Synthesis, structure, and reactivity of RuII complexes with trimethylsilylethinylamidinate ligands

Article abstract of DOI:10.1002/zaac.201100431

The mononuclear amidinate complexes [(η⁶-cymene)-RuCl(1a)] (2) and [(η⁶-C₆H₆)RuCl(1b)] (3), with the trimethylsilyl-ethinylamidinate ligands [Me₃SiC≡CC(N-c-C ₆H₁₁)₂]

Full text of DOI:10.1002/zaac.201100431

ARTICLE
DOI: 10.1002/zaac.201100431
Synthesis, Structure, and Reactivity of RuII Complexes with
Trimethylsilylethinylamidinate Ligands
Wolfram W. Seidel,*[a] Woldemar Dachtler,[a] and Tania Pape[b]
Keywords: N-ligands; Metathesis; Chelates; Substituent effects; X-ray diffraction
Abstract. The mononuclear amidinate complexes [(η6-cymene)-Ru- change reactions. Investigations on the removal of the trimethyl-silyl
Cl(1a)] (2) and [(η6-C6H6)RuCl(1b)] (3), with the trimethylsilyl-ethin-
ylamidinate ligands [Me3SiCϵCC(N-c-C6H11)2]– (1a–) and
group using [Bu4N]F resulted in the isolation of [(η6-C6H6)-
Ru(PPh3){(N-i-C3H7)2CCϵCH}](BF4) (6-BF4) bearing a terminal alk-
[Me3SiCϵCC(N-i-C3H7)2]– (1b–) were synthesized in high yields by ynyl hydrogen atom, while 2 and 3 revealed to yield intricate reaction
salt metathesis. In addition, the related phosphane complexes mixtures. Compounds 1a/b to 6-BF4 were characterized by multinu-
[(η5-C5H5)Ru(PPh3)(1b)] (4a) [(η5-C5Me5)Ru(PPh3)(1b)] (4b), and clear NMR (1H, 13C, 31P) and IR spectroscopy and elemental analyses,
[(η6-C6H6)Ru(PPh3)(1b)](BF4) (5-BF4) were prepared by ligand ex-
including X-ray diffraction analysis of 1b, 2, and 3.
cene derivative shows electronic cooperation with the
M2(O2CMe)2 moiety as indicated by cyclic voltammetry. Ac-
cordingly, related coordination polymers with A2– represent
promising materials with presumably interesting opto-elec-
tronic properties.
Introduction
In the course of our studies with donor-substituted acetyl-
enes[1] we came across bis(amidinate) and bis(dithiocarboxyl-
ate) ligands, which show a direct linkage by acetylene moie-
ties. Such acetylene-bis(amidinate) and acetylene-bis(dithi-
ocarboxylate) ligands (A2–, B2–) as well as the mixed prototype
C2– (Figure 1) constitute interesting building blocks for one-
dimensional coordination polymers. Within this scheme the in-
dividual donor moieties can either adopt a chelating or a bridg-
ing coordination mode. Homoleptic complexes with square-
planar coordination structure, which could serve as linker, are
well known for both amidinate[2] and dithiocarboxylate[3] li-
gands. In addition, the limited stability of complex centers with
four-membered chelate rings is considered favorable for the
formation of definite coordination polymers, because certain
lability will allow the rearrangement of coordination misfits.
The electronic cooperation of metal ions connected by the li-
gands A2– to C2– through the conjugated bridge might confer
respective materials with desirable electronic properties like
directed conductivity and high absorptivity at comparatively
low energies. For instance, the Chisholm group presented re-
cently dinuclear molybdenum and tungsten complexes, in
which M2(O2CMe)2 units are coordinated by two phenylalk-
ynyl- or ferrocenylalkynyl-amininate ligands in trans-configu-
ration.[4a] These complexes are highly colored and the ferro-
Figure 1. Amidinate- and dithiocarboxylate ligands bridged by an
acetylene moiety.
Whereas quite a number of coordination compounds of al-
kyne-amidinate ligands with predominantly lanthanide ions
have appeared within the last years[5] and some alkyne-dithi-
ocarboxylate complexes were published within the last dec-
ades,[6] complexes with ligands A2– to C2– are unknown so far.
