The Energetic Significance of Metallophilic Interactions

Article abstract of DOI:10.1002/anie.201904207

Metallophilic interactions are increasingly recognized as playing an important role in molecular assembly, catalysis, and bio-imaging. However, present knowledge of these interactions is largely derived from solid-state structures and gas-phase computatio

Full text of DOI:10.1002/anie.201904207

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Accepted Article
Title: The Energetic Significance of Metallophilic Interactions
Authors: Qingshu Zheng, Stefan Borsley, Gary S. Nichol, Fernanda
Duarte, and Scott Lee Cockroft
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10.1002/anie.201904207
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RESEARCH ARTICLE
The Energetic Significance of Metallophilic Interactions
Qingshu Zheng,[a] Stefan Borsley,[a] Gary S. Nichol,[a] Fernanda Duarte[a],[b] and Scott L. Cockroft*[a]
Abstract: Metallophilic interactions are increasingly recognized as
playing an important role in molecular assembly, catalysis, and bio-
imaging. However, present knowledge of these interactions is largely
derived from solid-state structures and gas-phase computational
studies rather than quantitative experimental measurements. Here,
we have experimentally quantified the role of aurophilic (AuI···AuI),
platinophilic (PtII···PtII), palladophilic (PdII···PdII) and nickelophilic
(NiII···NiII) interactions in self-association and ligand-exchange
processes. All of these metallophilic interactions were found to be too
weak to be well-expressed in several solvents. Computational energy
decomposition analyses supported the experimental finding that
metallophilic interactions are overall weak, meaning that favorable
dispersion and orbital hybridization contributions from M···M binding
are largely outcompeted by electrostatic or dispersion interactions
involving ligand or solvent molecules. This combined experimental
empty 6s/6p shells of neighboring metal atoms as the origin of
aurophilic and cuprophilic interactions.[3b, 9] At the Hartree-Fock
level, the interaction energy curves are repulsive, and the
aurophilic attraction only appeared when electron correlation is
introduced at the Second-order Møller-Plesset (MP2)
perturbation level of theory.[10] This result therefore suggested
that dispersion is the dominant attractive component of aurophilic
interactions. Subsequently, local MP2 (LMP2) calculations
suggested that dispersion and ionic contributions are equally
important, and that both of these attractive contributions are
dominated by pair-excitations from gold 5d orbitals.[11] In contrast,
dispersion-corrected density-functional theory calculations
suggested that dispersion contributions are much less important
than the earlier MP2 calculations had indicated, and also relatively
independent of the metal.[12] Instead, the prevalence of gold···gold
contacts was attributed to the relativistic enhancement of the
electron affinity of gold, thereby preventing gold from forming ionic
structures involving bridging anions. Similarly, QCISD and
CCSDT approaches also contradict the suggestion from MP2
calculations that metallophilic interactions become more
favorable on descending group 11.[13] Most recently, molecular
orbital analysis and energy decomposition analysis has
suggested that the dimerization of metal complexes arises from a
combination of favorable electrostatic interactions and weakly
covalent metal···metal orbital interactions, which are
counterbalanced by Pauli repulsion.[14]
The theoretical inconsistencies regarding the nature of
metallophilic interactions also extend to estimates of their
strength; calculated gas-phase energies range from negligible at
one extreme,[8b, 8c] to being comparable to hydrogen bonding at
the other (i.e. 0 to 60 kJ mol−1).[1a, 1e, 1f, 12, 15] Indeed, there is very
limited experimental data to support the energetic significance of
metallophilic interactions. For example, molecular balance
approaches examining the energetics associated with
conformational change[16] have been employed to evaluate
aurophilic interactions.[17] However, these balances evaluated
transition state energy barriers rather than equilibrium
conformational free energy differences,[16] meaning that steric
factors also contributed to the determined energies. The self-
association of metal complexes in solution has been used to
experimentally evaluate metallophilic interactions.[18] Most
and computational study provides
a general understanding of
metallophilic interactions and indicates that great care must be taken
to avoid over-attributing the energetic significance of metallophilic
interactions.
