Part 1: 1,3-Dipolar addition of activated alkyne towards coordinated azido group in ruthenium(II) complexes containing η5-cyclichydrocarbons

Article abstract of DOI:10.1016/j.jorganchem.2005.06.016

The indenyl and pentamethylcyclopentadienyl ruthenium(II) complexes [(η⁵-L₃)Ru(L₂)Cl] (L₃ = C ₉H₇, L₂ = dppe (1a), L₂ = dppm (1b) ; L₃ = C₅Me

Full text of DOI:10.1016/j.jorganchem.2005.06.016

Journal of Organometallic Chemistry 690 (2005) 4222–4231
www.elsevier.com/locate/jorganchem
Part 1: 1,3-Dipolar addition of activated alkyne towards
coordinated azido group in ruthenium(II) complexes containing
g5-cyclichydrocarbons
a
b
a,
*
Keisham Sarjit Singh , Carsten Thone , Mohan Rao Kollipara
¨
a
Department of Chemistry, North-Eastern Hill University, Shillong 793022, India
Institut fu¨r Anorganische und Analytische Chemie der Tu, Hagenring, 30,38106 Braunschweig, Germany
b
Received 6 May 2005; received in revised form 8 June 2005; accepted 16 June 2005
Abstract
The indenyl and pentamethylcyclopentadienyl ruthenium(II) complexes [(g5-L3)Ru(L2)Cl] (L3 = C9H7, L2 = dppe (1a),
L2 = dppm (1b); L3 = C5Me5, L2 = dppe (2a); L2 = dppm (2b) (where, dppe= Ph2PCH2CH2PPh2 and dppm = Ph2PCH2PPh2) reacts
with NaN3 to yield the azido complexes [(g5-C9H7)Ru(L2)N3], L2 = dppe (3a), dppm (3b) and [(g5-C5Me5)Ru(L2)N3], L2 = dppe
(4a), dppm (4b), respectively. The azido complexes undergo [3 + 2] dipolar cycloaddition reaction with dimethylacetylenedicarboxy-
late to yield triazole complexes [(g5-C9H7)Ru(L2)(N3C2(CO2Me)2)], L2 = dppe (5a), dppm (5b) and [(g5-C5Me5)Ru(L2)(N3C2-
(CO2Me)2)], L2 = dppe (6a), dppm (6b), respectively. The complexes were fully characterized on the basis of microanalyses,
FT-IR and NMR spectroscopy. The crystal structures of the starting complex (1a) and representative complexes 5a, 5b and 6a have
been established by single X-ray study.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Indenyl; Pentamethylcyclopentadienyl; Dimethylacetylenedicarboxylate; Azide; Ruthenium; Crystal structure
1. Introduction
metal–nitrogen and metal–carbon bonded tetrazoles,
respectively. Interestingly it has been reported that tetra-
zole complexes can also be produce by the reaction of
coordinated nitrile in metal complex with NaN3 [18].
Literature surveys, reveals that most of the cycloaddi-
tion reactions of the azido complexes have been studied
with platinum(II) [11c,16] and palladium(II) metals
[14b,19] although a few have been known in compounds
of other transition metals, viz., rhodium(I) iridium(I),
cobalt(III) and tin(IV) [20]. However, cycloaddition
reaction of coordinated azido complexes in half-sand-
wich systems has not been studied much except a report
appeared in cyclopentadienyl ruthenium cases in recent
years [21]. In contrast, to the best of our knowledge,
such cycloaddition reactions of coordinated azido
complexes in indenyl and pentamethylcyclopentadienyl
systems have not been studied so far. It has been
1,3-Dipolar cycloaddimbtion is a common process in
organic chemistry. The process involves the reaction be-
tween 1,3-dipoles having allyl and dipolarophiles type.
Among various 1,3-dipoles, organic azides are particu-
larly known to be important for the synthesizing hetero-
cyclic compounds [1–6]. By analogy, Dori and Ziolo [7a]
and Fruhauf [7b] have reported that coordinated azide
in metal complexes can also undergo cycloaddition reac-
tion. Thus azido complexes have been reported to react
with nitriles [8–14] and isonitriles [9,15–17] to produce
*
Corresponding author. Tel.: +91 364 272 2620; fax: +91 364 255
0076.
E-mail addresses: kmrao@nehu.ac.in, mrkollipara@yahoo.com
(M.R. Kollipara).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.06.016

K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
4223
reported that the chemistry of indenyl and pentamethyl-
cyclopentadienyl ruthenium complexes are differ from
the analogous cyclopentadienyl ruthenium complex in
certain aspects such as higher reactivity and labile nat-
ure of the organic moieties. The higher reactivity of the
Cp* complexes is attributed to the sterric and inductive
effect whereas in the case of indenyl complexes ring slip-
page nature from g5- to g3- and back to g5- of the inde-
nyl ligand is the solely responsible for the high reactivity
[22]. It is noteworthy that reversible slippage of the me-
tal across the five-membered ring can form a more reac-
tive g3-indenyl tautomer that has both benzenoid
resonance stabilization and accesible coordination site
[23]. Our current study on the reactivity of the indenyl
and Cp* ruthenium bis phosphine complexes, viz.,
[Cp*Ru(PPh3)2Cl] or [(ind)Ru(PPh3)2Cl] (where,
ind = indenyl) towards N-base ligands reveals that the
stability of the indenyl or Cp* ligands are largely depend
on the steric nature of the incoming ligand, such that
reaction of [Cp*Ru(PPh3)2(CH3CN)]+ or [(ind)Ru-
(PPh3)2(CH3CN)]+ with satirically demanded multi-
dented ligand, tetra-2-pyridyl-1,4-pyrazine (tppz),
displaced the organic moiety and isolated the complex
of the type [Ru(tppz)(PPh3)2(CH3CN)]+ [24]. However,
the reaction with less sterric N-base ligand, the organic
moiety remain intact to the metal and thus forming com-
plex of the type [g5-L3)Ru(PPh3)(L2)]+ [25] (where
L3 = indenyl or Cp*). In general, sterically demanded
multidentate ligand displaced them from the complexes.
The part 1 of this communication, we described the syn-
theses of azido complexes of indenyl and pentamethylcy-
clopentadienyl ruthenium(II) and their reactions with
dimethylacetylenedicarboxylate to generate triazole
complexes (5a,b and 6a,b). The spectral and structural
characterization of the complexes has been discussed.
