Preparation and Structural Characterization of [CpRu(1,10-phenanthroline)(CH3CN)][X] and Precursor Complexes (X=PF6, BArF, TRISPHAT-N)

Article abstract of DOI:10.1002/hlca.202000190

Cationic [Ru(η⁵-C₅H₅)(CH₃CN)₃]⁺ complex, tris(acetonitrile)(cyclopentadienyl)ruthenium(II), gives rise to a very rich organometallic chemistry. Combined with diimine ligands, and 1,10-phenanthroline in particular, this system efficiently catalyzes diazo decomposition processes to generate metal-carbenes which undergo a series of original transformations in the presence of Lewis basic substrates. Herein, syntheses and characterizations of [CpRu(Phen)(L)] complexes with (large) lipophilic non-coordinating (PF₆^? and BAr_F^?) and coordinating TRISPHAT-N^? anions are reported. Complex [CpRu(η⁶-naphthalene)][BAr_F] ([1][BAr_F]) is readily accessible, in high yield, by direct counterion exchange between [1][PF₆] and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBAr_F) salts. Ligand exchange of [1][BAr_F] in acetonitrile generated stable [Ru(η⁵-C₅H₅)(CH₃CN)₃][BAr_F] ([2][BAr_F]) complex in high yield. Then, the desired [CpRu(Phen)(CH₃CN)] ([3]) complexes were obtained from either the [1] or [2] complex in the presence of the 1,10-phenanthroline as ligand. For characterization and comparison purposes, the anionic hemilabile ligand TRISPHAT?N (TTN) was introduced on the ruthenium center, from the complex [3][PF₆], to quantitatively generate the desired complex [CpRu(Phen)(TTN)] ([4]) by displacement of the remaining acetonitrile ligand and of the PF₆^? anion. Solid state structures of complexes [1][BAr_F], [2][BAr_F], [3][BAr_F], [3][PF₆] and [4] were determined by X-ray diffraction studies and are discussed herein.

Full text of DOI:10.1002/hlca.202000190

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Accepted Article
Title: Preparation and structural characterization of [CpRu(1,10-
phenanthroline)(CH3CN)][X] and precursor complexes (X= PF6,
BArF, TRISPHAT-N)
Authors: Thierry Achard, Léo Egger, Cecilia Tortoreto, Laure Guenée,
and Jerome Lacour
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10.1002/hlca.202000190
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Preparation and structural characterization of [CpRu(1,10-
phenanthroline)(CH3CN)][X] and precursor complexes (X= PF6, BArF, TRISPHAT-N)
Thierry Achard,a Léo Egger,a Cecilia Tortoreto,a Laure Guénée,b Jérôme Lacour *,a
a Département de Chimie Organique, Université de Genève, quai Ernest Ansermet 30, 1211 Geneva 4 (Switzerland), jerome.lacour@unige.ch
b Laboratoire de Cristallographie, Université de Genève, quai Ernest Ansermet 24, 1211 Geneva 4 (Switzerland)
Dedicated to Antonio Togni
Cationic [Ru(η5-C5H5)(CH3CN)3]+ complex, tris(acetonitrile)(cyclopentadienyl)ruthenium(II), gives rise to a very rich organometallic chemistry. Combined with
diimine ligands, and 1,10-phenanthroline in particular, this system efficiently catalyzes diazo decomposition processes to generate metal-carbenes which
undergo a series of original transformations in the presence of Lewis basic substrates. Herein, syntheses and characterizations of [CpRu(Phen)(L)] complexes
−
−
with (large) lipophilic non-coordinating (PF6 and BArF ) and coordinating N-TRISPHAT− anions are reported. Complex [CpRu(η6-naphthalene)][BArF] [1][BArF]
is readily accessible, in high yield, by direct counterion exchange between [1][PF6] and sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (NaBArF) salts.
Ligand exchange of [1][BArF] in acetonitrile generated stable [Ru(η5-C5H5)(CH3CN)3][BArF] [2][BArF] complex in high yield. Then, the desired
[CpRu(Phen)(CH3CN)] [3] complexes were obtained from either the [1] or [2] complex in the presence of the 1,10-phenanthroline as ligand. For
characterization and comparison purposes, the anionic hemilabile ligand TRISPHAT-N (TTN) was introduced on the ruthenium center, from the complex
[3][PF6], to quantitatively generate the desired complex [CpRu(Phen)(TTN)] [4] by displacement of the remaining acetonitrile ligand and of the PF6− anion.