Introduction
Metallophilic interactions are often described as occurring in
closed shell (d10, s2) or pseudo-closed shell (d8) metal···metal
contacts.[1] The most well-known and widely reported sub-class of
metallophilic interactions are aurophilic interactions, which occur
between gold atoms.[1e, 1f, 2] Analogous, although less prevalent,
interactions have been reported in other metal-complexes
containing Pd(II), Pt(II), Hg(I), Cu(I) and Ag (I) centers.[1e, 1f, 3]
Such metallophilic interactions have been suggested to be
important for structural control,[4] catalysis,[5] and luminescent and
sensing applications.[4d, 6] Despite their potential applications, the
nature and strength of these interactions are poorly understood.[7]
Previous quantitative investigations of metallophilic
interactions have been largely confined to computational
analyses, which have variously ascribed the origin of aurophilic
interactions to orbital hybridization, dispersion or relativistic
effects.[2-3, 8] Early approaches, employing the Extended Hückel
method, suggested orbital mixing between the filled 5d and the
recently,
a
combined experimental/computational study
employing gas-phase collision-induced dissociation experiments
confirmed a range of 25–30 kJ mol1 for aurophilic interactions,
but the experiments were not amenable to the examination of
neutral dimers or interactions in solution.[19] Indeed, it remains
challenging to isolate the metallophilic contribution to the overall
interaction from other factors, such as the polarizing influences of
charged metal centers, interactions between ligands and solvent
effects.[20] Thus, the obscure origin of metallophilic interactions,
combined with the challenges associated with the evaluation of
their strength encouraged us to undertake a solution-phase
[a]
Dr Q. Zheng, Dr S. Borsley, Dr G. S. Nichol, Prof. S. L. Cockroft
EaStCHEM School of Chemistry
University of Edinburgh
Joseph Black Building, David Brewster Road, Edinburgh EH9 3FJ,
United Kingdom.
E-mail: scott.cockroft@ed.ac.uk
[b]
Prof. Dr F. Duarte, Chemistry Research Laboratory
University of Oxford
12 Mansfield Road, Oxford OX1 3TA, United Kingdom.
Supporting information for this article is given via a link at the end of
the document.
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10.1002/anie.201904207
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RESEARCH ARTICLE
experimental investigation using minimal synthetic complexes
that were amenable to computational analysis.
Here, we have investigated the origin and significance of
metallophilic interactions through a combined experimental and
computational approach. We synthesized a range of complexes
hosting Au(I)···Au(I), Pt(II)···Pt(II), Pd(II)···Pd(II), and Ni(II)···Ni(II)
contacts (Figures 1C and 5A). Self-association and ligand-
exchange experiments were used to estimate the energetic
significance of metallophillic interactions occurring in these
complexes (Figures 1, 2 and 5). The energetic contributions in
both our experimental systems and several previously reported
complexes containing close metal···metal contacts were further
analyzed using empirical and computational energy partitioning
(Figures 2B, 3, 4 and 5), such that general conclusions on the
nature and strength of metallophilic interactions could be drawn.
Results and Discussion
We initiated our study by examining closed shell Au(I)···Au(I)
interactions
using
two
complementary
approaches:
supramolecular self-association[18] (Figure 1A), and ligand-
exchange[20] (Figure 1B). These experimental approaches
facilitated the respective examination of inter- and intramolecular
aurophilic interactions. We reasoned that an ideal model system
for assessing the significance of aurophilic contributions should
be: (i) an overall neutral complex, to minimize ionic forces, (ii) a
gold(I) complex with a closed-shell, d10 electronic configuration,
(iii) a linear or planar structure with small ligands that allow close
contact of the gold centers while minimizing steric effects, (iv)
stable and soluble, to enable solution-phase experiments, (v)
small enough to be subjected to computational analysis using a
range of methods.
Figure 1. Self-association (A) and ligand-exchange (B) approaches for
assessing aurophilic interactions in solution. Yellow spheres represent metals.
Complexes 1–4 (C) are employed in these two approaches.
