Protonation of a ruthenium vinylidene complex with a NO ligand leading to ruthenium vinyl complexes

Article abstract of DOI:10.1021/om900576h

Treatment of a ruthenium vinylidene complex bearing a bent-type NO ligand, RuCl(NO)(PPh₃)₂{=C=CH-(C₆H₄Me)} (1), with protic acids gave rise to the ruthenium vinyl complexes RuCl(X){(Z)-CH=CH(C₆H₄

Full text of DOI:10.1021/om900576h

Organometallics 2009, 28, 5587–5589 5587
DOI: 10.1021/om900576h
Protonation of a Ruthenium Vinylidene Complex with a NO Ligand
Leading to Ruthenium Vinyl Complexes
Yasuhiro Arikawa,*,† Hayato Yamasaki,† Mamoru Yamaguchi,† Keisuke Umakoshi,‡ and
Masayoshi Onishi‡
†Graduate School of Science and Technology and ‡Department of Applied Chemistry, Faculty of Engineering,
Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8521, Japan
Received July 4, 2009
Summary: Treatment of a ruthenium vinylidene complex
bearing a bent-type NO ligand, RuCl(NO)(PPh3)2{dCdCH-
(C6H4Me)} (1), with protic acids gave rise to the ruthenium
vinyl complexes RuCl(X){(Z)-CHdCH(C6H4Me)}(PPh3)2-
(NO) (X = Cl (2a), O2CCF3 (2b), FBF3 (2c)) with concomi-
tant transformation to linear-type NO. This indicates unusal
protonation at the vinylidene R-carbon and anion-part coordi-
nation of the protic acids to the ruthenium atom at the trans
position to the resulting vinyl group. The coordinated BF4
moiety of 2c was easily replaced to be a counteranion by
MeCN solvent molecules, yielding [RuCl{(Z)-CHdCH-
(C6H4Me)}(NCMe)(PPh3)2(NO)]BF4 (3).
polarized so that CR is electron-poor (δþ) and Cβ is electron-
rich (δ-); nucleophiles attack on CR, and addition of electro-
philes on Cβ are expected to take place.2 Thus, in general,
addition of a proton, a typical simple electrophile, would
afford the corresponding carbyne,3 although direct and/or
indirect (through metal center) protonation can occur. In
our continuing research of ruthenium nitrosyl complexes,4
recently we found ruthenium vinylidene complexes with a
bent-type NO, e.g. RuCl(NO)(PPh3)2{dCdCH(C6H4Me)}
(1), and their interesting [2 þ 2] cycloaddition reactions.4a
Here, we report protonation of the ruthenium vinylidene 1,
affording vinyl complexes but not carbyne species, with con-
comitant transformation to linear-type NO. Although Werner
and co-workers have reported that protonation of RuCl2-
(PCy3)2{dCdCH(Ph)} gave the five-coordinate ruthenium
carbyne [RuCl2{tCCH2(Ph)}(PCy3)2]þ,3e for the present sys-
tem, the use of various protic acids led us to the formation of
ruthenium vinyl species as another reaction course.
Transition-metal vinylidene species have brought about
diverse stoichiometric and catalytic transformations of or-
ganic molecules, through utilization of their electrophilically
active centers and alkene/alkyne metathesis activities.1 As is
commonly accepted for ruthenium, the vinylidene ligand is
Treatment of the ruthenium vinylidene 1 with aqueous
HCl afforded the six-coordinated vinyl complex RuCl2{(Z)-
CHdCH(C6H4Me)}(PPh3)2(NO) (2a) (Scheme 1). The IR
ν(NO) band (1851 cm-1) is shifted to higher frequency from
that of 1, indicating NO ligation in the linear mode. The X-
ray structural analysis of 2a revealed a mutual Z configura-
tion of the p-tolyl group and the Ru atom with respect to the
CdC double bond and also cis coordination of the (Z)-vinyl
group on ruthenium to the NO ligand (Figure 1). The N-O
*To whom correspondence should be addressed. E-mail: arikawa@
nagasaki-u.ac.jp.
(1) (a) Metal Vinylidenes and Allenylidenes in Catalysis; Bruneau, C.,
Dixneuf, P. H., Eds.; Wiley-VCH: Weinheim, Germany, 2008. (b) Werner, H.
