Ruthenium vinylidene and σ-acetylide complexes containing 1,4,7-trimethyl-1,4,7-triazacyclononane (Me3tacn): Synthesis and alkyne-coupling reactivity

Article abstract of DOI:10.1021/om970046+

The ruthenium(II) complexes [Ru(Me₃tacn)(L)₂X]PF₆ (L = PMe₃, X = O₂CCF₃ (1a); L = PMe₃, X = Cl (1b); L = 1/2 dmpe, X = O₂CCF₃ (1c)) are prepared. Only 1a reacts with 1 equiv of RC≡CH (R = Ph and p-tolyl) to give the vinylidene complexes [Ru(Me₃tacn)-(PMe₃)(O₂CCF ₃){C=CH(R)}]PF₆ (R=Ph (2a) and p-tolyl (2b)) in refluxing 1,2-dichloroethane. Reaction of 2a and 2b with PMe₃ in methanolic KOH solution give the corresponding σ-acetylide complexes [Ru(Me₃tacn)(PMe₃)₂(C≡CR)]PF₆ (R=Ph (3a) and p-tolyl (3b)). Similarly, treatment of 2a with P(OMe₃)₃ affords [Ru(Me₃tacn)(PMe₃)(P(OMe) ₃)(C≡CPh)]-PF₆ (3c). Oxidative cleavage of the vinylidene ligand in 2a by oxygen gives [Ru(Me₃tacn)-(PMe₃)(O₂CCF ₃)(CO)]PF₆ (4) and benzaldehyde. Complex 1b reacts with 2.5 equiv of RC≡CH (R=Ph, p-tolyl) and 1.5 equiv of KOH in methanol to yield the η³-butenynyl species [Ru(Me₃-tacn)(PMe₃){η³-RC ₃=CH(R)}]PF₆ (R = Ph (5a) and p-tolyl (5b)). In addition, 2a and 2b react with RC≡CH (R = Ph, p-tolyl) and KOH in methanol to give 5a and 5b, respectively. Treatment of 2a with p-tolylC≡CH and KOH in methanol gives [(Me₃tacn)Ru(PMe₃){/73-PhC ₃=CH(p-tolyl)}]PF₆ (5c) and [(Me₃tacn)Ru(PMe₃){η ³-(p-tolyl)C3=CH(Ph)}]PF₆ (5c′) in a 1:1 ratio. Reacting 2b with PhC≡CH similarly gives 5c and 5c′ in equal amounts. Structures of 3c, 5a, and 5c/5c′ are established by X-ray crystallography. Mechanistic insights from the isolated complexes suggest that hydrogen shift between vinylidene and acetylide moieties is an important process in the coupling of alkynes.

Full text of DOI:10.1021/om970046+

Organometallics 1997, 16, 2819-2826
2819
Ru th en iu m Vin ylid en e a n d σ-Acetylid e Com p lexes
Con ta in in g 1,4,7-Tr im eth yl-1,4,7-tr ia za cyclon on a n e
(Me3ta cn ): Syn th esis a n d Alk yn e-Cou p lin g Rea ctivity
San-Ming Yang,† Michael Chi-Wang Chan,† Kung-Kai Cheung,†
Chi-Ming Che,*,† and Shie-Ming Peng‡
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, and
Department of Chemistry, National Taiwan University, Taiwan
Received J anuary 24, 1997X
The ruthenium(II) complexes [Ru(Me3tacn)(L)2X]PF6 (L ) PMe3, X ) O2CCF3 (1a ); L )
1
PMe3, X ) Cl (1b); L ) /2 dmpe, X ) O2CCF3 (1c)) are prepared. Only 1a reacts with 1
equiv of RCtCH (R ) Ph and p-tolyl) to give the vinylidene complexes [Ru(Me3tacn)-
(PMe3)(O2CCF3){CdCH(R)}]PF6 (R ) Ph (2a ) and p-tolyl (2b)) in refluxing 1,2-dichloroethane.
Reaction of 2a and 2b with PMe3 in methanolic KOH solution give the corresponding
σ-acetylide complexes [Ru(Me3tacn)(PMe3)2(CtCR)]PF6 (R ) Ph (3a ) and p-tolyl (3b)).
Similarly, treatment of 2a with P(OMe3)3 affords [Ru(Me3tacn)(PMe3)(P(OMe)3)(CtCPh)]-
PF6 (3c). Oxidative cleavage of the vinylidene ligand in 2a by oxygen gives [Ru(Me3tacn)-
(PMe3)(O2CCF3)(CO)]PF6 (4) and benzaldehyde. Complex 1b reacts with 2.5 equiv of RCtCH
(R ) Ph, p-tolyl) and 1.5 equiv of KOH in methanol to yield the η3-butenynyl species [Ru(Me3-
tacn)(PMe3){η3-RC3dCH(R)}]PF6 (R ) Ph (5a ) and p-tolyl (5b)). In addition, 2a and 2b
react with RCtCH (R ) Ph, p-tolyl) and KOH in methanol to give 5a and 5b, respectively.
Treatment of 2a with p-tolylCtCH and KOH in methanol gives [(Me3tacn)Ru(PMe3){η3-
PhC3dCH(p-tolyl)}]PF6 (5c) and [(Me3tacn)Ru(PMe3){η3-(p-tolyl)C3dCH(Ph)}]PF6 (5c′) in a
1:1 ratio. Reacting 2b with PhCtCH similarly gives 5c and 5c′ in equal amounts. Structures
of 3c, 5a , and 5c/5c′ are established by X-ray crystallography. Mechanistic insights from
the isolated complexes suggest that hydrogen shift between vinylidene and acetylide moieties
is an important process in the coupling of alkynes.
Reports on the reactivity of transition metal vinyl-
idene and acetylide complexes demonstrate a close
relationship between these organometallic interactions.1
Their interconversions are important in the dimeriza-
tion of alkynes2 and condensation of alkynes with allylic
alcohols3 or carboxylic acids.4 Many d6 metal vinylidene
complexes have been prepared by reaction of appropri-
ate metal precursors with 1-alkynes.5 Theoretical stud-
ies suggest that initial side-on coordination of the
1-alkyne is followed by a 1,2-hydrogen shift to give the
metal vinylidene complex.6,7 This usually spontaneous
rearrangement is driven by a repulsive interaction
between the filled π orbital of the alkyne and the filled
dπ(t2g) metal orbital.8 However, Selegue and Bullock
reported that this rearrangement can require thermal
initiation.9 Recently, 1,2-hydrogen shift initiated by an
electron transfer pathway was published.10
Ruthenium vinylidene complexes containing “soft”
ligands11 such as η-cyclopentadienyl,12 η-benzene,13 bis-
(diphenylphosphino)methane,14 and CH3(CH2)2N(CH2-
CH2PPh2)215 have been synthesized. However, since the
unfavorable π-interaction between the dπ(Ru) and
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Chem. Soc. 1994, 116, 8105.
(8) (a) Templeton, J . L. Adv. Organomet. Chem. 1989, 29, 1. (b)
Kostic, N. M.; Fenske, R. F. Organometallics 1982, 1, 974.
(9) (a) Lomprey, J . R.; Selegue, J . P. J . Am. Chem. Soc. 1992, 114,
5518. (b) Bullock, R. M. J . Chem. Soc., Chem. Commun. 1989, 165.
(10) Connelly, N. G.; Geiger, W. R.; Lagunas, M. C.; Metz, B.; Rieger,
A. L.; Reiger, P.H.; Shaw, M. J . J . Am. Chem. Soc. 1995, 117, 12202.
(11) Pearson, R. G. Hard and Soft Acids and Bases; Dowden,
Hutchinson, and Ross: Stroudsburg, PA, 1973.
(12) (a) Bruce, M. I.; Wallis, R. C. Aust. J . Chem. 1979, 32, 1471.
(b) Bruce, M. I.; Wallis, R. C. J . Organomet. Chem. 1978, 161, C1.
(13) (a) Le Bozec, H.; Ouzzine, K.; Dixneuf, P. H. Organometallics
1991, 10, 2768. (b) Dixneuf, P. H. Pure Appl. Chem. 1989, 61, 1763.
