An unsaturated half-sandwich ruthenium(II) complex containing a dithioimidodiphosphinate ligand

Article abstract of DOI:10.1016/j.ica.2005.04.031

Treatment of [Cp*RuCl₂]_x (Cp* = η⁵-C₅Me₅) with K[N(Ph₂PS) ₂] afforded [Cp*Ru{N(Ph₂PS)₂}Cl] (1). Reduction of 1 with Li[BEt₃H] gave the 16-electron half-sandwich Ru(II) complex [Cp*Ru{N(Ph₂PS)₂}] (2). Complexes 1 and 2 have been characterized by X-ray crystallography. The Ru- Cp*(centroid) and average Ru-S distances in 1 are 1.827 and 2.3833(5) A?, respectively. The corresponding bond distances in 2 are 1.739 and 2.379(1) A?. Treatment of 2 with 2-electron ligands L afforded the adducts [Cp*Ru{N(Ph₂PS)₂}L] (L = CO (3), 2,6-Me ₂C₆H₄NC (4), MeCO₂C≡CCO ₂Me (5)). Oxidation of 2 with tetramethylthiuram disulfide gave the Ru(IV) complex [Cp*Ru{S₂CNMe₂}₂] [N(Ph₂PS)₂] (6). The Ru-Cp*(centroid) and average Ru-S distances in 6 are 1.897 and 2.387(1) A?, respectively.

Full text of DOI:10.1016/j.ica.2005.04.031

Inorganica Chimica Acta 359 (2006) 782–788
www.elsevier.com/locate/ica
An unsaturated half-sandwich ruthenium(II) complex containing a
dithioimidodiphosphinate ligand
*
Wai-Man Cheung, Qian-Feng Zhang, Ian D. Wiliams, Wa-Hung Leung
Department of Chemistry, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, PR China
Received 21 February 2005; accepted 25 April 2005
Available online 13 June 2005
Ruthenium and Osmium Chemistry Topical Issue
Abstract
Treatment of [Cp*RuCl2]x (Cp* = g5-C5Me5) with K[N(Ph2PS)2] afforded [Cp*Ru{N(Ph2PS)2}Cl] (1). Reduction of 1 with
Li[BEt3H] gave the 16-electron half-sandwich Ru(II) complex [Cp*Ru{N(Ph2PS)2}] (2). Complexes 1 and 2 have been characterized
˚
by X-ray crystallography. The Ru–Cp*(centroid) and average Ru–S distances in 1 are 1.827 and 2.3833(5) A, respectively. The cor-
˚
responding bond distances in 2 are 1.739 and 2.379(1) A. Treatment of 2 with 2-electron ligands L afforded the adducts
[Cp*Ru{N(Ph2PS)2}L] (L = CO (3), 2,6-Me2C6H4NC (4), MeCO2C„CCO2Me (5)). Oxidation of 2 with tetramethylthiuram disul-
fide gave the Ru(IV) complex [Cp*Ru{S2CNMe2}2][N(Ph2PS)2] (6). The Ru–Cp*(centroid) and average Ru–S distances in 6 are
˚
1.897 and 2.387(1) A, respectively.
Ó 2005 Elsevier B.V. All rights reserved.
Keywords: Ruthenium; Half-sandwich compound; 16-electron; Sulfur ligand
1. Introduction
Cp* centroid and the RuN2 moiety has been isolated [4].
While unsaturated CpRu(II) complexes stabilized by
nitrogen [2,4,5] and oxygen [2,6,7] donor ligands are well
known, there are few examples of such complexes sup-
ported by sulfur ligands.
Dithioimidophosphinates [N(R2PS)2]ꢀ (R = alkyl or
aryl) (Scheme 1) are versatile ligands that can form sta-
ble complexes with a range of transition and main group
metal ions [8–12].
