η5-Indenylruthenium(II) hydride complexes: Synthesis and protonation reactions

Article abstract of DOI:10.1016/S0020-1693(02)01457-3

Hydride complexes [RuH(η⁵-1,2,3-C₉R₃R′ ₄)LL′] (R=R′=H, LL′=dppm (1), dppe (2); L=L′=PMe₂Ph (3); L=PPh₃, L′=PMe₃ (4), PMe₂ Ph (5), PMePh₂ (6); L=CO, L′=P

Full text of DOI:10.1016/S0020-1693(02)01457-3

Inorganica Chimica Acta 347 (2003) 181ꢁ188
/
www.elsevier.com/locate/ica
h5-Indenylruthenium(II) hydride complexes:
synthesis and protonation reactions
M. Pilar Gamasa a, J. Gimeno a,*, Covadonga Gonza´lez-Bernardo a,
B.M. Mart´ın-Vaca a,1, Javier Borge b, Santiago Garc´ıa-Granda b
a Departamento de Qu´ımica Orga´nica e Inorga´nica, Facultad de Qu´ımica, Instituto de Qu´ımica Organometa´lica ‘Enrique Moles’ (Unidad Asociada al
CSIC), Universidad de Oviedo, 33071 Oviedo, Spain
b Departamento de Qu´ımica F´ısica y Anal´ıtica, Facultad de Qu´ımica, Universidad de Oviedo, 33071 Oviedo, Spain
Received 4 July 2002; accepted 25 September 2002
Dedicated to Professor Rafael Uso´n with great admiration for his outstanding contribution to modern Inorganic Chemistry
Abstract
5
?
Hydride complexes [RuH(h -1,2,3-C9R3R4)LL?] (Rꢀ
/
R?ꢀ
/
H, LL?ꢀ
/
dppm (1), dppe (2); Lꢀ
/
L?ꢀ
/
PMe2Ph (3); Lꢀ
/
PPh3, L?ꢀ
/
PMe3 (4), PMe2 Ph (5), PMePh2 (6); Lꢀ
/
CO, L?ꢀ
/
PiPr3 (7); Rꢀ
/
Me, R?ꢀ
/
H, LL?ꢀdppm (8); Lꢀ
/
/
CO, L?ꢀ
/
PPh3 (9), PiPr3 (10);
i
5
?
Rꢀ
/
R?ꢀ
/
Me, Lꢀ
/
CO, L?ꢀ
/
P Pr3 (11)) have been prepared by the reaction of complexes [RuX(h -1,2,3-C9R3R4)LL?] (Xꢀ
/
Cl, Br)
with an excess of NaOMe in methanol (reflux or room temperature). Protonation of the hydride complex [RuH(h5-C9H7)(PPh3)L]
(Lꢀ
/
PPh3 (12), PMe3 (4)) with HBF4×
/
OEt2 in Et2O yields the dihydride complexes [RuH2(h5-C9H7)(PPh3)L][BF4] (Lꢀ
/
PPh3 (13),
CH2Cl2 (13) have been
PMe3 (14)). Crystal structures of [RuH(h5-C9H7)(PPh3)2] (12) and [RuH2(h5-C9H7)(PPh3)2][BF4]×
determined by X-ray crystallography.
/
# 2002 Elsevier Science B.V. All rights reserved.
Keywords: Hydride complexes; Dihydride complexes; Indenyl; Ruthenium
1. Introduction
bond of unsaturated hydrocarbon molecules, since the
insertion of alkenes and alkynes constitutes one of the
key fundamental steps in many catalytic transforma-
tions [2]. The study of this type of process has become a
classic goal in the chemistry of hydride ruthenium
derivatives. We have recently reported regio and stereo-
Hydride transition metal complexes are among the
most important precursors in organometallic chemistry.
Group 8 derivatives, in particular ruthenium hydride
complexes, have been widely used both in stoicheio-
metric and catalytic processes [1].
Special relevance are the hydride complexes which are
prone to undergo insertion reactions into the RuꢁH
selective insertion reactions of alkynes into the RuꢁH
/
bond of indenylruthenium(II) hydride complexes [3,4]2
and we have found that such a reactivity is strongly
dependent on the ancillary ligands.
/
* Corresponding author. Tel.: ꢂ
446.
E-mail address: jgh@sauron.quimica.uniovi.es (J. Gimeno).
/
34-985-103-461; fax: ꢂ34-985-103-
/
1
2
Present address: Laboratoire d?He´te´rochimie Fondamentale et
Appliquee´ (UPRES-A CNRS 5069), 118 Route de Narbonne,
Universite´ Paul Sabatier (Baˆt 2R1), F-31062 Toulouse Cedex 04,
France.
The hydride complex [RuH(h5-C9H7)(dppm)] as well as the vinyl
derivative [Ru{(E)-CHÄ
(H)Ph}(h5-C9H7)(dppm)] are active species in
the catalytic dimerization of phenylacetylene to give (E) and (Z) 1,4-
/
diphenylbut-1-en-3-yne.
0020-1693/02/$ - see front matter # 2002 Elsevier Science B.V. All rights reserved.
PII: S 0 0 2 0 - 1 6 9 3 ( 0 2 ) 0 1 4 5 7 - 3

182
M.P. Gamasa et al. / Inorganica Chimica Acta 347 (2003) 181ꢁ188
/
When this work was initiated, only the indenyl
2.1. Synthesis and characterization of hydride complexes
[RuH(h5-C9H7)LL?] (LL?ꢀ
dppm (1), dppe (2); Lꢀ
L?ꢀPMe2Ph (3); LꢀPPh3, L?ꢀPMe3 (4), PMe2Ph
(5), PMePh2 (6); LꢀCO, L?ꢀ
PiPr3 (7)), [RuH(h5-
dppm (8); LꢀCO, L?ꢀ
hydride complex [RuH(h5-C9H7)(PPh3)2] was known
[5]. The limited availability of hydride ruthenium(II)
precursors required for the development of the above
mentioned insertion reaction studies led us to the
preparation of novel derivatives. Here, we report the
synthesis of indenyl-hydride complexes of the type
/
/
/
/
/
/
/
1,2,3-C9H4Me3)LL?] (LL?ꢀ
/
/
/
PPh3 (9), PiPr3 (10)) and [RuH(h5-
C9Me7)(CO)(PiPr3)] (11)
[RuH(h5-C9H7)LL?] (LL?ꢀ
L?ꢀPMe2Ph (3); LꢀPPh3, L?ꢀ
(5), PMePh2 (6); LꢀCO, L?ꢀ
PiPr3 (7)), [RuH(h5-
/
dppm (1), dppe (2); Lꢀ
/
Excess of NaOMe (ca. 5:1), prepared in situ by
reaction of NaOH and MeOH, was added to a suspen-
/
/
/PMe3 (4), PMe2Ph
/
/
5
?
