Access to novel ruthenium-amidinate complexes, (η6-arene)Ru(η2-amidinate)X and [Ru(η2-amidinate)(MeCN)4]+PF6 - by photochemical displacement of the benzene ligand in (η6-C6H6)Ru(η2-amidinate)X

Article abstract of DOI:10.1021/om020227y

A study of novel ruthenium-amidinate complexes was carried out by photochemical displacement of benzene ligand. The complex 5 also reacted with pyridine to give a bispyridine complex. The acetonitrile ligands of 5 are easily replaceable by other σ-donor ligands (L) such as pyridines, phosphines, and isocyanides.

Full text of DOI:10.1021/om020227y

3884
Organometallics 2002, 21, 3884-3888
Access to Novel Ru th en iu m -Am id in a te Com p lexes,
(η6-a r en e)Ru (η2-a m id in a te)X a n d
-
[Ru (η2-a m id in a te)(MeCN)4]+P F 6 by P h otoch em ica l
Disp la cem en t of th e Ben zen e Liga n d in
(η6-C6H6)Ru (η2-a m id in a te)X
Taizo Hayashida and Hideo Nagashima*
Graduate School of Engineering Sciences, Institute of Advanced Material Study and CREST,
J apan Science and Technology Corporation (J ST), Kyushu University, Kasuga,
Fukuoka 816-8580, J apan
Received March 26, 2002
Novel ruthenium-amidinate complexes, (η6-C6H5R)Ru(η2-amidinate)X (R ) Me, OMe, F)
(4) and [Ru(η2-amidinate)(MeCN)4]+PF6- (5) are synthesized by photochemical displacement
of the benzene ligand in (η6-C6H6)Ru(η2-amidinate)X (3) by arenes or MeCN. The acetonitrile
ligands of 5 are easily replaceable by other σ-donor ligands (L) such as pyridines, phosphines,
and isocyanides to afford the corresponding derivatives, [Ru(η2-amidinate)(MeCN)n(L)4-n+]-
-
PF6 (n ) 1 or 2).
In tr od u ction
arene,6f or η4-diene ligand.6g In particular, we found that
thermally stable but highly reactive 16-electron com-
plexes Cp*Ru(η-amidinate) (1) and [(η6-arene)Ru(η-
amidinate)]+X- (2) have an unusual bonding mode of
the amidinate ligand, in which π-electrons on the
amidinate ligand mitigate the coordinatively unsatur-
ated nature of the ruthenium center.6a,f The unique
reactivity of these ruthenium amidinates prompted us
to explore the synthesis of organoruthenium amidinates
with novel structures other than 1 and 2.
Photochemical substitution of the arene ligand in (η6-
arene)RuX2(PR3) or [(η6-arene)Ru(η5-C5R5)]+ and their
analogues is an interesting subject in early organome-
tallic photochemistry,7 leading to practical synthetic
methods for several ruthenium complexes.7,8 In particu-
lar, photoirradiation of (η6-benzene)RuX2(PR3) in aro-
matic solvents provides access to (η6-substituted ben-
Amidinates are one of the well-investigated pseudo-
allyl ligands, especially for early transition metals,1,2
and some of them have lately attracted considerable
attention as a substitute of the Cp ligand in metallocene
catalysts for olefin polymerization3 and as a unique
bridging ligand for dinuclear complexes.4 Although a
wide variety of transition metal amidinates have been
reported, organoruthenium complexes having amidinate
ligands are surprisingly rare.5 We have recently re-
ported the preparation and characterization of a series
of organoruthenium amidinates bearing a Cp*,6a-e η6-
(1) (a) Baker, R. Chem. Rev. 1973, 73, 487. (b) 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 255. (c) Oldham, C. Prog. Inorg. Chem. 1968, 10,
223. (d) Mehrotra, R. C.; Bohra, R. Metal Carboxylates; Academic
Press: San Diego, 1983. (e) Keable, H. R.; Kilner, M. J . Chem. Soc.,
Dalton Trans. 1972, 1535.
(2) (a) Barker, J .; Kilner, M. Coord. Chem. Rev. 1994, 133, 219. (b)
Edelmann, F. T. Coord. Chem. Rev. 1994, 137, 403.
(5) (a) Robinson, S. D.; Sahajpal, A. J . Organomet. Chem. 1976, 117,
C111. (b) Brown, L. D.; Robinson, S. D.; Sahajpal, A.; Ibers, J . A. Inorg.
Chem. 1977, 16, 2728. (c) Robinson, S. D.; Sahajpal, A. J . Organomet.
Chem. 1979, 164, C9. (d) Sahajpal, A.; Robinson, S. D. Inorg. Chem.
1979, 18, 3572. (e) Harris, A. D.; Robinson, S. D.; Sahajpal, A.;
Hursthouse, M. B. J . Chem. Soc., Dalton Trans. 1981, 1327. (f) Bear,
J . L.; Han, B.; Huang, S. J . Am. Chem. Soc. 1993, 115, 1175.
(6) (a) Yamaguchi, Y.; Nagashima, H. Organometallics 2000, 19, 725.
