Anion-Controlled Positional Switching of a Phenyl Group about the

Award Paper pubs.acs.org/IC

Anion-Controlled Positional Switching of a Phenyl Group about the Dinuclear Core of a AuSb Complex Srobona Sen, Iou-Sheng Ke, and François P. Gabbaï* Department of Chemistry, Texas A&M University, College Station, Texas 77843-3255, United States S Supporting Information *

ABSTRACT: As part of our continuing interest in redox-active, anion-responsive main-group transition-metal platforms, we have investigated the effect of chloride by fluoride anion substitution on the core structure of a dinuclear AuSb platform. Starting from [(o(iPr2P)C6H4)2Cl2SbPh]AuCl (2) in which the antimony-bound phenyl group is positioned trans to the gold atom, we found that the introduction of fluoride anions, as in [(o-(iPr2P)C6H4)2F2SbPh]AuCl (3) and [(o-(iPr2P)C6H4)2ClFSbPh]AuCl (4), produces structures in which the phenyl group switches to a perpendicular direction with respect to the gold atom. Replacement of the goldbound chloride anion in 3 by a fluoride anion can be achieved by successive treatment with TlPF6 and [nBu4N][Ph3SiF2]. These reactions, which proceed via the intermediate zwitterionc gold antimonate complex [o-(iPr2P)C6H4)2F3SbPh]Au (6), trigger migration of the phenyl group to gold and afford [(o(iPr2P)C6H4)2F3Sb]AuPh (7). Because the phenyl group in 7 is orthogonal to that in 3 and opposite to that in 2, the title AuSb platform can be regarded as a molecular analogue of a mechanical three-way switch in which the switching element is a phenyl group. Finally, while all complexes involved retain a Au → Sb interaction, this interaction is no longer present in the zwitterionic derivative 6 because of the neutralization of the Lewis acidity of the antimony center.

■

binding to the antimony atom (Figure 1).11 This chemistry, which takes place in aqueous solvent, demonstrates that,

INTRODUCTION The field of anion recognition is dominated by the design of molecular platforms that respond to the presence of the analyte by a perturbation of their photophysical or electrochemical properties.1 An approach that has gained interest in the past decade is based on the use of Lewis acids, which engage the anion in the formation of a polar covalent interaction as in the case of boron-based sensors.2 After contributing to this area of chemistry extensively,3 our group became interested in the use of antimony(V) Lewis acids for complexation of the potentially toxic fluoride anion.4 Our engagement in this new direction was prompted by the realization that antimony(V) compounds are inherently more Lewis acidic than the corresponding boron(III) compounds.5 This situation is reflected by the greater fluoride-ion affinity of SbF5 versus that of BF36 as well as by the greater resistance of SbF6− to hydrolysis than BF4−.7 Drawing inspiration from the chemistry of B(C6F5)3,8 which is more Lewis acidic6 and yet much more resistant to hydrolysis than BF3, we decided to consider the introduction of organic substituents in antimony(V) compounds as a means to tame the inherent reactive and corrosive nature of antimony pentahalides. Our efforts in this directions were further motivated by a series of reports showing that both neutral and cationic organoantimony(V) species form adducts with neutral and anionic Lewis bases.9 The validity of this approach is illustrated by the anion-binding properties of neutral and cationic antimony(V) derivatives10 such as I and II+, which display a fluorescence turn-on response upon fluoride anion © XXXX American Chemical Society

Figure 1. Fluoride sensors featuring antimony(V).

despite the introduction of organic substituents, the antimony(V) center retains considerable Lewis acidity. With the view of generalizing this phenomenon, we have also tested whether a similar anion-binding behavior could be observed when the antimony center is positioned in the coordination sphere of a transition metal. A first system considered for these studies is the stiboranylplatinum complex III (Figure 2). This complex, which can also be described as a metallostiborane derivative, reacts with aqueous fluoride anions under biphasic conditions to afford the divalent platinum fluorostiborane complex IV. Formation of this complex is the result of a unique internal redox reaction, during which the Pt− Received: June 1, 2016

A

DOI: 10.1021/acs.inorgchem.6b01290 Inorg. Chem. XXXX, XXX, XXX−XXX

Inorganic Chemistry

Award Paper

whose position about the dinuclear core can be precisely controlled by the nature of the halide substituents. As depicted in Figure 4, the three positions adopted by the phenyl group are defined according to three distinct stages (stages 1−3). This paper is organized around each of these three stages.

Figure 2. Fluoride anion binding by III and V. Figure 4. Three positions or stages adopted by the phenyl group about the dinuclear core of the title AuSb platform. The analogy with a mechanical three-way switch is also illustrated.

Sb covalent bond of III is cleaved as a result of fluoride binding to antimony. In addition to changes in the valence of the platinum center, this platform also responds to the presence of the anion colorimetrically. Related results have been obtained with the zwitterionic gold complex V (Figure 2). As in the case of III, the antimony(V) center of this complex is reactive toward fluoride anions, as shown by the rapid conversion of this complex into the corresponding fluorostiborane complex V-F− when in the presence of fluoride anions. In this case, however, the platform shows very minimal structural perturbations, with no notable lengthening to the Au−Sb bond and no major reorganization. The high fluoride-ion affinity displayed by the abovementioned complexes led us to question whether anion complexation would also occur at the antimony center of a triarylstibine transition-metal complex such as VI+, a cationic palladium complex with a Pd−Sb bond supported by two ancillary phosphine ligands (Figure 3).12 Encouraged by a series

■

RESULTS AND DISCUSSION Stage 1. We have previously established that gold complexes of bis- and tris(phosphino)stibine phenylenebridged ligands can be oxidized at antimony without dissociation of the gold atom.15 On the basis of this precedent, we decided to treat the known gold stibine complex 115b with 1 equiv of PhICl2 in tetrahydrofuran (THF). This reaction proceeded smoothly to afford complex [(o-(iPr 2 P)C6H4)2Cl2SbPh]AuCl (2) in 91% yield as a yellow, air-stable derivative (Scheme 1). Scheme 1. Synthesis of 2

The 31P NMR spectrum of complex 2 exhibits a single signal at 103.7 ppm, indicating the symmetric coordination of the phosphorus atoms. The resonance is significantly downfield from the parent complex 1 (69.18 ppm), signaling a more oxidized gold atom.15 The structure of 2 was established by Xray diffraction (Figure 5 and Table 1). The gold center is tetracoordinated with a slightly distorted square-planar coordination geometry, as indicated by the P1−Au−P2 and Sb−Au−Cl1 angles of 166.03(3)° and 160.217(18)°, respectively. The antimony center adopts a distorted octahedral geometry. The short Sb−Cl2 [2.4846(8) Å] and Sb−Cl3 [2.4757(8) Å] bonds are comparable to those observed for other hexavalent antimony species such as (tolyl)2(o(CH2NMe2)C6H4)SbCl2, which features Sb−Cl bonds with an average value of 2.49 Å.16 The antimony and gold atoms are separated by 2.8651(4) Å, which is longer than the distance observed in related gold stiborane complexes such as [(o(Ph2P)C6H4)3Cl2Sb]AuCl [2.7086(9) Å]15c and [(o-(Ph2P)C6H4)2Cl3Sb]AuCl [2.6985(14) Å],15a which have been previously described. The length of the Sb−Au bond in 2

Figure 3. Fluoride anion binding by VI+.

of recent reports that show that coordinated stibines may display Lewis acidic properties,4b,13 we investigated the reaction of VI+ with fluoride anions and observed the formation of the corresponding fluorostiboranylpalladium species. Remarkably, this transformation is accompanied by a change in the denticity of the trisphosphine ligand, leading to a bright-orange trigonalbipyramidal d8 lantern complex (VI-F). The structural reorganization observed upon fluoride binding to complexes such as III and VI+ led us to speculate that anion binding could also be signaled by a mechanical rather than a photophysical response, a possibility that has been formulated by others who have used anions to actuate molecular switches.14 As part of our contribution to this area of chemistry, we now describe the unique case of a dinuclear AuSb platform, which can be regarded as a molecular analogue of a mechanical three-way switch. The switching element is a phenyl group B


Inorganic Chemistry

Award Paper

Scheme 2. Synthesis of 3 from 2a

a

The reversed reaction showing conversion of 3 into 2 via 4 is also shown.