sion of [RuX(h -1,2,3-C9R3R4)LL?] (Rꢀ
/
R?ꢀ
Br) (1 mmol) in MeOH
(100 ml). The mixture was stirred at room temperature
/
H, Xꢀ
/
1,2,3-C9H4Me3)LL?] (LL?ꢀ
/
dppm (8), Lꢀ
/
CO, L?ꢀ
/
PPh3 (9), PiPr3 (10)) and [RuH(h5-C9Me7)(CO)(PiPr3)]
(11).
Cl; Rꢀ
/
Me, R?ꢀ
/
H, Me, Xꢀ
/
(r.t.) (3ꢁ
/
6) or heated under reflux (1ꢁ
/
2, 7
/
11). When
On the other hand, it is now well established that
hydride ruthenium derivatives can be used as appro-
priate precursors of dihydride or dihydrogen complexes
through protonation reactions. For a number of cases
the equilibrium of dihydride/dihydrogen tautomers are
favored [6]. In this paper, we also describe the synthesis
and characterization of the dihydride complexes
ꢁ
the reaction was completed, the solvent was evaporated
and the residue was recrystallized from diethyl ether.
Reaction times, colour, yield (%), IR (KBr, n(RuÃ
/
H),
cmꢃ1), (MeOH, n(CO), cmꢃ1), analytical and 13C{1H}
NMR spectroscopic data are as follows: For 1, 3 h,
yellow solid; 80; 1994 w; Anal. Calc. for C34H30P2Ru: C,
67.88; H, 4.98. Found: C, 66.80; H, 4.80%. For 2, 3 h,
yellow solid; 70; 1981 w; Anal. Calc. for C35H32P2Ru: C,
66.70; H, 5.13. Found: C, 67.30; H, 5.10%. For 3, 1.5 h,
yellow oil; 75; 1962 w; Anal. Calc. for C25H30P2Ru: C,
60.84; H, 6.13. Found: C, 60.56; H, 6.05%. For 4, 2 h,
yellow solid; 85; 1974 w; Anal. Calc. for C30H32P2Ru: C,
64.80; H, 5.76. Found: C, 63.95; H, 5.90%. For 5, 2 h,
yellow solid; 80; 2043 w; Anal. Calc. for C35H34P2Ru: C,
68.06; H, 5.55. Found: C, 67.49; H, 5.65%. For 6, 2 h,
yellow solid; 85; 2008 w; Anal. Calc. for C40H36P2Ru: C,
70.61; H, 5.29. Found C, 69.80; H, 5.14%. For 7, 11 h;
orange solid; 70; 1994 w, 1916 vs; Anal. Calc. for
C19H29OPRu: C, 56.28; H, 7.21. Found: C, 55.51; H,
7.32%. For 8, 3.5 h; orange solid; 95; 1965 vw; 13C{1H}
[RuH2(h5-C9H7)(PPh3)L][BF4] (Lꢀ
/PPh3 (13), PMe3
(14)) obtained by reaction of HBF4×
/
OEt2 with the
hydride complexes [RuH(h5-C9H7)(PPh3)L].
2. Experimental
The reactions were carried out under dry nitrogen
using standard Schlenk techniques. Solvents were dried
by standard methods and distilled under nitrogen before
5
?
use. The complexes [RuX(h -1,2,3-C9R3R4)LL?] (Rꢀ
/
R?ꢀ
/
H, Xꢀ
/
Cl; Rꢀ
/
Me, R?ꢀ
/
H, Me, XꢀBr) and
/
[RuH(h5-C9H7)(PPh3)2] (12) were prepared by literature
(C6D6) d 12.87 (s, Me-1,3), 14.01 (s, Me-2), 57.23 (t,
2
21.5 Hz, PCH2P), 79.55 (d, JCP
methods [5,7].3
JCP
103.99 (s, C-3a,-7a), 104.15 (s, C-2), 121.39 and 122.98
ꢀ
/
ꢀ4.7 Hz, C-1,3),
/
Infrared spectra were recorded on a PerkinꢁElmer
/
Paragon 1000 spectrometer. The conductivities were
measured at room temperature, in ca. 10ꢃ3 mol dmꢃ3
acetone solutions, with a Jenway PCM3 conductimeter.
The C, H and N analyses were carried out with a
(s, C-4,7 or C-5,6), 123.97ꢁ
/
142.86 (m, Ph, C-4,7 or C-
2
5,6), 210.26 (d, JCP
ꢀ
/
17.1 Hz, CO). For 9, 8 h; yellow
solid; 85; 1967 w, 1920 vs; Anal. Calc. for C31H29OPRu:
C, 67.75; H, 5.32. Found: C, 67.78; H, 5.56; 13C{1H}
(C6D6) d 9.59 (s, Me), 11.69 (s, Me), 12.28 (s, Me), 81.90
PerkinꢁElmer 240-B microanalyzer. NMR spectra were
/
2
recorded on a Bruker AC300 instrument at 300 MHz
(1H), 121.5 MHz (31P) or 75.4 MHz (13C) or a Bruker
AC200 instrument at 200 MHz (1H), 81.01 MHz (31P) or
50.32 MHz (13C), using SiMe4 or 85% H3PO4 as
standards. 1H and 31P{1H} NMR spectroscopic data
(s) and 86.01 (d, JCP
ꢀ
/
8.3 Hz) (C-1 and C-3), 106.47
2.8 Hz) and 111.56 (s) (C-2, C-3a
and C-7a), 119.77 (s), 122.62 (s), 123.17 (s) and 124.94
(s) (C-4,5,6,7), 129.95ꢁ
138.48 (m, Ph), 209.25 (d, 2JCP
2
(s), 108.98 (d, JCP
ꢀ
/
/
ꢀ
/
15.7 Hz, CO). For 10, 2.5 h; yellow solid; 98; 2046 w,
1908 vs; Anal. Calc. for C22H35OPRu: C, 59.04; H, 7.88.
