Mono and dinuclear complexes of half-sandwich platinum group metals (Ru, Rh and Ir) bearing a flexible pyridyl-thiazole multidentate donor ligand

Article abstract of DOI:10.1016/j.jorganchem.2009.10.007

The mononuclear cationic complexes [(η⁶-C₆H₆)RuCl(L)]⁺ (1), [(η⁶-p-ⁱPrC₆H₄Me)RuCl(L)]⁺ (2), [(η⁵-C₅H₅)Ru(PPh₃)(L)]⁺ (3), [(η⁵-C₅Me₅)Ru(PPh₃)(L)]⁺ (4), [(η⁵-C₅Me₅)RhCl(L)]⁺ (5), [(η⁵-C₅Me₅)IrCl(L)]⁺ (6) as well as the dinuclear dicationic complexes [{(η⁶-C₆H₆)RuCl}₂(L)]²⁺ (7), [{(η⁶-p-ⁱPrC₆H₄Me)RuCl}₂(L)]²⁺ (8), [{(η⁵-C₅H₅)Ru(PPh₃)}2(L)]²⁺ (9), [{(η⁵-C₅Me₅)Ru(PPh₃)}₂(L)]²⁺ (10), [{(η⁵-C₅Me₅)RhCl}₂(L)]²⁺ (11) and [{(η⁵-C₅Me₅)IrCl}₂(L)]²⁺ (12) have been synthesized from 4,4′-bis(2-pyridyl-4-thiazole) (L) and the corresponding complexes [(η⁶-C₆H₆)Ru(μ-Cl)Cl]₂, [(η⁶-p-ⁱPrC₆H₄Me)Ru(μ-Cl)Cl]₂, [(η⁵-C₅H₅)Ru(PPh₃)₂Cl)], [(η⁵-C₅Me₅)Ru(PPh₃)₂Cl], [(η⁵-C₅Me₅)Rh(μ-Cl)Cl]₂ and [(η⁵-C₅Me₅)Ir(μ-Cl)Cl]₂, respectively. All complexes were isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry and UV-vis spectroscopy. The X-ray crystal structure analyses of [3]PF₆, [5]PF₆, [8](PF₆)₂ and [12](PF₆)₂ reveal a typical piano-stool geometry around the metal centers with a five-membered metallo-cycle in which 4,4′-bis(2-pyridyl-4-thiazole) acts as a N,N′-chelating ligand.

Full text of DOI:10.1016/j.jorganchem.2009.10.007

Journal of Organometallic Chemistry 695 (2010) 226–234
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Mono and dinuclear complexes of half-sandwich platinum group metals
(Ru, Rh and Ir) bearing a flexible pyridyl-thiazole multidentate donor ligand
Kota Thirumala Prasad a, Bruno Therrien b, Kollipara Mohan Rao a,
*
a Department of Chemistry, North Eastern Hill University, Shillong 793 022, India
b Service Analytique Facultaire, University of Neuchatel, Case Postale 158, CH-2009 Neuchatel, Switzerland
a r t i c l e i n f o
a b s t r a c t
The mononuclear cationic complexes [(g g -
6-C6H6)RuCl(L)]+ (1), [( 6-p-iPrC6H4Me)RuCl(L)]+ (2), [(g5
Article history:
C5H5)Ru(PPh3)(L)]+ (3), [(
g
5-C5Me5)Ru(PPh3)(L)]+ (4), [(
g
5-C5Me5)RhCl(L)]+ (5), [(
g
5-C5Me5)IrCl(L)]+ (6)
6-p-iPrC6H4Me)RuCl}2(L)]2+
5-C5Me5)RhCl}2(L)]2+ (11) and
Received 31 August 2009
Received in revised form 29 September
2009
Accepted 1 October 2009
Available online 12 October 2009
as well as the dinuclear dicationic complexes [{(
(8), [{(
5-C5H5)Ru(PPh3)}2(L)]2+ (9), [{(
[{(
5-C5Me5)IrCl}2(L)]2+ (12) have been synthesized from 4,40-bis(2-pyridyl-4-thiazole) (L) and the corre-
sponding complexes [( -Cl)Cl]2, [( -Cl)Cl]2, [(
6-C6H6)Ru( 6-p-iPrC6H4Me)Ru( 5-C5H5)Ru(PPh3)2Cl)],
[( -Cl)Cl]2 and [( -Cl)Cl]2, respectively. All com-
5-C5Me5)Ru(PPh3)2Cl], [( 5-C5Me5)Rh( 5-C5Me5)Ir(
g
6-C6H6)RuCl}2(L)]2+ (7), [{(
g
g
g
5-C5Me5)Ru(PPh3)}2(L)]2+ (10), [{(
g
g
g
l
g
l
g
g
g
l
g
l
Keywords:
plexes were isolated as hexafluorophosphate salts and characterized by IR, NMR, mass spectrometry
and UV–vis spectroscopy. The X-ray crystal structure analyses of [3]PF6, [5]PF6, [8](PF6)2 and [12](PF6)2
reveal a typical piano-stool geometry around the metal centers with a five-membered metallo-cycle in
which 4,40-bis(2-pyridyl-4-thiazole) acts as a N,N0-chelating ligand.
Arene-ligands
Mono and dinuclear complexes
Pyridylthiazoles
Ruthenium
Rhodium
Iridium
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
gand to bridge two metal centers for the formation of dinuclear
complexes. Inclusion of the five-membered thiazolyl rings in the
Metal complexes based on polypyridyl ligands constitute ver-
satile components for the construction of multifunctional supra-
molecular systems in molecular photonics and molecular
electronics, sensors, photo-catalysis, solar energy conversion, arti-
ficial photosynthesis, non-linear optics, and electrochemo-lumi-
nescence amongst others [1–15]. Despite the diversity of these
potential applications, relatively little is known about how the
properties of electron transfer between a single donor and accep-
tor is influenced by their inclusion into larger supramolecular
assemblies. In this regard, ruthenium complexes bridged by mul-
tiple nitrogen donor polypyridyl ligands have received consider-
able recent attention because of their possible applications in
homogeneous catalysis [16–21], as multi electron storage system
[22–24], in the designing of new materials [25–28] and in photo-
physical and photochemical molecular devices [29–33]. One of
the simplest linker used in assembling metals in such arrays is
4,40-bis(2-pyridyl-4-thiazole) (L). This molecule has been princi-
pally explored with Co, Cu and Zn transition metal atoms and
has been shown to generate helical structures [34–36]. Besides
these helical structures, this molecule acts as a bis-chelating li-
backbone results in a more pronounced partitioning of the ligand
into distinct bidentate domains than is the case with linear poly-
pyridines. This facilitates the formation of mononuclear and dinu-
clear systems. The former one has the potential to behave as
metallo-ligands in the development of homo/hetero bimetallic
systems [37–40].
Arene ruthenium complexes play an important role in organo-
metallic chemistry. Reactions of the chloro bridged arene ruthe-
nium complexes [{(g l-Cl)}2] with Lewis bases and
6-arene)RuCl(
a variety of different ligands have been extensively studied. Re-
cently, we have reported a series of mononuclear arene ruthenium
complexes of the type [(
complexes [{(
6-arene)RuCl}2(bpp)]2+ (arene = C6H6, p-iPrC6H4Me;
g
6-arene)RuCl(H-bpp)]+ and the dinuclear
g
bpp = 3,3-bis(2-pyridyl)pyrazole) [41]. However, there are no re-
ports dealing with half-sandwich ruthenium/rhodium/iridium
complexes with ligands consisting of pyridyl units connected to
thiazolyl ring backbone.