Nevertheless, organometallic complexes of Ru con-
taining dithioimidophosphinates have not been well
explored [13–18]. Recently, we have demonstrated that
the electron-rich [Ru{N(R2PS)2}2] core can stabilize a
variety of reactive unsaturated species including SO
[16], diazene [17], and carbene [18]. As our continuing
effort to investigate the catalytic chemistry of electron-
rich Ru/S complexes, we set out to prepare unsatu-
rated, half-sandwich Ru dithioimidophosphinate
complexes. Although half-sandwich (g6-arene)Ru(II)
[14,15], Cp*Rh(III) [14,15,19], and Cp*Ir(III) [15,19]
Coordinately unsaturated organometallic compounds
play important roles as reactive intermediates in homoge-
neous catalysis. Of interest are 16-electron, half-sandwich
Ru(II) complexes that were found to be reactive toward
unsaturated organic substrates and small molecules [1].
Coordinately unsaturated Ru(II) cyclopentadienyl (Cp)
complexes are usually associated with bulky electron-
releasing co-ligands, notably phosphines. 16-electron
Ru(II) Cp complexes of the types [CpRu(L)(X)] (L =
phosphine, X = mono-anionic ligand) and [CpRu(LÙL)]+
(L = neutral bidentate ligand such as diphosphine and
diamine) are well documented. The unsaturation of the
CpRu(II) core can also be stabilized by p-donation of col-
igands [1–3]. Recently, [Cp*Ru{PhC(NBut)2}] (Cp* =
g5-C5Me5) that shows a nearly planar geometry with the
*
Corresponding author. Tel.: +852 2358 7360; fax.: +852 2358 1594.
E-mail address: chleung@ust.hk (W.-H. Leung).
0020-1693/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2005.04.031

W.-M. Cheung et al. / Inorganica Chimica Acta 359 (2006) 782–788
783
Upon warming room temperature, the color change
from red to purple was observed. The purple solution
was stirred for 2 h at room temperature. The solvent
was pumped off and the oil was extracted with hexane.
Concentration and cooling at ꢀ10°C gave purple crys-
tals. Yield: 38 mg, 55%. Anal. Calc. for C34H35NP2Ru-
S2 Æ H2O: C, 58.1; H, 5.3; N, 2.0. Found: C, 58.3; H,
5.0; N,2.0%. H NMR (300 MHz, C6D6): d = 8.14 (m,
8H, Ph), 7.08 (m, 12H, Ph), 1.27 (s, 15H, Cp*) ppm.
31P{1H} NMR (121.5 MHz, C6D6): d = 29.33 (s) ppm.
S
P
S
P
R
R
R
R
N
[N(R2PS)2]-
Scheme 1.
1
complexes with [N(R2PS)2]ꢀ have been synthesized,
the isoelectronic Cp*Ru(II) analogue is unknown.
Herein, we describe the synthesis, crystal structure,
and reactivity of the first 16-electron, half-sandwich
Ru(II) complex supported by [N(R2PS)2]ꢀ.
2.4. Synthesis of [Cp*Ru{N(Ph2PS)2}(CO)] (3)
CO gas was bubbled slowly through a solution of 2
(70 mg) in hexane (20 ml) for 1 min, during which time
the color changed from purple to yellow. A yellow pre-
cipitate was formed after the solution was stirred for ca.
1 h. The yellow solid was collected and recrystallized
from CH2Cl2/hexane to give yellowish orange crystals.
Yield: 27 mg, 38%. Anal. Calc. for C35H35NOP2RuS2:
C, 59.0; H, 5.0; N, 2.0. Found: C, 58.9; H, 5.0; N,
2. Experimental
2.1. General
All manipulations were carried out under nitrogen by
standard Schlenk techniques. Solvents were purified,
distilled and degassed prior to use. NMR spectra were
recorded on a Varian Mercury 300 spectrometer operat-
1
2.0%. H NMR (300 MHz, CDCl3): d = 7.95 (m, 8H,
Ph), 7.36 (m, 12H, Ph), 1.51 (s, 15H, Cp*) ppm.
