Thiosemicarbazonates of ruthenium(II): Crystal structures of [bis(diphenylphosphino)butane][bis(pyridine-2-carbaldehydethiosemicarbazonato)] ruthenium(II) and [bis(triphenylphosphine)][bis(benzaldehydethiosemicarbazonato)] ruthenium(II)

Article abstract of DOI:10.1016/j.poly.2006.04.018

The reaction of Ru₂Cl₄(dppb)₃ {dppb = Ph₂P-(CH₂)₄-PPh₂} with pyridine-2-carbaldehyde thiosemicarbazone {C₅H₄N{single bond}C(H){double bond, long}N³{single bond}N²H{single bond}C({double bond, long}S)NH₂, Hpytsc}, and that of RuCl₂(PPh₃)₃ with benzaldehyde thiosemicarbazone {C₆H₅{single bond}C(H){double bond, long}N³{single bond}N²H{single bond}C({double bond, long}S){single bond}NH₂, Hbtsc}, in the presence of Et₃N base led to loss of the -N²H- proton in each case, and yielded [Ru(pytsc)₂(dppb)] (1) and [Ru(btsc)₂(Ph₃P)₂] (2), respectively. The complexes are characterized with the help of analytical data, IR, NMR (¹H, ¹³C, ³¹P) and single crystal X-ray study. In both compounds 1 and 2, the thiosemicarbazone ligands coordinate to Ru(II) via the hydrazinic nitrogen (N²) and sulfur atoms forming four membered rings, and the pyridyl group is pendant in 1. The geometry is distorted octahedral with cis:cis:trans P, P:N, N:S, S dispositions of donor atoms. Proton NMR confirmed loss of the -N²H- proton in both compounds, and the ³¹P NMR spectra reveal the presence of equivalent phosphorus atoms in both the compounds. Compound 1 represents the first example of a Ru(II)-thiosemicarbazone complex with a chelating diphosphine and it reveals the stability of a seven membered P,P-chelate ring in the presence of a potentially tridentate pytsc^- ligand.

Full text of DOI:10.1016/j.poly.2006.04.018

Polyhedron 25 (2006) 2897–2903
www.elsevier.com/locate/poly
Thiosemicarbazonates of ruthenium(II): Crystal structures of
[bis(diphenylphosphino)butane]-
[bis(pyridine-2-carbaldehydethiosemicarbazonato)] ruthenium(II) and
[bis(triphenylphosphine)][bis(benzaldehydethiosemicarbazonato)]
ruthenium(II)
a,
a
b
c
c
Tarlok S. Lobana *, Gagandeep Bawa , Ray J. Butcher , Ben-Jie Liaw , Chen W. Liu
a
Department of Chemistry, Guru Nanak Dev University, Amristar 143 005, India
b
Department of Chemistry, Horward University, Washington, DC 20059, USA
Department of Chemistry, National Dong Hwa University, Hualien 974, Taiwan
c
Received 22 February 2006; accepted 16 April 2006
Available online 30 April 2006
Abstract
The reaction of Ru2Cl4(dppb)3 {dppb = Ph2P–(CH2)4–PPh2} with pyridine-2-carbaldehyde thiosemicarbazone {C5H4NAC(H)@N3A
N2HAC(@S)NH2, Hpytsc}, and that of RuCl2(PPh3)3 with benzaldehyde thiosemicarbazone {C6H5AC(H)@N3AN2HAC(@S)ANH2,
Hbtsc}, in the presence of Et3N base led to loss of the –N2H– proton in each case, and yielded [Ru(pytsc)2(dppb)] (1) and
[Ru(btsc)2(Ph3P)2] (2), respectively. The complexes are characterized with the help of analytical data, IR, NMR (1H, 13C, 31P) and single
crystal X-ray study. In both compounds 1 and 2, the thiosemicarbazone ligands coordinate to Ru(II) via the hydrazinic nitrogen (N2) and
sulfur atoms forming four membered rings, and the pyridyl group is pendant in 1. The geometry is distorted octahedral with cis:cis:trans
P,P:N,N:S,S dispositions of donor atoms. Proton NMR confirmed loss of the –N2H– proton in both compounds, and the 31P NMR
spectra reveal the presence of equivalent phosphorus atoms in both the compounds. Compound 1 represents the first example of a
Ru(II)-thiosemicarbazone complex with a chelating diphosphine and it reveals the stability of a seven membered P,P-chelate ring in
the presence of a potentially tridentate pytscꢀ ligand.
