Intramolecular N-H?H-Ru proton-hydride interaction in ruthenium complexes with (2-(dimethylamino)ethyl)cyclopentadienyl and (3-(dimethylamino)propyl)cyclopentadienyl ligands. Hydrogenation of CO2 to formic acid via the N-H?H-Ru hydrogen-bonded complexes

Article abstract of DOI:10.1021/om980071v

Addition of 1 equiv of HBF₄ to (η⁵-C₅H₄(CH₂) _nNMe_z)RuH(dppm) (n = 2, 3) gave [(η⁵-C₅H₄(CH₂) _nNMe2H⁺)RuH(dppm)]BF₄, in which the amine function was protonated. Relaxation time T₁ measurements indicated the existence of an intramolecular N-H?H-Ru hydrogen-bonding interaction in these complexes. A spin saturation transfer study and H/D exchange experiment with [(η-C₅H₄(CH₂)₃NMe ₂H⁺)RuH(dppm)]BF₄ revealed fast exchange, probably via a dihydrogen complex intermediate, between the hydride ligand and N-H. An attempt to grow single crystals of [(η⁵-C₅H₄(CH₂) ₃NMe₂H⁺)RuH(dppm)]BPh₄ for X-ray study resulted in isolation of crystals of the complex, [(η⁵:η¹-C₅H₄(CH ₂)₃NMe₂)Ru(dppm)]-BPh₄, with the chelating (3-(dimethylamino)propyl)cyclopentadienyl ligand. Exposure of [(η⁵:η¹-C₅H₄(CH ₂)₃NMe₂)Ru(dppm)]-BF4 to 60 atm of H₂ at 60 °C gave [(η⁵-C₅H₄(CH₂) ₃-NMe₂H⁺)RuH(dppm)]BF₄ within 30 min. Reacting [(η⁵:η¹-C₅H₄(CH ₂)₃NMe₂)Ru(dppm)]BAr′₄ (Ar′ = 3,5-(CF₃)₂C₆H₃) with Ph₂SiH₂ yielded [(η⁵-C₅H₄(CH₂) ₃NM_e2H⁺)RuH(dppm)]BAr′₄; it is proposed that hydrolysis of the η²-silane intermediate by adventitious moisture in the solvent affords an η²-dihydrogen species, and heterolytic cleavage of the dihydrogen ligand by the pendant amino group gives the final product. Heating solutions of [(η⁵:η¹-C₅H₄(CH ₂)_n-NMe₂)Ru(dppm)]BF₄ under H₂/CO₂ (40 atm/40 atm) at 80 °C for 16 h gave formic acid in low yields (n = 2, TON = 6; n = 3, TON = 8). The formation of formic acid is best explained by a mechanism involving intramolecular heterolytic cleavage of the bound H₂ to generate [(η⁵-C₅H₄(CH₂) _nNMe₂H⁺)RuH(dppm)]BF₄, followed by CO₂ insertion into the Ru-H and then N-H protonation of the formato ligand. Carbon disulfide inserted into the Ru-H bond of [(η⁵-C₅H₄(CH₂) ₃NM_e2H⁺)RuH(dppm)]BF₄ to give [(η⁵-C₅H₄(CH₂) ₃NM_e2H⁺)Ru(η ¹-SCSH)-(dppm)]BF₄.

Full text of DOI:10.1021/om980071v

2768
Organometallics 1998, 17, 2768-2777
In tr a m olecu la r N-H‚‚‚H-Ru P r oton -Hyd r id e
In ter a ction in Ru th en iu m Com p lexes w ith
(2-(Dim eth yla m in o)eth yl)cyclop en ta d ien yl a n d
(3-(Dim eth yla m in o)p r op yl)cyclop en ta d ien yl Liga n d s.
Hyd r ogen a tion of CO2 to F or m ic Acid via th e
N-H‚‚‚H-Ru Hyd r ogen -Bon d ed Com p lexes
Hei Shing Chu, Chak Po Lau,* and Kwok Yin Wong
Department of Applied Biology & Chemical Technology,
The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China
Wing Tak Wong
Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, China
Received February 2, 1998
Addition of 1 equiv of HBF4 to (η5-C5H4(CH2)nNMe2)RuH(dppm) (n ) 2, 3) gave [(η5-
C5H4(CH2)nNMe2H+)RuH(dppm)]BF4, in which the amine function was protonated. Relax-
ation time T1 measurements indicated the existence of an intramolecular N-H‚‚‚H-Ru
hydrogen-bonding interaction in these complexes. A spin saturation transfer study and H/D
exchange experiment with [(η5-C5H4(CH2)3NMe2H+)RuH(dppm)]BF4 revealed fast exchange,
probably via a dihydrogen complex intermediate, between the hydride ligand and N-H.
An attempt to grow single crystals of [(η5-C5H4(CH2)3NMe2H+)RuH(dppm)]BPh4 for X-ray
study resulted in isolation of crystals of the complex, [(η5:η1-C5H4(CH2)3NMe2)Ru(dppm)]-
BPh4, with the chelating (3-(dimethylamino)propyl)cyclopentadienyl ligand. Exposure of
[(η5:η1-C5H4(CH2)3NMe2)Ru(dppm)]BF4 to 60 atm of H2 at 60 °C gave [(η5-C5H4(CH2)3-
NMe2H+)RuH(dppm)]BF4 within 30 min. Reacting [(η5:η1-C5H4(CH2)3NMe2)Ru(dppm)]BAr′4
(Ar′ ) 3,5-(CF3)2C6H3) with Ph2SiH2 yielded [(η5-C5H4(CH2)3NMe2H+)RuH(dppm)]BAr′4; it
is proposed that hydrolysis of the η2-silane intermediate by adventitious moisture in the
solvent affords an η2-dihydrogen species, and heterolytic cleavage of the dihydrogen ligand
by the pendant amino group gives the final product. Heating solutions of [(η5:η1-C5H4(CH2)n-
NMe2)Ru(dppm)]BF4 under H2/CO2 (40 atm/40 atm) at 80 °C for 16 h gave formic acid in
low yields (n ) 2, TON ) 6; n ) 3, TON ) 8). The formation of formic acid is best explained
by a mechanism involving intramolecular heterolytic cleavage of the bound H2 to generate
[(η5-C5H4(CH2)nNMe2H+)RuH(dppm)]BF4, followed by CO2 insertion into the Ru-H and then
N-H protonation of the formato ligand. Carbon disulfide inserted into the Ru-H bond of
[(η5-C5H4(CH2)3NMe2H+)RuH(dppm)]BF4 to give [(η5-C5H4(CH2)3NMe2H+)Ru(η1-SCSH)-
(dppm)]BF4.
In tr od u ction
(Ph2PCH2)2C5H3N)2m by the very weak base diethyl
ether.
One of the features of dihydrogen complexes is the
activation of the H2 ligand with respect to heterolysis.1
Intermolecular heterolytic cleavage of η2-H2 can be
achieved by a variety of bases.2 For example, [IrH(H2)-
(bq)(PPh3)2]+ (bq ) 7,8-benzoquinolinato)2a and [Re-
(CNtBu)3(PCy3)2(H2)]+ 2b can be cleaved by strong bases
alkyllithium and alkoxides, respectively, [CpRu(dmpe)-
(H2)]+ (dmpe ) 1,2-bis(dimethylphosphino)ethane),2d
[Re(CO)2(triphos)(H2)]+ (triphos ) MeC(CH2PPh2)3),2g
and [Os(NCMe)3(PiPr3)2(H2)]2+ 2h by mild base NEt3,
and the highly acidic dihydrogen complexes [Cp*Re-
(CO)(NO)(H2)]+,2j [Cp*Ru(CO)(H2)]+,2j [Os(bpy)(CO)-
(PPh3)2(H2)]2+ (bpy ) bipyridine),2k [Os(dppe)2(CH3CN)-
Intramolecular heterolytic cleavage of the H2 ligand
results from its deprotonation by the basic site on a
coligand. This reaction and its reverse (eq 1) have been
(2) (a) Crabtree, R. H.; Lavin, M. J . Chem. Soc., Chem. Commun.
1985, 794. (b) Heinekey, D. M.; Voges, M. H.; Barnhart, D. M. J . Am.
Chem. Soc. 1996, 118, 10792. (c) Bianchini, C.; Linn, K.; Masi, D.;
Peruzzini, M.; Polo, A.; Vacca, A.; Zanobini, F. Inorg. Chem. 1993, 32,
2366. (d) Chinn, M. S.; Heinekey, M. J . Am. Chem. Soc. 1990, 112,
5166. (e) Baker, M. V.; Field, L. D.; Young, D. J . J . Chem. Soc., Chem.
Commun. 1988, 546. (f) Van Der Sluys, L. S.; Miller, M. M.; Kubas, G.
J .; Caulton, K. G. J . Am. Chem. Soc. 1991, 113, 2513. (g) Bianchini,
C.; Marchi, A.; Rossi, R.; Vacca, A. Organometallics 1995, 14, 3203.
(h) Smith, K. T.; Tilset, M.; Kuhlman, R.; Caulton, K. G. J . Am. Chem.
Soc. 1995, 117, 9473. (i) Mudalige, D. C.; Rettig, S. J .; J ames, B. R.;
Cullen, W. R. J . Chem. Soc., Chem. Commun. 1993, 830. (j) Chinn, M.
S.; Heinekey, D. M.; Payne, N. G.; Sofield, C. D. Organometallics 1989,
8, 1824. (k) Heinekey, D. M.; Luther, T. A. Inorg. Chem. 1996, 35, 4396.
(l) Schlaf, M.; Lough, A. J .; Maltby, P. A.; Morris, R. H. Organometallics
1996, 15, 2270. (m) J ia, G.; Lee, H. M.; Williams, I. D.; Lau, C. P.;
Chen, Y.-Z. Organometallics 1997, 16, 3941.