Solid state structures of complexes [1][BArF], [2][BArF], [3][BArF], [3][PF6] and [4] were determined by X-ray diffraction studies and are discussed herein.
Keywords: Ruthenium • Cyclopentadienyl • Catalysis • Solid-state
Introduction
Since its discovery by Gill and Mann in 1982, the cationic [(η5-C5H5)Ru(CH3CN)3] complex, commonly written [CpRu(CH3CN)3]+, has proven to be a powerful
building block in organometallic chemistry.[1-7] In fact, the CpRu fragment, and its Cp*Ru analogue, are recognized as effective catalysts for the promotion
of many versatile synthetic transformations.[4, 5, 8-12] Of importance for the current study, combinations of [CpRu] and nitrogen-based ligands[1, 3, 13, 14] such
as diimines[15-26] were also found to catalyze original processes.[7, 27, 28] For example, [CpRu(CH3CN)3][PF6] and pyridine-imine/pyridine-oxazoline ligands are
effective catalysts in enantioselective decarboxylative rearrangements of allylic β-ketoesters and carbonates.[26] [29-32]
Kitamura successfully applied
,
enantiopure dipyrroloimidazole ligands and [CpRu] in enantioselective dehydrative C-, N-, and O-allylation.[14, 33, 34] CpRu(bipyridine) complexes were shown
to be active catalysts for both deoxygenation of 1,2-hexanediol and glycerol[35] and hydrogenation of ketone in acidic conditions.[36] Previously, Herzon et
al. described the efficient anti-Markovnikov hydration of alkynes catalyze by [CpRu(N^N)] (N^N = diimine ligand) derivatives.[37-39]
Of interest in our laboratory, the [CpRu] fragment is also an interesting alternative to transition metal salts and complexes for the decomposition of diazo
derivatives providing metal carbene or carbenoid intermediates upon dinitrogen extrusion.[40-45] In fact, in the presence of combinations of
[CpRu(CH3CN)3][PF6] (as pre-catalysts) and diimine ligands (Phen = 1,10-phenanthroline, in particular) ,[8, 46, 47] α-diazo-β-ketoesters react smoothly and
provide selective 1,3-C-H insertions into THF[48] and O-H insertions into alcohols. This catalytic system also promotes condensation reactions with nitriles,
ketones, aldehydes and more recently with lactones and cyclic carbonates to generate the corresponding heterocycles (Scheme 1).[49, 50] Finally, in recent
studies, regio and syn-stereoselective three-atoms insertions into a large variety of epoxides and oxetanes were described leading to the formation of
original 1,4-dioxene and 1,4-dioxepine motifs respectively with, as pre-catalyst, the [CpRu(CH3CN)3][BArF] (BArF = tetrakis[3,5-
bis(trifluoromethyl)phenyl]borate) specifically.[51, 52] In view of the influence played by the BArF or PF6 anion nature onto the [CpRu] reactivity [44] but also,
more generally, of the importance of negative counterions in catalysis,[53-55] care was then taken to determine the structural impact associated such
gegenions onto [CpRu(1,10-phenanthroline)(CH3CN)][X] and precursor complexes.[56]
1
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Scheme 1. One-pot reactions of α-diazoacetoacetates and Lewis bases catalyzed by [CpRu][X] which stands for [CpRu(Phen)CH3CN][X] complexes (X= PF6 (blue), BArF (red)).
Results and Discussion
Cationic [CpRu(η6-naphthalene)]+ [1] (naphthalene = Naph), a practical and general precursor popularized by E. Peter Kündig for the formation of complex
−
−
−
[CpRu(CH3CN)3]+ [2], is readily accessible with an array of negative counterions, such as Cl−, CF3SO3 , SbF6−, PF6 or BF4 .[57] However and unfortunately,
previous attempts to perform anion metathesis of chloride to BArF by a direct exchange of [CpRu(η6-naphthalene)][Cl] with NaBArF, were not met with
success.[57] This problem could be circumvented in our hands starting from the [CpRu(η6-naphthalene)][PF6] salt instead which was prepared following
microwave assisted protocols.[57, 58] In practice, a simple mixing for 30 min of NaBArF and [1][PF6] in a homogenous dichloromethane/acetone solution (1.2/1)
provided, after crystallization from dichloromethane and hexane at 4 °C, the desired [CpRu(η6-naphthalene)][BArF] complex namely [1][BArF] in good yield
(72%, Scheme 2). The obtained yellow crystals were furthermore suitable for X-ray diffraction analysis, selected bond lengths and angles are given in Table
1.