In the present contribution, we have synthesized new mononu-
clear and dinuclear complexes with arene ruthenium, rhodium and
iridium complexes with polypyridyl ligand as thiazolyl rings back-
bone. All these new complexes were characterized by elemental
analyses, 1H NMR, UV–vis and mass spectrometry as well as
X-ray crystallographic analyses for some representatives.
* Corresponding author. Tel.: +91 364 272 2620; fax: +91 364 272 1010.
E-mail address: mohanrao59@gmail.com (K.M. Rao).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.10.007

K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
227
CH(CH3)2); IR (cm-1): 1604(m), 1449(s), 1437(s), 843(s), 783(s),
558(s); ESI-MS: 593.1 [M+], 458.1 [MꢁCl]; UV–vis {acetonitrile,
kmax nm
(e
10ꢁ5 Mꢁ1 cmꢁ1)}: 336 (0.20); Anal. Calc. for
C26H24ClF6N4PRuS2 (738.1): C, 42.31; H, 3.28; N, 7.59. Found: C,
42.27; H, 3.31; N, 7.57%.
S
N
N
N
N
2.1.3. [(
g
5-C5H5)Ru(L)(PPh3)]PF6 ([3]PF6)
5-C5H5)Ru(PPh3)2Cl] (100 mg, 0.13 mmol), L
S
A mixture of [(
g
[4,40-bis(2-pyridyl-4-thiazole)] (48 mg, 0.15 mmol) and potassium
hexafluorophosphate (26 mg, 0.15 mmol) was suspended in meth-
anol (35 ml) and refluxed for 12 h. Then, the insoluble materials
were filtered through celite and the filtrate was evaporated to dry-
ness. The residue dissolved in dichloromethane and filtered
through celite to remove excess potassium hexafluorophosphate
and ammonium chloride. The filtrate was reduced to 2 ml on rotary
evaporator and excess hexane was added to induce dark red color
precipitate. The precipitate was separated by centrifugation,
washed with diethylether (3 ꢀ 10 ml) and then dried in vacuo.
Yield 70 mg (56%). 1H NMR (400 MHz, CD3CN d = 9.07 (d, 1H,
3J = 4.40 Hz), 9.01 (s, 1H), 8.66 (d, 1H, 3J = 7.60 Hz), 8.16 (s, 1H),
7.82 (t, 1H, 3J = 8.00 Hz), 7.60 (t, 1H, 3J = 6.40 Hz), 7.51 (t, 2H,
3J = 7.20 Hz), 7.46 (d, 1H, 3J = 6.42 Hz), 7.28 (d, 1H, 3J = 4.28 Hz),
7.19–7.10 (m, 15H), 4.58 (s, 5H, C5H5); 31P {1H} (CD3CN)
d = 49.34 ppm; IR (cm-1): 1604(m), 1454(s), 1438(s), 844(s),
785(s), 559(s); ESI-MS: 750.8 [M+]; UV–vis {acetonitrile, kmax nm
[4,4'-bis(2-pyridyl-4-thiazole)] (L)
2. Experimental
All reagents were purchased either from Aldrich or Fluka and
used as received. All the experiments were performed under nor-
mal conditions. The dinuclear complexes [(
[( -Cl)Cl]2 [42–44], and [(
6-p-iPrC6H4Me)Ru(
Cl)Cl]2 (M = Rh and Ir) [45–47], the mononuclear complexes [(g5
C5H5)Ru(PPh3)2Cl] [48] and [(
g
6-C6H6)Ru(
5-C5Me5)M(
l-Cl)Cl]2,
g
l
g
l-
-
g
5-C5Me5)Ru(PPh3)2Cl] [49] as well
as 4,40-bis(2-pyridyl-4-thiazole) [34] were prepared according to
literature methods. NMR spectra were recorded on an AMX-
400 MHz spectrometer. Infrared spectra were recorded as KBr pel-
lets on a Perkin-Elmer 983 spectrophotometer. Elemental analyses
were performed on a Perkin-Elmer-2400 CHN/S analyzer. Mass
spectra were obtained from ZQ mass spectrometer by ESI method.
Absorption spectra were obtained at room temperature using a
Perkin–Elmer Lambda 25 UV/visible spectrophotometer.
(e
10ꢁ5 Mꢁ1 cmꢁ1)}: 341 (0.15); Anal. Calc. for C39H30F6N4P2RuS2
(895.82): C, 52.29; H, 3.38; N 6.25. Found: C, 52.11; H, 3.29; N,
6.17%.
2.1.4. [(
Compound [4]PF6 was prepared by the same procedure as de-
g
5-C5Me5)Ru(L)(PPh3)]PF6 ([4]PF6)
2.1. Syntheses of the mononuclear complexes [1]PF6–[6]PF6
scribed above for [5]PF6 using [(g
5-C5Me5)Ru(PPh3)2Cl] (100 mg,
0.12 mmol), L [4,40-bis(2-pyridyl-4-thiazole)] (44 mg, 0.13 mmol)
and potassium hexafluorophosphate (26 mg, 0.15 mmol).
2.1.1. [(
g
6-C6H6)Ru(L)Cl]PF6 ([1]PF6)
6-C6H6)Ru(
-Cl)Cl]2 (50 mg, 0.1 mmol) and L
A mixture of [(
g
l
Yield 82 mg (79%). 1H NMR (400 MHz, CD3CN) d = 9.17 (d, 1H,
3J = 5.60 Hz), 9.01 (s, 1H), 8.76 (d, 1H, 3J = 4.48 Hz), 8.30 (s, 1H),
7.86 (t, 1H, 3J = 7.60 Hz), 7.72 (t, 1H, 3J = 6.40 Hz), 7.61 (t, 2H,
3J = 6.00 Hz), 7.49 (d, 1H, 3J = 4.20 Hz), 7.22 (d, 1H, 3J = 3.28 Hz),
7.29–7.10 (m, 15H), 2.01 (s, 15H, C5Me5); 31P {1H} (CD3CN)
d = 51.54 ppm; IR (cmꢁ1): 1624(m), 1458(s), 1437(s), 843(s),
778(s), 557(s); ESI-MS: 820.1 [M+]; UV–vis {acetonitrile, kmax nm
[4,40-bis(2-pyridyl-4-thiazole)] (66 mg, 0.21 mmol) was suspended
in methanol (20 ml) and stirred at room temperature for 2 h. Then,
the insoluble materials were filtered through celite and potassium
hexafluorophosphate (48 mg, 0.25 mmol) was added to the filtrate.
After stirring for 4 h at room temperature a precipitate was ob-
served. The precipitate was filtered, washed with methanol and
diethylether (3 ꢀ 10 ml) and dried in vacuo.
(e
10ꢁ5 Mꢁ1 cmꢁ1)}: 334 (0.55); Anal. Calc. for C44H40F6N4P2RuS2
(965.95): C, 54.71; H, 4.17; N, 5.80. Found: C, 54.59; H, 4.08; N,
5.68%.
