Dinuclear and mononuclear chromium acetylide complexes

Article abstract of DOI:10.1002/ejic.201100929

Reaction of trans-Cl₂Cr(dmpe)₂ (1) [dmpe = 1,2-bis(dimethylphosphanyl)ethane] with 0.5 equiv. of Me₃Sn-C=C-C=C- SnMe₃ or Me₃Sn-C=C-C₆H₄-C=C- SnMe₃ afforded the dinucle

Full text of DOI:10.1002/ejic.201100929

FULL PAPER
DOI: 10.1002/ejic.201100929
Dinuclear and Mononuclear Chromium Acetylide Complexes
Carolina Egler-Lucas,[a] Olivier Blacque,[a] Koushik Venkatesan,[a]
Alberto López-Hernández,[a] and Heinz Berke*[a]
Dedicated to Professor Gerhard Erker on the occasion of his 65th birthday
Keywords: Chromium / Cyclic voltammetry / Molecular electronics / Alkynes
Reaction of trans-Cl2Cr(dmpe)2 (1) [dmpe = 1,2-bis(dimethyl-
phosphanyl)ethane] with 0.5 equiv. of Me3Sn–CϵC–CϵC–
SnMe3 or Me3Sn–CϵC–C6H4–CϵC–SnMe3 afforded the di-
nuclear complexes trans-[Cl(dmpe)2CrϵC–CϵC–CϵCr-
(dmpe)2Cl] (2), trans-[Cl(dmpe)2Cr–CϵC–CϵC–Cr(dmpe)2-
Cl][SnMe3Cl2]2 (2[SnMe3Cl2]2), and trans-[Cl(dmpe)2Cr–
CϵC–C6H4–CϵC–Cr(dmpe)2Cl][SnMe3Cl2]2 (3[SnMe3Cl2]2),
which could be transformed to the 2[PF6]2 and 3[BPh4]2 salts.
Substitutions of the chloride groups in 2 were carried out to
achieve the corresponding iodo (4) and (trimethylsilyl)alk-
ynyl (5) complexes. Utilizing similar reactions and treatment
with only 1 equiv. of the corresponding alkynyl ligand
[Me3Sn–CϵC–R (R = –SnMe3, –C6H5), Me3Sn–CϵC–CϵC–R
(R = –SiMe3, –SnMe3), and Me3Sn–CϵC–C6H4–CϵC–SnMe3]
allowed us to prepare a series of mononuclear monoacetylide
complexes: trans-[Cl(dmpe)2Cr–CϵC–R] [R = –SnMe3(6),
–C6H5(7)], trans-[Cl(dmpe)2Cr–CϵC–CϵC–R] [R = –SiMe3(8),
–SnMe3(9)], and trans-[Cl(dmpe)2Cr–CϵC–C6H4–CϵC–
SnMe3] (10), respectively. The complexes 2, 2[SnMe3Cl2]2,
2[PF6]2, 3[SnMe3Cl2]2, 3[BPh4]2, and 6–10 displayed para-
magnetic behavior. Electrochemical studies performed on the
dinuclear complexes (2), (2[SnMe3Cl2]2), (3[SnMe3Cl2]2), and
(5) showed one two-electron redox wave revealing a class-I
type behavior based on the Robin–Day classification, which
is untypical for dinuclear complexes bridged by a butadiyne
ligand. The complexes were characterized by NMR, ESI–MS,
cyclic voltammetry, EPR spectroscopy, magnetic measure-
ments, and exemplary single-crystal X-ray diffraction studies
for 2, 2[SnMe3Cl2]2, 8, 9, and 10.
candidates for the construction of molecular wires. They
were in addition extensively investigated to explore their
physical properties.[8–10] Homo- or heterometallic com-
plexes in which unsaturated elemental-carbon chains span
two metals of the type LmMCnMЈLЈm were thus re-
ported[11,12] and turned out to be especially suited for the
study of the electronic interaction between the two metal
centers.[13–17] These complexes constitute the most funda-
mental class of carbon-based rigid-rod-type molecular
wires,[18,19] and represent attractive synthetic targets that al-
low the study of their electronic, optical, and electrochemi-
cal properties.[20]
Among the known bimetallic complexes most of them
are bismetallocene complexes.[21] One of the disadvantages
associated with this type of compound is that the coordina-
tion sphere does not allow any further substitution thereby
acting as a stopper unit to the wire. Complexes of the type
LmMCnMЈLЈm with n = 4 have been reported for M =
Fe,[22,23] Re,[12,24–26] Ru,[27] Pt,[28] Mo,[29,30] Mn,[31–33] Os,[34]
and the most recent for W.[35] These kinds of complexes
normally reveal high delocalization of the electrons. Metal
complexes belonging to class-III compounds, based on the
Robin–Day classification of electron transfer, are consid-
ered as good candidates for the construction of molecular
Introduction
Over the last two decades organometallic complexes
bridged by acetylenic units were investigated as rigid-rod
redox-active complexes denoted as molecular wires. On the
basis of through-bridge single-electron conductivity they
show potential for applications in the field of molecular
electronics.[1–3] Organic molecular wires studied to date
were constructed entirely of delocalized orbital systems.
However, they often revealed lower molecular single-elec-
tron conductivities than that predicted theoretically.[4,5] The
incorporation of transition-metal centers in these chains
was found to increase the delocalization due to the strong
electronic coupling between the metal center and the conju-
gated organic ligands.[6,7] The electronic properties of mo-
lecular wires built from organometallic complexes can be
fine-tuned by modifying the extent of conjugation in the
bridge or changing the metal center or by switching the
oxidation states of the metal. Bridged or terminal ligands
based on linear Cn polycarbon chains emerged as important
[a] Institute of Inorganic Chemistry, University of Zürich,
Winterthurerstrasse 190, 8057 Zürich, Switzerland
Fax: +41-44-635-4806
E-mail: hberke@aci.uzh.ch
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Dinuclear and Mononuclear Chromium Acetylide Complexes
wires, possessing no or almost no barrier for electron trans- and properties of the dinuclear chromium complexes pos-
fer.[36] On the other hand compounds corresponding to sessing a butadiyne bridge and exhibiting an unusual class-
class I or II are expected to show barriers for electron trans- I behavior based on the Robin–Day classification,[40] and
fer that make these complexes useful for controlling the ex- mononuclear chromium monoacetylide complexes with tri-
tent of electron-transfer functions and to serve for instance methylstannyl end groups.
as resistors, diodes, or single-electron transistors.
