Unsymmetrical bis(iminoethyl)pyridine metal complexes with a pendant alkenyl substituent. Part B: Internal olefin coordination To ruthenium

Article abstract of DOI:10.1021/om800727q

A series of unsymmetrically substituted 2,6-bis(iminoethyl)pyridine ligands (5a-d), each bearing a 2,6-diisopropylphenyl group and a linear alkenyl group (allyl to hexenyl) at their pairs of imino nitrogen atoms, was reacted with ruthenium(II) reagents. The reaction of the allyl-substituted system 5a with the reagent [Ru(PPh₃)₃Cl₂] gave the [(K ³N,N',N' -chelate Hgand)(PPh₃)RuCl₂] complex 6a, featuring a pair of cis chloride ligands. In contrast, the reactions of 5b-d with [RuCl₂(p-cymene)]₂ yielded the complexes 7b-d. They each feature a pair of trans chloride ligands and an internally coordinated η ²-CH=CH₂group at the octahedrally coordinated ruthenium center. Treatment of 7c,dM with PMe₃ resulted in a replacement of the internally coordinated π-olefin from ruthenium by the phosphine to yield the complexes 8c,d. The compounds 6a, 7b-d, and 8c,d were characterized by X-ray diffraction.

Full text of DOI:10.1021/om800727q

Organometallics 2008, 27, 6557–6564
6557
Unsymmetrical Bis(iminoethyl)pyridine Metal Complexes with a
Pendant Alkenyl Substituent. Part B: Internal Olefin Coordination
to Ruthenium†
Carolin Wallenhorst, Gerald Kehr, Roland Fro¨hlich,‡ and Gerhard Erker*
Organisch-Chemisches Institut der UniVersita¨t Mu¨nster, Corrensstrasse 40, 48149 Mu¨nster, Germany
ReceiVed July 30, 2008
A series of unsymmetrically substituted 2,6-bis(iminoethyl)pyridine ligands (5a-d), each bearing a
2,6-diisopropylphenyl group and a linear alkenyl group (allyl to hexenyl) at their pairs of imino nitrogen
atoms, was reacted with ruthenium(II) reagents. The reaction of the allyl-substituted system 5a with the
reagent [Ru(PPh3)3Cl2] gave the [(κ3N,N′,N′′-chelate ligand)(PPh3)RuCl2] complex 6a, featuring a pair
of cis chloride ligands. In contrast, the reactions of 5b-d with [RuCl2(p-cymene)]2 yielded the complexes
7b-d. They each feature a pair of trans chloride ligands and an internally coordinated η2-CHdCH2
group at the octahedrally coordinated ruthenium center. Treatment of 7c,d with PMe3 resulted in a
replacement of the internally coordinated π-olefin from ruthenium by the phosphine to yield the complexes
8c,d. The compounds 6a, 7b-d, and 8c,d were characterized by X-ray diffraction.
such systems (e.g., 1, see Scheme 1) bearing an aryl substituent
at one nitrogen and an alkyl or aryl group at the other imino
nitrogen were previously described, for example, by Bianchini
and others.5,6 Some of these systems gave active catalysts for
the oligomerization of ethylene upon activation with methyla-
lumoxane. We have just recently described the preparation of
a series of related “unsymmetrical” 2,6-bis(iminoethyl)pyridine
ligands that carry a combination of the ubiquitous 2,6-diiso-
propylphenyl substituent and a linear alkenyl substituent at their
imino nitrogen atoms. The cobalt and iron complexes (2) of a
series ranging from allyl to n-hexenyl were prepared and
characterized, and their ethene polymerization/oligomerization
Introduction
2,6-Bis(iminoalkyl)pyridine chelate ligand systems have been
of great use in coordination chemistry and catalysis.1 A great
variety of κ3N,N′,N′′ complexes of such tridentate ligands of
many metals throughout the periodic table have been reported
in the literature.2-4 Most often, symmetrically substituted ligand
systems were employed in these studies, often using pairs of
identical aryl substituents bonded to the imine nitrogen atoms.
The corresponding bis-N-2,6-diisopropylphenyl derivatives of
cobalt and especially of iron were shown to be suitable
precursors for the generation of very active homogeneous
Ziegler-Natta olefin polymerization catalysts.
There are fewer reports about complexes of unsymmetrically
substituted 2,6-bis(iminoalkyl)pyridine systems. Examples of
(4) (a) Britovsek, G. J. P.; Bruce, M.; Gibson, V. C.; Kimberley, B. S.;
Maddox, P. J.; Mastroianni, S.; McTavish, S. J.; Redshaw, C.; Solan, G. A.;
Stro¨mberg, S.; White, A. J. P.; Williams, D. J. J. Am. Chem. Soc. 1999,
121, 8728–8740. (b) Smit, T. M.; Tomov, A. K.; Gibson, V. C.; White,
A. J. P.; Williams, D. J. Inorg. Chem. 2004, 43, 6511–6512. (c) Kleigrewe,
N.; Steffen, W.; Blo¨mker, T.; Kehr, G.; Fro¨hlich, R.; Wibbeling, B.; Erker,
G.; Wasilke, J.-C.; Wu, G.; Bazan, G. C. J. Am. Chem. Soc. 2005, 127,
13955–13968. (d) Tsurugi, H.; Matsuo, Y.; Yamagata, T.; Mashima, K.
Organometallics 2004, 23, 2797–2805. (e) Small, B. L.; Carney, M. J.;
Holman, D. M.; O’Rourke, C. E.; Halfen, J. A. Macromolecules 2004, 37,
4375–4386. (f) Carney, M. J.; Robertson, N. J.; Halfen, J. A.; Zakharov,
L. N.; Rheingold, A. L. Organometallics 2004, 23, 6184–6190. (g) Ca´mpora,
* To whom correspondence should be addressed. E-mail: erker@
uni-muenster.de.
† Dedicated to Professor Bernt Krebs on the occasion of his 70th birthday.
‡ X-ray crystal structure analyses.
(1) Reviews (a) Britovsek, G. J. P.; Gibson, V. C.; Wass, D. F. Angew.
Chem. 1999, 111, 448-468; Angew. Chem., Int. Ed. 1999, 38, 428-447.
(b) Ittel, S. D.; Johnson, L. K.; Brookhart, M. Chem. ReV. 2000, 100, 1169–
1203. (c) Gibson, V. C.; Redshaw, G. A.; Solan, G. A. Chem. ReV. 2007,
107, 1745–1776.
´
J.; Naz, A. M.; Palma, P.; Alvarez, E.; Reyes, M. L. Organometallics 2005,
(2) (a) Britovsek, G. J. P.; Gibson, V. C.; Kimberley, B. S.; Maddox,
P. J.; McTavish, S. J.; Solan, G. A.; White, A. J. P.; Williams, D. J. Chem.
Commun. 1998, 849–851. (b) Small, B. L.; Brookhart, M.; Bennett, A. M. A.
J. Am. Chem. Soc. 1998, 120, 4049–4050. See also (c) Kooistra, T. M.;
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Gal, A. W. Angew. Chem. 2001, 113, 4855-4858; Angew. Chem., Int. Ed.
2001, 40, 4719-4722. (d) Gibson, V. C.; Humphries, M. J.; Tellmann, K. P.;
Wass, D. F.; White, A. J. P.; Williams, D. J. Chem. Commun. 2001, 2252–
2253. (e) Britovsek, G. P. J.; Clentsmith, G. K. B.; Gibson, V. C.;
Goodgame, D. M. L.; McTavish, S. J.; Pankhurst, Q. A. Cat. Commun.
2002, 3, 207–211. (f) Knijnenburg, Q.; Hetterscheid, D.; Kooistra, T. M.;
Budzelaar, P. H. M. Eur. J. Inorg. Chem. 2004, 1204–1211. (g) Bart, S. C.;
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(3) (a) Readron, D.; Conan, F.; Gamarotta, S.; Yap, G.; Wang, Q. J. Am.
Chem. Soc. 1999, 121, 9318–9325. (b) Dias, E. L.; Brookhart, M.; White,
P. S. Chem. Commun. 2001, 423–424. (c) Esteruelas, M. A.; Lopez, A. M.;
Mendez, L.; Olivan, M.; Onate, E. Organometallics 2003, 22, 395–406.
