Reactivity of the [CpM(PPh3)2]+ (M = Ru, Os) fragment with diethyldithiocarbamate

Article abstract of DOI:10.1016/j.poly.2006.09.042

This paper reports on the reaction of [CpM(PPh₃)₂(L)]^+/0(Cp = η⁵-C₅H₅; M = Os, L = CH₃CN, DMSO Br; M = Ru, X = Cl, CH₃CN) with diethyldithiocarbamate (S₂ CN

Full text of DOI:10.1016/j.poly.2006.09.042

Polyhedron 26 (2007) 867–870
www.elsevier.com/locate/poly
Reactivity of the [CpM(PPh3)2]+ (M = Ru, Os) fragment with
diethyldithiocarbamate
a,
b
c
a
R. Lalrempuia *, Hauzachin Suante , Hemant P. Yennawar , Mohan Rao Kollipara
a
Department of Chemistry, School of Physical Sciences, North Eastern Hill University, Shillong 793022, Meghalaya, India
b
Indian Institute of Technology Kanpur, Kanpur 208016, UP, India
Department of Biochemistry and Molecular Biology, The Pennsylvania State University, PA 16802, USA
c
Received 11 July 2006; accepted 15 September 2006
Available online 29 September 2006
Abstract
This paper reports on the reaction of [CpM(PPh3)2(L)]+/0(Cp = g5–C5H5; M = Os, L = CH3CN, DMSO Br; M = Ru, X = Cl,
CH3CN) with diethyldithiocarbamate (S2CNEt2ꢀ). The exceptional kinetic stability of [Os–PPh3] compared to [Ru–PPh3] is reflected
from the isolation of the monodentate diethyldithiocarbamate complex [CpOs(PPh3)2(j1-S2CNEt2)] (3) and the bidentate diethyldithio-
carbamate complex [CpRu(PPh3)(j2-S2CNEt2)] (5) as the only products. The structure of [CpOs(PPh3)2(CH3CN)]BF4 (2 Æ BF4) and 5
were determined by X-ray diffraction.
ꢀ 2006 Elsevier Ltd. All rights reserved.
Keywords: Osmium; Ruthenium; Dithiocarbamates; Cyclopentadienyl; X-ray diffraction
1. Introduction
and have demonstrated that this compound is a much more
desirable precursor for the preparation of chelate com-
plexes of the type [CpOs(PPh3)(LL0)]BF4(LL0 = bipy,
phen) [6]. In pursuance of our interest in the synthesis of
new complexes essentially bearing a cyclopentadienyl
ligand, we wish to report here the contrasting reactivity
behavior of the [CpM(PPh3)2]+ (M = Os, Ru) fragment
towards diethyldithiocarbamate.
Dithiocarbamates are versatile ligands, capable of form-
ing complexes with all the transition elements and able to
stabilize most in a range of oxidation states [1]. The CS2
ꢀ
group in dithiocarbamates (dtc) is usually a chelate but a
few cases of monodentate dithiocarbamates are known
[2]. Recently, Baird et al. have reported the unique chemis-
try of amino acid dithiocarbamates with the Ru(III) system
where a very interesting CS2ꢀ elimination phenomenon was
observed [3]. As far as the [CpM(PPh3)2X] (M = Ru,
X = Cl; M = Os, X = Br) systems are concerned, these
compounds serve as excellent precursors for various orga-
nometallic complexes [4] and show very similar reactivity
patterns except that the [Os]–PPh3 bond is kinetically much
more stable. Some dithiocarbamate as well as xanthate
complexes have been known in both cases [5]. We have
reported earlier, the preparation and reactivity of the ace-
tonitrile complex [CpOs(PPh3)2(CH3CN)]BF4 (2 Æ BF4)
2. Results and discussion
The reaction of [CpOs(PPh3)2Br] with the sodium salt of
diethyldithiocarbamate, Na Æ S2CNEt2 in acetonitrile sol-
vent in the presence of NH4BF4 under refluxing conditions
lead to the formation of the monodentate [S2CNEt2] com-
plex [CpOs(PPh3)2(j1-S2CNEt2)] (3) and a cationic com-
plex, [CpOs(PPh3)2(CH3CN)]BF4 (2 Æ BF4). Our earlier
attempts to isolate pure 3 from [CpOs(PPh3)2Br] and
Na Æ S2CNEt2 using methanol as a solvent were unsuccess-
1
ful. The H NMR spectrum showed the presence of a 1:1
*
ratio of complexes 3 and 2 Æ BF4 in the crude product, apart
from the resonances corresponding to 2 Æ BF4, the
Corresponding author. Tel.: +91 389 2335159.
