Transition-Metal(II)–Crown-Ether–Polyiodides - Crystal Growth

ARTICLE pubs.acs.org/crystal

Transition-Metal(II) Crown-Ether Polyiodides Christoph Fiolka, Ingo Pantenburg, and Gerd Meyer* Department f€ur Chemie, Anorganische Festk€orper- und Koordinationschemie, Universit€at zu K€oln, Greinstrasse 6, D-50939 K€oln, Germany ABSTRACT: The crown-ethers 12-crown-4 (12c4) and benzo-12-crown-4 (b12c4) encapsulate divalent manganese, iron, cobalt, and nickel cations building large sandwichtype dications with square-antiprismatic coordination polyhedra; benzo-15-crown-5 (b15c5) forms in-cavity complexes with six-plus-one coordinate Mn(II) and Co(II). The anions are a variety of polyiodides, I3 , I5 , I7 , I122 , I162 , and I184 . The crystal structures of 12 new compounds have been determined, 8 of which contain 12-crown-4: [Mn(12c4)2](I3)2(12c4) (1) and [Co(12c4)2](I3)2(12c4) (2) are isotypic (monoclinic, C2/c, No. 15) and contain isolated triiodide anions. Isotypic [Mn(12c4)2](I5)2 (3) and [Ni(12c4)2](I5)2 (4) (monoclinic, Cm, No. 8) feature V/L-shaped I5 anions which are connected to zigzag chains. The hexadecaiodides, built of nonaiodide and heptaiodide subunits, in the isotypic compounds [Mn(12c4)2](I16) (5), [Fe(12c4)2](I16) (6), [Co(12c4)2](I16) (7) (orthorhombic, Pna21, No. 33) exhibit a new structural motif for I162 anions. The elusive octadecaiodide I184 in [Co(12c4)2]2(I18) (8) (monoclinic, C2/c, No. 15) consists of a linear pentaiodide to which iodine and triiodide are attached. Analogous reactions with benzo-12-crown4 yielded the pentaiodides [Mn(b12c4)2](I5)2 (9) and [Co(b12c4)2](I5)2 (10). 9 features a trans-pentaiodide chain to which an additional pentaiodide is connected; it also contains an isolated pentaiodide anion. The crystal structure of 10 contains isolated V/Lshaped pentaiodide anions exclusively. The anionic parts in [Co(b15c5)2(MeCN)(H2O)](I7)2 (11) (monoclinic, Cc, No. 9) and [Mn(b15c5)2(H2O)2](I12) (12) (monoclinic, P21/c, No. 14) are determined by polymeric pyramidal heptaiodides in 11 and by a two-dimensional network of dodecaiodide anions with twisted sawhorse geometry in 12.

’ INTRODUCTION Shortly after the element iodine was discovered two centuries ago, polyiodides were first observed. The first crystal structure determination had to wait until 1935, for (NH4)I3.1 Meanwhile, the structural chemistry of polyiodides has developed considerably, and hundreds of structures have been determined.2,3 Many of these polyiodides have been discovered by fortunate coincidence when the syntheses of other compounds were designed. These are mostly triiodides; [Cs(b18c6)2](I3) and [Cs2(b18c6)3](I3)2 are recent examples with sandwich and tripledecker cations.4 Polyiodides may be constructed (formally and literally) by adding iodine, I2, to iodide, I . A number of series with different charges in accord with the general formula I2m+nn (with m and n integers larger than zero, n = 1, 4)3 have been shown to exist. As much as crystal growth is often straightforward and a large area may be covered in a reasonable time, the design of specific polyiodide anions or anionic networks is difficult to achieve. Only very slowly patterns emerge. To date there is no definitive prescription of how a desired polyiodide anion and/or a special anionic architecture could be constructed. Larger cations, however, seem to have a templating effect, attested for example by the largest polyiodide anion known, I293 , with three large ferrocenium cations.5 Crown ethers with encapsulated (metal) cations offer a wide range of shape and charge around which polyiodide anions of different sizes and geometries as well as charges can be arranged. [Lu(H2O)3(db18c6)(Thf)6]4(I3)2(I5)6(I8)(I12) is an especially prolific example when the giant cations and the four r 2011 American Chemical Society