(H2)]2+ 2l and [RuCl(CO)(PMP)(H2)]+ (PMP ) 2,6-
,
(1) (a) Heinekey, D. M.; Oldham, W. J ., J r. Chem. Rev. 1993, 93,
913. (b) J essop, P. G.; Morris, R. H. Coord. Chem. Rev. 1992, 121, 155.
S0276-7333(98)00071-5 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 06/05/1998

Proton-Hydride Interaction in Ru Complexes
Organometallics, Vol. 17, No. 13, 1998 2769
Sch em e 1a
postulated to explain the H/D exchange reactions in
[IrH(H2O)(bq)(PCy3)2]+ (bq ) 7,8-benzoquinolinato),3
[Ir(H)2(HS(CH2)3SH)(PCy3)2]+,4 and [IrH(X)(NH3)2-
(PEt3)2]:+,2+ (X ) Cl-, NH3, PEt3).5 Intramolecular
proton transfer from the bound H2 to, or σ-metathesis
of H2 ligand with, the neighboring organic group could
be important in mechanisms of hydrogenation,6 hydro-
genolysis,7 hydroformylation,8 CO2 reduction,9 and hy-
drogenase reactions.10 Recently, Crabtree’s group11 and
that of Morris12 have independently discovered com-
plexes containing intramolecular H‚‚‚H interactions of
the type O-H‚‚‚H-Ir and N-H‚‚‚H-Ir. These com-
pounds are regarded as intermediates in the intramo-
lecular heterolytic splitting of dihydrogen. A dihydro-
gen complex, [Os(H2)(CO)(quS)(PPh3)2]+ (quS ) quino-
line-8-thiolate), was found to be in equilibrium with its
coordinated thiol tautomer [Os(H)(CO)(quSH)(PPh3)2]+.13
We report here the synthesis and characterization of
two ruthenium complexes containing intramolecular
N-H‚‚‚H-Ru interactions and demonstrate that exist-
ence of the equilibrium shown in eq 1 may account for
the chemical properties of these complexes.
a
t
Legend: (i) RuCl3, PPh3, refluxed in EtOH; (ii) BuOK,
stirred in THF; (iii) Ru(PPh3)3Cl2, stirred in THF; (iv) dppm,
refluxed in toluene; (v) MeONa, refluxed in MeOH.
Resu lts a n d Discu ssion
that of the reaction for preparation of the Cp analogue
(η5-C5H5)RuCl(PPh3)2 (90-95%).14 The low yield was
probably due to formation of an unidentified greenish
brown side product. The amine group in the sidearm
of 1‚HCl was protonated; protonation of nitrogen was
confirmed by the downfield shift of the protons of the
Syn t h esis a n d Ch a r a ct er iza t ion of (η5-C5H 4-
(CH2)n NMe2)R u H (d p p m ) (n ) 2, 3) a n d R ela t ed
Com plexes. The dppm hydride complex (η5-C5H4(CH2)2-
NMe2)RuH(dppm) (5) was prepared according to the
sequence in route A of Scheme 1. Treatment of a
refluxing ethanol solution of triphenylphosphine with
a RuCl3‚xH2O/C5H5(CH2)2NMe2 solution (in ethanol)
gave (η5-C5H4(CH2)2NMe2H+Cl-)RuCl(PPh3)2 (1‚HCl).
The yield of this reaction was low (37%) compared to
1
methyl groups attached to it. The H NMR spectrum
of 1‚HCl showed the N-methyl protons at 2.86 ppm,
while those of the free ligand C5H5(CH2)2NMe2 were
measured at 2.27 ppm. Similar downfield shifts of the
N-methyl protons have been observed in the titanium,15
molydenum,16 rhenium,17 and rhodium18 complexes
containing similar ligands. Protonation of the amine
group in 1‚HCl was also supported by observation of
the broad singlet signal of N-H at 12.30 ppm in the
1H NMR spectrum. Furthermore, the IR spectrum of
1‚HCl showed a broad band in the 2400-2700 cm-1
region, indicating nitrogen protonation. The 31P{1H}
NMR spectrum of 1‚HCl showed a single resonance,
consistent with the chemical equivalence of the two
triphenylphosphine ligands. Substitution of PPh3 ligands
in 1‚HCl with dppm produced the dppm chloro complex
(η5-C5H4(CH2)2NMe2H+Cl-)RuCl(dppm) (3‚HCl). Its 1H
NMR spectrum showed the N-H signal at 11.95 ppm,
and the N-methyl proton signal (2.62 ppm) was down-
field relative to that of the free ligand. The IR spectrum
(3) Crabtree, R. H.; Lavin, M.; Bonneviot, L. J . Am. Chem. Soc. 1986,
108, 4032.
(4) J essop, P. G.; Morris, R. H. Inorg. Chem. 1993, 32, 2236.
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elas, M. A.; Oro, L. A. Organometallics 1992, 11, 138. (b) Andriollo,
A.; Esteruelas, M. A.; Meyer, U.; Oro, L. A.; Sanchez, D. R. A.; Sola,
E.; Valero, C.; Werner, H. J . Am. Chem. Soc. 1989, 111, 7431. (c) Chan,
W. C.; Lau, C. P.; Chen, Y. Z.; Fang, Y. Q.; Ng, S. M.; J ia, G.
Organometallics 1997, 16, 34.
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309, 65. (b) Guo, Z. Y.; Bradley, P. K.; J ordan, R. F. Organometallics
1992, 11, 2690. (c) Albeniz, A. C.; Schulte, G.; Crabtree, R. H.
Organometallics 1992, 11, 242. (d) Lee, J . C., J r.; Peris, E.; Rheingold,
A. L.; Crabtree, R. H. J . Am. Chem. Soc. 1994, 116, 11014.
(8) Versluis, L.; Ziegler, T. Organometallics 1990, 9, 1985.
(9) Hutschka, F.; Dedieu, A.; Leitner, W. Angew. Chem., Int. Ed.
Engl. 1995, 34, 1742.
(10) (a) Zimmer, M.; Schulte, G.; Luo, X.-L.; Crabtree, R. H. Angew.
Chem., Int. Ed. Engl. 1991, 30, 193. (b) Sellmann, D.; Ka¨ppler, J .; Moll,
M. J . Am. Chem. Soc. 1993, 115, 1830.
(11) (a) Crabtree, R. H.; Siegbahn, P. E. M.; Eisenstein, O.; Rhein-
gold, A. L.; Koetzle, T. Acc. Chem. Res. 1996, 29, 348. (b) Yao, W.;
Crabtree, R. H. Inorg. Chem. 1996, 35, 3007. (c) Peris, E.; Lee, J . C.,
J r.; Rambo, J . R.; Eisenstein, O.; Crabtree, R. H. J . Am. Chem. Soc.
1995, 117, 3485. (d) Lee, J . C., J r.; Rheingold, A. L.; Muller, B.;
Pregosin, P. S.; Crabtree, R. H. J . Chem. Soc., Chem. Commun. 1994,
1021.
(14) Bruce, M. I.; Hameister, C.; Swincer, A. G.; Wallis, R. C. Inorg.
Synth. 1982, 21, 78.
(15) (a) Flores, J . C.; Chien, J . C. W.; Rausch, M. D. Organometallics
1994, 13, 4140. (b) van der Zeijden, A. A. H. J . Organomet. Chem. 1996,
518, 147.
(12) (a) Xu, W.; Lough, A. J .; Morris, R. H. Inorg. Chem. 1996, 35,
1549. (b) Park, S.; Lough, A. J .; Morris, R. H. Inorg. Chem. 1996, 35,
3001. (c) Lough, A. J .; Park, S.; Ramachandran, R.; Morris, R. H. J .
Am. Chem. Soc. 1994, 116, 8356. (c) Park, S.; Ramachandran, R.;
Lough, A. J .; Morris, R. H. J . Chem. Soc., Chem. Commun. 1994, 2201.
(13) Schlaf, M.; Morris, R. H. J . Chem. Soc., Chem. Commun. 1995,
625.
(16) (a) Wang, T.-F.; Lee, T.-Y.; Chou, J .-W.; Ong, C.-W. J . Orga-
nomet. Chem. 1992, 423, 31. (b) Wang, T.-F.; Wen, Y.-S. J . Organomet.
Chem. 1992, 439, 155.
(17) Wang, T.-F.; Lai, C.-Y.; Wen, Y.-S. J . Organomet. Chem. 1996,
523, 187.
(18) Philippopoulos, A.; Hadjiliadis, N.; Hart, C. E.; Donnadieu, B.;
McGowan, P. C.; Poilblanc, R. Inorg. Chem. 1997, 36, 1842.

2770 Organometallics, Vol. 17, No. 13, 1998
Chu et al.
showed the broad band of N-H at 2680 cm-1. Taken
together, it can be concluded that the amine group in
3‚HCl remained protonated. The 31P{1H} NMR spec-
trum showed a singlet at δ 15.5 ppm for the dppm ligand
of 3‚HCl. The dppm hydride complex (η5-C5H4(CH2)2-
NMe2)RuH(dppm) (5) was prepared by heating the
chloro complex 3‚HCl in refluxing methanol containing
sodium methoxide. The same route provided an excel-
lent synthesis of η5-Cp iron, ruthenium, and osmium
hydride complexes from their chloro precursors.19,20 The
1H NMR spectrum of 5 showed the hydride signal at
-11.33 ppm as a triplet of doublets (2J (HP) ) 31.5 Hz,
J (HH) ) 3.4 Hz). The hydride is coupled to two equiva-
lent phosphorus atoms and one of the methylene protons
of dppm. Coupling of the hydride ligand with one of
the methylene protons of dppm has also been observed
in Cp*RuH(dppm).20 The phosphorus atoms of the
dppm ligand in 5 appeared as a singlet at δ 22.7 ppm
in the 31P{1H} NMR spectrum. The IR spectrum of 5
of 5H+ and 6H+ revealed downfield shifts for the methyl
groups attached to nitrogen (5H+, δ 2.56 ppm; 6H+, δ
2.82 ppm) compared to the analogous resonances for the
1
free ligands. Observation of the N-H peaks in H NMR
spectra of 5H+ (δ ∼3.7 ppm, partially obscured by
neighboring peaks)) and 6H+ (δ 5.48 ppm) lends further
support to amine group protonation.
