Syntheses and characterization of η6- hexamethylbenzeneruthenium(II)-β-diketone complexes: Their reactions with mono- and bidentate neutral ligands

Article abstract of DOI:10.1016/j.jorganchem.2004.11.036

The complex [(η⁶-C₆Me₆)Ru(μ-Cl)Cl] ₂ 1 react with sodium salts of β-diketonato ligands in methanol to afford the oxygen bonded neutral complexes of the type [(η⁶- C₆Me₆)Ru(κ²-O,O′-R ¹COCHCOR²)Cl] {R¹, R² = CH ₃ (2), CH₃, C₆H₅ (3), C ₆H₅ (4), OCH₃ (5), OC₂H₅ (6)}. Complex 4 with AgBF₄ yields the γ-carbon bonded ruthenium dimeric complex 7. Complex 4 also reacts with tertiary phosphines and bridging ligands to yield complexes of the type [(η⁶-C₆Me ₆)Ru(κ²-O,O′-C₆H ₅COCHCOC₆H₅)(L)]⁺ (L = PPh ₃ (8), PMe₂Ph (9)) and [{η⁶-C ₆Me₆)Ru(κ²-O,O′-C₆H ₅COCHCOC₆H₅)}₂(μ-L)] L = 4,4′-bipyridine (4,4′-bipy) (11), 1,4-dicyanobenzene (DCB) (12) and pyrazine (Pz) (13). Complexes 2-4 react with sodium azide to yield neutral complexes [(η⁶-C₆Me₆) Ru(κ²-O,O′-R¹COCHCOR²)N ₃] {R¹, R² = CH₃ (10a), CH ₃, C₆H₅ (10b), C₆H₅ (10c). All these complexes were characterized by FT-IR and FT-NMR spectroscopy as well as analytical data. The molecular structures of complexes [(η⁶-C₆Me₆)Ru(κ²-O, O′CH₃COCH-COC₆H₅)Cl] (3) and [(η⁶-C₆Me₆)Ru(κ²-O, O′-C₆H₅COCHCOC₆H₅] (4) were established by single crystal X-ray diffraction studies. The complex 3 crystallizes in the triclinic space group, P1? [a = 7.9517(4), b = 9.0582(4) and c = 14.2373(8) A?, α = 88.442(3)°, β = 76.6.8(3)° and γ = 81.715(3)°. V = 987.17(9) A?³, Z = 2]. Complex 4 crystallizes in the monoclinic space group, P2₁/c [a = 7.5894(8), b = 20.708(2) and c = 29.208(3) A?,β = 92.059(3)° V = 4587.5(9) A?³, Z = 8].

Full text of DOI:10.1016/j.jorganchem.2004.11.036

Journal of Organometallic Chemistry 690 (2005) 1218–1225
www.elsevier.com/locate/jorganchem
Syntheses and characterization of
g6-hexamethylbenzeneruthenium(II)-b-diketone complexes:
their reactions with mono- and bidentate neutral ligands
a
P. Govindaswamy , Shaikh M. Mobin , Carsten Thone , Mohan Rao Kollipara
¨
b
c
a,
*
a
Department of Chemistry, North Eastern Hill University, Shillong 793022, India
National Single Crystal X-ray Diffraction Laboratory, Indian Institute of Technology, Bombay 400 076, India
b
c
Institut fu¨r Anorganische und Analytische Chemieder TU, Hagenring 30, 38106 Braunschweig, Germany
Received 23 September 2004; accepted 15 November 2004
Abstract
The complex [(g6-C6Me6)Ru(l-Cl)Cl]2 1 react with sodium salts of b-diketonato ligands in methanol to afford the oxygen bonded
neutral complexes of the type [(g6-C6Me6)Ru(j2-O,O0-R1COCHCOR2)Cl] {R1, R2 = CH3 (2), CH3, C6H5 (3), C6H5 (4), OCH3 (5),
OC2H5 (6)}. Complex 4 with AgBF4 yields the c-carbon bonded ruthenium dimeric complex 7. Complex 4 also reacts with tertiary
phosphines and bridging ligands to yield complexes of the type [(g6-C6Me6)Ru(j2-O,O0-C6H5COCHCOC6H5)(L)]+ (L = PPh3 (8),
PMe2Ph (9)) and [{g6-C6Me6)Ru(j2-O,O0-C6H5COCHCOC6H5)}2(l-L)] L = 4,40-bipyridine (4,40-bipy) (11), 1,4-dicyanobenzene
(DCB) (12) and pyrazine (Pz) (13). Complexes 2–4 react with sodium azide to yield neutral complexes [(g6-C6Me6)Ru(j2-O,O0-
R1COCHCOR2)N3] {R1, R2 = CH3 (10a), CH3, C6H5 (10b), C6H5 (10c). All these complexes were characterized by FT-IR and
FT-NMR spectroscopy as well as analytical data. The molecular structures of complexes [(g6-C6Me6)Ru(j2-O,O0CH3COCH–
COC6H5)Cl] (3) and [(g6-C6Me6)Ru(j2-O,O0-C6H5COCHCOC6H5] (4) were established by single crystal X-ray diffraction studies.
