New neutral and cationic η6-arene ruthenium complexes with phosphine and amine ligands: Syntheses and molecular structures of [(η6-p-cymene)Ru(NH(2)CH(2)C(6)H (5))Cl2], [(η6-C6Me 6)Ru(PPh2Py)Cl2] and [(η6-C 6Me6)Ru(PPh2Py)Cl]+

Article abstract of DOI:10.1016/j.poly.2004.09.031

The dimeric complex [(η⁶-C₆Me₆) Ru(μ-Cl)Cl]₂ reacts with diphenyl-2-pyridyl-phosphine to yield a neutral P-coordinated ruthenium(II) complex [(η⁶-C ₆Me₆)Ru(PPh₂Py)Cl₂] as well as a cationic P,N-chelating complex [(η⁶-C₆Me ₆)Ru(PPh₂Py)Cl]⁺. The monomeric complex [(η⁶-p-cymene)Ru(PPh₃)Cl₂] can react with amine ligands to yield chiral complexes. Representative complexes have been characterized by single-crystal X-ray study. The complex [{(η⁶-p- cymene)Ru(μ-Cl)Cl}₂] (1) reacts with benzylamine to give a neutral N-coordinated complex of the type [(η⁶-p-cymene)Ru(NH ₂CH₂C₆H₅)Cl₂] (2). The complex [(η⁶-p-cymene)Ru(PPh₃)Cl₂] (3) reacts with amine ligands to yield chiral complexes [(η⁶-p- cymene)Ru(PPh₃)(NH₂-R)Cl]⁺ [R = CH ₂C₆H₅ (4a), p-ClC₆H₄ (4b), p-NO₂C₆H₄ (4c)]. Complexes 1 and 3 react with N,N-donor chelating 1,2-phenylenediamine (PDA) giving cationic complexes 5 and 6, respectively. The complex [(η⁶-C₆Me ₆)Ru(μ-Cl)Cl]₂ (7) reacts with diphenyl-2- pyridylphosphine to yield a neutral P-coordinated ruthenium(II) complex [(η⁶-C₆Me₆)Ru(PPh₂Py)Cl ₂] (8) as well as a cationic P,N-chelating complex [(η⁶-C₆Me₆)Ru(PPh₂Py)Cl] ⁺ (9). The complex 9 undergoes substitution reactions with acetonitrile and 1,1-diphenyl-2-propyn-1-ol ligands. These complexes were characterized by FT-IR and FT-NMR spectroscopy as well as by analytical data. The molecular structures of the representative complexes [(η⁶-p- cymene)Ru(NH₂CH₂C₆H₅)Cl ₂] (2), [(η⁶-C₆Me₆)Ru(PPh ₂Py)Cl₂] (8) and [(η⁶-C₆Me ₆)Ru(PPh₂Py)Cl]BF₄ (9) were established by single-crystal X-ray diffraction studies.

Full text of DOI:10.1016/j.poly.2004.09.031

Polyhedron 23 (2004) 3115–3123
www.elsevier.com/locate/poly
New neutral and cationic g6-arene ruthenium complexes with
phosphine and amine ligands: syntheses and molecular structures
of [(g6-p-cymene)Ru(NH2CH2C6H5)Cl2],
[(g6-C6Me6)Ru(PPh2Py)Cl2] and [(g6-C6Me6)Ru(PPh2Py)Cl]+
a
P. Govindaswamy , Yurij A. Mozharivskyj , Mohan Rao Kollipara
b
a,
*
a
Department of Chemistry, North Eastern Hill University, Shillong 793 022, India
b
Ames Laboratory, Iowa State University of Science and Technology, Ames, Iowa, IA 50011, USA
Received 27 August 2004; accepted 20 September 2004
Abstract
The complex [{(g6-p-cymene)Ru(l-Cl)Cl}2] (1) reacts with benzylamine to give a neutral N-coordinated complex of the type [(g6-
p-cymene)Ru(NH2CH2C6H5)Cl2] (2). The complex [(g6-p-cymene)Ru(PPh3)Cl2] (3) reacts with amine ligands to yield chiral com-
plexes [(g6-p-cymene)Ru(PPh3)(NH2-R)Cl]+ [R = CH2C6H5 (4a), p-ClC6H4 (4b), p-NO2C6H4 (4c)]. Complexes 1 and 3 react with
N,N-donor chelating 1,2-phenylenediamine (PDA) giving cationic complexes 5 and 6, respectively. The complex [(g6-
C6Me6)Ru(l-Cl)Cl]2 (7) reacts with diphenyl-2-pyridylphosphine to yield a neutral P-coordinated ruthenium(II) complex [(g6-
C6Me6)Ru(PPh2Py)Cl2] (8) as well as a cationic P,N-chelating complex [(g6-C6Me6)Ru(PPh2Py)Cl]+ (9). The complex 9 undergoes
substitution reactions with acetonitrile and 1,1-diphenyl-2-propyn-1-ol ligands. These complexes were characterized by FT-IR and
FT-NMR spectroscopy as well as by analytical data. The molecular structures of the representative complexes [(g6-p-cym-
ene)Ru(NH2CH2C6H5)Cl2] (2), [(g6-C6Me6)Ru(PPh2Py)Cl2] (8) and [(g6-C6Me6)Ru(PPh2Py)Cl]BF4 (9) were established by sin-
gle-crystal X-ray diffraction studies.
