Cyclopentadienyl ruthenium(II) dithiocarbamate complexes: Crystal structures of [CpRu(PPh3)(S2CNPr2)] and [CpRu(PPh3)(S2CNMeBu)]

Article abstract of DOI:10.1016/j.ica.2005.08.032

Thermolysis of [CpRuCl(PPh₃)₂] and NaS ₂CNPr₂ or NaS₂CNMeBu in methanol affords the ruthenium(II) dithiocarbamate complexes, [CpRu(PPh₃)(S ₂CNPr₂)] and [CpRu(PPh₃)(S₂CNMeBu)], which have been crystallographically characterized. A similar treatment of two equivalents of [CpRuCl(PPh₃)₂] with the bis(dithiocarbamate) ligand derived from 1,3-homopiperazine affords [{CpRu(PPh₃)}₂(μ-S₂CNC₅H ₁₀NCS₂)].

Full text of DOI:10.1016/j.ica.2005.08.032

Inorganica Chimica Acta 359 (2006) 1018–1022
www.elsevier.com/locate/ica
Note
Cyclopentadienyl ruthenium(II) dithiocarbamate complexes:
Crystal structures of [CpRu(PPh3)(S2CNPr2)] and
[CpRu(PPh3)(S2CNMeBu)]
*
Graeme Hogarth , Simon Faulkner
Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ, UK
Received 27 July 2005; accepted 16 August 2005
Available online 11 November 2005
Ruthenium and Osmium Chemistry Topical Issue
Abstract
Thermolysis of [CpRuCl(PPh3)2] and NaS2CNPr2 or NaS2CNMeBu in methanol affords the ruthenium(II) dithiocarbamate com-
plexes, [CpRu(PPh3)(S2CNPr2)] and [CpRu(PPh3)(S2CNMeBu)], which have been crystallographically characterized. A similar treat-
ment of two equivalents of [CpRuCl(PPh3)2] with the bis(dithiocarbamate) ligand derived from 1,3-homopiperazine affords
[{CpRu(PPh3)}2(l-S2CNC5H10NCS2)].
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Dithiocarbamate; Ruthenium; Phosphine; Cyclopentadienyl; Homopiperazine
1. Introduction
to three of the most ubiquitous and best understood ligands
in coordination chemistry, potentially allowing for a wide
range of variants and thus specific tuning of both chemical
and physical properties. Such complexes are reportedly easy
to prepare from dithio carbamate salts and [CpRuCl(PPh3)2]
[3–6]. Shaver and co-workers [7] have also recently prepared
complexes, [CpRu(PPh3)(S2CNR1R2)] (R1 = Si-i-Pr3, R2 =
Ph, p-tol, 1-naphth; R1 = H, R2 = Ph, 1-naphth), with aryl-
substituents on the dithiocarbamate from the insertion of
arylisothiocyanates into the ruthenium–sulfur bonds of
[CpRu(PPh3)2(SSi-i-Pr3)] and [CpRu(PPh3)2(SH)]. This was
of interest to us as it suggested the potential preparation
and likely enhanced stability of materials containing ruthe-
nium(II) centres linked via aryl bis(dithiocarbamate) ligands
which might allow for a level of electronic communication
between the metal centres.
Dithiocarbamatesareversatileligands,capableofforming
complexes with all the transition elements and able to stabi-
lize most in a range of oxidation states [1]. The first ruthenium
dithiocarbamate complexes, [Ru(S2CNR2)3], were prepared
in the 1930s [2] and in the intervening years dithiocarbamates
have been shown to stabilize this element with a wide variety
of co-ligands in oxidation states +1 to +4. One of the attrac-
tive features of ruthenium dithiocarbamate chemistry is the
extensive redox chemistry that they often show, the +2/+3
couple being reversible in a wide range of systems. This
seemed attractive to us as we hoped to generate multimetallic
arrays based on polyfunctional dithiocarbamate ligands and
investigate their redox properties with the aim of preparing
new materials with novel physical properties.
Anattractive startingpointforthisprogramwouldappear
to be ruthenium(II) complexes, [CpRu(PR3)(S2CNR2)].