(Aldrich) were used as received. NMR spectra were re-
corded on an AMX-400 MHz spectrometer at 400.13
(1H), 161.97 (31P) or 100.61 MHz (13C) with SiMe4 or
85% H3PO4 as internal references and coupling con-
stants are given in hertz. Infrared spectra were recorded
as a KBr pellets on a Perkin–Elmer Model 983 spec-
trometer. Elemental analyses were carried out at the Re-
gional Sophisticated Instrumentation centre (RSIC)
Shillong, using a Perkin–Elmer 2400 CHN/S analyzer.
Electronic spectra were recorded on a Hitachi-330 spec-
trophotometer in dichloromethane at ca. 10ꢀ4 M. The
precursor complexes [(g5-C9H7)Ru(dppe)Cl] (1a) and
[(g5-C9H7)Ru(dppm)Cl] (1b) were prepared following
a literature method [27] while the complexes [(g5-
C5Me5)Ru(dppe)Cl] (2a) and [(g5-C5Me5)Ru(dppm)Cl]
(2b) were prepared by slight modification of the reported
method [28] as described below. 13C{1H} NMR data for
the indenyl complexes are presented in Table 1. The fol-
lowing atom labeling scheme is used for the 1H and
13C{1H} NMR spectroscopic data of indenyl complexes.
2.1. Synthesis of precursor complex [(g5-C5Me5)-
Ru(dppe)Cl] (2a)
A two neck round bottom flask was charged with
[(g5-C5Me5)Ru(PPh3)2Cl] (100 mg, 0.125 mmol), dppe
(60 mg, 0.150 mmol) and 50 ml of toluene was added.
The mixture was heated to reflux under nitrogen atmo-
sphere for 15 h and cooled to room temperature. The
solvent was removed under reduced pressure and the so-
lid residue was purified by column chromatography over
alumina. A bright yellow band was collected when
eluted with dichloromethane which on concentration
2. Experimental
All solvents were dried in appropriate drying agents
and distilled prior to use [26]. RuCl3 Æ 3H2O (Arora
Matthey Limited) and dimethylacetylenedicarboxylate
Table 1
13C{1H} NMR data for the indenyl complexesa,b
Complex
g5-C9H7
Others
C-1,3
C-2
C-3a,7a
Dd(C-3a,7a)b
C-4,5
C-6,7
3a
3b
5a
65.08
63.09
66.35
87.71
87.14
93.60
109.33
109.07
108.81
ꢀ21.37
ꢀ21.63
ꢀ21.89
124.63
123.20
125.13
125.78
125.65
127.51
27.86 (m, P(CH2)2P), 127.66–133.73 (m, PPh2)
49.40 (t, JCꢀP = 19.7, (P(CH2)P)), 128.32–137.69 (m, PPh2)
29.42 (m, P(CH2)2P), 51.21 (s, (OCH3)), 127.66–133.73 (m, Ph),
138.12 (C(CO2 Me)), 167.8 (s, (CO2))
5b
66.50
89.44
108.76
ꢀ21.94
124.98
125.18
49.66 (t, JCꢀP = 21.4, (P(CH2)P)), 51.11 (s, (OCH3)),
127.59–134.61 (m, Ph), 138.04 (C(CO2 Me)), 168.72 (s, (CO2))
a
Spectra recorded in CDCl3; d in ppm and J in Hz. Abbreviations: s, singlet; t, triplet; m, multiplet.
Dd(C-3a,7a) = d(C-3a,7a)(g-indenyl complex) ꢀ d(C-3a,7a (sodium indenyl)), d(C-3a, 7a) for sodium indenyl, 130.70 ppm.
b

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K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
to ca. 5 ml and addition of excess hexane induced a
bright yellow solid of the complex (2a). Yield: 70 mg,
83%.1H NMR (CDCl3, d): 7.22–7.69 (m, 20H, 4Ph);
2.34–2.04 (2m, 4H, PCH2CH2P), 1.42 (s, 15H, C5Me5).
31P{1H} (CDCl3, d): 73.46.
cooled, the solvent was removed by rotary evaporator,
the solid residue was extracted with CH2Cl2 and the ex-
tract was filtered. The filtrate on concentration to ca. 5
ml and addition of hexane induced blood red solid.
The solid was centrifuged and washed with hexane to
give 89 mg, 90% yield of the complex. Anal. Calc. for
C34H29N3P2Ru: C, 63.49; H, 4.51; N, 6.53. Found: C,
63.25; H, 4.82; N, 6.23%.
2.2. Synthesis ofcomplex[(g5-C5Me5)Ru(dppm)Cl] (2b)
The complex was prepared by following the same
procedure as (2a) using dppm instead of dppe and
refluxing for 18 h. Yield: 66 mg, 80%.
The spectroscopic data for the complex is as follows:
IR (KBr, cmꢀ1): m(N3) 2030 (vs).
UV–Vis (k, nm): 470.
1H NMR (CDCl3, d): 7.75–7.25 (m, 20H, 4Ph); 4.92–
4.02 (2m, 2H, PCH2P), 1.63 (s, 15H, C5Me5). 31P{1H}
(CDCl3, d): 12.34.
1H NMR (CDCl3, d): 7.64 (dd, 2H, J(HH) = 6.36,
J(HH) = 3.32, (H-5,6 or H-4,7)); 7.38–7.25 (m, 20H,
4Ph, Ph2PCH2PPh2, H-5,6, indenyl), 4.98 (dt, 2H,
J(HH) = 14.68, J(HH) = 10.48, PCHaCHbP), 4.84 (br,
s, 3H, H-1,2,3), 4.12 (dt, 2H, J(HH) = 11.36, J(HH) =
11.16 Hz, PCHaHbP). 31P{1H} NMR (CDCl3, d): 14.33.
2.3. Preparationofcomplex[(g5-C9H7)Ru(dppe)N3](3a)
Two routes were used to synthesize this complex.
Route (a): To a solution of [(g5-C9H7)Ru(dppe)Cl]
(100 mg, 0.153 mmol) in 30 ml ethanol, was added
NaN3 (49 mg, 0.73 mmol). The resulting solution was
refluxed for 4 h during this time the color of the solution
progressively changed from yellow orange to dark red.