ꢀ 2004 Elsevier Ltd. All rights reserved.
Keywords: Hexamethylbenzene; p-Cymene; Diphenyl-2-pyridylphosphine; Amines; Ruthenium complexes
1. Introduction
had earlier reported the reactivity differences of p-cym-
ene ruthenium(II) and hexamethylbenzene ruthe-
nium(II) dimers towards azide and pyrazoles [5,6].
Recent advances in catalytic amination have been
based on the use of early transition metal and f-block
element complexes [7]. However, catalytic additions
of amines, H-NR2, to non-activated double or triple
bonds mediated by late-transition-metal complexes
are still rare [7].
Arene ruthenium(II) complexes have been the sub-
ject of intense research in the field of organometallic
chemistry during recent years [1]. The catalytic activity
of these complexes ranges from hydrogen transfer [2] to
ring closing metathesis [3]. Anti-tumor activity exhib-
ited by some water-soluble arene ruthenium(II) com-
plexes has also evoked interest in recent years [4]. We
Diphenyl(2-pyridyl)phosphine (Fig. 1) is a versatile lig-
and which can coordinate to a metal in monodentate,
chelating and bridging modes, depending on the require-
ments at the metal center [8,9]. Recently, we had con-
ducted reactivity studies of this ligand with [Cp*MCl2]2
*
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).
0277-5387/$ - see front matter ꢀ 2004 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2004.09.031

3116
P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
NH2), 4.14 (t, 2H, JH–H = 7.64 Hz, CH2), 5.22 (d, 2H,
JH–H = 5.88 Hz, cymene), 5.39 (d, 2H, JH–H = 5.88 Hz,
cymene), 7.31–7.38 (m, 5H, Ph).
N
P
IR (KBr pellets, cmꢀ1): m(N–H) 3287 (s), 3221 (s). IR
(CsI pellets, cmꢀ1): m(Ru–Cl) 286 (s).
UV–vis (CH2Cl2): kmax = 393 nm.
Fig. 1.
2.2. Preparation of chiral complexes
(M = Rh, Ir) dimers [10]. In a continuation of our previ-
ous work, we report in this communication the syntheses
of neutral and chiral amine complexes of p-cymene ruthe-
nium as well as hexamethylbenzene ruthenium complexes
with the diphenyl(2-pyridyl)phosphine ligand.
2.2.1. Preparation of [(g6-p-cymene)Ru(PPh3)(NH2
CH2C6H5)Cl]PF6 (4a)
A mixture of [(g6-p-cymene)Ru(PPh3)Cl2] (3) (0.1 g,
0.175 mmol), benzylamine (0.028 g, 0.263 mmol) and
NH4PF6 (0.043 g, 0.263 mmol) in dichloromethane
and methanol (2:1) (15 ml) mixture was stirred at room
temperature for 2 h. The orange-yellow solution was
concentrated to dryness. The residue was dissolved in di-
chloro-methane and filtered to remove NH4Cl. The fil-
trate was concentrated to 2 ml, and addition of excess
hexane gave an orange-yellow complex. The complex
was filtered and washed with diethylether and dried un-
der vacuum.
2. Experimental
All the solvents were dried and distilled before use
following the standard procedures. RuCl3 Æ 3H2O was
purchased from Arora Matthey Ltd. and used as
received. a-Phellandrene (Fluka), hexamethylbenzene
(Acros Organics), benzylamine (Merck), diphenyl(2-pyr-
idyl)phosphine (Aldrich) and 1,1-diphenyl-2-propyn-1-
ol (Aldrich) were used as received. The precursor
complexes [{(g6-arene)Ru(l-Cl)Cl}2] [arene = p-cymene
Yield: 71.01% (0.098 g). Elemental Anal. Calc. (%) for
C35H38RuNClP2F6: C, 53.54; H, 4.87; N, 1.78. Found:
C, 53.51; H, 4.66; N, 1.82%.
[(g6-p-cym-
1H NMR (CDCl3, d): 1.19 (d, 3H, JH–H = 6.36 Hz,
CH3), 1.34 (d, 3H, JH–H = 6.76 Hz, CH3), 2.17 (s, 3H,
CH3), 2.72 (b, 2H, NH2), 2.98 (sep, 1H, CH), 4.08 (t,
2H, JH–H = 10.4 Hz, CH2), 5.29 (d, 2H, JH–H = 5.64
Hz, cymene), 5.42 (d, 2H, JH–H = 5.64 Hz, cymene),
7.54–7.17 (m, 20H, Ph).
(1),
hexamethylbenzene
(7)]
and
ene)Ru(PPh3)Cl2] (3) were prepared according to the lit-
erature procedures [11,12]. Elemental analyses were
performed in a Perkin–Elmer 2400 CHN/O analyzer.
Infrared spectra were recorded on a Perkin–Elmer
Model 983 spectrophotometer with samples prepared
as KBr and CsI pellets. Electronic spectra were recorded
on a Hitachi-300 spectrophotometer. NMR spectra were
taken on Bruker AMX-400 (400 MHz) and Bruker
ACF-300 (300 MHz) spectrometers with tetramethylsi-
lane as an internal standard. 31P {1H} NMR chemical
shifts are reported relative to H3PO4 (85%).