One reason for this gap seems to be the unclear access to the
di-anionic ligands or, alternatively, the protonated forms. In
preliminary attempts we encountered considerable difficulties
in the synthesis of Li2-A and particularly Li2-B. Li2-A (R =
cyclo-C6H11) can be prepared by reaction of Li2C2 with dicy-
clohexylcarbodiimide in THF. After protonation the product
H2-A was detected by mass spectrometry. However, the isola-
tion of analytically pure samples by various purification meth-
ods turned out to be cumbersome due to the low solubility,
which reflects the presumably polymeric structures. Accord-
ingly, coordination experiments with the raw material Li2-A
* Prof. Dr. W. W. Seidel
Fax: +49-381-4986382
E-Mail: wolfram.seidel@uni-rostock.de
[a] Universität Rostock
Institut für Chemie
Albert-Einstein-Straße 3a
18059 Rostock, Germany
[b] Westfälische Wilhelms-Universität Münster
Institut für Anorganische und Analytische Chemie
Corrensstraße 28/30
48149 Münster, Germany
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RuII Complexes with Trimethylsilylethinylamidinate Ligands
led to equivocal products. Therefore, we sought for a step by
step procedure for the generation of acytelene-bis(amidinate)
ligands.
Our long-term approach comprises the synthesis of mononu-
clear complexes with hitherto unknown trimethylsilylethinyl-
amidinate ligands and the subsequent insertion of a second am-
idinate or dithiocarboxylate group via the corresponding ter-
minal alkyne after removal of the trimethylsilyl group. Inser-
tions reactions of carbodiimides or CS2 into metal-acetylide
bonds according to Scheme 1 were regularly observed[5d,5e,6a–
c,6e]
and respective catalytic procedures for the conversion of
terminal alkynes into alkyne-amidinates are published.[5a] In
this contribution we give a progress report on the prospects of
this strategy. We describe the synthesis and structure of trime-
thylsilylethinyl-amidinate ligands and a number of RuII com-
plexes with ancillary π ligands. In addition, we report on in-
vestigations on the removal of the trimethylsilyl group in all
complexes prepared.
Scheme 2. Synthesis of alkynyl-amidinate ligands and its RuII com-
plexes: (i) [(η6-cymene)RuCl(μ-Cl)]2, THF; (ii) [(η6-benzene)RuCl-
(μ-Cl)]2, THF; (iii) [(η5-C5R5)Ru(PPh3)(NCMe)2]PF6 (R = H, Me),
THF.
Scheme 1. Outline of the synthetic strategy.
Results and Discussion
The lithium amidinates used for coordination experiments
were prepared in ethyl ether from the reaction between either
diisopropylcarbodiimide or dicyclohexylcarbodiimide and lith-
Figure 2. Molecular structure of dimer (Li-1b)2·2Et2O in the crystal
with thermal ellipsoids set at 40% probability. Hydrogen atoms are
ium trimethylsilylacetylide as shown in Scheme 2. The acet- omitted for clarity. Selected bond lengths /Å and angles /°: Li1–N1
2.002(4), Li1–N2 2.243(4), Li1–N2* 2.042(4), Li1–O1 1.923(4), C1–
ylide was obtained in situ by standard deprotonation of
N1 1.324(3), C1–N2 1.331(3), C1–C2 1.466(3), C2–C3 1.203(3), C3–
Me3SiCϵCH, which is commercially available. The use of
Si1 1.829(2), N1–C1–N2 119.8(2), C1–C2–C3 174.3(3), C2–C3–Si1
ethyl ether as solvent proved to be favorable, because
Li[(c-C6H11N)2CCϵCSiMe3] (Li-1a) and Li[(i-C3H7N)2-
CCϵCSiMe3] (Li-1b) could be obtained in crystalline form
as white salts. The solubility in THF is very high, whereas
decomposition occurred in more polar and halogenated sol-
vents. The compounds are very sensitive to hydrolysis and Li-
1a being visibly more stable. Significant spectroscopic features
are the 13C NMR shift of the alkyne carbon atoms at δ = 98.5
and 96.5 ppm (Li-1a). The low intensity of the latter signal is
indicative of the carbon atom directly attached to the amidinate
group. The amidinate carbon atom was detected at δ =
156.6 ppm for both Li-1a and Li-1b. Both samples were exam-
ined by single-crystal X-ray diffraction. The molecular struc-
ture of (Li-1b)2·2 Et2O is depicted in Figure 2.
175.3(2).