At room temperature, the hydride signal of 5H+,
which appears as a broad triplet (J (HP) ) 30.6 Hz) at
δ -11.47 ppm in the 1H NMR spectrum, is slightly
upfield (by 140 ppb) relative to the hydride signal of 5.
Unlike 5, coupling of the hydride ligand in 5H+ to the
methylene proton of the dppm ligand is not observed.
At lower temperature (-35 °C or lower), the hydride
signal of 5H+ sharpens slightly, but the H-H coupling
is still undetectable. The hydride signal of 6H+ behaves
similarly, showing a broad triplet (J (HP) ) 30.8 Hz) at
δ -11.30 ppm, which is 170 ppb upfield relative to the
hydride signal of 6; again, no H-H coupling to the dppm
methylene proton is observed. Broadening of the hy-
dride signals of 5H+ and 6H+ is probably due to H‚‚‚H
interaction between the hydride ligands and N-H on
the pendant amine arms. Broadening and upfield shift
of the hydride signal of WH(CO)2(NO)(PMe3)2 were
observed in the presence of acidic alcohol, due to the
formation of intermolecular M-H‚‚‚H-OR hydrogen
bonding.21 A slight upfield shift and significant broad-
ening of hydride signals of both cis and trans isomers
of RuH2(dppm)2 were also observed upon addition of
exesss phenol.22 The presence of an H‚‚‚H interaction
in 5H+ and 6H+ is supported by relaxation time T1 and
spin saturation transfer measurements. The relaxation
time T1 for the hydride signal of 6 was measured in
THF-d8 at room temperature and was found to be 884
ms. Upon addition of 1 equiv of HBF4•Et2O, 6 was con-
verted to 6H+, and the T1 value for the hydride signal
of the latter was found to be 642 ms, which was appre-
ciably lower than that of the hydride signal of the
former. When the same experiment was performed in
chlorobenzene-d5 instead of THF-d8, the T1 value dropped
from 966 ms for 6 to 518 ms for 6H+. Lowering of the
T1 values in the above experiments suggests some de-
gree of hydrogen-bonding interaction between the hy-
dride ligand and the N-bound proton in complex 6H+.
A significant lowering of relaxation time T1 for one of
the hydride ligands in trans-[RuH2(dppm)2] was re-
corded in the presence of PhOH at room temperature,
due to the existence of hydrogen-bonded species (dppm)2-
HRu-H‚‚‚H-OR; a dynamic equilibrium between
(dppm)2HRu-H‚‚‚H-OR and [(dppm)2HRu(H2)]+(OR)-
was established at lower temperature.22 A smaller drop
of the T1 value in THF-d8 solution can be attributed to
the presence of hydrogen-bonding interaction between
the THF-d8 molecule and the amine proton in 6H+. This
N-H‚‚‚THF hydrogen-bonding interaction is main-
tained at the expense of the N-H‚‚‚H-Ru interaction.
“Switching on and off” of intramolecular H‚‚‚H interac-
tion by using solvents of different hydrogen-bonding
abilities has been reported.12c
showed the Ru-H stretching frequency at 1916 cm-1
.
It is noted that the amine group in the sidearm of 5
has been deprotonated. Deprotonation in 5 is supported
by the fact that the chemical shift of its N-methyl pro-
tons bears strong resemblance to that of the N-methyl
protons of the free Cp-N ligand and that the broad band
in the region of 2400-2700 cm-1, indicative of nitrogen
protonation, is absent in its IR spectrum.
Complex 5 could also be prepared by following the se-
quence in route B of Scheme 1. Complexes 1 and 3 in
this route are the nonprotonated forms of 1‚HCl and
3‚HCl, respectively. Unlike those of 1‚HCl and 3‚HCl,
1
the H NMR spectra of 1 and 3 do not show downfield
shifts of the N-methyl protons in their Cp-N ligands.
The overall yield of 5 by route B is higher than that by
route A, because the formation of 1 in the former is near-
quantitative, but the yield of 1‚HCl in route A is only
37%.
Similarly, 6 was prepared according to the sequence
in route B. The hydride signal of 6 was observed at
1
-11.26 ppm in H NMR spectroscopy, also as a triplet
of doublets (J (HP) ) 30.8 Hz, J (HH) ) 3.4 Hz). The
31P{1H} NMR spectrum of 6 showed a singlet for the
phosphorus atom of dppm at δ 23.0 ppm. The Ru-H
stretching appeared as a medium to strong peak at 1929
cm-1 in the IR spectrum of 6.
Acid ifica tion of (η5-C5H4(CH2)2NMe2)Ru H(d p p m )
(5) a n d (η5-C5H4(CH2)3NMe2)Ru H(d p p m ) (6). Ad-
dition of 1 equiv of HBF4•Et2O to 5 and 6 resulted in
protonation of the pendant amine groups to give [(η5-
C5H4(CH2)2NMe2H+)RuH(dppm)]BF4 (5H+) and [(η5-
C5H4(CH2)3NMe2H+)RuH(dppm)]BF4 (6H +), respec-
tively (eq 2). Similar to those of the chloro complexes
(20) (a) J ia, G.; Morris, R. H. J . Am. Chem. Soc. 1991, 113, 875. (b)
J ia, G.; Lough, A. J .; Morris, R. H. Orgaometallics 1992, 11, 161.
(21) Shubina, E. S.; Belkova, N. V.; Krylov, A. N.; Vorontsov, E. V.;
Epstein, L. M.; Gusev, D. G.; Niedermann, M.; Berke, H. J . Am. Chem.
Soc. 1996, 118, 1105.
(22) Ayllo´n, J . A.; Gervaux, C.; Sabo-Etienne, S.; Chaudret, B.
Organometallics 1997, 16, 2000.
1
1‚HCl and 3‚HCl, room-temperature H NMR spectra
(19) (a) Bruce, M. I.; Humphrey, M. G.; Swincer, A. G.; Wallis, R.
C. Aust. J . Chem. 1984, 37, 1747. (b) Chinn, M. S.; Heinekey, D. M. J .
Am. Chem. Soc. 1990, 112, 5166.

Proton-Hydride Interaction in Ru Complexes
Organometallics, Vol. 17, No. 13, 1998 2771
Sch em e 2
Sch em e 3
Similarly, T1 values of the hydride ligand decreased
substantially when 5 was protonated with 1 equiv of
HBF4‚Et2O to form 5H+: T1 values of 5 in THF-d8 and
chlorobenzene-d5 were 1003 and 926 ms, respectively,
and those of 5H+ in THF-d8 and chlorobenzene-d5 were
found to be 243 and 188 ms, respectively. Unlike the
case for 6 f 6H+ conversion, the drops of T1 values in
the 5 f 5H+ conversion in the two solvents are
comparable; it is probably due to the fact that the
N-H‚‚‚H-Ru interaction is stronger in the latter case,
so that the N-H‚‚‚THF hydrogen-bonding interaction
only occurs to a lesser extent. Stronger N-H‚‚‚H-Ru
interaction in 5H+ than in 6H+ is also reflected by the
much smaller T1 values (in THF-d8 and chlorobenzene-
d5) of the hydride signal of the former.
ppm. That this triplet is attributable to the trans-
dihydride tautomer is based on its J (HP) value, which
is very similar to that of the Cp* dihydride complex
trans-[Cp*RuH2(dppm)]+ (J (HP) ) 28.8 Hz).20 We have
recently reported that the J (HP) value for trans-CpOsH2-
(dppm) is 31.8 Hz; the cis isomer, cis-CpOsH2(dppm),
has a much smaller J (HP) value of 6.5 Hz.23 Acidifica-
tion of 5 with slightly over 2 equiv of DBF4 (prepared
by adding 0.1 mL of D2O to 0.4 mL of 54% HBF4‚Et2O)
gave the η2-HD isotopomer [(η5-C5H4(CH2)2NMe2D+)Ru-
(HD)(dppm)](BF4)2 (7-d 2), in which both the pendant
amine function and the ruthenium hydride were deu-
terated. Its 1H NMR spectrum shows a 1:1:1 triplet
(1J (HD) ) 20.6 Hz) centered at δ -6.85 ppm, after the
η2-H2 peak is nulled using the inversion-recovery method.
The dihydrogen complex [(η5-C5H4(CH2)3NMe2H+)Ru-
(H2)(dppm)](BF4)2 (8) can be generated in a similar
manner (Scheme 3). The η2-H2 signal of 8 appears as a
To further confirm the presence of a hydride-proton
interaction in (η5-C5H4(CH2)nNMe2H+)RuH(dppm), a
spin saturation transfer experiment was carried out
with the complex 6H+. It was observed that irridation
of the hydride peak at δ -11.47 ppm led to an ap-
proximately 80% decrease in intensity of the N-H
1
broad singlet at δ -6.72 ppm in the H NMR spectrum.
1
signal at δ 5.48 ppm in H NMR. This observation can
Like 7, a trace amount of trans-dihydride tautomer is
also present. A variable-temperature T1 measurement
on the η2-H2 signal gave T1(min) of 20 ms at 255 K and
be interpreted as resulting from a rapid exchange
process between the metal hydride and the N-bonded
proton via a η2-H2 complex intermediate (Scheme 2).
