Two coordination modes of TCNE in the ruthenium amidinates: The first example providing experimental evidence for κ1-N to η2-C rearrangement

Article abstract of DOI:10.1016/j.jorganchem.2008.12.030

Reactions of Cp^*Ru(κ²-N(R){double bond, long}C(R′)NR) (1a; R = ⁱPr, R′ = Me, 1b; R = ^tBu, R′ = Ph) with TCNE initially give dark green colored intermediary species, which are readily converted to brown colored "

Full text of DOI:10.1016/j.jorganchem.2008.12.030

Journal of Organometallic Chemistry 694 (2009) 795–800
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Note
Two coordination modes of TCNE in the ruthenium amidinates: The first
example providing experimental evidence for
1-N to 2-C rearrangement
j
g
Hideo Kondo b, Takashi Sue b, Akira Kageyama b, Yoshitaka Yamaguchi b, Yusuke Sunada a,
Hideo Nagashima a,b,
*
a Division of Applied Molecular Chemistry and Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
b Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka 816-8580, Japan
a r t i c l e i n f o
a b s t r a c t
Reactions of Cp*Ru(j2-N(R)@C(R0)NR) (1a; R = iPr, R0 = Me, 1b; R = tBu, R0 = Ph) with TCNE initially give
Article history:
dark green colored intermediary species, which are readily converted to brown colored ‘‘
tion complexes, Cp*Ru(j2-N(R)@C(R0)NR)(g2-TCNE) (3a; R = iPr, R0 = Me, 3b; R = tBu, R0 = Ph). These ‘‘g2
C” complexes are characterized by spectroscopy and crystallography. A stable ruthenium amidinate
having a ‘‘j1-N”-coordinated TCNE, Cp*Ru( 2-N(tBu)@C(Mes)NtBu)( 1(N)-TCNE) (2c), is synthesized by
treatment of Cp*Ru( 2-N(tBu)@C(Mes)NtBu) (1c) with TCNE, the structure of which is unequivocally con-
g
2-C” coordina-
Received 27 September 2008
Received in revised form 9 December 2008
Accepted 12 December 2008
Available online 25 December 2008
-
j
j
j
Keywords:
TCNE
Ruthenium amidinate
Rearrangement
firmed by X-ray structure determination and the charge transfer nature is supported by ESR analysis.
Close analogy in IR and UV–Vis spectroscopy of 2c with the dark green colored intermediary species
formed from 1b suggests that this is ‘‘
complex 3b.
j g
1-N” ruthenium amidinate, which is rearranged to the ‘‘ 2-C”
Ó 2008 Elsevier B.V. All rights reserved.
1. Introduction
stepwise auto-isomerization of B to A has never been reported to
our best knowledge.
Tetracyanoethylene (TCNE) is a typical strongly electron-with-
drawing alkene, and exhibits strong affinity to electron-donating
organometallic species [1]. Coordination of TCNE to coordinatively
unsaturated organometallic species often results in formation of
As reported earlier, we have synthesized and characterized iso-
lable 16-electron organoruthenium amidinates, Cp*Ru( 2-amidi-
j
nate) (1) [6,7]. The coordinatively unsaturated nature of 1 results
in facile reaction with TCNE, leading to isolation of Cp*Ru(g2
TCNE)(
2-amidinate) having the ‘‘ 2-C” structure [6]. Interestingly,
-
the corresponding
g
2-TCNE complexes, in which central carbons
j
g
of TCNE are bound to the metal center [1,2]. The electron-with-
drawing property of TCNE leads to donation of d-electrons from
impressive color change of the solution was observed during the
reaction. In a typical example, color of the reaction mixture of
occupied orbitals of metallic species to LUMO of TCNE, giving g2
-
Cp*Ru( 2-N(iPr)@C(Me)NiPr) (1a) and TCNE is dark purple ? dark
j
TCNE complexes (the ‘‘
g
2-C” complex, Chart 1A) with a structure
green ? brown. The dark purple color species corresponds to 1a,
close to ‘‘metallacyclopropane extreme”. In contrast, there have
been several reported examples of the complexes, in which a
N„C moiety of TCNE is coordinated to the metal center to form
whereas the brown is the color of Cp*Ru( 2-TCNE)( 2-N(iPr)@C(-
g j
Me)NiPr) (3a), which was isolated and characterized. The dark
green species formed from 1a is unstable, and has not been charac-
terized yet. In this paper, we wish to report the synthesis of the dark
green colored species with longer lifetime, which was obtained by
j
1-NC(CN)C@CCN)2 compounds [3,4]. Since TCNE is a strong elec-
tron acceptor, these formed
‘‘
1-N” complex, Chart 1B) are normally charge-transfer species,
in which a cation radical is located on the metal center, whereas
an anion radical exists on a carbon of the ‘‘
1-N” TCNE ligand.
