An unusual cis-phosphonodithioato Pd(II) complex in an extensive hydrogen bonding 3D network

Article abstract of DOI:10.1016/j.ica.2004.07.019

The one-pot self-assembly of an extended network of hydrogen bondings involving a cis-Pd-phosphonodithioato complex, ethylenediamine and water is presented. The P-N bond hydrolysis of the 4-methoxyphenyl-ammoniumethylamido- phosphonodithioato ligand on complexation to Pd^II leads to the first example of a Pd-phosphonodithioato complex in a cis configuration, stabilised in the solid state by an extended network of hydrogen bondings involving the released ethylenediamine and a water molecule.

Full text of DOI:10.1016/j.ica.2004.07.019

Inorganica Chimica Acta 358 (2005) 213–216
www.elsevier.com/locate/ica
Note
An unusual cis-phosphonodithioato Pd(II) complex in an
extensive hydrogen bonding 3D network
a,
a
b
Maria Carla Aragoni *, Massimiliano Arca , Francesco Demartin ,
a
Francesco A. Devillanova , Francesco Isaia , Vito Lippolis , Gaetano Verani
a
a
a
a
´
Dipartimento di Chimica Inorganica ed Analitica, Universita degli Studi di Cagliari, Cittadella Universitaria di Monserrato,
S.S. 554 bivio Sestu, 09042 Monserrato (Cagliari), Italy
Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Via G. Venezian 21, 20133 Milano, Italy
b
Received 12 May 2004; accepted 10 July 2004
Available online 12 August 2004
Abstract
The P–N bond hydrolysis of the 4-methoxyphenyl-ammoniumethylamido-phosphonodithioato ligand on complexation to PdII
leads to the first example of a Pd-phosphonodithioato complex in a cis configuration, stabilised in the solid state by an extended
network of hydrogen bondings involving the released ethylenediamine and a water molecule.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Supramolecular chemistry; Phosphonodithioato ligands; Pd; X-ray crystal structure
1. Introduction
tion of metal ions into extended networks gives access
to a variety of physical properties [4] such as optical
properties, electrical conductivity and magnetism [5].
Existing design strategies for the synthesis of extended
inorganic networks follow two principal methods based
on the different nature of the interactions responsible for
networking. In one approach, which is the more fre-
quently used, coordinative covalent bonds engaged be-
tween transition-metal ions and various organic
‘‘linkers’’, such as 4,40-bipyridine, propagate the coordi-
nation geometry into infinite architectures of various
dimensionality and topology [6]. The other method ex-
ploits weaker intermolecular forces (particularly p–p
interactions, hydrogen bonding, and halogen bonding)
as a guide to the assembly of molecular coordination
complexes into extended networks [7]. We present here
an innovative approach based on the ‘‘one-pot’’ self-as-
sembly of a 3D extended network by a combination of
coordinative and hydrogen bonds, starting from a lig-
and formed in situ by P–N bond hydrolysis during the
reaction with the metal ion.
After 30 years of its origin [1], crystal engineering is a
research field at the best of its blossoming, and it is
attracting an increasing number of scientists on the
international scene. In fact, due to the contributions
deriving from every branch of chemistry, modern crystal
engineering embraces now traditionally separated disci-
plines such as organic, inorganic and organometallic
synthetic chemistry, as well as theoretical and physical
chemistry, and materials science. The crystal engineering
philosophy is that of utilising non-covalent interactions
and/or coordination bonds to generate supramolecular
structures, which respond to predetermined features
[2]. Inorganic supramolecular chemistry has now be-
come a rapidly expanding area [3], since the incorpora-
*
Corresponding author. Tel.: +39 070 675 4491; fax: +39 070 675
4456.
E-mail address: aragoni@unica.it (M. Carla Aragoni).
0020-1693/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2004.07.019