(b) Kondo, H.; Yamaguchi, Y. Nagashima, H. Chem. Commun. 2000,
1075. (c) Kondo, H.; Kageyama, A.; Yamaguchi, Y.; Haga, M.; Kirchner,
K.; Nagashima, H. Bull. Chem. Soc. J pn. 2001, 10, 1927. (d) Kondo,
H.; Nagashima, H. J . Am. Chem. Soc. 2001, 123, 500. (e) Kondo, H.;
Matsubara, K.; Nagashima, H. J . Am. Chem. Soc. 2002, 124, 534. (f)
Hayashida, T.; Yamaguchi, Y.; Kirchner, K.; Nagashima, H. Chem.
Lett. 2001, 954. (g) Hayashida, T.; Miyazaki, Y.; Yamaguchi, Y.;
Nagashima, Y. J . Oraganomet. Chem. 2001, 634, 167.
(3) Recent report for early transition metal amidinates for olefin
polymerization. (a) Koterwas, L. A.; Fettinger, J . C.; Sita, L. R.
Organometallics 1999, 18, 4183. (b) Babcock, J . R.; Incarvito, C.;
Rheingold, A. L.; Fettinger, J . C.; Sita, L. R. Organometallics 1999,
18, 5729. (c) J ayaratne, K. C.; Keaton, R. J .; Henningsen, D. A.; Sita,
L. R. J . Am. Chem. Soc. 2000, 122, 10490. (d) Decker, J . M.; Geib, S.
J .; Meyer, T. Y. Organometallics 1999, 18, 4417. (e) Volkis, V.;
Shmulinson, M.; Averbuj, C.; Lisovskii, A.; Edelmann, F. T.; Eisen,
M. S. Organometallics 1998, 17, 3155. (f) Averbuj, C.; Tish, E.; Eisen,
M. S. J . Am. Chem. Soc. 1998, 120, 8640. (g) Averbuj, C.; Eisen, M. S.
J . Am. Chem. Soc. 1999, 121, 8755. (h) Brandsma, M. J . R.; Brussee,
E. A. C.; Meetsma, A.; Hessen, B.: Teuben, J . H. Eur. J . Inorg. Chem.
1998, 1867.
(4) (a) Cotton, F. A.; Daniels, L. M.; Murillo, C. A. Inorg. Chim. Acta
1994, 224, 5. (b) Cotton, F. A.; Daniels, L. M.; Maloney, D. J .; Matonic,
J . H.; Murillo, C. A. Polyhedron 1994, 13, 815. (c) Cotton, F. A.;
Wojtczak, W. A. Polyhedron 1994, 13, 1337. (d) Arnold, D. I.; Cotton,
F. A.; Maloney, D. J .; Matonic, J . H.; Murillo, C. A. Polyhedron 1997,
16, 133. (e) Cotton, F. A.; Daniels, L. M.; Matonic, J . H.; Murillo, C. A.
Inorg. Chim. Acta 1997, 256, 277. (f) Cotton, F. A.; Daniels, L. M.;
Maloney, D. J .; Matonic, J . H.; Murillo, C. A. Inorg. Chim. Acta 1997,
256, 283. (g) Cotton, F. A.; Daniels, L. M.; Feng, X.; Maloney, D. J .;
Matonic, J . H.; Murillo, C. A. Inorg. Chim. Acta 1997, 256, 291. (h)
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16, 1831.
(7) (a) Gill, T. P.; Mann. K. R. Organometallics 1982, 1, 485. (b)
Mann, K. R.; Blough, A. M.; Schrenk, J . L.; Koefod, R. S.; Freedman,
D. A.; Matachek, J . R. Pure Appl. Chem. 1995, 67, 95.
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1974, 233. (b) Graf, D. D.; Mann. K. R. Inorg. Chem. 1997, 36, 150. (c)
Freedman, D. A.; Evju, J . K.; Pomije, M. K.; Mann, K. R. Inorg. Chem.
2001, 40, 5711. (d) Gamble, G.; Grutsch, P. A.; Ferraudi, G.; Kutal C.
Inorg. Chem. Acta 1996, 247, 5. (e) Lavallee, R. J .; Kutal, C. J .
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10.1021/om020227y CCC: $22.00 © 2002 American Chemical Society
Publication on Web 08/16/2002

Novel Ruthenium-Amidinate Complexes
Organometallics, Vol. 21, No. 19, 2002 3885
Ta ble 1. Su bstitu en t Effects on Ar en e
P h otod isp la cem en t Rea ction s of 3 in C6D6
Sch em e 1
a
time/ conversion/ selectivity/
b
b
entry complex
R
R′
X
h
%
%
1
2
3
4
3a
3b
3c
3d
tBu Ph Cl
tBu Ph Br
iPr Ph Cl
iPr Me Cl
1
6
1
5
1
5
1
5
82
>99
71
>99
49
91
78
>99
>99
>99
>99
>99
58
43
98
61
amidinate ligand was observed. The reaction was over
after 5 h, during which no byproduct was observed in
1
the H NMR spectra. In the 13C NMR spectrum of the
product the C6D6 molecule coordinated to the ruthenium
is observed at 81.5 ppm as a triplet (J CD ) 24.5 Hz),
whereas the mass spectrum showing a parent mass
peak at m/e 451 is in accord with the formation of (η6-
C6D6)Ru{η2-tBuNC(Ph)dNtBu}Cl (3a -d 6). Halogen atom
did not affect the rate or the selectivity of the reaction;
photosubstitution of the Br homologue 3b proceeded
without formation of byproducts (Table 1, entry 2). In
contrast, the rate and selectivity were affected by the
substituents of the amidinate ligands; reactions of 3c
and 3d were accompanied by side reactions to give the
corresponding C6D6 complexes in lower yields (Table 1,
entries 3 and 4).
a
Reaction conditions: the C6D6 solution of 3 containing (CHCl2)2
as an internal standard in an NMR tube sealed under 10-3 Torr
atmosphere was irradiated by a Xe lamp through a water filter.
