Mechanistic Studies into the Sn/Hg Exchange Reaction of 1,2-Fc(PPh2)(SnMe3) with HgCl2: Competitive Sn-Me over Sn-Fc Cleavage in Noncoordinating Solvents

Article abstract of DOI:10.1021/acs.organomet.8b00862

Tin-mercury exchange represents one of the most versatile and cleanest routes to arylmercuric halides. We found that reaction of the ferrocenylstannane 1,2-Fc(PPh₂)(SnMe₃) (1) with HgCl₂ in acetone results in the unexpected spontaneous formation of 2·HgCl₂, a diferrocenylmercury (Fc₂Hg)-supported diphosphine chelate ligand as its HgCl₂ complex. Mechanistic investigations into the generation of 2·HgCl₂ reveal initial formation of an adduct of 1 with HgCl₂, followed by competitive Sn-Me and Sn-Fc bond cleavage with formation of chloromercury and chlorodimethylstannyl-substituted ferrocene species. When the reaction is performed in chloroform as a noncoordinating solvent, formation of 2·HgCl₂ is not observed, but instead 1,2-Fc(PPh₂)(SnMe₂Cl) (5) is generated as the major product. 5 is initially isolated as a complex with MeHgCl (generated as a byproduct), but the latter can be easily released by heating under high vacuum. When 5 is further reacted with 2 equiv of HgCl₂ in acetone, the adduct 1,2-Fc(PPh₂·HgCl₂)(HgCl) (6·HgCl₂) forms. An X-ray crystal structure of 6·HgCl₂ shows two individual molecules that form Hg···Cl-bridged dimers, which in turn are linked by intermolecular Hg···Cl contacts to give a polymeric structure. In contrast, the equimolar reaction of 5 and HgCl₂ results in initial complexation to give 5·HgCl₂, which slowly transforms into the diferrocenylmercury species 2·HgCl₂. These results confirm that both 1 and the byproduct 5 obtained by Sn-Me bond cleavage are competent intermediates in the formation of complex 2 in acetone. The preferential cleavage of the Sn-Me over the Sn-Fc bond in noncoordinating solvents is attributed to the presence of the diphenylphosphino group in an ortho position. These observations may have broader implications due to the formation of MeHgCl as a highly toxic and volatile byproduct and suggest that noncoordinating solvents are better avoided and extreme caution is necessary when performing Sn/Hg exchange reactions on donor-substituted substrates.

Full text of DOI:10.1021/acs.organomet.8b00862

Article
pubs.acs.org/Organometallics
Cite This: Organometallics XXXX, XXX, XXX−XXX
Mechanistic Studies into the Sn/Hg Exchange Reaction of 1,2-
Fc(PPh2)(SnMe3) with HgCl2: Competitive Sn−Me over Sn−Fc
Cleavage in Noncoordinating Solvents
,†
Alain C. Tagne Kuate,†,‡ Roger A. Lalancette,† and Frieder Jakle*
̈
†Department of Chemistry, Rutgers UniversityNewark, 73 Warren Street, Newark, New Jersey 07102, United States
‡Department of Chemistry, Faculty of Sciences, University of Dschang, P.O. Box 67, Dschang, Cameroon
S
* Supporting Information
ABSTRACT: Tin−mercury exchange represents one of the most
versatile and cleanest routes to arylmercuric halides. We found that
reaction of the ferrocenylstannane 1,2-Fc(PPh2)(SnMe3) (1) with
HgCl2 in acetone results in the unexpected spontaneous formation of
2·HgCl2, a diferrocenylmercury (Fc2Hg)-supported diphosphine
chelate ligand as its HgCl2 complex. Mechanistic investigations
into the generation of 2·HgCl2 reveal initial formation of an adduct
of 1 with HgCl2, followed by competitive Sn−Me and Sn−Fc bond
cleavage with formation of chloromercury and chlorodimethylstann-
yl-substituted ferrocene species. When the reaction is performed in
chloroform as a noncoordinating solvent, formation of 2·HgCl2 is not
observed, but instead 1,2-Fc(PPh2)(SnMe2Cl) (5) is generated as
the major product. 5 is initially isolated as a complex with MeHgCl (generated as a byproduct), but the latter can be easily
released by heating under high vacuum. When 5 is further reacted with 2 equiv of HgCl2 in acetone, the adduct 1,2-Fc(PPh2·
HgCl2)(HgCl) (6·HgCl2) forms. An X-ray crystal structure of 6·HgCl2 shows two individual molecules that form Hg···Cl-
bridged dimers, which in turn are linked by intermolecular Hg···Cl contacts to give a polymeric structure. In contrast, the
equimolar reaction of 5 and HgCl2 results in initial complexation to give 5·HgCl2, which slowly transforms into the
diferrocenylmercury species 2·HgCl2. These results confirm that both 1 and the byproduct 5 obtained by Sn−Me bond cleavage
are competent intermediates in the formation of complex 2 in acetone. The preferential cleavage of the Sn−Me over the Sn−Fc
bond in noncoordinating solvents is attributed to the presence of the diphenylphosphino group in an ortho position. These
observations may have broader implications due to the formation of MeHgCl as a highly toxic and volatile byproduct and
suggest that noncoordinating solvents are better avoided and extreme caution is necessary when performing Sn/Hg exchange
reactions on donor-substituted substrates.
presence of a soft base. For instance, while the synthesis of
diarylmercury compounds can be achieved easily through the
lithium chloride salt elimination reaction (for example in the
synthesis of III and IV),5b,f alternative preparations involve
heating at reflux an acetone solution of the corresponding
arylmercury halide and ammonium thiocyanate, refluxing an
ethanol solution with potassium cyanide, or, in the case of IV·
HgCl2, heating the arylmercury halide in CH2Cl2.5b,f,6 Earlier
work on the symmetrization of arylmercury halide mentions
that the reaction can be achieved using ammonia in
chloroform.7 The arylmercuric halides in turn are frequently
obtained by an Sn−Hg exchange reaction between an
aryltrialkylstannane and HgCl2 in acetone or tetrahydrofuran,
sometimes followed by precipitation of the product by addition
into water.6,8
INTRODUCTION
■
Polyfunctional arylmercuric halides and diarylmercury species
represent an interesting class of Lewis acidic hosts to anions
and neutral guests.1 As a classic example, Hawthorne’s
carboranylmercury macrocycle I (Figure 1) has been shown
to bind anions with unusual coordination geometries.2
Trimeric o-phenylene mercury species II have been widely
explored as building blocks of supramolecular materials.3 Lewis
base functionalized diarylmercury species have also attracted
interest as ambiphilic chelate ligands for metal complexation.
The presence of the Lewis acidic Hg(II) in close proximity to
another metal can give rise to Z-type ligand behavior, where
the Hg atom is able to engage in metallophilic4 interactions.
For instance, short M···Hg contacts have been reported for
complexes of ligands III and IV with various d8 and d10 metal
ions.5
The requisite diarylmercury species are frequently prepared
by reaction of an aryllithium precursor with 0.5 equiv of HgCl2
or, alternatively, by redistribution of arylmercuric halides in the
Received: November 28, 2018
© XXXX American Chemical Society
A
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Figure 2. Comparison of 31P NMR spectra of 1 (a) prior to and (b−
d) after sequential addition of 2 × 0.5 equiv of HgCl2 (acetone) and
(e) isolated 2·HgCl2 (CDCl3). Hg satellites are indicated with
asterisks.
the soluble part revealed the 31P NMR signal for the product
(+26.6 ppm, 22%) and that for the precursor 1, which became
sharp (−16.4 ppm, 38%). The resonance at +32.4 ppm
disappeared and a new broad resonance emerged at −12.8
ppm (40%). Addition of another 0.5 equiv of HgCl2 to the
reaction mixture led to complete disappearance of the 31P
NMR resonance for 1, while a broad resonance reemerged at
+32.3 ppm (33%) and the other resonances at +25.6 ppm (2·
HgCl2, previously at +26.6 ppm, 26%), and −11.3 ppm
(previously at −12.8 ppm, 41%) remained. The presence of
residual starting material in the reaction with 0.5 equiv of
HgCl2 indicates that the HgCl2, once bound to the
diphosphine chelate ligand in the final product 2·HgCl2, is
not readily available for reaction with 1.
Figure 1. Diarylmercury species as hosts for anions and as Z-type
ligands used in the preparation of complexes exhibiting metallophilic
interactions.
We previously reported that stirring a mixture of
ferrocenylstannane 1 (pS isomer) and HgCl2 in acetone over
a period of 1 h9 afforded a yellow precipitate that was
identified as 2·HgCl2 (pS,pS isomer) by single-crystal X-ray
diffraction analysis (Scheme 1).10 The unexpected sponta-
Scheme 1. Formation of 2·HgCl2 via
Mercuriodestannylation10
The observation of 2·HgCl2 immediately after mixing of the
reactants suggests that a fast Sn/Hg exchange reaction takes
place, presumably with initial generation of Me3SnCl and an o-
phosphinoferrocenylmercuric chloride species. One possible
reaction pathway to product 2·HgCl2 (PATH A, Scheme 2)
then involves two successive Sn/Hg exchange reactions where
the second step is favored by intramolecular attack of the
ferrocenylmercury fragment on another ferrocenylstannane
moiety. Another scenario is that the dimer 4 is generated,
which then disproportionates into 2·HgCl2 (PATH B, Scheme
2). Coates et al. described that arylmercury halides rapidly
disproportionate in the presence of tertiary phosphines to give
bis(aryl)mercury and mercury(II) chloride phosphine com-
plexes and that the rate of the disproportion increases with the
dielectric constant of the solvent.11 The authors also proposed
that the first step involves the formation of a salt, on the basis
of the observation that the conductance of a phenylmercuric
chloride solution increases when triphenylphosphine is added.