(d) Calderazzo, F.; Englert, U.; Pamploni, G.; Santi, R.; Sommazzi, A.;
Zinna, M. Dalton Trans. 2005, 914–922.
24, 4878–4881. (h) Knijnenburg, Q.; Smits, J. M. M.; Budzelaar, P. H. M.
Organometallics 2006, 25, 1036–1046. (i) Hayashi, A.; Okazaki, M.; Ozawa,
F.; Tanaka, R. Organometallics 2007, 26, 5246–5249, and references cited
therein.
(5) (a) Small, B. L.; Brookhart, M. J. Am. Chem. Soc. 1998, 120, 7143–
7144. (b) Small, B. L.; Brookhart, M. Macromolecules 1999, 32, 2120–
2130. (c) Britovsek, G. J. P.; Mastroianni, S.; Solan, G. A.; Baugh, S. P. D.;
Redshaw, C.; Gibson, V. C.; White, A. J. P.; Williams, D. J.; Elsegood,
M. R. J. Chem. Eur. J. 2000, 6, 2221–2231. (d) Bianchini, C.; Mantovani,
G.; Meli, A.; Migliacci, F.; Zanobini, F.; Laschi, F.; Sommazzi, A. Eur.
J. Inorg. Chem. 2003, 1620–1631. (e) Pelascini, F.; Wesolek, M.; Peruch,
F.; Lutz, P. J. Eur. J. Inorg. Chem. 2006, 4309–4316. (f) Bianchini, C.;
Gatteschi, D.; Giambastiani, G.; Rios, I. G.; Ienco, A.; Laschi, F.; Mealli,
C.; Meli, A.; Sorace, L.; Toti, A.; Vizza, F. Organometallics 2007, 26,
726–739. (g) Barbaro, P.; Bianchini, C.; Giambastiani, G.; Rios, I. G.; Meli,
A.; Oberhauser, W.; Segarra, A. M.; Sorace, L.; Toti, A. Organometallics
2007, 26, 4639–4651. (h) Bianchini, C.; Giambastiani, G.; Rios, I. G.; Meli,
A.; Oberhauser, W.; Sorace, L.; Toti, A. Organometallics 2007, 26, 5066–
5078.
(6) Review: Bianchini, C.; Giambastiani, G.; Rios, I. G.; Mantovani,
G.; Meli, A.; Segarra, A. M. Coord. Chem. ReV. 2006, 250, 1391–1418.
10.1021/om800727q CCC: $40.75
2008 American Chemical Society
Publication on Web 11/20/2008

6558 Organometallics, Vol. 27, No. 24, 2008
Wallenhorst et al.
behavior was studied (after MAO activation).7 That study
indicated some involvement of the pendant alkenyl groups in
the polymerization process. In order to gain some insight into
the possible internal coordination behavior of such pendant
alkenyl moieties, we looked for some suitable stable model
systems. It is well-known that the corresponding κ3N,N′,N′′-
bis(iminoalkyl)pyridine complexes of Ru(II), in contrast to their
Fe(II) relatives, are diamagnetic and thus amenable to NMR
characterization.8 Since, for example, the bis[N-(2,4-
diisopropylphenyl)iminoethyl]pyridine-RuCl2 system forms a
stable octahedral ethene complex (3),9,10 it was tempting to
investigate the role the pendant alkenyl substituents could
possibly play in this chemistry. The results of a study using a
series of “unsymmetrical” N-alkenyl-substituted bis-
(iminoethyl)pyridine ruthenium systems is reported in this
account.
to contain a single PPh3 ligand bonded to ruthenium. The double
bond of the allyl substituent is apparently not coordinated to
the metal center, either in the crystal or in solution.
The formation of analogous mono-PPh3 Ru complexes was
not observed, at least not in any appreciable amounts, when
the ligand systems 5b-d, bearing longer alkenyl substituents
at one of their imino nitrogen atoms, were treated with
[Ru(PPh3)3Cl2] in refluxing acetone or dichloromethane. Instead,
we observed the formation of the phosphine-free products 7b-d
(see Scheme 3), which feature an internally coordinated alkenyl
unit. These complexes were actually isolated in pure form from
the closely related reaction of the systems 5b-d with [RuCl2(p-
cymene)]2.12 This reaction proceeded much more cleanly and
required slightly less forcing reaction conditions. The complexes
7b-d were isolated from these reactions in 30-69% yield as
dark purple solids.
Scheme 1
Scheme 3
Results and Discussion
We briefly investigated the stability of the internal η2-alkenyl
coordination toward substitution by the strong PMe3 donor
ligand. Under the applied reaction conditions the butenyl Ru
complex 7b proved to be inert. However, with the complexes
7c,d a slow replacement of the internally coordinated olefinic
unit was observed upon exposure to PMe3. Prolonged treatment
of 7c,d with PMe3 in refluxing toluene (12 h) eventually gave
the monophosphine complexes 8c,d in good yields (∼80%
isolated, see Scheme 3).
Syntheses and Reactions. Our “unsymmetrical” chelate
ligands (5a-d) were prepared by condensation of 4 with a series
of the respective aminoalkenes, as was previously described by
us.7,11 The precursor (4) was selectively synthesized by the
reaction of 2,6-diacetylpyridine with 2,6-diisopropylaniline, as
was recently described by Bianchini et al.5
Scheme 2
Spectroscopic and Structural Characterization of the
Products. The [(chelate ligand)(phosphine)]RuCl2 complexes
6a, and 8c,d were characterized by X-ray diffraction (see Table
1). Complex 6a was shown to feature a distorted-octahedral
coordination geometry at the central Ru atom. The three nitrogen
atoms occupy a set of meridional positions. We note that inside
the κ3N,N′,N′′ coordination the central pyridine N to ruthenium
bond is markedly shorter than the pair of lateral imino nitrogen
to metal linkages. Both of the imino CdN functions feature
typical sp2 carbon to nitrogen double-bond lengths. The allyl
substituent at N24 is rotated away from the central core of the
(9) Dias, E. L.; Brookhart, M.; White, P. S. Organometallics 2000, 19,
4995–5004.
(10) See also: (a) Nishiyama, H.; Itoh, Y.; Matsumoto, H.; Park, S.-B.;
Itoh, K. J. Am. Chem. Soc. 1994, 116, 2223–2224. (b) Caldwell, H.;
Pregosin, P. S. Organometallics 2008, 27, 1591–1595, and references cited
therein.
(11) (a) Lions, F.; Martin, K. V. J. Am. Chem. Soc. 1957, 79, 2733–
2738. (b) Sacconi, L.; Morassi, R.; Midollini, S. J. Chem. Soc. A 1968,
1510–1515. Review: (c) Layer, R. W. Chem. ReV. 1963, 63, 489–510. (d)
Alyea, E. C.; Merrell, P. H. Synth. React. Inorg. Met.-Org. Chem. 1974, 4,
535–544.
We first reacted the allyl-substituted ligand (5a) with
[Ru(PPh3)3Cl2] in dichloromethane at 40 °C. The violet product
6a was isolated in 84% yield. The diamagnetic complex was
characterized by elemental analysis, by spectroscopy, and by
an X-ray crystal structure analysis (see below) and was shown
(7) Wallenhorst, C.; Kehr, G.; Luftmann, H.; Fro¨hlich, R.; Erker, G.
Organometallics 2008, 27, 6547–6556.
(8) C¸ etinkaya, B.; C¸ etinkaya, E.; Brookhart, M.; White, P. S. J. Mol.
Catal. A: Chem. 1999, 142, 101–112.
(12) Bennett, M. A.; Huang, T. N.; Matheson, T. W.; Smith, A. K. Inorg.
Synth. 1982, 74–78.