214
M. Carla Aragoni et al. / Inorganica Chimica Acta 358 (2005) 213–216
2. Experimental
ture model riding on their pertinent atoms; those of the
water molecule were instead refined with constraints.
2.1. Materials and methods
2.4. Crystal data for 3
All solvents and Lawessonꢀs Reagent (1) are commer-
cially available and were used as received. Elemental
analyses were performed with an EA-1108 CHNS-O Fi-
sons instrument. Infrared spectra were recorded with a
Bruker IFS55 Spectrometer at room temperature.
NMR spectra were recorded with a Varian Unity Inova
400-MHz instrument. 31P NMR chemical sifts were cal-
ibrated indirectly through the 85% H3PO4 peak
(d = 0.0).
C16H26N2O5P2PdS4, M = 622.97, monoclinic, space
˚
group Pc, a = 7.080(2), b = 16.250(3), c = 10.719(3) A,
3
˚
b = 95.39(2)°, U = 1227.8(5) A , Z = 2, Dc = 1.685
g cmꢀ3, l(Mo Ka) = 1.256 mmꢀ1, 2370 reflections col-
lected, 2128 unique, R = 0.0173, wR2 = 0.0431 [2036
reflections having I>2r(I)]. Crystallographic data
(excluding structure factors) have been deposited with
the Cambridge Crystallographic Data Centre, CCDC
No. 246270. Copies of the data can be obtained free
of charge on application to The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: int. Code
+1223-336-033; e-mail, deposit@ccdc.cam.ac.uk).
2.2. Synthesis
[(4-MeOPh)(+NH3CH2CH2NH)PS2ꢀ] (2) was syn-
thesised by reacting 1 and ethylenediamine (en) accord-
ing to a procedure previously outlined [8]. 3 was
synthesised by reacting 2 (0.52 g, 2.0 mmol) with
K2PdCl4 (0.33 g, 1.0 mmol) in 70 mL of a CH3CN:H2O
1:1 mixture. After refluxing for 1 h, the reaction mix-
ture was cooled to room temperature and the orange
crystalline product was filtered off. Yield 0.32 g
(51.4%). Elemental Anal. Calc./found: for C16H26-
N2O5P2PdS4: C, 31.2 (30.8); H, 4.0 (4.2); N, 4.7 (4.5);
S, 20.8 (20.6)%. IR: 2056 s(br), 1630 m, 1601 vs, 1568
s, 1502 vs(br), 1456 ms, 1437 m, 1405 m, 1344 mw,
1309 m, 1297 ms, 1266 s, 1254 ms, 1179 s, 1118 s,
1085 s, 1071 s, 1022 vs(br), 823 vs, 800 ms, 718 w,
650 ms, 633 mw, 590 s, 551 s, 520 m, 412 mw, 404
3. Results and discussion
The reaction between diorgano-dithiadiphosphetane
disulfides (RPS2)2 (R = 4-MeOPh, Ph) and alcohols
[13,14] or amines [13] R0XH (X = NH, O; R = alkyl)
has recently been described.
R
S
S
S
S
R
S
S
P
P
P
R
R'X
(RPS2)2
R'Xpdt
mw, 371 w, 329 w, 313 w, 300 w cmꢀ1 1H NMR
.
The resulting phosphonodithioato anions R(R0X)-
(DMSO solution): d = 8.55 (br), 8.15 (m), 7.75 (m),
7.10 (d), 6.99 (d), 3.92 (m), 3.88 (m), 3.22 (s), 2.62 (s)
ppm. 31P NMR (CDCl3 solution): d = 74.5, 75.6 ppm.
ꢀ
PS2 (R0Xpdt) react with Group 10 metal ions giving
square-planar phosphonodithioato complexes [M(R0-
Xpdt)2] (M = Ni, Pd, Pt) that generally crystallize as
trans-isomers. Recently, from the reaction between
Lawessonꢀs reagent [R = 4-MeOPh, 1] and ethylenedi-
amine (en) the expected amidophosphonodithioato
anion was obtained as inner salt [(4-MeOPh)(+NH3-
CH2CH2NH)PS2ꢀ, 2] featuring the proton on the amino
group not bound to the phosphorous atom [8].
2.3. X-ray crystallographic studies
Crystals of 3 were obtained by slowly cooling a solu-
tion of 3 in CH3CN/H2O 1:1 mixture. A crystal sample
was mounted on glass fibre in a random orientation
and collected at room temperature on an Enraf-Nonius
CAD4 diffractometer. Graphite monochromatised Mo
Reaction of 2 with K2PdCl4 affords crystals of
[(HOpdt)2Pd Æ en Æ H2O] (3), whose crystal structure is
˚
Ka radiation (k = 0.71073 A) was used with the genera-
1
made up of discrete molecules of cis[(HOpdt)2Pd], en,
and water, held together by an extended network of
hydrogen bonds. The unusual complex cis-bis[(4-meth-
oxyphenyl)-hydroxyl-phosphonodithioato]Pd (Fig. 1)
contains a palladium ion coordinated to two HOpdt ani-
ons through the sulfur atoms in a square-planar arrange-
tor working at 50 kV and 30 mA. Cell parameters and
orientation matrix were obtained from least-squares
refinement on 25 reflections measured in the range
9.40 < h < 15.42°. Three reference reflections were recol-
lected to have a monitoring of the crystal decay, which
was not observed. An absorption correction was applied
using the w-scan routine [9]. The structure was solved by
direct methods (SIR 97) [10] and refined on F2 using the
SHELX-97 [11] program implemented in the WINGX suite
[12]. Anisotropic displacement parameters were assigned
to all non-hydrogen atoms. The hydrogen atoms, all seen
in a difference Fourier map, were included in the struc-
˚
ment, with an average Pd–S distance of 2.339 A. The
HOpdt anions are formed in situ by hydrolytic cleavage
of the P–N bond of 2 and substitution of the en moiety
with a hydroxyl group. The PdS4 core is essentially pla-
nar with maximum deviations from the average plane
˚
of 0.05 A. The distinctive feature of this complex is the