(Figures S5–S6) nor UV-vis absorption in dichloromethane
(Figure S9) showed any concentration-dependent changes
indicative of self-association over concentration ranges spanning
0.001 mM to 22 mM (solubility limit in acetone). While
intermolecular aurophilic interactions appeared not to be
preserved in solution in this system, we proposed that an
intramolecular approach may instead aid the formation of
metallophilic interactions that would otherwise be too weak to
overcome the entropic penalty associated with intermolecular
association.[16, 23] Thus, we designed U-shaped complexes 3 and
4, where Au···Au contacts are enforced via a bridging ligand
(Figure 1C).[24] The strength of the intramolecular interactions in
these enforced systems may be probed through a ligand-
exchange approach, where the intramolecular interactions
between two gold fragments influence the equilibrium position
(Figure 1B). Complex 4 contains a U-shaped ligand L4 bound to
two identical AuC6F5 moieties (Figure 1C). The Au–N bond in
these complexes is labile and formed under thermodynamic
control, and would be expected to be energetically similar in both
complex 2 and complex 4. Upon mixing ligand L4 with two
equivalents of complex 2, two equilibria describe the ligand
exchange process (Figure 2A). Initially, ligand exchange between
ligand L4 and two equivalents of complex 2 gives rise to complex
4′ while releasing ligand L2 into solution. A subsequent ligand
exchange with another equivalent of complex 2 forms complex 4,
releasing a second molecule of L2 into solution. Analogous
experiments were also performed using ligand L3 and complex 1
in a wide range of solvents (Figure 2B). Due to the slow exchange
of ligands on the NMR timescale, the equilibrium concentrations
of all species could be determined by NMR spectroscopy
Based on the above considerations, complexes 1–4 (Figure
1C) were synthesized (Scheme S1). Single-crystal X-ray
structures of complexes 2–4 showed close Au···Au contacts in
the range of 3.3–3.5 Å (Figures S71–S78). These short Au···Au
contacts are shorter the pairwise sum of the crystallographically
determined van der Waals radii for gold (3.7–4.4 Å),[21] and also
lie within the previously reported range for aurophilic interactions
(2.8–3.5 Å).[9b, 11] However, the non-planar structure of complex 1
hindered the formation of close Au···Au contacts in the solid state.
Nonetheless, complexes 2–4 satisfied our ideal design criteria for
examining aurophilic interactions. The neutral, linear Au(I)
complexes are planar, allowing stacking of the complexes with
close
Au···Au
contacts.
The
electron-withdrawing
pentafluorophenyl group increases the stability of the
complexes.[22] Furthermore, the complexes showed good
solubility in a range of solvents (Table S1), allowing the behavior
1
of the complexes to be studied in solution by H and 19F NMR
spectroscopy.
Initially, the self-association (Figure 1A) of complex 2 was
investigated. However, neither NMR spectroscopy in acetone-d6
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[ ][
]
L
2
4
⁄
1 2 K2 =
(2)
[ ][
2
]
4'
∆G푖 = − RTln퐾푖 i = 1,2
∆∆G = ∆G2 − ∆G1
(3)
(4)
The free energy of the equilibria, G, may thus be obtained using
equation (3). The difference between G2 and G1 (equation (4))
corresponds to the intramolecular interaction energy between the
two identical AuC6F5 moieties (Gexp), i.e. the sum energy of the
aurophilic interactions and the interactions between the
pentafluorophenyl rings (Figure 2B).
Thermodynamic control of the equilibrium populations of
states depicted in Figure 2A was confirmed by the observation of
identical product distributions for both the forward and reverse
ligand-exchange experiments, and with equilibrium being
established in under 5 minutes (Figures S14–S15). The free
energy difference, G1 was determined to be +1.5 ± 1.6 kJ mol−1
in acetone-d6. This small energy difference indicates that the Au–
N coordination bonds in complexes 2 and 4′ are energetically
equivalent. Interestingly, G2 was within error of G1, with a
measured value of +0.4 ± 1.7 kJ mol−1. Therefore, application of
equation (4) gave Gexp = −1.1 ± 2.3 kJ mol−1 in acetone-d6. This
negligible value illustrates an absence of either positive or
negative cooperativity in the second equilibrium shown in Figure
2. Thus, the sum energy of the aurophilic and stacking
interactions between the pentafluorophenyl rings is minor. The
same experimental approach was employed with complex 3,
which possessed better solubility, and little variation was
observed in the determined Gexp values in eleven different
solvents (Figures 2B, S16–S20).
While the determined Gexp values were very small, it
remained possible that the aurophilic interaction was obscured by
electrostatic repulsion between the perfluorinated rings, or other
factors that have not been accounted for. Thus, to gain insight into
these possibilities, a detailed computational analysis of the
system was undertaken. Electrostatic potential surfaces (ESPs)
calculated at the M06/LACVP level confirmed the electron-rich
nature of the perfluorinated rings due to the formal negative
charge on the carbon atom bonded to the gold(I) centers
(Figure S23). We next sought a more quantitative analysis of the
interactions present within our gold···gold complexes by
employing computational energy decomposition analysis (EDA),
which enabled interaction energies to be partitioned into the
electrostatic, dispersion, orbital and Pauli repulsion
components.[26] First, the crystal structure of complex 4 was
computationally modified to remove the phenyl ring bridging
between each half of the complex, yielding dimer 4a (Figure 3A,
top), which provided an intermolecular analogue of complex 4.
