New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl Complexes Based on Cobalt(III)(cyclam)(C2NAPMes)

Article abstract of DOI:10.1002/ejic.201901070

The synthesis and characterization of dissymmetric Co^III-bis-alkynyl complexes supported by cyclam (1,4,8,11-tetraazacyclotetradecane) are reported. A series of trans-[Co(cyclam)(C₂NAP^R)Cl]Cl were prepared from the reaction between [Co(cyclam)Cl₂]Cl and HC₂NAP^R in the presence of Et₃N, where NAP^R is N-R-1,8-naphthalimide with R as mesityl (Mes, 1a), methyl (Me, 1b), 1-ethylpropyl (Pen, 1c), 2-ethylhexyl (2-ethhex, 1d), or n-octyl (Oct, 1e). Treating compounds 1a and 1b with AgOTf in NCCH₃ resulted in trans-[Co(cyclam)(C₂NAP^R)(NCCH₃)](OTf)₂ (2a and 2b, respectively), while reactions with 1c, 1d and 1e under the same conditions yielded only intractable mixtures. More soluble 2a reacted further with HC₂Ar in the presence of Et₃N to afford trans-[Co(cyclam)(C₂NAP^R)(C₂Ar)](OTf) with Ar as C₆H₄-4-NMe₂ (3a), NAP^Mes (3b) and Ph (3c). All new complexes were characterized using X-ray diffraction (1a, 1c and 3b), IR, ¹H NMR, UV/Vis and fluorescent spectroscopy, and cyclic voltammetry.

Full text of DOI:10.1002/ejic.201901070

DOI: 10.1002/ejic.201901070
Full Paper
Dissymmetric Cobalt Complexes
New Synthetic Route for Cobalt(III) Dissymmetric Bisalkynyl
Complexes Based on Cobalt(III)(cyclam)(C2NAPMes)
Susannah D. Banziger,[a] Matthias Zeller,[a] and Tong Ren*[a]
Abstract: The synthesis and characterization of dissymmetric NCCH3 resulted in trans-[Co(cyclam)(C2NAPR)(NCCH3)](OTf)2 (2a
CoIII-bis-alkynyl complexes supported by cyclam (1,4,8,11-tetra- and 2b, respectively), while reactions with 1c, 1d and 1e under
azacyclotetradecane) are reported. A series of trans-[Co(cyclam)- the same conditions yielded only intractable mixtures. More solu-
(C2NAPR)Cl]Cl were prepared from the reaction between [Co- ble 2a reacted further with HC2Ar in the presence of Et3N to
(cyclam)Cl2]Cl and HC2NAPR in the presence of Et3N, where NAPR afford trans-[Co(cyclam)(C2NAPR)(C2Ar)](OTf) with Ar as C6H4-4-
is N-R-1,8-naphthalimide with R as mesityl (Mes, 1a), methyl (Me, NMe2 (3a), NAPMes (3b) and Ph (3c). All new complexes were
1
1b), 1-ethylpropyl (Pen, 1c), 2-ethylhexyl (2-ethhex, 1d), or n- characterized using X-ray diffraction (1a, 1c and 3b), IR, H NMR,
octyl (Oct, 1e). Treating compounds 1a and 1b with AgOTf in UV/Vis and fluorescent spectroscopy, and cyclic voltammetry.
Introduction
alkynyls has been measured in nanojunctions,[15] and functional
The understanding of electron transfer processes is paramount
devices with metal alkynyls as the active species have been
to chemistry, biology and material sciences.[1,2] Photoinduced
fabricated.[16]
electron transfer (PET) has been very topical because of its rele-
While the majority of the abovementioned examples are
vance to both natural photosynthesis[1] and photovoltaics.[3] Re-
based on 4d and 5d metals, our laboratory has been exploring
cent years have seen efforts towards attenuation of intramolec-
alkynyl chemistry based on M(cyclam) unit with M as 3d metals
ular photo-induced electron transfer either through external
such as Cr, Fe, Co and Ni.[17,18] Aiming at achieving PET attenua-
stimuli such as pH change,[4] hydrogen bonding[5] or structural
tion in related 3d metal complexes, D-B-A compounds based on
modification of the bridge between the donor and the ac-
CoIII(cyclam) have been selectively prepared in high yields[17,18]
ceptor.[6] An interesting alternative approach is to modulate the
through two different routes: i) stepwise alkynylation, with the
evolution of electronic excited states through the excitation of
first step proceeding under weak base conditions and the sec-
a specific bond along the PET pathway. Working with a series
ond utilizing lithiated acetylide[19,20] and ii) stepwise alkynyl-
of donor-bridge-acceptor (D-B-A) compounds with a trans-PtII-
ation under weak base conditions via a triflate intermedi-
bis-alkynyl bridge, Weinstein and co-workers demonstrated that
ate[21,22] as shown in Scheme 1. Each synthetic route suffers
the decay pathways of the PET excited state may be signifi-
from harsh conditions, with the most notable being (i) use of a
cantly attenuated by the IR excitation of the Pt-bound C≡ C
strong base and (ii) high temperature. Previous work to synthe-
bonds.[7,8]
size the first dissymmetric D-B-A CoIII(cyclam) complexes, where
In addition to illustrating the control of PET processes using
D = C6H4-4-NR′2 (R′ = Me or Ph-4-OMe) and A = N-isopropyl-
vibrational pumping, work of Weinstein also demonstrates the
advantage of conjugated metal alkynyls as electronic and opto-
electronic materials.[9,10] Importantly, the rigidity of metal alkyn-
yls allows for unambiguous establishment of structure-property
relationships.[11,12] Hence, bimetallic species bridged by oligo-
yn-diyl have become a favorite target as prototypical molecular
wires,[13] for which the precise distance dependence of metal-
metal electronic couplings can be established using mixed va-
lence theory.[14] Though rare, molecular conductance of metal
[a] Dr. S. D. Banziger, Dr. M. Zeller, Prof. Dr. T. Ren
Department of Chemistry, Purdue University,
560 Oval Drive, West Lafayette, IN 47906, USA
E-mail: tren@purdue.edu
http://www.chem.purdue.edu/tren/
Supporting information and ORCID(s) from the author(s) for this article are
available on the WWW under https://doi.org/10.1002/ejic.201901070.
Scheme 1. Syntheses of dissymmetric D-B-A compounds based on CoIII(cyc-
lam). Route i.) use of a strong base at low temp. Route ii.) use of a triflate
intermediate in the presence of weak base and heat.
