Synthesis and characterization of bimetallic ruthenium complexes bridged with C5H and related ligands

Article abstract of DOI:10.1021/om970051d

Treatment of [(η⁵-C₅R₅)Ru(L)₂]BF₄ (R = Me, (L)₂ = dppe; R = H, (L)₂ = (PPh₃)₂) with 0.45 equiv of HC≡CCH(OH)C≡CH led to the formation of the C₅H<

Full text of DOI:10.1021/om970051d

2940
Organometallics 1997, 16, 2940-2947
Syn th esis a n d Ch a r a cter iza tion of Bim eta llic Ru th en iu m
Com p lexes Br id ged w ith C5H a n d Rela ted Liga n d s
Hai Ping Xia, Wan Fung Wu, Weng Sang Ng, Ian D. Williams, and Guochen J ia*
Department of Chemistry, The Hong Kong University of Science & Technology,
Clear Water Bay, Kowloon, Hong Kong
Received J anuary 27, 1997X
Treatment of [(η5-C5R5)Ru(L)2]BF4 (R ) Me, (L)2 ) dppe; R ) H, (L)2 ) (PPh3)2) with 0.45
equiv of HCtCCH(OH)CtCH led to the formation of the C5H2-bridged compounds [(η5-
C5R5)(L)2RudCdCdCHCHdCdRu(L)2(η5-C5R5)](BF4)2. The C5H2-bridged compounds reacted
with alumina to give the C5H-bridged compounds [(η5-C5R5)(L)2RudCdCdCHCtCRu(L)2-
(η5-C5R5)]BF4. The structure of the C5H-bridged complex [Cp(PPh3)2RudCdCdCHCtCRu-
(PPh3)2Cp]BPh4 has been confirmed by X-ray diffraction and shows the bridging C5H ligand
to be symmetric with a delocalized π-system. Reaction of [(η5-C5R5)(L)2RudCdCdCHCtCRu-
(L)2(η5-C5R5)]BF4 with acetone in the presence of KOH or KOBut produced (η5-C5R5)(L)2-
RuCtCCH(CH2COMe)CtCRu(L)2(η5-C5R5).
In tr od u ction
Despite the fact that a large number of conjugated
bimetallic organometallic complexes have been reported,
there are still very limited bimetallic complexes with
conjugated hydrocarbon chains of odd numbers of carbon
atoms linking two metal centers. To this end, we have
investigated the reactions of HCtCCH(OH)CtCH with
[CpRu(PPh3)2]+ and [Cp*Ru(dppe)]+. Reactions of
1-alkynols with [(C5R5)Ru(L)2]+ and other coordinatively
unsaturated ruthenium(II) complexes have been inten-
sively studied.9 These reactions can lead to the forma-
tion of hydroxyvinylidenes,10 allenylidenes,11-14 vinylvi-
nylidenes,15 and other unusual coupling products,16
Bimetallic organometallic compounds with π-conju-
gated bridges have recently attracted considerable at-
tention, because of their unusual intrinsic chemical,
physical, and material properties.1,2 A large number of
interesting conjugated organometallic bimetallic com-
plexes without metal-metal bonding have been re-
ported, including those with Cx-bridged complexes Ln-
MCxM′Ln′,3,4 (CH)x-bridged complexes,5 C4R2-bridged
complexes with MtC linkages such as [(Me3SiNCH2-
CH2)3N]MotCCHdCHCtMo[N(CH2CH2NSiMe3)3]6 or
complexes with MdC linkages such as [(C5H4SiMe3)2-
(CO)NbdCdCMe-CMedCdNb(CO)(C5H 4SiMe3)2]-
(BPh4)2,7 and 1,3-bimetalated cyclobutenylidene (C4R3)
complexes.8
(5) (a) Sponsler, M. B. Organometallics 1995, 14, 1920 and refer-
ences therein. (b) Etzenhouser, B. A.; Chen, Q.; Sponsler, M. B.
Organometallics 1994, 13, 4176. (c) Etzenhouser, B. A.; Cavanaugh,
M. D.; Spurgeon, H. N.; Sponsler, M. B. J . Am. Chem. Soc. 1994, 116,
2221. (d) Lemke, F. R.; Szalda, D. J .; Bullock, R. M. J . Am. Chem.
Soc. 1991, 113, 8466. (e) Bullock, R. M.; Lemke, F. R.; Szalda, D. J . J .
Am. Chem. Soc. 1990, 112, 3244. (f) Fox, H. H.; Lee, J . K.; Park, L. Y.;
Schrock, R. R. Organometallics 1993, 12, 759. (g) Rajapakse, N.; J ames,
B. R.; Dolphin, D. Can. J . Chem. 1990, 68, 2274.
(6) (a) Shih, K. Y.; Schrock, R. R.; Kempe, R. J . Am. Chem. Soc.
1994, 116, 8804. (b) Krouse, S. A.; Schrock, R. R. J . Organomet. Chem.
1988, 355, 257. (c) Ustynyuk, N. A.; Vinogradova, V. N.; Andrianov,
V. G.; Struchkov, Yu. T. J . Organomet. Chem. 1984, 268, 73.
(7) (a) Antin˜olo, A.; Otero, A.; Fajardo, M.; Garcˆıa-Yebra, C.; Gil-
Sanz, R.; Lo´pez-Mardomingo, C.; Martˆın, A.; Gomez-Sal, P. Organo-
metallics 1994, 13, 4679. (b) Rappert, T.; Nu¨rnberg, O.; Werner, H.
Organometallics 1993, 12, 1359. (c) Beddoes, R. L.; Bitcon, C.; Ricalton,
A.; Whiteley, M. W. J . Organomet. Chem. 1989, 367, C21. (d) Iyer, R.
S.; Selegue, J . P. J . Am. Chem. Soc. 1987, 109, 910. (e) Bruce, M. I.;
Koutsantonis, G. A.; Liddell, M. J .; Tiekink, R. T. J . Organomet. Chem.
1991, 420, 253.
(8) See for example: (a) Fisher, H.; Leroux, F.; Roth, G.; Stumpf,
R. Organometallics 1996, 15, 3723 and references therein. (b) Davison,
A.; Solar, J . P. J . Organomet. Chem. 1978, 155, C8. (c) Kolobova, N.
Ye.; Skripkin, V. V.; Alexandrov, G. G.; Struchkov, Yu. T. J . Organomet.
Chem. 1979, 169, 293.
(9) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197 and references therein.
(b) Bruce, M. I.; Swincer, A. G. Adv. Organomet. Chem. 1983, 22, 59.
(10) Le Lagadec, R.; Roman, E.; Toupet, L.; Muller, U.; Dixneuf, P.
H. Organometallics 1994, 13, 5030.
X Abstract published in Advance ACS Abstracts, May 15, 1997.
(1) See for example: (a) Long, N. J . Angew. Chem., Int. Ed. Engl.
1995, 34, 21 and references therein. (b) Laine, R. M.; Viney, C. In
Inorganic and Organometallic Polymers with Special Properties; Laine,
R. M., Ed.; Kluwer Academic: Dordrecht, The Netherlands, 1991; p
413.
(2) (a) Bunz, U. H. F. Angew. Chem., Int. Ed. Engl. 1996, 35, 969.
(b) Lotz, S.; Van Rooyen, P. H.; Meyer, R. Adv. Organomet. Chem. 1995,
37, 219. (c) Ward, M. D. Chem. Soc. Rev. 1995, 121. (d) Lang, H. Angew.
Chem., Int. Ed. Engl. 1994, 33, 547. (e) Beck, W.; Niemer, B.; Wieser,
M. Angew. Chem., Int. Ed. Engl. 1993, 32, 923. (f) Holton, J .; Lappert,
M. F.; Pearce, R.; Yarrow, P. I. W. Chem. Rev. 1983, 83, 135.
(3) (a) Weng, W.; Bartik, T.; Gladysz, J . A. Angew. Chem., Int. Ed.
Engl. 1994, 33, 2199. (b) Brady, M.; Weng, W.; Gladysz, J . A. J . Chem.
Soc., Chem. Commun. 1994, 2655. (c) Zhou, Y.; Seyler, J . W.; Weng,
W.; Arif, A. M.; Gladysz, J . A. J . Am. Chem. Soc. 1993, 115, 8509. (d)
Seyler, J . W.; Weng, W.; Zhou, Y.; Gladysz, J . A. Organometallics 1993,
12, 3802. (e) Weng, W.; Ramsden, J . A.; Arif, A. M.; Gladysz, J . A. J .
