Synthesis and reactivity of RuCp*(κ2(P,N)-Ph2PCH2CH 2NMe2)Cl. Chelate-assisted methyl C-H activation and formation of the novel complex [RuCp*(κ3(P,N,C)-Ph2PCH2CH <sub

Article abstract of DOI:10.1021/om9610408

RuCp*(κ²(P,N)-Ph₂PCH₂CH ₂NMe₂)Cl (1) is afforded in 87% yield by the reaction of RuCp*-(η⁴-isoprene)Cl with 1 equiv of Ph₂PCH₂CH₂NMe₂ in CH₂

Full text of DOI:10.1021/om9610408

1956
Organometallics 1997, 16, 1956-1961
Syn th esis a n d Rea ctivity of
Ru Cp *(K2(P ,N)-P h 2P CH2CH2NMe2)Cl. Ch ela te-Assisted
Meth yl C-H Activa tion a n d F or m a tion of th e Novel
Com p lex [Ru Cp *(K3(P ,N,C)-
P h 2P CH2CH2N(CH2)Me)Cl]BP h 4
Klaus Mauthner,† Christian Slugovc,† Kurt Mereiter,‡ Roland Schmid,† and
Karl Kirchner*,†
Institute of Inorganic Chemistry and Institute of Mineralogy, Crystallography, and Structural
Chemistry, Technical University of Vienna, Getreidemarkt 9, A-1060 Vienna, Austria
Received December 10, 1996X
RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)Cl (1) is afforded in 87% yield by the reaction of RuCp*-
(η4-isoprene)Cl with 1 equiv of Ph2PCH2CH2NMe2 in CH2Cl2 as the solvent. The hemilabile
nature of the Ph2PCH2CH2NMe2 ligand in 1 is revealed by the reaction with carbon monoxide,
whereupon the neutral complex RuCp*(κ1(P)-Ph2PCH2CH2NMe2)(Cl)(CO) (2) is obtained
bearing the Ph2PCH2CH2NMe2 ligand in κ1(P)-coordinated fashion. Chloride abstraction
from 1 with TlCF3SO3 led to RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)(η1-OSO2CF3) (3), where
CF3SO3- is directly bound to the metal center. Both 1 and 3 are convenient precursors for
the synthesis of the cationic vinylidene complex [RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)-
(dCdCHPh)]+ (4). When chloride abstraction from 1 was performed with NaBPh4 in CH2-
Cl2 instead of TlCF3SO3 in tetrahydrofuran as the solvent, the novel cationic Ru(IV) complex
[RuCp*(κ3(P,N,C)-Ph2PCH2CH2N(CH2)Me)Cl]+ (5) was formed. This reaction likely proceeds
via the cationic 16e- complex [RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)]+, which then readily
undergoes methyl â-hydrogen elimination to give the cyclometalated cationic hydrido complex
[RuCp*(κ3(P,N,C)-Ph2PCH2CH2N(CH2)Me)H]+. This latter complex is trapped in CH2Cl2 or
CD2Cl2 as the chloro complex 5. Preliminary results on the catalytic activity of 1 are also
presented. Thus, 1 is shown to catalyze the dimerization and cyclotrimerization of some
terminal alkynes HCtCR. Whereas with R ) Ph, SiMe3, and n-Bu, isomeric mixtures of
head-to-head and head-to-tail coupling products are obtained, in the case of R ) COOEt,
cyclotrimerization takes place exclusively. X-ray structures of complexes 1, 3, 4, and 5 are
presented.
In tr od u ction
acetylene-to-vinylidene tautomerizations1c,e,f or the con-
version of a metal-(η2-CH2dCH2) to a metal-(H)(η1-
CHdCH2) unit.2 Furthermore, complexes of these types
appear to be effective catalyst precursors for olefin
oligomerizations and polymerizations, carbonylations of
methanol and methyl acetate, and hydrogenations.1d
Therefore, we have been investigating some ruthe-
nium complexes with hemilabile ligands in order to
examine their efficiency in stoichiometrically and cata-
lytically operating processes. Here we report on the
synthesis and reactivity of the ruthenium half-sandwich
complex RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)Cl (1). The
hemilabile nature of the Ph2PCH2CH2NMe2 ligand in
1 is demonstrated, and a preliminary account of the
catalytic activity of 1 is given. In addition, we describe
a novel chelate-assisted oxidative addition of a methyl
C-H bond. X-ray structures of some of the new
complexes are presented.
Late transition metal complexes containing hemila-
bile phosphino ethers, esters, and amines have been the
subject of recent investigations.1 Under appropriate
conditions, these soft/hard assemblies are able to coor-
dinate reversibly to a metal center, thus providing or
protecting temporarily a vacant coordination site. Along
these lines, complexes with P-O and P-N ligands have
been found to facilitate several stoichiometric and
catalytic transformations of organic molecules such as
* To whom correspondence should be addressed. E-mail: kkirch@
fbch.tuwien.ac.at.
† Institute of Inorganic Chemistry.
‡ Institute of Mineralogy, Crystallography, and Structural Chem-
istry.