Calculated by 1H NMR spectra.
b
zene)RuX2(PR3),8a whereas that of [(η6-benzene)Ru(η5-
C5R5)]+ in acetonitrile affords [(η5-C5R5)Ru(MeCN)3]+.8b-g
Since acetonitrile ligands in metal complexes are gener-
ally labile for ligand substitution reaction,9 the latter
acetonitrile complexes, [(η5-C5R5)Ru(MeCN)3]+, are use-
ful as attractive precursors for a variety of ruthenium
complexes10 or catalysts in organic synthesis11 by reac-
tions with nitrogen, phosphorus, olefinic, and acetylenic
compounds. This prompted us to examine photoassisted
replacement of the benzene ligand in (η6-C6H6)Ru(η2-
amidinate)X by substituted benzene or MeCN, which
should lead to organoruthenium amidinate with a novel
structure. The reaction actually proceeded smoothly to
result in efficient preparation of (η6-C6H5R)Ru(η2-amidi-
nate)X (R ) Me, OMe, F) (4) and [Ru(η2-amidinate)-
(MeCN)4]+X- [X ) PF6 (5), Cl (5′)]. Furthermore, the
acetonitrile complex 5 is reactive toward various σ-donor
ligands (L), leading to novel organoruthenium amidi-
nates, [Ru(η2-amidinate)(MeCN)n(L)4-n]+X-.
As shown in Scheme 1, the photoirradiation of 3a in
toluene, anisole, and fluorobenzene afforded the corre-
sponding arene complexes (η6-C6H5R)Ru(η2-amidinate)X
{R ) Me (4a ), OMe (4b), F (4c)} in good yield.12
1
Assignment of 4 was performed by H and 13C NMR,
mass spectra, and elemental analyses, and supported
by crystallography of the anisole complex 4b as shown
in Figure 1.16 Either electron-donating anisole or electron-
deficient fluorobenzene reacted with 3a at a similar rate
and with good selectivity.12
P h ot och em ica l Access t o [R u (η2-a m id in a t e)-
(MeCN)4]+X- [X ) P F 6 (5), Cl (5′)]. During the studies
described above, we found that photoirradiation of 3a
in PhCN afforded a complicated mixture of products,
while dissociation of the benzene ligand was observed
in 1H NMR. This can be attributed to coordination of
not only the aromatic ring of PhCN but also its nitrile
moiety to the intermediate of the photochemical sub-
Resu lts a n d Discu ssion
P h otoch em ica l Ar en e Exch a n ge Rea ction s. We
first investigated the photosensitivity of (η6-C6H6)Ru-
(η2-amidinate)X (X ) halogen) (3a -3d ) in C6D6 as
shown in Table 1. Photoirradiation of a C6D6 solution
of 3a -3d by a 500 W Xe lamp at room temperature
resulted in displacement of the C6H6 ligand by a C6D6
molecule, which can be monitored by 1H NMR. For
instance, the signal intensity of the C6H6 ligand at 5.02
ppm on the 1H NMR spectra of 3a gradually diminished
during the photoirradiation, and instead that due to the
free C6H6 appeared. No sign of H-D exchange in the
(12) Only a few examples have been reported on transition metal
complexes bound to fluorobenzenes in the η6-coordination mode. To
our knowledge, fluorobenzene complexes of ruthenium are unknown.
Some examples are seen in chromium chemistry;13 (FC6H5)Cr(CO)3 is
prepared from Cr(CO)6 only in low yields due to the concomitantly
occurring defluorination.14 In the arene exchange reaction of (arene)-
15a
Cr(CO)3
or (arene)Cr(CO)2(SiCl3)2,15b electron-deficient FC6H5 is a
weakly coordinated ligand to the chromium atom, being easily replace-
able by benzene. Thus, successful exchange of coordinated benzene by
fluorobenzene in the present report is not common.
(13) (a) Davis, R.; Kane-Maguire, L. A. P. In Comprehensive Orga-
nometallic Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.;
Pergamon Press: Oxford, U.K., 1982; Vol. 3, Chapter 26.2. (b) Michael,
J . M. In Comprehensive Organometallic Chemistry; Abel, E. W., Stone,
F. G. A., Wilkinson, G., Eds.; Pergamon Press: Oxford, U.K., 1995;
Vol. 5, Chapter 8, and references therein.
(9) (a) See ref 1b, pp 199. (b) Storhoff, B. N.; Lewis, H. C., J r. Coord.
Chem. Rev. 1977, 23, 1.
(10) For
a recent review: Slugovc, C.; Ru¨ba, E.; Schmid, R.;
Kirchner, K.; Mereiter, K. Monatsh. Chem. 2000, 131, 1241.