Am. Chem. Soc. 1993, 115, 3824. (f) Weng, W.; Bartik, T.; Brady, M.;
Bartik, B.; Ramsden, J . A.; Arif, A. M.; Gladysz, J . A. J . Am. Chem.
Soc. 1995, 117, 11922 and references therein. (g) Bartik, T.; Bartik,
B.; Brady, M.; Dembinski, R.; Gladysz, J . A. Angew. Chem., Int. Ed.
Engl. 1996, 35, 414.
(4) See for example: (a) Coat, F.; Lapinte, C. Organometallics 1996,
15, 477. (b) Le Narvor, N.; Lapinte, C. J . Chem. Soc., Chem. Commun.
1993, 357. (c) Le Narvor, N.; Toupet, L.; Lapinte, C. J . Am. Chem.
Soc, 1995, 117, 7129. (d) Bruce, M. I.; Hinterding, P.; Tiekink, E. R.
T.; Skelton, B. W.; White, A. H. J . Organomet. Chem. 1993, 450, 209.
(e) Caulton, K. G.; Cayton, R. H.; Chisholm, M. H.; Huffman, J . C.;
Lobkovsky, E. B.; Xue, Z. Organometallics 1992, 11, 321. (f) Crescenzi,
R.; Lo Sterzo, C. Organometallics 1992, 11, 4301. (g) Koutsantonis, G.
A.; Selegue, J . P. J . Am. Chem. Soc. 1991, 113, 2316. (h) Stang, P. J .;
Tykwinski, R. J . Am. Chem. Soc. 1992, 114, 4411. (i) Fyfe, H. B.;
Mlekuz, M.; Zargarian, D.; Taylor, N. J .; Marder, T. B. J . Chem. Soc.,
Chem. Commun. 1991, 188. (j) Heidrich, J .; Steimann, M.; Appel, M.;
Beck, W.; Phillips, J . R.; Trogler, W. C. Organometallics 1990, 9, 1296.
(k) Gilbert, T. M.; Roger, R. D. J . Organomet. Chem. 1991, 421, C1. (l)
Frank, K. G.; Selegue, J . P. J . Am. Chem. Soc. 1990, 112, 6414.
(11) Selegue, J . P. Organometallics 1982, 1, 217.
(12) (a) Touchard, D.; Pirio, N.; Dixneuf, P. H. Organometallics 1995,
14, 4920. (b) Pirio, N.; Touchard, D.; Toupet, L.; Dixneuf, P. H. J . Chem.
Soc., Chem. Commun. 1991, 980. (c) Pirio, N.; Touchard, D.; Dixneuf,
P. H. J . Organomet. Chem. 1993, 462, C18. (d) Touchard, D.; Morice,
C.; Cadierno, V.; Haquette, P.; Toupet, L.; Dixneuf, P. H. J . Chem.
Soc., Chem. Commun. 1994, 859. (e) Wolinska, A.; Touchard, D.;
Dixneuf, P. H. J . Organomet. Chem. 1991, 420, 217.
(13) (a) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Gonza´lez-Cueva,
M.; Lastra, E.; Borge, J .; Garc´ıa-Granda, S.; Pe´rez-Carren˜o, E. Orga-
nometallics 1996, 15, 2137. (b) Cadierno, V.; Gamasa, M. P.; Gimeno,
J .; Lastra, E. J . Organomet. Chem. 1994, 474, C27.
S0276-7333(97)00051-4 CCC: $14.00 © 1997 American Chemical Society

Dimeric Ruthenium Complexes Bridged with C5H
Organometallics, Vol. 16, No. 13, 1997 2941
added to complete the precipitation. The deep purple solid
was collected by filtration, washed with hexane (10 mL) and
ether (10 mL), and then dried under vacuum. Yield: 0.16 g,
76%. Anal. Calcd for C87H72B2F8P4Ru2: C, 64.62; H, 4.49.
Found: C, 64.39; H, 4.57. 1H NMR (CD2Cl2): δ 8.30 (d, 3J (HH)
) 11.7 Hz, 1 H, RudCdCdCH), 7.53-6.88 (m, 60 H, 12 Ph),
5.98 (d, 3J (HH) ) 11.7 Hz, 1 H, RudCdCH), 5.43 (s, 5 H, Cp),
4.97 (s, 5 H, Cp). 31P{1H} NMR (CD2Cl2): δ 46.7 (s), 37.6 (s).
13C{1H} NMR (CD2Cl2): δ 359.1 (t, J (PC) ) 15.1 Hz,
RudCdCH), 282.4 (t, J (PC) ) 19.2 Hz, RudCdCdCH), 191.1
(s, RudCdCdCH), 138.0 (s, RudCdCdCH), 134.3 (s, RudCd
CH), 121.6-135.8 (m, Ph), 97.3 (s, Cp), 92.3 (s, Cp).
depending on the auxiliary ligands and alkynols. Thus,
bimetallic complexes bridged with hydrocarbon chains
of five carbon atoms may be produced from the reactions
of HCtCC(OH)CtCH with [CpRu(PPh3)2]+ and [Cp*Ru-
(dppe)]+. Here we wish to report the synthesis, char-
acterization, and properties of interesting bimetallic
complexes derived from these reactions, including C5H2-
and C5H-bridged complexes. A preliminary account of
this work has been published.17
Exp er im en ta l Section
[Cp *(d p p e)R u dCdCdCH CtCR u (d p p e)Cp *]BF 4 (5).
Meth od A. A 5 g amount of neutral alumina was added to a
purple solution of 3 (1.0 g, 0.66 mmol) in 25 mL of CH2Cl2.
The reaction mixture turned blue immediately. The alumina
was removed by filtration and washed with CH2Cl2 to give a
deep blue solution. The solvent was then removed completely
under vacuum to give a blue solid. Yield: 0.81 g, 86%. Anal.
Calcd for C77H79BF4P4Ru2: C, 65.25; H, 5.62. Found: C, 65.16;
H, 5.60. IR (KBr, cm-1): 3056 (w), 2903 (w), 1881 (s), 1575
(w), 1437 (m), 1096 (m), 1029 (m), 698 (m), 533 (m). UV-vis
(CH2Cl2): λmax (ꢀ) 630 (5.8 × 104 M-1 cm-1), 230 nm (8.0 × 104
M-1 cm-1). 1H NMR (CDCl3): δ 7.05-7.48 (m, 41 H, 8 Ph,
C5H), 2.30-2.74 (m, 8 H, 4 CH2), 1.51 (s, 30 H, 10 CH3). 31P-
{1H} NMR (CDCl3): δ 78.4 (s). 13C{1H} NMR (CDCl3): δ 225.6
(t, J (PC) ) 20.9 Hz, C(R)), 163.1 (s, C(â)), 128.5 (s, C(γ)), 135.8-
127.6 (m, Ph), 97.5 (s, C5Me5), 29.8-29.2 (m, CH2), 9.7 (s,
C5Me5).
All manipulations were carried out under a nitrogen atmo-
sphere using standard Schlenk techniques. Solvents were
distilled under nitrogen from sodium-benzophenone (hexane,
ether, THF, benzene) or calcium hydride (CH2Cl2). The
starting materials Cp*RuCl(dppe),18 CpRuCl(PPh3)2,19 and
HCtCC(OH)CtCH20 were prepared according to literature
methods. All other reagents were used as purchased from
Aldrich Chemical Co.
Microanalyses were performed by M-H-W Laboratories
(Phoenix, AZ). 1H, 13C{1H}, and 31P{1H} NMR spectra were
collected on a J EOL EX-400 spectrometer (400 MHz) or a
Bruker ARX-300 spectrometer (300 MHz). 1H and 13C NMR
chemical shifts are relative to TMS, and 31P NMR chemical
shifts are relative to 85% H3PO4. IR spectra were collected
on a Perkin-Elmer 1600 spectrometer. UV-vis spectra were
recorded on a Milton Roy Spectronic 3000 spectrometer.
[Cp *(d p p e)R u dCdCdCHCH dCdR u (d p p e)Cp *](BF 4)2
(3). AgBF4 (0.292 g, 1.49 mmol) was added to a solution of
Cp*RuCl(dppe) (1.00 g, 1.50 mmol) in THF (50 mL). The
reaction mixture was stirred for 1 h to give an orange solution.
