Coordination Chemistry of Anticrowns. Isolation of the Chloride

Jun 22, 2017 - Coordination Chemistry of Anticrowns. Isolation of the Chloride Complex of the Four-Mercury Anticrown {[(o,o′-C6F4C6F4Hg)4]Cl}− fro...
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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 Kirill I. Tugashov,† Dmitry A. Gribanyov,† Fedor M. Dolgushin,† Alexander F. Smol′yakov,†,‡ Alexander S. Peregudov,† Zinaida S. Klemenkova,† Ol′ga V. Matvienko,† Irina A. Tikhonova,† and Vladimir B. Shur*,† †

A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Street 28, 119991 Moscow, Russia ‡ Faculty of Science, RUDN University, Miklukho-Maklaya Street 6, 117198 Moscow, Russia S Supporting Information *

ABSTRACT: The paper reports that the interaction of o,o′-dilithiooctafluorobiphenyl with HgCl2 in ether results in the formation of the lithium chloride complex Li{[(o,o′-C6F4C6F4Hg)4]Cl} (11) of the four-mercury anticrown (o,o′-C6F4C6F4Hg)4 (12) along with the earlier isolated and characterized three-mercury anticrown (o,o′-C6F4C6F4Hg)3 (2). The complex was identified by the reaction with 12-crown-4 and determination of the structure of the [Li(12-crown-4)2]{[(o,o′C6F4C6F4Hg)4]Cl} (13) formed. According to an X-ray analysis, the chloride anion in 13 is simultaneously coordinated with all four Hg centers of the anticrown, forming with them a pyramidal Hg4Cl fragment. The reaction of 11 (in the form of an acetonitrile solvate, 11·nMeCN) with boiling water leads to removal of LiCl from 11 and to the formation of free anticrown 12, the subsequent recrystallization of which from o-xylene affords the o-xylene complex {[(o,o′-C6F4C6F4Hg)4](o-Me2C6H4)2} (14). The obtained 14 forms in the crystal infinite chains consisting of alternating anticrown units and bridging o-xylene moieties. Another o-xylene molecule in each macrocyclic fragment of the chain plays the role of a terminal ligand. In both cases, the oxylene ligands in 14 are bonded to only one Hg center of the corresponding mercuramacrocycle. The back-conversion of complex 14 into 12 and o-xylene proceeds in the course of its thermal decomposition under vacuum at 100−120 °C. The reaction of 12 with acetonitrile yields the nitrile complex {[(o,o′-C6F4C6F4Hg)4](MeCN)2} (15), which also forms infinite polymeric chains in the crystal. In each monomeric unit of the chain, the corresponding bridging nitrile is bonded to only one mercury atom of the anticrown moiety, whereas the other nitrile ligand is coordinated with two Hg sites. The synthesis and structure of the complex {[(o,o′-C6F4C6F4Hg)4](Me2CO)2(H2O)} (16), containing two acetone and one water ligand per molecule of 12, are also reported. Each acetone molecule in 16 interacts with only one Hg atom of 12, while the water molecule is coordinated with two mercury centers and, in addition, forms H-bonds with the oxygen atoms of the acetone species.

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INTRODUCTION Anticrowns constitute an important class of anion receptors and catalysts (see, e.g., reviews 1−7 and papers cited in refs 8−35). They contain several Lewis acidic centers in the chain of a macrocycle and so are able to cooperatively coordinate © XXXX American Chemical Society

various anionic and neutral Lewis basic species with the formation of complexes of unique structures. The highest Received: April 24, 2017

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DOI: 10.1021/acs.organomet.7b00315 Organometallics XXXX, XXX, XXX−XXX

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Organometallics Chart 1. Mercury-Containing Anticrowns

efficiency is displayed by polymercuramacrocycles with electron-accepting perfluorohydrocarbon and o-carborane backbones (see, e.g., macrocycles 1−8 in Chart 1). Despite the considerable progress achieved in the last two decades in this area, its further development is hampered by an insufficiently wide range of available anticrowns. In this context, the data of Massey and co-workers, published in the 1980s,36,37 are of considerable interest. The authors have described in their papers the synthesis of the previously unknown octafluoro-o,o′biphenylenemercury by the interaction of HgCl2 with o,o′dilithiooctafluorobiphenyl in ether and ascribed the cyclic trimeric structure (o,o′-C6F4C6F4Hg)3 (2) (Chart 1) to this compound on the basis of its mass spectra. However, the determination of the molecular weight of the synthesized organomercurial by an osmometric method in benzene gave a value corresponding to the tetramer rather than the trimer, and so its actual structure remained unclear for a long time. In our recent study,32 the aforementioned mercuracycle was transformed into o-xylene and acetonitrile complexes formulated as {[(o,o′-C 6 F 4 C 6 F 4 Hg) 3 ](o-Me 2 C 6 H 4 ) 2 } (9) and {[(o,o′C6F4C6F4Hg)3](MeCN)3} (10), respectively, on the basis of elemental analysis, and an X-ray diffraction study of these adducts has shown that 2 indeed has a cyclic trimeric structure. In the present paper, we report on the formation of one more organomercury compound, viz., the lithium chloride complex Li{[(o,o′-C6F4C6F4Hg)4]Cl} (11) of four-mercury anticrown (o,o′-C6 F4C 6F 4Hg)4 (12) (Chart 2), in the aforementioned reaction of o,o′-dilithiooctafluorobiphenyl with HgCl2 in ether. The transformations of 11 into free

Chart 2. Perfluorinated Four-Mercury Anticrown (o,o′C6F4C6F4Hg)4

mercuracycle 12 and its o-xylene, acetonitrile, and acetone complexes are also described.

