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Journal of Organometallic Chemistry 588 (1999) 134 – 140
Dicyclopentadienyl zirconium and hafnium complexes with the
bridged (dimethylsilanodiyl)dicyclopentadienyl
[(SiMe
2
)(
5
-C
5
H
4
)
2
]
2 -
ligand. X-ray molecular structure of
[Zr{(SiMe
2
)(
5
-C
5
H
4
)
2
}(CH
2
Ph)]
2
(-O)
Toma ´s Cuenca, Pilar Go ´ mez-Sal, Carlos Martı ´n, Beatriz Royo, Pascual Royo *
Departamento de Quı ´mica Inorga ´nica, Edificio Farmacia, Uniersidad de Alcala ´ de Henares, Campus Uniersitario,
E-28871 Alcala ´ de Henares, Spain
Received 31 March 1999
Abstract
Reaction of the bridged (dimethylsilanediyl)dicyclopentadienyl dilithium salt [(SiMe
2
)(C
5
H
4
)
2
Li
2
] with MCl
4
, in toluene, gave
the zirconium and hafnium complexes [M{(SiMe
2
)(
5
-C
5
H
4
)
2
}Cl
2
] [M=Zr (1), Hf (2)]. Addition of two equivalents of MR
(M =MgCl, R =CH
3
; M =Li, R =CH
2
CMe
2
Ph; M =MgBz, R =CH
2
Ph) to toluene or diethyl ether solutions of
[M{(SiMe
2
)(
5
-C
5
H
4
)
2
}Cl
2
] afforded the dialkyl derivatives [M{(SiMe
2
)(
5
-C
5
H
4
)
2
}R
2
] [R =CH
3
,M=Zr (3), Hf (4); R =
CH
2
CMe
2
Ph, M=Zr (5), Hf (6); R =CH
2
Ph, M=Zr (7)]. Compound 1 reacted with LiMe and Mg(CH
2
Ph)
2
(THF)
2
in the
presence of a stoichiometric amount of water to give the -oxo derivatives [Zr{(SiMe
2
)(
5
-C
5
H
4
)
2
}R]
2
(-O) [R =CH
3
(8), CH
2
Ph
(9)]. The X-ray molecular structure of [Zr{(SiMe
2
)(
5
-C
5
H
4
)
2
}(CH
2
Ph)]
2
(-O) (9) has been determined by diffraction methods. Its
most remarkable feature is the planarity of the BzZrOZrBz and the linearity of the ZrOZr systems. © 1999 Elsevier Science
S.A. All rights reserved.
Keywords: Zirconium; Hafnium; Silanediyl-cyclopentadienyl; Chloro; Alkyl; Oxoalkyl
1. Introduction
The bis(dimethylsilanediyl)dicyclopentadienyl anion
[SiMe
2
(C
5
H
4
)
2
]
2 -
, synthesized from the corresponding
dicyclopentadiene reagent [1], has been successfully
used to stabilize Group 4 metal complexes in both high
and low oxidation states [2]. This ligand can be coordi-
nated to metal centers as a chelating group to give
dicyclopentadienyl ansa -metallocene type derivatives [3]
or in a bridging disposition to give monocyclopentadi-
enyl or mixed dicyclopentadienyl type complexes [4].
The ansa -metallocenes show different reactivity than
complexes containing independent cyclopentadienyl
rings, and this is of particular interest in reduction
reactions [5] or CH bond activation [6] at these ring
ligands. The presence of two cyclopentadienyl rings
linked by a bridging group substantially modifies the
mobility of the cyclopentadienyl ligands which subse-
quently effects the chemical behavior of the
compounds.
We are interested in the properties of these ansa -
derivatives [5,6], and describe herein the synthesis of
new chloro-, alkyl- and oxo-alkyl complexes of zirco-
nium and hafnium of the type [M{(SiMe
2
)(
5
-C
5
H
4
)
2
}-
Cl
2
], [M{(SiMe
2
)(
5
-C
5
H
4
)
2
}R
2
] and [Zr{(SiMe
2
)(
5
-
C
5
H
4
)
2
}R]
2
(-O). The X-ray molecular structure of
[Zr{(SiMe
2
)(
5
-C
5
H
4
)
2
}CH
2
Ph]
2
(-O) is also described.
2. Results and discussion
2.1. Preparatie results
Reaction of MCl
4
with the lithium reagent
[(SiMe
2
)(C
5
H
4
)
2
Li
2
] in refluxing toluene gave
* Corresponding author. Tel.: +34-91-8854765; fax: +34-91-
8854683.
E-mail address: proyo@inorg.alcala.es (P. Royo)
0022-328X/99/$ - see front matter © 1999 Elsevier Science S.A. All rights reserved.
PII:S0022-328X(99)00362-9