31P{1H} NMR (121.5 MHz, CDCl3): d = 37.18 (s)
ppm. IR (KBr, cmꢀ1): 1929 [m(C„O)].
ing at 300 and 121.5 MHz for H and 31P, respectively.
1
Chemical shifts (d, ppm) were reported with reference
to SiMe4 (1H) and H3PO4 (31P). Infrared spectra
(KBr) were recorded on a Perkin–Elmer 16 PC FT-IR
spectrophotometer. Cyclic voltammetry was performed
with a Princeton Applied Research (PAR) Model
273A potentiostat. The working and reference electrodes
were glassy carbon and Ag/AgNO3 (0.1 M in acetoni-
2.5. Synthesis of [Cp*Ru{N(Ph2PS)2}(L)]
(L = xylNC) where xyl = 2,6-dimethylphenyl (4),
MeO2CC„CCO2Me (5)
To a solution of 2 (70 mg) in hexane (20 ml) was added
1 equivalent of L at 0°C. The resulting mixture was stir-
red at room temperature for 15 min, during which time
the color changed from purple to yellow. The solution
was evaporated to dryness and the residue recrystallized
from THF/Et2O at ꢀ10°C to give orange solids.
trile), respectively, and the scan rate was 100 mV sꢀ1
.
Formal potentials were measured in CH2Cl2 solutions
with 0.1 M ½NBun4ꢁ½PF6ꢁ as supporting electrolyte and re-
ported with reference to the ferrocenium–ferrocene cou-
ple (Cp2Fe+/0). Elemental analyses were performed by
Medac Ltd., Surrey, UK. The ligand K[N(Ph2PS)2]
[20] and [Cp*RuCl2]x [21] were prepared according to
the literature methods.
4: Yield: 29 mg, 35%. Anal. Calc. for C43H46-
N2P2RuS2: C, 63.1; H, 5.7; N, 3.4. Found: C, 63.5; H,
5.7; N, 3.3%. 1H NMR (300 MHz, C6D6): d = 8.25–
8.20 (m, 8H, Ph), 7.05–6.83 (m, 12H, Ph), 6.75–6.74
(m, 3H, xyl), 2.24 (s, 6H, Me), 1.57 (s, 15H, Cp*)
ppm. 31P{1H} NMR (121.5 MHz, C6D6): d = 32.03 (s)
ppm. IR (KBr, cmꢀ1): 2045 [m(C„N)].
2.2. Synthesis of [Cp*Ru{N(Ph2PS)2}Cl] (1)
A mixture of [Cp*RuCl2]x (60 mg, 0.10 mmol) and
K[N(Ph2PS)2] (0.20 mmol) in THF (15 ml) was stirred
at room temperature for 1 h, during which the brown
suspension changed to red solution. The solvent was
pumped off, and the residue was washed with Et2O.
Recrystallization from CH2Cl2/hexane at room temper-
ature afforded red blocks. Yield: 56 mg, 78%. Anal.
Calc. for C34H35ClNP2RuS2: C, 56.7; H, 4.9; N, 2.0.
Found: C, 56.3; H, 4.9; N, 1.8%.
5: Yield: 35 mg, 42%. Anal. Calc. for C40H41NO4-
P2RuS2: C, 58.0; H, 5.0; N, 1.7. Found: C, 57.2; H,
1
5.2; N, 1.9%. H NMR (300 MHz, CDCl3): 7.85–7.58
(m, 8H, Ph), 3.69 (s, 6H, Me), 1.35 (s, 15H, Cp*)
ppm. 31P{1H} NMR (121.5 MHz, CDCl3): d = 34.67
(s) ppm. IR (KBr, cmꢀ1): 1887 [m(C„C)], 1706, 1698,
1688 [m(C@O)].
2.6. Synthesis of [Cp*Ru(S2CNMe2)2][N(Ph2PS)2]
(6)
2.3. Synthesis of [Cp*Ru{N(Ph2PS)2}] (2)
To a solution of 1 (72 mg, 0.10 mmol) in THF (20 ml)
was added Li[BEt3H] (0.1 ml, 1 M in THF) at ꢀ78°C.