(14) Milan, H.; Stefan, T. J . Organomet. Chem. 1990, 393, 115.
(15) (a) Christopher, A. L. M.; Peter, L. P. J . Chem. Res. Minipr.
1979, 1754. (b) Balaji, R. J .; Kenneth, J . K. J . Coord. Chem. 1995, 34,
31, and references therein.
(16) Crystal data for 4b: C22H31N2OClRu; M ) 476.01, monoclinic,
a ) 10.1667(6) Å, b ) 17.8999(11) Å, c ) 11.9921(7) Å, â ) 93.309(2)°,
V ) 2178.7(2) Å3, T ) 293 K, space group, Cc (No. 9), Z ) 4, µ(Mo KR)
) 0.856 mm-1, 2489 reflections measured, 2489 unique (Rint ) 0.000),
2053 observed (>2σ), final residuals R1 ) 0.0413, wR2 ) 0.1021 [I >
2σ(I)]; R1 ) 0.0549, wR2 ) 0.1114 (all data).
(11) Recent progress: (a) B. M. Trost, Pinkerton, A. B. Angew.
Chem., Int. Ed. 2000, 39, 360. (b) Trost. B. M.; Machacek. M.;
Schnaderbeck, M. J . Org. Lett. 2000, 2, 1761. (c) Trost, B. M.; Toste,
F. D.; Shen, H. J . Am. Chem. Soc. 2000, 122, 2379. (d) Trost, B. M.;
Brown, R. E.; Toste, F. D. J . Am. Chem. Soc. 2000, 122, 5877. (e) Trost,
B. M.; Pinkerton, A. B. J . Am. Chem. Soc. 2000, 122, 8081. (f) Trost,
B. M.; Pinkerton, A. B.; Kremzow, D. J . Am. Chem. Soc. 2000, 122,
12007. (g) Trost, B. M.; Shen, H. C. Angew. Chem., Int. Ed. 2001, 40,
2313. (h) Trost, B. M.; Rudd, M. T. J . Am. Chem. Soc. 2001, 123, 8862.

3886 Organometallics, Vol. 21, No. 19, 2002
Hayashida and Nagashima
F igu r e 2. ORTEP drawing of 6 with thermal ellipsoids
drawn at the 50% probability level. All hydrogen atoms and
the counteranion are omitted for clarity. Representative
bond distances (Å) and angles (deg) are as follows: Ru1-
N1 ) 2.171(4), Ru1-N2 ) 2.103(4), Ru1-N3 ) 2.088(4),
Ru1-N4 ) 2.114(4); N1-Ru1-N2 ) 61.48(15), N1-C9-
N2 ) 110.6(4).
F igu r e 1. ORTEP drawing of 4b with thermal ellipsoids
drawn at the 50% probability level. All hydrogen atoms are
omitted for clarity. Representative bond distances (Å) and
angles (deg) are as follows: Ru1-Cl1 ) 2.408(2), Ru1-N1
) 2.103(6), Ru1-N2 ) 2.115(10), N1-C16 ) 1.325(10),
N2-C16 ) 1.342(9); N1-Ru1-N2 ) 61.7(3), N1-C16-N2
) 108.5(7), N1-Ru1-Cl1 ) 84.3(2), N2-Ru1-Cl1 )
86.0(3).
Sch em e 3
Sch em e 2
stitution. Coordination of the nitrile to the intermediates
was proved by the result that photoirradiation of 3a in
MeCN afforded the cationic ruthenium-amidinate com-
plex [Ru(η2-tBuNCPhdNtBu)(MeCN)4]+Cl- (5′) in good
yield, as shown in Scheme 2. This complex is highly
unstable in both solid and solution states toward air and
moisture, but could be assigned by NMR spectroscopy.
MeCN ligands are coordinated to the ruthenium at the
trans positions of the N atoms of the amidinate ligand,
and the other two MeCN ligands are bound to the metal
at the axial positions, as illustrated in Scheme 2.
Aceton itr ile Com p lex 5 a s a P r ecu r sor of New
Or ga n or u th en iu m Am id in a tes. As described above,
the acetonitrile ligand is generally reactive toward
ligand substitution. In fact, reaction of 5 with several
two-electron-donor ligands resulted in formation of new
organoruthenium amidinates, as shown in Scheme 3.
Treatment of 5 with bipyridine in acetone afforded
[Ru(η2-amidinate)(MeCN)2(bipy)]+PF6- (6) at room tem-
perature. The structure of 6 was assigned by NMR and
mass spectroscopy and supported by X-ray crystal-
lography. In the 1H and 13C NMR spectra of 6 in
acetone-d6, two MeCN ligands (δH 2.48 ppm, δC 3.2,
-
Anion exchange of 5′ by PF6 gave [Ru(η2-tBuNCPhd
NtBu)(MeCN)4]+PF6 (5), which is stable in MeCN or
-
acetone, but slowly decomposed to give paramagnetic
products in chlorinated solvents. Exposure of the MeCN
or acetone solution of 5 to air caused instant formation
of the paramagnetic complexes.