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1,8-naphthalimide (NAPiPr), could only be accomplished using
Synthesis of mono acetylide CoIII(cyclam) compounds 1a–1e
the first route.[18] Since that time, our group has investigated was accomplished under N2 through the reaction of HC2NAPR
the tuning of reactivity, crystallinity, and “robustness” of the
naphthalimide unit through altering the alkyl group directly
linked to the imide. Reported herein is the synthesis of new
CoIII(cyclam)(C2NAPR) species with R as mesityl (Mes, 1a), methyl
(Me, 1b), 1-ethylpropyl (Pen, 1c), 2-ethylhexyl (2-ethhex, 1d), or
n-octyl (Oct, 1e) and a discussion on their properties and reac-
tivity (Scheme 2). It should be noted that we have benefited
from the early development of naphthalimide-acetylene chem-
istry by McAdam and co-workers, including Ni, Fe and Ru com-
pounds of C2NAPMe[23] and naphthalimide-acetylene ferrocenyl
conjugates.[24,25]
(R is defined in Scheme 2) with [Co(cyclam)Cl2]Cl in the pres-
ence of Et3N.[18] Except for 1b, purification over silica resulted
in bright orange microcrystalline solids in 45–63 % yield. Due
to low solubility of 1b, its isolation was accomplished by addi-
tion of ether to the crude reaction mixture to yield a light or-
ange powder in 48 % yield. Reaction of AgOTf (5 equiv.) with
1a and 1b in NCCH3 resulted in [Co(cyclam)(C2NAPMes)-
(NCCH3)](OTf)2 (2a) and [Co(cyclam)(C2NAPMe)(NCCH3)](OTf)2
(2b), respectively, as yellow powders. Attempts to synthesize
[Co(cyclam)(C2NAPR)(NCCH3)](OTf)2 type intermediates based
on 1c–1e led to the consumption of the starting materials, but
intractable products. Plausible causes of degradation include
hydrolytic cleavage of the imido groups in NAPR and Co–C
bond cleavage aided by Ag(I) coordination to the C≡ C bond.
Hence, dissymmetric complexes based on NAPPen, NAP2–ethhex
,
and NAPOct were not pursued further. The reaction between 2b
and HC2C6H4-4-NMe2 in the presence of Et3N afforded [Co-
(cyclam)(C2NAPMe)(C2C6H4-4-NMe2)]OTf as a light orange pow-
der in 29 % yield. However, poor solubility of [Co(cyclam)-
(C2NAPMe)(C2C6H4-4-NMe2)]OTf made further characterization
difficult. Hence, efforts to synthesize dissymmetric bis-alkynyls
focused on the significantly more soluble NAPMes derivatives.
Scheme 2. [Co(cyclam)(C2NAPR)Cl]Cl type compounds.
[Co(cyclam)(C2NAPMes)(C2C6H4-4-NMe2)]OTf (3a), [Co(cyclam)-
(C2NAPMes)2]OTf (3b), and [Co(cyclam)(C2NAPMes)(C2Ph)]OTf (3c)
were synthesized from 2a under N2 in the presence of excess
HC2Ar and Et3N as shown in Scheme 4. Compounds 3b and 3c
were isolated as bright yellow solids and 3a as a light orange
solid. Low reaction yields for 3a (39 %) and 3b (11 %) were attrib-
uted to the hydroamination of –C≡ C–NAPMes by Et3N to form
[Et3NC2H2NAPMes]OTf, which was isolated and characterized (ESI).
Hydroamination of alkynes in the presence of perchlorate salts
to form vinyl tertiary amines was initially reported by Fischer in
1968.[27] This type of reactivity has been used in the literature to
promote carboamination of alkynes in the presence of Pt,[28]
Pd,[29] and Au[30] catalysts. While reaction yields were lower than
those for similar compounds synthesized using nBuLi,[20] this
new reactivity unlocks the potential to target more exotic donor/
acceptor ligands that might not be stable in the presence of a
strong nucleophile. Furthermore, symmetric bis-alkynyl by-prod-
ucts, formed by ligand scrambling, were not observed in the
synthesis of 3a and 3c, regardless of the stoichiometry of the
second alkynyl used. All new Co(cyclam) compounds (1a–1e and
3a–c) are diamagnetic, consistent with a low spin CoIII center,
which enables the characterization of these compounds using
1H NMR. Additionally, these compounds were analyzed using ESI-
MS and elemental analysis.
Results and Discussion
Synthesis
The general synthesis of 4-ethynyl-N-alkyl-1,8-naphthalimide
(HC2NAPR) is illustrated in Scheme 3. It comprises the reaction
between 4-bromonaphthalic anhydride and appropriate RNH2
to yield 4-bromo-N-alkyl-1,8-naphthalimide, and the Sonoga-
shira coupling between the latter and trimethylsilylacetylene.
The preparations of 4-ethynyl-N-methyl-1,8-naphthalimide
(HC2NAPMe),[24]
(HC2NAP2–ethhex),[26] and 4-ethynyl-N-octyl-1,8-naphthalimide
(HC2NAPOct [8]
follow literature procedures. For 4-ethynyl-N-
4-ethynyl-N-2-ethylhexyl-1,8-naphthalimide
)
mesityl-1,8-naphthalimide (HC2NAPMes), the initial insertion of
H2NMes into the naphthalic anhydride requires 84 h of reflux
in ethanol, five times longer than any other derivative reported
herein. Desilylation of TMSC2NAPMes formed HC2NAPMes in high
yield and dimerized NAPMesC4NAPMes as a minor by-product.
Formation
of
4-ethynyltrimethylsilyl-N-1-ethylpropyl-1,8-
naphthalimide (TMSC2NAPPen) occurred within 20 min at room
temperature; longer reaction times or extra heating resulted in
degradation and formation of NAPPenC4NAPPen. Synthetic de-
tails for both HC2NAPMes and HC2NAPPen are provided in the
ESI.
Scheme 3. i.) 3 equiv. H2NR, ethanol/2-propanol, reflux, 18–84 h; ii.) 2–3 equiv. HC2SiMe3, iPr2NH, 2 mol-% CuI, 2 mol-% Pd(PPh3)2Cl2, 20 min-2 h; iii.) excess
K2CO3, MeOH, 30 min.
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Scheme 4. i.) 1.1 equiv. HC2NAPMes, Et3N, CH3OH:THF, reflux, 18 h; ii.) 5 equiv. AgOTf, NCCH3, reflux, 16 h; iii.) 4 equiv. HC2Ar, Et3N, NCCH3, reflux, 24 h.
Molecular Structures
Table 1. Selected bond lengths [Å] and angles [°] for compounds [1a]+, [1c]+
and [3b]+.
