Complexes of 1,3-Bis(diphenylphosphano)propane (dppp) with Dichloroplatinum(II) and Bis(chlorogold(I))
Fig. 4 Coordination alternatives of 1,3-bis(diphenylphosphino-
propane) (μ-dppp), P ϭ PPh
Fig. 3 Bond angles at the AuϪAu junction in
cyclo-[(μ-dppp)(AuCl) ].
2
.
2
AuϪAu distance strongly depends on the quality of the
basis set and on a proper treatment of the Au environment.
Initial DFT calculations of a model system with the phenyl
groups of dppp replaced by methyl groups and a triple ξ
basis with frozen core approximation did not converge at
dichloromethane. The resulting precipitate was washed with
hexane, recrystallized from CH Cl /hexane (1/3) and dried under
vacuum to yield 680 mg (58 %). Diffusion of hexane into a satu-
rated solution in dichloromethane produced single crystals suitable
2
2
for diffraction. C27
.01 (2.99); Au 45.39 % (44.90 %). H-NMR (CD
(m, 2H), 2.65-2.85 (m, 4H), 7.44-7.73 (m, 20H).
2 2 2
H26Au Cl P (877.25): C 36.75 (ber. 36.97); H
1
3
2 2
Cl ): 1.87-1.98
all to the cyclic structure. Too long AuϪAu distances
˚
(
> 3.4 A) were obtained when the calculations were carried
out for the real complex using the frozen core approxi-
mation or when ADF/QZ4P calculations were applied to
the model system.
2
The ground state electronic structure of [(μ-dppp)(AuCl )] was cal-
culated by density functional theory (DFT) methods using the
ADF2004.1 [12, 13] program package. Two types of basis sets were
used for the calculations: (i) Slater type orbital (STO) basis sets of
triple ζ quality with two polarization functions (TZ2P) and the
inner shells represented by a frozen core approximation (1s for C,
1s-2p for P and 1s-4d for Au were kept frozen),and (ii) STO basis
sets of quadruple ζ quality with four polarization functions (QZ4P)
including core electrons. These basis sets were employed with the
exception of the phenyl substituents on the P atoms which were
described by a double ζ basis. The following density functionals
were used: A local density approximation (LDA) with VWN para-
metrization of electron gas data and a functional including Becke’s
gradient correction to the local exchange expression in conjunction
with Perdew’s gradient correction to the LDA expression (BP) [14].
The scalar relativistic (SR) zero order regular approximation
(ZORA) was used within this study.
Table 3 shows, however, that the ADF/QZ4P calculated
bond lengths and angles for the real system reasonably rep-
resent the main features of the experimental structure once
the inner shells are included. Even so, the calculation over-
estimates the AuϪAu distance while the other bond lengths
˚
are reproduced within several hundreds of A.
Characteristically, the calculated angles AuϪAuϪP and
AuϪAuϪCl are quite different between the two sites as in
the experiment. Specifically, there is an almost ideal T shape
realized for the Au(PAuCl) coordination environment at
Au2 whereas Au1 adopts a more distorted structure
(Fig. 3), probably a consequence of ring strain.
However, both gold atoms display a sum of angles
Σ > 358°, confirming an almost planar arrangement at each
metal center.
As shown here, the attachment of potentially oligofunc-
tional metal atoms to a simple diphosphane ligand can lead
to a variety of cyclo or catena coordination complexes
The X-ray data of the crystals obtained as described above were
collected at 173(2) K on a Siemens P4 diffractometer, using graph-
ite monochromated Mo-Kα radiation (λ ϭ 0.71073 A) and em-
˚
ploying Wyckoff scans. Further details are given in Table 1. All
structures were solved by the Patterson method using the
SHELXTL package while refinement was carried out with
(Fig. 4), the interconversion of such polymorphs will thus
be an attractive next area to investigate.
2
SHELXL97 employing full-matrix least-squares methods on F
2
2
It is also remarkable that less extensive calculations did
not well reproduce this structure, indicating the very high
quality approach necessary to theoretically access the
with F0 Ն Ϫ2σ(F ) [15]. The Flack parameter [16] for the crystal
0
of the gold compound is 0.009(13). All non-hydrogen atoms were
refined anisotropically, hydrogen atoms were introduced using
appropriate riding models. Empirical absorption correction was
performed using Ψ-scans.
I
I
Au ϪAu bonding interaction [3].
Experimental
Crystallographic data have been deposited with the Cambridge
Crystallographic Data Centre, CCDC-266333 and 266334. Copies
of the information may be obtained free of charge from: The Direc-
tor, CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax:
www.ccdc.cam.ac.uk).
NMR spectra were taken on a Bruker AC 250 spectrometer.
Complex [(dppp)PtCl
2
] was obtained according to the literature
1
10] in 70 % yield and was characterized by H- and 31P-NMR spec-
[
troscopy.
cyclo-[(μ-dppp)(AuCl)
2
] was obtained by reacting 1.0 g (2.64 mmol)
This work was supported by the Deutsche Forschungsgemein-
schaft, the European Union (COST D14 Action) and the Fonds
KAuCl
4
and 1.1 g (2.64 mmol) dppp for 3 hours in 25 ml refluxing
Z. Anorg. Allg. Chem. 2005, 631, 1355Ϫ1358
zaac.wiley-vch.de
© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim
1357
Kaim, Wolfgang