NMR and mass spectra of 5 suggested similarities in
1
the structure of 5 to that of 5′. For instance, two H
resonances due to the MeCN ligands in acetone-d6 are
seen at 2.57 and 2.67 ppm as singlets in a ratio of 1:1.
The integral values of these signals relative to the
amidinate ligand suggest the existence of four MeCN
ligands, two of them being magnetically equivalent. Two
tBu groups of the amidinate ligand are magnetically
equivalent and observed as a singlet at 1.10 ppm.
Similarly, the 13C NMR spectrum of 5 in acetone-d6
showed the signals due to the MeCN ligands at 3.3 and
3.5 ppm for the methyl carbons and at 123.1 and 124.1
ppm for the nitrile carbons. These results are in accord
with the octahedral geometry of 5, in which of the two
t
123.0 ppm) or two Bu groups of the amidinate were
magnetically equivalent (δH 1.16 ppm, δC 34.3, 54.9
ppm). The molecular structure determined by crystal-
lography is illustrated in Figure 2 and reveals that this
complex has a distorted octahedral structure and that

Novel Ruthenium-Amidinate Complexes
Organometallics, Vol. 21, No. 19, 2002 3887
spectra were recorded on a J EOL Mstation J MS-70 apparatus.
Elemental analyses were performed by the Elemental Analysis
Center, Faculty of Science, Kyushu University. The Xe lamp
of USHIO Inc. (500 W, type 50101AA-A) was used for photo-
reactions of 3.
the bipyridine ligand coordinates at the trans position
of the amidinate ligand.17 The complex 5 also reacted
with pyridine to give a bispyridine complex, [Ru(η2-
-
amidinate)(MeCN)2(py)2]+PF6 (7). The reaction of 5
with PPh3 afforded a monophosphine complex [Ru(η2-
The MeCN derivatives, 5, 6, 7, and 9, are unstable toward
air and moisture due to facile liberation of the MeCN ligands,
and attempted elemental analyses gave unsatisfactory data.
Thus, all of these complexes were characterized by HRMS, and
amidinate)(MeCN)3(PPh3)]+PF6 (8) in good yield. The
-
t
existence of the magnetically inequivalent Bu groups
of the amidinate ligands in the NMR spectrum of 8
suggests that a PPh3 bonds to the ruthenium atom at
the trans position of the nitrogen atoms of amidinate.
Further substitution of the MeCN ligand by PPh3 did
not occur even in the presence of an excess amount of
PPh3 and by application of longer reaction time; this
could be attributed to steric bulkiness of the PPh3
ligand, which prevented the introduction of the second
PPh3. The complex [Ru(η2-amidnate)(MeCN)2(tBuNC)2]+-
1
actual charts of H and 13C NMR spectra of 5, 6, 7, and 9 are
shown in the Supporting Information as the evidence of purity.
NMR Stu d ies on P h otoir r a d ia tion of 3 in C6D6. A dry
C6D6 solution (0.5 mL) of 3 (0.05 mmol) and Cl2CHCHCl2 (ca.
5 µL) was degassed and sealed in a NMR tube under reduced
pressure (10-3 Torr) at -78 °C. The solution was photoirra-
diated by a 500 W Xe lamp through a water filter. The con-
version of 3 and the selectivity of the product were calculated
1
by comparison of the integral values of the H NMR signal of
-
PF6 (9) was also obtained through the reaction of 5
3 or the product with that of Cl2CHCHCl2.
t
with excess BuNC in acetone. The reaction was slower
(η6-C6D6)Ru {η2-tBu NC(P h )dNtBu }Cl (3a -d 6): EI mass
[M+] ) 452; 13C{1H} NMR (150 MHz, C6D6) δ 34.09 (C(CH3)3),
55.78 (C(CH3)3), 81.49 (t, J CD ) 26.4 Hz; C6D6), 126.95 126.97,
128.41, 129.64, 132.06, 139.97 (C6H5), 174.50 (NCN).
Gen er a l P r oced u r e for th e Ar en e Su bstitu tion of 3.
In a Schlenk tube, a solution (5 mL) of 3a (0.024 M) in aromatic
solvents was irradiated by a Xe lamp with stirring for 20 h at
room temperature. After removal of the solvent, the desired
product was obtained as an analytically pure form (yield 60-
99%).
than that with pyridine or bipyridine, and NMR obser-
vation of the initial stage of the reaction showed the
formation of the monosubstituted complex Ru(η2-
amidnate)(MeCN)3(tBuNC)]+PF6- (9′) as an intermedi-
ate. Complex 5 does not react with tmeda, tBuCN,
olefins (vinyl ethyl ether, cyclooctadiene), arenes (ben-
zene, toluene), or acetylenes (dimethylacetylene, pheny-
acetylene, 1,6-heptadiyne) even at higher temperature,
in contrast to the ability of [CpRu(MeCN)3]+ to react
with these compounds.10
(η6-C6H 5Me)R u {η2-t Bu NC(P h )dNt Bu }Cl (4a ): yellow
solids; mp 219 °C (dec). Anal. Calcd for C22H31N2ClRu: C,
57.44; H, 6.79; N, 6.09. Found: C, 57.39; H, 6.78; N, 6.06.