˚
ꢀ
The complex 3 crystallizes in the triclinic space group, P1 [a = 7.9517(4), b = 9.0582(4) and c = 14.2373(8) A, a = 88.442(3)ꢀ,
3
˚
b = 76.6.8(3)ꢀ and c = 81.715(3)ꢀ. V = 987.17(9) A , Z = 2]. Complex 4 crystallizes in the monoclinic space group, P21/c
3
˚
˚
[a = 7.5894(8), b = 20.708(2) and c = 29.208(3) A,b = 92.059(3)ꢀ V = 4587.5(9) A , Z = 8].
ꢁ 2004 Elsevier B.V. All rights reserved.
Keywords: Hexamethylbenzene; b-diketones; Phosphines; Azide; Bridging ligands; Ruthenium
1. Introduction
the first half-sandwich arene ruthenium(II)-enzyme
complex which was isolated by the reaction of g6-p-cym-
ene ruthenium(II) complex with hen egg-white lysozyme
[5]. The reactivity of areneruthenium(II) dimers with
various ligands has been reported [6]. Only very few re-
ports of the chemistry of areneruthenium(II) complexes
containing O,O0-donor ligands are available, mainly
examples concerned with acetylacetonato [7] and carb-
oxylato complexes [8].
The chemistry of half-sandwich g6-arene-ruthenium
complexes has been widely developed in the past decade,
in part due to their catalytic potential, but also due to
their usefulness in the synthesis of other Ru(0) and
Ru(II) complexes [1–4]. Recently, McNae et al. reported
*
Corresponding author. Tel.: +91 364 272 2620; fax: +91 364 255
In 1979, Rigby et al. [9] reported the complex [(g5-C5-
Me5)RhCl(acac)] obtained from the [(g5-C5Me5)RhCl2]2
dimer with acetylacetonate salt. It was found that
0076.
E-mail addresses: kmrao@nehu.ac.in, mrkollipara@yahoo.com
(M.R. Kollipara).
0022-328X/$ - see front matter ꢁ 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.11.036

P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
1219
acetylacetonate (acac) is bound in the usual way as a
monoanionic bidentate O,O0-ligand. In the case of p-
cymene ruthenium dimer only few example was avail-
able with acac reported by Oro and coworkers [10]
and Bennett et al. [11]. Both were reported as p-cymene
ruthenium acac complexes although structural charac-
terization has not yet been carried out. Herein, we would
like to report the synthesis of b-diketonato complexes of
[(g6-C6Me6)RuCl2]2 dimer, and their reactions with neu-
tral ligands such as PPh3, PMe2Ph, 4,40-bipy, DCB and
Pz. The representative complexes 3 and 4 were charac-
terized by single crystal X-ray analyses.
2 Yield: 68 mg, (53%). IR (KBr pellets, cmꢀ1): mC@O
1580s, mC@C 1520s. 1H NMR (CDCl3, d): 2.01 (s,
6H, CH3), 2.07 (s, 18H, HMB), 5.10 (s, 1H, CH).
Elemental analysis (%) for C17H25O2ClRu: Calcu-
lated – C 51.49, H 6.33; found – C 51.36, H 6.41.
3 Yield: 80 mg, (53%). IR (KBr pellets, cmꢀ1): mC@O
1560s, mC@C 1520s. 1H NMR (CDCl3, d): 2.12 (s,
18H, HMB), 2.15 (s, 3H, CH3), 5.78 (s, 1H, CH),
7.34–7.42 (m, 3H, Ph), 7.89 (d, 2H, JH–H 7.16 Hz,
Ph).
Elemental analysis (%) for C22H27O2ClRu: Calcu-
lated – C 57.47, H 5.87; found – C 57.63, H 5.24.
4 Yield: 105 mg, (62%). IR (KBr pellets, cmꢀ1): mC@O
1593s, mC@C 1533s. 1H NMR (CDCl3, d): 2.18 (s,
18H, HMB), 6.47 (s, 1H, CH), 7.39–7.48(m, 6H,
Ph), 7.99 (d, 4H, JH–H 7.00 Hz, Ph).
2. Experimental
2.1. General considerations
Elemental analysis (%) for C27H29O2ClRu: Calcu-
lated – C 62.14, H 5.55; found – C 62.31, H 5.96.
Solvents obtained from commercial sources were
distilled prior to use. Ketones, triphenylphosphine
(Merck), PMe2Ph, 4,40-bipyridine, 1,4-dicyanobenzene,
pyrazine (Aldrich), hexamethylbenzene (Acros Organ-
ics) and ruthenium trichloride trihydrate purchased
from Arora Matthey Ltd, were used as supplied.
Infrared spectra of b-diketones and their ruthenium
(II) complexes (KBr, pellets) were recorded in the
4000–400 cmꢀ1 range using a Perkin–Elmer-model
983 spectrophotometer. The NMR spectra were taken
on Bruker-AMX-400 (400 MHz) and Bruker-ACF-300
(300 MHz) spectrometers with tetramethylsilane as an
internal standard. 31P {1H} NMR chemical shifts were
reported relative to H3PO4 (85%). Elemental analyses
were performed in a Perkin–Elmer-2400 CHN/O ana-
lyzer. The precursor complex [(g6-C6Me6)Ru(l-Cl)Cl]2
1 was prepared according to the literature method
[12].