Addition of HCtCCH(OH)CtCH (54 mg, 0.67 mmol) to the
orange solution produced a purple solution. The solution was
stirred for a further 1 h at room temperature, and then the
solvent was removed under vacuum to give a purple solid. The
solid was extracted with CH2Cl2 (5 mL). Addition of 30 mL of
ether to the CH2Cl2 solution yielded a purple precipitate. The
purple solid was collected by filtration, washed with ether, and
then dried under vacuum. Yield: 0.83 g, 74%. Anal. Calcd
for C77H80B2F8P4Ru2: C, 61.45; H, 5.36. Found: C, 61.39; H,
5.50. IR (KBr, cm-1): 3055 (w), 2909 (w), 1953 (s), 1881 (m),
1627 (w), 1529 (s), 1438 (s), 1168 (m), 1061 (s). UV-vis (CH2-
Cl2): λmax(ꢀ) 528 (4.2 × 104 M-1 cm-1), 230 nm (7.8 × 104 M-1
cm-1). 1H NMR (CDCl3): δ 7.03-7.80 (m, 40 H, 8 Ph), 6.01
Meth od B. A purple CH2Cl2 solution (5 mL) of crude 3 (ca.
3.00 mmol) prepared from the reactions of [Cp*Ru(dppe)]BF4
and HCtCCH(OH)CtCH was loaded onto a column of neutral
alumina (20 cm). The column was eluted with CH2Cl2/acetone
(5:1) to give a blue solution. The solvents of the blue solution
were removed under vacuum to give a blue solid. The solid
was collected by filtration, washed with ether (20 mL) and
hexane (20 mL), and dried under vacuum to give 1.2 g (58%)
of pure 5 as indicated by NMR.
After the blue compound 5 was eluted, the column was
further washed with acetone to give a brown solution. The
solvent of the brown solution was removed under vacuum to
give a yellowish brown solid, which was identified as [Cp*Ru-
(CO)(dppe)]BF4 (7; 95 mg, 4.2% yield). Anal. Calcd for
C
37H39BF4OP2Ru: C 59.29; H, 5.25. Found: C, 59.09; H, 5.46.
IR (KBr, cm-1): 1975 (s) [ν(CtO)]. 1H NMR (CDCl3): δ 7.08-
7.58 (m, 20 H, 4 Ph), 2.60-2.80 (m, 4 H, CH2), 1.62 (m, 15 H,
5 CH3). 31P{1H} NMR (CDCl3): δ 70.4 (s). 13C{1H} NMR
(CDCl3): δ 202.7 (t, J (PC) ) 16.0 Hz, CtO), 132.3-128.7 (m,
Ph), 99.4 (s, C5Me5), 29.6-30.2 (m, CH2), 9.6 (s, C5Me5).
3
3
(d, J (HH) ) 11.7 Hz, 1 H, RudCdCdCH), 3.90 (d, J (HH) )
11.7 Hz, 1 H, RudCdCH), 2.40-2.70 (m, 8 H, 4 CH2), 1.63 (s,
15 H, 5 CH3), 1.49 (s, 15 H, 5 CH3). 31P{1H} NMR (CDCl3): δ
76.9 (s), 67.5 (s). 13C{1H} NMR (CDCl3): δ 353.7 (t, J (PC) )
15.6 Hz, RudCdCH), 281.1 (t, J (PC) ) 19.6 Hz, RudCdCdCH),
188.9 (s, RudCdCdCH), 132.8 (s, RudCdCdCH), 128.1 (s,
RudCdCH), 135.3-128.9 (m, Ph), 106.0 (s, C5Me5), 101.7 (s,
C5Me5), 30.2-28.7 (m, CH2), 10.7 (s, C5Me5), 10.5 (s, C5Me5).
[Cp (P P h 3)2R u dCdCdCH CH dCdR u (P P h 3)2Cp ](BF 4)2
(4). To a blue solution of 6 (0.20 g, 0.13 mmol) in 5 mL of
CH2Cl2 was added 1 equiv of HBF4‚Et2O to give a purple
solution. The volume of the reaction mixture was reduced
until a purple solid began to form, and ether (20 mL) was then
[Cp (P P h 3)2Ru dCdCdCHCtCRu (P P h 3)2Cp ]BF 4 (6). To
a solution of CpRuCl(PPh3)2 (1.10 g, 1.53 mmol) in THF (10
mL)/CH2Cl2 (10 mL) was added AgBF4 (301 mg, 1.51 mmol).
The reaction mixture was stirred for a further 15 min to give
a brown solution. Addition of HCtCCH(OH)CtCH (55 mg,
0.69 mmol) to the reaction mixture produced a purple solution
immediately. The solution was stirred for an additional 15
min at room temperature. The solvent of the reaction mixture
was removed under vacuum, and the purple residue was
extracted with CH2Cl2 to give a purple solution. The purple
solution was passed through a column of neutral alumina (10
cm) using CH2Cl2/acetone (8:1) as the eluent to give a blue
solution. The volume of the blue solution was reduced under
vacuum until a blue solid formed, and ether (20 mL) was added
to complete the precipitation. The blue solid was collected by
filtration, washed with ether (20 mL), and hexane (20 mL) and
then dried under vacuum. Yield: 0.70 g, 61%. Anal. Calcd
for C87H71BF4P4Ru2: C, 68.33; H, 4.68. Found: C, 68.19; H,
5.06. IR (KBr, cm-1): 3052 (w), 1881 (s), 1572 (w), 1481 (m),
1435 (m), 1091 (m). UV-vis (CH2Cl2): λmax (ꢀ) 600 (7.2 × 104
M-1 cm-1), 230 nm (6.8 × 104 M-1 cm-1). 1H NMR (CD2Cl2):
(14) Matsuzaka, H.; Takagi, Y.; Hidai, M. Organometallics 1994,
13, 13.
(15) Selegue, J . P.; Young, B. A.; Logan, S. L. Organometallics 1991,
10, 1972.
(16) (a) Selegue, J . P. J . Am. Chem. Soc. 1983, 105, 5921. (b)
Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Lastra, E.; Borge, J .; Garcˆıa-
Granda, S. Organometallics 1994, 13, 745. (c) Matsuzaka, H.; Koizumi,
H.; Takagi, Y.; Nishio, M.; Hidai, M. J . Am. Chem. Soc. 1993, 115,
10396.
(17) J ia, G.; Xia, H. P.; Wu, W. F.; Ng, W. S. Organometallics 1996,
15, 3634.
(18) Oshima, N.; Suzuki, H.; Moro-oka, Y. Chem. Lett. 1984, 1161.
(19) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R.; Ittel, S.
D. Inorg. Synth. 1990, 28, 270.
(20) J ones, E. R. H.; Lee, H. H.; Whiting, M. C. J . Chem. Soc. 1960,
3483.
5
δ 7.88 (quintet, J (PH) ) 1.1 Hz, 1 H, -CHd), 7.33-7.13 (m,
60 H, 12 Ph), 4.72 (s, 10 H, 2 Cp). 31P{1H} NMR (CD2Cl2): δ

2942 Organometallics, Vol. 16, No. 13, 1997
Xia et al.
46.8 (s). 13C{1H} NMR (CD2Cl2): δ 228.5 (t, 2J (PC) ) 21.7 Hz,
C(R)), 168.5 (s, C(â)), 133.1 (s, C(γ)), 136.9-127.8 (m, Ph), 89.3
(s, Cp).
Ta ble 1. Cr ysta l Da ta a n d Refin em en t Deta ils for
[Cp (P P h 3)2Ru dCdCdCHCtCRu (P P h 3)2Cp ]-
BP h 4‚CH2Cl2‚Et2O
Air Oxid a t ion of [Cp *(d p p e)R u dCdCdCH CtCR u -
(d p p e)Cp *]BF 4. An appropriate amount of complex 5 was
dissolved in CDCl3 in an NMR tube. After 31P and 1H NMR
spectra of the solution were collected, the solution in the NMR
tube was exposed to air. 31P and 1H NMR spectra of the
sample were collected again after the solution was exposed to
air for 1 day, 2 days, 3 days, 5 days, 1 week, and 2 weeks. The
experiment showed that the intensities of the signals due to
complex 5 gradually decreased and those due to [Cp*Ru(CO)-
(dppe)]BF4 (7) gradually increased. Complex 7 appeared to
be the predominant diamagnetic phosphorus-containing de-
composition product. At the end of 2 weeks, the solution
contained both complexes 5 and 7 in an ratio of ca. 3:2. Pure
samples of complex [Cp*Ru(CO)(dppe)]BF4 could be obtained
by chromatography.
formula
fw
color and habit
cryst syst
space group
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
C116H103BCl2OP4Ru
1920.7
dark green rod
triclinic
P1h
15.431(5)
17.466(3)
19.143(3)
80.33(2)
81.03(2)
69.02(2)
4723(2)
2
1.396
0.496
1988
Z
d
calcd, g cm-3
abs coeff, mm-1
F(000)
radiation
2θ range, deg
scan type
scan speed, deg/min
scan range (ω), deg
std rflns
Mo KR (λ ) 0.071 073 Å)
Air Oxid a t ion of [Cp (P P h 3)2R u dCdCdCH CtCR u -
(P P h 3)2Cp ]BF 4. An appropriate amount of complex 6 was
dissolved in CDCl3 in an NMR tube. After 31P and 1H NMR
spectra of the solution were collected, the solution in the NMR
3.0-50
2θ-θ
variable; 5.00-60.00o in ω
1.02 plus KR separation
3 measd every 150 rflns
0 e h e 15, -19 e k e 20,
-22 e l e 22
16 347
1
tube was then exposed to air. 31P and H NMR spectra of the
sample were collected again after the solution was exposed to
air for 1 day, 2 days, 3 days, 5 days, 1 week, and 2 weeks. The
experiment showed that the intensities of the signals due to
complex 6 gradually decreased and those due to complex
[CpRu(CO)(PPh3)2]BF4 (8) and PPh3dO gradually increased.