Yield 85 mg (62%). 1H NMR (400 MHz, CD3CN) d = 9.46 (d, 1H,
3J = 4.76 Hz), 9.15 (s, 1H, tz-H), 8.67 (d, 1H, 3J = 3.20 Hz), 8.66 (s,
1H, tz-H), 8.36–8.08 (dd, 3H), 8.13 (t, 1H, 3J = 3.32 Hz), 7.63 (t,
2H, 3J = 2.54 Hz), 5.95 (s, 6H, C6H6); IR (cmꢁ1): 1614 (m), 1454
(s), 1437 (s), 844 (s), 788 (s), 558 (s); ESI-MS: 537.1 [M+], 492.2
2.1.5. [(
g
5-C5Me5)Rh(L)Cl]PF6 ([5]PF6)
5-C5Me5)Rh(
-Cl)Cl]2 (50 mg, 0.08 mmol) and L
[MꢁCl]; UV–vis {acetonitrile, kmax nm (
e
10ꢁ5 Mꢁ1 cmꢁ1)}: 338
A mixture of [(
g
l
(0.19); Anal. Calc. for C22H16N4S2RuClPF6 (682.01): C, 38.74; H,
[4,40-bis(2-pyridyl-4-thiazole)] (55 mg, 0.17 mmol) was suspended
in methanol (20 ml) and refluxed for 4 h. Then, the insoluble mate-
rials were passed through celite and potassium hexafluorophos-
phate (36 mg, 0.22 mmol) was added to the filtrate. After
refluxing for an hour a precipitate was observed. The precipitate
was filtered, washed with methanol and diethylether (3 ꢀ 10 ml)
and dried in vacuo.
2.36; N 8.21. Found: C, 38.53; H, 2.47; N, 8.18%.
2.1.2. [(
Compound [2]PF6 was prepared by the same procedure as de-
scribed above for [1]PF6 using [( -Cl)Cl]2
6-p-iPrC6H4Me)Ru(
(60 mg, 0.09 mmol),
[4,40-bis(2-pyridyl-4-thiazole)] (65 mg,
g
6-p-iPrC6H4Me)Ru(L)Cl]PF6 ([2]PF6)
g
l
L
0.20 mmol) and potassium hexafluorophosphate (36 mg,
0.23 mmol).
Yield 90 mg (78%). 1H NMR (400 MHz, CD3CN) d = 8.95 (d, 1H,
3J = 5.28 Hz), 8.71 (s, 1H), 8.66 (d, 1H, 3J = 4.40 Hz), 8.30 (s, 1H),
7.86 (t, 1H, 3J = 7.40 Hz), 7.62 (t, 1H, 3J = 6.80 Hz), 7.52 (t, 2H,
3J = 6.40 Hz), 7.32 (d, 1H, 3J = 6.44 Hz), 7.22 (d, 1H, 3J = 6.00 Hz),
2.11 (s, 15H, C5Me5); IR (cmꢁ1): 1603(m), 1458(s), 1437(s),
845(s), 785(s), 558(s); ESI-MS: 560.3 [M+], 525.1 [MꢁCl]; UV–vis
Yield 113 mg (78%). 1H NMR (400 MHz, CD3CN) d = 9.30 (d, 1H,
3J = 5.66 Hz), 9.15 (s, 1H), 9.06 (s, 1H), 8.67 (d, 1H, 3J = 3.72 Hz),
8.13 (t, 2H, 3J = 7.6 Hz), 8.01 (d, 2H, 3J = 2.72 Hz), 7.79 (t, 2H,
3J = 6.40 Hz), 5.59 (d, 1H, 3J = 6.00 Hz, Arp-cy), 5.52 (d, 1H,
3J = 6.00 Hz, Arp-cy), 5.46 (d, 1H, 3J = 6.00 Hz, Arp-cy), 5.39 (d, 1H,
{acetonitrile, kmax nm (e
10ꢁ5 Mꢁ1 cmꢁ1)}: 333 (0.72); Anal. Calc.
3J = 5.60 Hz, Arp-cy) 2.70 (sept, 1H, CH(CH3)2), 2.33 (s, 3H, Arp-cy
-
for C26H25F6N4PRhS2 (705.5): C, 44.26; H, 3.57; N 7.94. Found: C,
44.13; H, 3.43; N, 7.86%.
Me), 1.71 (d, 3H, 3J = 6.20 Hz, CH(CH3)2), 1.69 (d, 3H, 3J = 6.80 Hz,

228
K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
2.1.6. [(
g
5-C5Me5)Ir(L)Cl]PF6 ([6]PF6)
Yield 81 mg (80%). 1H NMR (400 MHz, CD3CN) d = 9.29 (d, 2H,
3J = 5.60 Hz), 8.67 (s, 2H, tz-H), 8.26 (d, 2H, 3J = 4.40 Hz), 8.06 (t,
2H, 3J = 7.20 Hz), 7.57 (m, 2H), 7.29–7.02 (m, 30H), 4.86 (s, 10H,
C5H5); 31P {1H} (CD3CN) d = 49.28; IR (cmꢁ1): 1624(m)ꢁ, 1458(s),
1437(s), 843(s), 778(s), 557(s); ESI-MS: 1179 1 [M2++PF6 ]2+; UV–
Compound [6]PF6 was prepared by the same procedure as de-
scribed above for [5]PF6 using [(g l-Cl)Cl]2 (66 mg,
5-C5Me5)Ir(
0.08 mmol), L [4,40-bis(2-pyridyl-4-thiazole)] (57 mg, 0.18 mmol)
and potassium hexafluorophosphate (46 mg, 0.25 mmol).
Yield 79 mg (60%). 1H NMR (400 MHz, CD3CN) d = 9.01 (d, 1H,
3J = 5.60 Hz), 8.91 (s, 1H), 8.76 (d, 1H, 3J = 6.40 Hz), 8.35 (s, 1H),
7.89 (t, 1H, 3J = 7.00 Hz), 7.72 (t, 1H, 3J = 6.80 Hz), 7.52 (t, 2H,
3J = 6.00 Hz), 7.42 (d, 1H, 3J = 5.60 Hz), 7.28 (d, 1H, 3J = 6.48 Hz),
1.87 (s, 15H, C5Me5); IR (cmꢁ1): 1606(m), 1454(s), 1437(s),
844(s), 785(s), 558(s); ESI-MS: 649.8 [M+], 614.6 [MꢁCl]; UV–vis
vis {acetonitrile, kmax nm (e
10ꢁ5 Mꢁ1 cmꢁ1)}: 314 (0.72) and 356
(0.32); Anal. Calc. for C62H50F12N4P4Ru2S2 (1469.2): C, 50.68; H,
3.43; N 3.81. Found: C, 50.56; H, 3.57; N, 3.77%.
2.2.4. [{(
Compound [10](PF6)2 was prepared by the same procedure as de-
g l-L)](PF6)2 ([10](PF6)2)
5-C5Me5)Ru(PPh3)}2(
{acetonitrile, kmax nm (
for C26H25F6IrN4PS2 (794.8): C, 39.29; H, 3.17; N 7.05. Found: C,
39.13; H, 3.21; N, 6.99%.
e
10ꢁ5 Mꢁ1 cmꢁ1)}: 336 (0.74); Anal. Calc.
scribed above for [9](PF6)2, using [(g
5-C5Me5)Ru(PPh3)2Cl] (100 mg,
0.12 mmol), L [4,40-bis(2-pyridyl-4-thiazole)] (20 mg, 0.06 mmol)
and potassium hexafluorophosphate (23 mg, 0.12 mmol).