The solution was then left at room temperature over-
night. The red crystals that deposited were collected by
filtration, washed with cold ethanol and air-dried. Addi-
tional product may be obtained by evaporating the fil-
trate under reduced pressure and extracting with
CH2Cl2 and filtered (overall yield = 86 mg, 86%).
Route (b): To a solution of [(g5-C9H7)Ru(dppe)Cl]
(100 mg, 0.153 mmol) in 30 ml of ethanol, was added
NaN3 (49 mg, 0.76mmol). The resulting solution was re-
fluxed for 3 h. The solution was cooled to room temper-
ature. The solvent was removed in rotary-evaporator,
the solid residue was extracted with CH2Cl2 and filtered
to remove NaCl and excess NaN3. The filtrate on con-
centration to ca. 5 ml and addition of excess hexane gave
a bright red crystalline solid. Yield: 83 mg, 83%. Anal.
Calc. for C35H31N3P2Ru: C, 63.96; H, 4.72; N, 6.39.
Found: C, 63.28; H, 4.03, N, 6.53%.
2.5. Preparation of complex [(g5-C5Me5)Ru(dppe)N3]
(4a)
A 100 ml round bottom flask was charged with [(g5-
C5Me5)Ru(dppe)Cl] (100 mg, 0.149 mmol), NaN3 (48
mg, 0.745 mmol) and ethanol (40 ml). The yellow orange
suspension was refluxed for 4 h during this time solution
became bright yellow. The reaction mixture was cooled
to room temperature and the solvent was removed by
rotary evaporator. The solid residue was extracted with
5 ml dichloromethane and filtered to remove NaCl and
excess NaN3. The filtrate was concentrated to ca. 5 ml
and excess of hexane was added. On reduction the vol-
ume of the solution in rotary evaporator a yellow crys-
talline solid was separated out. The solid was collected
and dried in vacuum. Yield: 88 mg, 87%. Anal. Calc.
for C36H39N3P2Ru: C, 63.89; H, 5.76; N, 6.21. Found:
C, 63.28, H, 5.17; N, 5.98%.
Spectroscopic data for the complex 4a are as follows:
IR (KBr, cmꢀ1): m(N3) 2030 (vs).
1H NMR (CDCl3, d): 7.69–7.20 (m, 20H, 4Ph,
Ph2PCH2CH2PPh2), 2.52–2.41 (m, 2H, Ph2P(CH2)2
PPh2), 2.13–2.04 (m, 2H, Ph2P(CH2)2PPh2), 1.45 (s,
15H, C5Me5).
Spectroscopic data for the complex (3a) is as follows:
IR (KBr, cmꢀ1): m(N3) 2024 (vs).
UV–Vis (k, nm): 490.
13C{1H} NMR (CDCl3, d): 138.04–127.79 (m, Ph),
1H NMR (CDCl3, d): 7.21–7.35 (m, 24H, 4Ph, H-4,7
and H-5,6, indenyl); 4.96 (br, 1H, H-2, indenyl); 4.48 (d,
2H, J(HH) = 3.4, H-1,3, indenyl), 2.56–2.26 (2m, 4H,
Ph2PCH2CH2PPh2). 31P{1H} NMR (CDCl3): 84.27.
89.67 (s, C5Me5 (ring C)), 28.67 (t, P(CH2)2P, JC–P =
21.5), 9.66 (s, C5Me5, (CH3)). 31P{1H} (CDCl3, d): 75.74.
2.6. Preparation of the complex [(g5-C5Me5)-
Ru(dppm)N3] (4b)
2.4. Preparation of complex [(g5-C9H7)Ru(dppm)N3]
(3b)
This complex was prepared in analogy to the complex
(4a), [(g5-C5Me5)Ru(dppm)Cl] (200 mg, 0.3 mmol),
NaN3 (99 mg, 1.5 mmol) EtOH (40 ml) were used.
Recrystallization from dichloromethane and hexane
gave yellow crystals of complex 4b. Yield: 87%, 176
mg. Anal. Calc. for C35H37N3P2Ru: C, 63.43; H, 5.58;
N, 6.34. Found: C, 63.98; H, 5.36; N, 6.12%.
A round bottom flask was charged with [(g5-
C9H7)Ru(dppm)Cl] (100 mg, 0.157 mmol), NaN3 (51
mg, 0.786 mmol) and 40 ml of ethanol. The resulting
solution was refluxed for 5 h. The color of the solution
changed from red to brick red. After the mixture was

K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
4225
IR (KBr, cmꢀ1): m(N3) 2037 (vs).
mmol) or (4b) (146 mg, 0.220 mmol) was added dimeth-
ylacetylenedicarboxylate (155 mg, 1.10 mmol) and
CH2Cl2 (20 ml). The mixture was stirred at room tem-
perature then the solution was reduced to 3 ml under re-
duce pressure. To this solution was added excess of
hexane. The volume of the resulting solution was re-
duced in rotary evaporator giving a yellow solid. The
yellow solid was collected, washed with hexane 2 · 10
ml and dried under vacuum to give triazole complexes
(6a) and (6b). Yield (%), reaction time, color, analytical
and spectroscopic data are as follows: L2 = dppe (6a):
89 (161 mg, 0.196 mmol), 14 h, yellow.
1H NMR (CDCl3, d): 7.75–7.28 (m, 20H, 4Ph,
Ph2CH2Ph2), 4.92–4.83 (dt, 1H, J(HH) = 14.84,
J(HH) = 9.64 Hz, PCHaCHbP), 4.12–4.02 (dt, 1H,
J(HH) = 14.88, J(HH) = 10.84, PCHaCHbP), 1.68(s,
15H, C5Me5).
13C {1H}(CDCl3, d): 136.32–128.01 (m, Ph), 88.89
(s, C5Me5(ring)), 49.59 (t, JC–P = 18.9, P(CH2)P), 10.36
(s, C5Me5(CH3)). 31P{1H} (CDCl3, d): 12.44.
2.7. Preparation of indenyl triazole complexes
[(g5-C9H7)Ru(L2)(N3C2(CO2Me)2)], L2 = dppe (5a),
dppm (5b)
Anal. Calc. for C42H45N3O4P2Ru: C, 61.55; H, 5.49;
N, 5.12. Found: C, 60.94; H, 5.28; N, 5.26%. IR (KBr,
cmꢀ1): m(C@O) 1732 (vs), m(N@N) 1438(s), m(C–O) 1295 (m).