Both examples form dimeric structures having a crystallo-
graphically imposed inversion center. The amidinate moieties
serve as a chelate with one lithium ion, whereas one of the
nitrogen donor atoms additionally bridges to the second lith-
ium atom and vice versa. Accordingly, the lithium ions are
four coordinate in a pseudo-tetrahedral fashion. This structural
motif has been well documented and the metric parameters are
not exceptional.[4]
Metathesis reactions of the amidinate salts Li-1a and Li-1b
with the RuII complexes [(η6-cymene)RuCl(μ-Cl)]2 or [(η6-
benzene)RuCl(μ-Cl)]2 in THF led to the formation of the mon-
omolecular complexes [(η6-cymene)RuCl(1a)] and [(η6-ben-
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117

W. W. Seidel, W. Dachtler, T. Pape
ARTICLE
zene)RuCl(1b)] according to Scheme 2. The neutral brown cy- Interestingly, the corresponding cationic 16-electron species
mene and green benzene complexes are soluble in toluene and [(η6-C6Me6)Ru(iPrN)2CMe]+ displays a chelate ring folding
were eventually isolated analytically pure as [(η6-cymene)Ru- of 31.4°, which is attributed to a weak π coordination of the
Cl(1a)] (2) and [(η6-benzene)RuCl(1b)] (3) by crystallization amidinate.[7a]
from toluene solution at low temperature. The coordination of
ruthenium alters the NMR spectroscopic features of the amid-
inate ligands only marginally. The 13C NMR shift of the amid-
inate carbon atom is observed at 157.0 ppm for 2 and
156.2 ppm for 3. Both complexes could be characterized by
single-crystal X-ray diffraction. The molecular structure of 2
is depicted in Figure 3 together with relevant metrical param-
eters. The complex displays a standard half sandwich structure
with η6-bonded cymene. The amidinate ligand 1a– is coordi-
nated in a chelate like fashion to ruthenium. The remaining
chloride substituent is directed almost perpendicular to the che-
late ring plane spanned by N1, C1, N2, and Ru. The Ru–N
bond lengths (Ru–N1 and Ru–N2) amount to 2.132(2) Å and
2.095(2) Å, respectively. The N1–C1–N2 angle has decreased
to 111.2(2)° as compared with the corresponding angle of
119.8(2)° in Li-1b.
Figure 4. Molecular structure of 3 in the crystal with thermal ellipsoids
set at 40% probability. Hydrogen atoms are omitted for clarity. Se-
lected bond lengths /Å and angles /°: Ru1–N1 2.0878(18), Ru1–N2
2.1057(18), Ru1–Cl1 2.4083(7), C1–N1 1.322(3), C1–N2 1.321(3),
C1–C2 1.448(3), C2–C3 1.198(3), C3–Si1 1.847(3), N1–C1–N2
110.3(2), C1–C2–C3 176.6(3), C2–C3–Si1 177.0(3).
Trimethylsilyl groups attached to alkyne carbon atoms are
usually removed by fluoride ions in THF/methanol mixtures
or with K2CO3 in methanol. Cleavage of the trimethylsilyl
group is indeed observed with 2 and 3 as indicated by NMR
spectroscopy; however, we were not able to isolate analytically
pure products. We assume the persistent reactivity of the chlor-
ide substituent to be the reason for that observation. Therefore,
we tried to substitute the chloride ion by neutral π-acceptor
ligands like phosphanes and isocyanides in order to block that
position. Reaction of the cymene complex 2 with Ag[BF4] in
CH2Cl2 led to precipitation of AgCl, however, the coordination
of different phosphanes or dimethylaminopyridine (DMAP)
turned out to be impossible. Solely, adduct formation of the
isocyanide tBuNC with intermediate [(cymene)Ru(1a)]+ could
be proven spectroscopically (IR, NMR). We attribute this be-
havior to the strong steric hindrance in complex 2 as is evident
in the molecular structure (Figure 3). Accordingly, reaction of
the corresponding benzene complex 3 with Ag[BF4] in CH2Cl2
and subsequent addition of PPh3 resulted smoothly in the for-
mation of the reddish brown phosphane complex [(η6-ben-
zene)Ru(1b)(PPh3)]BF4 (5-BF4) (Scheme 3). The air-stable
Figure 3. Molecular structure of 2 in the crystal with thermal ellipsoids
set at 50% probability. Hydrogen atoms are omitted for clarity. Se-
lected bond lengths /Å and angles /°: Ru1–N1 2.1318(17), Ru1–N2
2.0946(18), Ru1–Cl1 2.4213(6), C1–N1 1.327(3), C1–N2 1.320(3),
C1–C2 1.448(3), C2–C3 1.198(3), C3–Si1 1.843(2), N1–C1–N2
111.2(2), C1–C2–C3 174.0(2), C2–C3–Si1 170.6(2).