Yield 71 mg (69%). 1H NMR (400 MHz, CD3CN) d = 9.32 (d, 2H,
3J = 5.20 Hz), 8.78 (s, 2H, tz-H), 8.26 (d, 2H, 3J = 4.40 Hz), 8.11 (t,
2H, 3J = 7.80 Hz), 7.57 (t, 2H, 3J = 6.40 Hz), 7.29–7.08 (m, 30H),
1.97 (s, 30H); 31P {1H} (CD3CN) d = 51.33; IR (cmꢁ1): 1604(m),
1454(s),ꢁ 1438(s), 844(s), 785(s), 559(s); ESI-MS: 1319.8
2.2. Syntheses of the dinuclear complexes [7](PF6)2 to [12](PF6)2
2.2.1. [{(
g
6-C6H6)RuCl}2(
6-C6H6)Ru(
l
-L)](PF6)2 ([7](PF6)2)
A mixture of [(
g
l
-Cl)Cl]2 (83 mg, 0.16 mmol) and L
[M2++PF6 ]2+; UV–vis {acetonitrile, kmax nm ( 10ꢁ5 Mꢁ1 cmꢁ1)}:
e
[4,40-bis(2-pyridyl-4-thiazole)] (53 mg, 0.16 mmol) was suspended
in methanol (20 ml) and stirred at room temperature for 6 h. Then,
potassium hexafluorophosphate (46 mg, 0.25 mmol) was added to
the reaction mixture and further stirred for 3 h. The precipitate was
filtered, washed with methanol and diethylether (3 ꢀ 10 ml) and
dried in vacuo.
310 (0.81) and 358 (0.33); Anal. Calc. for C72H70F12N4P4Ru2S2
(1609.5): C, 53.73; H, 4.38; N, 3.48. Found: C, 53.61; H, 4.27; N,
3.39%.
2.2.5. [{(
g
5-C5Me5)RhCl}2(
5-C5Me5)Rh(
l
-L)](PF6)2 ([11](PF6)2)
A mixture of [(
g
l-Cl)Cl]2 (75 mg, 0.12 mmol) and L
Yield 110 mg (60%). 1H NMR (400 MHz, CD3CN) d = 9.38 (d, 2H,
3J = 4.80 Hz), 8.67 (s, 2H, tz-H), 8.22 (d, 2H, 3J = 8.40 Hz), 8.13 (t, 2H,
3J = 7.20 Hz), 7.43–7.51 (m, 2H), 6.01 (s, 6H, C6H6), 5.99 (s, 6H,
C6H6); IR (cmꢁ1): 1604(m), 1449(s), 1437(s), 843(s), 783(s),
558(s); ESI-MS: 891.8 [M2++PF6ꢁ]+; UV–vis {acetonitrile, kmax nm
[4,40-bis(2-pyridyl-4-thiazole)] (39 mg, 0.1 mmol) was suspended
in methanol (20 ml) and refluxed for 4 h. Then, potassium hexa-
fluorophosphate (23 mg, 0.13 mmol) was added to the reaction
mixture and further refluxed for an hour. During this time was pre-
cipitate was observed. The precipitate was filtered, washed with
methanol and diethylether (3 ꢀ 10 ml) and dried in vacuo.
(e
10ꢁ5 Mꢁ1 cmꢁ1)}: 311 (0.35) and 356 (0.31); Anal. Calc. for
C28H22Cl2F12N4P2Ru2S2 (1041.6): C, 32.29; H, 2.13; N 5.38. Found:
C, 32.15; H, 2.05; N, 5.28%.
Yield 118 mg (89%). 1H NMR (400 MHz, CD3CN) d = 9.11 (d, 2H,
3J = 5.20 Hz), 8.72 (s, 2H, tz-H), 8.21 (d, 2H, 3J = 5.60 Hz), 8.11 (t, 1H,
3J = 7.20 Hz), 7.96 (t, 1H, 3J = 7.24 Hz), 7.57 (t, 2H, 3J = 6.40 Hz), 2.15
(s, 30H, C5Me5); IR (cmꢁ1): 1606(m), 1454(s), 1437(s), 844(s),
785(s), 558(s); ESI-MS: 943.6 [M2++PF6ꢁ]+; UV–vis {acetonitrile,
2.2.2. [{(
Compound [8](PF6)2 was prepared by the same procedure as de-
scribed above for [7](PF6)2 using [( -Cl)Cl]2
6-p-iPrC6H4Me)Ru(
(63 mg, 0.1 mmol),
[4,40-bis(2-pyridyl-4-thiazole)] (33 mg,
potassium hexafluorophosphate (23 mg,
g l-L)](PF6)2 ([8](PF6)2)
6-p-iPrC6H4Me)RuCl}2(
g
l
kmax nm (e
10ꢁ5 Mꢁ1 cmꢁ1)}: 312 (0.78) and 356 (0.33); Anal. Calc.
L
for C36H40F12N4P2Rh2S2 (1088.6): C, 39.72; H, 3.70; N, 5.15. Found:
C, 39.53; H, 3.67; N, 5.07%.
0.1 mmol)
and
0.12 mmol).
Yield 101 mg (85%). 1H NMR (400 MHz, CD3CN) d = 9.37 (d, 2H,
3J = 5.20 Hz), 8.67 (s, 2H, tz-H), 8.26 (d, 2H, 3J = 5.60 Hz), 8.06 (t, 2H,
3J = 7.00 Hz), 7.57 (t, 2H, 3J = 6.80 Hz), 5.86 (d, 2H, 3J = 6.00 Hz,
Arp-cy), 5.56 (d, 2H, 3J = 5.60 Hz, Arp-cy), 5.47 (d, 2H, 3J = 6.00 Hz,
Arp-cy), 5.38 (d, 2H, 3J = 6.40 Hz Arp-cy), 2.42 (sept, 2H, CH(CH3)2),
2.05 (s, 6H, Arp-cy-Me), 1.38 (d, 3H, CH(CH3)2); 1.17 (d, 3H,
CH(CH3)2), 1.08 (d, 3H, CH(CH3)2), 0.98 (d, 3H, CH(CH3)2); IR
(cmꢁ1): 1614(m), 1454(s), 1437(s), 844(s), 788(s), 558(s); ESI-MS:
2.2.6. [{(
g
5-C5Me5)IrCl}2(
l
-L)](PF6)2 ([12](PF6)2)
5-C5Me5)Ir(
l-Cl)Cl]2 (72 mg,
Compound [12](PF6)2 was prepared by the same procedure as de-
scribed above for [11](PF6)2 using [(
g
0.09 mmol), L [4,40-bis(2-pyridyl-4-thiazole)] (29 mg, 0.09 mmol)
and potassium hexafluorophosphate (23 mg, 0.12 mmol).
