Unexpected formation of the isopropylamine complex [2,3,4,5-Ph4(η4-C4CO)](CO)2Ru(H 2NCHME2) in the attempted synthesis of an isopropyl alcohol complex

Article abstract of DOI:10.1021/om020097t

The reaction of [2,3,4,5-Ph₄(η⁴-C₄CO)]Ru(CO)₃ (5a) with Na₂CO₃ in aqueous acetone followed by low-temperature treatment with NH₄Cl was reported to give the material A, which was formulated as the isopropyl alcohol complex [2,3,4,5-Ph₄(η⁴-C₄CO)](CO)₂Ru(HO CHMe₂) (3a). Reinvestigation of this reaction indicates that A is instead the isopropylamine complex [2,3,4,5-Ph₄(η⁴-C₄CO)](CO)₂Ru(H ₂NCHMe₂) (4a). The formation of 4a is proposed to occur by formation of the imine of acetone followed by reduction of the imine by the (hydroxycyclopentadienyl)ruthenium hydride [2,3,4,5-Ph₄(η⁵-C₄COH)]Ru(CO)₂H (2a) formed in the reaction of 5a with Na₂CO₃ in aqueous acetone and subsequent acidification with aqueous NH₄Cl.

Full text of DOI:10.1021/om020097t

Organometallics 2002, 21, 1955-1959
1955
Un exp ected F or m a tion of th e Isop r op yla m in e Com p lex
[2,3,4,5-P h 4(η4-C4CO)](CO)2Ru (H2NCHMe2) in th e
Attem p ted Syn th esis of a n Isop r op yl Alcoh ol Com p lex
Charles P. Casey* and Galina A. Bikzhanova
Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706
J an-E. Ba¨ckvall* and Lars J ohansson
Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University,
SE-106 91 Stockholm, Sweden
J aiwook Park* and Yu Hwan Kim
Department of Chemistry, Center for Integrated Molecular System, Pohang University of
Science and Technology (POSTECH), San 31 Hyoja Dong, Pohang 790-784, Republic of Korea
Received February 8, 2002
The reaction of [2,3,4,5-Ph4(η4-C4CO)]Ru(CO)3 (5a ) with Na2CO3 in aqueous acetone
followed by low-temperature treatment with NH4Cl was reported to give the material A,
which was formulated as the isopropyl alcohol complex [2,3,4,5-Ph4(η4-C4CO)](CO)2Ru-
(HOCHMe2) (3a ). Reinvestigation of this reaction indicates that A is instead the isopropyl-
amine complex [2,3,4,5-Ph4(η4-C4CO)](CO)2Ru(H2NCHMe2) (4a ). The formation of 4a is
proposed to occur by formation of the imine of acetone followed by reduction of the imine by
the (hydroxycyclopentadienyl)ruthenium hydride [2,3,4,5-Ph4(η5-C4COH)]Ru(CO)2H (2a )
formed in the reaction of 5a with Na2CO3 in aqueous acetone and subsequent acidification
with aqueous NH4Cl.
Sch em e 1
In tr od u ction
Shvo’s diruthenium hydride complex {[2,3,4,5-Ph4(η5-
C4CO)]2H}Ru2(CO)4(µ-H) (1a ) is an efficient catalyst for
the hydrogenation of aldehydes and ketones1 and is also
very useful in the transfer hydrogenation of ketones
using alcohols as the reducing agent.2 In the reduction
of ketones to alcohols, the mononuclear [2,3,4,5-Ph4(η5-
C4COH)]Ru(CO)2H (2a ) has been proposed to be the
active reducing agent and has been shown to reduce
aldehydes and ketones (Scheme 1).1b,c
Since the reduction of ketones could initially produce
an alcohol complex, the role of alcohol complexes in
these reduction systems needs to be considered, even
though they have never been directly observed in the
reaction mixtures. On the basis, in part, of the observa-
tion of related amine complexes, Shvo proposed that
reduction of ketones by 2a initially produced alcohol
complexes (Scheme 2).3 Ba¨ckvall2 and Shvo1 have both
proposed mechanisms for ketone reduction by 2a that
(1) (a) Shvo, Y.; Czarkie, D.; Rahamim, Y. J . Am. Chem. Soc. 1986,
108, 7400. (b) Menashe, N.; Shvo, Y. Organometallics 1991, 10, 3885.