Figure 5. Crystal structure of 2. Displacement ellipsoids are scaled to the 50% probability level. Interstitial solvent molecules and hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 2: Au−Sb 2.8651(4), Au−Cl1 2.5946(8), Sb−Cl2 2.4757(8), Sb−Cl3 2.4846(8), Sb−C13 2.176(3); P1−Au−P2 166.03(3), Cl1−Au−Sb 160.217(18), Au−Sb−C13 169.52(8), Cl2− Sb−Cl3 170.84(3), C1−Sb−C7 171.78(11).

Table 1. Variation Observed in the Au−Sb Distance in Complexes 2−7 complex

Sb−Au distance (Å)

2 3 4 5 6 7

2.8651(4) 2.7450(14) 2.7327(9) 3.0708(13) 3.3918(5) 2.6886(5)

Figure 6. 31P and 19F NMR resonances of 3 in CDCl3.

signals a relatively weak Au → Sb interaction. Unlike the situation found in the two aforementioned complexes where an electron-withdrawing chloride atom is positioned trans to gold, the electron-donating phenyl ring is situated at the apical position in 2, which causes a decrease in the Lewis acidity of the antimony center along the transannular vector, leading to a weakening of the Sb−Au interaction. It remains that the complex can still be classified as a gold complex supported by an ambiphilic L/Z ligand, with the triaryldichlorostiborane unit acting as the Z-type ligand.17 In fact, we have previously shown that 1 can be oxidized with o-chloranil to afford [(o(Ph2P)C6H4)2(o-C6Cl4O2)ClSb]AuCl, a complex that also possesses a Au → Sb interaction and whose formation is accompanied by an umpolung of the Au−Sb bond.15b,c Stage 2. With this compound in hand, we decided to determine how its structure would respond to the substitution of the antimony-bound chloride ligands by fluoride anions. To this end, compound 2 was allowed to react with 4 equiv of KF in methanol (MeOH), resulting in the formation of complex [(o-(iPr2P)C6H4)2F2SbPh]AuCl (3) as a white, air-stable derivative (Scheme 2). The 31P NMR signal at 93.1 ppm appears as a doublet because of coupling to one of the fluorine nuclei (JP−F = 15.0 Hz; Figure 6). The 19F NMR spectrum of 3 in CDCl3 displays two signals of equal intensity at −20.7 and −147.3 ppm. The first signal is a simple doublet arising from the nonequivalence of the two fluorine nuclei (JF−F = 31.5 Hz). The second signal is a doublet of triplets (JF−F = 31.5 Hz and JP−F = 15.0 Hz). The upfield chemical shifts and JP−F coupling of the signals suggest unsymmetrical coordination of the two fluorine atoms to the antimony atom. The peak at −20.7 ppm

is assigned to the equatorial fluorine atom (Feq), which only coupled with the apical fluorine atom (Fax) with a coupling constant of JF−F = 31.5 Hz. The other upfield peak at −147.3 ppm corresponding to Fax is coupled not only with Feq but also with two phosphorus atoms, resulting in a doublet of triplets. The chemical shifts of these 19F NMR resonances can be compared to those of [(o-(Ph2P)C6H4)2F3Sb]AuCl, which shows a high field resonance for the axial fluorine atom (−133.3 ppm) and a downfield resonance for the equatorial fluorine (−72.0 ppm).15a An elucidation of the structure of the complex confirmed the fact that the antimony-bound phenyl group switched to a coordination site perpendicular to the SbAu core, making the two fluorine atoms inequivalent. Indeed, the structure of 3 shows two fluorine atoms coordinated to the antimony center in a cis fashion with Sb−F bond distances of 1.968(3) Å for Sb−F1 and 1.994(3) Å for Sb−F2 (Figure 7). These Sb−F distances are similar to those observed in Ph4SbF [2.0530(8) Å]18 or AntPh3SbF [2.0530(8) Å; Ant = 9-anthryl].11c Fluoride coordination results in a nearly octahedral geometry about the antimony with the two fluoride ligands located in a cis position.4b Also of interest is the Au−Sb distance of 3 [2.7449(14) Å], which is significantly shorter than that measured for 2 (Table 1). The value of the Sb−Au−Cl1 angle [164.17(3)°] in 3 is more linear than that in 2 [160.217(18)°]. Altogether, these structural peculiarities suggest a strengthening of the Au → Sb interaction upon conversion of 2 into 3. This phenomenon, which we assign to the weaker trans influence of fluoride versus phenyl, signals an C


Inorganic Chemistry

Award Paper

Figure 8. Crystal structure of 4. Displacement ellipsoids are scaled to the 50% probability level. Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 4: Au−Sb 2.7327(9), Au−Cl1 2.5021(5), Sb−F1 1.966(3), Sb−Cl1 2.467(2), Sb−C13 2.178(5); P1−Au−P2 165.37(5), Cl1−Au−Sb 164.65(3), Au−Sb−F1 178.58(10), Cl1−Sb−C13 177.68(15), C1−Sb−C7 166.38(19).

Figure 7. Crystal structure of 3. Displacement ellipsoids are scaled to the 50% probability level. Interstitial solvent molecules and hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 3: Au−Sb 2.7450(14), Au−Cl1 2.5190(18), Sb−F1 1.968(3), Sb−F2 1.994(3), Sb−C13 2.178(5); P1−Au−P2 163.82(5), Cl1−Au−Sb 164.18(3), Au−Sb−F1 178.70(9), F2−Sb− C13 177.53(15), C1−Sb−C7 165.93(17).

the computed Sb−Au distance in 2 (2.88 Å) being longer than that in 3 (2.79 Å). We have analyzed the topology of the electron density using the atoms in molecules (AIM) method, as implemented in AIMAll. For both complexes, this analysis identifies a bond path connecting the two heavy atoms, thereby confirming the presence of a bonding interaction. The value of the Laplacian of the electron density [∇2ρ(r)] at the Sb−Au bond critical point (BCP) of both 2 and 3 is positive, in agreement with the donor−acceptor nature of the Au → Sb bonding.20 It is interesting to note that the value of the electron density at the Sb−Au BCP is lower in 2 [ρ(BCP) = 4.99 × 10−2 e bohr−3] than in 3 [ρ(BCP) = 5.63 × 10−2 e bohr−3; Table 2].

increase in the Lewis acidity of the antimony center in 3. We note, in passing, that the greater trans influence of the aryl substituents, compared to halide ligands, has recently been confirmed for antimony(III) species.19 Conversion of 2 to 3, and, hence, the 90° switch of the phenyl group, is reversible. Indeed, when 3 is treated with 2 equiv of tert-butyldimethylsilyl chloride (TBDMSCl) in CH2Cl2, fluoride abstraction occurs, leading to the formation of TBDMSF and regeneration of the antimony dichloride complex 2. Monitoring this reaction by 31P NMR spectroscopy points to the intermediacy of a new species {[(o-(iPr2P)C6H4)2ClFSbPh]AuCl (4)} characterized by a 19F NMR resonance at −136 ppm, which, by analogy with the chemical shift of Fax in 3, suggested the presence of a fluoride anion trans to the gold center. The 31P NMR spectrum displayed a peak at 95 ppm, the value of which is between the corresponding signals for 2 and 3. This observation led us to speculate that 4 was a mixed halide complex in which one fluoride and one chloride are bound to antimony. Isolating an analytically pure sample of 4 proved to be impossible because its formation could never be completely decoupled from that of 3, even when 1 equiv of TBDMSCl was used. However, through systematic screening of single crystals grown from a CH2Cl2 solution containing an equimolar amount of 3 and TBDMSCl, we succeeded in the structural characterization of 4, which confirmed that it is the mixed halide derivative. This structural assay confirmed that the phenyl group is in the equatorial plane, indicating that the presence of a single fluoride ligand is enough to induce a 90° switch. The structure of 4 is very similar to that of 3, with the fluoride and phenyl ligands positioned trans and cis from the gold atom, respectively. The Sb1−F1 bond distance of 1.966(3) Å is comparable to that found in 3 [1.968(3) Å], whereas the Sb1−Cl1 bond distance [2.467(2) Å] is similar to the Sb−Cl bond in 2 [2.4757(8) Å]. The Sb1− Au1 distance of 2.7327(9) Å in 4 is also very close to that in 3 [2.7450(14)], indicating a stronger Au → Sb interaction (Figure 8 and Table 1). We have computed the structures of 2 and 3 using density functional theory (DFT) methods (Gaussian09: BP86 with 631g for hydrogen and carbon atoms; 6-31+G(d′) for fluorine atoms; 6-31G(d′) for phosphorus and chlorine atoms; ccpVTZ-PP with the Stuttgart relativistic small core for gold and antimony atoms). Optimization of the geometry of these two complexes reproduced the trend observed experimentally, with