Yield 91 mg (79%). 1H NMR (400 MHz, CD3CN) d = 9.44 (d, 2H,
3J = 5.60 Hz), 8.90 (s, 2H, tz-H), 8.28 (d, 2H, 3J = 8.00 Hz), 8.15 (t,
1H, 3J = 7.20 Hz), 7.98 (t, 1H, 3J = 6.80 Hz), 7.57 (t, 2H,
3J = 6.44 Hz), 1.54 (s, 30H, C5Me5); IR (cmꢁ1): 1603(m),ꢁ1458(s),
1437(s), 845(s), 785(s), 558(s); ESI-MS: 1122.5 [M2++PF6 ]+; UV–
1008.2
[M2++PFꢁ6 ]+;
UV–vis
{acetonitrile,
kmax
nm
(e
10ꢁ5 Mꢁ1 cmꢁ1)}: 312 (0.56) and 355 (0.35); Anal. Calc. for
C36H38Cl2F12N4P2Ru2S2 (1153.7): C, 37.47; H, 3.32; N 4.86. Found:
vis {acetonitrile, kmax nm (e
10ꢁ5 Mꢁ1 cmꢁ1)}: 310 (0.74) and 358
C, 37.33; H, 3.27; N, 4.77%.
(0.32); Anal. Calc. for C36H40F12Ir2N4P2S2 (1267.2): C, 34.12; H,
3.18; N, 4.42. Found: C, 34.02; H, 3.09; N, 4.37%.
2.2.3. [{(
g
5-C5H5)Ru(PPh3)}2(
5-C5H5)Ru(PPh3)2Cl] (100 mg, 0.13 mmol), L
l-L)](PF6)2 ([9](PF6)2)
A mixture of [(
g
2.3. X-ray crystallography
[4,40-bis(2-pyridyl-4-thiazole)] (22 mg, 0.068 mmol) and ammo-
nium hexafluorophosphate (46 mg, 0.28 mmol) was suspended in
methanol (35 ml) and refluxed for 12 h. Then, the insoluble mate-
rials were filtered through celite and filtrate was evaporated to
dryness. The residue was dissolved in dichloromethane and filtered
through celite to remove ammonium chloride and excess ammo-
nium hexafluorophosphate. The filtrate was reduced to 2 ml and
excess hexane was added to induce dark red color precipitate.
The precipitate was separated by centrifugation, washed with
diethylether (3 ꢀ 10 ml) and dried in vacuo.
Crystals of complexes [3]PF6ꢂ(CH3)2CO, [5]PF6ꢂ(CH3)2CO,
[8](PF6)2ꢂCH3CN and [12](PF6)2ꢂCH2Cl2 were mounted on a Stoe Im-
age Plate Diffraction system equipped with a / circle goniometer,
using Mo Ka graphite monochromated radiation (k = 0.71073 Å)
with / range 0–200°. The structures were solved by direct methods
using the program SHELXS-97 [50]. Refinement and all further calcu-
lations were carried out using SHELXL-97 [51]. The H-atoms were in-
cluded in calculated positions and treated as riding atoms using
the SHELXL default parameters. The non-H atoms were refined

K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
229
Table 1
Crystallographic and structure refinement parameters for complexes [3]PF6ꢂ(CH3)2CO, [5]PF6ꢂ(CH3)2CO, [8](PF6)2ꢂCH3CN and [12](PF6)2ꢂCH2Cl2.
[3]PF6ꢂ(CH3)2CO
[5]PF6ꢂ(CH3)2CO
[8](PF6)2ꢂCH3CN
[12](PF6)2ꢂCH2Cl2
Chemical formula
Formula weight
Crystal system
Space group
Crystal color and shape
Crystal size
a (Å)
C42H36F6N4OP2RuS2
953.88
C29H31ClF6N4OPRhS2
799.03
C38H41Cl2F12N5P2Ru2S2
1194.86
C37H42Cl4F12Ir2N4P2S2
1423.01
Triclinic
Triclinic
Triclinic
Orthorhombic
P21212 (no. 18)
Orange rod
0.27 ꢀ 0.19 ꢀ 0.16
11.809(2)
25.787(5)
7.588(2)
90
90
90
2310.7(9)
2
ꢀ
ꢀ
ꢀ
P1 (no. 2)
P1 (no. 2)
P1 (no. 2)
Orange block
0.23 ꢀ 0.17 ꢀ 0.16
9.995(1)
13.505(2)
15.294(2)
98.163(17)
91.233(16)
96.897(15)
2027.2(5)
2
Orange rod
0.28 ꢀ 0.23 ꢀ 0.18
8.588(2)
11.802(2)
16.802(3)
70.68(3)
89.32(3)
80.92(3)
1585.4(5)
2
Orange block
0.35 ꢀ 0.26 ꢀ 0.21
12.0713(12)
13.3379(13)
15.1076(16)
67.863(11)
80.764(12)
88.372(12)
2222.5(4)
2
b (Å)
c (Å)
a
(°)
b (o)
c
(°)
V (Å3)
Z
T (K)
173(2)
1.563
0.636
2.18 < h < 26.21
7491
173(2)
1.674
0.872
2.40 < h < 26.10
5827
173(2)
1.785
1.053
2.07 < h < 26.13
8164
173(2)
2.045
6.227
2.34 < h < 26.03
4541
Dcalc (g cm-3
)
l
(mmꢁ1
)
Scan range (o)
Unique reflections
Reflections used [I > 2
Rint
r
(I)]
1896
0.1776
3376
0.0484
5144
0.0441
2982
0.2056
Flack parameter
–
–
–
0.38(3)
Final R indices [I > 2
R indices (all data)
Goodness-of-fit
r
(I)]a
0.0479, wR2 0.0895
0.2140, wR2 0.1243
0.531
0.428, ꢁ0.829
0.0348, wR2 0.0620
0.0797, wR2 0.0685
0.752
0.654, ꢁ1.051
0.0335, wR2 0.0675
0.0669, wR2 0.0750
0.831
0.757, ꢁ0.899
0.0922, wR2 0.2146
0.1300, wR2 0.2394
0.986
4.272, ꢁ3.043
Maximum, minimum
D
q
(e Åꢁ3
)
Structures were refined on F2o: wR2 = [
R
[w(F2o ꢁ F2c )2]/
R R
w(F2o)2]1/2, where wꢁ1 = [ (Fo2) + (aP)2 + bP] and P = [max(Fo2, 0) + 2F2c ]/3.
a
anisotropically, using weighted full-matrix least-square on F2. In
[12](PF6)2ꢂ ꢂ ꢂCH2Cl2 the max./min. residual density 4.510/
ꢁ3.120 e Åꢁ3 are located at less than 1 Å from the iridium atoms.