Scheme 2. Anion metathesis from PF6− to BArF−; X-ray structure of [1][BArF]. Thermal ellipsoids are drawn at 50 % probability level and hydrogen atoms omitted for clarity.
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[59]
[60]
The Ru···Cp distance of 1.811 Å in complex [1][BArF] is similar that observed for [1][PF6]
and [1][TRISPHAT]
complexes (TRISPHAT =
Tris(tetrachlorobenzenediolato)phosphate) but significantly shorter than the corresponding distance in [CpRu(benzene)][PF6] derivative (1.845 Å).[61, 62]
However, the Ru··· Naph distances 1.719, 1.717 and 1.725 for [1][PF6], [1][BArF] and [1][TRISPHAT] respectively, are longer than that reported for the
benzene complex highlighting the known higher lability of naphthalene.[62] As observed for other [1][X] complexes, the bond lengths of the two quaternary
carbons of the bicyclic ring were longer (0.05 Å) than other Ru-CNaphthalene bonds.[59],[60] The Ru-CCp (average 2.166 Å) in [1][BArF] is shorter than others reported
for [CpRu(η6-naphthalene)] complexes.[59],[60]
With precursors [CpRu(η6-naphthalene)][X] in hand (X = PF6, BArF),[1-3, 57, 63] targeted derivatives were readily prepared, thanks to the facile haptotropic 6→4
ring slippage of complexes [1] which allowed the straightforward displacement of the naphthalene ligand by acetonitrile molecules (Scheme 3).[57] At the
end of the reaction, the free naphthalene moiety was simply removed by extraction of the acetonitrile solution with dry hexane to afford, after evaporation
of the acetonitrile, yellow complexes [2][PF6] and [2][BArF] in quantitative yield.[64] Slow diffusion of hexane in a solution of [2][BArF] in methylene chloride
at 4 °C for 3 days yielded suitable crystals for X-ray diffraction analysis (Scheme 3). The Ru···Cp distance of 1.779 Å in complex [2][BArF] is found slightly
shorter compared to [1][BArF]. The three Ru-acetonitrile (AN) bonds are not completely equivalent but their bond distances are in the same range around
2.08-2.09 Å. These differences in the solid state can be explained by the spatial proximity of the acetonitrile moieties to the BArF anion(s) in the crystal unit
−
cell. It was found that the presence of BArF as counterion strongly reduces the oxygen and moisture sensitivity of the [CpRu(CH3CN)3]+ fragment compared
to its PF6− analogue which decomposes under air after a few days only. In addition, the acetonitrile moieties are labile in their own right and this behavior
has been strongly exploited to prepare further [CpRu] derivatives under mild conditions.[1-3, 65-78]
Scheme 3. Synthesis of [CpRu(CH3CN)3][X]; X-ray structure of [2][BArF]. Thermal ellipsoids are drawn at 50 % probability level and hydrogen atoms omitted for clarity.
In our case, care was taken to utilize 1,10-phenanthroline (Phen) as a model diimine ligand, and the resulting complexes [3][X] were generated either directly
from [CpRu(η6-naphthalene)][X] or via the intermediacy of [CpRu(CH3CN)3][X] in acetonitrile solutions. Experimentally, 1 equiv of 1,10-phenanthroline was
added to a dichloromethane solution of the desired [2] complex and the resulting purple mixture was stirred at room temperature under argon. Reaction
completion was achieved within 2-4 hours affording the corresponding [3][X] moiety (Scheme 4, path a).[79] Practically, these ligand exchange steps can be
combined into a single sequential process using acetonitrile as the single solvent. However, in this case, the coordination of 1,10-phenanthroline to the
ruthenium center is slower due to the direct competition with coordinating acetonitrile solvent molecules (Scheme 4, paths b and c).[80] In each case, the
dark purple solution was evaporated to dryness and the crude mixture was allowed to recrystallize in dichloromethane/hexane to afford complex [3][PF6] in
a high yield of 92%. Dark red X-ray quality crystals were further obtained by slow diffusion of hexane in a THF solution of [3][PF6] at 4 °C for 3 days and a
structural analysis was performed (Scheme 4). Selected bond lengths and angles are given in Table 1. Complex [3][BArF] was synthesized using the same
ligand exchange procedure giving after recrystallization, in a 1:3 mixture of hexane:dichlorometane, dark red crystals in 98% yield. Selected bond lengths
and angles are given in Table 1 as well.