31P {1H} NMR (CDCl3, d): 36.05 (s).
IR (KBr pellets, cmꢀ1): m(N–H) 3287 (s), 3224 (s),
m(P–F) 839 (s). IR (CsI pellets, cmꢀ1): m(Ru–Cl) 276 (s).
2.2.2. Preparation of [(g6-p-cymene)Ru(PPh3)(NH2
C6H4-p-Cl)Cl]BF4 (4b)
A mixture of [(g6-p-cymene)Ru(PPh3)Cl2] (3) (0.1 g,
0.175 mmol), p-chloroaniline (0.044 g, 0.35 mmol) and
NH4BF4 (0.037 g, 0.35 mmol) in methanol was refluxed
for 2 h. The solvent was removed under reduced pres-
sure. The residue was dissolved in CH2Cl2 and then fil-
tered. The solution was concentrated to 2 ml and an
excess of hexane was added for precipitation. The or-
ange compound was washed with diethylether and dried
under vacuum.
2.1. Preparation of [(g6-p-cymene)Ru(NH2CH2C6H5)
Cl2] (2)
A mixture of [{(g6-p-cymene)Ru(l-Cl)Cl}2] (1) (0.1 g,
0.163 mmol) and benzylamine (0.44 g, 0.408 mmol) in
dichloromethane (20 ml) was stirred at room temperature
for 3 h. The orange solution was concentrated under re-
duced pressure. The residue was extracted with dichloro-
methane and filtered through a short silica gel column.
The resulting solution was reduced in volume to about 2
ml and hexane (20 ml) was added to give an orange-yellow
compound, which was recrystallized from the mixture of
dichloromethane and hexane to give orange crystals.
Yield: 89.62% (0.12 g). Elemental Anal. Calc. (%) for
C17H23RuNCl2: C, 49.39; H, 5.61; N, 3.38. Found: C,
49.41; H, 5.94; N, 3.34%.
Yield: 70.23% (0.092 g). Elemental Anal. Calc. (%) for
C34H35RuNCl2PBF4: C, 54.64; H, 4.72; N, 1.87. Found:
C, 54.61; H, 4.68; N, 1.84%.
1H NMR (CDCl3, d): 1.10 (d, 3H, JH–H = 6.92 Hz,
CH3), 1.25 (d, 3H, JH–H = 6.92 Hz, CH3), 2.16 (s, 3H,
CH3), 2.87 (sep, 1H, CH), 4.90 (s, 2H, NH2), 4.98 (d,
2H, JH–H = 5.84 Hz, cymene), 5.03 (d, 2H, JH–H = 5.4
Hz), 5.08 (d, 2H, JH–H = 5.84 Hz, cymene), 5.23 (d,
2H, JH–H = 6.08 Hz), 7.31–7.88 (m, 15H, Ph).
31P {1H} NMR (CDCl3, d): 21.25 (s).
1H NMR (CDCl3, d): 1.30 (d, 6H, JH–H = 6.96 Hz,
CH3), 2.23 (s, 3H, CH3), 2.98 (sep, 1H), 3.17 (b, 2H,

P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
3117
IR (KBr pellets, cmꢀ1): m(N–H) 3429 (s), 3239 (s),
m(B–F) 1096 (s). IR (CsI pellets, cmꢀ1): m(Ru–Cl) 273 (s).
[{(g6-p-cymene)Ru(l-Cl)Cl}2] (1). The complex was iso-
lated as an orange-red micro-crystalline solid.
Yield: 70.8% (0.097 g). Elemental Anal. Calc. (%) for
C34H37RuN2PB2F8: C, 52.40; H, 4.78; N, 3.59. Found:
C, 52.06; H, 4.82; N, 3.37%.
2.2.3. Preparation of [(g6-p-cymene)Ru(PPh3)(NH2-
C6H4-p-NO2)Cl]BF4 (4c)
A mixture of [(g6-p-cymene)Ru(PPh3)Cl2] (3) (0.1 g,
0.175 mmol), p-nitroaniline (0.048 g, 0.35 mmol) and
NH4BF4 (0.037 g, 0.35 mmol) in methanol was stirred
at room temperature for 14 h. A yellow colored product
separated out. The complex was washed with diethyl-
ether and dried under vacuum.
Yield: 71.42% (0.095 g). Elemental Anal. Calc. (%) for
C34H35RuN2O2ClPBF4: C, 53.88; H, 4.65; N, 3.69.
Found: C, 53.82; H, 4.56; N, 3.71%.
1H NMR (CDCl3, d): 0.93 (d, 3H, JH–H = 6.69 Hz,
CH3), 1.11 (d, 3H, JH–H = 6.67 Hz, CH3), 2.20 (s, 3H,
CH3), 2.87 (sep, 1H), 4.61 (d, 4H, JH–H = 10.74 Hz,
NH2), 5.63 (d, 2H, JH–H = 5.85 Hz, cymene), 5.86 (d,
2H, JH–H = 5.85 Hz, cymene), 6.92 (d, 2H, JH–H = 6.46
Hz), 7.16–7.76 (m, 17H, Ph).