(c) Menashe, N.; Salant, E.; Shvo, Y. J . Organomet. Chem. 1996, 514,
97.
(2) (a) Almeida, M. L. S.; Beller, M.; Wang, G.-Z.; Ba¨ckvall, J . E.
Chem. Eur. J . 1996, 2, 1533. (b) Larsson, A. L. E.; Persson, B. A.;
Ba¨ckvall, J . E. Angew. Chem., Int. Ed. Engl. 1997, 36, 1211. (c) Persson,
B. A.; Larsson, A. L. E.; Le Ray, M.; Ba¨ckvall, J . E. J . Am. Chem. Soc.
1999, 121, 1645. (d) Persson, B. A.; Huerta, F. F.; Ba¨ckvall, J . E. J .
Org. Chem. 1999, 64, 5237. (e) Huerta, F. F.; Laxmi, Y. R. S.; Ba¨ckvall,
J . E. Org. Lett. 2000, 2, 1037. (f) Laxmi, Y. R. S.; Ba¨ckvall, J . E. Chem.
Commun. 2000, 611.
involve oxygen coordination to Ru followed by hydride
migration to the ketone carbonyl carbon that results in
the direct formation of an alcohol complex. For the
microscopic reverse, Ba¨ckvall proposes â-hydride elimi-
nation from the alcohol complex.
Since â-hydride elimination normally requires a
vacant coordination site at the metal and since the
resulting ketone complex is formally a 20e system,
(3) Abed, M.; Goldberg, I.; Stein, Z.; Shvo, Y. Organometallics 1988,
7, 2054.
10.1021/om020097t CCC: $22.00 © 2002 American Chemical Society
Publication on Web 03/30/2002

1956 Organometallics, Vol. 21, No. 9, 2002
Casey et al.
Sch em e 2
Sch em e 4
Sch em e 5
Sch em e 3
MS, 1H and 13C NMR, and IR spectroscopy data of
Park’s complex A were said to support the proposed
formulation as the isopropyl alcohol complex [2,3,4,5-
Ph4(η4-C4CO)](CO)2Ru(HOCHMe2) (3a ).
Because of the importance of alcohol complexes in the
mechanism of carbonyl reductions by RuH, the groups
of Casey and Ba¨ckvall decided to collaborate on studies
of Park’s “alcohol complex” A. The Stockholm group
synthesized the material A, and the Wisconsin group
synthesized the related compound A* with p-tolyl
groups to aid in NMR spectroscopy studies.
Here we report that Park’s “alcohol complex” A is
actually the isopropylamine complex [2,3,4,5-Ph4(η4-C4-
CO)](CO)2Ru(H2NCHMe2) (4a ). Park’s group has rein-
terpreted their data and are in agreement that A is the
isopropylamine complex 4a .
Ba¨ckvall has suggested that η5- to η3-ring slippage may
be involved in these reactions (Scheme 3).4-5
Casey has studied the kinetics of the reduction of
benzaldehyde by the related tolyl complex [2,5-Ph2-3,4-
Tol2(η5-C4COH)]Ru(CO)2H (2b) and found deuterium
isotope effects for both OD and RuD substitution that
require simultaneous transfer of a proton from the OH
group to the aldehyde oxygen and transfer of hydride
from Ru to carbon.6 Casey has proposed that benzalde-
hyde reduction occurs outside the coordination sphere
of Ru (Scheme 4). The formation of an alcohol complex
after the rate-determining step and its rapid reaction
with excess RuH to give a diruthenium complex is a
possibility.
Recently, Park reported the synthesis of the ruthe-
nium complex A by several routes, all of which involved
acetone and a ruthenium complex and low-temperature
protonation of supposed intermediates with NH4Cl
(Scheme 5).7 Elemental analysis, X-ray crystallography,
Resu lts
Of Park’s three routes to A, the highest purity and
yield came from reaction of dienone complex 5a with
Na2CO3 in acetone-water followed by treatment with
NH4Cl at 0 °C. The Stockholm group reproduced the
Park procedure and obtained material A in 44% yield.