The latter suggests that triphenylphosphine displaces the
chloride, resulting in the formation of an ionic 1:1 complex.12
Indeed, compound IV·HgCl2 was reported to form by heating
a DCM solution of the arylmercury halide in the absence of
any additives, a process that was reversed in toluene as the
solvent.5f We note, however, that a spontaneous disproportio-
nation of isolated [HgCl(o-C6H4PPh2)]n in DCM into III·
HgCl2 (Figure 1) was not observed but occurred only on
heating in an aqueous−ethanolic solution of potassium
cyanide.5a,b
neous formation of this diarylmercury species prompted us to
further investigate the reaction mechanism with the aim of
identifying possible intermediates or byproducts generated in
the process, as well as gaining a better understanding of the
role of the reaction conditions on the product distribution. We
offer here detailed mechanistic studies into the formation of
this unusual complex.
RESULTS AND DISCUSSION
■
We first examined whether reaction of 1 with a deficiency of
HgCl2 would lead to formation of the free ligand (without
bound HgCl2) or give the complex 2·HgCl2 along with residual
starting material. Thus, an NMR sample was prepared
containing 1 and 0.5 equiv of HgCl2 in acetone-d6 and the
reaction followed by 31P and 1H NMR spectroscopy (Figure 2
and Figures S1−S6). After 30 min, the 31P NMR spectrum
showed a sharp signal with mercury satellites at +27.4 ppm
1
(20%, JHg,P = 4970 Hz) assigned to the product 2·HgCl2,
along with two broad resonances at +32.4 (22%) and −16.0
ppm (58%). The signal at −16.0 ppm matches well with the
chemical shift of the precursor 1, except that it is strongly
broadened. After the sample stood overnight, some precip-
itation occurred, indicative of product formation. Analysis of
A key question arises: what is the identity of the species
associated with the hitherto unassigned signals at +32.4 and
B
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
a
Scheme 2. Possible Pathways in the Formation of 2·HgCl2
a
Acetone solvent coordination to Hg is expected for some of the proposed intermediates but is omitted for clarity. Intermediates with SnMe2Cl in
place of SnMe3 groups can also form due to competing Sn−Me cleavage, as illustrated in Scheme 3.
−11.3 ppm in the 31P NMR spectra of the reaction mixture?
Could they correspond to intermediates along the reaction
path, or are they due to the formation of byproducts?
Evidence for Phosphine−HgCl2 Complex Formation.
The initial formation, disappearance over time, and subsequent
reemergence upon addition of more HgCl2 suggests that the
peak at +32.4 ppm corresponds to a reaction intermediate. It
appears in a chemical shift range which is similar to that of the
final product, indicating the coordination of HgCl2 to a
phosphine moiety. It might therefore correspond to a 1:1 or
2:1 Lewis adduct of 1 and HgCl2 or to a later reaction
intermediate such as 3 or 4 in Scheme 2. The model
compounds FcPPh2·HgCl2 and [(FcPPh2)2·HgCl2] were
synthesized by reaction of FcPPh2 with HgCl2 in a 1:1 and
1:2 ratio in acetone-d6 and structurally characterized by single-
crystal X-ray diffraction analysis after recrystallization from a
CH2Cl2/hexanes mixture (Figure 3). FcPPh2·HgCl2 adopts a
dimeric structure with one terminal and one bridging Cl
substituent for each HgCl2 moiety. The Hg2Cl2 entity is
slightly unsymmetrical with Hg−Cl distances of 2.6051(13)/
2.7298(14) Å (molecule 1) and 2.6596(15)/2.6798(14) Å
(molecule 2); they are significantly longer than those to the
terminal Cl atoms of 2.3961(14) and 2.3772(15) Å. The
terminal Hg−Cl distances of 2.5173(7) and 2.5170(7) Å for
[(FcPPh2)2·HgCl2] are comparatively longer. In contrast, the
Hg−P distances of 2.4069(15) Å (molecule 1) and 2.3941(14)
Figure 3. (a) Molecular structure of one of two independent
Å (molecule 2) for FcPPh2·HgCl2 are shorter than those
molecules of FcPPh2·HgCl2 (50% thermal ellipsoids; hydrogen atoms
found for [(FcPPh2)2·HgCl2] (Hg1−P1 2.5045(7), Hg1−P2
omitted for clarity). Selected bond lengths (Å) and angles (deg):
2.4812(6) Å), indicative of stronger coordination of the
molecule 1, Hg1−Cl1 2.3961(14), Hg1−Cl2 2.6051(13), Hg1−Cl2A
phosphine ligands.
2.7298(14), Hg1−P1 2.4069(15), P1−C1 1.779(6), Hg1···Hg1A
FcPPh2·HgCl2 and [(FcPPh2)2·HgCl2] exhibit 31P NMR
3.935, Hg1−Cl2−Hg1A 95.01(4); molecule 2, Hg2−Cl3 2.3772(15),
resonances at δ +31.5 ppm in CDCl3 (JHgP = 7740 Hz, +31.6
Hg2−Cl4 2.6596(15), Hg2−Cl4A 2.6798(14), Hg2−P2 2.3941(14),
ppm in acetone-d6 at −50 °C) and δ +21.8 ppm (JHgP = 4610
Hz, +20.4 ppm in acetone-d6 at −50 °C), respectively (Table
1). The former is close to the resonance at +32.4 ppm,
providing evidence for the formation of a 1:1 Lewis adduct, 1·
HgCl2, as a reaction intermediate. The complex likely exists as
a dimer, as seen in the X-ray structure of FcPPh2·HgCl2 or
may be stabilized by acetone solvent coordination. The signal
at δ +21.8 ppm for the 2:1 mixture of FcPPh2 and HgCl2 is at a
chemical shift similar to that of 2·HgCl2, consistent with
complexation of HgCl2 by two phosphine ligands. However, a
corresponding species ((1)2·HgCl2) could not be detected in
P2−C23 1.775(6), Hg2···Hg2A 3.938, Hg2−Cl4−Hg2A 95.05(5).
(b) Molecular structure of (FcPPh2)2·HgCl2 (50% thermal ellipsoids;
hydrogen atoms omitted for clarity). Selected bond lengths (Å) and
angles (deg): Hg1−Cl1 2.5173(7), Hg1−Cl2 2.5170(7), Hg1−P1
2.5045(7), Hg1−P2 2.4812(6), P1−C1 1.788(3), P2−C23 1.790(3),
P1−Hg1−P2 116.01(2).
the course of the reaction of 1 and HgCl2. It should be noted
that low-temperature (−60 °C) 31P NMR solution studies of
the related [PPh3·HgCl2] and [(PPh3)2·HgCl2] showed
resonances at δ +33.6 ppm (JHgP = 7670 Hz) and at δ +27.7
C
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Table 1. Comparison of Selected NMR Data for Isolated or in Situ Generated Compounds
compound
solvent, T/°C
δ(119Sn)/ppm
δ(31P)/ppm
δ(1H, Me)/ppm
1
CDCl3, RT
−7.2 (JSn,P = 7.6 Hz)
n.d.
n.d.
−16.2 (nr)
−16.5 (nr)
32.1
28.0 (JHg,P = 5020 Hz)
26.4 (nr)
−15.8
0.21 (Sn−Me, JSn,H = 55 Hz)
0.21 (Sn−Me, JSn,H = 56 Hz)
0.14 (Sn−Me, JSn,H = 56 Hz)
acetone-d6, RT
acetone-d6, −50
CDCl3, RT
acetone-d6, RT
CDCl3, RT
1·HgCl2
2·HgCl2
5
125.9 (JSn,P = 26 Hz)
1.00 (Sn−Me, JSn,H = 61 Hz)
0.53 (Sn−Me, JSn,H = 59 Hz)
0.83 (Sn−Me, br)
acetone-d6, RT
CDCl3, RT
n.d.
112.3
−16.2
−10.9
5·MeHgCl
1.15 (Hg-Me, JHg,H = 198 Hz)
0.79 (Sn−Me, br)
acetone-d6, −50
acetone-d6, RT
n.d.
n.d.
n.d.
34.3 (br)
0.96 (Hg-Me, nr)
0.66 (Sn−Me, br)
0.98 (Hg-Me, JHg,H = 211 Hz)
0.79 (Sn−Me, JSn,H = 63 Hz)
0.63 (JSn,H = 73 Hz)
−13.8
5·HgCl2
6·HgCl2
FcPPh2·HgCl2
acetone-d6, −50
acetone-d6, RT
CDCl3, RT
acetone-d6, RT
acetone-d6, −50
CDCl3, RT
30.1 (JHg,P = 7560 Hz)
35.3 (JHg,P = 7560 Hz)
31.5 (JHg,P = 7740 Hz)
33.5 (nr)
31.6 (nr)
(FcPPh2)2·HgCl2
21.8 (JHg,P = 4610 Hz)
25.0 (JHg,P = 2190 Hz)
20.4 (JHg,P = 4560 Hz)
acetone-d6, RT
acetone-d6, −50
Scheme 3. Formation of 5 and MeHgCl in CDCl3
ppm (JHgP = 4766 Hz), respectively, which corroborate those
found for FcPPh2·HgCl2 and [(FcPPh2)2·HgCl2] above.13
Competitive Sn−Me Bond Cleavage with Formation
of Phosphinoferrocenyl Chlorodimethylstannane 5.
The broad signal at −11.3 ppm in the 31P NMR spectrum of
the reaction mixture (Figure 2) could be assigned to a
byproduct that results from competitive Sn−Me abstraction,
which produces the phosphinoferrocenyl chlorodimethylstan-
nane 5 and methylmercury(II) chloride. The product, 5·
MeHgCl, was isolated after removal of solid 2·HgCl2 by
filtration and purified by repeated crystallization from acetone
at −23 °C. NMR spectroscopic data indicated that the
compound cocrystallizes with methylmercury(II) chloride. A
B(R)Cl). Binding of the Lewis basic substituent to Sn is
believed to weaken the Sn−Me bond trans to the coordinating
group.8e,14 A similar mechanism likely operates here, where
binding of the phosphine moiety itself, or the phosphine-
bound HgCl2, results in weakening of the apical Sn−Me group
in a pentacoordinate Sn intermediate. A plausible intermediate
that may also exist in equilibrium with a Hg2Cl2-bridged
dimeric complex is shown in Scheme 3. The fact that the attack
of HgCl2 at the Sn−Me bond is less favorable in acetone
indicates that, unlike chloroform as a noncoordinating
solvent,15 acetone competes with the phosphine moiety in
the coordination to HgCl2, thereby affecting the reaction
outcome.