Unfortunately, it is difficult to study spin saturation
transfer on 5H+ because the N-H signal is partially
obscured by the other proton signals of the complex. The
exchange process depicted in Scheme 2 was further
supported by an H/D exchange reaction of 6H+ with
D2O. We found that the metal-hydride and N-H
signals of 6H+ disappeared within 15 min after addition
of D2O to a THF-d8 solution of the complex. It is
believed that N-H first underwent H/D exchange with
D2O to give the N-D function, which then H/D-
exchanged with the metal hydride. In contrast, the
hydride ligand and the proton on the pyridinium ring
in [IrH(η1-SC5H4NH)(η2-SC5H4N)(PPh3)2]BF4 do not
seem to undergo any significant exchange, although the
presence of an Ir-H‚‚‚H-N interaction has been
ascertained.12b
1
400 MHz. The H NMR spectrum of the η2-HD isoto-
pomer [(η5-C5H4(CH2)3NMe2D+)Ru(HD)(dppm)](BF4)2
(8-d 2) shows a 1:1:1 triplet (1J (HD) ) 21.5 Hz) at -6.69
ppm, after the η2-H2 peak is nulled using the inversion-
recovery method.
X-r a y St r u ct u r e of [(η5:η1-C5H 4(CH2)3NMe2)R u -
(d p p m )]+. In an attempt to grow single crystals of
[(η5-C5H4(CH2)3NMe2H+)RuH(dppm)]BPh4 for X-ray crys-
tallographic study, single crystals of [(η5:η1-C5H4(CH2)3-
NMe2)Ru(dppm)]BPh4 (10c), which was formed by the
extrusion of a H2 molecule from [(η5-C5H4(CH2)3NMe2H+)-
RuH(dppm)]BPh4, were obtained instead. Figure 1
shows the molecular structure of the cation [(η5:η1-
C5H4(CH2)3NMe2)Ru(dppm)]+. The crystallographic de-
tails and selected bond distances and angles are given
in Tables 1 and 2, respectively.
The cation of 10c exhibits a three-legged piano-stool
geometry. The Cp ring is essentially planar, with C-C
bonds in the range 1.404(6)-1.440(6) Å. The Ru-C
distances range from 2.187(3) to 2.259(4) Å. The two
bond distances Ru-P(1) (2.3305(8) Å) and Ru-P(2)
(2.3310(8) Å) are essentially equivalent. These Ru-P
distances are similar to those in [CpRu(η2-dppm)(η1-
Addition of 1 equiv of HBF4 to 5H+ or addition of 2
equiv of HBF4 to 5 led to the formation of the dihydrogen
complex [(η5-C5H4(CH2)2NMe2H+)]Ru(H2)(dppm)](BF4)2
1
(7) (Scheme 3). The H NMR spectrum of 7 showed a
broad singlet, integrated to two hydrogens, at δ -6.82
ppm, assignable to Ru(H2). A variable-temperature T1
measurement on the η2-H2 signal gave a minimun T1
value of 20 ms (268 K and 400 MHz). A trace amount
of trans-dihydride tautomer is also present, as evidenced
by a very small triplet (J (HP) ) 29.6 Hz) at δ -5.94
dppm)]PF6 and [Cp*Ru(η2-H2)(dppm)]BF4.20,25 The
24
(23) J ia, G.; Ng, W. S.; Yao, J .; Lau, C. P.; Chen, Y. Organometallics
1996, 15, 5039.

2772 Organometallics, Vol. 17, No. 13, 1998
Chu et al.
CHMeCH2PPh2),27 85.1(1)° in CpRu((E)-MeO2CCd
CHCO2Me)(dppe),28 and 83.33(7)° in Fe(CH2C6H4Me)2-
(dippe) (dippe ) 1,2-bis(diisopropylphosphino)ethane)29)
or monodentate phosphine ligands (for example, 93.7-
(1)° in CpRu(η2-CH2dCHCHdCH2)(PMe3)2,30 103.9(4)°
in CpRuCl(PPh3)2,31 94.7(2)° in CpRuCl(PMe3)2,31 and
95.8(1)° in CpRuH(PMe3)232). However, it is comparable
with the P-Ru-P angles in other cyclopentadienyl
dppm complexes such as [CpRu(η2-dppm)(η1-dppm)]PF6
(70.0(1)°),24 [Cp*Ru(η2-H2)(dppm)]BF4 (71.46 (7)°),20,25
and CpFePh(dppm) (73.8 (1)°).33 The P(1)-C(11)-P(2)
angle (94.4 (2)°) is comparable with the correponding
angles of the η2-dppm ligands in [CpRu(η2-dppm)(η1-
24
dppm)]PF6 and [Cp*Ru(η2-H2)(dppm)]BF4.20,25 The
amine group is bent away from the two phosphorus
atoms of dppm with P(1)-Ru-N(1) and P(2)-Ru-N(1)
angles of 97.19(8) and 98.77(8)°, respectively.
Reactivities of [(η5:η1-C5H4(CH2)3NMe2)Ru (dppm )]-
BF 4 (10a ) tow a r d H2. The complex [(η5:η1-C5H4(CH2)3-
NMe2)Ru(dppm)]BF4 (10a ) was prepared in quantitative
yield by removal of the chloro ligand of (η5-C5H4(CH2)3-
NMe2)RuCl(dppm) with NaBF4 in methanol. Heating
a C6H5Cl solution of [(η5-C5H4(CH2)3NMe2H+)RuH-
(dppm)]BF4 (6H+) at 90 °C for a prolonged period of time
also led to the formation of 10a . Obviously, 10a is
produced by extrusion of H2 from 6H+. Single crystals
of 10c were grown from the solution of [(η5-C5H4(CH2)3-
NMe2H+)RuH(dppm)]BPh4 after extrusion of H2 from
the latter. We are interested in studying the reversed
reaction of the H2 extrusion from 6H+, since the
feasibility of this reaction provides strong evidence of
intramolecular heterolytic cleavage of η2-H2 ligand by
the amino sidearm of the Cp-N ligand. We therefore
monitored the reaction of 10a with H2 under 60 atm in
a high-pressure NMR tube by 1H and 31P{1H} NMR
spectroscopy. It was found that 10a was completely
converted to 6H+ within 30 min at 60 °C. Probably, 10a
first reacted with H2 to form an η2-H2 complex inter-
mediate which was then deprotonated by the pendant
amino group to form 6H+ (eq 3). It has been reported
F igu r e 1. Molecular structure of the cation [(η5:η1-
C5H4(CH2)3NMe2)Ru(dppm)]+.
Ta ble 1. Cr ysta l Da ta a n d Refin em en t Deta ils for
[(η5:η1-C5H4(CH2)3NMe2)Ru (d p p m )]BP h 4f
formula
fw
C59H58BNP2Ru
954.94
color and habit
cryst dimens, mm
cryst syst
space group
a, Å
orange block
0.19 × 0.19 × 0.29
monoclinic
P21 (No. 4)
11.170(1)
20.690(1)
11.268(1)
109.99(1)
2447.2(4)
2
b, Å
c, Å
â, deg
V, Å3
Z
D
calc, g cm-1
1.296
F(000)
996
radiation
T, °C
Mo KR (λ ) 0.710 73 Å)
25.0
diffractometer
Marresearch Image
Plate Scanner
51.3
2θmax, deg
scan type
no. of rflns collected
no of unique rflns
no. of obd rflns
ω
16 719
4410
4223 (I > 3.00 σ(I))
not applied
571
R ) 2.4, Rw ) 3.0
1.20
abs cor
no. of params refined
final R indices (obsd data), %
goodness of fit
rfln/param ratio
7.40
0.33
-0.68
max peak in final diff map, e Å-3
min peak in final diff map, e Å-3
Ru-N distance (2.238(3) Å) falls in the range of Ru-N
distances found in the complexes Cp*Ru(κ2(P,N)-Ph2-
PCH2CH2NMe2)Cl (2.260(2) Å),26 Cp*Ru(κ2-(P,N)-Ph2-
PCH2CH2NMe2)(η1-OSO2CF3) (2.256(2) Å),26 and [Cp*Ru-
(κ2-(P,N)-Ph2PCH2CH2NMe2)(CdCdCHPh)]+ (2.217(10)
Å).26 The P(1)-Ru-P(2) angle (70.81(3) Å) is smaller
than the corresponding angles reported for the three-
legged piano-stool complexes with larger chelating
diphosphine (for example, 82.9(1)° in CpRuCl(Ph2-
that the ruthenium amide complex RuCl(PPh3)[N(SiMe2
(27) Morandini, F.; Consiglio, G.; Straub, B.; Ciani, G.; Sironi, A. J .
Chem. Soc., Dalton Trans. 1983, 2293.
(28) Bruce, M. I.; Catlow, A.; Humphrey, M. G.; Kontsantonis, G.
A.; Snow, M. R.; Tiekink, E. R. T. J . Organomet. Chem. 1988, 338, 59.
(29) Hermes, A. R.; Girolami, G. S. Organometallics 1987, 6, 763.
(30) Bruce, M. I.; Hambley, T. W.; Rodgers, J . R.; Snow, M. R.; Wong,
F. S. Aust. J . Chem. 1982, 35, 1323.
(24) Bruce, M. I.; Cifuentes, M. P.; Grundy, K. R.; Liddell, M. J .;
Snow, M. R.; Tiekink, E. R. T. Aust. J . Chem. 1988, 41, 597.
(25) Klooster, W. T.; Koetzle, T. F.; J ia, G.; Fong, T. P.; Morris, R.
H.; Albinati, A. J . Am. Chem. Soc. 1994, 116, 7677.
(26) Mauthner, K.; Slugovc, C.; Mereiter, K.; Schmid, R.; Kirchner,
K. Organometallics 1997, 16, 1956.
(31) Bruce, M. I.; Wong, F. S.; Skelton, B. W.; White, A. H. J . Chem.
Soc., Dalton Trans. 1981, 1398.