IR (KBr pellets, cmꢀ1): m(N–H) 3326(s), 3192(s), m(B–
F) 1089(s).
1H NMR (CDCl3, d): 1.12 (d, 3H, JH–H = 7.56 Hz,
CH3), 1.31 (d, 3H, JH–H = 6.92 Hz, CH3), 2.19 (s, 3H,
CH3), 2.95 (sep, 1H, CH), 4.40 (s, 2H, NH2), 5.37 (d,
2H, JH–H = 5.96 Hz), 5.50 (d, 2H, JH–H = 5.88 Hz, cym-
ene), 6.69 (d, 2H, JH–H = 5.86 Hz, cymene), 7.68–7.34
(m, 15H, Ph), 8.10 (d, 2H, JH–H = 8.96 Hz).
2.5. Preparation of [(g6-C6Me6)Ru(PPh2Py)Cl2] (8)
A mixture of [{(g6-C6Me6)Ru(l-Cl)Cl}2] (7) (0.1 g,
0.149 mmol) and diphenyl(2-pyridyl)phosphine (PPh2Py)
(0.098 g, 0.374 mmol) in dichloromethane (20 ml) was stir-
red at room temperature for 1 h. The orange solution was
concentrated to 3 ml and an excess of hexane was added
for precipitation. The orange microcrystalline product
was washed with diethylether and dried under vacuum.
Yield: 79.21% (0.141 g). Elemental Anal. Calc. (%) for
C29H32RuNCl2P: C, 58.29; H, 5.39; N, 2.34. Found: C,
58.32; H, 5.36; N, 2.39%.
1H NMR (CDCl3, d): 1.76 (s, 18H, HMB), 7.13–8.11
(m, 13H), 8.57 (d, 1H, JH–H = 6.24 Hz).
31P {1H} NMR (CDCl3, d): 25.88 (s). IR (CsI pellets,
cmꢀ1): m(Ru–Cl) 286 (s).
31P {1H} NMR (CDCl3, d): 26.54 (s).
IR (KBr pellets, cmꢀ1): m(N–H) 3317 (s), 3246 (s),
m(NO2) 1520 (s), 1341 (s), m(B–F) 1096 (s). IR (CsI pel-
lets, cmꢀ1): m(Ru–Cl) 283 (s).
2.3. Preparation of [(g6-p-cymene)Ru(PDA)Cl]BF4 (5)
(PDA = 1,2-phenylenediamine)
A suspension of the complex [{(g6-p-cymene)Ru(l-
Cl)Cl}2] (1) (0.1 g, 0.163 mmol) in methanol (20 ml)
was treated with 1,2-phenylenediamine (0.035 g, 0.326
mmol) and NH4BF4 (0.05 g, 0.489 mmol) and allowed
to stir at room temperature for 10 h. The solvent was re-
moved under reduced pressure. The orange mass was
dissolved in dichloromethane and filtered. The filtrate
was concentrated to 2 ml and an excess of hexane added
for precipitation. The orange-colored product was
washed with diethylether and dried under vacuum.
Yield: 58.55% (0.089 g). Elemental Anal. Calc. (%) for
C16H22RuN2ClBF4: C, 41.26; H, 4.76; N, 6.01. Found:
C, 41.42; H, 4.93; N, 5.96%.
2.6. Preparation of [(g6-C6Me6)Ru(PPh2Py)Cl]BF4 (9)
Method 1: A mixture of [{(g6-C6Me6)Ru(l-Cl)Cl}2]
(7) (0.1 g, 0.149 mmol), diphenyl(2-pyridyl)phosphine
(PPh2Py) (0.196 g, 0.748 mmol) and NH4BF4 (0.078 g,
0.748 mmol) in methanol were stirred at room tempera-
ture for 2 h. The yellow solution was concentrated under
reduced pressure. The yellow residue was dissolved in di-
chloro-methane and filtered. The filtrate was concen-
trated to 2 ml and an excess of hexane was added for
precipitation. The yellow-colored product was washed
with diethylether and dried under vacuum.
1H NMR (CDCl3, d): 0.86 (d, 3H, JH–H = 2.45 Hz,
CH3, cymene), 1.15 (d, 3H, JH–H = 2.91 Hz, CH3, cym-
ene), 2.26 (s, 2H, CH3, cymene), 3.00 (sep, 1H), 5.00 (d,
4H, JH–H = 12.23 Hz, NH2), 5.70 (d, 2H, JH–H = 5.76
Hz, cymene), 5.93 (d, 2H, JH–H = 5.76 Hz, cymene),
7.16 (dd, 2H, 2.27 Hz), 8.37 (d, 2H, 8.58 Hz).
Yield: 82.47% (0.16 g). Elemental Anal. Calc. (%) for
C29H32RuNClPBF4: C, 53.68; H, 4.97; N, 2.15. Found:
C, 53.61; H, 5.01; N, 2.03%.
1H NMR (CDCl3, d): 2.08 (s, 18H, HMB), 7.09–7.79
(m, 11H), 7.89 (t, 1H, JH–H = 4.36 Hz), 8.01 (t, 1H,
JH–H = 4.42 Hz), 8.67 (d, 1H, JH–H = 5.12 Hz).
31P {1H} NMR (CDCl3, d): ꢀ11.25 (s).