Ó 2006 Elsevier Ltd. All rights reserved.
Keywords: Pyridine-2-carbaldehyde thiosemicarbazone; Benzaldehyde thiosemicarbazone; Ruthenium(II); Seven membered rings
1. Introduction
states [1–4]. Chart 1 depicts various thiosemicarbazone
ligands (Htsc) and their complexes with ruthenium(II) [5–
11], having the general formulas, [Ru(tsc)2(Ph3P)2] (3–5)
[7,8,11], [Ru(bpy)2(tsc)](ClO4) (6) [10], [Ru(PPh3)2(Htsc)2]-
(ClO4)2 (7) [9], [Ru(Htsc)(PPh3)2Cl]Cl (8) [6], [Ru(tsc)-
(PPh3)2](ClO4) (9) [5] and [Ru(bpy)2(tsc)](ClO4) (10) [10]
(bpy = 2,20-bipyridine). Complexes 3–6 involve N2, S-chela-
tion (four membered rings), while complexes 7–10 have N3,
S-chelation (five-membered rings). In complexes 8 and 9,
N4 of the pyridine ring is also coordinating.
Thiosemicarbazones{R1R2C@N3AN2HAC(@S)ANR3R4,
Chart 1}, which exhibit thione–thiol tautomerism, possess
several donor atoms and generally bind to metals via N2, S
or N3, S donor atoms forming four- or five-membered rings,
respectively [1–11]. Apart from the bonding and structural
aspects of metal complexes of thiosemicarbazones, they have
biochemical implications either in the free or metal-bonded
In the present paper, we report the synthesis, spectros-
copy and crystal structures of two ruthenium(II) complexes
of [Ru(pytsc)2(dppb)] (1) and [Ru(btsc)2(Ph3P)2] (2). The
*
Corresponding author. Tel.: +91 183 22 57604; fax: +91 183 22 58820.
E-mail address: tarlokslobana@yahoo.co.in (T.S. Lobana).
0277-5387/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2006.04.018

2898
T.S. Lobana et al. / Polyhedron 25 (2006) 2897–2903
H
N2
N2
N1R3R4
S
1
C
3
N
N3
R1R2C2
R1R2C2
C
N1R3R4
SH
thiol
thione
4
5
6
3
2
1
N1R3R4
NO2
OH
NO2
R1
=
N
R1R2C2
4
N3
C
2
N
R2R3
R4
H,H
H
H,H
H
H,H
H,H
C6H5
=
=
H,H
H
H,H
S
H
H
Ru
9
10
CH3
N2
N1R3R4
R1
=
=
=
R'= CH3C(O)-
1
N3
R1R2C2
C
N4
CH3
p-tolyl
p-tolyl
R'
R2, R3
R4
CH3
H
H
S
Ru
8
7
H2
N1R3R4
R1
=
N
1
N3
N
4
CH3
p-tolyl
R1R2C2
N4
C
R2, R3
R4
=
=
H, H
S
Ru
c-C6H11
p-tolyl
Chart 1.
coordination behaviour of these thiosemicarbazones is
investigated under the influence of a potentially P,P-chelat-
ing diphosphine ligand {(C6H5)2P–(CH2)4–P(C6H5)2} in
compound 1, and an unidenate PPh3 ligand in compound
2. To the best of our knowledge, compound 1 is the first
example of a ruthenium(II)–thiosemicarbazone complex
with a diphosphine ligand.