The molecular structure of 3 is shown in Figure 4. The met- complex, which could be isolated by precipitation from a THF/
rical parameters of the sterically less encumbered complex 3 n-hexane solvent mixture, was characterized spectroscopically.
are similar to that of 2. The Ru–N distances of Ru–N1 with The 31P NMR shift of 5-BF4 was found at 33.1 ppm; the amid-
2.088(2) Å and of Ru–N2 with 2.106(2) Å are somewhat but inate carbon atom resonates at 163.7 ppm in the 13C NMR
significantly shorter. The N1–C1–N2 angle amounts to spectrum. The identity of 5-BF4 is further substantiated by ele-
110.3(2)°. The structure data are similar to related RuII amidin- mental analysis and MALDI-TOF mass spectrometry. Subse-
ate complexes published by the Nagashima group,[7] which quent reaction of 5-BF4 with catalytic amounts of [Bu4N]F in
show the weak influence of the type of π ligand at ruthenium THF/CH3OH yielded slowly the complex [(η6-C6H6)
and the substituent at the amidinate carbon atom on the Ru–N Ru{(iPrN)2CCϵCH}(PPh3)]BF4 (6-BF4) with a terminal al-
distance. However, steric effects are rather evident, because kyne function. The 31P NMR resonance of complex 6-BF4 was
complex 2 shows a folding of the chelate ring about the NN detected to be only slightly changed at 32.9 ppm. The most
axis of 18.3° and a distinct deviation of the alkyne from linear- dramatic shift observed in the 13C NMR spectra going from 5-
ity. Both features are much less pronounced in complex 3. BF4 to 6-BF4 applies to the alkyne carbon atom attached to
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Z. Anorg. Allg. Chem. 2012, 116–121

RuII Complexes with Trimethylsilylethinylamidinate Ligands
silicon in 5-BF4 (96.4 ppm) and to hydrogen in 6-BF4
(67.8 ppm). The range around 70 ppm is typical for terminal
protons of alknyes. In addition, the cation [6+]
(m/z = 593) could be identified by MALDI-TOF mass spec-
trometry.
Experimental Section
General: All operations were carried out in a dry argon atmosphere
by using standard Schlenk and glove box techniques. All solvents were
dried and saturated with argon by standard methods and freshly dis-
tilled prior to use. Trimethylsilylacetylene was purchased from Ald-
rich. [(η6-cymene)RuCl(μ-Cl)]2, [(η6-benzene)RuCl(μ-Cl)]2, [(η5-
C5H5)Ru(PPh3)(NCMe)2]PF6, and [(η5-C5Me5)Ru(PPh3)(NCMe)2]PF6
were synthesized according to literature procedures.[8] NMR spectra
(1H, 31P, 13C) were recorded with the Bruker spectrometers AC 200
and Avance 400. Elemental analyses were performed with a Vario EL
III CHNS elemental analyzer. MALDI mass spectra were obtained
with a Bruker Reflex IV spectrometer using [(2E)-3-(4-tert-bu-
tylphenyl)-2-methylprop-2-enyliden]malononitrile (DCTB) as matrix.
Infrared spectra were recorded with a Bruker Vektor 22 spectrometer.
Li[(c-C6H11N)2CCϵCSiMe3]
(Li-1a):
Trimethylsilylacetylene
Scheme 3. Synthesis of a RuII ethinylamidinate complex: (i) Ag[BF4],
PPh3, CH2Cl2; (ii) [Bu4N]F, MeOH, THF.
(4.3 mL, 30 mmol) dissolved in diethyl ether (40 mL) and cooled to
–78 °C was treated with n-butyllithium (2.5 m solution in n-hexane,
12 mL). After 10 min 1,3-dicyclohexyl-carbodiimide (6.2 g, 30 mmol)
was added and the mixture was stirred for 30 min at –78 °C. Upon
warming to room temperature, the reaction was complete in the course
of two h. Then the solution was concentrated to a small volume and
In order to test the influence of the total charge on the repro-
ducibility and complex stability we additionally synthesized
the complexes [(η5-C5H5)Ru(PPh3)(1b)] (4a) and [(η5-C5Me5)
Ru(PPh3)(1b)] (4b). Both were accessible by reaction of Li- cooled to –30 °C overnight. The precipitate formed was filtered off,
1b with the acetonitrile complexes [(η5-C5R5)Ru(PPh3)
washed with cold diethyl ether (3 mL) and dried in vacuo. The product
was recrystallized from diethyl ether/n-hexane (5:1). Yield 91%. Ele-
(NCMe)2]PF6 (R = H, Me) according to Scheme 2. The neutral
mental analysis C22H41LiN2OSi (384.60 g·mol–1): C 69.05 (calcd.