Bis(iminoethyl)pyridine Systems
Organometallics, Vol. 27, No. 24, 2008 6559
Table 1. Selected Structural Parameters of the Ru Phosphine
Complexes 6a and 8c,da
6a
8c
8d
ligandb
cis-PPh3
1.311(5)
1.926(3)
2.189(3)
2.049(3)
2.331(1)
2.449(1)
2.462(1)
1.295(4)
1.303(4)
156.5(1)
100.9(1)
88.1(1)
trans-PMe3
1.280(5)
1.974(2)
2.139(2)
2.083(2)
2.365(1)
2.410(1)
2.401(1)
1.312(3)
1.302(3)
154.7(1)
179.2(1)
172.3(1)
92.4(1)
trans-PMe3
1.182(7)c
1.992(3)
2.143(2)
2.085(3)
2.372(1)
2.400(1)
2.407(1)
1.312(4)
1.303(4)
154.8(1)
178.4(1)
172.4(1)
87.0(1)
-CHdCH2
Ru-N1
Ru-N9
Ru-N24
Ru-P
Ru-Cl1
Ru-Cl2
C7-N9
C22-N24
N9-Ru-N24
N1-Ru-P
Cl1-Ru-Cl2
N1-Ru-Cl1
C7-N9-C10-C11
C7-N9-C10-C15
169.1(1)
93.5(4)
-87.0(4)
-91.9(3)
87.0(3)
-92.9(3)
86.6(3)
a Bond lengths are given in Å and angles in deg. b Cis and trans
relative to the pyridine nitrogen atom. c Bond artificially shortened due
to librations at the end of the chain.
Figure 2. Molecular structure of the [(chelate ligand)(PMe3)-trans-
Cl2Ru] complex 8c.
Figure 3. Projection of the molecular structure of the internal olefin
Ru complex 7b.
Figure 1. View of the molecular structure of complex 6a.
ligand is placed at a trans coordination site relative to the central
pyridine nitrogen atom.
complex. The bulky bis-2,6-diisopropylphenyl substituent has
its plane oriented normal to the central chelate ligand plane. In
complex 6a the pair of chloride ligands is found to be oriented
cis to each other. Consequently, the bulky PPh3 ligand adopts
a position cis to the chelate ligand nitrogen atoms at ruthenium
(see Figure 1 and Table 1).
All three internal η2-alkenyl Ru complexes 7b-d were
characterized by X-ray diffraction. Complex 7b (see Figure 3
and Table 2) features a distorted-octahedral coordination
geometry. The terminal butenyl CdC double bond occupies a
coordination site trans to the pyridine nitrogen atom. The
carbon-ruthenium bond lengths are found around 2.22 Å. In
complex 7b the Ru to CH2 linkage of the Ru(η2-CHdCH2)
moiety is slightly longer than the internal Ru to CH bond. The
CdC bond length has lengthened considerably upon coordina-
tion to the heavy group 8 metal (see Table 2). The chloride
ligands in complex 7b are trans to each other. Again the Ru-N
bond lengths increase markedly in the order Ru-N1 < Ru-N24
< Ru-N9. The 2,6-diisopropylphenyl ligand plane in complex
7b is oriented normal to the plane of the pyridine chelate ligand.
The conformational arrangement of the NCH2CH2-η2-CHdCH2
tether seems to represent a compromise between the desire of
the olefin π ligand to have the C-C vector oriented in the
meridional plane and the connecting -CH2CH2- linker to attain
optimum staggering.
The PMe3 complexes 8c,d both show structures that are very
similar to each other. Therefore, we will discuss here the
structural features of the example 8c (Figure 2). Structural details
of its congener 8d can be found in Table 1, the Experimental
Section, and the Supporting Information. Complex 8c also
features a distorted-octahedral structure in the crystal form. The
bonding features of the chelate ligand moiety are very similar
to those observed for 6a (see Table 1). Again, the pyridine N
to Ru bond is very short and the CdN to Ru linkages are longer.
The 2,6-diisopropylphenyl substituent plane is normal to the
bis(imino)pyridine ligand plane, and the pentenyl substituent
is found in an extended all-antiperiplanar conformation pointing
toward the outside. In contrast to the case for complex 6a, the
pairs of chloride ligands in the systems 8c,d are both found in
positions trans to each other. Consequently, the PMe3 donor

6560 Organometallics, Vol. 27, No. 24, 2008
Wallenhorst et al.
Table 2. Selected Structural Parameters of Internal Olefin Ru
Complexes 7b-da
7bb
7c
7d
n
2
3
4
-CHdCH2
Ru-CHd
Ru-CH2d
Ru-N1
1.382(8)
2.192(5)
2.230(5)
1.954(45
2.166(4)
2.017(4)
2.399(1)
2.396(1)
1.296(6)
1.293(7)
155.6(2)
154.8(2)
168.8(2)
36.4(2)
1.383(7)
2.236(4)
2.212(4)
1.973(3)
2.131(3)
2.075(3)
2.393(1)
2.408(1)
1.307(4)
1.311(6)
154.9(1)
161.7(2)
162.1(2)
36.2(2)
1.353(5)
2.254(3)
2.209(3)
1.966(2)
2.137(2)
2.088(3)
2.403(1)
2.390(1)
1.293(4)
1.298(4)
153.8(1)
163.3(1)
161.0(1)
35.3(1)
Ru-N9
Ru-N24
Ru-Cl1
Ru-Cl2
C7-N9
C22-N24
N9-Ru-N24
N1-Ru-CH
N1-Ru-CH2
CH-Ru-CH2
C7-N9-C10-C11
C7-N9-C10-C15
93.2(6)
-86.4(6)
-91.4(4)
89.6(4)
88.2(4)
-92.4(4)
Figure 5. View of the conformational arrangement of the secondary
(N(CH2)4-η2-CHdCH2)Ru chelate ring in complex 7d.
a Bond lengths are given in Å and angles in deg. b There are two
molecules per unit cell; data are given for molecule A. In molecule B
C26-C28 is disordered.
Table 3. Selected NMR Data of the Ruthenium Phosphine
Complexes 6a and 8c,da
6a
8c
8d
ligandb
cis-PPh3
38.1
6.06
134.9
10.2
17.6
n.o.
4.93
4.82
trans-PMe3
-9.0
5.85
137.9
10.2
17.1
1.7
5.07
5.00
trans-PMe3
-8.9
5.83
138.9
10.3
17.1
n.o.
5.04
4.97
δ(31P)
δ(1H) (-CHd)
δ(13C) (-CHd)
3J(cis)
3J(trans)
2J(gem)
δ(1H) (dCH2)
δ(13C) (dCH2)
115.8
173.0
175.1
115.7
171.2
173.3
114.9
171.0
173.2
δ(13C) (C(22)dNalk
)
)
δ(13C) (C(7)dNaryl
a in CD2Cl2 solution, with coupling constants in Hz. b Cis and trans
phosphine assignments are relative to the pyridine nitrogen atom.
both the -CHd and the dCH2 carbon atoms to smaller δ values
as compared to those of the uncomplexed olefinic moieties (as
found in their PMe3 substitution products 8). For the example
of the 7c/8c pair we have monitored ∆δ values of 43.5 for the
coordination shift of the -CHd signal and 37.6 ppm for
the dCH2 resonance, respectively (see Tables 3 and 4).13 Also,
the difference in the 13C NMR -CHd and dCH2 shifts becomes
markedly smaller upon coordination (e.g. ∆δ(-CHd/dCH2)
) 24.5 (5c),7 22.2 (8c), 16.3 (7c)). In addition, we monitor a
Figure 4. Molecular structure of complex 7c.
The η2-pentenyl Ru complex 7c shows a very similar core
(see Figure 4 and Table 2). The κ3N,N′,N′′-chelate ligand and
the trans pair of chloride ligands occupy five coordination sites
of the distorted-octahedral framework. The sixth place is taken
by the η2-alkenyl ligand. Again, the CdC bond of the
coordinated olefin is markedly elongated (see Table 2). The
longer trimethylene tether now allows the C-C vector of
the coordinated olefin to lie in the meridional plane of the
molecule. The half-chair-like conformation of the connecting
-CH2CH2CH2- unit has caused a pronounced distinction
between the faces of the central chelate ligand.
The molecular structure of complex 7d is similar (see Figure
5 and Table 2). The overall conformational arrangement of the
(N(CH2)4-η2-CHdCH2)Ru unit resembles a boatlike medium-
sized-ring arrangement. We note that a trend is continued to
have the terminal (η2-alkene) CH2-Ru become increasingly
shorter and, consequently, the internal CH-Ru bond to open
up on going from 7b to 7c to 7d (see Table 2). This seems to
be a structural response to the conformational characteristics
of this secondary chelate ring.