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RESULTS AND DISCUSSION The interaction of HgCl2 with o,o′-dilithiooctafluorobiphenyl in ether results in the formation of a yellowish solution containing the aforementioned three-mercury macrocycle 2 as the main product and a white precipitate representing, as was found (see below), a mixture of lithium chloride and its complex 11 with four-mercury macrocycle 12. For the isolation of this chloride complex 11 in an individual state, the above precipitate was B

DOI: 10.1021/acs.organomet.7b00315 Organometallics XXXX, XXX, XXX−XXX

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Figure 1. ORTEP representation of two views of the anionic part of complex 13 with thermal ellipsoids drawn at the 50% probability level. Selected bond lengths (Å) and angles (deg): Hg(1)−Cl(1) 2.9221(14), Hg(2)−Cl(1) 2.9538(15), Hg(3)−Cl(1) 2.9330(15), Hg(4)−Cl(1) 3.0205(15); C(1)−Hg(1)−C(43) 166.1(2), C(7)−Hg(2)−C(13) 167.0(2), C(19)−Hg(3)−C(25) 166.1(2), C(31)−Hg(4)−C(37) 169.2(2).

in the cycle, the Hg−Cl distances are 2.944(2) Å.41 The chloride anion in this adduct is disposed in the plane formed by the mercury centers and is also bound to all of them. The Hg− Cl separations in the double-decker sandwich complexes of chloride anion with macrocycles 1 and 5 are in the ranges 3.035(1)−3.193(3) Å (average 3.10 Å)33 and 3.146(6)− 3.177(5) Å (average 3.16 Å),42 respectively, and in the bipyramidal dichloride complex of macrocycle 3 they are 3.089(6)−3.388(8) Å (average 3.25 Å).43 The Hg−Cl bond length in crystalline HgCl2 is equal to 2.25 Å.44 For polytinbased Lewis acids complexing chloride anions, see refs 45−47. The C−Hg−C bond angles in 13, in contrast to those in macrocycle 1 and its complexes,1,3−5 deviate markedly from 180° and range from 166.1(2) to 169.2(2)° (average 167.1(2)°). The Hg atoms in the complex lie at the corners of a somewhat distorted rectangle with sides Hg(1)···Hg(2) 4.0465(4) Å, Hg(2)···Hg(3) 3.9195(4) Å, Hg(3)···Hg(4) 4.2219(4) Å, and Hg(1)···Hg(4) 3.9276(4) Å and internal angles of 87.88(1)−91.99(1)°. Because complex 13, like macrocycle 2, is chiral, each of its molecules in the centrosymmetric unit cell (space group P1̅) is present as two enantiomers. The countercation in 13 is a sandwich complex of a lithium cation with two molecules of 12-crown-4. However, the structure of this sandwich is strongly disordered, and so it can not be discussed in detail. Further studies have shown that the stirring of the aforementioned lithium chloride complex 11·nMeCN with water at room temperature results in its gradual decomposition to form free four-mercury macrocycle 12 in 25% yield after 6 h according to 19F NMR spectra. An increase in temperature increases the rate of the process, and when the reaction is carried out with boiling water, nearly quantitative (95−97%) transformation of 11·nMeCN into 12 is reached even after 1 h. The 19F NMR spectrum of macrocycle 12 (obtained by such a way) in acetone-d6 contains four signals of equal intensity at δ −120.0, −137.1, −154.4, and −155.1 ppm as well as weak signals of the unreacted 11·nMeCN. In contrast to 11·nMeCN, complex 13 virtually does not react with water at room temperature for at least 7 h (the yield of 12 is no more than 1−

washed with acetonitrile, after which the resulting acetonitrile solution was evaporated under vacuum to dryness and the solid residue, representing the acetonitrile solvate 11·nMeCN according to IR spectra (ν(CN) 2283 (vw) and 2245 (vw) cm−1), was dissolved in ethanol. The subsequent addition of 12-crown-4 to the obtained ethanol solution led to the deposition of colorless crystals of the chloride complex [Li(12-crown-4)2]{[(o,o′-C6F4C6F4Hg)4]Cl} (13) containing one chloride anion per one molecule of the four-mercury macrocycle 12 according to elemental analysis. The yield of 13 is 37% (based on the starting o,o′-dibromooctafluorobiphenyl). An additional amount of the complex (4%) was obtained from the filtrate after separation of the main part of 13 (see the Experimental Section). The overall yield of complex 13 is 41%. The room-temperature 199Hg NMR spectrum of the isolated 13 in acetone-d6 ([13]0 = 4 × 10−2 mol L−1) exhibits a triplet at δ −27 ppm (relative to external Ph2Hg in Py) due to the coupling of the 199Hg nucleus (natural abundance 16.84%) with the o-fluorine atoms of two neighboring C6F4 units (3JHg−F = 475 Hz). The 19F NMR spectrum of the complex in acetone-d6 ([13]0 = 1.5 × 10−2 mol L−1) is identical with that of the initial white precipitate not purified from LiCl (see above) and shows four signals of equal intensity at δ −122.6, −139.2, −155.5, and −158.0 ppm (relative to external CFCl3). Thus, the second organomercury product of the reaction of HgCl2 with o,o′dilithiooctafluorobiphenyl before the addition of 12-crown-4 is indeed the complex of macrocycle 12 with lithium chloride, viz., Li{[(o,o′-C6F4C6F4Hg)4]Cl} (11). Figure 1 shows the structure of the anionic part of complex 13. The chloride anion in 13 is arranged at a distance of 0.79 Å from the plane formed by four Hg atoms (deviations from the mean plane do not exceed 0.04 Å) and is coordinated with them in a η4 fashion. The Hg−Cl bond lengths in this fragment of the complex span the range 2.9221(14)−3.0205(15) Å (average 2.96 Å), and all of these separations are considerably shorter than the sum of the van der Waals radii of mercury (1.73−2.00 Å,38,39 2.1 Å40) and chlorine (1.8 Å40) atoms. In the previously described 1:1 complex of chloride anion with ocarboranylmercury anticrown 6, also containing four Hg atoms C

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Figure 2. View of a fragment of an infinite chain of complex 14 in its crystal structure. The hydrogen atoms of the o-xylene molecules are omitted for clarity. Selected bond lengths (Å): Hg(1)−C(4S) 3.698(7), Hg(1)−C(5S) 3.226(6), Hg(1)−C(6S) 3.385(6), Hg(3A)−C(2S) 3.660(6), Hg(3A)− C(3S) 3.642(6), Hg(3A)−C(4S) 3.774(7), Hg(4)−C(13S) 3.791(7).