j
1-NC(CN)C@C(CN)2 compounds (the
j
the reaction of two derivatives of Cp*Ru( 2-N(tBu)@C(R)NtBu)
j
(1b; R = Ph, 1c; R = mesityl) with TCNE. The results suggest that
j
charge transfer ‘‘j1-N isomer” of Cp*Ru( 2-amidinate) is
j-TCNE)(j
Two metallic species, A and B, are structural isomers, and there
is a possible interconversion pathway between A and B. In fact,
there are some examples of the electron-transfer-, photo-, or
thermally-induced isomerization from A to B [5]. However, the
involved in the reaction of 1a with TCNE to form 3a with the ‘‘g2
-
C” coordination mode.
2. Results and discussion
* Corresponding author. Address: Division of Applied Molecular Chemistry and
Institute for Materials Chemistry and Engineering, Kyushu University, Kasuga,
Fukuoka 816-8580, Japan.
We previously became aware that treatment of a coordinatively
unsaturated 16e ruthenium amidinate, Cp*Ru( 2-N(iPr)@C(Me)-
NiPr) (1a), with 1 equiv. of TCNE gives a dark green species, which
j
E-mail address: nagasima@cm.kyushu-u.ac.jp (H. Nagashima).
0022-328X/$ - see front matter Ó 2008 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2008.12.030

796
H. Kondo et al. / Journal of Organometallic Chemistry 694 (2009) 795–800
the N(1)–Ru–N(2) plane and the N(1)–C(11)–N(2) plane (Fig. 3) is
N
N
N
N
N
M
21.5°, which is much more acute compared with that of the (cen-
tral)C–Ph analogue 1b (48.9°). The bond length of Ru–C(1) in 1c
(2.422(3) Å) is ca. 0.1 Å longer than that in complex 1b (2.336 Å).
This significantly small dihedral angle d and lengthening of the
Ru–C(1) bond are caused by steric repulsion between the methyl
groups of the Cp* ligand and an ortho-methyl moiety of the mesityl
group, which provides a smaller coordination sphere around the
ruthenium center than that of the other ruthenium amidinates,
1a and 1b. 1H and 13C NMR spectrum of 1c showed two signals at
dH = 2.20 and 2.21 (singlet) with an integral ratio of 3:6 and
dC = 21.1 and 22.7 ppm, which are assignable to para- and ortho-
methyl moieties of the mesityl group, respectively. On the basis
of the crystal structure, the two ortho methyl signals should be
magnetically inequivalent; however, the dynamic process shown
in Scheme 2 was not frozen to give a single peak (singlet) which
is derived from the o-mesityl group even at ꢀ90 °C. Methyl signals
N
M
N
N
A
B
"η2-C" complex
"κ1-N" complex
Chart 1.
is converted to brown Cp*Ru(
within one minute. Elaboration to capture a dark green species
j g
2-iPrN@C(Me)NiPr)( 2-TCNE) (3a)
with longer life time resulted in discovery that Cp*Ru(j2
-
N(tBu)@C(Ph)NtBu) (1b) reacted with TCNE to give a dark green
species stable in a solution for ca. 1 h. The color of the solution
gradually turned brown, and after 6 h, brown colored Cp*Ru(j2
-
N(tBu)@C(Me)NtBu)(
acterization of two ‘‘
g
g
2-TCNE) (3b) was formed exclusively. Char-
2-C” isomers, 3a and 3b, was carried out by
t
due to the Bu and Cp* moiety appeared at 1.16 and 1.69 ppm,
respectively, in the integral ratio of 18:15.