Compound 5 was fully characterized by multinuclear NMR
spectroscopy, high-resolution mass spectrometry, and elemen-
tal analysis. In CDCl3, the 31P NMR signal was detected as a
singlet at −15.8 ppm and the 119Sn NMR signal at δ +125.9
ppm appeared as a doublet due to coupling between the 119Sn
and 31P nuclei with JSn,P = 26 Hz (Table 1). A similar signal
splitting but with a lower coupling constant was reported
previously for Fc(PPh2·BH3)(SnMe2Cl)8f (JSn,P = 12.3 Hz). In
acetone-d6, the 31P signal of 5 is only slightly shifted to high
field at δ −16.2 ppm, suggesting that the solvent does not
coordinate to Sn to a significant extent (Figure 4). For the
complex 5·MeHgCl, only a modest upfield shift of the 119Sn
NMR resonance to δ +112.3 ppm and downfield shift of the
31P NMR resonance to δ −10.9 ppm was observed in CDCl3.
Similar data were recorded in acetone-d6 with a 31P NMR shift
1
signal with Hg satellites in the H NMR spectrum in CDCl3
2
(1.15 ppm, JHg,H = 198 Hz) that integrates to 3 protons
confirmed the 1:1 stoichiometry of 5 and MeHgCl (Table 1).
Spectroscopically pure 5 was isolated upon heating the
compound to 90 °C under high vacuum, whereby MeHgCl
is decomplexed and removed by sublimation. Remarkably, 5
and methylmercury(II) chloride became the predominant
products when the reaction between 1 and HgCl2 was
performed in chloroform (Scheme 3 and Figures S7−S10).
The product was once again decomplexed from MeHgCl by
sublimation and 5 isolated as an orange solid in 78% overall
yield.
While not well established in Sn−Hg exchange chemistries,
there is precedent for cleavage of Sn−Me groups in
trimethylstannylferrocenes by boron halides in the presence
of donor substituents in an ortho position (e.g., pyridyl,
D
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(1.80) and Sn (2.17).16 However, this interaction only
modestly influences the geometry, as the Sn atom resides in
a distorted-monocapped-tetrahedral configuration. The extent
of trigonal-bipyramidal character at Sn as judged by the sum of
the equatorial angles of 339.9° is more pronounced than for
10
the trimethylstannyl derivative FcPPh2SnMe3 (∑(equatorial
angles) = 332.2°) but significantly less than for the BH3-
complexed species [Fc(PPh2·BH3)SnMe2Cl] (∑(equatorial
angles) = 349.4°). A much shorter Sn1−Cl1 distance of
2.259(2) Å in comparison to that in [Fc(PPh2·BH3)-
SnMe2Cl]8f (2.4022(9) Å) further indicates that the P1···Sn1
interaction is rather weak.
Figure 4. 31P NMR spectra of 5·MeHgCl in acetone-d6 at room
temperature (RT) and −50 °C in comparison to data for Hg-free 5.
Low-Temperature NMR Studies. In order to further
verify the involvement of complexes [1]n·HgCl2 (n = 1, 2) and
to identify subsequent intermediates along the reaction
pathway, a series of VT NMR experiments were performed.
An NMR sample containing HgCl2 in acetone-d6 was frozen in
liquid nitrogen. Then, a solution of 1 in acetone-d6 was added
on top and immediately frozen. The sample was immersed in
an acetone/dry ice bath for some time and then quickly
introduced into the NMR spectrometer, which was precooled
of δ −13.8 ppm (υ1/2 = 200 Hz). However, when a solution of
5·MeHgCl in acetone-d6 was cooled to −50 °C, the 31P signal
strongly broadened and low field shifted to δ +34.3 ppm (υ1/2
= 1490 Hz), indicating phosphorus coordination to Hg (Figure
4). These observations suggest that the binding equilibrium
between 5 + MeHgCl and 5·MeHgCl is strongly temperature
dependent with little formation of 5·MeHgCl at room
temperature. Importantly, no rearrangement of 5·MeHgCl
into the species 2·HgCl2 was observed in acetone, even after
the solution was kept for several days, which implies that
reaction of 5 with MeHgCl can be ruled out as a pathway to 2·
HgCl2.
1
to −50 °C. The reaction processes were followed by H and
31P NMR while the mixture was gradually warmed to room
temperature (Figure 6 and Figures S11−S19).
The chirality of the pS isomer of 5 was established by
measurement of the optical rotation in chloroform and
calculation of the corresponding specific rotation, which is
determined to be [α]20D = +128 (c 0.1). However, attempts to
obtain single crystals of enantiomerically pure (pS)-5 or (pS)-
5·MeHgCl for X-ray diffraction analysis proved unsuccessful.
In order to assess the molecular structures of these compounds
in the solid state, the synthesis was repeated starting with rac-1,
resulting in isolation of racemic 5 and 5·MeHgCl, respectively,
as orange and yellow crystalline solids. X-ray diffraction data
were collected on single crystals of 5 obtained from CH2Cl2/
hexanes solution by slow evaporation, and the molecular
structure is depicted in Figure 5.
1
Figure 6. 31P (left) and H (right) NMR spectra of [1 + HgCl2] at
−50 °C (bottom) and after warming to RT (top). Tin satellites are
indicated with asterisks and peaks due to residual hexanes with solid
squares.
The P1···Sn1 interatomic distance of 3.8522(12) Å in 5 is
slightly shorter than the sum of the van der Waals radii of P
Immediately after the sample was inserted into the
spectrometer (T = −50 °C), 31P NMR resonances were
observed at δ +36.7 ppm (minor) and at δ +32.1 ppm (major).
As discussed above for the model systems, these signals are in
the typical region of 1:1 complexes of HgCl2 and phosphine.
The signals for the precursor 1 (δ −16.5 ppm in acetone-d6)
and the final product 2·HgCl2 (δ +26.4 ppm in acetone-d6)
were absent, demonstrating that 1 had reacted, but the
formation of the product was not favorable at that temperature.
1
Indeed, the H NMR spectrum at −50 °C exhibited in the
high-field region a singlet at δ 0.13 ppm (JSn,H = 56 Hz)
corresponding to the SnMe3 group, suggesting that the SnMe3
group remained largely unreacted. Minor signals at δ 0.59,
0.61, 0.91, and 1.20 ppm were observed and are tentatively
assigned to formation of small amounts of Me3SnCl, 5,
MeHgCl, and Me2SnCl2. These observations are in line with
formation of the adduct 1·HgCl2 (+32.1 ppm) and a small
amount of a byproduct due to Sn−Me cleavage (+36.7 ppm,
vide infra). When the sample reached ambient temperature,17
the 31P NMR resonances shifted to δ +35.9 and +38.3 ppm but
still remained in the region typical of phosphine adducts of
Figure 5. Molecular structure of 5 (racemate, only one enantiomer
shown). Hydrogen atoms are omitted for clarity. Selected bond
lengths (Å) and angles (deg): Sn1−Cl1 2.259(2), Sn1−C1 2.131(4),
Sn1−C11 2.136(5), Sn1−C12 2.143(5), P1−C2 1.813(5), P1···Sn1
3.8522(12), C1−Sn1−Cl1 100.47(13), C1−Sn1−C11 113.89(19),
C1−Sn1−C12 112.72(19), C11−Sn1−C12 113.3(2), Cl1−Sn1−C11
106.27(17), Cl1−Sn1−C12 109.06(19), P1···Sn1−Cl1 140.93(7),
Sn1−C1−C2−P1 0.3(6).
1
HgCl2. The signal for the SnMe3 group in the H NMR
E
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
spectrum at δ 0.13 ppm had almost completely disappeared.
The signal previously observed at δ 0.59 ppm also disappeared,
while other signals at δ 0.62 (JSn,H = 64 Hz), 0.98, and 1.22
ppm (JSn,H = 86 Hz) gained intensity. The NMR sample was
left standing overnight to give an orange crystalline solid,
which was confirmed to consist of 2·HgCl2. NMR analysis of
the supernatant showed resonances at δ 0.61 (JSn,H = 62/65
Hz, Me3SnCl), 0.97 (JHg,H = 212 Hz, MeHgCl), and 1.17 ppm
(JSn,H = 82/86 Hz, Me2SnCl2), all flanked by easily
distinguishable Sn and Hg satellites. This again strongly
suggests the formation of products arising from Sn−Me
cleavage, especially under kinetic conditions when the reaction
sequence was initiated at low temperature.
