An unprecedented example of a cis-phosphonodithioato nickel(ii) complex built by an extensive hydrogen bonding supramolecular network

Article abstract of DOI:10.1039/b200414c

The P-N bond hydrolysis of the 4-methoxyphenyl-ammonium ethylamido-phosphonodithioato ligand during its complexation to Ni^II leads to the first example of phosphonodithioato nickel(II) complex having a cis configuration; this complex is stabili

Full text of DOI:10.1039/b200414c

An unprecedented example of a cis-phosphonodithioato nickel(II
)
complex built by an extensive hydrogen bonding supramolecular
network
Vincenzo G. Albano,a M. Carla Aragoni,b Massimiliano Arca,b Carlo Castellari,a Francesco
Demartin,c Francesco A. Devillanova,b Francesco Isaia,b Vito Lippolis,b Laura Loddob and Gaetano
Verani*b
a Dipartimento di Chimica BG. CiamicianB, Via Selmi 2, I-40126 Bologna, Italy
b Dipartimento di Chimica Inorganica ed Analitica, Cittadella Universitaria, S.S. 554 bivio Sestu, I-09042
Monserrato, CA, Italy. E-mail: verani@unica.it
c
Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Via G. Venezian 21, I-20133 Milano,
Italy
Received (in Cambridge, UK) 11th January 2002, Accepted 14th February 2002
First published as an Advance Article on the web 25th April 2002
The P–N bond hydrolysis of the 4-methoxyphenyl-ammo-
nium ethylamido-phosphonodithioato ligand during its
complexation to NiII leads to the first example of phospho-
nodithioato nickel(II) complex having a cis configuration;
this complex is stabilised in the solid state by an extensive
and intricate network of hydrogen bondings involving the
released ethylenediamine and a water molecule.
(HOpdt)2Ni being the very novel complex cis-bis[(4-methox-
yphenyl) O-hydrogenphosphonodithioato]nickel(II). In cis-
(HOpdt)2Ni (Fig. 1) the nickel ion is coordinated to two HOpdt
anions through the sulfur atoms in a square planar arrangement.
The NiS4 core is strictly planar (deviations from the average
plane 0.04 Å) and the Ni–S distances [average value 2.222(6)
Å] are coincident with those of analogous phosphonodithioato
and amidophosphonodithioato nickel(II) complexes.3 The dis-
tinctive feature of this complex is the cis arrangement of the
4-MeOPh appendages with respect to the coordination plane.
To the best of our knowledge, this is the first case of a
phosphonodithioato complex isolated in the solid state only in a
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 frequently used, coor-
dinative covalent bonds engaged between transition-metal ions
and various organic ‘linkers’, such as 4,4A-bipyridine, propagate
the coordination geometry into infinite architectures of various
dimensionality and topology.1 The other method, still far less
common, exploits 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.2
We present here a very novel case of a ‘one-pot’ self-
assembly of a 3D extended network by a combination of
coordinative and hydrogen bonds.
The reaction between alcohols3,4 and amines3 RAXH (X =
NH, O; RA = alkyl) and diorgano-dithiadiphosphetane dis-
ulfides (RPS2)2 (R = 4-MeOPh, Ph) to give the corresponding
2
phosphonodithioato anions R(RAX)PS2 (RAXpdt), through a
P2S2 ring opening, has recently been described. The subsequent
reaction with Group 10 metal ions gives square-planar phospho-
nodithioato complexes [M(RAXpdt)2] (M = Ni, Pd, Pt) that are
always crystallised as trans-isomers. This is a very simple way
to prepare the phosphonodithioato and amido-phosphonodi-
thioato complexes, whose chemistry had been scarcely explored
because of synthesis difficulties.3 In an attempt [Scheme 1] to
test the reactivity of (RPS2)2 towards bidentate nucleophilic
reagents HXRAXH, we have performed the reaction of Law-
essonAs reagent [R = 4-MeOPh, 1] with ethylenediamine (en).
As expected, the 4-methoxyphenyl-ammoniumethylamido-
phosphonodithioato
inner
salt
[(4-MeOPh)-
(+NH3CH2CH2NH)PS22, 2] was obtained,† and structurally
characterised.‡ Instead of yielding the corresponding trans-
amidophosphonodithioato complex, the reaction of 2 with
NiCl2† results in purple crystals whose X-ray structure
corresponds to the formulation [(HOpdt)2Ni·en·H2O]H (3),‡
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 bond between H(O(3)) and N(1B)
[H…N 2.40 Å], as well as a P(1)…H(N(1B)) contact (2.93 Å) contribute to
bind the units into chains. Interactions a–h couple the chains into ribbons:
a: O(5)…S(4) 3.21, H…S 2.28 Å; b: O(5)…O(3A) 2.81, H(O(5))…O(3A)
1.97 Å; c: P(1A)…O(5) 3.49, P(1A)…H(O(5)) 2.80 Å; d: H(O(3A))…O(5)
2.39 Å; e: O(5)…N(1) 2.94; O(5)…H(N(1)) 2.47 Å; f: C(15A)…S(1) 3.62,
H(C(15A))…S(1) 2.90 Å; g: C(15A)…S(3) 3.62, H(C(15A))…S(3) 2.87 Å; h:
C(16A)…S(1) 3.63, H(C(16A))…S(1) 2.79 Å.
Scheme 1
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This journal is © The Royal Society of Chemistry 2002

cis configuration. Even though the existence of cis-phosphono-
dithioato complexes was demonstrated by Fackler and Thomp-
son,5 who explored the cis–trans isomerisation of the NiII, PdII
and PtII complexes of O-ethylphenylphosphonodithioato
1
[EtO(Ph)PS2]2 anion in several organic solvents by H NMR
spectroscopy, until now these complexes have been known to
crystallise only in a trans configuration. The only other example
of a phosphonodithioato complex in a cis arrangement is
[Au(S2P(OH)Ph)2]Cl, which anyway co-crystallised as a mix-
ture of the cis and trans isomers in a 1+2 ratio.6
It is interesting to note that compound 2 by itself is stable in
the CH3CN–H2O mixture,† and undergoes the hydrolysis of the
P–N bond when reacted with NiCl2, yielding the cis-
(HOpdt)2Ni complex, where a hydroxo group is bonded to the
phosphorus atom instead of the ethylenediamine molecule.
Consequently, the reaction of NiCl2 with 2 completely differs
from those of all other R(RAX)PS22 ligands (X = O, NH; RA =
alkyl), which always give the trans-NiII-complexes in the same
experimental conditions, with the chemical environment of the
phosphorus atom unchanged.3
A further aspect of the chemistry of these complexes is
noteworthy: the trans-[Ni(RAXpdt)2] complexes readily add
nitrogen bases, including ethylenediamine,7 to form green
paramagnetic octahedral adducts.8 In the present case, since the
formation of the cis-(HOpdt)2Ni complex is accompanied by
the release in solution of two ethylenediamine molecules, the
formation of an octahedral nickel(II) complex by addition of en
would be expected. However, not only does en not interact with
the metal centre, but even the addition of an excess of en to the
solution of 3, does not result in any octahedral adduct formation.
In contrast, the mutual recognition between en and the cis-
(HOpdt)2Ni complex occurring at the second coordination
sphere level, leads to the supramolecular assembly [(HOpdt)2-
Ni·en·H2O]H, promoted by the numerous hydrogen bonding
interactions.
Fig. 2 2-D view (bc plane) of [(HOpdt)2Ni·en·H2O]H showing alternate
inorganic/organic interacting layers through H…ring centroid type C–H…p
contacts (3.08 Å, 151°).
engineering of innovative materials based on hydrogen-bonded
networks between co-crystallised transition metal complexes
and organic molecules.
A deeper insight into the reactivity of the new ligand 2 and its
derivatives is currently in progress at our laboratories.
Notes and references
† Syntheses: [(4-MeOPh)(+NH3CH2CH2NH)PS22, 2]: 1 and en were
reacted in CHCl3 at reflux for 10–15 min in different molar ratios (1+2, 1+4,
and a large excess of en); compound 2 was always obtained as the only
product as a white solid, and was recrystallised from a CH3CN–H2O
mixture; found (calc. for C9H15N2OPS2): C, 41.6 (41.2); H, 5.8 (5.8); N,
10.8 (10.7); S, 24.4 (24.4)%. [(HOpdt)2Ni·en·H2O]H: 2 (0.45 g, 1.7 mmol)
was reacted with NiCl2·6H2O (0.23 g, 1.0 mmol) in 40 mL of a CH3CN–
H2O (1+1 v/v) mixture. After refluxing for 10 min the reaction mixture was
allowed to cool at room temperature. The product was quantitatively
obtained as purple crystalline flakes; found (calc. for C16H26N2NiO5P2S4):
C, 33.3 (33.4); H, 4.3 (4.5); N, 4.8 (4.9); S, 22.5 (22.3)%.
The supramolecular structure [(HOpdt)2Ni·en·H2O]H is
made up of discrete molecules of cis-(HOpdt)2Ni, en, and water,
held together by an extended network of hydrogen bonds. Units
of cis-(HOpdt)2Ni are bridged head-to-tail by ethylendiamine
molecules to give infinite 1-D chains running along the c
direction (Fig. 1). The H-bonds between the P–OH moieties and
the N(1)H2 amino groups hold together the infinite chains
[O(3)…N(1) 2.87, O(4)…N(1) 2.67; (N(1))H…O(3) 2.03,
(O(4))H…N(1) 1.81 Å]. Also the aromatic substituents at the
phosphorus atoms, which are disposed on either side of the
chains, bridge adjacent molecules of cis-(HOpdt)2Ni through
CH…p contacts (2.97 Å, 135°, i in Fig. 1).
‡ CCDC reference numbers 178335 and 178336 for 2 and 3, respectively.
See http://www.rsc.org/suppdata/cc/b2/b200414c/
1 A. N. Khlobystov, A. J. Blake, N. R. Champness, D. A. Lemenovskii, A.
G. Majouga, N. V. Zyk and M. Schröder, Coord. Chem. Rev., 2001, 222,
155; S. A. Barnett, A. J. Blake, N. R. Champness, J. E. B. Nicolson and
C. L. Wilson, J. Chem. Soc., Dalton Trans., 2001, 567; L. Carlucci, G.
Ciani, D. M. Proserpio and S. Rizzato, Chem. Commun., 2001, 1198; D.-
L. Long, A. J. Blake, N. R. Champness and M. Schröder, Chem.
Commun., 2000, 2273; L. Carlucci, G. Ciani, D. M. Proserpio and S.
Rizzato, J. Chem. Soc., Dalton Trans., 2000, 3821; D.-L. Long, A. J.
Blake, N. R. Champness and M. Schröder, Chem. Commun., 2000, 1369;
R. Robson, J. Chem. Soc., Dalton Trans., 2000, 3735.
2 S. A. Bourne, J. Lu, B. Moulton and M. J. Zaworotko, Chem. Commun.,
2001, 9, 861; A. J. Blake, P. Hubberstey, U. Suksangpanya and C. L.
Wilson, J. Chem. Soc., Dalton Trans., 2000, 3873; G. R. Desiraju, J.
Chem. Soc., Dalton Trans., 2000, 3745; M. Munakata, L. P. Wu, M.
Yamamoto, T. Kuroda-Sowa and M. Maekawa, J. Am. Chem. Soc., 1996,
118, 3117; M. M. Chowdhry, D. M. P. Mingos, A. J. P. White and D. J.
Williams, Chem. Comm., 1996, 899; C. B. Aakeröy, A. M. Beatty and K.
R. Lorimer, J. Chem. Soc., Dalton Trans., 2000, 3869 and references
therein.
3 M. Arca, A. Cornia, F. A. Devillanova, A. C. Fabretti, F. Isaia, V.
Lippolis and G. Verani, Inorg. Chim. Acta, 1997, 262, 81; M. C. Aragoni,
M. Arca, F. Demartin, F. A. Devillanova, C. Graiff, F. Isaia, V. Lippolis,
A. Tiripicchio and G. Verani, Eur. J. Inorg. Chem., 2000, 2239 and
references therein; M. C. Aragoni, M. Arca, F. A. Devillanova, J. Ferraro,
V. Lippolis and G. Verani, Can. J. Chem., 2001, 79, 1483.
4 W. E. Van Zyl and J. P. Fackler, Phosphorus, Sulfur Silicon Relat. Elem.,
2000, 167, 117.
Pairs of infinite symmetry-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 S(4) atom of one
chain [O(5)…S(4) 3.21, H…S 2.28 Å, a] with the opposite
O(3A) atom [O(3)…O(5) 2.81, (O(5))H…O(3A) 1.97 Å, b].
Other secondary bonds and contacts are described in Fig. 1.
The ribbons are interpenetrated by interacting through
H…ring centroid type C–H…p contacts (3.08 Å, 151°),9
forming 2-D 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 N(2)H2 amino group and the O(3)
and O(5) atoms of neighbouring sheets [N(2)…O(3) 2.73;
N(2)…O(5) 2.80; (N(2))H…O(3)/(5) 1.92/1.96 Å].
We believe this to represent the first example of a one-pot self
assembly of a transition metal complex-organo network, where
both building blocks [en and cis-(HOpdt)2Ni] are formed in situ
from a single starting material (2). Actually, the supramolecular
crystallisation process seems to be, in our opinion, the driving
force for the unusual hydrolytic P–N bond cleavage, the
subsequent releasing of en, and the generation of cis-
(HOpdt)2Ni.
5 J. P. Fackler Jr. and L. D. Thompson Jr., Inorg. Chim. Acta, 1981, 48,
45.
6 H. H. Murray, G. Garzon, R. G. Raptis, A. M. Mazany, L. C. Porter and
J. P. Fackler Jr., Inorg. Chem., 1988, 27, 836.
7 M. C. Aragoni, M. Arca, F. A. Devillanova, F. Isaia, V. Lippolis and G.
Verani, work in progress.
8 M. C. Aragoni, M. Arca, F. Demartin, F. A. Devillanova, C. Graiff, F.
Isaia, V. Lippolis, A. Tiripicchio and G. Verani, J. Chem. Soc., Dalton
Trans., 2001, 2671 and references therein.
The possibility of incorporating metal ions into extended
hydrogen-bonded arrays using a single starting material could
represent a brand new one-pot synthetic route to the crystal
9 T. Steiner, E. B. Starikov and M. Tamm, J. Chem. Soc., Perkin Trans. 2,
1996, 67.
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