Coord. Chem. Rev. 2004, 248, 1693–1702. (c) Valyaev, D. A.; Semeikin,
O. V.; Ustynyuk, N. A. Coord. Chem. Rev. 2004, 248, 1679–1692. (d)
Selegue, J. P. Coord. Chem. Rev. 2004, 248, 1543–1563. (e) Katayama, H.;
Ozawa, F. Coord. Chem. Rev. 2004, 248, 1703–1715. (f) Dragutan, V.;
Dragutan, I. Platinum Met. Rev. 2004, 48, 148–153. (g) Puerta, M. C.;
Valerga, P. Coord. Chem. Rev. 1999, 193 - 195, 977–1025.
(2) Bruce, M. I. In Metal Vinylidenes and Allenylidenes in Catalysis;
Bruneau, C., Dixneuf, P. H., Eds.; Wiley-VCH: Weinheim, Germany, 2008;
pp 1-60.
(3) For Ru complexes, see: (a) Beach, N. J.; Walker, J. M.; Jenkins,
H. A.; Spivak, G. J. J. Organomet. Chem. 2006, 691, 4147–4152. (b)
Beach, N. J.; Williamson, A. E.; Spivak, G. J. J. Organomet. Chem. 2005,
690, 4640–4647. (c) Jung, S.; Ilg, K.; Brandt, C. D.; Wolf, J.; Werner, H. Eur.
J. Inorg. Chem. 2004, 469–480. (d) Beach, N. J.; Jenkins, H. A.; Spivak,
˚
(1.138(4) A) distance and the Ru-N-O angle (170.1(3)°) are
similar to those of RuCl[C(COOMe)dCHC{dCH-
(C6H4Me)}]{P(C6H4Me)3}2(NO).4a No other stereoisomers
were detected on the basis of NMR spectra.
To make clear the position of the supplemented Cl ligand
in 2a derived from HCl, treatment of 1 with CF3COOH was
carried out, which gave the trifluoroacetato vinyl complex
RuCl(O2CCF3){(Z)-CHdCH(C6H4Me)}(PPh3)2(NO) (2b)
in 65% yield. From an X-ray analysis of 2b, the NO ligand
is transformed into the linear mode, which is supported by
the IR spectra, and the vinyl group is still in the Z config-
ꢀ
G. J. Organometallics 2003, 22, 5179–5181. (e) Gonzalez-Herrero, P.;
€
Weberndorfer, B.; Ilg, K.; Wolf, J.; Werner, H. Organometallics 2001, 20,
ꢀ
€
3672–3685. (f) Gonzalez-Herrero, P.; Weberndorfer, B.; Ilg, K.; Wolf, J.;
Werner, H. Angew. Chem., Int. Ed. 2000, 39, 3266–3269. (g) St€uer, W.;
Wolf, J.; Werner, H.; Schwab, P.; Schulz, M. Angew. Chem., Int. Ed. 1998,
37, 3421–3423.
˚
(4) (a) Yamaguchi, M.; Arikawa, Y.; Nishimura, Y.; Umakoshi, K.;
Onishi, M. Chem. Commun. 2009, 2911–2913. (b) Arikawa, Y.; Asayama,
T.; Tanaka, C.; Tashita, S.; Tsuji, M.; Ikeda, K.; Umakoshi, K.; Onishi, M.
Organometallics 2008, 27, 1227–1233. (c) Arikawa, Y.; Asayama, T.;
Itatani, K.; Onishi, M. J. Am. Chem. Soc. 2008, 130, 10508–10509. (d)
Arikawa, Y.; Ikeda, K.; Asayama, T.; Nishimura, Y.; Onishi, M. Chem. Eur.
J. 2007, 13, 4024–4036. (e) Arikawa, Y.; Asayama, T.; Moriguchi, Y.; Agari,
S.; Onishi, M. J. Am. Chem. Soc. 2007, 129, 14160–14161. (f) Arikawa, Y.;
Asayama, T.; Onishi, M. J. Organomet. Chem. 2007, 692, 194–200. (g)
Nishimura, Y.; Arikawa, Y.; Inoue, T.; Onishi, M. Dalton Trans. 2005, 930–
937. (h) Arikawa, Y.; Nishimura, Y.; Ikeda, K.; Onishi, M. J. Am. Chem. Soc.
