Journal of Organometallic Chemistry 630 (2001) 215 – 220
www.elsevier.com/locate/jorganchem
Isolation of a diketone species that is allylically bound to
tungsten, and its relationship to a tungsten
2
-ketone complex
Michael J. Chetcuti
a,
*, Phillip E. Fanwick
b
, Brian E. Grant
a
a
Department of Chemistry and Biochemistry, Uniersity of Notre Dame, Notre Dame, IN 46556, USA
b
Department of Chemistry, Purdue Uniersity, West Lafayette, IN 47907, USA
Received 13 March 2001; received in revised form 27 May 2001; accepted 27 May 2001
Abstract
The diketone complex [W(CO)
2
(-C
5
H
4
Me){
3
-C(O)C (Ph)C (H)C (Ph)C
(H)C(O)C
5
Me
5
}] (3) was isolated from the
reaction of PhC
2
H with a mixture of [Ni(CO)I(-C
5
Me
5
)] and [W(CO)
3
(-C
5
H
4
Me)]
−
. Complex 3 contains an organic diketone
fragment that is bound in a -allyl fashion to a tungsten atom. It was fully characterized by standard spectroscopic techniques
and by a single-crystal X-ray diffraction study. The relationship of complex 3 to a structurally characterized cyclopentadienyl
tungsten
2
-ketone species 1, and the likelihood that 3 and the methylcyclopentadienyl analog of 1 share common intermediates,
are discussed. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Allyl complexes; Ketone; Nickel; Tungsten; Carbon – carbon coupling
1. Introduction
The exploration of the chemistry of alkynes with
organometallic complexes remains a fertile research
area [1]. We have reported some of the rich chemistry
that Ni–Mo and Ni–W hetero-bimetallic species
demonstrate with alkynes [2]. We have also looked into
the reactions of mixtures of the monometallic precur-
sors of the hetero-bimetallic compounds with alkynes.
When an in situ mixture of [M(CO)
3
(-C
5
H
5
)]
−
(M =Mo, W) and [Ni(CO)I(-C
5
Me
5
)] is treated with
PhC
2
H, unusual products which contain many new
carboncarbon bonds have been isolated [3,4]. Among
them is the 16-electron tungsten side-bound
2
-ketone
complex 1 [3], which contains a pentamethylcyclopenta-
diene (C
5
Me
5
) group that has been the recipient of a
Diels – Alder added PhC
2
H ligand. This adduct forms
one of the two alkyl groups of the
2
-ketone ligand.
The other ketonic group is formed by cyclo-oligomer-
ization of three PhC
2
H ligands and a CO ligand to
form a triphenyltropone species that binds in its enol
form, via the oxygen, to the tungsten atom. The
trimetal species 2, isolated from the simultaneous reac-
tion of [Ni(CO)I(-C
5
Me
5
)], [Mo(CO)
3
(-C
5
H
5
)]
−
and
PhC
2
H, shows the likely fate of the Cp* stripped nickel
atom [4]. The structures of complexes 1 and 2 are given
in Fig. 1.
How complex 1 forms, remains a mystery. Here, we
describe the isolation and structural characterization of
complex 3, a molecule that probably shares a common
intermediate with the methylcyclopentadienyl analog of
1, the
2
-ketone complex 1. We also indicate that 1
(and by inference, 1) as well as the new species 3 require
the presence of nickel to form, even though neither
species contains this element. The C
5
Me
5
ligand trans-
Fig. 1. The structures of complexes 1 and 2.
* Corresponding author. Present address: Laboratoire de Chimie
de Coordination, UMR CNRS 7513, Universite´ Louis Pasteur, 4 rue
Blaise Pascal, 67070 Strasbourg, France. Tel.: +33-390-241316; fax:
+33-390-241322.
E-mail address: chetcuti@chimie.u-strasbg.fr (M.J. Chetcuti).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII:S0022-328X(01)01027-0