Signals due to other uncharacterized species were also ob-
served. At the end of 2 weeks, the signals due to complex 6
almost completely disappeared and those of complex 8 and
PPh3dO became predominant. Pure samples of [CpRu(CO)-
(PPh3)2]BF4 could be obtained by chromatography.
index range
no. of rflns collected
no. of indep rflns
no. of obsd rflns
abs corr
weight scheme
no. of params refined
final R indices (obsd data), %
goodness of fit
15 688 (Rint ) 2.37%)
7491 (F > 4.0σ(F))
semiempirical
unit weight
1111
R ) 6.25, Rw ) 5.21
1.16
0.74, -1.03
largest diff peak, largest
diff hole, e Å-3
Cp *(d p p e)Ru CtCCH(CH2COMe)CtCRu (d p p e)Cp * (9).
To a solution of 5 (0.179 g, 0.126 mmol) in acetone (10 mL)
was added KOBut (28 mg, 0.25 mmol). The reaction mixture
turned yellow in 10 min and was stirred for a further 1 h at
room temperature. The solvent of the reaction mixture was
removed under vacuum, and the residue was extracted with
hexane (100 mL) to give a yellow solution. The hexane was
removed completely under vacuum to give a yellow solid.
Yield: 152 mg, 87%. Anal. Calcd for C80H84OP4Ru2: C, 69.24,
H, 6.10. Found: C, 69.65; H, 5.95. IR (KBr, cm-1): 2080 (m)
[ν(CtC)], 1704 (m) [ν(CdO)]. 1H NMR (CDCl3): δ 6.88-7.74
for an X-ray diffraction study were obtained by slow diffusion
of Et2O into a CH2Cl2 solution of [Cp(PPh3)2RudCdCd
CHCtCRu(PPh3)2Cp]BF4 containing NaBPh4 at room tem-
perature. A specimen of dimensions 0.3 × 0.3 × 0.6 mm was
mounted on
a glass fiber and used for X-ray structure
determination. The diffraction data were collected on
a
Siemens P4-RA diffractometer at 228 K. The crystal system
was triclinic, and the space group is P1h. A total of 16 347
intensity measurements were made using the 2θ-θ scan
technique in the range 3.0-50° (Mo KR radiation). Of these,
15 668 were unique (Rint ) 2.37%) and 7491 observed (F g
4σ(F)), which were used for structure solution and refinement
employing the SHELXTL PLUS program package. Solution
by direct methods yielded the positions of all non-hydrogen
atoms. Refinement by full-matrix least squares resulted in
final discrepancy indices of R ) 6.25% and Rw ) 5.21% with
GOF ) 1.16. All non-hydrogen atoms were refined with
anisotropic thermal parameters. All hydrogens, including that
on the central bridging carbon atom C(3), were revealed in
difference Fourier maps but then placed in geometrically
determined positions with dC-H ) 0.96 Å and refined isotro-
pically with riding constraints and group thermal parameters.
The data to parameter ratio was 6.7:1 and the residual electron
density 0.74 e Å-3. Further crystallographic details are given
in Table 1, and selected bond distances and angles are listed
in Table 2.
3
(m, 40 H, 8 Ph), 3.80 (t, 1 H, J (HH) ) 7.2 Hz, CtCCHCtC),
2.44-2.72 (m, 4 H, 2 CH2), 2.08 (d, 3J (HH) ) 7.2 Hz, 2 H,
CH2CdO), 1.80-2.04 (m, 4 H, 2 CH2), 1.53 (s, 3 H, COCH3),
1.49 (s, 30 H, 10 CH3). 31P{1H} NMR (CDCl3): δ 81.6 (d, J (PP)
) 11.6 Hz), 80.4 (d, J (PP) ) 11.6 Hz). 13C{1H} NMR (CDCl3):
δ 209.9 (s, CdO), 140.2-137.2 (m, ipso-Ph), 134.2-126.9 (m,
o,m,p-Ph). 106.6 (s, RuCtC), 102.1 (t, 2J (PC) ) 25.4 Hz,
RuCtC), 91.8 (s, C5Me5), 53.9 (s, CH2CdO), 29.4 (s, CH3CdO),
28.7-29.1 (m, PCH2), 22.5 (s, RuCtCCH), 10.0 (s, C5Me5).
Cp(P P h 3)2Ru CtCCH(CH2COMe)CtCRu (P P h 3)2Cp (10).
To a solution of 6 (0.193 g, 0.126 mmol) in acetone (10 mL)
was added KOBut (28 mg, 0.25 mmol). The reaction mixture
turned yellow and was stirred for 15 min at room temperature.
The solvent was removed under vacuum to give a brown solid,
and the residue was extracted with 10 mL of hexane/benzene
(2/1 v/v) to give a yellow solution. The solvents were removed
completely under vacuum to give a yellow solid. Yield: 158
mg, 84%. Anal. Calcd for C90H76OP4Ru2: C, 72.08; H, 5.11.
Found: C, 72.46; H, 5.03. IR (KBr, cm-1): 2087 (m) [ν(CtC)],
1703 (m) [ν(CdO)]. 1H NMR (CD2Cl2): δ 7.80-7.09 (m, 60 H,
12 Ph), 4.31 (s br, 11 H, 2 C5H5, CtCCHCtC, the latter proton
is buried in the Cp signal, as confirmed by a C-H COSY
experiment), 2.37 (d, J (HH) ) 6.8 Hz, 2 H, CH2), 1.71 (s, 3 H,
CH3). 31P{1H} NMR (CDCl3): δ 48.9 (s). 13C{1H} NMR (CD2-
Cl2): δ 208.1 (s, CdO), 139.7-139.0 (m, ipso-Ph), 133.8-126.7
(m, o,m,p-Ph), 112.5 (s, RuCtC), 89.5 (t, 2J (PC) ) 24.7 Hz,
RuCtC), 53.4 (s, CH2CdO), 29.9 (s, CH3CdO), 26.3 (s,
RuCtCCH).
Resu lts a n d Discu ssion
Syn th esis of C5H2- a n d C5H-Br id ged Bim eta llic
Com p lexes. As shown in Scheme 1, C5H2- and C5H-
bridged complexes can be readily prepared from the
reactions of HCtCCH(OH)CtCH with appropriate
ruthenium precursors.
Treatment of [Cp*Ru(dppe)]BF4 or [Cp*Ru(THF)-
(dppe)]BF4 (generated in situ from the reaction of
Cp*RuCl(dppe) (1) with AgBF4 in THF) with 0.45 equiv
of HCtCCH(OH)CtCH caused an immediate color
Cr yst a llogr a p h ic An a lysis of [Cp (P P h 3)2R u dCdCd
CHCtCRu (P P h 3)2Cp ]BP h 4‚CH2Cl2‚Et2O. Suitable crystals

Dimeric Ruthenium Complexes Bridged with C5H
Organometallics, Vol. 16, No. 13, 1997 2943
Ta ble 2. Selected Bon d Dista n ces a n d An gles for
[Cp (P P h 3)2Ru dCdCdCHCtCRu (P P h 3)2Cp ]-
BP h 4‚CH2Cl2‚Et2O
the CpRu(PPh3)2 moiety. Treatment of [CpRu(PPh3)2]-
BF4 or [CpRu(THF)(PPh3)2]BF4 (generated in situ from
the reaction of CpRuCl(PPh3)2 (2) with AgBF4 in THF/
CH2Cl2) with 0.45 equiv of HCtCCH(OH)CtCH led to
the formation of the analogous C5H2-bridged complex
[Cp(PPh3)2RudCdCdCHCHdCdRu(PPh3)2Cp](BF4)2 (4)
as the predominant product. Difficulty was encountered
in the attempt to obtain analytically pure compound 4
from the reaction mixture using column chromatogra-
phy, as complex 4 was readily deprotonated by alumina
or silica gel to form the C5H-bridged compound
[Cp(PPh3)2RudCdCdCHCtCRu(PPh3)2Cp]BF4 (6). In
fact, an analytically pure sample of 6 can be readily
obtained by passing the reaction mixture through a
column of neutral alumina or silica gel. Analytically
pure samples of 4 can be obtained conversely by the
quantitative reaction of HBF4‚Et2O with pure samples
of complex 6.
