[(2-4-η)-butadienyl]- and [(3-5-η)-pentatrienyl]ruthenium complexes from vinylidene and allenylidene precursors

Article abstract of DOI:10.1021/om960390r

The vinylideneruthenium complex [C₅H₅-RuCl(=C=CHCO₂Me)(PPh₃)] (2), which is obtained on stepwise treatment of [C₅H₅Ru(η³-C₃H ₄Me)(PPh₃)] (1) with HC≡CCO₂Me and HCl in aromatic solvents, reacts with Sn(CH=CH₂)₄ in the presence of CuCl to give the (2-4-η)-butadienyl compound [C₅H₅Ru(η³-CH₂CHC=C-HCO ₂Me)] (3) in abut 70% yield. A similar C-C coupling reaction leading to the formation of the (3-5-η)-pentatrienyl metal complex. [C₅H₅Ru{(3-5-η)-CH₂-CHC=C=CPh ₂}(PPh₃)] (5) occurs on treatment of the allenylidene compound [C₅Me₅RuCl(=C=C=CPh₂){κ(P)-iPr ₂PCH₂CO₂Me}] (4) with CH₂=CHMgBr in C₆H₆/ THF.

Full text of DOI:10.1021/om960390r

Organometallics 1996, 15, 4075-4077
4075
Notes
[(2-4-η)-Bu ta d ien yl]- a n d
[(3-5-η)-P en ta tr ien yl]r u th en iu m Com p lexes fr om
Vin ylid en e a n d Allen ylid en e P r ecu r sor s1
Thomas Braun, Petra Meuer, and Helmut Werner*
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg,
Am Hubland, D-97074 Wu¨rzburg, Germany
Received May 21, 1996X
Sch em e 1
Summary: The vinylideneruthenium complex [C5H5-
RuCl(dCdCHCO2Me)(PPh3)] (2), which is obtained on
stepwise treatment of [C5H5Ru(η3-C3H4Me)(PPh3)] (1)
with HCtCCO2Me and HCl in aromatic solvents, reacts
with Sn(CHdCH2)4 in the presence of CuCl to give the
(2-4-η)-butadienyl compound [C5H5Ru(η3-CH2CHCdC-
HCO2Me)] (3) in abut 70% yield. A similar CsC
coupling reaction leading to the formation of the (3-5-
η)-pentatrienyl metal complex [C5H5Ru{(3-5-η)-CH2-
CHC)CdCPh2}(PPh3)] (5) occurs on treatment of the
allenylidene compound [C5Me5RuCl(dCdCdCPh2){κ(P)-
iPr2PCH2CO2Me}] (4) with CH2dCHMgBr in C6H6/
THF.
We have recently shown that migratory insertion of
vinylidene ligands into metal-alkyl, metal-aryl, and
metal-vinyl bonds provides a novel route to (η3-allyl)-
and (η3-butadienyl)rhodium complexes.2 Since we ar-
gued that the CsC coupling reaction leading to the allyl
and butadienyl units might be facilitated by the coor-
dinative unsaturation at the rhodium(I) center, we were
interested to find out whether a similar process could
also occur in the coordination sphere of a (cyclopenta-
dienyl)ruthenium(II) compound where the metal has an
18-electron configuration. We note that recently both
Wakatsuki and Bianchini described the metal-assisted
coupling of an alkynyl and a vinylidene unit by using
dichlororuthenium(II) complexes as precursors.3,4
The orange, only moderately air-sensitive compound
2 reacts with tetravinyltin in the presence of CuCl to
give the [(2-4-η)-butadienyl]ruthenium(II) complex 3 in
about 70% yield. The structural proposal shown in
1
Scheme 1 is supported by the H and 13C NMR data,
The starting material [C5H5RuCl(dCdCHCO2Me)-
(PPh3)] (2) was obtained by stepwise treatment of the
allyl complex 15 with HCtCCO2Me and HCl in toluene/
benzene. The lability of the allyl-metal bond in 1 and
in the related compound [C5H5Ru(η3-C3H5)(CO)] in the
presence of acids has already been illustrated by us6 as
well as by Green7 and used for the synthesis of neutral
as well as cationic C5H5Ru complexes.