IR (KBr pellets, cmꢀ1): m(N–H) 3346 (s), 3232 (s),
m(B–F) 1082 (s).
2.4. Preparation of [(g6-p-cymene)Ru(PPh3)(PDA)]
(BF4)2 (6)
IR (KBr pellets, cmꢀ1): m(B–F) 1089 (s). IR (CsI pel-
lets, cmꢀ1): m(Ru–Cl) 280 (s).
Method 2: A mixture of the complex [(g6-C6Me6)R-
u(PPh2Py)Cl2] (8) (0.1 g, 0.167 mmol) and NH4BF4
(0.052 g, 0.501 mmol) in methanol (15 ml) was stirred
at room temperature for 4 h. The clear orange yellow
This complex was prepared by following the above-
mentioned procedure (5), except that the complex [(g6-
p-cymene)Ru(PPh3)Cl2] (3) was used in place of complex

3118
P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
solution was then rotary evaporated. The residue was ex-
tracted with dichloromethane and filtered to remove
insoluble material. The filtrate was then reduced to about
2 ml and addition of excess hexane gave a yellow solid.
Yield: 80.41% (0.156 g).
NH4BF4 (0.029, 0.27 mmol) was refluxed in methanol
(15 ml) under a nitrogen atmosphere for 3 h, the yellow
suspension gradually turning brown in color. The sol-
vent was removed under reduced pressure. The brown
solid was dissolved in CH2Cl2 and filtered. The filtrate
was concentrated to 2 ml and an excess of hexane was
added for precipitation. The brown colored product
was washed with diethylether and dried under vacuum.
Yield: 76.83% (0.063 g). Elemental Anal. Calc. (%) for
C44H42RuNPB2F8: C, 59.35; H, 4.75; N, 1.57. Found: C,
59.43; H, 4.69; N, 1.59%.
2.7. Preparation of [(g6-C6Me6)Ru(PPh2Py)
(NCCH3)](BF4)2 (10)
A mixture of complex 9 (0.06 g, 0.092 mmol) and
NH4BF4 (0.019 g, 0.184 mmol) was refluxed in acetonit-
rile (15 ml) under a nitrogen atmosphere for 2 h, and the
yellow solution turned light yellow in color. The solvent
was rotary evaporated. The yellow solid was dissolved in
CH2Cl2 and filtered. The filtrate was concentrated to 2
ml and an excess of hexane was added for precipitation.
The light yellow product was washed with diethylether
and dried under vacuum.
1H NMR (CDCl3, d): 1.83 (s, 18H, HMB), 7.15–7.71
(m, 14H), 8.05–8.08 (m, 6H), 8.29–8.31 (m, 3H), 8.95 (d,
1H, JH–H = 5.97 Hz).
31P {1H} NMR (CDCl3, d): ꢀ15.32 (s).
IR (KBr pellets, cmꢀ1): m(C@C@C) 1964(s), m(B–F)
1082(s).
Yield: 78.07% (0.089 g). Elemental Anal. Calc. (%) for
C31H35RuN2PB2F8: C, 50.23; H, 4.75; N, 3.78. Found:
C, 50.46; H, 4.57; N, 3.92%.
3. Crystallographic investigations
1H NMR (CDCl3, d): 2.06 (s, 18H, HMB), 2.18 (s,
3H, CH3), 7.69–8.01 (m, 13H, Ph), 8.76 (d, 1H).
31P {1H} NMR (CDCl3, d): ꢀ13.57 (s).
X-ray quality crystals of complex 2 were grown by
slow diffusion of hexane into a dichloromethane solu-
tion of the complex, while those of complex 8 were
grown by slow diffusion of diethyl ether into a dichloro-
methane solution. Crystals of complex 9 were grown by
slow diffusion of hexane into an acetone solution. The
orange crystals of complexes 2 and 8 and the yellow
crystals of complex 9 were mounted on a Bruker Apex
CCD diffractometer in a full reciprocal sphere equipped
with a CCD detector, and were used for data collection.
IR (KBr pellets, cmꢀ1): m(B–F) 1082 (s).