Single crystals of 1a, 1c and 3b were grown via slow diffusion
of a less polar solvent into a polar concentrated solution of the
respective compound; the molecular structures of cations are
shown in Figure 1, Figure 2, and Figure 3, respectively. Selected
bond lengths and angles are provided in Table 1, while the
crystal data are listed in Table S1 (ESI). Single crystal structures
of HC2NAPMes and [Et3NC2H2NAPMes]OTf were determined as
well, and the details are provided in the ESI.
[1a]+
[1c]+
[3b]+
Co1–C1
Co1–N2
Co1–N3
Co1–N4
Co1–N5
Co1–Cl1
C1–C2
Cl1–Co–C1
C1′–Co–C1
Co–C1–C2
C1–C2–C3
1.859(3)
1.990(2)
1.973(2)
1.971(2)
1.983(2)
2.3154(5)
1.204(3)
176.76(8)
–
1.866 (5)
1.974 (4)
1.937 (4)
1.981 (4)
2.019 (4)
2.317 (3)
1.213 (5)
179.4 (3)
–
1.933(4)
1.982(4)
1.972(3)
–
–
–
1.210(5)
–
180.0
171.1(4)
170.4(4)
174.0(2)
176.5(2)
177.4 (7)
178.6 (6)
The Co centers of 1a, 1c and 3b assume pseudo-octahedral
geometries with the alkynyl and Cl/alkynyl trans- to each other.
Consistent with previous studies, the Co–C1 bond length is sig-
nificantly longer in the bis-NAPMes species, 3b [1.933(4) Å], com-
pared to the mono-NAPMes, 1a [1.859(3) Å], which can be attrib-
uted to the trans-influence as the increased donor strength pro-
vided by the alkynyl compared to the Cl in the axial position
results in a weaker bond.[19,21,22,31–33] The influence of the elec-
tron withdrawing/donating character of the alkynyl ligand on
the Co–C1 bond length can be observed across the literature
with [Co(cyclam)(C2CF3)2]+ (1.917)[34] < [Co(cyclam)(C2C6F5)2]+
Figure 1. ORTEP plot of cation [1a]+ at 30 % probability level; chloride coun-
terions, hydrogen atoms, disorder, and solvent molecules are omitted for clar-
ity.
(1.926)[22]
< 3b (1.933) <
[Co(cyclam)(C2C6H4-4-NMe2)2]+
(1.942)[21] < [Co(cyclam)(C2Ph)2]+ (2.001).[35] The electron with-
drawing species (–CF3, C6F5, and -NAPMes) have notably short-
ened bond lengths (Co–C) compared to the electron donating
groups [–NMe2 and –N(Ph-4-OMe)2] due to reduced antibond-
ing contribution from the π(C≡ C) to the Co dπ.[19,31,36]
Figure 2. ORTEP plot of cation [1c]+ at 30 % probability level; chloride coun-
terions, hydrogen atoms, disorder, and solvent molecules are omitted for clar-
ity.
Crystallographic data consistently shows the mesityl group
perpendicular to the naphthalimide ligand (Figure 1 and Fig-
ure 3), suggesting a sterically rigid structure. In contrast, flexible
alkyl chains as seen in NAPPen or NAPiPr can readily rotate, leav-
ing the imido carbonyls more accessible to nucleophilic attack.
Space filling models of [1a]+ and [1c]+ (Figure S3, ESI) illustrate
how the methyl groups on the mesityl lock the ring into place.
Figure 3. ORTEP plot of cation [3b]+ at 30 % probability level (one of two
crystallographically independent cations is shown); triflate counterions,
hydrogen atoms, and solvent molecules are omitted for clarity.
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Voltammetry
quasi-reversible oxidation couple at 0.22 V for the complex 3a
is assigned to the donor (–C6H4-4-NMe2) based on related litera-
ture examples of [Co(cyclam)(C2C6H4-4-NMe2)2]+ and [Co-
(cyclam)(C2C6H4-4-NMe2)(C2C6F5)]+.[22] Consistent with observa-
tions for [Co(cyclam)(C2NAPiPr)(C2C6H4-4-NMe2)]Cl,[20] this as-
signment suggests that the HOMO and LUMO for compound
3a reside on the donor and acceptor, respectively, and the elec-
trochemical HOMO-LUMO gap [Eg = E1/2(D) – E1/2(A)] can be
estimated as 1.88 V.
The CVs of compounds 1a, 3a, 3b, and HC2NAPMes are shown
in Figure 4, and all exhibit a reversible reduction (A) based on
the NAPMes ligand. The Co containing species (1a and 3a–3c)
undergo three Co based events: one irreversible 1e– oxidation
(Co+4/+3) and two irreversible 1e– reductions (Co+3/+2) and
(Co+2/+1) shown in the Figure S4 (ESI). The electrode potentials
for these couples are listed in Table 2. Comparison of mono-
alkynyl (1a) to the bis-alkynyl species (3a–c), reveals that the
first Co reduction shifts to significantly more negative potentials
upon addition of a second alkynyl. This trend is consistent with
previous observations and is attributed to the increased donor
strength of an alkynyl vs. a chloro in the axial position.[20] Com-
parison of the HC2NAPMes reduction potential (–1.52 V) to those
of 1a and 3a–c validates the assignment of the reversible re-
duction at –1.66 V being localized on the naphthalimide moi-
ety. Furthermore, it is clear from Figure 4 that 3b undergoes a
reversible 2e– NAPMes-based reduction as the current at –1.66 V
is approximately twice of those for 1a, 3a and HC2NAPMes. The
UV/Vis and Emission Spectra
Absorption and emission spectra were collected at room tem-
perature in CH2Cl2 under ambient conditions and λmax for these
spectra were recorded for 1a, 3a–c, TMSC2NAPMes, HC2NAPMes
,
[Et3NC2H2NAPMes]OTf and NAPMesC4NAPMes in Table 3. UV/Vis
spectra of all Co-based compounds are shown in Figure 5 (1a
and 3a–c), while those of TMSC2NAPMes, [Et3NC2H2NAPMes]OTf
and NAPMesC4NAPMes are given in Figure S5 (ESI). The absorp-
tion spectrum of TMSC2NAPMes features an intense peak at
360 nm, which is attributed to the π–π* transition localized on
NAPMes [8,20]
All Co-based compounds, 1a and 3a–c, display
.
broad absorption bands around 400 nm. TD-DFT calculations
performed on related compounds, [Co(cyclam)(C2NAPiPr)Cl]Cl,
[Co(cyclam)(C2NAPiPr)(C2C6H4-4-NMe2)]Cl and [Co(cyclam)-
(C2NAPiPr){C2C6H4-4-N(Ph-4-OMe)2}]Cl, indicate that this transi-
tion is predominantly a NAPMes based π–π* transition.[20] This
Table 3. Absorption and emission maxima (λ/nm) in CH2Cl2.