Crystallographic details are summarized in Table 1 and selected
bond lengths and angles are presented in Table 2. Figs. 1–4 of com-
plexes [3]PF6ꢂ(CH3)2CO, [5]PF6ꢂ(CH3)2CO, [8](PF6)2ꢂCH3CN and
[12](PF6)2ꢂCH2Cl2 were drawn with ORTEP-32 [52], respectively.
iridium complexes having 4,40-bis(2-pyridyl-4-thiazole) (L) ligand
viz., [(
[2]PF6,
g
6-C6H6)RuCl(L)]PF6 [1]PF6, [(
[(
5-C5H5)Ru(PPh3)(L)]PF6
5-C5Me5)RhCl(L)]PF6 [5]PF6 and [(g5
-
g
6-p-iPrC6H4Me)RuCl(L)]PF6
g
[3]PF6, [(
g
5-C5Me5)Ru
(PPh3)(L)]PF6 [4]PF6, [(
g
C5Me5)IrCl(L)]PF6 [6]PF6 (Scheme 1) have been prepared by the
reaction of arene or cyclopentadienyl or pentamethylcyclopenta-
dienyl complexes [(
p-iPrC6H4Me), [( 5-Cp)Ru(PPh3)2Cl] (Cp = C5H5 and C5Me5) and
[( -Cl)Cl]2 (M = Rh and Ir) with appropriate equiva-
5-C5Me5)M(
g l-Cl)Cl]2 (arene = C6H6 and
6-arene)Ru(
g
g
l
3. Results and discussion
lents of ligand L [4,40-bis(2-pyridyl-4-thiazole)] in methanol. These
complexes are isolated as hexafluorophosphate salts and com-
plexes [1]PF6 to [6]PF6 are orange-red, resulting as non-hygro-
scopic, air-stable, shiny crystalline solids. They are sparingly
soluble in methanol, dichloromethane and chloroform, but well
soluble in acetone and acetonitrile. All these complexes were fully
characterized by IR, 1H NMR and electronic spectroscopy. In addi-
tion to these complexes 3 and 4 were characterized by 31P NMR
also. Analytical data of the complexes conformed well to their
respective formulations. Further information about composition
of the complexes has also been obtained from mass spectrometry.
Infrared spectra of the ligand L [4,40-bis(2-pyridyl-4-thiazole)]
display an absorption bands at 1452 and 1437 cmꢁ1 assignable to
the stretching frequencies of C@N and C@S bands, respectively,
consistent with the fact that C@N and C@S stretching frequencies
of thiazole appear in the range 1452 and 1437 cmꢁ1, respectively
[53]. Upon coordination with metal atoms the same bands ap-
3.1. Synthesis of the mononuclear complexes [1]PF6 to [6]PF6 as
hexafluorophosphate salts
The mononuclear cationic arene ruthenium as well as cyclopen-
tadienyl and pentamethylcyclopentadienyl ruthenium, rhodium or
Table 2
Selected bond lengths (Å) and angles (°) for complexes [3]PF6, [5]PF6, [8](PF6)2 and
[12](PF6)2.
[3]PF6
[5]PF6
[8](PF6)2
[12](PF6)2
Distances (Å)
M–N1
M–N2
M–N3
M–N4
2.067(8)
2.105(7)
–
–
2.100(3)
2.146(3)
–
–
2.094(3)
2.156(3)
2.112(3)
2.111(3)
–
2.06(2)
2.193(15)
2.06(2)i
2.193(15)i
–
M–P1
2.322(2)
–
M–Cl1
M-Cl2
M–centroid 1
M–centroid 1
M1–M2
–
–
2.4068(12)
–
1.785
–
–
2.3789(10)
2.4004(12)
1.689
1.690
6.073(1)
2.402(6)
2.402(6)i
1.818
peared around 1449–1458 and 1437 cmꢁ1
change only in the position of mC of thiazole suggested that
, respectively. The
1.820
–
–
@
N
1.818
6.558(2)i
the coordination of the metal ion is through nitrogen atom of thi-
azole not with the sulfur atom. In addition to these bands a strong
band in the region 843 cmꢁ1 has been assigned to counter ion PF6.
In the mass spectra they give, as expected, rise to the corre-
sponding [M]+ molecular peaks m/z at 537, 593, 750, 820, 560
and 649, respectively. The 1H NMR spectrum of free ligand L
(4,40-bis(2-pyridyl-4-thiazole)) exhibit a characteristic set of five
resonances for the thiazole and pyridyl ring protons. Upon coordi-
nation with the metal atom, the mononuclear cationic complexes
[1]PF6 to [6]PF6 exhibit between seven and nine distinct reso-
Angles (°)
N1–M–N2
N3–M–N4
N1–M–P1
N2–M–P1
N1–M–Cl1
N2–M–Cl1
N3–M–Cl2
N4–M–Cl2
76.3(3)
–
89.1(2)
91.69(19)
–
–
–
–
76.51(13)
–
77.12(12)
77.04(11)
75.5(8)
75.5(8)i
87.36(9)
94.54(9)
–
–
82.43(9)
83.90(8)
82.54(10)
85.19(10)
84.2(6)
89.7(8)
84.2(6)i
89.7(8)i
i = 1 ꢁ x, ꢁy, z.

230
K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
Fig. 4. Molecular structure of complex 12 showing ellipsoids at the 50% probability
level Hydrogen atoms, PF6 anions and solvent molecule are omitted for clarity.
Fig. 1. Molecular structure of complex 3 showing ellipsoids at the 50% probability
level. Hydrogen atoms, PF6 anion and solvent molecule are omitted for clarity.
1.69, as well as a septet at d = 2.70 for the protons of the isopropyl
group and a singlet at 2.33 ppm for methyl proton of p-cymene li-
gand. The two doublets observed at 5.59 and 5.39 ppm correspond
to the aromatic p-cymene ring CH protons. This unusual pattern is
due to the diastereotopic methyl protons of the isopropyl group
and aromatic protons of the p-cymene ligand, since the ruthenium
atom is stereogenic due to the coordination of four different ligand
atoms and chiral nature of metal atom [53–55]. Complex [3]PF6
exhibited a strong peak at d = 4.58 which is assigned to cyclopen-
tadienyl ligand and complexes [4]PF6 to [6]PF6 exhibit a strong
peak at d = 2.01, 2.11 and 1.84 for the pentamethylcyclopentadie-
nyl ligand, respectively, which are slightly shifted downfield in
comparison to the starting precursors.
The 31P {1H} NMR spectra of complexes [3]PF6 and [4]PF6 exhi-
bit a strong peak at d = 49.34 and 51.54, respectively, for the tri-
phenylphosphine ligand which is shifted down field as compared
to starting neutral precursors d = 42.00 and 38.50 [56,57]. This
down field chemical shift of phosphorus nucleus indicates the for-
mation of cationic complexes.
Fig. 2. Molecular structure of complex 5 showing ellipsoids at the 50% probability
level. Hydrogen atoms, PF6 anion and solvent molecule are omitted for clarity.
3.2. Crystal structure analysis of [(
and [(
5-C5Me5)Rh(L)(Cl)]PF6 ([5]PF6)
g
5-C5H5)Ru(PPh3)(L)]PF6 ([3]PF6)
g
The molecular structure of [(
and [(
g
5-C5H5)Ru(PPh3)(L)]PF6 [3]PF6
5-C5Me5)Rh(L)(Cl)]PF6 [5]PF6 have been established by sin-
g
gle-crystal X-ray structure analysis. Both complexes show a typical
piano-stool geometry with the metal center coordinated by the
aromatic ligand, a terminal triphenylphosphine or chloride and a
chelating N,N0-ligand (see Figs. 1 and 2). The metal atom is in octa-
hedral arrangement and the L ligand is found to coordinate
through the N1 atom of the pyridine moiety and the N2 atom of
the thiazolyl ring to generate a five-membered ring metallo-cycle
(see Figs. 1 and 2). In these complexes, the S atom points away
from the metal center and show no interaction with neighboring
cations. Selected bond lengths and angles for complexes [3]PF6
and [5]PF6 are presented in Table 2. In the mononuclear complexes
[3]PF6 and [5]PF6 the metal to nitrogen (N1) bond distance
(2.067(8) and 2.100(3) Å) of the pyridine is shorter than the
corresponding metal–thiazole nitrogen distance (2.105(8) and
Fig. 3. Molecular structure of complex 8 showing ellipsoids at the 50% probability
level. Hydrogen atoms, PF6 anions and solvent molecules are omitted for clarity.