X Abstract published in Advance ACS Abstracts, April 1, 1997.
(1) (a) Lindner, E.; Haustein, M.; Mayer, H. A.; Gierling, K.; Fawzi,
R.; Steinmann, M. Organometallics 1995, 14, 2246. (b) Lindner, E.;
Haustein, M.; Fawzi, R.; Steinmann, M.; Wegner, P. Organometallics
1994, 13, 5021. (c) Lindner, E.; Gepra¨gs, M.; Gierling, K.; Fawzi, R.;
Steinmann, M. Inorg. Chem. 1995, 34, 6106. (d) Bader, A.; Lindner,
E. Coord. Chem. Rev. 1991, 108, 27 and references therein. (e) Werner,
H.; Stark, A.; Schulz, M.; Wolf, J . Organometallics 1992, 11, 1126. (f)
Martin, M.; Gevert, O.; Werner, H. J . Chem. Soc., Dalton Trans. 1996,
2275. (g) Braunstein, P.; Chauvin, Y.; Na¨hring, J .; Dusausoy, Y.;
Bayeul, D.; Tiripicchio, A.; Ugozzoli, F. J . Chem. Soc., Dalton Trans.
1995, 851. (h) Braunstein, P.; Matt, D.; Nobel, D.; Bouaoud, S.-E.;
Carluer, B.; Grandjean, D.; Lemoine, P. J . Chem. Soc., Dalton Trans.
1986, 415.
Exp er im en ta l Section
Gen er a l In for m a tion . All manipulations were performed
under an inert atmosphere of purified argon by using Schlenk
techniques. All chemicals were standard reagent grade and
(2) Werner, H.; Schulz, M.; Windmu¨ller, B. Organometallics 1995,
14, 3659.
S0276-7333(96)01040-0 CCC: $14.00 © 1997 American Chemical Society

Study of RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)Cl
Organometallics, Vol. 16, No. 9, 1997 1957
used without further purification. The solvents were purified
according to standard procedures. The deuterated solvents
were purchased from Aldrich and dried over 4 Å molecular
sieves. RuCp*(η4-isoprene)Cl and Ph2PCH2CH2NMe2(pn) were
prepared according to the literature.3,4 1H, 13C{1H}, and 31P-
{1H} NMR spectra were recorded on a Bruker AC-250 spec-
trometer operating at 250.13, 62.86, and 101.26 MHz, respec-
tively, and were referenced to SiMe4 and H3PO4 (85%). FT-
IR spectra were recorded on a Mattson RS 2 spectrometer.
Microanalyses were done by Microanalytical Laboratories,
University of Vienna.
Syn th esis. Ru Cp *(K2(P ,N)-P h 2P CH2CH2NMe2)Cl (1).
To a solution of RuCp*(η4-isoprene)Cl (2.00 g, 5.88 mmol) in
CH2Cl2 (10 mL) was added Ph2PCH2CH2NMe2 (1.51 g, 5.88
mmol) dissolved in 35 mL of CH2Cl2 slowly within a period of
4 h. After being stirred for an additional hour, the volume of
the solution was reduced to about 5 mL, and petroleum ether
(30 mL) was added. A precipitate was formed which was
collected on a glass frit, washed with petroleum ether, and
dried under vacuum. Yield: 2.71 g (87%). Anal. Calcd for
under vacuum. Yield: 0.22 g (95%) as red crystals. Anal.
Calcd for C35H41F3NO3PSRu: C, 56.44; H, 5.55. Found: C,
56.55; H, 5.56. 1H NMR (δ, CD2Cl2, 20 °C): 7.70-6.80 (m,
15H), 4.26 (d, 1H, J HP ) 3.0 Hz), 3.50-2.70 (m, 4H), 2.83 (s,
3H), 2.77 (s, 3H), 1.63 (d, 15H, J HP ) 1.5 Hz). 13C{1H} NMR
(δ, CD2Cl2, 20 °C): 347.8 (d, J CP ) 13.8 Hz, dCdCHPh),
134.0-125.5 (Ph), 117.4 (dCdCHPh), 101.6 (d, J CP ) 1.3 Hz,
C5Me5), 66.0 (d, J CP ) 3.1 Hz, NCH2), 62.4 (NMe), 55.6 (NMe),
30.4 (d, J CP ) 26.2 Hz, PCH2), 10.3 (C5Me5). 31P{1H} NMR (δ,
CDCl3, 20 °C): 65.4. Single crystals were obtained by slow
diffusion of diethyl ether into a solution of 4 in CH2Cl2.
[Ru Cp *(K3(P ,N,C)-P h 2P CH2CH2N(CH2)Me)Cl]BP h 4 (5).
