Complexation of [12] Crown-4,[18] Crown-6, and 1, 3, 5-Trioxane with

Oct 26, 2009 - From the interaction of 1 3 EtOH with 1,3,5-trioxane, a 1:1 complex, {[(o-C6F4Hg)3](CH2O)3}(7), having a cage structure, has been isola...
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Organometallics 2009, 28, 6567–6573 DOI: 10.1021/om900626j

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Complexation of [12]Crown-4, [18]Crown-6, and 1,3,5-Trioxane with Cyclic Trimeric Perfluoro-o-phenylenemercury. Synthesis and Structures of the First Complexes of Crown Ethers with an Anticrown Irina A. Tikhonova, Dmitry A. Gribanyov, Kirill I. Tugashov, Fedor M. Dolgushin, Alexandr F. Smol’yakov, Alexandr S. Peregudov, Zinaida S. Klemenkova, and Vladimir B. Shur* A.N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilov Street 28, 119991 Moscow, Russian Federation Received July 17, 2009

The reaction of anhydrous [12]crown-4 with a 1:1 ethanol adduct of the three-mercury anticrown (o-C6F4Hg)3 (1) under Ar results in the formation of a double-decker sandwich complex {[(oC6F4Hg)3]2([12]crown-4)} (4). The molecule of the crown ether in 4 is located between the mutually parallel planes of two mercury macrocycles and is coordinated to each of them through Hg-O secondary interactions. In the crown ether ligand, all four oxygen atoms are involved in the bonding to the molecules of 1, while in each anticrown species only two Hg centers take part in the coordination. If aqueous [12]crown-4 is used in the reaction with 1, the other double-decker sandwich, {[(o-C6F4Hg)3]2([12]crown-4)(H2O)2} (5), containing one crown ether molecule and two molecules of H2O in the space between the planes of the anticrown units, is produced. Every water molecule in this supramolecular aggregate is cooperatively bound through the oxygen atom by three Lewis acidic Hg sites of the neighboring anticrown, whereas one of the water protons forms the hydrogen bond with the oxygen atom of the crown ether. An additional contribution in the bonding is made by the interaction of one of the Hg centers of each anticrown unit with the nearest oxygen atom of [12]crown-4. The complex of analogous composition and close structure is formed in the reaction of 1 with aqueous [18]crown-6. However in this sandwich, {[(o-C6F4Hg)3]2([18]crown-6)(H2O)2} (6), both protons of each water species are involved in the formation of the H-bonds with the crown ether, while the bonding of each mercuramacrocycle to the crown ether is accomplished due to the coordination of two of its Hg atoms with two oxygen atoms of the crown compound. From the interaction of 1 3 EtOH with 1,3,5-trioxane, a 1:1 complex, {[(o-C6F4Hg)3](CH2O)3} (7), having a cage structure, has been isolated. The synthesized adducts are the first complexes of crown ethers with an anticrown.

Introduction Anticrowns1 represent charge-reversed analogues of crown ethers and related species. They contain several Lewis acidic centers in the macrocyclic chain and so exhibit a high affinity for various anions and neutral Lewis bases to form complexes of unprecedented structures (see, for example, reviews 2-8 and

recent papers cited in refs 9-14). Particularly efficient anticrowns have been found among polymercuramacrocycles with electron-withdrawing perfluorohydrocarbon2,4-6,8-14 and o-carborane3,8,15 backbones.

*Corresponding author. E-mail: [email protected]. (1) This term was first proposed by Hawthorne et al. in: Yang, X.; Zheng, Z.; Knobler, C. B.; Hawthorne, M. F. J. Am. Chem. Soc. 1993, 115, 193. (2) Shur, V. B.; Tikhonova, I. A. In Encyclopedia of Supramolecular Chemistry; Atwood, J. L.; Steed, J. W., Eds.; Marcel Dekker: New York, 2004; p 68. (3) Wedge, T. J.; Hawthorne, M. F. Coord. Chem. Rev. 2003, 240, 111. (4) Shur, V. B.; Tikhonova, I. A. Izv. Akad. Nauk, Ser. Khim. 2003, 2401 (Russ. Chem. Bull., Int. Ed. Engl. 2003, 52, 2539). (5) Haneline, M. R.; Taylor, R. E.; Gabbaı¨ , F. P. Chem.;Eur. J. 2003, 21, 5188. (6) Taylor, T. J.; Burres, C. N.; Gabbaı¨ , F. P. Organometallics 2007, 26, 5252. (7) Wuest, J. D. Acc. Chem. Res. 1999, 32, 81. (8) Hawthorne, M. F.; Zheng, Z. Acc. Chem. Res. 1997, 30, 267.