spectroscopic methods as well as determination of the X-ray struc-
ture of 3a. Typically, a 13C resonance due to the olefinic carbon of
TCNE appeared at d 20.7 (3a) and d 18.8 for (3b), respectively,
which are significantly shifted to upfield compared with the unco-
ordinated TCNE (d 80.3). IR absorptions of mC„N appeared around
2226, 2209 cmꢀ1 for 3a and 2229, 2211 cmꢀ1 for 3b, which are
shifted to a lower wavenumber than those of the uncoordinated
TCNE (2262, 2228, 2214 cmꢀ1) [8]. The X-ray diffraction analysis
of 3a revealed that the ruthenium center adopts the three-legged
piano-stool structure with two nitrogen atoms of amidinate ligand
and the center of the C@C bond of TCNE [6]. It is noteworthy that
significant elongation of the carbon–carbon bond length was ob-
served [3a: C@C 1.499(6) Å; uncoordinated TCNE: C@C
1.344(3) Å] [8], which strongly suggests that the coordination
mode of TCNE is ‘‘metallacyclopropane extreme”, and the formal
oxidation state of the ruthenium center is Ru(IV). The dark green
colored intermediary species was monitored by UV–Vis spectra
of the reaction of 1b with TCNE in THF, which showed absorptions
Treatment of 1c with TCNE resulted in instant color change
from dark purple to dark green as seen in the reaction of 1b with
TCNE, however, the solution remained a dark green color even after
24 h (Scheme 3). From this solution, a product having the ‘‘
structure, Cp*Ru( 2-N(tBu)@C(Mes)NtBu)( 1(N)-TCNE) (2c) was
isolated as dark green crystals in 94% yield.
j
1-N”
j
j
The molecular structure of 2c was determined by crystallogra-
phy. The ORTEP drawing (Fig. 4) revealed that the ligand arrange-
ment around the ruthenium has a coordinatively saturated three-
legged piano-stool structure. As shown in the supporting informa-
tion, TCNE moiety is rotationally disordered with the occupancy of
0.7 and 0.3, and one of the TCNE moieties is depicted in Fig. 4. The
angle h of 142.85 (5)° is in the normal range of h of known coord-
inatively saturated ruthenium amidinates [6,7c,7h]. The UV spec-
trum of 2c is similar to that of an intermediary species 2b
observed in the reaction of 1b with TCNE, giving two absorptions
at 632
(e ) and 850 (e ) nm
= 698 Mꢀ1 cmꢀ1 = 627 Mꢀ1 cmꢀ1
(Fig. 5). IR spectrum of 2c is also similar to that of 2b, giving three
mCN absorptions at 2215, 2192, and 2110 cmꢀ1.The complex 2c is
diamagnetic [10], and 1H and 13C NMR spectrum of 2c show two
signals at dH = 1.86 and 2.50 (singlet), and dC = 20.9 and
25.4 ppm, which are assignable to two inequivalent ortho-methyl
moieties of the mesityl group. Unfortunately, the signals derived
from the C„N and central C–C moieties were not detected due
to the low solubility of 2c. The charge transfer nature of 2c is evi-
denced by ESR signals at g = 2.00021 with the 14N coupling, which
can be interpreted as the oxidation state of ruthenium being III and
location of an anion radical on a carbon of the TCNE ligand.
All of these results strongly suggest that coordination of the
TCNE to the coordinatively unsaturated 16e Ru(II) amidinates pro-
ceeded stepwise; a C„N group of TCNE is bonded to the ruthenium
at 635–641 (e e
= 698 Mꢀ1 cmꢀ1) and 831 ( = 627 Mꢀ1 cmꢀ1) nm
and are characteristic of charge-transfer complexes [4g,5a,5c].
Fig. 1 shows time-dependent UV–Vis spectral changes for forma-
tion of 3b, indicating the presence of the intermediary dark green1
complex 2b during the reaction (vide infra). IR spectrum of the inter-
mediary species showed three mCN absorptions at 2195, 2154, and
2116 cmꢀ1, suggesting the unsymmetrical coordination of TCNE to
the metal center, which is often seen in the charge transfer metal
complexes of TCNE [3,4,8].
Elaboration to isolate the dark green colored species as a stable
form was successful, when the mesityl group was introduced to the
central carbon of the amidinate ligand. The ruthenium amidinate,
Cp*Ru( 2-N(tBu)@C(Mes)NtBu) (1c), was synthesized in 98% yield
j
as dark purple crystals by treatment of [Cp*RuCl]4 with 0.25 equiv.
of Li(N(tBu)@C(Mes)NtBu) in THF at 60 °C for 4 h (Scheme 1). The
product 1c was unequivocally characterized by X-ray diffraction
analysis, NMR spectroscopy, and elemental analysis. The molecular
structure of 1c was established by X-ray study and Fig. 2 shows the
ORTEP view of 1c, the selected bond distances and angles of 1c are
listed in Table 1. The crystallographic data is listed in Table 2. The
Ru atom adopts the two-legged piano-stool structure which is often
seen in the molecular structure of the coordinatively unsaturated
16e Ru mononuclear species [9]. The angle h (177.98(3)°) of 1c
which is defined in Fig. 3 is close to 180°, which is typically seen
in the coordinatively uncoordinated ruthenium amidinate [7d].
