Zwitterionic metalates of group 11 elements and their use as metalloligands for the assembly of multizwitterionic clusters

Article abstract of DOI:10.1021/ja0554110

Reaction of RNHC(S)PPh₂NPPh₂C(S)NR (HRSNS; R = Me, Et) with M^I (M = Cu, Ag, Au) salts afforded zwitterionic complexes of the general formula [M(RSNS)] (M = Cu, Ag, Au). The ligand was found in the solid state in S,S-κ² and S,N,S-κ³ coordination fashions. [Cu(RSNS)] and [Ag(RSNS)] can be used as metalloligand building blocks for the assembly of pentanuclear multizwitterionic Cu ₅, Cu₃Ag₂ and Ag₅ core clusters of the general formula [M′₂{M(RSNS)}₃]²⁺ (M = Cu, M′ = Cu, Ag; M = M′ = Ag) upon reaction with suitable M′ salts. The crystal structures of the most significant compounds are reported herein. Compound [Ag₂{Ag(RSNS)}₂(OTf)₂] was also isolated and structurally characterized, representing a model for the intermediate species of the aforementioned assembly.

Full text of DOI:10.1021/ja0554110

Published on Web 12/24/2005
Zwitterionic Metalates of Group 11 Elements and Their Use as
Metalloligands for the Assembly of Multizwitterionic Clusters
Roberto Pattacini, Lorenzo Barbieri, Alessandro Stercoli, Daniele Cauzzi,*
Claudia Graiff, Maurizio Lanfranchi, Antonio Tiripicchio, and Lisa Elviri
Contribution from the Dipartimento di Chimica Generale ed Inorganica, Chimica Analitica,
Chimica Fisica, UniVersita` di Parma, Parco Area delle Scienze 17/A, I-43100 Parma, Italy
Received August 17, 2005; E-mail: cauzzi@unipr.it
Abstract: Reaction of RNHC(S)PPh2NPPh2C(S)NR (HRSNS; R ) Me, Et) with MI (M ) Cu, Ag, Au) salts
afforded zwitterionic complexes of the general formula [M(RSNS)] (M ) Cu, Ag, Au). The ligand was found
in the solid state in S,S-κ2 and S,N,S-κ3 coordination fashions. [Cu(RSNS)] and [Ag(RSNS)] can be used
as metalloligand building blocks for the assembly of pentanuclear multizwitterionic Cu5, Cu3Ag2 and Ag5
core clusters of the general formula [M′2{M(RSNS)}3]2+ (M ) Cu, M′ ) Cu, Ag; M ) M′ ) Ag) upon reaction
with suitable M′ salts. The crystal structures of the most significant compounds are reported herein.
Compound [Ag2{Ag(RSNS)}2(OTf)2] was also isolated and structurally characterized, representing a model
for the intermediate species of the aforementioned assembly.
chromatography, as drugs,8 and as NLO chromophores.9 As far
as zwitterionic coordination compounds are concerned, their
Introduction
Zwitterionic compounds are defined by the on-line IUPAC
Compendium of Chemical Terminology1 as “Neutral compounds
having formal unit electrical charges of opposite sign”. However,
zwitterionic metal complexes need a more detailed description,
which has been given by Remi Chauvin in his review concerning
zwitterionic organometalates.2 Indeed, couples of opposite
charges may be easily evidenced in the Lewis structures
although it is often possible to define resonance forms in which
all the atoms are neutral. In this case the molecule cannot be
called zwitterion. In addition, single positive and negative
charges can be delocalized over a group of atoms, as carboxylate
groups in amino acids and betaines.
Single, nonpolymeric, neutral molecules containing more than
one charge couple3 may be generally called “multizwitterions,”
different from polyzwitterions, which refers to polymers con-
taining zwitterionic chain substituents.4 If further positive or
negative charges are present, ionic molecules can be called
zwitterion-cations or zwitterion-anions in order to distinguish
them from ordinary ions.5
most important and outstanding application is in metallocene-
10
catalyzed Ziegler-Natta polymerization or even as carriers
for membranes.11
Zwitterionic metal complexes can be prepared following
different strategies, the most common being as follows: (a) by
reaction of zwitterionic ligands with metal species12 (this is also
the case of the compounds presented in this paper); (b) by
generating the charge separation upon coordination;13 and (c)
by association of a positive (or negative) metal center with an
oppositely charged ligand maintaining the charge separation.14
In addition, zwitterionic complexes can be divided in two main
categories; the most common one regroups complexes in which
the metal center bears the formal positive charge, while the
second comprises the still uncommon “zwitterionic metalates”
whose metal center is formally negative.
Recently, the reaction between Ph2PNHPPh2 (dppa) and
isothiocyanates was reported by our group.15 Reaction of dppa
with EtNCS afforded the new zwitterionic ligand EtNC(S)Ph2-
PNPPh2C(S)NHEt (HEtSNS). Depending on the reaction condi-
As a consequence of the charge separation, a very strong
molecular electric dipole moment is observed depending on the
distance between the charges barycenters. This strong dipole
and ambiphilicity allow these “neutral ions” to be applied in a
wide range of fields. Molecular zwitterions or zwitterionic
polymers are studied as stationary phases6 or eluents7 in liquid
(8) Pagliara, A.; Carrupt, P.-A.; Caron, G.; Gaillard, P.; Testa, B. Chem. ReV.
1997, 97, 3385-3400.
(9) (a) Geskin, V. M.; Lambert, C.; Bredas, J.-L. J. Am. Chem. Soc. 2003, 125
(50), 15651-15658. (b) Lambert , C.; Stadler, S.; Bourhill, G.; Bra¨uchle
C. Angew. Chem., Int. Ed. Engl. 1996, 35 (6), 644-646.
(10) (a) Piers, W. E. Chem.sEur. J. 1998, 4 (1), 13-18. (b) Gerhard., E. Chem.
Commun. 2003, 13, 1469-1476. Strauch, J. W.; Erker, G.; Kehr, G.;
Frohlich, R. Angew. Chem., Int. Ed. 2002, 41, 2543-2546.
(11) Lee, H.; Kim, D. B.; Kim, S.-H.; Kim, H. S.; Kim, S. J.; Choi, D. K.;
Kang, Y. S.; Won, J. Angew. Chem., Int. Ed. 2004, 43 (23), 3053-3056.
(12) Galindo, A.; Miguel, D.; Perez, J. Coord. Chem. ReV. 1999, 193, 643-
690.
(13) Schmidbaur H. Angew. Chem., Int. Ed. 1983, 22, 907-927.
(14) (a) Ronig, B.; Schulze, H.; Pantenburg, I.; Wesemann, L. Eur. J. Inorg.
Chem. 2005, (2), 314-320. (b) Thomas, J. C.; Peters, J. C. J. Am. Chem.
Soc. 2003, 125 (29), 8870-8888.
(15) Asti, M.; Cammi, R.; Cauzzi, D.; Graiff, C.; Pattacini, R.; Predieri, G.;
Stercoli, A.; Tiripicchio; A. Chem.sEur. J. 2005, 11, 3413-3419.
(1) www.iupac.org/publications/compendium/index.html.
(2) Chauvin, R. Eur. J. Inorg. Chem. 2000, 4, 577-591.
(3) (a) Finnen, D. C.; Pinkerton, A. A.; Acta Crystallogr. 1997, C53, 1455-
1457. (b) Karame, I.; Tommasino, M. L.; Faure, R.; Fenet, B.; Lemaire,
M. Chem. Lett. 2004, 33 (2), 178-179.
(4) Lowe, A. B.; McCormick, C. L. Chem. ReV. 2002, 102 (11), 4177-4189.
(5) Gudat, D. Top. Curr. Chem. 2004, 232, 175-212.
(6) Nesterenko, P. N.; Haddad, P. R. Anal. Sci. 2000, 16 (6), 565-574.
(7) Yan, Z.; Yanyan, L.; Fritz, J. S.; Haddad, P. R. J. Chromatogr., A 2003,
1020 (2), 259-264.
9
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J. AM. CHEM. SOC. 2006, 128, 866-876
10.1021/ja0554110 CCC: $33.50 © 2006 American Chemical Society

Zwitterionic Metalates of Group 11 Elements
A R T I C L E S
Scheme 1
tions, other products were also identified and structurally
characterized. HEtSNS contains the zwitterionic functional
group P+C(S)N- whose coordinating properties were never
studied before. Its first completely characterized complex
[(EtSNS)Rh(CO)] is a zwitterionic metalate in which the
zwitterion-anion EtSNS- acts as an S,N,S-κ3 ligand. This
complex bears a high dipole moment, calculated by DFT
methods up to 17 D. Indeed, the computation showed that
the positive charge is mainly delocalized over the two P
atoms, whereas the negative one is distributed on the Rh-N
system.