EIMS: [M+] ) 460. 1H NMR (400 MHz, C6D6): δ 1.25 (s, 18H;
C(CH3)3), 2.12 (s, 3H; PhCH3), 4.74 (d, J ) 5.9 Hz, 2H; o-C6H5-
Me), 4.84 (t, J ) 5.3 Hz, 1H; p-C6H5Me), 5.05 (t, J ) 5.6 Hz,
2H; m-C6H5Me), 6.82-7.00 (m, 3H; C6H5), 7.09-7.13 (m, 1H;
C6H5), 7.49 (d, J ) 7.6 Hz, 1H; C6H5). 13C{1H} NMR (150 MHz,
C6D6): δ 19.56 (PhCH3) 34.14 (C(CH3)3), 55.57 (C(CH3)3), 75.97,
81.40, 82.33 98.72 (C6H5Me), 126.90 126.93, 128.35, 129.81,
132.13, 140.07 (C6H5), 174.31 (NCN).
(η6-C6H5OMe)Ru {η2-tBu NC(P h )dNtBu }Cl (4b): brown
solids; mp 206 °C (dec). Anal. Calcd for C22H21ON2ClRu: C,
55.51; H, 6.56; N, 5.88. Found: C, 55.37; H, 6.55; N, 5.78.
EIMS: [M+] ) 476. 1H NMR (600 MHz, C6D6): δ 1.25 (s, 18H;
C(CH3)3), 3.61 (s, 3H; PhOCH3), 4.52 (t, J ) 5.1 Hz, 1H; p-C6H5-
OMe), 4.68 (d, J ) 5.7 Hz, 2H; o-C6H5OMe), 5.20 (t, J ) 5.3
Hz, 2H; m-C6H5OMe), 6.86 (t, J ) 7.8 Hz, 1H; C6H5), 6.89-
6.97 (m, 1H; C6H5), 7.11 (d, J ) 7.1 Hz, 1H; C6H5), 7.49 (d,
J ) 7.3 Hz, 1H; C6H5). 13C{1H} NMR (100 MHz, C6D6): δ 34.01
(C(CH3)3), 55.65, 55.67 (C(CH3)3 and C6H5OCH3), 62.63, 69.63,
85.51, 135.34 (C6H5OCH3), 126.91 126.99, 128.35, 129.74,
132.20, 140.06 (C6H5), 173.89 (NCN).
Con clu sion
As described above, facile access of novel ruthenium-
amidinate complexes, (η6-C6H5R)Ru(η2-amidinate)X (4)
and [Ru(η2-amidinate)(MeCN)4]+X- (5), can be accom-
plished by photochemical displacement of the benzene
ligand in 3 by substituted benzene or MeCN. Besides
the utility of the present reaction as a synthetic method
for these new ruthenium amidinates, high reactivity of
5 toward pyridine, phosphine, and isonitrile ligands
opens the way to synthesize [Ru(η2-amidinate)(MeCN)n-
(L)4-n]+X-. We are currently concentrating on a search
for new reactions and catalytic applications of 5.
Exp er im en ta l Section s
Gen er a l P r oced u r es. Manipulation of air- and moisture-
sensitive organometallic compounds was carried out under a
dry argon atmosphere using standard Schlenk tube techniques
associated with a high-vacuum line. All solvents were distilled
over appropriate drying reagents prior to use (toluene, pen-
tane, Et2O; Ph2CO/Na, C6H5OMe, CH2Cl2; CaH2, C6H5F; P2O5,
acetone; MS4A). Reagents employed in this research were used
without further purification. (η6-C6H6)Ru(η2-amidinate)X were
prepared as described in the literature.6f 1H, 13C, and 31P NMR
spectra were recorded on a J EOL Lambda 600 or a Lambda
400 spectrometer at ambient temperature unless otherwise
(η6-C6H5F )Ru {η2-tBu NC(P h )dNtBu }Cl (4c): yellow solids;
mp 207 (dec). Anal. Calcd for C21H28N2FClRu: C, 54.36; H,
6.08; N, 6.04. Found: C, 54.00; H, 6.06; N, 5.91. EIMS: [M+]
) 464. 1H NMR (400 MHz, C6D6): δ 1.25 (s, 18H; C(CH3)3),
4.43 (td, J HH ) 5.9 Hz, J HF ) 3.9 Hz, 1H; p-C6H5F), 4.87 (dd,
J HH ) 5.9 Hz, J HF ) 2.9 Hz, 2H; o-C6H5Me), 5.14 (td, J HH
)
5.8 Hz, J HF ) 2.9 Hz, 2H; m-C6H5Me), 6.80-6.96 (m, 3H; C6H5),
7.09-7.13 (m, 1H; C6H5), 7.44 (d, J ) 7.6 Hz, 1H; C6H5). 13C-
{1H} NMR (100 MHz, C6D6): δ 34.03 (d; J CF ) 1.2 Hz,
C(CH3)3), 55.71 (C(CH3)3), 65.90 (d; J CF ) 22.3 Hz, C6H5F),
73.24 (C6H5F), 87.76 (d; J CF ) 7.0 Hz, C6H5F), 126.90, 127.10,
128.55, 129.65, 132.07 (C6H5), 137.00 (d; J CF ) 276.8 Hz,
C6H5F), 139.76 (C6H5), 174.82 (NCN).