2%) and at 100 °C the yield of 12 after 1 h does not exceed 15%. That compound 12 indeed represents the free four-mercury anticrown (o,o′-C6F4C6F4Hg)4 is confirmed by its transformation into the o-xylene complex {[(o,o′-C6F4C6F4Hg)4](o-Me2C6H4)2} (14) on recrystallization of 12 from o-xylene. According to elemental analysis, the complex contains two oxylene molecules per molecule of the anticrown. The roomtemperature 199Hg NMR spectrum of 14 in THF ([14]0 = 4 × 10−2 mol L−1) shows a triplet at δ −48 ppm (3JHg−F = 440 Hz). The IR spectrum of the complex (as a Nujol mull) exhibits two aromatic out-of-plane C−H deformation bands at 763 (m) and 740 (m) cm−1, one of which (at 763 cm−1) is shifted by 23 cm−1 to a high-frequency region relative to the analogous band of uncoordinated o-xylene. The C−H stretching vibrations of the o-xylene ligands in the spectrum of 14 (hexachlorobutadiene mull) are observed as a set of 9 ν(C−H) bands at 3157 (w), 3107 (w), 3069 (w), 3018 (w), 2927 (m), 2881 (w), 2859 (w), 2781 (w), and 2737 (w) cm−1. The IR spectrum of free oxylene shows 10 ν(C−H) bands at 3106 (w), 3065 (w), 3051 (w), 3018 (m), 2990 (sh), 2971 (m), 2941 (m), 2921 (m), 2878 (w), and 2862 (w) cm−1. An X-ray diffraction study of complex 14 has shown that it forms one-dimensional chain associates in the crystal. As seen from Figure 2, in each monomeric unit of the chain one oxylene molecule (C1S−C6S) is a bridging ligand, connecting two neighboring anticrown moieties, whereas the other (C9S− C14S) plays a role of a terminal ligand. It should be noted that both the bridging and terminal o-xylene ligands in 14 are coordinated only with one Hg center of the corresponding anticrown molecule and, as a consequence, only three of the four mercury atoms of every macrocycle unit take part in the complexation with o-xylene. Note also, like 13, complex 14 is chiral and its neighboring homochiral chains in the crystal differ from one another in the stereochemical R/S configuration of the mercuramacrocycles. The Hg−C bond distances in 14 between the mercury atoms and the aromatic carbon atoms of the o-xylene rings in the case of the bridging o-xylene ligands are significantly shorter (3.226(6)−3.774(7) Å; average 3.56 Å) than the analogous distances (3.791(7) Å) in the case of the terminal o-xylene ligands, and all of these separations are within the sum of the

van der Waals radii of mercury (see above) and carbon (1.7 Å40) atoms. An additional contribution to the bonding of the terminal o-xylene molecules with macrocycle 12 in complex 14 is made by a π-stacking interaction between the aromatic oxylene and neighboring tetrafluorophenylene rings (the dihedral angle between the mean planes of these rings is 8.1°, the intercentroid distance is 3.78 Å, and the shortest C···C distance involving one of the ipso-carbon atoms of o-xylene and one of the carbon atoms of the tetrafluorophenylene ring is 3.352(9) Å). The bridging o-xylene molecules in 14 are coordinated with the Hg centers of the anticrown in a η3 fashion, while the terminal o-xylene species are bonded to the Hg atoms of the macrocycle in a η1 fashion. In o-xylene complex 9, which also has a polymeric structure in the crystal, the Hg−Carom bond lengths span the range 3.182(10)− 3.749(10) Å.32 The complexes of arenes with macrocycle 1 are characterized by Hg−Carom bond distances equal to 3.189(15)−3.553(17) Å (see a review5 and references therein), and in the arene complexes with diarylmercurials Ar2Hg these separations are 3.097(3)−3.550(4) Å.48,49 The structure of macrocycle 12 in its o-xylene complex 14 differs markedly from that of 12 in the chloride complex 13. Thus, the C−Hg−C bond angles in 14, in contrast to the corresponding angles in 13, are close to 180° (173.4(2)− 176.8(2)°; average 175.1(2)°). As in 13, the Hg atoms in each macrocyclic fragment of complex 14 are coplanar (deviations from the mean plane do not exceed 0.05 Å); however, in contrast to 13, they form here not a rectangle but a nearly perfect parallelogram with sides Hg(1)···Hg(2) 3.4349(3) Å, Hg(2)···Hg(3) 5.2821(3) Å, Hg(3)···Hg(4) 3.3407(3) Å, and Hg(1)···Hg(4) 5.2844(3) Å and internal angles equal to ca. 110 and 70°. Thermal decomposition of 14 at 100−120 °C under vacuum for 3 h leads to quantitative removal of o-xylene from the complex and to the formation of analytically pure free macrocycle 12 as an air-stable white powder readily soluble at room temperature in ethanol, THF, and ether, moderately soluble in acetone and CH2Cl2, and practically insoluble in nhexane, aromatic hydrocarbons, and acetonitrile. The IR spectrum of 12 is similar on the whole to that of 2, but the bands characteristic of the aromatic C−F bonds are shifted in the case of 12 by 2−4 cm−1 to a high-frequency region. In D