(32) Brammer, L.; Klooster, W. T.; Lemke, F. R. Organometallics
1996, 15, 1721.
(33) Scott, F.; Kruger, G. J .; Cronje, S.; Lombard, A.; Raubenheimer,
H. G.; Benn, R.; Rufin´ska, A. Organometallics 1990, 9, 1071.

Proton-Hydride Interaction in Ru Complexes
Organometallics, Vol. 17, No. 13, 1998 2773
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles
(turnover number) ) 6). The same reaction had also
been monitored by high-pressure 31P{1H} NMR spec-
troscopy, which showed that 9 was completely converted
to 5H+ within 30 min, and the latter remained the only
detectable metal complex in the system after heating
for 24 h. Analogously, reaction of 10a with H2/CO2 also
gave formic acid (TON ) 8); a high-pressure 31P{1H}
NMR study of the same reaction showed that 6H+ was
the only detectable metal-containing species throughout
the experiment. It is generally true that metal com-
plexes which effect CO2 hydrogenation to formic acid
effect the reverse reaction as well. To see whether this
is true for complexes 9 and 10a , their reactions with
formic acid were studied. It was found that reactions
of 9 and 10a with formic acid in refluxing THF for 16 h
led to quantitative yields of 5H+ and 6H+, respectively.
Probably, HCOOH was first added across the Ru-N
bond to form the transient metal formate [(η5-C5H4(CH2)n-
NMe2H+)Ru(HCOO)(dppm)]BF4, which then extruded
a CO2 molecule to give 5H+ or 6H+ (eq 4).
(d eg) for [(η5:η1-C5H4(CH2)3NMe2)Ru (d p p m )]BP h 4
Interatomic Distance (Å)
Ru-C(1) 2.243(3)
Ru-C(4) 2.226(3)
Ru-C(2) 2.188(3)
Ru-C(3) 2.187(3)
Ru-C(5) 2.259(4)
Ru-N
2.238(3)
Ru-P(1) 2.3305(8) Ru-P(2) 2.3310(8)
Intramolecular Angles (deg)
P(1)-Ru-P(2)
70.81(3)
98.77(8)
96.4(1)
111.9(2)
110.9(2)
108.1(3)
P(1)-Ru-N(1)
97.19(8)
94.4(2)
96.4(1)
114.4(2)
106.0(3)
105.1(3)
P(2)-Ru-N(1)
Ru-P(1)-C(11)
Ru-N(1)-C(8)
Ru-N(1)-C(10)
C(8)-N(1)-C(10)
P(1)-C(11)-P(2)
Ru-P(2)-C(11)
Ru-N(1)-C(9)
C(8)-N(1)-C(9)
C(9)-N(1)-C(10)
Sch em e 4
CH2PPh2)2] cleaved H2 heterolytically to form two
isomeric amine-hydride derivatives of the formula
RuHCl(PPh3)[NH(SiMe2CH2PPh2)2], but the mechanism
of this reaction is not clear.34
Rea ctivity of [(η5:η1-C5H4(CH2)3NMe2)Ru (d p p m )]-
BAr ′4 (Ar ′ ) 3,5-(CF 3)2C6H3) (10b) tow a r d P h 2SiH2.
We thought it would be interesting to study the reaction
of [(η5:η1-C5H4(CH2)3NMe2)Ru(dppm)]+ with silane as
well. It was found that the reaction of 10b with Ph2-
SiH2 led to the formation of [(η5-C5H4(CH2)3NMe2H+)-
RuH(dppm)]BAr′4; the reaction sequence depicted in
Scheme 4 is postulated to explain the reaction. We
propose that Ph2SiH2 first reacted with 10b to form a
cationic η2-silane complex intermediate, which, being
very sensitive to nucleophiles, was attacked by adventi-
tious water to generate the η2-H2 complex intermediate,
and finally the dihydrogen ligand was heterolytically
cleaved by the pendant amino group to give [(η5-
C5H4(CH2)3NMe2H+)RuH(dppm)]BAr′4. Brookhart et
al. proposed that hydrolysis of the η2-silane ligand in
[CpFe(CO)(L)(η2-HSiEt3)]+ (L ) PEt3, PPh3) by trace
moisture in the solvent was responsible for the forma-
tion of the dihydrogen complexes [CpFe(CO)(L)(η2-
H2)]+.35
Catalytic hydrogenation of CO2 to formic acid by
transition-metal complexes has attracted much interest
in recent years;36 although normal CO2 insertion into
the metal-hydride bond to generate a metal formate
complex seems to be in operation in most of the
successful catalytic systems, subsequent liberation of
formic acid may take a number of different routes.36i,l
A mechanism for the hydrogenation of CO2 to formic
acid with 9 or 10a is postulated and shown in Scheme
5. Therefore, reaction of 9 or 10a with H2 first forms
the dihydrogen complex intermediate, which rapidly
undergoes intramolecular heterolytic cleavage of η2-H2
to give 5H+ or 6H+. Insertion of CO2 into the metal-
hydride bond is believed to be a slow step, since 5H+ or
6H+ is the only detectable metal complex species
throughout the reaction. The main feature of this
scheme is protonation of the formato ligand by N-H of
the pendant amine arm to generate formic acid.
R ea ct ivit ies of [(η5:η1-C5H 4(CH 2)n NMe2)R u -
(d p p m )]+ t ow a r d H 2/CO2. Reactions of [(η5:η1-
C5H4(CH2)nNMe2)Ru(dppm)]+ with H2/CO2 have also
been studied. It was found that stirring a THF solution
of [(η5:η1-C5H4(CH2)2NMe2)Ru(dppm)]BF4 (9) at 80 °C
under H2/CO2 (40 atm/40 atm) for 16 h led to the
production of formic acid, albeit in low yield (TON
(36) See for example: (a) Tagui Khan, M. M.; Halligudi, S. B.;
Shukla, S. J . Mol. Catal. 1989, 57, 47. (b) Tsai, J . C.; Nicholas, K. M.
J . Am. Chem. Soc. 1992, 114, 5117. (c) Gassner, F.; Leitner, W. J .
Chem. Soc., Chem. Commun. 1993, 1465. (d) Leitner, W.; Dinjus, E.;
Gassner, F. J . Organomet. Chem. 1994, 475, 257. (e) J essop, P. G.;
Ikariya, T.; Noyori, R. Nature 1994, 368, 231. (f) Fornika, R.; Go¨rls,
H.; Seemann, B.; Leitner, W. J . Chem. Soc., Chem. Commun. 1995,
1479. (g) Lau, C. P.; Chen, Y. Z. J . Mol. Catal. A: Chem. 1995, 101,
33. (h) J essop, P. G.; Hsiao, Y.; Ikariya, T.; Noyori, R. J . Chem. Soc.,
Chem. Commun. 1995, 707. (i) J essop, P. G.; Ikariya, T.; Noyori, R.
Chem. Rev. 1995, 95, 259. (j) Leitner, W. Angew. Chem., Int. Ed. Engl.
1995, 34, 2207. (k) J essop, P. G.; Hsiao, Y.; Ikariya, T.; Noyori, R. J .
Am. Chem. Soc. 1996, 118, 344. (l) Hutschka, F.; Dedieu, A.; Eicherger,
M.; Fornika, R.; Leitner, W. J . Am. Chem. Soc. 1997, 119, 4432.
(34) Fryzuk, M. D.; Montgomery, C. D.; Rettig, S. J . Organometallics
1991, 10, 467.
(35) Scharrer, E.; Chang, S.; Brookhart, M. Organometallics 1995,
14, 5686.

2774 Organometallics, Vol. 17, No. 13, 1998
Chu et al.
Sch em e 5
Con clu sion
We have synthesized and characterized the ruthe-
nium complexes (η5-C5H4(CH2)nNMe2H+)RuH(dppm) (n
) 2, 3) in which the pendant amine functions are
protonated. The intramolecular N-H‚‚‚H-Ru proton-
hydride interaction in these complexes is evidenced by
the relaxation time T1 measurements. Results of a spin
saturation transfer study and H/D exchange experiment
with (η5-C5H4(CH2)3NMe2H+)RuH(dppm) are consistent
with the existence of a fast exchange process, via a
dihydrogen complex intermediate, between the hydride
ligand and the N-bound proton in the complex. The
complexes [(η5:η1-C5H4(CH2)nNMe2)Ru(dppm)]+ revers-
ibly add H2 to give (η5-C5H4(CH2)nNMe2H+)RuH(dppm);
the latter species are most likely formed by displace-
ment of the coordinated amine group by H2, followed
by deprotonation of the bound H2 by the now-pendant
amine arm. This reaction is an example of Ru-N bond
hydrogenolysis. We have recently reported a case of di-
rect involvement of the dihydrogen complex in catalytic
hydrogenation reactions, in which the crucial step is the
intermolecular deprotonation of the dihydrogen ligand
by additional base (B) to generate the metal hydride
(and BH+), and after the usual olefin coordination and
insertion steps, the final alkane product is produced via
alkyl group protonation by BH+.6c Our present work
points out that catalytic reactions can proceed by a simi-
lar mechanism, using complexes with tethered groups
which can function as internal bases. The proposed
mechanism of Scheme 5 provides such an example.
Reactions of 9 and 10a with sodium formate in re-
fluxing methanol gave (η5-C5H4(CH2)2NMe2)RuH(dppm)
(5) and (η5-C5H4(CH2)3NMe2)RuH(dppm) (6), respec-
tively (eq 5). Obviously, 5 and 6 were formed by ex-
pulsion of the CO2 molecule from the metal formate
intermediates.