Found: C, 60.01; H, 8.14%; 13C{1H} (C6D6) d 11. 49 (s,
Me), 11.63 (s, Me), 13.85 (s, Me), 19.83, 20.45 (s,
for the hydride complexes (1ꢁ11) are collected in Table
/
1. The instability of complexes 8 and 11 prevented us
from obtaining any satisfactory analyses.
P(CH(CH3)2)3),
26.12
(d,
P(CH(CH3)2)3), 80.34 (s) and 84.53 (d, JCP
JCP
ꢀ
/
22.0
ꢀ
Hz,
7.3 Hz)
2
/
3
5
?
2
The halide complexes [RuBr(h -1,2,3-C9R3R4)LL?] (Rꢀ
R?ꢀH, LꢀCO, L?ꢀ dppm; RꢀR?ꢀMe, Lꢀ
PPh3, PiPr3; LL?ꢀ
CO, L?ꢀ
PiPr3) are easily prepared in high yields from [RuBr(h5-1,2,3-
/
Me,
(C-1 and C-3), 107.03 (s), 107.84 (d, JCP
112.09 (s) (Cꢁ2, C-3a and C-7a), 120.11 (s), 121.50 (s),
122.76 (s) and 123.44 (s) (C-4,5,6,7), 210.26 (d, JCP
17.1 Hz, CO). For 11, 1.5 h; orange oil; 98; 2061 w, 1899
ꢀ2.5 Hz) and
/
/
/
/
/
/
/
/
/
/
2
ꢀ
/
?
C9R3R4)(CO)2] by substitution of one or two carbonyl groups with the
appropriate phosphine.

Table 1
31P{1H} and 1H NMR data for the monohydride complexes a
Compound
31P{1H}
1H
h5-ringi
H-1,3
Ruꢁ/H
2JHP Others
H-2
Me-1,2,3,4,5,6,7
H-4,7, H-5,6
2
[RuH(h5-C9H7)(dppm)] (1)
19.14 s
5.34 d
(2.7)
5.23 t
(2.7)
6.65 (m, 2H) b
ꢃ
/
14.12 td c 31.2 3.62 (dt, 1H, JHH
PCH2P), 4.50 (ddt, 1H, JHH
2JHP
9.5, JHH 4.0, PCH2P), 7.10ꢁ
7.50 (m, 22H, H-4,7 or H-5,6, PPh2)
33.8 1.80 (m, 4H, P(CH2)2P), 7.24ꢁ7.67 (m,
ꢀ
/
14.2, JHP
ꢀ
14.2,
/
10.9,
ꢀ
/
ꢀ/
ꢀ/
/
[RuH(h5-C9H7)(dppe)] (2)
89.33 s
26.19 s
5.06 d
(2.0)
4.74 d
(2.4)
5.41 t
(2.0)
5.64 t
(2.4)
6.54 (m, 2H),
6.74 (m, 2H)
ꢃ
/
17.07 t
/
20H, PPh2)
[RuH(h5-C9H7)(PMe2Ph)2] (3)
ꢃ
/
16.90 t
34.2 1.30 (vt, 12H, jJHP JHP?jꢀ
ꢂ/
/8.4,
b
PMe2), 7.02ꢁ7.76 (m, 14H, H-4,5,6,7,
/
PPh)
16.12 dd 30.3, 0.90 (d, 9H, 2JHP
35.4 7.32 (m, 15H, PPh3)
[RuH(h5-C9H7)(PMe3)(PPh3)] (4)
8.00 d (PMe3) d,
69.80 d (PPh3) d
3.90 br s, 5.57 m
4.90 br s
6.15 (m, 1H),
6.80 (m, 1H),
6.96 (m, 1H)
7.46 (m, 1H)
6.04 (m, 1H) b
ꢃ
/
ꢀ/
18.4, PMe3), 7.01ꢁ
/
[RuH(h5-C9H7)(PMe2Ph)(PPh3)] (5)
[RuH(h5-C9H7)(PMePh2)(PPh3)] (6)
22.80 d (PMe2Ph) e,
68.99 d (PPh3) e
ꢃ
/
15.86 t
32.2 1.04 (m, 6H, PMe2), 6.77ꢁ
/
8.22 (m,
f
f
23H, H-4,5,6 or 7, PPh, PPh3)
h
h
2
15.44 dd 33.6, 1.17 (d, 3H, JHP
43.12 d (PMePh2) g,
68.59 d (PPh3) g
6.07 (m, 1H) b
ꢃ
/
ꢀ/7.6, PMe), 6.91ꢁ
/
29.9 7.92 (m, 28H, H-4,5,6 or 7, PPh2,
PPh3)
[RuH(h5-C9H7)(CO)(PiPr3)] (7)
86.24 s
19.98 s
6.84 (m, 2H),
7.00 (m, 1H),
7.30 (m, 1H)
ꢃ
/
14.88 d
12.85 t
30.5 0.84 (m, 18H, P(CH(Me)2)3), 1.58 (m,
3H, P(CH(Me)2)3)
i
i
[RuH(h5-1,2,3-C9H4Me3)(dppm)] (8)
2.42 (s, 3H, Me-2), 2.56
(s, 6H, Me-1,3)
ꢃ
/
30.2 3.66 and 4.45 (m, 1H each one,
b
PCH2P), 7.13ꢁ/7.89 (m, 24H, H-
4,5,6,7, PPh3)
b
[RuH(h5-1,2,3-C9H4Me3)(CO)(PPh3)] (9) 63.47s
RuH(h5-1,2,3-C9H4Me3)(CO)(PiPr3)] (10) 83.48 s
1.53 (s, 3H), 2.33 (s, 3H),
2.60 (s, 3H)
2.25 (s, 3H), 2.36 (s, 3H),
ꢃ
/
12.99 d
33.6 6.76ꢁ
/
8.08 (m, 19H, H-4,5,6,7, PPh3)
3
6.9, JHP
P(CH(Me)2)3), 1.14 (dd, 9H, JHH
7.14 (m, 2H),
7.26 (m, 1H),
7.62 (m, 1H)
ꢃ
/
14.23 d
32.1 1.04 (dd, 9H, JHH
ꢀ
/
ꢀ13.7,
/
4
2.59 (d, 3H, JHP
ꢀ/2.3)
ꢀ
/
3
6.9, JHP
(m, 3H, P(CH(Me)2)3)
33.0 0.76 (dd, 9H, JHH 6.9, JHP
P(CH(Me)2)3), 0.96 (dd, 9H, JHH
ꢀ13.7, P(CH(Me)2)3), 1.85
/
[RuH(h5-C9Me7)(CO)(PiPr3)] (11)
82.02 s
2.07 (s, 3H), 2.13 (s, 3H),
2.14 (d, 3H,4JHP
1.5), 2.26
(s, 3H), 2.36 (s, 3H), 2.54 (d,
3H, 4JHP
2.0), 2.64 (s, 3H)
ꢃ
/
14.18 d
ꢀ/
ꢀ12.8,
/
3
ꢀ/
ꢀ/
3
7.1, JHP
(m, 3H, P(CH(Me)2)3)
ꢀ/13.5, P(CH(Me)2)3), 1.72
ꢀ/
a
Spectra recorded in CD2Cl2 (1ꢁ
/
2), (CD3)2CO (3ꢁ
/
6) or C6D6 (7ꢁ11). d in ppm and J in Hz. Abbreviations: s, singlet; d, doublet; t, triplet; m, multiplet; vt, virtual triplet; br, broad. JHH in
/
parenthesis.