To solution of 2 (68 mg, 0.1 mmol) in THF (10 ml)
was added 1 equivalent of tetramethylthiuram disulfide

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W.-M. Cheung et al. / Inorganica Chimica Acta 359 (2006) 782–788
and the mixture was stirred at room temperature over-
night. The solvent was pumped off and the oil was
washed with Et2O. Recrystallization from CH2Cl2/
Et2O afforded reddish brown crystals. Yield: 26%. Anal.
Calc. for C36H52N3P2RuS6 Æ 2H2O: C, 50.0; H, 5.3; N,
4.4. Found: C, 49.5; H, 5.2; N, 4.1%. 1H NMR
(300 MHz, CDCl3): d = 8.16–8.09 (m, 8H, Ph), 7.21–
7.16 (m, 12H, Ph), 3.20 (s, 12H, Me), 1.49 (s, 15H,
Cp*) ppm. 31P{1H} NMR (121.5 MHz, CDCl3):
d = 35.82 (s) ppm.
split into two sites of 0.6 and 0.4 occupancies. Selected
bond lengths and angles for complexes 1, 2 and 6 are
listed in Tables 2 and 3.
3. Results and discussion
3.1. Half-sandwich Ru(III) and Ru(II) complexes with
[N(PR2S)2]ꢀ
The synthesis and reactivity of Cp*Ru complexes
with [N(Ph2PS)2]ꢀ are summarized in Scheme 2.
2.7. X-ray crystallography
Treatment of [Cp*RuCl2]x with K[N(R2PS)2] afforded
the mononuclear Ru(III) complex [Cp*Ru{N(R2PS)}Cl]
(1). Complex 1 is air stable in both the solid state and
solution. Reduction of 1 with Li[BEt3H] in THF afforded
the 16-electron Ru(II) complex [Cp*Ru{N(Ph2PS)2}]
(2). Alternatively, complex 2 could be prepared by reac-
tion of [Cp*RuCl]4 [24] with K[N(Ph2PS)2]. Complex 2 is
highly air sensitive in both the solid state and solution. In
the 1H NMR spectrum of 2, the Cp* protons appears as
a singlet at d 1.27 ppm. The 31P {1H} NMR spectrum
displays a singlet at d 29.33 ppm that is more downfield
than that for K[N(Ph2PS)2] (d 37.2 ppm).
Complexes 1 and 2 have been characterized by X-ray
crystallography; selected bond lengths and angles are
collected in Table 2. Fig. 1 shows a perspective view of
1. The structure of 1 is similar to that of [Cp*Ir-
{N(Ph2PS)2}Cl] [19] showing a boat-like conformation
A summary of crystallographic data and experimental
details for [Cp*Ru{N(Ph2PS)2}Cl] (1), [Cp*Ru{N(Ph2-
PS)2}] (2), and [Cp*Ru(S2CNMe2)2][N(Ph2PS)2] Æ
1/2H2O (6 Æ 1/2H2O) are summarized in Table 1. Intensity
data were collected on a Bruker SMART APEX 1000
CCD diffractometer using graphite-monochromated
˚
Mo Ka radiation (k = 0.71073 A) at 100(2) K. The col-
lected frames were processed with the software SAINT
[22]. Structures were solved by the direct methods and re-
fined by full-matrix least-squares on F2 using the SHELXTL
[23] software package. Non-hydrogen atoms were refined
anisotropically. The Cp* ligand in 6 was found to be dis-
ordered, and the carbon atoms C(1)–C(10) are split into