(9) Tikhonova, I. A.; Tugashov, K. I.; Dolgushin, F. M.; Yakovenko, A. A.; Petrovskii, P. V.; Furin, G. G.; Zaraisky, A. P.; Shur, V. B. J. Organomet. Chem. 2007, 692, 953. (10) Tikhonova, I. A.; Tugashov, K. I.; Dolgushin, F. M.; Petrovskii, P. V.; Shur, V. B. Organometallics 2007, 26, 5193. (11) Elbjeirami, O; Burress, C. N.; Gabbaı¨ , F. P.; Omary, M. A. J. Phys. Chem. C 2007, 111, 9522. (12) Taylor, T. J.; Elbjeirami, O; Burress, C. N.; Tsunoda, M.; Bodine, M. I.; Omary, M. A.; Gabbaı¨ , F. P. J. Inorg. Organomet. Polym. 2008, 18, 175. (13) Tsupreva, V. N.; Filippov, O. A.; Dolgushin, F. M.; Tugashov, K. I.; Krylova, A. I.; Bragin, V. I.; Tikhonova, I. A.; Shur, V. B.; Epstein, L. M.; Shubina, E. S. Izv. Akad. Nauk, Ser. Khim. 2008, 2487 (Russ. Chem. Bull., Int. Ed. Engl. 2008, 57 (12)). (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) Bayer, M. J.; Jalisatgi, S. S.; Smart, B.; Herzog, A.; Knobler, C. B.; Hawthorne, M. F. Angew. Chem., Int. Ed. 2004, 43, 1854.

r 2009 American Chemical Society

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Recently, we have reported on the ability of one such macrocycle, viz., cyclic trimeric perfluoro-o-phenylenemercury, (o-C6F4Hg)3 (1),16 to bind [9]thiacrown-3 and the simplest representative of thiacrowns, 1,3,5-trithiane.10 As a result of the reactions, complexes {[(o-C6F4Hg)3]([9]thiacrown-3)}, {[(o-C6F4Hg)3]2([9]thiacrown-3)} (2), and {[(oC6F4Hg)3](CH2S)3} (3) were produced. Especially interesting are complexes 2 and 3, having double-decker sandwich and cage structures, respectively. In these adducts, all three sulfur atoms of the thiacrown and all three Hg sites of the anticrown are involved in the complexation, thus impressively illustrating a charge-reversed analogy between crown compounds and anticrowns. In the present article, the synthesis and structures of complexes of 1 with [12]crown-4, [18]crown-6, and 1,3,5-trioxane are described in detail. The synthesized compounds are the first complexes of crown ethers with an anticrown.

Tikhonova et al.

species. Attempts to obtain an anhydrous complex of 1 with [18]crown-6 in an analytically pure state failed. The reaction of 1 with 1,3,5-trioxane proved to be insensitive to the presence of traces of moisture in the system. The experiments were carried out in dry CH2Cl2 and diethyl ether as solvents with the use of free 1 or its ethanol adduct 1 3 EtOH,14 which is considerably more soluble than 1 in these solvents. The interaction of 1 3 EtOH with an excess of anhydrous [12]crown-4 in dry diethyl ether at 22 °C under Ar results in precipitation of colorless crystals having the composition {[(o-C6F4Hg)3]2([12]crown-4)} (4) on the basis of elemental analysis. The IR spectrum of 4 in Nujol mull shows no ν(OH) bands, thus confirming the absence of water in the isolated product. The room-temperature 199Hg NMR spectrum of 4 in THF ([4]0=8  10-2 mol L-1) differs only insignificantly from the spectrum of 1 in the same solvent even in the presence of a large excess of [12]crown-4 (40:1), which indicates a practically quantitative displacement of the crown compound from the complex by THF molecules. An X-ray diffraction study of 4 has shown that the crown ether molecule in the complex is sandwiched by two mutually parallel anticrown units and is coordinated to each of them through Hg-O secondary interactions (Figure 1). In the crown ether ligand, all four oxygen atoms are involved in the bonding to the molecules of 1, whereas in each anticrown species, only two mercury centers take part in the coordination. One of these Hg centers interacts with two oxygen atoms of the crown ether and forms one comparatively short Hg-O contact (2.804(3) A˚; see Table 1) and one considerably longer Hg-O contact (3.493(3) A˚), which do, however,

Results and Discussion A commercial sample of [18]crown-6 (Reanal; 98%), which was used in our study, contains water, as evidenced by the presence in its IR spectrum of the broad ν(OH) bands at 3457 and 3398 (sh) cm-1. The introduction of an undried sample into the reaction with 1 leads to the involvement of water together with the starting crown ether in the complexation with the mercury anticrown. The IR spectrum of commercial [12]crown-4 (Fluka; 99%) shows no ν(OH) bands, and correspondingly, its reaction with 1 under Ar yields a complex containing only the crown ether as the Lewis basic guest. However, if commercial [12]crown-4 is held for 9-10 days in contact with air moisture, the broad ν(OH) bands at 3497 and 3280 (sh) cm-1 appear in the spectrum and, as a consequence, the resulting complex with 1 contains again the coordinated water and crown ether

Hg(1)-O(1) Hg(1)-O(2)

(16) (a) Sartori, P.; Golloch, A. Chem. Ber. 1968, 101, 2004. (b) Ball, M. C.; Brown, D. S.; Massey, A. G.; Wickens, D. A. J. Organomet. Chem. 1981, 206, 265.