2.2. Synthesis of [Ru(pytsc)2(dppb)] (1)
To a solution of Hpytsc (0.022 g; 0.12 mmol) in methanol
(30 mL) was added solid [Ru2Cl4(dppb)3] (0.05 g;
0.03 mmol) followed by addition of NEt3 (0.5 mL). The
mixture was stirred for about 15 h. The red solid that formed
was filtered, washed with methanol and dried. Crystals were
grown
from
dichloromethane–acetonitrile–methanol.
Yield: 51%, m.p. 172 °C. Anal. Calc. for C42H42N8P2S2Ru Æ
2H2O Æ CH3CN: C, 54.6; H, 5.48; N, 13.02. Found: C, 54.0;
H, 5.04; N, 13.25%. Main IR peaks (KBr, cmꢀ1): m(NH2) +
m(OH2) 3457m, 3360–3300m, 3150w; m(C@N) + dNH2 +
m(C@C) + d(OH2) 1585s, 1573sh, 1562sh; m(C@S) 1047s;
m(P–C) 1093s; electronic spectra (CH2Cl2, kmax/nm, e/L
molꢀ1 cmꢀ1) 391.50 (17600), 328.50 (24580), 245 (40000).
1H NMR (CDCl3): d = 8.80 (s, C2H, 2H), 8.52 (d, C7H,
2H), 7.10–7.66 (m, Ph–H + C4,5,6H, 26H), 5.46 (s, NH2,
4H), 1.26–2.89 (–CH2–, 8 H) ppm; 13C NMR (CDCl3),
d = 182.0 (C1), 155.2 (C3), 149.0 (C7), 145.2 (C2), 138.6–
140.6 (i-C), 135.8 (C5), 132.5 (o-C), 126.9–128.6 (m- and p-
C), 122.4 (C6), 120.7 (C4), 30.1, 23.4 {–(CH2)4-carbons}
2. Experimental
2.1. Materials and techniques
The starting ruthenium(II) complexes, RuCl2(PPh3)3
[12] and Ru2Cl4(dppb)3 [13], were prepared by refluxing
RuCl3 Æ xH2O and the suitable phosphine in dry ethanol
for 5–6 h. Ligands benzaldehyde thiosemicarbazone and
pyridine-2-carbaldehyde thiosemicarbazone were prepared
by the reported methods [15]. Elemental analysis for C, H
and N were carried out using a Thermoelectron FLAS-
HEA1112 analyser. The melting points were determined
with a Gallenkamp electrically heated apparatus. UV
spectra were recorded using an UV-1601PC Shimadzu.
IR spectra were recorded using KBr pellets on a Pye-
Unicam SP3-300 spectrophotometer. 1H NMR spectra
were recorded on a JEOL AL300 FT spectrometer at
300 MHz in CDCl3 with TMS as internal reference. 13C
NMR spectra were recorded at 75.45 MHz with TMS as
internal reference. 31P NMR spectra were recorded at
121.5 MHz with TMP {(CH3O)3P} as external reference
taken as zero position.
ppm; 31P NMR (CDCl3), d = ꢀ57.413 ppm, Dd(dcomplex
ꢀ
d
ligand) = 66.48 ppm.
2.3. Synthesis of [Ru(btsc)2(Ph3P)2] (2)
This complex was prepared by the literature method [9].
To a solution of Hbtsc (0.0186 g; 0.1 mmol) in methanol
(30 mL) was added solid RuCl2(Ph3P)3 (0.05 g; 0.05 mmol)
followed by NEt3 base (0.5 mL). The mixture was stirred
for 2 h and the yellow solid which separated was filtered,

T.S. Lobana et al. / Polyhedron 25 (2006) 2897–2903
2899
Table 1
washed with methanol and dried. The compound was
Crystal data and refinement details for 1 and 2
recrystallized from dichloromethane–methanol solution.