Compound
λabs
λem/λex
1a
3a
3b
3c
396
399
401
397
358/376
351/368
395/425
350
441/390
441/390
433/390
441/390
399/360
405/340
439/390
410/330
TMSC2NAPMes
HC2NAPMes
NAPMesC4NAPMes
[Et3NC2H2NAPMes]OTf
Figure 4. Cyclic voltammograms of 1a, 3a, 3b and HC2NAPMes vs. Fc/Fc+ in
1.0 mM NCCH3 solutions with 0.1 M [Bu4N][PF6] as the supporting electrolyte.
Table 2. Electrode potentials [V] for 1a, 3a, 3b, 3c, and HC2NAPMes [a]
.
Compound
E
1/2(D)
E
1/2(A)
–1.69 (0.10)
0.22 (0.07) –1.66 (0.06)
E ) E ) E )
pc(Co+3/+2 pc(Co+2/+1 pa(Co+4/+3
1a
3a
3b
–
–1.47
–2.15
–2.16
–1.85
–
–2.19
–2.26
–2.32
–2.30
–
0.66
0.73
0.89
1.17
–
–
–
–
–1.66 (0.08)
–1.66 (0.08)
–1.52 (0.06)
3c
HC2NAPMes
[a] Reported vs. Fc+/0 in NCCH3 with 0.1
M [Bu4N][PF6] as the supporting
electrolyte. Peak separations (Epa – Epc) for reversible couples are shown in
Figure 5. Absorption spectra of 1a (black), 3a (red), 3b (green), and 3c (blue)
brackets.
in CH2Cl2.
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assignment is also consistent with PtII(PnBu3)2(C2NAPOct) type Conclusion
complexes reported by Weinstein and co-workers, where the
Described in this contribution are several new [CoIII(cyclam)-
(C2NAPR)Cl]+ type complexes (R = Mes, Me, Pen, 2-ethhex, Oct)
that exhibit improved crystallinity and reactivity over
[CoIII(cyclam)(C2NAPiPr)Cl]+.[20] Careful tuning of the alkyl group
on the naphthalimide moiety revealed that –C2NAPMes based
complexes performed the best in the aforementioned catego-
ries. The increased stability afforded by the mesityl group allows
for selective synthesis of the [CoIII(cyclam)(C2NAPMes)(C2Ar)]+
type complexes under weak base conditions through a triflate
intermediate. Furthermore, the perpendicular orientation of the
mesityl ring in respect to the naphthalimide group prevents
π–π stacking thereby increasing solubility and crystallinity.
These encouraging results suggest that possible synthetic strat-
egies for the next generation of D-B-A complexes include i)
Hagihara coupling (CuI/organic amine) as a variation of the de-
hydrohalogenation reactions (used to couple arylalkynyls to co-
balamin[39]) and ii) organo-tin activated arylalkynyls (used by
Lewis and co-workers[12,40] to synthesize trans-RuII acetylides).
lowest energy transition was observed at 430 nm and was
attributed to mixed metal-ligand-to-ligand charge transfer
(ML/L′CT).[8] Generally, CoIII(cyclam) acetylides display a d-d
transition around 450–500 nm, with higher energy transitions
occurring for the bis-acetylide complexes and the lower energy
for the mono-acetylides.[19,21,22,31,32,36,37] However, only com-
pound 1a has a discernible d-d transition at 480 nm, suggesting
the broad π–π*(NAPMes) transition obscures the d-d peaks for
3a–c (Figure 5). Based on previous work on [Co(cyclam)-
(C2NAPiPr)(C2C6H4-4-NMe2)]Cl,[20] the sharp peak at 287 nm ob-
served for compound 3a was assigned to the π–π* transition
localized on the donor ligand (–C6H4-4-NMe2).
Use of a simple chromophore as the acceptor allows for anal-
ysis of steady-state emission, which may reveal the effect the
CoIII(cyclam) bridge and the donor (–C6H4-4-NMe2) have on the
acceptor (NAPMes) emission. As illustrated by the normalized
emission spectra of 1a, 3a and TMSC2NAPMes in Figure 6, the
emission profiles of 1a and 3a–c resemble those of the X-
C2NAPMes species (X = TMS or H), but were significantly red-
shifted (ca. 50 nm). The relatively small Stokes shift between
λabs and λem suggests that the observed emission originates
from the excited state around 400 nm. Furthermore, the similar-
ity between the emission of 1a and 3a suggests that the C6H4-
Experimental Section
Materials: Literature procedures were followed in the preparations
of [Co(cyclam)Cl2]Cl,[41] 4-ethynyl-N-methyl-1,8-naphthalimide,[24] 4-
4-NMe2 donor does not significantly affect the electronic states ethynyl-N-2-ethylhexyl-1,8-naphthalimide,[26] and 4-ethynyl-N-octyl-
1,8-naphthalimide.[8] Diisopropylamine and triethylamine were pur-
chased from ACROS Organics and Fisher Chemical, respectively, and
distilled from potassium hydroxide before use. 4-Ethynyl-N,N-di-
methylaniline was purchased from Sigma Aldrich. Phenylacetylene
was purchased from GFS Chemicals. All alkynylation reactions were
carried out using Schlenk techniques under dry N2.
of Co bound -C2NAPMes. Similar findings were reported for the
analogous compounds bearing NAPiPr, with fluorescent quan-
tum yields (Φfl) in CH2Cl2 on the order of 0.43–0.66 % for the
CoIII(cyclam)(C2NAPiPr) compounds and 42 % for HC2NAPiPr.[20]
The dimerized forms of NAPR ligand, namely NAPR-C4-NAPR (R =
nBu or Ph), were reported to have Φfl on the order of 83 % and
101 %, respectively.[38] While quantum yields were not recorded
for this series, compounds 1a and 3a–c were observed to have
extremely weak emission compared to the organic species
listed in Table 3. Quenching of fluorophore emission due to the
presence of a metal has also been observed by the Weinstein
Physical Measurements: UV/Vis-NIR spectra were obtained with a
JASCO V-670 UV/Vis-NIR spectrophotometer. Infrared spectra were
obtained on a JASCO FT-IR 6300 spectrometer via ATR on a ZnSe
crystal. ESI-MS was carried out on an Advion Mass Spectrometer. 1H
NMR spectra were recorded on a Varian INOVA300 NMR with chemi-
cal shifts (δ) referenced to the solvent signal (CD3OD at 4.88 and
3.31 ppm; CDCl3 at 7.26 ppm). Cyclic voltammograms were re-
group, who recorded a Φfl of 5.5 % for a PtII(PnBu3)2(C2NAPOct
)
D-B-A species,[8,9] and by McAdam and co-workers who re-
corded a Φfl of 0.11 % and 0.24 % for naphthalimide species
linked to ferrocene.[24]
corded in 0.1
M nBu4NPF6 and 1.0 mM cobalt species solution
(CH3CN, Ar degassed) using a CHI620A voltammetric analyzer with
a glassy carbon working electrode (diameter = 2 mm), Pt-wire coun-
ter electrode, and an Ag/AgCl reference electrode with ferrocene
used as an external reference. Emission studies were measured on
a Varian Cary Eclipse fluorescence spectrophotometer.