A solution of 1 (0.25 g, 0.472 mmol) in CH2Cl2 (5 mL) was
treated with NaBPh4 (0.178 g, 0.520 mmol), and the mixture
was stirred for 24 h. Insoluble materials were removed by
filtration. To the clear solution was added 25 mL of n-hexane,
whereupon a yellow precipitate was formed, which was col-
lected on a glass frit, washed with n-hexane, and dried under
vacuum. Yield: 0.32 g (80%). Anal. Calcd for
C50H54-
BClNPRu: C, 70.88; H, 6.42; N, 1.65; Cl, 4.18. Found: C,
71.09; H, 6.44; N, 1.70; Cl, 4.21. 1H NMR (δ, CDCl3, 20 °C):
7.6-6.80 (m, 30H), 3.21 (d, 1H, J HP ) 9.5 Hz), 2.93 (s, 1H),
2.57 (s, 3H), 2.60-1.80 (m, 4H), 1.47 (d, 15H, J HP ) 1.5 Hz).
13C{1H} NMR (δ, CD2Cl2, 20 °C): 163.8 (q, J BC ) 49.3 Hz),
135.6, 133.1-128.3, 125.8, 121.9, 102.8 (d, J CP ) 2.3 Hz, C5-
Me5), 54.9 (NCH2), 52.3 (d, J CP ) 5.5 Hz, NCH2Ru), 50.0 (NMe),
22.0 (d, J CP ) 24.1 Hz, PCH2), 9.8 (C5Me5). 31P{1H} NMR (δ,
CDCl3, 20 °C): 53.6. Single crystals were obtained by slow
diffusion of diethyl ether into a solution of 5 in CH2Cl2.
Rea ction of 3 w ith CD2Cl2. A 5 mm NMR tube was
charged with a solution of complex 3 (30 mg) in CD2Cl2 (0.5
mL). 1H, 13C{1H}, and 31P{1H} NMR spectra were recorded,
C
26H35ClNPRu: C, 59.02; H, 6.68. Found: C, 59.37; H, 6.73.
1H NMR (δ, CD2Cl2, 20 °C): 7.90-7.10 (m, 10H), 2.88 (s, 3H),
2.83 (s, 3H), 2.80-1.70 (m, 4H), 1.41 (d, 15H, J HP ) 1.6 Hz).
13C{1H} NMR (δ, CDCl3, 20 °C): 135.9 (d, J CP ) 12.2 Hz), 132.5
(d, J CP ) 10.8 Hz), 129.5 (d, J CP ) 76.3 Hz), 128.4, 128.2, 81.8
(d, J CP ) 2.9 Hz, C5Me5), 61.5 (d, J CP ) 8.6 Hz, NCH2), 55.2
(NMe), 53.3 (NMe), 32.0 (d, J CP ) 16.7 Hz, PCH2), 10.5 (C5Me5).
31P{1H} NMR (δ, CDCl3, 20 °C): 60.9. Single crystals were
obtained by slow diffusion of diethyl ether into a solution of 1
in CH2Cl2.
Ru Cp *(K1(P )-P h 2P CH2CH2NMe2)(Cl)(CO) (2). A solution
of 1 (0.20 g, 0.378 mmol) in CH2Cl2 (5 mL) was saturated with
CO and stirred for 24 h. On addition of diethyl ether (ca. 50
mL), a yellow precipitate was formed, which was collected on
a glass frit, washed with diethyl ether, and dried under
-
showing the slow formation of 5 (with CF3SO3 as the
counterion). The reaction was complete within about 5 h.
Ca ta lytic Cyclotr im er iza tion of HCtCCOOEt a n d
Dim er iza tion of HCtCR (R ) P h , SiMe3, a n d n -Bu ). In
a typical procedure, alkynes (0.3 M) were added to a suspen-
sion of 1 (2 mol %) in toluene (5 mL), and the sealed Schlenk
tube was heated in an oil bath for 20 h (R ) COOEt, Ph, SiMe3,
n-Bu, CH2OH) at 111 °C. After that time, the reaction mixture
was evaporated to dryness under vacuum, and the coupling
products were extracted with n-hexane. The solvent was again
removed under vacuum, affording isomeric mixtures of cou-
pling products. The product distribution was determined by
1H NMR spectroscopy (see Supporting Information).
X-r a y Str u ctu r e Deter m in a tion for 1, 3, 4, a n d 5.
Crystal data and experimental details are given in Table 1.
X-ray data for 1, 3, and 4 were collected on a Philips PW 1100
four-circle diffractometer using graphite-monochromated Mo
KR (λ ) 0.710 73 Å) radiation and the θ-2θ scan technique.
For 5, a Siemens Smart CCD area detector diffractometer,
graphite-monochromated Mo KR radiation, a nominal crystal-
to-detector distance of 3.85 cm, and 0.3° ω-scan frames were
used. Corrections for Lorentz and polarization effects, for
crystal decay, and for absorption (5) were applied. The
structures were solved by Patterson or direct methods.5 All
non-hydrogen atoms were refined anisotropically, and hydro-
gen atoms were included in idealized positions (1, 3, 4) or were
refined without restraints (5).6 The structures were refined
against F2.
vacuum. Yield: 0.16 g (78%). Anal. Calcd for
C27H35-
ClNOPRu: C, 58.21; H, 6.33. Found: C, 58.62; H, 6.37. 1H
NMR (δ, CDCl3, 20 °C): 7.60-7.38 (m, 10H), 2.50-2.10 (m,
4H), 2.14 (s, 6H), 1.48 (s, 15H). 13C{1H} NMR (δ, CDCl3, 20
°C): 207.1 (d, J CP ) 20.8 Hz, CO), 132.9-128.6 (Ph), 96.6 (C5-
Me5), 54.9 (d, J CP ) 4.2 Hz, NCH2), 45.5 (NMe2), 29.2 (d, J CP
) 28.2 Hz, PCH2), 9.9 (C5Me5). 31P{1H} NMR (δ, CDCl3, 20
°C): 38.9. IR (diffuse reflectance, cm-1): 1912 (s, νCO).