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Scheme 4. Synthesis of [CpRu(CH3CN)3][X] and [CpRu(1,10-Phenanthroline)(CH3CN)3][X] complexes (X = PF6, BArF), salts [2][X] and [3][X] respectively. ORTEP views of [3][PF6] and
[3][BArF]. Thermal ellipsoids are drawn at 50 % probability level. Hydrogen atoms are omitted for clarity.
Table 1. Selected bond lengths (Å) and angles (deg) for CpRu complexes 1 to 4 with estimated standard deviations in parentheses.[a]
Bond lengths /angles
[1][BArF]
[2][BArF]
[3][PF6]
[3][BArF]
[4]
Ru-N1Phen
Ru-N2Phen
Ru-N3AN
Ru-NTTN
Ru-P
-
-
2.105(3)
2.104(3)
2.109(4)
-
-
2.106(3)
2.101(3)
2.088(4)
-
2.081; 2.089; 2.090(3)
2.074(3)
2.074(3)
-
-
-
-
-
2.150(4)
-
-
6.281(1)
-
4.872(1)
Ru-B
8.324(4)
2.151(6)
2.158(6)
2.167(5)
2.178(6)
2.182(5)
2.198(5)
2.202(5)
2.208(5)
2.213(5)
2.261(4)
2.267(4)
-
9.721(3)
-
7.890(4)
-
Ru-CCp
2.138(4)
2.152(4)
2.163(4)
2.175(4)
Ru-CCp
2.143(4)
2.137(4)
2.146(4)
2.155(5)
Ru-CCp
2.151(4)
2.151(4)
2.141(4)
2.160(5)
Ru-CCp
2.152(4)
2.156(4)
2.152(4)
2.144(4)
Ru-CCp
2.152(4)
2.178(4)
2.154(4)
2.133(5)
Ru-CNaph
Ru-CNaph
Ru-CNaph
Ru-CNaph
Ru-CNaph
Ru-CNaph
N1-Ru-N2
N2-Ru-N3
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
77.2(1)
85.9(1)
77.4(1)
87.2(1)
77.9(2)
85.8(1)
-
[a] AN = acetonitrile, Cp = cyclopentadiene; Naph = naphthalene, TTN = Trisphat-N
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Previously, our group reported the synthesis and the resolution of hexacoordinated phosphorus(V) TRISPHAT-N anion (TRISPHAT-N = Bis[3,4,5,6-
tetrachlorobenzene-1,2-diolato][5-chloropyridine-2,3-diolato]phosphate).[81] This chiral anion, owing to the presence of a Lewis basic pyridine moiety in
the framework, has the ability to coordinate to metal centers; previous studies demonstrating an allied hemi-lability.[81, 82] Furthermore, an important
lipophilicity is given by the phosphate skeleton which then allows the ready chromatographic isolation and separation of zwitterionic adducts. In practice,
counter ion exchange took place in dichloromethane using the isolated [3][PF6] complex and racemic [n-Bu3NH][TRISPHAT-N] salt which generated, in one
hour, the desired [CpRu(phen)(TRISPHAT-N)], or [CpRu(phen)(TTN)] [4] complex. Alternatively, a complete one-pot reaction could be reached in 3 h only by
simply mixing an equimolar amounts of [CpRu(CH3CN)3][PF6], 1,10-phenanthroline and [n-Bu3NH][TRISPHAT-N] (Scheme 5). In each case, the compound
was purified by column chromatography (Rf 0.98 in methylene chloride) to give a red solid in good yield (80%). Noteworthy, when attempted, the direct
anion exchange metathesis between lipophilic TTN− and BArF− failed, complex [3][BArF] being totally recovered at the end of the reaction. Gratifyingly, the
desired air and moisture stable [4] complex was found to be moderately soluble in dichloromethane/pentane at −20 °C. X-Ray quality crystals were
obtained and a structural analysis was performed (Scheme 5).
Scheme 5. Synthesis and ORTEP view of [CpRu(phen)(TTN)] [4] complex. Thermal ellipsoids are drawn at 50 % probability level. Hydrogen atoms are omitted for clarity.
