Synthesis, structure and anion binding properties of 1,8-bis(dimesitylboryl)anthracene and its monoborylated analog

Article abstract of DOI:10.1039/c9dt03238j

Two boranes, 1-(dimesitylboryl)anthracene (1) and 1,8-bis(dimesitylboryl)anthracene (2), have been synthesized with the spectrophysical properties showing how the inclusion of one or two boron atoms progressively perturbs the π-system of the anthracene backbone. This perturbation is caused by conjugation of the anthracene-π? orbital with the vacant p-orbital on boron. Additionally, both 1 and 2 have a high affinity for fluoride and cyanide anions which are complexed in a 1:1 guest-host ratio. The mono-borane 1 is particularly well-suited for cyanide binding, displaying a binding constant of 3 × 10⁷ in THF. Furthermore, as a result of their unique electronic structures, these boranes display a fluorescence response to fluoride anion characterized by a blue shift in the case of 1 and a red shift in the case of 2.

Full text of DOI:10.1039/c9dt03238j

View Article Online
View Journal
Dalton
Transactions
An international journal of inorganic chemistry
Accepted Manuscript
This article can be cited before page numbers have been issued, to do this please use: R.
Teerasarunyanon, L. Wilkins, G. Park and F. P. Gabbaï, Dalton Trans., 2019, DOI: 10.1039/C9DT03238J.
Volume 46
Number 10
14 March 2017
Pages 3073-3412
This is an Accepted Manuscript, which has been through the
Royal Society of Chemistry peer review process and has been
accepted for publication.
Dalton
Transactions
An international journal of inorganic chemistry
Accepted Manuscripts are published online shortly after acceptance,
before technical editing, formatting and proof reading. Using this free
rsc.li/dalton
service, authors can make their results available to the community, in
citable form, before we publish the edited article. We will replace this
Accepted Manuscript with the edited and formatted Advance Article as
soon as it is available.
You can find more information about Accepted Manuscripts in the
Information for Authors.
Please note that technical editing may introduce minor changes to the
text and/or graphics, which may alter content. The journal’s standard
Terms & Conditions and the Ethical guidelines still apply. In no event
ISSN 0306-0012
COMMUNICATION
Douglas W. Stephen et al.
shall the Royal Society of Chemistry be held responsible for any errors
N-Heterocyclic carbene stabilized parent sulfenyl, selenenyl,
and tellurenyl cations (XH+, X = S, Se, Te)
or omissions in this Accepted Manuscript or any consequences arising
from the use of any information it contains.
rsc.li/dalton

Please do not adjust margins
Page 1 of 7
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT03238J
Synthesis, structure and anion binding properties of 1,8-
bis(dimesitylboryl)anthracene and its monoborylated analog
Ratanakorn Teerasarunyanon,a,b Lewis C. Wilkins,a Gyeongjin Parka and François P. Gabbaï *a
Received 00th January 20xx,
Accepted 00th January 20xx
DOI: 10.1039/x0xx00000x
Two boranes, 1-(dimesitylboryl)anthracene (1) and 1,8- simple permutation affords more Lewis acidic boron moieties as
bis(dimesitylboryl)anthracene (2), have been synthesized with demonstrated by the formation of isolable complexes with
the spectrophysical properties showing how the inclusion of one or tetramethylethylene diamine and pyrimidine. In parallel to
two boron atoms progressively perturbs the -system of the these efforts, we have reported on the synthesis of related
anthracene. This is caused by conjugation of the  orbitals with large-bite diboranes based on the 1,8-triptycenediyl and 1,8-
the vacant p-orbital on boron. Additionally, both 1 and 2 display biphenylenediyl backbone.10 Our investigations of these
effective fluoride and cyanide complexation in a 1:1 guest-host systems have revealed that they are particularly well-suited for
ratio, with the mono-borane 1 being particularly potent for cyanide the complexation of the cyanide anion in a -1,2 fashion.10b
binding, displaying a binding constant of 3 x 107. Furthermore, both While carrying out these studies, it occurred to us that the
1 and 2 possess interesting fluorescence properties as a result of related diborane based on the 1,8-anthracenediyl scaffold had
the disrupted -system leading to a blue shift of 1 and a red shift of not been considered.11 In this paper, we fill this knowledge gap
2 upon fluoride coordination.
by describing the synthesis and properties of 1,8-
bis(dimesitylboryl)anthracene (2). We also report on the
Bifunctional boranes have attracted interest because of their properties of 1-(dimesitylboryl)anthracene (1).
ability to chelate anions1 or activate small molecules.2 The
B
B
B
B
Ph2
Cat
Cat
Ph2
separation between the boron atoms influences the binding
selectivity of these systems. The chelation of small monoanions
is typically favoured in the case of diboranes that are based on
the ortho-phenylene3 or 1,8-naphthalenediyl4 backbone. Such
compounds have been used in a number of applications
including anion sensing, 4b, c, 4e-g, i small molecule activation2d, 3h,
4h, 5 and catalysis.2a, 3c, d, 6 In the past few years, the synthesis of
diboranes featuring a larger separation has attracted renewed
interest. Building on the pioneering studies of Katz who
investigated several decades ago the synthesis of 1,8-
anthracenediethynyl-bis(catechol boronate) (I) as a bidentate
Lewis acid for the chelation of pyrimidines,7 several groups
including ours have investigated the synthesis and properties of
systems where two Lewis acidic diarylboryl moieties are
separated by more than 4 Å.8 The Mitzel group recently
described an analog of Katz’s compound (II) in which the two
boronate units are replaced by diphenylboryl moieties.9 This
I
II
B
B
Mes2
Mes2
B
B
Mes2
Mes2
III
IV
Figure 1. Selected examples of known large-bite diboranes.
To begin, 1,8-dibromoanthracene was targeted as the building
block for further functionalisation, which could be synthesised
in two steps in accordance with previously established
literature methods.12 From this point, both mono- and bi-
functionalised anthracene derivatives 1 and 2 could be readily
synthesised through functionalisation of one or both sites
through lithiation and quenching with dimesitylboron fluoride
in the necessary stoichiometries (Scheme 1). These compounds
could be readily characterised by multinuclear NMR
spectroscopy with the prevailing 11B resonance appearing for
both 1 and 2 as a broad singlet centred at δ ≈ 75 ppm as usually
a. Department of Chemistry, Texas A&M University, College Station, Texas 77843-
3255, United State
b. Department of Chemistry, Faculty of Science, Chulalongkorn University, Phayathai
Road, Bangkok, 10330, Thailand.
† Footnotes relating to the title and/or authors should appear here.
Electronic Supplementary Information (ESI) available See DOI: 10.1039/x0xx00000x
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 2 of 7
COMMUNICATION
Journal Name
observed for such triarylboranes.8a, b, 10 Additionally the 1H NMR Most triarylboranes are electroactive and undVeierwgoArticale Oonnliene-
spectrum of 1 features resonances at δ = 2.00 (12H) and 2.31 electron reduction corresponding to the DfoOrIm: 10a.t1i0o3n9/oCf9aDTb0o3r2o38nJ-
(6H) ppm for the methyl groups of the mesityl moiety, with the centred radical.14 A prototypical example of such a behaviour is
aryl mesityl protons appearing at δ = 6.80 (4H) ppm. Similar displayed by Mes3B which is reduced at -2.73 V vs Fc+/Fc in
shifts are observed for 2 (δ = 1.83 (24H), 2.27 (12H) and 6.70 THF.15 In the case of diboranes such as III and IV, two distinct
(8H) ppm however, the ortho-Me and meta-H groups show waves are observed in line with the successive reduction of the
extensive line broadening as a result of restricted rotation about two boron centers.10 We note in passing that a related
the juxtaposed boranes which is evident in the solid-state. behaviour is observed for 9,10-bis(dimesitylboryl)anthracene
Solid-state structures of both 1 and 2 could be measured using which is cleanly reduced into an isolable dianion.11b The cyclic
X-ray diffraction which confirmed the expected formulation voltammograms of 1 and 2 show a much more complicated
(Figure 2). 1, which crystallises in the C2/c space group, adopts behaviour characterised by the absence of reversible processes.
a propeller configuration as expected with angles about the The first reduction wave appears at E1/2 -2.23 V and -2.31 V for
central boron atom measuring between 116.1(3) and 122.5(3)° 1 and 2, respectively. The potential measured for both
in a trigonal planar geometry. In the solid-state, 2 also compounds are close to one another which may appears
crystallises in the C2/c space group with half of the molecule in surprising at first but which is consistent the fact that calculated
the asymmetric unit. There is slightly more variation in the bond LUMO energies are also virtually identical, differing by only 0.05
angles about the boron centre, between 114.8(2) and 123.9(2)° ev. For both compounds, the first reduction wave is quasi-
with the interstitial separation between the two boron atoms reversible; it also appears at a potential that is substantially
measuring 5.576(4) Å. This boron-boron separation is close to more anodic than that of simple triaryl boranes and close to the
that observed in the triptycene-based system IV (5.559(4) Å).
redox potential of simple anthracene derivatives.16 Hence, we
assigned this first reduction to an anthracene-based process.
This assignment is consistent with the LUMO of these
derivatives which shows extensive participation of the
backbone, with a contribution from the boron atoms. Scanning
to more negative potentials indicates several subsequent
irreversible processes that have not been assigned. The UV-vis
spectrum of compound 1 displays two main low energy bands.
The first one, centred at 328 nm is reminiscent of that observed
for simple triaryl boranes such as trimesityl borane17 and is thus
assigned to the boron centred chromophore, with the main
transition having ligand-to-element-charge-transfer character.
The second band centred at 407 nm shows three vibronic
features that closely resemble the 0-0, 0-1 and 0-2 vibronic
bands of anthracene both in terms of respective intensity and
energy spacing (1203-1624 cm-1 vs. 1478 cm-1 for anthracene).
On this basis, this band is assigned to the S0→S1 transition of the
anthryl chromophore which has -to-* character. However,
the energy of this band is redshifted with respect to that of
anthracene. This redshift can be quantitatively analysed based
on the 0-0 vibronic band which is centred at 407 nm in 1 vs 378
nm in anthracene. We rationalise this 1885 cm-1 redshift is due
to the presence of the boron atom, the empty p-orbital of which
conjugates with the * of the anthryl group, lowering its energy.
The spectrum of 2 again features a low energy band whose
vibronic features are less distinct but suggests an assignment to
the S0→S1 transition of the anthryl chromophore. This band is
further redshifted with respect to that of the pure hydrocarbon
(419 nm (2) vs 378 nm (anthracene)), as could be expected with
additional p-* conjugation arising from the presence of a
second chromophore. The features observed at higher energy,
past 370 nm, are less readily assignable than in the case of 1 but
probably involve the boron-centred chromophores.
Cl
O
Cl
BMes2
(c)
1
(44%)
O
(a)
Br
O
Br
Br
Br
BMes2
BMes2
(b)
(d)
O
2
(40%)
67%
64%
Scheme 1. Synthetic overview for mono- and bis-boranes 1 and 2 adapted in part from
literature methods.12-13 (a) KBr (4.5 equiv.), CuCl2 (0.1 equiv.), H3PO4/PhNO2 (1:4), reflux,
2 d; (b) Al(OiPr)3 (7 equiv.), cyclohexanol, reflux, 3 d; (c) n-butyllithium (2 equiv.), TMEDA
(2.5 equiv.), THF, Mes2BF (1 equiv.) 18 h; (d) n-butyllithium (2 equiv.), TMEDA (2.5 equiv.)
THF, Mes2BF (2 equiv.), 18 h.
Time dependent density functional theory (TD-DFT)
calculations reinforce the posited transitions outlined above
whereby a dominant vertical excitation at 416 nm and 421 nm
is noted for 1 and 2 respectively, which satisfactorily coincide
with those observed experimentally for the 0-0 transitions at
Figure 2. Solid-state structures of 1 (top) and 2 (bottom). Hydrogen atoms omitted for
clarity. Thermal ellipsoids drawn at 50%.
2 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 3 of 7
Dalton Transactions
Please do not adjust margins
Journal Name
COMMUNICATION
406 nm (1) and 419 nm (2). The in silico results also reinforce magnitude less effective at cyanide complexation with a binding
View Article Online
the proposed -to-* (HOMO→LUMO) transition of the anthryl constant of K (CN–) = 9 x 105 M–1 (see supporting information).
DOI: 10.1039/C9DT03238J
unit which is perturbed by the appended boron atoms, as seen This may be as a result of steric crowding about the boron
by the mixing of the vacant p-orbital on boron and the centre precluding effective binding of larger diatomics. The
anthracene -system, comprising the LUMO. These TD-DFT similarity of the spectra obtained with fluoride and cyanide
calculations also suggest that the band at higher energy indicates that the cyanide anion in [2-CN]- is not bridging the
(calculated: 344 nm for 1 and 351 nm for 2, observed: 325 nm two boron centers. Bearing in mind that a bridging cyanide
for 1 and 332 nm for 2) correspond to the HOMO-1→LUMO anion was observed in the case of [III-CN]- and [IV-CN]-,10b we
transitions which involves charge-transfer from the mesityl propose that C-H unit at the 9 position of the anthracenediyl
groups to the borylated anthracene moiety (Figure 3).
backbone of 2 hinders this binding mode.
LUMO
-1.104 eV
LUMO
-1.156 eV
HOMO
-6.360 eV
HOMO
-6.381 eV
HOMO-1
-7.249 eV
HOMO-1
-7.348 eV
Figure 4. Changes in UV-vis. absorbance spectra and cyanide binding isotherms of 1 (left)
and 2 (right) upon titration with TBAF. Conducted at a concentration of 60 μM in THF.
Isotherms measured at λmax = 388 nm (1) and 398 nm (2).
Figure 3. Depiction of LUMO, HOMO and HOMO-1 molecular orbitals of 1 (left) and 2
(right). Isosurface value = 0.03.
Again, mass spectrometry supports a similar 1:1 binding mode
with the parent ion [2-CN]– being detected at m/z = 700.4300
(calc. = 700.4291). It is also noteworthy that upon fluoride or
cyanide binding to the monofunctionalised derivative 1, the
resulting UV-vis. spectra closely resemble that of the native
unfunctionalised anthracene backbone, confirming population
of the vacant boron p-orbital by donation of an electron pair
from the incoming anion. This effect is also readily detectable
with the naked eye, with a distinct blue shift of the colour from
deep yellow to light yellow upon conversion from 1 to [1-F]-.
This is also supported by theoretical studies showing how
addition of fluoride to 1 removes the borane from the
conjugated system producing essentially idealised frontier
molecular orbitals on anthracene (Figure 5). By contrast,
conversion of 2 into [2-F]– leads to the appearance of a red-
shifted absorption band. This band is assigned to an anthracene
-to-borane charge transfer band, as supported by the fact that
the HOMO of the anionic complex has dominant anthracene
character while the LUMO shows high boron p-orbital character
(Figure 5). The spectral changes observed upon cyanide
complexation are proposed to have the same origin.
Building on the seminal work carried out on tris(9-
anthryl)borane as a fluoride receptor,18 the photophysical
responses of 1 and 2 to fluoride were investigated via UV-vis.
titration studies. Incremental addition of a TBAF solution to 1 in
CH2Cl2 shows uniform conversion to a new absorbance
spectrum (Figure 4). The titration data could be fitted to a 1:1
binding isotherm in both cases which is consistent with NMR
spectroscopic evidence of a 1:1 binding mode. Equilibrium
constants could be extracted from these data which were
determined as K (F–) = 7 x 106 M–1 for 1 and 4 x 106 M–1 for 2.
This binding mode was further verified via mass spectrometry,
particularly for 2, whereby a signal was detected at m/z =
693.4249 (calc. = 693.4245) for the parent ion of [2-F]–with the
corresponding m/z signal at 356.2117 for the bis-functionalised
[2-F2]2– not being detected. With this encouraging information
to hand, attention was shifted to the cyanide anion to observe
as to whether diatomics could also be captured by these
systems. In a similar process, addition of increasing equivalents
of TBACN in THF led to a new absorbance profile in the UV-vis.
spectrum for the posited complexes [1-CN]- and [2-CN]- closely
resembling that of the fluoride adducts. Extracting equilibrium
constants from these data established that 1 is particularly
potent in cyanide binding with K (CN–) = 3 x 107 M–1.
Interestingly, the bifunctional derivative 2 was over an order of
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 3
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 4 of 7
COMMUNICATION
Journal Name
The mono- and bis-functionalised anthracene deriVviaewtiAvreticsle1Oanlninde
DOI: 10.1039/C9DT03238J
2 have been synthesised. UV-vis studies into these compounds
reveal how progressive depletion of electron density of the
anthracene backbone results in a red-shift of the 
transition. This is achieved by virtue of increasing p-
 conjugation through the addition of one or two boryl units.
These findings are supported by theoretical calculations using
TD-DFT methods which confirm the HOMO-LUMO excitation of
the anthracene  to  transition which is perturbed by the
inclusion of the Lewis acidic boron atoms. Anion responses of 1
and 2 show the affinity of the monofunctionalised species
toward both fluoride and cyanide. Interestingly, steric crowding
in 2 results in lower affinity for the diatomic cyanide anion.
Subsequent fluorescence studies outline some interesting
differences in the emission profiles of 1 and 2. Whereas a blue-
shift in the emission spectrum of 1 is observed upon fluoride
association, that of 2 displays an unexpected red-shift resulting
from an electron-rich anthracene -to-borane charge transfer
excited state.
Figure 5. Depiction of frontier molecular orbitals of [1-F]– (left) and [2-F]– (right).
Isosurface value = 0.03.
TD-DFT studies corroborate these findings with a dominant
vertical excitation being noted at 383 nm for [1-F]– which is in
approximate agreement with the 0-0 -to- transition
observed experimentally at 399 nm. Similarly, [2-F]– shows a
theoretical excitation from TD-DFT calculations at 446 nm for
the anthracene -to-borane charge transfer band with the
experimental data giving a broad absorbance band centred at
435 nm.
Experimental
General considerations
All reactions and manipulations were carried out under an atmosphere
of dry, O2-free nitrogen using standard double-manifold techniques
with a rotary oil pump unless otherwise stated. A nitrogen-filled glove
box was used to manipulate solids including the storage of starting
materials, room temperature reactions, product recovery and sample
preparation for analysis. All solvents were dried by passing through an
alumina column (pentane and CH2Cl2) or by refluxing under N2 over
Na/K (Et2O and THF) and stored under a nitrogen atmosphere over 3 Å
molecular sieves. Deuterated solvents were distilled and/or dried over
molecular sieves before use. Chemicals were purchased from
commercial suppliers and used as received. 1,8-dibromo-4a,9a-
dihydroanthracene-9,10-dione and 1,8-dibromoanthracene were
synthesised according to the literature with the spectral analyses being
consistent with literature established values.12 1H, 13C and 11B NMR
spectra were recorded on either a Bruker Avance II 400 or Bruker
Avance 500 spectrometer. Chemical shifts are expressed as parts per
million (ppm, δ) downfield of tetramethylsilane (TMS) and are
referenced to CDCl3 (7.26/77.16 ppm) as internal standards. NMR
spectra were referenced to BF3·Et2O/CDCl3 (11B). The description of
signals includes: s = singlet, d = doublet, t = triplet, m = multiplet and br.
= broad. All coupling constants are absolute values and are expressed in
Hertz (Hz). UV–vis spectra were recorded on a Shimadzu UV-2501PC
utilising a dual halogen/deuterium light source. Mass spectrometry
analyses were performed in-house at the Center for Mass
Spectrometry.
Finally, both 1 and 2 are fluorescent and display quantum yields
(QY) of 0.41 and 0.23, respectively. The small Stokes shift
measured suggest that these compounds emit from the S0-S1
state which can be viewed as an anthracene -* excited state,
perturbed by the trivalent boron atoms. In line with this view,
neutralisation of the unsaturated boron centre by anion
coordination as in [1-F]– and [2-F]–, leads to some drastic
changes. For 1, the emission profile and energy, becomes
almost identical to that of pure anthracene as expected by
removal of the boron-caused disruption. Interestingly, in the
case of 2, a red shift rather than a blue shift is observed (Figure
6). The red shift of this emission is consistent with the red shift
observed in the UV-vis spectrum of 2 upon anion binding.
Accordingly, we assign this emission to an intramolecular
electron-rich anthracene -to-borane charge transfer excited
state, the emission of which falls in the green part of the
spectrum (QY = 0.31). Such a behaviour is reminiscent of that
observed for related bifunctional diboranes upon coordination
of an anion to one of the two boron centers.8b, 19
Synthesis of 1-dimesitylborylanthracene (1)
n-BuLi (2.5 M in hexanes, 0.77 mL, 1.79 mmol, 2 equiv.) was added to a
solution of 1,8-dibromoanthracene (0.3 g, 0.89 mmol, 1 equiv.) and
TMEDA (0.34 mL, 2.23 mmol, 2.5 equiv.) in THF (5 mL) at -78 °C. After
stirring for 1 hour at this temperature, the resulting mixture was treated
with Mes2BF (0.27 g, 1.02 mmol, 1 equiv.) left to warm to room
temperature for 18 hrs. At this time, sat. NH4Cl solution was added to
quench the reaction and the aqueous phase was washed with CH2Cl2 (2
x 5 mL). The organic phases were combined, dried over MgSO4 and
Figure 6. Fluorescence emission spectra of 1 (left) and 2 (right) upon fluoride binding and
their respective colour changes when irradiated with UV light.
Conclusions
4 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 5 of 7
Dalton Transactions
Please do not adjust margins
Journal Name
COMMUNICATION
Cyclic voltammetry
concentrated to a yellow/orange oil. Washing this oil with MeOH (2 x 2
mL) afforded a yellow powder which was crystallised by layering a
saturated CH2Cl2 solution with MeOH. Yield: 169 mg, 0.39 mmol, 44%.
1H NMR (400 MHz, CDCl3, 298 K) δ/ppm: 8.38 (d, JHH = 21.1 Hz, 2H, anth-
H), 8.08 (d, JHH = 8.4 Hz, 1H, anth-H), 7.96 (d, JHH = 8.4 Hz, 1H, anth-H),
7.59 (d, JHH = 8.4 Hz, 1H, anth-H), 7.52 (d, JHH = 6.4 Hz, 1H, anth-H), 7.30–
7.46 (m, 3H, anth-H), 6.80 (s, 4H, Mes-H), 2.31 (s, 6H, p-Me), 2.00 (s,
12H, o-Me). 13C NMR (101 MHz, CDCl3, 298 K) δ/ppm 140.8 (s), 139.1 (s),
134.8 (s), 133.7 (s), 132.4 (s), 131.8 (s), 131.8 (s), 131.5 (s), 129.0 (s),
128.5 (s), 127.9 (s), 127.1 (s), 126.8 (s), 125.5 (s), 125.3 (s), 125.2 (s),
23.3 (s), 21.4 (s). Resonances for carbons bound to boron are not
observed. 11B NMR (128 MHz, CDCl3, 298 K) δ/ppm: 74.9 (br. s). HRMS
(APCI+) m/z calculated for [C32H32B]+: 427.2592, found: 427.2588.
View Article Online
DOI: 10.1039/C9DT03238J
Electrochemical experiments were performed with an electrochemical
analyser from CH Instruments (model 610A) with a glassy-carbon
working electrode and a platinum auxiliary electrode. The reference
electrode was built from a silver wire inserted into a small glass tube
fitted with a porous Vycor frit at the tip and filled with a THF solution
containing tetrabutylammonium hexafluorophosphate (TBAPF6, 0.1 M)
and AgNO3 (5 mM). All three electrodes were immersed in a
deoxygenated THF solution (5 mL) containing TBAPF6 (0.1 M) as a
support electrolyte and the compound to be analysed. Ferrocene was
used as an internal standard and all potentials are reported with respect
to E1/2 of the Fc/Fc+ redox couple. All voltammograms were recorded at
a scan rate of 200 mv/s.
Spectroscopy
Synthesis of 1,8-bis(dimesitylboryl)anthracene (2)
UV-vis. spectrophotometric titrations of
1
and
2
with
n-BuLi (2.5 M in hexanes, 0.77 mL, 1.79 mmol, 2 equiv.) was added to a
solution of 1,8-dibromoanthracene (0.3 g, 0.89 mmol, 1 equiv.) and
TMEDA (0.34 mL, 2.23 mmol, 2.5 equiv.) in THF (5 mL) at -78 °C. After
stirring for 1 hour at this temperature, the resulting mixture was treated
with Mes2BF (0.55 g, 2.05 mmol, 2 equiv.) left to warm to room
temperature for 18 hrs. At this time, sat. NH4Cl solution was added to
quench the reaction and the aqueous phase was washed with CH2Cl2 (2
x 5 mL). The organic phases were combined, dried over MgSO4 and
concentrated to a yellow/orange oil. Washing this oil with MeOH (2 x 2
mL) afforded a yellow powder which was crystallised by layering a
saturated CH2Cl2 solution with MeOH. Yield: 244 mg, 0.36 mmol, 40%.
1H NMR (400 MHz, CDCl3, 298 K) δ/ppm: 8.45 (d, JHH = 14.6 Hz, 2H, anth-
H), 8.05 (d, JHH = 7.4 Hz, 2H, anth-H), 7.30–7.38 (m, 4H, anth-H), 6.70 (s,
8H, Mes-H), 2.27 (s, 12H, p-Me), 1.83 (s, 24H, o-Me). 13C NMR (101
MHz, CD2Cl2, 298 K) δ/ppm: 151.2 (s), 141.8 (s), 139.7 (s), 134.7 (s),
134.1 (s), 132.5 (s), 132.0 (s), 129.1 (s), 128.3 (s), 128.1 (s), 125.7 (s),
23.4 (s), 21.6 (s). 11B NMR (128 MHz, CDCl3, 298 K) δ/ppm: 74.6 (br. s).
HRMS (APCI+) m/z calculated for [C50H53B2]+: 675.4328, found: 675.4333.
tetrabutylammonium fluoride trihydrate and tetrabutylammonium
cyanide were carried out in tetrahydrofuran. 3 mL of a 6 x 10-5 M stock
solution of the borane was prepared and treated with 2 μL aliquots of
the anion at the appropriate concentrations. Fluorescence
measurements were taken on samples in capped quartz cuvettes under
air on a PTI QuantaMaster spectrofluorometer with entrance and exit
slit widths of 2 nm. Quantum yield measurements of 1, 2 and [2-F]– were
referenced against the emission spectra of anthracene in cyclohexane.
Acknowledgments
This work was supported by the Welch Foundation (A-1423), and Texas
A&M University (Arthur E. Martell Chair of Chemistry). R.T. would like
to thank the Development and Promotion of Science and Technology
Talent Projects (DPST) scholarship for support. R. T. acknowledges the
Development and Promotion of Science and Technology (DPST)
program from the Royal Thai Government for financial support.
Conflicts of interest
X-ray crystallography
The crystallographic measurements were performed at 110(2) K using a There are no conflicts to declare.
Bruker APEX-II CCD area detector diffractometer (Mo−Kα radiation, λ =
0.71069 Å). For both 1 and 2, a specimen of suitable size and quality was
Notes and references
1. (a) J. D. Hoefelmeyer, M. Schulte, M. Tschinkl, F. P. Gabbaï,
selected and mounted onto a nylon loop. Semi-empirical absorption
corrections were applied. The structures were solved by direct
methods, which successfully located most of the non-hydrogen atoms.
Subsequent refinement using a difference map on F2 using the
SHELXTL/PC package (version 6.1) allowed location of the remaining
non-hydrogen atoms which were refined anisotropically. H atoms were
added at calculated positions using a riding model.
Coord. Chem. Rev. 2002, 235, 93-103; (b) T. W. Hudnall, C.-W. Chiu,
F. P. Gabbaï, Acc. Chem. Res. 2009, 42, 388-397; (c) E. Galbraith, T.
D. James, Chem. Soc. Rev. 2010, 39, 3831-3842; (d) C. R. Wade, A. E.
J. Broomsgrove, S. Aldridge, F. P. Gabbaï, Chem. Rev. 2010, 110,
3958-3984; (e) K. Bowman-James, A. Bianchi, E. Garcia-Espana,
Editors, Anion Coordination Chemistry. Wiley-VCH Verlag GmbH &
Co. KGaA: 2012; p 559 pp; (f) H. Zhao, L. A. Leamer, F. P. Gabbaï,
Dalton Trans. 2013, 42, 8164-8178; (g) N. Busschaert, C.
Caltagirone, W. Van Rossom, P. A. Gale, Chem. Rev. 2015, 115,
8038-8155; (h) P. A. Gale, E. N. W. Howe, X. Wu, M. J. Spooner,
Coord. Chem. Rev. 2018.
2. (a) L. Schweighauser, H. A. Wegner, Chem. Eur. J. 2016, 22,
14094-14103; (b) J. J. Kiernicki, M. Zeller, N. K. Szymczak, J. Am.
Chem. Soc. 2017, 139, 18194-18197; (c) Y. Su, R. Kinjo, Chem. Soc.
Rev. 2019, 48, 3613-3659; (d) E. von Grotthuss, S. E. Prey, M. Bolte,
H.-W. Lerner, M. Wagner, J. Am. Chem. Soc. 2019, 141, 6082-6091;
(e) A. Lorbach, M. Bolte, H.-W. Lerner, M. Wagner, Chem. Commun.
2010, 46, 3592-3594.
Theoretical
Using the X-ray solid-state structures of complexes
1 and 2,
optimizations of 1, 2, [1-F]– and [2-F]– using DFT methods were
implemented in Gaussian 09 using the M06-2X functional and mixed
basis set F/B: 6-31+G(d’), C/H: 6-31G(d’). Frequency calculations
performed using the same level of theory on the optimised geometries
found no imaginary frequencies. Time-dependent DFT (TD-DFT)
calculations were conducted on the geometry optimised structures
using MPW1PW91 functional and same basis sets as before using a
polarisable continuum model with tetrahydrofuran as the solvent.
This journal is © The Royal Society of Chemistry 20xx
J. Name., 2013, 00, 1-3 | 5
Please do not adjust margins

Please do not adjust margins
Dalton Transactions
Page 6 of 7
COMMUNICATION
Journal Name
3. (a) M. V. Metz, D. J. Schwartz, C. L. Stern, P. N. Nickias, T. J.
Marks, Angew. Chem. Int. Ed. 2000, 39, 1312-1316; (b) V. C.
Williams, G. J. Irvine, W. E. Piers, Z. Li, S. Collins, W. Clegg, M. R. J.
Elsegood, T. B. Marder, Organometallics 2000, 19, 1619-1621; (c) S.
P. Lewis, N. J. Taylor, W. E. Piers, S. Collins, J. Am. Chem. Soc. 2003,
125, 14686-14687; (d) J. Chai, S. P. Lewis, S. Collins, T. J. J. Sciarone,
L. D. Henderson, P. A. Chase, G. J. Irvine, W. E. Piers, M. R. J.
Elsegood, W. Clegg, Organometallics 2007, 26, 5667-5679; (e) L. D.
Henderson, W. E. Piers, J. Organomet. Chem. 2007, 692, 4661-4668;
(f) S. N. Kessler, M. Neuburger, H. A. Wegner, J. Am. Chem. Soc.
2012, 134, 17885-17888; (g) E. von Grotthuss, M. Diefenbach, M.
Bolte, H.-W. Lerner, M. C. Holthausen, M. Wagner, Angew. Chem.
Int. Ed. 2016, 55, 14067-14071; (h) J. W. Taylor, A. McSkimming, C.
F. Guzman, W. H. Harman, J. Am. Chem. Soc. 2017, 139, 11032-
11035.
18. S. Yamaguchi, S. Akiyama, K. Tamao, J. Am. Chem. VSioewc.A2rt0ic0le0O, nline
122, 6335-6336.
DOI: 10.1039/C9DT03238J
19. G. Zhou, M. Baumgarten, K. Müllen, J. Am. Chem. Soc. 2008,
130, 12477-12484.
4. (a) H. E. Katz, J. Org. Chem. 1985, 50, 5027-5032; (b) H. E. Katz, J.
Am. Chem. Soc. 1985, 107, 1420-1421; (c) H. E. Katz,
Organometallics 1987, 6, 1134-1136; (d) M. Reilly, T. Oh,
Tetrahedron Lett. 1994, 35, 7209-7212; (e) S. Solé, F. P. Gabbaï,
Chem. Commun. 2004, 1284-1285; (f) M. Melaïmi, S. Sole, C.-W.
Chiu, H. Wang, F. P. Gabbaï, Inorg. Chem. 2006, 45, 8136-8143; (g)
C. L. Dorsey, P. Jewula, T. W. Hudnall, J. D. Hoefelmeyer, T. J. Taylor,
N. R. Honesty, C.-W. Chiu, M. Schulte, F. P. Gabbaï, Dalton Trans.
2008, 4442-4450; (h) C. Jiang, O. Blacque, H. Berke, Chem. Commun.
2009, 5518-5520; (i) H. Zhao, F. P. Gabbaı̈, Organometallics 2012,
31, 2327-2335.
5. (a) B. Wang, R. Kinjo, Chem. Sci. 2019, 10, 2088-2092; (b) N.
Tsukahara, H. Asakawa, K.-H. Lee, Z. Lin, M. Yamashita, J. Am. Chem.
Soc. 2017, 139, 2593-2596.
6. D. Chen, G. Xu, Q. Zhou, L. W. Chung, W. Tang, J. Am. Chem. Soc.
2017, 139, 9767-9770.
7. H. E. Katz, J. Org. Chem. 1989, 54, 2179-2183.
8. (a) X. Y. Liu, D. R. Bai, S. Wang, Angew. Chem. Int. Ed. 2006, 45,
5475-5478; (b) S.-B. Zhao, P. Wucher, Z. M. Hudson, T. M.
McCormick, X.-Y. Liu, S. Wang, X.-D. Feng, Z.-H. Lu, Organometallics
2008, 27, 6446-6456; (c) C. A. Swamy P, R. N. Priyanka, S.
Mukherjee, P. Thilagar, Eur. J. Inorg. Chem. 2015, 2015, 2338-2344;
(d) C. A. S. P, P. Thilagar, Dalton Trans. 2016, 45, 4688-4696; (e) S.
W. Kwak, H. Kwon, J. H. Lee, H. Hwang, M. Kim, Y. Chung, Y. Kim, K.
M. Lee, M. H. Park, Dalton Trans. 2018, 47, 5310-5317.
9. P. Niermeier, S. Blomeyer, Y. K. J. Bejaoui, J. L. Beckmann, B.
Neumann, H.-G. Stammler, N. W. Mitzel, Angew. Chem. Int. Ed.
2019, 58, 1965-1969.
10. (a) C.-H. Chen, F. P. Gabbaï, Angew. Chem. Int. Ed. 2018, 57,
521-525; (b) C.-H. Chen, F. P. Gabbaï, Chem. Sci. 2018, 9, 6210-6218.
11. (a) K. Liu, R. A. Lalancette, F. Jäkle, J. Am. Chem. Soc. 2019, 141,
7453-7462; (b) Y. Zheng, J. Xiong, Y. Sun, X. Pan, J. Wu, Angew.
Chem. Int. Ed. 2015, 54, 12933-12936.
12. O. Grossman, C. Azerraf, D. Gelman, Organometallics 2006, 25,
375-381.
13. M. W. Haenel, D. Jakubik, C. Krüger, P. Betz, Chem. Ber. 1991,
124, 333-336.
14. Y. Su, R. Kinjo, Coord. Chem. Rev. 2017, 352, 346-378.
15. S. A. Cummings, M. Iimura, C. J. Harlan, R. J. Kwaan, I. V. Trieu, J.
R. Norton, B. M. Bridgewater, F. Jäkle, A. Sundararaman, M. Tilset,
Organometallics 2006, 25, 1565-1568.
16. (a) R. O. Loutfy, R. O. Loutfy, Can. J. Chem. 1976, 54, 1454-1463;
(b) B. Fabre, D. M. Bassani, C.-K. Liang, D. Ray, F. Hui, P. Hapiot, The
Journal of Physical Chemistry C 2011, 115, 14786-14796.
17. J. O. Huh, H. Kim, K. M. Lee, Y. S. Lee, Y. Do, M. H. Lee, Chem.
Commun. 2010, 46, 1138-1140.
6 | J. Name., 2012, 00, 1-3
This journal is © The Royal Society of Chemistry 20xx
Please do not adjust margins

Page 7 of 7
Dalton Transactions
View Article Online
DOI: 10.1039/C9DT03238J
TOC
Mes
Mes
X
BMes2
BMes2
B
BMes2
X-
X = F, CN
1,8- bis(dimesitylboryl)anthracene binds the toxic fluoride and cyanide anion to afford the
corresponding 1:1 complexes that display a red shifted emission in the green pact or the spectrum.