2.2.2. Syntheses of b-dicarbonyl complexes
[(g6-C6Me6)Ru(j2-O,O0-R1COCHCOR2)Cl] (5–6)
{R1, R2 = OCH3 (5), OC2H5 (6)}
These two complexes were prepared by using the
above method except sodium salt of dialkyl malonates
used in place of sodium salt of b-diketonato ligand.
5 Yield: 72 mg, (52%). IR (KBr pellets, cmꢀ1): mC@O
1593s, mC@C 1514s. 1H NMR (CDCl3, d): 2.03 (s,
18H, HMB), 3.74 (s, 6H, CH3), 5.09 (s, 1H, CH).
Elemental analysis (%) for C17H25O4ClRu: Calcu-
lated – C 47.49, H 5.86; found – C 47.03, H 5.98.
6 Yield: 78 mg, (53%). IR (KBr pellets, cmꢀ1): mC@O
1593s, mC@C 1520s. 1H NMR (CDCl3, d): 1.99 (t,
6H, JH–H 5.12 Hz, CH3), 2.00 (s, 18H, HMB), 3.13
(b, 4H, CH2), 5.10 (s, 1H, CH).
Elemental analysis (%) for C19H29O4ClRu: Calcu-
lated – C 49.85, H 6.33; found – C 49.36, H 6.53.
2.2. Syntheses of b-diketonato and b-dicarbonyl
complexes
2.2.1. Syntheses of [(g6-C6Me6)Ru(j2-O,O0-
R1COCHCOR2)Cl] (2–6) {R1, R2 = CH3 (2) [11],
CH3, C6H5 (3), C6H5 (4)}
2.3. Synthesis of [(g6-C6Me6)2Ru2(j2-O,O0-
C6H5COCHCOC6H5)2](BF4)2 (7)
The following general procedure was used for the
syntheses of these three complexes.
A suspension of complex 4 (60 mg, 0.115 mmol) and
AgBF4 (44 mg, 0.229 mmol) in dichloromethane (15 ml)
was stirred for 1 h. A white solid was precipitated which
was filtered off. The solution was concentrated to 2 ml
and an addition of excess hexane gave the yellow
complex.
A mixture of the starting complex [(g6-C6Me6)Ru(l-
Cl)Cl]2 1 (100 mg, 0.149 mmol) and the appropriate
sodium salt of b-diketonato ligand (0.448 mmol) in
methanol (20 ml) were stirred for 3 h while the color
of the solution changed red to orange. The solvent was
removed in vacuo, the residue dissolved in dichlorome-
thane (5 ml), and the solution filtered to remove sodium
chloride. The orange solution was concentrated (2 ml)
and an addition of excess hexane gave the orange-
yellow complex, which was separated and dried under
vacuum.
Yield: 83 mg, (63%). IR (KBr pellets, cmꢀ1): mC@O
1593s, mC@C 1527s, mB–F 1089s.
1H NMR (CDCl3, d): 2.18 (s, 36H, HMB), 5.58 (s,
2H, CH), 7.26–7.47 (m, 12H, Ph), 7.93 (d, 8H, JH–H
6.95 Hz, Ph).
Elemental analysis (%) for C54H58Ru2O4B2F8: Calcu-
lated – C 56.55, H 5.09; found – C 56.64, H 4.97.

1220
P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
2.4. Syntheses of [(g6-C6Me6)Ru(j2-O,O0-
C6H5COCHCOC6H5)(L)](BF4) {L = PPh3 (8),
PMe2Ph (9)} complexes
Elemental analysis (%) for C17H25RuN3O2: Calcu-
lated – C 50.48, H 6.22, N 10.38; found – C
50.15, H 6.37, N 10.01.
10b Yield: 48 mg, (59%). IR (KBr pellets, cmꢀ1): mC@O
1576s, mC@C 1513s, mN3 2026s (terminal).
1H NMR (CDCl3, d): 2.12 (s, 18H, HMB), 2.14 (s,
3H, CH3), 5.63 (s, 1H, CH), 7.32–7.38 (m, 3H, Ph),
7.79 (d, 2H, Ph).
The following general procedure was used for prepar-
ing these two complexes.
A mixture of complex 4 (60 mg, 0.115 mmol), the
phosphine ligand (0.344 mmol) and NH4BF4 (36 mg,
0.344 mmol) was stirred in acetone (15 ml) for 6 h,
and the solvent was rotary evaporated. The residue
was dissolved in dichloromethane and filtered through
a short silica gel column to remove the insoluble
material. The filtrate was concentrated to about 2
ml, whereupon addition of excess hexane gave the de-
sired complexes (8 and 9) as yellow solids. The solid
was washed with diethyl ether and dried under
vacuum.
Elemental analysis (%) for C22H27RuN3O2: Calcu-
lated – C 56.63, H 5.83, N 9.00; found – C 56.42,
H 5.63, N 8.91.
