Journal of Organometallic Chemistry 637 – 639 (2001) 126 – 133
www.elsevier.com/locate/jorganchem
1,1,2,2-Tetrakis(diphenylphosphino)-4,4-di-tert -butylferrocene, a
new cisoid arrangement of phosphino groups
Roland Broussier
a
, Emmanuelle Bentabet
a
, Re ´gine Amardeil
a
, Philippe Richard
a
,
Philippe Meunier
a,
*, Philippe Kalck
b
, Bernard Gautheron
a
a
Laboratoire de Synthe `se et d’Electrosynthe `se Organome ´talliques (UMR 5632), Uniersite ´ de Bourgogne, 6, bouleard Gabriel,
21000 Dijon, France
b
Laboratoire de Catalyse, Chimie fine et Polyme `res, Ecole Nationale Supe ´rieure de Chimie de Toulouse, 118, route de Narbonne,
31077 Toulouse Cedex, France
Received 12 January 2001; received in revised form 15 March 2001; accepted 26 March 2001
Abstract
The action of two equivalents of 1,2-bis(diphenylphosphino)-4-tert -butylcyclopentadienyllithium on FeCl
2
led to the corre-
sponding 1,1,2,2-tetraphosphinoferrocene. The X-ray structure of this bulky ferrocene is described. The spectroscopic results
reveal a conformational chirality with a cisoid disposition of the phosphino groups. The first results about the complexation with
representative elements of Group IX and X (Rh, Pd, Ir) are reported. © 2001 Elsevier Science B.V. All rights reserved.
Keywords: Phosphinoferrocene; Group IX and X complexes; Cisoid ; Arrangement
1. Introduction
In the field of the ferrocene derivatives and their
coordination chemistry, di or polyphosphines, as the
dppf, are powerful auxiliaries [1]. Several types of di or
polyphosphines can be imagined [2] with different sub-
stitution patterns on Cp rings and various steric and
electronic properties. We have been interested in the
1,2-disubstitution and original representative examples
of this class have been synthesized and studied: 1,2-bis(-
diphenylphosphino)-3,4,5-trimethylferrocene [3] and
1,2-bis(diphenylphosphino)-4-tert -butylferrocene [4].
These ferrocenes were obtained from a mixture of the
corresponding substituted and unsubstituted cyclopen-
tadienyl lithium salts and FeCl
2
. Using this approach
and exclusively 1,2-bis(diphenylphosphino)cyclo-
pentadienyl salts, a tetraphosphine of 1,2 and 1,2
substitution pattern was expected. Only two ferro-
cenyltetraphosphines are available: the 1,1,2,2-tetrak-
is(diphenylphosphino)ferrocene recently reported by
Butler et al. [2] and its hexamethyl analogue [3]. The
availability of phosphorus atoms and their coordina-
tion capacities are in part directed by the backbone
rigidity of the ligand as shown in the following
polyphosphines. Structurally characterized examples of
two biligate coordination modes are reported for
branched tetradentate phosphines as 2,3-bis[(di-
phenylphosphino)methyl] - 1,4 - bis(diphenylphosphino)-
butane [5], 1,2,4,5-tetrakis[(diphenylphosphino)methyl]
or [diphenyl-phosphino]benzene [6] and cis,trans,cis -
1,2,3,4-tetrakis(diphenylphosphino)cyclobutane [7]. The
linear tetradentate Ph
2
PCH
2
CH
2
P(Ph)CH
2
CH
2
P-
(Ph)CH
2
CH
2
PPh
2
[8] or MeHP(CH
2
)
3
P(Me)(CH
2
)
2
P-
(Me)(CH
2
)
3
PMeH [9] and the tripodal tetradentate
P(CH
2
CH
2
PPh
2
)
3
[10], P(o -C
6
H
4
PPh
2
)
3
[11] or
P(CH
2
CH
2
CH
2
PMe
2
)
3
[12] are tetracoordinated to the
metal center. The specific geometry of ferrocene and the
independance of the two Cp rings can make a te-
traphosphine equivalent to two diphosphines or allow a
higher coordination number due to the rings rotation.
At this time, the highlighted behavior are of type
1,2-diphosphine for 1,1,2,2 tetraphosphine [3] and of
type 1,2 or 1,1 for the 1,2,1 triphosphine [13]. In this
paper, we report a new example of ferrocenic tetraphos-
phine as well as its behavior towards Pd, Rh and Ir
salts leading to various coordination modes.
* Corresponding author. Fax: +33-3-8039-6100.
E-mail address: philippe.meunier@u-bourgogne.fr (P. Meunier).
0022-328X/01/$ - see front matter © 2001 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(01)00883-X