metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
there is a slight but signi®cant distortion from planarity
towards tetrahedral, and both bond angles at Pd involving
trans pairs of substituents are less than 175ꢀ (Table 1). The
Ê
ISSN 0108-2701
deviations (A) of the ligating atoms from their best plane
through Pd are: Cl 0.106 (1), S 0.105 (1), P1 0.105 (1) and
trans-Chloro(2-nitrobenzenethiol-
ato-S)bis(triphenylphosphine-P)-
palladium(II) monoacetone solvate
John H. Aupers,a George Ferguson,b² Christopher
Glidewell,c* John N. Lowc and James L. Wardelld
P2 0.106 (1). In this respect, the con®guration of the trans-
PdClP2S chromophore in (I) differs from those found in two
analogous compounds retrieved from the Cambridge Struc-
tural Database (Allen & Kennard, 1993) containing trans-
PdCl2P2 and trans-PdP2S2 chromophores. Molecules of trans-
[PdCl2(PPh3)2] are centrosymmetric both in the unsolvated
compound (BISKIX; Ferguson et al., 1982) and in the bis-
chloroform solvate (RAVYUI; Stark & Whitmire, 1997).
Similarly, molecules of trans-[Pd{PH(C6H11)2}2(SPh)2] (LET-
NON; Pasquali et al., 1993) lie across inversion centres. Hence,
in all these complexes, palladium and its four ligating atoms
are strictly coplanar.
The conformation of (I) is close to that expected (Low,
Storey et al., 2000) for the global energy minimum. There is a
slight rotation around the CÐS bond away from coplanarity of
the Pd atom with the nitrated aryl ring, and a disrotatory twist
of the nitro group around the CÐN bond. The dihedral angles
between the nitrated aryl ring and the planes de®ned by C1Ð
S1ÐPd1ÐCl1 and C6±NO2 are 6.2 (2) and 16.3 (2)ꢀ, respec-
tively. In centrosymmetric molecules of trans-[PdCl2(PPh3)2]
(Ferguson et al., 1982; Stark & Whitmire, 1997), the PÐC
bonds of the two phosphine ligands are necessarily exactly
staggered. In contrast, in (I), these PÐC bonds are almost
eclipsed, with a mean deviation of 5.9 (3)ꢀ from a fully eclipsed
Ph3PÐPdÐPPh3 fragment. Presumably, the rotational
barriers about the PdÐP bonds are low.
aRose Cottage, Middle Assendon, Henley-on-Thames, Oxon RG9 6AU, England,
bSchool of Chemistry, University of St Andrews, St Andrews, Fife KY16 9ST,
Scotland, cDepartment of Applied Physics and Electronic & Mechanical Engineering,
University of Dundee, Nethergate, Dundee DD1 4HN, Scotland, and dDepartment of
Chemistry, University of Aberdeen, University of Aberdeen, Meston Walk, Old
Aberdeen AB24 3UE, Scotland
Correspondence e-mail: cg@st-andrews.ac.uk
Received 4 May 2000
Accepted 15 May 2000
Molecules of the title compound, [PdCl(C6H4NO2S)(PPh3)2]Á-
C3H6O, exhibit a slight distortion from exact planarity at the
Pd atom towards tetrahedral, with PÐPdÐP and ClÐPdÐS
angles of 174.98 (3) and 174.19 (3)ꢀ, respectively. The PdÐCl
and PdÐS bonds are, respectively, long [2.3550 (11) A] and
Ê
short [2.3020 (12) A] for their types; the SÐC bond is also
Ê
very short [1.744 (4) A]. The solvating acetone molecule is
linked to one of the phosphine ligands by means of a CÐ
HÁ Á ÁO hydrogen bond.
Ê
Comment
We have recently reported the structures of members of the
2-O2NC6H4SX system containing the 2-nitrobenzenethiolate
group, in which the ꢀ-atom of fragment X can be C or N (Low,
Storey et al., 2000) or S (Low, Glidewell & Wardell, 2000). In
general, at the global energy minimum conformation, both the
nitro group and the ꢀ-atom of group X are essentially
coplanar with the aryl ring. When X is not in the plane of the
aryl ring, rotation about the exocyclic CÐS bond is associated
with a disrotatory twist of the nitro group about the CÐN
bond; the occurrence of such conformations seems to depend
on the presence in the structure of speci®c intermolecular
interactions, such as CÐHÁ Á ÁO hydrogen bonds. Seeking to
investigate the wider generality of this idea, we report here the
structure of a further compound of type 2-O2NC6H4SX,
namely trans-chloro(2-nitrobenzenethiolato-S)bis(triphenyl-
phosphine-P)palladium(II), in which the ꢀ-atom of group X is
Pd and which crystallizes from acetone as a 1:1 solvate, (I).
Molecules of the Pd complex (I) lie in general positions
(Fig. 1). Although no bond angle at Pd involving a pair of cis
substituents deviates from 90ꢀ by more than 1.7ꢀ, nonetheless
The two independent PdÐP distances in (I) (Table 1) are
Ê
both very similar to those reported for BISKIX [2.337 (2) A]
Ê
and RAVYUI [2.343 (2) A]. However, the PdÐCl distance in
(I) is very much longer than the corresponding distances in
Ê
Ê
BISKIX [2.291 (2) A] and RAVYUI [2.293 (2) A]. On the
other hand, the PdÐS distance in (I) is much shorter than
Ê
those reported for LETNON [2.3393 (16) and 2.3366 (19) A in
two independent molecules]. These observations can all be
readily rationalized in terms of the trans in¯uence, t(X), of a
ligand X upon the properties of the metal±ligand bond trans to
X, which arises from the competition for a common metal d
orbital of the ꢁ type between ligands occupying trans sites.
Ligands of high trans-in¯uence render the metal±ligand bonds
trans to themselves longer (Appleton et al., 1973), and ligands
can thus be ranked in order of t(X). This is a static thermo-
dynamic phenomenon which closely parallels the dynamic
kinetic trans effect describing the in¯uence on the rates of
ligand substitution exerted by ligands in trans sites (Basolo &
² GF was on leave from the Department of Chemistry and Biochemistry,
University of Guelph, Guelph, Ontario, Canada N1G 2W1.
ꢁ
Acta Cryst. (2000). C56, 945±947
# 2000 International Union of Crystallography
Printed in Great Britain ± all rights reserved 945
Aupers, John H.