Exp er im en ta l Section
All reactions were performed under an atmosphere of dry
nitrogen using standard Schlenk techniques. All chemicals
were obtained from Aldrich except dicyclopentadiene, which
was purchased from BDH. The ligands C5H5(CH2)nNMe2 (n
R ea ct ion
of
[(η5-C5H 4(CH 2)3NMe2H +)R u H -
(d p p m )]BF 4 (6H +) w it h Ca r bon Disu lfid e. While
the proposed metal formate intermediate shown in
Scheme 5 remains elusive in the high-pressure NMR
study, the analogous dithioformate complex 11 was
easily prepared by reacting 6H+ with excess CS2 (eq 6).
39
) 2, 3)38 and the complex RuCl2(PPh3)3 were prepared
according to published procedures. Solvents were distilled
under a dry nitrogen atmosphere with appropriate drying
agents (solvent/drying agent): ethanol/Mg-I2, methanol/Mg-
I2, tetrahydrofuran/Na-benzophenone, toluene/Na-benzo-
phenone, dichloromethane/P2O5, diethyl ether/CaH2, n-hexane/
Na. High-purity hydrogen gas was supplied by Hong Kong
Oxygen.
Infrared spectra were obtained on a Nicolet Magna 750 FT-
IR spectrophotometer. 1H NMR spectra were obtained from
a Bruker DPX 400 spectrometer. Chemical shifts (δ, ppm)
were reported relative to tetramethylsilane (TMS). 31P{1H}
and 13C{1H} NMR spectra were recorded on a Bruker DPX
400 spectrometer at 161.70 and 100.60 MHz, respectively. 31
chemical shifts were externally referenced to 85% H3PO4 in
D2O. 13C chemical shifts were internally referenced to the
residual peak of deuterated solvent. Relaxation time T1
P
Complex 11 was identified by IR and 1H NMR spec-
troscopy; its IR spectrum showed the characteristic
υ(CS2) band of the dithioformato ligand at 1040 cm-1
,
1
and its H NMR spectrum exhibited a singlet at 11.16
ppm which is diagnostic of the dithioformato proton. The
previously reported chemical shifts for unidentate and
bidentate dithioformate protons range from 9.5 to 14
ppm.37 The 31P{1H} NMR spectrum of 11 shows a sharp
singlet at δ 17.6 ppm, indicating that the two phospho-
rus atoms of dppm are equivalent and probably both
(37) See for example: (a) Harris, R. O.; Hota, N. K.; Sadvoy, L.;
Yuen, J . M. C. J . Organomet. Chem. 1973, 54, 259. (b) Robinson, S.
D.; Sahajpal, A. J . Organomet. Chem. 1975, 99, C65. (c) Robinson, S.
D.; Sahajpal, A. Inorg. Chem. 1977, 16, 2718. (d) Bruce, M. I.;
Humphrey, M. G.; Swincer, A. G.; Wallis, R. C. Aust. J . Chem. 1984,
37, 1747. (e) Bianchini, C.; Ghilardi, C. A.; Meli, A.; Midollini, S.;
Orlandini, A. Inorg. Chem. 1985, 24, 932. (f) J ia, G.; Meek, D. W. Inorg.
Chem. 1991, 30, 1953. (g) Albertin, G.; Antoniutti, S.; Del Ministro,
E.; Gordignon, E. J . Chem. Soc., Dalton Trans. 1994, 1769. (h) Albe´niz,
M.; Buil, M. L.; Esteruelas, M. A.; Lo´pez, A. M.; Oro, L. A.; Zeier, B.
Organometallics 1994, 13, 3746.
1
remain coordinated. Furthermore, the H NMR spec-
trum of 11 does not show any sign of η5 to η3/η1 Cp ring
slippage. Where all these facts are taken together, the
dithioformato ligand in 11 has to be unidentate to give
a electron count of 18.
(38) Rees, W. S., J r.; Dippel, K. A. Org. Prep. Proced. Int. 1992, 24,
527.
(39) Hallman, P. S.; Stephenson, T. A.; Wilkinson, G. Inorg. Synth.
1970, 12, 237.

Proton-Hydride Interaction in Ru Complexes
Organometallics, Vol. 17, No. 13, 1998 2775
measurements were carried out at 400 MHz by the inversion-
recovery method using the standard 180°-τ-90° pulse se-
quence. High-pressure NMR studies were carried out in a
sapphire HPNMR tube; the 10 mm sapphire NMR tube was
purchased from Saphikon, Milford, NH, while the titanium
high-pressure valve was constructed at the ISSECC-CNR,
Firenze, Italy. FAB MS was carried out with a Finnigan MAT
95S mass spectrometer using 3-nitrobenzyl alcohol as matrix.
Elemental analyses were performed by M-H-W Laboratories,
Phenix, AZ, and the Institute of Chemistry, Academia Sinica,
Beijing, China.
[(η5-C5H4(CH2)2NMe2H+)Ru Cl(P P h 3)2]Cl (1‚HCl). A so-
lution of RuCl3‚3H2O (0.45 g, 1.72 mmol) in 20 mL of ethanol
was refluxed for 5 min and then cooled to room temperature.
To the solution was added a 0.38 g (2.80 mmol) amount of the
ligand C5H5(CH2)2NMe2, and the mixture was then added to
a refluxing ethanol solution of PPh3 (2.70 g, 10.00 mmol). The
resulting mixture was stirred under reflux for 16 h. It was
then filtered at room temperature to remove some greenish
brown solids, and the filtrate was concentrated to one-third
its original volume. The concentrated filtrate was stored under
N2 overnight at -20 °C to give some orange microcrystals,
which were collected by filtration and dried in vacuo. Yield:
0.51 g (37%). Anal. Calcd for C45H45NP2Cl2Ru: C, 64.82; H,
5.44; N, 1.68. Found: C, 65.03; H, 5.52; N, 1.81. IR (KBr,
cm-1): ν(N-H) 2664 (br, w). 1H NMR (CDCl3, 400 MHz, 25
°C): δ 2.81 (t, 2H, J (HH) ) 8.1 Hz, C5H4CH2), 2.86 (d, 6H,
J (HH) ) 4.6 Hz, N-CH3), 3.27 (m, 2H, NCH2), 3.51 (br s, 2H
of Cp ring), 3.81 (br s, 2H of Cp ring), 7.10-7.35 (m, 30 H of
PPh3), 12.31 (br s, 1H, N-H). 31P{1H} NMR (CDCl3, 161.70
MHz, 25 °C): δ 41.2 (s).
of 3‚HCl, except 1 was used instead of 1‚HCl. Yield: 0.30 g
(82%). Anal. Calcd for C34H36NP2ClRu: C, 62.14; H, 5.52; N,
2.13. Found: C, 62.32; H, 5.48; N, 2.16. 1H NMR (CDCl3, 400
MHz, 25 °C): δ 2.31 (s, 6H, NCH3), 2.47 (m, 2H, NCH2), 2.60
2H, C5H4CH2), 3.99 (br s, 2H of Cp ring), 4.32 (m, 1H, PCHP),
4.85 (br s, 2H of Cp ring), 5.26 (m, 1H, PCHP), 7.36-7.73 (m,
20 H of dppm). 31P{1H} NMR (CDCl3, 161.70 MHz, 25 °C): δ
12.4 (s).
(η5-C5H4(CH2)3NMe2)Ru Cl(d p p m ) (4). This complex was
prepared by using the same procedure as for the preparation
of 3‚HCl, except 2 was used instead of 1‚HCl. Yield: 0.66 g
(79%). Anal. Calcd for C35H38NClP2Ru: C, 62.63; H, 5.71; N,
2.09. Found: C, 62.42; H, 5.51; N, 2.17. 1H NMR (CDCl3, 400
MHz, 25 °C): δ 1.80 (m, 2H, CH2CH2CH2), 2.21 (s, 6H, NCH3),
2.30 (m, 2H, NCH2), 2.32 (m, 2H, C5H4CH2), 4.01 (br s, 2H of
Cp ring), 4.42 (m, 1H, PCHP), 4.84 (br s, 2H of Cp ring), 5.31
(m, 1H, PCHP), 7.22-7.73 (m, 20 H of dppm). 31P{1H} NMR
(CDCl3, 161.70 MHz, 25 °C): δ 16.6 (s).
(η5-C5H4(CH2)2NMe2)Ru H(d p p m ) (5). Complex 3‚HCl
(0.16 g, 0.23 mmol) was added to 30 mL of NaOMe/MeOH (0.77
M) solution. The resulting solution was refluxed for 5 h, and
then the solvent was removed by vacuum. The residue was
extracted with 50 mL of toluene; and after removal of the
solvent, the yellow solid was washed with hexane (2 × 5 mL).
Yield: 0.09 g (62%). Anal. Calcd for C34H37NP2Ru: C, 65.57;
H, 5.99; N, 2.24. Found: C, 65.20; H, 5.97; N, 2.22. IR (KBr,
cm-1): ν(Ru-H) 1916 (m). 1H NMR (CD2Cl2, 400 MHz, 25
°C): δ -11.33 (td, J (HH) ) 3.4 Hz, J (HP) ) 31.5 Hz, 1H, RuH),
2.00 (s, 6H, NCH3), 2.16 (t, J (HH) ) 7.0 Hz, 2H, NCH2), 2.21
(t, J (HH) ) 6.9 Hz, 2H, C5H4CH2), 3.95 (m, 1H, PCHP), 4.78
(br s, 2H of Cp ring), 4.84 (br s, 2H of Cp ring), 4.90 (m, 1H,
PCHP), 6.98-7.62 (m, 20 H of dppm). 31P{1H} NMR (THF-
d8, 161.70 MHz, 25 °C): δ 22.7 (s). Complex 5 was also
prepared in 67% yield, from 3 instead of 3‚HCl, by following
the same procedure.