The Wisconsin group followed a related procedure,
starting with the tolyl-substituted dienone complex 5b,
and obtained a 32% yield of the tolyl analogue A*, which
had properties similar to those reported by Park for A.
P r oblem s w ith th e “CHOH” 1H NMR Reson a n ces
(4) Csjernyik, G.; EÄ ll, A. H.; Fadini, L.; Pugin, B.; Ba¨ckvall, J . E. J .
Org. Chem. 2002, 67, 1657.
(5) Shvo proposed that the hydrogenation of alkenes and alkynes
1
of A. The H NMR spectra obtained were very similar
proceeds through
a ring-slip mechanism: Shvo, Y.; Goldberg, I.;
to those reported by Park, with a major exception. Both
groups noted that the resonance that had been assigned
to the OH proton (δ 2.44, br s, 1H) was integrated for
about 2H and appeared as a broad split peak with peak
Czerkie, D.; Reshef, D.; Stein, Z. Organometallics 1997, 16, 133.
(6) Casey, C. P.; Singer, S. W.; Powell, D. R.; Hayashi, R. K.; Kavana,
M. J . Am. Chem. Soc. 2001, 123, 1090.
(7) J ung, H. M.; Shin, S. T.; Kim, Y. H.; Kim, M.-J .; Park, J .
Organometallics 2001, 20, 3370.

Unexpected Formation of an Isopropylamine Complex
Organometallics, Vol. 21, No. 9, 2002 1957
Sch em e 6
to observe “exchange” with isopropyl alcohol, A* was
heated at 80 °C in the presence of (CD3)2CDOD, but no
changes in spectra were observed. Similarly, no reaction
of A* with benzyl alcohol was seen up to 80 °C. In the
mechanism for ketone reduction proposed by Casey
(Scheme 4), the formation of an alcohol complex after
the rate-determining step was considered as a possibil-
ity only if it reacted rapidly with excess ruthenium
hydride 2b to give the diruthenium hydride 1b. How-
ever, no reaction of A* with hydride complex 2b was
seen below 80 °C, and no formation of diruthenium
bridging hydride 1b was observed. PPh3 reacted with
A* slowly at 80 °C to form the known phosphine
complex [2,5-Ph2-3,4-Tol2(η4-C4CO)](CO)2RuPPh3 (7b)
(Scheme 6).
In Ba¨ckvall’s mechanism for alcohol oxidation (Scheme
3), an isopropyl alcohol complex would be expected to
undergo rapid and reversible conversion to acetone and
a (dienone)Ru(CO)2 intermediate. However, when the
Park material A was heated in acetone-d6 at 70 °C in a
sealed NMR tube, no incorporation of coordinated
deuterated isopropyl alcohol or evolution of nondeuter-
ated acetone was observed.
separation of about 5 Hz. In an attempt to remove water
that might have been responsible for the high integra-
tion and the observation of two peaks, the NMR solvents
and ruthenium complexes were rigorously dried; how-
ever, the spectra were unchanged. 1H NMR spectra were
taken at both 300 and 500 MHz to determine whether
the two peaks at δ 2.44 were due to two chemical shifts
or to coupling. The peak separation remained at about
5 Hz, indicative of coupling, not a chemical shift
difference. 2D COSY 1H NMR spectra of A demon-
strated that the 2H resonance at δ 2.44 was coupled to
the 1H “septet” at δ 2.87. When the “septet” resonance
for the CHMe2 group at δ 2.87 was blown up, the
resonance was found to be a nonet (nine lines). The
intensities of the seven inner lines of the δ 2.87
resonance were much closer to those expected for a
nonet (inner seven lines 1:3.5:7:8.75:7:3.5:1) than for a
true septet (1:6:15:20:15:6:1).8 Moreover, when the δ
2.44 signal in the 1H NMR spectrum was selectively
irradiated, the coupling pattern and peak intensities of
the signal at δ 2.87 were indeed changed to the feature
expected for a true septet.