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Organometallics addition, the weak bands at 1609, 1285, and 800 cm−1, which are observed in the IR spectrum of 2, disappear in the spectrum of 12. The 19F NMR spectrum of macrocycle 12 (obtained from 14) in acetone-d6 does not differ in its parameters from the spectrum of crude 12 (obtained by the reaction of 11·nMeCN with boiling water) and displays four signals of equal intensity (at δ −120.0, −137.1, −154.4, and −155.1 ppm) which can be assigned to the F(1), F(4), F(2), and F(3) atoms, respectively (see Chart 3).

of uncoordinated acetonitrile (2254 cm−1). The room-temperature 199Hg NMR spectrum of 15 in THF ([15]0 = 4 × 10−2 mol L−1) shows a broadened triplet at δ −52 ppm (3JHg−F = 450 Hz), which is shifted by 6 ppm upfield relative to the corresponding signal of free macrocycle 12 (δ −46 ppm). In the presence of a 40-fold excess of acetonitrile, this triplet signal of 15 is shifted still further upfield and is observed at δ −78 ppm (3JHg−F = 435 Hz), thus indicating the existence of an equilibrium in the THF solution between 15 and macrocycle 12 not containing the coordinated nitrile species. The roomtemperature 19F NMR spectrum of 15 in acetone-d6 is practically identical with the corresponding spectra of 12 and 14. In the crystal, complex 15, like 14, forms one-dimensional chain associates (see Figure 3). In each monomeric unit of the associate, one of the two nitrile ligands, viz., H3C(2S)C(1S)N(1), is situated inside the cavity of the macrocycle and is bonded by its nitrogen atom to two Hg atoms, whereas the other nitrile, H3C(4S)C(3S)N(2), interacting with two adjacent polymercuramacrocycles, serves as a bridging ligand. Thus, in complex 15, in contrast to 14, all Hg centers of the anticrown moiety are involved in the bonding to the molecules of a Lewis base. As in 14, the neighboring homochiral chains in the crystal of 15 differ from each other in the stereochemical R/ S configuration of the mercuramacrocycles. The geometry of the coordinated acetonitrile molecules in complex 15 is close to linear; however, the Hg−N−C fragments in 15 deviate strongly from linearity (the corresponding Hg−N−C angles are in the range 120.0(6)− 123.9(6)°). The Hg−N bond distances in the complex range from 3.111(7) to 3.162(6) Å and are significantly shorter than the sum of the van der Waals radii of mercury (see above) and nitrogen (1.6 Å40) atoms. In the previously described acetonitrile complexes {[(o-C6F4Hg)3](MeCN)2},50 {[(oC2B10H10Hg)3](MeCN)3},51 {[(o-C2B10H10Hg)3](MeCN)5},51 and {[(o-C2B10H8Me2Hg)3](MeCN)3}52 of anticrowns 1, 4, and 5, the Hg−N separations span the range 2.74(3)−3.13(2) Å. All of these complexes contain at least one fragment wherein the nitrile ligand is η3 coordinated with the Hg centers of the anticrown. In the acetonitrile complex {[(o,o′-C6F4C6F4Hg)3](MeCN)3} of macrocycle 2, each of the nitrile species is η1

Chart 3. Atom-Numbering Scheme

The 199Hg NMR spectrum of 12 in THF virtually coincides with that of o-xylene complex 14 in the same solvent, which is, apparently, due to the displacement of the o-xylene ligands from the coordination sphere by THF molecules. In acetone-d6, the signal of the 199Hg resonance in the NMR spectrum of 12 represents a triplet of triplets at δ −80 ppm (3JHg−F = 440 Hz; 4 JHg−F = 100 Hz), shifted by 34 ppm upfield relative to the appropriate signal in the spectrum of 12 in THF. This result suggests that in the acetone solution macrocycle 12 is in the form of an acetone complex. Correspondingly, one may conclude that in the THF medium macrocycle 12 is present, probably, as a complex with THF. The tetrameric structure of mercuracycle 12 is also evidenced by an X-ray diffraction study of its acetonitrile complex {[(o,o′C6F4C6F4Hg)4](MeCN)2} (15). The complex is formed as colorless crystals in 69% isolated yield on dissolution of 12 (obtained from 14) in boiling acetonitrile followed by a slow cooling of the resulting solution to room temperature. According to elemental analysis, the obtained compound contains two acetonitrile molecules per molecule of fourmercury macrocycle 12. The IR spectrum of 15 exhibits four weak ν(CN) bands at 2293, 2252, 2248, and 2244 cm−1, shifted to low- and high-frequency regions relative to the ν(CN) band

Figure 3. View of a fragment of an infinite chain of complex 15 in its crystal structure. Selected bond lengths (Å) and angles (deg): Hg(1)−N(1) 3.156(7), Hg(3)−N(1) 3.111(7), Hg(4)−N(2) 3.124(6), Hg(2A)−N(2) 3.162(6), C(1S)−N(1) 1.114(10), C(3S)−N(2) 1.122(9); Hg(1)− N(1)−C(1S) 120.0(6), Hg(3)−N(1)−C(1S) 123.6(6), Hg(4)−N(2)−C(3S) 123.9(6), Hg(2A)−N(2)−C(3S) 123.6(6). E