(14) (a) Touchard, D.; Haquette, P.; Pirio, N.; Toupet, L.; Dixneuf,
P. H. Organometallics 1993, 12, 3132. (b) Haquette, P.; Pirio, N.;
Touchard, D.; Toupet, L.; Dixneuf, P. H. J . Chem. Soc., Chem.
Commun. 1993, 163.
† The University of Hong Kong.
‡ National Taiwan University.
X Abstract published in Advance ACS Abstracts, May 15, 1997.
(1) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197. (b) Antonova, A. B.;
Ioganson, A. A. Russ. Chem. Rev. 1989, 58, 593. (c) Bruce, M. I.;
Swincer, A. G. Adv. Organomet. Chem. 1983, 22, 59.
(2) (a) Yi, C. S.; Liu, N. H. Organometallics 1996, 15, 3968. (b)
Bianchini, C.; Innocenti, P.; Peruzzini, M.; Romerosa, A.; Zanobini, F.;
Frediani, P. Organometallics 1996, 15, 272. (c) Matsuzaka, H.; Takagi,
Y.; Ishii, Y.; Nishio, M.; Hidai, M. Organometallics 1995, 14, 2153. (d)
Barbaro, P.; Bianchini, C.; Peruzzini, M.; Polo, A.; Zanobini, F. Inorg.
Chim. Acta 1994, 220, 5. (e) Bianchini, C.; Frediani, P.; Masi, D.;
Peruzzini, M.; Zanobini, F. Organometallics 1994, 13, 4616. (f) Ducha-
teau, R.; van Wee, C. T.; Meetsma, A.; Teuben, J . H. J . Am. Chem.
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Frediani, P.; Albinati, A. J . Am. Chem. Soc. 1991, 113, 5453.
(3) (a) Dien, S.; Dixneuf, P. H. J . Chem. Soc., Chem. Commun. 1994,
2551. (b) Trost, B. M.; Martinez, J . A.; Kulawiec, R. J .; Indolese, A. F.
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Am. Chem. Soc. 1992, 114, 5579. (d) Trost, B. M.; Dyker, G.; Kulawiec,
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(4) (a) Doucet, H.; Martin-Vaca, B.; Bruneau, C.; Dixneuf, P. H. J .
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S0276-7333(97)00046-0 CCC: $14.00 © 1997 American Chemical Society

2820 Organometallics, Vol. 16, No. 13, 1997
Yang et al.
mixture was refluxed for 18 h. The zinc powder was removed,
and upon addition of NH4PF6, a yellow solid was formed. The
solid was filtered, washed with ethanol, water, and diethyl
ether, and air-dried (yield ) 0.10 g, 63%). Anal. Calcd for
π (CtC) orbitals is the driving force for the alkyne-
vinylidene rearrangement, we anticipated that synthe-
sis of vinylidene complexes may be achieved by utilizing
“hard” amine ligand systems. However, reaction be-
tween [Ru(NH3)5(H2O)]2+ and phenylacetylene yielded
C
15H39N3ClF6P3Ru: C, 29.78 ; H, 6.49; N, 6.95. Found: C,
29.95; H, 6.38; N, 6.85. 1H NMR (500 MHz, CD3CN): 1.49
(18H, virtual t, J PH ) 3.7 Hz, P(CH3)3), 2.66-3.13 (21H, m,
Me3tacn). 31P{1H} NMR (CD3CN): -1.0. FAB mass spec-
trum: m/ z 460 [M+ - PF6], 384 [M+ - PF6 - PMe3].
[Ru (Me3ta cn )(d m p e)(O2CCF 3)]P F 6 (1c). Compared to
1a , the titled compound was prepared using dmpe instead of
PMe3 (yield ) 0.19 g, 41%). Anal. Calcd for C17H37N3O2F9P3-
Ru: C, 30.00; H, 5.48; N, 6.18. Found: C, 30.05; H, 5.60; N,
6.15. 1H NMR (300 MHz, (CD3)2CO): 1.42 (6H, d, J ) 9 Hz,
P-CH3), 1.71 (6H, d, J PH ) 7.62 Hz, P-CH3), 2.67 (3H, s,
N-CH3), 2.73-3.37 (22H, m, 2 × N-CH3, N-CH2, P-CH2). IR
(cm-1): ν(CO) 1685. 31P{1H} NMR (CD3CN): 42.9. FAB mass
spectrum: m/ z 536 [M+ - PF6].
the η2-alkyne complex [Ru(NH3)5(η2-PhCtCH)]2+ 16
.
We have been studying the chemistry of organo-
ruthenium complexes containing the saturated tertiary
amine 1,4,7-trimethyl-1,4,7-triazacyclononane.17,18 In
this work, ruthenium vinylidene and σ-acetylide deriva-
tives are prepared, and reactions of the former with base
and oxygen are studied. Coupling reactions with
1-alkynes resulting in carbon-carbon bond formation
are observed.
Exp er im en ta l Section
[R u (Me3t a cn )(P Me3)(O2CCF 3){CdCH (P h )}]P F 6 (2a ).
Complex 1a (0.20 g, 0.29 mmol) and PhCtCH (0.03 g, 0.29
mmol) were mixed in 1,2-dichloroethane (20 cm3). The solution
was refluxed for 2 h to give a red solution. The solvent was
removed, and a methanolic solution of NH4PF6 was added to
afford a red crystalline solid (yield ) 0.18 g, 87%). Anal. Calcd
for C22H36N3O2F9P2Ru: C, 37.29; H, 5.12; N, 5.93. Found: C,
37.38; H, 5.12; N, 5.74. IR (cm-1): ν(CO) 1710 (m); ν(CdC)
All reactions were carried out in a nitrogen atmosphere
using standard Schlenk techniques unless otherwise stated.
Ru(Me3tacn)Cl3 and [Ru(Me3tacn)(OH2)2(O2CCF3)](OTf)2
19
20
(OTf ) trifluoromethanesulfonate) were prepared according
to the published methods. Trimethylphosphine and 1,2-bis-
(dimethylphosphino)ethane (dmpe) were purchased from
Merck and used as received. PhCtCH and p-tolylCtCH were
obtained from Aldrich and distilled before use. All solvents
were reagent grade and used without further purification.
1621 (m). 1H NMR (270 MHz, (CD3)2CO): 1.59 (9H, d, J PH
)
9.25 Hz, P(CH3)3), 3.25-3.65 (21H, m, Me3tacn), 5.47 (1H, d,
J PH ) 4.39 Hz, dCH(Ph)), 7.14-7.46 (m, 5H, C6H5). 13C{1H}
NMR (270 MHz, CD2Cl2): 363.7 (d, J PC ) 22.3 Hz, RudCdC),
129.4, 128.3, 127.7, 126.9 (C6H5), 117.3, 112.9 (CF3CO2), 111.6
(RudCdC), 63.6, 63.2, 61.4, 60.3, 59.5, 58.2, 56.5, 52.0, 51.7
(Me3tacn), 16.3 (d, J PC ) 30.9 Hz, P(CH3)3). 31P{1H} NMR
(CD3CN): -3.0. FAB mass spectrum: m/ z 564 [M+ - PF6],
462 [M+ - PF6 - PhCtCH].
1
13C{1H} and H NMR spectra were recorded on a J EOL 270
FT-NMR, Bruker 300 DPX FT-NMR, or Bruker 500 DRX FT-
NMR spectrometer operating at 270, 300, or 500 MHz (1H)
and 67.5, 75, or 125 MHz (13C), respectively. Peak positions
were calibrated with Me4Si as internal standard. 31P{1H}
NMR spectra were recorded on the Bruker 500 DRX FT-NMR
spectrometer operating at 202.4 MHz, and chemical shifts were
measured relative to external 85% H3PO4 with downfield
values taken as positive. Fast atom bombardment (FAB) mass
spectra were obtained on a Finnigan MAT 95 mass spectrom-
eter with 3-nitrobenzyl alcohol matrix. Infrared spectra were
recorded as Nujol mulls on a BIO RAD FT-IR spectrometer
between KBr plates. Elemental analyses were performed by
the Butterworth Laboratory Ltd, U.K.
[Ru (Me3tacn )(P Me3)(O2CCF3){CdCH(p-tolyl)}]P F6 (2b).