Synthesis of [Co(cyclam)(C2NAPMes)Cl]Cl (1a): [Co(cyclam)Cl2]Cl
(645 mg, 1.77 mmol) was dissolved in 50 mL CH3OH to which a
10 mL solution of THF containing 4-ethynyl-N-mesityl-1,8-naphthal-
imide (677 mg, 2.0 mmol) was added and purged with N2. Upon
addition of Et3N (4.0 mL, 30 mmol) the solution darkened and was
refluxed for 18 h. Silica plug purification with CH3OH/CH2Cl2 (v/v,
1:9) eluted the product as an orange band. Recrystallization from
CH3OH/CH2Cl2 (v/v, 1:1) and ether yielded 600 mg of 1 as an orange
solid (51 % based on [Co(cyclam)Cl2]Cl). ESI-MS: [M]+, 630.2; 1H NMR
(300 MHz, [D]methanol) δ = 9.08 (d, J = 9.0 Hz, 1H), 8.65 (d, J =
7.4 Hz, 1H), 8.54 (d, J = 7.9 Hz, 1H), 8.04 (d, J = 7.9 Hz, 1H), 8.00–
7.90 (m, 1H), 7.06 (s, 2H), 5.38 (s, 4H), 3.10–2.90 (m, 4H), 2.89–2.64
(m, 14H), 2.57 (d, J = 13.3 Hz, 2H), 2.37 (s, 3H), 2.04 (s, 6H). Visible
M
–1 cm–1)): 396 (33,400), 480 (534); IR (cm–1):
Figure 6. Normalized emission spectra of 1a vs. 3a and TMSC2NAPMes in
CH2Cl2.
spectrum, λmax (nm, ε (
ν = O: 1652 (s), 1700 (s); C≡ C: 2103 (s). Elem. Anal. found (calcd.) for
˜
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C34H44N5O3CoCl4 (1a·H2O·CH2Cl2): C, 53.34 (52.93); H, 5.79 (5.75); N,
9.47 (9.08).
Synthesis of [Co(cyclam)(C2NAPMes)(C2-4-C6H4NMe2)]Cl (3a): In a
50 mL round-bottomed flask, 2a (95 mg, 0.11 mmol) was dissolved
in 20 mL CH3CN and purged with N2. After addition of Et3N (0.9 mL,
6.6 mmol) and HC2-C6H4-NMe2 (62 mg, 0.43 mmol) the solution was
refluxed for 24 h. Purification over a silica plug (SiO2, CH3OH/EtOAc
v/v, 1:5) eluted the desired product as a light orange band. Recrys-
tallization from CH3CN/CH2Cl2 (v/v, 1:1) and ether yielded 43 mg of
3a as a light orange solid (39 % based on 2a). ESI-MS: [M]+, 741.3;
1H NMR (300 MHz, [D]methanol) δ = 9.22 (d, J = 8.4 Hz, 1H), 8.66
(d, J = 6.9 Hz, 1H), 8.55 (d, J = 8.3 Hz, 1H), 8.06 (d, J = 7.7 Hz, 1H),
Synthesis of [Co(cyclam)(C2NAPPen)Cl]Cl (1c): [Co(cyclam)Cl2]Cl
(99.5 mg, 0.27 mmol) was dissolved in 50 mL CH3OH containing
0.7 mL (5.0 mmol) Et3N. The solution was purged with N2, then
4-ethynyltrimethylsilyl-N-1-ethylpropyl-1,8-naphthalimide (115 mg,
0.32 mmol) was added and the solution was refluxed for 16 h. Silica
plug purification with CH3OH/CH2Cl2 (v/v, 1:5) eluted the product
as an orange band. Recrystallization from CH3OH/CH2Cl2 (v/v, 1:1)
and ether yielded 79 mg of 1c as an orange crystalline solid (47 %
based on [Co(cyclam)Cl2]Cl). ESI-MS: [M]+, 584.2; 1H NMR (300 MHz,
[D]methanol) δ = 8.97 (d, J = 7.2 Hz, 1H), 8.58 (d, J = 6.8 Hz, 1H),
8.47 (d, J = 7.6 Hz, 1H), 7.97 (d, J = 7.7 Hz, 1H), 7.94–7.82 (m, 1H),
5.33 (s br, 4H), 5.06–5.01 (m, 1H), 2.88–2.69 (m, 14H), 2.26 (dd, J =
13.8, 7.5 Hz, 2H), 2.12–1.95 (m, 4H), 1.89 (dd, J = 13.5, 5.9 Hz, 2H),
1.77–1.65 (m, 2H), 0.87 (t, J = 7.4 Hz, 6H). Visible spectrum, λmax
7.98–7.91 (m, 1H), 7.38 (d,
J = 8.8 Hz, 2H), 7.06 (s, 2H),
6.72 (d, J = 8.5 Hz, 2H), 4.86 (s, 4H), 2.94 (s, 6H), 2.76–2.68 (m, 12H),
2.65–2.52 (m, 8H), 2.37 (s, 3H), 2.06 (s, 6H). Visible spectrum, λmax
(nm, ε (
(s), 1699 (s); C≡ C: 2087 (w). Elem. Anal. found (calcd.) for
45H52N6O5CoCl2SF3 (3a·CH2Cl2): C, 55.06 (55.39); H, 5.60 (5.37); N,
M
–1 cm–1)): 287 (66,000), 399 (34,300); IR (cm–1): ν = O: 1654
˜
C
8.61 (8.99).