1
noted. H, 13C, and 31P NMR chemical shifts (δ values) were
given in ppm relative to the solvent signal (1H, 13C) or standard
resonances (31P; H3PO4). IR spectra were recorded on a J ASCO
FT/IR-550 spectrometer. Melting points were measured on a
Yanaco micro melting point apparatus. EI and FAB mass
P r epar ation of [Ru (η2-tBu NC(P h )dNtBu )(MeCN)4]+P F6
-
(17) Crystal data for 6: C29H37N6F6PRu; M ) 715.69, monoclinic,
a ) 9.1744(5) Å, b ) 13.6993(7) Å, c ) 24.8932(17) Å, â ) 94.3965-
(10)°, V ) 2178.7(2) Å3, T ) 293 K, space group, P21/n (No. 14), Z ) 4,
µ(Mo KR) ) 0.620 mm-1, 7047 reflections measured, 7047 unique
(Rint ) 0.000), 4931 observed (>2σ), final residuals R1 ) 0.0553,
wR2 ) 0.1460 [I > 2σ(I)]; R1 ) 0.0874, wR2 ) 0.1671 (all data).
(5). In a Schlenk tube, a MeCN solution (10 mL) of 3a (65 mg,
0.15 mmol) was irradiated by a Xe lamp with stirring for 20 h
at room temperature. Formation of [Ru(η-tBuNC(Ph)dNtBu)-
1
(MeCN)4]+Cl- (5′) was confirmed by NMR. The H NMR data
are listed below. The solution was treated with NaPF6 (25 mg,

3888 Organometallics, Vol. 21, No. 19, 2002
Hayashida and Nagashima
0.15 mmol) and stirred for 1 h. Insoluble inorganic salts were
removed by filtration. After removal of the solvent, the residue
was washed with dry Et2O and dried in vacuo to give 5 (56
mg, 0.087 mmol, 58%) as white solids. Mp: 181 °C (dec).
FABMS: [M+] ) 497 (cationic part of 5). FAB-HRMS: calcd
for C23H35N6Ru, 497.1963; found, 497.1973. 1H NMR (600 MHz,
acetone-d6): δ 0.94 (s, 18H; C(CH3)3), 2.57 (s, 6H; CH3CN),
2.67 (s, 6H; CH3CN), 7.26 (ddd, J ) 8.0, 2.0, 1.5 Hz, 2H; C6H5),
7.28 (dddd, J ) 7.9, 7.3, 1.7, 1.5 Hz, 2H; C6H5), 7.34 (tt, J )
7.3, 2.0 Hz, 1H; C6H5). 13C{1H} NMR (150 MHz, acetone-d6):
δ 3.29, 3.47 (CH3CN), 33.26 (C(CH3)3), 54.77 (C(CH3)3), 123.13,
124.11 (CH3CN), 127.82, 128.83, 130.93, 140.87 (C6H5), 170.47
(NCN).
Ru (η2-tBu NC(P h )dNtBu )(P P h 3)(MeCN)3]+P F 6- (8): yel-
low solids (64% yield); mp 150 °C (dec). FAB-MS: [M+] ) 718
(cationic part of 8). Anal. Calcd for C39H47N5PRu: C, 54.29;
H, 5.49; N, 8.12. Found: C, 53.47; H, 5.39; N, 7.95. FAB-
HRMS: calcd for C39H47N5PRu, 718.2613; found, 718.2623. 1H
NMR (400 MHz, acetone-d6): δ 0.71 (s, 9H; C(CH3)3), 1.13 (s,
9H; C(CH3)3), 1.87 (d, J HP ) 1.0 Hz, 3H; CH3CN), 2.59 (d,
J HP ) 0.5 Hz, 6H; CH3CN), 7.33 (tt, J ) 6.9, 1.7 Hz, 2H; C6H5),
7.37-7.46 (m, 3H; C6H5), 7.47-7.53 (m, 9H; C6H5), 7.59-7.70
(m, 6H; C6H5). 13C NMR (100 MHz, acetone-d6): 2.99 (CH3-
CN), 3.72 (CH3CN), 33.83 (d, J CP ) 1.2 Hz; C(CH3)3), 35.16 (d,
J CP ) 0.8 Hz; C(CH3)3), 53.37 (C(CH3)3), 56.41 (d, J CP ) 2.9
Hz; C(CH3)3), 125.32 (CH3CN), 127, 31 (CH3CN), 127.62 (C6H5),
5′: 1H NMR (600 MHz, CD3CN) δ 0.91 (s, 18H; C(CH3)3),
2.40 (s, 6H; CH3CN), 2.47 (s, 6H; CH3CN), 7.21 (ddd, J ) 6.1,
1.8, 1.4. Hz, 2H; C6H5), 7.26 (tdd, J ) 7.5, 1.8, 1.3 Hz, 2H;
C6H5), 7.35 (tt, J ) 7.4, 1.5 Hz, 1H; C6H5).
128.80 (d; J CP ) 8.7 Hz; C6H5), 129.17 (C6H5), 130.37 (d; J CP
)
2.1; C6H5), 131.88 (C6H5), 135.11 (d, J CP ) 9.9 Hz; C6H5), 135.32
(d, J CP ) 9.9 Hz; C6H5), 135.51 (d, J CP ) 37.9 Hz; C6H5), 141.54
(d, J CP ) 2.5 Hz; C6H5), 175.92 (d, J CP ) 2.5 Hz; NCN). 31P-
{1H} NMR (162 ΜΗz, acetone-d6): δ 50.76 (s; PPh3), 350.54
(quin, J PF ) 708 Hz).