2004, 126, 3706–3707. (i) Arikawa, Y.; Nishimura, Y.; Kawano, H.; Onishi,
M. Organometallics 2003, 22, 3354–3356.
uration. The C1-C2 (1.327(5) A) distance is typical for a
CdC double bond. It is noteworthy that the CF3COO-
anion coordinates to the ruthenium atom at the trans posi-
tion to the vinyl group. Thus, in the conversion of 1 to 2a, the
original Cl ligand of 1 was determined to remain at the
position trans to the NO ligand.
Moreover, we performed the reaction with a strong noncoor-
dinating acid, HBF4 Et2O. Reaction of 1 with HBF4 Et2O at
3
3
0 °C afforded RuCl(FBF3){(Z)-CHdCH(C6H4Me)}(PPh3)2-
(NO) (2c) in 82% yield. The IR spectrum shows the appearance
r
2009 American Chemical Society
Published on Web 08/26/2009
pubs.acs.org/Organometallics

5588 Organometallics, Vol. 28, No. 18, 2009
Arikawa et al.
Figure 1. Molecular structures of 2a-c and 3. Hydrogen atoms (except for vinyl protons), minor sets of the disordered atoms of 2b,c, and
˚
the BF4 counterion for 3 have been omitted for clarity. Selected bond distances (A) and angles (deg) are as follows. For 2a: Ru-Cl1 =
2.3787(11), Ru-Cl2=2.4923(13), N-O = 1.138(4), C1-C2 = 1.282(8); Ru-N-O = 170.1(3). For 2b: Ru-Cl1 = 2.3607(8), Ru-O2 =
2.215(2), N-O1=1.140(3), C1-C2=1.327(5); Ru-N-O1=178.1(3). For 2c: Ru-Cl1=2.334(2), Ru-F1 = 2.384(4), N-O = 1.149(9),
C1-C2 = 1.319(9); Ru-N-O = 174.3(5). For 3: Ru-Cl1=2.3605(13), Ru-N2 = 2.192(4), N-O=1.149(5), C1-C2=1.316(7);
Ru-N-O = 176.1(4).
Scheme 1. Protonation of Complex 1 and Subsequent Reaction
of Complex 2c with MeCN
Scheme 2. Proposed Formation Mechanism of Complex 2
hydride species, followed by insertion of the vinylidene
group into the Ru-H bond (Scheme 2). During this process,
the NO ligand was ingeniously transformed to properly
regulate the electron density of the ruthenium center. A
similar NO transformation has been also observed in the
[2 þ 2] cycloaddition reaction of 1 with alkynes.4a Subse-
quent anion-part coordination of the protic acids to the
resulting five-coordinated intermediates with a square-pyra-
midal geometry would give 2. The preference for the
Z configuration in the vinyl group has been reported in the
reaction of Rh(CtCPh){dCdCH(Ph)}(PiPr3)2 with HCl
at -40 °C.6
of a strong NtO band (1868 cm-1). The X-ray crystallographic
analysis of 2c reveals that the vinyl complex adopts a distorted
octahedral coordination geometry, where the BF4 anion co-
ordinates to the ruthenium at the position trans to the vinyl
-
˚
group. The Ru-F1 bond distance of 2.384(4) A is longer than
5
that of Ru(FBF3)(CO)(NO)(PtBu2Me)2 (2.298(2) A). The
˚
Experimental Section
FAB-MS spectrum of 2c does not show a parent molecular
ion signal, but it does have a fragmentation signal with a loss of
the BF4 group, indicating lability of the group. This was
confirmed by its replacement in 2c by MeCN solvent molecules.
All reactions were carried out under dinitrogen, and subse-
quent workup procedures were performed in air. The solvent
(CH2Cl2) was distilled from CaH2. The starting material RuCl-
(NO)(PPh3)2{dCdCH(C6H4Me)} (1) was prepared according
to the previously reported method.4a All other organic solvents
and reagents were commercially available and were used with-
out further purification. NMR spectra in CDCl3 were recorded
on Varian Gemini-300 and JEOL JNM-AL-400 spectrometers.