b
c
d
e
f
Overlapped by aromatic signals.
4JHH
4.0.
2JPP
31.7.
2JPP
30.0.
4.02, 4.46 and 5.59 (br s, 1H each one, H-1,2,3).
2JPP
28.7.
4.22, 4.56 and 5.90 (br s, 1H each one, H-1,2,3).
4.94, 5.38, 5.56 (br s, 1H each one, H-1,2,3). j Legend for atoms:
ꢀ
/
ꢀ
/
ꢀ/
g
h
i
ꢀ/

184
M.P. Gamasa et al. / Inorganica Chimica Acta 347 (2003) 181ꢁ188
/
vs; 13C{1H} (C6D6) d 14.75 (s, Me), 15.31 (s, Me), 15.81
(s, Me), 17.10 (s, Me), 17.37 (s, Me), 17.91 (s, Me), 18.00
(s, Me),), 19.50, 21.08 (s, P(CH(CH3)2)3), 28.82 (d,
Table 2
Crystallographic Data for Complexes 12 and 13×
/
CH2Cl2
CH2Cl2
C45H39BF4P2Ru×CH2Cl2
12
13×
/
JCP
2JCP
ꢀ
ꢀ
ꢀ
/
21.9 Hz, P(CH(CH3)2)3, 80.60 (s) and 85.43 (d,
7.0 Hz) (C-1 and C-3), 104.58 (s), 108.03(d,
3.1 Hz) and 113.06 (s) (C-2, C-3a and C-7a),
Formula
˚
C45H38P2Ru
10.968(8)
19.994(8)
16.676(6)
90
/
/
2JCP
124.97-132.04 (m, C-4,5,6,7), 210.98 (d, JCP
CO).
/
a (A)
˚
11.41(1)
12.07(2)
15.14(1)
89.0(1)
83.11(9)
67.6(1)
829.58
1913(4)
2
b (A)
˚
c (A)
2
ꢀ16.4 Hz,
/
a (8)
b (8)
g (8)
103.7(2)
90
2.2. Synthesis and characterization of the dihydride
complexes [RuH2(h5-C9H7)(PPh3)L][BF4] (Lꢀ
PPh3
(13), PMe3 (14))
Molecular weight
741.76
3553(3)
4
/
3
˚
V (A )
Z
Dcalc (g cmꢃ3
F(000)
)
˚
1.387
1528
1.441
848
A stirred solution of the hydride complexes [RuH(h5-
C9H7)(PPh3)L] (LꢀPPh3 (12), PMe3 (4)) (1 mmol) in
diethyl ether (100 ml), at r.t., was treated dropwise with
a dilute solution of HBF4×Et2O (1:1 molar ratio) in
diethyl ether. Immediately, an insoluble yellowꢁbrown
Wavelength (A)
T (K)
Radiation
0.71073
293
0.71073
200
/
Mo Ka
graphite cryst
P21/n
Mo Ka
graphite cryst
¯
P1
triclinic
/
Monochromator
Space group
Crystal system
Crystal size (mm3)
/
solid precipitated. After stirring for 15 min, the solution
was decanted and the solid washed with diethyl ether
monoclinic
0.30ꢄ/0.26ꢄ
/
0.26ꢄ
/
0.20ꢄ0.20
/
0.20
0.563
(3ꢄ20 ml) and vacuum-dried. Yield (%), IR (KBr,
/
m (mmꢃ1
)
0.545
v ꢁ2u
1.36ꢁ25.00
05h 513, ꢃ
175l 517
n(RuH), n(BF), cmꢃ1), conductivity (acetone, 20 8C,
Vꢃ1 cm2 molꢃ1), analytical and NMR spectroscopic
data are as follows: For 13, 80; 1974, 1059; 120; Anal.
Calc. for C45H39BF4P2Ru: C, 65.15; H, 4.74. Found: C,
Diffraction geom
v ꢁ
1.62ꢁ
h 5
k 5
195
Reflections measured 6802
/
2u
25.00
13,
23,
l 5
/
u Range (8)
/
/
Index ranges for data 05
/
/
/
/
/
125
/
k 514,
/
collected 05
/
/
ꢃ/
/
/
1
2
ꢃ/
/
/
19
65.84; H, 4.69%; H (CD2Cl2) d ꢃ
26.3 Hz, RuH2), 4.62 (t, 1H, JHH 2.4 Hz, H-2), 5.19 (d,
2H, JHH 2.4 Hz, H-1,3), 6.69 (m, 2H, H-4,7 or H-5,6),
7.20ꢁ
7.47 (m, 32H, H-4,7 or H-5,6, PPh3); 31P{1H}
/
8.29 (t, 2H, JHP
ꢀ
/
7101
ꢀ
/
Independent reflec-
tions
Variables
6232 [Rint
0.019]
438
ꢀ/
6727 [Rint
ꢀ/0.037]
ꢀ
/
/
479
Refinement method full-matrix least- full-matrix least-squares on
(CD2Cl2) d 59.38 (s). For 14: 75; 2005, 1057; 112; Anal.