Table 2. Selected Parameters for the Sb−Au BCPs compound

ρ(r) (e bohr−3) −2

2

4.99 × 10

3 4 5 7

5.63 5.67 3.13 6.08

× × × ×

10−2 10−2 10−2 10−2

∇2ρ(r) (e bohr−5) −2

2.69 × 10 2.94 3.02 3.71 1.40

× × × ×

10−2 10−2 10−2 10−2

δ(A,B) 0.46 0.50 0.52 0.27 0.54

This difference, which correlates with the shorter Au−Sb bond measured experimentally for 3, indicates that the latter has a stronger Au → Sb interaction than 2, a phenomenon that we rationalize by the presence of an apical fluoride atom trans to the gold atom. It can also be argued that the phenyl group in 2 exerts a strong trans influence, thereby weakening the Au → Sb interaction. A similar conclusion is derived from the delocalization index, which is higher for 3 [δ(A,B) = 0.50] than for 2 [δ(A,B) = 0.46].21 A complementary picture emerges from visualization of the localized orbital locator (LOL) function, a function that maps the electron kinetic energy within a molecule.22 For both complexes, the LOL function, as implemented in Multiwf n, displays a basin with LOL values close to 0.5 between the gold and antimony atoms (Figure 9). As previously explained for other late-transition-metal complexes,23 such a situation corresponds to a slow electron region and is indicative of a bonding interaction between these two atoms. Stage 3. As a next step in our investigation of this system, we became intrigued by the possibility of inducing the translocation of the switching element, namely, the phenyl group, to a third position. With this in mind, we considered strategies that would allow us to induce migration of the phenyl D


Inorganic Chemistry

Award Paper

Figure 9. Top: QTAIM bond path and BCP analysis for 2, 3, 5, and 7. Hydrogen atoms and BCPs featuring ρ(r) values of less than 0.02 e bohr−3 and their corresponding bond paths are omitted for clarity. Bottom: LOL map of complexes 2, 3, 5, and 7 in the plane of Sb−Au−P.

group to the gold atom. It occurred to us that such a process would be facilitated by the creation of a vacant coordination site on the gold atom. To this end, complex 3 was treated with 1 equiv of TlPF6 in dichloromethane at room temperature (Scheme 3). After standard workup, complex 5 was isolated in Scheme 3. Synthesis of 5

Figure 10. Crystal structure of 5. Displacement ellipsoids are scaled to the 50% probability level. Counteranion PF6− and hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 5: Au−Sb 3.0708(13), Sb−F1 1.953(7), Sb−F2 1.955(6), Sb−C13 2.110(10), Au−P1 2.293(3), Au−P2 2.291(3); P1−Au−P2 178.70(11), Au−Sb−C13 177.9(3), F2−Sb−F1 171.4(3), C1−Sb− C7 162.3(4).

80% yield as a white powder. The 31P NMR spectrum of 5 in CDCl3 consists of a resonance at 78.8 ppm, shifted to higher field by about 15 ppm from 3 (93.1 ppm) and a PF6− resonance (−144.2 ppm, JP−F = 712.7 Hz) with a half-intensity ratio. In addition to a PF6− resonance at −73.3 ppm, the 19F NMR spectrum of 5 shows a singlet at −96.9 ppm corresponding to the two fluorine atoms bound to the antimony center. The formation of 5 is reversible. Indeed, the addition of TBACl to a solution of this salt in CDCl3 leads to the clean formation of 3, as confirmed by 31P and 19F NMR spectroscopy. Single crystals of 5 were obtained by the slow vapor diffusion of Et2O into a solution of the compound in CH3CN. The crystallographic measurement of 5 was performed at 253(2) K due to the loss of crystallinity at lower temperatures (Figure 10). The absence of short contacts between the gold atom and the PF6− counterion unambiguously establishes the ionic character of 5. The Sb−Au bond is elongated from 2.7450(14) Å in 3 to 3.0708(13) Å in 5 (Table 1), suggesting a weakening of the Au → Sb donor−acceptor interaction caused by the decreased metallobasicity of the gold center in 5. A further examination of the structure indicates that the F1 and F2 atoms are trans from each other, which is consistent with the detection of a single 19F NMR signal for 5. The Sb−F1 and

Sb−F2 bond lengths of 1.953(7) and 1.955(6) Å, respectively, are close to those observed in difluorostiboranes such as Ph3SbF2 (1.974 Å av.),24 (p-(NMe2)C6H4)3SbF2 (2.272 Å av.),25 and Me3SbF2 (1.997 Å av.).26 The gold atom adopts a Tshaped geometry, as confirmed by the average P−Au−Sb and P1−Au−P2 angles of 89.96° and 178.70(11)°, respectively. The weakening of the Au → Sb donor−acceptor interaction is also reflected by the computational results. Indeed, AIM analysis reveals that both the electron density ρ(r) at the Sb− Au BCP (3.13 × 10−2 e bohr−3) and the delocalization index δ(A,B) in 5 (0.27) are significantly lower than those in 3 [ρ(r) = 5.63 × 10−2 e bohr−3 and δ(A,B) = 0.50; Table 2]. The LOL map of 5 is also very diagnostic, with a clear shrinking of the slow electron region between gold and antimony (Figure 9). The weakening of the Au → Sb interaction results from removal of the chloride trans to antimony, a phenomenon that E


Inorganic Chemistry

Award Paper

we have recently observed upon conversion of [(o-(Ph2P)C6H4)2F3Sb]AuCl into [[(o-(Ph2P)C6H4)2F3Sb]Au]+.15a Similar effects have also been observed by Bourrisou, who found that the Au → B interaction of [[o-(iPr2P)C6H4]3B]AuCl is stronger and shorter than that of [[[o-(iPr2P)C6H4]3B]Au]+.27 A last aspect that deserves comments pertains to the different positions adopted by the phenyl group in 3 and 5. The gold atom in 5 is cationic and inherently more electron-poor than that in 3. We propose that these electronic changes are responsible for the structural reorganization observed upon the conversion of 3 into 5. In 5, the location of the phenyl group trans to gold produces a structure where antimony draws less electron density from the now cationic gold center. With the view of triggering migration of the phenyl group to the gold center, we decided to treat 5 with a fluoride anion source, which we envisioned could bind to antimony and force phenyl group migration to gold. To our surprise, the treatment of 5 with [nBu4N][Ph3SiF2] (TBAT) in CH2Cl2 under inert conditions, led to the formation of a zwitterionic intermediate {[o-(iPr2P)C6H4)2F3SbPh]Au (6)}, which could not be isolated in a bulk amount because of its instability (Scheme 4). The 31P

Figure 11. 19F NMR resonances of 6 in CH2Cl2.