The amidinate ligand is bent, and the dihedral angle d defined by
center with a j j
1-NCC(CN)@C(CN)2 mode (the ‘‘ 1-N” isomer); the
coordination accompanied by transfer of an electron from the
Ru(II) center to the TCNE ligand, giving Ru(III) and TCNEꢀꢀ. The
transfer of another electron from the Ru(III) center to the coordi-
nated TCNEꢀꢀ results in isomerization from the ‘‘
j
1-N” isomer to
2-C” isomer). The rear-
1-N” isomer to the ‘‘ 2-C” isomer may in-
volve dissociation and recoordination of TCNE. The ‘‘
2-C” isomer
Cp*Ru(
rangement from the ‘‘
g j g
2-TCNE)( 2-amidinate) (the ‘‘
j
g
g
has a structure close to ruthenacyclopropane extreme, of which
formal oxidation state is Ru(IV). A key experimental result to sup-
port this mechanism is isolation of 2c with the ‘‘
which spectroscopic features (UV, IR) are similar to those of 2b.
Although 2c did not isomerize to the ‘‘
2-C” isomer, the ‘‘ 1-N” iso-
mer of 2b is not very stable and slowly converted to the corre-
sponding ‘‘
2-C” isomer. It is dependent on the steric
circumstances around the ruthenium center how easy the isomer-
j
1-N” structure, of
g
j
1
g
For interpretation of color in Fig. 1, the reader is referred to the web version of
this article.

H. Kondo et al. / Journal of Organometallic Chemistry 694 (2009) 795–800
797
Fig. 1. Time-dependent UV–Vis spectral changes for 1b ? 2b ? 3b.
Table 1
Representative bond lengths and angles for 1c and 2c.
Ru
N
N
1c
2c
N
+
N
[Cp*RuCl]4
0.25
Li
THF, 60 o
4 hrs
C
Bond lengths (Å)
Ru–N(1)
Ru–N(2)
2.101(3)
2.084(3)
2.422(3)
2.078(4)
2.104(3)
–
Ru–C(1)
1c, purple crystals, 98 % yield
Bond angles (°)
N(1)–Ru–N(2)
Ru–N(1)–C(1)
Ru–N(2)–C(1)
N(1)–C(1)–N(2)
63.00(14)
87.1(2)
86.9(2)
62.2(2)
81.73(6)
95.5(3)
107.6(4)
Scheme 1.
110.3(3)
θ
Ru
N
C
δ
Fig. 3. Definition of the angle h and d.
Ru
Ru
Ru
N
tBu
tBu
tBu
tBu N N tBu
N
N
N
Mes
Mes
tBu
Mes
Fig. 2. The molecular structure of 1c with 50% probability ellipsoids. The hydrogen
atoms were omitted for clarity.
Scheme 2.

798
H. Kondo et al. / Journal of Organometallic Chemistry 694 (2009) 795–800
N
R
R
NC
Ru
Ru
NC
Ru
R'
N
TCNE
N
N
CN
R
N
N
R
N
N
N
N
CN
R
R
R'
R'
Ru(IV)
Ru(II)
Ru(III)
R = iPr, R' = Me (1a)
R = tBu, R' = Ph (1b)
R = tBu, R' = Mes (1c)
R = Pr, R' = Me (3a)
i
t
t
i
R = Pr, R' = Me (2a)
R = ttBu, R' = Ph (2b)
R = Bu, R' = Mes (2c)
R = Bu, R' = Ph (3b)
R = Bu, R' = Mes (3c)*
*: not observed
Scheme 3.
Table 2
Crystallographic data for 1c and 2c.
1c
2c
Empirical formula
Formula weight
Crystal system
Lattice type
Space group
a (Å)
C28H44N2Ru
509.74
Triclinic
C41H49N6Ru
726.95
Monoclinic
C-centered
C2/c (#15)
34.150(14)
11.857(4)
19.085(8)
90
100.4000(9)
90
6576(3)
Primitive
ꢀ
P1 (#2)
10.7937(10)
13.3321(13)
9.6704(9)
104.141(5)
91.762(3)
80.126(4)
1329.3(2)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
Volume (Å3)
Z value
8
Dcalc (g/cm3)
1.273
1.295
F(000)
540.00
3048.00
Crystal color, habit
Crystal dimensions, mm
Number of observations
(all reflections)
Dark purple, platelet
0.20 ꢁ 0.15 ꢁ 0.10
5781
Dark green, platelet
0.19 ꢁ 0.12 ꢁ 0.03
8527
Number of variables
Reflection/parameter ratio
R (all reflections)
324
474
17.84
0.0607
0.0578
0.2182
0.999
0.000
1.66
17.99
0.1118
0.0856
0.2666
1.000
0.000
4.52
Fig. 4. The molecular structure of 2c with 50% probability ellipsoids. The hydrogen
atoms were omitted for clarity.