Next, dimer 4b (Figure 3A, bottom) was attained by
computationally replacing the two C6F5 moieties in dimer 4a with
hydrogen atoms. EDA calculations were then performed using the
ADF2017.110 package at ZORA-PBE-D3BJ/TZ2P, which
Figure 2. (A) Ligand-exchange experiments between complex 2 and ligand L4
used to examine aurophilic interactions. (B) Experimentally determined free
energies encompassing aurophilic and aromatic stacking interactions (red
dashed lines) between the AuC6F5 moieties (Gexp). 1H NMR spectroscopy
was used to determine the positions of the equilibria forming complexes 4 (light
gray) and 3 (dark gray) at 298K. Experimental errors represent two standard
deviations determined from three repeat measurements.
(Figures S1–S20). Therefore, equilibrium constants K1 and K2
could be determined from equations (1) and (2) respectively,
which account for the statistical factor associated with a 2:1
binding isotherm.[25]
[4'][L ]
2
2K1 =
(1)
[ ]
2 [L ]
4
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indicated under the structures in Figure 3B yielded estimates of
the intermolecular interaction energies of the [C6F5]2 and [L2]2
dimers, and ultimately that of the Au···Au contribution, [Au]2
(Figure 3B, bottom). Applying the same analysis to the imidazole-
derivative 3 (Figure 1) revealed very similar dissected interaction
magnitudes (Figure S29). It should be cautioned that such
dissected energies are only approximate due to limitations of the
partitioning approach.
The replacement of the C6F5 fragments in 4a with hydrides
in 4b (Figures 3A) does not significantly change the partial
charges on the adjacent benzimidazole ligands (Figure S28),
making the dissected intermolecular interaction energy of the
[AuC6F5]2 fragment reasonably reliable. However, the formal
negative charge delocalized over each C6F5 fragment in 4a are
instead localized to the hydride positions in 4b. Thus, the total
electrostatic component of the intermolecular interaction in 4b is
likely to be non-representative of the situation in 4a due to
repulsion between the hydridic positions. The most conservative
means of estimating such an error is to attribute the entire
difference between the electrostatic interaction energies of 4a and
4b as arising from non-transferrable hydridic repulsion, and to
propagate this difference through all dependent dissected
electrostatic and interaction energies (gray and black error bars
in Figure 3, respectively). Even after making such a conservative
error estimate, the total energy of the Au···Au interaction is found
to be small in comparison to the ligand···ligand interactions that
also occur within the dimer complex (Figure 3B, bottom),
[8b, 8c, 28]
Consistent with recent examinations of aurophilic
and
stacking interactions,[29] the energy decomposition analysis
revealed that dispersion is the dominant attractive component in
all of the stacked dimer fragments, but not the [Au]2 dimer.
Instead, the dissection suggests that the main stabilizing forces in
the [Au]2 dimer arise from either electrostatic or orbital
interactions. A favorable contribution from orbital interactions in
aurophilic interactions is further confirmed by deformation plots
generated by the extended transition state method combined with
natural orbitals for chemical valence (ETS-NOCV, also called
EDA-NOCV, Figures S30–S31). The two dominant NOCVs are
both related to the gold centers and contribute about 40% to the
total orbital interactions of dimer 4a, which is in good agreement
with both the empirical fragmentation approach presented in
Figure 3 and previous EDA-based analyses.[30]
Figure 3. Energy decomposition analysis (EDA) results. The overall interaction
energies (hollow black bars) are decomposed into electrostatic (cyan),
dispersion (light blue), orbital (dark blue), and Pauli repulsion (magenta)
components. (A) EDA calculations were performed on dimers 4a, 4b, which are
computationally modified structures generated from the crystal structure of 4.
(B) Fragments dissected from complex 4 and dimers 4a and 4b. See SI section
5.4 for details, where additional fragments are also presented. Computations
were performed using the ADF2017.110 package at ZORA-PBE-D3BJ/TZ2P
level. Error bars estimate the maximum non-transferrable attributable error
arising from the propagation of electrostatic repulsion between the hydrides in
dimer 4b (i.e. the difference between the electrostatic components of E4a and
E4b, indicated by vertical dashed lines in A).
accounts for relativistic effects that are known to be important in
gold chemistry.[8a, 10, 27] The EDA calculations were performed on
dimers 4a and 4b without further optimization to avoid distortion
of the geometries of the dimers (Figure S22).