two sites of 0.7 and 0.3 occupancies. In addition, one of
the phenyl groups in the [N(Ph2PS)2]ꢀ anion is disor-
dered. The disordered carbon atoms C(83)–C(85) are
Table 1
Crystallographic data for [Cp*Ru{N(Ph2PS)2}Cl] (1), [Cp*Ru{N(Ph2PS)2}] (2), and [Cp*Ru(S2CNMe2)2][N(Ph2PS)2] Æ 1/2H2O (6 Æ 1/2H2O)
Compound
1
2
6 Æ 1/2H2O
Empirical formula
Formula weight
Crystal system
C34H35ClNP2RuS2
720.21
monoclinic
C34H35NP2RuS2
684.76
monoclinic
C40H48N3O0.50P2RuS6
934.18
triclinic
Unit cell dimensions
˚
a (A)
˚
17.261(1)
10.485(1)
17.626(1)
8.835(1)
13.032(1)
28.308(2)
14.675(1)
17.575(1)
18.103(1)
71.411(1)
89.411(1)
77.119(1)
4304.7(4)
b (A)
˚
c (A)
a (°)
b (°)
c (°)
99.199(1)
91.049(1)
3
˚
V (A )
3149.0(3)
P21/n
3258.8(4)
P21/c
ꢀ
Space group
Z
P1
4
1.519
4
1.396
4
1.441
Dcalc (g cmꢀ3
Temperature (K)
)
100(2)
1476
0.843
100(2)
1408
0.731
100(2)
1932
0.764
F(000)
l(Mo Ka) (mmꢀ1
Total reflection
Independent reflection
)
17057
6106
16590
5712
22410
14831
Rint
0.0202
0.0263, 0.0638
0.0289, 0.0651
1.054
0.0215
0.0418, 0.1140
0.0487, 0.1178
1.053
0.0266
0.0525, 0.1228
0.0721, 0.1310
1.008
b
R1a, wR2 (I > 2r(I))
R1, wR2 (all data)
Goodness-of-fitc
a
R1 = RiFo| ꢀ |Fci/R|Fo|.
2
2 1=2
b
wR2 ¼ ½RwðjF 2oj ꢀ jF c2jÞ =RwjF 2j ꢁ
.
GoF ¼ ½RwðjF oj ꢀ jF cjÞ =ðNobso ꢀ NparamÞꢁ
.
2
1=2
c

W.-M. Cheung et al. / Inorganica Chimica Acta 359 (2006) 782–788
785
Table 2
Selected bond lengths and angles for [Cp*Ru{N(Ph2PS)2}Cl] (1) and
[Cp*Ru{N(Ph2PS)2}] (2)
1
2
˚
Bond length (A)
Ru(1)–Cp*a
Ru–S(1)
Ru–S(2)
1.827
1.739
2.370(1)
2.388(1)
2.3888(5)
2.3778(5)
2.3990(5)
2.0261(7)
2.0270(7)
1.582(2)
1.580(2)
Ru–Cl(1)
P(1)–S(1)
P(2)–S(2)
P(1)–N(1)
P(2)–N(1)
2.020(1)
2.007(1)
1.588(3)
1.593(3)
Bond angle (°)
S(1)–Ru(1)–S(2)
S(1)–Ru(1)–Cl(1)
S(2)–Ru(1)–Cl(1)
P(1)–N(1)–P(2)
ab
97.28(2)
93.18(2)
92.87(2)
103.46(3)
136.7(1)
126.0(2)
177.4
a
Ru–Cp* (centroid) distance.
b
Pyramidalization angle is the angle between the centroid of the Cp*
ring, Ru, and the centroid of the S–Ru–S moiety [1].
Fig. 1. Molecular structure of [Cp*Ru{N(Ph2PS)2}Cl] (1).
for the (Ru–S–P–N–P0–S0) ring (Fig. 2). The Ru–
˚
Cp*(centroid) distance is 1.827 A. The Ru–Cl distance
˚
of 2.3990(5) A is comparable to those in Cp*Ru(III)
˚
complexes (e.g., 2.366 A for [Cp*RuCl2]2 [25]). The
˚
average Ru–S distance of 2.3833(5) A is slightly shorter
˚
than that in [Ru{N(Ph2PS)2}3] (2.414 A) [16]. Similar to
other dithioimidophosphinate complexes, the average
˚
P–S distance (2.0266(7) A) in 1 is longer than that
˚
for HN(Ph2PS)2 (average 1.944 A) whereas the average
˚
P–N distance (1.581(2) A) is shorter than that of the
˚
latter (1.678 A).
