Multifunctional dithiocarbamates as ligands towards the rational synthesis of polymetallic arrays: An example based on a piperizine-derived dithiocarbamate ligand

Article abstract of DOI:10.1002/ejic.200500430

The zwitterionic piperazine-derived dithiocarbamate complex [(dppm) ₂Ru(S₂CNC₄H₈NCS₂)] has been prepared and utilised in the synthesis of multimetallic arrays incorporating a wide range of transition metal centres. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.

Full text of DOI:10.1002/ejic.200500430

SHORT COMMUNICATION
Multifunctional Dithiocarbamates as Ligands Towards the Rational Synthesis
of Polymetallic Arrays: An Example Based on a Piperizine-Derived
Dithiocarbamate Ligand
James D. E. T. Wilton-Ely,*[a] Dina Solanki,[a] and Graeme Hogarth*[a]
Keywords: Dithiocarbamates / Piperazine / Multimetallic arrays / Ruthenium complexes / Coordination chemistry
The zwitterionic piperazine-derived dithiocarbamate com-
plex [(dppm)2Ru(S2CNC4H8NCS2)] has been prepared and
utilised in the synthesis of multimetallic arrays incorporating
a wide range of transition metal centres.
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2005)
molecule containing two secondary amine centres. Such
species react with CS2 to afford a zwitterionic product,[5,6]
whereby one of the amines acts as a nucleophile and the
second as a base. Under the right conditions, only small
amounts of the symmetrical double salt [S2CN(X)-
NCS2][H2N(X)NH2] (X = spacer) are formed, which is a
key advantage of this approach as this allows one end of the
amine to be extended selectively by reaction with carbon
disulfide. Reaction of the zwitterionic product,
[H2NC4H8NCS2], with a metal complex results in the for-
mation of a new metal-amine compound, which in turn can
react with further CS2 to generate a new metal-containing
dithiocarbamate ligand. In this manner multimetallic arrays
can be constructed in a modular, step-wise fashion
(Scheme 1). This approach, which is demonstrated by the
reactions shown in Scheme 2, can be extended using tri- and
tetradentate amines to incorporate further dimensionality.
As a proof of concept, we have used cheap and commer-
cially available piperazine in order to demonstrate the ease
and potential of such an approach. We have used the ruthe-
nium() complex cis-[RuCl2(dppm)2][7] to provide a cis-
Ru(dppm)2 moiety as the initial metal fragment. This choice
was based on our observation that cis-[RuCl2(dppm)2]
reacts cleanly with a wide range of dithiocarbamate salts to
afford the cations [Ru(S2CNR2)(dppm)2]+ in high yield.
These complexes are easily characterised by a range of spec-
troscopic techniques, of which 31P NMR spectroscopy
proves particularly useful.
Introduction
Dithiocarbamates are extremely versatile ligands which
form complexes with all the transition metals, leading to
the stabilisation of a wide range of oxidation states.[1] Since
their complexes are easily prepared and manipulated, a
wide range of applications have been developed in areas as
diverse as materials science, medicine and agriculture.
Given this versatility, their well-defined architecture and the
bountiful metal-centred electrochemistry shown by these
complexes,[2] it is surprising that they have found little use
in the burgeoning area of supramolecular chemistry. Re-
cently, however, Beer and co-workers have started to ad-
dress this issue, preparing a range of exciting new supramo-
lecular architectures based on multifunctional dithiocar-
bamate ligands, many of which show interesting structural-
redox properties.[3] It is clear from this work that dithiocar-
bamates have the potential to be utilised to a far greater
extent than found currently in the areas of supramolecular
chemistry and materials science. With this in mind we have
focused our initial efforts on the development of multiden-
tate dithiocarbamate ligands for the synthesis of multimet-
allic arrays. Such arrays could be one, two or three-dimen-
sional in nature, the dimensionality being easily controlled
as a function of the properties of both the metal and ligand.