which are in good agreement with those of similar [(2-
4-η)-butadienyl]metal compounds.2,8 Like other C5H5-
(PPh3)Ru derivatives containing a η3-allyl ligand in the
exo configuration (i.e., with the central CH unit of the
allyl group pointing toward the C5H5 plane), the 1H
NMR spectrum of 3 displays a signal for the proton H3
at the terminal allylic carbon atom at δ 1.79 (doublet of
doublets) with a much larger P-H coupling (13.5 Hz)
than expected for the endo isomer.9 As far as the
stereochemistry at the noncoordinated CdC bond of the
butadienyl ligand is concerned, we assume that the CO2-
Me substituent is directed away from the metal (i.e.
trans disposed), as has also been found by X-ray
diffraction studies of [C5H5Ru(η3-CHRCRCdCHPh)-
X Abstract published in Advance ACS Abstracts, August 15, 1996.
(1) Vinylidene Transition-Metal Complexes 40. Part 39: Martin, M.;
Gevert, O.; Werner, H. J . Chem. Soc., Dalton Trans. 1996, 2275-2283.
(2) Wiedemann, R.; Wolf, J .; Werner, H. Angew. Chem. 1995, 107,
1359-1361; Angew. Chem., Int. Ed. Engl. 1995, 34, 1244-1246.
(3) Wakatsuki, Y.; Yamazaki, H.; Kumegawa, N.; Satoh, T.; Satoh,
J . Y. J . Am. Chem. Soc. 1991, 113, 9604-9610.
(4) Bianchini, C.; Innocenti, P.; Peruzzini, M.; Romerosa, A.; Zano-
bini, F. Organometallics 1996, 15, 272-285.
(5) Lehmkuhl, H.; Mauermann, H. J ustus Liebigs Ann. Chem. 1980,
754-767.
(6) Daniel, T.; Mahr, N.; Braun, T.; Werner, H. Organometallics
1993, 12, 1475-1477.
(8) Benyunes, S. A.; Deeth, R. J .; Fries, A.; Green, M.; McPartlin,
M.; Nation, C. B. M. J . Chem. Soc., Dalton Trans. 1992, 3453-3465
and references therein.
(9) Braun, T.; Gevert, O.; Werner, H. J . Am. Chem. Soc. 1995, 117,
7291-7292.
(7) Benyunes, S. A.; Day, J . P.; Green, M.; Al-Saadoon, A. W.;
Waring, T. L. Angew. Chem. 1990, 102, 1505-1507; Angew. Chem.,
Int. Ed. Engl. 1990, 29, 1416-1418.
S0276-7333(96)00390-1 CCC: $12.00 © 1996 American Chemical Society

4076 Organometallics, Vol. 15, No. 19, 1996
Notes
Sch em e 2
Sch em e 3
(PPh3)] (R ) CO2Me)10 and [RuCl(η3-CHRCHCdCHR′)-
(CO)(PPh3)2] (R ) R′ ) SiMe3; R ) Et, R′ ) tBu),11
respectively.
For the description of the bonding mode of the
butadienyl unit to the metal, probably more than one
resonance formula should be considered. Besides the
usual allyl-type coordination (see A in Scheme 2), a η1:
η2-butadienyl as well as a η2(3e)-vinylcarbene structure
(B and C) are conceivable and would explain the
chemical shift at δ 199.6 of the 13C NMR signal for the
quaternary carbon atom C2.12 The reason why we, in
contrast to Wakatsuki et al., favor the carbene-type
structure C instead of B is that in the 1H NMR spectrum
the signal of the proton H2 (for assignment, see the
Experimental Section) is observed at δ 2.88, while in
the crystallographically characterized complex [RuCl-
{η3-CH(SiMe3)CHC)CHSiMe3}(CO)(PPh3)2] it appears
at 5.39.11 An analogous bonding mode to that in C has
also been proposed by Green for [C5H5Mo{η2-)C(Ph)-
C)CHPh}{P(OMe)3}2] in order to explain the chemical
shift of the signal for the carbene carbon atom at δ 253.13
The allenylidene complex 4, which was prepared from
[C5Me5RuCl{κ2(P,O)-iPr2PCH2CO2Me}] and HCtCCPh2-
OH,14 also undergoes a CsC coupling reaction with a
vinyl unit. Treatment of a solution of 4 in benzene with
a solution of CH2dCHMgBr in THF led to a rapid
change of color from red to yellow and finally to the
isolation of yellow microcrystals of 5 in good yield. Since
the IR spectrum of 5 indicates that the functionalized
phosphine is only attached via phosphorus to the metal,
a η3-allyl bonding mode can be assumed for the
pentatrienyl ligand. The 13C NMR spectrum of 5
displays two low-field signals for the allene-like carbon
atoms C1 and C2 at δ 105.0 and 198.0 and three
resonances (each split into a doublet) for the allyl
carbons C3-C5 at δ 109.2, 54.3, and 34.7, respectively.