Given that the reactivity of the Cp−Sn bond in the
chlorodimethylstannyl species 5 is expected to be lower than in
the trimethylstannyl species 1, making it potentially easier to
detect further intermediates in the Sn−Hg exchange process, a
similar study was performed with racemic 5 and HgCl2
(Scheme 4 and Figures S20−S23). This also allowed us to
The X-ray crystal structure identified the major product as
[Fc(PPh2·HgCl2)(HgCl)] (6·HgCl2). The asymmetric unit
contains two independent molecules, which are connected
through multiple Hg···Cl contacts. The dimerization is
primarily a result of formation of an unsymmetric Hg2Cl2
bridge between the phosphine-bound HgCl2 units with Hg2−
Cl3/Cl5 distances of 2.642(6)/2.965(7) Å and Hg4−Cl5/Cl3
distances of 2.523(7)/2.686(7) Å; these are all relatively
longer than the bonds to the chlorines that are not involved in
the bridge: i.e. Hg2−Cl2 of 2.404(8) Å and Hg4−Cl6 of
2.475(6) Å (Figure 7a). The structure is different from that of
a related arylmercury complex with an acenaphthyl backbone5f
in that an additional weak contact is observed between a HgCl2
chlorine of one molecule and the Fc−Hg−Cl mercury atom of
the other (Cl2···Hg3 3.088(7) Å). A similar contact, Cl5···Hg1
Scheme 4. Reaction of 5 with HgCl2 in Acetone
assess whether the initially formed byproduct 5, while
unreactive toward MeHgCl as indicated by the successful
isolation of 5·MeHgCl, may serve as a reaction intermediate
when additional HgCl2 is present. The 31P NMR spectrum of a
mixture of 5 and HgCl2 in a 1:2 ratio recorded at −50 °C in
acetone-d6 showed a sharp major resonance with mercury
satellites at δ +30.1 ppm (JHg,P = 7560 Hz), which is close to
that of the model complex [FcPPh2·HgCl2] (δ +31.5 ppm in
CDCl3, JHgP = 7740 Hz; + 31.6 ppm in acetone-d6 at −50 °C)
and thus indicates the initial formation of a complex 5·HgCl2
(Table 1). The Sn−Me protons are observed at 0.63 ppm
(JSn,H = 73 Hz) in the 1H NMR spectrum similar to those of 5·
MeHgCl (δ 0.66 ppm in acetone-d6 at −50 °C). When the
temperature was raised to room temperature, Sn/Hg exchange
occurred, and the product then gradually crystallized as an
orange solid. A similar reaction was performed directly at RT,
and 1H and 31P NMR data were collected immediately, prior to
precipitation. The 31P NMR spectrum exhibited a single
resonance at δ +35.3 ppm (JHg,P = 7540 Hz), and the
formation of Me2SnCl2 as a byproduct of the Sn/Hg exchange
was evidenced by a signal at δ 1.23 ppm (JSnH = 82/85 Hz) in
Figure 7. (a) Molecular structure of the dimercury compound 6·
HgCl2 (pS isomer, 50% thermal ellipsoids, hydrogen atoms omitted
for clarity). Selected interatomic distances (Å) and angles (deg):
molecule 1, Hg1−C1 2.06(3), Hg1−Cl1 2.303(7), Hg2−Cl2
2.404(8), Hg2−Cl3 2.642(6), Hg2−P1 2.387(7), P1−C2 1.77(3),
C1−Hg1−Cl1 169.0(8), Cl2−Hg2−Cl3 98.2(2); molecule 2, Hg3−
C23 2.12(3), Hg3−Cl4 2.318(8), Hg4−Cl5 2.523(7), Hg4−Cl6
2.475(6), Hg4−P2 2.420(7), P2−C24 1.77(3), C23−Hg3−Cl4
172.0(8), Cl5−Hg4−Cl6 94.8(2). (b) Illustration of intermolecular
contacts between molecule 1 and molecule 2, which lead to a
polymeric structure. Selected interatomic distances (Å) and angles
(deg): Hg1···Cl5 3.266(7), Hg2···Cl5 2.965(7), Hg3···Cl2 3.088(7),
Hg4···Cl3 2.686(7), Hg2−Cl2···Hg3 83.4(2), Hg2−Cl3···Hg4
89.1(2), Hg2···Cl5−Hg4 85.5(2), Cl1−Hg1···Cl5 85.7(2), Cl2−
Hg2···Cl5 85.7(2), Cl3−Hg2···Cl5 78.6(2), Cl4−Hg3···Cl2 82.2(2),
Cl5−Hg4···Cl3 86.1(2), Cl6−Hg4···Cl3 100.2(2), Hg1···Cl5···Hg2
168.7(3).
1
the H NMR spectrum (Table 1). The isolated pure product
proved insoluble when we attempted to redissolve it in CDCl3
or acetone-d6, preventing 13C NMR analysis, but the product
composition of the mercurated species 6·HgCl2 was verified by
elemental analysis and MALDI-TOF MS, which showed the
expected ion peak for [6]+ (Figure S24).
F
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
3.266(7) Å, leads to extension to a polymeric chain structure in
the crystal lattice (Figure 7b).
especially in CHCl3 as a weakly coordinating solvent (see
Scheme 3), potentially has broader implications due to
formation of highly toxic and volatile MeHgCl. Sn−Hg
exchange reactions are typically assumed to offer facile and
selective access to arylmercury species. Our results suggest that
noncoordinating solvents may be better avoided and extreme
caution is necessary when these transmetalations are performed in
the presence of neighboring donor substituent.
These results demonstrate that, although 5 does not
undergo further reaction with MeHgCl at room temperature,
it readily reacts with HgCl2 via mercuriodestannylation to give
1,2-Fc(PPh2)(HgCl), which is stabilized by complexation to
HgCl2 in the presence of excess HgCl2. When the reaction of 5
with HgCl2 was performed in a 1:1 molar ratio at RT in
acetone, again the adduct 5·HgCl2 was generated initially as
1
the major product according to H and 31P NMR analyses
EXPERIMENTAL SECTION
■
(Figures S25 and S26). The 31P NMR spectrum showed a
broad peak at δ +31.1 ppm, which is close to the chemical
shifts found for the adducts [1 + HgCl2] (δ +32.1 ppm) and [5
+ 2 HgCl2] (δ +30.1 ppm) at low temperature (−50 °C).
However, in contrast to the reaction of 5 with 2 equiv of HgCl2
which ultimately gave 6·HgCl2, upon standing at room
temperature slow conversion of 5·HgCl2 into the dimeric
species 2·HgCl2 was observed (δ(31P) 27.3 ppm, 35% after 24
h, Figures S27 and S28). The latter crystallized from the
reaction mixture, and its structure was confirmed by
verification of the previously reported unit cell parameters10
using X-ray diffraction analysis. Importantly, we found no
evidence for “free” Fc(PPh2)(HgCl) or the formation of its
dimer [Fc(PPh2)(HgCl)]2 (4, Scheme 2) through an
intermolecular Hg−P Lewis acid−base reaction.
General Methods. All reactions were carried out under an
atmosphere of dry nitrogen using high-vacuum Schlenk-line
techniques or an inert-atmosphere glovebox (MBraun). Commer-
cial-grade solvents (toluene, hexanes) were purified by a solvent
purification system from Innovative Technologies, degassed, and
stored over sodium−potassium (NaK) alloy prior to use. Tetrahy-
drofuran was distilled from sodium/benzophenone and dichloro-
methane from CaH2, degassed, and stored under a nitrogen
1
atmosphere. H NMR (499.9/599.7 MHz), 13C NMR (125.7/150.8
MHz), 31P NMR (202.5 MHz), and 119Sn NMR (223.6 MHz) spectra
were recorded on a Bruker Avance III HD NMR spectrometer
(Bruker BioSpin, Billerica, MA) equipped with a 5 mm broad-band
gradient SmartProbe (Bruker, Billerica, MA) or a 600 INOVA NMR
spectrometer (Varian Inc., Palo Alto, CA) equipped with a boron-free
5 mm dual broadband gradient probe (Nalorac, Varian Inc., Martinez,
CA). Chemicals shifts (δ) are given in ppm and were referenced
internally to deuterated solvent signals (CDCl3 7.26 (1H), 77.36 ppm
(13C); C6D6 7.15 (1H), 128.62 ppm (13C); acetone-d6 2.05 ppm
(1H)). Coupling constants (J) are reported in hertz (Hz), splitting
patterns are indicated as s (singlet), d (doublet), pt (pseudo triplet), t
(triplet), br s (broad singlet), nr (nonresolved), and m (multiplet),
and the following abbreviations are used for signal assignments: Ph =
phenyl, Fc = ferrocenyl, Cp = cyclopentadienyl, Me = methyl. Optical
rotation analyses were performed on an Autopol III polarimeter from
Rudolph Research Analytical, using a tungsten−halogen light source
operating at λ 589 nm. High-resolution matrix-assisted laser
desorption ionization-mass spectrometry (MALDI-MS) data were
obtained on an Apex Ultra 7.0 Hybrid FTMS instrument and
MALDI-TOF (time-of-flight) MS data on a Bruker Ultraflextreme
instrument. Elemental analyses were performed by Quantitative
Technologies Inc., Whitehouse, NJ.
Finally, to ascertain that a species akin to the dimer 3 in
PATH A (Scheme 2) is competent as a reaction intermediate,
an excess of 1 (pS isomer) was added to a suspension of
(poorly soluble) 6·HgCl2 (pS isomer) in acetone and the
1
mixture heated to 50 °C for 24 h. Indeed, H and 31P NMR
analysis in CD2Cl2 of the residue after solvent evaporation
indicated the selective formation of 2·HgCl2 (Figures S29 and
S30). It is reasonable to assume then that in the absence of
precipitation of the intermediate, and with the more reactive
trimethylstannyl substituent, rapid conversion of 3 to the
product 2·HgCl2 would occur (Scheme 2). Collectively, these
results offer further support for a mechanism proceeding via
PATH A in the formation of 2·HgCl2 from 1.
Caution! Mercury compounds are highly toxic! Particularly the
exchange reaction between diphenylphosphinoferrocenyl trimethyl-
stannane and mercury(II) chloride generates methylmercury(II)
chloride, which is highly toxic. These reactions have to be handled
with extreme caution, and the use of engineering barriers including
nonpermeable and resistant gloves is essential. Organolithium
reagents and tert-butyllithium in particular are highly reactive and
need to be handled accordingly.
Materials. HgCl2, n-butyllithium (1.6 M in hexanes), and tert-
butyllithium (1.7 M in pentane) were purchased from commercial
sources and used without further purification. The syntheses of the pS
isomer of 110 and the pS,pS isomer of 2·HgCl210 have been previously
reported.
X-ray Diffraction Analysis. Reflections were collected on a
Bruker SMART APEX II CCD diffractometer using Cu Kα (1.54178
Å) radiation. Data processing, Lorentz−polarization, and face-indexed
numerical absorption corrections were performed using SAINT,
APEX, and SADABS computer programs.18 The structures were
solved by direct methods and refined by full-matrix least squares
based on F2 with all reflections using the SHELXTL V6.14 program
package.19 Non-hydrogen atoms were refined with anisotropic
displacement coefficients. All H atoms were found in electron-density
difference maps and treated as idealized contributions. Experimental
details are provided in Table S1 of the Supporting Information.