2.8. Preparation of [(g6-C6Me6)Ru(PPh2Py)
{@C@C@C(Ph)2}](BF4)2 (11)
A mixture of complex 9 (0.06 g, 0.092 mmol), 1,1-
diphenyl-2-propyn-1-ol (0.048 g, 0.23 mmol) and
Table 1
Crystal data and structure refinement details for complexes 2, 8 and 9 acetone
Formula
Mr
C
413.33
17H23Cl2NRu
C29H32Cl2NPRu
597.5
293 (2)
C32H38BClF4NOPRu
706.93
293 (2)
T (K)
293 (2)
0.71073
˚
Wavelength (A)
Crystal system
Space group
0.71073
monoclinic
C2/c
0.71073
monoclinic
P21
monoclinic
P21/c
˚
a (A)
11.8414(7)
10.0786(6)
15.1580(8)
102.817 (1)
1763.95(17)
4
15.6052(19)
8.7978(11)
37.107(5)
90.476 (2)
5094.4(11)
8
13.0710(11)
8.1669(7)
15.2210(12)
94.782 (1)
1619.2(2)
2
˚
b (A)
˚
c (A)
b (ꢁ)
3
˚
V (A )
Z
Crystal size (mm)
Dcalc (g cmꢀ3
F(000)
0.5 · 0.3 · 0.2
1.556
840
0.3 · 0.2 · 0.2
1.558
2448
0.3 · 0.2 · 0.2
1.450
724
)
h (ꢁ)
Reflections collected
Independent reflections (Rint
1.76–28.27
14969
4103 (0.0174)
1.10–24.85
14468
4104 (0.0497)
1.34–28.30
14227
7272 (0.0283)
)
Completeness to h
l (Mo Ka) (mm)
Data/parameters
28.27ꢁ – 93.8%
1.185
4103/0/173
24.85ꢁ – 92.7%
0.908
4104/0/253
28.30ꢁ – 95.0%
0.665
7272/1/327
Goodness-of-fit on F2
R1 [I > 2r(I)], wR2
R1, wR2 (all data)
1.033
1.257
1.077
0.0274, 0.0692
0.0299, 0.0705
0.856 and ꢀ0.695
0.0661, 0.1498
0.0809, 0.1625
1.152 and ꢀ0.795
0.0515, 0.1232
0.0594, 0.1278
1.249 and ꢀ0.451
ꢀ3
˚
Largest difference peak and hole (e A
)

P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
3119
X-ray intensity data were collected with graphite mono-
chromated Mo Ka radiation at 293(2) K, with the 0.3ꢁx
scan mode and 10 s per frame. The intensity data were
corrected for Lorentz and polarization effects. Absorp-
tion correction was done using the SAINT program
[13]. A summary of the crystal data, data collection
parameters and convergence results is compiled in Table
1. An empirical absorption correction was made by
modeling a transmission surface by spherical harmonics
employing equivalent reflections with I > 3r(I) (pro-
gram SADABS) [14]. The structure was solved by direct
methods [15]. All the non-hydrogen atoms were refined
anisotropically using the full-matrix least-squares tech-
nique on F2 using the SHELXL-97 software [16]. All the
hydrogen atoms were found from difference Fourier
synthesis after four cycles of an isotropic refinement
and as per the ‘‘riding’’ model. Figs. 2–4 display the OR-
TEP [17] representations of the molecules with 50%
probability thermal ellipsoids. Refinement converged
at final R1 values of 0.0274, 0.0661 and 0.0515 (for ob-
served data F) for complexes 2, 8 and 9, respectively.
Fig. 3. ORTEP diagram of complex 8 with 50% probability thermal
ellipsoids. Hydrogens are omitted for clarity of the figure.
4. Results and discussion
4.1. Amine complexes
The dinuclear complex [{(g6-p-cymene)Ru(l-Cl)Cl}2]
(1) undergoes a bridge cleavage reaction with benzylam-
ine to yield neutral complex 2 (Scheme 1). The complex
[(g6-p-cymene)Ru(PPh3)Cl2] (3) reacts with amines
resulting in the formation of chiral complexes (Scheme
2). Complexes 1 and 3 also react with 1,2-phenylenedi-
amine (PDA) giving the cationic complexes [(g6-p-cym-
ene)Ru(PDA)Cl]+ (5) and [(g6-p-cymene)Ru(PPh3)-
(PDA)]2+ (6) (Scheme 1, reaction (1)). These complexes
are stable in air and are soluble in polar solvents such as
dichloromethane and acetone, but insoluble in non-po-
lar solvents such as pentane and hexane. The infrared
spectra of these complexes show strong bands in the
range 3221–3429 cmꢀ1 for the mN–H mode of the amine
group [5b] and a strong band in the range 273–286
Fig. 2. ORTEP diagram of complex 2 with 50% probability thermal
ellipsoids. Hydrogens are omitted for clarity.

3120
P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
BF
4
PPh
3
Cl
MeOH
H N-R
2
Ru
Cl
+
Ru
Cl
NH BF
4
N--R
4
PPh
H
2
3
R = CH -C H (4a)
6 5
2
p-Cl-C6H4 (4b)
Complex 3
p-NO -C H (4c)
2
6 4
Scheme 2.
1
The H NMR spectrum of complex 2 exhibits a dou-
blet at 1.30 ppm (J = 6.96 Hz) while a septet at 2.98 ppm
is observed for the isopropyl group protons. The two
doublets observed at 5–6 ppm correspond to the aro-
matic p-cymene ring CH protons. The phenyl group of
the benzylamine ligand gives multiplets in the range
1
7.31–7.40 ppm. The H NMR spectra of the mononu-
clear complexes 4 exhibit two doublets for the methyl
protons of the isopropyl group. This is due to the dia-
stereotopic nature of these complexes (4a–c) (Scheme
2) since the ruthenium metal is a chiral center. The com-
plexes 5 and 6 also exhibit two doublets for the methyl
groups of the p-cymene ligand due to the steric nature
of the bulky 1,2-phenylenediamine ligand.
(BF
)
4 2
MeOH, 10 h.