E-mail address: lrpa@rediffmail.com (R. Lalrempuia).
0277-5387/$ - see front matter ꢀ 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.09.042

868
R. Lalrempuia et al. / Polyhedron 26 (2007) 867–870
resonances of the methylene protons of the [S2CNEt2]
ligand of complex 3 appear as two sets of quartets at
4.03 and 3.72 ppm. A triplet at 1.27 ppm, assignable to
the methyl protons of the [S2CNEt2] ligand, was also
observed. Protons corresponding to the cyclopentadienyl
ligand also appear at 4.74 ppm while the PPh3 peaks are
observed as a bunch in the aromatic region. The IR spec-
trum taken in KBr showed a strong peak at 1491 cmꢀ1
,
unambiguously assignable to the mCN vibration of
[S2CNEt2] [7]. We also observed bands at 2277 cmꢀ1 and
1084 cmꢀ1 assignable to mCN of coordinated CH3CN and
mBF of BF4ꢀ. We have employed this synthetic strategy
hoping that the in situ generated complex [CpOs(PPh3)2-
(CH3CN)]BF4 (2 Æ BF4) would easily give 3 or the chelate
complex [CpOs(PPh3)2(j2-S2CNEt2)]. Unfortunately, we
never obtain the latter compound, and to our surprise
attempts to separate 2 Æ BF4 and 3 proved to be futile owing
to the similar solubility of these two complexes.
Fig.ꢀ1. Molecular structure of [CpOs(PPh3)2(MeCN)]BF4 (2 Æ BF4) with
BF4 and all the hydrogens atoms omitted for clarity.
1
Then, we attempted to synthesize 3 from [CpOs(PPh3)2-
(CH3CN)]BF4 (2 Æ BF4) and Na Æ S2CNEt2 in refluxing
methanol (Scheme 1). The formation of 3 may be gauged
by the appearance of white precipitate after about one hour
of refluxing. But to our surprise, a 1H NMR spectrum
taken in CDCl3 of this crude product still showed the pres-
ence of 2 Æ BF4. Fortunately, after many attempts, we were
able to get single crystals from this crude product by slow
diffusion of hexane into an acetone solution of this mixture;
very pale yellow crystals were obtained after one week leav-
ing an oily blackish-yellow residue on the wall of the crys-
The H NMR spectrum showed a resonance of the methyl
group of the coordinated DMSO at 3.53 and 3.43 ppm.
The 13P{1H} NMR showed a singlet at ꢀ2.67 ppm, sug-
gesting a similar environment of both P atoms of the
PPh3 ligands. Thus, all our attempts to isolate the pure
[CpOs(PPh3)2(j1-S2CNEt2)] (3) were unsuccessful.