Here, the pseudo-octahedral ruthenium(II) centre is bound
2. Results and discussion
*
Thermolysis of a methanol solution of [CpRuCl(PPh3)2]
Corresponding author. Fax: +44 171 380 7463.
E-mail address: g.hogarth@ucl.ac.uk (G. Hogarth).
and commercially available NaS2CNMe2 Æ 3H2O for
0020-1693/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.08.032

G. Hogarth, S. Faulkner / Inorganica Chimica Acta 359 (2006) 1018–1022
1019
30 min afforded the known bright orange complex
[CpRu(PPh3)(S2CNMe2)] in 81% yield [6]. The work-up
in this instance was very simple, removal of NaCl and
PPh3 being accomplished after washing successively with
water and methanol. In order to extend this series of com-
plexes we applied the same methodology with in situ gener-
ated NaS2CNPr2 and NaS2CNMeBu. In both instances,
however, reactions were slower, taking place over 24 h,
and work-up more complicated. The latter seems to result
from the initial formation of oily orange solids which show
appreciable solubility in methanol, thus making removal of
the phosphine more difficult. An attempt to convert the
phosphine into a salt, upon addition of dilute HCl, lead
only to the formation of purple solids with loss of the
expected ruthenium products. The complexes [CpRu(PPh3)-
(S2CNPr2)] and [CpRu(PPh3)(S2CNMeBu)] were eventu-
ally isolated in 62% and 51% yields, respectively, after
extraction of the crude products into dichloromethane fol-
lowed by precipitation with light petroleum. Spectroscopic
and analytical data supported the proposed formulations
and in order to confirm this, crystallographic studies were
carried out on both, the results of which are summarized
in Figs. 1 and 2, Table 1.
and [CpRu(PPh3)(S2CNMeBu)] are as expected. The ruthe-
nium(II) centre adopts a pseudo-octahedral coordination
geometry with the small bite-angle dithiocarbamate [S–Ru–
S 71.83(2)–72.00(3)ꢁ] lying at an approximate right angles
[P–Ru–S 90.92(2)–95.79(2)ꢁ] to the phosphine. The dithio-
carbamate binds approximately symmetrically [Ru–S
˚
2.3779(8)–2.4014(6) A] and in both structures the substitu-
ents are orientated towards the phosphine.
As noted in Section 1, Shaver and co-workers [7] have
prepared complexes of this type upon insertion of arylis-
othiocyanates into [CpRu(PPh3)2(SH)]. Most interestingly,
when 1,4-phenylenediisothiocyanate was used with two
equivalents of [CpRu(PPh3)2(SH)] the dithiocarbamate-
bridged product, 1,4-[{CpRu(PPh3)}2(l-S2CNHC6H4-
NHCS2)] was cleanly formed, which showed good stability,
being characterized by X-ray crystallography. Further, in
recent work we have prepared a number of binuclear com-
plexes in which the metal centres are linked via piperazine
bis(dithiocarbamate) ligand [9]. Hence, it seemed that such
dithiocarbamate-bridged complexes should be realistic tar-
gets and in order to test out this, the bis(dithiocarbamate)
derived from 1,3-homopiperazine was generated in situ and
reacted with two equivalents of [CpRuCl(PPh3)2]. A very
slow reaction took place over 48 h in refluxing methanol
to give after work-up dithiocarbamate-bridged [{CpRu-
(PPh3)}2(l-S2CNC5H10NCS2)] as a bright orange solid in
44% yield. Characterization was made on the basis of ana-
lytical and spectroscopic features, with all attempts to pro-
duce crystals suitable for crystallography proving futile.
S
S
S
S
Pr
Pr
Me
Bu
C
N
C
N
Ru
Ru
Ph3P
Ph3P
1
The H NMR spectrum was quite complex as might be
expected but importantly, a single cyclopentadienyl reso-
nance was clearly observed. The protons of the homopiper-
azine unit appear in two groups; a complex multiple
between d 3.39 and 3.26 assigned to the nitrogen-bound
methylene groups and a second multiplet between d 1.57
Somewhat surprisingly, only one simple complex of this
type has previously been crystallographically characterized;
structures of two polymorphs of [CpRu(PPh3)(S2CNMe2)]
beingreported [6,8]. Keyfeatures of[CpRu(PPh3)(S2CNPr2)]
Fig. 1. Molecular structure of [CpRu(PPh3)(S2CNPr2)].