Rein ter p r eta tion of A a n d A* a s Isop r op yla m in e
1
Com p lexes. The H NMR spectra and the much lower
than expected reactivity of A and A* are inconsistent
with the formulation of A as the isopropyl alcohol
complex 3a . We are now convinced that the compounds
are in fact isopropylamine complexes 4a ,b. The nonet
at δ 2.87 for the CHMe2 resonance of A is now explained
by equal coupling to two NH2 hydrogens and six methyl
hydrogens; the chemical shift is in better agreement
with a hydrogen R to nitrogen rather than to oxygen.
The 2H integration of the δ 2.44 resonance is now
attributed to the NH2 group. The spectral properties of
A and A* are similar to those of Shvo’s diethylamine
complex [2,3,4,5-Ph4(η4-C4CO)]Ru(CO)2(NHEt2) (8)3,9
and Casey’s benzyl(methyl)amine complex [2,5-Ph2-3,4-
Tol2(η4-C4CO)]Ru(CO)2NH(CH3)(CH2Ph) (9).10 In the 1H
NMR spectrum of 8 in C6D6, the chemical shift of the
CH2N resonance is δ 2.35 and the couplings of the NH
hydrogen to the diastereotopic CH2 hydrogens are 5.0
and 5.8 Hz. In the 1H NMR spectrum of benzyl(methyl)-
amine complex 9 in CD2Cl2, the chemical shift of the
NH resonance is δ 1.66, the couplings of the NH
hydrogen to the diastereotopic benzyl CH2 hydrogens
are 11.3 and 2.4 Hz, and that to the methyl hydrogens
is 5.8 Hz. Shvo reported that the NH resonance of 8
persisted in D2O but was washed out upon addition of
DCl.
P r oblem s w ith Exch a n ge Rea ction s of A. Before
the additional NMR spectroscopy data detailed above
were obtained and on operating with the presumption
(in scientific method terminology, “working hypothesis”)
that A and A* were alcohol complexes, both the Wis-
consin and Stockholm groups began studies of the
reactivity of A and A*. These studies were at variance
with the expected properties of alcohol complexes and
led to questioning of the structures of A and A* and to
1
a more careful examination of H NMR spectroscopy
data as described above.
Alcohol complexes would be expected to rapidly
exchange their OH proton with D2O. However, when
D2O was added to a solution of either A or the tolyl
analogue A*, the 2H resonance at δ 2.44 assigned to an
“OH” group was not washed out until the solutions were
heated at 80 °C (Scheme 6). This slow exchange is
unexpected for an OH group.
Alcohol complexes would be expected to undergo
exchange of the alcohol ligand. (Park mentioned the
“Unexpected Stability of the Alcohol Complex” in the
title of his paper.) The Wisconsin group also found A*
to be very unreactive toward substitution. In an attempt
In d ep en d en t Syn th esis of Isop r op yla m in e Com -
p lexes. The structural assignment of A and A* as
isopropylamine complexes 4a and 4b was confirmed by
independent synthesis. Compound 4a was prepared in
73% yield from 5a and isopropylamine analogously to
Shvo’s synthesis of the diethylamine complex [2,3,4,5-
Ph4(η4-C4CO)]Ru(CO)2(NHEt2) (8)3 (Scheme 7). Reaction
of isopropylamine with the dienone diruthenium com-
(9) Shvo, Y.; Abed, M.; Blum, Y.; Laine, R. M. Isr. J . Chem. 1986,
27, 267.
(8) Park’s 1H NMR spectra of A also showed integration for 2H for
the two peaks at δ 2.44 and approximately 1:3.5:7:8.75:7:3.5:1 intensity
for the seven inner lines of the δ 2.87 resonance. These discrepancies
were initially attributed to the presence of water as an impurity.