In the complex [CpOs(PPh3)2(CH3CN)]BF4 (2 Æ BF4), the
osmium(II) centre adopts a pseudo-octahedral coordina-
tion geometry with an almost linear Os1–N1–C1 (171.16ꢁ)
moiety occupying one site. The bond lengths N1–C1
˚
˚
(1.132(6) A) and C1–C43 (1.455(8) A) are in very close
agreement with those reported for [CpRu(CH3CN)3]BF4
1
tallization tube and the H NMR spectrum revealed that
I
this is a decomposed material. The H NMR, 13P{1H}
˚
˚
where N–Cav = 1.131 A and C–Cav = 1.445 A [9]. The
other coordination sites are occupied by a pentahapto-
bound cyclopentadienyl ligand and two triphenylphos-
phines. The Os–P1 and Os–P2 bond lengths [2.328 A and
2.343 A respectively] are comparable with those found in
NMR, IR, elemental analysis as well as the X-ray crystal-
lographic analysis of these crystals has revealed that this
compound is the starting [CpOs(PPh3)2(CH3CN)]BF4
(2 Æ BF4). However, as no report of the structural data of
this compound is available in the literature, we have
reported this structure here. The ORTEP diagram is shown
in Fig. 1. For the final attempt, we tried the reaction start-
ing from a new complex [CpOs(PPh3)2(DMSO)]BF4
(4 Æ BF4), however this compound does not seem to
undergo the anticipated substitution reaction in the present
experimental conditions. The complex [CpOs(PPh3)2-
(DMSO)]BF4 (4 Æ BF4) was prepared by the reaction of
[CpOs(PPh3)2Br] with an excess of DMSO in methanol.
The compound is isolated as a very pale yellow hydro-
scopic powder. It was characterized with the help of IR,
1H and 13P{1H} spectroscopy. The IR spectrum showed
a band at 1023 cmꢀ1, assignable to S-bound DMSO [8].
˚
˚
[CpOs(@C@C@CPh2)(PPh3)2][PF6] [10] and [CpOs(PPh3)2-
(OSO2CF3)] [11].
We have extended our work to a closely related system,
the reaction of [CpRu(PPh3)2Cl] or [CpRu(PPh3)2(CH3-
CN)]BF4 with Na.S2CNEt2 leads to the formation of an
orange colored complex that is soluble in almost all com-
mon solvents, even in hexane. The IR spectrum showed a
strong mCN peak at 1483 cmꢀ1. The 1H NMR spectrum
showed the resonance of the cyclopentadienyl ligand at
6.22 ppm, a bunch of peaks corresponding to methylene
proton in the range of 3.76–4.42 ppm and a triplet at
1
1.28 ppm. Thus, IR and H NMR data clearly suggested
the formation of the expected well-known bidentate
Na[S CNEt ]
+
2
2
Os
PPh3
Os
S2CNEt2
+
NCCH
3
Br
Os
MeCN
Ph3P
Ph3P
Ph P
3
PPh3
PPh
3
3
2
Scheme 1.

R. Lalrempuia et al. / Polyhedron 26 (2007) 867–870
869
0.055 mmol) in 10 mL methanol was refluxed for 10 h,
whereby the color of the solution changed to bright yellow
with some whitish materials settling down at the bottom of
the flask. The solvent was removed in vacuo and the residue
was extracted with CH2Cl2 and filtered through a short sil-
ica gel column. Subsequent concentration and addition of
excess hexane yielded a pale yellow powder containing a
mixture of 3 and 2 Æ BF4. Yield: 0.038 g. 1H NMR (CDCl3,
d): 7.67–7.20 (m, 30H, Ph), 4.74 (s, 5H, Cp), 4.03 (qr, 2H,
7 Hz, CH2), 3.72 (qr, 2H, 7 Hz, CH2), 1.27 (t, 6H, CH3).
13P {1H NMR}: ꢀ1.53 (s). IR (KBr, cmꢀ1): 1491 (w),
1433 (ms), 1084 (mBF, s), 1055 (s), 750 (m), 697 (s).
3.2. Synthesis of [CpOs(PPh3)2(DMSO)]BF4 (4 Æ BF4)
A mixture of [CpOs(PPh3)2Br] (0.1 g, 0.117 mmol) and
dimethylsulfoxide (1 mL, 0.055 mmol) in methanol
(30 mL) was refluxed for 3 h, whereby the color of the solu-
tion changed to very pale transparent yellow. The solvent
was removed in vacuo and the residue was extracted with
CH2Cl2 and loaded onto a short alumina column. The
compound was eluted with methanol. Concentration of
this methanol solution and addition of diethylether with
vigorous shaking gave the very pale yellow solid of
4 Æ BF4. 1H NMR (CDCl3, d): 7.49–7.14 (m, 30H, Ph),
5.47 (s, 5H, Cp), 3.53 (s, 3H, CH3), 3.43 (s, 3H, CH3).