These data are quite similar to those found for the
pentatrienylrhodium complex [Rh{(3-5-η)-CH2CH-
C)CdCPh2)}(PiPr3)2]2 and, together with the data of
the 1H NMR spectrum of 5, leave no doubt that the
structural proposal shown in Scheme 3 is correct.
With regard to the mechanism of formation of the η3-
allyl-type compounds 3 and 5, we assume that initially
a nucleophilic substitution of the chloro ligand takes
place and a vinylmetal intermediate is generated. This
could rearrange by migratory insertion of the vinylidene
or allenylidene unit into the RusCHdCH2 bond to give
the final product. In this context it is important to note
that the rhodium complexes trans-[RhCl(dCdCHR)-
(PiPr3)2] (R ) tBu, Ph) react with CH2dCHMgBr to
yield the isolable intermediates trans-[Rh(CHdCH2)-
(dCdCHR)(PiPr3)2], which upon heating to 45-50 °C
in benzene isomerize to give almost quantitatively the
butadienyl derivatives [Rh{(2-4-η)-CH2CHCdCHR}-
(PiPr3)2].2 An alternative pathway leading to 3 and 5,
namely the addition of the vinyl nucleophile to the
R-carbon atom of the vinylidene or allenylidene ligand
followed by elimination of chloride with concomitant η1
to η3 rearrangement, could also be considered but seems
less likely.
Since compound 2 does not react with Sn(CHdCH2)4
in the absence of CuCl, this electrophilic substrate seems
to play a crucial role in the formation of 3. Although it
is possible that copper(I) chloride adds to the RudC
bond of 2 to activate the vinylidene unit,15 we assume
that CuCl interacts with the ruthenium-bonded chloride
and thus supports the substitution process. Lewis et al.
have recently shown that mono- and polynuclear alkyn-
ylruthenium complexes are accessible from the cor-
responding chlorometal precursors and SnMe3-substi-
tuted alkynes and diynes, but only in the presence of
CuI.16
Exp er im en ta l Section
All experiments were carried out under an atmosphere of
argon by using Schlenk tube techniques. The starting materi-
als 14 and 414 were prepared as described in the literature.
Melting points were determined by DTA. IR spectra were
measured with Perkin-Elmer 1420 and NMR spectra with
Bruker AC 200 and AMX 400 instruments.
P r ep a r a tion of [C5H5Ru Cl(dCdCHCO2Me)(P P h 3)] (2).
A solution of 1 (176 mg, 0.36 mmol) in 5 mL of toluene was
treated with HCtCCO2Me (158 µL, 1.82 mmol). A 0.16 M
solution of HCl (2.76 mL, 0.44 mmol) in benzene was added,
and the reaction mixture was stirred for 5 min at room
temperature. After the solvent was removed, the residue was
(10) Bruce, M. I.; Catlow, A.; Cifuentes, M. P.; Snow, M. R.; Tiekink,
E. R. T. J . Organomet. Chem. 1990, 397, 187-202.
(11) Wakatsuki, Y.; Yamazaki, H.; Maruyama, Y.; Shimizu, I. J .
Organomet. Chem. 1992, 430, C60-C63.
(12) For comparison see: Hofmann, P.; Ha¨mmerle, M.; Unfried, G.
New J . Chem. 1991, 15, 769-789.
(15) (a) Werner, H.; Wolf, J .; Mu¨ller, G.; Kru¨ger, C. J . Organomet.
Chem. 1988, 342, 381-398. (b) Werner, H.; Weinand, R.; Knaup, W.;
Peters, K.; von Schnering, H. G. Organometallics 1991, 10, 3967-3977.
(16) Khan, M. S.; Kakkar, A. K.; Ingham, S. L.; Raithby, P. R.; Lewis,
J .; Spencer, B.; Wittmann, F.; Friend, R. H. J . Organomet. Chem. 1994,
472, 247-255.