3
3
pronounced decrease of the J(cis) and J(trans) H,H-coupling
constants in the respective 1H NMR spectra arising from internal
olefin coordination to the ruthenium center. It appears that the
complexation does not affect the electronic features of the distal
-C(Me)dN-(2,6-diisopropylphenyl) imino groupstheir 13C
NMR resonances remain practically unchanged. However, the
proximal -C(Me)dN alkenylimino moiety seems to recognize
a change caused by internal alkenyl complexation by responding
with shifting the heterocarbonyl 13C NMR resonances to lower
δ values by ∆δ ≈ 1-5 ppm (see Tables 3 and 4).
The internal alkenyl coordination has introduced a new
element of asymmetry to the chelate complexes. Therefore, the
(13) See for a comparison: (a) Wu, Z.; Jordan, R. F.; Petersen, J. L.
J. Am. Chem. Soc. 1995, 117, 5867–5868. (b) Carpentier, J.-F.; Wu, Z.;
Lee, C. W.; Stro¨mberg, S.; Christopher, J. N.; Jordan, R. F. J. Am. Chem.
Soc. 2000, 122, 7750–7767. (c) Casey, C. P.; Klein, J. F.; Fagan, M. A.
J. Am. Chem. Soc. 2000, 122, 4320–4330. (d) Carpentier, J.-F.; Maryin,
V. P.; Luci, J.; Jordan, R. F. J. Am. Chem. Soc. 2001, 123, 898–909. (e)
Brandow, C. G.; Mendiratta, A.; Bercaw, J. E. Organometallics 2001, 20,
4253–4261. (f) Mart´ınez, G.; Royo, P. Organometallics 2005, 24, 4782–
4787. (g) Stoebenau, E. J., III; Jordan, R. F. J. Am. Chem. Soc. 2006, 128,
8638–8650, and references cited therein.
The complexes seem to adopt similar structures in solution.
This is supported by a variety of characteristic NMR features.
In the η2-alkene complexes 7 the internal π-olefin coordination
has resulted in a marked shift of the 13C NMR resonances of

Bis(iminoethyl)pyridine Systems
Organometallics, Vol. 27, No. 24, 2008 6561
Table 4. Selected NMR Data of the Internal Olefin Ru Complexes
ation for the n-butenyl-substituted complex 7b, which has proven
resistant to replacement of the internal π-alkenyl coordination
by PMe3, even under enforced reaction conditions. The com-
plexes 7c,d form PMe3 substitution products, albeit at elevated
temperatures. Here the conformational situation of the tether
might be slightly less favorable than it is for 7b.
This study has shown that our new ligands 5 seem to have a
tendency to form internal alkene π-complexes with ruthenium,
although this internal coordination appears to follow specific
rules. The (chelate ligand)RuCl2 complexes (6-8), as expected,
did not give active catalysts upon treatment with, for example,
the MAO activator.9 The easy formation of the (π-alkenyl)Ru
systems, however, might be taken as an indication of the alleged
involvement of the pendant alkenyl groups in the respective
iron or cobalt systems at their active catalyst stage, as was
suggested from the special behavior that was observed for the
homogeneous Ziegler-Natta catalyst systems derived from the
reaction of the chelate ligand 5 with FeCl2 and CoCl2,
respectively.7
7b-da
7b
7c
7d
n
2
3
4
δ(1H) (-CHd)
δ(13C) (-CHd)
3J(cis)
6.17
105.8
9.3
14.8
4.54
4.10
77.2
167.9
174.3
5.65
94.4
8.9
13.8
4.34
4.05
78.1
170.0
174.3
5.40
100.2
9.7
13.5
4.35
4.28
82.1
170.0
174.2
3J(trans)b
δ(1H) (dCH2)
δ(13C) (dCH2)
δ(13C) (C(22)dNalk
)
)
δ(13C) (C(7)dNaryl
b
a In CD2Cl2 solution, with coupling constants in Hz. 2J(gem) not
observed.
isopropyl groups of the orthogonally oriented bis-2,6-diisopro-
pylphenyl substituents have become differentiated (cis/trans to
the carbon substituent at the π-alkenyl unit) and their methyl
groups are diastereotopic. Therefore, we observed a set of two
-CHMe2 1H NMR resonances and a total of four isopropyl
methyl groups for each of the complexes 7.
Breaking up the internal π-olefin coordination in the com-
plexes 7 by treatment with PMe3 (to give 8c,d) removes the
inherent element of chirality from the system. The resulting
complexes 8 are achiral in solution, but the perpendicular
arrangement of the 2,6-diisopropylphenyl substituent at the
“right” imino nitrogen atom relative to the pyridine plane leaves
an element of axial prochirality in the complexes 8.14 Conse-
quently, for each of the complexes 8c,d we observe a single 1H
NMR -CHMe2 isopropyl septet and a pair of corresponding
-CH(CH3)2 signals of the adjacent diastereotopic isopropyl
methyl groups (for further details see the Experimental Section
and the Supporting Information, where representative NMR
spectra of these complexes are depicted).
Complex 6a shows spectroscopic behavior different from that
of the systems 8 due to the cis coordination of the PPh3 ligand
relative to the pyridine nitrogen atom.15 This leads to the
observation of two -CHMe2 1H NMR septets and a total of
four -CH(CH3)2 methyl group signals. One of these methyl
1H NMR resonances is found at negative δ values (δ -0.60 in
dichloromethane), probably caused by closing of this substituent
into the anisotropy cone of an adjacent PPh3 phenyl group.
Experimental Section
General Procedures. Reactions with air- and water-sensitive
compounds were carried out under argon using Schlenk-type
glassware or in a glovebox. Solid compounds were collected on
sintered-glass frits and washed with appropriate solvents before
being dried under vacuum. Solvents were dried and distilled under
argon prior to use. The unsymmetrically substituted bis(2,6-
iminoethyl)pyridine ligands 57 and [RuCl2(p-cymene)]2 were
12
prepared analogously as described in the literature. The ruthenium
precursor Ru(PPh3)3Cl2 was used as purchased from commercial
suppliers.
The following instruments were used for physical characterization
of the compounds. Melting points: DSC 2010 TA instruments.
Elemental analyses: Foss-Heraeus CHNO-Rapid. ESI-MS analysis:
Quattro LCZ (Waters Micromass, Manchester, U.K.) equipped with
a nano spray inlet. NMR: Bruker AC 200 P (1H, 200 MHz; 31P, 81
MHz), Varian UNITY plus NMR spectrometer (1H, 600 MHz; 13C,
151 MHz; 31P, 243 MHz). Assignments of the resonances were
supported by 2D experiments.
X-ray Crystal Structure Analyses. Data sets were collected
with a Nonius KappaCCD diffractometer, equipped with a rotating
anode generator. Programs used: data collection COLLECT (Nonius
BV, 1998), data reduction Denzo-SMN (Otwinowski, Z.; Minor,
W. Methods Enzymol. 1997, 276, 307-326), absorption correction
SORTAV (Blessing, R. H. Acta Crystallogr. 1995, A51, 33-37;
Blessing, R. H. J. Appl. Crystallogr. 1997, 30, 421-426) and Denzo
(Otwinowski, Z.; Borek, D.; Majewski, W.; Minor, W. Acta
Crystallogr. 2003, A59, 228-234), structure solution SHELXS-97
(Sheldrick, G. M. Acta Crystallogr. 1990, A46, 467-473), structure
refinement SHELXL-97 (Sheldrick, G. M. Acta Crystallogr. 2008,
A64, 112-122), graphics XP (BrukerAXS, 2000) and SCHAKAL
(E. Keller, Universita¨t Freiburg, 1997).