10c Yield: 53 mg, (57%). IR (KBr pellets, cmꢀ1): mC@O
1
1593s, mC@C 1533s mN3 2037s (terminal). H NMR
(CDCl3, d): 2.19 (s, 18H, HMB), 6.42 (s, 1H,
CH), 7.40–8.02 (m, 10H, Ph).
Elemental analysis (%) for C27H29RuN3O2: Calcu-
lated – C 61.34, H 5.52, N 7.94; found – C 61.06,
H 5.32, N 8.03.
8 Yield: 71 mg, (75%). IR (KBr pellets, cmꢀ1): mC@O
1593s, mC@C 1533s, mB–F 1089s. 1H NMR (CDCl3,
d): 1.83 (s, 18H, HMB), 6.04 (s, 1H, CH), 7.28–7.63
(m, 15H, Ph), 7.68 (d, 10H, JH–H 7.48 Hz, Ph). 31P
{1H} NMR (CDCl3, d): 32.46 (s).
Elemental analysis (%) for C45H44O2PRuBF4: Calcu-
lated – C 64.67, H 5.30; found – C 64.58, H 5.15.
9 Yield: 60 mg, (74%). IR (KBr pellets, cmꢀ1): mC@O
1593s, mC@C 1527s, mB–F 1089s. 1H NMR (CDCl3,
d): 1.82 (s, 6H, CH3), 1.89 (s, 18H, HMB), 5.30 (s,
1H, CH), 7.42–7.59 (m, 9H, Ph), 7.75 (d, 2H, JH–H
7.37 Hz, Ph), 7.96 (d, 4H, JH–H 7.15 Hz, Ph). 31P
{1H} NMR (CDCl3, d): 29.75 (s).
Method 2: The above mentioned complexes 10a–c
can be prepared by the reaction of the dimeric com-
plex [{g6-C6Me6)Ru(l-N3)Cl}2] [12c] (100 mg, 0.146
mmol) with sodium salt of corresponding b-diketo-
nates (0.367 mmol) were stirred in acetone for 3 h at
room temperature, while the orange colored suspen-
sion gradually changed to a yellow solution. The solu-
tion was concentrated under reduced pressure. The
solid was dissolved in dichloromethane and then fil-
tered to remove sodium chloride. The solution was
concentrated for 2 ml and an excess of hexane added
for precipitation. The yellow colored product was sep-
arated out, washed with diethyl ether and dried under
vacuum. Yield: 55–60%.
Elemental analysis (%) for C35H40O2PRuBF4: Calcu-
lated – C 59.08, H 5.66; found – C 59.24, H 5.38.
2.6. Syntheses of [(g6-C6Me6)Ru(j2-O,O0-
C6H5COCHCOC6H5)2(l-L)](BF4)2 {L = 4,40-bipy
(11), DCB (12), pz (13)} complexes
2.5. Syntheses of [(g6-C6Me6)Ru(j2-O,O0-
R1COCHCOR2)(N3)] {R1, R2 = CH3 (10a), CH3,
C6H5 (10b), C6H5 (10c)} complexes
The following general procedure was used for prepa-
ration of these three complexes.
The following general procedure was used for prepar-
ing these three complexes.
A mixture of complex 4 (60 mg, 0.115 mmol), ligand
L (0.115 mmol) and AgBF4 (89 mg, 0.46 mmol) were
stirred in acetone (15 ml) for 1 h. A white solid was pre-
cipitated which was filtered off and the solution was ro-
tary evaporated. The residue was dissolved in
dichloromethane and filtered through short silica gel
column to remove insoluble material. The filtrate was
concentrated to about 2 ml and an addition of excess
hexane gave the yellow product, which was separated
and dried under vacuum.
Method 1: A mixture of complexes (2–4) (0.115
mmol) and sodium azide (0.23 mmol) were stirred in
dry acetone for 3 h at room temperature, when the or-
ange colored suspension gradually changed to a yellow
solution. The solution was concentrated under reduced
pressure. The solid was dissolved in dichloromethane
and then filtered. The solution was concentrated for 2
ml and an excess of hexane added for precipitation.
The yellow colored product was separated out, washed
with diethyl ether and dried under vacuum.
11 Yield: 71 mg, (47%). IR (KBr pellets, cmꢀ1): mC@O
1
10a Yield: 45 mg, (63%). IR (KBr pellets, cmꢀ1): mC@O
1586s, mC@C 1515s, mN3 2024s (terminal).
1H NMR (CDCl3, d): 2.01 (s, 6H, CH3), 2.04 (s,
18H, HMB), 5.08 (s, 1H, CH).
1593s, mC@C 1526s, mB–F 1075s. H NMR (CDCl3,
d): 2.08 (s, 36H, HMB), 6.27 (s, 2H, CH), 7.44–
7.50 (m, 12H, Ph), 7.68–7.89 (m, 8H, Ph), 7.97 (d,
4H, JH–H 5.90 Hz), 8.59 (d, 4H, JH–H 5.68 Hz).

P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
1221
Elemental analysis (%) for C64H66O4N2Ru2B2F8:
Calculated – C 58.99, H 5.10, N 2.15; found – C
58.84, H 5.17, N 2.23.