Having examined the nature of aurophilic interactions in
intramolecular complexes 3 and 4, we sought to extend the
analysis to other systems. The dimer of complex 2 is chemically
identical to dimer 4a, but with an antiparallel head-to-tail
arrangement, rather than parallel head-to-head packing (Figure 4,
top). The alternating red/blue colors of the electrostatic potential
surface scale show that complex 2 is highly polarized, and thus
the head-to-tail, antiparallel stacking is to be expected. Indeed,
EDA analysis of the dimer of complex 2 obtained from the crystal
structure showed that the interaction holding the dimer together is
electrostatically dominated (Figure 4, top right). Significantly,
The overall interaction energy between the monomers in
dimer 4a was calculated as being comparable to a weak hydrogen
bond in the gas phase[23] (black hollow bar in Figure 3, –24.5 kJ
energy. Further EDA partitioning provided an estimate of the
intermolecular interactions in the [AuC6F5]2 fragment (Figure 3B
and Section 5.4 in the SI). Meanwhile, the energy differences
mol−1). The dominant attractive component was determined to be
(Figure 3A, top). In comparison, all interaction components were
diminished in the dimer 4b, which had a negligible total interaction
dispersion, followed by electrostatic and orbital contributions
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Figure 4. Electrostatic potentials (left) and computed energy decomposition analysis (right) determined from the crystal structures of complex 2 and literature
complexes 5, 6, and 7.[22, 31] Electrostatic potential surfaces calculated using M06/LACVP level, and EDA calculations performed using the ADF2017.110 package
at ZORA-PBE-D3BJ/TZ2P level.
electrostatic interactions were also found to dominate the dimeric
packing modes of literature examples of other Au(I) complexes 5,
6, and 7 (Figure 4).[22, 30-31] The dispersion contribution scales
qualitatively with the contact area of the dimers. Interestingly, the
orbital component is the most consistent across all four species,
suggesting that this is a transferrable characteristic of aurophilic
interactions. The dominance of electrostatics across all dimers in
Figure 4 is noteworthy; complexes 3 and 4 also revealed
electrostatically dominated assembly in their extended crystal
packing modes (Figure S23), as do several other related
complexes.[30] Consistent with the importance of electrostatic
interactions in the packing mode, all of these compounds were
only soluble in polar organic solvents (Table S1). The overall
implications are that electrostatic and dispersion contributions are
the dominant factors driving the assembly of most Au(I)
complexes, with a weaker orbital mixing contribution involving the
metal-metal contacts.
to the plane of the complex, preventing oligomerization into chains
and thereby restricting self-association to dimer formation
(Figures 5A and S34). The self-association process in solution
was monitored by 1H NMR spectroscopy, following concentration-
dependent changes in chemical shifts (Figures S35–S39). The
chemical shift changes were fitted to a 1:1 binding isotherm, and
binding energies were determined using equation (3). The G
values obtained were small and ranged between −1 and −5 kJ
mol−1 (Figure 5B), indicating that the intermolecular interactions
between the monomers are not well preserved in solution. Most
significantly, there was no systematic change in the association
energies in relation to the position of the group 10 metal in the
periodic table, further indicating that metallophilic contributions to
the total energy were small.
Energy decomposition analysis of the dimers (based on
computationally modified crystal structures of 8-Pt, Figure 5C and
Figures S40–S41) revealed the dominant role of electrostatics in
dimer formation of complexes 8 and 9, which was consistent with
the earlier results determined for the gold dimers (Figure 4).
Significant dispersion and orbital contributions were also
determined. A minimal change in the dispersion and orbital
contributions was calculated as the metal center was varied, while
the electrostatic component increased from Ni to Pd to Pt. This
increase is offset by a corresponding decrease in the Pauli
repulsion term, resulting in a constant overall interaction energy.
The dispersion term is likely to be dominated by the aromatic
stacking between the planar aromatic ligands and thus does not
change in relation to the metal center. The change in metal affects
the electrostatic component slightly, as reflected in subtle
To explore the generality of our finding that aurophilic
interactions are weak and are not well-expressed in solution, we
extended our investigation to include metallophilic interactions
involving group 10 metals. We designed and synthesized
complexes 8 and 9, which incorporate Pt(II), Pd(II) and Ni(II) metal
centers (Figure 5A), which could be used to examine metallophilic
interactions through a self-association process (Figure 1A). Like
the Au(I) complexes examined above, the Ni(II), Pd(II) and Pt(II)
complexes were overall neutral. A crystal structure of complex 8-
Pt was obtained, showing dimer formation and close
metal···metal contacts in the solid state (Figures S79–S81).