(10) Selected resonances from 1H NMR of 9 (CD2Cl2, 250 MHz): δ
3
1.66 (br m, NH), 2.40 (d, 3J ) 5.8 Hz, NCH3), 3.58 (ABX, J AB ) 13.1
3
3
3
Hz, J AX ) 11.3 Hz, NCHH), 3.77 (ABX, J AB ) 13.1 Hz, J BX ) 2.4
Hz, NCHH).6

1958 Organometallics, Vol. 21, No. 9, 2002
Casey et al.
Sch em e 7
plex 6b gave a high yield of the isopropylamine complex
4b. The properties of 4a ,b were identical with those of
A and A*.
Rein ter p r eta tion of X-r a y, Ma ss Sp ectr om etr y,
a n d E lem en t a l An a lysis Da t a of A. The X-ray
structure data for A reported by Park included a 50:50
disorder for the OH hydrogen, with half-occupancy of a
site intramolecularly hydrogen bonded to the dienone
oxygen and half-occupancy of a site intermolecularly
hydrogen bonded. The alcohol formulation 3a and amine
complex 4a have the same total number of electrons.
When the structure of A was modeled with the two
hydrogen-bonded sites fully occupied (an additional half-
electron each) and nitrogen in place of oxygen (one
electron less), the values of R1 ) 0.0298, wR2 ) 0.0837,
and goodness of fit on F2 of 1.123 improved slightly to
R1 ) 0.0286, wR2 ) 0.0813, and goodness of fit on F2
of 1.054.11 The bond distances to the heteroatom did not
change significantly: Ru-O ) 2.189(2) Å changed to
Ru-N ) 2.1882(18) Å, and O-C ) 1.497(4) Å changed
to N-C ) 1.497(3) Å (Figure 1).
F igu r e 1. X-ray structure of isopropylamine complex 4a .
Sch em e 8
The molecular weight of alcohol formulation 3a is 1
greater than that of the amine complex 4a . Park’s low-
resolution mass spectrum of A was obtained using the
FAB method with 3-nitrobenzyl alcohol as the matrix
material. The most intense peak in the isotopic cluster
in the molecular ion region was found at m/z 602.16 and
was assigned to the M+ ion of 3a . The m/z 602 peak is
now assigned to the (M + H)+ peak for the protonated
amine complex;12 FAB spectra typically give (M + H)+
peaks when basic sites are available. The Stockholm
group performed a MALDI-TOF MS on A with 2,5-
dihydroxybenzoic acid as matrix, which gave the (M +
H)+ peak at m/z 602.1 (calcd for C34H30NO3102Ru, m/z
602.13) accompanied by an isotope pattern in good
agreement with a simulated spectrum based on isotope
distribution. For the tolyl derivative 4b, the high-
resolution electrospray mass spectrum obtained using
a CHCl3/MeOH solution (measured m/z 630.1568) al-
lowed a clear distinction between (M + H)+ of the amine
complex 4b (calcd for C36H34NO3102Ru m/z 630.1592)
and M+ of alcohol complex 3b (calcd for C36H32O4102Ru
m/z 630.1354).
establishing composition and purity, the C,H analyses
expected for alcohol complex 3a (C, 67.87; H, 4.69) and
for amine complex 4a (C, 67.98; H, 4.87) are not
experimentally distinguishable. Only O or N analysis
would have distinguished 3a from 4a , and O analyses
are rarely performed and N analysis is normally done
only for compounds thought to contain nitrogen. Nitro-
gen analyses of A13 and A* have now been performed
and are consistent with their formulation as isopropyl-
amine complexes 4a and 4b.
P r oba ble Mod e of F or m a tion of Isop r op yla m in e
Com p lex. It is proposed that amine complexes 4a and
4b are formed by reaction of the imine of acetone with
the (hydroxycyclopentadienyl)ruthenium hydrides 2a ,b
(Scheme 8). In all of the syntheses, the reaction mix-
tures contained acetone and NH4Cl, which in the
presence of Na2CO3 would be in equilibrium with the
corresponding imine or iminium compound. Earlier,
Casey reported that imines are exceedingly reactive
While the ritual burning of compounds to obtain
elemental analyses is often cited as a method for
(11) The revised crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre (CCDC 176947).