Scheme 4. Reaction of 5 with TBAT To Afford 7: Migration of the Phenyl Group from the Antimony Atom to the Gold Atom via the Intermediacy of 6

NMR spectrum of 6 shows a pseudotriplet at 69.5 ppm with JP−F = 14 Hz, while the 19F NMR spectrum shows three signals at −2.72 ppm (ddt, JF−F(cis) = 60 Hz, JF−F(cis) = 32 Hz, JP−F = 14 Hz), −71.43 ppm (ddt, JF−F(trans) = 80 Hz, JF−F(cis) = 32 Hz, JP−F = 14 Hz), and −128.65 ppm (dd, JF−F(trans) = 80 Hz, JF−F (cis)= 60 Hz), in a 1:1:1 intensity ratio (Figure 11). Upon standing in solution, this intermediate slowly rearranges to give a new complex identified as the target gold(I) aryl complex [(o(iPr2P)C6H4)2F3Sb]AuPh (7; vide supra). Unambiguous characterization of 6 came from a structural elucidation of single crystals obtained by layering the reaction mixture with pentane shortly after the reagents were mixed. Compound 6 crystallizes in the triclinic space group P1̅ with two independent molecules referred to as molecules a and b, respectively. Examination of the structure of 6 reveals its zwitterionic nature. The antimony atom is at the center of an octahedral triaryltrifluoroantimonate anion that sits in proximity to the bis(phosphine)gold(I) cation (Figure 12). The formation of this zwitterion is reminiscent of the behavior of other group 13 containing ligands,28 such as [o-(iPr2P)C6H4]2AlCl, that form related zwitterionic structures when coordinated to gold(I) chloride.28b The most interesting features in the structure of 6 are the short Au−F1 [2.664(3) and 2.655(3) Å for molecule a and b, respectively] and Au−F2 distances [2.675(3) and 2.749(3) Å for molecules a and b,

Figure 12. (a) Solid-state structure of one of the independent molecules of 6. Displacement ellipsoids are scaled to the 50% probability level. Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 6: Au−Sb 3.3918(5), Sb1−F1 2.010(3), Sb−F2 2.009(3), Sb−F3 1.973(3), Sb1−C13 2.158(5), Au− F1 2.664(3), Au−F2 2.675(3); P1−Au−P2 168.20(5). The metrical parameters of the second independent molecule are very similar. (b) QTAIM bond path and BCP analysis for 6 projected in the Au1−F1− F2 plane. The topology of the electron density is also shown. (c) LOL map for 6.

respectively], which show that two of the fluorine atoms are in forced proximity to the gold(I) center. These distances, which are comparable to those observed in [[[o-(Ph2P)C6H4]2F3Sb]Au][SbF6] [2.728(4) Å],15a are noticeably longer than the Au− F bonds of known molecular gold fluoride complexes [2.0281(17) Å for (SIDipp)AuF29 and 2.060(1) Å for [{(SIDipp)Au}2(μ-F)][BF4] with SIDipp = 1,3-bis(2,6-diisopropylphenyl)-4,5-dihydroimidazol-2-ylidene]30 and only correspond to weak and geometrically constrained Au−F interactions. Finally, the Sb−Au distances of 3.3918(5) Å (molecule a) and 3.3888(4) Å (molecule b) rule out any direct F


Inorganic Chemistry

Award Paper

interaction between the gold and antimony centers. This is confirmed by the results of AIM and LOL analyses, which show no bond path and no slow electron basin, respectively, between the two heavy atoms. In turn, one can easily conclude that the addition of a third fluoride anion to the antimony center neutralizes the Lewis acidity of the later and no longer allows for donor−acceptor bonding between the gold and antimony atoms. On the other hand, the presence of Au−F interactions is confirmed by the presence of bond paths connecting the gold atom to the two fluorine atoms with very similar values of the density at the BCP [av. ρ(r) = 2.85 × 10−2 e bohr−3;Figure 12]. Conversion of 6 into 7 occurs over the course of 24−48 h, as indicated by 31P NMR spectroscopy, which shows the appearance of a doublet at 107.3 ppm (JP−F = 18.8 Hz). The 19 F NMR spectrum of 7 exhibits two signals at −83.4 and −121.6 ppm in a 2:1 intensity ratio, suggesting that two of the fluorine atoms are in trans positions. Further examination of the splitting of the 19F NMR signals leads to the following assignments: the peak at −83.4 ppm is assigned to the two Feq atoms with a coupling constant JF−F = 20.6 Hz to the Fax; the signal at −121.6 ppm, which features a pseudoquintet (JF−F = 20.6 Hz and JP−F = 18.8 Hz) atoms, is assigned to Fax (Figure 13). Compound 7 does not revert back to 3 upon treatment with TMSCl.

Figure 14. Crystal structure of one of the independent molecules of 7. Displacement ellipsoids are scaled to the 50% probability level. Hydrogen atoms are omitted for clarity. Selected bond lengths (Å) and angles (deg) for 7: Au−Sb 2.6886(5), Au−C13 2.149(6), Sb−F1 1.997(3), Sb−F2 1.983(3), Sb−F3 1.973(3); P1−Au−P2 171.84(5), C13−Au−Sb 177.14(19), Au−Sb−F3 177.17(10), F1−Sb−F2 176.77(13), C1−Sb−C7 165.2(2).

TMSCl. Finally, the Au−C13 distance [2.149(6) Å] is significantly longer than the average Au−CPh bond distance of 2.054 Å, which could be derived from analysis of the Cambridge Structural Database for complexes featuring a gold phenyl substructure (see the Supporting Information).31 In fact, the Au−CPh bond of 7 appears to be the longest such bond ever measured. We propose that this unusually long bond distance is the result of the unusual square-planar geometry assumed by the gold center.

■

CONCLUSION In summary, we have described how simple fluoride−chloride anion exchange reactions can be used to precisely dial in the position of a phenyl substituent about the dinuclear core of a AuSb complex. While in all three stages the platform retains a Au → Sb interaction whose presence is unambiguously established using both experiment and theory, two of the observed intermediates involved between stages 2 and 3 have a disrupted transannular bond. The first one is the cationic derivative 5 in which the absence of an anionic ligand at gold reduces the metallobasicity of the latter, drastically weakening the Au → Sb interaction. The second one is the zwitterionic derivative 6, which no longer possesses a Au → Sb interaction as a result of fluoride anion addition to the antimony center. Altogether, these results allow us to introduce a unique mechanical three-way switch actuated by anions. We propose that such switches could also be of use in the domain of anion sensing, a direction that we are further exploring.

Figure 13. 31P and 19F NMR resonances of 7 in CDCl3.

Single crystals of 7 were grown by vapor diffusion of Et2O into a concentrated CH2Cl2 solution (Figure 14). The solidstate structure shows that the three fluorine atoms are attached to the antimony center, which adopts an octahedral geometry. With P1−Au−P2 and C13−Au−Sb angles of 171.84(5)° and 177.14(19)°, respectively, the gold atom is in a distorted square-planar geometry with the phenyl group positioned trans from the gold atom. The Sb−Au bond length [2.6886(5) Å] is shorter than that in complexes 2 [2.8651(4) Å], 3 [2.7450(14) Å], and 5 [3.0708(13) Å], indicating a strengthening of the Au−Sb core (Table 1). This effect can be assigned to the increased acidity of the trifluorodiarylstiborane unit and the increased metallobasicity of the gold center, which is now substituted by a strong trans-influencing phenyl substituent. These effects are also reflected in the AIM results, which show the highest electron density ρ(r) at the Sb−Au BCP (6.08 × 10−2 e bohr−3) and the highest delocalization index [δ(A,B) = 0.54] of the series of complexes described in this paper (Table 2). The LOL map of 7 is also unambiguous, with a very developed slow electron region between the gold and antimony atoms (Figure 9). The stability of this structure is also reflected by its reluctance to revert back to 3 upon treatment with

■

EXPERIMENTAL SECTION

General Considerations. (tht)AuCl (tht = tetrahydrothiophene),32 o-(iPr2P)C6H4Br,33 PhICl2,34 and PhSbCl235 were prepared according to the reported procedures. Solvents were dried by passing through an alumina column (n-pentane and CH2Cl2) or by reflux under N2 over Na/K (Et2O and THF). All other solvents were used as received. All commercially available chemicals were purchased and used as provided (SbCl3, nBu4NF·3H2O, and TBAT from Aldrich, TlPF6 from Strem, TBDMSCl from Chem Impex Int’l Inc., and TBACl from Acros). All air- and moisture-sensitive manipulations were carried out under an atmosphere of dry N2, employing either a glovebox or standard Schlenk techniques. Ambient-temperature NMR spectra were recorded on a Varian Unity Inova 500 FT NMR G


