in toluene (50 mL) at Ϫ78 °C. The reac-
tion mixture was warmed to room temperature and stirred for 16 h
with formation of an LiCl precipitate. After filtration, the solvent
was removed and a red solid was obtained which was washed with
hexane. Recrystallization from toluene/hexane gave a red solid
identified by NMR spectroscopy as a mixture of 11 ϩ 12 ϩ 13
(molar ratio 1:1:4). They could not be separated and satisfactory
elemental analyses were not obtained. 13: 1H NMR (500 MHz,
C6D6, 25 °C): δ ϭ 5.60, 5.43 (s, 2 ϫ 5 H, C5H5), 5.96, 5.94, 5.36,
5.32, 5.15, 4.60, 4.58, 4.19 (two ABCD spin systems, 8 ϫ 1 H,
C10H8), 3.60 (m, 1 H, ipso-C6H11), 2.00Ϫ1.00 (C6H11), 0.29, Ϫ0.32
(s, ZrϪCH3) ppm.13C NMR (125 MHz, C6D6, 25 °C): δ ϭ 115.9,
111.7 (Cipso, C10H8), 117.4, 110.4, 101.7, 100.8, 99.2, 98.0, 97.7,
92.9 (C10H8), 106.0, 105.6 (C5H5), 65.8, 33.8, 33.1, 25.8 (C6H11),
14.4, 9.8 (ZrϪCH3) ppm.
´
[6e]
Convery, J. Organomet. Chem. 1995, 493, 17Ϫ25.
M. Gon-
´
´
zalez-Maupoey, G. M. Rodrıguez, T. Cuenca, J. Organomet.
Chem. 2001, 645, 112Ϫ117.
[7] [7a]
M. Bochmann, T. Cuenca, D. T. Hardy, J. Organomet.
[7b]
Chem. 1994, 484, C10ϪC12.
T. Cuenca, M. Galakhov, G.
´
Jimenez, E. Royo, P. Royo, J. Organomet. Chem. 1997, 543,
[7c]
209Ϫ215.
E. Royo, M. Galakhov, P. Royo, T. Cuenca, Or-
ganometallics 2000, 19, 3347Ϫ3353. [7d] E. Royo, M. Galakhov,
[7e]
P. Royo, T. Cuenca, Organometallics 2000, 19, 5559Ϫ5567.
E. Royo, P. Royo, T. Cuenca, M. Galakhov, J. Organomet.
Chem. 2001, 634, 177Ϫ184.
[8]
D. J. Arney, M. A. Bruck, S. R. Huber, D. E. Wigley, Inorg.
Chem. 1992, 31, 3749Ϫ3755 and references cited there in.
[9] [9a]
J. E. Hill, R. D. Profilet, P. E. Fanwick, I. P. Rothwell,
[9b]
Angew. Chem. Int. Ed. Eng. 1990, 29, 664Ϫ665.
J. E. Hill,
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