different polyiodide anions forming a three-dimensional network are regarded.6 In a more general approach, we have investigated the influence of different cations (H3O+, H5O2+, mono-, di-, and trivalent metal cations), encapsulated in crown-ethers of different sizes, on the formation of polyiodide networks. Apart from the choice of crown-ethers and cations and the concentrations of iodine and iodide, the solvents also play an important role. The present picture is also dictated by the solubility product as single crystals are needed for structure determination, which is the only reliable method to determine the composition of the salt that crystallizes from a specific solution. As part of a broad study, we here report on a number of new metal(II) crown-ether polyiodides with the general formulas [M(crown)2]2+([I2m+1] )2 (m = 1, 2, 3) and [M(crown)2]2+[I2m+2]2 (m = 5, 7, 8) with M = Fe, Mn, Co, Ni employing relatively small crown-ethers, 12crown-4 (12c4), benzo-12-crown-4 (b12c4), and benzo-15crown-5 (b15c5).

’ EXPERIMENTAL SECTION Syntheses. Generally, the polyiodide salts [M(crown)2]2+([I2m+1] )2

(m = 1, 2, 3) and [M(crown)2]2+[I2m+2]2 (m = 5, 7, 8) were synthesized by dissolving metal diiodide, MI2 (M = Mn, Fe, Co, Ni), Received: September 13, 2011 Revised: October 2, 2011 Published: October 04, 2011 5159

dx.doi.org/10.1021/cg201198t | Cryst. Growth Des. 2011, 11, 5159–5165

Crystal Growth & Design

ARTICLE

Table 1. Experimental Parameters for the Synthesis of Polyiodides compound [Mn(12c4)2](I3)2(12c4) (1)

starting materials MnI2(H2O)4, 12c4, I2 (1:2:2, 0.1 mmol)

solventa MeCN

elemental analysisb C 21.43; H 3.60 C 22.49; H 3.85

[Co(12c4)2](I3)2(12c4) (2)

CoI2, 12c4, I2 (1:2:2, 0.1 mmol)

[Mn(12c4)2](I5)2 (3)

MnI2(H2O)4, 12c4, I2 (1:2:4, 0.1 mmol)

MeCN Thf

[Ni(12c4)2](I5)2 (4)

NiI2, 12c4, I2 (1:2:4, 0.1 mmol)

Thf

[Mn(12c4)2](I16) (5)

MnI2(H2O)4, 12c4, I2 (1:2:7, 0.1 mmol)

Dcm, EtOH

[Fe(12c4)2](I16) (6)

FeI2, 12c4, I2 (1:2:7, 0.1 mmol)

Dcm, EtOH

[Co(12c4)2](I16) (7) [Co(12c4)2]2(I18) (8)

CoI2, 12c4, I2 (1:2:7, 0.1 mmol) CoI2, 12c4, I2 (1:1:4, 0.1 mmol)

Dcm, EtOH MeCN

C 12.37; H 2.08 C 12.86; H 3.92

[Mn(b12c4)2](I5)2 (9)

MnI2(H2O)4, 12c4, I2 (1:2:4, 0.1 mmol)

Dcm, EtOH

C 16.26; H 1,82 C 15.10; H 2.12

[Co(b12c4)2](I5)2 (10)

CoI2, 12c4, I2 (1:1:1, 0.1 mmol)

MeCN

[Co(b15c5)2(MeCN)(H2O)](I7)2 (11)

CoI2, 12c4, I2 (1:1:6, 0.1 mmol)

MeCN

[Mn(b15c5)2(H2O)2](I12) (12)

MnI2(H2O)4, 12c4, I2 (1:2:5, 0.1 mmol)