The procedure was similar to 2a except p-tolylCtCH was used
instead of PhCtCH (yield ) 0.10 g, 50%). Anal. Calcd for
C
23H38N3O2F9P2Ru: C, 38.17; H, 5.26; N, 5.81. Found: C,
37.96, H, 5.52; N, 5.94. IR (cm-1): ν(CO) 1715 (m); ν(CdC)
1635 (m). 1H NMR (500 MHz, (CD3)2CO): 1.63 (9H, d, J PH
)
9.6 Hz, P(CH3)3), 2.30 (3H, s, C6H4CH3), 3.02-3.87 (21H, m,
Me3tacn), 5.13 (1H, d, J PH ) 4.45 Hz, dCH(p-tolyl)), 7.04-
7.13 (dd, 4H, C6H4). 13C{1H} NMR (125 MHz, (CD3)2CO):
362.9 (d, J PC ) 23.3 Hz, RudCdC), 130.2, 130.1, 127.9, 126.7
(C6H4), 110.8 (RudCdC), 63.8, 57.7, 58.7, 60.1, 61.2, 61.3, 63.2,
52.6 (Me3tacn), 21.1 (C6H4CH3), 17.1 (d, J PC ) 32.6 Hz,
P(CH3)3). 31P{1H} NMR ((CD3)2CO): -3.8. FAB mass spec-
trum: m/ z 578 [M+ - PF6], 462 [M+ - PF6 - p-tolylCtCH].
[Ru (Me3ta cn )(P Me3)2(CtCP h )]P F 6 (3a ). PMe3 (0.10 g,
1.3 mmol) and potassium hydroxide (0.10 g, 1.8 mmol) were
dissolved in anhydrous methanol (10 cm3). Complex 2a (0.10
g, 0.14 mmol) was then added, and the mixture was stirred
for 2 h to give a yellow solution. The methanol was removed
under reduced pressure. The residue was then dissolved in
acetone, and a saturated aqueous solution of NH4PF6 was
added. Slow evaporation of acetone gave a yellow crystalline
solid (yield ) 0.05 g, 53%). Anal. Calcd for C23H44N3F6P3Ru:
C, 41.19: H, 6.61; N, 6.27. Found: C, 40.91; H, 6.53; N, 6.10.
IR (cm-1): ν(CtC) 2065. 1H NMR (500 MHz, (CD3)2CO): 1.64
(18H, virtual t, J PH ) 3.7 Hz, P(CH3)3), 2.75-3.34 (21H, m,
Me3tacn), 6.95-7.00 (1H, m, para H), 7.11-7.19 (4H, m, ortho
and meta H). 13C{1H} NMR (125 MHz, (CD3)2CO): 131.3,
130.9, 128.7, 124.1 (C6H5), 131.0 (t, J PC ) 10 Hz, Ru-CtC),
108.9 (Ru-CtC), 62.5, 61.7, 60.1, 58.2, 55.4 (Me3tacn), 21.9
(virtual t, J PC ) 14.5 Hz, P(CH3)3). 31P{1H} NMR ((CD3)2CO):
-0.5. FAB mass spectrum: m/ z 538 [M+ - PF6], 462 [M+
2.4. FAB mass spectrum: m/ z 526 [M+ - PF6], 450 [M+
PF6 - PMe3].
-
[R u (Me3t a cn )(P Me3)2{CtC(p -t olyl)}]P F 6 (3b ). Com-
pared to 3a , 2b was used instead of 2a as starting material
(yield ) 0.04 g, 42%). Anal. Calcd for C24H46N3F6P3Ru: C,
42.10; H, 6.77; N, 6.14. Found: C, 41.95; H, 6.41; N, 5.98. IR

Ruthenium Vinylidene and σ-Acetylide Complexes
Organometallics, Vol. 16, No. 13, 1997 2821
(cm-1): ν(CtC) 2065. 1H NMR (270 MHz, CD3CN): 1.51 (18H,
virtual t, J PH ) 3.8 Hz, P(CH3)3), 2.24 (3H, s, C6H4CH3), 2.66-
3.19 (21H, m, Me3tacn), 6.94-7.05 (4H, dd, C6H4). 13C{1H}
NMR (67.5 MHz, CD3CN): 133.9, 130.9, 129.7, 128.4 (C6H4),
108.5 (Ru-CtC), 62.4, 61.7, 60.0, 58.3, 55.5 (Me3tacn), 21.9
(virtual t, J PC ) 14.5 Hz, P(CH3)3), 21.2 (C6H4CH3), Ru-CtC
not resolved. 31P{1H} NMR (CD3CN): 2.4. FAB mass spec-
trum: m/ z 540 [M+ - PF6], 464 [M+ - PF6 - PMe3].
[Ru (Me3ta cn )(P Me3)(P (OMe)3)(CtCP h )]P F 6 (3c). Com-
pared to 2a , P(OMe)3 was used instead of PMe3 (yield ) 0.06
g, 55%). Anal. Calcd for C23H44N3O3F6P3Ru: C, 38.43; H, 6.17;
N, 5.85. Found: C, 38.31; H, 6.16; N, 5.87. IR (cm-1): ν(CtC)
2056. 1H NMR (270 MHz, (CD3)2CO): 1.57 (9H, d, J PH ) 8.6
Hz, P(CH3)3), 2.80-3.32 (21H, m, Me3tacn), 3.98 (9H, d, J PH
) 10.0 Hz, P(OCH3)3), 7.01-7.20 (5H, m, phenyl). 13C{1H}
NMR (270 MHz, (CD3)2CO): 130.9, 130.8, 128.8, 124.5 (C6H5),
110.1 (Ru-CtC), 62.9, 62.2, 61.2, 60.6, 60.4, 59.5, 57.5, 55.6,
54.2 (Me3tacn), 54.3 (d, J PC ) 10.4 Hz, P(OCH3)3), 20.8 (d, J PC
) 31.2 Hz, P(CH3)3), Ru-CtC not resolved. 31P{1H} NMR
s, N-CH3), 2.40-3.61 (15H, m, Me3tacn), 3.81 (3H, s, N-CH3),
6.94 (1H, s, H4), 7.21 (1H, t, J ) 7.3 Hz, H8′), 7.33 (1H, t, J )
7.4 Hz, H8), 7.39 (2H, t, J ) 7.6 Hz, H7), 7.44 (2H, t, J ) 7.5
Hz, H7’), 7.77 (2H, d, J ) 7.4 Hz, H6′), 7.82 (2H, d, J ) 7.4
Hz, H6). 13C{1H} NMR (125 MHz, CD2Cl2): 159.1 (d, J ) 7.6
Hz, C3), 138.2, 132.4, 130.8, 129.6, 129.3, 127.8, 126.2, 125.3
(2 × C6H5), 124.6 (d, J ) 6.1 Hz, C1), 123.2 (C4), 62.4, 61.6,
61.4, 59.8, 59.4, 58.9, 58.7, 58.4 (Me3tacn), 57.2 (d, J ) 1.5
Hz, C2), 47.8 (N-CH3), 16.7 (d, J ) 28.6 Hz, P(CH3)3). 31P{1H}
NMR (CD2Cl2): 4.8. FAB mass spectrum: m/ z 553 [M+
PF6], 477 [M+ - PF6 - PMe3].