CCDC 1880976−1880979 contain the supplementary crystallo-
graphic 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
CONCLUSIONS
■
The information gained from 1H and 31P NMR analysis (Table
1) and VT NMR experiments suggests that addition of HgCl2
to (pS)-1 induces coordination of the phosphine moiety to the
mercury atom and the resulting complex (31P NMR, δ +32.4
ppm) undergoes Sn/Hg exchange with cleavage of either a
Sn−Fc or Sn−Me bond to give 2·HgCl2, 5, Me3SnCl, and
MeHgCl. The broad nature of the resonances points to
complex equilibria among 1, [1]·(HgCl2)n (n = 0.5, 1), [1]·
MeHgCl, 5, [5]·(HgCl2)n (n = 0.5, 1), and [5]·MeHgCl. Not
only 1 but also 5 can undergo mercuriodestannylation, as
demonstrated by the isolation of the adduct [Fc(PPh2·
HgCl2)(HgCl)] (6·HgCl2) when 5 was treated with an excess
of HgCl2. The structure of 6·HgCl2 was verified by X-ray
analysis. In the presence of only 1 equiv of HgCl2, 5 initially
formed a HgCl2 adduct, followed by rearrangement into the
dimeric species 2·HgCl2. The fact that we were not able to
isolate the dimeric species 4 leads us to conclude that PATH A
in Scheme 2 presents the more likely mechanism, with 3 as a
plausible intermediate in the formation of 2·HgCl2. This
assessment is further supported by the finding that mixing 6·
HgCl2 with an excess of 1 selectively furnishes 2·HgCl2.
The discovery that donor substituents may promote Sn−Me
over Sn−Fc bond cleavage in Sn−Hg exchange reactions,
G
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ,
UK; fax: + 44 1223 336033.
mixture was allowed to stand overnight. During this period, a yellow
solid precipitate formed, which is typical of the formation of 2·HgCl2.
The solution was left standing for another night, and the yellow
precipitate was then collected by filtration and identified to be 2·
NMR Data for 1 in Acetone-d6. 1H NMR (499.9 MHz, acetone-
d6, 25 °C): δ 7.58 (m, 2H, Ph), 7.44 (m, 3H, Ph), 7.26 (m, 3H, Ph),
3
1
1
7.11 (m, 2H, Ph), 4.55 (pt, JH,H = 2.5 Hz, 1H, Cp), 4.36 (nr, 1H,
HgCl2 by H and 31P NMR NMR in CDCl3. The H and 31P NMR
Cp), 4.02 (s, 5H, free Cp), 3.94 (nr, 1H, Cp), 0.21 (s, 2JSn,H = 56 Hz,
9H, SnMe3). 31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ
−16.5 (s).
data of the supernatant were also recorded. H NMR (499.9 MHz,
1
acetone-d6, 25 °C; only characteristic signals are assigned): δ 0.98 (s,
2
2JHg,H = 211 Hz, MeHgCl), 0.78 (br, Me2SnCl of 5), 0.62 (s, JSn,H
=
64 Hz, Me3SnCl). 31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ
−11.3 (br, 41%), 25.6 (br, 26%, 2·HgCl2), 32.3 (br, 33%). The
solvent was removed from the filtrate under vacuum and the residue
washed several times with hexanes. Recrystallization from acetone at
−23 °C afforded a yellow crystalline solid that was identified to be the
complex 5·MeHgCl according to NMR analysis. Yield: 12.0 mg
(36%). Compound 5 free of MeHgCl was obtained by sublimation of
the latter during heating under high vacuum. Yield: 8.2 mg (36%).
Reaction of 1 with HgCl2 in CDCl3: Synthesis of
Chlorodimethylstannyl Diphenylphosphinoferrocene (5) and
Its MeHgCl Complex. In an NMR tube were mixed CDCl3, 1 (pS
isomer, 0.031 g, 0.058 mmol) and HgCl2 (0.016 g, 0.059 mmol, 1
equiv), and the reaction was followed by 1H and 31P NMR. Data after
60 min standing are as follows. 1H NMR (499.9 MHz, CDCl3, 25 °C;
NMR Data for 2·HgCl2 in Acetone-d6 (Poorly Soluble).
31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ 26.4 (s).
Synthesis of Model Compound [FcPPh2·HgCl2]. To a solution
of HgCl2 (77.2 mg, 0.284 mmol) in acetone (3 mL) was added
dropwise a solution of FcPPh2 (105.2 mg, 0.284 mmol, 1 equiv) in
acetone (3 mL). The mixture was stirred for 1 h, whereupon a yellow
solid precipitate formed that was collected by filtration, washed
several times with hexanes, and dried under vacuum. Yield: 50.0 mg
(27%). The purity of [FcPPh2·HgCl2] (>97%) was established by 1H
NMR and elemental analysis. Crystals for X-ray analysis were
obtained by slow evaporation of a solution of the compound in
CH2Cl2/hexanes at room temperature. 1H NMR (599.7 MHz,
CDCl3, 25 °C): δ 7.79 (m, 4H, Ph), 7.56 (m, 6H, Ph), 4.66 (nr,
4H, Cp), 4.30 (s, 5H, free Cp). 13C{1H} NMR (150.8 MHz, CDCl3,
25 °C): δ 133.9 (d, 3JC,P = 12.4 Hz, o-Ph), 132.8 (s, p-Ph), 129.8 (d,
2
only characteristic signals are assigned): δ 1.14 (s, JHg,H = 200 Hz,
2JC,P = 12.4 Hz, m-Ph), 128.1 (d, 1JC,P = 57.6 Hz, i-Ph), 74.3 (d, JC,P
=
MeHgCl), 0.17 (br s, overlapping Sn−Me signals of 5·MeHgCl and
1). 31P{1H} NMR (202.5 MHz, CDCl3, 25 °C): δ −16.1 (br, 36%, 1),
−11.7 (br, 30%, 5·MeHgCl), 25.9 (br, 6%, 2·HgCl2), 32.5 (br, 28%,
1JHg,P = 5060 Hz, 1·HgCl2). Data after standing for 72 h are as follows.
1H NMR (499.9 MHz, CDCl3, 25 °C; only characteristic signals are
assigned): δ 1.25 (br, Me2SnCl2), 1.15 (s, 2JHg,H = 198 Hz, MeHgCl),
0.88 (br, Me2SnCl of 5·MeHgCl), 0.77 (br, SnMe2 of 5·MeHgCl),
13.7 Hz, Cp), 73.7 (d, JC,P = 9.7 Hz, Cp), 70.9 (s, free Cp), 66.1 (d,
1JC,P = 67.3 Hz, i-Cp-P). 31P{1H} NMR (202.5 MHz, CDCl3, 25 °C):
1
δ 31.5 (s, JHg,P = 7740 Hz). 31P{1H} NMR (202.5 MHz, acetone-d6,
25 °C): δ 33.5 (s). 31P{1H} NMR (202.5 MHz, acetone-d6, − 50 °C):
δ 31.6 (s). High-resolution MALDI-MS (positive mode, anthracene):
12
m/z 607.0118 ([M − Cl]+, calcd for
C
1H1935Cl56Fe200Hg31P
22
2
0.20 (s, JSn,H = 54 Hz, SnMe3 of 1). 31P{1H} NMR (202.5 MHz,
606.9958). Anal. Calcd for C22H19Cl2FeHgP: C, 41.18; H, 2.98.
Found: C, 40.76; H, 3.05.
CDCl3, 25 °C): δ −15.9 (s, 10%, 1), − 5.7 (s, 85%, 5), + 32.5 (br, 5%,
1·HgCl2). A small amount of a precipitate formed throughout this
process. The solvent was removed from the mixture under vacuum
and the residue washed several times with hexanes. Recrystallization
from acetone at −30 °C afforded 5·MeHgCl as a yellow crystalline
solid. Yield: 0.037 g (79%). The purity of 5·MeHgCl (>97%) was
Synthesis of Model Compound [(FcPPh2)2·HgCl2]. To a
solution of HgCl2 (37.4 mg, 0.138 mmol) in acetone (3 mL) was
added dropwise a solution of FcPPh2 (102.1 mg, 0.276 mmol, 2
equiv) in acetone (3 mL). The mixture was stirred for 1 h, whereupon
a yellow solid precipitate formed that was collected by filtration,
washed several times with hexanes, and dried under vacuum. Yield:
90.0 mg (65%). The purity of [(FcPPh2)2·HgCl2] (>90%) was
1
established by H NMR and elemental analysis. Compound 5 was
isolated free of MeHgCl by sublimation of the latter during heating
1
under high vacuum. Overall yield: 0.025 g (78%). The purity of 5
established by H NMR analysis. The bulk material is contaminated
1
(>97%) was established by H NMR and elemental analysis.
by an unidentified byproduct that could not be removed even after
repeated recrystallizations. Crystals for X-ray analysis were obtained
by slow evaporation of a solution of the compound in CH2Cl2/
hexanes. 1H NMR (599.7 MHz, CDCl3, 25 °C): δ 7.69 (br, 8H, Ph),
7.46 (br, 4H, Ph), 7.38 (br, 8H, Ph), 4.42 (br, 4H, Cp), 4.24 (br, 4H,
Cp), 4.14 (s, 10H, free Cp). 13C{1H} NMR (150.8 MHz, CDCl3, 25
°C): δ 133.9 (br, o-Ph), 131.6 (br, p-Ph), 129.2 (br, m-Ph), i-Ph not
observed, 74.0 (nr, Cp), 72.7 (nr, Cp), 70.7 (s, free Cp), 68.2 (br, i-
Data for 5 are as follows. 1H NMR (599.7 MHz, CDCl3, 25 °C): δ
7.58 (m, 2H, Ph), 7.42 (m, 3H, Ph), 7.23 (m, 3H, Ph), 7.10 (m, 2H,
Ph), 4.61 (nr, 1H, Cp), 4.60 (nr, 1H, Cp), 4.13 (nr, 1H, Cp), 4.05 (s,
5H, free Cp), 1.00 (br s, 2JSn,H = 61 Hz, 3H, SnMe), 0.53 (br s, 2JSn,H
1
= 59 Hz, 3H, SnMe). H NMR (499.9 MHz, acetone-d6, 25 °C): δ
7.66 (m, 2H, Ph), 7.49 (m, 3H, Ph), 7.26 (m, 3H, Ph), 7.12 (m, 2H,
3
Ph), 4.70 (pt, JH,H = 2.5 Hz, 1H, Cp), 4.57 (nr, 1H, Cp), 4.21 (nr,
1H, Cp), 4.01 (s, 5H, free Cp), 0.83 (br, 6H, SnMe2Cl). 13C{1H}
NMR (150.8 MHz, CDCl3, 25 °C): δ 140.1 (d, 1JC,P = 6.8 Hz, i-Ph),
137.3 (d, 1JC,P = 6.8 Hz, i-Ph), 135.1 (d, 2JC,P = 20.5 Hz, o-Ph), 132.3
(d, 2JC,P = 16 Hz, o-Ph), 129.9 (s, p-Ph), 128.7 (d, 2JC,P = 8.3 Hz, m-
Cp-P). 31P{1H} NMR (202.5 MHz, CDCl3, 25 °C): δ 21.8 (s, 1JHg,P
=
4610 Hz). 31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ 25.0 (s,
1JHg,P = 2190 Hz). 31P{1H} NMR (202.5 MHz, acetone-d6, −50 °C):
1
δ 20.4 (s, JHg,P = 4560 Hz). High-resolution MALDI-TOF MS
2
(positive mode, DHB): m/z 606.9972 ([M − FcPPh2 − Cl]+, calcd
Ph), 128.6 (d, JC,P = 5.4 Hz, m-Ph), 128.3 (s, p-Ph), 82.6 (s, i-Cp-
1
for
C
1H1935Cl56Fe200Hg31P 606.9958).
12
Sn), 80.9 (d, JC,P = 54 Hz, i-Cp-P), 77.5 (s, Cp), 74.2 (s, JC,Sn = 51
22
Hz, Cp), 74.1 (d, JC,P = 2.7 Hz, Cp), 69.8 (s, free-Cp), 1.8 (d, 2JC,P
=
Sequential Reaction of 1 with Different Amounts of HgCl2
in Acetone. In an NMR tube were mixed acetone-d6, 1 (pS isomer,
22.0 mg, 0.041 mmol), and HgCl2 (6.0 mg, 0.022 mmol, 0.5 equiv),
and the reaction was followed by 1H and 31P NMR. Data after 30 min
9.7 Hz, SnMe), 1.1 (br, SnMe). 31P{1H} NMR (202.5 MHz, CDCl3,
25 °C): δ −15.8 (s). 31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C):
δ −16.2 (s). 119Sn{1H} NMR (223.6 MHz, CDCl3, 25 °C): δ 125.9
(d, JSn,P = 26 Hz). High-resolution MALDI-MS (positive mode,
1
standing are as follows. H NMR (499.9 MHz, acetone-d6, 25 °C;
a n t h r a c e n e ) : m / z 5 5 3 . 9 6 4 4 ( [ M ] + , c a l c d f o r
2
only characteristic signals are assigned): δ 0.98 (s, JHg,H = 211 Hz,
C
1H2435Cl56Fe31P119Sn 553.9669). Anal. Calcd for
12
2
MeHgCl), 0.66 (br s, SnMe2Cl of 5), 0.62 (s, JSn,H = 64 Hz,
24
Me3SnCl), 0.16 (s, 2JSn,H = 56 Hz, Me3Sn of 1). 31P{1H} NMR (202.5
C24H24ClFePSn: C, 52.09; H 4.47. Found: C, 52.16; H, 4.13.
Although these results are slightly outside the range viewed as
establishing analytical purity, they are provided to illustrate the best
values obtained to date.
1
MHz, acetone-d6, 25 °C): δ −16.0 (br, 58%), 27.4 (s, JHg,P = 4970
Hz, 20%, 2·HgCl2), 32.4 (br, 22%). Data after overnight standing are
as follows.1H NMR (499.9 MHz, acetone-d6, 25 °C; only character-
istic signals are assigned): δ 0.98 (s, 2JHg,H = 209 Hz, MeHgCl), 0.79
(br s, SnMe2Cl of 5), 0.63 (s, 2JSn,H = 64 Hz, Me3SnCl), 0.22 (s, 2JSn,H
= 55 Hz, SnMe3 of 1). 31P{1H} NMR (202.5 MHz, acetone-d6, 25
1
Data for 5·MeHgCl are as follows. H NMR (599.7 MHz, CDCl3,
25 °C): δ 7.58 (m, 2H, Ph), 7.44 (m, 3H, Ph), 7.26 (m, 3H, Ph), 7.12
(m, 2H, Ph), 4.65 (nr, 1H, Cp), 4.62 (nr, 1H, Cp), 4.11 (nr, 1H, Cp),
1
2
°C): δ −16.4 (s, 38%, 1), − 12.8 (br, 40%, 5), 26.6 (s, JHg,P = 4960
4.07 (s, 5H, free Cp), 1.15 (s, JHg,H = 198 Hz, 3H, MeHgCl), 0.79
Hz, 22%, 2·HgCl2). Another 0.5 equiv of HgCl2 was added, and the
(br, 6H, SnMe2Cl). 1H NMR (499.9 MHz, acetone-d6, 25 °C): δ 7.67
H
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
1
(m, 2H, Ph), 7.51 (m, 3H, Ph), 7.28 (m, 3H, Ph), 7.13 (m, 2H, Ph),
31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ 35.3 (s, JHg,P
=
3
4.71 (pt, JH,H = 2.0 Hz, 1H, Cp), 4.59 (nr, 1H, Cp), 4.20 (nr, 1H,
7560 Hz). After further standing at RT an orange solid crystallized
out. The crystals were collected and characterized by single-crystal X-
ray diffraction analysis, revealing the formation of the complex 6·
HgCl2. Yield: 5.5 mg (87%). The purity of 6·HgCl2 (>97%) was
established by elemental analysis. High-resolution MALDI-TOF MS
2
Cp), 4.09 (s, 5H, free Cp), 0.98 (s, JHg,H = 211 Hz, 9H, MeHgCl),
2
1
0.79 (br, JSn,H = 63 Hz, SnMe2Cl). H NMR (499.9 MHz, acetone-
d6, − 50 °C): δ 7.80 (m, 2H, Ph), 7.65 (m, 3H, Ph), 7.49 (m, 5H,
Ph), 5.01 (nr, 1H, Cp), 4.77 (nr, 1H, Cp), 4.34 (s, 5H, free Cp), 3.92
(nr, 1H, Cp), 0.96 (s, 9H, MeHgCl), 0.66 (br, SnMe2Cl). 13C{1H}
NMR (150.8 MHz, CDCl3, 25 °C): δ 139.3 (nr, i-Ph), 136.6 (nr, i-
Ph), 135.0 (d, 2JC,P = 19.3 Hz, o-Ph), 132.4 (d, 2JC,P = 16.4 Hz, o-Ph),
130.1 (s, p-Ph), 128.8 (s, p-Ph), 128.7 (d, 3JC,P = 8.1 Hz m-Ph), 128.6
(positive mode, anthracene): m/z 605.9855 ([M − HgCl2]+, calcd for
12
C
1H1835Cl56Fe119Hg31
P 605.9880). Anal. Calcd for
22
C22H18Cl3FeHg2P: C, 30.14; H, 2.07. Found: C, 30.53; H, 2.03.
The product proved to be insoluble in nonpolar or moderately polar
organic solvents, and in DMSO further reactions occurred, leading to
unidentified species.
1
(d, 3JC,P = 6.9 Hz, m-Ph), 81.6 (d, JC,P = 35.7 Hz, i-Cp-Sn), 81.3 (d,
1JC,P = 83.8 Hz, i-Cp-P), 78.0 (d, JC,P = 13.7 Hz, Cp), 74.3 (s, Cp),
74.1 (s, Cp), 69.9 (s, free-Cp), 8.2 (s, MeHgCl), 2.1 (br s, 1JC,Sn = 423
Hz, SnMe2Cl). 31P{1H} NMR (202.5 MHz, CDCl3, 25 °C): δ −10.9
(s). 31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ −13.8 (s).
31P{1H} NMR (202.5 MHz, acetone-d6, −50 °C): δ 34.3 (br).
Reaction of 5 with 1 equiv of HgCl2 in Acetone. A solution of
5 (pS isomer, 21.1 mg, 0.038 mmol) in acetone-d6 (1 mL) was added
to HgCl2 (10.4 mg, 0.038 mmol, 1 equiv). The solution was well
mixed to ensure complete dissolution of HgCl2 and then transferred
to an NMR tube. The H and 31P NMR spectra of the sample were
1
119Sn{1H} NMR (223.6 MHz, CDCl3, 25 °C): δ 112.3 (br s, υ1/2
=
1
recorded after 1/2 h. H NMR (499.9 MHz, acetone-d6, 25 °C; only
125 Hz). Anal. Calcd for C25H27Cl2FeHgPSn: C, 37.32; H, 3.38.
Found: C, 37.47; H, 3.27.
major signals are assigned): δ 7.89 (br m, 2H, Ph), 7.76 (m, 1H, Ph),
7.70 (m, 3H, Ph), 7.66 (br m, 2H, Ph), 7.57 (br m, 2H, Ph), 4.99 (nr,
1H, Cp of 5·HgCl2), 4.87 (nr, 1H, Cp of 5·HgCl2), 4.62 (s, 5H, free
Cp of 5·HgCl2), 4.03 (nr, 1H, Cp of 5·HgCl2), 0.67 (s, 2JSn,H = 71 Hz,
Me2Sn of 5·HgCl2). 31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C):
Reaction of (pS)-1 with 1 equiv of HgCl2 in Acetone-d6
1
followed by VT H and 31P NMR. In an NMR tube were mixed
acetone-d6 (1 mL) and HgCl2 (1.9 mg, 0.0070 mmol), and the
mixture was frozen with liquid nitrogen. Then, a solution of 1 (pS
isomer, 3.7 mg, 0.0069 mmol, 1 equiv) in acetone-d6 (1 mL) was
added on top and immediately frozen. The sample was mixed in an
acetone/dry ice bath and then quickly introduced into an NMR
spectrometer precooled to −50 °C. The reaction was followed by VT
1H and 31P NMR while the sample was gradually warmed to room
1
δ 31.1 (s, JHg,P = 7410 Hz, 5·HgCl2). The sample was kept at room
temperature for 24 h and analyzed again by 1H and 31P NMR.
31P{1H} NMR (202.5 MHz, acetone-d6, 25 °C): δ 30.7 (br s, 1JHg,P
=
5038 Hz, 5·HgCl2, 47%), 27.3 (br s, 2·HgCl2, 35%). After standing for
a few days, a yellow solid crystallized out, which was separated and
dried under vacuum. Determination of the unit cell using X-ray
diffraction analysis unambiguously confirmed the formation of 2·
HgCl2. Yield: 0.015 g (65%).
Reaction of 6·HgCl2 with an Excess of 1. In an NMR tube
containing 6·HgCl2 (11.0 mg, 0.0126 mmol, 1 equiv) was placed an
excess of 1 (8.1 mg, 0.0151 mmol, 1.2 equivs) in acetone-d6 (1 mL).
The mixture was heated at 50 °C for 24 h, whereupon an insoluble
material formed. After the sample was cooled to room temperature,
CH2Cl2 (2 mL) was added, leading to a homogeneous solution. All
volatile components were removed under vacuum, and the residue
was redissolved in CD2Cl2 (0.9 mL) and investigated by NMR,
1
temperature. Data at −50 °C are as follows. H NMR (499.9 MHz,
acetone-d6; only characteristic signals are assigned): δ 1.20 (br,
Me2SnCl2), 0.91 (br, MeHgCl), 0.61 (br, SnMe2Cl of 5), 0.59 (br,
2
Me3SnCl), 0.14 (br, JSn,H = 56 Hz, SnMe3 of 1). 31P{1H} NMR
1
(202.5 MHz, acetone-d6): δ 32.1 (br), 36.7 (br). At −30 °C: H
NMR (499.9 MHz, acetone-d6; only characteristic signals are
assigned): δ 1.23 (br, Me2SnCl2), 0.93 (br, MeHgCl), 0.62 (br,
SnMe2Cl of 5), 0.60 (br, Me3SnCl), 0.14 (br s, 2JSn,H = 56 Hz, SnMe3
of 1). 31P{1H} NMR (202.5 MHz, acetone-d6): δ 33.0 (br), 37.2 (br).
1
Data at −10 °C are as follows. H NMR (499.9 MHz, acetone-d6;
only characteristic signals are assigned): δ 1.23 (br, Me2SnCl2), 0.94
1
revealing the formation of 2·HgCl2. H NMR (599.9 MHz, CD2Cl2,
2
(br, MeHgCl), 0.63 (br, JSn,H = 71.5 Hz, SnMe2Cl of 5), 0.60 (br,
25 °C): δ 7.84 (br m, 4H, Ph), 7.72 (br m, 4H, Ph), 7.60 (br m, 2H,
Ph), 7.45 (br m, 10H, Ph), 4.73 (nr, 2H, Cp), 4.59 (nr, 2H, Cp), 4.30
(nr, 2H, Cp), 3.92 (s, 10H, free Cp). 31P{1H} NMR (202.5 MHz,
CD2Cl2, 25 °C): δ 28.9 (82%, 2·HgCl2), −16.4 (11%, 1). The residue
was then recrystallized from CH2Cl2/decane by partial solvent
evaporation at room temperature to give 2·HgCl2 (12.2 mg, 80%)
as a yellow crystalline solid.
2
2JSn,H = 63.5 Hz, Me3SnCl), 0.15 (br s, JSn,H = 57 Hz, SnMe3 of 1).
31P{1H} NMR (202.5 MHz, acetone-d6): δ 33.7 (br), 36.5 (br). At 25
1
°C: H NMR (499.9 MHz, acetone-d6; only characteristic signals are
2
assigned): δ 1.22 (s, JSn,H = 86 Hz, Me2SnCl2), 0.98 (br, MeHgCl),
0.62 (br, 2JSn,H = 63.5 Hz, Me3SnCl), 0.13 (br s, SnMe3 of 1). 31P{1H}
NMR (202.5 MHz, acetone-d6): δ 35.9 (br), 38.3 (br). After the
sample stood overnight at room temperature, an orange solid
crystallized out, which was confirmed by NMR analysis as 2·HgCl2.
ASSOCIATED CONTENT
* Supporting Information
1
■
The supernatant was also analyzed. H NMR (499.9 MHz, acetone-
2
S
d6; only characteristic signals are assigned): δ 1.18 (s, JSn,H = 87 Hz,
2
2
The Supporting Information is available free of charge on the
ACS Publications website at DOI: 10.1021/acs.organo-
met.8b00862.
Me2SnCl2), 0.97 (s, JHg,H = 213 Hz, MeHgCl), 0.61 (s, JSn,H = 65
Hz, Me3SnCl).
Reaction of (pS)-5 with 2 equiv of HgCl2 in Acetone-d6
1
followed by VT H and 31P NMR: Isolation of HgCl2 Complex
NMR and MS characterization and X-ray crystallo-
graphic data (PDF)
of Chloromercurio Diphenylphosphinoferrocene (6·HgCl2). In
an NMR tube were mixed acetone-d6 (0.1 mL) and HgCl2 (3.9 mg,
0.014 mmol), and the mixture was frozen with liquid nitrogen. Then,
a solution of 5 (pS isomer, 4.0 mg, 0.0072 mmol, 0.5 equiv) in
acetone-d6 (0.1 mL) was added on top and immediately frozen. The
sample was mixed in an acetone/dry ice bath and then quickly
introduced into an NMR spectrometer precooled to −50 °C. Data for
5·HgCl2 are as follows. 1H NMR (499.9 MHz, acetone-d6, −50 °C): δ
4.93 (nr, Cp), 4.87 (nr, Cp), 4.60 (s, free Cp), 3.91 (nr, Cp), 0.63 (s,
2JSn,H = 73 Hz, SnMe2Cl). 31P{1H} NMR (202.5 MHz, acetone-d6, −
50 °C): δ 30.1 (s, 1JHg,P = 7560 Hz). A similar reaction was performed
at RT and NMR data were acquired after 30 min. Data for 6·HgCl2
are as follows. 1H NMR (599.9 MHz, acetone-d6, 25 °C): δ 7.86 (m,
2H, Ph), 7.72−7.62 (m, 8H, Ph), 4.98 (nr, Cp), 4.93 (nr, Cp), 4.71
Accession Codes
CCDC 1880976−1880979 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.
AUTHOR INFORMATION
Corresponding Author
*E-mail for F.J.: fjaekle@rutgers.edu.
■
2
(nr, Cp), 4.52 (s, free Cp), 1.22 (s, JSn,H = 82/85 Hz, Me2SnCl2).
I
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
Z. S.; Matvienko, O. g. V.; Tikhonova, I. A.; Shur, V. B. Coordination
Chemistry of Anticrowns. Isolation of the Chloride Complex of the
Four-Mercury Anticrown {[(o,o’-C6F4C6F4Hg)4]Cl}− from the
Reaction of o,o’-Dilithiooctafluorobiphenyl with HgCl2 and Its
Transformations to the Free Anticrown and the Complexes with o-
Xylene, Acetonitrile, and Acetone. Organometallics 2017, 36, 2437−
2445.
ORCID
Roger A. Lalancette: 0000-0002-3470-532X
Frieder Jakle: 0000-0001-8031-9254
Notes
̈
The authors declare no competing financial interest.
ACKNOWLEDGMENTS
(4) Schmidbaur, H.; Schier, A. Mercurophilic Interactions. Organo-
metallics 2015, 34, 2048−2066.
■
A.C.T.K. thanks the Deutsche Forschungsgemeinschaft (DFG)
for a postdoctoral fellowship. A 500 MHz NMR spectrometer
used in these studies was purchased with support from the
NSF-MRI program (1229030) and Rutgers University. The X-
ray diffractometer was purchased with support from the NSF-
CRIF program (0443538) and Rutgers University (Academic
Excellence Fund).
(5) (a) Bennett, M. A.; Contel, M.; Hockless, D. C. R.; Welling, L. L.
Bis{(2-diphenylphosphino)phenyl}mercury: a novel bidentate ligand
and transfer reagent for the o-C6H4PPh2 group. Chem. Commun.
1998, 2401−2402. (b) Bennett, M. A.; Contel, M.; Hockless, D. C.
R.; Welling, L. L.; Willis, A. C. Bis{(2-diphenylphosphino)phenyl}
mercury: A P-donor ligand and precursor to mixed metal-mercury
(d(8)-d(10)) cyclometalated complexes containing 2-C6H4PPh2.
́
Inorg. Chem. 2002, 41, 844−855. (c) Lopez-de-Luzuriaga, J. M.;
REFERENCES
Monge, M.; Olmos, M. E.; Pascual, D.; Lasanta, T. Amalgamating at
■
the molecular level. A study of the strong closed-shell Au(I)···Hg(II)
interaction. Chem. Commun. 2011, 47, 6795−6797. (d) Lopez-de-
Luzuriaga, J. M.; Monge, M.; Olmos, M. E.; Pascual, D. Experimental
and Theoretical Comparison of the Metallophilicity between d(10)-
d(10) Au-I-Hg-II and d(8)-d(10) Au-III-Hg-II Interactions. Inorg.
(1) (a) Hawthorne, M. F.; Zheng, Z. P. Recognition of electron-
donating guests by carborane-supported multidentate macrocyclic
Lewis acid hosts: Mercuracarborand chemistry. Acc. Chem. Res. 1997,
30, 267−276. (b) Wedge, T. J.; Hawthorne, M. F. Multidentate
carborane-containing Lewis acids and their chemistry: mercuracarbor-
ands. Coord. Chem. Rev. 2003, 240, 111−128. (c) Taylor, T. J.;
Burress, C. N.; Gabbaï, F. P. Lewis acidic behavior of fluorinated
organomercurials. Organometallics 2007, 26, 5252−5263.
́
́
Chem. 2014, 53, 1275−1277. (e) Lopez-de-Luzuriaga, J. M.; Monge,
M.; Olmos, M. E.; Pascual, D. Study of the Nature of Closed-Shell
Hg-II···M-I (M = Cu, Ag, Au) Interactions. Organometallics 2015, 34,
3029−3038. (f) Hupf, E.; Lork, E.; Mebs, S.; Beckmann, J. 6-
Diphenylphosphinoacenaphth-5-yl-mercurials as Ligands for d(10)
Metals. Observation of Closed-Shell Interactions of the Type
Hg(11)···M; M = Hg(II), Ag(I), Au(I). Inorg. Chem. 2015, 54,
1847−1859.