MeCN, H2O

C 15.64; H 2.06 C 15.91; H 1.97

a

MeCN: acetonitrile; Thf: tetrahydrofuran; Dcm: dichlormethane; EtOH: ethanol. b First line: calculated from formula; second line: measured. No data: only single crystals were available. The sample of 8 had apparently some MeCN, that of 9 some water absorbed. the respective crown-ether and iodine in different proportions in 40 mL of a solvent or solvent mixture (acetonitrile, ethanol, tetrahydrofuran, dichloromethane, water were the ones used in this work), eventually by heating to moderate temperatures, filtrating, and letting the solution stand in a beaker covered with perforated Parafilm until crystallization occurs. Table 1 gives details. The crystals have brown to black color, depending upon the cation to iodine ratio; very iodine rich polyiodides even have a metallic luster. Crystal Structure Determinations. Single crystals suitable for X-ray diffraction were selected under a microscope and sealed in thinwalled glass capillaries. These were mounted on Stoe Image Plate diffractometers (IPDS-I or -II; Stoe & Cie., Darmstadt, Germany), and complete intensity data sets were collected. The data were corrected for Lorentz and polarization effects. A numerical absorption correction based on crystal-shape optimization was applied for all data. The programs used were Stoe’s X-Area as well as SHELXS-97 and SHELXL-97 for structure solution and refinement.7 The last cycles of refinement included atomic positions and anisotropic thermal parameters for all atoms. The crystal structures of 5, 6, and 11 were refined as inversion twins with a BASF (batch scale factor) of 0.25(7) 5, 0.27(5) 6, and 0.23(7) 11. In the case of 11 the corresponding centro-symmetric space group C2/c generates poor crystallographic data and disorder; therefore, space group Cc was chosen for 11. The absolute structure parameter of 7 is 0.06(9). The crystal structure of the isotypic compounds [M(12c4)2](I5)2 with M = Mn (3) and Ni (4) shows disorder of the polyether in the centrosymmetric space group C2/m. Space groups Cm and C2 were checked and disorder could be resolved in Cm. Crystallographic data and structure solution and refinement details are summarized in Table 2 and have been deposited in more detail with the Cambridge Crystallographic Data Centre as supplementary publications Nos. CCDC-840446 to 840457 (see Table 2). Copies of the data can be obtained, free of charge, on application to CHGC, 12 Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336033 or e-mail: [email protected]).

’ RESULTS AND DISCUSSION Twelve new salts with divalent transition-metal cations (M = Mn, Fe, Co, Ni) included in an oxygen-atom coordination sphere

of crown-ether ligands (12c4, b12c4, b15c5; in two cases water and acetonitrile, respectively, are also coordinating) with polyiodide anions have been obtained from solution; see Table 1 for details. The polyiodide anions belong to two series, [I2m+1] (with m = 1, 2, 3) and [I2m+2]2 (with m = 5, 7, 8). Although the equilibria in solution are not known and the solubility products of the precipitated salts are also unknown, a general trend can be seen: with a metal to crown-ether ratio of generally 1:2, the amount of iodine added correlates with the number of iodine atoms in the polyiodide network of the respective salt. For example, with a molar ratio of metal/crown-ether/iodine of 1:2:2 six iodine atoms (two triiodide anions) form the anionic part of the structure, and the other ratios are 1:2:4 (pentaiodide), 1:2:5 (dodecaiodide), ... 1:2:7 (hexadecaiodide). There are, however, exceptions: [Co(12c4)2]I18 (8) was obtained applying a 1:1:4 ratio. In the following, we discuss the cations first which are always isolated from each other, then the anionic polyiodide part of the structure, followed by a view on the packing of cations and anions. Metal(II) Crown-Ether Cations. The 12-crown-4 ligand has a cavity of about 130 150 pm in diameter.8 This cavity is apparently too small for the divalent cations of manganese, iron, cobalt, and nickel. Thus, they prefer sandwich-type arrangements in the cations [M(12c4)2]2+. These divalent cations have highspin ionic radii of about 90 pm for coordination number 8 (based on the ionic radius of O2 of 140 pm).9 This amounts to an expected M2+ O2 distance of 210 pm. As Table 3 shows, the real distances are considerably larger, with rather small distance ranges. For example, for [Co(12c4)2](I3)2(12c4) (2), M2+ O2 distances range from 224.0(3) to 229.4(3) pm, with an average of 227.0 pm. The coordination polyhedron of all of the cations [M(12c4)2]2+ (1 8) and [M(b12c4)2]2+ (9, 10) may be described as a square antiprism (see Figures 1 and 2) with torsion angles almost perfectly at 45° for a square antiprism; see Table 3. The benzo groups in the [M(b12c4)2]2+ cations are in an anti conformation. The cations in [Co(b15c5)2(MeCN)(H2O)](I7)2 (11) and [Mn(b15c5)2(H2O)2](I12) (12) consist of in-cavity metal(II) benzo-15-crown-5 complexes. (The occupancy of the manganese 5160