(nm, ε (
1684 (s); C≡ C: 2109 (s). Elem. Anal. found (calcd.) for
29.5H41N5O2CoCl3 (1c·0.5CH2Cl2): C, 53.51 (53.45); H, 6.61 (6.23); N,
M
–1 cm–1)): 391 (27,900), 483 (245); IR (cm–1): ν = O: 1647 (s),
˜
Synthesis of [Co(cyclam)(C2NAPMes)2]Cl (3b): In a 100 mL round-
bottomed flask, 2a (150 mg, 0.16 mmol) was dissolved in 60 mL
CH3CN and purged with N2. After addition of Et3N (1.5 mL,
7.9 mmol) and HC2NAPMes (120 mg, 0.35 mmol) the solution was
refluxed for 16 h. Purification over a silica plug (SiO2, CH3OH/CH2Cl2
v/v, 1:7) eluted the desired product as a yellow band. Recrystalliza-
tion from CH3CN/CH2Cl2 (v/v, 1:1) and ether yielded 20 mg of 3b
as a yellow solid (11 % based on 2a). ESI-MS: [M]+, 935.4; 1H NMR
(300 MHz, [D]methanol) δ = 9.24 (d, J = 8.8 Hz, 2H), 8.68
(d, J = 7.5 Hz, 2H), 8.58 (d, J = 7.9 Hz, 2H), 8.11 (d, J = 8.3 Hz, 2H),
8.01–7.93 (m, 2H), 7.07 (s, 4H), 5.61 (s, 4H), 3.13–3.06 (m, 3H), 2.85–
2.66 (m, 17H), 2.37 (s, 6H), 2.07 (s, 12H). Visible spectrum, λmax (nm,
C
10.72 (10.56).
Synthesis of [Co(cyclam)(C2NAP2–ethhex)Cl]Cl (1d): [Co(cyc-
lam)Cl2]Cl (150 mg, 0.41 mmol) was dissolved in 80 mL CH3OH to
which a 10 mL solution of THF containing 4-ethynyl-N-2-ethylhexyl-
1,8-naphthalimide (138 mg, 0.41 mmol) was added and purged with
N2. Upon addition of Et3N (1.0 mL, 7.5 mmol) the solution darkened
and was refluxed for 18 h. Silica plug purification with CH3OH/
CH2Cl2 (v/v, 1:6) eluted the product as an orange band. Recrystalli-
zation from CH3OH/CH2Cl2 (v/v, 1:1) and ether yielded 122 mg of
1d as an orange solid (45 % based on [Co(cyclam)Cl2]Cl). ESI-MS:
[M]+, 626.3; 1H NMR (300 MHz, [D]methanol) δ = 8.98 (d, J = 8.3 Hz,
1H), 8.58 (d, J = 6.9 Hz, 1H), 8.47 (d, J = 7.4 Hz, 1H), 7.97 (d, J =
7.8 Hz, 1H), 7.90–7.83 (m, 1H), 5.34 (s, 4H), 4.10 (d, J = 7.2 Hz, 2H),
2.93–2.71 (m, 16H), 2.01 (d, J = 16.7 Hz, 4H), 1.73–1.68 (m, 1H), 1.37
(dd, J = 14.8, 7.2 Hz, 8H), 1.04–0.83 (m, 6H). Visible spectrum, λmax
ε (M
–1 cm–1)): 401 (59,900); IR (cm–1): ν = O: 1655 (m), 1698 (m);
˜
C≡ C: 2086 (w). Elem. Anal. found (calcd.) for C61H63N7O7CoCl4SF3
(3b·2CH2Cl2·CH3CN): C, 56.06 (56.53); H, 5.06 (4.90); N, 7.41 (7.57).
Synthesis of [Co(cyclam)(C2NAPMes)(C2Ph)]Cl (3c): In a 100 mL
round-bottomed flask, 2a (150 mg, 0.16 mmol) was dissolved in
30 mL CH3CN and purged with N2. After addition of Et3N (1.5 mL,
7.9 mmol) and HC2Ph (0.1 mL, 11 mmol) the solution was refluxed
for 16 h. Purification over a silica plug (SiO2, CH3OH/CH2Cl2 v/v, 1:8)
eluted the desired product as a yellow band. Recrystallization from
CH3CN/CH2Cl2 (v/v, 1:1) and ether yielded 81 mg of 3c as a yellow
solid (60 % based on 2a). ESI-MS: [M]+, 698.3; 1H NMR (300 MHz,
[D]methanol) δ = 9.09 (d, J = 7.1 Hz, 1H), 8.66 (d, J = 6.3 Hz, 1H),
8.54 (d, J = 8.1 Hz, 1H), 8.06 (d, J = 6.9 Hz, 1H), 8.03–7.92 (m, 2H),
7.52 (d, J = 8.8 Hz, 1H), 7.35–7.16 (m, 3H), 7.06 (s, 2H), 5.31 (s br,
4H), 3.02–2.69 (m, 18H), 2.60–2.54 (m, 2H), 2.37 (s, 3H), 2.06 (s, 6H).
(nm, ε (
1691 (s); C≡ C: 2101 (s). Elem. Anal. found (calcd.) for
35H56N5O4CoCl8 (1d·2H2O·3CH2Cl2): C, 43.96 (44.09); H, 5.75 (5.92);
M
–1 cm–1)): 392 (24,500), 480 (253); IR (cm–1): ν = O: 1646 (s),
˜
C
N, 7.99 (7.35).
Synthesis of [Co(cyclam)(C2NAPOct)Cl]Cl (1e): [Co(cyclam)Cl2]Cl
(500 mg, 1.4 mmol) was dissolved in 90 mL CH3OH and 4 mL Et3N
(30 mmol) to which 4-ethynyl-N-octyl-1,8-naphthalimide (513 mg,
1.5 mmol) was added and purged with N2. The solution was re-
fluxed for 18 h. Silica plug purification with CH3OH/CH2Cl2 (v/v, 1:5)
eluted the product as an orange band. Recrystallization from
CH3OH/CH2Cl2 (v/v, 1:1) and ether yielded 345 mg of 1e as an or-
ange solid (63 % based on [Co(cyclam)Cl2]Cl). ESI-MS: [M]+, 626.3;
1H NMR (300 MHz, [D]methanol) δ = 8.92 (d, J = 8.2 Hz, 1H), 8.53
(d, J = 7.1 Hz, 1H), 8.42 (d, J = 7.8 Hz, 1H), 7.93 (d, J = 7.7 Hz, 1H),
7.89–7.79 (m, 1H), 5.34 (s, 4H), 4.17–4.06 (m, 2H), 2.99–2.67 (m, 18H),
2.10–1.98 (m, 2H), 1.74–1.70 (m, 2H), 1.42–1.29 (m, 10H), 0.90 (d, J =
Visible spectrum, λmax (nm, ε (M
–1 cm–1)): 397 (29,400); IR (cm–1):
ν = O: 1655 (s), 1699 (s); C≡ C: 2096 (s). Elem. Anal. found (calcd.) for
˜
C47H55N6O5CoCl6SF3 (3c·3CH2Cl2·CH3CN): C, 49.09 (49.32); H, 4.23
(4.84); N, 6.98 (7.34).