C(1)-Hg(1)-C(14) C(2)-Hg(2)-C(7)

Figure 1. ORTEP representation of the molecular structure of complex 4 with thermal ellipsoids drawn at the 50% probability level. The hydrogen atoms of the crown ether are omitted for clarity. Table 1. Selected Bond Lengths (A˚) and Angles (deg) in Complex 4 Bond Lengths 2.804(3) 3.493(3)

Hg(2)-O(2)

3.083(3)

Bond Angles 174.17(18) 173.55(18)

C(8)-Hg(3)-C(13)

175.61(18)

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remain slightly shorter than the sum of the van der Waals radii of mercury (1.73-2.00 A˚,17a,b 2.1 A˚17c) and oxygen (1.54 A˚17d) atoms. The other Hg center in 4 coordinates with a single oxygen atom of [12]crown-4 (Hg-O 3.083(3) A˚). In the crystal, complex 4 forms extended stacks due to shortened (as compared to the sum of the van der Waals radii) intermolecular Hg 3 3 3 Hg (3.723(1) A˚) and Hg 3 3 3 C (3.411(5)-3.707(5) A˚) contacts between the neighboring molecules of the adduct. The stacks are disposed along the a crystal axis and are linked with each other through shortened intramolecular Hg 3 3 3 F contacts (3.167(3) and 3.239(3) A˚). The distance between the mean planes of the central Hg3C6 rings of the adjacent mercuramacrocycles in the stack is 3.36 A˚. The mutual orientation of these juxtaposed rings is close to a staggered conformation. The formation of similar stacks was earlier observed in the crystal structures of the double-decker sandwich complexes of 1 with closo-[B10H10]2-, closo-[B12H12]2-, closo-[B12H11SCN]2-, [Fe(CN)6]3-, and [Fe(CN)5(NO)]2- anions18-20 as well as with metallocenes,21,22 p-benzoquinone,23 and [9]thiacrown-3.10 When an excess of aqueous [12]crown-4 is used in the reaction with 1 in dry CH2Cl2 under Ar, a colorless crystalline complex formulated as {[(o-C6F4Hg)3]2([12]crown-4)(H2O)2} (5) is produced after slow concentration of the reaction solution to a small volume. The same complex 5 is formed in the interaction of 1 with anhydrous [12]crown-4 in dry CH2Cl2 in the presence of air moisture. The IR spectrum of 5 exhibits broad ν(OH) bands at 3362-3369 and 32343238 cm-1 as well as a sharp ν(OH) band at 3632 cm-1. The first two bands can be assigned to the vibrations of OH groups forming the hydrogen bonds with the coordinated [12]crown-4, while the third ν(OH) band can be attributed to the vibrations of OH groups not participating in the H-bonding. The room-temperature 199Hg NMR spectrum of complex 5 in THF ([5]0 = 8  10-2 mol 3 L-1) shows a downfield 199Hg shift of 3 ppm relative to that of free 1. On the addition of a 40-fold excess of aqueous [12]crown-4 to 5 in THF, the value of this downfield shift increases to 7 ppm. The structure of 5 is shown in Figure 2. The complex represents a double-decker sandwich containing one crown ether molecule and two molecules of H2O in the space between the mutually parallel planes of two anticrown moieties. Every water molecule in this supramolecular aggregate is cooperatively bound through the oxygen atom by (17) (a) Canty, A. J.; Deacon, G. B. Inorg. Chim. Acta 1980, 45, L225. (b) Pyykk€ o, P.; Straka, M. Phys. Chem. Chem. Phys. 2000, 2, 2489. (c) Batsanov, S. S. Zh. Neorg. Khim. 1991, 36, 3015. (d) Nyburg, S. C.; Faerman, C. H. Acta Crystallogr., Sect. B 1985, 41, 274. (18) Shubina, E. S.; Tikhonova, I. A.; Bakhmutova, E. V.; Dolgushin, F. M.; Antipin, M. Yu.; Bakhmutov, V. I.; Sivaev, I. B.; Teplitskaya, L. N.; Chizhevsky, I. T.; Pisareva, I. V.; Bregadze, V. I.; Epstein, L. M.; Shur, V. B. Chem.;Eur. J. 2001, 7, 3783. (19) Tikhonova, I. A.; Shubina, E. S.; Dolgushin, F. M.; Tugashov, K. I.; Teplitskaya, L. N.; Filin, A. M.; Sivaev, I. B.; Petrovskii, P. V.; Furin, G. G.; I.V.; Bregadze, V. I.; Epstein, L. M.; Shur, V. B. Izv. Akad. Nauk, Ser. Khim. 2003, 570 ( Russ. Chem. Bull., Int. Ed. Engl. 2003, 52, 594). (20) Tikhonova, I. A.; Dolgushin, F. M.; Tugashov, K. I.; Ellert, O. G.; Novotortsev, V. M.; Furin, G. G.; Antipin, M. Yu.; Shur, V. B. J. Organomet. Chem. 2004, 689, 82. (21) Haneline, M. R.; Gabbaı¨ , F. P. Angew. Chem., Int. Ed. 2004, 43, 5471. (22) Tikhonova, I. A.; Dolgushin, F. M.; Tugashov, K. I.; Petrovskii, P. V.; Antipin, M. Yu.; Shur, V. B. Izv. Akad. Nauk, Ser. Khim. 2004, 2754 (Russ. Chem. Bull., Int. Ed. Engl. 2004, 53, 2871). (23) Tikhonova, I. A.; Dolgushin, F. M.; Yakovenko, A. A.; Tugashov, K. I.; Petrovskii, P. V.; Furin, G. G.; Shur, V. B. Organometallics 2005, 24, 3395.