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Organometallics bound to the molecule of 2 (the Hg−N distances are 2.778(7)−3.153(12) Å).32 The four Hg atoms in every macrocyclic unit of 15, as in complex 14, form a parallelogram close in its geometrical parameters (Hg(1)···Hg(2) 3.3515(4) Å, Hg(2)···Hg(3) 5.3014(4) Å, Hg(3)···Hg(4) 3.3476(4) Å, Hg(1)···Hg(4) 5.2821(4) Å; internal angles are ca. 108 and 72°) to those in 14. However, in contrast to 14, all Hg atoms of the chain of 15 in the crystal lie in one and the same plane (deviations from the mean plane do not exceed 0.03 Å). Note also that the nitrile molecules in each of these chains are arranged virtually in parallel to one another and perpendicularly to this plane. The C−Hg−C bond angles in 15 deviate from 180° somewhat more strongly than in 14 and span the range 170.3(2)− 174.4(2)° (average 172.4°). The aforementioned suggestion that in the acetone solution macrocycle 12 is present in the form of an adduct with the solvent is supported by the isolation of the bis-acetone complex {[(o,o′-C6F4C6F4Hg)4](Me2CO)2(H2O)} (16), also containing one coordinated water molecule, from the reaction of 12 with acetone. The complex was obtained in 89% isolated yield as a colorless crystalline solid representing an acetone solvate: 16· Me2CO. The source of the water molecules in the complex is evidently traces of moisture in the system. The roomtemperature 199Hg NMR spectrum of 16·Me2CO in THF ([16·Me2CO]0 = 4 × 10−2 mol L−1) exhibits a triplet signal at δ −49 ppm, shifted upfield only by 3 ppm relative to the appropriate signal of 12 in the same solvent. However, in the presence of an excess of acetone with respect to 16·Me2CO (40:1), the value of this upfield shift of the 199Hg resonance increases to 9 ppm. An X-ray diffraction study of complex 16·Me2CO has shown that, in contrast to 14 and 15, it has a discrete structure in the crystal (see Figure 4). The complex occupies a special position on a 2-fold crystal axis passing through the oxygen atom of the water molecule and the centers of the C(14)−C(14A) and C(20)−C(20A) bonds. The Hg atoms in 16, as in 13, form a rectangle (internal angles are 89.8 and 90.2°) but of somewhat

greater size (Hg(1)···Hg(1A) 3.9011(3) Å, Hg(1A)···Hg(2A) 5.4927(2) Å, Hg(2A)···Hg(2) 3.9327(3) Å, Hg(1)···Hg(2) 5.4927(2) Å) than in the case of 13. The acetone molecules in 16 are disposed above and below the plane formed by the mercury atoms, and each of these molecules is coordinated by its oxygen atom only with one Hg center. The Hg−O bond lengths in this fragment of the complex are equal to 3.092(4) Å and are considerably shorter than the sum of the van der Waals radii of mercury (see above) and oxygen (1.54 Å40) atoms. In contrast to the acetone oxygen atoms, the oxygen atom of the water molecule in 16 is located in the plane of the mercury rectangle and is bonded to two of its Hg centers (the Hg−O distances are 2.807(3) Å). An additional bonding of the molecule of H2O in 16 is due to the involvement of both of its protons in the formation of H bonds with the oxygen atoms of the acetone species (O(1W)−H(1W)···O(1S) 1.89 Å, O(1W)···O(1S) 2.789(4) Å, O(1W)−H(1W)···O(1S) 174°). The C−Hg−C bond angles in 16, as in 14, are close to 180° (C(1)−Hg(1)−C(19) 177.26(17)°, C(13)−Hg(2)−C(7) 175.58(18)°). Interestingly, in contrast to 13−15, the unit cell of the crystal selected for the X-ray diffraction study of 16 (chiral space group C2221) contains only one of two its enantiomers, namely, the R enantiomer, thus indicating a spontaneous chiral resolution during the crystallization. The mixed acetone−water complex {[(o-C2B10H10Hg)3](Me2CO)3(H2O)} was also previously described for ocarboranylmercury anticrown 4.53 The water molecule in this complex is bound via the oxygen atom to all three Hg centers of 4 (the Hg−O bond lengths are 2.915(5) Å), whereas the carbonyl oxygen atom of each acetone ligand is coordinated with a single Hg site (the Hg−O distances are 2.762(4) Å). In contrast to 16, all four Lewis basic guests in this adduct are disposed on one side of the metallacycle plane. In the 1:1 acetone complex {[(o-C6F4Hg)3](Me2CO)}, containing a η3coordinated acetone molecule, the Hg−O separations span the range 2.810(12)−2.983(12) Å,54 while in the complex {[(oC6F4Hg)3](Me2CO)3}, containing two η3- and one η1coordinated acetone species, these separations range from 2.813(6) to 3.088(8) Å.55

Figure 4. ORTEP representation of the molecular structure of complex 16 with thermal ellipsoids drawn at the 30% probability level. The hydrogen atoms of the acetone molecules are omitted for clarity. Selected bond lengths (Å): Hg(1)−O(1W) 2.807(3), Hg(2)−O(1S) 3.092(4), H(1W)···O(1S) 1.89, C(1S)−O(1S) 1.222(6).

CONCLUSION Thus, the interaction of o,o′-dilithiooctafluorobiphenyl with HgCl2 in ether results in the formation of two organomercury products. One of them, described earlier in refs 32, 36, and 37, is the perfluorinated three-mercury anticrown 2. The other product, revealed in the present study, is the lithium chloride complex 11 of four-mercury anticrown 12. The complex was identified by its transformation into [Li(12-crown-4)2]{[(o,o′C6F4C6F4Hg)4]Cl} (13) under the action of 12-crown-4 and the structure determination of the resulting adduct. According to X-ray crystallography, the chloride anion in 13 is cooperatively coordinated by all four Hg centers of the anticrown. The analytically pure free anticrown 12 can be prepared by the reaction of 11 as an acetonitrile solvate with boiling water followed by the recrystallization of the obtained crude 12 from o-xylene and the thermal decomposition of the resulting o-xylene complex 14 at 100−120 °C under vacuum. An X-ray diffraction study of 14 as well as of the corresponding acetonitrile and acetone−water complexes 15 and 16, synthesized in this work, confirms the tetrameric structure of macrocycle 12. It should be noted that the geometry of this macrocycle significantly changes on transition from 13 to 14 and then to 16, thus indicating its structural nonrigidity. The

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obtained crude 12 from o-xylene gave colorless crystals of complex 14, which was dried under vacuum at 20 °C for 2 h. Yield of 14: 0.434 g. Anal. Calcd for C64H20F32Hg4: C, 34.95; H, 0.92; F, 27.64. Found: C, 34.81; H, 1.01; F, 27.58. 19F NMR (acetone-d6, δ, ppm): −120.0 (dd with satellites, 3JF−Hg = 435 Hz, 1F), −137.1 (m, 1F), −154.4 (dd, 1F), −155.1 (m, 1F). 199Hg NMR (THF, δ, ppm): −48 (t, 3JHg−F = 440 Hz). IR (cm−1): 3157 (w), 3107 (w), 3069 (w), 3018 (w), 2927 (m), 2881 (w), 2859 (w), 2781 (w), 2737 (w), 1629 (m), 1609 (w), 1594 (m), 1495 (m), 1489 (m), 1467 (m), 1450 (m), 1438 (m), 1304 (m), 1273 (w), 1121 (w), 1100 (s), 1062 (s), 1016 (s), 932 (m), 814 (m), 796 (w), 779 (w), 763 (m), 740 (m), 709 (m). Single crystals of 14 suitable for X-ray diffraction study were not dried under vacuum. Thermal Decomposition of {[(o,o′-C 6 F 4 C 6 F 4 Hg) 4 ](oMe2C6H4)2} (14). Complex 14 (0.220 g, 0.1 mmol) was heated under vacuum (5 × 10−2 mm Hg) at 120 °C for 2 h to give a white powder of free macrocycle 12. Yield: 0.198 g (ca. 100%). Anal. Calcd for C48F32Hg4: C, 29.02; F, 30.60. Found: C, 28.86; F, 30.27. 19F NMR (acetone-d6, δ, ppm): −120.0 (dd with satellites, 3JF−Hg = 440 Hz, 1F), −137.1 (m, 1F), −154.4 (dd, 1F), −155.1 (m, 1F). 199Hg NMR (THF, δ, ppm): −46 (t, 3JHg−F = 440 Hz). 199Hg NMR (acetone-d6, δ, ppm): −80 (tt, 3JHg−F = 440 Hz, 4JHg−F = 100 Hz). IR (cm−1): 1628 (m), 1593 (m), 1495 (s), 1469 (s), 1451(s), 1439 (sh), 1304 (m), 1271 (w), 1100 (s), 1062 (s), 1018 (s), 934 (m), 814 (m), 797 (w), 778 (w), 708 (m). Synthesis of {[(o,o′-C6F4C6F4Hg)4](MeCN)2} (15). A 0.1987 g amount (0.1 mmol) of macrocycle 12 (prepared from 14) was dissolved in 50 mL of boiling acetonitrile, and the obtained solution was cooled gradually to room temperature. In the course of cooling, small colorless crystals of complex 15 were formed on the bottom and the walls of the vessel. The next day, the precipitated crystals of 15 were filtered off, washed with MeCN (2 × 0.5 mL), and dried at 20 °C under vacuum for 1.5 h. Yield of 15: 0.1417 g (69%). Anal. Calcd for C52H6N2F32Hg4: C, 30.19; H, 0.29; F, 29.38. Found: C, 30.20; H, 0.32; F, 28.94. 19F NMR (acetone-d6, δ, ppm): −120.0 (dd with satellites, 3 JF−Hg = 445 Hz, 1F), −137.1 (m, 1F), −154.4 (dd, 1F), −155.1 (m, 1F). 199Hg NMR (THF, δ, ppm): −52 (t, 3JHg−F = 450 Hz). IR (cm−1): 3164 (vw), 2947 (w), 2293 (w), 2252 (w), 2248 (w), 2244 (w), 1627 (m), 1592 (m), 1498 (s), 1487 (s), 1471 (s), 1460 (s), 1446 (s), 1433 (s), 1375 (m), 1302 (m), 1273 (w), 1097 (s), 1061 (s), 1020 (m), 1011 (m), 933 (m), 810 (m), 708 (m). For the X-ray diffraction study, the crystals of 15 were not washed and were not dried under vacuum. Synthesis of {[(o,o′-C6F4C6F4Hg)4](Me2CO)2(H2O)}·Me2CO (16· Me2CO). A 0.0990 g amount (0.05 mmol) of macrocycle 12 (prepared from 14) was dissolved in 5 mL of hot acetone, after which the obtained solution was cooled to room temperature and allowed to slowly evaporate to 1 mL for 6 days. Then, the precipitated colorless crystals were filtered off, washed with acetone (2 × 0.5 mL), and dried at 20 °C under vacuum for 1 h. Yield of 16·Me2CO: 0.0966 g (89%). Anal. Calcd for C57H20O4F32Hg4: C, 31.42; H, 0.93; F, 27.90. Found: C, 31.53; H, 1.10; F, 27.95. 199Hg NMR (THF, δ, ppm): −49 (t, 3JHg−F = 430 Hz). IR (cm−1): 3382 (br), 3372 (br), 1691 (m), 1625 (m), 1610 (sh), 1591 (m), 1302 (m), 1270 (w), 1101 (s), 1064 (s), 1015 (s), 932 (m), 815 (m), 709 (m). For the X-ray diffraction study, the crystals of 16·Me2CO were not washed and were not dried under vacuum. X-ray Diffraction Study. Single-crystal X-ray diffraction experiments were carried out with a Bruker SMART APEX II diffractometer (graphite-monochromated Mo Kα radiation, λ = 0.71073 Å, ω-scan technique). APEX II software57 was used for collecting frames of data, indexing reflections, determination of lattice constants, integration of intensities of reflections, scaling, and absorption correction, and SHELXTL58 was applied for space group and structure determination, refinements, graphics, and structure reporting. The structures were solved by direct methods and refined by the full-matrix least-squares technique against F2 with anisotropic thermal parameters for all nonhydrogen atoms. The hydrogen atoms were placed geometrically and included in the structure factor calculations in the riding motion approximation. A Flack parameter59 (x = 0.003(3)) was used to estimate the absolute configuration of complex 16 in the crystal.

synthesis of 12 widens the range of the presently known perfluorinated mercury-containing anticrowns.

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EXPERIMENTAL SECTION

Commercial o,o′-dibromooctafluorobiphenyl (P&M-Invest; 99%), mercury dichloride (Aldrich; 99.5%), n-butyllithium (Aldrich; 1.6 M solution in hexanes), and 12-crown-4 (Fluka; 99%) were used without additional purification. Solvents were purified by conventional methods and freshly distilled prior to use over LiAlH4 (diethyl ether, THF), metallic sodium (n-hexane, o-xylene), or calcium hydride (ethanol, acetonitrile) under Ar. The 199Hg NMR spectra were recorded on a Bruker Av-600 instrument using a 0.2 M solution of Ph2Hg in pyridine (δ −791.1 ppm56) as an external standard. The 19F NMR spectra were registered on a Bruker Av-400 instrument using CFCl3 as an external standard. Assignment of the 19F NMR signals was done on the basis of homonuclear chemical shift correlation (COSY) experiments for 2.32 The IR spectra were recorded as Nujol and hexachlorobutadiene mulls on a Bruker Tensor 37 Fourier spectrometer. Synthesis of [Li(12-crown-4)2]{[(o,o′-C6F4C6F4Hg)4]Cl} (13). A solution of n-butyllithium (13.8 mL, 22.0 mmol) in hexanes was added dropwise for 20 min to a stirred solution of o,o′-dibromooctafluorobiphenyl (5.07 g, 11.0 mmol) in diethyl ether (100 mL) at −78 °C under Ar, and the resulting mixture was stirred for 1 h at −78 °C under an Ar atmosphere. Then, the mixture was treated with solid HgCl2 (2.99 g, 11.0 mmol) and warmed to room temperature with strong stirring. After 1 h, the resulting yellowish solution, containing a white precipitate, was filtered off and the precipitate, representing a mixture of complex 11 and LiCl, was washed with an Et2O/n-hexane (7/1) mixture (3 × 8 mL) under Ar and dried under vacuum at room temperature for 2 h. The obtained yellowish filtrate, containing only very small amounts of 11, can be used further for the preparation of complex 9 and free macrocycle 2 according to the previously published procedures,32 whereas the precipitate was applied to the synthesis and isolation of complex 13 and free macrocycle 12. For the synthesis of 13, the precipitate was stirred in 20 mL of acetonitrile for 30 min under an Ar atmosphere and the residual insoluble LiCl was filtered off and washed with acetonitrile (3 × 2 mL) under Ar, after which the filtrate was evaporated under vacuum and the yellowish solid residue, representing the acetonitrile solvate 11· nMeCN, was dried for 4 h at 20 °C. Then, to the resulting 11·nMeCN, dissolved in 10 mL of hot ethanol, was added 1.0 mL of 12-crown-4 and the obtained mixture was allowed to evaporate at 20 °C to 4 mL. The next day, the precipitated white crystalline powder of complex 13 was filtered off, washed with cold ethanol (3 × 1 mL), and dried under vacuum for 4 h. Yield of 13: 2.44 g (37%). A slow concentration of the resulting filtrate to 1.0 mL at 20 °C gave an additional 0.26 g (4%) of 13 as crystals suitable for an X-ray diffraction study. Overall yield of 13: 2.70 g (41%). Anal. Calcd for C64H32LiO8F32ClHg4: C, 32.26; H, 1.35; F, 25.53. Found: C, 31.86; H, 1.36; F, 25.20. 19F NMR (acetoned6, δ, ppm): −122.6 (dd with satellites, 3JF−Hg = 472 Hz, 1F), −139.2 (m, 1F), −155.5 (dd, 1F), −158.0 (m, 1F). 199Hg NMR (acetone-d6, δ, ppm): −27 (t, 3JHg−F = 475 Hz). IR (Nujol mull, cm−1): 1628 (m), 1605 (w), 1590 (m), 1491 (s), 1447 (s), 1367 (m), 1301 (m), 1269 (w), 1247 (w), 1138 (m), 1100 (s), 1092 (s), 1057 (s), 1027 (m), 1013 (s), 929 (m), 858 (w), 813 (w), 792 (w), 774 (w), 706 (m), 639 (w), 615 (w), 596 (w), 559 (w), 530 (w), 505 (w), 478 (w). Synthesis of {[(o,o′-C6F4C6F4Hg)4](o-Me2C6H4)2} (14). In another experiment, a part (0.595 g) of the aforementioned yellowish complex 11·nMeCN, obtained after workup of the reaction mixture formed in the interaction of HgCl2 (2.99 g, 11.0 mmol) with the corresponding amount of o,o′-dilithiooctafluorobiphenyl, was vigorously stirred in boiling distilled water (8 mL) for 1 h. In the course of the reaction, an almost complete disappearance of the starting 11· nMeCN was observed according to 19F NMR spectra. Then, the solid phase, representing crude free macrocycle 12, was separated by filtration, washed with distilled water (4 × 2 mL), and dried under vacuum at 120 °C for 3 h. The 19F NMR yield of 12 is 96% (based on the starting 11·nMeCN). The subsequent recrystallization of the G