1H and 13C{1H} NMR chemical shifts are quoted with respect to
TMS and the solvent signals, respectively. 31P{1H} NMR
spectra are referenced to an external standard of 85% H3PO4.
Infrared spectra in KBr pellets were obtained on a JASCO FT-
IR-420 or FT-IR-4100 spectrometer. Fast atom bombardment
mass spectra (FAB-MS) were recorded on a JEOL JMS-700N
spectrometer. Elemental analyses (C, H, N) were performed on a
Perkin-Elmer 2400II elemental analyzer.
Complex 2c, generated in situ from the 1/HBF4 Et2O reaction
3
system, was allowed to react with MeCN to give [RuCl{(Z)-
CHdCH(C6H4Me)}(NCMe)(PPh3)2(NO)]BF4 (3). Although
the FAB-MS spectrum of 3 is almost same as that of 2c, an
-
X-ray analysis of 3 revealed that the coordinated BF4 anion
was replaced to be the counteranion by MeCN molecules.
As mentioned above, since β-carbons of vinylidene groups
are widely accepted to bear a δ- electric charge in late
transition metal complexes, protonation of vinylidene com-
plexes would afford carbyne species.3 However, this system,
producing the vinyl species, shows that incoming Hþ was
attached to the R-carbon of the vinylidene group. Although
conclusive mechanistic comments based on definite experi-
mental results about the formation of these vinyl species are
not available at the present stage, we favor a process invol-
ving initial protonation of the ruthenium center to generate
Preparation of RuCl2{(Z)-CHdCH(C6H4Me)}(PPh3)2(NO)
(2a). A mixture of concentrated aqueous HCl (83 μL, 1.00 mmol)
and CH2Cl2 (5 mL) was added dropwise to a solution of RuCl-
(NO)(PPh3)2{dCdCH(C6H4Me)} (1; 161 mg, 0.20 mmol) in
€
(6) (a) Schafer, M.; Wolf, J.; Werner, H. Dalton Trans. 2005, 1468–
(5) Ogasawara, M.; Huang, D.; Streib, W. E.; Huffman, J. C.;
Gallego-Planas, N.; Maseras, F.; Eisenstein, O.; Caulton, K. G.
J. Am. Chem. Soc. 1997, 119, 8642–8651.
€
1481. (b) Schafer, M.; Mahr, N.; Wolf, J.; Werner, H. Angew. Chem., Int. Ed.
1993, 32, 1315–1318.

Note
Organometallics, Vol. 28, No. 18, 2009 5589
CH2Cl2 (10 mL) at room temperature. The mixture was stirred
for 2 h and evaporated to dryness. Crystallization of the residue
from CH2Cl2/hexane gave RuCl2{(Z)-CHdCH(C6H4Me)}(PP-
h3)2(NO) (2a) as orange crystals (153 mg, 91%). IR: ν(NtO)
1851 (s) cm-1. 1H NMR: δ 7.77-7.72 (m, 12H, PPh3), 7.43-7.39
(m, 6H, PPh3), 7.34-7.30 (m, 12H, PPh3), 7.19 (dt, J = 10, 3.2 Hz,
1H, Ru-CH), 6.69 (d, J = 7.7 Hz, 2H, C6H4Me), 6.64 (d, J = 10
Hz, 1H, Ru-CHdCH), 6.27 (d, J = 7.8 Hz, 2H, C6H4Me), 2.24
(s, 3H, C6H4Me). 13C{1H} NMR: δ 157.6 (t, J=9.6 Hz, Ru-CH),
138.1 (s, C6H4Me), 135.2 (s, C6H4Me), 134.9 (t, J = 5.1 Hz, PPh3),
132.4 (t, J = 2.9 Hz, Ru-CHdCH), 130.4 (s, PPh3), 129.3 (t, J =
24 Hz, PPh3), 128.6 (s, C6H4Me), 128.2 (s, C6H4Me), 127.8 (t, J =
5.1 Hz, PPh3), 21.2 (s, C6H4Me). 31P{1H} NMR: δ 17.3 (s). FAB-
MS (m/z): 808.2 ([M - Cl]þ), 691.1 ([RuCl(PPh3)2(NO)]þ), 546.1
([M - PPh3 - Cl]þ), 394.0 ([Ru(PPh3)(NO)]þ). Anal. Calcd for
C45H39NCl2OP2Ru: C, 64.06; H, 4.66; N, 1.66. Found: C, 63.76;
H, 4.76; N, 1.62.
