Synthesis of ruthenium(ii) 1,2,3-trimethylindenyl complexes: X-ray crystal structure of [Ru(=C=C=CPh2)(η5-1,2,3-Me3C 9H4) (CO) (PPh3)][BF4]

Article abstract of DOI:10.1021/om970154w

The first ruthenium(II) 1,2,3-trimethylindenyl complexes have been prepared, including allenylidene, alkynyl, and alkenylcarbene derivatives. The X-ray crystal structure of [Ru(=C=C=CPh₂)(η⁵-1,2,3-Me₃C ₉H_4<

Full text of DOI:10.1021/om970154w

© Copyright 1997
Volume 16, Number 12, June 10, 1997
American Chemical Society
Communications
Syn th esis of Ru th en iu m (II) 1,2,3-Tr im eth ylin d en yl
Com p lexes: X-r a y Cr ysta l Str u ctu r e of
[Ru (dCdCdCP h 2)(η5-1,2,3-Me3C9H4)(CO)(P P h 3)][BF 4]
M. Pilar Gamasa, J ose´ Gimeno,* Covadonga Gonza´lez-Bernardo,
J avier Borge, and Santiago Garc´ıa-Granda
Departamento de Quı´mica Orga´nica e Inorga´nica and Departamento de Quı´mica Fı´sica y
Analı´tica, Instituto de Quı´mica Organometa´lica “Enrique Moles” (Unidad Asociada al CSIC),
Facultad de Qu´ımica, Universidad de Oviedo, 33071 Oviedo, Spain
Received February 27, 1997X
Summary: The first ruthenium(II) 1,2,3-trimethylinde-
nyl complexes have been prepared, including alle-
nylidene, alkynyl, and alkenylcarbene derivatives. The
X-ray crystal structure of [Ru(dCdCdCPh2)(η5-1,2,3-
Me3C9H4)(CO)(PPh3)] [BF4] is described.
complexes including alkynyl, alkenyl-carbene, and
allenylidene derivatives containing the fragments [Ru-
(η5-1,2,3-Me3C9H4)LL′] (L ) CO, L′ ) PR3; L-L′ ) bis-
(diphenylphosphino)methane (dppm)).
As expected, the half-sandwich moiety [Ru(η5-1,2,3-
Me3C9H4)LL′]+, containing a mixed CO-PR3 system or
the electron-releasing chelating ligand bis(diphenylphos-
phino)methane (dppm) as the ancillary ligands, is able
to stabilize carbene and allenylidene moieties. A mix-
ture of [Ru(η5-1,2,3-Me3C9H4)BrLL′]5 (L ) CO, L′ )
PPh3, PiPr3; L-L′ ) dppm) and AgBF4 in CH2Cl2 at room
temperature reacts with 1,1-diphenyl-2-propyn-1-ol to
give, after filtration of AgBr, the violet allenylidene
complexes [Ru(dCdCdCPh2)(η5-1,2,3-Me3C9H4)(CO)L]
[BF4] (1, 2; L ) PPh3, PiPr3) and [Ru(dCdCdCPh2)(η5-
1,2,3-Me3C9H4) (dppm)][BF4] (3) (65-85% yield) (Scheme
1). The spectroscopic properties of 1-3 are consistent6a
with the presence of the allenylidene moiety,2c in
particular, the ν(CdCdC) IR absorption (1924-1993
The chemistry of half-sandwich methyl-substituted
indenyl complexes of the late transition metals has been
scarcely studied compared to that of the analogous C5-
Me5 derivatives.1 In particular, as far as we are aware,
no methylindenyl ruthenium complexes have yet been
described, in spite of the potential interest of indenyl
complexes based on the enhanced reactivity (generally
associated with the indenyl effect) with respect to the
analogous cyclopentadienyl derivatives. During the last
few years, we have described2-4 the synthesis of novel
ruthenium(II) η5-indenyl complexes and have investi-
gated the influence of the indenyl ring in the chemical
behavior of unsaturated carbene derivatives. Herein,
we report the first ruthenium(II) 1,2,3-trimethylindenyl
(2) (a) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Lastra, E.; Borge,
J .; Garc´ıa-Granda, S. Organometallics 1994, 13, 745. (b) Gamasa, M.