dx.doi.org/10.1021/cg201198t |Cryst. Growth Des. 2011, 11, 5159–5165

Crystal Growth & Design

ARTICLE

Table 2. Crystal Data and Refinement Paramaters for Transition-Metal Crown-Ether Polyiodides complex

1

2

3

4

5

6 C16H32O8I16Fe

empirical formula

C24H48O12I6Mn

C24H48O12I6Co

C16H32O8I10Mn

C16H32O8I10Ni

C16H32O8I16Mn

fw

1344.96

1348.95

1676.36

1680.13

2437.76

2438.67

temperature (K)

293(2)

293(2)

293(2)

293(2)

170(2)

100(2)

crystal system

monoclinic

monoclinic

monoclinic

monoclinic

orthorhombic

orthorhombic

space group

C2/c (No. 15)

C2/c (No. 15)

Cm (No. 8)

Cm (No. 8)

Pna21 (No. 33)

Pna21 (No. 33)

a (pm)

1673.2(4)

1678.4(2)

2153.8(3)

2153.8(5)

2362.9(2)

2359.8(1)

b (pm)

1539.5(2)

1545.7(1)

854.0(1)

855.5(1)

1199.6(1)

1188.7(1)

c (pm) α (deg)

1625.9(2)

1619.8(2)

1098.9(2)

1101.2(2)

1704.8(1)

1700.0(1)

β (deg)

109.47(1)

109.47(1)

109.06(7)

109.17(2)

volume (106 pm3)

3948.5(11)

3961.9(7)

1910.4(4)

1916.3(7)

4832.1(5)

4768.7(4)

Z

4

4

2

2

4

4 3.397

γ (deg)

Fcalcd (Mg/m3)

2.263

2.262

2.914

2,912

3.351

μ (mm 1)

5.075

5.158

8.457

8.593

10.527

10.706

R1 [I > 2.0σ(I)]a wR2 (all data)a

0.0437 0.0887

0.0316 0.0873

0.0559 0.1630

0.0382 0.0869

0.0445 0.1335

0.0439 0.0690

CCDC No.

840449

840450

840451

840452

840453

840454

7

8

9

11

12

complex empirical formula

C16H32O8I16Co

C32H64O16I18Co2

C24H32O8I10Mn

C24H32O8I10Co

C30H45O11NI14Co

C28H44O12I12Mn

fw

2441.75

3106.89

1772.44

1776.43

2431.20

2150.37

temperature (K)

170(2)

170(2)

170(2)

170(2)

170(2)

293(2)

crystal system

orthorhombic

monoclinic

triclinic

monoclinic

monoclinic

monoclinic

space group a (pm)

Pna21 (No. 33) 2371.5(2)

C2/c (No. 15) 4179.6(4)

P1 (No. 2) 1249.7(2)

P21/c (No. 14) 1464.2(1)

Cc (No. 9) 1731.3(2)

P21/c (No. 14) 1267.6(2)

b (pm)

1193.9(1)

853.3(1)

1544.4(2)

1607.0(1)

1765.6(2)

2390.0(3)

c (pm)

1701.5(1)

2258.6(3)

2190.3(2)

2284.4(2)

1917.2(2)

872.2(1)