Yield: 60% m.p. 170 °C. Main IR peaks (KBr, cmꢀ1),
m(NH2) 3483s, 3361s; m(C@N) + dNH2 + m(C@C) 1600s,
1577; m(C@S) 1050s, 754 s; m(P–C) 1087s. 1H NMR
(CDCl3) d = 8.88 (s, C2H, 2H), 5.03 (s, NH2, 4H), 6.97–
7.90 (m, C2,4–6,8H + 40H, Ph). 13C NMR (CDCl3) 179.46
(C1), 147.28 (C2), 136.06 (C3), 128.49 (C4,8), 127.23 (C5),
137.24 (i-C), 134.2 (t, o-C ), 128.27 (d, p-C), 126.75 (t, m-C).
1
2
Empirical
formula
M
C42H44.5N8O1.5P2RuS2 C52H46N6P2RuS2
912.49
293(2)
triclinic
982.08
293(2)
triclinic
T (K)
Crystal system
Space group
Unit cell dimensions
ꢀ
ꢀ
P1
P1
31P NMR (CDCl3), d = ꢀ56.015 ppm, Dd(dcomplex
ꢀ
˚
a (A)
9.7303(6)
12.8038(8)
19.3406(11)
85.2610(10)
84.9840(10)
70.4980(10)
2258.9(2)
2
12.715(3)
12.864(3)
16.286(4)
72.184(5)
72.621(5)
65.146(4)
2256.0(10)
2
1.446
0.556
16506
10455 [0.0740]
5602
˚
b (A)
d
ligand) = 57.13 ppm.
˚
c (A)
a (°)
b (°)
c (°)
2.3.1. Ligand NMR data
1
Hpytsc (dmso-d6): H NMR, d = 11.57 (s, N2H, 1H),
8.47 (s, C2H, 1H), 7.2–8.06 (6H, C4,5,6,7 + Ph–H) ppm.
13C NMR 178.05 (C1), 152.17 (C3), 148.42 (C2), 142.38
(C7), 135.56 (C5), 123.09 (C6), 119.73 (C4) ppm; Hbtsc
[17] 1H NMR d = 7.27, 6.60 (s, N1H2, 2H), 10.22
(s, N2H, 1H), 9.26 (s, C2H, 1H), 7.69 (m, C4,8H, 2H),
7.43 (m, C5,6,7H, 3H). 13C NMR 178.86 (C1), 143.94 (C2),
133.99 (C3), 130.87 (C6), 128.96 (C4,8), 127.54 (C5,7); 31P
NMR of dppb: d = ꢀ123.89 ppm; 31P NMR of PPh3,
d = ꢀ113.15 ppm.
3
˚
V (A )
Z
Dcalc (g cmꢀ3
l (mmꢀ1
)
1.348
0.552
)
Reflections collected
31048
Unique reflections [Rint
]
11175 [0.0478]
Reflections with [I > 2r(I)] 6181
Final R indices [I > 2r(I)] R = 0.0448,
wR = 0.1238
R = 0.0778,
wR = 0.1274
and these atoms were treated in an equal population
model. One of the terminal pyridyl groups displayed disor-
der. During refinement the disorder in this group was
resolved. Selected crystal data for compounds 1 and 2 are
given in Table 1.
2.4. X-ray crystallography
Suitable crystals of 1 and 2 were mounted on X-ray dif-
fractomers (Bruker APEX II for 1; CCD area detector for
2), each equipped with graphite monochromators and a
˚
3. Results and discussion
Mo Ka radiation source (k = 0.71073 A). The unit cell
dimensions and intensity data were measured at 293 K.
The structures were solved by direct methods and refined
by full-matrix least-square methods based on F2 with
anisotropic thermal parameters for non-hydrogen atoms,
using Bruker SMART (data collection and cell refinement),
Bruker SHELXTL (data reduction and computing molecular
graphics), SHELXS-97 (structure solution) and SHELXL-97
(structure refinement)] [16]. An empirical absorption cor-
rection was applied. Calculated positions for the H atoms
were used in structure factor (SF) calculations. x scans
were to 56° (2h). In compound 1, one of the pyridine
groups in each pytsc ligand was found to be disordered
3.1. Synthesis and IR spectroscopy
Scheme 1 shows the formation of complexes 1 and 2.