P.; Gimeno, J ; Mart´ın-Vaca, B. M.; Borge, J .; Garc´ıa-Granda, S.; Pe´rez-
Carren˜o, E. Organometallics 1994, 13, 4045. (c) Cadierno, V.; Gamasa,
M. P.; Gimeno, J .; Gonza´lez-Cueva, M.; Lastra, E.; Borge, J .; Garc´ıa-
Granda, S.; Pe´rez-Carren˜o, E. Organometallics 1996, 15, 2137.
(3) Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C.; Mart´ın-Vaca,
B. M.; Monti, D.; Bassetti, M. Organometallics 1996, 15, 302.
(4) (a) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Lastra, E. J .
Organomet. Chem. 1994, 474, C27. (b) Cadierno, V.; Gamasa, M. P.;
Gimeno, J .; Borge, J .; Garc´ıa-Granda, S. J . Chem. Soc., Chem.
Commun. 1994, 2495.
X Abstract published in Advance ACS Abstracts, May 15, 1997.
(1) (a) Frankcom, T. M.; Green, J . C.; Nagy, A.; Kakkar, A. K.;
Marder, T. B. Organometallics 1993, 12, 3688. (b) Mlekuz, M.;
Bougeard, P.; Sayer, B. G.; McGlinchey, M. J .; Rodger, C. A.; Churchill,
M. R.; Ziller, J . W.; Kang, S.-K.; Albright, T. A. Organometallics 1986,
5, 1656. (c) Kakkar, A. R.; Taylor, N. J .; Marder, T. B.; Shen, J . K.;
Hallinan, N.; Basolo, F. Inorg. Chim. Acta 1992, 198-200, 219. (d)
Kakkar, A. K.; Stringer, G.; Taylor, N. J .; Marder, T. B. Can. J . Chem.
1995, 981. (e) Dunn, S. C.; Batsanov, A. S.; Mountford, P. J . Chem.
Soc., Chem. Commun. 1994, 2007. (f) Ready, T. E.; Chien, J . C. W.;
Rausch, M. D. J . Organomet. Chem. 1996, 519, 21.
S0276-7333(97)00154-4 CCC: $14.00 © 1997 American Chemical Society

2484 Organometallics, Vol. 16, No. 12, 1997
Communications
Sch em e 1. Syn th esis of Allen ylid en e a n d Alk yn yl
Com p lexes
cm-1) and the typical chemical shift, δ, in the 13C NMR
spectrum of the RudC carbon nucleus at 287.33-289.79
ppm (2J CP ) 15.3-16.4 Hz).2a,2c
F igu r e 1. ORTEP drawing of 1. Selected bond distances
(Å) and angles (deg): Ru-C1, 1.92(1); Ru-C99, 1.83(1);
Ru-P, 2.349(3); Ru-C*, 1.93(1); C99-O99, 1.15(1); C1-
C2, 1.26(1); C2-C3, 1.35(2); C3-C81, 1.47(2); C3-C91,
1.48(2); C99-Ru-C1, 92.1(5); C99-Ru-P, 86.8(4); C1-
Ru-P, 92.5(3); O99-C99-Ru, 176.(1); C2-C1-Ru, 172.-
(1); C1-C2-C3, 176.(1); C2-C3-C81, 120.(1); C2-C3-
C91, 120.(1). C* ) centroid of the indenyl ring.
Under similar reaction conditions, [Ru(η5-1,2,3-
Me3C9H4)Br(CO)(PPh3)] also reacts with phenylacety-
lene but a mixture containing the corresponding vi-
nylidene and the π-bonded alkyne complexes is obtained.
31P{1H} NMR spectrum of the mixture confirms the
presence of both species. All attempts to isolate the
vinylidene species have failed.7 The formation of the
transient vinylidene complex is assessed by the addition
of potassium tert-butoxide to this mixture, which leads,
after deprotonation, to the alkynyl complex [Ru(-C≡C-
CPh)(η5-1,2,3-Me3C9H4)(CO)(PPh3)] (4) (75% yield).6
It is well-known that the electrophilicity of the CR and
electronic nature of the metal fragment.8 We have
shown2c that the indenyl group in the complex [Ru-
{dCdCdCPh2}(η5-C9H7)(PPh3)2]+ exhibits a steric in-
fluence on the CR atom. As a consequence of the
preferred cis conformation of the indenyl ring with
respect to the unsaturated carbene chain, the benzo ring
of the indenyl group is over the CR atom.9 In order to
get information on the preferred conformation of the
analogous 1,2,3-Me3C9H4 group and on the overall
protection of the CR atom, a single-crystal X-ray struc-
tural determination of complex 1 was carried out.10
The structure shows (Figure 1) the typical pseudo-
octahedral three-legged piano-stool geometry, with a
nearly linear allenylidene group coordinated to the
ruthenium atom. Bond distances in the allenylidene
C
atoms of the allenylidene group depends on the
γ
(5) The halide complexes [Ru(η5-1,2,3-Me3C9H4)BrLL′] (L ) CO, L′
) PPh3, PiPr3; L-L′ ) bis(diphenylphosphino)methane (dppm)) are
easily prepared in high yields from [Ru(η5-1,2,3-Me3C9H4)X(CO)2] by
substitution of one or two carbonyl groups with the appropriate
phosphine. Gamasa, M. P.; Gimeno, J .; Gonza´lez-Bernardo, C. Un-
published results.