128.84(1)

97,32(1)

90.87(1)

α (deg)

88.39(1)

β (deg)

118.82(1)

80.73(1)

γ (deg)

82.97(1)

volume (106 pm3)

4817.5(6)

7057.5(13)

4140.5(9)

4187.1(5)

5812.8(10)

2641.9(6)

Z Fcalcd (Mg/m3)

4 3.367

4 2.924

4 2.843

4 2.818

4 2.778

2 2.703

μ (mm 1)

10.641

8.393

7.813

7.821

7.775

7.307

R1 [I > 2.0σ(I)]a

0.0467

0.0308

0.0398

0.0426

0.0674

0.0471

wR2 (all data)a

0.1219

0.0813

0.0893

0.1136

0.1803

0.1272

CCDC No.

840455

840456

840457

840446

840447

840448

Fc2)2]/Σ[w(Fo2)2]]1/2, R1 = Σ Fo|

site in 12 is 0.5.) In the case of 11, one acetonitrile and one water molecule are attached such that the coordination polyhedron may be described as a pentagonal bipyramid, Figure 2. The water molecule is η2-coordinated by hydrogen bonding to a second benzo-15-crown-5 molecule with d(OH2 Ocrown) = 279.4 and 287.1 pm, respectively. The coordination polyhedron in 12 is, again, a pentagonal bipyramid with two apical water molecules; see Figure 2. Polyiodide Anions. In the 12 crystal structures which have been determined during the present exploratory study, there are five polyiodide anions belonging to the series [I2m+1] (with m = 1, 2, 3, i.e., (I3) , (I5) , and (I7) ) and [I2m+2]2 (with m = 5, 7, i.e., (I12)2 , (I16)2 ) that have been observed. The anion (I18)4 as observed in [Co(12c4)2]2(I18) (8) is a special case. The structures of these—and for polyiodide anions in general—are

|Fc /Σ|Fo|. )

Definitions: wR2 = [Σ[w(Fo2

)

a

10

usually unpredictable because of a multitude of effects which influence their composition, charge, and conformation. To these effects belong (the unknown) equilibria in solution, packing/ matric effects due to size and charge of the cations, and the optimization of electrostatic interactions. Despite the large sandwich cation [M(12c4)]2+ (M = Mn, Co), the triiodide anions (I3) in 1 and 2, [M(12c4)2](I3)2(12c4), are slightly asymmetric with distances of 286.8(1) and 293.8(1) pm in 1 and 287.7(1) and 296.8(1) pm in 2 and with I I I angles of 176.2(1)° and 176.4(1)°, respectively. The crystal structure consists of layers of cations and uncoordinated crown-ether between which the triiodide anions are situated; see Figure 3. Pentaiodide ions, (I5) , occur in the crystal structures of [M(12c4)2](I5)2, M = Mn (3), Ni (4), as well as in [M(b12c4)2](I5)2, M = Mn (9), Co (10). The pentaiodide ions in 3 and 4 5161

dx.doi.org/10.1021/cg201198t |Cryst. Growth Des. 2011, 11, 5159–5165

Crystal Growth & Design

ARTICLE

Table 3. Metal(II)-Ion Oxygen Distances in the Cations [M(12c4)2]2+, [M(b12c4)2]2+, and [M(b15c5)]2+ as well as Angles u Determining the Deviation of the Coordination Polyhedron from a Cube compound

d(M2+ O2 )/pm; /pm

j/°

[Mn(12c4)2](I3)2(12c4) (1)

229.6(5) 234.4(9); 232.2

45.0(8)

[Co(12c4)2](I3)2(12c4) (2) [Mn(12c4)2](I5)2 (3)

224.0(3) 229.4(3); 227.0 226.2(11) 236.0(10); 230.9

45.0(1) 45.0(1)

[Ni(12c4)2](I5)2 (4)

224.4(11) 229.8(9); 227.2

45.0(3)

[Mn(12c4)2](I16) (5)

228.7(12) 236.8(11); 230.8

45.0(1)

[Fe(12c4)2](I16) (6)