Gen er a l P r oced u r e for th e Liga n d Exch a n ge of 5. In
a Schlenk tube, an acetone solution (0.023 M) of 5 was treated
with the ligand (pyridine, PPh3; 2 equiv to 5, bipy; 1 equiv to
[Ru (η2-t Bu NC(P h )dNt Bu )(t Bu NC)2(MeCN)2]+P F 6 (9):
-
t
5, and BuNC, 5 equiv to 5) at -78 °C. The mixture was then
white solids (88% yield); mp 85 °C (dec). FAB-MS: [M+] ) 581
allowed to warm to room temperature with stirring for 2-10
h. The solvent was removed, and then recrystallization by the
CH2Cl2/pentane solution for 6, 7 or wash with Et2O for 8, 9
gave the desired product in pure form.
(cationic part of 9). FAB-HRMS: calcd for
C29H47N6Ru,
581.2906; found, 581.2914. 1H NMR (600 MHz, acetone-d6):
δ 1.01 (s, 18H; C(CH3)3 of the amidinate), 1.56 (s, 18H; (CH3)3C
of the isocyanide), 2.63 (s, 6H; CH3CN), 7.25-7.40 (m, 5H;
C6H5). 13C NMR (150 MHz, acetone-d6): δ 3.02 (CH3CN), 31.20
(C(CH3)3 of the amidinate), 33.76 (C(CH3)3 of the isocyanide),
54.17, 58.15 (C(CH3)3), 123.83 (CH3CN), 127.88, 129.01, 130.63,
141.33 (C6H5), 173.68 (NCN). IR (KBr): ν 2157, 2112 cm-1
[Ru (η2-tBu NC(P h )dNtBu )(bipy)(MeCN)2]+P F6- (6): black
crystals (95% yield); mp 192 °C (dec). FAB-MS: [M+] ) 571
(cationic part of 6). FAB-HRMS: calcd for
C29H37N6Ru,
517.2123; found, 517.2131. 1H NMR (600 MHz, acetone-d6):
δ 1.16 (s, 18H; C(CH3)3), 2.48 (s, 6H; CH3CN), 7.27-7.35 (m,
5H; C6H5), 7.62 (ddd, J ) 7.3, 5.9, 1.5 Hz, 2H; bipy), 8.07 (dt,
J ) 6.0, 1.3 Hz, 2H; bipy), 8.50 (d, J ) 8.2 Hz, 2H; bipy), 8.69
(d, J ) 5.8 Hz, 2H; bipy). 13C{1H} NMR (150 MHz, acetone-
d6): δ 3.22 (CH3CN), 34.26 (C(CH3)3), 54.87 (C(CH3)3), 123.03
(CH3CN), 123.26, 125.21 (bipy), 127.81, 128.87, 130.95 (C6H5),
136.94 (bipy), 142.08 (C6H5), 157.62, 160.36 (bipy), 170.78
(NCN).
t
(NC). The 13C signal of the isocyanide carbon of BuNC was
not observed.
Ack n ow led gm en t. This work was partially sup-
ported by the J apan Society for the Promotion of Sci-
ence (Grants-in-Aid for Scientific Research 10450343,
13540374, 13029090). Help for X-ray analysis by Dr.
Kouki Matsubara (Kyushu University) is acknowledged.
[Ru (η2-tBu NC(P h )dNtBu )(C5H5N)2(MeCN)2]+P F 6 (7):
-
bright yellow crystals (84% yield); mp 128 °C (dec). FAB-MS:
[M+] ) 573 (cationic part of 7). FAB-HRMS: calcd for C29H39N6-
1
Ru, 573.2280; found, 573.2288. H NMR (600 MHz, acetone-
Su p p or tin g In for m a tion Ava ila ble: 1H and 13C NMR
charts of 5, 6, 7, and 9 and text giving the tables of X-ray
structural data, including data collection parameters, posi-
tional and thermal parameters, and bond lengths and angles
for 4b and 6. This material is available free of charge via the
Internet at http://pubs.acs.org.
d6): δ 0.79 (s, 18H; C(CH3)3), 2.96 (s, 6H; CH3CN), 7.23 (ddd,
J ) 7.5, 5.1, 0.9 Hz, 4H; C5H5N), 7.30-7.34 (m, 2H; C6H5),
7.34-7.38 (m, 3H; C6H5), 7.68 (tt, J ) 7.5, 1.3 Hz, 2H; C5H5N),
9.08 (ddd, J ) 5.1, 1.5, 0.9 Hz, 4H; C5H5N). 13C{1H} NMR (150
MHz, acetone-d6): δ 4.29 (CH3CN), 33.73 (C(CH3)3), 54.98
(C(CH3)3), 124.65 (CH3CN), 125.40 (C6H5N), 127.81, 128.73,
131.35(C6H5), 136.04 (C6H5N), 141.31 (C6H5), 155.1 (C6H5N),
171.13 (NCN).
OM020227Y