Ru Cp *(K2(P ,N)-P h 2P CH2CH2NMe2)(η1-OSO2CF 3) (3). A
solution of 1 (0.25 g, 0.473 mmol) in tetrahydrofuran (5 mL)
was treated with TlCF3SO3 (0.17 g, 0.481 mmol) and stirred
for 30 min, whereupon the solution turned dark red and a
precipitate of TlCl was formed. Insoluble materials were
removed by filtration, and the solution was evaporated to
dryness, affording an orange solid, which was collected on a
glass frit, washed with diethyl ether, and dried under vacuum.
Yield: 0.24 g (80%). Anal. Calcd for C27H35F3NO3PSRu: C,
50.46; H, 5.49. Found: C, 50.62; H, 5.51. 1H NMR (δ, CD3-
NO2, 20 °C): 7.60-7.50 (m, 10H), 2.95-2.50 (m, 4H), 2.43 (s,
6H), 1.57 (d, 15H, J HP ) 1.8 Hz). 13C{1H} NMR (δ, CD3NO2,
20 °C): 134.0-130.1 (Ph), 90.2 (C5Me5), 53.8 (NMe), 30.7 (d,
J CP ) 23.4 Hz, PCH2), 10.2 (d, J CP ) 1.7 Hz, C5Me5). The
resonance of the NCH2 carbon atom is superimposed by the
solvent resonances. 31P{1H} NMR (δ, CD2Cl2, 20 °C): 61.1.
Single crystals suitable for X-ray crystallography were ob-
tained by slow diffusion of diethyl ether into a solution of 3 in
tetrahydrofuran.
Resu lts a n d Discu ssion
[Ru Cp *(K2(P ,N)-P h 2P CH2CH2NMe2)(dCdCHP h )](CF 3-
SO3) (4). To a solution of 3 (0.20 g, 0.311 mmol) in tetrahy-
drofuran (5 mL) was added HCtCPh (51 µL, 0.464 mmol) by
syringe, and the mixture was stirred for 15 min. On addition
of diethyl ether, a red precipitate was formed, which was
collected on a glass frit, washed with diethyl ether, and dried
Syn th esis of Ru Cp*(K2(P ,N)-P h 2P CH2CH2NMe2)Cl
(1). RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)Cl (1) is ob-
tained in 87% yield upon the reaction of RuCp*(η4-
isoprene)Cl with 1 equiv of Ph2PCH2CH2NMe2 in
(5) Sheldrick, G. M. SHELXS86, Program for the Solution of Crystal
Structures, University of Go¨ttingen, Germany, 1986.
(6) Sheldrick, G. M. SHELXL93, Program for Crystal Structure
Refinement, University of Go¨ttingen, Germany, 1993.
(3) Fagan, P. J .; Mahoney, W. S.; Calabrese, J . C.; Williams, I. D.
Organometallics 1990, 9, 1843.
(4) Smith, R. T.; Baird, M. C. Inorg. Chim. Acta 1982, 62, 135.

1958 Organometallics, Vol. 16, No. 9, 1997
Ta ble 1. Cr ysta llogr a p h ic Da ta for Com p lexes 1, 3, 4, a n d 5
Mauthner et al.
1
3
4
5
formula
fw
C26H35ClNPRu
529.04
C27H35F3NO3PRuS
642.66
C35H41F3NO3PRuS
744.79
C50H54BClNPRu
847.24
cryst size, mm
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
0.55 × 0.50 × 0.48
P212121 (No. 19)
19.152(3)
13.159(2)
10.391(2)
0.25 × 0.35 × 0.60
P1h (No. 2)
9.208(2)
10.659(3)
15.142(3)
89.66(1)
85.19(1)
80.05(1)
1458.6(6)
2
0.10 × 0.10 × 0.20
P21/c (No. 14)
8.720(4)
24.061(10)
17.483(8)
0.50 × 0.30 × 0.26
P21 (No. 4)
11.668(1)
13.450(1)
13.903(1)
103.59(2)
90.56(1)
2618.8(8)
4
1.342
295
0.774
none
3565(3)
4
1.387
297
0.593
none
2181.8(3)
2
1.290
298
0.492
empirical
0.77/1.00
27
-14 e h e 14
-17 e k e 12
-17 e l e 17
14651
6935
6373
506
0.0248
0.0297
0.0593
-0.36/0.37
Z
F
T, K
calc, g cm-3
1.463
296
0.711
none
µ, mm-1 (Mo KR)
absorption corr
transmiss factors, min/max
θ
max, deg
index ranges
25
25
20
0 e h e 22
0 e k e 15
0 e l e 12
2627
2627
2441
0 e h e 10
-12 e k e 12
-17 e l e 18
5147
5147
4521
335
0.0274
0.0352
0.0671
0 e h e 8
0 e k e 23
-16 e l e 16
3300
3319
1991
no. of reflns measd
no. of unique reflns
no. of reflns F > 4σ(F)
no. of params
277
368
R(F) (F > 4σ(F))a
0.0200
0.0238
0.0468
-0.29/0.21
0.0712
0.1340
0.1906
-0.43/0.52
R(F) (all data)a
wR(F2) (all data)a
diff Four peaks, min/max, e Å-3
-0.33/0.44
a
2
R ) ∑||Fo| - |Fc||/∑|Fo|, wR ) [∑(w(Fo - Fc2)2)/∑(w(Fo2)2)]1/2
.