complexes 4a and 4b, which were isolated from toluene solu-
68.70); H 10.66 (10.75); N 7.42 (7.28)%. 1H NMR (200 MHz,
tion, show 31P NMR resonances at 46.9 and 46.1 ppm, respec-
[D8]THF, 25 °C): δ = 3.42 (m, 2 H, CH), 1.75–1.00 (m, 20 H, CH2),
0.18 (s, 9 H, SiCH3) ppm. 13C NMR (50 MHz, [D8]THF, 25 °C): δ =
156.6 (CN), 98.5 (SiCϵC), 96.5 (CCϵC), 59.0 (CH), 38.0 (CHCH2),
tively. The reaction of 4a/b with a catalytic quantity of
[Bu4N]F in THF/CH3OH led to the removal of the trimethyl-
silyl group as indicated by 1H NMR evidence. The crude prod-
27.3 (CHCH2CH2), 27.0 (CHCH2CH2CH2), 0.2 (SiCH3) ppm. IR
uct [(η5-C5H5)Ru{(iPrN)2CCϵCH}(PPh3)] (7) displayed a 31
P
(KBr): ν˜ 2144 (s, CϵC), 1597 (s, CN) cm–1. MS (MALDI): m/z = 305
(M++ 2 H, 100%).
NMR resonance at 51.8 ppm and the correct molecular of mass
m/z = 580 in the MALDI-TOF mass spectrum. However, we
were not able to isolate an analytically pure sample of complex
7. The corresponding reaction with 4b led to an even more
intricate reaction mixture.
Li[(iPrN)2CCϵCSiMe3] (Li-1b): Li-1b was prepared in a scale of
50 mmol (50 mL diethyl ether) as described for Li-1a by using 1,3-
diisopropylcarbodiimide (6.9 mL, 50 mmol). Yield 76%. Elemental
analysis C16H33LiN2OSi (304.47 g·mol–1): C 62.42 (calcd. 63.12), H
10.81 (10.92), N 9.38 (9.20)%. 1H NMR (200 MHz, [D8]THF, 25 °C):
δ = 3.78 (sept, 3J = 6.2 Hz, 2 H, CH), 0.97 [d, 3J = 6.2 Hz, 12 H,
CH(CH3)2], 0.17 (s, 9 H, SiCH3) ppm. 13C NMR (50 MHz, [D8]THF,
25 °C): δ = 156.6 (CN), 98.0 (SiCϵC), 97.1 (CCϵC), 50.1 [CH(CH3)2],
26.8 [CH(CH3)2], 0.2 (SiCH3) ppm. IR (KBr): ν˜ 2137 (s, CϵC), 1605
(s, CN) cm–1. MS (MALDI): m/z = 225 (M++ 2 H, 100%).
Conclusions
The coordination of trimethylsilylethinyl-amidinate ligands
at RuII half sandwich complexes (R = cymene, benzene, cyclo-
pentadienyl) could be readily achieved by salt metathesis. Be-
forehand, the respective Li-amidinate ligands were straightfor-
wardly obtained by deprotonation of trimethylsilylacetylen and
subsequent reaction with carbodiimides (R = cyclohexyl, iso-
propyl). The intended removal of the trimethylsilyl group at
the complexes was observed in all cases. However, the isola-
[(η6-Cymene)RuCl(1a)] (2):
A
solution of Li-1a (675 mg,
2.17 mmol) in THF (20 mL) was added to a suspension of [(η6-cy-
mene)RuCl(μ-Cl)]2 (604 mg, 1.09 mmol) in THF (70 mL). After stir-
ring overnight, the solvent was evaporated under reduced pressure.
The residue was extracted into toluene (3ϫ10 mL), filtered and the
solvent was evaporated to dryness. Yield 99%. Complex 2 crystallized
tion of stable and pure ethinylamidinate complexes turned out in analytically pure form from a saturated toluene solution upon cool-
ing to –30 °C. Elemental analysis C28H45ClN2RuSi (574.28 g·mol–1):
to be very sensitive to the particular ligand set. Ambiguous
conversions were particularly observed with chlorido substitu-
C 59.02 (calcd. 58.56), H 7.98 (7.90), N 4.79 (4.88)%. 1H NMR
(400 MHz, CDCl3, 25 °C): δ = 5.03 [d, 3J = 6.4 Hz, 2 H, (CH3)2-
ents at ruthenium. Best results were obtained with cationic
3
CHCCH], 4.74 (d, J = 6.4 Hz, 2 H, CH3CCH), 3.49 (m, 2 H, NCH),
[(η6-C6H6)Ru(1b)(PPh3)]BF4 leading to the desired complex
3
2.65 (sept, J = 6.8 Hz, 1 H, CCH), 2.43 (m, 2 H, CHCH2), 2.25 (m,
[(η6-C6H6)Ru{(iPrN)2CCϵCH}(PPh3)]BF4. We assume that
2 H, CHCH2), 2.05 (s, 3 H, CCH3), 1.85–1.20 [m, 16 H, NCH(CH2)2-
consecutive reactions with the terminal alkyne proton like for-
mation of vinylidene complexes, which is typical for RuII,
could explain the restricted applicability of the approach with
RuII. Further investigations with more Lewis acidic and less
electron rich metal ions are underway.