X-ray Crystallographic Analysis: Single crystals of 1a were ob-
tained from the slow diffusion of diethyl ether into a CH2Cl2/CH3OH
(v/v, 1:1) solution. Single crystals of 1c were grown from slow diffu-
sion of diethyl ether/hexanes (v/v 2:1) into a CH3OH solution. Single
crystals of 3b were grown from slow diffusion of hexanes into a
CH2Cl2/CH3OH (v/v, 2:1) solution. Single crystals of HC2NAPMes were
grown from slow evaporation of a CH2Cl2/hexanes (v/v 1:2) solution.
Single crystals of [Et3NC2H2NAPMes]OTf were grown from slow diffu-
sion of diethyl ether into a CH3CN/MeOH (v/v 1:1) solution. X-ray
diffraction data for 1a, 1c and [Et3NC2H2NAPMes]OTf was obtained
on a Bruker Quest diffractometer with Mo-Kα radiation (λ =
0.71073 Å) at 150K. X-ray diffraction data for 3b and HC2NAPMes
were obtained on a Bruker Quest diffractometer with Cu-Kα radia-
tion (λ = 1.54178 Å) at 150K. Data were collected; reflections were
7.4 Hz, 3H). Visible spectrum, λmax (nm, ε (M
–1 cm–1)): 393 (23,900),
482 (228); IR (cm–1): ν = O: 1647 (s), 1684 (s); C≡ C: 2110 (s). Elem.
˜
Anal. found (calcd.) for C34H50N5O2CoCl6 (1e·2CH2Cl2): C, 48.77
(49.06); H, 6.13 (6.05); N, 8.92 (8.41).
Synthesis of [Co(cyclam)(C2NAPMes)(NCCH3)]OTf2 (2a): [Co-
(cyclam)(C2NAPMes)Cl]Cl, compound 1a (323 mg, 0.49 mmol) was
dissolved in 60 mL of CH3CN and purged with N2. Upon addition
of AgOTf (620 mg, 2.41 mmol) the solution was refluxed for 16 h.
The solution was filtered through celite with CH3CN and concen-
trated. Recrystallization from CH3CN and ether yielded 287 mg of
2a as a yellow solid (63 % based on 1a). ESI-MS: [M – OTf]+, 744.2.
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indexed and processed using APEX3.[42] The space groups were as-
signed and the structures were solved by direct methods using
XPREP within the SHELXTL suite of programs[43] and refined
using Shelxl and Shelxle.[44] Additional crystallographic data for
HC2NAPMes, [Et3NC2H2NAPMes]OTf, 1a, 1c and 3b are provided in
Table S1 and Table S2 and in the SI (handling of H atoms, descrip-
tion of disorder, twinning and special refinement details).
[15] 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, 3202–3203; A. S.
Blum, T. Ren, D. A. Parish, S. A. Trammell, M. H. Moore, J. G. Kushmerick,
G.-L. Xu, J. R. Deschamps, S. K. Pollack, R. Shashidhar, J. Am. Chem. Soc.
2005, 127, 10010–10011; A. K. Mahapatro, J. Ying, T. Ren, D. B. Janes,
Nano Lett. 2008, 8, 2131–2136; Y. Tanaka, Y. Kato, T. Tada, S. Fujii, M.
Kiguchi, M. Akita, J. Am. Chem. Soc. 2018, 140, 10080–10084; B. Kim,
J. M. Beebe, C. Olivier, S. Rigaut, D. Touchard, J. G. Kushmerick, X.-Y. Zhu,
C. D. Frisbie, J. Phys. Chem. C 2007, 111, 7521–7526.
[16] F. B. Meng, Y. M. Hervault, Q. Shao, B. H. Hu, L. Norel, S. Rigaut, X. D.
Chen, Nat. Commun. 2014, 5, Art. 3023; H. Zhu, S. J. Pookpanratana, J. E.
Bonevich, S. N. Natoli, C. A. Hacker, T. Ren, J. S. Suehle, C. A. Richter, Q.
Li, ACS Appl. Mater. Interfaces 2015, 7, 27306–27313.
CCDC 1937327 (for 1a), 1937328 (for 1c), 1937329 (for 3b), 193730
(for HC2NAPMes), and 193731 (for [Et3NC2H2NAPMes]OTf) contain the
supplementary crystallographic data for this paper. These data can
be obtained free of charge from The Cambridge Crystallographic
Data Centre.
[17] T. Ren, Chem. Commun. 2016, 52, 3271–3279.
[18] S. D. Banziger, T. Ren, J. Organomet. Chem. 2019, 885, 39–48.
[19] S. D. Banziger, T. D. Cook, S. N. Natoli, P. E. Fanwick, T. Ren, J. Organomet.
Chem. 2015, 799–800, 1–6.
[20] S. D. Banziger, X. Li, J. Valdiviezo, M. Zeller, P. Zhang, D. N. Beratan, I.
Rubtsov, T. Ren, Inorg. Chem. 2019, 58, 15487–15497.
[21] S. N. Natoli, M. Zeller, T. Ren, Inorg. Chem. 2016, 55, 5756–5758.
[22] S. N. Natoli, M. Zeller, T. Ren, Inorg. Chem. 2017, 56, 10021–10031.
[23] C. J. McAdam, A. R. Manning, B. H. Robinson, J. Simpson, Inorg. Chim.
Acta 2005, 358, 1673–1682.
[24] C. J. McAdam, J. L. Morgan, B. H. Robinson, J. Simpson, P. H. Rieger, A. L.
Rieger, Organometallics 2003, 22, 5126–5136.
Acknowledgments
We gratefully acknowledge financial support from the National
Science Foundation (CHE 1764347 for research and CHE
1625543 for X-ray diffractometers). We would like to thank Lind-
sey A. Miller and Brandon L. Mash for assistance with X-ray data
collection. S. D. B. thanks Purdue University for a Cagiantas Fel-
lowship.
[25] C. J. McAdam, B. H. Robinson, J. Simpson, T. Tagg, Organometallics 2010,
29, 2474–2483.
[26] A. Saini, K. R. J. Thomas, RSC Adv. 2016, 6, 71638–71651.
[27] G. W. Fischer, Z. Chem. 1968, 8, 269–270.
Keywords: Cobalt · Dissymmetric complexes · Alkyne
ligands · Electrochemistry · Synthesis design
[28] T. Shimada, I. Nakamura, Y. Yamamoto, J. Am. Chem. Soc. 2004, 126,
10546–10547.
[29] S. Cacchi, G. Fabrizi, P. Pace, J. Org. Chem. 1998, 63, 1001–1011.
[30] X. Zeng, R. Kinjo, B. Donnadieu, G. Bertrand, Angew. Chem. Int. Ed. 2010,
49, 942–945; Angew. Chem. 2010, 122, 954.