CH2Cl2 as the solvent. 1 is a thermally robust orange
solid which is stable to air in the solid state but
decomposes in solution when exposed to air. Charac-
terization of 1 was done by a combination of elemental
1
analysis and H, 13C{1H}, and 31P{1H} NMR spectros-
copy.
The 1H NMR spectrum of 1 in CD2Cl2 exhibits a
doublet for the Cp* ring centered at 1.41 ppm (J HP
)
1.7 Hz). The NMe2 group of the Ph2PCH2CH2NMe2
ligand displays two singlets at 2.88 (3H) and 2.83 ppm
(3H), i.e., the methyl groups are diastereotopic. The 31P-
{1H} NMR spectrum exhibits a singlet at 60.9 ppm. In
the 13C{1H} NMR spectrum of 1, the resonances of the
Ph2PCH2CH2NMe2 ligand give rise to characteristic
doublets centered at 61.5 (J CP ) 8.6 Hz) and 32.0 ppm
(J CP ) 16.7 Hz), assigned to the NCH2 and PCH2
methylene protons, respectively, and two singlets at 55.2
and 55.3 ppm, assigned to the methyl groups. The
resonance of the ring carbon atoms of Cp* appears as a
doublet centered at 81.8 ppm (J CP ) 2.9 Hz), indicative
of the +II oxidation state of ruthenium. In addition, 1
was characterized by X-ray crystallography. A struc-
tural view of 1 is depicted in Figure 1. Selected bond
distances and angles are given in Table 2. 1 adopts the
usual “three-legged” piano stool structure. The Ru-P
and Ru-N distances are 2.289(1) and 2.260(2) Å,
respectively, with a P-Ru-N angle of 81.4(1)° (in
RuCp*(Me2NCH2CH2NMe2)Cl, the Ru-N distances are
2.262(4) and 2.295(4) Å).7 The Ru-Cl distance of 2.441-
(1) Å is in the range observed for other half-sandwich
ruthenium complexes in the same the formal oxidation
state.8
F igu r e 1. Stuctural view of RuCp*(κ2(P,N)-Ph2PCH2CH2-
NMe2)Cl (1).
reaction with carbon monoxide. Thus, when 1 is stirred
under a CO atmosphere for 24 h at ambient tempera-
ture, the Ru-N bond is cleaved to afford the neutral
complex RuCp*(κ1(P)-Ph2PCH2CH2NMe2)(Cl)(CO) (2) in
78% isolated yield (Scheme 1). Characterization of 2
was done by a combination of elemental analysis and
IR, 1H, 13C{1H}, and 31P{1H} NMR spectroscopy. In the
IR spectrum, the CO stretching frequency is observed
at 1912 cm-1. In the 13C{1H} NMR spectrum, the CO
ligand exhibits a characteristic low-intensity doublet
centered at 207.1 ppm (J CP ) 20.8 Hz). Due to the η1-
(P) coordination of the Ph2PCH2CH2NMe2 ligand, the
13C resonances of the NCH2 and NMe2 moieties are
significantly shifted to higher field (ca. 7 ppm NCH2,
ca. 10 ppm NMe2) compared to those of the η2-(P)-
coordinated Ph2PCH2CH2NMe2 ligand in 1. Moreover,
the methyl groups are no longer inequivalent showing
now a singlet resonance in both the 1H and 13C{1H}
NMR spectra.
Rea ction of 1 w ith CO. The hemilabile nature of
the Ph2PCH2CH2NMe2 ligand in 1 is revealed by the
(7) Wang, M. H.; Englert, U.; Koelle, U. J . Organomet. Chem. 1993,
453, 127.