(13) Feher, F. J .; Green, M.; Rodrigues, R. A. J . Chem. Soc., Chem.
Commun. 1987, 1206-1208.
(14) Braun, T.; Steinert, P.; Werner, H. J . Organomet. Chem. 1995,
488, 169-176.

Notes
Organometallics, Vol. 15, No. 19, 1996 4077
washed twice with 5 mL of pentane. An orange microcrystal-
line solid was obtained: yield 184 mg (94%); mp 134 °C dec.
Anal. Calcd for C27H24ClO2PRu: C, 59.18; H, 4.41. Found:
After the solvent was removed, the residue was extracted with
3 mL of benzene and the extract was brought to dryness in
vacuo. A yellow solid was obtained, which was washed with
2 mL of pentane at 0 °C and dried in vacuo: yield 46 mg (68%);
mp 76 °C dec. Anal. Calcd for C36H47O2PRu: C, 67.16; H,
7.36. Found: C, 67.30; H, 7.56. IR (THF): ν(CdCdC) 1930,
C, 59.42; H, 4.46. IR (KBr): ν(CdO) 1680, ν(CdC) 1580 cm-1
.
1H NMR (400 MHz, C6D6): δ 7.73, 6.99 (both m, 15H, C6H5),
5.04 (s, 5H, C5H5), 4.48 (s, 1H, dCHCO2CH3), 3.33 (s, 3H, CO2-
CH3). 13C NMR (100.6 MHz, C6D6): δ 335.3 (d, J (PC) ) 22.8
Hz, RudC), 166.3 (s, CO2CH3), 139.4 (d, J (PC) ) 39.5 Hz, i-C
of C6H5), 134.2 (d, J (PC) ) 10.3 Hz, o-C of C6H5), 130.5 (d,
J (PC) ) 2.0 Hz, p-C of C6H5), 128.3 (d, J (PC) ) 10.4 Hz, m-C
of C6H5), 109.0 (s, dCHCO2CH3), 93.4 (s, C5H5), 50.6 (s,
CO2CH3). 31P NMR (81.0 MHz, C6D6): δ 54.3 (s).
ν(CdO) 1720 cm-1
.
P r ep a r a tion of [C5H5Ru {(2-4-η)-CH2CHCdCHCO2Me}-
(P P h 3)] (3). A solution of 2 (220 mg, 0.40 mmol) in 10 mL of
THF was treated with Sn(CHdCH2)4 (0.50 mL, 2.75 mmol)
and CuCl (2.0 mg, 0.02 mmol). The reaction mixture was
heated for 3 h to 60 °C, and upon cooling to 25 °C, the solution
was brought to dryness in vacuo. The residue was dissolved
in 10 mL of ethanol, and the mixture was stirred for 1 h at
room temperature. The solvent was removed, the residue was
extracted with 2 mL of toluene, and the solution was chro-
matographed on Al2O3 (basic, activity grade V, length of
column 6 cm). With toluene, a yellow fraction was eluted, from
which the solvent was removed in vacuo. The residue was
washed with 2 mL of pentane to give a yellow microcrystalline
solid: yield 145 mg (67%); mp 125 °C dec. Anal. Calcd for
1H NMR (400 MHz, C6D6): δ 7.76 (d, J (HH) ) 7.4 Hz, 2H,
o-H of C6H5), 7.45 (d, J (HH) ) 7.2 Hz, 2H, o-H of C6H5), 7.25,
7.08, 6.70 (all m, 6H, C6H5), 3.18 (s, 3H, OCH3), 2.92 (ddd,
J (PH) ) 2.9, J (H1H3) ) 8.8, J (H1H2) ) 7.2 Hz, 1H, H1), 2.27
(dsept, J (PH) ) 2.6, J (HH) ) 6.9 Hz, 1H, PCHCH3), 2.05 (dd,
J (H1H2)) 7.1, J (H2H3) ) 2.1 Hz, 1H, H2), 2.00 (sept, J (HH) )