1H NMR (CDCl3, d): 7.69–7.07 (m, 20H, 4Ph,
Ph2P(CH2)2PPh2), 3.60 (s, 6H, 2CH3), 3.53–2.51 (2m,
4H, P(CH2)2P), 1.43 (s, 15H, C5Me5).
General procedure: To a round bottom flask charged
with corresponding azido complex (3a) (164 mg, 0.25
mmol) or (3b) (160 mg, 0.25 mmol) was added dimethyl-
acetylene-dicarboxylate (177 mg, 1.25 mmol) and
CH2Cl2 (20 ml). The mixture was stirred at room temper-
ature then the solution was reduced to ca. 3 ml in rotary
evaporator. To this solution was added 30 ml of hexane,
whereby the compound precipitated out as a yellow so-
lid. The solid was collected by centrifuged and washed
with 2 · 20 ml of hexane and dried under vacuum to gave
the N(2)-bound triazole complex [(g5-C9H7)Ru(L2)–
(N3C2(CO2Me)2)] (5a) and (5b). Yield (%), reaction time,
color, analytical and spectroscopic data are as follows:
L2 = dppe (5a): 92, (183 mg, 0.229 mmol); 8 h, yellow,
Anal. Calc. for C41H37N3O4P2Ru: C, 61.59; H, 4.63; N,
5.25. Found: C, 61.24; H, 4.23; N, 5.38%. IR (KBr,
cmꢀ1): m(C@O) 1732 (vs), m(N@N) 1438(s), m(CO) 1295 (m).
UV–Vis (k, nm): 423.
13C{1H} NMR (CDCl3, d): 162.13(CO2), 138.19
(C(CO2Me), 134.79–127.44(Ph), 91.70 (ring
C
(C5Me5)), 51.01 (OCH3), 31.27 (t, P(CH2)2P,
JC–P = 33.7), 9.64 (s, CH3 (C5Me5)). 31P{1H} NMR
(CDCl3, d): 87.32.
L2 = dppm (6b): 87 (154 mg, 0.191 mmol), 18 h, yel-
low, Anal. Calc. for C41H43N3O4P2Ru: C, 61.13; H,
5.34; N, 5.21. Found: C, 60.82; H, 5.14; N, 4.98%.
IR (KBr, cmꢀ1): m(C@O) 1732 (vs), m(N@N) 1440(s),
m(C–O) 1268 (m).
1H NMR (CDCl3, d): 7.69–7.11 (m, 20H, Ph),
5.35–5.26 (dt, 1H, J(HH) = 14.6Hz, J(HH) = 11.6,
PCHaCHbP), 4.99–4.93 (dt, 1H, J(HH) = 14.68,
J(HH) = 9.44, PCHaCHbP), 3.60 (s, 6H, 2(OCH3)),
1.65 (s, 15H, (C5Me5)).
1H NMR (CDCl3, d): 7.40–6.67 (m, 24H, 4Ph,
Ph2P(CH2)2PPh2, H-5,6 and H-4,7, indenyl), 4.87 (t,
1H, J(HH) = 3.8, indenyl), 4.72 (d, 2H, J(HH) = 3.62,
indenyl), 3.62 (s, 6H, OCH3), 3.14–3.11 (m, 2H,
P(CH2)2P), 2.46–2.44 (m, 2H, P(CH2)2P).
13C{1H} NMR (CDCl3, d): 162.49 (CO2), 138.42
(C(CO2Me)), 137.15–127.50 (Ph), 90.66 (ring
C(C5Me5)), 51.48 (t, JC–H = 21.5, (OCH3)), 30.88
(PCH2P), 10.31 (CH3(C5Me5)). 31P{1H} (CDCl3, d):
15.46.
31P{1H} NMR (CDCl3, d): 91.16.
L2 = dppm (5b): 89 (174 mg, 0.221 mmol), 15 h, yel-
low orange. Anal. Calc. for C40H35N3O4P2Ru: C, 61.16;
H, 4.46; N, 5.35. Found: C, 60.87; H, 4.25; N, 5.12%.
IR (KBr, cmꢀ1): m(C@O) 1725, m(N@N) 1440 (m), m(CO)
1275 (m).
3. Structure analysis and refinement
X-ray quality crystals of all the four complexes 1a,
5a, 5b and 6a were grown by slow diffusion of hexane
into dichloromethane solution of the complexes. The
X-ray intensity data were measured at 133(2) K for com-
plexes 1a, 5a, 5b and 6a on a Bruker Smart 1000 CCD
diffractometer, using graphite monochromated Mo Ka
UV–Vis (k, nm): 425.
1H NMR (CDCl3, d): 7.59–7.01 (m, 24H, Ph,
Ph2P(CH2)PPh2, H-5,6, H-4,7, indenyl), 5.29–5.19 (m,
1H, PCHaCHbP), 4.96–4.87 (br, s, 3H, H-1,2,3, indenyl),
3.91–3.75 (m, 1H, PCHaCHbP), 3.63 (s, 6H,
2(OCH3)).31P{1H} NMR (CDCl3, d): 14.56.
˚
radiation (k = 0.71073 A). Intensity data were corrected
for Lorentz and polarization effects and absorption
correction [29] The structures were solved by direct
methods (SHELXS-97) [30] and refined by full-matrix
least-squares base on F2 using SHELXL-97 [31]. The
weighting scheme used w ¼ 1=½r2ðF 2oÞ þ aP2 þ bPꢁ;
where P ¼ ðF 2o þ 2F c2Þ=3. Non-hydrogen atoms were
refined anisotropically and hydrogen atoms were refined
2.8. Preparation of pentamethylcyclopentadienyl
N(2)-bound triazole complexes [(g5-C5Me5)Ru(L2)-
(N3C2(CO2Me)2)], L2 = dppe (6a), dppm (6b)
General procedure: To a round bottom flask charged
with corresponding azido complexes (4a) (150 mg, 0.221

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K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
Table 5
using a ‘‘riding’’ model or as rigid groups (methyls).