Ph
(BF )
4 2
O
12 Yield: 62 mg, (43%). IR (KBr pellets, cmꢀ1): mC@O
Ru
1
1593s, mC@C 1533s, mB–F 1076s. H NMR (DMSO-
d6, d): 2.13 (s, 36H, HMB), 5.95 (s, 2H, CH), 6.55
(d, 2H, JH–H 4.86 Hz, DCB), 7.12 (d, 2H, JH–H
4.83 Hz, DCB), 7.50–7.96 (m, 12H, Ph), 8.20 (d,
8H, JH–H 7.72 Hz, Ph).
O
Ph
Ph
O
Ru
Elemental analysis (%) for C62H62O4N2Ru2B2F8:
Calculated – C 58.41, H 4.90, N 2.19; found – C
58.16, H 5.03, N 2.13.
O
Ph
13 Yield: 63 mg, (45%). IR (KBr pellets, cmꢀ1): mC@O
Fig. 1. Complex 7.
1
1593s, mC@C 1527s, mB–F 1082s. H NMR (CDCl3,
d): 2.07 (s, 36H, HMB), 6.04 (s, 2H, CH), 7.34–
7.72 (m, 20H, Ph), 7.78 (d, 2H, JH–H 7.19 Hz),
8.82 (d, 2H, 6.78 Hz).
Elemental analysis (%) for C58H62O4N2Ru2B2F8:
Calculated – C 56.53, H 5.09, N 2.28; found – C
56.34, H 5.16, N 2.32.
3. Crystallographic investigations
Crystal structure determinations of complexes 3 and
4 were performed on a Bruker SMART 1000 CCD area
detector (graphite monochromated Mo Ka radiation,
k = 71.073 pm) at ꢀ140 ꢀC in the x- and /-scan mode.
Cell parameters were refined from 7955 number of
reflections in the h-range of 2.31–30.43 for 4, and from
15,403 number of reflections in the h-range of 2.27–
30.49 for 3. Empirical absorption corrections were ap-
plied using the program SADABS [13]. The structures
were solved by direct methods using SHELXS-86/97
[14], and subjected to full-matrix least-squares refine-
ment on F2 using SHELXL-93/97 [15], with anisotropic
displacement parameters for non-H atoms. Methyls
were treated as rigid groups. All other hydrogen atoms
were included using a riding model. Figs. 1 and 2 are
the ORTEP [16] representations of the molecules with
50% probability thermal ellipsoids displayed. Refine-
ment converged at a final R1 value of 0.0238 for complex
3 and 0.0410 for complex 4 (for observed data F), and
wR2 values of 0.0617 and 0.0826 for complex 3 and 4,
respectively (for unique data F2).
Fig. 2. ORTEP diagram of the complex 3 with 50% probability
thermal ellipsoids.
air-stable microcrystalline solids, soluble in chloroform
and dichloromethane and partially soluble in benzene
or diethylether. These complexes were characterized on
1
the basis of elemental analysis and H NMR and IR
spectroscopy. The IR spectra show the presence of two
m(CO) bands in the range 1560–1593 cmꢀ1 and m(C@C)
bands in the range 1514–1533 cmꢀ1 [17–19]. The 1H
NMR spectra of these complexes exhibit a strong peak
at 2.00–2.12 ppm for hexamethylbenzene, which is
slightly shifted downfield in comparison to the starting
complex 1, which exhibits it at 2.02 ppm. Resonance
of the C–H proton of the b-diketonato ligands is ob-
served as a singlet in the range 5.10–6.47 ppm in these
complexes.
4. Results and discussion
4.1. b-Diketonato and b-dicarbonyl complexes
The b-diketonato ruthenium(II) complexes 2–4 un-
dergo substitution reactions with excess of sodium azide
in acetone, giving the neutral complexes (10a–c) (Fig. 1).
The infrared spectra of the complexes 10a–c show a
strong band around 2037 cmꢀ1 due to the terminal azide
group [12c,20] along with other strong bands due to the
The reaction of [(g6-C6Me6)Ru(l-Cl)Cl]2 1 with so-
dium salts of b-diketonates in methanol at room temper-
ature results in the cleavage of the halide bridges of the
starting dimer (Fig. 1). The orange-yellow complexes are

1222
P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
Cl
Cl
-diketonates
β
R1, R2 = CH3 (2)
Ru
Ru
Cl
Cl
Ru
O
= CH3, C6H5 (3)
= C6H5 4)
= OCH3 (5)
= OC2H5 (6)
MeOH, 3 h
O
Cl
1
R
complex 1
2
R
acetone, 3h
NaN
NH BF
4
4
L, acetone
3
Ru
N
3
BF
O
O
4
L
Ru
O
O
R
'
R
Ph
Ph
L = PPh (8)
R, R' = CH (10a)
3
3
R, R' = CH , C H (10b)
3
6 5
L = PMe Ph (9)
2
R, R' = C H (10c)
6
5
Scheme 1.
m
(CO) and m(C@C) groups of the b-diketonato ligands. The
1H NMR spectrum of the complex shows a singlet at
2.18 ppm for HMB, and a multiplet for the phenyl
groups in the region at 7.26–7.93 ppm.