We have recently reported investigations on dinuclear bu-
tadiyne tungsten carbyne complexes and further their func-
tionalization of the terminal ends with Fe(depe)2Cl caps
Results and Discussion
[depe = 1,2-bis(diethylphosphanyl)ethane]. In continuation
Substitution reactions of the Cl2Cr(dmpe)2 complex with
with the ongoing investigations in our group, chromium lithium acetylides to form bis(acetylide) complexes were in-
based dinuclear butadiyne complexes were also expected to vestigated earlier in our group,[38] however similar condi-
possess appropriate energy–work functions suitable for the tions could not be adopted for the synthesis of the mono-
construction of molecular wires. The first chromium com- substituted alkyne complexes and the dinuclear butadiyne
plexes bearing the chelating ligand 1,2-bis(dimethylphos- complexes. Hence, a different synthetic strategy was sought
phanyl)ethane (dmpe) was reported by Wilkinson and co- that involved the use of trimethylstannyl alkynyl reagents
workers,[37] and several chromium bis(acetylide) complexes with the starting Cl2Cr(dmpe)2 complex. The dinuclear
using these chelating phosphane ligands were previously complexes 2, 2[SnMe3Cl2]2, and 3[SnMe3Cl2]2 were ob-
prepared by our group.[38] In this context a dinuclear bis- tained by heating Cl2Cr(dmpe)2[37] with 0.5 equiv. of bis(tri-
(acetylide)-chromium(I) complex bridged by a dinitrogen li- methylstannyl)butadiyne (Scheme 1) in benzene for 12 h at
gand has been reported.[39] The synthesis of the monoace- 80 °C. An anion exchange was performed for 2[SnMe3Cl2]2
tylide complexes would create a new set of building blocks by treatment with a stoichiometric amount of NaPF6 in
for heterodinuclear compounds after coupling these mono- CH2Cl2 to form the corresponding salt 2[PF6]2. In order to
substituted species with different metal precursors contain- obtain the neutral complex 2, the reaction was carried out
ing Fe, Re, or W. In this work, we report on the syntheses in the presence of Zn powder as a reducing agent and the
Scheme 1.
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H. Berke et al.
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corresponding neutral complex was obtained in 55% yield.
However, using this route we were only able to obtain the
dicationic complex 3[SnMe3Cl2]2 when Me3Sn–CϵC–
C6H4–CϵC–SnMe3 was used. An anion exchange was per-
formed on complex 3[SnMe3Cl2]2, as well, to form the cor-
responding 3[BPh4]2 by treatment with a stoichiometric
amount of NaBPh4 in acetonitrile.
Strong paramagnetic behavior for the complexes
2[SnMe3Cl2]2, 2[PF6]2, 3[SnMe3Cl2]2, and 3[BPh4]2 was ob-
served in the 1H NMR and 31P NMR spectra. The 1H
NMR resonances of these complexes appeared at high field
Figure 2. Crystal structure of 2 (ellipsoids set at the 50% prob-
as broad signals at –14.5 and –33.7 ppm for the methylene ability level). The hydrogen atoms are omitted for clarity. Selected
bond lengths [Å] and angles [°]: Cr1–Cl1 2.4107(9), Cr1–C1
and methyl protons, respectively.
1.789(3), C1–C2 1.301(4), C2–C2Ј 1.286(4), Cr1–P1 2.325(1), Cr1–
A study of the Curie–Weiss behavior using a temperature
P2 2.3350(9), Cr1–P3 2.322(1), Cr1–P4 2.315(1), Cr1–C1–C2
177.2(2), C1–C2–C2Ј 176.9(3).
range between 30 °C and –70 °C was carried out to confirm
the paramagnetic character of 2[SnMe3Cl2]2 (Figure 1). The
resonances (PCH2 and PCH3) for the dmpe ligand showed
a shift from –19.6 to –14.7 ppm over the temperature range
from 30 °C to –70 °C.
Figure 3. Crystal structure of 2[SnMe3Cl2]2 (ellipsoids set at the
50% probability level). The hydrogen atoms are omitted for clarity.
Selected bond lengths [Å] and angles [°]: Cr1–Cl1 2.328(1), Cr1–
C1 1.951(3), C1–C2 1.218(5), C2–C2Ј 1.377(5), Cr1–P1 2.441(1),
Cr1–P2 2.427(2), Cr1–P3 2.443(1), Cr1–P4 2.435(2), Cr1–C1–C2
177.0(4), C1–C2–C2Ј 179.4(5).
Figure 1. Curie–Weiss behavior for the proton resonances of and 1.377(5) Å, respectively, confirming the C4 chain of
2[SnMe3Cl2]2 as prevailingly bisacetylenic.[42,45] This clearly
2[SnMe3Cl2]2 in CD2Cl2 over a temperature range from 30 °C to
–70 °C (R = 0.990).
indicates that the oxidation of 2 causes a transformation of
the C4 bridge, from biscarbynic to bisacetylenic, and as a
1
The H NMR spectrum of 2 exhibits signals at δ = 1.3
consequence the electronic configuration of the complex
and 1.6 ppm for the methylene protons and the methyl pro-
tons of the dmpe ligands, respectively. In the IR spectra
changes from an 18e– complex to a 15e– complex.
these chromium complexes reveal bands at ν ≈ 2050 and
˜
2000 cm–1 for 2, ν ≈ 1990 and 1940 cm–1 for 2[SnMe3Cl2]2,
˜
and at 1950 and 1580 cm–1 for 3[SnMe3Cl2]2; these varia-
tions correspond to different vibrations of the C4 chain.[41]
The structures of 2 (Figure 2) and 2[SnMe3Cl2]2 (Figure 3)
were confirmed by X-ray diffraction studies. In both mole-
Scheme 2. Canonical forms of a C4 unit in [M]C4[M] structures.
Electrochemical studies of the complexes 2, 2[SnMe3-
cules the ligand geometry around the chromium atoms are Cl2]2, and 3[SnMe3Cl2]2 (Figure 4) were employed to evalu-
approximately octahedral with the Cl and the butadiyne li- ate the abilities of electronic communication between the
gand in the trans positions and the P atoms in an equatorial chromium centers. All complexes displayed one reversible
arrangement displaying Cr–P distances between 2.315(1) two-electron redox wave with E1/2 at –1.08 V (2), –1.20 V
and 2.443(1) Å.
(2[SnMe3Cl2]2), and –1.29 V (3[SnMe3Cl2]2). This behavior
The Cα–Cβ bond lengths are longer than the central Cβ– is in contrast to that observed in related W–C4–W com-
CβЈ distance of 2 and the Cr–Cα bond length is close to plexes. Also the redox potentials are significantly lower
that of a triple bond[42] confirming a biscarbyne canonical than that observed for the tungsten complexes, which are at
0/+ [35]
structure (Scheme 2).[42–44] In the case of complex –0.253 and –0.543 V vs. Fc
.