-
[R u (Me3t a cn )(P Me3){η3-(p -t olyl)C3dCH (p -t olyl)}]P F 6
(5b). Compared to 5a , this complex was synthesized by
method A using p-tolylCtCH instead of PhCtCH or by
method B using complex 2b and p-tolylCtCH as the starting
materials (yield ) 0.09 g, 52%). Anal. Calcd for C30H45N3F6P2-
Ru: C, 49.72; H, 6.22; N, 5.80. Found: C, 49.52; H, 6.46; N,
5.65. 1H NMR (500 MHz, CD2Cl2): 0.93 (9H, d, J PH ) 7.9 Hz,
P(CH3)3), 1.61 (3H, s, N-CH3), 2.33 (3H, s, H9), 2.39 (3H, s,
H9′), 2.41-3.61 (15H, m, Me3tacn), 3.87 (3H, s, N-CH3), 6.88
(1H, s, H4), 7.20 (2H, d, J ) 7.9 Hz, H7), 7.26 (2H, d, J ) 7.9
Hz, H7′), 7.66 (2H, d, J ) 8.1 Hz, H6′), 7.72 (2H, d, J ) 8.1
Hz, H6). 13C{1H} NMR (125 MHz, CD2Cl2): 157.5 (d, J ) 7.6
Hz, C3), 138.1 (C8′), 136.1 (C8), 135.7 (C5), 130.7 (C6′), 130.3
(C7), 129.9 (C7′), 129.5 (C5′), 125.2 (C6), 123.8 (d, J ) 5.4 Hz,
C1), 122.7 (C4), 62.4, 61.6, 61.4, 59.8, 59.4, 58.9, 58.7, 58.4
(Me3tacn), 55.8 (d, J ) 1.6 Hz, C2), 47.7(N-CH3), 21.5(C9’),
21.3(C9), 16.7 (d, J ) 28.5 Hz, P(CH3)3). 31P{1H} NMR
(CD2Cl2): 5.2. FAB mass spectrum: m/ z 580 [M+ - PF6], 504
[M+ - PF6 - PMe3].
[Ru (Me3tacn )(P Me3){η3-P h C3dCH(p-tolyl)}]P F6 (5c) an d
[R u (Me3t a cn )(P Me3){η3-(p -t olyl)C3dCH (P h )}]P F 6 (5c′).
p-TolylCtCH was used in method B for 5a (yield ) 0.08 g,
48%). Anal. Calcd for C29H43N3F6P2Ru‚CH3OH: C, 48.51; H,
6.38; N, 5.66. Found: C, 48.22; H, 6.24; N, 5.57. 1H NMR
(500 MHz, CD2Cl2): 0.94 (18H, d, J PH ) 7.8 Hz, P(CH3)3), 1.62
(6H, s, N-CH3), 2.39 (3H, s, CH3 of p-tolyl), 2.45 (3H, s, CH3 of
p-tolyl), 2.50-3.59 (30H, m, Me3tacn), 3.87 (6H, s, N-CH3), 6.91
(1H, s, dCH), 6.93 (1H, s, dCH), 7.20-7.85 (18H, m, C6H5).
31P{1H} NMR (CD2Cl2): 5.0. FAB mass spectrum: m/ z 566
[M+ - PF6], 490 [M+ - PF6 - PMe3].
Str u ctu r a l Deter m in a tion . X-ray quality crystals were
obtained by slow diffusion of diethyl ether into an acetone
solution for 3c and a dichloromethane solution for 5a , respec-
tively. Intensities and lattice parameters were measured on
a Rigaku AFC7R or Enraf-Nonius CAD-4 diffractometer using
the ω-2θ scan mode. Crystal parameters and details of data
collection and refinement are given in Table 1. Intensity data
were corrected for Lorentz and polarization effects. Empirical
absorptions were based on the ψ-scan of five strong reflections.
The structures were solved by the heavy-atom Patterson
method and refined by full-matrix least squares and Fourier-
difference syntheses using the MSC-Crystal Structure Package
TEXSAN on a Silicon Graphic Indy computer.22 All non-H
atoms were refined anisotropically. The H atoms at calculated
positions with thermal parameters equal to 1.3 times that of
the attached C atoms were not refined. Selected bond dis-
tances and angles of 3c and 5a are tabulated in Tables 2 and
3, respectively.
((CD3)2CO): 137.6 (d, J PP ) 70.5 Hz, P(OMe)3), 3.2 (d, J PP
)
70.5 Hz, PMe3). FAB mass spectrum: m/ z 574 [M+ - PF6],
498 [M+ - PF6 - PMe3].
[Ru (Me3ta cn )(P Me3)(O2CCF 3)(CO)]P F 6 (4). Oxygen gas
was introduced into a 1,2-dichloroethane solution of 2a (0.08
g, 0.11 mmol) for 8 h. The color of the solution changed from
red-orange to yellow. The solution was then concentrated to
ca. 5 cm3 under reduced pressure. The titled compound was
isolated as a yellow solid upon addition of diethyl ether and
recrystallized from dichloromethane/diethyl ether (yield ) 0.03
g, 52%). Anal. Calcd for C15H30N3O3F9P2Ru: C, 28.39; H, 4.77;
N, 6.62. Found: C, 28.15; H, 4.62; N, 6.51. IR (cm-1): ν(CtO)
1964. 1H NMR (500 MHz, (CD3)2CO): 1.60 (9H, d, J PH ) 9.2
Hz, P(CH3)3), 3.1-3.6 (21H, m, Me3tacn). 13C{1H} NMR (125
MHz, (CD3)2CO): 204.8 (d, J ) 18.4 Hz, CO), 63.8, 62.9, 61.4,
61.1, 59.9, 58.7, 58.1, 53.1, 52.7 (Me3tacn), 16.4 (d, J ) 10.9
Hz, P(CH3)3). 31P{1H} NMR ((CD3)2CO): -3.6. FAB mass
spectrum: m/ z 490 [M+ - PF6].
[R u (Me3t a cn )(P Me3){η3-P h C3)CH (P h )}]P F 6
(5a ).
Meth od A. Complex 1b (0.15 g, 0.24 mmol), PhCtCH (0.06
g, 0.6 mmol), and KOH (0.02 g, 0.36 mmol) were refluxed in
methanol (15 cm3) for 18 h to give a clear red solution. After
cooling, the solution was concentrated to ca. 5 cm3 under
reduced pressure. Upon addition of NH4PF6, a red microcrys-
talline solid was formed. The solid was filtered, washed with
ice-cool ethanol and diethyl ether, and air-dried (yield ) 0.11
g, 67%).
Meth od B. Complex 2a (0.75 g, 1.0 mmol) was added
slowly to a hot methanolic KOH (0.06 g, 1.1 mmol) solution
(10 cm3) over 15 min to give a clear yellow solution which was
refluxed for a further 5 min. PhCtCH (0.11 g, 1.1 mmol) in
methanol (5 cm3) was then added dropwise to the yellow
solution to give a clear red solution which was refluxed for 5
h. The solution was then concentrated to ca. 5 cm3, and upon
addition of NH4PF6 a red microcrystalline solid formed. The
solid was filtered, washed with ice-cool ethanol and diethyl
ether, and then air-dried (yield ) 0.10 g, 62%). Anal. Calcd
for C28H41N3F6P2Ru: C, 48.27; H, 5.93; N, 6.03. Found: C,
48.23; H, 5.96; N, 6.05. 1H NMR (500 MHz, CD2Cl2) (the num-
bering scheme for the hydrogen and carbon resonances is given
in ref 21): 0.94 (9H, d, J PH ) 7.9 Hz, P(CH3)3), 1.63 (3H,
Resu lts a n d Discu ssion
(21) Numbering scheme for hydrogen and carbon atoms in 5a and
5b:
Zinc reduction of [Ru(Me3tacn)(OH2)2(O2CCF3)]2+ in
acetone in the presence of PMe3 and dmpe gives
[Ru(Me3tacn)(PMe3)2(O2CCF3)]PF6 (1a ) and [Ru(Me3-
tacn)(dmpe)(O2CCF3)]PF6 (1c), respectively. Similar
(22) PATTY & DIRDIF92: Beurskens, P. T.; Admiraal, G.; Beur-
sken, G.; Bosman, W. P.; Garcia-Grand, S.; Gould, R. O.; Smits, J . M.
M.; Smykalla C.(1992). The DIRDIF program system, Technical Report
of the Crystallography Laboratory, University of Nijmegen, The
Netherlands.

2822 Organometallics, Vol. 16, No. 13, 1997
Yang et al.