Fig. 2. A view of the Ru–S–P–N–P0–S0 ring in 1 showing the boat-like
conformation.
K[N(Ph2PS)2]
Li[BEt3H]
[Cp*RuCl2]x
Ru
Ru
Ph
S
Cl
S
P
S
P
Ph
P
Ph
Ph
Ph
Ph
S
N
P
Ph
N
Ph
2
1
L
(Me2NCS2)2
[N(PPh2S)2]
Ru
S
Ph
S
L
Ru
Ph
P
S
S
S
S
N
Me2NC
CNMe2
P
Ph
6
Ph
L = CO (3)
= xylNC (4)
=
(
5)
MeO2C
C
C
CO2Me
Scheme 2.

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W.-M. Cheung et al. / Inorganica Chimica Acta 359 (2006) 782–788
Fig. 3. Molecular structure of [Cp*Ru{N(Ph2PS)2}] (2).
Fig. 4. Side view of 2.
The molecular structure of 2 is shown in Fig. 3.
Although 16-electron half-sandwich [CpRu(LL)]n (L =
N- or P-donor ligand, n = + or 0) as well as [(g6-are-
ne)Ru(SR)2] [26] have been isolated, to our knowledge,
2 is the first unsaturated Cp*Ru(II) complex supported
a bidentate sulfur ligand. Complex 2 exhibits a 2-legged
piano-stool structure with an approximate perpendicu-
lar arrangement between the Cp* ring and the plane de-
fined by the Ru and two sulfur atoms (Fig. 4). The
pyramidization angle (a), which is defined as the angle
of Cp*(centroid)–Ru–RuS2 centroid [1], for 2 is 177.4°,
indicative of the r and p donation by the sulfur ligand
that mitigates the coordinative unsaturation of the com-
plex [1,3]. A similar structure has been found for the iso-
electronic Ir(III) analogue [Cp*Ir{N(Ph2S)2}]+ [19]. The
indicating that [N(Ph2PS)2]ꢀ is a weaker donor than
the amidinate. The 31P {1H} NMR spectrum of 3 dis-
plays a singlet at d 37.18 ppm that is more downfield
that that for 2. Similarly, treatment of 2 with 2,6-dim-
ethylphenyl isocyanide (xylNC) afforded air-stable
[Cp*Ru{N(Ph2-PS)2}(xylNC)] (4) that exhibits IR
m(CN) at 2045 cmꢀ1. Similar to 3, the 31P NMR reso-
nance for 4 (d = 32.03 ppm) is more downfield than that
of 2. Treatment of 2 with dimethyl maleate afforded the
alkyne complex [Cp*Ru{N(Ph2PS)2}(MeCO2C„C-
CO2Me)] (5) that exhibits a resonance at d 38 ppm in
the 31P NMR spectrum. The IR spectrum of 5 shows
m(C„C) at 1887 cmꢀ1, indicative of Ru-to-alkyne
backbonding.
˚
Ru–Cp*(centroid) distance of 1.739 A in 2 is apparently
shorter than that in 1. The average Ru–S distance of
˚
2.379(1) A is similar to that 1 but is slightly shorter than
˚
that in [Ru{N(Ph2PS)2}2(PPh3)] (average 2.400 A) [16].
3.3. Electrochemistry
The S–Ru–S angle in 2 (103.46(3)°) is larger than 1
(97.28(2)°) whereas the P–N–P angle in the former
(126.0(2)°) is smaller than that in the latter (136.7(1)°).
Formal potentials of the Ru complexes have been
determined by cyclic voltammetry. The cyclic voltam-
mogram of 1 at a glassy carbon electrode in CH2Cl2
exhibits reversible couples at 0.08 and ꢀ0.48 V vs.