(CH2)2CH2], 1.09 [d, 3J = 6.8 Hz, 6 H, CH(CH3)2], 0.05 (s, 9 H,
SiCH3) ppm. 13C NMR (100 MHz, CDCl3, 25 °C) : δ = 157.0 (CN),
99.3 [CCH(CH3)2], 98.6 (CCH3), 97.0 (SiCϵC), 94.7 (CCϵC), 79.7,
78.5 (Ar-C), 58.9 (NCH), 36.9, 36.2 [NCH(CH2)2], 32.4 [CCH(CH3)2],
26.7, 26.4, 26.3 [NCH(CH2)2(CH2)2CH2], 22.8 [CCH(CH3)2], 19.4
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W. W. Seidel, W. Dachtler, T. Pape
ARTICLE
(CCH3), –0.4 (SiCH3) ppm. MS (MALDI): m/z = 574 (M+, 30%); 539
[(η6-C6H6)Ru(1b)(PPh3)]BF4 (5-BF4): A solution of 3 (1.00 g,
1.91 mmol) in dichloromethane (50 mL) was cooled to –78 °C. AgBF4
(372 mg, 1.91 mmol) was added. The resulting mixture was warmed
to room temperature and stirred for 30 min. To the resulting brown
suspension PPh3 (600 mg, 1.91 mmol) was added. The mixture was
stirred for 2 h and then dried by evaporation of the volatiles. The resi-
due was dissolved in THF, filtered, and the filtrate was reduced to a
small volume. The addition of hexane followed by cooling afforded
the product as a brown solid. Yield 71%. Elemental analysis
C36H44BF4N2PRuSi (751.68 g·mol–1): C 58.02 (calcd. 57.52), H 5.95
(5.90), N 3.69 (3.73)%. 1H NMR (200 MHz, CDCl3, 25 °C): δ = 7.48–
(M+–Cl, 100%).
[(η6-Benzene)RuCl(1b)] (3): A solution of compound Li-1b (461 mg,
2.00 mmol) in THF (20 mL) was added to a suspension of [(η6-ben-
zene)RuCl(μ-Cl)]2 (1.00 g, 2.00 mmol) in THF (50 mL). After stirring
overnight, the solvent was evaporated under reduced pressure. The
residue was extracted into toluene (3ϫ10 mL), filtered and the green
filtrate was reduced in volume. Complex 3 crystallized upon cooling
to –30 °C. Yield 81%. Elemental analysis C18H29ClN2RuSi
(438.05 g·mol–1): C 49.96 (calcd. 49.35), H 6.78 (6.67), N 6.28
(6.40)%. 1H NMR (200 MHz, C6D6, 25 °C): δ = 4.93 (s, 6 H, η6-
3
7.20 (m, 15 H, Ar-H), 5.77 (s, 6 H, η6-C6H6), 3.25 [sept, J = 6.2 Hz,
3
3
C6H6), 3.99 (sept, J = 6.2 Hz, 2 H, CH), 1.43 (d, J = 6.2 Hz, 6 H,
2 H, CH(CH3)2], 0.97 (d, 3J = 6.2 Hz, 6 H, CH3), 0.81 (d, 3J = 6.2 Hz,
6 H, CH3), 0.19 (s, 9 H, SiCH3) ppm. 13C NMR (50 MHz, CDCl3,
25 °C): δ = 163.7 (CN), 134.3–128.4 (Ar-C), 96.4 (SiCϵC), 92.2
(CCϵC), 89.1 (η6-C6H6), 51.2 [CH(CH3)2], 24.0, 23.3 [CH(CH3)2],
–0.8 (SiCH3) ppm. 31P NMR (81 MHz, CDCl3, 25 °C): δ = 33.08
(PPh3) ppm. MS (MALDI): m/z = 665 (M+, 100%), 403 (M+–PPh3,
30%).
CH3), 1.31 (d, J = 6.2 Hz, 6 H, CH3), 0.06 (s, 9 H, SiCH3) ppm. 13C
3
NMR (50 MHz, C6D6, 25 °C): δ = 156.2 (CN), 97.1 (SiCϵC), 93.8
(CCϵC), 81.3 (η6-C6H6), 50.6 [CH(CH3)2], 25.6, 25.5 [CH(CH3)2],
–0.5 (SiCH3) ppm. MS (MALDI): m/z = 438 (M+, 80%); 403 (M+–
Cl, 100%).