Bond Distances (Å)
Ru(1)-P(1)
Ru(2)-P(3)
Ru(1)-C(11)
Ru(1)-C(13)
Ru(1)-C(15)
Ru(2)-C(22)
Ru(2)-C(24)
Ru(1)-C(1)
C(1)-C(2)
2.305(3)
2.304(3)
2.253(12)
2.259(9)
2.224(10)
2.232(11)
2.267(13)
1.933(8)
1.241(12)
1.387(16)
Ru(1)-P(2)
Ru(2)-P(4)
Ru(1)-C(12)
Ru(1)-C(14)
Ru(2)-C(21)
Ru(2)-C(23)
Ru(2)-C(25)
Ru(2)-C(5)
C(2)-C(3)
2.307(3)
2.335(3)
2.259(10)
2.263(8)
2.248(13)
2.249(11)
2.260(12)
1.913(10)
1.364(11)
1.256(15)
C(3)-C(4)
C(4)-C(5)
Bond Angles (deg)
P(1)-Ru(1)-P(2)
P(2)-Ru(1)-C(1)
P(3)-Ru(2)-C(5)
Ru(1)-C(1)-C(2)
C(2)-C(3)-C(4)
C(4)-C(5)-Ru(2)
102.7(1)
90.0(3)
89.8(1)
176.6(8)
130.3(11)
176.6(8)
P(1)-Ru(1)-C(1)
P(3)-Ru(2)-P(4)
P(4)-Ru(2)-C(5)
C(1)-C(2)-C(3)
C(3)-C(4)-C(5)
85.3(3)
101.4(1)
89.8(1)
166.5(12)
167.4(10)
The C5H2-bridged compounds 3 and 4 are probably
formed via the dehydration of the hydroxyvinylidene
intermediates [(C5R5)(PR3)2RudCdCHCH(OH)CHd
CdRu(PR3)2(C5R5)](BF4)2. Although we were unable to
isolate these intermediates, it has been established that
reactions of coordinatively unsaturated complexes with
simple 1-alkynols can lead to allenylidene or vinylvi-
nylidene complexes via hydroxyvinylidene inter-
mediates.10-16,22 For example, spontaneous dehydration
of hydroxyvinylidene intermediates to give allenylidene
complexes occurred in the reactions of 1-alkynol with
electrophilic ruthenium centers such as [CpRu(PR3)2]+,11
[(η5-C9H7)Ru(PR3)2]+,13 [RuCl(dppm)2]+,12a-c and [RuCl-
(N(CH2CH2PPh2)3)]+.12e Stable ruthenium hydroxyvi-
nylidene complexes can only be isolated with more
electron rich metal centers such as [Cp*Ru(PMe2-
Ph)2]+,10 and RuCl2((i-Pr)2PCH2CO2Me)2.22b
Sch em e 1
Complexes 3-6 are moderately air-sensitive com-
pounds. Although they can be handled briefly in air in
the solid state, decomposition was observed when their
solutions were exposed to air. When solutions of
complexes 3 and 5 were exposed to air for several days
or longer, the carbonyl complex [Cp*Ru(CO)(dppe)]BF4
(7) was produced as the major decomposition product,
which was readily characterized by spectroscopic meth-
ods and by elemental analysis. In particular, the IR
spectrum showed a strong absorption at 1975 cm-1
assignable to ν(CtO) and the 13C NMR showed a CtO
resonance at 202.7 ppm (t, J (PC) ) 16.0 Hz). Exposure
of complexes 4 and 6 to air for several days or longer
led to the isolation of the known complex [CpRu(CO)-
(PPh3)2]+ (8).23 It was also noted that small amounts
of the carbonyl complexes 7 and 8 could be obtained in
the purification of the C5H-bridged complexes 5 and 6
using column chromatography. Reactions of ruthenium
vinylidene complexes with oxygen or water to give
change from orange to purple. The purple C5H2-bridged
compound [Cp*(dppe)RudCdCdCHCHdCdRu(dppe)-
Cp*](BF4)2 (3) could be isolated in good yield from the
reaction mixture using ether as the precipitating sol-
vent. Compound 3 can be easily deprotonated by
alumina or silica gel to give the C5H-bridged complex
(22) For additional examples of reactions of transition metal com-
plexes with 1-alkynols, see: (a) Zhang, L.; Gamasa, M. P.; Gimeno, J .;
Carbajo, R. J .; Lo´pez-Ortiz, F.; Lanfranchi, M.; Tiripicchio, A. Orga-
nometallics 1996, 15, 4274. (b) Werner, H.; Stark, A.; Steinert, P.;
Gru¨nwald, C.; Wolf, J . Chem. Ber. 1995, 128, 49. (c) Werner, H.;
Rappert, T.; Wiedemann, R.; Wolf, J .; Mahr, N. Organometallics 1994,
13, 2721 and references therein. (d) Nakanishi, S.; Goda, K.; Uchiyama,
S.; Otduji, Y. Bull. Chem. Soc. J pn. 1992, 65, 2560. (e) Fisher, H.; Roth,
G.; Reindl, D.; Troll, C. J . Organomet. Chem. 1993, 454, 133. (f)
O’Connor, J . M.; Hiibner, K. J . Chem. Soc., Chem. Commun. 1995,
1209. (g) Pilette, D.; Ouzzine, K.; Le Bozec, H.; Dixneuf, P. H.; Rickard,
C. E. F.; Roper, W. R. Organometallics 1992, 11, 809 and references
therein.
[Cp*(dppe)RudCdCdCHCtCRu(dppe)Cp*]BF4
(5).
Deprotonation of vinylidene complexes with alumina to
give corresponding σ-acetylide complexes has been
reported previously.16b,21
The above reactions can be applied to synthesize
C5H2- and C5H-bridged bimetallic complexes containing
(21) Hodge, A. J .; Ingham, S. L.; Kakkar, A. K.; Khan, M. S.; Lewis,
J .; Long, N. J .; Parker, D. G.; Raithby, P. R. J . Organomet. Chem. 1995,
488, 205.
(23) Blackmore, T.; Bruce, M. I.; Stone, F. G. A. J . Chem. Soc. A
1971, 2376.

2944 Organometallics, Vol. 16, No. 13, 1997
Xia et al.
Sch em e 2
The presence of the Ru2(µ-C5H) unit in complexes 5
and 6 is supported by their IR and multinuclear NMR
spectroscopic data. In the IR spectra, a strong IR band
assignable to ν(CdCdC) was observed at ca. 1881 cm-1
for both 5 and 6. The 13C NMR of complex 5 (in CDCl3)
displayed the signals for the five carbons of RudCd
CdCHCtCRu at 225.6 (t, 2J (PC) ) 20.9 Hz, C(R)), 163.1
(s, C(â)), and 128.4 ppm (s, C(γ)) ppm. The 13C signals
for the five carbons of RudCdCdCHCtCRu of complex
2
6 (in CD2Cl2) were observed at 228.5 (t, J (PC) ) 21.7
Hz, C(R)), 168.5 (s, C(â)), and 133.1 ppm (s, C(γ)). In
the 1H NMR spectrum of complex 6 (in CD2Cl2), the C5H
signal was observed as a quintet at 7.88 ppm with
5J (PH) ) 1.1 Hz. For complex 5, the C5H signal was
not readily seen in the normal 1H NMR spectrum,
presumably buried in the signals (7.05-7.48 ppm) of the
1
phenyl groups. This was confirmed by a H-13C COSY
spectrum, which indicated that the signal for the C5H
proton should appear at 7.38 ppm. The 13C data
associated with Ru2(µ-C5H) groups indicated that the
C5H-bridged complexes have a symmetric delocalized
structure with two identical ruthenium centers. Struc-
tures A-C are three of the possible resonance struc-
corresponding CO-containing complexes have been re-
ported for several cases.10,24 25
Sp ectr oscop ic Ch a r a cter iza tion of C5H2- a n d
C5H-Br id ged Bim eta llic Com p lexes. The C5H2-
bridged complexes 3 and 4 have been characterized by
IR and multinuclear NMR spectroscopy and elemental
analysis. In the 1H NMR spectrum of complex 3 (in
CDCl3), the signals for RudCdCH and RudCdCdCH
were observed at 3.90 (d, J (HH) ) 11.7 Hz) and 6.01
ppm (d, J (HH) ) 11.7 Hz), respectively. The Ru2(µ-
C5H2) assembly of complex 3 is indicated by 13C NMR
(in CDCl3), which showed resonances at 353.7 (t, J (PC)
) 15.6 Hz), 281.1 (t, J (PC) ) 19.6 Hz), 188.9 (s), 132.8
(s), and 128.1 (s) ppm for the five carbons in RudCd
CdCHCHdCdRu. The signals at 281.1, 188.9, and
132.8 ppm can be assigned to the RudCdCdCH group,9
and those at 353.7 and 128.1 ppm can be assigned to
1
the RudCdCH group.9 The H and 13C NMR assign-
ments have been confirmed by the 1H-13C COSY
spectrum. Consistent with the structure, the 31P NMR
spectrum of 3 in CDCl3 gave two singlets for the dppe
ligand at 76.9 and 67.5 ppm. IR bands assignable to
ν(CdCdCHCHdC) at ca. 1953 (s) and 1881 (m) cm-1
were also observed for 3.