PPh3 and 1H of Ru-CH), 6.86 (d, J = 8.2 Hz, 1H, Ru-
CHdCH), 6.59 (d, J = 7.8 Hz, 2H, C6H4Me), 6.07 (d, J = 7.7
Hz, 2H, C6H4Me), 2.20 (s, 3H, C6H4Me). 13C{1H} NMR: δ 146.3
(br s, Ru-CH), 136.2 (s, C6H4Me), 135.6 (s, C6H4Me), 134.5 (t,
J = 5.3 Hz, PPh3), 134.2 (brs, Ru-CHdCH), 131.2 (s, PPh3),
128.6 (s, C6H4Me), 128.5 (t, J=5.3 Hz, PPh3), 128.3(s, C6H4Me),
127.5 (t, J = 25 Hz, PPh3), 21.2 (s, C6H4Me). 31P{1H} NMR: δ
19.1 (s). FAB-MS (m/z): 808.1 ([M - BF4]þ), 691.1 ([RuCl-
(PPh3)2(NO)]þ), 546.1 ([M - PPh3 - BF4]þ), 394.0 ([Ru(PP-
h3)(NO)]þ). Anal. Calcd for C45H39NBClF4OP2Ru: C, 60.38;
H, 4.39; N, 1.56. Found: C, 60.06; H, 4.69; N, 1.36.
Preparation of [RuCl{(Z)-CHdCH(C6H4Me)}(NCMe)(PP-
h3)2(NO)]BF4 (3). A CH2Cl2 (10 mL) solution of RuCl(NO)-
(PPh3)2{dCdCH(C6H4Me)} (1; 81 mg, 0.10 mmol) was treated
with HBF4 Et2O (14 μL, 0.10 mmol) at 0 °C. After additional
3
stirring for 2 h at room temperature, the mixture was evaporated
to dryness and washed with hexane. To a benzene (10 mL)
solution of the residue was added MeCN (16 μL, 0.30 mmol),
and the mixture was stirred overnight. The resulting precipitate
was washed with benzene and crystallized by MeCN/ether to
give [RuCl{(Z)-CHdCH(C6H4Me)}(NCMe)(PPh3)2(NO)]BF4
(3) as orange crystals (60 mg, 64%). IR: ν(NtO), ν(CtN) 1874
Preparation of RuCl(O2CCF3){(Z)-CHdCH(C6H4Me)}-
(PPh3)2(NO) (2b). Trifluoroacetic acid (7.6 μL, 0.099 mmol) in
CH2Cl2 (10 mL) was added dropwise to a solution of RuCl-
(NO)(PPh3)2{dCdCH(C6H4Me)} (1; 81 mg, 0.10 mmol) in
CH2Cl2 (10 mL) at 0 °C. After additional stirring for 1.5 h at
room temperature, the mixture was evaporated to dryness.
Crystallization of the residue from CHCl3/hexane gave RuCl-
(O2CCF3){(Z)-CHdCH(C6H4Me)}(PPh3)2(NO) (2b) as red
crystals (60 mg, 65%). IR: ν(NtO) 1851 (s); ν(CdO) 1665 (s)
cm-1. 1H NMR: δ 7.72-7.67 (m, 12H, PPh3), 7.47-7.43 (m, 6H,
PPh3), 7.38-7.34 (m, 12H of PPh3 and 1H of Ru-CH), 6.95 (d,
J = 10 Hz, 1H, Ru-CHdCH), 6.56 (d, J = 7.8 Hz, 2H, C6-
H4Me), 5.94 (d, J = 7.8 Hz, 2H, C6H4Me), 2.18 (s, 3H, C6-
H4Me). 13C{1H} NMR: δ 160.8 (q, J = 36 Hz, CF3CO), 151.3 (t,
J = 10 Hz, Ru-CH), 137.8 (s, C6H4Me), 135.2 (s, C6H4Me),
135.0 (t, J = 2.8 Hz, Ru-CHdCH), 134.6 (t, J = 5.3 Hz, PPh3),
130.7 (s, PPh3), 129.4 (t, J = 24 Hz, PPh3), 128.6 (s, C6H4Me),
128.4 (s, C6H4Me), 128.1 (t, J = 5.2 Hz, PPh3), 115.4 (q, J = 292
Hz, CF3), 21.2 (s, C6H4Me). 31P{1H} NMR: δ 19.1 (s). FAB-MS
(m/z): 886.2 ([M - Cl]þ), 808.2 ([M - O2CCF3]þ), 769.1 ([Ru-
(O2CCF3)(PPh3)2(NO)]þ), 656.2 ([Ru(PPh3)2(NO)]þ), 624.1
([M - PPh3 - Cl]þ), 546.1 ([M - O2CCF3 - Cl]þ), 394.0 ([Ru-
(s), 1857 (s) cm-1 1H NMR: δ 7.70-7.66 (m, 12H, PPh3),
.