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G. Hogarth, S. Faulkner / Inorganica Chimica Acta 359 (2006) 1018–1022
Fig. 2. Molecular structure of [CpRu(PPh3)(S2CNMeBu2)].
and 1.52 assigned to the central methylene unit. The latter
is very complex but clearly associated with two overlapping
multiplets being assigned to axial and equatorial protons.
ing that ruthenium has been oxidized to +3 state. A UV–
Vis spectrum revealed a strong transition at 550 nm, as
compared to that at 355 nm found in [CpRu(PPh3)
(S2CNPr2)]. A similar intense absorption at 550 nm was
also observed for the purple product of HCl addition to
[CpRu(PPh3)(S2CNPr2)] (see above) and the precise nature
of this is still under investigation.
In conclusion, we have shown that while complexes of
the type [CpRu(PR3)(S2CNR2)] are readily prepared, long
reaction times, difficulties in product purification and long
term stability does not make them the attractive targets
that we had anticipated. In contrast we have recently found
that cationic ruthenium(II) complexes, [Ru(diphos-
phine)2(S2CNR2)]+, are more readily prepared and purified
[9].
S
PPh3
S
S
N
C
Ru
Ru
N
C
S
Ph3P
While the complexes described above are quite stable in
the solid state, in solution in the presence of oxygen they
slowly decompose. When a sample of [CpRu(PPh3)-
(S2CNPr2)] in CDCl3 was monitored by NMR over a per-
iod two weeks a gradual darkening of the sample took
place with concomitant formation of Ph3P@O, as shown
by 31P NMR spectroscopy. To date we have been unable
to determine the fate of the organometallic fragment.
While the phosphine oxide is clearly visible in the 1H
NMR spectrum, no other clear peaks are observed suggest-
3. Experimental
3.1. Synthesis of [CpRu(PPh3)(S2CNPr2)] [6]
A methanol solution (20 cm3) of NaS2CNMe2 Æ 3H2O
(84 mg, 0.59 mmol) and [CpRuCl(PPh3)2] (0.52 g, 0.70
Table 1
˚
Selected bond lengths (A) and bond angles (ꢁ) for [CpRu(PPh3)(S2CNR2)]
R2
Ru–S
Ru–P
C@N
S–Ru–S
72.00(3)
P–Ru–S
Pr2
2.3957(8)
2.3779(8)
2.4014(6)
2.3971(6)
2.397(3)
2.394(3)
2.394(2)
2.387(2)
2.2735(7)
1.336(5)
95.09(3)
92.01(3)
95.79(2)
90.92(2)
95.18(9)
98.82(9)
95.02(9)
92.56(9)
Me/Bu
2.2782(6)
2.285(2)
2.269(2)
1.328(3)
1.354(10)
1.377(7)
71.83(2)
71.88(9)
71.69(8)
8
Me2
SiiPr3/Naphth7

G. Hogarth, S. Faulkner / Inorganica Chimica Acta 359 (2006) 1018–1022
1021
mmol) was refluxed for 30 min. Removal of volatiles under
3.4. Synthesis of [{CpRu(PPh3)}2(l-S2CNC5H10NCS2)]
reduced pressure gave an orange solid which was washed
successively with water (ca. 2 · 10 cm3) and methanol (ca.
2 · 10 cm3) to give [CpRu(PPh3)(S2CNMe2)] [6] as a bright
To 1,3-homopiperazine (100 mg, 1.00 mmol) in metha-
nol (10 cm3) was added NaOH (100 mg, 2.50 mmol) and
CS2 (152 mg, 2.00 mmol). After strirring for 1 h,
[CpRuCl(PPh3)2] (400 mg, 0.56 mmol) in methanol
(20 cm3) was added and the mixture was refluxed for 2 d.