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Figure 2. ORTEP representation of the molecular structure of complex 5 with thermal ellipsoids drawn at the 50% probability level. The hydrogen atoms of the crown ether are omitted for clarity. Table 2. Selected Bond Lengths (A˚) and Angles (deg) in Complexes 5 and 6 5

6

Bond Lengths Hg(2)-O(2) Hg(2)-O(3) Hg(3)-O(1) Hg(1)-O(1W) Hg(2)-O(1W) Hg(3)-O(1W) O(1) 3 3 3 H(2W) O(1) 3 3 3 O(1W) O(1W)-H(2W) O(2A) 3 3 3 H(1W) O(2A) 3 3 3 O(1W)a O(1W)-H(1W)

2.830(2) 2.864(3) 3.142(3) 3.038(3) 2.05(8) 2.791(4) 0.75(6) 0.84(6)

3.186(4) 3.277(4) 2.816(2) 2.773(2) 3.123(2) 2.03(7) 2.752(4) 0.82(7) 2.09(7) 2.834(5) 0.76(7)

Bond Angles C(1)-Hg(1)-C(14) C(2)-Hg(2)-C(7) C(8)-Hg(3)-C(13) H(1W)-O(1W)-H(2W) O(1W)-H(2W) 3 3 3 O(1) O(1W)-H(1W) 3 3 3 O(2A)

176.27(13) 173.49(13) 175.94(13) 110(6) 173(4)

175.97(15) 174.60(14) 174.54(14) 101(6) 147(7) 165(8)

a Symmetry transformation -x þ 2, -y þ 1, -z þ 2 was used to generate equivalent atoms.

three Lewis acidic Hg sites of the adjacent anticrown, whereas one of the water protons forms a hydrogen bond with the oxygen atom of the crown ether, which is in agreement with the above-mentioned IR data. The Hg-O distances in this coordination fragment of 5 are 2.864(3), 3.142(3), and 3.038(3) A˚ (Table 2), and the hydrogen O(1) 3 3 3 H(2W) bond length is 2.05(8) A˚ (O(1) 3 3 3 O(1W) 2.791(4) A˚). An additional contribution in the formation of 5 is made by the interaction of one of the Hg centers of each anticrown unit with the nearest oxygen atom of [12]crown-4 (Hg(2)-O(2) 2.830(2) A˚). The complex of analogous composition, {[(o-C6F4Hg)3]2([18]crown-6)(H2O)2} (6), is formed in the interaction of 1

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Figure 3. ORTEP representation of the molecular structure of complex 6 with thermal ellipsoids drawn at the 50% probability level. The hydrogen atoms of the crown ether are omitted for clarity.

with an excess of aqueous [18]crown-6 in dry CH2Cl2 under Ar. The complex was isolated from the solution as colorless crystals in 79% yield. The IR spectrum of 6 is characterized by the presence of the broad ν(OH) bands at 3410-3419 and 3257-3263 cm-1. The room-temperature 199Hg NMR spectrum of 6 in THF ([6]0 = 8  10-2 mol 3 L-1) exhibits a downfield 199Hg shift of 6 ppm relative to that of neat 1. In the presence of a 40-fold excess of aqueous [18]crown-6, the value of this downfield shift is enhanced to 11 ppm. Figure 3 shows the structure of 6. Selected bond lengths and angles for 6 are listed in Table 2. The complex also has a double-decker sandwich structure wherein the crown ether and two water molecules are disposed between the mutually parallel planes of two anticrown units. As in 5, the molecules of H2O in 6 interact via the oxygen atom with three mercury centers of the neighboring mercuramacrocycle (Hg-O 2.816(2), 2.773(2), 3.123(2) A˚) and, in addition, form hydrogen bonds with the oxygen atoms of the crown ether. However, unlike in 5, both protons of every water molecule in 6 are involved in the formation of the H-bonds with the crown compound (O(1) 3 3 3 H(2W) 2.03(7) A˚, O(1) 3 3 3 O(1W) 2.752(4) A˚; O(2A) 3 3 3 H(1W) 2.09(7) A˚, O(2A) 3 3 3 O(1W) 2.834(5) A˚). The molecules of 1 in the complex also interact with the crown ether and are each coordinated by two of their Hg centers with two nearest oxygen atoms of the macrocyclic polyether (Hg-O 3.186(4) and 3.277(4) A˚). As a result, all six oxygen atoms of the [18]crown-6 ligand in complex 6 take part in the binding of the water and anticrown species. In the crystal, molecules of 5 and 6 form complex structures resulting mainly due to intermolecular aromatic stacking interactions between the C6F4 rings of the adjacent molecules of the adduct. The distances between the planes of these C6F4 rings in 5 and 6 range from 3.25 to 3.35 A˚, and the corresponding intermolecular C 3 3 3 C distances are in the range 3.24-3.53 A˚. The mutual orientation of the mercury macrocycles in sandwich complexes 4-6 corresponds to a staggered conformation, and the projections of their centroids onto the