(12) Isotope pattern for (M + H)+ of 4a : m/z (calcd, obsd) 605 (19,
22), 604 (54, 59), 603 (34, 47), 602 (100, 100), 601 (58, 62), 600 (45,
68).
(13) The Park group has obtained the following C,H,N analysis for
A that is consistent with its formulation as the amine complex 4a .
Anal. Calcd for C34H29NO3Ru: C, 67.99; H, 4.87; N, 2.33. Found: C,
67.97; H, 4.74; N, 2.40.

Unexpected Formation of an Isopropylamine Complex
Organometallics, Vol. 21, No. 9, 2002 1959
mL) and H2O (2 mL). The reaction mixture was stirred for 2
h, after which a workup procedure similar to that described
in procedure A gave 4a in 73% yield.
toward (hydroxycyclopentadienyl)ruthenium hydride 2b
and produce amine complexes.6 We suggest that the
(hydroxycyclopentadienyl)ruthenium hydrides 2a ,b are
formed by protonation of an anionic hydride intermedi-
ate formed in reactions of 2 with base, of 5 with base,
and of 6 with base followed by isopropyl alcohol.
Previously, Shvo reported that protonation of similar
reaction mixtures at room temperature leads to the
formation of the diruthenium hydride complex 1a as the
major product.1 In separate experiments that involved
the concentration of the reaction mixture before acidi-
fication or the extension of reaction time, Park showed
that the anionic diruthenium hydride complex [2,3,4,5-
Ph4(η5-C4CO)]2Ru2(CO)4(µ-H)- was formed quantita-
tively and that the acidification of the acetone solution
of the anionic diruthenium hydride complex with aque-
ous NH4Cl led to the formation of diruthenium hydride
complex 1a exclusively.
[2,5-P h 2-3,4-Tol2(η4-C4CO)](CO)2R u (H 2NCH Me2) (4b ).
P r oced u r e A. A saturated aqueous solution of Na2CO3 (25
mL) was added to a solution of 6 (630 mg, 0.55 mmol) in
acetone (25 mL) at room temperature. After the mixture was
stirred for 30 min, isopropyl alcohol (25 mL) was added and
stirring was continued for another 30 min. The reaction
mixture was acidified by addition of a saturated aqueous NH4-
Cl solution (50 mL) at room temperature and concentrated
under vacuum. The residue was extracted with CH2Cl2 and
chromatographed on silica gel with 6:1 CH2Cl2/ethyl acetate
to give 4b. Recrystallization of 4b from 3:1 hexane/CH2Cl2 at
-10 °C gave air-stable pale yellow crystals of 4b (220 mg,
1
3
32%). H NMR (CDCl3, 500 MHz): δ 0.97 (d, J ) 6.5 Hz, 6H,
3
isopropyl CH3), 2.22 (s, 6H, tolyl CH3), 2.41 (br d, J ≈ 5 Hz,
2H, NH2), 2.86 (nonet, 3J ) 6.5 Hz, 1H, CHMe2), 6.89 (d, 3J )
3
8.5 Hz, 4H, tolyl), 7.04 (d, J ) 8.0 Hz, 4H, tolyl), 7.09-7.17
(m, 6H, phenyl), 7.56 (d, 3J ) 7.5 Hz, 4H, phenyl). 13C{1H}
NMR (CDCl3, 125 MHz): δ 21.1 (tolyl CH3), 24.5 (isopropyl
CH3), 51.3 (CHMe2), 83.3 (2C of Cp), 103.2 (2C of Cp), 126.2
(2 C, aromatic), 127.6 (4C, aromatic), 128.3 (4C, aromatic),
128.5 (2C, aromatic), 130.1 (4C, aromatic), 131.9 (4C, aro-
matic), 132.8 (2C, aromatic), 137.2 (2C, aromatic), 162.8 (1C
of Cp), 201.0 (CO). IR (CD2Cl2): 2012 (s), 1934 (s) cm-1. MS
(electrospray ionization, CHCl3, MeOH): m/z (M + H)+ calcd
for C36H34NO3102Ru 630.1592; calcd for C36H32O4102Ru 630.1354,
found 630.1568. Isotope pattern for (M + H)+ of 4b: m/z (calcd,
obsd) 633 (12, 14), 632 (54, 38), 631 (37, 28), 630 (100, 100),
Con clu sion . Be wary when all data does not fit a
preconceived formulation! The importance of alcohol
complexes remains, and all three groups will continue
to search for routes to such intermediates to test their
role in the mechanism of reduction.