R1(I > 2r
(I))a
wR2 (all reflections)b
Goodness-of-fit
Maximum shift/error in final cycle
Maximum peak in final difference
Map, e-/Å3
knowledge, there is no precedent for the stepwise coordination
of TCNE to the metal center involving the ‘‘j g
1-N” to ‘‘ 2-C” rear-
Minimum peak in final difference
ꢀ1.78
ꢀ1.72
Map, e-/Å3
rangement, which has been unequivocally proven by crystallogra-
phy and spectroscopy. The results provide fresh insight to the
chemistry of a strong electron acceptor coordinating to the elec-
tron rich metal center.
a
R1
=
R
|F0| ꢀ |Fc|/
R|F0|.
h
i
1=2
P
P
2
2
ðwðF20 ꢀ Fc2Þ Þ= ðwðF20Þ Þ
.
b
wR2
¼
4. Experimental
ization is from the ‘‘j g
1-N” isomer to the ‘‘ 2-C” isomer. The small-
t
est d of 1c as well as steric demands of Bu groups and methyl
4.1. General
groups of the mesityl group and the Cp* ligand does not supply
enough space for the
smaller N„C group in TCNE can be bonded to the ruthenium cen-
ter in an
1(N)-fashion.
g
2(C)-coordination of TCNE; however, the
The 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, ether, THF, hexane; Ph2CO/Na). 1H and 13C
NMR spectra were recorded on a JEOL Lambda 600 or a Lambda
400 spectrometer at ambient temperature unless otherwise noted.
1H and 13C NMR chemical shifts (d values) were given in ppm rel-
ative to the solvent signal. IR spectra were recorded on a JASCO FT/
IR-550 spectrometer. Melting points were measured on a Yanaco
micro melting point apparatus. ESR spectrum was recorded on a
JES-FA200 apparatus. Elemental analyses were performed by a Per-
kin Elmer 2400/CHN analyzer. Starting material, [Cp*RuCl]4 was
synthesized by the method reported in the literature [11].
g
3. Conclusion
The coordination behavior of TCNE to an electron rich metal
center has been actively investigated, and there are many exam-
ples of ‘‘g j
2-C” complexes and several charge transfer ‘‘ 1-N” com-
pounds which are independently characterized. In the present
paper, we have reported a reaction pathway involving one electron
transfer from Ru(II) to TCNE to form the ‘‘
Ru(III) and TCNEꢀꢀ moieties, which then isomerized to the ‘‘
isomer having a ruthena(IV)cyclopropane structure. To our best
j
1-N” isomer having
2-C”
g

H. Kondo et al. / Journal of Organometallic Chemistry 694 (2009) 795–800
799
Fig. 5. UV–Vis spetra of the 1c, 2b, 2c, and 3b.
4.2. Preparation of Cp*Ru(
j
2-tBuN@C(Mes)NtBu) (1c)
166.7(NCN). IR (KBr): mC„N (cmꢀ1) = 2215, 2192, 2110 (s). UV–
Vis (THF; kmax, nm;
, Mꢀ1 cmꢀ1): 632 (914), 850 (970). Anal. Calc.
e
To a suspension of [Cp*RuCl]4 (174 mg, 0.16 mmol) in THF
(15 mL) was added a solution of 4 equiv. of Li(tBuN@C(Mes)NtBu)
(180 mg, 0.64 mmol), the mixture was stirred at 60 °C for 4 h,
and the resulting solution was concentrated in vacuo. The obtained
dark purple residue was extracted with pentane twice
(total 10 mL). The extracts were concentrated in vacuo until the
volume of the solution reached ca. 2 mL. The solution was kept
at ꢀ30 °C overnight to give 1c as dark purple crystals in 98%
yield (319 mg). M.p. 122 °C (dec). 1H NMR (600 MHz, THF-d8,
for C34H44N6Ru: C, 64.02; H, 6.95; N, 13.17. Found: C, 63.76; H,
6.88; N, 13.08%.