Cp2Fe+/0, which are tentatively assigned as the Ru(IV/
III) and Ru(III/II) couples, respectively. However, we
do not rule out the ligand contributions in these couples
given the non-innocent nature of sulfur ligands. Despite
the low observed oxidation potential of 1, attempts to
synthesize the Ru(IV) species by oxidation of 1 with
Ag(CF3SO3) or I2 were unsuccessful. The Ru(III/II)
couples for 3 and 4 were observed at considerably higher
potentials (0.79 and 0.53 V, respectively) due to the
p-acceptor property of carbonyl and isocyanide. The
oxidation of the alkyne complex 5 at ca. 0.24 V is irre-
versible. The observed Ru(III/II) redox potentials for
3.2. Adduct formation of 2
Complex 2 reacted readily with 2-electron ligands to
give 18-electron adducts, as evidenced by the 31P {1H}
NMR spectroscopy. The N-donor adducts [Cp*Ru-
{N(Ph2PS)2}(L)] (L = N-donor ligand, e.g., MeCN)
were found to be air sensitive. More stable adducts were
obtained with strong p acid ligands such as CO and iso-
cyanides. Thus, treatment of 2 with CO afforded air-sta-
ble [Cp*Ru{N(Ph2PS)2}(CO)] (3). The IR spectrum of 3
shows the CO band at 1929 cmꢀ1, which is higher
than that in [Cp*Ru{PhC(NBut)2}] (1888 cmꢀ1) [4],

W.-M. Cheung et al. / Inorganica Chimica Acta 359 (2006) 782–788
787
3.4. Oxidation of 2
Complex 2 is readily air oxidized in solutions to give
an uncharacterized dark red species. Oxidation of 2 with
Ag(CF3SO3) afforded a brown solid that has not been
characterized. No oxidative addition was found when
2 was reacted with H2, MeI, or silanes. Complex 2 was
also oxidized by disulfides. Treatment of with 4-tolyl
disulfide afforded a paramagnetic red species, possibly
a Ru(III) species, which has not yet been obtained in
pure form. Interestingly, treatment of 2 with tetrameth-
ylthiuram disulfide gave a diamagnetic compound char-
acterized as [Cp*Ru(S2CNMe2)2][N(Ph2PS)2] (6). The
31P {1H} NMR spectrum of 6 displays a singlet at d
35.82 ppm due to the [N(Ph2PS)2]ꢀ anion. It seems likely
that the formation of 6 involves the oxidation of 2 by
tetramethylthiuram disulfide and subsequent substitu-
tion of [Me2NCS2]ꢀ for the [N(Ph2PS)2]ꢀ ligand.
The solid-state structure of 6 has been established
by X-ray crystallography. Crystals of 6 Æ 1/2H2O con-
tains two independent molecules in the asymmetric
unit. The structure of one of the two crystallographi-
cally independent molecules is shown in Fig. 5; se-
lected bond lengths and angles are listed in Table 3.
Complex 6 exhibits a 4-legged piano-stool structure
typical for Ru(IV) mono cyclopentadienyl complexes.
It should be noted that non-hydrido Ru(IV) cyclopen-
tadienyl complexes are rather rare.ꢂ Previously, the
Cp*Ru(IV) selenoate complex ½Cp Ruðg2-Se2PPr2i Þ-
ðg2-SePPr2i Þꢁ½PF6ꢁ has been synthesized from [Cp*Ru-
Fig. 5. Molecular structure of [Cp*Ru(S2CNMe2)2][N(Ph2PS)2] (6).
Table 3
Selected bond lengths and angles for [Cp*Ru(S2CNMe2)][N(PSPh2)2]
(6).
˚
Bond length (A)
Ru–Cp*a
1.897
Ru(1)–S(1)
Ru(1)–S(2)
Ru(1)–S(3)
Ru(1)–S(4)
Ru(2)–S(5)
Ru(2)–S(6)
Ru(2)–S(7)
Ru(2)–S(8)
2.391(1)
2.388(1)
2.387(1)
2.378(1)
2.393(1)
2.383(1)
2.378(1)
2.396(1)
(MeCN)3][PF6]
and
K½NðPri2PSeÞ ꢁ
[27].