Inorganic Chemistry

Award Paper

spectrometer (499.42 MHz for 1H, 125.58 MHz for 13C, 202.17 MHz for 31P, and 469.93 MHz for 19F). Chemical shifts (δ) are given in ppm and are referenced against residual solvent signals (1H and 13C) or external H3PO4 (31P) and BF3·Et2O (19F). Elemental analyses were performed at Atlantic Microlab (Norcross, GA). Synthesis of 2. A solution of PhICl2 (17 mg, 0.06 mmol) in CH2Cl2 (1 mL) was added dropwise to a solution of 1 (50 mg, 0.06 mmol) in CH2Cl2 (5 mL) at ambient temperature. The reaction was stirred for 10 min before removal of the solvent in vacuo. The resulting yellow solid was washed with pentane (2 × 3 mL) and dried in vacuo to afford 49 mg (91%) of 2 as a yellow, nonphotoluminescent powder. Single crystals of 2 suitable for X-ray diffraction were obtained by vapor diffusion of pentane into a solution of the compound in CHCl3. 1 H NMR (499.43 MHz, CDCl3): δ 8.51 (dd, 2H, 3JH−H = 7.00 Hz, 3 JH−P = 2.33 Hz, o-P(Sb)C6H4), 7.79 (m, 2H, o-P(Sb)C6H4), 7.56 (m, 3H, SbPhCH), 7.41 (pseudo-t, 2H, 3JH−H = 7.00 Hz, o-P(Sb)C6H4), 7.32 (d, 2H, 3JH−H = 8.38 Hz, o-SbPhCH), 7.23 (pseudo-t, 2H, 3JH−H = 7.00 Hz, o-P(Sb)C6H4), 3.46 (m, 4H, CHCH3), 1.41 (dd, 12H, 3JH−H = 7.00 Hz, 3JH−P = 18.26 Hz, CHCH3), 1.30 (dd, 12H, 3JH−H = 7.00 Hz, 3JH−P = 18.26 Hz, CHCH3). 31P{1H} NMR (202.17 MHz; CDCl3): δ 103.68. 13C{1H} NMR (125.58 MHz, CDCl3): δ 178.59 (pseudo-t, JC−P = 29.05 Hz), 142.09 (s), 136.21 (s), 133.02 (s), 131.72 (pseudo-t, JC−P = 9.32 Hz), 131.22 (pseudo-t, JC−P = 5.45 Hz), 129.58 (s), 129.03 (s), 116.27 (pseudo-t, JC−P = 27.15 Hz), 27.75 (pseudo-t, JC−P = 14.40 Hz), 19.55 (s, CH3iPr), 19.03 (s, CH3iPr). Elem anal. Calcd for C30H41AuCl3P2Sb·0.65CHCl3: C, 38.10; H, 4.34. Found: C, 38.09; H, 4.45. This compound crystallizes with one interstitial molecule of CHCl3. This elemental analysis result suggests partial loss of the interstitial solvent during shipment and handling. Synthesis of 3. A solution of KF (10 mg, 0.20 mmol) in MeOH (1 mL) was added to a solution of 2 (40 mg, 0.05 mmol) in THF (3 mL) and stirred at ambient temperature for 30 min, resulting in the precipitation of a white solid. The solvent was removed in vacuo, and the residue extracted with CH2Cl2 (5 mL). The resulting mixture was filtered over Celite and concentrated to ca. 1 mL. The addition of pentane (5 mL) resulted in the precipitation of a white, nonphotoluminescent powder that was filtered, washed with MeOH (3 × 3 mL), and dried in vacuo to afford 33 mg (85%) of 3. Single crystals of 3 suitable for X-ray diffraction were obtained by slow evaporation of the compound in CH2Cl2/Et2O (1:1). 1H NMR (499.43 MHz, CDCl3): δ 8.74 (d, 2H, 3JH−H = 7.84 Hz, o-P(Sb)C6H4), 7.76 (m, 2H, m-P(Sb)C6H4), 7.69 (pseudo-t, 2H, 3JH−H = 7.84 Hz, P(Sb)C6H4), 7.54 (pseudo-t, 2H, 3JH−H = 6.39 Hz, P(Sb)C6H4), 7.03 (pseudo-t, 1H, 3 JH−H = 6.39 Hz, p-SbPhCH), 6.95 (pseudo-t, 2H, 3JH−H = 6.39 Hz, mSbPhCH), 6.76 (d, 2H, 3JH−H = 6.39 Hz, o-SbPhCH), 3.40 (br, 2H, CHCH3), 3.26 (br, 2H, CHCH3), 1.34 (dd, 12H, 3JH−H = 7.35 Hz, 3 JH−P = 20.05 Hz, CHCH3), 1.21 (dd, 12H, 3JH−H = 7.35 Hz, 3JH−P = 20.05 Hz, CHCH3). 31P{1H} NMR (202.17 MHz, CDCl3): δ 93.13 (d, 3 JP−F = 14.96 Hz). 19F NMR (469.93 MHz, CDCl3): δ −20.67 (d, 1F, 2 JF−F 31.49 Hz), −147.32 (dt, 1F, 2JF−F = 31.49 Hz, 3JF−P = 14.96 Hz). 13 C{1H} NMR (125.58 MHz, CDCl3): δ 161.06 (s), 154.33 (s), 139.60 (s), 135.57 (pseudo-t, JC−P = 9.22 Hz), 133.21 (s), 133.00 (s), 131.29 (br), 129.01 (br), 128.74 (s), 127.96 (s), 29.00 (pseudo-t, JC−P = 14.45 Hz), 26.88 (pseudo-t, JC−P = 14.45 Hz), 19.38 (s, CH3iPr), 19.17 (s, CH3iPr), 18.82 (s, CH3iPr), 18.53 (s, CH3iPr). Elem anal. Calcd for C30H41AuClF2P2Sb: C, 42.11; H, 4.83. Found: C, 42.08; H, 4.95. Characterization of 4. A solution of TBDMSCl (1.9 mg, 0.012 mmol) in dry CH2Cl2 (0.2 mL) was added to a solution of 3 (10.8 mg, 0.012 mmol) in dry CH2Cl2 (0.4 mL). The reaction mixture was transferred to an NMR tube. and the formation of 4 was monitored by the heteronuclear NMR. The color changed from colorless to yellow within 2 h, indicating the conversion of 3 to 2 via the formation of 4. After 24 h, the reaction reached equilibrium, with 2, 4, and 3 present in the solution in a 1.9:8.2:1 ratio. Single crystals of 4 suitable for X-ray diffraction were obtained by layering the reaction mixture with pentane. 31P{1H} NMR (202.17 MHz, CDCl3): δ 95.89 (bs, 2P, PiPr2). 19F NMR (469.93 MHz, CDCl3): δ −136.42 (bs, 1F). Synthesis of 5. A solution of TlPF6 (16 mg, 0.046 mmol) in CH2Cl2 (1 mL) was added to a solution of 3 (40 mg, 0.046 mmol) in