We envisage that these materials will show novel physical
properties in their own right and will be explored as precur-
sors to the synthesis of well-defined nanoparticulates in a
manner developed extensively by O’Brien and co-workers.[4]
Addition of CS2 to piperazine in water results in the for-
mation of the zwitterion, H2NC4H8NCS2 (1), which is read-
ily isolated (Scheme 2). Addition of one equivalent of cis-
[RuCl2(dppm)2] to this zwitterion, followed by an excess of
NaBF4 affords [(dppm)2Ru(S2CNC4H8NH2)][BF4]2 (2) in
high yield,[8] which is then converted into the new complex,
[(dppm)2Ru(S2CNC4H8NCS2)] (3), upon sequential ad-
dition of two equivalents of base and CS2. The latter is a
Results and Discussion
A simple strategy for the synthesis of multimetallic wires
is outlined below (Scheme 1). It centres on the use of a
[a] Department of Chemistry, University College London,
20 Gordon Street, London, WC1H 0AJ, UK
E-mail: j.wilton-ely@ucl.ac.uk
g.hogarth@ucl.ac.uk
Eur. J. Inorg. Chem. 2005, 4027–4030
DOI: 10.1002/ejic.200500430
© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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J. D. E. T. Wilton-Ely, D. Solanki, G. Hogarth
SHORT COMMUNICATION
Scheme 1. (i) CS2; (ii) M1X; (iii) 2NEt3, CS2; (iv) M2X; (v) M1X2; (vi) 4NEt3, 2CS2; (vii) M2X2.
Scheme 2. [M] = Ru(dppm)2;L = PPh3; R = C6H4Me-4; (i) CS2; (ii) cis-[RuCl2(dppm)2], 2NaBF4; (iii) 2NEt3, CS2; (iv) 2NEt3, 2CS2; 2cis-
[RuCl2(dppm)2]; (v) [Os(CH=CHR)Cl(CO)(BTD)L2] (BTD = 2,1,3-benzothiadiazole); (vi) ClAuL; (vii) [Pd(C6H4CH2NMe2)Cl]2; (viii)
Ni(OAc)2; (ix) Cu(OAc)2.
key building block and can be considered to be a metallo- tathesis. In order to confirm the bridging nature of the di-
dithiocarbamate. In order to demonstrate its utility we thiocarbamate, a crystallographic study of 4 was performed
treated this compound with a second equivalent of cis- (Figure 1).[10] The bridging dithiocarbamate mode found in
[RuCl2(dppm)2] to afford (after salt metathesis) the binu- 4 is rare but not unique; Shaver and co-workers having re-
clear complex [(dppm)2Ru(S2CNC4H8NCS2)Ru(dppm)2]- cently prepared a related diruthenium complex, [Cp(PPh3)-
[BF4]2 (4).[9] The same complex is also produced in a one- Ru(S2CNC6H4NCS2)Ru(PPh3)Cp], from the unusual reac-
step reaction upon addition of Na2[S2CNC4H8NCS2] to tion of two equivalents of [CpRu(PPh3)2SH] with para-
two equivalents of cis-[RuCl2(dppm)2] followed by salt me- phenylenediisothiocyanate.[11] A dinuclear tin complex has
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Eur. J. Inorg. Chem. 2005, 4027–4030

Multifunctional Dithiocarbamates as Ligands for Polymetallic Arrays
SHORT COMMUNICATION
Figure 1. Structure of the cation in [{Ru(dppm)2}2(S2CNC4H8NCS2)][BF4]2 (4).
also been reported.[6a] Zwitterion 3 can be employed to pre-
pare a wide range of dithiocarbamate-bridged binuclear
metal complexes as we have illustrated with the formation
of 5–7,[9] in which osmium,[8] gold and palladium centres,
respectively, are coordinated using suitable reagents.
In each of the cases described above, the added metal
centre binds only a single dithiocarbamate ligand. Trimetal-
lic units based on two bidentate dithiocarbamate ligands
result from the addition of metals with two dithiocarbam-
ate-binding sites. In order to illustrate this, we treated 3 with
nickel and copper acetate to quantitatively afford [{(dppm)2-
Ru(S2CNC4H8NCS2)}2M][BF4]2 [M = Ni (8), Cu (9)]
(Scheme 2).[9] These examples illustrate the ease of incorpo-
ration of diamagnetic and paramagnetic centres which show
well-defined and understood redox properties into these ar-
rays. We have extended this strategy to the formation of
tetranuclear complexes upon coordination of zwitterion 3
to FeIII, CoIII and LaIII centres and are currently using
methyl-substituted piperazines to prepare chiral materials.
We have also begun work using 1,4,7-triazacyclononane
and 1,4,8,11-tetraazacyclotetradecane (cyclam) as a build-
ing block to prepare multidentate dithiocarbamate ligands
with the aim of preparing magnetic 2D sheet-like structures
with large cavities.
studentship (D. S.). We also thank the Department of Chemistry,
UCL, The Central Research Fund, the UCL Graduate School and
Cognis Ltd for funding and Johnson Matthey Ltd for a generous
loan of ruthenium salts.