[(η5-C5H5)Ru(1b)(PPh3)] (4a):
A solution of Li-1b (78 mg,
0.34 mmol) in THF (20 mL) was added to a solution of [(η5-C5H5)
Ru(PPh3)(NCMe)2]PF6 (300 mg, 0.34 mmol) in THF (40 mL). After
stirring overnight, the solvent was evaporated under reduced pressure.
The residue was extracted into toluene (3ϫ10 mL) and filtered. Con-
centration and cooling to –30 °C yielded the product as a brown solid.
Yield 72%. 1H NMR (200 MHz, C6D6, 25 °C): δ = 7.20–7.00 (m, Ar-
[(η6-C6H6)Ru{(iPrN)2CCϵCH}(PPh3)]BF4 (6-BF4): Pure 5-BF4
(217 mg, 0.30 mmol) was dissolved in THF (15 mL). Methanol (8 mL)
and tetrabutylammonium fluoride (7 mg, 0.02 mmol) were added and
the mixture was stirred for 3 d at room temperature. After removal of
the solvents under reduced pressure 6-BF4 was obtained from THF/n-
hexane and cooling to –40 °C as a brown solid. Yield 91%. Elemental
analysis C33H36BF4N2PRu (679.50 g·mol–1): C 58.92 (calcd. 58.33), H
3
3
H), 4.33 (s, η5-C5H5), 3.82 (sept, J = 6.4 Hz, 2 H, CH), 1.21 [d, J =
3
6.4 Hz, 6 H, CH(CH3)2], 0.64 [d, J = 6.4 Hz, 6 H, CH(CH3)2], 0.16
(s, 9 H, SiCH3) ppm. 31P NMR (81 MHz, C6D6, 25 °C): δ = 46.9
(PPh3) ppm. MS (MALDI): m/z = 429 (M+–1b, 40%).
1
5.39 (5.34), N 4.05 (4.12)%. H NMR (200 MHz, CDCl3, 25 °C): δ
= 7.71–7.26 (m, 15 H, Ar-H), 5.77 (s, 6 H, η6-C6H6), 3.16 [m, 2 H,
CH(CH3)2], 2.14 (CϵCH), 0.98, 0.90 (m, 12 H, CHCH3) ppm. 13C
NMR (50 MHz, CDCl3, 25 °C): δ = 155.3 (CN), 134.1–127.9 (Ar-C),
89.1 (η6-C6H6), 88.5 (CCϵC), 67.8 (HCϵC), 57.0 [CH(CH3)2], 24.2,
23.3 [CH(CH3)2] ppm. 31P NMR (81 MHz, CDCl3, 25 °C): δ = 32.9
(PPh3) ppm. MS (MALDI): m/z = 593 (M+, 100%); 331 (M+–PPh3,
80%).
[(η5-C5Me5)Ru(1b)(PPh3)] (4b): Compound 4b was prepared as de-
1
scribed for 4a. H NMR (200 MHz, C6D6,25 °C): δ = 7.40–6.80 (m,
3
Ar-H), 3.39 (sept, J = 6.4 Hz, 2 H, CH), 2.11 [s, η5-C5(CH3)5], 1.25
[d, 3J = 6.4 Hz, 6 H, CH(CH3)2], 1.21 [d, 3J = 6.4 Hz, 6 H, CH(CH3)2],
0.14 (s, 9 H, SiCH3) ppm. 31P NMR (81 MHz, C6D6, 25 °C): δ = 46.1
(PPh3) ppm. MS (MALDI): m/z = 499 (M+–1b, 40%).
Table 1. Crystallographic details for Li-1b, 2 and 3.
(Li-1b)2·2Et2O
2
3
Formula
C32H66Li2N4O2Si2
608.95
C28H45ClN2RuSi
574.27
orange, prisms
monoclinic
P21/n
10.9689(13)
8.7138(10)
30.480(4)
90
90.035(2)
90
C18H29ClN2RuSi
438.04
brown, prisms
monoclinic
P21/c
11.7906(16)
15.920(2)
12.0483(16)
90
114.246(2)
90
MW /g·mol–1
Color / Habit
Crystal system
Space group
a /Å
colorless, plates
triclinic
¯
P1
9.4334(19)
9.908(2)
13.285(3)
68.274(4)
82.780(4)
62.056(4)
1017.3(4)
1
b /Å
c /Å
α /°
β /°
γ /°
V /Å3
2913.3(6)
4
1.309
2062.0(5)
4
1.411
Z
Dcalcd. /g·cm–1
0.994
0.116
μ /mm–1
0.689
0.949
T /K
153
153
153
2Θmax /°
Collected refl.