(8) de Rios, I. los; Tenorio, M. J .; Padilla, J .; Puerta, M. C.; Valerga,
P. J . Chem. Soc., Dalton Trans. 1996, 377.

Study of RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)Cl
Organometallics, Vol. 16, No. 9, 1997 1959
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(d eg) for Com p lexes 1, 3, 4, a n d 5
1
3
4
5
Ru-C(1-5)av
Ru-P
2.180(4) 2.182(3) 2.268(7)
2.289(1) 2.319(1) 2.330(4)
2.260(2) 2.256(2) 2.217(10) 2.122(2)
2.250(3)
2.350(1)
Ru-N
Ru-Cl
2.441(1)
2.373(1)
Ru-O(1)
Ru-C(27)
Ru-C(25)
N-C(25)
N-C(26)
2.277(2)
1.81(2)
2.085(2)
1.396(4)
1.480(4)
1.465(5) 1.480(3) 1.51(2)
1.495(5) 1.481(3) 1.46(2)
P-Ru-N
81.4(1)
89.5(1)
84.5(1)
81.2(1)
81.4(3)
82.6(1)
87.7(1)
84.2(1)
P-Ru-Cl
N-Ru-Cl
N-Ru-O(1)
P-Ru-O(1)
P-Ru-C(27)
P-Ru-C(25)
Ru-C(27)-C(28)
79.4(1)
84.5(1)
90.7(4)
173(1)
85.6(1)
F igu r e 2. Structural view of RuCp*(κ2(P,N)-Ph2PCH2CH2-
NMe2)(η1-OSO2CF3) (3).
Sch em e 1
Å, respectively, with a P-Ru-N angle of 81.2(1)°. The
-
CF3SO3 anion is coordinated via the oxygen atom in
η1-fashion, with the Ru-O(1) distance and the Ru-
O(1)-S angle being 2.277(2) Å and 141.4(1)°, respec-
tively. Note that only a few ruthenium complexes with
the η1-OSO2CF3 ligand are known and structurally
characterized.9-12
Both 1 and 3 turned out to be excellent precursors
for the synthesis of cationic vinylidene complexes as
depicted in Scheme 2. The reaction of 1 with HCtCPh
in the presence of TlCF3SO3 in CH2Cl2 yields the
cationic vinylidene complex [RuCp*(κ2(P,N)-Ph2PCH2-
CH2NMe2)(dCdCHPh)]+ (4) in high yield as an air-
stable red solid. Similarly, treatment of 3 with 1 equiv
of HCtCPh in CH2Cl2 affords 4 in essentially quantita-
tive yield as monitored by 1H NMR spectroscopy,
attesting to the labile nature of the CF3SO3- ligand. The
molecular structure of 4 has been determined as shown
in Figure 3, with selected bond distances and angles
given in Table 2. The characteristic NMR spectroscopic
features comprise, in the 13C{1H} NMR spectrum, a
marked low-field resonance at 347.8 ppm (d, J CP ) 13.8
Hz) and a signal at 117.4 ppm assignable to the R- and
â-carbons of the vinylidene moiety, respectively. The
Câ-hydrogen atom gives rise to a doublet centered at
4.26 ppm (J HP ) 3.0 Hz). The ring carbon resonance of
the Cp* ring is low-field shifted, appearing at 102.6 ppm
(the respective resonances in 1 and 3 appear at 81.8 and
90.2 ppm, respectively), indicative of a higher oxidation
state of ruthenium. This is not surprising in view of
the strong π-acidity of the vinylidene ligand. Finally,
the resonances of the Ph2PCH2CH2NMe2 ligand are in
the expected ranges.
Sch em e 2
Rea ction of 1 w ith TlCF 3SO3 a n d HCtCP h .
Substitution of the Cl atom in 1 for the weakly nucleo-
philic CF3SO3 anion was investigated with the inten-
tion of generating a reactive complex bearing a weakly
coordinating ligand occupying a latent coordination site.
In fact, chloride abstraction from 1 with TlCF3SO3 (1
equiv) affords, on workup, the expected neutral complex
RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)(η1-OSO2CF3) (3),
-
-
The overall three-legged piano stool structure of 4 is
very similar to those of 1 and 3. The Ru-C(27) bond
distance is 1.81(2) Å, somewhat shorter than those in
other cationic vinylideneruthenium complexes.13 For
where CF3SO3 is directly bound to the metal center
(Scheme 2). This formulation corresponds with both the
elemental analysis and the close similarities between
the H and 13C{1H} NMR spectra of the 18e- complex
1
1. A structural view of 3 is depicted in Figure 2.
Important bond distances and angles are shown in Table
2. The overall geometry of the complex is very similar
to that observed for other three-legged piano stool
complexes. The Cp* ring is essentially planar, with
C-C bond distances in the range 1.402(4)-1.453(4) Å,
giving a mean value of 1.433 Å. The Ru-C distances
range from 2.147(3) to 2.233(3) Å (mean 2.182 Å). The
Ru-P and Ru-N distances are 2.319(1) and 2.256(2)
(9) Gemel, C.; Kalt, D.; Mereiter, K.; Sapunov, V. N.; Schmid, R.;
Kirchner, K. Organometallics 1997, 16, 427.
(10) Sutter, J .-P.; J ames, S. L.; Steenwinkel, P.; Karlen, T.; Grove,
D. M.; Veldman, N.; Smeets, W. J . J .; Spek, A. L.; van Koten, G.
Organometallics 1996, 15, 941.
(11) Kraakman, M. J . A.; Klerk-Engels, B. de; de Lange, P. P. M.;
Vrieze, K.; Smeets, W. J . J .; Spek, A. L. Organometallics 1992, 11,
3774.