Figure 4. ORTEP representation of the molecular structure of complex 7A with thermal ellipsoids drawn at the 50% probability level. The hydrogen atoms of the 1,3,5-trioxane molecule are omitted for clarity.

plane parallel to these cycles are shifted relative to each other by 5.16, 5.06, and 1.76 A˚, respectively. The reaction of a solution of 1 3 EtOH in dry diethyl ether with an excess (5:1) of 1,3,5-trioxane gives a colorless crystalline compound, which has been identified as a 1:1 trioxane complex, {[(o-C6F4Hg)3](CH2O)3} (7), on the basis of elemental analysis. The room-temperature 199Hg NMR spectrum of 7 in THF ([7]0 = 8  10-2 M) practically does not differ from that of free 1. In the presence of an excess of trioxane with respect to 7 (40:1), the 199Hg resonance is shifted downfield only by 2 ppm. Thus, complex 7, like 4, is virtually completely destroyed on dissolving in THF even when a large excess of the crown compound is present in the solution. An X-ray diffraction study of complex 7 revealed two independent molecules (7A and 7B) in its unit cell. The structure of one of these molecules (7A) is depicted in Figure 4. Like its 1,3,5-trithiane analogue 3,10 complex 7 also has a cage structure. Both 1 and the trioxane species in 7 behave as tridentate ligands and are bonded to one another in a face-on fashion. The Hg-O distances in 7A and 7B span

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Table 3. Selected Bond Lengths (A˚) and Angles (deg) in the Two Independent Molecules 7A and 7B 7A

7B

Bond Lengths Hg(1)-O(1) Hg(2)-O(2) Hg(3)-O(3)

2.830(6) 2.885(6) 2.849(6)

2.906(6) 2.821(6) 2.947(6)

Bond Angles C(1)-Hg(1)-C(14) C(2)-Hg(2)-C(7) C(8)-Hg(3)-C(13)

174.6(3) 174.5(3) 176.2(3)

175.4(3) 174.1(3) 175.2(3)

the range 2.821(6)-2.947(6) A˚ (av 2.87 A˚; Table 3). The trioxane molecule in the complex retains its chair conformation,24 and the geometry of the mercury anticrown does not change essentially as a result of the complexation. The plane formed by the oxygen atoms of the trioxane ligand in 7 is practically parallel to the mean plane of the central Hg3C6 cycle of 1 (the interplane angle in 7A and 7B is 0.4° and 2.0°, respectively). In the crystal, complex 7, like 3, forms centrosymmetric cofacial dimers due to shortened intermolecular Hg 3 3 3 Hg (3.770(1)-3.926(1) A˚) and Hg 3 3 3 C (3.359(8)-3.756(8) A˚) contacts between the neighboring molecules of 7. In each of the dimers, the mutually parallel planes of the central ninemembered rings of the mercury macrocycles are separated by 3.38 A˚ in 7A and by 3.34 A˚ in 7B, and the projections of the centroids of the Hg3C6 macrocyclic units onto the plane parallel to these units are shifted with respect to one another by 0.27 and 0.84 A˚ in 7A and 7B, respectively. A similar crystal packing was earlier observed for 1:1 adducts of 1 with nitrobenzene,9 n-butyronitrile,25 and acetone.26 The formation of 7 from 1 and trioxane like that of 3 from 1 and trithiane may be considered as a peculiar neutralization reaction of a cyclic multidentate Lewis acid with a cyclic multidentate Lewis base.

Conclusion Macrocycle 1 is able to bind anhydrous [12]crown-4 and 1,3,5-trioxane in dry diethyl ether with the formation of complexes 4 and 7, having double-decker sandwich and cage structures, respectively. In the case of 4, all four oxygen atoms of the crown compound but only two mercury centers of each anticrown species are involved in the complexation. In the case of 7, all three oxygen atoms of the crown compound and all three mercury sites of the anticrown take part in the bonding. The interaction of 1 with aqueous [12]crown-4 and [18]crown-6 in dry CH2Cl2 gives rise to sandwich complexes 5 and 6, containing two water and one crown ether molecules bonded to the mercury macrocycles. Remarkable structural features of these adducts are the η3coordination of the oxygen atom of the water species with the neighboring anticrown as well as the simultaneous participation of the water protons in the formation of the hydrogen bonds with the crown ether. The complex of analogous 2:1:2 composition, {[(o-C2B10H8Me2Hg)3]2(C6H6)(H2O)2} (8), (24) Busetti, V.; Del Pra, A.; Mammi, M. Acta Crystallogr., Sect. B 1969, 25, 1191. (25) Tikhonova, I. A.; Dolgushin, F. M.; Tugashov, K. I.; Furin, G. G.; Petrovskii, P. V.; Shur, V. B. Izv. Akad. Nauk, Ser. Khim. 2001, 1595. [ Russ. Chem. Bull., Int. Ed. Engl. 2001, 50, 1673]. (26) King, J. B.; Haneline, M. R.; Tsunoda, M.; Gabbaı¨ , F. P. J. Am. Chem. Soc. 2002, 124, 9350.