These X-ray structural analyses indicated that the ruthenium atom is π-coordinated to the C5H5 ring and in a σ mode to N donor bidentate phenanthroline
and to an acetonitrile fragment in a piano stool mode (Schemes 3 and 4). The average Ru-N bond length of 2.104 Å for complexes [3][PF6] and [3][BArF] is
in agreement with values for reported piano stool CpRu(N^N) complexes with, for example, an average of ~2.095 Å for [CpRu(bipy)(CH3CN)][OTf].[35] These
values highlight the σ-donor character of the 1,10-Phenanthroline ligand. Similarly, the Ru-NC-Me bond length average of 2.074 Å is in line with other Ru-
NC-Me complexes (2.071 Å).[35, 36, 66, 83-85]
The Ru-CCp distances are in the range of 2.137–2.178 Å and their average (2.153 Å) agrees with those reported for [CpRu(bipy)(CH3CN)][OTf] cationic
complex.[35] The Ru-Cp distance, in which Cp is the Cp centroid, for complex [PF6] is 1.793 Å, and hence comparable to that of 1.791 Å observed for
CpRu(bipy) complex. Curiously, both non-coordinating [BArF] and coordinating anion [TTN] showed slightly shorter distances of 1.784 and 1.781
respectively. However, the symmetry breakage in [4] caused by the coordination of TRISPHAT-N through the ruthenium center has an effect on the σ-bond
lengths as Ru-N1 (2.109 Å) and Ru-N2 (2.088 Å) are not equivalent anymore (Scheme 5).
As already mentioned, it has been established that the nature of anionic counterions play a crucial role in catalysis.[86] Interactions between cationic and
anionic partners can strongly affect the solubility of resulting catalysts, the rate and the selectivity of reactions or even change its course.[84, 87-97] For years
5
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it was assumed that anions such as BF4−, PF6− and SbF6− were non-coordinating, but now there are better described as “weakly coordinating anion”
(WCA).[98-102] However, previous investigations have shown that these anions are able to interact with cations either directly or through hydrogen
bonds.[103-107] To take into account the possible occurrence of such interactions, careful analyses of hydrogen and fluorine contacts were monitored in both
solid state (X-ray) and in solution (NMR 1H-19F HOESY experiments). In the X-ray structure packing of [3][PF6], hexafluorophosphate anions were showed to
interact via H ··· F interactions not only with the hydrogen atoms of acetonitrile ligands but also with that of the Cp ring (H ··· F <3Å, Table 2). The solid
state structure of complex [3][BArF] was also investigated and once again, relatively short contact between fluorine atoms and both acetonitrile and Cp
ligands (2.6-3.0 Å, Table 2) could be found. Lastly, the greater distance between the (formally) positively charged ruthenium and negatively charged boron
atoms in [3][BArF] (Ru···B : 7.89 Å) advocates in fine for a stronger Lewis acidic metal coordination site which, in retrospect, might provide higher catalyst
turnover frequency for the BArF− salt as compared to complex [3][PF6] for which the anion/cation pair seems to be tighter (Ru···P : 6.28 Å). The augmented
distance of this anion from the Lewis acid reactive site would have two main possible effects, (i) an increased Lewis acidity which should promote the
nucleophilic attack of the diazo reagents and thus favor for the formation of the carbene intermediates, (ii) a possible decrease in coordination
competition between anion and substrate, which could also favor an increase in reaction rates as reported for other CpRu catalysts.[56],[108]
In solution, 1H-19F HOESY spectra were measured in deuterated dichloromethane for both [3][PF6] and [3][BArF] salts. In both instances, signals
corresponding to NOE interactions between the anions and bound acetonitrile and Cp ligands could not be observed. In accordance with other studies in
moderately dissociative solvents like CD2Cl2,[84] these results suggest that both PF6− and BArF− anions are not strongly paired with [CpRu] fragments in such
solutions. The lack of crystallographic literature data for [(Phen)CpRu(CH3CN)][X] salts containing more coordinating anions (X = OTf or BF4) renders difficult
to conclude in such cases. However, comparison of the Ru---B distances in complexes [2][BArF] and [CpRu(CH3CN)3][BF4],[109] with respectively 9.721Å and
5.885Å, shows a large difference (ΔÅ = 3.836 Å) which is expected to impact the reactivity.[56]
Table 2. Selected bonds lengths [Å] and angles [deg] for complexes [3] with estimated standard deviations in parentheses.