(η5-C5H4(CH2)3NMe2)Ru H(d p p m ) (6). This complex was
prepared by using the same procedure as for the preparation
of 5, except 4 is used in place of 3‚HCl or 3. Yield: 0.17 g
(66%). Anal. Calcd for C35H39NP2Ru: C, 66.02; H, 6.17; N,
2.20. Found: C, 65.96; H, 6.30; N, 2.14. IR (KBr, cm-1): ν-
(Ru-H) 1929 (m). 1H NMR (THF-d8, 400 MHz, 25 °C): δ
-11.14 (td, J (HH) ) 3.4 Hz, J (HP) ) 30.8 Hz, 1H, RuH), 1.64
(m, 2H, CH2CH2CH2), 2.11-2.18 (m, 10 H, C5H4CH2 + NCH2
+ NCH3), 3.98 (m, 1H, PCHP), 4.86 (br s, 2H of Cp ring), 4.91
(br s, 2H of Cp ring), 5.13 (m, 1H, PCHP), 7.34-7.85 (m, 20 H
of dppm). 31P{1H} NMR (THF-d8, 161.70 MHz, 25 °C): δ 23.0
(s). HRMS (FAB) (m/z): 636.1622 (M - H)+.
[(η5-C5H4(CH2)2NMe2H+)Ru Cl(d p p m )]Cl (3‚HCl). 1‚HCl
(0.47 g , 0.56 mmol) and dppm (0.23 g, 0.60 mmol) were
dissolved in 50 mL of toluene, and the solution was refluxed
for 16 h. The solvent was then removed by vacuum; the orange
residue was washed with diethyl ether (2 × 10 mL) and dried
in vacuo. Yield: 0.35 g (89%). Anal. Calcd for C34H37NP2-
Cl2Ru: C, 58.88; H, 5.38; N, 2.02. Found: C, 59.02; H, 5.51;
N, 2.10. IR (KBr, cm-1): ν(N-H) 2680 (br, w). 1H NMR
(CDCl3, 400 MHz, 25 °C): δ 2.62 (s, 6H, N-CH3), 2.86 (br s,
2H, C5H4CH2), 3.18 (br s, 2H, NCH2), 4.11 (br s, 2H of Cp ring),
4.39 (m, 1H, PCHP), 4.87 (m, 1H, PCHP), 4.97 (br s, 2H of Cp
ring), 7.20-7.68 (m, 20 H of dppm), 11.95 (br s, 1H, NH). 31P-
{1H} NMR (CDCl3, 161.70 MHz, 25 °C): δ 15.5 (s).
(η5-C5H4(CH2)2NMe2)R u Cl(P P h 3)2 (1). A THF (30 mL)
solution of KOtBu (0.17 g, 1.50 mmol) and C5H5(CH2)2NMe2
(0.30 g, 2.20 mmol) was stirred at room temperature for 30
min. The resulting solution was then transferred to a THF
(50 mL) solution of RuCl2(PPh3)3 (1.00 g, 1.04 mmol). The
solution mixture was stirred for 1 h; the solvent was then
removed by vacuum to afford an orange solid, which was
recrystallized from diethyl ether/hexane. Yield: 0.76 g (92%).
Anal. Calcd for C45H44NP2ClRu: C, 67.78; H, 5.57; N, 1.76.
Found: C, 67.68; H, 5.51; N, 1.83. 1H NMR (CDCl3, 400 MHz,
25 °C): δ 2.48 (s, 6H, NCH3), 2.60 (m, 2H, NCH2), 2.79 (br s,
2H, C5H4CH2), 3.39 (br s, 2H of Cp ring), 3.91 (br s, 2H of Cp
ring), 7.09-7.37 (m, 30 H of PPh3). 31P{1H} NMR (CDCl3,
161.70 MHz, 25 °C): δ 40.5 (s).
[(η5-C5H4(CH2)2NMe2H+)Ru H(d p p m )]BF 4 (5H+). HBF4•
Et2O (1.8 µL, 12.8 µmol) was added to a solution of 5 (0.008 g,
12.8 µmol) in 0.4 mL of THF-d8 in an NMR tube, and the NMR
spectra were collected immediately. 1H NMR (THF-d8, 400
MHz, 25 °C): δ -11.47 (t, J (HP) ) 30.3 Hz, 1H, RuH), 2.56
(s, 6H, NCH3), 2.71 (br s, 2H, NCH2), 3.28 (br s, 2H, C5H4CH2),
3.65 (br s, 1H, NH), 4.24 (m, 1H, PCHP), 4.74 (br s, 2H of Cp
ring), 5.17 (m, 1H, PCHP), 5.22 (br s, 2H of Cp ring), 7.41-
7.79 (m, 20 H of dppm). 31P{1H} NMR (THF-d8, 161.70 MHz,
25 °C): δ 21.7 (s).
[(η5-C5H 4(CH2)3NMe2H +)R u H (d p p m )]BF 4 (6H +). The
procedure for 5H+ was followed exactly. 1H NMR (THF-d8,
400 MHz, 25 °C): δ -11.31 (t, J (HP) ) 30.3 Hz, 1H, RuH),
1.89 (br s, 2H, CH2CH2CH2), 2.28 (br s, 2H, NCH2), 2.82 (s,
6H, NCH3), 3.09 (br s, 2H, C5H4CH2), 4.01 (br s, 2H of Cp ring),
4.03 (m, 1H, PCHP), 4.84 (br s, 2H of Cp ring), 5.11 (br s, 1H,
PCHP), 5.48 (br s, 1H, NH), 7.36-7.81 (m, 20 H of dppm). 31P-
{1H} NMR (THF-d8, 161.70 MHz, 25 °C): δ 23.1 (s).
Attempts to isolate 5H+ and 6H+ from their THF solution
by addition of hexane gave oily substances which failed to yield
solid products. Layering of hexane on THF solutions of 5H+
and 6H+ resulted in the formation of [(η5:η1-C5H4(CH2)2NMe2)-
Ru(dppm)]BF4 and [(η5:η1-C5H4(CH2)3NMe2)Ru(dppm)]BF4, re-
spectively.
(η5-C5H4(CH2)3NMe2)Ru Cl(P P h 3)2 (2). This complex was
prepared by using the same procedure as for the preparation
of 1, except that C5H5(CH2)3NMe2 was used in place of
C5H5(CH2)2NMe2. Yield: 1.31 g (88%). Anal. Calcd for
C
46H46NP2ClRu: C, 68.09; H, 5.71; N, 1.73. Found: C, 67.88;
H, 5.83; N, 1.89. 1H NMR (CDCl3, 400 MHz, 25 °C): δ 1.83
(m, 2H, CH2CH2CH2), 2.13 (s, 6H, NCH3), 2.32 (t, J (HH) )
7.4 Hz, 2H, NCH2), 2.50 (t, J (HH) ) 7.3 Hz, 2H, C5H4CH2),
4.13 (br s, 4H of Cp ring), 6.98-7.62 (m, 30 H of PPh3), 12.30
(br s, 1H, NH). 31P{1H} NMR (CDCl3, 161.70 MHz, 25 °C): δ
41.3 (s).
(η5-C5H4(CH2)2NMe2)Ru Cl(d p p m ) (3). This complex was
prepared by using the same procedure as for the preparation

2776 Organometallics, Vol. 17, No. 13, 1998
Chu et al.
[(η5-C5H4(CH2)2NMe2H+)Ru (H2)(d p p m )](BF 4)2 (7). Com-
plex 7 was prepared in an NMR tube by addition of 1 equiv of
HBF4‚Et2O to a THF-d8 solution of 5H+ or by addition of 2
equiv of HBF4•Et2O to a THF-d8 solution of 5 under N2. 1H
NMR (THF-d8, 400 MHz, 25 °C): δ -6.82 (br s, 2H, Ru(H2)),
2.75 (br s, 2H, NCH2), 3.03 (s, 6H, NCH3), 3.37 (br s, 2H,
C5H4CH2), 4.73 (m, 1H, PCHP), 5.60 (br s, 2H of Cp ring), 5.72
(m, 1H, PCHP), 5.79 (br s, 2H of Cp ring), 7.25-7.88 (m, 20 H
of dppm), 8.99 (br s, 1H, NH). 31P{1H} NMR (THF-d8, 161.70
MHz, 25 °C): δ 7.0 (s). Variable-temperature T1 measure-
ments on the H2 signal were carried out by the inversion-
recovery method using standard 180°-τ-90° pulse sequences.
T1 (THF-d8, 400 MHz, ms): 25 (293 K), 23 (283 K), 21 (273
K), 20 (263 K), 20 (253 K), 21 (243 K), 23 (233 K) 26 (223 K).
T1,min (20 ms at 260 K and 400 MHz) was obtained from the ln
T1 vs 1000/T plot.
2H, NCH2), 2.66 (m, 2H, C5H4CH2), 4.26 (br s, 2H of Cp ring),
5.20 (m, 1H, PCHP), 5.26 (br s, 2H of Cp ring), 5.70 (m, 1H,
PCHP), 7.39-8.16 (m, 32 H of dppm and Ar′). 31P{1H} NMR
(acetone-d6, 161.70 MHz, 25 °C): δ 7.5 (s).
[(η5-C5H4(CH2)3NMe2H+)Ru (η1-SCSH)(d p p m )]BF 4 (11).
To a solution of 6 (0.08 g, 0.12 mmol) in 4 mL of THF was
added HBF4‚Et2O (1.7 µL, 0.13 mmol) and CS2 (0.1 mL). The
solution was kept at room temperature for 3 days, and then
the solvent was removed by vacuum. The residue was washed
with 5 mL of hexane to afford a deep red solid. Yield: 0.10 g
(87%). Anal. Calcd for C36H40BNF4P2S2Ru: C, 54.01; H, 5.04;
N, 1.75. Found: C, 54.13; H, 5.11; N, 1.62. IR (KBr, cm-1):
ν(CS) 1040 (s). 1H NMR (THF-d8, 400 MHz, 25 °C): δ 1.95
(quint, J (HH) ) 7.8 Hz, 2H, CH2CH2CH2), 2.28 (t, J (HH) )
7.8 Hz, 2H, NCH2), 2.72 (s, 6H, NCH3), 2.92 (t, J (HH) ) 7.8
Hz, 2H, C5H4CH2), 4.49 (dt, J (HH) ) 14.7 Hz, J (HH) ) 11.3
Hz, 1H, PCHP), 4.77 (br s, 2H of Cp ring), 5.22 (dt, J (HH) )
14.7 Hz, J (HP) ) 10.0 Hz, 1H, PCHP), 5.34 (br s, 2H of Cp
ring), 7.33-7.53, 7.72 (m, 20 m of dppm), 11.16 (s, 1H, SCHS).