Ta ble 1. Cr ysta l Da ta for 3c a n d 5a
P r ep a r a t ion of Vin ylid en e Com p lexes [R u -
(Me3ta cn )(P Me3)(O2CCF 3){CdCH(R)}]P F 6 (R ) P h
(2a ); R ) p-tolyl (2b)) a n d σ-Acetylid e Com p lexes
[Ru (Me3ta cn )(L)(P Me3)(CtCR)]P F 6 (R ) P h , L )
P Me3 (3a ); R ) p-tolyl, L ) P Me3 (3b); R ) P h , L )
P (OMe)3 (3c)). [Ru(Me3tacn)(PMe3)2(O2CCF3)]PF6 (1a )
reacts with PhCtCH and p-tolylCtCH in refluxing 1,2-
dichloroethane to give the vinylidene complexes [Ru-
(Me3tacn)(PMe3)(O2CCF3){CdCH(R)}]PF6 (R ) Ph (2a )
and p-tolyl (2b)) respectively. No desired products are
obtained using alkylacetylenes such as 2-methyl-3-
butyn-2-ol, tert-butylacetylene, (trimethylsilyl)acetylene,
or 1-hexyne. Furthermore, no reaction was found
between 1c and PhCtCH after refluxing in 1,2-dichlo-
roethane or ethanol for 24 h. The chelating dmpe ligand
in 1c is expected to resist dissociation and prevent
subsequent reaction with the 1-alkyne. Hence dissocia-
tion of PMe3 to generate a coordination vacancy is
presumably the first step in the formation of 2a ,b.
Reaction between 1b and PhCtCH in 1,2-dichloro-
ethane gives impure [Ru(Me3tacn)(PMe3)(Cl){CdCH-
3c
5a
formula
Mr
C23H46N3O3F6P3Ru C28H41N3F6P2Ru
718.60
696.65
crystal dimensions/mm 0.30 × 0.20 × 0.20 0.25 × 0.35 × 0.50
space group
P1h
P21/c
a/Å
b/Å
c/Å
13.626(2)
13.772(3)
9.179(3)
109.06(2)
104.31(2)
91.18(2)
1567.8(7)
2
19.366(4)
9.330(2)
17.240(8)
R/deg
â/deg
100.73(3)
γ/deg
U/Å3
3060.5(2)
4
Z
Dc/g cm-3
1.522
1.512
µ/cm-1
7.18
6.63
F(000)
740
1428
T/K
2θmax
301
298
48.0
45.0
no. of data measured
no. of data used
no. of variables
3937
3435 (I > 3σ(I))
352
3984
2903 (I > 2σ(I))
361
a
R, Rw
0.053, 0.081
2.94
0.054, 0.055
1.13
GOF
(∆F)max
(∆/σ)max
-0.54, 1.15
0.01
-0.65, 0.91
0.05
1
(Ph)}]PF6 (identified by H NMR) in very low yield (ca.
5%) after reflux for 10 h. The observation that the rate
of formation for vinylidene complexes is faster for 1a
than for 1b warrants further comment. Since 1a and
1b are coordinatively saturated 18-electron species,
dissociation of PMe3 is likely to be the most endothermic
and hence the rate-determining step of vinylidene
formation. In this system, ground state destabilization
resulting in phosphine dissociation from [Ru(Me3tacn)-
(PMe3)2X]+ (X ) O2CCF3 (1a ), Cl (1b)) is negligible
because the steric requirement of X is small. In addi-
tion, the rate of PMe3 dissociation in CpRu(PMe3)2X (X
) halide, alkyl, hydride, amide, and hydroxy) have been
studied by Bercaw23 and Caulton.24 They suggested
that π-donation from X can stabilize the 16-electron
intermediate CpRu(PMe3)X, which results in a faster
dissociation rate. In both 1a and 1b, however, the
ligand X has π-electrons which can stabilize the 16-
electron species Ru(Me3tacn)(PMe3)X to a similar extent.
Hence this factor cannot account for the large difference
in the phosphine dissociation rate between 1a and 1b.
We attribute this to neighboring group participation by
the trifluoroacetate anion. This phenomenon has been
invoked previously in the oxidative addition and reduc-
tive elimination of square-planar platinum25 and irid-
ium26 complexes. Unlike in 1b, the lone pair of the
carboxylate group in 1a can interact with the metal
which lowers the activation energy for the dissociation
of PMe3 to form an 18-electron intermediate I1 (Scheme
1). The η2-trifluoroacetate anion in I1 isomerizes to an
η1-mode (I2) to provide a vacant site for the coordination
of RCtCH. The conversion between η1 and η2 bonding
modes for the carboxylate ligand is often observed in
the generation of coordination vacancy.27 It is likely
that the RCtCH is initially bound to the ruthenium
center in a side-on fashion (I3), and 1,2-hydrogen shift
subsequently occurs to give the vinylidene complex.
a
2
R ) ∑(|Fo| - |Fc|)/∑|Fo|. Rw ) (∑w(|Fo| - |Fc|)2/∑w|Fo| )1/2
.
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Ru (Me3ta cn )(P Me3)(P (OMe)3)-
(CtCP h )]P F 6 (3c)
Ru-P(1)
Ru-N(2)
2.225(2) Ru-P(2)
2.269(5) Ru-N(3)
2.337(2) Ru-N(1) 2.256(6)
2.226(5) Ru-C(1) 1.991(6)
C(1)-C(2) 1.235(8) C(2)-C(3) 1.426(8)
P(1)-Ru-P(2)
P(1)-Ru-N(2)
P(1)-Ru-C(1)
P(2)-Ru-N(2)
P(2)-Ru-C(1)
N(1)-Ru-N(3)
N(2)-Ru-N(3)
N(3)-Ru-C(1)
C(1)-C(2)-C(3)
85.6(1)
174.9(1)
93.1(2)
99.6(1)
83.6(2)
77.8(2)
79.1(2)
94.1(2)
176.6(6)
P(1)-Ru-N(1)
P(1)-Ru-N(3)
P(2)-Ru-N(1)
P(2)-Ru-N(3)
N(1)-Ru-N(2)
N(1)-Ru-C(1)
N(2)-Ru-C(1)
Ru-C(1)-C(2)
98.1(2)
96.0(1)
104.1(2)
177.3(1)
79.7(2)
166.8(2)
88.5(2)
173.0(5)
Ta ble 3. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for [Ru (Me3ta cn )(P Me3)-
{η3-P h C3dCH(P h )}]P F 6 (5a )
Ru-P(1)
Ru-N(3)
Ru-C(18)
2.307(3) Ru-N(1)
2.203(7) Ru-C(16)
2.181(6) Ru-N(2)
2.158(8) Ru-C(17)
2.231(5)
2.114(8)
2.058(8) C(15)-C(16) 1.47(1) C(16)-C(17) 1.26(1)
C(17)-C(18) 1.37(1) C(18)-C(19) 1.37(1)
P(1)-Ru-N(1)
P(1)-Ru-N(3)
P(1)-Ru-C(17)
N(1)-Ru-N(2)
N(1)-Ru-C(16)
N(1)-Ru-C(18)
N(2)-Ru-C(16)
N(2)-Ru-C(18)
N(3)-Ru-C(17)
C(16)-Ru-C(17)
C(17)-Ru-C(18)
Ru-C(16)-C(17)
Ru-C(17)-C(16)
98.7(2) P(1)-Ru-N(2)
177.9(2)
88.4(2)
88.2(2)
79.5(3)
139.1(3)
83.2(3)
90.2(3)
105.8(3)
173.1(3)
72.5(3)
152.7(6)
98.5(2) P(1)-Ru-C(16)
87.7(2) P(1)-Ru-C(18)
82.8(3) N(1)-Ru-N(3)
170.5(3) N(1)-Ru-C(17)
101.2(3) N(2)-Ru-N(3)
89.9(3) N(2)-Ru-C(17)
90.1(3) N(3)-Ru-C(16)
139.8(3) N(3)-Ru-C(18)
34.3(3) C(16)-Ru-C(18)
38.3(3) Ru-C(16)-C(15)
70.9(5) C(15)-C(16)-C(17) 136.1(8)
74.8(5) Ru-C(17)-C(18)
68.7(5)
73.1(5)
C(16)-C(17)-C(18) 143.4(8) Ru-C(18)-C(17)
Ru-C(18)-C(19)
149.7(6) C(17)-C(18)-C(19) 137.2(8)
C(18)-C(19)-C(20) 126.3(7)
(23) Bryndza, H. E.; Domaille, P. J .; Paciello, R. A.; Bercaw, J . E.
Organometallics 1989, 8, 379.
(24) Caulton, K. G. New J . Chem. 1994, 18, 25.
(25) Constable, A. G.; Langrick, C. R.; Shabanzadeh, B.; Shaw, B.