224.6(11) 232.4(12); 228.6

45.0(2)

[Co(12c4)2](I16) (7)

221.7(14) 232.2(16); 227.1

45.0(2)

[Co(12c4)2]2(I18) (8)

225.1(3) 229.6(3); 226.9

45.0(3)

[Mn(b12c4)2](I5)2 (9)

225.0(8) 239.0(8); 230.7

45.1(4)

[Co(b12c4)2](I5)2 (10) [Co(b15c5)2(MeCN)(H2O)](I7)2 (11)

216.6(6) 233.4(6); 225.1 217.6(16) 225.2(15); 221.4

45.4(1)

[Mn(b15c5)2(H2O)2](I12) (12)

217.5(7) 229.8(6); 224.3

Figure 1. The sandwich-type cations [M(12c4)2]2+ and [M(b12c4)2]2+ in the crystal structures of 1 8 (top) and of 9 and 10 (bottom), respectively.

Figure 2. The cations [Co(b15c5)(MeCN)(H2O)(b15c5)]2+ (left) and [Mn(b15c5)(H2O)2]2+ (right) in the crystal structures of [Co(b15c5)2(MeCN)(H 2 O)](I 7 )2 (11) and [Mn(b15c5)2 (H 2 O)2 ](I 12 ) (12), respectively.

Figure 3. Projection of the crystal structure of [M(12c4)2](I3)2(12c4), M = Mn (1), Co (2) onto (010).

show a rather usual L-type structure, consisting of an asymmetric (I3) with an I2 molecule attached; these (I5) anions are further connected to double zigzag chains (Figure 4). The pentaiodide ions in [Mn(b12c4)2](I5)2 (9) are partly also connected to cischains with an additional pentaiodide attached at 362 pm. There are also isolated L-shaped (I5) in the structure of 9 with the shortest I I contact to the chains of 386 pm. It is surprising that

[Co(b12c4)2](I5)2 (10) is not isotypic and has all L-shaped (I5) isolated in a sense that the shortest I I contacts between them are 382 pm. These distances are considered indicative for only weak bonding interactions; twice the van der Waals radius of iodine would be roughly 400 pm.10 The heptaiodide anion, (I7) , in the crystal structure of [Co(b15c5)2(MeCN)(H2O)](I7)2 (11) has a rather common 5162

dx.doi.org/10.1021/cg201198t |Cryst. Growth Des. 2011, 11, 5159–5165

Crystal Growth & Design geometry, consisting of a central iodide ion to which three iodine molecules are attached (see Figure 5), with distances of I I I of 301.5(1), 321.8(1), 329.6(1) and 273.2(1), 276.4(1), 284.9(1) pm, respectively, in a pyramidal conformation. The central I is 317.8 pm above a plane through the three outer iodine atoms. The (I 7) ions are attached to each other forming a double chain and further to a three-dimensional network with I I contacts around 355 pm. This rather dense network leaves cavities for the [Co(b15c5)2(MeCN)(H2O)]2+ cations (Figure 5).

Figure 4. L-shaped pentaiodide ions, (I5) and their arrangement in the crystal structures of [M(12c4)2](I5)2, M = Mn (3), and Ni (4). (top), as well as in [M(b12c4)2](I5)2, M = Mn (9), bottom left, and M = Co (10), bottom right.