M. Carla Aragoni et al. / Inorganica Chimica Acta 358 (2005) 213–216
215
PtII complexes of O-ethyl-phenylphosphonodithioato
1
[EtO(Ph)PS2]ꢀ anion in several organic solvents by H
NMR spectroscopy, these complexes commonly crystal-
lise only in a trans configuration. To the best of our
knowledge, the other unique case of phosphonodithioato
complex isolated in the solid state only in a cis configura-
tion is cis-bis[(4-methoxyphenyl)-hydroxyl-phosphono-
dithioato]Ni, recently reported [8], which is
isostructural with compound 3. Although C2v, Cs and
C2 symmetries are accessible to the cis-isomer, the mole-
cule adopts an asymmetric conformation in the crystal.
While the P2 atom lies approximately in the coordination
˚
plane [distance 0.108(1) A], P1 is significantly displaced
˚
on the side of its phenyl ring [distance 0.465(1) A]. In
addition, the phenyl ring is oriented to be almost copla-
nar with the O3–P1–C8 plane [dihedral angle 12.3°]. The
simultaneous occurrence of these two features suggests
that they co-operate in optimising the Pdꢁ ꢁ ꢁH(C9) con-
˚
tact [3.20 A] in order to establish a weak agostic-type
interaction. At the same time, the hydrogen bonded to
C13 is engaged in the O3ꢁ ꢁ ꢁH(C13) contact that adds sta-
bility and helps in maintaining the most favourable ori-
entation of the phenyl group. An analysis of the
conformation of the phenyl ring bonded to P2 also re-
veals a special orientation, being the phenyl almost
coplanar with the S3P2C1 plane [dihedral angle 6.4°].
This orientation minimises the S3ꢁ ꢁ ꢁH(C6) contact
Fig. 1. Herringbone-like ribbons formed by coupled chains built by
propagating 3 along the c direction. Besides the hydrogen bonds
described in the text, a secondary weak hydrogen 0b0 ond between N2
˚
[2.83 A], which corresponds to an attractive sulfur–hy-
drogen interaction.
0
˚
˚
and H(O3 ) [Hꢁ ꢁ ꢁN 2.40 A], as well as a P1ꢁ ꢁ ꢁH(N1 ) contact (2.93 A)
Units of [(HOpdt)2Pd] are bridged head to tail by
ethylenediamine molecules to give infinite 1D chains
running along the c direction (Fig. 1). The H-bonds be-
tween the P–OH moieties and the N1H2 amino groups
hold together the infinite chains [O30ꢁ ꢁ ꢁN1 2.877(5),
O4ꢁ ꢁ ꢁN1 2.667(6); (N1)Hꢁ ꢁ ꢁO30 2.00(6), (O4)Hꢁ ꢁ ꢁN1
contribute to bind the units into chains. Non-interacting hydrogen
0
atoms and N2 atoms have been omitted for clarity. : x, y, ꢀ1 + z; 00: x,
y, 1 + z; 000: x, 1ꢀy, ꢀ1/2 + z.
cis arrangement of the 4-MeOPh appendages with re-
spect to the coordination plane. In fact, even though
the existence of cis-phosphonodithioato complexes was
demonstrated by Fackler and Thompson [15], who ex-
plored the cis–trans isomerisation of the NiII, PdII, and
˚
1.85(6) A]. Also the aromatic substituents at the phos-
phorus atoms, which are disposed on either side of the
chains, bridge adjacent molecules of [(HOpdt)2Pd]
Fig. 2. 2D view (bc plane) of [(HOpdt)2Pd Æ en Æ H2O] showing alternate inorganic (shaded) and organic (clear) layers interacting through Hꢁ ꢁ ꢁring
1
˚
centroid type C–Hꢁ ꢁ ꢁp contacts (2.96 A). Non-interacting hydrogen atoms have been omitted for clarity.