The presence of the Ru2(µ-C5H2) assembly in complex
4 is indicated by 1H and 13C NMR. In the 1H NMR
spectrum of complex 4 in CD2Cl2, the signals for
RudCdCH and RudCdCdCH were observed at 8.30
(d, J (HH) ) 11.7 Hz) and 5.98 ppm (d, J (HH) ) 11.7
Hz), respectively. In the 13C NMR spectrum of complex
4 in CD2Cl2, the resonances for the five carbons of
RudCdCdCHCHdCdRu were observed at 282.4 (t,
J (PC) ) 19.2 Hz, RudCdCdCH), 191.1 (s, RudCdCd
CH), 138.0 (s, RudCdCdCH), 134.3 (s, CHdCdRu),
and 359.1 ppm (t, J (PC) ) 15.1 Hz, CHdCdRu).
Consistent with the structure, the 31P NMR spectrum
in CD2Cl2 gave two singlets for the PPh3 ligands at 46.7
and 37.6 ppm.
tures for the C5H-bridged complexes of the type
[(C5R5)(PR3)2RudCdCdCHCtCRu(PR3)2(C5R5)]+. Con-
sistent with the delocalized structure, the 1H NMR
spectra gave only one Cp* signal for 5 and one Cp signal
for 6 and the 31P NMR spectra gave only one singlet at
78.4 ppm for the dppe ligand for 5 and only one singlet
at 46.8 ppm for the PPh3 ligand for 6.
Solid -St a t e St r u ct u r e of [Cp (P P h 3)2R u dCd
CdCHCtCRu (P P h 3)2Cp ]BP h 4. To confirm the struc-
tures of complexes 5 and 6, we have attempted to grow
their crystals for X-ray diffraction study. Unfortunately,
crystals of good quality could not be obtained for 5 and
-
(24) (a) Bianchini, C.; Innocenti, P.; Peruzzini, M.; Romerosa, A.;
Zanobini, F. Organometallics 1996, 15, 272. (b) Mezzetti, A.; Consiglio,
G.; Morandini, F. J . Organomet. Chem. 1992, 430, C15. (c) Oro, L. A.;
Ciriano, M. A.; Foces-Foces, C.; Cano, F. H. J . Organomet. Chem. 1985,
289, 117. (d) Bruce, M. I.; Swincer, A. G.; Wallis, R. C. J . Organomet.
Chem. 1979, 171, C5.
6. However, by substituting the BF4 counteranion in
complex 6 with BPh4-, we have successfully obtained
good-quality crystals of [Cp(PPh3)2RudCdCdCHCtCRu-
(PPh3)2Cp]BPh4 ,which cocrystallized with ether and
CH2Cl2. A view of the molecular structure of the cation
[Cp(PPh3)2RudCdCdCHCtCRu(PPh3)2Cp]+ is shown
(25) Bianchini, C.; Casares, J . A.; Peruzzini, M.; Romerosa, A.;
Zanobini, F. J . Am. Chem. Soc. 1996, 118, 4585 and references therein.

Dimeric Ruthenium Complexes Bridged with C5H
Organometallics, Vol. 16, No. 13, 1997 2945
F igu r e 1. Molecular structure for the cation [CpRu(PPh3)2CdCdCHCdCRu(PPh3)2Cp]+.
Ta ble 3. Selected Bon d Len gth s (Å) a n d An gles (d eg) for Ru th en iu m Allen ylid en e a n d
Acetylid e Com p lexes
complex
Ru-C(R)
C(R)-C(â)
C(â)-C(γ)
Ru-C(R)-C(â)
C(R)-C(â)-C(γ)
ref
[CpRu(PPh3)2CdCdCHCtCRu(PPh3)2Cp]+
1.933(8)
1.913(8)
1.884(5)
1.878(5)
1.889(5)
1.85(2)
1.84(1)
1.921(5)
1.94(2)
2.001(3)
1.996(3)
2.017(5)
2.009(3)
1.989(7)
1.994(5)
1.99(2)
2.038(7)
2.02(1)
1.99(2)
1.241(12)
1.256(15)
1.256(8)
1.260(7)
1.256(1)
1.29(3)
1.27(2)
1.254(7)
1.24(2)
1.217(4)
1.212(5)
1.214(7)
1.204(5)
1.224(10)
1.202(8)
1.23(2)
1.172(9)
1.20(1)
1.19(2)
1.364(11)
1.387(16)
1.329(9)
1.353(7)
1.339(7)
1.39(3)
1.34(2)
1.369(7)
1.36(2)
1.370(6)
1.427(5)
1.462(8)
1.444(5)
1.430(9)
1.432(7)
1.43(3)
176.6(8)
176.6(8)
175.9(5)
168.5(5)
173.6(4)
179.0(2)
178(1)
166.5(12)
167.4(11)
175.1(7)
168.2(7)
173.2(5)
177.0(2)
175(1)
this work
[Cp(PMe3)2RudCdCdCPh2]+
[(C9H7)(PPh3)2RudCdCdCPh2]+
[(C9H7)(PPh3)2RudCdCdC(C13H20)]+
[(dppm)2ClRudCdCdC(C14H10)]+
(PO)2Cl2RudCdCdCPh2
11
13a
16b
12b
22b
12e
14
4d
4d
26
26
27
27
27
28
29
30
[(NP3)ClRudCdCdC(OMe)CHdCPh2]+
[Cp*2Cl2Ru2(µ-S-i-Pr)2dCdCdCPh2]+
[Cp(PPh3)2Ru]2(µ-C4)
174.1(3)
174(1)
170.2(6)
165(2)
178.9(2)
176.1(3)
177.7(4)
178.1(3)
177.7(6)
175.9(4)
178(2)
179.4(7)
175.1(11)
173(2)
177.2(3)
169.8(3)
170.6(5)
176.3(4)
174.5(7)
175.0(9)
177(3)
172(1)
175.2(14)
178(3)
Cp(PPh3)2RuCtCCOCH3
Cp(PPh3)2RuCtCPh
Cp(dppe)RuCtCPh
Cp(PPh3)2RuCtCC6H4-4-NO2
Cp(PMe3)2RuCtCPh
Cp(PMe3)2RuCtCC6H4-4-NO2
Cp(Ph2PCH2CHMePPh2)RuCtCPh
Cp(PPh3)2RuCtCC(O2CCF3)dCMe2
[Cp(PPh3)2RuCtCFc]PF6
1.42(2)
1.38(3)
[Cp(CO)2Ru]2(µ-CtC)
Cp(PMe3)2RuCtCZrClCp2
2.05(1)
1.989(13)
1.19(1)
1.251(2)
178.1(9)
169.9(3)
4g
5d
in Figure 1, and selected bond distances and angles are
given in Table 2. For comparison, selected structural
data for several ruthenium acetylide and allenylidene
complexes are also collected in Table 3.