1H NMR spectra of these complexes exhibit a strong
peak for hexamethylbenzene at 2.04–2.19 ppm.
Treatment of the complex [(g6-C6Me6)Ru(j2-O,O0-
C6H5COCHCOC6H5)Cl] 4 with phosphine ligands gen-
erates the cationic complexes 8 and 9 (Fig. 1), which can
be isolated in good yield as their BF4 salts. The forma-
tion of the cationic complexes 8 and 9 is confirmed by
the appearance of the mCO absorption band at 1593
cmꢀ1 and m(B–F) absorption as a strong band at 1089
4.2. Cationic complexes
The complex 7 was obtained when the b-diketonato
complex 4 was treated with AgBF4 in dichloromethane.
The IR spectra show a strong m(CO) band at 1593 cmꢀ1
and a m(C@C) band at 1527 cmꢀ1. In addition, a strong
band appears at 1089 cmꢀ1 due to the m(B–F) mode of
1
cmꢀ1. The H NMR spectrum of the complexes shows
1
the BF4 group. The elemental analysis and H NMR
a singlet for the hexamethylbenzene protons at 1.83
and 1.89 ppm, while the phenyl protons appear in the
aromatic region in the range of 7.28–7.96 ppm for both
the complexes. The methine (C–H) proton is observed at
6.04 ppm for complex 8 and 5.30 ppm for complex 9.
The 31P {1H} NMR spectra of these complexes exhibit
a sharp peak at 32.46 ppm for complex 8 and 29.75
ppm for complex 9.
spectra suggest that the complex 7 is binuclear (Fig. 1)
containing a bridging (j2-O,O0,C–C6H5COCHCOC6H5)
group.
This type of bonding (Fig. 1) was also observed in the
case of b-diketonato complexes of Cp*Rh [9] and p-
cymene osmium [11], where the c-carbon proton is re-
moved and a metal–carbon bond is formed [21]. The
(BF )
4 2
Ph
Ph
O
O
L, acetone
Ru
Cl
Ru
L
Ru
NH BF
4
4
O
O
O
O
Ph
Ph
Complex 4
Ph
Ph
L = 4,4'-bypyridine (11)
L = 1,4-dicyanobenzene (12)
L = pyrazine (13)
Scheme 2.

P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
1223
Table 1
Crystal data and structure refinement parameters for complexes 3 and
4.3. Binuclear bridging complexes
4
The reaction of the complex 4 with bridging
nitrogen donor ligands in presence of silver tetrafluo-
roborate in acetone resulted in the formation of yel-
low-colored and air-stable binuclear complexes 11–13
(Fig. 2), respectively. The formation of these com-
plexes is confirmed by their 1H NMR spectra. The
IR spectra of these complexes show a strong band
in the range 1075–1082 cmꢀ1 due to the m(B–F) mode
of the BF4 group. The 1H NMR spectra of these
complexes exhibit a strong peak for hexamethylben-
zene protons as a singlet in the range 2.07–2.13
ppm. The aromatic protons of the ligand L appear
as multiplets around 6.55–8.50 ppm for these com-
plexes. The singlet in the range 5.95–6.27 ppm is ob-
served due to the C–H proton of the b-diketonato
ligands.
3
4
Formula
Mr
T (K)
C22H27ClO2Ru
459.96
133 (2)
C27H29ClO2Ru
522.02
133 (2)
0.71073
Monoclinic
P21/c
˚
Wavelength (A)
Crystal system
Space group
0.71073
Triclinic
ꢀ
P1
˚
a (A)
7.9517(4)
9.0582(4)
14.2373(8)
88.442(3)
76.608(3)
81.715(3)
987.17(2)
2
7.5894(8)
20.708(2)
29.208(3)
90
˚
b (A)
˚
c (A)
a (ꢀ)
b (ꢀ)
c (ꢀ)
92.059(3)
90
3
˚
V (A )
4587.5(9)
8
Z
Crystal size (mm3)
Dcalc (g cmꢀ3)
F(0 0 0)
0.27 · 0.25 · 0.16 0.18 · 0.17 · 0.12
1.547
472
1.512
2144
h (ꢀ)
1.47–30.03.
21,112
1.40–28.00
83,882
Reflections collected
Independent reflections (Rint
Completeness to h
Data/parameters
Goodness-of-fit on F2
R1 [I > 2r(I)], wR2
R1, R2 (all data)
Largest differential peak
)
5748 (0.0198)
30.00ꢀ – 999.5%
5748/0/242
1.025
11,040 (0.0887)
28.00ꢀ – 100.0%
11,040/0/571
1.037
5. Molecular structures
Single-crystal X-ray structure determinations were
carried out for complexes 3 and 4 for confirmation of
the formulation. Crystals 3 and 4 were grown by slow
diffusion of hexane into dichloromethane solution of
the complexes. The ruthenium atom is coordinated to
two oxygen atoms of the b-diketonato ligand, one chlo-
ride ligand and the hexamethylbenzene molecule in g6-
fashion leading to the usual Ôthree-legged piano stoolÕ
structures. The geometry around the metal atom can
be regarded as distorted octahedral if the g6-hexameth-
ylbenzene moieties are assumed to occupy three
facial-coordinated positions. The summary of the sin-
gle-crystal X-ray structure analyses is shown in Table
1. Selected bond lengths and bond angles are given in
Tables 2 and 3. The ORTEP drawings of complexes 3
and 4 are shown in Figs. 2 and 3, respectively.