216
M. Carla Aragoni et al. / Inorganica Chimica Acta 358 (2005) 213–216
˚
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1375.
through CHꢁ ꢁ ꢁp contacts (2.96 A). Pairs of infinite sym-
metry-related chains arranged on parallel planes shifted
by c/2 are coupled together into infinite herringbone-like
ribbons. The water molecules play the main role in
forming these ribbons by H-bonding the S4 atom of
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3177;
˚
one chain [O5ꢁ ꢁ ꢁS4 3.204(4), Hꢁ ꢁ ꢁS 2.40 A, a] with the
opposite O3000 atom [O3000ꢁ ꢁ ꢁO5 2.839(5), (O5)Hꢁ ꢁ ꢁO3000
˚
1.97 A, b]. The ribbons are interpenetrated by interact-
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2983.
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[16] forming 2D sheets (bc planes) as shown in Fig. 2.
These sheets pack on top of each other along the axis
a by interacting through hydrogen bonds, involving
the N2H2 amino group and the O3 and O5 atoms of
neighbouring sheets [N2ꢁ ꢁ ꢁO3 2.764(5); N2ꢁ ꢁ ꢁO5
[6] (a) A.N. Khlobystov, A.J. Blake, N.R. Champness, D.A. Lem-
enovskii, A.G. Majouga, N.V. Zyk, M. Schro¨der, Coord. Chem.
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˚
2.800(6); N2Hꢁ ꢁ ꢁO3/O5 1.95/1.92 A].
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4. Conclusions
(b) A.J. Blake, P. Hubberstey, U. Suksangpanya, C. Wilson, J.
Chem. Soc., Dalton Trans. (2000) 3873;
In conclusion, the mutual recognition between
cis[(HOpdt)2M] complexes (M = Ni [8], Pd (3)) and
ethylenediamine occurs at the second coordination
sphere level, leading to the supramolecular assembly
(c) G.R. Desiraju, J. Chem. Soc., Dalton Trans. (2000) 3745;
(d) C.B. Aakero¨y, A.M. Beatty, K.R. Lorimer, J. Chem. Soc.,
Dalton Trans. (2000) 3869 and references therein.
[8] V.G. Albano, M.C. Aragoni, M. Arca, C. Castellari, F. Demartin,
F.A. Devillanova, F. Isaia, V. Lippolis, L. Loddo, G. Verani,
Chem. Commun. (2002) 1170.
[(HOpdt)2M Æ en Æ H2O] , promoted by the hydrogen
1
bonding interactions. The crystallisation process seems
to be the driving force for the unusual hydrolytic P–N
bond cleavage with successive release of en and forma-
tion of the cis[(HOpdt)2M] complex. The possibility of
incorporating different metal ions into extended hydro-
gen-bonded network starting from a single material rep-
resents a novel one-pot synthetic route to the crystal
engineering of supramolecular materials based on
hydrogen-bondings involving coordination compounds
and organic molecules.
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Appendix A. Supplementary material
(c) M.C. Aragoni, M. Arca, F.A. Devillanova, J. Ferraro, V.
Lippolis, G. Verani, Can. J. Chem 79 (2001) 1483;
(d) M.C. Aragoni, M. Arca, N.R. Champness, A.V. Cher-
nikov, F.A. Devillanova, F. Isaia, V. Lippolis, N.S. Oxtoby,
G. Verani, S.Z. Vatsadze, C. Wilson, Eur. J. Inorg. Chem.
10 (2004) 2008.
Supplementary data associated with this article can
be found, in the online version at doi:10.1016/
j.ica.2004.07.019.
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