L. Inorg. Chim. Acta 1982, 65, L151.
(26) Miller, E. M.; Shaw, B. L. J . Chem. Soc., Chem. Commun. 1974,
480.
(27) (a) Braun, T.; Gevert, O.; Werner, H. J . Am. Chem. Soc. 1995,
117, 7291. (b) Scher, M.; Wolf, J .; Werner, H. J . Chem. Soc., Chem.
Commun. 1991, 1341.
ruthenium complexes of Me3tacn with π-acid ligands
have been reported.18 In addition, Ru(Me3tacn)Cl3
reacts with PMe3 in ethanol in the presence of zinc to
yield [Ru(Me3tacn)(PMe3)2Cl]PF6 (1b) in moderate yield.
Attempts to prepare the bulkier PPh3 analogues [Ru(Me3-
tacn)(PPh3)2X]PF6 (X ) Cl or O2CCF3) were unsuccess-
ful.

Ruthenium Vinylidene and σ-Acetylide Complexes
Organometallics, Vol. 16, No. 13, 1997 2823
Sch em e 1
reaction with primary and secondary amines. Hence
upon addition of tert-butylamine to an acetone-d6 solu-
1
tion of 2a , the vinylidene proton signal in the H NMR
spectrum vanishes and the σ-acetylide complex is
formed (see below). This is in contrast to the report by
Bianchini that primary and secondary amines react
with ruthenium vinylidene derivatives to give amino-
carbene and isocyanide complexes.14a We propose that
complexes 2a ,b are resistant to nucleophilic addition as
a result of electronic rather than steric factors: the
auxiliary ligands in the present system do not appear
to impart steric hindrance, while the high π-basicity of
the [Ru(Me3tacn)] fragment is expected to lower the
electrophilicity of the R-carbon atom.
Reaction of 2a and 2b with methanolic KOH in the
presence of phosphine L (L ) PMe3 or P(OMe)3) affords
the σ-acetylide complexes [Ru(Me3tacn)(PMe3)L(CtCR)]+
(R ) Ph, L ) PMe3 (3a ), R ) p-tolyl, L ) PMe3 (3b), R
) Ph, L ) P(OMe)3 (3c)). It is noteworthy that the
expected formation of the σ-acetylide species via direct
substitution of 1b with the appropriate Grignard re-
agent does not give the desired products. The use of
amines, e.g. triethylamine, tert-butylamine, as base
results in lower yields. The vinylidene derivative 2a is
first deprotonated by KOH to give the σ-acetylide
intermediate; substitution of the CF3CO2 ligand by
PMe3 then proceeds to give 3a . Complexes 3b and 3c
are presumably formed via similar reaction pathways.
In the 13C{1H} NMR spectra for complexes 3a -c, a
singlet is observed at 108-110 ppm for the â-acetylide
carbon (hence no phosphorus coupling). 3a and 3b both
show five resonances in the range 55-63 ppm which
correspond to the Me3tacn ligand and suggest Cs sym-
metry. In complex 3c, nine carbon resonances are
assigned to Me3tacn, and this implies the presence of
Ci symmetry. Large coupling in the 31P{1H} NMR
spectrum (2J PP ) 70.5 Hz) between PMe3 and P(OMe)3
is evident. A triplet at ca. 131 ppm in the 13C{1H} NMR
spectrum of 3a is assigned to the R-carbon, but an
analogous signal for 3b and 3c is obscured by phenyl
resonances. The IR spectra for 3a -c each show an
intense absorption band at ca. 2060 cm-1 for the CtC
moiety.
Introduction of dioxygen into a 1,2-dichloroethane
solution of 2a affords [Ru(Me3tacn)(CO)(PMe3)-
(O2CCF3)]+ (4) and benzaldehyde. Oxidative cleavage
of vinylidene ligands have been previously reported.31
We found that the incorporation of an electron-with-
drawing group (e.g. NO2, Cl) into the para position of
the phenyl ring in 2a leads to longer reaction times.32
The stability of the vinylidene complexes toward oxida-
tion therefore increases as the electron density at the
CdC bond decreases. The FAB mass spectrum of 4
reveals a cluster at m/ z 490 which corresponds to the
parent cationic fragment [Ru(Me3tacn)(PMe3)(O2CCF3)-
The vinylidene complexes 2a and 2b are air-stable
solids. Their IR spectra each contain bands at ca. 1710
and 1620 cm-1 which are typical for the stretching
frequencies of the CdO and CdC groups in η1-O2CCF3
and vinylidene ligands, respectively. The 31P{1H} NMR
spectra show a single resonance at -3.0 and -3.8 ppm
for the coordinated PMe3 in 2a and 2b, respectively.
Their 13C{1H} NMR spectra each reveal a low-field
doublet at ca. 363 ppm (2J PC ≈ 23 Hz) for the metal-
bonded vinylidene carbon while the resonance for the
â-carbon is at ca. 110 ppm. The spectroscopic data
confirm that 2a is a vinylidene complex rather than a
metallacyclic vinyl ester compound because the latter
would display a lower 13C resonance and ν(CdO) band
1
for CR and the CF3CO2 group, respectively.28 In the H
NMR spectra, the chemical shifts of the vinylidene
protons in 2a and 2b (5.47 and 5.13 ppm, respectively)
are similar to the related complexes [Ru(η-C5H5)(PPh3)2
{CdCH(Ph)}]PF6 (5.43 ppm),11a [Ru(η-C6Me6)(PMe3)-
(Cl){CdCH(Ph)}]PF6 (5.66 ppm),12a and [Ru(P(OMe)3)4-
(CtCPh){CdCH(Ph)}]PF6 (5.98 ppm).29
Nucleophilic attack at the R-carbon of vinylidene
complexes to give heteroatom-stabilized carbene species
is well established and can be affected by the steric and
electronic properties of the spectator ligands.30 Complex
2a and 2b are stable in refluxing methanol, while only
deprotonation of the vinylidene ligand is observed upon
(CO)]+. A low-field doublet at 204.8 ppm (2J PC
)
28.6Hz) in the 13C NMR spectrum and a strong absorp-
tion at 1964 cm-1 in the IR spectrum are characteristic
of a terminal carbonyl ligand.
Syn t h esis of η3-Bu t en yn yl Com p lexes [R u -
(Me3ta cn )(P Me3){η3-RC3dCH(R)}]P F 6 (R ) P h (5a ),
(28) Daniel, T.; Mahr, N.; Braun, T.; Werner, H. Organometallics
1993, 12, 1475.
(29) Albertin, G.; Antoniutti, S.; Bordignon, E.; Cazzaro, F.; Ianelli,
S.; Pelizzi, G. Organometallics 1995, 14, 4114.
(31) (a) Mezzetti, A.; Consiglio, G.; Morandini, F. J . Organomet.
Chem. 1992, 430, C15. (b) Oro, L. A.; Ciriano, M. A.; Foces-Foces, C.;
Cano, F. M. J . Organomet. Chem. 1985, 289, 117. (c) Bruce, M. I.;
Swincer, A. G.; Wallis, R. C. J . Organomet. Chem. 1979, 171, C5.
(32) Yang S. M.; Che, C. M. Unpublished results.
(30) Bruce, M. I.; Swincer, A. G. Aust. J . Chem. 1980, 33, 1471.

2824 Organometallics, Vol. 16, No. 13, 1997
Yang et al.
Sch em e 2. P r op osed Mech a n ism for th e
p-tolyl (5b)). Reaction of excess PhCtCH and KOH
with [Ru(Me3tacn)(PMe3)2Cl]PF6 (1b) in refluxing metha-
nol gives a orange-red solution from which red crystals
of [Ru(Me3tacn)(PMe3){η3-PhC3dCH(Ph)}]PF6 (5a ) are
obtained (method A). Similarly, [Ru(Me3tacn)(PMe3)-
{η3-(p-tolyl)C3dCH(p-tolyl)}]PF6 (5b ) is formed using
p-tolylCtCH. Treatment of the vinylidene complexes
2a and 2b with KOH followed by RCtCH in refluxing
methanol also gives 5a and 5b, respectively (method B).
Formation of η3-butenynyl complexes from well-defined
ruthenium2b and tungsten33 precursors have been re-
ported.