Reaction of Ru2Cl4(dppb)3 {dppb = Ph2P–(CH2)4–PPh2}
with pyridine-2-carbaldehyde thiosemicarbazone {C5-
H4NAC(H)@N3AN2HAC(@S)NH2, Hpytsc}, and that of
RuCl2(PPh3)3 with benzaldehyde thiosemicarbazone
{C6H5AC(H)@N3AN2HAC(@S)ANH2, Hbtsc}, in the
presence of Et3N base led to loss of the –N2H– proton in
each case, and yielded [Ru(pytsc)2(dppb)] (1) and
[Ru(btsc)2(Ph3P)2] (2) [9], respectively. Both the complexes
Scheme 1.

2900
T.S. Lobana et al. / Polyhedron 25 (2006) 2897–2903
are soluble in dichloromethane, chloroform, acetone or tol-
uene, but partially soluble in acetonitrile. The compounds
are stable in air in the solid state; however in solution phase
the complexes turn green on standing for a long time.
Due to the presence of H2O in complex 1, the m(N–H)
region has broad signals at 3457m, 3360–3300m and
3150w, and these peaks are attributed to m(N–H) +
m(O–H). However in complex 2, the m(N–H) region shows
sharp peaks at 3483s and 3361s. The free ligands show very
strong signals due to m(N–H) of the hydrazinic –N2H–
group in the region 3140–3150 cmꢀ1 [14,18]. Thus in com-
plex 2, it is unequivocally established that deprotonation of
the N2H proton occurs after complexation; and in complex
1 due to obscuring of the m(N–H) region by water, depro-
tonation of the N2H proton appears less apparent. It
may be pointed out here that in a series of complexes of
copper(I) with neutral thiosemicarbazones, m(N–H) of the
hydrazinic –N2H– group was clearly visible though shifted
from the free ligand position [19]. Other important IR
peaks are listed in the Section 2. The thioamide bands
m(C@S) + m(C–N) appear in the range 1050–803 cmꢀ1 (cf.
free ligands, 1060–817 cmꢀ1), and on complexation, these
shift to either lower energy or higher energy, but the shifts
are not significant. The appearance of characteristic
m(P–CPh) bands at around 1090 cmꢀ1 indicates the presence
of Ph3P and dppb in the complexes.
crystallized in triclinic crystal systems with the space group
ꢀ
P1 in each case. In compound 1, the thiosemicarbazone
ligand in its deprotonated form (pytscꢀ) is chelating via
its N2, S-donor atoms, thus forming four membered chelate
rings with average Ru(II)–N and Ru(II)–S distances of
˚
˚
2.202 A and 2.418 A, respectively, and the pyridyl group
is pendant. The diphosphine ligand (dppb) is also chelating
via its P,P donor atoms with an average Ru–P distance of
˚
2.264 A (Tables 2 and 3). The donor atoms around the
Ru(II) center occupy cis:cis:trans N,N:P,P:S,S positions.
The angles around the Ru(II) center lie in the range, 65–
163°, with a N2–Ru–S bite angle of 65.85°, N–Ru–N angle
of 83.07° and trans S(1)–Ru–S(2) angle of 163.30°. The
diphosphine ligand dppb forms a seven membered chelate
ring with a P–Ru–P angle of 94.54°. Similarly, compound
2 has average Ru(II)–N, Ru(II)–S and Ru–P distances of
˚
2.145, 2.410 and 2.301 A, respectively. The average bond
angles for N2–Ru–S, N–Ru–N, S–Ru–S, P–Ru–P are
65.80°, 78.80°, 162.54° and 105.37°, respectively. The
geometry of both the complexes is distorted octahedral.
On comparing the bond parameters of 1 and 2, the most
striking difference is found in their Ru–N and Ru–P dis-
tances. Interestingly, the Ru–P distances of 1 are shorter
and its Ru–N distances are longer as compared to those
of 2. This shows the chelating effect of the dppb ligand
which forms stronger Ru(II)–P bonds as compared to
Ru(II)–PPh3 bonds, which in turn affect the Ru(II)–N
bonds trans to Ru–P bonds. The Ru–P distance for 1 is
the shortest among all the complexes listed in Table 3.