4.4. Reaction of Cp*Ru( 2-tBuN@C(Ph)NtBu) (1b) with TCNE to form
j
3b
In a 50 mL Schlenk tube were placed complex 1 (48 mg,
0.1 mmol) and TCNE (13 mg, 0.1 mmol) in THF (10 mL). The result-
ing solution was stirred for 6 h at r.t., during which the initial dark
purple solution first turned dark green, then dark brown. The solu-
tion was filtered through a pad of celite, then the solvent was re-
moved in vacuo. The remaining dark brown solid was dissolved
in toluene (20 mL). The solution was concentrated to the volume
of 2–3 mL, and cooled at ꢀ30 °C. Dark brown crystals of 3b were
obtained in 89% yield (54 mg). M.p. 147 °C (dec). 1H NMR
t
r.t.): d 1.16 (s, 18H, CH3 of Bu), 1.69 (s, 15H, CH3 of Cp*), 2.20 (s,
3H, p-CH3 of mesityl), 2.21 (s, 6H, o-CH3 of mesityl), 2.36 (s, 6H,
CH3 of xylyl), 6.75 (s, 2H, Ph). 13C{1H} NMR (150 MHz, THF-d8,
r.t.): d 12.4 (s, C5(CH3)5), 21.1 (s, p-CH3 of mesityl), 22.7 (s, o-CH3
of mesityl), 32.1 (s, C(CH3)3), 54.5 (s, C(CH3)3), 71.4 (s, C5(CH3)5),
128.3, 128.6, 135.6, 138.2 (Ph), 158.9(NCN). UV–Vis (THF;
t
kmax
,
nm;
e
,
Mꢀ1 cmꢀ1): 519
-
529 (1310). Anal. Calc. for
(600 MHz, THF-d8, r.t.): d 1.13 (s, 18H, CH3 of Bu), 1.87 (s, 15H,
C28H44N2Ru: C, 65.96; H, 8.70; N, 5.50. Found: C, 65.70; H, 8.70;
N, 5.44%.
CH3 of Cp*), 7.28–7.36 (m, 3H, Ph), 7.33–7.45 (m, 1H, Ph), 7.62–
7.68 (m, 1H, Ph). 13C{1H} NMR (150 MHz, THF-d8, r.t.): d 10.5(s,
C5(CH3)5), 18.8 (CCN), 35.6 (s, C(CH3)3), 58.5 (s, C(CH3)3), 105.9 (s,
C5(CH3)5), 119.3, 120.6 (CC„N), 127.9, 128.2, 130.7, 131.3, 134.2,
140.6 (Ph), 179.8 (NCN). IR (KBr): mC„N (cmꢀ1) = 2229 (s), 2211
4.3. Preparation of Cp*Ru( 2-tBuN@C(Mes)NtBu)( 1(N)-TCNE) (2c)
j j
In a 50 mL Schlenk tube were placed complex 1 (53 mg,
0.1 mmol) and TCNE (13 mg, 0.1 mmol) in THF (10 mL). The
resulting solution was stirred for 4 h at r.t., during which the ini-
tial dark purple solution turned dark green. The mixture was fil-
tered through a pad of celite, then volatiles were removed in
vacuo. The remaining dark green solid was dissolved in toluene
(20 mL). The solution was concentrated to the volume of 2–
3 mL, and cooled at ꢀ30 °C. Dark green crystals of 2a were ob-
tained in 94% yield (62 mg). M.p. 199 °C (dec). 1H NMR
(s). UV–Vis (THF; kmax, nm; e
, Mꢀ1 cmꢀ1): 635–641 (698), 831
(627). Anal. Calc. for C31H38N6Ru: C, 62.50; H, 6.49; N, 14.11.
Found: C, 62.44; H, 6.35; N, 14.20%.
4.5. X-ray data collection and reduction
X-ray crystallography was performed on a Rigaku Saturn CCD
area detector in the case of 1c, and on a Rigaku RAXIS RAPID
imaging plate diffraction meter in the case of 2c with graphite
t
(600 MHz, THF-d8, r.t.): d 0.68 (s, 18H, CH3 of Bu), 1.87 (s, 15H,
monochromated Mo K
collected at 123(2) K using
a
radiation (k = 0.71070 Å). The data were
scan in the h range of 2.2 6 h 6
CH3 of Cp*), 1.86 (s, 3H, o-CH3 of mesityl), 2.32 (s, 3H, p-CH3 of
mesityl), 2.50 (s, 3H, o-CH3 of mesityl), 6.83 (s, 1H, Ph), 7.14 (s,
x
27.5° (1c) and 3.1 6 h 6 27.5° (2c). The data obtained were pro-
cessed using Crystal-Clear (Rigaku) on a Pentium computer, and
were corrected for Lorentz and polarization effects. The structures
were solved by direct methods [12], and expanded using Fourier
techniques [13]. The non-hydrogen atoms were refined anisotrop-
1H, Ph). 13C{1H} NMR (150 MHz, THF-d8, r.t.):
d 11.3 (s,
C5(CH3)5), 20.9 (s, o-CH3 of mesityl), 21.2 (s, p-CH3 of mesityl),
25.4 (s, o-CH3 of mesityl), 35.5 (s, C(CH3)3), 57.9 (s, C(CH3)3),
106.7 (s, C5(CH3)5), 128.4, 129.3, 136.2, 138.4, 138.7, 139.6 (Ph),

800
H. Kondo et al. / Journal of Organometallic Chemistry 694 (2009) 795–800
155;
ically except for the disordered solvent atoms (toluene for 2c).