The presence of only one
2[SnMe3Cl2]2 the Cα–Cβ and Cβ–CβЈ distances are 1.218(5) redox wave for the chromium complexes corresponds to the
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Dinuclear and Mononuclear Chromium Acetylide Complexes
kind of behavior expected for a class-I system according
The magnetic susceptibility curve of 2[SnMe3Cl2]2 (Fig-
to the Robin–Day classification (localized).[40] For class-I ure 5) shows the typical paramagnetic behavior of a d3
complexes, the barrier to electron transfer is very high, such high-spin complex, with a magnetic moment of 2.19 μB,
1
that electrons are permanently “locked” in one position,[46] which further confirms the observation from the H NMR
and the properties of these systems are essentially those of spectroscopy of a temperature-dependent paramagnetic
the separate sites.[47] Mixed-valent complexes of this type of left-shift behavior. The EPR spectrum of 2[PF6]2 in CH2Cl2
dinuclear complex are often not stable since they tend to at 6 K (Figure 6) showed one signal corresponding to the
disproportionate. As it was already discussed for a tungsten unpaired electron of the orbital dxy of the metal center. This
carbyne-type system, under rigorous symmetry conditions can be attributed to a strong antiferromagnetic coupling of
the HOMO is expected to be of δ-type and hence through the unpaired electrons of the dxz and dyz orbital of the chro-
bridge interactions from π orbitals are not possible. There- mium(III) centers through the bridge. A hyperfine coupling
fore, the electron transfer observed in a tungsten complex is detected because of the coupling with the phosphorus
is attributed to lowering of the symmetry of the molecule nuclei, but has not been resolved well enough to be quanti-
exemplified in the W–Cα–Cβ angle of 172° of the tungsten fied. Further EPR studies of 2 under the same conditions
carbyne chain.[35] Such a strong distortion is not observed showed EPR silent behavior.
in the chromium dinuclear complexes of this work where
the Cr–Cα–Cβ angle in the complexes was found to be ap-
proximately 177°. This could be a plausible reason for the
total absence of electronic interaction between the two
metal centers.
Figure 5. Temperature dependence of χ vs. T and 1/(χ – D) vs. T
(inset) for complex 2[SnMe3Cl2]2.
Figure 4. Cyclic voltammograms for 2, 2[SnMe3Cl2]2, and
3[SnMe3Cl2]2 in 0.1 m [nBu4N][PF6] (Au electrode, scan rate:
100 mVs–1 20 °C. E vs. Ag0/+).
Further confirmation of the class-I behavior was ob-
tained from the absence of an intervalence charge-transfer
band of a 1:1 mixture of complexes 2 and 2[SnMe3Cl2]2 in
CH2Cl2 in the NIR spectrum, which for class-III com-
pounds would be expected to comproportionate to a mixed-
valent species and for class-I compounds the equilibrium
would lie on the left side forming no mixed-valent species
at all (Scheme 3). It is important to mention that we could
not observe or isolate any mixed-valence complex, which
Figure 6. EPR of 2[PF6]2 in CH2Cl2 glass at 6 K.
would exclude the formation of a mixed-valent compound
(class-I).
In order to further elucidate the effect of the axial ligand
on the electronic properties of these chromium complexes,
a preparation for complexes with different electronic prop-
erties of these groups was sought (Scheme 4).
The iodo derivative 4 was obtained in a Finkelstein-type
reaction by stirring 20 equiv. of KI with 2 in THF. Such an
excess was probably required because of the low solubility
Scheme 3.
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H. Berke et al.
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Scheme 4.
of KI in THF. In the case of 5, substitution of the Cl group
The presence of the anion in complex 2[SnMe3Cl2]2 de-
could be achieved by using an excess of lithium trimethyl- creases the E1/2 value by about 123 mV in comparison with
silyl acetylide in THF at 60 °C for 12 h. The dinuclear spe- complex 2 and under CV conditions was oxidized to 2[PF6]2,
cies 4 and 5 were isolated in 70 and 67% yield, respectively. which could possibly arise from enhanced ion paring. Com-
Such end-group replacements of the halides with acetylide plex 2 with chloride end groups shows a higher redox
ligands open up possibilities for further functionalization of potential than 5 with acetylide end groups, which is consis-
the dinuclear complexes. Electrochemical studies were per- tent with the stronger σ-donating property of the acetylide
formed on 5. It exhibits a single redox wave at E1/2
=
ligands. In the case of complex 3[SnMe3Cl2]2 the difference
–1.21 V (Figure 7) corresponding to two electrons, similar in the ipa and ipc values (ΔEp = 560 mV) increases in com-
to the behavior already observed for the dinuclear com- parison with the complexes bearing the butadiyne bridge,
plexes 2, 2[SnMe3Cl2]2, and 3[SnMe3Cl2]2 (Table 1).
which is indicative of the decrease in the reversibility of the
process.[48] This is in agreement with results reported by
Gladysz et al., with different chain lengths for the rhenium
complexes.[19]
Since the electronic communication between the homo-
nuclear chromium complexes remained elusive, we thought
to eventually achieve one-way electronic communication by
preparation of heterodinuclear complexes. We previously
demonstrated that trimethylstannyl alkynes can be excellent
precursors for reactions with Fe(depe)2Cl2.[49] In this con-
text substitutions of the halides with trimethylstannyl alk-
ynes in the chromium complexes would indeed allow the
preparation of heteronuclear complexes.
A series of mononuclear monoacetylide complexes was
obtained by treatment of Cl2Cr(dmpe)2 with 1 equiv. of the
corresponding trimethylstannyl alkynyl reagent in benzene
at 80 °C for 12 h (Schemes 5 and 6). All these mononuclear
Figure 7. Cyclic voltammogram for 5 in 0.1 m [nBu4N][PF6] (Au
electrode, scan rate: 100 mVs–1, 20 °C. E vs. Ag0/+).
Table 1. Electrochemical data for complexes 2, 2[SnMe3Cl2]2,
3[SnMe3Cl2]2, and 5.
Complex
E1/2 [V]
ΔEp [mV]
2
–1.077
–1.200
–1.288
–1.209
115
228
560
152
2[SnMe3Cl2]2
3[SnMe3Cl2]2
5
Scheme 5.
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Dinuclear and Mononuclear Chromium Acetylide Complexes
Scheme 6.
complexes were obtained in good yields, except for the cases dination with the alkyne ligand and the Cl group in a trans
of 9 and 10 with SnMe3 end groups, where the yields were position. The Cr–Cα bond lengths in all complexes are close
lower than those of the other mononuclear complexes be- to 2 Å confirming the ligand structures as acetylides.
cause of the formation of small amounts of the dinuclear
complexes. In the case of 1,2-bis(trimethylstannyl)ethyne
(6), the formation of the corresponding C2 dinuclear com-
plex was not observed and this was attributed to a high
steric congestion of the ligands. In the IR spectrum of 6–
10 the characteristic bands for the (CϵC) vibrations were
observed at 2010–1950 cm–1 for the acetylene units and be-
tween 2900–2965 cm–1 for the C–H vibrations of the methyl
and methylene groups.
1
The H NMR spectra of 6–10 showed strong paramag-
netic behavior. Resonances at –13 and –30 ppm were ob-
Figure 9. Crystal structure of 9 (ellipsoids set at the 50% prob-
served for the methylene and methyl protons, respectively.
For 7 and 10 two broad signals were found at 33 and
–52 ppm corresponding to the aromatic protons. All the
complexes were additionally characterized by ESI–MS and
elemental analysis.
ability level). The hydrogen atoms are omitted for clarity. Selected
bond lengths [Å]: Cr1–Cl1 2.3632(14), Cr1–C13 1.995(5), C13–C14
1.229(8), C14–C15 1.364(8), C15–C16 1.199(9), C16–Sn1 2.115(5).