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and close structure has earlier been isolated by Hawthorne et al. from the interaction of o-carboranylmercury anticrown (o-C2B10H8Me2Hg)3 (9) with benzene and water in CH2Cl2.27 This sandwich complex, like 5 and 6, also contains the triply coordinated water ligands, each of which provides additionally both its protons for the formation of π-hydrogen bonds with benzene. However, unlike the crown ether species in 5 and 6, the benzene molecule in 8 does not interact with the Hg sites of the anticrown units. In the complex of 9 with acetone and water, {[(o-C2B10H8Me2Hg)3](Me2CO)3(H2O)} (10), the molecule of H2O is η3-coordinated with the Hg atoms of the macrocycle as well.27 The distances between the Hg centers and the oxygen atoms of the η3-coordinated water ligands in 8 and 10 (2.915(5) and 2.994(8) A˚) are comparable with the corresponding Hg-O separations for the η3-coordinated water molecules in 5 and 6 (2.773(2)-3.142(3) A˚: av 2.96 A˚). Similar values of the Hg-O distances for η3-coordinated neutral oxygenous Lewis bases are found in the structures of complexes of 1 with organic amides (2.777(4)-3.024(5) A˚),25,28,29 HMPA (2.824(4)-2.895(4) A˚),28 aldehydes and ketones (2.810(12)-3.056(14) A˚),23,26,30 ethyl acetate (2.848(5)-2.975(5) A˚),28 and DMSO (2.759(5)-3.120(5) A˚).28 The Hg-O bond lengths in complex 4 for the crown ether oxygen atoms coordinated to the Hg centers of 1 in an η2-type are 2.804(3) and 3.494(3) A˚ (Table 1). The first of these distances is close to those formed by the η2-coordinated THF molecules in the complex of THF with the mercury anticrown [o-C6H4HgOC(O)(CF2)3C(O)OHg]2 (2.85(4) A˚),31 whereas the other above-mentioned Hg-O distance is much longer. Complexes 4-7 contain also the crown ether oxygen atoms, which are η1-coordinated to the Hg sites of 1 with Hg-O separations of 3.083(3) A˚ in 4, 2.830(2) A˚ in 5, 3.186(4) and 3.277(4) A˚ in 6, and 2.830(6)-2.947(6) A˚ in 7. These distances are essentially longer than the Hg-O distances formed by the η1-coordinated THF molecules in the THF complex of the o-carboranylmercury anticrown (oC2B10H10Hg)4 (2.65(2) A˚).32 The Hg-O bond lengths for the η1-coordinated acetone,30 ethyl acetate,28 and DMSO28 in their 3:1 complexes with 1 are equal to 3.088(8), 2.881(6), and 2.819(5)/2.991(6) A˚, respectively. In the THF complexes of 1, {[(o-C6F4Hg)3](THF)n} (where n= 1 - 4), the Hg-O distances range from 3.029(11) to 3.621(9) A˚ (av 3.24 A˚) for the η1-coordinated THF and from 2.853(3) to 3.430(7) A˚ (av 3.14 A˚) for the η3-coordinated THF.14 The η4-coordinated molecules of diethylformamide in its 2:1 adduct with the dicationic mercury anticrown {[o-C6Me4HgO(H)Hg]2}2þ form the Hg-O bond distances ranging from 2.83(1) to 2.96(1) A˚ (av 2.91 A˚),33 which is comparable with the Hg-O separations observed for the η3-coordinated N,N-dimethylacetamide (2.777(4)-2.988(4) A˚; av 2.86 A˚)25 and DMF (2.799(5)-3.024(5) A˚; av 2.87 A˚)28,29 species in their 2:1 adducts with 1. (27) Lee, H.; Knobler, C. B.; Hawthorne, M. F. Angew. Chem., Int. Ed. 2001, 40, 3058. (28) Tikhonova, I. A.; Dolgushin, F. M.; Tugashov, K. I.; Petrovskii, P. V.; Furin, G. G.; Shur, V. B. J. Organomet. Chem. 2002, 654, 123. (29) Baldamus, J.; Deacon, G. B.; Hey-Hawkins, E.; Junk, P. C.; Martin, C. Aust. J. Chem. 2002, 55, 195. (30) King, J. B.; Tsunoda, M.; Gabbaı¨ , F. P. Organometallics 2002, 21, 4201. (31) Wuest, J. D.; Zacharie, B. J. Am. Chem. Soc. 1987, 109, 4714. (32) Yang, X.; Johnson, S. E.; Khan, S. I.; Hawthorne, M. F. Angew. Chem., Int. Ed. Engl. 1992, 31, 893. (33) Vaugeois, J.; Simard, M.; Wuest, J. D. Organometallics 1998, 17, 1215.