The structure can be described as two three-legged
piano stools symmetrically bridged with a C5H unit. The
four PPh3 ligands are bonded to ruthenium almost
symmetrically with Ru-P bond distances in the range
2.304(3)-2.335(3) Å. The Ru-P bond distances are
within the range of those reported for related ruthenium
complexes such as CpRu(PPh3)2CtCPh26 and [CpRu-
(PPh3)2dCdCPhMe]I.26 The Ru-C(Cp) bond distances
are in the range 2.224(10)-2.267(13) Å. These values
are also similar to those reported for related Cp ruthe-
nium complexes, such as CpRu(PPh3)2CtCPh26 and
[CpRu(PPh3)2dCdCPhMe]I.26
The most interesting feature of the structure is in the
C5H moiety. The C5H unit bridges the two ruthenium
centers in a V-shape (C(2)-C(3)-C(4) ) 130.3(11)°) in
a nearly symmetric manner. The C(2)-C(3)-C(4) angle
is slightly larger than those typically observed for
carbons in a sp2 environment, probably due to the
repulsion between the π-bonding electron pairs of C(R)-
C(â). For comparison, the C-C-C angles for CdCHC
fragments were observed in the range 123.6-128.5° for
several ruthenium vinylidene complexes LnRudCdCHR
(e.g. [CpRu(PMe3)2dCdCHMe]PF6, Cp*RuCl(P(i-Pr)2-
CH2CO2Me)dCdCHCO2Me, and [Cp*Ru(PMe2Ph)2d
CdCHPh]+).10,15,16a,31-33 The RuC3H chain is not strictly
(26) Bruce, M. I.; Humphrey, M. G.; Snow, M. R.; Tiekink, E. R. T.
J . Organomet. Chem. 1986, 314, 213.
(27) Whittall, I. R.; Humphrey, M. G.; Hockless, D. C. R.; Skelton,
B. W.; White, A. H. Organometallics 1995, 14, 3970.
(28) Consiglio, G.; Morandini, F.; Sironi, A. J . Organomet. Chem.
1986, 306, C45.
(29) Lomprey, J . R.; Selegue, J . P. Organometallics 1993, 12, 616.
(30) Sato, M.; Shintate, H.; Kawata, Y.; Sekino, M.; Katada, M.;
Kawata, S. Organometallics 1994, 13, 1956.

2946 Organometallics, Vol. 16, No. 13, 1997
Xia et al.
linear with angles of Ru(1)-C(1)-C(2) ) 176.6(8)°,
C(1)-C(2)-C(3) ) 166.5(12)°, C(3)-C(4)-C(5) ) 167.4-
(10)°, and C(4)-C(5)-Ru(2) ) 176.6(8)°. These angles
are within the range of those reported for RuCtCR or
RudCdCdCRR′ complexes, as shown in Table 3.
The symmetric nature of the C5H unit indicated by
the solution NMR data is also reflected by the solid-
state structure which showed comparable Ru-C(R)
((1.933(8), 1.913((10) Å), C(R)-C(â) (1.241(12), 1.256-
(15) Å), and C(â)-C(γ) (1.364(11), 1.387(16) Å) bond
distances. The average Ru-C(R) distance of 1.923 Å is
at the upper end of those observed for ruthenium
allenylidene complexes (1.84(1)-1.94(2) Å) and is longer
than those observed for ruthenium vinylidene complexes
of the type [(C5R5)Ru(PR3)2dCdCHR]+ and [(C9H7)Ru-
(PR3)2dCdCHR]+ (in the range of 1.76-1.87 Å for 17
such complexes in the Cambridge Crystallographic
Structure Database, October 1996 Release)10,15,16a,26,29,31-39
but is considerably shorter than those observed for
ruthenium acetylide complexes of the type CpRuL2CtCR′
(1.989-2.05 Å; see Table 3). The average C(R)-C(â)
bond distance of 1.249 Å corresponds to a bond order
between 2 and 3. It is comparable to those found for
ruthenium allenylidene complexes (in the range 1.24-
1.27 Å) and is at the lower end for those observed for
the vinylidene complexes of the type [(C5R5)Ru-
(PR3)2dCdCHR]+ and [(C9H7)Ru(PR3)2dCdCHR]+ (in
the range 1.25-1.36 Å),10,15,16a,29,31-39 and at the upper
end for those typically observed for ruthenium acetylide
complexes of the type CpRuL2CtCR (1.19-1.25 Å; see
Table 3). The average C(â)-C(γ) bond distance (1.376
Å) corresponds to a bond order between 1 and 2. It is
at the upper end of the bond distances observed for
allenylidene complexes and is significantly shorter than
that expected for C(sp2)-C(sp) single bonds. For ex-
ample, C(sp)-C(sp2) bond distances were observed at
interest.2 It is relatively more difficult to prepare
complexes with Cx bridges where x is odd, and examples
of complexes bridged with C3 or C5 have only been
synthesized recently by Gladysz et. al. through multi-
step synthesis.3a,e We have attempted to convert the
easily accessible C5H-bridged complexes to C5-bridged
complexes by removing the hydrogen from the C5H unit.
In principle, C5H-bridged complexes [(C5R5)(PR3)2-
RudCdCdCHCtCRu(PR3)2(C5R5)]+ could be converted
to C5-bridged complexes [(C5R5)(PR3)2RudCdCd
CdCdCdRu(PR3)2(C5R5)]2+ by removing a H- from the
C5H unit. As Ph3CBF4 has been successfully used
previously to abstract H- in organometallic synthesis,41
we have treated the C5H-bridged complexes 5 and 6
with Ph3CBF4. Unfortunately, reactions of the C5H-
bridged complexes 5 and 6 with Ph3CBF4 in our hands
led to complicated mixtures from which the carbonyl
complexes 7 and 8 can be isolated in low yields.
In an alternative way of converting the C5H-bridged
complexes to C5-bridged complexes, the C5H-bridged
complexes 5 and 6 were treated with bases in the
presence or absence of oxidizing agents, in the hope that
the C5H unit could be deprotonated. Reactions of 5 with
KOH or KOBut in THF or CH2Cl2 led to unidentified
products. No reactions were observed when solutions
of 5 in THF or CH2Cl2 were treated with KOH. When
the blue complex 5 was treated with KOH or KOBut in
acetone, the color changed immediately to yellow and
the bimetallic complex Cp*(dppe)RuCtC-CH(CH2-
COMe)CtCRu(dppe)Cp* (9) was isolated in good yield
(see Scheme 2). Complex 9 is air-sensitive in solution
and the carbonyl complex [Cp*Ru(CO)(dppe)]BF4 was
produced when its solution was exposed to air for 1
week.
Complex 9 may be produced by the attack on complex
5 of [CH2COCH3]- generated from the reaction of CH3-
COCH3 with KOH or KOBut. It is known that nucleo-
philes can attack C(R) or C(γ) carbons of allenylidene
groups to form carbene22g or acetylide complexes.13a,42
4d
1.427(5) Å for CpRu(PPh3)2CtCCOCH3 and at 1.462-
(4) Å for CpRu(PPh3)2CtCPh.26 Thus, the solid-state
structural data support the idea that complex 6 has a
delocalized structure with contributions from the reso-
nance structures A-C.
Complex 9 was characterized by elemental analysis
and IR and 1H, 31P, and 13C NMR spectroscopy. The
presence of CtC and CdO functional groups is indi-
cated by its IR spectrum, which showed IR bands at
2080 cm-1 assignable to ν(CtC) and at 1704 cm-1
assignable to ν(CdO). The structural assignment was
confirmed by 13C NMR, which displayed resonances for
the bridging ligand at 209.9 (s, CdO), 106.6 (s, RuCtC),
102.1 (t, 2J (PC) ) 25.4 Hz, RuCtC), 53.9 (s, CH2CdO),
29.4 (s, CH3CdO), and 22.5 ppm (s, RuCtCCH), in
addition to the signals of dppe and Cp* ligands. In
support of the structure, the 1H NMR spectrum in CD2-
Cl2 showed signals at 3.80 ppm (t, 1 H, J (HH) ) 7.2
Hz) assignable to CtCCH, 2.08 ppm (d, J (HH) ) 7.2
Hz) assignable to CH2CdO, and 1.53 ppm assignable
The orientation of the C5H unit is similar to those
11
observed for [CpRu(PMe3)2dCdCdCPh2]PF6
and
[(C9H7)Ru(PPh3)2dC)CdCR2]+ (R2 d Ph2, C13H20).13a,16b
Such an orientation is expected on the basis of theoreti-
cal calculations of allenylidene complexes so that maxi-
mum π-stabilization between the metal and the C(R)
atom can be achieved.40
Rea ction s of C5H-Br id ged Com p lexes. Bimetallic
complexes with Cx bridges are of considerable current
(31) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J . Chem.
Soc., Dalton Trans. 1982, 2203.
(32) Consiglio, G.; Morandini, F.; Ciani, G. F.; Sironi, A. Organo-
metallics 1986, 5, 1976.