13P {1H NMR}: ꢀ2.67 (s). IR (KBr, cmꢀ1):1023 (mSO),
1089 (mBF).
Fig. 2. Molecular structure of [CpRu(PPh3)2(j2-S2CNEt2)] (5) with all the
hydrogen omitted for clarity.
3.3. Synthesis of [CpRu(PPh3)2(j2-S2CNEt2)] (5)
diethylthiocarbamato complex [CpRu(PPh3)(j2-S2CNEt2)]
(5), the X-ray crystal structure determination also con-
firmed these spectroscopic evidences and has revealed that
the compound contain two independent, discrete molecules
(Fig. 2). The molecules are structurally identical except in
the orientation of the ethyl group of the [S2CNEt2] ligand.
The metrical bonding parameters are comparable to those
found in the analogous complexes [CpRu(PPh3)-
(S2CNMe2)] [12] and [CpRu(PPh3)(S2CNPr2)] [13].
A
mixture of [CpRu(PPh3)2(MeCN)]BF4 (0.05 g,
0.061 mmol) or [CpRu(PPh3)2Cl] (0.044 g, 0.061 mmol)
and Na Æ S2CNEt2 Æ 3H2O (0.014 g, 0.061 mmol) in metha-
nol (10 mL) was refluxed for 8 h, then the solvent was
removed in vacuo and the residue was extracted with
CH2Cl2 and filtered through a short silica gel column.
CH2Cl2 was removed in vacuo and the residue was
extracted with hexane, which on standing overnight yielded
orange crystals of 5. Yield: 0.040 g, 59%. 1H NMR (CDCl3,
d): 7.67–7.31 (m, 30H, Ph), 6.22 (s, 5H, Cp), 4.53–3.42 (m,
12H, CH2), 1.24 (t, 3H, 7.3 Hz, CH3).13P {1H NMR}: 19.6
(s). IR (KBr, cmꢀ1): 1483 (mCN, s), 1457 (w), 1429(s), 1271
(s), 1214(w), 1141(m), 1089 (s), 748 (m), 696(s).
3. Experimental
All solvents were dried and purified by standard proce-
1
dures. H and 13P{1H} NMR spectra were recorded on a
Bruker 300 MHz spectrometer using Me4Si and H2PO4
(85%) respectively as internal standards. IR spectra were
recorded using a Nicolet Impact Spectrophotometer.
Na Æ S2CNEt2 Æ 3H2O was obtained from a commercial
source and was used as received. [CpOs(PPh3)2Br] [14],
[CpOs(PPh3)2(MeCN)]BF4 (2 Æ BF4) [6], [CpRu(PPh3)2X],
(X = Cl, MeCN) [15] were prepared according to literature
procedures.
4. X-ray data collection and solution
Suitable single crystals for X-ray analysis of complex
2 Æ BF4 were grown by slow diffusion of hexane into a con-
centrated acetone solution and 5 were grown by slow evap-
oration of a hexane/dichloromethane solution (1:2 v/v). A
summary of the single-crystal X-ray structure analyses are
shown in Table 1, and selected bond lengths and bond
angles are presented in Tables 2 and 3 respectively. The
X-ray intensity data were measured on a Bruker SMART
APEX CCD area detector system equipped with a graphite
monochromator and a Mo Ka fine-focus sealed tube
3.1. Synthesis of [CpOs(PPh3)2(j1-S2CNEt2)] (3)
A
mixture of [CpOs(PPh3)2(MeCN)]BF4 (2 Æ BF4)
(0.05 g, 0.055 mmol) and Na Æ S2CNEt2 Æ 3H2O (0.013 g,

870
R. Lalrempuia et al. / Polyhedron 26 (2007) 867–870
˚
Table 1
(k = 0.71073 A) operated at 1600 W power (50 kV,
32 mA). The detector was placed at a distance of 5.8 cm
from the crystal. A total of 1850 frames were collected with
a scan width of 0.3ꢁ in x and the frames were integrated
with the Bruker SAINT software package using a narrow-
frame integration algorithm. Data were corrected for
absorption effects using the multiscan technique (SADABS)
[16]. The structures were solved and refined using the
Bruker SHELXTL (Version 6.1) software package [17].