The Ru–S bonds remain unaffected by this change as can
be seen by comparing the bonds in both the compounds.
The C–S distances in both the compounds are similar, in
3.2. Crystal structures
The atomic numbering schemes for 1 and 2 are given in
Figs. 1 and 2 respectively, and selected bond angles and
bond lengths are listed in Table 2. Compounds 1 and 2
Fig. 1. The structure of [Ru(pytsc)2(dppb)] (1) with the atomic numbering scheme.

T.S. Lobana et al. / Polyhedron 25 (2006) 2897–2903
2901
Fig. 2. The structure of [Ru(btsc)2(PPh3)2] (2) with the atomic numbering scheme.
Table 2
this is attributed to the presence of bulky PPh3 ligands adja-
cent to each other which causes this angle to deviate towards
the higher side. As a matter of fact, the P–Ru–P bond angle
of 1 is the smallest among all the Ru(II) complexes of thiose-
micarbazones reported to date. The N–Ru–N bond angle in
1 is bigger than that in 2, and this variation is attributed to
the scissoring effect of P–Ru–P angles. The S–Ru–S bond
angles in both the complexes are comparable and are similar
to other complexes reported in the literature (Table 3).
From Table 3, it may be noted that parameters of 2 are very
close to those of complexes 3–5, but different from those of
1. Complexes 1–5, forming four-membered rings, have a
bite angle of ca. 66°, which is small relative to the bite angles
(ca. 81°) of complexes (7–9) which form five-membered
rings.
Compounds 1–5 are analogous with four membered
rings formed by the thiosemicarbazone, the steric bulk
of the phosphines appears to favour N2, S chelation irre-
spective of the substituents on the C2 or N1 atoms. Com-
pound 7 has N3, S chelation with five membered ring
formation, despite the presence of bulky PPh3 ligands in
the cis position, and it is apparent that the presence of
bulky groups at the N1 atom appears to disfavour N2,
S chelation. In 8 and 9 the steric effect of PPh3 is less
demanding in view of the presence of one thiosemicarba-
zone ligand in each complex and this leads to a large
P–Ru–P bond angle and also both have bulky R groups
at N1 and this leads to N3, S chelation. As regards com-
pound 6 and 10, each have two bipyridine ligands and the
only difference lies in the presence of substituents at the
C2 carbon while the substituents at N1are identical (R3,
R4 = H). This difference leads to N2, S chelation in 6
and N3, S chelation in 10.
˚
Selected bond lengths (A) and bond angles (°) for 1 and 2
1
Ru(1)–N(2)
Ru(1)–N(6)
Ru(1)–P(1)
Ru(1)–P(2)
2.187(4)
2.218(3)
2.2582(9)
2.2696(10)
Ru(1)–S(1)
Ru(1)–S(2)
S(1)–C(1)
2.4096(10)
2.4270(10)
1.680(5)
S(2)–C(17)
1.718(4)
N(2)–Ru(1)–N(6)
N(2)–Ru(1)–P(1)
N(6)–Ru(1)–P(1)
N(2)–Ru(1)–P(2)
N(6)–Ru(1)–P(2)
P(1)–Ru(1)–P(2)
N(2)–Ru(1)–S(1)
N(6)–Ru(1)–S(1)
83.06(12)
92.07(9)
163.99(8)
162.42(13)
94.57(9)
94.54(3)
66.06(13)
100.62(9)
P(1)–Ru(1)–S(1)
P(2)–Ru(1)–S(1)
N(2)–Ru(1)–S(2)
N(6)–Ru(1)–S(2)
P(1)–Ru(1)–S(2)
P(2)–Ru(1)–S(2)
S(1)–Ru(1)–S(2)
91.20(3)
97.49(4)
101.64(13)
65.55(9)
100.83(3)
93.10(4)
163.30(4)
2
Ru–N(1A)
Ru–N(1B)
Ru–P(1)
Ru–P(2)
2.141(5)
2.149(5)
2.2977(19)
2.3044(18)
Ru–S(1)
Ru–S(2)
S(1)–C(1A)
S(2)–C(1B)
2.4083(17)
2.4131(17)
1.700(7)
1.712(7)
N(1A)–Ru–N(1B)
N(1A)–Ru–P(1)
N(1B)–Ru–P(1)
N(1A)–Ru–P(2)
N(1B)–Ru–P(2)
P(1)–Ru–P(2)
78.8(2)
N(1B)–Ru–S(1)
P(1)–Ru–S(1)
P(2)–Ru–S(1)
N(1A)–Ru–S(2)
N(1B)–Ru–S(2)
P(1)–Ru–S(2)
P(2)–Ru–S(2)
99.52(14)
87.19(6)
89.16(15)
162.18(14)
162.46(15)
89.02(15)
105.37(7)
65.75(14)
162.54(6)
104.52(6)
100.73(4)
65.85(14)
104.21(6)
85.43(6)
N(1A)–Ru–S(1)
S(1)–Ru(1)–S(2)