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Table 4. Crystal Data, Data Collection, and Structure Refinement Parameters for 4-7 4

5

formula C44H16F24Hg6O4 C44H20F24Hg6O6 molecular wt 2268.11 2304.14 cryst size (mm) 0.20  0.06  0.03 0.42  0.14  0.10 cryst syst monoclinic triclinic P1 space group P21/n a (A˚) 11.4171(6) 10.8129(3) b (A˚) 14.1322(7) 10.8204(3) c (A˚) 14.3817(7) 12.4980(5) R (deg) 113.8890(10) β (deg) 96.1120(10) 104.5110(10) γ (deg) 103.5090(10) 2307.3(2) 1198.02(7) V (A˚3) Z 2 1 -3 3.265 3.194 Dcalcd (g 3 cm ) -1 20.031 19.294 linear absorption (μ) (cm ) 0.033/0.150 0.129/0.391 Tmin/Tmax 60 64 2θmax (deg) 6701 (0.0515) 8311 (0.0378) no. of unique reflns (Rint) no. of obsd reflns (I > 2σ(I)) 5820 7454 no. of params 352 369 0.0248 0.0204 R1 (on F for obsd reflns)a 0.0524 0.0447 wR2 (on F2 for all reflns)b GOOF 1.023 1.028 P P P a b 2 2 2 P 2 2 1/2 R1 = ||Fo| - |Fc||/ |Fo|. wR2 = { [w(Fo - Fc ) ]/ [w(Fo ) ]} .

Experimental Section The starting macrocycle 1 and its ethanol adduct 1 3 EtOH were prepared according to the published procedures.16a,14 Anhydrous [18]crown-6 was obtained from commercial, aqueous [18]crown-6 (Reanal; 98%) by recrystallization from dry acetonitrile with subsequent decomposition of the resulting acetonitrile adduct under vacuum at 50 °C for 8-9 h.34 Commercial [12]crown-4 (Fluka; 99%) and 1,3,5-trioxane (Fluka; 99%) were used without additional purification. Solvents were purified by conventional methods and freshly distilled prior to use over calcium hydride (CH3CN), P2O5 (CH2Cl2), sodium (n-hexane) or from sodium/benzophenone (ether) under Ar. The 199 Hg NMR spectra were recorded on a Bruker Av-600 instrument using a 0.2 M solution of Ph2Hg in pyridine (δ=-791.1 ppm35) as an external standard. The IR spectra of complexes were recorded as Nujol mulls on a Nicolet Magna-IR 750 Series II Fourier spectrometer. Synthesis of {[(o-C6F4Hg)3]2([12]crown-4)} (4). To a solution of anhydrous [12]crown-4 (0.08 mL, 0.5 mmol) in diethyl ether (2 mL) was added in an Ar atmosphere a solution of 1 3 C2H5OH (0.1090 g, 0.1 mmol) in a mixture of ether (2 mL) and ethanol (0.05 mL). After 20-30 min, colorless crystals of complex 4 began to precipitate. After 1 h, the reaction mixture was slowly concentrated for 3-4 h to 1 mL and was allowed to stand for 3 days under Ar at 22 °C. Then, the resulting crystals were separated by decanting of the mother liquor under Ar, washed with ether (1 mL) and n-hexane (3  1 mL), and dried at 22 °C in vacuo for 3 h. Yield of 4: 0.0435 g (38%). Anal. Calcd for C44H16F24O4Hg6: C, 23.30; H, 0.71; F, 20.10. Found: C, 23.49; H, 0.66; F, 20.29. Synthesis of {[(o-C6F4Hg)3]2([12]crown-4)(H2O)2} (5). To a solution of 1 (0.1047 g, 0.1 mmol) in dry CH2Cl2 (14 mL) was added aqueous [12]crown-4 (0.08 mL) under Ar. After 2 h, the reaction solution was slowly concentrated for 26 h to 1 mL, and the precipitated colorless crystals of complex 5 were filtered under Ar, washed with CH2Cl2 (2  0.5 mL) and n-hexane (3  1 mL), and dried at 22 °C in vacuo for 3 h. Yield of 5: 0.0796 g (34) Gokel, G. W.; Cram, D. J.; Liotta, C. L.; Harris, H. P.; Cook, F. L. J. Org. Chem. 1974, 39, 2445. (35) Grishin, Yu. K.; Strelenko, Yu. A.; Margulis, L. A.; Ustynyuk, Yu. A.; Golovchenko, L. S.; Peregudov, A. S.; Kravtsov, D. N. Dokl. Akad. Nauk SSSR 1979, 249, 892.

6

7

C48H28F24Hg6O8 2392.24 0.30  0.28  0.16 triclinic P1 11.6411(7) 11.7927(7) 11.8557(7) 112.960(1) 98.081(1) 109.041(1) 1347.88(14) 1 3.238 17.158 0.079/0.170 64 9338 (0.0370) 8194 388 0.0235 0.0497 1.007

C21H6F12Hg3O3 1136.03 0.14  0.10  0.03 triclinic P1 10.6447(5) 10.6655(5) 20.8733(9) 82.389(1) 76.329(1) 89.550(1) 2281.67(18) 4 3.307 20.259 0.158/0.582 60 13 278 (0.0678) 9411 703 0.0385 0.0748 0.0964

(69%). Anal. Calcd for C44H20F24O6Hg6: C, 22.94; H, 0.87; F, 19.79. Found: C, 23.47; H, 1.03; F, 19.90. IR (νOH, cm-1): 3632, 3363 (br), 3234 (br). In the other experiment, to a solution of 1 (0.1049 g, 0.1 mmol) in dry CH2Cl2 (14 mL) was added on air anhydrous [12]crown-4 (0.08 mL, 0.5 mmol). After 2 h, the slightly turbid solution was filtered off and the filtrate was slowly evaporated for 9 h to 2 mL. The resulting colorless crystals of complex 5 were separated, washed with CH2Cl2 (0.5 mL) and n-hexane (3  1 mL), and dried at 22 °C in vacuo for 4 h. Yield of 5: 0.0786 g (68%). Anal. Calcd for C44H20F24O6Hg6: C, 22.94; H, 0.87; F, 19.79. Found: C, 23.19; H, 0.98; F, 19.96. IR (νOH, cm-1): 3632, 3365 (br), 3234 (br). Synthesis of {[(o-C6F4Hg)3]2([18]crown-6)(H2O)2} (6). To a solution of 1 (0.1045 g, 0.1 mmol) in dry CH2Cl2 (15 mL) was added aqueous [18]crown-6 (0.1227 g) under Ar. In ca. 1 min, the reaction solution became turbid and a fine crystalline precipitate of complex 6 began to form. After 4 h, the resulting 6 was filtered under Ar, washed with CH2Cl2 (3  1 mL), and dried in vacuo for 3 h. Yield of 6: 0.0603 g (50%). Anal. Calcd for C48H28F24O8Hg6: C, 24.10; H, 1.18. Found: C, 24.53; H, 1.13. IR (νOH, cm-1): 3413 (br), 3259 (br). A slow concentration of the filtrate for 29 h to 1 mL gave an additional amount of the crystalline complex 6, which was filtered off in an Ar atmosphere, washed with CH2Cl2 (0.5 mL) and n-hexane (3  1 mL), and dried at 22 °C in vacuo for 4 h. Yield of 6: 0.0347 g (29%). Anal. Calcd for C48H28F24O8Hg6: C, 24.10; H, 1.18. Found: C, 23.86; H, 1.52. IR (νOH, cm-1): 3414 (br), 3263 (br). The overall yield of 6 is 79%. Synthesis of {[(o-C6F4Hg)3](CH2O)3} (7). To a solution of 1 3 EtOH (0.1095 g, 0.1 mmol) in ether (3 mL) was added at room temperature a solution of 1,3,5-trioxane (0.0457 g, 0.5 mmol) in ether (2 mL). Immediately, the reaction solution became turbid and after 10 min a colorless crystalline precipitate began to form. The next day, the reaction mixture was allowed to slowly evaporate to 2 mL at 22 °C, and the resulting colorless crystals of complex 7 were filtered off, washed with ether (4  0.5 mL), and dried at 22 °C in vacuo for 2 h. Yield of 7: 0.0609 g (58%). Anal. Calcd for C21H6F12O3Hg3: C, 22.20; H, 0.53; F, 20.07. Found: C, 22.66; H, 0.51; F, 19.98. X-ray Diffraction Study. Single-crystal X-ray diffraction experiments were carried out with a Bruker SMART APEX II diffractometer (graphite-monochromated Mo KR radiation,

Article λ = 0.71073 A˚, ω-scan technique, T = 100 K). The APEX II software36 was used for collecting frames of data, indexing reflections, determination of lattice constants, integration of intensities of reflections, scaling, and absorption correction, and SHELXTL37 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 the anisotropic thermal parameters for all non-hydrogen atoms. The hydrogen atoms of the water molecules in structures 5 and 6 were located in difference Fourier synthesis and refined isotropically. The hydrogen atoms of the crown ethers in 4-7 were (36) APEX II software package; Bruker AXS Inc.: Madison, WI, 2005. (37) SHELXTL v. 5.10, Structure Determination Software Suite; Bruker AXS Inc.: Madison, WI, 1998.

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placed geometrically and included in the structure factor calculations in the riding motion approximation. The main experimental and crystallographic parameters for 4-7 are presented in Table 4.

Acknowledgment. This work was supported by the Russian Foundation for Basic Research (project code 08-03-00332) and the Russian Science Support Foundation (K.I.T.). Supporting Information Available: Tables of crystal data and structure refinement, atomic coordinates, bond lengths and angles, anisotropic displacement parameters, and hydrogen coordinates for 4-7. This material is available free of charge via the Internet at http://pubs.acs.org.