NH BF
PPh
Cl
3
Ru
Cl
+ PDA
Ru
4
4
PPh
3
NH
2
H N
2
Complex 3
Complex 6
ð1Þ
1
The H NMR spectrum of complex 5 exhibits two
doublets at 7.16 and 8.23 ppm for the ring protons of
1,2-phenylenediamine. In the case of complex 6, the sig-
nals for these protons merge with those for the phenyl
group protons of the triphenylphosphine ligand, thereby
exhibiting multiplets in the range 6.93–7.76 ppm. Both
Fig. 4. ORTEP diagram of complex 9 with 50% probability thermal
ellipsoids. Hydrogens are omitted for clarity.
cmꢀ1 for the mRu–Cl mode [5b]. All these complexes (4–6)
exhibit a strong band at 1089 cmꢀ1 due to the mB–F mode
of the BF4 group.
Cl
Cl
Ru
Ru
Cl
Cl
Cl
Cl
Ru
Ru
Cl
Cl
complex 1
benzylamine
MeOH
10 h
CH Cl
complex 7
2
2
stirr 3 h.
PDA
NH4BF4
PPh Py
2
PPh2Py
MeOH
NH BF
4
4
CH Cl
2
2
Cl
Cl
BF
4
BF
4
Ru
Cl
Ru
Cl
NH
H
N
2
Ru
N
NH BF
4
MeOH
4
Cl
Ru
PPh2Py
2
N
H
P
2
Cl
complex 8
PDA = 1,2-phenylenediamine
Complex 2
Complex 5
complex 9
Scheme 1.
Scheme 3.

P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
3121
the complexes show broad peaks around 4.5–5.0 ppm
due to the coordinated NH2 group. The structure of
complex 2 is shown in Fig. 2.
ene complex 11 is confirmed by the appearance of the
m(C@C@C) absorption mode (asymmetric stretching
1
vibration) as a strong band at 1964 cmꢀ1 [20]. The H
The electronic spectrum of complex 2 in dichloro-
methane features a UV–vis pattern similar to the analo-
gous ruthenium polypyridyl complexes [18], which arises
from the metal-to-ligand charge transfer at 393 nm.
NMR spectrum of complex 10 shows a singlet for the
acetonitrile methyl protons at 2.18 ppm. The phenyl
protons appear in the aromatic region in the range of
7.15–8.95 ppm for both complexes. HMB protons are
observed at 2.06 ppm for complex 10 and at 1.83 ppm
for complex 11. The 31P {1H} NMR spectrum of com-
plexes exhibits a sharp peak at 13.57 ppm for complex
10 and at 15.32 ppm for complex 11.
4.2. Complexes of diphenyl-2-pyridylphosphine (8–11)
The reaction of [{(g6-C6Me6)Ru(l-Cl)Cl}2] (7) with
diphenyl(2-pyridyl)phosphine in dichloromethane yields
the neutral P-coordinated complex 8. However, in meth-
anol, the P,N-chelated cationic complex [(g6-C6Me6)R-
u(PPh2Py)Cl]+ (9) is isolated as the tetrafluoroborate
salt 9[BF4]. Complex 8 with an excess of NH4BF4 in
methanol gives the complex 9[BF4] (Scheme 3). These
complexes are stable in air and soluble in polar solvents
such as chloroform and dichloromethane, but are insol-
uble in non-polar solvents such as hexane and pentane.
The spectroscopic data clearly suggests the coordina-
tion of the ligand to the metal as evident from the shift
of the phosphorus and proton resonance compared to
(BF )
4 2
BF
4
MeCN, 2 h.
NH4BF4
N
Ru
NCCH
Ru
3
P
Cl
N
P
complex 9
complex 10
ð2Þ
BF
4
(BF )
4 2
1
Ph
Ph
the starting complex 7. The H NMR spectrum of com-
HC
C C(OH)Ph
2
N
Ru
Ru
=C=C=C
plex 8 shows a singlet at 1.76 ppm for the hexamethyl-
benzene protons (an upfield shift compared to the
starting compound) and also in the aromatic region at
7.13–8.11 ppm for the phosphine ligand. The 31P
NMR shows one singlet at 25.88 ppm for the phosphine
ligand, where a significant downfield shift is observed
after coordination to the metal as compared to the free
ligand (ꢀ3.43 ppm). The far IR spectrum shows a strong
band at 286 cmꢀ1 for the Ru–Cl stretching vibration
mode.
MeOH, 3 h.
NH4BF4
P
Cl
N
P
complex 9
complex 11
ð3Þ
5. Molecular structures
The 1H NMR spectrum of complex 9 shows a pattern
of signals different from the spectrum of complex 8. The
pyridine ring protons appear as two triplets at 7.89 and
8.01 ppm and one doublet at 8.67 ppm. The phenyl
group protons appear as a multiplet in the aromatic re-
gion at 7.09–7.79 ppm. The singlet at 2.08 ppm for the
hexamethyl-benzene protons indicates a downfield shift
compared to complex 8. The 31P {1H} NMR spectrum
of complex 9 exhibits a singlet at ꢀ11.25 ppm (upfield
compared to complex 8). The far IR spectrum shows a
band at 280 cmꢀ1, which is assigned to the terminal
stretching vibration of mRu–Cl. In addition, the IR spec-
trum contains a strong band at 1089 cmꢀ1 due to the
mB–F mode of the BF4 group. However, we do not ob-
serve formation of a pyridylphosphine-coordinated
complex of the type [Ru(PPh2Py)2Cl2] in these reactions,
as was the case for the p-cymene ruthenium dimer [19].