Preparation of Complex 6a. A solution of the bis(2,6-
iminoethyl)pyridine ligand 5a (1.24 g, 3.43 mmol, 1.1 equiv) and
Ru(PPh3)3Cl2 (3.00 g, 3.13 mmol) in 100 mL of dichloromethane
was stirred overnight and refluxed under argon for 4 h. Subsequently
the volume of the solvent was reduced in vacuo until a purple solid
began to form. The precipitation was completed by addition of 80
mL of pentane, and the solid was collected by filtration, washed
with pentane until the solvent was colorless, and dried in vacuo to
give the purple product (84%, 2.31 g, 2.62 mmol). Slow evaporation
from a saturated chloroform solution gave single crystals of 6a for
the X-ray crystal structure analysis. Mp (DSC): 272 °C dec. MS-
ESI (CHCl3, ES+): m/z 760.5 ([M - Cl])+. Anal. Calcd for
C42H46Cl2N3PRu · CH2Cl2 (880.73): C, 58.64; H, 5.49; N, 4.77.
Found: C, 58.43; H, 5.37; N, 4.65. 1H NMR (d2-dichloromethane,
Conclusions
The unsymmetrically substituted bis(2,6-iminoethyl)pyridine
ligands 5 that bear pendant alkenyl groups with tethers of
varying lengths at one imino nitrogen atom and the bulky
ubiquitous 2,6-diisopropylphenyl substituent at the other readily
form very stable κ3N,N′,N′′-chelate complexes upon treatment
with suitable RuCl2 complex precursors. With the exception of
the allyl-substituted system (5a), where the tether might be too
small, all the other systems seem to favor the formation of
internally coordinated η2-alkenyl RuCl2 complexes (7b-d). A
comparison of the structural parameters of the π-(-CHd
CH2)Ru units of the series of complexes 7b-d reveals some
influence of the lengths of the tether on the structural details.
We see that the Ru to terminal CH2 linkage of the Ru(η2-
CHdCH2) units gets shorter with increasing length of the tether,
while the internal Ru to CH linkage progressively becomes
longer. It seems that we have encountered a specifically
favorable secondary [(NCH2CH2-η2-CHdCH2)Ru] chelate situ-
(14) Eliel, E. L.; Wilen, S. H.; Mander, L. N. Stereochemistry of Organic
Compounds, Wiley-VCH: New York, 1994.
(15) Bianchini, C.; Lee, H. M. Organometallics 2000, 19, 1833–1840.

6562 Organometallics, Vol. 27, No. 24, 2008
Wallenhorst et al.
3
4
600 MHz, 298 K): δ(1H) 8.04 (dd, J ) 7.8 Hz, J ) 1.0 Hz, 1H,
123.5 (C-3py), 122.9 (C-5py), 105.8 (-CHd), 77.2 (dCH2), 65.1
(dNCH2-), 35.8 (dNCH2CH2-), 27.9 (-CHA(CH3)2), 27.7 (-CH-
3-Hpy), 7.77 (t, 3J ) 7.8 Hz, 1H, 4-Hpy), 7.69 (dd, 3J ) 7.8 Hz, 4J
B(CH3)2), 25.7 (-CHA(CH3 CH3 )), 25.5 (-CHB(CH3 CH3 )), 25.3
3
4
A
B
A
B
) 1.0 Hz, 1H, 5-Hpy), 7.46 (dd, J ) 7.8 Hz, J ) 1.4 Hz, 1H,
(-CHA(CH3ACH3 )), 25.1 (-CHB(CH3ACH3 )), 20.1 (-CH3aryl),
17.3 (-CH3alk).
B
B
3-Haryl), 7.30 (t, 3J ) 7.8 Hz, 1H, 4-Haryl), 7.24 (br, 3H, Php), 7.12
3
4
(br, 6H, Pho), 7.02 (br, 6H, Phm), 6.83 (d, J ) 7.8 Hz, J ) 1.4
Hz, 1H, 5-Haryl), 6.06 (dddd, 3J ) 17.6 Hz, 3J ) 10.2 Hz, 3J ) 9.4
Hz, 3J ) 3.5 Hz, 1H, -CHd), 4.93 (dm, 3J ) 10.2 Hz, 1H, dCH2E),
X-ray crystal structure analysis of 7b: formula C25H33Cl2N3Ru,
Mr ) 547.51, black crystal, 0.30 × 0.20 × 0.10 mm, a ) 15.651(1)
Å, b ) 10.898(1) Å, c ) 30.092(1) Å, ꢀ ) 91.90(1)°, V ) 5129.8(6)
Å3, Fcalcd ) 1.418 g cm-3, µ ) 0.836 mm-1, empirical absorption
correction (0.788 e T e 0.921), Z ) 8, monoclinic, space group
P21/c (No. 14), λ ) 0.710 73 Å, T ) 198 K, ω and ꢁ scans, 18 264
reflections collected ((h, (k, (l), (sin θ)/λ ) 0.62 Å-1, 10 141
independent (Rint ) 0.053) and 6661 observed reflections (I g
2σ(I)), 599 refined parameters, R1 ) 0.056, wR2 ) 0.141,
maximum (minimum) residual electron density 1.61 (-0.64) e Å-3
close to the metal centers, two almost identical molecules, one with
disorder in the chain (C26-C27-C28) refined with split positions,
hydrogen atoms calculated and refined as riding atoms.
4.82 (dm, 3J ) 17.6 Hz, 1H, dCH2 ), 4.72 (sept, 3J ) 6.8 Hz, 1H,
Z
-CHB(CH3)2), 4.31 (dm, J ) 13.4 Hz, 1H, dNCH2 -), 2.54 (s,
2
A
3H, -CH3aryl), 2.51 (dd, 2J ) 13.4 Hz, 3J ) 9.4 Hz, 1H,
B
3
dNCH2 -), 2.34 (s, 3H, -CH3alk), 2.09 (sept, J ) 6.8 Hz, 1H,
-CHA(CH3)2), 1.48 (d, 3J ) 6.8 Hz, 3H, -CHB(CH3ACH3 )), 0.93
B
(d, J ) 6.8 Hz, 3H, -CHB(CH3ACH3 )), 0.82 (d, J ) 6.8 Hz,
3
B
3
3H, -CHA(CH3ACH3 )), -0.60 (d, 3J ) 6.8 Hz, 3H, -CHA-
B
(CH3ACH3 )). 13C{1H} NMR (d2-dichloromethane, 150 MHz, 298
B
K): δ(13C) 175.1 (CdNaryl), 173.0 (d, ∑3JP,C + JP,C ) 1.3 Hz,
4
CdNalk), n.o. (Phi), 164.7 (C-6py), 164.5 (d, ∑3JP,C + JP,C ) 1.3
4
Hz, C-2py), 147.4 (C-1aryl), 145.3 (C-2aryl), 140.1 (C-6aryl), 134.9
(-CHd), 129.9 (Php), 128.9 (C-4py), n.o. (Pho), 127.5 (Phm), 127.4
(C-4aryl), 126.3 (C-3py), 125.1 (C-3aryl), 124.7 (C-5aryl), 124.4 (C-
5py), 115.8 (dCH2), 56.7 (dNCH2-), 28.4 (-CHB(CH3)2), 27.9
Preparation of Complex 7c. A solution of the bis(2,6-imino-
ethyl)pyridine ligand 5c (1.39 g, 3.56 mmol, 2 equiv) and [RuCl2(p-
cymene)]2 (1.10 g, 1.78 mmol) in 60 mL of ethanol was refluxed
under argon for 16 h. Subsequently the volume of the solvent was
reduced in vacuo until a purple solid began to form. The
precipitation was completed by addition of 60 mL of pentane and
the solid was collected by filtration, washed with pentane until the
solvent was colorless, and dried in vacuo to give the air-stable
product (69%, 1.49 g, 2.47 mmol). Slow evaporation from a
saturated dichloromethane solution gave single crystals of 7c for
the X-ray crystal structure analysis. Mp (DSC): 288 °C dec. MS-
ESI (MeOH/CHCl3, ES+): m/z 526.1 ([M - Cl])+, 490.2 ([M - 2
Cl])+. Anal. Calcd for C26H35Cl2N3Ru · 0.5CH2Cl2 (604.03): C,
(-CHA(CH3)2), 26.2 (-CHB(CH3ACH3 )), 24.8 (-CHA(CH3
-
B
A
CH3 )), 23.9 (-CHB(CH3ACH3 )), 22.8 (-CHA(CH3ACH3 )), 22.0
(-CH3aryl), 16.8 (-CH3alk). 31P{1H} NMR (d2-dichloromethane, 121
MHz, 298 K): δ(31P) 38.1 (s).