Hydrogen atoms were refined using the riding model. The final cy-
cle of full-matrix least-squares refinement on F2 was based on
5781 observed reflections and 324 variable parameters for 1c,
8527 observed reflections and 474 variable parameters for 2c.
Neutral atom scattering factors were taken from Cromer and Wab-
er [14]. All calculations were performed using the CrystalStructure
[15,16] crystallographic software package. Details of final refine-
ment as well as the bond lengths and angles are summarized in
the supporting information, and the numbering scheme employed
is also shown in the supporting information, which were drawn
with ORTEP at 50% probability ellipsoid.
(c) B. Olbrich-Duessner, W. Kaim, R. Gross-Lannert, Inorg. Chem. 28 (1989)
3113;
(d) T. van Houwelingen, D.J. Stufkens, A. Oskam, Coord. Chem. Rev. 111 (1991)
325.
[6] Y. Yamaguchi, H. Nagashima, Organometallics 19 (2000) 725.
[7] (a) H. Nagashima, H. Kondo, T. Hayashida, Y. Yamaguchi, M. Gondo, S. Masuda,
K. Miyazaki, K. Matsubara, K. Kirchner, Coord. Chem. Rev. 245 (2003) 177;
(b) H. Nagashima, M. Gondo, S. Masuda, H. Kondo, Y. Yamaguchi, K.
Matsubara, Chem. Commun. (2003) 442;
(c) T. Hayashida, H. Nagashima, Organometallics 21 (2002) 3884;
(d) T. Hayashida, Y. Yamaguchi, K. Kirchner, H. Nagashima, Chem. Lett. (2001)
954;
(e) T. Hayashida, K. Miyazaki, Y. Yamaguchi, H. Nagashima, J. Organomet.
Chem. 634 (2001) 167;
(f) H. Kondo, A. Kageyama, Y. Yamaguchi, M. Haga, K. Kirchner, H. Nagashima,
Bull. Chem. Soc. Jpn. 74 (2001) 1927;
(g) T. Hayashida, H. Nagashima, Organometallics 20 (2001) 4996;
(h) H. Kondo, Y. Yamaguchi, H. Nagashima, Chem. Commun. (2000) 1075;
(i) T. Hayashida, H. Kondo, J. Terasawa, K. Kirchner, Y. Sunada, H. Nagashima, J.
Organomet. Chem. 692 (2007) 382.
Acknowledgements
This work was supported by Grant-in-Aid for Science Research
on Priority Areas (No. 18064014, Synergy of Elements) from Minis-
try of Education, Culture, Sports, Science and Technology, Japan.
[8] (a) D.N. Dhar, Chem. Rev. 67 (1967) 611;
(b) J.S. Miller, Angew. Chem., Int. Ed. 45 (2006) 2508.
[9] [a] see ref (6d).;
(b) T.J. Johnson, K. Folting, W.E. Streib, J.D. Martin, J.C. Huffman, S.A. Jackson, O.
Eisenstein, K.G. Caulton, Inorg. Chem. 34 (1995) 488;
(c) K. Mashima, H. Kaneyoshi, S. Kaneko, A. Mikami, K. Tani, A. Nakamura,
Organometallics 16 (1997) 1016;
(d) E.J. Derrah, D.A. Pantazis, R. McDonald, L. Rosenberg, Organometallics 26
(2007) 1473;
(e) W.M. Cheung, Q.-F. Zhang, I.D. Williams, W.H. Leung, Inorg. Chim. Acta 359
(2006) 782;
(f) V.N. Sapunov, R. Schmid, K. Kirchner, H. Nagashima, Coord. Chem. Rev.
238–239 (2003) 363;
Appendix A. Supplementary material
Supplementary data associated with this article can be found, in
the online version, at doi:10.1016/j.jorganchem.2008.12.030.
References
(g) C. Gemel, J.C. Huffman, K.G. Caulton, K. Mauthner, K. Kirchner, J.