Refinement converged at a final R = 0.0235, 0.0366,
0.0240 and 0.0331 for complex 1a, 5a, 5b and 6a, respec-
tively, (for observed data F), and wR2 = 0.0639, 0.0998,
0.0626 and 0.0814 for complex 1a, 5a, 5b and 6a, respec-
˚
Selected bond lengths (A) and angles (ꢁ) for the compound 6a
Ru–Ca
1.8798(8) Ru–N(2)
2.2923(5) Ru–P(2)
1.332(2)
1.350(3)
1.196(3)
1.392(3)
2.1010(16)
2.2993(5)
1.344(2)
1.340(3)
1.202(3)
1.532(3)
Ru–P(1)
N(1)–N(2)
N(1)–C(15)
C(14)–O(1)
C(15)–C(16)
N(2)–N(3)
N(3)–C(16)
C(17)–O(3)
C(11)–C(12)
Table 2
P(1)–Ru–P(2)
Ru–N(2)–N(1)
N(2)–N(1)–C(15)
84.294(18) N(1)–N(2)–N(3)
112.45(15)
124.1(2)
105.63(16)
a
˚
Selected bond lengths (A), angles (ꢁ) and slip parameter D for the
compound 1a
122.97(12)
105.92(16)
Ru–N(2)–N(3)
N(2)–N(3)–C(16)
N(3)–C(16)–C(15) 108.33(17)
C(15)–C(16)–C(17) 130.09(19)
Ru–Cb
Ru–Cl
Ru–P(1)
Ru–P(2)
1.8960(6)
2.4331(4)
2.2314(4)
2.2970(4)
C(12)–C(13)
C(10)–C(11)
C(2)–P(2)
1.375(2)
1.368(2)
1.8353(14)
1.8590(14)
a
Centroid of C(1), C(2), C(3), C(4), C(5).
C(1)–P(1)
Table 6
Hydrogen bonds (A) and (ꢁ) for compounds 5b and 6a
DM–C
0.158
˚
P(1)–Ru–P(2)
P(1)–Ru–Cl
P(2)–Ru–Cl
a
82.171(13)
91.509(13)
84.087(13)
Ru–P(1)–C(1)
Ru–P(2)–C(2)
112.30(5)
106.83(4)
D–Hꢂ ꢂ ꢂA
Compound 5b
d(D–H) d(Hꢂ ꢂ ꢂA) d(Dꢂ ꢂ ꢂA)
\(DHA)
C(45)–H(45)ꢂ ꢂ ꢂO(3)#1
C(22)–H(22)ꢂ ꢂ ꢂO(3)#2
0.95
0.95
2.43
2.68
2.62
2.60
2.64
2.66
2.58
3.2141(18) 139.8
3.4030(17) 133.9
3.3703(19) 133.2
3.453(2)
3.510(2)
3.4837(18) 145.2
D = davg (Ru–C(14), C(18)) ꢀ davg (Ru–C(15), C(17)).
b
Centroid of C(14), C(15), C(16), C(17), C(18).
C(13)–H(13C)ꢂ ꢂ ꢂO(2)#3 0.98
C(3)–H(3)ꢂ ꢂ ꢂO(4)#4
C(33)–H(33)ꢂ ꢂ ꢂO(3)#4
C(2)–H(2)ꢂ ꢂ ꢂO(2)#4
0.95
0.95
0.95
149.4
152.7
Table 3
C(16)–H(16C)ꢂ ꢂ ꢂO(1)#5 0.98
Compound 6a
3.536(3)
163.8
˚
Selected bond lengths (A), angles (ꢁ), torsion angles (ꢁ) and slip
parameter Da for the compound 5a
C(26)–H(26)ꢂ ꢂ ꢂO(1)#6
0.95
0.95
2.41
2.64
3.122(3)
3.267(3)
131.2
123.9
Ru–Cb
1.888(1)
2.2396(6)
1.336(3)
1.348(3)
1.205(3)
0.175
Ru–N(1)
Ru–P(2)
N(1)–N(3)
N(3)–C(3)
C(4)–O(1)
C(3)–C(6)
2.0904(18)
2.2720(6)
1.336(3)
1.351(3)
1.200(3)
1.395(3)
C(43)–H(43)ꢂ ꢂ ꢂO(3)#6
Ru–P(1)
N(1)–N(2)
N(2)–C(6)
C(7)–O(3)
DM–C
Symmetry transformations used to generate equivalent atoms: #1: ꢀx,
ꢀy, ꢀz; #2: x + 1, y, z; # 3: ꢀx + 1, ꢀy, ꢀz + 1; #4: ꢀx + 1, ꢀy + 1,
ꢀz + 1; #5: ꢀx, ꢀy, ꢀz + 1; #6: x, ꢀy + 1/2, z ꢀ 1/2.
P(1)–Ru–P(2)
N(1)–N(2)–C(6)
N(1)–Ru–P(1)
N(2)–C(6)–C(3)
N(3)–C(3)–C(4)
P(2)–C(2)–C(1)
a
84.92(2)
105.83(18)a
86.38(5)
107.67(19)
120.7(2)
N(2)–N(1)–N(3)
N(1)–N(3)–C(3)
N(1)–Ru–P(2)
N(3)–C(3)–C(6)
N(2)–C(6)–C(7)
P(1)–C(1)–C(2)
112.95(17)
108.29(19)a
89.73(5)
108.29(19)
121.2(2)
tively, (all data on F2). Summary of crystal structures
data collection and refinement parameters are given in
Table 7 and selected bond lengths and angles have been
given in Tables 2–5.
111.1(3)
108.9(3)
D = davg(Ru–C(13),C(17)) ꢀ davg(Ru–C(14),C(16)).
b
Centroid of C(13), C(14), C(15), C(16), C(17).