CH2Cl2 (3 mL) and stirred at ambient temperature for 30 min, resulting in the precipitation of a white TlCl salt. The resulting mixture was filtered over Celite and concentrated to ca. 1 mL. The addition of pentane (5 mL) resulted in the precipitation of a white, nonphotoluminescent powder, which was filtered, washed with pentane (3 × 3 mL), and dried in vacuo to afford 36 mg (80%) of 5. Single crystals of 5 suitable for X-ray diffraction were obtained by vapor diffusion of Et2O into a solution of the compound in CH3CN. 1H NMR (499.43 MHz, CDCl3): δ 7.89 (d, 2H, 3JH−H = 7.62 Hz, oP(Sb)C6H4), 7.77 (m, 2H, P(Sb)C6H4), 7.66 (pseudo-t, 2H, 3JH−H = 7.62 Hz, SbPhCH), 7.61 (m, 3H, P(Sb)C6H4), 7.53 (d, 2H, 3JH−H = 7.62 Hz, o-P(Sb)C6H4), 7.44 (pseudo-t, 2H, 3JH−H = 7.62 Hz, SbPhCH), 3.29 (m, 4H, CHCH3), 1.47 (dd, 12H, 3JH−H = 7.59 Hz, 3 JH−P = 19.58 Hz, CHCH3), 1.32 (dd, 12H, 3JH−H = 7.59 Hz, 3JH−P = 19.58 Hz, CHCH3). 31P{1H} NMR (202.17 MHz, CDCl3): δ 78.79 (s, 2P, PiPr2), −144.23 (sept, 1P, 1JP−F = 712.73 Hz, PF6−). 19F NMR (469.93 MHz, CDCl3): δ −73.30 (d, 6F, 2JF−P 712.73 Hz, PF6−), −96.86 (s, 2F, SbF2). 13C{1H} NMR (125.58 MHz, CDCl3): δ 158.68 (br), 136.09 (s), 135.51 (pseudo-t, JC−P = 6.94 Hz), 135.07 (s), 134.04 (s), 132.82 (s), 132.27 (s), 131.59 (pseudo-t, JC−P = 3.50 Hz), 130.93 (pseudo-t, JC−P = 29.25 Hz), 130.18 (s), 26.88 (pseudo-t, JC−P = 14.95 Hz), 20.62 (s, CH3iPr), 19.03 (s, CH3iPr). Elem anal. Calcd for C30H41AuF8P3Sb: C, 37.33, H, 4.28. Found: C, 36.99, H, 4.28. Characterization of 6. A solution of TBAT (11.18 mg, 0.02 mmol) in CDCl3 (2 mL) was added dropwise to a solution of 5 (20 mg, 0.02 mmol) also in CDCl3 (1 mL). It was left to stir for 10 min, and an aliquot of 0.5 mL was transferred to an NMR tube. Single crystals of 6 suitable for X-ray diffraction were obtained by layering a 1:1 mixture of 5 and TBAT in CH2Cl2 with pentane. 31P{1H} NMR (202.17 MHz, CDCl3): δ 69.5 (t, 3JP−F = 14 Hz). 19F NMR (469.93 MHz; CDCl3): δ −2.72 (ddt, 1F, 3JP−F = 14 Hz, 2JF−F(cis) = 32 Hz, 2 JF−F(cis) = 60 Hz), −71.43 (ddt, 1F, 2JF−F(trans) = 80 Hz, 2JF−F(cis) = 32 Hz, 3JF−P = 14 Hz), −128.65 (dd, 1F, 2JF−F(trans) = 80 Hz, 3JF−P = 60 Hz). Synthesis of 7. A solution of tetra-n-butylammonium fluoride (8 mg, 0.03 mmol) in CH2Cl2 (2 mL) was added to a solution of 5 (25 mg, 0.026 mmol) in CH2Cl2 (3 mL) and stirred at ambient temperature for 12 h, resulting in the precipitation of a white solid. The solvent was removed in vacuo and the residue extracted with CH2Cl2 (5 mL). The resulting mixture was filtered over Celite and concentrated to ca. 1 mL. The addition of pentane (5 mL) resulted in the precipitation of a white, nonphotoluminescent powder, which was filtered, washed with MeOH (3 × 3 mL), and dried in vacuo to afford 15 mg (67%) of 7. Single crystals of 7 suitable for X-ray diffraction were obtained by slow evaporation of the compound in CH2Cl2/Et2O (1:1). 1H NMR (499.43 MHz, CDCl3): δ 9.11 (d, 2H, 3JH−H = 8.37 Hz, o-P(Sb)C6H4), 7.88 (d, 2H, o-P(Sb)C6H4, 3JH−H = 8.85 Hz), 7.69 (pseudo-t, 2H, 3JH−H = 7.28 Hz, m-P(Sb)C6H4), 7.49 (pseudo-t, 2H, 3 JH−H = 7.28 Hz, m-P(Sb)C6H4), 7.41 (d, 2H, 3JH−H = 8.32 Hz, oSbPhCH), 7.33 (pseudo-t, 2H, 3JH−H = 8.32 Hz, m-SbPhCH), 7.10 (pseudo-t, 1H, 3JH−H = 8.32 Hz, p-SbPhCH), 3.45 (m, 4H, CHCH3), 1.17 (dd, 12H, 3JH−H = 8.22 Hz, 3JH−P = 18.62 Hz, CHCH3), 0.87 (dd, 12H, 3JH−H = 8.22 Hz, 3JH−P = 18.62 Hz, CHCH3). 31P{1H} NMR (202.17 MHz, CDCl3): δ 107.31 (d, 3JP−F = 18.82 Hz). 19F NMR (469.93 MHz, CDCl3): δ −83.89 (d, 2F, 2JF−F 20.61 Hz), −121.62 (dt, 1F, 2JF−F = 20.61 Hz, 3JF−P = 18.82 Hz). 13C{1H} NMR (125.58 MHz, CDCl3): δ 139.31 (s), 136.89 (s), 136.81 (s), 133.19 (s), 133.00 (s), 130.11 (s), 129.28 (s), 129.19 (s), 125.87 (s), 123.96 (s), 27.09 (pseudo-t, JC−P = 16.63 Hz), 18.43 (s, CH3iPr), 18.10 (s, CH3iPr). Elem anal. Calcd for C30H41AuF3P2Sb: C, 42.93; H, 4.92. Found: C, 42.81; H, 4.91. Crystallography. All crystallographic measurements were performed at 110(2) K using a Bruker SMART APEX II diffractometer with a CCD area detector (graphite-monochromated Mo Kα radiation, λ = 0.71073 Å, and ω scans with a 0.5° step in ω) at 110 K. In each case, a specimen of suitable size and quality was selected and mounted on a nylon loop. The semiempirical method SADABS was applied for absorption correction. The structures were solved by direct methods and refined by the full-matrix least-squares techniques against F2 with anisotropic temperature parameters for all nonH


Inorganic Chemistry

Award Paper

hydrogen atoms. All hydrogen atoms were geometrically placed and refined in a riding model approximation. Data reduction and further calculations were performed using the Bruker Apex2 (2013) and SHELXTL program packages. Two interstitial water molecules in the structure of 7 were modeled without their hydrogen atom, which could not be experimentally located. Theoretical Calculations. DFT calculations (full geometry optimization) were carried out upon starting from the crystal structure geometries with the Gaussian09 program (BP8636 with 6-31G for hydrogen and carbon atoms; 6-31+G(d′) for fluorine atoms; 631G(d′) for phosphorus and chlorine atoms; cc-pVTZ-PP with a Stuttgart relativistic small core for gold37 and antimony38 atoms). Frequency calculations performed on the optimized geometries found no imaginary frequency except in the case for 5, for which a weakly imaginary frequency (−8.17 cm−1) associated with the rotation of the PF6 anion was observed. QTAIM calculations were carried out on the wave functions derived from the optimized structures using the AIMAll program.39 The LOL plots were obtained using Multiwf n, version 3.3.8.40

■

Iou-Sheng Ke was born in 1981 in Taipei, Taiwan. He received his B.S. and M.S. degrees from the National Taiwan University. After completing his military service, he joined the Gabbai ̈ group at Texas A&M University in 2008 to study the chemistry antimony Lewis acids. After obtaining his Ph.D. in June 2013, he joined the Dow Chemical Electronic Material business unit as a senior chemist. He is currently working on the development of semiconductor materials such as atomic layer deposition precursors and microlithography photoresists.

ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.inorgchem.6b01290.