ARTICLE

The centrosymmetric dodecaiodide (I12)2 in the crystal structure of [Mn(b15c5)2(H2O)2](I12) (12) shows a rather characteristic twisted sawhorse conformation; see the Newman projection in Figure 6. In (I12)2 , a central iodine molecule is attached to two pentaiodide anions. These consist of an asymmetric triiodide anion with distances of 299.6(1) and 284.4(1) pm and with the I I I angle of 178.2(1)° to which an iodine molecule is attached at a distance of 344.4(1) pm. The terminal iodine atoms of the (I12)2 ions approach four such ions at a distance of 350.5(3) pm resulting in a two-dimensional network of I26-membered rings. Each ring accommodates two [Mn(b15c5)2(H2O)2]2+ cations. The hexadecaiodide ion in the crystal structures of [M(12c4)2](I16), M = Mn (5), Fe (6), Co (7), consists of pyramidal nonaiodide and pyramidal heptaiodide subunits. In (I9) , an apical iodide ion is pyramidally coordinated by four iodine molecules, with the I I distances ranging from 326.2(1) to 336.4(1) pm in 5, 324.8(1) to 333.8(1) pm in 6, and 327.0(2) to 332.8(2) pm in 7. This nonaiodide subunit in the structures of 5 7 is special, and the (I16)2 anions built therefrom differ from previously observed (I16)2 anions,11 13 which are either built from (I5) or (I7) anions and I2 molecules. The (I7) subunit in the present (I16)2

Figure 5. The heptaiodide ions, (I7) , in the crystal structure of [Co(b15c5)2(MeCN)(H2O)](I7)2 (11), top, and the three-dimensional polyiodide network with the cations in channels. 5163

dx.doi.org/10.1021/cg201198t |Cryst. Growth Des. 2011, 11, 5159–5165

Crystal Growth & Design

ARTICLE

Figure 6. Newman projection of the centrosymmetric dodecaiodide in [Mn(b15c5)2(H2O)2](I12) (12) and the two-dimensional polyiodide network with the cations in channels down [001].

Figure 7. Left: Two hexadecaiodide anions (I16)2 encapsulating a [M(12c4)2]2+ cation in the crystal structure of [M(12c4)2](I16), M = Mn (5), Fe (6), Co (7); right: the three-dimensional polyiodide network.

consists of an asymmetric triiodide with distances of 281.1(2) and 307.4(2) pm in 5, 282.1(1) to 306.4(1) pm in 6, and 280.7(2) to 308.4(2) pm in 7, to which two iodine molecules are attached at 323.8(1) and 334.5(1) pm in 5, 3.238(1) and 3.345(1) pm in 6, and 3.236(2) and 336.0(2) pm in 7. The triiodide subunit in (I7) is linked to one terminal iodine atom of (I9) , at distances of 360.4(2) pm in 5, 356.9(1) pm in 6, and 361.7(2) pm in 7, resulting finally in (I16)2 anions. Two of these ions almost encapsulate one [M(12c4)2]2+ cation and are linked by a multitude of van der Waals interactions to a three-dimensional network as shown in Figure 7. The anionic part of the crystal structure of the salt [Co(12c4)2](I9), or better [Co(12c4)2]2(I18) (8), consists of a central planar nonaiodide, (I9) , to which four triiodide ions are attached at distances of 324.0(4) and 347.8(4) pm, respectively. An “isolated” nonaiodide anion of this planar structure has not been observed so far, and one would expect tetrahedral geometry, but see the pyramidal configuration in (I9) as incorporated in (I16)2 , Figure 7. However, we have recently observed the poly interhalide

Figure 8. One [(I9)(I3)2/1(I3)2/2]4 = (I18)4 chain (left) in the crystal structure of [Co(12c4)2]2(I18) (8) and the arrangement of these chains leaving channels for the cations (right). 5164

dx.doi.org/10.1021/cg201198t |Cryst. Growth Des. 2011, 11, 5159–5165

Crystal Growth & Design [Cl(I2)4] which has such a planar structure with Cl I distances of 300 303 pm.14 Four almost symmetric (I3) anions are attached to (I9) in [Co(12c4)2]2(I18) at distances of 339.9(5) pm and angles of 94.65(2)°. This unit, [(I9)(I3)4] = [I21] is connected via two (I3) to a chain, [(I9)(I3)2/1(I3)2/2]4 = (I18)4 ; see Figure 8. The chains are stacked in the [010] direction on top of each other and arranged in a way that channels form that accommodate the [Co(12c4)2]2+ cations (Figure 8). The only other known (I18)4 is described as built of two octaiodide ions interlinked by an iodine molecule.15

ARTICLE

(13) Morse, D. B.; Rauchfuss, T. B.; Wilson, S. R. J. Am. Chem. Soc. 1990, 635, 112. (14) Walbaum, C. Dissertation, Universit€at zu K€oln, 2009. (15) Bigoli, F.; Deplano, P.; Devillanova, F. A.; Lippolis, V.; Mercuri, M. L.; Pellinghelli, M. A.; Trogu, E. T. Inorg. Chim. Acta 1998, 267, 115.