Treatment of the complex [(g6-C6Me6)Ru(PPh2-
Py)Cl]BF4 (9) with acetonitrile and 1,1-diphenyl-2-pro-
pyn-1-ol ligands generated the cationic complexes 10
and 11 (reactions (2) and (3)), which can be isolated in
good yield as their BF4 salts. Formation of the allenylid-
In order to confirm the structures suggested by the
spectroscopic data, molecular structures of complexes
2, 8 and 9 were determined using single-crystal X-ray
diffraction studies. The summary of the single-crystal
X-ray structure analyses is shown in Table 1. ORTEP
drawings of the complexes 2, 8 and 9 are shown in Figs.
2–4, respectively.
The structure of complex 2 consists of a ruthenium
atom g6-coordinated to a p-cymene molecule, two chlo-
rine atoms and one benzylamine ligand (through the N
atom) leading to the usual ꢀthree-legged piano stoolꢁ
structure. The complex [(g6-p-cymene)Ru(NH2CH2-
C6H5)Cl2] (2) crystallizes in the monoclinic space group
P21/c (Fig. 2). The average Ru–C bond distance is
˚
2.1726 A, whereas the distance between the ruthenium
˚
atom and the centroid of the ring is 1.670 A at the axis
x = 0.3938, y = 0.3638 and z = 0.1334. These bond
lengths are closely related to those in other reported
complexes [21]. The Ru–N bond length involving ben-
˚
zylamine is 2.1445(18) A, which is within the usual range
of Ru–N bond distances [22]. The Ru–Cl bond lengths
˚
are 2.4282(6) and 2.4297(6) A, well in accord with the

3122
P. Govindaswamy et al. / Polyhedron 23 (2004) 3115–3123
literature values [23]. The geometry of the complex is
octahedral with a piano-stool structure and is marked
by the nearly 90ꢁ value for the bond angles between
the non-p-cymene ligands at the metal centre, viz.,
Cl(1)–Ru–Cl(2) (87.66(2)ꢁ), N–Ru–Cl(1) (80.97(6)ꢁ)
and N–Ru–Cl(2) (80.65(5)ꢁ).
Complex 8 crystallizes in the monoclinic space group
C2/c. The geometry around the ruthenium atom in com-
plex 8 is octahedral where the hexamethylbenzene occu-
pies three-coordination positions. Complex 8 also has a
ꢀthree-legged piano stoolꢁ type structure. Fig. 3 shows an
ORTEP representation of complex 8. The Ru–Cl(1) and
[RuCl2(PPh2Py)2] [19]. The hexamethylbenzene ruthe-
nium(II) dimer [(g6-C6Me6)RuCl2]2 under the same
conditions gave only one product having an organic
fragment, viz., [(g6-C6Me6)Ru(PPh2Py)Cl]BF4. This is
a clear indication that hexamethylbenzene binds to
the metal quite strongly for the latter case due to the
high electron-donating ability of the g6-C6Me6 moiety
relative to the g6-p-cymene in these ruthenium
complexes.
Acknowledgements
˚
Ru–Cl(2) bond distances (2.417(2) and 2.422(2) A) are
˚
closely related to other reported values (2.4299 A) [24].
˚
The Ru–P bond distance 2.3573(19) A is within the
range of the literature values [24a]. The average bond
distance between ruthenium and hexamethylbenzene is
K.M.R. and P.G. thank the Sophisticated Instru-
ments Facility (SIF), Indian Institute of Science, Banga-
lore, for providing the NMR facility. We thank Prof.
R.H. Duncan Lyngdoh for help in preparing the
manuscript.
˚
2.227 A, and the distance between ruthenium and the
˚
centroid of the ring is 1.740 A. The bond angles P–
Ru–Cl(1), P–Ru–Cl(2) and Cl(1)–Ru–Cl(2) are
88.51(7)ꢁ, 88.20(7)ꢁ and 86.41(8)ꢁ, respectively, indicat-
ing a piano stool type structure.
Appendix A. Supplementary data
Crystallographic data for the structural analyses have
been deposited at the Cambridge Crystallographic Data
Centre (CCDC), CCDC No. 246203 for complex 2,
CCDC No. 246204 for complex 8, and CCDC No.
246205 for complex 9. Copies of this information may
be obtained free of charge from The Director, CCDC,
12 Union Road, Cambridge, CB2 1EZ, UK (fax: +44
1223 336 033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk). Supplementary data
associated with this article can be found, in the online
version at doi:10.1016/j.poly.2004.09.031.
Complex 9 crystallizes with onꢀe molecule of acetone;
the complex cation and the BF4 anion are joined by
coulombic forces. Complex 9 contain a ruthenium atom
g6-coordinated to
a hexamethylbenzene ring and
bonded to a chlorine atom and a bidentate PPh2Py lig-
and through the P and N atoms. Fig. 4 is an ORTEP
representation of complex 9. Complex 9 crystallizes in
the monoclinic space group P21. The Ru–P bond dis-
˚
tance 2.3412(13) A is shorter than in complex 8. This
is because the diphenyl(2-pyridyl)phosphine ligand re-
stricts the bite angle of the four-membered chelating ring
using both the P and N atoms. The Ru–Cl and Ru–
˚
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