■

X-ray crystallographic data of 2−7 in CIF format (CIF) NMR spectra for compounds 2−7, Cartesian coordinates of the optimized structures, QTAIM and LOL analyses of 4, and a histogram for the Au−CPh bonds obtained using Mogul 1.7.1 (PDF)

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. ̂ François P. Gabbai ̈ received a Maitrise from the University of Bordeaux, a Ph.D. from The University of Texas at Austin under Alan Cowley, and a Habilitation from the Technical University of Munich under Hubert Schmidbaur. He started at Texas A&M University in 1998 where he now holds the Arthur E. Martell Chair of Chemistry. His research deals with the chemistry of late-transition-metal and pblock elements. He is on the advisory board of several journals and serves as an Associated Editor for Organometallics. He is a Fellow of the American Chemical Society and a Fellow of the Royal Society of Chemistry and was recently recognized with the 2016 Amercian Chemical Society F. Albert Cotton Award in Synthetic Inorganic Chemistry.

Notes

The authors declare no competing financial interest. Biographies

■

ACKNOWLEDGMENTS This work was supported by the National Science Foundation (Grant CHE-1566474), the Welch Foundation (Grant A1423), and Texas A&M University (Arthur E. Martell Chair of Chemistry).

■

Srobona Sen was born in 1989 in Kolkata, India. After receiving her B.Sc. degree from Presidency College, Kolkata, India, in 2010, she moved to IIT Kanpur, where she obtained a M.Sc. degree in 2012. The same year, she was accepted in the Ph.D. program at Texas A&M University and joined the Gabbai ̈ group. She is currently investigating the chemistry of heterobimetallic complexes featuring main-group centers.

REFERENCES

(1) (a) Bowman-James, K., Bianchi, A., Garcia-Espana, E., Eds.; Anion Coordination Chemistry; Wiley-VCH Verlag GmbH & Co. KGaA: Berlin, 2012. (b) Busschaert, N.; Caltagirone, C.; Van Rossom, W.; Gale, P. A. Chem. Rev. 2015, 115, 8038−8155. (c) Santos-Figueroa, L. E.; Moragues, M. E.; Climent, E.; Agostini, A.; Martinez-Manez, R.; Sancenon, F. Chem. Soc. Rev. 2013, 42, 3489−3613. (d) Madhuprasad;

I


Inorganic Chemistry

Award Paper

Bhat, M. P.; Jung, H.-Y.; Losic, D.; Kurkuri, M. D. Chem. - Eur. J. 2016, 22, 6148−6178. (e) Lee, M. H.; Kim, J. S.; Sessler, J. L. Chem. Soc. Rev. 2015, 44, 4185−4191. (f) Gale, P. A.; Busschaert, N.; Haynes, C. J. E.; Karagiannidis, L. E.; Kirby, I. L. Chem. Soc. Rev. 2014, 43, 205−241. (g) Chang, K.-C.; Sun, S.-S.; Odago, M. O.; Lees, A. J. Coord. Chem. Rev. 2015, 284, 111−123. (2) (a) Zhou, Y.; Zhang, J. F.; Yoon, J. Chem. Rev. 2014, 114, 5511− 5571. (b) Guo, Z.; Shin, I.; Yoon, J. Chem. Commun. 2012, 48, 5956− 5967. (c) Hudson, Z. M.; Wang, S. Dalton Trans. 2011, 40, 7805− 7816. (d) Galbraith, E.; James, T. D. Chem. Soc. Rev. 2010, 39, 3831− 3842. (e) Xu, Z.; Chen, X.; Kim, H. N.; Yoon, J. Chem. Soc. Rev. 2010, 39, 127−137. (f) Jäkle, F. Chem. Rev. 2010, 110, 3985−4022. (3) (a) Zhao, H.; Leamer, L. A.; Gabbaï, F. P. Dalton Trans. 2013, 42, 8164−8178. (b) Wade, C. R.; Broomsgrove, A. E. J.; Aldridge, S.; Gabbaï, F. P. Chem. Rev. 2010, 110, 3958−3984. (c) Hudnall, T. W.; Chiu, C.-W.; Gabbaï, F. P. Acc. Chem. Res. 2009, 42, 388−397. (4) (a) Hirai, M.; Cho, J.; Gabbaï, F. P. Chem. - Eur. J. 2016, 22, 6537−6541. (b) Jones, J. S.; Wade, C. R.; Gabbaï, F. P. Organometallics 2015, 34, 2647−2654. (c) Pan, B.; Gabbaï, F. P. J. Am. Chem. Soc. 2014, 136, 9564−9567. (5) (a) Olah, G. A. J. Org. Chem. 2005, 70, 2413−2429. (b) Olah, G. A.; Klopman, G.; Schlosberg, R. H. J. Am. Chem. Soc. 1969, 91, 3261− 3268. (c) Olah, G. A.; Schlosberg, R. H. J. Am. Chem. Soc. 1968, 90, 2726−2727. (d) Gutmann, V.; Hubacek, H.; Steininger, A. Monatsh. Chem. 1964, 95, 678−686. (6) Krossing, I.; Raabe, I. Chem. - Eur. J. 2004, 10, 5017−5030. (7) Ghorab, M. F.; Winfield, J. M. J. Fluorine Chem. 1990, 49, 367− 383. (8) (a) Sivaev, I. B.; Bregadze, V. I. Coord. Chem. Rev. 2014, 270− 271, 75−88. (b) Erker, G. Dalton Trans. 2005, 1883−1890. (c) Piers, W. E. Adv. Organomet. Chem. 2004, 52, 1−76. (d) Chen, E. Y.-X.; Marks, T. J. Chem. Rev. 2000, 100, 1391−1434. (9) (a) Robertson, A. P. M.; Chitnis, S. S.; Jenkins, H. A.; McDonald, R.; Ferguson, M. J.; Burford, N. Chem. - Eur. J. 2015, 21, 7902−7913. (b) Sharutin, V. V.; Sharutina, O. K.; Pakusina, A. P.; Platonova, T. P.; Zadachina, O. P.; Gerasimenko, A. V. Russ. J. Coord. Chem. 2003, 29, 89−92. (c) Fukin, G. K.; Zakharov, L. N.; Domrachev, G. A.; Fedorov, A. Y.; Zaburdyaeva, S. N.; Dodonov, V. A. Russ. Chem. Bull. 1999, 48, 1722−1732. (d) Dodonov, V. A.; Fedorov, A. Y.; Fukin, G. K.; Zaburdyaeva, S. N.; Zakharov, L. N.; Ignatenko, A. V. Main Group Chem. 1999, 3, 15−22. (e) Holmes, R. R.; Day, R. O.; Chandrasekhar, V.; Holmes, J. M. Inorg. Chem. 1987, 26, 157−163. (f) Breunig, H. J.; Koehne, T.; Moldovan, O.; Preda, A. M.; Silvestru, A.; Silvestru, C.; Varga, R. A.; Piedra-Garza, L. F.; Kortz, U. J. Organomet. Chem. 2010, 695, 1307−1313. (g) Nishii, N.; Matsumura, Y.; Okawara, R. J. Organomet. Chem. 1971, 30, 59−65. (h) Nishii, N.; Hashimoto, K.; Okawara, R. J. Organomet. Chem. 1973, 55, 133−137. (i) Tunde Bamgboye, T.; Begley, M. J.; Bryan Sowerby, D. J. Organomet. Chem. 1989, 362, 77−85. (10) (a) Hirai, M.; Gabbaï, F. P. Angew. Chem., Int. Ed. 2015, 54, 1205−1209. (b) Jean, M. Anal. Chim. Acta 1971, 57, 438−439. (c) Bowen, L. H.; Rood, R. T. J. Inorg. Nucl. Chem. 1966, 28, 1985− 1990. (11) (a) Hirai, M.; Myahkostupov, M.; Castellano, F. N.; Gabbaï, F. P. Organometallics 2016, 35, 1854. (b) Hirai, M.; Gabbaï, F. P. Chem. Sci. 2014, 5, 1886−1893. (c) Ke, I.-S.; Myahkostupov, M.; Castellano, F. N.; Gabbaï, F. P. J. Am. Chem. Soc. 2012, 134, 15309−15311. (12) Wade, C. R.; Ke, I.-S.; Gabbaï, F. P. Angew. Chem., Int. Ed. 2012, 51, 478−481. (13) (a) Benjamin, S. L.; Reid, G. Coord. Chem. Rev. 2015, 297−298, 168−180. (b) Benjamin, S. L.; Levason, W.; Light, M. E.; Reid, G.; Rogers, S. M. Organometallics 2014, 33, 2693−2695. (c) Benjamin, S. L.; Levason, W.; Reid, G.; Warr, R. P. Organometallics 2012, 31, 1025− 1034. (14) Chao, S. T.; Lara, N. C.; Lin, S.; Day, M. W.; Agapie, T. Angew. Chem., Int. Ed. 2011, 50, 7529−7532. (15) (a) Yang, H.; Gabbaï, F. P. J. Am. Chem. Soc. 2015, 137, 13425− 13432. (b) Ke, I.-S.; Gabbaï, F. P. Inorg. Chem. 2013, 52, 7145−7151.