4. Results and discussion
4.1. Synthetic considerations and spectral studies
Table 4
4.1.1. Preparation of azido complexes [(g5-C9H7)-
Ru(L2)N3] and [(g5-C5Me5)Ru(L2)N3]
a
˚
Selected bond lengths (A), angles (ꢁ) and slip parameter D for the
compound 5b
The reaction of [(g5-C9H7)Ru(L2)Cl] (L2 = dppe(1a),
dppm(1b)) with fivefold excess of NaN3 in refluxing eth-
anol gives indenyl azido complexes 3a and 3b in good
yield (86% and 90%) (Scheme 1). Under similar reaction
conditions, [(g5-C5Me5)Ru(L2)Cl] {L2 = dppe (2a),
dppm (2b)} reacts with excess of NaN3 affords
corresponding azido complexes 4a and 4b (87%)
(Scheme 1). All these azido complexes are air stable
and soluble in chlorinated solvents. The complexes have
been characterized by microanalyses, infrared and
NMR (1H), 31P{1H}, 13C{1H} spectroscopy (details
are given in Section 2). The formation of azido
complexes is confirmed by the appearance of strong
Ru–Cb
Ru–P(1)
N(1)–N(2)
N(2)–C(11)
C(12)–O(2)
C(11)–C(14)
1.8837(6)
2.3229(3)
1.3362(15) N(1)–N(3)
1.3467(15) N(3)–C(14)
1.3369(16) C(15)–O(3)
1.3989(17) DM–C
Ru–N(1)
Ru–P(2)
2.0893(10)
2.2427(3)
1.3380(14)
1.3493(16)
1.2026(16)
0.123
P(1)–Ru–P(2)
Ru–P(1)–P(2)
N(1)–N(2)–C(11) 105.67(10)
72.003(12)
52.614(10)
N(2)–N(1)–N(3)
Ru–P(2)–P(1)
N(1)–N(3)–C(14) 105.37(10)
N(1)–Ru–P(2)
Ru–P(2)–C(10)
113.03(10)
55.384(10)
N(1)–Ru–P(1)
Ru–P(1)–C(10)
P(1)–C(10)–P(2)
a
90.46(3)
95.09 (4)
93.16(6)
90.22(3)
98.04(4)
D = davg (Ru–C(5),C(9)) ꢀ davg (Ru–C(6),C(8)).
b
Centroid of C(5), C(6), C(7), C(8), C(9).

K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
4227
Table 7
Summary of crystal structure determination and refinement for complexes 1a, 5a, 5b and 6a
Complex
1a
5a
5b
6a
Empirical formula
Formula weight
T (K)
C35H37ClP2Ru
650.06
133(2)
C41H37N3O4P2Ru
798.75
133(2)
C40H35N3O4P2Ru
784.72
133(2)
C42H45N3O4P2Ru
818.82
133(2)
˚
k (A)
0.71073
0.71073
0.71073
0.71073
Crystal system
Space group
Monoclinic
P21/c
Monoclinic
P21/c
Triclinic
Monoclinic
P21/c
ꢀ
P1
Unit cell dimensions
˚
a (A)
13.2690(8)
10.6998(6)
21.0635(12)
13.0622(8)
12.2684(8)
23.3982(14)
11.5173(6)
12.6026(8)
14.3999(8)
91.852(3)
109.856(3)
114.218(3)
1756.58(17)
2
1.484
0.584
804
0.39 · 0.38 · 0.18
1.53–30.03
ꢀ16 6 h 6 16,
ꢀ17 6 k 6 17,
ꢀ20 6 l 6 20
35066
12.5815(8)
13.5221(8)
22.3516(14)
˚
b (A)
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
107.947(3)
104.963(3)
97.701(3)
3
˚
V (A )
2845.0(3)
4
1.518
0.782
1328
0.38 · 0.34 · 0.21
1.61–30.03
ꢀ18 6 h 6 18,
ꢀ15 6 k 6 15,
ꢀ29 6 l 6 29
59146
3622.5(4)
4
1.465
0.568
1640
0.25 · 0.19 · 0.18
1.80–30.03
ꢀ18 6 h 6 18,
ꢀ17 6 k 6 17,
ꢀ32 6 l 6 32
75429
Z
4
Dcal (Mg/m3)
1.443
0.548
1696
0.28 · 0.22 · 0.17
1.63–30.03
ꢀ17 6 h 6 17,
ꢀ19 6 k 6 19,
ꢀ31 6 l 6 31
78441
Absorption coefficient (mmꢀ1
F(000)
)
Crystal size (mm3)
h Range for data collection (ꢁ)
Index ranges
Reflections collected
Independent reflections (Rint
Completeness to h (ꢁ)
Absorption correction
)
8313 (0.0246)
30.00
Semi-empirical from equivalents
10589 (0.0470)
30.00
10230 (0.0185)
30.00
11011 (0.0549)
30.00
Maximum and minimum transmission
Refinement method
0.8530 and 0.7452
0.9047 and 0.7965
0.9021 and 0.7326
0.9126 and 0.7896
Full-matrix least-squares on F2
Data/restraints/parameters
Goodness-of-fit on F2
8313/0/352
1.068
10589/21/481
1.063
10230/0/453
1.023
11011/0/476
1.056
Final R indices [I > 2r(I)]
R1 = 0.0235,
wR2 = 0.0598
R1 = 0.0291,
wR2 = 0.0639
0.654 and ꢀ0.309
R1 = 0.0366,
wR2 = 0.0882
R1 = 0.0562,
wR2 = 0.0998
1.681 and ꢀ0.539
R1 = 0.0240,
wR2 = 0.0602
R1 = 0.0275,
wR2 = 0.0626
0.683 and ꢀ0.404
R1 = 0.0331,
wR2 = 0.0718
R1 = 0.0539,
wR2 = 0.0814
0.700 and ꢀ0.284
R indices (all data)
ꢀ3
˚
Largest difference in peak and hole (e A
)
absorption band corresponding to the asymmetric m(N3)
in the region 2024–2037 cmꢀ1 in the FT-IR spectra of
the complexes. The UV–Vis spectra for the azido com-
plexes under investigation were measured in dichloro-
methane at ca. 10ꢀ4 M. The broad band were
observed in the range kmax = 470–490 nm which are
assignable to the low energy transition (MLCT) band.
The 31P{1H} spectra of the indenyl as well as pentam-
ethylcyclopentadienyl complexes show a single reso-
nance at d 84.27 (3a), 14.33 (3b), 75.74 (4a) and 12.44
(4b) which is consistent with the chemical equivalence
of both the phosphorous atoms. It is notable that the
31P{1H} spectra of the dppe in the complexes were reso-
nance at low field while that of dppm in the upfield re-
gion in both indenyl and Cp* complexes which are
comparable with those of reported values [27,32,33].