The
2
˚
Ru–Cp*(centroid) distance of 1.897 A isþ similar to
ꢂ
i
i
that in ½Cp Ruðg2-Se2PPr2Þ ðg2-SePPr2Þꢁ (1.916 A)
[27]. It should be noted that the Ru–Cp*(centroid)
distances in the Cp*Ru complexes described in this
work were found to decrease in the order Ru(IV)
(6) > Ru(III) (1) > Ru(II) (2), as the formal coordina-
tion number of the complexes decreases from 7 to 5.
˚
Bond angle (°)
S(1)–Ru(1)–S(2)
S(1)–Ru(1)–S(4)
S(1)–Ru(1)–S(3)
S(3)–Ru(1)–S(4)
S(2)–Ru(1)–S(3)
S(2)–Ru(1)–S(4)
S(7)–Ru(2)–S(5)
S(6)–Ru(2)–S(5)
S(7)–Ru(2)–S(8)
S(6)–Ru(2)–S(8)
S(5)–Ru(2)–S(8)
S(7)–Ru(2)–S(6)
71.07(4)
124.45(4)
84.71(4)
71.54(4)
126.24(5)
83.71(4)
128.52(5)
70.76(4)
71.14(5)
121.67(5)
86.17(5)
82.77(5)
˚
The average Ru–S distance (2.387(1) A) for 6 is short-
˚
er than that in [Ru(S2CNMe2)3Cl] (Ru–Seq 2.416 A)
[28].
4. Conclusions
In summary, we have synthesized and structurally
characterized the first 16-electron Cp*Ru(II) dith-
ioimidophosphinate complex, which exhibits an approx-
imately perpendicular arrangement between the Cp* ring
and the Ru–S–S0 plane. [Cp*Ru{N(Ph2PS)2}] reacted
with 2-electron ligands including CO, 2,6-Me2C6H4NC,
and dimethyl maleate to give the corresponding 18-elec-
tron adducts. Oxidation of [Cp*Ru{N(Ph2PS)2}] with
a
Average Ru–Cp*(centroid) distance.
[Cp*Ru{N(Ph2PS)2}L] is consistent with the order of p
acidity CO > xylNC > MeCO2C„CCO2Me. For 3, a
reversible reduction couple at ꢀ0.04 V was also ob-
served. This reduction couple is possibly ligand-centered
because the reduction of Ru(II) is expected to occur at a
more negative potential.
tetramethylthiuram disulfide afforded
a
novel
Cp*Ru(IV) dithiocarbamate complex [Cp*Ru(S2CN-
Me2)2][N(Ph2PS)2]. The study of the reactivity of Cp*Ru

788
W.-M. Cheung et al. / Inorganica Chimica Acta 359 (2006) 782–788
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dithioimidodiphosphinate complexes toward unsatu-
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5. Supplementary material
[9] J.D. Woollins, J. Chem. Soc., Dalton Trans. (1996) 2893.
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Crystallographic data for [Cp*Ru{N(Ph2PS)2}Cl]
(1), [Cp*Ru{N(Ph2PS)2}] (2), and [Cp*Ru(S2CNMe2)2]-
[N(Ph2PS)2] Æ 1/2H2O (6 Æ 1/2H2O) have been deposited
with the Cambridge Crystallographic Data Centre as
Supplementary Publication Nos. CCDC 263955–
263957, respectively. Copies of the data can be obtained
free of charge on application to CCDC, 12 Union Road,
Cambridge CB2 1EZ, UK, fax: +44 1223 336 033,
e-mail: deposit@ccdc.cam.ac.uk.
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This work was supported by the Hong Kong Univer-
sity of Science and Technology and the Hong Kong Re-
search Grants Council. We thank Dr. Herman Sung for
solving the crystal structures.
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