In this paper, the preparation of new zwitterionic metalates
of Cu, Ag, and Au is described. These complexes were also
used as bidentate metalloligand building blocks for the rational
assembly of multizwitterionic clusters, whose structures, deter-
mined by X-ray diffraction, are reported and show interesting
features.
Indeed, as evidenced by the bent geometry of the P-N-P group
of PPN+, the nitrogen may potentially coordinate a metal center
through the N atom lone pair, even though it has never been
found coordinating. In the case of the RSNS- complexes, the
[-Ph2PNPPh2-]+ coordination is forced by the S,S chelation
that brings N1 in the good geometry. The weak character of
the Cu-N bond can be deduced from the Cu-N [2.199(3) Å]
and Cu-S [2.158(2) Å] bond lengths, respectively, notably
longer and shorter than those typically observed for CuI species.
The aforementioned reaction has been extended to Ag(I) and
Au(I) (Scheme 2). Reaction of HRSNS with AgOTf and t-BuOK
(OTf- ) CF3SO3-) afforded complexes [Ag(RSNS)] (R ) Me,
2a; R ) Et, 2b) in quantitative yields. Compound 2a was
structurally characterized by X-ray diffraction methods and was
found to crystallize as a dimer. In the crystals two crystal-
lographic independent molecules (A and B) are found lying on
symmetry centers. A view of the crystal structure of one of the
two independent molecules (A) is given in Figure 2. A
comparison between the crystallographic geometric parameters
of the two independent molecules is reported in Table 1.
The ligand coordinates to the metal centers through the sulfur
atoms, found one in terminal and one in bridging modality, in
such a way that a four-membered planar Ag2S2 ring is formed.
The S1-Ag1-S2 angles [137.08(9)° for molecule A, 136.2-
(1)° for molecule B] are smaller than the analogue S-Cu-S
angle in 1b [167.88(5)°], as a result of the bridging coordination.
Results and Discussion
Reactions of RNHC(S)PPh2NPPh2C(S)NR (HRSNS; R )
Me, Et) with MI Group 11 Species. Reaction of [Cu(MeCN)4]-
[PF6] with HRSNS in a 1:1 molar ratio afforded [Cu(RSNS)]
(R ) Me, 1a; R ) Et, 1b) in quantitative yields (Scheme 1,
charge locations have formal character). A more convenient
synthetic route implies the use of CuCl, although a lower yield
is obtained. Deprotonation of HRSNS was achieved using
t-BuOK, forming in both cases insoluble potassium salts and
t-BuOH.
Complex 1b was structurally characterized by X-ray diffrac-
tion methods (Figure 1; for clarity, the atoms are depicted as
spheres. Ortep views of the crystal structures of all the
compounds with thermal ellipsoids are reported in the Support-
ing Information) and displayed a crystallographically imposed
C2 symmetry, the 2-fold axis passing through the Cu1 and N1
atoms.
The metal is coordinated in a distorted T-shaped geometry
[S1-Cu1-S1′ ) 167.88(5)°] through S1, S1′, and N1. The PNP
system maintains geometric parameters comparable to those
found for the free ligand [P1-N1 distance, 1.581(2) Å; P1-
N1-P1′ angle, 143.6(2)°]. N1 adopts a planar geometry, being
the sum of the bond angles 360°. The S1-C1 bond length is
typical for C-S single bonds, while the N2-C1 one suggests
a double bond character.
Complexes 1a and 1b can be well compared with [(EtSNS)-
Rh(CO)]15 and therefore considered as zwitterionic metalates.
The formal negative and positive charges are located over the
copper and the two phosphorus atoms, respectively. The two
fused penta-atomic Cu, S, C, P, N rings are formed by five
different atoms. The [-Ph2PNPPh2-]+ cationic group can be
associated with the classical [Ph3PNPPh3]+ cation (PPN+).
Figure 1. View of the crystal structure of complex 1b. Symmetry
transformations (′): -x, y, -z + 1/2. Selected bond distances (Å) and angles
(deg): Cu1-S1 2.158(2), Cu1-N1 2.199(3), P1-N1 1.581(2), P1-C1
1.838(3), S1-C1 1.745(4), N2-C1 1.265(4); S1-Cu1-S1′ 167.88(5), S1-
Cu1-N1 96.06(3), N1-P1-C1 108.83(2), C1-S1-Cu1 101.69(1), P1′-
N1-P1 143.6(2), P1-N1-Cu1, 108.2(1), S1-C1-P1 116.5(2).
9
J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006 867

A R T I C L E S
Scheme 2
Pattacini et al.
Table 1. Selected Bond Distances (Å) and Angles (deg) for
Complex 2a (Crystallographically Independent Molecules A and B)
that observed in compound 1b, indicating a less pronounced
sp2 character for the nitrogen atoms also due to the weaker
coordination interaction.
bond distances (Å)
molecule A
bond distances (Å)
molecule B
The NMR data suggest that the dimer dissociates in solution
at room temperature, as deduced by their 31P NMR spectra: 2a
and 2b display a narrow singlet in the typical range for
coordinated RSNS-, instead of two signals expected for the
dimer. In the 1H spectrum, the 2a methyl groups are equivalent
and resonate as doublets with the protons coupled with the closer
31P nucleus. The methylene groups of 2b are also equivalent
and resonate as a doublet of quartets, being coupled also with
Ag1-Ag1′ 3.125(2)
Ag1-N1 2.635(6)
Ag1-S1 2.576(3)
Ag1-S2 2.462(3)
Ag1-S1′ 2.678(3)
P1-N1 1.566(6)
P2-N1 1.607(6)
Ag1-Ag1′ 2.997(2)
Ag1-N1 2.721(6)
Ag1-S1 2.438(4)
Ag1-S2 2.566(3)
Ag1-S1′ 2.680(3)
P1-N1 1.562(6)
P2-N1 1.607(6)
bond angles (deg)
molecule A
bond angles (deg)
molecule B
1
the methyl protons. The H NMR spectra of complex 2b has
S1-Ag1-S2 137.08(9)
Ag1-S1-Ag1′ 72.98(8)
S2-Ag1-Ag1′ 167.39(8)
S2-Ag1-S1′ 115.8(1)
S1-Ag1-S1′ 107.02(8)
N1-Ag1-Ag1′ 106.4 (1)
P2-N1-P1 139.6(4)
S1-Ag1-S2 136.2(1)
Ag1-S1-Ag1′ 69.65(7)
S2-Ag1-Ag1′ 166.34(8)
S2-Ag1-S1′ 113.3 (1)
S1-Ag1-S1′ 110.35(7)
N1-Ag1-Ag1′ 107.7(1)
P2-N1-P1 138.5(4)
been recorded in CDCl3 in the temperature range 298-230 K.
The methylene and methyl group signals broadened at low
temperatures, but no further signals were observed down to 230
K (the methylene group signal at different temperatures has been
reported in the Supporting Information).
Reaction of [(tht)AuCl] (tht ) tetrahydrothiophene) with
HEtSNS and t-BuOK afforded compound [Au(EtSNS)] (3),
whose crystal structure is shown in Figure 3. In the crystal
structure of complex 3 the anion EtSNS- chelates the metal
center through the two sulfur atoms in an S,S-κ2 fashion. The
coordination is almost linear [S2-Au1-S1, 177.73(6)°; Au1-
S2, 2.280(2) Å; Au1-S1, 2.290(2) Å] and gives rise to an eight-
Figure 2. View of the crystal structure of complex 2a (molecule A).
Symmetry transformations (′): -x, -y, -z.
The two independent molecules show remarkable structural
differences. In fact, the Ag1A-Ag1A′ distance is longer than
the Ag1B-Ag1B′ one [3.125(2) and 2.997(2) Å, respectively],
while the Ag1A-N1A distance is shorter than the analogue
Ag1B-N1B one [2.635(6) Å and 2.721(6) Å, respectively].
Moreover, the distances between Ag1A and Ag1B from the
planes defined by P1A, N1A, P2A and P1B, N1B, P2B are
1.271(1) and 1.907(1) Å, respectively. These data indicate that
the shorter the Ag‚‚‚Ag separation, the longer the Ag‚‚‚N
separation (and vice versa); therefore, in complex 2a the Ag‚
‚‚N interactions may exist. The sum of the bond angles of N1A
and N1B (354.74(8)° and 347.49(8)°) differ significantly from
Figure 3. View of the crystal structure of complex 3. Selected distances
(Å) and angles (deg): Au1-S2 2.280(2), Au1-S1 2.290(2), S1-C1 1.759-
(6), S2-C4 1.764(6), P1-N1 1.584(4), P2-N1 1.582(4), P1-C1 1.848-
(5), P2-C4 1.858(5), N2-C1 1.265(6), N3-C4 1.255(6); S2-Au1-S1
177.73(6), C1-S1-Au1 102.9(2), C4-S2-Au1 105.8(2), N1-P1-C1
109.8(2), N1-P2-C4 114.3(2), P2-N1-P1 144.0(3), S1-C1-P1 118.9-
(3), S2-C4-P2 121.6(3).