The proton NMR spectra of the complexes are well con-
sisted with the proposed structures. In the 1H NMR
spectra of the indenyl complexe (3a) the resonance for
the H-2 proton of the indenyl appeared in the downfield
region at d 4.96 while that of H-1,3 resonate at d 4.48 as
doublet (J(HH) = 3.4 Hz). However, in the case of 3b
the resonance of these protons appeared as unresolved
signal at d 4.84. The –CH2– protons of dppe in the com-
plexes 3a and 4a exhibited two multiplets in the range of
d 2.26–2.56 (3a) and d 1.04–2.52 (4a), respectively. While
CH2 of dppm protons in the complexes 3b and 4b
resonate as doublet of triplet at d 4.98 (JHH = 10.32,
JH–P = 10.48
Hz)
and
4.02
[J(HH) = 14.88,
J(HP) = 10.84 Hz], respectively. A multiplet in the region
d 7.21–7.38 was observed in the spectra of the complexes
3a and 3b corresponding to the protons of phenyl and
H-5, 6 and H-4, 7 of the indenyl group. As expected
the 13C NMR of the complexes displayed a triplet, occa-
sionally as unresolved peak for the CH2 carbon of dppe
at ca. d 27.86 and 28.67 for 3a and 4a while that of dppm
appeared as triplet at d ca. 49.40 (3b) [JC–P = 19.7 Hz]
and 49.59 (4b) [JC–P = 21.4 Hz], respectively.
Indenyl carbon resonances (Table 1) have also been
assigned; they are in accordance with the proposed
g5-coordination [34]. As have been proven previously,
the parameter Dd(C-3a, 7a) = d(C-3a, 7a) (g-indenyl

4228
K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
Scheme 1.
complex) ꢀ d(C-3a, 7a-sodium indenyl) can be used as
indication of the indenyl distortion [35]. The calculated
values of Dd(C-3a, 7a) are given in Table 1. The calcu-
lated values for the complexes 3a and 3b are d ꢀ21.37
and ꢀ21.63, respectively and the values are indicative
of a slight distortion of the indenyl ring.
in due course. Further, our current study on the azido
complexes of arene ruthenium with various activated
acetylenes reveals that such triazole complexes are read-
ily generate from the neutral ruthenium azido com-
plexes, but the reaction did not undergo in cationic
ruthenium azido complexes. The work is in under pro-
gress. The complexes were characterized by FT-IR,
NMR (1H, 31P{1H}, 13C {1H}) spectroscopy (details
are given in Section 2). Thus, the IR spectra (KBr) of
the complexes show strong absorption band characteris-
tic of m(C@O) at 1732 while m(C–O) and m(N@N) were ob-
4.1.2. Preparation of triazole complexes, [(g5-C9H7)-
Ru(L2)N3C2(CO2Me)2)] and [(g5-C9H7)Ru(L2)-
(N3C2(CO2Me)2)]
N(2)-bound 4,5-bis(methoxycarbonyl)-1,2,3-triazole
complexes, [(g5-C9H7)Ru(L2)(N3C2(CO2Me)2)], L2 =
dppe (5a), dppm (5b) and [(g5-Cp*)Ru(L2)(N3C2-
(CO2Me)2)], L2 = dppe (6a), dppm = 6b, respectively,
are readily prepared in quantitatively good yield (87–
92%) by the treatment of complexes (3a-b) or (4a-b) with
sixfold excess of dimethylacetylenedicarboxylate in
CH2Cl2 at room temperature. But attempt to syntheses
corresponding triazole complexes of bis triphenyl phos-
phine [(g5-L3)Ru(PPh3)2(N3C2(CO2Me)2)], L3 = C9H7
or C5Me5, were not successful so far. It is possible that
the more satirically demanding bis triphenylphosphine
group compared to chelating dppe or dppm may prevent
cycloaddition at terminal azide around the ruthenium
center. However, the reaction readily undergo with the
analogous complexes of less steric bis phosphine such
as bis dimethylphenylphosphine (PMe2Ph), the work is
served in the range 1268–1295 and 1438–1440 cmꢀ1
,
respectively. The UV–Vis spectra of the complexes 5a
and 5b show absorption band in the region 423–425
nm which is blue shift relative to the starting azido com-
plexes. The complexes are N(2)-bound triazole as evi-
dence from the appearance of a singlet resonance at
1
ca. d 3.62 for the six methoxycarbonyl protons the H
NMR spectra of the complexes (Fig. 1).
It is noteworthy that for the N(1) bound isomer the
spectra would exhibit two resonances for its anisochro-
nous methoxycarbonyl groups. Further the complexes
are N(2) bound isomer was confirmed from the crystal
structure of the representative complexes. The most
1
remarkable feature of the H NMR spectra of the com-
plexes 5b and 6b are the presence of a doublet of triplet
at ca. d 4.93 and 5.26 assigned to the (Ph2P)2CH2
Fig. 1. (a) Proton NMR spectrum of 5b and (b) proton NMR spectrum of 6a in CDCl3.

K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
4229
proton and appearance of unresolved resonance for the
protons of indenyl ligand (H-1,2,3). As expected the
31P{1H} spectra of the indenyl as well as pentamethyl-
cyclopentadienyl complexes display a single resonance
at d 91.16 (5a), 14.56 (3b), 87.32 (4a) and 15.46 (4b)
which is consistent with the chemical equivalence of
both the phosphorous atoms. The 13C{1H} NMR spec-
tra of these complexes exhibit multiplet signals at d
127.59-134.61 for the carbon of the phenyl group.
13C {1H} NMR of the indenyl triazole complexes were
also studied. Kohler [35b] proposed a correlation
between 13C{1H} chemical shift of indenyl ring junc-
tion carbons, C(3a)–(7a) and hapacity of the coordi-
nated ligand. The indenyl carbon resonances and the
calculated parameter Dd(C-3a, 7a) of the complexes
5a and 5b are listed in Table 1. Thus, up field shift
of signals for C(3a)–(7a) relative to indene were indica-
tion of g5-coordination. The calculated values of Dd(C-
3a, 7a) for the complexes 5a and 5b are d ꢀ21.89 and
ꢀ21.94, respectively, which are slightly lower than that
of the starting azido complexes 3a and 3b. These values
are indicative of a slight distortion of the indenyl ring
[35a] and they are consistent with the X-ray diffraction
studies for complexes 5a and 5b.
Fig. 3. Molecular structure of the complex [(g5-C9H7)Ru(dppe)-
(N3C2(CO2Me)2)] (5a) showing 50% probable thermal ellipsoids.