[31] T. D. Cook, P. E. Fanwick, T. Ren, Organometallics 2014, 33, 4621–4624.
[32] E. C. Judkins, M. Zeller, T. Ren, Inorg. Chem. 2018, 57, 2249–2259; P. U.
Thakker, R. G. Aru, C. Sun, W. T. Pennington, A. M. Siegfried, E. C. Marder,
P. S. Wagenknecht, Inorg. Chim. Acta 2014, 411, 158–164.
[33] B. M. Oxley, B. Mash, M. Zeller, S. Banziger, T. Ren, Acta Crystallogr., Sect.
E 2018, 74, 522–529.
[34] P. U. Thakker, C. Sun, L. Khulordava, C. D. McMillen, P. S. Wagenknecht, J.
Organomet. Chem. 2014, 772, 107–112.
[35] W. A. Hoffert, M. K. Kabir, E. A. Hill, S. M. Mueller, M. P. Shores, Inorg.
Chim. Acta 2012, 380, 174–180.
[36] T. D. Cook, S. N. Natoli, P. E. Fanwick, T. Ren, Organometallics 2015, 34,
686–689.
[37] T. D. Cook, S. N. Natoli, P. E. Fanwick, T. Ren, Organometallics 2016, 35,
1329–1338; S. N. Natoli, T. D. Cook, T. R. Abraham, J. J. Kiernicki, P. E.
Fanwick, T. Ren, Organometallics 2015, 34, 5207–5209; S. N. Natoli, T. J.
Azbell, P. E. Fanwick, M. Zeller, T. Ren, Organometallics 2016, 35, 3594–
3603.
[38] Y. Liu, H.-Y. Wang, G. Chen, X.-P. Xu, S.-J. Ji, Aust. J. Chem. 2009, 62, 934–
940.
[39] M. Chrominski, A. Lewalska, D. Gryko, Chem. Commun. 2013, 49, 11406–
11408.
[40] M. Younus, N. J. Long, P. R. Raithby, J. Lewis, N. A. Page, A. J. P. White,
D. J. Williams, M. C. B. Colbert, A. J. Hodge, M. S. Khan, D. G. Parker, J.
Organomet. Chem. 1999, 578, 198–209.
[41] B. Bosnich, M. L. Tobe, G. A. Webb, Inorg. Chem. 1965, 4, 1109–1112.
[42] APEX3 v2016.9–0, Saint V8.34A, Saint V8.37A; 2016.
[43] SHELXTL suite of programs, version 6.14; 2000–2003; G. M. Sheldrick,
Acta Crystallogr., Sect. A 2008, 64, 112–122.
[1] M. R. Wasielewski, Chem. Rev. 1992, 92, 435–461.
[2] P. F. Barbara, T. J. Meyer, M. A. Ratner, J. Phys. Chem. 1996, 100, 13148–
13168; B. Albinsson, J. Mårtensson, J. Photochem. Photobiol. C 2008, 9,
138–155.
[3] A. Hagfeldt, M. Gratzel, Acc. Chem. Res. 2000, 33, 269–277.
[4] Y. Gabe, Y. Urano, K. Kikuchi, H. Kojima, T. Nagano, J. Am. Chem. Soc.
2004, 126, 3357–3367.
[5] J. L. Sessler, B. Wang, A. Harriman, J. Am. Chem. Soc. 1995, 117, 704–714.
[6] A. C. Benniston, A. Harriman, Chem. Soc. Rev. 2006, 35, 169–179.
[7] M. Delor, P. A. Scattergood, I. V. Sazanovich, A. W. Parker, G. M. Greetham,
A. J. H. M. Meijer, M. Towrie, J. A. Weinstein, Science 2014, 346, 1492–
1495.
[8] P. A. Scattergood, M. Delor, I. V. Sazanovich, O. V. Bouganov, S. A. Tikhom-
irov, A. S. Stasheuski, A. W. Parker, G. M. Greetham, M. Towrie, E. S. Davies,
A. J. H. M. Meijer, J. A. Weinstein, Dalton Trans. 2014, 43, 17677–17693.
[9] A. Haque, R. A. Al-Balushi, I. J. Al-Busaidi, M. S. Khan, P. R. Raithby, Chem.
Rev. 2018, 118, 8474–8597.
[10] C.-L. Ho, Z.-Q. Yu, W.-Y. Wong, Chem. Soc. Rev. 2016, 45, 5264–5295; P. J.
Low, M. I. Bruce, Adv. Organomet. Chem. 2001, 48, 71–288; B. Pigulski, N.
Gulia, S. Szafert, Eur. J. Org. Chem. 2019, 1420–1445; A. Triadon, G. Grel-
aud, N. Richy, O. Mongin, G. J. Moxey, I. M. Dixon, X. Yang, G. Wang,
A. Barlow, J. Rault-Berthelot, M. P. Cifuentes, M. G. Humphrey, F. Paul,
Organometallics 2018, 37, 2245–2262; A. Haque, R. A. Al-Balushi, M. S.
Khan, J. Organomet. Chem. 2019, 897, 95–106.
[11] S. Szafert, J. A. Gladysz, Chem. Rev. 2003, 103, 4175–4206; S. Szafert, J. A.
Gladysz, Chem. Rev. 2006, 106, PR1–PR33.
[12] N. J. Long, C. K. Williams, Angew. Chem. Int. Ed. 2003, 42, 2586–2617;
Angew. Chem. 2003, 115, 2690.
[13] J.-P. Launay, Chem. Soc. Rev. 2001, 30, 386–397; T. Ren, Organometallics
2005, 24, 4854–4870; K. Costuas, S. Rigaut, Dalton Trans. 2011, 40, 5643–
5658; Y. Tanaka, M. Akita, Coord. Chem. Rev. 2019, 388, 334–342.
[14] R. Dembinski, T. Bartik, B. Bartik, M. Jaeger, J. A. Gladysz, J. Am. Chem.
Soc. 2000, 122, 810–822; M. I. Bruce, P. J. Low, K. Costuas, J.-F. Halet, S. P.
Best, G. A. Heath, J. Am. Chem. Soc. 2000, 122, 1949–1962; Z. Cao, B. Xi,
D. S. Jodoin, L. Zhang, S. P. Cummings, Y. Gao, S. F. Tyler, P. E. Fanwick,
R. J. Crutchley, T. Ren, J. Am. Chem. Soc. 2014, 136, 12174–12183.
[44] G. M. Sheldrick, Acta Crystallogr., Sect. C 2015, 71, 3–8; C. B. Hübschle,
G. M. Sheldrick, B. Dittrich, J. Appl. Crystallogr. 2011, 44, 1281–1284.
Received: October 4, 2019
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© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim