Tris(2-pyridyl) Bismuthines: Coordination Chemistry, Reactivity, and Anion-Triggered Pyridyl Coupling

Article abstract of DOI:10.1021/acs.inorgchem.0c00579

A series of new tris(2-pyridyl) bismuthine ligands of the type [Bi(2-py′)₃] have been prepared, containing a range of substituents at various positions within their pyridyl rings (py′). They can act as intact ligands or, as a result of the low C-Bi bond energy, exhibit noninnocent reactivity in the presence of metal ions. Structural studies of Li⁺ and Ag⁺ complexes show that the coordination to metal ions using their pyridyl-N atoms and to anions using the Lewis acidity of their Bi(III) centers can be modified by the presence of substituents within the 2-pyridyl rings, especially at the 6- or 3-positions, which can block the donor-N or Lewis acid Bi sites. Electron withdrawing groups (like CF₃ or Br) can also severely reduce their ability to act as ligands to metal ions by reducing the electron donating ability of the pyridyl-N atoms. Noninnocent character is found in the reactions with Cu⁺ and Cu²⁺, resulting in the coupling of pyridyl groups to form bipyridines, with the rate of this reaction being dependent on the anion present in the metal salts. This leads to the formation of Bi(III)/Cu(I) complexes containing hypervalent [X₂Bi(2-R-py)]^- (X = Cl, Br) anions. Alternatively, the tris(2-pyridyl) bismuthine ligands can act as 2-pyridyl transfer reagents, transferring 2-py groups to Au(I) and Fe(II).

Full text of DOI:10.1021/acs.inorgchem.0c00579

pubs.acs.org/IC
Article
Tris(2-pyridyl) Bismuthines: Coordination Chemistry, Reactivity, and
Anion-Triggered Pyridyl Coupling
́
Alvaro García-Romero, Alex J. Plajer, Daniel Miguel, Dominic S. Wright, Andrew D. Bond,
́
́
Celedonio M. Alvarez,* and Raul García-Rodríguez*
Cite This: https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Read Online
sı
*
Metrics & More
Article Recommendations
Supporting Information
ACCESS
ABSTRACT: A series of new tris(2-pyridyl) bismuthine ligands of the type [Bi(2-py′)3]
have been prepared, containing a range of substituents at various positions within their
pyridyl rings (py′). They can act as intact ligands or, as a result of the low C−Bi bond
energy, exhibit noninnocent reactivity in the presence of metal ions. Structural studies of
Li+ and Ag+ complexes show that the coordination to metal ions using their pyridyl-N
atoms and to anions using the Lewis acidity of their Bi(III) centers can be modified by the
presence of substituents within the 2-pyridyl rings, especially at the 6- or 3-positions, which
can block the donor-N or Lewis acid Bi sites. Electron withdrawing groups (like CF3 or Br)
can also severely reduce their ability to act as ligands to metal ions by reducing the electron
donating ability of the pyridyl-N atoms. Noninnocent character is found in the reactions
with Cu+ and Cu2+, resulting in the coupling of pyridyl groups to form bipyridines, with the
rate of this reaction being dependent on the anion present in the metal salts. This leads to
the formation of Bi(III)/Cu(I) complexes containing hypervalent [X2Bi(2-R-py)]− (X = Cl, Br) anions. Alternatively, the tris(2-
pyridyl) bismuthine ligands can act as 2-pyridyl transfer reagents, transferring 2-py groups to Au(I) and Fe(II).
INTRODUCTION
■
Tripodal and facially coordinating ligands have found countless
applications in modern coordination, organometallic and
bioinorganic chemistry.1 The ubiquitous tris-pyrazolyl borates
constitute perhaps the best-known class of this type of ligands
(Figure 1a).2 These popular ligands are extremely versatile, as
their steric and electronic characteristics can be easily modified
through the introduction of substituents in their pyrazolyl
moieties. Although less well-studied, tris(2-pyridyl)-based
ligands have emerged as another important class of tripodal
ligands. Most studies in this area in the last 40 years have
focused on ligands of the type E(2-py)3 that contain lighter,
nonmetallic bridgehead atoms (E = CR, COR, CH, N, P, P =
O, etc.; 2-py = 2-pyridyl; Figure 1b).3 These ligands have found
a broad range of applications in similar areas to their tris-
pyrazolyl borate counterparts in coordination, catalysis, and
Figure 1. a) The tris-pyrazolyl borate ligand, b) “classical” tris(2-
pyridyl) ligands with nonmetallic bridgeheads, c) tris(2-pyridyl)
aluminates, and d) Bi[(6-Me-2-py)3], the only example of a
bismuthine tris(2-pyridyl) ligand. e) Introduction of a functional
group in the bismuthine framework to modulate Lewis acidity and
basicity, which in turn affects the cation and anion coordination ability
of the ligand.
organometallic and bioinorganic chemistry, including stoichio-
metric organic transformations and as models for the
coordination in enzymatic metal sites.4
More recently, attention has turned to tris(2-pyridyl)
arrangements containing heavier and more metallic bridgehead
atoms.5−20 The introduction of different main group elements
as the bridgehead is a simple and emerging strategy for
modifying the reactivity and coordination properties of
different types of ligands.21−23 The introduction of larger
(more electropositive) p-block bridgeheads can be used to
modify the electronic (donor) character and the ligand bite of
tris(2-pyridyl) ligands in a systematic way.24 This approach has
Received: February 22, 2020
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
© XXXX American Chemical Society
Inorg. Chem. XXXX, XXX, XXX−XXX
A

Inorganic Chemistry
pubs.acs.org/IC
Article
recently been shown to be of value in modulating the catalytic
activity of transition metal complexes of Group 15 tris(2-
pyridyl) ligands.25
unsubstituted bismuthine ligand (which we were unable to
obtain) to the presence of 6-Me groups in the pyridyl rings, as
their electron-donating nature prevented reductive elimination
of 2,2′-bipyridine and the formation of Bi metal. In the current
study we first explored the synthesis of other tris(2-pyridyl)
ligands containing electron-withdrawing substituents at the 6-
position of the pyridyl ring in order to assess their stability in
comparison to 1. In addition to modifying the donor strength
and steric profile of the pyridyl coordination site of the
bismuthine ligand, we reasoned that the introduction of
electron-withdrawing groups should also result in increased
Lewis acidity at the bismuth center. The preparation of the
new ligands [Bi(6-R-2-py)3] [R = Br (2), CF3 (3), Ph (4)] was
straightforward from the reaction of BiCl3 and the correspond-
ing 2-lithio-6-substituted-pyridine (2-Li-6-R-py) in THF or
Et2O at −78 °C (see Scheme 1a). The lithiation time and
One further potential consequence of incorporating more
electropositive (metallic and semimetallic) bridgehead atoms is
an increase in the polarity of the bridgehead atom−C bonds to
the pyridyl groups. In contrast to more robust tris(2-pyridyl)
borate ligands,26−28 tris(2-pyridyl)aluminates [RAl(2-py)3]−
(Figure 1c) react as bases with H2O, alcohols, or carboxylic
acids in a controlled manner, providing an interesting route to
new aluminates containing additional donor functionality.29−31
This behavior has led to new applications as thermally stable
pyridyl-transfer reagents as well as reagents for the rapid NMR
spectroscopic determination of the enantiomeric excess (ee) of
chiral alcohols.32−34
Although the coordination chemistry of tris(2-pyridyl)
ligands E(2-py)3 of the lighter Group 15 elements (E = N,
P, As) has been extensively studied,35−49 it was only very
recently that heavier counterparts containing Sb and Bi have
been introduced. Most relevant to the current study, we
showed that 6-methyl substitution at the pyridine rings allows
the synthesis of the stable ligand [Bi(6-Me-2-py)3] (1) (Figure
1d), which is to date the only example of a tris(2-pyridyl)
bismuthine reported. Our studies on the coordination
chemistry of this new ligand were, however, limited to Cu(I)
complexes, and very little is known about the coordination
characteristics or reactivity of these species.25
Scheme 1. a) Synthesis of 6-Substituted Tris(2-pyridyl)
Ligands 2−4 and b) Synthesis of 3-, 5-, and Unsubstituted
a
Tris(2-pyridyl) Ligands 5−7
Due to the low toxicity50−52 and the highly Lewis acidic
character of bismuth, the chemistry of organobismuth
compounds is experiencing a resurgence of interest, finding
different applications in catalysis, activation reactions, and
materials chemistry.53−61 Nonetheless, bismuthine ligand
chemistry remains relatively underdeveloped in comparison
to that of lighter Group 15 based ligands, in part due to the
weakness of element−Bi bonds, which can make them
thermally unstable. Illustrating the potential in this area,
Gabbai and Limberg have recently developed amphiphilic
bismuthine ligands of the type PBiP (P = phenylenephosphino
groups), which utilize the Lewis acidity of Bi(III) to support
unusual donor−acceptor transition metal → Bi bonding.62−65
Our previous study of the tris(2-pyridyl) ligand [Bi(6-Me-2-
py)3] (1) also shows that it can exhibit amphiphilic character
(being capable of coordinating anions and cations simulta-
neously), as revealed in particular by the unusual structure of
the Cu(I) dimer [Bi(6-Me-2-py)3(CuCl)]2 in which the
separate monomer units associate by Bi···Cl interactions.25
With this background in mind, we present here a study that
allows access to a range of tris(2-pyridyl) bismuthines
containing different functionalities in the pyridyl rings. We
explore how the introduction of different substituents on the
pyridyl rings (Figure 1e) can be used to control the steric and
electronic properties of the bismuthine ligands and thus their
reactivity and coordination behavior toward cations and
anions.
a
Isolated as their lithium halide complexes.
solvent used in the initial lithiation step were found to be the
most critical influences on the yield, with 2−4 being isolated in
60−88% crystalline yields after workup from these reactions
(see the Experimental Section).
We also extended this methodology to other 2-pyridyl ligand
arrangements without 6-substitution (Scheme 1b). In the
absence of steric congestion in the proximity of the donor-N
atoms of the 2-pyridyl ring units, these new ligands are all
isolated as their lithium halide complexes, 5·LiCl, 6·LiX, and 7·
LiX, in which X is either Cl or Br, or a mixture of the two
(according to X-ray diffraction). To our surprise, although a
small amount of black precipitate (presumably Bi metal) is
formed in the case of the unsubstituted bismuthine ligand,
careful optimization of the reaction conditions allowed us to
obtain the unsubstituted ligand [Bi(2-py)3] (5), which had
previously eluded ourselves and others.25,66 In addition, the
first examples of 3- and 5-methyl substituted ligand frame-
works, [Bi(5-Me-2-py)3] (6) and [Bi(3-Me-2-py)3] (7), were
also obtained. The isolated crystalline yields of the halide
complexes of 5−7 after workup were in the range 49−74%
(see the Experimental Section)
RESULTS AND DISCUSSION
■
Our recent success in the synthesis of [Bi(6-Me-2-py)3] (1)25
motivated us in the initial part of this study to test whether a
similar synthetic approach could be used to access a range of
related bismuthine ligands. This would be the first step toward
fine-tuning their electronic and steric properties by the
introduction of substituents in the pyridyl rings. We previously
attributed the stability of 1 compared to that of the
The new compounds 2−4 and the lithium halide complexes
of 5−7 were characterized by a range of NMR spectroscopic
and analytical techniques prior to their structural character-
ization by single-crystal X-ray diffraction (see the SI). As
expected, the solid-state structures of 2, 3, and 4 all show
B
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
pyramidal Bi(III) centers (Figure 2). All the N-pyridyl atoms
and 6-substituents are oriented “upwards”, approximately
Ligands 2−4 and the complexes 5·LiCl, 6·LiX, and 7·LiX are
all thermally stable and can be stored indefinitely in solid form
under a N2 atmosphere. They are also remarkably stable
toward moisture. With the exception of 7, which slowly
decomposes in the presence of excess H2O to generate free 3-
Me-2-py-H, the remaining compounds are stable toward
moisture, and no hydrolysis was observed 2 days after the
addition of ca. 15 equiv of H2O in toluene-d8 or CDCl3, as
1
monitored by H NMR spectroscopy. In fact, decoordination
of LiX from ligands 5 and 6 can be accomplished by extraction
with toluene/H2O (Experimental Section). Nominally halide-
free ligands 5 and 6 were obtained in this manner, and in the
case of 6, its structure was confirmed by X-ray crystallography
(see the SI).
Figure 2. Molecular structures of 2 (left), 3 (center), and 4 (right),
showing displacement ellipsoids at 50% probability. H atoms and the
disorder of one of the CF3 groups in 3 are omitted for clarity. Selected
bond lengths (Å) and angles (deg): 2, Bi−Cpy 2.252(12); Cpy−Bi−
Cpy 93.7(4). 3, Bi−Cpy 2.257(7); Cpy−Bi−Cpy 93.2(2). 4, Bi−Cpy
2.26(1)−2.23(1); Cpy−Bi−Cpy 94.7(4)−92.3(4). Color key: C
(gray), Bi (purple), N (blue), Br (brown), F (yellow). See also
Table S1 in the SI.
The isolation of ligands 5, 6, and 7 as lithium halide
complexes reflects their higher affinity for Li+, in contrast to
the 6-pyridyl substituted ligands 1−4, in which the donor-N
atoms of the pyridyl groups are more sterically congested.
Upon the addition of increasing amounts of LiCl to CDCl3
solutions of free ligands 5 and 6, a shift in the pyridyl signals is
observed in their 1H NMR spectra indicative of LiCl
coordination. This shift is largest for H-6 (i.e., next to the
pyridyl nitrogen), which is deshielded by around 0.5 ppm (see
Figure 4). These changes are accompanied by the appearance
of a singlet at 6.2 ppm in their 7Li NMR spectra resulting from
coordination of LiCl to the ligand. In contrast, addition of LiCl
to solutions of 1−4 under the same conditions did not result in
coordination to LiCl, as evidenced by 1H and 7Li NMR
spectroscopy. This indicates that 6-substitution of the pyridyl
ring completely blocks the coordination of LiCl. This may be
due in part to the poorer donor ability of the pyridyl N atoms
in the bismuthine ligands 2 and 3 (as a result of the presence of
electron-withdrawing Br and CF3 groups), but it is also likely
to be steric in origin.
With the new ligands 1 and 2−7 in hand, we next explored
their coordination to a range of metals. Reactions of 1 with
equimolar amounts of AgOTf, AgBF4 or AgPF6 in MeCN give
the new complexes [Bi(6-Me-2-py)3Ag(MeCN)]OTf (8·OTf),
[Bi(6-Me-2-py)3Ag(MeCN)]BF4 (8·BF4), and [Bi(6-Me-2-
py)3Ag(MeCN)]PF6 (8·PF6) (Scheme 2). Similar reaction of
4 with AgBF4 in MeCN gives [Bi(6-Ph-2-py)3Ag(MeCN)]BF4
(9·BF4). In contrast to ligands 1 and 4, no coordination was
observed between bismuthine ligands 2 or 3 and AgX salts (X
= OTf, BF4, PF6). Bearing in mind that the van der Waals
radius of CH3 (2.23 Å) is intermediate between those of CF3
(2.74 Å) and Br (1.85 Å),69,71 the inability of ligands 2 and 3
to coordinate Ag+ most likely arises from the electron-
withdrawing nature of the substituents (i.e., reducing the
donor ability) rather than just steric hindrance of the
coordination site. This point is emphasized by the fact that
despite its sterically hindering groups, 4 readily forms the
Ag(I) complex [Bi(6-Ph-2-py)3Ag(MeCN)][BF4] (9·BF4)
with AgBF4. The lithium halide complexes 5·LiX, 6·LiX, and
7·LiX proved to be very poor sources of the ligands 5, 6, and 7
since the halide ions interfered significantly in the trans-
metalation reactions with Ag+ salts. For example, reactions with
AgOTf in acetonitrile resulted in halogen/OTf anion exchange
with the precipitation of AgCl and formation of LiOTf
complexes, as shown by multinuclear NMR studies and the
solid-state characterization of the LiOTf complex of 6 (see the
SI). The reaction between lithium-halide-free ligand 5 and
Ag(OTf) in acetonitrile resulted in the precipitation of a white
toward the bismuth lone pair. The presence of electron-
withdrawing groups in 2−4 has no significant effect on the
bridgehead C−Bi−C angles compared to those of 1 (range
93.2(2)−94.7(4)° in 2−4, cf. 95.0(3)° in 1). Previous studies
have indicated that such acute angles indicate p-character in
the C−Bi bonds and accordingly s-character in the metal lone
pair.67
The solid-state structures of the crystalline complexes 5·
LiCl, 6·LiX·CH2Cl2, and 7·LiX·CH2Cl2 are shown in Figure 3.
While the single-crystal analysis of 5·LiCl indicated that Cl−
was the only halide ion present, crystals of 6·LiX and 7·LiX
were observed with site-disordered mixtures of Cl− and Br−.
Similar LiX coordination and site disordering of Cl− and Br−
have been observed during the synthesis of a number of other
tris(2-pyridyl) ligands and result from the in situ generation of
LiBr by Cl/Br exchange from the byproduct nBuBr.9,24
Molecules of each of these complexes consist of LiX units
(X = Cl/Br) in which the Li+ cation is tris-coordinated by the
three N atoms of the pyridyl rings of the tris(2-pyridyl)
bismuthine ligands. The presence of Li+ in bulk samples of the
7
complexes was confirmed by solution Li NMR spectroscopy.
Bulk samples of pure LiCl coordination complexes can be
obtained by the reactions of the mixed halide complexes with
tetrabutyl ammonium chloride. Mixed halide composition can
also be avoided by employing BiBr3 as the bismuth source
instead of BiCl3. This allowed us to prepare 6·LiBr and 7·LiBr
without Cl− inclusion (see the Experimental Section and SI).
In 5·LiCl (Figure 3a) and 6·LiX (Figure 3b), in which the
Bi(III) centers of the tris(2-pyridyl) ligands are exposed, short
intermolecular Bi···X contacts67,68 clearly link the molecules
together into a 1-D polymeric arrangement. The coordination
geometry around Bi becomes effectively disphenoidal (see-
saw), with the intermolecular contact occupying an axial
position. Comparable interactions are seen in 7·LiX (Bi···Br =
3.833(2) Å), but they are considerably longer on account of
the steric hindrance caused by the 3-Me groups flanking the
Bi(III) center (Figure 3c). This shows that substitution at the
3-position of the pyridyl ring can be used to modulate anion
coordination to Bi(III) in a similar manner to the way in which
6-substitution can be employed to control cation coordination
of the tris(2-pyridyl) bismuthine N atoms (see later).
C
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
Figure 3. (a, left) Molecular structure of the monomeric unit of 5·LiCl; displacement ellipsoids at 50% probability. (a, right). View along the b axis
and formation of a zigzag type structure through Bi···Cl interactions between the monomeric units. (b, left) Molecular structure of 6·LiX;
displacement ellipsoids at 50% probability. Cl/Br disorder is present, with a partial occupancy of 0.6 for Cl and 0.4 for Br. H atoms and the Br
component of the disorder, as well as one molecule of CH2Cl2 present in the asymmetric unit, are omitted for clarity. See the SI for the structure of
the pure 6·LiBr coordination complex. (b, right) View of 6·LiX along the a axis and formation of a zigzag type structure through Bi···Cl interactions
of the monomeric units. The Br component of the disorder is omitted for clarity. Both the Bi···Cl contacts in 5·LiCl (3.455(2) Å) and the Bi···Br
contacts in 6·LiBr (3.525(8) Å) are well below the sum of the relevant van der Waals radii (ΣVDW (Bi−Cl) = 3.82, ΣVDW(Bi−Br) = 3.90 Å).69,70 (c,
left) Molecular structure of the monomeric unit of 7·LiX; displacement ellipsoids at 50% probability. Cl/Br disorder is present, with a partial
occupancy of 0.7 for Cl and 0.3 for Br. See the SI for the pure LiCl and LiBr coordination complexes. H atoms and the Br component of the
disorder, as well as one molecule of CH2Cl2 present in the asymmetric unit, are omitted for clarity. See the SI for the structures of 7·LiCl and 7·
LiBr. (c, right) Space-filling view of 7 down the Bi···Li axis with the Li−X unit omitted and the 3-methyl groups highlighted in red. (c, bottom)
Space-filling representation of two adjacent 7·LiX molecules. The Br component of the disorder is omitted for clarity, and the 3-methyl groups are
highlighted in red. Selected bond lengths (Å) and angles (deg) for 5·LiCl: Bi−Cpy 2.266(8)−2.289(10), N−N 3.13(1)−3.154(9); Cpy−Bi−Cpy
92.3(4)−93.4(3), Cl−Bi−C11py 170.4(2) for 6·LiCl0.6Br0.4: Bi−Cpy 2.287(8)−2.257(8), N−N 3.174(8)−3.110(8); Cpy−Bi−Cpy 92.6(3)−93.2(3),
for 7·LiCl0.7Br0.3: Bi−Cpy 2.281(6)−2.296(8), N−N 3.115(9)−3.077(9). Color key: C (gray), Bi (purple), N (blue), Li (pink), Cl (green). See also
Table S1 in the SI.
D
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
Varying degrees of cation−anion interactions are found in 8·
OTf, 8·BF4, and 8·PF6. In 8·OTf (Figure 5a), the Bi(III)
bridgehead is involved in an additional long-range interaction
with one O atom of a OTf− anion and with the N atom of an
MeCN ligand. The Bi−N (3.309(6) Å) and Bi−O (3.326(6)
Å) distances involved are longer than expected for donor−
acceptor or coordination bonds but significantly shorter than
the sum of their van der Waals radii (3.62 and 3.59 Å,
respectively). Moving to the less coordinating anions BF4− and
−
PF6 , the Bi(III)···anion interactions are no longer present (see
the SI). In 8·PF6·2CH3CN the Bi(III) bridgehead is
coordinated by two MeCN ligands only, and in 8·BF4 no
−
secondary interaction is found with BF4 (see the SI).
The use of the more sterically congested bismuthine ligand 4
results in the significantly distorted cation 9·BF4 (Figure 5b).
An indication of this is seen in the coordination of the
molecule of MeCN to the Ag center, which is tilted away from
the Bi···Ag···N axis (Bi−Ag−N angle 162.4(1)°), unlike in the
cations [8]+ in which the Bi···Ag···N fragment is almost linear
(Bi···Ag···N range 176.1(2)−175.3(2)°). No expansion of the
Cpy−Bi−Cpy angles is observed in the cation [9]+ (94.9(2)−
96.7(2), cf. 93.3(2)−100.4(2) for cations [8]+), and therefore
the coordination of the MeCN molecule to Ag+ must be
accomplished by distortion of the pyridyl coordination
environment. A large twist of 49.2° in one of the Py units
with respect to the Bi···Ag axis occurs, which in turn results in
the elongation of the coordinating N−Ag bonds (2.464(3) Å,
cf. N−Ag distances in the range 2.307(5)−2.380(4) Å for the
cations [8]+). Figure 5c shows the cations [8]+ and [9]+ along
their Ag-acetonitrile axes and illustrates the more sterically
constrained nature of the coordination environment around
the Ag(I) center in cation [9]+ as compared to cations [8]+.
Recently, there has been great interest in closed-shell metal−Bi
interactions.48,65,73−75 In this regard, seemingly short Bi···Ag
contacts are present in the cations [8]+ and [9]+ (range
3.6746(6)−3.7291(4), cf. 3.79 Å for ΣVDW). However, it is
likely that these interactions are weak at best in this case.
Further investigations of the coordination behavior of these
bismuthine ligands toward the other coinage metals, copper
and gold, illustrate the noninnocent nature of some of these
ligands, which are subject to either 2-pyridyl ligand transfer or
reductive elimination. While the silver complexes 8·X (X =
1
Figure 4. H NMR spectra of the successive addition of LiCl to a
solution of free ligand 6. LiCl coordination is evident from the
observed shifts of the signals. H-6 (i.e., next to the pyridyl nitrogen,
highlighted in red) exhibits the largest shift of around 0.5 ppm. The
spectrum for 1 equiv of LiCl is identical to that of 6·LiCl in CDCl3.
No further changes to the spectrum were observed when >1 equiv of
LiCl was added.
Scheme 2. Synthesis of the Silver Complexes 8·X and 9·BF4
solid, suggesting the formation of a silver complex. However,
this was highly insoluble and could not be characterized.
The room-temperature 1H NMR spectra of the Ag+
complexes 8 and 9 in acetonitrile-d3 both show the presence
of only one pyridyl environment. The pyridyl resonances are
shifted downfield with respect to those of the free ligands 1
and 4, indicating coordination to Ag. In the case of complex 8,
the presence of different anions (OTf−, BF4 , and PF6 ) does
−
−
1
not substantially affect the H chemical shifts of the pyridyl
resonances.
OTf−, BF4 , PF6 ) and 9·BF4 are stable in rigorously dried
CH3CN in an N2 atmosphere, the corresponding Cu(I)
complexes of ligands 1 and 4 were found to be less stable.
Prolonged storage of the 1:1 reaction between [Cu(MeCN)4]-
BF4 and bismuthine ligand 1 at room temperature in MeCN
led to a gradual color change from pale yellow to orange, with
the formation of a few red and yellow crystals and a black
precipitate. X-ray analysis shows that the red crystals are the
copper(I) complex [Cu(Me-bpy)2]BF4 (Me-bpy = 6,6′-
dimethyl-2,2′-bipyridyl),76 while the yellow crystals are the
unusual Bi(III)/Cu(I) complex [{Bi(6-Me-2-py)3Cu}Cu(Me-
bpy)](BF4)2 (10·(BF4)2). The [{Bi(6-Me-2-py)3Cu}Cu(Me-
bpy)]2+ dication [10]2+ (Figure 6) consists of a [Bi(6-Me-2-
py)3Cu] subunit in which the Cu(I) center is only coordinated
by two of the three 2-pyridyl N atoms, with the third pyridyl-N
atom coordinating the Cu(I) center of a [Cu(Me-bpy)]+ unit,
giving rise to two trigonal planar Cu(I) environments. No π-
arene-Cu(I) interactions are present in this arrangement.
The formation of a bipyridine molecule as a ligand in the
cation of 10 must result from reductive elimination,
presumably from the initially formed [Bi(6-Me-2-py)3Cu-
−
−
The solid-state structures of the crystalline complexes 8·
OTf·MeCN, 8·BF4, 8·PF6·2CH3CN, and 9·BF4 have ion-
separated arrangements consisting of [{Bi(6-Me-2-py)}-
AgCH3CN]+ or [{Bi(6-Ph-2-py)3}AgCH3CN]+ cations and
the corresponding anions. Their complex cations contain Ag+
centers that are coordinated by the three pyridyl-N atoms of
the ligands and by a molecule of MeCN (Figure 5). The
structural arrangement of these silver complexes is related to
that found previously for the ion-separated Cu(I) complexes
[{E(6-Me-2-py)3}Cu·CH3CN]+PF6 (E = As, Sb, Bi).25
−
However, it differs from that of the silver complex [Ag@
Ag4(2-py3P)4(OTf)4](OTf) cluster, in which the tris(2-
pyridyl) phosphine ligand [P(2-Py)3] coordinates Ag(I)
through the pyridines and the phosphorus lone pair.72 In the
bismuthine silver complexes 8·X (X = OTf−, BF4 , and PF6 )
and 9·BF4− the low energy of the 6s orbitals of the lone pairs of
the bismuthine ligands results in no coordination to the soft
Ag(I) centers. Instead, the greater Lewis acidity at the bismuth
bridgehead atoms can result in solvent···Bi and anion···Bi
interactions (as also observed in the LiX complexes of 5−7).
−
−
E
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
Figure 5. (a) Molecular structure of complex 8·OTf([Bi(6-Me-2-py)3Ag(MeCN)]OTf); displacement ellipsoids at 50% probability. (b) Molecular
structure of complex 9·BF4 [Bi(6-Ph-2-py)3Ag(MeCN)] [BF4]; displacement ellipsoids at 50% probability. H atoms are omitted for clarity. (c)
Space-filling views of the cations [Bi(6-Me-2-py)3Ag(MeCN)][8]+ (left) and [Bi(6-Ph-2-py)3Ag(MeCN)][9]+ (right) down the Ag···Bi vector.
Selected bond lengths (Å) and angles (deg) for 8·OTf: Bi−Cpy 2.274(5)−2.288(5), N−Ag 2.307(5)−2.380(4); Cpy−Bi−Cpy 93.3(2)−99.0(2),
O−Bi−C11py 168.7(2), NacetonitrileBi−C21py 168.6(2) for 9·BF4: Bi−Cpy 2.258(5)−2.273(4), N−Ag 2.337(3)−2.464(3); Cpy−Bi−Cpy 94.9(2)−
96.7(2), F−Bi−C21py 175.7(1). Color key: C (gray), Bi (purple), N (blue), Ag (light gray), F (yellow), B (pink), O (red).
Scheme 3. Reductive Elimination from the 2-Pyridyl
Ligands of 1 and 4 (X = Cl−, BF4 )
−
Figure 6. (left) Solid-state structure and (right) line drawing of
complex dication [10]2+. Displacement ellipsoids shown at 50%
probability; H atoms and two BF4 anions omitted for clarity.
1
turned red, and the H NMR spectrum showed the formation
−
of Ph-bpy within the first 10 min. After 24 h at room
Selected bond lengths (Å) and angles (deg): Bi−Cpy 2.259(6)−
temperature, the 1H NMR spectrum shows the almost
2.291(9), Cpy−Bi−Cpy 90.4(3)−91.7(3). Color key: C (gray), Bi
exclusive formation of Ph-bpy, together with unidentified
minor products and with the appearance of a black precipitate
(see later discussion). Similar observations were made in the
(purple), N (blue), Cu (orange).
(MeCN)]+ cation in the manner illustrated in Scheme 3. This
reaction between 1 and CuCl. In this case, however, the
formation of Me-bpy proceeded more slowly, and after 5 days
at room temperature ca. 80% conversion had occurred.
An intriguing observation in these reactions is the marked
effect of the anion on the rate of these coupling reactions. As
seen in our previous study of the coordination chemistry of
1
was proved by in situ H NMR spectroscopic investigation of
the 1:1 reactions of 1 and 4 with [CuINCMe]BF4 or CuICl in
acetonitrile-d3 under N2 at room temperature. Upon mixing
[Cu(MeCN)4]BF4 and the bismuthine ligands 1 or 4,
immediate formation of the complexes [Bi(6-Me-2-
py)3CuNCMe]BF4 and [Bi(6-Ph-2-py)3CuNCMe]BF4 was
observed (see the SI). After 7 and 5 days, respectively, very
small amounts of the corresponding bipyridines Me-bpy and
6,6′-diphenyl-2,2′-dipyridyl (Ph-bpy) were formed. Much
faster reaction occurs using CuCl instead of [Cu(MeCN)4]-
BF4. The reaction of 4 and CuCl (1:1) in MeCN immediately
[Bi(6-Me-2-py)3]with CuX (X = Cl−, PF6 )25 as well as in the
−
current study with Ag(I) and Li salts, the Bi(III) bridgehead
atom is sufficiently Lewis acidic to interact with anions. The
presence of the more strongly coordinating chloride ligand in
CuCl (as compared to weakly coordinating BF4) could
potentially trigger ligand coupling by the transfer of the
F
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
halogen to the Bi(III) center, forming more reactive hyper-
valent bismuthate species which facilitate the transfer of the 2-
pyridyl groups and reductive elimination to bipyridines.
The black precipitate formed in these reactions could be
Bi(0) and/or Cu(0). In this regard, Cu(II)-mediated coupling
of pyridyl anions to bipyridines is a well-established synthetic
protocol, and one plausible mechanism for the coupling of the
pyridyl groups in our study involves the disproportionation of
Cu(I) into Cu(0) and Cu(II), with subsequent Cu(II)-
mediated coupling.77,78 To explore this possibility further,
CuCl2 was reacted with ligand 1 (1:1 equiv) in acetonitrile at
room temperature. The solution immediately turned red, and
orange crystals of the product [CuI(MeCN)(μ-Cl)(6-Me-2-
Py)2BiIIICl)] (11a) were obtained in 40% yield. The reaction
of ligand 3 with CuCl2 under the same conditions gave the
closely related complex [CuI(MeCN)(μ-Cl)(6-CF3-2-
Py)2BiIIICl)]·MeCN (11b·MeCN), although in this case
three equivalents of CuCl2 were required and unreacted ligand
3 was still present in the reaction mixture. The analogous
complex [CuI(MeCN)(μ-Cl)(6-Me-2-Py)2BiIIIBr)]·CH2Cl2
(11c·CH2Cl2) was obtained from the reaction of ligand 2
with CuBr2 in 24% crystalline yield. In situ 1H NMR
spectroscopy confirmed the formation of the corresponding
bipyridine products in each of the reactions producing 11a−
11c (Scheme 4). Compounds 11a−11c are stable in MeCN
Figure 7. (a) Solid-state structure of complex 11a. Compounds 11b
and 11c are isostructural (see the SI). Displacement ellipsoids shown
at 50% probability; H atoms and one molecule of MeCN are omitted
for clarity. (b) Association of molecules of 11a in the lattice (the
right-handed helix present in P41 is shown; for details of the helical
arrangement with the opposite handedness, see the SI). Selected bond
lengths (Å) and angles (deg): Bi−Cpy 2.30(1)−2.28(1), N−Cu
2.03(1)−2.05(1); Cpy−Bi−Cpy 92.1(4), Cl−Bi−Cl 169.19(13), Cl−
Bi−Cpy 165.9(3). Color key: C (gray), Bi (purple), N (blue), Cu
(orange), Cl (green).
Scheme 4. Formation of 11a, 11b, and 11c
Cu−(μ-X)−Bi bridges, these bonds being similar to those seen
previously in the few known examples of structurally
characterized [X2BiR2]− anions, e.g., Bi−Cl 2.688(3) and
2.773(3) Å in 11a, cf. 2.674(2) Å and 2.800(2) Å in
[Cl2BiAr2]− (Ar = 2-methylphenyl).80 Overall, two important
points are illustrated by the formation and structures of 11a−
11c: the coupling reaction of the 2-pyridyl groups is likely (at
least in part) to involve Cu(II) (via disproportionation of
2Cu(I) → Cu(0) + Cu(II)), and that pyridyl-bismuthine
ligands of this type can indeed function as fully fledged
amphiphilic ligands.
In the crystal lattices of the solvates 11b·CH3CNand 11c·
CH2Cl2 (which crystallize in the nonchiral space groups P21/c
and P-1, respectively), the monomer units are linked via Bi···Cl
or Bi···Br interactions. Molecules of 11b associate into
zigzagged polymers via Bi···Cl interactions (3.458 Å, cf.
ΣVDW = 3.82 Å), while in 11c this association only occurs to
form very loosely linked dimers in which the Bi···Br distance is
at the very limit of the van der Waals distance [(Bi···Br 3.872,
cf. 3.9 Å for ΣVDW(Br−Bi)] (see the SI). The Bi atoms of 11b·
CH3CN are also involved in long-range Bi···N interactions
with the lattice CH3CN molecules.
In contrast, 11a·CH3CN, which, like 11b and 11c, is an
achiral complex, crystallizes in the tetragonal chiral space group
P41 (Figure 7a) in which the molecules associate via Bi···Cl
interactions into chiral helical polymers formed by four
molecules of 11a around crystallographic 41 screw axes. This
leads to the formation of a right-handed helix (anticlockwise
looking down the crystallographic c axis). Whereas only the
terminal Cl atom is involved in the Bi···Cl interactions in 11b,
both the terminal and μ-Cl atoms are involved in the
intermolecular interactions in 11a (Bi···Cl mean 3.589 Å).
Further analysis of samples of 11a allowed us to obtain the
crystal structure of the other enantiomorph, which crystallizes
in space group P43 in crystals containing solely the left-handed
solution even in the presence of aerial oxygen for several days,
after which slow formation of the free pyridines was observed
by H NMR spectroscopy. Significantly, no formation of the
1
bipyridines was observed, proving that the coupling reaction
does not result from the effect of adventitious oxygen or
moisture on 11a−11c (i.e., they are not intermediates in the
coupling reaction). Although organobismuth compounds can
mediate different carbon−carbon bond forming reactions,
bismuthine ligand 1 is thermally stable, and no decomposition
or coupling reaction to produce Me-bpy was observed after
heating a sample of 1 in acetonitrile at 80 C for 24 h.79
Complexes 11a−11c are isostructural, having a Bi(III)/
Cu(I) arrangement which consists of an ion-pair between
hypervalent [X2Bi(2-R-py)2]− (X = Cl, Br) anions and the
Cu(MeCN)+ cation, nicely illustrating the ability of the newly-
formed pyridine bismuthine ligands to simultaneously
coordinate anions and cations. Figure 7a shows the structure
of 11a. As expected, the Bi(III) centers within these anions
adopt similar distorted trigonal-bipyramidal geometries with
the Bi lone pair formally occupying an equatorial position and
the (most electronegative) halogen ligands axial (consistent
with VSEPR theory). The Cu(I) centers are coordinated by
the two pyridyl-N atoms of the [X2Bi(2-R-py)2]− anions and
by one of the halogen atoms. Support for the conclusion that
these complexes contain hypervalent [X2Bi(2-R-py)2]− anions
is seen in a comparison in the Bi−X bond lengths within the
G
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
helix (see the SI). Compound 11a is an example of crystalline
enantiomorphism emerging from an achiral complex.81,82
A related structural arrangement to 11a−11c is formed in
the 1:1 reaction of 1 with FeCl2 to give the heterometallic
Bi(III)/Fe(II) complex [ClBi(6-Me-2-Py)2FeCl2] (12) (Fig-
ure 8a). This reaction results in significant decomposition and
position is formally occupied by the lone pair). Compound 12
forms a 1-D zigzagged polymer in the crystal lattice via Bi···Cl
interactions between the monomer units (see the SI).
Metal−halogen transfer is also observed in the reaction of
FeI2 with 1, from which a few crystals of Bi[(6-Me-2-py)2HI2]
(13) were isolated and structurally characterized by X-ray
crystallography. Like 12, 13 contains a hypervalent Bi(III)
center (Figure 8b) and can be regarded as an advanced state of
the situation seen in the structure of 12, in which full transfer
of the halogen (iodine) from the Fe(II) to the Bi(III) center
has occurred. This leads to the formation of an anionic
bismuthate complex [I2Bi(6-Me-2-Py)2]−, which is then
protonated at one of the pyridyl-N atoms in the reaction
medium to give 13 (with the resulting formation of a relatively
strong N−H···N hydrogen bond between the two pyridyl
groups). Dimerization of these units occurs in the solid state
via intermolecular Bi−I···Bi interactions (3.7988(6) Å, cf. 4.05
Å for the sum of their VdW radii) (Figure 8c).
The ability for tris(2-pyridyl) ligands to act as pyridyl
transfer reagents has been seen previously in the case of the
highly reactive and moisture-sensitive [MeAl(2-py)3]−
anion33,61 and is symptomatic of low bond energy of the C-
bridgehead bonds in ligands containing more electropositive
(metallic) bridgehead atoms. The ability for 1 to act in a
similar way is seen in the example of its reaction with Au(I)
salts. While the reaction of 1 and ClAu(tht) (tht =
tetrahydrothiophene) in THF led to the formation of an
intractable yellow precipitate that could not be further
investigated due to its marked insolubility, reaction of
(OTf)AuPPh3 with 1 in acetone resulted in a mixture of
compounds as shown by 1H NMR, including the appearance of
an unexpected broad resonance at δ = ca. 12 ppm. After storing
the reaction mixture for 48 h at −25 °C, a few crystals of the
new compound [{(6Me-2-Py)Au(PPh3)}2H][OTf] (14·OTf)
were formed. Despite difficulties in its collection and
refinement (due to modeling of disordered triflate; see SI),
the single-crystal X-ray data of 14·OTf define its structure
unambiguously. The solid-state structure shows that 14·OTf
has an ion-separated arrangement containing the cation [{(6-
Me-2-Py)Au(PPh3)}2H]+ (14) (Figure 8d) and OTf− anions.
The cation consists of a (pyridyl)Au−Au(pyridyl) bonded
dimer arrangement in which one of the pyridyl-N atoms is
protonated, resulting in an overall positive charge and the
formation of a relatively strong N−H···N hydrogen bond
(similar to 13). The pyridyl transfer from bismuthine 1 to
Au(I) is consistent with previous observations by Schmidbaur,
in which the coordination of tertiary bismuthanes (R3Bi:) to
Au(I) was prevented by rapid transmetalation, leading to the
formation of organogold compounds.85
Figure 8. (a) Molecular structure of [ClBi(6-Me-2-Py)2FeCl2] (12).
H atoms have been omitted for clarity. Thermal ellipsoids at 50%
probability. (b) Solid-state structure of 13 and (c) its association into
dimers through Bi−I intermolecular interactions. Displacement
ellipsoids shown at 50% probability. H atoms (except H1) are
omitted for clarity. (d) Solid-state structure of the gold pyridyl cation
[{(6Me-2-Py)Au(PPh3)}2H] [14]+. H atoms (except H1) and the
OTf anion are omitted for clarity. Displacement ellipsoids shown at
50% probability. Selected bond lengths (Å) and angles (deg): 12, Bi−
Cpy 2.298(8)−2.287(7), N−Fe 2.144(6)−2.151(6); Cpy−Bi−Cpy
92.1(2), Cl−Bi−Cl 170.13(6), Cl−Bi−C1py 164.18(6). 13, Bi−Cpy
2.286(6), 2.281(7), Cpy−Bi−Cpy 94.3(2), I−Bi−C11py170.5(2).
Owing to difficulties with the structure refinement, no bond lengths
or angles are quoted for compound 14·OTf. Color key: C (gray), Bi
(purple), N (blue), Au (yellow, P (light orange), Fe (dark orange), O
(dark red), Cl (green), I (red).
the formation of a black precipitate, presumably of Bi and/or
Fe metal or even Bi−Fe intermetallic compounds. The
observation of the formation of black precipitates throughout
these studies could be due to the formation of Bi−transition
metal intermetallics, which could echo recent findings by Vela
in the synthesis of 10−14, 10−15, and 11−15 binary
intermetallics from heterobimetallic single-source precur-
sors.83,84 The low isolated yield of 12 meant that it was only
characterized by X-ray crystallography. The formation of 12
presumably results from metal−halogen transfer from Fe(II) to
Bi(III). However, because of the paramagnetic nature of the
reaction solution, we were not able to determine the presence
of Me-bpy in solution, and it is therefore unknown whether
any pyridyl coupling occurs in this case. In the structure of 12,
the FeII and BiIII atoms are bridged by 6-Me-2-py groups and
by a μ-Cl atom, with both Bi(III) and Fe(II) having trigonal
bipyramidal geometries (in the case of Bi(III), the fifth
CONCLUSIONS
■
The particular interest in tris-pyridyl bismuthine ligands of the
type [Bi(2-py′)3] is their ability to behave as amphiphilic
ligands that are capable of coordinating anions at the Lewis
acid Bi(III) bridgehead and at the same time coordinating
cations at the donor-N atoms. Our study has provided a range
of bismuthine ligands of this type beyond the single example
previously reported, illustrating that a range of electron-
donating and -withdrawing groups can be introduced into the
pyridyl frameworks at various positions. Importantly, we find
that 6-Me substitution is not essential for the stabilization of
these ligands and that even the unsubstituted ligand 5 is
thermally stable. The nature of the substituents (electron-
H
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
solution using perfluorohydrocarbon oil to prevent atmospheric
oxidation, hydrolysis, and solvent loss. Data integration, scaling, and
empirical absorption correction were performed using the CrysAlisPro
software package. The structure was solved by direct methods and
refined by full-matrix-least-squares against F2 with SHELX in OLEX2.
Non-hydrogen atoms were refined anisotropically, and hydrogen
atoms were placed at idealized positions and refined using the riding
model. Graphics were made with OLEX2 and MERCURY. In the case
of 11, data was collected on a Bruker D8 QUEST diffractometer with
an Incoatec IμS Cu microfocus source.
donating or -withdrawing and the steric effects) has a
significant impact on the ligand properties. For example, the
introduction of 6-Br and 6-CF3 groups in the ligands 2 and 3
severely curtails the donor ability. Conversely, substitution at
the 3-position in the ligand 6 sterically shields the Bi(III)
center and reduces its ability to coordinate anions. These
features allow control of the coordination ability of the ligand
regarding both cation and anion coordination.
The weakness of the C−Bi bonds in these ligands is
expressed in their reactions with Cu(I/II), Fe(II), and Au(I).
In the case of Cu(I), coupling of the pyridyl groups to the
corresponding bipyridines is observed, the rate of which is
dependent on the anion present in the Cu(I) salt used. This
reaction most probably involves disproportionation of Cu(I) to
Cu(II) and Cu(0), as illustrated by the reactions of 6-
substituted 1 and 3 with CuIIX2 (X = halide) which results in
both pyridyl coupling and the formation of Cu(I) complexes
containing hypervalent Bi(III) [X2Bi(2-R-py)]− species. A
related characteristic is the ability of the bismuthine frame-
works to exchange ligands, undergoing metal−halogen or
pyridyl transfer with Fe(II) and Au(I) salts.
CCDC 1981115−1981137 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of charge
from The Cambridge Crystallographic Data Center.
n
Synthesis of 2. BuLi (8 mL, 20 mmol, 2.5 M in hexane) was
dissolved in THF (40 mL). 6-Dibromopyridine (4.74 g, 20 mmol) in
THF (28 mL) was added dropwise over 30 min at −78 °C. The
resulting dark green solution was stirred for 70 min at −78 °C. A
suspension of BiCl3 (2.1 g, 6.66 mmol) in THF (6 mL) was added
dropwise to the lithiated species, and the resulting light green mixture
was stirred for 2 h. Subsequently, the resulting white mixture was
allowed to reach room temperature. After overnight stirring, all
volatiles were removed under vacuum, and the resulting white solid
residue was extracted with warm toluene (40 mL). The suspension
was filtered through Celite to yield a pale-yellow solution, which was
concentrated under vacuum until the precipitation of a white solid
was observed, which was redissolved by gentle heating. Storage
overnight at −24 °C yielded 2 as white blocks suitable for X-ray
Overall, this study provides a range of tris(2-pyridyl)
bismuthines and reveals their interesting coordination and
reaction characteristics (as well as their limitations) as ligands.
We are continuing our studies in this area, particularly with
respect to the use of p-block tris(2-pyridyl) species as reagents
for chiral discrimination, in supramolecular chemistry and
catalysis.
1
crystallography. Yield 2.94 g (4.34 mmol, 65%). H NMR (298 K,
toluene-d8, 500 MHz): δ = 7.60 (d, J = 6.9 Hz, 3H, H3 py), 6.78−6.72
(m, 6H, H4+H5 py). 13C{1H} NMR (298 K, toluene-d8, 100.6 MHz):
δ = 196.2 (br, C2 py), 132.2 (C3 py), 145.7 (C6 py), 138.1 (C4 py),
126.1 (C5 py). These resonances were observed and unambiguously
1
1
assigned through H−13C HMBC and H−13C HMQC experiments.
HR-MS [ESI, positive ion mode ESI-TOF]: m/z for C15H9BiBr3N3
[2+H]+ calcd: 679.8203. Found: 679.8238 (−5.06 ppm error).
Synthesis of 3. 2-Bromo-6-(trifluoromethyl)pyridine (4.520 g, 20
mmol) was dissolved in diethyl ether (40 mL). To this was added
EXPERIMENTAL SECTION
■
General Experimental Techniques. All syntheses were carried
out on a vacuum line under a N2 atmosphere. Products were isolated
and handled under a N2 atmosphere. Liquid pyridines, NMR solvents,
and reaction solvents were stored over molecular sieves and degassed
by three freeze−pump−thaw cycles under N2 prior to use. [Bi(6-Me-
2-py)3] (1) was synthesized as described previously. NMR spectra
were recorded on 500 MHz Agilent DD2 instruments equipped with a
cold probe and a 400 MHz Agilent instrument equipped with a
ONEPROBE in the Laboratory of Instrumental Techniques (LTI)
Research Facilities, University of Valladolid. Chemical shifts (δ) are
reported in parts per million (ppm). 1H and 13C NMR are referenced
to TMS. 7Li and 19F NMR experiments are referenced to a solution of
LiCl/D2O and CCl3F, respectively. Coupling constants (J) are
reported in Hz. Standard abbreviations are used to indicate
multiplicity: s = singlet, d = doublet, t = triplet, and m = multiplet.
1H and 13C peak assignments were performed with the help of
n
dropwise BuLi (8 mL, 20 mmol, 2.5 M in hexane) over 30 min at
−78 °C. The resulting orange solution was stirred for 3 h at −78 °C.
A suspension of BiCl3 (2.1 g, 6.66 mmol) in THF (6 mL) was added
dropwise to the dark orange lithiated species, and the resulting pale
brown mixture was allowed to reach room temperature. After
overnight stirring, a dark brown solution with a brown precipitate
was observed. All volatiles were removed under vacuum, and the
resulting solid residue was extracted with warm toluene (40 mL). The
suspension was filtered through Celite to yield a brown solution,
which was concentrated under vacuum until the precipitation of a
white solid was observed, which was redissolved by gentle heating.
Storage overnight at −24 °C yielded 3 as white blocks suitable for X-
ray crystallography. Yield 3.80 g (5.87 mmol, 88%). 1H NMR (298 K,
toluene-d8, 400 MHz): δ (ppm) = 7.95 (d, J = 7.75 Hz, 3H, H3 py),
7.03 (t, J = 7.75 Hz, 3H, H4 py), 6.94 (d, J = 7.75 Hz, 3H, H5 py).
13C{1H} NMR (298 K, toluene-d8, 100.5 MHz): δ = 195.7 (br, C2
py), 150.8 (q, JC−F = 34 Hz, C6 py), 136.5 (C4 py), 135.5 (C3 py),
122.2 (q, JC−F = 272 Hz, C7 py), 118.5 (q, JC−F = 3 Hz, C5 py). 19F
NMR (298 K, toluene-d8, 376 MHz): δ = −62.62 (s, 9F, CF3).
Elemental analysis (%) calcd for 3 (C18H9BiF9N3): C 33.4, H 1.4, N
6.5. Found: C 33.2, H 1.6, N 6.4. HR-MS [ESI, positive ion mode
ESI-TOF]: m/z for C18H9BiF9N3 [3+H]+ calcd: 648.0529. Found:
648.0532 (−0.35 ppm error).
Synthesis of 4. 2-Bromo-6-(phenyl)pyridine (1.170 g, 5 mmol)
was dissolved in THF (20 mL). To this was added dropwise nBuLi (2
mL, 5 mmol, 2.5 M in hexane) over 30 min at −78 °C. The resulting
red solution was stirred for 1 h at −78 °C. A suspension of BiCl3
(0.525 g, 1.66 mmol) in THF (5 mL) was added dropwise to the dark
red lithiated species, and the resulting pale red mixture was allowed to
reach room temperature. After overnight stirring, a clear red solution
was observed. All volatiles were removed under vacuum, and the
resulting solid residue was extracted with warm toluene (15 mL). The
suspension was filtered through Celite to yield a red solution, which
1
additional 2D NMR experiments (1H−1H COSY, H−1H NOESY,
1
1H−13C HSQC, and H−13C HMBC). High-resolution mass spectra
were recorded at the mass spectrometry service of the Laboratory of
Instrumental Techniques (LTI) of the University of Valladolid and
́
the Centros de Apoyo a la Investigacion (CAI) of the University of
́
Alcala. A MALDI-TOF system (MALDI-TOF) and a Bruker autoflex
speed (N2 laser: 337 nm, pulse energy: 100 μJ, 1 ns; acceleration
voltage: 19 kV, reflector positive mode) were used. trans-2-[3-(4-tert-
Butylphenyl)-2-methyl-2-propenylidene]malonitrile (DCTB) was
used as the matrix. Elemental analysis was obtained using a CHNS-
́
932 Elemental Analyzer at the CAI of the University of Alcala. In
cases where we have been unable to obtain satisfactory elemental
analysis, the formulations of the compounds are either supported by
X-ray structure determination or high-resolution mass spectroscopy
(in addition to NMR spectroscopy).
X-ray Diffraction Studies. Diffraction data were collected using
an Oxford Diffraction Supernova diffractometer equipped with an
Atlas CCD area detector and a four-circle kappa goniometer. For the
data collection, Mo or Cu microfocused sources with multilayer optics
were used. When necessary, crystals were mounted directly from
I
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
was concentrated under vacuum until the precipitation of a white
solid was observed, which was redissolved by gentle heating. Storage
overnight at −24 °C yielded 4 as white needles suitable for X-ray
was hampered by salt metathesis resulting in LiX (where X is a
mixture of Cl and Br, leading to X = Cl0.6Br0.4 as determined from
single crystal X-ray crystallography). This problem was avoided in the
preparation of the analogous 6·LiBr described above. Yield (calculated
as 6·LiCl0.6Br0.4·CH2Cl2): 2.4 g (3.80 mmol, 57.05%). 1H NMR (298
K, DMSO-d6, 500 MHz): δ = 8.45 (s, 3H, H6 py), 7.58 (s, 6H, H3+H4
py), 2.23 (s, 3H, H7 Me). 13C{1H} NMR (298 K, DMSO-d6, 100.6
MHz): δ = 189.57 (C2 py), 152.78 (C6 py), 137.36 (C4 py), 133.80
1
crystallography. Yield 0.663 g (0.99 mmol, 60%). H NMR (298 K,
toluene-d8, 500 MHz): δ = 8.09 (d, J = 7.8 Hz, 6H, H8 Ph), 7.82 (d, J
= 7.6 Hz, 3H, H3 py), 7.27−7.22 (m, 9H, H5+H9 py+Ph), 7.21−7.16
(m, 6H, H4+H10 py+Ph). 13C{1H} NMR (298 K, toluene-d8, 100.6
MHz): δ = 195.42 (C2 py), 159.66 (C6 py), 139.82 (C7Ph),137.08
(C4 py), 133.14 (C3 py), 128.97 (C10Ph), 128.78 (C5 py), 127.26
(C8Ph), 118.45 (C9Ph). Elemental analysis (%) calcd for 4
(C33H24BiN3): C 59.0, H 3.6, N 6.3. Found: C 59.1, H 3.7, N 6.4.
HR-MS [ESI, positive ion mode ESI-TOF]: m/z for C18H9BiF9N3
[4+H]+ calcd: 672.1847. Found: 672.1856 (−1.41 ppm error).
Synthesis of 5·LiCl·CH2Cl2. 2-Bromopyridine (1.90 mL, 20
mmol) was dissolved in THF (40 mL). To this was added dropwise
nBuLi (8 mL, 20 mmol, 2.5 M in hexane) over 30 min at −78 °C. The
resulting green suspension was stirred for 2.5 h at −78 °C. A
suspension of BiCl3 (2.1 g, 6.66 mmol) in THF (6 mL) was added
dropwise to lithiated species, and the resulting gray mixture was
allowed to reach room temperature. After overnight stirring, a gray
solution with a white precipitate was observed. All volatiles were
removed under vacuum, and the resulting solid residue was extracted
with DCM (40 mL). The suspension was filtered through Celite to
yield a red solution, which was concentrated under vacuum, and slow
diffusion of n-hexane (20 mL) at −24 °C yielded 5·LiCl·CH2Cl2 as
white needles suitable for X-ray crystallography. Yield (calculated as 5·
7
(C3 py), 131.35 (C5 py), 18.01 (C7 Me). Li NMR (298 K, DMSO-
d6, 194.2 MHz): δ = −1.02. 7Li NMR (298 K, CDCl3, 194.2 MHz): δ
= 6.21. HR-MS [Maldi, positive ion mode Maldi-TOF]: m/z for
C18H18BiN3 [6+H]+ calcd: 486.1377. Found: 486.1388 (1.1 ppm
error).
Synthesis of 6·OTf. 6·LiX (X = Cl or Br, 0.294 mmol) was
dissolved in DCM (10 mL). To this was added AgOTf (75.5 mg,
0.294 mmol). The resulting white suspension was stirred for 1 h at rt.
The suspension was filtered through Celite to yield a colorless
solution which was concentrated under vacuum, and slow diffusion of
n-hexane (5 mL) at −24 °C yielded 6·OTf as white needles suitable
1
for X-ray crystallography. Yield 48 mg (0.082 mmol, 41%). H NMR
(298 K, CDCl3, 500 MHz): δ = 8.83 (d, J = 2.0 Hz, 3H, H6 py), 7.72
(d, J = 7.70 Hz, 3H, H3), 7.51 (dd, J = 2.0/7.70 Hz, 3H, H4), 2.26 (s,
9H, H7 Me). 13C{1H} NMR (298 K, CDCl3, 100.6 MHz): δ = 181.4
(C2 py), 154.7 (C6 py), 137.8 (C4 py), 134.7 (C3 py), 134.1 (C5 py),
7
18.7 (C7 Me). Li NMR (298 K, CDCl3, 194.2 MHz): δ = 5.35. 19F
NMR (298 K, MeCN-d3, 376 MHz): δ = −78.02 (s, 3F, OTf−).
Synthesis of 7·LiBr·0.5CH2Cl2. 2-Bromo-3-(methyl)pyridine
(1.11 mL, 10 mmol) was dissolved in THF (20 mL). To this was
added dropwise nBuLi (4 mL, 10 mmol, 2.5 M in hexane) (30 min) at
−78 °C. The resulting dark red solution was stirred for 2 h at −78 °C.
A solution of BiBr3 (1.49 g, 3.33 mmol) in THF (5 mL) was added
dropwise to the dark red lithiated species. The resulting brown
mixture was allowed to reach room temperature. After overnight
stirring, a colorless solution with a white precipitate was observed. All
volatiles were removed under vacuum, and the resulting solid residue
was extracted with DCM (20 mL). The suspension was filtered
through Celite to yield a red solution, which was concentrated under
vacuum, and slow diffusion of n-hexane (20 mL) at −24 °C yielded 7·
LiBr CH2Cl2 as white crystals suitable for X-ray crystallography. Yield
(calculated as 7·LiBr·0.5CH2Cl2): 1.44 g (2.34 mmol, 75%). 1H NMR
(298 K, DMSO-d6, 500 MHz): δ = 8.29 (d, J = 4.65 Hz, 3H, H6 py),
7.66 (d, J = 7.5 Hz, 6H, H4 py), 7.20−7.23 (m, 3H, H5 py), 2.22 (s,
3H, H7 Me). 13C{1H} NMR (298 K, DMSO-d6, 100.6 MHz): δ =
195.92 (C2 py), 149.71 (C6 py), 142.89 (C3 py), 136.39 (C4 py),
1
LiCl·CH2Cl2): 2.35 g (4.11 mmol, 61%). H NMR (298 K, DMSO-
d6, 500 MHz): δ = 8.60 (m, 3H, H6 py), 7.80−7.72 (m, 6H, H4+H5
py), 7.29 (m, 3H, H3 py). 13C{1H} NMR (298 K, DMSO-d6, 100.6
MHz): δ = 194.53 (C2 py), 152.45 (C6 py), 136.75 (C4 py), 134.30
(C5 py), 122.29 (C3 py). 7Li NMR (298 K, DMSO-d6, 194.2 MHz): δ
= −1.07. 7Li NMR (298 K, CDCl3, 194.2 MHz): δ = 6.25. Elemental
analysis (%) calcd for 5·LiCl·CH2Cl2(C16H14BiCl3LiN3): C 33.7, H
2.5, N 7.4. Found: C 34.0, H 2.7, N 8.2. HR-MS [ESI, positive ion
mode ESI-TOF]: m/z for C15H12BiLiN3 [5+Li]+ calcd: 450.0990.
Found: 450.0981 (2.07 ppm error).
Synthesis of 6·LiBr·CH2Cl2. 2-Bromo-5-(methyl)pyridine (1.72 g,
10 mmol) was dissolved in THF (20 mL). To this was added
n
dropwise BuLi (4 mL, 10 mmol, 2.5 M in hexane) over 30 min at
−78 °C. The resulting red solution was stirred for 2.5 h at −78 °C. A
solution of BiBr3 (1.49 g, 3.33 mmol) in THF (5 mL) was added
dropwise to the dark red lithiated species. The resulting pale brown
mixture was allowed to reach room temperature. After overnight
stirring, a brown solution with a white precipitate was observed. All
volatiles were removed under vacuum, and the resulting solid residue
was extracted with DCM (20 mL). The suspension was filtered
through Celite to yield a brown solution, which was concentrated
under vacuum, and slow diffusion of n-hexane (20 mL) at −24 °C
yielded 6·LiBr·CH2Cl2 as white needles suitable for X-ray
crystallography. Yield (calculated as 6·LiBr·CH2Cl2): 1.59 g (2.42
7
121.99 (C5 py), 22.56 (C7 Me). Li NMR (298 K, DMSO-d6, 194.2
MHz): δ = −1.15. Elemental analysis (%) Calcd for 7·LiBr·
0.5CH2Cl2(C18.5H19BiBrClLiN3): C 36.2, H 3.1, N 6.8. Found C
36.5, H 3.3, N 7.3.
Synthesis of 7·LiX. 2-Bromo-3-(methyl)pyridine (2.22 mL, 20
mmol) was dissolved in THF (30 mL). To this was added dropwise
nBuLi (8 mL, 20 mmol, 2.5 M in hexane) over 30 min at −78 °C. The
resulting dark red solution was stirred for 2 h at −78 °C. A suspension
of BiCl3 (2.1 g, 6.66 mmol) in THF (6 mL) was added dropwise to
the dark red lithiated species. The resulting brown mixture was
allowed to reach room temperature. After overnight stirring, a
colorless solution with a white precipitate was observed. All volatiles
were removed under vacuum, and the resulting solid residue was
extracted with DCM (40 mL). The suspension was filtered through
Celite to yield a red solution, which was concentrated under vacuum,
and slow diffusion of n-hexane (20 mL) at −24 °C yielded 7·
LiCl0.7Br0.3·CH2Cl2 as white needles suitable for X-ray crystallography.
When the samples were left under persistent vacuum, an amorphous
material that was found to contain no CH2Cl2 solvation was obtained,
corresponding to 7·LiCl0.7Br0.3. Yield (calculated as 7·LiCl0.7Br0.3):
1.78 g (3.28 mmol, 49.2%). 1H NMR (298 K, DMSO-d6, 500 MHz):
δ = 8.29 (d, J = 4.65 Hz, 3H, H6 py), 7.66 (d, J = 7.5 Hz, 6H, H4 py),
7.20−7.23 (m, 3H, H5 py), 2.22 (s, 3H, H7 Me). 13C{1H} NMR (298
K, DMSO-d6, 100.6 MHz): δ = 195.92(C2 py), 149.71 (C6 py),
1
mmol, 73%). H NMR (298 K, DMSO-d6, 500 MHz): δ = 8.45 (s,
3H, H6 py), 7.58 (s, 6H, H3+H4 py), 2.23 (s, 3H, H7 Me). 13C{1H}
NMR (298 K, DMSO-d6, 100.6 MHz): δ = 189.57 (C2 py), 152.78
(C6 py), 137.36 (C4 py), 133.80 (C3 py), 131.35 (C5 py), 18.01 (C7
Me). 7Li NMR (298 K, DMSO-d6, 194.2 MHz): δ = −1.16. Elemental
analysis (%) calcd for 6·LiBr·CH2Cl2 (C19H20BiBrCl2LiN3): 34.7, H
3.1, N 6.4. Found: C 34.0, H 3.2, N 6.5.
Synthesis of 6·LiCl. 2-Bromo-5-(methyl)pyridine (3.44 g, 20
mmol) was dissolved in THF (40 mL). To this was added dropwise
nBuLi (8 mL, 20 mmol, 2.5 M in hexane) over 30 min at −78 °C. The
resulting red solution was stirred for 2.5 h at −78 °C. A suspension of
BiCl3 (2.1 g, 6.66 mmol) in THF (6 mL) was added dropwise to the
dark red lithiated species. The resulting pale brown mixture was
allowed to reach room temperature. After stirring overnight, a brown
solution with a white precipitate was observed. All volatiles were
removed under vacuum, and the resulting solid residue was extracted
with DCM (40 mL). The suspension was filtered through Celite to
yield a red solution, which was concentrated under vacuum, and slow
diffusion of n-hexane (20 mL) at −24 °C yielded 6·LiX·CH2Cl2 as
white needles suitable for X-ray crystallography. Elemental analysis
7
142.89 (C3 py), 136.39 (C4 py), 121.99 (C5 py), 22.56 (C7 Me). Li
NMR (298 K, DMSO-d6, 194.2 MHz): δ = −0.91. 7Li NMR (298 K,
J
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
CDCl3, 194.2 MHz): δ = 6.73. HR-MS [Maldi, positive ion mode
Maldi-TOF]: m/z for C18H18BiLiN3 [7+Li]+ calcd: 492.1460. Found:
492.1485 (2.5 ppm error). HR-MS [Maldi, positive ion mode Maldi-
TOF]: m/z for C18H18BiN3 [7+H]+ calcd: 486.1377. Found:
486.1405 (2.8 ppm error). We found that when samples were left
to crystallize for long periods, salt metathesis can occur, leading to the
formation of crystals of 7LiX (X = Cl, Br) containing variable
amounts of LiBr. When this happens, bulk samples of pure 7·LiCl can
be obtained by treatment with an excess of tetrabutyl ammonium
chloride (TBACl) as follows. Typically, 100 mg of LiX and TBACl
(415 mg, 3.79 mmol) was dissolved in DCM (4 mL). After overnight
stirring, the colorless solution was concentrated under vacuum, and
slow diffusion of n-hexane (3 mL) at −24 °C yielded 7·LiCl·CH2Cl2
as colorless crystals suitable for X-ray crystallography. Yield
(calculated as 7·LiCl·CH2Cl2): 62.8 mg (0.11 mmol, 58%). Elemental
analysis (%) Calcd for 7·LiCl (C18H18BiClLiN3): C 41.0, H 3.4, N
8.00. Found: C 41.8, H 4.0, N 8.1.
Subsequently, the solvents were evaporated, and the residue was
redissolved in MeCN (5 mL). The colorless solution was
concentrated under vacuum until the precipitation of a white
precipitate was observed. Storage at −24 °C yielded 9·BF4 as
colorless crystals suitable for X-ray crystallography. The product was
isolated by filtration. Yield 45 mg (0.049 mmol, 66%). Similarly to 8·
X, the crystals of 9·BF4 were found to be very unstable toward light
and moisture, resulting in rapid loss of crystallinity and formation of a
black amorphous solid, which hampered elemental analysis. 1H NMR
(298 K, MeCN-d3, 500 MHz): δ = 8.00−7.96 (m, 6H, H3+H4 py),
7.71 (m, 3H, H5 py), 7.59 (d, J = 7.10 Hz, 6H, H8 Ph), 7.39 (t, J =
7.10 Hz, 6H, H10 Ph), 7.31 (t, J = 7.10 Hz, 6H, H9 Ph). 13C{1H}
NMR (298 K, MeCN-d3, 100.6 MHz): δ = 198.3 (br, C2 py), 163.19
(C6 py), 141.9 (C7 Ph), 139.3 (C4 py), 135.6 (C3 py), 130.2 (C10 Ph),
129.4 (C9 Ph), 128 (C8 Ph), 123.2 (C5 Ph). 19F NMR (298 K,
−
−
MeCN-d3, 376 MHz): δ = −151.97 (s, 10BF4 ), −152.03 (s, 11BF4 ).
HR-MS [Maldi, positive ion mode Maldi-TOF]: m/z for
C33H24AgBiN3 [9-CH3CN]+ calcd: 778.0820. Found: 778.0824 (0.4
ppm error).
Decoordination of LiX from Ligands 5 and 6. A suspension of
5·LiX or 6·LiX (0.20 mmol) in toluene (10 mL) was extracted with
water (3 × 2 mL). The extract was dried over anhydrous magnesium
sulfate and then filtered through Celite. The solvent was removed by
evaporation under reduced pressure to give a white oil, which yielded
crystalline samples of halide-free 5 and 6 as colorless needles
overnight at −24 °C. The absence of LiX in the samples was verified
by 7Li NMR spectroscopy. Compound 5. Yield: 65.7 mg (0.148
mmol, 72%). 1H NMR (298 K, CDCl3, 500 MHz): δ = 8.68 (m, 3H,
H6 py), 7.73 (m, 6H, H5 py), 7.65 (m, 3H, H4 py), 8.21 (m, 3H, H3
py). 13C{1H} NMR (298 K, CDCl3, 100.6 MHz): δ = 194.3 (C2 py),
152.9 (C6 py),137.2 (C4 py), 134.0 (C5 py), 122.3 (C3 py). HR-MS
[Maldi, positive ion mode Maldi-TOF]: m/z for C15H12BiN3 [M +
H]+ calcd: 444.0908. Found: 444.0919 (1.1 ppm error). Compound
Synthesis of 10. Bi(6-Me-2-py)3 (150 mg, 0.30 mmol) was
dissolved in MeCN (2 mL)/THF (2 mL). To this solution was added
[Cu(MeCN)4]BF4 (97.1 mg, 0.30 mmol). The resulting pale-yellow
solution was stirred for 24 h at room temperature. The solution was
filtered through Celite to yield a red solution, which was concentrated
under vacuum. Storage at −24 °C for several weeks yielded 10 as a
few orange crystals suitable for X-ray crystallography, along with the
red crystals of [Cu(Me-bpy)2]BF4 (Me-bpy = 6,6′-dimethyl-2,2′-
bipyridyl; see the SI) and a black precipitate.
Synthesis of 11a·CH3CN. Bi(6-Me-2-py)3(1) (100 mg, 0.20
mmol) was dissolved in MeCN (5 mL). To this solution was added
CuCl2 (27.7 mg, 0.20 mmol). The resulting red solution was stirred
for 15 min at rt. The solution was filtered through Celite to yield a red
solution, which was concentrated under vacuum, and slow diffusion of
diethyl ether (5 mL) at −24 °C yielded 11a·CH3CN as red pale
crystals suitable for X-ray crystallography. 11a·CH3CN yield
1
6. Yield 59.2 mg (0.12 mmol, 64%). H NMR (298 K, CDCl3, 500
MHz): δ = 8.51 (br, 3H, H6 py), 7.58 (d, J = 7.70 Hz, 3H, H3), 7.43
(dd, J = 2.0/7.70 Hz, 3H, H4), 2.26 (s, 9H, H7 Me). HR-MS [Maldi,
positive ion mode Maldi-TOF]: m/z for C18H18BiN3 [M + H]+ calcd:
486.1377. Found: 486.1388 (1.1 ppm error).
1
(calculated as 11a·CH3CN): 48 mg (0.078 mmol, 40%). H NMR
Synthesis of Silver Complexes 8·X (X = OTf, BF4, PF6). The
corresponding silver salt (0.144 mmol) (36.99 mg, 28.03 mg, and
36.40 mg for AgOTf, AgBF4, and AgPF6, respectively) was dissolved
in MeCN (5 mL) in the dark. After stirring the mixture for 1 h, all
volatiles were removed under vacuum, and the resulting white solid
was dissolved in THF (5 mL). Bi(6-Me-2-py)3 (1) (70 mg, 0.144
mmol) in THF (3 mL) was added to give a white precipitate. The
solvents were evaporated, the residue was dissolved in MeCN (5 mL),
and the solution was concentrated until the formation of a white
precipitate was observed, which was redissolved by gentle heating.
Storage at −24 °C yielded 8·OTf·CH3CN, 8·BF4, and 8·PF6·2CH3CN
as colorless crystals suitable for X-ray crystallography. Crystalline yield
(calculated for all crystals): 62.6 mg (0.076 mmol, 53%), 60.5 mg
(0.084 mmol, 60%), and 58.5 mg (0.068 mmol, 47%), respectively.
The crystals were found to be very unstable toward light and
moisture, resulting in loss of crystallinity and the rapid formation of a
(298 K, MeCN-d3, 500 MHz): δ = 8.20 (d, J = 7.70 Hz, 2H, H3 py),
7.91 (t, J = 7.70 Hz, 2H, H4 py), 7.32 (d, J = 7.70 Hz, 2H, H5 py),
2.79 (s, 6H, H7 Me). 13C{1H} NMR (298 K, MeCN-d3, 100.6 MHz):
δ = 216.6 (br, C2 py), 163.5 (C6 py), 139.0 (C4 py), 135.4 (C3 py),
124.4 (C5 py), 26.0 (C7 Me). Elemental analysis (%) calcd for 11a·
CH3CN (C16H18BiCl2CuN4): C 31.5, H 3.0, N 9.2. Found C 31.0, H
2.9, N 8.6. HR-MS [Maldi, positive ion mode Maldi-TOF]: m/z for
C12H12BiClN2Cu [M-Cl-CH3CN]+ calcd: 490.9783. Found:
490.9762 (−2.1 ppm error).
Synthesis of 11b. Bi(6-CF3-2-py)3 (3) (200 mg, 0.30 mmol) was
dissolved in MeCN (5 mL). To this solution was added CuCl2 (124.6
mg, 0.90 mmol). The resulting pale-yellow solution was stirred
overnight at rt. The solution was filtered through Celite to yield a
yellow solution, which was concentrated under vacuum, and slow
diffusion of diethyl ether (5 mL) at −24 °C yielded 11b as yellow
blocks suitable for X-ray crystallography. Samples were found to
contain variable amounts of the ligand Bi(6-CF3-2-py)3 as
demonstrated by crystallography and NMR studies. For this reason,
a specific yield cannot be provided. 1H NMR (298 K, MeCN-d3, 500
MHz): δ = 8.47 (d, J = 7.80 Hz, 2H, H3 py), 8.20 (t, J = 7.80 Hz, 2H,
H4 py), 7.76 (d, J = 7.80 Hz, 2H, H5 py).
1
black amorphous solid, which hampered elemental analysis. H and
13C NMR spectra for 8·X were found to be identical within the
experimental error. 1H NMR (298 K, MeCN-d3, 500 MHz): δ = 7.83
(d, J = 7.40 Hz, 3H, H3 py), 7.76 (t, J = 7.40 Hz, 3H, H4 py), 7.32 (d,
J = 7.40 Hz, 3H, H5 py), 2.74 (s, 9H, H7 Me). 13C{1H} NMR (298 K,
MeCN-d3, 100.6 MHz): δ = 194.2 (br, C2 py), 161.9 (C6 py), 137.9
(C4 py), 133.5 (C3 py), 124.0 (C5 py), 25.8 (C7 Me). 8·OTf: 19F
NMR (298 K, MeCN-d3, 376 MHz): δ = −79.25 (s, 3F, OTf−). 8·
BF4: 19F NMR (298 K, MeCN-d3, 376 MHz): δ = −151.71 (br,
Synthesis of 11c·CH2Cl2. Bi(6-Me-2-py)3 (100 mg, 0.20 mmol)
was dissolved in MeCN (5 mL). To this solution was added CuBr2
(46 mg, 0.20 mmol). The resulting red solution was stirred for 15 min
at rt. The solution was filtered through Celite to yield a red solution,
which was concentrated under vacuum. Slow diffusion of diethyl ether
(5 mL) at −24 °C yielded 11c·CH2Cl2 as pale red crystals suitable for
X-ray crystallography. Yield (calculated as 11c·CH2Cl2) 36.8 mg
−
−
10BF4 ), −151.76 (br, 11BF4 ). 8·PF6: 19F NMR (298 K, MeCN-d3,
−
376 MHz): δ = −72.8 (d, 6F, JPF = 707 Hz, PF6 ). HR-MS [Maldi,
positive ion mode Maldi-TOF]: m/z for C18H18AgBiN3 [8-CH3N]+
calcd: 592.035. Found: 592.0349 (−0.1 ppm error).
1
(0.049 mmol, 24%). H NMR (298 K, MeCN-d3, 500 MHz): δ =
Synthesis of 9·BF4. AgBF4 (14.49 mg, 0.074 mmol) was dissolved
in MeCN (2 mL) in the dark. After 30 min of stirring, all volatiles
were removed under vacuum, and the resulting white solid was
redissolved in THF (2 mL). Then, Bi(6-Ph-2-py)3 (4) (50 mg, 0.074
mmol) in THF (2 mL) was added to give a white precipitate.
8.35 (d, J = 7.80 Hz, 2H, H3 py), 7.88 (t, J = 7.80 Hz, 2H, H4 py),
7.35 (d, J = 7.80 Hz, 2H, H5 py), 2.79 (s, 6H, H7 Me). 13C{1H} NMR
(298 K, MeCN-d3, 100.6 MHz): δ = 212.2 (br, C2 py), 163.6 (C6 py),
139.0 (C4 py), 137.0 (C3 py), 124.5 (C5 py), 25.9 (C7 Me). HR-MS
K
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
[Maldi, positive ion mode Maldi-TOF]: m/z for C12H12BiBrN2Cu
[M-Br-CH3CN]+ calcd: 536.9259. Found: 536.926 (0.1 ppm error).
Synthesis of 12. Inside a N2 filled glovebox, a Schlenk tube was
charged with Bi(6-Me-2-py)3 (1) (200 mg, 0.41 mmol) and FeCl2 (52
mg, 0.41 mmol) and transferred to a Schlenk line. Twenty milliliters
of THF was added. The resulting pale orange solution was stirred
overnight at room temperature. An orange solution with a small
amount of brown precipitate formed overnight and was removed by
filtration. The clear orange filtrate was concentrated under vacuum to
approximately 5 mL. Storage at −20 °C yielded a few yellow crystals
suitable for X-ray crystallography.
Synthesis of 13. FeI2 (92.8 mg, 0.30 mmol) was dissolved in
THF (5 mL). To this black solution was added Bi(6-Me-2-py)3 3 (1)
(150 mg, 0.30 mmol). The resulting brown suspension was stirred
overnight at room temperature. All volatiles were removed under
vacuum, and the resulting solid residue was redissolved in MeCN (5
mL). This suspension was filtered through Celite, which was
redissolved by gentle heating. Storage overnight at −24 °C yielded
13 as a few yellow crystals suitable for X-ray crystallography.
Synthesis of 14·OTf. (PPh)3AuOTf (15.9 mg, 0.032 mmol) and
Bi(6-Me-2-py)3 were dissolved in acetone (2 mL). Then, a solution of
Bi(6-Me-2-py)3 3 (1) (20 mg, 0.032 mmol) was added. After stirring
for 30 min at room temperature, the colorless solution was
concentrated under vacuum. Storage at −24 °C yielded 14 as a few
colorless blocks suitable for X-ray crystallography.
Andrew D. Bond − Department of Chemistry, University of
Cambridge, Cambridge CB2 1EW, U.K.; orcid.org/0000-
0002-1744-0489
Complete contact information is available at:
https://pubs.acs.org/10.1021/acs.inorgchem.0c00579
Author Contributions
The manuscript was written through contributions of all
authors.
Notes
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
■
We thank The Leverhulme Trust (R.G.-R., DSW) (RPG-2017-
146), the Cambridge Trust (Vice Chancellor Scholarship for
A.J.P.), and The Spanish Ministry of Science, Innovation and
Universities (MCIU) (project numbers PGC2018-096880-A-
I00, MCIU/AEI/FEDER, UE and PGC2018-099470-B-I00,
MCIU/AEI/FEDER, UE) for funding. R.G.-R. acknowledges
the Spanish MINECO/AEI and the European Union (ESF)
for a Ramon y Cajal contract (RYC-2015-19035). We thank
Alberto Diez-Varga for help in collecting some of the mass
data.
ASSOCIATED CONTENT
■
REFERENCES
sı
■
* Supporting Information
(1) Moberg, C. C3 Symmetry in Asymmetric Catalysis and Chiral
Recognition. Angew. Chem., Int. Ed. 1998, 37 (3), 248−268.
(2) Trofimenko, S. Recent Advances in Poly(Pyrazolyl)Borate
(Scorpionate) Chemistry. Chem. Rev. 1993, 93 (3), 943−980.
(3) Szczepura, L. F.; Witham, L. M.; Takeuchi, K. J. Tris(2-Pyridyl)
Tripod Ligands. Coord. Chem. Rev. 1998, 174 (1), 5−32.
(4) Maleckis, A.; Kampf, J. W.; Sanford, M. S. A Detailed Study of
Acetate-Assisted C-H Activation at Palladium(IV) Centers. J. Am.
Chem. Soc. 2013, 135 (17), 6618−6625.
The Supporting Information is available free of charge at
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c00579.
NMR spectra, additional X-ray structures, details and
information, and HR-MS data (PDF)
Accession Codes
CCDC 1981115−1981137 contain the supplementary crys-
tallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by
emailing data_request@ccdc.cam.ac.uk, or by contacting The
Cambridge Crystallographic Data Centre, 12 Union Road,
Cambridge CB2 1EZ, UK; fax: +44 1223 336033.