Crystal data summary and structure refinement for complexes 2 Æ BF4
and 5
Empirical formula
Formula weight
Temperature (K)
C43H38BF4NOsP2 C56H60N2P2Ru2S4
907.69
298(2)
1153.38
298(2)
˚
Wavelength (A)
0.71073
monoclinic
P2(1)/c
0.71069
monoclinic
P2(1)/c
Crystal system
Space group
Unit cell dimensions
˚
a (A)
10.2948(13)
17.080(2)
21.840(3)
90.310(2)
3840.1(9)
4
27.226(5)
10.4000(18)
19.566(3)
101.174(3)
5435.0(16)
4
˚
b (A)
Acknowledgements
˚
c (A)
b (ꢁ)
Volume (A )
3
˚
R.L. thanks the Council of Scientific and Industrial Re-
search, India for SRF fellowship and H.P.Y. thanks NSF
grant CHE-0131112 for the X-ray facility.
Z,
Dcalc (Mg/m3)
1.565
1.410
F(000)
1788
3.455
0.45 · 0.20 · 0.10
2368
0.806
Absorption coefficient (mmꢀ1
Crystal size (mm)
)
Appendix A. Supplementary material
0.13 · 0.20 · 0.44
0.76–28.41
ꢀ29 6 h 6 36,
ꢀ13 6 k 6 13,
ꢀ26 6 l 6 17
33187
h Range for data collection (ꢁ) 1.51–28.29
Limiting indices
ꢀ13 6 h 6 10,
CCDC numbers 281619 and 604139 contain the supple-
mentary crystallographic data for 2 Æ BF4 and 5. These data
can be obtained free of charge via http://www.ccdc.cam.a-
c.uk/conts/retrieving.html, or from the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2
1EZ, UK; fax: (+44) 1223-336-033; or e-mail: depos-
it@ccdc.cam.ac.uk. Supplementary data associated with
this article can be found, in the online version, at
doi:10.1016/j.poly.2006.09.042.
ꢀ22 6 k 6 17,
ꢀ29 6 l 6 28
25027
Reflections collected
Independent reflections (Rint
Refinement method
)
9272(0.0364)
full-matrix least-
squares on F2
9272/0/469
1.050
12842(0.0737)
full-matrix least-
squares on F2
7619/0/406
1.014
Data/restraints/parameters
Goodness-of-fit on F2
Final R1
0.0370
0.0813
Final wR2
0.0837
0.1905
Largest difference in peak and
0.886 and ꢀ0.644 0.99 and ꢀ0.815
ꢀ
3
˚
hole (e /A )
References
[1] G. Hogarth, Prog. Inorg. Chem. 53 (2005) 71.
[2] J.V. Dubrawski, R.D. Feltham, Inorg. Chem. 19 (1980) 355.
[3] I.R. Baird, B.R. Cameron, R.T. Skerlj, Inorg. Chim. Acta 353 (2003)
107.
Table 2
Selected bond lengths and angles for the compound [CpOs-
(PPh3)2(CH3CN)]BF4 (2 Æ BF4)
˚
[4] (a) M.A. Bennett, K. Khan, E. Wenger, in: G. Wilkinson, F.G.A.