Organomet. Chem. 593–594 (2000) 342;
(h) C. Gemel, V.N. Sapunov, K. Mereiter, M. Ferencic, R. Schmid, K. Kirchner,
Inorg. Chim. Acta 286 (1999) 114;
(i) C. Gemel, K. Mereiter, R. Schmid, K. Kirchner, Organometallics 16 (1997)
5601;
(j) U. Koelle, Chem. Rev. 98 (1998) 1313;
[1] (a) W. Kaim, M. Moscherosch, Coord. Chem. Rev. 129 (1994) 157;
(b) D. de Caro, C. Faulmann, L. Valade, Chem. Eur. J. 13 (2007) 1650;
(c) J.S. Miller, A.J. Epstein, W.M. Reiff, Chem. Rev. 88 (1988) 201;
(d) J.S. Miller, A.J. Epstein, W.M. Reiff, Acc. Chem. Res. 21 (1988) 114.
[2] R.H. Crabtree (Ed.), The Organometallic Chemistry of the Transition Metals, 4th
ed., Wiley, New York, 2001, p. 125 (Chapter 3).
[3] (a) R.M. Rettig, R.M. Wing, Inorg. Chem. 8 (1969) 2685;
(b) H. Braunwarth, F. Hutter, L. Zsolnai, J. Organomet. Chem. 372 (1989) C23.
[4] (a) For example, see: G. Wang, H. Zhu, J. Fan, C. Slebodnick, G.T. Yee, Inorg.
Chem. 45 (2006) 1406;
(k) C.D. Tagge, R.G. Bergman, J. Am. Chem. Soc. 118 (1996) 6908.
[10] Diamagnetic nature of 2c can be interpreted in terms of the antiferromagnetic
coupling between TCNEꢀꢀ and Ru(III) center. See Refs. [1a,3a,4c,8a].
[11] P.J. Fagan, M.D. Ward, J.C. Calabrese, J. Am. Chem. Soc. 111 (1989) 1698.
[12] (a) G.M. Sheldrick, SHELX97, 1997.;
(b) F. Baumann, M. Heilmann, W. Matheis, A. Schulz, W. Kaim, J. Jordanov, J.
Organomet. Chem. 251 (1996) 236;
(c) M.J. Macazaga, M.S. Delgado, J.R. Masaguer, J. Organomet. Chem. 310
(1986) 249;
(b) A. Altomare, M.C. Burla, M. Camalli, G. Cascarano, A. Guagliardi, A.
Moliterni, G. Polidori, R. Spagna, SIR97, 1999.
[13] P.T. Beurskens, G. Admiraal, G. Beurskens, W.P. Bosman, R. de Gelder, R. Israel,
J.M.M. Smits, The DIRDIF-99 Program System; Technical Report of the
Crystallography Laboratory, University of Nijmegen, Nijmegen, The
Netherlands, 1999.
[14] D.T. Cromer, J.T. Waber, International Tables for X-ray Crystallography, vol. 4,
Kynoch Press, Birmingham, UK, 1974.
[15] CrystalStructure 3.8.0: Crystal Structure Analysis Package; Package, Rigaku
and Rigaku/MSC, 9009 New Trails Dr, The Woodlands TX 77381 USA, 2000–
2006.
[16] J.R. Carruthers, J.S. Rollett, P.W. Betteridge, D. Kinna, L. Pearce, A. Larsen, E.
Gabe, CRYSTALS Issue 11, Chemical Crystallography Laboratory, Oxford, UK,
1999.
(d) M.J. Macazaga, M.S. Delgado, J.R. Masaguer, J. Organomet. Chem. 299
(1986) 377;
(e) S.D. Ittel, C.A. Tolman, P.J. Krusic, A.D. English, J.P. Jesson, Inorg. Chem. 17
(1978) 3432;
(f) S.I. Amer, T.P. Dasgupta, P.M. Henry, Inorg. Chem. 22 (1983) 1970;
(g) B. Olbrich-Duessner, W. Kaim, R. Gross-Lannert, Inorg. Chem. 29 (1990)
5046.
[5] (a) For instance, Kaim et al. have reported the excellent works concerning with
isomerization of TCNE from
reduction of the parent
g g
2(C)-TCNE to 1(N)-coordination achieved by the
g
2(C)-TCNE complexes electrochemically or
2(C)- to
chemically. For further details of the rearrangement of TCNE from
1(N)-coordination, see: T. Roth, W. Kaim, Inorg. Chem. 31 (1992) 1930;
(b) B. Olbrich-Duessner, R. Gross, W. Kaim, J. Organomet. Chem. 366 (1989)
g
g