0.0238, 0.0617
0.0261, 0.0632
0.0410, 0.0826
0.0791, 0.0975
1.488 and ꢀ0.481 0.784 and ꢀ0.563
ꢀ3
˚
and hole (e A
)
tween the ruthenium atom and the centroid of ring is
˚
˚
1.648 (1) A in complex 3 whereas 1.653 (1) A in complex
4, respectively. These bond lengths are closely related to
those in other reported complexes [22]. The Ru–O bond
lengths involving in bonding to the -diketonates are
˚
2.0793(11), 2.0749(10) A for complex 3 and 2.083(2)
˚
and 2.094(2) A for complex 4, respectively, well in ac-
cord with the literature values [23]. The Ru–Cl bond
˚
˚
length is 2.4197(4) A for complex 3 and (2.4199(9) A)
for complex 4 slightly longer than the other reported
The complex [(g6-C6Me6)Ru(j2-O,O0-CH3COCH-
COC6H5)Cl] 3 crystallizes in the triclinic space group
P21/c (Fig. 2) where as the complex [(g6-C6Me6)Ru(j2-
˚
Ru–Cl bond distances (2.39 (A) [24]. The geometry of
the complexes is octahedral with a piano-stool structure,
and is marked by nearly 90ꢀ values for the bond angles
between the non-hexamethylbenzene ligands.
O,O0-C6H5COCHCOC6H5)Cl]
4 crystallizes in the
monoclinic space group P21/c (Fig. 3). The distance be-
Table 2
6
2
0
˚
Selected bond lengths (A) and bond angles (ꢀ) for [(g -C6Me6)Ru(j -O,O -CH3COCHCOC6H5)Cl] (3)
Bond lengths
Ru–C(1)
Ru–C(4)
Ru–O(1)
O(1)–C(13)
2.1881(15)
2.1624(15)
2.0793(11)
1.2693(19)
Ru–C(2)
Ru–C(5)
Ru–O(2)
O(2)–C(15)
2.1937(15)
2.1808(15)
2.0749(10)
1.2696(18)
Ru–C(3)
Ru–C(6)
Ru–Cl
Ru–C*
2.1888(15)
2.1846(15)
2.4197(4)
1.648(1)
Bond angles
O(2)–Ru–O(1)
O(1)–Ru–Cl
*
88.06(4)
87.07(3)
O(2)–Ru–Cl
84.63(3)
Ruthenium to centroid of HMB.

1224
P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
Table 3
6
2
0
˚
Selected bond lengths (A) and bond angles (ꢀ) for [(g -C6Me6)Ru(j -O,O -C6H5COCHCOC6H5)Cl] (4)
Bond lengths
Ru(1)–C(1)
Ru(1)–C(4)
Ru(1)–O(1)
O(1)–C(13)
2.172(4)
2.164(4)
2.083(2)
1.276(4)
Ru(1)–C(2)
Ru(1)–C(5)
Ru(1)–O(2)
O(2)–C(15)
2.172(3)
2.197(3)
2.094(2)
1.274(4)
Ru(1)–C(3)
Ru(1)–C(6)
Ru(1)–Cl(1)
Ru(1)–C*
2.202(4)
2.196(4)
2.4199(9)
1.653(1)
Bond angles
O(1)–Ru(1)–O(2)
O(1)–Ru(1)–Cl(1)
*
88.40(9)
87.20(7)
O(2)–Ru(1)–Cl(1)
84.60(7)
Ruthenium to centroid of HMB.
deposited with the Cambridge Crystallographic Data
Centre as supplementary Publication Nos. CCDC
246136 for complex 3 and CCDC 246137 for complex
4. Copies of the data can be obtained free of charge
on application to CCDC, 12 Union Road, Cambridge
CB2 1EZ, UK (fax: Int. code +(44) 1223/336033; e-mail:
deposit@ccdc.cam.ac.uk) or http://www.ccdc.cam.ac.
uk). Supplementary data associated with this article
can be found, in the online version at doi:10.1016/
j.jorganchem.2004.11.036.
References
[1] M.A. Bennett, M.I. Bruce, T.W. Matheson, in: G. Wilkinson,
F.G.A. Stone, E.W. Abel (Eds.), Comprehensive Organometallic
Chemistry, 4, Pergamon, Oxford, 1982, p. 796.
[2] H. Le Bozec, D. Touchard, P.H. Dixneuf, Adv. Organomet.
Chem. 29 (1989) 163.
[3] (a) M.A. Bennett, in: E.W. Abel, F.G.A. Stone, G. Wilkinson
(Eds.), Comprehensive Organometallic Chemistry II, 7, Perg-
amon, Oxford, 1995, p. 549.