Calc. for C30H33BF4P2Ru: C, 56.00; H, 5.17. Found: C,
squares on F2
1.025
F2
1.107
Goodness-of-fit
on F2
55.18; H, 4.86%; 1H (CD2Cl2) d ꢃ
/
9.72 (dd, 2H, 2JHP
ꢀ
/
2
2
28.0, JHP?ꢀ
9H, PMe3), 5.05 (t, 1H, JHH
JHH
and H-5,6), 7.28ꢁ
/
30.0 Hz, RuH2), 1.16 (d, JHP
ꢀ11.32 Hz,
/
Final R factors
R1 (4561 rflns)
R1 (5834 rflns)ꢀ
/0.0158,
ꢀ2.4 Hz, H-2), 5.54 (d, 2H,
/
(I ꢀ
/
2s(I))
ꢀ
/
0.0269, wR2
(4561 rflns)ꢀ
0.0693
R1ꢀ0.0542,
wR2 ꢀ0.0732
0.275 and ꢃ0.411 0.266 and ꢃ0.243
wR2 (5834 rflns)ꢀ
/0.0391
/
ꢀ2.4 Hz, H-1,3), 6.69, 7.10 (m, 2H each one, H-4,7
/
/
7.42 (m, 15H, PPh3); 31P{1H}
Final R factors
(all data) a
/
R1ꢀ
/
0.0191, wR2ꢀ0.0394
/
2
(CD2Cl2) d 46.53 (d, JPP?ꢀ
/20.0 Hz, PMe3), 62.47 (d,
/
2JPP?ꢀ
/20.0 Hz, PPh3).
Largest difference
peak and hole
/
/
ꢃ3
˚
(e A
)
2.3. X-ray diffraction
Data collection, crystal, and refinement parameters
are collected in Table 2. The unit cell parameters were
obtained from the least-squares fit of 25 reflections (with
u between 5 and 208 (12) and between 10 and 208 (13)).
Data were collected on a Nonius CAD4 diffractometer
0.060 for complex 12 and to Rꢀ0.098 for complex 13.
At this stage an empirical absorption corrections were
applied using DIFABS [13].
/
with the v ꢁ
/
2u scan technique and a variable scan rate,
Hydrogen atoms were geometrically placed, except
H(1) in complex 12. During the final stages of the
refinement, the positional parameters and the anisotro-
pic thermal parameters of the non-H atoms were
refined. The geometrically placed hydrogen atoms
were isotropically refined with a common thermal
parameter, riding on their parent atoms. H(1) in
complex 12 was also isotropically refined with an
independent thermal parameter. Hydride atoms could
not be found in complex 13.
with a maximum scan time of 60 s per reflection. The
final drift correction factors were between 0.99 and 1.01
(12) and between 0.71 and 1.05 (13). On all reflections,
profile analysis [8,9] were performed. Lorentz and
polarization corrections were applied and the data
were reduced to jFoj values.
The structures were solved by DIRDIF [10] (Patterson
methods and phase expansion). Isotropic least-squares
refinement using SHELX-76 [11,12] converged to Rꢀ
/

M.P. Gamasa et al. / Inorganica Chimica Acta 347 (2003) 181ꢁ
/188
185
PPh3
PMe3
PPh3
PMe2Ph
PPh3
PMePh2
CO
PPh3
CO
PiPr3
h5-ring/L,L?
dppm
dppe
2PMe2Ph
h5-C9H7
1
8
2
3
4
5
6
7
10
11
h5-1,2,3-C9H4Me3
h5-C9Me7
9
Finally, full-matrix least-squares refinements on Fo2
were made, for complexes 12 and 13, using SHELXL-93
[14].
Me, XꢀBr) with an excess of NaOMe (ca. 1:20) in
/
refluxing methanol (or at room temperature for 3ꢁ6)
/
affords the hydride complexes [RuH(h5-1,2,3-
?
C9R3R4)LL?] (1ꢁ
/11) (Eq. (1)).
a) Complex 12: the function minimized was [S w(Fo2ꢃ
Fc2)2/S w(Fo2)2]1/2 1/[s2(Fo2)ꢂ(0.0410P)2]
wꢀ
where Pꢀ
(max(Fo2, 0)ꢂ2Fc2)/3 with s2(Fo2) from
/
The progress of the reaction has been monitored, in
the case of the carbonyl derivatives, by infrared spectro-
scopy in the carbonyl region. The reactions are discon-
tinued when the IR spectra only show a new n(CO)
,
/
/
/
/
counting statistics. The maximum shift to e.s.d.
ratio in the last full-matrix least-squares cycle was
absorption between 1920ꢁ
/
1899 cmꢃ1
.
ꢃ0.082. The final difference Fourier map showed
/
All the complexes are isolated (70ꢁ/98% yield) as
no peaks higher than 0.27 e Aꢃ3, nor deeper than ꢃ
/
˚
yellow or orange solids (except 3 and 11 which are oils),
and are very air and moisture-sensitive in solution and
in solid state. These complexes are soluble in polar and
non-polar solvents as diethyl ether and hexane, but
some of them react with chorinated solvents to give the
corresponding chloro-ruthenium complexes. They have
been characterized by elemental analyses, IR and NMR
(1H, 31P{1H} and 13C{1H}) spectroscopy (details are
given in Section 2 and in Table 1).
ꢃ3
˚
0.41 e A
b) Complex 13×
[S w(Fo2ꢃFc2)2/S w(Fo2)2]1/2
.
/
CH2Cl2: the function minimized was
wꢀ
1/[s2(Fo2)ꢂ
2Fc2)/3 with
/
,
/
/
(0.0197P)2] where Pꢀ
/
(max(Fo2, 0)ꢂ
/
s2(Fo2) from counting statistics. The maximum shift
to e.s.d. ratio in the last full-matrix least-squares
cycle was ꢃ0.005. The CH2Cl2 solvent molecule
/
was affected by strong structural disorder and could
not be located. Therefore, it was omitted from the
parameter set of the refined discrete-atom model. It
was taken into account in the structure factor
calculations by direct Fourier transformation of
the electron density in the corresponding cavity,
using BYPASS [15]. The final difference Fourier
Significant spectroscopic features are: (i) A weak
H) absorption at ca. 2043ꢁ
1967 cmꢃ1
intensity n(Ruꢁ
/
/
in the IR spectra (KBr) (see Section 2). (ii) The
resonance of the hydride group appears in the 1H
NMR spectra at very high field (d ꢃ
/
12.85 to ꢃ17.07)
/
map showed no peaks higher than 0.27 e Aꢃ3, nor
˚
in accordance with the data reported in the literature
[19,20] for other analogous cyclopentadienyl hydride
ruthenium complexes. The signal is observed as a
ꢃ3
˚
0.24 e A
deeper than ꢃ
/
.
Atomic scattering factors were taken from Interna-
tional Tables for X-ray Crystallography (1974) [16].
Geometrical calculations were made with PARST [17].
The crystallographic plots were made with EUCLID [18].
All calculations were made at the University of Oviedo
on the X-ray group ALPHA-AXP computers.
doublet (7, 9ꢁ11), triplet (2, 3, 5, 8), doublet of doublets
/
2
(4, 6) or triplet of doublets (1), the JHP coupling being
ca. 30 Hz (see Table 1). It is worth noting that the
hydride signal for complex 1 appears as a triplet of
4
doublets (2JHP
ꢀ
/
31.2, JHH
ꢀ4.0 Hz) by coupling with
/
two phosphorus atoms and one methylene proton of the
dppm ligand [21]4. (iii) A single resonance in the
31P{1H} NMR spectra consistent with the chemical
3. Results and discussion
equivalence of the phosphorus atoms (1ꢁ/3, 8) or with
the presence of a unique phosphorus atom (7, 9ꢁ
/11).
3.1. Synthesis of hydride ruthenium(II) complexes
The treatment of complexes [RuX(h5-1,2,3-
4
This type of coupling has been already reported in the complex
[RuH(h5-C5Me5)(dppm)].
?
C9R3R4)LL?] (Rꢀ
/
R?ꢀ
/
H, Xꢀ
/
Cl; Rꢀ
/
Me, R?ꢀ/H,

186
M.P. Gamasa et al. / Inorganica Chimica Acta 347 (2003) 181ꢁ188
/
The spectra of complexes 4ꢁ/6, which have two different
corresponding dihydrogen tautomers is dependent on
the metals and auxiliary ligands. So, the use of mono-
dentate phosphines favors the formation of the dihy-
dride complexes while the stability of h2-dihydrogen
complexes is favored by bidentate diphosphines of small
chelating ring sizes. We have tried the protonation of the
phosphines, show two doblets.
The formation of these complexes can be easily
explained on the basis of the classical route for the
synthesis of transition metal hydride derivatives (see
Scheme 1), which involves the b-hydrogen elimination
from a methoxide intermediate complex to give the
hydride complex and formaldehyde [19].
complexes 1 and 2 with HBF4×
/
Et2O in Et2O or Me2CO-
d6 at 203 K yielding the dihydrogen complex [Ru(h2-
H2)(h5-C9H7)(dppm)][BF4] and a mixture of dihydrogen
[Ru(h2-H2)(h5-C9H7)(dppe)][BF4]
and
dihydride
[RuH2(h5-C9H7)(dppe)][BF4] complexes, respectively.
When these Me2CO-d6 solutions are allowed to warm
to room temperature, the complexes [RuH(h6-
C9H8)(dppm)][BF4] and [RuH(h6-C9H8)(dppe)][BF4]
are generated. These variable temperature NMR studies
are in accordance with those recently described by Jia
[6j] and do not merit further comments.
Scheme 1.
3.2. Synthesis of dihydride complexes [RuH2(h5-
C9H7)L2][BF4] (Lꢀ
/
PPh3 (13), PMe3 (14))
The treatment of a solution of complexes [RuH(h5-
3.3. Molecular structure of complexes [RuH(h5-
C9H7)(PPh3)2] (12) and [RuH2(h5-
C9H7)L2][BF4] (LꢀPPh3 (12), PMe3 (4) in diethyl ether
with a solution of HBF4×OEt2 (1:1 molar ratio), at room
temperature, affords the dihydride complexes 13 and 14
as insoluble yellowꢁbrown solids (75ꢁ80% yield). These
/
/
C9H7)(PPh3)2][BF4]×
/
CH2Cl2 (13×
/
CH2Cl2)
/
/
The structures of the complex 13 as well as of the
hydride precursor 12 have been determined by single-
crystal X-ray analysis. ORTEP type views of the mole-
cular structures of 12 and of the cation of 13 are shown
in Figs. 1 and 2 and selected bond distances and angles
are collected in Table 3. The complex 12 shows the
typical pseudoctahedral three-legged piano stool geo-
metry of indenyl ruthenium(II) complexes [22] in which
the metal atom is bonded to the h5 indenyl group, to
two phosphorus atoms and to the hydrogen atom. The
geometry of the cation of 13 is best described in terms of
‘four-legged piano stool’ with the ‘legs’ comprising the
phosphines and the hydride ligands. Although the
hydride ligands could not be reliably located for 13,
their positions can be inferred from the observed
molecular geometry. Thus, the angle between the C5H5
plane of indenyl ligand and the ML2 plane is 87.93(14)8
complexes are soluble in acetone and chlorinated
solvents and insoluble in non-polar solvents as diethyl
ether and hexane. They have been characterized by
elemental analyses, IR and NMR (1H and 31P{1H})
spectroscopy (details are given in Section 2). Significant
spectroscopic features are: (i) A weak intensity n(RuꢁH)
/
absorption at ca. 1974 (13) and 2005 cmꢃ1 (14) in the IR
spectra (KBr). (ii) The resonance of the hydride group
1
appears in the H NMR spectra at very high field as a
triplet (d ꢃ
doublets for 14 (d ꢃ
/
8.29, 2JHP
ꢀ
/
26.3 Hz) for 13 and a doublet of
/
9.72, 2JHP 30.0, 2JHP?ꢀ
ꢀ
/
/28.0 Hz).
(iii) The 31P{1H} NMR spectra show a single resonance
(13) and two doublets (14), in accordance with the
chemical equivalence and inequivalence of the phospho-
rus atoms.
When the protonation of the complex 12 is carried out
in Et2O, at 203 K, the dihydride complex (13) is also
and the Pꢁ
/
Ruꢁ
/
P angle is 114.3(1)8, in the ranges
reported for Lemke and Brammer for other [MH2Cp?L2]
exclusively formed as insoluble yellowꢁ
should be noted that complex
/
brown solid. It
[RuH2(h5-
C9H7)(PPh3)2][BF4] (13) is also the only species observed
(M (d4), Cp?ꢀh5-C5H5, h5-C5Me5, h5-C5H4Me) com-
/
plexes [20a]5. These values confirm the trans dihydride
structure of complex 13, with a four-legged piano stool
geometry, even without locating the hydride ligands
crystallographically. To our knowledge there is no
experimental evidence to support the presence of a cis-
1
in the H NMR spectrum (CD2Cl2, room temperature),
as well as after crystalization (CH2Cl2/Et2O, room
temperature). Jia and coworkers have recently reported
the formation of the similar complex [RuH2(h5-
C9H7)(PPh3)2][CF3SO3] which is generated and spectro-
scopically characterized in situ at low temperature.
However, it is reported that the complex is unstable at
room temperature in THF-d8 giving the complex
[RuH(h6-C9H8)(PPh3)2][CF3SO3] via proton migration
[6j].
5
For leading references see Lemke and Brammer who have
reported several general structural trends between related [MHCp?L2]
(M (d6)) and [MH2Cp?L2] (M (d4)) (Cp?ꢀh5-C5H5, h5-C5Me5, h5-
/
C5H4Me) complexes: the mean angle between the Cp?plane and the
ML2 is 67.6(13) and 87.6(4)8, respectively and the mean angle LꢁMꢁ
L? is 93.0(19) and 107.2(10)8, respectively. On the other hand, the angle
between the MꢁH vector and the normal to the ML2 plane is generally
less than 108 (mean 7.9(12)8) for d6 [MHCp?L2] complexes.
/
/
It is known, from previous literature data [6c], that
the stability of dihydride complexes relative to the
/

M.P. Gamasa et al. / Inorganica Chimica Acta 347 (2003) 181ꢁ
/188
187
Table 3
Selected bond distances, slip parameter D (A), bond, dihedral, FA ,
a
b
˚
HA c and CA d angles (8) for complexes 12 and 13×
/CH2Cl2
12
13
Bond distances
Ruꢁ
Ruꢁ
Ruꢁ
Ruꢁ
/
P1
P2
H1
C*
2.271(1)
2.279(3)
1.57(3)
2.321(4)
2.276(4)
/
/
/
1.945(3)
0.154(3)
1.928(2)
0.102(3)
D
Bond angles
C*ꢁ
C*ꢁ
C*ꢁ
P1ꢁRuꢁ
P1ꢁRuꢁ
P2ꢁRuꢁ
/
Ruꢁ
Ruꢁ
Ruꢁ
/
P1
P2
H1
127.4(1)
129.0(1)
118.69(95)
99.13(7)
83.9(9)
126.4(4)
119.2(3)
/
/
/
/
/
/
P2
114.3(1)
/
/
H1
H1
/
/
81.6(9)
FA
HA
CA
8.4(3)
5.1(3)
15.06(71)
8.6(2)
4.8(2)
Fig. 1. ORTEP type view of the molecular structure of the hydride
complex [RuH(h5-C9H7)(PPh3)2] (12) drawn at 30% probability level.
For clarity, only the C ipso of the aryl groups of the triphenylpho-
sphine ligands are drawn.
a
Dꢀ
/
d(Ruꢁ
/
C74, C70)ꢁ
/
d(Ruꢁ/C71, C73).
b
FA (fold angle)ꢀ
/
angle between the planes defined by [C71, C72,
C73] and [C70, C74, C75, C76, C77, C78].
c
HA (hinge angle)ꢀ
/
angle between the planes defined by [C71,
C72, C73] and [C73, C74, C70, C71].
dihydride species in any of the [RuH2Cp?L2]ꢂ systems
studied to date [6c,20b,f].
d
CA (conformational angle)ꢀ
[C**, C*, Ru] and [C*, Ru, H1]. C*ꢀ
C74. C**ꢀcentroid of C70, C74, C75, C76, C77, C78.
/
angle between the planes defined by
/
centroid of C70, C71, C72, C73,
/
The rutheniumꢁ
/
hydride ligand was located and
H1 bond distance of
1.57(3) A, in the range found for analogous semisand-
refined in 12 to give a Ruꢁ
/
˚
99.13(7)8 and the angle between the MꢁH vector and
/
wich hydride cyclopentadienyl complexes (range 1.427ꢁ
/
the normal to the ML2 plane is 11.32(85)8 [20a]. The
orientation of the hydride ligand in complex 12 is almost
˚
1.630 A) [20] and comparable to that of the analogue
5
˚
[RuH(h -C9H7)(dppm)] (1.59(2) A) [6j]. The angle
between the C5H5 plane of indenyl ligand and the
trans (CAꢀ15.06(71)8) relative to the benzo ring of the
/
indenyl ligand, in accordance with the relative trans
ML2 plane is 78.32(10)8, the Pꢁ
/
Ruꢁ
/
P
angle is
influence of the hydride and phosphine ligands [22,23].
Fig. 2. ORTEP type view of the molecular structure of the dihydride cation complex [RuH2(h5-C9H7)(PPh3)2]ꢂ (13) drawn at 30% probability level.
For clarity, only the C ipso of the aryl groups of the triphenylphosphine ligands are drawn.

188
M.P. Gamasa et al. / Inorganica Chimica Acta 347 (2003) 181ꢁ188
/
[5] L.A. Oro, M.A. Ciriano, M. Campo, C. Foces-Foces, F.H. Cano,
J. Organomet. Chem. 289 (1985) 117.
The rest of the main structural parameters are rather
similar to those found for analogous indenylꢁphosphi-
/
[6] (a) G.J. Kubas, Metal Dihydrogen and s-Bond Complexes:
Structure, Theory and Reactivity, Kluwer, New York, 2001;
(b) J.K. Law, H. Mellows, D.M. Heinekey, J. Am. Chem. Soc.
122 (2002) 1024;
noruthenium(II) complexes reported by us [22] and,
therefore, do not deserve further analysis.