[1] G. Hogarth, Prog. Inorg. Chem. 2005, 53, 71–561.
[2] A. M. Bond, R. L. Martin, Coord. Chem. Rev. 1984, 54, 23–98.
[3] a) P. D. Beer, N. G. Berry, A. R. Cowley, E. J. Hayes, E. C.
Oates, W. W. H. Wong, Chem. Commun. 2003, 2408–2409; b)
W. W. H. Wong, D. Curiel, A. R. Cowley, P. D. Beer, Dalton
Trans. 2005, 359–364; c) P. D. Beer, A. G. Cheetham, M. G. B.
Drew, O. D. Fox, E. J. Hayes, T. D. Rolls, Dalton Trans. 2003,
603–611; d) P. D. Beer, N. Berry, M. G. B. Drew, O. D. Fox,
M. E. Padilla-Tosta, S. Patell, Chem. Commun. 2001, 199–200;
e) M. E. Padilla-Tosta, O. D. Fox, M. G. B. Drew, P. D. Beer,
Angew. Chem. Int. Ed. 2001, 40, 4235–4239; f) O. D. Fox,
M. G. B. Drew, P. D. Beer, Angew. Chem. Int. Ed. 2000, 39,
135–140.
[4] a) T. Trindade, P. O’Brien, J. Mater. Chem. 1996, 6, 343–347;
b) M. Green, P. O’Brien, Chem. Commun. 1999, 2235–2241; c)
T. Trindade, P. O’Brien, N. L. Pickett, Chem. Mater. 2001, 13,
3843–3858.
[5] J. Dunderdale, T. A. Watkins, Chem. Ind. (London) 1956, 174–
175 and references cited therein.
[6] Some metal complexes of piperazine dithiocarbamates have
been reported: a) K. S. Siddiqi, F. R. Zaidi, S. A. A. Zaidi,
Synth. React. Inorg. Met.-Org. Chem. 1980, 10, 569–578; b) G.
Marcotrigiano, G. C. Pellacani, C. Preti, G. Tosi, Bull. Chem.
Soc. Jpn. 1975, 48, 1018–1020; c) A. Hulanicki, L. Shishkova,
Chem. Anal. (Warsaw) 1965, 10, 837–845.
Conclusions
[7] B. P. Sullivan, T. J. Meyer, Inorg. Chem. 1982, 21, 1037–1040.
[8] Representative syntheses: a) Zwitterion 1 (26 mg, 0.161 mmol)
and NaBF4 (23 mg, 0.210 mmol) were suspended in methanol
(20 mL) and cis-[RuCl2(dppm)2] (100 mg, 0.106 mmol) added
as a dichloromethane (10 mL) solution. The reaction was
heated at reflux for 10 min and then stirred for 2 h. All solvent
was removed and the residue was taken up in a minimum
amount of dichloromethane and filtered through diatomaceous
earth. Addition of ethanol (30 mL) and reduction of solvent
volume by rotary evaporation yielded complex 2 (93 mg, 73%).
b) Complex 2 (100 mg, 0.083 mmol) was dissolved in dichloro-
methane (10 mL) and treated with NEt3 (5 drops, excess) and
stirred for 5 min. Carbon disulfide (3 drops, excess) was added
and the reaction stirred for 5 min to generate complex 3.
The piperazine-based dithiocarbamate complexes re-
ported here demonstrate how the construction of multimet-
allic arrays can be achieved in a controlled, stepwise man-
ner. This approach has great potential for the fabrication of
materials incorporating a wide range of metal centres whose
properties (e. g., redox, CVD, host-guest chemistry) can be
tailored.
Acknowledgments
[Os(CH=CHC6H4Me-4)Cl(CO)(BTD)(PPh3)2]
(86 mg,
We gratefully acknowledge the Ramsay Memorial Trust for provi-
sion of a Fellowship (J. D. E. T. W.-E.) and the EPSRC for a Case
0.083 mmol) was added as a dichloromethane solution (10 mL)
and the reaction was stirred for 1 h. All solvent was removed
Eur. J. Inorg. Chem. 2005, 4027–4030
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© 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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J. D. E. T. Wilton-Ely, D. Solanki, G. Hogarth
SHORT COMMUNICATION
and the residue was taken up in a minimum amount of dichlo-
romethane and filtered through diatomaceous earth. Addition
of ethanol (30 mL) and reduction of solvent volume by rotary
evaporation yielded complex 5 (121 mg, 71%).