[4] (a) J. Reedijk, J. Chem. Soc., Chem. Commun. (1996) 801;
(b) E. Wong, C.M. Giandomenico, Chem. Rev. 99 (1999) 2451
(references therein).
[5] I.W. McNae, K. Fishburne, A. Habtemariam, T.M. Hunter, M.
Melchart, F. Wong, M.D. Walkinshaw, P.J. Sadler, J. Chem.
Soc., Chem. Commun. (2004) 1786.
[6] H.L. Bozec, D. Touchard, P.H. Dixneuf, Adv. Organomet. Chem.
29 (1989) 165.
Fig. 3. ORTEP diagram of the complex 4 with 50% probability
thermal ellipsoids.
[7] R.I. Michelman, G.E. Ball, R.G. Bergman, R.A. Andersen,
Oragnometallics 13 (1994) 869.
[8] (a) D.A. Tocher, R.O. Gould, T.A. Stephenson, M.A. Bennett,
J.P. Ennett, T.W. Matheson, L. Sawyer, V.K. Shah, J. Chem.
Soc., Dalton Trans. (1983) 1571;
Acknowledgements
K.M.R. and P.G. thanks the Sophisticated Instru-
ments Facility (SIF), Indian Institute of Science, Banga-
lore, for providing the NMR facility. We are grateful to
Professor Pradeep Mathur of the National Single Crys-
tal X-ray Facility at the Indian Institute of Technology,
Bombay. We also thank Professor R.H. Duncan Lyn-
gdoh for his help in preparing the manuscript.
(b) M.L. Lehaire, R. Scopellitis, L. Heroties, K. Palbarn, P.
Mayer, K. Severin, Inorg. Chem. 43 (2004) 1609.
[9] W. Rigby, H.B. Lee, P.M. Bailey, J.A. McCleverty, P.M. Maitlis,
J. Chem. Soc., Dalton Trans. (1979) 387.
[10] D. Carmona, J. Ferrer, L.A. Oro, M.C. Apreda, C. Foces-Foces,
F.H. Cano, J. Elguero, M.L. Jimeno, J. Chem. Soc., Dalton
Trans. (1990) 1463.
[11] M.A. Bennett, T.R.B. Mitchell, M.R. Stevens, A.C. Willis, Can.
J. Chem. 79 (2001) 655.
[12] (a) M.A. Bennett, T.N. Huang, T.W. Matheson, A.K. Smith,
Inorg. Synth. 21 (1982) 74;
Appendix A. Supplementary data
(b) M.A. Bennett, T.W. Matheson, G.B. Robertson, A.K. Smith,
P.A. Tucker, Inorg. Chem. 19 (1980) 1014;
Crystallographic data (excluding structure factors)
for the structures reported in this paper have been
(c) Govindaswamy, H.P. Yennawar, M.R. Kollipara, J. Organo-
met. Chem. 689 (2004) 3108.

P. Govindaswamy et al. / Journal of Organometallic Chemistry 690 (2005) 1218–1225
1225
[13] XRD Single Crystal Software, Bruker Analytical X-ray Systems,
Madison, USA, 2002.
[19] M. Kilner, F.A. Hartman, A. Wojeicki, Inorg. Chem. (1967) 406.
[20] P. Govindaswamy, P.J. Carroll, Y.A. Mozharivskyj, M.R. Kol-
lipara, J. Organomet. Chem., in press.
[14] G.M. Sheldrick, SHELXS 86, Program for Crystal Structure
Solution, University of Go¨ttingen, Go¨ttingen, Germany, 1986.
[15] M. Sheldrick, SHELXS 97, Program for Crystal Structure
Refinement, University of Go¨ttingen, Go¨ttingen, Germany, 1997.
[16] C.K. Johnson, ORTEP-II: A Fortran Thermal Ellipsoid Plot
Program for Crystal Structure Illustrations, ORNL – 5138, 1976.
[17] K. Nakamoto, Infrared and Raman Spectra of Inorganic and
Coordination Compounds. Part B, fifth ed., Wiley interscience,
New York, 1997, pp. 91–100.
[21] A.G. Swallow, M.R. Truter, Proc. Roy. Soc. A254 (1960) 205.
[22] (a) R.Y.C. Shin, M.A. Bennett, L.Y. Goh, W. Chen, D.C.R.
Hockless, W.K. Leong, K. Mashima, A.C. Willis, Inorg. Chem.
42 (2003) 96;
(b) P. Govindaswamy, Y.A. Mozharivskyj, M.R. Kollipara, J.
Organomet. Chem. 689 (2004) 3265.
[23] M.A. Bennett, G. Chung, D.C.R. Hockless, H. Neumann, A.C.
Willis, J. Chem. Soc., Dalton Trans. (1999) 3451.
[18] M.L. Morris, R.W. Moshier, R.E. Sievers, Inorg. Chem. 2 (1963)
411.
[24] X.L. Lu, J.J. Vittal, E.R.T. Tiekink, G.K. Tan, S.L. Kuan, L.Y.
Goh, T.S.A. Hor, J. Organomet. Chem. 689 (2004) 1978.