Cyclic voltammetry of 9 showed a reversible one-electron
redox wave at E1/2 = –1.339 V (ΔEp = 364 mV) correspond-
ing to the CrII/CrIII redox couple. The structures of 8–10
were confirmed by X-ray diffraction studies (see Figures 8,
9, and 10). The chromium centers possess octahedral coor-
Figure 10. Crystal structure of 10 (ellipsoids set at the 50% prob-
ability level). The hydrogen atoms are omitted for clarity. Selected
bond lengths [Å]: Cr1–Cl1 2.4042(11), Cr1–C1 2.000(4), C1–C2
1.224(6), C2–C3 1.432(6), C6–C9 1.418(6), C9–C10 1.208(6), C10–
Sn1 2.108(5).
The C16–Sn1 and C10–Sn1 distances in 9 and 10 are
2.115(7) and 2.108(5) Å, respectively. These distances are
longer than the C–Si distance of 1.8383(16) Å observed in
8 and in other mononuclear chromium acetylene deriva-
tives;[38] confirming the high reactivity of the Me3Sn end
group in comparison to the Me3Si end groups, which is con-
sistent with the lower dissociation energy of the C–Sn
bond.[50]
Figure 8. Crystal structure of 8 (ellipsoids set at the 50% prob-
ability level). The hydrogen atoms are omitted for clarity. Selected
bond lengths [Å]: Cr1–Cl1 2.3682(4), Cr1–C13 2.0192(14), C13–
C14 1.2171(19), C14–C15 1.378(2), C15–C16 1.214(2), C16–Si1
1.8383(16).
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H. Berke et al.
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obtained with a BAS 100W voltammetric analyzer. The cell was
equipped with a Au working and Pt counter electrode, and a non-
aqueous reference electrode. All sample solutions were approxi-
mately 5ϫ10–3 m in the substrate and 0.1 m in Bu4NPF6, and were
prepared under nitrogen. The BAS 100W program was employed
for data analysis. X-band EPR spectra were obtained using a
Bruker EMX electron spin resonance system. The starting material
Conclusions
We have reported dinuclear and mononuclear chromium
acetylide complexes. The dinuclear complexes with the buta-
diyne bridge show a class-I type electron-transfer behavior,
which is very untypical of dinuclear complexes bridged by
a C4 unit. Further substitution of the chlorido ligand for
the corresponding iodido group and the trimethylsilyl alk- Cr(dmpe)2Cl2 (1) was prepared as described in the literature.[38]
ynyl terminated complexes did not have a significant influ-
X-ray Diffraction Studies: Single-crystal X-ray diffraction data were
ence on the electronic properties of the C4 bridge and the
chromium metal center. Also synthetic access to the reactive
trimethylstannyl alkynyl mononuclear complexes was
achieved. These complexes can be utilized as new building
blocks for the synthesis and investigation of electron-trans-
fer properties of heterodinuclear and further on oligonu-
clear complexes with various metal centers, which is cur-
rently ongoing in our group.
collected at 183(2) K with an Xcalibur diffractometer (Agilent
Technologies, Ruby CCD detector) for compounds 2, 2[SnMe3-
Cl2]2, 8, and 10, and with a SuperNova Dual diffractometer (Ag-
ilent Technologies, Atlas CCD detector) for compound 9 using a
single wavelength Enhance X-ray source with Mo-Kα radiation (λ
= 0.71073 Å).[51] The selected suitable single crystals were mounted
using polybutene oil on the top of a glass fiber fixed onto a goni-
ometer head and immediately transferred to the diffractometer.
Pre-experiment, data collection, data reduction, and analytical ab-
sorption corrections[52] were performed with the program suite
CrysAlisPro [51]
The crystal structures were solved with the program
.
Experimental Section
SHELXS97[53] using direct methods. The structure refinements
were performed by full-matrix least-squares on F2 with
SHELXL97.[53] All programs used during the crystal structure de-
termination process are included in the WINGX software.[54] The
program PLATON[55] was used to check the result of the X-ray
analyses and DIAMOND[56] was used for the molecular graphics.
All the manipulations were carried out under a nitrogen atmo-
sphere using Schlenk techniques or a glovebox (M. Braun 150B-
G-II). The solvents benzene, toluene, pentane, diethyl ether, and
tetrahydrofuran were dried and distilled from sodium benzophe-
none prior to use. Dichloromethane and acetonitrile were distilled
from CaH2. CHN elemental analyses were performed with a LECO
CHN-932 microanalyzer. IR spectra were obtained with a Bio-Rad
FTS-45 instrument. NMR spectra were measured with a Varian
Mercury spectrometer at 200 MHz for the 1H NMR and Varian
Gemini-2000 spectrometer at 300 MHz for 1H NMR. The chemical
shift for the 1H NMR is given in ppm relative to TMS and for
31P NMR relative to phosphoric acid. Cyclic voltammograms were
CCDC-841965 (for 2), -841966 (for 2[SnMe3Cl2]2), -841967 (for
8), -841968 (for 9), and -841969 (for 10) contain the supplementary
crystallographic data (excluding structure factors) for this paper.
These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif.
Table 2. Crystallographic data for compounds 2 and 2[SnMe3Cl2]2.
2
2[SnMe3Cl2]2
Empirical formula
Mr [gmol–1]
T [K]
C28H64Cl2Cr2P8
823.45
183(2)
C28H64Cl2Cr2P8, 2(C3H9Cl2Sn), 2(CH2Cl2)
1462.73
183(2)
λ [Å]
0.71073
0.71073
Crystal system, Space group
a [Å]
b [Å]
c [Å]
α [°]
orthorhombic, C2221
12.4500(3)
13.6928(3)
25.2013(7)
90
monoclinic, C2/c
31.1484(12)
10.7228(2)
22.6263(9)
90
β [°]
90
90
117.419(5)
90
6708.2(5)
4, 1.448
γ [°]
V [Å3]
4296.20(18)
4, 1.273
0.946
Z, ρcalcd [Mgm–3]
μ [mm–1]
1.664
F(000)
Crystal size [mm]
θ range [°]
Measured reflections
Unique reflections
Completeness to θ [%]
Absorption correction
Max./min. transmission
Data/restraints/parameters
Gof on F2
1736
2960
0.35ϫ0.29ϫ0.025
2.21–28.28
14101
5334 [Rint = 0.058]
99.8
analytical
0.980 and 0.800
3768/7/209
0.900
0.24ϫ0.13ϫ0.04
2.62–25.68
18095
6349 [Rint = 0.058]
99.9
analytical
0.959 and 0.823
3818/0/273
0.859
Final R1 and wR2 indices [IϾ2σ(I)]
R1 and wR2 indices (all data)
Absolute structure parameter
Largest diff. peak and hole (eÅ–3)
0.0431, 0.0688
0.0726, 0.0739
0.10(2)
0.0401, 0.0688
0.0858, 0.0752
0.647 and –0.440
0.673 and –0.639
The unweighted R factor is R1 = Σ(Fo – Fc)/ΣFo; IϾ2σ(I) and the weighted R factor is wR2 = {Σ[w(Fo – Fc ) ]/Σ[w(Fo2)2]}1/2
.