Unique refl. / Rint
Variables
R1 [[I Ͼ 2σ(I)]
wR2 (all data)
GooF on F2
Res.dens. /e·Å–3
47.0
7183
3003 / 0.0280
199
0.0500
0.1437
0.894
0.524 / –0.302
60.1
32383
8480 / 0.0424
304
0.0415
0.0827
1.122
0.819 / –0.735
60.06
23590
6016 / 0.0475
215
0.0363
0.0843
1.036
0.801 / –0.386
120
www.zaac.wiley-vch.de
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2012, 116–121

RuII Complexes with Trimethylsilylethinylamidinate Ligands
[(η5-C5H5)Ru{(iPrN)2CCϵCH}(PPh3)] (7): Complex 7 was obtained
following the same procedure as described for 6-BF4, using 4a instead
of 5-BF4. Yield 95%. H NMR (200 MHz, C6D6, 25 °C): δ = 7.20–
9616–9629; d) W. W. Seidel, B. Lopez Sanchez, M. Meel, A.
Hepp, T. Pape, Eur. J. Inorg. Chem. 2007, 936–943; e) W. W. Sei-
del, M. J. Meel, F. Hupka, J. J. Weigand, Dalton Trans. 2010, 39,
624–631.
1
6.90 (m, Ar-H), 4.46 (s, C5H5), 3.40 (m, 2 H, CH), 2.11 (s, 1H,
[2] a) D. A. Kissounko, M. V. Zabalov, G. P. Brusova, D. A. Lemenov-
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3
3
CϵCH), 1.20 [d, J = 6.0 Hz, 6 H, CH(CH3)2], 0.75 [d, J = 6.0 Hz,
6 H, CH(CH3)2] ppm. 31P NMR (81 MHz, C6D6, 25 °C): δ = 51.8
(PPh3) ppm. MS (MALDI): m/z = 580 (M+, 30%); 429 {M+–[(iPrN)2-
CCϵCH], 10%}.
Crystal Structure Determination: Single crystals suitable for X-ray
diffraction analysis were coated with a perfluoropolyether, picked up
with a glass fiber and immediately mounted in the cold nitrogen stream
of the diffractometer. Intensity data were collected at T = 153 K with
a Bruker AXS Apex CCD diffractometer equipped with a rotating an-
ode using graphite monochromated Mo-Kα radiation. Data collection,
cell refinement, data reduction and integration as well as absorption
correction were performed with the Bruker AXS program packages
SMART, SAINT and SADABS. Structure solutions were found with
SHELXS[9a] by direct methods and were refined with SHELXL[9b]
against Fo2 by using anisotropic thermal parameters for all non-hydro-
gen atoms. Hydrogen atoms were included at calculated positions with
fixed thermal parameters. A summary of the crystallographic data and
structure refinement results for complexes [(Li-1b), 2, and 3 are given
in Table 1.
Crystallographic data (excluding structure factors) for the structures in
this paper have been deposited with the Cambridge Crystallographic Data
Centre, CCDC, 12 Union Road, Cambridge CB21EZ, UK. Copies of the
data can be obtained free of charge on quoting the depository numbers
CCDC-845854 [(Li-1b)2·2Et2O], CCDC-845855 (2), and CCDC-845856
(3) (Fax: +44-1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk,
http://www.ccdc.cam.ac.uk).
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Lett. 2001, 954–955; b) T. Hayashida, H. Nagashima, Organome-
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awa, K. Kirchner, Y. Sunada, H. Nagashima, J. Organomet. Chem.
2007, 692, 382–394.
Acknowledgement
[8] a) M. A. Bennett, A. K. Smith, J. Chem. Soc. Dalton Trans. 1974,
233–241; b) E. Rüba, W. Simanko, K. Mauthner, K. M. Soldouzi,
C. Slugovc, K. Mereiter, R. Schmid, K. Kirchner, Organometallics
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[9] a) G. M. Sheldrick, Acta Crystallogr., Sect. A 1990, 46, 467–473;
b) G. M. Sheldrick, Acta Crystallogr., Sect. A 2008, 64, 112–122.
W. W. S. thanks Prof. F. E. Hahn for generous support.
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Received: September 27, 2011
Published Online: November 29, 2011
Z. Anorg. Allg. Chem. 2012, 116–121
© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.zaac.wiley-vch.de
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