B
B
B
X-ray crystal structure analysis of 6a: formula C42H46-
Cl2N3PRu · CH2Cl2, Mr ) 880.68, red crystal, 0.35 × 0.35 × 0.03
mm, a ) 9.688(1)Å, b ) 11.853(1) Å, c ) 36.224(1) Å, ꢀ )
93.24(1)°, V ) 4153.0(6) Å3, Fcalcd ) 1.409 g cm-3, µ ) 0.707
mm-1, empirical absorption correction (0.790 e T e 0.979), Z )
4, monoclinic, space group P21/n (No. 14), λ ) 0.710 73 Å, T )
198 K, ω and ꢁ scans, 42 153 reflections collected ((h, (k, (l),
(sin θ)/λ ) 0.67 Å-1, 10 013 independent (Rint ) 0.051) and 8176
observed reflections (I g 2σ(I)), 491 refined parameters, R1 )
0.046, wR2 ) 0.135, maximum (minimum) residual electron density
2.30 (-0.82) e Å-3 close to the disordered solvent molecule,
hydrogen atoms calculated and refined as riding atoms.
1
52.69; H, 6.01; N, 6.96. Found: C, 53.38; H, 6.36; N, 6.96. H
NMR (d2-dichloromethane, 600 MHz, 298 K): δ(1H) 7.98 (m, 2H,
3-Hpy, 5-Hpy), 7.89 (m, 1H, 4 Hpy), 7.32 (m, 1H, 4-Haryl), 7.29 (m,
1H, 5-Haryl), 7.25 (m, 1H, 3-Haryl), 5.65 (m, 1H, -CHd), 4.34 (d,
3J ) 13.8 Hz, 1H, dCH2 ), 4.05 (d, J ) 8.9 Hz, 1H, dCH2 ),
Z
3
E
4.02 (dm, 2J ) 13.2 Hz, 1H, dNCH2A-), 3.97 (dm, 2J ) 13.2 Hz,
1H, dNCH2 -), 3.23 (sept, 3J ) 6.6 Hz, 1H, -CHA(CH3)2), 2.96
B
Preparation of Complex 7b. A solution of the bis(2,6-
iminoethyl)pyridine ligand 5b (613 mg, 1.63 mmol, 2 equiv) and
[RuCl2(p-cymene)]2 (503 mg, 0.82 mmol) in 60 mL of ethanol was
refluxed under argon for 16 h. Subsequently the volume of the
solvent was reduced in vacuo until a purple solid began to form.
The precipitation was completed by addition of pentane, and the
solid was collected by filtration, washed with pentane until the
solvent was colorless, and dried in vacuo to give the air-stable
product (61%, 549 mg, 1.00 mmol). Slow evaporation from a
saturated dichloromethane solution gave single crystals of 7b for
the X-ray crystal structure analysis. Mp (DSC): >350 °C. MS-ESI
(MeOH/CHCl3, ES+): m/z 512.3 ([M - Cl])+. Anal. Calcd for
C25H33Cl2N3Ru (547.53): C, 54.84; H, 6.08; N, 7.67. Found: C,
54.81; H, 5.91; N, 7.44. 1H NMR (d2-dichloromethane, 600 MHz,
298 K): δ(1H) 7.92 (dd, 3J ) 7.8 Hz, 4J ) 0.8 Hz, 1H, 3-Hpy), 7.86
(m, 1H, dNCH2CH2CH2A-), 2.94 (sept, 3J ) 6.6 Hz, 1H,
-CHB(CH3)2), 2.93 (s, 3H, -CH3alk), 2.67 (s, 3H, -CH3aryl), 2.26
B
(m, 1H, dNCH2CH2CH2 -), 2.07 (m, 1H, dNCH2CH2A-), 1.95
(m, 1H, dNCH2CH2 -), 1.11 (d, 3J ) 6.6 Hz, 3H, -CHA-
B
(CH3ACH3 )), 0.98 (d, 3J ) 6.6 Hz, 6H, -CHA(CH3ACH3 ),
B
B
-CHB(CH3 CH3 )), 0.93 (d, 3J ) 6.6 Hz, 3H, -CHB(CH3 CH3 )).
13C{1H} NMR (d2-dichloromethane, 150 MHz, 298 K): δ(13C) 174.3
(CdNaryl), 170.0 (CdNalk), 158.0 (C-6py), 157.1 (C-2py), 146.1 (C-
1aryl), 141.3 (C-6aryl), 141.3 (C-2aryl), 132.5 (C-4py), 127.3 (C-4aryl),
125.0 (C-5aryl), 124.6 (C-3aryl), 124.2, 123.5 (C-5py o. C-3py), 94.4
(-CHd), 78.1 (dCH2), 52.3 (dNCH2-), 27.8 (-CHA(CH3)2), 27.7
(-CHB(CH3)2), 26.9 (dNCH2CH2CH2-), 25.9 (dNCH2CH2-),
A
B
A
B
25.6 (-CHA(CH3ACH3 )), 25.6, 25.4 (-CHA(CH3ACH3 ),
B
B
-CHB(CH3ACH3 )), 25.3 (-CHB(CH3ACH3 )), 20.8 (-CH3aryl),
17.2 (-CH3alk).
B
B
(t, J ) 7.8 Hz, 1H, 4-Hpy), 7.80 (dd, J ) 7.8 Hz, J ) 0.8 Hz,
3
3
4
1H, 5-Hpy), 7.29 (m, 1H, 5-Haryl), 7.29 (m, 1H, 4-Haryl), 7.24 (m,
X-ray crystal structure analysis of 7c: formula C26H35-
Cl2N3Ru · 0.5CH2Cl2, Mr ) 604.00, black crystal, 0.60 × 0.40 ×
0.30 mm, a ) 25.836(1) Å, b ) 10.897(1) Å, c ) 19.487(1) Å, ꢀ
) 96.40(1)°, V ) 5452.1(6) Å3, Fcalcd ) 1.472 g cm-3, µ ) 0.889
mm-1, empirical absorption correction (0.618 e T e 0.776), Z )
8, monoclinic, space group C2/c (No. 15), λ ) 0.710 73 Å, T )
198 K, ω and ꢁ scans, 17 326 reflections collected ((h, (k, (l),
(sin θ)/λ ) 0.67 Å-1, 6506 independent (Rint ) 0.036) and 5809
observed reflections (I g 2σ(I)), 309 refined parameters, R1 )
0.054, wR2 ) 0.155, maximum (minimum) residual electron density
1.70 (-2.23) e Å-3 close to the disordered solvent molecule,
hydrogen atoms calculated and refined as riding atoms.
1H, 3-Haryl), 6.17 (m, 1H, -CHd), 4.54 (d, J ) 14.8 Hz, 1H,
3
Z
2
3
dCH2 ), 4.47 (dd, J ) 15.3 Hz, J ) 6.0 Hz, 1H, dNCH2A-),
4.35 (m, 1H, dNCH2 -), 4.10 (d, 3J ) 9.3 Hz, 1H, dCH2 ), 3.41
B
E
(sept, J ) 6.8 Hz, 1H, -CHA(CH3)2), 3.03 (sept, J ) 6.8 Hz,
3
3
1H, -CHB(CH3)2), 2.99 (m, 1H, dNCH2CH2A-), 2.83 (s, 3H,
2
3
3
-CH3alk), 2.61 (s, 3H, -CH3aryl), 2.53 (dq, J ) 12.3 Hz, J ) J
) 6.4 Hz, 1H, dNCH2CH2 -), 1.14 (d, 3J ) 6.8 Hz, 3H,
B
-CHA(CH3 CH3 )), 1.01 (d, 3J ) 6.8 Hz, 3H, -CHA(CH3 CH3 )),
A
B
A
B
0.96 (d, J ) 6.8 Hz, 3H, -CHB(CH3ACH3 )), 0.94 (d, J ) 6.8
3
B
3
Hz, 3H, -CHB(CH3ACH3 )). 13C{1H} NMR (d2-dichloromethane,
B
150 MHz, 298 K): δ(13C) 174.3 (CdNaryl), 167.9 (CdNalk), 160.0
(C-6py), 157.5 (C-2py), 146.1 (C-1aryl), 141.1 (C-6aryl), 140.9 (C-
2aryl), 133.4 (C-4py), 127.0 (C-4aryl), 124.9 (C-5aryl), 124.6 (C-3aryl),
Preparation of Complex 7d. A solution of the bis(2,6-
iminoethyl)pyridine ligand 5d (500 mg, 1.24 mmol, 2 equiv) and

Bis(iminoethyl)pyridine Systems
Organometallics, Vol. 27, No. 24, 2008 6563
7.78 (t, 1H, J ) 7.8 Hz, 4-Hpy), 7.26 (m, 1H, 4-Haryl), 7.18 (m,
3
[RuCl2(p-cymene)]2 (380 mg, 0.62 mmol) in 50 mL of ethanol was
refluxed under argon for 16 h. Subsequently the volume of the
solvent was reduced in vacuo until a purple solid began to form.