Stone, E.W. Abel (Eds.), Comprehensive Organometallic Chemistry
II, second ed., vol. 7, Elsevier, Oxford, 1995, p. 513 (Chapter 8);
(b) S.G. Davies, J.P. McNally, A.J. Smallridge, Adv. Organomet.
Chem. 30 (1991) 1.
[5] T. Wilczewski, J. Organomet. Chem. 224 (1982) C1.
[6] R. Lalrempuia, P.J. Carroll, M.R. Kollipara, Polyhedron 22 (2003)
1391.
Bond lengths (A)
Bond angle (ꢁ)
C1–N1
C1–C43
Os1–N1
Os1–P1
Os1–P2
1.132(6)
1.455(8)
2.026(3)
2.328(10)
2.348(10)
Os1–N1–C1
N1–C1–C43
N1–Os1–P1
N1–Os1–P2
P1–Os1–P2
171.1(4)
179.4(9)
98.76(10)
91.76(11)
100.87(3)
[7] (a) F.A. Cotton, J.A. McCleverty, Inorg. Chem. 3 (1964) 1398;
(b) C. O’Connor, J.D. Gilbert, G. Wilkinson, J. Chem. Soc. A. 84
(1969).
[8] (a) A.M. Khenkin, L.J.W. Shimon, R. Neumann, Inorg. Chem. 42
(2003) 3331;
Table 3
Selected bond lengths and angles for the compound [CpRu(PPh3)2-
(j2- S2CNEt2)] (5)
˚
Bond lengths (A)
Bond angle (ꢁ)
(b) N.V. Mockus, J.L. Petersen, J.J. Rack, Inorg. Chem. 45 (2006) 8.
C1–N1
C1–S1
C1–S2
1.344(8)
1.702(7)
1.717(7)
2.4007(18)
2.4133(18)
2.2818(19)
1.320(9)
1.699(7)
1.718(7)
N1–C1–S1
N1–C1–S2
S1–C1–S2
125.2(5)
123.7(5)
110.9(4)
71.61(6)
90.11(6)
94.88(6)
89.1(2)
72.07(7)
88.6(2)
87.9(2)
[9] W. Luginbuhl, P. Zbinden, P.A. Pittet, T. Armbruster, H. Beat Burgi,
¨
¨
A.E. Merbach, A. Ludi, Inorg. Chem. 30 (1991) 2350.
[10] R. Lalrempuia, H. Yennawar, Y.A. Mozharivskyj, M.R. Kollipara, J.
Organomet. Chem. 689 (2004) 539.
Ru1–S1
Ru1–S2
P1–Ru1
C29–N2
C29–S4
C29–S3
Ru2–S3
Ru2–S4
P2–Ru2
S1–Ru1–S2
P1–Ru1–S2
P1–Ru1–S1
C1–S1–Ru1
S4–Ru2–S3
C29–S4–Ru2
C29–S3–Ru2
P2–Ru2–S4
N2–C29–S4
S4–C29–S3
N2–C29–S3
[11] P.W. Wanandi, T. Don Tilley, Organometallics 16 (1997) 4299.
[12] G. Hogarth, S. Faulkner, Inorg. Chim. Acta 359 (2006) 1018.
[13] W. Cordes, M. Draganjac, Acta Crystallogr., Sect. C. 44 (1988) 363.
[14] M.I. Bruce, P.J. Low, B.W. Skelton, E.R.T. Tiekink, A. Werth, A.H.
White, Aust. J. Chem. 48 (1995) 1887.
[15] M.I. Bruce, N.J. Windsor, Aust. J. Chem. 30 (1977) 1601.
[16] Bruker Analytical X-ray Systems, Madison, USA, 2002.
[17] G. Sheldrick, SHELXL-93, Program for Crystal Structure Refinement,
2.3982(19)
2.3921(19)
2.2892(19)
95.44(7)
125.5(6)
111.1(4)
123.4(6)
Institut fur Anorganische Chemie der Universita¨t, Go¨ttingen, Ger-
¨
¨
many, 1993.