31P{1H} NMR (THF-d8, 161.70 MHz, 25 °C): δ 17.8 (s).
[(η5-C5H 4(CH 2)2NMe2D+)R u (H D)(d p p m )](BF 4)2 (7-d 2).
This compound was prepared in an NMR tube in THF-d8 by
reacting (η5-C5H4(CH2)2NMe2)RuH(dppm) (5; 0.012 g, 19.2
µmol) with DBF4 (6 µL, 52.0 µmol), which was prepared by
mixing 0.5 mL of D2O with 0.5 mL of HBF4‚Et2O. 1H NMR
CO2 Red u ction by 9 or 10a . A solution of 9 (0.012 g, 0.016
mmol) or 10a (0.012 g, 0.017 mmol) in 10 mL of THF was
heated under 80 atm of H2/CO2 (1/1) in a stainless steel
autoclave for 16 h. The reactor was cooled rapidly and
1
(THF-d8, 400 MHz, 25 °C): δ -6.85 (t, J (HD) ) 20.5 Hz).
[(η5-C5H4(CH2)3NMe2H+)Ru (H2)(d p p m )](BF 4)2 (8). The
complex was prepared using the same procedure as for the
preparation of 7, except that 6H+ and 6 were used instead of
5H+ and 5, respectively. 1H NMR (THF-d8, 400 MHz, 25 °C):
δ -6.72 (br s, 2H, Ru(H2)), 2.03 (br s, 2H, CH2CH2CH2), 2.32
(br s, 1H, NCH2), 2.99 (s, 6H, NCH3), 3.30 (br s, 2H, C5H4CH2),
4.54 (m, 1H, PCHP), 5.14 (br s, 2H of Cp ring), 5.68 (m, 1H,
PCHP), 5.77 (br s, 2H of Cp ring), 7.31-7.93 (m, 20 H of dppm).
31P{1H} NMR (THF-d8, 161.70 MHz, 25 °C): δ 13.2 (s).
Variable-temperature T1 measurements on the H2 signal were
carried out by the inversion-recovery method using standard
180°-τ-90° pulse sequences. T1 (THF-d8, 400 MHz, ms): 23
(293 K), 23 (283 K), 21 (273 K), 20 (263 K) 20 (253 K), 21 (243
K) 24 (233 K), 26 (223 K). T1,min (20 ms at 255 K and 400
MHz) was obtained from the ln T1 vs 1000/T plot.
1
carefully vented. The formic acid formed was analyzed by H
NMR.
Rea ction of 9 or 10a w ith CO2/H2 in a n HP NMR Tu be.
A THF-d8 solution of 9 or 10a in the HPNMR tube was pres-
surized with 80 atm of H2/CO2 (1/1). 31P{1H} spectra of the
solution were taken at 60 °C every 2 h for a period of 18 h.
Rea ction of 10b w ith P h 2SiH2. Ph2SiH2 (4 µL, 22 µmol)
was added through a microsyringe to a 0.4 mL THF-d8 solu-
tion of 10b (18 mg, 12 µmol) in a 5 mm NMR tube sealed
with a rubber septum. The solution was heated in the
NMR probe at 50 °C for 2 h and 1H and 31P{1H} spectra
taken indicated that a small amount of 6H+ was formed. The
tube was continuously heated at 50 °C in the probe, and the
NMR spectra were recorded every 2 h for a period of 14 h. It
was shown by 1H and 31P{1H} NMR that, at the end of the
period, ∼80% of 10b had been converted to 6H+ and these two
were the only metal complexes present throughout the experi-
ment.
[(η5-C5H 4(CH 2)3NMe2D+)R u (H D)(d p p m )](BF 4)2 (8-d 2).
The procedure for 7-d 2 was followed exactly, except that 6 was
used instead of 5. 1H NMR (THF-d8, 400 MHz, 25 °C): δ -6.69
1
(t, J (HD) ) 21.5 Hz).
[(η5:η1-C5H4(CH2)2NMe2)Ru (d p p m )]BF 4 (9). A mixture
of (η5-C5H4(CH2)2NMe2)RuCl(dppm) (3; 0.50 g, 0.76 mmol) and
NaBF4 (0.08 g, 0.76 mmol) in 20 mL of MeOH was stirred at
50 °C for 16 h, and then the solvent of the orange solution
was removed by vacuum. The orange residue was washed
with a few 10 mL portions of diethyl ether and dried in vacuo.
Yield: 0.47 g (85%). Anal. Calcd for C34H36BNF4P2Ru: C,
Cr ysta llogr a p h ic An a lysis for [(η5:η1-C5H4(CH2)3NMe2)-
Ru (d p p m )]BP h 4 (10c). Crystals suitable for an X-ray dif-
fraction study were obtained by layering of hexane on a THF
solution of [(η5-C5H4(CH2)3NMe2H+)RuH(dppm)]BF4 (6H +)
containing 5 equiv of NaBPh4. An orange block-shaped crystal
of dimensions 0.19 × 0.19 × 0.29 mm was mounted in a glass
capillary and used for X-ray structure determination. All
measurements were made on a Marreserach image plate
scanner with graphite-monochromated Mo KR radiation. The
crystal system is found to be monoclinic and the space group
P21(No. 4) was found from the systematic absences and
confirmed by successful solution and refinement. The data
were collected at 25 °C using the ω-scan technique to a
maximum 2θ value of 51.3°. Of the 16 719 reflections which
were collected, 4410 were unique (Rint ) 0.037); equivalent
reflections were merged. The linear absorption coefficient, µ,
for Mo KR radiation is 4.3 cm-1. The structure was solved by
the Patterson method and expanded using Fourier techniques
with the teXsan crystallographic software package. All non-H
atoms except B were refined anisotropically. Hydrogen atoms
were included but not refined. The final cycle of full-matrix
least-squares refinement was based on 4223 observed reflec-
tions (I > 3.00σ(I)) and 571 variable parameters and converged
with unweighted and weighted agreement factors R ) 2.4%
and Rw ) 3.0% with GOF ) 1.20. The data to parameter ratio
was 7.41:1 and residual electron density/hole +0.33/-0.68
1
57.64; H, 5.12; N, 1.98. Found: C, 57.96; H, 5.22; N, 1.89. H
NMR (acetone-d6, 400 MHz, 25 °C): δ 2.45 (s, 6H, NCH3), 2.49
(m, 2H, NCH2), 2.73 (m, 2H, C5H4CH2), 4.70 (m, 1H, PCHP),
4.35 (br s, 2H of Cp ring), 5.45 (br s, 2H of Cp ring), 5.88 (m,
1H, PCHP), 7.47-8.16 (m, 20 H of dppm). 31P{1H} NMR
(acetone-d6, 161.70 MHz, 25 °C): δ 7.5 (s).
[(η5:η1-C5H4(CH2)3NMe2)Ru (d p p m )]BF 4 (10a ). The pro-
cedure for 9 was followed exactly, except that 4 was used
instead of 3. Yield: 0.65
g (90%). Anal. Calcd for
C
35H38BNF4P2Ru: C, 58.18; H, 5.30; N, 1.94. Found: C, 58.23;
H, 5.41; N, 1.88. 1H NMR (CD3OD, 400 MHz, 25 °C): δ 2.15
(m, 2H, CH2CH2CH2), 2.41 (s, 6H, NCH3), 2.47 (m, 2H, NCH2),
2.74 (m, 2H, C5H4CH2), 4.31 (br s, 2H of Cp ring), 5.26 (m,
1H, PCHP), 5.35 (br s, 2H of Cp ring), 5,74 (m, 1H, PCHP),
7.49-8.08 (m, 20 H of dppm). 31P{1H} NMR (acetone-d6,
161.70 MHz, 25 °C): δ 7.1 (s).
[(η5:η1-C5H4(CH2)3NMe2)Ru (d p p m )]BAr ′4 (10b; Ar ′ ) 3,5-
(CF 3)2C6H3). This complex was prepared by using the same
procedure as for the preparation of 10a , except that NaBAr′4
was used in place of NaBF4. Yield: 1.18 g (79%). Anal. Calcd
for C67H50BNF24P2Ru: C, 53.68; H, 3.36; N, 0.93. Found: C,
54.13; H, 3.27; N, 0.91. 1H NMR (acetone-d6, 400 MHz, 25
°C): δ 2.05 (m, 2H, CH2CH2CH2), 2.34 (s, 6H, NCH3), 2.39 (m,
e-Å-3
distances and angles are given in Tables 1 and 2, respectively.
. Further crystallographic details and selected bond

Proton-Hydride Interaction in Ru Complexes
Organometallics, Vol. 17, No. 13, 1998 2777
all bond lengths and bond angles, anisotropic displacement
coefficients, and isotropic displacement coefficients for [(η5:η1-
C5H4(CH2)3NMe2)Ru(dppm)]BPh4 (26 pages). Ordering infor-
mation is given on any current masthead page.
Ack n ow led gm en t. We thank the Hong Kong Poly-
technic University and the Hong Kong Research Grant
Council (Project No. PolyU 32/96P) for financial support.
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates and equivalent isotropic displacement coefficients,
OM980071V