2
2 2
1542
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 1536–1545

Dinuclear and Mononuclear Chromium Acetylide Complexes
Table 3. Crystallographic data for compounds 8, 9, and 10.
8
9
10
Empirical formula
Mr [gmol–1]
T [K]
C19H41ClCrP4Si
508.94
183(2)
C19H41ClCrP4Sn
599.56
183(2)
C25H45ClCrP4Sn
675.65
183(2)
λ [Å]
0.71073
0.71073
0.71073
Crystal system, space group
a [Å]
b [Å]
c [Å]
α [°]
monoclinic, P21/c
9.2024(6)
11.7569(5)
26.235(5)
90
monoclinic, P21/c
9.1399(13)
11.7256(4)
26.5608(10)
90
orthorhombic, Iba2
19.6605(4)
28.1754(5)
11.9620(2)
90
β [°]
92.944(10)
90
2834.7(6)
4, 1.193
92.761(6)
90
2843.2(4)
4, 1.401
90
90
6626.3(2)
8, 1.355
1.367
γ [°]
V [Å3]
Z, ρcalcd. [Mgm–3]
μ [mm–1]
0.769
1.583
F(000)
Crystal size [mm]
θ range [°]
Measured reflections
Unique reflections
Completeness to θ [%]
Absorption correction
Max./min. transmission
Data/restraints/parameters
Gof on F2
1080
1224
2768
0.33ϫ0.28ϫ0.15
2.64–30.51
51206
8642 [Rint = 0.028]
100.0
analytical
0.908 and 0.819
7749/0/246
1.088
0.31ϫ0.09ϫ0.08
2.23–28.28
15141
7725
94.4
analytical
0.971 and 0.923
7080/0/247
1.081
0.37ϫ0.20ϫ0.08
2.78–30.51
20775
9810 [Rint = 0.060]
99.9
analytical
0.954 and 0.828
6604/46/319
0.920
Final R1 and wR2 indices [IϾ2σ(I)]
R1 and wR2 indices (all data)
Absolute structure parameter
Largest diff. peak and hole (eÅ–3)
0.0300, 0.0717
0.0355, 0.0743
0.0611, 0.1752
0.0658, 0.1791
0.0505, 0.1102
0.0752, 0.1159
0.06(2)
0.604 and –0.390
3.971 and –0.914
1.007 and –1.053
2
2 2
The unweighted R factor is R1 = Σ(Fo – Fc)/ΣFo; IϾ2σ(I) and the weighted R factor is wR2 = {Σ[w(Fo – Fc ) ]/Σ[w(Fo2)2]}1/2
In the crystal structure of 2 the asymmetric unit consists of one
half of the molecule. The second part of the molecule is generated
by a symmetry from a twofold axis. The ethane group (C9–C10) of
one dmpe ligand is disordered over two sets of positions with site-
occupancy factors of 0.459(19) and 0.541(19). Some restraints were
used to correct the geometry of the disordered group. In the crystal
structure of 2[SnMe3Cl2]2, the asymmetric unit consists of one half
of the dicationic chromium species, one anionic dichlorotrimeth-
yltin molecule, and one solvent molecule of dichloromethane. The
dinuclear species lies on a twofold axis, one part is refined and the
second part is reproduced by a symmetry operation. The crystal
data for compounds 2 and 2[SnMe3Cl2]2 are given in Table 2. The
structure of compound 9 has been refined as a nonmerohedral twin
with the CrysAlisPro twin data module.[51] The nonmerohedral twin
matrix has been identified and a single HKLF-5 file containing
reflections from both domains was employed for the final structure
refinement. Refinement using a single lattice and no twin treatment
afforded R1 = 19.5%, with residual peaks as large as 6.85 eÅ–3.
Full treatment as a twin with application of an analytical absorp-
tion correction resulted in R1 = 6.1% with the strongest residual
peak of 3.97 eÅ–3. In the crystal structure of 10, the ethane group
(C20–C21) of one dmpe ligand is disordered over two sets of posi-
tions with site-occupancy factors of 0.452(17) and 0.548(17). Some
restraints were used to correct the geometry of the disordered
group and the thermal parameters of the corresponding carbon
atoms. The crystal data for compounds 8, 9, and 10 are given in
Table 3. For all five refinements, all hydrogen positions were calcu-
lated after each cycle of refinement using a riding model, with C–
H = 0.97 Å and Uiso(H) = 1.2Ueq(C) for methylene H atoms, and
with C–H = 0.96 Å and Uiso(H) = 1.5Ueq(C) for methyl H atoms.
0.142 mmol) was added to a solution of Cr(dmpe)2Cl2 (120 mg,
0.284 mmol) in benzene (35 mL) in the presence of metallic Zn.
The reaction mixture was heated to 80 °C and the mixture was
stirred overnight. The solvent was removed in vacuo and the solid
residue was washed with pentane and subsequently extracted with
benzene. Recrystallization from THF/pentane at –30 °C gave red
crystals; yield 64.2 mg (55%). 1H NMR (200 MHz, [D8]THF,
25 °C): δ = 1.28 (s, 12 H, PCH3), 1.31 (s, 12 H, PCH3), 1.55 (m, 8
H, CH2), 1.67 (m, 8 H, PCH2) ppm. 31P{1H} NMR (81 MHz,
[D ]THF, 25 °C): δ = 64.54 (s) ppm. IR (ATR): ν = 2950 (C–H),
˜
8
2050 (CϵC), 922 (C–P) cm–1. ESI–MS (C28H64Cl2Cr2P8): m/z =
822 [M]+. C28H64Cl2Cr2P8 (822.27): calcd. C 40.83, H 7.78; found
C 40.69, H 7.74.
trans-[Cl(dmpe)2Cr–CϵC–CϵC–Cr(dmpe)2Cl][SnMe3Cl2]2 (2[Sn-
Me3Cl2]2): A benzene solution (15 mL) of Me3SnCϵC–CϵC–
SnMe3 (44.3 mg, 0.118 mmol) was added to a solution of Cr-
(dmpe)2Cl2 (100 mg, 0.237 mmol) in benzene (30 mL). The tem-
perature was raised to 80 °C and the mixture was stirred overnight.
The solvent was removed and the red solid was washed with THF
and extracted with dichloromethane. Recrystallization with
CH2Cl2/pentane at –30 °C gave red crystals; yield 68.9 mg (45%).
1H NMR (200 MHz, CD2Cl2, 25 °C): δ = –19.63 (br., 8 H, PCH2,
24 H, PCH ) ppm. IR (ATR): ν = 2986 (C–H), 1917 (C=C), 953
˜
3
(C–P) cm–1. ESI–MS (C34H82Cl2Cr2P8Sn2): m/z = 411 [M]2+
.
C34H82Cl2Cr2P8Sn2 (1151.09): calcd. C 31.59, H 6.35; found C
31.70, H 6.41.
trans-[Cl(dmpe)2Cr–CϵC–CϵC–Cr(dmpe)2Cl][PF6]2 (2[PF6]2):
A
CH2Cl2 suspension of NaPF6 (25.87 mg, 0.154 mmol) was added
to a CH2Cl2 solution of (2[SnMe3Cl2]2) (100 mg, 0.077 mmol). This
mixture was stirred for 1 h at room temperature. The solvent was
evaporated and the product was extracted with THF. The THF
solution was evaporated in vacuo to give the title compound.
trans-[Cl(dmpe)2CrϵC–CϵC–CϵCr(dmpe)2Cl] (2):
A
benzene
[57]
solution (20 mL) of Me3Sn–CϵC–CϵC–SnMe3
(53.34 mg,
Eur. J. Inorg. Chem. 2012, 1536–1545
© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
1543

H. Berke et al.
FULL PAPER
Crystallization from a mixture of dichloromethane and ether at
–35 °C produced single red crystals; yield 87 mg, 0.08 mmol (78%).
then the solvent was removed in vacuo; yield 58.0 mg (82%). 1H
NMR (200 MHz, [D8]toluene, 25 °C): δ = –13.9 (br., 8 H, PCH2),
1H NMR (300 MHz, CD2Cl2, 22 °C): δ = –17.92 (br., 8 H, PCH2, –29.1 (br., 12 H, PCH3), –33.7 (br., 12 H, PCH3) ppm. IR (ATR):
24 H, PCH3) ppm. 31P{1H} NMR (121.5 MHz, CD2Cl2, 22 °C): δ
ν =
2900 (C–H), 1950 (CϵC), 920 (C–P) cm–1. ESI–MS
˜
1
–
= –146.1 (sept, JPF = 714 Hz, PF6 ) ppm. 19F {1H} NMR
(C17H41ClCrP4Sn): m/z = 576.1 [M]+. C17H41ClCrP4Sn (576.1):
1
(282.3 MHz, CD2Cl2, 22 °C): δ = –74.8 (d, JFP = 714 Hz,
calcd. C 35.47, H 7.13; found C 35.25, H 7.12.
–
PF ) ppm. IR (ATR): ν = 2927 (w), 2888 (w) (C–H), 2083 (m)
˜
6
trans-[Cl(dmpe)2Cr–CϵC–Ph] (7): A benzene solution (20 mL) of
Cr(dmpe)2Cl2 (40 mg, 0.095 mmol) and a benzene solution (15 mL)
of Me3Sn–CϵC–Ph (26.3 mg, 0.099 mmol) were mixed and stirred
for 12 h at 80 °C. After evaporation of the solvent, the product was
washed with cool pentane, extracted with pentane, and dried in
vacuo; yield 43 mg (93%). 1H NMR (200 MHz, [D8]toluene,
25 °C): δ = 33.2, (br., 4 H, Ph), –51.3 (br., 4 H, Ph), –6.9 (br., 8 H,
PCH2), –9.3 (br., 8 H, PCH2), –29.4 (br., 12 H, PCH3), –32.5 (br.,
(CϵC), 980 (s), 941 (s) (P–C), 865 (vs) (P–F) cm–1.
C28H64Cl2Cr2F12P10 (1113.42): calcd. C 30.20, H 5.79; found C
29.98, H 5.60.
trans-[Cl(dmpe)2Cr–CϵC–Ph–CϵC–Cr(dmpe)2Cl][SnMe3Cl2]2
(3[SnMe3Cl2]2): Cr(dmpe)2Cl2 (90 mg, 0.213 mmol) and Me3Sn–
CϵC–Ph–CϵC–SnMe3 (48.1 mg, 0.107 mmol) were dissolved in
benzene (40 mL). The mixture was stirred for 12 h at 80 °C. After
evaporation of the solvent the product was washed with THF and
extracted with CH3CN and then the solvent was removed in vacuo;
yield 58.3 mg (40%). 1H NMR (200 MHz, [D8]THF, 25 °C): δ =
–14.5 (br., 8 H, PCH2), –35.9 (br., 12 H, PCH3), –37.8 (br., 12 H,
12 H, PCH ) ppm. IR (ATR): ν = 2965 (C–H), 2032 (CϵC), 1587
˜
3
(C=C), 984 (C–P) cm–1. ESI–MS (C20H37ClCrP4): m/z = 488.2
[M]+. C20H37ClCrP4 (488.5): calcd. C 49.13, H 7.6; found C 49.26,
H 7.48.
PCH3) ppm. ESI–MS (C40H86B2Cl6Cr2P8Sn2): m/z = 449.2 [M]2+
.
trans-[Cl(dmpe)2Cr–CϵC–CϵC–C–SiMe3] (8): Me3Sn–CϵC–
CϵC–C–SiMe3 (40.8 mg, 0.143 mmol) in benzene (20 mL) was
added to a benzene solution (20 mL) of Cr(dmpe)2Cl2 (55 mg,
0.130 mmol). The mixture was stirred overnight at 80 °C. After
evaporation of the solvent the product was extracted with pentane
and dried in vacuo. Recrystallization from pentane at –30 °C gave
red crystals; yield 49.7 mg (75%). 1H NMR (200 MHz, [D6]toluene,
25 °C): δ = –5.6 (br., 8 H, PCH2), –10.6 (br., 8 H, PCH2), –13.1
(br., 8 H, PCH2), –28.5 (br., 12 H, PCH3), –31.2 (br., 12 H, PCH3),
C40H86B2Cl6Cr2P8Sn2 (1369.0): calcd. C 35.09, H 7.33; found C
29.8, H 4.86.
trans-[Cl(dmpe)2Cr–CϵC–Ph–CϵC–Cr(dmpe)2Cl][BPh4]2 (3[BPh4]2):
A CH3CN solution of (3[SnMe3Cl2]2) (100 mg, 0.073 mmol) was
added to a CH3CN suspension of NaBPh4 (25.0 mg, 0.073 mmol).
This mixture was stirred for 1 h at room temperature. The solvent
was evaporated and the product was extracted with THF. The sol-
vent was evaporated in vacuo to give the title compound; yield
84.1 mg (75%). NMR (200 MHz, CD3CN, 25 °C): δ = –17.3 (br.,
8 H, PCH2), –24.2 (br., 8 H, PCH2), –45.7 (br., 12 H, PCH3), –55.5
–33.3 (br., 12 H, PCH ) ppm. IR (ATR): ν = 2964 (C–H), 2093
˜
3
(CϵC), 988 (C–P) cm–1. ESI–MS (C19H41ClCrP4Si): m/z = 508.1
[M]+. C19H41ClCrP4Si (508.0): calcd. C 44.84, H 8.12; found C
44.98, H 8.21.
(br., 12 H, PCH ) ppm. IR (ATR): ν = 2909 (C–H), 2196 (CϵC),
˜
3
1580 (C=C), 949 (C–P) cm–1. ESI–MS (C82H108B2Cl2Cr2P8): m/z =
449.2 [M]2+. C82H108B2Cl2Cr2P8 (1536.5): calcd. C 64.03, H 7.08;
found C 63.91, H 7.01.
trans-[Cl(dmpe)2Cr–CϵC–CϵC–SnMe3] (9): Cr(dmpe)2Cl2 (50 mg,
0.142 mmol)
and
Me3Sn–CϵC–CϵC–SnMe3
(58.7 mg,
0.156 mmol) were dissolved in benzene (50 mL), the mixture was
stirred overnight at 80 °C. The solvent was then evaporated and
the red solid was extracted with pentane, and then the solvent was
removed in vacuo. Recrystallization from pentane gave red crystals;
yield 42.6 mg (50%). H NMR (200 MHz, C6D6, 25 °C): δ = –6.2
(br., 8 H, PCH2), –10.5 (br., 8 H, PCH2), –13.3 (br., 8 H, PCH2),
–29.1 (br., 12 H, PCH3), –31.7 (br., 12 H, PCH3), –33.9 (br., 12 H,
trans-[I(dmpe)2CrϵC–CϵC–CϵCr(dmpe)2I] (4): KI (323.3 mg,
1.947 mmol) in THF (20 mL) was added to complex 2 (80 mg,
0.097 mmol) in THF (30 mL). The temperature was raised to 60 °C
and the solution was stirred overnight. After removal of the solvent
in vacuo the product was extracted with pentane and the solvent
was removed in vacuo; yield 68.44 mg (70%). 1H NMR (200 MHz,
C6D6, 25 °C): δ = 1.28 (s, 12 H, PCH3), 1.64 (s, 12 H, PCH3), 1.35
(m, 8 H, CH2), 1.71 (m, 8 H PCH2) ppm. 31P{1H} NMR (81 MHz,
1
PCH ) ppm. IR (ATR): ν = 2964 (C–H), 2100 (CϵC), 936 (C–
˜
3
P) cm–1. ESI–MS (C19H41ClCrP4Sn): m/z
=
600.0 [M]+.
[D ]THF, 25 °C): δ = 49.8 (s) ppm. IR (ATR): ν = 2961 (C–H),
˜
8
2150 (CϵC), 921 (C–P) cm–1. ESI–MS (C28H64I2Cr2P8): m/z =
1006.0 [M]+. C28H64Cr2I2P8 (1005.98): calcd. C 33.42, H 6.41;
found C 33.29, H 6.30.
C19H41ClCrP4Sn (600.0): calcd. C 38.06, H 6.89; found C 37.78,
H, 6.55.
trans-[Cl(dmpe)2Cr–CϵC–Ph–CϵC–SnMe3] (10): Cr(dmpe)2Cl2
(60 mg, 0.118 mmol) and Me3Sn–CϵC–Ph–CϵC–SnMe3 (70.4 mg,
0.156 mmol) were dissolved in benzene (25 mL). The mixture was
stirred for 12 h at 80 °C. After evaporation of the solvent the prod-
uct was extracted in pentane and dried in vacuo. Recrystallization
from pentane gave red crystals; yield 46.1 mg (48%). 1H NMR
(200 MHz, [D8]toluene, 25 °C): δ = 37.6 (br., 4 H, Ph), –53.8 (br.,
4 H, Ph), –9.4 (br., 8 H, PCH2), –29.8 (br., 12 H, PCH3), –32.6
trans-[Me3Si–CϵC(dmpe)2CrϵC–CϵC–CϵCr(dmpe)2Cϵ
C–SiMe3] (5): Complex 2 (100 mg, 0.122 mmol) in THF (30 mL)
and a freshly prepared solution of Li–CϵC–SiMe3 (88.6 mg,
0.852 mmol) in THF (20 mL) were mixed and stirred at 60 °C over-
night. The solvent was then evaporated and the red-brown solid
was extracted with pentane and the solvent was removed in vacuo;
yield 77 mg. (67%). 1H NMR (200 MHz, C6D6, 25 °C): δ = 0.18
[s, 18 H, Si(CH3)3], 1.31 (m, 12 H, PCH3), 1.42 (m, 12 H, PCH3),
(br., 12 H, PCH ) ppm. IR (ATR): ν = 2900 (C–H), 2018 (CϵC),
˜
3
1592 (C=C), 984 (C–P) cm–1. ESI–MS(C25H45ClCrP4Sn): m/z =
676.7 [M]+. C25H45ClCrP4Sn (676.3): calcd. C 49.13, H 7.6; found
C 49.26, H 7.48.
1.55 (m, 8 H, CH ), 1.69 (m, 8 H, PCH ) ppm. IR (ATR): ν = 2959
˜
2
2
(C–H), 2190 (CϵC), 934 (C–P) cm–1. ESI–MS (C38H82Si2Cr2P8):
m/z = 946.3 [M]+. C38H82Cr2P8Si2 (946.3): calcd. C 48.19, H 8.73;
found C 47.98, H 8.66.
trans-[Cl(dmpe)2Cr–CϵC–SnMe3] (6): Cr(dmpe)2Cl2 (50 mg,
0.118 mmol) and Me3Sn–CϵC–SnMe3 (43.8 mg, 0.124 mmol) were
dissolved in benzene (40 mL). The mixture was stirred for 12 h at
80 °C. After evaporation of the solvent the product was washed
with a small amount of cold pentane, extracted in pentane, and
Acknowledgments
Funding from the University of Zürich is gratefully acknowledged.
We thank Dr. Sergey N. Semenov for SQUID and EPR measure-
ments.
1544
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© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2012, 1536–1545

Dinuclear and Mononuclear Chromium Acetylide Complexes
[28] V. W. W. Yam, K. M. C. Wong, N. Y. Zhu, Angew. Chem. 2003,
115, 1438; Angew. Chem. Int. Ed. 2003, 42, 1400.
[29] B. E. Woodworth, P. S. White, J. L. Templeton, J. Am. Chem.
Soc. 1997, 119, 828.
[30] R. L. Roberts, H. Puschmann, J. A. K. Howard, J. H. Yamam-
oto, A. J. Carty, P. J. Low, Dalton Trans. 2003, 1099.
[31] K. Venkatesan, T. Fox, H. W. Schmalle, H. Berke, Organome-
tallics 2005, 24, 2834.
[32] K. Venkatesan, O. Blacque, T. Fox, M. Alfonso, H. W.
Schmalle, S. Kheradmandan, H. Berke, Organometallics 2005,
24, 920.
[33] S. Kheradmandan, K. Heinze, H. W. Schmalle, H. Berke, An-
gew. Chem. 1999, 111, 2412; Angew. Chem. Int. Ed. 1999, 38,
2270.
[1]
J. Del Nero, F. M. de Souza, R. B. Capaz, J. Comput. Theor.
Nanosci. 2010, 7, 503.
J. R. Heath, Ann. Rev. Mater. Res. 2009, 39, 1.
R. L. Carroll, C. B. Gorman, Angew. Chem. 2002, 114, 4556;
Angew. Chem. Int. Ed. 2002, 41, 4378.
Z. Y. Li, D. S. Kosov, J. Phys. Chem. B 2006, 110, 19116.
L. M. Yan, E. J. Bautista, J. M. Seminario, Nanotechnology
2007, 18, 8.
S. A. Getty, C. Engtrakul, L. Wang, R. Liu, S. H. Ke, H. U.
Baranger, W. Yang, M. S. Fuhrer, L. R. Sita, Phys. Rev. B 2005,
71, 241401.
T. L. Schull, J. G. Kushmerick, C. H. Patterson, C. George,
M. H. Moore, S. K. Pollack, R. Shashidhar, J. Am. Chem. Soc.
2003, 125, 3202.
F. Paul, C. Lapinte, Coord. Chem. Rev. 1998, 178, 431.
G. Frapper, M. Kertesz, Inorg. Chem. 1993, 32, 732.
P. Aguirre-Etcheverry, D. O’Hare, Chem. Rev. 2010, 110, 4839.
M. D. Ward, Chem. Soc. Rev. 1995, 24, 121.
[2]
[3]
[4]
[5]
[6]
[7]
[34] M. I. Bruce, K. Costuas, T. Davin, J. F. Halet, K. A. Kramar-
czuk, P. J. Low, B. K. Nicholson, G. J. Perkins, R. L. Roberts,
B. W. Skelton, M. E. Smith, A. H. White, Dalton Trans. 2007,
5387.
[8]
[9]
[10]
[11]
[12]
[35] S. N. Semenov, O. Blacque, T. Fox, K. Venkatesan, H. Berke,
J. Am. Chem. Soc. 2010, 132, 3115.
[36] M. B. Robin, A. P. Day, Adv. Inorg. Chem. Radiochem. 1967,
10, 247.
M. Brady, W. Q. Weng, Y. L. Zhou, J. W. Seyler, A. J. Amoroso,
A. M. Arif, M. Böhme, G. Frenking, J. A. Gladysz, J. Am.
Chem. Soc. 1997, 119, 775.
D. Astruc, J. Ruiz, M. Lacoste, B. Gloaguen, N. Ardoin, J.
Linares, F. Varret, J. Chem. Soc., Chem. Commun. 1995, 1565.
[37] S. G. Girolami, J. E. Salt, G. Wilkinson, M. Thornton-Pett,
M. B. Hursthouse, J. Am. Chem. Soc. 1983, 105.
[38] A. Lopez-Hernandez, K. Venkatesan, H. W. Schmalle, H.
Berke, Monatsh. Chem. 2009, 140, 845.
[39] L. A. Berben, S. A. Kozimor, Inorg. Chem. 2008, 47, 4639.
[40] M. B. Robin, P. Day, Adv. Inorg. Chem. Radiochem. 1973, 95,
1086.
[13]
[14] C. G. Atwood, W. E. Geiger, J. Am. Chem. Soc. 2000, 122,
5477.
[15] R. Maul, W. Wenzel, Phys. Rev. B 2009, 80, 045424.
[16] S. Santi, L. Orian, A. Donoli, C. Durante, A. Bisello, M.
Di Valentin, P. Ganis, F. Benetollo, A. Ceccon, J. Organomet.
Chem. 2008, 693, 3797.
[17] R. D. Adams, B. Qu, Organometallics 2000, 19, 2411.
[18] S. Creager, C. J. Yu, C. Bamdad, S. O’Connor, T. MacLean, E.
Lam, Y. Chong, G. T. Olsen, J. Y. Luo, M. Gozin, J. F.
Kayyem, J. Am. Chem. Soc. 1999, 121, 1059.
[19] R. Dembinski, T. Bartik, B. Bartik, M. Jaeger, J. A. Gladysz,
J. Am. Chem. Soc. 2000, 122, 810.
[41] R. D. Markwell, I. S. Butler, A. K. Kakkar, M. S. Khan, Z. H.
Al Zakwani, J. Lewis, Organometallics 1996, 15, 2331.
[42] I. Vidal, S. Melchor, J. A. Dobado, J. Phys. Chem. A 2005, 109,
7500.
[43] R. R. Schrock, Chem. Rev. 2002, 102, 145.
[44] J. T. Lyon, H. G. Cho, L. Andrews, Organometallics 2007, 26,
6373.
[45] N. Re, A. Sgamellotti, C. Floriani, Organometallics 2000, 19,
1115.
[46] S. B. Braun-Sand, O. Wiest, J. Phys. Chem. B 2003, 107, 9624.
[47] B. S. Brunschwig, C. Creutz, N. Sutin, Chem. Soc. Rev. 2002,
31, 168.
[20] U. H. F. Bunz, Angew. Chem. 1996, 108, 1047; Angew. Chem.
Int. Ed. Engl. 1996, 35, 969.
[21] J. M. Manriquez, M. D. Ward, W. M. Reiff, J. C. Calabrese,
N. L. Jones, P. J. Carroll, E. E. Bunel, J. S. Miller, J. Am. Chem.
Soc. 1995, 117, 6182.
[48] P. T. Kissinger, W. R. Heineman, J. Chem. Educ. 1983, 60, 702.
[49] S. N. Semenov, S. F. Taghipourian, O. Blacque, T. Fox, K. Ven-
katesan, H. Berke, J. Am. Chem. Soc. 2010, 132, 7584.
[50] M. L. Huggins, J. Am. Chem. Soc. 1953, 75, 4124.
[51] Agilent Technologies (formerly Oxford Diffraction), Yarnton,
England, 2011.
[52] R. C. Clark, J. S. Reid, Acta Crystallogr. 1995, A51, 887–897.
[53] G. M. Sheldrick, Acta Crystallogr. 2008, A64, 112–122.
[54] L. J. Farrugia, J. Appl. Crystallogr. 1999, 32, 837.
[55] A. L. Spek, J. Appl. Crystallogr. 2003, 36, 7–13.
[56] K. Brandenburg, DIAMOND, Crystal Impact GbR, Bonn,
Germany, 2006..
[22] N. Lenarvor, L. Toupet, C. Lapinte, J. Am. Chem. Soc. 1995,
117, 7129.
[23] H. J. Jiao, K. Costuas, J. A. Gladysz, J. F. Halet, M. Guillemot,
L. Toupet, F. Paul, C. Lapinte, J. Am. Chem. Soc. 2003, 125,
9511.
[24] Y. L. Zhou, J. W. Seyler, W. Q. Weng, A. M. Arif, J. A. Gladysz,
J. Am. Chem. Soc. 1993, 115, 8509.
[25] V. W. W. Yam, V. C. Y. Lau, K. K. Cheung, Organometallics
1996, 15, 1740.
[26] F. Paul, W. E. Meyer, L. Toupet, H. J. Jiao, J. A. Gladysz, C. [57] L. Brandsma, Preparative Acetylenic Chemistry, 2nd ed., Elsev-
Lapinte, J. Am. Chem. Soc. 2000, 122, 9405.
[27] M. I. Bruce, P. J. Low, K. Costuas, J. F. Halet, S. P. Best, G. A.
Heath, J. Am. Chem. Soc. 2000, 122, 1949.
ier, Amsterdam, 1998.
Received: September 2, 2011
Published Online: December 2, 2011
Eur. J. Inorg. Chem. 2012, 1536–1545
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