F or m a tion of 5c/5c′
Using method A, we attempted to isolate the inter-
mediate(s) of the reaction by adding diethyl ether to the
mixture after reflux for 30 min to precipitate all ionic
species present. A red solid and colorless solution were
afforded, and the 1H NMR spectrum of the solid
consisted of three species: starting complex 1b (PMe3
protons at 1.49 ppm), a small amount of 5a (character-
istic vinyl proton at 6.94 ppm), and small amounts of
an unknown species with a doublet at ca. 5.5 ppm. Due
to the similarities between these resonances and that
of 2a , we suggest that this species is a vinylidene
intermediate in the formation of 5a . This assertion is
further supported by the successful synthesis of 5a from
the vinylidene complex 2a via method B.
The 1H and 13C{1H} signals of the 1,4′-di(p-tolyl)-
butenynyl ligand in complex 5b have been assigned by
DEPT-135, HMBC, and HSQC 13C-1H COSY NMR
experiments. In the 13C{1H} NMR spectrum, three
small doublets appearing at 55.8 ppm (2J PC ) 1.5 Hz),
123.8 (2J PC ) 5.4 Hz), and 157.5 ppm (2J PC ) 7.6 Hz)
correlate to the ruthenium-bonded C2, C1, and C3
atoms respectively. The 1H, 13C{1H}, and 13C-1H COSY
NMR spectra of 5a are similar to those of 5b, except
the 1H resonances in 5b at 2.33 and 2.39 ppm are
intensity at 2.39 and 2.45 ppm are assigned to the
methyl hydrogens of the p-tolyl groups.
In order to eliminate the possibility that the isolated
red solid is an equimolar mixture of 5a and 5b, we have
1
also recorded the H and 31P{1H} NMR spectra and the
1
FAB mass spectrum of such a mixture. In the H NMR
1
attributed to the p-tolyl methyl groups. The H NMR
spectrum, two signals at 6.94 and 6.88 ppm are visible
for the vinylic protons of 5a and 5b, respectively, while
the analogous resonances for 5c/5c′ are absent. The
methyl hydrogens for the p-tolyl substituents appear at
2.33 and 2.39 ppm. Moreover, the 31P{1H} NMR
spectrum shows two signals at 4.8 and 5.2 ppm which
correspond to the PMe3 ligand in 5a and 5b, respec-
tively; again the corresponding peaks for 5c/5c′ are not
observed. The FAB mass spectrum does not show a
cluster at m/ z 566. Hence there is no signals corre-
sponding to the red product from the reaction of 2a with
p-tolylCtCH, which is a 1:1 mixture of [Ru(Me3tacn)-
(PMe3){η3-PhC3dCH(p-tolyl)}]PF6 (5c) and [Ru(Me3-
tacn)(PMe3){η3-(p-tolyl)C3dCH(Ph)}]PF6 (5c′). Finally,
the analogous reaction between complex 2b with phen-
ylacetylene also gives 5c/5c′ as a red solid with identical
spectroscopic properties. The molecular structure of 5c/
5c′ (see the Supporting Information) shows coordination
of the η3-butenynyl fragment to the metal center as in
the structure of 5a .
spectra of 5a and 5b each contain a singlet at ca. 6.9
ppm which is assigned to the vinylic proton of the 1,4′-
disubstituted η3-butenynyl ligand. One Me3tacn methyl
group appears at a higher field in both the 1H and
13C{1H} NMR spectra (ca. 1.6 and 48 ppm, respectively)
than other signals for the ligand (2.4-3.6 ppm for 1H
and 58-63 ppm for 13C). It is apparent from the X-ray
structure of 5a (vide infra) that this methyl substituent
is located above one of the phenyl rings of the η3-
butenynyl moiety and is therefore shielded by the
diamagnetic ring current.
[R u (Me3t a cn )(P Me3){η3-P h C3dCH (p -t olyl)}]P F 6
(5c) a n d [Ru (Me3ta cn )(P Me3){η3-(p-tolyl)C3dCH-
(P h )}]P F 6 (5c′): Syn th esis a n d Mech a n ism . Reac-
tion of 2a with p-tolylCtCH in methanolic KOH gives
a red solid. The FAB mass spectrum shows a cluster
around m/ z 566 which can be assigned to the isomeric
fragments [Ru(Me3tacn)(PMe3){η3-PhC3dCH(p-tolyl)}]+
(5c) or [Ru(Me3tacn)(PMe3){η3-(p-tolyl)C3dCH(Ph)}]+
(5c′). The 31P{1H} NMR spectrum shows a slightly
broad signal at 5.0 ppm, while the 1H and 13C{1H} NMR
spectra are uninformative due to overlapping signals.
Scheme 2 depicts our proposed mechanism for the
formation of the η3-butenynylruthenium(II) complexes
5c and 5c′. The stepwise mechanism is related to others
previously reported.34 However, the location of the
p-tolyl substituent in the final products provide inter-
esting mechanistic information.
1
Nevertheless, the H NMR spectrum shows two signals
of equal intensity at 6.91 and 6.93 ppm which are
attributed to the vinylic protons of the η3-butenynyl
moieties in 5c and 5c′. In addition, two peaks of equal
We have demonstrated that 1 molar equiv of KOH
serves to deprotonate the vinylidene ligand in the
preparation of 3a -c. We propose that the reaction of
(33) McMullen, A. K.; Selegue, J . P.; Wang, J . G. Organometallics
1991, 10, 3421.

Ruthenium Vinylidene and σ-Acetylide Complexes
Organometallics, Vol. 16, No. 13, 1997 2825
Sch em e 3
2a with p-tolylacetylene in the presence of KOH yields
the (η2-p-tolylCtCH)(σ-CtCPh) intermediate IA. Re-
arrangement of p-tolylCtCH results in formation of the
(vinylidene)(σ-acetylide) intermediate IB, and subse-
quent 1,2-migratory insertion of the acetylide gives the
observed complex 5c. The formation of the 5c′ isomer
gives greater insight into the reaction mechanism.35
Complex 5c′ is derived from the (σ-p-tolylacetylide)-
(phenylvinylidene) intermediate IB′ which is generated
by the isomerization of IB through proton transfer.
From a thermodynamic viewpoint, the strong basicity
at the â-carbon of the acetylide moiety and the high
acidity of the vinylidene proton will favor the proton
migration, and this is further facilitated by the electron-
donating nature of the [Ru(Me3tacn)] fragment. Such
proton transfer processes have not been observed by
Bianchini.2b We believe that the isomerization is ki-
netically unfavored in aprotic solvents, while in our
system the proton transfer/isomerization can be assisted
by the methanol solvent (Scheme 3). Moreover, we
assume that the C-C coupling is slower than the rate
of proton transfer partly because of the weak trans effect
of the Me3tacn ligand. Hence, the isomeric intermedi-
ates IB and IB′ are generated in equilibrium, and this
results in the formation of 5c and 5c′ in equal propor-
tions.
F igu r e 1. Perspective view of the cation in [Ru(Me3tacn)-
(PMe3)(P(OMe)3)(CtCPh)]PF6 (3c).
X-r a y Cr ysta l Str u ctu r es of 3c a n d 5a . Figures 1
and 2 show perspective views of the cations in 3c and
5a respectively. Selected bond distances and angles are
presented in Tables 2 and 3, respectively.
The coordination geometry around the ruthenium
center in 3c is a distorted octahedron with the metal
atom surrounded by two phosphines, three nitrogen
atoms of Me3tacn, and a σ-acetylide ligand. The three
Ru-N distances are comparable. The most evident
distortion from idealized geometry is the bending of the
acetylide moiety toward Me3tacn and PMe3 (N(2)-Ru-
C(1) 88.5(2)°, P(2)-Ru-C(1) 83.6(2)°). The Ru-P dis-
tances are shorter for the more electron-accepting
P(OMe)3 (Ru-P(1) 2.225(2) Å) than for PMe3 (Ru-P(2)
2.337(2) Å). Since the cone angles of P(OMe3)3 and
F igu r e 2. Perspective view of the cation in [Ru(Me3tacn)-
(PMe3){η3-PhC3dCH(Ph)}]PF6 (5a ).