(12) Plosser, P. W.; Gallucci, J . C.; Wojcicki, A. Inorg. Chem. 1992,
31, 2376.
(13) Bruce, M. I. Chem. Rev. 1991, 91, 197.

1960 Organometallics, Vol. 16, No. 9, 1997
Mauthner et al.
F igu r e 3. Structural view of [RuCp*(κ2(P,N)-Ph2PCH2-
-
CH2NMe2)(dCdCHPh)]CF3SO3 (4) (CF3SO3 omitted for
clarity).
Sch em e 3
F igu r e 4. Structural view of [RuCp*(κ3(P,N,C)-Ph2PCH2-
CH2N(CH2)Me)Cl]BPh4 (5) (BPh4 omitted for clarity).
-
) 9.5 Hz) and two singlet resonances at 2.93 (1H) and
2.57 ppm (3H), assignable to the geminal methylene
protons of a RuCH2N unit and a NMe group. Surpris-
ingly, no coupling is observed between the two geminal
hydrogen atoms of the metal-coordinated CH2 moiety;
moreover, only one of the two CH2 protons is coupled to
the phosphorus atom of the chelating ligand. The ring
carbon resonance of the Cp* ring is low-field shifted with
respect to 1, appearing at 102.8 ppm (d, J CP ) 2.3 Hz),
consistent with a higher oxidation state of the metal
center.
The structural identity of 5 was unequivocally proven
by X-ray crystallography. The result is depicted in
Figure 4 with important bond distances and angles
given in Table 2. Accordingly, 5 adopts a four-legged
piano stool conformation, with Cl and the novel triden-
tate ligand Ph2PCH2CH2N(Me)CH2 as the legs. The
Ph2PCH2CH2N(Me)CH2 moiety is coordinated via P, N,
and C. The Ru-P, Ru-N, and Ru-C(25) distances are
2.350(1), 2.122(2), and 2.085(2) Å, respectively. The
bond distances at the nitrogen atom are 1.396(4) Å to
C(25), 1.495(4) Å to C(24), and 1.480(4) Å to C(26). This
is consistent with a double bond between N and C(25).
However, both the nitrogen and the C(25) atoms show
distinctly pyramidal environments with respect to their
bonding partners (Figure 4). N deviates by 0.277(3) Å
from the plane C(24)-C(25)-C(26), and C(25) deviates
by 0.249(14) Å from the plane H(25a)-H(25b)-N (hy-
drogen atoms refined in positional parameters), both
pointing toward Ru. Thus, hybridization of N and C(25)
is between sp2 and sp3, and the bonding situation of the
Ph2PCH2CH2N(Me)CH2 ligand might be best described
as intermediate between the two limiting forms I and
II.
instance, in [RuCp(PMe3)2(dCdCHMe)]+ and [RuCp(Ph2-
PCH2CH2PPh2)(dCdCPh(C7H7))]+, the Ru-C distances
are 1.845(7) and 1.848(9) Å, respectively.14,15 The
RudCdC group is nearly linear, the angle Ru-C(27)-
C(28) being 173(1)°.
Rea ction of 1 w ith Na BP h 4 a n d CH2Cl2. Next we
performed chloride abstraction from 1 with NaBPh4
instead of TlCF3SO3 in CH2Cl2 as the solvent. Instead
of the expected cationic complex [RuCp*(κ2(P,N)-Ph2-
PCH2CH2NMe2)]+, however, the novel cationic Ru(IV)
complex [RuCp*(κ3(P,N,C)-Ph2PCH2CH2N(CH2)Me)Cl]+
(5) was formed in 80% yield (Scheme 3). This complex
is air stable both in solution and in the solid state.
Characterization was done by elemental analysis and
1H, 13C{1H}, and 31P{1H} NMR spectroscopy.
Accordingly, the 1H and 13C{1H} NMR spectra of 5
are quite different from those of complexes 1-4 and are
inconsistent with the presence of a bidentate P,N-
coordinated Ph2PCH2CH2NMe2 ligand as follows. There
is a substantial down-field shift for the PCH2 carbon
atom from about 31 ppm in complexes 1-4 to 22.0 ppm
(d, J CP ) 24.1 Hz) in 5. Furthermore, the 13C{1H} NMR
spectrum of 5 exhibits two singlets at 54.9 and 50.0 ppm
and a doublet centered at 52.3 ppm (J CP ) 5.5 Hz),
assignable to NCH2CH2P, NMe, and RuCH2N carbon
1
atoms, respectively. The H NMR spectrum of 5 exhib-
its a doublet resonance centered at 3.21 ppm (1H, J HP
A possible mechanism to account for the formation
of 5 is suggested in Scheme 3. 5 is formed after halide
abstraction in 1 with NaBPh4 in either CH2Cl2 or CD2-
Cl2 as the solvents. Likewise, 3 is quantitatively
(14) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J . Chem.
Soc., Dalton Trans. 1982, 2203.