C-H···F Hydrogen Bonds interactions (Å)
C-H···F
H···F
C···F
C-H···F
[3][PF6]
C14-H··· F4
C16-H··· F1’ [a]
NC19-H···F3’’ [a]
NC19-H···F6’’ [a]
[3][BArF]
3.041(4)
2.544(5)
2.667(4)
2.588(4)
3.884(6)
3.224(7)
3.642(6)
3.366(6)
148.8(2)
128.6(3)
173.1(2)
136.4(3)
C15-H···F20
C16-H···F20
NC19-H···F7
2.614(4)
3.051(5)
2.611(5)
3.266(6)
3.469(7)
3.208(6)
126.2(3)
108.3(3)
119.4(3)
[a] Fluorine atom from a symmetry equivalent molecule of PF6 in the crystal packing (’) -1+x, y, z and (‘’) 1-x, -y,1-z.
Conclusions
In summary, the synthesis and X-ray structural analyses of [CpRu(Phen)] fragments combined with large lipophilic PF6−, BArF− and TRISPHAT-N anions were
achieved. Starting with the air-stable [CpRu(η6-naphthalene)][PF6] precursor, complex [CpRu(η6-naphthalene)][BArF] was prepared on multigram scale
through simple ion exchange metathesis from the PF6− salt. Corresponding [CpRu(CH3CN)3][X] complexes (X = PF6, BArF) were generated in acetonitrile, and
subsequently used for ligand exchange reaction to afford [CpRu(Phen)CH3CN][X] salts in high yield from isolated [2][X] precursors. In CH2Cl2, hemi-labile
TRISPHAT-N anion easily displaced the last acetonitrile ligand of derivatives [3][X] to form air stable complex [4], readily purified by chromatography. Care
was also taken to study the nature of the solution and solid-state interactions occurring among combinations of CpRu fragments and Phen ligand on one
−
−
hand, and PF6 , BArF and TRISPHAT-N− anions on the other. Investigations by 1H-19F HOESY spectroscopy in solution and solid-state X-ray measurements
did not indicate any significant ion pairing within both PF6− and BArF− salts. This lack of severe ion pairing constraint is in accordance with the catalytic
properties of these derivatives, which allow the facile decomposition of α-diazo-β-ketoesters and subsequent transformations of the derived metal
carbenes.
6
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Experimental Section
The dataset for this article can be found at the following DOI: 10.26037/yareta:rnzaplk6k5c7fmyb55l366gope. It will be preserved for 10 years. Synthetic
procedures and spectral characterization of new compounds are reported in the electronic supporting information. CCDC-2026525 to 2026529 contain the
supplementary crystallographic data for this work. These data can be obtained free of charge from The Cambridge Crystallographic Data Centre via
www.ccdc.cam.ac.uk/data_request/cif.
Acknowledgements
We thank the University of Geneva and the Swiss National Science Foundation for financial support. We acknowledge the contributions of the Sciences
Mass Spectrometry (SMS) platform at the Faculty of Sciences, University of Geneva. We also thank Júlia Viñas Lóbez, Guillaume Levitre and Romain
Pertschi for proofreading the manuscript and Romain Pertschi for the addition of the accelerated procedure for the trisacetonitrile complex synthesis.
Author Contribution Statement
T. A., L. E. and C. T. performed the experiments and characterization of all materials and co-wrote the manuscript. L. G. performed the X-ray diffraction
studies and co-wrote sections dedicated to solid-state analyses. J. L supervised the work and wrote the manuscript. All authors commented on the manuscript.
References
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synthetically useful intermediate: the cyclopentadienyltris(acetonitrile)ruthenium(II) cation’, Organometallics 1982, 1, 485-488.
C. Slugovc, E. Rüba, R. Schmid, K. Kirchner, K. Mereiter, ‘Recent Chemistry Based on the [RuCp(CH3CN)3]+ Cation: Reappraisal of an Old
Precursor’, Monatsh. Chem. 2000, 131, 1241-1251.
[3]
[4]
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10.1002/hlca.202000190
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Combinations of [CpRu(CH3CN)3] salts and phen ligands are catalysts for diazo decomposition and subsequent carbene reactivity. Ru(II)
precursors and phen complexes are characterized in solution and solid-state.
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