7.1 Hz, 1H, PCHCH3), 1.87 (part of an ABX pattern, d in 1H-
{31P}, J (HH) ) 14.0 Hz, 1H, PCH2), 1.81 (part of an ABX
pattern, d in 1H{31P}, J (HH) ) 14.0 Hz, 1H, PCH2), 1.59 (d,
J (PH) ) 0.8 Hz, 15H, C5Me5), 1.13 (dd, J (PH) ) 14.6, J (HH)
) 6.6 Hz, 3H, PCHCH3), 1.08 (dd, J (PH) ) 15.2, J (HH) ) 7.1
Hz, 3H, PCHCH3), 1.01 (dd, J (PH) ) 15.2, J (HH) ) 7.1 Hz,
3H, PCHCH3), 0.97 (dd, J (PH) ) 11.0, J (HH) ) 6.9 Hz, 3H,
PCHCH3), signal of H3 covered by the singlet of the C5Me5
protons. 13C NMR (100.6 MHz, C6D6): δ 190.0 (d, J (PC) )
13.1 Hz, C2), 170.9 (d, J (PC) ) 9.4 Hz, CO2CH3), 141.0 (s, J (PC)
) 42.6 Hz, i-C of C6H5), 129.6, 128.5, 128.3, 128.0, 125.7, 125.5
(all s, C6H5), 109.2 (d, J (PC) ) 12.7 Hz, C3), 105.0 (s, C1), 90.6
(s, C5Me5), 54.3 (d, J (PC) ) 2.1 Hz, C4), 50.9 (s, CO2CH3), 34.7
(d, J (PC) ) 6.3 Hz, C5), 28.3 (d, J (PC) ) 20.2 Hz, PCHCH3),
28.1 (d, J (PC) ) 10.5 Hz, PCH2), 26.6 (d, J (PC) ) 20.3 Hz,
PCHCH3), 20.0 (d, J (PC) ) 3.3 Hz, PCHCH3), 18.5 (d, J (PC)
) 4.7 Hz, PCHCH3), 16.8 (d, J (PC) ) 6.5 Hz, PCHCH3), 10.8
(s, C5Me5). 31P NMR (162.0 MHz, C6D6): δ 63.4 (s).
C
29H27O2PRu: C, 64.55; H, 5.04. Found: C, 64.08; H, 4.85.
IR (C6H6): ν(CdO) 1695 cm-1
.
1H NMR (400 MHz, C6D6): δ 7.67, 7.43, 7.01 (all m, 15H, C6H5),
6.79 (dd, J (PH) ) 2.8, J (H1H4) ) 1.6 Hz, 1H, H4), 4.46 (s, 5H,
C5H5), 3.50 (s, 3H, CO2CH3), 3.40 (m, 1H, H1), 2.88 (d, J (H1H2)
) 7.1 Hz, 1H, H2), 1.79 (dd, J (PH) ) 13.5, J (H1H3) ) 9.8 Hz,
1H, H3). 13C NMR (100.6 MHz, C6D6): δ 199.6 (d, J (PC) )
13.1 Hz, C2), 169.5 (s, CO2CH3), 137.5 (d, J (PC) ) 42.6 Hz,
i-C of C6H5), 134.5 (d, J (PC) )10.5 Hz, o-C of C6H5), 129.2 (s,
p-C of C6H5), 127.6 (d, J (PC) ) 9.7 Hz, m-C of C6H5), 110.8 (d,
J (PC) ) 5.7 Hz, C1), 82.6 (s, C5H5), 50.0 (s, CO2CH3), 42.3 (s,
C3), 33.4 (d, J (PC) ) 4.4 Hz, C4). 31P NMR (162.0 MHz,
C6D6): δ 58.7 (s).
P r ep a r a tion of [C5H5Ru (3-5-η)-CH2CHCdCdCP h 2}-
(P P h 3)] (5). A solution of 4 (69 mg, 0.11 mmol) in 5 mL of
benzene was treated with a 0.75 M solution of CH2dCHMgBr
(157 µL, 0.11 mmol) in THF and stirred for 5 min at room
temperature. A change of color from red to yellow occurred.
Ack n ow led gm en t . We thank the Deutsche For-
schungsgemeinschaft (Grant No. SFB 347), the Volks-
wagen Stiftung, and the Fonds der Chemischen Indu-
strie for financial support. We also gratefully acknowl-
edge support by Mrs. R. Schedl and C. P. Kneis
(elemental analysis and DTA), Mrs. K. Manger (techni-
cal assistance), B. Stempfle (NMR measurements), and
Degussa AG (chemicals).
OM960390R