(6) (a) Synthesis of allenylidene complexes 1-3. General proce-
dure: A mixture of [Ru(η5-1,2,3-Me3C9H4)BrLL′] (0.80 mmol) and
AgBF4 (0.88 mmol) in CH2Cl2 (70 mL) was stirred under nitrogen for
15 min at room temperature in the absence of light. After the AgBr
formed was filtered, HC≡CC(OH)Ph2 (2.4 mmol) was added to the
solution, whose color changed immediately from yellow to violet. The
mixture was stirred for 15 min, the solvent evaporated, and the solid
residue washed several times with diethyl ether. A violet solid was
obtained (yield: 65-85%). Spectroscopic data for complex 1. 31P{1H}
NMR (δ, ppm): 48.20 (s). 1H NMR (δ, ppm): 1.85 (s, 3H, Me), 2.04 (s,
(8) (a) The following allenylidene complexes add alcohols at CR. (i)
[Ru(dCdCdCR2)(η6-arene)Cl(PR′3)]+: Pilette, D.; Ouzzine, K.; Le
Bozec, H.; Dixneuf, P. H.; Rickard, C. E. F.; Roper, W. R. Organome-
tallics 1992, 11, 809. (ii) [Ru(dCdCdCPh2)(η5-C5H5)(CO)(PiPr3)]+:
Esteruelas, M. A.; Go´mez, A. V.; Lahoz, F. J .; Lo´pez, A. M.; On˜ate, E.;
Oro, L. A. Organometallics 1996, 15, 3423. (b) The allenylidene group
is stable toward methanol or ethanol in the following complexes. (i)
[Ru(dCdCdCPh2)(η5-C5H5)(PMe3)2]+: Selegue, J . P. Organometallics
4
3H, Me), 2.21 (d, 3H, J HP ) 1.0 Hz, Me), 6.78-7.84 (m, 29H, H-4-7,
PPh3, Ph). 13C{1H} NMR (δ, ppm): 9.42 (Me), 10.47 (Me), 11.05 (Me),
2
92.74 (d, J CP ) 4.3 Hz), 94.37 (C-1 and C-3), 108.47, 112.97, 115.74
(C-2, C-3a, and C-7a), 121.02, 123.45 (C-4,7 or C-5,6), 129.08-142.2
3
(m, PPh3, Ph, C-4,7 or C-5,6), 166.94 (Cγ), 183.62 (d, J CP ) 1.8 Hz,
2
2
Câ), 201.09 (d, J CP ) 17.0 Hz, CO), 289.29 (d, J CP ) 15.9 Hz, CR). (b)
Spectroscopic data of complexes 4 and 5. 4: 31P{1H} NMR (δ, ppm)
1982, 1, 217. (ii) [Ru(dCdCdCR2)(η5-C9H7)(PPh3)2]+ (R ) Ph, R2
)
C12H8; C12H8 ) 2,2′-biphenyldiyl): ref 2c. (iii) [Ru(dCdCdCPh2)Cl(NP3)]+
(NP3 ) N(CH2CH2PPh2)3): Wolinska, A.; Touchard, P. H.; Dixneuf, P.
H.; Romero, A. J . Organomet. Chem. 1991, 420, 217. (iv) [Ru-
(dCdCdCRR′) Cl(dppm)2]+ (R ) R′ ) Ph; R ) H, R′ ) Ph, p-PhCl,
p-PhOMe): Pirio, N.; Touchard, D.; Toupet, L.; Dixneuf, P. H. Orga-
nometallics 1995, 14, 4920. (v) [Ru(dCdCdCRR′)Cl2{κP-iPr2PCH2CO2-
Me}{κ2P,O-iPr2PCH2CO2Me}] (R ) Ph, R′ ) Ph, o-Tol): Werner, H.;
Stark, A.; Steinert, P.; Gru¨nwald, C.; Wolf, J . Chem. Ber. 1995, 128,
49.