Volatiles were removed under reduced pressure to leave
an orange solid which was extracted in dichloromethane
(ca. 20 cm3), filtered and dried over MgSO4. Removal of
volatiles under reduced pressure gave an orange solid
which was washed with light petroleum (ca. 20 cm3), taken
up in a minimum volume of dichloromethane and light
petroleum added which lead to the precipitation of
[{CpRu(PPh3)}2(l-S2CNC5H10NCS2)] as an orange solid
(0.15 g, 44%). 1H NMR (CDCl3) d 7.54–7.26 (m, 30H,
Ar), 4.39 (s, 10H, Cp), 3.39–3.26 (m, 8H, NCH2), 1.57–
1.52 (m, 2H, CH2); 31P NMR (CDCl3) d 38.4 (s); IR(KBr)
m/cmÀ1 1589m, 1481m, 1419m, 1218m, 1180m, 918m,
694w, 532w; mass spectrum (FAB) m/z 1107 (M+ + 1);
Anal. Calc. for C53H50N2S4P2Ru2 Æ 11/2CH2Cl2: C, 53.45;
H, 3.54; N, 2.29. Found: C, 53.58; H, 4.34; N, 2.18%.
1
orange solid (0.26 g, 81%). H NMR (CDCl3) d 7.34–7.08
(m, 15H, Ar), 4.36 (s, 5H, Cp), 2.75 (s, 6H, Me); 31P
NMR (CDCl3) d 38.1 (s); IR(KBr) m/cmÀ1 1558s, 1386m,
1259w, 1153w, 1085m, 1068w, 983w, 831w, 796w, 744m,
694s, 586w, 520s, 499m, 462w, 422w; mass spectrum
(FAB) m/z 549 (M+ + 1).
3.2. Synthesis of [CpRu(PPh3)(S2CNPr2)]
To a hot methanol solution (5 cm3) of NaS2CNPr2
(ca. 0.75 mmol) [generated from NaOH (37 mg, 0.93
mmol), Pr2NH (74 mg, 0.73 mmol) and CS2 (57 mg,
0.75 mmol)] was added dropwise a methanol solution
(15 cm3) of [CpRuCl(PPh3)2] (0.50 g, 0.70 mmol). The
resulting solution was refluxed for 24 h after which the
solvent was removed under reduced pressure to leave
an oily orange solid. This was extracted in dichlorometh-
ane (ca. 20 cm3), filtered and dried over MgSO4.
Removal of volatiles under reduced pressure again gave
an orange oil which was washed with light petroleum
(ca. 20 cm3) to afford after drying an oily orange solid.
This was taken up in a minimum volume of dichloro-
methane and light petroleum added which lead to the
precipitation of [CpRu(PPh3)(S2CNPr2)] as an orange
solid (0.26 g, 62%). Orange crystals suitable for crystal-
lography resulted upon slow diffusion of light petroleum
3.5. X-ray data collection and solution
Single crystals were mounted on glass fibres and all geo-
metric and intensity data were taken from these samples
using a Bruker SMART APEX CCD diffractometer using
graphite-monochromated Mo Ka radiation (k =
˚
0.71073 A). Data reduction was carried out with SAINT
1
into a concentrated dichloromethane solution. H NMR
PLUS and absorption correction applied using the pro-
gram SADABS. Structures were solved by direct methods
and developed using alternating cycles of least-squares
refinement and difference-Fourier synthesis. All non-
hydrogen atoms were refined anisotropically. Hydrogens
were generally placed in calculated positions (riding
model). Structure solution used SHELXTL PLUS V6.10 pro-
gram package.
(CDCl3) d 7.51–7.24 (m, 15H, Ar), 4.32 (s, 5H, Cp),
3.18 (t, J 7.0, 4H, NCH2), 1.38 (m, 4H, CH2), 0.77 (t,
J 7.0, 6H, Me); 31P NMR (CDCl3) d 37.2 (s); IR(KBr)
m/cmÀ1 1481s, 1427m, 1365m, 1303m, 1242m, 1149m,
1095m, 995m, 794w, 694s, 532s, 432w; mass spectrum
(FAB) m/z 605 (M+ + 1); Anal. Calc. for C30H34
NS2PRu: C, 59.57; H, 5.67; N, 2.32. Found: C, 60.85;
H, 5.59; N, 1.88%.