˚
the range 1.68–1.71 A, which is shorter than a C–S single
˚
bond of 1.81 A but longer than a C–S double bond of
˚
1.62 A, indicating a partial double bond character [20].
The second major difference lies in the P–Ru–P bond
angle which is smaller for 1 as compared to that in 2, and

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T.S. Lobana et al. / Polyhedron 25 (2006) 2897–2903
Table 3
˚
Comparison of bond lengths (A) and bond angles (°) of 1, 2 and related complexes
Ru–N
Ru–S
Ru–P
S–Ru–S
N–Ru–N
P–Ru–P
N–Ru–S
Ref.
1
2
3
4
5
7
8
9
2.202
2.145
2.181
2.152
2.140
2.146
2.035
1.981
2.418
2.410
2.440
2.426
2.439
2.369
2.386
2.398
2.264
2.301
2.299
2.323
2.314
2.382
2.399
2.371
163.30
162.54
162.77
161.23
160.65
170.81
83.07
78.80
80.42
94.54
105.37
99.24
105.95
97.76
101.74
175.2
165.8
65.85
65.80
65.90
65.74
65.45
81.65
83.3
this work
this work
[7]
[8]
[11]
[9]
[6]
[5]
80.50
81.4
81.5
3.3. NMR spectroscopy
Appendix A. Supplementary material
The signals due to N2H protons in the free ligands (see
Section 2) were absent in the complexes 1 and 2, and it
showed that the ligands are uninegative. The NH2 protons
appear as single peaks in both the complexes due to free
rotation of the N1H2 group along the C1–N1 bond axis,
instead of two broad peaks as observed in the free ligands,
due to the restricted rotation of the N1H2 group along the
C1–N1 bond axis at room temperature [18]. All other pro-
tons appear in the aromatic region as multiplets and over-
lapping signals. The 13C NMR spectra of both the
compounds showed bands due to tscꢀ anions and phos-
phine ligands (cf. Section 2). The C1 carbons of both
ligands move downfield, and it shows coordination via
the S-donor atom, and likewise C2 and C3 move downfield,
but the shift is small. All other tscꢀ carbons show much
smaller shifts. Various signals due to ipso, ortho, meta
and para carbons of the phosphine ligands are resolved
in the complexes. Finally, the 31P NMR spectra of 1 and
2 showed coordination shifts {Dd(dcomplexꢀdligand)} of
66.48 and 57.13 ppm, respectively, revealing that both the
phosphorus atoms are equivalent in each case, and that
the dppb ligand binds more strongly than PPh3, in confor-
mity with the structural data.
Supplementary data is available from CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK, fax: +44 1233 6033,
e-mail:deposit@ccdc.cam.ac.uk on request quoting the
deposition number CCDC 298895 for (1) and 298896 for
(2). Supplementary data associated with this article can
be found, in the online version, at doi:10.1016/j.poly.
2006.04.018.
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Financial assistance from CSIR, New Delhi (F.No. 9/
254(155)-EMR-II) and research facilities to one of us
(Gagandeep) by the University are gratefully
acknowledged.

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