9
868 J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006

Zwitterionic Metalates of Group 11 Elements
A R T I C L E S
Scheme 3
membered chelation ring. The Au1‚‚‚N1 distance is 2.693(4)
Å, indicating the absence of an interaction between the two
atoms, as confirmed by the distance of Au1 from the plane
defined by P1, N1, and P2 [2.023(1) Å]; the sum of the angles
[P1-N1-P2, Au1‚‚‚N1-P1, and Au1‚‚‚N1-P2] around N1 is
347.04(5)°, similar to that observed for N1B of compound 2.
Complex 3 can be considered a classical 14-electron linear AuL2
complex. On the other hand, linear AuI chelates displaying a
180° bite angle are rather rare, most involving diphosphine and
polysulfide ligands and being, to the best of our knowledge, all
ionic.16
In the crystal packing, probably due to the dipole moment,
complexes 1b and 3 adopt a head to tail disposition, as observed
for [(EtSNS)Rh(CO)].15 Molecules all oriented in the same
direction are disposed in layers. Adjacent layers contain
molecules with opposite orientations.
Complexes 1, 2, and 3 are soluble in most organic solvents,
from low polar toluene to methanol but not in water or
hydrocarbons.
Assembly of [Cu(RSNS)] and [Ag(RSNS)] in Multizwit-
terionic Clusters. The mononuclear complexes 1a, 1b and 2a,
2b behave as metalloligands. The negative charge density on
the S-M-S groups induces reactivity toward metal cations.
Indeed, addition of MI species (M ) Ag, Cu) resulted in the
assembly of multinuclear cationic clusters with formation of
sulfur bridges. The 3:2 reactions of complexes 1a and 1b with
suitable CuI or AgI salts afforded quantitatively [Cu2{Cu-
(RSNS)}3][PF6]2 (R ) Me, 4a; R ) Et, 4b) and [Ag2{Cu-
(RSNS)}3][A]2 (R ) Et, A ) OTf-, 5a; R ) Me, A ) OTf-,
5b; R ) Et, A ) BF4-, 5c), respectively, as shown in Scheme
3 (for clarity, only one of the three ligands is completely
depicted; for the other two, only the sulfur atoms are evidenced).
In the same way, complexes 2a and 2b reacted with suitable
(16) (a) Chan, W.-H.; Mak, T. C. W.; Che, C.-M. J. Chem. Soc., Dalton Trans.
1998, 2275-2276. (b) Heuer, B.; Pope, S. J. A.; Reid, G. Polyhedron 2000,
19, 743-749. (c) Gibson, A. M.; Reid G. J. Chem. Soc., Dalton Trans.
1996, 1267-1274.
AgI salts yielding [Ag2{Ag(RSNS)}3][A]2 ( R ) Me, A ) PF6
,
-
6a; R ) Et, A ) OTf-, 6b). Reaction of complexes 2a and 2b
9
J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006 869

A R T I C L E S
Pattacini et al.
Figure 4. Views of the crystal structure of the 4a cation. Phenyls omitted in structure I. View along the Cu4-Cu5 line in structure II. Selected bond lengths
[Å] and angles [deg]: Cu1-Cu5 2.893(1), Cu1-Cu4 2.904(1), Cu2-Cu5 2.846(1), Cu2-Cu4 2.887(1), Cu3-Cu5 2.841(1), Cu3-Cu4 2.891(1), Cu1-N1
2.163(5), Cu2-N4 2.178(5), Cu3-N7 2.185(5), Cu1-S1 2.195(2), Cu1-S2 2.195(2), Cu2-S3 2.189(2), Cu2-S4 2.190(2), Cu3-S6 2.181(2), Cu3-S5
2.194(2), Cu4-S2 2.273(2), Cu4-S4 2.301(2), Cu4-S6 2.237(2), Cu5-S3 2.258(2), Cu5-S1 2.276(2), Cu5-S5 2.298(2); Cu5-Cu1-Cu4 82.48(4), Cu5-
Cu2-Cu4 83.62(4), Cu5-Cu3-Cu4 83.64(4), Cu2-Cu4-Cu3 77.00(4), S2-Cu1-S1 165.58(8), S3-Cu2-S4 159.95(8), S6-Cu3-S5 162.14(8).
Figure 5. Views of the crystal structure of the 5c cation. Phenyls omitted in structure I. View along the Ag1-Ag2 line in structure II. Selected bond lengths
[Å] and angles [deg]: Ag1-S1 2.522(7), Ag1-Cu1 2.882(6), Ag1-Ag2 3.149(7), Ag2-S2 2.512(7), Ag2-Cu1 2.916(6), Cu1-N1 2.162(8), Cu1-S1
2.180(5), Cu1-S2 2.176(5); Ag2-Cu1-Ag1 65.78(19), S1-Cu1-S2 166.57(9). Symmetry transformations (′): -y, x - y, z; (′′) -x + y, -x, z.
with [Cu(MeCN)4]PF6 did not give the expected [Cu {Ag-
(RSNS)}3][PF6]2 clusters.
crystallographically imposed C3 symmetry, the axis passing
through Ag1 and Ag2.
2
Looking at the formal charge distribution, they can be
regarded as trizwitterionic, dicationic pentanuclear clusters.
Views of the crystal structures of clusters 4a, 5c, and 6a are
depicted in Figures 4, 5, and 6, respectively (anions omitted
for clarity).
For all the three structures, the ligand’s sulfur atoms bridge
the M′-M bonds. Each nitrogen of the P-N-P groups
coordinates to an M atom. All the [M(RSNS)] unities are tilted
in the same direction with respect to the relative M′, M, M′
Single crystals of compound 4a, 5c, 6a were obtained,
permitting their crystal structure determination. They are ionic
compounds; the cation is formed by three [M(RSNS)] units
joined together by two M′ atoms (M ) M′ ) Cu for 4a, M )
Cu, M′ ) Ag for 5c, M ) M′ ) Ag for 6a). The metal centers
define a trigonal bipyramidal M3M′2 core, with the M′ atoms
in the axial positions. In the crystals of cluster 6a, two
crystallographic independent molecules were present, displaying
analogous structures, while the cation of cluster 5c adopts a
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Zwitterionic Metalates of Group 11 Elements
A R T I C L E S
Figure 6. Views of the crystal structure of the 6a cation (crystallographically independent molecule A). Phenyls omitted in structure I. View along the
Ag4-Ag5 line in 6II. Selected bond lengths [Å] and angles [deg] (for molecule B are given in square brackets): Ag5-Ag1 3.0539(17) [3.149(2)], Ag5-
Ag2 3.1092(12) [3.0603(14)], Ag5-Ag3 3.2386(16) [3.1872(12)], Ag4-Ag3 3.0453(14) [3.0818(17)], Ag4-Ag1 3.1574(12) [3.1230(12)], Ag4-Ag2 3.220-
(2) [3.2282(14)], Ag5-S1 2.461(3) [2.464(3)], Ag5-S5 2.468(3) [2.468(3)], Ag5-S3 2.489(3) [2.484(3)], Ag4-S4 2.459(3) [2.500(3)], Ag4-S2 2.474(3)
[2.481(3)], Ag4-S6 2.486(3) [2.445(3)], Ag1-S1 2.410(3) [2.405(3)], Ag1-S2 2.412(3) [2.390(3)], Ag2-S3 2.402(3) [2.392(3)], Ag2-S4 2.415(3) [2.373-
(3)], Ag3-S5 2.387(3) [2.400(3)], Ag3-S6 2.408(3) [2.382(3)], Ag1-N1 2.523(6) [2.550(6)], Ag2-N4 2.524(6) [2.503(6)], Ag3-N7 2.484(6) [2.520(7)];
Ag5-Ag1-Ag4 88.59(3) [87.48(3)], Ag5-Ag2-Ag4 86.52(3) [87.14(4)], Ag4-Ag3-Ag5 87.27(4) [87.51(3)], S1-Ag1-S2 168.83(9) [170.42(9)], S3-
Ag2-S4 171.98(9) [170.14(9)], S5-Ag3-S6 170.90(9) [170.94(9)].
17
18
Although few examples of Cu5 and Ag5 clusters bearing
these types of metal cores have been already reported, these
are the first cases in which the cage supports positive charges.
Cluster 5c represents one of the rare examples of complexes
displaying an Ag-Cu bond [2.882(6) and 2.916(6) Å for Ag1-
Cu1 and Ag2-Cu1]. Surprisingly, molecules containing the
Cu-Ag interaction are very rare, whereas Cu-Au and Ag-
Au bonds are rather common. To the best of our knowledge,
only four structurally defined complexes bearing the aforemen-
tioned bond are reported in the literature.19 A theoretical study
is, in our opinion, needed to clarify this observation.
Figure 7. Comparison between the cores of the 4a, 5c, and 6a cations.
Clusters 4a, 5c, and 6a are stable when exposed to moderate
heat, to air, or to light. They can, nevertheless, be disassembled
if reacted with anions as CN- (fast) or Cl- (slower). The apical
MI ions are subtracted forming the respective salts, and the
parent [M(RSNS)] complexes are released.
The formation of 4a, 4b, 5a, 5b, 5c and 6a, 6b suggested
that any combination of M(RSNS) and MI (M ) Cu, Ag) could
lead to the assembly of clusters with desired compositions and
geometries. However, the 3:2 reaction of complex [Ag(EtSNS)]
(2b) with [Cu(MeCN)4]PF6 did not give rise to the expected
[Cu2{Ag(EtSNS)}3][PF6]2 cluster but to a mixture of species,
of which [Ag2{Cu(EtSNS)}3]2+ resulted as the major one, as
Table 2. Comparison between Selected Distances and Angles in
Clusters 4a, 5c, and 6a
4a
5c
6a
M′‚‚‚M′ (Å)
3.821(1)
2.877(1)
83.25(4)
80.65(4)
3.149(7)
2.899(6)
65.8(2)
94.8(1)
4.337(2)
3.138(1)
87.42(3)
77.51(3)
average M-M′ (Å)
average M′-M-M′ (deg)
average M-M′-M (deg)
plane (Figures 4II, 5II, 6II). The clusters’ core drawings are
reported and compared in Figure 7, and the most important
geometric parameters are given in Table 2.
It is noteworthy that the core geometry of cluster 5c differs
significantly from cluster 4a and 6a. A distortion of the
bipyramid is observed, being the two M′ axial atoms are much
closer. An interaction probably exists between the two Ag atoms,
being the Ag‚‚‚Ag distance is 3.149(7) Å. In consequence, the
average M′-M-M′ angles are smaller [65.8(2)° for cluster 5c,
83.25(4)° and 87.42(3)° for cluster 4a and 6a, respectively].
The apical metal centers are farther from the plane defined by
the three neighbor sulfur atoms [distances from the planes:
0.234(1) and 0.244(1) Å for Cu4 and Cu5, respectively, in 4a;
0.449(1) and 0.625(2) Å for Ag1 and Ag2 in 5c, respectively;
spanning from 0.198(1) and 0.231(1) Å for 6a].
(17) (a) Dance, I. G. Chem. Commun. 1976, 68-69. (b) Eichhofer, A.; Fenske,
D.; Holstein, W. Angew. Chem. 1993, 32, 242-245. (c) Hakansson, M.;
Eriksson, H.; Ahman, A. B.; Jagner, S. J. Organomet. Chem. 2000, 595,
102-108. (d) Edwards, P. G.; Gellert, R. W.; Marks, M. W.; Bau, R. J.
Am. Chem. Soc. 1982, 104, 2072-2073. (e) Heine, A.; Stalke, D. Angew.
Chem. 1993, 32, 121-122.
(18) (a) Abu-Salah, O. M.; Al-Ohaly, A. R. A.; Mutter, Z. F. J. Organomet.
Chem. 1990, 389 (3), 427-34. (b) Bowmaker, G. A.; Tan, L.-C. Aust. J.
Chem. 1979, 32 (7), 1443-52.
(19) (a) Freeman, M. J.; Green, M.; Orpen, A. G.; Salter, I. D.; Stone, F. G. A.
Chem. Commun 1983, 1332-1334. (b) Abu-Salah, O. M.; Hussain, M. S.;
Schlemper, E. O. Chem. Commun. 1988, 212-213. (c) Fackler, J. P., Jr.;
Lopez, C. A.; Staples, R. J.; Wang, Suning; Winpenny, R. E. P.; Lattimer,
R. P. Chem. Commun. 1992, 146-148. (d) Shorrock, C. J.; Xue, B.-Y.;
Kim, P. B.; Batchelor, R. J.; Patrick, B. O.; Leznoff, D. B. Inorg. Chem.
2002, 41, 6743-6753.
9
J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006 871

A R T I C L E S
Pattacini et al.
Figure 8. ESI-MS spectra of the crude product of the 3:2 reaction between
[Ag(EtSNS)] (compound 2a) and [Cu(MeCN)4][PF6] in CH2Cl2.
detected by ESI-MS analyses and confirmed by means of 31P
NMR spectroscopy. The formation of the cluster with inverted
metal ratio (Ag2Cu3 instead of Ag3Cu2) can be explained by
the RSNS- ligand exchange: [Ag(RSNS)] + Cu+ ) [Cu-
(RSNS)] + Ag+. Several [M2{M′(RSNS)}3]2+ cations (M )
Ag, Cu; M′ ) Ag, Cu) were detected in the ESI-MS spectrum
of the crude product (Figure 8), [Ag2{Cu(EtSNS)}3]2+ (cluster
5b) being the prevalent one. Together with the [Ag2{Cu-
(EtSNS)}3]2+ 1041 m/z peak (intensity 100), other signals with
m/z 1019 and 1063 were observed, respectively correspondent
to the [Cu4Ag(EtSNS)3] 2+ and [Cu2Ag3(EtSNS)3]2+ ions (rela-
tive intensities 6%). Moreover, low intensity peaks 996, 1085,
and 1107 m/z were respectively associated with [Cu5(EtSNS)3]2+,
[Ag4Cu(EtSNS)3]2+, and [Ag5(EtSNS)3]2+. The 31P NMR
spectrum showed several singlets, in the range of coordinating
EtSNS- [δ 13.91 ppm (relative intensity 0.15); 13.79 (0.16);
13.47 (0.28); 13.12 ([Ag2{Cu(EtSNS)}3]2+, 1); 12.83 (0.14);
12.72 (0.16)]. The most intense signal belonged to [Ag2{Cu-
(EtSNS)}3]2+ (5b), as in the case of the ESI-MS spectrum. The
NMR data suggest that the metal scrambling process occurs in
solution and seems not induced by the ESI-MS experimental
conditions. In addition, cluster 5b can be isolated in high yields
by crystallization. Similar ESI-MS and 31P NMR spectra were
observed in the case of the reaction between complex 1b and
AgOTf. In this case, however, the relative intensities of the [Ag2-
{Cu(EtSNS)}3]2+ signals are much more intense, and the other
clusters can be considered as impurities.
Figure 9. View of the crystal structure of compound 7. Selected bond
lengths [Å] and angles [deg]: Ag1‚‚‚Ag2′ 3.174(2), Ag1‚‚‚Ag2 3.259(2),
Ag1-S2 2.405(2), S2-Ag2′ 2.399(2), Ag1-S1 2.416(2), Ag2-S1 2.414-
(2), Ag1-N1 2.572(4), Ag2-O1 2.465(4); Ag1-Ag2-Ag1′ 79.31(3),
Ag2-Ag1-Ag2′ 100.69(3), Ag2-S1-Ag1 84.87(8), Ag2′-S2-Ag1 82.73-
(7), S2-Ag1-S1 164.70(7), S2′-Ag2-S1 154.23(6), S2-Ag1-N1 85.89-
(12), S1-Ag1-N1 86.57(11).
geometrical parameters comparable with those found for the
RSNS- species described above. Examples of quasi-planar
Ag4S4 core complexes were already reported in the literature.20
When complex 7 is reacted, in a 1 to 1 ratio, with complex
2b, cluster [Ag2{Ag(EtSNS)}3][OTf]2 (6b) is quantitatively
formed, as depicted in Scheme 4 (for clarity, only one of the
three ligand molecules is completely shown for cluster 6; for
the other two, only the S bridging atoms have been evidenced).
Since complex 7 is an intermediate species in the assembly
of cluster 6b, it is possible to hypothesize an analogous planar
Cu4 intermediate in the formation of 4a and 4b and Cu2Ag2
ones for 5a, 5b, 5c. In the case of silver, the coordinating triflate
anion may stabilize the tetranuclear species, allowing its
isolation. Cluster 6b can be thus assembled following three
different strategies: (a) 5:3 reaction of AgOTf with HEtSNS
in the presence of a base such as t-BuOK, (b) 3:2 reaction of
complex 2b with AgOTf, and (c) 1:1 reaction of complex 6b
with complex 2b.
The reaction ratio between the complex M(RSNS) and the
MI ion can be different from 3:2. In fact, reaction of [Ag-
(EtSNS)] (2b) with AgOTf in a 1:1 molar ratio led quantitatively
to the formation of [Ag2{Ag(EtSNS)}2(OTf)2] (7), a bis-
zwitterion. A view of its crystal structure is shown in Figure 9.
In the centrosymmetric crystal structure of complex 7, the
Ag(EtSNS) groups are bound to two AgOTf groups, the four
metal centers forming a planar Ag4 ring. The Ag‚‚‚Ag separa-
tions [Ag1‚‚‚Ag2′ 3.174(2), Ag1‚‚‚Ag2 3.259(2) Å] suggest
metal-metal interactions and are longer than those found in
the dimeric crystal structure of complexes 2a [Ag1-Ag1′ 3.125-
(2) and Ag1-Ag1′ 2.997(2)Å for 2aA and 2aB, respectively]
and slightly longer than those found for cluster 6 [average Ag-
Ag bond length: 3.138(1)Å]. The N1-Ag1 distance [2.572(4)
Å] is shorter than those found for complex 2b, while the sulfur
atoms bridge two metals almost symmetrically. Ag2 is finally
bound to an oxygen of a triflate ion. The N1-Ag1 line form
an angle of 111.86(6) with the Ag4 plane. The ligand maintains
Preliminary results indicate high Stoke’s shift luminescence
properties for clusters 4(a, b) and 5(a, b, c). The emission
spectrum of a crystalline powder sample of cluster 4b was
recorded under a 380 nm continuous excitation radiation at room
temperature and at 10 K. They show rather wide bands (Figure
8 in the Supporting Information) ranging from 550 to 760 nm
with a maximum at 653 nm at 10 K and ranging from 550 to
737 nm with a maximum at 637 nm at 298 K.
Conclusions
Zwitterionic metalates are still uncommon in the literature,
and their potential applications in catalysis and material science
(20) (a) Wojnowski, W.; Wojnowski, M.; Peters, K.; Peters, E.-M.; von
Schnering, H. G. Z. Anorg. Allg. Chem. 1985, 530, 79-88. (b) Tang, K.;
Aslam, M.; Block, E.; Nicholson, T.; Zubieta J. Inorg. Chem. 1987, 26,
1488-1497. (c) Fackler J. P. J.; Lopez, C. A.; Staples, R. J.; Wang, S.;
Winpenny, R. E. P.; Lattimer, R. P. Chem. Commun. 1992, 146-148. (d)
Richter, R.; Dietze, F.; Schmidt, S.; Hoyer, E.; Poll, W.; Mootz, D. Z.
Anorg. Allg. Chem. 1997, 623, 135-140.
9
872 J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006

Zwitterionic Metalates of Group 11 Elements
A R T I C L E S
Scheme 4
free reaction between EtNCS and dppa increased the yield to almost
quantitative. Moreover, protonation of the ligand with aqueous HCl
permitted us to avoid spontaneous solid-state decomposition in EtNC
and EtNHC(S)PPh2NP(S)Ph2, the chlorhydrate HEtSNS‚HCl being
more stable than the neutral product.
are all to be explored. The presence of an electron-rich metal
center can be exploited for instance in catalytic reactions and
the very strong molecular electrical dipole in NLO applications.
The Cu, Ag, and Au complexes reported in this paper continue
the series of HRSNS complexes and show that their properties
as metalloligands can be extended to other metals in order to
produce a series of rationally assembled multizwitterions.
Multizwitterionic molecules such as those reported in this paper
can show useful properties due to the presence of strong ordered
dipoles and are under study. As an example, complexes 4(a,b),
5(a,b,c), and 6(a,b) can be considered a new kind of octupolar
molecule21 where three dipoles are disposed with C3 symmetry
in a tangential, rather than radial, way. The assembly of mono-
and bimetallic clusters using complex [Au(EtSNS)] (compound
3) is under study as the coordination chemistry of HRSNS
toward other metals of the transition series.
2 g of dppa (3.9 mmol) were dissolved in 3 mL of RNCS (R ) Me,
41.1; R ) Et, 34.5 mmol), and the mixture was stirred at 32 °C for 20
min (R ) Me) or at 25 °C for 20 min (R ) Et). After this time, hexane
(30 mL) was added, and a yellow solid formed. This precipitate was
in turn filtered and washed with hexane (4 × 20 mL) in order to obtain
HRSNS (R ) Me, Et) as yellow crystalline powders. HEtSNS was
identified by comparison of its spectroscopic data with that reported
previously.15 Yield: HEtSNS 92%, HMeSNS 49%.
HMeSNS E.A. (%) calcd for C28H27N3P2S2: N, 7.90; C, 63.26; H,
5.12; S, 12.06. Found: N, 7.88; C, 63.82; H, 5.19; S, 11.95. 1H NMR
(300 MHz, CDCl3, 25 °C, δ ppm): 7.7-7.3 (m, 20H; Ph), 3.45 (d,
3
6H, -CH3, J(H-H) ) 2.7 Hz), 3.44 (s, 1H; S-H). 31P{1H} NMR
(161.98 MHz, CDCl3, 25 °C): δ ) 7.6 (s).
Experimental Section
Preparation of H2EtSNSCl. HCl (2 mL, 12 M) was added to a
solution of HEtSNS (500 mg, 0.90 mmol) in CH2Cl2 (30 mL), and the
reaction stirred for 15 min at 25 °C. To the suspension, anhydrous
Na2SO4 was added, and the solution was filtered. Evaporation of the
solvent gave a pale green-yellow solid. The solid was treated by addition
of amounts of MeOH (3 × 5 mL) followed by evaporation. The solid
obtained was then washed with toluene (4 × 10 mL), yielding H2-
EtSNSCl as a yellow-green microcrystalline powder. Yield: 91%.
The same procedure yielded H2MeSNSCl when HMeSNS was used
instead of HEtSNS (500 mg, 0.94 mmol). Yield: 69%. The HMeSNS
and H2MeSNSCl 1H NMR spectra are discussed in the Supporting
Information.
General Remarks. t-BuOK, EtNCS, MeNCS, AgPF6, AgBF4, and
AgOTf were purchased pure (Aldrich and Fluka) and used as received.
[Cu(MeCN)4][BF4], [Cu(MeCN)4][PF6],22 [(tht)AuCl],23 and dppa (Ph2-
PNHPPh2)24 were prepared following the procedures reported in the
literature. The solvents (Fluka) were dried and distilled by standard
techniques. Elemental (C, H, N, S) analyses were performed on a Carlo
1
Erba EA 1108 instrument. H (300 MHz, CDCl3, TMS) and 31P{1H}
(161.98 MHz, CDCl3, 85%-H3PO4) NMR spectra were recorded on
Bruker spectrometers (Avance 300 and AMX-400, respectively). FTIR
spectra were recorded on a Nicolet NEXUS spectrometer. A Quattro
LC triple quadrupole instrument (Micromass, Manchester, UK) equipped
with an electrospray (ESI) interface and a Masslynx v. 3.4 software
(Micromass) was used for ESI-MS data acquisition and processing.
The nebulizing gas (nitrogen, 99.999% purity) and the desolvation gas
(nitrogen, 99.998% purity) were delivered at a flow rate of 80 and 500
L/h, respectively. ESI-MS analyses were performed by operating the
mass spectrometer in positive ion (PI) mode, acquiring mass spectra
over the scan range m/z 100-2800, using a step size of 0.1 Da and a
scan time of 2.7 s. The operating parameters of interface were as
follows: source temperature 70 °C, desolvation temperature 70 °C,
ESI(+) capillary voltage 3.0 kV, cone voltage 15 V, rf lens 0.3 V. The
emission spectra were recorded under 380 nm continuous excitation
light using a Spex Fluorolog System. A xenon lamp was used as the
source, and the detector was an RCA C31034 photomultiplier. The
samples were mounted onto an Air Products closed-cycle helium
cryostat. The spectra were measured at room temperature and 10 K.
Preparation of HRSNS (R ) Me, Et). The synthesis of HEtSNS
has been improved with respect to that reported previously.15 A solvent-
H2EtSNSCl E.A. (%) calcd for C30H32N3ClP2S2: N, 7.05; C, 60.44;
1
H, 5.41; S, 10.76. Found: N, 6.89; C, 60.53; H, 5.19; S, 10.95. H
NMR (300 MHz, CDCl3, 25 °C, δ ppm): 12.35 (s, 2H; N-H), 7.54-
7.26 (m, 20H; Ph), 4.06 (observed multiplicity: quintet, 4H; -CH2-,
3
1
3
4J(H-P) ) J(1H, H) ) 6.7 Hz), 1.44 (t, 6H, -CH3, J(H-H) ) 6.7
Hz). 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C): δ ) 14.2 (s).
H2MeSNSCl E.A. (%) calcd for C28H28N3ClP2S2: N, 7.40; C, 59.20;
1
H, 4.97; S, 11.29. Found: N, 7.33; C, 59.25; H, 4.96; S, 11.37. H
NMR (300 MHz, CDCl3, 25 °C, δ ppm): 12.67 (s, 1H; N-H), 7.2-
7.7 (m, 20H; Ph), 3.44 (d, 6H; -CH3, 3J(H-H) ) 3.3 Hz), 2.03 (s, br,
1H, S-H). 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C): δ ) 14.9 (s).
Preparation of [Cu(RSNS)] (R ) Me, 1a; R ) Et, 1b). (a) A
solution of HRSNS (112 mg R ) Et, 106 mg R ) Me; 0.2 mmol) in
CH2Cl2 (20 mL) was added to a solution of [Cu(MeCN)4]PF6 (74 mg,
0.2 mmol) in CH2Cl2 (20 mL), resulting in an orange reaction mixture.
t-BuOK (22 mg, 0.2 mmol in 5 mL of MeOH) was then added, and
the color of the solution changed to pale yellow. Stirring was continued
for 30 min. The solvent was evaporated, and the pale yellow powder
obtained redissolved in CH2Cl2 (20 mL). KPF6 was removed via
filtration. 10 mL of hexane were added in order to separate a yellow
oil, removed by centrifugation. Evaporation of the solvent afforded
complexes [Cu(RSNS)] (R ) Me, Et; 1a and 1b, respectively) as white
powders. Yields: 1a 81%, 1b 84%.
(21) Viau, L.; Bidault, S.; Maury, O.; Brasselet, S.; Ledoux, I.; Zyss, J.; Ishow,
E.; Nakatani, K.; Le Bozec, H. J. Am. Chem. Soc. 2004, 126 (27), 8386-
8387.
(22) Kubas, G. J. Inorg. Synth. 1979, 19, 90-92.
(23) Uso’n, R.; Laguna, A.; Laguna, M. Inorg. Synth. 1989, 26, 85.
(24) Bhattacharyya, P.; Woollins, J. D. Polyhedron 1995, 14 (23/24), 3367-
88.
9
J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006 873

A R T I C L E S
Pattacini et al.
Table 3. Crystal Data and Structure Refinement for Complexes
1b, 2a, and 3
(b) A solution of HRSNS (112 mg R ) Et, 106 mg R ) Me; 0.2
mmol) in CH2Cl2 (20 mL) was added to a suspension of CuCl (20 mg,
0.2 mmol) in CH2Cl2 (20 mL), resulting in an orange reaction mixture.
t-BuOK (22 mg, 0.2 mmol in 5 mL of MeOH) was in turn added, and
the color of the solution changed to pale yellow. After stirring for 2 h,
the solvent was removed, and the yellow powder redissolved in CH2-
Cl2 (20 mL). KCl was removed by filtration. Addition of hexane (10
mL) gave an oil which was removed by centrifugation. Evaporation of
the solvent afforded complexes [Cu(RSNS)] (R ) Me, Et; 1a and 1b,
respectively) as white powders. 1a 73%, 1b 69%.
complexes
1b
2a
3
formula
FW
crystal system monoclinic
space group
a, Å
b, Å
CuS2P2N3C30H30
622.17
Ag2S4P4N6C56H52
1276.9
monoclinic
P21/n
20.776(6)
14.173(4)
21.317(6)
90
117.89(5)
90
5548(5)
4
AuS2P2N3C30H30
755.60
monoclinic
P21/c
15.810(5)
10.699(4)
19.258(7)
90
113.459(8)
90
2988(7)
4
C2/c
15.752(4)
10.650(3)
19.510(5)
90
113.16(5)
90
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
1a: E.A. (%) calcd for C28H26N3P2CuS2: N, 7.07; C, 56.60; H, 4.41;
1
S, 10.79. Found: N, 7.15; C, 56.35; H, 4.67; S, 10.47. H NMR (300
3009 (1)
4
MHz, CDCl3, 25 °C, TMS): δ ) 7.2-7.5 (m, 20H; Ph), 3.66 (s, br,
6H; -CH3). 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C): δ 9.2 (s).
1b: E.A. (%) calcd for C30H30N3CuP2S2: N, 6.75; C, 57.91; H, 4.86;
D
calcd, g cm-3 1.373
1.529
1.680
F(000)
crystal size
(mm3)
µ, cm-1
rflns collected 15 546
rflns unique 2661
rflns observed 1744
[I > 2σ(I)]
parameters
R indices
[I > 2σ(I)]
R indices
(all data)
1288
2592
1488
1
0.23 × 0.17 × 0.12 0.20 × 0.09 × 0.15 0.54 × 0.45 × 0.20
S, 10.31. Found: N, 6.65; C, 58.08; H, 4.90; S, 10.22. H NMR (300
MHz, CDCl3, 25 °C, TMS): δ ) 7.2-7.5 (m, 20H; Ph), 3.8 (q, br,
3J(H,H) ) 6.5 Hz, 4J(H,P) ) 2.8 Hz, 4H; -CH2-), 1.22 (t, br, 3J(H,H)
) 6.5 Hz, 6H; -CH3); 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C,
H3PO4): δ ) 7.9 (s).
9.95
10.15
43 169
7745
51.95
6350
6173
3198
3726
Preparation of [Ag(RSNS)] (R ) Me, 2a; R ) Et, 2b). A solution
of HRSNS (112 mg R ) Et, 106 mg R ) Me; 0.2 mmol) in CH2Cl2
(20 mL) was added to a solution of AgOTf (51 mg, 0.2 mmol) in THF
(20 mL), and the color of the reaction mixture changed to pale brown.
t-BuOK (22 mg, 0.2 mmol in 5 mL of MeOH) was in turn added, and
stirring continued for 2 h. Evaporation of the solvent afforded a pale
yellow solid which was redissolved in CH2Cl2 (20 mL). KOTf was
removed by filtration. Addition of hexane (10 mL) gave a brown oil
which was removed by centrifugation. Evaporation of the solvent
yielded complexes [Ag(RSNS)]2 (R ) Me, Et; 2a and 2b, respectively)
as white powders. Yield: 2a 74%, 2b 83%.
186
505
343
R1 ) 0.0395
wR2 ) 0.0965
R2 ) 0.0715
wR2 ) 0.1059
R1 ) 0.0669
wR2 ) 0.1222
R2 ) 0.1421
wR2 ) 0.1368
R1 ) 0.0418
wR2 ) 0.482
R2 ) 0.1195
wR2 ) 0.0551
[PF6]2 (R ) Me, Et; 4a and 4b respectively) as yellow crystalline solids.
Yields: 4a 81%, 4b 83%.
(b) A solution of [Cu(MeCN)4]PF6 (74.5 mg, 0.2 mmol) in CH2Cl2
(15 mL) was added to a solution of 1a or 1b (178 mg or 186 mg,
respectively; 0.3 mmol) in CH2Cl2 (15 mL), resulting in a yellow
reaction mixture. Stirring was continued for 20 min. Evaporation of
the solvent afforded clusters 4a (from 1a) and 4b (from 1b) as yellow
crystalline powders. Yield: 4a 92%, 4b 96%.
2a: E.A. (%) calcd for C56H52N6Ag2P4S4: N, 6.58; C, 52.67; H, 4.10;
1
S, 10.04. Found: N, 6.37; C, 52.86; H, 4.36; S, 9.87. H NMR (300
MHz, CDCl3, 25 °C, TMS): δ ) 7.0-7.4 (m, 20H; Ph), 3.47 (d, 6H,
4J(H,P) ) 3.6 Hz, 4H; -CH3); 31P{1H} NMR (161.98 MHz, CDCl3,
25 °C, H3PO4): δ 10.3 (s).
4a: E.A. (%) calcd for C84H78N9Cu5F12P8S6: N, 5.73; C, 45.87; H,
1
3.57; S, 8.75. Found: N, 5.46; C, 44.65; H, 3.42; S, 8.24. H NMR
2b: E.A. (%) calcd for C60H60N6Ag2P4S4: N, 6.30; C, 54.06; H,
(300 MHz, CD2Cl2, 25 °C, TMS) δ ) 7.7-7.1 (m, 60H; Ph), 3.72 (d,
1
18H, 4J(H,P) ) 3.6 Hz; -CH3). 31P{1H} NMR (161.98 MHz, CDCl3,
4.54; S, 9.62. Found: N, 6.24; C, 54.41; H, 4.29; S, 9.55. H NMR
1
(300 MHz, CDCl3, 25 °C, TMS): δ ) 7.0-7.5 (m, 20H; Ph), 3.78
25 °C, H3PO4): δ ) 14.4 (s), -143.3 (sept, J(P,F) ) 711 Hz; PF6).
3
4
(dq, J(H,H) ) 7.2 Hz, J(H,P) ) 4.2 Hz, 4H; -CH2-), 1.93 (t, 6H,
3J(H,H) ) 7.2 Hz; -CH3); 31P{1H} NMR (161.98 MHz, CDCl3, 25
°C, H3PO4): δ 9.0 (s).
4b: E.A. (%) calcd for C90H90N9Cu5F12P8S6: N, 5.52; C, 47.34; H,
1
3.97; S, 8.42. Found: N, 5.36; C, 47.81; H, 4.09; S, 8.31. H NMR
(300 MHz, CD2Cl2, 25 °C, TMS): δ ) 7.75-7.15 (m, 60H; Ph), 4.04
(m, br, 6H; -CHH-), 3.87 (m, br, 6H; -CHH-), 1.34 (t, 18H, 3J(H,H)
) 7.2 Hz; -CH3). 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C, H3-
Preparation of [Au(EtSNS)] (3). A solution of HEtSNS (112 mg,
0.2 mmol) in CH2Cl2 (20 mL) was added to a solution of [(tht)AuCl]
(64 mg, 0.2 mmol) in CH2Cl2 (20 mL), resulting in a yellow reaction
mixture. t-BuOK (22 mg, 0.2 mmol in 5 mL of MeOH) was in turn
added, and stirring continued for 2 h. Evaporation of the solvent gave
a pale yellow solid which was redissolved in CH2Cl2 (20 mL). KCl
was removed by filtration. Addition of hexane (10 mL) afforded a
brown oil which was removed by centrifugation. Evaporation of the
solvent yielded complex [Au(EtSNS)] (3) as a white powder. Yield:
83%.
E.A. (%) calcd for C30H30N3AuP2S2: N, 5.56; C, 47.69; H, 4.00; S,
8.49. Found: N, 5.34; C, 47.41; H, 4.19; S, 8.55. 1H NMR (300 MHz,
CDCl3, 25 °C, TMS): δ ) 7.63-7.25 (m, 20H; Ph), 3.71 (dq, 3J(H,H)
) 7.2 Hz, 4J(H,P) ) 3.6 Hz, 4H; -CH2-), 1.21 (t, 6H, 3J(H,H) ) 7.2
Hz; -CH3). 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C, H3PO4): δ
10.9 (s).
Preparation of [Cu2{Cu(RSNS)}3][PF6]2 (R ) Me, 4a; R ) Et,
4b). (a) A solution of HRSNS (168 mg R ) Et, 159 mg R ) Me; 0.3
mmol) in CH2Cl2 (15 mL) was added to a solution of [Cu(MeCN)4]-
PF6 (186 mg, 0.5 mmol) in CH2Cl2 (15 mL), resulting in an orange
reaction mixture. t-BuOK (34 mg, 0.3 mmol in 5 mL of MeOH) was
in turn added, and stirring continued for 2 h. Evaporation of the solvent
gave the crude product which was in turn recrystallized by evaporation
from a CH2Cl2/hexane mixture, yielding complexes [Cu2{Cu(RSNS)}3]-
1
PO4): δ ) 12.2 (s), -144.4 (sept, J(P,F) ) 712 Hz; PF6). ESI-MS
[CH2Cl2 solution; m/z (rel int., formula)]: 503.2 (5%, Ph2(S)PNPPh2-
EtNCS+), 560.6 (5%, H2EtSNS+), 996.8 (100%, [Cu2{Cu(EtSNS)}3]2+
1307.5 (2%, [Cu2{Cu(EtSNS)}4]2+).
,
Preparation of [Ag2{Cu(RSNS)}3][A]2 (R ) Et, A ) OTf- 5a;
R ) Me, A ) OTf- 5b; R ) Et, A ) BF4-, 5c). A solution of AgOTf
(51 mg, 0.2 mmol) in THF (15 mL) was added to a solution of 1a or
1b (178 mg or 186 mg, respectively; 0.3 mmol) in CH2Cl2 (15 mL),
resulting in a yellow reaction mixture. Addition of hexane (30 mL)
afforded clusters 5a (from 1a) and 5b (from 1b) as microcrystalline
yellow powders. Yields: 5a 87%, 5b 93%. Cluster 5c was prepared
following the same procedure, using AgBF4 (39 mg) instead of AgOTf
and complex 1b (178 mg). Yield: 90%.
5a: E.A. (%) calcd for C86H78N9Ag2Cu3F6O6P6S8: N, 5.49; C, 44.98;
H, 3.42; S, 11.17. Found: N, 5.35; C, 45.44; H, 3.40; S 10.96. H
NMR (300 MHz, CDCl3, 25 °C, TMS): δ ) 7.6-7.3 (m, 60H; Ph),
3.72 (s, br, 18H; -CH3); 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C,
H3PO4): δ ) 16.3 (s).
1
5b: E.A. (%) calcd for C92H90N9Ag2Cu3F6O6P6S8: N, 5.30; C, 46.42;
H, 3.81; S, 10.78. Found: N, 5.35; C, 46.34; H, 3.73; S, 10.64. H
1
NMR (300 MHz, CDCl3, 25 °C, TMS): δ ) 7.60-7.26 (m, 60H; Ph),
3
3.85 (m, br, 12H; -CH2-), 1.31 (t, 18H; J(H,H) ) 7.2 Hz, -CH3).
9
874 J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006

Zwitterionic Metalates of Group 11 Elements
A R T I C L E S
Table 4. Crystal Data and Structure Refinement for Clusters 4a, 5c, 6a, and 7a
complexes
4a
5c
6a
7
formula
Cu5S6P6N9C84H78‚[PF6]‚
Cu3Ag2S6P6N9C90H90
‚2BF4
Ag5S6P6N9C84H78‚
2PF6‚4 toluene
2605.26
monoclinic
P21/c
16.478(7)
26.693(6)
52.329(8)
90
94.046(6)
90
22959(11)
8
Ag4S6P4O6C62F6H60‚
2CH2Cl2‚1/2MeOH
2385.23
monoclinic
P21/c
25.679(5)
14.502(5)
30.087(5)
90
109.262(5)
90
10577(5)
4
THF
FW
2255.87
hexagonal
P-3
17.955(5)
17.955(5)
17.601(4)
90
90
120
4914(2)
2
1.525
1918.98
monoclinic
P21/c
15.701(7)
13.750(5)
17.964(6)
90
98.935(9)
90
3831(7)
2
crystal system
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
D
calcd, g cm-3
1.497
1.507
1.663
F(000)
4820
2284
10 400
1904
crystal size (mm3)
0.34 × 0.21 × 0.19
0.23 × 0.32 × 0.24
0.52 × 0.34 × 0.33
0.18 × 0.51 × 0.39
µ, cm-1
13.97
13.19
11.24
13.22
rflns collect
rflns unique
rflns observed
[I > 2σ(I)]
parameters
R indices
45154
14 699
7712
23970
5710
2647
95683
39 980
11904
7302
7079
2639
1228
319
1881
379
R2 ) 0.0567
wR2 ) 0.1185
R2 ) 0.1331
wR2 ) 0.1389
R2 ) 0.0588
wR2 ) 0.1320
R2 ) 0.1376
wR2 ) 0.1433
R2 ) 0.0566
wR2 ) 0.1066
R2 ) 0.2004
wR2 ) 0.1203
R2 ) 0.0571
wR2 ) 0.0663
R2 ) 0.1890
wR2 ) 0.0809
[I > 2σ(I)]
R indices
(all data)
2
2
2
a R1 ) Σ||Fo| - |Fc||/Σ |Fo|. wR2 ) [Σ[w(Fo - Fc )2]/Σ [w(Fo )2]]1/2
.
31P{1H} NMR (161.98 MHz, CDCl3, 25 °C, H3PO4): δ ) 13.2 (s).
ESI-MS [CH2Cl2 solution; m/z (rel int., formula)]: 996.8 (<1%, [Cu2-
{Cu(EtSNS)}3]2+), 1019.0 (3%, [Cu4Ag(EtSNS)3]2+), 1041.2 (100%,
[Ag2{Cu(RSNS)}3]2+), 1063.3 (4%, [Cu2Ag3(EtSNS)3]2+), 1085.5
(<1%, [CuAg4(EtSNS)3]2+).
6b: E.A. (%) calcd for C92H90N9Ag5F6O6P6S8: N, 5.01; C, 43.96;
H, 3.61; S, 10.21. Found: N, 5.32; C, 43.74; H, 3.84; S, 10.37. H
1
NMR (300 MHz, CDCl3, 25 °C, TMS): δ ) 7.7-7.5 (m, 60H; Ph),
3.97 (m, br, 12H; -CH2-), 1.43 (t, br, 18H; -CH3). 31P{1H} NMR
(161.98 MHz, CDCl3, 25 °C, H3PO4): δ ) 12.2 (s). ESI-MS [CH2Cl2
solution; m/z (rel int., formula)]: 1066.1 (5%, [Ag2{Ag(EtSNS)}3]2+
- EtNC), 1107.7 (100%, [Ag2{Ag(EtSNS)}3]2+).