’ CONCLUSIONS In a rather broad exploratory study, we have observed salts of two series, [M(crown)2]2+([I2m+1] )2 (m = 1, 2, 3) and [M(crown)2]2+[I2m+2]2 (m = 5, 7), M = Mn, Fe, Co, Ni, as well as [Co(12c4)2]2(I18). The cations M2+ are encapsulated mostly in sandwich type structures with 12-crown-4 and benzo12-crown-4, [M(12c4)2]2+ and [M(b12c4)2]2+, with coordination numbers of 8. In only two cases, [Co(b15c5)2(MeCN)(H2O)](I7)2 and [Mn(b15c5)2(H2O)2](I12), solvent molecules are included in the cationic structures. These large cations seem to have a templating effect on the anionic polyiodide structure. Iodine-poor salts, with (I3) ions, form layered structures, and iodine richer salts form channels to accommodate the cations, or both layers and channels. Out of these, although not always unambiguously, anions of the compositions [I2m+1] (m = 1, 2, 3, 4, i.e., (I3) , (I5) , (I7) , (I9) ) and [I2m+2]2 (m = 5, 7, i.e., (I12)2 , (I16)2 ) may be cut out, following the usual rules. ’ AUTHOR INFORMATION Corresponding Author

*E-mail: [email protected].

’ DEDICATION Dedicated to the memory of Professor Kurt Dehnicke, Marburg, Germany. ’ REFERENCES (1) Mooney, R. C. L. Z. Kristallogr. 1935, 90, 143. (2) Tebbe, K.-F. In Homopolyatomic Rings, Chains, Macromolecules of Main-Group Elements; Rheingold, A. L., Ed.; Elsevier: Amsterdam, 1977; p 551. (3) Svensson, H.; Kloo, L. Chem. Rev. 2003, 103, 1649–1684. (4) Herzmann, N.; Pantenburg, I.; M€uller, I.; Tyrra, W.; Meyer, G. Z. Anorg. Allg. Chem. 2006, 632, 2209–2216. (5) Tebbe, K.-F.; Buchem, R. Angew. Chem., Int. Ed. Engl. 1997, 36, 1345–1346. (6) Walbaum, C.; Pantenburg, I.; Junk, P; Deacon, G. B.; Meyer, G. Z. Anorg. Allg. Chem. 2010, 636, 1444–1446. (7) X-Shape 1.06, Crystal Optimisation for Numerical Absorption Correction (C); Stoe & Cie GmbH: Darmstadt, 1999; X-Area 1.16; Stoe & Cie GmbH: Darmstadt, 2003; X-RED 1.22, Stoe Data Reduction Program (C); Stoe & Cie GmbH: Darmstadt, 2001; X-STEP32, Revision 1.06f; STOE & Cie GmbH: Darmstadt, 2000; Sheldrick, G. M SHELXL-97, Programs for Crystal Structure Analysis; Universit€at G€ottingen: G€ottingen, Germany, 1997. (8) Constable, E. C. Coordination Chemistry of Macrocyclic Compounds; Oxford University Press: New York, 1999; p 21. (9) Shannon, R. D. Acta Crystallogr. 1976, A32, 751–767. (10) Bondi, A. J. Phys. Chem. 1964, 68, 441–451. (11) Tebbe, K.-F.; Gilles, T. Z. Anorg. Allg. Chem. 1996, 622, 138. (12) Tebbe, K.-F.; Loukili, R. Z. Anorg. Allg. Chem. 1998, 624, 1175. 5165

dx.doi.org/10.1021/cg201198t |Cryst. Growth Des. 2011, 11, 5159–5165