PMe3 are similar (107° and 118°, respectively),36 the
strong π-basicity of the [Ru(Me3tacn)] fragment appar-
ently results in a stronger bond with P(OMe3)3. The
ethynyl moiety is almost linear (Ru-C(1)-C(2) 173.0(5)°)
and the Ru-C separation of 1.991(6) Å is within the
range expected for ruthenium(II) σ-acetylide com-
plexes.37 The high-energy IR stretch (2065 cm-1) of the
CtC bond is consistent with the C(1)-C(2) bond length
of 1.235(8) Å, which is comparable to that in disubsti-
tuted organic alkynes (ca. 1.20 Å)38 and organometallic
alkynyl complexes (1.14-1.24 Å).39
The molecular structure of 5a corresponds to that
elucidated spectroscopically for the p-tolyl derivative 5b.
The ruthenium center is in a distorted octahedral
environment assuming the η3-butenynyl ligand is oc-
cupying two sites. The salient feature of 5a is the
(34) (a) Albertin, G.; Antoniutti, S.; Bordignon, E. J . Chem. Soc.,
Dalton Trans. 1995, 719. (b) Werner, H. J . Organomet. Chem. 1994,
475, 45. (c) Santos, A.; Lez, J .; Matas, L.; Ros, J .; Gal, A.; Echavarren,
A. M. Organometallics 1993, 12, 4215. (d) Scher, M.; Mahr, N.; Wolf,
J .; Werner, H. Angew. Chem., Int. Ed. Engl. 1993, 32, 1315. (e)
Bianchini, C.; Bohanna, C.; Esteruelas, M. A.; Frediani, P.; Meli. A.;
Oro, L. A.; Peruzzini, M. Organometallics 1992, 11, 3837. (f) Field, L.;
George, A. V.; Purches, G. R.; Slip, I. H. M. Organometallics 1992, 11,
3019. (g) Wakatsuki, Y.; Yamazaki, H.; Kunegawa, N.; Satoh, J . Y.;
Satoh, T. J . Am. Chem. Soc. 1991, 113, 9604. (h) Albertin, G.;
Amendola, P.; Antoniutti, S.; Ianelli, S.; Pelizzi, G.; Bordignon, E.
Organometallic 1991, 10, 2876. (i) J ia, G.; Meek, D. W. Organometallics
1991, 10, 1411.
(35) The possibility that 5c/5c′ are interconvertible by acid- or base-
catalyzed isomerization was suggested by one reviewer. However, this
is ruled out since no changes are observed by 1H NMR spectroscopy
for the treatment of 5b with CF3CO2D or CD3ONa in CD3OD.
(36) Tolman, C. A. Chem. Rev. 1977, 77, 313.
(37) Whittall, I. R.; Humphrey, M. G.; Hockless, D. C. R.; Skelton,
B. W.; White, A. H. Organometallics 1995, 14, 3970 and reference
therein.

2826 Organometallics, Vol. 16, No. 13, 1997
Ta ble 4. Com p a r ison of Str u ctu r a l Da ta for th e Com p lexes Ru Ln {η3-P h C3)CH(P h )}
Yang et al.
RuLn
a (Å)
b (Å)
c (Å)
d (Å)
e (Å)
f (Å)
R (deg)
â (deg)
γ (deg)
ref
[Ru(Me3tacn)(PMe3)]+ (5a )
[Ru(CO)2(PPh3)2]+
1.366
1.319
1.335
1.343
1.339
1.34
1.368
1.371
1.416
1.396
1.379
1.41
1.260
1.244
1.220
1.248
1.249
1.23
2.058
2.170
2.040
2.084
2.200
2.06
2.114
2.233
2.229
2.169
2.191
2.19
2.158
2.320
2.558
2.319
2.258
2.39
137.2
138.1
129.2
130.4
133.1
130
143.4
147.4
154.3
148.2
148.7
150
136.1
148.7
156.7
147.0
144.6
154
this work
41a
41b
41b
41c
[RuCl(Cyttp)] (syn-mer)a
[RuCl(Cyttp)] (anti-mer)a
[Ru(CtCPh)(Cyttp)]a
[Ru(PNP)(CtCPh)] (anti-mer)b
[Ru(PMe2Ph)4]+
2b
41d
1.341
1.401
1.229
2.119
2.226
2.510
131.1
155.3
155.8
a
b
Cyttp ) PhP{(CH2)3P(C6H11)2}2. PNP ) CH3(CH2)3P(CH2CH2PPh2)2.
[RuC3] unit of the η3-butenynyl group. Structural
parameters associated with this fragment for several
related ruthenium complexes are collected in Table 4.
The small bend-back angle γ for 5a (136.1(8)°) falls in
the range of metal-diphenylacetylene interactions (135-
140°)40 and suggests strong interaction between C(16)/
C(17) and Ru. This is supported by the short corre-
sponding bond distances e and f, while elongation of the
C(16)-C(17) contact (distance c) to 1.260(1) Å is also
observed. The greater interaction between the η3-
butenynyl unit and the ruthenium center in 5a com-
pared to other examples in Table 4 is believed to be a
consequence of the strong π-basicity of the [Ru(Me3-
tacn)] moiety.
η1/η2 isomerization of the CF3CO2 ligand in 1a . The
vinylidene complexes [Ru(Me3tacn)(PMe3)(O2CCF3)-
{CdCH(R)}]PF6 (R ) Ph (2a ) and p-tolyl (2b)) are
prepared by the reaction of 1a with the appropriate
1-alkyne. Due to the high π-basicity of the [Ru(Me3-
tacn)] moiety which lowers the electrophilicity of the
vinylidene R-carbon, no nucleophilic addition across the
CdC bond is observed. Alkyne coupling reactions to
give η3-butenynyl complexes 5a , 5b, and 5c/5c′ are
studied. It is significant that, partly due to the weak
trans effect of the saturated triamine, coupling of the
σ-acetylide and vinylidene groups is slower than proton
migration between these two ligands for IB and IB′
(Scheme 2) in methanol. An equilibrium between these
isomeric intermediates is thus established and yields
an unprecedented mixture of 5c and 5c′.
Con clu sion
The rate of PMe3 dissociation in [Ru(Me3tacn)-
(PMe3)2X]+ (X ) O2CCF3 (1a ), Cl (1b)) is enhanced by
Ack n ow led gm en t. We thank The University of
Hong Kong and the Hong Kong Research Grants
Council for support and S.-M.Y. is grateful for a
Croucher Scholarship administrated by the Croucher
Foundation of Hong Kong.
(38) (a) Ittel, S. D.; Ibers, J . A. Adv. Organomet. Chem. 1976, 14,
33. (b) March, J . Advanced Organic Chemistry, 4th ed.; Wiley: New
York, 1992.
(39) (a) Montoya, J .; Santos, A.; Lopez, J .; Echavarren, A. M.; Ros,
J .; Romero, A. J . J . Organomet. Chem. 1992, 426, 383. (b) Bruce, M.
I.; Humphrey, M. G.; Snow, M. R.; Tiekink, E. R. T. J . Organomet.
Chem. 1986, 314, 213. (c) Consiglio, G.; Morandini, F.; Sironi, A. J .
Organomet. Chem. 1986, 306, C45.
(40) (a) Decian, A.; Colin, A.; Schappacher, M.; Richard, L.; Weiss,
R. J . Am. Chem. Soc. 1981, 103, 1850. (b) Sunkel, K.; Nagel, U.; Beck,
W. J . Organomet. Chem. 1981, 222, 252.
(41) (a) Liles, D. C.; Verhoeven, P. F. M. J . Organomet. Chem. 1996,
522, 33. (b) Alcock, N. W.; Hill, A. F.; Melling, R. P.; Thompsett, A. R.
Organometallics 1993, 12, 641. (c) J ia, G.; Gallucci, J . C.; Rheingold,
A. L.; Haggerty, B. S.; Meek, D. W. Organometallics 1991, 10, 3459.
(d) J ia, G.; Rheingold, A. L.; Meek, D. W. Organometallics 1989, 8,
1378.
Su p p or tin g In for m a tion Ava ila ble: Tables of final
positional parameters, anisotropic displacement parameters
and bond lengths and angles for 3c, 5a , and 5c/5c′ (27 pages).
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