DOI: 10.1021/acs.organomet.7b00315 Organometallics XXXX, XXX, XXX−XXX

Article

Organometallics

M.; Shubina, E. S. Izv. Akad. Nauk, Ser. Khim. 2008, 2489; Russ. Chem. Bull., Int. Ed. 2008, 57, 2540. (14) Tikhonova, I. A.; Tugashov, K. I.; Dolgushin, F. M.; Korlyukov, A. A.; Petrovskii, P. V.; Klemenkova, Z. S.; Shur, V. B. J. Organomet. Chem. 2009, 694, 2604. (15) Tikhonova, I. A.; Gribanyov, D. A.; Tugashov, K. I.; Dolgushin, F. M.; Smol’yakov, A. F.; Peregudov, A. S.; Klemenkova, Z. S.; Shur, V. B. Organometallics 2009, 28, 6567. (16) Filatov, A. S.; Jackson, E. A.; Scott, L. T.; Petrukhina, M. A. Angew. Chem., Int. Ed. 2009, 48, 8473. (17) Tikhonova, I. A.; Gribanyov, D. A.; Tugashov, K. I.; Dolgushin, F. M.; Peregudov, A. S.; Antonov, D. Yu.; Rosenberg, V. I.; Shur, V. B. J. Organomet. Chem. 2010, 695, 1949. (18) Semenov, N. A.; Bagryanskaya, I. Yu.; Alekseev, A. V.; Gatilov, Yu. V.; Lork, E.; Mews, R.; Roeschentaler, G.-V.; Zibarev, A. V. Zh. Strukt. Khim. 2010, 51, 569; J. Struct. Chem. 2010, 51, 552 (Engl. Transl.). (19) Muñoz-Castro, A.; Carey, D. M.; Arratia-Pérez, R. J. Phys. Chem. A 2010, 114, 666. (20) Tikhonova, I. A.; Gribanyov, D. A.; Tugashov, K. I.; Dolgushin, F. M.; Smol’yakov, A. F.; Peregudov, A. S.; Klemenkova, Z. S.; Shur, V. B. ARKIVOC 2011, 172. (21) Filatov, A. S.; Greene, A. K.; Jackson, E. A.; Scott, L. T.; Petrukhina, M. A. J. Organomet. Chem. 2011, 696, 2877. (22) Fleischmann, M.; Heindl, C.; Seidl, M.; Balázs, G.; Virovets, A. V.; Peresypkina, E. V.; Tsunoda, M.; Gabbaï, F. P.; Scheer, M. Angew. Chem., Int. Ed. 2012, 51, 9918. (23) Tikhonova, I. A.; Yakovenko, A. A.; Tugashov, K. I.; Dolgushin, F. M.; Petrovskii, P. V.; Minacheva, M. Kh.; Strunin, B. N.; Shur, V. B. Izv. Akad. Nauk, Ser. Khim. 2013, 710; Russ. Chem. Bull., Int. Ed. 2013, 62, 710. (24) Tugashov, K. I.; Gribanyov, D. A.; Dolgushin, F. M.; Smol'yakov, A. F.; Peregudov, A. S.; Minacheva, M. Kh.; Strunin, B. N.; Tikhonova, I. A.; Shur, V. B. J. Organomet. Chem. 2013, 747, 167. (25) Fisher, S. P.; Reinheimer, E. W. J. Chem. Crystallogr. 2013, 43, 478. (26) Fisher, S. P.; Reinheimer, E. W. J. Chem. Crystallogr. 2014, 44, 123. (27) Castañeda, R.; Draguta, S.; Yakovenko, A.; Fonari, M.; Timofeeva, T. Acta Crystallogr., Sect. E: Crystallogr. Commun. 2014, 70, m164. (28) Muñoz-Castro, A. Phys. Chem. Chem. Phys. 2014, 16, 7578. (29) Ponce-Vargas, M.; Muñoz-Castro, A. J. Phys. Chem. C 2014, 118, 28244. (30) Schmidbaur, H.; Schier, A. Organometallics 2015, 34, 2048. (31) Fisher, S. P.; Groeneman, R. H.; Reinheimer, E. W. J. Coord. Chem. 2015, 68, 3589. (32) Tugashov, K. I.; Gribanyov, D. A.; Dolgushin, F. M.; Smol'yakov, A. F.; Peregudov, A. S.; Tikhonova, I. A.; Shur, V. B. Organometallics 2015, 34, 1530. (33) Tugashov, K. I.; Gribanyov, D. A.; Dolgushin, F. M.; Smol'yakov, A. F.; Peregudov, A. S.; Minacheva, M. Kh.; Tikhonova, I. A.; Shur, V. B. Organometallics 2016, 35, 2197. (34) Tsunoda, M.; Fleischmann, M.; Jones, J. S.; Bhuvanesh, N.; Scheer, M.; Gabbaï, F. P. Dalton Trans. 2016, 45, 5045. (35) Lasanta, T.; López-de-Luzuriada, J. M.; Monge, M.; Olmos, M. E.; Pascual, D. Dalton Trans. 2016, 45, 6334. (36) Al-Jabar, N. A. A.; Massey, A. G. J. Organomet. Chem. 1984, 275, 9. (37) Massey, A. G.; Al-Jabar, N. A. A.; Humphries, R. E.; Deacon, G. B. J. Organomet. Chem. 1986, 316, 25. (38) Canty, A. J.; Deacon, G. B. Inorg. Chim. Acta 1980, 45, L225. (39) Pyykkö, P.; Straka, M. Phys. Chem. Chem. Phys. 2000, 2, 2489. (40) Batsanov, S. S. Zh. Neorg. Khim. 1991, 36, 3015. (41) Yang, X.; Knobler, C. B.; Hawthorne, M. F. Angew. Chem., Int. Ed. Engl. 1991, 30, 1507. (42) Lee, H.; Knobler, C. B.; Hawthorne, M. F. J. Am. Chem. Soc. 2001, 123, 8543.

Crystallographic data for complexes 13−16 are presented in Table 1S in the Supporting Information.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.organomet.7b00315. 19 F and 199Hg NMR spectra of isolated compounds, molecular structures of monomeric fragments of complexes 14 and 15, molecular structure of complex 16, and crystallographic data for complexes 13−16 (PDF) Accession Codes

CCDC 1549326−1549329 contain the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Author

*E-mail for V.B.S.: [email protected]. ORCID

Vladimir B. Shur: 0000-0001-8963-068X Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS This work was supported by the Russian Foundation for Basic Research (project code 16-03-00749). Structural studies were supported by the Ministry of Education and Science of the Russian Federation (A.F.S., Agreement No. 02.a03.21.0008).

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REFERENCES

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DOI: 10.1021/acs.organomet.7b00315 Organometallics XXXX, XXX, XXX−XXX