(15) Bruce, M. I.; Humphrey, M. G.; Koutsantonis, G. A.; Liddell,
M. J . J . Organomet. Chem. 1987, 326, 247.

Study of RuCp*(κ2(P,N)-Ph2PCH2CH2NMe2)Cl
Organometallics, Vol. 16, No. 9, 1997 1961
1
converted in CD2Cl2 to 5, as monitored by H and 13C-
Ta ble 3. Con ver sion a n d P r od u ct Distr ibu tion of
th e Ca ta lytic Dim er iza tion a n d Cyclotr im er iza tion
of Ter m in a l Alk yn esa
{1H} NMR spectroscopy. In both cases, we assume that
the cationic 16e- complex [RuCp*(κ2(P,N)-Ph2PCH2CH2-
NMe2)]+ is intermediarily formed. Methyl â-hydrogen
elimination results in the formation of the cyclometa-
lated cationic hydrido complex [RuCp*(κ3(P,N,C)-Ph2-
PCH2CH2N(CH2)Me)H]+, which, although not detected
by NMR spectroscopy, is trapped in CH2Cl2 or CD2Cl2
as the chloro complex 5. It is worth noting that
activation of C-H bonds adjacent to nitrogen is rare,
in contrast to those adjacent to phosphorus.16 Known
R
I
II
III
IV
V
conversion
Ph
SiMe3
n-Bu
57
43
83
18
63
20
11
96
17
42
40
examples include only the activation of a NPri ligand
2
COOEt
50
50
in a dinuclear ruthenium complex17 and the activation
of tertiary amines by osmium cluster complexes.18 It
should further be mentioned that similar intramolecular
â-C-H eliminations are believed to be involved in the
chemical vapor deposition of amino and amido transition
metal complexes and in hydrodenitrogenation chemis-
try.19
a
Reactions were performed in boiling toluene for 20 h. Yields
are for isolated products. Product distribution has been deter-
mined by 1H NMR spectroscopy. All values are in percent.
to give 16e- alkynyl intermediates, which are trapped
in the presence of potential ligands such as CO, pyri-
dine, or CH3CN.20 Such intermediates have also been
suggested in the coupling reaction of terminal acetylenes
catalyzed by RuTp(PPh3)2Cl (Tp ) trispyrazolylborate)
and RuCp*(PR3)H3 (R ) Ph, Me, and Cy).21,22 In the
case of the cyclotrimerization, the reaction presumably
proceeds via a different pathway, likely involving met-
allacyclic intermediates. At present, however, the
mechanism of both reactions can only be speculated
upon. Further work is in progress and will be reported
in a forthcoming paper.
Ca ta lytic Cyclotr im er iza tion a n d Dim er iza tion
of Ter m in a l Acetylen es. Reaction of 1 with an excess
of HCtCR (R ) Ph, SiMe3, and n-Bu) in toluene at
reflux for 20 h results typically in isomeric mixtures of
head-to-head- and head-to-tail-coupled dimers in low to
moderate yields (Table 3). Both conversion and selec-
tivity vary drastically with the substituent. In the case
of R ) COOEt, however, exclusively cyclotrimerization
was observed, affording a 1:1 mixture of 1,2,4- and 1,3,5-
benzenetricarboxylic acid esters in 96% yield (Table 3).
For the mechanism of this process, it seems likely that
the catalytic dimerization of terminal alkynes is initi-
ated by a neutral vinylidene complex which is interme-
diarily formed. Subsequent HCl elimination affords a
16e- alkynyl catalyst. Such an elimination might be
facilitated due to the basic NMe2 group. In fact, it has
been shown recently that neutral vinylidene complexes
undergo 1,3-HCl eliminations on treatment with base
Ack n ow led gm en t. Financial support by the “J ubi-
la¨umsfond der O¨ sterreichischen Nationalbank” is grate-
fully acknowledged (Project 5305).
Su p p or tin g In for m a tion Ava ila ble: Listings of atomic
coordinates, anisotropic temperature factors, complete bond
lengths and angles, and least-squares planes for complexes 1,
3, 4, and 5 (42 pages). Ordering information is given on any
current masthead page.
(16) Crabtree, R. Angew. Chem. 1993, 105, 828. (b) Crabtree, R.
Chem. Rev. 1985, 85, 245.
OM9610408
(17) Kuhlman, R.; Folting, K.; Caulton, K. G. Organometallics 1995,
14, 3188.
(18) Adams, R. D.; Tanner, J . T. Appl. Organomet. Chem. 1992, 6,
449.
(19) (a) Hoffman, D. M. Polyhedron 1994, 13, 1169. (b) Fix, R. M.;
Gordon, R. G.; Hoffman, D. M. Chem. Mater. 1990, 2, 235.
(20) Bruce, M. I.; Hall, B. C.; Zaitseva, N. N.; Skelton, B. W.; White,
A. H. J . Organomet. Chem. 1996, 522, 307
(21) Slugovc, C.; Mereiter, K.; Zobetz, E.; Schmid, R.; Kirchner, K.
Organometallics 1996, 15, 5275.
(22) Yi, C. S.; Liu, N. Organometallics 1996, 15, 3968.