(5) Walden, A. G.; Miller, A. J. M. Rapid Water Oxidation
Electrocatalysis by a Ruthenium Complex of the Tripodal Ligand
Tris(2-Pyridyl)Phosphine Oxide. Chem. Sci. 2015, 6 (4), 2405−2410.
(6) Camasso, N. M.; Sanford, M. S. Design, Synthesis, and Carbon-
Heteroatom Coupling Reactions of Organometallic Nickel(IV)
Complexes. Science 2015, 347 (6227), 1218−1220.
́
(7) Martínez-García, H.; Morales, D.; Perez, J.; Puerto, M.; del Río,
AUTHOR INFORMATION
■
I. Interaction between Anions and Cationic Metal Complexes
Containing Tridentate Ligands with Exo-C-H Groups: Complex
Stability and Hydrogen Bonding. Chem. - Eur. J. 2014, 20 (19),
5821−5834.
Corresponding Authors
́
Celedonio M. Alvarez − GIR MIOMeT-IU, Cinquima,
́
́
Quımica Inorganica, Facultad de Ciencias, Universidad de
Valladolid, 47011 Valladolid, Spain; orcid.org/0000-0003-
4431-6501; Email: celedonio.alvarez@uva.es
(8) Reichart, F.; Kischel, M.; Zeckert, K. Lanthanide(II) Complexes
of a Dual Functional Tris(2-Pyridyl)Stannate Derivative. Chem. - Eur.
J. 2009, 15 (39), 10018−10020.
́
Raul García-Rodríguez − GIR MIOMeT-IU, Cinquima,
(9) García, F.; Hopkins, A. D.; Humphrey, S. M.; McPartlin, M.;
Rogers, M. C.; Wright, D. S. The First Example of a Si-Bridged
Tris(Pyridyl) Ligand; Synthesis and Structure of [MeSi(2-
C5H4N)3LiX] (X = 0.2Br, 0.8Cl). Dalt. Trans. 2004, No. 3, 361−362.
́
́
Quımica Inorganica, Facultad de Ciencias, Universidad de
Valladolid, 47011 Valladolid, Spain; orcid.org/0000-0003-
0699-3894; Email: raul.garcia.rodriguez@uva.es
́
(10) Morales, D.; Perez, J.; Riera, L.; Riera, V.; Miguel, D.
Authors
Molybdenum and Tungsten Tricarbonyl Complexes with the
Tripodal Ligands [nBuSn(2-Pyridyl)3] and [RSn(Methylthio-
methyl)3]. Organometallics 2001, 20 (22), 4517−4523.
́
Alvaro García-Romero − GIR MIOMeT-IU, Cinquima,
́
́
Quımica Inorganica, Facultad de Ciencias, Universidad de
(11) García-Rodríguez, R.; Kopf, S.; Wright, D. S. Modifying the
Donor Properties of Tris(Pyridyl)Aluminates in Lanthanide(II)
Sandwich Compounds. Dalt. Trans. 2018, 47 (7), 2232−2239.
(12) Zeckert, K. Pyridyl Compounds of Heavier Group 13 and 14
Elements as Ligands for Lanthanide Metals. Organometallics 2013, 32
(5), 1387−1393.
Valladolid, 47011 Valladolid, Spain
Alex J. Plajer − Department of Chemistry, University of
Cambridge, Cambridge CB2 1EW, U.K.
́
Daniel Miguel − GIR MIOMeT-IU, Cinquima, Quımica
́
Inorganica, Facultad de Ciencias, Universidad de Valladolid,
47011 Valladolid, Spain; orcid.org/0000-0003-0650-3058
Dominic S. Wright − Department of Chemistry, University of
Cambridge, Cambridge CB2 1EW, U.K.; orcid.org/0000-
0002-9952-3877
(13) Beswick, M. A.; Davies, M. K.; Raithby, P. R.; Steiner, A.;
Wright, D. S. Synthesis and Structure of [Pb(2-Py)3Li·THF],
Containing a Low-Valent Group 14 Tris(Pyridyl) Ligand (2-Py =
2-Pyridyl). Organometallics 1997, 16 (6), 1109−1110.
L
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
(14) Alvarez, C. S.; García, F.; Humphrey, S. M.; Hopkins, A. D.;
Kowenicki, R. A.; McPartlin, M.; Layfield, R. A.; Raja, R.; Rogers, M.
C.; Woods, A. D.; Wright, D. S. Highly Selective Epoxidation of
Styrene Using a Transition Metal-Aluminium(III) Complex Contain-
ing the [MeAl(2-Py)3]− Anion (2-Py = 2-Pyridyl). Chem. Commun.
2005, 0 (2), 198−200.
(32) García-Rodríguez, R.; Wright, D. S. Direct Synthesis of the
Janus-Head Ligand (MePy)3Sn-Sn(MePy)3 Using an Unusual Pyridyl-
Transfer Reaction (MePy = 6-Methyl-2-Pyridyl). Dalt. Trans. 2014, 43
(39), 14529−14532.
(33) García, F.; Hopkins, A. D.; Kowenicki, R. A.; McPartlin, M.;
Rogers, M. C.; Wright, D. S. Synthesis of the [MeAl(2-Py)3]− Anion
and Its Application as a Stable and Mild Pyridyl-Transfer Reagent (2-
Py = 2-Pyridyl). Organometallics 2004, 23 (16), 3884−3890.
(34) García-Rodríguez, R.; Hanf, S.; Bond, A. D.; Wright, D. S. A
Non-Chiral Lithium Aluminate Reagent for the Determination of
Enantiomeric Excess of Chiral Alcohols. Chem. Commun. 2017, 53
(7), 1225−1228.
(35) Szczepura, L. F.; Witham, L. M.; Takeuchi, K. J. Tris(2-Pyridyl)
Tripod Ligands. Coord. Chem. Rev. 1998, 174 (1), 5−32.
(36) Hanf, S.; García-Rodríguez, R.; Bond, A. D.; Hey-Hawkins, E.;
Wright, D. S. Sterically-Constrained Tripodal Phosphorus-Bridged
Tris-Pyridyl Ligands. Dalt. Trans. 2016, 45 (1), 276−283.
(37) Gneuß, T.; Leitl, M. J.; Finger, L. H.; Rau, N.; Yersin, H.;
Sundermeyer, J. A New Class of Luminescent Cu(I) Complexes with
Tripodal Ligands-TADF Emitters for the Yellow to Red Color Range.
Dalt. Trans. 2015, 44 (18), 8506−8520.
(15) Zeckert, K.; Griebel, J.; Kirmse, R.; Weiß, M.; Denecke, R.
Versatile Reactivity of a Lithium Tris(Aryl)Plumbate(II) towards
Organolanthanoid Compounds: Stable Lead-Lanthanoid-Metal Bonds
or Redox Processes. Chem. - Eur. J. 2013, 19 (24), 7718−7722.
(16) Schrader, I.; Zeckert, K.; Zahn, S. Dilithium Hexaorgano-
stannate(IV) Compounds. Angew. Chem., Int. Ed. 2014, 53 (50),
13698−13700.
́
(17) Plajer, A. J.; Colebatch, A. L.; Enders, M.; García-Romero, A.;
Bond, A. D.; García-Rodríguez, R.; Wright, D. S. The Coordination
Chemistry of the Neutral Tris-2-Pyridyl Silicon Ligand [PhSi(6-Me-2-
Py)3]. Dalt. Trans. 2018, 47 (20), 7036−7043.
(18) Zeckert, K.; Zahn, S.; Kirchner, B. Tin-Lanthanoid Donor-
Acceptor Bonds. Chem. Commun. 2010, 46 (15), 2638−2640.
(19) García-Rodríguez, R.; Bullock, T. H.; McPartlin, M.; Wright, D.
S. Synthesis and Structures of Tris(2-Pyridyl)Aluminate Sandwich
Compounds [{RAl(2-Py′)2}2M] (Py′ = 2-Pyridyl, M = Ca, Mn, Fe).
Dalt. Trans. 2014, 43 (37), 14045−14053.
(38) Ni, J.; Wei, K. J.; Min, Y.; Chen, Y.; Zhan, S.; Li, D.; Liu, Y.
Copper(I) Coordination Polymers of 2,2′-Dipyridylamine Deriva-
tives: Syntheses, Structures, and Luminescence. Dalt. Trans. 2012, 41
(17), 5280−5293.
(20) García-Rodríguez, R.; Simmonds, H. R.; Wright, D. S.
Formation of a Heterometallic AlIII/SmIII Complex Involving a
Novel [EtAl(2-Py)2O]2‑ Ligand (2-Py = 2-Pyridyl). Organometallics
2014, 33 (24), 7113−7117.
́
(39) Perez, J.; Morales, D.; García-Escudero, L. A.; Martínez-García,
H.; Miguel, D.; Bernad, P. Synthesis of New Copper(I) Complexes
with Tris(2-Pyridyl) Ligands. Applications to Carbene and Nitrene
Transfer Reactions. J. Chem. Soc. Dalt. Trans. 2009, 1 (2), 375−382.
(40) Yang, W.; Schmider, H.; Wu, Q.; Zhang, Y. S.; Wang, S.
Syntheses, Structures, and Fluxionality of Blue Luminescent Zinc(II)
Complexes: Zn(2,2’,2-Tpa)Cl2, Zn(2,2’,2-Tpa)2(O2CCF3)2, and Zn-
(2,2’,3-Tpa)4(O2CCF3)2 (Tpa = Tripyridylamine). Inorg. Chem.
2000, 39 (11), 2397−2404.
(21) Matson, B. D.; Peters, J. C. Fe-Mediated HER vs N2RR:
E
Exploring Factors That Contribute to Selectivity in P3 Fe(N2) (E = B,
Si, C) Catalyst Model Systems. ACS Catal. 2018, 8 (2), 1448−1455.
(22) Thomas, J. C.; Peters, J. C. Zwitterionic and Cationic
Bis(Phosphine) Platinum(II) Complexes: Structural, Electronic, and
Mechanistic Comparisons Relevant to Ligand Exchange and Benzene
C-H Activation Processes. J. Am. Chem. Soc. 2003, 125 (29), 8870−
8888.
(41) Keene, F. R.; Stephenson, P. J.; Snow, M. R.; Tiekink, E. R. T.
Ruthenium(II) Complexes of the C3υ Ligands Tris(2-Pyridyl)Amine,
Tris(2-Pyridyl)Methane, and Tris(2-Pyridyl)Phosphine. 1. Synthesis
and X-Ray Structural Studies of the Bis(Ligand) Complexes. Inorg.
Chem. 1988, 27 (12), 2040−2045.
(42) Hanf, S.; García-Rodríguez, R.; Feldmann, S.; Bond, A. D.;
Hey-Hawkins, E.; Wright, D. S. Multidentate 2-Pyridyl-Phosphine
Ligands-towards Ligand Tuning and Chirality. Dalt. Trans. 2017, 46
(3), 814−824.
(43) Steiner, A.; Stalke, D. Substituent-Controlled Reactions of
Iminophosphoranes with Methyllithium. Angew. Chem., Int. Ed. Engl.
1995, 34 (16), 1752−1755.
(44) Steiner, A.; Stalke, D. Bis(2-Pyridyl)Phosphides and -Arsenides
of Group 13 Metals: Substituent-Separated Contact Ion Pairs.
Organometallics 1995, 14 (5), 2422−2429.
(45) Artem’ev, A. V.; Doronina, E. P.; Rakhmanova, M. I.; Sutyrina,
A. O.; Bagryanskaya, I. Y.; Tolstoy, P. M.; Gushchin, A. L.; Mazur, A.
S.; Gusarova, N. K.; Trofimov, B. A. Luminescent CuI Thiocyanate
Complexes Based on Tris(2-Pyridyl)Phosphine and Its Oxide: From
Mono-, Di- and Trinuclear Species to Coordination Polymers. New J.
Chem. 2016, 40 (12), 10028−10040.
(46) Suter, R.; Sinclair, H.; Burford, N.; McDonald, R.; Ferguson, M.
J.; Schrader, E. Tris(2-Pyridyl)Phosphine as a Versatile Ligand for
Pnictogen Acceptors. Dalt. Trans. 2017, 46 (24), 7681−7685.
(47) Dedert, P. L.; Thompson, J. S.; Ibers, J. A.; Marks, T. J. Metal
Ion Binding Sites Composed of Multiple Nitrogenous Heterocycles.
Synthesis and Spectral and Structural Study of Bis(2,2′,2″-
Tripyridylamine)Copper(II) Bis(Trifluoromethanesulfonate) and Its
Bis(Acetonitrile) Adduct. Inorg. Chem. 1982, 21 (3), 969−977.
(48) Dedert, P. L.; Sorrell, T.; Marks, T. J.; Ibers, J. A. Oxygenation
of [Tris(2-Pyridyl)Amine](Trifluoromethanesulfonato)Copper(I) in
Nonaqueous Solvents. Synthesis and Structural Characterization of
the Cubane-like Cluster [Cu4(OH)4(SO3CF3)2[N(C5H4N)3]4]-
[SO3CF3]2·C3H6O. Inorg. Chem. 1982, 21 (9), 3506−3517.
(23) Del Castillo, T. J.; Thompson, N. B.; Peters, J. C. A Synthetic
Single-Site Fe Nitrogenase: High Turnover, Freeze-Quench 57Fe
̈
Mossbauer Data, and a Hydride Resting State. J. Am. Chem. Soc. 2016,
138 (16), 5341−5350.
(24) Simmonds, H. R.; Wright, D. S. Main Group Pyridyl-Based
Ligands; Strategies to Mixed Metal Complexes. Chem. Commun.
2012, 48 (69), 8617.