(c) Wade, C. R.; Gabbaï, F. P. Angew. Chem., Int. Ed. 2011, 50, 7369− 7372. (16) Tokunaga, T.; Seki, H.; Yasuike, S.; Ikoma, M.; Kurita, J.; Yamaguchi, K. Tetrahedron 2000, 56, 8833−8839. (17) (a) Bouhadir, G.; Amgoune, A.; Bourissou, D. Adv. Organomet. Chem. 2010, 58, 1−107. (b) Jones, J. S.; Gabbaï, F. P. Acc. Chem. Res. 2016, 49, 857. (c) Jones, J. S.; Gabbaï, F. P. Chem. Lett. 2016, 45, 376−384. (d) Bouhadir, G.; Bourissou, D. Chem. Soc. Rev. 2016, 45, 1065−1079. (e) Cammarota, R. C.; Lu, C. C. J. Am. Chem. Soc. 2015, 137, 12486−12489. (f) Barnett, B. R.; Moore, C. E.; Rheingold, A. L.; Figueroa, J. S. J. Am. Chem. Soc. 2014, 136, 10262−10265. (g) Anderson, J. S.; Rittle, J.; Peters, J. C. Nature 2013, 501, 84−87. (h) Kameo, H.; Nakazawa, H. Chem. - Asian J. 2013, 8, 1720−1734. (i) Braunschweig, H.; Dewhurst, R. D. Dalton Trans. 2011, 40, 549− 558. (j) Rudd, P. A.; Liu, S.; Gagliardi, L.; Young, V. G.; Lu, C. C. J. Am. Chem. Soc. 2011, 133, 20724−20727. (k) Amgoune, A.; Bourissou, D. Chem. Commun. 2011, 47, 859−871. (l) Hill, A. F. Organometallics 2006, 25, 4741−4743. (m) Parkin, G. Organometallics 2006, 25, 4744−4747. (n) Shriver, D. F. Acc. Chem. Res. 1970, 3, 231− 238. (18) Sharutin, V. V.; Sharutina, O. K.; Pakusina, A. P.; Smirnova, S. A.; Pushilin, M. A. Russ. J. Coord. Chem. 2005, 31, 108−114. (19) Chitnis, S. S.; Burford, N.; McDonald, R.; Ferguson, M. J. Inorg. Chem. 2014, 53, 5359−5372. (20) Macchi, P.; Sironi, A. Coord. Chem. Rev. 2003, 238−239, 383− 412. (21) Bader, R. F. W.; Stephens, M. E. J. Am. Chem. Soc. 1975, 97, 7391−7399. (22) (a) Schmider, H. L.; Becke, A. D. J. Chem. Phys. 2002, 116, 3184−3193. (b) Schmider, H. L.; Becke, A. D. J. Mol. Struct.: THEOCHEM 2000, 527, 51−61. (23) (a) Tsipis, A. C.; Gkekas, G. N. Dalton Trans. 2013, 42, 8307− 8316. (b) Forniés, J.; Fortuño, C.; Ibáñez, S.; Martín, A.; Mastrorilli, P.; Gallo, V.; Tsipis, A. Inorg. Chem. 2013, 52, 1942−1953. (24) Chekhlov, A. N. Dokl. Akad. Nauk 1993, 328, 205−208. (25) Sharutin, V.; Sharutin. Russ. J. Gen. Chem. 1999, 69, 1414−1417. (26) Schwarz, W.; Guder, H. J. Z. Anorg. Allg. Chem. 1978, 444, 105− 111. (27) Sircoglou, M.; Bontemps, S.; Bouhadir, G.; Saffon, N.; Miqueu, K.; Gu, W.; Mercy, M.; Chen, C.-H.; Foxman, B. M.; Maron, L.; Ozerov, O. V.; Bourissou, D. J. Am. Chem. Soc. 2008, 130, 16729− 16738. (28) (a) Sircoglou, M.; Mercy, M.; Saffon, N.; Coppel, Y.; Bouhadir, G.; Maron, L.; Bourissou, D. Angew. Chem., Int. Ed. 2009, 48, 3454− 3457. (b) Devillard, M.; Nicolas, E.; Appelt, C.; Backs, J.; MalletLadeira, S.; Bouhadir, G.; Slootweg, J. C.; Uhl, W.; Bourissou, D. Chem. Commun. 2014, 50, 14805−14808. (c) Cowie, B. E.; Emslie, D. J. H.; Jenkins, H. A.; Britten, J. F. Inorg. Chem. 2010, 49, 4060−4072. (d) Cowie, B. E.; Emslie, D. J. H. Organometallics 2015, 34, 2737− 2746. (e) Boudreau, J.; Fontaine, F.-G. Organometallics 2011, 30, 511− 519. (29) Laitar, D. S.; Muller, P.; Gray, T. G.; Sadighi, J. P. Organometallics 2005, 24, 4503−4505. (30) Wyss, C. M.; Tate, B. K.; Bacsa, J.; Wieliczko, M.; Sadighi, J. P. Polyhedron 2014, 84, 87−95. (31) Bruno, I. J.; Cole, J. C.; Kessler, M.; Luo, J.; Motherwell, W. D. S.; Purkis, L. H.; Smith, B. R.; Taylor, R.; Cooper, R. I.; Harris, S. E.; Orpen, A. G. J. Chem. Inf. Comput. Sci. 2004, 44, 2133−2144. (32) Uson, R.; Laguna, A.; Laguna, M.; Briggs, D. A.; Murray, H. H.; Fackler, J. P. Inorganic Synthesis; John Wiley & Sons, Inc.: New York, 2007; pp 85−91. (33) Korshin, E. E.; Leitus, G.; Shimon, L. J. W.; Konstantinovski, L.; Milstein, D. Inorg. Chem. 2008, 47, 7177−7189. (34) Zhao, X.-F.; Zhang, C. Synthesis 2007, 2007, 551−557. (35) Chalmers, B. A.; Bühl, M.; Athukorala Arachchige, K. S.; Slawin, A. M. Z.; Kilian, P. Chem. - Eur. J. 2015, 21, 7520−7531. (36) (a) Becke, A. D. Phys. Rev. A: At., Mol., Opt. Phys. 1988, 38, 3098−3100. (b) Perdew, J. P. Phys. Rev. B: Condens. Matter Mater. Phys. 1986, 33, 8822−8824. J


Inorganic Chemistry

Award Paper

(37) (a) Peterson, K. A.; Puzzarini, C. Theor. Chem. Acc. 2005, 114, 283−296. (b) Figgen, D.; Rauhut, G.; Dolg, M.; Stoll, H. Chem. Phys. 2005, 311, 227−244. (38) (a) Peterson, K. A. J. Chem. Phys. 2003, 119, 11099−11112. (b) Metz, B.; Stoll, H.; Dolg, M. J. Chem. Phys. 2000, 113, 2563−2569. (39) Keith, T. A. AIMAll; TK Gristmill Software: Overland Park, KS, 2014. (40) (a) Lu, T.; Chen, F. J. Mol. Graphics Modell. 2012, 38, 314−323. (b) Lu, T.; Chen, F. J. Comput. Chem. 2012, 33, 580−592.

K


Anion-Controlled Positional Switching of a Phenyl Group about the

Recommend Documents