[M]+. C74H67AuBF4N2P5RuS4 (1652.33): calcd. C 53.8, H 4.1,
N 1.7; found C 54.0, H 4.0, N 1.6. 7: IR (KBr/nujol): ν = 1574,
˜
1308, 1278, 1219, 1157, 1055 [ν(BF)], 907, 849 cm–1. 31P{1H}
NMR (CDCl3): δ = –4.2, –16.9 (2 t, JPP = 34.2 Hz, dppm)
1
[9] Characterisation data for new complexes. 1: IR (KBr/nujol): ν
ppm. H NMR (CDCl3): δ = 2.92 [s, 6 H, CH3], 3.71, 3.79 (2
˜
= 1601 [ν(CS)], 1580, 1265, 1227, 1207, 1134, 1119, 1015, 966,
897 cm–1. 1H NMR (CDCl3): δ = 2.88 (m, 4 H, H2CNH2CH2),
4.30 (s, 2 H, NH2), 4.31 [m, 4 H, H2CN(CS2)CH2] ppm.
MS(EI): m/z = 162 [M]+. C5H10N2S2 (162.28): calcd. C 37.0,
H 6.2, N 17.3; found C 37.7, H 6.5, N 17.5. 2: IR (KBr/nujol):
m, 8 H, NC4H8N), 4.01 (s, 2 H, CCH2), 4.64, 4.96 (2 m, 2×2
H, PCH2P), 6.53, 6.94, 7.03, 7.17, 7.31, 7.62 (6 m, 40 H + 4
H, C6H5 + C6H4) ppm. FAB-MS: m/z (abundance) = 1346 (12)
[M]+. C65H64BF4N3P4PdRuS4 0.5CH2Cl2 (1476.16): calcd. C
.
53.3, H 4.4, N 2.9; found C 53.1, H 5.0, N 3.2. 8: IR (KBr/
ν = 1585, 1574, 1312, 1269, 1236, 1190, 1161, 1057 [ν(BF)],
nujol): ν = 1614, 1559, 1308, 1279, 1221, 1192, 1057 [ν(BF)],
˜
˜
918, 849 cm–1. 31P{1H} NMR (CDCl3): δ = –3.8, –17.3 [2 t,
910, 849 cm–1. 31P{1H} NMR (CDCl3): δ = –4.2, –16.8 (2 t,
JPP = 34.5 Hz, dppm) ppm. 1H NMR (CDCl3): δ = 3.58 (m,
16 H, NC4H8N), 4.64, 4.98 (2m, 2×4 H, PCH2P), 6.52, 6.94,
7.03, 7.18, 7.26, 7.38, 7.61 (7 m, 80 H, C6H5) ppm. FAB-MS:
m/z (abundance) = 2271 (9) [M]+. C112H104B2F8N4NiP8Ru2S8
(2444.84): calcd. C 55.0, H 4.3, N 2.3; found C 55.4, H 4.2, N
1
JPP = 34.4 Hz, dppm] ppm. H NMR (CDCl3): δ = 2.35 [br. s,
2 H, NH2], 3.04, 3.88 [2m, 2×4 H, NC4H8N], 4.53, 4.91 [2 m,
2×2 H, PCH2P], 6.48–7.57 [6 m, 40 H, C6H5] ppm. FAB-MS:
m/z
(abundance)
=
1030
(100)
[M]+.
.
C55H53BF4N2P4RuS2 0.5CH2Cl2 (1160.41): calcd. C 57.5, H
4.7, N 2.4; found C 57.8, H 4.6, N 2.5 (this recrystallised mate-
rial was analysed as the deprotonated monotetrafluoroborate
2.2. 9: IR (KBr/nujol): ν = 1585, 1572, 1310, 1279, 1221, 1157,
˜
1057 [ν(BF)], 910, 849 cm–1. 31P{1H} NMR (CDCl3): δ =
–4.2, –16.8 (2t, JPP = 34.3 Hz, dppm) ppm. 1H NMR (CDCl3):
δ = 4.61, 4.96 (2 br. s, 2×4 H, PCH2P), 6.52, 6.93, 7.03, 7.32,
7.62 [5 br. s, 80 H, PC6H5] ppm (NC4H8N not observed due
to effect of paramagnetism). FAB-MS: m/z (abundance) = 2276
(3) [M]+. C112H104B2CuF8N4P8Ru2S8·CH2Cl2 (2534.63): calcd.