(2) (a) Hawthorne, M. F.; Yang, X. G.; Zheng, Z. P. Host-Guest
Chemistry of Anion-Complexation by Macrocyclic Multidentate
Lewis-Acids. Pure Appl. Chem. 1994, 66, 245−254. (b) Yang, X. G.;
Knobler, C. B.; Zheng, Z. P.; Hawthorne, M. F. Host-Guest
Chemistry of a New Class of Macrocyclic Multidentate Lewis-Acids
Comprised of Carborane-Supported Electrophilic Mercury Centers. J.
Am. Chem. Soc. 1994, 116, 7142−7159. (c) Zheng, Z. P.; Knobler, C.
B.; Hawthorne, M. F. Stereoselective Anion Template Effects -
Syntheses and Molecular-Structures of Tetraphenyl [12]-
Mercuracarborand-4 Complexes of Halide-Ions. J. Am. Chem. Soc.
1995, 117, 5105−5113. (d) Bayer, M. J.; Jalisatgi, S. S.; Smart, B.;
Herzog, A.; Knobler, C. B.; Hawthorne, M. F. B-Octamethyl-
[12]mercuracarborand-4 as host for ″Naked″ fluoride ions. Angew.
Chem., Int. Ed. 2004, 43, 1854−1857.
(6) Tamang, S. R.; Son, J.-H.; Hoefelmeyer, J. D. Preparation of
RHgCl via transmetalation of (8-quinolyl)SnMe3 and redistribution
to R2Hg (R = 8-quinolyl): a highly distorted diorganomercury(II)
with 84 degree C-Hg-C angle. Dalton Trans. 2014, 43, 7139−7145.
(7) (a) Larock, R. C. Organomercury Compounds in Organic Synthesis;
Springer: Berlin, 1985. (b) Jensen, F. R.; Rickborn, B. Ammonia
Symmetrization of Organomercuric Halides. J. Am. Chem. Soc. 1964,
86, 3784−3786.
(8) (a) Taylor, R. Electrophilic aromatic substitution; Wiley:
Chichester, New York, Brisbane, Toronto, Singapore, 1990.
(3) (a) Haneline, M. R.; Tsunoda, M.; Gabbaï, F. P. π-complexation
of biphenyl, naphthalene, and triphenylene to trimeric perfluoro-
ortho-phenylene mercury. Formation of extended binary stacks with
unusual luminescent properties. J. Am. Chem. Soc. 2002, 124, 3737−
3742. (b) Burress, C.; Elbjeirami, C.; Omary, M. A.; Gabbaï, F. P.
Five-order-of-magnitude reduction of the triplet lifetimes of N-
heterocycles by complexation to a trinuclear mercury complex. J. Am.
Chem. Soc. 2005, 127, 12166−12167. (c) Tikhonova, I. A.; Dolgushin,
F. M.; Yakovenko, A. A.; Tugashov, K. I.; Petrovskii, P. V.; Furin, G.
G.; Shur, V. B. Binding of Dienophiles by Macrocyclic Multidentate
Lewis Acids. Synthesis and X-ray Crystal Structure Determination of
Unusual Complexes of Cyclic Trimeric Perfluoro-o-phenylenemer-
cury with p-Benzoquinone and Maleic Anhydride. Organometallics
2005, 24, 3395−3400. (d) Fleischmann, M.; Heindl, C.; Seidl, M.;
Balazs, G.; Virovets, A. V.; Peresypkina, E. V.; Tsunoda, M.; Gabbaï,
F. P.; Scheer, M. Discrete and Extended Supersandwich Structures
Based on Weak Interactions between Phosphorus and Mercury.
Angew. Chem., Int. Ed. 2012, 51, 9918−9921. (e) Fleischmann, M.;
Jones, J. S.; Gabbaï, F. P.; Scheer, M. A comparative study of the
coordination behavior of cyclo-P-5 and cyclo-As-5 ligand complexes
towards the trinuclear Lewis acid complex (perfluoro-ortho-
phenylene)mercury. Chem. Sci. 2015, 6, 132−139. (f) Tugashov, K.
I.; Gribanyov, D. A.; Dolgushin, F. M.; Smol’yakov, A. F.; Peregudov,
A. S.; Tikhonova, I. A.; Shur, V. B. Coordination Chemistry of
Mercury-Containing Anticrowns. Complexation of Perfluoro-o,o’-
biphenylenemercury with o-Xylene and Acetonitrile and the First X-
ray Diffraction Evidence for Its Trimeric Structure. Organometallics
2015, 34, 1530−1537. (g) Tugashov, K. I.; Gribanyov, D. A.;
Dolgushin, F. M.; Smol’yakov, A. F.; Peregudov, A. S.; Klemenkova,
̈
(b) Venkatasubbaiah, K.; Bats, J. W.; Rheingold, A. L.; Jakle, F.
Rational synthesis and complexation behavior of the bidentate Lewis
acid 1,2-bis(chloromercury)ferrocene. Organometallics 2005, 24,
6043−6050. (c) Dorsey, C. L.; Jewula, P.; Hudnall, T. W.;
Hoefelmeyer, J. D.; Taylor, T. J.; Honesty, N. R.; Chiu, C. W.;
Schulte, M.; Gabbaï, F. P. Fluoride ion complexation by a B2/Hg
heteronuclear tridentate Lewis acid. Dalton Trans. 2008, 4442−4450.
(d) Chen, J. W.; Venkatasubbaiah, K.; Pakkirisamy, T.; Doshi, A.;
̈
Yusupov, A.; Patel, Y.; Lalancette, R. A.; Jakle, F. Planar Chiral
Organoborane Lewis Acids Derived from Naphthylferrocene. Chem. -
̈
Eur. J. 2010, 16, 8861−8867. (e) Chen, J. W.; Lalancette, R. A.; Jakle,
F. Stereoselective Ortho Borylation of Pyridylferrocenes. Organo-
metallics 2013, 32, 5843−5851. (f) Tagne Kuate, A. C.; Lalancette, R.
̈
A.; Jakle, F. Planar-chiral ferrocenylphosphine-borane complexes
featuring agostic-type B-H···E (E = Hg, Sn) interactions. Dalton
Trans. 2017, 46, 6253−6264.
(9) When we repeated the synthesis of 2·HgCl2 and stirred the
mixture for a longer period (72 h), the yield of the product only
slightly increased (24%), suggesting that competitive reactions limit
the yield that can be achieved.
̈
(10) Tagne Kuate, A. C.; Lalancette, R. A.; Bannenberg, T.; Jakle, F.
Diferrocenylmercury-Bridged Diphosphine: A Chiral, Ambiphilic, and
Redox-Active Bidentate Ligand. Angew. Chem., Int. Ed. 2018, 57,
6552−6557.
(11) Coates, G. E.; Lauder, A. Complex salts derived from
organomercury halides and related compounds, and their dispro-
portionation. J. Chem. Soc. 1965, 1857−1864.
J
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX

Organometallics
Article
(12) Dessy, R. E.; Budde, W. L.; Woodruff, C. The Formation of
Carbon-Metal Bonds. J. Am. Chem. Soc. 1962, 84, 1172−1178.
(13) Bowmaker, G. A.; Clase, H. J.; Alcock, N. W.; Kessler, J. M.;
Nelson, J. H.; Frye, J. S. Crystal-Structures, Vibrational and 31P NMR-
Studies of Complexes of Tertiary Phosphine-Ligands with Mercury-
(II) Halides. Inorg. Chim. Acta 1993, 210, 107−124.
(14) (a) Gamboa, J. A.; Sundararaman, A.; Kakalis, L.; Lough, A. J.;
̈
Jakle, F. Ferrocene-Based Heteronuclear Bidentate Lewis Acids via
Highly Selective ortho-Borylation of 1,1’-Bis(trimethylstannyl)-
ferrocene. Organometallics 2002, 21, 4169−4181. (b) Boshra, R.;
Sundararaman, A.; Zakharov, L. N.; Incarvito, C. D.; Rheingold, A. L.;
̈
Jakle, F. Binding cooperativity of two different Lewis acid groups at
the edge of ferrocene. Chem. - Eur. J. 2005, 11, 2810−2824.
(15) Diaz-Torres, R.; Alvarez, S. Coordinating ability of anions and
solvents towards transition metals and lanthanides. Dalton Trans.
2011, 40, 10742−10750.
(16) Mantina, M.; Chamberlin, A. C.; Valero, R.; Cramer, C. J.;
Truhlar, D. G. Consistent van der Waals Radii for the Whole Main
Group. J. Phys. Chem. A 2009, 113, 5806−5812.
(17) When the sample was warmed to −30 °C, no significant
changes were observed. Further warming to −10 °C induced
broadening of the 31P NMR resonances but with only small changes
in the chemical shift values (δ +33.7, +36.5 ppm). The proton NMR
spectrum displayed more apparent changes, as the intensity of the
SnMe3 proton signal at δ 0.15 ppm (JSn,H = 57 Hz) decreased,
whereas signals at δ 0.60 (JSn,H = 64 Hz), 0.63 (JSn,H = 72 Hz), 0.94,
and 1.23 ppm gained in intensity.
(18) (a) Bruker SAINT, Version 7.23a; Bruker AXS Inc., Madison,
WI, USA, 2005. (b) Bruker APEX 2, Version 2.0-2; Bruker AXS Inc.,
Madison, WI, USA, 2006. (c) Sheldrick, G. SADABS; University of
̈
̈
Gottingen, Gottingen, Germany, 2008.
(19) (a) Sheldrick, G. M. Acta Crystallogr., Sect. A: Found. Crystallogr.
2008, A64, 112−122. (b) Sheldrick, G. M. SHELXL. Acta Crystallogr.
2015, C71, 3−8.
K
DOI: 10.1021/acs.organomet.8b00862
Organometallics XXXX, XXX, XXX−XXX