̈
(25) Plajer, A. J.; Colebatch, A. L.; Rizzuto, F. J.; Prohm, P.; Bond,
A. D.; García-Rodríguez, R.; Wright, D. S. How Changing the
Bridgehead Can Affect the Properties of Tripodal Ligands. Angew.
Chem., Int. Ed. 2018, 57 (22), 6648−6652.
̈
(26) Cui, C.; Lalancette, R. A.; Jakle, F. The Elusive Tripodal Tris(2-
Pyridyl)Borate Ligand: A Strongly Coordinating Tetraarylborate.
Chem. Commun. 2012, 48 (55), 6930−6932.
̈
(27) Cui, C.; Shipman, P. R.; Lalancette, R. A.; Jakle, F. Tris(2-
Pyridylborate) (Tpyb) Metal Complexes: Synthesis, Characterization,
and Formation of Extrinsically Porous Materials with Large
Cylindrical Channels. Inorg. Chem. 2013, 52 (16), 9440−9448.
(28) Jeong, S. Y.; Lalancette, R. A.; Lin, H.; Lupinska, P.; Shipman,
̈
P. O.; John, A.; Sheridan, J. B.; Jakle, F. third-Generation”-Type
Functional Tris(2-Pyridyl)Borate Ligands and Their Transition-Metal
Complexes. Inorg. Chem. 2016, 55 (7), 3605−3615.
(29) García-Rodríguez, R.; Wright, D. S. Steric Effects on the
Structures, Reactivity, and Coordination Chemistry of Tris(2-
Pyridyl)Aluminates. Chem. - Eur. J. 2015, 21 (42), 14949−14957.
(30) Plajer, A. J.; Kopf, S.; Colebatch, A. L.; Bond, A. D.; Wright, D.
S.; García-Rodríguez, R. Deprotonation, Insertion and Isomerisation
in the Post-Functionalisation of Tris-Pyridyl Aluminates. Dalt. Trans.
2019, 48 (17), 5692−5697.
́
́
(31) García-Romero, A.; Plajer, A. J.; Alvarez-Miguel, L.; Bond, A.
D.; Wright, D. S.; García-Rodríguez, R. Postfunctionalization of
Tris(Pyridyl) Aluminate Ligands: Chirality, Coordination, and
Supramolecular Chemistry. Chem. - Eur. J. 2018, 24 (64), 17019−
17026.
M
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry
pubs.acs.org/IC
Article
(49) Ross, S.; Weyhermu
̈
ller, T.; Bill, E.; Wieghardt, K.; Chaudhuri,
(67) Silvestru, C.; Breunig, H. J.; Althaus, H. Structural Chemistry of
Bismuth Compounds. I. Organobismuth Derivatives. Chem. Rev.
1999, 99 (11), 3277−3327.
(68) Suzuki, H.; Matano, Y., Eds.; Organobismuth(III) Compounds.
In Organobismuth Chemistry; Elsevier Science: Amsterdam, 2001;
Chapter 2, pp 21−245, DOI: 10.1016/B978-044420528-5/50004-5.
(69) Bondi, A. Van Der Waals Volumes and Radii. J. Phys. Chem.
1964, 68 (3), 441−451.
(70) Mantina, M.; Chamberlin, A. C.; Valero, R.; Cramer, C. J.;
Truhlar, D. G. Consistent van Der Waals Radu for the Whole Main
̈
Group. J. Phys. Chem. A 2009, 113 (19), 5806−5812.
(71) Charton, M. Organic and Biological Chemistry: The Nature of
the Ortho Effect. II. Composition of the Taft Steric Parameters. J. Am.
Chem. Soc. 1969, 91 (3), 615−618.
P. Tris(Pyridinealdoximato)Metal Complexes as Ligands for the
Synthesis of Asymmetric Heterodinuclear CrIIIM Species [M =
Zn(II), Cu(II), Ni(II), Fe(II), Mn(II), Cr(II), Co(III)]: A Magneto-
Structural Study. Inorg. Chem. 2001, 40 (26), 6656−6665.
(50) Suzuki, H.; Matano, Y., Eds.; Introduction. In Organobismuth
Chemistry; Elsevier Science, Amsterdan, 2001; Chapter 1, pp 1−20,
DOI: 10.1016/B978-044420528-5/50003-3.
(51) Stephens, L. J.; Munuganti, S.; Duffin, R. N.; Werrett, M. V.;
Andrews, P. C. Is Bismuth Really the “Green” Metal? Exploring the
Antimicrobial Activity and Cytotoxicity of Organobismuth Thiolate
Complexes. Inorg. Chem. 2020, 59 (6), 3494−3508.
(52) Mohan, R. Green Bismuth. Nat. Chem. 2010, 2 (4), 336.
(53) Lichtenberg, C.; Pan, F.; Spaniol, T. P.; Englert, U.; Okuda, J.
The Bis(Allyl)Bismuth Cation: A Reagent for Direct Allyl Transfer by
Lewis Acid Activation and Controlled Radical Polymerization. Angew.
Chem., Int. Ed. 2012, 51 (52), 13011−13015.
(54) Chitnis, S. S.; Robertson, A. P. M.; Burford, N.; Patrick, B. O.;
McDonald, R.; Ferguson, M. J. Bipyridine Complexes of E3+ (E = P,
As, Sb, Bi): Strong Lewis Acids, Sources of E(OTf)3 and Synthons for
EI and EV Cations. Chem. Sci. 2015, 6 (11), 6545−6555.
(55) Solyntjes, S.; Neumann, B.; Stammler, H. G.; Ignat’ev, N.;
Hoge, B. Bismuth Perfluoroalkylphosphinates: New Catalysts for
Application in Organic Syntheses. Chem. - Eur. J. 2017, 23 (7), 1568−
1575.
(56) Wang, F.; Planas, O.; Cornella, J. Bi(I)-Catalyzed Transfer-
Hydrogenation with Ammonia-Borane. J. Am. Chem. Soc. 2019, 141
(10), 4235−4240.
(57) Yin, S. F.; Maruyama, J.; Yamashita, T.; Shimada, S. Efficient
Fixation of Carbon Dioxide by Hypervalent Organobismuth Oxide,
Hydroxide, and Alkoxide. Angew. Chem., Int. Ed. 2008, 47 (35),
6590−6593.
(58) Casely, I. J.; Ziller, J. W.; Fang, M.; Furche, F.; Evans, W. J.
Facile Bismuth-Oxygen Bond Cleavage, C-H Activation, and
Formation of a Monodentate Carbon-Bound Oxyaryl Dianion,
(C6H2tBu2−3,5-O-4)2‑. J. Am. Chem. Soc. 2011, 133 (14), 5244−
5247.
(72) Artem’Ev, A. V.; Bagryanskaya, I. Y.; Doronina, E. P.; Tolstoy,
P. M.; Gushchin, A. L.; Rakhmanova, M. I.; Ivanov, A. Y.; Suturina, A.
O. A New Family of Clusters Containing a Silver-Centered
Tetracapped [Ag@Ag4(μ3-P)4] Tetrahedron, Inscribed within a N12
Icosahedron. Dalt. Trans. 2017, 46 (37), 12425−12429.
(73) Lin, T. P.; Ke, I. S.; Gabbaï, F. P. σ-Accepting Properties of a
Chlorobismuthine Ligand. Angew. Chem., Int. Ed. 2012, 51 (20),
4985−4988.
́
́
(74) Fernandez, E. J.; Laguna, A.; Lopez-De-Luzuriaga, J. M.;
́
Monge, M.; Nema, M.; Olmos, M. E.; Perez, J.; Silvestru, C.
Experimental and Theoretical Evidence of the First Au(I)···Bi(III)
Interaction. Chem. Commun. 2007, 028 (6), 571−573.
(75) Tschersich, C.; Braun, B.; Herwig, C.; Limberg, C.
Coordination of Noble Metals by an Ambiphilic PBiP Pincer Ligand:
Metallophilic Bi-Cu and Bi-Ag Interactions. J. Organomet. Chem.
2015, 784, 62−68.
(76) Burke, P. J.; Mcmillin, D. R.; Robinson, W. R. Crystal and
Molecular Structure of Bis(6, 6’-Dimethyl-2, 2’-Bipyridyl)Copper(I)
Tetrafluoroborate. Inorg. Chem. 1980, 19 (5), 1211−1214 Further
information regarding the structure reported in this paper can be
found in the SI..
(77) Parks, J. E.; Wagner, B. E.; Holm, R. H. Syntheses Employing
Pyridyllithium Reagents: New Routes to 2,6-Disubstituted Pyridines
and 6,6′-Disubstituted 2,2′-Bipyridyls. J. Organomet. Chem. 1973, 56
(C), 53−66.
(78) Whitesides, G. M.; Casey, C. P.; Krieger, J. K. The Thermal
Decomposition of Vinylic Copper(I) and Silver(I) Organometallic
Compounds. J. Am. Chem. Soc. 1971, 93 (6), 1379−1389.
(79) Suzuki, H.; Matano, Y., Eds.; Bismuth Compounds in Organic
Transformations. In Organobismuth Chemistry; Elsevier Science:
Amsterdam, 2001; Chapter 5, pp 371−440, DOI: 10.1016/B978-
044420528-5/50007-0.
(80) Matano, Y.; Nomura, H. Facile Oxidation of Alcohols to
Carbonyl. Angew. Chem., Int. Ed. 2002, 41 (16), 3028−3031.
(81) Beswick, M. A.; Lawson, Y. G.; Raithby, P. R.; Wood, J. A.;
Wright, D. S. A Metallated Primary Arsine; Synthesis and Structure of
[PhAsHLi·2tHf]∞. J. Chem. Soc., Dalton Trans. 1999, No. 12, 1921−
1922.
(82) Janiak, C.; Chamayou, A. C.; Royhan Uddin, A. K. M.; Uddin,
M.; Hagen, K. S.; Enamullah, M. Polymorphs, Enantiomorphs,
Chirality and Helicity in [Rh{N, O}(η4-Cod)] Complexes with {N,
O} = Salicylaldiminato Schiff Base or Aminocarboxylato Ligands. J.
Chem. Soc. Dalt. Trans. 2009, 9226 (19), 3698−3709.
(83) Daniels, C. L.; Mendivelso-Perez, D. L.; Rosales, B. A.; You, D.;
Sahu, S.; Jones, J. S.; Smith, E. A.; Gabbaï, F. P.; Vela, J.
Heterobimetallic Single-Source Precursors: A Springboard to the
Synthesis of Binary Intermetallics. ACS Omega 2019, 4 (3), 5197−
5203.
(84) Daniels, C. L.; Knobeloch, M.; Yox, P.; Adamson, M. A. S.;
Chen, Y.; Dorn, R. W.; Wu, H.; Zhou, G.; Fan, H.; Rossini, A. J.; Vela,
J. Intermetallic Nanocatalysts from Heterobimetallic Group 10−14
Pyridine-2-Thiolate Precursors. Organometallics 2020, 39, 1092.
(85) Schuster, O.; Schier, A.; Schmidbaur, H. The Quest for
Complexes with a Coordinative Gold-Bismuth Bond. Organometallics
2003, 22 (20), 4079−4083.
(59) Toma, A. M.; Rat,̧ C. I.; Pavel, O. D.; Hardacre, C.; Ruffer, T.;
̈
̂
Lang, H.; Mehring, M.; Silvestru, A.; Parvulescu, V. I. Heterocyclic
Bismuth(III) Compounds with Transannular N→Bi Interactions as
Catalysts for the Oxidation of Thiophenol to Diphenyldisulfide. Catal.
Sci. Technol. 2017, 7 (22), 5343−5353.
(60) Planas, O.; Wang, F.; Leutzsch, M. H. Fluorination of
arylboronic esters enabled by bismuth redox catalysis. Science 2020,
367 (6475), 313−317.
(61) Christianson, A. M.; Gabbaï, F. P. Antimony- and Bismuth-
Based Materials and Applications. In Main Group Strategies Towards
̈
Functional Hybrid Materials; Baumgartner, T., Jakle, F., Eds.;Wiley:
Germany, 2017; pp 405−432, DOI: 10.1002/9781119235941.ch16.
(62) Tschersich, C.; Limberg, C.; Roggan, S.; Herwig, C.; Ernsting,
N.; Kovalenko, S.; Mebs, S. Gold- and Platinum-Bismuth Donor-
Acceptor Interactions Supported by an Ambiphilic PBiP Pincer
Ligand. Angew. Chem., Int. Ed. 2012, 51 (20), 4989−4992.
(63) Ke, I. S.; Gabbaï, F. P. σ-Donor/Acceptor-Confused Ligands:
The Case of a Chlorostibine. Inorg. Chem. 2013, 52 (12), 7145−7151.
(64) Tschersich, C.; Hoof, S.; Frank, N.; Herwig, C.; Limberg, C.
The Effect of Substituents at Lewis Acidic Bismuth(III) Centers on
Its Propensity to Bind a Noble Metal Donor. Inorg. Chem. 2016, 55
(4), 1837−1842.
(65) Materne, K.; Hoof, S.; Frank, N.; Herwig, C.; Limberg, C. In
Situ Formation of PBiP Ligands upon Complexation of a Mixed
Phosphane/Bismuthane with Group 11 Metal Ions. Organometallics
2017, 36 (24), 4891−4895.
(66) Urgin, K.; Aube, C.; Pichon, C.; Pipelier, M.; Blot, V.; Thobie-
Gautier, C.; Leonel, E.; Dubreuil, D.; Condon, S. Advanced
́
́
Preparation of Functionalized Triarylbismuths and Triheteroaryl-
Bismuths: New Scope and Alternatives. Tetrahedron Lett. 2012, 53
(15), 1894−1896.
N
https://dx.doi.org/10.1021/acs.inorgchem.0c00579
Inorg. Chem. XXXX, XXX, XXX−XXX