Preparation of Complex [{Ag(EtSNS)}2 {AgOTf}2 ] (7). (a) A
solution of AgOTf (51 mg, 0.2 mmol in 15 mL of THF) was added to
a solution of complex 2b (133 mg, 0.2 mmol, in 15 mL of THF).
Stirring was continued for 10 min. Addition of hexane resulted in the
precipitation of complex 7 as a white powder, purified by crystallization
from a THF solution.
5c: E.A. (%) calcd for C90H90N9Ag2B2Cu3F8P6S6: N, 5.59; C, 47.92;
H, 4.02; S, 8.52. Found: N, 5.73; C, 48.31; H, 3.99; S, 8.29. 1H NMR
(300 MHz, CDCl3, 25 °C, TMS): δ ) 7.8-7.3 (m, 60H; Ph), 3.86
(m, br, 12H; -CH2), 1.31 (t, 18H; 3J(H,H) ) 7.2 Hz, -CH3). 31P{1H}
NMR (161.98 MHz, CDCl3, 25 °C, H3PO4): δ ) 13.2 (s)
Preparation of Clusters [Ag2{Ag(RSNS)}3][A]2 (6a, R ) Me, A
) PF6-; 6b, R ) Et, A ) OTf-). (a) A solution of AgOTf (51 mg,
0.2 mmol in 15 mL of THF) was added to a solution of complex 2b
(200 mg, 0.3 mmol, in 15 mL of THF). Stirring was continued for 10
min. Addition of hexane afforded cluster 6b as a white powder, purified
by crystallization from a CHCl3/hexane solution. Yield: 91%. Cluster
6a was obtained following the same procedure, using AgPF6 (51 mg)
and complex 2a (192 mg) instead of AgOTf and complex 2b,
respectively. Yield: 85%.
(b) A solution of AgOTf (102 mg, 0.4 mmol in 15 mL of THF) was
added to a solution of HEtSNS (104 mg, 0.2 mmol, in 15 mL of THF).
t-BuOK was in turn added (22 mg, 0.2 mmol, in 5 of MeOH), and
stirring continued for 20 min. Evaporation of the solvent afforded a
white powder which was in turn redissolved in CH2Cl2. KCl was
filtered. Evaporation of the solvent yielded complex 7 as a white
powder.
(b) A solution of AgOTf (128 mg, 0.5 mmol in 15 mL of THF) was
added to a solution of HEtSNS (168 mg, 0.3 mmol, in 15 mL of THF).
t-BuOK (34 mg, 0.3 mmol, in tot of MeOH) was in turn added, and
stirring continued for 20 min. Evaporation of the solvent afforded a
white solid which was redissolved in CH2Cl2 (40 mL). KCl was
removed by filtration. Evaporation of the solvent yielded cluster 6b as
a white powder. Yield: 73%. Cluster 6a was obtained following the
same procedure, using AgPF6 (127 mg) and HMeSNS (159 mg) instead
of AgOTf and HEtSNS, respectively. Yield: 69%.
E.A. (%) calcd forC62H60N6Ag4F6O6P4S6: N, 4.55; C, 40.32; H, 3.27;
1
S, 10.42. Found: N, 4.73; C, 40.51; H, 3.56; S, 10.56. H NMR (300
MHz, CDCl3, 25 °C, TMS): δ ) 7.7-7.2 (m, 40H; Ph), 3.97 (m, br,
8H; -CH2-), 1.29 (t, br, 12H; -CH3). 31P{1H} NMR (161.98 MHz,
CDCl3, 25 °C, H3PO4): δ ) 14.6 (s). ESI-MS [CH2Cl2 solution; m/z
(rel int., formula)]: 1107.7 (12%, [Ag2{Ag(EtSNS)}3]2+), 1697.9
(100%, [Ag2{Ag(EtSNS)}2OTf]+.
X-ray Data Collection, Structure Solution, and Refinement for
Compounds 1b, 2a, 3, 4a, 5c, 6a, and 7. Suitable crystals for the
X-ray analysis for complexes 1b, 2a, 3b were obtained by layering
hexane on dichloromethane solutions, for cluster 4a by evaporation of
a CH2Cl2/MeOH solution, for 5c by evaporation of a CH3Cl/hexane
solution, for cluster 6a by evaporation of a toluene/CH2Cl2 solution
and for cluster 7 by evaporation of a THF solution. The intensity data
were collected at room temperature on a Bruker area detector AXS
Smart 100025 [1b, 2a, 4a, 5c, 6a] and on a Philips PW 1100 (3 and 7)
single-crystal diffractometer (using a graphite monochromated Mo KR
radiation, λ ) 0.710 73 Å, for both). Crystallographic and experimental
(c) A solution of complex 2b (133 mg, 0.2 mmol, in 15 mL of THF)
was added to a solution of complex 7 (369 mg, 0.2 mmol, in 15 mL of
THF). Stirring was continued for 10 min. Addition of hexane (40 mL)
afforded cluster 6b as a white powder, purified by crystallization from
a CHCl3/hexane solution.
6a: E.A. (%) calcd for C90H90N9Ag5F12P8S6: N, 5.21; C, 41.67; H,
1
3.25; S, 7.95. Found: N, 5.03; C, 41.70; H, 3.42; S, 8.02. H NMR
(300 MHz, CDCl3, 25 °C, TMS): δ ) 7.2-7.45 (m, 60H; Ph), 3.47
(s, br, 18H; -CH3); 31P{1H} NMR (161.98 MHz, CDCl3, 25 °C, H3-
1
PO4): δ ) 11.8 (s), -143.4 (sept, J(P,F) ) 712 Hz; PF6).
9
J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006 875

A R T I C L E S
Pattacini et al.
details for the structures are summarized in Tables 3 and 4. Bruker
SADABS software [1b, 2a, 4a, 5c, 6a; maximum and minimum
280045 (3), CCDC-256439 (4a), CCDC-280046 (5c), CCDC-280047
(6a), and CCDC-280048 (7) contain the supplementary crystallographic
data for this paper that can be obtained free of charge from the Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_re-
quest/cif. The CIF files are also included in the Supporting Information.
26
transmission coefficient values: 1.000 and 0.788 (1b), 1.000 and 0.586
(2a), 1.000 and 0.680 (4a), 1.000 and 0.741 (5c), 1.000 and 0.946 (6a)],
and psi-scan methods27 [3 and 7, maximum and minimum transmission
coefficient values: 1.000 and 0.388, 1.000 and 0.610, respectively]
were used for the absorption correction. The structures were solved by
direct methods and refined by full-matrix least-squares procedures
Acknowledgment. We thank Dr. Efstathia E. Sakellariou
(National Chemistry Lab., Athens, Greece) for the help in
preparing the manuscript; Dr. Enrico Cavalli (Dipartimento di
Chimica Generale ed Inorganica, Chimica Analitica, Chimica
Fisica, University of Parma, Italy) for the collection of the
emission spectra of complex 4b, and Ministero dell′Istruzione,
dell′Universita` e della Ricerca for financial support.
(based on Fo , SHELX-97)28 first with isotropic thermal parameters
2
and then with anisotropic thermal parameters in the last cycles of
refinement for all the non-hydrogen, except those of the solvent
molecules for 6a. The hydrogen atoms were introduced into the
geometrically calculated positions and refined riding on the corre-
sponding parent atoms, except those bound to solvent molecules. In
2a the ethyl groups were found disordered in two positions with equal
occupancy factors. CCDC-256438 (1b), CCDC-280044 (2a), CCDC-
Supporting Information Available: X-ray crystallographic
data in CIF format; Ortep diagrams with thermal ellipsoids; a
1
discussion of the HMeSNS and H2MeSNS H NMR spectra;
1
the emission spectra of cluster 4a and a series of H NMR
(25) Sheldrick, G. M. SADABS; Bruker Analytical X-ray Systems, Madison,
WI, 1999.
spectra recorded in the temperature range 298-230 K. This
material is available free of charge via the Internet at
http://pubs.acs.org.
(26) SAINT Software Users Guide; SMART Software Users Guide; Bruker
Analytical X-ray Systems: Madison, WI, 1999.
(27) Ugozzoli, F. DIFAU-92.
(28) Sheldrick, M. SHELXL-97, Program for crystal structure refinement;
University of Go¨ttingen: Germany, 1997.
JA0554110
9
876 J. AM. CHEM. SOC. VOL. 128, NO. 3, 2006