(c) G. Jia, C-P. Lau, Coord. Chem. Rev. 190ꢁ
references therein);
(d) S. Sabo-Ettiene, B. Chaudret, Coord. Chem. Rev. 178ꢁ
(1998) 381;
/
192 (1999) 83 (and
4. Supplementary material
/
180
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 188860 and 188861 for
(e) D.M. Heinekey, W.J. Oldham, Jr, Chem. Rev. 93 (1993) 913;
(f) P.G. Jessop, R.H. Morris, Coord. Chem. Rev. 121 (1992) 155;
(g) R.H. Crabtree, Angew. Chem., Int. Engl. Ed. 32 (1993) 789;
(h) R.H. Crabtree, Acc. Chem. Rev. 23 (1990) 95;
(i) For an account of the catalytic activity of dihydrogen
complexes see: M.A Esteruelas, L.A. Oro, Chem. Rev. 98 (1988)
577;
compounds 12 and 13×/CH2Cl2, respectively. Copies of
this information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge, CB2
1EZ, UK (fax: ꢂ44-1223-336-033; e-mail: deposit@
/
(j) M.Y. Hung, S.M. Ng, Z. Zhou, C.P. Lau, G. Jia, Organome-
tallics 19 (2000) 3692.
ccdc.cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
[7] (a) M.P. Gamasa, J. Gimeno, C. Gonza´lez-Bernardo, B. Mart´ın-
Vaca, D. Monti, M. Bassetti, Organometallics 15 (1996) 302;
(b) M.P. Gamasa, J. Gimeno, C. Gonza´lez-Bernardo, Unpub-
lished results.
Acknowledgements
[8] D.F. Grant, E.J. Gabe, J. Appl. Crystallogr. 11 (1978) 114.
[9] M.S. Lehman, F.K. Larsen, Acta Crystallogr., A 30 (1974) 580.
[10] P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, S.
Garc´ıa-Granda, R.O. Gould, J.M.M. Smits, C. Smykalla, The
DIRDIF Program System, Technical Report, Crystallographic
Laboratory, University of Nijmegen, Nijmegen, 1992.
[11] G.M. Sheldrick, SHELX-76, Program for Crystal Structure Deter-
mination, University of Cambridge, Cambridge, 1976.
[12] J.F. van der Maelen Ur´ıa, PhD thesis, University of Oviedo,
Spain, 1991.
This work was supported by the Ministerio de Ciencia
y Tecnolog´ıa (MCT, Project BQU 2000-0227). We
thank the Fundacio´n para la Investigacio´n Cient´ıfica y
Te´cnica de Asturias (FICYT) for the fellowships
granted to B.M. M.-V. and C.G.-B.
References
[13] N. Walker, D. Stuart, Acta Crystallogr., Sect. A 39 (1983) 158.
[14] G.M. Sheldrick, SHELXL-93, in: H.D. Flack, P. Parkanyi, K.
Simon (Eds.), Crystallographic Computing 6, IUCr/Oxford Uni-
versity Press, Oxford, 1993.
[1] (a) A. Dedieu (Ed.), Transition Metal Hydrides, VCH, New York,
1992;
(b) J.A. Martinho Simoes, J.L. Beauchamp, Chem. Rev. 90 (1990)
629;
[15] P. Van der Sluis, A.L. Spek, Acta Crystallogr., A 46 (1990) 194.
[16] International Tables for X-ray Crystallography, vol. IV, Kynoch
Press, Birmingham, 1974.
(c) S. Otsuka, A. Nakamura, Adv. Organomet. Chem. 14 (1976)
245;
[17] M. Nardelli, Comput. Chem. 7 (1983) 95.
(d) P.A. Chaloner, M.A. Esteruelas, F. Joo´, L.A. Oro, Homo-
geneous Hydrogenation, Kluwer, Dordrecht, 1994;
(e) M. Peruzzini, R. Poli, Recent Advances in Hydride Chemistry,
Elsevier, Amsterdam, 2001.
[18] A.L. Spek, The EUCLID Package, D. Sayre (Ed.), Computational
Crystallography, Clarendon Press, Oxford, 1982, p. 528.
[19] M.I. Bruce, M.G. Humphrey, A.G. Swincer, R.C. Wallis, Aust. J.
Chem. 37 (1984) 1747.
[2] (a) G.W. Parshall, S.D. Ittel, Homogeneous Catalysis, 2nd ed.,
Wiley, New York, 1992;
[20] (a) F.R. Lemke, L. Brammer, Organometallics 14 (1995) 3980;
(b) L. Brammer, W.T. Klooster, F.R. Lemke, Organometallics 15
(1996) 1721 (and references therein);
(b) R.H. Crabtree, The Organometallic Chemistry of the Transi-
tion Metals, 2nd ed., Wiley, New York, 1994;
(c) G.O. Spessard, G.L. Miessler, Organometallic Chemistry,
Prentice Hall, Upper Saddle River, NJ, 1997;
(d) J.P. Collman, L.S. Hegedus, J.R. Norton, R.G. Finke,
Principles and Applications of Organotransition Metal Chemis-
try, University Science Books, Mill Valley, CA, 1987.
[3] (a) M. Bassetti, P. Casellato, M.P. Gamasa, J. Gimeno, C.
Gonzalez-Bernardo, B. Mart´ın-Vaca, Organometallics 16 (1997)
5470;
(c) R.T. Hembre, J.S. McQueen, V.W. Day, J. Am. Chem. Soc.
118 (1996) 798;
(d) A.C. Ontko, J.F. Houlis, R.C. Schnabel, D.M. Roddick, T.P.
Fong, A.J. Lough, R.H. Morris, Organometallics 17 (1998) 5467
(and references therein);
(e) C. Romming, K.T. Smith, M. Tilset, Inorg. Chim. Acta 259
(1997) 281;
(f) G. Jia, C-P. Lau, J. Organomet. Chem. 565 (1998) 37.
[21] G. Jia, R.H. Morris, J. Am. Chem. Soc. 113 (1991) 875.
[22] V. Cadierno, J. D´ıez, M.P. Gamasa, J. Gimeno, E. Lastra, Coord.
(b) K. Bieger, J. D´ıez, M.P. Gamasa, J. Gimeno, M. Pavlisˇta, Y.
´
Rodr´ıguez-Alvarez, S. Garc´ıa-Granda, R. Santiago-Garc´ıa, Eur.
Chem. Rev. 193ꢁ195 (1999) 147.
[23] J.W. Faller, R.H. Crabtree, A. Habib, Organometallics 4 (1985)
/
J. Inorg. Chem. (2002) 1647.
[4] M. Bassetti, S. Marini, F. Tortorella, V. Cadierno, J. D´ıez, M.P.
Gamasa, J. Gimeno, J. Organomet. Chem. 593ꢁ594 (2000) 292.
/
929.