54.77 (s). 1H NMR (δ, ppm): 1.53 (s, 3H, Me), 1.94 (d, 3H, J HP ) 1.7
4
Hz, Me), 2.04 (s, 3H, Me), 6.63 (m, 1H), 6.71 (m, 1H), 6.82 (m, 1H),
6.96-7.40 (m, 21H, H-4-7, PPh3, Ph). 13C{1H} NMR (δ, ppm): 8.59
2
(Me), 9.95 (Me), 11.16 (Me), 85.56, 86.23 (d, J CP ) 5.0 Hz, C-1 and
2
C-3), 105.24, 109.01, 110.50 (d, J CP ) 8.1 Hz, C-2, C-3a, and C-7a),
2
109.87 (d, J CP ) 25.0 Hz, CR), 121.78-134.82 (m, C-4-7, Câ, PPh3,
2
Ph), 207.25 (d, J CP ) 18.6 Hz, CO). 5: 31P{1H} NMR (δ, ppm) 44.76
(bs). 1H NMR (δ, ppm): 1.46 (s, 3H, Me), 1.76 (s, 3H, Me), 1.85 (s, 3H,
Me), 4.00 (m, 3H, OMe), 5.09 (s, 1H, sCHd), 6.56-7.70 (m, 29H, H-4-
7, PPh3, Ph). 13C{1H} NMR (δ, ppm): 8.95 (Me), 10.19 (Me), 10.53 (Me),
67.63 (OMe), 88.30 (C-1 and C-3), 106.03, 116.99 (C-2, C-3a, and C-7a),
119.10 (Ind), 124.25 (Ind), 127.89 (Ind), 125.62-139.77 (m, Ind, sCHd,
PPh3, Ph), 145.48 (dCPh2), 204.15 (d, 2J CP ) 15.3 Hz, CO), 298.58 (m,
CR). Ind ) C-4,5,6, or 7.
(9) EHMO calculations are in accordance with these preferred
conformations in the solid state. Reference 2c.
(10) Crystal data: [C46H38OPRu][BF4]; Mr ) 825.61; monoclinic;
space group P21/n; a ) 14.834(6) Å, b ) 17.893(5) Å, c ) 14.93(1) Å; â
) 95.89(7)°; V ) 3941(4) Å3; Z ) 4; Fcalcd ) 1.391 g cm-3; F(000) )
1688; µ ) 0.49 mm-1; violet crystal (0.13 × 0.36 × 0.23 mm); 7466
reflections measured, 6917 used in refinement; full-matrix least-
squares refinement on F2; the BF4- anion exhibited severe structural
disorder; final R1 ) 0.062 and wR2 ) 0.154 (both for I > 2σ(I)); the
(7) (a) A similar equilibrium has also been observed at room
temperature for the analogous ruthenium fragment [Ru(η5-C5H5)-
(CO)(PPh3)]+: Nombel, P.; Lugan, N.; Mathieu, R. J . Organomet. Chem.
1995, 503, C22. (b) η2-Alkyne complexes have been isolated: Lomprey,
J . R.; Selegue, J . P. J . Am. Chem. Soc. 1992, 114, 5518. (c) Studies on
the ready isomerization of [Fe(η5-C5H5)(CO)2(dCdCRR′)]+ in the
corresponding η2-alkyne [Fe(η5-C5H5)(CO)2(η2-RC≡CR′)]+ have been
reported: Bly, R. S.; Zhong, Z.; Kane, C.; Bly, R. K. Organometallics
1994, 13, 899.
function minimized was [∑w(Fo - Fc2)2/∑w(Fo2)2]1/2, w ) 1/[σ2(Fo2) +
2
(0.1015*P)2 + (6.92*P)] where P ) (Max(Fo2,0) + 2*Fc2)/3 with σ2 (Fo
)
2
from counting statistics; number of parameters refined 470; residual
electronic density less than 0.91 e Å-3; maximum parameter shift to
esd ratio 0.051; T ) 293 K; Enraf-Nonius CAD4 diffractometer; λ (Mo
KR) ) 0.710 73 Å, ω-2θ scan technique (2° < θ < 25°).

Communications
Sch em e 2. Rea ctivity of Com p lex 1
Organometallics, Vol. 16, No. 12, 1997 2485
group, which is less sterically demanding and more
π-accepting than triphenylphosphine.