Crucially, the thiol ligand on the metal is orientated orthogonally
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interactions, and a ligand exchange approach to examine
intramolecular interactions. Our experimental results consistently
showed that metallophilic interactions in overall neutral
complexes are too weak to be well-expressed in solution. The
results are supported by computational energy decomposition
analysis of both our own experimental systems, and examples
from the literature. The computational analyses confirm that
metallophilic interactions are indeed weak, and suggest that
weakly favorable orbital hybridization contributions are
a
transferrable characteristic. Our findings in homo-bimetallic
complexes may be compared with those obtained for hetero-
bimetallic complexes, where electrostatics and orbital interactions
were identified as being more important than dispersion in
determining metallophilic contacts in the gas-phase.[15] Indeed,
our experimental results obtained in solution are consistent with
weakly favorable metal···metal contacts being eclipsed by
electrostatic and dispersion interactions involving the surrounding
ligands and solvent.[8c] The importance of electrostatic
interactions and solvent effects in the assembly of metallophilic
complexes is underscored by the prevalence of head-to-tail
crystal packing (e.g. Figure 4),[30] the solubility of complexes
bearing smaller organic ligands being limited to polar organic
solvents (e.g. Table S1), and the (solvophobic) stabilization of
“metallophilic” stacks in the presence of cohesive solvents such
as water and methanol (Table S1).[18, 32] Thus, in view of the other
major energetic contributors, caution must be exercised to avoid
overestimating the significance of metallophilic interactions based
solely on the observation of short metal-metal contacts.
Figure 5. (A) Structures and self-association experiments of complexes 8 and 9
used to examine metallophilic interactions. (B) Experimentally determined free
energies (G) of dimerization, encompassing metallophilic interactions obtained
from concentration-dependent 1H NMR spectroscopy in CDCl3 at 298 K.
Experimental errors represent two standard deviations determined from three
repeat titrations. (C) EDA computation results for complex 8 in which the crystal
structure of 8-Pt was computationally modified (Hex replaced by Me and metal
center varied, Figures S40–S41). EDA calculations performed using the
ADF2017.110 package at the ZORA-PBE-D3BJ/TZ2P level.
Experimental Section
Experimental details including synthetic details, characterization data,
experimental data and analysis, computational details are provided in the
Supporting Information. Single-crystal X-ray structure CCDC deposition
codes: 1894944–1894951.Acknowledgements
variations of the ESP surfaces (Figure S42). As observed for the
gold complexes shown in Figure 4, there is little variance in the
orbital term in Figure 5 as the metal center is varied from Ni to Pd
to Pt in complex 8. EDA-NOCV plots for the complexes containing
the group 10 metals confirmed very small changes in the orbital
energies upon varying the metal (Figures S43–S44). Again, this
suggests that weakly favorable orbital interactions may be a
transferrable general characteristic of metallophilic interactions.
Overall, our combined experimental and computational
investigation provides a consistent indication that metallophilic
interactions are generally weak and therefore overshadowed by
interactions involving the ligands or surrounding solvent
molecules.
We thank Dr Lorna Murray for assistance with NMR spectroscopy,
and the China Scholarship Council for funding to QZ.
Keywords: Metal-metal interactions • Noncovalent interactions •
Metallophilic interactions • Supramolecular chemistry •
Computational chemistry
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In summary, we have presented a combined experimental and
computational investigation into the strength and nature of
metallophilic interactions involving aurophilic (AuI···AuI),
platinophilic (PtII···PtII), palladophilic (PdII···PdII), and nickelophilic
(NiII···NiII) contacts. Specifically, we have employed a self-
assembly approach to study intermolecular metallophilic
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10.1002/anie.201904207
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Entry for the Table of Contents
RESEARCH ARTICLE
Qingshu Zheng, Stefan Borsley, Gary S.
Nichol, Fernanda Duarte and Scott L.
Cockroft*
Page No. – Page No.
Fool’s gold (and silver, nickel,
platinum and palladium)
Metallophilic interactions have been widely implicated in governing a range of
assemblies, despite a limited, and often contradictory understanding. Here, our
combined experimental and computational study provides a general understanding
of the nature of metallophilic interactions, and indicates that great care must be
taken to avoid over-attributing the energetic significance of metallophilic
interactions, particularly in solution.
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