2.146(4) Å), which are comparable to those in [(
uCl(C5H4N-2-CH@N@C6H4-p-NO2)]PF6 [58], [Ru(mes)Cl{C5H4N-2-
C(Me)@N(CHMePh)}]BF4 [59], [(
5-C5Me5)RhCl(C5H4N-2-CH@N@
C6H4-p-NO2)]BF4 [60], but unlike in [(
1,8-naphthyridine)Cl]PF6, [53], [(
(2-pyridyl)pyrazine)]BF4 [61] [(
g
6-C6Me6)R-
nances assignable to thiazolyl and pyridyl ring protons of the L
[4,40-bis(2-pyridyl-4-thiazole)] ligand indicating formation of
mononuclear complexes. Besides these resonances complex
[1]PF6 exhibit a singlet at d = 5.95 for the protons of the benzene
ligand and complex [2]PF6 exhibits two doublets at d = 1.71 and
g
g
g
6-C6H6)Ru(2-(2-thiazolyl)-
6-p-iPrC6H4Me)RuCl(2,3-bis
g
6-C6H6)RuCl(2-(1-imidazol-2-
yl)pyridine)]PF6 [62] and [(g5-C5Me5)Ir(2-(20-pyridyl)imidaz-

K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
231
+
N
R
S
R
Ru
N
Cl
Cl
L (2 e.q)
MeOH
Ru
N
Cl
Cl
Cl
Ru
N
S
R
: 1
: 2
R
=
+
N
S
R
N
R
Ru
L (1 e.q)
MeOH
N
Ph3P
Ru
Cl
Ph3P
N
S
Ph3P
: 3
R
=
: 4
+
N
S
M
N
Cl
Cl
L (2 e.q)
Cl
Cl
MeOH
M
N
Cl
M
N
S
M = Rh : 5
M = Ir : 6
Scheme 1.
ole)Cl]PF6 [63]. Accordingly, there is no significant difference in the
M - Cl bond length in 5 [2.407(12) Å] and reported values [64]. The
N(1)–M(1)–N(2) bond angle in complexes 3 and 5 is found to be
[76.40(3)°] and [76.51(1)°], respectively, which are similar to those
[N(1)–Ru(1)–N(2) = 76.5(2)°] [59] and [(
g
6-p-iPrC6H4Me)RuCl(2,3-
bis(2-pyridyl)quinoxaline)]+ [N(1)–Ru(1)–N(2) = 76.2(2)°] [65].
The distances between the ruthenium atom and the centroid of
the
tance between the rhodium atom and the centroid of the
g
5-C5H5 ring is 1.820 Å in complex [3]PF6, whereas the dis-
of complexes [(g
6-p-iPrC6H4Me)RuCl(2,3-bis(2-pyridyl)pyrazine)]+

232
K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
g
5-C5Me5 ring is 1.785 Å in complex [5]PF6. These bond distances
are comparable to those in the related complex cations [Ru(g5
C5H5)(PPh3)(
2-paa)]+, [Ru( 5-C5H5)( 1-dppm)( 2-paa)]+ [63] and
[(
5-C5Me5)Rh(3,6-bis(2-pyridyl)4-phenylpyridazine)Cl]PF6
(1.789 Å) and [(
5-C5Me5)Ir(pyNp)Cl]PF6 (PyNp = 2-(2-pyridyl)-
3.3. Synthesis of the dinuclear complexes [7](PF6)2–[12](PF6)2 as
hexafluorophosphate salts
-
j
g
j
j
g
The reaction of the chloro bridged dinuclear complexes [(g6
-
-
g
arene)Ru(l g l
-Cl)Cl]2 (arene = C6H6, p-PriC6H4Me); [( 5-C5Me5)M(
1,8-naphthyridine) (1.79 Å) [53].
Cl)Cl]2 (M = Rh, Ir) with 1 equiv. of ligand L [4,40-bis(2-pyridyl-4-
2+
R
S
N
R
Ru
Ru
N
Cl
Cl
Cl
Ru
L (1 e.q)
MeOH
N
R
Cl
Cl
Cl
Ru
N
S
R
7
:
:
R
=
8
2+
S
N
R
Ru
PPh3
N
R
Ru
L (1/2 e.q)
MeOH
N
Ph3P
R
Ru
Cl
N
Ph3P
S
Ph3P
:
:
9
R
=
10
2+
S
N
M
Cl
M
N
Cl
L (1 e.q)
MeOH
Cl
M
Cl
Cl
N
Cl
M
N
S
M = Rh : 11
M = Ir : 12
Scheme 2.

K.T. Prasad et al. / Journal of Organometallic Chemistry 695 (2010) 226–234
233
thiazole)] in methanol results in the formation of the orange color,
Ir(III)) bonded to an
g
6-p-iPrC6H4Me or
g
5-C5Me5 ligands, respec-
air-stable dinuclear dicationic complexes [{(
(7), [{(
6-p-iPrC6H4Me)RuCl}2(L)]2+ (8), [{(
(11) and [{(
pentadienyl/pentamethylcyclopentadienyl ruthenium triphenyl-
phosphine complexes [(
5-Cp)Ru(PPh3)2Cl] (Cp = C5H5 and
C5Me5) and half equivalent of ligand L in methanol at 55 °C leads
to the formation of [{(
5-C5H5)Ru(PPh3)}2(L)]2+ (9) and [{(g5
g
6-C6Me6)RuCl}2(L)]2+
5-C5Me5)RhCl}2(L)]2+
tively, which are bridged by the L ligand through its nitrogen atoms.
Interestingly, the dinuclear dication [8](PF6)2 reveals a trans confor-
mation of the two chloro ligands (see Fig. 3), while the cis isomer is
observed in the case of [12](PF6)2 (see Fig. 4). The average distances
g
g
g
5-C5Me5)IrCl}2(L)]2+ (12). Similarly reactions of cyclo-
g
between the metal atom and the carbon atoms of the g6
-
p-iPrC6H4Me ring are at 2.20 Å. This bond length is comparable to
those in related
6-p-iPrC6H4Me ruthenium complexes such as
[(
6-p-iPrC6H4Me)Ru(2-acetylthiazoleazine)Cl]PF6 [2.10 Å] [66]
and [(
6-p-iPrC6H4Me)Ru(2-(2-thiazolyl)-1,8-naphthyridine)Cl]PF6
g
-
g
C5Me5) Ru(PPh3)}2(L)]2+ (10). All these complexes are isolated as
their hexafluorophosphate salts (Scheme 2) and they were charac-
terized by mass, 1H NMR spectrometry, and elemental analyses. In
addition to these complexes 9 and 10 were also characterized by
31P NMR spectrometry. On top of these mono and dinuclear com-
plexes we were tried to synthesize hetero dinuclear, tri and tetra
nuclear complexes by using varieties of transition metals, but re-
sults were not fruitful.