However, complex 1 reacts with anionic nucleophiles
in a different way, since only the addition to the Cγ atom
of the allenylidene chain takes place. Thus, the treat-
ment of 1 with NaOMe and NaC≡CH leads to the
alkynyl complexes 7 and 8 (Scheme 2). IR and NMR
(1H, 31P, 13C) data support the proposed formulations.
This behavior is in agreement with that of the related
complex [Ru(dCdCdCPh2)(η5-C9H7)(PPh3)2][PF6], which
also undergoes nucleophilic additions to give analogous
alkynyl complexes [Ru(η5-C9H7){C≡C-C(Nu)Ph2}(PPh3)2]
(Nu ) OMe, C≡CPh).4a
In summary, it is shown that nucleophilic additions
to the allenylidene chain in half-sandwich ruthenium-
(II) indenyl complexes depend on the steric and elec-
tronic properties of the ancillary ligands. It is also
apparent that the CO/PPh3 combination not only de-
termines the greater electrophilicity of the allenylidene
chain but also favors a less sterically demanding
orientation of the indenyl ring over the CR atom of the
allenylidene chain (Figure 1). Finally, it is worth noting
the different outcome of the nucleophilic additions
shown by complex 1 depending on the nature of the
incoming nucleophile. This raises the question of the
factors which are controlling the regioselectivity. Fur-
ther studies on the reactivity of trimethylindenyl ru-
thenium(II) allenylidene complexes and on the scope of
the nucleophilic additions along with theoretical calcu-
lations on the distribution of LUMO and HOMO on the
allenylidene chain are in progress.
chain (Ru-CR 1.92(1) Å, CR-Câ 1.26(1) Å, Câ-Cγ 1.35-
(1) Å) show the usual contribution of the resonant form
[Ru]-C≡CC+R2. The most interesting feature is the
conformation of the indenyl ligand, which shows an
orientation between the formally cis and trans orienta-
tion with respect to the allenylidene group,11 in contrast
to the cis orientation shown by the indenyl ligand in
[Ru{dCdCdCPh2}(η5-C9H7)(PPh3)2]+.2c Assuming that
no rotation of the indenyl ring around the ruthenium
atom takes place,12 this orientation should facilitate the
approach of the nucleophiles to the electrophilic sites
of the allenylidene chain. On the basis of these expec-
tations, we have examined the influence of the ancillary
ligands of the metal fragment [Ru(η5-1,2,3-Me3C9H4)-
LL′] on the reactivity of the allenylidene chain.
In accordance with the inertness of the related
complex [Ru(dCdCdCPh2)(η5-C9H7)(PPh3)2][PF6] to-
ward alcohols, complex 3 is also unreactive toward
refluxing methanol and other alcohols. In contrast,
complex 1 reacts with methanol and ethanol to give the
Ack n ow led gm en t. This work was supported by the
Direccio´n General de Investigacio´n Cient´ıfica y Te´cnica
(Project PB 90-384) and the E. U. (Human Capital and
Mobility Programme, Project ERBCHRXCT 940501).
We thank the Fundacio´n para la Investigacio´n Cient´ı-
fica y Te´cnica (FICYT) for a fellowship to C.G.-B.
R,â-unsaturated-alkoxycarbene complexes
5 and 6
(Scheme 2). Analytical and spectroscopic data are
consistent with this formulation.6b,13 The regioselective
nucleophilic addition to the CR atom of the allenylidene
chain in complex 1 to give the carbene species is
probably promoted by the presence of the carbonyl
Su p p or tin g In for m a tion Ava ila ble: Text giving syn-
thetic details and characterization data for 1-8 and text and
tables giving details of the X-ray diffraction study of 1 (22
pages). Ordering information is given on any current mast-
head page.
(11) The orientation may be established by the conformational angle
(CA), defined as the dihedral angle between the planes C** (centroid
of the benzo ring of the indenyl ligand), C*, and Ru and C*, Ru, and
C(1) of 79.6(5)° (0° and 180° for the cis and trans orientation,
respectively).
(12) A space-filling representation of complex 1 indicates that the
potential rotation of the indenyl ring around the ruthenium atom is
hindered by the phenyl rings of the triphenylphosphine and the
allenylidene chain: Borge, J .; Garc´ıa-Granda, S. Unpublished results.
OM970154W
(13) The structure of 6 has been confirmed by an X-ray diffraction
study (Borge, J .; Garc´ıa-Granda, S. Personal communication).