C 53.6, H 4.2, N 2.2; found C 53.4, H 4.2, N 2.2.
salt, [dppm Ru(S CNC H NH)]BF ). 4: IR (KBr/nujol): ν =
˜
2
2
4
8
4
1614, 1574, 1310, 1278, 1219, 1057 [ν(BF)], 918, 849 cm–1.
31P{1H} NMR (CDCl3): δ = –4.1, –16.8 [2 t, JPP = 34.2 Hz,
dppm] ppm. 1H NMR (CDCl3): δ = 3.51, 3.62 [2 d, JHH
=
9.5 Hz, 8 H, ax/eq-NC4H8N], 4.56, 4.91 [2 m, 2×4 H, PCH2P],
6.50, 6.93, 7.03, 7.26, 7.38, 7.63 [6 m, 80 H, C6H5] ppm. FAB-
MS: m/z (abundance) = 2063 (20) [M + BF4]+, 1976 (13)
[10] Single crystals of 4 were grown by slow evaporation of a con-
.
[M]+. C106H96B2F8N2P8Ru2S4 CH2Cl2 (2234.68): calcd. C 57.5,
centrated solution of the complex in chloroform. Crystal data
H 4.4, N 1.3; found C 57.3, H 4.6, N 1.3. 5: IR (KBr/nujol):
for
C109H99B2Cl9F8N2P8Ru2S4, M = 2507.71, monoclinic, space
group P21/n, 22.2606(14), 22.2816(14), c =
4:
[{Ru(dppm2(S2CNC4H8NCS2)][BF4]2·3CHCl3,
ν = 1898 [ν(CO)], 1614, 1310, 1217, 1188, 1057 [ν(BF)], 918,
˜
847 cm–1. 31P{1H} NMR (CDCl3): δ = 9.3 [s, PPh3], –4.4,
a
=
b
=
1
–17.1 [2 t, JPP = 34.4 Hz, dppm] ppm. H NMR (CDCl3): δ =
22.5341(14) Å, β = 80.1650(10)°, U = 11012.7(12) Å3, Z = 4, T
= 150(2) K, µ(Mo-Kα) = 0.747 mm–1, Dcalcd. = 1.512 g cm–3,
26374 independent reflections measured, 10556 I Ն 2σ(I), R1
= 0.1020, Rw = 0.1675. Data reduction and refinement were
carried using the SHELXTL PLUS V6.10 program package.
The supplementary crystallographic data for this structure,
CCDC-266476 contains the supplementary crystallographic
data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
2.21 (s, 3 H, CH3), 2.78–3.33 (m br., 8 H, NC4H8N), 4.64, 4.97
(2 m, 2×2 H, PCH2P), 5.59 [d, JHH = 17.1 Hz, 1 H, Hβ], 6.36,
6.81 [(AB)2, JAB = 8.0 Hz, 4 H, C6H4], 6.52, 6.93, 6.96, 7.26,
7.61 [5m, 70 H, C6H5], 8.28 [dt, JHH = 17.1, JHP = 2.6 Hz,
1 H, Hα] ppm. FAB-MS: m/z (abundance) = 1967 (38) [M]+.
.
C
102H91BF4N2OOsP6RuS4 CH2Cl2 (2137.97): calcd. C 57.9, H
4.4, N 1.3; found C 57.7, H 4.5, N 1.3. 6: IR (KBr/nujol): ν =
˜
1585, 1572, 1310, 1277, 1207, 1155, 1055 [ν(BF)], 912,
849 cm–1. 31P{1H} NMR ([D6]acetone): 37.5 [br. s, PPh3],
–3.0, –18.0 [2 t, JPP = 34.5 Hz, dppm] ppm. 1H NMR ([D6]-
acetone): δ = 3.73, 3.92, 4.14, 4.23 (4 m, 8 H, NC4H8N), 4.75,
5.36 (2 m, 2×2 H, PCH2P), 6.69, 7.00, 7.24, 7.40, 7.60, 7.63 (6
m, 55 H, C6H5) ppm. FAB-MS: m/z (abundance) = 1566 (3)
[11] I. Kovács, A.-M. Lebuis, A. Shaver, Organometallics 2001, 20,
35–41.
Received: May 15, 2005
Published Online: August 17, 2005
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Eur. J. Inorg. Chem. 2005, 4027–4030