5. Crystal structures
5.1. [(g5-C9H7)Ru(dppe)Cl] (1a), [(g5-C9H7)-
Ru(dppe)(N3C2(CO2Me)2)] (5a) and [(g5-C9H7)-
Ru(dppm)(N3C2(CO2Me)2)] (5b)
The compounds 1a and 5a are crystallizes in P21/c
space group in monoclinic unit cell while that of 5b in
ꢀ
P1 space group in triclinic unit cell. Ortep drawing with
the atoms labeling scheme for the compounds are shown
in Figs. 2–4. The selected bond lengths and angles with
esdꢀs are given in Tables 2–4. The ruthenium atom is
Fig. 4. Molecular structure of the complex [(g5-C9H7)Ru(dppm)-
(N3C2(CO2Me)2)] (5b) showing 50% probable thermal ellipsoids.
coordinated by the indenyl ligand in g5-fashion and dis-
plays the asymmetric coordination generally observed
with this ligand [36]. Thus, ruthenium to ring junction
carbon bond distances is longer than the bond distances
between ruthenium to the adjacent carbon atom of the
five-membered ring. The ruthenium to ring junction
bond distances in the complexes falls within 2.314–
˚
2.3767 A while ruthenium to the rest of the three carbon
of five-membered ring falls in the range of 2.1821–2.2096
˚
A in the complexes 1a, 5a and 5b which are comparable
to that of other indenyl complexes [33,37]. The asym-
metric is explained on the basis of slippage of g5-coordi-
nation towards g3-coordination [38]. Although the
indenyl ligand is g5-bonded to the ruthenium atom,
the structures show slight distortions of five carbons ring
from planarity.
Fig. 2. Molecular structure of the complex [(g5-C9H7)Ru(dppe)Cl]
(1a) showing 50% probable thermal ellipsoids.

4230
K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
The characteristic slippage of the indenyl ring is also
observed with slip-fold (D) values of 0.158(14) (1a),
0.175(2) (5a) and 0.123(13) (5b), which are comparable
to those shown, by indenyl allenylidene complexes [33]
and indenyl azine [37] complexes. These DM–C values
are indicative of slight distortion of g5-indenyl ligand.
The result is consistent with the solution 13C{1H}
NMR data for the complexes (5a) and (5b). For a true
5
˚
g -indenyl ligand D should be ca. 0 A [22a]. As previ-
ously found in other indenyl complexes [22a,34], there
is significant localization of double bond at C(12)–
C(13) and C(10)–C(11) (1a), C(11)–C(12) and C(10)–
C(18) (5a) and C(1)–C(2) and C(3)–C(4) (5b) of the ben-
zo ring of the indenyl moiety. These bond lengths falls in
˚
the range 1.363(4)–1.375(2) A. Both these bond lengths
are significantly shorter than other C–C bond distances
of the benzo ring of which the bond lengths falls in the
˚
range 1.414(4)–1.438(3) A. In contrast, the five-mem-
bered indenyl ring show considerable delocalization of
double bond as evident from the nearly equal C–C bond
distances in the ring, the bond lengths falling within the
range 1.433(2)–1.453(2) (1a), 1.419(4)–1.438(3) (5a) and
Fig. 5. Molecular structure of the complex [(g5-C5Me5)Ru(dppe)-
(N3C2(CO2Me)2)] (6a) showing 50% probable thermal ellipsoids.
˚
1.4254(18)–1.4552(18) A (5b).
The N–N bond distances, viz., N(1)–N(2) and N(1)–
N(3) (Tables 3 and 4) in both the complexes 5a and 5b
are comparatively longer than those of terminal N–N
˚
tion of p-electron in the ring. The Ru–P1 (2.2923(5) A),
˚
˚
Ru–P2 (2.2993 (5) A) and Ru–N (2.1010(16) A) bond
distances are comparable to those of indenyl triazole
complexes 5a and 5b. As in compound 5b the molecule
show the presence of hydrogen bonding between the
hydrogen of phenyl ring C(26)–H(26) and oxygen
O(1); hydrogen of phenyl ring C(43)–H(43) and oxygen
O(3) of the CO2Me groups.
˚
azide bond distances (1.170(8) and 1.146 (10) A) [39]
indicating delocalization of p electron in the heterocyclic
ring. Further there is no significant difference in the Ru–
N1, and bond distances of atoms in the heterocyclic ring
in both the complexes 5a and 5b.The crystal structure of
compound 5b show existence of a number of intra
molecular hydrogen bonding. The bond lengths and
angles of the hydrogen bonds are listed in Table 6.
5.2. [(g5-C5Me5)Ru(dppe)(N3C2(CO2Me)2)] (6a)
6. Conclusions
The present study describe the syntheses of four new
triazole complexes containing g5-indenyl and g5-Cp*
through 1,3-dipolar cycloaddition of dimethylacetylene
dicarboxylate to their corresponding ruthenium azido
complexes. Syntheses of such triazole complexes with
less steric bis phosphine and analogous triazole com-
plexes of arene are under progress.
The compound crystallizes in P21/c space group in a
monoclinic unit cell. An ortep drawing with the atoms
labeling scheme is shown in Fig. 5. Selected bond lengths
and angles are presented in Table 5. The ruthenium
atom is coordinated to C5Me5 ligand in g5-fashion
and displays planarity of the five member Cp* ring as
evident from nearly equal bond distances between ruthe-
nium and carbons of the ring, the bond distances falls
˚
within the range 2.2335(18) to 2.284 (18) A. Further,
7. Supplementary material
there is significant delocalization of p-electron in the
Cp* ring as evident by the nearly equal bond lengths
of C–C atoms in the ring. The bond lengths falls within
Crystallographic data for the structural analysis have
been deposited at the Cambridge Crystallographic Data
Centre (CCDC), CCDC No. 267912 for complex 1a,
CCDC No. 267913 for complex 5a, CCDC No.
267914 for complex 5b and CCDC No. 267915 for com-
plex 6a, respectively. Copies of this information may be
obtained free of charge from The Director, CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44
˚
the range of 1.417(3)–1.448 (3) A. The Ru–N bond dis-
˚
tance in the compound is 2.1010(16) A which is about
˚
˚
0.031 A shorter than a Ru–N3 bond length 2.132(5) A
[40]. This suggests a stronger bond for Ru–N bond of
triazole compound as compared to Ru–N3 bond. Inter-
estingly, the five member heterocyclic triazole ring has
equal bond lengths suggesting a considerable delocaliza-

K.S. Singh et al. / Journal of Organometallic Chemistry 690 (2005) 4222–4231
4231
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Acknowledgements
We thank Sophisticated Instruments Facility (SIF),
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