7.54-7.50 (m, 6H, PPh3), 7.47-7.43 (m, 12H of PPh3 and 1H
of Ru-CH), 7.23 (d, J = 9.3 Hz, 1H, Ru-CHdCH), 6.45 (d,
J = 7.8 Hz, 2H, C6H4Me), 6.11 (d, J = 7.8 Hz, 2H, C6H4Me),
2.15 (s, 3H, C6H4Me), 1.72 (s, 3H, NCMe). 13C{1H} NMR: δ
148.2 (t, J = 9.8 Hz, Ru-CH), 136.5 (s, C6H4Me), 136.3 (br s,
Ru-CHdCH), 136.0 (s, C6H4Me), 134.4 (t, J = 5.1 Hz, PPh3),
131.4 (s, PPh3), 128.6 (t, J = 5.1 Hz, PPh3), 128.5 (s, C6H4Me),
127.9 (s, C6H4Me), 127.4 (t, J = 24 Hz, PPh3), 21.2 (s, C6H4Me),
2.5 (s, NCMe), signal of NCMe not exactly located, probably
because of overlapping. 31P{1H} NMR: δ 16.7 (s). FAB-MS
(m/z):808.2([M - BF4 - NCMe]þ), 691.1 ([RuCl(PPh3)2(NO)]þ),
656.2 ([Ru(PPh3)2(NO)]þ), 546.1 ([M - BF4 - NCMe - PP-
h3]þ), 394.1 ([Ru(PPh3)(NO)]þ). Anal. Calcd for C47H42N2-
BClF4OP2Ru: C, 60.30; H, 4.52; N, 2.99. Found: C, 60.18, H,
4.59; N, 2.88.
(PPh3)(NO)]þ). Anal. Calcd for C47H39NClF3O3P2Ru CHCl3:
3
Acknowledgment. This work was supported by
Grants-in-Aid for Scientific Research on Priority Areas
(No. 20037055, “Chemistry of Concerto Catalysis”) and
Young Scientists (B) (No. 20750048) from the Ministry of
Education, Culture, Sports, Science and Technology,
Japan.
C, 55.40; H, 3.87; N, 1.35. Found: C, 55.32; H, 3.92; N, 1.28.
Preparation of RuCl(FBF3){(Z)-CHdCH(C6H4Me)}(PPh3)2-
(NO) (2c). A CH2Cl2 (10 mL) solution of RuCl(NO)(PPh3)2-
{dCdCH(C6H4Me)} (1; 81 mg, 0.10 mmol) was treated with
HBF4 Et2O (14 μL, 0.10 mmol) at 0 °C. After additional stirring
3
for 2 h at room temperature, the mixture was evaporated to
dryness and washed with hexane. The residue was crystallized by
slow evaporation of a CH2Cl2/toluene solution to give RuCl-
(FBF3){(Z)-CHdCH(C6H4Me)}(PPh3)2(NO) (2c) as red crystals
(73 mg, 82%). IR: ν(NtO) 1868 (s) cm-1. 1H NMR: δ 7.67-7.62
(m, 12H, PPh3), 7.52-7.48 (m, 6H, PPh3), 7.42-7.39 (m, 12H of
Supporting Information Available: Text, tables, and CIF files
giving X-ray crystallographic data for 2a, 2b CHCl3,
3
2c 2C6H5Me, and 3. This material is available free of charge
3
via the Internet at http://pubs.acs.org.