Crystallographic data for [CpRu(PPh3)(S2CNPr2)]:
T = 293 2 K, orange block, dimensions 0.24 · 0.16 ·
0.15 mm, monoclinic, space group P21/n, a = 14.9462(8),
3.3. Synthesis of [CpRu(PPh3)(S2CNMeBu)]
˚
b = 10.2897(6), c = 19.7018(11) A, b = 106.9020(10)ꢁ,
3
˚
Following the procedure outlined above, NaS2CNMeBu
(ca. 0.75 mmol) and [CpRuCl(PPh3)2] (0.50 g, 0.70 mmol)
were heated in methanol (20 cm3), to provide after work-
up, [CpRu(PPh3)(S2CNMeBu)] as a yellow-orange solid
(0.20 g, 51%). Small yellow crystals were grown upon slow
evaporation of a dichloromethane-light petroleum solu-
V = 2899.1(3) A ,
Z = 4,
F(000)
1248,
dcalc =
1.386 g cmÀ3, l = 0.759 mmÀ1. 25025 reflections were col-
lected, 6916 unique [R(int) = 0.0169] of which 6255 were
observed [I > 2.0r(I)]. At convergence, R1 = 0.0431,
wR2 = 0.1131 [I > 2.0r(I)] and R1 = 0.0474, wR2 = 0.1165
(all data), for 316 parameters. Crystallographic data has
been deposited with the Cambridge Crystallographic Data
Centre, CCDC No. 277299.
1
tion. H NMR (CDCl3) d 7.56–7.27 (m, 15H, Ar), 4.37
(s, 5 H, Cp), 3.30 (m, 2H, NCH2), 3.15 (m, 2H, CH2),
2.80 (s, 3H, NMe), 1.26 (m, 2H, CH2), 0.88 (t, J 7.0, 3H,
Me); 31P NMR (CDCl3) d 37.0 (s); IR(KBr) m/cmÀ1
1651m, 1481m, 1434m, 1396m, 1257m, 1226m, 1095m,
1026m, 802m, 694w, 748w, 524w; mass spectrum (FAB)
m/z 591 (M+ + 1); Anal. Calc. for C29H32NS2PRu Æ
1/2CH2Cl2: C, 57.56; H, 5.40; N, 2.28. Found: C, 56.01;
H, 6.11; N, 2.24%.
Crystallographic data for [CpRu(PPh3)(S2CNMeBu)]:
T = 150 2 K, yellow block, dimensions 0.08 · 0.06 ·
ꢀ
0.05 mm, triclinic, space group P1, a = 10.4423(7), b =
˚
11.1247(8), c = 11.5011(8) A, a = 97.1030(10), b =
3
˚
106.9020(10), c = 95.8550(10), V = 1315.61(16) A , Z = 2,
F(000) 608, dcalc = 1.491 g cmÀ3, l = 0.834 mmÀ1. 11698
reflections were collected, 6037 unique [R(int) = 0.0202] of

1022
G. Hogarth, S. Faulkner / Inorganica Chimica Acta 359 (2006) 1018–1022
[3] A. Coto, M.J. Tenorio, M.C. Puerta, P. Valerga, Organometallics 17
(1998) 4392.
[4] T. Wilczewski, M. Bochenska, J.F. Biernat, J. Organomet. Chem. 215
(1981) 87.
[5] L.B. Reventos, A.G. Alonso, J. Organomet. Chem. 309 (1986) 179.
[6] Q.J. McCubbin, F.J. Stoddart, T. Welton, A.J.P. White, D.J. Williams,
Inorg. Chem. 37 (1998) 3753.
which 5447 were observed [I > 2.0r(I)]. At convergence,
R1 = 0.0316, wR2 = 0.0734 [I > 2.0r(I)] and R1 = 0.0364,
wR2 = 0.0758 (all data), for 307 parameters. Crystallo-
graphic data has been deposited with the Cambridge Crys-
tallographic Data Centre, CCDC No. 277300.
[7] I. Kova´cs, A.-M. Lebuis, A. Shaver, Organometallics 20 (2001) 35.
[8] A.W. Cordes, M. Draganjac, Acta Crystallogr., Sect. C 44 (1988)
363.
References
[1] G. Hogarth, Prog. Inorg. Chem. 53 (2005) 71.
[2] L. Malatesta, Gazz. Chim. Ital. 68 (1938) 195.
[9] G. Hogarth, D. Solanki, J.W.E. Wilton-Ely, Eur. J. Inorg. Chem.
4027.