The precipitation was completed by addition of 60 mL of pentane,
and the solid was collected by filtration, washed with pentane until
the solvent was colorless, and dried in vacuo to give the air-stable
product (30%, 230 mg, 0.37 mmol). Slow evaporation from a
saturated dichloromethane solution gave single crystals of 7d for
the X-ray crystal structure analysis. Mp (DSC): >350 °C. MS-ESI
(MeOH, ES+): m/z 598.1 ([M + Na])+, 575.6 ([M + H])+, 540.1
2H, 3-Haryl), 5.85 (ddt, J ) 17.1 Hz, J ) 10.2 Hz, J ) 6.7 Hz,
3
3
3
3
4
2
1H, -CHd), 5.07 (dq, J ) 17.1 Hz, J ) J ) 1.7 Hz, 1H,
dCH2 ), 5.00 (dm, 3J ) 10.2 Hz, 1H, dCH2 ), 3.96 (m, 2H,
dNCH2-), 3.08 (sept, 3J ) 6.8 Hz, 2H, -CH(CH3)2), 2.79 (s, 3H,
-CH3alk), 2.52 (s, 3H, -CH3aryl), 2.13 (m, 2H, dNCH2CH2CH2-),
Z
E
3
1.87 (m, 2H, dNCH2CH2-), 1.26 (d, JPH ) 7.9 Hz, 9H, PMe),
1.07 (d, 3J ) 6.8 Hz, 6H, -CH(CH3ACH3 )), 0.92 (d, 3J ) 6.8 Hz,
B
6H, -CH(CH3ACH3 )). 13C{1H} NMR (d2-dichloromethane, 150
B
MHz, 298 K): δ(13C) 173.3 (d, ∑3JP,C + 4JP,C ) 3.2 Hz, CdNaryl),
- - 2
Cl])+, 504.2 ([M Cl])+. Anal. Calcd for
171.2 (d, ∑3JP,C + JP,C ) 2.6 Hz, CdNalk), 160.5 (d, ∑3JP,C
+
4
([M
4JP,C ) 1.3 Hz, C-6py), 158.9 (d, ∑3JP,C + JP,C ) 1.0 Hz, C-2py),
149.6 (C-1aryl), 141.5 (C-2aryl), 137.9 (-CHd), 130.9 (C-4py), 126.9
(C-4aryl), 125.2 (C-3aryl), 123.3 (C-3py), 122.3 (C-5py), 115.7 (dCH2),
60.7 (dNCH2-), 31.9 (dNCH2CH2CH2-), 27.8 (dNCH2CH2-),
4
C27H37Cl2N3Ru · 0.5CH2Cl2 (618.05): C, 53.44; H, 6.20; N, 6.80.
Found: C, 53.97; H, 6.17; N, 6.93. 1H NMR (d2-dichloromethane,
600 MHz, 298 K): δ(1H) 8.01 (d, 3J ) 7.7 Hz, 1H, 3-Hpy), 7.97 (d,
3J ) 7.7 Hz, 1H, 5-Hpy), 7.90 (t, J ) 7.7 Hz, 1H, 4-Hpy), 7.32 (t,
3
3J ) 7.5 Hz, 1H, 4-Haryl), 7.27 (d, J ) 7.5 Hz, 1H, 3-Haryl), 7.25
3
27.6 (-CH(CH3)2), 25.3 (-CH(CH3ACH3 )), 25.1 (-CH(CH3
-
B
A
3
(d, J ) 7.5 Hz, 1H, 5-Haryl), 5.40 (m, 1H, -CHd), 4.52 (m, 1H,
B
1
CH3 )), 20.4 (-CH3aryl), 16.1 (-CH3alk), 15.9 (d, JP,C ) 24.3 Hz,
PMe). 31P{1H} NMR (d2-dichloromethane, 243 MHz, 298 K): δ
(31P) ) -9.0 (s).
dNCH2A-), 4.35 (d, 3J ) 9.7 Hz, 1H, dCH2 ), 4.28 (d, 3J ) 13.5
E
Z
B
3
Hz, 1H, dCH2 ), 4.16 (m, 1H, dNCH2 -), 3.09 (sept, J ) 6.7
Hz, 1H, -CHB(CH3ACH3 )), 3.00 (sept, 3J ) 6.7 Hz, 1H,
B
X-ray crystal structure analysis of 8c: formula C29H44Cl2N3PRu,
M ) 637.61, purple-black crystal, 0.60 × 0.25 × 0.02 mm, a )
15.031(1) Å, b ) 10.724(1) Å, c ) 19.300(1) Å, ꢀ ) 101.05(1)°,
-CHA(CH3ACH3 )), 2.90 (m, 1H, dNCH2CH2CH2CH2A-), 2.89
B
(s, 3H, -CH3alk), 2.80 (m, 1H, dNCH2CH2CH2CH2 -), 2.68 (s,
B
3H, -CH3aryl), 2.17 (m, 1H, dNCH2CH2A-), 1.91 (m, 1H,
V ) 3053.3(4) Å3, Fcalcd ) 1.387 g cm-3, µ ) 0.763 mm-1
,
dNCH2CH2CH2A-), 1.81 (m, 1H, dNCH2CH2CH2 -), 1.72 (m,
B
empirical absorption correction (0.657 e T e 0.985), Z ) 4,
monoclinic, space group P21/c (No. 14), λ ) 0.710 73 Å, T ) 198
K, ω and ꢁ scans, 17 887 reflections collected ((h, (k, (l), (sin
θ)/λ ) 0.67 Å-1, 7264 independent (Rint ) 0.037) and 5762
observed reflections (I g 2σ(I)), 334 refined parameters, R1 )
0.039, wR2 ) 0.073, maximum (minimum) residual electron density
0.42 (-0.54) e Å-3, hydrogen atoms calculated and refined as riding
atoms.
1H, dNCH2CH2 -), 1.08 (d, 3J ) 6.7 Hz, 3H, -CHB(CH3 CH3 )),
B
A
B
3
B
3
1.04 (d, J ) 6.7 Hz, 3H, -CHA(CH3ACH3 )), 0.96 (d, J ) 6.7
Hz, 3H, -CHA(CH3ACH3 )), 0.95 (d, 3J ) 6.7 Hz, 3H,
B
-CHB(CH3 CH3 )). 13C{1H} NMR (d2-dichloromethane, 150 MHz,
298 K): δ(13C) 174.2 (CdNaryl), 170.0 (CdNalk), 158.5 (C-6py),
157.1 (C-2py), 145.7 (C-1aryl), 141.6 (C-2aryl), 141.5 (C-6aryl), 132.1
(C-4py), 127.3 (C-4aryl), 124.8 (C-3aryl), 124.6 (C-5aryl), 124.2 (C-
3py), 123.9 (C-5py), 100.2 (-CHd), 82.1 (dCH2), 59.2 (dNCH2-),
33.1 (dNCH2CH2CH2CH2-), 28.3 (dNCH2CH2CH2-), 28.0
A
B
Preparation of Complex 8d. Complex 7d (150 mg, 0.24 mmol)
was dissolved in 15 mL of toluene, and a 1.0 M solution of
trimethylphosphine in toluene (1.31 mL, 1.31 mmol, 5.4 equiv)
was added in the glovebox. The mixture was refluxed for 4 h,
and the solvent was reduced in vacuo until a violet solid began
to form. The precipitation was completed by addition of 80 mL
of pentane, and the solid was collected by filtration, washed with
pentane until the solvent was colorless, and dried in vacuo to
give the violet product (87%, 136 mg, 0.21 mmol). Slow
evaporation from a saturated dichloromethane solution gave
single crystals of 8d for the X-ray crystal structure analysis.