(33) (a) Braun, T.; Steinert, P.; Werner, H. J . Organomet. Chem.
1995, 488, 169. (b) Werner, H.; Stark, A.; Shulz, M.; Wolf, J . Organo-
metallics 1992, 11, 1126.
(34) Bruce, M. I.; Humphrey, M. G.; Koutsantonis, G. A.; Nicholson,
B. K. J . Organomet. Chem. 1985, 296, C47.
(35) Bruce, M. I.; Koutsantonis, G. A.; Liddell, M. J .; Nicholson, B.
K. J . Organomet. Chem. 1987, 320, 217.
(36) Lomprey, J . R.; Selegue, J . P. J . Am. Chem. Soc. 1992, 114,
5518.
(37) Miller, D. C.; Angelici, R. J . Organometallics 1991, 10, 79.
(38) (a) Whittall, I. R.; Cifuentes, M. P.; Costigan, M. J .; Humphrey,
M. G.; Goh, S. C.; Skelton, B. W.; White, A. H. J . Organomet. Chem.
1994, 471, 193. (b) Bruce, M. I.; Dean, C.; Dufy, D. D. N.; Humphrey,
M. G.; Koutsantonis, G. A. J . Organomet. Chem. 1985, 295, C40.
(39) Gamasa, M. P.; Gimeno, J .; Martin-Vaca, B. M.; Borge, J .;
Garcˆıa-Granda, S.; Perez-Carren˜o, E. Organometallics 1994, 13, 4045.
(40) Schilling. B. E. R.; Hoffmann, R.; Lichtenberger, D. L. J . Am.
Chem. Soc. 1977, 101, 585.
1
to CH3CdO. These H and 13C NMR assignments have
been deduced from 13C DEPT and 2D NMR experiments
(1H-1H, 1H-13C COSY, COLOC). Consistent with this
structure, the 31P NMR spectrum in CDCl3 displayed
two doublets at 81.6 and 80.4 ppm with J (PP) ) 11.6
(41) (a) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987, p 448. (b) Braterman,
P. S. Reactions of Coordinated Ligands; Plenum Press: New York,
1986; Vol. 1, p 1004.
(42) Cadierno, V.; Gamasa, M. P.; Gimeno, J .; Borge, J .; Garcˆıa-
Granda, S. J . Chem. Soc., Chem. Commun. 1994, 2495.

Dimeric Ruthenium Complexes Bridged with C5H
Organometallics, Vol. 16, No. 13, 1997 2947
Hz. The 31P NMR data indicate that the two ruthenium
centers are equivalent and that the two PPh2 groups of
the dppe ligand are magnetically inequivalent. The
inequivalence of the two PPh2 groups in complex 9 is
expected because of the presence of H, CH2COCH3, and
Cp*Ru(dppe)CtC groups at the γ-carbon atom.
Reported bimetallic complexes closely related to the
C5H2- and C5H-bridged complexes are complexes 11 and
12.16a Complex 11 is related to the C5H2-bridged
Like complex 5, the C5H-bridged complex 6 also
reacted with acetone in the presence of KOBut or KOH
to form the bimetallic complex Cp(PPh3)2RuCtCCH-
(CH2COMe)CtCRu(PPh3)2Cp (10). The spectroscopic
data for µ-CtCCH(CH2COCH3)CtC in complex 10 are
very similar to those observed for the analogous complex
9.
It is probably not surprising to observe that the C5H-
bridged complexes [(C5R5)(PR3)2RudCdCdCHCtCRu-
(PR3)2(C5R5)]+ were not deprotonated by KOH or KOBut,
as the 19-electron complexes (C5R5)(PR3)2RudCdCd
CdC)CdRu(PR3)2(C5R5) would be generated when the
C5H unit is deprotonated. To overcome this problem,
deprotonation reactions were carried out in the presence
of oxidizing agents such as Cp2FeBF4, Ph3CBF4, and
AgBF4.43 Unfortunately we have not been able to obtain
C5-bridged complexes from these reactions yet. When
the blue C5H-bridged complex 5 was treated with Cp2-
FeBF4, Ph3CBF4, or AgBF4 in the presence of KOBut or
KOH, a mixture of products was obtained, from which
[Cp*Ru(CO)(dppe)]BF4 could be isolated. As indicated
by in situ 31P NMR, a major phosphorus-containing
greenish species (possibly a C5-bridged complex) was
produced when 5 was treated with AgBF4 in the
presence of basic alumina. However, the greenish
product appears to be very unstable and decomposed
during attempts at purification or collection of 13C NMR
spectra even at -20 °C. It is noted that the C5-bridged
complex [Cp*Re(NO)(PPh3)(µ-C5)Mn(CO)2(C5Cl5)]BF4 was
reported to be extremely light-sensitive and decomposed
in hours even in the dark.3a
Electr on ic Sp ectr a of th e Bim eta llic Com p lexes.
The C5H2- and C5H-bridged complexes are intensely
colored complexes. The C5H2-bridged complex 3 has an
intense purple color with strong absorption bands at 230
(ꢀ ) 7.8 × 104 M-1 cm-1) and 528 nm (ꢀ ) 4.2 × 104
M-1 cm-1). The C5H-bridged complex 5 has an intense
blue color with strong absorption bands at 230 (ꢀ ) 8.0
× 104 M-1 cm-1) and 630 nm (ꢀ ) 5.8 × 104 M-1 cm-1).
Complex 9, which is not conjugated, only shows a strong
absorption band near 230 nm. Since complexes 3, 5,
and 9 all have a strong absorption near 230 nm, this
absorption must be associated with the electronic tran-
sitions involving Cp*Ru(dppe). The band around 528
nm for 3 could be assigned to the electronic transition
involving the RudCdCdCHCHdCdRu unit, and the
band around 630 nm for 5 could be assigned to the
electronic transition involving RudCdCdCHCtCRu.
Like complex 5, the C5H-bridged complex 6 also has an
intense blue color with strong absorption bands at 230
(ꢀ ) 6.8 × 104 M-1 cm-1) and 600 nm (ꢀ ) 7.2 × 104
M-1 cm-1).
complexes in that they all contain one RudC and one
RudCdC linkage. Complex 12 is related to the C5H-
bridged complexes in that they all contain a RuCtC and
a RudC linkage in some of the resonance structures.
Interestingly, complex 11 also has a deep red-purple
color with a strong absorption band at 498 nm (ꢀ ) 1.2
× 104 M-1 cm-1), which is similar to that of the C5H2-
bridged complex 3 (528 nm (ꢀ ) 4.2 × 104 M-1 cm-1)).
Complex 12 has a strong absorption band at 575 nm (ꢀ
) 1.9 × 104 M-1 cm-1), which is similar to those of
complexes 5 (630 nm (ꢀ ) 5.8 × 104 M-1 cm-1)) and 6
(600 nm (ꢀ ) 7.2 × 104 M-1 cm-1)). The deep purple or
blue colors observed for complexes 3-6, 11, and 12 are
undoubtedly related to the extended electron delocal-
ization in these complexes. It should be mentioned that
strong absorption bands in the visible region were also
observed for the C3-bridged complex [Cp*Re(NO)(PPh3)(µ-
C3)Mn(CO)2Cp)]+ (ꢀmax(392 nm) ) 56 000 M-1 cm-1) and
the C5-bridged complex [Cp*Re(NO)(PPh3)(µ-C5)Mn-
(CO)2(C5Cl5)]+ (ꢀmax(480 nm) ) 60 000 M-1 cm-1).3a,e
In conclusion, this study shows that conjugated C5H2-
and C5H-bridged bimetallic complexes could be easily
prepared from reactions of HCtCCH(OH)CtCH with
coordinated unsaturated d6 complexes [(η5-C5R5)Ru-
(PR3)2]+. The C5H-bridged complexes have fully conju-
gated structures, as indicated by the solution NMR and
solid-state X-ray diffraction data.
Ack n ow led gm en t. We acknowledge financial sup-
port from the Hong Kong Research Grants Council and
the Hong Kong University of Science and Technology
and thank Mr. Alvin Siu for his technical assistance.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement coefficients,
all bond lengths, all bond angles, anisotropic displacement
coefficients, and H-atom coordinates and isotropic displace-
ment coefficients for [Cp(PPh3)2RudCdCdCHCtCRu(PPh3)2-
Cp]BPh4‚CH2Cl2‚Et2O (13 pages). Ordering information is
given on any current masthead page.
(43) Connelly, N. G.; Geiger, W. E. Chem. Rev. 1996, 96, 879.
OM970051D