Exp er im en ta l Section
[2,3,4,5-P h 4(η4-C4CO)](CO)2Ru (H2NCHMe2) (4a ). P r o-
ced u r e A. A saturated aqueous solution of Na2CO3 (15 mL)
was added to a solution of 5a (205 mg, 0.36 mmol) in acetone
(15 mL) at ambient temperature. After it was stirred for 1 h,
the reaction mixture was cooled to 0 °C and acidified by
addition of a saturated aqueous solution of NH4Cl (25 mL).
After concentration under vacuum, the residue was extracted
with CH2Cl2 and chromatographed on silica gel (6:1 CH2Cl2/
ethyl acetate) to give 4a as a pale yellow powder (95 mg, 44%).
1H NMR (CDCl3, 300 MHz): δ 0.98 (d, 3J ) 6.3 Hz, 6H,
629 (58, 45), 628 (45, 43), 627 (34, 28). Anal. Calcd for C36H33
-
NO3Ru: C, 68.77; H, 5.29; N, 2.23. Found: C, 68.79; H, 5.30;
N, 1.92.
P r oced u r e B. Isopropylamine (5 µL, 0.06 mmol) was added
via syringe to a CD2Cl2 suspension of 6b (33 mg, 0.03 mmol),
and the mixture was stirred for 30 min, until all the material
dissolved. Solvent was removed under vacuum to afford 4b
(30 mg, 80%).
3
isopropyl CH3), 2.44 (br d, J ≈ 5 Hz, 2H, NH2), 2.87 (nonet,
3J ) 6.3 Hz, 1H, CHMe2), 7.04-7.20 (m, 16H, phenyl), 7.56
(d, 3J ) 8.2 Hz, 4H, phenyl). 13C{1H} NMR (CDCl3, 100 MHz):
δ 24.7 (isopropyl CH3), 51.6 (CHMe2), 83.4 (2C of Cp), 103.7
(2C of Cp), 126.5 (2C, aromatic), 127.8 (4C, aromatic), 127.8
(2C, aromatic), 127.9 (4C, aromatic), 130.2 (4C, aromatic),
131.8 (2C, aromatic), 132.3 (4C, aromatic), 132.8 (2C, aro-
matic), 163.0 (1C of Cp), 201.1 (CO). IR (KBr): 2006 (s), 1949
(s) cm-1. MS (MALDI-TOF, matrix: 2,5-dihydroxybenzoic
acid): m/z (M + H)+ calcd for C34H30NO3102Ru 602.13, found
602.1. Isotope pattern for (M + H)+ of 4a : m/z (calcd, obsd)
605 (19, 13), 604 (54, 58), 603 (35, 48), 602 (100, 100), 601 (59,
86), 600 (45, 65), 599 (34, 62). Anal. Calcd for C34H29NO3Ru:
C, 67.99; H, 4.87; N, 2.33. Found: C, 68.17; H, 4.87; N, 2.18.
P r oced u r e B. Isopropylamine (63 µL, 0.73 mmol) was
added to a solution of 5a (209 mg, 0.37 mmol) in toluene (15
Ack n ow led gm en t. The Wisconsin group gratefully
acknowledges financial support from the Department
of Energy, Office of Basic Energy Sciences, and from
the NSF (Grant No. CHE-9629688) and NIH (Grant No.
I S10 RR04981-01) for the purchase of NMR spectrom-
eters and from the NSF for the purchase of a Micromass
LCT mass spectrometer (Grant No. CHE-9974839). The
Stockholm group gratefully acknowledges financial sup-
port from the Swedish Research Council and the Nor-
wegian Research Council (NFR) for a stipend to L.J . The
POSTECH group acknowledges financial support from
KOSEF through the Center of Integrated Molecular
System.
OM020097T