Mp (DSC): 267 °C. MS-ESI (MeOH/CHCl3, ES+): m/z 616.2
([M - Cl])+. Anal. Calcd for C30H46Cl2N3PRu (651.67): C,
(dNCH2CH2-), 27.8 (-CHA(CH3ACH3 )), 27.6 (-CHB(CH3
-
B
A
CH3 )), 25.8 (-CHA(CH3ACH3 )), 25.4 (-CHA(CH3ACH3 )), 25.4
B
B
B
(-CHB(CH3ACH3 )), 25.3 (-CHB(CH3ACH3 )), 21.1 (-CH3aryl),
17.1 (-CH3alk).
B
B
X-ray crystal structure analysis of 7d: formula C27H37
-
Cl2N3Ru · 0.5CH2Cl2, Mr ) 618.03, black crystal, 0.55 × 0.45 ×
0.06 mm, a ) 25.8516(5) Å, b ) 10.8712(2) Å, c ) 20.0594(3)
Å, ꢀ ) 94.351(1)°, V ) 5621.2(2) Å3, Fcalcd ) 1.461 g cm-3, µ )
0.864 mm-1, empirical absorption correction (0.648 e T e 0.950),
Z ) 8, monoclinic, space group C2/c (No. 15), λ ) 0.710 73 Å, T
) 198 K, ω and ꢁ scans, 17 305 reflections collected ((h, (k,
(l), (sin θ)/λ ) 0.67 Å-1, 6927 independent (Rint ) 0.145) and
5708 observed reflections (I g 2σ(I)), 318 refined parameters, R1
) 0.042, wR2 ) 0.100, maximum (minimum) residual electron
density 1.21 (-0.82) e Å-3 close to the disordered solvent molecule,
hydrogen atoms calculated and refined as riding atoms.
Preparation of Complex 8c. Complex 7c (150 mg, 0.25 mmol)
was dissolved in 15 mL of toluene, and a 1.0 M solution of
trimethylphosphine in toluene (1.35 mL, 1.35 mmol, 5.4 equiv)
was added in the glovebox. The mixture was refluxed for 4 h, and
the crude product was precipitated by addition of 80 mL of pentane
at room temperature. The solid was isolated on a Schlenk frit and
recrystallized from 15 mL of dichloromethane. The precipitation
was completed again by addition of 80 mL of pentane, and the
solid was collected by filtration, washed with pentane until the
solvent was colorless, and dried in vacuo to give the violet product
(72%, 132 mg, 0.18 mmol). Slow evaporation from a saturated
dichloromethane solution gave single crystals of 8c for the X-ray
crystal structure analysis. Mp (DSC): 234 °C. MS-ESI (MeOH/
CHCl3, ES+): m/z 660.6 ([M + Na])+, 602.3 ([M - Cl])+, 490.0
([M - 2 Cl - PMe3])+. Anal. Calcd for C29H44Cl2N3PRu · CH2Cl2
(722.57): C, 49.87; H, 6.42; N, 5.82. Found: C, 50.13; H, 6.87; N,
5.54. 1H NMR (d2-dichloromethane, 600 MHz, 298 K): δ(1H) 7.90
1
55.29; H, 7.12; N, 6.45. Found: C, 54.33; H, 7.01; N, 6.10. H
NMR (d2-dichloromethane, 600 MHz, 298 K): δ(1H) 7.90 (d, 3J
3
) 7.5 Hz, 1H, 3-Hpy), 7.82 (d, J ) 7.5 Hz, 1H, 5-Hpy), 7.78 (t,
3J ) 7.5 Hz, 1H, H-4py), 7.26 (m, 1H, 4-Haryl), 7.18 (m, 2H,
3
3
3
3-Haryl), 5.83 (ddt, J ) 17.1 Hz, J ) 10.3 Hz, J ) 8.4 Hz,
3
Z
3
1H, -CHd), 5.04 (d, J ) 17.1 Hz, 1H, dCH2 ), 4.97 (d, J )
10.3 Hz, 1H, dCH2 ), 3.95 (m, 2H, dNCH2-), 3.08 (sept, 3J )
E
6.8 Hz, 2H, -CH(CH3)2), 2.79 (s, 3H, -CH3alk), 2.53 (s, 3H,
-CH3aryl), 2.11 (m, 2H, dNCH2CH2CH2CH2-), 1.79 (m, 2H,
2
dNCH2CH2-), 1.47 (m, 2H, dNCH2CH2CH2-), 1.27 (d, JP,H
)
7.7 Hz, 9H, PMe), 1.08 (d, 3J
)
6.8 Hz, 6H,
-CH(CH3ACH3 )), 0.92 (d, 3J ) 6.8 Hz, 6H, -CH(CH3ACH3 )).
B
B
13C{1H} NMR (d2-dichloromethane, 150 MHz, 298 K): δ(13C)
173.2 (d, ∑3JP,C + JP,C ) 2.8 Hz, CdNaryl), 171.0 (d, ∑3JP,C
+
4
4JP,C ) 2.6 Hz, CdNalk), 160.4 (C-6py), 158.9 (C-2py), 149.6 (C-
1aryl), 141.5 (C-2aryl), 138.9 (-CHd), 130.8 (C-4py), 126.9 (C-
4aryl), 125.2 (C 3aryl), 123.2 (C-3py), 122.2 (C-5py), 114.9 (dCH2),
61.0 (dNCH2-), 33.8 (dNCH2CH2CH2CH2-), 27.9 (dNCH2-
CH2-), 27.6 (-CH(CH3)2), 27.1 (dNCH2CH2CH2-), 25.3
(-CH(CH3ACH3B)), 25.1 (-CH(CH3ACH3B)), 20.3 (-CH3aryl),
16.2 (-CH3alk), 15.9 (d, JP,C ) 24.0 Hz, PMe). 31P{1H} NMR
1
(dm, J ) 7.8 Hz, 1H, 3-Hpy), 7.82 (dm, J ) 7.8 Hz, 1H, 5-Hpy),
(d2-dichloromethane, 243 MHz, 298 K): δ(31P) -8.9 (s).
3
3

6564 Organometallics, Vol. 27, No. 24, 2008
Wallenhorst et al.
X-ray crystal structure analysis of 8d: formula C30H46Cl2N3PRu,
Mr ) 651.64, black crystal, 0.25 × 0.20 × 0.07 mm, a ) 15.6678(4)
Å, b ) 10.4923(4) Å, c ) 19.8860(6) Å, ꢀ ) 102.581(3)°, V )
3190.6(2) Å3, Fcalcd ) 1.357 g cm-3, µ ) 0.732 mm-1, empirical
absorption correction (0.838 e T e 0.951), Z ) 4, monoclinic,
space group P21/c (No. 14), λ ) 0.710 73 Å, T ) 223 K, ω and ꢁ
scans, 27 672 reflections collected ((h, (k, (l), (sin θ)/λ ) 0.66
Å-1, 7569 independent (Rint ) 0.073) and 4628 observed reflections
(I g 2σ(I)), 343 refined parameters, R1 ) 0.047, wR2 ) 0.111,
Acknowledgment. Financial support from the Deutsche
Forschungsgemeinschaft and the Fonds der Chemischen
Industrie is gratefully acknowledged. We thank the BASF
for a gift of solvents.
Supporting Information Available: Text and figures giving
further experimental and spectroscopic details and CIF files giving
crystallographic data. This material is available free of charge via
the Internet at http://pubs.acs.org.
maximum (minimum) residual electron density 0.58 (-0.85) e Å-3
,
hydrogen atoms calculated and refined as riding atoms.
OM800727Q