g
g
[2.19 Å] [53]. The Ru–N bond distances ranging from 2.093(3) to
2.157(3) Å are longer than in the mononuclear complex [3]PF6
[2.067(8) and 2.105(8) Å], while the ruthenium-chlorine bond dis-
tances are comparable. In complex [8](PF6)2, the isopropyl group
of the p-cymene ligand is located opposite to the halide ligand in or-
der to limit steric interaction. The average distances between the
metal atom and the carbon atoms of the
2.18 Å, which is almost identical to those reported iridium or
rhodium complexes such as [(
5-C5Me5)IrCl((S)-1-phen-
ylethylsalicylaldiimine)] [2.17 Å] and [(
5-C5Me5)RhCl((S)-1-phen-
ylethylsalicylaldiimine)] [2.16 Å] [67]. The Ir–Cl bond lengths are
2.406(2) Å [in [12](PF6)2], which is almost identical to the reported
cationic polypyridyl iridium complex [{(g5-C5Me5)IrCl}2(2,20-bipy-
rimidine)]2+ [2.408(8) Å] [68], while Ir–N bond distances are similar
to mononuclear rhodium complex ([5]PF6). The N(1)–M(1)–N(2)
and N(3)–M(2)–N(4) bond angles in complex [3]PF6 and [5]PF6
are found to be [77.13(1)° and 77.03(1)°] and [75.61(9)° and
75.61(9)°], respectively. The distances between the ruthenium
atom and the centroid of the
complex [8](PF6)2, whereas the distance between the iridium atom
and the centroid of the
5-C5Me5 ring is 1.811 Å in complex
[12](PF6)2. These bond distances are comparable to those in the re-
lated complex cations [(
6-p-iPrC6H4Me)Ru(2-acetylthiazole-
azine)Cl]PF6 [66] and [(
5-C5Me5)Ir(pyNp)Cl]PF6 (PyNp=2-(2-
Infrared spectra of these dinuclear complexes [7](PF6)2 to
[12](PF6)2, showed a similar trend as the mononuclear cationic
complexes [1]PF6 to [6]PF6. In the mass spectra the complexes 7,
8, 11 and 12 hexafluorophosphate salts give rise to two main
peaks; a minor peak with an approximately 50% intensity attrib-
uted to [M2++PFꢁ6 ]+ at m/z 891, 1008, 943 and 1122, respectively,
and a major peak which corresponds to loss of [(arene)MCl]+ frag-
ment to the formation of mononuclear cations 1, 2, 5 and 6 at m/
z = 537, 593, 560 and 649, respectively.
g
5-C5Me5 ring is at
g
g
The 1H NMR spectra of the dinuclear cationic complexes
[7](PF6)2 to [12](PF6)2 exhibited five distinct resonances assignable
to thiazolyl ring and pyridyl ring protons of the L ligand indicating
formation of dinuclear complexes. Besides these resonances com-
plex [7](PF6)2 exhibit two singlets at d = 6.01 and d = 5.99 for the
protons of the benzene ligands and complex [8](PF6)2 exhibits four
doublets at d = 1.38–0.98, and septets at d = 2.42 for the protons of
the isopropyl group. The four doublets observed at d = 5.86–5.38
correspond to the aromatic p-cymene ring CH protons. Complexes
[9](PF6)2 to [12](PF6)2 exhibit a strong peak at d = 4.86 and 1.97,
2.15, 1.54 for the cyclopentadienyl and pentamethylcyclopentadie-
nyl ligands, which are slightly shifted downfield in comparison to
the starting complexes. In the dinuclear complexes each arene li-
gand has exhibited set of individual resonances for each set of pro-
tons due to free rotation in solution ([7](PF6)2 and [8](PF6)2), where
as pentamethylcyclopentadienyl ligand containing complexes
([11](PF6)2 and [12](PF6)2) exhibits only one set of resonance for
both pentamethylcyclopentadienyl ligands due to center of inver-
sion in these molecules.
g
6-p-iPrC6H4Me ring is 1.689 Å in
g
g
g
pyridyl)-1,8-naphthyridine) (1.79 Å) [53].
3.5. UV–vis spectroscopy
Electronic absorption spectra of complexes [1]PF6 to [12](PF6)2
were acquired in acetonitrile, at 10ꢁ5 M concentration in the range
250–550 nm. The spectral data of these complexes conformed well
to their respective formulations. The spectra of these complexes are
characterized by two main features, viz., an intense ligand-localized
*
or intra-ligand
p
?
p
transition in the ultraviolet region and me-
The 31P NMR spectra of complexes [9](PF6)2 and [10](PF6)2 exhibit
a strong peak at d = 49.28 and 51.33, respectively, which are shifted
downfield as compared to starting neutral precursors d = 42.00 and
38.50 [56,57], respectively. This down field chemical shift of phos-
phorus nucleus indicates the formation of cationic complexes.
*
tal-to-ligand charge transfer (MLCT) d
p(M) ?
p
(L – ligand) bands
in the visible region [69]. Since the low spin d6 configuration of the
mononuclear complexes provides filled orbitals of proper symme-
try at the Ru(II), Rh(III) and Ir(III) centers, these can interact with
*
p orbitals of the ligands. All the mononuclear complexes
low lying
[1]PF6 to [6]PF6 show only an intense band in the region 333–
341 nm, while all dinuclear complexes [7](PF6)2 to [12](PF6)2 show
two bands, one is at 310–312 nm with high intensity as well as a
second one at 355–358 nm observed as a shoulder peak (see
3.4. Crystal structure analysis of [{(
([8](PF6)2) and [{(
5-C5Me5)IrCl}2(L)]2+ ([12](PF6)2)
g
6-p-iPrC6H4Me)RuCl}2(L)]2+
g
The molecular structure of [{(
g
6-p-iPrC6H4Me)RuCl}2(L)]2+
5-C5Me5)IrCl}2(L)]2+ ([12](PF6)2) have been
Fig. 5). The high intensity band in UV region for both mononuclear
([8](PF6)2) and [{(
g
*
and dinuclear complexes is assigned to inter and intra-ligand
*
p–p /
established by single-crystal X-ray structure analysis. Selected
bond lengths and angles for complexes [8](PF6)2 and [12](PF6)2
are presented in Table 2. In the dinuclear complexes [8](PF6)2 and
[12](PF6)2, the metal centers are stereogenic. However, while
[8](PF6)2 crystallized as racemic crystals with the centrosymmetric
n–
p transitions [68,70,71], while the low energy absorption band
in the visible region for dinuclear complexes is assigned to metal-
*
to-ligand charge transfer (MLCT) (t2g–p ). Representative spectra
of these complexes are represented in Fig. 5.
ꢀ
space group P1, [12](PF6)2 crystallizes as a racemic mixture of enan-
tiopure crystals with the non-centrosymmetric space group P21212.
As well both the complexes show a typical piano-stool geometry
with the metal center coordinated by the aromatic ligand, a termi-
nal chloride and a chelating N,N-ligand (see Figs. 3 and 4). The com-
pounds [8](PF6)2 and [12](PF6)2 contain two metal centers (Ru(II) or
4. Conclusions
In summary, in this work ligand L [4,40-bis(2-pyridyl-4-thia-
zole)] reacted with series of arene and cyclopentadienyl ruthe-
nium, rhodium and iridium complexes yielded novel series of

234
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Appendix A. Supplementary material
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Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2009.10.007.
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